Surfactant behavior and its influence on the viscosity of associative thickeners solutions, thickened latex dispersions, and waterborne latex coatings

Surfactants, varying in their chemical composition and hydrophobic behavior, are used in the formulation of a waterborne coating. These differences influence their aggregation in micellar structures, their interaction with associative thickeners, and in particular, the synergies present in their competitive adsorptions on the disperse phases in a waterborne coating. Adsorption of HEUR thickeners on latexes and the ability of surfactants to displace them from those surfaces is an important variable in the dispersion’s viscosity. With large particle latexes, viscosity increases arise primarily from the network built through the interaction of HEURs with surfactants in the aqueous phase. Fluorescence is used to verify the mechanism by which surfactants enhance associative thickener viscosities. That is best achieved with nonionic surfactants, because of their synergies with large hydrophobe HEURs at low concentration. With decreasing latex particle size the adsorbed species is an important contributor to the dispersion’s viscosity through its contribution to the latex’s effective volume fraction increase and when the size of the adsorbed HEUR is matched to the separation distances of the latex at 0.25 volume fraction. Achieving controlled shear-thinning behavior in small particle size latex paints with the economic constraints on the amount of HEUR required to obtain 90 KU viscosities are discussed. Presented at the 80th Annual Meeting of the Federation of Societies for Coatings Technology, October 30–November 1, 2002, in New Orleans, LA. Polymer and Coatings Dept., Fargo, ND 58103.     

基于防水墙系统的信息安全与保密解决方案

一、引言防火墙、IDS、内外网隔离以及其它针对外部网络的访问控制系统,可有效防范来自网络外部的进攻,但对于企业内部的信息保密问题,却一直没有好的防范方法:内部人员可以轻松地将计算机中的机密信息通过网络、存储介质和打印等方式泄露出去,一旦这些敏感信息、重要数据、设计图纸等流失到敌对势力、竞争对手手中,将给国家、企、事业单位造成重大损失。特别是军工行业、政府机关、承担国家敏感课题的科研部门,涉及到更多的国家机密,对于涉密信息采取严密的防护措施更是显得尤为必要。目前,国家制定了很多相关规章制度,明确规定,这些企事…     

小浪底水库坝前漏斗区泥沙测验分析

小浪底水库坝前漏斗区的形成和发展,直接影响到枢纽建筑物的安全运行。为了保持塔前“门前清,”掌握坝前漏斗区的形成和发展,保证水库进入拦沙后期和正常运用期的正常运用,对坝前漏斗区进行了泥沙测验分析。结果表明:目前漏斗区范围内纵向坡度较缓,尚没有明显的漏斗形成,仅在坝前和塔前200m×1000m范围形成了漏斗雏形。     

Accuracy of teacher judgments in predicting oral reading fluency.

The relationship between teachers' judgments versus actual performance on curriculum-based measures in reading was examined. A total of 30 regular education teachers were asked to predict the oral reading fluency score of students along with a rating scale of reading subskills. Correlations between teacher judgment measures and student performance found that teachers were accurate reporters of student performance levels in reading. However, some questions were raised whether teachers were accurate at predicting the actual level of student oral reading fluency when effect sizes were used to compare teacher judgment and actual student performance. Recommendations for continued research in understanding the parameters of the accuracy of teacher judgment are made. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A novel automated image analysis method for maceral analysis

A new image analysis technique has been developed which allows maceral analysis of coal to be carried out. The technique is able to separate the liptinite component from the background resin by using two separate images of the surface captured with different camera exposure times. At normal exposure, the liptinite has a similar grey scale value to the surrounding resin, but at a higher exposure time, the resin remains black whilst the liptinite grey scale increases significantly enough to distinguish it from the resin. The method has been tested for repeatability and reproducibility and found to be within the ISO Standard requirements.     

High-performance liquid chromatography of human milk triacylglycerols and gas chromatography of component fatty acids

Human milk triacylglycerols were separated by high-performance liquid chromatography. A 5-μ Supelcosil LC-18 column (Supelco, Inc., Bellefonte, PA) was used with acetone/acetonitrile (64∶36, vol/vol) as mobile phase. Triacylglycerols were tentatively identified based on theoretical carbon number and relative retention time. Despite changes resulting from dietary fat variation, the major component triacylglycerols were those composed of palmitic, oleic and linoleic acids. Triacylglycerols with palmitic, stearic and oleic acids were present as minor components. Fatty acids were quantified by gas chromatography relative to an internal standard. Ratios of n−6/n−3 fatty acids were found to be high than previously reported. Based on a paper presented at the Symposium on Milk Lipids held at the AOCS Annual Meeting, Baltimore, MD, April 1990.     

The Smoking Consequences Questionnaire-Adult: Measurement of smoking outcome expectancies of experienced smokers.

The original Smoking Consequences Questionnaire (SCQ; T. H. Brandon & T. B. Baker, 1991) measured college students' outcome expectancies for cigarette smoking. A version (SCQ-Adult) was needed for assessing expectancies in more typical, older, nicotine-dependent smokers. Two separate versions of the SCQ were developed and compared. Tests of construct validity provided greater support for the version comprising probability items over the version comprising subjective expected utility items. As expected, principal components analyses revealed a greater number of factors than the original SCQ suggesting that expectancies become more specific with smoking experience. All scales showed good reliability. Over the course of smoking cessation treatment, expectancies became less positive, especially for abstaining participants. Other validity tests also tended to be consistent with research on alcohol expectancies and with contemporary models of drug outcome expectancies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Long fiber reinforced polyamide and polycarbonate composites. II: Fatigue behavior and morphological property

Fatigue behavior and morphology of long glass fiber reinforced semicrystalline polyamide (nylon 6,6) and amorphous polycarbonate (PC) composites were investigated. The fiber length distribution in the molded samples was calculated by image analyzer. The tension-tension fatigue loading tests at various levels of stress amplitudes were studied. The two-parameter Weibull distribution function were applied to obtain the statistical probability distribution of experimental data. A good correlation existed between the experimental data and the Weibull distribution curves. Straight line S? N curves of long glass fiber reinforced semicrystalline polyamide and amorphous polycarbonate composites at various probabilities were established. The stiffness of the composite under tension-tension fatigue loading was measured. The thermal stress history was also investigated by thermo-imaging techniques during fatigue life testing. Further, failure morphology was examined by scanning electron microscopy (SEM). The results showed that the fracture behavior of the ductile damage in polyamide is different from the brittle damage in polycarbonate.     

重力坝深(底)孔断面钢筋混凝土模型试验研究

文通过7个小尺寸和1个大尺寸的钢筋混凝土断面模型试验，研究重力坝深(底)孔在坝体自重和内水压力以及超内水压力作用下的结构特性和破坏规律。重点探讨混凝土和钢筋应力应变、混凝土开裂、裂缝宽度和裂缝扩展规律，为建立更为科学的孔口配筋理论提供依据。