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journal of Materials Science & Technology 2019年第12期35卷 2906-2918页

作者： evan j.pineda Marek Fassin Stefanie Reese jaan-Willem Simon NASA Glenn Research Center 21000 Brookpark RoadMS 49/7ClevelandOH 44135United States Institute for Applied Mechanics RWTH Aachen UniversityMies-van-der-Rohe-Str.152074 AachenGermany

Three different multiscale models, based on the method of cells(generalized and high fidelity) micromechanics models were developed and used to predict the elastic properties of C/C-SiC composites. In particular, the following multiscale modeling strategies were employed: Concurrent modeling of all phases using the generalized method of cells, synergistic(two-way coupling in space) multiscale modeling with the generalized method of cells, and hierarchical(one-way coupling in space) multiscale modeling with the high fidelity generalized method of cells. The three models are validated against data from a hierarchical multiscale finite element model in the literature for a repeating unit cell of C/***, the multiscale models are used in conjunction with classical lamination theory to predict the stiffness of C/C-SiC plates manufactured via a wet filament winding and liquid silicon infiltration process recently developed by the German Aerospace Institute. Finally, un-reacted Si(or free Si) and porosity in the C matrix are included in the multiscale model, and the effect of these new phases on the stiffness and local stresses are considered.

关键词： Multiscale modeling C/C-SiC Ceramic matrix composites

Weave geometry generation avoiding interferences for mesoscale RVEs

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journal of Materials Science & Technology 2019年第12期35卷 2869-2882页

作者： Daniel Höwer Shengkai Yu Trenton M.Ricks Brett A.Bednarcyk evan j.pineda Bertram Stier Stefanie Reese jaan-Willem Simon Institute of Applied Mechanics RWTH Aachen University52074 AachenGermany NASA Glenn Research Center ClevelandOH 44135USA Collier Research and Development Corporation Newport NewsVA 23606USA

An algorithm which allows the generation of representative volume elements(RVEs) for complex woven and warp-interlaced fiber-reinforced composite topologies while avoiding unphysical tow intersections is presented. This is achieved by extending an existing RVE generation strategy in two significant ways:(1) the local cross section shape of the tow is adjusted depending on the local tow curvature in a way that preserves the cross sectional area of the tow, and(2) the elementary crimp interval is separated into a planar and a transition region. The modifications facilitate the generation of a wide range of elaborate textile topologies without tow intersections, which are present without the proposed modifications unless complex tow to tow contact models are introduced. The mechanical properties of plain weaves were predicted based on the topology generated with the proposed algorithm as well as based on RVEs which were constructed based on actual micrographs, i.e. a "digital twin" of the actual microstructure. A comparison of the predicted mechanical properties based on finite element and Multiscale Generalized Method of Cells techniques shows close agreement. However, some differences exist with respect to experimentally determined material parameters due to the finite dimensions of the specimens. Lastly,mechanical properties of multilayered weaves are predicted with the finite element method. The considered material systems are carbon fiber in epoxy matrix as well as C/C-SiC. However, the procedure is applicable to a wide range of material systems.

关键词： RVE generation Multiscale analysis Composites

Predicting the synthesizability of crystalline inorganic materials from the data of known material compositions

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npj Computational Materials 2023年第1期9卷 733-743页

作者： evan R.Antoniuk Gowoon Cheon George Wang Daniel Bernstein William Cai evan j.Reed Materials Science Division Physical and Life Sciences DirectorateLawrence Livermore National LaboratoryLivermoreCAUSA Department of Chemistry Stanford UniversityStanfordCAUSA Department of Applied Physics Stanford UniversityStanfordCAUSA Google Research Mountain ViewCAUSA Department of Physics Stanford UniversityStanfordCAUSA Department of Mathematics Stanford UniversityStanfordCAUSA Department of Computer Science Stanford UniversityStanfordCAUSA Department of Materials Science and Engineering Stanford UniversityStanfordCAUSA

Reliably identifying synthesizable inorganic crystalline materials is an unsolved challenge required for realizing autonomous materials *** this work,we develop a deep learning synthesizability model(SynthNN)that leverages the entire space of synthesized inorganic chemical *** reformulating material discovery as a synthesizability classification task,SynthNN identifies synthesizable materials with 7×higher precision than with DFT-calculated formation *** a head-to-head material discovery comparison against 20 expert material scientists,SynthNN outperforms all experts,achieves 1.5×higher precision and completes the task five orders of magnitude faster than the best human ***,without any prior chemical knowledge,our experiments indicate that SynthNN learns the chemical principles of charge-balancing,chemical family relationships and ionicity,and utilizes these principles to generate synthesizability *** development of SynthNN will allow for synthesizability constraints to be seamlessly integrated into computational material screening workflows to increase their reliability for identifying synthetically accessible materials.

关键词： inorganic crystalline utilize

Beyond first-line chemotherapy for advanced pancreatic cancer:An expanding array of therapeutic options?

