bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of the Dissolved Structures and Condensation Reactivities of Mononuclear Molybdenum(VI) Species in Solution Using the UV-vis Absorption Spectra and Molecular Orbital Calculation DV-Xα
Authors: Ozeki Toru , Adachi Hirohiko , Ikeda Shigero 
Published: June 2006

Abstract
The dissolved structures of the mononuclear molybdate species, MoO42−, HMoO4−, and H2MoO4, in aqueous solution were estimated by optimizing their structure models so that their UV-vis absorption spectra were well reproduced by the DV-Xα molecular orbital calculation. In this paper it is proposed that the former two species are tetrahedral ions, and the last is a distorted octahedral species. Using the values of the bond order obtained by a Mulliken population analysis the reason why the dimolybdate anion Mo2O72− does not exist, in contrast with the presence of the well-known dichromate anion Cr2O72−, has been explained. The key species which plays an important role in condensation reactions of molybdate system is not the HMoO4− ion, but the H2MoO4 with very weak Mo–OH bonds.
Synthesis, Crystal Structure, and Magnetic Property of a Dinuclear Oxovanadium(IV) Complex with 2,6-Bis(salicylideneaminomethyl)-4-methylphenol
Authors: Mikuriya Masahiro , Fukuya Mika 
Published: June 2006

Abstract
A dinuclear oxovanadium(IV) complex with 2,6-bis(salicylideneaminomethyl)-4-methylphenol (H3L), [(VO)2(L)(CH3O)(dmso)] (1) (dmso = dimethyl sulfoxide), has been synthesized and characterized by infrared and electronic spectra, and by the temperature dependence of magnetic susceptibilities (80—300 K). The molecular structure of 1 was determined by single-crystal X-ray structure analysis. The two octahedral vanadium ions are bridged by a phenoxo-oxygen of L, a methoxo ion, and a dimethyl sulfoxide and have syn oxo configuration. The magnetic property was discussed in relation to the crystal structure.
Near-Threshold Photodissociation of C2H2, C2HD, and C2D2 Studied by H(D) Atom Photofragment Translational Spectroscopy
Authors: Wilson Steven H S , Reed Claire L , Mordaunt David H , Ashfold Michael N R , Kawasaki Masahiro 
Published: June 2006

Abstract
The photodissociation of jet-cooled C2H2, C2HD, and C2D2 molecules following excitation within their respective predissociated absorption band systems has been investigated using the technique of H(D) Rydberg-atom photofragment translational spectroscopy. Analyses of the rotational structure apparent in the resulting total kinetic-energy release spectra yields precise values for the DCC–H, HCC–D, and DCC–D bond dissociation energies: (DCC–H) = 46144 ± 50 cm−1, (HCC–D) = 46687 ± 50 cm−1, and (DCC–D) = 46754 ± 50 cm−1, respectively. The average internal excitation of bending vibration in the C2H(C2D) fragments formed from these photolyses of all three parent isotopomers is shown to scale linearly with the excess energy over and above that required for bond fission by ca. 540 cm−1.
Solvent Effects on Anchimerically Assisted Solvolyses. III. Solvent Effects on the Solvolyses of (1-Arylcycloalkyl)methyl p-Toluenesulfonates
Authors: Fujio Mizue , Saeki Yoshihiro , Nakamoto Kenichiro , Kim Sung Hong , Rappoport Zvi , Tsuno Yuho 
Published: June 2006

