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1.
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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《Polymer》1987,28(5):683-692
After a short survey of the first indications on the existence of stereoregularity in the main chains of the vinyl polymers, the first syntheses of stereoregular poly(vinylethers) and polystyrene are briefly summarized. The difficulties encountered in the early investigations of the propylene polymerization by the CoO/MoO3/Al2O3 and CrO3/SiO2/Al2O3 catalysts are considered and the isolation and identification of a crystalline component in the mixture of diastereomeric macromolecules thus obtained, are discussed. The results obtained by different research groups, independently investigating the stereospecific polymerization of vinyl monomers, are compared and finally an attempt is made to explore the origin of the very rapid progress made in this field by Natta and coworkers in connection with their discovery of the stereospecific polymerization of α-olefins with the ‘Ziegler-Natta catalysts’. 相似文献
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Over the last six years wind power has become the world's fastest growing energy technology, and growth rates of 20% a year are predicted for the next 相似文献
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I. V. Kuz'mitskii 《Combustion, Explosion, and Shock Waves》2004,40(4):467-472
The results of a study of the chemicalreaction zone structure for a number of high explosives (HEs) are discussed. It is found that an increase in the initial density of the HEs leads to a structural change in the chemicalreaction zone involving elimination of the Von Neumann spike at the critical density point. Conversely, as the initial density of the explosive decreases, the ratios of the gasdynamic parameters (in particular, mass velocities) at the Von Neumann point to the same parameters at the Jouguet point increase. It is shown that to explain the indicated regularities, one does not need to invoke the assumption of an increasing contribution of the exothermic decomposition of the HE the shock. The results can be explained within the framework of classical Zeldovich–Von Neumann–Döring theory with an ordinary shock at the detonationwave front and, hence, with a nearly zero contribution to the total energy release in the chemical reaction zone. 相似文献
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《Journal of the European Ceramic Society》2014,34(6):1591-1598
We prepared foam glasses from cathode-ray-tube panel glass and CaCO3 as a foaming agent. We investigated the influences of powder preparation, CaCO3 concentration and foaming temperature and time on the density, porosity and homogeneity of the foam glasses. The results show that the decomposition kinetics of CaCO3 has a strong influence on the foaming process. The decomposition temperature can be modified by varying the milling time of the glass–CaCO3 mixture and thus for a specific CaCO3 concentration an optimum milling time exists, at which a minimum in density and a homogeneous closed porosity are obtained. Under the optimum preparation conditions the samples exhibit a density of 260 kg/m3. The thermal conductivity of the foam glass was measured to be 50–53 mW/(m K). The observed dependence of the foaming process on the decomposition kinetics of the foaming agent can be applied as a universal rule for foaming processes based on thermal decomposition. 相似文献
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Please click here to find the Letter to the Editor to which this Response refers: http://dx.doi.org/10.1080/02786826.2012.684412 Copyright 2012 American Association for Aerosol Research 相似文献
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《Diamond and Related Materials》2001,10(9-10):1602-1606
We have studied the effect of chromium concentration in alloys of the Co–Fe system on their interaction with graphite at p, T parameters of thermodynamic stability of diamond. It has been found that addition of chromium to the alloys stabilizes the Me3C-type carbide, as a result, the structure of a layer of a contact melting at the alloy–graphite interface is identical to a horizontal section of the metastable phase diagram of the Fe–C system. It is shown that addition of chromium to the Co–Fe–C system lowers the eutectic melting temperature by 80–100 K. In this case, the coefficient of carbon diffusion in the melt increases by ∼20–30%. An increased surface activity of a Cr-containing melt with respect to graphite is noted, which is the reason of intensive intrusion of the melt deep into a graphite layer along the grain boundaries. As a result, the number of nucleating diamond crystals and the degree of the graphite→diamond transformation increases. 相似文献
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Miloslav Bohdanecký 《Polymer Bulletin》1993,31(1):117-122
Summary Critical values of the polymer volume fraction 2,c and the interaction parameter c have been computed for the case that the equation for the chemical potential of solvent contains terms c
2
3
and c
2
4
in addition to
2
2
. For 0 c 1/3, the limits for infinite chain length are
2,c
= 0 and
c
= 0.5. Quite different results are obtained for c > 1/3,
2,c
being finite and
c
lower than 1/2. Conclusions for the estimation of the temperature and the entropy-of-dilution parameter are discussed. 相似文献
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Leszek Stobinski Hong-Ming Lin 《过程工程学报》2004,4(Z1):493-495
Careful preparation of the iron nano-particle catalyst for carbon nanotubes (CNTs) fabrication has crucial importance for initial growth of multi-wall carbon-nanotubes (MWCNTs). Thin iron layer was thermally deposited in a high vacuum onto the surface of the SiO2/Si wafer at about 300 K. The sample was heated up to 700℃ in a hydrogen atmosphere, and then the sample was heated once again at750℃ in ethylene atmosphere. After hydrogen treatment continuous Fe layer was changed into many well separated Fe nano-peaks. AFM, SEM and HR-TEM studies of deposited MWCNTs allow us to propose a growth mechanism for long, straight MWCNTs. 相似文献
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Vitaliy Kholodnyy Borys Dzyuba Marek Rodina Hermes Bloomfield-Gadêlha Manabu Yoshida Jacky Cosson Sergii Boryshpolets 《International journal of molecular sciences》2021,22(17)
