负载型Cu-Pd系催化剂的化学吸附性质及催化加氢活性

本文研究了负载型铜催化剂中加入少量Pd后对其化学吸附性质和对顺丁烯二酸酐加氢活性的影响。实验结果表明Pd的引入使催化剂对一氧化碳的化学吸附量显著增加,催化剂的加氢活性和相对稳定性也显著提高,并使催化剂的还原温度范围降低。催化剂的组成、制备方法不同,其化学吸附性质和加氢活性也有较大的差异。催化剂的还原温度、对一氧化碳的化学吸附容量和其催化加氢活性之间显示出良好的顺变关系,催化剂在230—290℃温度范围内还原,对一氧化碳的化学吸附量最大,加氢活性也最高。     

Specific localization of the catalytic subunits of protein kinase CK2 at the centrosomes

The protein kinase CK2 holoenzyme is composed of two regulatory β subunits and two catalytic α or α' subunits. Although experimental evidence for involvement of the enzyme in the regulation of cell proliferation is accumulating, the exact mechanism of its action is still unclear. The subcellular localization of the enzyme may be a key to its function. We have recently shown that the CK2 holoenzyme is tightly associated with the Golgi complex and the endoplasmic reticulum. Centrosomes, which organize spindle formation during the cell cycle and microtubule cytoskeleton formation and, thereby, the location and orientation of different organelles in the cell, are in close vicinity to the Golgi complex. Because several kinases and phosphatases have been described to regulate the functions of the centrosome, we analysed the association of CK2 with these organelles. Using biochemical cell fractionation and coimmunoprecipitation, we never found the holoenzyme but only the catalytic asubunits associated with the centrosome. These data were confirmed by immunoelectron microscopy. Thus, the present data point to a particular role of the catalytic α and α' subunit of protein kinase CK2, which may be different from their roles in the holoenzyme. Received 2 August 2002; received after revision 2 October 2002; accepted 22 October 2002 RID="*" ID="*"Corresponding author.     

Deoxyribozymes: new activities and new applications

DNA in its single-stranded form has the ability to fold into complex three-dimensional structures that serve as highly specific receptors or catalysts. Only protein enzymes and ribozymes are known to be responsible for biological catalysis, but deoxyribozymes with kinetic parameters that rival ribozymes can be created in the laboratory. Some of these engineered DNA catalysts are showing surprising potential as therapeutic agents, which makes them biologically relevant if not biologically derived. If DNA's natural role is strictly genomic, how significant is its innate catalytic prowess? New examples of engineered deoxyribozymes serve as empirical examples of the potential for catalysis by DNA. These results indicate that the true catalytic power of DNA is limited by discovery and not by chemistry.     

天然气汽车均流三元催化器内流动阻力特性

对添加了均流装置的天然气汽车尾气催化转化器内的流场阻力特性进行了数值研究.结果表明:改变载体安装位置对催化器内的压力损失影响很明显.催化器内添加均流装置会增大催化器段的压力损失,但采用合理的均流装置会使催化器内压力损失增加得较小.组合式导流板造成的压力损失对发动机影响很小,均流装置可以显著改善催化器内的流场均匀性.采用合理的导流结构和安装位置可以使压力损失较小.     

纳米CuO/CeO2制备、表征及对甲烷燃烧催化活性

文中用柠檬酸络合法制备了纳米稀土复合氧化物Cu_xCeO_δ，以透视电子显微镜（TEM）、热重-差热分析（TG-DTA）、Brunauer Emmett Teller（BET）比表面和X射线衍射分析（XRD）、粒度二次分布仪等方法表征了复合物粉末的粒径、热稳定性、比表面、晶相和二次粒度分布，以常压微型固定床反应器考察了该复合物催化剂对甲烷燃烧的催化活性。研究了复合物中CuO含量和焙烧温度对催化活性的影响，并初步探讨燃烧反应的机理。     

催化动力学光度法测定痕量亚硝酸根

研究在稀盐酸介质中,亚硝酸根对溴酸钾氧化罗丹明B褪色的催化反应,建立测定痕量亚硝酸根的催化反应光度法.该方法测定亚硝酸根的最大吸收波长540nm,表观摩尔吸光系数为2.9×105L·mol-1·cm-1.方法检出限为8.27×10-10g·mL-1在0～6.5μg/25mL范围内符合比耳定律,用于水果、蔬菜、肉制品、罐头样品中痕量亚硝酸根的测定,结果满意.     

金属有机催化反应在超临界CO2流体中的研究进展

超临界CO2流体作为绿色替代溶剂进行金属有机化学催化反应是目前研究的热点之一．介绍了超临界CO2流体的性质以及Rh、Ru、Fe、Ir、Mg等金属有机催化反应，综述了近十年来国内外在这方面的研究进展．     

氧化钙条件下焦油主要组分的催化裂解

为降低煤气化时焦油产率、提高煤气产率，利用固定床反应器研究了焦油的两种主要组分苯和甲苯在氧化钙条件下的裂解反应特性，探讨了氧化钙的催化机理。实验结果表明，与石英砂条件下相比，氧化钙在苯和甲苯裂解反应中具有催化作用，改变了反应路径，使苯和甲苯裂解活化能分别下降２８．６６％，４７．８７％，频率因子分别下降３，６个数量级；相同转化率所需温度分别下降约１５０℃，１００℃；碳析出量降低，气态裂解产物总产率提高。     

热处理工艺CAD软件系统开发研究

在IBM-486微机上,利用QBASIC语言及FoxBASE关系数据库系统联合编程,建立了热处理工艺及材料库和文献库两个数据库,开发了一套热处理工艺CAD软件系统.系统采用模块结构,包含热处理工艺及材料数据库管理子系统.热处理工艺卡片输入与管理系统.热处理工艺设计子系统、渗碳工艺CAD软件子系统和材料文献检索子系统五个子模块.该软件系统功能较全.结构合理,具有较强的实用性和可推广性.