bluuebunny/crossref_metadata_2025 huggingface dataset:
Report—The Nexus: Where Science Meets Society
Authors: Rogers Carol L.
Published: August 2005

Nearly ten thousand scientists, engineers, policymakers, journalists, and others interested in science convened in Washington, D.C., February17to 21,2005, for the annual meeting of the American Association for the Advancement of Science. The meeting, which focused on the intersection of science and society, included plenary lectures, symposia, an exhibition, and family science days, among other activities.
Uphill Transport of Saccharides across an Anion-Exchange Membrane
Authors: Shigemasa Yoshihiro , Terada Naofumi , Mori Takatoshi , Morimoto Minoru , Sashiwa Hitoshi , Saimoto Hiroyuki
Published: August 2005

Unmodified carbohydrates were transported across an anion-exchange membrane from a neutral solution cell (Part O) to a basic solution cell (Part A) against their concentration gradients. The amount of each sugar transported across the membrane tended to decrease along with an increase in the pKa value of the sugar. The transportation was dependent on the presence of a hydroxide-ion concentration gradient. These results suggest the uphill transport of sugars based on a coupled counter-transport of hydroxide ion through the anion-exchange membrane. A comparison of the transportation of monosaccharides with that of disaccharides showed that the steric bulkiness of the sugar molecules affected the amount of each sugar transported. Among the water-soluble organic solvents which have a membrane swelling effect, acetonitrile, having the larger dielectric constant, was found to be a highly effective cosolvent to facilitate uphill transport. When aqueous KOH (10 mM) containing d-fructose (2 mM) was added to Part A and a solution of d-fructose (2 mM) in a 3 : 7 mixture of water and acetonitrile was added to Part O, the dialysis at 20 °C for 3 h changed the ratio of the amount of d-fructose in Part A to the amount of d-fructose in Part O from 50 : 50 to 72 : 28.
Synthesis and Crystal Structure of a Novel Hexanuclear Zr(IV) Complex with Hydroxo and Carboxylato Bridging
Authors: Reza Mohammad Yeamin , Matsushima Hideaki , Koikawa Masayuki , Nakashima Michio , Tokii Tadashi
Published: August 2005

A novel hexanuclear eight-coordinate complex, [Zr6(OH)8(OCH3)4(Ph2CHCOO)12]·2CH3CN (1), has been prepared and characterized on the basis of elemental analysis, infrared-spectroscopy measurements, and X-ray crystallography. The crystallographic data for complex 1 are : monoclinic, P21/n, a = 18.09(1), b=21.73(2), c = 20.349(8) Å, β = 96.26(4)°, V = 7952(8) Å3, Z = 2, R = 0.055 and Rw = 0.058 for 5133 observed reflections [I > 3σ(I)]. Complex 1 resides on a crystallographic inversion center, thus making only three of the six zirconium unique. The six zirconium ions are arranged in apices of an octahedron. Two axial Zr(IV) metal ions (Zr1, Zr1*) are joined with four equatorial Zr(IV) metal ions (Zr2, Zr2*, Zr3, Zr3*) by eight syn–syn bridging carboxylate groups, and both axial Zr(IV) ions have four triangle μ3-OH bridges through equatorial Zr(IV) metal ions. On the other hand, each equatorial Zr(IV) metal ion is connected with axial Zr(IV) metal ions by two bridging carboxylates and four triangle μ3-OH bridges. Besides these, each equatorial Zr(IV) metal ion is coordinated by one monodentate carboxylate and one methoxy group.
Novel S-Bridged CoIIIPdII Polynuclear Complexes Derived from [NiII{CoIII(aet)2(en)}2]Cl4 (aet = 2-Aminoethanethiolate). Crystal Structures of [Pd{Co(aet)2(en)}2]Cl4 and [PdCl2{Co(aet)2(en)}]Cl
Authors: Konno Takumi , Machida Takayuki , Okamoto Ken-ichi
Published: August 2005

The reaction of an S-bridged CoIIINiIICoIII trinuclear complex, [Ni{Co(aet)2(en)}2]Cl4 (1), with Na2[PdCl4] in a ratio of 1 : 1 gave an S-bridged CoIIIPdIICoIII trinuclear complex, [Pd{Co(aet)2(en)}2]Cl4 (2), while the corresponding 1 : 2 reaction produced an S-bridged CoIIIPdII dinuclear complex, [PdCl2{Co(aet)2(en)}]Cl (3). The crystal structures of 2 and 3 were determined by X-ray crystallography: 2·6H2O crystallizes in the monoclinic space group C2/c with a = 14.951(2), b = 19.753(2), c = 12.926(2) Å, β = 113.33(1) °, V = 3505.4(9) Å3, Z = 4, and R = 0.034. 3·2H2O crystallizes in the monoclinic space group P21/n with a = 14.282(5), b = 8.497(2), c = 16.139(6) Å, β = 115.13(1) °, V = 1773(1) Å3, Z = 4, and R = 0.026. In 2 the PdII atom is coordinated by four S atoms from two C2-cis(S)-[Co(aet)2(en)]+ units, while the PdII atom in 3 is coordinated by two Cl atoms besides two S atoms from one octahedral C2-cis(S)-[Co(aet)2(en)]+ unit. 2 was readily converted to 3 by the reaction with Na2[PdCl4], while the conversion of 3 to 2 was achieved by reacting 3 with 1. 2 and 3 were optically resolved and their electronic absorption and CD spectral behavior is also reported.
Optimization of a Regression Model for a Quantitative Structure. Mutagenicity Relationship of Some Natural Amino Acids
Authors: Kuanar Minati , Mishra Bijay K
Published: August 2005

Multivariate statistical tools, such as principal-component analysis and multiple-regression analysis, were used for a large number of structural and empirical parameters of some eleven natural amino acids for predicting mutagenicity. An optimized regression model was derived from some selective principal components and solubility data. Plots related to the principal components resulted in the ordination of amino acids as well as the structural and empirical parameters.
Rearrangement Approaches to Cyclic Skeletons. XIII. Total Synthesis of Triquinane Sesquiterpenes, (±)-Modhephene, and (±)-Isocomene, on the Basis of Formal Substitution at Both Bridgeheads of a Bicyclo[2.2.2]oct-5-en-2-one
Authors: Uyehara Tadao , Murayama Tomohiro , Sakai Katsunori , Onda Kayoko , Ueno Masako , Sato Toshio
Published: August 2005

