High-spin isomer in 93Mo

The high-spin states of ⁹³Mo have been studied by a ⁸²Se( ¹⁶O, 5n) ⁹³Mo reaction at a beam energy of 100 MeV using techniques of in-beam -ray spectroscopy. Measurements of -t, --t coincidences, -ray angular distributions and -ray linear polarizations were performed. The high-spin isomer was found as a (39/2^-) state at about 9.7 MeV. The near-yrast states in ⁹³Mo were interpreted using the weak-coupling picture of a d_5/2 neutron to a neutron magic core nucleus ⁹²Mo.     

Poly(N-isopropylacrylamide) microparticles produced by radiation pressure of a focused laser beam: a structural analysis by confocal Raman microspectroscopy combined with a laser-trapping technique

We developed a confocal Raman microspectroscopy system combined with a laser trapping technique and applied it to aqueous solutions (H(2)O and D(2)O) of poly(N-isopropylacrylamide) (PNIPA), which is well-known as a representative thermo-responsive polymer, i.e., phase transition/separation between coiled and globular states. By introducing a near-infrared (1064 nm) laser beam into a microscope, PNIPA microparticles were produced at the focused spot of the laser beam, both in H(2)O and D(2)O. By using the present system, we succeeded in obtaining the Raman spectra of PNIPA in the coiled and globular states over a wide wavenumber region (800-3500 cm(-1)) for the first time. For the D(2)O solutions (in which the photothermal effect is negligible and hence the microparticles should be produced purely by the effect of radiation pressure), some significant differences were observed in the Raman spectra for the coiled state, in the globular state, and for laser induced microparticles. By analyzing these spectra in detail, we revealed that the structure of the laser-induced microparticles was analogous to that in the globular state. We also discuss the fundamental mechanism underlying the transformation of the higher order structure of a polymer by radiation pressure.     

High pressure Raman study of bromine and iodine: soft phonon in the incommensurate phase

A new phase of solid bromine was discovered at a pressure region above 80 GPa by Raman scattering experiments with a diamond anvil high-pressure cell. This phase was found to be the same as the iodine phase V with an incommensurate structure [Nature (London) 423, 971 (2003)] which appears between the molecular phase I and the monatomic phase II. In the incommensurate phases of both bromine and iodine, Raman active soft modes were clearly found in the low frequency region. The data suggest that the monoatomic phase II occurs above 30 and 115 GPa for iodine and bromine, respectively.     

Surface-emitted terahertz-wave difference-frequency generation in two-dimensional periodically poled lithium niobate

We report on the demonstration of surface-emitted terahertz- (THz-) wave difference-frequency generation from two-dimensional (2D) periodically poled lithium niobate (PPLN). The two orthogonal periodic structures individually compensate for both the phase mismatch of the launched lasers and the generated THz wave. Tunable 1.5-1.8 THz wave generation with a bandwidth of 10-GHz was obtained by use of two 2D PPLN crystals. We also confirmed that THz waves were simultaneously generated into two opposite directions, which suggests the possibility of higher THz-wave output power.     

Synthesis of adamantane derivatives—XXX: Synthesis of some adamantane spiro heterocycles by utilizing ionic- and cycloadditions

Synthesis and some reactions of adamantane spiro heterocycles such as aziridine, oxaziridine, azetidine and 1,2-diazetidine derivatives have been described.The 1,3-dipolar cycloadditions of methyleneadmantane (2) and adamantylidenecyanoacrylate (14) have also been reported as a facile route to some 5-membered adamantane spiro heterocycles.     

Anomalous magnetotransport phenomena in θ-(BEDT-TTF)2I3

Anomalous magnetotransport phenomena have been observed in θ-(BEDT-TTF)₂I₃ crystals at temperatures below 15 K. The magnetoresistance M : (1) is a linear function of the magnetic field H, (2) is not affected by the angle between the electric current and the magnetic field, (3) but depends on the magnetic field orientation with respect to the crystal axis. Magnetoresistance is expressed as M = (aH²_a + bH²_b + cH²_c)₀^-3/2/H in terms of H = (H_a, H_b, H_c), the zero field resistivity ₀, and parameters a, b, and c which are independent of temperature and magnetic field. We have found that b a > c. Magnetoresistance up to 40 is observed for H = 7T along the b-axis at T = 1.5K.     

A structure-biological activity study based on cluster analysis and the nonlinear mapping method of pattern recognition

Cluster analysis is used in a study of structure—activity relationships of biologically active compounds. A hierarchal clustering technique was applied to 29 typical antibiotics using 27 antibacterial activities. These antibiotics were of various types; penicillins, cephalosporins, aminoglycosides, macrolides, tetracyclines, and peptides. The result was obtained as a branching tree diagram. The technique allowed the antibiotics to be distributed into 6 clusters, each cluster mostly consisting of compounds with a similar structure. Nonlinear mapping was used to display the 27-dimensional data structure of the antibiotics. The nonlinear map was compared with the clusters obtained by cluster analysis.