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131.
E. Kasapoglu H. Sari I. Sokmen 《Physica E: Low-dimensional Systems and Nanostructures》2003,19(4):332-335
We have studied theoretically the impurity binding energy for wires of different shapes (V-shaped quantum wire (V-QWR) and rectangular wire) with a variational procedure without using any coordinate transformation. The effective potential for V-QWR used in this work consists of a square well potential in the z-direction and full graded well potential in the x-direction. Our results are in good agreement with previous theoretical results, found by the coordinate transformation method. Furthermore, it is shown that the impurity binding energy in quantum wires is sensitive to the geometrical effects. 相似文献
132.
Muge Sari Yilmaz Ilayda Acaroglu Degitz Sabriye Piskin 《Journal of Thermal Analysis and Calorimetry》2017,130(2):727-734
The aim of the current study is to obtain the thermal behavior and kinetic analyses of the removal of surfactant from MCM-41 synthesized from tailings slurry at different heating rates. X-ray diffraction and thermogravimetric analyses were carried out to determine the characterization of the synthesized samples. Kissinger–Akahira–Sunose and Friedman isoconversional kinetic methods were applied for the purpose of determining the kinetic analysis parameters of the decomposition of surfactant from the mesoporous molecular sieves MCM-41 under non-isothermal conditions. For the comparison of these results, MCM-41 was synthesized from a pure silica source. The thermal behaviors of MCM-41 synthesized from tailings slurry do not differ from samples synthesized from pure silica during the decomposition reactions. The kinetic analysis’ results indicate that the decomposition reactions of the synthesized MCM-41 samples had complex reaction mechanisms. 相似文献
133.
Laminar forced convection of gaseous slip flow in a circular micro-channel filled with porous media under local thermal equilibrium
condition is studied numerically using the finite difference technique. Hydrodynamically fully developed flow is considered
and the Darcy–Brinkman–Forchheimer model is used to model the flow inside the porous domain. The present study reports the
effect of several operating parameters (Knudsen number (Kn), Darcy number (Da), Forchhiemer number (Γ), and modified Reynolds number ) on the velocity slip and temperature jump at the wall. Results are given in terms of the velocity distribution, temperature
distribution, skin friction , and the Nusselt number (Nu). It is found that the skin friction is increased by (1) decreasing Knudsen number, (2) increasing Darcy number, and (3)
decreasing Forchheimer number. Heat transfer is found to (1) decrease as the Knudsen number, or Forchheimer number increase,
(2) increase as the Peclet number or Darcy number increase. 相似文献
134.
Ozkan Sari Leda Bassit Christina Gavegnano Tamara R. McBrayer Louise McCormick Bryan Cox Steven J. Coats Franck Amblard Raymond F. Schinazi 《Tetrahedron letters》2017,58(7):642-644
Herein, we report the synthesis of novel 2′,2′,3′,3′-tetrafluorinated nucleoside analogs along with their phosphoramidate prodrugs. A tetrafluoro ribose moiety was coupled with different Boc/benzoyl-protected nucleobases under Mitsunobu conditions. After deprotection, tetrafluorinated nucleosides 13b, 14b, 20b-22b were reacted with phenyl-(isopropoxy-l-alaninyl)-phosphorochloridate to afford corresponding monophosphate prodrugs 24b–28b. All synthesized compounds were evaluated against several DNA and RNA viruses including HIV, HBV, HCV, Ebola and Zika viruses. 相似文献
135.
136.
Journal of Nanoparticle Research - In recent years, nickel nanoparticles (Ni NPs) have attracted a growing attention from the scientific research community, because they are inexpensive,... 相似文献
137.
Jahede Tekeykhah Seyed Mohsen Hosseini Gholamali Jalali Jalil Alavi Abbas Esmaili Sari 《声与振动》2019,53(6):263-276
Sound pollution is one of the most important urban problems which
endangers mental and physical health of the residents. This study was aimed to
assess the influence of different tree species, including Fraxinus rotundifolia,
Robinia pseudoacacia, Platanus orientalis, Platycladus orientalis, and Pinus
eldarica, in reducing noise pollution in the Abidar Forest Park. A further objective was to identify the contaminated areas of Sanandaj city and to propose suitable noise absorbent tree species in consistent conditions. For each tree stands
the noise measurements were performed during intervals at frequencies of 250,
500 and 1000 Hz, besides an open area with the same topography. With regards
to the second purpose, a total of 50 stations with residential, commercial, residentialcommercial, and green space applications were selected across the city. Equivalent
Continuous Sound Pressure Level (Leq) was determined in five replicates for 30
min. The measurements were performed under stable weather conditions and low
wind velocity at 17:00 (traffic peak) in summer and fall. All of the Leq values were
above the threshold noise level. The highest noise reduction was recorded in summer
(i.e., green season); Platanus and Platycladus species demonstrated the highest and
lowest noise absorption (31.43 dB and 22.28 dB, respectively). Furthermore, a
meaningful difference was observed between Leq values of commercial, residential,
commercial-residential, and green space urban applications, and the central parts of
the city showed noticeable noise pollution. Taken together, due to being exposed to
higher than the acceptable threshold noise level, the residents of Sanandaj will be
endangered to health problems in the near future; thus consideration should be given
to the noise pollution sources. 相似文献
138.
Using the effective mass and parabolic band approximations and a variational procedure we have calculated the combined effects of intense laser radiation, hydrostatic pressure, and applied electric field on shallow-donor impurity confined in cylindrical-shaped single and double GaAs-Ga1−xAlxAs QD. Several impurity positions and inputs of the heterostructure dimensions, hydrostatic pressure, and applied electric field have been considered. The laser effects have been introduced by a perturbative scheme in which the Coulomb and the barrier potentials are modified to obtain dressed potentials. Our findings suggest that (1) for on-center impurities in single QD the binding energy is a decreasing function of the dressing parameter and for small dot dimensions of the structures (lengths and radius) the binding energy is more sensitive to the dressing parameter, (2) the binding energy is an increasing/decreasing function of the hydrostatic pressure/applied electric field, (3) the effects of the intense laser field and applied electric field on the binding energy are dominant over the hydrostatic pressure effects, (4) in vertically coupled QD the binding energy for donor impurity located in the barrier region is smaller than for impurities in the well regions and can be strongly modified by the laser radiation, and finally (5) in asymmetrical double QD heterostructures the binding energy as a function of the impurity positions follows a similar behavior to the observed for the amplitude of probability of the noncorrelated electron wave function. 相似文献
139.
Fourier transform technique in variational treatment of two-electron parabolic quantum dot
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In this work,we propose an efficient method of reducing the computational effort of variational calculation with a Hylleraas-like trial wavefunction.The method consists of introducing integral transforms for the terms as r k 12 exp (λr 12) which provide the calculation of the expectation value of energy and the relevant matrix elements to be done analytically over single-electron coordinates instead of Hylleraas coordinates.We have used this method to calculate the ground state energy of a two-electron system in a spherical dot and a disk-like quantum dot separately.Under parabolic confinement potential and within effective mass approximation size and shape effects of quantum dots on the ground state energy of two electrons have been investigated.The calculation shows that our results even with a small number of basis states are in good agreement with previous theoretical results. 相似文献
140.
Tewfik Sari 《Comptes Rendus Mathematique》2010,348(13-14):747-751
In this Note, we give a global asymptotic stability result for the competition mathematical model between several species in a chemostat, by using a new Lyapunov function. The model includes both monotone and non-monotone response functions, distinct removal rates for the species and variable yields, depending on the concentration of substrate. We obtain, as corollaries of our result, three global stability theorems which were considered in the literature. 相似文献