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81.
Cruz-Castañeda J. Aguilar-Ovando E. Buhse T. Ramos-Bernal S. Meléndez-López A. Camargo-Raya C. Fuentes-Carreón C. Negrón-Mendoza A. 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(2):1135-1141
Studies in chemical evolution are intended to demonstrate how compounds of biological importance are generated from substances that could have been found in abiotic conditions on the primitive Earth or in extraterrestrial environments. In this context, the aim of the present work was to examine the behavior of dl-glyceraldehyde in both aqueous solution and solid samples under gamma irradiation. We irradiated dl-glyceraldehyde at different doses and temperatures with a gamma source; even at low doses and temperature (77 K), free radicals were detected. Among the products formed were ethylene glycol and glycolaldehyde. Some sugar-like compounds were also detected.
相似文献82.
M. V. Vishnetskaya A. V. Vasin V. N. Solkan G. M. Zhidomirov M. Ya. Mel’nikov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(11):1905-1907
The interaction of molecular oxygen with aqueous trifluoroacetic acid (TFA) led to an increase in pH. This effect was explained
by a decrease in the concentration of the protonated CF3CO2H2+ and H3O+ species after oxygen was fed in the reactor. Quantum-chemical calculations show that a radical pair can be formed in an activation-free
exothermal reaction involving the radical residue of the acid, the CF3CO2H2+...3O2...CF3CO2− peroxide radical, and the acid molecule in the CF3C2·...HOO· collision complex. It was assumed that the activation of molecular oxygen in aqueous TFA solutions, providing the activity
of the system in oxidations of various organic and inorganic substrates, is related to the formation of peroxide radicals
in them. 相似文献
83.
M. A. Sinel’nikova E. N. Shved V. V. Usachev N. M. Oleinik 《Theoretical and Experimental Chemistry》2010,46(3):168-175
A model was constructed for the mechanism of the reaction of aliphatic and aromatic carboxylic acids with epichlorohydrin
catalyzed by tertiary amines. A mechanism for the catalysis of the transfer of the anion of the nucleophilic reagent by an
ion pair was proposed taking account of the kinetic data and selected chemical and mathematical models. 相似文献
84.
A. B. Mel’nikov E. A. Antonov A. Z. Khrustalev I. M. Zorin A. Yu. Bilibin 《Colloid Journal》2010,72(4):512-516
Polymerized and nonpolymerized micelles of N-acryloyl-11-aminoundecanoic acid and its sodium salt in water and dimethylformamide are studied by viscometry, isothermal
diffusion, and dynamic light scattering. It is revealed that the hydrodynamic sizes of polymerized micelles (PMs) obtained
via polymerization of the surfactants in aqueous solutions at low concentrations of the latter are significantly larger than
those of the starting surfactant micelles. In dimethylformamide, as the surfactant concentration at which the synthesis is
carried out is increased, the hydrodynamic size of PMs, which is calculated in terms of the cylindrical particle model, rises
from 25 to 220 nm. The formation of additional internal crosslinks reduces the equilibrium rigidity of the PM chains by a
factor of 1.5–2. 相似文献
85.
V. T. Lebedev D. N. Orlova V. M. Lebedev Gy. Török A. B. Mel’nikov L. V. Vinogradova 《Russian Journal of Applied Chemistry》2010,83(5):864-868
Association of short-chain sulfopolystyrene ionomers containing 5.2 mol % ionic SO3Li groups in carbon tetrachloride was studied by cold neutron scattering. 相似文献
86.
Semchikov Yu. D. Zhil’tsova O. E. Zaitsev S. D. Mel’nikova N. B. 《Russian Journal of Applied Chemistry》2010,83(7):1284-1288
The colloidal-chemical properties of alternating copolymers of N-vinylpyrrolidone with 1,1,1,3,3,3-hexafluoroisopropyl α-fluoroacrylate were studied by the method of Langmuir film balance. 相似文献
87.
We consider the competitive facility location problem in which two competing sides (the Leader and the Follower) open in succession
their facilities, and each consumer chooses one of the open facilities basing on its own preferences. The problem amounts
to choosing the Leader’s facility locations so that to obtain maximal profit taking into account the subsequent facility location
by the Follower who also aims to obtain maximal profit. We state the problem as a two-level integer programming problem. A
method is proposed for calculating an upper bound for the maximal profit of the Leader. The corresponding algorithm amounts
to constructing the classical maximum facility location problem and finding an optimal solution to it. Simultaneously with
calculating an upper bound we construct an initial approximate solution to the competitive facility location problem. We propose
some local search algorithms for improving the initial approximate solutions. We include the results of some simulations with
the proposed algorithms, which enable us to estimate the precision of the resulting approximate solutions and give a comparative
estimate for the quality of the algorithms under consideration for constructing the approximate solutions to the problem. 相似文献
88.
Detailed calculations of eigenmodes of waveguiding structures made of silver and glass and containing coaxial cables with
a nanoscale cross section of different configurations are conducted. In particular, the study focuses on optical coaxial waveguides
with the core made in the form of a thin metallic cylinder filled with a dielectric. We show that these waveguides support
relatively low-loss propagation of radiation that is strongly localized in the central region, has phase velocity approaching
the speed of light and predominant electric-field orientation (dipole type). Optical characteristics of such waveguides are
compared with those of coaxial-type waveguides containing a continuous central filament made of metal and with a multilayer
structure. Using numeric modeling, we established that the proposed type of the waveguide enables the transmission of an optical
image with relatively low losses with a submicron resolution over a distance considerably longer than its cross section. A
typical propagation length in the waveguides based on silver and glass with the refractive index of about 1.5 at a wavelength
of 500 nm is about 1700 nm. 相似文献
89.
Mel’nik N. N. Zavaritskaya T. N. Kucherenko I. V. Wojtowicz T. Janik E. Plyashechnik O. S. 《Physics of the Solid State》2011,53(8):1722-1726
The spectra of resonant light scattering by ZnTe quantum wires have been measured at excitation energies of 2.18–2.72 eV.
The quantum wires have been grown on Si(100) and GaAs(100) substrates by molecular beam epitaxy. The effect of outgoing resonance
with the electron transition energy E
0 on the intensity of phonon lines of the Stokes spectrum and on the intensity ratio of the Stokes and anti-Stokes spectral
lines has been studied. The energy E
0 has been determined in ZnTe and ZnMgTe quantum wires from the edge luminescence spectra. 相似文献
90.
A. G. Gamzatov A. B. Batdalov A. R. Kaul’ O. V. Mel’nikov 《Physics of the Solid State》2011,53(1):182-188
The correlation between electrical, magnetic, and lattice properties of manganites has been studied by analyzing the temperature
dependence of the electrical resistivity of the La0.85Ag0.15MnO3 manganite. The results have been discussed within the model of a phase-separated manganite in terms of the percolation theory.
It has been shown that, from analyzing the temperature and magnetic field dependences of the electrical resistivity, it is
possible to predict the behavior of the magnetization and specific heat, as well as the change of magnetic entropy near the
phase transition temperature, and that the obtained agreement with experimental data for this analysis is quite reasonable. 相似文献