含芴星形聚合物的合成与包合

本文合成了苯乙烯基-p-聚(9,9-二己基芴)(PFS)大单体,以β-环糊精(β-CD)为核,通过ATRP方法将PFS单体与甲基丙烯酸-N,N-二甲氨基乙酯(DMAEMA)无规共聚,得到了星形发光聚合物β-CD-g-P(PFS-r-DMAEMA)21,通过氢核磁共振谱和凝胶渗透色谱对其结构进行了表征,并将其用于包合客体分子苝,通过紫外-荧光测试表征了主客体分子的包合性能,发现了聚合物与客体分子间的能量传递现象,通过计算机分峰拟合得到两者各自的发光比。     

基于β-环糊精自组装的氧化还原敏感超分子凝胶

分别合成了多酸EMPOL-1016分子链末端携带β-环糊精的主体分子(EM-βCD)和聚乙烯亚胺(600)分子链末端携带二茂铁的客体分子(PEI-Fc),并用核磁共振对PEI-Fc和EM-βCD的结构和组成进行了表征。研究表明,PEI-Fc和EM-βCD由于β-CD基团与Fc基团之间的主客体包合作用自组装形成超分子凝胶。由于β-CD-Fc之间的包结具有氧化还原性,PEI-Fc/EM-βCD凝胶可在氧化剂存在时呈溶胶状态,被还原时重新形成凝胶。     

利用主客体识别构建的树状超分子

树枝状大分子具有高度支化和规整的特殊结构,在生物医药、催化化学等多个领域深具发展前景,但目前其制备均采用化学合成方法。文中发展了一种利用自组装手段构筑树枝状大分子的新方法。通过中心分子4臂-聚乙二醇-金刚烷(4 arm-PEG-Ad)和迭代单元β-环糊精-肉桂(β-CD-Ci)以及α-环糊精-己二胺-金刚烷(α-CD-hex-Ad)之间的主客体识别,在水体系中,逐步组装得到超分子树状聚合物。通过动态光散射及透射电镜发现,随着代数增长,超分子树状聚合物在溶液中粒径逐渐变大。由于环糊精与客体基团可响应温度变化产生解包合,这种树状超分子结构在温度上升到60℃以上时会发生瓦解,超分子树状聚合物的粒径由最初的单分散性变为多分散性。     

新型环境敏感性β-环糊精水凝胶的合成及性能研究

通过单6-对甲基苯磺酰β-环糊精酯(β-CD-6-OTs)与乙二胺反应引入活泼的氨基后,进一步与丙烯酸作用进行酰胺化反应,得到单乙烯基修饰β-环糊精(β-CD-6-EA),并以此为单体在交联剂N,N′-亚甲基双(丙烯酰胺)存在下,分别与丙烯酸和甲基丙烯酸-N,N-二甲氨基乙酯共聚,合成两类分子中含悬挂式β-环糊精结构的水凝胶(CEA和CED).通过红外光谱表征了水凝胶的结构,溶胀实验结果表明该水凝胶具有较好的pH,温度及离子强度敏感性.     

温敏水凝胶对疏水性药物的装载及释放行为

聚己内酯-聚乙二醇-聚己内酯(PCL-PEG-PCL)三嵌段共聚物的水溶液,具有低临界溶液温度(LCST),可制备温敏水凝胶,并可作为药物载体应用于生物医学领域。 使用 β-环糊精衍生物作为分子胶囊,在改善疏水性药物的水溶性的同时,提高 PCL-PEG-PCL 水凝胶对疏水性药物的装载和释放能力。 实验中槲皮素作为疏水性药物的模型,由于槲皮素分子与 β-环糊精络合形成微胶囊包装结构,大幅度提高了槲皮素的溶解度;此外槲皮素 / β-环糊精衍生物水溶液中 PCL-PEG-PCL 三嵌段聚合物,也快速溶解形成共混溶液,当温度提高到体温时,迅速变成凝胶状态。 在缓冲溶液中进行了槲皮素药物的释放实验,实现了 PCL-PEG-PCL 水凝胶对疏水性药物的缓释效果,在缓释过程中 β-环糊精衍生物也充当了药物释放载体的作用。     

