Angular resolution of the Ohya air shower detector

Accurate measurements of the total number of muons in an air shower are important for the discrimination of showers produced by astronomical gamma rays from those produced by protons. In order to perform this discrimination, muon detectors with a total area of about 400 m² have been constructed in the Ohya stone mine. At ground level, scintillation detectors have been distributed for determining the total number of electrons in the air shower. The arrival direction of the air shower determined by usual timing information was examined using independent data on the arrival direction determined by muons in the shower. The angular resolution thus obtained at the shower maximum is 1.7° in the south-north plane and 2° in the east-west plane. The difference of the resolution is due to the asymmetric arrangement of scintillation detectors.     

Dimeric C34 Derivatives Linked through Disulfide Bridges as New HIV-1 Fusion Inhibitors

C34, a 34-mer fragment peptide, is contained in the HIV-1 envelope protein gp41. A dimeric derivative of C34 linked through a disulfide bridge at its C terminus was synthesized and found to display potent anti-HIV activity, comparable with that of a previously reported PEGylated dimer of C34REG. The reduction in the size of the linker moiety for dimerization was thus successful, and this result might shed some light on the mechanism of the suppression of six-helix bundle formation by these C34 dimeric derivatives. Addition of a Gly-Cys(CH₂CONH₂)-Gly-Gly motif at the N-terminal position of a C34 monomeric derivative significantly increased the anti-HIV-1 activity. This moiety functions as a new pharmacophore, and this might provide a useful insight into the design of potent HIV-1 fusion inhibitors.     

Low‐Molecular‐Weight CXCR4 Ligands with Variable Spacers

Low‐molecular‐weight CXCR4 ligands based on known lead compounds including the 14‐mer peptide T140, the cyclic pentapeptide FC131, peptide mimetics, and dipicolylamine‐containing compounds were designed and synthesized. Three types of aromatic spacers, 1,4‐phenylenedimethanamine, naphthalene‐2,6‐diyldimethanamine, and [1,1′‐biphenyl]‐4,4′‐diyldimethanamine, were used to build four pharmacophore groups. As pharmacophore groups, 2‐pyridylmethyl and 1‐naphthylmethyl are present in all of the compounds, and several aromatic groups and a cationic group from 1‐propylguanidine and 1,1,3,3‐tetramethyl‐2‐propylguanidine were also used. Several compounds showed significant CXCR4 binding affinity, and zinc(II) complexation of bis(pyridin‐2‐ylmethyl)amine moieties resulted in a remarkable increase in CXCR4 binding affinity.     

Enhancement of antimicrobial activity of neuropeptide Y by N-terminal truncation

The activity of neuropeptide Y (NPY) against Candida albicans, which was revealed to be fungicidal, was enhanced significantly by the truncation of amino acid residues at the N terminus. The most active peptides (MICs, approximately 1 microM) were about 10-fold more potent than the intact NPY (MIC, approximately 10 microM). The enhancement was weakened by the replacement of the N terminus by negatively charged residues and/or acylation of the alpha-amino group. These results suggest that only the alpha-helical region of NPY is necessary for the antimicrobial activity and that the net charge of the peptide is important for the activity.     

Unstable fracture criterion in a power-law hardening material

A fracture criterion for a pre-cracked plate subjected to large deformation is presented in a power-law hardening material based on the energy conservation law. First Hencky equations are applied to a non-linear elastic model in a small strain to derive the criterion and the theory is extended to a large strain case with the aid of numerical analysis. The criterion is expressed as a relation between a crack length and a remote fracture strain, and it is identical with Griffith's criterion when the power exponent is unity.Large strain and stress fields near a crack tip are also assessed. Experiments with pre-cracked steel plates well verify the theory, that is, the criterion based on elastic analysis appears to apply to an actual plastic material. The transition from the brittle fracture to the present unstable ductile fracture and a physical implication of the reduction of area in tension test are discussed.

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Résumé On présente un critère de rupture pour une tôle préfissurée soumise à une grande déformation dans une matériau durcissant suivant une loi parabolique et en se basant sur une loi de propagation de l'énergie. Les premières équations de Hencky sont appliquées à un modèle élastique non linéaire pour des déformations de faible amplitude en vue de dériver un critère, et la théorie est étendue au cas des grandes déformations à l'aide d'analyse numérique. Le critère est exprimé comme une relation entre la longueur de la fissure et une déformation à la rupture lointaine, et il est identique au critère de Griffith lorsque l'exposant de la loi de durcissement du matériau est l'unité.Les déformations en amplitude et les champs de contrainte au voisinage de l'extrémité de la fissure sont également prises en considération. Des expériences réalisées avec des tôles d'acier préfissurées vérifient la théorie de manière satisfaisante, c'est-à-dire que le critère basé sur l'analyse élastique apparait applicable à un matériau se comportant de façon plastique. La transition de la rupture fragile à une rupture ductile instable et les implications physiques de la striction lors de l'essai de traction sont discutées.

