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Tomar N, Roy I, Shri S, Chinthala BD, Shekhar M, Srivastava A, Ranhotra PS, Singh CP, Bhattacharyya A. Modern pollen dispersal in relation to present vegetation distribution and land use in the Baspa valley, Kinnaur, western Himalayas. Environ Monit Assess 2024; 196:194. [PMID: 38265534 DOI: 10.1007/s10661-024-12340-8] [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: 09/11/2023] [Accepted: 01/08/2024] [Indexed: 01/25/2024]
Abstract
Interpretation of a fossil pollen data for the vegetation and climate reconstruction of any region needs a modern pollen-vegetation analogue for its calibration. We analyzed the surface sediments and moss polsters for the pollen and microcharcoal records to understand the modern pollen-vegetation relationship and human activities in the Baspa Valley, Kinnaur, Himachal Pradesh. Presently, valley is occupied by the arboreal and non-arboreal vegetation of temperate to subalpine habitats and land use activities. The recovered pollen assemblages showed variability in the dispersal behavior of pollen of taxa growing along the valley transect and also captured the signals of human activities over land use. The overall dominance of arboreal pollen in the recovered pollen assemblage corresponds with the dominant growth of conifers and broadleaf tree taxa and represents the valley vegetation at a regional scale. However, the profuse pollen production of a few arboreal taxa and long distance pollen transport from one vegetation zone to other by the strong upthermic valley winds could bias the pollen representation of in-situ vegetation. The high pollen frequency of non-arboreal taxa in the open meadows represents the near vicinity to their plant source. Human activities like fire burning and cultivation by the local population are evident by the recovery of microcharcoal particles and pollen of plants belonging to Cerealia Poaceae, Asteraceae, Amaranthaceae, Polygonaceae, Rosaceae, Juglandaceae, etc. The dataset taken as modern pollen-vegetation analogue is useful to assess past changes in the vegetation and land cover in relation to climate and human factors for future sustenance.
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Affiliation(s)
- Nidhi Tomar
- Birbal Sahni Institute of Palaeosciences, 53 University Road, Lucknow, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Ipsita Roy
- Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune, India
| | - Shreya Shri
- Rajat P.G. College, University of Lucknow, Lucknow, India
| | | | - Mayank Shekhar
- Birbal Sahni Institute of Palaeosciences, 53 University Road, Lucknow, India
| | - Amber Srivastava
- Botanical Survey of India, Northern Regional Centre, Dehradun, India
| | - Parminder Singh Ranhotra
- Birbal Sahni Institute of Palaeosciences, 53 University Road, Lucknow, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
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Bhattacharyya A, Dhyani R, Joshi R, Shekhar M, Kuniyal JC, Ranhotra PS, Singh SP. Is survival of Himalayan Cedar (Cedrus deodara) threatened? An evaluation based on predicted scenarios of its growth trend under future climate change. Sci Total Environ 2023; 882:163630. [PMID: 37086989 DOI: 10.1016/j.scitotenv.2023.163630] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 04/17/2023] [Accepted: 04/17/2023] [Indexed: 05/03/2023]
Abstract
Global warming is likely to become one of the significant drivers of forest losses in the Hindu-Kush Himalaya (HKH) during the 21st century. Better understanding of how forest ecosystem will respond to global warming requires a precise knowledge of site and species specific responses to climate change. We applied dendrochronological technique to quantify and predict future growth trend of Himalayan cedar (Cedrus deodara), a tree of high commercial importance, and explored its spatial growth variability under two different climatic regimes from 17 deodar sites in the HKH. Of the two climate regimes, one is dominated by the monsoon rainfall and the other by the westerly disturbances. Analysis of tree ring width and climate (monthly temperature and precipitation) data reveals that the spring (March-May) temperature and precipitation affect the growth of deodar negatively and positively, respectively. We used Generalized Least Squares (GLS) regression model to forecast future growth of deodar by taking an ensemble of 40 General Circulation Models (GCMs) for emission scenarios RCP 4.5 and RCP 8.5. Predicted growth trends indicate the decline between 34 % and 38 % under RCP 4.5, and between 29 % and 32 % under RCP 8.5 scenarios, for the low and mid latitude sites. In contrast, a moderate increase in growth was observed in high latitude sites under the both climate scenarios. The study shows more drought stress to deodar trees growing in monsoon areas in mid-and low-latitude sites where less snow melt and low precipitation during the spring season are predicted to increase evapotranspiration. In comparison, in the higher latitude sites where there is a high snowfall due to western disturbances, the growth of deodar is predicted to increase. These findings may be used to take suitable migratory steps for the conservation of deodar in the HKH region.