A reaction of 1,4-dimethoxybicyclo[2.2.2]oct-5-en-2-one and R1MgX, followed by treatment with p-toluenesulfonic acid in benzene, gave the 5-methoxybicyclo[3.2.1]oct-6-en-2-one having a substituent (R1) at the C-1 bridgehead. This ketone was converted into the 5-methoxybicyclo[3.2.1]oct-3-en-2-one. By treatment with Li[CuR2], a second bridgehead substituent (R) was introduced at the C-4 position of the conjugated ketone. The product was converted into the corresponding α,β-unsaturated ketone, and then treated with R2Li or DIBAL-H (R2 = H). Acid treatment of the resulting allyl alcohols gave the bicyclo[2.2.2]oct-5-en-2-one having substituents R, R1, and R2 at the C-1, 4, and 5 positions, respectively. This procedure was successfully applied to a formal total synthesis of (±)-modhephene, a propellane-type triquinane sesquiterpene, and that of (±)-isocomene, an angular triquinane sesquiterpene, on the basis of an oxa-di-π methane rearrangement of the bicyclo[2.2.2]oct-5-en-2-ones.
Transition Metal-Catalyzed Intramolecular Cyclization of 1,5- and 1,6-Dienes via Direct Cleavage and Addition of the Carbon–Hydrogen Bond
Authors: Fujii Naoaki , Kakiuchi Fumitoshi , Yamada Airi , Chatani Naoto , Murai Shinji
Published: August 2005

Ruthenium- and rhodium-catalyzed intramolecular C–H/olefin coupling reactions of 1-(2-pyridyl)-, 1-(2-imidazolyl)-, and 1-(2-oxazolyl)-1,5-dienes proceeded in a regiospecific manner to give 5-membered ring products. Their 1,6-diene analogues are also applicable to the cyclization reaction to give the corresponding 5- and 6-membered carbocycles. For the cyclization of the pyridine derivatives, [RhCl(PPh3)3] showed the highest catalytic activity with respect to efficiency and selectivity. When the imidazole derivatives were employed to the cyclization reaction, the combination of the rhodium(I) complex and the relatively sterically bulky phosphine (e.g., PCy3 and PPFOMe) was a quite effective catalyst system. In the case of the oxazoles, the ruthenium complex, [Ru(H)2(CO)(PPh3)3], showed the highest activity among the catalysts examined. These catalytic reactions usually proceed at 120 °C. The [RhCl(PPh3)3]-catalyzed cyclization reaction of 2-[(1E)-4,4-dimethyl-1,5-hexadienyl]pyridine smoothly proceeded even at room temperature to give the corresponding cyclized product in 93% yield after 24 h. A hybrid catalyst system containing the rhodium(I) and both PPh3 and P(o-tolyl)3 had a slightly better catalytic activity compared with that of [RhCl(PPh3)3]. The intramolecular cyclization can be also applied to the C–H/CO/olefin coupling reactions. These carbonylation reactions gave the 5-membered ring ketones exclusively. The intramolecular C–H/olefin coupling reactions provide a new entry for constructing carbocyclic compounds from 1,n-dienes.
Electronic Transitions of Ternary Copper(II) Naphthalenediolate Complexes
Authors: Yamada Yasunori , Hasegawa Miki , Kobayashi Michio , Fukuda Yutaka , Hoshi Toshihiko
Published: August 2005

The electronic structure and nature of the electronic transitions of copper(II) naphthalenediolate complexes, (2,2′-bipyridine) (2,3-naphthalenediolato) copper(II) ([Cu(ndo)(bpy)]) and (2,3-naphthalenediolato) (1,10-phenanthroline) copper(II) ([Cu(ndo)(phen)]), have been studied from the viewpoints of the polarization spectra and MO theory. The 339.0 and 296 nm bands of [Cu(ndo)(phen)] have been assigned to localized transitions of the naphthalenediolate (ndo) skeleton, and the 308, 275, and 269 nm bands on the phenanthroline (phen) skeleton. It has been clarified experimentally that the 400 nm band can be assigned to the CT transition between ndo and Cu(II). The total state wavefunctions show that the 293 and 282 nm bands are due to the intramolecular interligand CT (LL′CT) transitions from ndo to phen, thus indicating that the two π-electronic systems, separated by the central metal ion, can directly interact. The complex [Cu(ndo)(bpy)] shows the electronic transitions at 339.0, 256.0, 245, 238, and 210 nm localized on ndo, and at 315, 295, and 264 nm localized on the bipyridine (bpy) moiety. The 400 nm band of [Cu(ndo)(bpy)] is due to the intramolecular CT transition between ndo and Cu(II). In the case of [Cu(ndo)(bpy)], the LL′CT transition is not observed.
Infrared Spectroscopic Observation of Intermediate Species on Ni and Fe Electrodes in the Electrochemical Reduction of CO2 and CO to Hydrocarbons
Authors: Koga Osamu , Matsuo Tadanori , Yamazaki Hiroki , Hori Yoshio
Published: August 2005

Adsorbed species on Ni and Fe electrodes were investigated by in-situ infrared spectroscopy in the electrochemical reduction of CO2 or CO. Two types of adsorbed CO on the Ni electrode and one type on the Fe electrode were detected in a CO atmosphere. The two types, assigned to linear and bridged CO molecules, were also formed on the Ni electrode in CO2 reduction. The negative polarization decreased the coverage of the adsorbed CO on Ni. The decay rate constants were evaluated from the spectroscopic data; the rate constant for the linear type was three times higher than that for the bridge one. Both constants agreed well with those determined from the formation rate of hydrocarbons in CO reduction, confirming that both adsorbed CO molecules were intermediate species to hydrocarbons. The high electrocatalytic activity of Cu in hydrocarbon formation from CO2 and CO was rationalized in terms of the adsorption strength of CO on metals by comparing the activity of Ni, Fe, and Cu electrodes with the infrared bands of adsorbed CO on these electrodes. The weaker adsorption of CO on Cu led to higher activity.
Solid-State Photodimerization of Methyl (RS)-1-Phenyl-2-piperidinoethyl (RS)-1,4-Dihydro-2,6-dimethyl-4-(2-thiazolyl)pyridine-3,5-dicarboxylate Hydrochloride Controlled by the Buffer Zone
Authors: Marubayashi Nobuhiro , Ogawa Takayuki , Hirayama Noriaki
Published: August 2005

