粉煤灰对砂浆流变性和强度的影响研究

本文通过正交试验研究水胶比、砂胶比和粉煤灰掺量对砂浆流变性和抗压强度的影响。实验结果表明:水胶比和砂胶比是影响砂浆流动性的主要因素;通过正交试验得出水胶比为0.55、砂胶比为2.65、粉煤灰掺量为25%,流动性和保水性均符合砂浆使用要求,砂浆抗压强度明显高于其他组砂浆抗压强度。     

基于冲填砂浆结石技术的混合砂浆性能正交性试验研究

为了研究水胶比、粉煤灰掺量和沙漠砂取代率对冲填砂浆结石技术的混合砂浆性能的影响,采用粉煤灰部分取代胶凝材料,沙漠砂代替中砂,拌制砂浆,并进行正交性试验.通过层次分析和综合平衡分析得到各因素、各水平的影响权重和最佳配比方案.结果表明:沙漠砂取代率和粉煤灰掺量是影响砂浆稠度的主要因素,粉煤灰掺量是影响分层度和28 d抗压强度的主要因素,而影响90 d抗压强度主要因素的是水胶比.对于一般工程项目,由各因素、各水平的权重之和得到的最优试验组合为:水胶比为0.975,粉煤灰掺量为20％,沙漠砂取代率为20％.最优配比均能满足砂浆强度M10砂浆的配制要求,且经济合理.     

缓凝砂浆流动性和力学性能试验研究

为研究水胶比、砂胶比和硅微粉掺量对缓凝砂浆流动性和力学性能的影响,分别测试了水胶比为0.30、0.40、0.45、0.50,砂胶比为0.5、1.0、1.5、2.0、2.5和硅微粉掺量为0.0％、5.0％、10.0％共22组缓凝砂浆的稠度、立方体抗压强度、轴心抗压强度、劈裂抗拉强度和静弹性模量.研究结果表明:随着水胶比的增大,缓凝砂浆流动性增大;随着砂胶比增大,缓凝砂浆流动性较小;硅微粉掺量增加会降低缓凝砂浆流动性.采用灰色关联理论分析水胶比、砂胶比和硅微粉掺量对硬化后缓凝砂浆的力学性能影响规律,得到水胶比为影响硬化后缓凝砂浆力学性能的关键因子,而砂胶比次之,硅微粉掺量影响相对最小.     

高韧性水泥基复合材料抗压强度正交试验研究

利用正交试验设计原理,对9组不同配合比的高韧性水泥基复合材料进行了抗压试验,研究了粉煤灰掺量、水胶比、砂胶比和减水剂掺量这四种因素对高韧性水泥基复合材料抗压强度的影响,并定量分析了各个因素影响的显著性.试验结果表明:各因素对抗压强度影响的主次顺序为水胶比＞粉煤灰掺量＞减水剂掺量＞砂胶比,其中水胶比对强度的影响远大于其他因素,而砂胶比的影响并不明显;抗压强度随水胶比的增大而减小,随砂胶比的增大而缓慢增加;当粉煤灰掺量或减水剂掺量增大时,抗压强度先增大后减小,粉煤灰和减水剂存在最佳掺量.     

磷石膏煅烧改性制备自流平砂浆的研究

采用磷石膏煅烧改性成的无水磷石膏(AP)、α型高强石膏(α-HH)、石英砂、外加剂等为原料制备磷石膏基自流平砂浆,分析探讨了煅烧温度、α型高强石膏掺量、胶砂比以及外加剂掺量对样品凝结时间、力学强度等性能指标的影响.结果 表明:磷石膏经500℃煅烧后,28 d抗压强度为13.6 MPa;增大α型高强石膏掺量有利于提高无水磷石膏力学强度;减小胶砂比能改善砂浆流动性能.采用42％无水磷石膏、28％α型高强石膏、30％石英砂、0.01％ PE、0.2％ MSF及0.1％ HPMC配制的磷石膏基自流平砂浆,其性能指标满足JC/T 1023-2007《石膏基自流平砂浆》的要求.     

脱硫石膏基无砂自流平砂浆的制备与性能研究

采用脱硫建筑石膏、P·O 42.5水泥、粉煤灰、石灰石超细粉以及外加剂为原料制备脱硫石膏基无砂自流平砂浆。采用正交试验确定石膏基胶凝材料的最优配合比,研究缓凝剂和纤维素醚对石膏基无砂自流平砂浆的性能影响,并利用XRD和SEM分别分析胶凝体系的水化产物和微观形貌,通过分析结果进一步研究外加剂的作用机理。结果表明:当脱硫石膏、水泥、粉煤灰和石灰石超细粉的质量比为16:1:2:1时,石膏基胶凝材料的强度最优;缓凝剂明显延长砂浆的凝结时间,但会导致砂浆产生泌水现象;纤维素醚可以提高砂浆的保水性,纤维素醚的引气作用造成砂浆强度下降。脱硫石膏基无砂自流平砂浆的性能指标满足《石膏基自流平砂浆》(JC/T 1023—2007)的要求。     

