Impact of farm level corruption on the food security of households in Bangladesh

In this article, we have analyzed the impact of farm level corruption on households’ food security using survey data collected from 210 Bangladeshi rice farmers. Econometric results confirm that the cost of corruption adversely affects households’ calorie consumption. The marginal effect of corruption is higher for the low expenditure households relative to the high expenditure households. This happens because the high expenditure households exhibit more flexibility in terms of adjusting their budgets and hence, are able to cover the cost of corruption without affecting their food consumption, whereas for the low expenditure households such flexibility is limited and hence are forced to compromise on their food budget. Variables such as the better education of women and land holding also positively contribute to food security.     

Synthesis and characterization of a new NLO-active donor–acceptor-type conjugated polymer derived from 3,4-diphenylthiophene

A new donor–acceptor-type conjugated polymer (P1) carrying 3,4-diphenylthiophene, 2,5-dihexyloxybenzene, and 1,3,4-oxadiazole units was synthesized through multistep reactions. The polymer was prepared using a polyhydrazide precursor route. The polymer has a well-defined structure and exhibits good thermal stability, with a decomposition onset temperature in nitrogen of 300 °C. Cyclic voltammetry experiments revealed that the polymer has low-lying LUMO (−3.68 eV) and high-lying HOMO (−5.78 eV) energy levels. The electrochemical band gap was found to be 2.10 eV. The UV-visible absorption spectrum of the polymer presented a maximum at 373 nm, and it displayed bluish-green fluorescence in dilute chloroform solution. The nonlinear optical properties of the new polymer were investigated at 532 nm using the Z-scan technique with nanosecond laser pulses. The polymer exhibited strong optical limiting behavior due to excited state absorption, which was phenomenologically similar to a three-photon absorption (3PA) process. The 3PA coefficient γ was found to be 7 × 10⁻²² m³/W². The studies show that the new polymer (P1) is a promising material for developing efficient photonic devices.     

A new donor–acceptor type conjugative poly{2-[4-(1-cyanoethenyl)phenyl]-3-(3,4-didodecyloxythiophen-2-yl)prop-2-enenitrile}: Synthesis and NLO studies

This research article describes a technique to synthesize a new donor–acceptor type conjugated polymer carrying cyanophenylenevinylene and 3,4-didodecyloxy thiophene moieties, as an effective optical limiting material. It also includes the evaluation of its linear and nonlinear optical properties and electrochemical studies. The new polymer, viz., poly{2-[4-(1-cyanoethenyl)phenyl]-3-(3,4-didodecyloxythiophen-2-yl)prop-2-enenitrile} (P1) has been synthesized starting from 2,2′-sulfanediyldiacetic acid and diethyl ethanedioate through multistep reactions. In the final step, the polymerization was brought about by Knovenagel condensation. The newly synthesized intermediate, monomer and the polymer (P1) have been characterized by different spectroscopic techniques followed by elemental analysis. Its optical and electrochemical properties are investigated by UV–vis, fluorescence spectroscopy and cyclic voltammetric studies, respectively. The red colored polymer has a well defined structure, good thermal stability and a band gap of 1.78 eV. It emits green fluorescence both in solution and in film state. The third-order nonlinear optical property (NLO) of the polymer was studied by the Z-scan technique. The measurements were performed at 532 nm with 5 ns laser pulses using samples in solution form. An absorptive nonlinearity of the optical limiting type was found in this polymer, which is due to the combined action of saturable absorption and excited state absorption processes. These studies revealed that polymer P1 is a promising material for optical limiting applications.     

Fatigue Fracture of a Compressor Disc of an Aeroengine

There was an accident to a single engine aircraft. From the eye and ear witness accounts, it was established that the accident occurred because of engine failure. After preliminary examination of the wreckage of the crashed engine, a few suspected components were identified for detailed laboratory investigation. The objective was to establish the primary failure in the engine. While majority of the engine components submitted for laboratory analysis showed secondary damages due to either crash impact forces or post-accident fire, the fracture pattern in one of the compressor disks was different from other components of the engine. Fractographic study revealed that the failure of the disk was by fatigue mechanism. Subsequent investigation showed that the fatigue fracture of the compressor disk was the first in the chain of events that led to the engine failure. This finding was further substantiated through fracture mechanics calculations.     