The solid-state photodimerization of three polymorphic crystal forms (forms I, II, and III) of a bulky olefin, methyl (RS)-1-phenyl-2-piperidinoethyl (RS)-1,4-dihydro-2,6-dimethyl-4-(2-thiazolyl)pyridine-3,5-dicarboxylate hydrochloride, was studied. Forms I and II are anhydrous crystals and form III is an isomorphous hydrate of form II. X-Ray analyses of these forms showed that forms II and III have the same geometrical characteristics suggesting high susceptibility to photodimerization according to the well-known topochemical rule. Although UV irradiation of from II affords a photodimer, 4a,8a-dimethoxycarbonyl-2,4b,6,8b-tetramethyl-3-[(RS)-1-phenyl-2-piperidinoethoxycarbonyl]-7-[(SR)-1-phenyl-2-piperidinoethoxycarbonyl]-(4RS,8SR)-4,8-di(2-thiazolyl)-1,4,4a,4b,5,8,8a,8b-octahydro-cis-transoid-4a,4b-cis-cyclobuta[1,2-b : 3,4-b′]dipyridine, in high yield, the photolysis of form III proceeds much more slowly than that of form II. A detailed inspection of the crystal structures revealed that there is a space to afford the mobility of molecules for dimerization in form II, whereas the space is occupied by the incorporated water molecule in form III. We have previously proposed that a buffer zone, which is a space in the crystal structure, controls the photodimerization of bulky olefins. The present study demonstrates that the buffer zone is an essential controlling factor for the solid-state photodimerization of bulky olefins.
Electronic Structure and UV Absorption Spectra of 2-Pyridylacetylenes: An Intramolecular Orbital Interaction between the n Orbital on the Nitrogen Atom of the Pyridine Ring and the In-plane π Orbital of the Ethynylene Group
Authors: Okubo Jun , Shinozaki Hiraku , Koitabashi Toshiyuki , Yomura Ryo
Published: August 2005

The UV absorption spectra of some pyridylacetylenes were measured in various media at room temperature and 77 K, and the origin of the electronic absorption bands of these compounds was clarified compared with the results of MO calculations. For instance, it has been found that the 304.6, 271.7, 221, and 216 nm bands of 1-(2-pyridyl)-2-phenylethyne in cyclohexane can be assigned to the calculated S1 ← S0, S5 ← S0, S9 ← S0, and S10 ← S0 transitions, respectively, in which the observed 271.7 nm band (S5 ← S0) is ascribed as a new type transition from the n orbital on the aza-nitrogen atom of the pyridine ring to the in-plane π* orbital on the sp-carbon atoms of the ethynylene group. Furthermore, it is revealed that the observed 259.6 nm band of 1,2-di(2-pyridyl)ethyne (D2PE) can also be assigned to a new type of transition caused by weak interactions between the n orbitals and the in-plane π orbital of the ethynylene group. This result indicates that two n orbitals of the terminal pyridine rings of D2PE may interact with each other via the central in-plane π orbital.
Temperature Effect on the Depolarization Degree of the Raman Active Totally Symmetric Vibrations of Some Benzene Derivatives Belonging to Point Groups D6h and D3h
Authors: Yumura Tetsuji , Koga Makoto , Hoshikawa Hironori , Nibu Yoshinori , Shimada Ryoichi , Shimada Hiroko
Published: August 2005

The temperature effect on the depolarization degree of the Raman bands of the totally symmetric vibrations of some benzene derivatives belonging to point groups D6h and D3h was studied. In these molecules a direct field due to incident light gives rise to an intrinsic depolarization, and an indirect field causes by dipoles induced in the surrounding molecules by the incident light gives rise to depolarization due to intermolecular interactions. It was observed that although the depolarization degree increases with increasing temperature for all vibrational modes, the relationship between the temperature and depolarization degree is different, depending on the vibrational modes as well as the substituents. These observations are qualitatively explained by a change in the intermolecular interaction due to thermal fluctuations of the intermolecular distance caused by molecular vibrations.
Effect of Copper(I) on Hydrogenase Activity from Desulfovibrio vulgaris (Miyazaki)
Authors: Kamachi Toshiaki , Okura Ichiro
Published: August 2005

Effect of copper ion on the activity of the hydrogenase from Desulfovibrio vulgaris (Miyazaki) was studied. When the hydrogenase was incubated with Cu(II) ion, the hydrogenase activity did not change. The hydrogenase activity was inhibited when the hydrogenase was incubated with copper ion in the presence of sodium ascorbate, suggesting the effect of Cu(I) ion. ESR studies indicate that the signal intensity attributed to [3Fe–4S] cluster decreased with decreasing the activity. Copper contents of hydrogenase increased, but the contents of iron and nickel did not change. Results obtained demonstrate that incorporated Cu(I) affects the hydrogenase a activity by the perturbation of [3Fe–4S] cluster.
A Thermolytic Azulene Synthesis from Dimethyl 4-Morpholino-3,3a,8,8a-tetrahydroazulene-5,6-dicarboxylates and Its 1-Substituted Derivatives
Authors: Kuroda Shigeyasu , Hirooka Syuzi , Oda Mitsunori , Iwaki Hiroyuki , Teranishi Syuki , Matsushita Noriko , Hongou Tamotsu , Ikeda Mariko , Hayashi Syuichi , Miyatake Ryuta , Izawa Mayumi , Yamada (the late) Masaki , Shimao Ichiro
Published: August 2005

