低引气性聚羧酸类高效减水剂的制备及其性能研究

借助高分子材料分子设计理论和大分子单体制备技术 ,利用消泡剂领域的研究成果 ,设计并合成了一种可以聚合的具有消泡功能的大分子单体 ,采用水溶液共聚工艺 ,合成了一种具有低引气、高保坍性能的高效聚羧酸类减水剂。试验结果表明 ,在共聚物单体中引入单体总量0.4%mol左右的功能性大分子单体 ,共聚物在混凝土中的含气量将大幅度降低 ,产品在低掺量(水泥质量的0.2%)的情况下 ,不但有很高的分散性能 ,而且具有良好的流动保持能力。

聚羧酸减水剂酸醚比对其引气性能的影响

通过水溶液自由基聚合法合成了一系列不同酸醚比的聚羧酸减水剂,研究了不同酸醚比的聚羧酸减水剂对新拌水泥浆体含气量、流变性以及水泥砂浆分级气泡含量的影响.结果表明:随着酸醚比的增加,聚羧酸减水剂分散性能及引气性能显著增加,其中当丙烯酸与异戊烯醇聚氧乙烯醚(TPEG)单体摩尔比达到4∶1时,聚羧酸减水剂分散性能及引气性能均达到较大值,随着酸醚比的进一步增加,聚羧酸减水剂分散性能与引气性能呈下降趋势;随着酸醚比的增加,聚羧酸减水剂在水泥颗粒表面的吸附能力增加,使得水泥颗粒表面的聚羧酸分子浓度增加,降低了水泥颗粒-水的固-液界面能;聚羧酸减水剂能够显著改善砂浆气泡孔径分布,在引入大量中小气泡的同时降低大孔径气泡的占比,使得气泡孔径分布更加细小化;同时,随着聚羧酸减水剂主链中酸醚比的增加,引入的小气泡占比呈下降趋势,大孔占比呈上升趋势.

橡胶粉改性水泥混凝土引气性能试验分析的研究

通过利用细度分别为20、40、60目橡胶粉颗粒以0、1.0%、2.0%、3.5%、5.0%、6.0%替代同质量砂配制成的橡胶粉水泥混凝土分别进行表观密度及新拌橡胶粉水泥混凝土含气量试验分析,试验结果表明当橡胶粉替代量小于3.5%时,橡胶粉的细度对橡胶粉水泥混凝土表观密度和含气量变化影响较小;当橡胶粉替代量大于或等于3.5%时,随着橡胶粉细度目数的增加,新拌橡胶粉水泥混凝土就越密实,其内部含气量就越小,表观密度就越大。综合橡胶水泥混凝土其他研究和性价比结果,建议工程应用上采用橡胶粉掺量3.5%左右为最佳。

聚羧酸系减水剂的分散作用及其引气性能(英文)

采用自由基聚合法合成了一系列聚羧酸减水剂,通过正交试验研究了减水剂官能团种类及比例,引发剂、链转移剂对其在水泥浆中分散性能的影响。在此基础上,通过优化官能团比例及调整分子量合成了一种引气性低且分散性高的聚羧酸系减水剂。分析了官能团比例和分子量对聚羧酸系减水剂引气性能的影响,探讨了分子量及其分布与聚羧酸系减水剂的分散性能及其饱和掺量的关系。结果表明:合适的官能团比例是降低聚羧酸系减水剂引气性的前提。官能团比例合适时,分子量过高将导致其引气性增强,聚羧酸系减水剂在水泥净浆中的分散性低,且在水泥砂浆中的饱和掺量高。

基于功率保持的辅助动力装置引气性能计算模型

以带负载压气机辅助动力装置(APU)为对象,分析了其结构特点与工作原理,针对目前工程上常用的APU引气性能计算模型的不足,建立了基于APU与空气涡轮匹配的总体性能数学模型和负载压气机变几何部件特性插值模型。在此基础上,研究了APU功率调节规律,获得了轴功率负载、APU涡轮前温度、排气温度与负载压气机进口导叶角度之间的匹配关系,进而实现了APU全包线内和全工况下的引气性能计算。利用GTCP131-9A试验数据对模型进行了验证,结果表明:引气流量计算误差小于3%,引气压力计算误差小于4%;功率保持下的APU涡轮前温度限制值仅与轴功率负载大小有关,与进气温度无关。研究结论对于带负载压气机APU总体性能计算和调节规律设计提供了参考。

聚羧酸系减水剂研究与应用新进展

本文首先回顾了聚羧酸系减水剂在我国的快速发展历程,并梳理了聚羧酸系减水剂用聚醚大单体的种类和发展方向。在聚羧酸系减水剂的制备技术方面,提出了低温制备技术是今后的研究发展方向。进而介绍了聚羧酸系减水剂在功能化和系列化方面的新进展,分析了粉状减水剂制备技术存在的问题和解决措施。在应用技术方面,克服粘土对聚羧酸系减水剂应用性能的影响是目前面临的重要问题,聚羧酸系减水剂在预制构件应用技术研究还处于初始阶段。

聚羧酸减水剂聚醚大单体的研究进展及展望

聚羧酸系减水剂是一种新型环保的减水剂,是国内外减水剂研究的热点。介绍了聚羧酸系减水剂大单体的种类及特点,围绕聚羧酸减水剂分子结构的可设计性,可通过引入功能化的聚醚单体,开发具有减缩性、低引气性和早强的功能化产品,以满足工程需求。

聚羧酸减水剂应用中的几点理解误区

当前,聚羧酸减水剂的应用缺乏成熟的理论和经验指导,应用者存在一些理解上的误区。文章对聚羧酸减水剂的水泥适应性、敏感性及引气性能等方面给出了分析和理解,以期对聚羧酸减水剂的推广应用有些许指导和借鉴作用.

