bluuebunny/crossref_metadata_2025 huggingface dataset:
LOW TEMPERATURE PROPERTIES OF 2D CORRELATED ELECTRONS IN WEAKLY DISORDERED MATERIALS
Authors: NEILSON DAVID , GELDART D. J. W.
Published: December 2003

Transport properties of extremely high purity two-dimensional (2D) electron systems at low temperatures are still not well understood either experimentally or theoretically, even though these systems are fast becoming a mainstream basis of computing devices. In fact there are two separate issues to be resolved. The first of these has attracted the more attention. This is the existence of a quantum phase transition (the metal-insulator transition) in the low density 2D system at zero temperature. Experimentally, in spite of claims, from existing data at finite temperatures there is no conclusive evidence either way on the existence of a T = 0 quantum phase transition. There is a need for a unified theory encompassing, on the same level, both insulating and metallic behaviour to predict the cross-over. We propose a semi-empirical one parameter renormalisation group equation for the temperature dependent resistivity of a 2D electron system with weak disorder. The renormalisation group equation has a physically meaningful insulating limit and it predicts a metallic ground state of zero resistance at higher electron densities. The resulting temperature dependence of the resistivity is found to give a good fit to experimental data near the separatrix. The second issue is the mechanism behind the sudden change in the temperature dependence of the resistivity, as is actually observed at low but non-zero temperatures, T = 0.1 to 2 K. This phenomenon is well-documented experimentally and it is of interest in its own right whether or not there is an actual transition at T = 0. We present direct evidence of the important role of the electron Coulomb repulsion and exchange in determining these finite temperature properties by noting an empirical relationship between the critical density at the bifurcation point and parallel magnetic field. The relationship is controlled by properties of the electron-electron correlation function for the 2D electron system. This result provides direct evidence of the central role of the Coulomb repulsion and exchange in driving the bifurcation phenomenon.
TRANSPORT ANOMALIES AND MARGINAL FERMI-LIQUID EFFECTS AT A QUANTUM CRITICAL POINT
Authors: BELITZ D. , SESSIONS SHARON L. , KIRKPATRICK T. R. , MERCALDO M. T. , NARAYANAN R. , VOJTA THOMAS
Published: December 2003

The behaviour of the conductivity and the density of states, as well as the phase relaxation time, of disordered itinerant electrons across a quantum ferromagnetic transition is discussed. It is shown that critical fluctuations lead to anomalies in the temperature and energy dependence of the conductivity and the tunnelling density of states, respectively, that are stronger than the usual weak-localisation anomalies in a disordered Fermi liquid. This can be used as an experimental probe of the quantum critical behaviour. The energy dependence of the phase relaxation time at criticality is shown to be that of a marginal Fermi liquid.
ROTATIONAL BAND STRUCTURE OF LOW-LYING EXCITATIONS IN SMALL HEISENBERG SYSTEMS
Authors: SCHNACK JÜRGEN , LUBAN MARSHALL , MODLER ROBERT
Published: December 2003

We derive the low-temperature properties of the giant molecular magnet { Mo 72 Fe 30}, where 30 Fe 3+ paramagnetic ions occupy the sites of an icosidodecahedron and interact via isotropic nearest-neighbour antiferromagnetic Heisenberg exchange. The key idea of our model is that the low-lying excitations form a sequence of "rotational bands", i.e. for each such band the excitation energies depend quadratically on the total spin quantum number. As rotational bands characterise the spectra of many magnetic molecules our method opens a new road towards a description of their low-temperature behaviour which is not accessible otherwise.
RECENT DEVELOPMENTS IN THE NUCLEAR MANY-BODY PROBLEM
Authors: FURNSTAHL R. J.
Published: December 2003

The study of quantum chromodynamics (QCD) over the past quarter century has had relatively little impact on the traditional approach to the low-energy nuclear many-body problem. Recent developments are changing this situation. New experimental capabilities and theoretical approaches are opening windows into the richness of many-body phenomena in QCD. A common theme is the use of effective field theory (EFT) methods, which exploit the separation of scales in physical systems. At low energies, effective field theory can explain how existing phenomenology emerges from QCD and how to refine it systematically. More generally, the application of EFT methods to many-body problems promises insight into the analytic structure of observables, the identification of new expansion parameters, and a consistent organisation of many-body corrections, with reliable error estimates.
THE BETHE–BRUECKNER–GOLDTONE THEORY OF THE NUCLEAR EQUATION OF STATE AND NEUTRON STARS
Authors: BALDO M. , BURGIO G. F.
Published: December 2003

The microscopic many-body theory of the Nuclear Equation of State is discussed in the framework of the Bethe–Brueckner–Goldstone method. The expansion is extended up to the three hole-line diagrams contribution. The Brueckner equation for the two-body G-matrix and the Bethe–Fadeev equation for the three-body scattering matrix are solved both for the gap and continuous choices of the single particle potential. For symmetric and pure neutron matter strong evidence of convergence in the expansion is found. Once three-body forces are introduced, the phenomenological saturation point is reproduced. In order to study neutron stars static properties, the theory is extended to include strangeness, and the possible quark-gluon plasma component is described in the simplified MIT bag model. The results for the mass and radius of neutron stars are briefly discussed.
EXCITON-PHONON PACKETS WITH BOSE–EINSTEIN CONDENSATE
Authors: ROUBTSOV D. , LÉPINE Y.
Published: December 2003

We discuss the possibility for a moving droplet of excitons and phonons to form a coherent state inside the packet. We describe such an inhomogeneous state in terms of Bose–Einstein condensation and prescribe it a macroscopic wave function. Existence and, thus, coherency of such a Bose-core inside the droplet can be checked experimentally if two moving packets are allowed to interact.
FROM LIGHT NUCLEI TO NUCLEAR MATTER: THE ROLE OF RELATIVITY?
Authors: COESTER F.
Published: December 2003

