Active Center Induced by Vibronic Interactions in V2O5/SiO2

The vibronic interactions in a photocatalyst, isolated vanadium oxide on silica, is investigated theoretically employing a vibronic model. The T ₁ state gives rise to a Jahn-Teller distortion after the excitation. The HOMO is destabilized against the JT distortion, while the system is stabilized because of the JT effect.     

Production of new antioxidant compound from mycosporine-like amino acid,porphyra-334 by heat treatment

In this study, we evaluated the antioxidant activity (diphenylpicrylhydrazyl (DPPH)-radical scavenging activity) of the low-molecular weight fraction of water-soluble Susabinori (Porphyra yezoensis) extract (LMF). DPPH-radical scavenging activity of LMF (65.5 μmol-Trolox eq/ml) was enhanced at temperatures over 100 °C (1.4, 2.0 and 2.4 times higher at 100, 110 and 120 °C, respectively). As a result of HPLC separations, a newly produced peak was observed in heat treated LMF, while a marked decrease of another peak was found after heat treatment of LMF. The decreased peak was identified as porphyra-334, which is a typical mycosporine-like amino acid, by ESI/MSⁿ analysis (protonated molecule [M + H]⁺ at m/z 347.1 and its fragment ion 303.1). The newly produced compound with [M + H]⁺ at m/z 329.1 was found to be a dehydrated compound of porhyra-334. The compound exhibited an extremely high-IC₅₀ value of 10.1 μg/ml in DPPH-radical scavenging activity, compared to porphyra-334 (>1000 μg/ml).     

Optimization of crystal microstructure in piezoelectric ceramics by multiscale finite element analysis

A multiscale finite element method based on homogenization theory is employed to optimize the microstructure of polycrystalline piezoelectric ceramics so as to maximize the homogenized macrostructural piezoelectric response. This analysis reveals that two specific microstructures, layered or alternating [1 1 1]-oriented structures, result in a piezoelectric response that exceeds that of the single-crystal. The layered structure consists of ordered 120°-rotated layers maximizing d₃₃₃, while the alternating structure consists of adjacent grains rotated by 180° in three dimensions optimizing d₃₁₁. These heterogeneous structures maximize the internal strain in polycrystalline aggregates by optimizing electrical and mechanical effects.     

Purification and properties of family-10 endo-1,4-beta-xylanase from Penicillium citrinum and structural organization of encoding gene

An extracellular endo-1,4-beta-xylanase was purified from the culture filtrate of a filamentous fungus, Penicillium citrinum strain FERM P-15944, grown on birch-wood xylan. The purified enzyme showed a single band on SDS-PAGE with an apparent M(r) of 31.6 kDa. The xylanase activity was optimal at pH 6.0 and 50 degrees C. Southern blot analysis indicated that the xylanase gene (xynB) was present as a single copy in the genome. The genomic DNA and cDNAs encoding this protein were cloned and sequenced. An open reading frame of xynB was interrupted by nine introns and encoded a presumed prepropeptide of 25 amino acids and a mature protein of 302 amino acids. Sequence alignment and the constructed neighbor-joining tree showed that the P. citrinum enzyme belongs to glycoside hydrolase family 10 and is closely related to several other xylanases from penicillia and black aspergilli. The xynB cDNA was functionally expressed in the methylotrophic yeast Pichia pastoris.     

Novel method for estimating viable Salmonella cell counts using real-time PCR

A novel method for estimating viable Salmonella Enteritidis cell counts with 5'-nuclease real-time PCR was developed in this study. Our method was based on the increase kinetics of the target DNA region (invA) of the microorganism growing in a food/clinical sample in a culture medium during incubation. The index of increase in the target DNA region studied here was threshold cycle, CT. A test Salmonella strain was grown in buffered peptone water at the optimal temperature (39 degrees C). As Salmonella cells were grown, the value of CT decreased with time, generating a downward sigmoidal curve. The slope of the curve was constant at various initial cell concentrations. With higher initial cell concentration, the CT value evaluated from the slope at a given time was lower. With this relationship, a novel method for estimating the initial viable cell concentration of a sample was developed. Dead Salmonella cells or bacteria other than the target cell caused deviation in the CT curve. Incubation in a selective media suppressed the deviation caused by other bacterial cells. We think that this method could be applied to many other microorganisms cultivable in a suitable medium.     

