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151.
152.
A.M. Abd El-Aty Jeong-Heui Choi Sathya Khay Ho-Chul Shin Byung-Joon Chang Jae-Han Shim 《Analytica chimica acta》2009,631(1):108-115
Since its extensive development in the early 1980s, SFE has attracted considerable attention as a sample-preparation procedure. However, other different sample preparation procedures, including precipitation, liquid- and/or solid-phase extraction in biological fluids, also remain in use. In this investigation, SFE was introduced to isolate and identify orbifloxacin from plasma and milk. Four parameters, including the temperature and the pressure of supercritical fluid, modifier ratios, and dynamic extraction time, were evaluated and optimized to obtain the best yield of the analyte from the biological fluids. Determinations of the orbifloxacin (OBFX) in the extracts were carried out using HPLC-FLD. The optimum conditions of the extraction process that yielded the maximum analyte extraction efficiencies were 150 °C vs. 60 °C, 250 kg cm−2, 30% vs. 35% methanol, and 40 min vs. 20 min, for plasma and milk, respectively. The linearity of the calibration curves as well as the instrument LODs/LOQs were evaluated. Good linearity (at least r2 ≥ 0.999) of the calibration curves was obtained over the range from 0.2 to 0.01 μg mL−1. The method showed a good recovery rate (74.2-127.73%) and precision (RSDs: 1.64-20%). The instrumental LOD and LOQ values were 0.004 μg mL−1 vs. 0.01 μg mL−1 or 0.006 μg mL−1 vs. 0.02 μg mL−1, for plasma and milk, respectively. The method was successfully applied to estimate the pharmacokinetic variables of orbifloxacin in lactating does. To the best of our knowledge, this is the first time that SFE has been applied to isolate an antimicrobial agent from biological fluids. This method is promising for clinical applications and for pharmacokinetic studies of various pharmaceuticals in biological fluids. 相似文献
153.
Luminescent group 4 complexes derived from o-carborane, M(η5:η1-CpCMe2CB10H10C)2 (M = Ti; 1, Zr; 2, Hf; 3) and Me2Si(η5-Ind)[η5:η1-Cp-3-(CMe2CB10H10C)]ZrCl (4) were explored. While the Ti complex 1 possessing C2 molecular symmetry shows non-centrosymmetry in the unit cell as identically observed in 2 and 3, the double-ansa Zr complex 4 crystallizes in centrosymmetric P21/n space group despite its C1 molecular symmetry. The non-centrosymmetric crystals of 2 and 3 exhibit blue mechanoluminescence similar to their solution and solid state photoluminescence. In contrast, 1 is lacking mechanoluminescence in crystal and shows much weaker emission than other congeners in solution. The electroluminescence devices based on 2 or 3 doped poly(N-vinylcarbazole) (PVK) as an emitting layer display green electroluminescence, which turned out to be originated from the exciplexes formed between the complex and PVK host. Although the double ansa-Zr complex 4 does not show mechanoluminescence owing to the centrosymmetric nature, it exhibits good electron-transporting properties when incorporated into the electron-transporting layer of Alq3-based OLEDs. 相似文献
154.
Yongsoon Shin In-Tae Bae Gregory J. Exarhos 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,348(1-3):191-195
A completely “green” synthetic approach has been developed for the reduction and stabilization of Pt nanoparticles followed by self-assembly into nanowires in an aqueous β-d-glucose solution. Hydrothermal treatment initiated the reduction of Pt(IV) ions dispersed in a pH 8.0 β-d-glucose solution. The Pt nanoparticles were stabilized with oxidized glucose molecules. The Pt nanoparticles continued growing into nanowires followed by transformation into cubic nanocrystals with a rough needle surface. Evidence from TEM and FT-IR spectra reveal that carboxylate groups, which are generated by the oxidation of β-d-glucose, strongly interact with and stabilize the surface of these Pt nanostructures. 相似文献
155.
Shanmugam Easwaramoorthi Dr. Jae‐Yoon Shin Sung Cho Dr. Pyosang Kim Yasuhide Inokuma Eiji Tsurumaki Atsuhiro Osuka Prof. Dr. Dongho Kim Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(44):12005-12017
Donor–acceptor systems based on subporphyrins with nitro and amino substituents at meta and para positions of the meso‐phenyl groups were synthesized and their photophysical properties have been systematically investigated. These molecules show two types of charge‐transfer interactions, that is, from center to periphery and periphery to center depending on the peripheral substitution, in which the subporphyrin moiety plays a dual role as both donor and acceptor. Based on the solvent‐polarity‐dependent photophysical properties, we have shown that the fluorescence emission of para isomers originates from the solvatochromic, dipolar, symmetry‐broken, and relaxed excited states, whereas the non‐solvatochromic fluorescence of meta isomers is of the octupolar type with false symmetry breaking. The restricted meso‐(4‐aminophenyl) rotation at low temperature prevents the intramolecular charge‐transfer (ICT)‐forming process. The two‐photon absorption (TPA) cross‐section values were determined by photoexcitation at 800 nm in nonpolar toluene and polar acetonitrile solvents to see the effect of ICT on the TPA processes. The large enhancement in the TPA cross‐section value of approximately 3200 GM (1 GM=10?50 cm4 s photon?1) with donor–acceptor substitution has been attributed to the octupolar effect and ICT interactions. A correlation was found between the electron‐donating/‐withdrawing abilities of the peripheral groups and the TPA cross‐section values, that is, p‐aminophenyl>m‐aminophenyl>nitrophenyl. The increased stability of octupolar ICT interactions in highly polar solvents enhances the TPA cross‐section value by a factor of approximately 2 and 4, respectively, for p‐amino‐ and m‐nitrophenyl‐substituted subporphyrins. On the other hand, the stabilization of the symmetry‐broken, dipolar ICT state gives rise to a negligible impact on the TPA processes. 相似文献
156.