The success of non-relativistic quantum dynamics in accounting for the binding energies and spectra of light nuclei with masses up to A=10 raises the question whether the same dynamics applied to infinite nuclear matter agrees with the empirical saturation properties of large nuclei. The simple unambiguous relation between few-nucleon and many-nucleon Hamiltonians is directly related to the Galilean covariance of nonrelativistic dynamics. Relations between the irreducible unitary representations of the Galilei and Poincaré groups indicate that the "nonrelativistic" nuclear Hamiltonians may provide sufficiently accurate approximations to Poincaré invariant mass operators. In relativistic nuclear dynamics based on suitable Lagrangeans the intrinsic nucleon parity is an explicit, dynamically relevant, degree of freedom and the emphasis is on properties of nuclear matter. The success of this approach suggests the question how it might account for the spectral properties of light nuclei.
COUPLED CLUSTER TREATMENTS OF QUANTUM MAGNETS: TWO EXAMPLES
Authors: KRÜGER SVEN E. , FARNELL DAMIAN J. J. , RICHTER JOHANNES
Published: December 2003

In this article we study the ground-state properties of two square-lattice Heisenberg quantum spin models with competing bonds using a high-order coupled cluster treatment. The first model is a spin-half model with competing nearest-neighbour bonds with and without frustration. We discuss the influence of quantum fluctuations on the ground-state phase diagram and in particular on the nature of the zero-temperature phase transitions from phases with collinear magnetic order at small frustration to phases with noncollinear spiral order at large frustration. The second model is a highly frustrated ferrimagnet, which contains one sublattice (A) entirely populated with spin-one spins and an other sublattice (B) entirely populated with spin-half spins. Sublattice A sites are nearest-neighbours to sublattice B sites and vice versa and frustration is introduced by next-nearest-neighbour bonds. The model shows two collinear ordered phases and a noncollinear phase in which (classically) the spin-one spins are allowed to cant at an angle. Both examples show that the coupled-cluster method is able to describe the zero-temperature transitions well and provides a consistent description of collinear, noncollinear, and disordered phases, for cases in which other standard techniques (e.g. the quantum Monte Carlo technique for spin systems which are frustrated) are not applicable.
A FINITE-TEMPERATURE GENERALISATION OF THE COUPLED CLUSTER METHOD: A NON-PERTURBATIVE ACCESS TO GRAND PARTITION FUNCTIONS
Authors: MANDAL SEIKH HANNAN , GHOSH RATHINDRANATH , SANYAL GOUTAM , MUKHERJEE DEBASHIS
Published: December 2003

We present here a succinct account of the finite-temperature generalisation of the coupled cluster (CC) method. It requires the concept of thermal normal ordered products whose Boltzmann trace is zero. The basic idea is to express the Boltzmann operator as a normal ordered exponential containing cluster operators and a number, and express the free energy as a logarithm of a suitable Boltzmann trace, where only the number part in the ordered exponential survives. The free energy is manifestly extensive. Free energies of Lipkin model and anharmonic oscillators obtained from the grand partition function are discussed as example applications.
COUPLED-CLUSTER APPROACH TO CORRELATION IN SMALL MOLECULES: ENERGY VERSUS AMPLITUDE CORRECTED METHODS
Authors: PALDUS J. , LI X.
Published: December 2003

The coupled cluster method, which is based on the exponential Ansatz for the wave operator, found a particularly fertile ground in quantum chemical investigations of the molecular electronic structure, where the many-electron correlation effects play a crucial role and where this approach became the method of choice, particularly when handling nondegenerate ground states. The objective of this contribution is to provide a brief historical perspective on some current challenges of the coupled cluster methodology and to outline some most recent attempts at their solution.
COUPLED CLUSTER CALCULATIONS OF THE SCHWINGER MODEL IN HAMILTONIAN LATTICE GAUGE THEORY
Authors: MCDONALD REUBEN , WALET NIELS R.
Published: December 2003

The Schwinger Model, or quantum electrodynamics in 1+1 dimensions is a simple, yet non-trivial gauge theory. We investigate the Hamiltonian form of the Schwinger model defined of a spatial lattice with massive staggered fermions using the normal coupled cluster method (NCCM). We concentrate on the ground state of the model, studying the ground state energy as a function of coupling and fermion mass.
CONTROL OF QUANTUM SYSTEMS
Authors: CLARK JOHN W. , LUCARELLI DENNIS G. , TARN TZYH-JONG
Published: December 2003

A quantum system subject to external fields is said to be controllable if these fields can be adjusted to guide the state vector to a desired destination in the state space of the system. Fundamental results on controllability are reviewed against the background of recent ideas and advances in two seemingly disparate endeavours: (i) laser control of chemical reactions and (ii) quantum computation. Using Lie-algebraic methods, sufficient conditions have been derived for global controllability on a finite-dimensional manifold of an infinite-dimensional Hilbert space, in the case that the Hamiltonian and control operators, possibly unbounded, possess a common dense domain of analytic vectors. Some simple examples are presented. A synergism between quantum control and quantum computation is creating a host of exciting new opportunities for both activities. The impact of these developments on computational many-body theory could be profound.
A FOURTH ORDER REAL-SPACE ALGORITHM FOR SOLVING LOCAL SCHRÖDINGER EQUATIONS
Authors: KROTSCHECK E. , AUER J. , CHIN S. A.
Published: December 2003

We describe a rapidly converging algorithm for solving the Schrödinger equation with local potentials in real space. The algorithm is based on evolving the Schrödinger equation in imaginary time by factorizing the evolution operator e -εH to fourth order with purely positive coefficients. The states |ψj> and the associated energies extracted from the normalisation factor e -εEj converge as [Formula: see text]. Our algorithm is at least a factor of 100 more efficient than existing second order split operator methods. We apply the new scheme to a spherical jellium cluster with 20 electrons. We show that the low-lying eigenstates converge very rapidly and that the algorithm does not lose any of its effectiveness for very steep potentials.
Noise-induced stress response and hearing loss in goldfish (Carassius auratus)
Authors: Smith Michael E. , Kane Andrew S. , Popper Arthur N.
Published: December 2003

