bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic Study of Casein Micelle Formation Observed by a Stopped-Flow Apparatus
Authors: Nishikawa Sadakatsu , Tatsusue Misa , Inoue Tadaomi , Yasunaga Tatsuya 
Published: July 2006

Abstract
The time dependent optical density changes were observed when aqueous solutions (Tris buffer) of sodium casein from milk were mixed with those of calcium chloride by a newly constructed stopped-flow apparatus which was controlled by an 8-bit microcomputer. Two approaches for single exponential decay curve analysis were used, i.e. the Guggenheim analysis and an analysis according to a linear relation between the time and the logarithm of the corresponding absorbance change, at a concentration range between 0.02–0.05 wt% of the casein and in that between 10–30 mmol dm−3 of calcium chloride at 25°C. The same time constants and reaction amplitudes were obtained from both analyses of the decay curves. The obtained rate parameters were found to be concentration dependent. The result was interpreted by a stepwise reaction mechanism for the formation of a casein aggregate. The rate-determining step was speculated to be the first step of the larger molecular aggregate of the casein according to the concentration dependence of the apparent rate constant and the reaction amplitude. The rate constant for the casein micellization could be approximately estimated as being of the order of 104 mol−1 dm3 s−1 at 25°C. The effects of NaCl, MgCl2, and CaBr2 on casein micelle formation were also examined; it was kinetically confirmed that only calcium cations played an important role in the formation of the casein micelle.
Photoelectron Emission Study of Iron(II) and Cobalt(II) Complexes in Aqueous Solution. Reorganization Energies
Authors: Watanabe Iwao , Ono Kaori , Ikeda Shigero 
Published: July 2006

Abstract
The photoelectron emission threshold energies of FeII and CoII complexes in aqueous solutions have been determined. The values could be successfully used for obtaining the reorganization energies in the one-electron oxidation reaction of these complexes. The obtained reorganization energies were found to be correlated with the rate constants of the electron-self-exchange reactions of FeII/FeIII and CoII/CoIII.
Conformational Stability of V-Amyloses and Their Hydration-Induced Conversion to B-Type Form as Studied by High-Resolution Solid-State 13C NMR Spectroscopy
Authors: Saitô Hazime , Yamada Junko , Yukumoto Tohru , Yajima Hirofumi , Endo Ryuichi 
Published: July 2006

Abstract
We have recorded 13C NMR spectra of several preparations of amorphous samples, V-amyloses and their hydrates to gain insight into their relative stability and subsequent hydration-induced conformational change. It was found that the 13C NMR line width of the iodine complex prepared as a precipitate in aqueous solution was the narrowest among these preparations, including the iodine complex formed from cast film. It is noteworthy that these V-amyloses are not always stable when they are equilibrated in an atmosphere of 96% R. H. in a desiccator and converted to B-type form, consistent with previous observation by Senti and Witnauer (J. Am. Chem. Soc., 70, 1438 (1948)). 2H NMR line shape and spin-lattice relaxation times were measured for partially deuterated V and B-type amylose samples containing DMSO-d6 and deuterium oxide, respectively, to explore the dynamics of the DMSO and water molecules bound to the polymer chains. It is unlikely that any drastic conformational change such as unfolding followed by refolding and plausible change of handedness is caused by such mild physical treatment as humidification. Therefore, it appears that the resulting B-type form should be ascribed to a left-handed single helix as a consequence of a slight modification of V-amylose, in contrast to the previous interpretation based on the data of X-ray diffraction and NMR studies. Gelation mechanism of amylose gel based on this view is also discussed.
Ring Transformation of 1-Substituted 3,5-Dinitro-4-pyridones to 4-Nitro-5(2H)-isoxazolone by Hydroxylamine
Authors: Ariga Masahiro , Tohda Yasuo , Nakashima Hiroko , Tani Keita , Mori Yutaka , Matsumura Eizo 
Published: July 2006

