人工心瓣用热解炭断裂韧性研究及断口形貌分析

人工心瓣中常用材料主要是包覆在石墨基体上的热解炭。为研究人工心瓣用热解炭材料断裂韧性,采用MTS电动力学测试系统,对石墨、纯热解炭及不同厚度热解炭包覆石墨复合材料4种DC(T)圆盘样品进行紧凑拉伸实验,利用实验所得数据绘制载荷-位移(P-V)曲线,根据ASTM标准E399规定的方法确定临界载荷值以及计算断裂韧性值,并对样品断口形貌进行显微观察。结果表明:两种热解炭包覆石墨复合材料断裂韧性值大于纯热解炭以及石墨的相应值,石墨断裂韧性值大于纯热解炭断裂韧性值;在热解炭包覆石墨复合材料中,涂层与基体厚度比值大的对应断裂韧性值反而小;显微观察热解炭断口较为平整,石墨断口较为粗糙,且热解炭及石墨在裂纹扩展区以及过载断裂区的断口形貌基本上是一致的。     

Electroactive High‐Temperature Shape Memory Polymers with High Recovery Stress Induced by Ground Carbon Fibers

Electroactive shape memory polymers (SMPs) are suitable for remote controllable actuators or applications where direct heat is inconvenient, and herein an electroactive shape memory polyimide (EASMPI) is reported for the first time. EASMPI is synthesized by incorporating ground carbon fibers (GCFs) into a polyimide matrix to form a compact conductive network, and percolation threshold of 0.312 S m^?1 meets the demands of both electroactive and shape memory effects. The glass transition temperature of 302 °C for EASMPI is much higher than that of other electroactive SMPs, and its shape recovery is activated effectively by a voltage of 15.87 V. Recovery stress is crucial for shape memory materials to output work, and EASMPI produces high recovery stress of 40.1 MPa. The possible mechanisms are discussed, and GCF mainly accounts for its electroactivity and recovery stress. EASMPI shows vast potential in practical applications with its electroactive shape memory effect and high recovery stress at high temperature.     

Improving the Acid and Base Resistance of Polyurethane Using Carbon Nanotubes

This paper demonstrates that carbon nanotubes (CNTs) can be used as an effective filler for inhibiting the hydrolysis of polyurethane (PU) under acidic and basic conditions. Although it has been reported that CNTs can quench the radicals on its surface, for the first time, it is confirmed that CNTs undergo reactions that have an inhibiting effect on ion‐mediated hydrolysis. Attenuated total reflectance–infrared spectroscopy measurements on PU and PU–CNT samples reveal that CNTs inhibit the hydrolysis of PU in both acid and alkaline environments. Via quantum chemical calculations, it is shown that CNTs can trap H⁺ ions and OH^? ions on their surface. It is also shown that CNTs can trap multiple ions, even though electrical repulsion is to be expected. The results reveal that CNTs can also function as a hydrolysis inhibitor in addition to their known functions as an antioxidant.     

Decoration of Zinc Oxide Nanorods into the Surface of Activated Carbon Obtained from Agricultural Waste for Effective Removal of Methylene Blue Dye

Zinc oxide (ZnO) nanorods incorporated activated carbon (AC) composite photocatalyst was synthesized using a hydrothermal process. The AC was prepared from lapsi (Choerospondias axillaris) seed stone, an agricultural waste product, found in Nepal by the chemical activation method. An aqueous suspension of AC with ZnO precursor was subjected to the hydrothermal treatment at 140 °C for 2 h to decorate ZnO rods into the surface of AC. As-obtained ZnO nanorods decorated activated carbon (ZnO/AC) photocatalyst was characterized by various techniques, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) spectroscopy. Results showed that highly crystalline hexagonal ZnO nanorods were effectively grown on the surface of porous AC. The photocatalytic property of the as-prepared ZnO/AC composite was studied by degrading methylene blue (MB) dye under UV-light irradiation. The ZnO/AC composite showed better photocatalytic property than that of the pristine ZnO nanorods. The enhanced photocatalytic performance in the case of the ZnO/AC composite is attributed to the combined effects of ZnO nanorods and AC.     

