Structural and kinetic aspects of hydrostatic pressure effect on polymer network formation

Abstract

Effect of hydrostatic pressure up to 250 MPa on structurization kinetics and morphology of network polymers based on epoxy oligomers has been studied using the methods of measurements of volume resistivity and optical microscopy.     

Synthesis and Characterization of Fumarate Copolyesters for Use in Bioresorbable Bone Cement Compositions

Unsaturated amorphous copolyesters of varied composition were prepared by transesterification copolymerization of diethyl fumarate, and two diols, 1,2‐propanediol and 2‐methyl‐1,3‐propanediol. The copolyesters were characterized by IR, ¹H‐ and ¹³C‐NMR, GPC, DSC, and TGA. The glass transition is changing with composition from 0°C to 19°C as the content of 1,2‐propanediol residue in the copolyester increases. The copolyester structure and composition have an impact on the compressive strength and hydrolytic stability of the composites prepared by crosslinking the fumarate double bonds with N‐vinyl pyrrolidone in the presence of inorganic filler, calcium sulfate dihydrate, with the addition of a radical initiator, benzoyl peroxide, at ambient temperatures.     

基于营养成分和主成分分析的驴肉与其他肉类分类研究

选取生鲜驴肉样品40个,生鲜猪肉、牛肉、羊肉样品各8个,使用索氏抽提法和凯氏定氮法分别检测了样品的肌间脂肪和蛋白质含量,采用气相色谱法检测了样品的多种脂肪酸,并使用阳离子交换色谱分离、茚三酮柱后衍生法对样品的多种氨基酸含量进行了检测.对驴肉和其他肉类样品的多种营养成分含量进行了单因素方差分析. 结果发现:脂肪、蛋白质、肉豆蔻酸、十五碳酸、棕榈酸、棕榈油酸、硬脂酸、亚油酸、油酸及总不饱和脂肪酸、总饱和脂肪酸具有极显著差异,二十四碳一烯酸、反式油酸、苏氨酸、丝氨酸、异亮氨酸、亮氨酸、赖氨酸、组氨酸和脯氨酸具有显著差异,门冬氨酸、谷氨酸、甘氨酸、丙氨酸、酪氨酸、精氨酸和总氨基酸具有一定差异.对不同差异水平指标组合分别进行了主成分分析,发现有明显的聚类趋势,其中极显著差异指标数据(多为风味成分)能够完全将驴肉和其他肉类分开.研究结果表明:使用营养成分对驴肉和其他肉类进行分类是可行的,不同肉类所具有的不同风味特征是分类的关键.     

兰香草精油化学成分的研究

采用常压水蒸气蒸馏法提取了兰香草挥发油，得油率为0．35％～0．52％．其相对密度为(20℃)0．9980～0．9900，折射率为(20℃)1．4608，比旋光度为 0．51^*，酸值为1．5，并用毛细管气相色谱、红外光谱、核磁共振谱和色-质联机等对该挥发油进行了系统的成分分析．在分出的112个色谱峰中，共鉴定出71个化合物，占挥发油总量的94．6％．其主要成分为芳樟醇、紫苏醇、香芹酮、荠芋烯、4-甲基-6-庚烯-3-酮、菉草烯、马鞭草烯酮、左旋松香芹酮、2-壬烯-4-炔等。     

Gap-free compositions and gap-free samples of geometric random variables

We study the asymptotic probability that a random composition of an integer n is gap-free, that is, that the sizes of parts in the composition form an interval. We show that this problem is closely related to the study of the probability that a sample of independent, identically distributed random variables with a geometric distribution is likewise gap-free.     

