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Challenges and opportunities in the production of magnesium parts by directed energy deposition processes

Journal of Magnesium and Alloys 2024年第5期12卷 1663-1686页

作者： gürel cam Ali günen Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Mechanical Engineering31200 Iskenderun-HatayTurkey Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Metallurgy and Materials Engineering31200 Iskenderun-HatayTurkey

Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aerospace,automotive,and other transport ***,their widespread application is hindered by their low formability at room temperature due to limited slip *** Mg-alloys have low mechanical properties due to the presence of casting defects such as porosity and anisotropy in addition to the high *** casting methods benefit from established process optimization techniques for these problems,additive manufacturing methods are increasingly replacing casting methods in Mg alloys as they provide more precise control over the microstructure and allow specific grain orientations,potentially enabling easier optimization of anisotropy properties in certain *** metal additive manufacturing(MAM)technology also results in some manufacturing defects such as inhomogeneous microstructural evolution and porosity and additively manufactured Mg alloy parts exhibit lower properties than the wrought parts,they in general exhibit superior properties than the cast ***,MAM is a promising technique to produce Mg alloy *** energy deposition processes,particularly wire arc directed energy deposition(WA-DED),have emerged as an advantageous additive manufacturing(AM)technique for metallic materials including magnesium alloys,offering advantages such as high deposition rates,improved material efficiency,and reduced production costs compared to subtractive ***,the inherent challenges associated with magnesium,such as its high reactivity and susceptibility to oxidation,pose unique hurdles in the application of this *** review paper delves into the progress made in the application of DED technology to Mg-alloys,its challenges,and ***,the predominant imperfections,notably inhomo

关键词： Additive manufacturing DED processes Arc-DED Wire arc additive manufacturing(WAAM) 3-D printing High deposition rate

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Prevalence and outcomes of neonates with severe COVID-19:An observational study at Children’s Hospital 1 in Ho Chi Minh City,Vietnam

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Asian Pacific Journal of Tropical Medicine 2024年第9期17卷 392-399,I0001页

作者： Phung Nguyen The Nguyen Tran Thanh Thuc Nguyen Thanh Hung Ngo Ngoc Quang Minh Dang Quoc Duy Tran Minh Nhut Nguyen Hoang Dung Tran Nguyen Ai Nuong Dinh Nguyen cam Tu Department of Pediatrics University of Medicine and Pharmacy at Ho Chi Minh cityHo Chi Minh CityVietnam Children’s Hospital 1 Ho Chi Minh CityVietnam Pediatric Department School of MedicineVietnam National University Ho Chi Minh CityVietnam

Objective:To evaluate the impact of the severe COVID-19 pandemic on neonates and develop strategies to improve their ***:We conducted an observational cross-sectional study at Children's Hospital 1(CH1)from July 25,2021,to May 31,*** neonates who had fever or respiratory symptoms or were born from mothers with COVID-19 and had a positive RT-PCR SARS-CoV-2 result would be *** classified neonates with COVID-19 into 2 groups:mild/moderate and severe for *** between groups were analyzed using Fisher's exact test/Chi-square test for categorical variables and Student's t-test/Wilcoxon Rank Sum test for continuous ***:This study included 88 newborns who had positive RT-PCR SARS-CoV-2 *** severity COVID-19 rate among neonatal cases was found to be 13.6%(12/88),with a corresponding mortality rate of 1.1%(1/88).All severe cases showed lung abnormalities as evident on chest X-ray *** addition to respiratory symptoms,a higher incidence of gastrointestinal manifestations,such as vomiting and diarrhea,was observed in the severe group,indicating a compelling *** administration of anticoagulant and anti-inflammatory drugs in the study group resulted in a satisfactory outcome with no significant ***:The COVID-19 pandemic has had a substantial impact on the well-being of *** management of COVID-19 in this population presents significant challenges.

关键词： COVID-19 Neonate Anti-inflammatory Anticoagulant

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董事长“先生”又回来了?

