Ba0.6Sr0.4TiO3/聚偏氟乙烯-聚甲基丙烯酸甲酯复合材料的制备及其介电性能

采用流延热压工艺制备Ba_0.6Sr_0.4TiO₃(BST)/聚偏氟乙烯(PVDF)?聚甲基丙烯酸甲酯(PMMA)复合薄膜,研究了PMMA含量对复合材料微观组织结构和介电性能的影响规律。结果表明,BST相能够均匀分散在聚合物基体中,归因于PMMA与PVDF良好的相容性,2种聚合物之间的界面不分明;随着PMMA含量的增加,复合材料的介电常数先降低后升高,耐击穿强度和介电可调性先增加后减少。PMMA含量(体积分数)为15%的BST/PVDF?PMMA₁₅复合材料的综合性能最佳:介电常数为23.2,介电损耗为0.07,耐击穿强度为1412 kV·cm^-1,在550 kV·cm^-1偏压场下,介电可调性为26.2%。     

Testing the ONIOM G2R3 model against donor-acceptor dissociation energies of group 13-15 complexes: accuracy comparable to CCSD(T)/aug-CC-pVTZ at a fraction of the resource cost

The ability of the composite three-layer ONIOM G2R3 (OG2R3) method to match experimental dissociation energies for group 13-15 donor-acceptor complexes was examined for a database of 34 complexes. The composite approach provides energies that agree reasonably with experiment, performing nearly as well as both the CCSD(T)/aug-CC-pVTZ and CCSD(T)/6-311+G(2df, 2p) models for small molecules and nearly as well as the latter for slightly larger ones. Broadly, all three models exhibit average absolute errors of ～3 kcal mol(-1) , and root mean square errors of ～4 kcal mol(-1) . The average signed error suggest that the OG2R3 approach systematically underbinds by ～2.3 kcal mol(-1) ; if this is used as a general correction, the approach performs as well or better than the pure CCSD(T) models. However, the OG2R3 model can be applied to molecules too large to be studied by the other CCSD(T) methods, as it requires only a fraction of the time and computer resources.     

Co3O4/CoO/Co/石墨复合材料的制备及其电容性能研究

以葡萄糖为前驱物,采用水热法合成了胶态碳球,然后利用胶态碳球制备了Co3O4/CoO/Co/石墨复合材料.此复合材料与其它研究者采用类似方法制备的物质相比具有完全不同的结构,它们是由多层不同物质组成的球形结构,其最外层是Co3O4,第二层是CoO,第三层是Co,最里面一层是石墨.采用循环伏安和恒电流充放电等方法对Co3...     

Structural characterization and in vivo evaluation of retinyl palmitate in non-ionic lamellar liquid crystalline system

Carrier systems for lipophilic drugs, such as the liquid crystalline systems (LCS) have been extensively studied to improve effect and selectivity. Retinyl palmitate (RP) is widely used in pharmaceutical and cosmetics products to improve the skin elasticity. The aim of this study was the development, characterization and the in vivo effectiveness of RP in non-ionic LCS structures. LCS containing polyether functional siloxane as oil phase, silicon glycol copolymer as surfactant and water in the ratio 30:10:60, with and without RP were studied. The results of the polarized light microscopy, small-angle X-ray scattering and rheology analysis indicated the presence of typical LCS structures with lamellar arrangement. Regardless of the presence of RP, the rheological studies showed the pseudo plastic behavior of the systems. However, highest hysteresis area was verified when comparing the system in the presence and in the absence of RP. Stability study SAXS monitored, carried out up to 30 days in various storage temperature conditions (25±2 °C, 37±2 °C and 5±2 °C) demonstrated the great structural stability of the LCS systems. The in vivo effectiveness analysis suggests that the RP-loaded LCS provided a significant reduction of the orbicular wrinkles in human volunteers (P=0.048).     

