bluuebunny/crossref_metadata_2025 huggingface dataset:
Knockdown of the complete Hox paralogous group 1 leads to dramatic hindbrain and neural crest defects
Authors: McNulty Claire L. , Peres João N. , Bardine Nabila , van den Akker Willem M. R. , Durston Antony J.
Published: June 2005

The Hox paralogous group 1 (PG1) genes are the first and initially most anterior Hox genes expressed in the embryo. In Xenopus, the three PG1 genes, Hoxa1, Hoxb1 and Hoxd1, are expressed in a widely overlapping domain, which includes the region of the future hindbrain and its associated neural crest. We used morpholinos to achieve a complete knockdown of PG1 function. When Hoxa1, Hoxb1 and Hoxd1 are knocked down in combination, the hindbrain patterning phenotype is more severe than in the single or double knockdowns, indicating a degree of redundancy for these genes. In the triple PG1 knockdown embryos the hindbrain is reduced and lacks segmentation. The patterning of rhombomeres 2 to 7 is lost, with a concurrent posterior expansion of the rhombomere 1 marker, Gbx2. This effect could be via the downregulation of other Hox genes, as we show that PG1 function is necessary for the hindbrain expression of Hox genes from paralogous groups 2 to 4. Furthermore, in the absence of PG1 function, the cranial neural crest is correctly specified but does not migrate into the pharyngeal arches. Embryos with no active PG1 genes have defects in derivatives of the pharyngeal arches and, most strikingly, the gill cartilages are completely missing. These results show that the complete abrogation of PG1 function in Xenopus has a much wider scope of effect than would be predicted from the single and double PG1 knockouts in other organisms.
From genes to plants via meristems
Authors: Hay Angela , Tsiantis Miltos
Published: June 2005

The Society for Experimental Biology organised a `Plant Frontier' meeting,which was recently held at the University of Sheffield, UK. One of the sessions of this broad meeting was on plant meristems, which covered a range of topics, including stem cells, patterning, long distance signalling and epigenetic regulation of meristem development.
Cdc42 controls the polarity of the actin and microtubule cytoskeletons through two distinct signal transduction pathways
Authors: Cau Julien , Hall Alan
Published: June 2005

Cdc42, a Rho family GTPase, is a key regulator of cell polarity. In Saccharomyces cerevisiae, it is required for polarized bud formation and pheromone gradient sensing, while in higher eukaryotes, it participates in asymmetric cell division, directional sensing during migration, and morphogenesis. Using a scratch-induced fibroblast migration assay, we previously showed that Cdc42 controls the polarization of both membrane protrusions and the Golgi/centrosome. We now find that Golgi/centrosome polarity is mediated through activation of the Par6/aPKC complex, as previously described in astrocytes. However, this complex is not involved in Cdc42-dependent polarization of protrusions, which instead is mediated by Pak acting through the Rac guanine nucleotide exchange factor, βPIX. Pak kinase activity is essential for spatially restricting Rac-dependent actin polymerization to the leading edge of the migrating cells, though it is not required for actin polymerization per se. We conclude that in migrating cells, Cdc42 co-ordinately regulates the polarity of the microtubule and actin cytoskeletons through two distinct pathways.
Overexpression of claudin-7 decreases the paracellular Cl– conductance and increases the paracellular Na+ conductance in LLC-PK1 cells
Authors: Alexandre Michele D. , Lu Qun , Chen Yan-Hua
Published: June 2005

Tight junctions form the primary barrier regulating the diffusion of fluid, electrolytes and macromolecules through the paracellular pathway. Claudins are the major structural and functional components of tight junction strands and are considered as the best candidates for forming paracellular channels. They are a family of integral membrane proteins with more than 20 members and show distinct tissue distribution patterns. In this study, we found that claudin-7 is expressed in the distal and collecting tubules and the thick ascending limb of Henle of porcine and rat kidneys. To investigate the role of claudin-7 in paracellular transport, we have overexpressed a mouse claudin-7 construct in LLC-PK1 cells. Overexpression of claudin-7 did not affect the expression and localization of endogenous claudin-1, -3, -4, -7, and ZO-1. However, transepithelial electrical resistance in claudin-7-overexpressing cells was greatly increased. In addition, electrophysiological measurements revealed a dramatic reduction of dilution potentials in claudin-7-overexpressing cells compared to that of control cells. To determine which ions are responsible for the effects of claudin-7 overexpression on transepithelial electrical resistance and dilution potentials, we applied an ion substitution strategy. When NaCl was replaced with sodium aspartate, transepithelial electrical resistance was significantly decreased and dilution potentials were increased in claudin-7-overexpressing cells as compared to controls, the opposite effects from that of using NaCl. Furthermore, when NaCl was substituted by arginine-HCl or lysine-HCl, the increase in transepithelial electrical resistance was greater and the reduction in dilution potentials was smaller. Taken together, our studies demonstrated for the first time that the effect of claudin-7 overexpression in LLC-PK1 cells on paracellular transport is mediated through a concurrent decrease in the paracellular conductance to Cl– and an increase in the paracellular conductance to Na+. These results support the model that claudin-7 may form a paracellular barrier to Cl– while acting as a paracellular channel to Na+.
Basigin (EMMPRIN/CD147) interacts with integrin to affect cellular architecture
Authors: Curtin Kathryn D. , Meinertzhagen Ian A. , Wyman Robert J.
Published: June 2005

Basigin, an IgG family glycoprotein found on the surface of human metastatic tumors, stimulates fibroblasts to secrete matrix metalloproteases that remodel the extracellular matrix. Using Drosophila melanogaster we identify intracellular, matrix metalloprotease-independent, roles for basigin. Specifically, we found that basigin, interacting with integrin, is required for normal cell architecture in some cell types. Basigin promotes cytoskeletal rearrangements and the formation of lamellipodia in cultured insect cells. Loss of basigin from photoreceptors leads to misplaced nuclei, rough ER and mitochondria, as well as to swollen axon terminals. These changes in intracellular structure suggest cytoskeletal disruptions. These defects can be rescued by either fly or mouse basigin. Basigin and integrin colocalize to cultured cells and to the visual system. Basigin-mediated changes in the architecture of cultured cells require integrin binding activity. Basigin and integrin interact genetically to affect cell structure in the animal, possibly by forming complexes at cell contacts that help organize internal cell structure.
Positive Feedback Mechanism, Autocatalysis Mechanism, and Dependence on Atomic-Level Surface Structures in Electrochemical Oscillations for H2O2 Reduction on Pt Electrodes
Authors: Mukouyama Yoshiharu , Nakanishi Shuji , Nakato Yoshihiro
Published: June 2005