水中邻苯二甲酸酯吸附材料的研究进展

邻苯二甲酸酯(PAEs)被广泛应用于食品包装、玩具和医疗产品,以改善其塑性和弹性。PAEs易于向水体中迁移,并因其具有内分泌干扰特性而成为目前最受公众关注的污染物之一。笔者总结了目前吸附法处理PAEs的最新研究和发展趋势,重点综述了各类吸附材料如活性炭、壳聚糖、人工合成树脂、粘土矿物材料对PAEs的吸附效能和机制,并在此基础上对吸附法处理PAEs的发展方向进行展望。     

Erbium-Doped Amorphous Carbon-Based Thin Films: A Photonic Material Prepared by Low-Temperature RF-PEMOCVD

The integration of photonic materials into CMOS processing involves the use of new materials. A simple one-step metal-organic radio frequency plasma enhanced chemical vapor deposition system (RF-PEMOCVD) was deployed to grow erbium-doped amorphous carbon thin films (a-C:(Er)) on Si substrates at low temperatures (<200 °C). A partially fluorinated metal-organic compound, tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate) Erbium(+III) or abbreviated Er(fod)₃, was incorporated in situ into a-C based host. Six-fold enhancement of Er room-temperature photoluminescence at 1.54 μm was demonstrated by deuteration of the a-C host. Furthermore, the effect of RF power and substrate temperature on the photoluminescence of a-C:D(Er) films was investigated and analyzed in terms of the film structure. Photoluminescence signal increases with increasing RF power, which is the result of an increase in [O]/[Er] ratio and the respective erbium-oxygen coordination number. Moreover, photoluminescence intensity decreases with increasing substrate temperature, which is attributed to an increased desorption rate or a lower sticking coefficient of the fluorinated fragments during film growth and hence [Er] decreases. In addition, it is observed that Er concentration quenching begins at ~2.2 at% and continues to increase until 5.5 at% in the studied a-C:D(Er) matrix. This technique provides the capability of doping Er in a vertically uniform profile.     

养心定悸胶囊调控NOS途径改善心肌缺血再灌注损伤及其引起的心律失常

目的：明确养心定悸胶囊对心肌缺血再灌注损伤及其诱导的心律失常的保护作用及分子机制。方法：采用Langendorff离体心脏灌流系统及缺氧/复氧H9c2心肌细胞模型，考察养心定悸胶囊灌注给药对大鼠心脏左室发展压（LVDP）、左心室舒张末压（LVEDP）、左室内压上升/下降速率（±dp/dt）、心率失常相关指标，以及大鼠心肌氧化应激相关指标的影响，同时考察养心定悸胶囊含药血清对心肌细胞模型细胞活力，乳酸脱氢酶（LDH）、一氧化氮（NO）、一氧化氮合酶（eNOS，iNOS）活性及蛋白表达的影响。结果：养心定悸胶囊灌注前后均可以有效改善大鼠血流动力学，其中灌注前给药组对大鼠心脏停跳时间，心脏恢复正常律动时间及心率失常持续时间的改善作用均优于灌注后给药；养心定悸胶囊含药血清可以有效提高细胞活力，降低细胞LDH水平，升高细胞eNOS活性，降低细胞iNOS活性及NO含量，并升高磷酸化eNOS蛋白表达，抑制iNOS蛋白表达。结论：养心定悸胶囊可以有效改善心肌缺血再灌注损伤及其引起的心律失常，其作用机制与调控心肌一氧化氮合酶及NO水平相关。     

Chemical composition,antioxidant activity and hepatoprotective potential of Rourea induta Planch. (Connaraceae) against CCl4-induced liver injury in female rats

ObjectivesThe aim of this study was to evaluate the flavonoid content of an ethanolic leaf extract from the medicinal plant Rourea induta Planch. (RIEE) and to investigate its hepatoprotective potential and in vivo antioxidant effects.MethodsUsing samples from carbon tetrachloride-treated Wistar female rats treated orally with or without RIEE, we evaluated the aspartate aminotransferase, alanine aminotransferase, and total bilirubin levels in plasma; the levels of the hepatic oxidative stress markers catalase, superoxide dismutase, glutathione peroxidase, and reduced glutathione in liver homogenates; and the thiobarbituric acid reactive substance levels. A histopathology study was performed. A quantitative analysis of the RIEE extract was performed using high-performance liquid chromatography to evaluate its flavonoid content.ResultsOral administration of RIEE significantly reduced carbon tetrachloride-induced elevations in the levels of plasma markers of hepatic damage and lipid peroxidation. It also rescued histopathologic alterations observed in the liver and levels of oxidative stress markers.ConclusionsRIEE exhibits antioxidant and hepatoprotective activities in vivo, which may be attributable to its flavonoids composition [hyperin (2), quercetin-3-O-β-xyloside (4), quercetin-3-O-α-arabinofuranoside (5), and quercetin (6)].