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1.
T.V. Torchynska A.L. Quintos Vazquez G. Polupan Y. Matsumoto L. Khomenkova L. Shcherbyna 《Journal of Non》2008,354(19-25):2186-2189
This paper presents the results of PL spectrum study for Si nano-clusters in amorphous silicon matrix. The hydrogenated amorphous Si layers were prepared by the hot-wire CVD method on glass substrates. The layers were deposited at different wafer temperatures 280, 360, 420 and 460 °C and at one filament temperature of 1650 °C. The joint analysis of PL and X-ray diffraction spectra in dependence on the technological conditions and on different sizes of Si nano-clusters has been done. The mechanisms of PL are discussed as well. 相似文献
2.
R.L. Mascorro Alquicira J.L. Casas Espinola E. Velázquez Lozada G. Polupan L. Shcherbyna 《Superlattices and Microstructures》2012
The photoluminescence (PL), its temperature dependence and X ray diffraction (XRD) have been studied in the symmetric In0.15Ga0.85As/GaAs quantum wells (QWs) with embedded InAs quantum dots (QDs), obtained with the variation of QD growth temperatures (470–535 °C). The increase of QD growth temperatures is accompanied by the enlargement of QD lateral sizes (from 12 up to 28 nm) and by the shift non monotonously of PL peak positions. The fitting procedure has been applied for the analysis of the temperature dependence of PL peaks. The obtained fitting parameters testify that in studied QD structures the process of In/Ga interdiffusion between QDs and capping/buffer layers takes place partially. However this process cannot explain the difference in PL peak positions. 相似文献
3.
The problem of optimization of the honeycomb wall structure of pipes subjected to static loads is investigated. As the basic
engineering design parameter of the pipes, their ring rigidity is assumed. The corresponding optimization problem is formulated.
Starting from the necessary ring rigidity of cylindrical pipes made of polymeric materials with honeycomb walls, their geometrical,
physicomechanical, and technological parameters are determined. Based on the calculations, the optimum geometry (wall thickness,
diameter, and the number of layers) of the pipes is found. Numerical results are presented and analyzed.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 6, pp. 853–860, November–December, 2008. 相似文献
4.
G Fuchs K-H Müller J Freudenberger K Nenkov S-L Drechsler SV Shulga D Lipp A Gladun T Cichorek P Gegenwart 《Pramana》2002,58(5-6):791-797
The effect of substitutional disorder on the superconducting properties of YNi2B2C was studied by partially replacing yttrium and nickel by Lu and Pt, respectively. For the two series of (Y, Lu)Ni2B2C and Y(Ni, Pt)2B2C compounds, the upper critical field H
c2(T) and the specific heat c
p(T, H) in the superconducting mixed state have been investigated. Disorder is found to reduce several relevant quantities such
as T
c, the upper critical field H
c2(0) at T=0 and a characteristic positive curvature of H
c2(T) observed for these compounds near T
c. The H
c2(T) data point to the clean limit for (Y, Lu) substitutions and to a transition to the quasi-dirty limit for (Ni, Pt) substitutions.
The electronic specific heat contribution γ(H) exhibits significant deviations from the usual linear γ(H) law. These deviations reduce with growing substitutional disorder but remain even in the quasidirty limit which is reached
in the Y(Ni1−x
, Pt
x
)2B2C samples for x=0.1. 相似文献
5.
O. V. Maksymuk N. M. Shcherbyna R. M. Makhnitskii N. V. Ganulich 《Journal of Mathematical Sciences》2010,165(3):333-341
A problem of determination of the stress-strain state, stability and optimization of the honeycomb structure of a polymeric
tube wall under the action of a static force load is considered. As is customary in engineering practice, the ring rigidity
of the tube is taken as its main design quantity. The corresponding problem of optimization is formulated. From the condition
of provision of the required value of the ring rigidity of a honeycomb polymeric cylindrical shell, we determine the geometric,
physicomechanical, and technological parameters. On the basis of the performed calculations, a justification of an optimal
geometry (the thickness of the wall, the diameter of a winding tubule, and the number of layers of the tube structure) is
presented. Numerical results and their analysis are presented. 相似文献
6.