Electrochemical reduction of H2O2 on Pt electrodes shows a variety of oscillations, depending on the electrode potential, electrode illumination, the atomic-level flatness of the electrode surface, and the presence or absence of metal atoms and halogen atoms adsorbed to submonolayer amounts on the electrode surface. This is a unique feature of this oscillating system, helpful for deeper understanding of oscillation phenomena. In this article, the fundamental behavior and mechanism of oscillations, named oscillations A and B, for polycrystalline Pt electrodes are first described. A mathematical simulation for oscillation A shows clearly the presence of a positive feedback mechanism and an important role of adsorbed hydrogen atoms, called upd-H. The behavior of oscillation A, especially the oscillation period, is changed by electrode illumination, application of weak external potential pulses, and coupling with other oscillation systems. The oscillation period is also altered by adsorption of foreign metal atoms such as Cu, Ag, Au, and Ru on Pt to sub-monolayer amounts. New-type oscillations called oscillations C and D appear when small amounts of halide ions are added to the solution. The appearance of oscillations C and D is explained by assuming a catalytic effect of adsorbed halogen atoms and an autocatalytic effect of adsorbed OH group on the H2O2 reduction. Another new-type oscillation is observed when an atomically-flat single-crystal Pt(111) electrode is used. These results clearly show an important role of atomic-level structures of the electrode surface in electrochemical oscillations.
Numerical Study on the Chaotic Response of the Minimal Chemical Oscillator to a Sinusoidal Perturbation
Authors: Sasaki Yoshihiro
Published: June 2005

The chaotic response of the minimal chemical oscillator stimulated by a sinusoidal perturbation was studied by a computer-simulation method. Chaotic phase diagrams were obtained and two types of chaos were estimated. One was neighbored by fundamental 1/2 and fundamental 1/3 entrainment regions, and was followed by a quasiperiodic region. It contained two chaotic modes (relatively large-amplitude mode and relatively small-amplitude one on the Poincaré section (cos ωpt = 1)) and coexisted with the fundamental 1/3 harmonic mode. Other chaotic regions appeared when fundamental 1/1 and fundamental 1/2 entrainment regions came into contact with each other, and these were not in contact with any quasiperiodic regions. In this case Hopf bifurcations from the fundamental 1/1 harmonic mode to the 1/n (n/n) (n: integer) harmonic modes occurred first, and were followed by chaotic modes between the harmonic modes and the 1/n ((n−1)/n) harmonic ones. The coexistence of the chaotic mode and the 1/3 harmonic mode and the existence of two chaotic modes were compared with the behaviors of a one-dimensional dynamical system having a piecewise linear map.
Electrochemical Luminescence of ZnGa2O4 and ZnGa2O4 : Mn Semiconductor Electrodes. —Emission Mechanism under Cathodic and Anodic Polarization—
Authors: Ohtake Toshihito , Sonoyama Noriyuki , Sakata Tadayoshi
Published: June 2005

Electrochemical luminescence properties and mechanism of ZnGa2O4 and ZnGa2O4 : Mn (ZnGa2O4 doped with Mn) were studied. ZnGa2O4 disk showed an n-type semiconductor property after reduction in H2 atmosphere. Under cathodic polarization, the emission in a ZnGa2O4 electrode showed a broad peak at 485 nm in Na2S2O8 electrolyte solution. ZnGa2O4 : Mn exhibited a sharp emission peak at about 500 nm based on Mn2+, and a broad peak of ZnGa2O4 was also observed with increasing the cathodic bias. Under anodic polarization in Na2SO4 electrolyte, electrochemical luminescence was observed from the ZnGa2O4 electrode surface at +12.5 V (vs. Ag/AgCl) with two emission peaks at about 500 and 700 nm. The emission mechanism based on avalanche breakdown and impact excitation of emission centers by injected electrons is proposed. By adding K4[Fe(CN)6], KI, and KBr as reducing agents to the Na2SO4 electrolyte, the emission intensity was increased in the order KBr < KI < K4[Fe(CN)6]. Temperature dependence of the emission intensity suggests that electron transfer at the ZnGa2O4/electrolyte interface occurs equi-energetically from the occupied energy level of each reducing agent to the conduction band of ZnGa2O4.
Chemically Induced Dynamic Electron Polarization in the Photoreduction of Aromatic Ketones with ππ*-Type Triplet State
Authors: Kawai Akio , Yamamoto Tetsuya , Okutsu Tetsuo , Obi Kinichi
Published: June 2005

Chemically induced dynamic electron polarization (CIDEP) spectra of radicals produced in the photoreduction reaction of aromatic ketone/triethylamine systems were measured by time resolved ESR method. Anion radicals with net absorption (Abs) CIDEP were produced in ethanol with a base such as KOH, while ketyl type radicals with net emissive (Em) CIDEP have been formed in cyclohexane and benzene. Laser power dependence measurement indicates that net Em CIDEP of ketyl radicals is generated by a two-photon process while the production of ketyl radical itself is by one-photon process. Therefore, it was concluded that net Em CIDEP is generated through radical-triplet pair mechanism (RTPM) between the triplet state aromatic ketone and the produced ketyl radical. While RTPM is reasonably considered as an origin of net Em CIDEP for ketyl radicals, it is difficult to determine the CIDEP mechanism of the net Abs polarization of anion radicals in the present systems. Possible mechanisms were tentatively proposed for the present net Abs CIDEP generation.
Time-Resolved Measurements of the Gas-Phase Reaction of Mo2 (X 1Σg+) with Some Simple Molecules at Room Temperature
Authors: Ishikawa Yo-ichi , Matsumoto Yoshitaka , Wakabayashi Tomohiro
Published: June 2005

