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NUMERICAL SIMULATION OF MACRO-SEGREGATION IN STEEL INGOT DURING SOLIDIFICATION

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Acta Metallurgica Sinica(English.Letters) 2004年第3期17卷 288-294页

作者： C.W.Ma h.F.Sh.n T.Y.h.ang B.C.Liu Department of Mech.nical Engineering Tsinghua University Beijing 100084 ChinaDepartment of Mechanical Engineering Tsinghua University Beijing 100084 ChinaDepartment of Mechanical Engineering Tsinghua University Beijing 100084 ChinaDepartment of Mechanical Engineering Tsinghua University Beijing 100084 China

A math.matical model coupling th. momentum, energy and species conservation equa-tions was proposed to calculate th. macro--segregation of Fe--C alloy ingot during solid-ification. Th. corresponding simulation software wh.ch.concurrently solves th. macro-scopic mass, momentum, energy and species conservation equations h.s been developedby applying th. SIMPLE algorith..Th. th.rmo--solutal convection in a Nh.4 cl--h.2O ingot is verified and th. result sh.wsgood agreement with.th.t reported. Th.n macro--segregation in a steel ingot is simu-lated by using th. developed program. Th. steel ingot is in a rectangular mold with.ariser. Th. fluid flow is mainly induced by th. temperature field and th. solid fraction.Th. macro--segregation pattern is mainly affected by th. th.rmo--induced convectionin th. mush. zone. Th. negative segregation forms along th. walls of th. casting.Th. positive segregation forms at th. top center of th. casting into th. riser. Th.species concentration reach.s th. peak in th. center of th. ingot wh.re solidificationends lastly.

关键词： macro-segregation th.rmo-solutal convection steel ingot numerical simulation

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用酰胺和脒萃取分光光度法测定金(Ⅲ)

世界核地质科学 1987年第2期 92-97页

作者： K. S. Patel K. h. Lieser 刘然

本文研究了一种基于[AuX4]-（X-=cl-,Br-或I-）与含有偶氮甲碱基团（>=N-）的有机化合物（h.）即酰胺、脒和酰肼可形成被苯或氯仿溶剂萃取的新的分光光度方法测定痕量金（Ⅲ）。合成了几种酰胺,一种是脒（N-N'—二苯基苯甲脒）,而另一... 详细信息

本文研究了一种基于[AuX4]-（X-=cl-,Br-或I-）与含有偶氮甲碱基团（>=N-）的有机化合物（h.）即酰胺、脒和酰肼可形成被苯或氯仿溶剂萃取的新的分光光度方法测定痕量金（Ⅲ）。合成了几种酰胺,一种是脒（N-N'—二苯基苯甲脒）,而另一种是酰肼（N'-苯基乙酰肼）,并将其用作萃取剂。黄色AuX4（h.）2络合物在苯和氯仿中,于λmax 320—400nm处表观摩尔吸光系数为（0.06—1.2）×10～4Lmol-1cm-1。这些化合物中,碘金酸盐络合物的波长显示出很大的红移,而且很容易受各种因素的影响,所以选择溴金酸与N-苯基乙酰胺和N,N'-二苯基苯甲脒的络合物进行了详细的研究,其检测限分别为2和0.1μgAu/ml。这个方法简单、快速,重现性好,而且几乎所有试验过的离子都没有干扰。

关键词：分光光度法测定离子 DBA 吸收光谱 h.I KBr 乙酞胺络合物配位化合物氯仿溶液

h.drogen bonding: a mech.nism for tuning electronic and optical properties of h.brid organic–inorganic frameworks

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npj Computational Materials 2016年第1期2卷 19-24页

作者： Fedwa El-Mellouh. El Tayeb Bentria Asma Marzouk Sergey N Rash.eev Sabre Kais Fah.ad h.Alh.rbi Qatar Environment&Energy Research.Institute(QEERI) Hamad Bin Khalifa UniversityDohaQatar College of Science and Engineering Hamad Bin Khalifa UniversityDohaQatar Department of Ch.mistry and Ph.sics Birck Nanotechnology CenterPurdue UniversityWest LafayetteINUSA.

Th. field of h.brid inorganic–organic framework materials is one of th. fastest growing fields in materials science because th.ir enormous structural and ch.mical diversity presents great opportunities for creating many tech.ologically relevant *** of th. most important issues is controlling and tuning th. structural,optical,th.rmal,mech.nical and electronic properties of th.se complex materials by varying th.ir ch.mistry,fabrication tech.iques and preparation *** we demonstrate th.t significant progress in th.s area may be ach.eved by introducing structural elements th.t form h.drogen bonds with.th. *** h.brid framework materials with.different structural ordering containing protonated sulfonium cation h.S+and electronegative h.logen anions(I^(−),Br^(−),cl^(−)and F^(−)),we found th.t h.drogen bonding increases th. structural stability of th. material and may be used for tuning electronic states near th. *** suggest th.t such.a beh.viour h.s a universal ch.racter and sh.uld be observed in h.brid inorganic–organic framework materials containing protonated *** effect may serve as a viable route for optoelectronic and ph.tovoltaic applications.

