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Journal of Forestry Research 2007年第2期18卷 23-26页

作者： M.M. Rahman H. Vacik F. Begum A. Nishad k.k. Islam Institute of Silviculture University of Natural Resources and Applied Life SciencesViennaAustria Department of Agronomy Bangladesh Agricultural UniversityMymensingh-2202. Bangladesh IUCN Bangladesh Department of Agroforestry Bangladesh Agricultural UniversityMymensingh-2202. Bangladesh

The structural diversity of different tree-crop associations were studied at Gachabari Sal forest area of Madhupur Garh on Buffer and Peripheral Zone during 2006. The total density, basal area of trees in the Buffer and Peripheral Zone were 155.5 trees·hm^(-2), 795.4 trees·hm^(-2) and 3.9 m2·hm-2, 5.8 m^2·hm^(-2), respectively. No regeneration and natural trees were found in Peripheral Zone and the Zone is totally occupied by exotic species where the Buffer Zone comprised of both natural and exotic trees. The Peripheral Zone belonged to younger and smaller trees whereas the Buffer Zone belonged to mixture of smaller, taller, younger and mature trees simultaneously. For the practicing of different agroforestry systems both Zones have lost their original characters of Sal forest.

关键词：孟加拉国天然林区周边地区缓冲区林木-作物群丛结构多样性立木结构

Influence of graphene nanoplatelets on mechanical properties and adhesive wear performance of epoxy-based composites

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Friction 2021年第4期9卷 856-875页

作者： k.Y.EAYAL AWWAD B.F.YOUSIF khosro FALLAHNEZHAD khalid SALEH Xuesen ZENG Faculty of Health Engineering and SciencesUniversity of Southern QueenslandToowoombaQLDAustralia Centre for Future Materials University of Southern QueenslandToowoombaQLDAustralia School of Mechanical and Mining Engineering University of QueenslandBrisbaneQLDAustralia

Epoxy resin is one of the most widely used thermoset polymers in high-performance composite materials for lightweight ***,epoxy has a high coefficient of friction,which limits its tribological *** this study,the effect was investigated of different weight fractions of solid lubricant graphene nanoplatelets(GNPs),ranging from 0 to 4.5 wt%,on mechanical and adhesive wear performance of *** wear tests covered mild and severe wear *** correlation of tribological and mechanical properties was studied as *** electron microscopy(SEM)was used to observe the failure mechanisms for both tribological and mechanical samples after each *** results revealed that the addition of GNPs to the epoxy improved its stiffness and hardness but reduced its fracture strength and *** wear performance exhibited high efficiency with GNP additions and showed reductions in the specific wear rate,the coefficient of friction,and the induced interface temperature by 76%,37%,and 22%,respectively.A fatigue wear mechanism was predominant as the applied load *** importantly,severe wear signs occurred when the interface temperature reached the heat distortion temperature of the *** tribological,and mechanical properties showed only a weak correlation to each *** addition of GNPs to epoxy by less than 4.5 wt%was highly efficient to improve the wear performance while maintaining the fracture strength and *** transform infrared spectroscopy(FTIR)analysis shows no chemical interaction between the epoxy matrix with GNPs,which implies its physical interaction.

关键词： graphene nanoplatelets epoxy adhesive wear solid lubricants

Long range electromagnetic field nature of nerve signal propagation in myelinated axons

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Chinese Physics B 2022年第3期31卷 619-623页

作者：翟卿伟黄健安许胜勇翁宗经 School of Electrical and Computer Engineering Xiamen University MalaysiaSelangor Darul Ehsan 43900Malaysia Department of Physics Xiamen University MalaysiaSelangor Darul Ehsan 43900Malaysia Department of Electronics School of Electronics Engineering and Computer SciencePeking UniversiyBeijing 100871China Department of Physics National University of Singapore2 Science Drive 3117551 Singapore

The nature of saltatory conduction in myelinated axon described by equivalent circuit and circuit theory is still contentious. Recent experimental observations of action potentials transmitting through disjointed nerve fibers strongly suggest an electromagnetic wave propagation mechanism of the nerve signals. In this paper, we employ the electromagnetic wave model of the myelinated axon to describe action potential signal propagation. We use the experimental frequency-dependent conductivity and permittivity values of the nerve tissues in order to reliably calculate the electromagnetic modes by using electromagnetic mode solvers. We find that the electromagnetic waves above 10 kHz can be well confined in extracellular fluid–myelin sheath–intracellular fluid waveguide and propagate a distance of 7 mm without much attenuation. Our study may serve as one of the fundamental researches for the better understanding of the nervous system.

