基于P2P的DERS系统的研究与实现

基于P2P的远程教育资源共享平台的定义,简单地说就是基于P2P网络或者说在P2P的网络环境中实现远程教育中的资源共享。在该课题的研究中,采用技术手段研发资源共享平台,结合C/S和P2P网络各自的优势在远程教育中有效实现资源的共享,为远程教育中优质资源的整理奠定基础。

Acquire A Full Understanding of the Guidelines for Running CAS in the New Era and Promote the Knowledge Innovation Program in An All-round Way

Editor's note: We are sorry that because of the over-crowded space in our last issue, we are delayed in presenting the second part of the report delivered by the CAS President Lu Yongxiang at the 2002 working conference of CAS. The report appears in two installments in this and the 1st issue of this volume.

Fe-Mo-B-CSINTERED STE ELS PRODUCED BY ADDITI ON OF MASTER ALLOY POWDERS

Addition of Fe B C and Fe Mo B C m aster alloy pow ders to Fe Mo B Csintered steels can ac tivate the sintering process by liquid phase sintering . The for m ation of liquid ( α- Fe + ( Fe , Mo) 2 B+ Fe3( B, C) → L) i m proves m echanical properties of the steels , and ultim ate tensilestrengths of 684 774 M Pa , i m pact energy of 47 ±7 Jand elongation of 2 5 ±0 9 were ob tained . Optim u m a mount of liquid phase exists , and alarge a mount of liquid phase will re sult in the form ation of continuous netw ork of liquid phase that is detrim ental to strength andelongation .

PRODUCTION OF ULTRA-FINEα-AL_2O_3 PO WDERSFROM AMMONIUM A LUMINUM CARBONATE HY DROXIDE

Synthesis of a m m oniu m alu min u m carbonate hydroxide ( A A C H) w as investigated usinga m m oniu m alu min u m sulfate and a m moniu m hydro carbonate as the starting m aterials . Itw as found that A A C Hcan be synthesized by adding a m m oniu m alu m inu m sulfate solution torapidly stirred a m moniu m hydro - carbonate solution at a tem perature of 30 ℃. A A C Hcantransfor m to α Al2 O3 co m pletely by calcining at 1100 ℃ for 1 hour , and the obtained po w ders , with a particle size of 100 n m , can be sintered to 98 99 % relative density at 1500 ℃for 2 hours .

Hard-to-Soft Transition in Radial Buckling of Multi-Concentric Nanocylinders

We investigate the cross-sectional buckling of multi-concentric tubular nanomaterials, which are called multiwalled carbon nanotubes (MWNTs), using an analysis based on thin-shell theory. MWNTs under hydrostatic pressure experience radial buckling. As a result of this, different buckling modes are obtained depending on the inter-tube separation d as well as the number of constituent tubes N and the innermost tube diameter. All of the buckling modes are classified into two deformation phases. In the first phase, which corresponds to an elliptic deformation, the radial stiffness increases rapidly with increasing N. In contrast, the second phase yields wavy, corrugated structures along the circumference for which the radial stiffness declines with increasing N. The hard-to-soft phase transition in radial buckling is a direct consequence of the core-shell structure of MWNTs. Special attention is devoted to how the variation in d affects the critical tube number Nc, which separates the two deformation phases observed in N -walled nanotubes, i.e., the elliptic phase for N Nc. We demonstrate that a larger d tends to result in a smaller Nc, which is attributed to the primary role of the interatomic forces between concentric tubes in the hard-to-soft transition during the radial buckling of MWNTs.

