bluuebunny/crossref_metadata_2025_split huggingface dataset:
Classical Dynamics of the Hydrogen Atom and Muonium Trapped in Diamond Clusters: A Direct Ab-initio Dynamics Study
Authors: Tachikawa Hiroto , Shimizu Akira 
Published: November 2004

Abstract
Direct ab-initio dynamics calculations have been carried out for hydrogen and muonium (Mu) trapped in a C10H16 cluster model in order to elucidate qualitatively the finite temperature effect on f-value ( = |ΦH(0)|2/|Φvac(0)|2, where |Φvac(0)|2 is the contact spin density on H nuclei in vacuum and |ΦH(0)|2 is one in the model cluster). In the dynamics calculations, a split-valence type basis set (31G) was used for the central hydrogen atom and a minimal basis set STO-3G for the cluster model. All atoms were treated as classical particles moving on the ab-initio full dimensional surface including all degrees of freedom calculated at the Hartree–Fock level. Three temperatures, 300, 600, and 1000 K, are chosen as simulation temperatures. The averaged f-values are obtained for each temperature by using MP2/3-21G* level. In addition, the f-value corresponding to 0 K is calculated by the static ab-initio MO calculation (i.e., without dynamics effect). The f-values for 0, 300, 600, and 1000 K were calculated to be 1.224, 1.211, 1.200, and 1.185, respectively, indicating that the f-value linearly decreases with increasing temperature. The f-value was simply expressed by the equation f (T) = f(T = 0 K)[1−0.325 × 10−5 T]. The present calculations indicated that the f-value is slightly affected by the thermal activation, the shift of f-value is small. This work is the first attempt to calculate the finite-temperature effect on the f-value at the ab-initio dynamics level.
Enhanced Formation of Ozone by the Addition of Chloropicrin (Trichloronitromethane) to Propene/NO/Air/Photoirradiation Systems
Authors: Hatakeyama Shiro , Imamura Takashi , Washida Nobuaki 
Published: November 2004

Abstract
The photolysis of chloropicrin in air at 1 atm was performed in a 6-m3 photochemical reaction chamber with a combination of Xe arc lamps and Pyrex filters as a light source. Phosgene was obtained as one of the main products with a yield of unity. No nitrosyl chloride was observed, which supports the C–N scission mechanism for the photolysis. Photochemical ozone formation was enhanced when chloropicrin was added to the propene/NO/air/photoirradiation system after the ozone concentration maximum had been reached. The ozone-formation factor for chloropicrin under the conditions employed was, however, estimated to be 0.25 mole of ozone formed per mole of the decomposed chloropicrin. This implies that the Cl atom, itself, contributes to the destruction of ozone rather than to the formation of ozone under the experimental conditions. NO2 released from chloropicrin is the source of enhanced ozone. If the amount of chloropicrin as a soil fumigant increases, it can cause an increase of the ozone concentration in suburban and/or rural areas.
Assembly of Methylene Blue on Nucleic Acid Template as Studied by Resonance Light-Scattering Technique and Determination of Nucleic Acids of Nanogram
Authors: Huang Cheng Zhi , Li Yuan Fang , Deng Shi You , Liu Shu Rong 
Published: November 2004

Abstract
The template role of nucleic acids in the long-range assembly of Methylene Blue (MB) was characterized with Resonance Light-Scattering (RLS) measurements, and a determination method of nucleic acids of nanogram was proposed. At the pH range 6.87—8.74 and ionic strength lower than 0.01, the interactions of MB with nucleic acids result in two characteristic RLS peaks at 355.0 and 560.0 nm. Mechanism studies show that these peaks result from the long-range assembly of MB on the molecular surface of nucleic acids. A Scatchard plot was constructed by using the RLS data, yielding an assembly number and assembly constant of 5.67 and 9.22 × 104 mol−1 dm3 for MB assembly on the molecular surface of calf thymus DNA (ctDNA), 5.79 and 4.68 × 104 mol−1 dm3 for MB assembly on that of fish sperm DNA (fsDNA). This assembly could be used for analytical purposes and 0—1.4 μg ml−1 for ctDNA, 0—1.2 μg ml−1 for fsDNA, and 0—0.24 μg ml−1 for yeast RNA could be determined if 3.0 × 10−5 mol dm−3 MB was employed. The limits of determination were 11.0 ng ml−1 for ctDNA, 4.9 ng ml−1 for fsDNA and 8.6 ng ml−1 for yeast RNA, respectively. Four synthetic samples were determined with satisfaction.
The Structure of a Meso-Type Heteropolyion of Tetrahydrogen Disodium Dodecamolybdohexaphosphonate(III) (6−) Contained in [NEt4]6[H4Na2(PH)6Mo12O54]·4H2O
Authors: Hori Toshitaka , Taniguchi Nobuko , Himeno Sadayuki , Sano Ken-ichi , Tamada Osamu 
Published: November 2004

