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Selective Laser Melting under variable Ambient Pressure: A Mesoscopic Model and Transport Phenomena

Engineering 2021年第8期7卷 1157-1164页

作者： Renzhi Hu Manlelan Luo Anguo Huang Jiamin Wu Qingsong Wei Shifeng Wen Lichao Zhang Yusheng Shi dmitry Trushnikov v.Ya.Belenkiy i.Yu.Letyagin K.P.karunakaran Shengyong Pang State Key Laboratory of Materials Processing and Die and Mould Technology Huazhong University of Science and TechnologyWuhan 430074China Department of Welding Production Metrologyand Technology of MaterialsPerm National Research Polytechnic UniversityPerm 614990Russia Department of Mechanical Engineering Indian Institute of Technology BombayMumbai 400076India

Recent reports on the selective laser melting(SLM)process under a vacuum or low ambient pressure have shown fewer defects and better surface quality of the as-printed *** the physical process of SLM in a vacuum has been investigated by high-speed imaging,the underlying mechanisms governing the heat transfer and molten flow are still not well ***,we first developed a mesoscopic model of SLM under variable ambient pressure based on our recent laser-welding *** simulated the transport phenomena of SLM 316L stainless steel powders under atmospheric and 100 Pa ambient *** typical process parameters(laser power:200W;scanning speed:2m∙s^(-1);powder diameter:27 lm),the average surface temperature of the cavity approached 2800 K under atmospheric pressure,while it came close to 2300 K under 100 Pa *** vigorous fluid flow(average speed:4m∙s^(-1))was observed under 100 Pa ambient pressure,because the pressure difference between the evaporation-induced surface pressure and the ambient pressure was relatively larger and drives the flow under lower *** was also shown that there are periodical ripple flows(period:14ls)affecting the surface roughness of the as-printed ***,the molten flow was shown to be laminar because the Reynolds number is less than 400 and is far below the critical value of turbulence;thus,the viscous dissipation is *** was demonstrated that under a vacuum or lower ambient pressure,the ripple flow can be dissipated more easily by the viscous effect because the trajectory length of the ripple is longer;thus,the surface quality of the tracks is *** summarize,our model elucidates the physical mechanisms of the interesting transport phenomena that have been observed in independent experimental studies of the SLM process under variable ambient pressure,which could be a powerful tool for optimizing the SLM process in the future.

关键词： Selective laser melting Mesoscopic model Ambient pressure Transport phenomena

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Operating limits and features of direct air capture on K_(2)CO_(3)/ZrO_(2) composite sorbent

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Chinese Journal of Chemical Engineering 2022年第6期35卷 11-20页

作者： vladimir S.Derevschikov Janna v.veselovskaya Anton S.Shalygin dmitry A.Yatsenko Andrey Z.Sheshkovas Oleg N.Martyanov Boreskov institute of Catalysis SB RAS Akademika Lavrentieva Av.5630090 NovosibirskRussia Novosibirsk State University Pirogova Str.1630090 NovosibirskRussia

Potassium carbonate-based sorbents are prospective materials for direct air capture(DAC).in the present study,we examined and revealed the influence of the temperature swing adsorption(TSA)cycle conditions on the CO_(2) sorption properties of a novel aerogel-based K_(2)CO_(3)/ZrO_(2) sorbent in a DAC *** was shown that the humidity and temperature drastically affect the sorption dynamic and sorption capacity of the *** a temperature at the sorption stage was 29℃ and a water vapor pressure P_(H2O) in the feed air was 5.2 mbar(1 bar=105 Pa),the composite material demonstrated a stable CO_(2) sorption capacity of 3.4%(mass).An increase in sorption temperature leads to a continuous decrease in the CO_(2) absorption capacity reaching a value of 0.7%(mass)at T=80℃.The material showed the retention of a stable CO_(2) sorption capacity for many cycles at each temperature in the *** PH2O in the inlet air from 5.2 to 6.8 mbar leads to instability of CO_(2) sorption capacity which decreases in the course of 3 consecutive TSA cycles from 1.7%to 0.8%(mass)at T=29℃.A further increase in air humidity only facilitates the deterioration of the CO_(2) sorption capacity of the material.A possible explanation for this phenomenon could be the filling of the porous system of the sorbent with solid reaction products and an aqueous solution of potassium salts,which leads to a significant slowdown in the CO_(2) diffusion in the composite sorbent *** investigate the regeneration step of the TSA cycle in situ,the macro ATRFTiR(attenuated total reflection Fourier-transform infrared)spectroscopic imaging was applied for the first *** was shown that the migration of carbonate-containing species over the surface of sorbent occurs during the thermal regeneration stage of the TSA *** movement of the active component in the porous matrix of the sorbent can affect the sorption characteristics of the composite *** revealed features make it possible

