Lithium ion battery has been widely used for cellular phones, notebook personal computers and camcorders.
Development and technology trend of lithium ion battery are reviewed. The origin of lithium ion battery was the research on secondary battery using an electroconductive polymer, polyacetylene, as the negative electrode. Then the focus was shifted from polyacetylene to carbonaceous materials which also have π electrons. They were combined with a lithium ion-containing metal oxide, LiCoO₂ as the positive electrode.
Capacity of the lithium ion battery has been increased every year and present capacity is twice as much as the initial value.
This improvement of capacity has been achieved by improvement of carbonaceous materials.

View full abstract

ZnS:Mn²⁺ nanoparticles were synthesized from aqueous solutions of Zn(NO₃)₂, Mn(NO₃)₂ and Na₂S under pH3.0, 6.8 and examined by using absorption and luminescence spectra. The absorption spectra changed as functions of pH and time(Fig. 1). Orange luminescence due to Mn²⁺ substituting for Zn²⁺ in the ZnS lattice was strongly observed in addition to both weak ultraviolet luminescence due to Mn²⁺ attaching to the surface of ZnS nanoparticles and blue luminescence due to vacancies in the lattice, which are shown in Fig. 2. These luminescence spectra changed by pH and time. These properties were most possibly related to the stability of the nanoparticles. Based on these findings, sol-gel glasses doped with ZnS:Mn²⁺ nanoparticles were synthesized from the above starting materials and tetramethoxysilane. The absorption spectra were shown in Fig. 3. Orange luminescence was considerably observed in the sol-gel glass as shown in Fig. 4. The particle diameter in sol-gel glasses was estimated to be 3.1-3.8nm from the excitation spectra shown in Fig. 4. These results suggest that sol-gel glasses doped with ZnS:Mn²⁺ nanoparticles can be prepared by the method employed in this experiment, although further studies are required to obtain more luminous sol-gel silica.

View full abstract

The catalytic oxidation of chlorobenzene(CB) and benzene(B) which are precursors for the formation of dioxins at municipal solid waste incinerators was carried out over a hematite catalyst with a micro catalytic pulse reactor. CB was decomposed to B, followed by gradual oxidation to CO₂. Benzene was directly decomposed to CO₂ and the apparent reaction rates of both catalytic decomposition could be expressed as the first order at 673-973K. The deactivation of catalyst by repeated pulse reactions and the reactivation of used catalyst by oxidation with O₂ were studied from the viewpoint of change in the composition of catalyst.

View full abstract

Groundwater pollusions by nitrates have received increasing attention in many locations in the world. The Environmental Agency of Japan has announced in Feb.1999 to regulate the maximum contamination of nitrates and nitrites to be less than 10mg/L, and it is an urgent problem to cope with the situation. The present paper demonstrates that catalytic decomposition of trace amounts of nitrates and nitrites in aqueous phase on a level with drinking water could be carried out under mild conditions of atmospheric pressure of hydrogen at room temperature. Supported bimetallic catalysts, copper-palladium-on-carbon, with high copper-contents revealed excellent activity for nitrates, while single metallic palladium-on-carbon was much more effective than bimetallic catalysts for nitrites. Thus, the intermediate nitrite unfortunately accumulated in solution in the decomposition of nitrate on bimetallic copper-palladium-on-carbon, but the nitrite could be removed in situ with great ease in the presence of isolated palladium free of copper. Powder XRD suggested the active species as Cu₃Pd for nitrate decomposition and supported state of metallic components was discussed with portrayals in reference to the catalyst activity.

View full abstract

Although platinum and rhodium have usually been used for conventional three-way catalysts, development of a rhodium-free automotive catalyst is a recent target of investigation for reducing the cost of catalyst. In this regard, we attempted to develop an automotive three-way catalyst based on Pd only. The improvement an alumina-loaded Pd catalyst was tried with the addition(around 10wt%) of transition metal oxides, and it was found that several oxides, especially NiO, showed a remarkable promoter action. Encouraged with this fact, aluminates of various transition metals were synthesized to be loaded with Pd. Some of the Pd-loaded catalysts thus prepared, especially one supported on Ni-aluminate were found to exhibit higher performances in light-off activity as well as three-way catalytic activity than the conventional Pd catalyst supported on alumina. It was revealed that the Ni-aluminate was a spinel phase solid solution between NiO and γ-Al₂O₃ and the Ni/2Al atomic ratio (x) as well as calcination temperature gave significant influences on its properties. The Ni-aluminate with x=0.5, calcined at 800°C, turned out to be the best support of Pd. This particular catalyst proved satisfactorily high performances as a three-way catalyst in engine dynamometer and chassis dynamometer tests.

