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991.
Glasses in the system TeO2/Nb2O5/ZnO/CdS were studied with respect to the density, molar volume, refractive index, polarizability, molar refraction, metallization and third order non-linear optical susceptibility. The third order non-linear optical susceptibilities, χ(3), were measured using degenerate four-wave mixing (DFWM). The addition of CdS to TeO2-based glasses leads to increasing refractive as well as the non-linear refractive indices. The largest measured value of the third order non-linear optical susceptibility was 7.8 × 10?13 esu and has been found in the 90TeO2 · 5Nb2O5 · 5ZnO · 0.4 CdS glass. The non-linear optical susceptibility increased with increasing CdS-concentration. In order to estimate the third order non-linear optical susceptibility, the theoretical model of Lines and the empirical equation of Miller were used. 相似文献
992.
Nor Aiyyuhal Jemali Hasan Abu Kassim V. Radhika Devi Keshav N. Shrivastava 《Journal of Non》2008,354(15-16):1744-1750
We have used the density functional theory to make the models of GexSe1?x glass for which the energy is a minimum. The clusters, Ge2Se2, Ge2Se3, Ge3Se, Ge3Se2, Ge4Se, GeSe3, GeSe4, chain mode zig-zag Ge4Se3, corner sharing GeSe4, and edge sharing Ge2Se6, have been made successfully and their vibrational spectra have been calculated from the first principles. We are able to optimize the bond distances as well as the bond angles. The calculated values of the frequencies of vibrations of the various clusters have been compared with those obtained from the experimental Raman spectra of actual glasses, GexSe1?x(0 < x < 0.3). The local concentration, x within 0.25 nm is nonuniform in the amorphous material. When the same cluster occurs in two stable configurations, low frequency vibrations of frequency, ν < 100 cm?1, are found. The corner sharing GeSe4 has low frequency modes at 54 cm?1 and 93 cm?1 whereas these modes disappear in the pyramidal configuration. The low frequency modes are therefore associated with the breaking of C4 symmetry of the pyramidal configuration. The computed vibrational frequencies of clusters Ge3, Ge4Se3, Ge2Se3, GeSe3 and Ge3Se2 are actually present in the Raman spectra of the glass, GexSe1?x(0 < x < 0.3). 相似文献
993.
Hussein Bassal Akram Hijazi Hussein Farhan Christine Trabolsi Bouchra Sayed Ahmad Alia Khalil Marc Maresca Fawaz El Omar 《Molecules (Basel, Switzerland)》2021,26(15)
Psophocarpus tetragonolobus has long been used in traditional medicine and cuisine. In this study, Psophocarpus tetragonolobus extracts were isolated by maceration and ultrasound-assisted extraction and were evaluated for their antioxidant and anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The obtained results show that both extracts (maceration and ultrasound) were rich in bioactive molecules and exerted substantial antioxidant and anti-inflammatory effects. The P. tetragonolobus extracts’ treatment in LPS-stimulated RAW264.7 macrophages resulted in a significant downregulation of the expressions of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β mRNA. In addition, the P. tetragonolobus extracts’ treatment attenuated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression. Our observations indicate that there is no significant difference between the two studied extracts of P. tetragonolobus in terms of biological properties (specifically, antioxidant and anti-inflammatory effects. Regardless of the extraction method, P. tetragonolobus could be used for treating diseases related to oxidative stress and inflammatory reactions. 相似文献
994.
The electrochemical behavior of Zn in 0.5 M NaOH solutions containing various concentrations (0.01–0.1 M) of ClO3 ? or ClO4 ? anions was studied with potentiodynamic anodic polarization and chronoamperometry techniques. Microstructural and topographical characterization of the pitted surfaces was carried out by ex situ scanning electron microscopy and atomic force microscopy examinations. Addition of either ClO3 ? or ClO4 ? stimulated general corrosion and ruptured the passive layer (stable pitting), with ClO3 ? being more aggressive than ClO4 ?. Metastable pitting events appear as current oscillations (spikes) at potentials close to the pitting potential when Cl? ions are produced by cathodic reduction of ClO3 ? and ClO4 ? before passive layer growth. Current–time measurements are performed at fixed potential after production of Cl? ions and show that the rate of metastable pitting and the intensity of current spikes increase with the potential and the concentration of aggressive anions. Concepts of thin film growth are applied to the passive layer formation in order to explain those results. Metastable events are related to the presence of defects in the passive layer because their frequency and intensity are enhanced in conditions that favor defect formation and roughening in growing films, while stable pitting typically occurs at regions of high metal disorder. 相似文献
995.
Hexametaphosphate‐Capped Silica Mesoporous Nanoparticles Containing CuII Complexes for the Selective and Sensitive Optical Detection of Hydrogen Sulfide in Water 下载免费PDF全文
Sameh El Sayed Dr. Michele Milani Prof. Maurizio Licchelli Prof. Ramón Martínez‐Máñez Dr. Félix Sancenón 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7002-7006
CuII‐macrocycle functionalized hexametaphosphate‐capped silica mesoporous nanoparticles have been prepared and used for the selective and sensitive detection of hydrogen sulfide in aqueous environments. The possibility of using different metal complexes combined with different capping anions and choice of different dyes or other sensing molecules as indicators makes this new protocol highly appealing for the preparation of new sensing systems for sulfide detection in different environments. 相似文献
996.
997.
998.
Synthesis,Characterization, and Catalytic Activity of New Cu(II) Complexes of Schiff Base: Effective Catalysts for Decolorization of Acid Red 37 Dye Solution 下载免费PDF全文
In this paper, three new Cu(II) Schiff base complexes with three different anions (acetate, chloride, and nitrate) were successfully synthesized and characterized by elemental analysis, mass spectra, molar conductance, FT‐IR, NMR,UV–vis spectroscopy, magnetic moment, ESR, and thermal analysis. The catalytic performances of these complexes in decolorization of azo dye, Acid Red 37, were evaluated. Copper(II) complexes were found to be an efficient catalyst for decolorization of Acid Red 37 in the presence of hydrogen peroxide. The catalytic investigation revealed that the Cu(II) complex with acetate anion (complex 1 ) performed the highest catalytic activity. The kinetics of the decolorization of AR37 with this catalyst was studied, and the observed rate constant was determined. The effects of different reaction parameters such as catalyst dosage, solution pH, initial concentration of H2O2, dye solution, and reaction temperature on the reaction rate constant were studied. The best reacting conditions should be catalyst dosage = 0.004 g, initial pH 4.0, [H2O2]0 = 0.8 M, and [AR37]0 = 1.16 M at temperature 25°C. Under these conditions, about 99% of AR37 was decolorized within 60 min. The results indicated that the Cu(II) complex with the acetate anion is a promising catalyst for wastewater treatment. 相似文献
999.
Benzoxazinones are easily prepared using Passerini–Smiles couplings of o-nitrophenol derivatives. Palladium-catalyzed flow-hydrogenation of adducts gives aniline derivatives that cyclize into benzoxazinones on treatment with trifluoroacetic acid. 相似文献
1000.