Experimental studies of microwave amplification in the ion-focusedregime

Studies of microwave amplification with an in-focused electron beam drawn from an induction injector are reported. A free-electron laser (FEL) operating at 9.4 GHz and employing ion-focusing within the interaction region has achieved power in excess of 30 MW at 9.4 GHz, with a beam energy of 0.8 MeV and current of 0.7 kA. Peak gain is 20 dB/m, with no saturation after 15 wiggler periods. Also reported are the first evolution and detuning data for an ion-channel laser/maser (ICL). Two shortcomings of the prematurely halted ICL studies are poor frequency discrimination and a large axial plasma gradient. Prospects for operation with an upgraded 1.6 MeV accelerator are discussed     

Linear optical switching in a FLC/waveguide composite device

A fast electrooptic modulation in a polymer waveguide using a ferroelectric liquid crystal has been proposed. In this device, the surface stabilized ferroelectric liquid crystal and the soft mode ferroelectric liquid crystal are used as an active material on the passive polymer waveguide, and electrooptic switching is realized by controlling the total reflection at the polymer waveguide-liquid crystal interface. The response time is of the order of several microseconds. The analogue electrooptic modulation in the waveguide is realized using the field induced linear molecular tilt of the electroclinic effect in the soft mode ferroelectric liquid crystal.     

Anti-inflammatory effect of Zingiber cassumunar Roxb. and its active principles.

The present study was carried out to elucidate the anti-inflammatory effect of the methanol extract obtained from the rhizomes of Zingiber cassumunar Roxb. and its active principles. The methanol extract was partitioned between ether and water, and then the ether-soluble fraction was extracted with n-hexane. The n-hexane-soluble fraction was chromatographed and part of the fraction was rechromatographed by silica gel column. Three compounds were isolated from the n-hexane-soluble fraction and the chemical structures of these compounds were identified as (E)-1-(3,4-dimethoxyphenyl)but-1-ene, (E)-1-(3,4-dimethoxyphenyl)butadiene and zerumbone. The anti-inflammatory activity of these fractions was investigated on carrageenin-induced edema in rats, as well as on acetic acid-induced vascular permeability and writhing symptoms in mice. The methanol extract (p.o.) showed both anti-inflammatory activity and analgesic activity. These activities shifted successively to ether-soluble and n-hexane-soluble fractions and to (E)-1-(3,4-dimethoxyphenyl)but-1-ene. These results suggest that the anti-inflammatory action and analgesic action of Zingiber cassumunar is the result of the (E)-1-(3,4-dimethoxyphenyl)but-1-ene that it contains.     

5-Fluorouracil derivatives. XX. Synthesis and antitumor activity of 5'-O-unsaturated acyl-5-fluorouridines

Various kinds of 5'-O-unsaturated acyl 5-fluorouridines were synthesized to obtain 5-fluorouridine derivatives with low toxicity and high antitumor activity. Antitumor activity of the compounds against L-1210 leukemia in mice was examined, and the 5'-O-4-pentenoyl derivative showed the highest antitumor activity.     

THE CONFORMATIONAL ANALYSIS AND PHOTOISOMERIZATION OF RETINOCHROME ANALOGS WITH POLYENALS

Abstract— 3, 7-Dimethyl-2, 4, 6, 8, 10-dodecapentaenal was synthesized for reconstitution of the retinochrome analog. Its opsin shift was 1000 cm ¹ smaller than that of native retinochrome, whose chromophore contains the same number of double bonds. The conformational change from 6-s-trans to 6-s-cis , as figured in a retinal molecule, plays an important role in the formation of the retinochrome analog, based on the estimation of opsin shifts for retinal analogs locked in the 6-s conformation. Thus the conformation of the 6–7 single bond in the native retinochrome was suggested to be 6 -cis . Analysis of the circular dichroic spectra of retinochrome analogs revealed that the 6-s conformation is independent of the appearance of the β-band. The stereoselectivity in the photoisomerization of the retinal analogs by a retinochrome template depends on the hydrophobic binding in the region of the β-ionone ring.     