The thermolysis of 1-substituted 4-morpholino-3,3a,8,8a-tetrahydroazulene-5,6-dicarboxylates derivatives (7a—c) under catalytic dehydrogenation conditions was studied. The reaction substrates were prepared by a several-step sequence involving the [2+2] cycloaddition of bicyclc morpholino enamines with dimethyl acetylenedicarboxylate, and a subsequent electrocyclic opening of the cyclobutene ring as a key skeletal construction, starting from bicyclo[3.3.0]octane-2,6-dione mono(ethylene acetal). Refluxing of a diphenyl ether solution of dimethyl 4-morpholino-3,3a,8,8a-tetrahydroazulene-5,6-dicarboxylate (7a) containing a catalytic amount of Pd–C gave a 10% yield of dimethyl azulene-5,6-dicarboxylate (8a), accompanied by a 10% yield of dimethyl azulene-4,6-dicarboxylate (9a), trace amounts of dimethyl azulene-5,7-dicarboxylate (10a), methyl azulene-5-carboxylate (12a), and methyl azulene-6-carboxylate (13a). Under the same thermolytic conditions, a 1-phenyl-substituted compound 7b gave corresponding similar types of phenyl-substituted azulenes (8b, 9b, 10b, 11b, and 14b), and a 1-cyano-substituted compound 7c gave a mixture of corresponding similar types of cyano-substituted azulenes (8c, 9c, 10c, and 11c). This sequence provides a new method for synthesizing substituted azulenes suffering from migration and removal of one ester group. Also the thermolysis of a similar system of dimethyl 3-(1-pyrrolidinyl)-2,7-cycloheptadiene-1,2-dicarboxylate (15), even in the absence of a catalyst, gave cycloheptatriene derivatives of dimethyl 1,3,5-cycloheptatriene-dicarboxylate (16, 17, 18, and 19), bearing no morpholine molecule.
Palladium-Catalyzed Arylation of Azole Compounds with Aryl Halides in the Presence of Alkali Metal Carbonates and the Use of Copper Iodide in the Reaction
Authors: Pivsa-Art Sommai , Satoh Tetsuya , Kawamura Yoshiki , Miura Masahiro , Nomura Masakatsu
Published: August 2005

The reactions of iodobenzene with azole compounds, 1,2-disubstituted imidazoles and 2-substituted oxazoles and thiazoles, were examined in the presence of catalytic amounts of Pd(OAc)2 and PPh3 in DMF using alkali metal carbonates as bases. It was found that the coupling products, 5-arylazoles, could be selectively produced in good yields by using Cs2CO3. In the case that their 2-position is unsubstituted, the site could also be arylated. In reactions using bromobenzene in place of iodobenzene, K2CO3 was also as effective as Cs2CO3. The addition of a stoichiometric amount of CuI appeared to specifically promote the reactions of thiazoles as well as those of thiophene derivatives. The reactions of 2-unsubstituted azole compounds with aryl iodides could be mediated by CuI to some extent without using the palladium species to give 2-arylazoles.
Preparations of Furans from α-Bromo Ketones and Enol Ethers Catalyzed by a Rhenium(I) Nitrogen Complex
Authors: Koga Yuji , Kusama Hiroyuki , Narasaka Koichi
Published: August 2005

By the catalytic use of a rhenium(I) nitrogen complex, [ReCl(N2)(PMe2Ph)4], α-keto radicals are generated from α-bromo ketones and react with vinyl ethers and silyl enol ethers intermolecularly. Various substituted furans, including tetrasubstituted furans such as furoguaiacin, are prepared by this method.
Norbornadiene-Fused Heterocycles: Synthesis of 5,8-Dihydro-5,8-methanophthalazines and Regioselective Ring Cleavage and Skeletal Rearrangement of 6,7-Epoxy-5,6,7,8-tetrahydro-5,8-methanophthalazine 2-Oxides in Trifluoroacetic Acid
Authors: Kobayashi Tomoshige , Sugawara Hideki , Nikaeen Behrooz
Published: August 2005

5,8-Dihydro-5,8-methanophthalazine, prepared by the reaction of bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarbaldehyde with hydrazine, reacted with MCPBA to give an N-oxide. Further oxidation with MCPBA afforded the corresponding exo-6,7-epoxy derivative. Treatments of the epoxide and its diphenyl-substituted derivative with trifluoroacetic acid gave 6,9-bis(trifluoroacetoxy) derivatives by a regioselective ring-opening of the oxirane, accompanied by Wagner–Meerwein rearrangement. The bis(trifluoroacetoxy) derivatives were converted to the corresponding diols for elucidation of their regio- and stereochemistry.
Electrochemical Lithium Intercalation within Carbonaceous Materials: Intercalation Processes, Surface Film Formation, and Lithium Diffusion
Authors: Ogumi Zempachi , Inaba Minoru
Published: August 2005

Electrochemical lithium intercalation within carbonaceous materials has attracted much attention for use to produce anodes in rechargeable lithium batteries. Although small-size rechargeable lithium cells using carbon anodes have been already commercialized, there still remain a lot of problems to be solved. Furthermore, recent global environmental issues require carbon anodes with high energy densities for use in electric energy storage and electric vehicles in the near future. This review article covers recent topics of the lithium intercalation, focusing on three fundamental aspects: intercalation processes, surface film formation, and lithium diffusion within carbons.
Some Theoretical Considerations Concerning Ion Hydration in the Case of Ion Transfer between Water and 1,2-Dichloroethane
Authors: Sánchez C , Leiva E , Dassie S A , Baruzzi A M
Published: August 2005

Some aspects of direct ion transfer across water/1,2-dichloroethane have been analyzed using a very simple model based on thermodynamic considerations. It was concluded that ion solvation by water molecules may occur in some particular cases in the organic phase, delivering an important contribution to the Gibbs free energy of ion transfer between the aqueous and the organic phase. In general terms, this particular type of transfer should be favored in the case of highly charged small ions at interfaces with a relatively low surface tension and a large difference between the reciprocal of the corresponding dielectric constants.
Catalytic Reforming of Methane with Carbon Dioxide on LaBO3 (B = Co, Ni, Fe, Cr) Catalysts
Authors: Wu Yunying , Kawaguchi Osamu , Matsuda Tsuneo
Published: August 2005

