The dislocation anharmonicity in silicon

The effect of the dislocation anharmonicity on the Young modulus in bending silicon single crystals was studied. It is shown that changes in the Young modulus are caused by the contribution of dislocations to the fourth-order elasticity moduli. It is revealed experimentally that the bending deformation in both donor and acceptor silicon crystals favors the appearance mainly of the edge dislocations with the axes forming an angle θ∼90° with the Burgers vector.     

Pulmonary function changes after nebulised and intravenous frusemide in ventilated premature infants

AIMS: To compare the effects of a single dose of frusemide administered either intravenously or by nebulisation on pulmonary mechanics in premature infants with evolving chronic lung disease. METHODS: The effect of frusemide on pulmonary mechanics was studied at a median postnatal age of 23 (range 14-52) days in 19 premature infants at 24 to 30 weeks gestational age, who had been dependent on mechanical ventilation since birth. Frusemide (1 mg/kg/body weight) was administered, in random order, intravenously and by nebulisation, on two separate occasions 24 hours apart. Pulmonary function studies were performed before and at 30, 60, and 120 minutes after administration of frusemide. Urine was collected for six hours immediately before and for six hours after administration of frusemide. RESULTS: Nebulised frusemide increased the tidal volume 31 (SE 11.5)% and compliance 34 (SE 12)% after two hours, whereas no change in either was noted for up to two hours after intravenous frusemide administration. Neither intravenous nor nebulised frusemide had any effect on airway resistance. Six hour urine output increased from a mean (SE) of 3.3 (0.4) ml/kg/hour to 5.9 (0.8) ml/kg/hour following intravenous frusemide administration while nebulised frusemide had no effect on urine output. Urinary sodium, potassium, and chloride losses were also significantly higher after intravenous frusemide, whereas nebulised frusemide did not increase urinary electrolyte losses. CONCLUSION: Single dose nebulised frusemide improves pulmonary function in premature infants with evolving chronic lung disease without adverse effects on fluid and electrolyte balance.     

The role of selectins in Drosophila eye and bristle development

Mutations in the furrowed (fw) gene of Drosophila result in defects in the development of the eye and mechanosensory bristles. The eyes are reduced in size, have furrows or crevices in the retina, and show a disturbed patterning of ommatidia. In addition, the ommatidia have an altered morphology and often contain abnormal numbers of cells. The bristles show altered structure and polarity, and are occasionally duplicated or missing. These results suggest that the product of thefw gene is involved in cell determination events within sensory organs. Thefw gene has been cloned and shown to encode a protein homologous to vertebrate selectins. Like selectins, Fw contains a lectin-binding domain, ten complement binding repeats, and a transmembrane domain. The Fw protein is expressed in the larval imaginal discs where it might mediate carbohydrate-protein interactions necessary for proper development of a subset of adult sensory organs.     

Variation of the adsorption properties of porous silicon in the course of natural and high-temperature aging

The photo-and thermostimulated adsorption-desorption processes on the surface of porous silicon (por-Si) were studied in the course of natural and high-temperature degradation of the samples. The results of IR absorption, luminescence, and Auger electron spectroscopy measurements indicate that an active stage in the sample morphology variation under the natural aging conditions lasts for a prolonged time (exceeding 74 days) upon the por-Si layer formation and is accompanied by redistribution of the adsorbed molecules. The surface properties vary so as to favor the adsorption of oxygen, carbon, and, probably, OH groups. The high-temperature (1149 K) treatment of the por-Si surface in acetone vapor favors the formation of a carbonized layer possessing a characteristic photoluminescence spectrum with a maximum intensity at 458 nm. The IR spectra indicate the presence of a silicon carbide phase, identified as the cubic β-SiC, with a characteristic absorption at 800–833 cm⁻¹. A strong shift of the high-frequency wing of the IR absorption spectrum is explained by the carbon substitution for one oxygen in the O-Si-O groups.     

The laser-induced surface evaporation

A special mode of laser action—the surface evaporation—has been experimentally studied on a large number of various materials. Characteristic features of the pure evaporation mode have been established, and some possible applications of the method for modifying surfaces and clean-cutting of biopolymers are indicated.     

High-accuracy optoelectronic transducer for linear displacement based on a CCD and microelectronics

Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1990.     

Smallest flow rate with a specified area of the filtration region

The forms of regions with a fixed area realizing the minimum filtrational flow rate or total heat flux are found.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 52, No. 4, pp. 633–637, April, 1987.