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Enhanced thermal transport across monolayer MoS2

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Nano Research 2018年第4期11卷 2173-2180页

作者： Miguel Goni j.a Yang aaron j. Schmidt 110 Cummington mall Mechanical Engineering Boston University Boston 02115 USA

Characterizing the thermal properties of MoS2 is important for the design of electronic devices based on this material. We used frequency domain thermoreflectance to study the cross-plane thermal transport in mechanically exfoliated MoS2 samples supported on SiO2 and muscovite mica substrates. The thickness of MoS2 ranged between one and five layers, and the MoS2 layers were sandwiched between a metal layer and the substrate. In the case of mica, heat transport into the substrate remained the same whether or not a monolayer of MoS2 was present, whereas, for SiO2, heat transport was reduced by surface roughness. We observed a significant improvement in heat transport across monolayer MoS2 as compared to few layer MoS2. For MoS2 on SiO2, the effective thermal interface conductance was improved by more than three times if a monolayer was used. For MoS2 on mica, the thermal interface conductance was approximately two times better for monolayer MoS2. This implies that monolayer MoS2 has superior thermal properties and can be used in electronic devices as an intermediate layer between two materials. Additionally, we also report on the measurement of anisotropic thermal conductivity in bulk MoS2 and mica.

关键词： MoS2 cross plane thermal transport,frequency domain thermoreflectance,muscovite mica,SiO2

Ectomycorrhizal and Saprotrophic Fungal Communities Vary Across mm-Scale Soil Microsites Differing in Phosphatase Activity

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Pedosphere 2019年第3期29卷 344-359页

作者： aaron GODIN Denise BROOKS Sue j. GRAYSTON Melanie D. j.NES Biology Department University of British Columbia Okanagan campus Kelowna V1V 1V7 (Canada) Department of Forest & Conservation Sciences Faculty of Forestry University of British Columbia Vancouver V6T 1Z4 (Canada)

To understand nutrient cycling in soils, soil processes and microorganisms need be better characterized. To determine whether specific trophic groups of fungi are associated with soil enzyme activity, we used soil imprinting to guide mm-scale sampling from microsites with high and low phosphatase activities in birch/Douglas-fir stands. Study 1 involved sampling one root window per site at 12 sites of different ages(stands);study 2 was conducted at one of the stem-exclusion stands, at which 5 root windows had been installed. Total fungal and ectomycorrhizal(EM) fungal terminal-restriction fragment length polymorphism(TRFLP)fingerprints differed between high-and low-phosphatase activity microsites at 8 of 12 root windows across 12 sites. Where differences were detected, fewer EM fungi were detected in high-than low-phosphatase activity microsites. Using 5 root windows at one site,next-generation sequencing detected similar fungal communities across microsites, but the ratio of saprotrophic to EM fungal reads was higher in high-phosphatase activity microsites in the two windows that had low EM fungal richness. In windows with differences in fungal communities, both studies indicated that EM fungi were less successful than saprotrophic fungi in colonizing fine-scale,organic matter-rich microsites. Fine-scale sampling linked with in situ detection of enzyme activity revealed relationships between soil fungal communities and phosphatase activity that could not be observed at the scales employed by conventional approaches, thereby contributing to the understanding of fine-scale phosphorus cycling in forest soils.

关键词： ectomycorrhizae fine scale fungal communities phosphatase root windows saprotrophic fungi soil imprinting

Comparisons of j.ULE 1 rocket thermospheric wind observations in high latitudes with GITM simulations

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Science China(Technological Sciences) 2017年第3期60卷 412-418页

作者： DENG Yue LARSEN Miguel F RIDLEY aaron j.ZHAN TianYu Department of Physics University of Texas at Arlington Department of Physics Clemson University Center for Space Environment Modeling The University of Michigan

4 Summary and conclusion The j.ULE sounding rocket 1 experiment was carried out at Poker Flat Research Range in Alaska around 1200 UT on March 27th,2003 with two instrumented rockets and one chemical tracer *** the released TMA trails,neutral wind measurements from approximately 85 to 160 km altitude showed a vertically propagating wave and a j.t structure around 120 km *** shears appeared at the bottom side of the j.t with Richardson numbers close to or smaller than the critical value of 0.25,which implies the possible existence of Kelvin-Helmholtz instabilities caused by the vertical shear in the fast flows.

