Wide-gap layered oxychalcogenide semiconductors: Materials, electronic structures and optoelectronic properties

Applying the concept of materials design for transparent conductive oxides to layered oxychalcogenides, several p-type and n-type layered oxychalcogenides were proposed as wide-gap semiconductors and their basic optical and electrical properties were examined. The layered oxychalcogenides are composed of ionic oxide layers and covalent chalcogenide layers, which bring wide-gap and conductive properties to these materials, respectively. The electronic structures of the materials were examined by normal/inverse photoemission spectroscopy and energy band calculations. The results of the examinations suggested that these materials possess unique features more than simple wide-gap semiconductors. Namely, the layered oxychalcogenides are considered to be extremely thin quantum wells composed of the oxide and chalcogenide layers or 2D chalcogenide crystals/molecules embedded in an oxide matrix. Observation of step-like absorption edges, large band gap energy and large exciton binding energy demonstrated these features originating from 2D density of states and quantum size effects in these layered materials.     

Business process integration as a solution to the implementation of supply chain management systems

In the domain of supply chain management (SCM), various software packages have been developed for planning business strategies. To solve the problem of system productivity in applying planning packages, we propose a solution concept, business process integration (BPI), which fuses workflow and enterprise application integration (EAI) technology. Two characteristic policies are included in BPI. The first is to design the minimum set of business processes for real-time information sharing with planning packages without changing other processes. The second is to integrate several systems with EAI technology and to manage their execution with a workflow tool. Based on these policies, we propose various design templates and integration adapters. Our evaluation shows that using BPI, a target system can be developed with less manpower, in less time, and with higher quality than previous methods.     

Low‐Energy Electron Beam Induced Charging and Secondary Electron Emission Properties of FEP Film Used on Satellite Surfaces

Many kinds of insulating materials are used outside a spacecraft. They include FEP films, polyimide films, and so on, and are used as thermal control materials. These materials are exposed to a charged‐particle environment around the spacecraft. Thus then become charged due to charged particles, especially electrons. It has been pointed out that charging of these materials is likely to cause discharges on the surfaces. From this viewpoint, we investigated the charging potential characteristics of 127‐μm‐thick FEP film, a typical thermal control material, by exposing it to electron irradiation at various energies below 20 keV. In the dependence of the charging potential on the electron energy, we found that the electron energy at which no charge‐up occurs is about 2.7 keV. This appears to be the energy at the which secondary electron emission yield becomes unity. This indicates that electron irradiation of FEP film with energies lower than 2.7 keV induces positive charging. From the charge decay characteristics after electron irradiation, the volume resistivity of the film was also obtained as a function of the electric fields in the bulk of the FEP film.     

Effect of drawing condition on mechanical properties and molecular orientation of self-reinforced poly(lactic acid) screws

Effects of extrusion ratio (ER) during extruding on mechanical properties of poly(lactic acid) (PLA) screws were investigated in terms of shear and twist strength. Shear strength increased by drawing, while twist strength decreased. This might be due to orientation of molecular chains during drawing. In order to evaluate orientation of molecular chains, orientation function in extruded billets was measured as a function of ER. Since orientation function increased with ER, drawing is effective method to improve shear strength of screw, where fibrous structure which was formed during extruding resisted shear stress in cross-section perpendicular to screw axis. Although orientation functions for billet extruded at ER 1.3–4 were equivalent, both strengths changed for the screw extruded at the range of this ER. Infrared spectra suggested transforming from α to β crystal for the billet extruded at the range of this ER. This result suggested that mechanical properties of screw also depended on the crystal forms.     

The correlation between the ionic degree of covalent bond comprising polymer main chain and the ionic yield due to mechanical fracture

The mechanical force to polymeric materials in vacuum at 77 K produces mechano radicals, mechano anions and mechano cations due to homogeneous and heterogeneous scissions of the covalent bonds comprising polymer main chain. The ionic degree of the covalent bond was estimated by calculating the “absolute ΔMulliken atomic charge,” which was defined as the difference between the Mulliken atomic charges of the two adjacent atoms comprising the covalent bond of the polymer main chain. The ionic yield of the covalent bond increased with increasing the absolute ΔMulliken atomic charge. The empirical formula for the ionic yield was obtained with the absolute ΔMulliken atomic charge, and indicates that the ionic yield could be estimated from its chemical structure.     