Abstract
New ring transformations of 3,5-dinitro-1-(4-nitrophenyl)-4-pyridone and its homologues with hydroxylamine were found to give 4-nitro-5(2H)-isoxazolone. These results were rationalized by double ring transformations in sequence. The fact that the 4-position of the 4-pyridone behaved as an electrophlic site was the first example in this series of ring transfomations, and was caused by the alpha-effect of the reagent. Some reactions of the isoxazolone were carried out.
Studies on Synthetic Ionophores. IX. X-Ray Crystal Structure Analysis of Potassium, Rubidium, and Cesium Salts of a Synthetic Carboxylic Ionophore
Authors: Kasuga Noriko , Nakahama Seiichi , Yamaguchi Kazuo , Ohashi Yuji , Hori Kayako 
Published: July 2006

Abstract
X-Ray crystal structure data are presented for potassium, rubidium, and cesium salts (2, 3, and 4) of 2-[[2-[2-[2-[2-[2-[2-[2-(2-hydroxyethoxy)phenoxy]ethoxy]phenoxy]ethoxy]phenoxy]ethoxy]phenoxy]methyl]benzoic acid (1). The crystals of the potassium salt (2) monohydrate dichloroform solvate (2·H2O·2CHCl3) are triclinic, space group P\bar1 with two molecules in the unit cell dimensions a=14.517(1), b=16.380(1), c=13.315(1) Å, α=72.313(8)°, β=117.313(8)°, γ=120.853(5)°. R=0.102 for 6351 observed reflections. The crystals of 3·H2O·CHCl3 are monoclinic, space group P21⁄a with four molecules in the unit cell dimensions a=24.085(6), b=13.068(2), c=13.983(4) Å, β=105.402(32)°. R=0.068 for 5112 observed reflections. The crystals of 4·H2O·CHCl3 are monoclinic, space group P21⁄n with four molecules in the unit cell dimensions a=24.412(7), b=13.075(2), c=14.077(4) Å, β=106.743(31)°. R=0.071 for 6153 observed reflections. The backbones of 2, 3, and 4 form pseudocycles by head-to-tail hydrogen bonding between the terminal carboxylato and hydroxyl groups (O···O distance, 2.672, 2.699, and 2.706 Å, respectively). The conformations about C–C and C–O bonds are gauche and trans respectively, except for two of the C–O bonds which are gauche to make the pseudocyclic backbone bend like the seam of a tennis ball resulting in the formation of cavities fitted for the size of each cation.
Preparation of Some Polyfunctional Indenes and Indanones: The Reaction of Mercapto-Substituted Cyclopropenium Salts with Alcohols and Thiols
Authors: Yoshida Hiroshi , Takahashi Youko , Kinoshita Hiroaki , Ukishima Sadao , Ogata Tsuyoshi , Matsumoto Kiyoshi 
Published: July 2006

Abstract
The reaction of 1-methylthio-, 1-(4-methylphenylthio)-, or 1-t-butylthio-2,3-diphenylcyclopropenium salts with alcohols, phenols, and thiols in the presence of triethylamine at around 80°C gave 1H-indene-1-thiol derivatives in fair to moderate yields. In contrast, the same reactions at room temperature afforded 1-alkylthio- or arylthio-1-cyclopropene derivatives together with a small amount of the 3-isomer. Some 1-isomers were separated as pure crystals and produced the corresponding indenes in quantitative yields when heated. Kinetic studies of the ring-opening of cyclopropenes suggested a vinylcarbene intermediate based on the small effects of solvent polarities and phenoxyl substituents on the reaction rates. The reaction of diphenylcyclopropenone with thiol in the presence of trifluoroacetic acid yielded 1H-indene-1,3-dithiol detivatives via a 1,3-bis(alkylthio)-or (arylthio)-1-cyclopropene intermediate. On acidic hydrolysis of 3-alkoxyindenes and on heating of 3-allyloxy- and 3-(2-propynyloxy)indenes, polyfunctionally-substituted indanones were obtained in good yields.
Dehydrooligopeptides. XIII. Selective Enzymatic Hydrolysis of N-Protected α-Dehydroglutamic Acid Diesters and Their Analogs Using Papain as Catalyst
Authors: Shin Chung-gi , Takahashi Nobuyuki , Seki Masashi 
Published: July 2006

