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101.

Publications dedicated to cyclic oligoesters based on cyclic butylene terephthalate were analyzed and summarized. The features of their preparation and structure and their properties were considered with a special focus on advantages and disadvantages of the methods of their preparation: polycondensation at high dilution and depolymerization. The prospects of application of cyclic butylene terephthalate for polymer nanocomposite production were demonstrated. A development strategy for this research area was suggested.

  相似文献   
102.
The hydrochemical precipitation method at 298 and 333 K with, respectively, thiocarbamide and sodium selenosulfate was used to obtain nanostructured powders of copper sulfide with formula composition Cu2S, which are composed of globules 200–500 nm in diameter, formed by 70–100-nm particles, and copper(I) selenide, composed of crystallites with polyhedral shape, sizes of 80 to 500 nm, and a formula composition Cu1.84Se. An X-ray diffraction analysis revealed the orthorhombic Cu2S structure (space group no. 39-Abm2) with unit cell parameters a = 1.182 nm, b = 2.705 nm, and c = 1.343 nm. Powders of Cu1.84Se copper selenide have a cubic structure (space group Fm3m) with lattice constant a = 0.5693 nm. A thermal analysis demonstrated that the chemically precipitated Cu2S and Cu1.84Se powders have a stable elemental composition up to 200–240°C. An intense oxidation of the samples begins at a temperature exceeding 250°C and is accompanied by a sharp decrease in their content of sulfur (selenium) and by an increase in the content of oxygen.  相似文献   
103.
Alkylation of N,N-dialkylcarboxamides with 1,3-dehydroadamantane has been accomplished for the first time. The reaction involves the C–H bond in the α-position with respect to the carbonyl group and provides a convenient one-step preparation of substituted carboxylic acid amides containing an 1-adamantyl substituent and a pharmacophoric group in the amide moiety.  相似文献   
104.
Immobilization of polyethylene glycol-substituted 1-methylimidazolium bromide on the surface of magnetic Fe3O4 nanoparticles through hexane-1,6-diyldicarbamate linker afforded a powerful and reusable heterogeneous phase-transfer catalysis which was successfully used for regioselective ring opening of epoxides with azide and nitrite anions in aqueous medium. The new catalyst can readily be recovered by simple magnetic decantation and recycled several times without appreciable loss of catalytic activity.  相似文献   
105.
The effect of microwave pre-treatment (MwP) on anaerobic digestion of sewage sludge was studied by means of thermal analysis and evolved gas analysis. The effect of the pre-treatment at low energy input (<1000 kJ L?1) on sludge solubilisation was studied with the aid of response surface methodology. The pre-treatment process was subsequently studied at energies of 488–2700 kJ L?1 to evaluate the improvement in biogas production under mesophilic conditions. Organic matter modifications were studied using a Setaram TGA92 analyser at atmospheric pressure coupled to an MSC200 quadrupole mass spectrometer from Balzers. Particle size analysis was carried out using a Laser Diffraction Particle Size Analyser LS 13 320 Beckmann Coulter for evaluating the effect of MwP on sludge particles. Results showed an increase in organic matter solubilisation with the increase in the energy applied. Modifications in the specific surface area of the organic matter due to the MwP resulted in increments in methane yields. However, an accumulation of complex compounds was observed in thermal profiles at the maximum energy input (2700 kJ L?1). Semi-continuous digestion experiments were evaluated using as substrate pre-treated sludge at the optimum energy value (975 kJ L?1). Results showed a significant increase in methane yield (43 %) when evaluating the process at hydraulic retention times (HRTs) of 25–10 days.  相似文献   
106.
In the production of commercial Li-ion batteries, the active materials slurries are generally prepared using polyvinylidene fluoride (PVdF) as binder because of its good adhesion properties and electrochemical stability. Unfortunately, there are some disadvantages related to the use of PVdF: the most important is the use of toxic and environmentally unfriendly solvents, such as N-methyl-pyrrolidone (NMP), and the second is the high costs. In the light of these considerations, it seemed straightforward to investigate the suitability of some water-soluble, inexpensive, and eco-friendly materials to test as alternative binders (sodium alginate, chitosan tragacanth gum, gelatin). The rheological properties of these materials have been investigated in addition to the electrochemical characterization. Furthermore, graphite electrodes with PVdF, carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) binders have been considered for sake of comparison. We found that some of these water-soluble binders, besides good electrochemical performances, showed a high adhesion to the current collector and a good electrochemical stability under the experimental conditions employed, which makes them interesting for the next generation of Li-ion batteries.  相似文献   
107.
The influence of various stabilizers on the properties of rubber based on silicone rubber SKTV is studied. It is established that the use of the Ca/Zn stabilizer in the resin composition makes it possible to increase thermal resistance and physico-mechanical characteristics of the rubber used to make sealing elements in the automotive industry.  相似文献   
108.
We discuss a perturbation theory on the light front regularized by a method analogous to Pauli–Villars regularization for the (2+1)-dimensional SU(N)-symmetric gauge theory. This allows constructing a correct renormalized light-front Hamiltonian.  相似文献   
109.
We show the unimprovability of a theorem on sufficient convergence conditions for the trigonometric Fourier series of a function in classes ?(L) in the case when the class ?(L) is “close” to L.  相似文献   
110.
For a constrained pseudoinverse problem whose operators satisfy the complementarity condition we propose a one-parameter continuous regularization method of the second order. This method is based on stabilization of solutions to Cauchy problems for a linear differential equation of the second order in a Hilbert space which is obtained from the heavy ball method. We establish requirements to the parametric regularization function and perturbation levels that ensure the stability of the method in the class of all possible bounded perturbations.  相似文献   
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