交联透明质酸凝胶薄膜的制备及性能研究

用三偏磷酸钠(STMP)对透明质酸(HA)进行交联,制备出HA-STMP凝胶薄膜,研究了不同交联程度HA-STMP薄膜的吸水保水性能和体外降解性能。研究结果表明,实验中控制STMP与HA的结构单元比在1/5以上都可以得到成膜性能良好的交联薄膜;HA-STMP交联薄膜可以吸附自身质量7～10倍的水分,且随着交联程度的提高,薄膜的吸水能力下降,保水性能提高;交联改性能改善HA的耐降解性能,使高聚物在体内的存留时间延长,且耐降解性能随交联程度的增加而提高。     

氟化PVA-SiO2薄膜单面疏水性的研究与表征

目的 研究开发一种具有单面疏水性能的聚乙烯醇薄膜材料作为包装材料。方法 将质量分数为12%、醇解度为88%的PVA溶液与质量分数为5%的纳米SiO2溶液按体积比为1∶1混合并加热搅拌,通过流延干燥的方式制备PVA-SiO2薄膜。然后分别用体积分数为2.5%,5%,7.5%的十七氟癸基三甲氧基硅烷（FAS）-乙醇溶液以浸泡方式修饰薄膜的其中一面,并通过溶解性测试、接触角测试、场发射扫描电子显微镜（FE-SEM）、傅里叶变换衰减全反射红外光谱测试（ATR-FTIR）等方法表征改性结果。结果 结果表明薄膜单面疏水性得到改善,改性后的薄膜在水中的溶解时间增加,且接触角均在120°以上,表明FAS起到了降低表面能的作用;FE-SEM结果显示,Si元素含量对薄膜的疏水性能有着重要影响;ATR-FTIR显示,FAS改性成功将氟原子引入到薄膜表面,且增加了硅原子的数量。其中用质量分数为5%的FAS-乙醇溶液修饰后的薄膜疏水性最好,接触角达到了126.21°。结论 与未改性薄膜相比,经FAS单面疏水改性的PVA-SiO2薄膜疏水性能得到大大提高,拓宽了PVA薄膜材料的应用领域。     

透明质酸水凝胶的制备与评价

透明质酸(HA)被广泛地用于生物医药领域。以1-乙基-3-(3-二甲基氨丙基)-碳化二亚胺/N-羟基丁二酰亚胺(EDC/NHS)催化HA与己二酸二酰肼(ADH)反应,制备化学交联的HA水凝胶。通过扫描电镜和红外光谱来测定HA与HA水凝胶的结构,测量HA水凝胶在模拟胃肠液中的溶胀率,并以牛血清白蛋白(BSA)为模型药物,初步探讨了HA水凝胶体系的释药行为。实验结果显示:HA水凝胶由酰胺键生成三维网络结构且网络孔径较大,具有较好的吸水性能。该水凝胶制备过程简单,反应迅速,条件温和,属酸敏突释释药体系。     

电纺丝法制备纳米纤维薄膜的降解性能研究

电纺丝法制备了PLLA、PLGA、PLLA/PLA-PEG、PLLA/HA纳米纤维薄膜,用SEM表征了纳米纤维的形貌.在37℃,pH值为7.4的PBS溶液中对4种纳米纤维薄膜的降解性能进行研究,通过GPC测试降解过程中聚合物分子量的变化,SEM表征降解过程中纳米纤维形貌的变化.结果表明:PLGA薄膜降解速率较快,吸水率最高;PLLA/PLA-PEG次之;PLLA降解速率较慢,吸水率最低,HA的加入可调节PLLA的降解速率.     

