Simultaneous Quantification of Puerarin and Daidzein in Rat Plasma by High-Performance Liquid Chromatography with Post-Column Modification and Fluorescence Detection

A sensitive HPLC method based on post-column modification and fluorescence detection has been developed for determination of puerarin and daidzein in rat plasma. Chromatographic separation was performed on a C₈ column with a linear gradient prepared from 0.5% aqueous acetic acid and 0.5% acetic acid in acetonitrile, delivered at a flow rate of 0.8 mL min⁻¹. Naringin was used as the internal standard. It was necessary to use acetic acid in the mobile phase to achieve good separation, but this led to fluorescence signal suppression, because puerarin and daidzein have native fluorescence at pH 8.0–9.0. To enhance the sensitivity, post-column modification with alkaline buffer was adopted. After this modification, detection sensitivity for puerarin and daizein increased more than 500-fold and 600-fold, respectively, compared with direct fluorescence detection. Signal-to-noise ratios for detection for puerarin were more than 150 times better than for UV detection after use of the same method of sample preparation. This sensitive analytical method was successfully used to determine pharmacokinetic data for puerarin and daidzein in rat plasma after oral administration of a single dose of Puerariae radix extract containing puerarin (approx. 8.4 mg) and daizein (approx. 5.9 mg) to male SD rats.     

Enzyme catalysis of insoluble cornstarch granules: Impact on surface morphology, properties and biodegradability

Granular cornstarch was treated with microbial glucoamylase (50 mM sodium acetate buffer at pH 5.5 at 30 °C, 150 rpm) for up to 8 h. Treated starch was recovered and evaluated for changes in granular morphology, chemical properties, thermal properties, crystallinity and impact on its biodegradability. As the enzyme treatment progressed, reducing sugars began to accumulate in the liquid culture media (total of 6% in 8 h) and the granule suffered roughly 6% weight loss within 8 h of incubation. While the granules appeared intact morphologically, numerous small pits developed throughout the surface of the granules as a result of the enzyme treatment. Even after 8 h of enzyme treatment, the pitted granules were not disrupted and remained intact. X-ray diffraction indicated no loss of crystallinity in the enzyme treated granules but rather an increase in relative crystallinity, suggesting that the enzyme preferentially catalyzed the anhydroglucose units in amorphous regions of the granule. These findings were further supported by FTIR data suggesting that granules become more resistant to enzyme attack as amorphous amylose is hydrolyzed faster than the crystalline amylopectin domains. These results also suggest that variations in the crystallinity of different types of starches have the potential to affect their rates of biodegradation. Enzyme treated starch granules exhibited resistance to biodegradation, and the degree of resistance was related to the length of enzyme treatment. Granules treated with enzyme for a total of 7 h and subjected to biodegradation in soil produced 40-50% less CO₂ in a closed circuit respirometer compared to the untreated samples. Differential scanning calorimetry (DSC) thermograms showed an endothermic reaction with little change in the onset and peak temperatures indicating that glucoamylase started by degrading the starch granules from the surface.     

丙烯酰胺与二(烯丙基)十二胺在羧甲基纤维素上的接枝共聚物合成与表征

以十二胺与 3 氯丙烯的反应物二 (烯丙基 )十二胺 (DALA)、丙烯酰胺 (AM)和羧甲基纤维素 (CMC)为原料 ,合成了疏水化水溶性两性纤维素接枝共聚物 (CGAL) .利用FTIR、1 H NMR、MS和元素分析 (EA)等方法确证了DALA的结构 .考察了CMC的取代度与浓度 ,AM、DALA与引发剂浓度 ,温度及pH等因素对接枝共聚的影响 .通过FTIR对CGAL进行了分析 .借助比色滴定、EA和GPC等手段测定了CGAL的组成与分子量 .TG分析和粘度法研究了CGAL及其溶液的热稳定性 .纤维素酶降解试验说明CGAL具有生物降解性     

聚对苯二甲酸丙二醇酯(PTT)的研究

新型聚酯材料聚对苯二甲酸丙二醇酯(PTT)是一种极有应用潜力的聚合物，但在非纤维领域的研究与应用才刚开始。本文简要概述了其发展状况；详述其结构、性能特点；重点介绍PTT目前在非纤维领域的应用与研究进展。     

A Comparison of PE Surfaces Modified by Plasma Generated Neutral Nitrogen Species and Nitrogen Ions

The surface modification of polyethylene (PE) by neutral nitrogen species (ground and excited state N₂ as well as atomic N; modified nitrogen plasma treatment) has been compared to the effect of nitrogen ion bombardment using X-ray Photoelectron Spectroscopy (XPS) and contact angle measurements. XPS results indicate that a greater nitrogen concentration was grafted during the modified nitrogen plasma treatment of PE, an effect that was attributed to surface sputtering during ion beam modification. The distribution of nitrogen-containing functionalities was strongly dependent upon the treatment strategy; the modified nitrogen plasma treatment lead predominantly to imine groups being formed at the PE surface, while amine groups were the dominant species produced during ion beam modification. The presence of electron irradiation during the modified nitrogen plasma treatment of PE did not modify the rate of nitrogen incorporation or change the nature of N-containing functional groups produced but did lead to a systematic decrease in contact angle.     

