bluuebunny/crossref_metadata_2025_split huggingface dataset:
Context-dependent changes in strength and efficacy of leg coordination mechanisms
Authors: Dürr Volker 
Published: June 2005

SUMMARYAppropriate coordination of stepping in adjacent legs is crucial for stable walking. Several leg coordination rules have been derived from behavioural experiments on walking insects, some of which also apply to arthropods with more than six legs and to four-legged walking vertebrates. Three of these rules affect the timing of stance–swing transition [rules 1 to 3(sensu Cruse)]. They can give rise to normal leg coordination and adaptive responses to disturbances, as shown by kinematic simulations and dynamic hardware tests. In spite of their importance to the study of animal walking, the coupling strength associated with these rules has never been measured experimentally. Generally coupling strength of the underlying mechanisms has been considered constant rather than context-dependent.The present study analyses stepping patterns of the stick insect Carausius morosus during straight and curve walking sequences. To infer strength and efficacy of coupling between pairs of sender and receiver legs, the likelihood of the receiver leg being in swing is determined, given a certain delay relative to the time of a swing–stance (or stance–swing) transition in the sender leg. This is compared to a corresponding measure for independent, hence uncoupled, step sequences. The difference is defined as coupling strength. The ratio of coupling strength and its theoretical maximum is defined as efficacy.Irrespective of the coordination rule, coupling strength between ipsilateral leg pairs is at least twice that of contralateral leg pairs, being strongest between ipsilateral hind and middle legs and weakest between contralateral middle legs. Efficacy is highest for inhibitory rule 1, reaching 84–95% for ipsilateral and 29–65% for contralateral leg pairs. Efficacy of excitatory rules 2 and 3 ranges between 35–56% for ipsilateral and 8–21% for contralateral leg pairs. The behavioural transition from straight to curve walking is associated with context-dependent changes in coupling strength, increasing in both outer leg pairs and decreasing between inner hind and middle leg. Thus, the coordination rules that are thought to underlie many adaptive properties of the walking system,themselves adapt in a context-dependent manner.
Regulation of stroke and glide in a foot-propelled avian diver
Authors: Watanuki Yutaka , Takahashi Akinori , Daunt Francis , Wanless Sarah , Harris Mike , Sato Katsufumi , Naito Yasuhiko 
Published: June 2005

SUMMARYBottom-feeding, breath-hold divers would be expected to minimize transit time between the surface and foraging depth, thus maximizing the opportunities for prey capture during the bottom phase of the dive. To achieve this they can potentially adjust a variety of dive parameters, including dive angle and swim speed. However, because of predictable changes in buoyancy with depth,individuals would also be expected to adjust dive behavior according to dive depth. To test these predictions we deployed miniature, dorsally attached data-loggers that recorded surge and heave accelerations at 64 Hz to obtain the first detailed measurements of a foot-propelled diving bird, the European shag Phalacrocorax aristotelis, in the wild. The results were used to investigate biomechanical changes during the descent, ascent and bottom phases for dives varying between 7 m and 43 m deep. Shags descended and ascended almost vertically (60–90° relative to the sea surface). During descent, swim speed varied between 1.2–1.8 m s–1 and the frequency of the foot stroke used for propulsion decreased significantly with depth, mainly due to a fivefold increase in the duration of the glide between strokes. Birds appeared to maintain the duration and the maximum strength of power stroke and thus optimize muscle contraction efficiency.
Effect of an increase in gravity on the power output and the rebound of the body in human running
Authors: Cavagna G. A. , Heglund N. C. , Willems P. A. 
Published: June 2005

