bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syntheses of Novel Hybrid Vitamin C Derivatives: Stability and Biological Activity
Authors: Morisaki Kazuo , Ozaki Shoichiro 
Published: June 2006

Abstract
A novel series of hybrid L-ascorbic acid (vitamin C) derivatives linking other biologically active substances glycolic acid, myo-inositol, and α-tocopherol (vitamin E) at the C-2 or C-3 hydroxyl group were synthesized, and their thermal stability and inhibitory activities against tyrosinase-catalyzed melanin formation, active oxygen species (AOS), and free radicals were evaluated in vitro. Among these derivatives, 2-O-carboxymethylascorbic acid had high thermal stability as well as moderate inhibitory activities against tyrosinase-catalyzed melanin formation, AOS, and free radicals compared to other typical inhibitors and scavengers. On the other hand, 3-O-carboxymethylascorbic acid was markedly unstable in aqueous solution. The 2-O-carbonylmethyl derivatives linking myo-inositol or vitamin E were susceptible to degrading, however the vitamin E derivative had stronger inhibitory activities against AOS and free radicals than free vitamin C.
Asymmetric Bis(alkoxycarbonylation) Reaction of Homoallylic Alcohols Catalyzed by Palladium in the Presence of Cu(I) Triflate Using the Chiral Bioxazoline Ligand
Authors: Ukaji Yutaka , Miyamoto Masanori , Mikuni Miho , Takeuchi Susumu , Inomata Katsuhiko 
Published: June 2006

Abstract
Palladium-catalyzed asymmetric intra- and intermolecular bis(alkoxycarbonylation) reactions of homoallylic alcohols in the presence of copper(I) triflate were achieved by using the chiral bioxazoline ligand, (S,S)-4,4′-dibenzyl-4,4′,5,5′-tetrahydro-2,2′-bioxazole, under normal pressure of carbon monoxide and oxygen at 25 °C to give the corresponding optically active γ-butyrolactones in 19—65% ee.
Reactivities and Site-Selectivities of Hydrolyses of ATP and UTP Promoted by Metal Complexes of Adenine-Linked Di-2-pyridylamine Derivatives
Authors: Sawa Masaaki , Ogino Kenji , Tagaki Waichiro 
Published: June 2006

Abstract
The reactivities and the site-selectivities of the hydrolyses of ATP and UTP by the catalysts of the metal complexes of adenine-linked di-2-pyridylamine ligands, (Py)2N–(CH2)n–Ade (L: n = 3, 4, 5, and 6), were examined. It was found that these adenine–dipyridylamine coordinated Cu2+ complexes (with 2 : 1 ratios of [CuII(L)]2+ : ATP or [CuII(L)]2+ : UTP) were more reactive for the hydrolyses of ATP and UTP than the complexes of ligands containing other metal ions (Mg2+, Ni2+, and Zn2+) at 40 °C and pH 7.3 (HEPES buffer), as reflected in much higher product ratios of ADP/AMP and UDP/UMP than those of Cu2+ alone. The observed high reactivity and selectivity are interpreted in terms of the base-base stackings between an adenine moiety of ATP or an uracil moiety of UTP and an adenine of the ligands, and of the selective coordination of Cu2+ to oxide ions in phosphate residues in the ternary complexes of ligand–Cu2+–ATP. The Cu2+-complex of di-2-pyridylamine having no adenine moiety, which is the active center of [CuII(L)]2+, promoted the hydrolyses of ATP and UTP less efficiently than the aquacopper(II) ion. The number of spacer methylene groups of the ligands influenced the hydrolytic activity of the Cu2+-complexes of these adenine–dipyridylamine ligands. The complexes of [CuII(L-4)]2+ and [CuII(L-5)]2+ were the most reactive and site-selective for the hydrolyses of ATP and UTP, respectively.
Base-Catalyzed Acyl Exchange Reactions of N,O-Diacyl-o-aminophenols. Substituent and Temperature Effects on the Equilibrium Constants
Authors: Sakurai Tadamitsu , Nagaoka Tohru , Kamiya Jun , Inoue Hiroyasu 
Published: June 2006

