1
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Lopez-Astacio H, Vargas-Perez BL, Del Valle-Perez A, Pollock CJ, Cunci L. Open-source electrochemical cell for in situ X-ray absorption spectroscopy in transmission and fluorescence modes. J Synchrotron Radiat 2024; 31:322-327. [PMID: 38306299 PMCID: PMC10914171 DOI: 10.1107/s1600577524000122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 01/04/2024] [Indexed: 02/04/2024]
Abstract
X-ray spectroscopy is a valuable technique for the study of many materials systems. Characterizing reactions in situ and operando can reveal complex reaction kinetics, which is crucial to understanding active site composition and reaction mechanisms. In this project, the design, fabrication and testing of an open-source and easy-to-fabricate electrochemical cell for in situ electrochemistry compatible with X-ray absorption spectroscopy in both transmission and fluorescence modes are accomplished via windows with large opening angles on both the upstream and downstream sides of the cell. Using a hobbyist computer numerical control machine and free 3D CAD software, anyone can make a reliable electrochemical cell using this design. Onion-like carbon nanoparticles, with a 1:3 iron-to-cobalt ratio, were drop-coated onto carbon paper for testing in situ X-ray absorption spectroscopy. Cyclic voltammetry of the carbon paper showed the expected behavior, with no increased ohmic drop, even in sandwiched cells. Chronoamperometry was used to apply 0.4 V versus reversible hydrogen electrode, with and without 15 min of oxygen purging to ensure that the electrochemical cell does not provide any artefacts due to gas purging. The XANES and EXAFS spectra showed no differences with and without oxygen, as expected at 0.4 V, without any artefacts due to gas purging. The development of this open-source electrochemical cell design allows for improved collection of in situ X-ray absorption spectroscopy data and enables researchers to perform both transmission and fluorescence simultaneously. It additionally addresses key practical considerations including gas purging, reduced ionic resistance and leak prevention.
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Affiliation(s)
- Hiram Lopez-Astacio
- Department of Chemistry and Physics, Universidad Ana G. Mendez at Gurabo, Gurabo, Puerto Rico, USA
| | - Brenda Lee Vargas-Perez
- Department of Chemistry, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico, USA
| | - Angelica Del Valle-Perez
- Department of Chemistry and Physics, Universidad Ana G. Mendez at Gurabo, Gurabo, Puerto Rico, USA
- Department of Chemistry, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico, USA
| | - Christopher J. Pollock
- Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, NY 14853, USA
| | - Lisandro Cunci
- Department of Chemistry, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico, USA
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2
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Xu W, Zeng R, Rebarchik M, Posada-Borbón A, Li H, Pollock CJ, Mavrikakis M, Abruña HD. Atomically Dispersed Zn/Co-N-C as ORR Electrocatalysts for Alkaline Fuel Cells. J Am Chem Soc 2024; 146:2593-2603. [PMID: 38235653 DOI: 10.1021/jacs.3c11355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Hydrogen fuel cells have drawn increasing attention as one of the most promising next-generation power sources for future automotive transportation. Developing efficient, durable, and low-cost electrocatalysts, to accelerate the sluggish oxygen reduction reaction (ORR) kinetics, is urgently needed to advance fuel cell technologies. Herein, we report on metal-organic frameworks-derived nonprecious dual metal single-atom catalysts (SACs) (Zn/Co-N-C), consisting of Co-N4 and Zn-N4 local structures. These catalysts exhibited superior ORR activity with a half-wave potential (E1/2) of 0.938 V versus RHE (reversible hydrogen electrode) and robust stability (ΔE1/2 = -8.5 mV) after 50k electrochemical cycles. Moreover, this remarkable performance was validated under realistic fuel cell working conditions, achieving a record-high peak power density of ∼1 W cm-2 among the reported SACs for alkaline fuel cells. Operando X-ray absorption spectroscopy was conducted to identify the active sites and reveal catalytic mechanistic insights. The results indicated that the Co atom in the Co-N4 structure was the main catalytically active center, where one axial oxygenated species binds to form an Oads-Co-N4 moiety during the ORR. In addition, theoretical studies, based on a potential-dependent microkinetic model and core-level shift calculations, showed good agreement with the experimental results and provided insights into the bonding of oxygen species on Co-N4 centers during the ORR. This work provides a comprehensive mechanistic understanding of the active sites in the Zn/Co-N-C catalysts and will pave the way for the future design and advancement of high-performance single-site electrocatalysts for fuel cells and other energy applications.
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Affiliation(s)
- Weixuan Xu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Rui Zeng
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Michael Rebarchik
- Department of Chemical & Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Alvaro Posada-Borbón
- Department of Chemical & Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Huiqi Li
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Christopher J Pollock
- Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Manos Mavrikakis
- Department of Chemical & Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Héctor D Abruña
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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3
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Dong Y, Yuan Z, Huang S, Xue Z, Yu X, Pollock CJ, Torbert RB, Burch JL. Observational evidence of accelerating electron holes and their effects on passing ions. Nat Commun 2023; 14:7276. [PMID: 37949855 PMCID: PMC10638271 DOI: 10.1038/s41467-023-43033-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 10/27/2023] [Indexed: 11/12/2023] Open
Abstract
As a universal structure in space plasma, electron holes represent an obvious signature of nonlinear process. Although the theory has a 60-year history, whether electron hole can finally accelerate ambient electrons (or ions) is quite controversial. Previous theory for one-dimensional holes predicts that net velocity change of passing electrons (or ions) occurs only if the holes have non-zero acceleration. However, the prediction has not yet been demonstrated in observations. Here, we report four electron holes whose acceleration/deceleration is obtained by fitting the spatial separations and detection time delays between different Magnetospheric Multiscale spacecraft. We find that electron hole acceleration/deceleration is related to the ion velocity distribution gradient at the hole's velocity. We observe net velocity changes of ions passing through the accelerating/decelerating holes, in accordance with theoretical predictions. Therefore, we show that electron holes with non-zero acceleration can cause the velocity of passing ions to increase in the acceleration direction.
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Affiliation(s)
- Yue Dong
- School of Electronic Information, Wuhan University, Wuhan, China
| | - Zhigang Yuan
- School of Electronic Information, Wuhan University, Wuhan, China.
| | - Shiyong Huang
- School of Electronic Information, Wuhan University, Wuhan, China
| | - Zuxiang Xue
- School of Electronic Information, Wuhan University, Wuhan, China
| | - Xiongdong Yu
- School of Electronic Information, Wuhan University, Wuhan, China
| | | | - R B Torbert
- Physics Department, University of New Hampshire, Durham, NH, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, TX, USA
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4
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Feijóo J, Yang Y, Fonseca Guzman MV, Vargas A, Chen C, Pollock CJ, Yang P. Operando High-Energy-Resolution X-ray Spectroscopy of Evolving Cu Nanoparticle Electrocatalysts for CO 2 Reduction. J Am Chem Soc 2023; 145:20208-20213. [PMID: 37677089 DOI: 10.1021/jacs.3c08182] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
Advances in electrocatalysis research rely heavily on building a thorough mechanistic understanding of catalyst active sites under realistic operating conditions. Only recently have techniques emerged that enable sensitive spectroscopic data collection to distinguish catalytically relevant surface sites from the underlying bulk material under applied potential in the presence of an electrolyte layer. Here, we demonstrate that operando high-energy-resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) is a powerful spectroscopic method which offers critical surface chemistry insights in CO2 electroreduction with sub-electronvolt energy resolution using hard X-rays. Combined with the high surface area-to-volume ratio of 5 nm copper nanoparticles, operando HERFD-XAS allows us to observe with clear evidence the breaking of chemical bonds between the ligands and the Cu surface as part of the ligand desorption process occurring under electrochemical potentials relevant for the CO2 reduction reaction (CO2RR). In addition, the dynamic evolution of oxidation state and coordination number throughout the operation of the nanocatalyst was continuously tracked. With these results in hand, undercoordinated metallic copper nanograins are proposed to be the real active sites in the CO2RR. This work emphasizes the importance of HERFD-XAS compared to routine XAS in catalyst characterization and mechanism exploration, especially in the complicated electrochemical CO2RR.
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Affiliation(s)
- Julian Feijóo
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Yao Yang
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Miller Institute for Basic Research in Science, University of California, Berkeley, California 94720, United States
| | - Maria V Fonseca Guzman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Alfred Vargas
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
| | - Chubai Chen
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Christopher J Pollock
- Cornell High Energy Synchrotron Source, Cornell University, Ithaca, New York 14853, United States
| | - Peidong Yang
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
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5
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Pollock CJ, Debefve LM. Resonant Excitation Unlocks Chemical Selectivity of Platinum Lβ Valence-to-Core X-ray Emission Spectra. Inorg Chem 2023; 62:13681-13691. [PMID: 37578150 PMCID: PMC10467576 DOI: 10.1021/acs.inorgchem.3c01930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Indexed: 08/15/2023]
Abstract
Valence-to-core X-ray emission spectroscopy (VtC XES) is an emerging technique that uses hard X-rays to probe the valence electronic structure of an absorbing atom. Despite finding varied applications for light elements and first row transition metals, little work has been done on heavier elements such as second and third row transition metals. This lack of application is at least partially due to the relatively low resolution of the data at the high energies required to measure these elements, which obscures the useful chemical information that can be extracted from the lower energy, higher resolution spectra of lighter elements. Herein, we collect data on a set of platinum-containing compounds and demonstrate that the VtC XES resolution can be dramatically enhanced by exciting the platinum atom in resonance with its L3-edge white line absorption. Whereas spectra excited using standard nonresonant absorption well above the Pt L3-edge display broad, unfeatured VtC regions, resonant XES (RXES) spectra have more than twofold improved resolution and are revealed to be rich in chemical information with the ability to distinguish between even closely related species. We further demonstrate that these RXES spectra may be used to selectively probe individual components of a mixture of Pt-containing compounds, establishing this technique as a viable probe for chemically complex samples. Lastly, it is shown that the spectra are interpretable using a molecular orbital framework and may be calculated using density functional theory, thus suggesting resonant excitation as a general strategy for extracting chemically useful information from heavy element VtC spectra.
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Affiliation(s)
- Christopher J. Pollock
- Cornell High Energy Synchrotron Source,
Wilson Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Louise M. Debefve
- Cornell High Energy Synchrotron Source,
Wilson Laboratory, Cornell University, Ithaca, New York 14853, United States
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6
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Xu W, Lang S, Wang K, Zeng R, Li H, Feng X, Krumov MR, Bak SM, Pollock CJ, Yeo J, Du Y, Abruña HD. Fundamental mechanistic insights into the catalytic reactions of Li─S redox by Co single-atom electrocatalysts via operando methods. Sci Adv 2023; 9:eadi5108. [PMID: 37585528 PMCID: PMC10431713 DOI: 10.1126/sciadv.adi5108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 07/14/2023] [Indexed: 08/18/2023]
Abstract
Lithium-sulfur batteries represent an attractive option for energy storage applications. A deeper understanding of the multistep lithium-sulfur reactions and the electrocatalytic mechanisms are required to develop advanced, high-performance batteries. We have systematically investigated the lithium-sulfur redox processes catalyzed by a cobalt single-atom electrocatalyst (Co-SAs/NC) via operando confocal Raman microscopy and x-ray absorption spectroscopy (XAS). The real-time observations, based on potentiostatic measurements, indicate that Co-SAs/NC efficiently accelerates the lithium-sulfur reduction/oxidation reactions, which display zero-order kinetics. Under galvanostatic discharge conditions, the typical stepwise mechanism of long-chain and intermediate-chain polysulfides is transformed to a concurrent pathway under electrocatalysis. In addition, operando cobalt K-edge XAS studies elucidate the potential-dependent evolution of cobalt's oxidation state and the formation of cobalt-sulfur bonds. Our work provides fundamental insights into the mechanisms of catalyzed lithium-sulfur reactions via operando methods, enabling a deeper understanding of electrocatalysis and interfacial dynamics in electrical energy storage systems.
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Affiliation(s)
- Weixuan Xu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Shuangyan Lang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Kaiyang Wang
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Rui Zeng
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Huiqi Li
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Xinran Feng
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Mihail R. Krumov
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Seong-Min Bak
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Christopher J. Pollock
- Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, NY, 14853, USA
| | - Jingjie Yeo
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Yonghua Du
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Héctor D. Abruña
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
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7
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Liu ZY, Zong QG, Rankin R, Zhang H, Hao YX, He JS, Fu SY, Wu HH, Yue C, Pollock CJ, Le G. Particle-sounding of the spatial structure of kinetic Alfvén waves. Nat Commun 2023; 14:2088. [PMID: 37045846 PMCID: PMC10097679 DOI: 10.1038/s41467-023-37881-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 03/30/2023] [Indexed: 04/14/2023] Open
Abstract
Kinetic Alfvén waves (KAWs) are ubiquitous throughout the plasma universe. Although they are broadly believed to provide a potential approach for energy exchange between electromagnetic fields and plasma particles, neither the detail nor the efficiency of the interactions has been well-determined yet. The primary difficulty has been the paucity of knowledge of KAWs' spatial structure in observation. Here, we apply a particle-sounding technique to Magnetospheric Multiscale mission data to quantitatively determine the perpendicular wavelength of KAWs from ion gyrophase-distribution observations. Our results show that KAWs' perpendicular wavelength is statistically 2.4[Formula: see text] times proton thermal gyro-radius. This observation yields an upper bound of the energy the majority proton population can reach in coherent interactions with KAWs, that is, roughly 5.76 times proton perpendicular thermal energy. Therefore, the method and results shown here provide a basis for unraveling the effects of KAWs in dissipating energy and accelerating particles in a number of astrophysical systems, e.g., planetary magnetosphere, astrophysical shocks, stellar corona and wind, and the interstellar medium.
