Improved calculation of band gap of Sr2Bi2O5 crystal using modified Becke–Johnson exchange potential

The electronic structure of Sr₂Bi₂O₅ is calculated by the scalar-relativistic full potential linearized augmented plane wave (FLAPW+lo) method using the modified Becke–Johnson potential combined with the local density approximation correlation (MBJ–LDA). Both the valence band maximum (VBM) and conduction band minimum (CBM) exist at the Γ-point, indicating that Sr₂Bi₂O₅ is a direct-band-gap material. The band gap is calculated to be 3.17 eV, which is very close to the experimental value. This result is in great contrast to the underestimation based on the GGA calculation. On the other hand, there is only a small difference in the effective masses of holes and electrons photogenerated near the VBM and CBM for the MBJ–LDA and GGA approaches. The optical properties of Sr₂Bi₂O₅ are calculated from the complex dielectric function ε(ω)=ε₁(ω)+iε₂(ω). A highly polarized peak is observed at 3.5 eV in the ε₂(ω) function. Furthermore, the absorption coefficient estimated from the MBJ–LDA is very similar to that from the experimental result.     

Reentrant nematic phase in 4-alkyl-4′-cyanobiphenyl (nCB) binary mixtures

The appearance of reentrant nematic phase was identified in nCB/8CB (n = 1–6) binary mixtures using differential scanning calorimetry, small-angle X-ray diffraction and polarising microscopy with photomonitor. Phase diagrams can roughly be unified if plotted against the average number of alkyl chain length. Distinction was recognised for the phase boundaries between nematic and smectic A phases of even and odd n of the minor component nCB. The character of 8CB as ‘SmA former’ is briefly discussed.     

High-efficiency electro-optic amplitude modulation with delayed coherent addition

Amplitude modulation of laser light is required for resonant sideband extraction employed in gravitational-wave detectors. Amplitude modulation with electro-optic phase modulators is realized by interferometric phase-to-amplitude conversion. Although two outputs modulated at opposite phases to each other are obtained, usually only one of them is utilized and the other is abandoned. The reuse of this abandoned light improves the power efficiency of the modulation. This can be realized by inverting the modulation phase of one output with a delay line and adding it to the other coherently. Moreover, this system selects a high-efficiency operating point and modulates the light in a linear range. We demonstrate that the modulation system can be operated with a power loss that is due only to the losses of the optical components.     

Challenge of advanced low temperature fuel cells based on high degree of freedom of group 4 and 5 metal oxides

To obtain an ideal electrocatalysts for hydrogen fuel cells, we investigated group 4 and 5 oxide-based compounds because of their high degree of freedom. First-principles calculations revealed that oxide surfaces such as those of titanium oxide could break down the universal scaling to achieve the ideal state of the oxygen reduction reaction. We experimentally clarified that the active sites were oxygen vacancies for tantalum and zirconium oxides, in addition to doped foreign elements and crystalline structures for titanium oxide. We successfully demonstrated that precious metal-free and carbon-free oxide-based cathodes have high quality active sites and superior durability in 0.1 M sulfuric acid at 80°C. Our strategy was developed as follows: (1) Active sites are created on the oxide surface by modifying the crystalline structure and electronic states and (2) electrons participating in the oxygen reduction reaction are supplied by nanosized oxide particles and oxide films through the tunneling effect of electrons.     

A Palladium‐Nanoparticle and Silicon‐Nanowire‐Array Hybrid: A Platform for Catalytic Heterogeneous Reactions

We report the development of a silicon nanowire array‐stabilized palladium nanoparticle catalyst, SiNA‐Pd. Its use in the palladium‐catalyzed Mizoroki‐Heck reaction, the hydrogenation of an alkene, the hydrogenolysis of nitrobenzene, the hydrosilylation of an α,β‐unsaturated ketone, and the C‐H bond functionalization reactions of thiophenes and indoles achieved a quantitative production with high reusability. The catalytic activity reached several hundred‐mol ppb of palladium, reaching a TON of 2 000 000.     

How is it possible to obtain buried interface information through very thick films using a hard-X-ray PEEM?

