Oil and fat hydrolysis with lipase fromAspergillus sp.

Hydrolysis of olive oil, soybean oil, mink fat, lard, palm oil, coconut oil, and a hydrogenated, hardened oil with lipase from anAspergillus sp. has been studied. The lipase had high specific activity (60,000 U/g) and did not show any positional specificity. The lipase proved to be a more effective catalyst than Lipolase fromA. oryzae, with an optimal activity at 37°C and pH 6.5–7.0. It was activated by Ca²⁺ but inactivated by organic solvents such as isopropanol and propanone. All substrates examined could be hydrolyzed to corresponding fatty acids with this enzyme at concentrations of 5–30 U/meq with yields of 90–99% in 2–24 h. The degree of hydrolysis was almost logarithmically linear with reaction time and occurred in two stages. The lipase was stable and could be repeatedly recycled for hydrolysis.     

纳米载体铜基催化剂对低碳醇合成的影响

本文用沉积-沉淀法制备了新型纳米载体低碳醇合成催化剂，并与共沉淀法所制备的催化剂进行了对比，结果表明，纳米载体催化剂活性高、耐热性能好、醇收率高纳米载体对纳米载体催化剂活性大小的影响顺序为：纳米Al2O3＞纳米ZnO-ZnAl2O4＞纳米MgAl2O4＞纳米MgO.工艺参数对反应性能的影响结果表明，反应温度低，甲醇选择性高；但温度太高（＞320℃）CO2。选择性升高，且整个反应为动力学控制；压力升高可提高活性和C1-C2OH选择性，但C4OH选择性下降；结合空速对产物分布的影响，反应可能按Smith和Anderson的缩聚机理进行．     

分散染料在涤/锦双组分纤维上色差的色度学分析

将涤 /锦复合丝分离成单一组分的超细涤纶和锦纶。用常用的分散染料同浴染色后 ,测定了各染色样品的颜色三刺激值 ,并经过色度学计算。实验分析表明 ,分散染料对锦纶染色物的反射光主波长值较相应涤纶染色物向长波方向移动 ;蒽醌类分散染料在锦纶上的得色量较小 ,彩度较低 ;而偶氮类分散染料对涤 /锦染色的总色差较小 ,较适合于涤 /锦复合丝的染色。     

Shape‐memory polyurethane/multiwalled carbon nanotube fibers

Shape‐memory polyurethane/multiwalled carbon nanotube (SMP–MWNT) composites with various multiwalled carbon nanotube (MWNT) contents were synthesized, and the corresponding SMP–MWNT fibers were prepared by melt spinning. The influence of the MWNT content on the spinnability, fracture morphology, thermal and mechanical properties, and shape‐memory behavior of the shape‐memory polymer was studied. The spinning ability of SMP–MWNTs decreased significantly with increasing MWNT content. When the MWNT content reached 8.0 wt %, the fibers could not be produced because of the poor rheological properties of the composites. The melt‐blending, extrusion, and melt‐spinning processes for the shape‐memory fiber (SMF), particularly at low MWNT contents, caused the nanotubes to distribute homogeneously and preferentially align along the drawing direction of the SMF. The crystallization in the SMF was promoted at low MWNT contents because it acted as a nucleation agent. At high MWNT contents, however, the crystallization was hindered because the movement of the polyurethane chains was restricted. The homogeneously distributed and aligned MWNTs preserved the SMF with high tenacity and initial modulus. The recovery ratio and recovery force were also improved because the MWNTs helped to store the internal elastic energy during stretching and fixing. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Temperature and catalyst effects on the production of amorphous carbon nanotubes by a modified arc discharge

Large amounts of amorphous carbon nanotubes (ACNTs) were prepared with Co-Ni alloy powders as catalyst in hydrogen gas atmosphere by a modified arc discharging furnace which can control temperature during the electric arcing process. The experimental results indicate that the cooperative function of temperature and catalyst plays an important role in the soot production rate and the relative ACNT purity. When temperature increases from 25 °C to 700 °C, the soot production rate increases from around 1 g/h to 8 g/h, the best relative ACNT purity at 600 °C can reach up to 99% compared to the room temperature sample. Without catalyst, only plate graphite is formed at 25 °C and very few carbon nanotubes are found when temperature increases to 600 °C. TEM, SEM, HRTEM and XRD analysis showed that the as-prepared carbon nanotubes are almost amorphous. The soot production rate is 8 g/h and diameter range of amorphous carbon nanotubes is about 7-20 nm, respectively.     

IT治理与站点内容战略控制机制研究

信息可以改变竞争环境的本质与结构,作为现代信息媒介的网站则可作为一种战略工具。会计准则制定者与监管者鼓励企业在其治理机制中植入以互联网为基础的信息披露政策,但关于站点信息披露的战略控制知识还不完善。描述了IT治理因素及其与网站信息披露相关的战略控制机制,并评估这些因素与机制之间的内在关系,给出了一个基于IT治理、战略管理与基于网站的公司报告文化的概念框架。     

社会阶层分化下高校思想政治教育的路径选择

我国社会阶层分化对高校思想政治教育产生了积极和消极的影响,在这种背景下,高校应调整思想政治教育的思路,加强情感教育、加强教育的层次性和提倡渗透式教育,切实提高思想政治教育的实效性。     

试论科技发展中的伦理向度

对于科技发展带来的一些消极影响,有人认为伦理的干预是无济于事的,甚至最终会影响科技本身的发展。但是,现实中科技与社会发展之间的密切关系表明,对科技的发展给予伦理导向是社会发展的必然走向。把科学发展观作为科技发展的伦理向度,能够实现科技发展和社会进步两者的双赢。     

语境在语言理解中的作用

语境在语言理解中起着重要作用,是语言交际的基础。结合具体例子,分析了语境在语言理解中具有消除歧义、转变语义、补充语言省略意义、帮助理解言外之意的作用。指出只有正确地把握语境,才能深入理解语言的真正含义。