轻质中锰钢局部变形带的研究现状

轻质中锰钢是第三代先进高强钢的代表,在变形过程中由于C、Mn、Al等合金元素的存在其可动位错经历被固溶原子和C-Mn原子团钉扎和脱扎的过程,从而在应力-应变曲线上呈现出吕德斯(Lüders)带和Portrvin-Le Chatelier(PLC)带这两种最典型的局部变形带,导致材料表面质量降低,对后续加工使用不利。目前,消除Lüders带和PLC带引起的表面缺陷的常用方法是在成形前对材料施加小的预应变或者调控材料的组织。然而这种方法只适用于经历小Lüders带应变和PLC效应的材料,因此寻求一种更为有效的延迟或消除Lüders带与PLC带的方法显得极其重要。本文从发生机理入手,讨论预应变、退火温度、退火时间等工艺和合金元素对上述两种局部变形带的影响,进而从晶粒尺寸、组织形貌、位错密度等微观角度总结减弱或加剧二者的具体机制,并着重解释不同成分与热处理工艺对C-Mn原子团形成、移动速率和与位错交互时间的影响以及抑制局部变形带的形成与拓展的作用。随后根据已有研究提出的不同解决方案,结合上述宏观与微观影响因素,展望了未来该领域研究的发展。

NiTi-NbTi原位复合材料的Lüders带型变形和载荷转移行为

采用电弧熔炼、锻造和拔丝方法原位合成了一种高Nb含量的NiTi-NbTi记忆合金复合材料。TEM显微分析显示,在材料内部纳米尺度的NbTi和NiTi纤维沿丝材轴向交替分布,NbTi纤维体积分数高达约70%。通过同步辐射高能X射线原位拉伸实验研究了复合材料的变形机制。结果显示,虽然NiTi体积分数仅约30%,但复合材料的变形仍受NiTi的应力诱发相变控制。在加载初期,复合材料先发生均匀变形,并且在拉伸曲线出现屈服平台之前,NiTi已发生均匀相变。当平台出现之后,NiTi转而发生Lüders带型相变,进而诱发NbTi也随之发生Lüders带型变形,使整个复合材料都展现Lüders带型变形。Lüders带前沿存在载荷转移现象,载荷由正在发生相变的B2-NiTi同时转移到NbTi相及之前在均匀相变过程中形成的B19’-TiNi马氏体相。

On the Lüders band formation and propagation in NiTi shape memory alloys

Near-equiatomic NiTi shape memory alloys are known to exhibit Lüders-type deformation associated with a stress-induced transformation.Many studies have been conducted in the past mainly focusing on the macroscopic characteristics of the phenomenon and some theories have been proposed in the literature to explain its mechanisms,but some aspects of this phenomenon are still unclear,particularly at the microscopic scale.This study investigated the local strain evolution during the initiation and propagation of Lüders band in a pseudoelastic NiTi alloy during tensile deformation by means of digital image correlation(DIC)analysis.Based on the evidence collected,distinct stages of Lüders band formation and propagation are defined and the corresponding local strain rates are obtained.These local strain rates are much higher than the global strain rate of the testing,giving insight to the mechanism of this phenomenon.

碳化物演变对冷轧ART 0.1C-7Mn钢Lüders行为影响

采用SEM、XRD、力学性能测试等实验分析方法对冷轧中锰钢(0.1C-7Mn)在奥氏体逆相变不同温度退火过程中碳化物演变对Lüders应变的影响进行了分析。结果表明:随着退火温度的升高,碳化物先析出后溶解,在640℃退火时碳化物全部溶解,逆转变奥氏体的稳定性适中,强塑积最高为25 GPa·%。退火温度偏低导致奥氏体稳定性过高,同时碳化物会抑制位错运动,使得屈服点延伸较为明显;退火温度适中则高密度位错开始回复,变形时能持续地产生TRIP效应硬化基体,提高材料的综合性能;退火温度偏高时,碳化物的溶解导致位错对消重排,Lüders应变消失,奥氏体稳定性降低,应变诱导马氏体快速形成,导致中锰钢抗拉强度较高但均匀伸长率降低。

COL1A1突变致Van der Hoeve综合征家系的遗传和表型分析并文献复习

目的对一个常染色体显性遗传的Van der Hoeve综合征家系进行详尽的临床表型分析及基因突变检测,明确该家系的致病基因突变位点及该突变对基因编码的影响。方法对收集到的Van der Hoeve综合征家系进行包括病史、体格检查及辅助检查在内的临床资料的收集及外周血液样本的采集,并对22位家系成员进行外显子组测序以及Sanger测序,利用生物信息学软件分析数据。结果该家系共五代,各代连续发病,且每一代男女均可患病,符合常染色体显性遗传特点。该家系中12例患者均自出生时巩膜即呈蓝色且身材矮小,8例患者有骨折病史,可正常愈合,3例患者考虑有Van der Hoeve综合征所致的听力下降,12例患者的COL1A1基因第17号外显子有一个碱基的缺失(c.1128delT),使第376位后的氨基酸编码改变,在第539位提前结束氨基酸编码,该家系中10例无症状者无此突变。结论该家系患者确定为由COL1A1基因c.1128delT突变导致的Van der Hoeve综合征。