The reforming reactions of CH4 with CO2 diluted with He on perovskite structural oxides, LaBO3 (B = Co, Ni, Fe, Cr), were examined. The reaction activity at 1073 K followed the order LaCoO3 > LaNiO3 > LaFeO3 > LaCrO3, and the highest selectivities to CO and H2 were obtained on a LaCoO3 catalyst. The reaction on the LaCoO3 catalyst under the reaction condition of CH4/CO2 = 1 showed a H2/CO ratio of 1; the ratio was less than 1 on other catalysts. In the initial stage of the reactions of CH4 + CO2 on LaCoO3 and LaNiO3 catalysts, an induction period accompanying the reduction of the catalysts was observed. During the reforming reaction, both the LaCoO3 and LaNiO3 catalysts were decomposed by reduction to Co to Ni metal and La2O3. No induction period, however, was observed in the reaction on the LaFeO3 and LaCrO3 catalysts, which were stable during the reaction. The high activity of the decomposed LaCoO3 catalyst is ascribed here —as a result of EPMA, SEM analysis and of comparison with the reaction behaviors of Co catalysts supported on La2O3 — to the high concentration of metallic cobalt uniformly dispersed as fine particles on the catalyst surface. The reaction mechanism on the cobalt metal was inferred from the results of the reaction of CH4 or CO2 alone on the decomposed LaCoO3 catalyst.
Kinetics and Mechanisms of Hydrogen Peroxide Disproportionation Catalyzed by Mononuclear Schiff Base Manganese(III) Complexes: Effects of Chelate and Hydroxide Ion on Hydrogen Peroxide Disproportionation in N,N-Dimethylformamide
Authors: Uehara Minori , Urade Mika , Abe Yuriko
Published: August 2005

The preparation of [Mn(saltnOCOPh)Cl]·DMF (H2saltnOCOPh: N,N′-(2-benzoyloxypropane-1,3-diyl)bis(salicylideneamine)) and kinetics and mechanisms of H2O2 disproportionation catalyzed by mononuclear Schiff base manganese(III) complexes, such as [Mn(salen)Cl] (H2salen: N,N′-ethylenebis(salicylideneamine)), [Mn(saltn)Cl] (H2saltn: N,N′-propane-1,3-diylbis(salicylideneamine)), [Mn(saltnOH)Cl] (H2saltnOH: N,N′-(2-hydroxypropane-1,3-diyl)bis(salicylideneamine)), and [Mn(saltnOCOPh)Cl] in N,N-dimethylformamide (DMF), have been investigated. The disproportionation of H2O2 to O2 and H2O proceeds coupled with the redox cycle between the Mn(III) complex and the Mn(IV) intermediate: the first step is the fast equilibrium (Km) of the Mn(III) complex and the Mn(IV) intermediate formed by the reaction of the Mn(III) complex with H2O2, followed by a slow reaction (k1) of the Mn(IV) intermediate with H2O2 to produce O2 and H2O recovering the original Mn(III) complex. The Km values decrease in the following order: [Mn(salen)Cl] (728 mol−1 dm3) >> [Mn(saltnOH)Cl] (28.0 mol−1 dm3) > [Mn(saltn)Cl] (6.28 mol−1 dm3) > [Mn(saltnOCOPh)Cl] (1.83 mol−1 dm3), reflecting an increased distortion along the axis containing the coordination of H2O2 to the Mn(III) complex. On the other hand, the rate constants (k1) fall into the following sequences: [Mn(saltnOH)Cl] (4.29 × 105 mol−2 dm6 s−1) > [Mn(salen)Cl] (1.67 × 105 mol−2 dm6 s−1) > [Mn(saltnOCOPh)Cl] (3.34 × 104mol−2 dm6 s−1) > [Mn(salen)Cl] (6.15 × 103 mol−2 dm6 s−1). In spite of the small Km values for saltnOH, saltnOCOPh, and saltn complexes with the 1,3-diamine ligand, compared to that for the salen complex, the large k1 value for the saltnOH complex strongly suggests stabilization of the transition state for the formation of hydrogen-bondings among the Mn(IV) intermediates and H2O2. Futhermore, the effect of the OH− ion on the H2O2 disproportionation catalyzed by [Mn(salen)Cl] has been reported. On account of the formation of [Mn(salen)OH] coordinated by the OH− ion, the appearance of the reaction path involving not only the Mn(III)–Mn(IV) cycle, but also the Mn(II)–Mn(III) cycle, is shown based on the ESR and visible spectral studies. The activity for the Mn(II)–Mn(III) cycle is 20 times larger than that for the Mn(III)–Mn(IV) cycle.
Determination of Ultratrace Gallium in River Water by Electrothermal Atomic Absorption Spectrometry after Preconcentration with Solvent Extraction and Back Extraction
Authors: Kawaguchi Hiroshi , Shimizu Tokuo , Shirakashi Takashi , Shijo Yoshio
Published: August 2005

A method for the determination of gallium at ng dm−3 levels in river water is described. Gallium is extracted into carbon tetrachloride as an ion pair of gallium–5-sulfo-8-quinolinol (H2QS) chelate anion with tetradecyldimethylbenzylammonium chloride (Zephiramine), and subsequently back-extracted into 0.3 cm3 of a nitric acid solution. The high efficiency of extraction and back extraction allows gallium to be concentrated about 5000-fold with a combined single extraction and back extraction. The back-extracted solution, containing 250 μg cm−3 of nickel as a matrix modifier, is suitable for the determination of gallium by electrothermal atomic absorption spectrometry (ETAAS). The detection limit (3σ) for gallium is 0.29 ng dm−3 based on a 1500-fold preconcentration. The concentration of dissolved gallium in river water was found to be 5.3—9.2 ng dm−3 by the proposed method.
Calix[4]arene-Modified Oligosiloxane as a Quasi-Immobilized Neutral Carrier for Silicone-Rubber-Membrane Sodium Ion-Selective Electrodes
Authors: Kimura Keiichi , Tsujimura Yutaka , Yokoyama Masaaki , Maeda Takumi
Published: August 2005