Degradation studies on segmented polyurethanes prepared with poly (d, l-lactic acid) diol, hexamethylene diisocyanate and different chain extenders

In order to investigate the effect of different chain extenders on degradation properties of segmented polyurethanes (SPUs), three types of segmented polyurethanes (SPU-P, SPU-O and SPU-A) based on poly (d, l-lactic acid) diol, hexamethylene diisocyanate (HDI), were synthesized with three chain extenders: peperazine (PP), 1, 4-butanediol (BDO) and 1, 4-butanediamine (BDA), respectively. Thermogravimetric analysis, activation energy and in vitro degradation were used to characterize the obtained polymers, quantitatively. The results revealed that chain extender played an important role in thermal degradation and biodegradation of polyurethanes. Thermogravimetric analysis and activation energy demonstrated that SPU-O, SPU-P and SPU-A presented best, second and weakest thermostability, respectively, and the thermal degradation mechanism of three SPUs was the same and regarded as a two-stage degradation. Data of hydrolytic degradation of the polymers during 12 weeks indicated that the in vitro degradation stability of SPU-A and SPU-P was similar, but both were better than that of SPU-O. The reason for the differences among three types of SPUs was discussed in this paper.     

Surface analysis of high performance carbon/bismaleimide composites exposed to electron irradiation

The aim of this article was to investigate the effects of electron irradiation in ultrahigh vacuum environment on the surface properties of high‐performance carbon/bismaleimide (BMI) composites used in aerospace. The changes in surface chemical composition with increasing irradiation fluence were studied by XPS. The evolution of surface morphology and surface roughness were observed by atomic force microscopy (AFM). The mass loss behavior occurring in the surface layer of the composites was examined. The results indicated that the electron irradiation in high vacuum caused rupture of chemical bonds and cross‐linking process in the surface layer, thereby leading to the mass loss behavior and the formation of carbonification layer in the surface of the carbon/BMI composites. The changes in the surface chemical composition were determined by a competing effect existing between the rupture of chemical bonds and the cross‐linking process at lower irradiation fluence, and by a degradation process only at higher fluence of electron irradiation. The surface morphology was altered and the surface roughness was increased significantly after electron irradiation. The mass loss ratio first increased obviously at lower fluences, and then reached a plateau value of 0.45% beyond 5 × 10¹⁵ cm^?2 fluence of electron irradiation. Copyright © 2011 John Wiley & Sons, Ltd.     

iPP/HDPE/CB复合材料的制备及反常的温度-电阻效应

本文利用普通熔融挤出法制备了iPP/HDPE/CB复合材料, 分别采用注射成型及压制成型方法得到测试试样. 通过研究复合材料体积电阻率随温度的变化, 考察注塑试样和压制试样的PTC特性及复合材料形态结构与试样PTC特性之间的关系.     

电泳沉积制备ZnO-C60和ZnO-MWCNT合涂层电极及其光电性质

在氧化铟锡( ITO)导电玻璃表面电泳沉积制备ZnO-C60和ZnO-MWCNT复合涂层电极,经后续热处理增强其结合强度,通过SEM观察2种电极复合涂层的表面形貌,并使用CHI 705电化学分析仪和PMI-E电致化学发光系统测定其光电性质.结果表明,ZnO-C60复合涂层电极具有较高的稳定性,在可见光辐照下,该电极显示...     

In vitro and in vivo antitumor activity of novel 3D-organotin supramolecular coordination polymers based on CuCN and pyridine bases

Two novel organotin supramolecular coordination polymers (SCP), namely, ³_∞[Me₃SnCu(CN)₂·(EN)₂], 1 and ³_∞[Ph₃SnCu(CN)₂·(3-mpy)₂], 2 are obtained by the reactions of K₃[Cu(CN)₄], ethyl nicotinate (EN) or 3-methylpyridine (3-mpy) and Me₃SnCl or Ph₃SnCl in H₂O/acetonitrile solution at room temperature. 2D-layers are constructed via H-bonds between the parallel 1D-puckered chains which contain nanometer-sized [-CN(R₃Sn)NC-] spacers connecting the tetrahedral (T-4) copper sites. The network structures of 1 and 2 consist of infinite layers connected by interlayer H-bonds forming 3D-framworks. 2 is the first compound in this family containing the Ph₃Sn cation. The electronic absorption spectra of 1 and 2 reveal a broad band at 320 nm due to CT transition while the emission spectra exhibit high energy bands at 400-460 nm due to metal-centered (MC) transitions and low energy bands at 485-530 nm corresponding to MLCT. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the in vitro antitumor effects of the SCP 1 and 2 on human breast cancer cell line, ZR-75-1. Cell cycle analysis revealed that the SCP 1 and 2 induced apoptosis in ZR-75-1 breast cancer cell line through activating caspase-3. Moreover, in vivo model, the compound SCP 2 suppressed tumor growth developed mammary carcinoma by 52.3%. Taken together, our novel compounds selectivity exhibit specific in vivo and in vitro antitumor effects.