Electrochemical micromachining of nitinol by confined-etchant-layer technique

The confined etchant layer technique has been applied to fabricate complex three-dimensional microstructures on nitinol for the first time. HF and HNO₃ were locally and simultaneously electrogenerated at the mold surface to etch a nitinol workpiece. NaOH was used as an efficient scavenger to confine the etchant close to the mold. Cyclic voltammetry was employed to study the electrochemical behavior of a Pt electrode in the etching solution in order to choose an appropriate potential for etchant generation on the mold. The thickness of the confined etchant layer was estimated to be several micrometers by inspecting the deviation of the sizes of the etched spots from the sizes of those on the microelectrode. Thus, the composition of the electrolyte could be optimized for better etching precision. By optimizing the composition of the electrolyte, complex microstructures on a Pt-Ir mold bearing the logo “XMU” of Xiamen University were successfully fabricated on nitinol. The etched patterns were approximately negative copies of the mold, and the precision of duplication could easily reach the micrometer scale.     

Mass-rearing of the redlegged ham beetle, Necrobia rufipes De Geer (Coleoptera: Cleridae) for laboratory research

A new protocol for mass-rearing the redlegged ham beetle, Necrobia rufipes De Geer, in the laboratory is described, that facilitates the production of large numbers of insects with minimal handling. A culture medium comprised of finely ground (150 μm) dried fish, dry dog food and pieces of dried cured ham was tested on N. rufipes. This rearing medium produced significantly larger population numbers when compared with a range of published and unpublished methods. When reared on this medium with initial colonies of 200 mixed sex adult beetles, there was more than a three-fold increase in N. rufipes adult populations from the original numbers over a 7-8 week period. This simple procedure minimizes cannibalism as the larvae were shifted into glass vials for pupal cell formation.     

Lutein Prevents High Fat Diet‐Induced Atherosclerosis in ApoE‐Deficient Mice by Inhibiting NADPH Oxidase and Increasing PPAR Expression

Epidemiological and experimental studies provide supportive evidence that lutein, a major carotenoid, may act as a chemopreventive agent against atherosclerosis, although the underlying molecular mechanisms are not well understood. The main aim of this study was to investigate the effects of lutein on the alleviation of atherosclerosis and its molecular mechanisms involved in oxidative stress and lipid metabolism. Male apolipoprotein E knockout mice (n = 55) were fed either a normal chow diet or a high fat diet (HFD) supplemented with or without lutein for 24 weeks. The results showed that a HFD induced atherosclerosis formation, lipid metabolism disorders and oxidative stress, but noticeable improvements were observed in the lutein treated group. Additionally, lutein supplementation reversed the decreased protein expression of aortic heme oxygenase‐1 and increased the mRNA and protein expressions of aortic nicotinamide‐adenine dinucleotide phosphate oxidase stimulated by a HFD. Furthermore, the decreased mRNA and protein expression levels of hepatic peroxisome proliferator‐activated receptor‐α, carnitine palmitoyltransferase 1A, acyl CoA oxidase 1, low density lipoprotein receptors and scavenger receptor class B type I observed in mice with atherosclerosis were markedly enhanced after treatment with lutein. Taken together, these data add new evidence supporting the anti‐atherogenic properties of lutein and describing its mechanisms of action in atherosclerosis prevention, including oxidative stress and lipid metabolism improvements.     

小檗碱对高脂血症兔脂代谢及肝脏LDLR和SR-B1基因表达的影响

目的研究小檗碱(Berberine,Ber)对高脂血症兔脂代谢及肝脏低密度脂蛋白受体(Low density lipoprotein re-ceptor,LDLR)和B类1型清道夫受体(Scavenger receptor B1,SR-B1)基因表达的影响。方法取新西兰大耳白兔40只,以基础饲料喂养1周后,随机选取8只为普通饲料组(ND),继续以基础饲料喂养;其余32只以高脂饲料喂养;复制高脂血症兔模型。建模8周后,将模型动物随机分为4组:高脂饲料组(HFD)、高脂饲料+非诺贝特组(FD)、高脂饲料+低剂量Ber干预组(BLD)组和高脂饲料+高剂量Ber干预组(BHD),继续喂养8周,采用全自动生化分析仪测定兔血清总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)和高密度脂蛋白胆固醇(HDL-C)的含量;观察肝脏组织病理学变化;实时荧光定量PCR法检测肝脏组织LDLR和SR-B1基因表达的变化。结果 HFD组TC、TG和LDL-C的表达水平较ND组明显升高(P<0.01),肝脏发生中度脂肪变性和水样变性的病理学改变,而经Ber干预后,血清中TC、TG和LDL-C的表达的水平较HFD组显著降低(P<0.01),且肝细胞脂肪变性和水样变性程度较HFD组有所减轻;HFD组LDLR和SR-B1基因mRNA的表达水平明显低于ND组(P<0.01),经Ber干预后,LDLR和SR-B1基因mRNA的表达水平则较HFD组明显上调(P<0.01)。结论 Ber具有明显的调血脂作用,其作用机制可能是通过上调肝脏LDLR和SR-B1基因的表达,进而抑制肝脏中胆固醇的合成。     

