bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Triplet State of Nitrospiropyran in Their Photochromic Reaction
Authors: Sakuragi Masako , Aoki Kousou , Tamaki Takashi , Ichimura Kunihiro 
Published: July 2006

Abstract
The effects of intermolecular and intramolecular triplet quenchers and sensitizers on the photochromism of nitrospiropyran have been examined in order to clarify the role of the triplet state (3A*) as well as that of the excited singlet state (1A*). The rates of photocoloration and fatigue were significantly affected: the quenchers retarded both rates, while the sensitizers retarded the former but enhanced the latter rate. It can be concluded that more than 90% of the total amount of photomerocyanin is generated from 1A* in the photostationary state and that fatigue proceeds mainly through 3A*.
Circuit Resonance Energy. On the Roots of Circuit Characteristic Polynomial
Authors: Mizoguchi Noriyuki 
Published: July 2006

Abstract
The circuit characteristic polynomial plays an important role in the theory of circuit resonance energy of polycyclic conjugated molecules. Although in the use of circuit resonance energy it is essential that the circuit characteristic polynomial has real roots, the definition of circuit characteristic polynomial does not ensure that the roots of this polynomial are real numbers. It is proved that the circuit characteristic polynomial for any circuit in a polycyclic conjugated molecule has no imaginary roots if this molecule is a nonfused polycyclic conjugated molecule or a fused bicyclic system.
The Determination of a Small Amount of a Biological Constituent by Use of Chemiluminescence. XVI. High-Sensitive Detection of Proteins by an Ion–Exchange Chromatograph–Chemiluminescence Detector System
Authors: Hara Tadashi , Tsukagoshi Kazuhiko , Tsuji Haruyuki 
Published: July 2006

Abstract
An ion-exchange chromatograph–chemiluminescence detector system was developed by connecting a high-resolution ion-exchange column with a chemiluminescence detector using a 1,10-phenanthroline–hydrogen peroxide–copper(II) system which was first developed by the authors for the detection of protein. A sodium tetraborate–hydrochloric acid buffer solution was found to be suitable for the development of well-defined chromatogram without lowering the resolution of an ion-exchange column and the sensitivity of a chemiluminescence detector. The elution of protein was carried out by a gradient elution method. According to the present method, two mixture samples of ovalbumin–trypsin inhibitor (from soybean, crude) or bovine serum albumin–trypsin inhibitor (from soybean, crude)–trypsin inhibitor (from chicken egg white), which were too dilute to detect by a UV detector, gave chromatograms similar as in UV detection.
Direct Phosphonation of Naphthalene and Phenanthrene with Trialkyl Phosphites via Photochemical Electron Transfer
Authors: Yasuda Masahide , Yamashita Toshiaki , Shima Kensuke 
Published: July 2006

Abstract
Direct photophosphonations of naphthalene and phenanthrene with trialkyl phosphites occurred in the presence of electron acceptors to give arylphosphonates and dihydroarylphosphonates.
The Synthesis of Benzofuroquinolines. VI. A New Synthesis of Benzofuro[2,3-c]quinoline Derivatives
Authors: Yamaguchi Seiji , Oh-hira Yutaka , Yamada Minoru , Michitani Hitomi , Kawase Yoshiyuki 
Published: July 2006

Abstract
Two benzofuro[2,3-c]quinoline derivatives, 6-methylbenzofuro[2,3-c]quinoline and 6(5H)-benzofuro[2,3-c]quinolinone, were synthesized by the condensation of 2-amino-2′-hydroxybenzophenone with chloroacetone, ethyl bromoacetate, or chloroacetonitrile. The benzofuroquinolinone, thus obtained, was converted to 6-chloro and 6-cyanobenzofuro[2,3-c]quinolines.
Photoinduced Organic Transformation. Selective Synthesis of Ethylene Glycol or Formic Acid and Methyl Formate from Methanol in the Presence of Hydrogen Peroxide
Authors: Shimizu Yuichi , Sugimoto Shun’ichi , Kawanishi Shunichi , Suzuki Nobutake 
Published: July 2006

