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181.
Recent released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. This hints a cosmological privileged axis in our anisotropic expanding universe. This paper proceeds a modified redshift in anisotropic cosmological model as \( 1+\tilde{z}(t,\hat{\mathbf{p }})=\frac{a(t_{0)}}{a(t)}(1-A(\hat{\mathbf{n }}.\hat{\mathbf{p }}))\) (where A is the magnitude of anisotropy, \(\hat{\mathbf{n }}\) is the direction of privileged axis, and \(\hat{\mathbf{p }}\) is the direction of each SNe Ia sample to galactic coordinates) along with anisotropic parameter \(\delta =\frac{A(\hat{\mathbf{n }}.\hat{\mathbf{p }})}{1+A(\hat{\mathbf{n }}.\hat{\mathbf{p }})}\). The luminosity distance is expanded with model-independent cosmographic parameters as a function of modified redshift \(\tilde{z}\). As the transformation matrix \(M(n\times n)\) is obtained to convert the Taylor series coefficients of isotropic luminosity distance to corresponding anisotropic parameters. These results culminate the magnitude of anisotropy about \(\mid A\mid \simeq 10^{-3}\) and the direction of preferred axis as \((l,b)=\left( 297^{-34}_{+34},3^{-28}_{+28}\right) \), which are consistent with other studies in \(1-\sigma \) confidence level. 相似文献
182.
A tailoring proposal for design of the strained quantum well structures, optimized with respect to the intersubband resonant second-order nonlinear properties, is presented in this article. A genetic-algorithm-based method is used in order to obtain the optimal potential shape, doping concentration and location in strained GaN-AlGaN-AlN quantum wells, and the structures are analyzed by a numerical solution of the Schrödinger-Poisson self-consistent method. In general form two types of asymmetric structures with remarkable results are obtained with different resonant frequencies, and in both cases results show a considerably high enhancement in the magnitude of the second-order nonlinear susceptibilities in higher resonant frequencies in comparison with a single quantum well structure with the same well width (5.02×10−8 m/V at to 2.9×10−5 m/V at and 2.43×10−5 m/V at ). The optimized structures exhibit considerable absorption coefficient and electroabsorption properties due to high dipole transition matrix element, high dopant concentration and reasonable Fermi level. 相似文献
183.
Akpan N. Ikot H. Hassanabadi E. Maghsoodi Saber Zarrinkamar N. Salehi 《Physics of Particles and Nuclei Letters》2014,11(4):443-457
In this paper, we calculate the energy spectra and the corresponding wavefunction for the symmetric and asymmetric trigonometric Rosen-Morse potential of the Dirac equation within the framework of spin and pseudospin symmetry limits including the tensor interaction using the supersymmetric quantum mechanics (SUSYQM) formalism. We have also reported some numerical results and figures to show the effect of tensor interaction. 相似文献
184.
Peyman Najafi Moghaddam Mahsa Ensafi Avval Amir Reza Fareghi 《Colloid and polymer science》2014,292(1):77-84
Cellulose-based biodegradable polymers—as microspheres or hydrogels—are suitable for drug delivery systems. In this work, cellulose microfibers were converted to cellulose esters for subsequent graft copolymerization either by free radical or atom transfer radical polymerization (ATRP). For the former, carboxymethyl cellulose (CMC) was prepared and then modified through grafting of poly(hydroxyethyl acrylate) or polyacrylamide. ATRP was achieved by chloroacetylation of cellulose followed by graft copolymerization of hydroxyethyl acrylate or acrylamide monomers. The degree of substitution for CMC and chloroacetylated cellulose (CAC) was determined by the method described in US Pharmacopeia NF24 and by titration method, respectively. CMC, CAC, and the grafted copolymers were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, X-ray diffraction, and atomic force microscopy; the latter technique clearly shows the chain growth of the synthetic polymers on the backbone surface. Furthermore, cephalexin antibiotic was loaded on the copolymers, and the resultant in vitro drug release studied in three different media (buffer solutions with pH equal to 3, 6.1, and 8). 相似文献
185.
Maliheh Safaiee Mohammad Ali Zolfigol Mahsa Tavasoli Mohammad Mokhlesi 《Journal of the Iranian Chemical Society》2014,11(6):1593-1597
A simple method for the oxidative aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridines is described using hydrogen peroxide as green oxidant and silica vanadic acid as catalyst in acetonitrile at room temperature. The catalyst can be easily recovered and reused for 15 reaction cycles without considerable loss of activity. 相似文献
186.
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188.
Baghban Alireza Pourfayaz Fathollah Ahmadi Mohammad Hossein Kasaeian Alibakhsh Pourkiaei Seyed Mohsen Lorenzini Giulio 《Journal of Thermal Analysis and Calorimetry》2018,131(2):1213-1220
Journal of Thermal Analysis and Calorimetry - The effect of Na2CO3 additive on the steam gasification characteristics of Sunjiahao (SJH) coal char was studied in the present paper. Na2CO3-catalyzed... 相似文献
189.
We have used the results of renormalization of a two-dimensional quantum stress-tensor to develop a conformally invariant dynamical model. The model requires the consideration of those conformal frames in which there exists a correspondence between the trace anomaly and a cosmological constant. We apply this model to a two-dimensional Schwarzschild (-de Sitter) spacetime to show that in these conformal frames one may achieve Hawking radiation without recourse to the trace anomaly. 相似文献
190.
Minoo Dabiri Peyman Salehi Mostafa Baghbanzadeh Mahboobeh Bahramnejad 《Monatshefte für Chemie / Chemical Monthly》2007,138(12):1253-1255
Summary. Alum (KAl(SO4)2 · 12H2O) catalyzed the efficient synthesis of mono- and disubstituted 1,3,4-oxadiazoles by the condensation of acyl hydrazides with
orthoesters under solvent-free conditions at 100°C. This methodology offers significant improvements for the synthesis of
oxadiazoles with regard to the yield of products, simplicity in operation, inexpensive reagents, and green aspects by avoiding
toxic catalysts and solvents. 相似文献