Abstract
The solvolysis rates of (1-arylcyclobutyl)methyl and (1-arylcyclopropyl)methyl p-toluenesulfonates were measured in a wide variety of solvents. The aryl-assisted kΔ solvolysis of [1-(p-methoxyphenyl)cyclobutyl]methyl p-toluenesulfonate did not give a linear Winstein–Grunwald correlation using the 2-adamantyl-based YOTs scale, but did show dispersion for different binary solvent mixtures. An extended dual-parameter treatment, log (k/k80E) = mcYOTs + mΔYΔ, successfully correlated the present set of kΔ solvolyses with R &gt; 0.995 and SD &lt; 0.09. The blending parameter MΔ (= 0.51mΔ/(mc + 0.51mΔ)) increases monotonically with increased electron donation by the substituent, showing an increased dispersion of the YOTs plot with increasing anchimeric assistance. The solvolysis of (1-arylcycloalkyl)methyl p-toluenesulfonates demonstrates the varying extent of anchimeric assistance by the neighboring groups, from a completely synchronous aryl-assisted process for the p-methoxy derivative of (1-phenylcyclobutyl)methyl p-toluenesulfonate, via moderately to weakly aryl-assistance by the p-methyl derivative and the unsubstituted compound, to a completely aryl-unassisted kc process for the more electron-withdrawing aryl derivatives and the (1-arylcyclopropyl)methyl p-toluenesulfonates. The dual-parameter equation enables one to monitor the varying extent of anchimeric assistance in the transition state. From the results we propose a general solvolysis framework involving a continuous spectrum of kc − kΔ mechanisms for anchimerically assisted solvolysis.
Photochemical EZ-Isomerization of α,β-Unsaturated Amides and Thioamides in the Solid State
Authors: Kinbara Kazushi , Saigo Kazuhiko 
Published: June 2006

Abstract
The solid-state EZ-isomerizability of α,β-unsaturated amides, which had low isomerizability in the solid state, was greatly improved by modifying their structure; EZ-isomerizability was attained by replacing the carbonyl group of the amides by a thiocarbonyl group as well as replacing the heterochiral N-substituent of the amides by a homochiral one. Crystallographic analyses have revealed that the isomerizability of α,β-unsaturated amides and thioamides in the solid state partially depends on their molecular conformation in crystal. In addition, it was found that the packing coefficient has a correlation with the isomerizability; a smaller value of the packing coefficient caused an increased formation of (Z)-isomers.
Effect of Oxygen on Polypyrrole as Studied by Conductivity and ESR Measurements
Authors: Adachi Akira , Yamauchi Jun 
Published: June 2006

Abstract
The effect of oxygen on polypyrrole (PPy) doped with benzenesulfonate has been investigated by electric conductivity and electron spin resonance (ESR) measurements. There are two regions in the changes of the conductivity, the linewidth and the spin concentration with respect to the pressure of oxygen. When the pressure decreased in the range from ambient pressure to 0.2 Torr (region I), the conductivity increased consistently with the relationship of the Langmuir adsorption, in which we assumed that the amount of adsorption was in proportion to the inverse of conductivity. This effect was reversible with respect to the pressure, indicating physical adsorption in this region I. The oxygen desorption by reducing the pressure caused a rapid decrease of the linewidth as well as the spin concentration. It was concluded that the linewidth variation is due to the reduction of dipole–dipole interactions between the unpaired electrons of the oxygen molecules and radicals of PPy (polarons), while the spin concentration variation is due to the disappearance of the oxygen molecules. Below 0.2 Torr (region II), the conductivity increased, deviating from the Langmuir relationship, while the ESR spectra almost remained constant. These findings were discussed, considering that the interaction positions of the adsorption were radical sites (polarons) in connection with the conductive process and that only a small number of the oxygen molecules adsorbed in this region II.
Adsorption of Adenine, Adenosine, and Adenosine Nucleotides on Nickel(II) Hexacyanoferrate(II)
Authors: Viladkar Sushama , Agarwal Rachana , Kamaluddin  
Published: June 2006

Abstract
Nickel(II) hexacyanoferrate(II) has been found to be an effective adsorbent for number of biomonomers such as adenine, adenosine, 5′-AMP, 5′-ADP, and 5′-ATP. The adsorption is maximum at a pKa value specific to each biomonomer. The specific binding ability of adsorbate is related to the number of phosphate groups attached to an adenosine moiety. The overall adsorption trend is found to be in the order of 5′-ATP &gt; 5′-ADP &gt; adenine &gt; 5′-AMP &gt; adenosine. The infrared spectral studies of adsorption adducts suggested that adsorption takes place due to the complex formation between adsorbate molecule and outer divalent metal ion of nickel(II) hexacyanoferrate(II). Such adsorption processes could have helped in the protection of biomolecules from degradation on the primitive earth.
Dynamic Processes in Electrochemical Reactions Studied by Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS)
Authors: Osawa Masatoshi 
Published: June 2006

