甲苯与甲醇侧链烷基化合成苯乙烯KX催化剂失活现象的研究

考察了甲苯、甲醇侧链烷基化反应KX催化剂的稳定性及失活现象。并采用XRD、N2物理吸附、DTG、SEM、NH3-TPD、CO2-TPD和ICP等方法对反应前后的催化剂进行了表征。结果表明,反应前后活性位变化和积炭不明显,对催化剂失活影响很小。随着反应时间延长,反应过程中产生大量的水导致分子筛骨架脱铝,晶体结构被严重破坏,这是催化剂失活的主要原因。增强催化剂骨架的水热稳定性是解决催化剂失活问题的关键。     

Production of angiotensin-converting enzyme inhibitory peptides in Iranian ultrafiltered white cheese prepared with Lactobacillus brevis KX572382

In this study, ultrafiltered (UF) Iranian white cheese made with adjunct cultures including six Lactobacillus isolates (Lactobacillus brevis, L. casei and L. plantarum) from traditional Iranian Motal cheese. The peptide extract (<5 kDa) of cheese samples were assessed for angiotensin-converting enzyme (ACE)-inhibitory activity during ripening (5 °C). Among the strains used, L. brevis KX572382 (M8) was selected because of the greater increase in (ACE)-inhibitory activity in the cheese (P < 0.05). The highest activity of M8 extract was observed on the 28th (71.72%) day of ripening (P < 0.05). Proteolytic activity assessment and RP-HPLC peptide profile of M8 water-soluble extracts (WSEs) indicated the effect of M8 on further protein degradation due to secondary proteolysis. A total of 7 different peptide sequences, previously known in the literature for their ACE-inhibitory activity, were tentatively identified by LC/ESI-MS in 28-day M8 peptide extract. Although the effect of M8 on pH and the proteolysis development in cheese was significant, no adverse effect was observed on the sensory properties. In conclusion, M8 strain can enhance the functional properties of Iranian UF white cheese.     

胎压监测系统的实现

轮胎压力监测系统对轮胎的压力进行实时的监测,提供异常状态下的报警信息,有极高的实用价值。本文给出了轮胎压力监测系统的实现过程,并针对其作为应用瓶颈的功耗问题,给出算法程序上的改进。并且,对于多个轮胎发射端发射所造成的冲突的避免,进行了算法讨论。     

空间KX型圆管相贯节点承载力的有限元分析

空间KX型圆管相贯节点常出现在主次桁架相交或连接面外支撑的节点部位,是工程中常用的一种节点形式,但是我国《钢结构设计规范》中却没有相应的内容与之对应,这给设计工作带来了困难。本文运用ANSYS有限元程序,在考虑材料非线性和几何非线性的基础上,对空间KX型圆管相贯节点的极限承载力进行数值模拟,得到其应力的发展变化过程及节点的变形,并着重分析了截面尺寸(包括支管与主管直径比β、支管径厚比di/ti、主管径厚比d/t等参数)对极限承载力的影响。最后总结出该类节点极限承载力随上述各个参数变化的规律,供工程实践参考。     

Verification Experiment of Threshold Detector 107Ag(n,n′)107mAg on “YAYOI” Standard Neutron Field

The validity of the ¹⁰⁷Ag(n, n′)^107mAg reaction for reactor neutron dosimetry has been examined through an irradiation experiment using the standard neutron field in the “YAYOI”, a fast neutron source reactor. The test foil used was 99.0% ¹⁰⁷Ag enriched silver, which was irradiated along with five reference foils already well evaluated. The reaction rate of 107Ag was determined by K X-ray counting with a high-purity Ge detector. The cross section for the ¹⁰⁷Ag(n, n′) ^107mAg reaction was compiled from the excitation cross section data of ¹⁰⁷Ag published in ENDF/B-IV, in combination with the decay scheme of ^107mAg listed in the “Table of Isotopes“. Using the neutron spectrum which had previously been precisely measured, it was found that the compiled activity of ^107mAg was underestimated by 12.8±5%. This error is attributed to significant underestimation involved in the cross section of the ¹⁰⁷Ag(n, n′)^107mAg reaction.     

基于Globus的网格安全认证模型的研究与实现

在分析了当前广泛采用的身份认证机制的基础上,结合网格发展的需要,研究了不同网格环境下GSI方案和KX.509方案.借鉴KX.509的代理思想,在Globus环境下提出了一种采用Web登陆模块构建的网格身份认证模型,并加以实现,为校园网格用户提供透明的证书生成、使用和管理.用户在注册和认证过程中,Web登陆模块自动为用户产生数字代理证书,使用户不需拥有自己的数字证书.     

基于KX165的VOR导航显示

文章阐述了基于AlliedSignal公司KX165的VOR导航信息的综合显示技术。文章对VOR导航基本原理及概念进行了清晰的描述,并结合项目经验介绍了KX165设备VOR导航相关的信号采集处理、参数计算及在主飞行显示器上的信息显示,项目相关飞行显示器已经通过了试飞验证。     

网格环境下安全认证模型

网络安全认证技术应用最广泛的是Kerberos认证机制和基于X.509证书的认证机制,两种机制都无法直接单一地应用在网格环境下,设计一种层次域的认证模型,将网格环境分为3个层次信任域。主要解决如何将X.509证书转化为Kerberos票据的问题,提出一种协议密钥独立于用户口令的密钥生成方式,最后通过实验和理论分析,来验证改进的方案安全性。     

对二甲苯/间二甲苯在KX和CaX上的吸附平衡和动态吸附性能

通过静态吸附实验,测定了对二甲苯、间二甲苯在分子筛KX和CaX上的吸附速率曲线及吸附等温线;动态吸附穿透实验测定了对二甲苯/间二甲苯混合液在固定床中的连续流出曲线。结果表明,对二甲苯、间二甲苯在CaX上的静态饱和吸附量和动态穿透吸附量均高于KX,但CaX对对二甲苯的吸附选择性不及KX;Langmuir吸附等温线方程可以很好地拟合对二甲苯、间二甲苯在CaX上的等温线;二级吸附速率方程可以较好地描述对二甲苯、间二甲苯的吸附动力学行为。     

Measurement of the Relative Intensity of 103Pd Photon Radiation

The intensity of photon radiation with energies of 20.15, 22.77, 295, and 497 keV in the decay of ¹⁰³Pd has been measured relative to the 357-keV spectral line. The results have confirmed that there is a discrepancy between the evaluated data for ¹⁰³Pd KX and gamma radiation. An interrelated system of absolute intensities for those energies is proposed.