SUMMARYThe effect of an increase in gravity on the mechanics of running has been studied by using a force platform fixed to the floor of an aircraft undergoing flight profiles, resulting in a simulated gravity of 1.3 g. The power spent to maintain the motion of the centre of mass of the body is ∼1.3 times greater than on Earth, due to a similar increase of both the power spent against gravity and to sustain the forward speed changes. This indicates that the average vertical displacement per unit distance and the average direction of the push are unchanged. The increase in power is mainly due to an increase in step frequency rather than to an increase in the work done at each step. The increase in step frequency in turn is mainly due to a decreased duration of the effective aerial phase (when the vertical force is less than body weight), rather than an increase in the stiffness of the bouncing system. The maximal speed where step frequency can match the resonant frequency of the bouncing system is increased by ∼5 km h–1 at 1.3 g. These results suggest a similar running mechanics at higher gravity, maintained at the expense of greater energy expenditure.
Photochemical Reaction Mechanism of 2,2′-Pyridil in Alcoholic Media
Authors: Yamada Naoki , Hasegawa Miki , Kumagai Ken-ichi , Enomoto Shigendo , Horiuchi Hiroaki , Yoshinaga Tetsutaro , Hiratsuka Hiroshi , Kobayashi Michio , Hoshi Toshihiko 
Published: June 2005

Abstract
Time-resolved transient absorption spectra of photo-irradiated 2,2′-pyridil were measured in PVA films. The broad bands at 552 and ∼455 nm, appearing just after photo-excitation of 2,2′-pyridil, are assigned to the skewed triplet species. The triplet species changes into 1-hydroxy-2-oxo-1,2-di(2-pyridyl)ethyl (pyridoil) radical via the abstraction of a hydrogen atom from the solvent. The radical produced by the photo-irradiation of 2,2′-pyridil is confirmed to be the pyridoil radical from the measurement of the polarized absorption spectrum, with the aid of the stretched polymer film technique and MO calculations. The time-resolved transient absorption spectra of 2,2′-pyridil irradiated by a xenon flash lamp in a 1:1 (v/v) mixed solvent of methanol and ethanol show that the pyridoil radical further abstracts a hydrogen atom from the solvent to afford cis-enediol (cis-1,2-di(2-pyridyl)-1,2-ethenediol) and that cis-enediol is converted into trans-enediol (trans-1,2-di(2-pyridyl)-1,2-ethenediol). 2,2′-Pyridil shows a structured Tn ← T1 absorption spectrum in a 1:1 (v/v) mixed solvent of methylcyclohexane and 2-methylbutane, indicating that 2,2′-pyridil takes a planar structure in the lowest triplet excited state in a nonpolar medium.
Synthesis and Redox Behavior of Dicobalt Complexes Having Flexible and Rigid Linkers
Authors: Shimakoshi Hisashi , Hirose Satoshi , Ohba Masaaki , Shiga Takuya , Okawa Hisashi , Hisaeda Yoshio 
Published: June 2005

Abstract
New dicobalt complexes, [CoII2L], with Schiff-base ligands (L1–L4) having two discrete metal chelating sites, which are connected to each other by flexible and rigid linkers, have been synthesized. The complexes were characterized by IR, UV–vis, and mass spectroscopy as well as elemental analyses. A magnetic study indicates an antiferromagnetic interaction in 4. The redox behavior of the complexes was examined by means of cyclic voltammetry compared with those of the corresponding mononuclear complexes. Redox waves, identified to CoIII/CoII and CoII/CoI, were clearly observed. Electro-generated [CoI2L]2− reacts with alkyl halide at each metal center to give an organocobalt complex.
Preparation of Monometallic Complexes of Non-Macrocyclic Ligands
Authors: Niazi Rahnama Ahmad , Golchoubian Hamid , Pritchard Robin 
Published: June 2005

