Solution Phase Preparative Routes to Nitride Morphologies of Interest in Catalysis

This review assesses the track record and prospects of non-oxide sol–gel and solvothermal routes to nitride materials for use in catalysis. There is a strongly developing body of synthesis methods that yield highly porous materials, some with engineered pore structures, nanocrystalline materials with high surface areas and anisotropic nanocrystals that have their surface area tuned to a particular crystal face. Most of the existing catalytic work on such solution-derived nitrides has focussed on utilising base properties due to surface bound amide and imide groups in silicon (imido)nitride compositions, but there are opportunities to extend these methods to other interesting nitride compositions.     

Optimal design of liquid-solid circulating fluidized bed for continuous protein recovery

In recent years, liquid-solid circulating fluidized beds (LSCFBs) are being applied as a reactor system in a number of new applications. This study addresses optimal design of LSCFB system at the design stage for the continuous protein recovery. The operation of LSCFB system for continuous protein recovery is associated with several important objectives such as production rate and recovery of protein as well as the amount of ion exchange resin requirements, all of which need to be optimized simultaneously. In this study, an experimentally validated mathematical model was used to perform the multi-objective optimization of the LSCFB system at the design stage. In the optimization study, eight operating and design parameters were used as decision variables. These variables were chosen based on systematic sensitivity analysis of the system which showed complex interplay of the decision variables over the system performance indicators. Elitist non-dominated sorting genetic algorithm with its jumping gene adaptation (NSGA-II-aJG) was used to solve a number of two- and three-objective function optimization problems. The optimization resulted in Pareto optimal solutions, which provides a broad range of non-dominated solutions due to conflicting behavior of the decision variables on the system performance indicators. Compared to the optimization results obtained in the operating stage, the performance of the system was further improved at the design stage optimization as changes in physical dimensions of the LSCFB system can provide better performance than would have been possible by adjusting only the operating parameters.     

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.     

Oxide thickness dependence of nitridation effects on TDDB characteristics

Wet oxide thicknesses dependence of nitridation effects on electrical characteristics, charge trapping properties and TDDB (Time Dependent Dielectric Breakdown) characteristics have been investigated. It is found that the difference of conduction current between the wet and nitrided wet oxide increases with increasing oxide thickness both for negative and positive bias to the gate until constant current stress is applied. After the stress, with decreasing oxide thickness both in wet and nitrided wet oxide leakage current increases. Up to 60 Å no difference was observed between the wet and nitrided wet oxide but at 50 Å nitrided wet oxide has less increase of current comparing to the wet oxide for the same stress. In wet oxide with increasing stress current density initial hole trap decreases but electron trap increases whereas in nitrided wet oxide has less initial hole trap and also electron trap is less comparing to the wet oxide. Both in wet and nitrided wet oxide for negative bias stress, time to 50 % breakdown decreases with decreasing thickness but at 50 Å a turn-around effect was observed due to nitridation i.e., the 50 % breakdown time is greater for nitrided wet oxide comparing to the wet oxide. On the contrary, for positive bias stress 50 % breakdown time increases with decreasing oxide thickness both in wet and nitrided wet oxide. For positive bias also a turn-around effect is observed at 50 Å i.e., 50% breakdown time is less in nitrided wet oxide comparing to the wet oxide. The improved reliability of nitrided wet oxide at the thin region of 50 Å seems to be due to the increase of more Si---N bond to the interface of oxide and Si comparing to the thick oxide of above 60 Å for the same nitridation conditions.     

Thermogravimetric method for determination of oxygen stoichiometry in superconducting 1:2:3 and metal-substituted 1:2:3 compounds

The paper presents a modified thermogravimetric method for determination of oxygen stoichiometry of the oxide superconductors YBa₂Cu₃O_7−δ and metal-substituted compounds of the type YBa_2−x La _x Cu₃O_7+δ and YBa₂(Cu_1−x M _x )₃O_7−δ (M=Mg/Zn) between 25° and 930°C.     

Microstructural evolution of AISI 4340 steel during Direct Metal Deposition process

In the current investigation AISI 4340 steel was laser deposited on a rolled mild steel substrate by Direct Metal Deposition (DMD) technology. The microstructural investigation of the clad was performed using optical and electron microscopes and X-ray diffraction techniques. The microstructure consisted of ferrite, martensite and cementite phases. Two types of martensite, lathe-type and plate-type, were observed in the microstructure. Decrease in microhardness values from the top layer to the alloy layer proves that the degree of tempering of the martensite phase increases in the same direction. The lattice parameters of the identified phases were found to be shorter than those reported in literature. The reported parameters in literature are from samples processed under equilibrium conditions.     

