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Heat Transfer Enhancement of Supercritical Nitrogen Flowing Downward in a Small Vertical Tube:Evaluation of System Parameter Effects

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Journal of Thermal Science 2020年第6期29卷 1487-1503页

作者： ZHU xiaojing Lyu Zhihao yu xiao LI Qiang CAO Maoguo REN Yongxiang Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of TechnologyDalian 116024China Shenyang Aeroengine Research Institute Aero Engine Corporation of ChinaShenyang 110015China

In this paper,the heat transfer enhancement(HTE)of supercritical nitrogen flowing downward in a vertical small tube(diameter 2 mm)is studied using the commercial software CFX of Ansys16.1,to provide theoretical guidance on the design of high-performance heat transfer *** effective numerical simulation method,which employs the SSG Reynolds stress model with enhanced wall treatment,is applied to study the heat transfer of supercritical nitrogen under typical working *** objective is to evaluate the effect of the main parameters taking into account the buoyancy and flow acceleration *** results are compared with results calculated from three well-known empirical correlations and the applicability of empirical correlation is discussed in *** is discovered that the Watts and Chou correlation accurately fits the simulation results of supercritical nitrogen and the Dittus-Boelter and Jackson correlations can only be used for high-pressure *** HTE of supercritical nitrogen is closely related to the laminar sub-layer and buffer layer of a boundary *** buoyancy effect on the HTE should be considered at low mass flux conditions,and thermal acceleration can be completely ignored for the cases *** special HTE featured by the increment in heat transfer coefficient with increasing heat flux is discovered at low pressure,and simulation results proved that this HTE is caused by the combined actions of buoyancy as well as significant variations in specific heat and viscosity.

关键词： supercritical nitrogen heat transfer enhancement(THE) numerical simulation vertically downward flow system parameter evaluation

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玉米秸秆降解复配菌的构建及其协同效果评价

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玉米科学 2024年第6期32卷 46-54页

作者：青格尔张必周王莉杰赵文山于晓芳高聚林内蒙古农业大学/玉米秸秆原位还田微生物内蒙古自治区工程研究中心/内蒙古自治区作物栽培与遗传改良重点实验室呼和浩特010019 内蒙古自治区农牧业科学院呼和浩特010010

针对秸秆木质纤维素组成结构复杂性,充分利用不同菌株间的协同效应提升秸秆降解效率。以功能单菌株Achromobacter deleyi strain LMG 3458(A3)、Pseudomonas plecoglossicida strain NBRC(A4)、Aspergillus terreus(A)、Phanerochaete Chrysosporium(P)为试材,通过相互组配构建菌株丰度为1~4的多个复配菌,采用相关性分析和方差分析等方法探明菌株丰度对秸秆降解效率及其生物量的影响。结果表明,秸秆及木质纤维素降解率和酶活性均与复配菌组成丰度呈显著正相关关系,丰度为4时(A3+A4+A+P),其玉米秸秆、纤维素、半纤维素和木质素降解率分别为37.01%、36.27%、33.50%和31.27%,滤纸酶活性、木聚糖酶活性和漆酶活性分别为15.47、5.84和58.05 U/L,表明菌株间以及酶之间存在多样性效应。复配菌组成菌株间具有协同效应,促进秸秆高效降解,具有良好的应用前景。

关键词：玉米:复配菌秸秆降解多样性效应抽样性效应

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Enhanced electromagnetic wave absorption properties of ZIF-67 modified polymer-derived SiCN ceramics by in situ construction of multiple heterointerfaces

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Rare Metals 2023年第5期42卷 1635-1644页

作者： Tao-Bo Geng Gao-yuan yu Gao-Feng Shao xiao-Gu Huang School of Chemistry and Materials Science Nanjing University of Information Science&TechnologyNanjing210044China

Multiphase polymer-derived ceramics have the advantages of thermal stability and adjustable dielectric properties,which exhibit significant potential for use in high-temperature microwave absorbing ***,Co-containing polymer-derived SiCN(Co-SiCN)ceramics were successfully synthesized by the physical mixing of zeolitic imidazolate framework(ZIF)-67 and polysilazane precursors and subsequent *** phase and chemical compositions,microstructures,dielectric properties,electromagnetic wave absorption(EWA)performance,and mechanism of the ceramics were *** results showed that the introduction of ZIF-67 promoted the in situ formation of dielectric loss phases,including SiC nanocrystals,CoSi nanocrystals,and free *** phase composition can be regulated by controlling the pyrolysis temperature to achieve ideal EWA *** Co-SiCN ceramic pyrolyzed at 1500℃demonstrated excellent EWA performance,with a maximum effective absorption band(EAB_(max))of 3.0 GHz at an ultralow thickness of 1.05 mm and minimum reflection loss(RL_(min))of-46.4 dB at a low frequency of 6 *** with other reported SiCN-based ceramics containing magnetic metals,the ceramics prepared in this study stand out because of their low RL and high EAB at low *** superior microwave absorption performance of the Co-SiCN ceramics is attributed to the heterointerface polarization,and impedance matching induced by the synergistic effects of their co-existing electromagnetic transparent/absorption *** study provides new insights into the development of high-performance SiCNbased microwave absorbers.

