bluuebunny/crossref_metadata_2025 huggingface dataset:
Conductometric Study of Ion Association between Tris(oxalato)chromate(III) and Alkali Metal Ions at Temperatures from 0 to 50 °C
Authors: Yokoyama Haruhiko , Hiramoto Toshiaki , Shinozaki Kazuteru
Published: July 2006

Conductivities for aqueous solutions of alkali metal salts of tris(oxalato)chromate(III) ([Cr(ox)3]3−) were measured at various temperatures from 0 to 50 °C. Ion-association constants (KA) between the complex ion and alkali metal ions increased in the order Li+ << Na+ < K+ < Rb+ < Cs+ and had minimum values (KA(min)) at characteristic temperatures (tmin) in the observed temperature range except for the lithium ion. The appearance of minima of KA suggested the formation of contact ion pairs besides that of solvent-separated ones. The contact ion-pair formation was considered to be assisted by weak hydration of alkali metal ions and enhanced with decreasing their hydration strength. The lithium ion was presumed to form only solvent-separated ion pairs on the basis of extremely small ion-association constants. Temperature dependence of log KAfor each ion association could be represented by the equation: log KA = p(t − tmin)2 + log KA(min). A common relationship between p and tmin was found out for the ion-association systems of [Cr(ox)3]3−, [Co(NH3)6]3+, and [Co(en)3]3+ (en = ethylenediamine), and p was expressed by an empirical quadratic equation in tmin. The standard enthalpy changes of ion association (ΔHas°) at any temperature for these complex systems could be reproduced within ±0.2 kJ mol−1 by use of these equations with the experimental tmin. Hydration behavior of [Cr(ox)3]3− was also discussed based on limiting molar conductivities and their temperature dependence.
Determination of Trace Copper in Natural Waters after Selective Separation by Flotation
Authors: Ghazy Shaban E , Kabil Mohamed A
Published: July 2006

Microgram amounts of copper(II) in one liter of water are quantitatively separated selectively as copper(II) acetate with oleic acid surfactant at pH range 6.5—7.5. The floated scum is separated, after shaking for few seconds, and measured colorimetrically at 700 nm. Beer’s law is obeyed in the concentration range (0.5—5) × 10−4 mol dm−3, {3.18—31.8 ppm of copper(II)}. Alternatively, the copper in the scum is eluted by nitric acid 0.1 mol dm−3, completed to the suitable volume required for copper atomic absorption measurement at 324.7 nm with 1 ppm detection limit. The different factors affecting the selective flotation of copper(II) have been studied. It has been found that iron(III) seriously depresses the flotation efficiency. The flotation mechanism is discussed. The method of the separation and determination is rapid and applicable to 50 ppb copper(II) concentration level in natural waters.
Dithionite as a New Reductant in the Thiocyanate Method for the Spectrophotometric Determination of Molybdenum
Authors: Dass Rameshwar , Mehta Jaswant Ram
Published: July 2006

Sodium dithionite has been recommended as a new reductant in the thiocyanate method for the spectrophotometric determination of molybdenum. The study is based on prior extraction of molybdenum(VI)–thiocyanate species in ethyl acetate from 0.8 mol dm−3 HCl medium followed by reduction of the complex with dithionite in the organic extract. The orange yellow color so obtained is measured at λmax 468 nm against a reagent blank. The 1 : 5 (Mo : SCN) complex is stable for 1 h in ethyl acetate and obeys Beer’s law over the concentration range 0—2.6 ppm of molybdenum (optimum range for accurate determination is 0.7—2.5 ppm). The molar absorptivity and Sandell sensitivity of the complex are 1.79 × 104 dm3 mol−1 cm−1 and 0.0053 μg Mo cm−2, respectively. The relative standard deviation for nine replicate determinations of 2 μg Mo cm−3 is ±1.1%. Of the tested 40 cations and 24 anions including complexing agents only thiourea interferes in the procedure. The method is sensitive and highly selective. It is applicable to the determination of molybdenum in steels and flue dust samples with satisfactory results.
Hydration to the Poly(oxyethylene) Derivative Complexes of Alkali Metal Ions and Barium Ion in 1,2-Dichloroethane
Authors: Kikuchi Yoichi , Kubota Mitsuru , Suzuki Toshio , Sawada Kiyoshi
Published: July 2006

A series of poly(oxyethylene) derivatives (POE compound) complexes of alkali metal and barium ions were extracted into 1,2-dichloroethane (1,2-DCE) by forming ion-pairs with picrate ion. Water molecules were coextracted into 1,2-DCE with the ion-pairs. The mean number of water molecules bound to the POE compound, XH2O,S, and its complex, XH2O,comp, in water saturated with 1,2-DCE was determined by means of aquametry. The XH2O,S value increases with the increase in the number of the oxyethylene units (EO unit) of the POE compound. The XH2O,comp value decreases in the order Li+ > Na+ > K+ ≈ Rb+ ≈ Cs+ in any POE compound systems, and increases with the number of EO units of the POE compounds for a given metal ion. These results are interpreted by the hypothesis that the water molecules bound to the complex are those hydrated to the central metal ion, and the hydrated metal ion is surrounded by the EO chain with a helical conformation in the complex. The large number of water molecules are coordinating to the lithium ion complexes and bring about a serious distortion in the helical structure of the complexes. Because of the ion-pair formation with two picrate ions, the XH2O,comp values of barium ion complexes are smaller than those of potassium ion complexes.
Kinetics and Mechanisms of a New Type of Catalysis in the Activated Carbon for the Ligand-Substitution Reaction between the Inert Complex [Co(NH3)5Cl]2+ and EDTA in Aqueous Media
Authors: Kimura Masaru , Miyamoto Ikuko
Published: July 2006

