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Kawasaki T, Yamaguchi Y, Kitahara H, Irizawa A, Tani M. Exploring Biomolecular Self-Assembly with Far-Infrared Radiation. Biomolecules 2022; 12:biom12091326. [PMID: 36139165 PMCID: PMC9496551 DOI: 10.3390/biom12091326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/13/2022] [Accepted: 09/17/2022] [Indexed: 11/29/2022] Open
Abstract
Physical engineering technology using far-infrared radiation has been gathering attention in chemical, biological, and material research fields. In particular, the high-power radiation at the terahertz region can give remarkable effects on biological materials distinct from a simple thermal treatment. Self-assembly of biological molecules such as amyloid proteins and cellulose fiber plays various roles in medical and biomaterials fields. A common characteristic of those biomolecular aggregates is a sheet-like fibrous structure that is rigid and insoluble in water, and it is often hard to manipulate the stacking conformation without heating, organic solvents, or chemical reagents. We discovered that those fibrous formats can be conformationally regulated by means of intense far-infrared radiations from a free-electron laser and gyrotron. In this review, we would like to show the latest and the past studies on the effects of far-infrared radiation on the fibrous biomaterials and to suggest the potential use of the far-infrared radiation for regulation of the biomolecular self-assembly.
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Affiliation(s)
- Takayasu Kawasaki
- Accelerator Laboratory, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba 305-0801, Ibaraki, Japan
- Correspondence:
| | - Yuusuke Yamaguchi
- Research Center for Development of Far-Infrared Region, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Fukui, Japan
| | - Hideaki Kitahara
- Research Center for Development of Far-Infrared Region, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Fukui, Japan
| | - Akinori Irizawa
- SR Center, Research Organization of Science and Technology, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Shiga, Japan
| | - Masahiko Tani
- Research Center for Development of Far-Infrared Region, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Fukui, Japan
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Anders J, Dreyer F, Krüger D, Schwartz I, Plenio MB, Jelezko F. Progress in miniaturization and low-field nuclear magnetic resonance. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 322:106860. [PMID: 33423757 DOI: 10.1016/j.jmr.2020.106860] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/02/2020] [Accepted: 10/26/2020] [Indexed: 06/12/2023]
Abstract
In this paper, we review the latest developments in miniaturization of NMR systems with an emphasis on low-field NMR. We briefly cover the topics of magnet and coil miniaturization, elaborating on the advantages and disadvantages of miniaturized coils for different applications. The main part of the article is dedicated to progress in NMR electronics. Here, we touch upon software-defined radios as an emerging gadget for NMR before we provide a detailed discussion of NMR-on-a-chip transceivers as the ultimate solution in terms of miniaturization of NMR electronics. In addition to discussing the miniaturization capabilities of the NMR-on-a-chip approach, we also investigate the potential use of NMR-on-a-chip devices for an improved NMR system performance. Here, we also discuss the possibility of combining the NMR-on-a-chip approach with EPR-on-a-chip spectrometers to form compact DNP-on-a-chip systems that can provide a significant sensitivity boost, especially for low-field NMR systems.
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Affiliation(s)
- Jens Anders
- Institute of Smart Sensors, University of Stuttgart, Pfaffenwaldring 47, D-70569 Stuttgart, Germany; Center for Integrated Quantum Science and Technology (IQ(ST)), Germany.
| | - Frederik Dreyer
- Institute of Smart Sensors, University of Stuttgart, Pfaffenwaldring 47, D-70569 Stuttgart, Germany
| | - Daniel Krüger
- Institute of Smart Sensors, University of Stuttgart, Pfaffenwaldring 47, D-70569 Stuttgart, Germany; John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, United States
| | - Ilai Schwartz
- NVision Imaging Technologies GmbH, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Martin B Plenio
- Institute of Theoretical Physics, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany; Center for Integrated Quantum Science and Technology (IQ(ST)), Germany
| | - Fedor Jelezko
- Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11 D-89081 Ulm, Germany; Center for Integrated Quantum Science and Technology (IQ(ST)), Germany
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Reese M, George C, Yang C, Jawla S, Grün JT, Schwalbe H, Redfield C, Temkin RJ, Griffin RG. Modular, triple-resonance, transmission line DNP MAS probe for 500 MHz/330 GHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 307:106573. [PMID: 31505305 PMCID: PMC6766420 DOI: 10.1016/j.jmr.2019.106573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 06/10/2023]
Abstract
We describe the design and construction of a modular, triple-resonance, fully balanced, DNP-MAS probe based on transmission line technology and its integration into a 500 MHz/330 GHz DNP-NMR spectrometer. A novel quantitative probe design and characterization strategy is developed and employed to achieve optimal sensitivity, RF homogeneity and excellent isolation between channels. The resulting three channel HCN probe has a modular design with each individual, swappable module being equipped with connectorized, transmission line ports. This strategy permits attachment of a mating connector that facilitates accurate impedance measurements at these ports and allows characterization and adjustment (e.g. for balancing or tuning/matching) of each component individually. The RF performance of the probe is excellent; for example, the 13C channel attains a Rabi frequency of 280 kHz for a 3.2 mm rotor. In addition, a frequency tunable 330 GHz gyrotron operating at the second harmonic of the electron cyclotron frequency was developed for DNP applications. Careful alignment of the corrugated waveguide led to minimal loss of the microwave power, and an enhancement factor ε = 180 was achieved for U-13C urea in the glassy matrix at 80 K. We demonstrated the operation of the system with acquisition of multidimensional spectra of cross-linked lysozyme crystals which are insoluble in glycerol-water mixtures used for DNP and samples of RNA.
