Neutral radical detection in silane glow-discharge plasma using coherent anti-stokes raman spectroscopy

RF glow discharges of silane have been investigated using CARS technique, and a weak signal assigned to the ν₁ Q-band of SiH₂ has been observed at around 2030 cm^?1 for the first time. The number density of SiH₂ in the plasma has been estimated and is discussed in relation to the magnitude of SiH₄ dissociation rate independently determined also by CARS.     

Optical feedback effect on bistable laser diodes

The optical feedback effect on multi-section bistable laser diode characteristics, especially on light/current hysteresis, has been studied. A decrease in the bistable laser diode hysteresis width under optical feedback was observed for the first time. A theoretical analysis has been carried out by solving carrier density rate equations, combined with the light-field equation. The analysis shows that the observed hysteresis width decrease is due to the phase detuning, which is governed by the difference between the values of the α-parameters (line-width enhancement factors) in the gain section and the loss section.     

Essential spectrum of linearized operator for MHD plasma in cylindrical region

Linearized operators for ideal magnetohydrodynamics related to the plasma confinement are considered for a cylindrical geometry. The essential spectrum for the Fourier decomposed operator is determined by an analysis of its inverse. In particular, the mathematically rigorous treatment of the magnetic axis is presented.

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Résumé On considère les opérateurs linéarisés de la magnetohydrodynamique idéale en géométrie cylindrique par rapport au confinement du plasma. Le spectre essential pour l'opérateur Fourierdécomposé est déterminé par l'analyse de son inverse. En particulier, on présente le traitement mathématiquement rigoureux de l'axe magnétique.

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This work was supported by the Swiss National Foundation of Sciences during the stay of the author at the Swiss Federal Institute of Technology. Lausanne.     

Effect of solid walls on spontaneous wave formation at water/oil interfaces

The regulation of spontaneous waves at water/oil interfaces was investigated, focusing on effects of materials and sizes of containers. Trimethylstearylammonium chloride was dissolved in an aqueous phase. Nitrobenzene with potassium iodide and iodine was used as an organic phase. Rotation of interfacial waves with almost triangular shape was observed only in containers made of glass. The nature of interfacial waves is sensitive to container size. There was no interfacial wave in PFA (Teflon) containers. However, when a glass plate was soaked vertically to the interface, oscillation of contact angles of water/oil interfaces to glass plates was observed. The oscillation generated wave propagation along the plate. Dynamic interfacial tension was measured by Wilhelmy method and the pendant drop technique. Results with the Wilhelmy method in small glass containers exhibited spontaneous oscillation. However, oscillations in dynamic interfacial tension were not observed for other cases, i.e., the Wilhelmy method for large glass containers, for PFA containers, and for the pendant drop technique. It was concluded that all nonlinear behavior such as wave generation and apparent tension oscillation could be attributed to the effect of the sidewalls of container on the adsorption/desorption kinetics of the surfactant. We propose a possible scenario which can explain all of the qualitative features of the present experimental findings.     

Precolumn derivatization reagents for high‐speed analysis of amines and amino acids in biological fluid using liquid chromatography/electrospray ionization tandem mass spectrometry

A rapid analytical method for amines and amino acids was developed, involving derivatization with the novel reagent 3‐aminopyridyl‐N‐hydroxysuccinimidyl carbamate (APDS), followed by reversed‐phase high‐performance liquid chromatography and electrospray ionization tandem mass spectrometry (HPLC/ESI‐MS/MS). More than 100 different analytes with amino groups, including amino acids in biological fluids such as mammalian plasma, could be measured within 10 min. The analytes were easily derivatized with APDS under the mild conditions. Selective reaction monitoring of ESI‐MS/MS in positive mode was carried out to include the transitions of all of the protonated molecular ions of analytes derivatized with APDS to the common fragment at m/z 121, which was derived from the amino pyridyl moiety of the reagent. We evaluated the retention time precision, the quantification limits, the linearity, the intra‐ and inter‐day precisions and the accuracy of 22 typical amino acids found in biological fluids, by analyzing a standard amino acid mixture and rat plasma. The intra‐day relative standard deviations (RSDs) of the retention times of the 22 amino acids and their internal standards were within 0.9% and the inter‐day RSDs were less than 1.1%, except for asparagines, with an RSD of 1.9%. The intra‐day and inter‐day RSDs of amino acid analyses in rat plasma were within 8.0% and 4.5%, respectively. The method, which facilitates the amino acid analysis of more than 100 samples in a day, represents an alternative to traditional amino acid analysis techniques, such as chromatography using postcolumn derivatization by ninhydrin. Copyright © 2009 John Wiley & Sons, Ltd.     

Development of Scanning Near-Field Optical Microscope Working under Cryogenic Temperature and Strong Magnetic Field

We report on the development of a cantilever-based scanning near-field optical microscope (SNOM) working in an extreme environment, at cryogenic temperature around 10 K and under strong magnetic field up to 7 T. We designed a new optical system based on an infinite conjugate microscope, which extracts the near-field signal from a small aperture through a narrow chamber into free space as collimated light. Using this system, we successfully measured near-field and topographical images of a metal-hole sample simultaneously. Combining the local optical accessing technique with the external control of the electronic state, this SNOM system will be a powerful tool to study optical properties of semiconductor nanostructures.     

Algorithms for finding a Kth best valued assignment

We consider a new problem, the Kth best valued assignment problem. Given a bipartite graph G and a cost vector w on its edge set, this is the problem of finding a perfect matching M_k in G such that there exist perfect matchings M₁,…,M_K−1 satisfying w(M₁) < < w(M_K−1) < w(M_K), and w(M_K) < w(M) for all perfect matchings M with w(M) ≠ w(M₁),…,w(M_K). Here w(M) denotes the sum of costs of edges in M. In this paper, we propose two algorithms for solving this problem and verify the efficiency of our algorithms by our preliminary computational experiments.     

3-epicabraleahydroxylactone and other triterpenoids from camellia oil and their inhibitory effects on Epstein-Barr virus activation

The structure of a triterpenoid isolated from the nonsaponifiable lipid (NSL) of the seed oil of the camellia (Camellia japonica L.; Theaceae) was established to be (20S)-3beta-hydroxy-25,26,27-trisnordammaran-24,20-olide (1; 3-epicabraleahydroxylactone) on the basis of spectroscopic and chemical methods. Six other triterpenoids isolated from the NSL were identified as 3-epicabraleadiol (2), ocotillol II (3), ocotillol I (4), dammarenediol II (5), (20R)-taraxastane-3beta,20-diol (6), and lupane-3beta,20-diol (7). Upon evaluation of the seven triterpenoids (1-7) with respect to their inhibitory effects on the induction of Epstein-Barr virus early antigen (EBV-EA) by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells, three compounds (5-7) showed potent inhibitory effects against EBV-EA induction (IC(50) values of 277-420 mol ratio/32 pmol TPA).     

New insights in muon-catalyzed dd fusion by using ortho-para controlled solid deuterium

For the first time, we observed the dependence of the ddmu formation rate and the dmu hyperfine-transition rate on the ortho-para state in muon-catalyzed fusion in the solid D2 state, and found that the effect is even opposite to a recent theoretical prediction. We also determined the back-decay rate and the hyperfine-transition rate via scattering in solid state by using the ortho-para dependence. A theory to describe properly our experimental result is called for to understand the nature of muon-catalyzed fusion in the solid state.