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41.
The problem of preparation of a block copolymer of precise molecular-weight distribution (MWD) and with heterogeneous composition on the basis of gel-permeation chromatography (GPC) data has been investigated. It has been shown that in MWD calculations the distribution f(p) of the composition p in individual GPC fractions should be taken into account. The type of the f(p) functions can be simultaneously established by an independent method, such as use of adsorption-column or thin-layer chromatography sensitive to the composition of the copolymer. It has also been shown that the actual f(p) may be replaced by a corresponding piecewise distribution, of simple form, without decrease in the precision of calculation of the MWD and average molecular weights of most known block copolymers. 相似文献
42.
D. V. Nesterov A. V. Mekhayev O. V. Koryakova A. V. Pestov V. A. Bakulev 《Russian Journal of Applied Chemistry》2017,90(7):1154-1158
Synthesis in a gel as a method for the preparation of poly(chlorosulfostyrene) by treating polystyrene with chlorosulfonic acid was proposed, which makes it possible to obtain a polymer with a total degree of functionalization of sulfo and chlorosulfo groups up to 1.0. The possibility of regulating the degree of chlorosulfonation in the range from 50 to 100% was shown. The composition and structure of the products of polymer-analogous transformations were characterized by elemental analysis, FTIR spectroscopy, and thermogravimetry with IR identification of the decomposition products. Chlorosulfonation in the gel makes it possible to achieve a high degree of functionalization even at lower temperatures, at room temperature, and at less time than compared with known methods. 相似文献
43.
44.
G. A. Domrachev V. K. Khamylov B. A. Nesterov V. T. Bychkov I. V. Lomakova 《Russian Chemical Bulletin》1977,26(12):2594-2595
Conclusions The decomposition of tetracarbonyl(triethylgermyl) cobalt in a flow vacuum system at 150° gives the high-temperature-modification of cobalt, while CoGe and CoGe2 are formed at 400°.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2804–2806, December, 1977. 相似文献
45.
Consideration is given to the effect of thermal expansion of crystal lattice upon the partial contributions to the magnetic hyperfine field for non-magnetic atoms in metallic ferromagnets. The existence of correlation between the temperature anomalies of a hyperfine field and the thermal expansion of the crystal lattice is shown in a simple and illustrative way. 相似文献
46.
A. M. Gromov K. N. Nesterov S. A. Pirkovskii G. V. Solodukhov V. M. Trusova 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(11):1566-1570
The results from investigating the effect of radiation exposure on the rate of chemical reactions in acid aqueous solutions
of Fe2+, which are widely used in hydrometallurgy of nonferrous metals to extract the target components into solution from ores,
are presented. The potential of the applied method is demonstrated. 相似文献
47.
A. A. Shalimov A. M. Nesterenko L. I. Nesterov A. Yu. Petin A. D. Sinitsa 《Russian Journal of General Chemistry》2009,79(10):2108-2112
Reactions of N-acetyltrifluoroacetamide with chlorophosphites give rise to O-phosphorylated N-trifluoroacetoacetylimidates, which transform into α-phosphorylated vinylamides of trifluroacetic acid as a result of vinylphosphite-vinylphosphonate
rearrangement. On the basis of nonempirical calculations data the reaction protocol of N-acetyltrifluoroacetamide with chlorophosphites was suggested. 相似文献
48.
Abstract. We consider the Riemannian geometry defined on a convex set by the Hessian of a self-concordant barrier function, and its
associated geodesic curves. These provide guidance for the construction of efficient interior-point methods for optimizing
a linear function over the intersection of the set with an affine manifold. We show that algorithms that follow the primal—dual
central path are in some sense close to optimal. The same is true for methods that follow the shifted primal—dual central
path among certain infeasible-interior-point methods. We also compute the geodesics in several simple sets. 相似文献
49.
In this paper, we study the Riemannian length of the primal central path in a convex set computed with respect to the local
metric defined by a self-concordant function. Despite some negative examples, in many important situations, the length of
this path is quite close to the length of a geodesic curve. We show that in the case of a bounded convex set endowed with
a ν-self-concordant barrier, the length of the central path is within a factor O(ν
1/4) of the length of the shortest geodesic curve.
This paper presents research results of the Belgian Program on Interuniversity Poles of Attraction initiated by the Belgian
State, Prime Minister’s Office, Science Policy Programming. 相似文献
50.
V. V. Zelentsov V. P. Kremnev A. A. Nesterov V. V. Porodenko A. A. Shishkov 《Fluid Dynamics》1984,19(6):977-982
In asymmetric blowing of a gas into the supersonic part of a nozzle the main flow is perturbed by the jet which is being blown. Two interaction regimes are distinguished. In the first the perturbation of the main flow does not extend to the side of the nozzle opposite to the blast: the central angle subtended by the perturbation of the exit section of the nozzle is 2a < 180 ° (Fig. 1). This regime is characterized by the fact that the curvature of the nozzle has no effect on the magnitude of the lateral force. In the second regime the zone of the perturbed flow extends to the side of the nozzle opposite to the blast (2a > 180 °), and this leads to a decrease in the gradient of the lateral force with respect to the flow rate of the gas which is being blown. The first regime has been studied in the most detail.Translated fron Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6. pp. 136–141, November–December, 1984. 相似文献