Photostimulated luminescence of corrugated fiberboard as an additional screening method for detecting radiated foods

In this study, PSL of non-irradiated and irradiated corrugated fiberboards (CFs) was investigated to evaluate the possibility that CFs can be used as alternative specimens for the screening detection method of food irradiation. The irradiation at a dose of only 0.15 kGy increased PSL signals of the CF over 1 order of magnitude. The PSL signals increased with increasing in gamma irradiation dose and became almost saturated at a dose of 5 kGy. The core of CFs showed PSL signals sufficient for distinguishing irradiated from non-irradiated at least 6 months after irradiation even though the CF was exposed to light and the environmental temperature increased to 50 °C. These results suggest that the PSL property of the core of CFs is useful for detecting irradiation. However, the large variation of PSL signals among CFs made it difficult to set a well-defined “positive” threshold limit to distinguish irradiated from non-irradiated completely. All of the non-irradiated CFs showed PSL signals above 10³ counts, which is much higher than that detected for foods. It is apparent that the threshold limit of EN 13751 is not applicable to detecting irradiated CFs. More detailed collaborative research with large number of samples is needed to establish new threshold limits involving “intermediate” classification.     

Effect of surrounding gas temperature on the morphological evolution of TiO2 nanoparticles generated by laser ablation in tubular furnace

Titanium oxide nanoparticles are synthesized by laser ablation of Ti target in oxygen atmosphere under well-controlled temperature profiles in a tubular furnace. The size and the shape of generated nanoparticles are varied by changing the temperature of furnace. The mobility-based size distributions of generated air-borne nanoparticles are measured using a scanning mobility particle sizer, and the size distributions of primary particles are analyzed by a scanning electron microscope. When the particles are generated by laser ablation at the room temperature, the particles are agglomerates in gas phase with the average mobility diameter of 117 nm and the mean diameter of primary particles of 11 nm. The primary particle diameter increases from 11 to 24 nm by raising the furnace temperature up to 800 °C. Since the mass of Ti vapor ablated from a target is found to be constant regardless of the furnace temperature, this particle growth may be attributed to the reduction in nuclei number as a result of mild quenching at higher temperatures. As the temperature reaches higher than 1,000 °C, the mobility diameter suddenly drops and the primary particle diameter increases due to sintering, and at 1,200 °C the mobility diameter coincides with the primary particle diameter. Since the laser oven method offers an independent control of vapor concentration and the temperature of surrounding atmosphere, it is an effective tool to study the formation process of nanoparticles from primary particles with a given size.     

High-Pressure Phase Relationships for FeS

Phase relationships for FeS polymorph have been studied at the pressure of 16-20 GPa and temperature of 300-1350 K by in situ X-ray observation using a large volume high-pressure apparatus and a synchrotron radiation. Contrary to Fei's prediction [1], we found the stability field of NiAs-type phase of FeS extending at least to 18 GPa. Results of in situ X-ray observation correspond with the NiAs-hexagonal phase boundary determined by Kusaba et al . [2, 3]. Assuming the straight NiAs-hexagonal phase boundary, we estimate that the NiAs-hexagonal-liquid triple junction is located at 39.5 GPa and 2300 K.     

Structure Effect of Solute on Orientational Order in Binary Mixture by 2H-NMR and Molecular Simulations

Abstract

The orientational order parameters of six solutes with different shapes and sizes dissolved in two nematic solvents have been measured as a function of temperature. The parameter, S^xx-S^yy is correlated with the molecular geometrical structure, while S^zz is affected by not only the geometry but also the anisotropy in the polarizability. The molecular dynamics simulations are carried out using a realistic atom-atom potential for evaluating the ordering properties in the nematic phase. The results provide reasonable values of S^zz corresponding to experimental ones for solutes and solvents, and also a prediction of uniaxiality for the nematic phase.     

Brevisulcenal-F: a polycyclic ether toxin associated with massive fish-kills in New Zealand

A novel marine toxin, brevisulcenal-F (KBT-F, from karenia brevisulcata toxin) was isolated from the dinoflagellate Karenia brevisulcata. A red tide of K. brevisulcata in Wellington Harbour, New Zealand, in 1998 was extremely toxic to fish and marine invertebrates and also caused respiratory distress in harbor bystanders. An extract of K. brevisulcata showed potent mouse lethality and cytotoxicity, and laboratory cultures of K. brevisulcata produced a range of novel lipid-soluble toxins. A lipid soluble toxin, KBT-F, was isolated from bulk cultures by using various column chromatographies. Chemical investigations showed that KBT-F has the molecular formula C(107)H(160)O(38) and a complex polycyclic ether nature. NMR and MS/MS analyses revealed the complete structure for KBT-F, which is characterized by a ladder-frame polyether scaffold, a 2-methylbut-2-enal terminus, and an unusual substituted dihydrofuran at the other terminus. The main section of the molecule has 17 contiguous 6- and 7-membered ether rings. The LD(50) (mouse i.p.) for KBT-F was 0.032 mg/kg.     

