Effect of Polymer Concentration on Sustained Release Microparticles of Metformin Hydrochloride Prepared by Using Spray Dryer

Metformin hydrochloride, polyacrylic acid and β-cyclodextrin were taken for the preparation of spray dried sustained released micro particles in a different ratios. These sustained release micro particles were used for the preparation of tablets. Hardness of tablet increases with increase in concentration of polymer while the percentage friability decreases with increase in polymer concentration in tablet. The encapsulated drug shows better sustained release than the conventional tablet. The kinetics of the dissolution process were studied by analyzing the dissolution data using three kinetic equations—the zero-order equation, the first-order equation and the Hixson–Crowell cube root law equation.     

矿化度对疏水缔合聚合物溶液溶解时间的影响研究

疏水缔合聚合物是在亲水的聚丙烯酰胺大分子主链上引入少量疏水基团合成的新型水溶型聚合物。其有耐温耐盐的良好特性。但是疏水基的引入降低了聚合物的水溶性,增加了溶解时间。本文以渤海某油田地层水的离子构成作为参考,通过配制不同矿化度溶液来溶解疏水缔合聚合物,探索矿化度对疏水缔合聚合物溶液粘度及溶解时间的影响,并从原理上解释了出现这些现象的原因。最终发现,随着矿化度升高,疏水缔合聚合物溶液粘度降低,溶解时间增大。这种现象是由于矿化度升高,溶液中电解质增多,溶液极性增强,影响了疏水缔合聚合物分子的展开和缔结。     

Dissolution and rheological behaviour of hematite and quartz particles in aqueous media at pH 1

In this study we investigate isothermal, atmospheric acid dissolution behaviour of quartz and hematite minerals which constitute two of the predominant host gangue phases of typical low grade limonitic laterite ores. Batch dissolution tests were carried out on 57 wt.% solid dispersions for 4 h at pH 1 and 25 and 70 °C to establish the influential role of oxide mineralogy/chemistry on rheology and leaching behaviour. The results show that the two minerals displayed a weakly temperature and time-independent, non-Newtonian rheological behaviour with low shear yield stresses (<4 Pa) and viscosities (9–17 mPa s). Hematite dissolution rate was significantly higher compared with that of quartz under similar conditions. Quartz dissolution mechanism was substantially volume diffusion controlled at lower agitation rate (600 rpm) whilst for hematite it was both volume diffusion and chemical reaction controlled. These mechanisms reflected activation energies of 17.7 ± 0.9 and 28.5 ± 1.4 kJ/mol, respectively, for quartz and hematite. At 800 and 1000 rpm, dissolution of both minerals was chemical reaction-controlled with similar activation energies (32.6 ± 1.7 and 32.2 ± 1.6 kJ/mol). The findings underscore the need for higher agitation rates and elevated temperatures, to overcome both volume diffusion and chemical reaction limitations for enhanced acid leaching of these two fairly refractory oxides studied herein.     

盐酸吡格列酮的合成工艺研究

本文以如下合成路线为基础:羟基苯甲醛与2,4-噻唑烷二酮缩合后,经催化氢化,再与2-羟乙基-5-乙基吡啶磺酸酯对接,成盐得到盐酸吡格列酮,然后考察了催化氢化步骤中催化剂种类、用量、溶剂种类、反应温度和反应时间对反应收率的影响,从而找到了最适宜的催化氢化的反应工艺参数:催化剂为雷尼镍,催化剂用量为雷尼镍与中间体(5)的质量比为80%,溶剂为甲醇,反应温度为105℃,反应时间5h。找到了一个既能提高反应的收率,而且经济适用,适合工业化大生产的反应工艺。     

栀子大黄汤不同配伍对绿原酸溶出的影响

建立栀子大黄汤中绿原酸含量测定方法,比较不同配伍条件下绿原酸溶出差异,探寻溶出规律。Lichrospher C18(4.6 mm×250 mm,5μm)色谱柱,甲醇-0.5%乙酸,流速为1 m L/min,柱温30℃,检测波长:325 nm。栀子与大黄配伍后绿原酸溶出量较单味栀子增加33.33%,全方配伍后绿原酸溶出量则降低20.8%。复方配伍对绿原酸的溶出有一定的影响。     

The Effect of Ultrasound on the Dissolution of Pyrite Ores in Acidic and Fe2(SO4)3 Solutions

This paper deals with the investigation of the effect of ultrasonic energy on the dissolution of pyrite ores in acidic and Fe₂(SO₄)₃ solution. In the effect of ultrasound on the dissolution at various temperatures was experimentally investigated, while keeping the particle size and the solution concentration constant. The same experimental runs, without using ultrasound, were performed and the results were compared. According to these results, it was observed that ultrasound increased the conversion fraction by approximately 30 % compared with the experimental results without ultrasound.     

