Catalytic activity of various Ti0₂-based catalysts was examined for NO-NH₃ and CO-0₂reactions. Precious metals supported on TiO₂ were very active for the removal of CO, but they were less active for the removal of NO. Transition metal oxides were poorly active for the removal of CO, whereas some such as V₂0₅-Ti0₂ were very active for the NO removal. Thus a combination between a precious metal and a transition metal oxide was expected to bring about high catalytic activity for the simultaneous removal of NO and CO. In fact, V₂0₅ supported on Pt-Ti0₂ (denoted V₂0₅-Pt-Ti0₂, Pt=0.01 wt%, V/Ti=1/9) was highly active for both reactions at 250 °C. However Pt supported on V₂0₅-Ti0₂ was highly active only for the removal of NO, indicating that the order of supporting Pt and V₂0₅ on TiO₂ influences the catalytic activity. The adsorption of NO, NH₃ and CO was measure d by a pulse adsorption method. All the three gases were adsorbed on Pt-TiO₂, but only NH₃ was on V₂0₅-Ti0₂. This result suggests that CO reacts with 0₂ on Pt while the NONH₃reaction occurs on both Pt and V205.

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A large amount of cyclohexene oxide is obtained by the addition of benzylviologen bromide (BVBr₂) in the air-equilibrated acetonitrile solution containing (5, 10, 15, 20-tetraphenylporphyrinato)manganese(III) chloride ([Mn^III(tpp)]Cl) as amonooxygenase catalyst, zinc powder as a reductant, benzoic anhydride as an acylating agent and cyclohexene as a substrate. The turnover number of the catalyst of about 100 is obtained for 12 h (reaction time). The result implies that BV²⁺ ion plays an important role as an electron mediator from zinc powder to manganese porphyrin. Further the effectiveness of BV²⁺ ion is discussed in detail from the dependence of the quantity of the produced epoxide on the concentration of [Mn^III(tpp)]Cl and 1-methylimidazole as an axial ligand.

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The single crystals of Mn₅Si₃ (hexagonal system), MnSi (cubic system) and Mn₂₇Si₄₇(tetragonal system) were prepared by the high temperature tin solution method using manganese metal powders and silicon powders as starting materials in an argon atmosphere. The conditions for obtaining these crystals with one-phase materials and relatively large size were determined. As-grown Mn₅Si₃, MnSi and Mn₂₇Si₄₇ single crystals were used for chemical analysis and measurements of unit cell dimensions, densities, Vickers microhardness and electrical resistivity. The optimum conditions for growing Mn₅Si₃, MnSi and Mn₂₇Si₄₇single crystals are the following atomic ratios of starting materials (Si/Mn, Sri/Mn), soaking temperature and soaking time; Si/Mn =0.22, Sn/Mn =10.17, 1100 °C, 10 h for Mn₅Si₃, Si/Mn =1.0, Sn/Mn =10.17, 1100 °C, 10 h for MnSi and S i /Mn =1.74, Sn/Mn =6.36, 1000 °C, 20 h for Mn27Si47, respectively. Under these conditions, Mn₅Si₃ single crystals, having grayish and metallic luster, were generally obtained in the form of prismatic shape extending to direction, MnSi single crystals, having grayish and metallic luster, were generally 708 f t 1992 No.7obtained in the form of prismatic shape extending to direction, and Mn₂₇Si₄₇si ngle crystals were grayish and metallic luster, having a nearly spherical polyhedral. The largest crystals prepared have the maximum dimensions of about 0.1 mm x O.1 mm x 6.4 mm for Mn5Si3, 0.9 mm x 1.0 mm x 9.2 mm for MnSi and O.2 5 mm x O.2 5 mm x 0.2 5 mm for Mn27S i4.7The results of chemical analysis and measurements of unit cell dimensions, Vickers microhardness (H), densities (d. ), electrical resistivity (p) are as follows:
Mn5Si3; M n5.45Si3, a = 6.9 09( 2) Å, c = 4.815( 1) Å, V=199.0 5( 3 ) Å3, dm= 5.9 5( 2 ) gfcm3, Hy = 820±-3 0 k gf/rnm², p = 3500±230 i tC-c²m MnSi; Mn0 9 8Si, a =4.5594( 6 ) Å, V=94.7 8( 1 )Å., dm= 5.8 0( 1 ) g/cm³, Hy=1100±-40k gf/mm2, = 3 200±-1 8 0/ I Q c m Mn27Si47; Mn2 7.9 8Si4 7, a=5.530( 1 ) Å, c=117.8 6( 2 ) Å, V=3604.2 6( 8 ) Å3, dm= 5.17( 2 ) g/cm³

