Wavelength and power monitoring of DWDM systems using scanning F–P filter calibrated with a F–P laser

A novel technique to overcome the long-term drift and hysteresis of a scanning Fabry–Perot filter was developed and applied to wavelength and power monitoring of DWDM system. By using the comb peaks generated by a temperature-stabilized, near threshold-biased Fabry–Perot diode laser as wavelength reference for the scanning Fabry–Perot filter, wavelength and power measurement accuracy of better than ±10 pm and 0.2 dB, respectively, were achieved.     

Roles of rhenium diimine complexes as metal‐ion probes and photosensitizers in functional polyurethanes

Polyurethanes incorporated with rhenium diimine complexes were synthesized. The polymers exhibited interesting morphologies and solution properties. Results from gel permeation chromatography suggested the formation of polymer aggregates in solutions. The polymers could act as probes for metal ions. The addition of metal ions to polymer solutions led to significant changes in the electronic absorption properties of the polymer solutions. This was attributed to the interactions between the polyether moieties and metal ions. The metal complexes could also act as efficient photosensitizers. After doping with charge‐transport viologens, the photoconductivity of the polymers was greatly enhanced. The experimental quantum efficiency was simulated with Onsager's theory. The thermalization distances and the primary yields were typically 12–14 Å and 10^?3, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1708–1715, 2003     

A boundary element method for the calculation of noise barrier insertion loss in the presence of atmospheric turbulence

Atmospheric turbulence is an important factor that limits the amount of attenuation a barrier can provide in the outdoor environment. It is therefore important to develop a reliable method to predict its effect on barrier performance. The boundary element method (BEM) has been shown to be a very effective technique for predicting barrier insertion loss in the absence of turbulence. This paper develops a simple and efficient modification of the BEM formulation to predict the insertion loss of a barrier in the presence of atmospheric turbulence. The modification is based on two alternative methods: (1) random realisations of log-amplitude and phase fluctuations of boundary sources and (2) de-correlation of source coherence using the mutual coherence function (MCF). An investigation into the behaviours of these two methods is carried out and simplified forms of the methods developed. Some systematic differences between the predictions from the methods are found. When incorporated into the BEM formulation, the method of random realisations and the method of MCF de-correlation provide predictions that agree well with predictions by the parabolic equation method and by the scattering cross-section method on a variety of thin barrier configurations.     

The effect of solvents on the extraction of lanthanoids with 18-crown-6 and trichloroacetate

The effect of solvents on the extraction of lanthanoids with 18-crown-6 and trichloroacetic acid was investigated for the solvents, 1,1,-dichloroethane, 1,2-dichloroethane, 1,1, 2,2-tetrachloroethane, chloroform, di-2-chloroethyl ether, and methylene chloride. Distribution coefficients (25 °C) normalized to the water solubility (wt./vol.) in the solvents correlated to the polarizability index (^*) for La³⁺, Ce³⁺, Pr³⁺, and Nd³⁺ with r values=0.93,0.93,0.95, and 0.98, respectively. The distribution coefficients for Nd³⁺ also correlated with the Hildebrand solubility parameter () (r=0.98). These correlations agree with the literature that for large ions, the extraction thermodynamic properties correlate with the polarizability index and Hildebrand solubility parameter.     

Ultraviolet photolysis of CH2I2 in methanol: O-H insertion and HI elimination reactions to form a dimethoxymethane product

Ultraviolet photolysis of low concentrations of CH2I2 in methanol solution found that CH2I2 is converted into dimethoxymethane and some H+ and I- products. Picosecond time-resolved resonance Raman (ps-TR3) experiments observed that the isodiiodomethane (CH2I-I) photoproduct decayed faster as the concentration of methanol increases, suggesting that isodiiodomethane is reacting with methanol. Ab initio calculations indicate isodiiodomethane is able to react with methanol via an O-H insertion/HI elimination to form an iodoether (ICH2-O-CH3) and HI products. The iodoether can then further react via another O-H insertion/HI elimination reaction to form the dimethoxymethane (CH3-O-CH2-O-CH3) observed in the photochemistry experiments. A reaction mechanism consistent with these experimental and theoretical observations is proposed.     

