材料期刊网

A brief review of para-xylene oxidation to terephthalic acid as a model of primary C-H bond activation

Nor Aqilah Mohd Fadzil , Mohd Hasbi Ab Rahim , Gaanty Pragas Maniam

催化学报 doi:10.1016/S1872-2067(14)60193-5

关键词:

Nω-羟基-nor-L-精氨酸的合成

滕汉兵

应用化学 doi:10.3724/SP.J.1095.2010.90811

以Nα-Boc-L-谷氨酰胺为原料,合成了精氨酸酶抑制剂Nω-羟基-nor-L-精氨酸的二盐酸盐. 合成过程由文献中7步操作整合为4步,减少了中间体的分离步骤,使总收率由21%提高至37%.

关键词: 精氨酸酶抑制剂 , 氨基保护 , 合成

Stabilizing unstable discrete systems

Physical Review E

A general method for stabilizing unstable discrete systems to a fixed point or high-period orbit is developed analytically and numerically in this paper. It is shown that the method can be equally applied to the systems with one or more positive Lyapunov exponents. Moreover, the method does not require a prior analytical knowledge of the system under investigation, nor any additional control parameters.

关键词: adaptive adjustment mechanism;high-dimensional systems;controlling;chaos;periodic-orbits;dynamical-systems;attractors

Nanoscale Morphology in Tensile Fracture of a Brittle Amorphous Ribbon

Xifeng LI , Kaifeng ZHANG , Guofeng WANG

材料科学技术（英文）

The paper reports on the observation of nanoscale morphology on the tensile fracture surface of a brittle amorphous Fe-based ribbon. The formation of nanoscale damage cavity structure is a main characteristic morphology on the fracture surfaces. Approaching the ribbon boundary, these damage cavities assemble and form the nanoscale periodic corrugations, which are neither Wallner lines nor crack front waves. The periodic corrugations result from the interactions between the reflected elastic waves by the boundaries of amorphous ribbon and the stress fields of the crack tip.

关键词: Nanoscale periodic corrugation , 断裂空洞 , 拉伸断裂

Control of hyperchaos

Physical Review E

A general method for controlling chaotic systems with one or more positive Lyapunov exponents is investigated analytically and numerically. The method retains the formal features of the adaptive adjustment mechanism and can be equally applied to various types of the unstable fixed points. It is shown that the method proposed here neither asks for any prior analytical knowledge of the system, nor any internal or external controlling parameters in advance.

关键词: adaptive adjustment mechanism;unstable periodic-orbits;high-dimensional systems;controlling chaos;dynamical-systems;stabilization;attractors

分子筛/受阻胺对膨胀阻燃聚丙烯的协同阻燃作用

李雄杰 , 刘雨 , 邹国享 , 赵彩霞 , 杨荣 , 李锦春

高分子材料科学与工程 doi:10.16865/j.cnki.1000-7555.2017.01.011

采用热失重、极限氧指数、锥形量热研究了以受阻胺(NOR116)和分子筛为协效剂,与聚磷酸铵(APP)/季戊四醇(PER)在聚丙烯基体中的热降解行为及协同阻燃性;并用拉曼光谱和扫描电镜分析了残炭的结构和形貌,进一步研究了其协同阻燃机理.结果表明,NOR116/分子筛协效阻燃体系可明显提高极限氧指数并改善燃烧时熔滴缺陷,显著降低热释放速率、烟释放速率;NOR116可有效提高PP的初始分解温度及最大分解速率温度,使膨胀阻燃体系后期的交联成炭及气体释放更加匹配;在燃烧过程中分子筛与膨胀阻燃体系形成了Si-P-AI-C的结构,可有效稳定炭层;拉曼光谱及扫描电镜结果表明,NOR116和分子筛可促进膨胀阻燃体系形成致密且高石墨化程度的炭层,有效阻隔了氧气的进入及热的反馈.