Abstract
Molecules adsorbed on evaporated thin metal films exhibit enormously strong infrared absorption. The thin metal films that exhibit the surface-enhanced infrared absorption (SEIRA) consist of metal particles much smaller than the wavelength of light. Electric field associated with the incident infrared radiation is enhanced via the excitation of localized plasmon of the particles, yielding the absorption enhancement. Preferential orientation and the change in absorption coefficient of molecules caused by chemisorption onto the metal surface provide additional enhancement. Most characteristic observations in SEIRA experiments are well explained by a simple electromagnetic theory. The infrared spectroscopy utilizing the SEIRA effect is promising as a new surface analytical tool. In particular, it is very useful for in situ studies of electrode/electrolyte interfaces. By the combined use of the attenuated-total-reflection technique, reactions and adsorption/desorption of molecules at the interfaces can be investigated at a high sensitivity without the interference from the bulk solution. The high sensitivity of this technique enables dynamic (or time-resolved) infrared monitoring of reactions and other time-dependent phenomena at the electrochemical interface at time-resolutions ranging from microseconds to milliseconds. Two-dimensional correlation analysis of time-resolved spectra highlights certain useful information that is not clearly seen in the usual one-dimensional spectra.
Dispersion Stability of Phytoglycogen in Water/Phytoglycogen/Various Nonionic Surfactant Systems: Effect of Hydrophile–Lipophile Balance (HLB) of Nonionic Surfactants
Authors: Nakano Akihiro , Tateishi Koichi 
Published: June 2006

Abstract
The phase behavior was investigated in water/phytoglycogen/water-soluble nonionic surfactant (poly(oxyethylene) type surfactant, CmEOn) systems, showing that phytoglycogen is precipitated by the addition of those surfactants. Therefore, the effect of the hydrophile–lipophile balance (HLB) on the dispersion stability of phytoglycogen (DSP) was assessed.
At constant-temperature, phytoglycogen in a lower HLB surfactant system dispersed more stably than that in a higher HLB surfactant system. With raising the temperature, the DSP in the higher HLB surfactant system was improved, whereas phytoglycogen became to disperse unstably in a low-HLB surfactant (C12EO7) system. In the C12EO9 and C12EO10 systems, the DSP was improved over a range of lower temperatures, whereas phytoglycogen became to disperse unstably over a range of higher temperatures. We proposed a schematic representation on the phase behavior in water/phytoglycogen/nonionic surfactant systems. It was clarified that DSP in phytoglycogen and surfactant-coexisting systems depends on the HLB and the aggregation number of each surfactant. Furthermore, the characteristics of surfactant micelles in water were evaluated macroscopically from the investigation.
Migration of ortho-Positronium in Polymer Films
Authors: Tanaka Kazuhiro , Kawai Toshinao , Kita Hidetoshi , Okamoto Kenichi , Ito Yasuo 
Published: June 2006

Abstract
Positron-annihilation measurements were performed for polymer films containing quenchers of ortho-positronium (o-Ps) in order to obtain information about the migration of o-Ps. The diffusion coefficients of o-Ps, estimated from the quenching-rate constants, were (1—2) × 10−6 cm2 s−1 at 298 K, which lead to root-mean-square distances of 1.5—2.4 nm during its lifetime. o-Ps is considered to migrate through more than several free-space holes until pick-off annihilation, suggesting that the size estimated from the lifetime of o-Ps corresponds to an average size weighted to the larger size because o-Ps is more stable in larger holes. The diffusion coefficients of o-Ps were compared with those of gas molecules, leading us to conclude that the migration of o-Ps follows a different mechanism from that of the diffusion of gas molecules. The quenchers also had the effect of inhibiting o-Ps formation in the polymers, and the inhibition coefficients were determined to be 6—17 M−1, which are as high as the corresponding values in benzene solutions.
Molecular Motions in Highly Disordered Solid Phases of [(CH3)3NCH2CH3]X (X = ClO4, PF6, NO3) Studied by 1H, 19F, and 14N NMR, Powder X-Ray Diffraction, and Differential Scanning Calorimetry
Authors: Ono Hiroshi , Ishimaru Shin’ichi , Ikeda Ryuichi , Ishida Hiroyuki 
Published: June 2006