The ligand-substitution reaction of the pentaamminechlorocobalt(III) ion, [Co(NH3)5Cl]2+, with ethylenediaminetetraacetate (EDTA) (which denotes all the forms of EDTA, i.e. edta4−, Hedta3−, H2edta2− etc.) occurred efficiently in the presence of the activated carbon (AC) in aqueous media of pH 4.7, where the AC acts as a catalyst of the electron-transfer mediator. The ligand-substitution reaction constitutes a chain reaction composed of an AC and AC+ cycle, where the substitution reaction is initiated by the electron-transfer from AC to the cobalt(III) complex. The formation rate of [Co(edta)]− by the substitution reaction between [Co(NH3)5Cl]2+ and EDTA was of the first-order with respect to concentrations of not only [Co(NH3)5Cl]2+ but also AC, and was of the zero-order with respect to the EDTA concentration. Further, the rate was irrespective of the dissolved oxygen O2. The substitution reaction was always quantitative, i.e. [[Co(NH3)5Cl]2+]decreased = [[Co(edta)]−]formed at any reaction time up to completion of reaction.
Physicochemical Perturbation of α-Linolenic Acid Related to Cell Proliferation
Authors: Fukui Hiroki , Sato Toshinori , Sunamoto Junzo
Published: July 2006

The influence of fatty acids, α-linolenic acid (ALA), and linoleic acid (LA), on lipid membrane dynamics and cell proliferation was investigated. Electron-spin resonance measurements with 2-hexyl-2-(10-methoxycarbonyldecyl)-4,4-dimethyl-3-oxazolidinyloxyl revealed that the penetration of ALA or LA into the liposomal membrane causes an increase in the membrane fluidity and a decrease in the phase-transition temperature of the lipid membrane. When human colon cancer cells (RPMI4788 and BM314) and normal mouse fibroblast (L-cell) were incubated with ALA, the membrane fluidity of the cancer cells significantly increased over that of normal cells. ALA made the cancer cell membrane more fluid than did LA. When ALA was administered at a concentration of 40 μg ml−1, it showed a strong cytotoxicity against the cancer cells, but not to the normal cells. On the other hand, LA (up to 80 μg ml−1) rather promoted growth of the cancer cells. These results seem able to be interpreted as an aspect of the selective cytotoxicities of ALA.
Transformation of Alkyl N-(Vinyloxy)benzimidates to Alkyloxazoles. Mechanism and Extension
Authors: Yokoyama Masataka , Menjo Yasuhiro , Ubukata Makoto , Irie Masakazu , Watanabe Mikari , Togo Hideo
Published: July 2006

Transformation of alkyl N-(vinyloxy)benzimidates to alkyloxazoles proceeds through the intermediates: a charge-separated 1,2-oxazetidine derivative and then 1-hydroxy-2-[[methylthio(phenyl)methylene]imino]maleic acid diester, while their photochemical transformation takes place via a concerted [1,3] sigmatropic shift. As the extension of this reaction, the preparation of the precursor proposed for virginiamycin M2 synthesis and the reaction of N-analogs of alkyl N-(vinyloxy)benzimidates are described.
Solvent Effects on the Solvolysis of Benzyl p-Toluenesulfonates
Authors: Fujio Mizue , Susuki Toshihiro , Goto Mutsuo , Tsuji Yutaka , Yatsugi Ken-ichi , Saeki Yoshihiro , Kim Sung Hong , Tsuno Yuho
Published: July 2006

Solvolysis rates of benzyl p-toluenesulfonate were determined in a wide variety of solvents. The solvent effects were analyzed based on the Winstein–Grunwald equation. The solvent effect on benzyl solvolysis failed to give a single linear correlation with the 2-adamantyl YOTs parameter. The lower response to the solvent polarity and the pattern of dispersion for each binary solvent series can be qualitatively interpreted in terms of nucleophilic solvent assistance. The Winstein–Grunwald analysis gave m = 0.67 and l = 0.36, but with less satisfactory precision. The use of the polarity scale Yneo derived from 2-methyl-2-phenylpropyl solvolysis in place of YOTs gave an improved correlation. A solvent polarity scale Yneo is better applicable to benzyl solvolysis than 2-adamantyl-based YOTs, since the former is compatible with the entire π-delocalization of cationic charge between aryl ring and the reaction center in the transition state.
Stereochemical Control in Microbial Reduction. XXIII. Thermal Treatment of Bakers’ Yeast for Controlling the Stereoselectivity of Reductions
Authors: Kawai Yasushi , Kondo Shin-ichi , Tsujimoto Munekazu , Nakamura Kaoru , Ohno Atsuyoshi
Published: July 2006

The diastereoselectivity in a bakers’ yeast reduction of various alkyl 2-alkyl-3-oxoalkanoates can be controlled by a thermal treatment of the yeast in the presence of methyl vinyl ketone. Pretreated bakers’ yeast gives the corresponding (2R,3S)-hydroxy esters selectively. Two β-keto ester reductases, named l-enzyme-1 and l-enzyme-2, are actual reductants of intact bakers’ yeast reduction. The thermal stability and inhibition constants of the purified enzymes can dictate the stereochemical outcome of pretreated bakers’ yeast reductions.
Aerobic Enantioselective Epoxidation of Unfunctionalized Olefins Catalyzed by Optically Active Salen–Manganese (III) Complexes
Authors: Yamada Tohru , Imagawa Kiyomi , Nagata Takushi , Mukaiyama Teruaki
Published: July 2006

Enantioselective epoxidation of unfunctionalized olefins is achieved by the combined use of molecular oxygen and pivalaldehyde in the presence of a catalytic amount of optically active Mn(III)–salen complexes. N-Alkylimidazoles are effective axial ligands to produce optically active epoxides with high enantioselectivities in the present procedure; that is, 1,2-dihydronaphthalene derivatives and 2,2-dialkyl-2H-chromene derivatives are converted into the corresponding optically active epoxides with 60—92% enantiomeric excess. The key intermediates in the present aerobic epoxidation are also discussed.
Nickel- and Palladium-Catalyzed Aldol-Type Condensation by Enol Esters
Authors: Masuyama Yoshiro , Sakai Tatsuya , Kato Takeshi , Kurusu Yasuhiko
Published: July 2006