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Affiliation(s)
- Marcel Reese
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Christy George
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Chen Yang
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Sudheer Jawla
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - J Tassilo Grün
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-Universität Frankfurt, 60438 Frankfurt, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-Universität Frankfurt, 60438 Frankfurt, Germany
| | - Christina Redfield
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Richard J Temkin
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Robert G Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
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4
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Lankatillake C, Huynh T, Dias DA. Understanding glycaemic control and current approaches for screening antidiabetic natural products from evidence-based medicinal plants. PLANT METHODS 2019; 15:105. [PMID: 31516543 PMCID: PMC6731622 DOI: 10.1186/s13007-019-0487-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/20/2019] [Indexed: 05/15/2023]
Abstract
Type 2 Diabetes Mellitus has reached epidemic proportions as a result of over-nutrition and increasingly sedentary lifestyles. Current therapies, although effective, are not without limitations. These limitations, the alarming increase in the prevalence of diabetes, and the soaring cost of managing diabetes and its complications underscores an urgent need for safer, more efficient and affordable alternative treatments. Over 1200 plant species are reported in ethnomedicine for treating diabetes and these represents an important and promising source for the identification of novel antidiabetic compounds. Evaluating medicinal plants for desirable bioactivity goes hand-in-hand with methods in analytical biochemistry for separating and identifying lead compounds. This review aims to provide a comprehensive summary of current methods used in antidiabetic plant research to form a useful resource for researchers beginning in the field. The review summarises the current understanding of blood glucose regulation and the general mechanisms of action of current antidiabetic medications, and combines knowledge on common experimental approaches for screening plant extracts for antidiabetic activity and currently available analytical methods and technologies for the separation and identification of bioactive natural products. Common in vivo animal models, in vitro models, in silico methods and biochemical assays used for testing the antidiabetic effects of plants are discussed with a particular emphasis on in vitro methods such as cell-based bioassays for screening insulin secretagogues and insulinomimetics. Enzyme inhibition assays and molecular docking are also highlighted. The role of metabolomics, metabolite profiling, and dereplication of data for the high-throughput discovery of novel antidiabetic agents is reviewed. Finally, this review also summarises sample preparation techniques such as liquid-liquid extraction, solid phase extraction, and supercritical fluid extraction, and the critical function of nuclear magnetic resonance and high resolution liquid chromatography-mass spectrometry for the dereplication, putative identification and structure elucidation of natural compounds from evidence-based medicinal plants.
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Affiliation(s)
- Chintha Lankatillake
- School of Health and Biomedical Sciences, Discipline of Laboratory Medicine, RMIT University, Bundoora, 3083 Australia
| | - Tien Huynh
- School of Science, RMIT University, Bundoora, VIC 3083 Australia
| | - Daniel A. Dias
- School of Health and Biomedical Sciences, Discipline of Laboratory Medicine, RMIT University, Bundoora, 3083 Australia
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5
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Purea A, Reiter C, Dimitriadis AI, de Rijk E, Aussenac F, Sergeyev I, Rosay M, Engelke F. Improved waveguide coupling for 1.3 mm MAS DNP probes at 263 GHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 302:43-49. [PMID: 30953925 DOI: 10.1016/j.jmr.2019.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 06/09/2023]
Abstract
We consider the geometry of a radially irradiated microwave beam in MAS DNP NMR probes and its impact on DNP enhancement. Two related characteristic features are found to be relevant: (i) the focus of the microwave beam on the DNP MAS sample and (ii) the microwave magnetic field magnitude in the sample. We present a waveguide coupler setup that enables us to significantly improve beam focus and field magnitude in 1.3 mm MAS DNP probes at a microwave frequency of 263 GHz, which results in an increase of the DNP enhancement by a factor of 2 compared to previous standard hardware setups. We discuss the implications of improved coupling and its potential to enable cutting-edge applications, such as pulsed high-field DNP and the use of low-power solid-state microwave sources.