Abstract
The structure of [NEt4]6[H4Na2(PH)6Mo12O54]·4H2O (1) has been determined by the single-crystal X-ray method. The crystals are monoclinic, space group of C2/c, with cell parameters a = 23.790(3), b = 16.319(2), c = 28.788(3) Å, β = 114.365(7)°, and Z = 4. The structure model was refined by full-matrix least squares to R = 0.0624 and Rw = 0.0661 for 6798 independent reflections with Fo &gt; 3σ(F) and in 2θ &lt; 50°. The existence of a meso-type heteropolyion [H4Na2(PH)6Mo12O54]6− (2) in the title crystals has been confirmed. It is composed of a pair of enantiomeric moieties of [H2Na(PH)3Mo6O27]3− (3 and 3i, respectively) which are linked by sharing Na+ ions; here, the superscript i denotes the symmetrical operation code of (1/2−x, 1/2−y, −z). The six MoO6-octahedra contained in the respective moieties are arranged to form Plus- and Minus-helices.
Evaluation of the Stability Constants for Alkaline-Earth Metal Complexes with Dodecaoxohexaphosphate(III) Using EDTA as a Complexation-Competing Agent
Authors: Nakashima Toshio , Waki Hirohiko , Tanaka Taichi , Sugihara Gohsuke 
Published: November 2004

Abstract
The stability constants for complexes of a ring oxoanion of phosphorus dodecaoxohexaphosphate(III), with magnesium, calcium, and strontium were evaluated in aqueous solutions at an ionic strength of 0.1. A new spectroscopic equilibrium analysis for a system involving complexes of very high stability was accomplished by introducing EDTA as a complexation-competing agent to the system. The logarithmic stability constant values for the magnesium, calcium, and strontium complexes were found to be 8.4, 8.8, and 7.5, respectively, whose stability order was different from that of a simple one expected from their ionic radii.
Schiff-Base Complexes of Metal(II) as New Catalysts in the High-Regioselective Conversion of Epoxides to Halo Alcohols by Means of Elemental Halogen
Authors: Sharghi Hashem , Naeimi Hossein 
Published: November 2004

Abstract
The ring opening of epoxides with elemental iodine and bromine in the presence of some Schiff-base complexes of the first-row transition metal(II) as new catalysts affords vicinal iodo alcohols and bromo alcohols in high yields. This new procedure occurs regioselectively under mild conditions in various aprotic solvents. The catalysts are easily recovered and can be reused several times.
Cyclodextrin Complexes of Bisepoxide and of α,ω-Diamine in Several Molar Ratios. Preparation and Characterization in the Solid State
Authors: Yamaguchi Isao , Ishii Hidetake , Osakada Kohtaro , Yamamoto Takakazu , Fukuzawa Shin-ichi 
Published: November 2004

