Determination of the major urinary metabolite of diphenylhydantoin by high-performance liquid chromatography

A method is described for the determination of 5-(p-hydroxyphenyl)-5-phenylhydantoin (p-HPPH), a major urinary metabolite of 5,5-diphenylhydantoin (DPH) in man. The assay involves acid hydrolysis, extraction and high-performance liquid chromatographic analysis using a column comprised of small-particle silica gel. This procedure has been used to determine p-HPPH levels in urine from healthy volunteers who ingested 400 mg of sodium DPH. The p-HPPH concentration was found to range from 10 to 300 μg/ml. The minimum detectable concentration of urinary p-HPPH was 1 μg/ml.     

OBSERVATION OF PHASE TRANSITIONS IN INTACT LEAVES BY INTRINSIC LOW-LEVEL CHEMILUMINESCENCE

The Arrhenius plots of a remnant intrinsic ultraweak light emission from dark-adapted leaves of hibiscus, bean, cucumber, tomato and spinach exhibit strong linear behavior, despite the structural heterogeneity of the intact leaf. Well-defined break points within the temperature range from 8°C to 17°C could be found in these plant species. In the case of hibiscus and cucumber an additional feature of a thermotropic phase change around 20°C and 24°C, respectively, could be detected. However, in the case of spinach, a representative of a chilling resistant plant species, the changes in activation energies obtained were only minor. Isolated chloroplasts of spinach leaves did not show identical thermal behavior of luminescence in comparison with the intact leaf. The activation energies were significantly lower and the transition features were different compared to intact leaves. A possible relationship between the thermal behavior of low-level chemiluminescence and the chilling sensitivity of plants is suggested.     

Development and application of an eco-hydrodynamic model for radionuclides in a brackish lake: Case study of Lake Obuchi, Japan, bordered by nuclear fuel cycling facilities</p> </p>

Summary In order to evaluate the transport of ³H and ¹³⁷Cs radionuclides in semi-closed brackish Lake Obuchi, Japan, bordered by nuclear fuel cycling facilities, a 3D-lower-trophic eco-hydrodynamic model has been developed and validated. In a short-term prediction, ³H and ¹³⁷Cs activity levels in water should be in an agreement with field measurements. It became clear that the results depended on the mixing of fresh water and seawater in the model. Moreover, a short-term simulation estimated that most ³H and ¹³⁷Cs flowed to the ocean rather than remaining in the lake. Based on calculations over the past 50 years, a peak of ¹³⁷Cs in sediment was in 1963, when the maximum ¹³⁷Cs fallout was observed. The calculation showed a rapid decrease after that peak, however, the field measurement data gradually declined. This suggested that the process by which ¹³⁷Cs accumulated from the watershed to the lake was actually slower in the field than in the model calculations. The model may be successfully applied to a variety of different environmental situations as a generic tool for evaluating the concentration and migration of ³H and ¹³⁷Cs in a brackish lake.</p> </p>     

Reduction of isocyanates and carbodiimides via hydrosilylation

The hydrosilylation of isocyanates is promoted by palladium catalysts and affords N-silylformamides or C-silylamides. The orientation of the reaction depended upon the structure of isocyanates. The reaction of carbodiimides with silicon hydrides, catalyzed by PdCl₂ or (Ph₃P)₃RhCl, required higher temperatures to give N-silylformamidines. The adducts obtained in these reactions are precursors to formamides, formamidines, and their N-acetyl derivatives.     

Unusual Gruneisen and Bridgman parameters of low-density amorphous ice and their implications on pressure induced amorphization

The low-temperature limiting value of the Grüneisen parameter for low-frequency phonons and the density dependence of the thermal conductivity (Bridgman parameter) of low-density amorphous (LDA) ice, high-density amorphous (HDA) ice, hexagonal ice Ih, and cubic ice Ic were calculated from high-pressure sound velocity and thermal conductivity measurements, yielding negative values for all states except HDA ice. LDA ice is the first amorphous state to exhibit a negative Bridgman parameter, and negative Grüneisen parameters are relatively unusual. Since Ih, Ic, and LDA ice all transform to HDA upon pressurization at low temperatures and share the unusual feature of negative Grüneisen parameters, this seems to be a prerequisite for pressure induced amorphization. We estimate that the Grüneisen parameter increases at the ice Ih to XI transition, and may become positive in ice XI, which indicates that proton-ordered ice XI does not amorphize like ice Ih on pressurization.     