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商业周刊（中文版） 2024年第7期 26-28页

作者： Zachary Fleming cam Baker Andre Tartar Raeedah Wahid 晴川(译) 不详

企业在董事长称谓上一直在稳步转向性别中立语言。但而今,对多元平等包容政策的批评又卷土重来。今年2月,芯片制造商Advanced Micro Devices Inc.(简称AMD)就在批准其CEO苏姿丰奖金方案的前一天,从公司章程中去掉了董事长英文头衔中带... 详细信息

企业在董事长称谓上一直在稳步转向性别中立语言。但而今,对多元平等包容政策的批评又卷土重来。今年2月,芯片制造商Advanced Micro Devices Inc.(简称AMD)就在批准其CEO苏姿丰奖金方案的前一天,从公司章程中去掉了董事长英文头衔中带有性别指向的部分(译注:董事长的英文为chairman,其中man指男性)。该公司在一份监管文件中称,这是“技术化、现代化、明晰化且顺应潮流的一系列变化”中的一部分。

关键词：芯片制造商明晰化公司章程董事长技术化

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A novel reusable anti-COVID-19 transparent face respirator with optimized airflow

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Bio-Design and Manufacturing 2021年第1期4卷 1-9页

作者： Hussain Alenezi Muhammet Emin cam Mohan Edirisinghe Department of Mechanical Engineering University College LondonTorrington PlaceLondon WC1E 7JEUK Department of Manufacturing Engineering College of Technological StudiesPAAET13092 Kuwait CityKuwait Center for Nanotechnology and Biomaterials Application and Research Marmara University34722 IstanbulTurkey

This novel face mask is designed to be a reusable respirator with a small and highly efficient disposable fabric *** material requirements are reduced by 75%compared to traditional designs and allow repeated cleaning or *** probability of virus particle inhalation is reduced using novel air filtration pathways,through square-waveform design to increase filter *** enters the mask from right and left side filters,while the area in front of the mouth is *** epoxy is used for a transparent frame,allowing lip-reading,and mask edges contain a silicone seal preventing bypass of the *** mask is manufactured using silicone molds,eliminating electricity requirements making it economical and viable in developing *** fluid dynamics numerical studies and Fluent ANSYS software were used to simulate airflow through the filter to optimize filter air path geometry and validate mask design with realistic human *** breathing cycle was represented as a transient function,and N95 filter specifications were selected as a porous *** novel design achieved 1.2×10^(−3) kg s^(−1),20%higher than human requirements,with air streamlines velocity indicating local high speed,forcing and trapping virus particles against filter walls through centrifugal forces.

关键词： COVID-19 Mask Prototype Flow Pressure Temperature

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Annual effective dose values from^137Cs activity concentrations in soils of Manisa,Turkey

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Nuclear Science and Techniques 2018年第7期29卷 164-170页

作者： Sermin cam Kaynar Department of Physics Faculty of Sciences and ArtsManisaCelal Bayar University45140 ManisaTurkey

In this study,the activity concentrations of the fallout radionuclide ^(137(Cs in 150 soil samples collected from 13 districts of Manisa Province were determined using a gamma ray spectrometer with a Na I(Tl) *** health risks to people resulting from external exposure were evaluated by estimating the outdoor absorbed gamma dose rate and annual effective dose rate(outdoor and indoor).The activity concentration of ^(137)Cs varied from 3.6 ± 2.0 to 124.1 ± 11.0 Bq kg^(-1),with an average value of43.3 Bq kg^(-1).The average values of the outdoor absorbed gamma dose rate and annual effective dose(outdoor plus indoor) were found to be 1.3 n gy h^(-1),and 8.0 μSv y^(-1),(6.38 + 1.59 μSv y^(-1)),*** results were compared with internationally recommended values.

关键词： 137Cs 平均价值有效剂量土壤样品土耳其 gamma 放射性核种健康风险

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Hard carbon derived from coconut shells,walnut shells,and corn silk biomass waste exhibiting high capacity for Na-ion batteries

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Journal of Energy Chemistry 2021年第7期30卷 207-218页

作者： Cristina Nita Biao Zhang Joseph Dentzer camélia Matei ghimbeu Universitéde Haute-Alsace Institut de Science des Matériaux de Mulhouse(IS2M)CNRS UMR 7361F-68100 MulhouseFrance Universitéde Strasbourg F-67081 StrasbourgFrance Center for Advanced Laser Technologies(CETAL) National Institute for LasersPlasma and Radiation PhysicsAtomistilor 409 bisRO-77125 MagureleRomania Department of Applied Physics The Hong Kong Polytechnic UniversityKowloonHong KongChina Réseau sur le Stockage Electrochimique de l’Energie(RS2E) CNRS FR345933 Rue Saint Leu80039 Amiens CedexFrance