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6
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Likhachev A, Danik A, Kovshov Y, Kishko S, Ponomarenko S, Martseniak O, Khutoryan E, Ogawa I, Idehara T, Kuleshov A. Compact radiation module for THz spectroscopy using 300 GHz continuous-wave clinotron. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:034703. [PMID: 30927777 DOI: 10.1063/1.5064796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 02/17/2019] [Indexed: 06/09/2023]
Abstract
The results of the development of compact radiation module based on a 300 GHz continuous-wave (CW) clinotron are presented. The clinotron oscillator is proposed as a part of the module designated for high-field dynamic nuclear polarization (DNP) systems for applications in nuclear magnetic resonance (NMR) spectroscopy. The simulation results of clinotron radiation spectra considering the influence of accelerating voltage pulsations are compared with the requirements for THz radiation linewidth for efficient NMR signal enhancement. Based on the simulations, the 300 GHz CW clinotron oscillator was developed and tested together with the high-voltage (HV) power supply, providing the output voltage stability better than 20 ppm. The frequency stability of 33 ppm was observed during the clinotron operation within several hours. The spectral linewidth is better than 8 MHz at 300 GHz that satisfies the requirements for DNP-NMR spectroscopy.
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Affiliation(s)
- Alexander Likhachev
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine, Kharkiv 61085, Ukraine
| | - Alexander Danik
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine, Kharkiv 61085, Ukraine
| | - Yurii Kovshov
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine, Kharkiv 61085, Ukraine
| | - Sergey Kishko
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine, Kharkiv 61085, Ukraine
| | - Sergey Ponomarenko
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine, Kharkiv 61085, Ukraine
| | | | - Eduard Khutoryan
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine, Kharkiv 61085, Ukraine
| | - Isamu Ogawa
- Research Center for Development of Far-Infrared Region, Fukui University, Fukui 910-8507, Japan
| | - Toshitaka Idehara
- Research Center for Development of Far-Infrared Region, Fukui University, Fukui 910-8507, Japan
| | - Alexei Kuleshov
- O. Ya. Usikov Institute for Radio Physics and Electronics, National Academy of Sciences of Ukraine, Kharkiv 61085, Ukraine
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7
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Fokin A, Glyavin M, Golubiatnikov G, Lubyako L, Morozkin M, Movschevich B, Tsvetkov A, Denisov G. High-power sub-terahertz source with a record frequency stability at up to 1 Hz. Sci Rep 2018. [PMID: 29531359 PMCID: PMC5847556 DOI: 10.1038/s41598-018-22772-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Many state-of-the-art fundamental and industrial projects need the use of terahertz radiation with high power and small linewidth. Gyrotrons as radiation sources provide the desired level of power in the sub-THz and THz frequency range, but have substantial free-running frequency fluctuations of the order of 10−4. Here, we demonstrate that the precise frequency stability of a high-power sub-THz gyrotron can be achieved by a phase-lock loop in the anode voltage control. The relative width of the frequency spectrum and the frequency stability obtained for a 0.263 THz/100 W gyrotron are 4 × 10−12 and 10−10, respectively, and these parameters are better than those demonstrated so far with high-power sources by almost three orders of magnitude. This approach confirms its potential for ultra-high precision spectroscopy, the development of sources with large-scale radiating apertures, and other new projects.
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Affiliation(s)
- Andrey Fokin
- Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Nizhny Novgorod, 603950, Russia.
| | - Mikhail Glyavin
- Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Nizhny Novgorod, 603950, Russia
| | - German Golubiatnikov
- Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Nizhny Novgorod, 603950, Russia
| | - Lev Lubyako
- Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Nizhny Novgorod, 603950, Russia
| | - Mikhail Morozkin
- Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Nizhny Novgorod, 603950, Russia
| | - Boris Movschevich
- Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Nizhny Novgorod, 603950, Russia
| | - Alexander Tsvetkov
- Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Nizhny Novgorod, 603950, Russia
| | - Gregory Denisov
- Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Nizhny Novgorod, 603950, Russia
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8
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Deryugina AV, Oshevenskiy LV, Talamanova MN, Tsvetkov AI, Shabalin MA, Glyavin MY, Krylov VN. Electrokinetic and Biochemical Changes in Erythrocytes under the Action of Terahertz Range Electromagnetic Waves. Biophysics (Nagoya-shi) 2017. [DOI: 10.1134/s0006350917060033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Denisov G, Fokin A, Glyavin M, Golubiatnikov G, Lubyako L, Morozkin M, Movschevich B, Tsvetkov A. High precision frequency stabilization of a 263 GHz continuous wave gyrotron. EPJ WEB OF CONFERENCES 2017. [DOI: 10.1051/epjconf/201714904022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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10
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Rybalko O, Bowen S, Zhurbenko V, Ardenkjær-Larsen JH. Waveguide transition with vacuum window for multiband dynamic nuclear polarization systems. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:054705. [PMID: 27250449 DOI: 10.1063/1.4948294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A low loss waveguide transition section and oversized microwave vacuum window covering several frequency bands (94 GHz, 140 GHz, 188 GHz) is presented. The transition is compact and was optimized for multiband Dynamic Nuclear Polarization (DNP) systems in a full-wave simulator. The window is more broadband than commercially available windows, which are usually optimized for single band operation. It is demonstrated that high-density polyethylene with urethane adhesive can be used as a low loss microwave vacuum window in multiband DNP systems. The overall assembly performance and dimensions are found using full-wave simulations. The practical aspects of the window implementation in the waveguide are discussed. To verify the design and simulation results, the window is tested experimentally at the three frequencies of interest.