青蒿琥酯增加小鼠腹腔巨噬细胞内化内毒素、大肠埃希菌的作用及可能机制

目的: 观察青蒿琥酯(artesunate, AS)对小鼠腹腔巨噬细胞内化清除脂多糖/内毒素(lipopolysaccharide/endotoxin, LPS)和吞噬大肠埃希菌的影响,并初步探讨其可能的作用机制。方法: MTT法检测不同浓度网格蛋白抑制剂(monodansylcadaverine, MDC)、内体酸化抑制剂氯喹(chloroquine, CQ)对小鼠腹腔巨噬细胞活力的影响,以选择恰当的药物工作浓度;激光共聚焦法检测青蒿琥酯及MDC、CQ对小鼠腹腔巨噬细胞内化FITC-LPS的影响;分别采用激光共聚焦和菌落集落形成计数实验观察青蒿琥酯对小鼠腹腔巨噬细胞内化大肠埃希菌的影响;逆转录PCR检测青蒿琥酯对小鼠腹腔巨噬细胞清道夫受体A(class A scavenger receptor,SR-A) mRNA表达的影响。结果: MDC和CQ浓度分别小于 25 μg/mL 和 20 μg/mL 时对小鼠腹腔巨噬细胞活力无影响;MDC、CQ可抑制小鼠腹腔巨噬细胞内化LPS,青蒿琥酯可增加小鼠腹腔巨噬细胞对LPS的内化,而且青蒿琥酯可增加MDC和CQ处理的巨噬细胞内化LPS的功能。激光共聚焦和菌落集落形成计数实验均显示青蒿琥酯可增加小鼠腹腔巨噬细胞对大肠埃希菌的内化能力。逆转录PCR结果显示青蒿琥酯可增强LPS处理或未处理的小鼠腹腔巨噬细胞SR-A mRNA的表达。结论: 青蒿琥酯可增强小鼠腹腔巨噬细胞内化LPS、大肠埃希菌的能力,该作用可能与SR-A mRNA表达升高有关。     

高交联度易加工硅烷交联管材专用料的研制

介绍了采用二步硅烷交联工艺制备高交联度易加工硅烷交联管材专用料的方法,讨论了基础树脂、助剂对专用料交联度和加工性能的影响;通过加入自由基捕捉剂的方法,抑制接枝反应过程中的碳-碳大分子交联,解决了二步法硅烷交联领域的技术瓶颈问题,使硅烷交联管材专用料既具有高的交联度又具有良好的加工性能.     

Bicarbonate Effect in the Ozone-UV Process in the Presence of Nitrate

Ozonation and advanced oxidation processes (AOP) are very efficient methods for the destruction of refractory organic matters. These virtues have always been related to the production of hydroxyl radicals HO^?, which are extremely powerful and non-selective oxidants. In this study, the O₃-UV process is used as an AOP, where hydroxyl radicals are generated from the photodecomposition of ozone by short wavelength ultraviolet radiation. The obtained results indicated a weak scavenging effect of tert-butanol proving that hydroxyl radicals and ozone are not the only oxidants existing in the medium. Moreover, bicarbonate, known for a long time as effective HO^? radical scavengers, does not slow down the oxidation of benzoic acid, but surprisingly increases it. Chlorides significantly decrease the degradation of organic compounds through their reaction with HO^? radicals to produce chlorine. Carbonate radicals, nitrate and nitrogenated species as peroxynitrite/?peroxynitrous acid are involved in the oxidative mechanisms.     

Research Note Interferences due to Ozone-Scavenging Reagents in the GC-ECD Determination of Aldehydes and Ketones as the (2, 3, 4, 5, 6, -Pentafluorobenzyl) oximes

In order to study ozonation byproduct (OBP) formation as a function of time, it is necessary to quench ozone and thereby fix the concentrations of the byproducts. Reagents chosen for this purpose must not react with the OBPs or otherwise adversely impact the analysis. Six potential ozone-scavenging reagents were tested for possible interference in the GC-ECD determination of aldehydes and ketones after derivatization with O-(2,3,4,5,6-pentafluorobenzyl)oxylamine (PFBOA). All six—sodium nitrite, sodium cyanide, sodium methanoate (formate), indigo-5,5′-disulfonate disodium (Indigo Carmine), indigo-5,5′,7-trisulfonate tripotassium, and tin(II) chloride—were found to interfere in the analysis.     

5’-鸟苷酸(5’-GMP)γ辐解机理研究

本文研究了γ引发5'-鸟苷酸释放无机磷的反应机理,证明在中性水溶液中水辐解产生的OH自由基是引起5’-鸟苷酸释放无机磷的主要活性粒种,H原子对5’-鸟苷酸释放无机磷也有一定的贡献。 用竞争动力学方法测出了OH自由基与5'-鸟苷酸C_4’的反应速率常数为(1.2±0.1)×10~8(mol/L)~(-1)S~(-1)以及与5'-鸟苷酸的反应速率常数为(5.1±0.4)×10~9(mol/L)~(-1)S~(-1)。     

Modification of the Standard Neutral Ozone Decomposition Model

The modified Staehelin, Buhler, and Hoigné model for aqueous ozone decomposition was tested over a wide range of hydroxyl radical scavenger concentrations at a pH of 7.1–7.2. Results from these experiments showed that the modified model appeared to underpredict the residual ozone concentration and overpredict the residual hydroxyl radical probe compound, tetrachloroethylene, concentration. The modified Staehelin, Buhler, and Hoigné model was recalibrated and two rate constants, the rate constant of the initiation reaction of ozone decomposition of hydroxide ion and the rate constant of the promotion reaction of ozone decomposition by hydroxyl radical, were reestimated. The new estimates of these rate constants are 1.8 × 10² M^?1s^?1 (initiation reaction) and 2 × 10⁸ M^?1s^?1 (promotion reaction), while the values estimated by Staehelin, Buhler, and Hoigné for these rate constants are 70 M^?1s^?1 (initiation reaction) and 2 × 10⁹ M^?1s^?1 (promotion reaction). The recalibrated-modified model was tested and validated by conducting experiments at different pH values and hydroxyl radical scavenger concentrations. Also, the effect of phosphate buffer as a hydroxyl radical scavenger was investigated at phosphate buffer concentrations of 10 mM and 1 mM.