In recent years,hard carbon materials have gained significant interest as anode materials for Na-ion *** waste is considered one of the most interesting,renewable,available,and cost-effective precursor to obtain hard carbon(HC);however,HC properties must be finely tuned to achieve performance comparable to those provided by Li-ion *** this work,three biomass wastes(coconut shells,walnut shells,and corn silk) were evaluated as potential precursors for HC preparation involving a pyrolysis process and subsequent acid washing to remove the inorganic *** obtained materials exhibited low and similar specific surface areas(g^(-1)), but they presented different structures and surface *** walnut shell HC possessed a lower amount of inorganic impurities and oxygen-based functional groups compared to the coconut shell and corn silk HCs,leading to higher initial coulombic efficiency(iCE).The structural organization was higher in the case of the walnut shell HC,while the corn silk HC revealed a heterogeneous structure combining both highly disordered carbon and localized graphitized *** HCs delivered high initial reversible capacities between 293 and 315 mAh g^(-1) at 50 mA g^(-1) current rate,which remained rather stable during long-term *** best capacity(293 mAh g^(-1) after 100 charge/discharge cycles) and highest capacity retention(93%) was achieved in walnut HCs in half-cells,which could be associated with its higher sp2 C content,better organized structure,and fewer *** "adsorption-insertion" Na storage mechanism is suggested based on several *** walnut HCs exhibited an attractive energy density of 279 Wh/kg when tested in full cells.

关键词： Biomass Pyrolysis Hard carbon Anode Na-ion batteries Energy storage

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Microstructure and mechanical properties of friction-stir welded St52 steel joints

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International Journal of Minerals,Metallurgy and Materials 2018年第12期25卷 1457-1464页

作者： Tevfik kucukomeroglu Semih M.Aktarer guven Ipekoglu gurel cam Department of Mechanical Engineering Karadeniz Technical UniversityTrabzon 61080Turkey Department of Automotive Technology Recep Tayyip Erdogan UniversityRize 53100Turkey Department of Mechanical Engineering Iskenderun Technical UniversityHatay 31200Turkey

The aim of this work is to investigate the mechanical properties and microstructures of friction-stir welded(FSWed) St52 structural steel joints. In this study, St52 steel plates with a thickness of 4 mm were butt-welded by friction-stir welding(FSW) using a tungsten carbide tool having a conical pin. The microstructure of the welded zone consists of equiaxed fine ferrite, grain boundary ferrite, Widmanstatten ferrite, and aggregates of ferrite + cementite. The microhardness measurements showed that the hardness of the welded zone was significantly higher than that of the base metal. The FSWed St52 joint exhibited a significant strength overmatching in the weld region and a strength performance similar to or slightly higher than that of the base plate.

关键词： friction-stir welding St52 steel microstructure mechanical properties

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Utilizing neural networks to supplant chemical kinetics tabulation through mass conservation and weighting of species depletion

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Energy and AI 2024年第2期16卷 101-110页

作者： Franz M.Rohrhofer Stefan Posch Clemens gößnitzer JoséM.garcía-Oliver Bernhard C.geiger Know-Center gmbH Sandgasse 36Graz8010StyriaAustria LEC gmbH Inffeldgasse 19Graz8010StyriaAustria Universitat Politècnica de València Camíde VeraValència46022ValènciaSpain

Artificial Neural Networks(ANNs)have emerged as a powerful tool in combustion simulations to replace memory-intensive tabulation of integrated chemical *** reaction mechanisms,however,present a challenge for standard ANN approaches as modeling multiple species typically suffers from inaccurate predictions on minor *** paper presents a novel ANN approach which can be applied on complex reaction mechanisms in tabular data form,and only involves training a single ANN for a complete reaction *** approach incorporates a network architecture that automatically conserves mass and employs a particular loss weighting based on species *** modifications are used to improve the overall ANN performance and individual prediction accuracies,especially for minor species mass *** validate its effectiveness,the approach is compared to standard ANNs in terms of performance and ANN *** distinct reaction mechanisms(H_(2),C_(7)H_(16),C_(12)H_(26),OME_(34))are used as a test cases,and results demonstrate that considerable improvements can be achieved by applying both modifications.

