Use of seed gums from Tamarindus indica and Cassia fistula as controlled-release agents

Most seed gums have been widely used in oral and topical pharmaceutical formulations, cosmetics, and food products because of their hydrophilic properties. Gums from Tamariudus indica and Cassia fistula seeds were chemically modified by carboxymethylation to improve their functionalities. The objective of the present study was to characterize and evaluate crude and carboxymethylated gums from T. indica and C. fistula seeds to achieve the controlled-release of diclofenac sodium(DS) in matrix tablet form. Both crude and carboxymethylated gums were characterized by Fourier transform infrared spectroscopy, Xray diffraction, and scanning electron microscopy. The results revealed that the gums were successfully modified by carboxymethylation and that the modified gums were amorphous in structure and had better flow properties. The carboxymethylated gums from both plant seeds did not exhibit cytotoxicity at concentrations lower than 0.5 mg/ml. All gum samples used as polymeric controlled-release agents were formulated into DS matrix tablets. Hardness and thickness tests were conducted as in-process tests. Drug content estimation and in vitro drug release studies were carried out to evaluate the matrix tablets. Increasing the concentration of gums increased compression time and hardness while it reduced the thickness. Furthermore, the results fitted well with the Korsmeyer–Peppas model. Moreover, the DS tablets were found to release the drug by super case II transport(relaxation). In summary, the carboxymethylated gum from T. indica and C. fistula seeds is an excellent, naturally sourced gum with high physicochemical and functional qualities, and can potentially be used in pharmaceutical applications as a disintegrant, diluent, and drug release-controlling agent.

Interactions between Superplasticizer and Release Agents at the Concrete/Formwork Interface

Improving the knowledge of rheological and tribological characteristics of fresh concrete is important to contribute to the progress of construction sites and the final quality of the work. The objective of this study is to identify the effect of a superplasticizer based on polycarboxylic ether on the tribological behavior of fresh concrete at the concrete/formwork and concrete/oil/formwork interfaces. Friction tests on fresh concrete were carried out using a plan/plan tribometer. In order to study the behavior of the superplasticizer close to the formwork, three concretes with 30% of paste and different dosage of superplasticizer were formulated. The results show that the increase of the dosage of superplasticizer reduces the friction stress. The properties of the superplasticizer generate a deflocculating action of concrete grains and lead to a stabilisation of the soap-oil micellae present in the vicinity of the formwork. Thus, the efficiency of superplasticizer depends on the quantity of fines, on the quantity of soap formed and so, on the release agent formulation.

Parasitoid wasps as effective biological control agents

Biological control(biocontrol) is a safe, sustainable approach that takes advantage of natural enemies such as predators, parasitic insects or pathogens to manage pests in agroecosystems. Parasitoid wasps, a very large evolutionary group of hymenopteran insects, are well-known biological control agents for arthropod pests in agricultural and forest ecosystems. Here, we summarize the recent progress on the application of parasitoid wasps in biocontrol in China for the last five years. These include species diversity of parasitoid wasps, identification of dominant parasitoid wasps associated with insect pests and biocontrol practices(three types of biological control, i.e., classical, augmentative and conservation biological control) in several Chinese agroecosystems. We then treat different mass-rearing and release technologies and the commercialization of several parasitoid wasp species. We also summarize other work that may have a potential use in biocontrol, including the effect of plant volatiles on parasitoids and recent advance in the molecular mechanisms underlying the host regulation by parasitoid wasps. Future research area and applied perspectives are also discussed, noting that advances in biocontrol technologies in Chinese agriculture informs research at the global level.

Methylprednisolone microsphere sustained-release membrane inhibits scar formation at the site of peripheral nerve lesion

Corticosteroids are widely used for the treatment of acute central nervous system injury. However, their bioactivity is limited by their short half-life. Sustained release of glucocorticoids can prolong their efficacy and inhibit scar formation at the site of nerve injury. In the present study, we wrapped the anastomotic ends of the rat sciatic nerve with a methylprednisolone sustained-release membrane. Compared with methylprednisone alone or methylprednisone microspheres, the methylprednisolone microsphere sustained-release membrane reduced tissue adhesion and inhibited scar tissue formation at the site of anastomosis. It also increased sciatic nerve function index and the thickness of the myelin sheath. Our findings show that the methylprednisolone microsphere sustained-release membrane effectively inhibits scar formation at the site of anastomosis of the peripheral nerve, thereby promoting nerve regeneration.