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Affiliation(s)
- Z-Y Liu
- Institute of Space Physics and Applied Technology, Peking University, Beijing, China
| | - Q-G Zong
- Institute of Space Physics and Applied Technology, Peking University, Beijing, China.
- Key laboratory of solar activity and space weather, National Space Science Center, Chinese Academy of Sciences, Beijing, China.
- Polar Research Institute of China, Shanghai, China.
| | - R Rankin
- Department of Physics, University of Alberta, Edmonton, AB, Canada
| | - H Zhang
- Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Y-X Hao
- Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany
| | - J-S He
- Institute of Space Physics and Applied Technology, Peking University, Beijing, China
| | - S-Y Fu
- Institute of Space Physics and Applied Technology, Peking University, Beijing, China
| | - H-H Wu
- School of Electronic Information, Wuhan University, Wuhan, China
| | - C Yue
- Institute of Space Physics and Applied Technology, Peking University, Beijing, China
| | | | - G Le
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
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8
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Yang Y, Louisia S, Yu S, Jin J, Roh I, Chen C, Fonseca Guzman MV, Feijóo J, Chen PC, Wang H, Pollock CJ, Huang X, Shao YT, Wang C, Muller DA, Abruña HD, Yang P. Operando studies reveal active Cu nanograins for CO 2 electroreduction. Nature 2023; 614:262-269. [PMID: 36755171 DOI: 10.1038/s41586-022-05540-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 70.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 11/08/2022] [Indexed: 02/10/2023]
Abstract
Carbon dioxide electroreduction facilitates the sustainable synthesis of fuels and chemicals1. Although Cu enables CO2-to-multicarbon product (C2+) conversion, the nature of the active sites under operating conditions remains elusive2. Importantly, identifying active sites of high-performance Cu nanocatalysts necessitates nanoscale, time-resolved operando techniques3-5. Here, we present a comprehensive investigation of the structural dynamics during the life cycle of Cu nanocatalysts. A 7 nm Cu nanoparticle ensemble evolves into metallic Cu nanograins during electrolysis before complete oxidation to single-crystal Cu2O nanocubes following post-electrolysis air exposure. Operando analytical and four-dimensional electrochemical liquid-cell scanning transmission electron microscopy shows the presence of metallic Cu nanograins under CO2 reduction conditions. Correlated high-energy-resolution time-resolved X-ray spectroscopy suggests that metallic Cu, rich in nanograin boundaries, supports undercoordinated active sites for C-C coupling. Quantitative structure-activity correlation shows that a higher fraction of metallic Cu nanograins leads to higher C2+ selectivity. A 7 nm Cu nanoparticle ensemble, with a unity fraction of active Cu nanograins, exhibits sixfold higher C2+ selectivity than the 18 nm counterpart with one-third of active Cu nanograins. The correlation of multimodal operando techniques serves as a powerful platform to advance our fundamental understanding of the complex structural evolution of nanocatalysts under electrochemical conditions.
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Affiliation(s)
- Yao Yang
- Department of Chemistry, University of California, Berkeley, CA, USA.,Miller Institute for Basic Research in Science, University of California, Berkeley, CA, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Sheena Louisia
- Department of Chemistry, University of California, Berkeley, CA, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Sunmoon Yu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.,Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Jianbo Jin
- Department of Chemistry, University of California, Berkeley, CA, USA
| | - Inwhan Roh
- Department of Chemistry, University of California, Berkeley, CA, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Chubai Chen
- Department of Chemistry, University of California, Berkeley, CA, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Maria V Fonseca Guzman
- Department of Chemistry, University of California, Berkeley, CA, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Julian Feijóo
- Department of Chemistry, University of California, Berkeley, CA, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Peng-Cheng Chen
- Department of Chemistry, University of California, Berkeley, CA, USA.,Kavli Energy NanoScience Institute, Berkeley, CA, USA
| | - Hongsen Wang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | | | - Xin Huang
- Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, USA
| | - Yu-Tsun Shao
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Cheng Wang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Héctor D Abruña
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Peidong Yang
- Department of Chemistry, University of California, Berkeley, CA, USA. .,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. .,Department of Materials Science and Engineering, University of California, Berkeley, CA, USA. .,Kavli Energy NanoScience Institute, Berkeley, CA, USA.
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9
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Kitamura N, Amano T, Omura Y, Boardsen SA, Gershman DJ, Miyoshi Y, Kitahara M, Katoh Y, Kojima H, Nakamura S, Shoji M, Saito Y, Yokota S, Giles BL, Paterson WR, Pollock CJ, Barrie AC, Skeberdis DG, Kreisler S, Le Contel O, Russell CT, Strangeway RJ, Lindqvist PA, Ergun RE, Torbert RB, Burch JL. Direct observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth. Nat Commun 2022; 13:6259. [PMID: 36307443 PMCID: PMC9616889 DOI: 10.1038/s41467-022-33604-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 09/22/2022] [Indexed: 11/30/2022] Open
Abstract
Electromagnetic whistler-mode waves in space plasmas play critical roles in collisionless energy transfer between the electrons and the electromagnetic field. Although resonant interactions have been considered as the likely generation process of the waves, observational identification has been extremely difficult due to the short time scale of resonant electron dynamics. Here we show strong nongyrotropy, which rotate with the wave, of cyclotron resonant electrons as direct evidence for the locally ongoing secular energy transfer from the resonant electrons to the whistler-mode waves using ultra-high temporal resolution data obtained by NASA’s Magnetospheric Multiscale (MMS) mission in the magnetosheath. The nongyrotropic electrons carry a resonant current, which is the energy source of the wave as predicted by the nonlinear wave growth theory. This result proves the nonlinear wave growth theory, and furthermore demonstrates that the degree of nongyrotropy, which cannot be predicted even by that nonlinear theory, can be studied by observations. Excitation of whistler-mode waves by cyclotron instability is considered as the likely generation process of the waves. Here, the authors show direct observational evidence for locally ongoing secular energy transfer from the resonant electrons to the whistler-mode waves in Earth’s magnetosheath.
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Affiliation(s)
- N Kitamura
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan. .,Department of Earth and Planetary Science, Graduate School of Science, the University of Tokyo, Tokyo, Japan.
| | - T Amano
- Department of Earth and Planetary Science, Graduate School of Science, the University of Tokyo, Tokyo, Japan
| | - Y Omura
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan
| | - S A Boardsen
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,Goddard Planetary Heliophysics Institute, University of Maryland, Baltimore County, MD, USA
| | - D J Gershman
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Y Miyoshi
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - M Kitahara
- Department of Geophysics, Graduate school of Science, Tohoku University, Sendai, Japan
| | - Y Katoh
- Department of Geophysics, Graduate school of Science, Tohoku University, Sendai, Japan
| | - H Kojima
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan
| | - S Nakamura
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - M Shoji
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - Y Saito
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - S Yokota
- Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - B L Giles
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - W R Paterson
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | | | - A C Barrie
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,Aurora Engineering, Potomac, MD, USA
| | - D G Skeberdis
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,a.i. solutions Inc, Lanham, MD, USA
| | - S Kreisler
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,Aurora Engineering, Potomac, MD, USA
| | - O Le Contel
- Laboratoire de Physique des Plasmas, CNRS/Sorbonne Université/Université Paris-Saclay/Observatoire de Paris/Ecole Polytechnique Institut Polytechnique de Paris, Paris, France
| | - C T Russell
- Department of Earth, Planetary, and Space Science, University of California, Los Angeles, CA, USA
| | - R J Strangeway
- Department of Earth, Planetary, and Space Science, University of California, Los Angeles, CA, USA
| | | | - R E Ergun
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - R B Torbert
- Department of Physics, University of New Hampshire, Durham, NH, USA.,Southwest Research Institute, San Antonio, TX, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, TX, USA
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10
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Frontini F, Lebert BW, Cho KK, Song MS, Cho BK, Pollock CJ, Kim YJ. Intermediate valence state in YbB 4revealed by resonant x-ray emission spectroscopy. J Phys Condens Matter 2022; 34:345601. [PMID: 35667370 DOI: 10.1088/1361-648x/ac7629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
We report the temperature dependence of the Yb valence in the geometrically frustrated compoundYbB4from 12 to 300 K using resonant x-ray emission spectroscopy at the YbLα1transition. We find that the Yb valence,v, is hybridized between thev = 2 andv = 3 valence states, increasing fromv=2.61±0.01at 12 K tov=2.67±0.01at 300 K, confirming thatYbB4is a Kondo system in the intermediate valence regime. This result indicates that the Kondo interaction inYbB4is substantial, and is likely to be the reason whyYbB4does not order magnetically at low temperature, rather than this being an effect of geometric frustration. Furthermore, the zero-point valence of the system is extracted from our data and compared with other Kondo lattice systems. The zero-point valence seems to be weakly dependent on the Kondo temperature scale, but not on the valence change temperature scaleTv.
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Affiliation(s)
- Felix Frontini
- Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7, Canada
| | - Blair W Lebert
- Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7, Canada
| | - K K Cho
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 61005 Gwangju, Republic of Korea
| | - M S Song
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 61005 Gwangju, Republic of Korea
| | - B K Cho
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 61005 Gwangju, Republic of Korea
| | - Christopher J Pollock
- Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853, United States of America
| | - Young-June Kim
- Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7, Canada
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11
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Debefve LM, Pollock CJ. Systematic assessment of DFT methods for geometry optimization of mononuclear platinum-containing complexes. Phys Chem Chem Phys 2021; 23:24780-24788. [PMID: 34714314 DOI: 10.1039/d1cp01851e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Platinum is used extensively as a catalyst for a wide variety of chemical reactions, though its scarcity and price present limitations to expansions of its use. To understand the origin of platinum's versatility-with the goals of both improving the efficiency of existing catalysts and mimicking its reactivity with more abundant metals-the mechanisms of platinum-catalyzed chemical reactions must be understood via structural and spectroscopic characterization of these catalysts under operando conditions. Such data, typically consisting of complex mixtures of species, often prove challenging to interpret, inviting the aid of chemical theory. DFT calculations in particular have proven successful at predicting structural and spectroscopic parameters of transition metal species, though a thorough investigation of how these methods perform for platinum-based complexes has yet to be undertaken. Herein, we evaluated the performance of geometry optimization for five commonly used functionals (BP86, PBE, B3LYP, PBE0, and TPSSh) in combination with various ligand basis sets, relativistic approximations, and solvation and dispersion models. We applied these DFT methods to a training set of 14 platinum-containing complexes with varying sizes, oxidation states, and number and type of ligands and determined that the best-performing method was the PBE0 functional together with the def2-TZVP basis set for the ligand atoms, the ZORA relativistic approximation, and solvation and dispersion corrections. The ability of this DFT methodology to accurately predict metrical parameters was confirmed using two case studies, most notably by comparing the DFT optimized geometry of a previously uncharacterized complex to newly collected EXAFS data, which showed excellent agreement.
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Affiliation(s)
- Louise M Debefve
- Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, New York 14853, USA.
| | - Christopher J Pollock
- Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, New York 14853, USA.
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12
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Branston CJ, Capilla-Lasheras P, Pollock CJ, Griffiths K, White S, Dominoni DM. Urbanisation weakens selection on the timing of breeding and clutch size in blue tits but not in great tits. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03096-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Abstract
Urbanisation is a globally occurring phenomenon and is predicted to continue increasing rapidly. Urban ecosystems present novel environments and challenges which species must acclimate or adapt to. These novel challenges alter existing or create new selection pressures on behaviours which provide an opportunity to investigate eco-evolutionary responses to contemporary environmental change. We used 7 years of breeding data from urban and forest populations of blue and great tits to understand whether selection for timing of breeding or clutch size differed between the two habitats and species. We found that urban great tits laid eggs earlier than their forest counterparts, but there was no evidence of a difference in selection for earlier breeding. Blue tits, however, did not differ in timing of egg laying between the two habitats, but selection for earlier laying was weaker in the urban environment. Both species laid smaller clutches in the urban site and had positive selection for larger clutch sizes which did not differ in strength for the great tits but did for blue tits, with weaker selection in the urban population. Our results suggest that food availability for nestlings may be constraining urban birds, and that the temporal cues females use to time breeding correctly, such as tree budburst and food availability, may be absent or reduced in urban areas due to lower caterpillar availability. These results have implications for our understanding of the adaptation of wild animals to city life.
Significance statement
Urbanisation is expanding rapidly and changing the environment many species live in. A key challenge is to understand how species adapt to the urban environment, why some species can adapt, why others cannot and what we can do to ensure that cities are ecologically sustainable and biodiversity rich. Here we show that the strength of natural selection for early breeding and larger clutch size is weaker in urban than non-urban blue tits, likely due to reduced and irregular availability of natural insect food in urban areas. This effect was not found in great tits. Thus, urbanisation can alter the selection pressures wild animals are exposed to, but this effect may differ between species, even when closely related. This has implications for our understanding of how species adapt to urban life.