The Effect of Silver Chloride Formation on the Kinetics of Silver Dissolution in Chloride Solution

The precipitation and growth of AgCl on silver in physiological NaCl solution were investigated. AgCl was found to form at bottom of scratches on the surface which may be the less effective sites for diffusion or the favorable sites for heterogeneous nucleation. Patches of silver chloride expanded laterally on the substrate until a continuous film formed. The ionic transport path through this newly formed continuous film was via spaces between AgCl patches. As the film grew, the spaces between AgCl patches closed and ion transport was primarily via micro-channels running through AgCl patches. The decrease of AgCl layer conductivity during film growth were attributed to the clogging of micro-channels or decrease in charge carrier concentration inside the micro-channels. Under thin AgCl layer, i.e. on the order of a micrometer, the dissolution of silver substrate was under mixed activation-Ohmic control. Under thick AgCl layer, i.e. on the order of tens of micrometers, the dissolution of silver substrate was mediated by the Ohmic resistance of AgCl layer.     

离子液体在溶解方面的研究进展

离子液体作为一种新型的“绿色溶剂”,广泛应用于化学反应、萃取分离等化工过程。介绍了绿色溶剂——离子液体发展状况,详细讨论了离子液体在溶解方面的研究进展,包括离子液体在萃取分离方面的研究、离子液体作为反应过程中的溶剂以及离子液体作为高分子溶剂的研究。     

高聚物对陶瓷料浆性能的影响机理

本文根据陶瓷料浆的三种稳定机制（静电稳定机制、空间位阻稳定机制、空缺稳定机制）,详细阐述了高分子聚合物对浆料的不同作用机理,同时,从对陶瓷原料粒子表面改性的角度出发,介绍几种陶瓷粉体表面改性技术用以制备出稳定、均匀及高固相含量的陶瓷料浆。     

振动对聚合物机械性能影响的研究进展

本文综合地介绍了目前国内外振动对聚合物机构性能影响的研究进展,并且从分子运动、热 力学以及结晶的角度对影响的机理进行了分析,并对此研究的前景作了展望。     

Effect of Polymer Concentration on Autoclaved Cryogel Properties

Biomaterial sterilization is a prerequisite prior to patient's use, especially for scaffold implantation or injection. Various sterilization processes are mandated by the Food and Drug Administration including high‐pressure steam sterilization. Although high‐pressure steam or autoclave sterilization eliminates pathogens, it often leads to irreversible damages on soft materials such as hydrogels. In the current study, the impact of autoclave sterilization on cryogels made from several naturally‐derived polymeric precursors (alginate, hyaluronic acid, and gelatin) is analyzed. Specifically, the impact of polymer concentration on the structural and physical properties of autoclaved cryogels such as mechanics, swelling ratio, pore interconnectivity, and shape‐memory features is studied. The results demonstrate that at a given optimal polymer concentration, unique for each biopolymer investigated, autoclave sterilization does not substantially alter the microarchitectural or physical characteristics of cryogels, including their syringe injectability signature. In summary, when formulated under optimized polymer concentrations, autoclavable cryogels hold great potential for several biomedical applications, as they can be easily translated into clinical practice to benefit public health.     

聚合物电解质的研究进展

介绍了锂离子电池的特点、市场前景及聚合物锂离子电池的种类,综述了聚合物电解质的发展历程,重点阐述了近来研究较多的几种聚合物电解质的研究进展,包括:聚偏氟乙烯基(PVDF基)、聚丙烯腈基(PAN基)、聚甲基丙烯酸甲酯基(PMMA基)和聚乙烯类(PE)聚合物电解质。     

Role of Polymer Concentration and Crosslinking Density on Release Rates of Small Molecule Drugs

Over the past few years, researchers have demonstrated the use of hydrogels to design drug delivery platforms that offer a variety of benefits, including but not limited to longer circulation times, reduced drug degradation, and improved targeting. Furthermore, a variety of strategies have been explored to develop stimulus-responsive hydrogels to design smart drug delivery platforms that can release drugs to specific target areas and at predetermined rates. However, only a few studies have focused on exploring how innate hydrogel properties can be optimized and modulated to tailor drug dosage and release rates. Here, we investigated the individual and combined roles of polymer concentration and crosslinking density (controlled using both chemical and nanoparticle-mediated physical crosslinking) on drug delivery rates. These experiments indicated a strong correlation between the aforementioned hydrogel properties and drug release rates. Importantly, they also revealed the existence of a saturation point in the ability to control drug release rates through a combination of chemical and physical crosslinkers. Collectively, our analyses describe how different hydrogel properties affect drug release rates and lay the foundation to develop drug delivery platforms that can be programmed to release a variety of bioactive payloads at defined rates.     