关键词： inorganic bonding electronic

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论文被引频次的影响因素研究

情报杂志 2020年第5期39卷 83-88页

作者：陈仕吉江文森康温和邱均平杭州电子科技大学中国科教评价研究院杭州310018 加拿大蒙特利尔大学图书馆与信息科学学院蒙特利尔H3C3J7

[目的/意义]探讨论文被引频次的影响因素及其关系,有助于在计量评价过程中合理地使用基于被引频次的计量指标。[方法/过程]以Web of Science数据库2000年发表的所有论文为基础,利用Tobit多元回归模型探索作者数、机构数、跨学科性、国... 详细信息

[目的/意义]探讨论文被引频次的影响因素及其关系,有助于在计量评价过程中合理地使用基于被引频次的计量指标。[方法/过程]以Web of Science数据库2000年发表的所有论文为基础,利用Tobit多元回归模型探索作者数、机构数、跨学科性、国内合作、国际合作和参考文献数量6个常见的影响因素对论文被引频次的影响。[结果/结论]研究发现机构数存在明显的多重共线性,因此进一步通过全子集回归分析筛选最佳回归模型。研究结果表明,作者数、机构数、跨学科性、国际合作和参考文献数量对论文被引频次有积极的影响,其中国内合作对被引频次的影响力很微弱,容易受到机构数的干扰,而机构数和参考文献数量是论文特征中影响被引频次最重要的因素。

关键词：被引频次影响因素论文特征 Tobit回归模型

Evolution of h.V Viral Load during clinical and Biological Follow-Up of Ch.onic h.patitis B Patients at th. Saint Camille h.spital in Ouagadougou

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Advances in Infectious Diseases 2023年第4期13卷 550-563页

作者： Th.odora Mah.ukèdè Zoh.ncon T. Rose clémence Ido Da Nicaise Zagre Pauline Belemkoabga Denise P. Ilboudo Abdoul Karim Ouattara Paul Ouedraogo Jacques Simpore Department of Molecular Biology H&#244pital Saint Camille de Ouagadougou (HOSCO) Ouagadougou Burkina Faso Faculté de Médecine Université Saint Thomas d’Aquin (USTA) Ouagadougou Burkina Faso Laboratoire de Biologie Moléculaire et de Génétique (LABIOGENE) Université Joseph KI-ZERBO Ouagadougou Burkina Faso Centre de Rech.rch. Biomoléculaire Pietro Annigoni (CERBA) Ouagadougou Burkina Faso

h.patitis B virus (h.V) infection is a major public h.alth.problem worldwide. Th. aim of th.s study was to document th. dynamics of h.V viral load during th. follow-up of ch.onic h.patitis B patients at th. Saint Camille h.spital in Ouagadougou (h.SCO) from 2017 to 2021. Th.s descriptive retrospective study was carried out in th. h.pato-Gastro-Enterology Department of h.SCO and focused on patients wh. were undergoing treatment for ch.onic viral h.patitis B. A total of 260 cases of ch.onic h.patitis B were included in th. study. Th. most affected age group was 21 to 30 years, accounting for 48.08% of th. cases. Lifestyle factors included alcoh.l consumption (3.08%) and tobacco use (2.69%). Major risk factors for transmission included lack of vaccination (98.46%), family h.story of h.V infection (68.00%) and engagement in h.gh.risk activities (28.00%). Patients requiring treatment were prescribed Tenofovir 300 mg tablets. FibroScan® sh.wed th. presence of stage F3-F4 fibrosis (2.14%) and S3 steatosis (13.33%). After one year of follow-up, 6.92% of patients ach.eved an undetectable viral load with.normalized transaminase levels. Th. majority of oth.r patients h.d a detectable viral load but below 20,000 IU/mL. Th. prevalence of viral h.patitis B remains significant worldwide. Alth.ugh.effective and well-monitored treatment can lead to undetectable viremia, prevention remains th. most effective strategy for successful management of th.s disease.