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Affiliation(s)
- Oleksandr Rybalko
- Technical University of Denmark, Ørsteds Plads 349, 2800 Kgs. Lyngby, Denmark
| | - Sean Bowen
- Technical University of Denmark, Ørsteds Plads 349, 2800 Kgs. Lyngby, Denmark
| | - Vitaliy Zhurbenko
- Technical University of Denmark, Ørsteds Plads 349, 2800 Kgs. Lyngby, Denmark
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11
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Glyavin MY, Chirkov AV, Denisov GG, Fokin AP, Kholoptsev VV, Kuftin AN, Luchinin AG, Golubyatnikov GY, Malygin VI, Morozkin MV, Manuilov VN, Proyavin MD, Sedov AS, Sokolov EV, Tai EM, Tsvetkov AI, Zapevalov VE. Experimental tests of a 263 GHz gyrotron for spectroscopic applications and diagnostics of various media. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:054705. [PMID: 26026544 DOI: 10.1063/1.4921322] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A 263 GHz continuous-wave (CW) gyrotron was developed at the IAP RAS for future applications as a microwave power source in Dynamic Nuclear Polarization / Nuclear magnetic resonance (DNP/NMR) spectrometers. A new experimental facility with a computerized control was built to test this and subsequent gyrotrons. We obtained the maximum CW power up to 1 kW in the 15 kV/0.4 A operation regime. The power about 10 W, which is sufficient for many spectroscopic applications, was realized in the low current 14 kV/0.02 A regime. The possibility of frequency tuning by variation of the coolant temperature about 4 MHz/1 °C was demonstrated. The spectral width of the gyrotron radiation was about 10(-6).
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Affiliation(s)
- M Yu Glyavin
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - A V Chirkov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - G G Denisov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - A P Fokin
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - V V Kholoptsev
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - A N Kuftin
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - A G Luchinin
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - G Yu Golubyatnikov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - V I Malygin
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - M V Morozkin
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - V N Manuilov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - M D Proyavin
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - A S Sedov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | | | - E M Tai
- Gycom Ltd., Nizhny Novgorod, Russia
| | - A I Tsvetkov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - V E Zapevalov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
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12
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Can TV, Ni QZ, Griffin RG. Mechanisms of dynamic nuclear polarization in insulating solids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 253:23-35. [PMID: 25797002 PMCID: PMC4371145 DOI: 10.1016/j.jmr.2015.02.005] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 02/05/2015] [Accepted: 02/09/2015] [Indexed: 05/04/2023]
Abstract
Dynamic nuclear polarization (DNP) is a technique used to enhance signal intensities in NMR experiments by transferring the high polarization of electrons to their surrounding nuclei. The past decade has witnessed a renaissance in the development of DNP, especially at high magnetic fields, and its application in several areas including biophysics, chemistry, structural biology and materials science. Recent technical and theoretical advances have expanded our understanding of established experiments: for example, the cross effect DNP in samples spinning at the magic angle. Furthermore, new experiments suggest that our understanding of the Overhauser effect and its applicability to insulating solids needs to be re-examined. In this article, we summarize important results of the past few years and provide quantum mechanical explanations underlying these results. We also discuss future directions of DNP and current limitations, including the problem of resolution in protein spectra recorded at 80-100 K.
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Affiliation(s)
- T V Can
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Q Z Ni
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - R G Griffin
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
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13
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Su Y, Andreas L, Griffin RG. Magic angle spinning NMR of proteins: high-frequency dynamic nuclear polarization and (1)H detection. Annu Rev Biochem 2015; 84:465-97. [PMID: 25839340 DOI: 10.1146/annurev-biochem-060614-034206] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Magic angle spinning (MAS) NMR studies of amyloid and membrane proteins and large macromolecular complexes are an important new approach to structural biology. However, the applicability of these experiments, which are based on (13)C- and (15)N-detected spectra, would be enhanced if the sensitivity were improved. Here we discuss two advances that address this problem: high-frequency dynamic nuclear polarization (DNP) and (1)H-detected MAS techniques. DNP is a sensitivity enhancement technique that transfers the high polarization of exogenous unpaired electrons to nuclear spins via microwave irradiation of electron-nuclear transitions. DNP boosts NMR signal intensities by factors of 10(2) to 10(3), thereby overcoming NMR's inherent low sensitivity. Alternatively, it permits structural investigations at the nanomolar scale. In addition, (1)H detection is feasible primarily because of the development of MAS rotors that spin at frequencies of 40 to 60 kHz or higher and the preparation of extensively (2)H-labeled proteins.
