Inner-shell ionizations and satellites studied by the open-shell reference symmetry-adapted cluster/symmetry-adapted cluster configuration-interaction method

Open-shell reference version of the symmetry-adapted cluster (SAC) and SAC-configuration-interaction (CI) methods, termed open-shell reference (OR)-SAC and OR-SAC-CI methods, are developed and applied to inner-shell ionizations of CH4, NH3, H2O, and HF. The inner-shell ionization potentials and spectra calculated by the OR-SAC and OR-SAC-CI methods are in excellent agreement with the experimental data. Including both of the electron correlation and orbital relaxation is important for quantitative agreements. Timing comparisons with the SAC-CI general-R calculations that give similar high accuracies show an efficiency of the present OR-SAC and OR-SAC-CI methods.     

Photorefractive effect in ferroelectric liquid crystals

In this paper, we review recent progress of research on the photorefractive effect of ferroelectric liquid crystals. The photorefractive effect is a phenomenon that forms a dynamic hologram in a material. The interference of two laser beams in a photorefractive material establishes a refractive index grating. This phenomenon is applicable to a wide range of devices related to diffraction optics including 3D displays, optical amplification, optical tomography, novelty filters, and phase conjugate wave generators. Ferroelectric liquid crystals are considered as a candidate for practical photorefractive materials. A refractive index grating formation time of 8–10 ms and a large gain coefficient are easily obtained in photorefractive ferroelectric liquid crystals.     

High-energy 'composite' layered manganese-rich cathode materials via controlling Li2MnO3 phase activation for lithium-ion batteries

The 'composite' layered materials for lithium-ion batteries have recently attracted great attention owing to their large discharge capacities. Here, the 0.5Li(2)MnO(3)·0.5LiMn(0.42)Ni(0.42)Co(0.16)O(2)'composite' layered manganese-rich material is prepared and characterized by the synchrotron X-ray powder diffraction (SXPD). The relationship between its electrochemical performance and its 'composite' components, the Li(2)MnO(3) phase activation process during cycling and the cycle stability of this material at room temperature are elucidated based on its kinetic controlled electrochemical properties, dQ/dV curves and Raman scattering spectroscopies associated with different initial charge-discharge current densities (5 mA g(-1), 20 mA g(-1) and 50 mA g(-1)), cut-off voltages (4.6 V and 4.8 V) and cycle numbers (50 cycles and 150 cycles). Furthermore, its reaction pathways are tracked via a firstly introduced integrated compositional phase diagram of four components, Li(2)MnO(3), LiMn(0.42)Ni(0.42)Co(0.16)O(2), MO(2) (M = Mn(1-α-β)Ni(α)Co(β); 0 ≤α≤ 5/12, 0 ≤β≤ 1/6) and LiMnO(2), which turns out to be a very important guiding tool for understanding and utilizing this 'composite' material.     

Photodissociation dynamics of gaseous CpCo(CO)2 and ligand exchange reactions of CpCoH2 with C3H4, C3H6, and NH3

The photodissociation dynamics of CpCo(CO)(2) was studied in a molecular beam using photofragment translational energy spectroscopy with 157 nm photoionization detection of the metallic products. At 532 and 355 nm excitation, the dominant one-photon channel involved loss of a single CO ligand producing CpCoCO. The product angular distributions were isotropic, and a large fraction of excess energy appeared as product vibrational excitation. Production of CpCO + 2CO resulted from two-photon absorption processes. The two-photon dissociation of mixtures containing CpCo(CO)(2) and H(2) at the orifice of a pulsed nozzle was used to produce a novel 16-electron unsaturated species, CpCoH(2). Transition metal ligand exchange reactions, CpCoH(2) + L → CpCoL + H(2) (L = propyne, propene, or ammonia), were studied under single-collision conditions for the first time. In all cases, ligand exchange occurred via 18-electron association complexes with lifetimes comparable to their rotational periods. Although ligand exchange reactions were not detected from CpCoH(2) collisions with methane or propane (L = CH(4) or C(3)H(8)), a molecular beam containing CpCoCH(4) was produced by photolysis of mixtures containing CpCo(CO)(2) and CH(4).     

Fluorescence imaging of potassium ions in living cells using a fluorescent probe based on a thrombin binding aptamer-peptide conjugate

When a biotinylated FRET probe based on a peptide-thrombin binding aptamer conjugate was introduced together with streptavidin and biotinylated nuclear export signal peptide into HeLa cells, the resulting ternary complex enabled visualization of K(+) concentration changes in the cell.     

