DIFFUSIONAL RELEASE OF WATER-SOLUBLE BIOACTIVE AGENTS FROM ETHYLENE-VINYL ACETATE COPOLYMERS

A model is presented for the diffusional release of theophylline and albumin from ethylene-vinyl acetate based polymeric systems with dynamically changing porosity. The model may be used to predict values of tortuosity of certain types of controlled drug delivery polymeric systems if drug dissolution limitations are negligible. The values of the tortuosity factor calculated indicate that small constrictions between large pores play an important role in the solute release behavior from these samples.     

包覆NIPAM—ODA双亲共聚物的脂质体的温控释放行为

为了研究对温度敏感的双亲性共聚物包覆的脂质体的温控释放行为,合成了Ｎ－异丙基丙烯酰胺（ＮＩＰＡＭ）和丙烯酸十八酯（ＯＤＡ）的共聚物。利用荧光探针法研究了共聚物水溶液随温度升高时出现的ＬＣＳＴ现象,表明该高分子在温度升高到３０℃以上时存在着明显的相分离行为。     

乙烯-醋酸乙烯热熔胶对水泥基材料裂缝自修复性能的影响

将乙烯-醋酸乙烯(ethylene-vinyl acetate,EVA)作为修复组分掺入到水泥基材料中,制备成具有裂缝自修复功能的水泥基复合材料。研究了水泥基材料裂缝自修复过程中采用热熔胶技术路线的可行性和含热熔胶的水泥基材料的裂缝自修复性能。结果表明:预损伤30%,50%和70%的试件,经EVA热熔胶修复后抗折强度均超过原始试件。EVA掺量为1%,3%和5%试件的平均修复率分别为104.95%,118.28%和135.60%。EVA的掺入未明显降低标养水泥基材料基体的性能,且掺入适量的EVA能大幅提高试件的抗折强度。含EVA试件受热后抗压强度没有明显变化,而抗折强度和韧性因EVA-水泥浆界面的改善明显提高。当EVA掺量为5%时,受热后试件抗折强度和韧性分别提高了23.4%和130.2%。     

THE EFFECT OF TEMPERATURE ON CONTROLLED RELEASE OF HEPARIN FROM POLYURETHANE AND ETHYLENE VINYL ACETATE COPOLYMER

The objectives of this study were to examine the effect of elevated temperatures on the release kinetics of heparin from polyurethane (PU) and ethylene vinyl acetate copolymer (EVA), and on the biological activity of heparin released from the polymer matrix. Monolithic samples, prepared by dispersing heparin in solutions of PU and EVA, were fabricated and evaluated for in vitro release rates. Comparisons were made on the release rate of heated and non-heated samples. Heating at 120°C had little effect on the release kinetics from PU and an increase on release from EVA. Bioactivity of pure heparin and heparin released from PU was also evaluated and were found to remain stable up to 210°C.     

BENZYL ACETATE FROM PHASE TRANSFER CATALYZED ACETATE DISPLACEMENT OF BENZYL CHLORIDE

The overall production rate equation of benzyl acetate by L-L phase transfer catalyzed acetate displacement of benzyl chloride were derived. The experimental results of the effects of stirring speed, structure and amount of catalyst, reaction temperature, amount of sodium acetate, and phase volume-ratio on the production rate of benzyl acetate are elucidated with the rate equation. Benzyltributylammonium chloride is the recommended catalyst. The apparent activation energy of the displacement of benzyl chloride with the ion pairs of benzyltributylammonium acetate is 8.13kcal/mol. Sodium sulfate is a suitable salt to improve the partition coefficient of the phase transfer catalyst. The cocatalyst, sodium iodide, can greatly improve the production rate of benzyl acetate when its amount do not exceed 3 mol% of the substrate, benzyl chloride. Under the conditions of 5mol% benzyltributylammonium chloride, phase volume-ratio 0.429, stirring speed 520 rpm, reaction temperature 70°C, and 50% aqueous sodium acetate, about 80% yield of benzyl acetate can be obtained within 2 hrs. of reaction time.     

松节油一步法合成乙酸松油酯

论述了松节油与冰乙酸一步法合成乙酸松油酯工艺。     

MODELING OF DRUG RELEASE FROM A SWELLABLE MATRIX

In many polymeric controlled release systems (CRSs) the drug release kinetics is mainly ruled by the penetrant absorption characteristics which, in turn, depend on the viscoelastic properties of the polymer/penetrant system. The kinetics of the drug release process can follow either a typical Fickian behavior or a non-Fickian one (anomalous release), depending on the polymer/ penetrant viscoelastic properties. The aim of this work is to model such physical evidences by means of the appropriate flux equations describing the penetrant uptake and the corresponding drug release.

As a main result of our work we prove that, by resorting to the Sarti and Camera-Roda flux equation for the penetrant, and to the Fick flux equation for the drug, it is possible to simulate both Fickian and non-Fickian drug release from swelling CRSs characterized by different viscoelastic properties of the polymer/penetrant system. Furthermore, we demonstrate that the effect of the density gradient developing inside the matrix during the drug release does not sensibly affect the drug release kinetics.     