关键词： action potential propagation and axons neuronal wave propagation neuroscience electrodynamics in the nervous system

Bubble-like Fe-encapsulated N,S-codoped carbon nanofibers as efficient bifunctional oxygen electrocatalysts for robust Zn-air batteries

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Nano Research 2020年第8期13卷 2175-2182页

作者： Yiyi She Jin Liu Hongkang Wang Li Li Jinsong Zhou Michael k.H.Leung Ability R&D Energy Research Centre School of Energy and EnvironmentCity University of Hong KongHong KongChina Center of Nanomaterials for Renewable Energy(CNRE) State Key Lab of Electrical Insulation and Power EquipmentSchool of Electrical EngineeringXi’an Jiaotong UniversityXi’an710049China School of Automotive and Traffic Engineering Jiangsu University of TechnologyChangzhou213001China

Nano Research volume 13,pages2175–2182(2020)Cite this article 208 Accesses 1 Altmetric Metrics details Abstract Efficient,robust and cost-effective bifunctional oxygen electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are of vital importance to the widespread utilization of Zn-air *** we report the fabrication of a bubble-like N,S-codoped porous carbon nanofibers with encapsulated fine Fe/Fe5C2 nanocrystals(∼10 nm)(FeNSCs)by a facile one-pot pyrolysis *** novel FeNSC nanostructures with high Fe content(37.3 wt.%),and synergetic N and S doping demonstrate remarkable ORR and OER catalytic activities in alkaline *** for ORR,the optimal FeNSC catalyst exhibits superior performance in terms of current density and durability in both alkaline and acidic ***,as catalysts on the air electrodes of Zn-air batteries,the optimal FeNSCs show a high peak power density of 59.6 mW/cm^2 and extraordinary discharge-charge cycling performance for 200 h with negligible voltage gap change of only 8%at current density of 20 mA/cm,surpassing its noble metal counterpart(***).The impressive battery stability can be attributed to favorable electron transfer resulting from appropriate graphitization of the bubble-like carbon nanofibers and thorough protection of Fe/Fe5C2 nanoparticles by carbon wrapping to prevent oxidation,agglomeration and dissolution of Fe nanoparticles during battery *** present FeNSC catalyst,which is highly active,robust yet affordable,shows promising prospects in large-scale applications,such as metal-air batteries and fuel cells.

关键词： bifunctional catalyst heteroatom doping FeNSC catalyst oxygen reduction reaction oxygen evolution reaction

Enhanced thermoelectric performance of spark plasma sintered p-type Ca_(3-x)Y_(x)Co_(4)O_(9+δ)systems

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Journal of Materials Science & Technology 2020年第20期52卷 212-222页

作者： J.S.Cha D.H.kim H.Y.Hong k.Park Faculty of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul05006Republic of Korea

Highly textured dense Ca3-xYxCo4 O9+δ(0≤x≤0.3)samples were fabricated by combining sol-gel process with spark plasma sintering(SPS).Y^3+substitution for Ca^2+simultaneously increased the Seebeck coefficient and reduced the thermal *** latter was attributed to the increase in lattice anharmonicity,structural distortion,and grain boundary area,which enhanced the phonon ***2.7Y0.3Co4 O9+δshowed the largest dimensionless figure-of-merit(ZT=0.194)at 1073 k because it had the largest Seebeck coefficient and the lowest thermal *** ZT value was 55%larger than that of undoped Ca3 Co4 O9(0.125 at 1073 k).Therefore,Y^3+substitution,sol-gel powder synthesis,and SPS are highly effective for enhancing the thermoelectric prope rties of Ca_(3)Co_(4)O_(9).

关键词： Electrical conductivity Ca_(3)Co_(4)O_(9) Thermoelectric properties Seebeck coefficient Thermal conductivity Spark plasma sintering

Bacillus sp. probiotic supplementation diminish the Escherichia coli F4ac infection in susceptible weaned pigs by influencing the intestinal immune response, intestinal microbiota and blood metabolomics

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Journal of Animal Science and Biotechnology 2020年第1期11卷 95-110页