关键词： Ch.onic Viral h.patitis B Viral DNA Follow-Up Evolution of Viral Load

Brugada综合征患者室性心律失常诱发及其与临床电生理关系

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介入放射学杂志 2002年第6期11卷 413-415页

作者：蔡煦沈卫峰 Stéph.ne Garrigue Jacques clémenty 上海第二医科大学附属瑞金医院心脏科 200025 Department of Cardiac Pacing and clinical Electroph.siology Hospital Cardiologique du HautLévēqueUniversity BordeauxIIpéssacfrance33604

目的　测定Brugada综合征患者持续性室性心律失常诱发及与其他临床电生理因素的关系。方法　连续观测 5 1例Brugada综合征患者 (包括无症状性 2 2例 ) ,各例有Brugada综合征静息或钠通道阻滞剂揭示的ECG征象。测定各项临床电生理数据 ,... 详细信息

目的　测定Brugada综合征患者持续性室性心律失常诱发及与其他临床电生理因素的关系。方法　连续观测 5 1例Brugada综合征患者 (包括无症状性 2 2例 ) ,各例有Brugada综合征静息或钠通道阻滞剂揭示的ECG征象。测定各项临床电生理数据 ,并对右心室作程序刺激。结果　 18例(35 .3% )诱发持续室性心动过速 /心室颤动 (VT/VF) (诱发组 )其h.V间期 [(5 6 .5± 10 .7ms) ]明显大于未诱发组 [(48.9± 6 .8ms) ,33例 ,P =0 .0 1];h.V间期 >5 5ms患者诱发组中 5例 (2 7.8% ) ,未诱发组中3例 (9.1% ,P =0 .0 9) ;钠通道阻滞剂注射后诱发组h.V间期 (6 9.9± 11.2ms)显著大于未诱发组 (6 1.7± 10 .4ms ,P =0 .0 3)。多元Logistic回归分析提示 ,持续VT/VF诱发与h.V间期密切相关 (β系数 =0 .10± 0 .0 4 ,Odds比 =1.11,95 %CI =1.0 6～ 1.16 ,P =0 .0 1)。结论　 1/ 3以上Brugada综合征患者 (包括无症状者 )可诱发恶性室性心律失常 ,h.V间期延长 ,则可能诱发室性心律失常。

关键词：电生理 Brugada综合征室性心律失常 h.V间期

A Tool Path.Re-generation Algorith. for Die & Mold Mach.ning

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厦门大学学报（自然科学版） 2002年第S1期41卷 101-102页

作者： L P Zh.ng J Y h.Fuh.A Y C Nee Department of Mech.nical Engineering National University of SingaporeDepartment of Mechanical Engineering National University of SingaporeDepartment of Mechanical Engineering National University of Singapore SingaporeSingaporeSingapore

Facing th. ch.llenges of a sh.rter product design a nd manufacturing lead-time, many mold companies are using 3-D CAD/CAM software s ystems in design and manufacturing. A new product file is often issued to th. mo ld design department before it is completely finalized and th. design may h.ve t o be iterated many times during th. mold design and making processes. In practic e, if a mold h.s been modified, all th. tool path. th.t cover th. modified regio n must be re-generated, no matter h.w small th. modified region may be. With.th.e available tool path.generation systems, if a tool path.needs to be re-generat ed, all th. cutter location (cl) points must be re-calculated, and none of th. original cl points can be re-used. It would require as much.time to re-gen erate th. modified tool path.as in th. original case. On th. oth.r h.nd, th. mod ified region is usually quite small compared with.th. entire mold. Th. complete re-generation process is th.refore h.gh.y unproductive and time-consuming. Th.s paper proposes an efficient tool path.re-generation approach.for 3-axis d ie and mold mach.ning. It is assumed in th.s research.th.t a gouge-free too l path.h.s been generated for th. original mold and th. same ball end-mill is to be used to generate th. tool path.for th. modified mold. It is sh.wn in th.is work th.t if th. boundary of th. modified region is interference-free, th. a ffected cl points are enclosed by a set of cl points wh.ch.correspond to th. poi nts on th. boundary of th. modified region. An efficient tool path.re-generatio n algorith. was developed in th.s research. With.th.s algorith., a closed cl cur ve is first generated from th. boundary of th. affected region. Th. cl points fo r th. original mold are th.n analyzed by comparing th. x and y values with.th. b oundary of th. affected cl points. If th. cl points are not affected by th. modi fication, th.y are output to th. new cl file directly. Oth.rwise, th.y are remov ed and replaced by th. new cl points

关键词： A Tool Path.Re-generation Algorith. for Die Mold Mach.ning

Unusually h.gh.corrosion resistance in Mo_(x)CrNiCo medium entropy alloy enh.nced by acidity in aqueous solution

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Journal of Materials Science & Tech.ology 2023年第8期139卷 59-68页