     

Development of a Time–Intensity Evaluation System for Consumers: Measuring Bitterness and Retronasal Aroma of Coffee Beverages in 106 Untrained Panelists

In order to develop products that are acceptable to consumers, it is necessary to incorporate consumers’ intentions into products’ characteristics. Therefore, investigation of consumers’ perceptions of the taste or smell of common beverages provides information that should be useful in predicting market responses. In this study, we sought to develop a time–intensity evaluation system for consumer panels. Using our system, we performed time–intensity evaluation of flavor attributes (bitterness and retronasal aroma) that consumers perceived after swallowing a coffee beverage. Additionally, we developed quantitative evaluation methods for determining whether consumer panelists can properly perform time–intensity evaluation. In every trial, we fitted an exponential function to measured intensity data for bitterness and retronasal aroma. The correlation coefficients between measured time–intensity data and the fitted exponential curves were greater than 0.8 in about 90% of trials, indicating that we had successfully developed a time–intensity system for use with consumer panelists, even after just a single training trial using a nontrained consumer. We classified participants into two groups based on their consumption of canned coffee beverages. Significant difference was observed in only AUC of sensory modality (bitterness compared with retronasal aroma) among conventional TI parameters using two‐way ANOVA. However, three‐way ANOVA including a time course revealed significant difference between bitterness and retronasal aroma in the high‐consumption group. Moreover, the high‐consumption group more easily discriminated between bitterness and retronasal aroma than the low‐consumption group. This finding implied that manufacturers should select consumer panelists who are suitable for their concepts of new products.     

Calcium phosphate composite materials including inorganic powders,BSA or duplex DNA prepared by W/O/W interfacial reaction method

We reported before that inorganic reaction occurring at the interface of W/O/W emulsion is advantageous to produce hollow spheres (microcapsules) of inorganic matrices such as silica. This process enables us to include various materials into inorganic matrices directly. Calcium phosphates were also produced from NH₄H₂PO₄ and Ca(OH)₂ by this interfacial reaction method. Various biomaterials are directly incorporated into crystalline calcium phosphate matrices, when the biomaterials are added to the inner water phase of the W/O/W emulsion. ZrO₂ and Al₂O₃ powders were effectively encapsulated in calcium phosphates such as hydroxyapatite (HAp). The images of backscattered electron of FE–SEM observations indicated that ZrO₂ particles were included in HAp, while they adhered to the surface of HAp in the case of a simple precipitation method. Biomacromolecules such as BSA and duplex DNA were also included in HAp using the inner water phases dissolving them. Fluorescent microscopy observations revealed that biomacromolecules incorporated in HAp localized in some domains of the HAp matrices. Biomacromolecules thus included were scarcely liberated into deionized water, indicating their strong encapsulation in HAp. This general and simple methodology will provide various composite materials of calcium phosphates, which are applicable to regenerative medicine, DDS, GDS and more.     

Microarray of human P450 with an integrated oxygen sensing film for high-throughput detection of metabolic activities

A microarray chip containing human P450 isoforms was constructed for the parallel assay of their metabolic activities. The chip had microwells that contained vertically integrated P450 and oxygen sensing layers. The oxygen sensing film was made of an organically modified silica film (ORMOSIL) doped with tris(4,7-diphenyl-1,10-phenanthroline) ruthenium dichloride (Ru(dpp)(3)Cl(2)). Human P450s (23 types) expressed in E. coli and purified as membrane fractions were immobilized in agarose matrixes on the oxygen sensing layer. The activities of P450s were determined by evaluating the fluorescence intensity enhancement of the oxygen sensor due to the oxygen consumption by the metabolic reaction. By normalizing the responses with the amounts of oxygen sensor and P450 enzymes in microwells, we could obtain fluorescence enhancement patterns that were characteristic to the combination of P450 isoforms and substrate material. The patterns obtained from two psoralen derivatives resembled each other, whereas a structurally different substrate (capsaicin) resulted in a distinct pattern. These results suggest the potential of the microarray to analyze the activities of diverse P450 isoforms in a high-throughput fashion. Furthermore, mechanism-based inactivation (MBI) of P450 could be detected by successively incubating a chip with different substrate solutions and measuring the residual activities.