bluuebunny/crossref_metadata_2025 huggingface dataset:
Storage and recovery of elastic potential energy powers ballistic prey capture in toads
Authors: Lappin A. Kristopher , Monroy Jenna A. , Pilarski Jason Q. , Zepnewski Eric D. , Pierotti David J. , Nishikawa Kiisa C.
Published: June 2006

Ballistic tongue projection in toads is a remarkably fast and powerful movement. The goals of this study were to: (1) quantify in vivo power output and activity of the depressor mandibulae muscles that are responsible for ballistic mouth opening, which powers tongue projection; (2) quantify the elastic properties of the depressor mandibulae muscles and their series connective tissues using in situ muscle stimulation and force-lever studies; and (3) develop and test an elastic recoil model, based on the observed elastic properties of the depressor mandibulae muscles and series connective tissues, that accounts for displacement, velocity, acceleration and power output during ballistic mouth opening in toads. The results demonstrate that the depressor mandibulae muscles of toads are active for up to 250 ms prior to mouth opening. During this time, strains of up to 21.4% muscle resting length (ML) develop in the muscles and series connective tissues. At maximum isometric force, series connective tissues develop strains up to 14% ML, and the muscle itself develops strains up to 17.5%ML. When the mouth opens rapidly, the peak instantaneous power output of the depressor mandibulae muscles and series connective tissues can reach 9600 W kg–1. The results suggest that: (1) elastic recoil of muscle itself can contribute significantly to the power of ballistic movements; (2) strain in series elastic elements of the depressor mandibulae muscle is too large to be borne entirely by the cross bridges and the actin–myosin filament lattice; and (3) central nervous control of ballistic tongue projection in toads likely requires the specification of relatively few parameters.
Metabolic organization of freshwater, euryhaline, and marine elasmobranchs: implications for the evolution of energy metabolism in sharks and rays
Authors: Speers-Roesch B. , Ip Y. K. , Ballantyne J. S.
Published: June 2006

To test the hypothesis that the preference for ketone bodies rather than lipids as oxidative fuel in elasmobranchs evolved in response to the appearance of urea-based osmoregulation, we measured total non-esterified fatty acids (NEFA) in plasma as well as maximal activities of enzymes of intermediary metabolism in tissues from marine and freshwater elasmobranchs,including: the river stingray Potamotrygon motoro (<1 mmol l–1 plasma urea); the marine stingray Taeniura lymma, and the marine shark Chiloscyllium punctatum (>300 mmol l–1 plasma urea); and the euryhaline freshwater stingray Himantura signifer, which possesses intermediate levels of urea. H. signifer also were acclimated to half-strength seawater(15‰) for 2 weeks to ascertain the metabolic effects of the higher urea level that results from salinity acclimation. Our results do not support the urea hypothesis. Enzyme activities and plasma NEFA in salinity-challenged H. signifer were largely unchanged from the freshwater controls, and the freshwater elasmobranchs did not show an enhanced capacity for extrahepatic lipid oxidation relative to the marine species. Importantly, and contrary to previous studies, extrahepatic lipid oxidation does occur in elasmobranchs, based on high carnitine palmitoyl transferase (CPT) activities in kidney and rectal gland. Heart CPT in the stingrays was detectable but low,indicating some capacity for lipid oxidation. CPT was undetectable in red muscle, and almost undetectable in heart, from C. punctatum as well as in white muscle from T. lymma. We propose a revised model of tissue-specific lipid oxidation in elasmobranchs, with high levels in liver,kidney and rectal gland, low or undetectable levels in heart, and none in red or white muscle. Plasma NEFA levels were low in all species, as previously noted in elasmobranchs. D-β-hydroxybutyrate dehydrogenase(d-β-HBDH) was high in most tissues confirming the importance of ketone bodies in elasmobranchs. However, very low d-β-HBDH in kidney from T. lymma indicates that interspecific variability in ketone body utilization occurs. A negative relationship was observed across species between liver glutamate dehydrogenase activity and tissue or plasma urea levels, suggesting that glutamate is preferentially deaminated in freshwater elasmobranchs because it does not need to be shunted to urea production as in marine elasmobranchs.
The cost of running uphill: linking organismal and muscle energy use in guinea fowl (Numida meleagris)
Authors: Rubenson Jonas , Henry Havalee T. , Dimoulas Peter M. , Marsh Richard L.
Published: June 2006