Mechanism and selectivity of 2,3-dimethyl-2,3-diphenylbutane mediated addition of vinyltriethoxysilane to polyethylene

The thermolysis of 2,3-dimethyl-2,3-diphenylbutane (bicumene) at temperatures ranging from 220 to 310 °C is used to initiate the radical-mediated graft addition of vinyltriethoxysilane (VTEOS) to polyethylene. Model hydrocarbon studies indicate that the cumyl radicals generated by the slow decomposition of bicumene are capable of direct hydrogen atom abstraction at levels that are sufficient to sustain a graft propagation sequence of high kinetic chain length. The interaction of O₂ with cumyl radicals can lead to oxidation of the initiator and the hydrocarbon substrate, thereby enhancing the macroradical population and improving grafting rates and yields. In addition to providing remarkable kinetic chain lengths for VTEOS additions, high-temperature bicumene-based processes can induce HDPE and LDPE fragmentation such that the effects of radical combination on melt viscosity are counteracted. As a result, alkoxysilane-modified polymers that moisture-cure efficiently can be produced without incurring the undesirable increases in molecular weight that accompany conventional grafting processes.     

Introduction of O-butyrylchitosan with a photosensitive hetero-bifunctional crosslinking reagent to silicone rubber film by radiation grafting and its blood compatibility

Based on an in vitro test for an improvement of the blood compatibility of silicone rubber (SR) films by grafting O-butyrylchitosan (OBCS), OBCS was covalently immobilized onto SR film surface using the photosensitive hetero-bifunctional crosslinking reagent, 4-azidobenzoic acid, which was previously bonded to OBCS by reaction between an acid group of the crosslinking reagent and a free amino group of OBCS. Surface properties of SR film were investigated by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), electron spectroscopy for chemical analysis (ESCA) and the water contact angle measurements. The blood compatibility of SR film was evaluated by platelet rich plasma (PRP) contacting experiments and the results were observed by scanning electron microscopy (SEM). The state of platelet adhesion was described. The suitable modifications could be carried out to tailor SR films biomaterial to meet the specific needs of different biomedical applications. These results suggest that the blood compatible of SR films/OBCS films show their suitability as potential biomaterials.     

表面修饰对贮氢电极电化学性能的影响

表面修饰对贮氢电极电化学性能的影响蔡称心（南京大学化学系南京２１００９３）王宝忱（中国科学院长春应用化学研究所）关键词：贮氢电极，Ｎｉ／ＭＨ电池，表面修饰Ｎｉ／ＭＨ（ＭｅｔａｌＨｙｄｒｉｄｅ）二次电池由于在放电容量、干净度、重金属污染、耐过充过放电能...     

Thermochemistry of hydride and phenyl groups on the surface of amorphous silicon dioxide

The thermodynamic properties of hydride and phenyl groups on the surface of amorphous silicon dioxide are investigated in the presented work. The characteristics of the surface silane centers (SiH) are determined from the data obtained by infrared spectroscopy and caloric measurements. The conversions of hydrogen and benzene with the surface are described by thermodynamic calculations at reactions take place in the gaseous phase.To model the reaction between hydrogen and the surface the thermodynamic data for (OH)_4−nSi_n (n=0-4) in the gaseous phase are used. The surface groups and the model molecules are comparable because the thermodynamic characteristics depend only from the local environment.The thermodynamic properties of (OH)₃SiC₆H₅ in the gaseous phase are determined to describe the reaction between benzene and the surface. The predications of these calculations are confirmed by the spectroscopic results. The properties of the surface phenyl groups (SiC₆H₅) are concluded from these data.     

Determination of nucleating ability ofwood for non-isothermal crystallisation of polypropylene

Composites made from an isotactic polypropylene matrix and wood (pine or beech) have been prepared and tested. To improve adhesion between components, the wood modification was performed by esterification with maleic, propionic, crotonic, succinic and phthalic anhydrides. The surface of wood fillers was also modified by chemical treatment with NaOH as well as by extraction process. Non-isothermal crystallisation of polypropylene in wood composites is studied by DSC, and the basic parameters of crystallisation are determined. We discovered that the composites containing chemical treated wood fillers showed the tendency reduction the nucleation efficiency of polypropylene. The ability of wood filler to induce nucleation in polypropylene matrix is dependent on the kind of chemical modification of surface wood