bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Urea on Hydrophobic Side Chain Interactions in Polypeptides at the Air–Water Interface
Authors: Shibata Akira , Yamashita Shinsuke , Yamashita Takuya 
Published: July 2006

Abstract
The surface activity of urea at the polypeptide monolayer–water interface was investigated by the surface pressure analysis. The expansion of the monolayer is attributed to the penetration of polypeptide monolayer by urea in the subsolution. The hydrophobic side chain interactions in polypeptides are weakened by the action of urea. The surface activity of urea depends on the difference in the chemical composition and the geometrical arrangement of side chains between benzyloxycarbonyl derivatives of basic poly(α-amino acid) and benzyl esters of acidic poly(α-amino acid).
Studies on Lanthanoids–Antimony–Chalcogenides. III. Synthesis and Crystal Data of Nd3SbS6, Ce6Sb8S21, and Ce3Sb3S10
Authors: Gao Jin-zhang , Nakai Izumi , Nagashima Kozo 
Published: July 2006

Abstract
Single crystals of three new sulfides were prepared in evacuated silica tubes heated in the temperature range 890–1200 °C. Nd3SbS6 is a red transparent crystal. Is is tetragonal, space group I41/acd with lattice parameters a=15.54(1) and c=19.52(2) Å. Ce6Sb8S21 and Ce3Sb3S10 are isostructural with La6Sb8S21, and La3Sb3S10, respectively.
Pressure and Temperature Effects on Octahedral-Tetrahedral Equilibria in Pyridine Solutions of Some Cobalt(II) Halides. II
Authors: Kojima Kazuo , Miyashita Takeru , Matsuda Jiro 
Published: July 2006

Abstract
Temperature and pressure effects on the configuration equilibrium of cobalt(II) iodide in pyridine solution have been studied spectrophotometrically. High temperature favors the tetrahedral species but high pressure favors the octahedral species, the heat and volume changes being 65.3 kJ mol−1 and −6 cm3 mol−1, respectively. Comparisons among three kinds of halide are also made.
13C-NMR Spectra of 2-Aryl-2-(1-azolylmethyl)-4-hydroxymethyl-1,3-dioxolanes and Their Ester and Ether Derivatives
Authors: Suezawa Hiroko , Hirota Minoru , Yamamoto Kazuko , Takeuchi Isao , Hamada Yoshiki 
Published: July 2006

Abstract
The 13C-NMR spectra of the title compounds were assigned and the substituent effect was discussed briefly. 13C-NMR of 2-aryl-4-benzoyloxymethyl-2-bromomethyl-1,3-dioxolanes provides the way to discriminate the cis and the trans isomers.
Preparation of New Nitrogen-bridged Heterocycles. 7. Reactions of 3-[Bis(methylthio)methylene]-2(3H)-indolizinones with Some Pyridinium N-Aminides
Authors: Kakehi Akikazu , Ito Suketaka , Wada Bunzo 
Published: July 2006

Abstract
The reactions of 3-[bis(methylthio)methylene]-2(3H)-indolizinones with pyridinium, quinolinium, and isoquinolinium N-aminides gave unstable 1,3-dipolar spiro-adducts with the elimination of a methanethiol, and some of these adducts isomerized thermally to afford the corresponding N-ylide derivatives.
Studies of Bitter Peptides from Casein Hydrolyzate. IV. Relationship between Bitterness and Hydrophobic Amino Acids Moiety in the C-Terminal of BPIa (Arg–Gly–Pro–Pro–Phe–Ile–Val)
Authors: Otagiri Ken , Shigenaga Toshiaki , Kanehisa Hidenori , Okai Hideo 
Published: July 2006

Abstract
In the synthetic studies of bitter peptide BPIa (Arg–Gly–Pro–Pro–Phe–Ile–Val), we synthesized several BPIa analogs to elucidate the participation of the hydrophobic amino acids moiety in the C-terminal in the bitter taste exhibited by BPIa. The syntheses of the peptides were performed by the usual MA (mixed anhydride) and DCC (dicyclohexylcarbodiimide)–HOBt (1-hydroxybenzotriazole) method, and the bitterness of the peptides was organoleptically determined. The BPIa analogs in which more than two hydrophobic amino acids were located in the C-terminal exhibited a bitter taste as strong as that of BPIa.
The Reaction of 1,1-Dimethyl-1-Phenacylhydrazinium Bromide with Aqueous Sodium Hydroxide
Authors: Kano Kunio , Anselme Jean-Pierre 
Published: July 2006