ZnSb/Ti_(3)C_(2)T_(x)MXene van der Waals heterojunction for flexible near-infrared photodetector arrays

Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene based flexible NIR photodetector array via a facile photolithography technology.The single ZnSb/Ti_(3)C_(2)T_(x)photodetector exhibited a high light-to-dark current ratio of 4.98,fast response/recovery time(2.5/1.3 s)and excellent stability due to the tight connection between 2D ZnSb nanoplates and 2D Ti_(3)C_(2)T_(x)MXene nanoflakes,and the formed 2D van der Waals heterojunction.Thin polyethylene terephthalate(PET)substrate enables the ZnSb/Ti_(3)C_(2)T_(x)photodetector withstand bending such that stable photoelectrical properties with non-obvious change were maintained over 5000 bending cycles.Moreover,the ZnSb/Ti_(3)C_(2)T_(x)photodetectors were integrated into a 26×5 device array,realizing a NIR image sensing application.

Optoelectronic Synapses Based on MXene/Violet Phosphorus van der Waals Heterojunctions for Visual‑Olfactory Crossmodal Perception

The crossmodal interaction of different senses,which is an important basis for learning and memory in the human brain,is highly desired to be mimicked at the device level for developing neuromorphic crossmodal perception,but related researches are scarce.Here,we demonstrate an optoelectronic synapse for vision-olfactory crossmodal perception based on MXene/violet phosphorus(VP)van der Waals heterojunctions.Benefiting from the efficient separation and transport of photogenerated carriers facilitated by conductive MXene,the photoelectric responsivity of VP is dramatically enhanced by 7 orders of magnitude,reaching up to 7.7 A W^(−1).Excited by ultraviolet light,multiple synaptic functions,including excitatory postsynaptic currents,pairedpulse facilitation,short/long-term plasticity and“learning-experience”behavior,were demonstrated with a low power consumption.Furthermore,the proposed optoelectronic synapse exhibits distinct synaptic behaviors in different gas environments,enabling it to simulate the interaction of visual and olfactory information for crossmodal perception.This work demonstrates the great potential of VP in optoelectronics and provides a promising platform for applications such as virtual reality and neurorobotics.

尘螨过敏原Der p 2线性表位肽及其硝基化产物与IgE结合能力

许多过敏原可以介导Ⅰ型超敏反应,通过与IgE特异性结合,引起过敏症状.过敏原与细胞表面的特异性IgE结合的部分叫做表位,其与IgE的结合能力可以表征过敏原致敏性的强弱.Der p 2是一种重要的屋尘螨过敏原,其线性表位中含有的酪氨酸可被空气中的NO_(2)和O_(3)硝基化,从而影响线性表位与IgE的结合能力.本实验研究了Der p 2的线性表位及其硝基化产物与IgE的结合能力.研究发现,Der p 2的两条表位多肽可以有效地结合IgE,硝基化表位多肽的IgE结合能力显著高于未硝基化的表位多肽,且不同位点的硝基化对于IgE结合能力的增强程度也不同.结果表明,硝基化能够位点特异性地增强Der p 2的致敏性.