Abstract
1H, 19F, and 14N NMR, powder X-ray diffraction, and differential scanning calorimetry (DSC) were measured in trimethylethylammonium perchlorate, hexafluorophosphate and nitrate, [(CH3)3NCH2CH3]X (X = ClO4, PF6, NO3). Three, four and four solid phases were obtained for perchlorate, hexafluorophosphate, and nitrate, respectively, in the temperature ranges from 77 K to their decomposition temperatures. X-Ray powder patterns showed that the highest-temperature solid phases of perchlorate and hexafluorophosphate are CsCl-type cubic, while that of nitrate is NaCl-type cubic. The second highest-temperature phases of perchlorate and hexafluorophosphate form tetragonal lattices. The NMR study revealed that the cations perform isotropic rotation as well as self-diffusion in the CsCl-type cubic and tetragonal phases of perchlorate. In the cubic phase of hexafluorophosphate, isotropic rotation and self-diffusion of both anion and cation were observed. In the NaCl-type cubic phase of nitrate, isotropic rotation of both ions was detected. The structures in the highest- and second highest-temperature phases of the three salts were found to be dynamically disordered. Especially, the highest-temperature phases of perchlorate and hexafluorophosphate can be classified into the ionic plastic phase of the CsCl-type structure. Activation energies of the ionic motions in these phases were evaluated. Motional modes of the ions in the lower temperature phases were also deduced.
A New Macrocyclic Ligand-Based Sensor for Nickel(II) Ions
Authors: Singh Ashok Kumar , Bhattacharjee Gurudas , Singh Manendra , Chandra Sudeshna 
Published: June 2006

Abstract
A new 14-membered macrocyclic ligand containing nitrogen donor atoms was prepared and characterized. The macrocycle behaves as a selective chelating ion exchanger for some metal ions. The PVC-based membrane electrode of the macrocycle shows a Nernstian response for nickel(II) ions over a wide concentration range (0.294 to 58.69 × 102 mg dm−3) between pH 3.0 to 7.0. The electrode is found to possess adequate stability and specific selectivity with a response time of 10 s. The sensor can also be used in a partially nonaqueous medium having a 35% (v/v) nonaqueous content. The membrane exhibits excellent selectivity for nickel(II) ions, and no disturbance is observed by normal interferents like Cu2+, Cd2+, Co2+, Pb2+, Zn2+, Mg2+, and Hg2+ ions. The electrode has been successfully used for estimating Ni2+ ions in milk powders, chocolates, and hydrogenated vegetable oils. Small amounts (≤5.0 × 10−5 mol dm−3) of hexadecyltrimethylammonium bromide do not disturb the functioning of the membrane sensor.
Synthesis of Some Crystal Forms of Strontium Sulfite by Metasilicate Gel Method and Crystal Form Control
Authors: Kohiruimaki Takayuki , Matsuda Keizo 
Published: June 2006

