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Visualization of atomic scale reaction dynamics of supported nanocatalysts during oxidation and ammonia synthesis using in-situ environmental(scanning) transmission electron microscopy

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Journal of Energy Chemistry 2021年第6期30卷 281-290,I0007页

作者： Michael R.Ward robert W.Mitchell Edward D.Boyes Pratibha l.Gai The York Nanocentre University of YorkYork YO105DDUK Department of Physics University of YorkYork YO105DDUK Department of Electronic Engineering University of YorkYork YO105DDUK Department of Chemistry University of YorkYork YO105DDUK

Reaction dynamics in gases at operating temperatures at the atomic level are the basis of heterogeneous gas-solid catalyst reactions and are crucial to the catalyst *** noble metal nanocatalysts such as platinum are of interest in fuel cells and as diesel oxidation catalysts for pollution control,and practical ruthenium nanocatalysts are explored for ammonia *** and graphitic carbons are of interest as supports for the *** considerable literature on the catalytic processes on graphite and graphitic supports,reaction dynamics of the nanocatalysts on the supports in different reactive gas environments and operating temperatures at the single atom level are not well *** we present real time in-situ observations and analyses of reaction dynamics of Pt in oxidation,and practical Ru nanocatalysts in ammonia synthesis,on graphite and related supports under controlled reaction environments using a novel in-situ environmental(scanning) transmission electron microscope with single atom *** recording snapshots of the reaction dynamics,the behaviour of the catalysts is *** images reveal single metal atoms,clusters of a few atoms on the graphitic supports and the support *** all play key roles in the mobility,sintering and growth of the *** experimental findings provide new structural insights into atomic scale reaction dynamics,morphology and stability of the nanocatalysts.

关键词： In-situ visualization Atomic scale reaction dynamics In-situ environmental scanning transmission electron microscopy with single atom resolution Supported nanoparticles Ammonia synthesis Oxidation reactions

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Polyaniline Nanofiber Composites with Amines:Novel Materials for Phosgene Detection

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Nano Research 2009年第2期2卷 135-142页

作者： Shabnam Virji robert Kojima Jesse D.Fowler Joey G.Villanueva richard B.Kaner Bruce H.Weiller Materials Processing and Evaluation Department Space Materials LaboratoryThe Aerospace CorporationP.O.Box 92957/M2-248Los AngelesCA 90009USA Department of Chemistry&Biochemistry and California NanoSystems Institute University of CaliforniaLos AngelesLos AngelesCA 90095-1569USA

Several orders of magnitude of change in resistance are observed upon chemical doping and dedoping of the conducting polymer *** large conductivity range can be utilized to make sensitive chemical ***,in its nanofiber form,has even greater sensing capabilities due to the small fiber diameters,high surface area,and porous nanofiber network that enhances gas diffusion into the *** nanofibers have been synthesized using a rapid mixing method and dispersed in water allowing them to be easily modified with water soluble agents,making new composite *** nanofiber composite materials can be used to enhance detection of analytes that unmodified polyaniline would not otherwise be able to *** detection mechanism involves the reaction of an additive with the analyte to generate a strong acid that is easily detected by polyaniline,resulting in orders of magnitude changes in *** reaction of the additive alone with the analyte produces no electrical response,*** this paper,an array of amine-polyaniline nanofiber composite materials is investigated for the detection of phosgene *** influence of environmental conditions such as humidity and temperature are examined and a detection mechanism is presented.

关键词： Polyaniline nanofibers conducting polymer amines chemical sensor phosgene

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Mass Spectrometric Analyses Reveal a Central Role for Ubiquitylation in Remodeling the Arabidopsis Proteome during Photomorphogenesis

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Molecular Plant 2017年第6期10卷 846-865页

作者： Victor Aguilar-Hernandez Do-Young Kim robert J. Stankey Mark Scalf lloyd M. Smith richard D. Vierstra Department of Biology Washington University in St. Louis Campus Box 1137 One Brookings Drive St. Louis MO 63130 USA Department of Genetics 425-G Henry Mall Department of Chemistry 1101 University Avenue University of Wisconsin-Madison Madison WI 53706 USA Advanced Bio Convergence Center Pohang Technopark Gyeong-Buk South Korea 37668