The impact of damming on geochemical behavior of dissolved inorganic carbon in a karst river

To determine the impact of damming on the geochemical behavior of dissolved inorganic carbon （DIC） in the Wujiang River basin, field measurements and samples were collected semimonthly for a year. The surface waters of the reservoirs contained concentrations of chlo- rophyll a up to 5.6 times higher than the upstream river. Compared with the entering waters, the contributions of HCO3- and dissolved CO2 to DIC decreased, and the contribution of CO32- to DIC and the carbon isotopic composition of DIC （δ13CDIc） increased in the surface waters of the reservoirs, while in the waters released, the DIC species showed reverse geochemical behaviors. The δ13CDIc ranged from -10.2 %o to 2.5 %0, indicating that significant contributions were from carbonate weathering, photosynthesis, and respiration. After the damming of a river, the bioactivity of phytoplankton was enhanced, and this affected the geochemistry of DIC compared to an unimpacted river and δ13CDIC can be used to discern these changes. High-frequency monitoring of river-reservoir systems is necessary to evaluate the efflux of CO2 and provide a better understanding of the carbon sinks and sources in the impounded river.     

武陵山地区特色药用植物七叶一枝花的研究与应用

本文就武陵山山区特色植物七叶一枝花的形态特征、化学成分、药理活性、临床应用、遗传多样性等进行了综述,并针对七叶一枝花的资源现状及其亟待解决的问题进行探讨,旨在为深入研究和开发利用七叶一枝花奠定基础.     

Surface Laser Sintering of exothermic powder compositions

This work reports the temperature behavior associated with formation of new metal-polymer, intermetallic, and ceramic materials by Selective Laser Sintering. Here, experimental data produced from temperature measurements for inert as well as reaction powder compositions and the combustion wave front is reported. Analysis using an analog-digital-analog computer converter allowed some control of laser movement and hence some control of the exothermal reaction — in so doing it provided near optimum conditions for forming layered 3D articles.     

Hydrothermal Synthesis of Mixed Oxide Compositions of Cobalt-Zirconium and their Catalytic Activity in the Decomposition of Hydrogen Peroxide

The article presents the results of research on the hydrothermal synthesis of nanoscale oxide of cobalt and zirconium and their mixed oxide compositions. The synthesized samples have been characterized by the X-ray phase, scanning electron microscopy and nitrogen adsorption-desorption methods; the composition of the samples has been determined by chemical analysis methods, and their catalytic activity in the decomposition of hydrogen peroxide has been studied. It has been shown that during synthesis, highly dispersed cobalt and zirconium oxide are formed, and the sample of the composition (mol %): Co₃O₄(88)−ZrO₂(12) has the highest specific surface area (181.2 m²/g) and the highest activity (K=6.18 ⋅ 10⁻² s⁻¹) against the decomposition of hydrogen peroxide. The increasing of the ZrO₂ content in oxide compositions reduces their catalytic activity. The particle size in the synthesized samples is 7–38 nm.     

Evaluation and comparison of mid-infrared,Raman and near-infrared spectroscopies for characterization and determination of the compositions in fully biodegradable poly(lactic acid)/poly(propylene carbonate)/poly(butylene adipate-co-terephthalate) blends combined with chemometrics

In this work, mid-infrared (MIR), Raman and near-infrared (NIR) spectroscopies were evaluated and compared for characterization and determination of the compositions in poly(lactic acid)/poly(propylene carbonate)/poly(butylene adipate-co-terephthalate) (PLA/PPC/PBAT) blends via chemometrics. Qualitative analysis of MIR, Raman, and NIR spectra of the three compositions was performed. Partial least squares (PLS) models were developed based on each spectroscopy for quantitative determination of the concentrations. The data suggested that MIR and Raman have an advantage over NIR in terms of qualitative recognition of the three compositions. The data also showed that Raman and NIR succeeded in determining the concentrations, while the concentration determined via MIR was inaccurate. Hence, Raman is the optimal analytical tool for qualitative characterization and quantitative determination of the compositions in fully biodegradable PLA/PPC/PBAT blends. The characteristic bands in the Raman spectra clearly identify PLA, PPC, and PBAT to be 392 cm^?1 (δ CCO), 948 cm^?1 (ν C?O?C) and 1600 cm^?1 (ν C ? C in benzene ring), respectively. The optimal calibration models based on Raman for PLA, PPC, and PBAT exhibited root mean square error of prediction (RMSEP) values of 3.140%, 3.576%, and 2.538%, respectively.