Cytotoxic acetylenes from Panax quinquefolium

Three new cytotoxic polyacetylenes, PQ-1 (1), PQ-2 (2) and PQ-3 (3), have been isolated from Panax quinquefolium. The structures of these acetylenes were determined by analyses of their 1H-1H and 1H-13C COSY spectra. All these compounds exhibited strong cytotoxic activities against leukemia cells (L 1210) in tissue culture.     

Mutation detection in the drug-resistant hepatitis B virus polymerase gene using nanostructured reverse micelles.

The emergence of drug-resistant hepatitis B virus (HBV) has been reported in patients with prolonged administration of lamivudine, which is a potent drug for the prevention of HBV infection. Lamivudine-resistant HBV has several types of mutations at the YMDD motif of its DNA polymerase. We successfully demonstrated that monitoring the hybridization behavior in nanostructured reverse micelles enables us to detect single nucleotide polymorphisms (SNPs). With the aid of reverse micelles, a model 40-mer oligonucleotide containing a single-base substitution was clearly distinguished from the normal, complementary oligonucleotide. In addition, we extended this technique to a high-throughput analysis. The results obtained with a 96-well micro-plate reader indicated the possibility of SNPs detection toward multiple samples of patients.     

Development of a “Built-in” Scanning Near Field Microscope Head for an Atomic Force Microscope System and Stress Mapping of an Al2O3/ZrO2 Eutectic Composite

We constructed a scanning near-field optical microscope (SNOM) on a commercially available atomic force microscopy (AFM) apparatus (SPM-9500J2; Shimadzu Corp.) to measure the stress distribution in ceramic composite materials. Features of our SNOM system are: (1) a compact SNOM head substituted for the original AFM head; (2) a wide scanning range (125 × 125 μm²) inherited from the original scanner; (3) use of conventional shear-force regulation; (4) an optical system for the illumination-collection (I-C) mode; (5) excitation by a 488 nm line of an Ar-ion laser, and (6) light detection by photon counting or a polychromator equipped with an electronically cooled charge coupled device (CCD). This SNOM system was used to measure the surface structure and stress distribution of an Al₂O₃/ZrO₂ eutectic composite. We simultaneously measured topographic images and fluorescence spectra of an Al₂O₃/ZrO₂ eutectic composite. We estimated its peak intensity, peak position, and peak width from the fluorescence spectrum during scanning, which respectively correspond to the abundance of Al₂O₃, stress in the grain, and the anisotropy of that stress. Mapping images showed that the stress and its anisotropy were weaker in the center of the Al₂O₃ grain than its boundary between Al₂O₃ and ZrO₂. That observation suggests that Al₂O₃ underwent intense anisotropic stress induced by volume expansion in the phase transition of ZrO₂ from the cubic phase to the monoclinic phase during preparation.     

FMS scheduling based on timed Petri Net model and reactive graph search

This paper presents a new scheduling method for manufacturing system based on the Timed Petri Net model and a reactive fast graph search algorithm. The following two typical problems are addressed in this paper. (1) Minimization of the maximum completion time. (2) Minimization of the total tardiness. As for the problem (1), a new search algorithm which combines the RTA^∗ and a rule-based supervisor is proposed. As for problem (2), the original Petri Net model is converted to its reverse model and the algorithm developed for the problem (1) is applied, regarding the due date as the starting time in the reverse model. Some numerical experiments are carried out to demonstrate usefulness of our algorithm.     

Identifying Linking-Pin Organizations in Inter-Organizational Networks

Within the large literature on inter-organizational networks, there has been some discussion of linking-pin organizations and the role they play in integrating these networks. Based on this verbal specification of linking-pin organizations, we construct operational criteria and empirical methods for identifying these structurally important organizations in potentially large and complex inter-organizational networks. These methods are based on ideas drawn from blockmodeling, structural holes, centrality and centralization of networks, and identifying cut-points in networks. These methods are applied to a constructed example and then to real empirical inter-organizational networks. Implications and contrasts with other methods are discussed, together with some open problems.     

Comparative studies of femtosecond to microsecond laser pulses on selective pigmented cell injury in skin

Threshold radiant exposures for grossly apparent immediate whitening and ultrastructural alterations of melanosomes in black guinea pig skin were determined for a series of red visible laser pulses ranging from 4 x 10(-4) to 6.5 x 10(-14) s. Threshold exposures for melanosomal injury were found to be independent of pulsewidth when the pulsewidths were below the estimated thermal relaxation time of melanosomes. Threshold radiant exposures for melanosomal injury were found to increase when the pulsewidths were approximately equal to or above the thermal relaxation time of melanosomes. At longer pulse durations, fracturing of melanosomes was not observed despite the longer exposures necessary for injury. Instead, perimelanosomal vacuoles were noted. These findings are consistent with the theory of selective photothermolysis and provide evidence for the thermal initiation of melanosomal disruption.     

Primary dependence of 7-aryl-2,5-di-t-butyl-1,3,5-cycloheptatriene valence tautomerism on the π-acceptor strength of the 7-aryl substituent

¹³C NMR studies showed that the population of the norcaradiene form of the title systems containing p-CH₃O, H, and p-CF₃ on the 7-aryl group increases in this order. The result is consistent with the prediction from the π-acceptor strength of the aryl group estimated by INDO calculations.