Preparation and characterization of silver particulate films on softened polystyrene and poly(4-vinylpyridine) blends

Results of the investigations carried out on the optical properties of silver particulate films deposited at a rate of 0.4 nm/s on softened polystyrene and poly(4-vinylpyridine) (P4VP) blends held at 455 K are reported. Under the conditions of deposition, a sub-surface particulate structure is expected. It had been shown earlier that the morphology of the sub-surface particulate structure is dependent on polymer-metal interaction. In the present studies, an inert polymer like polystyrene (PS) is blended with an interacting polymer P4VP. The optical studies on the silver particulate films deposited on softened blends of PS/P4VP have been carried out. The results show a shift in plasmon resonance to higher wavelength with increasing P4VP concentration of the blends in comparison to that of the films deposited on pure PS. An X-ray photoelectron spectroscopy study at two different electron take off angles indicates the formation of subsurface particulate structures for films deposited on blends.     

Studies on the temperature dependence of I–V and C–V characteristics of electron irradiated silicon photo-detectors

The current transport mechanisms of n⁺–p silicon (Si) photo-detectors in different temperature and bias regions before and after irradiation with a dose of 350 kGy has been investigated and presented in this article. Temperature-dependent dark current–voltage (I–V) studies under forward and reverse bias were carried out for this purpose. In the temperature range studied, the dark current contribution in the low bias range is believed to be due to the generation-recombination of minority carriers in the space-charge region. Electron irradiation does not seem to have altered the dark current conduction mechanism. Capacitance–voltage (C–V) at various temperatures was measured to identify the presence of deep levels in the device.     

Dielectric studies on the chicken egg membrane deposited with CdS nanoparticles

Results on the studies of dielectric properties of the chicken egg membrane deposited with CdS nanoparticles are presented in this article. The CdS nanoparticles are synthesized in the membrane by the diffusion of the precursor solutions of cadmium acetate and thiourea across the membrane. The AC capacitances of the membrane were measured in the frequency range of 1 kHz–10 MHz. The capacitance of the membrane drops in the entire frequency range of measurement with the deposition of CdS nanoparticles and the extent of the drop being dependent on the reaction parameters. Drop in capacitance is highest for conditions favoring small nanoparticles. The drop in capacitance with the deposition is attributed to the presence of Cd(OH)₂ in the deposits. The volume fraction and capacitance of that component of the deposit responsible for reducing the capacitance of the deposited membrane below that of the undeposited could be estimated by assuming a simple model. X-ray photoelectron spectra (XPS) of the deposited membrane indicate that nanoparticles of CdS are not formed on the surface but formed deep in the pores of the membrane. These particles are found to be cadmium rich, thus supporting the inference that the Cd(OH)₂ is formed along with the CdS nanoparticles.     

Inhibition of the corrosion of steel in hydrochloric acid solution by some organic molecules containing the methylthiophenyl moiety

The corrosion inhibition effect of 2-[4-(methylthio) phenyl] acetohydrazide (HYD), 2-{[4-(methylthio) phenyl] acetyl} hydrazinecarbothioamide (TAD) and 5-[4-(methylthio) benzyl]-4H-1,2,4-triazole-3-thiol (TRD) on steel in 1.0 M HCl was investigated by mass loss and electrochemical methods. The effect of concentration, temperature and immersion time was studied. The results indicated that the compounds are efficient, mixed type and pursue Flory–Huggins adsorption isotherm. The inhibition efficiency at lower concentration of inhibitor decreased with temperature while at higher concentration, it is retained and the calculated free energy attributes this to comprehensive adsorption. The efficiency stands in the order TRD > TAD > HYD and is confirmed by the Quantum studies.     

An efficient pipelined architecture for real-valued Fast Fourier Transform

Real-valued Fast Fourier Transform (FFT) plays an important role in today’s digital world because of the fact that most of the signals contain real values. The FFT computation of real signals using conventional techniques requires more hardware space with high power consumption, which is the most important task for a researcher while designing VLSI architectures. This can be eradicated by clearly analysing the symmetric property of the real-valued signals. In this paper, we have adopted the symmetric property and designed an efficient pipelined architecture for 16-point DIF FFT. The pipeline scheme reduce the processing time at the cost of some registers and in order to contribute efficiently for power reduction we have modified the complex multiplier with reduced internal real multipliers which are in turn replaced by an modified canonic signed digit multiplier (CSDM) with resource-sharing technique. The complete module is synthesised and simulated using Xilinx ISE 14.1 with the target device is Virtex-5 xc5vlx110T. The experimental results verify that our implemented design is more efficient in terms of speed, area and power when comparing with similar works.