作者： Diana Luise Micol Bertocchi Vincenzo Motta Chiara Salvarani Paolo Bosi Andrea Luppi Flaminia Fanelli Maurizio Mazzoni Ivonne Archetti Giuseppe Maiorano Bea k.k.Nielsen Paolo Trevisi Department of Agricultural and Food Sciences University of BolognaViale G.Fanin 4640127 BolognaItaly Department of Agricultural Environmental and Food SciencesUniversity of MoliseVia F.De SanctisCampobassoItaly Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia Romagna Bruno Ubertini V.Bianchi 925124 BresciaItaly Endocrinology Unit and Center for Applied Biomedical Research Department of Medical and Surgical SciencesUniversity of Bologna–S.Orsola-Malpighi Hospitalvia Massarenti 940138 BolognaItaly Department of Veterinary Medical Sciences University of BolognaVia.Tolara di Sopra 5040064 Ozzano EmiliaItaly Chr.Hansen A/S Boege Allé10-122970 HoersholmDenmark

Background:Probiosis is considered a potential strategy to reduce antibiotics use and prevent postweaning diarrhea(PWD).This study investigated the effect of Bacillus amyloliquefaciens DSM25840 or Bacillus subtilis DSM25841 supplementation on growth,health,immunity,intestinal functionality and microbial profile of post-weaning pigs after enterotoxigenic ***(ETEC)F4 ***:Sixty-four post-weaning piglets(7748 g±643 g)were randomly al ocated to four groups:control basal diet(CO);CO+1.28×10~6 CFU/g of ***(BAA);CO+1.28×10~6 CFU/g feed of ***(BAS);CO+1 g colistin/kg of feed(AB).At day(d)7,animals were chal enged with 10~5 CFU/m L of ETEC F4 ac O149 and then fol owed for fecal score and performance until d *** was col ected at d 6,d 12 and d 21 for immunoglobulins,at d 8 for acute phase proteins,at d 8 and d 21 for metabolomics *** was sampled for morphometry,quantification of apoptosis,cel proliferation,neutral and acid mucine and Ig A secretory cel s,and microarray analysis at d *** and cecum contents were col ected for microbiota at d ***:AB and BAS reduced the fecal score impairment compared to CO(Pke(ADFI)and gain to feed ratio(G:F)did not differ between Bacil us groups and *** improved BW at d 7,d 14 and d 21,ADWG ADFI and G:F from d 0 to d 7(P<0.05).At d 8,CO had higher plasma arginine,lysine,ornithine,glycine,serine and threonine than other groups,and higher haptoglobin than AB(P<0.05).At d 21,CO had lower blood glycine,glutamine and Ig A than ***,cel s apoptosis and mucins did not *** and AB increased the vil us mitotic *** profile of BAS and AB were more similar than *** sets related to adaptive immune response were enriched in BAA,BAS and *** had enriched gene set for nuclear structure and RNA *** had a trend of higher Enterobacteriaceae in cecum than the oth

关键词： Bacil us amyloliquefaciens Bacil us subtilis Diarrhea ETEC Gut microbiota Post-weaning Transcriptomics

Electrical Conductivity of Sintered Chromia Mixed with TiO_2,CuO and Mn-Oxides

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Journal of Materials Science & Technology 2006年第2期22卷 245-251页

作者： k.El-Menshawy H.P.Buchkremer F.Tietz D.Stoever Metallurgy Dept. Atomic Energy Authority CairoEgypt Institute for Materials and Processes in Energy Systems IWV-1 Forschungszentrum Juelich GmbH JuelichGermany Institute for Materials and Processes in Energy Systems IWV-1 Forschungszentrum Juelich GmbH Juelich Germany

The electrical conductivity of sintered Cr2O3 mixed with 2% and 5% （in molar fraction） TiO2 or CuO was investigated in the temperature range 500-900℃ in air and in At/4 vol. pct H2 atmospheres. The effect of different Mn-oxides on the electrical conductivity of Cr2O3 was also studied under the same conditions. From the conductivity measurements it is established that additions of TiO2 change the defect structure of Cr2O3 and the effect of TiO2 on the electrical conductivity is controlled by TiO2 concentration as well as temperature and O2 partial pressure of the surrounding atmosphere. The conductivity of Cr2O3 increased in air and decreased in the At/H2 atmosphere by CuO additions. The effect of CuO was discussed with possible changes in the defect concentration in Cr2O3. Mixing of Cr2O3 with different Mn-oxides at the same Mn to metal atom fraction decreased the conductivity in air and in Ar/H2 atmospheres. No clear correlation between the spinel fraction and the changes in conductivity could be found.