PdCl2(PhCN)2–SnCl2, bis(1,5-cyclooctadiene)nickel(0) [Ni(cod)2]/PPh3–Zn, NiBr2(PPh3)2–Zn, or Pd(OAc)2/PPh3–Zn catalytic systems induced aldol-type condensation of isopropenyl acetate with aldehydes to produce 4-substituted (E)-3-buten-2-ones. PdCl2(PhCN)2–SnCl2 was utilized in the aldol-type reaction with any arenecarbaldehyde, bearing either an electron-donating group or an electron-withdrawing group, at 50 °C in acetonitrile. Catalytic systems using zinc, in particular Ni(cod)2/PPh3–Zn, exhibited some high chemoselectivities at 60 °C in dioxane: (1) an aldehyde only reacted in the presence of an internal ester or ketone, (2) olefinic aldehydes only reacted in the presence of saturated aliphatic aldehydes, (3) reactivity in the condensation with substituted benzaldehydes is the inverse of that in usual nucleophilic addition to carbonyl compound, and (4) 2-methoxybenzaldehyde only reacted in the presence of 4-methoxybenzaldehyde. Using PdCl2(PhCN)2–SnCl2, Ni(cod)2/PPh3–Zn, or Pd(OAc)2/PPh3–Zn, cyclic enol ester, namely 5-methyl-2(3H)-furanone also caused aldol-type reaction with carbonyl compounds. The reaction with Ni(cod)2/PPh3–Zn or Pd(OAc)2/PPh3–Zn at 60 °C in dioxane selectively produced 5-substituted 4-acetyl-2(5H)-furanones via dehydrogenation of γ-substituted β-acetyl-γ-butyrolactones.
Oxidative Coupling of Methane over Calcined Coral-Sands: Their Catalytic Property and Comparison with Other Natural Calcium Carbonates
Authors: Yamagata Nobutsugu , Usami Ken , Okazaki Susumu
Published: July 2006

Coral sands calcined at high temperatures of 800 and 1000 °C were found to be an effective catalyst for the oxidative coupling of methane to C2 hydrocarbons, especially with high selectivity. The coral-sand catalyst was almost composed of calcium oxide; however, it also contained small amounts of Na, Sr, Mg ions etc., and had a characteristic structure with many small pores of 2—8 μm in diameter, which were formed during calcination. In order to investigate the role of their components in C2 formation, nine kinds of catalysts were prepared from other natural calcium carbonates, such as turbo shell, short-necked clam shells, and marbles; their catalytic properties were compared with that of the coral-sand catalyst. Consequently, it seemed that the C2 yield was related to the bulk and surface concentrations of sodium in the catalyst, while the maximum-C2 selectivity at 700—800 °C was related to those of strontium. The catalysts of corals and coral sands showed the highest maximum-C2 selectivity as well as the highest strontium-content (about 1.2wt%). It was considered that the strontium ions are well-dispersed in the catalyst and that they enhance the basicity in combination with sodium ions (main active species), leading to the high C2 selectivity.
Contribution of the First-Order Differential of the Potential to the Pressure-Induced Frequency Shift of the Intramolecular Vibrations in Crystal
Authors: Kawano Hiroshi , Maehara Masayoshi , Nibu Yoshinori , Shimada Hiroko , Shimada Ryoichi
Published: July 2006

The pressure-induced frequency shift of the intramolecular vibrations in crystal was calculated using an atom–atom type intermolecular potential. The calculation indicates that the contribution of the first-order differential of the potential to the frequency shift is very small when the potential is well approximated.
Electrocatalytic Reduction of Oxygen by Viologen-Linked Polypyrrole Coated on Glassy Carbon Electrode
Authors: Kijima Masashi , Sakawaki Akira , Sato Takeo
Published: July 2006

Viologen linked-N-substituted pyrroles were prepared and polymerized by electrochemical oxidation on glassy carbon, giving viologen-modified electrodes. The electrons were transferred from the modified electrode to O2 through the viologen moiety. The modified electrode worked as reactive electrodes for the selective electrocatalytic reduction of O2 to H2O2.
Synthesis of N-(9-Oxo-7-phenyl-9H-pyrano[2,3-g]benzothiazol-2-yl)benzamides from 6-Aminoflavone
Authors: Rao Mantripragada Narayana , Sambaiah Thota , Krupadanam Gazula Levi David , Srimannarayana Gotety
Published: July 2006

6-Aminoflavone (1) was treated with aroyl isothiocyanate in acetone at reflux temperature yields N-aroyl-N′-(2-phenyl-4-oxo-4H-[1]benzopyran-6-yl)thioureas (2). The products obtained on reaction of 2 with PCl5 in POCl3 medium leads to N-(9-oxo-7-phenyl-9H-pyrano[2,3-g]benzothiazol-2-yl)benzamides (4). The structures of the compounds synthesized were established by analytical and spectral data.
Synthesis of Phenylacetic Acid via Carbonylation of Benzyl Chloride in the Presence of a Water-Soluble Complex, [PdCl2{PPh2(m-C6H4SO3Na)}2], and Surfactants under Two-Phase Conditions
Authors: Okano Tamon , Hayashi Tetsuji , Kiji Jitsuo
Published: July 2006

The addition of surfactants such as n-C7H15SO3Na or n-C7H15COONa is effective in acceleration of the carboxylation of benzyl chloride using a water-soluble catalyst, [PdCl2{PPh2(m-C6H4SO3Na)}2], in an aqueous NaOH–heptane solution. Phenylacetic acid is easily isolated from the aqueous layer in high yields. However, the addition of n-C7H15SO3Na has no effect on the carboxylation using hydrophobic catalysts, [PdCl2(PPh3)2] and [Pd(PPh3)4], under the two phase conditions.
Photosensitized Electron-Transfer Reaction of 3-Aryl-2-methyloxaziridine: Direct Deoxygenation from the Isomeric Arylnitrone
Authors: Iwano Yasunori , Kawamura Yasuhiko , Miyoshi Hiroki , Yoshinari Toshifumi , Horie Tokunaru
Published: July 2006

