羟乙基与N-琥珀酰羟乙基壳聚糖的制备表征及细胞毒性试验

壳聚糖（chitosan,CTS）与氯乙醇反应制备羟乙基壳聚糖（hydroxyethyl chitosan,HECTS）,并接合琥珀酸酐合成N-琥珀酰羟乙基壳聚糖（N-succinyl-hydroxyethyl chitosan,Suc-HECTS）,考察琥珀酰化度的影响因素确定最适反应条件。用FT-IR对产物进行结构表征,1 H NMR测定脱乙酰度和琥珀酰化度,元素分析法测定羟乙基取代度,并评价了HECTS和Suc-HECTS的细胞毒性。结果表明HECTS与Suc-HECTS均无细胞毒性。在生物医药和药物载体方面的应用提供了一定的理论基础。     

N-羧甲基壳聚糖的合成改进及吸附性能

采用氯乙酸替代乙醛酸与壳聚糖反应,以Na2CO3为缚酸剂,合成了N-羧甲基壳聚糖,并采用红外光谱(FT-IR)、核磁共振(1H-NMR和13C-NMR)对其进行表征。考察了N-羧甲基壳聚糖对Ni2+的吸附性能,探讨了N-羧甲基壳聚糖的取代度、溶液初始pH值和吸附时间等因素对吸附量的影响。研究发现,羧甲基化发生在壳聚糖的氨基上。当产品的取代度为1.24时,最佳初始pH值为7,最佳吸附时间为2h,其吸附量为124.5mg/g。FT-IR表征说明羧基和Ni2+发生了配位反应。     

用于处理放射性废水的丙烯酰胺改性壳聚糖制备工艺研究

为获得吸附性能强的改性壳聚糖,采用丙烯酰胺自由基引发侧链接枝方法对壳聚糖进行改性,考察了引发剂种类、引发剂和壳聚糖质量比、丙烯酰胺和壳聚糖质量比、反应温度、反应时间、搅拌速率以及析出溶剂对改性壳聚糖产物收率及吸附性能的影响,在此基础上开展了正交试验和后续的验证实验。结果表明:在氮气保护、改性剂丙烯酰胺与壳聚糖质量比为7、引发剂硝酸铈铵与壳聚糖质量比为0.1、反应温度45℃、反应时间150min、搅拌速率400r/min条件下、在丙酮中析出并真空干燥的改性壳聚糖对Co~(2+)离子的吸附容量为16.42mg/g,较未改性前提高了约64.53%。     

聚乙烯醇/壳聚糖/明胶水凝胶的合成及其对苯酚的吸附研究

以聚乙烯醇(PVA)、壳聚糖和明胶为原料、戊二醛为交联剂,在酸性溶液中通过共混交联反应合成了聚乙烯醇/壳聚糖/明胶水凝胶,单因素法讨论了影响水凝胶性能的因素如:反应物质量比、交联剂用量、反应温度、反应时间等聚乙烯醇/壳聚糖/明胶水凝胶,对不同浓度苯酚溶液的吸附研究.研究结果表明聚乙烯醇/壳聚糖/明胶水凝胶对苯酚有较好的吸附性能.     

浅谈壳聚糖及壳聚糖膜

介绍了壳聚糖膜的成膜机理,以壳聚糖的结构和性质为基础,总结了壳聚糖膜的制备方法。其中关于化学改性方面主要介绍了酰化反应、烷基化反应、酯化改性、醚化反应、羧甲基化反应、季铵化反应等。用以下几种指标来表征壳聚糖膜的特征,包括机械性能、气体选择渗透性和阻湿性、润湿性能、抑菌性、可食用性与安全性等因素。最后,重点介绍了壳聚糖膜在果蔬保鲜方面的应用,为壳聚糖膜的发展指明了一定的方向。     

明胶-壳聚糖合金膜的制备及表征

采用水溶液共混法制备了明胶-壳聚糖合金膜,添加了醋酸氯己啶为抑菌剂,1-乙基-3-(3-二甲氨丙基)碳化二亚胺盐酸盐为交联剂.通过IR、DSC和UV对合金膜进行了表征,证明了明胶、壳聚糖和醋酸氯己啶在合金膜中有很好的相容性.研究了体系中醋酸氯己啶含量和交联剂用量对合金膜吸水率、溶胀比和孔隙率等性能的影响.结果表明,在实验范围内随醋酸氯己啶含量的增加,膜的吸水率和孔隙率逐渐下降,而溶胀比变化不大;随交联剂量增加,膜的孔隙率增大,而溶胀比和吸水率基本不变.抑菌实验表明,醋酸氯己啶的加入提高了膜的抑菌性能.     

壳聚糖改性地聚合物的力学及吸附性能

采用壳聚糖增韧改性矿渣基地聚合物,研究了壳聚糖掺量对矿渣基地聚合物强度与弯曲韧性、吸附重金属离子性能的影响规律,采用FTIR、NMR、SEM及EDS等测试手段揭示了壳聚糖对矿渣基地聚合物的改性机制。结果表明,与空白样相比,壳聚糖掺量（与矿粉质量比）为2%的矿渣基地聚合物28天弯曲韧性系数提高497.22%,对Pb2+、Cr3+的吸附效率分别提高68.89%、81.45%。壳聚糖在分子层面（C—O—Si键的形成及[SiO₄]聚合度的降低）及亚微观层面（三维互穿网络结构的形成）对矿渣基地聚合物进行增韧改性。壳聚糖自身较高的吸附性及低Ca/Si比C—S—H凝胶数量的增加,是矿渣基地聚合物吸附性能显著提升的关键。      

O-羧甲基壳聚糖的制备及其抗菌性能研究

在低温条件下使用氯乙酸对壳聚糖进行羧甲基化改性,并进一步研究反应条件对产物分子质量、取代度及抑菌效果的影响,同时以大肠杆菌为实验菌种,深入研究取代度与O-羧甲基壳聚糖抑菌性能之间的关系。结果表明:(1)-20℃下,壳聚糖在氢氧化钠溶液中浸泡6h,壳聚糖与氯乙酸的摩尔比为1∶1.4,然后50℃下反应3h,所得产物具有优良的抑菌性能,其抑菌率为92%,取代度为0.88;(2)将壳聚糖进行羧甲基化改性后,其抑菌效果得到进一步的提高,且取代度为0.8~0.9时,其对大肠杆菌的抑菌效果最好,抑菌率为87%~93%。     

磁性交联壳聚糖的制备及其对钍(Ⅳ)的吸附研究

以戊二醛为交联剂,将壳聚糖包裹在Fe3O4磁子表面制成磁性壳聚糖(MC)。考察了MC对钍的最佳吸附时间、最佳pH和初始浓度。结果表明:MC对钍有很好的吸附性能,最佳pH为5,浓度为60μg/mL时MC对钍的吸附在7 h达到平衡,吸附量达49.60 mg/g,去除率达90%以上。利用拟一级反应动力学模型和拟二级反应动力学模型对实验数据进行拟合,并分别采用Freundlich模型和Langmuir模型对吸附等温线进行拟合。     

新型壳聚糖交联改性物的制备及其性能研究

先将壳聚糖(CTS)与甲酰氯经过酰氯化反应后,其产物再与戊二醛发生交联反应,得到具有较好吸附性能的交联壳聚糖(CCTS)。研究结果表明:CTS与戊二醛的质量配合比为1∶1,反应温度为65℃,pH为5.0,反应时间为3h的条件下,制得的CCTS的交联度最高可达87.35%,在中性废水中对铅离子(Pb~(2+))的吸附量最大达到1.92mg/L。     

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.     

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.……     

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 ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.