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World journal of Gastroenterology 2014年第9期20卷 2224-2236页

作者： evan j Walker Andrew H Ko University of California Helen Diller Family Comprehensive Cancer Center San Francisco CA 94115 United States

While an increasing number of therapeutic options are now available for the first-line treatment of locally advanced or metastatic pancreatic cancer,the optimal choice for treatment in the second-line setting and beyond is less well defined.A variety of cytotoxic agents,either alone or in combination,have been evaluated,although primarily in the context of small single-arm or retrospective *** regimens have been associated with median progression-free survival rates in the range of 2-4 mo and overall survival rates between 4-8mo,highlighting the very poor prognosis of patients who are candidates for such *** therapies studied in this chemotherapy-refractory setting,meanwhile,have produced even worse efficacy *** the current article,we review the clinical evidence for treatment of refractory disease,primarily in patients who have progressed on front-line gemcitabine-based *** the process,we highlight the limitations of the available data to date as well as some of the challenges in designing appropriate clinical trials in this salvage setting,including how to select an appropriate control arm given the absence of a wellestablished reference standard,and the importance of incorporating predictive biomarkers and quality of life measures whenever possible into study design.

关键词： Pancreatic cancer Refractory Second-line chemotherapy Gemcitabine

Theoretical potential for low energy consumption phase change memory utilizing electrostatically-induced structural phase transitions in 2D materials

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npj Computational Materials 2018年第1期4卷 653-661页

作者： Daniel A.Rehn Yao Li Eric Pop evan j.Reed Department of Mechanical Engineering Stanford UniversityStanfordCA 94305USA Department of Applied Physics Stanford UniversityStanfordCA 94305USA Department of Electrical Engineering Stanford UniversityStanfordCA 94305USA Department of Materials Science and Engineering Stanford UniversityStanfordCA 94305USA

Structural phase-change materials are of great importance for applications in information storage *** driven structural phase transitions are employed in phase-change memory to achieve lower programming voltages and potentially lower energy consumption than mainstream nonvolatile memory ***,the waste heat generated by such thermal mechanisms is often not optimized,and could present a limiting factor to widespread *** potential for electrostatically driven structural phase transitions has recently been predicted and subsequently reported in some two-dimensional materials,providing an athermal mechanism to dynamically control properties of these materials in a nonvolatile fashion while achieving potentially lower energy *** this work,we employ DFT-based calculations to make theoretical comparisons of the energy required to drive electrostatically-induced and thermally-induced phase *** theoretical limits in monolayer MoTe2 and thin films of Ge_(2)Sb_(2)Te_(5),we find that the energy consumption per unit volume of the electrostatically driven phase transition in monolayer MoTe2 at room temperature is 9% of the adiabatic lower limit of the thermally driven phase transition in Ge_(2)Sb_(2)Te_(5).Furthermore,experimentally reported phase change energy consumption of Ge_(2)Sb_(2)Te_(5) is 100–10,000 times larger than the adiabatic lower limit due to waste heat flow out of the material,leaving the possibility for energy consumption in monolayer MoTe2-based devices to be orders of magnitude smaller than Ge_(2)Sb_(2)Te_(5)-based devices.

关键词： transitions phase structural

From Slater to Mott physics by epitaxially engineering electronic correlations in oxide interfaces

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npj Computational Materials 2021年第1期7卷 846-851页

作者： Carla Lupo evan Sheridan Edoardo Fertitta David Dubbink Chris j.Pickard Cedric Weber Theory and Simulation of Condensed Matter King’s College LondonLondonUK Happy Electron Ltd LondonUK Department of Materials Science and Metallurgy University of CambridgeCambridgeUK Advanced Institute for Materials Research Tohoku UniversitySendaiJapan

Using spin-assisted ab initio random structure searches,we explore an exhaustive quantum phase diagram of archetypal interfaced Mott insulators,***-iron and lanthanum-titanium *** particular,we report that the charge transfer induced by the interfacial electronic reconstruction stabilises a high-spin ferrous Fe2+*** provide a pathway to control the strength of correlation in this electronic state by tuning the epitaxial strain,yielding a manifold of quantum electronic phases,***-Hubbard,charge transfer and Slater insulating ***,we report that the electronic correlations are closely related to the structural oxygen octahedral rotations,whose control is able to stabilise the low-spin state of Fe2+at low pressure previously observed only under the extreme high pressure conditions in the Earth’s lower ***,we provide avenues for magnetic switching via THz radiations which have crucial implications for next generation of spintronics technologies.

关键词： Slater lanthanum quantum

A Group of Cu(Zr)-based BMGs with Critical Diameter in the Range of 12 to 18 mm

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journal of Materials Science & Technology 2008年第2期24卷 149-152页

作者： Yong SHEN evan MA jian XU Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering The Johns Hopkins University Baltimore Maryland 21218 USA

A group of Cu（Zr）-based bulk metallic glasses （BMGs） with critical diameter （De） in the 12 to 18 mm range have been obtained using copper mould casting. In the Cu-Zr-Y-Al quaternary system, a new record of Dc=14 mm was established for Cu-based compositions, and 16 mm for compositions based on equi-atomic CuZr. Additional partial substitution of Hf for Zr further elevated the Dc to 18 mm at Cu42Zr43Hf1.5Y3.5Al10.