Abstract
Addition of 1,4-butanediol diglycidyl ether (glycidyl = 2,3-epoxypropyl) to aqueous solutions of α-cyclodextrin (CD) leads to separation of the 2 : 1 complex from the solution. The 13C CP/MAS NMR spectrum of the complex indicates the presence of diastereomeric oxirane groups formed via the complexation. 1,4-Butanediol diglycidyl ether forms the 1 : 1 or 2 : 2 complex with γ-CD similarly from the aqueous reactions of the two compounds. 2,2-Dimethyltrimethylene glycol diglycidyl ether also forms water-insoluble host–guest complexes with α-CD (2 : 1) and with γ-CD (1 : 1 or 2 : 2). Poly(propylene glycol diglycidyl ether) with an Mn of 640 reacts with β-CD to give the 1 : 4 complex. Poly(tetrahydrofuran) terminated with NH2 groups at both ends also forms the 1 : 4 complexes both with α-CD and with γ-CD.
Sequence-Specific Hybridization between Two Different Types of Peptide Nucleic Acids
Authors: Kuwahara Masayasu , Arimitsu Miki , Sisido Masahiko 
Published: November 2004

Abstract
Nielsen’s-type peptide nucleic acids (PNA) and the oxy-PNA (OPNA), both carrying thymine or adenine bases, were prepared. Hybridizations were observed not only between the complementary pairs of PNA(A12)–DNA(T12) and OPNA(A12)–DNA(T12), but also between the complementary pairs of the artificial nucleic acid analogues, OPNA(A12)–PNA(T12). In the three-component mixture of PNA(T12)–DNA(T12)–OPNA(A12), OPNA(A12) was found to hybridize preferentially with DNA(T12). Addition of DNA(T12) to a preformed duplex of OPNA(A12)–PNA(T12) gave rise to a strand displacement to form a OPNA(A12)–DNA(T12) duplex. No triplex formation was detected in the three-component mixture.
Total Synthesis of a Macrocyclic Antibiotic, Micrococcin P
Authors: Okumura Kazuo , Nakamura Yutaka , Shin Chung-gi 
Published: November 2004

Abstract
The first total synthesis of a macrocyclic antibiotic, micrococcin P (1), was accomplished. After constructing the central 2,3,6-tristhiazolyl-substituted pyridine skeleton [Fragment A—C segment] (21) from ethyl 2-(2-bromoacetyl-6-dimethoxymethyl-3-pyridyl)thiazole-4-carboxylate (15) in 11 steps, successive fragment condensations of 21 with ethyl 2-[(Z)-1-(O-t-butyldiphenylsilyl-l-threonylamino)-1-propenyl]thiazole-4-carboxylate (29) and (S)-1-(O-methoxymethyl-l-threonylamino)-2-(O-methoxymethyl)-2-propanol (25) [the protected Fragments B and D moieties, respectively] gave the protected Fragment A–B–C–D segment 34. Subsequent deprotection of all the protecting groups of 34 with trifluoroacetic acid and then cyclization by using BOP as condensing agent under high dilution conditions gave the expected micrococcin P (1). The synthetic 1 was identical with the natural 1 with respect to the chemical and physical properties.
Highly Efficient Photoinduced DNA Cleavage by Naphthopyrone Hydroperoxides
Authors: Tao Zhi-Fu , Qian Xuhong , Fan Mingcai 
Published: November 2004

Abstract
A variety of naphthopyrone hydroperoxides as novel photochemical DNA cleavers were synthesized and evaluated. Their photochemical DNA-cleaving abilities depend on skeleton arrangement of the naphthopyrone core and are much more efficient than those of the reported 1,8-naphthalenedicarboximide analog. The DNA-cleaving mechanism by these new hydroperoxides probably mainly involves hydroxyl radicals, indicating that naphthopyrone hydroperoxides may be able to serve as a new class of intercalating photo-Fenton reagents.
Significance of the 72-Membered Macrocyclic Structure Found in Archaeal Membrane Lipids: Model Studies of the Macrocyclic Tetraether Diphospholipids by Calorimetric, 31P NMR, and Electron Microscopic Analyses
Authors: Arakawa Kenji , Kano Hiroki , Eguchi Tadashi , Nishiyama Yayoi , Kakinuma Katsumi 
Published: November 2004

