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From thermal conductive to thermal insulating:Effect of carbon vacancy content on lattice thermal conductivity of ZrC_(x)

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Journal of Materials Science & Technology 2021年第23期82卷 105-113页

作者： Yue Zhou William g.Fahrenholtz Joseph graham gregory E.Hilmas Department of Materials Science and Engineering Missouri University of Science and TechnologyRollaMO 65409USA

Lattice thermal conductivities of zirconium carbide(ZrC_(x),x=1,0.75 and 0.5)ceramics with different carbon vacancy concentrations were calculated using a combination of first-principles calculations and the Debye-Callaway *** gruneisen parameters,Debye temperatures,and phonon group velocities were deduced from phonon dispersions of ZrC_(x) determined using first-principles *** addition,the effects of average atomic mass,grain size,average atomic volume and Zr isotopes on the lattice thermal conductivities of ZrC_(x) were analyzed using phonon scattering *** lattice thermal conductivity decreased as temperature increased for ZrC,ZrC_(0.75) and ZrC_(0.5)(Zr2 C),and decreased as carbon vacancy concentration ***,ZrC_(x) can be tailored from a thermal conducting material for ZrC with high lattice thermal conductivity to a thermal insulating material for ZrC_(0.5) with low lattice thermal ***,it opens a window to tune the thermal properties of ZrC_(x) by controlling the carbon vacancy content.

关键词： Zirconium carbide Lattice thermal conductivity Theoretical study First-principle calculations

Spatio-temporal patterns and changes in environmental attitudes and place attachment in gauteng, South Africa

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geo-Spatial Information Science 2021年第4期24卷 666-677页

作者： Simangele Dlamini Solomon g.Tesfamichael gregory D.Breetzke Tholang Mokhele Department of geography Environmental Management and Energy StudiesUniversity of JohannesburgJohannesburgSouth Africa geospatial Analytics eResearch Knowledge CentreHuman Sciences Research CouncilPretoriaSouth Africa Department of geography Geoinformatics and MeteorologyUniversity of PretoriaPretoriaSouth Africa

In this study,we employed a number of geospatial techniques to examine the spatiotemporal patterns and changes of environmental attitudes and place attachment values in the gauteng province of South *** data were obtained from the gauteng City Region Observatory’s Quality of Life Survey collected at three separate points in time,namely 2013,2015,and *** indicated that wards(smallest administrative and analysis units)located on the urban periphery of gauteng,which are generally less affluent,largely held more negative environmental attitudes and place attachment values during the three time *** contrast,centrally located wards,which are generally more affluent,expressed more positive environmental attitudes but less place attachment values,especially in *** findings of this research not only highlight the complex spatio-temporal distribution of environmental attitudes and place attachment values throughout gauteng but also empha-size the need for spatially targeted state interventions for future environmental planning within the province.

关键词： Spatio-temporal changes environmental attitudes place attachment gauteng spatial patterns

Polyvinylchloride surface modified with polymer brushes for reduced protein,cell and bacteria attachment

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Biosurface and Biotribology 2023年第4期9卷 187-198页

作者： Rashed Almousa Dong Xie Jiliang Li gregory g.Anderson Weldon School of Biomedical Engineering Purdue UniversityWest LafayetteIndianaUSA Department of Medical Equipment Technology College of Applied Medical SciencesMajmaah UniversityAl-MajmaahSaudi Arabia Department of Biomedical Engineering Indiana University-Purdue University at IndianapolisIndianapolisIndianaUSA Department of Biology Purdue School of ScienceIndiana University-Purdue University at IndianapolisIndianapolisIndianaUSA

The objective of this study was to coat negatively charged polymer brushes by a covalent bond onto the surface of polyvinylchloride using a simple conventional surface free radical polymerisation *** coated surfaces were assessed with contact angle,protein adsorption,cell adhesion,and bacterial *** serum albumin and bovine fibrinogen were used for protein adsorption *** fibroblast(NIH-3T3)cells and Pseudomonas aeruginosa were used to assess surface *** show that the surface modified with all the attached polymers exhibited significantly reduced contact angle,protein adsorption,and cell as well as bacterial adhesion among which the negatively charged polymers showed extremely low values in all the *** negatively charged polymer shows its contact angle at 5°as compared to 70°for original *** bovine serum albumin,bovine fibrinogen,3T3 adhesion,and *** adhesion were 93%,84%,92%,and 92%lower than the original PVC,***,the polyvinylchloride surface coated with negatively charged polymer brushes exhibited a hydrogel-like *** results indicate that coating a polyvinylchloride surface with acrylic acids using a simple surface-initiated free radical polymerisation and then converting those to negatively charged salts can be an effective and efficient route for fouling-resistant applications.