Abstract
Substituent and temperature effects on the equilibrium constants for the triethylamine-catalyzed acyl exchange reactions of N-(substituted benzoyl)-O-acetyl-o-aminophenols have been investigated by 1H NMR spectroscopy. It was found that the standard enthalpy change ΔH° in acyl exchange processes, estimated from temperature dependence of the equilibrium constant, correlates well with the standard free energy change ΔG° which was used as a measure of the relative stability of isomer pairs, while the standard entropy change ΔS° is approximately constant (−6 ± 2 J K−1 mol−1) irrespective of the substituents in benzoyl introduced. The finding of enthalpy-controlled acyl exchange reactions confirms that the relative stability of a given isomer pair is determined by the difference in electrostatic force of attraction between the amide nitrogen with a partial positive charge and the ester carbonyl oxygen having a partial negative charge in both isomers.
Modification of Transport Properties of Ion Exchange Membranes.XV. Preparation and Properties of Cation Exchange Membranes Having a Single Cationic Charged Layer on the Membrane Surface by Sulfonyl–Amide Bonding
Authors: Takata Kuniaki , Yamamoto Yoshihisa , Sata Toshikatu 
Published: June 2006

Abstract
In order to prepare an excellent monovalent cation permselective cation exchange membrane, a polyethyleneimine (PEI) layer was formed with sulfonyl–amide bonding between PEI and sulfonyl chloride groups on one surface of the membrane. Two methods were tried: 1) one surface of the membrane reacted with PEI and the remaining sulfonyl chloride groups were hydrolyzed, and 2) after one surface of the sulfonyl chloride groups had been hydrolyzed, the other surface of the membrane was reacted with PEI and the remaining sulfonyl chloride groups were hydrolyzed. The cation exchange membranes, which had been prepared using both methods, had excellent monovalent cation permselectivity, low electrical membrane resistance and high current efficiency for the long-term electrodialytic concentration of seawater. The reacted amount of PEI on the membrane was about 10% of the cation exchange capacity.
Kinetics of a Thermolysin-Catalyzed Peptide Formation Reaction in Acetonitrile–Water
Authors: Kunugi Shigeru , Yoshida Masumi 
Published: June 2006

Abstract
Thermolysin-catalyzed peptide condensation reactions from acylamino acids and amino acid amides were studied in an acetonitrile (MeCN)–water mixed solvent in a homogeneous system. A kinetic analysis of the condensation reaction was performed by taking into account the simultaneous, solvent-induced, gradual inactivation of the enzyme. Although the dependence on the concentration of the carboxyl component gave linear double-reciprocal plots, that on the amine component at 70% MeCN showed an apparent substrate inhibition profile. An analysis of the apparent Km and kcat parameters for both components at 40% MeCN indicated that the condensation reaction proceeded by a random Bi–Bi mechanism. The Km values were estimated to be 5.5 mM for Cbz–Phe and 110 mM for LeuNH2, and kcat was 4—5 s−1. The Km values for Cbz–Phe and LeuNH2 were also evaluated at 70% MeCN to be 5 and 100—150 mM, respectively. This indicates that the catalytic property of this enzyme is not significantly influenced by the existence of a higher concentration of such an organic solvent, except for the second nonproductive binding of the amine component.
Influence of Size of Dispersed Silica Particles on Preparation of Thick Silica Films by Using Electrophoretic Sol–Gel Deposition
Authors: Nishimori Hideki , Tatsumisago Masahiro , Minami Tsutomu 
Published: June 2006

Abstract
Monodispersed silica particles, which ranged from 0.14 to 0.42 μm in diameter, were prepared by the sol–gel method. These particles were first separated from original sols, and dried, heat-treated, and then re-dispersed in a mixture of ethanol, water, and triethoxy(methyl)silane. Thick silica films without micro-cracks were formed by electrophoretic deposition of the particles on a stainless steel sheet in the re-dispersed sols. The weight of the silica films deposited was increased with increasing particle size at a given applied voltage. On the other hand, density of the films was increased with decreasing particle size. When the particle size was 0.32 μm in diameter, crack-free films of ca. 20 μm in thickness were prepared after heat treatment at 800 °C for 1 h.
Crystal Structures and Physical Properties of 1,6-Diaminopyrene-p-chloranil (DAP-CHL) Charge-Transfer Complex. Two Polymorphs and Their Unusual Electrical Properties
Authors: Goto Hirotoshi , Fujinawa Tasuku , Asahi Hidemasa , Inabe Tamotsu , Ogata Hironori , Miyajima Seiichi , Maruyama Yusei 
Published: June 2006