Abstract
Described in this paper are the characterizations of the synthetic 72-membered macrocyclic tetraether phospholipids (7, 8) and their acyclic congeners (9, 10), the hydrocarbon chains of which are unbranched straight chains instead of isoprenoid chains such as found in those of archaea. Thermal analyses by differential scanning calorimetry (DSC) clearly showed that the phase transition temperature (Tc) of the cyclic tetraether lipids 7 and 8 was rather lower than those of the corresponding acyclic counterparts 9 and 10. This trend was opposite to that of the diether lipids. The findings from 31P NMR and electron microscopic analyses suggested that the lipid polymorphism of 7 and 8 was quite different from that of 9 and 10. These results revealed that the cyclic structure in 7 and 8 contributed not only to the limitation of motional freedom at the hydrophobic region but also to the change of the lipid polymorphism in comparison with 9 and 10. Furthermore, it was found that these physicochemical as well as polymorphic properties were indistinguishable between the regioisomers 7 and 8 (or 9 and 10).
Proto- and Iodo-lactonization Reaction of Substituted α,β : γ,δ-Unsaturated Carboxylic Acid
Authors: Kuroda Chiaki , Tang Chen Ying , Tanabe Makoto , Funakoshi Masabumi 
Published: November 2004

Abstract
Iodolactonization of 4,5-disubstituted 2-(trimethylsilylmethyl)- and 2-methyl-penta-2,4-dienoic acids was studied. The latter afforded the corresponding iodolactone in good yield by treatment with I2 in MeCN. Iodolactone was also obtained by treatment with I2/NaHCO3/CHCl3/H2O in the presence of cerium(IV) salt as an additive. It was found that protolactonization proceeds by the aid of the trimethylsilyl group, while it prevents iodolactonization.
Thiocrown Ether Additive Effects on Diastereoselectivity of the Lipase-Catalyzed Reaction: Preparation of Optically Active 3-Hydroxy-2-methylalkanenitriles through a Double Enzymatic Reaction Strategy
Authors: Mitsukura Koichi , Choraku Hiroko , Da San Thi , Itoh Toshiyuki 
Published: November 2004

Abstract
The additive effect on diastereoselectivity towards the lipase-catalyzed hydrolysis of acetates of 3-hydroxy-2-methyl- or 3-hydroxy-2-ethylalkanenitriles has been investigated. Diastereoselectivity was not influenced by thiocrown ether additives, although a significant modification of enantioselectivity was observed. Origin of the diastereoselectivity of the lipase-catalyzed reaction was thus evidently different from that of enantioselectivity. Based on these results, an easy preparation of optically active 3-hydroxy-2-methylpentanenitrile and 3-hydroxy-2-methylbutanenitrile have been demonstrated through lipase-catalyzed reaction by a double enzymatic reaction strategy.
Neighboring Group Participation by Heteroaromatic Rings: The Wagner–Meerwein Type Skeletal Rearrangement in the Electrophilic Addition Reactions of Norbornadiene-Fused Furans, Pyrroles, and Thiophenes
Authors: Kobayashi Tomoshige , Tsuzuki Takeo , Saitoh Mayu 
Published: November 2004

Abstract
The electrophilic addition reactions of norbornadiene-fused furans, pyrroles, and thiophenes with bromine, arenesulfenyl chlorides, or a triazoledione generally afforded skeletally rearranged adducts except for a dibenzoyl-substituted thiophene. The formations of the adducts are attributable to the neighboring group participation by five-membered heteroaromatic rings, accompanied by the formations of bridged heteroarenium ions and the subsequent Wagner–Meewein type skeletal rearrangement.
Effect of a Catalyst on the Formation of SiC Whiskers from Polycarbosilane. Nickel Ferrite as a Catalyst
Authors: Otoishi Shinji , Tange Yoshihiro 
Published: November 2004

