Crystallographic report: Bis[3‐(tri‐p‐tolyl)germyl‐3‐(o‐tolyl)‐propionato]dibutyltin(IV)

The crystal structure of [(p‐CH₃C₆H₄)₃GeCH(o‐CH₃C₆H₄)CH₂CO₂]₂Sn(C₄H₉)₂ consists of a monomer with the atoms of tin and germanium both occupying tetrahedral geometries. However, the tin atom is distorted towards a skew trapezoidal bipyramid geometry as a result of weakly chelating carboxylate ligands. Copyright © 2003 John Wiley & Sons, Ltd.     

One-pot access to a privileged library of six membered nitrogenous heterocycles through multi-component cascade approach

The presence of heterocycles and heteroaromatics as ubiquitous components in a diverse variety of synthetic drugs, biologically active molecules, and natural products has inspired the researchers to develop new strategies and technologies for their easy accessibility. Among them, six membered nitrogenous heterocycles gained immense interest, and significant efforts have been made to the development of synthetic strategies which could lead to the discovery of architecturally complex and diverse molecules with high efficiency, low cost, less organic waste and shorter reaction time. Access to such systems by one-pot multi-component approach with inherent advantages of step-economy, operational simplicity, synthetic efficiency, and environmental compatibility is particularly attractive. The current review article highlights the recent developments in the synthesis of six membered nitrogen-containing heterocyclic scaffolds through one-pot multi-component assembly approach.     

High-Speed Cylindrical Collapse of Type-I Matter

In this paper, the cylindrical symmetric gravitational collapse with anisotropic pressure has been investigated using high-speed approximation scheme. The collapsing speed of the fluid is assumed to be very large. To see the effects of pressure, we have used the equations $ \sqrt{p_{R}/\rho}=k$ and $\sqrt{p_{T}/\rho}=w$ of states for radial pressure and tangential pressure, respectively. It is observed that if the ratios of both pressures, that is, tangential and radial pressures, to energy density are bounded from below by some positive value, there arise two possibilities depending on whether 1?+?k ²???2 w ²?>?0 or 1?+?k ²???2w ²?<?0. For 1?+?k ²???2 w ²?>?0, the high-speed approximation scheme fails, while for 1?+?k ²???2 w ²?<?0, the high-speed approximation works. For vanishing w and k, the high-speed scheme does not break down, and, as a result, a naked singularity forms in this case. For p _T ?=?p _R ?=?p, all the results reduce to the perfect fluid case obtained by Nakao and Morisawa (Prog Theor Phys 113:73, 2005).     

Study on the Role of Metal Oxides in Desulphurization of Some Petroleum Fractions

Metal oxides are highly reactive towards the compounds of sulphur, particularly thioles. A comparative study was made of the desulphurization potential of various metal oxides such as MnO₂, PbO₂, ArO₃, Al₂O₃, MgO₂, ZnO₂ and silica on reaction with Jhal Magsi crude oil and its distillate fractions, i.e., kerosene and diesel oil. The effect of time was also studied and the desulphurization was performed for time durations of one hour, three hours and six hours. The analysis of the residual fractions indicated that significant sulphur depletion occurred with lead oxide and manganese dioxide in the one‐hour and three‐hour reaction times in all three samples. Lead oxide (PbO₂) brought about a maximum desulphurization of 60.28% in the case of crude oil, 54.54% in the case of diesel oil and 52.57% in the case of kerosene oil in a 01 h reaction time. Similarly, manganese oxide (MnO₂) caused a maximum desulphurization of 58.55% in the case of crude oil, 49.38% in the case of diesel oil and 53.30% in case of kerosene oil in a 3 h reaction time. The rest of the metal oxides also exhibited good sulphur removal activity, but their performance is not as noteworthy as in the cases of PbO₂ and MnO₂.     

Effect of working fluid on the performance of a miniature heat pipe system for cooling desktop processor

The heat transfer performance of a miniature heat pipe system (MHPS) used for cooling a desktop computer processor is presented in this paper. The MHPS consists of 6 parallel cylindrical miniature heat pipes (MHPs) which are connected to a copper block at the evaporator section and which are provided with 15 parallel perpendicular copper sheets at the condenser section, used as external cooling fins. Acetone and ethanol are used as working fluids. As heat source a processor is employed which is attached to the copper block. Heat transfer characteristics of the individual MHPs and the complete MHPS using the two working fluids are experimentally determined. The results show that the maximum and steady state temperature of the processor has been significantly reduced by using MHPs with acetone, more than with ethanol, instead of a conventional finned aluminum heat sink with cooling fan. Additional use of a fan results in a much lower processor temperature for both working fluids.