Uphill running requires more energy than level running at the same speed,largely due to the additional mechanical work of elevating the body weight. We explored the distribution of energy use among the leg muscles of guinea fowl running on the level and uphill using both organismal energy expenditure(oxygen consumption) and muscle blood flow measurements. We tested each bird under four conditions: (1) rest, (2) a moderate-speed level run at 1.5 m s–1, (3) an incline run at 1.5 m s–1 with a 15% gradient and (4) a fast level run at a speed eliciting the same metabolic rate as did running at a 15% gradient at 1.5 m s–1(2.28–2.39 m s–1). The organismal energy expenditure increased by 30% between the moderate-speed level run and both the fast level run and the incline run, and was matched by a proportional increase in total blood flow to the leg muscles. We found that blood flow increased significantly to nearly all the leg muscles between the moderate-speed level run and the incline run. However, the increase in flow was distributed unevenly across the leg muscles, with just three muscles being responsible for over 50% of the total increase in blood flow during uphill running. Three muscles showed significant increases in blood flow with increased incline but not with an increase in speed. Increasing the volume of active muscle may explain why in a previous study a higher maximal rate of oxygen consumption was measured during uphill running. The majority of the increase in energy expenditure between level and incline running was used in stance-phase muscles. Proximal stance-phase extensor muscles with parallel fibers and short tendons, which have been considered particularly well suited for doing positive work on the center of mass, increased their mass-specific energy use during uphill running significantly more than pinnate stance-phase muscles. This finding provides some evidence for a division of labor among muscles used for mechanical work production based on their muscle–tendon architecture. Nevertheless, 33% of the total increase in energy use (40% of the increase in stance-phase energy use) during uphill running was provided by pinnate stance-phase muscles. Swing-phase muscles also increase their energy expenditure during uphill running, although to a lesser extent than that required by running faster on the level. These results suggest that neither muscle–tendon nor musculoskeletal architecture appear to greatly restrict the ability of muscles to do work during locomotor tasks such as uphill running, and that the added energy cost of running uphill is not solely due to lifting the body center of mass.
Formation and Optical Absorption Spectra of Mixed Valence State of Tl in Tl2Nb2O6+x with Pyrochlore Structure
Authors: Mizoguchi Hiroshi , Kawazoe Hiroshi , Ueda Takahiro , Hayashi Shigenobu , Hosono Hideo , Ueda Naoyuki
Published: June 2006

The new thallium mixed valence compound Tl2Nb2O6+x (0.1 < x < 1.1) with a defect pyrochlore structure was synthesized by inserting excess oxygen under an oxygen atmosphere up to 2 MPa. A distinct red shift with ca. 0.25 eV of absorption edge was observed on going from x = 0.1 to x = 1.1, and a new and weak absorption band was observed for the samples with large x, at 0.6 eV for x = 1.1 and at 0.8 eV for x = 0.9. The induced band was tentatively ascribed to be due to intervalence charge transfer between Tl+ and Tl3+. As x increased, full width at half maximum of Tl4f7/2 increased from 2.4 to 3.0 eV in X-ray photoemission spectra. 205Tl NMR spectra showed the unusual behavior that the absorption due to Tl+ vanished as x increased to ca. 1. Electrical conducting properties of these compounds were semiconductive, independent of x. The optical and electrical properties demonstrated the presence of the mixed valence states of Tl in these oxides.
Photochemical Behavior of 1,3-Diaryltriazene 1-Oxides
Authors: El-Din Ahmed Moukhtar Nour , Mohamed Shaaban Kamel , Döpp Dietrich
Published: June 2006

Photolysis of the 1,3-dipolar unsymmetrical 1,3-triazene 1-oxides in aromatic and nonaromatic solvents led to their decomposition. 2-Hydroxyazobenzene, mono- and disubstituted biaryls were produced.
Metal Ion-Exchanged Montmorillonites as Practical and Useful Solid Catalysts for the Synthesis of α-Tocopherol
Authors: Matsui Makoto , Yamamoto Hisashi
Published: June 2006

Metal ion-exchanged montmorillonites were found to be efficient catalysts for the condensation reaction of trimethylhydroquinone with isophytol to afford α-tocopherol in high yield. The condensation reaction proceeded smoothly using 50 w/w% of catalyst in various solvents. The catalyst was easily recovered by filtration of the reaction mixture after the reaction was completed, and could be reused.
Mass-Spectrometric Study on Ion–Molecule Reactions of CF3+ with Monosubstituted Benzenes Carrying a Hydroxy or Alkoxy Group at Near-Thermal Energies
Authors: Tsuji Masaharu , Aizawa Masato , Nishimura Yukio
Published: June 2006