THE SEPARATION OF METHYL ACETATE FROM METHANOL BY EXTRACTIVE DISTILLATION

Methyl acetate cannot be completely removed from methyl acetate-methanol mixtures by distillation because of the presence of the minimum binary azeotrope. Methyl acetate can be readily removed as overhead product from mixtures containing it and methanol by using extractive distillation in which the extractive distillation agent is a higher boiling oxygenated, nitrogenous and/or sulfur containing organic compound or a mixture of these. Typical examples of effective agents are dimethylsulfoxide, glycerine plus propylene glycol, ethylene glycol plus dimethylsulfoxide plus 1,5-pentanediol. Methanol can be removed as the overhead product from methyl acetate when the extractive distillation agent is nitrobenzene, propylene carbonate or ethylene glycol phenyl ether.     

THE SEPARATION OF METHYL ACETATE FROM METHANOL BY EXTRACTIVE DISTILLATION

Methyl acetate cannot be completely removed from methyl acetate-methanol mixtures by distillation because of the presence of the minimum binary azeotrope. Methyl acetate can be readily removed as overhead product from mixtures containing it and methanol by using extractive distillation in which the extractive distillation agent is a higher boiling oxygenated, nitrogenous and/or sulfur containing organic compound or a mixture of these. Typical examples of effective agents are dimethylsulfoxide, glycerine plus propylene glycol, ethylene glycol plus dimethylsulfoxide plus 1,5-pentanediol. Methanol can be removed as the overhead product from methyl acetate when the extractive distillation agent is nitrobenzene, propylene carbonate or ethylene glycol phenyl ether.     

纳米介孔分子筛球作为难溶性药物长效缓释的研究

以难溶性的药物布洛芬为模型药物,以150nm的介孔分子筛球为载体,通过三甲基氯硅烷对介孔分子筛球不同程度的修饰,精细调节有机基团(CH3)3Si-在介孔表面的嫁接量实现药物的长效释放。总结了药物释放规律,同时用粉末X射线衍射(XRD)、红外光谱(FT-IR)、高分辨率透射电镜(TEM)和N2吸附-脱附对样品进行了表征。     

青梅醇提物中乙酸乙酯萃取组分的GC-MS分析

青梅醇提物中的抗氧化活性成分主要被乙酸乙酯所萃取.对青梅乙酸乙酯萃取组分进行了GC-MS分析,共检测出24个峰,其中鉴定出14种成分.主要成分为各类有机酸类化合物,约占总量的72.99%,其中含量较高的是柠康酸酐20.31%、6-十八碳烯酸16.58%、顺-油酸12.6%、十六烷酸10.72%、十八烷酸6.17%、癸酸1.97%、辛酸1.33%等.其次是二氢香豆酮7.38%和(2S)-1,3,4,5,6,7-六氢-1,1,5,5-四甲基-2H-2,4a-甲桥萘2.09%.     

ANALYSIS OF BURST RELEASE OF PROXYPHYLLINE FROM POLY(VINYL ALCOHOL) HYDROGELS

The initial high-rate drug release observed at the beginning of many controlled-release processes can be caused by a number of mechanisms, including surface desorption, pore diffusion, or the lack of a diffusion front barrier to regulate the diffusive process. This initial nonsteady-state period is usually referred to as "burst release." A small molecular size drug, proxyphylline, was used as a model solute to study the burst release of a drug from swellable hydrogels based on cross-linked poly(vinyl alcohol) (PVA). The influences of several factors, including drug loading concentration, initial cross-linking ratio of the polymer, initial swollen state of the hydrogel samples, pore diffusion of the drug versus swelling of the hydrogel at the beginning of the release, and osmotic pressure, were investigated to understand the burst behavior. Results show that high drug loading and low cross-linking ratio of the polymer led to more pronounced bursts. Compared to release experiments starting with relaxed samples, samples in dry states had magnified burst effects, but prolonged the release process. Pore diffusion of the drug at the initial stage and the osmotic pressure were shown not to be effective factors leading to burst release within the range of the experimental conditions of this study.     

煤热解和气化过程中硫分析出规律的研究进展

总结了当前煤中硫分的主要存在形态及其在煤转化（包括热解和气化等）过程中硫分变迁规律的研究进展,并探讨了煤阶和煤中硫的赋存形态,以及操作条件对煤中硫分析出规律的影响,这些形成了煤热解部分气化预脱硫工艺的理论基础,这对于指导燃前脱硫工艺的研究与开发是非常重要的。     

日用陶瓷铅溶出量与儿童多动症关系的探讨

根据目前日用陶瓷铅溶出量状况和铅中毒儿童多动症的研究结果，论证了日用陶瓷铅溶出量与儿童多动症存在相互关系，介绍了日用陶瓷铅溶出量与铅中毒检测方法，对铅中毒儿童多动症的预防和治疗提出了建议。     