关键词： Zirconia aerogel Potassium carbonate Carbon dioxide Direct air capture Fourier-transform infrared spectroscopic imaging

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Phylogenetic relationship and variation of alarm call traits of populations of red-cheeked ground squirrels(Spermophilus erythrogenys sensu lato)suggest taxonomic delineation

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integrative Zoology 2019年第4期14卷 341-353页

作者： vera A.MATROSOvA Anastasia D.ivANOvA Elena v.vOLODiNA ilya A.vOLODiN dmitry Yu.ALEXANDROv Olga v.SiBiRYAKOvA Oleg A.ERMAKOv Engelhardt institute of Molecular Biology RASMoscowRussia Lomonosov Moscow State University MoscowRussia Moscow Zoo MoscowRussia Severtsov institute of Ecology and Evolution RASMoscowRussia Department of Zoology and Ecology Penza State UniversityPenzaRussia

Distribution area and taxonomic borders within the species complex Spermophilus erythrogenys sensu lato remain *** evidence suggests that red-cheeked ground squirrels of Southeast kazakhstan are remarkably different in terms of the acoustic structure of their alarm calls from the red-cheeked ground squirrels of the Kurgan region in *** this study,we analyzed the differences in the acoustic structure of the alarm call and mitochondrial DNA(complete control region,1005-1006 bp and complete cytochrome b gene,1140 bp)in 3 populations of red-cheeked ground squirrels(Tara,Altyn-Emel and Balkhash),all located within areas isolated by geographical barriers in Southeast *** found that the alarm call variables were similar between the 3 study populations and differed by the maximum fundamental frequency(8.46±0.75 kHz)from the values(5.62±0.06 kHz)reported for the red-cheeked ground squirrels from the Kurgan region of Rus*** in mtDNA control region was only 3%and variation in cytochrome b gene was only 2.5%.Phylogenetic trees based on cytochrome b gene polymorphism of 44 individuals from the study area and adjacent territories indicated 3 clades with high(98-100%)bootstrap support:“intermedius,”“brevicauda”and“iliensis”).We conclude that the 3 study populations in Southeast kazakhstan belong to the clade intermedius and suggest a taxonomical revision of the species complex Spermophilus erythrogenys sensu lato,including analyses of nuclear DNA and alarm calls for populations of the brevicauda and iliensis clades.

关键词： alarm call control region cytochrome b mitochondrial DNA vocal communication

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Clostridioides difficile infection in patients with nonalcoholic fatty liver disease-current status

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World Journal of Hepatology 2023年第2期15卷 208-215页

作者： Yana v Kiseleva Roman v Maslennikov Aida N Gadzhiakhmedova Tatyana S Zharikova dmitry v ka.i.in Yury O Zharikov international School“Medicine of the Future” I.M.Sechenov First Moscow State Medical University(Sechenov University)Moscow 119991Russia Department of internal Medicine Gastroenterology and HepatologyI.M.Sechenov First Moscow State Medical University(Sechenov University)Moscow 119435Russia Department of internal Medicine Сonsultative and Diagnostic Center No.2Moscow City Health DepartmentMoscow 107564Russia Department of Human Anatomy and Histology I.M.Sechenov First Moscow State Medical University(Sechenov University)Moscow 125009Russia Department of Pathology A.V.Vishnevsky National Medical Research Center of SurgeryMoscow 115093Russia

Nonalcoholic fatty liver disease(NAFLD)is the most common chronic liver disease,leading to fibrosis,cirrhosis and hepatocellular carcinoma and also associated with increased cardiovascular disease *** pathogenesis of NAFLD is not fully understood,although NAFLD is thought to be a hepatic form of metabolic *** is an increasing understanding of the role of microbiota disturbances in NAFLD pathogenesis,and as with many other conditions affecting the microbiota,NAFLD may be a novel risk factor for Clostridioides difficile(***)colonization(CDC)and *** infection(CDi).CDi is an emerging nosocomial disease,and community-acquired cases of infection are growing,probably due to an increase in CDC *** association of NAFLD with CDi has been shown in only 4 studies to date,three of which included less than 1000 patients,although the frequency of NAFLD in these studies was observed in almost 20%of the total patient *** data revealed that NAFLD is a risk factor for CDi development and,moreover,is a risk factor for intestinal complications of *** studies are needed to investigate this association and move forward CDC and CDi screening efforts for this group of patients.