The fertilization of freshwater fish occurs in an environment that may negatively affect the gametes; therefore, the specific mechanisms triggering the encounters of gametes would be highly expedient. The egg and ovarian fluid are likely the major sources of these triggers, which we confirmed here for rainbow trout (Oncorhynchus mykiss). The ovarian fluid affected significantly spermatozoa performance: it supported high velocity for a longer period and changed the motility pattern from tumbling in water to straightforward moving in the ovarian fluid. Rainbow trout ovarian fluid induced a trapping chemotaxis-like effect on activated male gametes, and this effect depended on the properties of the activating medium. The interaction of the spermatozoa with the attracting agents was accompanied by the “turn-and-run” behavior involving asymmetric flagellar beating and Ca2+ concentration bursts in the bent flagellum segment, which are characteristic of the chemotactic response. Ovarian fluid created the optimal environment for rainbow trout spermatozoa performance, and the individual peculiarities of the egg (ovarian fluid)–sperm interaction reflect the specific features of the spawning process in this species. 相似文献
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John Stanley 《Lipid Technology》2010,22(2):39-41
The evidence for the lipid hypothesis is weak. After 20 years of follow‐up, the Nurses Health Study, a prospective cohort study, was no longer able to demonstrate an association between intakes of saturated fat and risk of developing coronary heart disease. Randomised controlled trials with statins have shown that lowering LDL‐cholesterol levels by 23% can reduce the risk of developing cardiovascular disease but reducing saturated fat can only reduce cholesterol levels by 10%. This issue can only be resolved by carrying out randomised controlled dietary trials with CVD endpoints. Although there are scientific difficulties standing in the way of such trials, it is the opinion of this author that these can be overcome. Whether there is the political will to fund them is another matter although some of the money currently spent on prospective cohort studies would be far better spent on randomised controlled trials. 相似文献
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The effect of the location of the initiation point on explosionfield parameters is studied numerically using as an example the detonation of a stoichiometric mixture of propane with air. The shape of the cloud of the mixture (toroid) and the ratio of its dimensions in calculations are typical of the volumes of air–fuel mixtures formed in accidents. The effect of the initiation point location within the cloud cross section was studied with variation in the position of the lower edge of the cloud above the underlying surface. 相似文献
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B. K. Nefedov 《Catalysis in Industry》2012,4(1):83-88
Ways of developing and modernizing Russian oil refineries are considered on the basis of an analysis of the presentations
of Russian and foreign companies at the 10th Russian and CIS Refining Technology Conference (RRTC) held by Euro Petroleum
Consultants in Moscow on September 23–24, 2010. It is shown that the main trends in the development of the Russian oil refining
industry with the purpose of overcoming the current economic crisis are the rational use of production facilities, the modernization
of existing plants to increase the depth of processing and the profitability of production, satisfying the growing demand
for motor fuels (especially diesel) and improving their quality to meet the parameters of eurostandards, increasing the conversion
of the processing of oil at oil refineries, reducing the consumption of energy, and improving the process control and optimization
systems at existing plants to increase their efficiency and minimize the environmental risks in operating plants. The development
of hydrogenation processes that allow the synthesis of high-quality products from cheap sour crude oil or the qualified preparation
of raw materials for the process of catalytic cracking must now become the main direction of oil refining in Russia and CIS
countries. Oil residue processing technologies (e.g., hydrogenation processes, catalytic cracking, new and improved catalysts
for hydrocracking, catalytic cracking, hydrotreatment of heavy oil residues; and hydrogen synthesis technologies) are discussed. 相似文献
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《Chemical engineering science》1985,40(7):1245-1250
Introducing an “on-line” Coulter Counter measurement technique in a stirred fluidized bed of KAl(SO4)2·12H2O crystals in order to observe the generated secondary nuclei leads to results. But even these results still do not give an answer to the complicated phenomena of birth and growth of the secondary nuclei.The results are the following:Secondary nuclei of sizes smaller than 2 μm are generated and the smaller the size the higher the number of the generated nuclei.Nuclei below about 3 μm seem not to be “effective”. The high number of particles in the unfiltered “pure” solution prior to the experiment does not grow in the sampling cells. The number of nuclei grown in the sampling cells corresponds to the number of nuclei above 3 μm counted by the Coulter Counter. There are particles growing more slowly in the sampling cells, but the number is much smaller than the number of particles below 3 μm counted by the Coulter Counter. This means some of these particles do not grow or they grow at very slow rates or something else happens to them.The higher the supersaturation the more nuclei are generated. The effect of supersaturation at high stirrer speeds is the least with the small nuclei, but the strongest with the larger nuclei sizes. That means more nuclei can be found in larger size ranges at high supersaturations and high stirrer speeds.The higher the stirrer speed the more nuclei are generated.The power number found for the supersaturation 1.3 fits well into the range of 1.3–1.6 given by former work. 相似文献
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V. Sh. Shagapov A. S. Chiglintseva G. R. Rafikova 《Theoretical Foundations of Chemical Engineering》2018,52(4):560-567
The problem of methane hydrate formation when the process is controlled by gas diffusion in the hydrate layer formed at the gas–ice (or water) interface is solved. It is shown that an approximate quasi-stationary solution of the diffusion equation is in good agreement with its numerical solution over a wide range of the solubility of the gas in the hydrate, which is dependent on pressure. It is found that the time for the complete transition of the water (or ice) phase into the hydrate state decreases with an increase in the saturation concentration of the mobile gas in the hydrate. The kinetic equations derived based on a quasi-stationary solution of the diffusion equation, which are relationships for the intensity of hydrate formation in snow-containing (or water-containing) formations during the filtration of hydrate-forming gases, are used to describe the concentration fields of the diffusing gas and the dynamics of hydrate layer growth. 相似文献