Abstract
The purpose of this study is to synthesize strontium sulfite crystals with characteristic forms by a metasilicate gel-growth method and to determine the optimum conditions for synthesis of the crystals. Strontium ions were diffused into metasilicate gel including sulfite ions in order to synthesize strontium sulfite crystals. The crystals were synthesized in the pH range of 4.0 to 11.0, at a diffusion temperature between 5 and 40 °C, in the following concentration ranges: sodium sulfite, 0.2 to 1.5 mol dm−3, and strontium chloride, 0.2 to 3.0 mol dm−3. As a result, strontium sulfite crystals were obtained in the following four forms: spherical, poly-spherical, ellipsoidal, and spindle. The cause of the crystal form change was found to be a difference in the growth side by comparison of X-ray diffraction patterns. In addition, the optimum conditions which controlled the crystal form were influenced by the pH value in the gel and the temperature.
Synthesis and Complexation Behavior of Diaza-18-crown-6 Carrying Two Pyrenylmethyl Groups
Authors: Kubo Kanji , Kato Nobuo , Sakurai Tadamitsu 
Published: June 2006

Abstract
N,N′-Bis(1-pyrenylmethyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (1) and N-(1-pyrenylmethyl)-1,4,7,10,13-pentaoxa-16-azacyclooctadecane (2) were synthesized and found to display unique photophysical properties in the presence of the guest-metal salts. The binding of metal ions to the diazacrown ether 1 cavity inhibited the exciplex formation and changed the distance between two pyrenyl groups. This caused not only an emission-intensity enhancement, but also a large change in the monomer/excimer fluorescence-intensity ratio. The change resulted from the coordinated structure and exchange process between the free host 1 and its metal salt complex in the ground state.
Substituent Effects on the Solvolysis of 2,2,2-Trifluoro-1,1-diphenylethyl Tosylates. II. 3-Chlorophenyl- and 3,5-Dichlorophenyl-Fixed Systems
Authors: Fujio Mizue , Morimoto Hiroshi , Kim Hyun-Joong , Tsuno Yuho 
Published: June 2006

Abstract
The solvolysis rates of 2,2,2-trifluoro-1-(3-chlorophenyl)-1-(substituted phenyl)ethyl and 2,2,2-trifluoro-1-(3,5-dichlorophenyl)-1-(substituted phenyl)ethyl tosylates or bromides were conductimetrically measured at 25.0 °C in 80% aqueous ethanol. The 3-chlorophenyl-fixed series showed a bilinear Yukawa–Tsuno correlation with ρ = −4.81 and r = 1.41 for substituents more deactivating than 3,5-dimethyl, and with ρ = −6.19 and r = 1.57 for the substituent range more activating than 4-methyl. The bilinear correlation was interpreted in terms of the changing coplanarity of the two aryl rings. The 3,5-dichlorophenyl-fixed substrates gave an excellent linear Yukawa–Tsuno correlation for the substituents ranging from 4-MeO to 4-Cl with ρ = −5.95 and r = 1.69. The variable aryl rings in this series show the largest extent of resonance interaction with the extraordinary deactivated carbenium ion center by α-CF3 and α-(3,5-dichlorophenyl) groups in the transition state. The optimization of the geometries of 2,2,2-trifluoro-1,1-diphenylethyl cation and some ring-substituted derivatives was performed at the RHF/6-31G* level. The symmetric diaryl cations have equivalently twisted conformations, while in unsymmetric ones the more stabilizing aryl group is less twisted from the plane of the positive sp2 carbon. The observed variation of r and ρ parameters is accommodated by geometrical changes of the incipient cation.
Syntheses and Crystal Structures of ET and BETS Salts Containing Bis(dithiosquarato)metalate Anions
Authors: Tanaka Hisashi , Kobayashi Akiko , Kobayashi Hayao 
Published: June 2006

