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Tribologically induced nanostructural evolution of carbon materials: A new perspective

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Friction 2024年第1期12卷 144-163页

作者： Guilherme Oliveira NEVES Nicolás ARAYA Diego Berti SALVARO Thiago de Souza LAMIM Renan Oss GIACOMELLI Cristiano BINDER Aloisio Nelmo klein Josédaniel Biasoli de MELLO Laboratório de Materiais Universidade Federal de Santa CatarinaSanta Catarina 88040-900Brazil Departamento de Ingeniería Mecánica Facultad de IngenieríaUniversidad del Bío-BíoConcepcion 4070-386Chile Universidad de Concepción Concepcion 4070-386Chile SENAI Innovation Institute for Laser Processing Santa Catarina 89218-153Brazil Universidade Federal de Uberlândia Minas Gerais 38408-100Brazil

Carbon-based solid lubricants are excellent options to reduce friction and wear,especially with the carbon capability to adopt different allotropes *** the macroscale,these materials are sheared on the contact along with debris and contaminants to form tribolayers that govern the tribosystem *** a recently developed advanced Raman analysis on the tribolayers,it was possible to quantify the contactinduced defects in the crystalline structure of a wide range of allotropes of carbon-based solid lubricants,from graphite and carbide-derived carbon particles to multi-layer graphene and carbon *** addition,these materials were tested under various dry sliding conditions,with different geometries,topographies,and solid-lubricant application *** of the initial tribosystem conditions and allotrope level of atomic ordering,there is a remarkable trend of increasing the point and line defects density until a specific saturation limit in the same order of magnitude for all the materials tested.

关键词： carbon nanostructures tribology Raman spectroscopy defects quantification tribolayer solid lubrication

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每当我找到生命的意义，它就又变了

作者： (美)丹尼尔·克莱恩(daniel klein)

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和伊壁鸠鲁一起旅行

Dehydrated Natural Feed for Cats: Influence on Apparent Digestibility Coefficient, Feces Scores, and Serum Immune, Antioxidant, and Metabolic Biomarkers

作者： (美)丹尼尔·克莱恩(daniel klein)

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Food and Nutrition Sciences 2024年第7期15卷 594-611页

作者： Bruno Giorgio de Oliveira Cécere Guilherme Luiz Deolindo Bianca F. Bissacotti Priscila Marquezin Copetti Maria Rosa Chitolina Schetinger Bruna klein Matheus Delamea Baldissera Thiago Pereira Ribeiro Walter Hugo Cuelho Suarez daniel Pigatto Monteiro Aleksandro Schafer Da Silva Graduate Multicenter Program in Biochemistry and Molecular Biology University of the State of Santa Catarina Lages Brazil Department of Biochemistry and Molecular Biology Universidade Federal de Santa Maria (UFSM) Santa Maria Brazil Department of Animal Science Universidade Federal de Santa Maria (UFSM) Chapec Brazil Department of Health Science Universidade Franciscana (UFN) Santa Maria Brazil Department of Animal Nutrition Tectron-Tecnologia e Inovao Toledo Brazil

The present study aimed to determine whether natural dehydrated feed (DNF) can replace dry extruded feed while preserving the required daily intake, nutrient digestibility and benefits for immunity and antioxidant response in cats. The animals were divided into two groups of seven animals each. One group received DNF, and the other consumed commercial extruded dry feed (DCF). The experiment lasted 45 days and we measured daily consumption and collected blood and feces samples. The animals in the DNF group showed greater digestibility of fiber and mineral matter than DCF. Cats in the DNF group had a higher volume of feces. DNF cats had lower leukocyte and granulocyte counts and cholesterol levels. Serum enzymatic antioxidant responses and non-enzymatic were higher in DNF cats. Cats in the DNF group showed lower serum acute phase proteins in addition to a tendency toward a higher concentration of transferrin than in the DCF group. Fecal Escherichia coli and total coliform counts of cats fed DNF were higher than DCF. We conclude that the daily consumption of cats is adequate. This feed had greater digestibility of fiber and mineral matter, in addition to an improvement in antioxidant and immunological responses.