The gas-phase ion-molecule reactions of CF3+ with monosubstituted benzenes carrying a hydroxy or alkoxy group [PhX: X = OH, CH2OH, CH2CH2OH, CH(OH)CH3, OCH3, and OC2H5] have been studied at near-thermal energies using an ion-beam apparatus. The major product channels are electrophilic addition on the O-atom, followed by loss of CF3OH, for ROH (R = Ph, PhCH2, PhCH2CH2, PhCHCH3); while they are electrophilic addition to a ring and a substituent, followed by molecular eliminations such as HF, C2H4, and PhF, for PhOCH3 and PhOC2H5. As a minor product channel, charge transfer is found for PhOH, PhOCH3, and PhOC2H5. The reaction mechanism is discussed based on product ion distributions and theoretical calculations of the potential energies of reaction pathways.
Stereochemistry and Some Kinetic Aspects of Fluorination of Phenyl-Substituted Alkenes with SelectfluorTM Reagent F-TEDA-BF4
Authors: Stavber Stojan , Sotler-Pecan Tjaša , Zupan Marko
Published: June 2006

Reactions of phenyl-substituted alkenes with SelectfluorTM fluorinating reagent F-TEDA-BF4 in the presence of various alcohols resulted in the formation of vicinal fluoroalkoxy adducts with Markovnikov type of regioselectivity. The stereochemistry of the fluoro-methoxylation addition reaction was found to be slightly syn predominant in the case of (Z)-stilbene, indene, and dibenzosuberenone, while equal amounts of both diastereoisomers were formed in the case of (E)-1-phenyl-1-propene and acenaphthylene. In the phenyl-substituted benzocyclene series the stereochemistry of fluoro-alkoxylation was found to be dependent on ring size and on the structure of the alcohol. The resulting vicinal fluoroalkoxy adducts were transformed by heating in aqueous HBr to 2-fluoro-1-phenylbenzocyclenes. Correlation of the logarithms of relative rates of fluoro-methoxylation reactions in a series of ten α-phenyl and α,α-diphenyl acyclic and cyclic alkenes with the ionization potentials of these alkenes resulted in a linear relationship with a slope of −2.75. Correlation of log krel for the present reaction with those for the reaction of the same alkenes with CsSO4F or XeF2 yielded excellent linearity for the pair F-TEDA/CsSO4F and scarcely good one for the pair F-TEDA/XeF2. The Hammett correlation analysis of the reaction of substituted 1,1-diphenylethenes with F-TEDA in MeCN/MeOH solvent gave the reaction constant ρ+ of −1.42, so indicating a moderate electron deficiency on the reactive center in the rate-determining step of the reaction.
An Anion Receptor Based on Poly-Substituted Cobalticinium Complexes
Authors: Komatsuzaki Nobuko , Uno Mitsunari , Shirai Kazuhiko , Takai Yoshio , Tanaka Takanori , Sawada Masami , Takahashi Shigetoshi
Published: June 2006

Various derivatives of poly-substituted cobalticinium complexes have been synthesized by using substituted cyclopentadienes with a convertible carboxylic group. By 1H NMR titration experiments, these complexes were shown to behave as a receptor for anions such as Cl−, Br−, AcO−, and p-TsO−. Planar-chiral anilide derivative 3a showed chiral recognition toward camphor-10-sulfonate though the difference of the association constants was 10%. The molecular structure including the absolute configuration of 3a have been established by an X-ray crystallographic analysis. The results suggest the hydrophobic cavity constructed by the substituents on the cyclopentadienyl ligands may be an important component for the successful anion complexation.
Reactivities of Stable Rotamers XXXVII : Thermolyses and Photolyses of 2(1H)-Thioxo-1-pyridyl 3-(1,4-Dimethyl-9-triptycyl)-3-methylbutanoate Rotamers
Authors: Toyota Shinji , Oki Michinori
Published: June 2006