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Positive and negative ion chemical ionization (PCI, NCI) mass spectra of 30 pesticides (insecticides 7, fungicides 12, herbicides 11) (Table 1) frequently used in golf course maintenance were obtained. The spectra were compared with the electron ionization (EI) mass spectra of these compounds. In general because of the reduced fragmentation simpler mass spectra were obtained in PCI and NCI compared to EI. For the insecticides, MH⁺ ions were always present and these were frequently the base peak in PCI mode. In almost all cases, compounds possessing (C₂1-1₅0)₂PSO- structure generated fragment ions [(C₂1-1₅O)₂PS0](miz 169) in NCI (Figs.1, 2, Table 2). In fungicides and herbicides, MH⁺ ions were always produced but their ion intensities varied considerably according to their structure. Fragment ions reflecting the molecular structure of compounds were formed in most PCI spectra (Figs.3, 6, Tables 3, 4). Either 114-, (MH)^-, or specific fragment ions became the base peak in NCI and Cl ions were generated from the pesticides containing chlorine atom( s ) in a molecule (Figs.4, 7, Tables 3, 4). Ion abundances of significant ions in the spectra were determined by selected ion monitoring to estimate the ion abundance ratios of negative ion base peak/positive ion base peak (N/P) for each compound. The number of pesticide having an N/13 value of excess 50 was 17 and these compounds are recommended for high sensitivity detection by NCI.

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The interfacial adsorption equilibria of cationic and anionic dyes and ion associates formed between them were examined. A high-speed stirring apparatus was used for mixing of water and organic solvent. Phase separators with poly (tetrafluoroethylene) (PTFE) membrane and filter paper were used to separate an organic phase and an aqueous phase, respectively. The concentrations of species in each bulk phase were measured by absorptiometry. Four analogues of 1-alkyl-4-[4-(dialkylamino)phenylazo]pyridine, Methylene Blue and four analogues of Methyl Orange were examined. Chloroform, styrene, benzene and cyclohexane were used as organic solvents. Under vigorously stirring conditions, the interfacial adsorption of the dye ions was occurred. This resulted in a decrease in absorbance of an aqueous phase. The interfacial adsorptivity of the dye ions increased with an increase in their hydrophobicity. In the presence of both a cationic and an anionic dye, an ion associate formed was extracted into an organic phase, and when stirred vigorously, a decrease in absorbance was observed in an aqueous and an organic phase. The interfacial adsorptivity of the ion associate decreased with an increase in its hydrophobicity. Ion association constants at the interface were of the order of 10⁶ dm³ mol^-1, and decreased with an increase in carbon numbers of the dialkylamino group of the cationic and anionic azo dye.

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Oxidation of polycyclic aromatic hydrocarbons with sodium bromite (NaBrO₂) proceeded n a dioxane-water solution 4 efafnedcs toivaicet hlryoio ommtee mtfropirce2 in Athe presence of small amount of tributyltin chloride ((n-C₄1-1₉)₃SnC1).
nthracene, 9, 10-dihydroanthracene, fluorene, phenanthrene, acenaphthylene and acenaphthene were oxidized to anthraquinone, 9-fluorenone, 9, 10-phenanthrenequinone and acenaphthenequinone in high yield, respectively. NaBrO₂ is a valuable oxidizing agent for polycyclic aromatic hydr ocarbons. Reaction of oxidation is proposed as follows.
NaBrO₂ (n-C₄H₉)₃SnCl_??_(n-C₄H ₉)₃SnBrO₂ NaCl ( 1 )
(n-C₄H₉)₃SnBrO₂ C1₄H10_??_ C₁₄H₈O₂ (n-C ₄H₉)₃SnBr+H₂O ( 2 )
(n-C_4F1₉)₃SnBr NaBrO₂ (n-C₄H₉)₃SnBrO₂ NaBr( 3 )

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Peroxyl radicals produced by ozone-oxidation of polypropylene wer epursued by observing in situ ESR, the dependence of the ESR spectral intensities upon ozone-oxidation time and the time after the ending of ozone supply was investigated. The location of the radicals produced on the polypropylene was determined by ¹³C-NMR spectroscopy and the decomposition products of peroxyl radical were examined by IR spectroscopy and Idometory. The ozone-oxidation reaction mechanism of polypropylene reported previously was ascertained. The peroxyl radicals produced on tertiary carbon atom of polypropylene were more stable than secondary one of polyethylene.
The molecular weight of ozone-oxidized polypropylene and the molecular weight distribution were measured. The changes in the crystallinity, degree of orientation and double refraction of polypropylene by ozone-oxidation were examined, and also the changes in the thermal and mechanical properties were measured. Consequently, the molecular chains of polypropylene were broken in half within 30 min. The thermal and mechanical properties of the ozone-oxidized polypropylene were deteriorated, although the crystallinity, the degree of orientation, and the double refraction were same as that before ozone-oxidation.