Abstract
A series of cation radical salts of bis(ethylenedithio)tetrathiafulvalene (ET) and bis(ethylenedithio)tetraselenafulvalene (BETS) as donors and bis(dithiosquarato)metalate ([M(dts)2]n−) as anions were synthesized. The electrical resistivities of most of these salts ((BETS)2[Pd(dts)2] (1), (BETS)2[Pd(dts)2]·2(1,1,2,2-TCE) (2) (1,1,2,2-TCE = 1,1,2,2-tetrachloroethane), (BETS)[Au(dts)2] (4), (ET)2[Pd(dts)2] (5), (ET)2[Pt(dts)2] (6), and (ET)[Au(dts)2] (7)) were semiconductive. However, one of the BETS salts with [Pd(dts)2], whose donor : anion ratio was 5 : 1. (BETS)x[Pd(dts)2] (x ≈ 5.0) (3), showed a metallic behavior down to 4 K. Although the crystal structure of these semiconducting salts was a kind of mixed stacks, many short contacts within the sum of the van der Waals radii were seen between chalcogens of the donors, and between chalcogens of the donor and anion. In addition, four terminal oxygen atoms of bis(dithiosquarato)metalate anion had C–H···O hydrogen bonds with terminal ethylene groups of ET and BETS, which was one of the factors determining the conformation of the terminal ethylene groups in these crystals.
Perfluoroalkylsulfonyl-Substituted Azobenzenes as Second-Order Nonlinear Optical Chromophores
Authors: Matsui Masaki , Kawase Ritsu , Funabiki Kazumasa , Muramatsu Hiroshige , Shibata Katsuyoshi , Ishigure Yoshinao , Hirota Kazuo , Hosoda Masahiro , Tai Kazuo 
Published: June 2006

Abstract
4-Perfluoroalkylsulfonyl (RfSO2)-substituted azo nonlinear optical chromophores (NLOphores) showed enhanced second-order nonlinear coefficients (d33) and improved relaxation behavior compared with the corresponding nitro compound (Disperse Red 1 (DR 1)) in both doped poly(methylmethacrylate) (PMMA) and pendanted methylmethacrylate (MMA) copolymer.
Liquid-Crystalline Properties of Alkyl 4-[2-(Perfluorooctyl)ethoxy]benzoates
Authors: Okamoto Hiroaki , Murai Hiroshi , Takenaka Shunsuke 
Published: June 2006

Abstract
This paper describes the liquid-crystalline properties of alkyl 4-[2-(perfluorooctyl)ethoxy]benzoates (1) and bromo (2) and nitro (3) substituted compounds. For 1, the lower members show a smectic A phase; also the smectic A-isotropic transition temperatures and the latent heats decrease with increasing the carbon number of the hydrocarbon chain. An X-ray examination indicated that the smectic A phase has an interdigited arrangement of molecules. The results are discussed in terms of inter- and intra-layer fluorophilic interactions around the perfluorooctyl groups.
Frictional Ignition Testing of Composite Materials
Authors: Peralta S , Rosales K , Robinson MJ , Stoltzfus J 
Published: June 2006

Abstract
The space flight community has been investigating lightweight composite materials for use in propellant tanks for both liquid and gaseous oxygen for space flight vehicles. The use of these materials presents some risks pertaining to ignition and burning hazards in the presence of oxygen. Through the hazard analysis process, some ignition mechanisms have been identified as being potentially credible. One of the ignition mechanisms was reciprocal friction; however, test data do not exist that could be used to clear or fail these types of materials as “oxygen compatible” for the reciprocal friction ignition mechanism. Therefore, testing was performed at the NASA Johnson Space Center White Sands Test Facility to provide data to evaluate this ignition mechanism. This paper presents the test system, approach, data results, and findings of the reciprocal friction testing performed on composite sample materials being considered for propellant tanks.
Vertical Mandibular Alveolar Bone Distraction and Dental Implant Placement: A Case Report
Authors: Peñarrocha-Diago Miguel , Gómez-Adrián M. Dolores , García-García Abel , Camacho-Alonso Fabio , Rambla-Ferrer Javier 
Published: June 2006

Abstract
Extensive bone defects complicate the adequate placement of dental implants and the required angulation. In such cases, alveolar-ridge augmentation techniques such as guided bone regeneration, particulate or block grafting, and alveolar bone distraction are needed. The present study describes a case in which a large vertical bone defect in the anterior mandibular zone was corrected via vertical alveolar bone distraction. Six dental implants were posteriorly placed for implant-supported restoration of the mandible, with early implant loading. The clinical and radiologic control showed good implant and soft tissue conditions 12 months later.