Abstract
The reaction of 1,1-dimethyl-1-phenacylhydrazinium bromide with 1 M aqueous sodium hydroxide give benzoic acid, 3-phenyl-1-methylpyrazole, 5-benzoyl-3-phenyl-1-methylpyrazole, and benzonitrile as the major components; the expected product, 2-benzoyl-5-phenylimidazole was formed in only small amounts. Mechanisms to rationalize the formation of the major products are discussed.
Molecular and Crystal Structures of endo- and exo-N-Methyl-3,7-epoxy-3-methoxy-7-oxo-1,2-benzo-1-cycloheptene-4,5-dicarboximide
Authors: Tamura Hatsue , Ibata Toshikazu , Ogawa Kazuhide 
Published: July 2006

Abstract
The crystal structures of endo- and exo-adducts of 1-methoxy-2-benzopyrylium-4-olate with N-methylmaleimide have been determined by means of X-ray analysis. The colorless crystals of the endo-adduct are orthorhombic, with the space group P212121 and with a=14.432(3), b=11.874(2), c=7.762(1) Å, and Z=4. The colorless crystals of the exo-adduct are monoclinic, with the space group P21/a and with a=13.381(2), b=12.825(1), c=7.4793(4) Å, β=92.13(1)°, and Z=4. The structures were deduced by a direct method and refined by a block-diagonal least-squares technique. The final R values for the endo- and exo-adducts are 0.047 for 1160 observed reflections and 0.067 for 1986 observed reflections respectively. The configurations of the endo- and exo-adducts are coincident with those assigned on the basis of the NMR data. The observed values of the ring-current effect on the N-methyl chemical shift of the endo-adduct and the coupling constants of the vicinal methine protons of both adducts are in good agreement with the ones calculated on the basis of the present X-ray crystal-structure analysis.
ESR Studies of Paramagnetic Species Trapped in Single Crystals of Chloro(5,10,15,20-tetraphenylporphyrinato)cobalt(III)
Authors: Kohno Masahiro , Ohya-Nishiguchi Hiroaki , Yamamoto Kiyoko , Sakurai Tosio 
Published: July 2006

Abstract
The ESR spectra of three paramagnetic species trapped in single crystals of chloro(5,10,15,20-tetraphenylporphyrinato)cobalt(III) (CoIIICl(tpp)), have been observed at 4.2 K to room temperature. Based on the ESR parameters obtained, the paramagnetic species have been identified as two CoII(tpp) with different axial ligand effects and a previously reported cation radical, [CoIII(tpp)]2+·(Cl−)2. A correlation diagram among g, A, and axial ligation made from published data of cobalt(II) complexes has been successfully used for identification of the two trapped CoII(tpp) species: one is four-coordinate CoII(tpp) and the other five-coordinate CoIIX(tpp) in which X is presumably Cl−. Their electronic and molecular structures are discussed according to McGarvey’s theory. Finally, the formation mechanism of the three paramagnetic species in CoIIICl(tpp) is discussed, based on the results obtained from the single crystalline ESR measurements.
Studies of Acylamino Acid Monolayers by π-A curves. I. Acylamino Acids with Alkyl Side Chain
Authors: Takahashi Katashi , Tanaka Fudeko , Motomura Kinsi 
Published: July 2006

Abstract
In order to obtain some information regarding the behavior of amino acids at interfaces, the monolayers of N-acyl l-α-amino acids with alkyl side chains on water have been investigated by measuring the surface pressure vs. area curves at various temperatures. It has been found that N-octadecanoylglycine and N-octadecanoylalanine form the condensed monolayers over the whole surface pressure range measured, N-octadecanoylvaline forms the expanded monolayer at a lower surface pressure, and N-octadecanoylleucine and N-octadecanoylisoleucine collapse at high surface pressures. From the experimental results, it has been concluded that the amino acid residue with a long side chain occupies a large area at the air/water interface and interferes with the condensation of acylamino acid monolayer. It has also been found that the methyl esterification of amino acid residue makes the monolayer state unstable although it produces less significant effect than the increase in the alkyl chain length of amino acid residue.
A Fluorescence Study of the Adsorption of Water, Methanol, and Acetic Acid on an Activated Europium Ion-exchanged Mordenite
Authors: Arakawa Tsuyoshi , Takakuwa Midori , Shiokawa Jiro 
Published: July 2006