Abstract
The effect of a catalyst, nickel ferrite, on the formation of SiC whiskers from porous bodies containing polycarbosilane and milled carbon fibers was studied. SiC whiskers were deposited at above 1373 K from porous bodies having a catalyst, while noodle-like SiC products were obtained at above 1473 K from porous bodies having no catalyst. A scanning electron-microscopic analysis and an energy-dispersive X-ray analysis revealed that SiC whiskers were formed via a vapor–liquid–solid process. An X-ray diffraction measurement revealed that the whiskers consisted of β-SiC, and that their crystallinity was significantly high in spite of the heating temperature (1373 to 1623 K). Based on changes in the infrared absorption spectra and gas-evolution curves during the heating process, it was presumed that the pyrolyzing process of polycarbosilane in the two kinds of porous bodies, one with a catalyst, and the other without a catalyst, remarkably resembled each other. SiC whiskers were proved to grow remarkably with decreasing the Si–O bondings by infrared spectroscopy and a chemical analysis. It could therefore be presumed that the formation mechanism of the SiC whiskers was analogous to that of silica–carbothermal reduction.
Effects of Mordenite Support on Photodegradation of Gaseous Organic Compounds over TiO2 Photocatalyst
Authors: Takeda Norihiko , Torimoto Tsukasa , Yoneyama Hiroshi 
Published: November 2004

Abstract
Effects of mordenite as a support material for TiO2 on photodegradation rates of gaseous propionaldehyde, acetone, and propane were investigated using TiO2 (50 wt%)-loaded mordenite as a photocatalyst in reference to unsupported TiO2. The supported photocatalyst allowed adsorption of all the substrates several times greater than the unsupported photocatalyst, resulting in higher photooxidation rates for them. Detailed analysis suggests that the enhancement of the decomposition rate caused by the use of mordenite support is more remarkable for lower amounts of adsorption of the substrates on the support. The concentration of oxygen was found to have little influence on the photodegradation rates, suggesting that the rate of degradation of the organic substrates was not decided by photogenerated electron transfer processes but by the consumption of photogenerated holes by adsorbed organic substrates.
Photochromic Reactions of Two Azobenzene Chromophores in a Chiral Cyclohexane Moiety
Authors: Yamaguchi Tadatsugu , Nakazumi Hiroyuki , Irie Masahiro 
Published: November 2004

Abstract
A chiral cyclohexane containing two photochromic azobenzene units, (1R,2R)-N,N′-bis[4-(phenylazo)benzylidene]-1,2-cyclohexanediamine, was synthesized in an attempt to construct a molecule which shows a large optical rotation change due to photoirradiation. The CD spectrum dramatically changed depending on the configuration of the two azobenzene units. The specific rotations of (E,E)-, (E,Z)- and (Z,Z)-isomers were −1400°, −940°, and −670°, respectivly, while that of the monosubstituted chiral cyclohexane, (1R, 2R)-N-[(4-phenylazo)benzylidene]-N′-benzylidene-1,2-cyclohexanediamine ((E)-isomer), was only −470°. There was no difference in the photoisomerization rates of the azobenzene chromophores attached to chiral and nonchiral cyclohexanes.
Liquid-Crystalline Properties of Dissymmetric Molecules Part 3: Smectic Properties of 4-[2-(Perfluoroalkyl)ethoxy]-Substituted Nitrobenzenes and Benzonitriles
Authors: Duan Meili , Okamoto Hiroaki , Petrov Vladimir F , Takenaka Shunsuke 
Published: November 2004

Abstract
This paper describes the thermal properties of some homologs of 4- and 3-[2-(perfluoroalkyl)ethoxy]-substituted nitrobenzenes and benzonitriles. Many of the homologs show notable smectic properties involving smectic A and B phases. The smectic structures were characterized by an X-ray diffraction examination. The smectic A phase has a partially interdigitated bilayer arrangement where the layer spacing is 1.2—1.8 times the calculated molecular length. Interestingly, some homologs show a smectic B phase with a layer spacing of 2 times the calculated molecular length. Both fluorophilic and polar interactions are supposed to play important roles for the molecular arrangements.
Microvoltammetric Study of Electrochemical Hydrogenation of a Surface-Treated Mg2Ni Alloy Single Particle
Authors: Kim Ho-Sung , Nisizawa Matsuhiko , Itoh Takashi , Uchida Isamu 
Published: November 2004

