手性分子结构对嵌段共聚物自组装螺旋的影响

手性小分子诱导嵌段共聚物手性组装是构筑手性可控螺旋结构的一种有效方法,但是目前对手性小分子引导螺旋结构形成的机制还没有明确认识。文中利用具有不同化学结构的手性掺杂剂与聚1,4-丁二烯-b-聚环氧乙烷(PBd-b-PEO)共组装,研究了手性小分子化学结构的差异对螺旋结构形成的影响。通过小角散射、透射电镜和圆二色光谱证明了苹果酸和扁桃酸诱导嵌段共聚物中PEO形成螺旋相结构,而酒石酸二苄酯和二乙酰基酒石酸由于氢键位点和取代基效应无法诱导形成螺旋相结构。组装体由于聚合物结构变化和手性分子聚集态变化而呈现不同的手性信号变化规律。通过分子模拟分析了共组装体系中氢键缔合体的稳定性,从能量角度解释了手性分子结构对聚合物形成螺旋结构的影响。     

替考拉宁手性膜拆分对羟基苯甘氨酸的研究

以聚砜膜为基膜,大环抗生素替考拉宁作为手性选择剂,1,6-己二异腈酸酯为交联剂,采用界面聚合法,制备具有手性选择性的替考拉宁-异腈酸酯聚砜复合膜。研究优化了单体摩尔比、聚合反应时间等制膜条件,渗析分离了D,L-对羟基苯甘氨酸.当D,L-对羟基苯甘氨酸的料液浓度为0.1mg/mL时,其对映体过剩值(e.e.)可达90.5%.     

膜拆分法分离制备手性药物

手性是自然界的一种普遍现象,天然存在的手性化合物很多,构成生物体的基本物质如氨基酸、糖类和蛋白质等也都是手性分子.外消旋体药物的手性拆分目前在单一手性药物的制备上仍占有极其重要的地位.手性拆分膜包括基于对映体间亲和性差异的固体膜和基于选择性萃取的液膜两大类.膜分离技术具有能耗低、易于连续操作等优点,被普遍认为是进行大规模手性拆分非常有潜力的方法之一,具有良好的应用前景.手性拆分膜技术引起了国内外研究者们的广泛关注,并成为膜学界研究的新热点.     

聚丙烯中空纤维膜/二(2-乙基已基)膦酸体系萃取水溶液中铜离子的研究

研究了聚丙烯中空纤维膜接触萃取器中二(2-乙基已基)磷酸萃取金属铜离子的工艺条件以及溶剂夹带,分析了原料的pH值、两相流速、有机相初始铜离子浓度以及萃取膜面积对萃取效率的影响,结果表明,两相流速、萃取膜面积对萃取率基本无影响,而水溶液的pH值和有机相初始铜离子浓度的改变使萃取率在40%～99%之间变化.这主要是由于整个萃取过程的传质阻力主要来源于D2EHPA和Cu2 的界面配位络合反应阻力,当铜浓度比较高时,传质阻力或传质系数与铜浓度无关,其值基本不变;而当铜浓度降低时,传质阻力随着铜浓度的降低而增大,传质系数则随着铜浓度的降低而减小.     

Cu（Ⅱ）席夫碱配合物催化硫醚不对称氧化反应研究

席夫碱（Schiff base）配合物不对称催化氧化硫醚是获得手性亚砜的有效途径之一。该文利用2, 4-二羟基苯乙酮缩-乙二胺席夫碱配体（H2L）通过水热法合成了Cu（Ⅱ）配合物（CuL）;利用质谱、元素分析以及单晶衍射等分析手段对配合物进行表征;利用紫外-可见光谱法研究了Cu L与牛血清白蛋白（BSA）的相互作用;探究了在存在牛血清白蛋白（BSA）的情况下,CuL在水溶液中对硫醚不对称氧化的催化活性和对映体选择性。在叔丁基过氧化氢（TBHP）为氧化剂、pH值为5的条件下,CuL催化甲基苄基硫醚获得了的较高的转化率（91.79%）和完美的化学选择性（100%）,而对映体选择性较低（26.80%）。     

TOMAC/正辛醇/异辛烷反胶团体系

研究了用三辛基甲基氯化铵(TOMAC)/正辛醇/异辛烷反胶团相转移法萃取细胞色素C时,水相pH值、离子强度、正辛醇含量、相体积比、搅拌时间等因素的影响.结果表明,正辛醇的量、水相pH值是萃取过程的关键因素,在低离子强度(CKCl＝0.05*!mol/L)、高pH值(pH＝13.66)、含正辛醇体积分数为0.85%的情况下,萃取率接近100%.     

液膜法萃取青霉素的研究

介绍了乳状液膜法萃取模拟发酵液中青素的研究工作，考究了混合槽中液膜组成、试剂比、油内比、乳水比及外水相ＰＨ变化对传质过程的影响，找出了一个较为适宜的液膜组成及室浊下适宜操作的萃取工艺条件。     

Sol-gel法制备铈酸钡纳米粉末

以硝酸钡和硝酸铈为原料,以硝酸铵为助燃剂,以柠檬酸和乙二胺四乙酸为螯合剂,采用溶胶-凝胶法制备BaCeO3纳米粉末.通过TG-DTA和XRD分析前驱体在升温过程中的物相变化,通过SEM研究样品形貌.结果表明,煅烧温度和时间对铈酸钡单相的形成有重要影响;溶液的pH值和硝酸铵浓度对产物样品粒径尺寸和分散度有一定的影响.     

色氨酸在自制牛血清白蛋白手性柱上的拆分

利用三氯聚氰活化的氨丙基硅胶与牛血清白蛋白反应,快速而经济地制得牛血清白蛋白手性固定相。在反相模式下,将该手性固定相用于色氨酸的拆分,系统探讨了流动相pH值、柱温、有机修饰剂的种类及含量等对手性拆分的影响。色氨酸在自制牛血清白蛋白手性柱上得到了理想的拆分,分离因子可达4.33。     

TOMAC／正辛醇／异辛烷反胶团体系萃取细胞色素C

研究了用三辛基甲基氯化铵（TOMAC）／正辛醇／异辛烷反胶团相转移法萃取细胞色素C时,水相pH值、离子强度、正辛醇含量、相体积比、搅拌时间等因素的影响。结果表明,正辛醇的量、水相pH值是萃取过程的关键因素,在低离子强度（CKCl＝0．05mol/L）、高pH值（pH＝13．66）、含正辛醇体积分数为0．85％的情况下,萃取率接近100％。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...