关键词： target tracking parallel vision processor MRID skipping searching image processing

Co-author Weighting in Bibliometric Methodology and Subfields of a Scientific Discipline

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j.urnal of Data and Information Science 2020年第3期5卷 84-96页

作者： Lawrence Smolinsky aaron j.Lercher Department of Mathematics Louisiana State UniversityBaton RougeLA 70803USA Middleton Library Louisiana State UniversityBaton RougeLA 70803USA

Purpose: To give a theoretical framework to measure the relative impact of bibliometric methodology on the subfields of a scientific discipline, and how that impact depends on the method of evaluation used to credit individual scientists with citations and publications. The authors include a study of the discipline of physics to illustrate the method. Indicators are introduced to measure the proportion of a credit space awarded to a subfield or a set of ***/methodology/approach: The theoretical methodology introduces the notion of credit spaces for a discipline. These quantify the total citation or publication credit accumulated by the scientists in the discipline. One can then examine how the credit is divided among the subfields. The design of the physics study uses the American Physical Society print j.urnals to assign subdiscipline classifications to articles and gather citation, publication, and author information. Credit spaces for the collection of Physical Review j.urnal articles are computed as a proxy for ***: There is a substantial difference in the value or impact of a specific subfield depending on the credit system employed to credit individual *** limitations: Subfield classification information is difficult to obtain. In the illustrative physics study, subfields are treated in groups designated by the Physical Review j.urnals. While this collection of articles represents a broad part of the physics literature, it is not all the literature nor a random *** implications: The method of crediting individual scientists has consequences beyond the individual and affects the perceived impact of whole subfields and institutions. Originality/value: The article reveals the consequences of bibliometric methodology on subfields of a disciple by introducing a systematic theoretical framework for measuring the consequences.

关键词： Citation analysis Bibliometrics Research evaluation Co-author

Factors affecting use of ballistics gelatin in laboratory studies of bacterial contamination in proj.ctile wounds

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Military Medical Research 2018年第4期5卷 304-313页

作者： j.ssica j. Evans aaron Bost Karim H. Muci-Küchler Linda C. DeVeaux Biomedical Engineering Program South Dakota School of Mines and Technology Mechanical Engineering Department South Dakota School of Mines and Technology Department of Biology New Mexico Institute of Mining and Technology

Background: Ballistics gelatin is a common tissue surrogate used in bacterial contamination models for proj.ctile wounds. Although these studies have demonstrated that bacteria are transferred from the surface of the gelatin to the wound track by a proj.ctile, quantifiable results have been inconsistent and not repeatable in successive ***: In this study, five areas of a typical contamination model in which bacterial recovery or survival are affected were identified for optimization. The first was a contaminated "skin" surrogate, where the novel use of vacuum filtration of a bacterial culture and buffer onto filter paper was employed. The other possibly problematic areas of the bacterial distribution model included the determination of bacterial survival when the contamination model is dried, survival in solid and molten gelatin, and the effect of high-intensity lights used for recording high-speed ***: Vacuum filtration of bacteria and buffer resulted in a consistent bacterial distribution and recovery. The use of phosphate buffer M9(pH 7) aided in neutralizing the ballistics gelatin and improving bacterial survival in solid gelatin. Additionally, the use of high-intensity lights to record high-speed video and the use of a 42℃ water bath to melt the gelatin were found to be bactericidal for gram-positive and gram-negative ***: Multiple areas of a typical contamination model in which bacterial survival may be impeded were identified, and methods were proposed to improve survival in each area. These methods may be used to optimize the results of bacterial contamination models for medical applications, such as understanding the progression of infection in penetrating wounds and to identify possible sources of contamination for forensic purposes.