Abstract
The photoinduced transformation of methanol (MeOH) has been investigated in the presence of H2O2. Ethylene glycol (EG) was selectively produced by UV light irradiation of the N2-saturated MeOH and the selectivity was 85–94% below 3 ml h−1 of H2O2 feeding rate (f). The quantity of EG reached the maximum at f=5 ml h−1 and the quantum yield was 0.73. EG was produced through the dimerization of hydroxymethyl radicals formed by the abstraction of hydrogen atom from MeOH by hydroxyl radical which was formed by the photolysis of H2O2. On the other hand, formic acid (FA) and methyl formate (MF) were selectively produced by UV light irradiation of the O2-bubbled MeOH and the combined selectivity was about 99% in the f range of 1–8 ml h−1. The quantities of FA and MF reached the maximum at f=5 ml h−1 and their quantum yields were 1.36 and 0.69, respectively. FA was mainly produced through the decomposition of hydroperoxyhydroxymethane formed by the abstraction of hydrogen atom from MeOH by hydroxymethyldioxy radical which was formed by the reaction of hydroxymethyl radical with oxygen, and MF through the reaction of MeOH with FA formed.
The Amino–Imino Tautomerization of the 2-Aminopyridine–Acetic Acid System in Isooctane
Authors: Inuzuka Kozo , Fujimoto Akira 
Published: July 2006

Abstract
The UV absorption spectra of 2-aminopyridine were measured in isooctane (2,2,4-trimethylpentane) containing various amounts of acetic acid at room temperature; the temperature dependence (20–−80°C), of the spectra was also determined, while the concentration of acetic acid was maintained constant. An additional shoulder band appeared around 335 nm in the spectra obtained when the acetic acid concentration was higher than 1×10−2 mol dm−3. The band corresponding to the 335 nm band was observed for monomethyl-substituted 2-aminopyridine. The 335 nm band was assigned to the π–π* transition of the (E)-2(1H)-pyridinimine moiety in the 2-aminopyridine-acetic acid complex. The proton transfer from acetic acid to 2-aminopyridine in the complex may be difficult energetically in the ground state.
The Preparation of Alkyltrimethylammonium–Kanemite Complexes and Their Conversion to Microporous Materials
Authors: Yanagisawa Tsuneo , Shimizu Toshio , Kuroda Kazuyuki , Kato Chuzo 
Published: July 2006

Abstract
Single layered polysilicate kanemite (NaHSi2O5·3H2O) was allowed to react with alkyltrimethylammonium chloride solutions to form alkyltrimethylammonium–kanemite complexes. During the organic intercalation, the SiO2 layers in the complexes were condensed to form three-dimensional SiO2 networks. The calcined products of the complexes had micro pores 2–4 nm in diameter, and the surface areas were ca. 900 m2g−1. The pore size of the calcined products was altered with the variation in the alkyl-chain length of the alkyltrimethylammonium ions employed.
Translational Energy Distributions and Emission Cross Sections of the Excited Hydrogen Atom Produced in e–SiH4 Collisions
Authors: Tsuboi Toshiyuki , Nakashima Keiji , Ogawa Teiichiro 
Published: July 2006

Abstract
The translational energy distributions of H* (n=3, 4) produced in e–SiH4 collisions were obtained by measuring the Doppler profiles of the Balmer-α and β lines with a Fabry–Perot interferometer. There are three major components in the translational energy distributions of H* (n=3, 4). The first component lies in the 0–3 eV region, the second one peaks at 2–3 eV, and the third one lies at above 4 eV. Thus, dissociation of SiH4 for the formation of H* (n=3, 4) should proceed through three different groups of Rydberg states. The emission cross sections were determined separately for H* (n=3, 4) with the translational energy of 0–2, 2–4, 4–6, 6–8, and 8–10 eV, respectively.
Catalytic Isomerization of Trimethylbenzenes over a Graphite–Sulfuric Acid
Authors: Tsuchiya Susumu , Fujii Kenji , Mitsuno Tadashi , Sakata Yoshihisa , Imamura Hayao 
Published: July 2006