关键词： Electrical conductivity Cr2O3 Mixing with TiO2 CuO Mn-oxides

Three-dimensional oscillation of an acoustic microbubble between two rigid curved plates

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Journal of Hydrodynamics 2021年第5期33卷 1019-1034页

作者： kawa M.A.Manmi Imad A.Aziz Arun Arjunan Rostam k.Saeed Abdolrahman Dadvand Department ofMathematics College of ScienceSalahaddin University-ErbilKurdistan RegionIraq Department of Information Technology College of Engineering and Computer ScienceLebanese French UniversityKurdistan RegionIraq Faculty of Science and Engineering University of WolverhamptonWolverhamptonUK Faculty of Mechanical Engineering Urmia University of TechnologyUrmiaIran karlsruhe Institute of Technology(kIT) Institute for Chemical Technology and Polymer ChemistryKarlsruheGermany

Understanding the near boundary acoustic oscillation of microbubbles is critical for the effective design of ultrasonic biomedical devices and surface cleaning ***,this study investigates the three-dimensional microbubble oscillation between two curved rigid plates experiencing a planar acoustic field using boundary integral method(BIM).The numerical model is validated via comparison with the nonlinear oscillation of the bubble governed by the modified Rayleigh-Plesset equation and with the axisymmetric model for an acoustic microbubble in infinite fluid ***,the influence of the wave direction and horizontal standoff distance(h)on the bubble dynamics(including jet velocity,jet direction,centroid movement,total energy,and kelvin impulse)were *** was concluded that the jet velocity,the maximum radius and the total energy of the bubble are not significantly influenced by the wave direction,while the jet direction and the high-pressure region depend strongly on *** importantly,it was found that the jet velocity and the high-pressure region around the jet in acoustic bubble are drastically larger than their counterparts in the gas bubble.

关键词： Acoustic microbubble bubble dynamics boundary integral method(BIM) two curved plates potential flow

橡胶改性沥青性能的试验研究和分析建模——以利比里亚为例

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橡胶改性沥青性能的试验研究和分析建模——以利比里亚为例

作者： Elvis S.k. Mensahn（梅杉）中南大学

学位级别：硕士

在利比里亚,由于车辆荷载的日益增多和反复作用,以及环境温度变化和降雨量大等因素的共同影响,沥青路面层在使用早期就出现了开裂、坑槽、松散剥落、永久变形和渗水等病害。因此,采用常规方法进行的路面层结构设计已不能满足使用要求,... 详细信息

