Occurrence and determination of a herbicide benthiocarb in rivers and agricultural drainages

The occurrence and determination of a herbicide, benthiocarb, 4-chlorobenzyl N,N-diethylthiolcarbamate (Saturn^®) in rivers and agricultural drainages was investigated. Benthiocarb residues were detected in water samples when it has been applied to rice paddies, after rice seedling transplantation, in concentrations of between 10.00 and 0.11 μg/l. These residues entered into rivers and agricultural drainages as a result of overflows from rice paddies. However, benthiocarb residues could not be found in water samples after the termination of its application to rice paddies, suggesting that the applied benthiocarb might be degraded by microbial and physico-chemical actions such as photochemical reactions occurring on the soil surface. Benthiocarb residue levels were higher in longer rivers than in agricultural drainage. The contribution of rainfall to the benthiocarb concentrations was shown. Benthiocarb in water was extracted with n-hexane and identified by a gas chromatography using a flame photometric detector (sulphur filter 394 nm) and a combined gas chromatography-mass spectrometry-computer system. The minimum detectable amount of benthiocarb in water sample by gas chromatography was 0.56 ng and about 100 ng of benthiocarb could be identified by a gas chromatography-mass spectrometry-computer system.     

Structural analysis of an N-glycan with "beta1-4 bisecting branch" from human serum IgG by negative-ion MSn spectral matching and exoglycosidase digestion

A novel N-linked oligosaccharide (N-glycan) with "beta1-4 bisecting branch (galactose beta1-4 bisecting N-acetylglucosamine)" was found in human serum IgG. Its structure was efficiently analyzed by using beta-galactosidase digestion, a MSn spectral library database, and negative-ion MS2 spectral matching. For confirmation, the novel N-glycan was synthesized by using an expected standard N-glycan (acceptor), UDP-galactose (donor), and beta1-4 galactosyltransferase. This work also demonstrates that the MSn spectral library database, in particular, negative-ion MS2 spectral matching, can efficiently reduce the number of specific, sequential exoglycosidase digestions required and is useful for rapid structural analysis of unknown glycans not in the database.     

Simultaneous analysis of 2-aminopyridine-derivatized neutral and sialylated oligosaccharides from human serum in the negative-ion mode by sonic spray ionization ion trap mass spectrometry

Neutral and acidic (sialylated) 2-aminopyridine-derivatized (PA) oligosaccharides were analyzed by using reversed-phase high-performance liquid chromatography/ion trap mass spectrometry (RP-HPLC/IT MS) with a sonic spray ionization (SSI) source. Under the RP-HPLC separation using a buffer of 1 mM ammonium acetate (pH4.3) at a flow rate of 0.2 mL/min, both PA-oligosaccharides in the negative-ion mode showed a comparable degree of ionization efficiency, differing from that of the positive-ion mode, which exhibits a wide gap between their ionization efficiencies. In addition, the ion intensities of both PA-oligosaccharides were higher in the negative-ion mode than in the positive-ion mode. These results strongly suggest that the negative-ion mode of SSI-MS is suitable for simultaneous analysis of neutral and acidic (sialylated) oligosaccharides in RP-HPLC/MS. In the present study, RP-HPLC/SSI-IT MS in the negative-ion mode was used in the analysis of PA-oligosaccharides from human serum and its usefulness was investigated. As a result, 32 neutral and sialylated PA-oligosaccharides from human serum were identified with differentiating isomeric oligosaccharides and relatively quantified by a single HPLC/MS run. This method is useful for simple and rapid analysis of the overall distribution of neutral and sialylated oligosaccharides in a complex sample such as serum.     

Full-field optical coherence tomography by achromatic phase shifting with a rotating polarizer

We demonstrate two-dimensional detection optical coherence tomography (OCT) using achromatic phase shifting with a rotating polarizer. This phase shifting, which experiences a light beam with a cyclic change in its polarization state, is, in principle, independent of wavelength. We simulated the wavelength dependence of an achromatic phase shifter using Jones calculus and found that the achromatic region exceeded 145 nm when the deviation of the phase retardation was less than +/- 0.5 degrees. Using the achromatic phase shifter and a conventional phase-shift calculation method, we obtained en face OCT images of an onion at different depths. This method is effective to enhance the quality of OCT with an ultrabroad-spectrum light source.     

