Dynamical properties of nucleus boundaries in photoinduced structural change

Dynamics of the boundaries of photoinduced nuclei in electron–phonon systems is theoretically studied. By regarding the spatial distribution of the excited electronic state population as a geometric pattern, we applied the multifractal analysis to it and calculated the temporal behavior of the fractal dimension f(α)$f(\alpha )$ as a function of the Lipschitz–Hölder exponent α, which is an appropriate method for understanding the cooperative relaxation process of photoexcited states. We found that the incubation period observed in various types of photoinduced cooperative phenomena corresponds to the formation of embryonic nuclei which is driven by nonadiabatic/adiabatic transition between electronic states during the relaxation of the Franck–Condon state.     

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.     

A novel stereocontrolled approach to steroid side chain construction: asymmetric synthesis of potential synthon of the vitamin D series

Stereocontrolled synthesis of (?)-de-AB-8-oxa-cholest-14-en-9-one (2) as an optically active form was achieved starting from the methylene ketone (7). This work constitutes a formal synthesis of de-AB-cholestan (1).     

Synthetic approach to grayanotoxins and asebotoxins: a new construction of the a-homograyanotoxane ring system

The tetracyclic compounds ～3 and ～4 corresponding to A-homograyanotoxane system were synthesised by a thermolysis of the benzocyclobutene ～8, followed by a Wagner-Meerwein rearrangement of the kaurane type of compounds ～15 and ～16.     

Determination of isoniazid in tablets by second-derivative ultraviolet spectrophotometry of scraped-spot solutions from thin-layer chromatography

Isoniazid in solutions of tablets was separated by thin-layer chromatography (TLC). The portion of the precoated plate carrying the isoniazid spot was cut out and the coating was scraped off into water. The isoniazid was quantified in the solution, without separation of suspended adsorbent, by second-derivative spectrophotometry, which eliminated the background in the zero-order spectra. Relative standard deviations (n = 5) were <1%. Results obtained for commercial tablets were in good agreement with those given by a liquid-chromatographic method.     

Dielectric relaxation in concentrated solutions of poly(γ-benzyl-L-glutamate)

Measurements of dielectric constant and loss, broad-line nuclear magnetic resonance, and differential thermal analysis of concentrated solutions of poly(γ-benzyl-L -glutamate) (PBLG) were carried out to determine the effects of intermolecular interactions on the mobility of the side group and the solvent (dichloromethane or dioxane). Only one dielectric loss peak due to the cooperative motion of the side group and the solvent was found. The activation energy of this relaxation process varied from 3 to 47 kcal/mole with increasing concentration of PBLG from 20 to 100% by weight accompanied with steep increases at about 40 and 80%. This result is explained as due to entanglement of neighboring side groups. In NMR, narrowing of the line was observed near the temperature where the dielectric loss was observed. The glass transition was also observed by differential thermal analysis. From these results it was concluded that the relaxation observed in PBLG solution and in pure PBLG have the nature of primary or α relaxations.     

Relationship between reactivity and 13C chemical shifts of benzocyclobutenes

¹³C NMR spectra of benzocyclobutene derivatives have been investigated; substituent effects and the relationship between the chemical shifts and the reactivity of their cyclobutene ring are discussed.     

Preparation and certification of tea leaves reference material

Summary Tea leaves reference material was prepared and certified for elemental composition. Japanese green tea leaves were ground, sieved to pass a 80-mesh screen, blended and bottled. The prepared material satisfied the homogeneity criteria for a reference material. Trace element analysis of the material was carried out by flame and graphite furnace atomic absorption and inductively coupled plasma atomic emission spectrometry.Certification of the material was performed using the data obtained by various analytical techniques and certified values are provided for Al, Ca, Cd, Cu, K, Mg, Mn, Na, Ni, Pb and Zn. The elemental composition of the tea leaves reference material is considered typical of Japanese green tea leaves.