Speciation of aluminum in soil extracts using cation and anion exchangers followed by a flow-injection system with fluorescence detection using lumogallion.

Flow-injection analysis (FIA) with fluorescence detection of aluminum using lumogallion was applied to the chemical speciation of aluminum in soil extracts after the separation of aluminum species with ionic exchangers. Aluminum complexes with organic substances (anion species) can be specified from other species by using a strongly acidic cation exchanger in the pH range of 3 to 5. Furthermore, aluminum can be separated into three categories, namely, (i) the Al3+ and Al-OH complex, (ii) aluminum organic complexes (cation species), and (iii) its anion species by using a strongly acidic and a weakly acidic cation exchanger at around pH 5. A considerable percentage of water-soluble aluminum in soils was found to be complexes with humic substances.     

Transfer of 137Cs and stable Cs in soil-grass-milk pathway in Aomori, Japan

The soil-to-grass transfer factors and grass-to-milk transfer coefficients were determined for ¹³⁷Cs and stable Cs in soil, grass and milk samples collected in Aomori Prefecture, Japan. The concentrations of ¹³⁷Cs in the soil and grass samples collected from 25 sampling sites were 13±12 Bq.kg^-1 and 2.0±2.1 Bq.kg^-1 dry wt., respectively. The geometric mean of soil-to-grass transfer factor of ¹³⁷Cs was 0.13 and its 95% confidence interval was 0.017-0.98. The transfer factor of ¹³⁷Cs was higher than that of stable Cs, and they had a positive correlation. The concentration of K in the soil affected both transfer factors. The concentration of ¹³⁷Cs in milk samples collected from 16 sites was 76±43 mBq.kg^-1 fresh wt. and had a good correlation with that of stable Cs. The geometric mean of grass-to-milk transfer coefficient of ¹³⁷Cs was 0.0027, assuming that a cow's total daily intake was 20 kg of dry grass. The transfer coefficient of ¹³⁷Cs was positively correlated with that of stable Cs.     

Differential preconcentration of arsenic(III) and arsenic(V) with thionalide loaded on silica gel

2-Mercapto-N-2-naphtylacetamide (thionalide) on silica gel is used for differential preconcentration of μg l^?1 levels of arsenic(III) and arsenic(V) from aqueous solution. In batch experiments, arsenic(III) was quantitatively retained on the gel from solutions of pH 6.5–8.5, but arsenic(V) and organic arsenic compounds were not retained. The chelating capacity of the gel was 5.6 μmol g^?1 As(III) at pH 7.0. Arsenic retained on teh column was completely eluted with 25 ml of 0.01 M sodium borate in 0.01 M sodium hydroxide containing 10 mg l^?1 iodine (pH 10). The arsenic was determined by silver diethyldithiocarbamate spectrophotometry. Arsenic(V) was subsequently determined after reduction to arsenic(III) with sulphite and iodide. Arsenic(III) and arsenic(V) in sea water are shown to be < 0.12 and 1.6 μg l^?1, respectively.     

Determination of molecular weight distribution for polypropylene by column fractionation and gel-permeation chromatography

Investigations on the molecular weight distribution of cyrstalline polypropylene were carried out by column fractionation and gel-permeation chromatography for the purpose of comparing the determination methods. Average molecular weight, standard deviation, skewness, and kurtosis were calculated as statistical parameters from the distribution curve of each, and the number-average and weight-average molecular weights were determined by osmometry and light scattering. The molecular weight distribution curves obtained from column fractionation were found to be narrower than those from gel-permeation chromatography, and it was confirmed that the molecular weight distribution curve obtained from GPC was more accurate and reliable than that from column fractionation by the fact that the average molecular weight from GPC agreed fairly well with that from the absolute methods. On the other hand, no clear difference between these determination methods was observed with respect to skewness and kurtosis of the data, while the standard deviation from GPC seemed to be greater than that from column fractionation.     

Fischer-Tropsch synthesis over Ru/Al2O3 catalysts

Fischer-Tropsch syntheses (FTS) were carried out in a slurry phase over Ru/Al₂O₃ catalysts using hexadecane as a solvent. The outcome of the FTS was dependent on the oxide support, calcination temperature, synthesis gas composition and sulfur content. The addition of Mn/Na to Ru/Al₂O₃ was effective in raising the initial activity and C5+ selectivity, but after 20 hours, the performance of the modified catalyst was similar to that of the unmodified catalyst. An additional investigation involving the use of fresh vs used catalysts demonstrated that an agglomeration of the metallic Ru, at least in part, does occur during the reaction.