Carobomer Based Controlled Release Designs of Atorvastatin Calcium Tablets Evaluated Using Quality by Design (QbD) Approach

The study carried out here was focused on developing conventional monolithic controlled release matrix tablet of Atorvastatin calcium using carbomer as release controlling polymer. This system ensures the drug release at the alkaline pH region where the drug has got maximum solubility. Further the study was concentrated on comparing the impact of gelling agent polyvinyl pyrrolidone on drug release. Quality by design tools were considered during formulation development and the polymer concentrations were optimized adopting the statistical tool, design of experiments (DoE). The optimized formulation of present study exhibited desired controlled drug release characteristics in the alkaline pH conditions and at acidic environment the drug dissolution was minimal as intended.

Control Effect of Slow-release, Long-acting and Multi-functional New Pesticides on Sugarcane Borders and Woolly Aphids

In order to select the long-acting,low toxic,low-risk and multi-functional new pesticides for the control of sugarcane borders and woolly aphids and precise and efficient application technology,the control effect of 10% monosultap · thiamethoxam granular formulation and 1% Bt · clothianidin granular formulation on sugarcane borders and woolly aphids were studied.The results showed that 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR had good control effects on sugarcane borders and woolly aphids.They were ideal slow-release,long-acting,low toxic and multi-functional new pesticides used to control sugarcane borders and woolly aphids.They could be used alternately with other pesticides to delay the emergence and development of pest resistance to pesticides.The best dosage of the two pesticides in the field was 45 kg/hm^2.They could be mixed with fertilizer( 1200-1800 kg/hm^2),scattered in sugarcane ditches or at the base of sugarcane plants,and covered with soil or film from January to July.The control effect on dead heart seedlings damaged by borers could be up to above 79.2%,and the control effect on sugarcane woolly aphids could reach more than 98.8%.In comparison with the control group,the actual yield and sugar content of sugarcane increased by above 41 555 kg/hm^2 and 6.5% respectively.The application of slow-release,long-acting,strong systemic and multi-functional new agents with fertilizer around roots is convenient,precise and efficient,labor-saving,time-saving and environmentally friendly,and is worthy of being widely applied in sugarcane areas.

Controlled Release of Naproxen Sodium from Supermacroporous Cryogels

Cryogels are gel matrices that have interconnected macropores and are formed in freezing-thawing systems. These interconnected macropores give elasticity to cryogels. Transdermal controlled-release systems can be used to deliver drugs with short biological half-life and can maintain plasma levels of very potent drugs within a narrow therapeutic range for prolonged periods. In this study, cryogels have been used in a different area--transdermal controlled-release system, to obtain controlled drug release medium. For this purpose, naproxen sodium has been selected as a model drug. Naproxen, a propionic acid derivative, is a NSAID （nonsteroidal anti-inflammatory drug）. For controlled releasing of naproxen sodium, cryogels that have naproxen sodium in macropores have been prepared in sheet form for local application. Acrylamide based cryogel bands have been synthesized by flee radical cryogelation process. These cryogel bands have different pore size and includes naproxen sodium in their pores. This cryogel material has been characterized by swelling tests and SEM. Then, releasing ofnaproxen sodium from cryogels has been investigated at two different pH values, 7.4 and 5.5. According to experimental data, it has seen that these cryogel matrices that including naproxen sodium in macropores could be used in controlled drug releasing systems as bandages or other transdermal controlled releasing agents at room temperature

Study the effect of formulation variables in the development of timed-release press-coated tablets by Taguchi design

In this investigation, the effect of formulation variables on the release properties of timed- release press-coated tablets was studied using the Taguchi method of experimental design. Formulations were prepared based on Taguchi orthogonal array design with different types of hydrophilic polymers (X1), varying hydrophilic polymer/ethyl cellulose ratio (X2), and addition of magnesium stearate (X3) as independent variables. The design was quantitatively evalu-ated by best fit mathematical model. The results from the statistical analysis revealed that factor X1, X3 and interaction factors between X1X2 and X1X3 were found to be significant on the re-sponse lag time (Y1), where as only factor X1 was found to be significant on the response percent drug release at 8 hrs (Y2). A numerical optimization technique by desirability function was used to optimize the response variables, each having a different target. Based on the re-sults of optimization study, HPC was identified as the most suitable hydrophilic polymer and incorporation of hydrophobic agent magnesium stearate, could significantly improve the lag time of the timed-release press-coated tablet.

