Porphyrin-Catalyzed Oxidation of Trichlorophenol

Porphyrin-metal complexes are potentially useful to catalyze redox reactions, which convert toxic and biologically recalcitrant compounds to compounds that are less toxic and more amenable to biotreatment. Porphyrins, in the absence of proteins as in ligninases, peroxidases, and oxidases, are potentially more robust than enzymes and microbial cultures in the treatment of inhibitory substances. 2,4,6-Trichlorophenol was used as a model compound for chlorinated phenols and as a substrate for various porphyrin-metal complexes acting as oxidation catalysts. t-Butyl hydroperoxide was the oxidizing agent. TCP was shown to be at least partially dechlorinated and the aromatic ring broken in reaction products. All porphyrins exhibited saturation kinetics with regard to the initial TCP concentration in reaction mixtures. Electron-withdrawing substituents on the porphyrins were observed to increase stability of the catalysts to inactivating ring-centered oxidation.     

Ab initio calculation of vibrational frequencies of GexPxS1−2x glass

The vibrational frequencies of GeS₄, GeP₄, Ge₂S₆, GeP₃, Ge₃P, Ge₂P₂, P₂S₂, P₃S, P₄S₃, α-P₄S₄, β-P₄S₄, α-P₄S₅, β-P₄S₅, P₄S₇, P₄S₉ and P₄S₁₀ are theoretically computed from the first principles. The Raman frequencies of Ge_xP_xS_1−2x glass are obtained for x varying from 0.05 to 0.019. The computed fundamental frequencies of clusters are compared with those experimentally found. In this way, we are able to identify the vibrating clusters in the real glass. The clusters identified in the real glass are found to be Ge₂P₂, P₄S₃, α-P₄S₄, β-P₄S₄, β-P₄S₅, P₄S₇, P₄S₉, β-P₄S₅, Ge₂S₆, Ge₃P.     

Controlled electrophoretic deposition of uniquely nanostructured star polymer films

The controlled electrophoretic deposition of polystyrene/divinylbenzene (PS/DVB) star polymer films from a colloidal suspension is reported. Liquid suspensions, containing the PS/DVB star polymer, were prepared by injecting a dichloromethane (DCM) solution of the star polymer into a stratified liquid combination of hexane and DCM. A variety of hexane/DCM volume ratios were examined to identify the optimal solution conditions for electrophoretic deposition; thin films were produced from both unmixed and well-mixed hexane/DCM suspensions. Unmixed suspensions yielded spatially separated thin films, deposited in a controlled fashion, that were dependent on the polarity of the corresponding electrode. Films on the positive electrode differed in thickness, microstructure, and appearance from those formed on the negative electrode. In contrast, films produced from well-mixed hexane/DCM suspensions deposited uniformly across only the negative electrode. Atomic force microscopy studies revealed nanostructured surface morphologies that were unique to each of these films. Additionally, these microscopy studies shed light on the possible conformations of star polymers adsorbed on a surface. By controlling the composition and the mixing state of the solution and by controlling the bias of electrodes, we achieved controlled deposition of star polymer films with a specific nanostructure. These nanostructured films may have broad use in optical and biological device applications.     

Rapid Estimation of Octanol–Water Partition Coefficient for Triazole Fungicides by MEKC with Sodium Deoxycholate as Surfactant

A rapid estimation of octanol–water partition coefficient (log P _ow) was developed for triazole fungicides by micellar electrokinetic chromatography (MEKC). Five standard compounds with known log P _ow values from 2.9 to 4.3 (cyproconazole, bromuconazole, epoxiconazole, bitertanol and difenoconazole) were used for constructing the calibration curve of the log P _ow against the MEKC retention factor, log k. A linear relationship was achieved between log P _ow and log k, in the MEKC system containing 40 mM sodium deoxycholate (SDC) and 4 mM borate buffer at pH 9.3, with a correlation of determination, r ² = 0.9905. The log P _ow values of four test compounds of triazole fungicides (triadimenol, myclobutanil, propiconazole and penconazole) were calculated based on the log k values measured by MEKC and the slope and intercept of the calibration curve. This MEKC method can give good estimation of the log P _ow of the four test compounds of triazole fungicides with the differences between the literature log P _ow values and estimated log P _ow from the MEKC method were from 0.15 to 0.23 log units.     