Abstract
Since the α-ester of α,γ-dimethyl N-benzyloxycarbonyl-α-dehydroglutamate (ΔGlu) was found to be hydrolyzed using papain, a variety of N-protected α-dehydroglutamates and their analogs, both esters of which were the same or different from each other, were newly synthesized and subjected to a similar hydrolysis. Although the substrates, with bulkier ester group at the γ- as well as α-positions, were found to become difficult to hydrolyze, the kind and size of the N-protecting group did not effect the hydrolysis. Moreover, it was found that the length of side chain of the substrate greatly influenced hydrolysis. The present study suggests that papain may become a useful tool for the hydrolysis and coupling of ΔGlu with α-amino acid or peptide.
The Properties of the Multistage Bioreactor Constructed by the LB Technique
Authors: Ohnishi Michihiro , Ishimoto Coe , Seto Jun’etsu 
Published: July 2006

Abstract
A multistage bioreactor consisting of organic ultrathin layers was successfully realized by immobilizing glucose oxidase and glucoamylase by the Langmuir–Blodgett technique (LB technique). Starch as the substrate was quickly converted into gluconic acid and hydrogen peroxide as the products in this bioreactor via the intermediate, glucose. The rate of the sequential reactions was electrochemically measured. This rate increased proportionally with increasing the concentration of starch, and also increased with increasing the amount of glucose oxidase in the LB film. This bioreactor, however, decayed soon. The reason of this decay was considered to be the structural conversion of the LB layers with glucoamylase. The multistage bioreactor constructed by the LB technique will be used not only as a super small-sized, rapid bioreactor or biosensor but also as an investigating means of the reconstitution of membrane enzyme and biomembrane.
ENDOR and TRIPLE Studies of Diphenyl Nitroxide (DPNO)
Authors: Yamauchi Jun , Fujita Hideo , Deguchi Yasuo 
Published: July 2006

Abstract
ENDOR and triple resonance (GTR) of diphenyl nitroxide (DPNO) were observed in solution; it was demonstrated that DPNO is an interesting model radical forming a three-spin system (electron and 1H- and 14N-nuclear spins). The detected 14N-ENDOR belongs to one of the smallest hyperfine cases (AN=0.9653 mT). Its optimum temperature was 210 K, higher than that of the 1H, which is due to the large anisotropic hyperfine interaction of 14N. In the 1H-ENDOR spectra the effect of cross relaxation was observed, as in the case of the 14N-ENDOR lines; their temperature variations of intensity showed two maximum regions, one due to the optimum energy relaxation in the 14N-spin system and the other due to the energy relaxation inherent in the 1H-spin system. In the triple studies new phenomena were pointed out: An enhancement saturation effect due to the large hyperfine interaction and an intensified enhancement or de-enhancement effect due to the cross relaxation.
Cobalt(III) Complexes with [N6−nXn]-Type Ligands. VII. Preparation and Properties of Isomers of the (Salicylamidato)cobalt(III) Complexes with Tris(2-aminoethyl)amine, Triethylenetetramine, and Ethylenediamine Ligands
Authors: Toyota Eiko , Yamamoto Yoshihisa 
Published: July 2006

Abstract
Title complexes of t- and p-[Co(A)(tren)]Cl2·H2O, t- and p-[Co(C)(tren)]Cl·H2O, cis-β1 and β2-[Co(A)(trien)]Cl2·2H2O, cis-β1-[Co(C)(trien)]Cl·H2O, cis-β1-[Co(D)(trien)]Cl·H2O, [Co(A)(en)2]Cl2·H2O, [Co(C)(en)2]Cl·H2O, and [Co(D)(en)2]Cl·H2O have been obtained from a reaction mixture of [CoCl2L]Cl·H2O [L: tren, trien, or (en)2], Ag2O, and salicylamide.
(Remark: Graphics omitted.)
Separations of the A-, C-, and D-type complexes, and of the geometrical isomers of t- and p- or cis-β1 and β2 were attempted by using Dowex 50W-X2 column chromatography. Distinction of the A-, C-, and D-type complexes is described in the IR, 1H, 13C NMR, and absorption spectra; the solubility in DMSO; and the electric conductivities in aqueous solutions. The formation ratio of the A-, C-, and D-type complexes has been dependent upon the pH of the reaction mixture. The chemical shifts (δ=113–115) of the C-l carbon signals for the A-type complexes are at a higher field than those (δ=117–122) of the C- and D-type complexes. The ε values (3400–3700) of the charge transfer band at ca. 340 nm in the absorption spectra for the A-type complexes are greater than those (2500–3000) of the C- and D-type complexes. The C-type and D-type complexes are a linkage isomer. A characteristic property of the linkage isomer has been observed in the absorption and 13C NMR spectra as well as the solubility in DMSO.
Ferromagnetic Spin-Coupling between Gadolinium(III) and Copper(II) Ions in Discrete Binuclear Gd(III)–Cu(II) Complexes
Authors: Sakamoto Masatomi , Hashimura Masayuki , Matsuki Kimihiro , Matsumoto Naohide , Inoue Keiji , Okawa Hisashi 
Published: July 2006