Abstract
A combination of 1,6-diaminopyrene and p-chloranil gives two kinds of 1 : 1 charge-transfer complex crystals from a benzene solution. The α-form is triclinic, space group , a = 8.963(1), b = 9.112(2), c = 6.730(1) Å, α = 99.59(1), β = 99.65(1), γ = 114.43(1)°, V = 476.0(1) Å3, and Z = 1; the β-form is also triclinic, space group , a = 8.123(3), b = 9.708(3), c = 6.791(2) Å, α = 110.73(2), β = 108.89(2), γ = 79.11(3)°, V = 472.3(3) Å3, and Z = 1. In both crystals, the donors and acceptors are neutral, and stack alternately. The main difference between the α- and β-forms is in the overlapping mode. Both crystals are electrically insulating at the initial states. The α-form single crystal, however, undergoes and irreversible conductivity change upon mild heating (&lt; 380 K) or fracture of the crystal into powder. In both cases, the conductivity change amounts to 106 to 108, and the resultant solids are highly conducting semiconductors. Structural, optical, magnetic, and solid-state NMR studies suggest that the low-resistance state mainly comprises neutral molecules, despite its high conductivity. The resistivity of β-DAP-CHL also decreases upon heating to above 400 K, while fracture of the crystal has no effects. The resistivity change in β-DAP-CHL is considered as simple ionization of a part of the components.
Enzyme-Mediated Enantioselective Protonation to Enolates in an Aqueous Medium
Authors: Ohta Hiromichi 
Published: June 2006

Abstract
An enzyme sometimes provides a entirely hydrophobic chiral reaction field to a synthetic substrate. This is one of the most characteristic features of an enzyme compared to ordinary chemical catalyst. Taking advantage of being able to carry out a reaction of a prochiral compound in this special pocket, it is possible to prepare an optically active product via asymmetric protonation in an aqueous medium. Two such examples are demonstrated in this article, i.e., asymmetric hydrolysis of enol esters, and asymmetric decarboxylation of α-aryl-α-methylmalonic acid to give optically active ketones and α-arylpropionic acids, respectively. Some related reactions are described as well.
Structures and Magnetic Properties of Some Fe(III) Complexes with Hexadentate Ligands: in Connection with Spin-Crossover Behavior
Authors: Hayami Shinya , Matoba Takashi , Nomiyama Shuichi , Kojima Takahiko , Osaki Susumu , Maeda Yonezo 
Published: June 2006

Abstract
Several iron(III) complexes with the different hexadentate Schiff-base ligands of N4O2 donor sets were synthesized; these are 1 : 2 condensation products of linear tetramines (3,3,3-, 3,2,3-, 2,3,2- or 2,2,2-tetramine) and salicylaldehyde, acetophenone or benzophenone derivatives. Their crystal structures, Mössbauer spectra, magnetic susceptibilities, electronic spectra and cyclic voltammetry of the complexes were examined. The X-ray structures of the single crystals of [Fe(3,2,3-sal2tet)]NO3 (1), [Fe(3,2,3-sal2tet)]BPh4 (2), [Fe(3,2,3-mpk2tet)]PF6 (3), [Fe(2,3,2-sal2tet)]ClO4 (4), [Fe(2,3,2-3MeO-sal2tet)]ClO4 (5), [Fe(2,3,2-mpk2tet)]ClO4 (6), [Fe(2,3,2-bpk2tet)]ClO4 (7), and [Fe(2,2,2-bpk2tet)]ClO4·EtOH (8) were determined.
The moieties of the iron atoms of (1), (2), and (3) with 3,2,3-tetramine, and (7) with 2,3,2-tetramine were pseudo octahedral with trans-FeN4O2 geometry. Those of (4), (5), and (6) with 2,3,2-tetramine, and (8) with 2,2,2-tetramine were cis-FeN4O2 geometry. The iron(III) complexes (1), (2), (3), and (7) were in the low-spin state, and the iron(III) complexes (4), (5), (6), and (8) were in the high-spin state.
In the electronic spectra, the wave lengths of the LMCT bands for the low-spin complexes were longer than those for the high-spin complexes. The values of redox potentials for the low-spin states were suggested to be 0.12 V more negative than those for the high-spin states.
(Remark: This summary is partially truncated in the html because it exceeds the limit of the system (4000 characters per note). The complete text is given in the pdf.)
cis–trans Isomerism among the Octahedral Diaquabis(optically active C-substituted ethylenediamine)nickel(II) Complexes and Their Thermal Reaction Products. An Explanation for a Variety in Colors and Stereochemistry of Lifschitz Complexes
Authors: Ihara Yoshinori , Sakino Tomomi , Ishikawa Mieko , Koyata Takanori 
Published: June 2006

