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.     

Sorption and desorption properties of a CaH2/MgB2/CaF2 reactive hydride composite as potential hydrogen storage material

The hydrogenation behavior of 3CaH₂+4MgB₂+CaF₂ composite was studied by manometric measurements, powder X-ray diffraction, differential scanning calorimetry and attenuated total reflection infrared spectroscopy. The maximum observed quantity of hydrogen loaded in the composite was 7.0 wt%. X-ray diffraction showed the formation of Ca(BH₄)₂ and MgH₂ after hydrogenation. The activation energy for the dehydrogenation reaction was evaluated by DSC measurements and turns out to be 162±15 kJ mol⁻¹ H₂. This value decreases due to cycling to 116±5 kJ mol⁻¹ H₂ for the third dehydrogenation step. A decrease of ca. 25–50 °C in dehydrogenation temperature was observed with cycling. Due to its high capacity and reversibility, this composite is a promising candidate as a potential hydrogen storage material.     

Development and validation of a GC-MS method for rapid determination of galanthamine in Leucojum aestivum and Narcissus ssp.: a metabolomic approach

Galanthamine, an acetylcholinesterase inhibitor marketed as a hydrobromide salt for the treatment of Alzheimer's disease, is obtained from some Amaryllidaceae plants. A new method was developed and validated for its quantification by GC-MS in different plant sources: bulbs and leaves from Narcissus confusus; bulbs from N. pseudonarcissus cv. Carlton; and leaves and in vitro cultures from L. aestivum. Samples (50 mg) were extracted with methanol (1 mL) for 2 h, then aliquots of the extracts were silylated and analyzed by GC-MS. The calibration line was linear over a range of 15-800 μg galanthamine/sample, ensuring an analysis of samples with a content of 0.03-1.54% analyte referred to dry weight. The recovery was generally more than 95%. Good inter- and intra assay precision was observed (RSD < 3%). Principal component analysis of GC-MS chromatograms allowed discrimination of the plant raw material with respect to species, organs and geographical regions. The analytical method developed in this study proved to be simple, sensitive and far more informative than the routine analytical methods (GC, HPLC, CE and NMR), so it may be useful for quality control of plant raw materials in the pharmaceutical industry.     

Gemifloxacin mesylate (GFM) stability evaluation applying a validated bioassay method and in vitro cytotoxic study

The validation of a microbiological assay applying the cylinder-plate method to determine the quinolone gemifloxacin mesylate (GFM) content is described. Using a strain of Staphylococcus epidermidis ATCC 12228 as the test organism, the GFM content in tablets at concentrations ranging from 0.5 to 4.5 μg mL⁻¹ could be determined. A standard curve was obtained by plotting three values derived from the diameters of the growth inhibition zone. A prospective validation showed that the method developed is linear (r = 0.9966), precise (repeatability and intermediate precision), accurate (100.63%), specific and robust. GFM solutions (from the drug product) exposed to direct UVA radiation (352 nm), alkaline hydrolysis, acid hydrolysis, thermal stress, hydrogen peroxide causing oxidation, and a synthetic impurity were used to evaluate the specificity of the bioassay. The bioassay and the previously validated high performance liquid chromatographic (HPLC) method were compared using Student's t test, which indicated that there was no statistically significant difference between these two validated methods. These studies demonstrate the validity of the proposed bioassay, which allows reliable quantification of GFM in tablets and can be used as a useful alternative methodology for GFM analysis in stability studies and routine quality control. The GFM reference standard (RS), photodegraded GFM RS, and synthetic impurity samples were also studied in order to determine the preliminary in vitro cytotoxicity to peripheral blood mononuclear cells. The results indicated that the GFM RS and photodegraded GFM RS were potentially more cytotoxic than the synthetic impurity under the conditions of analysis applied.