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Affiliation(s)
- Amalava Bhattacharyya
- Birbal Sahni Institute of Palaeosciences, 53 University Road, Lucknow 226 007, India.
| | - Rupesh Dhyani
- G. B. Pant National Institute of Himalayan Environment, Kosi-Katarmal, Almora 263 643, Uttarakhand, India
| | - Rajesh Joshi
- G. B. Pant National Institute of Himalayan Environment, Sikkim Regional Centre, Pangthang 737 103, Sikkim, India.
| | - Mayank Shekhar
- Birbal Sahni Institute of Palaeosciences, 53 University Road, Lucknow 226 007, India
| | - Jagdish Chandra Kuniyal
- G. B. Pant National Institute of Himalayan Environment, Kosi-Katarmal, Almora 263 643, Uttarakhand, India.
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Shekhar M, Lee WS, Akatay MC, Maciel L, Tang W, Miller JT, Stach EA, Neurock M, Delgass WN, Ribeiro FH. Water-gas shift reaction over supported Au nanoparticles. J Catal 2022. [DOI: 10.1016/j.jcat.2021.12.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Singh SP, Bhattacharyya A, Mittal A, Pandey A, Tewari A, Latwal A, David B, Adhikari BS, Kumar D, Negi GCS, Mir IA, Tamta KK, Sambhav K, Shekhar M, Phulara M, Manzoor M, Singh N, Tewari P, Ranhotra PS, Singh P, Dhaila P, Sah P, Kumar R, Joshi R, Rawal RS, Rawal R, Singh RD, Shah S, Sharma S, Nanda SA, Gumber S, Singh U, Reshi Z. Indian Himalayan Timberline Ecotone in Response to Climate Change – Initial Findings. CURR SCI INDIA 2021. [DOI: 10.18520/cs/v120/i5/859-871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Ali SN, Dubey J, Ghosh R, Quamar MF, Sharma A, Morthekai P, Dimri AP, Shekhar M, Arif M, Agrawal S. High frequency abrupt shifts in the Indian summer monsoon since Younger Dryas in the Himalaya. Sci Rep 2018; 8:9287. [PMID: 29915324 PMCID: PMC6006316 DOI: 10.1038/s41598-018-27597-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [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: 01/24/2018] [Accepted: 06/01/2018] [Indexed: 11/15/2022] Open
Abstract
In order to quantify the Indian summer monsoon (ISM) variability for a monsoon dominated agrarian based Indian socio-economy, we used combined high resolution δ13C, total organic carbon (TOC), sediment texture and environmental magnetic data of the samples from a ~3 m deep glacial outwash sedimentary profile from the Sikkim Himalaya. Our decadal to centennial scale records identified five positive and three negative excursions of the ISM since last ~13 ka. The most prominent abrupt negative ISM shift was observed during the termination of the Younger Dryas (YD) between ~11.7 and 11.4 ka. While, ISM was stable between ~11 and 6 ka, and declined prominently between 6 and 3 ka. Surprisingly, during both the Medieval Warm Period (MWP) and Little Ice age (LIA) spans, ISM was strong in this part of the Himalaya. These regional changes in ISM were coupled to southward shifting in mean position of the Intertropical Convergence Zone (ITCZ) and variations in East Asian monsoon (EAM). Our rainfall reconstructions are broadly in agreement with local, regional reconstructions and PMIP3, CSIRO-MK3L model simulations.