Based on the generalized Timoshenko-type shell theory, a numerical-analytical procedure for determining contact stresses from
the interaction between a cylindrical composite shell and rigid bandings is proposed. Specific cases of loading and contact
interaction (ideal contact through an adhesive interlayer) are considered. The contact problems are reduced to the solution
of a Fredholm integral equation of the second-kind. A calculation analysis is performed.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 1, pp. 109–120, January–February, 2000. 相似文献
7.
The photoluminescence (PL) inhomogeneity has been studied in InAs quantum dots (QDs) embedded in the symmetric In0.15Ga0.85As/GaAs quantum wells (QWs) with QDs grown at different temperatures. It was shown that three reasons are responsible for the emission inhomogeneity in studied QD structures: (i) the high concentration of nonradiative recombination centers in the capping In0.15Ga0.85As layer at low QD growth temperatures, (ii) the QD density and size distributions for the structure with QD grown at 510 °C, (iii) the high concentration of nonradiative recombination centers in the GaAs barrier at higher QD growth temperatures. 相似文献
8.
We solve a problem of determination of the contact rigidity of a structural joint of a steel thin-walled pipe under the action
of internal pressure with a shroud made of a composite material using a special technology. A mathematical model of the contact
interaction of the pipe and shroud modeled by cylindrical shells of different length was constructed using the classical Kirchhoff–Love
theory of shells. We obtain an analytic solution of the contact problem under conditions of ideal contact of the elements
of the structural joint by the conjugation method. A numerical analysis of the influence of geometric and physicomechanical
characteristics of the shroud on the contact pressure and rigidity of the shrouded pipe is presented. 相似文献
9.
Non-resonant microwave absorption (NRMA) studies of superconducting MgB2 and a sample containing ∼10% by weight of MgO in MgB2 are reported. The NRMA results indicate near absence of intergranular weak links in the pure MgB2 sample. A linear temperature dependence of the lower critical field H
c1 is observed indicating a non-s wave superconductivity. However, the phase reversal of the NRMA signal which could suggest d wave symmetry is also not observed. In the MgB2 + MgO sample, much larger low field dependent absorption is observed indicating the presence of intergranular weak links.
The hysteretic behavior of NRMA is compared and contrasted in the two samples. In the pure MgB2 sample, a large hysteresis is observed between the forward and the reverse scans of the magnetic field indicating strong
pinning of flux lines. This hysteresis saturates a few degrees below T
c while in the MgB2 + MgO sample, a much slower increase of hysteresis with decreasing temperature is observed, a signature of weaker pinning. 相似文献
10.
Shcherbyna SV Bohme DK Baranov VI Loboda A Swartz CR Anthony JE 《Journal of the American Society for Mass Spectrometry》2006,17(2):222-229
A high-performance orthogonal time-of flight (TOF) mass spectrometer, in combination with the matrix assisted laser desorption/ionization
(MALDI) source operating at elevated pressure (∼1 torr in N2), was used to perform MALDI-TOF analyses of pentacene and some of its derivatives with and without an added matrix. These
molecules are among the most interesting semiconductor materials for organic thin film transistor applications (OTFT). The
observation of ion-molecule reactions between “cold” analyte ions and neutral analyte molecules in the gas phase has provided
some insight into the mechanism of pentacene cluster formation and its functionalized derivatives. Furthermore, some of the
matrices employed to assist the desorption/ionization process of these compounds were observed to influence the outcome via
ion-molecule reactions of analyte ions and matrix molecules in the gas phase. The stability and reactivity of the compounds
and their clusters in the MALDI plume during gas-phase expansion were evaluated; possible structures of the resulting clusters
are discussed. The MALDI-TOF technique was also helpful in distinguishing between two isomeric forms of bis-[(triisopropylsilyl)-ethynyl]-pentacene. 相似文献