By decomposition of the title compounds, 2-(1,4-dimethyl-9-triptycyl)-2-methylpropyl radical rotamers were generated. In thermolysis the ap-isomer gave, as a main product, a cyclic compound which was formed by attack of the radical on the benzene ring in proximity, whereas extensive rearrangement took place to produce 1-substituted methyl derivatives in the case of sc. In photolysis, various out-of-cage products were found from both rotamers including dimers of radicals. The results are attributed to formation of high concentration of the radicals in photolyses. The product distributions are also affected by the phase, i. e. solution, melts, or solid, as well as temperature. Solid state photolyses afforded 2-pyridyl thioethers as almost exclusive products, suggesting that recombination of radicals in the cage is important under the conditions where movement of the radicals is restricted.
Lipase-Catalyzed Practical Synthesis of (R)-1-Benzyl-3-hydroxy-2,5-pyrrolidinedione and Its Related Compounds
Authors: Tomori Hiroshi , Shibutani Kuniko , Ogura Katsuyuki
Published: June 2006

A practical method for preparing (R)-1-benzyl-3-hydroxy-2,5-pyrrolidinedione (1) was investigated by the use of the enzymatic hydrolysis of its acetate (2a). Among several hydrolases examined here, lipase PS from Pseudomonas cepaciagave the best result: In a mixed solvent (1 : 1 v/v) of dioxane and a phosphate buffer (pH 7), the hydrolysis took place smoothly with a high enantioselectivity (E > 3000). Several 3-alkanoyl derivatives of 1 were subjected to the lipase PS-catalyzed hydrolysis. The chain length of the alkanoyl does not noticeably influence the reaction rate or the enantioselectivity. In contrast, the hydrolysis of the 1-benzoyl derivative proceeded slowly with a low enantioselectivity (E = 19). The syntheses of optically active 3-hydroxypyrrolidines and 3-hydroxypiperidines were also achieved under the reaction conditions similar to the lipase PS-catalyzed hydrolysis of 2a.
Synthesis of 10-Cyanoverticillene and Its Reactions Directed toward the Verticillol Synthesis
Authors: Kato Tadahiro , Hirano Takumi , Hoshikawa Masahiro , Uyehara Tadao
Published: June 2006

Directed toward the synthesis of verticillols, 10-cyanoverticillene 8 was settled as a key intermediate. Bond formation of cyano chloride 7 possessing secoverticillane skeleton to the key intermediate 8 with LiN(TMS)2 at 60 °C proceeded smoothly with moderate yield. The tetrasubstituted double bond of 8 was selectively oxidized, providing the epoxyverticillene derivatives 15 and 16. Hydride reduction of the epoxides were attempted, giving unexpected results. Synthesis of dl-verticillene 13 was also presented.
Oxidative Coupling of Methane on MgO–MgSO4 Catalysts in the Presence and Absence of Carbon Tetrachloride
Authors: Sugiyama Shigeru , Miyamoto Takashi , Hayashi Hiromu , Moffat John B
Published: June 2006

The effect of carbon tetrachloride (CCl4) on the oxidative coupling of methane on binary catalysts containing MgO and MgSO4 was studied at 1048 K. With no CCl4 in the feedstream the conversion of methane increased with increasing content of MgO in the binary catalyst, but was even further enhanced by introducing a small partial pressure of CCl4. The selectivity to ethylene increased upon the addition of CCl4, but was not dependent on either the concentration of CCl4 in the feedstream or the relative amounts of the two components in the catalyst. X-Ray photoelectron spectroscopic analyses of the used catalysts showed that the sulfate is partially transformed into the oxide as well as the formation of Cl species in the near-surface region of the catalysts during the methane conversion process. The addition of CCl4 enhances the conversion of sulfate to oxide. The oxide formed by the decomposition of the sulfate and the chlorine species plays different roles in improving the catalytic activities by introducing CCl4.
Formation of Methanol by Microwave-Plasma Reduction of CO2 with H2O
Authors: Ihara Tatsuhiko , Ouro Takashi , Ochiai Tomoyuki , Kiboku Mitsuo , Iriyama Yu
Published: June 2006

Reduction of CO2 with H2O was carried out by microwave plasma for the formation of methanol. The results of steam chromatography and mass spectrometry showed that the plasma products contained methanol. The methanol formation was also found in H2O-plasma-cleaning process, in which materials which had been deposited in the reaction between CO2 and H2O were removed. The most adequate plasma energy density for the formation of methanol was found to be 0.26 GJ kg−1 of W/FM. The methanol yield at the system pressure of 400 Pa was 3.5 times higher than at 240 Pa for both the CO2–H2O synthetic process and the H2O-cleaning process.
Photophysical Properties and Photosubstitution and Photoredox Reactions of Aromatic Nitro Compounds
Authors: Nakagaki Ryoichi , Mutai Kiyoshi
Published: June 2006

