Effects of oviducal cells on the survival and fertilizing ability of fowl spermatozoa

The activity of the dissociative anaesthetics ketamine and gamma-hydroxybutyrate against seizures induced by mercaptopropionate and pentylenetetrazol have been determined. Ketamine (90 mg/kg) prevented the seizures induced by both convulsants, but gamma-hydroxybutyrate had negligible anticonvulsant activity. Mercaptopropionate (150 mg/kg) produced a rapid fall in whole brain glutamate decarboxylase activity which correlated with the onset of convulsions. Ketamine given prior to the mercaptopropionate prevented the convulsions, but had no effect on the reduction of enzyme activity. It was concluded that although ketamine was an anticonvulsant it did not act by preventing the inhibition of glutamate decarboxylase responsible for mercaptopropionate-induced convulsions.     

Formation of catalytic CuLaAl11O19/Al2O3composite powder

The solid-state reaction and hydrocarbon-removal activities of composite powders in the system of CuO and La-modified Al2O3 were studied for the purpose of their application to heat-stable catalyst in exhaust-treatment. X-ray diffraction revealed the formation of catalytic nanocomposite-powder of CuLaAl11O19 and -Al2O3 at 1100 °C from the solid-state reaction between -Al2O3, CuO and La2O3. The La-modification of -Al2O3 was effective to maintain the large surface areas of these composite powders. The C6H6 removal activities were compared with practical automotive catalyst in the system of Pt–Ce and -Al2O3. The composite-powder of CuLaAl11O19 and -Al2O3 is active for complete oxidation of benzene and the microstructure is favourable as a powder for catalytic coat-layer.     

Poly(l-lactic acid) short fibers prepared by solvent evaporation using sodium tripolyphosphate

A porous material consisting of biodegradable polymer fibers may be one of the best candidates for implants used in the regeneration of damaged tissue, because it has a continuous pore structure that would allow ingrowth of nutriments, tissues, blood vessels or cells. In the present work, short fibers of biodegradable poly(l-lactic acid) (PLLA) were successfully prepared by the dropwise addition of PLLA dissolved in methylene chloride to a poly(vinyl alcohol) (PVA) solution containing sodium tripolyphosphate with stirring. It was suggested that droplets of the PLLA solution form spheres coated with PVA, which are then deformed into fibrous shapes due to stirring. The length of fibers was 200-800 μm and was controlled by the stirring rate, the PLLA concentration of the droplets and the PVA concentration. A PLLA porous block could be easily prepared by sintering the PLLA fibers at 173 °C for 10 min. The material had a continuous pore structure with the average pore size of approximately 40 μm and porosity of about 80%.     

Tribological Properties of Unidirectionally Aligned Silicon Nitride

A silicon nitride ceramic with unidirectionally aligned β-Si₃N₄ elongated grains (UA-SN) was fabricated by sintering the extruded Si₃N₄ green body with a small amount of rodlike β-Si₃N₄ seed. The effect of anisotropy in microstructure on tribological properties was investigated, compared with a fine-grained Si₃N₄ without seed. Block-on-ring tests without lubricant were conducted at sliding speeds of 0.15 and 1.5 m/s, with a normal load of 5 N and a sliding distance of 75 m, using the UA-SN and Si₃N₄ without seeds as block specimens and commercially supplied Si₃N₄ as ring specimens. For UA-SN, tribological properties were evaluated in three directions with respect to the grain alignment: the plane normal to the grain alignment, and in the direction parallel to or perpendicular to the grain alignment in the side plane. For both sliding speeds, the plane normal to the grain alignment exhibited the highest wear resistance, and the worn surface of this plane was quite smooth, in contrast to the other specimens whose surfaces were irregular owing to grain dropping. It is considered that the high wear resistance achieved in this plane is attributable to the inhibition of crack propagation along the sliding surface by the stacked elongated grains normal to the sliding surface.     

Dye-Sensitized Solar Cells Based on the Principles and Materials of Photosynthesis: Mechanisms of Suppression and Enhancement of Photocurrent and Conversion Efficiency

Attempts have been made to develop dye-sensitized solar cells based on the principles and materials of photosynthesis: We first tested photosynthetic pigments, carotenoids (Cars), chlorophylls (Chls) and their derivatives, to find sensitizers showing reasonable performance (photocurrent and conversion efficiency). We then tried to introduce the principles of photosynthesis, including electron transfer and energy transfer from Car to Phe a. Also, we tried co-sensitization using the pheophorbide (Phe) a and Chl c₂ pair which further enhanced the performance of the component sensitizers as follows: J_sc = 9.0 + 13.8 → 14.0 mA cm⁻² and η = 3.4 + 4.6 → 5.4%.     

Hexagonal boron nitride as a new ultraviolet luminescent material and its application—Fluorescence properties of hBN single-crystal powder

Luminous properties of hexagonal boron nitride (hBN) single-crystal powder were studied by cathodoluminescence and photoluminescence spectroscopy. The single crystals grown by a high pressure and high temperature method showed typical excitonic spectra at peak wavelengths of 215, 220, and 227 nm at room temperature. Well-faceted hexagonal shaped single crystals exhibited the dominant 215-nm band. The 220- and 227-nm bands were singly or concurrently observed in the case of irregular-shaped crystal powders, though no discernible difference between the morphologies of crystal powders showing differently superimposed luminous spectral profiles of the 220- and 227-nm bands was observed. However, each band showed different spectral and decay features at 8 K, implying that the origins of the two bands are different.     

Continuous synthesis of monodispersed silver nanoparticles using a homogeneous heating microwave reactor system

Continuous synthesis of silver nanoparticles based on a polyol process was conducted using a microwave-assisted flow reactor installed in a cylindrical resonance cavity. Silver nitrate (AgNO(3)) and poly(N-vinylpyrrolidone) (PVP) dissolved in ethylene glycol were used respectively as a silver metal precursor and as a capping agent of nanoparticles. Ethylene glycol worked as the solvent and simultaneously as the reductant. Silver nanoparticles of narrow size distributions were synthesized steadily for 5 h, maintaining almost constant yield (>93%) and quality. The reaction was achieved within 2.8 s of residence time, although nanoparticles were not formed under this flow rate by conventional heating. A narrower particle size distribution was realized by the increased flow rate of the reaction solution. Nanoparticles of 9.8 nm average size with a standard deviation of 0.9 nm were synthesized at the rate of 100 ml h(-l).