Structural and optical properties of layer-by-layer solution deposited Cu2SnS3 films

Cu₂SnS₃ (CTS) is a simple and potential material for low-cost thin film solar cells. The present work incorporates the study of changes in structural and optical properties of layer-by-layer solution deposited CTS films with annealing. Raman spectroscopy is used to ascertain structural modification upon annealing. Increase in annealing temperature leads to a structural transition from tetragonal to cubic phase. Effect of annealing on optical properties of the films is evaluated in the wavelength range of 400–2,400 nm. It is proposed that layer-by-layer growth method fundamentally defines the optical behaviour of these films. Optical constants and parameters such as refractive indices, dielectric constants and electron energy loss function are calculated from transmittance and reflectance data. The refractive indices, n and k are determined to be in ranges of 1.8–2.2 and 0.18–1.2, respectively. The real and imaginary dielectric constants vary from 1.5 to 4.6 and 0.7 to 5, respectively. Dispersion of refractive index is analyzed using two different theoretical models of Wemple–diDomenico and Spitzer–Fan.     

Electronic structure of YBa2Cu3O7 and YBa2Cu3O6—charge-self-consistent band structure calculations

Charge self-consistent LCAO band structure (CSCBS) calculations are reported for orthorhombic YBa₂Cu₃O₇ and tetragonal YBa₂Cu₃O₆ assuming ordered vacancy models. The effective atomic charges are used to study the charge transfer. In YBa₂Cu(1)₁Cu(2)₂O₇, the two types of copper atoms have their energy bands almost overlapping with effective valency of each copper as 7/3 (or effective valency of each oxygen as approximately — 13/7), so that electron hopping can take place without any loss or gain of energy while in YBa₂Cu(1)₁Cu(2)₂O₆, Cu(1)₁ is monovalent and Cu(2)₂ are divalent with significant difference in their bands. Therefore, YBa₂Cu₃O₇ should conduct much better compared to YBa₂Cu₃O₆. This corroborates the experimental observations that YBa₂Cu₃O₇ is a (super)conductor while YBa₂Cu₃O₆ is not. The calculated effective charges and DOS support the above view.     

Freeze concentration of fruit juices

Concentration of aqueous foods such as fruit juices, milk, beer, wine, coffee, and tea, is a major unit operation in the food industry. Technically feasible processes that are commercially available for the concentration of liquid foods include evaporation, freeze concentration, reverse osmosis, and ultrafiltration. Evaporation is considered to be the most economical and most widely used method of concentration. However, it is not suited for food products with very delicate flavors. Commercial processes for the concentration of such products by membrane separation techniques are not yet available. As compared to the conventional evaporation processes, concentration by freezing is potentially a superior and economic process for aroma-rich liquid foods. In the past, the process, however, was seldom used because of the investment cost and the considerable loss of concentrate in the withdrawn ice, and hence, the quality. Recent technological developments have minimized these two drawbacks associated with the earlier freeze concentration processes. In the coming decade, freeze concentration is seen as a potentially attractive method for the concentration of aroma-rich liquid foods, including fruit juices, coffee, tea, and selected alcoholic beverages. In this article, several aspects of the theoretical considerations behind freeze concentration of fruit juices, the development of new and cheaper designs, and commercially available freeze concentration processes are reviewed. The economics of the process and its application to several other areas of the food industry are also discussed.     

Advances in Seed Protein Research: A Perspective on Seed Allergens

For various reasons, a considerable majority of the global population must rely on plant proteins obtained from cereals, legumes (including oilseeds), fruits, vegetables, and nuts to satisfy dietary protein needs and requirements. Edible seeds are a significant source of proteins in livestock production and in the manufacture of pet foods. In addition, edible seeds are important sources of carbohydrates (including dietary fiber), minerals, and certain vitamins in human and animal food supply. For various reasons, edible seeds are underutilized as human food. To fully exploit this renewable natural resource to its full potential, focused research efforts are warranted. With increased number of seed proteins being identified as food allergens, renewed interest in seed proteins is evident. In this article, a brief overview of seed proteins with special reference to their allergenicity is provided. An attempt is made to identify areas needing further research.     

Walnuts (Juglans regia L): proximate composition,protein solubility,protein amino acid composition and protein in vitro digestibility

Walnuts contained 16.66% protein and 66.90% lipids on a dry weight basis. Non‐protein nitrogen values ranged from 6.24 to 8.45% of the total nitrogen when the trichloroacetic acid concentration was varied within the range 0.25–1.0 M . Albumin, globulin, prolamin and glutelin respectively accounted for 6.81, 17.57, 5.33 and 70.11% of the total walnut proteins. Walnut proteins were minimally soluble at pH 4.0. The majority of total walnut protein polypeptides had estimated molecular weights in the range 12 000–67 000. The Stokes radius of the major protein in walnuts (glutelin fraction) was 66.44 ± 1.39 Å. Lysine was the first limiting essential amino acid in total walnut proteins as well as in the globulin and glutelin fractions. Leucine and methionine plus cysteine were the second limiting essential amino acids respectively for the prolamin and albumin fractions. Hydrophobic and acidic amino acids dominated the amino acid composition in all protein fractions. Native and heat‐denatured walnut glutelins were easily hydrolysed by trypsin, chymotrypsin and pepsin in vitro. © 2000 Society of Chemical Industry     

Study of a supersonic thermal plasma expansion process for synthesis of nanostructured TiO2

The paper reports the application of supersonic thermal plasma expansion technique for controlled chemical synthesis of non-agglomerated, mono-dispersed nanoparticles of TiO₂ and also deposition of a nanocrystalline porous coating in a single-step, continuous process. The phase transformation of the nanoparticles was investigated as a function of feed rates of the basic reactants. The possibility of the particle charging and its consequences are also discussed. The grain structure of the coating was found to retain the characteristics of the seed nanoparticles. Optical Emission Spectroscopy performed at the injection section of the reactor identified the presence of TiO and TiCl molecules, which are suspected to be intermediates in this chemical route.     

Optimization of electrostatically actuated miniature compressors for electronics cooling

This paper explores the feasibility of using electrostatically actuated diaphragm compressors in a miniature-scale refrigeration system for electronics cooling. A previously developed experimentally validated analytical model for the diaphragm compressor is used in conjunction with an optimization approach to determine the required dimensions for the compressor. The analysis reveals that the pressure rise and volume flow rate required for the electronics cooling application are not achieved using a single compressor because of material property limitations. A three-dimensional array of compressors is proposed instead with which the cooling requirements and the size restrictions for electronics cooling applications may be simultaneously satisfied.     

A Bayesian Approach to the Scheduling of Preventive Maintenance

This paper presents a Bayesian model for determining minimum cost rate preventive maintenance schedules where historical data are not available. Also, a model to determine appropriate maintenance budgeting policies is presented and discussed.     

Chemical,nutritional and physiological aspects of dry bean carbohydrates—A review

The current knowledge of dry bean carbohydrates related to their composition, nutritional value and physiological attributes in humans is reviewed. Dry bean carbohydrates represent up to 60% of the total seed weight and starch is the major constituent. Molecular and physicochemical properties of legume starches are also discussed. Data to indicate the possible involvement of the raffinose family of oligosaccharides in flatulence production are given.