Photosensitized electron-transfer reactions of 3-aryl-2-methyloxaziridines gave mainly the corresponding benzaldehydes, whereas the isomeric nitrones gave imines as well as aldehydes. Deoxygenation of the nitrone occurred via the nitrone cation radical under the reaction conditions. An aryl substituent effect on the reaction and isomerizations of both cation radicals are also discussed.
Crystal Structures of TMEO-TTP and (TMEO-TTP)[AuBr2]·THF
Authors: Misaki Yohji , Nishikawa Hiroyuki , Yamabe Tokio , Mori Takehiko , Inokuchi Hiroo
Published: July 2006

The molecular and crystal structures of the title compounds, where TMEO-TTP is 2-[4,5-bis(methylthio)1,3-dithiol-2-ylidene]-5-[4,5-ethylenedioxy-1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiapentalene, have been investigated by X-ray crystal structure analysis. The BDT-TTP skeleton of neutral TMEO-TTP adopts a slightly flat chair conformation. The crystal has a columnar structure, in which the molecules dimerize in a head-to-tail manner. Several S···S contacts shorter than the sum of the van der Waals radii (3.70 Å) are observed along the transverse direction. (TMEO-TTP)[AuBr2]·THF also has a columnar structure in which the donor molecules dimerize. However, “side-by-side” interaction between the donors is prohibited because the AuBr2 anions and the THF molecules are located at the sides of the donor molecules.
Interaction of Sodium 4′-(Butylamino)azobenzene-4-sulfonate with Octyl Methyl Sulfoxide in Adsorbed Film and Micelle
Authors: Tanaka Fudeko , Harada Yuzo , Ikeda Norihiro , Aratono Makoto , Motomura Kinsi
Published: July 2006

The surface tension of the aqueous solution of sodium 4′-(butylamino)azobenzene-4-sulfonate (SBAS) and octyl methyl sulfoxide (OMS) mixture was measured as a function of the total molality at various compositions and at 298.15 K under atmospheric pressure. The experimental results were analyzed by applying the thermodynamic relations. The phase diagrams of adsorption and micelle formation were found to suggest that SBAS and OMS molecules interact attractively with each other to form a negative azeotropic mixture in the adsorbed film at a low surface tension and in the micelle. These findings were qualitatively similar to those of the system of SBAS and 2-(octylsulfinyl)ethanol (OSE) and confirmed our conclusion that the strong interaction of dye and nonionic surfactant molecules at the interface may be the one of reasons why a nonionic surfactant acts as the leveling agent in dyeing process.
Mixing Schemes and Liquid–Solid Phase Diagram in the Water-Rich Region of Aqueous 2-Butoxyethanol
Authors: Koga Yoshikata , Tanaka Toshiaki , Atake Tooru , Westh Peter , Hvidt Aase
Published: July 2006

Liquid–solid phase diagram was determined in the water-rich region of aqueous 2-butoxyethanol. A solid addition compound was suggested with the composition = 0.0260, which melts incongruently at 269.5 K. The mixing scheme boundary separating two regions in the single liquid phase domain (Chem. Phys. Lett., 217, 245 (1994)) was found to cross the incongruent melting point of the above solid addition compound.
Determination of the Critical Micelle Concentrations and Microviscosity with a Fluorescence Probe, Auramine
Authors: Miyagishi Shigeyoshi , Kurimoto Hirotaka , Ishihara Yuuhichi , Asakawa Tsuyoshi
Published: July 2006

A new method based on the fluorescence intensity of bis[4-(dimethylamino)phenyl]methanimine (auramine) was proposed in order to determine the critical micelle concentration (cmc). The cmc values of the following surfactants were determined by the present method, and were compared with those by a surface-tension method. The nonionic surfactants used were homogeneous polyethylene glycol monododecyl ether (C12E5, C12E6, C12E7, and C12E8) and N-acyl-N-methylglucamine (MEGA-7, -8, -9, -10, and -12). The cationic surfactants were dodecyltrimethylammonium chloride and bromide (DTAC, DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium chloride and bromide (CTAC, CTAB). The potassium salt of N-acylalanines, the sodium salt of N-acylvalines, and sodium dodecyl sulfate were used as anionic surfactants. The cmcs measured by both methods were in good agreement with each other in all systems of surfactants used. The effects of added salt, temperature, and size of the acyl group on the microviscosity were also estimated.
Photochemical Reaction of Trichloroacetic Acid with Diphenylamine and Its Analytical Application
Authors: Pal Anjali
Published: July 2006

A method for the determination of trichloroacetic acid (TCA) in a simple spectrophotometric way has been described. It is based on the photochemical reaction of TCA with diphenylamine (DPA) which forms a green colored product (λmax: 652 nm). The relative standard deviation for all measurements is <7%. A linear calibration graph is obtained in the concentration range of 610 to 2875 ppm with a correlation coefficient 0.990. The method is simple, rapid and does not require any costly and hazardous chemical. The effect of solvent, reagent concentration, time of irradiation etc. have been discussed. Extraction of TCA from contaminated water or urine with upto 10 fold increase in concentration followed by photochemical reaction and absorption measurement showed good correlation with the theoretical value. The interference by chloroacetic acid (MCA), dichloroacetic acid (DCA), chloroform (CHCl3), carbon tetrachloride (CCl4), trichloroethylene (TCE), and perchloroethylene (PCE) have also been studied.
Magnetochemical and Molecular Orbital Analyses on Lithium Electrochemically Doped Non-Graphitizable Carbon Electrode of Lithium Ion Rechargeable Batteries
Authors: Tanaka Koichi , Ata Masafumi , Kimura Hitoshi , Imoto Hiroshi
Published: July 2006