关键词： Ballistics gelatin Wound Contamination Bacterial model

Arabidopsis FtsZ2-1 and FtsZ2-2 Are Functionally Redundant, But FtsZ-Based Plastid Division Is Not Essential for Chloroplast Partitioning or Plant Growth and Development

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Molecular Plant 2009年第6期2卷 1211-1222页

作者： aaron j. Schmitz j.nathan M. Glynn Bradley j.S.C. Olson Kevin D. Stokes Katherine W. Osteryoung Department of Plant Biology 166 Plant Biology Bldg Michigan State University East Lansing MI 48824-1312 USA Cell and Molecular Biology Program Michigan State University East Lansing MI 48824 USA Department of Energy-Plant Research Laboratory Michigan State University East Lansing MI 48824 USA Genetics Program Michigan State University East Lansing MI 48824 USA Biochemistry and Molecular Biology Program Michigan State University East Lansing MI 48824 USA Present address: The Salk Institute for Biological Studies Plant Molecular and Cellular Biology Laboratory La Jolla CA 92037 USA Present address: Mycobacteria and Brucella Section NVSL/APHIS/USDA 1920 Dayton Ave Ames IA 50010 USA

FtsZ1 and FtsZ2 are phylogenetically distinct families of FtsZ in plants that co-localize to mid-plastid rings and facilitate division of chloroplasts. In plants, altered levels of either FtsZ1 or FtsZ2 cause dose-dependent defects in chloroplast division; thus, studies on the functional relationship between FtsZgenes require careful manipulation of FtsZ levels in vivo. To define the functional relationship between the two FtsZ2 genes in Arabidopsis thaliana, FtsZ2-1 and FtsZ2-2, we expressed FtsZ2-1 in an ftsZ2-2 null mutant, and vice versa, and determined whether the chloroplast division defects were rescued in plants expressing different total levels of FtsZ2. Full rescue was observed when either the FtsZ2-1 or FtsZ2-2 level approximated total FtsZ2 levels in wild-type （WT）. Additionally, FtsZ2-2 interacts with ARC6, as shown previously for FtsZ2- 1. These data indicate that FtsZ2-1 and FtsZ2-2 are functionally redundant for chloroplast division in Arabidopsis. To rigorously validate the requirement of each FtsZ family for chloroplast division, we replaced FtsZ1 with FtsZ2 in vivo, and vice versa, while maintaining the FtsZ level in the transgenic plants equal to that of the total level in WT. Chloroplast division defects were not rescued, demonstrating conclusively that FtsZ1 and FtsZ2 are non-redundant for maintenance of WT chloroplast numbers. Finally, we generated ftsZtriple null mutants and show that plants completely devoid of FtsZ protein are viable and fertile. As plastids are presumably essential organelles, these findings suggest that an FtsZ-independent mode of plastid partitioning may occur in higher plants.

关键词： Chloroplast plastid division FtsZ ARC6 PDV1.

Dietary fibre effects and the interplay with exogenous carbohydrases in poultry nutrition

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Animal Nutrition 2024年第1期16卷 231-240页

作者： Michael R.Bedford Birger Svihus aaron j.Cowieson AB Vista Feed Ingredients Ltd MarlboroughUnited Kingdom Norwegian University of Life Sciences ÅsNorway DSM Nutritional Products KaiseraugstSwitzerland

A comprehensive understanding of the role of dietary fibre in non-ruminant animal production is *** and conflated definitions of fibre coupled with significant analytical complexity,interact with poorly defined host and microbiome *** fibre is known to influence gut development,feed intake and passage rate,nutrient absorption,microbiome taxonomy and function,gut p H,endogenous nutrient loss,environmental sustainability,animal welfare and *** significant gaps persist in our understanding of fibre in non-ruminant animal production,there is substantial interest in optimizing the fibre fraction of feed to induce high value phenotypes such as improved welfare,live performance and to reduce the environmental footprint of animal production *** order to achieve these aspirational goals,it is important to tackle dietary fibre with the same level of scrutiny as is currently done for other critical nutrient classes such as protein,minerals and *** chemical,mechanical and nutritional role of fibre must be explored at the level of monomeric sugars,oligosaccharides and polysaccharides of varying molecular weight and decoration,and this must be in parallel to standardisation of analytical tools and definitions for *** further complicate subj.ct,exogenous carbohydrases recognise dietary fibre as a focal substrate and have varying capacity to generate lower molecular weight carbohydrates that interact differentially with the host and the enteric *** short review article will explore the interactive space between dietary fibre and exogenous carbohydrases and will include their nutritional and health effects with emphasis on functional development of the gut,microbiome modulation and host metabolism.

