52 research outputs found
First principle computation of stripes in cuprates
We present a first principle computation of vertical stripes in
within the LDA+U method. We find that Cu centered
stripes are unstable toward O centered stripes. The metallic core of the stripe
is quite wide and shows reduced magnetic moments with suppressed
antiferromagnetic (AF) interactions. The system can be pictured as alternating
metallic and AF two-leg ladders the latter with strong AF interaction and a
large spin gap. The Fermi surface shows warping due to interstripe
hybridization. The periodicity and amplitude of the warping is in good
agreement with angle resolved photoemission experiment. We discuss the
connection with low-energy theories of the cuprates.Comment: 5 pages,4 figure
Data on granulometric composition of calcium phosphate obtained by dispersion method
The kinetics of calcium phosphate crystallization from model solutions of saliva and liquid phase of dental plaque has been studied by the dispersion method. It was found that the composition of the saliva model system is favorable for the growth of larger crystals. The size of the particles in crystallization varies nonlinearly. As supersaturation grows, the amount of formed particles increases, however, the average rate of crystallite growth decreases
Features of radiation damage of Ni-Ti alloy under exposure to heavy ions of gaseous elements
The consistent patterns of changes in structural and phase state, hardening and temperature ranges of martensitic transformations in Ni-Ti alloy with the shape memory effect after implantation of heavy ions 16O3+, 40Ar8+ and 84Kr15+ under comparable parameters have been experimentally studied. It is found that under the impact of 84Kr15+ ions, a two-layer surface structure with radiation-hardened second layer is formed, radiation-stimulated phase transformation B19'>B2 occurs in the near-surface layer and out-range area, and the martensitic transformation temperature increases toward higher values after implantation of 40Ar8+ and 84Kr15+ ions
Effect of ion irradiation on tribological properties of composite coatings
The paper discusses the results of the research in the effect of ion irradiation on tribological properties of multiphase ion-plasma coatings. It is shown that all the investigated coatings behave differently under ion irradiation: the Zn-Al, Fe-Al, Zn-Cu-Al coating is radiation-resistant and the friction coefficient does not virtually change; the Cr-Mn-Si-Cu-Fe- Al coating exhibits twofold increase in the friction coefficient, and that for Mn-Fe-Cu-Al coating decreases threefold. These changes are related to changes which occur in the coating surface under ion bombardment
Crystal-field splitting for low symmetry systems in ab initio calculations
In the framework of the LDA+U approximation we propose the direct way of
calculation of crystal-field excitation energy and apply it to La and Y
titanates. The method developed can be useful for comparison with the results
of spectroscopic measurements because it takes into account fast relaxations of
electronic system. For titanates these relaxation processes reduce the value of
crystal-field splitting by as compared with the difference of LDA one
electron energies. However, the crystal-field excitation energy in these
systems is still large enough to make an orbital liquid formation rather
unlikely and experimentally observed isotropic magnetism remains unexplained.Comment: 13 pages, 5 figures, 3 table
Data on granulometric composition of calcium phosphate obtained by dispersion method
The kinetics of calcium phosphate crystallization from model solutions of saliva and liquid phase of dental plaque has been studied by the dispersion method. It was found that the composition of the saliva model system is favorable for the growth of larger crystals. The size of the particles in crystallization varies nonlinearly. As supersaturation grows, the amount of formed particles increases, however, the average rate of crystallite growth decreases
Hidden faces of Duringβs herpetiform dermatitis: a rare clinical case with an atypical location of a rash on the penis
The purpose of the study to present a clinical case of Duringβs herpetiform dermatitis with an atypical location of the rash on the penis.Π¦Π΅Π»Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ β ΠΏΡΠ΅Π΄ΡΡΠ°Π²ΠΈΡΡ ΠΊΠ»ΠΈΠ½ΠΈΡΠ΅ΡΠΊΠΈΠΉ ΡΠ»ΡΡΠ°ΠΉ Π³Π΅ΡΠΏΠ΅ΡΠΈΡΠΎΡΠΌΠ½ΠΎΠ³ΠΎ Π΄Π΅ΡΠΌΠ°ΡΠΈΡΠ° ΠΡΡΠΈΠ½Π³Π° Ρ Π°ΡΠΈΠΏΠΈΡΠ½ΡΠΌ ΡΠ°ΡΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΠ΅ΠΌ ΡΡΠΏΠΈ Π½Π° ΠΏΠΎΠ»ΠΎΠ²ΠΎΠΌ ΡΠ»Π΅Π½Π΅
Determination of the orbital moment and crystal field splitting in LaTiO
Utilizing a sum-rule in a spin-resolved photoelectron spectroscopic
experiment with circularly polarized light, we show that the orbital moment in
LaTiO is strongly reduced both below and above the N\'{e}el temperature.
Using Ti x-ray absorption spectroscopy as a local probe, we found
that the crystal field splitting in the subshell is about 0.12-0.30
eV. This large splitting does not facilitate the formation of an orbital
liquid
Study of thermal effects of silicate-containing hydroxyapatites
The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 Β°Π‘ that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state
Crystal-field Splitting for Low Symmetry Systems in ab Initio Calculations
In the framework of the LDA+U approximation we propose the direct way of calculation of crystal-field excitation energy and apply it to La and Y titanates. The method developed can be useful for comparison with the results of spectroscopic measurements because it takes into account fast relaxations of electronic system. For titanates these relaxation processes reduce the value of crystal-field splitting by βΌ30% as compared with the difference of LDA one electron energies. However, the crystal-field excitation energy in these systems is still large enough to make an orbital liquid formation rather unlikely and experimentally observed isotropic magnetism remains unexplained. Β© 2005 The American Physical Society.We would like to thank I.V. Solovyev, D.E. Kondakov, M.A. Korotin, A.I. Poteryaev, S. Okatov, and A.I. Lichtenstein for very useful discussion of calculation details. We also acknowledge fruitful communications with G. Khaliullin, M. Haverkort, M. GrΓΌninger, M. Cwik, E. MΓΌller-Hartmann, M. Braden, and especially L.H. Tjeng. This work is supported by the Russian Foundation for Basic Research under Grant Nos. RFFI-04-02-16096 and RFFI-03-0239024, the Dynasty Foundation and International Center for Fundamental Physics in Moscow program for young scientists, Russian Science Support Foundation program for best Ph.D. students of Russian Academy of Sciences, Netherlands Organization for Scientific Research through NWO 047.016.005 and by the Deutsche Forschungsgemeinschaft through SFB 608
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