Fishes are often exposed to environmental sounds such as those associated with shipping, seismic experiments, sonar and/or aquaculture pump systems. While efforts have been made to document the effects of such anthropogenic(human-generated) sounds on marine mammals, the effects of excess noise on fishes are poorly understood. We examined the short- and long-term effects of increased ambient sound on the stress and hearing of goldfish (Carassius auratus; a hearing specialist). We reared fish under either quiet(110-125 dB re 1 μPa) or noisy (white noise, 160-170 dB re 1 μPa)conditions and examined animals after specific durations of noise exposure. We assessed noise-induced alterations in physiological stress by measuring plasma cortisol and glucose levels and in hearing capabilities by using auditory brainstem responses. Noise exposure did not produce long-term physiological stress responses in goldfish, but a transient spike in plasma cortisol did occur within 10 min of the noise onset. Goldfish had significant threshold shifts in hearing after only 10 min of noise exposure, and these shifts increased linearly up to approximately 28 dB after 24 h of noise exposure. Further noise exposure did not increase threshold shifts, suggesting an asymptote of maximal hearing loss within 24 h. After 21 days of noise exposure, it took goldfish 14 days to fully recover to control hearing levels. This study shows that hearing-specialist fishes may be susceptible to noise-induced stress and hearing loss.
Development of respiratory function in the American locustSchistocerca americanaI. Across-instar effects
Authors: Greenlee Kendra J. , Harrison Jon F.
Published: December 2003

We tested the hypothesis that oxygen delivery from the atmosphere to the tissues becomes more difficult as grasshoppers increase in body size throughout development due to increases in tracheal length. If this is true,then older, larger grasshoppers should have smaller safety margins [higher critical oxygen partial pressures (PO2s)] for oxygen delivery than younger, smaller grasshoppers. We exposed grasshoppers of first, third and fifth instars and adults to decreasing levels of atmospheric O2 and measured their ventilatory responses. Contrary to our prediction, we found that larger grasshoppers had critical PO2s eight times lower than juveniles due in part to their threefold lower mass-specific metabolic rates and their ability to quadruple convective gas exchange. Adults more than doubled abdominal pumping frequency and increased tidal volume by 25% as PO2 decreased fourfold, whereas the youngest juveniles showed no such responses. This study indicates that juveniles may be more susceptible to hypoxia in natural situations, such as exposure to high altitude or restricted burrows. Also, larger size is not necessarily correlated with a smaller safety margin for oxygen delivery in insects.
Allometry of maximum vertical force production during hovering flight of neotropical orchid bees (Apidae: Euglossini)
Authors: Dillon Michael E. , Dudley Robert
Published: December 2003

The ability of orchid bees to generate vertical forces was evaluated using a load-lifting method that imposed asymptotically increasing loads during ascending flight, ultimately eliciting maximum forces while hovering. Among 11 orchid bee species varying by approximately an order of magnitude in body mass, the capacity to produce vertical forces expressed relative either to body weight or to flight muscle weight declined linearly with increased body mass. Allometric analysis of log-transformed data, by contrast, found maximum vertical force to scale isometrically with body mass, but also to exhibit a slightly negative allometry with respect to flight muscle mass. Maximum stroke amplitude at limiting loads averaged 140° and was remarkably constant among species, a result consistent with anatomical constraints of the hymenopteran thorax on wing motions. By contrast, wing-beat frequencies during maximum performance declined with increasing body mass. Repeated lifting by individual bees reduced performance only when the number of consecutive lifts exceeded 15. Variation in linear mass density of the lifted load did not systematically alter performance estimates, although measurements on one species in two consecutive years at different thermal environments yielded significant differences in estimates of maximum force production. These findings suggest an adverse scaling of vertical force production at greater body mass even if flight muscle mass scales isometrically.
Stimulation of the α-adrenoceptor triggers the venom production cycle in the venom gland of Bothrops jararaca
Authors: Kerchove Celine M. , Carneiro Sylvia M. , Markus Regina P. , Yamanouye Norma
Published: December 2003

The noradrenergic innervation of Bothrops jararaca venom gland is thought to be important in the production and secretion of venom. We investigated the characteristics of the α-adrenoceptor in the venom gland and its role in venom production. This receptor had relatively low sensitivity to noradrenaline (pD2=4.77±0.09, N=7)and to phenylephrine (pD2=3.77±0.06, N=11). The receptor became desensitized just after venom extraction (pD2 to phenylephrine fell to 3.27±0.02, N=6) and the sensitivity remained low for at least 15 days, returning to normal 30 days after venom extraction, by which time the snake was ready for a new cycle of venom production. Incubation of secretory cells with noradrenaline(10–4 mol l–1 for 5 min) reducedα-adrenoceptor sensitivity to the level seen after venom extraction. Blockade of catecholamine production with reserpine abolished the enlargement of the rough endoplasmic reticulum and the activation of the Golgi apparatus that are normally seen after venom extraction, and the venom production was restored by a single subcutaneous (s.c.) injection of phenylephrine (100 mg kg–1) immediately after venom extraction. Our data suggest that stimulation of the α-adrenoceptor during or shortly after biting is essential for the onset of the venom production cycle.
Strikes and startles of northern pike (Esox lucius): a comparison of muscle activity and kinematics between S-start behaviors
Authors: Schriefer Julie E. , Hale Melina E.
Published: December 2003