关键词： Alternative Feed Antioxidant Companion Animals Health

Effect of wire-arc directed energy deposition on the microstructural formation and age-hardening response of the Mg-9Al-1Zn(AZ91)alloy

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镁合金学报(英文) 2023年第6期11卷 1944-1958页

作者： Gloria Graf Petra Spoerk-Erdely Emad Maawad Michael Burtscher daniel Kiener Helmut Clemens Thomas klein Department of Materials Science Montanuniversität LeobenFranz Josef-Straße 188700 LeobenAustria Institute of Materials Physics Helmholtz-Zentrum HereonMax-Planck-Straße 121502 GeesthachtGermany LKR Light Metals Technologies Ranshofen Austrian Institute of TechnologyLamprechtshausener Straße 615282 RanshofenAustria Institute of Materials Science Joining and FormingGraz University of TechnologyKopernikusgasse 24/I8010 GrazAustria

In recent years,wire-arc directed energy deposition(wa DED),which is also commonly known as wire-arc additive manufacturing(WAAM),has emerged as a promising new fabrication technique for magnesium *** major reason for this is the possibility of producing parts with a complex geometry as well as a fine-grained *** the process has been shown to be applicable for Mg-Al-Zn alloys,there is still a lack of knowledge in terms of the influence of the WAAM process on the age-hardening ***,this study deals with the aging response of a WAAM AZ91 *** order to fully understand the mechanisms during aging,first,the as-built condition was analyzed by means of high-energy X-ray diffraction(HEXRD)and scanning electron *** investigations revealed a finegrained,equiaxed microstructure with adjacent areas of alternating Al ***,the difference between single-and double-step aging as well as conventional and direct aging was studied on the as-built WAAM AZ91 alloy for the first *** aging response during the various heat treatments was monitored via in situ HEXRD *** electron microscopy and hardness studies were *** results showed that the application of a double-step aging heat treatment at 325℃with pre-aging at 250℃slightly improves the mechanical properties when compared to the single-step heat treatment at 325℃.However,the hardness decreases considerably after the pre-aging ***,aging at lower temperatures is preferable within the investigated temperature range of 250-325℃.Moreover,no significant difference between the conventionally aged and directly aged samples was ***,the specimens showed enhanced precipitation kinetics during aging as compared to cast *** could be attributed to a higher amount of nucleation sites and the particular temperature profile of the solution heat treatment.

关键词： Wire-arc directed energy deposition Additive manufacturing High-energy X-ray diffraction Synchrotron Mg-Al-Zn alloys Age-hardening

Tribological behaviour of sintered iron based self-lubricating composites

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Friction 2017年第3期5卷 285-307页

作者： Jose daniel Biasoli DE MELLO Cristiano BINDER Gisele HAMMES Roberto BINDER Aloisio Nelmo klein Laboratorio de Materiais(LabMat) Universidade Federal de Santa Catarina Florianópolis 88.040-900 SC BrazilLaboratorio de Tribologia e Materiais Universidade Federal de Uberl(a)ndia Uberl(a)ndia 38.400-902 MG Brazil Laboratorio de Materiais(LabMat) Universidade Federal de Santa Catarina Florianópolis 88.040-900 SC Brazil Whirlpool Embraco Unit Joinville 89.219-900 SC Brazil

This work is a review of previous works,presenting and discussing the most important results obtained by an ongoing research program towards the development of innovative,low-cost,self-lubricating composites with a low friction coefficient and high mechanical strength and wear *** emphasis is given to uniaxial die pressing of solid lubricant particles mixed with matrix powders and to metal injection moulding associated with in situ generation of solid lubricant ***,a microstructural model/processing route (powder injection moulding followed by plasma-assisted debinding and sintering) produced a homogeneous dispersion of in situ generated solid lubricant *** nodules of graphite with diameter smaller than 20 μm were formed,constituting a nanostructured stacking of graphite foils with nanometric *** Raman analysis indicated that the graphite nodules were composed of turbostratic 2D graphite having highly misaligned graphene planes separated by large interlamellae *** interplanar distance between the graphene foils and misalignment of these foils were confirmed by transmission electron microscopy and were,probably,the origin of the outstandingly low dry friction coefficient (0.04).The effect of sintering temperature,precursor content,metallic matrix composition and surface finish is also ***,the influence of a double-pressing/double-sintering (DPDS) technique on the tribological performance of self-lubricating uniaxially die-pressed hBN + graphite-Fe-Si-C-Mo composite is also ***,the tribological behaviour of die-pressed Fe-Si-C matrix composites containing 5,7.5 and 10 wt％ solid lubricants (hBN and graphite) added during the mixing step is analysed in terms of mechanical properties and wear ***,the synergy between solid lubricant particles dispersed in a metallic matrix and fluid lubricants in a cooperative mixed lubrication regime is presented.