Abstract
The isomerization of 1,2,3- and 1,2,4-trimethylbenzene took place over a graphite–sulfuric acid to form 1,2,4- and 1,2,3-trimethylbenzene, respectively, but that of 1,3,5-trimethylbenzene was not observed.
Infrared Spectra of SiO2 Coating Films Prepared from Various Aged Silica Hydrosols
Authors: Muroya Masaaki 
Published: July 2006

Abstract
Measurements have been made of the vibrational absorption bands of silica films. The results have been used to examine the importance of the polymerization of silica. Seven other absorption bands, which are related to the Si–O group, were clearly found in the region from 1300 to 400 cm−1. A band at a wave number of 1069 cm−1 increased with increasing the viscosity of the hydrosol. The band at 974 cm−1 was substantially sensitive in intensity to the heat-treatment and the rehydration of silica film, can be assigned to the Si–O stretching vibration of the surface silanol since the intensity of its band is influenced by both the heat-treatment(dehydration) and rehydration.
New Curvularin-Type Metabolites from the Hybrid Strain ME 0005 Derived from Penicillium Citreo-viride B. IFO 4692 and 6200
Authors: Lai Sheng , Shizuri Yoshikazu , Yamamura Shosuke , Kawai Kazuaki , Furukawa Hideyuki 
Published: July 2006

Abstract
Four new curvularin-type metabolites (11-α-methoxycurvularin, 11-β-methoxy curvularin, 11,12-dihydroxycurvularin, and 12-hydroxy-10, 11-trans-dehydrocurvularin) have been isolated from the mycelium of the hybrid strain ME 0005 derived from Penicillium citreo-viride B. IFO 4692 and 6200. And β-hydroxycurvularin, the biologically active principle from Alternaria tomato, was identified as 11-β-hydroxycurvularin.
Polypeptide Synthesis Using the S-Alkyl Thioester of a Partially Protected Peptide Segment. Synthesis of the DNA-Binding Domain of c-Myb Protein (142–193)–NH2
Authors: Hojo Hironobu , Aimoto Saburo 
Published: July 2006

Abstract
A method for polypeptide synthesis using S-alkyl thioester of a partially protected peptide segment has been developed. The DNA-binding domain of c-Myb protein (142–193) was synthesized by this method to estimate its usefulness. The partially protected peptide segments, Boc–[Lys(Boc)143,144,160]–c-Myb protein(142–163)–SCH2CH2CONH2 and [Lys(Boc)171,182,192]–c-Myb protein(164–193)–NH2, were highly purified from peptides obtained by a solid-phase method. The thioester in the carboxyl component of the peptide segment was converted to the corresponding p-nitrophenyl ester in the presence of silver ions and p-nitrophenol and then the two segments were condensed. The coupling reaction proceeded almost completely yielding a highly-purified product after removal of Boc groups.
Conformation in Solution of the Fully Toxic Domain of Heat-Stable Enterotoxin (STp) Produced by Enterotoxigenic Escherichia coli
Authors: Ozaki Hiroshi , Kubota Hirokazu , Sato Takashi , Hidaka Yuji , Tamaoki Haruhiko , Kobayashi Yuji , Kyogoku Yoshimasa , Sugimura Takashi , Tai Akira , Shimonishi Yasutsugu 
Published: July 2006

Abstract
Heat-stable enterotoxin (STp) produced by a porcine strain of enterotoxigenic Escherichia coli is a peptide of 18 amino acid residues. The full toxicity is generated by a core peptide of 13 amino acids from residue 5 to 17 (STp(5–17)). Detailed conformational analysis of STp(5–17) was performed by NMR spectroscopy and distance geometry calculations. The tertiary structure of STp(5–17) was found to have a right-handed spiral fold throughout the whole molecule which was stabilized by the network of disulfide linkages and hydrogen bonds. This folding pattern was demonstrated in both organic and aqueous solutions.
Small-Angle X-Ray Scattering Study of Cytochrome Oxidase from Beef Heart and Its Complex with Cytochrome c Using Contrast Variation Method
Authors: Morimoto Yukio , Sato Mamoru , Kato Tatsuhisa , Tanaka Nobuo , Katsube Yukiteru , Tanaka Masashi , Ozawa Takayuki 
Published: July 2006

