Effect of titanium,copper and iron on silicon solar cells

The effect of Ti, Cu and Fe on silicon solar cells has been investigated. Ti severely degrades cell performance above a concentration of 10¹¹ cm^?3. The presence of 2 × 10¹⁴ cm^?3 Ti results in a 63% loss in cell performance and more than an order of magnitude reduction in carrier lifetime. Ti gives rise to two deep levels in Si at Ev + 0.30 eV and Ec ? 0.27 eV. Copper, at concentrations below 10¹⁶ cm^?3, has negligible effect on cell performance and carrier lifetime. Above 10¹⁶ cm^?3 copper occasionally produces a 10–15% loss in cell performance with a noticeable increase in junction excess current. No recombination centers were found due to Cu, instead considerable precipitation in the starting material was observed. Fe begins to hurt the cell performance above a concentration of 2 × 10¹⁴ cm^?3. Iron at 1.7 × 10¹⁵ cm^?3 results in 46% loss in cell efficiency and about an order of magnitude reduction in lifetime. Fe induces a deep level in silicon at Ev + 0.4 eV. The active center density, for both Ti and Fe, is only a very small fraction of the total impurity content in the starting silicon wafer.     

Histochemistry of mucosubstances in the mantle of fresh water mussel Parreysia corrugata var. nagpoorensis (Lea). I. Mucosubstances of the inner marginal fold

Formol-calcium acetate-fixed sections of the mantle of Parreysia corrugata var. nagpoorensis (Lea) were subjected to various histochemical reactions for mucosubstances. The results of these reactions on the inner marginal fold indicate that it possesses two types of mucous cells secreting sulphomucins and sialomucins. The sulphated mucus is strongly alcianophilic. Its alcianophilia persists when the tissues are stained with Alcian blue in concentration of up to 0.5 M magnesium chloride. The basal inner epithelial cells of the fold contain glycogen while the remaining cells contain neutral muscosubstances. The role of the mucosubstances with reference to feeding is discussed.     

Genital sex pheromones of ixodid ticks: 1. Evidence of occurrence in anterior reproductive tract of American dog tick,Dermacentor variabilis (Say) (Acari: Ixodidae)

The occurrence of a genital sex pheromone in the anterior reproductive tract of partially fed femaleDermacentor variabilis was demonstrated by extraction and bioassay. A new type of bioassay, the neutered female assay, was developed to test the potency of extracts or chemically defined fractions to stimulate males to copulate. Electrophysiological tests confirmed the ability of males to detect the pheromone with sensilla on their cheliceral digits. Males of bothD. variabilis andD. andersoni exhibited neuronal excitation when stimulated with extracts of theD. variabilis reproductive tissues. The pheromone, which is soluble in methanol, was fractionated and found to contain at least two fractions that stimulated copulation by sexually excited males. Evidently, the pheromone is a mixture of two or more compounds. Histologic, ultrastructural, and histochemical studies suggest the vestibular vagina as the site of genital sex pheromone occurrence, presumably from secretions of the surrounding lobular accessory gland. The identity of the compounds that comprise the pheromone remains unknown.Supported by grants AI10986 and AI10987 from the National Institute of Allergy and Infectious Diseases, National Institute of Health, U.S. Public Health Service, Bethesda, Maryland 20205.     

Sensitivities of ocular tissues to acute pressure-induced ischemia

Intraocular pressure was artificially elevated for eight hours in eight owl monkeys. The first permanent effect (produced at a perfusion pressure of plus 15 mm Hg) was partial necrosis of iris stroma and ciliary processes, associated with microscopic lesions in the photoreceptors and retina pigment epithelium around the disc and in the retinal periphery. At a slightly higher pressure, visual nerve fibers in the retina and optic nerve and their ganglion cells were affected. Simultaneously, the outer retinal layers showed damage to the pigment epithelium, photoreceptors, and other nuclear layers. At even higher pressures, nearly all the other intraocular tissues were affected except for Müller cells, astroglia in the optic nerve head, epithelium of the pars plana, and the pigment cells of the choroid. The possibility is raised of a nonischemic pressure-induced mechanism for destruction of disc astrocytes in human chronic glaucoma.     

Reduction operations for constraint satisfaction

The problem of labeling a set of units in such a way as to satisfy an order-N compatibility relation is discussed and shown to be NP-complete. Some general procedures for reducing size of the compatibility relation are defined, properties of these procedures are derived, and their incorporation into a backtracking process is discussed. Their computational cost and storage requirements are also considered.     

Myopathy in guinea pigs

Myopathy resembling nutritional muscular dystrophy occurred in a colony of 150 guinea pigs. Of 54 animals affected, 27 died. Major clinical signs were depression, conjunctivitis, and reluctance to move. Lesions were widespread throughout skeletal and cardiac musculature. Clinical signs and deaths ceased when the diet was changed to a different commercial ration. A single intramuscular injection of sodium selenite and alphatocopherol brought prompt remission of clinical signs in one group of 20 so treated.     

Effectiveness of catalytic archipelagos—II: Random arrays of random islands

Voronoi polygons are used to simulate a random distribution of irregularly shaped catalytic islands. Finite element mathematics is used to determine the catalytic effectiveness of the islands when adsorbed reactants diffuse and disappear by a first order reaction at their boundaries. It is found that the catalytic effectiveness of the islands at any fractional coverage can be estimated reasonably accurately either from asymptotic formulae, valid for certain values of diffusion, adsorption, and reaction constants, or from the equivalent annulus approximation found earlier to be accurate for certain regular arrays of regular islands. The equivalent annulus approximation allows analytic prediction of the catalytic effectiveness for any set of parameter conditions given only the fraction area ratio Γ/Ω. Both of these quantities of which can be determined directly from a photomicrog of a representative sample.