An oligo(dimethylsiloxane) carrying ionophorous calix[4]arene moieties at the side chain was synthesized as a Na+ neutral carrier for highly durable silicone-rubber membranes of ion-selective electrodes by reacting calix[4]arene tetraallyl ester with an oligo(methylsiloxane). This medium-molecular-weight calix[4]arene ionophore alleviated the drawback of chemically-modified calixarene-based silicone-rubber membranes, such as a high membrane impedance and a slow electrode response.
Kinetic Coupling of Formaldehyde Oxidation and Oxide Formation on a Platinum Electrode
Authors: Nakabayashi Seiichiro , Tamura Kazuhisa , Uosaki Kohei
Published: August 2005

The reflectivity of a p-polarized laser beam on a polycrystalline platinum electrode is sensitive to the formation and reduction of the surface oxide. The derivative of this reflectivity is proportional to the current for the oxide formation and reduction. The reflectivity indicates the partial current for the oxide formation and reduction, which is hidden in the total current, including the 4-electron oxidation of formaldehyde. The time course of the reflectivity by a potential-step perturbation shows that formaldehyde makes the rate of the oxide formation and the reduction drastically asymmetric due to dissociative adsorption on the oxide-free platinum-electrode surface.
Synthesis and Properties of 9-(Tropylidenehydrazono)fluorene and Related Compounds
Authors: Minabe Masahiro , Nozawa Toshiya , Kurose Tomoko , Kimura Takao , Tsubota Motohiro
Published: August 2005

9-(Tropylidenehydrazono)fluorene (1) was obtained by a reaction between 9-fluorenone hydrazone and tropylium tetrafluoroborate, accompanied by 9-fluorenone azine, 9-(benzylidenehydrazono)fluorene, and 9,9-ditropylfluorene. The amination of 1 occurred at the 2-position of the tropylidene moiety. The addition of tosyl isocyanate to 1 gave the [8 + 2] cycloadduct at the 2,4,6-cycloheptatrien-1-imine structure.
Design and Synthesis of Peptides Passing through the Blood-Brain Barrier
Authors: Wakamiya Tateaki , Kamata Makoto , Kusumoto Shoichi , Kobayashi Hiroyuki , Sai Yoshimichi , Tamai Ikumi , Tsuji Akira
Published: August 2005

The blood-brain barrier (BBB) is a highly selective membranous barrier regulating the transport of substances in blood into the brain parenchyma. At present, delivery of biologically active peptides or peptide drugs into the brain is quite an important subject from the standpoint of chemotherapy for brain diseases. H–MeTyr–Arg–MeArg–d-Leu–NH(CH2)8NH2 termed 001-C8 was first synthesized to elucidate the structural specificity of peptides for passing through the BBB. The Nα-methylamino acid and d-amino acid residues were appropriately situated in this peptide to protect against the digestion by peptidase. Furthermore, a number of basic peptides were prepared as 001-C8 analogs for studying the relationship between structure and BBB permeability of peptides.
The Salt-Induced Sphere–Rod Transition of Micelles of 1-Tetradecylpyridinium Bromide in Aqueous NaBr Solutions
Authors: Fujio Katsuhiko
Published: August 2005

Static light scattering from aqueous NaBr solutions of 1-tetradecylpyridinium bromide (TPB) has been measured over the range of NaBr concentrations from 0 to 0.50 mol dm−3 at 25 °C, and the micelle molecular weight has been estimated. For 0—0.20 mol dm−3 NaBr, the reduced intensity of scattered light does not show any angular dependence, and the molecular weight of the spherical micelle of TPB slightly increases from 27.6 × 103 to 41.4 × 103 with increasing NaBr concentration. Beyond 0.20 mol dm−3 NaBr, the angular dissymmetry of the reduced scattering intensity and a steep increase in the micelle molecular weight from 41.4 × 103 to 177.8 × 103 are observed. Therefore, TPB has been considered to form rodlike micelles. The linear double logarithmic relationship between molecular weight and ionic strength holds for spherical and rodlike micelles, respectively. From the intersection of these two lines, the threshold NaBr concentration for the sphere-rod trainsition of TPB micelle is estimated to be 0.19 mol dm−3, where the micelle has a molecular weight of 41.3 × 103.
The Micellar Parameters of α,ω-Alkanediammonium Bis(decyl sulfate) Solutions and Their Mixtures
Authors: Satake Iwao , Kamikado Junichiro , Yasuda Youji , Maeda Tamaki , Hayakawa Katumitu
Published: August 2005

Conductometric and fluorescence probe investigations were carried in order to elucidate the micellar parameters of α,ω-alkanediammonium bis(decyl sulfate) with carbon-chain lengths (n) from 4 to 8 and their mixtures. In single surfactant systems, an increase in n was accompanied by a regular decrease in the critical micelle concentration (cmc) and a rapid increase in the micelle aggregation number (m), while the binding degree of the counter ion head group remained virtually constant at 0.90. The transfer free energy per methylene group of the counter ion from aqueous to micellar environments varied with increasing n from −0.35 kT to −0.68 kT. This fact suggests that the hydrocarbon chain of the counter ion, even with n = 4, can participate in the weak hydrophobic interaction with the micellar interior. In mixed solutions of n = 4 and 6, and n = 4 and 8, the cmc vs. y (mole fraction of n = 4) curves can be well interpreted in terms of the ideal mixing model. In both systems, the value of m gradually increases with increasing y. The fluorescence probe experiments indicate that the local environment around the solubilized pyrene in the mixed micelle resembles one another, regardless of y.
Surface Species Produced by the Reaction between Methane and Oxygen Radical Anion O·− on MgO at 298 K
Authors: Goto Akio , Aika Ken-ichi
Published: August 2005