Phenylethyl Glycosides from Globularia alypum Growing in Turkey

From the leaves of Globularia alypum, three new phenylethyl glycosides, namely galypumosides A (=2‐(3,4‐dihydroxyphenyl)ethyl O‐α‐rhamnopyranosyl‐(1→3)‐4‐O‐[(E)‐caffeoyl]‐6‐O‐[(E)‐p‐coumaroyl]‐β‐glucopyranoside; 1 ), B (=2‐(3,4‐dihydroxyphenyl)ethyl O‐α‐rhamnopyranosyl‐(1→3)‐4‐O‐[(E)‐caffeoyl]‐6‐O‐[(E)‐feruloyl]‐β‐glucopyranoside; 2 ), and C (=2‐(3,4‐dihydroxyphenyl)ethyl O‐α‐rhamnopyranosyl‐(1→3)‐4‐O‐[(E)‐caffeoyl]‐6‐O‐menthiafoloyl‐β‐glucopyranoside; 3 ), were isolated, together with two known phenylethyl glycosides, calceolarioside A and verbascoside. Eight iridoid glucosides, catalpol, globularicisin, globularin, globularidin, globularinin, globularimin, lytanthosalin, and alpinoside, a flavon glycoside, 6‐hydroxyluteolin 7‐O‐sophoroside, a lignan glycoside, syringaresinol 4′‐O‐β‐glucopyranoside, and a phenylpropanoid glycoside, syringin, were also obtained and characterized. The structures of the isolates were elucidated on the basis of 1D‐ and 2D‐NMR experiments as well as HR‐MALDI‐MS.     

Fiber Optic Excitation of Silicon Microspheres in Amorphous and Crystalline Fluids

ABSTRACT

This study investigates the optical resonance spectra of free-standing monolithic single crystal silicon microspheres immersed in various amorphous fluids, such as air, water, ethylene glycol, and 4-Cyano-4’-pentylbiphenyl nematic liquid crystal. For the various amorphous fluids, morphology-dependent resonances with quality factors on the order of 10⁵ are observed at 1428 nm. The mode spacing is always on the order of 0.23 nm. The immersion in various amorphous fluids affects the spectral response of the silicon microsphere and heralds this technique for use in novel optofluidics applications. Even though the nematic liquid crystal is a highly birefringent, scattering, and high-index optical medium, morphology-dependent resonances with quality factors on the order of 10⁵ are observed at 1300 nm in the elastic scattering spectra of the silicon microsphere, realizing a liquid-crystal-on-silicon geometry. The relative refractive index and the size parameter of the silicon microsphere are the parameters that affect the resonance structure. The more 4-Cyano-4’-pentylbiphenyl interacting with the silicon microsphere, the lower the quality factor of the resonances is. The more 4-Cyano-4’-pentylbiphenyl is interacting with the silicon microsphere, the lower the mode spacing Δλ of the resonances is. The silicon microspheres wetted with nematic liquid crystal can be used for optically addressed liquid-crystal-on-silicon displays, light valve applications, or reconfigurable optical networks.     

Performance evaluation of IDW,Kriging and multiquadric interpolation methods in producing noise mapping: A case study at the city of Isparta,Turkey

In order to produce an accurate noise map of a city or a region, it is necessary to make noise measurements at certain locations and these measurements must be modeled with the most suitable mathematical algorithm. A homogeneous and representative distribution of the noise measurement points is the first key factor in the production of sound noise maps. The second key element is the calculation of the noise values of gridding points based on noise measurement points according to the selected mathematical calculation method and the generation of maps according to these gridding points. In this study, a noise map of the Isparta city center and its periphery was produced using inverse distance weighted (IDW), Kriging and multiquadric interpolation methods with different parameters and four grid resolution. Then, the influence of parameter selection for each method was investigated in themself by taking into account grid resolution, namely 10 ∗ 10 m, 50 ∗ 50 m, 100 ∗ 100 m and 200 ∗ 200 m, and the performance of three method with 50 ∗ 50 m grid resolution were compared with each other. In addition, the noise mapping of the city of Isparta were produced by Kriging method with respect to maximum, average and minimum noise data and they were evaluated by considering the national environmental noise thresholds.     

Quantum‐Transport Characteristics of a p–n Junction on Single‐Layer TiS3

By using density functional theory and non‐equilibrium Green′s function‐based methods, we investigated the electronic and transport properties of a TiS₃ monolayer p–n junction. We constructed a lateral p–n junction on a TiS₃ monolayer using Li and F adatoms. An applied bias voltage caused significant variability in the electronic and transport properties of the TiS₃ p–n junction. In addition, the spin‐dependent current–voltage characteristics of the constructed TiS₃ p–n junction were analyzed. Important device characteristics were found, such as negative differential resistance and rectifying diode behaviors for spin‐polarized currents in the TiS₃ p–n junction. These prominent conduction properties of the TiS₃ p–n junction offer remarkable opportunities for the design of nanoelectronic devices based on a recently synthesized single‐layered material.     

On the well-posedness of the Holm-Staley b-family of equations

In this paper we consider the Holm-Staley b-family of equations in the Sobolev spaces H^s(?) for s>3/2. Using a geometric approach we show that, for any value of the parameter b, the corresponding solution map,u(0)?u(T ), is nowhere locally uniformly continuous.