Synthesis and photovoltaic device studies of azo‐linked low‐bandgap polymers

We report the synthesis of a series of new polymers containing azo linkage as a part of the main chain. The monomer 1,2‐bis(7‐bromo‐9,9‐dioctyl‐9H ‐fluoren‐2‐yl)diazene was synthesized using a precursor approach which avoids non‐selective bromination and was copolymerized with various donor or acceptor units. The homopolymer poly[1,2‐bis(9,9‐dioctyl‐9H ‐fluoren‐2‐yl)diazene] ( P1 ) as well as the copolymers poly[1‐(9,9‐dioctyl‐9H ‐fluoren‐2‐yl)‐2‐(9,9,9′,9′‐tetraoctyl‐9H ,9′H ‐[2,2′‐bifluoren]‐7‐yl)diazene] ( P2 ), poly[1‐(9,9‐dioctyl‐7‐(4‐octylthiophen‐2‐yl)‐9H ‐fluoren‐2‐yl)‐2‐(9,9‐dioctyl‐9H ‐fluoren‐2‐yl)diazene] ( P3 ) and poly[4‐(7‐((9,9‐dioctyl‐9H ‐fluoren‐2‐yl)diazenyl)‐9,9‐dioctyl‐9H ‐fluoren‐2‐yl)benzo[c ][1,2,5]thiadiazole] ( P4 ) were synthesized by Suzuki polymerization. The copolymers poly[1‐(7‐(4,4‐dioctyl‐4H ‐cyclopenta[1,2‐b :5,4‐b ′]dithiophen‐2‐yl)‐9,9‐dioctyl‐9H ‐fluoren‐2‐yl)‐2‐(9,9‐dioctyl‐9H ‐fluoren‐2‐yl)diazene] ( P5 ) and poly[4‐(5‐(7‐((9,9‐dioctyl‐9H ‐fluoren‐2‐yl)diazenyl)‐9,9‐dioctyl‐9H ‐fluoren‐2‐yl)‐4‐octylthiophen‐2‐yl)‐7‐(4‐octylthiophen‐2‐yl)benzo[c ][1,2,5]thiadiazole] ( P6 ) were synthesized by direct arylation polymerization reaction. Polymers synthesized using the direct arylation method show good molecular weight, with absorption maxima in the range 500 to 532 nm. P5 and P6 possess low optical bandgaps of 1.81 and 1.86 eV, respectively. A power conversion efficiency of 0.53% with open circuit voltage of 0.53 V, short circuit current density of 3.1 mA cm^?2 and fill factor of 29% has been achieved with C71‐PCBM as acceptor in bulk heterojunction solar cells fabricated with P5 as donor. © 2016 Society of Chemical Industry     

Linseed oil as a potential resource for bio-diesel: A review

The energy crisis contributed to the development of bio-diesel production. Petroleum, charcoal and natural gas sources are limited and will be exhausted by the next century. Thus, looking for alternative source of energy is of vital importance Vegetable oils are a renewable and potentially inexhaustible source of energy with an energetic content close to diesel fuel. In recent years, bio-diesel has become more attractive as an alternative fuels for diesel engine because of its environmental benefits and it is made from renewable resource. Since edible oil demand is higher than its domestic production; there is no possibility of diverting this oil for production of bio-diesel in India. Being a tropical country, India is rich in forest resources having a wide range of trees, which yield a significant quantity of oilseeds. India is importing crude petroleum & petroleum products from Gulf countries. Indian scientists searched for an alternate to diesel fuel to preserve global environment and to withstand economical crisis. This review paper describes the production of linseed oil, its properties, composition and future potential for bio-diesel. Linseed plant contains high amount of oil in its seeds which can be converted to bio-diesel. Fatty acid compositions of linseed reported in literature are provided in this review. In this study the properties of methyl ester of linseed oil are compared with the properties of fossil diesel. The objective of this review is to give an update on the linseed plant, the production of bio-diesel from the linseed oil and research attempts to improve the technology of converting linseed oil to bio-diesel and the fuel properties of linseed bio-diesel. The technological methods that can be used to produce bio-diesel are presented together with their advantage and disadvantages. Many other areas that need to be researched on linseed oil are pointed out in this review.     

Optimal design of symmetric fractional delay filter using firefly algorithm

A fractional delay filter is used to increase the accuracy, preciseness, time synchronization, and stability of signal processing system. However, designing a fractional delay filter for a specified delay, without affecting spectral characteristics of the signal is challenging because of nondifferentiability and multimodal nature of its objective function. In this paper, a more accurate design technique has been proposed for designing fractional delay filters, based on a recently developed firefly algorithm and its improved version. The designed filters offer variable fractional delay. A novel symmetric structure of implementation has been used to design filters. The efficacy of the proposed technique is evaluated by considering a filter design example. The performance of the proposed technique is compared with the other exiting algorithm. The comparative analysis of finite impulse response (FIR) fractional delay filter design proves that the proposed algorithm has a smaller design error and an implementation complexity than the other reported existing algorithms. In addition to this, the designed FIR fractional delay filter is implemented on Xilinx Virtex-7 for experimental validation.     

Child–smartphone interaction: relevance and positive and negative implications

Universal Access in the Information Society - An increasing number of children are now using smartphones, and the phenomenon is being studied keenly by computer scientists, pediatricians,...     

Significance of thermal radiation on dusty fluid flow over a stretching rotating disk with convective boundary condition

This paper explores the flow of dusty fluid over a stretching rotating disk with thermal radiation. Further, the convective boundary condition is considered in this modeling. The described governing equations are reduced to ordinary differential equations by using apt similarity transformations and then they are numerically solved using Runge–Kutta–Fehlberg-45 scheme. To gain a clear understanding of the current boundary layer flow problem, the graphical results of the velocity and thermal profiles, shear stresses at the disk, and Nusselt number are drawn. Results reveal that the increase in the value of the porosity parameter reduces the velocity of both particle and fluid phases. The increase in the value of the Biot number improves the temperature gradient of both particle and fluid phases. The rise in the value of the radiation parameter advances the heat transference of both phases. The rise in the value of the Biot number improves the rate of heat transfer. Finally, increasing the value of the radiation parameter improves the rate of heat transfer.     

Response surface analysis and extrusion process optimisation of maize–mungbean‐based instant weaning food

This study was conducted to produce high‐quality weaning food from easily available and low‐cost raw materials by extrusion technology. Weaning mix was developed using extrudates of maize (Zea mays) and mungbean (Vigna radiata) flour with a twin‐screw extruder. Experiments were designed using three independent variables [feed moisture (12.6 – 19.4%), screw speed (349 – 601 rpm) and barrel temperature (108 – 192 °C)] and five dependent variables (specific mechanical energy, bulk density, water absorption index, water solubility index and degree of gelatinisation) at five levels of central composite rotatable design (CCRD). Optimisation results indicated that feed moisture of 14.33%, screw speed of 524 rpm and barrel temperature of 174 °C would produce maize–mungbean extrudates of preferable functional properties. The optimised weaning mix contained maize–mungbean extrudates 40%, skim milk powder 35% and sugar 25% (w/w). The nutrient content of the weaning mix was in accordance with the standards specified by PFA, (2004) with high protein and starch digestibility.