Quantum corrections to the entropy of Einstein–Maxwell dilaton–axion black holes

We study corrections to the entropy of Einstein–Maxwell dilaton–axion black holes beyond semiclassical approximations. We consider the entropy of the black hole as a state variable and derive these corrections using the exactness criteria of the first law of thermodynamics. We note that from this general frame-work the entropy corrections for “simpler” black holes like Schwarzschild, Reissner–Nordström and anti-de Sitter–Schwarzschild black holes follow easily. This procedure gives us the modified area law as well.     

Synthesis of 5-aryl-1,3-dimethyl-6-(alkyl- or aryl-amino) furo [2,3-d]pyrimidine derivatives by reaction between isocyanides and pyridinecarbaldehydes in the presence of 1,3-dimethylbarbituric acid

5-Aryl-6-(alkyl- or aryl-amino)-1,3-dimethylfuro [2,3-d]pyrimidine derivatives were obtained by in situ reaction alkyl or aryl isocyanides and pyridinecarbaldehyde derivatives in the presence of 1,3-dimethylbarbituric acid in dichloromethane without any prior activation or modifications.     

Wave-function-based characteristics of hybrid mesons

We propose some extensions of the quark potential model to hybrids, fit them to the lattice data and use them for the purpose of calculating the masses, root mean square radii and wave functions at the origin of the conventional and hybrid charmonium mesons. We treat the ground and excited gluonic field between a quark and an antiquark as in the Born-Oppenheimer expansion, and use the shooting method to numerically solve the required Schrödinger equation for the radial wave functions; from these wave functions we calculate the mesonic properties. For masses we also check through a Crank Nichelson discretization. For hybrid charmonium mesons, we consider the exotic quantum number states with J ^PC = 0^+?, 1^?+ and 2^+?. We also compare our results with the experimentally observed masses and theoretically predicted results of the other models. Our results have implications for scalar form factors, energy shifts, magnetic polarizabilities, decay constants, decay widths and differential cross-sections of conventional and hybrid mesons.     

Defect induced ferromagnetism in carbon-doped ZnO thin films

We report on room temperature ferromagnetism in C-doped ZnO thin films prepared by electron beam evaporation. Magnetization, Hall effect, X-ray photoemission spectroscopy (XPS) and X-ray diffraction studies have been conducted to investigate the source and nature of ferromagnetism in C-doped ZnO. The samples were observed to have n-type conduction with the carrier concentration increasing with C doping. XPS does not give any evidence for C substituted at the O site, and is more consistent with the formation of C-O bonds and with the presence of C primarily in the +4 state. It is suggested that the ferromagnetism originates in the development of Zn vacancies that are stabilized due to the incorporation of C in a high valence state (C⁴⁺).     

Role of condenser iris in optical tweezer detection system

Optical tweezers have proven to be very useful in various scientific fields, from biology to nanotechnology. In this Letter we show, both by theory and experiment, that the interference intensity pattern at the back focal plane of the condenser consists of two distinguishable areas with anticorrelated intensity changes when the bead is moved in the axial direction. We show that the space angle defining the border of two areas linearly depends on the NA of the objective. We also propose a new octant photodiode, which could significantly improve the axial resolution compared to the commonly used quadrant photodiode technique.     

Some curvature properties of Cartan spaces with mth root metrics

In this paper, we define some non-Riemannian curvature properties for Cartan spaces. We consider a Cartan space with the mth root metric. We prove that every mth root Cartan space of isotropic Landsberg curvature, or isotropic mean Landsberg curvature, or isotropic mean Berwald curvature reduces to a Landsberg, weakly Landsberg, and weakly Berwald spaces, respectively. Then we show that the mth root Cartan space of almost vanishing H-curvature satisfies H?=?0.     

Numerical solutions of peristaltic flow of Williamson fluid with radially varying MHD in an endoscope

In this article we have studied the peristaltic motion of an incompressible Williamson fluid with constant and radially varying magnetohydrodynamics (MHD) in an endoscope. Using the low Reynolds and long wavelength assumptions, the equations of Williamson fluid model in simplified form are solved using (i) the HAM method and (ii) the Shooting method. The comparisons of both solutions have been found a very good agreement. Graphical results have been presented for various emerging parameters. © British Crown Copyright 2010/MOD. Reproduced with permission. Published by John Wiley & Sons, Ltd.     

Synthesis of 2-arylbenzimidazoles catalyzed by transition metal nitrates

A simple and practical procedure for synthesis of 2-arylbenzimidazoles by a one-pot condensation of o-phenylenediamine with aromatic aldehydes in the presence of a catalytic amount of M(NO₃)₂·6H₂O (M = Mn, Fe, Co, Ni, Cu) in ethanol at room temperature is described. Major advantages of this practical procedure are use of a readily available catalyst, high yields, short reaction times, and simplicity of the reaction and workup.     

A mathematical model to characterise effects of liquid hold-up on bosh silicon transport in the dripping zone of a blast furnace

A first principle based mathematical model has been developed to characterise the effect of total liquid hold-up on the bosh silicon distribution behaviour in the dripping zone of a blast furnace. Two specific cases of hold-up behaviour have been investigated, namely, hold-up in the absence and in the presence of counter current gas flow conditions. The model exemplifies coupled phenomenon of chemical kinetics, transport processes and liquid hold-up to characterise the silicon behaviour in the dripping zone. The present modelling investigation shows that the bosh silicon level diminishes with the enhanced liquid hold-up in the dripping zone. Further, the influence of counter current gas flow on the hold-up is not significant. However, it has been observed that the liquid phase temperature reduces with increased liquid hold-up in dripping zone under steady state operating conditions. The model predictions of bosh silicon distribution have been validated with the published literatures (bulk values) and found to be in good agreement.     

Treated Rice Bran for Scavenging Cr(III) and Hg(II) from Acidic Solution

The purpose of this study was to examine the efficiency with which rice bran (treated or untreated) removes heavy metals, especially Cr(III) and Hg(II), from acidic solution. Sorption assays were done in shaken flasks in the presence of rice bran. Different experimental conditions such as pH, volume of solution, bran weight, particle size, exchange time and stirring time were improved. The efficiency of bran was studied before and after treatments. For treatment, solutions of acid, alkali and salt were used. The results show that after treating with 4 M sodium chloride solution, its efficiency in removal of Cr(III) and Hg(II) was improved. Kinetic measurements of chromium and mercury removal by bran have revealed that sorption equilibrium was obtained after 10 min of contact. Sorption experiments done with various granulometric fractions of rice bran have shown that this sorbent has the same efficiencies in meshes higher than 20. Further research is necessary in order to determine a mechanism for cations removal by the bran. It is mentioned that the process of making polished rice from brown rice discharges rice bran; therefore, it is very inexpensive, with a cost of 1/50 ? 1/40 of that of synthetic sorbent, and thus its use would significantly lower the cost of wastewater treatment.