环糊精衍生物水凝胶材料的研究进展

水凝胶是一种由化学或物理交联的高分子聚合材料,具有亲水性的三维网络结构,使其能够吸收并保持大量的水分。水凝胶相对其他材料有着明显优势,其具有含水量高、性质柔软、通透性高、生物相容性好等优点,这些优异的性质使水凝胶在工业、农业、生物医学乃至生活中都有着广泛的应用。近些年来国内外研究者都致力于开发新型水凝胶,以解决传统水凝胶存在的力学强度差、功能单一的问题。因此,涌现了大批多功能、高强度的新型水凝胶,如温度、pH、光、电磁刺激响应性水凝胶,双网络、互穿网络水凝胶,纳米复合水凝胶,自愈合性水凝胶。其中,环糊精及其衍生物的引入是改善水凝胶不足的重要方法之一。环糊精存在特殊的外缘亲水、内部疏水的环状分子结构以及疏水性空腔,能够通过主客体偶合作用稳定络合疏水性分子。近年来,研究者们充分利用环糊精独特的结构和性质,在设计更好的环糊精衍生物水凝胶结构和功能方面不断地进行尝试,取得了丰硕的研究成果,制备了一系列具有优异性能的环糊精及其衍生物高分子水凝胶。环糊精及其衍生物水凝胶不仅在力学性能方面表现出优势,还具有显著的功能性,如刺激响应性、自修复性、形状记忆性、可注射性等。目前,已报道的环糊精衍生物水凝胶结构多样、性质各异,按其网络结构可分为:(1)化学修饰环糊精作为交联剂合成水凝胶;(2)环糊精衍生物的主客体超分子水凝胶;(3)环糊精衍生物的物理/化学双交联水凝胶;(4)环糊精衍生物的滑环水凝胶。各种交联结构的环糊精衍生物水凝胶的开发,赋予了水凝胶不同的功能和性质,为突破传统水凝胶的应用瓶颈提供了思路,使其在催化工程、药物控释、骨/软骨组织修复和水污染物净化领域具有广阔的应用前景。本文归纳了环糊精衍生物高分子水凝胶的研究进展,按水凝胶的交联结构对环糊精衍生物水凝胶进行分类,分别对环糊精分子、环糊精衍生物水凝胶的结构、制备方法、应用等进行介绍,分析了环糊精衍生物高分子水凝胶所面临的问题并展望其前景,以期为制备多功能、高强度环糊精衍生物水凝胶提供参考。     

主客体胶束水凝胶的制备及对神经生长因子的包载

通过可逆加成-断裂链转移聚合(RAFT)反应制备了一种亲水性两嵌段聚合物——聚乙二醇/聚N-异丙基丙烯酰胺(PEG-PNIPAM),利用α-环糊精(α-CD)与其中PEG链段的选择性包合形成了一种独特的主客体胶束,这种胶束由于具备中空结构,可对亲水性药物起到很好的负载作用。其对神经生长因子的包载率为经典普朗尼克F127胶束的2倍。进一步利用主客体胶束为大分子交联剂制备丙烯酰胺水凝胶,可赋予水凝胶优异的力学性能,拉伸伸长率为化学交联对照组5倍,并且强度高于对照组2倍以上。循环拉伸测试表明,该水凝胶具有良好的应力耗散机制。     

聚吡咯/环糊精准聚轮烷分子导线材料的合成

在掺杂了α-环糊精或β-环糊精的情况下,对吡咯单体进行氧化聚合,制备了聚吡咯/环糊精准聚轮烷结构材料。通过傅里叶转换红外光谱、广角X射线衍射、元素分析、扫描电镜、电导率测试和循环伏安曲线等手段,表征了聚吡咯/环糊精准聚轮烷的微观结构与微观形态,研究了其导电性能。结果表明,准聚轮烷中吡咯单元和α-CD、β-CD分子的比值分别约为5∶1和24∶1。与聚吡咯相比,准聚轮烷的电导率明显降低,氧化还原的可逆性也有所降低。这类材料在分子导线领域具有广阔的应用前景。     

基于F127的原子转移自由基超分子水凝胶的制备及性能

由α-环糊精或2-溴异丁酰溴改性的α-环糊精与溴丙酰溴封端的F127自组装形成的聚准轮烷(PPRs)为大分子引发剂,通过原子转移自由基聚合(ATRP),以聚乙二醇二丙烯酸酯(PEGDA)为桥键单元,2-甲基丙烯酸羟乙酯(HEMA)为调节剂制备了交联网络可调的热敏性超分子结构水凝胶。红外光谱(FT-IR)、核磁共振(1H-NMR)和X射线衍射(WAXD)对改性和包合物进行了表征。引入α-环糊精降低了凝胶溶胀度,而改性α-环糊精体系可以提高溶胀度。随PEGDA含量的增加,凝胶溶胀度提高,但随HEMA含量增加而降低。在20℃~50℃范围内,引入聚甲基丙烯酸羟乙酯链降低了凝胶的温度响应性,而由改性α-环糊精线穿的PPRs制备的水凝胶显示最好的热敏性和良好的力学强度。水凝胶的热敏性机理是由于共聚物中PPO链段的聚集形成。     

具有pH值敏感的磁性β-环糊精微球的制备与性能

采用反相乳液聚合法,由改性磁性Fe3 O4纳米粒子、β-环糊精(β-CD)、丁二酸酐(SA)制备了具有pH值敏感的β-环糊精磁性微球;通过红外光谱、透射电镜对微球进行了结构表征和形貌观察,并探讨了微球的pH值敏感性和磁响应性能.结果表明:制备的β-CD微球为核壳结构,粒径为20μm左右,具有良好的磁性和pH值敏感性.     

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 ...