关键词： Polymer-derived SiCN ceramic Multiple heterointerfaces Zeolitic imidazolate framework(ZIF-67) Electromagnetic wave absorption(EWA)

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Improved mammalian family phylogeny using gap-rare multiple sequence alignment:A timetree of extant placentals and marsupials

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Zoological Research 2023年第6期44卷 1064-1079页

作者： Gao-Ming Liu Qi Pan Juan Du Ping-Fen Zhu Wei-Qiang Liu Zi-Hao Li Ling Wang Chun-Yan Hu Yi-Chen dai xiao-xiao Zhang Zhan Zhang Yang yu Meng Li Peng-Cheng Wang xiao Wang Ming Li Xu-Ming Zhou Key Laboratory of Animal Ecology and Conservation Biology Institute of ZoologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China School of Life Sciences University of Science and Technology of ChinaHefeiAnhui 230026China College of Life Sciences Nanjing Normal UniversityNanjingJiangsu 210023China

The timing of mammalian diversification in relation to the Cretaceous-Paleogene(KPg)mass extinction continues to be a subject of substantial *** studies have either focused on limited taxonomic samples with available whole-genome data or relied on short sequence alignments coupled with extensive species *** the present study,we improved an existing dataset from the landmark study of Meredith et al.(2011)by filling in missing fragments and further generated another dataset containing 120 taxa and 98 exonic *** these two datasets,we then constructed phylogenies for extant mammalian families,providing improved resolution of many conflicting ***,the timetrees generated,which were calibrated using appropriate molecular clock models and multiple fossil records,indicated that the interordinal diversification of placental mammals initiated before the Late Cretaceous ***,intraordinal diversification of both extant placental and marsupial lineages accelerated after the KPg boundary,supporting the hypothesis that the availability of numerous vacant ecological niches subsequent to the mass extinction event facilitated rapid ***,our results support a scenario of placental radiation characterized by both basal cladogenesis and active interordinal divergences spanning from the Late Cretaceous into the Paleogene.

关键词： Mammals Phylogeny Diversification Evolutionary model

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Living Crystallization-Driven Self-Assembly of Oligo(p-phenylene vinylene)-Containing Block Copolymers:Impact of Branched Structure of Alkyl Side Chain ofπ-Conjugated Segment

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Chinese Journal of Polymer Science 2023年第4期41卷 574-584,I0008页

作者： Yang Song Bo Xiang xiao-yu Huang Guo-Lin Lu Chun Feng School of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Advanced Polymeric Materials School of Materials Science and EngineeringEast China University of Science and TechnologyShanghai200237China Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of SciencesShanghai200032China

The structure of side chains ofπ-conjugated segments is a critical factor determining living crystallization-driven self-assembly(CDSA),a versatile platform to generate fiber-like nanostructures with precise length and ***,we design and synthesize three block copolymers(BCPs)containing same corona-forming poly(N-isopropyl acrylamide)(PNIPAM)segment,but different core-formingπ-conjugated oligo(p-phenylene vinylene)(OPV)with linear pentyl(l-OPV),racemic 2-methyl butyl(r-OPV)and stereo-regular chiral(S)-2-methyl butyl(c-OPV)side chains,*** using these BCPs of l-OPV-b-PNIPAM_(47),r-OPV-b-PNIPAM_(47)and c-OPV-b-PNIPAM_(47)as model,we aim to get a deep insight into how steric and stereo-regular effect induced by branched alkyl side chains of OPV segment affects the living *** results showed that l-OPV-b-PNIPAM_(47)exhibits typical characteristics of self-seeding and seeded growth of living CDSA to give uniform fiber-like micelles of controlled *** the contrary,r-OPV-b-PNIPAM_(47)and c-OPV-b-PNIPAM_(47)with branched racemic and stereo-regular chiral alkyl side chains are more prone to self-nucleation during the micellar elongation to give short and polydisperse fiber-like *** obvious selfnucleation during the micellar elongation of r-OPV-b-PNIPAM_(47)and c-OPV-b-PNIPAM_(47)is due to the increase of steric repulsion with OPV units induced by branched alkyl side chains,not the stereo-irregular effect of racemic alkyl side chains.