The electronic characteristics of electrochemically doped lithium in non-graphitizable carbon, which was obtained by heat-treating polyfurfuryl alcohol (PFA-C) and was used as the negative electrode of lithium ion rechargeable batteries, were examined with the aid of 7Li solid-state nuclear magnetic resonance (NMR) and electron spin resonance (ESR). In order to clarify how lithium is incorporated in the carbon electrode, discrete variational-Xα (DV-Xα) molecular-orbital calculations were also performed on a model system. These experimental and theoretical results suggest that the lithium doped in the carbon exists in a non-metallic state with low electron density as compared to the ionic crystal, and that the unpaired electrons in the lithium doped carbon are delocalized at the peripheral carbon domains of the system. This was theoretically supported by the fact that the singly occupied molecular orbital (SOMO) of the lithium doped carbon is lower by 5.388 eV than the orbital localized predominantly on lithium 2s, and that the system is stabilized by electron donation from lithium to the carbon.
Structure and State-Energy Relationship of Photo-Excited Cu(I) Complex
Authors: Shinozaki Kazuteru , Kaizu Youkoh
Published: July 2006

Excited [CuI(dmphen)2]+ (dmphen = 2,9-dimethyl-1,10-phenanthroline) was studied in terms of its molecular structure. The MLCT (metal-to-ligand charge-transfer) transition energy and phosphorescence lifetime of the copper(I) complex in the solid state were reduced with diminishing the dihedral angle between two dmphen ligands. The results of a DV-Xα molecular orbital calculation were in good agreement with the spectroscopic results. In solution, the non-luminous character of [CuI(phen)2]+ (phen = 1,10-phenanthroline), which had no steric-hindered methyl groups retarding the flattening motion, was explained from lowering the lowest excited MLCT state due to a drastic distortion by the photoexcitation.
Photoracemization of Ruthenium(II) Complexes with 2,2′-Bipyridine and Di-2-pyridylamine
Authors: Nagao Noriharu , Mukaida Masao , Miki Eiichi , Mizumachi Kunihiko , Ishimori Tatujiro
Published: July 2006

The emission lifetime (τobs) and quantum yield of photoracemization (φrac) for a series of complexes, [Ru(bpy)n(Hdpa)3−n]2+ (n = 0—3), were studied in aqueous solution at temperatures of between 20 and 60 °C. The values of τobs of [Ru(bpy)2(Hdpa)]2+ were found to vary around 80—200 ns, depending upon temperature, while [Ru(bpy)(Hdpa)2]2+ and [Ru(Hdpa)3]2+ did not emit at the temperature studied. The photoracemization reactions of [Ru(bpy)3]2+, [Ru(bpy)2(Hdpa)]2+, [Ru(bpy)(Hdpa)2]2+, and [Ru(Hdpa)3]2+ were thermally activated with φrac of (0.1—1.6) × 10−3, (0.5—6) × 10−3, (0.04—0.22) × 10−3, and (0.1—0.25) × 10−3, respectively, depending upon the conditions. The photochemical behavior of [Ru(bpy)2(Hdpa)]2+ was explained by a set of excited states, which was assumed to include the 3d–π*bpy, 3d–d*, and 3n–π*bpy states. The reactive state, the 3d–d* state, was thermally yielded from the 3d–π*bpy state. The displacement of a bpy ligand by an Hdpa ligand made the quantum yield of the formation of the 3d–d* state from the 3d–π*bpy state (φd–d) smaller, and the intrinsic quantum yield of photoracemization (φrac(d–d)) larger. The fact that φrac for [Ru(bpy)(Hdpa)2]2+ and [Ru(Hdpa)3]2+ was smaller than that for [Ru(bpy)3]2+ and [Ru(bpy)2(Hdpa)]2+ could be interpreted by assuming that the displacement of the bpy ligand by the Hdpa ligand diminished the quantum yield of the formation of the 3d–d* state from the 3d–π*bpy or 3d–π*Hdpa states considerably, due to the bypath from the 3d–π*bpy or 3d–π*Hdpa states through the 3nHdpa–π*bpy or 3nHdpa–π*Hdpa states to the ground state.
Intramolecular Ligation of Carbonyl Oxygen to Central Zinc in Synthetic Oligopeptide-Linked Zinc-Porphyrins
Authors: Tamiaki Hitoshi , Kiyomori Ayumu , Maruyama Kazuhiro
Published: July 2006

Oligopeptide-linked zinc-porphyrins were prepared (oligopeptide = –Phem–Alan–OMe and porphyrin = 5,15-diaryl-2,3,7,8,12,13,17,18-octaethylporphyrin). 1H NMR, IR, visible, and CD spectra of the synthetic molecule in a chlorinated methane (CDCl3 or CH2Cl2) showed that the carbonyl oxygen of the N-terminal amino acid of the linked peptide should ligate the central zinc metal in the molecule as the axial ligand to form a pentacoordinated zinc-porphyrin. The coordination of the zinc with the peptide framework changed the optical and electrical properties, indicating that such ligation might control the reactivity in biological metallotetrapyrrole–protein systems as well as the coordination to the peptide residue.
Convenient Synthesis of 1α,25-Dihydroxyvitamin D3 from Vitamin D2
Authors: Takahashi Minokazu , Sakakibara Yasumasa
Published: July 2006

(1S,6R)-1-Acetoxy-6-(1,3-benzodithiol-2-yloxy)-3,5-cyclovitamin D2 (7) was synthesized from vitamin D2 by five steps. The new compound 7 was ozonized regioselectively and subsequently reduced, leading to (7E)-(1S,3S,5R,6R)-1-acetoxy-6-(1,3-benzodithiol-2-yloxy)-3,5-cyclo-9,10-seco-23,24-dinor-7,10(19)-choladien-22-ol (11). The alcohol 11 obtained as a key intermediate was tosylated, iodinated, and coupled with 2-methyl-4-phenylsulfonyl-2-(tetrahydropyranyloxy)butane to give (1S,6R)-1-hydroxy-6-(1,3-benzodithiol-2-yloxy)-23-phenylsulfonyl-25-tetrahydropyranyloxy-3,5-cyclovitamin D3 (16). By desulfonylation and hydrolysis of the compound 16 1α,25-dihydoxyvitamin D3 was obtained selectively.
Synthesis and Properties of Conjugated Porphyrins with a Diacetylene Spacer
Authors: Imahori Hiroshi , Higuchi Hiroyuki , Matsuda Yoshihiko , Itagaki Ayano , Sakai Yoshie , Ojima Jûro , Sakata Yoshiteru
Published: July 2006