Pore morphology in sintered ZrO2–8 mol% Y2O3 ceramic: a small-angle neutron scattering investigation

Pore morphology and pore size distribution in yttria-stabilized zirconia (ZrO₂–8 mol% Y₂O₃) have been investigated, for two sintering temperatures, namely 1200 and 1270 °C, using small-angle neutron scattering. The results show that the reduction in the porosity, at 1270 °C compared to that at 1200 °C, occurs by the elimination of the pores at the lower end of the pore size distribution. In addition, the polydispersity is also lower at 1270 °C and the nature of the distribution is altered significantly near the smaller radius range. The average pore size shifts towards the higher radius range. The specific surface area of the pores is also diminished at 1270 °C because of the elimination of the finer pores.     

Increased height gain of children fed a high-protein diet during convalescence from shigellosis: a six-month follow-Up study

The impact of dietary supplementation on catch-up growth was evaluated in 69 malnourished children ages 24-60 mo after recovery from shigellosis. They were fed either a high-protein (HP) diet with 15% of energy as protein, or a standard-protein (SP) diet with 7.5% energy as protein, for 3 wk in a metabolic study ward. Children were followed up bi-weekly for 6 mo by trained health assistants when anthropometric measurements and information of any illness were collected. Thirty-one children in the HP group and 28 children in the SP group completed 6-mo follow-up. The increase in height (mean +/- SD) was 5.3 +/- 1.0 cm vs. 4.1 +/- 1.1 cm for HP and SP groups, respectively (P < 0.001), whereas increase in body weight was 1.39 +/- 0.58 and 1.29 +/- 0.72 kg for children fed HP and SP, respectively (P = 0.59). The proportion of children who were severely stunted (< -2 SD height-for-age) decreased from 45 to 29% in the HP group compared to 50 to 46% in the SP group (P < 0.05) at 6-mo follow-up. The number of diarrheal episodes per child tended to be lower in the HP vs. SP than in the SP group (1.9 vs. 2.3, P = 0.41). These results demonstrate that feeding an HP diet to the malnourished children during recovery from shigellosis enhanced linear growth with a modest reduction in diarrheal morbidity during the 6-mo follow-up period.     

Efficient Modeling of Transmission Lines With Electromagnetic Wave Coupling by Using the Finite Difference Quadrature Method

This paper proposes an efficient numerical technique, called the finite difference quadrature (FDQ) method, to model the transmission line with radiated electromagnetic (EM) wave noise coupling. A discrete modeling approach, the FDQ method adapts coarse grid points along the transmission line to compute the finite difference between adjacent grid points. A global approximation scheme is formulated in the form of a weighted sum of quantities beyond the local grid points. Unlike the Gaussian quadrature method that computes numerical integrals by using global approximation framework, the FDQ method uses a global quadrature method to construct the approximation schemes for the computation of, however, numerical finite differences. As a global approximation technique, the FDQ method has superior numerical dispersion to the finite difference (FD) method, and, therefore, needs much sparser grid points than the FD method to achieve comparable accuracy. Equivalent voltage and current sources are derived, exciting the transmission line at the grid points. Equivalent circuit models are consequently derived to represent the transmission line subject to radiated electromagnetic wave noise. The FDQ-based equivalent models can be integrated into a simulator like SPICE.     

Chronic arsenic toxicity in west Bengal--the worst calamity in the world

Since 1983 large number of people are being encountered with arsenic toxicity due to drinking of arsenic contaminated water (0.05-3.2 mg/l) in 6 districts of West Bengal. Clinical and various laboratory investigations were carried out on 156 patients to ascertain the nature and degree of morbidity and mortality that occurred due to chronic arsenic toxicity. All the patients studied had typical rain drop like skin pigmentation (being inclusion criteria) while thickening of palm and sole were found in 65.5% patients. Other features included weakness (70%), gastro-intestinal symptoms (58.6%), involvement of respiratory system (57.08%) and nervous system (50.6%). Lung function tests showed restrictive lung disease in 53% (9/17) and combined obstructive and restrictive lung disease in 41% (7/17) of patients. Abnormal electromyography was found in 34.8% (10/29) and altered nerve conduction velocity in 34.8% (10/29) of cases. Enlargement of liver was found in 120 cases (76.9%) while splenomegaly in 31.4% cases. Liver function test showed elevated globulin level in 15.8% and alkaline phosphatase in 51.3%, alanine amino transferase (ALT) in 11.8% and aspartate amino transferase (AST) in 27.6% of cases. Evidence of portal hypertension was found in 33.3% patients. Liver biopsy reports of 45 patients showed non-cirrhotic portal fibrosis in 41, cirrhosis in 2 and normal histology in 2 cases. There was no correlation between the quantity of arsenic taken through water and the level of arsenic in hair, nail, liver tissues and the degree of fibrosis. There were 5 deaths of which one had skin cancer. The various non-cancer manifestations which were observed in these patients were much severe than those reported in similar cases in other parts of the world.