Low-Temperature Water Gas Shift Reaction on Combustion Synthesized Ce1−x Pt x O2−δ Catalyst

Catalytic activity of Pt²⁺ ion substituted CeO₂ synthesized by solution combustion method was tested for low-temperature water gas shift reaction in H₂ rich steam reformate. XPS studies show that Pt is dispersed as ions and there is no change in Pt oxidation state after the reaction. CO conversion is found to be maximum at 200 °C over Ce_1?x Pt _x O_2?δ catalysts without any methanation. The values of rate are 1.86 and 4.66 μmol/g/s at 125 and 150°C respectively with a dry gas flow rate of 6 Lh^?1 over 2% Pt/CeO₂.     

Vertically aligned Mn-doped zinc oxide nanorods by hybrid wet chemical route

Mn-doped zinc oxide (Mn:ZnO) nanorods were synthesized by incorporating manganese in aligned ZnO nanorods. For this, Mn was evaporated onto ZnO nanorods and the composite structure was subjected to rapid thermal annealing. The nanorods were preferentially oriented in (0 0 2) direction as indicated by the XRD measurement. Optical band gap was seen to decrease with increasing amount of Mn incorporation. XPS studies indicated that incorporated Mn was in Mn²⁺ and Mn⁴⁺ states. Mn²⁺ atomic concentration was found to be larger than Mn⁴⁺ concentration in all the samples. The Raman spectra of the Mn:ZnO nanorods indicated the presence of the characteristic peak at ∼438 cm⁻¹ for high frequency branch of E₂ mode of ZnO. The PL peak at ∼376 nm (∼3.29 eV) was ascribed to the band edge luminescence while the peak at ∼394 nm (∼3.15 eV) was assigned to the donor bound exciton (D^oX) and free exciton transition related to Mn²⁺ states.     

Indium phosphide films prepared by flash evaporation technique: Synthesis and characterization

Indium phosphide films were deposited by flash evaporating InP powder (99.995%) on glass substrates. Microstructural information was obtained from transmission electron microscope and atomic force microscope (AFM) studies. The average value (~ 0.33 nm) of surface roughness of the films was determined by AFM. X-ray diffraction traces indicated reflections from (111), (220) and (311) planes only. The band gap was found to vary between ~ 1.94 eV and 1.96 eV. ε_∞ varied between 11.58 and 11.89 while the plasma frequency (ω_p,) were seen to vary between 8.52 and 8.59 × 10¹⁴ s^− 1. The bonding environment in the films was determined from Raman and Fourier transformed infrared measurements. The experimental absorption spectra could be faithfully described by considering the effect of scattering by the ultra small crystallites in the film alone. Photoluminescence peak located at ~ 1.5 eV may be ascribed due to transitions from states arising out of phosphorous vacancy to the valance band. The shoulders of the peak ~ 1.5 eV may originate from the DA transitions between V_P and In_P.     

Studies in the Glyceride Composition of Partially Hydrogenated Rearranged Glycerides of Cottonseed Oil

The directed rearrangement reaction in solvents of partially hydrogenated cottonseed oil was investigated with special reference to the influence of polarity of solvents and amount of trisaturated glycerides formed. The results as obtained by selective enzymatic hydrolysis, gas liquid chromatography and infrared spectrophotometry of the whole fat triglycerides and of the corresponding monoglycerides of cottonseed oil and partially hydrogenated cottonseed oil, before and after directed interesterification, indicate a general trend of the increase of the saturated fatty acyl radicals in the 2-position of the glyceride moiety with the corresponding decrease of the unsaturated acids. The considerable decrease in the concentration of cis unsaturated acid in the 2-position of the triglycerides of partially hydrogenated cottonseed oil has been observed after the directed rearrangement reaction with the simultaneous enrichment of trans unsaturated acid. It was also observed that cottonseed oil does not show any plasticity, whereas after directed interesterification it shows remarkable plasticity. The plasticity of partially hydrogenated cottonseed oil is further diminished after directed rearrangement reaction.     