Abstract
Three discrete binuclear gadolinium(III)–copper(II) complexes (CuGd(fsadien)NO3·5H2O (1), CuGd(hsapn)NO3·3H2O (2), and [Gd(pvm)3Cu(A)] (3)) have been synthesized; we use the notation H4fsadien=N,N′-bis(3-carboxysalicylidene)diethylenetriamine, H4hsapn=N,N′-bis(3-hydroxysalicylidene)-1,2-propanediamine, Hpvm=dipivaloylmethane (2,2,6,6-tetramethyl-3,5-heptanedione), and H2A=4-(6-methyl-8-oxo-2,5-diazanona-1,5,7-trienyl)imidazole. Magnetic susceptibility measurements (4.2–300 K) have revealed that the spin coupling between the Gd(III) and Cu(II) ions is ferromagnetic with coupling constants J=+2.3 cm−1 for (1), +5.7 cm−1 for (2), and +0.5cm −1 for (3), on the basis of the spin-Hamiltonian H=−2JSGd·SCu.
Studies of the Hydrous Zirconium(IV) Oxide Ion Exchanger. II. The Rate of Isotopic Exchange of Sodium Ions between the Exchanger in the Na+ Form and Aqueous Solutions
Authors: Inoue Yasushi , Yamazaki Hiromichi , Narita Tomonori 
Published: July 2006

Abstract
The rate of the isotopic exchange of Na+ between hydrous ZrIV oxide in the Na+ form and aqueous solutions of sodium salts was determined radiochemically. The rate is controlled by particle diffusion, film diffusion, or both, according to the conditions. The exchange rate is controlled by particle diffusion, when the exchanger particles are large (radius, 171 μm), the solutions are more concentrated than 0.1 mol dm−3 Na+ and the flow rate through the exchanger particles is high, whereas under the opposite conditions film diffusion is the rate-controlling step. The activation energies of Na+ diffusion are 30±3 and 18.9±0.5 kJ mol−1 for particle and film diffusion, respectively.
Preliminary Polarographic Studies of Sulfur and Selenium Solutions in Hydrazine Hydrate
Authors: Srivastava S K , Babu K S Chandra , Srivastava O N , Singh Dharam 
Published: July 2006

Abstract
The dropping mercury electrode polarographic behavior of sulfur and selenium solutions in hydrazine hydrate has been studied in highly alkaline aqueous solution containing supporting electrolyte of 0.1 M ammonium tartrate (1 M=l mol dm−3). Both the sulfur and selenium revealed a composite anodic–cathodic waves. The values of E1⁄2 for sulfur and selenium solutions, taken from the cathodic wave of the polarograms corresponded to E1⁄2=−0.78 and −1.03 V vs. SCE respectively. The effect of mercury pressure and concentration of depolarizer on the relative magnitude of the wave heights has also been studied on the basis of typical reactions involved at DME in this solvent medium. No maxima supressor was used in the present study for both cases.
Electrochemical Reactions at Sacrificial Electrodes. VII. Synthesis of Some Unique Mercury(II) Alkoxides and Glycolates and Their Coordination Compounds
Authors: Banait Jagtar Singh , Devi Rani , Singh Baljit 
Published: July 2006