Abstract
Dicompartmental non-macrocyclic ligands containing six (N4O2) and four (N2O2) coordination atoms were prepared. The ligands were constructed in order to investigate the effect of an opened four-coordination site (non-marcocyclic effect) on the geometrical structure of a complex in a six-coordination site with a labile metal. In this regard, monometallic non-macrocyclic complexes of Zn(II), Co(II), and Co(III) were prepared and characterized. The preparation of a Co(III) complex through two different routes, and also the X-ray crystal structure of a Zn(II) complex demonstrated that the structures of the complexes were intact even in the presence of two bulky phenyl groups in four-coordination site. The characterization of the prepared complexes confirmed the presence of two protons in the four-coordination site of diimine complexes and a lack of them in diamine complexes.
Hybrid Organic–Inorganic Conductor Coupled with BEDT-TTF and Photochromic Nitrosyl Ruthenium Complex
Authors: Okubo Masashi , Enomoto Masaya , Koyama Kazuko , Uwatoko Yoshiya , Kojima Norimichi 
Published: June 2005

Abstract
An organic–inorganic hybrid system coupled with an organic conductor and photosensitive transition metal complex has a possibility to exhibit fascinating multifunctionalities, such as photo-controllable conductor. To explore multifunctional materials, such as a photo-tunable conductor, we prepared (BEDT-TTF)4[RuCl5(NO)]·C6H5CN (BEDT-TTF: 4,5-bis(ethylenedithio)tetrathiafulvalene) by electrocrystallization, and investigated the structural and physical properties. X-ray crystallographic analysis shows alternate layers of BEDT-TTF cations and ruthenium complex anions. The organic layer is formed by the dimers of BEDT-TTF arranged almost perpendicular to each other, which indicates that the donor arrangement of this salt belongs to κ-type. Based on the Raman spectrum, the oxidation state of the BEDT-TTF molecules is estimated to be +0.7. X-ray structural analysis and the EPR spectra suggest that there is a partial electron transfer from BEDT-TTF to the π* orbital of NO ligand in [RuCl5(NO)] through a short intermolecular contact. A magnetic susceptibility measurement and the EPR spectra proved this compound to be a localized spin system due to a strong on-site Coulomb repulsion, which results in the semiconducting behavior of this compound.
Dinuclear Mn(II), Ni(II), and Zn(II) Complexes Bridged by Bis(p-nitrophenyl) Phosphate Ion: Relevance to Bimetallic Phosphodiesterase
Authors: Shiraishi Hitomi , Jikido Reiko , Matsufuji Kanako , Nakanishi Tatsuaki , Shiga Takuya , Ohba Masaaki , Sakai Ken , Kitagawa Hiroshi , Okawa Hisashi 
Published: June 2005

Abstract
2,6-Bis[N,N-di(2-pyridylmethyl)aminomethyl]-4-methylphenol (Hbpmp) has afforded dinuclear Mn(II), Ni(II), and Zn(II) complexes with two bis(p-nitrophenyl) phosphate (BNP−) ions, [M2(bpmp)(bnp)2]ClO4 (M = Mn (1), Ni (2), Zn (3)). The structure of 1·2MeCN has been determined by the single crystal X-ray method. It has a dinuclear core structure bridged by the phenolic oxygen atom of bpmp− and two BNP− ions. Each metal center has a pseudo octahedral geometry with an average Mn-to-donor bond distance of 2.207 Å. Physicochemical properties of 1–3 are studied and their relevance to biological phosphodiesterase is discussed.
cis-trans-cis-Tetrabromotetramethylcyclotetrasiloxane: a Versatile Precursor of Ladder Silsesquioxanes
Authors: Unno Masafumi , Chang Shengho , Matsumoto Hideyuki 
Published: June 2005

Abstract
The title compound was isolated for the first time by a novel procedure including dephenylbromination of cyclotetrasiloxane. The stereostructure of the tetrabromide was confirmed by condensation with diphenylsilanediol, affording anti-tricyclo[7.3.1.13,7]hexasiloxane. This tetrabromide spontaneously decomposed in air to afford a white powder insoluble in organic solvents. Measurements of the TG, IR, and solid-state NMR spectra of the product revealed that a ladder polysilsesquioxane with high thermal stability and stereoregularity was obtained.
The Electronic Effects of Bulky Aryl Substituents on Low Coordinated Phosphorus Atoms in Diphosphenes and Phosphaalkenes by Functionalization at the Para Position
Authors: Kawasaki Subaru , Nakamura Akitake , Toyota Kozo , Yoshifuji Masaaki 
Published: June 2005