关键词： Nonalcoholic fatty liver disease Clostridioides difficile Clostridioides difficile colonization Clostridioides difficile infection Minireview

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Electrolyte materials for protonic ceramic electrochemical cells:Main limitations and potential solutions

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Materials Reports(Energy) 2022年第4期2卷 19-35页

作者： Anna v.kasyanova inna A.Zvonareva Natalia A.Tarasova Lei Bi dmitry A.Medvedev Zongping Shao Laboratory of Electrochemical Devices Based on Solid Oxide Proton Electrolytes Institute of High Temperature Electrochemistry620990YekaterinburgRussia Hydrogen Energy Laboratory Ural Federal University620002YekaterinburgRussia School of Resource and Environment and Safety Engineering University of South ChinaHengyangHunan421001China State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing210009China WA School of Mines:Minerals Energy and Chemical Engineering(WASM-MECE)Curtin UniversityPerthWA6845Australia

Solid oxide fuel cells(SOFCs)and electrolysis cells(SOECs)are promising energy conversion devices,on whose basis green hydrogen energy technologies can be developed to support the transition to a carbon-free *** compared with oxygen-conducting cells,the operational temperatures of protonic ceramic fuel cells(PCFCs)and electrolysis cells(PCECs)can be reduced by several hundreds of degrees(down to low-and intermediatetemperature ranges of 400–700C)while maintaining high performance and *** is due to the distinctive characteristics of charge carriers for proton-conducting ***,despite achieving outstanding lab-scale performance,the prospects for industrial scaling of PCFCs and PCECs remain hazy,at least in the near future,in contrast to commercially available SOFCs and *** this review,we reveal the reasons for the delayed technological development,which need to be addressed in order to transfer fundamental findings into industrial *** solutions to the identified problems are also highlighted.

关键词： Protonic ceramic fuel cells(PCFCs) Protonic ceramic electrolysis cells(PCECs) Proton transport Electrochemistry Hydrogen energy

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新疆植物区系新资料(英文)

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植物分类学报 2006年第5期44卷 598-603页

作者： dmitry A. GERMAN Alexander i. SHMAKOv 张宪春陈文俐 Sergey v. SMiRNOv 谢磊 Rudolph v. kaMELiN 王健 Altai State University Barnaul 656049 Russia 系统与进化植物学国家重点实验室中国科学院植物研究所 Komarov Botanical institute St.-Petersburg 197376 Russia 新疆阿勒泰地区林业科学研究所

报道了采自新疆阿尔泰山地区的1个中国新记录属假糖芥属Rhammatophyllum O. E. Schulz, 6个中国新记录种——渐尖岩蕨Woodsia acuminata (Fomin) Sipl.、短命繁缕Stellaria alsinoides Boiss. & Buhse、假糖芥Rh. erysimoides (kar. & Kir.) Al-Shehbaz & O. Appel、克氏鹤虱Lappula krylovii Ovczinnikova, A. i. Pjak & A. L. Ebel、肝色柳穿鱼Linaria hepatica Bunge和佐氏新缬草valerianella szovitsiana Fisch. & Mey.。

关键词：假糖芥属渐尖岩蕨短命繁缕假糖芥克氏鹤虱肝色柳穿鱼佐氏新缬草新记录新疆中国

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Correct interpretation of Creep Rates: A Case Study of Cu

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Journal of Materials Science & Technology 2015年第11期31卷 1065-1068页

作者： W.Blum J.Dvoák P.Král P.Eisenlohr v.Sklenika institut für Werkstoffwissenschaften University of Erlangen-Nürnberg institute of Physics of Materials Academy of Sciences of the Czech Republic Department of Chemical Engineering and Materials Science Michigan State University

Traditionally the deformation resistance in creep is characterized by the minimum creep rate εmin and its sensitivity to stress （stress exponent n） and temperature （activation energy Q）. various values of constant n have been reported in the literature and interpreted in terms of specific mechanisms. The present case study of coarse-grained Cu at 573 K yields a stress exponent n = 9 for εmin. in tension and a relatively low activation energy. The evolution of the deformation resistance with strain at constant tensile creep load and comparison with creep in compression without fracture indicates that the tensile εmin. result from transition from uniform deformation to strain localization during fracture. This is confirmed by the results of creep in compression where fracture is suppressed. Both the tensile εmin, and the compressive creep rate at strains around 0.3 can be described using existing equations for quasi-stationary deformation containing the subgrain boundary misorientation θ as structure parameter. While in the latter case constant θ leads to monotonic increase of n with stress, the tensile nine-power-law results from variable θ, and has no simple meaning. The result of this case study means that uncritical interpretation of minimum tensile creep rates as stationary ones bears a high risk of systematic errors in the determination of creep parameters and identification of creep mechanisms.