Orientation rules for photochemical nucleophilic substitutions are deduced from intramolecular photoreactions of some bichromophoric chain molecules, p-O2NC6H4O(CH2)nNHC6H5. The lower homologues undergo photochemical nucleophilic substitutions which can be classified as a Smiles-type photorearrangement. The photochemistry of this type of bifunctional chain species depends upon the methylene chain length. When the chain length is sufficiently long, the photorearrangement is totally forbidden. Photoredox reactions are the only accessible reaction processes for the higher homologues. The photoredox reaction consisting of cage and escape pathways is modulated by an external magnetic field. The magnetic field effects on the end product distribution are due to changes in the intersystem crossing rate induced by hyperfine interaction within biradical intermediates.
Stereoselective Synthesis of Cyclopropanes via Homoallylic Participation
Authors: Nagasawa Tetsuya , Handa Yasuhiko , Onoguchi Yuka , Suzuki Keisuke
Published: June 2006

A facile method for synthesizing trans-disubstituted cyclopropanes is described. γ,γ-Dimethyl homoallyl alcohols, upon conversion to the corresponding triflate, undergo smooth cyclization to give cyclopropanes in a stereoselective manner (trans) and in a stereospecific manner (inversion of configuration at the chiral center). Various functionalities could be introduced at the α-position of the newly formed cyclopropane ring by treating the cyclization mixture with hetero as well as carbon nucleophiles. Alternatively, treatment of the reaction mixture with triethylamine effects the clean elimination of a triflic acid to give high yields of the cyclopropanes with a 2-propenyl group, which are convertible to the corresponding cyclopropyl methyl ketones by ozonolysis in high yields. Also described is an application of the method to a short-step synthesis of a cyclopropane-containing eicosanoid, related to marine prostanoid biosynthesis.
Increase of van der Waals Attractive Force under Electromagnetic Field
Authors: Kimura Keisaku
Published: June 2006

A formula for the photoincreased van der Waals attractive force is derived, which includes the effects of the frequency of illuminated electromagnetic waves and of the size of particles. The interparticle interaction energy as a function of the frequency of the electromagnetic wave shows a sharp maximum at the resonance frequency. In the small limit of the size, the van der Waals force under on-resonance irradiation conditions approaches that of molecules and in the large limit the force is drastically reduced. The largest interparticle interaction is found at the size of a few tens of nm. This novel effect is found to be typical of nano-systems.
Mass Spectrometric Investigation of the Vapor over the LnCl3–KCl Equimolar Melt (Ln = Nd, Er) at High Temperatures
Authors: Murase Kuniaki , Adachi Gin-ya , Hashimoto Masashi , Kudo Hiroshi
Published: June 2006

Vaporization of the LnCl3–KCl (Ln = Nd and/or Er) equimolar molten mixture was investigated at 1018—1273 K by means of Knudsen effusion mass spectrometry. The vapor species KCl, K2Cl2, NdCl3, and KLnCl4 were found in the vapor over the melt, and their vapor pressures were evaluated for the NdCl3–KCl system. Volatility enhancement of NdCl3 by the formation of the vapor complex KNdCl4 decreases with increase in temperature. A relatively small enthalpy change, −10 ± 21 kJ mol−1, of the isomolecular exchange KNdCl4(g) + KCl(g) = NdCl3(g) + K2Cl2(g) suggests that the structural change of the reaction is not drastic and that the KNdCl4(g) complex has two bridging and two terminal chlorine atoms.
Coordination Asymmetry of a Dinuclear Copper(II) Complex: Synthesis, Structure, and Magnetism
Authors: Kayatani Takayuki , Hayashi Yoshihito , Suzuki Masatatsu , Inomata Katsuhiko , Uehara Akira
Published: June 2006

