Semiconductor-metal phase diagram of Co-doped NiS2

The phase diagram of the semiconductor-metal and antiferromagnetic transitions in 5 at.% Co- and 7 at.% Co-doped NiS₂ is determined from the electrical resistance measurements below room temperature to 77 K at pressures up to 35 kbar. It is indicated that the antiferromagnetic transition occurs in both semiconducting and metallic phases.     

γ Radiolysis of polyethylene grafted with styrene

γ Radiolysis of polyethylene grafted with styrene of 0–76 wt % was carried out at 30–100°C in vacuo with a dose rate of 6.35 × 10⁵ rad/hr. The formation of hydrogen and trans-vinylene unsaturation decreased as the content of styrene unit in polymer increased and the rate of formation was described by zero-order formation kinetics with respect to each concentration combined with first-order disappearance. The gel fraction changed with the content of styrene unit according to irradiation time and temperature. The gel data were evaluated by using the Charlesby–Pinner equation. Kinetic analysis showed that in γ radiolysis of polyethylene grafted with styrene the formation of hydrogen is somewhat retarded, the crosslinking and main chain scission are accelerated, and the disappearance of hydrogen and formation and disappearance of trans-vinylene unsaturation are almost entirely unaffected. On the basis of these results the reactions induced by γ rays in graft polymer were discussed in connection with the reaction mechanisms of the γ radiolyses of polyethylene and polystyrene.     

Synthesis of platinum complexes of 2-aminomethylpyrrolidine derivatives for use as carrier ligands and their antitumor activities

In order to study a new antitumor platinum complex, various platinum complexes were prepared from 2-amino-methylpyrrolidine derivatives synthesized to serve as carrier ligands and tested for their antitumor activity against Colon 26 carcinoma (s.c.-i.p. system) and P388 leukemia (i.p.-i.p. system) in mice. 2-Aminomethylpyrrolidine proved to be the most effective carrier ligand in its amine derivatives. The structure-activity relationships of the carrier ligands in the platinum complexes with dichloro, oxalato, 1,1-cyclobutanedicarboxylato and dichlorodihydroxo as leaving group were clearly shown on the Colon 26 carcinoma screen and were as follows: the antitumor activity of the platinum complexes with any leaving groups was considerably decreased by the substitution of hydrogen by alkyl group (Me, Et) on nitrogen of aminomethyl and the effects of 1,1-cyclobutanedicarboxylato Pt(II) complexes completely disappeared with the same substitution on nitrogen of pyrrolidine. In all the tested platinum complexes 2-aminomethylpyrrolidine(1,1-cyclobutanedicarboxylato)platin um(II) (15) exhibited the most potent antitumor activity. 15 was superior to 1,1-cyclobutanedicarboxylatodiammineplatinum(II) (CBDCA) and similar to cis-diamminedichloroplatinum(II) (CDDP) on the Colon 26 carcinoma screen but it was inferior to CBDCA and CDDP on the P388 leukemia screen. Furthermore, 15 showed more potent antitumor activity than CBDCA against Colon 38 carcinoma (s.c.-i.p. system).     

Ion chromatography for determination of nitrite and nitrate in seawater using monolithic ODS columns

A fast and highly sensitive ion chromatographic method using monolithic ODS columns was developed for the determination of nitrite (NO2-) and nitrate (NO3-) in seawater. Two monolithic ODS columns (50 mm x 4.6 mm i.d. + 100 mm x 4.6 mm i.d.) connected in series were coated and equilibrated with 5 mM cetyltrimethylammonium chloride (CTAC) aqueous solution. The column efficiency with 0.5 M NaCl as the mobile phase did not decrease in spite of the increase in flow rate of the mobile phase. Thus, good chromatograms were obtained within 3 minutes for NO2- and NO3 in artificial seawater without interferences by coexisting ions. The detection limit (S/N = 3) with UV detection at 225 nm was 0.8 and 1.6 microg/L for NO2- and NO3-, respectively. The characteristics of the monolithic CTA(+)-coated ODS columns were discussed. The present method was successfully applied to the fast and sensitive determination of NO2- and NO3- in real seawater samples.     

Reaction of poly(vinyl chloride) with superoxide anion

Reaction of poly(vinyl chloride) (PVC) with superoxide anion was carried out in tetrahydrofuran (THF) at 40°C in a nitrogen atmosphere. Remarkable changes in infrared (IR) spectra of the samples treated with superoxide anion were observed in the following regions: ca. 3300, 1680, 1620, and 765 cm^?1, which suggested the formation of hydroxyl groups, α,β-unsaturated ketone groups, and ethylenic structures. Ultraviolet–visible spectra also showed the formation of polyene structures. The content of chlorine in the polymer decreased and that of oxygen increased with reaction time. The reaction mechanism was discussed on the basis of these results.     

Photoinduced dissolution and redeposition of Au nanoparticles supported on TiO2

Au particles (mean size ca. 3 nm) supported on TiO(2) particles were irradiated by UV light (>300 nm) in aqueous solutions at 278 K. Photo-induced dissolution of Au nanoparticles followed by redeposition occurred in aqueous solutions containing halogen ions. The dissolution of Au nanoparticles yielded a Au(III) complex with a halogen ion; subsequent reduction of the Au(III) complex caused precipitation of larger Au particles on TiO(2).     

Two-stage irradiation study on propagation and termination in the γ-radiation-induced polymerization of ethylene in liquid carbon dioxide

The propagation and termination reaction in the γ-radiation-induced ethylene polymerization in liquid carbon dioxide were investigated by a two-stage irradiation. After irradiation at high dose rate, the polymerization occured at a considerable rate under the extremely low dose rate without initiation. The absolute propagation rate was determined in the second stage to be proportional to the square of ethylene fugacity and depended slightly on dose rate. The apparent activation energy for the propagation reaction is ?9 kcal./mole. From these observations which are the same as those in bulk polymerization, it is concluded that carbon dioxide acts as a diluent of ethylene monomer in the propagation reaction. Also, carbon dioxide was shown to be inactive to the growing radicals without irradiation, but oxygen which is produced by the radiolysis of carbon dioxide at high dose terminates the growing radicals with formation of carbonyl in the polymer.