火焰原子吸收光谱法测定高纯石英粉中痕量钙

系统地研究了用空气——乙炔火焰原子吸收光谱分析法测定高纯石英粉中钙的最佳条件，建立了14％的乙醇作为增感剂，在2％盐酸介质中，0．4％ LaCl3溶液作为释放剂，用塞曼火焰原子吸收法测定的可行性方案，探讨了共存元素对钙的干扰及其消除。方法操作简便快速，干扰少，方法相对标准偏差小于3％，适用于日常分析石英粉中的杂质。     

Selective oxidation of styrenes under oxygen catalyzed by cobalt chloride

The cobalt(II) chloride-catalyzed oxidative cleavage of -methylstyrene with oxygen in t-BuOH gives acetophenone and formaldehyde in good yield. The competing reactions between C=C cleavage and formation of polymeric products are strongly affected by the solvent, cobalt catalyst and concentration used, as well as the reaction temperature. A free radical mechanism involving a cyclic peroxide intermediate is proposed to give the cleavage products. Oxidation of various alkenes using CoCl₂/t-BuOH/O₂ system shows that only activated styrenes can be oxidized effectively. The reactivity of various styrenes and their selectivity towards giving cleavage products or polymers are strongly influenced by the electronic and steric properties of the substrate.     

20＂通径中压球阀的设计和三维数值模拟

介绍了通径为20＂（1＂=25．4mm）的大口径中压球阀阀体、新型C形金属密封环组件等的结构设计；在阀座与球体之间采用整体碟形弹簧和新型阀座密封填料，以保证高压密封，提高使用寿命；阀芯采用空心球体结构和分段冲压成形加工工艺，有效地保证了球体的加工精度和质量，降低了生产成本；在结构设计中，充分考虑了球阀的密封、防火、启闭传动及制造工艺的要求；对其中结构复杂的球阀阀体和空心球形阀芯进行了强度计算和ANSYS应力、应变模拟分析计算，二者计算结果一致，并认为阀体的厚度由其大开孔处局部应力的整体补强确定。     

大型机械轴承相对标高测试系统

介绍了一种使用连通管、电涡流传感器测量轴承相对标高的测试系统,它能准确测量大型机械相邻轴承的相对标高变化.文中叙述了其测量原理、特点以及系统的硬件电路和软件设计,最后给出一个测试实例,并对测量结果进行了简要分析.     

Synthesis and characterization of novel polyesterimides

A series of soluble novel polyesterimides was synthesized from diamines [a mixture of 2,2‐bis(4‐(4‐aminophenoxy)phenyl)propane (BAPP) with amine‐terminated polysiloxane (ATPS) in various mole ratios] and the ester‐group‐containing dianhydrides. The ester group containing dianhydrides in turn was synthesized by the transesterification reaction of trimellitic anhydride (TMA) with diacetate ester of hydroquinone (HQ), 4,4′‐dihydrophenyl (BP), 1,6‐hexanediol, or ethylene glycol. The resulted polyesterimides were characterized by using Fourier‐transform infrared spectroscopy, inherent viscosity, solubility, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The polyesterimides of BP and HQ had relatively high glass transition temperatures in the range of 214.7–227.2 and 195.7–210.5°C, respectively. The glass transitions decreased rather slowly with the increase in polysiloxane content. Thermal stability and the weight‐loss behavior of polyesterimides were studied by TGA. All polyesterimides of BP and HQ (BPI and HQI) showed no significant weight loss below 500°C in a N₂ environment, and the decomposition temperatures (T_d5%) of BPI and HQI were >520°C. Most polyesterimides were soluble in polar aprotic solvents and m‐cresol. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 730–738, 2004     

熔块中的气泡缺陷及其解决办法

分析了熔块生产中气泡缺陷产生的各种原因．提出了实际生产中的注意事项和具体的解决办法。     

新型甲醇汽油的制备及性能测试

本文研究了甲醇汽油体系相稳定剂,并利用90~#基础汽油和工业精甲醇为主要原料,添加相稳定剂、防腐剂、消烟剂、蒸汽压调节剂和燃烧催化剂等,经科学配方和工艺,成功制备出高性能符合97~#无铅车用汽油国标的甲醇汽油产品。     

新型碳质催化剂用于NH3选择性催化还原NOx的研究

以城市污水处理厂剩余污泥为原料制备了一种新型碳质催化剂。通过试验考察了催化剂在NH₃选择催化还原NO中的应用效果。结果表明,催化性能较好，最佳的制备和催化反应条件为：锌铁物质的量比1∶0.5，热解温度750 ℃，反应温度400 ℃，O₂浓度15%。在此条件下，NOx的最大转化率达98.3%。通过考察证明催化剂自身具有一定的还原性能。对催化剂进行了FTIR、TG、SEM和BET分析，结果表明，催化剂具有很丰富的孔结构、活性粒子和表面官能团，比表面积较大，最大可达307 m²·g^-1，分析结果显示具有良好的催化条件。     

联苯型双醚二酐的合成及其表征

以4,4′二羟基联苯(联苯二酚)和N甲基4硝基邻苯二甲酰亚胺为主要原料,在非质子性溶剂中,经缩合得到联苯双醚二酞酰亚胺,再经水解、酸化、脱水等工艺制得联苯型双醚二酐(BPEDA)。通过红外光谱对产品进行了表征,结果符合要求。该单体与4,4′二氨基二苯醚(ODA)在N,N二甲基乙酰胺(DMAc)中缩聚所得聚酰胺酸特性粘度为0.72dL/g。将PI制成薄膜,室温下拉伸强度为98.5MPa,成膜性能良好。     

Effect of Pretreatment Atmosphere on CuO/TiO2 Activities in NO + CO Reaction

Using TiO₂ as carrier, CuO/TiO₂ catalysts with different CuO loading were prepared by the impregnation method. The catalytic activities in NO+CO reaction were examined with a micro-reactor gas chromatography reaction system and the methods of TPR, XPS and NO-TPD. It was found that the catalytic activities were affected by pretreatment atmosphere, i.e. H₂ atmosphere > reduction–reoxidation > 10%CO/He > reaction gas (fresh sample). NO decomposition was better by low-valence Cu species than by high-valence Cu species, i.e. Cu⁰>Cu⁺>Cu²⁺. The XPS results indicated that Cu species on CuO/TiO₂ were Cu⁰, Cu⁺, normal Cu²⁺(Cu²⁺(I)) and chain-structured Cu²⁺(Cu²⁺(II)) as –Cu–O–Ti–O–. The activities of Cu²⁺(II) were much higher than that of Cu²⁺(I), but both species were very unstable in the reaction atmosphere and easily reduced by CO, which accounted for the variable activities of fresh catalysts with increasing reaction temperature. In NO+CO reaction, the redox process was a cycle of Cu⁺–Cu²⁺(I) at low reaction temperature but was a cycle of Cu⁰–Cu⁺ at high reaction temperature. As shown by NO-TPD, high catalytic activities could be attributed to the following factors, e.g. oxygen caves on the catalyst’s surface after pretreatment with H₂ and reduction–reoxidation, formation of Cu⁰ after pretreatment with H₂, and increment of Cu species dispersion and formation of Cu²⁺(II) after pretreatment with reduction–reoxidation.