A series of (porphyrin)–(C≡C)2–C6H4–R1 (R1 = NO2, H, Me, and OMe) were synthesized by the oxidative coupling of ethynyl porphyrins and phenylacetylenes in the presence of copper(II) acetate in pyridine. Electronic and electrochemical spectra of the compounds with R1 = H, Me, and OMe are quite similar, while pronounced change was observed for the compound with R1 = NO2, especially for the meso-substituted one, indicating that intramolecular charge transfer is responsible for the difference.
Stereoselective Addition of Organoaluminium or Organomanganese Reagents to α-Formyl Amides or α-Methyl-Substituted β-Keto Amides
Authors: Taniguchi Masahiko , Fujii Hideaki , Oshima Koichiro , Utimoto Kiitiro
Published: July 2006

Treatment of α-formyl amides with RAlCl2 or PhAlCl2 provided threo-α-alkyl-substituted β-hydroxy amides under high stereocontrol. The method was successfully applied to the selective addition of alkyl group to α-methyl-substituted β-keto amides or esters. Treatment of α-methyl-β-keto amides or α-methyl-β-keto esters with trialkylaluminium or alkylmanganese halide afforded the corresponding erythro (or threo) α-methyl-substituted β-hydroxy amides or α-methyl-substituted β-hydroxy esters with high stereoselectivity.
Titanium(III)-Induced Transformation of Hydroxylamines to Imines or Secondary Amines
Authors: Kodera, Yoichi , Watanabe Shoji , Imada Yasushi , Murahashi Shun-Ichi
Published: July 2006

N,N-Disubstituted and cyclic hydroxylamines can be converted into the corresponding imines efficiently upon treatment with anhydrous titanium trichloride in THF at room temperature. Similar treatment of N-allylhydroxylamines with anhydrous titanium trichloride gives 1-azadienes, which are versatile synthetic intermediates for aza-Diels–Alder reactions. On the other hand, the same hydroxylamines can be converted into the corresponding secondary amines upon treatment with aqueous titanium trichloride in methanol. It is noteworthy that optically active hydroxylamines, which have chirality at the α-position to nitrogen, can be converted into optically active secondary amines without loss of chirality. Dihydro-2(1H)-quinolinones can be prepared upon treatment of 1-hydroxy-3,4-dihydro-2(1H)-quinolinones with aqueous titanium trichloride. The substrates of N,N-disubstituted and cyclic hydroxylamines can be prepared readily upon treatment of nitrones with nucleophiles. Since nitrones can be prepared by metal-catalyzed oxidations of secondary amines with hydrogen peroxide, the present titanium(III)-promoted reaction of hydroxylamines will provide a convenient method for the synthesis of either α-substituted imines or amines from secondary amines.
Ruthenium–Niobia Interaction in Nb2O5-Supported and Nb2O5-Modified Ru Catalysts
Authors: Kunimori Kimio , Shindo Hisakazu , Nishio Daisuke , Sugiyama Takeshi , Uchijima Toshio
Published: July 2006

The effect of H2 reduction treatments on H2 chemisorption, ethane hydrogenolysis, and CO hydrogenation over Nb2O5-supported and Nb2O5-modified Ru catalysts has been studied to elucidate the nature of the metal-oxide interaction, and the results are compared with those of a SiO2-supported Ru catalyst. The Ru/Nb2O5 and Nb2O5–Ru/SiO2 catalysts after high-temperature reduction at 500 °C showed a typical SMSI behavior, while a specific Ru–niobia interaction, which resulted in a higher ethane hydrogenolysis activity, was induced even after low-temperature reduction at 200 °C.
Physical Properties of 3-s-Butylsydnone
Authors: Sasaki Yukio , Komiya Ichiro , Handa Minoru
Published: July 2006

The physical properties of 3-s-butylsydnone at various temperatures were investigated by dielectric constant, refractive index, density, and viscosity measurements. These physical constants were compared with those of other 3-alkylsydnones. Although the differences in the dielectric constant, refractive index and density between 3-butylsydnone and 3-s-butylsydnone were relatively small, the viscosity of 3-s-butylsydnone became particularly larger than that of 3-butylsydnone at lower temperatures.
Synthesis and Properties of Dinuclear Copper(II) Complexes Containing Dinucleating Ligands with Imidazole Nitrogen and Two Exogenous Bridging Ligands
Authors: Nakao Yasuo , Oonishi Makoto , Uzu Tomoko , Kashihara Hiroko , Suzuki Shinnichiro , Sakai Masahiro , Fukuda Yutaka
Published: July 2006

Dinuclear copper(II) complexes, [Cu2(nR)X2] (ClO4)2 (X = N3−, NCS−, and OAc−) have been synthesized and characterized, where nR = N,N,N′,N′-tetrakis[(1-methyl-2-benzimidazolyl)methyl]-1,3-diaminopropane (3Me), N,N,N′,N′-tetrakis[(1-ethyl-2-benzimidazolyl)methyl]-1,3-diaminopropane (3Et), N,N,N′,N′-tetrakis[(1-methyl-2-benzimidazolyl)methyl]-1,4-diaminobutane (4Me), and N,N,N′,N′-tetrakis[(1-ethyl-2-benzimidazolyl)methyl]-1,4-diaminobutane (4Et). Although a weak antiferromagnetic interactions were found for [Cu2(3Me)(NCS)2](ClO4)2·3H2O (coupling constant J = −2.1 cm−1, H = −2JS1·S2) and [Cu2(3Me)(OAc)2](ClO4)2·H2O (J = −2.0 cm−1), no exchange interaction has been observed to 4.2 K for [Cu2(3Me)(N3)2](ClO4)2·H2O. The Electrochemistry of these complexes in N,N-dimethylformamide showed two electron reductions at +210 — −30 mV vs. Ag–AgCl (Cu2+–Cu2+ → Cu+–Cu+).
The Wittig Rearrangement of Chiral S-Methyl Phosphinothioates Promoted by Direct Deprotonation with Lithium Dialkylamides
Authors: Kawashima Takayuki , Kojima Satoshi , Inamoto Naoki
Published: July 2006

