添加剂对PVDF膜结构和性能的影响

以亲水性的聚乙二醇(PEG)和聚乙烯吡咯烷酮(PVP)为添加剂,利用浸没沉淀相转化法制备聚偏氟乙烯(PVDF)多孔膜。利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅立叶-红外光谱仪(FT-IR)对所制得膜进行表征测试,分析了添加剂对膜孔结构、结晶度和膜性能的影响。结果表明:添加剂能有效改善膜的孔径结构,使得膜的微孔增多、孔间连通性增强、膜结晶度降低,达到提高膜的纯水通量和孔隙率的效果。     

紫外分光光度法测定氯氟吡氧乙酸十二酯的研究

以甲醇作为溶剂,用紫外分光光度法测定氯氟吡氧乙酸十二酯的含量,测得氯氟吡氧乙酸十二酯对照品溶液浓度在12.0～20.0μg/mL范围之内线性关系良好,其线性方程为A=0.0815C+0.0318(R2=0.9832).平均回收率为90.86%,RSD为5.3%(n=6),结果说明方法简便、灵敏、准确,重现性好.     

校准蒸发光散射检测器选用标准物质的比较与分析

通过对葡萄糖和三氯蔗糖的物理、化学性质的比较,采用高效液相色谱仪和蒸发光散射检测器进行标准溶液色谱峰面积的检测,并用G rubbs检验法对其数据进行异常值检验。结果表明,三氯蔗糖相对于葡萄糖较为稳定,选用三氯蔗糖作为蒸发光检测器校准用标准物质比较合适。     

Facile assembly of size- and shape-tunable IV-VI nanocrystals into superlattices

In comparison to the previous lengthy approaches, we described a general and simple strategy for engineering the superlattice assembly of IV-VI semiconductor nanocrystals (NCs) with tunable sizes and morphologies. Not only the well-studied spherical NCs but also some special-shaped NCs, such as the quasi-cubic, cubic, truncated octahedral, and octahedral, could self-assemble into well-ordered patterns, as demonstrated in PbS, PbSe, and PbTe. These results extended our proposed model about the configuration of ligand chains in the superlattice assembly. This powerful capability of assembling superlattices was dominated by a heat-treatment process, providing a significant and extensive direction in the engineering of morphology-tunable NC superlattices.     

In vitro model on glass surfaces for complex interactions between different types of cells

This report establishes an in vitro model on glass surfaces for patterning multiple types of cells to simulate cell-cell interactions in vivo. The model employs a microfluidic system and poly(ethylene glycol)-terminated oxysilane (PEG-oxysilane) to modify glass surfaces in order to resist cell adhesion. The system allows the selective confinement of different types of cells to realize complete confinement, partial confinement, and no confinement of three types of cells on glass surfaces. The model was applied to study intercellular interactions among human umbilical vein endothelial cells (HUVEC), PLA 801 C and PLA801 D cells.     

Enhanced poling efficiency in rigid-flexible dendritic nonlinear optical chromophores

Naringenin is a flavonoid specific to citrus fruits and possesses anti-inflammatory, anticarcinogenic, and antitumour effects. But due to a lower half-life and rapid clearance from the body, frequent administration of the molecule is required. To improve the bioavailability and prolong its duration in body system, its phospholipid complexes were prepared by a simple and reproducible method. Naringenin was complexed with phosphatidylcholine in equimolar ratio, in presence of dichloromethane. The prepared Phytosomes (naringenin–phospholipid complex) were evaluated for various physical parameters like FT-IR spectroscopy, Differential Scanning Calorimetry (DSC), X-ray powder diffractometry (XRPD), Solubility, Scanning Electron Microscopy (SEM) and the in vitro drug release study. These phospholipid complexes of naringenin were found to be irregular and disc shaped with rough surface in SEM. Drug content was found to be 91.7% (w/w). FTIR, ¹H NMR, DSC and XRPD data confirmed the formation of phospholipid complex. Water solubility of naringenin improved from 43.83 to 79.31 μg/mL in the prepared complex. Unlike the free naringenin (which showed a total of only 27% drug release at the end of 10 h), naringenin complex showed 99.80% release at the end of 10 h of dissolution study. Thus it can be concluded that the phospholipid complex of naringenin may be of potential use for improving bioavailability.     