Modeling challenges and potential solutions for integration of emerging DERs in DMS applications: power flow and short-circuit analysis

We aim to systematically review challenges imposed by emerging distributed energy resources(DERs)to model in two basic distribution management system(DMS)online applications—power flow and short-circuit analysis,as well as to offer a systematic review of potential solutions.In the last decade,electronically coupled DERs became increasingly popular.DERs can employ a wide range of control strategies for power,current,or voltage control,in both normal and faulted conditions.Therefore,DERs cannot be modeled with the traditional PQ(load or generator bus)or PV(generator bus)bus types used for modeling synchronous and induction machines in online power flow calculations.Moreover,since fault currents of DERs are limited to predefined maximal values,electronically coupled DERs cannot be represented with traditional voltage source behind impedance models for online short-circuit calculation(SCC).However,most of the DMS software packages still use the traditional models to represent all DER types,including those that are electronically coupled.This paper shows that there will be large calculation errors in such practice,which make the system model an inadequate representation of the system.This will lead to serious errors in the management,control,and operation of distribution systems.Nonetheless,potential solutions to the challenges are systematically reviewed.Finally,the calculation results on a distribution test system with all DER types are used to prove the claim.

粉尘螨变应原Der f 36重组蛋白制备及其与Der p 36的交叉反应性研究

目的:制备粉尘螨变应原第36组分(Der f 36)重组蛋白,鉴定其免疫原性并进行生物信息学分析。方法:获得Der f 36核酸序列并进行人工合成,插入pET-28a(+)载体,制备pET-28a(+)-Der f 36质粒,转化至BL21(DE3)感受态细胞,经诱导表达和纯化后,获得重组变应原rDer f 36,SDS-PAGE和Western blot鉴定rDer f 36重组蛋白,IgE-ELISA检测其血清IgE结合率,IgE-ELISA抑制实验检测rDer f 36与rDer p 36的交叉反应性;HNEpC细胞与rDer f 36共孵育24 h后测定细胞因子;生物信息学软件比较Der f 36与Der p 36的理化性质和结构。结果:得到了Der f 36的编码基因,全长690 bp,相对分子质量为25.6 kD;IgE-ELISA鉴定rDer f 36血清IgE结合率为42.1%;IgE-ELISA抑制实验结果显示rDer p 36对rDer f 36的抑制率>50.00%[40.00%(8/20)],平均抑制率为52.98%。HNEpC细胞与rDer f 36共孵育后,IL-6、IL-8、IL-33、IL-25和TSLP表达均高于对照组。生物信息学分析显示Der f 36和Der p 36的序列一致性为77.63%,理化性质较为相似;二级结构分析结果显示二者均含有α螺旋、β转角和无规则卷曲,且无规则卷曲含量最高;C2结构域显示高度重叠(RMSD=0.046)。结论:成功制备了rDer f 36重组蛋白,且具有免疫原性,为粉尘螨变应原单组分诊断及治疗奠定了基础。Der f 36与Der p 36的理化性质、二级结构和三级结构高度相似,决定其具有交叉反应性。

Two-Dimensional Materials for Highly Efficient and Stable Perovskite Solar Cells

Perovskite solar cells(PSCs)offer low costs and high power conversion efficiency.However,the lack of long-term stability,primarily stemming from the interfacial defects and the sus-ceptible metal electrodes,hinders their practical application.In the past few years,two-dimensional(2D)materials(e.g.,graphene and its derivatives,transitional metal dichalcogenides,MXenes,and black phosphorus)have been identified as a promising solution to solving these problems because of their dangling bond-free surfaces,layer-dependent electronic band structures,tunable functional groups,and inherent compactness.Here,recent progress of 2D material toward efficient and stable PSCs is summarized,including its role as both interface materials and electrodes.We discuss their beneficial effects on perovskite growth,energy level alignment,defect passivation,as well as blocking external stimulus.In particular,the unique properties of 2D materials to form van der Waals heterojunction at the bottom interface are emphasized.Finally,perspectives on the further development of PSCs using 2D materials are provided,such as designing high-quality van der Waals heterojunction,enhancing the uniformity and coverage of 2D nanosheets,and developing new 2D materials-based electrodes.

Unveiling the in-plane anisotropic dielectric waveguide modes in α-MoO_(3) flakes

The unique in-plane and out-of-plane anisotropy of α-MoO_(3) has attracted considerable interest with regard to potential optoelectronic applications. However, most research has focused on the mid-infrared spectrum, leaving its properties and applications in the visible and near-infrared light spectrum less explored. This study advances the understanding of waveguiding properties of α-MoO_(3) by near-field imaging of the waveguide modes along the [100] and [001] directions of α-MoO_(3) flakes at 633 nm and 785 nm. We investigate the effects of flake thickness and documented the modes' dispersion relationships, which is crucial for tailoring the optical responses of α-MoO_(3) in device applications. Our findings enhance the field of research into α-MoO_(3), highlighting its utility in fabricating next-generation optoelectronic devices due to its unique optically anisotropic waveguide.