Sequential treatment of S-methyl (t-butyl)phenyl- or (1-naphthyl)phenylphosphinothioates with lithium dialkylamides at −78 °C and then with alkyl halides at 0 °C—r.t. gave the corresponding (alkylthiomethyl)phosphine oxides, the Wittig rearrangement products, in moderate to good yields along with small amount of their overreacted α-alkylated products. The corresponding alkylphosphine oxide was obtained only in the reaction of naphthyl derivative. Optically active Wittig rearrangement products were given in 82 and 78% optical yields, respectively.
Catalytic and Thermal Behavior of Cerium Oxide Supported onSiO2 and Al2O3 for Methane Combustion
Authors: Haneda Masaaki , Mizushima Takanori , Kakuta Noriyoshi , Ueno Akifumi
Published: July 2006

CeO2/SiO2 and CeO2/Al2O3 catalysts oxidized at 1173 K in O2 stream were employed to investigate the catalytic activity for methane combustion and the behavior of CeO2 on supports by the oxidation at 1173 K. CeO2/SiO2 catalyst gave a poor catalytic activity by comparison with that of CeO2/Al2O3 catalyst. The crystallite size of CeO2 of the silica catalyst was found to be 1.5 times larger. In addition, Auger Electron Spectroscopy (AES) analysis after the oxidation at 1173 K proved that cerium species existed on and within the silica support. We conclude that the low surface density of CeO2 might contribute to the poor activity of CeO2/SiO2 catalyst for methane combustion.
Financial Asset Returns, Direction-of-Change Forecasting, and Volatility Dynamics
Authors: Christoffersen Peter F. , Diebold Francis X.
Published: July 2006

We consider three sets of phenomena that feature prominently in the financial economics literature: (1) conditional mean dependence (or lack thereof) in asset returns, (2) dependence (and hence forecastability) in asset return signs, and (3) dependence (and hence forecastability) in asset return volatilities. We show that they are very much interrelated and explore the relationships in detail. Among other things, we show that (1) volatility dependence produces sign dependence, so long as expected returns are nonzero, so that one should expect sign dependence, given the overwhelming evidence of volatility dependence; (2) it is statistically possible to have sign dependence without conditional mean dependence; (3) sign dependence is not likely to be found via analysis of sign autocorrelations, runs tests, or traditional market timing tests because of the special nonlinear nature of sign dependence, so that traditional market timing tests are best viewed as tests for sign dependence arising from variation in expected returns rather than from variation in volatility or higher moments; (4) sign dependence is not likely to be found in very high-frequency (e.g., daily) or very low-frequency (e.g., annual) returns; instead, it is more likely to be found at intermediate return horizons; and (5) the link between volatility dependence and sign dependence remains intact in conditionally non-Gaussian environments, for example, with time-varying conditional skewness and/or kurtosis.
Strategic Commitments for an Optimal Capacity Decision Under Asymmetric Forecast Information
Authors: Özer Özalp , Wei Wei
Published: July 2006

We study the important problem of how to assure credible forecast information sharing between a supplier and a manufacturer. The supplier is responsible for acquiring the necessary capacity before receiving an order from the manufacturer who possesses private forecast information for her end product. We address how different contracts affect the supplier’s capacity decision and, hence, the profitability of the supplier and the manufacturer. We fully develop two contracts (and provide explicit formulae) to enable credible forecast information sharing. The first is a nonlinear capacity reservation contract under which the manufacturer agrees to pay a fee to reserve capacity. The second is an advance purchase contract under which the manufacturer is induced to place a firm order before the supplier secures the component capacity used to build the end product. These contracts serve a strategic role in information sharing. The capacity reservation contract enables the supplier to detect the manufacturer’s private forecast information, while the advance purchase contract enables the manufacturer to signal her forecast information. We show that channel coordination is possible even under asymmetric forecast information by combining the advance purchase contract with an appropriate payback agreement. Through our structural and numerical results we also show that the degree of forecast information asymmetry and the risk-adjusted profit margin are two important drivers that determine supply chain efficiency and which contract to adopt.
On Precautionary Policies
Authors: Barrieu Pauline , Sinclair-Desgagné Bernard
Published: July 2006

In the United States and most industrialized countries, regulatory policies pertaining to food safety, occupational health, and environmental protection are (according to laws and statutes) science based. The complexity of some ecosystems and new technologies, however, makes it increasingly necessary to deal with situations where scientists cannot yet provide a definite picture. In this context, a widely invoked (but debated) rule, known as the Precautionary Principle, says to address potential hazards right away with preventive measures. We develop an intuitive formalization of this rule, which allows us to infer what an appropriate precautionary policy should do. Implications for resource conservation and the regulation of technological risks are then explored.
Agent Competition Double-Auction Mechanism
Authors: Chu Leon Yang , Shen Zuo-Jun Max
Published: July 2006

This paper proposes an agent competition double-auction mechanism to simplify decision making and promote transactions for the customer-to-customer marketplaces. Under the proposed double-auction mechanism, bidding one’s true valuation (private information) is the best strategy for each individual buyer and seller even when shipping costs and sales taxes are different across various possible transactions. The proposed mechanism also achieves budget balance and asymptotic efficiency. Furthermore, these results not only hold for an environment where buyers and sellers exchange identical commodities, but also can be extended to an environment with multiple substitutable commodities.
The management of failed ankle replacement
Authors: Kotnis R. , Pasapula C. , Anwar F. , Cooke P. H. , Sharp R. J.
Published: July 2006

Advances in the design of the components for total ankle replacement have led to a resurgence of interest in this procedure.

Between January 1999 and December 2004, 16 patients with a failed total ankle replacement were referred to our unit. In the presence of infection, a two-stage salvage procedure was planned. The first involved the removal of the components and the insertion of a cement spacer. Definitive treatment options included hindfoot fusion with a circular frame or amputation. When there was no infection, a one-stage salvage procedure was planned. Options included hindfoot fusion with an intramedullary nail or revision total ankle replacement. When there was suspicion of infection, a percutaneous biopsy was performed. The patients were followed up for a minimum of 12 months.