Abstract
The electronic effects of bulky aryl substituents on low coordinated phosphorus atom(s) in diphosphenes and phosphaalkenes have been examined by means of functionalization at the para position of the substituents. Bulky bromobenzenes bearing an electron-donating or electron-withdrawing group at the para position were prepared as precursors of the substituents and some of them were applied to preparations of the corresponding diphosphenes and fluorenylidene(phenyl)phosphines bearing low-coordinated phosphorus atom(s). Electronic perturbation by the para-substituent in the system was indicated by UV–vis spectra and 31P NMR chemical shifts. These observations can be attributed to effects induced by electronic properties of the bulky aryl substituent(s) on the lone pair of the low-coordinated phosphorus atom.
Reaction of Ketone Hydrazones with Diselenium Dihalides: Simple Synthesis of Δ3-1,3,4-Selenadiazolines and 2,5-Diarylselenophenes
Authors: Okuma Kentaro , Izaki Toshiharu , Kubo Kento , Shioji Kosei , Yokomori Yoshinobu 
Published: June 2005

Abstract
Sterically congested cis- and trans-Δ3-1,3,4-selenadiazolines were isolated by one-pot reactions of ketone hydrazones with diselenium dibromide, which suggested the in situ formation of selone and diazoalkane intermediates. The thermolysis of these compounds gave symmetrical olefins, whereas oxidation afforded the corresponding azines. The reaction of acetophenone hydrazones with diselenium dibromide afforded 2,5-diarylselenophenes in moderate yields. The reaction proceeded through selone intermediates.
Photoisomerization and Photoinduced Hydrogen-Atom Transfer in 1-Chloro-4-(2-pyrrol-2-ylethenyl)phthalazine
Authors: Akiu Kei , Saijo Masako , Ikegami Masashi , Arai Tatsuo 
Published: June 2005

Abstract
An olefin having a phthalazine ring and a pyrrole ring (2) exhibited a fluorescence spectrum with a large Stokes shift in the cis-isomer. The cis-isomer composition at the photostationary state was considerably high, so as give an isomer ratio at the photostationary state ([cis]/[trans])PSS of 97/3 upon irradiation at 366 nm. These results indicate the occurrence of intramolecular hydrogen-atom transfer in the singlet excited state. The produced tautomer scarcely gave the trans isomer by a reverse hydrogen-atom transfer, and cis-to-trans isomerization was prevented by the existence of intramolecular hydrogen bonding in the cis isomer. Both cis-2 and trans-2 underwent intersystem crossing to give the same triplet excited state with a lifetime of 10 μs in benzene. Based on these results, the photochemical isomerization of 2 in the singlet excited state and in the triplet excited state is discussed.
Metal Cation-Exchanged Montmorillonite-Catalyzed Addition of Organic Disulfides to Alkenes
Authors: Nishimura Takahiro , Yoshinaka Tomoaki , Uemura Sakae 
Published: June 2005

Abstract
The addition of organic disulfides to alkenes, giving vic-bis(alkylthio)alkanes and vic-bis(arylthio)alkanes, proceeds in chlorobenzene in the presence of a catalytic amount of a variety of metal cation-exchanged montmorillonites (abbreviated as Mn+-monts), Al3+, Fe3+, Zr4+, and In3+ being effective as Mn+. The most effective Fe3+-mont can be reused for the addition of diphenyl disulfide to cyclohexene at least 8 times without an appreciable loss of catalytic activity.
Photochromism of Diarylethene Maleimide Derivatives
Authors: Yamaguchi Tadatsugu , Matsuo Masatsugu , Irie Masahiro 
Published: June 2005