关键词： Bulk metallic glasses Glass-forming ability Copper Zirconium

Leaching of lanthanide and yttrium from a Central Appalachian coal and the ashes obtained at 550-950℃

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journal of Rare Earths 2022年第5期40卷 807-814,I0005页

作者： Ronghong Lin Yee Soong Bret H.Howard Murphy j.Keller Elliot A.Roth Ping Wang evan j.Granite U.S.Department of Energy National Energy Technology Laboratory626 Cochrans Mill RoadP.O.Box 10940PittsburghPA15236United States Keylogic Systems.Pittsburgh PA15236United States

In this work,we investigated leaching of lanthanide and yttrium(REY) from a Central Appalachian coal and its ashes obtained at 550-950℃ with the main purpose of understanding the impact of ashing temperature on REY leachability in water,ammonium sulfate,and hydrochloric *** is found that the coal contains a negligible amount of water-soluble REY,less than 1% ion-exchangeable REY,and about 28% of HCl-soluble *** leads to dramatic changes in REY leachability in both ammonium sulfate and hydrochloric acid solutions,which is believed to be related to transformation and redistribution of organically-associated REY in coal during the ashing *** temperature significantly affects REY leaching from coal ashes;higher ashing temperature results in lower REY leachability in both *** minerals may play a significant role in changing the leachability of REY after *** addition,the results also suggest that the organic matter in the coal is relatively enriched in heavy REY.

关键词： Acid leaching Cation exchange Coal Coal ash Rare earth elements Yttrium

Development of a multivariate empirical model for predicting weak rock mass modulus

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International journal of Mining Science and Technology 2015年第4期25卷 545-552页

作者： Kallu Raj R. Keffeler evan R. Watters Robert j. Agharazi Alireza Department of Mining Engineering University of Nevada RESPEC Consulting and Services University of Nevada Itasca Houston Inc.

Estimating weak rock mass modulus has historically proven difficult although this mechanical property is an important input to many types of geotechnical analyses. An empirical database of weak rock mass modulus with associated detailed geotechnical parameters was assembled from plate loading tests per- formed at underground mines in Nevada, the Bakhtiary Dam project, and Portugues Dam project. The database was used to assess the accuracy of published single-variate models and to develop a multivari- ate model for predicting in-situ weak rock mass modulus when limited geoteehnical data are available. Only two of the published models were adequate for predicting modulus of weak rock masses over lim- ited ranges of alteration intensities, and none of the models provided good estimates of modulus over a range of geotechnical properties. In light of this shortcoming, a multivariate model was developed from the weak rock mass modulus dataset, and the new model is exponential in form and has the following independent variables：（1） average block size or joint spacing, （2） field estimated rock strength, （3） dis- continuity roughness, and （4） discontinuity infilling hardness. The multivariate model provided better estimates of modulus for both hard-blocky rock masses and intensely-altered rock masses.

关键词： In-situ modulus Weak rock mass Preliminary design Elastic deformation

A Hunter-Gatherer Exercise Prescription to Optimize Health and Well-Being in the Modern World

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journal of Science in Sport and Exercise 2021年第2期3卷 147-157页

作者： evan L.O’Keefe Carl j.Lavie Ochsner Clinical School The University of Queensland School of MedicineNew OrleansLAUSA Department of Cardiovascular Diseases John Ochsner Heart and Vascular Institute1514 Jefferson HighwayNew OrleansLA 70121-2483USA

There has been considerable innovation and advancement in the field of exercise and physical activity (PA).In regards to the battle against chronic non-communicable disease,however,we believe the model of PA that would prove most salu-tary is one closely mimicking that of our hunter-gatherer *** the purpose of longevity,the human body and our genetic makeup have been evolutionarily adapted to respond best to moderate amounts of high-intensity interval training,in conjunction with high amounts of low intensity ***,to optimize resiliency and cardiorespiratory fitness,a hunter-gatherer fitness regimen must include cross training targeted at flexibility,balance and *** not com-monly understood,the health benefits from exercise comprise a reverse *** endurance athletes residing on the furthest reaches of the PA spectrum appear to lose a substantial portion of the exercise-related longevity and cardiovascular benefits due to cardiac overuse ***,there is an emerging body of evidence suggesting leisure time exercise done with peers in a natural environment is significantly superior to that training done in *** idea of the "power of play" lends support to the ancestral model of PA whereby humans are evolutionary adapted to be highly social,outdoor creatures capable of a diverse range of PA at varying intensities.

关键词： Hunter-gatherer Cardiovascular disease Physical activity Exercise