A multiphoton dissociation (MPD) of volatile metal carbonyl was applied for pulse production of neutral transition metal dimers in a gas-phase kinetic study. Its feasibility was discussed in the reaction systems of Mo2 with small molecules (O2, CO, NO, H2, SF6, NH3, and C2H4). Some potential problems, such as disturbances to the dimer production mechanism from the reactant addition and to neutral reaction kinetics from ionic species inevitably produced in the MPD of metal carbonyls, were experimentally examined. The transient concentration of Mo2 (X 1Σg+, ν = 0) produced by 266-nm MPD of Mo(CO)6 was measured by a laser-induced fluorescence (LIF) at 518.60 nm (A 1Σu+, ν″ = 0 ← X 1Σg+, ν′ = 0). The pseudo-first order decay rates of Mo2 were found to increase with increasing the concentration of some reactive species (O2, NO, and NH3). Our results obtained from time-resolved measurements were found to be almost consistent with the observations of Lian et al. (J. Phys. Chem., 98, 11637 (1994)) who prepared Mo2 by laser vaporization and measured its depletion in a fast-flow reactor.
89Y MAS NMR in Red Phosphor, Eu-Doped Y2O2S. Assignment of Peaks Shifted by Paramagnetic Eu3+, Spin Lattice Relaxation Time, and Eu Distribution
Authors: Harazono Toshie , Adachi Ryuji , Kijima Naoto , Watanabe Tokuko
Published: June 2005

89Y MAS (Magic angle spinning) NMR has been investigated to study the local environment of Y sites in a red phosphor, Eu doped-Y2O2S (Eu–Y2O2S), with varying the Eu content. Despite the presence of paramagnetic Eu3+ ions, high resolution spectra were acquired and a number of local environments were detected. The assignment of the resonances to different Y local environments was made on the basis of signal intensities, chemical shifts, and spin-lattice relaxation times (T1) in conjugation with the crystal structural data which were obtained by the Rietveld method. Besides the main peak in pure Y2O2S, four peaks caused by the –Eu species and ten peaks caused by the Eu––Eu species were distinguished in Eu–Y2O2S, where Y1 is the next nearest-neighbor Y site for the doped Eu atom, and –Eu and Eu––Eu are substituted by one and two Eu, respectively. Y atoms (Y2, Y3, ··· Yn), which are further from the second and more nearest-neighbors from Eu were observed at the same resonance position for all samples investigated with that of pure Y2O2S.

The T1 values of the 89Y signal were reduced from 6.6 h for pure Y2O2S to 230 s (10 mol% Eu–Y2O2S) for Yn (n ≥ 2), to several tens of seconds for Y1–Eu and to several seconds for Eu–Y1–Eu in Eu–Y2O2S. The Eu content to Y in the region where Eu atoms are randomly isolated was estimated from the intensity ratio of the total intensities of the four Y1 peaks to the main peak. T1 reduction and a line-broadening due to paramagnetic Eu3+ ions are discussed in relation to the distribution of Eu ions.
Quantum Control of the Photodissociation of Sodium Iodide
Authors: Hoki Kunihito , Ohtsuki Yukiyoshi , Kono Hirohiko , Fujimura Yuichi , Koseki Shiro
Published: June 2005

A quantum control of photodissocation of NaI to neutral atom fragments, NaI → NaI* → Na + I, was theoretically studied by using a locally optimized control method. The purpose of this control was to obtain as many neutral fragments as possible within one cycle of the nuclear vibration. The control was based on a pump-and-dump scheme. Weak and strong laser-field cases were used. The optimal dump pulses in both cases were shown to be of a linear time-dependent up-chirp type by analyzing their time- and frequency-resolved power spectra. This confirms the result predicted using a non-optimal control method in a previous paper (Chem. Phys. Lett., 231, 50 (1994)). The nuclear wavepacket propagations were also analyzed to see how photodissociation takes place when controlled pulses are used.
Flow-Type Chemiluminescence Detection Cell Using an Optical Fiber for Capillary Electrophoresis
Authors: Hashimoto Masahiko , Nakamura Takeshi , Tsukagoshi Kazuhiko , Nakajima Riichiro , Kondo Kazuo
Published: June 2005

A flow-type chemiluminescence detection cell using optical fiber was designed for capillary electrophoresis. The capillary was set up straight to the optical fiber with a certain distance in a Teflon® tube. Hydrogen peroxide was delivered through a three-way joint by a syringe pump and mixed with analytes at the capillary outlet. Luminol chemiluminescence was adapted for use with this detection cell. Analytical conditions, such as hydrogen peroxide flow rate, distance between the capillary and the fiber, and the reagent concentrations, were examined in detail with the cell. The present flow-type system provided a CL signal with high sensitivity, resolution, and reproducibility. The detection limit (S/N = 3) for luminol was 7.6 × 10−9 M (28 amol; 3.7 nl injected) with theoretical plate numbers of 130000—160000 and a relative standard deviation of 3.3% for the peak height (n = 10). A mixture sample of glycine, glycylglycine, and glycylglycylglycine, which were labeled with isoluminol isothiocyanate (2,3-dihydro-6-isothiocyanato-1,4-phthalazinedione), was also subjected to the present system. They were sensitively detected and represented with high resolution.
Adduct Polymers and Dimers of Rhodium(II) Pivalate with Pyrazine, 4,4′-Bipyridine, 1,4-Diazabicyclo[2.2.2]octane, Triethylamine, and Pyridine
Authors: Handa Makoto , Watanabe Mayumi , Yoshioka Daisuke , Kawabata Seiichiro , Nukada Ryoji , Mikuriya Masahiro , Azuma Hiroshi , Kasuga Kuninobu
Published: June 2005