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13
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Pollock CJ, Lane JV, Buckingham L, Garthe S, Jeavons R, Furness RW, Hamer KC. Risks to different populations and age classes of gannets from impacts of offshore wind farms in the southern North Sea. Mar Environ Res 2021; 171:105457. [PMID: 34482114 DOI: 10.1016/j.marenvres.2021.105457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/17/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
The southern North Sea holds the world's highest concentration of offshore wind farms (OWFs). Northern gannets (Morus bassanus), a species considered at high risk from OWF impacts, show a strong seasonal peak there in November, but it is unclear which populations and age classes are most at risk of collision with wind turbines. We tagged adult and juvenile gannets at the world's largest colony (Bass Rock) and reviewed two sources of survey data for different age classes to study their movements through southern North Sea waters. Tracked birds showed peak numbers in the southern North Sea in mid-October, with much smaller numbers there during November. Adults were distributed throughout the area, including waters close to OWFs, whereas juveniles were confined to the coast. Survey data indicated high proportions of immature gannets in southern North Sea waters, suggesting higher collision risk than for adults. Gannets present in November may be predominantly from colonies further north than Bass Rock.
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Affiliation(s)
| | - Jude V Lane
- School of Biology, University of Leeds, Leeds, UK
| | - Lila Buckingham
- UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, UK
| | - Stefan Garthe
- Research and Technology Centre (FTZ), University of Kiel, Büsum, Germany
| | - Ruth Jeavons
- School of Biology, University of Leeds, Leeds, UK
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14
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Soto-Pérez J, Betancourt LE, Trinidad P, Larios E, Rojas-Pérez A, Quintana G, Sasaki K, Pollock CJ, Debefve LM, Cabrera CR. In Situ X-ray Absorption Spectroscopy of PtNi-Nanowire/Vulcan XC-72R under Oxygen Reduction Reaction in Alkaline Media. ACS Omega 2021; 6:17203-17216. [PMID: 34278107 PMCID: PMC8280705 DOI: 10.1021/acsomega.1c00792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 06/15/2021] [Indexed: 06/13/2023]
Abstract
Studying the oxygen reduction reaction (ORR) in the alkaline electrolyte has proven to promote better catalytic responses and accessibility to commercialization. Ni-nanowires (NWs) were synthesized via the solvothermal method and modified with Pt using the spontaneous galvanic displacement method to obtain PtNi-NWs. Carbon Vulcan XC-72R (V) was used as the catalyst support, and they were doped with NH3 to obtain PtNi-NWs/V and PtNi-NWs/V-NH3. Their electrocatalytic response for the ORR was tested and PtNi-NWs/V provided the highest specific activity with logarithmic values of 0.707 and 1.01 (mA/cm2 Pt) at 0.90 and 0.85 V versus reversible hydrogen electrode (RHE), respectively. PtNi-NWs showed the highest half-wave potential (E 1/2 = 0.89 V) at 1600 rpm and 12 μgPt/cm2 in 0.1 M KOH at 25.00 ± 0.01 °C. Additionally, the catalysts followed a four-electron pathway according to the Koutecký-Levich analysis. Moreover, durability experiments demonstrated that the PtNi-NW/V performance loss was like that of commercial Pt/V along 10,000 cycles. Electrochemical ORR in situ X-ray absorption spectroscopy results showed that the Pt L3 edge white line in the PtNi-NW catalysts changed while the electrochemical potential was lowered to negatives values, from 1.0 to 0.3 V versus RHE. The Pt/O region in the in situ Fourier transforms remained the same as the potentials were applied, suggesting an alloy formation between Pt and Ni, and Pt/Pt contracted in the presence of Ni. These results provide a better understanding of PtNi-NWs in alkaline electrolytes, suggesting that they are active catalysts for ORR and can be tuned for fuel cell studies.
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Affiliation(s)
- Joesene Soto-Pérez
- Department
of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan 00925-2537, Puerto Rico
| | - Luis E. Betancourt
- Chemistry
Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Pedro Trinidad
- Department
of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan 00925-2537, Puerto Rico
| | - Eduardo Larios
- Departamento
de Ingeniería Química y Metalurgia, Universidad de Sonora, Hermosillo 83000, Mexico
| | - Arnulfo Rojas-Pérez
- Department
of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan 00925-2537, Puerto Rico
| | - Gerardo Quintana
- Department
of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan 00925-2537, Puerto Rico
| | - Kotaro Sasaki
- Chemistry
Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Christopher J. Pollock
- Cornell
High Energy Synchrotron Source (CHESS), Wilson Laboratory, Cornell University, Ithaca, New York 14853, United Sates
| | - Louise M. Debefve
- Cornell
High Energy Synchrotron Source (CHESS), Wilson Laboratory, Cornell University, Ithaca, New York 14853, United Sates
| | - Carlos R. Cabrera
- Department
of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan 00925-2537, Puerto Rico
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15
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Gallagher CA, Chudzinska M, Larsen-Gray A, Pollock CJ, Sells SN, White PJC, Berger U. From theory to practice in pattern-oriented modelling: identifying and using empirical patterns in predictive models. Biol Rev Camb Philos Soc 2021; 96:1868-1888. [PMID: 33978325 DOI: 10.1111/brv.12729] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 04/14/2021] [Accepted: 04/16/2021] [Indexed: 01/21/2023]
Abstract
To robustly predict the effects of disturbance and ecosystem changes on species, it is necessary to produce structurally realistic models with high predictive power and flexibility. To ensure that these models reflect the natural conditions necessary for reliable prediction, models must be informed and tested using relevant empirical observations. Pattern-oriented modelling (POM) offers a systematic framework for employing empirical patterns throughout the modelling process and has been coupled with complex systems modelling, such as in agent-based models (ABMs). However, while the production of ABMs has been rising rapidly, the explicit use of POM has not increased. Challenges with identifying patterns and an absence of specific guidelines on how to implement empirical observations may limit the accessibility of POM and lead to the production of models which lack a systematic consideration of reality. This review serves to provide guidance on how to identify and apply patterns following a POM approach in ABMs (POM-ABMs), specifically addressing: where in the ecological hierarchy can we find patterns; what kinds of patterns are useful; how should simulations and observations be compared; and when in the modelling cycle are patterns used? The guidance and examples provided herein are intended to encourage the application of POM and inspire efficient identification and implementation of patterns for both new and experienced modellers alike. Additionally, by generalising patterns found especially useful for POM-ABM development, these guidelines provide practical help for the identification of data gaps and guide the collection of observations useful for the development and verification of predictive models. Improving the accessibility and explicitness of POM could facilitate the production of robust and structurally realistic models in the ecological community, contributing to the advancement of predictive ecology at large.
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Affiliation(s)
- Cara A Gallagher
- Department of Plant Ecology and Conservation Biology, University of Potsdam, Am Mühlenberg 3, Potsdam, 14469, Germany.,Department of Bioscience, Aarhus University, Frederiksborgvej 399, Roskilde, 4000
| | - Magda Chudzinska
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, KY16 9ST, U.K
| | - Angela Larsen-Gray
- Department of Integrative Biology, University of Wisconsin-Madison, 250 N. Mills St., Madison, WI, 53706, U.S.A
| | | | - Sarah N Sells
- Montana Cooperative Wildlife Research Unit, The University of Montana, 205 Natural Sciences, Missoula, MT, 59812, U.S.A
| | - Patrick J C White
- School of Applied Sciences, Edinburgh Napier University, 9 Sighthill Ct., Edinburgh, EH11 4BN, U.K
| | - Uta Berger
- Institute of Forest Growth and Computer Science, Technische Universität Dresden, Dresden, 01062, Germany
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16
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Lane JV, Jeavons R, Deakin Z, Sherley RB, Pollock CJ, Wanless RJ, Hamer KC. Vulnerability of northern gannets to offshore wind farms; seasonal and sex-specific collision risk and demographic consequences. Mar Environ Res 2020; 162:105196. [PMID: 33126111 DOI: 10.1016/j.marenvres.2020.105196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/13/2020] [Accepted: 10/14/2020] [Indexed: 06/11/2023]
Abstract
There is a pressing need to quantify the risks of renewable energy developments such as offshore wind farms for protected populations. However, assessments are often based on incomplete data, or fail to consider variation in risk between sexes and at different times of year. We tracked northern gannets foraging from the world's largest colony (Bass Rock, Scotland) across five consecutive breeding seasons. We examine how seasonal and sex differences in behaviour affect the collision risk from planned and operational wind farms within their foraging range and assess the likely consequences for long-term population viability. Both sexes made shorter trips during chick-rearing than prior to chick-hatching, spent a greater proportion of time within wind farm sites and had an eight times greater potential collision risk during chick-rearing. Females made longer trips than males at both these times of year, flew higher and spent more time within wind farm sites, leading to three times greater collision risk for females. After accounting for the potential additional mortality from collisions, and assuming that the death of a parent also led to the loss of its offspring, the breeding population was projected to increase by 3.57% (95% CI: 2.16-5.15%) per year, compared with 6.56% (95% CI: 4.59-8.73%) in the absence of turbines, suggesting a negligible effect on population viability. However, additional mortality could result in greater immigration from neighbouring colonies, potentially affecting their viability and highlighting a need for research within a metapopulation framework to assess the impacts of offshore wind developments on vulnerable species across multiple connected sites.
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Affiliation(s)
- Jude V Lane
- School of Biology, University of Leeds, Leeds, UK.
| | - Ruth Jeavons
- School of Biology, University of Leeds, Leeds, UK
| | - Zoe Deakin
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Richard B Sherley
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
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17
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Greener MS, Hutton E, Pollock CJ, Wilson A, Lam CY, Nokhbatolfoghahai M, Jowers MJ, Downie JR. Correction: Sexual dichromatism in the neotropical genus Mannophryne (Anura: Aromobatidae). PLoS One 2020; 15:e0238962. [PMID: 32881932 PMCID: PMC7470393 DOI: 10.1371/journal.pone.0238962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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18
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Greener MS, Hutton E, Pollock CJ, Wilson A, Lam CY, Nokhbatolfoghahai M, Jowers MJ, Downie JR. Sexual dichromatism in the neotropical genus Mannophryne (Anura: Aromobatidae). PLoS One 2020; 15:e0223080. [PMID: 32639962 PMCID: PMC7343140 DOI: 10.1371/journal.pone.0223080] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 05/30/2020] [Indexed: 11/18/2022] Open
Abstract
Recent reviews on sexual dichromatism in frogs included Mannophryne trinitatis as the only example they could find of dynamic dichromatism (males turn black when calling) within the family Aromobatidae and found no example of ontogenetic dichromatism in this group. We demonstrate ontogenetic dichromatism in M. trinitatis by rearing post-metamorphic froglets to near maturity: the throats of all individuals started as grey coloured; at around seven weeks, the throat became pale yellow in some, and more strongly yellow as development proceeded; the throats of adults are grey in males and variably bright yellow in females, backed by a dark collar. We demonstrated the degree of throat colour variability by analysing a large sample of females. The red: green (R:G) ratio ranged from ~1.1 to 1.4, reflecting variation from yellow to yellow/orange, and there was also variation in the tone and width of the dark collar, and in the extent to which the yellow colouration occurred posterior to the collar. Female M. trinitatis are known to be territorial in behaviour. We show a positive relationship between throat colour (R:G ratio) and escape performance, as a proxy for quality. Our field observations on Tobago’s M. olmonae showed variability in female throat colour and confirmed that males in this species also turn black when calling. Our literature review of the 20 Mannophryne species so far named showed that all females have yellow throats with dark collars, and that male colour change to black when calling has been reported in eight species; in the remaining 12 species, descriptions of males calling are usually lacking so far. We predict that both dynamic and ontogenetic sexual dichromatism are universal in this genus and provide discussion of the ecological role of dichromatism in this genus of predominantly diurnal, non-toxic frogs, with strong paternal care of offspring.
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Affiliation(s)
- Mark S. Greener
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
- * E-mail:
| | - Emily Hutton
- School of Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Christopher J. Pollock
- School of Biology, Faculty of Biological sciences, University of Leeds, Leeds, United Kingdom
| | - Annabeth Wilson
- School of Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Chun Yin Lam
- School of Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | | | - Michael J. Jowers
- CIBIO/InBIO (Centro de Investigacao em Biodiversidade e Recursos Genticos), Universide do Porto, Vairao, Portugal
| | - J. Roger Downie
- School of Life Sciences, University of Glasgow, Glasgow, United Kingdom
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Kimura KW, Casebolt R, Cimada DaSilva J, Kauffman E, Kim J, Dunbar TA, Pollock CJ, Suntivich J, Hanrath T. Selective Electrochemical CO2 Reduction during Pulsed Potential Stems from Dynamic Interface. ACS Catal 2020. [DOI: 10.1021/acscatal.0c02630] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kevin W. Kimura
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Rileigh Casebolt
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Jessica Cimada DaSilva
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Elyse Kauffman
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Jiyoon Kim
- Material Science & Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Tyler A. Dunbar
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Christopher J. Pollock
- Cornell High Energy Synchrotron Source (CHESS), Wilson Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Jin Suntivich
- Material Science & Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Tobias Hanrath
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
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20
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Pan J, Wenger ES, Matthews ML, Pollock CJ, Bhardwaj M, Kim AJ, Allen BD, Grossman RB, Krebs C, Bollinger JM. Evidence for Modulation of Oxygen Rebound Rate in Control of Outcome by Iron(II)- and 2-Oxoglutarate-Dependent Oxygenases. J Am Chem Soc 2019; 141:15153-15165. [PMID: 31475820 DOI: 10.1021/jacs.9b06689] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenases generate iron(IV)-oxo (ferryl) intermediates that can abstract hydrogen from aliphatic carbons (R-H). Hydroxylation proceeds by coupling of the resultant substrate radical (R•) and oxygen of the Fe(III)-OH complex ("oxygen rebound"). Nonhydroxylation outcomes result from different fates of the Fe(III)-OH/R• state; for example, halogenation results from R• coupling to a halogen ligand cis to the hydroxide. We previously suggested that halogenases control substrate-cofactor disposition to disfavor oxygen rebound and permit halogen coupling to prevail. Here, we explored the general implication that, when a ferryl intermediate can ambiguously target two substrate carbons for different outcomes, rebound to the site capable of the alternative outcome should be slower than to the adjacent, solely hydroxylated site. We evaluated this prediction for (i) the halogenase SyrB2, which exclusively hydroxylates C5 of norvaline appended to its carrier protein but can either chlorinate or hydroxylate C4 and (ii) two bifunctional enzymes that normally hydroxylate one carbon before coupling that oxygen to a second carbon (producing an oxacycle) but can, upon encountering deuterium at the first site, hydroxylate the second site instead. In all three cases, substrate hydroxylation incorporates a greater fraction of solvent-derived oxygen at the site that can also undergo the alternative outcome than at the other site, most likely reflecting an increased exchange of the initially O2-derived oxygen ligand in the longer-lived Fe(III)-OH/R• states. Suppression of rebound may thus be generally important for nonhydroxylation outcomes by these enzymes.