Abstract
The adsorption of water, methanol, and acetic acid on an activated Eu(III) ion-exchanged mordenite(Eu–M) has been studied by the measurement of the fluorescence of the Eu2+ ion which was produced by the dehydration at 500 °C. The emission peak of the Eu2+ ion sifted to a shorter wavelength on exposure to water and other simple molecules. The magnitude of the shift was correlated to the specific dielectric constant of the adsorbate. The quantum yield for the Eu2+ emission band after gas adsorption decreased in all cases. Also, the lifetime in the Eu2+-adsorbate system was shorter than that in an activated Eu–M sample. The rate constants for the radiationless transitions were more sensitive to the nature of the adsorbates, and the order of the quenching power was H2O&gt;D2O&gt;CH3OH.
Magnetic Circular Dichroism and Electronic States of Tetrachloroplatinate(II) and Tetrachloropalladate(II) Ions
Authors: Nakayama Kazuhiko , Komorita Takashi , Shimura Yoichi 
Published: July 2006

Abstract
The magnetic circular dichroism (MCD) spectra of K2PtCl4 and K2PdCl4 have been carefully remeasured over the visible-near UV region. The examination of the electronic absorption and the MCD spectra together with their Gaussian analyses strongly suggests that the band of K2PtCl4 at 30.3×103 cm−1 contains both Γ5(1Eg) and Γ3(1B1g)←Γ1(1A1g) transitions, and the band of K2PdCl4 at 21.1×103 cm−1 all three spin-allowed d-d transitions. The separation of the Γ2(1A2g) and Γ5(1Eg) excited states is considerably large with K2PtCl4 as compared with K2PdCl4. The MCD for the high-intensity absorption bands in K2PtCl4 is different from that reported previously. On the basis of new MCD result, the bands at 43.3 and 46.6×103 cm−1 have been assigned to d-p transitions, a2u(pz)←a1g(dz2) and eg(dxz,yz), respectively.
Spectrophotometric Determination of Lead, Zinc, and Cadmium after Extraction of Their Diethyldithiocarbamates into Molten Naphthalene and Replacement by Copper
Authors: Wasey Abdul , Bansal Raj K , Satake Masatada , Puri Bal K 
Published: July 2006

Abstract
A method is proposed for the extraction of lead, zinc, and cadmium as their diethyldithiocarbamates into molten naphthalene. These complexes are quantitatively extracted into molten naphthalene. After extraction, the solidified naphthalene containing the colorless complex of each of the above metals is dissolved in chloroform and the metal is replaced by copper(II) to develop a yellow color of copper(II) diethyldithiocarbamate. The absorbance is measured at 440 nm. Beer’s law is obeyed in the concentration range of 5.0–130.0 μg for lead, 3.0–60.0 μg for zinc, or 5.0–100.0 μg for cadmium in 10 ml of the final solution. The molar absorptivities (1 mol−1 cm−1) and Sandell sensitivities (μg/cm2) for lead, zinc, and cadmium are calculated to be 1.15×104, 0.0098, 1.11×104, 0.0059, and 1.15×104, 0.0098 respectively. Solutions containing 45.0μg of lead, 40.0μg of zinc, and 43.0μg of cadmium separately gave mean absorbances of 0.250, 0.620, and 0.440 with standard deviations of 0.0027, 0.0059, and 0.0038, respectively. Conditions have been decided for the determination of lead, zinc, and cadmium in some alloys and synthetic mixtures.
Preparation and Circular Dichroism Spectra of Cobalt(III) Complexes Containing an Optically Active NH2CH2CH(CH3)X−-N,X (X=S or Se) Ligand
Authors: Nakabayashi Kyoko , Doi Kaoru , Kojima Masaaki , Fujita Junnosuke 
Published: July 2006

