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Cu thin films were grown by sputter deposition on SiO2 substrates with a Cr underlayer that is known to improve the adhesion between Cu and SiO2. The initial stage of Cu growth was investigated using transmission electron microscopy. Results showed that non-wetting spherical Cu nanoislands were formed with a random crystalline orientation on Cr/SiO2, and evolved into a randomly oriented polycrystalline thin film. These results were then compared with our previous results on the initial growth of Cu on SiO2 with and without a Ti underlayer. A quantitative model was proposed to explain the difference in dependence of the wettability of microscopic nanoislands and that of the adhesion of macroscopic thin films on interfacial interactions and surface energies. [ABSTRACT FROM AUTHOR]

The plasmon absorption peak of 31-nm gold particles in aqueous solution was redshifted and broadened by the adsorption of protein. This effect is more striking in the acidic solution than in the alkaline solution. The adsorption is irreversible. When a small amount of protein was added to the colloidal solution, this effect was weak, but a small shoulder emerged at about 680 nm. With increasing quantity of the protein, the effect of the interaction became very strong. The small shoulder became larger and shifted to about 720 nm. But further addition of protein reduced the effect and finally the absorption spectrum became identical with the original colloidal solution. A model is presented which considers two adsorption manners of the protein on gold. Cytochrome b-562 is of cylindrical shape (height is 5.0 nm and diameter is 2.5 nm.) and has the chromophore at the position of about 3.5 nm from the bottom. Consequently, the 'side-on' adsorption manner of the protein on gold which dominates at low concentrations and the 'tail-on' adsorption fashion which dominates at high concentrations cause difference in the interaction distance between the surface plasmon and chromophore. The interaction between gold particles and the protein depends largely on the distance between the gold-particle surface and protoheme IX in the protein. The redshift and broadening of absorption peaks occurred at the side-on adsorption manner. We disclose an initial effort for developing a novel method to determine the configuration of protein adsorbed on colloidal particles. [ABSTRACT FROM AUTHOR]

Bone-resorbing activities of 24-epi-1 alpha-hydroxyvitamin D2 [24-epi-1 alpha(OH)D2], 24-epi-1 alpha,25-dihydroxyvitamin D2 [24-epi-1,25(OH)2D2], and 1 alpha,24S,25-trihydroxyvitamin D2 [1,24S,25(OH)3D2], which might be a metabolite of 24-epi-1,25(OH)2D2, were investigated. In an in vitro bone resorption test, the activity of 24-epi-1 alpha(OH)D2 was similar to that of 1 alpha-hydroxyvitamin D3 [1 alpha(OH)D3] at 10(-9) M-10(-6) M. The activity of 24-epi-1,25(OH)2D2 was weaker than that of 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] at 10(-11) M-10(-8) M. On the other hand, the activity of 1,24S,25(OH)3D2 was similar to that of 24-epi-1,25(OH)2D2 at 10(-11) M-10(-9) M. In the formation assay of osteoclast-like cells, the activity of 24-epi-1 alpha(OH)D2 was weaker than that of 1 alpha(OH)D3 at 10(-7) M. The activity of 24-epi-1,25(OH)2D2 was almost similar to that of 1,25(OH)2D3 at 10(-11) M-10(-7) M. The activity of 1,24S,25(OH)3D2 was significantly weaker than that of 24-epi-1,25(OH)2D2 at 10(-11) M-10(-9) M. In the two experiments, the potencies of 24-epi-1,25(OH)2D2 were about 100 times higher than those of 24-epi-1 alpha(OH)D2. In an in vivo/in vitro bone resorption test, the activity of 24-epi-1 alpha(OH)D2 was almost similar to those of 1 alpha(OH)D3 and 1,25(OH)2D3 and higher than those of 24-epi-1,25(OH)2D2 and 1,24S,25(OH)3D2. 24-epi-1 alpha-(OH)D2 and 1 alpha(OH)D3 were longer lasting than 24-epi-1,25(OH)2D2 and 1,25(OH)2D3 in this experiment.(ABSTRACT TRUNCATED AT 250 WORDS) [ABSTRACT FROM AUTHOR]

Two fluoro analogs of 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3], 24a-homo-24,24-difluoro-1 alpha,25-dihydroxyvitamin D3 [24aF2-homo-1,25(OH)2D3], and 26,27-dimethyl-24,24-difluoro-1 alpha,25-dihydroxyvitamin D3 [24F2-1,25(OH)2(Me)2D3] were examined for calcium (Ca)-regulating activity. The objective of the present study was to determine whether or not fluoro substitution at 24-position would alter activities of the original compounds, that is, 26,27-dimethyl 1 alpha,25-dihydroxyvitamin. D3[1,25(OH)2(Me)2D3] and 24-homo-1 alpha,25-dihydroxyvitamin D3 [24homo-1,25(OH)2D3], respectively. The relative activities of 24aF2-homo-1,25(OH)2D3, 24F2-1,25(OH)2(Me)2D3, and 1,25(OH)2D3 in competing with 1,25(OH)2D3 for binding to chick intestinal cytosol receptor were 0.28:0.5:1.0. The relative potencies of the same series of compounds in competition for the vitamin D-deficient rat serum binding sites were 0.04:0.15:1. Bone-resorbing activities of two fluoro analogs in cultures of neonatal mouse parietal bones were more potent than that of 1,25(OH)2D3. Similar results were recognized in stimulating activities of osteoclast-like cell formation. Responses of two fluoro analogs to intestinal Ca absorption were similar to that of 1,25(OH)2D3. The potencies of 1,25(OH)2D3 and its fluoro analogs in bone Ca mobilization were the highest with 1,25(OH)2D3, followed by 24F2-1,25(OH)2(Me)2D3 and 24aF2-homo-1,25(OH)2D3, in that order. From these results and the data of Paulson et al., fluoro substitution in 24-position of 1,25(OH)2D3 apparently does not alter their activities,hence, the fluoro substitution at 24-position of 1,25(OH)2D3 and the elongation of side chain of 1,25(OH)2D3 may not intensify Ca-regulating activity. [ABSTRACT FROM AUTHOR]

Reports the existence of an extinction temperature in WSi[sub x] film growth from WF[sub 6] and SiH[sub 4]. Indication of domination by radical chain reactions in gas phase; Decrease of deposition rate at an extinction temperature; Use of low pressure chemical vapor deposition.

Examines the deposition of diamond films in the silicon wafer at 135 degree celsius. Use of a filament-assisted chemical vapor deposition; Details on the cooling of silicon wafer substrates; Identification of the films by Raman spectroscopy; Production of the clearly faceted crystals.

Basic photoelectronic properties of hydrogenated amorphous germanium nitride (a-GeNx:H) are presented for the first time. Amorphous-GeNx:H films were prepared by an rf reactive sputtering of a Ge target using Ar+N2+H2 mixed gases and their optical band gaps were controlled continuously in the range from 1.0 to 3.3 eV by varying the compositional ratio of nitrogen to germanium. In contrast to H-free a-GeNx, the temperature dependence of the dark conductivity of a-GeNx:H shows that thermally activated band conduction prevails in the carrier transport over a wide temperature range at least down to 180 K. The photo-to-dark conductivity ratio under AM1 light of unoptimized a-GeNx:H amounts to 40. [ABSTRACT FROM AUTHOR]