关键词： polymer surface

Thermal and microstructural characterization of a novel ductile cast iron modified by aluminum addition

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International Journal of Minerals,Metallurgy and Materials 2020年第2期27卷 190-199页

作者： gülsah Aktas Celik Maria-Ioanna TTzini Seyda Polat SHakan Atapek gregory NHaidemenopoulos Department of Metallurgical and Materials Engineering Kocaeli UniversityKocaeli 41001Turkey Laboratory of Materials Department of Mechanical EngineeringUniversity of ThessalyVolos 38334Greece Department of Mechanical Engineering Khalifa University of Science and TechnologyAbu Dhabi 127788UAE

In high-temperature applications,like exhaust manifolds,cast irons with a ferritic matrix are mostly ***,the increasing demand for higher-temperature applications has led manufacturers to use additional expensive materials such as stainless steels and Ni-resist austenitic ductile cast ***,in order to meet the demand while using low-cost materials,new alloys with improved high-temperature strength and oxidation resistance must be *** this study,thermodynamic calculations with Thermo-Calc software were applied to study a novel ductile cast iron with a composition of 3.5wt%C,4wt%Si,1wt%Nb,0‒4wt%*** designed compositions were cast,and thermal analysis and microstructural characterization were performed to validate the *** lowest critical temperature of austenite to pearlite eutectoid transformation,i.e.,A1,was calculated,and the solidification sequence was *** calculations and experimental data revealed the importance of aluminum addition,as the A1 increased by increasing the aluminum content in the alloys,indicating the possibility of utilizing the alloys at higher *** experimental data validated the transformation temperature during solidification and at the solid state and confirmed the equilibrium phases at room temperature as ferrite,graphite,and MC-type carbides.

关键词： ductile cast iron alloy design Thermo-Calc high-temperature material

The role of endoscopy in the management of hereditary diffuse gastric cancer syndrome

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World Journal of gastroenterology 2019年第23期25卷 2878-2886页

作者： Shria Kumar Jessica M Long gregory g ginsberg Bryson W Katona Division of gastroenterology University of Pennsylvania Perelman School of MedicinePhiladelphiaPA 19104United States Division of Hematology and Oncology University of Pennsylvania Perelman School of MedicinePhiladelphiaPA 19104United States

Hereditary diffuse gastric cancer(HDgC) syndrome is an inherited cancer risk syndrome associated with path-ogenic germline CDH1 variants. given the high risk for developing diffuse gastric cancer, CDH1 carriers are recommended to undergo prophylactic total gastrectomy for cancer risk reduction. Current guidelines recommend upper endoscopy in CDH1 carriers prior to surgery and then annually for individuals deferring prophylactic total *** of individuals from HDgC families without CDH1 pathogenic variants remains less clear, and management of families with CDH1 pathogenic variants in the absence of a family history of gastric cancer is particularly problematic at present. Despite adherence to surveillance protocols, endoscopic detection of cancer foci in HDgC is suboptimal and imperfect for facilitating decision-making. Alternative endoscopic modalities, such as chromoendoscopy,endoscopic ultrasound, and other non-white light methods have been utilized,but are of limited utility to further improve cancer detection and risk stratification in HDgC. Herein, we review what is known and what remains unclear about endoscopic surveillance for HDgC, among individuals with and without germline CDH1 pathogenic variants. Ultimately, the use of endoscopy in the management of HDgC remains a challenging arena, but one in which further research to improve surveillance is crucial.

关键词： CDH1 gene Hereditary diffuse gastric cancer gastric cancer Endoscopic screening Endoscopy

Assessing risks from mining-induced ground movements near gas wells

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International Journal of Mining Science and Technology 2020年第1期30卷 11-16页

作者： Christopher Mark gregory M.Rumbaugh Mine Safety and Health Administration PittsburghPAUSA

The proliferation of unconventional gas well development in the Northern Appalachian coalfields has raised a number of mine safety *** wells,which extract gas from deep shale formations,are characterized by gas volumes and pressures that are significantly higher than those observed at many conventional *** gas is composed largely of methane as well as other *** of planned and actively producing wells penetrate protective coal pillars or barriers within active mine boundaries,including chain pillars located between longwall *** released from a well damaged by mining-induced ground movements could pose a risk to miners by flowing into the mine *** mining-induced ground movements that may cause well damage include conventional subsidence,non-conventional subsidence(*** plane slip),pillar failure,and floor *** paper describes the known risk factors for each of the four failure *** includes a framework that can guide the risk assessment process when mining takes place near gas or oil wells.