Abstract
Several cobalt(III) complexes of the [Co(apS or apSe)(N4)]2+ type were prepared, where apS and apSe denote chiral 1-amino-2-propanethiolate-N,S and 1-amino-2-propaneselenolate-N,Se ligands, respectively, and N4 is (en=ethylenediamine)2, (R-chxn=(R,R)-1,2-cyclohexanediamine)2, or tren=tris(2-aminoethyl)amine. Their circular dichroism (CD) spectra were compared with one another and with those of complexes containing such ligands as achiral 2-aminoethanethiolate-N,S, 2-aminoethaneselenolate-N,Se or chiral 1-amino-2-propanolate-N,O (apO). The vicinal CD curves of S-apS obtained from CD spectra of the en and R-chxn complexes are similar and very large in magnitude in the d-d absorption band region. These curves are very similar to the CD spectrum of [Co(S-apO)(NH3)4]2+. The vicinal CD curve of S-apSe shows a similar pattern, but the magnitude is smaller than those of the S-apS and S-apO ligands. The vicinal effect of the protonated S-apSH ligand is much smaller compared with that of its conjugate base (S-apS) ligand. The tren complexes of S-apS and S-apSe exhibit CD spectra fairly different from the vicinal CD curves of the respective ligands in the d-d absorption band region.
Oxidative Degradation of Monosaccharides by Iron(III) Chlorides with a Near-UV to Visible Light under Aerobic Atmosphere
Authors: Araki Koji , Sakuma Masato , Shiraishi Shinsaku 
Published: July 2006

Abstract
Monosaccharides were oxidatively degraded by FeCl3 with irradiation of a near-UV to visible light under aerobic atmosphere. d-Fructose and d-arabinose were degraded to d-erythrose in a yield of more than 80 mol%. d-Glucose and d-mannose were at first degraded to d-arabinose, which was subsequently degraded to d-erythrose. While, d-ribose was directly degraded to d-erythrose and d-glyceraldehyde. The degradation processes were selective, and these reactions were shown to proceed via formation of an Fe(III)–monosaccharide complex. The kinetic data and other features of these reactions were also discussed.
Optically Active Anti Head-to-head Coumarin Dimer. A New Agent for the Determination of Enantiomeric Excess of Amines and Alcohols
Authors: Saigo Kazuhiko , Sekimoto Kazuhiro , Yonezawa Noriyuki , Ishii Fumio , Hasegawa Masaki 
Published: July 2006

Abstract
The enantiomeric excess of chiral amines was successfully determined by 1H NMR spectral and/or HPLC analysis of the diastereomeric diamides derived from optically active anti head-to-head coumarin dimer and the amines by lactone-ring-opening reaction without any condensing agent. This procedure also proved to be applicable to chiral alcohols.
Mössbauer Spectroscopic Study of Danalite, Fe4(BeSiO4)3S
Authors: Maeda Yonezo , Takashima Yoshimasa , Ishida Kiyotake 
Published: July 2006

Abstract
The Mössbauer spectra for danalite have been examined in the temperature range 4.2 to 321 K. The strong temperature dependencies of the Mössbauer parameters are explained on the basis of a ligand field at a tetrahedral site for iron.
Thermodynamic Studies of Halogenocadmium Complexes in Nonaqueous Solvents
Authors: Sasaki Yukio , Abe Kazuya , Takizawa Masao 
Published: July 2006

Abstract
The thermodynamic constants for the formation of halogenocadmium complexes in N,N-dimethylformamide (DMF) and propylene carbonate (PC) were calculated by potentiometric titration. The differences in the order of the stability among the halide ions (X−) for CdX42− in nonaqueous solvents and water were found to be dependent mainly on the enthalpy changes of transfer from water to DMF and PC for the formation of CdX42−.
Preparation and Properties of the New High Pressure Phase β-Zr(OH)PO4
Authors: Ono Akira , Okamura Fujio Peter 
Published: July 2006

Abstract
A new phase with chemical formula Zr(OH)PO4 was prepared above 1.5 GPa using a high pressure apparatus. Stability field of the compound was investigated, and X-ray study for a single crystal revealed that it is orthorhombic with space group Cmca or C2ca. The X-ray data are similar to those of Zr2O(PO4)2.
The Structure of Diaquatris[(methylthio)acetato]ytterbium(III), [Yb(CH3SCH2CO2)3(H2O)2]n
Authors: Ouchi Akira , Shimoi Mamoru , Kondo Satoshi 
Published: July 2006