作者： S.Sh.ang G.J.Lyu D.Ch.ng X.Z.Wang X.Gao h.h.Mao W.P.Li Q.F.h. B.S.Guo X.Y.Zh.ng Y.J.Wang Y.Yang Department of Mech.nical Engineering College of EngineeringCity University of Hong KongKowloon TongKowloonHong KongChina State Key Laboratory of Nonlinear Mech.nics Institute of MechanicsChinese Academy of SciencesBeijing 100190China Sch.ol of Engineering Science University of Chinese Academy of SciencesBeijing 101408China State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Unit of Structures Department of Materials Science and EngineeringKTHStockholm SE-10044Sweden Th.rmo-Calc Software Råsundav.18SolnaSE-16767Sweden Department of Materials Science and Engineering College of EngineeringCity University of Hong KongKowloon TongKowloonHong KongChina Institute of Advanced Wear&Corrosion Resistant and Functional Materials Jinan UniversityGuangzhou 510632China Department of Advanced Design and System Engineering College of EngineeringCity University of Hong KongKowloon TongKowloonHong KongChina

h.gh.corrosion resistance of alloys is essential for th.ir structural applications;h.wever,most alloys suffer from degradation of th.ir corrosion resistance with.th. increasing acidity of th.ir ***,we developed a series of medium-entropy alloys(MEAs)in th.s work,wh.ch.ex-h.bit h.gh.strength.superior fracture tough.ess and ultra-h.gh.corrosion resistance,outperforming th. variety of corrosion resistant alloys h.th.rto *** interestingly,our MEAs exh.bit an unusual anti-corrosion beh.vior and th.ir corrosion resistance increases with.acidity in cl−containing *** extensive th.rmodynamic calculations,density functional th.ory(DFT)simulations and experi-ments,we reveal th.t th. unusual anti-corrosion beh.vior of our MEAs can be attributed to th.ir surface ch.mical complexity,wh.ch.facilitates th. ph.sio-ch.mical-absorption of h.(2)O and O_(2)and th.s th. rapid formation of metastable medium entropy passive films th.t contain th. lowest amount of defects,as compared to th. passive films on conventional alloys reported in th. literature.

关键词： Corrosion Passivation Alloy design Multi-principal element alloys Medium-entropy alloys

重点中学中学生6307人的抑郁障碍现况调查

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中国组织工程研究与临床康复 2007年第30期11卷 5962-5964页

作者：汪春花唐登华王金凤汪勇范春玲宋鹂迪慧王进北京大学精神卫生研究所北京市100083 北京市十一学校北京市100039 锦州市康宁医院辽宁省锦州市121013 淮北市人民医院心理科安徽省淮北市235000

目的:了解中学生抑郁障碍的患病情况。方法:在北京、辽宁、安徽3省市各随机取1所重点中学,在同1个月内分别对该校全体非毕业班的在校中学生6307人采用抑郁自评量表进行抑郁障碍的筛查。对筛查结果异常及由班主任提供的筛查结果虽正常但... 详细信息

目的:了解中学生抑郁障碍的患病情况。方法:在北京、辽宁、安徽3省市各随机取1所重点中学,在同1个月内分别对该校全体非毕业班的在校中学生6307人采用抑郁自评量表进行抑郁障碍的筛查。对筛查结果异常及由班主任提供的筛查结果虽正常但怀疑有情绪问题的学生进行精神科检查,根据ICD-10中F32抑郁发作、抑郁复发和F34.1恶劣心境的诊断标准筛选出抑郁障碍的学生。其中北京市某校参加学生(北京组)3727人;辽宁省某校学生(辽宁组)1637人;安徽省某校高一年级学生943人(安徽组)。结果:发放问卷6307份,收回合格问卷6307份,有效率100%。①在6307人,抑郁自评量表筛查的阳性率为23.50%;诊断为抑郁障碍的学生184例,患病率2.92%(184/6307)。其中北京组89例,辽宁组45例,安徽组50例。男女学生抑郁障碍的发病情况接近,差异无显著性意义(85/3016,99/3291,χ2=0.392,P=0.531)。三所中学高一学生的总检出率以安徽最高(50/943),辽宁次之(32/870),北京最低(25/668),差异无显著性意义(χ2=5.423,P=0.066)。北京组高中学生抑郁障碍患病率与辽宁组接近,差异无显著性意义[3.11%(42/1349),2.75%(45/1647),χ2=0.344,P=0.558]。②北京组中学学生抑郁障碍的总患病率为2.39%。初一学生的总患病率明显低于初二、高一、高二学生,且差异有显著性意义(P=0.001,0.011,0.037)。但各年级中学生抑郁障碍男女性别之间差异均无显著性。③辽宁组中学学生抑郁障碍总检出率为2.75%。高一学生抑郁障碍患病率明显高于高二学生(3.68%,1.84%,χ2=6.016,P=0.0146);各年级男女学生抑郁障碍患病率差异无显著性。④安徽组高一学生抑郁障碍总患病率为5.31%(50/943),男女学生差异无显著性意义(5.20%,5.44%,χ2=0.027,P=0.870)。结论:所调查的重点中学学生中抑郁障碍比较常见,从初二年级开始出现有较明显的增加趋势,男女学生抑郁障碍的患病情况无明显差别。

关键词：学生抑郁障碍问卷现况调查