Abstract
Diarylmaleimide derivatives having an indole ring, N-cyanomethyl-2-[2-methoxy-1-benzothiophen-3-yl]-3-[2-methyl-1-octadecylindol-3-yl]maleimide or N-cyanomethyl-2-[2-ethoxy-1-benzothiophen-3-yl]-3-[2-methyl-1-octadecylindol-3-yl]maleimide, were synthesized in an attempt to shift the photosensitive wavelength longer such that it becomes longer than 450 nm. The derivatives underwent the photocyclization reaction upon irradiation with 450–550 nm light in hexane solution and the photogenerated closed-ring isomers returned to the initial open-ring isomers upon irradiation with light longer than 600 nm.
Growth of Nanoporous Silica Spherical Particles by the Stöber Method Combined with Supramolecular Templating Approach
Authors: Shimura Naoki , Ogawa Makoto 
Published: June 2005

Abstract
Nanoporous silica spherical particles with narrow particle size distributions (standard deviation: 0.03–0.22) were synthesized by the Stöber method combined with supramolecular templating approach using tetraethoxysilane and cetyltrimethylammonium chloride. The reaction was conducted at 276 K to observe particle growth. Particles formed after the reaction for ca. 0.5 h, as shown by the fact that the solution became turbid. After the reaction for 0.5 h, particles with an average particle size of 440 nm in diameter were collected by filtration. The particles grew until the silica source was completely consumed. This took 50 h under the present reaction condition. The average particle size reached to ca. 1.8 μm at this stage. The calcined particles were porous with the surface areas of 380–1060 m2 g−1 and the pore diameter of 1.6–2.0 nm.
Development of Catalytic Enantioselective Reactions via Palladium Enolates as Key Intermediates
Authors: Sodeoka Mikiko , Hamashima Yoshitaka 
Published: June 2005

Abstract
This article describes the catalytic reactions that involve the generation of chiral palladium enolates and their reaction with various electrophiles. Two methods to generate the chiral enolates were developed using the two types of novel chiral palladium complexes: Pd aqua complexes and binuclear Pd μ-hydroxo complexes. In these processes, aqua or hydroxo ligand on palladium metal plays an important role as a nucleophile to promote the transmetallation or as a Brønsted base to abstract an acidic α-proton of the carbonyl group. Using the chiral Pd enolates as key intermediates, a highly enantioselective, catalytic aldol reaction, a Mannich-type reaction, a Michael reaction, and a fluorination reaction were developed.
Multiphoton Chemical Reactions on Liquid Beam Surfaces
Authors: Kohno Jun-ya , Mafuné Fumitaka , Kondow Tamotsu 
Published: June 2005

Abstract
In this account, we describe the dynamics of reactions induced by multiphoton excitation of solute and solvent molecules in solutions, studied by means of a liquid beam (a continuous liquid flow in a vacuum) combined with mass spectrometry. Unique reaction intermediates and products are found to be produced and ejected into the gas phase by multiphoton excitation of the molecules in the liquid beam. The reaction dynamics were elucidated by observing the reaction intermediates and products ejected into the gas phase. In particular, we refer to reactions via UV multiphoton excitation of solute molecules, such as ketal formation of phenyl ketones and reduction by solvated electrons, and those via IR multiphoton excitation of solvent molecules, such as formation of internally hot and cold molecules/clusters in the gas phase.
Synthesis of Kinetically Stabilized 1-Silanaphthalenes and Their Properties
Authors: Shinohara Akihiro , Takeda Nobuhiro , Sasamori Takahiro , Tokitoh Norihiro 
Published: June 2005