S-starts are a major class of fast-start behaviors that serve diverse locomotor functions in fishes, playing roles in both feeding strike and escape startle events. While movement patterns are similar during strike and startle,their motor control mechanisms have not been compared. To investigate heterogeneity in S-start responses and to test the hypothesis that S-starts are generated by the same patterns of muscle activity regardless of the behavioral context in which they function, we examined kinematic and muscle activity patterns of northern pike (Esox lucius) performing feeding and escape S-starts. Movements were recorded with high-speed video (250 Hz). Muscle activity was recorded from seven electrodes, one in the left adductor mandibulae and bilaterally in the anterior, midbody and posterior epaxial white muscle. Although S-shaped movements are produced in both feeding and escape, kinematics and electromyogram (EMG) patterns differ. Stage 1(pre-propulsive movement) is significantly slower and more variable during feeding strikes and involves caudal bending with less rostral movement than recorded for startle behaviors. Correspondingly, there is strong caudal muscle activity prior to rostral activity during strikes, whereas in startles caudal muscle activity had near simultaneous onset with contralateral rostral activity. Onset of jaw muscle activity occurred significantly after the onset of axial muscle activity during feeding strikes. By contrast, during startles,jaw activity onset was nearly simultaneous with the onset of axial muscle activity. Stage 2 kinematics generally did not differ between the strike and startle; however, EMGs indicate that stage 2 movements are generated by different patterns of muscle activity for the two behaviors. Although strikes and startles are similar in their propulsive performance, they appear to be initiated and driven by fundamentally different motor control mechanisms. We suggest that S-start startle behavior is mediated by a simple system of descending reticulospinal input to spinal neurons while the S-start strike involves a more complex neural circuit, allowing greater modulation of stage 1 movements while maintaining high stage 2 performance.
First Example of Polydiacetylene from Diacetylene Monomer with Directly Linked Thienyl Sidegroup for Third-order Nonlinear Optics
Authors: Sarkar Abhijit , Okada Shuji , Matsuda Hiro , Nakanishi Hachiro
Published: December 2003

This work reports the first example of polydiacetylene(PDA) which has one of the side groups as a thienyl moiety directly linked to the π-conjugated backbone. The monomer, 8-(2-thienyl)-5,7-octadiynyl N-phenylcarbamate, undergoes solid state polymerisation via 1,4-addition reaction to yield the corresponding polydiacetylene. Te third order nonlinear optical susceptibility of the polymer has also been evaluated.
Synthesis and Luminescence Properties of Ru2/Cu, Ru2/Ni, and Ru2/Os Mixed Metal Polypyridine Complexes Bound by 1,3,5-Triethynylenebenzene
Authors: Osawa Masahisa , Sonoki Hirotaka , Hoshino Mikio , Wakatsuki Yasuo
Published: December 2003

Novel polypyridine metal complexes have been prepared, wherein two (terpy)2Ru units and one (bipy)3M (M = Cu, Os) or (bipy)Ni(H2O)4 unit (terpy = 2,2′:6,6′-terpyridine, bipy = 2,2′-bipyridine) are bonded to 1,3,5-positions of a benzene ring via ethynylene bridges. Photophysical study of these hetero trinuclear complexes has indicated effective electronic energy transfer between the metal components can take place.
Transition Metal-Catalyzed Cyclization of 2-Allylphenol to 2,3-Dihydro-2-methylbenzofuran without β-Elimination
Authors: Hori Kazushige , Kitagawa Hideki , Miyoshi Akio , Ohta Tetsuo , Furukawa Isao
Published: December 2003

The intramolecular nucleophilic addition of 2-allylphenol was catalyzed by RuCl3·nH2O/AgOTf–PPh3–Cu(OTf)2 to afford 2,3-dihydro-2-methylbenzofuran in good yield, while 2-(3-butenyl)phenol was converted to 3,4-dihydro-2(2H)-methylbenzopyran.
Direct Evidences for the Hydrogen Bonding in Water by Polymeric Receptors Carrying Diaminotriazine
Authors: Asanuma Hiroyuki , Hishiya Takayuki , Komiyama Makoto
Published: December 2003

In homogeneous aqueous solutions, copolymers of 2-vinyl-4,6-diamino-1,3,5-triazine with acrylamide selectively bind thymine and theobromine through complementary hydrogen bonding, as confirmed by 1H-NMR and ultrafiltration experiments. The corresponding monomer is inactive, indicating the predominance of polymer effect for the recognition in water.
Uniform-sized Molecularly Imprinted Polymers for β-Estradiol
Authors: Haginaka Jun , Sanbe Haruyo
Published: December 2003

A uniform-sized molecularly imprinted polymer (MIP) for β-estradiol has been prepared using 4-vinylpyridine and ethylenedimethacrylate as a functional monomer and cross-linker, respectively. The molecular recognition properties of the MIP were evaluated by HPLC using a mixture of phosphate buffer and acetonitrile as the eluent. The MIP showed the highest selectivity for β-estradiol. The MIP could efficiently separate estrogens from other steroids such as testosterone and corticosterone, and could separate estrogens one another.
One-Pot Synthesis Using Supported Reagents System: Conversion of β-Dicarbonyl Compounds to α-Thiocyano-β-dicarbonyl Compounds Using CuBr2/Al2O3-KSCN/SiO2
Authors: Suzuki Yoshitada , Kodomari Mitsuo
Published: December 2003

Transformation of β-dicarbonyl compound 1 to α-thiocyano-β-dicarbonyl compounds 3 in one-pot was achieved by using supported reagents system CuBr2/Al2O3-KSCN/SiO2, in which 1 reacts first with CuBr2/Al2O3 and the product, α-bromo-β-dicarbonyl compound 2 reacts with KSCN/SiO2 to give the final product 3 in good yield.
Persistent Tris(t-butyldimethylsilyl)silyl Radical and Its New Generation Methods
Authors: Kira Mitsuo , Obata Takeshi , Kon Itaru , Hashimoto Hisako , Ichinohe Masaaki , Sakurai Haruaki , Kyushin Soichiro , Matsumoto Hideyuki
Published: December 2003

A persistent silyl radical, tris(t-butyldimethylsilyl)silyl radical, (t-BuMe2Si)3Si· (1), was produced by two new methods in addition to a conventional hydrogen abstraction from the corresponding hydrosilane: one-electron oxidation of (t-BuMe2Si)3SiNa (2) by NO+BF4− and one-electron reduction of (t-BuMe2Si)3SiBr (3) by sodium.
Syntheses of Novel Fullerene Tweezers and Their Supramolecular Inclusion Complex of C60
Authors: Matsubara Hiroshi , Shimura Tomohiro , Hasegawa Akio , Semba Miki , Asano Kaori , Yamamoto Koji
Published: December 2003

