聚α-烯烃减阻剂本体聚合法连续生产的研究

在1L的搅拌釜式反应器中,以α-十二烯为原料,主催化剂为负载型TiCl4/MgCl2,助催化剂为三异丁基铝（齐格勒-纳塔催化剂）,外给电子体为DDS（二苯基二甲氧基硅烷）,采用本体聚合法,探索了一种连续生产油溶性减阻剂的方法。考察了在该工艺条件下,催化剂的用量及其配比、反应温度和反应时间对聚合物性能的影响,利用室内环道评价装置测定了聚合物的减阻率。研究结果表明,该方法能连续稳定的生产减阻率达到40%左右的减阻剂产品,满足工业生产的要求。     

干扰素α2b基因真核表达质粒的构建及表达

目的构建干扰素α2b(IFNα2b)基因真核表达质粒,并在CHO-dhfr-细胞中表达。方法从DH5α-pbv220-IFNα2b工程菌中扩增IFNα2b基因片段,克隆入psv-dhfr质粒中,构建重组真核表达质粒psv2-dhfr-IFNα2b,转染至CHO-dhfr-细胞中,经MTX加压筛选,获得稳定生长的单克隆细胞株。采用Wish细胞病变抑制法检测转染细胞中IFNα2b的抗病毒活性;提取细胞基因组DNA,进行PCR鉴定。结果重组真核表达质粒psv2-dhfr--IFNα2b经PCR及双酶切鉴定证明构建正确;转染后的重组细胞表达的IFNα2b具有抗病毒活性,且活性较强;以转染细胞基因组DNA为模板,可扩增出IFNα2b基因条带。结论已成功构建IFNα2b基因真核表达质粒,并在CHO-dhfr-细胞中表达了具有生物学活性的IFNα2b蛋白,为进一步对IFNα2b进行真核表达的研究奠定了基础。     

Preparation of micrometer-sized α-Al2O3 platelets by thermal decomposition of AACH

Micrometer-sized α-Al₂O₃ platelets with hexagonal shape were prepared by thermal decomposition of ammonium aluminum carbonate hydroxide (AACH) using AlF₃ as an additive. The precursor and the calcined product were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and differential scanning calorimetry. The α-Al₂O₃ platelets with the size of 2-3 μm were obtained by calcining AACH at 1200 °C with 5 wt.% AlF₃. The morphology modification is attributed to the various growth rates along different crystal orientations due to the adsorption and uneven distribution of AlF₃. A step growth mode is responsible for the formation of the platelets.     

4-氟-α-(2-甲基-1-氧丙基)-γ-氧-N,β-二苯基-苯丁酰胺的合成

以苯乙酸为原料,4-氟苯基苯乙酮在HBr/H2O2作用下发生α-溴代,合成2-溴-1-(4-氟苯基)-苯乙酮,再与异丁酰乙酰苯胺在碱性条件下发生α-碳上的取代反应,得到阿托伐他汀钙的关键中间体4-氟-α-(2-甲基-1-氧丙基)-γ-氧-N,β-二苯基-苯丁酰胺,总收率57.3%。化合物结构经核磁、质谱得到确认。     

A Versatile Endoribonuclease Mimic Made of DNA: Characteristics and Applications of the 8–17 RNA‐Cleaving DNAzyme

Enzymes play a crucial role in all living organisms by accelerating the rates of a myriad of biochemical reactions that are necessary to sustain life. Although the vast majority of known enzymes are made of protein, in recent years it has become increasingly apparent that other molecular formats, like nucleic acids, can also serve in this capacity. DNAzymes (also known as deoxyribozymes) are synthetic enzymes made of short, single strands of deoxyribonucleic acid. These DNA‐based enzymes offer the prospect of significant commercial utility, because they are exceptionally stable and can be produced very easily and inexpensively. The study of one particular DNAzyme, known as “8–17”, has enhanced our understanding of DNAzyme‐mediated catalysis. Moreover, the function of 8–17 has been regarded with special importance because it can catalyze sequence‐specific cleavage of RNA, a reaction that has broad implications in biotechnology and biomedical fields. In this review, we explore the creation, characterization, and application of the 8–17 RNA‐cleaving DNAzyme.     

三氢化铝制备工艺及稳定性研究进展

综述了三氢化铝(AlH3)的晶体形态特征,以及α-AlH3的性质、合成方法、表征和稳定化方法,着重讨论了获得高质量α-AlH3结晶的条件和操作方式。     

涂层结构和表面的优化设计对硬质合金涂层刀具寿命影响的研究

采用中、高温连续复合化学气相沉积技术(MHT-CVD)在硬质合金刀具上沉积了经过结构优化的厚膜α-Al2O3涂层,并对涂层表面进行了抛光处理,通过扫描电镜和表面粗糙度测量表征了涂层的微观结构和表面质量,并对经过优化的涂层硬质合金刀具进行了切削测试。研究表明,经过优化的涂层刀具在表面质量和使用寿命上有了较大幅度的提升。     

CuO-ZnO-MnO_x/Al_2O_3催化剂上α,α-二甲基苄醇氢解制备异丙苯

采用沉积沉淀法制备了CuO-ZnO/Al2O3和CuO-ZnO-MnOx/Al2O3催化剂。利用XRD、低温N2吸附、H2-TPR等手段对两种催化剂进行了表征。表征结果显示,Mn物种的引入不仅有效促进了Cu组分的分散,且能增强Cu的抗烧结能力,提高了活性组分的稳定性。利用常压高空速的催速失活实验对两种催化剂催化α,α-二甲基苄醇(DMBA)氢解的性能进行了比较,实验结果表明两种催化剂的初始活性相当,但CuO-ZnO-MnOx/Al2O3催化剂的稳定性更高。在入口温度170℃、出口温度220℃、H2压力2.0MPa、氢油体积比400、LHSV1.0h-1的条件下,用Mn与Cu摩尔比为0.2的CuO-ZnO-MnOx/Al2O3催化剂催化反应1000h,DMBA完全转化,异丙苯选择性大于96%。     

High surface area α-alumina preparation by using urban waste

A new method for preparing high surface area α-alumina from urban waste is proposed. The method consists of the precipitation of a precursor that contains bohemite mixed with a linear polymer and subsequently the thermal decomposition of the precursor by heating in nitrogen and air to 1200 °C. The resulting α-alumina consists of nanocrystals of about 100 nm aggregated into larger particles with relatively high surface area (12 m² g⁻¹) and a significant macropore volume of 0.545 cm³ g. Methods of X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) were used to characterize microstructure of prepared materials. Results of differential thermal analysis, thermogravimetry and emanation thermal analysis characterized the thermal behaviour of α-alumina precursors.     

不同粒径的α-Fe_2O_3对KClO_3热分解催化性能的研究

通过热重分析法研究了微米Fe2O3和纳米Fe2O3对KClO3热分解的催化性能,用非等温热分析方法研究了纯KClO3、微米Fe2O3催化的和纳米Fe2O3催化的KClO3热分解机理。结果表明,微米Fe2O3和纳米Fe2O3对KClO3热分解均有催化作用,纳米Fe2O3的催化性能比微米Fe2O3的催化性能好,纯KClO3热分解由一维扩散动力学机理控制,活化能E=177.9 kJ/mol,指前因子A=6.3×107;微米Fe2O3催化的KClO3热分解,由三维扩散动力学机理控制,活化能E=118.0 kJ/mol,指前因子A=9.7×105;纳米Fe2O3催化的KClO3热分解,由二级化学反应动力学机理控制,活化能E=68.7 kJ/mol,指前因子A=6.2×104。