Adducts of rhodium(II) pivalate with pyrazine (pyz), 4,4′-bipyridine (4,4′-bpy), and 1,4-diazabicyclo[2.2.2]octane (dabco), triethylamine (tea), and pyridine (py) have been prepared. The adducts with pyz, 4,4′-bpy, and dabco are polymers formulated as [Rh2(O2CCMe3)4(L)]n, (L = pyz, 4,4′-bpy, and dabco). A polymer structure with an alternating arrangement of the rhodium(II) dimer and ligands was confirmed by an X-ray structure analysis of the 4,4′-bpy adduct. The Rh–Rh bond distance is 2.395(1) Å which is in the range of those reported for the adducts of rhodium(II) carboxylates with axial aromatic nitrogen-donor ligands. The structure of the adduct dimers, [Rh2(O2CCMe3)4(L)2] (L = tea and py), was also confirmed for a tea-coordinated complex, which has considerably long axial Rh–N (2.391(8) Å) and Rh–Rh (2.413(1) Å) bonds. The reflectance-spectral and thermogravimetric data of all the adducts were obtained to examine the axial interaction between the rhodium(II) dimer core and the ligands.
Synthesis and Characterization of Some Cationic η3-Propargylpalladium Complexes
Authors: Tsutsumi Ken , Kawase Tomohiro , Kakiuchi Kiyomi , Ogoshi Sensuke , Okada Yuji , Kurosawa Hideo
Published: June 2005

Some cationic η3-propargylpalladium complexes were prepared upon treatment of the corresponding η1-propargyl- or η1-allenylbis(triphenylphosphine)palladium(II) chloride with Ag[BF4] or Na[BPh4]. The effectiveness of the latter reagent suggests that a η1-propargyl- or η1-allenyl(chloro)palladium complex equilibrates with a cationic η3-propargylpalladium complex with the liberation of a Cl− ligand. A qualitative comparison of trends in a series of analogous equilibrium systems suggests that the η3-coordination mode is favored to a greater extent when (i) propargyl ligands have an alkyl substituent at the propargylic position, (ii) phosphine ligands are bidentate, such as dppe, (iii) polar solvents are used, and (iv) the liberating ligand is a Cl− one. A possible implication of η3-coordination of propargyl ligands in a catalytic cycle of Pd-catalyzed transformations of propargylic or allenylic substrates is presented.
Extracted Species of Rare Earth Elements Using Bis(1,1,3,3-tetramethylbutyl)phosphinic Acid as an Extractant and Their Effective Mutual Separation by High-Performance Extraction Chromatography
Authors: Wang Qiu-quan , Huang Ben-li , Tsunoda Kin-ichi , Akaiwa Hideo
Published: June 2005

The possible extracted species of rare earth elements (REE) in bis(1,1,3,3-tetramethylbutyl)phosphinic acid (Hmbp)/cyclohexane–HNO3 system was proposed by a log–log plot analysis and a saturated extraction method as being [M(mbp)3(Hmbp)3] (M = REE). It was also verified by IR, 1H NMR spectra and element analysis of lutetium–Hmbp extracted species. The effective mutual separation of REEs was achieved on the Hmbp modified C-18 column by a pH gradient elution. Moreover, the degree of the mutual separation of europium(III) from gadolinium(III) was remarkably improved by adding glycollic acid in the mobile phase. A fine concentrate of Sm2O3, Eu2O3, and Gd2O3 from a rare earths smeltery was analyzed by the present method with the spectrophotometric detection after postcolumn derivatization with Arsenazo III.
Solvent Extraction Equilibria and Kinetics of Gallium(III) with 2-Thenoyltrifluoroacetone in the Absence and Presence of Trioctylphosphine Oxide in Toluene
Authors: Yamada Meri , Suganuma Shinya , Tanaka Ichiro , Sekine Tatsuya
Published: June 2005

The rate and equilibrium of solvent extraction of gallium(III) from aqueous perchlorate solutions into toluene with 2-thenoyltrifluoroacetone (Htta) was measured in the absence and presence of trioctylphosphine oxide (TOPO). A synergistic enhancement of the extraction was found when TOPO was added. When a correction was made for the association of Htta and TOPO in the organic phase which decreased their concentrations available for the extraction, the extracted adducts was found to be in the form of Ga(tta)3(TOPO)2. The rate of extraction was not high and it was dependent on the second order with respect to Htta and the inverse second order with respect to H+ in both the absence and the presence of TOPO. The rate was accelerated by addition of TOPO; the enhancement of the rate was proportional to the TOPO concentration.
Time-Resolved Near-Infrared Surface-Enhanced Raman Spectroscopy of a Surface-Confined Electrochemical Reaction of 9,10-Phenanthrenequinone
Authors: Ishioka Toshio , Uchida Tatsuya , Teramae Norio
Published: June 2005

A measurement system for time-resolved surface-enhanced Raman spectroscopy with a submillisecond time resolution was developed using a step-scan near-infrared Fourier-transform spectrometer and was applied to analyze a redox reaction of 9,10-phenanthrenequinone (PQ) adsorbed on a polycrystalline gold electrode. In the time-resolved surface-enhanced Raman spectra, both quinone and hydroquinone forms of PQ were recognized, but the intermediate species, semiquinone radicals, were not. It was suggested that the lifetime of the intermedeate species was shorter than 0.5 ms, which was the time resolution of the developed system.
Synthesis, Spectroscopy, Electrochemistry, and Mesomorphism of Triple-Decker Porphyrins Consisting of Two Cerium Ions and Three 5,15-Diarylporphyrins
Authors: Miwa Hideya , Kobayashi Nagao , Ban Kazue , Ohta Kazuchika
Published: June 2005