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Affiliation(s)
- Yongchao Su
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139;
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14
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Lewis SM, Nanni EA, Temkin RJ. Direct Machining of Low-Loss THz Waveguide Components With an RF Choke. IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS : A PUBLICATION OF THE IEEE MICROWAVE THEORY AND TECHNIQUES SOCIETY 2014; 24:842-844. [PMID: 25821412 PMCID: PMC4374357 DOI: 10.1109/lmwc.2014.2303161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present results for the successful fabrication of low-loss THz metallic waveguide components using direct machining with a CNC end mill. The approach uses a split-block machining process with the addition of an RF choke running parallel to the waveguide. The choke greatly reduces coupling to the parasitic mode of the parallel-plate waveguide produced by the split-block. This method has demonstrated loss as low as 0.2 dB/cm at 280 GHz for a copper WR-3 waveguide. It has also been used in the fabrication of 3 and 10 dB directional couplers in brass, demonstrating excellent agreement with design simulations from 240-260 GHz. The method may be adapted to structures with features on the order of 200 μm.
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Affiliation(s)
- Samantha M Lewis
- Department of Nuclear Science and Engineering and the Plasma Science and Fusion Center (PSFC), Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Emilio A Nanni
- Department of Electrical Engineering and Computer Science and the PSFC, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Richard J Temkin
- Department of Physics and the PSFC, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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15
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Zotova IV, Ginzburg NS, Sergeev AS, Kocharovskaya ER, Zaslavsky VY. Conversion of an electromagnetic wave into a periodic train of solitons under cyclotron resonance interaction with a backward beam of unexcited electron-oscillators. PHYSICAL REVIEW LETTERS 2014; 113:143901. [PMID: 25325645 DOI: 10.1103/physrevlett.113.143901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Indexed: 06/04/2023]
Abstract
The possibility of the conversion of intense continuous microwave radiation into a periodic train of short pulses by means of resonant interaction with a beam of unexcited cyclotron electron oscillators moving backward is shown. In such a system there is a certain range of parameters where the incident stationary signal splits into a train of short pulses and each of them can be interpreted as a soliton. It is proposed to use this effect for amplitude modulation of radiation of short wavelength gyrotrons.
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Affiliation(s)
- I V Zotova
- Institute of Applied Physics RAS, GSP-120 Nizhny Novgorod, Russia
| | - N S Ginzburg
- Institute of Applied Physics RAS, GSP-120 Nizhny Novgorod, Russia and Nizhny Novgorod State University, 603950 Nizhny Novgorod, Russia
| | - A S Sergeev
- Institute of Applied Physics RAS, GSP-120 Nizhny Novgorod, Russia
| | | | - V Yu Zaslavsky
- Institute of Applied Physics RAS, GSP-120 Nizhny Novgorod, Russia and Nizhny Novgorod State University, 603950 Nizhny Novgorod, Russia
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16
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Kim SG, Kim DS, Choe MS, Lee W, So J, Choi EM. Cold testing of quasi-optical mode converters using a generator for non-rotating high-order gyrotron modes. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:104709. [PMID: 25362436 DOI: 10.1063/1.4898180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this paper, we test the performance of a quasi-optical, internal-gyrotron mode converter. When cold testing mode converters, a rotating higher-order mode is commonly used. However, this requires a nontrivial design and precise alignment. We thus propose a new technique for testing gyrotron mode converters by using a simple, non-rotating, higher-order mode generator. We demonstrate the feasibility of this technique for a W-band gyrotron quasi-optical mode converter by examining the excitation of a TE6,2 mode from a non-rotating mode generator. Our results demonstrate that this new cold-test scheme is an easy and efficient method for verifying the performance of quasi-optical mode converters.