水工调蓄水池池壁混凝土预制板外观质量试验研究

为兼顾混凝土外观质量与耐久性,基于宁夏扁担沟扬水灌区吴家沟调蓄水池工程,研究了减水剂类型、引气剂类型和脱模剂类型对池壁混凝土预制板外观质量的影响。结果表明,掺入萘系减水剂的试件外观质量明显优于掺入聚羧酸减水剂的试件;掺入松香类、AOS和三萜皂甙引气剂的试件外观质量明显优于掺入醚类引气剂的试件;在保证混凝土力学性能和耐久性的前提下,适当增大水胶比,减小混凝土黏度,有利于气泡的排出;喷涂水性脱模剂浓度为0.05%~0.10%时,试件表面平整光洁,几乎无气泡,工程应用效果良好。

基于Agent的同类机智能调度算法

研究了目标函数是最小化最大完成时间的同类机调度问题,且作业到达时间可能不同。此问题被证明是NP-hard问题。为此问题构建了一个基于Agent的智能调度算法ABH,使得机器具有一定的智能性,从而实现工厂调度的自动化。给出了用于调度的两类Agent的语义描述,进而给出ABH算法描述。大量随机数据实验结果表明,ABH算法性能明显优越于现有算法,其相对于最优解的平均误差收敛达0.084%。

清水混凝土的表面气孔缺陷形成与调控研究进展

清水混凝土因直接采用现浇混凝土的自然质朴外观作为饰面,可实现建筑美学表达与低碳节能的完美融合,在工程中得到广泛应用。混凝土表面气孔缺陷调控是制备清水混凝土的关键难题,究其根源,在于影响混凝土表面气孔的因素众多,且各因素间耦合作用,但气孔形成的本质尚不明晰。近年来,人们从混凝土材料与施工工艺等角度,尝试提出关于混凝土表面气孔的定量影响规律,以望指导清水混凝土的制备及施工。本文总结了混凝土表面气孔的形成与调控的研究进展(从气泡转变为表面气孔的全过程),梳理了其中的关键作用机制(气泡形成-粗化-迁移-黏附),介绍了混凝土表面气孔缺陷评价、拌合物气泡结构演化、振动时流变状态对气泡逃逸的作用以及模板/脱模剂对气孔形成的影响这四个方面的内容,总结了主要的结论与存在的问题,最后对混凝土表面气孔形成机理与调控方法的发展及应用进行了展望。

一种Java Agent角色动态加载与释放的实现方法

角色的加载与释放是基于Agent社会组织系统仿真中的重要方面。本文结合HJcass复杂系统仿真平台的设计,在代码级别上实现了Java Agent角色的动态加载与释放。首先分析了基于AGR的社会组织仿真中角色加载与释放的具体需求,指出了RoleX系统在组织系统仿真应用中的局限性;然后结合这些具体需求,给出了角色动态加载与释放算法;并根据这些算法,针对RoleX系统的局限给出了一种基于BCEL的实现方法。

镇江苏南储备粮浅圆仓滑模施工技术研究

针对镇江丹阳市苏南储备粮项目10个浅圆仓滑模施工技术进行研究。项目采用54个提升支架、54个6 t千斤顶的滑模系统,研究表明水灰质量比0.43、重量2300 kg/m^(3)的混凝土配合比能确保出模强度控制在0.2 MPa~0.4 MPa。通过优化施工工序,实现两个专业班组28 d完成10个浅圆仓滑模施工。采用300 mm分层浇筑、2 h滑升间隔的施工工艺,有效保证了混凝土质量。结合实际工程验证,该技术方案可确保浅圆仓滑模施工的平整度、垂直度等各项技术指标满足设计要求。

有机硅锚固剂的合成及在有机硅离型剂中的应用

目的:提高有机硅离型剂在聚乙烯(PE)基材上的锚固性。方法:以含氢硅油和烯丙基缩水甘油醚(AGE)在铂催化下进行硅氢加成反应,合成一种特殊结构的有机硅锚固剂(SEA)。结果:添加0.5 wt%的SEA到无溶剂加成型有机硅离型剂中,在70℃和90%相对湿度(RH)的条件下老化4 d,可以达到离型涂层无搓落的较好锚固性,并且具有较优的剥离力和残余接着率。结论:所制备的SEA对提升离型剂在PE基材上的附着性有较好的效果。

RESEARCH ON OXYGEN-RE LEASING AGENT FOR PRAWN CULTURE

A solid powder oxygen-releasing agent was developed and tested in prawn culture. Dissolved oxygen (DO) is a basic necessity for aquatic life and is affected by water temperature, climate, plankton, etc. DO variation in culture ponds strongly and consequently affects prawn growth and production output.In summer, when air temperature is high, pond water is polluted (by prawn feed leftovers) and cannot be changed fully and as frequently as necessary; especially at night, when there is no sunlight for photosynthesis with oxygen as a by-product, the DO in pond water can decrease rapidly. Under the above circumstances, the prawns experience serious lack of oxygen before dawn and die in large number. To solve this problem, we developed an oxygen-releasing agent with excellent perform -ance.