The Behavior of an Improved RP-18 Sintered Plate in Planar Electrochromatography

JPC – Journal of Planar Chromatography – Modern TLC - After much improvement of a new type of RP-18 sintered plate, mobile phase could be successfully used in planar...     

Preactivation‐Based,One‐Pot Combinatorial Synthesis of Heparin‐like Hexasaccharides for the Analysis of Heparin–Protein Interactions

Heparin (HP) and heparan sulfate (HS) play important roles in many biological events. Increasing evidence has shown that the biological functions of HP and HS can be critically dependent upon their precise structures, including the position of the iduronic acids and sulfation patterns. However, unraveling the HP code has been extremely challenging due to the enormous structural variations. To overcome this hurdle, we investigated the possibility of assembling a library of HP/HS oligosaccharides using a preactivation‐based, one‐pot glycosylation method. A major challenge in HP/HS oligosaccharide synthesis is stereoselectivity in the formation of the cis‐1,4‐linkages between glucosamine and the uronic acid. Through screening, suitable protective groups were identified on the matching glycosyl donor and acceptor, leading to stereospecific formation of both the cis‐1,4‐ and trans‐1,4‐linkages present in HP. The protective group chemistry designed was also very flexible. From two advanced thioglycosyl disaccharide intermediates, all of the required disaccharide modules for library preparation could be generated in a divergent manner, which greatly simplified building‐block preparation. Furthermore, the reactivity‐independent nature of the preactivation‐based, one‐pot approach enabled us to mix the building blocks. This allowed rapid assembly of twelve HP/HS hexasaccharides with systematically varied and precisely controlled backbone structures in a combinatorial fashion. The speed and the high yields achieved in glycoassembly without the need to use a large excess of building blocks highlighted the advantages of our approach, which can be of general use to facilitate the study of HP/HS biology. As a proof of principle, this panel of hexasaccharides was used to probe the effect of backbone sequence on binding with the fibroblast growth factor‐2 (FGF‐2). A trisaccharide sequence of 2‐O‐sulfated iduronic acid flanked by N‐sulfated glucosamines was identified to be the minimum binding motif and N‐sulfation was found to be critical. This provides useful information for further development of more potent compounds towards FGF‐2 binding, which can have potential applications in wound healing and anticancer therapy.     

Three New Sesquiterpenoids from Echinops ritro L.

From the whole plants of E. ritro L., the three new sesquiterpenoids (3α,4α,6α)‐3,13‐dihydroxyguaia‐7(11),10(14)‐dieno‐12,6‐lactone ( 1 ), (3α,4α,6α,11β)‐3‐hydroxyguai‐1(10)‐eno‐12,6‐lactone ( 2 ), and (11α)‐11,13‐dihydroarglanilic acid methyl ester (=(4β,6α,11α)‐4,6‐dihydroxy‐1‐oxoeudesm‐2‐en‐12‐oic acid methyl ester; 3 ), together with eight known sesquiterpenoids, were isolated. Their structures were elucidated through analysis of spectroscopic data including extensive 2D‐NMR.     

Theoretical prediction on HBeN− and HNBe− anions using multiconfiguration second‐order perturbation theory

The HBeN^? and HNBe^? anions have been investigated for the first time using the CASSCF, CASPT2, and DFT/B3LYP methods with the contracted atomic natural orbital (ANO) and cc‐pVTZ basis sets. The geometries of all stationary points along the potential energy surfaces were optimized at the CASSCF/ANO and B3LYP/cc‐pVTZ levels. The ground and the first excited states of HBeN^? are predicted to be X²Π and A²Σ⁺ states, respectively. It was predicted that the ground state of HNBe^? is X²Σ⁺ state. The A²Π state of HNBe^? has unique imaginary frequency. A bend local minimum M1 was found along the 1²A″ potential energy surface and the A²Π state of HNBe^? should be the transition state of the isomerization reactions for M1 ? M1. The CASPT2/ANO potential energy curves of isomerization reactions were calculated as a function of HBeN bond angle. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010