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11.
Alexey M. Starosotnikov Maxim A. Bastrakov Sergey Yu. Pechenkin Margarita A. Leontieva Vadim V. Kachala Svyatoslav A. Shevelev 《Journal of heterocyclic chemistry》2011,48(4):824-828
The 1,3‐dipolar cycloaddition of unstabilized N‐methyl azomethine ylide to mononitro benzazoles was studied. Depending on the nature of substituents and annelated azoles, the reaction affords previously unknown isoindole fused heterocyclic systems. The reactivity of the cycloadducts was examined. J. Heterocyclic Chem., (2011). 相似文献
12.
Algorithms for detecting optimal hereditary structures in graphs, with application to clique relaxations 总被引:1,自引:0,他引:1
Svyatoslav Trukhanov Chitra Balasubramaniam Balabhaskar Balasundaram Sergiy Butenko 《Computational Optimization and Applications》2013,56(1):113-130
Given a simple undirected graph, the problem of finding a maximum subset of vertices satisfying a nontrivial, interesting property Π that is hereditary on induced subgraphs, is known to be NP-hard. Many well-known graph properties meet the above conditions, making the problem widely applicable. This paper proposes a general purpose exact algorithmic framework to solve this problem and investigates key algorithm design and implementation issues that are helpful in tailoring the general framework for specific graph properties. The performance of the algorithms so derived for the maximum s-plex and the maximum s-defective clique problems, which arise in network-based data mining applications, is assessed through a computational study. 相似文献
13.
S. V. Trukhanov I. O. Troyanchuk D. D. Khalyavin I. M. Fita H. Szymczak K. Bärner 《Journal of Experimental and Theoretical Physics》2002,94(2):329-335
Investigations are performed of the crystal structure and magnetic and electromagnetic properties of single crystals (0.23 ≤x≤0.34) and polycrystals (0 ≤x ≤0.50) of an Nd1?x BaxMnO3?δ system of solid solutions. It is found that, for samples prepared in the air, the maximal Curie temperature (T C ) does not exceed 150 K, while, in the case of polycrystalline samples in the concentration range of 0.34 ≤x ≤0.50, prepared in a reducing medium (a gaseous mixture of argon and carbon monoxide), T C increases to 320 K. As a result of the reducing medium effect on the compositions, the type of the magnetic phase transition to the paramagnetic state changes from the first to second order. The electrical resistivity of reduced polycrystalline samples (0.34≤x ≤0.50) decreases in magnitude and correlates with the behavior of magnetization. Both series of samples, prepared both in the air and in a reducing medium, exhibit a transition from the metal to dielectric state at a temperature below T C . The temperature and field dependences of magnetization for the stoichiometric polycrystalline com-position of Nd0.50Ba0.50MnO3 are measured under conditions of hydrostatic pressure. It is demonstrated that the hydrostatic pressure induces in Nd0.50Ba0.50MnO3 the transition from the antiferromagnetic to ferromagnetic state. Based on the measurement results, hypothetical magnetic phase diagrams are constructed for the system of solid solutions being treated, depending on the concentration of barium and the method of preparation. It is found that no T TC increase is observed in single crystals (0.23≤x≤0.34) such as is observed in polycrystals. It is assumed that the abrupt increase in T C of polycrystalline samples prepared in a reducing medium is a result of the emergence of extended defects and microstresses in the crystal lattice. 相似文献
14.
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16.
S. F. Marenkin V. M. Trukhan I. V. Fedorchenko S. V. Trukhanov T. V. Shoukavaya 《Russian Journal of Inorganic Chemistry》2014,59(4):355-359
A new ferromagnetic material based on a Cd3As2 + MnAs composite with the Curie point of 320 K has been prepared. Magnetic and electrical properties of the composite have been found to be determined by manganese arsenide nanoclusters. The composite has metallic conduction. Its resistance decreases with increasing magnetic field both at low and room temperatures, indicating spin-dependent scattering mechanisms and exchange interactions between magnetic nanoclusters in the composite. 相似文献
17.
18.
S. V. Trukhanov A. V. Trukhanov A. N. Vasiliev H. Szymczak 《Journal of Experimental and Theoretical Physics》2010,111(2):209-214
The magnetic and thermal properties of the anion-deficient La0.70Sr0.30MnO2.85 manganite are investigated in wide temperature (4–350 K) range, including under hydrostatic pressure (0–1.1 GPa). Throughout
the pressure range investigated, the sample is spin glass with diffused phase transition into paramagnetic state. It is established,
that spin glass state is a consequence of exchange interaction frustration of the ferromagnetic clusters embeded into antiferromagnetic
clusters. The magnetic moment freezing temperature T
f
of ferromagnetic clusters increases under pressure, freezing temperature dependence on pressure is characterized by derivative
value ∼4.5 K/GPa, while the magnetic ordering T
MO temperature dependence is characterized by derivative value ∼13 K/GPa. The volume fraction of sample having ferromagnetic
state is V
fer ∼ 13% and it increases under a pressure of 1.1 GPa by ΔV
fer ≈ 6%. Intensification of ferromagnetic properties of the anion-deficient La0.70Sr0.30MnO2.85 manganite under hydrostatic pressure is a consequence of oxygen vacancies redistribution and unit cell parameters decrease.
The most likely mechanism of frustrated exchange interactions formation is discussed. 相似文献
19.
The crystal structure and magnetic properties of the (La0.3Sr0.7)0.5Ca0.5FeO3 solid solution with a perovskite structure have been investigated. The solid solution has been synthesized according to the
high-pressure technique. The unit cell parameters have been refined using the Rietveld full-profile analysis under the assumption
of the single-phase crystalline state and the two-phase model corresponding to the parent compositions. It follows from the
calculations that the best agreement between the experimental data and the theoretical curve is observed for the two-phase
model. The measurement of the magnetic properties also indicates the coexistence of two magnetic phases. 相似文献
20.
S. V. Trukhanov I. O. Troyanchuk A. V. Trukhanov I. A. Bobrikov V. G. Simkin A. M. Balagurov 《JETP Letters》2006,84(5):254-257
The crystal structure of anion-deficient La0.70Sr0.30MnO3?δ manganites (δ = 0, 0.10, 0.15, and 0.20) has been studied by powder neutron diffraction at room temperature. The crystal structures of the stoichiometric La0.70Sr0.30MnO3 and anion-deficient La0.70Sr0.30MnO2.90 samples are satisfactorily described by the rhombohedral R $\bar 3$ c space group. The anion-deficient La0.70Sr0.30MnO2.85 sample separates into two perovskite phases with the R $\bar 3$ c and I4/mcm space groups. The crystal structure of La0.70Sr0.30MnO2.80 cannot be described by a single perovskite phase in the I4/mcm space group. It is found that the clustering of oxygen vacancies is the cause of structural phase separation at 293 K in anion-deficient La0.70Sr0.30MnO3?δ manganites. 相似文献