关键词： Fibre Carbohydrase Nutrition Microbiome Gastro-intestinal development Feed

The impact of salps(Salpa thompsoni)on the Antarctic krill population(Euphausia superba):an individual-based modelling study

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Ecological Processes 2023年第1期12卷 680-695页

作者： Bruno Walter Pietzsch aaron Schmidt j.rgen Groeneveld Dominik Bahlburg Bettina Meyer Uta Berger Faculty of Environmental Sciences Institute of Forest Growth and Forest Computer SciencesTechnische Universität Dresden01062 DresdenGermany Department of Ecological Modelling Helmholtz Centre for Environmental Research-UFZLeipzigGermany Section Polar Biological Oceanography Alfred Wegener Institute Helmholtz Centre for Polar and Marine ResearchBremerhavenGermany Institute for Chemistry and Biology of the Marine Environment(ICBM) Carl-Von-Ossietzky UniversityOldenburgGermany Helmholtz Institute for Marine Functional Biodiversity(HIFMB) OldenburgGermany

Background Krill(Euphausia superba)and salps(Salpa thompsoni)are key macrozooplankton grazers in the Southern Ocean ***,due to differing habitat requirements,both species previously exhibited little spatial *** ongoing climate change-induced seawater temperature increase and regional sea ice loss,salps can now extend their spatial distribution into historically krill-dominated areas and increase rapidly due to asexual reproduction when environmental conditions are *** the potential effects on krill is crucial,since krill is a species of exceptional trophic significance in the Southern Ocean food *** impacts on krill could trigger cascading effects on its predators and *** address this question,we combined two individual-based models on salps and krill,which describe the whole life cycle of salp individuals and the dynamic energy budget of individual *** resulting new model PEKRIS(PErformance of KRIll ***)simulates a krill population for 100 years under varying chlorophyll-a concentrations in the presence or absence of *** All of the investigated krill population properties(abundance,mean length,and yearly egg production)were significantly impacted by the presence of *** the other hand,salp density was not impacted if krill were *** medians of krill population properties deviated during variable maximum chlorophyll-a density per year when salps were introduced by−99.9%(−234 individuals per 1000 m3)for krill density,−100%(−22,062 eggs per 1000 m3)for krill eggs and−0.9%(−0.3 mm)for mean length of *** If both species compete for the same food resource in a closed space,salps seem to inhibit krill *** simulation studies should investigate whether this effect prevails if different phytoplankton sizes and consumption preferences of krill are ***,direct predation of the two species or consumption of krill fecal pellets by salps could c

关键词： Euphausia superba Salpa thompsoni Individual-based model Food competition Population dynamics DEB theory

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Calculation and interpretation of classical turning surfaces in solids

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npj.Computational Materials 2021年第1期7卷 229-238页

作者： aaron D.Kaplan Stewart j.Clark Kieron Burke j.hn P.Perdew Department of Physics Temple UniversityPhiladelphiaPA 19122USA Centre for Materials Physics Durham UniversityDurham DH13LEUK Departments of Chemistry and Physics University of CaliforniaIrvineCA 92697USA Departments of Physics and Chemistry Temple UniversityPhiladelphiaPA 19122USA

Classical turning surfaces of Kohn–Sham potentials separate classically allowed regions(CARs)from classically forbidden regions(CFRs).They are useful for understanding many chemical properties of molecules but need not exist in solids,where the density never decays to *** equilibrium geometries,we find that CFRs are absent in perfect metals,rare in covalent semiconductors at equilibrium,but common in ionic and molecular *** all materials,CFRs appear or grow as the internuclear distances are uniformly *** can also appear at a monovacancy in a *** with several approximate density functionals and codes confirm these behaviors.A classical picture of conduction suggests that CARs should be connected in metals,and disconnected in wide-gap insulators,and is confirmed in the limits of extreme compression and ***,many semiconductors have no CFR at equilibrium,a key finding for density functional ***,a strong correlation with insulating behavior can still be ***,equilibrium bond lengths for all cases can be estimated from the bond type and the sum of the classical turning radii of the free atoms or ions.

关键词： turning solids expanded