Photonic Crystal Fibers

By offering greatly enhanced control of light compared to conventional step-index structures, photonic crystal fibres are radically improving the performance of linear and nonlinear fibre devices, including gas-Raman cells, super-continuum generators, soliton systems and cladding-pumped lasers.     

JT-60U装置温度分布剖面不变性的实验研究

在一系列H模放电条件下，建立了一个旨在研究等离子体温度分布剖面不变性的数据库。介绍了数据库建立过程中要解决的关键问题和所用软件，对等离子体温度分布剖面不变性及芯部约束与边缘参数的关系进行了研究。     

Eigenvalues of the Boltzmann collision operator for binary gases: Mass dependence

Eigenvalues of the Boltzmann collision operator are calculated versus mass ratio with two different methods. One method involves the expansion of the eigenfunctions in speed polynomials, whereas with the second method the eigenfunctions are evaluated at discrete points based on a particular gaussian quadrature rule. The discrete ordinate method proved to be superior provided the mass ratio was neither too large nor too small. The approach of the eigenvalues to the continuum boundary was also studied for several mass ratios.     

Determination of the lifetime of the mercury 63P1 state

A pulsed tunable dye laser was used for a high resolution experimental study of mercury fluorescence from the 6³P₁ state. The output of the dye laser was frequency doubled into the 253.7 nm region using a potassium penta-borate crystal. Exponential decays were observed for each of the five individual components of the hyperfine structure separately and the effects of the trapping of resonance radiation on the observed lifetime of the 6³P₁ state of mercury were investigated for each resolvable component. Within experimental error, the natural radiative lifetime of the 6³P₁ state was found to be independent of the hyperfine component irradiated and a value of 122±2 nsec was obtained, consistent with results found by other methods.     

Use of a large quartz spectrograph for the determination of thorium, yttrium and the rare earths in silicates

Studies were carried out on the optimum conditions for the successful use of a large quartz spectrograph for the determination of thorium, yttrium and the rare earths in silicate rocks. The best line-to-background ratios were achieved by arcing samples in a matrix of 4 % sodium chloride in carbon powder. An atmosphere of 20 % argon and 80% oxygen was used to reduce background and eliminate cyanogen band interference. An anion-exchange procedure was used to separate the rare earths from other elements. The resultant enrichment allowed use to be made of less sensitive rare earth lines in the ultraviolet end of the spectrum where the spectrographic dispersion is greater. Line interferences were studied and necessary corrections for these interferences were calculated. The technique was tested by analysing the standard rocks, G-1, W-1 and CAAS syenite. Good agreement with recommended values was obtained.     

Effect of Added Alcohols or Carboxylate on the Preparation of 7,7-Dichlorobicyclo[4.1.0]Heptane

The phase transfer base catalyzed generation of dichlorocarbene and its subsequent addition to cyclohexene is markedly influenced by the introduction of an alcohol or carboxylate. Generally an added alcohol will facilitate the reaction while carboxylate ion retards the reaction.     

Towards identification of traditional European and indigenous Australian paint binders using pyrolysis gas chromatography mass spectrometry

We report a pyrolysis GC–MS method capable of analysing Indigenous Australian and European binders typically used in the manufacture of culturally important painted works. Eleven different traditional European binders and ten different Indigenous Australian binders were examined. The method allows discrimination between highly complex and impure lipid, resin, polysaccharide, wax, and protein-based binders. Each was found to have characteristic pyrolysis products that were unique to the binder material, demonstrating the potential for differentiation of these binders on Australian Aboriginal artworks towards identification and conservation of cultural heritage.     

Phase transfer catalysts anchored to polystyrene

Quarternary phosphonium and ammonium salts attached to polystyrene resins by short (2 - 3 atom) carbon chains are highly active phase transfer catalysts for a variety of nucleophilic substitution reactions.