Comparison of the dehalogenation of dihalomethanes (CH2XI, where X = Cl, Br, I) following ultraviolet photolysis in aqueous and NaCl saltwater environments

The ultraviolet photolysis of low concentrations of CH(2)XI (X = Cl, Br, I) were investigated in water and saltwater solutions by photochemistry and picosecond time-resolved resonance Raman spectroscopy. Photolysis in both kinds of solutions formed mostly CH(2)(OH)(2) and HI and HX products. However, photolysis of the CH(2)XI molecules in saltwater resulted in production of some CH(2)XCl products not observed in aqueous solutions without salt present. The appearance of these new products in saltwater solutions is accompanied by a decrease in the amount of CH(2)(OH)(2), HI, and HX products compared to photolysis in aqueous solutions without salt present. The possible implications for photolysis of CH(2)XI and other polyhalomethanes in seawater and other salt aqueous environments compared to nonsaltwater solvated environments is briefly discussed.     

Synthesis,characterization, and theoretical studies of group 4 amido hydrotris(pyrazolyl)borate complexes

Titanium and zirconium amido complexes containing a hydrotris(pyrazolyl)borate (Tp) or hydrotris(3,5-dimethylpyrazolyl)borate (Tp*) ligand TpM(NMe(2))(3) (M = Ti, 1; M = Zr, 2) and Tp*M(NMe(2))(3) (M = Ti, 3; M = Zr, 4) were prepared by the reactions of M(NMe(2))(3)Cl (M = Ti, Zr) with sodium hydridotris(pyrazol-1-yl)borate and potassium hydridotris(3,5-dimethylpyrazol-1-yl)borate, respectively. The structures of 1, 2, and 4.CH(2)Cl(2) were determined by X-ray diffraction and show octahedral coordination geometry around the metal centers. Density functional theory calculations at the B3PW91 level were performed to understand the orientations and the rotational behavior of amido ligands in these metal complexes.     

Poly(ethylene glycol)-supported α,α,α-trifluoroacetophenone in dioxirane mediated alkene epoxidation reactions

Poly(ethylene glycol) (PEG) was used for the immobilization of α,α,α-trifluoroacetophenone and the utility of this supported ketone has been examined in dioxirane mediated epoxidation of alkenes. The PEG-ketone reagent was found to be an effective homogeneous catalyst for the epoxidation of a variety of alkenes in the presence of Oxone^® and was readily recovered from the reaction mixtures and reused.     

Traceless solid-phase synthesis of nitrogen-containing heterocycles and their biological evaluations as inhibitors of neuronal sodium channels

The preparation of pyrimidine-2-thione, pyrimidine-2-one, pyrimidine, and benzo[b][1,4]diazepine derivatives using traceless solid-phase sulfone linker strategy is described. Key steps involved are (i) sulfinate S-alkylation, (ii) sulfone anion alkylation with an epoxide, (iii) gamma-hydroxyl sulfone --> gamma-ketosulfone oxidation, and (iv) traceless product release by a one-pot elimination-cyclization process. Elimination-cyclization was carried out under basic conditions with thiourea, methyl thiourea, methyl urea, guanidine hydrochloride, benzamidine hydrochloride and ortho-phenylene diamine. Twenty-three compounds were prepared, and 14 of them were evaluated by the Batrachotoxin (BTX) radioligand binding assay for their binding affinity to neuronal sodium channels. Compound 7c was found to be a potential neuronal sodium channels blocker.     

Hydrogenation of olefins in supercritical CO(2) catalyzed by palladium nanoparticles in a water-in-CO(2) microemulsion

Nanometer-sized metallic palladium particles can be synthesized by hydrogen reduction of Pd2+ ions dissolved in the water core of a water-in-CO2 microemulsion. The Pd nanoparticles, stabilized by the micromeulsion and uniformly dispersed in the supercritical fluid phase, are effective catalysts for hydrogenation of olefins. Examples of rapid and efficient hydrogenation of water-soluble and CO2-soluble olefins catalyzed by the Pd nanoparticles in supercritical CO2 are given.