共查询到20条相似文献,搜索用时 31 毫秒
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The transport properties of ionic liquids (ILs) are crucial properties in view of their applications in electrochem-ical devices. One of the most important advantages of ILs is that their chemical–physical properties and conse-quently their bulk performances can be well tuned by optimizing the chemical structures of their ions. This will require elucidating the structural features of the ions that fundamentally determine the characteristics of the nanostructures and the viscosities of ILs. Here we showed for the first time that the“rigidity”, the order, and the compactness of the three-dimensional ionic networks generated by the anions and the cation head groups determine the formation and the sizes of the nanostructures in the apolar domains of ILs. We also found that the properties of ionic networks are governed by the conformational flexibility and the symmetry of the anion and/or the cation head group. The thermal stability of the nanostructures of ILs was shown to be con-trolled by the sensitivity of the conformational equilibrium of the anion to the change of temperature. We showed that the viscosity of ILs is strongly related to the symmetry and the flexibility of the constitute ions rather than to the size of the nanostructures of ILs. Therefore, the characteristics of the nanostructures and the viscosities of ILs, especially the thermal stability of the nanostructures, can be fine-tuned by tailoring the symmetry and the conformational flexibility of the anion. 相似文献
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Investigation of the effects of fatty acids on the compressive strength of the concrete and the grindability of the cement 总被引:1,自引:0,他引:1
In cement industry, a great energy consumption has been observed during grinding of clinker. To reduce this consumption, some waste products have been used as grinding aids.In this investigation, the effects of sunflower oil (SO), oleic acid (OA), stearic acid (SA), myristic acid (MA) and lauric acid (LA) on the fineness and strength of the cement have been examined. These aids were added into clinker in certain ratios based on the cement clinker weight and the grinding has been done for a definite time at the same condition.All of the fatty acids used increased the fineness as compared with the cement without the grinding additives. SO and OA decreased the strength significantly, LA decreased it to a lesser extent and SA increased it definitely according to the common cement. But MA did not alter the strength of the cement as much as SA. In addition, the covering of the balls influences the grinding of cement clinker unfavourably. 相似文献
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Polyurethaneureas (PUU), which were synthesized from 4,4′-diphenylmethane diisocyanate (MDI), poly(ethylene glycol) (PEG), and 3,5-diaminobanzoic acid (DABA), were used as polyelectrolytes in this study. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to monitor the effect of the various kinds of PEG on the changes in morphology of PUU electrolytes corresponding to the concentration of lithium perchlorate (LiClO4) dopants. The results of DSC and FT-IR indicate the Li+ ions coordinate with the soft and hard segments. Additionally, the crystallinity of the PEG soft segment and the ordered hydrogen-bonded urea carbonyl groups decreased with increasing salt concentration. Impedance spectroscopy (IS) measurements show that the PUU electrolyte with the high phase separation degree has the high ionic conductivity. The hard-segment Tg and the soft-segment Tm influence the conductivity behavior of polyelectrolytes with increasing measurement temperature. 相似文献
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In spinning basalt fibres, the drafting force is in the same range as in spinning of glass fibres. The effect of the drafting
force can not be considered in the calculation for the strength and rigidity of the bottom of the spinneret.
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Translated from Khimicheskie Volokna, No. 5, pp. 47–50, September–October, 2007. 相似文献
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组合凹模的应力分析是一个非常复杂的问题,对其进行精确分析是解决模具寿命的关键。本文采用有限元分析软件Ansys对转子的组合凹模进行了分析,为转子组合凹模的优化设计提供了依据。 相似文献
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以气煤、肥煤、焦煤、瘦煤为样煤,进行了样煤的粉碎、有机溶剂溶胀和硝酸氧化处理,考察了处理后煤样中的药用腐植酸得率。结果表明,吡啶和N,N-二甲基吡咯烷酮是溶胀较好的溶剂;样煤粉碎后,随着粒度的减小,煤的溶胀率增加;粒度粉碎至200目的气、肥煤经吡啶溶胀和硝酸氧化后,煤样的药用腐植酸得率可达到73.0%和71.4%,而经甲醇溶胀和硝酸氧化的200目气煤药用腐植酸得率为56.4%和58.4%。实验结果表明,煤样经过溶胀和硝酸氧化处理,对药用腐植酸的提取有促进作用。 相似文献
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G. N. Leonov 《Combustion, Explosion, and Shock Waves》2008,44(5):547-551
This paper considers the mechanisms involved in the effect of the unconnected porosity of the condensed phase of nitrocellulose
propellants on the linear burning rate with a pressure rise. A model based on experimental data is proposed for the variation
in the linear burning rate taking into account the compaction of the fuel cells resulting in a nonlinear dependence of the
burning rate on pressure. The temperature coefficient of the linear burning rate is found to exhibit a nontrivial behavior
under pressure rise conditions in various ranges of initial temperatures.
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Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 5, pp. 58–63, September–October, 2008. 相似文献
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流体流动诱导微胶囊膜起皱和变形是一个普遍存在的现象。针对这一现象已有一些模拟和实验研究,但是对于微通道内不同因素对于微胶囊褶皱情况的影响以及褶皱的存在对于微胶囊实际膜面积和粒径的影响等方面却鲜有探讨。针对这一问题,本文制备了具有褶皱膜的聚酰胺微胶囊,并提出通过溶剂浸泡法将微胶囊膜褶皱伸展开,以分析微胶囊的实际膜面积和实际粒径。同时,定义了褶皱度的概念,将抽象的褶皱情况数值化,使分析更为方便。最终,通过研究分析发现,由于与流体剪切力正相关,流体流量和黏度的增大会导致微胶囊褶皱度增加;当这两者固定时,微胶囊粒径的改变对其褶皱度基本无影响。在应用方面,微胶囊壁面褶皱情况的分析为制备单核双壁式微胶囊提供了一种新思路。 相似文献
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Igor G. Medvedev 《Electrochimica acta》2008,53(22):6545-6558
Effect of the density of the electronic states at the valence orbital of the bridge redox molecule on the dependence of the tunnel current on the overvoltage and on the width at half maximum of the current-overvoltage curve is studied. A number of the approximate expressions for the density of states, the tunnel current and the width are obtained in the fully adiabatic limit for different particular cases. It is shown that at small values of the coupling of the electronic levels of the electrodes with the valence orbital of the redox molecule and the small values of the bias voltage two regions of the reorganization Gibbs energy exist with different dependence of the width on the reorganization Gibbs energy. The results of calculations of the density of states, the tunnel current and the width are presented and used for the interpretation of the experimental data [N.G. Tao, Phys. Rev. Lett. 76 (1996) 4066, I. Visoly-Fisher, K. Daie, Y. Terazono, C. Herrero, F. Fungo, L. Otero, E. Durantini, J.J. Silber, L. Sereno, D. Gust, T.A. Moore, A.L. Moore, S.M. Lindsay, PNAS 103 (2006) 8686]. 相似文献