Abstract
The crystal and molecular structure of the title complex has been determined by the use of single-crystal X-ray diffraction. The crystal of YbC9H19O8S3, F.W.=524.48, was monoclinic, with a space group of P21/a; a=12.501(6), b=25.096(9), c=10.788(2) Å, β=90.25(3)°, U=3384(2) Å3, Z=8, Dm=2.07(3), Dx=2.06 Mg m−3, and μ(Mo Kα)=6.20 mm−1. Both Yb(1) and Yb(2) are octa-coordinated and are in a dodecagedral geometry. They are in a linear polymer form, parallel to the c axis; Yb(1) and Yb(2) are arrayed in a line alternatively, bridged by one carboxylate ligand.
Reaction of Azobenzene with Dichlorocarbene in Phase-transfer-catalyzed System
Authors: Fujiu Tomohisa , Izumi Kazuo , Sekiguchi Shizen 
Published: July 2006

Abstract
Azobenzene (2) reacted with dichlorocarbene at 40 °C in the presence of several phase-transfer catalysts in a binary solvent (CHCl3–aqueous KOH), giving 2,2,3,3-tetrachloro-1-phenylaziridine (3), 1-phenyl-1,3-dihydro-2H–benzimidazol-2-one (4b), dichloroacetanilide (6), N,N′-diphenylurea (7), and trace amounts of 2-chloro-1-phenylbenzimidazole (8).
The Reaction of (Z)-2-(3-Oxo-1-propenyl)-2H-azirine Derivative with Molybdenum Carbonyl Complexes
Authors: Kobayashi Tomoshige , Nitta Makoto 
Published: July 2006

Abstract
The thermal reaction of (Z)-2,3-diphenyl-2-(2,3-diphenyl-3-oxo-1-propenyl)-2H-azirine with [Mo(CO)6] or [Mo(CO)3(MeCN)3] was reinvestigated to afford 2,3,5,6-tetraphenylpyridine along with the pyrroles and 1,3-oxazepine derivative. The formation of 1,3-oxazepine was demonstrated to be the purely thermal process. The 1,2,4,5-tetraphenyl-5-oxo-1,3-pentadienylnitrene complex was shown to give the pyridine and the pyrrole derivatives.
A New Preparation of Aliphatic Nitro Compounds by SH2′ Reactions of gem-Halo Nitro Compounds with Allyltributylstannane
Authors: Ono Noboru , Zinsmeister Klaus , Kaji Aritsune 
Published: July 2006

Abstract
α-Nitroalkyl radicals generated from gem-halo nitro compounds are reactive enough to undergo the carbon–carbon bond forming reaction with allyltributylstannane via radical chain processes, which provides a new method for the introduction of an allyl group into nitroalkanes.
Stereochemistry on the Catalytic Hydrogenation of 1-t-Butyl-4-methylenecyclohexane over Modified Raney Ni, Co, and Fe Catalysts
Authors: Imaizumi Shin , Murayama Hitoshi , Ishiyama Jun-ichi , Senda Yasuhisa 
Published: July 2006

Abstract
Contrary to a fresh catalyst, aged Raney Ni in ethanol provided exclusively a less stable product in the hydrogenation of the title compound. A similar stereoselectivity was observed over a catalyst which was refluxed in ethanol as well as that treated with carbon monoxide. These results indicate that the catalyst stored in ethanol is modified with carbon monoxide generated by the decomposition of the solvent.
Catalytic Functionalities of Molybdenum Catalysts Supported on Brazilian Bentonites
Authors: Schultz Gerhard W , Shimada Hiromichi , Yoshimura Yuji , Sato Toshio , Nishijima Akio 
Published: July 2006

Abstract
Two kinds of Brazilian bentonites were applied to supports of molybdenum catalysts to improve the catalytic selectivities of the hydrotreating catalysts. Separate model tests reactions showed that bentonite-supported molybdenum catalysts have higher activities for hydrocracking and hydrodesulfurization as compared to a standard Al2O3 supported catalyst, while the Al2O3 was superior to the bentonites for hydrogenation activity.
The Thermal Properties of Liquid Crystalline Materials Incorporating Piperazine Skeleton
Authors: Takenaka Shunsuke , Hirohata Toshiro , Kusabayashi Shigekazu 
Published: July 2006

