Raman-Nath diffraction by microparticles in water

In Raman-Nath diffraction by water, the intensities of even order light beams are selectively enhanced by suspension of microparticles. The diffracted beams remain for several seconds even after the ultrasonic oscillation stops. These phenomena are elucidated by assuming the laminar arrangement of micropaticles due to the ultrasonic wave.     

Synthesis and biological evaluation of optically active 3-H-1-carbacephem compounds

3-H-1-Carbacephem nuclei with or without a 2 alpha- or 2 beta-methyl group were prepared via 2 + 2 cycloaddition followed by intramolecular Horner-Emmons cyclization. Optically active 3-H-1-carbacephem compounds were efficiently prepared by employing a penicillin acylase-producing microorganism in two ways. That is, the 7-phenylacetamide of a racemic carbacephem nucleus was hydrolyzed enantioselectively with the enzyme to afford the optically pure nucleus, which was then acylated to give antimicrobial compounds. Alternatively, a racemic carbacephem nucleus was directly and enantioselectively phenylglycylated with the enzyme. 3-H-1-Carbacephem nuclei appeared to be better substrates for penicillin acylase than penam or cephem nuclei of natural origin. 3-H-1-Carbacephem compounds showed potent antimicrobial activity; compound 32a exhibited activity comparable to that of ceftizoxime, a cephem analog with the same acyl group. It is of interest that the 3-H-1-carbacephem compound turned out to have more potent antimicrobial activity than its 3-substituted methyl analog.     

Doppler-limited dye laser excitation spectrum of the C2 Swan band (v′ − v″ = 1 − 0)

The dye laser excitation spectrum of the Swan band (v′ ? v″ = 1 ? 0) has been observed with Doppler-limited resolution. The C₂ molecule was generated by the reaction of microwave discharge products of CF₄ with CH₄. The high sensitivity of laser excitation spectroscopy has enabled us to observe not only $\text{ΔΩ}\text{= 0}$ transitions, but also $\text{ΔΩ}\text{= ± 1}$ transitions and to determine molecular constants including the spin-orbit coupling constant for both the d³Π_g and a³Π_u states. The parameters thus obtained for a³Π_u were favorably compared with those previously obtained from the Ballik-Ramsay band. The present results on the d³Π_gv = 1 state were combined with those of an earlier Fourier spectroscopic study on the Swan band (v′ ? v″ = 0 ? 0) to derive equilibrium molecular constants for the d³Π_g state. The contributions of the spin-rotation interaction and the centrifugal correction for the spin-orbit coupling to the energy levels in a ³Π state have been discussed in detail.     

Determination of benzophenones in river-water samples using drop-based liquid phase microextraction coupled with gas chromatography/mass spectrometry.

In this study, a fast, simple and highly sensitive method that employs liquid phase microextraction (LPME)-GC/MS was developed to analyze trace benzophenones (BPs) in river-water samples. The tip of a 10-microl microsyringe filled with toluene (3 microl) was inserted into 2 ml of a river-water sample, and fixed at 5 mm below the water surface of the sample. A toluene droplet was made on the tip of the syringe, and extraction was conducted while agitating at 500 rpm for 15 min. After extraction, 2.0 microl of the extract was put into the syringe again, and directly introduced to GC/MS. The limits of detection (S/N = 3) and quantification (S/N >10) of BPs were 10 and 50 pg ml(-1), respectively. The results of a recovery test ranged over 93.3 - 101.1% (RSD, less than 10%; n = 6). The results of BPs determinations in the river-water samples showed that BPs (ND - 68.9 pg ml(-1)) were detected.     

Some remarks on finite full transformation semigroups

Communicated by J. M. Howie     

The two- and three-cluster fish bone model with saturation

The two- and three-cluster fish bone optical model with hard core correlations is derived from the corresponding resonating group model. The nuclear saturation effect is represented by three different features of inter-cluster interactions:i) by the non-local exchange potential,ii) by a reduced attraction in the region of overlapping clusters,iii) by an effective three-cluster potential. Comparability of the microscopic theory with phenomenological models is established by two off-shell transformations which orthogonalize function bases and avoid appearance of artificial three-body forces.     

Optical,structural, electrical and optoelectronic properties of hydrogenated amorphous Si1−x C x alloy thin films prepared by planar magnetron sputtering method

Amorphous Si_1–xC_x: H thin films were prepared by the rf magnetron sputtering method using a composite target of silicon and graphite. The dependence of the optical, structural, electrical, and optoelectronic properties on the carbon contentx was investigated, by measuring the optical absorption spectra, ir spectra, dark conductivity, photoconductivity and ESCA spectra. The optical gap was found to be unchanged with increasingx below about 0.6, in spite of the increase in the amount of the SiC bond. This is considered to be due to the formation of the carbon clusters. It is found that the photosensitivity shows a maximum at aboutx = 0.2, and is about one order of magnitude larger than the film withx = 0. This is related to the decrease in the dark conductivity, which is ascribed both to the formation of the SiC bond and to the reorganization of the defect-rich structure of sputter-deposited amorphous Si by the addition of about 20% carbon. The photoconductive effect was gradually lost in the range ofx above 0.6. In this range, the optical gap increases rapidly owing to the rapid increase of the SiC bond.     

Effect of the Fermi motion on nuclear structure functions and the EMC effect

The effect of the Fermi motion on nuclear structure function at largeQ ² (the EMC effect) is discussed in detail. We especially study its dependences on the kinematics of interaction, the 4-momentum transferQ ², the nucleon momentum distribution inside nucleus and the nuclear mass number. Moreover the structure function of¹²C at very largex such asx>1 is evaluated by only the nuclear Fermi motion, and related problems are discussed. We also point out a new dynamical mechanism expected to produce the depletion of valence quark inside nucleus for intermediatex, which does not encroach upon the conventional nuclear physics, and discuss it along the line of scaling hypothesis proposed by Daté et al.