Triple-decker sandwich complexes, which consist of two cerium ions and three strip-like diarylporphyrins, have been synthesized and their spectroscopic and electrochemical properties and mesomorphism are reported and compared with those of the corresponding double deckers and the parent monomers. The Soret band of the triple-deckers lies at longer and shorter wavelengths than those of the double-deckers and monomers, respectively, while a sequence of small absorptions is observed in the Q band region. These are interpreted on the basis of knowledge of triple-deckers made from tetraphenylporphyrin and octaethylporphyrin. Magnetic circular dichroism (MCD) spectroscopy suggests that the Soret bands of the triple-deckers are a superimposition of at least two transitions to orbitally degenerate states. In the MCD spectra, Faraday A-terms are observed corresponding to each absorption band, suggesting that these triple-deckers take D4h or more plausibly D4d structures. Triple-deckers containing dialkoxyphenyl groups at the 5,15-positions of their parent porphyrin show a mesophase possessing both lamellar and columnar structures at lower temperatures and a columnar mesophase at higher temperatures, which differ in stacking distances. On the other hand, those containing tetraalkoxylated terphenyl groups at the 5,15-positions of their parent porphyrin show only a columnar mesophase with a single stacking distance. These differences in the mesomorphism are explained by differences of the magnitude of the steric hindrance of the side chains for rotation along the axis connecting the center of the three porphyrins.
Formation of Lanthanide Complexes with Bipyridine-Functionalized Amide Compounds and Their Unusually High Amide Reactivity
Authors: Kawaguchi Satoshi , Kajikawa Takeshi , Kaneko Mariko , Koshimizu Takahiro , Araki Koji
Published: June 2005

In the presence of a catalytic amount of lanthanide cations (Ln3+), the amide of 6-benzoylamino-6′-l-phenylalanylamino-2,2′-bipyridine (1a) was efficiently cleaved at 30 °C to give l-phenylalanine ester in methanol almost quantitatively. The reaction proceeded in the manner of the Michaelis–Menten type via the 1 : 1 1a–Ln3+ complex ([1a]/[Ln3+] molar ratio = 1); the half-life time of the scissile amide bond of the complex was as short as 2 min for the 1a–Dy3+ system. The reactions were highly specific to the structure of the substrates, requiring 2,2′-bipyridine having two acylamino side chains at the 6,6′-positions and an amino group at the α-position of the scissile carbonyl. The formation and structures of the less-reactive 6,6′-bis(benzoylamino)-2,2′-bipyridine (1d) with lanthanide cations were studied spectrophotometrically. They formed 1 : 1 complexes, and the formation constants (Ka) were on the order of 103—105 mol−1 dm3 in methanol at 30 °C. Coordination of the bipyridine nitrogens and the carbonyl oxygens was indicated in chloroform. However, coordination of the carbonyl oxygens was not observed in methanol. Detailed structures of the complexes are discussed in relation to their reactivity.
Solvolysis of 2,2-Dialkylvinyl Iodonium Salt: Alkyl Participation and Possibility of a Primary Vinylic Cation Intermediate
Authors: Okuyama Tadashi , Yamataka Hiroshi , Ochiai Masahito
Published: June 2005

Solvolysis of (E)- and (Z)-2-methyl-5-phenyl-1-pentenyl(phenyl)iodonium tetrafluoroborate (1·BF4) was carried out in various alcohols, acetic acid, and aqueous solutions at 60 °C. Products (after acid hydrolysis) include iodobenzene and 2-methyl-5-phenylpentanal as well as rearranged ones: 6-phenyl-2-hexanone, 6-phenyl-3-hexanone, 6-phenyl-2-hexyne, 6-phenyl-1,2-hexadiene, and 6-phenyl-2,3-hexadiene. The products of α-elimination, including 1-methyl-3-phenyl-1-cyclopentene, were also obtained in methanol and ethanol. Solvolysis of the E isomer (E)-1 is faster than that of (Z)-1 in every solvent examined. The percentage of rearrangement is higher with (E)-1 than with (Z)-1, and the main rearranged products are those of migration of the alkyl group trans to the iodonio group, but migration of the cis alkyl group is also involved. Theoretical calculations suggest that interconversion between the secondary vinylic cations by 1,2-hydride shift is rapid. These results show that a major heterolysis reaction occurs with β-alkyl participation to directly give a secondary vinylic cation, but stereochemistry of the unrearranged substitution products suggests that formation of the primary vinylic cation is also involved in less nucleophilic solvents like acetic acid and 2,2,2-trifluoroethanol.
Mechanism of the Benzophenone-Sensitized Photolysis of O-Benzoyl-N-(1-naphthoyl)-N-phenylhydroxylamine in Cationic Micellar Media
Authors: Kaneko Tsuyoshi , Tokue Tatsuya , Kubo Kanji , Sakurai Tadamitsu
Published: June 2005

The benzophenone-sensitized photolysis of the title hydroxylamine (1) in hexadecyltrimethylammonium chloride (HTAC) micelles was found to give benzoyloxy(2,3)- and phenyl(4,5)-migrated products, along with fragmentation products, 1-naphthanilide (6) and benzoic acid (7), which were obtained exclusively from the sensitized reaction in organic media. An analysis of the effects of added benzyl alcohol on the quantum yields for the reaction in HTAC micelles showed that the benzoyloxy-migrated products are derived from the amidyl-benzoyloxyl radical pair (that is present at the micellar surface), whereas the amidyl-phenyl radical pair (that is penetrated deeply into the micellar interior) is responsible for appearance of the phenyl-rearranged products. This effect of benzyl alcohol also confirmed that the hydrogen abstraction of the amidyl and benzoyloxyl radicals takes place in competition with the spin inversion of these triplet radicals. These interpretations were substantiated by the finding that the critical micelle concentration for HTAC is reduced in the presence of benzyl alcohol, but that the alcohol exerts only its very small effect on the aggregation number. On the other hand, the use of hexadecyltrimethylammonium bromide (HTAB) micelles instead of HTAC resulted in 2 and 3 in negligible quantum yields with increased quantum yields for the formation of 4—7. This intriguing result was explained in terms of (1) much less efffective hydrogen-bonding solvation of the assumed hot triplet radical pair in the more hydrophobic HTAB micellar surface as well as (2) heavy-atom effects on the intersystem crossing from the singlet amidyl-benzoyloxyl radical pair to the triplet one. Based on the quantum yields for the triplet-sensitized photolysis of 1 in HTAC–HTAB mixed micelles, it was demonstrated that the hydrogen-bonding solvation described above plays a major role in suppressing the benzoyloxy photorearrangement reaction in the HTAB micelle cage.
Different Aggregating Properties of Two Conformationally Frozen Isomers of a Water-Soluble Bridged Calix[6]arene
Authors: Akine Shigehisa , Goto Kei , Kawashima Takayuki , Okazaki Renji
Published: June 2005

