Assay of Angiotensin I-converting Enzyme-inhibiting Activity Based on the Detection of 3-Hydroxybutyrate with Water-soluble Tetrazolium Salt.

A newly synthesized substrate, 3-hydroxybutyrylglycyl-glycyl-glycine (3HB-GGG), was applied to the assay of ACE-inhibiting activity to overcome the smaller selectivity and sensitivity of the conventional method. In this study, an ACE-inhibiting assay was improved by the use of a water-soluble tetrazolium salt, 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate sodium salt (WST-1), for the detection of 3-hydroxybutyrate, derived from 3HB-GGG. The optimized conditions were as follows: 0.333 mM NAD(+), 0.333 mM WST-1, 0.1 mM EDTA, 0.633 U ml(-1) diaphorase, and 0.700 U ml(-1) 3-hydroxybutyrate dehydrogenase. The developed assay was efficiently applicable to evaluate the ACE-inhibiting activity of practical ACE inhibitors.     

Determination of benzophenones in river-water samples using drop-based liquid phase microextraction coupled with gas chromatography/mass spectrometry.

In this study, a fast, simple and highly sensitive method that employs liquid phase microextraction (LPME)-GC/MS was developed to analyze trace benzophenones (BPs) in river-water samples. The tip of a 10-microl microsyringe filled with toluene (3 microl) was inserted into 2 ml of a river-water sample, and fixed at 5 mm below the water surface of the sample. A toluene droplet was made on the tip of the syringe, and extraction was conducted while agitating at 500 rpm for 15 min. After extraction, 2.0 microl of the extract was put into the syringe again, and directly introduced to GC/MS. The limits of detection (S/N = 3) and quantification (S/N >10) of BPs were 10 and 50 pg ml(-1), respectively. The results of a recovery test ranged over 93.3 - 101.1% (RSD, less than 10%; n = 6). The results of BPs determinations in the river-water samples showed that BPs (ND - 68.9 pg ml(-1)) were detected.     

Liquid chromatographic determination of dimethadione and trimethadione in human serum on octadecyl treated microporous glass columns

Summary The liquid chromatographic determination of trimethadione (TMO) and its methabolite, dimethadione (DMO) were studied by high-performance liquid chromatography (HPLC) on octadecyl-modified microporous glasses, prepared with toluene solution containing octadecyl-dimethylchlorosilane, using two types of microporous glass with various mean pore diameters and/or specific surface areas. Using acetonitrile-water mixtures as eluents, TMO and DMO in human serum were separated on the glasses studied, but with different degrees of resolution. In this present study, we report the development of a rapid and selective HPLC method for the simultaneous analysis of TMO and DMO in human serum.     

Thermal decomposition of propane in shock waves

The thermal decomposition of propane was studied behind reflected shock waves over the temperature range 1100–1450 K and the pressure range 1.5–2.6 atm, by both monitoring the time variations of absorption at 3.39 μm and analyzing the concentrations of the reacted gas mixtures. The rate constants of the elementary reactions were discussed from the results. The rate constant expressions, k₁ = 1.1 × 10¹⁶ exp (?84 kcal/RT) s^?1 and k₄ = 9.3 × 10¹³ exp(?8 kcal/RT) cm³ mol^?1 s^?1, of reactions C₃H₈ → CH₃ + C₂H₅ and C₃H₈ + H → n-C₃H₇ + H₂ were evaluated, respectively.     

Synthesis and properties of the [2.2]paracyclophane‐containing conjugated polymer with benzothiadiazole as an electron acceptor

A novel donor–acceptor type conjugated polymer based on PPE with [2.2]paracyclophane and benzothiadiazole units in the main chain was synthesized by the Sonogashira coupling reaction. The obtained polymer was quite soluble in common organic solvents, and the transparent and uniform thin film of the polymer was obtained easily by casting or spin‐coating from a toluene solution. The polymer showed an extension of π‐delocalization via the through‐space with π‐π stacking according to the UV–visible (UV–vis) absorption spectra in comparison with that of the model compound. The polymer exhibited orange photoluminescence in solution (fluorescence quantum efficiency = 0.13) and in the solid state. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5891–5899, 2004     

A simple and portable colorimeter using a red-green-blue light-emitting diode and its application to the on-site determination of nitrite and iron in river-water.

A portable colorimeter using a red-green-blue light-emitting diode as a light source has been developed. An embedded controller sequentially turns emitters on and off, and acquires the signals detected by two photo diodes synchronized with their blinking. The controller calculates the absorbance and displays it on a liquid-crystal display. The whole system, including a 006P dry cell, is contained in a 100 x 70 x 50 mm aluminum case and its mass is 280 g. This colorimeter was successfully applied to the on-site determination of nitrite and iron in river-water.     

X-ray diffraction investigation of the hexagonal-fcc structural transition in yttrium trihydride under hydrostatic pressure

Pressure induced structural transition of yttrium hydride has been investigated using synchrotron radiation X-ray diffraction measurement up to 24 GPa at room temperature. A reversible hexagonal-fcc transition with a wide intermediate region from 11 to 20 GPa is confirmed, which is consistent with previously reported X-ray results. The diffraction patterns measured for the intermediate state are not interpreted in terms of a hexagonal-fcc coexisting state or as rare-earth structures with various metal-layer stacking sequences. The equation of state determined for the hexagonal-YH₃ provides a bulk modulus B₀ of 71.9 GPa, which is nearly half of the previously reported value, but is within the range of values reported for other rare-earth metal trihydrides with hexagonal structures.     

High temperature pyrolysis of formaldehyde in shock waves

Thermal decomposition of formaldehyde diluted with Ar was studied behind reflected shock waves in the temperature range of 1200–2000 K at total pressures between 1.3 and 3.0 atm. The study was carried out for compositions from the concentrated mixture, 4% CH₂O, to the highly dilute mixture, 0.01% CH₂O by using time-resolve IR-laser absorption and IR-emission, and a single-pulse technique. From a computer-simulation study, the mechanism and the rate-constant expressions that could explain all of our data and previously reported ARAS data were discussed. This data obtained over a wide concentration range from 50 ppm CH₂O to 4% CH₂O were satisfactorily modeled by a five-reaction mechanism. © 1993 John Wiley & Sons, Inc.     

Thermal decomposition of propyne and allene in shock waves

Propyne (p-C₃H₄) or allene (a-C₃H₄) mixtures, highly diluted with Ar, were heated to the temperature range 1200–1570 K at pressures of 1.7–2.6 atm behind reflected shock waves. The thermal decompositions of propyne and allene were studied by both measuring the profiles of the IR emission at 3.48 μm or 5.18 μm and analyzing the concentrations of reacted gas mixtures. The mechanism and the rate constant expressions were discussed from both the profiles and the concentrations of reactant and products obtained. The rate constant expressions for reactions, (1) p-C₃H₄ → a-C₃H₄, (?1) a-C₃H₄ → p-C₃H₄, and (5) p-C₃H₄ + H → CH₃ + C₂H₂ were evaluated.