Evaluation of rate of swelling and erosion of verapamil (VRP) sustained-release matrix tablets

Tablets manufactured in-house were compared to a marketed sustained-release product of verapamil to investigate the rate of hydration, erosion, and drug-release mechanism by measuring the wet and subsequent dry weights of the products. Swelling and erosion rates depended on the polymer and granulating fluid used, which ultimately pointed to their permeability characteristics. Erosion rate of the marketed product was highest, which suggests that the gel layer that formed around these tablets was weak as opposed to the robust and resistant layers of test products. Anomalous and near zero-order transport mechanisms were dominant in tests and commercial product, respectively.     

Milling of rice grains: The roles of starch structures in the solubility and swelling properties of rice flour

Rice flours with different particle sizes and degrees of damaged starch granules were produced by hammer milling and cryogenic milling of rice grains, where degradation of starch molecules was evident in the hammer‐milled flours, but not in the cryogenically milled flours. The solubility and swelling properties of the resulting rice flours were determined in cold (30°C) and hot water (90°C). The cold‐ and hot‐water starch solubility was strongly correlated with the degree of damaged starch granules, and weakly with the particle size of rice flour. No evident correlations were observed between starch solubility and the molecular structures, indicating that molecular degradation by milling process was not the only precondition of increased starch solubility. Possible mechanism for the observed correlations is that increasing surface area and/or exposure of loosely packed inner part of starch granules with increasing degree of damaged starch granules allowed more starch molecules to leach out in cold and hot water. Furthermore, the cold‐water swelling of rice flour was strongly correlated with the degree of damaged starch granules, possibly due to the rapid hydration of damaged starch granules, whereas the hot‐water swelling did not show any correlations with flour particle size and granular and molecular starch structures. The results have provided better insights in the relationship between starch structures and solubility and swelling properties of rice flour, which can be used to improve the manufacture and selection criteria of rice flour for better products.     

W/O/W emulsions with high internal droplet volume fraction

We prepared water-in-oil-in-water (W/O/W) double emulsions with high internal aqueous droplet fraction using food-based ingredients. These compartmentalised materials were comprised of oil globules dispersed in an external aqueous phase, with the globules themselves containing densely packed inner aqueous droplets. We were able to obtain double emulsions with large globule fractions (up to 45 vol.%) using only 5 vol.% oil (relative to the overall composition). In the final state, the inner droplet fraction within the globules could exceed 90 vol.%. The method was based on two successive emulsification steps, followed by osmotic swelling (transport of water from the external phase to the inner droplets through the oil phase). During the final step, the swelling was controlled by the osmotic pressure mismatch between the external and internal aqueous phases using solutes dissolved at different concentrations. The osmotic swelling model of Mezzenga et al. (Langmuir, 2004, 20, 3574-3582) was re-adapted in the limit of small Laplace pressures to predict the final composition resulting from osmotic equilibration. The internal droplet fraction was lower than that predicted by the model as a consequence of coalescence phenomena occurring during the swelling process. The proposed approach constitutes a valuable guide within the prospect of formulating emulsions with enhanced encapsulation capacity and reduced fat content.     

橡胶材料对甲醇汽油的抗溶胀性研究

甲醇作为一种性能优良的替代燃料,其对橡胶材料具有很大的溶胀危害,这在很大程度上制约了甲醇汽油的发展。选取汽车上常用的几种橡胶材料分别进行汽油和甲醇汽油的溶胀试验,分析出可用于甲醇汽油上的抗溶胀性较好的橡胶材料。     

温度和pH值对智能水凝胶溶胀行为的影响

以N-马来酰化壳聚糖(N-MACH)为交联剂,N-异丙基丙烯酰胺(NIPAAm)为单体,羧甲基纤维素钠(CMC)为半互穿材料,分别合成了PNIPAAm和PNIPAAm/CMC半互穿网络智能水凝胶,研究了两种水凝胶在不同温度的去离子水和不同pH值的缓冲溶液中的溶胀现象,结果表明介质温度和pH值对水凝胶的溶胀行为有显著影响。在温度和pH值一定时,水凝胶的溶胀率随着交联剂用量的增加而下降,随着CMC用量的增加而上升。     

Amaranth starch-rich fraction properties modified by high-temperature heating

The effect of high-temperature fluidized-bed heating on some properties of an amaranth high-starch fraction obtained from Amaranthus cruentus grains was evaluated. A two-factor at three levels factorial experimental design (3²) was adopted, one factor being the heating temperature (190, 200 and 210 °C) and the other, the moisture content of the high-starch fraction (12%, 16% and 20% wet basis). The effects on the responses water solubility, swelling power, amylographic and dynamic responses, crystallinity degree and gelatinization enthalpy were established by using response surface methodology. A partial loss of starch crystalline structure was observed but most of their granular integrity was preserved. As temperature and moisture increased, loss of crystalline structure and degree of gelatinization also increased. The obtained amaranth high-starch flours were of a solid character at low temperature, with high consistency when cooked and low water solubility, which make them suitable for industrial applications.     

泥页岩水化膨胀测定新方法

介绍了使用WLZ-1膨胀仪测定泥页岩水化膨胀的新方法,通过测定同种相同质量具有不同初始体积样品的膨胀终了体积,建立了膨胀终了体积与初始体积间的函数关系式,借助于该函数关系式,可排除样品中孔隙体积的干扰,计算出无孔隙样品膨胀终了体积。利用该方法能够测定由于泥页岩中粘土矿物层间水化膨胀造成的泥页岩体积的总膨胀量,更真实地反映泥页岩水化膨胀能力。     

条形药包端部加药高速摄影试验研究

本文介绍了应用高速摄影技术进行条形药包端部加药的试验研究。通过对条形药包端部加药后鼓包运动速度的分析研究,证明了端部加药及加药量对条形药包爆炸能量的瞬间作用力、爆炸能量分布和端部能量损失的作用。     

泥页岩膨胀动力学研究方法初探

介绍了智能膨胀仪、WLZ型膨胀仪的仪器结构及性能特点,并用这两种膨胀仪建立动力学曲线,并介绍了泥页岩膨胀动力学曲线的概念、测定方法、测定步骤和实验结果处理。根据求出的膨胀动力学方程和膨胀速度方程可以计算并比较实验样品在不同膨胀介质中的膨胀量和膨胀速度,并确定膨胀周期,从而优选出最佳的钻井液体系和配方,指导现场钻井液处理。     

Effect of Nano–Magnesium Hydroxide on Mechanical and Flame-Retarding Properties of SBR and PBR: A Comparative Study

Magnesium hydroxide [Mg(OH)₂] is one of the potential inorganic fillers. In this work, nanoparticles (37±5 nm) of the magnesium hydroxide were prepared using matrix-mediated growth and control technique, and their size was confirmed by X-ray diffraction technique. Nano-Mg(OH)₂-SBR and nano-Mg(OH)₂-PBR composites with 2–10% (w/w) filler loading were prepared by compounding on laboratory-scale two-roll mill and a compression molding machine. These composites were tested for tensile and physical properties, and the properties were compared with the composites of commercial Mg(OH)₂. The incorporation of nanofiller improved the properties of nanocomposites.