A dicopper(II) complex with a novel unsymmetric dinucleating ligand, H2L-1, which can provide donor atom, coordination number, and geometric asymmetries at metal centers, [Cu2(L-1)(CH3COO)]ClO4·H2O·0.5NaClO4 (1), was synthesized, where H2L-1 is a racemic 1-bis(2-pyridylmethyl)amino-3-salicylideneaminopropan-2-ol. The ligand is a hybrid one of 1,3-bis[bis(2-pyridylmethyl)amino]propan-2-ol (Htpdp) and 1,3-bis(salicylideneamino)propan-2-ol (H3L-2). Crystal structure of 1 was determined by X-ray crystallography. Complex 1 crystallizes in monoclinic space group C2/c with a = 42.704(8), b = 12.689(6), c = 29.008(9) Å, β = 128.28(1)°, and Z = 16. The crystal structure showed that two stereoisomers (1a and 1b) are present in solid state. This is attributable to the presence of an enantiomeric pair of L-1. Dinuclear cations consist of one square-planar site with a NO3 donor set and one five-coordinate site with a N3O2 donor set, which are linked by an endogenous alkoxide bridge of L-1 and an exogenous acetate bridge. A powdered sample of 1 shows weak antiferromagnetic interaction (2.60 B.M./Cu2 at 300 and 1.81 B.M./Cu2 at 5 K). Cryomagnetic data is analyzed using two exchange coupling constants, J1 = −0.18 cm−1 and J2 = −9.05 cm−1. EHMO calculations revealed that the observed weak antiferromagnetic interaction(s) compared with that found for [Cu2(L-2)(CH3COO)] (3) (J = −85 cm−1) is reasonably interpreted in terms of the energy gap and the nature of HOMO and LUMO. Some other physicochemical properties of the complex are discussed in comparison with those of the parent complexes, [Cu2(tpdp)(CH3COO)]2+ (2) and [Cu2(L-2)(CH3COO)] (3).
Synthesis and Characterization of Dinuclear and Tetranuclear Mixed-Spin Nickel(II) Complexes with 2,6-Bis(salicylideneaminomethyl)-4-methylphenol
Authors: Mikuriya Masahiro , Nakadera Keiichi , Kotera Takanori
Published: June 2006

Dinuclear and tetranuclear nickel(II) complexes with 2,6-bis(salicylideneaminomethyl)-4-methylphenol (H3L), [Ni2(L)(pz)(Hpz)(CH3OH)]·CH3OH (1) and [Ni4(L)2(pz)2(CH3OH)] (2) (Hpz = pyrazole), have been synthesized and characterized by infrared and electronic spectra, and by temperature dependence of magnetic susceptibilities (80—300 K). The molecular structures of 1 and 2 were determined by single-crystal X-ray structure analysis. Complex 1 is a mixed-spin state complex in which one metal center is square planar and the other octahedral. Complex 2 has a zigzag tetranuclear structure, in which two dinuclear units with mixed spin-states are associated by two phenoxo-bridges and one methanol bridge.
Chemoselective Reductive Coupling of Nitroarenes with Magnesium in Methanol via Single Electron Transfer
Authors: Khurana Jitender M , Ray Abhijit
Published: June 2006

A chemoselective reductive coupling of nitroarenes using magnesium in methanol has been reported at ambient temperature. While the cyano, formyl, methoxycarbonyl, methyl, methoxy, phenyl, amino, and chloro groups are unaffected, iodo and bromo groups undergo dehalogenation but in a slower reaction than the coupling of nitro group. The coupling is believed to be proceeding via SET from Mg to nitroarenes.
Preparation of Novel 1,6-Anhydro-β-lactose Derivatives for the Synthesis of N-Acetyllactosamine-Containing Oligosaccharides
Authors: Tsuda Tetsuro , Furuike Tetsuya , Nishimura Shin-Ichiro
Published: June 2006

Versatile intermediates for the syntheses of cell-surface oligosaccharides bearing N-acetyllactosamine units have been prepared from a readily available 1,6-anhydro-β-lactose as a key starting material. Regioselective chemical manipulations of 1,6-anhydro-β-lactose were carried out in a stepwise procedure and gave fully-protected lactosamine derivatives. It was clearly suggested that modification at C-3′ position of the galactose residue and the following introduction of a sterically hindered leaving group at C-2 position of the reducing glucose remarkably accelerated and facilitated further derivatization of this potential disaccharide material. Selective generation of hydroxyl groups at C-3, C-3′, and/or C-6′ positions proceeded smoothly in mild conditions and afforded a series of fully-functionalized disaccharide-acceptors in high yields.
Synthesis and Some Reactions of Molybdenocene Derivatives Coordinated with the Chiral Carboxylato Ligands
Authors: Ito Takashi , Wan Lin-Ming , Minato Makoto
Published: June 2006