Improving the electrical performances of InSe transistors by interface engineering

InSe has emerged as a promising candidate for next-generation electronics due to its predicted ultrahigh electrical performance.However,the efficacy of the InSe transistor in meeting application requirements is hindered due to its sensitivity to interfaces.In this study,we have achieved notable enhancement in the electrical performance of InSe transistors through interface engineering.We engineered an InSe/h-BN heterostructure,effectively suppressing dielectric layer-induced scattering.Additionally,we successfully established excellent metal-semiconductor contacts using graphene ribbons as a buffer layer.Through a methodical approach to interface engineering,our graphene/InSe/h-BN transistor demonstrates impressive on-state current,field-effect mobility,and on/off ratio at room temperature,reaching values as high as 1.1 mA/μm,904 cm^(2)·V^(-1)·s^(-1),and>10~6,respectively.Theoretical computations corroborate that the graphene/InSe heterostructure shows significant interlayer charge transfer and weak interlayer interaction,contributing to the enhanced performance of InSe transistors.This research offers a comprehensive strategy to elevate the electrical performance of InSe transistors,paving the way for their utilization in future electronic applications.

Critical behavior of quasi-two-dimensional ferromagnet Cr_(1.04)Te_(2)

The self-intercalation of Cr into pristine two-dimensional(2D) van der Waals ferromagnetic CrTe_(2),which forms chromium tellurides(Cr_(x)Te_(2)),has garnered interest due to their remarkable magnetic characteristics and the wide variety of chemical compositions available.Here,comprehensive basic characterization and magnetic studies are conducted on quasi-2D ferromagnetic Cr_(1.04)Te_(2) crystals.Measurements of the isothermal magnetization curves are conducted around the critical temperature to systematically investigate the critical behavior.Specifically,the critical exponents β=0.2399,γ=0.859,and δ=4.3498,as well as the Curie temperature T_(C)=249.56 K,are determined using various methods,including the modified Arrott plots,the Kouvel-Fisher method,the Widom scaling method,and the critical isotherm analysis.These results indicate that the tricritical mean-field model accurately represents the critical behavior of Cr_(1.04)Te_(2.A magnetic phase diagram with tricritical phenomenon is thus constructed.Further investigations confirm that the critical exponents obtained conform to the scalar equation near T_(C),indicating their self-consistency and reliability.Our work sheds light on the magnetic properties of quasi-2D Cr_(1.04)Te_(2),broadening the scope of the van der Waals crystals for developments of future spintronic devices operable at room temperature.

Rational design of vitamin C/defective carbon van der Waals heterostructure for enhanced activity,durability and storage stability toward oxygen reduction reaction

Metal-free defective carbon materials with abundant active sites have been widely studied as low-cost and efficient oxygen reduction reaction(ORR)electrocatalysts in metal-air batteries.However,the active sites in defective carbon are easily subjected to serious oxidation or hydroxylation during ORR or storage,leading to rapid degradation of activity.Herein,we design a van der Waals heterostructure comprised of vitamin C(VC)and defective carbon(DC)to not only boost the activity but also enhance the durability and storage stability of the DC-VC electrocatalyst.The formation of VC van der Waals between DC and VC is demonstrated to be an effective strategy to protect the defect active sites from oxidation and hydroxylation degradation,thus significantly enhancing the electrochemical durability and storage anti-aging performance.Moreover,the DC-VC van der Waals can reduce the reaction energy barrier to facilitate the ORR.These findings are also confirmed by operando Fourier transform infrared spectroscopy and density functional theory calculations.It is necessary to mention that the preparation of this DC-VC electrocatalyst can be scaled up,and the ORR performance of the largely produced electrocatalyst is demonstrated to be very consistent.Furthermore,the DC-VC-based aluminum-air batteries display very competitive power density with good performance maintenance.