超声波对微流道中聚合物流动性能的影响研究

为了研究超声波作用下的聚合物材料流动性能及其影响因素,利用自主开发的聚合物超声波辅助挤出测试系统,进行了超声波作用下聚合物熔体在微流道管壁的剪切力、剪切速率和表观黏度的测试,并在与传统稳态挤出相比较基础上,分析了超声波对微流道中聚合物熔体流动性能的影响。实验结果表明,引入超声振动后,微流道的入口压力降有明显降低,并且随着熔体剪切速率的增加而增大;超声振动作用下聚合物熔体剪切速率存在临界值,当剪切速率小于临界值时,超声下聚合物黏度小于传统稳态挤出聚合物黏度,反之,超声聚合物黏度大于传统挤出聚合物黏度。     

聚丙烯酸丁酯阴离子聚体和聚苯乙烯阳离子聚体共混物及相容性的研究

本文利用动态粘弹谱对一系列丙烯酸丁酯／丙烯酸阴离子聚体和苯乙烯／４－乙烯基吡啶阳离子聚体的共混相容性进行了研究。研究结果表明：两者的相容性与各自所含的离子浓度有关，当其离子浓度大于１１％时，可达到完全相容的程度。     

曝氧量对污水聚合物黏度影响的室内实验研究

随着我国东部老油田含水率逐年自然上升,产出污水既造成了环境破坏,又导致资源的浪费,因此,使用采出污水配制聚合物溶液进行回注的技术被各大油田广泛使用。而如今普遍使用的污水曝氧技术,虽然能够减小甚至消除污水中厌氧细菌对聚合物分解所造成的溶液黏度降低,但是过度的曝氧也会引起聚合物分子链发生断裂,从而减低溶液的黏度。采用室内实验,采用曝氧污水及厌氧污水配制聚合物溶液的方法,研究氧分子对于聚合物溶液黏度以及稳定性的影响。实验结果发现,使用曝氧污水所配制聚合物溶液的黏度要高于使用厌氧污水所配制聚合物溶液的黏度,在此基础上确定污水最佳曝氧浓度约为5 mg/L。     

Nonlinear Rheology of Unentangled Polymer Melts Reinforced with High Concentration of Rigid Nanoparticles

A scaling model is presented to analyze the nonlinear rheology of unentangled polymer melts filled with high concentration of small spherical particles. Assuming the majority of chains to be reversibly adsorbed to the surface of the particles, we show that the emergence of nonlinearity in the viscoelastic response of the composite system subjected to a 2D shear flow results from stretching of the adsorbed chains and increasing desorption rate of the adsorbed segments due to the imposed deformation. The steady-state shear viscosity of the mixture in nonlinear shear thinning regime follows the power law h ~ [(g)\dot] ^{- 1/2} , \eta \sim \dot{\gamma }^{ - 1/2} , where [(g)\dot] \dot{\gamma } is the applied shear rate. At large strain amplitude γ_0, the storage and loss moduli in strain sweep tests scale as G^￠ ~ g₀ ^{- 1} G^{\prime}\sim \gamma_{0}^{ - 1} and G^￠￠ ~ g₀ ^{- 1/2} , G^{\prime\prime}\sim \gamma_{0}^{ - 1/2} , respectively.     

振动应力场对均相体系中聚合物结晶行为的影响

以研究压力振动应力场对均相体系中聚合物结晶行为的影响效果为目的，通过对HDPE、PP材料的振动试样的WAXD、DSC、SEM分析结果进行对比发现，振动应力场促进了均相体系聚合物的结晶，振动试样的结晶度明显提高，结晶晶粒明显细化，晶粒更加细密。     

Mathematical Model of the Dissolution Stage in Cooling Batch Crystallization

Abstract

Experiments were performed in a cooling batch crystallizer to develop a phenomenological model that represents the dissolution stage in crystallization. Two models were used: a theoretical and a black box, comparing their results with the experimental ones through the simulation of these models (use the mean and the standard deviation of crystal size like comparative means). The theoretical model was obtained by population's balance, mass and energy balances, and constitutive relations (decrease speed and production‐reduction speed). The black box model consisted of a set of equations, which are functions of the mean, standard deviation, agitation speed and time.     

溶度参数对聚α-烯烃油溶剂选择的影响

以溶度参数为溶剂选择依据,对α-癸烯齐聚制备润滑油基础油合成实验的溶剂进行研究.考察了不同溶度参数的溶剂对PAO的影响.将溶度参数的概念引入聚合反应溶剂的选择中.结果表明,溶剂种类对PAO的影响明显.由于环己烷的溶度参数接近聚合物,可作为聚α-烯烃油的理想溶剂.产物收率高,性能优良.