FORMATION OF PRECIPITATED AUSTENITE IN 9%Ni STEEL AND ITS PERFORMANCE AT CRYOGENIC TEMPERATURE

The formation of precipitated austenite in 9% Ni steel exposed at the temperature of α+γ re-gion and its influence on impact tonghness at cryogenic temperature have been studied.Austenite-rich and ferrite-rich bands are formed during soaking because of the re-distribu-tion of elements of C,N and Ni.The former phase is enriched of Ni,Mn,C and N,while thelatter one is relatively pure.Part of the austenite formed at intermediate temperatures trans-forms into martensite when the steel is cooled down to room temperature.The complex struc-ture which consists of fine martensite and austenite exhibits a moderate strength and highenough cryogenic toughness.The austenite enriched of C,N and Ni is still stable at thecryogenic temperature.The tearing ridges on the impact fracture surface is densely occupiedby the precipitated austenite,elongated along the tearing direction.One of the importantcause of the excellent eryogenic properties is that the precipitated austenite absorbs theimpurities and thus purifies the matrix of the steel.     

BAUSCHINGER EFFECT AND DISLOCATION STRUCTURE IN STAINLESS STEEL DURING CYCLIC DEFORMATION

Cyclic deformation in symmetrical push-pull mode was carried out at room temperature in airusing a Schenck hydropuls machine.The total strain amplitude which was kept constant dur-ing the test ranged from ±0.004 to±0.012.The 0.2% offset yield stress σ_(0.2f) in tensionand σ_(0.2r) in compression and peak stress σ were measured from the stress-strain hysteresisloop at various cycles.The Bauschinger strenghth differential factor(BSDF)was then calcu-lated from σ_(0.2f) and σ_(0.2r).The energy loss △E of each cycle was determined fromhysteresis loop areas.These parameters,BSDF,σ and △E,appear to have two distinctivelydifferent stages.The dislocation structures were observed using TEM in specimens deformed cyclically,forvarious cycles.The observation shows that the dislocations pile-up mainly against grainboundaries and there exist large amount of deformation twins.The addition of 0.25 wt-% ni-trogen reduced the stacking fault energy of the alloy significantly.Cross-slip and climb aretherefore rather difficult to occur during the cyclic deformation at room temperature,andwell-defined dislocation cells and walls can only be seen at the final stage of fatigue.     

EFFECT OF OXYGEN CONTENTS ON OXYGEN POTENTIALS OF H_2O-H_2 AND H_2O-H_2-INERTS GAS MIXTURES

By taking the effect of oxygen contents into account,a new set of formulae which representsthe oxygen potentials of H_2O-H_2 and H_2O-H_2-inerts gas mixtures has been derived.Classi-cal representation is only a particular case of it.Some of the variables affecting equilibriumatmosphere when trace oxygen is present and optimum preparation of the gas mixtures to min-imize errors have been discussed.The reliability of some of previous equilibrium experimentsunder the oxygen potentials controlled by H_2O-H_2 or H_2O-H_2-inerts gas mixtures has alsobeen criticized.     

北京糖果俱乐部改造设计

自2006年创立之始,阿克雅建筑师事务所就积极探索室内设计和建筑外观改造的创新。北京糖果俱乐部的改造是事务所在中国完成的一个富有意义的项目。     

高雄市立凤林国中新校区校舍

<正>凤林国中位于高雄市偏远的海角,隔着林园工业区有若工业沙漠中的一片绿洲。随着红毛港的开发,外海路经过旧校区而迁校。凤林小区被工业区隔离,小区缺乏文教公共设施,因而学校不只扮演教育场所,亦是小区文化、体育、休憩的场所。     

Mo的表面脉冲激光氮化

激光脉冲辐照置于氮气中的Ｍｏ使表面形成含γ－Ｍｏ２Ｎ的氮化层，激光使Ｍｏ表面熔化导致液相氮化反应，用ＳＥＭ、ＸＲＤ和ＡＵＧＥＲ谱分析表征了氮化层，激光在表层相起的加热和激波效应还有使表层微观组织致密的作用。     

Optimization of red blood cell inventory: a blood-type compatibility-preference and emergency model

Transfusion of red blood cells (RBCs) is essential for different medical conditions such as surgery, anemia, and cancer. Blood is a precious living composition consisting of eight types of RBCs that can be transfused by either exact or compatible substitutes. As stored blood gets older, it begins to deteriorate; therefore, excessive blood supply at hospitals results in spoilage, while limited supply results in shortage. This research aims at finding the optimal order-up-to-level quantities of blood, which minimize its shortage and outdated units. Stochastic demand, blood aging, emergency orders, and compatibility preference are considered in this study. A customized simulated annealing algorithm is built for optimization. Several simulation experiments are conducted to test the merits of the model in a selected hospital. Not only does the model demonstrate improved results in the mean inventory/age, shortage/spoilage, and substitution percentage but it also serves as a test bed for better understanding of RBC inventory behavior under different compatibility policies.     

Separation of Mixtures of Rutin and Quercetin: Evaluating the Productivity of Preparative Chromatography

The flavonoid rutin is present in significant amounts in the flower buds of Sophora japonica L. It offers numerous desired pharmacological effects. Under certain extraction conditions quercetin is found as a hydrolysis product which needs to be separated from rutin. This paper describes the application of liquid chromatography to solve this task. Based on the determination of adsorption equilibrium constants and column efficiencies, the productivity of the separation process is estimated, and scale-up considerations are presented. A comparison with alternatively directly crystallizing rutin from raw extracts is also reported.