Structural studies on Si:H network by Raman, micro-photoluminescence, electron microscopy and ultraviolet ellipsometry: effect of Ar dilution to the SiH4-plasma

Structural characterization of the material has been performed using micro-Raman spectroscopy, ultraviolet (UV) ellipsometry, electron microscopy and micro-photoluminescence (PL) studies on Si:H films prepared at a wide range of Ar dilution to the SiH₄ plasma, defined by R(Ar)=Ar/SiH₄ and varying from 10 to 400. Microcrystallization in Si:H network was easily obtained introducing Ar as a diluent, however, increasing Ar dilution revealed a continuous transformation of the network from microcrystalline to amorphous dominated structure. An overall amorphization of the network and its initiation by the presence of an enormously high void density (∼81 vol.%) in an extended incubation layer (∼163 nm) is the result of extremely high Ar dilution (R(Ar)∼400), on the formation of Si:H films. Increasing porosity in the amorphous dominated matrix resulted in a significant increase in the photoluminescence intensity, contributing to a photoluminescent Si:H material available from extremely high Ar dilution to the SiH₄ plasma in rf glow discharge. Effect of Ar dilution inducing the growth morphology by controlling both the gas phase reactions and solid phase network modifications in Si:H network has been discussed.     

Morphology,Mineralogy and Mixing of Individual Atmospheric Particles Over Kanpur (IGP): Relevance of Homogeneous Equivalent Sphere Approximation in Radiative Models

Estimation of the direct radiative forcing (DRF) by atmospheric particles is uncertain to a large extent owing to uncertainties in their morphology (shape and size), mixing states, and chemical composition. A region-specific database of the aforementioned physico-chemical properties (at individual particle level) is necessary to improve numerically-estimated optical and radiative properties. Till date, there is no detailed observation of the above mentioned properties over Kanpur in the Indo-Gangetic Plain (IGP). To fill this gap, an experiment was carried out at Kanpur (IITK; 26.52°N, 80.23°E, 142 m msl), India from April to July, 2011. Particle types broadly classified as (a) Cu-rich particles mixed with carbon and sulphur (b) dust and clays mixed with carbonaceous species (c) Fe-rich particles mixed with carbon and sulfur and (d) calcite (CaCO₃) particles aged with nitrate, were observed. The frequency distributions of aspect ratio (AR; indicator of extent of particle non-sphericity) of total 708 particles from April to June reveal that particles with aspect ratio range >1.2 to ≤1.4 were abundant throughout the experiment except during June when it was found to shift to high AR range, >1.4 to ≤1.6 (followed with another peak of AR i.e. >2 to ≤2.4) due to dust storm conditions enhancing the occurrence of more non-spherical particles over the sampling site. The spherical particles (and close to spherical shape; AR range, 1.0 to ≤1.2) were found to be <20% throughout the experiment with a minimum (11.5%) during June. Consideration of Homogeneous Equivalent Sphere Approximation (HESA) in the optical/radiative model over the study region is found to be irrelevant during the campaign.     

Experimental study of paddy drying in a vortex chamber

The intensification of interfacial mass, heat, and momentum transfer makes vortex chambers potentially interesting for the efficient drying of paddy, allowing shorter drying times and/or more compact equipment. The presence of a shell introduces particular challenges. Intraparticle diffusion limitations are strong and may reduce the advantage from intensified interfacial mass and heat transfer and the efficiency of air usage. Furthermore, high shear and normal stresses in the fast rotating particle bed may cause damage to the paddy shell, posing problems for transport and storage. With these specific aspects in mind, the use of vortex chambers for paddy drying is experimentally evaluated.     

Evaluation of surface/interface quality,microstructure and mechanical properties of hybrid additive-subtractive aluminium parts

A disadvantage of selective laser melting (SLM) processes for the manufacture of large parts is their slow build time per unit volume. A hybrid route is to generate core simple shapes traditionally, for example by machining, followed by adding final features by SLM. Here the mechanical integrity of such hybrid parts is studied, choosing the building of AlSi10Mg by SLM on a machined AA6082 base, in the shape of a tensile test piece, as a simple example. These materials are chosen for their relevance to lightweight parts. As-built parts fail at the SLM/machined interface but standard heat treatments transfer failures to the machined material. Optimised SLM processing conditions and microstructures of the SLM and interfacial regions are reported.     

Isolation and identification of phosphate‐solubilizing microorganisms and distribution of orthophosphate in different seasons from sewage‐fed East Kolkata Wetland

This study focused on isolation and identification of possible phosphate‐solubilizing bacteria (PSB ) from the sewage‐fed East Kolkata Wetland (EKWL ), a prospective water resource for pisciculture. In addition, different limnological parameters have been correlated with orthophosphate and seasonal variations. PSB have been isolated in Pikovskaya medium and identified morphologically and biochemically and finally analysed by 16S rDNA gene sequence. Limnological studies involving temperature (potentiometric), pH (potentiometric), dissolved oxygen (iodometric), ammonia‐nitrogen (spectrophotometric) and orthophosphate (spectrophotometric) concentrations were conducted. The results of this study established the presence of Bacillus megaterium , a potential PSB in EKWL . The activity of B. megaterium is also supported by the seasonal orthophosphate variations. The changes in concentration of other limnological parameters were also prominent. The water quality parameters of temperature (r  = 0.886), dissolved oxygen (r  = 0.729) and ammonia‐nitrogen (r  = 0.396) concentrations exhibited a positive correlation with orthophosphate and a negative correlation with pH (r  = ?0.699). The B. megaterium obtained in this study, exhibited a significant alteration in regard to orthophosphate content and relationships with other factors. Further experiment on the soluble phosphorus solubilization potential of B. megaterium revealed the biological availability of phosphorus was increased by threefold after 120 hr of incubation, with the decreasing pH value, although the phytase activity was 0.419 U/ml. PSB have a vital function in plant nutrition in supplying phosphate, essential nutrients and its uptake results in appropriate functioning and metabolism of different aquatic plants and organisms. PSB are competent biofertilizer to amplify aquaculture production for sustainable development.     