Experimental examination of vortex-sound generation in an organ pipe: A proposal of jet vortex-layer formation model

Aero-dynamical models of sound generation in an organ pipe driven by a thin jet are investigated through an experimental examination of the vortex-sound theory. An important measurement requirement (acoustic cross-flow as an irrotational potential flow reciprocating sinusoidally) from the vortex-sound theory is carefully realized when the pipe is driven with low blowing pressures of about 60 Pa (jet velocities of about 10 m/s). Particle image velocimetry (PIV) is applied to measure the jet velocity and the acoustic cross-flow velocity over the mouth area at the same phase by quickly switching the jet drive and the loudspeaker-horn drive. The vorticity of the jet flow field and the associated acoustic generation term are evaluated from the measurement data. It is recognized that the model of the “jet vortex-layer formation” is more relevant to the sound production than the vortex-shedding model. The acoustic power is dominantly generated by the flow–acoustic interaction near the edge, where the acoustic cross-flow velocity takes larger magnitudes. The acoustic generation formula on the vortex sound cannot deny the conventional acoustical volume-flow model because of the in-phase relation satisfied between the acoustic pressure at the mouth and the acoustic volume flow into the pipe. The vortex layers formed along both sides of the jet act as the source of an accelerating force (through the “acceleration unbalance”) with periodically alternating direction to oscillate the jet flow and to reinforce the acoustic cross-flow at the pipe mouth.     

Characterization of PVA and Chitosan/PVA Blends Prepared from Aqueous Solutions of Various Na2SO4 Concentrations

Uniplaner orientation of a particular crystal plane along the surface of a film was investigated for poly (vinyl alcohol) (PVA) film prepared by a coagulation bath with concentrated aqueous solution containing 100 ∼ 300g of Na₂SO₄ against 1 ℓ of water. The orientation distribution functions of the three crystallographic principal axes of the dried films were obtained by the X-ray diffraction technique. The same treatment was carried out for the films prepared by stretching biaxially of the fresh gel and then by drying the resultant fresh gel. The very high preferential orientation of the crystal chain axes and amorphous chain segments could be realized by the biaxially elongation. Accordingly, the techniques were applied to the biaxially stretching of chitosan and PVA blend films with high Young's modulus. The planer orientation of the chain axes of chitosan and PVA crystallites could be confirmed. The morphology of the film surface was estimated by measurements of contact angle and electron spectroscopy for chemical analysis. The results suggested that the admixture of chitosan decreases wet ability of the specimen and this tendency was slightly enhanced by the biaxially elongation.     

Structure and Mechanical Properties of Chitosan/Poly(Vinyl Alcohol) Blend Films

Summary: The origins of the thermal and mechanical properties of chitosan and poly(vinyl alcohol) (PVA) with inter- and intra-hydrogen bonds were investigated systematically by using X-ray, DSC, positron annihilation and viscoelastic measurements. Based on their individual properties, the characteristics of the blend films were estimated in relation to their morphology and mechanical properties as a function of chitosan content. The characteristics of the blend films were also analyzed in terms of the deviation from a simple additive rule of chitosan and PVA content. These results suggested that the miscibility of chitosan and PVA could be ensured by entanglement of the amorphous chain segments of chitosan and PVA. Further detailed analysis revealed that the chitosan content on the film surface is higher than that of the admixture content of chitosan after elongation, although the chitosan and PVA chains were crystallized independently. The elongation could be achieved for the blend films whose PVA content was higher than 50% and the drawn blend films were transparent. Thus, it may be expected that sufficiently entangled meshes formed between chitosan and PVA amorphous chains within the film, the PVA content being higher than 50%, were maintained under the elongation process.     

Synthesis of 4-acylcoumarins by NHC-catalyzed nucleophilic substitution

Coumarins are bioactive; consequently their syntheses are of importance to medicinal chemists. We describe the one-step organocatalytic syntheses of 4-acylcoumarins from 4-chlorocoumarin. The leaving group at the 4-position of the coumarin was replaced by aroyl groups that originate from aromatic aldehydes by NHC-catalyzed umpolung. 4-Acylthiocoumarins and 2-acylquinolin-2-ones were also prepared using this method. These are the first examples of nucleophilic substitutions at the β-carbons of enones to afford γ-ketoenones.     

Immobilization of Ethynyl-π-Extended Electron Acceptors with Amino-Terminated SAMs by Catalyst-Free Click Reaction

Surface modification of SiO₂ using a catalyst-free quantitative reaction between an amine and an ethynyl-π-extended naphthalenediimide was investigated. A post-reaction method, in which the catalyst-free reaction was performed at the surface after the formation of amino-terminated self-assembled monolayers (SAMs), resulted in dense, uniform modification of the SiO₂ surface with the naphthalenediimide molecules. Both X-ray reflectivity and angle-resolved X-ray photoemission spectroscopy showed consistent results for the layer thickness and density. In contrast, a pre-reaction method, in which an amino-silane and the ethynyl-π-extended naphthalenediimide reacted first and then formed a SAM, afforded a sparse SAM on the SiO₂ surface, probably due to the steric hindrance of the naphthalenediimide moieties. The in situ decoration of the SiO₂ surface by a catalyst-free quantitative reaction offers a facile route for modifying surface properties with various π-conjugated molecules suitable for many applications.