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A crystallographic model was developed to represent epitaxy of GaN on (1120) sapphire. The (1102) cleavage plane in sapphire was found to extend to the GaN lattice as the (1120) plane, encouraging the formation of cleaved facets. Even though the lattice mismatch is much smaller than in the case of epitaxy on (0001), the difference in the planar symmetry produced high-strained bonds near the interface.

A study was conducted to analyze long range atomic ordering in InGaN films prepared by molecular beam epitaxy on A-plan sapphire. The films were prepared using a three-step process. The sapphire substrates were nitridated by exposing their surface to an electron cyclotron resonance nitrogen plasma at 800 degrees C. X-ray diffraction experiments were carried out on a four-circle, double crystal diffractometer. Experimental results indicated that the degree of ordering correlated with increases in growth rate.

A study was conducted to elucidate the long-range atomic ordering and phase separation processes in InGaN alloys grown by molecular beam epitaxy. Results revealed that films produced at substrate temperatures from 700 to 750 degrees C with indium concentration greater than 35% exhibit phase separation. Moreover, films produced at substrate temperatures from 650 up to 675 degrees C showed compositional inhomogeneity when the indium content was higher than 25%.

An analysis of the association between the electrical properties and microstructure of YBa2Cu3O(7-x) thin films established a quantitative relation between substrate temperature and critical temperature (TC), normal-state resistivity rho, JC, orientation patterns, X-ray diffraction peak width, lattice width, microwave surface resistance and penetration depth lambda. A rise in substrate temperature to an enhanced TC and a decline in rho value increased JC value and grainsize. It also increased the ratio of c-axis- to a-axis oriented grains.

The interfacial strengths of the FeCrAl/Al2O3 and FeCrAlY/Al2O3 interfaces in both as-deposited and annealed state were measured quantitatively by the laser spallation technique. The results show that in the as-deposited state, the presence of Y significantly improved the interfacial strength from 330±31 to 686±36 MPa. However, after annealing the films at 850 °C for 16 h, the interfacial strength of the Y-free samples increased to 545±68 MPa, while the interfacial strength of Y-containing sample decreased to 599±22 MPa. The increase in the interfacial strength of the Y-free films was attributed to an improvement in the crystalline quality of the interface. The decrease in interfacial strength of the annealed Y-containing film in spite of the improvement in the crystalline quality of the interface was attributed to the depletion of Y at the interface due to formation of yttrium oxide precipitates. This is further proved that the presence of Y improves the strength of FeCrAl/Al2O3 interfaces significantly. [Copyright &y& Elsevier]

A study was carried out on the causes of liquefaction of tamarind kernel (TK) paste used in jute warp sizing. Mill- decomposed pastes, added as inocula to fresh paste, strongly liquefied the latter under aerobic as well as crudely anaerobic conditions. Aerobic bacteria isolated from mill pastes were mostly unable to liquefy, either singly or jointly. On the other hand, 9 of the 11 fungal species tested (some isolated from mill pastes) caused strong liquefaction. The enzymes in the crude filtrates of some of these liquefied TK paste at a faster rate than mineral acids at boil. In laboratory experi ments simulating mill conditions of sizing, these results were generally confirmed, fungal action being much stronger than bacterial. Aspergillus fumigatus and its enzyme were the most potent. Accumulated fungal enzymes appear to be the chief cause of liquefaction in mills. While the strongly liquefying fungi could be inhibited by small doses of common antiseptics, these had little effect on their enzymes. Sodium sulfide at 0.16% concentration inhibited all these enzymes. [ABSTRACT FROM PUBLISHER]

The article presents the study investigating the effects of several environmental factors in the growth of selected fungal species from the previous study conducted by S. N. Basu. Aspergillus terreus, Aspergillus fumigatus, Penicillium islandicum, Stachybotrys atra and Chaetomium indicum were chosen for their strong action in jute fabric and cellulose. Paecilomyces varioti, Trichoderma viride and Penicillium citrinum displayed strong growth on jute but weak on filter paper. The effects of temperature, pH, source of nitrogen, growth factors and nature of cellulosic substrate on the growth of these microorganisms were evaluated.

The article presents the study investigating the various species of lower fungi and their ability to decompose jute fiber and cellulose. Fungi were grown in test tubes on pieces of jute fabric with distilled water, on ordinary filter paper with Czapek-Dox salt solution and on 3 percent maize starch paste. The extent of growth was evaluated with the production of stains and acids. It was found out that many of these microorganisms grew well in filter paper and jute fabric. There were species that may cause stains.

The article features the detection and estimation of damage in jute fiber. A number of approved techniques on the detection and estimation of damage on textile fibers are available for the more commonly used fibers such as cotton, flax, wool and silk. The recognition of damage is straightforward when serious destruction of the fiber has occurred so that it can be seen visually, but in many cases it is not easy to detect slight or incipient damage, which, if not checked, may lead to marked deterioration of the finished products. The methods used for detection of damage, particularly slight damage, are generally based on microscopical examination, color reactions, physical tests such as solubility, and chemical tests.

Mildew stains in jute materials are usually produced by certain "superficial" species of fungi belonging to the genera Penicillium and Aspergillus, which cause little or no loss in strength. Metabolic acids, often produced simultaneously, may deepen the stain, and one fungus produced enough oxalic acid to cause acid staining. Apart from metabolic pigments, stains may be caused by colorless products combining with the non-cellulosic fractions of jute. This and the fact that superficial fungi grow more easily on jute than cotton render the former more susceptible to mildew staining. Other species which failed to produce stain in inoculation experiments but gave strongly staining filtrates may be implicated in the staining of jute. For some unknown reason, sacking proved less susceptible to staining than other fabric materials. [ABSTRACT FROM PUBLISHER]