Abstract
The solid-phase thermal reactions of trans-diaquabis(diamine)nickel(II) complexes (trans-[Ni(diamine)2(H2O)2]X2) were investigated by means of TG/DTA and DSC, and high-temperature electronic spectrometry, where the diamine is an optically active diamine such as (1S,2S)-1,2-diphenyl-1,2-ethanediamine or (S)-4-methyl-1,2-pentanediamine, and X is Cl−, Br−, or NO3−. Several complexes were peculiarly transformed into cis-[NiX2(diamine)2] upon thermal deaquation-anation, and then isomerized to trans-[NiX2(diamine)2] upon further heating. The results were in contrast to the reactions of the complexes with the corresponding racemic diamines which underwent a simple deaquation-anation, retaining an original trans configuration. The differences must come from a slight difference in the conformation of diamine ligands between trans-[Ni(R-diamine)(S-diamine)(H2O)2]X2 which is obtained for the rac-diamines and trans-[Ni(R- or S-diamine)2(H2O)2]X2 which is obtained for the optically active diamines.
Development of Chemical Substances Regulating Biofilm Formation
Authors: Yamada Akihiro , Kitamura Hitomi , Yamaguchi Kaori , Fukuzawa Seketsu , Kamijima Chiyuki , Yazawa Kazunaga , Kuramoto Makoto , Wang Gui-Yang-Sheng , Fujitani Yasuyuki , Uemura Daisuke 
Published: June 2006

Abstract
The chemical substances which regulate biofilm formation were examined, and a bioassay system which uses marine bacteria with adhering properties was developed. This bioassay system is suitable for screening crude extracts from marine organisms. Using this system, those substances which regulate biofilm formation were isolated from marine organisms. For example, bis(deacetyl)solenolide D was obtained from the marine sponge Psammaplysilla purpurea. Novel nitroalkanes were also isolated from the Okinawan sponge Callyspongia sp. Ethyl N-(2-phenylethyl)carbamate isolated from the marine bacteria SCRC3P79 (Cytophaga sp.) inhibited biofilm formation. Furthermore, the N,N-dichloro, isocyanide, isothiocyanate, and dithiocarbamate derivatives of 2-(4-nitrophenyl)ethylamine, significantly inhibited the growth of marine attaching bacteria. Interestingly, most of the marine sponges examined contained anti-biofilm compounds, such as benzoic acid, aeroplysinin-I, and bromoageliferin.
A New Convenient Synthesis of 1,2′-Biazulenes by Photolysis of 2-Diazo-1,3-dicyanoazulen-6(2H)-one with Azulene Derivatives
Authors: Lin Shih-Jue , Jiang Shuan-Ya , Huang Tian-Chyuan , Dai Cheng-Shyan , Tsai Pai-Feng , Takeshita Hitoshi , -Lin Yun-Sha , Nozoe (the late) Tetsuo 
Published: June 2006