Application of an absorption-based surface plasmon resonance principle to the development of SPR ammonium ion and enzyme sensors

Two new types of surface plasmon resonance (SPR) sensors that can determine the concentration of ammonium cations and urea were realized based on the previously reported theory of the absorption-based SPR measurement method. The change of the dielectric constant caused by the change of the light absorption characteristics of dyes incorporated in a sensing membrane phase is utilized in these SPR sensors. The determination of ions using the SPR sensor was realized by detecting the SPR signals of the minimum reflectance related to the change of absorption spectra of the dye in the ion optode membrane consisting of an ammonium-selective ionophore (TD19C6) and a lipophilic cationic dye (KD-M11) that shows absorption spectral changes due to protonation and deprotonation. A SPR enzyme sensor that can determine the concentration of urea was prepared by the combination of this ion optode membrane and an enzyme membrane based on urease. With the newly developed SPR sensors, the intensity changes of the reflectance at the fixed SPR resonance angle are monitored, which is different from conventional SPR sensors where usually the change of the SPR resonance angles is detected. In a continuous-flow experiment using the SPR ion sensor for NH4+ ion determination, a dynamic measurement range from 10(-5) to 10(-2) M was achieved. In the case of the enzyme-based SPR urea sensor, a dynamic range from 10(-4) to 10(-1) M was observed in a stopped-flow batch arrangement. It is expected that this sensing technique can be applied for the SPR-based detection of a wide range of low molecular weight analytes.     

Characteristics of high-energy neutrons estimated using the radioactive spallation products of Au at the 500-MeV neutron irradiation facility of KENS

We carried out a shielding experiment of high-energy neutrons, generated from a tungsten target bombarded with primary 500-MeV protons at KENS, which penetrated through a concrete shield in the zero-degree direction. We propose a new method to evaluate the spectra of high-energy neutrons ranging from 8 to 500 MeV. Au foils were set in a concrete shield, and the reaction rates for 13 radionuclides produced by the spallation reactions on the Au targets were measured by radiochemical techniques. The experimental results were compared with those obtained by the MARS14 Monte-Carlo code. A good agreement (between them) was found for energies beyond 100 MeV. The profile of the neutron spectrum, ranging from 8 to 500 MeV, does not depend on the thickness of the concrete shield.     

Psychophysiological evaluation of simulator sickness evoked by a graphic simulator

The present study investigated the effects of simulator sickness, as an important bias factor on evaluation of emotional changes under the controlled condition of driving a car for 60 min at a constant speed (60 km/h) in a graphic simulator. Simulator sickness was measured and analyzed every 5 min using both subjective evaluation and physiological signals. Results of the subjective evaluation showed there was a significant difference between the rest and the driving conditions 10 min after the main experiment started and that the level of difference increased linearly with time. Analysis of the central and the autonomic nervous systems showed the significant differences in delta, theta, alpha and beta bands of an electroencephalogram (EEG), skin temperature, and the R-R interval between the rest and the driving conditions after about 5 min from the start of driving. In particular, there was the highest correlation between parameter of theta and subjective evaluation, and thus theta was considered an effective physiological parameter for numerically evaluating simulator sickness. The results indicate that physiological changes due to simulator sickness can be a bias factor in evaluation of human sensibility.     

The torsion of an infinite hollow cylinder with an external crack

This paper deals with the axially symmetric torsion of a hollow cylinder with an external crack. The mixed boundary value problem is reduced to a pair of dual series equations. These equations are shown to be equivalent to an infinite system of simultaneous equations. Numerical results are presented for stresses, displacement and stress intensity factors.