Fullerene tweezers which have a rigid acetylenic spacers were synthesized and their inclusion abilities for C60 were examined by UV spectroscopy. From the spectra, the association constants were determined using Benesi-Hildebrand method. Fullerene tweezers with a 1,4-bis(4-oxycarbonylphenyl)butadiyne spacer showed the highest association constant for C60 (39300 ± 250 dm3mol−1 in benzene).
Synthesis, Structure and Properties of Tetranuclear Molybdenum(I) Carbonyl Thiolate Complex with Dicarboxylate Bridging Ligand
Authors: Pan Guohua , Zhuang Botao , He Lingjie , Chen Jun , Lu Jiaxi
Published: December 2003

A novel complex, [Bu4N]2[{Mo2(μ-SPh)2(CO)6}2(η2-μ-O2C(CH2)2CO2-μ-η2)] 1, is synthesized by the reaction of [Bu4N][Mo2(μ-SPh)2(μ-Br)(CO)6] and butanedioic in the present of Et3N in acetone. X-ray crystal structure of 1 is determined. 1 might possess an electrochemistry character of four-electron reduction in a single step.
The Lamellar Repeat Distance of Phospholipid Bilayers in Excess H2O and D2O. A Small-Angle X-Ray Scattering Study
Authors: Kobayashi Yukihiro , Fukada Kazuhiro
Published: December 2003

The lamellar repeat distance of multilameller stack of phosphatidylcholine membranes in excess H2O and D2O was determined by small-angle x-ray scattering measurements. When the lipids are in gel-state, the repeat distances in H2O and in D2O are almost the same. When the lipids are in liquid crystalline state, on the contrary, the repeat distances in D2O decrease by ca. 1 Å compared with that in H2O. It is confirmed that the decrease of the repeat distance is due to the decrease of the water layer thickness.
Efficient Method for Pinacol Coupling of Aromatic and Aliphatic Ketones by Using Titanium(II) Chloride and Zinc in the Presence of Pivalonitrile
Authors: Mukaiyama Teruaki , Kagayama Akifumi , Shiina Isamu
Published: December 2003

The reductive coupling reaction of aromatic and aliphatic ketones including acyclic aliphatic ketones proceeded smoothly to give the corresponding pinacols in good to high yields below room temperature by the combined use of titanium(II) chloride and zinc in the presence of pivalonitrile. Meso-selective formation of the coupling products was observed in the cases with some acyclic aliphatic ketones.
High Photocatalytic Activity of Pure TiO2 Mesoporous Molecular Sieves for the Degradation of 2,4,6-Trichlorophenol
Authors: Dai Qing , He Nongyue , Guo Yan , Yuan Chunwei
Published: December 2003

Pure TiO2 mesoporous molecular sieves. Ti-TMS, were first synthesized using alkylphosphate surfactant with different chain length. A high photocatalytic activity for the degradation of pollutant over these materials was first presented here. The Preliminary results are reported of an investigation into the photodegradation of 2,4,6-trichlorophenol, TCP, in the presence of suspended Ti-TMS solution, compared with TiO2 nanoparticles under the same conditions.
Formation and Hydrogenation of the Nitrogen Stored in Iron-based Intermetallic Compounds
Authors: Machida Ken-ichi , Ito Masahiro , Hirose Kazuhiro , Adachi Gin-ya
Published: December 2003

From a study on nitrogenation and hydrogenation characteristics of Laves phase-type intermetallic compound (TiFe2) and its surface modified composite (Ru/Al2O3/TiFe2), nitrogen molecule was found to be converted to ammonia via formation of TiFe2Nx at ambient pressure.
Photooxidation of Propene by Molecular Oxygen over FSM-16
Authors: Yoshida Hisao , Murata Chizu , Inaki Yoshitaka , Hattori Tadashi
Published: December 2003

Mesoporous silica (FSM-16) was found to exhibit a much higher activity for propene photooxidation than amorphous silica and to give different products distribution from those on silica, thus proposing FSM-16 as a new type of photooxidation catalyst.
Reversible Fluorescence Intensity Change of a Diarylethene
Authors: Takeshita Michinori , Irie Masahiro
Published: December 2003

A photochromic diarylethene 1 reversibly changed the fluorescence intensity by alternate irradiation with 330 ± 30 nm and > 460 nm light.
Enantioselective Borohydride 1,4-Reduction of α, β-Unsaturated Carboxamides Using Optically Active Cobalt(II) Complex Catalysts
Authors: Yamada Tohru , Ohtsuka Yuhki , Ikeno Taketo
Published: December 2003

The enantioselective borohydride reduction catalyzed by cobalt(II) complex was successfully applied to 1,4-reduction of β,β-disubstituted α,β-unsaturated carboxamides. In the presence of less than 1 mol% of optically active aldiminato cobalt(II) complex catalyst, the corresponding carboxamides were obtained in high yields with high enantiomeric excesses.
Chiral Zirconium-Catalyzed Asymmetric Mannich-Type Reactions Using Acylhydrazones as Imine Equivalents
Authors: Kobayashi Shu , Hasegawa Yoshiki , Ishitani Haruro
Published: December 2003

In the presence of a catalytic amount of a new zirconium catalyst, prepared from zirconium(IV) t-butoxide and (R)-3,3′-dibromo-1,1′-bi-2-naphthol, 4-trifluoromethylbenzoylhydrazones reacted with silyl enolates to afford the corresponding adducts, β-N′-acylhydrazinocarbonyl compounds, in good yields with high enantiomeric excesses. Reductive cleavage of the nitrogen-nitrogen bond of the hydrazino compound using samarium diiodide gave a chiral β-aminocarbonyl compound. In addition, the hydrazino compound was also successfully converted to chiral β-lactam and pyrazolidinone derivatives.
Synthesis of μ-Oxo Complexes of Group 4 Bridged-Metallocenes: A Convenient Separation of meso and racemo Isomers
Authors: Koyama Mina , Kimura Keisuke , Nakano Masato , Yamazaki Hiroshi
Published: December 2003

Treatment of a 1:1 mixture of meso and racemo isomers of the group 4 bridged-metallocene dichlorides, R2A(R′nC5H4−n)2MCl2 (R2 = Me2, (CH2)4; A = Si, Ge; R′ = Me, t-Bu; M = Zr, Hf; n = 1-3) with 0.5 equivalent of amine afforded an μ-oxo complex arising from the meso isomer and left the racemo isomer intact, providing a convenient method of separation of the isomeric mixture.
Picosecond Transient Infrared Spectrum of Electronically Excited trans-Stilbene in Acetonitrile and Excited Molecular Structure
Authors: Okamoto Hiromi
Published: December 2003

