The role of the symmetry and the flexibility of the anion on the characteristics of the nanostructures and the viscosities of ionic liquids☆

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.     

Dependence of the Time‐Space Structure of the Chemical‐Reaction Zone on the Initial Density of the Explosive

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.     

Parametric Analysis of the Simplest Model of the Theory of Thermal Explosion—the Zel'dovich—Semenov Model

Parametric analysis is performed for the Zel'dovich–Semenov model, a basic model of the theory of thermal explosion that describes the dynamics of an exothermic reaction with arbitrary kinetics in a continuous stirred tank reactor. Particular attention is given to the cases of first and nthorder reactions, oxidation reaction, and reaction with arbitrary kinetics. Parametric dependences of steady states on dimensionless parameters, curves of multiplicity and neutrality of steady states, and parametric and phase portraits of the system are constructed. Regions of multiple steady states and selfoscillations and a region of technological safety are distinguished.     

Effect of the fractional composition of the solid components of coal–water fuel on the characteristics of ignition and combustion

The experimental results of studies of the ignition and subsequent combustion processes of the single drops of organic coal–water fuels (OCWFs) arranged on the junction of a quick-response thermocouple (thermal inertia, <1 s) in an atmosphere of heated (600–1000 K) air are presented. The particles of 2B brown coal and D coal, water, and oils of different types (turbine, motor, and transformer oils) were used as the main OCWF components. The effect of the degree of grinding (fineness) of the solid fuel components of OCWFs on the following integral characteristics of the ignition and combustion of prepared fuel compositions was established: the delay times of ignition and complete combustion. A decrease in the delay times of ignition and complete combustion with decreasing the degree of grinding was detected (in a range of 40–200 μm used as an example). The reasons and special features of the influence of this factor on the integral characteristics of the test processes were recognized.     

Influence of the temperature dependence of the thermophysical properties of coal–water fuel on the conditions and characteristics of ignition

The results of an experimental study and mathematical simulation of the ignition of coal–water fuel (CWF) particles, the main thermophysical characteristics of which (thermal conductivity (λ), heat capacity (C), and density (ρ)) depend on temperature, are reported. Based on the results of the numerical study, the influence of changes in the thermophysical properties upon the heating of the main bed of fuel on the conditions and characteristics of its ignition was analyzed. The ignition delay times (t _i) of CWF particles were determined under the typical furnace conditions of boiler aggregates. As a result of the mathematical simulation of the process of CWF ignition, it was established that the temperature dependence of thermophysical characteristics can exert a considerable effect on the characteristics and conditions of ignition. In this case, it was found that the ignition of coal–water drops is possible under the conditions of their incomplete dehydration. A good agreement of the theoretical ignition delay times of the CWF particles and the experimental values of t _i was established.     

the determination of rig

per or not. For many years, scientists in the world have done a lot of research work in this field. As opinions vary, no unanimous conclusion can be drawn.In this paper, the physical concept of each items in rigidity is analysed first, an     

Effect of Self-Assemblies on the Dynamics of the Briggs–Rauscher Reaction

The study involves the dynamic evolution of the Briggs–Rauscher (BR) reaction in the presence of various surfactants—SDS (sodium dodecyl sulphate) as anionic, CTAB (cetyl trimethylammonium bromide) as cationic and TritonX‐100 [4‐(1,1,3,3‐(tetramethylbutyl) phenyl polyethylene glycol] as a neutral one in single as well as mixed mode conditions (SDS + TX‐100 and CTAB + TX‐100). The reaction has been monitored potentiometrically at 30 °C under CSTR conditions. These surfactants affect the reaction dynamics to an extent which depends on the nature and concentration of the surfactant and the formation of their self‐assemblies. The experimental findings indicate that the oscillatory behavior of the BR reaction in the presence of surfactants is due to the efficacy of organized surfactant assemblies to selectively distribute the key species involved in the reaction, and their interaction with the counter ions in cases of ionic micelles. The study reveals that the evolution of oscillatory behavior is a characteristic feature of the surfactant.     

