Coexistence of cluster and shell-model aspects in nuclear systems

We discuss cluster phenomena in light nuclei. As examples of typical cluster structures, we first review cluster structures of ¹²C, ¹⁶O, and ²⁰Ne, and then introduce some topics of cluster phenomena in light neutron-rich nuclei such as Be and C isotopes. A particular attention is paid on coexistence of cluster and shell-model aspects.     

Development of a rapid method for the quantitative determination of deoxynivalenol using Quenchbody

Quenchbody (Q-body) is a novel fluorescent biosensor based on the antigen-dependent removal of a quenching effect on a fluorophore attached to antibody domains. In order to develop a method using Q-body for the quantitative determination of deoxynivalenol (DON), a trichothecene mycotoxin produced by some Fusarium species, anti-DON Q-body was synthesized from the sequence information of a monoclonal antibody specific to DON. When the purified anti-DON Q-body was mixed with DON, a dose-dependent increase in the fluorescence intensity was observed and the detection range was between 0.0003 and 3 mg L⁻¹. The coefficients of variation were 7.9% at 0.003 mg L⁻¹, 5.0% at 0.03 mg L⁻¹ and 13.7% at 0.3 mg L⁻¹, respectively. The limit of detection was 0.006 mg L⁻¹ for DON in wheat. The Q-body showed an antigen-dependent fluorescence enhancement even in the presence of wheat extracts. To validate the analytical method using Q-body, a spike-and-recovery experiment was performed using four spiked wheat samples. The recoveries were in the range of 94.9–100.2%. The concentrations of DON in twenty-one naturally contaminated wheat samples were quantitated by the Q-body method, LC-MS/MS and an immunochromatographic assay kit. The LC-MS/MS analysis showed that the levels of DON contamination in the samples were between 0.001 and 2.68 mg kg⁻¹. The concentrations of DON quantitated by LC-MS/MS were more strongly correlated with those using the Q-body method (R² = 0.9760) than the immunochromatographic assay kit (R² = 0.8824). These data indicate that the Q-body system for the determination of DON in wheat samples was successfully developed and Q-body is expected to have a range of applications in the field of food safety.     

Large-Time Behavior of Solutions to Hyperbolic-Elliptic Coupled Systems

We are concerned with the asymptotic behavior of a solution to the initial value problem for a system of hyperbolic conservation laws coupled with elliptic equations. This kind of problem was first considered in our previous paper. In the present paper, we generalize the previous results to a broad class of hyperbolic-elliptic coupled systems. Assuming the existence of the entropy function and the stability condition, we prove the global existence and the asymptotic decay of the solution for small initial data in a suitable Sobolev space. Then, it is shown that the solution is well approximated, for large time, by a solution to the corresponding hyperbolic-parabolic coupled system. The first result is proved by deriving a priori estimates through the standard energy method. The spectral analysis with the aid of the a priori estimate gives the second result.     

Phosphorescence and photochemical properties of benzophenone included within alkali metal cation-exchanged ZSM-5 zeolites

The phosphorescence properties of benzophenone included within alkali metal cationexchanged ZSM-5 zeolites were investigated to clarify the effects of the micro-environment of hostadsorbents on the electronic excited states of guest-molecules included within the restricted void spaces. Benzophenone included within such cation-exchanged ZSM-5 zeolites was found to exist in both a protonated and hydrogen-bonded form. It was found that exchanging the cations dramatically affects the ratio of their contents. Photolysis of these systems revealed that both benzhydrol and benzpinacol were the main products, their yields strongly depending on the kind of the cations exchanged. Especially, the protonated species was found to play a significant role in the photoreactions observed with benzophenone included within zeolite cavities.     

Chemoenzymatic synthesis of glycoconjugate polymers starting from nonreducing disaccharides

Here we report the chemoenzymatic synthesis and recognition function of glycoconjugate polymers carrying nonreducing disaccharides [α-D -glucopyranosyl-(1-1)-α-D -glucopyranoside (trehalose) and α-D -galactopyranosyl-(1-1)-α-D -glucopyranoside (Gal-type trehalose)]. The lipase-catalyzed esterification of the disaccharides with divinyl sebacate is completely selective at the primary Glc 6-OH position of trehalose and at the Gal 6-OH position of Gal-type trehalose. The resultant vinyl esters can be polymerized to yield glycoconjugate polymers with poly(vinyl alcohol) backbones. The interactions of the glycoconjugate polymers with lectins (concanavalin A and Bandeiraera simplicifolia) are amplified because of the glycocluster effect. The polymer carrying pendant α-D -galactopyranosyl-(1-1)-α-D -glucopyranoside shows inhibition activity against Shiga toxin-1 based on a stereochemical structure similar to that of globosyl Gb2 disaccharide. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4598–4606, 2004     