APPLICATION OF A DISSOLUTION-DIFFUSION MODEL TO THE RELEASE OF 5-FLUOROURACIL FROM POLYMER MICROSPHERES

A theoretical discussion of drug release from microspheres is provided and a model-based predictive algorithm developed. The model verification step includes literature data describing the release profile of 5-fluorouracil (5-FU) from poly(lactic acid) polymer. Material balance equations were written to describe drug transport from a porous sphere. The model included combined effects of dissolution, diffusion, and void fraction on the release of 5-FU and was validated against in vitro experimental data. Analyses, conducted on published 5-FU release test data, revealed that the process was governed by a dissolution-diffusion mechanism. Approximately 1.5 million microspheres were formed; the drug density, diffusivity, and dissolution rate constant were estimated at 1.110 g/cm³, 2.324 × 10^?15 m²/s, and 17.60 g/m³h, respectively. The dissolution rate was faster than the rate of diffusion by a ratio of 12.79 to 1. Manipulation of the microsphere porosity was an effective way to influence the diffusion-controlled process. The procedure, outlined in the study, for estimating process properties will help fabricate microspheres that meet specific requirements.     

二醋酸亚乙酯裂解制醋酸乙烯系统中部分二元汽液平衡

用自吸循环高压平衡釜,测定了乙醛-二醋酸亚乙酯、醋酸-二醋酸亚乙酯、乙醛-醋酐、醋酸乙烯-二醋酸亚乙酯、醋酸乙烯-醋酐5组二元体系的恒温汽液平衡数据．对缔合体系的汽相采用“化学理论”修正其非理想性,采用UNIQUAC方程对液相的非理想性进行修正．计算结果令人满意．     

降低陶瓷装饰材料铅、镉溶出的对策与研究

对已有文献中关于降低陶瓷炊餐具铅、镉溶出量的对策进行了归纳，叙述了无铅、镉陶瓷炊餐具装饰材料用釉料、颜料的研究进展，并提出了今后陶瓷炊餐具装饰材料的发展方向。     

KINETIC STUDY ON THE EXTRACTION OF COPPER FROM AQUEOUS ACETATE BUFFERS WITH VERSATIC ACID 10

The extraction rate of copper(II)from aqueous acetate buffer solutions into Versatic Acid 10 dissolved in kerosene has been investigated using a constant interfacial-area unit cell. Two alternative kinetic equations were derived under the assumption of Langmuir adsorption isotherm for the organic phase - interface distribution of extractant. Experimental results show that the overall reaction is controlled by the formation step of the second intermediate complex,CuR HR, and that the forward extraction rate is proportional to the copper concentration in the aqueous phase, inversely proportional to the hydrogen ion concentration and proportional to a more complex function of the Versatic Acid 10 concentration.     

RELEASE RATES FOR PINE SAWFLY PHEROMONES FROM TWO TYPES OF DISPENSERS AND PHENOLOGY OF Neodiprion sertifer

Comparisons of release rates, duration in the field, and catch efficiency of polyethylene and cotton roll dispensers for the sex pheromones of sawflies (Hymenoptera: Diprionidae) were conducted. The release rates of the Neodiprion sertifer (Geoffr.) and Diprion pini (L.) sex pheromones, the acetates of pentadecanol and (2S,3S,7S)-3,7-dimethyl (2S,3R,7R)-3,7-dimethyl-2-tridecanol from polyethylene dispensers were measured at different temperatures in the laboratory. The release rates for the substances depended on both the temperature and initial load in the vials. The catch from cotton rolls baited with 100 g of the acetate or propionate of 3,7-dimethyl-2-pentadecanol was compared to the catch from regularly renewed cotton rolls baited with 10 g of the same acetate. The catch was higher for the 100-g cotton rolls for, at most, 45 days, and there was no significant difference in catch between the acetate and the propionate. The catch in traps baited with polyethylene or cotton roll dispensers loaded with the acetate of 3,7-dimethyl-2-pentadecanol was compared and showed that cotton roll traps mirrored the decreasing release of the substance rather than the actual flight activity. The length of the flight period of N. sertifer in Sweden, the Czech Republic, Italy, and Greece did not exceed 100 days in any of the countries. By adjusting the initial pheromone load of the polyethylene vials to the expected temperatures, it should be possible to get a constant and sufficiently high release rate during the entire flight period.     

环境因子对底泥释放COD、TN和TP的影响研究

通过室内静态模拟试验研究了环境因子溶解氧、温度、pH和扰动对底泥释放COD、TP、TN的影响.研究结果表明,不同溶解氧水平下,COD、TN、TP的释放量均随着溶解氧水平的降低而增加;不同温度条件下,随着温度的升高,TN、TP的释放量不断增加,但COD在20℃释放量最大,在5℃释放量最小;不同pH条件下,COD、TN、TP的释放量呈现"U"字形曲线,即中性条件下释放量最小,酸性和碱性条件下释放量都较大,碱性条件下的释放量略高于酸性条件;不同扰动状态下,COD、TN、TP的释放量均随着扰动程度的加强而增大.