Effect of the processing on the production of cordierite–mullite composite

In this study, effect of process on the production of cordierite–mullite composite was studied. For this reason two different processing methods were used in the production of cordierite–mullite composites. In first process, in situ cordierite–mullite composites were produced from cordierite and mullite layers which were formed by using aqueous tape casting method. In second one, composite was produced by addition of pre-produced mullite powders (in different weight percents, 0–30) into cordierite starting powders. The results show that the addition of pre-sintered mullite powders to the cordierite slip has more effect on densification behavior and mechanical properties of composites than layered production method.     

Effect of the Mesostructuration of the Beta Zeolite Support on the Properties of Cobalt Catalysts for Fischer–Tropsch Synthesis

The effect of mesostructuration of beta zeolite and of metal loading on the properties of cobalt-based catalysts for Fischer–Tropsch synthesis was studied in this work. The most active catalyst was the mesostructured beta zeolite-supported cobalt (10%), which also showed a low selectivity to methane and the lowest olefin/paraffin ratio.     

Wind energy — the fuel of the future

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     

Modernization of oil refineries as the basis for the development of the Russian oil refining industry in the period of 2010–2020

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.     

Effect of the Location of the Detonation Initiation Point and the Position of the Air–Fuel Cloud on Explosion‐Field Parameters

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.     

Can the addition of a dielectric improve the figure of merit of a tunable material?

The influence of addition of a low-loss linear dielectric material to a tunable ferroelectric material has been investigated in terms of the electrostatic consideration. The calculations of the dielectric loss and dielectric non-linearity of ferroelectric-dielectric composites have been performed by using three different models. On the basis of results obtained, the figure of merit of the composite material has been evaluated. No improvement of the figure of merit of composite material compared to the pure ferroelectric has been observed for the considered models.     

Mechanism of the Initial Stage of Thermal Decomposition of Nitroguanidine

A theoretical and experimental study of the thermal decomposition of nitroguanidine(NQ) has been carried out. Various thermolysis channels were studied by quantum chemistry methods at the CCSD(or DLPNO-CCSD) level using the aug-cc-pVDZ basis set. It is shown that the lowest activation enthalpies(170—180kJ/mol) are characteristic of the reactions of NO₂ abstraction from the initial NQ and the reaction channel with the transfer of oxygen from the nitro group to carbon in the limiting st...     

Effect of the Fuel Type on the Characteristics of Air‐Breathing Engines

Experimental studies of airbreathing engines operating on gaseous and liquid fuels are analyzed. It is shown that, for flight conditions with a Mach number 5 at the ground level, the results on operation and thrust–economic characteristics, which were obtained for hydrogenpowered engines, may be used directly in development of the ducts of hypersonic airbreathing engines operating on liquid organoborn fuels.     

Role of the Initial Formation of the Iron Nano-Particles in the Multi-Walled Carbon Nanotubes Growth Process

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.     

Note of the estimation of the Θ temperature and Ψ parameter from the critical temperature data

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.     

Crystallization from the amorphous form of the nanoporous ? form of syndiotactic polystyrene

The recently discovered channel-shaped nanoporous ? crystalline form of syndiotactic polystyrene (s-PS) is generally obtained by a chloroform-induced recrystallization of samples exhibiting the helical γ crystalline form, followed by chloroform desorption in suitable conditions. This nanoporous ? crystalline form can be also obtained by crystallization of amorphous samples as induced by the same chloroform sorption-desorption procedure. This procedure, which does not affect β form samples, when applied to samples exhibiting the trans-planar α form instead leads to a recrystallization into the cavity-shaped nanoporous δ form. Both nanoporous crystalline forms (δ and ?) are obtained, by this chloroform treatment on uniaxially stretched amorphous films. In particular, polarized FTIR microscopy clearly shows that δ and ? crystalline forms prevail in central and lateral film regions, respectively. In fact, in the film central regions, higher polymer draw ratios are reached that lead to higher degrees of trans-planar crystallinity, whose chloroform-induced crystallization leads to δ form formation.