Numerical analysis of fatigue striations

A computational model was developed to numerically analyse fatigue striations. The inclined strip yield model with continuous distributions of infinitesimal dislocations was utilized to express the crack tip plasticity in this model. The fatigue crack tip blunting process was approximated by sequential activation of two slip lines under loading, and crack closure during unloading was taken into account. The plastic zone at a growing fatigue crack tip at the maximum load was independent of the crack growth up to ten cycles while the reversed plastic zone decreased in a size to one twentieth of that at the maximum load as the crack grew. The ratio of these plastic zone sizes and also the crack tip opening displacement were quite different from the simple prediction by J.R. Rice for a stationary crack. The computed striation spacings were compared with the observed ones and moderate agreement between them obtained.     

All-solid-state high-power conduction-cooled Nd:YLF rod laser

A high-average-power conduction-cooled diode-pumped Nd:YLF rod laser has been developed. A new conduction-cooled side-pumping scheme with a solid prismatic pump-light confinement cavity was employed. A transparent, high-thermal-conductivity MgF>(2) prism was used as a highly efficient pump cavity as well as a low-thermal-resistance heat spreader. The pumping efficiency and thermal resistance of the cavity were 85% and 0.20 degrees C degrees W, respectively. When this scheme was combined with heat pipes for heat removal, a maximum average output power of 72 W was demonstrated, with an optical slope efficiency as high as 49%.     

Application of the N2 laser to laser microprobe spectrochemical analysis

Results are presented of a study on the application of a N₂ laser to the spectrochemical analysis of microareas. It is found that when the pressure of the surrounding gas is reduced to 1 Torr (133 Pa) or thereabouts, the plasma induced by the bombardment of N₂ laser light yields sharp atomic line spectra with a negligibly low background signal, facilitating quantitative analysis with reasonable precision. A simple and rapid detection method is employed in which the atomic emission spectrum from the plasma produced under successive bombardment (10 Hz) is recorded directly on a chart by means of scanning the wavelength of a monochromator. By using iron-steel standard samples of known content, it is demonstrated that a plot of the intensity of the 425.4 nm emission line of Cr against the Cr content shows a linear relationship.     

The Change of the Structure of Amylose During the Inclusion of 2-Naphthol in Sealed-heating Process

When a mixture of linear amylose (AS200) and2-naphthol was heated in a glass ampoule above60 ^circC, an inclusion compound was formed. Theinclusion formation accompanied the structural changeof AS200 from a 6₁-helix to a 7₁-helix. Fromthe UV determination, one 2-naphthol molecule could beincluded per one 7₁-helical turn of amylose. It was found that the heating temperature, heating timeand water content in the physical mixture wereimportant parameters affecting the formation ofinclusion compounds during sealed-heating.     

Thomson-scattering diagnostics of Kr/Ne and Kr/He plasmas using a picosecond laser

Thomson scattering from plasmas in high-pressure discharges for rare-gas-halide excimer-laser pumping was observed using a frequency-doubled 300 ps Nd: YAG laser. A temporal resolution of 1 ns was realized for the Thomson-scattering measurement, and detailed temporal changes of the electron density and temperature were measured in Kr/Ne and Kr/He plasmas. Calculations using a computer simulation showed good agreement with the experimental results, implying that the plasma dynamics is properly treated in the simulation.     

Selective high-performance liquid chromatographic method for the determination of glycyrrhizin and glycyrrhetic acid-3-O-glucuronide in biological fluids: application of ion-pair extraction and fluorescence labelling agent

A selective high-performance liquid chromatographic method has been developed for the simultaneous determination of glycyrrhizin and glycyrrhetic acid-3-O-glucuronide in biological fluids of the rat. The procedure is based on the ion-pair formation using tetra-n-amylammonium bromide, extraction with ethyl acetate-n-heptane from the salt-saturated aqueous phase, labelling with 4-bromomethyl-7-methoxycoumarin, followed by chromatographic separation with fluorescence detection. Glycyrrhizin in plasma, bile and urine could be precisely determined in concentrations as low as 1, 1 and 2.5 micrograms/ml, respectively, in a 0.1-ml sample. The equivalent values for the glucuronide were 1, 2.5 and 2.5 micrograms/ml, respectively. The method is applicable in pharmacokinetic studies of glycyrrhizin in small animals.     