Two conformationally frozen isomers (cone and 1,2,3-alternate) of a water-soluble calix[6]arene were synthesized and found to show the critical micelle concentrations quite different from each other, which was explained in terms of their monomer structures with different arrangements of the charged groups.
Simple Determination Method of Degree of Substitution for Starch Acetate
Authors: Ogawa Kazuo , Hirai Ikuo , Shimasaki Choichiro , Yoshimura Toshiaki , Ono Shin , Rengakuji Seichi , Nakamura Yuuko , Yamazaki Isao
Published: June 2005

To develop a simple method to determine the degree of substitution (dS) for starch ester, we prepared starch acetate with various dS values (0—3) and examined the mode of starch-iodine complex formation for the starch acetate by monitoring the ultraviolet-visible (UV-vis) spectra and their Fourier-transform infrared (FT-IR) spectral changes. The effect of acetylation on the formation of the starch-iodine complex was investigated by monitoring the decrease in absorbance at 680 nm (blue value). The blue value decreased by increasing the standard dS value determined by NMR for starch acetate, but two different correlations between the blue values and the dS values were observed for the low- and highly-substituted starch acetate. The FT-IR spectra for starch acetate particles were measured using a diffuse reflection method. The peak areas and absorbances of the bands assigned to the acetyl group showed a poor correlation with standard dS values from the NMR. On the other hand, the FT-IR peaks assigned to sodium acetate produced by saponification of the starch acetate could be detected using the ATR (attenuated total reflection) method; they showed a good correlation with the standard dS values from the NMR. From these results, it was concluded that the ATR method should be available for the dS determination of starch acetate.
Reversible Oxygen-Releasing from the Composite of Picketfence-Porphyrinatocobalt and Carbon in Response to a 1.5 V-Application
Authors: Nishide Hiroyuki , Suzuki Yoko , Tsuchida Eishun
Published: June 2005

5,10,15,20-Tetrakis(α-o-pivalamidophenyl)porphyrinatocobalt(II) (CoP) complexed with N-tritylimidazole in the solid state quickly and reversibly absorbed oxygen from air (14 cm3 O2/g), which was ascribed to a Co/dioxygen 1/1 adduct formation. The adduct formation was an exothermic reaction, and the absorbed oxygen was released above 65 °C. A disk (e.g., diameter 2 cm × 2 mm) was prepared with powders of the oxygen-absorbing, but electrically insulating, CoP complex and of electrically conductive carbon. The application of 1.5 V to the disk induced a temperature elevation in the disk, which momentarily released the absorbed oxygen. The oxygen-releasing and -absorbing cycle could be repeated more than 100 times, with a 5-min switching on-off interval under ambient conditions.
Construction of Defect-Diminished Fatty Acid Langmuir–Blodgett Film and Its Optical Waveguide Properties
Authors: Yanagida Masami , Takahara Atsushi , Kajiyama Tisato
Published: June 2005

A Langmuir–Blodgett (LB) film for a optical planar waveguide with a low optical propagation loss could be constructed from highly organized fatty acid monolayers prepared by a cooling multi-step creep method. The cooling multi-step creep method is the novel preparation technique to form a defect-diminished monolayer on the water surfaces on the basis of both the structural relaxation induced by area-creep and the control of thermal molecular motions in the monolayer. The fatty acid monolayer prepared by the cooling multi-step creep method was morphologically homogeneous and mechanically stable, even at a high surface pressure where the monolayer prepared by a conventional continuous compression method easily collapsed. The crystallographical and structural regularities of the monolayer and the LB film prepared by the cooling multi-step creep method were remarkably improved, compared with those of the monolayer and the LB film prepared by the conventional continuous compression method. The LB film waveguides prepared by the cooling multi-step creep method were morphologically homogeneous and structurally regular and could propagate incident light with a low optical propagation loss.
Pressure-Assisted Cold-Denaturation of Carboxypeptidase Y
Authors: Kunugi Shigeru , Yamamoto Hiroyuki , Makino Miki , Tada Tomoko , Uehara-Kunugi Yukiko
Published: June 2005

The pressure and temperature dependence of the hydrolytic rate of carboxypeptidase Y was studied in the range of 5—40 °C and 0.1—400 MPa. The iso-activity contours have more or less positive slopes. The pressure apparently disactivates the enzyme at a constant temperature, and the apparent activation volume (ΔV‡) became smaller with increasing temperature; ΔV‡app = − 46 ml mol−1 at 10 °C and −11 ml mol−1 at 40 °C. At a constant pressure, the activity increased with increasing temperature, and the evaluated activation enthalpy (ΔH‡) increased with an increase in pressure from 13 kcal mol−1 at 0.1 MPa to 25 kcal mol−1 at 400 MPa.

The intrinsic fluorescence spectrum changed with temperature and pressure and the highest intensity was recorded at ambient pressure and the lowest temperature, while the intensity decreased with increasing temperature or pressure. The intensity also decreased with decreasing temperature under elevated pressure, while the peak wavelength shifted to the red side according to the increase in pressure and temperature.

The disactivation of the catalysis and the decrease in the fluorescence peak intensity at a higher pressure and lower temperature were considered to be the so-called pressure-assisted cold-denaturation of the enzyme protein. Pressure can be a perturbation agent to “increase” the transition temperature above 0 °C.
A Spherical Potassium-Capped Vanadium Methylphosphonate as Another ε-Keggin Fragment, [H6KV12O27(VO4)(PO3CH3)3]5−
Authors: Yamase Toshihiro , Makino Haruyo , Naruke Haruo , Wéry Ana Maria San José
Published: June 2005

An [H3KV12O27(AsO4)4]6−-isostructural ε-Keggin fragment anion, [H6KV12O27(VO4)(PO3CH3)3]5−, was photochemically prepared. This K+-capped anion is formally built of nine VIVO6 octahedra, three PO3C tetrahedra, and four VVO4 tetrahedra, one of the latter being a central VO43− group. The capping K+ cation lies on the C3 axis and links two adjacent anion, to form a linear chain of the anions along c-axis.
Preparation of Visible-Light-Responsive Titanium Oxide Photocatalysts by Plasma Treatment
Authors: Takeuchi Koji , Nakamura Isao , Matsumoto Osamu , Sugihara Shinichi , Ando Masazumi , Ihara Tatsuhiko
Published: June 2005