关键词： π-Conjugated polymer Nanofiber Living crystallization-driven self-assembly Structure effect

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High-Temperature Oxidation Resistance of Austenitic Stainless Steel Cr18Ni11Cu3Al3MnNb

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Journal of Iron and Steel Research International 2012年第5期19卷 74-78页

作者： LI Dong-sheng dai Qi-xun CHENG xiao-nong WANG Rong-rong HUANG Yan School of Material Science and Engineering Jiangsu UniversityZhenjiang212013JiangsuChina

The kinetic curve of the high-temperature oxidation of austenitie stainless steel Crl8Ni11 Cu3Al3MnNb at different temperatures was measured by weighting method. It is showed that the oxidation curves at 700 and 800 ℃ followed the parabolic law, and the steel presented an excellent anti-oxidation. The surface morphology and structure of the oxide film were studied by scanning electron microscopy and X-ray diffraction methods. A dense oxide film was attained at 700 and 800 ℃, mainly composed of the hexagonal Al2 O3, Fe2 O3, and a small amount oxide of Cr at 700 ℃. At 900 ℃ the oxide film started to delaminate, and was composed of （Cr,Fe）2O3 and the spinel CuCrMnO4 and Fe（Cr, Al） 2O3.

关键词： austenitic stainless steel high-temperature oxidation oxidation scale cyclic oxidation spinel

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高分子医用材料设计性实验教学探索——以“光固化3D打印立体网络水凝胶支架”为例

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高分子通报 2024年第6期37卷 836-845页

作者：纪倩于小健周怡雯邱立朋陈曦陈敬华江南大学生命科学与健康工程学院无锡214122 江南大学机械工程学院无锡214122

将前沿性的科学技术引入本科实验教学已成为高校教学改革的趋势之一。3D打印作为一种新兴的制造技术,在高分子材料成型加工领域具有良好的应用价值。在生物医用材料方面,通过3D打印可以设计并制备出与患者受损组织区域相同或相似的三维... 详细信息

将前沿性的科学技术引入本科实验教学已成为高校教学改革的趋势之一。3D打印作为一种新兴的制造技术,在高分子材料成型加工领域具有良好的应用价值。在生物医用材料方面,通过3D打印可以设计并制备出与患者受损组织区域相同或相似的三维修复材料,以实现精准化和个性化医疗。结合生物医药特色,学院开展了以3D打印高分子医用材料为研究主题的设计性实验教学项目,为学生提供自主学习和实践的平台。本文采用数字光处理(DLP) 3D打印技术对光敏材料甲基丙烯酰化明胶(GelMA)和聚乙二醇二丙烯酸酯(PEGDA)进行光固化处理,制备三维网络水凝胶支架,打印的样品结构完整,孔道连通,孔径与模型相符。分析空间结构和材料配方对水凝胶支架性能的影响,结果显示500μm孔径的GelMA-PEGDA立体网络水凝胶具有较好的力学性、溶胀性以及稳定性。该设计性实验涉及多学科知识交叉融合,为师生带来了一种全新的教学体验,也为创新型人才的培养提供了一种新的思路。

关键词： 3D打印高分子材料光敏材料水凝胶设计性实验

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Variations in diversity,composition,and species interactions of soil microbial community in response to increased N deposition and precipitation intensity in a temperate grassland

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Ecological Processes 2023年第1期12卷 495-506页

作者： Shuyan Cui yushan xiao yu Zhou Pengfeng Wu Liqiang Cui Guo Zheng College of Life Science Shenyang Normal UniversityShenyang 110034China School of Environmental Science and Engineering Yancheng Institute of TechnologyYancheng 224051China

Background Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in *** addition,nitrogen(N)deposition occurs simultaneously in arid and semi-arid *** biomass,diversity,composition,and species interactions are key determinants of ecological *** examined the effects of changes in precipitation intensity and N addition on the soil bacterial and fungal communities in a semi-arid grassland in Inner Mongolia,*** The microbial biomass(bacterial PLFAs and fungal PLFAs)was determined through phospholipid fatty acid(PLFA)analysis,and microbial diversity(Shannon index and evenness index)was determined with high-throughput sequencing(16S and ITS).Species interactions were determined using a molecular ecological network *** relationships between microbial community(bacterial community and fungal community)and environmental variables were examined by Mantel *** We found that N addition decreased fungal PLFA under moderate,high,and extreme precipitation intensity treatments and increased fungal community complexity under the high precipitation intensity ***,N addition increased bacterial diversity under moderate and high precipitation intensity treatments.N addition caused greater environmental stress to the fungal community,which was dominated by deterministic *** The effects of N deposition on soil bacterial and fungal communities were altered by precipitation *** changes in soil bacterial and fungal communities were different,implying that composition and functional traits adapt differently to projected global changes at a regional scale.