The reaction between gaseous CH4 and surface O·− on MgO was studied at 298 K. The surface O·− was formed through a reaction of N2O with electrons trapped on MgO and examined with EPR. One mole of surface O·− determined by EPR was found to react with one mole of CH4 determined by GC. The resultant surface species were observed by an FT-IR and were identified to be methoxide and weakly absorbed methanol. The adsorbed methanol was produced by the reaction of methyl radicals (the initial product) with the surface hydroxy groups. Both products (methoxide and methanol) are found to be decomposed to CO and H2 at the elevated temperature such as 773 K.
Central Dogma for a Molecular Design Based on DNA: DNB (Databasing/Designable Nanobio) → ENB (Engineering Nanobio) → FNB (Functional Nanobio)
Authors: Nakano Shu-ichi , Sugimoto Naoki
Published: August 2005

Nanobiomaterials have become of broader interest over the past few years. In this review, we demonstrate functional biomolecules that we have constructed based on the biophysical data on nucleotides. We propose three concepts for the development of new nanobiomaterials; DNB (Databasing or Designable Nanobio) is the process of storing the biomolecular properties, ENB (Engineering Nanobio) is the process of conversion of the biomolecular properties to a molecular design, and FNB (Functional Nanobio) is the process of constructing functional molecules based on DNA technologies. Our approach of DNB → ENB → FNB can be the central dogma for a molecular design.
Synthesis and Characterization of Novel Iridium Complexes with Ligands of 2-Phenylimidazo[1,2-a]pyridine Derivatives and Application to Organic Light-emitting Diode
Authors: Takizawa Shin-ya , Nishida Jun-ichi , Tsuzuki Toshimitsu , Tokito Shizuo , Yamashita Yoshiro
Published: August 2005

Novel iridium complexes with ligands of 2-phenylimidazo[1,2-a]pyridines were prepared, and the emission maxima were found to be unusually dependent on the substituents on the phenyl ring. An OLED using the derivative was fabricated to show white emission.
X-ray Analysis of Bond Elongation in VO(acac)2 at the Excited State
Authors: Hoshino Manabu , Sekine Akiko , Uekusa Hidehiro , Ohashi Yuji
Published: August 2005

X-ray crystal structural analysis of bis(acetylacetonato) oxovanadium(IV), VO(acac)2, complex with photoirradiation at low temperatures clearly indicated the structural distortion caused by the production of the excited molecules with the elongated V=O and V–O bonds in the crystalline lattice.
Family Economic Pressure and Adolescent Suicidal Ideation: Application of the Family Stress Model
Authors: Yoder Kevin A. , Hoyt Dan R.
Published: August 2005

This study used a sample of 501 families from the Mississippi Delta region to examine the feasibility of the Family Stress Model for understanding adolescent suicidal ideation. The results indicated that family economic pressure was related to parental depressive symptoms, which, in turn, was related to parental hostile behavior and physical abuse. These parental behaviors were related to adolescent self‐esteem and depressive symptoms, which, in turn, were related to adolescent suicidal ideation. Therefore, family economic pressure and parental depressive symptoms and behaviors were indirectly related to adolescent suicidal ideation. The results indicate the applicability of the Family Stress Model for understanding adolescent suicidal ideation.
Psychopathology Associated with Suicide Attempts Among Rural Adolescents of China
Authors: Liu Xianchen , Tein Jenn‐Yun , Sandler Irwin N. , Zhao Zhongtang
Published: August 2005

This case control study examined the relationship between psychopathological profiles and self‐reported suicide attempts among rural adolescents of China. Cases consisted of 142 adolescents who reported a suicide attempt in the past 6 months in a questionnaire survey (n = 1,365). An equal number of adolescents without reporting a suicide attempt, matched on age, gender, and school class, were selected from the same survey sample as controls. The Youth Self Report (YSR) was used to assess psychopathological profiles for suicide attempters and matched controls. Results indicated that 73% of suicide attempters had at least one behavioral/emotional syndrome, significantly higher than in controls (30%). Logistic regression analyses showed that anxiety/depression (OR = 3.68) and aggression (OR = 5.02) were each significantly associated with increased risk of suicide attempts after controlling for other behavioral problems. These findings demonstrated the independent contribution of anxiety/depression and aggression to suicide attempts in Chinese adolescents.
Indicators Associated with Suicidal Ideation and Suicide Attempts Among 16–35‐Year‐Old Danes: A National Representative Population Study
Authors: Norlev Jeanette , Davidsen Michael , Sundaram Vanita , Kjøller Mette
Published: August 2005

In this study indicators associated with suicidal ideation and suicide attempts in a nationwide representative sample (N = 3,184) of Danes aged 16–35 years were examined. The study was cross‐sectional and had three aims: (1) to draw a profile of persons with and without suicidal tendency established on a combined quartered variable on current suicidal thoughts and/or ever attempted suicide; (2) to explore whether the different suicidal tendencies constitute a severity continuum; and (3) to identify factors of significance for suicidal tendency. Factors included were demographic characteristics, living conditions, social network, external health risks, lifestyle, health‐related quality of life, symptoms, morbidity, and illness behavior. A continuum hypothesis was not supported, as the multiple logistic regression analysis showed no clear gradient in the different forms of suicidal tendency. Cohabitation status (single, p < 0.0001), exposure to violent threats (p < 0.0001), exposure to sexual abuse (p < 0.0001), being a daily smoker (p < 0.0001), doing nothing to stay healthy (p < 0.0004), poor mental health (p < 0.0001), mental symptoms within the past 2 weeks (p = 0.0003), contact with psychologist (p < 0.0001), and absence from work due to illness (p = 0.005) were indicators significantly related to suicidal tendency.
Efficacy of Brief Telephone Psychotherapy with Callers to a Suicide Hotline
Authors: Rhee Wayne K. , Merbaum Michael , Strube Michael J. , Self Susan M.
Published: August 2005

The efficacy of two types of theapy conducted exclusively over the telephone was studied. Clients (N = 55) were recruited from a pool of callers to a suicide hotline and were randomly assigned to a waiting list control (WC) or Solution Focused Brief Therapy (SFBT) or Common Factors Therapy (CFT). It was hypothesized that improvements would be significantly higher in the two therapy conditions compared to the waitlist control and SFBT would be significantly more efficacious than CFT. Results confirmed that improvement was significantly higher in the two treatment conditions compared to the waitlist control, but no difference in improvement was found between SFBT and CFT. The implications of these findings for suicide hotlines are discussed.
Comparison of the Effects of Four Suicide Prevention Programs for Family and Friends of High‐Risk Suicidal Men Who Do Not Seek Help Themselves
Authors: Mishara Brian L. , Houle Janie , Lavoie Brigitte
Published: August 2005