Analysis of mineral composition of some Assam and Darjeeling black teas

Black teas manufactured in Darjeeling and Assam were analysed for various macrominerals such as P, K, Ca, Mg and microminerals such as Mn, Fe and Cu. A considerable amount of minerals, eg K (40-46 mg), Mg (2.7-3.0 mg), Ca (0.48-0.66 mg) and traces of Mn (0.28-0.40 mg), Fe (0.16-0.20 mg), P (29-41 μg) and Cu (12-22 μg) were found in a cup of black tea brew. Black teas manufactured from the leaf coming from a pruned section and fine portion usually showed higher mineral content than tea manufactured from unpruned sections and coarse grade teas of Darjeeling. Assam CTC tea was found to be richer in mineral content compared to Darjeeling orthodox tea.     

Dielectric properties of vacuum-deposited bismuth oxide films

The dielectric properties of bismuth oxide films prepared by vacuum deposition have been studied in the frequency range 0.1–10 kHz and the temperature range 90–298.5 K. The capacitances C_p and C_s and the loss factor show dependences on the frequency, temperature and aging of the samples. The loss factor exhibits a flat maximum in its temperature variation curve at about 170 K. Interfacial polarization, which is caused by the excess bismuth and by various defects and impurities, is thought to be the main relaxation mechanism operating in the low frequency region.     

Comparative delivery of Diltiazem hydrochloride through synthesized polymer: Hydrogel and hydrogel microspheres

In this study, interpenetrating polymer network (IPN) hydrogel based on polyvinyl alcohol (PVA) networking with polyacrylic acid (PAA) were prepared by a non‐conventional emulsion method without any added crosslinker, using benzoyl peroxide as initiator and sodium chloride (NaCl) as additive. The IPN hydrogel was characterized by using Fourier transformed infrared (FTIR) spectrophotometry, Thermo gravimetric analysis (TGA), and Scanning electron microscopy (SEM). (PVA‐co‐PAA)/NaCl normal IPN hydrogel (H) were fabricated into hydrogel microspheres (HM) by modified emulsion crosslinking method using glutaraldehyde‐saturated toluene as crosslinker and were loaded with Diltiazem hydrochloride (DL). The IPN hydrogel showed more swelling in simulated intestinal fluid (SIF). (PVA‐co‐PAA)/NaCl HM formulation A1 showed comparatively higher DL entrapment (79%) and better control over DL release up to 24 h. By comparing antihypertensive activity of DL loaded two formulations in normotensive rats, HM formulation A1 found more effective in reducing blood pressure to 40.1%. The experimental results demonstrated that (PVA‐co‐PAA)/NaCl HM had the greater potential than normal hydrogel to be used as a drug carrier. A single use of the prepared hydrogel microsphere system of DL can effectively control hypertension in rats. The system holds promise for clinical studies. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Will capacity building training interventions given to street food vendors give us safer food?: A cross-sectional study from India

Successful food hygiene training and the consent of safe food handling practices learnt during training are critical elements in the control of food-borne illnesses throughout the world. It is true for food handlers and vendors belonging to all sectors. But, it is all the more urgent for street vendors because they are more exposed to environmental hazards and are predominantly from much weaker socio-economic backgrounds and yet cater to the general mass. Using a cross-sectional study design a sample of 80 street food vendors were selected and provided with training to evaluate the existing Knowledge, Attitude and Practice (KAP) regarding food safety and hygiene and the change of the same after training interventions. Responses regarding KAP on food safety and hygiene before and after training revealed that there was a significant change in their perception to food safety knowledge and also practices. The knowledge level of the food vendors increased from an average 24.35%–66.2% after training interventions. The overall performance rating of full adoption of good hygiene practices by the vendors ranged from 37.5% to 50.8% in post-training period.     

Promotion of microcrystallization by argon in moderately hydrogen diluted silane plasma

Using argon as a diluent of SiH₄, undoped hydrogenated microcrystalline silicon (μc-Si:H) films, having σ_D10⁻⁵ S cm⁻¹, were prepared at a very high deposition rate of 36 Å/min. Micrograins were identified with several well-defined crystallographic orientations. The effect of variation of Ar-dilution on the electrical and structural properties of Si:H films were studied systematically. Addition of H₂ to the Ar-diluted SiH₄ plasma improved the network structure by eliminating defects, introducing structural reorientation and grain growth, although, reducing the deposition rate. Accordingly, highly conducting (σ_D10⁻³S cm⁻¹) undoped μc-Si:H film was achieved utilizing energy released by de-excitation of metastable state of Ar (denoted as Ar*), in association with network modulation by atomic hydrogen in the plasma.