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The preparation of polyacrylonitrile based activated carbon fiber (PAN-ACF) was investigated in order to obtain suitable conditions for the oxidation of PAN-fiber and activation of this oxidized PAN-fiber. PAN-fiber (0.9-5 denier) was oxidized at 225-255 °C in air. After activation of thus obtained oxidized fiber at 800-1000 °C, the activation behavior and the change in fiber strength, average pore diameter and benzene adsorption capacity were examined. At high activation temperature, the PAN-ACF with high strength and high benzene adsorption capacity were obtained at higer activation rate. The average pore diameter of PAN-ACF at high activation temperature was smaller than that at low activation temperature. The degree of oxidation was closely correlated with bonded oxygen content, moisture regain and specific gravity of the fiber. In the case of the activation, the suitable bonded oxygen content was 13% higher, which corresponded to moisture regain above 8% and a specific gravity above 1.37.

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Acrylic fiber (PAN-fiber) was treated with an aluminum salt solution or iron(III) salt solution. These fibers were then oxidized at 225 to 255 °Cin air for h. The coalescence of the oxidized fiber and rate of oxidation were examined. After activation of these oxidized fibers, the change in fiber strength, average pore diameter were also examined. As a result, the degree of coalescence and stabilization of oxidation were improved while the oxidation rate was accelerated by treatment of the PAN-fiber with the aluminum salt solution. It was found that the optimum aluminum salt was polyaluminum chloride, and the aluminum content (Al) was 200-410 ppm. With activation of these oxidized fibers by steam, PANactivated carbon fibers with high fiber strength and benzene adsorption capacity were obtained. The rapid increase in average pore diameter was observed at a specific surface area (SA) of 800 m²/g. Though this behavior was also observed in the case of iron(g) chloride, on the contrary, the average pore diameter decreased at SA of more than 1000 m²/g.

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The continuous and intermittent flow testing of chlorine and Methylene Blue 'removability in aqueous solution was conducted in a packed column with polyacrylonitrile (PAN) based activated carbon fiber (specific surface area: 750-4250 m²/g). Dependence of chlorine and Methylene Blue removability on specific surface area, space velocity and ashes were examined and compared to other activated carbon. As a result, PAN based activated carbon fiber indicated higher removability than that of granular activated carbon at a higher space velocity. In the case of continuous flow, the behaviors of removability for both chlorine and Methylene Blue changed rapidly at specific surface area of 900 m²/g, which corresponded to the change in average pore diameter. The optimum packing density was in the range of 0.070.13 g/ml in consideration of pressure drop and chlorine removabilty. It was found out that the ashes in activated carbon fiber were effective in removing chlorine. In the case of intermittent flow, the chlorine removability was higher than that of continuous flow.

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The physical properties and the sterilization effects of silver supported polyacrylonitrile based activated carbon fiber (PAN-ACF) were invesigated for use of these fibers in a water purifier filter. The amount of silver on ACF was adjusted to be 100-70000 ppm by steeping PAN-ACF (SA: 500-920 m²/g) in AgNO₃ aqueous solution. PAN-ACF showed a high amount of supported silver and showed a high silver dispersion as observed by scanning electron microscope (SEM). The silver supported PAN-ACF (SA: 860 m²/g, Ag: 5600 ppm)showed the same chlorine removability as the silver free PAN-ACF. It was found that the specific surface area of the silver supported PAN-ACF (SA: 800 m²/g, 920 m²/g) did not fall lower than 20000 ppm silver of ACF. The silver supported PAN-ACF (Ag: 1250--30000ppm) showed a high sterilization effect in the range of low dissolved silver content in water. These results were applied to the development of a sterilizable filter for water purifier. t Studies on the Development of Polyacrylonitr. le Based Activated Carbon Fiber. IV.