Improvement in appearance of colors for elderly persons using lightness transform

The color of an object appears to be different for elderly and young persons. This is because human visual features vary with on age. In general, the spectral transmittance of the crystalline lens of an elderly person is lower than that of a young person. The low spectral transmittance decreases the brightness of the visual field. This phenomenon affects the color appearance of an image in human visual perception. In this paper, a lightness transform method is proposed to improve the color appearance of images for elderly persons. In the proposed method, colors that are difficult for an elderly person to see are transformed into colors that are easy to see by adding lightness contrast. The performance of the proposed method is confirmed in experiments using digital images.     

Determination of nitrocatecholamines in rat brain using high-performance liquid chromatography-peroxyoxalate chemiluminescence reaction detection

We have developed a method to determine nitrocatecholamines (nitroCAs: nitronorepinephrine (nitroNE), nitroepinephrine (nitroE), and nitrodopamine (nitroDA)) in rat brain using high-performance liquid chromatography-peroxyoxalate chemiluminescence (POCL) reaction detection. This method consists of in-line extraction of amines, including nitroCAs, followed by separation on an ODS column, reduction of nitroCAs with a reducer column, derivatization with ethylenediamine, and finally the POCL reaction detection. Use of the reducer column increased the sensitivity of detection of nitroCAs by 45-172%. The limits of detection (signal-to-noise ratio of 3) were 75fmol for nitroNE, 125fmol for nitroE, and 150fmol for nitroDA. By using this method, not only nitroNE, but nitroE and nitroDA were determined in rat brain. The concentrations of nitroNE and nitroE in rat brain were 9.2+/-2.0 and 13.5+/-2.5 pmol/g tissue, respectively (n=5).     

On the mechanism of carbon nanotube formation: the role of the catalyst

This work examines the recent developments in non-traditional catalyst-assisted chemical vapour deposition of carbon nanotubes (CNTs) with a view to determining the essential role of the catalyst in nanotube growth. A brief overview of the techniques reliant on the structural reorganization of carbon to form CNTs is provided. Additionally, CNT synthesis methods based upon ceramic, noble metal, and semiconducting nanoparticle catalysts are presented. Experimental evidence is provided for CNT growth using noble metal and semiconducting nanoparticle catalysts. A model for CNT growth consistent with the experimental results is proposed, in which the structural reorganization of carbon to form CNTs is paramount.     

Large-Scale Production of Phospholipase D from Streptomyces racemochromogenes and Its Application to Soybean Lecithin Modification

Phospholipase D (PLD) catalyzes transphosphatidylation, causing inter-conversion of the polar head group of phospholipids and phospholipid hydrolysis. Previously, we cloned PLD103, a PLD with high transphosphatidylation activity, from Streptomyces racemochromogenes strain 10-3. Here, we report the construction of an expression system for the PLD103 gene using Streptomyces lividans as the host bacterium to achieve large-scale production. The phosphatidylcholine (PC) hydrolysis activity of S. lividans transformed with the expression plasmid containing the PLD103 gene was approximately 90-fold higher than that of the original strain. The recombinant PLD103 (rPLD103) found in the supernatant of the transformant culture medium was close to homogeneous. The rPLD103 was indistinguishable from the native enzyme in molecular mass and enzymatic properties. Additionally, rPLD103 had high transphosphatidylation activity on PC as a substrate in a simple aqueous one-phase reaction system and was able to modify the phospholipid content of soybean lecithin. Consequently, the expression system produces a stable supply of PLD, which can then be used in the production of phosphatidyl derivatives from lecithin.