Abstract
The first kinetically stabilized 1-silanaphthalenes bearing a 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) group or a 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt) group were synthesized from the corresponding overcrowded bromosilanes by dehydrobromination using LDA (lithium diisopropylamide) in THF at −40 °C, respectively. The structures of 1-silanaphthalenes were confirmed by 1H, 13C, and 29Si NMR, UV–vis, Raman, and high-resolution mass spectroscopic analyses. These results and the NICS calculations indicated high aromaticity of the 1-silanaphthalenes. In spite of such high aromaticity, Tbt-substituted 1-silanaphthalene is thermally unstable and undergoes gradual dimerization in C6D6 solution to give the corresponding [4 + 2] dimer. By contrast, 1-silanaphthalene bearing a Bbt group on the Si atom was thermally stable even on heating in C6D6 at 120 °C. Tbt-substituted 1-silanaphthalene has high reactivity toward addition reactions at both 1,2- and 1,4-positions, giving the corresponding adducts in the reactions with H2O, MeOH, mesitonitrile oxide, benzophenone, and elemental chalcogens. Tbt-substituted 1-silanaphthalene underwent 1,4-addition reaction with CCl4 to give cis- and trans-adducts having a Cl atom on the Si atom and a CCl3 group at the 4-position.
Computational Spectroscopy of a Bichromophoric Molecule, 2-Methyl-1,2,3,4-tetrahydroisoquinoline, in Solutions
Authors: Kanamaru Nobuaki 
Published: June 2005

Abstract
An ab initio calculation of the title molecule was performed to interpret previously observed electronic spectra of the title system. Since the computation concerns the isolated molecule, possible effects of solvent molecules had to be taken into account, especially for such as Rydberg states. The S3 ← S0, S2 ← S0, and S1n ← S0 absorption bands are (re)assigned to the excited states of the Lb, La/CT, and nNσ* (3s) states, respectively. The minor S1a ← S0 absorption observed at the red area of the S1n ← S0 band in acetonitrile is reinterpreted as being a nNπ* (CT) state. Correspondingly, the π, nN, and aN fluorescence spectra are (re)ascribed to the excited states of the Lb, nNσ*, and nNπ* states, respectively. The nNσ* and nNπ* states are found to be restricted to the equatorial and axial conformers, respectively. The exceptionally long progression of the π fluorescence in hexane is interpreted as being due to the closeness of the La and Lb states.
Bright-green Upconversion Emission of Hexagonal LaF3 : Yb3+, Er3+ Nanocrystals
Authors: De Gejihu , Qin Weiping , Zhang Jisen , Zhao Dan , Zhang Jishuang 
Published: June 2005

Abstract
LaF3 : Yb3+, Er3+ nanoparticles were synthesized through a simple hydrothermal method. The nanoparticles were well-crystallized and exhibited hexagonal structure with fine morphology, as indicated by powder X-ray diffraction, electron diffraction, and transmission electron microscopy. The nanocrystals present a bright-green upconversion luminescence under the 978-nm excitation of a laser diode, which provides a promising upconversion phosphor for optoelectronic or biological applications.
Site-selective Coating of Polymer Thin Film Prepared by the Ink-jet Method on the Patterned Fluoroalkylsilane Monolayer Substrate
Authors: Morita Masamichi , Yasutake Shigekazu , Ishizuka Hirotaka , Fukai Jun , Takahara Atsushi 
Published: June 2005

Abstract
The purpose of this study is to establish the fundamental technology of site-selective coating of polymer thin film utilizing wetting contrast of patterned fluoroalkylsilane monolayer/silanol (Si–OH) surfaces. Polystyrene (PS)/xylene solution was coated on the patterned surface with wetting contrast by ink-jet method. The patterned PS ultrathin films were selectively formed on lyophilic Si–OH areas.
A Simple Route for Preparing Radiolarian-like Mesoporous Silica from Water–Diethyl Ether Binary Solvent System
Authors: Lin Haoxiang , Cui Kai , Yao Youwei , Cai Qiang , Feng Qingling , Li Hengde 
Published: June 2005

Abstract
An interesting radiolarian-like silica sphere has been prepared from a water–diethyl ether binary solvent system, which is characterized by SEM, TEM, XRD, and adsorption experiments. The results indicate its particular morphology and hierarchical structure, i.e., hollow interior and a crust wherein two types of mesopores with radial orientation are located. This silica product embodies a novel morphosynthesis involving unstable water–oil interface.