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  • Author: S. Yoshida x
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Abstract

The aim of the present study was to gain further understanding of the precursors in tobacco of four polycyclic aromatic amines (PAAs) - 1- and 2-aminonaphthalene, 3- and 4-aminobiphenyl. We carried out non-isothermal pyrolysis of the residues, which were obtained after extraction of tobacco cut filler with methylene chloride followed by extraction with water, under three different pyrolysis conditions (target temperature 800 °C / 800 °C / 400 °C and O2 concentration in carrier gas 0% / 20% / 3%, resp.). The yields of the four PAAs obtained by the pyrolysis of each sample were evaluated. Several nitrogenous components in the sample were also analyzed. The results under all these pyrolysis conditions showed that 1) the methylene chloride-soluble fraction, in which 50-60% of nicotine was extracted, did NOT contribute significantly contribution to the yields of the four PAAs; 2) the watersoluble fraction, in which most of the nitrogenous inorganic ions and amino acids were extracted, contributed at an average of about 30% to total PAA yield; and 3) the insoluble residue, in which only protein was detected during the investigation of the nitrogenous components in the present study, showed the highest contribution, 50-60% of the four PAAs formed. Consequently, it is concluded that protein-like components in tobacco contribute highly to the formation of the four PAAs by tobacco pyrolysis.

Summary

Sorption of actinides onto negatively charged mineral surfaces was investigated under conditions that actinides were predominantly present as anionic complex species. U(VI), Np(V) and Sn(IV) were prepared as 1 mol kg-1 Na-ClO4/OH solutions and equilibrated with γ-Al2O3 at pcH 11-13.6 where these elements form UO2(OH)4 2-, NpO2(OH)2 - and Sn(OH)5 - species, respectively. Sorption of Np(IV), Th(IV) and Am(III) on amorphous SiO2 and on γ-Al2O3 was investigated in 0.03-0.3 mol kg-1 Na-HCO3/CO3 solutions where these actinides are expected to be stable as anionic carbonate complexes. Distribution coefficients of U(VI), Np(V), Sn(IV), Th(IV) and Am(III) decreased with the increasing pH or with the increasing carbonate concentrations. The monotonous decrease in the distribution coefficients in the investigated pcH range suggests that anionic complex species of actinides were not sorbed on negatively charged mineral surfaces. A proportional relation was found between the experimentally obtained K d values and calculated mole fraction of electrically neutral species in equilibrated solutions. Sorption occurs under the condition that both actinides and mineral surfaces are negatively charged because minor neutral species are sorbed on mineral surfaces.

Abstract

Dose rate of cosmic-ray origin neutrons (abbreviated to “cosmic neutrons”) at aviation altitude was estimated based on the measurements at Mt. Fuji. Cosmic neutrons were measured in a facility of the Mt. Fuji Weather Station located at the summit of Mt. Fuji, the highest mountain in Japan (3776 m in altitude), in the summer of 2008 and 2009. The average of 1 cm ambient dose equivalent H*(10) for two measurements was verified by numerical model simulation and then used to empirically estimate the solar force field potential (FFP). The H*(10) rates at aviation altitude estimated from the measurements at Mt. Fuji were compared to those obtained in in-flight measurements onboard a civilian aircraft flying near Mt. Fuji at the time between the two measurements at the mountain. According to the results obtained, we expect that the empirical estimation based on the measurements at Mt. Fuji will work effectively for dosimetry of cosmic radiation in troposphere.

Five photosynthesis inhibiting herbicides were compared for their mobility in soil columns used as the penetration model. The vertical movement of these compounds in soil was analyzed by a newly developed technique in which herbicide distribution was determ ined by the intensity of chlorophyll fluorescence in Chlorella cells suspended in aqueous extracts of soil samples from various depths. With the aid of a fluorescence microplate scanner, measurement of chlorophyll fluorescence was performed with great efficiency. Photosynthesis inhibiting activity of tested herbicides was determined beforehand by the same method and served in calculating herbicide concentrations in sample extracts. Among tested compounds, hexazinone showed the greatest mobility and diuron the smallest, suggesting water solubility is one of the factors which govern the soil mobility of herbicides.

Abstract

The mode of action of three types of conjugated enamine compounds was investigated by means of thermoluminescence measurement. Cyanoacrylate and 2-(l-ethoxyethylam inom ethylidene)- 4-dodecyl-5,5-dim ethyl-cyclohexane-1,3-dione (ACm12) converted the B-band (30 °C) arising from S2QB - charge recombination to a downshifted 6 °C-band. This band was proved to be identical with the DCM U-induced Q-band (6 °C) arising from S2QA - recombination, indicating that these two compounds block QA to QB electron transport. 3-(1-dodecylam inopropyridene)-6- methyl-2H-pyran-2,4-dione (APp12 ), on the other hand, induced an abnormal band peaking at 15 °C between the Q-band and B-band. From the gradual downshift of its peak temperature in titration experiments, this band was assigned to arise from a modified S2QB - charge pair, in which the properties of either QB - or S2 is altered. The 15 °C-band showed normal oscillation during the first 2 flashes, but the oscillation was interrupted thereafter. Another therm oluminescence analysis by use of post flash low temperature illumination protocol revealed that APp12 affects neither QA to QB nor QB 2- to PQ electron transport, but specifically blocks S3 to S0 transition. These results indicate that APp12 is a new-type PS II inhibitor.

Summary

Irrespective of low bioavailability, some plant species accumulate Y and rare earth elements (REEs) to a great extent (accumulator species). The uptake mechanisms of Y and REEs were investigated for autumn fern, one of accumulator species. For comparison, plant species which accumulated poorly REEs (non-accumulator species) were also studied. In the present investigation, two noticeable phenomena were observed. (I) Autumn fern showed no ionic-radius dependence of Y-REE uptake by leaves, while non-accumulator species showed an extremely high uptake for Y compared with REEs. (II) Y-REE uptake by autumn fern was influenced by the addition of chelating reagents to the uptake solution, while no effect was observed for non-accumulator species.