Holographic Gas as Dark Energy

We investigate the statistical nature of holographic gas, which may represent the quasi-particle excitations of a strongly correlated gravitational system. We find that the holographic entropy can be obtained by modifying degeneracy. We calculate thermodynamical quantities and investigate stability of the holographic gas. When applying to cosmology, we find that the holographic gas behaves as holographic dark energy, and the parameter c in holographic dark energy can be calculated from our model. Our model of holographic gas generally predicts c 〈 1, implying that the fate of our universe is phantom-like.

Effect of breathing and Daoyin exercises on the quality of life in patients with chronic obstructive pulmonary disease

Objective： To observe the effect of breathing and Daoyin exercises on the quality of life in patients with stable chronic obstructive pulmonary disease（COPD） due to deficiency of the lung and kidney（grade II-III）.Methods： A total of 60 eligible cases were randomly allocated into a treatment group（n=30） and a control group（n=30） by random number table. Cases in the control group received routine Western medical treatment, whereas cases in the treatment group conducted breathing and Daoyin exercises in addition to routine Western medical treatment. Patients in both groups were treated for a total of 3 months. Then the observation was made on changes in pulmonary ventilation function, major clinical symptoms, modified Medical Research Council scale（m MRC）, distance in 6-minute walk test（6-MWT）, COPD assessment test（CAT） and efficacy satisfaction questionnaire for COPD（ESQ-COPD） before and after treatment. Results： After treatment, the total effective rate was 80.0% in the treatment group, versus 66.7% in the control group, showing a statistical difference（P〈0.05）. Patients in the treatment group obtained more significant improvement in coughing, sputum production, dyspnea and shortness of breath than those in the control group（P〈0.05）. Patients in the treatment group obtained more significant elevation in the forced expiratory volume in 1 second percentage of predicted value（FEV1%） and peak expiratory flow rate（PEF%） than those in the control group（P〈0.05）. Patients in the treatment group obtained lower m MRC score than those in the control group（P〈0.05）. Patients in the treatment group obtained longer 6-MWT distance than those in the control group（P〈0.05）. Patients in the treatment group obtained lower CAT score（P〈0.01） and higher ESQ-COPD score（P〈0.05） than those in the control group. Conclusion： Breathing and Daoyin exercises combined with routine Western medical treatment are effective for stable COPD（grade II-III） due to deficiency of the lung and kidney and can improve the patients＇ quality of life.

A successful treatment of traumatic bronchobiliary fistula by endoscopic retrograde biliary drainage

Bronchobiliary fistula（BBF）is a rare condition in which there is a nonnatural communication between the biliary tract and the bronchial trees.It is usually aroused by the complications of hepatic hydatidosis,hepatic amebic,biliary obstruction,trauma,neoplasm and hepatic abscess formation.In this paper,we described a patient suffering from BBF that is secondary to trauma or surgery.Especially,BBF was detected in the left lung.Finally,we managed this case successfully without an open surgery.

High yield fabrication of semiconducting thin-film field-effect transistors based on chemically functionalized single-walled carbon nanotubes

Here we report a simple and scalable method to fabricate high performance thin-film field-effect transistors(FETs) with high yield based on chemically functionalized single-walled carbon nanotubes(SWNTs) by organic radical initiators.The UV-Vis-NIR spectra,Raman spectra and electrical characterization demonstrated that metallic species in CoMoCat 65 and HiPco SWNTs could be effectively eliminated after reaction with some organic radical initiators.The effects of the substrate properties on the electrical properties of FET devices were investigated,and the results showed that the electrical properties of FET devices fabricated on high hydrophobic substrates were better than those on low hydrophobic substrates.Furthermore,it was found that FET devices based on 1,1'-azobis(cyanocyclohexane)(ACN)-modified CoMoCat 65 SWNTs exhibited more excellent electrical performance with effective mobility of ～11.8 cm2/Vs and on/off ratio of ～2×105 as compared with benzoyl peroxide(BPO)-modified CoMoCat 65 SWNTs and lauoryl peroxideand(LPO)-modified HiPco SWNTs,likely due to the introduction of the electron-withdrawing groups(CN group) on the SWNT surface.This method does not require nontrivial reaction conditions or complicated purification after reaction,therefore promising low-cost production of high-performance devices for macroelectronics.

Anisotropic Bianchi Type Ⅰ Cosmological Models with Generalized Chaplygin Gas and Dynamical Gravitational and Cosmological Constants

This paper deals with study of generalized Chaplygin gas model with dynamical gravitational and cosmological constants. In this paper a new set of exact solutions of Einstein field equations for spatially homogeneous and anisotropic Bianchi type Ⅰ space-time have been obtained. The solutions of the Einstein's field equations are obtained by considering(i) the power law relation between Hubble parameter H and scale factor R and(ii) scale factor of the form R =-1/t + t^2, t > 1. The assumptions lead to constant and variable deceleration parameter respectively. The physical and dynamical behaviors of the models have been discussed with the help of graphical representations. Also we have discussed the stability and physical acceptability of solutions for solution type-Ⅰ and solution type-Ⅱ.