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Affiliation(s)
| | | | | | | | - Minakshi Bhardwaj
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40546-0312 , United States
| | | | | | - Robert B Grossman
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40546-0312 , United States
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21
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Parashar TN, Chasapis A, Bandyopadhyay R, Chhiber R, Matthaeus WH, Maruca B, Shay MA, Burch JL, Moore TE, Giles BL, Gershman DJ, Pollock CJ, Torbert RB, Russell CT, Strangeway RJ, Roytershteyn V. Kinetic Range Spectral Features of Cross Helicity Using the Magnetospheric Multiscale Spacecraft. Phys Rev Lett 2018; 121:265101. [PMID: 30636132 DOI: 10.1103/physrevlett.121.265101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 10/21/2018] [Indexed: 06/09/2023]
Abstract
We study spectral features of ion velocity and magnetic field correlations in the magnetosheath and in the solar wind using data from the Magnetospheric Multiscale (MMS) spacecraft. High-resolution MMS observations enable the study of the transition of these correlations between their magnetofluid character at larger scales into the subproton kinetic range, previously unstudied in spacecraft data. Cross-helicity, angular alignment, and energy partitioning is examined over a suitable range of scales, employing measurements based on the Taylor frozen-in approximation as well as direct two-spacecraft correlation measurements. The results demonstrate signatures of alignment at large scales. As kinetic scales are approached, the alignment between v and b is destroyed by demagnetization of protons.
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Affiliation(s)
- Tulasi N Parashar
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - Alexandros Chasapis
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - Riddhi Bandyopadhyay
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - Rohit Chhiber
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - W H Matthaeus
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - B Maruca
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - M A Shay
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - J L Burch
- Southwest Research Institute, San Antonio 78238-5166, Texas, USA
| | - T E Moore
- NASA Goddard Space Flight Center, Greenbelt 20771, Maryland, USA
| | - B L Giles
- NASA Goddard Space Flight Center, Greenbelt 20771, Maryland, USA
| | - D J Gershman
- NASA Goddard Space Flight Center, Greenbelt 20771, Maryland, USA
| | - C J Pollock
- Denali Scientific, Fairbanks 99709, Alaska, USA
| | - R B Torbert
- University of New Hampshire, Durham 03824, New Hampshire, USA
| | - C T Russell
- University of California, Los Angeles 90095-1567, California, USA
| | - R J Strangeway
- University of California, Los Angeles 90095-1567, California, USA
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22
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Torbert RB, Burch JL, Phan TD, Hesse M, Argall MR, Shuster J, Ergun RE, Alm L, Nakamura R, Genestreti KJ, Gershman DJ, Paterson WR, Turner DL, Cohen I, Giles BL, Pollock CJ, Wang S, Chen LJ, Stawarz JE, Eastwood JP, Hwang KJ, Farrugia C, Dors I, Vaith H, Mouikis C, Ardakani A, Mauk BH, Fuselier SA, Russell CT, Strangeway RJ, Moore TE, Drake JF, Shay MA, Khotyaintsev YV, Lindqvist PA, Baumjohann W, Wilder FD, Ahmadi N, Dorelli JC, Avanov LA, Oka M, Baker DN, Fennell JF, Blake JB, Jaynes AN, Le Contel O, Petrinec SM, Lavraud B, Saito Y. Electron-scale dynamics of the diffusion region during symmetric magnetic reconnection in space. Science 2018; 362:1391-1395. [PMID: 30442767 DOI: 10.1126/science.aat2998] [Citation(s) in RCA: 158] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 11/06/2018] [Indexed: 11/02/2022]
Abstract
Magnetic reconnection is an energy conversion process that occurs in many astrophysical contexts including Earth's magnetosphere, where the process can be investigated in situ by spacecraft. On 11 July 2017, the four Magnetospheric Multiscale spacecraft encountered a reconnection site in Earth's magnetotail, where reconnection involves symmetric inflow conditions. The electron-scale plasma measurements revealed (i) super-Alfvénic electron jets reaching 15,000 kilometers per second; (ii) electron meandering motion and acceleration by the electric field, producing multiple crescent-shaped structures in the velocity distributions; and (iii) the spatial dimensions of the electron diffusion region with an aspect ratio of 0.1 to 0.2, consistent with fast reconnection. The well-structured multiple layers of electron populations indicate that the dominant electron dynamics are mostly laminar, despite the presence of turbulence near the reconnection site.
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Affiliation(s)
- R B Torbert
- University of New Hampshire, Durham, NH, USA. .,Southwest Research Institute (SwRI), San Antonio, TX, USA
| | - J L Burch
- Southwest Research Institute (SwRI), San Antonio, TX, USA
| | - T D Phan
- University of California, Berkeley, CA, USA
| | - M Hesse
- Southwest Research Institute (SwRI), San Antonio, TX, USA.,University of Bergen, Bergen, Norway
| | - M R Argall
- University of New Hampshire, Durham, NH, USA
| | - J Shuster
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - R E Ergun
- University of Colorado Laboratory for Atmospheric and Space Physics, Boulder, CO, USA
| | - L Alm
- Swedish Institute of Space Physics, Uppsala, Sweden
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - K J Genestreti
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - D J Gershman
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - W R Paterson
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - D L Turner
- Aerospace Corporation, El Segundo, CA, USA
| | - I Cohen
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - B L Giles
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - C J Pollock
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - S Wang
- University of Maryland, College Park, MD, USA
| | - L-J Chen
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,University of Maryland, College Park, MD, USA
| | - J E Stawarz
- Blackett Laboratory, Imperial College London, London, UK
| | - J P Eastwood
- Blackett Laboratory, Imperial College London, London, UK
| | - K J Hwang
- Southwest Research Institute (SwRI), San Antonio, TX, USA
| | - C Farrugia
- University of New Hampshire, Durham, NH, USA
| | - I Dors
- University of New Hampshire, Durham, NH, USA
| | - H Vaith
- University of New Hampshire, Durham, NH, USA
| | - C Mouikis
- University of New Hampshire, Durham, NH, USA
| | - A Ardakani
- University of New Hampshire, Durham, NH, USA
| | - B H Mauk
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - S A Fuselier
- Southwest Research Institute (SwRI), San Antonio, TX, USA.,University of Texas, San Antonio, TX, USA
| | - C T Russell
- University of California, Los Angeles, CA, USA
| | | | - T E Moore
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - J F Drake
- University of Maryland, College Park, MD, USA
| | - M A Shay
- University of Delaware, Newark, DE, USA
| | | | | | - W Baumjohann
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - F D Wilder
- University of Colorado Laboratory for Atmospheric and Space Physics, Boulder, CO, USA
| | - N Ahmadi
- University of Colorado Laboratory for Atmospheric and Space Physics, Boulder, CO, USA
| | - J C Dorelli
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - L A Avanov
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - M Oka
- University of California, Berkeley, CA, USA
| | - D N Baker
- University of Colorado Laboratory for Atmospheric and Space Physics, Boulder, CO, USA
| | | | - J B Blake
- Aerospace Corporation, El Segundo, CA, USA
| | | | - O Le Contel
- Laboratoire de Physique des Plasmas, CNRS/Ecole Polytechnique/Sorbonne Université/Univ. Paris Sud/Observatoire de Paris, Paris, France
| | - S M Petrinec
- Lockheed Martin Advanced Technology Center, Palo Alto, CA, USA
| | - B Lavraud
- Institut de Recherche en Astrophysique et Planétologie, CNRS, Centre National d'Etudes Spatiales, Université de Toulouse, Toulouse, France
| | - Y Saito
- Institute for Space and Astronautical Sciences, Sagamihara, Japan
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23
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Martinie RJ, Blaesi EJ, Bollinger JM, Krebs C, Finkelstein KD, Pollock CJ. Two-Color Valence-to-Core X-ray Emission Spectroscopy Tracks Cofactor Protonation State in a Class I Ribonucleotide Reductase. Angew Chem Int Ed Engl 2018; 57:12754-12758. [PMID: 30075052 PMCID: PMC6579043 DOI: 10.1002/anie.201807366] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 07/20/2018] [Indexed: 12/20/2022]
Abstract
Proton transfer reactions are of central importance to a wide variety of biochemical processes, though determining proton location and monitoring proton transfers in biological systems is often extremely challenging. Herein, we use two-color valence-to-core X-ray emission spectroscopy (VtC XES) to identify protonation events across three oxidation states of the O2 -activating, radical-initiating manganese-iron heterodinuclear cofactor in a class I-c ribonucleotide reductase. This is the first application of VtC XES to an enzyme intermediate and the first simultaneous measurement of two-color VtC spectra. In contrast to more conventional methods of assessing protonation state, VtC XES is a more direct probe applicable to a wide range of metalloenzyme systems. These data, coupled to insight provided by DFT calculations, allow the inorganic cores of the MnIV FeIV and MnIV FeIII states of the enzyme to be assigned as MnIV (μ-O)2 FeIV and MnIV (μ-O)(μ-OH)FeIII , respectively.
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Affiliation(s)
- Ryan J Martinie
- Department of Chemistry, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
| | - Elizabeth J Blaesi
- Department of Chemistry, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
| | - J Martin Bollinger
- Department of Chemistry and Department of Biochemistry and Molecular Biology, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
| | - Carsten Krebs
- Department of Chemistry and Department of Biochemistry and Molecular Biology, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
| | - Kenneth D Finkelstein
- Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, NY, 14853, USA
| | - Christopher J Pollock
- Department of Chemistry, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
- Present address: Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, NY, 14853, USA
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24
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Martinie RJ, Blaesi EJ, Bollinger JM, Krebs C, Finkelstein KD, Pollock CJ. Two‐Color Valence‐to‐Core X‐ray Emission Spectroscopy Tracks Cofactor Protonation State in a Class I Ribonucleotide Reductase. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201807366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ryan J. Martinie
- Department of Chemistry The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
| | - Elizabeth J. Blaesi
- Department of Chemistry The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
| | - J. Martin Bollinger
- Department of Chemistry and Department of Biochemistry and Molecular Biology The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
| | - Carsten Krebs
- Department of Chemistry and Department of Biochemistry and Molecular Biology The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
| | - Kenneth D. Finkelstein
- Cornell High Energy Synchrotron Source, Wilson Laboratory Cornell University Ithaca NY 14853 USA
| | - Christopher J. Pollock
- Department of Chemistry The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
- Present address: Cornell High Energy Synchrotron Source Wilson Laboratory Cornell University Ithaca NY 14853 USA
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25
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Kitamura N, Kitahara M, Shoji M, Miyoshi Y, Hasegawa H, Nakamura S, Katoh Y, Saito Y, Yokota S, Gershman DJ, Vinas AF, Giles BL, Moore TE, Paterson WR, Pollock CJ, Russell CT, Strangeway RJ, Fuselier SA, Burch JL. Direct measurements of two-way wave-particle energy transfer in a collisionless space plasma. Science 2018; 361:1000-1003. [PMID: 30190400 DOI: 10.1126/science.aap8730] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 07/04/2018] [Indexed: 11/02/2022]
Abstract
Particle acceleration by plasma waves and spontaneous wave generation are fundamental energy and momentum exchange processes in collisionless plasmas. Such wave-particle interactions occur ubiquitously in space. We present ultrafast measurements in Earth's magnetosphere by the Magnetospheric Multiscale spacecraft that enabled quantitative evaluation of energy transfer in interactions associated with electromagnetic ion cyclotron waves. The observed ion distributions are not symmetric around the magnetic field direction but are in phase with the plasma wave fields. The wave-ion phase relations demonstrate that a cyclotron resonance transferred energy from hot protons to waves, which in turn nonresonantly accelerated cold He+ to energies up to ~2 kilo-electron volts. These observations provide direct quantitative evidence for collisionless energy transfer in plasmas between distinct particle populations via wave-particle interactions.
