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101.
An analysis is made for the steady two-dimensional magneto-hydrodynamic flow of an incompressible viscous and electrically
conducting fluid over a stretching vertical sheet in its own plane. The stretching velocity, the surface temperature and the
transverse magnetic field are assumed to vary in a power-law with the distance from the origin. The transformed boundary layer
equations are solved numerically for some values of the involved parameters, namely the magnetic parameter M, the velocity exponent parameter m, the temperature exponent parameter n and the buoyancy parameter λ, while the Prandtl number Pr is fixed, namely Pr = 1, using a finite difference scheme known as the Keller-box method. Similarity solutions are obtained in the presence of
the buoyancy force if n = 2m−1. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed
and discussed. It is found that both the skin friction coefficient and the local Nusselt number decrease as the magnetic parameter
M increases for fixed λ and m. For m = 0.2 (i.e. n = −0.6), although the sheet and the fluid are at different temperatures, there is no local heat transfer at the surface of
the sheet except at the singular point of the origin (fixed point). 相似文献
102.
Muhammad Faizan Nazar 《Journal of Dispersion Science and Technology》2013,34(5):596-605
Ultraviolet (UV)-visible behavior of 3,4-dihydroxy-9,10-dioxo-2-anthracenesulfonic acid sodium salt (ARS) has been studied at pH 4.0, aqueous medium, and at pH 10.0. The effects of cetyl trimethylammoniumbromide (CTAB) on the UV-visible spectra of ARS have been evaluated qualitatively as well as quantitatively in the different concentration regions of CTAB. The shift in the UV-visible spectrum of ARS, due to CTAB, at its low concentration is comparable to the shift shown by the same at pH 10.0. In acidic and basic pH, effect of CTAB is significantly lowered on the UV-visible spectra than ARS in the purely aqueous medium. In aqueous and basic medium, lower values of partition and binding constant are obtained compared to the one obtained in acidic medium. Conductivity studies show that increasing dye concentrations have no effect on its partitioning behavior nevertheless critical micelle concentration of CTAB is lowered. 相似文献
103.
We report on new luminescence bands exhibited by natural brown/mauve diamonds. We describe detailed absorption and luminescence measurements in the visible spectral region. The structured bands with ZPL at 2.424 eV, 2.114 eV, 1.819 eV and 1.707 eV, and a broad band with a maximum at 1.8 eV are shown to be the main components of the visible luminescence. Bands with ZPL at 2.114 eV, 1.819 eV and 1.707 eV are shown to correspond to forbidden transitions with lifetimes of the order of msec. Energy absorbed by the 2.424 eV centre is transferred into the 1.819 eV centre. 相似文献
104.
Evgeniya D. Novikova Dr. Yuri A. Vorotnikov Dr. Nazar A. Nikolaev Dr. Alphiya R. Tsygankova Dr. Michael A. Shestopalov Dr. Olga A. Efremova 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(8):2818-2825
Photodynamic and photothermal therapies (PDT, and PTT, respectively) are promising candidates for multimodal anticancer therapies (i.e., combinations of therapies), since their action is based on mechanisms that generally cannot be resisted by cancer cells, that is, generation of highly oxidizing oxygen species and high temperature, respectively. Herein, hybrid materials that combine octahedral molybdenum clusters as potential PDT agents and plasmonic spherical gold nanoparticles (AuNPs) as PTT agents are reported. Partial overlap of the photoemission spectrum of the cluster and the surface plasmon resonance band of the AuNPs facilitates energy transfer between the photoactive components, which resulted in synergetic enhancement of their photophysical properties. Specifically, by careful selection of the spacing between the cluster and the gold nanoparticle, a significant increase in luminescence and photosensitizing properties of the cluster was achieved in comparison with similar, but gold-free, particles. On the other hand, the cluster complex facilitated energy conversion to heat by gold particles and hence increased the heating rate under laser irradiation. 相似文献
105.
Halland N Nazaré M Alonso J R'kyek O Lindenschmidt A 《Chemical communications (Cambridge, England)》2011,47(3):1042-1044
A versatile and efficient palladium catalyzed domino reaction leading to a broad range of substituted 1-aminoindoles has been developed. The title compounds were prepared from 2-halo-phenylacetylenes and simple hydrazines in good to excellent yields in just a few hours under mild conditions. 相似文献
106.