The picosecond transient infrared spectrum of the lowest excited singlet (S1) state of trans-stilbene in an acetonitrile solution has been recorded in the fingerprint region. Several absorption bands (absorption coefficients ε ≤ 100) attributable to in-plane vibrations of the S1 species have been observed. A minor contribution of a polarized structure to the S1 state is suggested.
Direct Hydrogenation of Carboxylic Acids to Corresponding Aldehydes Catalyzed by Palladium Complexes in the Presence of Pivalic Anhydride
Authors: Nagayama Kazuhiro , Shimizu Isao , Yamamoto Akio
Published: December 2003

Carboxylic acids are catalytically hydrogenated into corresponding aldehydes by palladium complexes in the presence of pivalic (trimethylacetic) anhydride under H2. Less hindered aliphatic and aromatic acids are reduced to aldehydes in high yields. The method is also applicable to hydrogenation of dibasic carboxylic acids and carboxylic acids containing heterocyclic groups.
Effect of Formyl Group on Photoinduced Hydrogen Atom Transfer and cis-trans Isomerization of 2[2-(2-Pyrrolyl)ethenyl]pyridine
Authors: Arai Tatsuo , Hozumi Yasutomo
Published: December 2003

Formyl group as a substituent enhanced the hydrogen atom transfer in the excited singlet state as well as the intersystem crossing from the singlet to the triplet excited state of 2[2-(2-pyrrolyl)ethenyl]pyridine.
Synthesis of 4-Hydroxy-2-cyclopentenone Derivatives by [3 + 2] Annulation of β-Heteroatom-Substituted Acryloylsilanes and Lithium Enolate of Methyl Ketones
Authors: Takeda Kei , Ohtani Yasuhiro , Ando Emi , Fujimoto Ken-ichi , Yoshii Eiichi , Koizumi Toru
Published: December 2003

The [3 + 2] annulation using β-[2-(pyridyl)thio] and β,β-dichloro derivatives of acryloylsilane and the lithium enolate of methyl ketones successfully proceeded to afford 4-alkyl-4-hydroxy-3-(2-pyridylthio)cyclopentanone and 4-alkyl-3-chloro-4-hydroxy-2-cyclopentenone, respectively.
Molecular Assembling of π-Conjugated Poly(pyrimido[5,4-d]pyrimidine-2,6-diyl)s Prepared by Organometallic Polycondensation
Authors: Yamamoto Takakazu , Lee Bang-Lin
Published: December 2003

π-conjugated poly(pyrimido[5,4-d]pyrimidine-2,6-diyl)s prepared by an organometallic polycondensation and having long side chains are considered to take an end-to-end type packing in the solid as judged from their X-ray diffraction patterns. Their UV-visible spectra show a main absorption peak at about 450 nm, supporting the presence of an expanded π-conjugation system.
Ordering of Dipeptide Molecules on Guanidinium Bilayer Membrane
Authors: Watanabe Eiji , Kunitake Toyoki
Published: December 2003

Dipeptide molecules were shown by induced circular dichrosim to bind in specific manners on guanidinium-functionalized bilayer membranes in 40 vol% ethanol/water. The carboxylate-guanidinium interaction determined the peptide alignment.
Effect of Cation Content of Polycation-type Gene Carriers on in vitro Gene Transfer
Authors: Yamaoka Tetsuji , Hamada Nobuhito , Iwata Hiroo , Murakami Akira , Kimura Yoshiharu
Published: December 2003

Dextran-based polycations having different cation structures and contents were evaluated as carriers for transferring genes to mammalian cells in vitro. 2-(N,N-Dimethylamino)ethyl dextran having tertiary-amine-type cations induced very high transient gene expression in the COS-1 cells, while 2-aminoethyl dextran having primary-amine-type cations did not induced it at all. The cation content of the former was also found to affect the transient gene expression and the cytotoxicity of the polycations.
Heterodinuclear Complex Cp*Ru(CO)2Co(CO)4 (Cp* = η5–C5Me5) Induced Selective Dimerization of Terminal Alkynes
Authors: Matsuzaka Hiroyuki , Ichikawa Koji , Ishii Tomohiko , Kondo Mitsuru , Kitagawa Susumu
Published: December 2003

A heterobimetallic complex Cp*Ru(CO)2Co(CO)4 1 (Cp* = η5–C5Me5) and its selective reactions with alkynes are reported. Stoichiometric head-to-tail dimerization of tolylacetylene affords the dinuclear metallacyclopentadiene complex Cp*(CO)Ru{η2:η4–μ2–C(Tol)CHC(Tol)CH}Co(CO)2 2 whereas catalytic head-to-head coupling of methylpropiolate yields (E)-(MeO2C)CH=CH(C≡CCO2Me) 3. The structure of 2 has been determined by X-ray crystallography.
Solvolysis of β,β-Dialkylvinyliodonium Salt: Primary Vinyl Cation Intermediate and Alkyl Participation
Authors: Okuyama Tadashi , Sato Koichi , Ochiai Masahito
Published: December 2003

Solvolysis of both E and Z isomers of a β,β-dialkylvinyl(phenyl)iodonium salt gave extensively rearranged products. A mechanism involving a primary vinyl cation intermediate as well as the alkyl participation leading to secondary vinyl cations is proposed.
A Preferable Probe Molecule for Evaluating the Surface Acidic Properties of Sulfated Zirconium and Iron Oxides by Microcalorimetric Adsorption Measurement
Authors: Han Yuwang , Zou Hu , Shen Jianyi , Ji Weijie , Chen Yi
Published: December 2003

Microcalorimetric adsorption of dimethyl ether as well as ammonia on sulfated zirconium and iron oxides indicated that the former is a preferable probe molecule to evaluate surface acid strength of this kind of strong solid acids.
Formation of Cu Nanoparticles from CuO Powder by Laser Ablation in 2-Propanol
Authors: Yeh Ya-Huey , Yeh Ming-Shin , Lee Yi-Pei , Yeh Chen-Sheng
Published: December 2003