Hsian‐Wen Wang Zhi‐Chang Liu Chih‐Hsien Chen Dr. Tsong‐Shin Lim Prof. Wunshain Fann Prof. Chih‐Gang Chao Jian‐Yuan Yu Shern‐Long Lee Chun‐hsien Chen Prof. Shou‐Ling Huang Tien‐Yau Luh Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(23):5719-5728
You can append on me! Porphyrin‐appended polynorbornenes derived from 5,6‐endo‐fused N‐arylpyrrolidenonorbornenes have been shown to have coherently aligned pendant groups that exhibit exciton coupling and fluorescence quenching in the absorption and emission profiles (see figure).
157.
Degradation of acridine orange (AO) in aqueous solution by Fenton's reagent (Fe2+ and H2O2) was investigated. The effects of different reaction parameters such as initial AO concentration, pH value of solution, ferrous concentration, hydrogen peroxide concentration, and the presence of chloride ion on the oxidative degradation of AO were investigated. Under optimum conditions, 2 mM H2O2, 0.4 mM Fe2+ and pH 3.0, the initial 0.2 mM AO solution was reduced by 95.8% within 10 min. The primary intermediates of the degradation reaction of AO were identified. The analytical results indicated that the N‐de‐methylation degradation of AO dye took place in a stepwise manner to yield mono‐, di‐, tri‐, and tetra‐N‐de‐methylated AO species generated during the Fenton process. The probable degradation pathways were proposed and discussed. 相似文献
158.
Taguchi Y Ohtani H Tsuge S Ishida Y Kimura K Yoshikawa T 《Journal of chromatography. A》2003,993(1-2):137-142
Highly sensitive and specific determination of trace amounts of a polymeric hindered amine light stabilizer (HALS) in polypropylene (PP) materials could be established by improving reactive thermal desorption-gas chromatography (RTD-GC) in the presence of an organic alkali, tetramethylammonium hydroxide. By using nitrogen-phosphorus detection, highly selective detection of the HALS-related components was attained. In addition, the use of a polar poly(ethylene glycol) separation column alleviated the adsorption of minor specific pyrolysis products. This modified RTD-GC method allowed the determination of the polymeric HALS (Mr 1900) in PP even for trace concentrations between 100 and 500 ppm, through observing selectively the characteristic products containing a tetramethylpiperidine moiety, which had been impossible to detect under the previous RTD-GC conditions using a non-polar separation column and conventional flame ionization detection. 相似文献
159.
Sadia Ameen M. Shaheer Akhtar Young Soon Kim O-Bong Yang Hyung-Shik Shin 《Colloid and polymer science》2010,288(16-17):1633-1638
The organic–inorganic poly(1-naphthylamine)/ZnO (PNA/ZnO) nanocomposites were synthesized by in situ chemical oxidative polymerization of 1-naphthylamine monomer and ZnO nanomaterials for the photocatalytic degradation of methylene blue (MB) dye under visible light. The surface properties of PNA molecules were altered by adding the ZnO nanomaterials. The crystalline and the optical properties of PNA/ZnO nanocomposites were improved with the increased contents of ZnO nanomaterials in PNA molecules due to the effective interaction of PNA to the surface of ZnO nanomaterials. The prepared PNA/ZnO nanocomposites presented moderate photocatalytic MB dye degradation of ~22% under visible light. The occurrence of dye degradation under visible light might attribute to high-charge separation of ē-h+ pairs at the interfaces of PNA and ZnO nanomaterials in its excited state under light irradiation. 相似文献
160.
Ju-Kyung Shin So Mi Jeong Yongsug Tak Sung-Hyeon Baeck 《Research on Chemical Intermediates》2010,36(6-7):715-724
MoO3/Pt binary catalysts with various Mo/Pt ratios were prepared by an electrodeposition method for use as the anode in a direct methanol fuel cell. Pt was electrodeposited onto indium tin oxide (ITO) substrate, and then MoO3 was electrodeposited from an Mo-peroxo electrolyte on the top of Pt with different deposition times. The crystallinity of synthesized films was analyzed by X-ray diffraction (XRD), and the oxidation state of both the platinum and molybdenum were determined by X-ray photoelectron spectroscopy (XPS) analyses. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM/EDS) was employed to investigate the surface morphology and composition. The catalytic activity and stability for methanol oxidation were measured using cyclic voltammetry and chronoamperometry in a mixture of 0.5 M H2SO4 and 0.5 M CH3OH aqueous solution. Electrocatalytic activity for CO oxidation was also evaluated in a 0.5-M H2SO4 solution. The addition of a proper amount of MoO3 was found to significantly improve both the catalytic activity and stability for methanol oxidation. 相似文献