纤维石膏基复合墙材基本力学性能试验研究

以原状脱硫石膏、粉煤灰、矿渣作为基本材料,运用正交试验研究了由NaOH、生石灰和水泥组成的复合碱性激发剂对于原状脱硫石膏-粉煤灰-矿渣复合胶凝材料基本力学性能的影响,确定了NaOH、生石灰、水泥的最佳掺量.在此基础上,研究了不同植物纤维、水胶比、减水剂对复合胶凝材料基本力学性能的影响,确定了纤维石膏基复合墙材的最佳配比.试验结果表明:NaOH、生石灰、水泥的最佳掺量分别为0.5％,8％,10％,该复合墙材选用苎麻纤维和萘系减水剂为宜,最佳掺量分别为2％和1％,最佳水胶比为0.38,所有组分均在脱硫石膏、粉煤灰和矿渣质量和的基础上按质量比外掺.     

磷建筑石膏基无砂自流平砂浆的制备与性能研究

采用磷建筑石膏、P·O 42.5水泥、粉煤灰、矿粉、石粉及外加剂为原材料制备高强耐水型磷建筑石膏基无砂自流平砂浆。通过正交试验确定砂浆中胶凝材料的最优掺量,研究减水剂和可再分散性乳胶粉对砂浆性能的影响,并采用XRD及SEM对砂浆进行微观分析。结果表明,当磷建筑石膏、水泥、粉煤灰、矿粉及石粉质量比为73∶5∶5∶15∶2时,砂浆综合性能最优,28 d绝干抗压强度为33.0 MPa,软化系数为0.774。减水剂能够提高砂浆30 min的流动度、力学性能及耐水性能,但当掺量为0.30%(质量分数)时,会降低砂浆的后期强度。可再分散性乳胶粉会降低砂浆的流动性能及力学性能,但能提升砂浆的耐水性能。制备的磷建筑石膏基无砂自流平砂浆的性能满足《石膏基自流平砂浆》(JC/T 1023—2021)的要求,砂浆的28 d绝干抗折强度、28 d绝干抗压强度分别为12.0、45.9 MPa,软化系数高达0.886,吸水率低至2.8%。     

脱硫建筑石膏粉制备自流平砂浆的技术研究

本文主要研究了脱硫建筑石膏制备自流平砂浆.确定了基础配比:脱硫石膏1200 g,砂800 g,水1000 g,消泡剂0.5‰,纤维素醚0.3‰,乳胶粉8‰,缓凝剂2‰.研究了激发剂对石膏基自流平砂浆的性能影响,确定了激发剂掺量为3％.研究了高效减水剂对石膏基自流平砂浆的适应性,结果表明:不同的高效减水剂对砂浆强度有一定的提高作用,但对石膏基自流平砂浆有不同程度的不适应.研究了不同的灰砂比对砂浆性能的影响,确定了砂浆强度随灰砂比的变化趋势.XRD和SEM分析显示水化产物为长条状二水石膏,晶型完整.     

基于正交理论的玄武岩纤维活性粉末混凝土配合比设计

通过正交试验进行活性粉末混凝土(Reactive Powder Concrete,RPC)的配合比设计,选取水胶比、砂胶比、水泥/粉煤灰、减水剂、玄武岩纤维掺量为因素,设定相应的水平.运用极差法分析了上述因素和相应水平对RPC拌合物工作性及其力学性能的影响.结果表明,在标准养护条件下,当水胶比为0.2、粉煤灰取代水泥量为30％、减水剂为胶凝材料的2％、玄武岩纤维掺量为5 kg/m3时,可以配制出28 d抗压强度、抗折强度分别超过95.1 MPa、13.4 MPa的高强度活性粉末混凝土.     

Polysaccharide Based Nanoparticles

Nanoparticles made of biodegradable polymers have outstanding merits as a drug delivery system. Polysaccharide-based nanoparticles have been well explored because of their safety, stability, biocompatibility, biodegradability and hydrophilicity. The present review emphasizes the efforts articulated to improve polysaccharide-based nanoparticles as drug delivery tool for effective therapy and site-specific targeting of mainly anticancer agents. This review updates reports of recent research on polysaccharides-based systems particularly chitosan, alginate, cyclodextrins, hyaluronic acid, pullulan, dextran and their combinations with potential applications.     

碳质耐火材料

由于具有独特的性能，例如热导率高、热膨胀低、抗热震性能好、与渣接触化学活性小，因而碳质或含碳耐火材料被广为关注。它们被分为两类：碳砖/大块和含碳材料。含碳材料又被进一步划分为碱性含碳耐火材料和非碱性含碳耐火材料。分析了制造过程。对其物理性能、热性能、机械性能、化学性能也进行了评价。对这些类型耐火材料的抗氧化剂和结合剂也进行了评论。其应用也被仔细分析。     

Metallo-Phthalocyanines Based Photocapacitors

Silicon - The novel metallo-phthalocyanines (4–6) were obtained from the reactions of gereniol substituted phthalonitrile compound (3) with corresponding metal salts (Co (II), Cu (II) and Zn...     