NUMERICAL SOLUHON TO THE PROBLEM ON DlFFUSION OF CATALYTIC AGENTS RELEASED FROM AN AIRPLANE

A solution to the problem on diffusion of catalytic agents released from an airplane is sought.The variation of falling velocities of agent particles with the altitudes is taken into account in the study of the problem.A comparison is also made between the calculated results obtained by using the finite-difference method and those by using the analytic method,the similarities and the differences between the two methods are revealed.

苏里格气田低渗储层解水锁剂的制备及性能评价

针对苏里格气田低渗储层岩石表面特性及水锁成因,通过对润湿反转剂、酸液及缓蚀剂等药剂进行筛选优化,确定出最优的解水锁剂配方;并在此最优解水锁剂配方下,进行了解水锁剂性能评价、岩心自吸实验及苏里格气田5口低产井解水锁实验。实验结果表明,最优的解水锁配方为0.5%(w)乙烯基三甲氧基硅烷+0.01%(w)非离子表面活性剂+10%(w)CH_(3)CH_(2)OH+1.5%(w)缓蚀剂+0.5%(w)HCl+1.0%(w)CH_(3)COOH+3.0%(w)HF;解水锁剂可将亲水性岩石表面反转为强气润湿性,接触角从58.73°增加到130.81°;解水锁剂处理后的岩心自吸水量降低74.8%,岩心气测渗透率回复率达到80.6%~88.7%;施工后的气井产能显著提高,日增气量达到(0.54~3.09)×10^(4)m^(3),起到了很好的解水锁效果。

水泥基材料无机/有机复合内养护剂的研究进展

无机/有机复合吸水材料具有一定的亲水基团和三维网络结构,吸水性、保水性和释水性优异,是水泥基材料重要的内养护剂之一。通过在水泥基材料中引入无机/有机复合吸水材料,利用其吸-释水特性可自动调节水泥基材料内部相对湿度,促进水化反应,减少水泥基材料自收缩和早期开裂等现象,提高力学性能和耐久性。概述了无机/有机复合内养护剂(CICA)的制备方法、结构特征以及吸-释水行为;综述了CICA对水泥基材料水化进程、微观结构、宏观性能和耐久性的影响;展望了CICA在混凝土应用的发展前景,为CICA在水泥基内养护中的应用提供一定理论指导和技术参考。

一种O/W型聚氨酯水性外脱模剂的制备及性能研究

传统油基脱模剂含有可能对环境产生污染的有机溶剂,随着全球环保意识的增强,更为绿色环保无毒的水性脱模剂逐渐成为研究热点.为了开发汽车内饰使用的新型脱模剂,以二甲基硅油、含氢硅油等为主要原料,制备出一种O/W型聚氨酯水性外脱模剂.通过测定脱模剂样品性能,探讨了主脱模剂种类及配比、乳化体系复配比例对脱模剂性能的影响.采用能谱仪(EDS)对脱模后的聚氨酯泡沫表面进行元素分析.结果表明:二甲基硅油和含氢硅油按照1∶1配比作为基础聚合物,固含量19.41%,采用非离子表面活性剂SP⁃80、TW⁃80复合乳化体系制备的O/W型聚氨酯水性外脱模剂稳定性最好,脱模后的聚氨酯泡沫表面没有Si元素残留,具有最佳脱模效果.

γ射线辐照合成草甘膦异丙胺盐缓释剂及其性能

为提高农药利用率,减少农药使用量,有效解决农药对环境造成的不良影响,本研究采用辐照处理一步法对淀粉改性制得一种载体材料,通过负载草甘膦异丙胺盐后得到草甘膦异丙胺盐缓释剂。利用扫描电镜、红外光谱对缓释剂的形貌特征及结构组成进行表征,并探究了不同载药体系的缓释性能、表面张力及除草活性。相比于未负载的和凹凸棒土负载的草甘膦异丙胺盐,在720min时缓释剂的释放速率分别减缓了44.00%和20.45%;凹凸棒土负载的草甘膦异丙胺盐释放达平衡时间为1440min,而缓释剂为1700min。通过动力学分析拟合,草甘膦异丙胺盐释放曲线的First-order模型的相关系数R2在0.9566~0.9972,拟合度较高。进一步对比除草活性发现,草甘膦异丙胺盐缓释剂对稗草具有更优异的防治效果。综上所述,通过辐照制备载体材料的方法简单高效、节能环保,在此基础上合成的草甘膦异丙胺盐缓释剂具有良好的缓释性能及除草活性,为开发农药缓释剂提供了一种新方法。