在利比里亚,由于车辆荷载的日益增多和反复作用,以及环境温度变化和降雨量大等因素的共同影响,沥青路面层在使用早期就出现了开裂、坑槽、松散剥落、永久变形和渗水等病害。因此,采用常规方法进行的路面层结构设计已不能满足使用要求,采用新材料和新方法对于改善高利比里亚里面性能有重要意义。利比里亚当地有大量的废旧橡胶轮胎,污染环境,占用土地。因此本文以利比里亚Vai Town到Caldwell的路面损坏为例,试验研究了采用废弃橡胶颗粒改性沥青增强沥青混合料路用性能的方法,并采用kENLAYER编程算法预测了典型路面的结构响应,在提高路面层性能的同时又实现了固废资源的再生利用,保护了环境。论文的主要研究内容和成果如下:(1)研究了沥青含量对密级配热拌沥青(HMA)性能的影响。结果表明:沥青掺量4.8%时,沥青混合料各项性能的综合评价可以达到最佳。(2)研究了废旧橡胶颗粒对沥青混合料性能的影响。结果表明,采用180℃的温度拌合制备的沥青混合料,在60℃的性能试验测试条件下,采用4.8%沥青含量的密级配热拌沥青时,最优再生橡胶掺量约为沥青掺量的12%。废旧橡胶颗粒的使用有利于促进固废资源的循环利用,保护环境。(3)采用kENLAYER计算方法对典型路面结构的响应进行了分析,结果表明,不同的路面参数导致路面结构的结构响应存在差异。路面层厚度和材料性能可以通过解析模型进行评估,路面设计使用寿命可以通过车辆荷载和气候条件的影响进行预测。本项目的研究可以对利比里亚新建道路的路面设计提供有意义的参考。一、研究背景和意义道路基础设施承载着人员和货物的流动,为经济增长做出了重大贡献。因此,路面的长期性能变得至关重要。利比里亚的公路网全长11 423公里。该国大部分铺砌的道路通常由(柔性)沥青组成,路基上方有四个功能层。沥青道路的质量一直是人们日益关注的问题,但沥青路面结构和层厚的选择却是不全面的。相反,它主要依赖于从国际标准中采用的经验方法,在大多数情况下,没有进行任何设计研究。实证方法主要基于AASHO路试开发的经验和交通负荷、路基土和路面性能评价观测之间的简单相关性。此外,经验设计程序不能从轴载荷和各种层材料的影响来解释路面结构的行为。由于设计参数和数据输入有限,这些方法一直是描述路面性能的瓶颈。此外,利比里亚每年都会遇到潮湿和干燥的季节,这两个季节都会影响路面的耐久性,导致开裂,坑洼,永久性变形和潮湿损坏等灾害。此外,使用改性剂(技术)来改善沥青路面表面处理并未得到广泛应用。研究目标的第一部分是使用湿法工艺,用骨料形式的再生橡胶颗粒部分取代沥青粘结剂,作为致密等级HMA的替代物,以增强工程性能,改善利比里亚沥青表层性能。HMA中的橡胶颗粒始于19世纪40年代,当时天然橡胶被添加到沥青混合物中以改善路面表面。此外,对典型柔性路面进行分析建模,以计算由80 kN双轮标准轴载荷产生的路面响应。同时,应用160kN的串联轴载荷来预测在AC层底部发生的临界拉伸应变和在路基顶部的垂直压缩应变。此外,计算有关疲劳和车辙设计寿命的允许载荷重复。1.1在利比里亚和其他国家道路和高速公路解决方案必须具有持久性、可持续性和成本效益,从地方通道到农村和主要城市路线。全球路线图通常在改进材料改性,在沥青粘合剂和混合物中采用各种改性剂(技术)以及使用计算机算法进行路面性能预测方面取得实质性进展。然而,设计柔性路面系统已经从纯粹的经验方法发展到更实际的方法,包括额外的详细参数,如交通负荷和重复,车辆接触压力,材料特性,路面组成和环境条件。这些方法既基本又先进。另一种方法可以通过改变层厚度和组成来确保成功的路面设计。使用印度国家公路网的落重偏转计进行了柔性路面结构分析。各种工具,包括落重偏转计(FWD)和kGBACk,通过测量负载施加产生的挠度来评估国道上道路延伸的性能。此外,将所获得的原位弹性模量用于计算机工具以进行路面覆盖设计。路面中的减压主要与交通有关,环境因素确保了路面的使用寿命。使用计算机工具将路面指数专门表示交通负荷裂缝的在役路面状况与累积损坏系数进行比较。建议将计算机程序作为可行的分析工具,用于柔性路面的实用且具有成本效益的设计和分析。损伤分析是评估路面结构性能的另一种有意义的方法。主要由串联和三轴载荷引起的损坏,并精确模拟车辆几何形状。然而,路面设计的进步已经使用计算机代码来帮助解释许多国家的路面结构的性能,并考虑到其当地条件。对利比里亚的道路网络进行了几项研究。这些调查表明,该国已建成道路的质量令人严重关切。考虑到利比里亚的年度及每月的环境条件,气候全年都是炎热和潮湿,在某些情况下,温度超过40℃。该国每年平均降雨量为5135毫米。然而沥青作为粘合剂在促进沥青混合物的粘合性方面起着至关重要的作用。温度变化会影响沥青表层的工程性能,并变得僵硬,降低路面的耐久性能。1.2

关键词：废橡胶颗粒柔性路面分析建模结构响应路面灾害

Design of a variable frequency comb reflectometer system for the ASDEX Upgrade tokamak

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Plasma Science and Technology 2020年第6期22卷 8-14页

作者： T HAPPEL W kASPAREk P HENNEQUIN k HÖFLER C HONORÉ the ASDEX Upgrade Team Max-Planck-Institut für Plasmaphysik Boltzmannstr.285748 GarchingGermany IGVP Universität StuttgartPfaffenwaldring 3170569 StuttgartGermany Laboratoire de Physique des Plasmas CNRSÉcole PolytechniqueSorbonne UniversitéF-91120 PalaiseauFrance Physik-Department E28 Technische Universität MünchenJames-Franck-Str.185748 GarchingGermany 不详

Comb reflectometers offer the advantage of measuring several radial positions in plasma *** allows for the investigation of fast timescales during L-H transitions,I-phases,I-mode bursts,transients during heat wave propagation,etc.A drawback of many present-day systems is that they use a fixed frequency difference between the probing ***,although the central probing frequency can be varied,the probing frequency difference is usually *** new design presented in this work uses an advanced microwave generation and detection scheme,which allows for arbitrary probing frequencies and probing frequency separations.

关键词： reflectometry microwaves plasma diagnostic reflectometer turbulence