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排序方式: 共有498条查询结果,搜索用时 31 毫秒
81.
Dipankar Kumar Aly R. Seadawy Atish Kumar Joardar 《Chinese Journal of Physics (Taipei)》2018,56(1):75-85
In this study, the modified Kudryashov method is used to construct new exact solutions for some conformable fractional differential equations. By implementing the conformable fractional derivative and compatible fractional complex transforms, the fractional generalized reaction duffing (RD) model equation, the fractional biological population model and the fractional diffusion reaction (DR) equation with quadratic and cubic nonlinearity are discussed. As an outcome, some new exact solutions are formally established. All solutions have been verified back into its corresponding equation with the aid of maple package program. We assure that the employed method is simple and robust for the estimation of the new exact solutions, and practically capable for reducing the size of computational work for solving a various class of fractional differential equations arising in applied mathematics, mathematical physics and biology. 相似文献
82.
R. Karmakar A. Sur M. Kanoria 《Journal of Applied Mechanics and Technical Physics》2016,57(4):652-665
The aim of the present contribution is the determination of the thermoelastic temperatures, stress, displacement, and strain in an infinite isotropic elastic body with a spherical cavity in the context of the mechanism of the two-temperature generalized thermoelasticity theory (2TT). The two-temperature Lord–Shulman (2TLS) model and two-temperature dual-phase-lag (2TDP) model of thermoelasticity are combined into a unified formulation with unified parameters. The medium is assumed to be initially quiescent. The basic equations are written in the form of a vector matrix differential equation in the Laplace transform domain, which is then solved by the state-space approach. The expressions for the conductive temperature and elongation are obtained at small times. The numerical inversion of the transformed solutions is carried out by using the Fourier-series expansion technique. A comparative study is performed for the thermoelastic stresses, conductive temperature, thermodynamic temperature, displacement, and elongation computed by using the Lord–Shulman and dual-phase-lag models. 相似文献
83.
Ghosh Bidisha Roy Shubham Bardhan Souravi Mondal Dhananjoy Saha Ishita Ghosh Saheli Basu Ruma Karmakar Parimal Das Kaustuv Das Sukhen 《Journal of fluorescence》2022,32(4):1489-1500
Journal of Fluorescence - This article reports the fluorometric detection of toxic hexavalent chromium Cr (VI)) in wastewater and Cr (VI) contaminated living cells using in-situ grown carbon... 相似文献
84.
Karmakar S Choudhury M Das AS Maiti A Majumdar S Mitra C 《Natural product research》2012,26(6):500-509
This study examined the efficacy of hydroalcoholic extract of dried clove buds, which is rich in phenolic compounds namely eugenol and eugenol derivatives (precursors of flavones, isoflavones and flavonoids), on different primary and secondary osteoporotic marker changes in an ovariectomised (OVX) rat model of osteoporosis. Female Wistar rats were randomly divided into three groups: sham-operated control (A), OVX (B) and OVX plus 50% hydroalcoholic extract of dried clove buds for 4 weeks (C). Results indicated that, compared to control, serum alkaline phosphatase (AP; 48.25%, p?0.01), serum tartrate-resistant acid phosphatase (TRAP; 63.48%, p?0.01), urinary calcium (14.70%, p?0.01), urinary phosphate (50.30%, p?0.01) and urinary creatinine (122.44%, p?0.01) were significantly altered in OVX rats. All these altered responses were significantly restored (AP: 27.53%, p?0.01; TRAP: 33.51%, p?0.01; calcium: 53.15%, p?0.01; phosphate: 27.49%, p?0.01; creatinine: 46.40%, p?0.01) by supplementation with hydroalcoholic extract of dried clove buds. Results of bone density, bone mineral content, bone tensile strength and histological analysis also showed similar trend of results, which supported initial observations of this study. It is proposed that hydroalcoholic extract of dried clove buds has bone-preserving efficacy against hypogonadal osteoporosis. 相似文献
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86.