Abstract
The structure of cytochrome oxidase from beef heart and its complex with cytochrome c were investigated in solution by X-ray small-angle scattering. The contrast variation method was applied to the present analysis. The radii of gyration and maximum dimensions were estimated to be 54 and 165 Å for the cytochrome oxidase and 56 and 165 Å for the complex, respectively. A model of the dimer was constructed so as to interpret the X-ray scattering data well. It was concluded that cytochrome c is bound to the hydrophilic surface of the enzyme near the edges of the ellipsoidal molecule, and that detergent molecules exist on the surface of the central parts of the enzyme.
An Ab Initio Molecular Orbital Study on Twisting in Silyl-Substituted Ethylene Cation Radicals
Authors: Takahashi Ohgi , Morihashi Kenji , Kikuchi Osamu 
Published: July 2006

Abstract
Twisting in two silyl-substituted ethylene cation radicals, the cation radicals of vinylsilane (1) and vinylidenebissilane (2), were investigated by ab initio UHF calculations with the 3-21G and 3-21G(*) basis sets. Both 1+· and 2+· were found to have twisted equilibrium structures, the twist angle being 29° and 42°, respectively. The planarization barriers evaluated for 1+· and 2+· are about 1 and 7 kcal mol−1, respectively. The planar and 90°-twisted forms of 2+· have comparable energies. The hyperconjugation of the C-Si bonds is reflected in the calculated molecular structures.
Product Selectivity Affected by Cationic Species in Electrochemical Reduction of CO2 and CO at a Cu Electrode
Authors: Murata Akira , Hori Yoshio 
Published: July 2006

Abstract
Electroreduction of CO2 and CO was studied with a copper electrode in hydrogencarbonate solutions of various cations. Product selectivity was greatly affected by cationic species as well as HCO3− concentration. H2 evolution prevailed over CO2 reduction in Li+ electrolyte, whereas CO2 reduction was favorable in Na+, K+, and Cs+ solutions. C2H4 formation became greater than CH4 with increase of the cation size, i.e. with sequence of Li+, Na+, K+, Cs+. The variation of the product selectivity caused by cationic species is rationalized by the difference of outer Helmholtz plane (OHP) potential. The OHP potential will vary with cationic species in accordance with the degree of specific adsorption. The concentration of H+ at the electrode will depend upon the OHP potential, since H+ is a charged species. This difference of pH at the electrode will lead to the variation of product selectivity.
Effect of Ether Oxygen on Proton Transfer and Aggregation Reactions of Amines in Water by Ultrasonic Absorption Method
Authors: Nishikawa Sadakatsu , Haraguchi Hiroshi , Fukuyama Yasuyo 
Published: July 2006

Abstract
Ultrasonic absorption coefficients in the frequency range from 6.5 to 220 MHz have been measured in aqueous solutions of 3-ethoxy- and 3-butoxypropylamine as functions of their concentrations along with the sound velocity at 2.5 MHz and the density. In a 3-ethoxypropylamine solution, only one relaxational absorption has been observed up to 3.0 mol dm−3. The cause has been clarified to be due to a proton-transfer reaction of the amine from the concentration dependences of the relaxation frequency and the relaxational amplitude. The rate and thermodynamic parameters have been determined and reasonable values have been obtained as a diffusion-controlled reaction. In the solution of 3-butoxypropylamine, another relaxation process in addition to that due to the proton-transfer reaction has been observed in the concentrations of more than 0.5 mol dm−3. This relaxation process has been attributed to a perturbation associated with an aggregation reaction, 4A↔A4, from the concentration dependences of the relaxation frequency and the relaxational amplitude of the absorption. The rate and thermodynamic constants for the proton-transfer and aggregation reactions have been determined. It has been found from a comparison of the results for the two solutions and others reported previously that the introduction of ether oxygen into amine molecules has little influence on the proton-transfer reaction, but prevents the formation of aggregates due to the hydrophobic interaction. It has also been seen from the results of 3-butoxypropylamine solutions that the butoxyl group has a fairly high ability of hydrophobic interaction and that nonionized molecules form aggregates in the aqueous solution.
Broadening of the Proton Magnetic Resonance Spectra of Sulfonate Anions by Ion Pairing with Paramagnetic Chromium(III) Complexes
Authors: Iida Masayasu , Yokoyama Haruhiko 
Published: July 2006