Of the 16 patients, 14 had aseptic loosening, five of whom underwent a revision total ankle replacement and nine a hindfoot fusion. Of the two with infection, one underwent fusion and the other a below-knee amputation. There were no cases of wound breakdown, nonunion or malunion.

Management of the failed total ankle replacement should be performed by experienced surgeons and ideally in units where multidisciplinary support is available. Currently, a hindfoot fusion appears to be preferable to a revision total ankle replacement.
Effectiveness of commercially-available antibiotic-impregnated implants
Authors: Wenke J. C. , Owens B. D. , Svoboda S. J. , Brooks D. E.
Published: July 2006

The aim of this study was to determine the effectiveness of antibiotic-impregnated implants in the prevention of bone infection. We used a model of contaminated fracture in goats to evaluate four treatment groups: no treatment, hand-made tobramycin-impregnated polymethylmethacrylate beads, commercially-available tobramycin-impregnated calcium sulphate pellets and commercially-available tobramycin-impregnated polymethylmethacrylate beads. Three weeks after intraosseous inoculation with streptomycin-resistant Staphylococcus aureus tissue cultures showed no evidence of infection in any of the antibiotic-treated groups. All of the cultures were positive in the untreated group. These results show that effective local antibiotic delivery can be obtained with both commercially-available products and with hand-made polymethylmethacrylate beads. The calcium sulphate pellets have the advantage of being bioabsorbable, thereby obviating the need for a second procedure to remove them.
Biomechanics of the Birmingham hip resurfacing arthroplasty
Authors: Ong K. L. , Kurtz S. M. , Manley M. T. , Rushton N. , Mohammed N. A. , Field R. E.
Published: July 2006

The effects of the method of fixation and interface conditions on the biomechanics of the femoral component of the Birmingham hip resurfacing arthroplasty were examined using a highly detailed three-dimensional computer model of the hip. Stresses and strains in the proximal femur were compared for the natural femur and for the femur resurfaced with the Birmingham hip resurfacing. A comparison of cemented versus uncemented fixation showed no advantage of either with regard to bone loading. When the Birmingham hip resurfacing femoral component was fixed to bone, proximal femoral stresses and strains were non-physiological. Bone resorption was predicted in the inferomedial and superolateral bone within the Birmingham hip resurfacing shell. Resorption was limited to the superolateral region when the stem was not fixed. The increased bone strain observed adjacent to the distal stem should stimulate an increase in bone density at that location. The remodelling of bone seen during revision of failed Birmingham hip resurfacing implants appears to be consistent with the predictions of our finite element analysis.
Congenital dislocation of the hip
Authors: Vallamshetla V. R. P. , Mughal E. , O’Hara J. N.
Published: July 2006

Difficulties posed in managing developmental dysplasia of the hip diagnosed late include a high-placed femoral head, contracted soft tissues and a dysplastic acetabulum. A combination of open reduction with femoral shortening of untreated congenital dislocations is a well-established practice. Femoral shortening prevents excessive pressure on the located femoral head which can cause avascular necrosis. Instability due to a coexisting dysplastic shallow acetabulum is common, and so a pelvic osteotomy is performed to achieve a stable and concentric hip reduction. We retrospectively reviewed 15 patients (18 hips) presenting with developmental dysplasia of the hip aged four years and above who were treated by a one-stage combined procedure performed by the senior author. The mean age at operation was five years and nine months (4 years to 11 years). The mean follow-up was six years ten months (2 years and 8 months to 8 years and 8 months). All patients were followed up clinically and radiologically in accordance with McKay’s criteria and the modified Severin classification. According to the McKay criteria, 12 hips were rated excellent and six were good. All but one had a full range of movement. Eight had a limb-length discrepancy of about 1 cm. All were Trendelenburg negative. The modified Severin classification demonstrated four hips of grade IA, six of grade IB, and eight of grade II. One patient had avascular necrosis and one an early subluxation requiring revision.

One-stage correction of congenital dislocation of the hip in an older child is a safe and effective treatment with good results in the short to medium term.
Fracture of the atlas through a synchondrosis of the anterior arch complicated by atlantoaxial rotatory fixation in a four-year-old child
Authors: Hagino T. , Ochiai S. , Tonotsuka H. , Tokai M. , Senga S. , Hamada Y.
Published: July 2006

Fracture of the atlas is rare in children. We report a case of fracture of the atlas through a synchondrosis of the anterior arch complicated by atlantoaxial rotatory fixation in a four-year-old girl.
The long-term results of press-fit cemented stems in total knee prostheses
Authors: Langlais F. , Belot N. , Ropars M. , Lambotte J. C. , Thomazeau H.
Published: July 2006

We evaluated the long-term fixation of 64 press-fit cemented stems of constrained total knee prostheses in 32 young patients with primary malignant bone tumours. Initial stable fixation, especially in rotation, was achieved by precise fit of the stem into the reamed endosteum, before cementation. Complementary fixation, especially in migration and rotation, was obtained by pressurised antibiotic-loaded cement. The mean age at operation was 33 years (13 to 61). No patient was lost to follow-up; 13 patients died and the 19 survivors were examined at a mean follow-up of 12.5 years (4 to 21). Standard revision press-fit cemented stems were used on the side of the joint which was not involved with tumour (26 tibial and six femoral), on this side there was no loosening or osteolysis and stem survival was 100%. On the reconstruction side, custom-made press-fit stems were used and the survival rate, with any cause for revision as an end point, was 88%, but 97% for loosening or osteolysis. This longevity is similar to that achieved at 20 years with the Charnley-Kerboull primary total hip replacement with press-fit cemented femoral components.

We recommend this type of fixation when extensive reconstruction of the knee is required. It may also be suitable for older patients requiring revision of a total knee replacement or in difficult situations such as severe deformity and complex articular fractures.