Molybdenocene derivatives with some chiral carboxylato ligand of the types, Cp2MoH(OCOR*), Cp2Mo(OCOR*)2, Cp2MoH(OCO-E*-OCO)MoHCp2, [Cp2Mo(OCOR*)]+R*CO2−, are prepared by the reaction of Cp2MoH2 with chiral 2-methylbutanoic acid, mandelic acid, O-acetylmandelic acid, tartaric acid, and O,O′-diacetyltartaric acid in the presence of ketone and are characterized spectroscopically. Enantioselectivity in the reduction of the prochiral ketones using some of these hydridocarboxylato derivatives is examined.
Selective Formation of 2-Hydroxy-3,3-bis(hydroxymethyl)-γ-butyrolactone from Formaldehyde on Hydrotalcite-Type Catalysts
Authors: Mizutani Tadashi , Miki Yasushi , Nakashima Ruka , Fujita Haruo , Ogoshi Hisanobu
Published: June 2006

As a model for prebiotic sugar formation under neutral to acidic conditions, reactions of formaldehyde over hydrotalcite-type catalysts were investigated. Heating an aqueous solution of formaldehyde at 140—200 °C for 12 h over Ni–Fe hydrotalcite-type catalyst afforded 2-hydroxy-3,3-bis(hydroxymethyl)-γ-butyrolactone selectively, a 5.8% yield based on gas–liquid chromatographic analysis. The structure was identified by 1H and 13C NMR and 1H–13C HSQC, HMBC and 13C–13C 2D INADEQUATE NMR experiments.
Reductive α-Substitution of Sulfoxides with Grignard Reagents Promoted by a Magnesium Amide
Authors: Kobayashi Kazuhiro , Yokota Kouichi , Akamatsu Hideki , Morikawa Osamu , Konishi Hisatoshi
Published: June 2006

The reactions of sulfoxides bearing α-hydrogen(s) (RSOCHR1R2: R-alkyl or aryl; R1, R2 = H, alkyl, or aryl) with Grignard reagents (R3MgBr: R3 = Et, Ph, or vinyl) in the presence of the diisopropylaminomagnesium reagent, generated in situ by the treatment of diisopropylamine with the appropriate Grignard reagents in diethyl ether, have resulted in the formation of the corresponding sulfides (RSCR1R2R3) in moderate to good isolated yields.
Preparations of N
α-Fmoc-O-[(Benzyloxy)hydroxyphosphinyl] β-Hydroxy α-Amino Acid Derivatives
Authors: Wakamiya Tateaki , Nishida Takatoshi , Togashi Ryusaku , Saruta Kunio , Yasuoka Jun-ichi , Kusumoto Shoichi
Published: June 2006

N α -Fmoc-O-[(benzyloxy)hydroxyphosphinyl]serine and Nα-Fmoc-O-[(benzyloxy)hydroxyphosphinyl]threonine were prepared in order to be utilized for the synthesis of phosphoserine- or phosphothreonine-containing peptides based on the Fmoc-mode pre-phosphorylation strategy. These derivatives were obtained as crystalline compounds, which are favorable for use as building blocks for an automated peptide synthesis by a solid-phase method.
Activity Stabilization of Ga-MFI Zeolite Catalyst Modified by Chemical Vapor Deposition
Authors: Bhat Yajnavalkya Subray , Das Jagannath , Halgeri Anand Bhimrao
Published: June 2006

The chemical vapor deposition of silica on Ga-MFI zeolite was carried out using tetraethyl orthosilicate. The enhancement in para selectivity during toluene alkylation with the extent of silica deposition was closely monitored. The effect of reaction temperature on the behavior of silica deposited Ga-MFI zeolite was established. A deactivation trend in toluene conversion was observed when the zeolite was employed for alkylation for longer periods. The reasons for catalytic deactivation and stability enhancement by in situ coking are discussed.
A Nuclear Magnetic Relaxation Study of the Dynamics of NO3− and SCN− Ions in Liquid Ammonia
Authors: Gruwel Marco L H
Published: June 2006

A nuclear magnetic relaxation study of the rotational dynamics of nitrate and thiocyanate anions in 1 M solutions of liquid ammonia is presented. For both anions D⊥ was determined and shown to be larger than observed in aqueous solution. The rotational anisotropy of the nitrate ion was found to be temperature dependent (233—303 K). Thiocyanate ion 13C relaxation was found to be dominated by the spin rotation mechanism. The overall dynamics of both ions is shown to be less restricted in liquid ammonia compared to their dynamics in aqueous solutions.
Anomalous Formation of Ion Conducting Polymer-Networks in Polymer Films
Authors: Ohta Takayuki , Sano Shiho
Published: June 2006