Facile and efficient synthesis of lactols by a domino reaction of 2,3-epoxy alcohols with a hypervalent iodine(III) reagent and its application to the synthesis of lactones and the asymmetric synthesis of (+)-tanikolide

The domino reaction of 2,3-epoxy-1-alcohol derivatives, namely tetrasubstituted 2,3-epoxy-1-alcohols and 2- or 3-alkyl trisubstituted 2,3-epoxy-1-alcohols, with PhI(OCOCF(3))(2) in the presence of H(2)O is described in detail. In this reaction, several types of lactol derivatives can be directly obtained from the 2,3-epoxy-1-alcohol derivatives in a single operation. The obtained lactols were successively converted into the corresponding lactones. This reaction is applicable to the construction of optically active lactone compounds. The asymmetric total synthesis of (+)-tanikolide, an antifungal marine natural product, has been effectively achieved by using this reaction.     

Capillary electrophoretic studies on the photogenotoxic potential of pharmaceutical substances

Drug-induced phototoxic skin responses, including photoirritation, photoallergy and photogenotoxicity, are identified as adverse reactions. In this study, we attempted to develop effective analytical tools to predict the photogenotoxic potential of pharmaceutical substances with the use of pBR322 DNA, a plasmid DNA. pBR322 DNA was irradiated with simulated solar light in the presence of photosensitizers, and its structural conversion was assessed by agarose gel electrophoresis (AGE), transmission electron microscopy (TEM) and capillary gel electrophoresis (CGE). The generation of reactive oxygen species (ROS) from photoirradiated photosensitizers was also assessed by spectrophotometrical determination. Concomitant ultraviolet (UV) exposure of pBR322 DNA and photosensitizers resulted in significant oxidative damage to the DNA, as evidenced by AGE, TEM and CGE data, indicating a structural transition from supercoiled form to open circular form. Photosensitizer-induced DNA damage was attenuated by the addition of radical scavengers, especially sodium azide, a typical scavenger of singlet oxygen (1 O2), and enhanced by the addition of deuterium water, an enhancer of the life time of 1 O2. These data, taken together with the results of the ROS assay, suggest that singlet oxygen might act as a major toxic species in quinine-induced photogenotoxicity. The structural analysis of plasmid DNA by CGE after exposure to UVA/B in the presence of photosensitizers could be automated, allowing easy, fast and highly reliable prediction for the photogenotoxic potential of a large number of drug candidates.     

Amyloid-beta detection with saccharide immobilized gold nanoparticle on carbon electrode

The electrochemical sensing of saccharide-protein interactions using a couple of sialic acid derivatives and Alzheimer's amyloid-beta (Abeta) is described. The densely-packed saccharide area for recognition of protein was fabricated onto a carbon electrode by three steps, which were electrochemical deposition of Au nanoparticles on a screen printed strip, self-assembled monolayer (SAM) formation of the acetylenyl group on Au nanoparticles, and the cycloaddition reaction of an azide-terminated sialic acid to the acetylenyl group. The attachment of Abeta peptides to the sialic acid layer was confirmed by electrochemistry and atomic force microscopy imaging. The intrinsic oxidation signal of the captured Abeta(1-40) and (1-42) peptides, containing a single tyrosine (Tyr) residues, was monitored at a peak potential of 0.6 V (vs Ag/AgCl within this sensor) in connection with differential pulse voltammetry. The peak current intensities were concentration dependent. The proposed process provides new routes for analysis of saccharide-protein interactions and electrochemical biosensor development.     

A novel, intracellular antifreeze protein in an antarctic bacterium, Flavobacterium xanthum

One strain of Antarctic bacteria, Flavobacterium xanthum IAM12026, has a highly active antifreeze protein (AFP) in the intracellular space. The cell-free extract from strain IAM12026 after culturing at 4 degree C for 7 days in TSB medium, had activity of 0.04 degree C at a concentration of 0.7 mg/ml. The ice crystals formed do not have distinct facets without typically rounded shape and the changes of their morphology during the course of the thermal hysteresis (TH) measurement. The ice crystal 'burst' occurring at the end-point of the TH is dendritic with hexagonal symmetry. Also, this activity was not affected by the treatment of dialysis and the addition of EDTA. Furthermore, this cell-free extract had high levels of ice recrystallization-inhibiting (RI) activity like those of Fish AFPs. The AFP (FlAFP) was homogeneity purified using chromatography. A relative molecular mass of approximately 59,000 was calculated from gel filtration and SDS-PAGE data. The thermal stability of FlAFP was below 50 degree C, and TH value was absent above 60 degree C. The TH value of FlAFP was activated at 5.2 degree C by the addition of 0.5 M malate. This activation was decreased with increasing protein concentration. To our knowledge this is the first report on the high level of TH and RI activities of bacterial intracellular AFP.