Davis LJ Heinmaa I Ellis BL Nazar LF Goward GR 《Physical chemistry chemical physics : PCCP》2011,13(11):5171-5177
Here we report the observation of electron delocalization in nano-dimension xLiFePO(4):(1 - x)FePO(4) (x = 0.5) using high temperature, static, (31)P solid state NMR. The (31)P paramagnetic shift in this material shows extreme sensitivity to the oxidation state of the Fe center. At room temperature two distinct (31)P resonances arising from FePO(4) and LiFePO(4) are observed at 5800 ppm and 3800 ppm, respectively. At temperatures near 400 °C these resonances coalesce into a single narrowed peak centered around 3200 ppm caused by the averaging of the electronic environments at the phosphate centers, resulting from the delocalization of the electrons among the iron centers. (7)Li MAS NMR spectra of nanometre sized xLiFePO(4):(1 - x)FePO(4) (x = 0.5) particles at ambient temperature reveal evidence of Li residing at the phase interface between the LiFePO(4) and FePO(4) domains. Moreover, a new broad resonance is resolved at 65 ppm, and is attributed to Li adjacent to the anti-site Fe defect. This information is considered in light of the (7)Li MAS spectrum of LiMnPO(4), which despite being iso-structural with LiFePO(4) yields a remarkably different (7)Li MAS spectrum due to the different electronic states of the paramagnetic centers. For LiMnPO(4) the higher (7)Li MAS paramagnetic shift (65 ppm) and narrowed isotropic resonance (FWHM ≈ 500 Hz) is attributed to an additional unpaired electron in the t(2g) orbital as compared to LiFePO(4) which has δ(iso) = -11 ppm and a FWHM = 9500 Hz. Only the delithiated phase FePO(4) is iso-electronic and iso-structural with LiMnPO(4). This similarity is readily observed in the (7)Li MAS spectrum of xLiFePO(4):(1 - x)FePO(4) (x = 0.5) where Li sitting near Fe in the 3+ oxidation state takes on spectral features reminiscent of LiMnPO(4). Overall, these spectral features allow for better understanding of the chemical and electrochemical (de)lithiation mechanisms of LiFePO(4) and the Li-environments generated upon cycling. 相似文献
107.
He G Herbst JF Ramesh TN Pinkerton FE Meyer MS Nazar L 《Physical chemistry chemical physics : PCCP》2011,13(19):8889-8893
The hydrogen storage properties of Li(7)VN(4) and Li(7)MnN(4) were investigated both by experiment and by density functional theory calculations. Li(7)VN(4) did not sorb hydrogen under our experimental conditions. Li(7)MnN(4) was observed to sorb 7 hydrogen atoms through the formation of LiH, Mn(4)N, and ammonia gas. An applied pressurized mixture of H(2)/Ar and H(2)/N(2) gases was helpful to mitigate the release of NH(3) but could not prevent its formation. The introduction of N(2) also caused weight gain of the sample by re-nitriding the absorbed products LiH and Mn(4)N, which correlated with the presence of Li(2)NH, LiNH(2), and Mn(2)N detected by X-ray diffraction. While our observed results for Li(7)VN(4) and Li(7)MnN(4) differ in detail, they are in overall qualitative agreement with our theoretical work, which strongly suggests that both compounds are unlikely to form quaternary hydrides. 相似文献
108.
Fadzilah Md. Ali Roslinda Nazar Norihan Md. Arifin Ioan Pop 《Heat and Mass Transfer》2011,47(2):155-162
In this paper, the problem of steady magnetohydrodynamic boundary layer flow and heat transfer of a viscous and electrically
conducting fluid over a stretching sheet is studied. The effect of the induced magnetic field is taken into account. The transformed
ordinary differential equations are solved numerically using the finite-difference scheme known as the Keller-box method.
Numerical results are obtained for various values of the magnetic parameter, the reciprocal magnetic Prandtl number and the
Prandtl number. The effects of these parameters on the flow and heat transfer characteristics are determined and discussed
in detail. When the magnetic field is absent, the closed analytical results for the skin friction are compared with the exact
numerical results. Also the numerical results for the heat flux from the stretching surface are compared with the results
reported by other authors when the magnetic field is absent. It is found that very good agreement exists. 相似文献
109.
S. K. Godunov Yu. D. Manuzina M. A. Nazar’eva 《Computational Mathematics and Mathematical Physics》2011,51(1):88-95
Convergence of the approximate solution of fluid dynamics problems obtained using Godunov’s scheme to the discontinuous solution
is investigated. 相似文献
110.
Hassan Abrar Ul Sumrra Sajjad Hussain Zafar Muhammad Nadeem Nazar Muhammad Faizan Mughal Ehsan Ullah Zafar Muhammad Naveed Iqbal Mazhar 《Molecular diversity》2022,26(1):51-72
Molecular Diversity - During the present investigation, two new sulfonamide-based Schiff base ligands, 4-{[(2-hydroxy-3-methoxyphenyl)methylidene]amino}-N-(1,3-thiazol-2-yl)benzene-1-sulfonamide... 相似文献