Callers to a suicide prevention center concerned about high risk men were randomly invited to participate in one of four programs: Information Session, Information Session with Telephone Follow‐up, Rapid Referral to mental health and abuse programs, or Telephone Support. Comparison of pre‐test, 2 month post‐test and 6 months follow‐up with 131 participants found that after third party participation, the third party participant reported that the suicidal men had significantly less suicidal ideation, fewer suicide attempts, and less depressive symptoms. Family and friends had less psychological distress, used more positive coping mechanisms, and reported their communication with the suicidal man was more helpful. The Telephone Support was considered the most useful program.
Cross-section measurements for (n, 2n) and (n, p) reactions on platinum isotopes in the neutron energy range of 13.5 to 14.6 MeV
Authors: Luo Junhua , He Guozhu , Liu Zhongjie , Kong Xiangzhong
Published: August 2005

Cross-sections for (n,2n) and (n,p) reactions have been measured on platinum isotopes at the neutron energies of 13.5 to 14.6 MeV using the activation technique. Data are reported for the following reactions: 198Pt(n,2n)197m+gPt, 198Pt(n,2n)197mPt, 192Pt(n,2n) 191Pt, 190Pt(n,2n) 189Pt, 196Pt(n,2n)195mPt+195Pt(n,n
′)195mPt, 194Pt (n,p) 194Ir, 195Pt(n,p)195mIr and 196Pt(n,p)196mIr. The neutron fluences were determined using the monitor reaction 93Nb(n,2n)92mNb or 27Al(n,α) 24Na.
The solubility product of NaUO2PO4·xH2O determined in phosphate and carbonate solutions
Authors: Felmy Andrew R. , Xia Yuanxian , Wang Zheming
Published: August 2005

The solubility product of NaUO2PO4· x H2O was determined in phosphate containing solutions at low pCH+ values in the absence of carbonate and at higher pCH+ values in the presence of carbonate. NaUO2PO4· x H2O exhibited very low solubilities (∼10−7 M in U) over a broad range of hydrogen ion concentrations, NaNO3 concentrations and in the absence of added carbonate. Time Resolved Laser Fluorescence Spectroscopy (TRLFS) analysis of non-carbonate solutions outside of the acidic region revealed the presence of complex mixtures of aqueous U(VI) hydroxyl or phosphate species and uranium phosphate nanoparticles. The presence of the nanoparticles made it impossible to accurately calculate a solubility product for NaUO2PO4· x H2O in the absence of carbonate and at higher pCH+ values. Therefore in order to increase the concentration of U(VI) in solution and thereby verify the solubility product calculated from the most acidic samples, we systematically introduced know concentrations of carbonate, which resulted in the formation of U(VI) carbonate complexes. Development of an accurate aqueous thermodynamic model for the aqueous U(VI) carbonate complexes then allowed calculation of a solubility product for NaUO2PO4· x H2O in the higher pH samples which was in good agreement with the values for the more acidic samples.
Speciation of technetium(IV) chloride under gamma irradiation
Authors: Fattahi M. , Vichot L. , Poineau F. , Houée-Levin C. , Grambow B.
Published: August 2005

Speciation of Tc in aqueous solution is a complex phenomenon because several parameters intervene simultaneously. We show under gamma radiations, it is completely modified. At pH 8.5 TcO2is oxidized to Tc(VII) with a yield of 1.38×10−7mol J−1. At pH 1.5, it was demonstrated that Tc is present as hydroxylated species TcnOy(4n-2y)+(L. Vichot, M. Fattahi, M. Musikas: Radiochim. Acta 91, 263 (2003)). Its oxidation leads also to Tc(VII) with an experimental yield of 1.45×10−7mol J−1. In more acidic solutions, results are consistent with hydrolysis and oxidation of Tc(IV) to Tc(V). As for colloidal solutions of Tc(IV) or TcO2, they give Tc(VII) whereas solutions of TcCl62-at pH 0.5 and 1.5 do not lead directly to Tc(VII). Reduced states of Tc are very sensitive to radiation. Hydrolysis as well as polymerisation of Tc are accelerated. Furthermore the radiolytic processes are pH dependent.
Zirconium decontamination from aqueous media using lateritic minerals
Authors: Khalid Nasir , Daud Muhammad , Ahmad Shujaat
Published: August 2005

The sorption behavior of zirconium on minerals from a lateritic weathering has been carried out to evaluate its potential for the decontamination of zirconium ions from aqueous solutions. Various physico-chemical parameters such as selection of appropriate electrolyte, equilibration time, amount of adsorbent, concentration of adsorbate, effect of diverse ions and temperature were studied in order to simulate the best conditions under which this material can be used as an adsorbent, employing batch method and radiotracer technique. Maximum adsorption was observed at 0.005 mol L−1 acid solutions (HNO3, HCl, H2SO4 and HClO4) using 0.3 g of adsorbent for 1.499×10−4 mol L−1 zirconium concentration in five minutes equilibration time. Studies show that the adsorption of zirconium decreases with the increase in the concentrations of all the acids. The adsorption data follows the Freundlich isotherm over the range of 7.5×10−5 to 3.0×10−3 mol L−1 zirconium concentration. The characteristic Freundlich constants i.e. 1/n = 0.55±0.03 and K=1.36×10−3±7.0×10−5 mol g−1 have been computed for the sorption system. The sorption mean free energy from the Dubinin–Radushkevich isotherm is 11.2±0.4 kJ mol−1 indicating ion-exchange mechanism of chemisorption. The uptake of zirconium increases with the rise in temperature (283-323 K). Thermodynamic quantities i.e. ΔG, ΔS and ΔH have also been calculated for the system. The sorption process was found endothermic.