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Affiliation(s)
| | - Jyotsna Dubey
- Birbal Sahni Institute of Palaeosciences, Lucknow, India
| | - Ruby Ghosh
- Birbal Sahni Institute of Palaeosciences, Lucknow, India
| | | | - Anupam Sharma
- Birbal Sahni Institute of Palaeosciences, Lucknow, India
| | - P Morthekai
- Birbal Sahni Institute of Palaeosciences, Lucknow, India
| | - A P Dimri
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Mayank Shekhar
- Birbal Sahni Institute of Palaeosciences, Lucknow, India
| | - Md Arif
- Birbal Sahni Institute of Palaeosciences, Lucknow, India
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Bhattacharyya A, Stoffel M, Shekhar M, Ballesteros Canovas JA, Trappmann D. Dendrogeomorphic Potential of the Himalaya – Case Studies of Process Dating of Natural Hazards in Kullu Valley, Himachal Pradesh. CURR SCI INDIA 2017. [DOI: 10.18520/cs/v113/i12/2317-2324] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Shekhar M, Shriwastav A, Bose P, Hameed S. Microfiltration of algae: Impact of algal species, backwashing mode and duration of filtration cycle. ALGAL RES 2017. [DOI: 10.1016/j.algal.2017.01.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Shekhar M, Singh N, Kumar S, Kiran R. Role of mould occurrence in aflatoxin build-up and variability of Aspergillus flavusisolates from maize grains across India. Quality Assurance and Safety of Crops & Foods 2017. [DOI: 10.3920/qas2015.0720] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- M. Shekhar
- ICAR-Indian Institute of Maize Research, Pusa Campus, IARI, 110012 New Delhi, India
| | - N. Singh
- ICAR-Indian Institute of Maize Research, Pusa Campus, IARI, 110012 New Delhi, India
| | - S. Kumar
- Directorate of Maize Research, Pusa Campus, IARI, 110012 New Delhi, India
| | - R. Kiran
- ICAR-Indian Institute of Maize Research, Pusa Campus, IARI, 110012 New Delhi, India
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Vermaas JV, Trebesch N, Mayne CG, Thangapandian S, Shekhar M, Mahinthichaichan P, Baylon JL, Jiang T, Wang Y, Muller MP, Shinn E, Zhao Z, Wen PC, Tajkhorshid E. Microscopic Characterization of Membrane Transporter Function by In Silico Modeling and Simulation. Methods Enzymol 2016; 578:373-428. [PMID: 27497175 PMCID: PMC6404235 DOI: 10.1016/bs.mie.2016.05.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [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: 12/05/2022]
Abstract
Membrane transporters mediate one of the most fundamental processes in biology. They are the main gatekeepers controlling active traffic of materials in a highly selective and regulated manner between different cellular compartments demarcated by biological membranes. At the heart of the mechanism of membrane transporters lie protein conformational changes of diverse forms and magnitudes, which closely mediate critical aspects of the transport process, most importantly the coordinated motions of remotely located gating elements and their tight coupling to chemical processes such as binding, unbinding and translocation of transported substrate and cotransported ions, ATP binding and hydrolysis, and other molecular events fueling uphill transport of the cargo. An increasing number of functional studies have established the active participation of lipids and other components of biological membranes in the function of transporters and other membrane proteins, often acting as major signaling and regulating elements. Understanding the mechanistic details of these molecular processes require methods that offer high spatial and temporal resolutions. Computational modeling and simulations technologies empowered by advanced sampling and free energy calculations have reached a sufficiently mature state to become an indispensable component of mechanistic studies of membrane transporters in their natural environment of the membrane. In this article, we provide an overview of a number of major computational protocols and techniques commonly used in membrane transporter modeling and simulation studies. The article also includes practical hints on effective use of these methods, critical perspectives on their strengths and weak points, and examples of their successful applications to membrane transporters, selected from the research performed in our own laboratory.