Dependence of reconstructed image characteristics on the observation condition in light-in-flight recording by holography

We analyze the dependence of the reconstructed image characteristic on the observation condition in the light-in-flight recording by holography both theoretically and experimentally. This holography makes it possible to record a propagating light pulse. We have found that the shape of the reconstructed image is changed when the observation position is vertically moved along the hologram plane. The reconstructed image is numerically simulated on the basis of the theory and is experimentally obtained by using a 373 fs pulsed laser. The numerical results agree with the experimental result, and the validity of the theory is verified. Also, experimental results are analyzed and the restoration of the reconstructed image is discussed.     

Fractional power approximations of elliptic integrals and bessel functions

In the previous papers [1][3], fractional powers were used to approximate elementary functions and their usefulness was proved with experimental results. In the present paper, some further investigations are reported. That is, elliptic integrals in Legendre's canonical form and Bessel functions are approximated by fractional powers. As the fractional power approximation,

f(x) c₀ + c₁x + c₂x^p

is discussed. When all coefficients c₀, c₁, c₂, p are properly assigned, the accuracy of this approximation becomes comparable to that of the Chebyshev approximation using polynomials up to the third degree.     

Behaviour of HCH (1,2,3,4,5,6-hexachlorocyclohexane) residue in the aquatic environment

The monthly variation in HCH (1,2,3,4,5,6-hexachlorocyclohexane) residue levels in surface waters was investigated. The logarithms of monthly HCH concentrations described the wave, and the equation of the wave was calculated by the least squares method. The waves indicated maximum concentrations in summer and minimum concentrations in winter at each sampling site. The maximum concentration of HCH in each year decreased gradually. The amplitude of the wave at the reservoir was the smallest among sampling sites. The slope of the wave at the downstream sampling site was smaller than that at the upper stream. Maximum concentration of total HCH at each sampling site in 1985 is estimated from the equations; the concentrations at the upper streams will be about a thousandth or a hundredth of that at the downstreams. Also, the equations for β-and γ-HCH were calculated, and indicated that β-HCH was more persistent than γ-HCH in surface water. The ratio of β-HCH to total HCH in surface water is estimated to be about 60% in 1985.     

A kinetic study of nonoxidative dissolution of galena in aqueous acid solution

This paper presents the results obtained through a kinetic study of the nonoxidative dissolution of natural galena in hydrochloric acid and perchloric acid solutions with and without the addition of sodium chloride. Under the experimental conditions employed in this study, the dissolution rates were controlled by a chemical reaction on the surface of the galena sample. The galena dissolution rate is of the first order with respect to hydrochloric ion activity in hydrochloric acid and perchloric acid solutions. The addition of sodium chloride to the acid solutions greatly enhanced the dissolution rate. The effect of sodium chloride has two possible interpretations: First, it may be the result of an increase in hydrogen ion activity. Second, the enhancement of the dissolution rate observable at high sodium chloride concentration may be due to the specific adsorption of chloride ions or the surface complexing of chloride ions on the galena surface.     

Preparation and properties of fine hematite powders by hydrolysis of iron carboxylate solutions

Submicrometer, crystalline hematite (α-Fe₂O₃) particles were prepared by hydrolysis of organic iron carboxylate solutions using water at 175 °C for 30 minutes. The particle size of hematite was significantly dependent on the liquid-phase stirring speed and the organic compositions. The precipitation rate of hematite from the organic solution followed first-order kinetics. The precipitation rate increased markedly with increasing temperature, and the activation energy for the process was 94.6 kJ mol⁻¹. At 220 °C, the hydrolysis of iron carboxylate solution led to a mixture of hematite and magnetite (Fe₃O₄). The iron oxides prepared at 175 °C to 220 °C were found to be free from organic contamination by the starting material.     

Reaction Sintering of Polycarbosilane-Impregnated Compact of Silicon Carbide Hollow Particles and the Resultant Thermoelectric Properties

Porous SiC ceramics fabricated from hollow particles and polycarbosilane (PSC) are promising materials for high-temperature thermoelectric energy conversion. Reaction sintering of PCS-impregnated compacts of SiC hollow particles gave rise to porous microstructures with the hollow shape remaining. The repetition of the PCS-impregnation and sintering process resulted in only a slight increase in density but in a great improvement in thermoelectric properties.