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91.
We consider reflection of electromagnetic waves from layered structures with various dielectric and magnetic properties, including metamaterials. Assuming periodic variations in the permittivity, we find that the reflection is in general anomalous. In particular, we note that the specular reflection vanishes and that the incident energy is totally reflected in the backward direction, when the conditions for resonant excitation of leaking surface waves are fulfilled. 相似文献
92.
R.K. Shukla Atul Kumar Alok Shukla Kirti Srivastava 《Journal of Molecular Liquids》2008,140(1-3):117-122
Density, ultrasonic velocity, surface tension, excess volume and viscosity of quaternary non-electrolyte solution n-pentane+tolune+n-heptane+cyclohexane has been experimentally determined at 25 °C over a wide range of composition. Assuming a quaternary fluid solution to be made of six binaries, a statistical approach of Prigogine–Flory–Patterson (PFP) theory has been extended to develop the expressions for dynamic viscosity, surface tension excess volume and ultrasonic velocity of quaternary fluid system. A reasonable agreement has been achieved between theory and experiment. An attempt has also bee made to explain the nature of molecular interactions involved in the light of excess thermodynamic functions whose sign and magnitude depend upon the chain length and size of the component fluids and also studied the role of order breakers (toluene and cyclohexane) on these properties. 相似文献
93.
Kinetic and thermodynamic investigations were performed for a mixed aqueous-organic, 1:1 (v/v) water–1,4-dioxane medium, which was found to be an efficient solvent for the interaction of a neutral dichlorotris(triphenylphosphine) ruthenium(II), RuCl2(PPh3)3 complex with carbon monoxide at atmospheric pressure. During the interaction, RuCl2(PPh3)3 dissociates to a neutral complex dichlorobis(triphenylphosphine) ruthenium(II), RuCl2(PPh3)2, by losing a coordinated PPh3 ligand and RuCl2(PPh3)2 coordinates with CO to form an in situ carbonyl complex RuCl2(CO)(PPh3)2. The in situ formed carbonyl complex RuCl2(CO)(PPh3)2 was thoroughly characterized by equilibrium, spectrophotometric, IR, and electrochemical techniques. Under equilibrium conditions, the rate and dissociation constants for the dissociation of PPh3 from RuCl2(PPh3)3 were found to be favorable for the formation of the carbonyl complex RuCl2(CO)(PPh3)2. The rates of complexation for the formation of RuCl2(CO)(PPh3)2 were found to follow an overall second-order kinetics being first order in terms of the concentrations of both carbon monoxide and RuCl2(PPh3)2. The determined activation parameters corresponding to the rate constant (ΔH# = 35.9 ± 2.5 kJ mol−1 and ΔS# = −122 ± 6 J K−1 mol−1) and thermodynamic parameters corresponding to the formation constant (ΔH° = −33.5 ± 4.5 kJ mol−1, ΔS° = −25 ± 8 J K−1 mol−1, and ΔG° = −25.7 ± 2.0 kJ mol−1) were found to be highly favorable for the formation of the complex RuCl2(CO)(PPh3)2. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 359–369, 2008 相似文献
94.
It is shown that zonal magnetic fields (ZMFs) can be nonlinearly excited by incoherent drift waves (DWs) in a current carrying nonuniform magnetoplasma. The dynamics of incoherent DWs in the presence of ZMFs is governed by a wave-kinetic equation. The governing equation for ZMFs in the presence of nonlinear advection force of the DWs is obtained from the parallel component of the electron momentum equation and the Faraday law. Standard techniques are used to derive a nonlinear dispersion relation, which depicts instability via which ZMFs are excited in plasmas. ZMFs may inhibit the turbulent cross-field particle and energy transport in a nonuniform magnetoplasma. 相似文献
95.
96.
97.
Neelesh Bharti Shukla 《Polymer Degradation and Stability》2009,94(8):1238-1244
The oxidative degradation of poly(acrylic acid) (PAA), a water soluble polymer, was studied at various temperatures with different concentrations of persulfates, potassium persulfate (KPS), ammonium persulfate (APS) and sodium persulfate (SPS). The photodegradation of PAA was also examined with APS as oxidizer. The degraded samples were analyzed for the time evolution of molecular weight distribution by gel permeation chromatography. A theoretical model based on the continuous distribution kinetics was developed that accounted for the polymer degradation and the dissociation of persulfate. The rate coefficients for the oxidative and photooxidative degradation of PAA were determined from the parametric fit of the model with experimental data. The rate of degradation increased with increasing amount of persulfate in both oxidative and photooxidative degradation. The rate of degradation also increased with increasing temperature in the case of oxidative degradation. 相似文献
98.
Naresh Kumar Sandeep Kumar Shukla Poonam Tandon Vishwambhar Dayal Gupta 《Journal of Polymer Science.Polymer Physics》2009,47(23):2353-2367
Poly(p‐phenylene sulfide) (PPS) is an important polymer of engineering interest particularly useful in the electronics and automotive industries. Normal mode analysis including phonon dispersion has been performed to understand completely the vibrational spectra of this polymer. Various characteristic features of the dispersion curves have been reported. Crossing/Repulsion between various pairs of modes at certain phase values have been explained as arising due to internal symmetry in the energy momentum space. The heat capacity is calculated as a function of temperature via density‐of‐states in the range 220–360 K. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2353–2367, 2009 相似文献
99.
100.
Idris Mohd Srivastava Seema Baggi Tulsidas R. Shukla Sudhir Kumar 《平面色谱法杂志一现代薄层色谱法》2010,23(5):339-342
JPC – Journal of Planar Chromatography – Modern TLC - A simple, accurate, and inexpensive high-performance thin-layer chromatography (HPTLC) method has been established for analysis of... 相似文献