The reduction of titanium dioxide (TiO2) by the hydrogen plasma treatment creates a new absorption band in the visible light region and is expected to create photocatalytic activity in this region. Anatase TiO2 powder, which has photocatalytic activity in the ultraviolet (UV) region, was treated using microwave and radio-frequency (RF) plasmas. The TiO2 was reduced thus having an oxygen deficiency. The RF-plasma-treated TiO2 absorbed visible light between 400 and 600 nm and showed a high activity in this region, as measured by the oxidative removal of nitric oxide from the gas phase. The plasma-treated TiO2, which can be easily produced on a large scale, is expected to have a higher efficiency in utilizing solar energy than the raw material.
Fatigue Mechanism of Photochromic 1,2-Bis(3-thienyl)perfluorocyclopentene
Authors: Higashiguchi Kenji , Matsuda Kenji , Yamada Taro , Kawai Tsuyoshi , Irie Masahiro
Published: June 2005

Non-substituted 1,2-bis(3-thienyl)perfluorocyclopentene 1a was synthesized and its photochromic reactivity was compared with 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene 4a. Upon irradiation with ultraviolet light 1a easily decomposed and two kinds of by-products were produced in addition to the normal closed-ring isomer. The structures of the by-products were determined by X-ray crystallographic analysis.
Palladium-Catalyzed Coupling Reaction of Fluoroalkylated Propargyl Mesylates with Organozinc Reagents: Novel Synthesis of Optically Active Fluorine-Containing Trisubstituted Allenes
Authors: Konno Tsutomu , Tanikawa Mitsuru , Ishihara Takashi , Yamanaka Hiroki
Published: June 2005

In the presence of 5 mol% of tetrakis(triphenylphosphine)palladium(0), the reaction of chiral fluorinated propargyl mesylates with a variety of organozinc reagents proceeded smoothly in a highly stereoselective fashion to give the corresponding optically active fluorine-containing trisubstituted allenes in good yields without any loss of optical purity through the reaction.
Regioselective Synthesis of Prenylisoflavones: Syntheses of Luteone and Luteone Hydrate
Authors: Tsukayama Masao , Wada Hironari , Kishida Masashi , Nishiuchi Masaki , Kawamura Yasuhiko
Published: June 2005

The palladium-catalyzed coupling reaction of 6-iodoisoflavone, prepared from 3′-iodoacetophenone derivative, with 2-methyl-3-butyn-2-ol gave the 6-alkynylisoflavone derivative, which was hydrogenated to give the 6-alkylhydroxyisoflavone (luteone hydrate) 2. Dehydration of 2 gave 2′,4′,5,7-tetrahydroxy-6-prenylisoflavone (luteone).
Preparation and Thermal Behavior of 3,3,4,4-Tetrafluorocyclobutane-1,2-diols: A New Family of Cyclobutane-1,2-diols
Authors: Kobayashi Satoru , Yamamoto Youko , Amii Hideki , Uneyama Kenji
Published: June 2005

Thermal dimerization of 2,2-difluoro enol silyl ethers led to 3,3,4,4-tetrafluorocyclobutanes. The [2+2] cycloaddition proceeded in a “head-to-head” fashion to afford the cyclobutanes containing the trans and cis stereoisomers. The cyclobutanes were transformed to tetrafluorocyclobutane-1,2-diols by desilylation.
Synthesis of Novel Lamellar Iron Phosphate
Authors: Guo Xuefeng , Ding Weiping , Wang Xiaoshu , Yan Qijie
Published: June 2005

Meso-structured lamellar iron phosphates with varied d-spacings have been synthesized from ferric acetylacetonate and n-alkylammonium dihydrogenphosphates, which serve as both template and reactant.
Novel C60-Containing Ultra-thin Film Based on Diazoresin
Authors: Cao Tingbing , Gu Zhennan , Zhou Xihuang , Cao Weixiao
Published: June 2005

A kind of multilayer ultra-thin films was fabricated from diazoresin and water-soluble fullerene derivative C60(Ona)n. Under irradiation of UV light, following the decomposition of -N2+ group of diazoresin, the bond nature between the layers of the film will convert from ionic to covalent. As a result the irradiated film possesses high stability towards polar solvents.
Remarkable Effect of Manganese Center on Catalytic Activity for Decomposition of Hydrogen Peroxide
Authors: Kishida Asako , Taguchi Akira , Mizuno Noritaka
Published: June 2005

The structures of manganese centers remarkably influenced the catalytic activities for the decomposition of hydrogen peroxide and tri-manganese-substituted silicotungstate, [α-SiW9{MnIII(H2O)}3O37]7−, was the most active among the polyoxometalates tested and other inorganic manganese compounds.
Preparation and Properties of 2,2-Bissilyl-1,3-dithia-2-silacyclopent-4-enes and Related Compounds
Authors: Tsutsui Shinobu , Takahashi Masae , Sakamoto Kenkichi
Published: June 2005

Several 1,3-dithia-2-silacyclopent-4-ene (dithiasilole) derivatives were prepared by the reactions of cis-NaS–HC=CH–Sna with the corresponding dichlorosilanes. The compounds formed charge-transfer (CT) complexes with tetracyanoethylene in CH2Cl2. The UV–vis spectra of the CT complexes indicated that the ionization potential of 2,2-bis(trimethylsilyl)dithiasilole was smaller than that of 2,2-dimethyldithiasilole. The results were explained by the σ(Si–R)–π interactions resulting in a higher HOMO level. Ab initio MO calculations supported the experimental results.
Cyclization of 1,2-Disilacyclohexa-3,5-dienes Initiated by Electron Transfer Reactions with TCNE
Authors: Mochida Kunio , Shimizu Hiromi , Nanjo Masato
Published: June 2005