Abstract
The electrochemical oxidation of malononitrile, diethyl malonate, ethyl cyanoacetate, cyanoacetamide, ethyl acetoacetate, and acetylacetone has been carried out in acetonitrile at sacrificial mercury anode using tetrabutylammonium chloride as supporting electrolyte. The products of these reactions have been identified by elemental analysis and IR spectral studies and are found to be mercury(II) alkoxides/glycolates. Electrochemical oxidation of these compounds in the presence of ligands like 1,10-phenanthroline and 2,2′-bipyridyl yields coordination compounds of these alkoxides/glycolates. All these reactions have been found to proceed with a very high current efficiency.
Enhanced Production of Formic Acid by Halobacterium halobium MMT22 by Reduction of Hydrogencarbonate in Aqueous Solution
Authors: Khan Mirza Mohammad Taqui , Bhatt Jayshree 
Published: July 2006

Abstract
Enhanced production of formic acid was observed by reduction of hydrogencarbonate in aqueous solution by Halobacterium halobium MMT22. A one and half fold increase in the production of formic acid was observed in the presence of ascorbic acid as electron donor and [Ru(Bipy)3]2+ as photosensitizer.
Structural Study of the Two Phases of Tetrakis(methylseleno)tetrathiafulvalene (TSeC1–TTF)
Authors: Nakano Chikako , Wang Ping , Mori Takehiko , Maruyama Yusei , Inokuchi Hiroo , Yamochi Hideki , Saito Gunzi 
Published: July 2006

Abstract
The crystal structure of the low-melting point phase (L-phase) of a single component organic semiconductor, TSeC1–TTF, is determined and compared with that of the high-melting point phase (H-phase). The intracolumnar overlap mode and the calculated intermolecular overlap integrals are slightly larger in the L-phase, to which is ascribed the low resistivity of the L-phase. The L-phase, however, does not have two-dimensional networks of intercolumnar Se···Se contacts, which exist in the H-phase. This may be associated with the difference of the melting points.
Deuterium Isotope Effects on Aromatic Carbon-13 Chemical Shifts. III. One-, Two-, and Three-Bond Isotope Effects on the 13C Chemical Shifts of 3-Substituted Pyridines
Authors: Nakashima Yasuki , Ban Sadanori , Itoh Satoru , Takahashi Kensuke 
Published: July 2006

Abstract
The one-, two-, and three-bond deuterium isotope effects (1Δ, 2Δ, and 3Δ) on the 13C chemical shifts of 3-substituted pyridines are reported. 1Δ, 2Δ, and 3Δ are correlated with the 13C chemical shifts of the observed carbons. 1Δ, show a linear correlation with the 13C chemical shifts with a positive slope. On the other hand, 2Δ and 3Δ show linear correlations with the negative slopes. They can thus be interpreted in terms of the π-electron density change by the substituent and the electron release effects by carbons one and two bonds apart from deuterium, respectively.
Facile Production of d-Histidine by Asymmetric Transformation of l-Histidine
Authors: Shiraiwa Tadashi , Shinjo Kazuyuki , Masui Yoko , Ohta Atsushi , Natsuyama Hisashi , Miyazaki Hideya , Kurokawa Hidemoto 
Published: July 2006

Abstract
An asymmetric transformation from l-histidine [l-His] to d-His was achieved by using salicylaldehyde as a catalyst for epimerization, and (2R, 3R)-tartaric acid as a resolving agent, in acetic acid. Treatment of the obtained salt with triethylamine in methanol gave d-His with 100% optical purity in 95% yield based on the starting l-His.
3-Aryl-3-butenoic Acids and Their Esters: Practical Synthesis from Diketene by the Palladium-Catalyzed Grignard Coupling Reaction and Application as Monomers for the Radical Copolymerization with Styrene
Authors: Itoh Kenji , Harada Tatsumi , Nagashima Hideo 
Published: July 2006