The switch from skotomorphogenesis to photomorphogenesis is a key developmental transition in the life of seed plants. While much of the underpinning proteome remodeling is driven by light-induced changes in gene expression, the proteolytic removal of specific proteins by the ubiquitin-26S proteasome system is also likely paramount. Through mass spectrometric analysis of ubiquitylated proteins affinity-purified from etiolated Arabidopsis seedlings before and after red-light irradiation, we identified a number of influential proteins whose ubiquitylation status is modified during this switch. We observed a substantial enrichment for proteins involved in auxin, abscisic acid, ethylene, and brassinosteroid signaling, peroxisome function, disease resistance, protein phosphorylation and light perception, including the phytochrome （Phy） A and phototropin photoreceptors. Soon after red-light treatment, PhyA becomes the dominant ubiquitylated species, with ubiquitin attachment sites mapped to six lysines. A PhyA mutant protected from ubiquitin addition at these sites is substantially more stable in planta upon photoconversion to Pfr and is hyperactive in driving photomorphogenesis. However, light still stimulates ubiquitylation and degradation of this mutant, implying that other attachment sites and/or proteolytic pathways exist. Collectively, we expand the catalog of ubiquitylation targets in Arabidopsis and show that this post- translational modification is central to the rewiring of plants for photoautotrophic growth.

关键词： Arabidopsis ubiquitin mass spectrometry photomorphogenesis phytochrome degradation

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Testing allometric scaling relationships in plant roots

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Forest Ecosystems 2020年第4期7卷 770-780页

作者： Qiang Deng Zhiyou Yuan Xinrong Shi T.Ryan lock robert l.Kallenbach State Key laboratory of Soil Erosion and Dryland Farming on the loess Plateau Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water ResourcesYangling 712100ShaanxiChina. University of Chinese Academy of Sciences Beijing 100049China. Institute of Soil and Water Conservation Northwest A&F UniversityYangling 712100ShaanxiChina Division of Plant Sciences College of AgricultureFoodand Natural ResourcesUniversity of Missouri108 Waters HallColumbiaMO 65211USA.

Background:Metabolic scaling theory predicts that plant productivity and biomass are both ***,this theory has not yet been tested in plant ***:In this study,we tested how metabolic scaling occurs in plants using a comprehensive plant root dataset made up of 1016 observations from natural *** generated metabolic scaling exponents by logtransformation of root productivity versus ***:Results showed that the metabolic scaling exponents of fine root(lose to 1.0 for all ecosystem types and functional *** exponents decreased in coarse roots(>2mm in diameter).Conclusions:We found isometric metabolic scaling in fine roots,a metabolically active organ similar to seedlings or *** findings also indicate a shift in metabolic scaling during plant ***,our study supports the absence of any unified single constant scaling exponent for metabolism-biomass relationships in terrestrial plants,especially for forests with woody species.

关键词： Allometry Biomass Metabolic scaling Plant roots Productivity

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Nickel oxide thin films grown by chemical deposition techniques: Potential and challenges in next-generation rigid and flexible device applications

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InfoMat 2021年第5期3卷 536-576页

作者： Mari Napari Tahmida N.Huq robert l.Z.Hoye Judith l.MacManus-Driscoll Department of Materials Science and Metallurgy University of CambridgeCambridgeUK Centre for Electronics Frontiers Zepler Institute for Photonics and NanoelectronicsUniversity of SouthamptonSouthamptonUK Department of Materials Imperial College LondonLondonUK

Nickel oxide(NiOx),a p-type oxide semiconductor,has gained significant attention due to its versatile and tunable *** has become one of the critical materials in wide range of electronics applications,including resistive switching random access memory devices and highly sensitive and selective sensor *** addition,the wide band gap and high work function,coupled with the low electron affinity,have made NiOx widely used in emerging optoelectronics and p-n *** properties of NiOx thin films depend strongly on the deposition method and *** implementation of NiOx in next-generation devices will require controllable growth and processing methods that can tailor the morphological and electronic properties of the material,but which are also compatible with flexible *** this review,we link together the fundamental properties of NiOx with the chemical processing methods that have been developed to grow the material as thin films,and with its application in electronic *** focus solely on thin films,rather than NiOx incorporated with one-dimensional or two-dimensional *** review starts by discussing how the p-type nature of NiOx arises and how its stoichiometry affects its electronic and magnetic *** discuss the chemical deposition techniques for growing NiOx thin films,including chemical vapor deposition,atomic layer deposition,and a selection of solution processing approaches,and present examples of recent progress made in the implementation of NiOx thin films in devices,both on rigid and flexible ***,we discuss the remaining challenges and limitations in the deposition of device-quality NiOx thin films with chemical growth methods.