Abstract
The paramagnetic line broadening of both the 1H spectra of CH3SO3− and (CH2SO3)22− was observed in aqueous solutions including chromium(III) complexes such as [Cr(en)3]3+ (en=ethylenediamine), [Cr(phen)3]3+(phen=1,10-phenanthroline), and lel,lel,lel-[Cr(chxn)3]3+ (chxn=trans-1,2-cyclohexanediamine). The dependence of the line broadening on the concentration of chromium(III) complexes was attributed to contact ion-pair formation. The distances between the Cr atom and the H atoms of the anions in contact ion pairs were derived in order to discuss their configurations. The anions were considered to be in contact with the complex ions through one or two sulfonate groups directed toward the Cr atom in the open space along the C3-axis of the complex or in hollow regions between the ligands.
Formation of Acrylaldehyde by Vapor-Phase Aldol Condensation I. Basic Oxide Catalysts
Authors: Ai Mamoru 
Published: July 2006

Abstract
Vapor-phase aldol condensation of formaldehyde with acetaldehyde to form acrylaldehyde was studied with various oxides supported on silica gel using 35% formalin as the source of formaldehyde. The silica gel unsupported catalyst prepared from colloidal silica showed a relatively high activity and selectivity to form acrylaldehyde. The catalytic activity was markedly enhanced by the incorporation of a basic or amphoteric oxide into the silica gel, while it fell with the incorporation of an acidic oxide such as P2O5 or B2O3. The highest yields of acrylaldehyde were obtained with the Si–Mg, Si–Li, Si–Na, and Si–Zn oxide systems. Effects of reaction variables were also studied using a catalyst with an Si : Mg atomic ratio of 100 : 10.
Crystal Structure of 2′-O-Succinyladenosine 3′,5′-(Cyclic)phosphate Monohydrate: A Model Compound to Study Protein–Nucleic Acid Interactions
Authors: Padmaja Natarajan , Ramakumar Suryanarayana Rao , Viswamitra Mysore A 
Published: July 2006

Abstract
The crystal and molecular structure of 2′-O-succinyladenosine 3′,5′-(cyclic)phosphate monohydrate has been determined by X-ray diffraction techniques. The compound crystallizes in the orthorhombic space group P212121; Z=4 with a=5.633(1), b=15.853(2), c=20.607(3) Å. The final R value is 0.029. The adenine base is protonated at N(1). The base is in syn conformation (χ=−95.8°) with respect to the sugar, which has a C(3′)-endo-C(4′)-exo pucker (4T3). A six-membered ring formed by phosphate group and ribose shows chair conformation. The succinic acid moiety, which resembles side chains of certain amino acids, is found to have a bent skeleton. The cyclic AMP, which is known to play diverse roles in many metabolic processes, forms the nucleotide portion of the title compound. The succinic acid moiety that is covalently linked to this nucleotide in the present compound, shows direct and water mediated interactions with phosphate and base nitrogens of the nucleotide respectively. Such compounds can therefore serve as models to study the protein–nucleic acid interactions, which play a central role in many of the biological processes.
Palladium-Catalyzed Synthesis of N-Benzoyl-2-arylethenesulfonamides from [2-(Benzoylsulfamoyl)ethyl]pyridinium Chloride and Aryl Halides
Authors: Hirooka Syuzi , Tanbo Yuzi , Takemura Katsuya , Nakahashi Hironori , Matsuoka Tsuyoshi , Kuroda Shigeyasu 
Published: July 2006