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Affiliation(s)
- S G Kim
- School of Electrical and Computer Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, South Korea
| | - D S Kim
- Physics Department, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, South Korea
| | - M S Choe
- Physics Department, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, South Korea
| | - W Lee
- Agency for Defense Development (ADD), Daejeon 305-152, South Korea
| | - J So
- Agency for Defense Development (ADD), Daejeon 305-152, South Korea
| | - E M Choi
- School of Electrical and Computer Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, South Korea
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17
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Takahashi H, Fernández-de-Alba C, Lee D, Maurel V, Gambarelli S, Bardet M, Hediger S, Barra AL, De Paëpe G. Optimization of an absolute sensitivity in a glassy matrix during DNP-enhanced multidimensional solid-state NMR experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 239:91-99. [PMID: 24480716 DOI: 10.1016/j.jmr.2013.12.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 12/03/2013] [Accepted: 12/09/2013] [Indexed: 06/03/2023]
Abstract
Thanks to instrumental and theoretical development, notably the access to high-power and high-frequency microwave sources, high-field dynamic nuclear polarization (DNP) on solid-state NMR currently appears as a promising solution to enhance nuclear magnetization in many different types of systems. In magic-angle-spinning DNP experiments, systems of interest are usually dissolved or suspended in glass-forming matrices doped with polarizing agents and measured at low temperature (down to ∼100K). In this work, we discuss the influence of sample conditions (radical concentration, sample temperature, etc.) on DNP enhancements and various nuclear relaxation times which affect the absolute sensitivity of DNP spectra, especially in multidimensional experiments. Furthermore, DNP-enhanced solid-state NMR experiments performed at 9.4 T are complemented by high-field CW EPR measurements performed at the same magnetic field. Microwave absorption by the DNP glassy matrix is observed even below the glass transition temperature caused by softening of the glass. Shortening of electron relaxation times due to glass softening and its impact in terms of DNP sensitivity is discussed.
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Affiliation(s)
- Hiroki Takahashi
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble, France
| | - Carlos Fernández-de-Alba
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble, France
| | - Daniel Lee
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble, France
| | - Vincent Maurel
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble, France
| | - Serge Gambarelli
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble, France
| | - Michel Bardet
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble, France
| | - Sabine Hediger
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble, France
| | - Anne-Laure Barra
- Laboratoire National des Champs Magnétiques Intenses, CNRS, F-38042 Grenoble, France
| | - Gaël De Paëpe
- Laboratoire de Chimie Inorganique et Biologique, UMR-E3 (CEA/UJF) and CNRS, Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble, France.
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18
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Nanni EA, Lewis SM, Shapiro MA, Griffin RG, Temkin RJ. Photonic-band-gap traveling-wave gyrotron amplifier. PHYSICAL REVIEW LETTERS 2013; 111:235101. [PMID: 24476286 PMCID: PMC4066963 DOI: 10.1103/physrevlett.111.235101] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Indexed: 05/18/2023]
Abstract
We report the experimental demonstration of a gyrotron traveling-wave-tube amplifier at 250 GHz that uses a photonic band gap (PBG) interaction circuit. The gyrotron amplifier achieved a peak small signal gain of 38 dB and 45 W output power at 247.7 GHz with an instantaneous -3 dB bandwidth of 0.4 GHz. The amplifier can be tuned for operation from 245-256 GHz. The widest instantaneous -3 dB bandwidth of 4.5 GHz centered at 253.25 GHz was observed with a gain of 24 dB. The PBG circuit provides stability from oscillations by supporting the propagation of transverse electric (TE) modes in a narrow range of frequencies, allowing for the confinement of the operating TE03-like mode while rejecting the excitation of oscillations at nearby frequencies. This experiment achieved the highest frequency of operation for a gyrotron amplifier; at present, there are no other amplifiers in this frequency range that are capable of producing either high gain or high output power. This result represents the highest gain observed above 94 GHz and the highest output power achieved above 140 GHz by any conventional-voltage vacuum electron device based amplifier.
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Affiliation(s)
- E A Nanni
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - S M Lewis
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - M A Shapiro
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - R G Griffin
- Department of Chemistry and the Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - R J Temkin
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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19
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Jawla S, Ni QZ, Barnes A, Guss W, Daviso E, Herzfeld J, Griffin R, Temkin R. Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy. JOURNAL OF INFRARED, MILLIMETER AND TERAHERTZ WAVES 2013; 34:42-52. [PMID: 23539422 PMCID: PMC3607393 DOI: 10.1007/s10762-012-9947-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a 13C-Urea sample using this gyrotron.
