On the cohomology of free and twisted loop spaces

A natural extension of the cohomology suspension to a free loop space is constructed from the evaluation map and is shown to have good properties in cohomology calculation. This map is generalized to a twisted loop space which is a space of paths twisted by a given self-map of the underlying space. As an application, the cohomology of free and twisted loop spaces of classifying spaces of compact Lie groups, including some finite Chevalley groups, is calculated.     

Theoretical studies of molecules adsorbed on solid surfaces: I. Electronic spectra

The band shape of electronic spectra for a diatomic molecule adsorbed on a surface is studied using the adiabatic approximation. In this approximation, the Schrödinger equation for the total system is separated into those for electronic motion, intramolecular vibration, and low frequency motions (e.g., hindered molecular rotation and lattice vibration). Our theory is applied to the system of an admolecule on the (001) surface of fcc monatomic crystals. We determine the line shape of a vibronic transition for both chemisorption and physisorption cases. In chemisorption cases, a side band due to the low frequency motions can appear in the line shape of a vibronic transition. On the other hand, in physisorption cases, the line shape is a single peak. Moreover, we suggest theoretically a new experimental technique for exciting adsorbed molecules; for this purpose, we derive equations giving the cross sections for the electronic excitation of admolecules by using ion impact at grazing incidence. The admolecules can be excited by this method; the subsequent light emission can give information on the orientation of the admolecule on the surface and on the admolecule-surface species interaction.     

Preparation and characterization of complexes of liposomes with gold nanoparticles

Gold nanoparticles (Au NPs), which are extremely useful materials for imaging and photothermal therapy, typically require a drug delivery system to transport them to the affected tissue and into the cells. Since liposomes are approved as drug carriers, complexes of liposomes with Au NPs were considered ideal solutions to deliver Au NPs to the target site in vivo. In this study, we prepared complexes of various liposomes with Au NPs via physical absorption and characterized them. The time dependency of the surface plasmon resonance of this complex, which is a unique property of Au NPs, shows that the liposomes promote the formation of stable dispersions of Au NPs under isotonic conditions, even though intact Au NPs aggregate immediately. From a release assay of calcein from liposomes and transmission electron microscopy analysis, the Au NPs were complexed with liposomes without membrane disruption. These complexes could be formed by using cationic liposomes and polyethylene glycol-modified liposomes, as well as by using phosphatidylcholine liposomes, which are useful for drug and gene delivery. We proposed this kind of complex as a nanomedicine with diagnostic and therapeutic ability.     

CP/MAS (13)C NMR study of cellulose and cellulose derivatives. 2. Complete assignment of the (13)C resonance for the ring carbons of cellulose triacetate polymorphs

Complex ring (13)C resonance lines of the cross-polarization/magic angle spinning (CP/MAS) (13)C NMR spectra of cellulose triacetate (CTA) I and CTA II were completely assigned, for the first time, by (13)C-enriched CTA allomorphs. The (13)C-enriched CTA I was prepared by heterogeneous acetylation of bacterial cellulose which was biosynthesized by Acetobacter xylinum (A. xylinum) ATCC10245 from culture medium containing D-(2-(13)C)-, D-(3-(13)C)-, or D-(5-(13)C)glucose as a carbon source, while CTA II samples were obtained by solution acetylation of the (13)C-enriched bacterial celluloses. From comparison of the spectra of normal CTA prepared from ramie with those of the enriched CTA samples, it was revealed that all carbons composed of CTA I appeared as a singlet, while those of CTA II except for C1 were shown as equal-intensity doublets in the CP/MAS (13)C NMR spectrum. This finding suggests that CTA I is made up of one kind of glucopyranose residue while there are two magnetically inequivalent sites in the unit cell of CTA II in the same population.     

Temperature dependence of surface electronic structure of Si(111) surface

Temperature dependence of angle-resolved ultraviolet photoelectron spectra has been obtained for Si(111) surfaces starting with a thermally quenched “1 × 1” surface and ending with a high temperature “1 × 1” surface. it has been found that the surface state at 0.8 eV below the Fermi level exhibits degradation with the increase in temperature, which explains the difference of surface electronic structures between a quenched “1 × 1” surface and a high temperature “1 × 1” surface. Electron correlation effect in a dangling-bond derived surface state is postulated as a cause for the phenomenon.     

Existence of limit cycles for Liénard-type systems with p-Laplacian

The purpose of this paper is to give sufficient conditions under which an equivalent system to the equation has at least one stable limit cycle, where is the one-dimensional p-Laplacian. The main results are proved by means of phase plane analysis with the Poincaré-Bendixson theorem. Sufficient conditions are also given for the origin to be unstable and for all solutions to be bounded in the future. Jitsuro Sugie: Supported in part by Grant-in-Aid for Scientific Research 16540152     

Structural change in a series of protonated layered perovskite compounds, HLnTiO4 (Ln=La, Nd and Y)

A deuterated n=1 Ruddlesden-Popper compound, DLnTiO₄ (HLnTiO₄, Ln=La, Nd and Y), was prepared by an ion-exchange reaction of Na⁺ ions in NaLnTiO₄ with D⁺ ions, and its structure was analyzed by Rietveld method using powder neutron diffraction data. The structure analyses showed that DLaTiO₄ and DNdTiO₄ crystallized in the space group P4/nmm with a=3.7232(1) and c=12.3088(1) Å, and a=3.7039(1) and c=12.0883(1) Å, respectively. On the other hand, DYTiO₄ crystallized in the space group P2₁/c with a=11.460(1), b=5.2920(4), c=5.3628(5) Å and β=90.441(9)°. The loaded protons were found to statistically occupy the sites around an apical oxygen of TiO₆ octahedron in the interlayer of these compounds, rather than Na atom sites in NaLnTiO₄.     

Coherent heterodyne-assisted pulsed spectroscopy: sub-Doppler two-photon spectra of krypton, characterizing a tunable nonlinear-optical ultraviolet light source

A chirp-minimized, nanosecond-pulsed system has been developed to generate tunable coherent ultraviolet light at ∼212.5 nm by fourth-harmonic conversion of output from an amplified, injection-seeded optical parametric oscillator (OPO). Our CHAPS (coherent heterodyne-assisted pulsed spectroscopy) method is used to characterize the frequency stability and optical bandwidth of the system’s output radiation by recording sub-Doppler two-photon excitation spectra of krypton. In our new scanned-reference variant of CHAPS, the central frequency for each amplified OPO pulse is logged by the optical-heterodyne chirp-analysis software, with the frequency of the seed laser slowly tuned and monitored by a high-resolution wavemeter, unlike our previous implementation of CHAPS where the seed-laser frequency was fixed. For the amplified, up-converted pulses at ∼212.5 nm, our CHAPS measurements indicate an optical bandwidth of ∼100 MHz, consistent with the Fourier-transform limit of their duration (∼4.5 ns).