Sustained Release Matrix of Mebeverine Hydrochloride Using Polyacrylate Resin “Eudragit Retard” Kinetic of Drug Release and Evaluation of a Kinetic Model

Abstract

In this study Eudragit RS PM and RL PM were evaluated as carriers for the preparation of prolonged release solid dispersions of mebeverine hydrochloride by solvent and melting methods. The prepared tablets were examined for dissolution at pH 1.2 and 7.4, Eudragit RS PM and RL PM were found satisfactory as potential slow release carriers. The solid dispersion prepared by the solvent method showed a slow release pattern. Drug release appeared to fit both, first order and Higuchi matrix model kinetics. However, on application of the differential rate treatments, the evidence supported the Higuchi matrix model. Effect of temperatures on dissolution rate was studied for thermodynamic consideration.

The drug release was pH-independent until pH 7.4.As the pH increased, the release was significantly reduced due to solubility problem.     

“Reservoir Model” for Shallow Modulation-Doped Digital Magnetic Quantum Wells

Digital magnetic heterostructures (DMH) are semiconductor structures with magnetic monolayers. Here we study electronic and magnetotransport properties of shallow modulation-doped (ZnSe/ZnCdSe) DMHs with spin-5/2 Mn impurities. We compare the reservoir model, possibly relevant to shallow geometries, to the usual constant-density model. Our results are obtained by solving the Kohn-Sham equations within the local spin density approximation (LSDA). In the presence of a magnetic field, we show that both models exhibit characteristic behaviors for the electronic structure, two-dimensional carrier density, Fermi level and transport properties. Our results illustrate the relevance of exchange and correlation effects in the study of shallow heterostructures of the group II-VI.     

“Assessment of Metal Matrix Composites for Innovations” — intermediate report of a European Thematic Network

The Thematic Network “Assessment of Metal Matrix Composites for Innovations” (acronym MMC-ASSESS) is a consortium of 21 partners from industry, research organisations and universities involved in research, development and application of metal matrix composites (MMC). The general goal of the project is to increase market acceptance of MMC by collecting and evaluating information related to the engineering potential of these materials. The working groups of the network are referring to production, characterisation and properties as well as modelling and applications of MMC. These topics are considered as well specifically for the four categories of MMC: particulate, short fibre and whisker, continuous fibre, and monofilament reinforced metals. A web page has been established (http://mmc-assess.tuwien.ac.at/) as an ongoing dissemination activity. An intermediate report on the network's activities is presented, which started in October 1998 by funding of the European Commission for a 36 months period.     

A Generic and Effective Strategy for Highly Effective “Intrinsic”Molecular Luminescence in Condensed State

正Organic light-emitting(OLE)materialshave been extensively studied due to their easy mod-ification,However,the easy crystallization to re-sult in instable spectral performance and quenchingeffect of luminescence,poor processability and lowthermal stability have limited their applications.Polyhedral oligomeric silsesquoixanes(POSS)are a class of inorganic compounds with nanoscale     

Simplicitas就是“简单”!

“面对错综复杂和易变的世界，我们寻找明显而大众所没有考虑到的解决日常生活问题的简便方法。完美在于细节．我们相信我们的设计者具有引导性的设计技能和高度的创新意识。再普通的产品只要它还在材料、外型、重量、色彩、手感甚至是心理直觉上有任何一点点的问题．它就不算被设计完成。这就是我们所一直秉承的理念“     

“张弓”不可伤人!

6月8日,笔者应邀出席午宴,席间上了“张弓酒”。小姐打开酒瓶为每人斟满一杯后,有别的事离开。“干杯”之后,笔者取过酒瓶为在座各位斟酒。有谁知,当我右手拿过酒瓶、左手去取瓶盖时,大拇指内侧即被残留在瓶盖上的一块碎玻璃暗伤,一阵刺心痛后,便是一股血往外冒。用了好几张餐巾纸,也止不住流血。满桌人受惊,吃饭也不安耽。血流下来,搞得我衬衣、裤腿上都是。小姐设法弄来几张创口帖,但过不多久,血又溢出来了。最后,饭也未吃好,到医务室包扎、用药后才把血止住。但一时无     

Mode-Locked Lasers with “Thin” Quantum Wells in 1.55 μm Spectral Range

Technical Physics Letters - We present the results of an experimental study of two-section semiconductor lasers with active region consisting of three 3.1 nm InGaAs/InGaAlAs quantum wells. Passive...     

当心!欧元“假钞”泛滥

就在各国为了救市，刺激经济忙的不可开交的时候，假币也不甘示弱，抢尽了“风头”，高仿真人民币引起了国内的轩然大波，印度的假币数目骇人听闻，就连一向被认为“防伪性”较强的欧元，也成为造假者的新宠。     

“小喇叭开始广播啦!”

编者按：宋效曾是原中央乐团（现中国交响乐团）国家一级舞美、音响设计。曾任职于中央音乐学院音乐工作团。1982年主持北京音乐厅的设计与施工。曾任文化部科技委员。现任国家大剧院专家组成员。宋老师是资深的音响技术专家，对音响方面各种问题的见解十分深刻，此文选登于ffi－Fi音响栏目，意在开拓发烧友的眼界，对一些问题会有更科学的了解，譬如音量过大也是一种失真，这对于大音量听音乐的朋友会有一些启示，多听听专家的意见，可以使我们少走许多弯路。——编者这不是广播电台儿童节目的开始曲，而是说，小型扬声器的时代已经来到了…     

Religious commitment and its interaction with scientific professions: a low-church real-science,critique of “science” and “spirituality”

After a brief autobiographical background, as an activist scientist and engineer, the author offers a broad critique of the attempt to relate science and religion at the theoretical level. The important level at which to seek a relation, both scientifically and religiously, is one of practice, not theory. Indeed, because science as theory is itself in the process of reaching its own internal limits, because of the manifest failures of reductionist science and technology, it is time for scientists and engineers to return to Einstein's commitment to pursue science for the common good. The rising popularity of alternative medicine is also cited as a contemporary historical phenomenon that points toward an emerging, fundamental realignment of the science–technology–society relationship.     