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Affiliation(s)
- N Kitamura
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan. .,Department of Earth and Planetary Science, Graduate School of Science, the University of Tokyo, Tokyo, Japan
| | - M Kitahara
- Department of Geophysics, Graduate School of Science, Tohoku University, Sendai, Japan
| | - M Shoji
- Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Nagoya, Japan
| | - Y Miyoshi
- Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Nagoya, Japan
| | - H Hasegawa
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - S Nakamura
- Research Institute for Sustainable Humanosphere (RISH), Kyoto University, Uji, Japan
| | - Y Katoh
- Department of Geophysics, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Y Saito
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - S Yokota
- Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - D J Gershman
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - A F Vinas
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,Department of Physics, American University, Washington, DC, USA
| | - B L Giles
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - T E Moore
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - W R Paterson
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | | | - C T Russell
- Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA, USA
| | - R J Strangeway
- Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA, USA
| | - S A Fuselier
- Southwest Research Institute, San Antonio, TX, USA.,University of Texas at San Antonio, San Antonio, TX, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, TX, USA
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26
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Rose HR, Ghosh MK, Maggiolo AO, Pollock CJ, Blaesi EJ, Hajj V, Wei Y, Rajakovich LJ, Chang WC, Han Y, Hajj M, Krebs C, Silakov A, Pandelia ME, Bollinger JM, Boal AK. Structural Basis for Superoxide Activation of Flavobacterium johnsoniae Class I Ribonucleotide Reductase and for Radical Initiation by Its Dimanganese Cofactor. Biochemistry 2018; 57:2679-2693. [PMID: 29609464 DOI: 10.1021/acs.biochem.8b00247] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A ribonucleotide reductase (RNR) from Flavobacterium johnsoniae ( Fj) differs fundamentally from known (subclass a-c) class I RNRs, warranting its assignment to a new subclass, Id. Its β subunit shares with Ib counterparts the requirements for manganese(II) and superoxide (O2-) for activation, but it does not require the O2--supplying flavoprotein (NrdI) needed in Ib systems, instead scavenging the oxidant from solution. Although Fj β has tyrosine at the appropriate sequence position (Tyr 104), this residue is not oxidized to a radical upon activation, as occurs in the Ia/b proteins. Rather, Fj β directly deploys an oxidized dimanganese cofactor for radical initiation. In treatment with one-electron reductants, the cofactor can undergo cooperative three-electron reduction to the II/II state, in contrast to the quantitative univalent reduction to inactive "met" (III/III) forms seen with I(a-c) βs. This tendency makes Fj β unusually robust, as the II/II form can readily be reactivated. The structure of the protein rationalizes its distinctive traits. A distortion in a core helix of the ferritin-like architecture renders the active site unusually open, introduces a cavity near the cofactor, and positions a subclass-d-specific Lys residue to shepherd O2- to the Mn2II/II cluster. Relative to the positions of the radical tyrosines in the Ia/b proteins, the unreactive Tyr 104 of Fj β is held away from the cofactor by a hydrogen bond with a subclass-d-specific Thr residue. Structural comparisons, considered with its uniquely simple mode of activation, suggest that the Id protein might most closely resemble the primordial RNR-β.
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Affiliation(s)
| | | | | | | | | | | | - Yifeng Wei
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | | | | | | | | | | | | | - Maria-Eirini Pandelia
- Department of Biochemistry , Brandeis University , Waltham , Massachusetts 02454 , United States
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27
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Martinie RJ, Pollock CJ, Matthews ML, Bollinger JM, Krebs C, Silakov A. Vanadyl as a Stable Structural Mimic of Reactive Ferryl Intermediates in Mononuclear Nonheme-Iron Enzymes. Inorg Chem 2017; 56:13382-13389. [PMID: 28960972 DOI: 10.1021/acs.inorgchem.7b02113] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The iron(II)- and 2-(oxo)glutarate-dependent (Fe/2OG) oxygenases catalyze an array of challenging transformations via a common iron(IV)-oxo (ferryl) intermediate, which in most cases abstracts hydrogen (H•) from an aliphatic carbon of the substrate. Although it has been shown that the relative disposition of the Fe-O and C-H bonds can control the rate of H• abstraction and fate of the resultant substrate radical, there remains a paucity of structural information on the actual ferryl states, owing to their high reactivity. We demonstrate here that the stable vanadyl ion [(VIV-oxo)2+] binds along with 2OG or its decarboxylation product, succinate, in the active site of two different Fe/2OG enzymes to faithfully mimic their transient ferryl states. Both ferryl and vanadyl complexes of the Fe/2OG halogenase, SyrB2, remain stably bound to its carrier protein substrate (l-aminoacyl-S-SyrB1), whereas the corresponding complexes harboring transition metals (Fe, Mn) in lower oxidation states dissociate. In the well-studied taurine:2OG dioxygenase (TauD), the disposition of the substrate C-H bond relative to the vanadyl ion defined by pulse electron paramagnetic resonance methods is consistent with the crystal structure of the reactant complex and computational models of the ferryl state. Vanadyl substitution may thus afford access to structural details of the key ferryl intermediates in this important enzyme class.
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Affiliation(s)
| | | | - Megan L Matthews
- Department of Chemical Physiology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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28
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Mitchell AJ, Dunham NP, Martinie RJ, Bergman JA, Pollock CJ, Hu K, Allen BD, Chang WC, Silakov A, Bollinger JM, Krebs C, Boal AK. Visualizing the Reaction Cycle in an Iron(II)- and 2-(Oxo)-glutarate-Dependent Hydroxylase. J Am Chem Soc 2017; 139:13830-13836. [PMID: 28823155 DOI: 10.1021/jacs.7b07374] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Iron(II)- and 2-(oxo)-glutarate-dependent oxygenases catalyze diverse oxidative transformations that are often initiated by abstraction of hydrogen from carbon by iron(IV)-oxo (ferryl) complexes. Control of the relative orientation of the substrate C-H and ferryl Fe-O bonds, primarily by direction of the oxo group into one of two cis-related coordination sites (termed inline and offline), may be generally important for control of the reaction outcome. Neither the ferryl complexes nor their fleeting precursors have been crystallographically characterized, hindering direct experimental validation of the offline hypothesis and elucidation of the means by which the protein might dictate an alternative oxo position. Comparison of high-resolution X-ray crystal structures of the substrate complex, an Fe(II)-peroxysuccinate ferryl precursor, and a vanadium(IV)-oxo mimic of the ferryl intermediate in the l-arginine 3-hydroxylase, VioC, reveals coordinated motions of active site residues that appear to control the intermediate geometries to determine reaction outcome.
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Affiliation(s)
- Andrew J Mitchell
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Noah P Dunham
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Ryan J Martinie
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Jonathan A Bergman
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Christopher J Pollock
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Kai Hu
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.,The Huck Institutes for the Life Sciences, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Benjamin D Allen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.,The Huck Institutes for the Life Sciences, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Wei-Chen Chang
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Alexey Silakov
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - J Martin Bollinger
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.,Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Carsten Krebs
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.,Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Amie K Boal
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.,Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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29
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Zhou M, Berchem J, Walker RJ, El-Alaoui M, Deng X, Cazzola E, Lapenta G, Goldstein ML, Paterson WR, Pang Y, Ergun RE, Lavraud B, Liang H, Russell CT, Strangeway RJ, Zhao C, Giles BL, Pollock CJ, Lindqvist PA, Marklund G, Wilder FD, Khotyaintsev YV, Torbert RB, Burch JL. Coalescence of Macroscopic Flux Ropes at the Subsolar Magnetopause: Magnetospheric Multiscale Observations. Phys Rev Lett 2017; 119:055101. [PMID: 28949734 DOI: 10.1103/physrevlett.119.055101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Indexed: 06/07/2023]
Abstract
We report unambiguous in situ observation of the coalescence of macroscopic flux ropes by the magnetospheric multiscale (MMS) mission. Two coalescing flux ropes with sizes of ∼1 R_{E} were identified at the subsolar magnetopause by the occurrence of an asymmetric quadrupolar signature in the normal component of the magnetic field measured by the MMS spacecraft. An electron diffusion region (EDR) with a width of four local electron inertial lengths was embedded within the merging current sheet. The EDR was characterized by an intense parallel electric field, significant energy dissipation, and suprathermal electrons. Although the electrons were organized by a large guide field, the small observed electron pressure nongyrotropy may be sufficient to support a significant fraction of the parallel electric field within the EDR. Since the flux ropes are observed in the exhaust region, we suggest that secondary EDRs are formed further downstream of the primary reconnection line between the magnetosheath and magnetospheric fields.
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Affiliation(s)
- M Zhou
- Department of Physics and Astronomy, UCLA, Los Angeles 90095, California, USA
| | - J Berchem
- Department of Physics and Astronomy, UCLA, Los Angeles 90095, California, USA
| | - R J Walker
- Department of Earth, Planetary, and Space Sciences, UCLA, Los Angeles 90095, California, USA
| | - M El-Alaoui
- Department of Physics and Astronomy, UCLA, Los Angeles 90095, California, USA
| | - X Deng
- Nanchang University, Nanchang 330031, People's Republic of China
| | - E Cazzola
- Centre for Plasma Astrophysics, Department of Mathematics, Katholieke Universiteit, Leuven 3001, Belgium
| | - G Lapenta
- Centre for Plasma Astrophysics, Department of Mathematics, Katholieke Universiteit, Leuven 3001, Belgium
| | - M L Goldstein
- NASA, Goddard Space Flight Center, Greenbelt 20771, Maryland, USA
- Space Science Institute, Boulder 80301, Colorado, USA
| | - W R Paterson
- NASA, Goddard Space Flight Center, Greenbelt 20771, Maryland, USA
| | - Y Pang
- Nanchang University, Nanchang 330031, People's Republic of China
| | - R E Ergun
- University of Colorado LASP, Boulder 80303, Colorado, USA
| | - B Lavraud
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, UPS, CNES, Toulouse 31028, France
| | - H Liang
- Department of Physics and Astronomy, UCLA, Los Angeles 90095, California, USA
| | - C T Russell
- Department of Earth, Planetary, and Space Sciences, UCLA, Los Angeles 90095, California, USA
| | - R J Strangeway
- Department of Earth, Planetary, and Space Sciences, UCLA, Los Angeles 90095, California, USA
| | - C Zhao
- Department of Earth, Planetary, and Space Sciences, UCLA, Los Angeles 90095, California, USA
| | - B L Giles
- NASA, Goddard Space Flight Center, Greenbelt 20771, Maryland, USA
| | - C J Pollock
- NASA, Goddard Space Flight Center, Greenbelt 20771, Maryland, USA
| | - P-A Lindqvist
- Royal Institute of Technology, Stockholm SE-11428, Sweden
| | - G Marklund
- Royal Institute of Technology, Stockholm SE-11428, Sweden
| | - F D Wilder
- University of Colorado LASP, Boulder 80303, Colorado, USA
| | | | - R B Torbert
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - J L Burch
- Southwest Research Institute, San Antonio Texas 78238, USA
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30
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Capilla-Lasheras P, Dominoni DM, Babayan SA, O'Shaughnessy PJ, Mladenova M, Woodford L, Pollock CJ, Barr T, Baldini F, Helm B. Elevated Immune Gene Expression Is Associated with Poor Reproductive Success of Urban Blue Tits. Front Ecol Evol 2017. [DOI: 10.3389/fevo.2017.00064] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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31
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Russell CT, Strangeway RJ, Zhao C, Anderson BJ, Baumjohann W, Bromund KR, Fischer D, Kepko L, Le G, Magnes W, Nakamura R, Plaschke F, Slavin JA, Torbert RB, Moore TE, Paterson WR, Pollock CJ, Burch JL. Structure, force balance, and topology of Earth's magnetopause. Science 2017; 356:960-963. [PMID: 28572393 DOI: 10.1126/science.aag3112] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 01/25/2017] [Accepted: 05/12/2017] [Indexed: 11/02/2022]
Abstract
The magnetopause deflects the solar wind plasma and confines Earth's magnetic field. We combine measurements made by the four spacecraft of the Magnetospheric Multiscale mission to demonstrate how the plasma and magnetic forces at the boundary affect the interaction between the shocked solar wind and Earth's magnetosphere. We compare these forces with the plasma pressure and examine the electron distribution function. We find that the magnetopause has sublayers with thickness comparable to the ion scale. Small pockets of low magnetic field strength, small radius of curvature, and high electric current mark the electron diffusion region. The flow of electrons, parallel and antiparallel to the magnetic field, reveals a complex topology with the creation of magnetic ropes at the boundary.