基于GIS环境风险源基础数据管理研究

课题以Visual Studio 2012(VS 2012)为开发工具,结合地理信息空间数据库,SQL Server属性数据库,建立环境风险源基础数据管理系统。     

明胶基表面活性剂

<正> 表面活性剂是一类能够使体系表面状态发生明显变化的物质,它在加入量很少时即能大大降低溶剂的表面张力(或界面张力),改变体系界面,使其形成活化状态,从而产生润湿、乳化、起泡及增溶等一系列的作用,以达到实际应用的要求。表面活性剂种类繁多,结构复杂,其作用不同,应用领域也不同。但从其分子结构角度来看,表面活性剂分子有一个共同     

EVA Copolymer Based Nanocomposites

Nanocomposites are a new class of polymer material with an ultrafine phase dispersion of the order of a few nanometers that shows very interesting properties often very different from those of conventional filled polymers. In this work the mechanical and optical properties of Poly[ethylene‐co‐(vinyl acetate)] (EVA copolymer) based nanocomposites have been investigated to evaluate its possible use in several applications. For example, films for covering greenhouses made by EVA copolymer are appealing because of their interesting optical properties and for the so‐called greenhouse effect. Mechanical properties, and the rigidity in particular, are, on the contrary, quite low. Nanocomposites should avoid this shortcoming if optical properties and processability are not unfavorably effected. EVA copolymer based nanocomposites have been prepared by compounding polymer matrix and two different functionalized silicates (0–10 wt.‐%) in molten state. X‐Ray diffractograms show that the in the adopted experimental conditions no exfoliation of the filler is obtained, but an intercalated morphology is observed. Rheological behavior both in shear and in non‐isothermal elongational flow is only slightly influenced by the presence of the filler. As for the mechanical properties, the elastic modulus strongly increases without any worsening of the elongation at break. The permeability in the UV region is not influenced by adding even relatively high contents of the silicates. The improved mechanical and optical properties and the unmodified processability suggest then the use of these new polymeric systems in many applications and in particular as films for covering greenhouses.

UV spectra of the EVA/Nanofil system.     

Structure‐Based and Fragment‐Based GPCR Drug Discovery

G protein‐coupled receptors (GPCRs) are an important family of membrane proteins; historically, drug discovery in this target class has been fruitful, with many of the world’s top‐selling drugs being GPCR modulators. Until recently, the modern techniques of structure‐ and fragment‐based drug discovery had not been fully applied to GPCRs, primarily because of the instability of these proteins when isolated from their cell membrane environments. Recent advances in receptor stabilisation have facilitated major advances in GPCR structural biology over the past six years, with 21 new receptor targets successfully crystallised with one or more ligands. The dramatic increase in GPCR structural information has yielded an increased use of structure‐based methods for hit identification and progression, which are reviewed herein. Additionally, a number of fragment‐based drug discovery techniques have been validated for use with GPCRs in recent years; these approaches and their use in hit identification are reviewed.     

UV—P衍生的新型光稳定剂研究进展

综述了以紫外线吸收剂UV—P为基础的新型苯并三唑类光稳定剂．包括高相对分子质量型、反应型、多功能型的合成方法和在聚合物中的应用。     

基于CopyCAD的逆向工程

逆向工程是近几年迅速发展起来的一门新兴学科。首先,对需要再设计的产品实物进行三维数字化处理,然后将获得的三维离散数据作为初始素材,借助专用的曲面处理软件和CAD／CAM系统构造实物的CAD模型,输出NC加工指令或用STL文件驱动快速成型机制造出产品或原型。DELCAM以CopyCAD核心的逆向工程解决方案是集逆向工程、CAD／CAM为一体的完整的实现逆向和再设计的完整解决方案。     

Bimetallic Cobalt Based Catalysts

Highly dispersed, oxide- or zeolite-supported bimetallic catalysts are widely used in the catalytic industry, such as in catalytic reforming, nitrogen industry and gas-to-liquid technology. The paper highlights the nano-sized Co-based bimetallic system in terms of correlation between structure and reactivity/selectivity promoted by the second metal. Opposite to the bulk alloys nano-sized bimetallic catalysts are extremely sensitive to the structure, morphology, valence state of the supporting oxide material in which the nano-particles are embedded. In this case, one of the less reducible components, which strongly interact with the supports, may stabilize the second, more noble metals, and thus the latter can be stabilized in highly dispersed state. Conversely, addition of noble metal to the hardly reducible component may facilitate reduction, which causes the retardation of the deactivation process of some hydrocarbon reaction. The future trend is the application of bimetallic nano-particles although careful consideration and experimentation should be taken to elucidate the structure of such type of catalyst. The various effects of Co-based bimetallic particles, such as particle size, metal/support interface, morphology and electronic effects, on the activity/selectivity in given catalytic reactions will be discussed.