关键词： tribological behaviour powder metallurgy iron based self-lubricating composites turbostratic graphite

Exploring the limits of complexity: A survey of empirical studies on graph visualisation

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Visual Informatics 2018年第4期2卷 264-282页

作者： Vahan Yoghourdjian daniel Archambault Stephan Diehl Tim Dwyer Karsten klein Helen C.Purchase Hsiang-Yun Wu Monash University Australia Swansea University United Kingdom University of Trier Germany University of Konstanz Germany University of Glasgow United Kingdom University of TU Wien Austria

For decades,researchers in information visualisation and graph drawing have focused on developing techniques for the layout and display of very large and complex *** involving human participants have also explored the readability of different styles of layout and representations for such *** both bodies of literature,networks are frequently referred to as being‘large’or‘complex’,yet these terms are *** a human-centred,experiment point-of-view,what constitutes‘large’(for example)depends on several factors,such as data complexity,visual complexity,and the technology *** this paper,we survey the literature on human-centred experiments to understand how,in practice,different features and characteristics of node–link diagrams affect visual complexity.

关键词： Graph visualisation Network visualisation node-link diagrams Cognitive scalability Evaluations Empirical studies

Effect of temperature and atmosphere on the tribological behavior of a polyether ether ketone composite

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Friction 2015年第4期3卷 259-265页

作者： Felipe Darabas RZATKI Diego Vinicius Dalevedo BARBOZA Renan Muller SCHROEDER Guilherme Mariz de Oliveira BARRA Cristiano BINDER Aloisio Nelmo klein Josédaniel Biasoli DE MELLO Federal University of Santa Catarina-UFSC Mechanical Engineering DepartmentMaterials LaboratoryFlorianópolisSCBrazil Whirlpool/Embraco JoinvilleSCBrazil

Polyether ether ketone(PEEK)is a high-performance thermoplastic,which is often selected for high-temperature tribological applications under chemically aggressive *** present work investigates the tribological behavior of a high-performance PEEK composite under conditions that are often found inside hermetic ***,an AMTI tribometer equipped with a hermetic chamber and a heating system was used to conduct sliding tests of PEEK cylinders on AISI 304 stainless steel polished discs(S_(q)<10 nm)with reciprocating movement and a normal force of 175 *** tribological behavior of the PEEK/AISI 304 stainless steel system was investigated as a function of ambient temperature(30℃ and 80℃)and atmosphere(atmospheric air and tetrafluoroethane).Wear and surface roughness analyses were performed with white light interferometry and optical *** spectroscopy was used to investigate transfer films on the counter body *** was observed to have a strong influence on the tribological behavior of the samples tested under atmospheric air,with a 25%decrease in the friction coefficient associated with a 100%increase in the wear ***,the friction measured from the samples tested under a tetrafluoroethane atmosphere showed no significant temperature dependence.

关键词： solid lubricant thermoplastics environment temperature

Few-Shot Learning Enables Population-Scale Analysis of Leaf Traits in Populus trichocarpa

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Plant Phenomics 2023年第3期5卷 581-597页

作者： John Lagergren Mirko Pavicic Hari B.Chhetri Larry M.York Doug Hyatt David Kainer Erica M.Rutter Kevin Flores Jack Bailey-Bale Marie klein Gail Taylor daniel Jacobson Jared Streich Biosciences Division Oak Ridge National LaboratoryOak RidgeTNUSA Department of Applied Mathematics University of CaliforniaMercedCAUSA Department of Mathematics North Carolina State UniversityRaleighNCUSA Department of Plant Sciences University of CaliforniaDavisCAUSA

Plant phenotyping is typically a time-consuming and expensive endeavor,requiring large groups of researchers to meticulously measure biologically relevant plant traits,and is the main bottleneck in understanding plant adaptation and the genetic architecture underlying complex traits at population *** this work,we address these challenges by leveraging few-shot learning with convolutional neural networks to segment the leaf body and visible venation of 2,906 Populus trichocarpa leaf images obtained in the *** contrast to previous methods,our approach(a)does not require experimental or image preprocessing,(b)uses the raw RGB images at full resolution,and(c)requires very few samples for training(e.g.,just 8 images for vein segmentation).Traits relating to leaf morphology and vein topology are extracted from the resulting segmentations using traditional open-source image-processing tools,validated using real-world physical measurements,and used to conduct a genome-wide association study to identify genes controlling the *** this way,the current work is designed to provide the plant phenotyping community with(a)methods for fast and accurate image-based feature extraction that require minimal training data and(b)a new population-scale dataset,including 68 different leaf phenotypes,for domain scientists and machine learning *** of the few-shot learning code,data,and results are made publicly available.

关键词： networks neural image