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Affiliation(s)
- C T Russell
- Earth Planetary and Space Sciences, University of California, Los Angeles, CA 90095, USA.
| | - R J Strangeway
- Earth Planetary and Space Sciences, University of California, Los Angeles, CA 90095, USA
| | - C Zhao
- Earth Planetary and Space Sciences, University of California, Los Angeles, CA 90095, USA
| | - B J Anderson
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723-6099, USA
| | - W Baumjohann
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8010 Graz, Austria
| | - K R Bromund
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - D Fischer
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8010 Graz, Austria
| | - L Kepko
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.,University of New Hampshire, Durham, NH 03824, USA
| | - G Le
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - W Magnes
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8010 Graz, Austria
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8010 Graz, Austria
| | - F Plaschke
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8010 Graz, Austria
| | - J A Slavin
- Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109-2143, USA
| | - R B Torbert
- University of New Hampshire, Durham, NH 03824, USA
| | - T E Moore
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - W R Paterson
- Earth Planetary and Space Sciences, University of California, Los Angeles, CA 90095, USA
| | - C J Pollock
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, TX 78228-0510, USA
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32
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Fuller FD, Gul S, Chatterjee R, Burgie ES, Young ID, Lebrette H, Srinivas V, Brewster AS, Michels-Clark T, Clinger JA, Andi B, Ibrahim M, Pastor E, de Lichtenberg C, Hussein R, Pollock CJ, Zhang M, Stan CA, Kroll T, Fransson T, Weninger C, Kubin M, Aller P, Lassalle L, Bräuer P, Miller MD, Amin M, Koroidov S, Roessler CG, Allaire M, Sierra RG, Docker PT, Glownia JM, Nelson S, Koglin JE, Zhu D, Chollet M, Song S, Lemke H, Liang M, Sokaras D, Alonso-Mori R, Zouni A, Messinger J, Bergmann U, Boal AK, Bollinger JM, Krebs C, Högbom M, Phillips GN, Vierstra RD, Sauter NK, Orville AM, Kern J, Yachandra VK, Yano J. Drop-on-demand sample delivery for studying biocatalysts in action at X-ray free-electron lasers. Nat Methods 2017; 14:443-449. [PMID: 28250468 DOI: 10.1038/nmeth.4195] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 01/18/2017] [Indexed: 12/22/2022]
Abstract
X-ray crystallography at X-ray free-electron laser sources is a powerful method for studying macromolecules at biologically relevant temperatures. Moreover, when combined with complementary techniques like X-ray emission spectroscopy, both global structures and chemical properties of metalloenzymes can be obtained concurrently, providing insights into the interplay between the protein structure and dynamics and the chemistry at an active site. The implementation of such a multimodal approach can be compromised by conflicting requirements to optimize each individual method. In particular, the method used for sample delivery greatly affects the data quality. We present here a robust way of delivering controlled sample amounts on demand using acoustic droplet ejection coupled with a conveyor belt drive that is optimized for crystallography and spectroscopy measurements of photochemical and chemical reactions over a wide range of time scales. Studies with photosystem II, the phytochrome photoreceptor, and ribonucleotide reductase R2 illustrate the power and versatility of this method.
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Affiliation(s)
- Franklin D Fuller
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Sheraz Gul
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Ruchira Chatterjee
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - E Sethe Burgie
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Iris D Young
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Hugo Lebrette
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Vivek Srinivas
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Aaron S Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Tara Michels-Clark
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | | | - Babak Andi
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York, USA
| | - Mohamed Ibrahim
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Ernest Pastor
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | | | - Rana Hussein
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Christopher J Pollock
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Miao Zhang
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Claudiu A Stan
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Thomas Kroll
- SSRL, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Thomas Fransson
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Clemens Weninger
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California, USA.,LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Markus Kubin
- Institute for Methods and Instrumentation on Synchrotron Radiation Research, Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
| | - Pierre Aller
- Diamond Light Source Limited, Harwell Science and Innovation Campus, Didcot, UK
| | - Louise Lassalle
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Philipp Bräuer
- Diamond Light Source Limited, Harwell Science and Innovation Campus, Didcot, UK.,Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Muhamed Amin
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Sergey Koroidov
- Institutionen för Kemi, Kemiskt Biologiskt Centrum, Umeå Universitet, Umeå, Sweden.,Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Christian G Roessler
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York, USA
| | - Marc Allaire
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Raymond G Sierra
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Peter T Docker
- Diamond Light Source Limited, Harwell Science and Innovation Campus, Didcot, UK
| | - James M Glownia
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Silke Nelson
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Jason E Koglin
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Diling Zhu
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Matthieu Chollet
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Sanghoon Song
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Henrik Lemke
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Mengning Liang
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | | | | | - Athina Zouni
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Johannes Messinger
- Institutionen för Kemi, Kemiskt Biologiskt Centrum, Umeå Universitet, Umeå, Sweden.,Department of Chemistry-Ångström, Molecular Biomimetics, Uppsala University, Uppsala, Sweden
| | - Uwe Bergmann
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Amie K Boal
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, USA.,Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, USA
| | - J Martin Bollinger
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, USA.,Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Carsten Krebs
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, USA.,Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Martin Högbom
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.,Department of Chemistry, Stanford University, Stanford, California, USA
| | - George N Phillips
- Department of BioSciences, Rice University, Houston, Texas, USA.,Department of Chemistry, Rice University, Houston, Texas, USA
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Nicholas K Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Allen M Orville
- Diamond Light Source Limited, Harwell Science and Innovation Campus, Didcot, UK
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA.,LCLS, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Vittal K Yachandra
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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33
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Martinie RJ, Blaesi EJ, Krebs C, Bollinger JM, Silakov A, Pollock CJ. Evidence for a Di-μ-oxo Diamond Core in the Mn(IV)/Fe(IV) Activation Intermediate of Ribonucleotide Reductase from Chlamydia trachomatis. J Am Chem Soc 2017; 139:1950-1957. [PMID: 28075562 DOI: 10.1021/jacs.6b11563] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
High-valent iron and manganese complexes effect some of the most challenging biochemical reactions known, including hydrocarbon and water oxidations associated with the global carbon cycle and oxygenic photosynthesis, respectively. Their extreme reactivity presents an impediment to structural characterization, but their biological importance and potential chemical utility have, nevertheless, motivated extensive efforts toward that end. Several such intermediates accumulate during activation of class I ribonucleotide reductase (RNR) β subunits, which self-assemble dimetal cofactors with stable one-electron oxidants that serve to initiate the enzyme's free-radical mechanism. In the class I-c β subunit from Chlamydia trachomatis, a heterodinuclear Mn(II)/Fe(II) complex reacts with dioxygen to form a Mn(IV)/Fe(IV) intermediate, which undergoes reduction of the iron site to produce the active Mn(IV)/Fe(III) cofactor. Herein, we assess the structure of the Mn(IV)/Fe(IV) activation intermediate using Fe- and Mn-edge extended X-ray absorption fine structure (EXAFS) analysis and multifrequency pulse electron paramagnetic resonance (EPR) spectroscopy. The EXAFS results reveal a metal-metal vector of 2.74-2.75 Å and an intense light-atom (C/N/O) scattering interaction 1.8 Å from the Fe. Pulse EPR data reveal an exchangeable deuterium hyperfine coupling of strength |T| = 0.7 MHz, but no stronger couplings. The results suggest that the intermediate possesses a di-μ-oxo diamond core structure with a terminal hydroxide ligand to the Mn(IV).
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Affiliation(s)
- Ryan J Martinie
- Department of Chemistry and ‡Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Elizabeth J Blaesi
- Department of Chemistry and ‡Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Carsten Krebs
- Department of Chemistry and ‡Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - J Martin Bollinger
- Department of Chemistry and ‡Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Alexey Silakov
- Department of Chemistry and ‡Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Christopher J Pollock
- Department of Chemistry and ‡Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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34
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Johlander A, Schwartz SJ, Vaivads A, Khotyaintsev YV, Gingell I, Peng IB, Markidis S, Lindqvist PA, Ergun RE, Marklund GT, Plaschke F, Magnes W, Strangeway RJ, Russell CT, Wei H, Torbert RB, Paterson WR, Gershman DJ, Dorelli JC, Avanov LA, Lavraud B, Saito Y, Giles BL, Pollock CJ, Burch JL. Rippled Quasiperpendicular Shock Observed by the Magnetospheric Multiscale Spacecraft. Phys Rev Lett 2016; 117:165101. [PMID: 27792387 DOI: 10.1103/physrevlett.117.165101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 06/06/2023]
Abstract
Collisionless shock nonstationarity arising from microscale physics influences shock structure and particle acceleration mechanisms. Nonstationarity has been difficult to quantify due to the small spatial and temporal scales. We use the closely spaced (subgyroscale), high-time-resolution measurements from one rapid crossing of Earth's quasiperpendicular bow shock by the Magnetospheric Multiscale (MMS) spacecraft to compare competing nonstationarity processes. Using MMS's high-cadence kinetic plasma measurements, we show that the shock exhibits nonstationarity in the form of ripples.
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Affiliation(s)
- A Johlander
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
- Department of Physics and Astronomy, Uppsala University, Uppsala 75120, Sweden
| | - S J Schwartz
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
- Laboratory of Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - A Vaivads
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | | | - I Gingell
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - I B Peng
- KTH Royal Institute of Technology, Stockholm 11428, Sweden
| | - S Markidis
- KTH Royal Institute of Technology, Stockholm 11428, Sweden
| | - P-A Lindqvist
- KTH Royal Institute of Technology, Stockholm 11428, Sweden
| | - R E Ergun
- Laboratory of Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - G T Marklund
- KTH Royal Institute of Technology, Stockholm 11428, Sweden
| | - F Plaschke
- Space Research Institute, Austrian Academy of Sciences, Graz 8042, Austria
| | - W Magnes
- Space Research Institute, Austrian Academy of Sciences, Graz 8042, Austria
| | - R J Strangeway
- University of California, Los Angeles, California 90095, USA
| | - C T Russell
- University of California, Los Angeles, California 90095, USA
| | - H Wei
- University of California, Los Angeles, California 90095, USA
| | - R B Torbert
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - W R Paterson
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - D J Gershman
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
- University of Maryland, College Park, Maryland 20742, USA
| | - J C Dorelli
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - L A Avanov
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - B Lavraud
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Toulouse 31028, France
- Centre National de la Recherche Scientifique, UMR 5277, Toulouse 31400, France
| | - Y Saito
- Institute of Space and Astronautical Science, JAXA, Sagamihara 2525210, Japan
| | - B L Giles
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - C J Pollock
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, Texas 78238, USA
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35
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Sahu S, Zhang B, Pollock CJ, Dürr M, Davies CG, Confer AM, Ivanović-Burmazović I, Siegler MA, Jameson GNL, Krebs C, Goldberg DP. Aromatic C-F Hydroxylation by Nonheme Iron(IV)-Oxo Complexes: Structural, Spectroscopic, and Mechanistic Investigations. J Am Chem Soc 2016; 138:12791-12802. [PMID: 27656776 PMCID: PMC5628738 DOI: 10.1021/jacs.6b03346] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The synthesis and reactivity of a series of mononuclear nonheme iron complexes that carry out intramolecular aromatic C-F hydroxylation reactions is reported. The key intermediate prior to C-F hydroxylation, [FeIV(O)(N4Py2Ar1)](BF4)2 (1-O, Ar1 = -2,6-difluorophenyl), was characterized by single-crystal X-ray diffraction. The crystal structure revealed a nonbonding C-H···O═Fe interaction with a CH3CN molecule. Variable-field Mössbauer spectroscopy of 1-O indicates an intermediate-spin (S = 1) ground state. The Mössbauer parameters for 1-O include an unusually small quadrupole splitting for a triplet FeIV(O) and are reproduced well by density functional theory calculations. With the aim of investigating the initial step for C-F hydroxylation, two new ligands were synthesized, N4Py2Ar2 (L2, Ar2 = -2,6-difluoro-4-methoxyphenyl) and N4Py2Ar3 (L3, Ar3 = -2,6-difluoro-3-methoxyphenyl), with -OMe substituents in the meta or ortho/para positions with respect to the C-F bonds. FeII complexes [Fe(N4Py2Ar2)(CH3CN)](ClO4)2 (2) and [Fe(N4Py2Ar3)(CH3CN)](ClO4)2 (3) reacted with isopropyl 2-iodoxybenzoate to give the C-F hydroxylated FeIII-OAr products. The FeIV(O) intermediates 2-O and 3-O were trapped at low temperature and characterized. Complex 2-O displayed a C-F hydroxylation rate similar to that of 1-O. In contrast, the kinetics (via stopped-flow UV-vis) for complex 3-O displayed a significant rate enhancement for C-F hydroxylation. Eyring analysis revealed the activation barriers for the C-F hydroxylation reaction for the three complexes, consistent with the observed difference in reactivity. A terminal FeII(OH) complex (4) was prepared independently to investigate the possibility of a nucleophilic aromatic substitution pathway, but the stability of 4 rules out this mechanism. Taken together the data fully support an electrophilic C-F hydroxylation mechanism.
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Affiliation(s)
- Sumit Sahu
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Bo Zhang
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Christopher J. Pollock
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Maximilian Dürr
- Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Casey G. Davies
- Department of Chemistry & MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Alex M. Confer
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | | | - Maxime A. Siegler
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Guy N. L. Jameson
- Department of Chemistry & MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Carsten Krebs
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - David P. Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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36
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Rees JA, Wandzilak A, Maganas D, Wurster NIC, Hugenbruch S, Kowalska JK, Pollock CJ, Lima FA, Finkelstein KD, DeBeer S. Experimental and theoretical correlations between vanadium K-edge X-ray absorption and Kβ emission spectra. J Biol Inorg Chem 2016; 21:793-805. [PMID: 27251139 PMCID: PMC4989026 DOI: 10.1007/s00775-016-1358-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 04/29/2016] [Indexed: 11/28/2022]
Abstract
A series of vanadium compounds was studied by K-edge X-ray absorption (XAS) and K[Formula: see text] X-ray emission spectroscopies (XES). Qualitative trends within the datasets, as well as comparisons between the XAS and XES data, illustrate the information content of both methods. The complementary nature of the chemical insight highlights the success of this dual-technique approach in characterizing both the structural and electronic properties of vanadium sites. In particular, and in contrast to XAS or extended X-ray absorption fine structure (EXAFS), we demonstrate that valence-to-core XES is capable of differentiating between ligating atoms with the same identity but different bonding character. Finally, density functional theory (DFT) and time-dependent DFT calculations enable a more detailed, quantitative interpretation of the data. We also establish correction factors for the computational protocols through calibration to experiment. These hard X-ray methods can probe vanadium ions in any oxidation or spin state, and can readily be applied to sample environments ranging from solid-phase catalysts to biological samples in frozen solution. Thus, the combined XAS and XES approach, coupled with DFT calculations, provides a robust tool for the study of vanadium atoms in bioinorganic chemistry.
