六铝酸钙材料的合成及其显微结构研究

分别采用轻质碳酸钙和活性氧化铝 ,或纯铝酸钙水泥和活性氧化铝为初始原料 ,反应烧结合成了六铝酸钙 (CA6)材料 ,研究了原料和成型压力对合成材料的烧结性能和显微结构的影响 ,同时借助于XRD、TG -DSC、SEM和EDAX等测试手段对其反应过程、物相变化和显微结构进行了分析和观察。研究结果表明 :(1) 130 0℃时 ,合成材料的主晶相为刚玉相和CA2 ,并开始有CA6形成 ;温度升至14 0 0℃ ,CA6大量生成 ;15 0 0℃时反应完成 ,产物全部为CA6相。 130 0～ 15 0 0℃时 ,上述反应表现为体积膨胀过程 ,试样的体积密度和径向线收缩率随温度的变化不大 ;而高于 15 0 0℃时 ,试样明显趋向烧结 ,体积密度升高 ,线收缩率加大。采用纯铝酸钙水泥和活性氧化铝合成的试样的体积密度均高于采用轻质CaCO3 和活性氧化铝的 ,尤其在烧成温度高于 15 0 0℃时。坯体的成型压力对这两种合成试样的烧结性能均没有显著影响。 (2 )合成六铝酸钙材料的晶粒形貌与合成工艺有关 ,制备片状晶粒的六铝酸钙材料需满足两个条件 :一是晶核有足够的发育空间 ,二是从晶核生长形成片状结构需足够的物质扩散。采用纯铝酸钙水泥和活性氧化铝为原料的试样 ,其CA6晶核很容易发育成片状晶形 ,且随着坯体成型压力的增加 ,片状CA6有向等轴状发展的趋势 ;采用     

Synthesis and characterization of maltose fatty acid monoesters as biosurfactants

Maltose long-chain fatty acid esters (MFAE), esterified at the 6 and 6′ position, were synthesized with stearic, palmitic, myristic, and oleic groups. Synthesis yields were 15–20% based on initial maltose present, and structural confirmation was obtained using plasma desorption mass spectrometry and nuclear magnetic resonance spectroscopy. These surfactants have surface tensions in the range of 34–36 dyn/cm at their critical micelle concentrations (CMC) of approximately 10⁻⁵–10⁻⁶ mol/L. The increased chain lengths have a marked effect, reducing CMC values for MFAE by approximately three orders of magnitude over similar carbohydrate-based dodecyl chain sources. Within chain lengths between 14 and 18 carbons, the rate of change in CMC is significant and decreases with increasing chain length for MFAE. The melting points of MFAE are approximately 40°C, and the heat capacities range from 1.6 to 1.9 J/g·K. These numbers are comparable to those of sucrose esters, indicating their applicability in similar uses. However, because MFAE, unlike sucrose, possess an anomeric carbohydrate carbon position, these surfactants maintain their reducing nature and are susceptible to further derivatization. They are also synthesized from renewable, economical carbohydrates and lipids and may provide an excellent alternative to pertrochemical-derived products.     

Effect of solution properties on nanofibrous structure of electrospun poly(lactic‐co‐glycolic acid)

Electrospinning of poly(lactic‐co‐glycolic acid) (PLGA) in chloroform or 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) was investigated, focusing on its solution parameters, to develop nonwoven biodegradable nanofibrous structures for tissue engineering. PLGA nanofibers were obtained by electrospinning of 15 wt % PLGA solution and the resulting average fiber diameters were varied with the range of 270–760 nm, depending on solution property. When small amounts of benzyl triethylammonium chloride (BTEAC) was added to the PLGA/chloroform solution, the average diameter was decreased from 760 to 450 nm and the fibers were densely amounted in a straight shape. In addition, the average fiber diameter (270 nm) of nanofibers electrospun from polar HFIP solvent was much smaller than that (760 nm) of nanofibers electrospun from nonpolar chloroform solvent. Therefore, it could be concluded that conductivity or dielectric constant of the PLGA solution was a major parameter affecting the morphology and diameter of the electrospun PLGA fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1214–1221, 2006     