Flexural gravity wave scattering by multiple articulated floating elastic plates is investigated in the three cases for water of finite depth, infinite depth and shallow water approximation under the assumptions of two-dimensional linearized theory of water waves. The elastic plates are joined through connectors, which act as articulated joints. In the case when two semi-infinite plates are connected through a single articulation, using the symmetric characteristic of the plate geometry and the expansion formulae for wave-structure interaction problem, the velocity potentials are obtained in closed forms in the case of finite and infinite water depths. On the other hand, in the case of shallow water approximation, the continuity of energy and mass flux are used to obtain a system of equations for the determination of the full velocity potentials for wave scattering by multiple articulations. Further, using the results for single articulation and assuming that the articulated joints are wide apart, the wide-spacing approximation method is used to obtain the reflection coefficient for wave scattering due to multiple articulated floating elastic plates. The effects of the stiffness of the connectors, length of the elastic plates and water depth on the propagation of flexural gravity waves are investigated by analysing the reflection coefficient. 相似文献
87.
The quaternary ammonium salts find extensive use in a variety of chemical applications as surfactants and phase-transfer catalysts. Even though the interaction of the surfactants with various systems has been studied rather extensively, very little information is available on how the phase-transfer catalysts (PTC) interact with the dipolar systems in nonpolar media and how/whether these solubilizing agents affect the properties of the dissolved molecules. In this paper, the interaction of several tetraalkylammonium salts, commonly used as PTC, with a number of electron donor-acceptor (EDA) systems has been studied by absorption and fluorescence spectroscopy. The phase-transfer catalysts have been found to affect both the absorption and fluorescence properties of the EDA systems. The spectral changes of the EDA molecules induced by the tetraalkylammonium salts suggest the formation of an 1:1 complex between the two in nonpolar media. An electrostatic interaction between the phase-transfer catalysts (which exist as ion pairs in nonpolar media) and the dipolar molecules is shown to be the driving force for the formation of the complex. The dependence of the formation constant of the complex on the polarity of the media suggests a charge-transfer nature of the complex. It is shown that the anionic component of the salts serves as a source of electron to the positive end of the dipolar molecule, while the tetraalkylammonium cation, besides helping solubilization of its anionic counterpart in the nonpolar media, serves neutralizing the negative charge at the acceptor end of the EDA molecule. In effect, a cooperative influence of the cationic and anionic components of the PTC enhances the charge separation within the dipolar fluorophores. On the basis of the PTC-induced changes in the photophysical behavior of the EDA molecules, a possible structure for the 1:1 complex has been proposed. It has been concluded that a phase-transfer catalyst should not be treated as an innocuous substance that merely helps transfer of a polar substance from a polar to a nonpolar environment. Instead, it is demonstrated that the association of a PTC with a dipolar species can significantly change various properties of the latter. 相似文献
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90.
D. Khattib M. Ishan Dr. S. Karmakar Dr. H. Kostrhunova Prof. V. Brabec Prof. D. Gibson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(43):9475-9480
The oxidation of cis-[Pt(NH3)2(OAc)2] with H2O2 yields a mixture of two isomers: ctc-[Pt(NH3)2(OH)2(OAc)2] and ctc-[Pt(NH3)2(OH)(OAc)(OH)(OAc)]. Following modification with 4-phenylbutyric (PhB) anhydride, two isomers were separated and characterized; the symmetric ctc-[Pt(NH3)2(PhB)2(OAc)2] ( 1 ) and the nonsymmetric ctc-[Pt(NH3)2(PhB)(OAc)(PhB)(OAc)] ( 2 ). They differ in their log P values and despite having similar cellular uptake and similar DNA platination levels, the symmetric ctc-[Pt(NH3)2(OH)2(OAc)2] is more than 4-fold more potent than the nonsymmetric isomer in a panel of 4 cancer cell lines. 相似文献