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Affiliation(s)
- Julian A Rees
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Aleksandra Wandzilak
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059, Kraków, Poland
| | - Dimitrios Maganas
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Nicole I C Wurster
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Stefan Hugenbruch
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Joanna K Kowalska
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Christopher J Pollock
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Frederico A Lima
- Centro Nacional de Pesquisa em Energia e Materiais, Laboratório Nacional de Luz Síncrotron, Rua Giuseppe Máximo Scolfaro 10000, Campinas, SP, 13083-970, Brazil
| | - Kenneth D Finkelstein
- Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, NY, 14853, USA
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany.
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
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37
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Hill JL, Hardy NF, Jimenez DV, Maynard KR, Kardian AS, Pollock CJ, Schloesser RJ, Martinowich K. Loss of promoter IV-driven BDNF expression impacts oscillatory activity during sleep, sensory information processing and fear regulation. Transl Psychiatry 2016; 6:e873. [PMID: 27552586 PMCID: PMC5022093 DOI: 10.1038/tp.2016.153] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 06/23/2016] [Indexed: 11/09/2022] Open
Abstract
Posttraumatic stress disorder is characterized by hyperarousal, sensory processing impairments, sleep disturbances and altered fear regulation; phenotypes associated with changes in brain oscillatory activity. Molecules associated with activity-dependent plasticity, including brain-derived neurotrophic factor (BDNF), may regulate neural oscillations by controlling synaptic activity. BDNF synthesis includes production of multiple Bdnf transcripts, which contain distinct 5' noncoding exons. We assessed arousal, sensory processing, fear regulation and sleep in animals where BDNF expression from activity-dependent promoter IV is disrupted (Bdnf-e4 mice). Bdnf-e4 mice display sensory hyper-reactivity and impaired electrophysiological correlates of sensory information processing as measured by event-related potentials (ERP). Utilizing electroencephalogram, we identified a decrease in slow-wave activity during non-rapid eye movement sleep, suggesting impaired sleep homeostasis. Fear extinction is controlled by hippocampal-prefrontal cortical BDNF signaling, and neurophysiological communication patterns between the hippocampus (HPC) and medial prefrontal cortex (mPFC) correlate with behavioral performance during extinction. Impaired fear extinction in Bdnf-e4 mice is accompanied by increased HPC activation and decreased HPC-mPFC theta phase synchrony during early extinction, as well as increased mPFC activation during extinction recall. These results suggest that activity-dependent BDNF signaling is critical for regulating oscillatory activity, which may contribute to altered behavior.
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Affiliation(s)
- J L Hill
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, USA
| | - N F Hardy
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, USA
| | - D V Jimenez
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, USA
| | - K R Maynard
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, USA
| | - A S Kardian
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, USA
| | - C J Pollock
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, USA
| | - R J Schloesser
- Sheppard Pratt-Lieber Research Institute, Inc., Baltimore, MD, USA
| | - K Martinowich
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, USA,Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA,Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA,Lieber Institute for Brain Development, 855 North Wolfe Street, 347B, Suite 300, Baltimore, MD 21205, USA. E-mail:
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38
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Eriksson S, Wilder FD, Ergun RE, Schwartz SJ, Cassak PA, Burch JL, Chen LJ, Torbert RB, Phan TD, Lavraud B, Goodrich KA, Holmes JC, Stawarz JE, Sturner AP, Malaspina DM, Usanova ME, Trattner KJ, Strangeway RJ, Russell CT, Pollock CJ, Giles BL, Hesse M, Lindqvist PA, Drake JF, Shay MA, Nakamura R, Marklund GT. Magnetospheric Multiscale Observations of the Electron Diffusion Region of Large Guide Field Magnetic Reconnection. Phys Rev Lett 2016; 117:015001. [PMID: 27419573 DOI: 10.1103/physrevlett.117.015001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Indexed: 06/06/2023]
Abstract
We report observations from the Magnetospheric Multiscale (MMS) satellites of a large guide field magnetic reconnection event. The observations suggest that two of the four MMS spacecraft sampled the electron diffusion region, whereas the other two spacecraft detected the exhaust jet from the event. The guide magnetic field amplitude is approximately 4 times that of the reconnecting field. The event is accompanied by a significant parallel electric field (E_{∥}) that is larger than predicted by simulations. The high-speed (∼300 km/s) crossing of the electron diffusion region limited the data set to one complete electron distribution inside of the electron diffusion region, which shows significant parallel heating. The data suggest that E_{∥} is balanced by a combination of electron inertia and a parallel gradient of the gyrotropic electron pressure.
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Affiliation(s)
- S Eriksson
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - F D Wilder
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - R E Ergun
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - S J Schwartz
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- The Blackett Laboratory, Imperial College, London SW7 2AZ, United Kingdom
| | - P A Cassak
- West Virginia University, Morgantown, West Virginia 26506, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, Texas 78238-5166, USA
| | - L-J Chen
- University of Maryland, College Park, Maryland 20742, USA
| | - R B Torbert
- Southwest Research Institute, San Antonio, Texas 78238-5166, USA
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - T D Phan
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - B Lavraud
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, 31028 Toulouse, France
- Centre National de la Recherche Scientifique, UMR 5277, Toulouse, France
| | - K A Goodrich
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - J C Holmes
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - J E Stawarz
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - A P Sturner
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - D M Malaspina
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - M E Usanova
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - K J Trattner
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - R J Strangeway
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - C T Russell
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - C J Pollock
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - B L Giles
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - M Hesse
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - P-A Lindqvist
- KTH Royal Institute of Technology, SE-11428 Stockholm, Sweden
| | - J F Drake
- University of Maryland, College Park, Maryland 20742, USA
| | - M A Shay
- University of Delaware, Newark, Delaware 19716, USA
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, 8042 Graz, Austria
| | - G T Marklund
- KTH Royal Institute of Technology, SE-11428 Stockholm, Sweden
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Ergun RE, Goodrich KA, Wilder FD, Holmes JC, Stawarz JE, Eriksson S, Sturner AP, Malaspina DM, Usanova ME, Torbert RB, Lindqvist PA, Khotyaintsev Y, Burch JL, Strangeway RJ, Russell CT, Pollock CJ, Giles BL, Hesse M, Chen LJ, Lapenta G, Goldman MV, Newman DL, Schwartz SJ, Eastwood JP, Phan TD, Mozer FS, Drake J, Shay MA, Cassak PA, Nakamura R, Marklund G. Magnetospheric Multiscale Satellites Observations of Parallel Electric Fields Associated with Magnetic Reconnection. Phys Rev Lett 2016; 116:235102. [PMID: 27341241 DOI: 10.1103/physrevlett.116.235102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Indexed: 06/06/2023]
Abstract
We report observations from the Magnetospheric Multiscale satellites of parallel electric fields (E_{∥}) associated with magnetic reconnection in the subsolar region of the Earth's magnetopause. E_{∥} events near the electron diffusion region have amplitudes on the order of 100 mV/m, which are significantly larger than those predicted for an antiparallel reconnection electric field. This Letter addresses specific types of E_{∥} events, which appear as large-amplitude, near unipolar spikes that are associated with tangled, reconnected magnetic fields. These E_{∥} events are primarily in or near a current layer near the separatrix and are interpreted to be double layers that may be responsible for secondary reconnection in tangled magnetic fields or flux ropes. These results are telling of the three-dimensional nature of magnetopause reconnection and indicate that magnetopause reconnection may be often patchy and/or drive turbulence along the separatrix that results in flux ropes and/or tangled magnetic fields.
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Affiliation(s)
- R E Ergun
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - K A Goodrich
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - F D Wilder
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - J C Holmes
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - J E Stawarz
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - S Eriksson
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - A P Sturner
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - D M Malaspina
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - M E Usanova
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - R B Torbert
- University of New Hampshire, Durham, New Hampshire 03824, USA
- Southwest Research Institute, San Antonio, Texas 78238, USA
| | - P-A Lindqvist
- KTH Royal Institute of Technology, Stockholm, Sweden
| | - Y Khotyaintsev
- Swedish Institute of Space Physics (Uppsala), Uppsala, Sweden
| | - J L Burch
- Southwest Research Institute, San Antonio, Texas 78238, USA
| | - R J Strangeway
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - C T Russell
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - C J Pollock
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - B L Giles
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - M Hesse
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - L J Chen
- University of Maryland, College Park, Maryland 20742, USA
| | - G Lapenta
- Leuven Universiteit, Leuven, Belgium
| | - M V Goldman
- Department of Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - D L Newman
- Department of Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - S J Schwartz
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
- The Blackett Laboratory, Imperial College London, United Kingdom
| | - J P Eastwood
- The Blackett Laboratory, Imperial College London, United Kingdom
| | - T D Phan
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - F S Mozer
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - J Drake
- University of Maryland, College Park, Maryland 20742, USA
| | - M A Shay
- University of Delaware, Newark, Delaware 19716, USA
| | - P A Cassak
- West Virginia University, Morgantown, West Virginia 26506, USA
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - G Marklund
- KTH Royal Institute of Technology, Stockholm, Sweden
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Burch JL, Torbert RB, Phan TD, Chen LJ, Moore TE, Ergun RE, Eastwood JP, Gershman DJ, Cassak PA, Argall MR, Wang S, Hesse M, Pollock CJ, Giles BL, Nakamura R, Mauk BH, Fuselier SA, Russell CT, Strangeway RJ, Drake JF, Shay MA, Khotyaintsev YV, Lindqvist PA, Marklund G, Wilder FD, Young DT, Torkar K, Goldstein J, Dorelli JC, Avanov LA, Oka M, Baker DN, Jaynes AN, Goodrich KA, Cohen IJ, Turner DL, Fennell JF, Blake JB, Clemmons J, Goldman M, Newman D, Petrinec SM, Trattner KJ, Lavraud B, Reiff PH, Baumjohann W, Magnes W, Steller M, Lewis W, Saito Y, Coffey V, Chandler M. Electron-scale measurements of magnetic reconnection in space. Science 2016; 352:aaf2939. [PMID: 27174677 DOI: 10.1126/science.aaf2939] [Citation(s) in RCA: 438] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/03/2016] [Indexed: 11/02/2022]
Abstract
Magnetic reconnection is a fundamental physical process in plasmas whereby stored magnetic energy is converted into heat and kinetic energy of charged particles. Reconnection occurs in many astrophysical plasma environments and in laboratory plasmas. Using measurements with very high time resolution, NASA's Magnetospheric Multiscale (MMS) mission has found direct evidence for electron demagnetization and acceleration at sites along the sunward boundary of Earth's magnetosphere where the interplanetary magnetic field reconnects with the terrestrial magnetic field. We have (i) observed the conversion of magnetic energy to particle energy; (ii) measured the electric field and current, which together cause the dissipation of magnetic energy; and (iii) identified the electron population that carries the current as a result of demagnetization and acceleration within the reconnection diffusion/dissipation region.
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Affiliation(s)
- J L Burch
- Southwest Research Institute, San Antonio, TX, USA.
