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991.
992.
Sachin Patil Sameer Sharma Anagha Nimbalkar Atmaram Pawar 《Drug development and industrial pharmacy》2013,39(3):315-326
ABSTRACTThe aim of the present study was to obtain cross-linked calcium-gellan beads containing diclofenac sodium as model drug, using full 33 factorial design. Drug quantity, pH of cross-linking solution, and speed of agitation were selected as variables for factorial design. The resultant beads were evaluated by scanning electron microscopy (SEM), percent yield, entrapment efficiency, micromeritic properties, swelling and drug release studies. The drug-loaded beads were spherical with size range of 0.85–1.8 mm. Percent yield and entrapment efficiency of various batches were in the range of 86.48–98.28% w/w and 72.52–92.74% w/w, respectively. Calcium-gellan beads containing diclofenac sodium showed pH-dependent swelling and drug release properties. Swelling and drug release were significantly higher in pH 7.4 phosphate buffer than 0.1N HCl. The swelling ratio for beads was up to 22 and 3 for phosphate buffer and 0.1N HCl, respectively. Cumulative diclofenac sodium release from calcium-gellan beads was 12–35% in 0.1N HCl within 2 h, whereas complete drug release was observed within 3–4 h in pH 7.4 phosphate buffer. 相似文献
993.
Abstract: The precipitation characteristics and effect on strengthening mechanism of Cu-rich phases during short-time and long-time aging in the Super 304H steels with different Cu contents were investigated by the use of X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results show that the size of Cu-rich phase particles increases, the distance of Cu-rich phase particles decreases and the density of Cu-rich phases increases with the increase of Cu content during short-time aging (~ 800 h) at 650℃ in the Super 304H steels. During long-time aging (>2000 h) at 650℃, Cu-rich phases precipitate sufficiently and the strengthening effect of Cu-rich phases is preferable in the Super 304H steel with 4% Cu. The strengthening effect of Cu-rich phases in the Super 304H steels with 2.2 % Cu or 5 % Cu is weaker than that with 4% Cu during long-time aging (>2000 h). 相似文献
994.
995.
TD-LTE无线网络规划若干问题探讨 总被引:1,自引:1,他引:0
本文对TD-LTE无线网络规划中所涉及的几个关键问题进行了分析和讨论,主要包括频率使用策略、多天线方案选择、调度算法的应用以及基站传输带宽需求等4个主要问题。文章中对4个主要问题进行了分析和研究,并给出了现阶段条件下的应用策略或建议。 相似文献
996.
Basics of analytical methods used for the investigation of interaction mechanism between cements and superplasticizers 总被引:2,自引:0,他引:2
Kazuo Yamada 《Cement and Concrete Research》2011,(7):793-798
In order to better understand the interactions between cements and superplasticizers (high-range water reducers), various analytical methods have traditionally been applied, but some of these methods can introduce significant errors. In this paper the fundamental interaction mechanisms are reviewed and appropriate methods and sample preparation conditions are explained in detail. For superplasticizer adsorption measurements, analysis by size exclusion chromatography is useful in order to avoid the effect of other organic compounds released from cement by the action of the superplasticizer. For BET specific surface area measurements it is important to avoid pre-drying at over 60 °C, as otherwise ettringite can decompose and strongly increase the surface area. In order to evaluate pore solution chemistry correctly the aqueous phase must be extracted without dilution. In addition, the fluidity performance of many cements in superplasticized concretes can be changed simply by passage through a storage silo, for reasons which are not yet understood. 相似文献
997.
主要介绍美国ABBEL3040一Magnos206在线磁氧分析仪在壳牌煤气化装置中的应用。通过对被测样气工艺,氧分析仪的测量原理,样品采样、预处理系统等的介绍,加以实例分析说明,叙述了该表在使用过程中遇到的问题、解决方法及技术改造等。 相似文献
998.
客车和轻卡在同一电泳线上生产,必须解决客车沥水干净、不同车型混线生产槽液参数不易控制等难题。通过在轻卡电泳线上增加客车电泳的生产实践,研究出了解决客车和轻卡车混线电泳生产难题的方法。 相似文献
999.
For the diffusion-controlled adsorption, the expression of dynamic surface adsorption Γ(t) was ob-tained by solving the diffusion equation. Two cases, i.e. the short and long time limits, were mainly d... 相似文献
1000.
为研究一类采用斜直螺栓、不设传力衬垫构造形式的盾构管片接头在高荷载水平下的破坏力学性态,在引入一定假设基础上,提出了可用于分析管片接头破坏历程的简化解析模型,并对简化模型在线性转动、接头张开、接头屈服等不同阶段的接头截面应力分布和转动情况进行了分析和推导。并通过弯矩-转角关系曲线和接头极限弯矩两个方面对本文简化力学模型的解析解与管片接头足尺试验结果进行了比较和验证,比较结果表明,该方法所得结果与试验结果基本一致,是可行的。 相似文献