Abstract
A photolysis of 2-diazo-1,3-dicyanoazulen-6(2H)-one in the presence of azulene derivatives in anhydrous ethyl acetate solution afforded 1,2′-biazulene derivatives, which are otherwise difficult to obtain, in good yields, nearly 90% or more. Accompanying by-products, 1,3-dicyanoazulen-6-ol and 2,5′-biazulene derivatives, were also characterized.
High 1,2-Asymmetric Induction in Radical Reactions: Radical Addition to γ-Hydroxy α,β-Unsaturated Carboxylic Esters and Sulfones
Authors: Ogura Katsuyuki , Kayano Akio , Akazome Motohiro 
Published: June 2006

Abstract
High 1,2-asymmetric induction was realized by the addition of a 1-hydroxy-1-methylethyl radical to conformationally flexible (E)-γ-hydroxy α,β-unsaturated carboxylic esters and sulfones (1 and 2, respectively). Upon the irradiation (&gt; 290 nm) of (E)-1 and benzophenone in 2-propanol, the 1-hydroxy-1-methylethyl radical was generated in situ and added to (E)-1 with high anti-stereoselectivity. The bulkier is the γ-alkyl group of (E)-1, the higher does the selectivity become. Similarly, a radical addition to the acetates of (E)-1 and (E)-2 proceeded stereoselectively in an anti fashion, whereas (Z)-2 exhibited syn-stereoselectivity. The mechanism for these stereoselective radical additions is discussed.
Synthesis and in Vitro Evaluation of 5-closo- and 5-nido-Orthocarboranyluridines as Boron Carriers
Authors: Imamura Ken-ichiro , Yamamoto Yoshinori 
Published: June 2006

Abstract
Sugar-part modified closo-carboranyluridines, 5-(o-carboran-1-yl)-2′,3′-dideoxy-3′-thiauridine 5 and 5-(o-carboran-1-yl)-2′,3′-dideoxy-2′α-phenylthiouridine 6, were synthesized. These newly synthesized closo-carboranyluridines, 5 and 6, and previously synthesized 5-(o-carboran-1-yl)uridine 1 were converted to the corresponding nido-carboranyluridines 18, 19, and 17, respectively. Water-solubility of nido-type 17 was about 100 times higher than that of its closo-counterpart 1. Water-solubilities of sugar modified nido-types 18 and 19 were about 1000 times higher than those of their closo-counterparts 5 and 6 . Cytotoxicities of the nido-types (17 and 19) were about 10 times lower than those of the corresponding closo-counterparts (1 and 6, respectively). Cellular uptake of the nido-types (17 and 19) was in the level similar to that of the closo-counterparts (1 and 6, respectively), although it is often believed that cellular uptake of hydrophilic carboranes (nido-forms) is much lower than that of lipophilic closo-carboranes.
Ruthenium-Catalyzed Addition of Carbon–Hydrogen Bonds in Aromatic Ketones to Olefins. The Effect of Various Substituents at the Aromatic Ring
Authors: Sonoda Motohiro , Kakiuchi Fumitoshi , Chatani Naoto , Murai Shinji 
Published: June 2006

Abstract
To obtain further insight into the new ruthenium-catalyzed reaction of carbon–hydrogen bonds in aromatic ketones with olefins, the effect of various substituents at the aromatic ring is examined. Reaction of o-methylacetophenone with triethoxyvinylsilane (2) in the presence of [Ru(H)2(CO)(PPh3)3] (3)as the catalyst gave the 1 : 1 addition product in quantitative yield. Similarly, the ketone having an o-CF3 group gave the coupling product 9 in 92% yield. However, ortho substituents such as OMe, F, and CN, seem to react with and kill the catalyst so that no efficient reaction was attained. In the cases of the reactions of p-methoxy- and p-fluoroacetophenones with 2, the corresponding 1 : 2 addition products were obtained as the major products. In the cases of m-substituted acetophenones, two different C–H bonds at the ortho positions are available. The C–C bond formation preferentially occurred at the sterically less congested positions. Exceptions are the reactions of m-methoxy- and m-fluoroacetophenones, in which the C–C bond formation took place preferentially at the more congested position. This may be due to the coordination of oxygen or fluorine atom to ruthenium. The factors controlling these selectivities are discussed.
Dried Urushi Lacquer Film Comprizing Several New Types of Inorganic Linkage and Urushiol Matrix
Authors: Shiihara Isao 
Published: June 2006

