Destructive and non-destructive determination of titanium in yttrium,niobium and tantalum oxides by photon activation

Destructive and non-destructive procedures have been developed for the determination of titanium by photon activation analysis. The non-destructive analyses with an internal standard method are performed on niobium and tantalum oxides while destructive determinations, including non-isotope addition and radiochemical separation, are applied to yttrium oxide samples.     

Trapping effect of eugenol on hydroxyl radicals induced by L-DOPA in vitro

Many researchers have stated that eugenol might inhibit lipid peroxidation at the stage of initiation, propagation, or both, and many attempts have been made to elucidate the mechanism of its antioxidant activity. Nevertheless, details of its mechanism are still obscure. This study was carried out to investigate the trapping effect of eugenol on hydroxyl radical generated from L-3,4-dihydroxyphenylalanine (DOPA) in MiliQ water and the generation mechanism of the hydroxyl radical by this system which uses no metallic factor. This was studied by adding L-DOPA and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) to phosphate buffered saline (PBS) or MiliQ water, and the generation of hydroxyl radical was detected on an ESR spectrum. By this method, the effect of antioxidants was detected as a modification of ESR spectra. We found that the eugenol trapped hydroxyl radicals directly, because it had no iron chelating action, did not trap L-DOPA semiquinone radical and inhibited hydroxyl radicals with or without iron ion.     

Microchip-based immunoassay system with branching multichannels for simultaneous determination of interferon-gamma

A bead-bed immunoassay system suitable for simultaneous assay of multiple samples was constructed on a microchip. The chip had branching multichannels and four reaction and detection regions; the constructed system could process four samples at a time with only one pump unit. Interferon gamma was assayed by a 3-step sandwich immunoassay with the system coupled to a thermal lens microscope as a detector. The biases of the signal intensities obtained from each channel were within 10%, and coefficients of variation were almost the same level as the single straight channel assay. The assay time for four samples was 50 min instead of 35 min for one sample in the single-channel assay; hence higher throughput was realized with the branching structure chip.     

Aqueous phase behavior of a 1-O-phytanyl-beta-D-xyloside/water system. Glycolipid-based bicontinuous cubic phases of crystallographic space groups Pn3m and Ia3d

Temperature- and concentration-dependent aqueous phase diagram of a novel alkylglycoside, 1-O-phytanyl-beta-D-xyloside (beta-Xyl(Phyt)), was studied using small-angle X-ray scattering, polarizing optical microscopy, and differential scanning calorimetry. The phases found in this system include an Lc phase, an Lalpha phase, an HII phase, two inverted cubic phases of crystallographic space groups Pn3m and Ia3d, and a fluid isotropic phase, FI. The phase diagram of the beta-Xyl(Phyt)/water system is similar to that for the 1-monooleylglycerol (MO)/water system, suggesting that the phase behavior is largely determined by the overall molecular shape rather than the details of surfactant molecular structure. Moreover, the structural parameters of the beta-Xyl(Phyt) liquid crystals are also similar to those of the MO/water, due primarily to the similar molecular dimensions of two molecules. As compared to the MO/water system, however, the beta-Xyl(Phyt)/water system displays a lower value of TK ( approximately 8.(5) degrees C) and a wider temperature window for the mesophases (8.(5)-120 degrees C). Moreover, beta-Xyl(Phyt) is chemically more robust than MO, as the ether linkage is more stable against hydrolysis than the ester linkage and the phytanyl chain is fully saturated.     

Jet ejection from droplets near the Leidenfrost temperature

Abstract  

Droplets impinging on a hot surface that is near the Leidenfrost temperature were experimentally investigated. Ejection of jets from the top of the droplet was observed during the transient interaction between the droplet and a hot wall. We term this phenomenon jet ejection from droplets. When the bottom of the droplet initially impacts the hot surface, a jet is to be ejected from the top of the droplet. The jet ejection occurred only at low impact velocities and around the wetting limit temperature. It was not observed when droplets were dropped from large heights or when the surface was at a high temperature.     

PHENYLATION OF PYRIDINE BY PHOTOLYSIS OF DIPHENYL SULFONE

Abstract

The photolysis of diphenyl sulfone in neat pyridine or pyridine diluted with the organic solvent, with a high-pressure mercury arc lamp, was studied. The presence of acetone in the reaction system remarkably promoted photochemical conversion of the sulfone. The isomer distribution ratios (β > α > γ) of phenylpyridines produced during the reaction were clearly different from those (α > β > γ) so far reported for a free-radical phenylation of pyridine. Benzenesulfinic acid produced in the reaction was separated from the product mixture and identified as its S-benzylthiuronium derivative.     

Polymerization of Acrylamide in Aqueous Solution of Poly(N‐isopropylacrylamide) at Lower Critical Solution Temperature

Acrylamide (AAm) was found to polymerize in a solution of poly(N‐isopropylacrylamide) (PNIPAAm) in water at around its lower critical solution temperature (LCST) (32°C) without any initiators. This phenomenon was specifically observed in aqueous solutions of the polymers having LCST such as PNIPAAm and poly(methylvinylether) (PMVE). AAm polymerized only when PNIPAAm and AAm were dissolved in water below LCST of PNIPAAm and then the solution was warmed up to the polymerization temperature (40°C). On the other hand, the polymerization of AAm did not proceed when AAm was added into aqueous PNIPAAm solution during and after the phase separation above 32°C. Furthermore the polymerizability of AAm was remarkably affected by the concentration and molecular weight of the PNIPAAm additives. Under the condition of lower PNIPAAm concentration (0.30 mol/L), the increase in the molecular weight of PNIPAAm considerably increased the molecular weight of the resulting PAAm but decreased the yield of PAAm. Under the condition of higher PNIPAAm concentration (0.60 mol/L) the polymerizability was not so affected by the molecular weight of PNIPAAm, while the molecular weight of PAAm formed by using higher molecular weight PNIPAAm was higher than those of PAAm formed by using lower molecular weight PNIPAAm. Moreover, the molecular weight of PAAm formed by the PNIPAAm induced polymerization of AAm was much higher than that of the polymer obtained by the radical polymerization using AIBN in THF or VA‐ 061 in water.     

Fully automated reagent peak‐free liquid chromatography fluorescence analysis of highly polar carboxylic acids using a column‐switching system and fluorous scavenging derivatization

In this study, we combined a column‐switching system with a fluorous scavenging derivatization method to develop a fully automated reagent peak‐free LC fluorescence detection protocol for the analysis of highly polar carboxylic acids. In this method, highly polar carboxylic acids were derivatized with fluorescent 1‐pyrenemethylamine in the presence of 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide and 1‐hydroxy‐1H‐benzotriazole. Residual excess of the unreacted reagent was tagged with 2‐(perfluorooctyl)ethyl isocyanate and then removed selectively using a fluorous column‐switching system placed in front of an analytical reversed‐phase column. The signal of the fluorous‐tagged unreacted reagent was completely absent in the resulting chromatograms; therefore, it did not interfere with the quantification of each acid especially those eluted before 20 min. The detection limits (S/N = 3) for the examined acids were in the range from 4.0 to 22 fmol per injection. We have applied this method to comparative analysis of highly polar carboxylic acids in urine samples obtained from diabetes mellitus type‐II model mice and their control.     

Facile Synthesis of Oxamides by Efficient Trapping of Carbamoyl Lithiums with Isocyanates

Unsymmetrical oxamides are conveniently synthesized in good yields by a new trapping reaction of unstable carbamoyl lithiums with isocyanates.