Enhancing the dimethyl ether carbonylation performance over hydrogen-type mordenites modified by pyrazole hydrochloride

Hydrogen-type mordenite (HMOR) modified with pyrazole hydrochloride (Pya·HCl) was prepared by the ion exchange method. The results showed that Pya·HCl introduction significantly improved the activity and stability of HMOR in the carbonylation reaction of dimethyl ether (DME) to methyl acetate (MA). Small pyrazole ions (HPya⁺) entered into the twelve-membered ring (12-MR) pores of HMOR and selectively replaced part of the Brønsted acid (BAS), thus suppressing the formation of carbon deposits. The modified HMOR presented a larger specific surface area and pore volume, which provided larger channels for molecular diffusion. Additionally, non-framework aluminum was removed by the acidic Pya·HCl solution, resulting in the formation of mesopores, which facilitated the migration of carbon-deposited species from the inside of the zeolite to the outside.

Hydrogen-type mordenite (HMOR) modified with pyrazole hydrochloride (Pya·HCl) was prepared by the ion exchange method.     

Serologic markers for staging human immunodeficiency virus infections

In the present study, 80 serum specimens were tested for human immunodeficiency virus (HIV) antibody by enzyme immunoassay (EIA) and indirect fluorescent antibody tests, HIV (p24) antigen, and Western Blot analyses. A total of 40 specimens were HIV antigen-positive, 35 were antigen-negative and five were indeterminant. Among the 40 antigen-positive sera, 38 had positive antibodies by EIA with confirmation by Western Blot. Two cases were antigen-positive and were thought to be early stages where antibodies had not yet developed. Among the 38 sera, 30 (79%) had decreased or had no reactions by indirect fluorescent antibody tests. Among the 35 antigen-negative cases, all 35 had positive antibodies by EIA and all 35 had bands at gp41 by Western Blot. Among 84 HIV-infected patients, 30 had >400 CD4+ cells per cubic millimeter, 21 patients had 200–400 CD4+ cells and 33 had <200 CD4+ cells. A total of 28 (93%) of the HIV antigen-negative cases with full banding patterns by Western Blot had >400 CD4+ cells. In contrast 18 (55%) of the patients with antigen positivity and incomplete banding on Western Blot had <200 CD4+ cells.     

Age-dependent changes in myocardial ultrastructure during anoxia

We have examined left ventricular function and structure of male C57BL/6J mice at 3 and 24 months of age prior to, during and 5 min following a 3-min exposure to anoxia. During anoxia young hearts were characterized structurally by the presence of clear, abnormal non-membrane bound lipid-like vacuoles closely associated to mitochondria. Myelin figures were also present, and mitochondrial ATPase was considerably reduced. By the end of the 3-min period of anoxia hearts in young mice had irreversibly failed, and upon reoxygenation mitochondria underwent further degradation, including loss of internal structure. While continuing to function throughout anoxia, hearts of old mice had normal appearing myofibrillar, mitochondrial and sarcoplasmic structures. During reoxygenation occasional myelin figures were seen in senescent myocardium, although mitochondrial ATPase was not affected. At all times of anoxia and recovery pathological changes were more extensive in young mice than in their aged counterparts.     

量子点电化学发光的研究现状

本文介绍了近年来基于量子点电化学发光的最新研究进展,叙述了以量子点为基础的电化学发光在免疫检测和其它检测方面的应用现状,最后探讨了量子点电化学发光传感器在生化检测中的应用前景和面临的挑战.     

临床大肠埃希菌第Ⅰ类整合子检测及耐药基因盒分析

目的对来自临床腹泻患者大肠埃希菌的第Ⅰ类整合子分布及其耐药基因盒的结构特征进行分析。方法应用聚合酶链反应（PCR）方法检测第Ⅰ类整合酶基因intⅠ阳性菌株，并对其整合的耐药基因进行测序及序列分析。结果在40株大肠埃希菌中有28株（70％）第Ⅰ类整合酶基因阳性。耐药基因盒扩增结果，13株菌得到1664bp的扩增产物，10株得到1586bp的产物，3株得到1009bp的产物，2株得到1009bp和1586bp两种不同产物。序列分析结果表明，1664bp携带aadA5和dfr17，1586bp携带aadA1和dhfrⅠ，均为对氨基糖苷类抗生素壮观霉素、链霉素和磺胺类药物甲氧苄氨嘧啶产生耐药的基因盒；1009bp为aadA23b，为对氨基糖苷类抗生素壮观霉素、链霉素产生耐药的基因盒。结论测出的28株第Ⅰ类整合子阳性菌株携带耐氨基糖苷类抗生素的基因，应从基因水平上对细菌耐药及其传播进行监测。     

胶原/生物活性玻璃/壳聚糖增强型复合支架

背景：生物活性玻璃/胶原复合材料具有优良的成骨活性和的生物学性能,然而其在人体环境中易降解而导致支架溃散、力学性能下降。 目的：构建具有良好力学性能、抗降解性能和骨修复特性的胶原/生物活性玻璃/壳聚糖增强型复合支架。 方法：以壳聚糖作为分散剂,将生物活性玻璃粉体预先在壳聚糖溶液中均匀分散,然后与胶原溶液混合,结合冷冻干燥法制备多孔胶原/生物活性玻璃/壳聚糖增强型复合骨修复支架。采用傅里叶变换红外光谱仪、场发射扫描电子显微镜、X射线衍射仪、动态生物力学试验机等对复合支架的结构和性能进行表征。 结果与结论：由于壳聚糖和生物活性玻璃粉体在微酸性环境下的电荷吸引,使在壳聚糖中预分散的生物活性玻璃颗粒在复合支架中分散更均匀;壳聚糖的引入大量增加了机体中的羟基和氨基,使分子间的相互作用增强,显著提高了材料的抗压模量和强度;壳聚糖和胶原在分子尺度的混合,使胶原分子被壳聚糖包裹,降低了胶原酶对胶原分子的酶切能力,显著提高了复合支架的抗胶原酶解性;壳聚糖分子使生物活性玻璃颗粒更均匀的包裹在大分子基相中,减少了生物活性玻璃颗粒的团聚和暴露,导致复合支架在模拟体液中的矿化活性略微降低。