Design, synthesis and functional analysis of dansylated polytheonamide mimic: an artificial Peptide ion channel

We report herein the design, total synthesis, and functional analysis of a novel artificial ion channel molecule, designated as dansylated polytheonamide mimic (3). The channel 3 was designed based on an exceptionally potent cytotoxin, polytheonamide B (1). Our strategy for the development of synthetic ion channels, which could be easily derivatized for various functions, involved two key features. First, the structure of 1 was simplified by replacing many of nonproteinogenic amino acid residues which required multistep synthesis by commercially available amino acids while retaining those residues necessary for folding. It significantly reduced the number of synthetic steps and facilitated a practical chemical construction of 3. Second, the introduction of propargyl glycine at residue 44 enabled facile installation of dansyl group as a reporter of the membrane localization of 3. Application of a newly designed protective group strategy provided efficient construction of the 37 amino acid sequence of residues 12-48 through one automatic solid-phase peptide synthesis. After peptide cleavage from the resin, 3 was synthesized via dansyl group introduction and one fragment-coupling reaction with residues 1-11, followed by the global deprotection. The simplified mimic 3 exhibited potent cytotoxicity toward p388 mouse leukemia cells (IC(50) = 12 nM), effectively induced ion transport across the lipid bilayers of liposomes, and displayed H(+) and Na(+) ion channel activities. Because of its simplified yet functional scaffold structure with a potential for diversification, our rationally designed ion channel molecule should be useful as a novel platform for developing various cytotoxic channel molecules with additional desired functions.     

High resolution N2 adsorption isotherms at 77.4 K and 87.3 K by carbon blacks and activated carbon fibers--analysis of porous texture of activated carbon fibers by αs-method

The standard α(s)-data of N(2) at 87.3 K by graphitized and nongraphitized carbon black samples (GCB-I and NGCB) (cf.Figs. 3 and 4) have been determined on the basis of the high resolution adsorption isotherms of N(2) at 87.3 K, which were repeatedly measured in the pressure range of p/p(o)=5×10(-8)-0.4. The high resolution adsorption isotherms of N(2) by two kinds of activated carbon fibers (ACF-I and ACF-II) were measured from p/p(o)=10(-7) to p/p(o)=0.995 at 77.4 K and from p/p(o)=10(-7) to p/p(o)=0.4 at 87.3 K. Combination of the adsorption isotherms by ACF-I and ACF-II with the standard α(s)-data by NGCB at 77.4 K and 87.3 K make it possible to construct the high resolution α(s)-plots from very low filling (1%) to complete filling (100%). The high resolution α(s)-plots of N(2) at 77.4 K and 87.3 K were analyzed. On the basis of the analyzed result, the porous textures of ACF-I and ACF-II will be discussed.     

Efficient Swern oxidation and Corey–Kim oxidation with ion-supported methyl sulfoxides and methyl sulfides

The Swern oxidation of various benzylic and allylic alcohols, primary alcohols, and secondary alcohols with two ion-supported methyl sulfoxides A-1 (C₆) and B-1 (C₁₀), and oxalyl chloride in the presence of triethylamine in dichloromethane, followed by simple diethyl ether extraction of the reaction mixture, gave the corresponding aldehydes and ketones, respectively, in good yields with high purity. Similarly, the Corey–Kim oxidation of various benzylic and allylic alcohols, primary alcohols, and secondary alcohols with two ion-supported methyl sulfides A-2 (C₆) and B-2 (C₁₀), and N-chlorosuccinimide in the presence of triethylamine in dichloromethane, followed by simple diethyl ether extraction of the reaction mixture, furnished the corresponding aldehydes and ketones, respectively, in good yields with high purity. Both reactions did not produce any unpleasant odor at all. In the Swern oxidation, ion-supported methyl sulfides were recovered in high yields and could be re-oxidized to produce ion-supported methyl sulfoxides A-1 (C₆) and B-1 (C₁₀), for reuse in the same oxidation. In the Corey–Kim oxidation, ion-supported methyl sulfides A-2 (C₆) and B-2 (C₁₀) were recovered in high yields and could be also reused for the same oxidation.     

Design of a bioactive small molecule that targets the myotonic dystrophy type 1 RNA via an RNA motif-ligand database and chemical similarity searching

Myotonic dystrophy type 1 (DM1) is a triplet repeating disorder caused by expanded CTG repeats in the 3'-untranslated region of the dystrophia myotonica protein kinase (DMPK) gene. The transcribed repeats fold into an RNA hairpin with multiple copies of a 5'CUG/3'GUC motif that binds the RNA splicing regulator muscleblind-like 1 protein (MBNL1). Sequestration of MBNL1 by expanded r(CUG) repeats causes splicing defects in a subset of pre-mRNAs including the insulin receptor, the muscle-specific chloride ion channel, sarco(endo)plasmic reticulum Ca(2+) ATPase 1, and cardiac troponin T. Based on these observations, the development of small-molecule ligands that target specifically expanded DM1 repeats could be of use as therapeutics. In the present study, chemical similarity searching was employed to improve the efficacy of pentamidine and Hoechst 33258 ligands that have been shown previously to target the DM1 triplet repeat. A series of in vitro inhibitors of the RNA-protein complex were identified with low micromolar IC(50)'s, which are >20-fold more potent than the query compounds. Importantly, a bis-benzimidazole identified from the Hoechst query improves DM1-associated pre-mRNA splicing defects in cell and mouse models of DM1 (when dosed with 1 mM and 100 mg/kg, respectively). Since Hoechst 33258 was identified as a DM1 binder through analysis of an RNA motif-ligand database, these studies suggest that lead ligands targeting RNA with improved biological activity can be identified by using a synergistic approach that combines analysis of known RNA-ligand interactions with chemical similarity searching.     

Chemical synthesis of intentionally misfolded homogeneous glycoprotein: a unique approach for the study of glycoprotein quality control

Biosynthesis of glycoproteins in the endoplasmic reticulum employs a quality control system, which discriminates and excludes misfolded malfunctional glycoproteins from a correctly folded one. As chemical tools to study the glycoprotein quality control system, we systematically synthesized misfolded homogeneous glycoproteins bearing a high-mannose type oligosaccharide via oxidative misfolding of a chemically synthesized homogeneous glycopeptide. The endoplasmic reticulum folding sensor enzyme, UDP-glucose:glycoprotein glucosyltransferase (UGGT), recognizes a specific folding intermediate, which exhibits a molten globule-like hydrophobic nature.