| | - R B Torbert
- Southwest Research Institute, San Antonio, TX, USA. University of New Hampshire, Durham, NH, USA
| | - T D Phan
- University of California, Berkeley, CA, USA
| | - L-J Chen
- University of Maryland, College Park, MD, USA
| | - T E Moore
- NASA, Goddard Space Flight Center, Greenbelt, MD, USA
| | - R E Ergun
- University of Colorado LASP, Boulder, CO, USA
| | - J P Eastwood
- Blackett Laboratory, Imperial College London, London, UK
| | - D J Gershman
- NASA, Goddard Space Flight Center, Greenbelt, MD, USA
| | - P A Cassak
- West Virginia University, Morgantown, WV, USA
| | - M R Argall
- University of New Hampshire, Durham, NH, USA
| | - S Wang
- University of Maryland, College Park, MD, USA
| | - M Hesse
- NASA, Goddard Space Flight Center, Greenbelt, MD, USA
| | - C J Pollock
- NASA, Goddard Space Flight Center, Greenbelt, MD, USA
| | - B L Giles
- NASA, Goddard Space Flight Center, Greenbelt, MD, USA
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - B H Mauk
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - S A Fuselier
- Southwest Research Institute, San Antonio, TX, USA
| | - C T Russell
- University of California, Los Angeles, CA, USA
| | | | - J F Drake
- University of Maryland, College Park, MD, USA
| | - M A Shay
- University of Delaware, Newark, DE, USA
| | | | | | - G Marklund
- Royal Institute of Technology, Stockholm, Sweden
| | - F D Wilder
- University of Colorado LASP, Boulder, CO, USA
| | - D T Young
- Southwest Research Institute, San Antonio, TX, USA
| | - K Torkar
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - J Goldstein
- Southwest Research Institute, San Antonio, TX, USA
| | - J C Dorelli
- NASA, Goddard Space Flight Center, Greenbelt, MD, USA
| | - L A Avanov
- NASA, Goddard Space Flight Center, Greenbelt, MD, USA
| | - M Oka
- University of California, Berkeley, CA, USA
| | - D N Baker
- University of Colorado LASP, Boulder, CO, USA
| | - A N Jaynes
- University of Colorado LASP, Boulder, CO, USA
| | | | - I J Cohen
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - D L Turner
- Aerospace Corporation, El Segundo, CA, USA
| | | | - J B Blake
- Aerospace Corporation, El Segundo, CA, USA
| | - J Clemmons
- Aerospace Corporation, El Segundo, CA, USA
| | - M Goldman
- University of Colorado, Boulder, CO, USA
| | - D Newman
- University of Colorado, Boulder, CO, USA
| | - S M Petrinec
- Lockheed Martin Advanced Technology Center, Palo Alto, CA, USA
| | | | - B Lavraud
- Institut de Recherche en Astrophysique et Planétologie, Toulouse, France
| | - P H Reiff
- Department of Physics and Astronomy, Rice University, Houston, TX, USA
| | - W Baumjohann
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - W Magnes
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - M Steller
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - W Lewis
- Southwest Research Institute, San Antonio, TX, USA
| | - Y Saito
- Institute for Space and Astronautical Sciences, Sagamihara, Japan
| | - V Coffey
- NASA, Marshall Space Flight Center, Huntsville, AL, USA
| | - M Chandler
- NASA, Marshall Space Flight Center, Huntsville, AL, USA
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de Moraes MG, de Carvalho MAM, Franco AC, Pollock CJ, Figueiredo-Ribeiro R. Fire and Drought: Soluble Carbohydrate Storage and Survival Mechanisms in Herbaceous Plants from the Cerrado. Bioscience 2016. [DOI: 10.1093/biosci/biv178] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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Pollock CJ, DeBeer S. Insights into the geometric and electronic structure of transition metal centers from valence-to-core X-ray emission spectroscopy. Acc Chem Res 2015; 48:2967-75. [PMID: 26401686 DOI: 10.1021/acs.accounts.5b00309] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A long-standing goal of inorganic chemists is the ability to decipher the geometric and electronic structures of chemical species. This is particularly true for the study of small molecule and biological catalysts, where this knowledge is critical for understanding how these molecules effect chemical transformations. Numerous techniques are available for this task, and collectively they have enabled detailed understanding of many complex chemical systems. Despite this battery of probes, however, challenges still remain, particularly when the structural question involves subtle perturbations of the ligands bound to a metal center, as is often the case during chemical reactions. It is here that, as an emerging probe of chemical structure, valence-to-core (VtC) X-ray emission spectroscopy (XES) holds promise. VtC XES begins with ionization of a 1s electron from a metal ion by high energy X-ray photons. Electrons residing in ligand-localized valence orbitals decay to fill the 1s hole, emitting fluorescent photons in the process; in this manner, VtC XES primarily probes the filled, ligand-based orbitals of a metal complex. This is in contrast to other X-ray based techniques, such as K-edge X-ray absorption and EXAFS, which probe the unoccupied d-manifold orbitals and atomic scatterers surrounding the metal, respectively. As a hard X-ray technique, VtC XES experiments can be performed on a variety of sample states and environments, enabling application to demanding systems, such as high pressure cells and dilute biological samples. VtC XES thus can offer unique insights into the geometric and electronic structures of inorganic complexes. In recent years, we have sought to use VtC XES in the study of inorganic and bioinorganic complexes; doing so, however, first required a thorough and detailed understanding of the information content of these spectra. Extensive experimental surveys of model compounds coupled to the insights provided by DFT calculated spectra of real and hypothetical compounds allowed the development of a framework whereby VtC XES spectra may be understood in terms of a molecular orbital picture. Specifically, VtC spectra may be interpreted as a probe of electronic structure for the ligands bound to a metal center, enabling access to chemical information that can be difficult to obtain with other methods. Examples of this include the ability to (1) assess the identity and number of atomic/small molecule ligands bound to a metal center, (2) quantify the degree of bond activation of a small molecule substrate, and (3) establish the protonation state of donor atoms. With this foundation established, VtC has been meaningfully applied to long-standing questions in bioinorganic chemistry, with the potential for numerous future applications in all areas of metal-mediated catalysis.
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Affiliation(s)
- Christopher J. Pollock
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Serena DeBeer
- Max-Planck-Institute
for Chemical Energy Conversion, Stiftstrasse
34-36, D-45470 Mülheim
an der Ruhr, Germany
- Department
of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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Nokhbatolfoghahai M, Pollock CJ, Downie JR. Oviposition and development in the glass frog Hyalinobatrachium orientale (Anura: Centrolenidae). Phyllomedusa 2015. [DOI: 10.11606/issn.2316-9079.v14i1p3-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Oviposition and development in the glass frog Hyalinobatrachium orientale (Anura: Centrolenidae). Oviposition and external embryonic developmental features are described in the Tobago glass frog, Hyalinobatrachium orientale. Egg clutches are nearly always laid on the undersides of leaves (one exception); usually leaves of Heliconia sp. are used, but Philodendron and palms may be used in the absence of Heliconia. Clutches contain 28.0 ± 5.3 eggs (mean ± SD) and eggs are 1.86 ± 0.11 mm in diameter. The behavior of one amplectant pair was followed for more than five hours; the pair rotated several times around a small area of the leaf depositing eggs in a tight spiral formation. External embryonic features were observed by scanning electron microscopy. Surface ciliation is extensive up to the time of hatching when it is lost; external gills are short and a cement gland is absent. Hatching gland cells were detectable on the anterodorsal surface of the head from Day 4 after deposition and persisted until at least Day 10, and hatching occurred between Days 9 and 16. During this period, progressive development in tail length, surface pigmentation, intestinal coiling, and oral disc features was observed. Post-hatching larvae reared for six weeks grew 37% in length and tripled in weight, but remained at Gosner Stage 25.
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Gennari M, Brazzolotto D, Pécaut J, Cherrier MV, Pollock CJ, DeBeer S, Retegan M, Pantazis DA, Neese F, Rouzières M, Clérac R, Duboc C. Dioxygen Activation and Catalytic Reduction to Hydrogen Peroxide by a Thiolate-Bridged Dimanganese(II) Complex with a Pendant Thiol. J Am Chem Soc 2015; 137:8644-53. [DOI: 10.1021/jacs.5b04917] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Marcello Gennari
- CNRS
UMR 5250, DCM, Université Grenoble Alpes, F-38000 Grenoble, France
| | | | - Jacques Pécaut
- INAC-SCIB, Université Grenoble Alpes, F-38000 Grenoble, France
- Reconnaissance Ionique et Chimie de Coordination, CEA, INAC-SCIB, F-38000 Grenoble, France
| | - Mickael V. Cherrier
- Metalloproteins
Unit, Institut de Biologie Structurale Jean-Pierre Ebel, CEA, CNRS
UMR 5075, Université Grenoble Alpes, 41 rue Horowitz, 38027 Grenoble Cedex 1, France
- Université de Lyon, F-69622 Lyon, France
- Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France
- CNRS,
UMR 5086 Bases Moléculaires et Structurales de Systèmes
Infectieux, Institut de Biologie et Chimie des Protéines, 7 Passage du Vercors, F-69367 Lyon, France
| | - Christopher J. Pollock
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- Department
of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Marius Retegan
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Mathieu Rouzières
- CNRS, CRPP, UPR 8641, F-33600 Pessac, France
- CRPP,
UPR 8641, Université Bordeaux, F-33600 Pessac, France
| | - Rodolphe Clérac
- CNRS, CRPP, UPR 8641, F-33600 Pessac, France
- CRPP,
UPR 8641, Université Bordeaux, F-33600 Pessac, France
| | - Carole Duboc
- CNRS
UMR 5250, DCM, Université Grenoble Alpes, F-38000 Grenoble, France
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Abstract
Transition-metal Kβ X-ray emission spectroscopy (XES) is a developing technique that probes the occupied molecular orbitals of a metal complex. As an element-specific probe of metal centers, Kβ XES is finding increasing applications in catalytic and, in particular, bioinorganic systems. For the continued development of XES as a probe of these complex systems, however, the full range of factors which contribute to XES spectral modulations must be explored. In this report, an investigation of a series of oxo-bridged iron dimers reveals that the intensity of valence-to-core features is sensitive to the Fe-O-Fe bond angle. The intensity of these features has a well-known dependence on metal-ligand bond distance, but a dependence upon bond angle has not previously been documented. Herein, we explore the angular dependence of valence-to-core XES features both experimentally and computationally. Taken together, these results show that, as the Fe-O-Fe angle decreases, the intensity of the Kβ″ feature increases and that this effect is modulated by increasing amounts of Fe np mixing into the O 2s orbital at smaller bond angles. The relevance of these findings to the identification of oxygenated intermediates in bioinorganic systems is highlighted, with special emphasis given to the case of soluble methane monooxygenase.
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Affiliation(s)
- Christopher J Pollock
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
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46
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Hall ER, Pollock CJ, Bendix J, Collins TJ, Glatzel P, DeBeer S. Valence-to-Core-Detected X-ray Absorption Spectroscopy: Targeting Ligand Selectivity. J Am Chem Soc 2014; 136:10076-84. [DOI: 10.1021/ja504206y] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Eleanor R. Hall
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- Department
of Chemistry, University of Oxford, Oxford OX1 2JD, United Kingdom
| | - Christopher J. Pollock
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Jesper Bendix
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Terrence J. Collins
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Pieter Glatzel
- European
Synchrotron Radiation Facility, 71 Rue des Martyrs, 38000 Grenoble, France
| | - Serena DeBeer
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- Department
of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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Pollock CJ, Tan LL, Zhang W, Lancaster KM, Lee SC, DeBeer S. Light-Atom Influences on the Electronic Structures of Iron–Sulfur Clusters. Inorg Chem 2014; 53:2591-7. [DOI: 10.1021/ic402944r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Christopher J. Pollock
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Lay Ling Tan
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L3G1
| | - Wei Zhang
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L3G1
| | - Kyle M. Lancaster
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Sonny C. Lee
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L3G1
| | - Serena DeBeer
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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Pollock CJ, Hails RS. The case for reforming the EU regulatory system for GMOs. Trends Biotechnol 2014; 32:63-4. [DOI: 10.1016/j.tibtech.2013.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 10/11/2013] [Accepted: 10/18/2013] [Indexed: 11/28/2022]
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Krewald V, Lassalle-Kaiser B, Boron TT, Pollock CJ, Kern J, Beckwith MA, Yachandra VK, Pecoraro VL, Yano J, Neese F, DeBeer S. The protonation states of oxo-bridged Mn(IV) dimers resolved by experimental and computational Mn K pre-edge X-ray absorption spectroscopy. Inorg Chem 2013; 52:12904-14. [PMID: 24161030 PMCID: PMC3911776 DOI: 10.1021/ic4008203] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In nature, the protonation of oxo bridges is a commonly encountered mechanism for fine-tuning chemical properties and reaction pathways. Often, however, the protonation states are difficult to establish experimentally. This is of particular importance in the oxygen evolving complex of photosystem II, where identification of the bridging oxo protonation states is one of the essential requirements toward unraveling the mechanism. In order to establish a combined experimental and theoretical protocol for the determination of protonation states, we have systematically investigated a series of Mn model complexes by Mn K pre-edge X-ray absorption spectroscopy. An ideal test case for selective bis-μ-oxo-bridge protonation in a Mn dimer is represented by the system [Mn(IV)2(salpn)2(μ-OHn)2](n+). Although the three species [Mn(IV)2(salpn)2(μ-O)2], [Mn(IV)2(salpn)2(μ-O)(μ-OH)](+) and [Mn(IV)2(salpn)2(μ-OH)2](2+) differ only in the protonation of the oxo bridges, they exhibit distinct differences in the pre-edge region while maintaining the same edge energy. The experimental spectra are correlated in detail to theoretically calculated spectra. A time-dependent density functional theory approach for calculating the pre-edge spectra of molecules with multiple metal centers is presented, using both high spin (HS) and broken symmetry (BS) electronic structure solutions. The most intense pre-edge transitions correspond to an excitation of the Mn 1s core electrons into the unoccupied orbitals of local e(g) character (d(z)(2) and d(xy) based in the chosen coordinate system). The lowest energy experimental feature is dominated by excitations of 1s-α electrons, and the second observed feature is primarily attributed to 1s-β electron excitations. The observed energetic separation is due to spin polarization effects in spin-unrestricted density functional theory and models final state multiplet effects. The effects of spin polarization on the calculated Mn K pre-edge spectra, in both the HS and BS solutions, are discussed in terms of the strength of the antiferromagnetic coupling and associated changes in the covalency of Mn-O bonds. The information presented in this paper is complemented with the X-ray emission spectra of the same compounds published in an accompanying paper. Taken together, the two studies provide the foundation for a better understanding of the X-ray spectroscopic data of the oxygen evolving complex (OEC) in photosystem II.
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Affiliation(s)
- Vera Krewald
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Benedikt Lassalle-Kaiser
- Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Thaddeus T. Boron
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Christopher J. Pollock
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Jan Kern
- Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Martha A. Beckwith
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Vittal K. Yachandra
- Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Junko Yano
- Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Frank Neese
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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Pollock CJ, Grubel K, Holland PL, DeBeer S. Experimentally quantifying small-molecule bond activation using valence-to-core X-ray emission spectroscopy. J Am Chem Soc 2013; 135:11803-8. [PMID: 23862983 DOI: 10.1021/ja3116247] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This work establishes the ability of valence-to-core X-ray emission spectroscopy (XES) to serve as a direct probe of N2 bond activation. A systematic series of iron-N2 complexes has been experimentally investigated and the energy of a valence-to-core XES peak was correlated with N-N bond length and stretching frequency. Computations demonstrate that, in a simple one-electron picture, this peak arises from the N2 2s2s σ* orbital, which becomes less antibonding as the N-N bond is weakened and broken. Changes as small as 0.02 Å in the N-N bond length may be distinguished using this approach. The results thus establish valence-to-core XES as an effective probe of small molecule activation, which should have broad applicability in transition-metal mediated catalysis.
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Affiliation(s)
- Christopher J Pollock
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D45470 Mülheim an der Ruhr, Germany
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