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Affiliation(s)
- Sudheer Jawla
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - Qing Zhe Ni
- Francis Bitter Magnet Lab and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - Alexander Barnes
- Francis Bitter Magnet Lab and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - William Guss
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - Eugenio Daviso
- Francis Bitter Magnet Lab and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
- Department of Chemistry, Brandies University, Waltham, MA-02454, USA
| | - Judith Herzfeld
- Department of Chemistry, Brandies University, Waltham, MA-02454, USA
| | - Robert Griffin
- Francis Bitter Magnet Lab and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
| | - Richard Temkin
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
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20
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Matsuki Y, Ueda K, Idehara T, Ikeda R, Ogawa I, Nakamura S, Toda M, Anai T, Fujiwara T. Helium-cooling and -spinning dynamic nuclear polarization for sensitivity-enhanced solid-state NMR at 14 T and 30 K. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 225:1-9. [PMID: 23079589 DOI: 10.1016/j.jmr.2012.09.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 09/12/2012] [Accepted: 09/18/2012] [Indexed: 06/01/2023]
Abstract
We describe a (1)H polarization enhancement via dynamic nuclear polarization (DNP) at very low sample temperature T≈30 K under magic-angle spinning (MAS) conditions for sensitivity-enhanced solid-state NMR measurement. Experiments were conducted at a high external field strength of 14.1 T. For MAS DNP experiments at T<<90 K, a new probe system using cold helium gas for both sample-cooling and -spinning was developed. The novel system can sustain a low sample temperature between 30 and 90K for a period of time >10 h under MAS at ν(R)≈3 kHz with liquid He consumption of ≈6 L/h. As a microwave source, we employed a high-power, continuously frequency-tunable gyrotron. At T≈34 K, (1)H DNP enhancement factors of 47 and 23 were observed with and without MAS, respectively. On the basis of these observations, a discussion on the total NMR sensitivity that takes into account the effect of sample temperature and external field strength used in DNP experiments is presented. It was determined that the use of low sample temperature and high external field is generally rewarding for the total sensitivity, in spite of the slower polarization buildup at lower temperature and lower DNP efficiency at higher field. These findings highlight the potential of the current continuous-wave DNP technique also at very high field conditions suitable to analyze large and complex systems, such as biological macromolecules.
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Affiliation(s)
- Yoh Matsuki
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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21
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Barnes AB, Markhasin E, Daviso E, Michaelis VK, Nanni EA, Jawla SK, Mena EL, DeRocher R, Thakkar A, Woskov PP, Herzfeld J, Temkin RJ, Griffin RG. Dynamic nuclear polarization at 700 MHz/460 GHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 224:1-7. [PMID: 23000974 PMCID: PMC3965575 DOI: 10.1016/j.jmr.2012.08.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 07/29/2012] [Accepted: 08/03/2012] [Indexed: 05/05/2023]
Abstract
We describe the design and implementation of the instrumentation required to perform DNP-NMR at higher field strengths than previously demonstrated, and report the first magic-angle spinning (MAS) DNP-NMR experiments performed at (1)H/e(-) frequencies of 700 MHz/460 GHz. The extension of DNP-NMR to 16.4 T has required the development of probe technology, cryogenics, gyrotrons, and microwave transmission lines. The probe contains a 460 GHz microwave channel, with corrugated waveguide, tapers, and miter-bends that couple microwave power to the sample. Experimental efficiency is increased by a cryogenic exchange system for 3.2 mm rotors within the 89 mm bore. Sample temperatures ≤85 K, resulting in improved DNP enhancements, are achieved by a novel heat exchanger design, stainless steel and brass vacuum jacketed transfer lines, and a bronze probe dewar. In addition, the heat exchanger is preceded with a nitrogen drying and generation system in series with a pre-cooling refrigerator. This reduces liquid nitrogen usage from >700 l per day to <200 l per day and allows for continuous (>7 days) cryogenic spinning without detrimental frost or ice formation. Initial enhancements, ε=-40, and a strong microwave power dependence suggests the possibility for considerable improvement. Finally, two-dimensional spectra of a model system demonstrate that the higher field provides excellent resolution, even in a glassy, cryoprotecting matrix.
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Affiliation(s)
- Alexander B Barnes
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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22
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Matsuoka S. [Structural study on small molecules in biological solid samples by using solid state NMR]. YAKUGAKU ZASSHI 2012; 132:969-78. [PMID: 23023412 DOI: 10.1248/yakushi.132.969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Many small molecule drugs have molecular targets that are non-crystalline and insoluble biological matrices, such as proteins embedded in lipid membrane, cell membranes, and cell walls. To understand the action mechanisms, it is essential to determine the binding structure with atomic-level resolution. Although solution nuclear magnetic resonance (NMR) and X-ray crystallography have been used to determine molecular structures of cell membrane and membrane proteins, these methods are unable to reproduce the complexity of biological systems because either solubilization or crystallization of target molecules is requisite. For structural studies of insoluble non-crystalline biological samples, so-called "biological solids", high resolution distance measurements using solid-state NMR are indispensable techniques, of which rotational-echo double-resonance (REDOR) is one of the most widely used methods. In this paper, a brief introduction to REDOR NMR and its applications to structural studies on the antifungal amphotericin B-membrane phospholipid complex and a structural elucidation of photorespiration metabolites in plant cells without extraction or isolation is provided.