Electronic structure and magnetic properties of small manganese oxide clusters

To investigate the electronic structure and magnetic properties of manganese oxide clusters, we carried out first-principles electronic structure calculations for small MnO clusters. Among various structural and magnetic configurations of the clusters, the bulklike [111]-antiferromagnetic ordering is found to be favored energetically, while the surface atoms of the clusters exhibit interesting electronic and magnetic characteristics which are different from their bulk ones. The distinct features of the surface atoms are mainly attributed to the reduction of Mn coordination numbers and the bond-length contractions in the clusters, which may serve as a key factor for the understanding of physical and chemical properties of magnetic oxide nanoparticles.     

Multitracer study on permeation of rare earth elements through a supported liquid membrane

Separation by means of supported liquid membranes is a useful method for the preparation and preconcentration of radioactive nuclides. The permeation of rare earth elements through a bis(2-ethylhexyl) hydrogen phosphate-decalin membrane supported on a microporous polytetrafluoroethylene sheet was studied using a multitracer containing radioactive nuclides of Sc, Zr, Nb, Hf, Ce, Pm, Gd, Yb, and Lu. Permeation rates of these elements from feed solutions of various acidity to receiving solutions of 0.5 mol·dm⁻³ HCl were determined simultaneously. The feed solution at pH 1.4 gave the highest permeation rate for Ce, Pm, and Gd, amounting to about 95% of permeation for Ce and Pm, 80% for Gd, and 10% for Yb in 21 h. Scandium, Zr, Nb, Hf, and Lu were not transported at all from the feed solution. Permeation rates of Yb and Lu from the feed solution at pH 1.4 to receiving solutions of 0.75, 1.0, 2.3, and 4.0 mol·dm⁻³ HCl increased with the concentration. The results obtained indicate that the light rare earth elements can be separated from the heavy ones by this method.     

Determination of total nitrogen content, pH, density, refractive index, and brix in Thai fish sauces and their classification by near-infrared spectroscopy with searching combination moving window partial least squares

Near-infrared (NIR) transflectance spectra in the region of 1100-2500 nm were measured for 100 Thai fish sauces. Quantitative analyses of total nitrogen (TN) content, pH, refractive index, density and brix in the Thai fish sauces and their qualitative analyses were carried out by multivariate analyses with the aid of wavelength interval selection method named searching combination moving window partial least squares (SCMWPLS). The optimized informative region for TN selected by SCMWPLS was the region of 2264-2428 nm. A PLS calibration model, which used this region, yielded the lowest root mean square error of prediction (RMSEP) of 0.100% w/v for the PLS factor of 5. This prediction result is significantly better than those obtained by using the whole spectral region or informative regions selected by moving window partial least squares regression (MWPLSR). As for pH, density, refractive index and brix, the 1698-1722, and 2222-2258 nm regions, the 1358-1438 nm region, the 1774-1846, and 2078-2114 nm regions, and the 1322-1442, and 2000-2076 nm regions were selected by SCMWPLS as the optimized regions. The best prediction results were always obtained by use of the optimized regions selected by SCMWPLS. The lowest RMSEP for pH, density, refractive index and brix were 0.170, 0.007 g cm(-3), 0.0079 and 0.435 degrees Brix, respectively. Qualitative models were developed by using four supervised pattern recognitions, linear discriminant analysis (LDA), factor analysis-linear discriminant analysis (FA-LDA), soft independent modeling of class analog (SIMCA), and K neareat neighbors (KNN) for the optimized combination of informative regions of the NIR spectra of fish sauces to classify fish sauces into three groups based on TN. All the developed models can potentially classify the fish sauces with the correct classification rate of more than 82%, and the KNN classified model has the highest correct classification rate (95%). The present study has demonstrated that NIR spectroscopy combined with SCMWPLS is powerful for both the quantitative and qualitative analyses of Thai fish sauces.