We analyze the excitation of secondary electrons by hard-X-rays in subsurface layers. By studying core-excited photoelectron lines and their plasmon satellites in photoemission spectra, we show how electrons excited by hard-X-rays can carry information from deep regions deep within the sample to the surface. It is believed that the decay of high-energy photoelectrons via plasmon-loss is strongly related to the production of secondary electrons. For high-energy electrons, however, the momentum transfer to plasmons is small compared to the electron’s initial momentum, so the lateral position on the surface from which the secondary electrons are emitted is close to that of the atom initially excited by the hard-X-rays. This explains why the spatial resolution of hard-X-ray photoelectron emission microscope (HX-PEEM) images is good even if the buried interface is covered by a film with a thickness many times the inelastic mean free path of the primary electrons. This argument explains well recent HX-PEEM results.     

Surface acetylation of bacterial cellulose

Bacterial cellulose was partially acetylated by the fibrous acetylationmethod to modify its physical properties, while preserving the microfibrillarmorphology. The overall degree of substitution was varied from 0.04 to 2.77 bychanging the amount of acetic anhydride added. X-ray diffraction of thepartially acetylated samples showed the crystalline pattern of unmodified celluloseI up to moderate degrees of acetylation, and the change in peak widthsindicatedthat acetylation proceeded from the surface of microfibrils, leaving the coreportion unreacted. Scanning electron microscopy revealed that even low levelsofacetylation were effective to maintain the original microfibrillar morphologyofbacterial cellulose on direct drying from water.     

Charge transfer in duplex DNA containing mismatch

A theory for charge transfer between the electrode and the donor/acceptor molecule coupled through a DNA bridge in solution is developed. We explore the crossover between the coherent tunneling and the incoherent sequential transfer regimes by varying the electrode potential and discuss the effects of single-base mismatches in DNA duplex in both regimes. In the former regime a single-base mismatch in DNA duplex causes a reduction in the charge transfer rate simply by decreasing the electron tunneling matrix element, however, in the latter regime the effects are rather complicated.     

Microvasculature of the olfactory organ in the Japanese monkey (Macaca fuscata fuscata).

Olfaction is an important and primitive sense. As its importance has changed with evolution, anatomic adjustments have occurred in its structure and vasculature. Primates are a family of vertebrates that have had to develop their visual system to adapt to the arboreal environment and have evolved from a macrosmatic to a microsmatic species as the optic system has enlarged. This has resulted in anatomic changes of a small but critical area at the base of the brain. This paper describes the three-dimensional vascular anatomy of the olfactory organ of the Japanese monkey (Macaca fuscata fuscata). This is best understood by dividing the organ into three parts: the olfactory tract, olfactory bulb, and olfactory nerves in the nasal mucosa. The bulb can be partitioned into an outer or cortical part and inner or medullary part. The vasculature and tissue were examined grossly and with light microscopy and scanning electron microscopy of vascular corrosion casts. The olfactory tract and bulb were supplied by an arteriole from the anterior cerebral artery on each side. The tract was supplied by capillaries running spirally with a coarse network. At the olfactory bulb, the arteriole ramified into the intracortical and medullary branches that formed capillary networks. The bulbar intracortical capillaries were divided into two layers with different densities and vascular patterns. The capillaries of the superficial layer had a ladder-like pattern. The branches that ran into the medulla of the olfactory bulb were more widely spaced. Twigs from the posterior ethmoidal artery ran along the nerve fiber and formed intra- and extrafascicular networks. Each region of the olfactory organ had characteristic three-dimensional vascular patterns that were related to their cellular architecture.     

Photon density wave for imaging through random media

The passage of a photon density wave through random media has been investigated extensively for medical imaging based on the diffusion approximation. In this paper, the photon density wave is studied based on the exact time-dependent vector radiative transfer theory. Both continuous and pulse photon density waves are analysed in a plane parallel medium using Mie scattering and the discrete ordinates method. The photon density wave shows superior properties over regular waves in several aspects. It has a narrower angular spectrum and maintains the original pulse shape. It also preserves the degree of polarization and increases the cross-polarization discrimination. These properties of a photon density wave suggest its potential for improving imaging. Thus, we apply the photon density wave to an imaging problem and show that it improves the quality of the images compared to other conventional imaging techniques.