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Affiliation(s)
- J V Vermaas
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - N Trebesch
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - C G Mayne
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - S Thangapandian
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - M Shekhar
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - P Mahinthichaichan
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - J L Baylon
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - T Jiang
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Y Wang
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - M P Muller
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - E Shinn
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Z Zhao
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - P-C Wen
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - E Tajkhorshid
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
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Haynes B, Zhang Y, Li J, Petit S, Westwell A, Mao G, Shekhar M. Abstract P3-14-06: Evaluation of the therapeutic efficacy of a Rad6 small molecule inhibitor in triple negative breast cancer cells. Cancer Res 2016. [DOI: 10.1158/1538-7445.sabcs15-p3-14-06] [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: 11/16/2022]
Abstract
Abstract
Triple negative breast cancers (TNBCs) lack estrogen and progesterone receptors and Her2/neu amplification, and are hence not treatable with therapies targeting these molecules. TNBCs have upregulated DNA damage response mechanisms, including the Rad6 postreplication repair (PRR) pathway, that potentially contribute to chemoresistance. Rad6 is a major component of the PRR pathway and its ubiquitin conjugating (UBC) activity is critical for its function. Rad6 expression is low in normal breast cells and tissues but the Rad6 homolog Rad6B is overexpressed in invasive, metastatic and chemoresistant BrCas. Constitutive overexpression of Rad6B in MCF10A cells induces resistance to cisplatin and doxorubicin. TCGA analysis of TNBC patient data showed an association between high Rad6B expression (but not Rad6A) and decreased overall survival. We recently reported the development of a novel Rad6-selective small molecule inhibitor (SMI#9) that inhibits Rad6 UBC activity, migration, and induces apoptosis in TNBC cells but has no effect on MCF10A cells. Since SMI#9 has limited aqueous solubility, in this study we synthesized a modified analog of SMI#9 to enable conjugation via a hydrolyzable ester bond to gold nanoparticle (GNP) and to improve delivery. GNP tethered SMI#9 (SMI#9-GNP) was characterized for purity, ligand conjugation and size by thermogravimetric analysis, atomic force microscopy, transmission electron microscopy, UV-Vis spectroscopy and zeta sizer, and for cellular uptake and drug release by FTIR and mass spectrometry. We compared the activities of SMI#9-GNP and free SMI#9 for cytotoxicity and intracellular localization in mesenchymal (MDA-MB-231 and SUM1315) and basal (MDA-MB-468 and HCC1937) subtypes of TNBC, and in MCF10A cells. Whereas free SMI#9 was cytotoxic to all TNBC cells, SMI#9-GNP demonstrated as good or better cytotoxicity than free SMI#9 only in mesenchymal TNBC cells. MCF10A cells were unaffected by both free and SMI#9-GNP. Consistent with cellular sensitivities, SMI#9-GNP is efficiently endocytosed and processed in lysosomes in mesenchymal TNBC cells, while uptake into basal TNBC cells is compromised by cell microenvironment induced SMI#9-GNP aggregation. SMI#9-GNP treatment induces mitochondrial dysfunction, and stabilization and hyperactivation of PARP-1 that was commensurate with autophagy (indicated by LC3-I to LC3-II conversion). Rad6 loss and PARP-1 hyperactivation are associated with mitochondrial dysfunction, and since inhibition of Rad6 induces both mitochondrial dysfunction and PARP-1 activation this implicates a potential novel role for Rad6 in linking these processes. In summary, our data show that SMI#9-GNP is a suitable delivery vehicle and that the SMI#9 released from GNP conjugate functions similarly as free SMI#9. Our data also illustrate how cell microenvironment induced changes in the physical properties of GNP-drug conjugates can have important implications in the application of nanoparticles in cancer therapy. Supported by NIH R21 CA178117.
Citation Format: Haynes B, Zhang Y, Li J, Petit S, Westwell A, Mao G, Shekhar M. Evaluation of the therapeutic efficacy of a Rad6 small molecule inhibitor in triple negative breast cancer cells. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-14-06.