Abstract
A new, general synthesis of N-benzoyl-2-arylethenesulfonamides by the reaction of aryl halides including heteroaryl halides with [2-(benzoylsulfamoyl)ethyl]pyridinium chloride in the presence of palladium acetate is described.
Spin-Trapping Studies on the Reaction of Iron Complexes with Peroxides and the Effects of Water-Soluble Antioxidants
Authors: Kohno Masahiro , Yamada Masako , Mitsuta Keiichi , Mizuta Yokio , Yoshikawa Toshikazu 
Published: July 2006

Abstract
Using ESR spin-trapping techniques we measured the levels of free radical species generated from six different systems (hypoxanthine-xanthine oxidase, iron(II)–hydrogen peroxide, iron(III)–hydrogen peroxide, iron(II)–t-butyl hydroperoxide, iron(III)–t-butyl hydroperoxide, and catalase (CAT)–t-butyl hydroperoxide). Six types of radicals (O2−·,·OH, ·H, ·CH3, (CH3)3CO·, and (CH3)3COO·) were detected as spin adducts of spin traps 5,5-dimethylpyrroline 1-oxide (DMPO) or 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS). Quantitative analysis of the levels of generated radicals by means of an ESR instrument also presents important information regarding the reduction of peroxides [hydrogen peroxide (H2O2) or t-butyl hydroperoxide (ROOH)] by iron(II) or iron(III) as well as catalase. In addition, the scavenging potencies of different water-soluble antioxidants such as l-ascorbic, d-isoascorbic, gallic, sorbic, and protocatechuic acids were evaluated in terms of their ability to reduce the peaks of spin adducts.
On the Facilitation Effect of Neutral Macrocyclic Ligands on the Ion Transfer across the Interface between Aqueous and Organic Solutions. I. Theoretical Equation of Ion-Transfer-Polarographic Current-Potential Curves and Its Experimental Verification
Authors: Matsuda Hiroaki , Yamada Yutaka , Kanamori Kazuo , Kudo Yoshihiro , Takeda Yasuyuki 
Published: July 2006

Abstract
A theoretical equation of the reversible polarographic current-potential curves for the ion transfer across the aqueous/organic interface facilitated by the neutral macrocyclic ligand present in the o-phase is derived without any limitation on the magnitude of distribution constant of the ligand. In two limiting cases, which have been employed in common experimental practice, i.e., (A) the bulk concentration of cation, c*M, in the aqueous phase &gt;&gt; that of ligand, c*L, in the organic phase and (B) the reverse condition, c*M&lt;&lt;c*L, the equation of current-potential curves becomes the same in form as that of reversible D. C. polarographic waves. It is shown that the limiting current is controlled by diffusion of ligand in the organic phase for (A) and of cation in the aqueous phase for (B) and, on the other hand, the half-wave potential depends on c*M for (A) and on c*L for (B). Furthermore, an analysis method to determine the complex formation constants in the organic phase (and in the aqueous phase for favorable cases) from the concentration dependence of the half-wave potential is presented. The theoretical predictions are verified experimentally using dibenzo-18-crown-6 and 18-crown-6 as macrocyclic ligands and sodium, cesium, barium, and oxonium ions as transferred cations.
Studies on the Secondary Structure of Bradykinin in Aqueous Solution. Syntheses, Circular Dichroism Spectra, and Biological Activities of Bradykinin Analogs Containing 5-Aminovaleric Acid Residue
Authors: Hashimoto Chikao , Tamaki Makoto , Sofuku Shosuke , Muramatsu Ichiro 
Published: July 2006

Abstract
Eight bradykinin analogs containing 5-aminovaleric acid residue were synthesized by a solution method. Based on the consideration concerning their CD spectra, the presence of an intramolecular 3→1 hydrogen bond between the carbonyl oxygen of Ser6 and the amide proton of Phe8, an intramolecular 4→1 hydrogen bond between the carbonyl oxygen of Pro2 and the amide proton of Phe5, and a salt bridge between the guanidino group of Arg1 and the carboxyl group of Arg9, was proposed for the secondary structure of bradykinin in aqueous solution. The biological activities of these analogs depend on the presence of both Phe residues at positions 5 and 8, and Arg residues at positions 1 and 9. No correlation between the biological activities and the secondary structure could be found.