Abstract
The thermal and electric properties of the homologous series of liquid crystalline materials incorporating a piperazine skeleton have been examined. Some piperazine compounds having a cyano group as the terminal function give rise to a wide-range nematic phase. On the other hand, the homologous series of α,α′-bis(4-alkyl-1-piperadinylimino)-p-xylenes and 1,4-bis(4-alkylbenzylideneamino)piperazines show strong smectic properties.
Conductivity and Ion Association of Some Diastereoisomeric Salts in Water. II. Ion Association between the Δ(−)589- or Λ(+)589-cis-Bis(ethylenediamine)dinitrocobalt(III) Ion and the Δ(+)589-(Ethylenediamine)bis(malonato)cobaltate(III) Ion and Its Temperature Dependence
Authors: Yokoyama Haruhiko , Nishimura Michio 
Published: July 2006

Abstract
The electric conductivities of aqueous solutions of the diastereoisomeric salts, Δ(−)589-cis-[Co(NO2)2(en)2]Δ(+)589-[Co(mal)2(en)] and Λ(+)589-cis-[Co(NO2)2(en)2]Δ(+)589-[Co(mal)2(en)](en=ethylenediamine and mal=malonate ion), have been measured at several temperatures from 15 to 35 °C. From the analysis of the conductivity data using the Pitts equation, it was found that the Δ- or Λ-cis-[Co(NO2)2(en)2]+ and Δ-[Co(mal)2(en)]− ions are appreciably associated in spite of the large monovalent ions and that the ion association is almost nonstereoselective and is endothermic in contrast to the exothermic ion association between Δ- or Λ-cis-[Co(NO2)2(en)2]+ and Δ-[Co(edta)]− (edta=ethylenediaminetetraacetate ion). By considering the obtained values of thermodynamic parameters of ion association and the significantly large Stokes radius of Δ-[Co(mal)2(en)]− compared to the effective radius estimated from its partial molar volume, this complex anion was presumed to have two hydration water molecules and to release one of them by associating with the complex cations. Possible short-range interactions between the complex ions were also discussed by considering the structures of the complex ions and the chemical properties of the ligands.
Decomposition of Crystalline Potassium Hexacyanoferrate(II) Trihydrate by Incident Energetic Argon Ions
Authors: Ohno Shin-ichi , Furukawa Katsutoshi 
Published: July 2006

Abstract
Ar+ ions in the energy range of 0.4 to 2 MeV was found to induce a chemical reaction in solid potassium hexacyanoferrate(II) trihydrate giving rise to Fe3+-ion clusters which have been evidenced by EPR observations. γ-Irradiations at high doses (&gt;109 rad) followed by heating (&gt;150 °C) were found to induce the same reaction. Irradiations with γ-rays, protons, or low-energy (&lt;40 keV) Ar+ ions alone did not induce this reaction, nor did a thermal activation. A possible mechanism for this reaction is discussed mainly from a qualitative point of view on the basis of experimental observations and results of atomic collision physics. It is concluded that the reaction is caused by a highly inelastic excitation of iron(II) in the complex which is accompanied with a simultaneous momentum transfer.
Molecular Dynamics Using Internal Coordinates. I. Infrared Spectra of Sulfur Dioxide
Authors: Hayashi Soichi , Oobatake Motohisa , Ooi Tatsuo , Machida Katsunosuke 
Published: July 2006

Abstract
A simulation method of molecular dynamics using internal coordinates for polyatomic molecule is described. The method permits intramolecular interaction to be expressed in terms of the internal coordinate, and produces translation, rotation, and vibration of molecule. As the first application, infrared spectra of sulfur dioxide both at gas and liquid phases are simulated by the method with an aid of the techniques proposed by Berens and Wilson. The spectrum at gas phase exhibits the pure rotational band and the vibrational-rotational bands for fundamental modes. The ν1 and ν2 vibrations show B-type band shape, and the ν3 mode shows A-type band shape, in accord with the experimental result and the selection rule for a prolate symmetrical top which may practically represent the molecule. At liquid phase, multiple peaks due to rotational structure disappeared, and single-peaked bands are simulated as expected. The method can be extended so as to describe more realistic intermolecular interactions than pairwise atom-atom potentials.