关键词： Microbial community composition Phospholipid fatty acid High-throughput sequencing Precipitation intensity N deposition

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武夷-云开造山带早古生代镁铁-超镁铁质岩富钪风化壳的首次发现及其意义

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矿物学报 2024年第3期44卷 303-316页

作者：周美夫赵文周岱杨胜标申宇王振朝漆亮王敏陈伟中国科学院地球化学研究所贵州贵阳550081 中国地质大学(武汉)资源学院湖北武汉430074 中国地质调查局武汉地质调查中心湖北武汉430205

本文首次报道华南古生代武夷-云开造山带东南缘的兰排镁铁-超镁铁质岩体富钪(Sc)风化壳,初步计算获得区域内钪的潜在资源为524~566 t,为一潜在大型风化壳型钪矿。兰排岩体呈小型岩株侵入到永和闪长质岩体内,主要由橄榄岩、辉石岩和辉长... 详细信息

本文首次报道华南古生代武夷-云开造山带东南缘的兰排镁铁-超镁铁质岩体富钪(Sc)风化壳,初步计算获得区域内钪的潜在资源为524~566 t,为一潜在大型风化壳型钪矿。兰排岩体呈小型岩株侵入到永和闪长质岩体内,主要由橄榄岩、辉石岩和辉长岩组成,辉石岩锆石^(206)Pb/^(238)U年龄为(428.3±2.0)Ma(MSWD=0.92)。镁铁-超镁铁质岩全岩w(TFe_(2)O_(3))为12.1%~18.7%,其中辉石岩钪含量为44×10^(–6)~97×10^(–6),总体高于橄榄岩(20×10^(–6)~89×10^(–6))和辉长岩(28×10^(–6)~48×10^(–6))。兰排这类富钪岩石组合与以往认为富钪的碳酸岩-碱性岩体和阿拉斯加型岩体都存在较大差异,可能代表了一种新的钪成矿母岩类型,推测碰撞后陆内伸展诱发富钪地幔源区熔融可能是富钪母岩浆形成的重要机制。镁铁-超镁铁质岩体上部发育完整的风化壳剖面,可分为全风化层和半风化层。全风化层的上部富集铁(氢)氧化物(磁铁矿、赤铁矿、针铁矿),而中下部以高岭石等黏土矿物为主。半风化层除了包含蒙脱石等黏土矿物,还包括铁钛氧化物及辉石等硅酸盐矿物或相关蚀变矿物。风化壳样品的Sc含量为21×10^(–6)~304×10^(–6),富集程度最高可达相应基岩的3倍以上。其中,钪含量最高的样品主要分布在铁氧化物最富集的全风化层上部,其钪含量多数超过100×10^(–6)。风化壳钪含量与红土化指数(IOL)呈明显的正相关性,表明红土化过程对风化壳钪的富集有显著影响。初步研究认为钪在风化壳红土化过程中经历了活化-迁移-沉淀的多阶段富集过程:1)风化早期钪以类质同象替换的形式赋存在蒙脱石等黏土矿物中;2)风化后期磁铁矿和蒙脱石溶解,钪赋存在以铁(氢)氧化物为主的矿物中,并达到最高程度的富集(Sc>100×10^(–6));3)风化晚期铁(氢)氧化物溶解,一部分钪向下迁移到特定层位。兰排镁铁-超镁铁质岩体富钪风化壳的发现弥补了我国高品位风化壳型钪矿床的空白,丰富了成矿母岩的类型,为华南早古生代成矿作用的理论研究和战略性矿产的找矿勘查提供了一个新的方向。

关键词：风化壳型钪矿床武夷-云开造山带镁铁-超镁铁质岩红土化指数

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The Nature of Bonding in WC and WN

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Chinese Chemical Letters 2001年第7期12卷 655-658页

作者： Xue Mei GAO Shi Xi LIU xiao Guang XIE Huai CAO Shu Shan dai Department of Chemistry Yunnan University Kunming 650091 Modern Biological Center Yunnan University Kunming 650091

The nature of bonding in the title compounds has been studied by using CASSCF and FOCI techniques. The ground states of WC and WN are found to be 3Δ and 4∑- state arising primarily from:...1(22(21(41(13(1 and ...1(22(21(41(23(1 configuration respectively. WC shows a strong character of covalent bond while WN have obvious character of ionic bond and the dissociation energy of WN is larger than that of WC (6.15 and 5.41 eV respective).

关键词： WC and WN nature of bonding molecular constants CASSCF FOCI

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