Abstract
The effects of surface treatments on the hydrogen storage properties of a Mg2Ni alloy particle were investigated by the microvoltammetric technique, in which a carbon-filament microelectrode was manipulated to make electrical contact with the particle placed in a KOH aqueous solution. It was found that the hydrogen storage properties of Mg2Ni at room temperature were improved by the surface treatments with a nickel plating solution. The sodium salts (sodium phosphinate and sodium dihydrogen citrate) contained in the nickel plating solution made the alloy form an amorphous-like state, resulting in an improved hydrogen absorption/desorption capacity at room temperature as high as about 150 mA h g−1 from the original value of 17 mA h g−1.
Interaction of Aminopyridines with Metal Hexacyanoferrates(II)
Authors: Alam Tanveer , Kamaluddin  
Published: November 2004

Abstract
Copper(II) and zinc(II) hexacyanoferrates(II) have been found to be effective adsorbents for aminopyridines, such as 2-amino-, 3-amino-, and 4-aminopyridines. The maximum adsorption was found at neutral pH (pH = 7.0). The adsorption trend followed a Langmuir adsorption isotherm. The Langmuir constants, KL and XM, were determined. The overall adsorption trend was found to be in the order 3-amino- &gt; 4-amino- &gt; 2-aminopyridine. Infrared spectral studies of the adsorption adducts indicate that adsorption takes place through an interaction between the adsorbate molecule and the outer divalent metal ion of metal hexacyanoferrates(II). The results of the present study suggest the importance of metal hexacyanoferrates(II) and metal ions in the stabilization of biomolecules from degradation on primitive earth.
High Magnetic Field Effects on the Lifetimes of Radical Pairs Generated by the Photoreduction of Anthraquinone and n-Alkyl Anthraquinone-2-carboxylates in Micellar Solutions
Authors: Fujiwara Yoshihisa , Yoda Kohji , Tomonari Taro , Aoki Takeshi , Akimoto Yukimi , Tanimoto Yoshifumi 
Published: November 2004

Abstract
The magnetic field effects on the lifetimes of radical pairs (RPs) comprising anthrasemiquinone (AQH·) and alkyl radicals generated in Brij35, HDTCl, and SDS micellar solutions of anthraquinone (AQ) and n-alkyl anthraquinone-2-carboxylates (AQ-n) were studied by laser flash photolysis in high magnetic fields up to 13 T. The RP lifetimes of AQ and AQ-n in the three surfactants increased along with increasing the magnetic field from 0 to about 2 T. The RP lifetimes of AQ in Brij35 and HDTCl drastically decreased in a magnetic field from 3 to 13 T, whereas the RP lifetimes of AQ in SDS were almost constant in the same range of the magnetic field. The increase in the three surfactants was explained by spin-lattice relaxation (SLR) modulated by anisotropic hyperfine and electron dipole–dipole interactions. The drastic decrease in Brij35 and HDTCl was interpreted by SLR modulated by an anisotropic Zeeman interaction. The parameters of the anisotropic g-value and the rotational correlation time for an anisotropic Zeeman interaction were obtained. The constant RP lifetimes in SDS at a high magnetic field were interpreted referring to an escape process of AQH· from the micelle core.
Interpretation of ‘π Energy’ and Its Linear Additivity in Polyenes
Authors: Ichikawa Hiroshi , Yoshida Atsushi , Kagawa Hirotaka , Aihara Jun’ichi 
Published: November 2004

Abstract
The kinetic energy of electrons in a one-dimensional box has the property of a linear additivity with respect to the unit length. This property coincides with that of the π electrons of linear polyenes. Both properties lead to an understanding of why the ‘π energy’ or the Hückel energy includes information about the nuclear configuration based on the molecular virial theorem. This article shows that the linear additivity is a property of the kinetic energy of particles that move in a one-dimensional box, and thus assures that the Hückel energy is another expression of the kinetic energy of π electrons. The reason for the coincidence of both methods is interpreted as meaning that they seek the same stationary wave functions. Thus, we may fairly say that the so-called Hückel energy, ‘π energy’, or the empirical π energy is a quantitative quantity of the kinetic energy of π electrons.
If the interpretation that the ‘π energy’ is the kinetic energy of π electrons is adopted, the explanation for a regular hexagon structure of benzene made by Shaik et al. is reversed.