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Affiliation(s)
- B Haynes
- Wayne State University, Detroit, MI; Cardiff University, Cardiff, Wales, United Kingdom
| | - Y Zhang
- Wayne State University, Detroit, MI; Cardiff University, Cardiff, Wales, United Kingdom
| | - J Li
- Wayne State University, Detroit, MI; Cardiff University, Cardiff, Wales, United Kingdom
| | - S Petit
- Wayne State University, Detroit, MI; Cardiff University, Cardiff, Wales, United Kingdom
| | - A Westwell
- Wayne State University, Detroit, MI; Cardiff University, Cardiff, Wales, United Kingdom
| | - G Mao
- Wayne State University, Detroit, MI; Cardiff University, Cardiff, Wales, United Kingdom
| | - M Shekhar
- Wayne State University, Detroit, MI; Cardiff University, Cardiff, Wales, United Kingdom
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Sabnis KD, Cui Y, Akatay MC, Shekhar M, Lee WS, Miller JT, Delgass WN, Ribeiro FH. Water–gas shift catalysis over transition metals supported on molybdenum carbide. J Catal 2015. [DOI: 10.1016/j.jcat.2015.08.017] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Xie H, Lu J, Shekhar M, Elam JW, Delgass WN, Ribeiro FH, Weitz E, Poeppelmeier KR. Synthesis of Na-Stabilized Nonporous t-ZrO2 Supports and Pt/t-ZrO2 Catalysts and Application to Water-Gas-Shift Reaction. ACS Catal 2012. [DOI: 10.1021/cs300596q] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hong Xie
- Center for Catalysis and Surface
Science, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Junling Lu
- Energy Systems Division, Argonne National Laboratory, 9700 South Cass Avenue,
Argonne, Illinois 60439, United States
| | - Mayank Shekhar
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette,
Indiana 47907, United States
| | - Jeffery W. Elam
- Energy Systems Division, Argonne National Laboratory, 9700 South Cass Avenue,
Argonne, Illinois 60439, United States
| | - W. Nicholas Delgass
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette,
Indiana 47907, United States
| | - Fabio H. Ribeiro
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette,
Indiana 47907, United States
| | - Eric Weitz
- Center for Catalysis and Surface
Science, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Kenneth R. Poeppelmeier
- Center for Catalysis and Surface
Science, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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Shekhar M, Wang J, Lee WS, Williams WD, Kim SM, Stach EA, Miller JT, Delgass WN, Ribeiro FH. Size and support effects for the water-gas shift catalysis over gold nanoparticles supported on model Al2O3 and TiO2. J Am Chem Soc 2012; 134:4700-8. [PMID: 22316316 DOI: 10.1021/ja210083d] [Citation(s) in RCA: 251] [Impact Index Per Article: 20.9] [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
The water-gas shift (WGS) reaction rate per total mole of Au under 7% CO, 8.5% CO(2), 22% H(2)O, and 37% H(2) at 1 atm for Au/Al(2)O(3) catalysts at 180 °C and Au/TiO(2) catalysts at 120 °C varies with the number average Au particle size (d) as d(-2.2±0.2) and d(-2.7±0.1), respectively. The use of nonporous and crystalline, model Al(2)O(3) and TiO(2) supports allowed the imaging of the active catalyst and enabled a precise determination of the Au particle size distribution and particle shape using transmission electron microscopy (TEM). Further, the apparent reaction orders and the stretching frequency of CO adsorbed on Au(0) (near 2100 cm(-1)) determined by diffuse reflectance infrared spectroscopy (DRIFTS) depend on d. Because of the changes in reaction rates, kinetics, and the CO stretching frequency with number average Au particle size, it is determined that the dominant active sites are the low coordinated corner Au sites, which are 3 and 7 times more active than the perimeter Au sites for Au/Al(2)O(3) and Au/TiO(2) catalysts, respectively, and 10 times more active for Au on TiO(2) versus Al(2)O(3). From operando Fourier transform infrared spectroscopy (FTIR) experiments, it is determined that the active Au sites are metallic in nature. In addition, Au/Al(2)O(3) catalysts have a higher apparent H(2)O order (0.63) and lower apparent activation energy (9 kJ mol(-1)) than Au/TiO(2) catalysts with apparent H(2)O order of -0.42 to -0.21 and activation energy of 45-60 kJ mol(-1) at near 120 °C. From these data, we conclude that the support directly participates by activating H(2)O molecules.
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Affiliation(s)
- Mayank Shekhar
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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Williams WD, Shekhar M, Lee WS, Kispersky V, Delgass WN, Ribeiro FH, Kim SM, Stach EA, Miller JT, Allard LF. Metallic Corner Atoms in Gold Clusters Supported on Rutile Are the Dominant Active Site during Water−Gas Shift Catalysis. J Am Chem Soc 2010; 132:14018-20. [PMID: 20853899 DOI: 10.1021/ja1064262] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- W. Damion Williams
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Mayank Shekhar
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Wen-Sheng Lee
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Vincent Kispersky
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - W. Nicholas Delgass
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Fabio H. Ribeiro
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Seung Min Kim
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Eric A. Stach
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Jeffrey T. Miller
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Lawrence F. Allard
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, Birck Nanotechnology Center, West Lafayette, Indiana 47907, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
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