关键词： Cu Creep Minimum creep rate Activation energy Stress exponent

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Thienopyrazine or Dithiadiazatrindene Containing Low Band Gap Conjugated Polymers for Polymer Solar Cells

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Chinese Journal of Polymer Science 2014年第7期32卷 844-853页

作者： Mukhamed L.Keshtov dmitry v.Marochkin Ying-ying Fu Zhi-yuan Xie 耿延候 vitaly S.Kochurov Alexei R.Khokhlov A.N.Nesmeyanov institute of Organoelement Compounds of Russian Academy of Sciences State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of Sciences Lomonosov Moscow State University Faculty of Physics 119991

Four new low-band-gap alternating copolymers （P-1, P-2, P-3 and P-4） based on electron-rich benzodithiophene and newly developed electron-deficient units, thienopyrazine or dithiadiazatrindene derivatives, were synthesized by Stille polycondensation. All polymers exhibit good solubility in common organic solvents and a broad absorption band in the visible to near-infrared regions. The film optical band gaps of the polymers are in the range of 1.28-2.07 ev and the highest occupied molecular orbital （HOMO） energy levels are in the range of-4.99 ev to -5.28 ev. Bulk heterojunction polymer solar cells （PSCs） of the polymers were fabricated with phenyl-C61-butyric acid methyl ester （PC61BM） as acceptor material, and a power conversion efficiency of 0.80% was realized with P-1 as donor material.

关键词： Low band gap Conjugated polymers Electron-deficient aromatics Polymer solar cells.

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Continuous wafer-scale graphene on cubic-SiC（O01）

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Nano Research 2013年第8期6卷 562-570页

作者： Alexander N. Chaika Olga v. Molodtsova Alexei A. Zakharov dmitry Marchenko Jaime Sanchez-Barrig Andrei varykhalov igor v. Shvets victor Yu. Aristov institute of Solid State Physics RAS Chemogolovka Moscow District 142432 Russia Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) School of Physics Trinity College Dublin 2 Ireland HASYLAB at DESY D-22607 Hamburg Germany MAX-lab Lund University Box 118 22100 Lund Sweden Helmholtz-Zentrum Berlin für Materialien und Energie D- 12489 Berlin Germany

The atomic and electronic structure of graphene synthesized on commercially available cubic-SiC（001）/Si（001） wafers have been studied by low energy electron microscopy （LEEM）, scanning tunneling microscopy （STM）, low energy electron diffraction （LEED）, and angle resolved photoelectron spectroscopy （ARPES）. LEEM and STM data prove the wafer-scale continuity and uniform thickness of the graphene overlayer on SiC（001）. LEEM, STM and ARPES studies reveal that the graphene overlayer on SiC（001） consists of only a few monolayers with physical properties of quasi-freestanding graphene. Atomically resolved STM and micro-LEED data show that the top graphene layer consists of nanometer-sized domains with four different lattice orientations connected through the 〈110〉-directed boundaries. ARPES studies reveal the typical electron spectrum of graphene with the Dirac points close to the Fermi level. Thus, the use of technologically relevant SiC（001）/Si（001） wafers for graphene fabrication repre-sents a realistic way of bridging the gap between the outstanding properties of graphene and their applications.

关键词： graphene cubic-SiC(001) STM ARPES LEEM LEED

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Generation of Runaway Electrons in Atmospheric Pressure Air Under 30-200 kv voltage Pulses of Rise Time 1.5 ns

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高电压技术 2013年第9期39卷 2112-2118页

作者： Sergey B. Alekseev Mikhail i. Lomaev dmitry v. Rybka v. F. Tarasenko SHAO Tao ZHANG Cheng YAN Ping institute of High Current Electronics SB RAS Tomsk 634055 Russia Tomsk Polytechnic University Tomsk 634050 Russia institute of Electrical Engineering Chinese Academy of Sciences Beijing 100190 China

A pulse generator with a voltage rise time of～1.5 ns and voltage amplitude variable from 30 kv to 200 kv was designed for generating runaway electron beams in atmospheric pressure air with different interelectrode *** influence of the voltage amplitude and gap length on the generation was *** the gas diode geometry under study,the gap voltage at which the generation of a runaway electron beam begins was *** the voltage pulse amplitude does not increase the beam current pulse width measured with a time resolution of～0.1 *** is shown that the escape of beam electrons to the downstream of the foil is sync in time with the voltage drop across the gap,and that the delay of beam current generation increases gradually from 1.1 ns to 2.6 ns as the voltage pulse amplitude across the gap decreases from～100 kv to 40 kv.

关键词：脉冲上升时间电压幅值逃逸电子大气压力纳秒空气间隙电压脉冲幅度

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