长铝公司含油废水处理工艺

根据含油废水的特性，结合中国长城铝业公司废水处理的现状及水质特点，论述了采用捞油→撇油→隔油→混凝气浮的工艺处理铝冶炼企业含油废水的可行性，并对此工艺进行了剖析。多年的运行经验证明，采用此工艺可去除水中的可浮油与乳化油，去除率可达98％左右。油浓度低于国家污水排放标准10mg／L。此工艺为铝工业废水治理开辟了一条崭新的道路。然而，此工艺在具体设计和运行管理上仍存在一些问题，有待于日臻完善。     

锡偶联型溶聚丁苯胶性能评价

本文研究了具有适宜的苯乙烯、乙烯基含量及其配比的１５立升釜聚合的锡偶联型溶聚丁苯橡胶（Ｓ－ＳＢＲ）的硫化及力学性能、古德里奇疲劳温升、动态力学及摩擦性能，并与低温乳聚丁苯橡胶（Ｅ－ＳＢＲ）进行了平行对比。结果表明，锡偶联型Ｓ－ＳＢＲ是一种集较佳的静态性能、优异的动态性能、令人满意的安全及低能耗性为一体的新型胎面材料。     

Evaluation of a palladinized Nafion™ for direct methanol fuel cell application

Palladinized Nafion™ was prepared via ion-exchange and chemical reduction method. Palladium precursors and solvent systems determined the efficiency of the incorporation and distribution of nanoparticles. The tortuous thin Pd film was formed on the surface of membrane when Na⁺-Nafion™ and water were used. Pd nanoparticles enhanced the water uptake of Nafion™ and reduced its methanol uptake. And dispersed Pd nanoparticles in Nafion™ disturbed the proton conduction and methanol permeation simultaneously in Nafion™ cluster. In order to reduce methanol permeation of Nafion™ and keep its high conductivity, it was more efficient for Pd nanoparticles to distribute near the surface of membrane. Palladinized Nafion™ improved the performance of DMFC single cell operation by reducing the methanol permeation.     

多杀菌素的高效液相色谱法测定

采用高效液相色谱法对Saccharpolyspora spinasa发酵液中多杀菌素含量进行测定。本方法的相对标准偏差为0．11％。变异系数为0．15%．线性相关系数为0．99916．平均回收率为96.94％。     

Thermodynamic Calculation of the Zirconia–Calcia System

An optimal thermodynamic data set for the zirconia–calcia system is evaluated by the CALPHAD (CALculation of PHAse Diagrams) method applied to experimental phase diagram and thermodynamic data. The liquid and C _ss (cubic ZrO₂ solid solution) are described by a subregular solution model. Three compounds, CaZr₄O₉, Ca₆Zr₁₉O₄₄, and CaZrO₃, are modeled as stoichiometric compounds. A regular solution model is applied to the other phases. Comparisons between calculated and measured phase diagrams and thermodynamic quantities show that most of experimental information is satisfactorily accounted for by thermodynamic calculations. The calculations also reasonably predict the measured electromotive force concerning the metastable C _ss.     

空压机组汽轮机排气压力、温度高原因分析及解决方法探讨

1概况 空压机汽轮机组是空分装置原料和动力的提供者,主要由空压机和工业汽轮机两部分组成.汽轮机为注入凝汽式汽轮机,型号NK-32/36/16-3,级数为1冲动级15反动级,功率9022kW,额定转速7270 r/min,主蒸汽压力6.9 Mpa,主蒸汽温度550℃,主蒸汽流量通常31.9t/h,最大36.8t/h,排汽压力通常0.015MPa,最大0.04MPa,排汽温度通常55℃,最大120℃.但由于多种原因,注汽一直未投,平常为全凝汽式运行.