关键词: 聚丙烯 , 膨胀阻燃体系 , 受阻胺 , 熔滴 , 分子筛 , 协同效应

RESIDUAL STRESS CONCENTRATION AND ITS EFFECTS ON FATIGUE LIMIT AND SHORT CRACK GROWTH

HE Jiawen HU Naisai ZHANG Dingquan Xi'an Jiaotong University , Xi'an , China Professor , Research Institute for Strength of Metals , Xi'an Jiaotong University , Xi'an 710049 , China

金属学报(英文版)

Residual stress concentration at a notch depends on both notch geometry and yield strength of the material.It varies through the depth,and its magnitude may be higher than the theoretical one.Compressive residual.stress concentration at the notch of shot-peened specimen of soft material is easily to he relaxed,with the surface damage during shot-peening results in a mi- nor contribution to the fatigue limit.Compressive residual stress increases the crack closure effect at the notch and may lead to a non-propagating crack.

关键词: residual stress , null , null

Ultrafine Grained HSLA Steels for Cold Forming

R González , J O García , M A Barbés , et al

钢铁研究学报(英文版)

This research shows, through the analysis of three steels that comply with the EN 10149-2 Euronorm, examples of ultrafine grained (or ultrafine ferrite) ferrous alloys, with ASTM grain sizes close to 14 (2 3 m). These steels are microalloyed with Ti-Nb and have been produced by advanced hot rolling controlled techniques in the factories of ArcelorMittal de Avilés (Asturias, Spain) and are mostly used in automotive and construction applications. By comparison, other techniques to obtain ultrafine grained steels are mentioned, though they have not yet reached the industrial level and are produced in laboratories due to the fact that their mechanical properties (low strain hardening coefficient "n") don't allow cold working operations such as bending, stretching nor drawing.

关键词: ultrafine steels;metallography;strain hardening;Euronorm

CRYSTAL STRUCTURE AND ELECTROCHEMICAL PROPERTIESOF Zr(Mn1-xNix)2(0.40≤x≤0.75) HYDROGEN STORAGE ALLOYS

W.K. Zhang , C.A. Ma , X.G. Yang

金属学报(英文版)

The crystal structure, phase abundance and the electrochemical properties ofZr(Mn1-xNix)2 (0.40≤x≤0.75) alloys were investigated by means of XRD, Rietveldrefinement method and electrochemical measurements. The alloys are multiphase.C15 Laves phase occurs as a main phase accompanying with C14 phase and other mi-nor phases, indicating that Ni element is C15-stabilized element for ZrMn2 alloy. Thephase abundance and lattice parameters of Laves phase are influenced significantly byNi substitution. The Zr(Mn0.45Ni0.55)2 alloy with the highest amount of C15 phaseexhibits the maximum electrochemical capacity of 242mAh/g. C14 phase occurring inZr-Mn-Ni alloys is beneficial for the electrochemical kinetics of hydride electrodes.

关键词: hydrogen storage alloy , null , null , null

INTERGRANULAR CORROSION AND PHOSPHOR SEGREGATION AT GRAIN BOUNDAR1FS OF NON-SENSITIZED SUPERPURE AUSTENITIC STAINLESS STEEL 00Cr25Ni22Mo2N

FANG Yaohua Nanjing Institute of Chemical Technology , Nanjing , ChinaXU Yuan ZHANG Wenqi University of Science and Technology Beijing , Beijing , China FANG Yaohua Associate Professor , Dept.of Applied Chemistry , Nanjing Institute of Chemical Technology , Nanjing 210009 , China

金属学报(英文版)

The corrosion behaviour and mechanism of superpure austenitic stainless steel 00Cr25Ni22Mo2N in urea processing environment was studied using metallography,SEM, TEM,SIMS and AES techniques.The results show that the gas extraction tube made of non-sensitized 00Cr25Ni22Mo2N steel suffered intergranular corrosion.Corrosive media penetrated not only into the tube wall through grain boundaries but also expanded from the boundary towards the interior of the grain.Neither depletion of Cr nor precipitates were found at the grain boundaries.However,P(and Si)was segregated at the grain boundaries to a great extent.Semiquantitative calculation indicates that the P content at the grain boundaries is about 25 wt-%,three orders of magnitude higher than the content within the grain.Sugges- tion is made that the potential difference between the grain and its boundary due to the segre- gation results in the observed intergranular corrosion.

关键词: superpure austenitic stainless steel , null , null