Prediction-based protein engineering of domain I of Cry2A entomocidal toxin of Bacillus thuringiensis for the enhancement of toxicity against lepidopteran insects

Issues relating to sustenance of the usefulness of genetically modified first generation Bt crop plants in the farmer's field are of great concern for crop scientists. Additional biotechnological strategies need to be in place to safeguard the possibility for yield loss of Bt crop by other lepidopteran insects that are insensitive to the Cry1A toxin, and also against the possibility for emergence of resistant insects. In this respect, Cry2A toxin has figured as a prospective candidate to be the second toxin to offer the required protection along with Cry1A. In the present study, the entomocidal potency of Cry2A toxin was enhanced through knowledge-based protein engineering of the toxin molecule. Deletion of 42 amino acid residues from the N-terminal end of the peptide followed by the replacement of Lys residues by nonpolar amino acids in the putative transmembrane region including the introduction of Pro resulted in a 4.1-6.6-fold increase in the toxicity of the peptide against three major lepidopteran insect pests of crop plants.     

Distribution of relaxation time in solution-processed polycrystalline CZTS thin films: Study of impedance spectroscopy

Here we report the complex impedance spectroscopic analysis of polycrystalline CZTS thin films synthesized by sol-gel spin coating technique without any post deposition sulphurization. The films are characterized by microstructural, compositional, optical and electrical studies to confirm the formation of kesterite phase of CZTS comprises of well distributed compact grains with the optical band gap 1.44?eV. Room temperature electrical characterizations of the CZTS thin films by four-probe and Hall effect technique revealed the p-type conductivity of the films with resistivity ~ 1.45?×?10^?2 Ω?cm, mobility ~ 3.7?×?10³ cm² V^?1 s^?1 and carrier concentration ~ 1.82?×?10¹⁷ cm^?3. The distribution of relaxation time (DRT) function with improved frequency resolution is reconstructed from the impedance spectra of CZTS film recorded in the frequency range 50?Hz to 5?MHz at room temperature to identify the number of electrical processes in the polycrystalline film. The Nyquist plot is fitted into electrical model consist of three parallel combinations of resistor (R) and capacitor (C) in series as three major peaks in DRT function indicates the presence of different relaxation processes with major contributions from core grains along with smaller contributions from grain boundary and interfaces. The room temperature frequency dependence of dielectric constant, loss tangent and ac conductivity is also studied for the CZTS films.     

All-optical binary flip-flop with the help of Terahertz Optical Asymmetric Demultiplexer

The memory device is very important as they store various values either temporary or permanently. Optical flip-flop memories form a fundamental building block for all-optical packet switches in the next generation communication networks. All-optical flip-flop memory with the help of Terahertz Optical Asymmetric Demultiplexer (TOAD) is proposed and described. Principles and possibilities of all-optical circuits for TOAD based S–R, J–K, D and T flip-flop are reported. Numerical simulation confirming described method is also given in this paper.     

Optical Diffuse Imaging of an Ex Vivo Model Cancerous Human Breast Using Independent Component Analysis

Optical imaging using independent component analysis (OPTICA) has been used for detection, 3D localization, and cross-section imaging of a tumor inside a model human breast composed of ex vivo human breast tissues. OPTICA uses a multisource target illumination and multidetector signal acquisition scheme to obtain multiple spatial and angular views of the sample for target localization. Independent component analysis of the perturbations in the spatial light intensity distribution measured on the sample boundary sorts out the signal originating from individual targets. A back-projection technique estimates the cross-section of each target. The approach correctly provided the positions of a tumor located at the mid-plane and two glandular structures located at different positions within the 33-mm thick model breast. The reconstructed cross-section images are in good agreement with known dimensions of the structures, and pathological findings.     

Water-wave Scattering by an Ice-strip

The problem of water-wave scattering by a strip of ice-cover floating on the surface of deep water is investigated here. The ice-cover is modelled as a thin elastic plate of very small thickness. The problem is reduced to that of solving two singular integral equations of Carleman type over a semi-infinite range and are solved approximately by casting them into two separate Riemann-Hilbert problems by assuming the strip width to be large. The reflection and transmission coefficients are derived approximately. Numerical results for the reflection coefficient are presented graphically against the wave number and also against the ice-cover parameter. The oscillatory nature of the reflection coefficient against the wave number as well as the ice-cover parameter is found to be one of the main features of the curves. It is also seen that, in the limiting case when the ice-cover parameter tends to zero (i.e., the ice-cover is almost absent), the amount of reflection is negligible