关键词： atomic layer deposition chemical vapor deposition electronics nickel oxide solution processing thin films

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Parallel Algorithms and Software for Nuclear,Energy,and Environmental *** Ⅱ:Multiphysics Software

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Communications in Computational Physics 2012年第8期12卷 834-865页

作者： Derek Gaston luanjing Guo Glen Hansen Hai Huang richard Johnson Dana Knoll Chris Newman Hyeong Kae Park robert Podgorney Michael Tonks richard Williamson Nuclear Science and Technology Idaho National LaboratoryIdaho FallsID 83415USA Energy and Environment Science and Technology Idaho National LaboratoryIdaho FallsID 83415USA Multiphysics Simulation Technologies Dept.(1444) Sandia National LaboratoriesAlbuquerqueNM 87185USA Fluid Dynamics and Solid Mechanics Group(T-3) Los Alamos National LaboratoryLos AlamosNM 87545USA.

This paper is the second part of a two part sequence on multiphysics algorithms and *** first[1]focused on the algorithms;this part treats the multiphysics software framework and applications based on *** coupling is typically designed into the analysis application at inception,as such an application is strongly tied to a composite nonlinear solver that arrives at the final solution by treating all equations *** applicationmust also take care tominimize both time and space error between the physics,particularly if more than one mesh representation is needed in the solution *** paper presents an application framework that was specifically designed to support tightly coupled multiphysics *** Multiphysics Object Oriented Simulation Environment(MOOSE)is based on the Jacobian-freeNewton-Krylov(JFNK)method combined with physics-based preconditioning to provide the underlying mathematical structure for *** report concludes with the presentation of a host of nuclear,energy,and environmental applications that demonstrate the efficacy of the approach and the utility of a well-designed multiphysics framework.

关键词： Multiphysics simulation Jacobian-free Newton Krylov finite element applications physics-based preconditioning

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Changes in free amino acids and polyamine levels in Satsuma leaves in response to Asian citrus psyllid infestation and water stress

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Insect Science 2014年第6期21卷 707-716页

作者： Nasir S. A. Malik Jose l. Perez Madhurababu Kunta Joseph M. Patt robert l. Mangan USDA-ARS ERRC 600 E Mermaid lane Wyndmoor PA 19038-8598 USDA-ARS SPARC 2881 F&B Road College Station TX 77845 Texas A&M University-Kingsville Citrus Center 312 North International Blvd Weslaeo TX 78596 U. S. Horticultural Research laboratory 2001 South Rock Road Fort Pierce FL 34945 Subtropical Horticultural Research Station 13601 Old Coulter Road Miami FL 33158 USDA-ARS 2413 E. Hwy 83 Weslaco TX 78596 USA

The effects of biotic and abiotic stresses on changes in amino acids and polyamine levels in Satsuma orange （Citrus unshiu; cultivar Owari） leaves were inves- tigated. Asian citrus psyllids Diaphorina citri （Kuwayama）（ACP） infestation was used to induce biotic stress while a water deficit was imposed to induce abiotic stress. Potted trees were infested by placing 50 psyllids on 3 citrus leaves enclosed in nylon mesh bags for 5 d. A parallel set of plants were kept water stressed by maintaining the soil at 20% water holding capacity for 5 d. levels of total free amino acids were higher in water stressed and ACP infested leaves. Polyamine putrescine increased in infested leaves but not in water stressed leaves. Proline was the most abundant amino acid and its levels significantly increased by both biotic and abiotic stresses. Proline levels in infested leaves were significantly higher than the water stressed leaves. Histidine, methionine, asparagine, arginine, serine, and leucine levels also increased significantly in infested leaves, but in water stressed leaves only leucine, methionine, and threonine increased. levels of amino acids, such as tyrosine, isoleucine, phenylalanine, glutamic acid, and alanine, declined in infested leaves. Under water stress asparagine, phenylalanine, serine, and histidine also declined compared to controls. This indicates that while proteolysis occurred under both stresses, metabolic conversion of amino acids was different under the two stresses. In ACP infested leaves some amino acids may be used as feeding material and/or converted into secondary metabolites for defense.