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Affiliation(s)
- Shigeru Matsuoka
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
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23
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Barnes AB, Nanni EA, Herzfeld J, Griffin RG, Temkin RJ. A 250 GHz gyrotron with a 3 GHz tuning bandwidth for dynamic nuclear polarization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 221:147-53. [PMID: 22743211 PMCID: PMC3405196 DOI: 10.1016/j.jmr.2012.03.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 03/07/2012] [Accepted: 03/17/2012] [Indexed: 05/05/2023]
Abstract
We describe the design and implementation of a novel tunable 250 GHz gyrotron oscillator with >10 W output power over most of a 3 GHz band and >35 W peak power. The tuning bandwidth and power are sufficient to generate a >1 MHz nutation frequency across the entire nitroxide EPR lineshape for cross effect DNP, as well as to excite solid effect transitions utilizing other radicals, without the need for sweeping the NMR magnetic field. Substantially improved tunability is achieved by implementing a long (23 mm) interaction cavity that can excite higher order axial modes by changing either the magnetic field of the gyrotron or the cathode potential. This interaction cavity excites the rotating TE(₅,₂,q) mode, and an internal mode converter outputs a high-quality microwave beam with >94% Gaussian content. The gyrotron was integrated into a DNP spectrometer, resulting in a measured DNP enhancement of 54 on the membrane protein bacteriorhodopsin.
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Affiliation(s)
- Alexander B Barnes
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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24
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Nanni EA, Jawla SK, Shapiro MA, Woskov PP, Temkin RJ. Low-Loss Transmission Lines for High-Power Terahertz Radiation. JOURNAL OF INFRARED, MILLIMETER AND TERAHERTZ WAVES 2012; 33:695-714. [PMID: 23162673 PMCID: PMC3498493 DOI: 10.1007/s10762-012-9870-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Applications of high-power Terahertz (THz) sources require low-loss transmission lines to minimize loss, prevent overheating and preserve the purity of the transmission mode. Concepts for THz transmission lines are reviewed with special emphasis on overmoded, metallic, corrugated transmission lines. Using the fundamental HE(11) mode, these transmission lines have been successfully implemented with very low-loss at high average power levels on plasma heating experiments and THz dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) experiments. Loss in these lines occurs directly, due to ohmic loss in the fundamental mode, and indirectly, due to mode conversion into high order modes whose ohmic loss increases as the square of the mode index. An analytic expression is derived for ohmic loss in the modes of a corrugated, metallic waveguide, including loss on both the waveguide inner surfaces and grooves. Simulations of loss with the numerical code HFSS are in good agreement with the analytic expression. Experimental tests were conducted to determine the loss of the HE(11) mode in a 19 mm diameter, helically-tapped, three meter long brass waveguide with a design frequency of 330 GHz. The measured loss at 250 GHz was 0.029 ± 0.009 dB/m using a vector network analyzer approach and 0.047 ± 0.01 dB/m using a radiometer. The experimental results are in reasonable agreement with theory. These values of loss, amounting to about 1% or less per meter, are acceptable for the DNP NMR application. Loss in a practical transmission line may be much higher than the loss calculated for the HE(11) mode due to mode conversion to higher order modes caused by waveguide imperfections or miter bends.
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Affiliation(s)
- Emilio A. Nanni
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, USA 02139
| | - Sudheer K. Jawla
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, USA 02139
| | - Michael A. Shapiro
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, USA 02139
| | - Paul P. Woskov
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, USA 02139
| | - Richard J. Temkin
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, USA 02139
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25
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Jawla SK, Nanni EA, Shapiro MA, Woskov PP, Temkin RJ. Mode Content Determination of Terahertz Corrugated Waveguides Using Experimentally Measured Radiated Field Patterns. IEEE TRANSACTIONS ON PLASMA SCIENCE. IEEE NUCLEAR AND PLASMA SCIENCES SOCIETY 2012; 40:1530-1537. [PMID: 25264391 PMCID: PMC4175724 DOI: 10.1109/tps.2012.2190105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This work focuses on the accuracy of the mode content measurements in an overmoded corrugated waveguide using measured radiated field patterns. Experimental results were obtained at 250 GHz using a vector network analyzer with over 70 dB of dynamic range. The intensity and phase profiles of the fields radiated from the end of the 19 mm diameter helically tapped brass waveguide were measured on planes at 7, 10, and 13 cm from the waveguide end. The measured fields were back propagated to the waveguide aperture to provide three independent estimates of the field at the waveguide exit aperture. Projecting that field onto the modes of the guide determined the waveguide mode content. The three independent mode content estimates were found to agree with one another to an accuracy of better than ±0.3%. These direct determinations of the mode content were compared with indirect measurements using the experimentally measured amplitude in three planes, with the phase determined by a phase retrieval algorithm. The phase retrieval technique using the planes at 7, 10, and 13 cm yielded a mode content estimate in excellent agreement, within 0.3%, of the direct measurements. Phase retrieval results using planes at 10, 20, and 30 cm were less accurate due to truncation of the measurement in the transverse plane. The reported measurements benefited greatly from a precise mechanical alignment of the scanner with respect to the waveguide axis. These results will help to understand the accuracy of mode content measurements made directly in cold test and indirectly in hot test using the phase retrieval technique.
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Affiliation(s)
- Sudheer K. Jawla
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Emilio A. Nanni
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Michael A. Shapiro
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Paul P. Woskov
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Richard J. Temkin
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
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