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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]

FeCrAl/Al2O3 and FeCrAlY/Al2O3 interfaces were formed by sputter deposition of alloy thin films on A-plane sapphire substrates. The microstructure of both Y-containing and Y-free films consisted of single-phase BCC columnar grains of fairly uniform composition across the film thickness. Both films exhibited a high degree of 〈110〉 texture along the growth direction normal to the interface with no preferred in-plane orientation. In both cases, a thin amorphous layer was observed at the interface in the as-deposited state. Annealing the films for 16 h at 850 °C improved the crystalline quality of the film/substrate interface and led to grain growth within the films. The annealing did not lead to any significant changes in the film composition in the Y-free film. In the Y-containing film, yttrium oxide precipitates formed in the near interface region, depleting the adjacent alloy matrix of Y completely; accompanied by a significant enhancement of Al in the film, very close to the interface. [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]

In a study of the structural changes brought about in the jute fiber by fungal attack, generally a correlation was found between such change, on the one hand, and growth inside the lumen and fiber damage, on the other. Cracks across the fiber cells were a common feature, and complete breaks were sometimes found. External surface damage was never seen except in a few mill-damaged samples, although ultimate cells pre separated before attack showed such damage. Internal damage along the lumen was noted in samples which showed lumen growth, and sometimes even with species not growing within the fiber. Soil bacteria caused cracks across the cell, as well as internal and external corrosion. Damage caused by fungal culture filtrates was often different from and less intense than that in in vivo attack, although with preseparated Jute ulti mates complete dissolution was sometimes seen. [ABSTRACT FROM PUBLISHER]

A technique has been developed for detecting fungal growth on and inside the jute fiber by the differential staining of hyphae and fibers with Chlorazol Sky Blue stain. The test is also applicable to cotton. Growth inside the lumen is not a universal feature of fungal attack on jute, although nearly all the dark-colored fungi tested showed this property. which is not ordinarily lost or gained by changing external conditions of growth or by modifying the fiber. The minimum period required for lumen invasion has been found to be different for different species. Some of these fungi showed com paratively weak growth within the cotton fiber. Fungi growing within the lumen of jute seem to penetrate the fiber cell wall apparently at random, not at weak points nor through open ends. The active organisms attacking jute under different practical con ditions of damage have been found to be different. Granular bodies sometimes seen within the lumen of raw jute have been isolated and traced to a Bacillus species. [ABSTRACT FROM PUBLISHER]

Investigates the microstructure of YBa[sub 2]Cu[sub 3]O[sub 7-delta] thin films deposited on (001) LaAlO[sub 3] substrates by a laser ablation process. Orientation of the film with the c-axis perpendicular to the surface; Transition to grains; Crystal growth anisotropy and retained strain.