关键词： amino acids citrus Diaphorina citri polyamines

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Routine use of thiopurines in maintaining remission in pediatric Crohn's disease

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World Journal of Gastroenterology 2014年第27期20卷 9185-9190页

作者： Brendan M Boyle Michael D Kappelman richard B Colletti robert N Baldassano David E Milov Wallace V Crandall Nationwide Children’s Hospital Department of Pediatrics University of North Carolina at Chapel Hill University of Vermont Children’s Hospital of Philadelphia Nemours Children’s Clinic

AIM: To evaluate the effectiveness of thiopurines in maintaining steroid-free remission in routine clinical practice.

关键词： Crohn's disease Pediatric Remission Thiopurines Mercaptopurine

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Towards real-time detection of wastewater in surface waters using fluorescence spectroscopy

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Journal of Environmental Sciences 2019年第12期31卷 195-202页

作者： Ye Z.Yang Nicolas M.Peleato Raymond l.legge robert C.Andrews Department of Ciuil and Mineral Engineering University of Toronto35 St.George St.TorontoOntario M5S 1A4Canada School of Engineering Uniuersity of British Columbia Okanagan1137 Alwmni AueKeloiunaBritish Columbia V1V 1V7Canada Department of Chemical Engineering University of Waterloo200 University Ave.WWaterlooOntario N2L 3G1Canada

The presence of municipal wastewater at the intake of a major drinking water treatment facility located on lake Ontario was examined using fluorescence data collected during a period of continuous *** addition,controlled mixing of lake water and wastewater sampled from a local treatment facility were conducted using a bench-scale fluorescence system to quantify observed changes in natural organic *** linear regression was applied to components derived from parallel factors *** resulting mean absolute error for predicted wastewater level was 0.22%(V/V,wastewater/lake water),indicating that wastewater detection at below 1.0%(V/V)was *** of sucralose,a wastewater indicator,were conducted for treated wastewater as well as surface water collected at two intake locations on lake *** suggested minimal wastewater contribution at the drinking water intake.A wastewater detection model using a moving baseline was developed and applied to continuous fluorescence data collected at one of the drinking water intakes,which agreed well with sucralose ***,the simulated addition of 1.0%(V/V)of wastewater/wastewater was detectable in 89%of samples analyzed,demonstrating the utility of fluorescence-based wastewater monitoring.

关键词： Excitation emission matrices Parallel factors analysis Natural organic matter Source water monitoring Wastewater impact Water quality assessment

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Viral infections and cell cycle G2/M regulation

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Cell Research 2005年第3期15卷 143-149页

作者： richard Y. ZHAO,robert T. ElDER Children's Memorial Research Center Northwestern University Feinberg School of Medicine Chicago Il 60614 USA

Progression of cells from G2 phase of the cell cycle to mitosis is a tightly regulated cellular process that requires activation of the Cdc2 kinase, which determines onset of mitosis in all eukaryotic cells. In both human and fission yeast (Schizosaccharomyces pombe) cells, the activity of Cdc2 is regulated in part by the phosphorylation status of tyrosine 15 (Tyr15) on Cdc2, which is phosphorylated by Wee1 kinase during late G2 and is rapidly dephosphorylated by the Cdc25 tyrosine phosphatase to trigger entry into mitosis. These Cdc2 regulators are the downstream targets of two well- characterized G2/M checkpoint pathways which prevent cells from entering mitosis when cellular DNA is damaged or when DNA replication is inhibited. Increasing evidence suggests that Cdc2 is also commonly targeted by viral proteins, which modulate host cell cycle machinery to benefit viral survival or replication. In this review, we describe the effect of viral protein R (Vpr) encoded by human immunodeficiency virus type 1 (HIV-1) on cell cycle G2/M regulation. Based on our current knowledge about this viral effect, we hypothesize that Vpr induces cell cycle G2 arrest through a mechanism that is to some extent different from the classic G2/M checkpoints. One the unique features distinguishing Vpr-induced G2 arrest from the classic checkpoints is the role of phosphatase 2A (PP2A) in Vpr-induced G2 arrest. Interestingly, PP2A is targeted by a number of other viral proteins including SV40 small T antigen, polyomavirus T antigen, HTlV Tax and adenovirus E4orf4. Thus an in-depth understanding of the molecular mechanisms underlying Vpr-induced G2 arrest will provide additional insights into the basic biology of cell cycle G2/M regulation and into the biological significance of this effect during host-pathogen interactions.

关键词： HIV-1 Vpr cell cycle G2/M regulation DNA damage DNA replication checkpoints viral infections fission yeast Schizosaccharomyces pombe.

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