Activation of O2 Across a C(sp3)-C(sp3) Bond

The activation of atmospheric molecular dioxygen (O2) is reported which occurred across a C(sp3)-C(sp3) bond of a piperazine derivative without any catalyst at ambient condition under the formation of 1,2,4,7-dioxadiazoctane,...

Stable and Efficient Red Perovskite Light-Emitting Diodes Based on Ca2+-Doped CsPbI3 Nanocrystals

α-CsPbI3 nanocrystals (NCs) with poor stability prevent their wide applications in optoelectronic fields. Ca2+ (1.00 Å) as a new B-site doping ion can successfully boost CsPbI3 NC performance with both improved phase stability and optoelectronic properties. With a Ca2+/Pb2+ ratio of 0.40%, both phase and photoluminescence (PL) stability could be greatly enhanced. Facilitated by increased tolerance factor, the cubic phase of its solid film could be maintained after 58 days in ambient condition or 4 h accelerated aging process at 120°C. The PL stability of its solution could be preserved to 83% after 147 days in ambient condition. Even using UV light to accelerate aging, the T50 of PL could boost 1.8-folds as compared to CsPbI3 NCs. Because Ca2+ doping can dramatically decrease defect densities of films and reduce hole injection barriers, the red light-emitting diodes (LEDs) exhibited about triple enhancement for maximum the external quantum efficiency (EQE) up to 7.8% and 2.2 times enhancement for half-lifetime of LED up to 85 min. We believe it is promising to further explore high-quality CsPbI3 NC LEDs via a Ca2+-doping strategy.

Effect of elevated CO2 and temperature on growth and yield of wheat grown in sub-humid climate of eastern Indo-Gangetic Plain (IGP)

The atmospheric CO2 will be in the range of 510 to 760 L-1 by the end of 21st century and mean global temperature will be 1.5 to 4.5 oC higher than the present day which has a direct and indirect effect on agriculture. India is a key global region vulnerable to climate change; however, limited studies have focused on the combine effect of CO2 enrichment and temperature on wheat production in Sub-humid climate of eastern IGP in India. To address this issue, an Open top chamber (OTCs) experiment was conducted during 2013-14, to determine the effects of elevated atmospheric carbon dioxide (CO2) and temperature on growth, yield attributes and yield of wheat. Wheat cultivars (DBW 14 and HD 2967) were grown with four treatment combination of CO2 and temperature in OTCs, during the rabi season. The study revealed that wheat genotypes performed better under elevated CO2 condition in term of grain number, test weight and grain yield than an ambient condition. The greater biomass under elevated CO2 was brought about by an increase in radiation use efficiency (RUE) during both heading and physiological maturity periods. Elevated temperature decreased the grain yield but increase plant height compared to ambient temperature. Days to physiological maturity was reduced by 4 to 7 days in both the cultivars under elevated temperature condition and increased by 3 to 4 days under the elevated CO2 condition with respect to ambient condition. The elevated CO2 had positive effects whereas elevated temperature had negative effects on growth, yield attributes and yield of wheat. With elevation of both CO2 and temperature, elevated CO2 compensate the negative effects of elevated temperature on growth, yield attributes and yield of wheat.

Numerical Analysis of Boundary Layer Flow and Heat Transfer over a Stretching and Non-Stretching Bullet-Shaped Object

The two-dimensional axisymmetric magnetohydrodynamic boundary layer flow with heat transfer of Newtonian fluid over a stretching and non-stretching bullet-shaped object has been investigated. Therefore, fluid flow and heat transfer have been investigated in two types of flow geometries such as the thicker surface and the thinner surface of the bullet-shaped object. The present analysis also focuses on the physical relevance and accurate trends of the boundary layer profiles which are adequate in the laminar boundary layer flow. The novelty of this current work is to discuss the effect of shape and size (surface thickness parameter s) and the stretching factor of the bullet-shaped object on the fluid velocity and temperature profiles within the boundary layer region also develop the relationship between the dependent and independent parameters by the correlation coefficient. The partial differential equations of momentum and energy have been reduced to a system of non-linear ordinary differential equations along with the transformed boundary conditions by applying the local similarity transformations. These coupled non‐linear ordinary differential equations’ governing the flow field has been solved by the Spectral Quasi-Linearization Method (SQLM). The numerical analysis of the SQLM has been carried out with MATLAB for investigating the effect of various controlling parameters on the flow fields. The residual error infinity norms have been analyzed to determine the speed of convergence and accuracy of the method. The numerical results have been displayed graphically and in tabular form and the physical behavior of the problem also discussed. The investigation shows that in the case of a thicker bullet-shaped object the velocity profile does not approach the ambient condition asymptotically but intersects the axis with a steep angle and the boundary layer structure has no definite shape whereas in the case of a thinner bullet-shaped object the velocity profile converge the ambient condition asymptotically and the boundary layer structure has a definite shape. It is also noticed that thinner bullet-shaped object acts as good cooling conductor compared to thicker bullet-shaped object and the wall friction can be reduced much when thinner bullet-shaped object is used rather than the thicker bullet-shaped object in both types of non-stretching or stretching bullet-shaped object . Keywords: forced convection, correlation coefficient, multiple regression, MHD, stretching