Abstract
This paper concerns the hardening mechanism of urushi lacquer. The author wished to propose an entirely new mechanism for the room-temperature hardening of urushiol in this natural resin. An investigation of the unit reactions correlated to the mechanism indicated that the catechol moiety of urushiol and metalhydroxides play an important role in hardening.
According to the results, the structure of one component of urushiol as “acetone powder”, obtained from raw urushi sap, was clearly determined. On this basis, it is disclosed that the polymerization of urushiol does not depend on the opening of the sesquiterpene double bond, but is mainly associated with a new type of inorganic ionomer bonding, such as silanolate and carbohydroperoxide–calcium hyroxide, –magnesium hydroxide or –other metal hydroxide combinations’ hydrogen bonding bridges with the urushiol matrix.
Analysis of Microelectrode-Detected ESR (MEDESR) Signals of Nitroxide Radicals in Electrolyte Solutions
Authors: Yokoyama Hidekatsu , Sato Toshiyuki , Ohya-Nishiguchi Hiroaki , Kamada Hitoshi , Kasai Nahoko , Matsue Tomokazu 
Published: June 2006

Abstract
Microelectrode-detected ESR (MEDESR) spectroscopy is a technique that is employed to observe magnetic resonance on the basis of an impedance change of electrodes. The characteristics of MEDESR for nitroxide radicals in electrolyte solutions were analyzed. MEDESR signals were obtained at zero bias-current, suggesting that modulation of the bias-current derived from ESR would not generate MEDESR signals. A good linear relationship between the MEDESR signal intensity and the applied power over a range of up to 150 mW was obtained. The frequency characteristics of the magnetic field modulation indicated that a simple thermal phenomenon would not cause an impedance change in MEDESR. When the radical was distributed on only the electrode surface, no signals were detected. The MEDESR spectra of a nitroxide solution, located outside the electrolytic cell, was detectable. These findings suggest that since MEDESR signals are irrelevant to the radicals in an electrical double layer, they are derived from some changes in the microwaves in the whole resonator. It is speculated, however, that the detecting mechanism of MEDESR is not a simple process of rectifying detection of a microwave change by resonant absorption like in conventional ESR, because the signal intensity of MEDESR is proportional to the irradiation power, and not to the square root as in the conventional ESR.
Biomechanical and Histomorphometric Analyses of Monocortical Screws at Placement and 6 Weeks Postinsertion
Authors: Huja S. S. , Rao J. , Struckhoff J. A. , Beck F. M. , Litsky A. S. 
Published: June 2006

AbstractMaxillofacial screws are increasingly being used in orthodontics to provide anchorage for tooth movement. The objective of this study was to determine the biomechanical stability as well as the bone tissue response of screws at 6 weeks postinsertion in a canine model. Seven skeletally mature male dogs received 102 screws (2 × 6 mm or 2 × 8 mm) at predetermined sites. Twenty screws became loose or were lost during the 6-week undisturbed healing period. Forty-eight screws were randomized for mechanical testing and 34 for histology. Peak pullout strength was recorded and ∼80-μm sections were examined for histomorphometric parameters. Statistical analyses were conducted by analysis of variance and Tukey-Kramer method. Mean ± SE peak pullout strengths for the various sites ranged from 153.5 ± 37.6 N to 389.3 ± 32.5 N with no significant (P &lt; .05) differences at immediate placement and 6 weeks postinsertion. Bone contact ranged from 79% to 95%. Histomorphometric analyses indicated higher bone formation rate in the mandible than in the maxilla and a gradient of decreasing turnover with increasing distance from the screw interface. These results provide the clinical orthodontist with an estimate of the holding power of these screws and an understanding of early biological healing response associated with self-drilling screws.
Upper tolerance limit for the largest observation from censored samples
Authors: Takada Yoshikazu 
Published: June 2006

AbstractThis paper deals with obtaining an upper tolerance limit for a largest observation X(n) in an ordered sample of size n from a continuous distribution where the first m observations X(1) < X(2) < … < X(m), l ≤ m < n, have been observed. A criterion of “goodness” of tolerance limit is developed, and a method is given to obtain the best tolerance limit. This method is applied to exponential and Pareto distributions.