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The heat of adsorption of an alkyd resin on titanium dioxide pigments was measured to evaluate the affinity between the alkyd resin and titanium dioxide pigments.
A flow micro calorimeter (FMC) equipped with two micro syring e pumps, a sample cell and a thermister (sensitive to 10-5°C) was used. Pigment was put in the sample cell and toluene was allowed to flow in it from one pump. After a straight base line was obtained, a toluene solution of the alkyd resin was pumped into the sample cell by the other pump, and the liberated heat of adsorption (ΔH^ADS_IST) was measured. It took 40, 60m in to reach an adsorption equilibrium. The adsorbed alkyd resin was desorbed (all or partially) by pumping toluene into the sample cell. Again, the alkyd resin solution was pumped and the heat of adsorption for the second contact (ΔH^ADS_2ND) was measured. The measurement was carried out on 4 titanium dioxide pigments having different surface treatment.
Dispersibility of the pigments in the alkyd resin solution was inve stigated from the viewpoint of the heat of adsorption. The pigments with larger (ΔH^ADS_IST-H^ADS_2ND) showed higher dispersion rate and higher degree of dispersion. Contribution of the functional group s of the alkyd resin to the heat of adsorption was estimated by the calorimetry using model compounds such as ethyl benzoate, benzoic acid, ethanol and hexane. It was found that ester, hydroxyl and carboxyl groups contribute to the heat of adsorption.

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In our previous paper, a spin exchange reaction of solubilized hydrophobic radicals 2, 2, 6, 6-tetramethyl-4-myristoyloxy-1-piperidinyloxyl (MyONO) with Ni²⁺ ions bound onto SDS micellar surfaces was investigated in order to understand the dynamics of reactive species in the micellar field; the spin exchange accompanies the molecular collision between paramagnetic species. It was found out there that the dependence of the ESR linewidth of MyONO 4on the bound Ni²⁺ concentration is not the same as a linear relationship in ordinary isotropic solutions; the dependence gives the rate constant of the molecular collision. In the present paper, the spectral simulation by means of modified Bloch equations reveals that the unusual dependence is caused by a particular distribution of bound-Ni2+ ions among micelles. In addition, it is proved that a binomial distribution is the most suitable one among four distribution functions; the other three are a Poisson, a geometrical, and a Gauss-type distribution.

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Acetaldehyde and its homologues are reduced by an acid-stable NADH model compound, 9, 10-dihydro-10-methylacridine, in the presence of Lewis acids such as tin tetrachloride, titanium tetrachloride, and trimethylsilyl perchlorate in dichloromethane or chloroform at 193 K or 218 K to yield 10-methylacridinium ion and the corresponding alcohols.

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Oxidation of SO₂ in the ozone-ethylene reaction system was investigated in both the absence and the presence of water vapor by use of HCOOH as an indicator of reaction pathway. In the absence of SO₂, the yield of HCOOH increased with the increase of water vapor. On the contrary, it decreased with water vapor in the presence of SO₂, although absolute yield was much higher than that in the absence of SO₂. These phenomena are in accord with the mechanism we reported previously; the reaction proceeds via formation of the CH₂OO+SO₂ adduct. The ratio of the rate constants, k(Adduct+H₂O)/k(Adduct+SO₂) w as estimated to be 6.0x10-3.

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Quenching distances have been measured for methane, ethane, propane, buta ne, ethylene oxide, and hydrogen, respectively, for different total pressures and oxygen concentrations (Fig.1). It has been found that the values of equivalence ratio φ, which correspond to the minimum quenching distances do not much change when the pressure and/or oxygen concentration are changed. The effects of pressure and oxygen concentration on the quenching distances of methane through butane are very similar. For ethylene oxide, the effect of oxygen concentration becomes relatively small. For hydrogen, this trend is more exaggerated than for ethylene oxide. The values of reaction order and activation energy have been estimated from the changes of the minimum quenching distances (Table 1). The values estimated here for methane and hydrogen are compared with those determined from the burning velocity in the literature (Tables 2 and 3). Agreement is not good between the values estimated from the quenching distances and those obtained from the burning velocities.

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Pure chitosan was prepared from cuticle of crab shells by hydrothermal methods. The hydrothermal treatment was useful for demineralization, deproteination and deacetylation of cuticle. The hydrothermal treatment of cuticle with 2 M HC1 solution at 120 °C for 1 h brought about demineralization up to 100% (Fig.2), then the demineralized product was deproteinated and deacetylated significantly by the hydrothermal treatment with 15 M NaOH solution at 150 °C for 1 h. These processes of deproteination and deacetylation could be carried out at the same time. Furthermore, these hydrothermal treatments brought about a considerable reduction in time (Fig.4). Highly deacetylated chitosan from cuticle thus treated hydrothermally had molecular weight of about 7.4 x 10⁴.

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