The 13C NMR titration shifts of sulphonic acids

Carbon-13 chemical shifts of a number of alkyl and aromatic sulphonic acids in sulphuric acids in sulphuric acid and strongly basic deuterium oxide have been compared. The titration shifts are relatively small for carbons near the sulphonyl group, but are comparable with those of other organic acids or bases for carbons remote from the deprotonation sites.     

Studies on the syntheses of heterocyclic compounds—DXLVIII : Synthesis of a hasubanan ring system from the benzylisoquinoline reticuline

The synthesis of a cepharamine analogue (19) from reticuline (1) by phenolic oxidation is reported. Reticuline was converted into the methine base (13b), whose dihydro compound (14c) was oxidised to the seco-morphinandienone (17b). Michael-type cyclization of 17b, followed by an isomerization of the enone (18) gave the cepharamine-type compound (19).     

Radiation-induced cis–trans isomerization of polyisoprenes and temperature dependence of the equilibria

The cis-trans interconversion of polyisoprenes in solutions induced by γ-radiation in the presence of a sensitizer, which is any one of organic bromides or n-butyl mercaptan, was studied by using hevea and gutta percha as starting substances. The percentage cis remaining or converted after irradiation were determined by the infrared absorption. The equilibrium constants for the interconversion at 22, 60, and 100°C. were found to be 3.00, 5.25, and 7.33, respectively. The first-order rate constants for cis → trans and trans → cis isomerizations at 22°C. were calculated to be 9.05 and 2.91, respectively. The results were interpreted by the mechanism proposed by Golub, according to which the double bonds from π complexes with radiolytic fragments from sensitizers give a radical transition state capable of interconversion. However, our results showing that heating shifts the equilibrium toward trans isomer are not in accord with the mechanisms of the radiation-induced isomerization of polybutadiene of Golub and those for photoisomerization of aromatic azo compounds.     

Spectroscopic studies of microwave-excited plasma

Manganese solution was sprayed into a microwave-excited plasma torch (2450 MHz and ca. 200 W), whose profile was examined; the electron temperature, the degree or ionization and the total number of atoms and ions were estimated. Effects of alkali and alkaline earth metals were found to depend on the ionisation potentials of both manganese and the added metal.     

Nb and N co-doped TiO2 for a high-performance deNO x photocatalyst under visible LED light irradiation

By a facile and rapid microwave-assisted hydrothermal reaction at 190 °C for 30 min, niobium and nitrogen co-doping TiO₂ nanoparticles were prepared. The obtained samples were characterized by XRD, UV–Vis spectroscopy, EDX analysis, and BET measurements. To evaluate the photocatalytic activity, destruction of NO _x gas under the irradiation of several LED lamps with various wavelengths were carried out. Although co-doping of Nb with N into TiO₂ resulted in the decrement of the specific surface area, it was useful to improve the photocatalytic activity for the oxidative destruction of NO, probably due to the effective reduction of the anion vacancy in the lattice which acts as the recombination center of the photo-induced electrons and holes.     

Analysis of carcinogenic mechanisms of liver cancers induced by chronic exposure to alpha-particles from internally deposited Thorotrast

For the successful space traveling, the possibility for the detrimental effects on health including cancer caused by exposure to cosmic rays is a major concern. Thorotrast is a 25% colloidal solution of natural -emitter, thorium dioxide used as a radiological contrast medium during World War II. It caused hepatic malignant tumors by the local exposure to -particles decades after administration. Thorotrast-induced liver tumors consist of hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), and angiosarcoma (AS) at nearly the same instance. We analyzed mutations of the p53 and the K-ras genes, microsatellite instability (MSI), and loss of heterozygosity (LOH) in Thorotrast ICC. The major p53 mutation observed in Thorotrast ICC was the transition type, suggesting that reactive oxygen species are not likely involved in gene mutations of Thorotrast cancers. MSI frequency in Thorotrast ICC was significantly higher than that in non-Thorotrast ICC. MSI was partly attributed to the inactivation of the hMLH1 mismatch repair gene via methylation of the promoter region and to monoclonal expansion of cells with mutations. Thorotrast ICC shared LOH pattern with non-Thorotrast HCC and ICC. Furthermore, we could assess the distribution and the quantity of deposited thorium using an imaging plate and a BAS image analyzer. The distribution of thorium deposits was not always consistent with that of apoptotic cells. We conclude that Thorotrast ICC is developed through complex carcinogenic steps including genomic instability and mutations of crucial genes during remodeling of the liver architecture. We emphasize how pathological specimens from Thorotrast patients are valuable for assessing the relevance of long-term exposure to low dose -particles to radiation carcinogenesis.