Laser ablation technique has been employed to generate Cu nanoparticles from CuO powder in 2-propanol. The resulting copper colloids are conspicuously stable under aerobic and protective agent-free conditions. Larger particles have also been produced through the photoinduced aggregation.
Photo-Induced Reaction Dynamics in Poly(di-n-hexylsilylene) by Excimer Laser Flash Photolysis
Authors: Seki Shu , Tsuji Shou , Nishida Kazutaka , Matsui Yoshinori , Yoshida Yoichi , Tagawa Seiichi
Published: December 2003

KrF excimer laser induced photo-dissociation reaction was observed for poly(di-n-hexylsilylene) (PDHS) in several solvents at room temperature by using transient absorption spectroscopy technique within the wavelength range at 340-1600 nm. Transient absorption strongly depended on solvents suggesting that observed near UV absorption was ascribed to polysilylated silyl radicals in cyclohexane and tetrahydrofran (THF), and electron photoejection was also observed in CH2Cl2 giving radical cations of PDHS.
Oxidation of 2-Chlorophenol Effected by Na+ and CuO/Zeolites in Supercritical Water
Authors: Lin Kuen-Song , Wang H Paul , Yang Y W
Published: December 2003

Supercritical water oxidation (SCWO) of 2-chlorophenol (2CP) is very effected in the presence of 0.02 M Na+ that reduces the formation of by-products (higher chlorinated phenols). The undesired by-products in the SCWO of 2CP catalyzed by CuO in zeolites Y, ZSM-5, and ZSM-48 is also reduced extensively. Chlorine-bonded CuO species in the channels of ZSM-5 are not observed by EXAFS (extended X-ray adsorption fine structure) spectroscopy.
Effective Catalysts for Conversion of Methane to Ethane and Ethylene Using Carbon Dioxide
Authors: Wang Ye , Takahashi Yoshimoto , Ohtsuka Yasuo
Published: December 2003

The combination of CaO with Cr2O3 leads to active catalysts for selective conversion of methane to ethane and ethylene by carbon dioxide in the absence of oxygen.
Dip-Coated Ru-Mo-O/Ti Electrodes for Electrochemical Capacitors
Authors: Takasu Yoshio , Nakamura Takashi , Murakami Yasushi
Published: December 2003

RuO2-MoO3/Ti clectrodes prepared by a dip-coating method provide an extremely large pseudocapacitance showing that they have a potential for use as electrochemical capacitors. The highest pseudocapacitance was 208 F g−1 for RuO2(50)-MoO3(50)/Ti. The voltammetric charge of this electrode, 166 C g−1 between 0.3 and 1.1 V (vs. RHE), corresponds to 0.48 protons contributed to the adsorption and desorption on every loaded ruthenium, if the probable contribution of molybdenum to the pseudocapacitance was neglected.
Dinuclear Pyridine-1-Imine-Bridged Rhodium(III) Complexes. Intramolecular Carbon-Hydrogen Bond Activation
Authors: Retbøll Mikael , Ishii Youichi , Hidai Masanobu
Published: December 2003

Novel dinuclear pyridine-1-imine Rh(III) complexes [Cp*Rh(μ2-Cl){μ2-NHNC5H4(4-Me)}2RhCp*]Cl[PF6]2 (3) and [Cp*Rh(μ2-Cl){μ2-NHNC5H3(2-CH2)(6-Me)}RhCl-Cp*][PF6](4) were synthesized by the reaction of [Cp*RhCl2]2 with [NH2NC5H4(4-Me)][PF6] and [NH2NC5H3(2,6-Me2)][PF6], repectively, in the presence of a base. The formation of 4 involves C(sp3)-H bond activation at the benzylic position of a pyridine-1-imine ligand.
Construction of Monolayers and Langmuir-Blodgett Films of a Fullerene-Bearing Artificial Lipid
Authors: Nakanishi Takashi , Murakami Hiroto , Nakashima Naotoshi
Published: December 2003

A C60-bearing artificial lipid 1 forms stable monolayers at the air-water interface both in the dark and in the light. The Langmuir-Blodgett (LB) film prepared in the dark showed a phase transition by which the electronic interaction between the fullerene moieties was controllable. The LB film prepared in the light exhibited structureless electronic spectra with almost no temperature dependence.
Synthesis and Electrochemical Behavior of a New Water Soluble Ca2+-selective Ionophore Based on Calix[4]arene-triacid-monoquinone
Authors: Chung Taek Dong , Kang Sun Kil , Kim Hasuck , Kim Joo Ryun , Oh Weon Seok , Chang Suk-Kyu
Published: December 2003

A new water-soluble calix[4]arene-triacid-monoquinone 3 has been synthesized and its ion binding properties in aqueous solution were investigated by means of voltammetry and UV-visible spectrophotometry. The electrochemical behavior of 3 is dependent on the concentration of Ca2+ ion rather than that of other alkaline earth metal ions as well as alkali metal cations. The selective response toward Ca2+ was achieved even in the presence of a large excess ( > 1000-fold) of interfering Na+ ion.
A New Approach for Chiral Allyl Amines via a Novel Dichloromethylenation of Oxazolidinones
Authors: Reddy G Vidyasagar , Iyengar D S
Published: December 2003

A novel dichloromethylenation of oxazolidinones and their conversion to allyl amines 3a-e, key precursors for potential HIV protease inhibitors is described.
Giant Circular Motion of Zinc Particles in Sulfuric Acid under High Magnetic Field
Authors: Shinohara Kenji , Aogaki Ryoichi
Published: December 2003

Under high magnetic field, giant circular motion of zinc particles during dissolution in sulfuric acid was observed. This effect was ascribed to the Lorentz force arising from the interaction between the dissolution current penetrating through the inside of the particle and the external magnetic field. According to theoretical predictions, it wasd concluded that the coagulated zinc particles take the circular motion, and the particle velocity is proportional to the magnetic flux density.
Intercalation of Methanol and Ethanol into Na-Fluorotetrasilicic Mica: Difference in Formation of Single and Double Layer Intercalates
Authors: Kubo Jun , Mori Tohru , Morikawa Yutaka
Published: December 2003