可降解聚乳酸/羟基磷灰石杂化材料--Ⅱ.聚乳酸/羟基磷灰石杂化材料的制备及降解

采用超声分散技术,以聚（D,L）-乳酸（PDLLA）和纳米羟基磷灰石（HA）为原料,制备出PDLLA／HA杂化材料。研究了PDLLA／HA杂化材料在生理盐水中的降解性能,并对相关产物进行了FT-IR、TEM、XRD分析．结果表明,杂化材料中PDLLA与HA间通过氢键结合,随着HA含量的增加,杂化材料在生理盐水中的降解速率减缓,此外,杂化材料的降解包括PDLLA的降解和HA的重新沉积钙化两个过程。降解12周后,HA的晶体结构被破坏,重新沉积钙化形成多孔骨骼结构。     

不同温度下氮化铬薄膜的疏水性能研究

利用电弧离子镀膜技术,以硅片、不锈钢、玻璃片为基底,在脉冲偏压分别为50 V、100 V、150 V的条件下制备了三组氮化铬薄膜样品,对其物相、表面形貌、力学性能及不同温度下的疏水性能进行了分析研究。结果表明：所制备薄膜样品组分单一,表面存在些许“大颗粒”,当脉冲偏压为100 V时“大颗粒”数量最多;氮化铬薄膜力学性能优良,150 V脉冲偏压下沉积的薄膜具有较高的硬度和杨氏模量,50 V脉冲偏压样品具有较高的膜基结合力;常温（20℃）下薄膜疏水性均较好,基底材料对疏水性能影响不大;各组薄膜疏水性能随环境温度的增加而降低,当环境温度上升至80℃时脉冲偏压为50 V的薄膜丧失疏水性能,脉冲偏压为100 V的薄膜样品疏水性能整体较优。     

离子束技术沉积羟基磷灰石薄膜的结构及溶解性能

分别采用离子束溅射和离子束增强沉积技术,以烧结羟基磷灰石（HA）陶瓷为靶材,在纯钛金属基片表面沉积HA薄膜．X光电子能谱分析表明：薄膜中Ca、P、O元素的化学态与所用HA陶瓷靶材相接近;相比HA靶材,薄膜表面存在CO₃^2-．X射线衍射分析表明：沉积薄膜均为非晶态结构,经650℃退火处理转变为结晶磷灰石．在模拟体液中的溶解实验揭示：薄膜仅与溶液中Ca、P和O存在离子交换;薄膜易降解,浸泡10天,样品经历了降解、再沉积过程;相比离子束溅射沉积膜,离子束增强沉积膜具有加速沉积Ca、P的能力．     

聚乳酸改性研究及其在包装领域的应用

聚乳酸（polylactideacid，简称PLA）是一种合成高分子聚合物。可以完全生物降解，不论是PLA本身还是其降解产物都对人体无毒无害、对环境无污染、符合低碳环保的要求，同时，PLA不但具有良好的物理机械性能、透明度、光泽度、刚性、耐油性、气味阻隔性、加工性、一定的抑菌和抗霉性、一定的热学性能和不会自行恢复的折叠性。而且具有与传统薄膜相类似的印刷性能，根据这些性能可以将PLA材料加工成薄膜、瓶、管等包装容器，从而将PLA应用于水果保鲜包装、奶酪产品包装、食品抗菌包装、药品包装等领域。     

淀粉/PVA膜在血浆模拟液及唾液模拟液中的体外降解行为及相关体外生物相容性评价

通过熔融浇注法制备出一系列厚度在0.05 mm～0.10 mm的淀粉/聚乙烯醇（PVA）（SP）薄膜。研究了薄膜在血浆（SBF）及唾液模拟液（SSF）中的降解行为,分析了降解过程中力学性能、失重率、溶胀度、热性能以及表面形态的变化。研究结果表明,膜在30天的降解过程中能够维持良好的尺寸稳定性和一定的力学强度。通过细胞毒性、细胞贴壁及溶血试验表征了膜的体外生物相容性。结果表明,SP膜具有良好的细胞和血液相容性。所有测试结果证明,SP薄膜是一种应用于诱导组织再生薄膜的潜在材料。      

玻璃表面超疏水性薄膜制备

采用溶胶-凝胶法,以三甲基氯硅烷、氢氟硅酸和水为先驱体,在玻璃基片上用提拉法制备出一种含有-CF3强疏水性基团的氟硅烷薄膜.通过红外光谱和扫描电镜对薄膜结构和表面形貌进行了表征和观察.并用接触角测定仪三甲基氯硅烷和氢氟硅酸在不同摩尔配比下薄膜疏水性能.结果表明该薄膜具有高度交联的不规则球状表面结构.当三甲基氯硅烷和氢氟硅酸的摩尔比为2.5:1时,薄膜具有超疏水性,对水滴的表面接触角可达156°.     

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.