关键词： gas well Subsidence Coal protection pillar Risk matrix Longwall mining

Thermodynamic analysis of metal segregation in dual phase high entropy ceramics

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Journal of Materiomics 2024年第4期10卷 889-895页

作者： Steven M.Smith II William g.Fahrenholtz gregory E.Hilmas Stefano Curtarolo Missouri University of Science and Technology Materials Science and Engineering DepartmentRollaMO65409USA Duke University Department of Mechanical Engineering and Materials ScienceDurhamNC27708USA Duke University Center of Autonomous Materials DesignDurhamNC27708USA

Equilibrium gibbs'free energy calculations were used to determine metal segregation trends between boride and carbide solid solutions containing two metals that are relevant to dual phase high entropy *** model predicted that Ti had the strongest tendency to segregate to the boride phase followed by Zr,Nb,Mo,V,Hf,and Ta,which matches experimental results of measured *** ratio of a metal in the carbide phase to the content of the same metal in the corresponding metal boride had a linear trend with the change in standard gibbs'free energy of reaction for a metal carbide reacting with B_(4)C to produce its corresponding metal boride and *** proposed model was used to predict the changes in standard gibbs'free energy for CrC→CrB_(2) to be−260 kJ and WC→WB_(2) to be 148 kJ,which indicates that Cr has the strongest segregation to the boride and W has the strongest segregation to the *** proposed model can be used to estimate the segregation of metals in dual phase high entropy boride-carbide ceramics of any boride/carbide ratio or metal content.

关键词： Dual phase High entropy ceramic Boride Carbide Thermodynamics

Synthesis of the C50 diastereomers of the C33–C51 fragment of stambomycin D

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Organic Chemistry Frontiers 2022年第2期9卷 445-449页

作者： Yongchen Wang Venkaiah Chintalapudi Haraldur g.gudmundsson gregory L.Challis Edward A.Anderson Chemistry Research Laboratory University of Oxford12 Mansfield RoadOxfordOX13TAUK Department of Chemistry and Warwick Integrative Synthetic Biology Centre University of WarwickCoventryCV47ALUK Department of Biochemistry and Molecular Biology and ARC Centre of Excellence for Innovations in Peptide and Protein Science Biomedicine Discovery InstituteMonash UniversityClaytonVictoria 3800Australia

As products of genome mining,the stereochemical assignment of the macrolide antibiotics stambomycins A-D has been made on the basis of sequence analysis of the associated polyketide synthase,aside from two stereocentres at C28 and *** we describe syntheses of the two C50 diastereomers of the C33-C51 region of the stambomycins,which support the PKS-based configurational assignment,and establish a strategy suitable for access to the extended stambomycin framework.

关键词： stereo assignment centre

Intermittent chaos for ergodic light trapping in a photonic fiber plate

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Light(Science & Applications) 2016年第1期5卷 209-215页

作者： Marina Mariano gregory Kozyreff Luis g gerling Pablo Romero-gomez Joaquim Puigdollers Jorge Bravo-Abad Jordi Martorell ICFO-Institut de Ciencies Fotoniques The Barcelona Institute of Science and TechnologyCastelldefels(Barcelona)08860Spain Département de Physique UniversitéLibre de Bruxelles(ULB)Campus de la PlaineBruxelles B-1050Belgium Departament Enginyeria Electrònica Universitat Politècnica de CatalunyaBarcelona 08034Spain Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center(IFIMAC) Universidad Autónoma de MadridMadrid 28049Spain Departament de Física Universitat Politècnica de CatalunyaTerrassa 08222Spain

Extracting the light trapped in a waveguide,or the opposite effect of trapping light in a thin region and guiding it perpendicular to its incident propagation direction,is essential for optimal energetic performance in illumination,display or light harvesting *** we demonstrate that the paradoxical goal of letting as much light in or out while maintaining the wave effectively trapped can be achieved with a periodic array of interpenetrated fibers forming a photonic fiber *** entering perpendicular to that plate may be trapped in an intermittent chaotic trajectory,leading to an optically ergodic *** fabricated such a photonic fiber plate and showed that for a solar cell incorporated on one of the plate surfaces,light absorption is greatly *** this,we found the unexpected result that a more chaotic photon trajectory reduces the production of photon scattering entropy.

关键词： chaos ergodicity fiber light-guiding plate light harvesting light trapping