Characteristics of a-Si solar cells prepared by the super chamber at a high substrate temperature

A new approach to high-performance a-Si solar cells was studied. a-Si films prepared at a high substrate temperature (> 250°C) have a higher absorption coefficient and a low Si H₂ bond density. the effect of deposition temperature on the open-circuit voltage (V_oc) has been investigated systematically for glass/SnO2 Ipin/metal and glass/metal/nip/indium tin oxide (ITO) structure a-Si solar cells. The V_oc is found to depend strongly on the thermal history of the p/i interface. A short-circuit current of 19.5 mA/cm⁻⁻² was achieved for an a-Si solar cell using an a-Si i-layer with a thickness of 4000 Å, which was prepared at a substrate temperature of 270°C.     

Supramolecular Architectures of Nucleic Acid/Peptide Hybrids

Supramolecular architectures that are built artificially from biomolecules, such as nucleic acids or peptides, with structural hierarchical orders ranging from the molecular to nano-scales have attracted increased attention in molecular science research fields. The engineering of nanostructures with such biomolecule-based supramolecular architectures could offer an opportunity for the development of biocompatible supramolecular (nano)materials. In this review, we highlighted a variety of supramolecular architectures that were assembled from both nucleic acids and peptides through the non-covalent interactions between them or the covalently conjugated molecular hybrids between them.     

Mumefural and related HMF derivatives from Japanese apricot fruit juice concentrate show multiple inhibitory effects on pandemic influenza A (H1N1) virus

Fruit-juice concentrate of Japanese apricot (Prunus mume Sieb. et Zucc.) has been shown to be effective against influenza A infection in MDCK cells. In this study, we isolated five components from the fruit-juice concentrate of Japanese apricot, 5-(hydroxymethyl)-2-formylfuran (HMF), 1-[5-(2-formylfuryl)methyl]dihydrogen 2-hydroxypropane-1,2,3-tricarboxylate (mumefural, MF), 2-[5-(2-formylfuryl)methyl]dihydrogen 2-hydroxypropane-1,2,3-tricarboxylate (MF‘), 1-[5-(2-formylfuryl)methyl]hydrogen 1-hydroxyethane-1,2-dicarboxylate (MA1) and 2-[5-(2-formylfuryl)methyl]hydrogen 1-hydroxyethane-1,2-dicarboxylate (MA2), and investigated their inhibitory activities against the novel influenza A/Narita/1/2009 (H1N1) pandemic virus hemagglutinin and neuraminidase functions, which are essential for viral attachment and budding, respectively. An hemagglutination inhibition assay indicated that MF and MF‘ were effective at minimum hemagglutination concentrations of 3.1 and 6.3 mM, respectively. An inhibition study for sialidase activity of the neuraminidase spike showed that MF was the most active anti-sialidase compound with an IC₅₀ value of 0.21 ± 0.01 mM, followed by MA2 (IC₅₀, 0.71 ± 0.09 mM), MA1 (IC₅₀, 1.64 ± 0.31 mM) and MF‘(IC₅₀, 1.62 ± 0.22 mM). Furthermore, MF was shown to inhibit the growth of the pandemic virus in a dose-dependent manner (62 ± 3% inhibition at 5 mM). The results suggest that MF, a citric acid ester linked to HMF at the 1-position of the propane backbone, might be a lead compound for the development of anti-influenza A inhibitors.     

Vitamin E reduces cholesterol esterification and uptake of acetylated low density lipoprotein in macrophages

The effects of vitamin E on cholesteryl ester (CE) metabolism in 1774 cells were examined. Pretreatment of 1774 cells with vitamin E at concentrations above 50 μM significantly decreased acetylated low density lipoprotein (LDL)-induced incorporation of [¹⁴C]oleate into CF in cells in a dose-dependent manner. This was partly due to vitamin E Also significantly inhibiting the uptake of [³H]CE-labeled acetylated LDL by 1774 cells. A trend existed toward suppression of acyl-CoA:cholesterol acyltransferase (ACAT) activity in the cell lysate at high vitamin E concentration, but there was no effect on hydrolysis of CE. These data indicate that vitamin E reduces the uptake of modified LDL and suppresses ACAT activity, resulting in less cholesterol esterification in macrophages; a novel mechanism underlying the antiatherogenic properties of vitamin E.