Intercalation of methanol and ethanol into Na-fluorotetrasilicic mica was traced dynamically by X-ray diffraction. The intercalation of methanol is much faster than that of ethanol. Methanol forms successively single and double layers between silicate sheets of the mica, while ethanol forms similar layers concurrently.
Direct Monitoring of Respiratory Activity of Cultured Cells by Potential-step Chronoamperometry
Authors: Ueda Takehiko , Kato Eiichi , Oshikawa Kiminori , Arai Junichiro , Sunamoto Junzo
Published: December 2003

A new method to determine oxygen uptake rate of living cells is described. Two kinds of cultured mammalian cells were incubated in a 2.0 ml vol cuvette, which was equipped with an oxygen electrode as specially designed to measure the oxygen concentration ([O2]) in the culture medium. This new method allowed 1) instant determination of the respiratory activity of living cells, and 2) simultaneous monitoring of responses of cell against extracellular stimuli.
Color Bands in Methacrylic Acid Polymerization
Authors: Srivastava Prem Kumar , Majhi Shyam Sundar , Rastogi Raghunath Prasad , Hanazaki Ichiro
Published: December 2003

White and pink alternating bands have been found to be formed in the polymerization of methacrylic acid in methanol in the presence of benzoyl peroxide and N,N-dimethylaniline in a glass tube. The band structure depends on the initial concentrations of methanol and benzoyl peroxide.
Generation of Visible Light Response on the Photocatalyst of a Copper Ion Containing TiO2
Authors: Sakata Yoshihisa , Yamamoto Tomonori , Okazaki Taichi , Imamura Hayao , Tsuchiya Susumu
Published: December 2003

The generation of photocatalytic activity under the irradiation of visible light (longer than 460 nm) was observed over copper ion containing TiO2. It is suggested that low valent copper oxide which was produced in the catalyst under the irradiation of UV plays an important role to the generation of the activity under the irradiation of visible light.
Isomerization of Imines Catalyzed by Ruthenium-Hydride Complexes
Authors: Yamagishi Takamichi , Mizushima Eiichiro , Sato Hideyuki , Yamaguchi Motowo
Published: December 2003

Imine isomerization via [1,3]-hydrogen shift catalyzed by dihydrido(dinitrogen)tris(triphenylphosphine)ruthenium(II) or dihydridotetrakis(triphenylphosphine)ruthenium(II) complexes is described. In toluene under hydrogen atmosphere, ruthenium-dihydride complexes could cause the isomerization of ketimines to aldimines effectively.
A Substrate Specific Chiral Modifier Activation on Enantio-differentiating Hydrogenation over Tartaric Acid-Modified Raney Nickel
Authors: Nakagawa Satoshi , Sugimura Takashi , Tai Akira
Published: December 2003

A comparative study of the reactivities of the hydrogenation of β-ketoesters over tartaric acid-modified and unmodified Raney nickels indicated that a substrate specific activation by the tartaric acid modification is the reason for the almost perfect enantio-differentiation in the reaction of methyl 3-cyclopropyl-3-oxopropanoate (4).
Synthesis of Liquid-Crystalline Enynes by Palladium-Catalyzed Cross-Coupling Reaction
Authors: Kitamura Tsugio , Aoyagi Yasutaka , Fujiwara Yuzo
Published: December 2003

An arylvinyl bromide bearing a long-chain alkoxy group reacts with arylacetylenes in the presence of a palladium catalyst to give liquid-crystalline 1,4-diaryl-1-buten-3-yne derivatives. The new liquid-crystalline compounds with a conjugated enyne core show mesogenic phases at a wide range of temperature.
A Molecular Structure of Bis(N-octylethylenediamine)zinc(II) Nitrate in Crystal and the Aggregations in Wet Chloroform and Benzene Solutions
Authors: Iida Masayasu , Tanase Tomoaki , Asaoka Norie , Nakanishi Akiko
Published: December 2003

Zinc complex with N-octylethylenediamine( = OE), Zn(OE)2(NO3)2, was prepared and its molecular structure was determined on the basis of an X-ray crystallographic analysis. It was revealed that in the octahedral molecular structure the nitrato groups are trans and the octyl chains are transoid. Extensive aggregations of this complex in wet chloroform and wet benzene systems were also studied using 1H NMR self-diffusions for the solvents and the zinc complex.
Direct Synthesis of the Novel 2-D Mixed-ligands Lead(II) Complex, Crystal Structure of [Pb(4,4′-bpy)(NO3)(SCN)]n (4,4′-bpy = 4,4′-bipyridine): (A New Polymeric Compound with Three Bridged Ligand and Inactive Lone Pair)
Authors: Morsali A , Mahjoub A R
Published: December 2003

A lead(II) complex with three ligands, 4,4′-bipyridine (4,4′-bpy), nitrate, and thiocyanate, has been synthesized and characterized by CHN elemental analysis, IR-, 1H-, 13C- and 207Pb NMR spectroscopy. The single-crystal X-ray data of [Pb(4,4′-bpy)(NO3)(SCN)]n compound shows that the complex to be two dimensional polymeric and the Pb atom has an eight-coordinate geometry. The lone pair of electrons on lead(II) is inactive in this complex.
Synthesis and Reactivity of Bucky Ruthenocene Ru(η5-C60Me5)(η5-C5H5)
Authors: Matsuo Yutaka , Kuninobu Yoichiro , Ito Shingo , Nakamura Eiichi
Published: December 2003

Metathetical coupling of an η5-fullerene ruthenium complex Ru(η5-C60Me5)Cl(CO)2 and sodium cyclopentadienide gives a molecular hybrid of ruthenocene and fullerene, Ru(η5-C60Me5)(η5-C5H5) (bucky ruthenocene), the structure of which was determined by spectroscopic and crystallographic analyses. The molecule shows unique reactivity among known ferrocene and ruthenocene compounds.