An amphiphilic graft-copolymer consisting of ionic segments (quaternary ammonium groups) and aliphatic polyester segments which are compatible with various polymers was synthesized by radical copolymerization of a (methacryloxyethyl)trimethylammonium chloride and a poly(β-methyl-δ-valerolactone) macromer. Polymer blends containing this graft-copolymer showed both low surface resistance and low volume resistivity, due to the network formation of the graft-copolymer in the polymer matrix. Scanning electron microscopy revealed that the graft copolymer forms interconnected granular aggregates, which function as ion-conducting channels.
Adsorption Behavior of Sulfamethoxazole onto an Alumina-Solution Interface
Authors: Bajpai Anil Kumar , Rajpoot Manjulata
Published: June 2006

The adsorption measurements of sulfamethoxazole (SM) onto an alumina surface have been done at room temperature with an object to study the mode of SM adsorption at the solution–alumina interface. It is found that the adsorption isotherm is of the Langmuir type, showing a uni-layer formation of the SM molecules on the alumina surface. The adsorption is pH-dependent and found to increase with increasing pH of the medium. The adsorption is quite sensitive to the presence of Cl− and SO42− ions also and shows much interesting variation with increasing concentrations of the added anions. The adsorption also decreases with increasing temperature of the adsorption medium. Various kinetic and adsorption parameters such as the adsorption coefficient, rate constants for the adsorption and desorption, and surface coverage have been evaluated with the help of a proposed kinetics scheme.
Chemisorption on Metal Surfaces: Cluster Model Studies
Authors: Xu Xin , Wang Nanqin , Zhang Qianer
Published: June 2006

After exploring the underlying physics of the cluster-surface analogy, we propose the concept of “metallic atom”. The importance of employing a metallic cluster in the cluster modeling of chemisorption is illustrated with some case studies.
Experimental Studies of Ozone Depletion by Chlorofluorocarbons (CFC’s), Bromofluorocarbons (BFC’s), Hydrochlorofluorocarbons (HCFC’s), and CH3Br Using a 6-m3 Photochemical Chamber
Authors: Washida Nobuaki , Imamura Takashi , Bandow Hiroshi
Published: June 2006

Ozone destruction by CFC’s (CFCl3 and CF2Cl2), BFC’s (CF3Br and C2F4Br2), HCFC’s (CH3CCl2F, CF3CHCl2, and CF3CHFCl), and CH3Br was demonstrated using a 6-m3 evacuable photochemical chamber equipped with UV-enhanced Xe arc lamps. The decay of ozone by a catalytic cycle involving Cl or Br atoms released from the photolysis of halocarbons by UV light was evident, although the chain length was far less than that in the real stratosphere: It was about 8 for CFCl3 and 40 for CF3Br. The rates of ozone decomposition were faster in the BFC’s than in the CFC’s. According to a box-model simulation, in the CFCl3 system 90% of the catalytic cycle proceeds from reactions of Cl + O3 → ClO + O2 and ClO + O → Cl + O2. On the other hand, in the CF3Br system 90% of the catalytic cycle is governed by the following reactions: Br + O3 → BrO + O2 and BrO + BrO → 2Br + O2. The HCFC’s and CH3Br can destroy the ozone with sufficient potential as CFC’s and BFC’s when they enter the stratosphere.
Infrared Laser-Induced Photo-Thermal Phase Transition of an Aqueous Poly(N-isopropylacrylamide) Solution in the Micrometer Dimension
Authors: Ishikawa Masazumi , Misawa Hiroaki , Kitamura Noboru , Fujisawa Ryo , Masuhara Hiroshi
Published: June 2006

The phase transition of an aqueous poly(N-isopropylacrylamide) solution (PNIPAM, wt% = 1.8—3.6%) was induced by the irradiation of a focused (ca. 1 μm) 1064-nm laser beam; this brought about the formation of a single PNIPAM microparticle. The diameter of the particle was controlled to 2—9 μm through the laser power, polymer concentration, and solution temperature. The primary origin of particle formation was the photo-thermal phase transition of the polymer solution through the local heating of water (H2O) by the laser beam. The characteristic features of the phenomena, including manipulation of the PNIPAM particle by the incident laser beam and the role of radiation force for the particle formation, are discussed.
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

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

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

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

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 > 0.995 and SD < 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

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

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

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 > 5′-ADP > adenine > 5′-AMP > 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

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

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

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.