Thermal reaction of 1,2-disilacyclohexa-3,5-dienes with tetracyanoethylene (TCNE) gave 8-amino-6,6,11,11-tetramethyl-2,3,4,5-tetraphenyl-7-aza-6,11-disilatricyclo[5,3,0,12,5]undeca-3,8,10(1)-triene-9,10-dicarbonitrile through a charge-transfer complex.
Preparation of Polycrystalline HT-LiCoO2 Using Molten Salt Synthesis Method at 280 °C
Authors: Hong Young-Sik , Han Chi-Hwan , Kim Keon
Published: June 2005

Polycrystalline HT-LiCoO2 powders with homogeneous size distribution have been synthesized at 280 °C by the molten salt synthesis method using 0.59 LiNO3–0.41 LiOH as a flux. These powders exhibit a good electrochemical behavior without further heat treatment at higher temperatures.
Transmetallation Reaction of 1-Phenylthio- or 1-Tolylthio-2-(2,4,6-tri-t-butylphenyl)-2-phosphaethenyllithium with Copper(II) and Mercury(II)
Authors: Ito Shigekazu , Yoshifuji Masaaki
Published: June 2005

Transmetallation of bulky 1-arylthio-2-(2,4,6-tri-t-butylphenyl)-2-phosphaethenyllithiums with copper(II) and mercury(II) afforded the corresponding 1,4-diphospha-1,3-butadiene derivatives as homocoupled products and organomercury compounds, respectively, which were analyzed by X-ray crystallography.
Lifetime of Singlet Oxygen (1Δg) in Liquid and Supercritical Carbon Dioxide
Authors: Okamoto Masami , Takagi Toshiharu , Tanaka Fujio
Published: June 2005

The lifetime of singlet oxygen, 1O2 (1Δg), in liquid and supercritical carbon dioxide (SCF CO2) was determined by a time-resolved phosphorescence method. In both the systems, the lifetime decreased significantly with increasing pressure. The pressure dependence of the lifetime in SCF CO2 was satisfactorily interpreted by the quenching mechanism in liquid phase that involves solvent cage.
Total Syntheses of Phycocyanobilin Derivatives Bearing a Modified A-Ring toward the Structure/Function Analysis of Phytochrome
Authors: Sawamoto Daisuke , Nakamura Hiroshi , Kinoshita Hideki , Fujinami Shuhei , Inomata Katsuhiko
Published: June 2005

Phycocyanobilin (PCB) derivatives bearing a modified A-ring, including 3,3′-dihydrogenated PCB derivatives, were efficiently synthesized in free acid forms by applying our original methods for the preparation of A-, A/B-, and C/D-ring components toward the structure/function analysis of phytochrome.
Unusually High Reactivity of cis-Cp*W(CO)2(MeCN)Me to CO Insertion Reaction with Isocyanide
Authors: Sakaba Hiroyuki , Tsukamoto Masanori , Kabuto Chizuko , Horino Hiroshi
Published: June 2005

The reaction of cis-Cp*W(CO)2(MeCN)Me with CNtBu gave a mixture of the acetonitrile substitution products cis- and trans-Cp*W(CO)2(CNtBu)Me and the CO insertion products cis- and trans-Cp*W(CO)(CNtBu)2(COMe). The substitution was favored at room temperature, while the insertion was favored at low temperature.
Protonation-Induced Conformational Changes of N,N,N′,N′-Tetramethylethylenediamine. Importance of Strong N–H+···N Hydrogen Bonding
Authors: Ohno Keiichi , Kuriyama Taku , Fukuda Makoto , Yoshida Hiroshi , Matsuura Hiroatsu
Published: June 2005

The effect of protonation on the conformation of N,N,N′,N′-tetramethylethylenediamine (TMEDA) has been studied by Raman spectroscopy and ab initio theory. TMEDA and TMEDAH22+ molecules assume predominantly the trans NC–CN conformation in aqueous solution, while a large number of TMEDAH+ molecules assume the gauche NC–CN conformation, as stabilized by strong intramolecular 1,4-N–H+···N hydrogen bonding.
Alternative Synthesis of (Z)-1-Aryl-1-(tributylstannyl)-2-(triethylgermyl)ethenes and the Unprecedented Germyl 1,2-Migration during the Destannylation of the Adducts
Authors: Nakano Taichi , Senda Yoshiya , Miyamoto Takashi
Published: June 2005

A specific combination catalyst, Pd(dba)2 and 4-ethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, effectively catalyzed the addition of tributyl(triethylgermyl)stannane to arylacetylenes in tetrahydrofuran to give (Z)-1-aryl-2-(germyl)-1-(stannyl)ethenes in high yields. The (Z)-1-aryl-2-(germyl)-1-(stannyl)ethenes were subject to the unprecedented germyl 1,2-migration during the destannylation using HI / TBAI in toluene to produce 1-aryl-1-(germyl)ethenes in high yields.
Synthesis of Mesoporous TiO2 Spheres under Static Condition
Authors: Wang Lianzhou , Tomura Shinji , Maeda Masaki , Ohashi Fumihiko , Inukai Keiichi , Suzuki Masaya
Published: June 2005

Mesoporous TiO2 with well-defined spherical morphologies has been synthesized under quiescent condition via the template-assisted slow hydrolysis of titanium alkoxide in environmental humidity.
Ajanoside, a Xanthine Oxidase Inhibitor with a Novel Skeleton from Ajania fruticulosa
Authors: Meng Jun Cai , Tan Ren Xiang
Published: June 2005

The structure of ajanoside, a xanthine oxidase inhibitor with a novel skeleton isolated from the aerial parts of Ajania fruticulosa, was determined to be [2,2-bis(4-hydroxy-3-methoxyphenyl)-4-oxo-1,3-dioxin-5-yl]methyl β-d-glucopyranoside on the basis of extensive spectroscopic analyses.
Observation of Highly Stable Radical Anions of Ladder Oligosilanes
Authors: Kyushin Soichiro , Miyajima Yoshifumi , Matsumoto Hideyuki
Published: June 2005

The radical anions of ladder oligosilanes were generated by the reduction with alkali metals and observed by UV–visible–NIR and ESR spectroscopies. The radical anions of the longer ladder oligosilanes are highly stable at room temperature.