Fabrication of Janus particles via a “photografting-from” method and gold photoreduction

Faster and simpler methods for the fabrication of Janus particles are of tremendous importance for a real implementation of these particles. By combining thiol-modified silica particles (SMPs) with the use of UV light, it is possible to rapidly fabricate Janus particles coated with polymer brushes and gold nanoparticles via photochemical emulsion-assisted route. From the silica particle surface, polymeric brushes of polyethylene(glycol), PEG, were grafted via a photografting-from method on one hemisphere by using the thiol groups as photoinitiator of the polymerization. The other hemisphere was coated with gold nanoparticles (AuNPs) generated in situ via photoreduction of chloroauric acid promoted by Norrish type I photoinitiator. PEG/AuNPs@SMPs coated with Au nanoparticles with average diameter of 12.7 or 22.5 nm were obtained by playing on the mass ratio between thiol-modified silica particles and gold precursor. The Janus PEG/AuNPs@SMPs were fully characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and UV–Vis spectroscopy. This strategy merges the advantages of emulsion-based selective masking and UV-induced reactions, and it is proved to be a feasible and fast route (reactions are completed in dozens of minutes) for Janus particles fabrication.     

Measuring “publications output” and “publications impact” of faculty members of a university chemistry department

The publication and citation records of a group of 34 senior members of the faculty of the Department of Chemistry at Technion-Israel Institute of Technology over the period 1980–90 have been analyzed under the contention that dealing with a small group makes it possible for one to pay adequate attention to the methodology of the measurement and analysis processes. Choosing the most suitable index for measuring Publications Output has been considered in detail; it is suggested that it is essential to make allowances for both the number of co-authors and for the lengths of publications in order to obtain a more valid measure than is provided by a simple count of equally-weighted publications. Analogously it is argued that simple citation counts provide an inadequate measure of the impact that publications make on the group outside the authors' immediate circle and thus that it is necessary to subtract self citations and divide the credit for a citation among the co-authors of the publication. Results of the analysis show that in agreement with all previous findings a few members (perhaps less than 20%) produce more than half the publications and receive more than half the citations of the Group as a whole.     

Point-and-shoot Strategy based on Enzyme-assisted DNA “Paper-Cutting” to Construct Arbitrary Planar DNA Nanostructures

DNA self-assembly provides a “bottom-up” route to fabricating complex shapes on the nanometer scale. However, each structure needs to be designed separately and carried out by professionally trained technicians, which seriously restricts its development and application. Herein, a point-and-shoot strategy based on enzyme-assisted DNA “paper-cutting” to construct planar DNA nanostructures using the same DNA origami as the template is reported. Precisely modeling the shapes with high precision in the strategy based on each staple strand of the desired shape structure hybridizes with its nearest neighbor fragments from the long scaffold strand. As a result, some planar DNA nanostructures by one-pot annealing the long scaffold strand and selected staple strands is constructed. The point-and-shoot strategy of avoiding DNA origami staple strands’ re-designing based on different shapes breaks through the shape complexity limitation of the planar DNA nanostructures and enhances the simplicity of design and operation. Overall, the strategy's simple operability and great generality enable it to act as a candidate tool for manufacturing DNA nanostructures.     

A Study of the “Needle” and “Bell” Discharge Burning Modes in a 1.5-kW Hall Thruster

Technical Physics Letters - Two discharge burning modes (“needle” and “bell”) have been experimentally studied for a Hall thruster with a nominal power of 1.5 kW. The...     

Development and Verification of a Scheme for Fractionation of HAWs with TODGA Extractive Agent in a “Light” Diluent

Radiochemistry - The technology of fractionation of trans-plutonium elements (TPEs) and REEs with the use of 0.15 M TODGA (tetraoctylamide of diglycolic acid) + 5% n-decanol in Isopar-M as...     

请手下留情!──古建筑“整容”师

美是多元化的，不能千篇一律。假设一个美容师具有高超技术能给一位七老八十的老妇整容，使她变成一个二十几岁的姑娘形象，即使真能如此，老妇将失去了自己应有的位置。此类过头的“整容”同样也出现在某些古迹遗址的修复工程之中。当今，我国政府正下大力气拨款鼓励有关方面执行修复，要把名胜古迹包装得自然得体。然而具体操作人员的审美水准使他们过于简单化，严重忽视了古建筑修复应力求还原的原则和艺术精神。上海老城皇庙的修复工作就是一例。目前它的新形象使不了解其典古风貌的人以为它历来就是今天这个模样，而深知其历史形象的人…     

烧“包”乐趣!——摄影包导购

谁发明了世界上第一款摄影包?可能很多人会说,有第一台照相机的时候就有了吧,这你可就错了!世界上第一台照相机需要马车拉的,当然不可能有什么相机包可以装下它。后来随着相机的体积越做越小,烧包一族从此也诞生了!