View full abstract

Oxidation of CH₄ under lean condition(800ppm) and CO₂ reforming of CH₄ were carried out using Rh/ZrO₂ catalysts with different metal dispersions. It was found that both reactions showed a similar structure-sensitive behavior: The TOF decreased with increasing of Rh dispersion. It is suggested that the rate determining step is dissociative adsorption of CH₄ for both reactions, and strong Rh-O bonds in smaller Rh crystallites may lead to a suppression of the dissociative adsorption of CH₄ on the Rh surface.

View full abstract

The title novel hole transport materials(HTM)(1-3) have been synthesized in good yields by the modified Ullmann coupling reaction of the corresponding bis(4-aminophenyl) chalcogenides with p-iodotoluene in the presence of Cu, K₂CO₃ and 18-crown-6 in o-dichlorobenzene. From the electrochemical and spectroscopic measurements, it was evaluated that the HOMO levels of these materials are nearly the same as that of TPD, the most typical hole transport material, while the LUMO levels are fairly higher. Electroluminescence devices with the layer structure ITO/HTM(50nm)/Alq₃(50nm)/Al(500nm) were fabricated by successive vapor deposition of the materials under vacuum onto an ITO-coated glass. All the devices utilizing 1-3 emitted green light from Alq₃ and showed higher luminous efficiency than the device using TPD. In particular, the highest luminance of 2298cd/m² was observed for the device of the sulfide-derivative(1).

View full abstract

The red alga genus Laurencia is a well known source of polyhalogenated sesquiterpenes, some of which possess physiological activities. Structures of typical sesquiterpenes from Laurencia involve mainly bisabolane, chamigrane, and laurane skeletons. Treatment of prepacifenol epoxide(2) with 5% TFA in CCl₄ provided new three compounds(7, 8 and 9) together with johnstonol(4) and pacifenediol(5). Also, reaction of 4 with TFA afforded a mixture of 1, 6-dibromo-5-chloro-11-hydroxy-5, 9, 12, 12-tetramethyl-2-oxatricyclo[6.3.1.0^{3, 8}]dodecan-10-one(6), 7, 9 and TFA ester of 5(10). Similar treatment of 5 produced only 10. The structures of these compounds were elucidated, and plausible reaction pathway was proposed.

View full abstract

Amphiphilic poly[N-(2-hydroxypropyl)methacrylamide]s (PHPMA) having long alkyl moieties as terminal groups, PHPMA-C₁₂, PHPMA-DC₁₂ and PHPMA-C₁₈, were prepared by radical polymerization of N-(2-hydroxypropyl) methacrylamide (HPMA) initiated with lipophilic azo-initiators such as 4, 4′-azobis(dodecyl 4-cyanopentanoate) (VA-C₁₂), 4, 4′-azobis[(2-dodecyloxy-1-dodecyloxymethylethyl) 4-cyanopentanoate] (VA-DC₁₂) and 4, 4′-azobis(octadecyl 4-cyanopentanoate) (VA-C₁₈) in the presence of 2-mercaptoethanol as a chain transfer reagent. An amphiphilic polymer having octadecyl moieties as both terminal groups, PHPMA-2C₁₈, was also prepared by radical polymerization of HPMA initiated with VA-C₁₈ in the presence of 1-octadecanethiol(ODT) as a chain transfer reagent. From the fluorescence measurements of aqueous polymer solution using 1-(6-dimethylamino-2-naphthyl)-1-dodecanone (DMAND) as a fluorescent probe, the critical micelle concentrations (CMC) of PHPMAs were found to be PHPMA-C₁₂>>PHPMA-DC₁₂>PHPMA-C₁₈>>PHPMA-2C₁₈ in order. From SAX measurements of a drug model consisting of PHPMA-C₁₈ and cholesterol, it was suggested that cholesterol molecules are incorporated in a hydrophobic domain formed by the terminal octadecyl groups. It was also found that no acceleration in the enzymatic reaction of thrombin and a synthetic substrate S-2238 occurred in the presence of PHPMA-C₁₂, PHPMA-C₁₈, or PHPMA-2C₁₈. These PHPMAs are thus expected as carrier molecules of drug delivery system.

View full abstract

Tautomeric equilibria of methyl p-substituted benzoylacetate were studied by ¹H-NMR spectroscopy. Equilibrium constants(K_t) depend greatly on solvents and substituents. Regression analysis of K_t for methyl benzoylacetate with solvatochromic parameters proposed by Kamlet and Taft revealed that the polarity and the hydrogen bond donor acidity of the solvent are the major factors of the K_t-variations as a result of preferential solvation of the ketonic tautomer. The equilibrium constants for p-substituted benzoylacetates were evaluated in chloroform and acetonitrile. Hammett’s plot of the constants have negative ρ values in both solvents, indicating that the equilibrium shifts to the enolic direction as electron-withdrawing power of the substituents on phenyl ring increases.

View full abstract