Abstract
Treatment of arylmagnesium bromide with an equimolar amount of zinc chloride followed by the reaction with diketene in the presence of a catalytic amount of PdCl2(PPh3)2 provided an improved synthetic method for 3-aryl-3-butenoic acids in a large scale. Application as a monomer for the substituted polystyrenes is exemplified by the copolymerization of methyl 3-phenyl-3-butenoate with styrene.
Reaction of Dichlorotriphenylphosphorane with Bis(trimethylsilyl) Peroxide. A New Method for the Formation of Electrophilic Chlorine Source
Authors: Shibata Kazusato , Itoh Yukinori , Tokitoh Norihiro , Okazaki Renji , Inamoto Naoki 
Published: July 2006

Abstract
Reactions of dichlorotriphenylphosphorane with bis(trimethylsilyl) peroxide in the presence of some organic compounds have been found to give chlorinated products. Aromatic hydrocarbons bearing electron-donating substituents give the corresponding monochloroarenes, while an enol silyl ether is converted into α-chloro ketone. The mechanism is briefly discussed.
Selective Hydroxymethylation of Emodin
Authors: Pal Tarasankar , Pal Anjali 
Published: July 2006

Abstract
Electrochemical oxidation of 1,3,8-trihydroxy-6-methylanthraquinone, emodin, in dry alkaline methanol under a constant current of 0.05 A for 10 h under an applied potential difference of 15 V at room temperature resulted, for the first time, in an efficient and selective hydroxymethylation at C-2. The structure of the product was established from the detailed spectral analyses of its trimethyl ether and tetraacetylated derivative.
Some 13C and 15N NMR Studies on 1,8-Bis (dimethylamino) Naphthalene and Two of Its Salts
Authors: Grech E , Stefaniak L , Ando Isao , Yoshimizu Hiroaki , Webb Graham A 
Published: July 2006

Abstract
13C and 15N NMR data are reported for 1,8-bis(dimethylamino)naphthalene (DMAN) and two of its salts in both the solid state and solutions in CD3CN. Only the 15N results are sufficiently sensitive to show the presence of the fully protonated form of DMAN in the solid state and of a partially protonated structure in solution.
Studies on Stigmasterol Liquid Membranes
Authors: Srivastava M L , Shukla Nikhil K 
Published: July 2006

Abstract
Cellulose acetate supported stigmasterol liquid surfactant membrane has been characterized by measuring membrane potentials, using NaCl solutions of different concentrations. Fixed charge density, φ\barX, permselectivity, Ps, have been estimated from ionic transport numbers. Variation of membrane potential with pH and concentration of NaCl solution has also been examined.
Synthesis and Application of 5-Arylazothiophene Derivatives
Authors: Sabnis Ram Wasudeo , Kazemi Ghadir , Rangnekar Dinesh Wamanrao 
Published: July 2006

Abstract
Synthesis of 5-(hetoarylazo or arylazo)thiophene derivatives (6a–g) was achieved by diazotization of ethyl 5-amino-2,4-bis(ethoxycarbonyl)-3-thiopheneacetate (3) using nitrosyl hydrogensulfate, coupling with suitable heterocyclic hydroxy and N,N-dialkyl-substituted arylamines which resulted in thiophene azo dyes. The key intermediate 3, used as the diazonium component, was synthesized in one pot and in excellent yield from diethyl 3-oxopentanedioate, sulfur and ethyl cyanoacetate following the Gewald Synthesis. The dyes when applied as disperse dyes on polyester fibres gave excellent results.
New Syntheses and Physical Properties of p-Alkylcalix[n]arenes
Authors: Shinkai Seiji , Nagasaki Takeshi , Iwamoto Koji , Ikeda Atsushi , He G-X , Matsuda Tsutomu , Iwamoto Masakazu 
Published: July 2006

Abstract
Calix[n]arenes (n=4, 6, and 8) bearing long p-alkyl groups (R=hexyl and dodecyl) have been synthesized by “direct” acylation of the p-position followed by silane reduction. The method is convenient and the yields are higher than those reported so far. Among them, p-hexanoylcalix[4]arene showed a curious phase transition behavior; with raising the temperature it changed as crystal A→liquid→crystal B→liquid. It was found on the basis of the solid 13CNMR spectra that this behavior is ascribed to a conformational change from “cone” (crystal A) to “partial cone” (crystal B).