关键词： Neural network approach Chemical kinetics Flamelet tabulation Mass conservation Species loss weighting

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High incidence of nasopharyngeal cancer: similarity for 60% of mitochondrial DNA signatures between the Bidayuhs of Borneo and the Bai-yue of Southern China

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Chinese Journal of Cancer 2012年第9期31卷 455-456页

作者： Joseph Wee Tam cam Ha Susan Loong Chao-Nan Qian Department of Radiation Oncology National Cancer Centre Singapore Division of Clinical Trials&Epidemiological Sciences National Cancer Centre Singapore Duke-NUS graduate Medical School State Key Laboratory of Oncology in South China Sun Yat-sen University Cancer Center Van Andel Research Institute

Populations in Southern China (Bai-yue) and Borneo (Bidayuh) with high incidence of nasopharyngeal cancer (NPC) share similar mitochondrial DNA signatures, supporting the hypothesis that these two populations may share the same genetic predisposition for NPC, which may have first appeared in a common ancestral reference population before the sea levels rose after the last ice age.

关键词：线粒体DNA 中国南方相似性婆罗洲发病率鼻咽癌签名遗传易感性

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Determination of ^(210)Po and ^(210)Pb depositions in lichen and soil samples collected from K?prüba??-Manisa,Turkey

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Nuclear Science and Techniques 2018年第6期29卷 92-100页

作者： Sermin cam Kaynar Umit H. Kaynar Umran Hicsonmez Omer S. Sevinc Department of Physics Faculty of Sciences and Arts Manisa Celal Bayar University 45140 Manisa Turkey Science Education Faculty of Education Manisa Celal Bayar University 45900 Manisa Turkey Department of Chemistry Faculty of Sciences and ArtsManisa Celal Bayar University 45140 Manisa Turkey Primary School Science Teaching Duzce University81620 Manisa Turkey

üIn this study, we aimed to determine the accumulations of ^(210) Po and ^(210) Pb in soil and lichen samples in K? prü bas??. The K? prü bas?? district is home to the largest uranium deposits in Turkey. To date, there has been no study recorded in the literature related to ^(210) Po and ^(210) Pb depositions in lichens in K? prü bas??. Six different lichen species(Cladonia convoluta, Parmelina tiliacea, Physcia stellaris, Pleurosticta acetabulum, Xanthoparmelia conspersa, and Xanthoria parietina) as well as soil samples were collected from seven sampling locations around K? prü bas??. Lichens were used as biomonitors for ^(210) Po and ^(210) Pb deposition. The ^(210) Po and ^(210) Pb activity concentrations were measured in all the samples by alpha spectrometry. The activity concentrations in the lichen samples ranged from 64 to 577 Bq kg^(-1) with an average of 266 Bq kg^(-1) for ^(210) Po and from 78 to 565 Bq kg^(-1) with an average of 333 Bq kg^(-1) for ^(210) Pb. The activity ratios of ^(210) Po/ ^(210) Pb ranged from 0.80 to 1.99. In the lichen species,the mean ^(210) Po activity values varied from 154 Bq kg^(-1) in Pleurosticta acetabulum to 390 Bq kg^(-1) in Xanthoparmelia conspersa. The range of the mean ^(210) Pb activity was between 153 Bq kg^(-1) in Cladonia convoluta and 378 Bq kg^(-1) in Parmelina tiliacea. In the soil samples, ^(210) Po and ^(210) Pb activity concentrations were ranged from14 to 1268 Bq kg^(-1) and from 19 to 1113 Bq kg^(-1),respectively. While the values of ^(210) Po and ^(210) Pb measured in the lichen samples are comparable with those of the literature, the results of ^(210) Po and ^(210) Pb in the soil taken from the uranium mine are higher than the results of the literature studies.

关键词：土壤样品地衣种土耳其收集样品测量 alpha 平均数 Po

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