Papers by Keyword: Fluorescence Spectroscopy

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Authors: M. Elisa, Ileana Cristina Vasiliu, Cristiana Eugenia Ana Grigorescu, B. Grigoras, H. Niciu, Daniela Niciu, Aurelia Meghea, Nicoleta Iftimie, Maria Giurginca, Patrascu Roxana, Joe Trodahl, M. Dalley
Abstract: A wet non-conventional method for preparing aluminophosphate glasses is presented. Aluminophosphate glasses belonging to the oxide system Li2O-BaO-Al2O3-La2O3-P2O5, doped with rare-earth ions (Pr3+, Er3+, Gd3+, and Yb3+) were obtained. The influence of the doping ions on the optical properties of the phosphate glasses has been investigated in relation with micro-structural and local electronic phenomena The optical behavior of Li2O-BaO-Al2O3-La2O3-P2O5 glasses doped with 3% mol. rare-earth ions has been studied by ultra-violet-visible-near-infra-red (UV-VISNIR) spectroscopy. The transmission spectra revealed electronic transitions between 4f and 6s inner orbital of the rare-earth ions. Structural information via optical phonons was provided by infra-red (IR) absorption spectra in the range 400-4000 cm-1. IR optical phonons are characteristic for the vitreous phosphate network, showing out the glass network-forming role of P2O5. The absorption spectra present the main PO2 and P-O-P symmetrical stretch modes besides P-O-P bend mode, P-OH, P=O, PO3 2-, asymmetrical and symmetrical vibration modes. Fluorescence spectra of the rareearth- doped aluminophosphate glasses, in the visible range, were obtained by laser excitation at 514.5 nm. The fluorescence signals revealed specific electronic transitions, which provide visible and near-infra-red emission. Glasses containing rare-earth ions exhibit luminescence at the following wavelengths: Pr3+ ions at 820 nm and 880 nm, Er3+ ions at 520 nm, 550 nm and 560 nm, Gd3+ ions at 530 nm, 540 nm, 550 nm 820 and 880 nm, Yb3+ions at 530 nm, 540 nm, 550 nm and 980 nm.
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Authors: Jia Yue Sun, Qiu Mei Di, Qi Guang Xu, Liu Han
Abstract: A novel method has been developed to detect 1,2-benzisothiazolin-3-one (BIT) in paper for food packaging by hydrothermal extraction coupled with fluorescence spectroscopy in paper for food package. Parameters affecting fluorescence intensity have been evaluated, including the pH of solvents and the effect of surfactants. It turned out to be that fluorescent spectroscopy was a sensitive and easy method to determine BIT in paper package. The regression equation obtained was liner, and the correction coefficient was 99.9%, the limit detection (LOD) was 25.3μg/L, method detection limit (MDL) was 0.25mg/kg, which turned out that this method was sensitive and precise to determine BIT in food package.
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Authors: Xiao Wang, Jiang Xu, Mu Hua Liu, Jin Hui Zhao, Qian Hong
Abstract: Gentamicin is a kind of aminoglycoside antibiotics and widely used in the prevention and treatment of the duck diseases. A prediction model was established for the rapid detection of Gentamicin residue in duck meat using fluorescence analysis method according to the strong fluorescent characteristic of the generated derivative for Gentamicin and o-phthaldialdehyde (OPA) in the presence of emulsifier OP-10 and mercaptoethanol.The fluorescence spectra of the duck meat containing Gentamicin were analyzed, the optimum excitation wavelength of the material was 340 nm and the optimum emission wavelength was 442 nm. Fluorescence intensity and the concentration of the standard samples presented the good linear relationship, the linear correlation coefficient was 0.9963 and the limit of detection was 0.47 μg/mL in the dynamic rang of 0.5 ~6.5μg/mL. The correlation coefficient of regression equation was 0.9968 for the samples of duck meat extract. The experimental results showed that the fluorescence analysis method had a good performance and accuracy in detecting the Gentamicin residue in duck meat.
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Authors: Feng Yu Deng, Ying Liu
Abstract: The effect of Fe3+ on the interaction between nitrofurazone (NF) and human serum albumin (HSA) was studied by fluorescence spectroscopy and UV-vis spectroscopy. The results from fluorescence spectra showed that Fe3+ increased the binding constant of NF to HSA, indicating longer storage time of NF in blood plasma. The effect model of Fe3+ was researched by binding distance and the UV-vis spectra, which showed that in the HSA-NF-Fe ternary system Fe-NF complex formed via metal ion bridge and enhanced the binding capability of NF to HSA.
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Authors: Ahmad Nazib Alias, T.I. Tunku Kudin, Z.M. Zabidi, M.K. Harun, Ab Malik Marwan Ali, Mohamad Faizul Yahya
Abstract: We present the results concerning the excitation and emissions spectra of Poly (N-carbazole) (PVK) blend with different compositions of polyvinylpyrrolidone (PVP). Doctor blade technique was used to coat the blended polymer on a quartz substrate. The influences of polymer composition to the excitation and emission spectra were observed under UV excitation source of a xenon lamp. The result shows a discrepancy in the maximum excitation, emission and Stokes shift for each samples. The variation of Full Width at Half Maximum (FWHM) for excitation and emission indicate that the variation in composition has affected on the fluorescence properties of the blended thin film polymer system. Fourier Transform Infrared (FTIR) spectroscopy reveals that the discrepancy in the emission and excitation properties of this polymer blending system is due to the discrepancy of infrared absorption peak in the carbazole functional group.
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Authors: Chu Zhou Deng, Song Liu, Chen Zhong Jia
Abstract: Fluorescence spectroscopy was performed to investigate the composition changes and characteristics of the leachate DOM (dissolved organic matter) during UV-TiO2 photocatalytic treatment process. The results showed that fulvic-like, tryptophan-like and humic acids-like matters were the main compounds in leachate. During photocatalytic treatment process, fluorescence spectroscopy of DOM changed considerably. The final products were mainly fulvic-like and tryptophan-like matters. In general, the fluorescence signals of humic acids-like matters had the most significant change, which disappeared entirely after 60 h treatment, implying that humic acids-like matters can be degraded preferentially by photocatalysis. The other notable change was in VIS fulvic-like matters region, which suggested that fulvic-like matters can be significantly degraded. In 72 h photocatalytic effluent, VIS fulvic-like, tryptophan-like and tyrosine-like matters were remained, and the last two matters were the dominant fractions. These results indicated that fulvic-like and humic acids-like matters with macromolecular can be degraded into protein-like matters with micro-molecular by photocatalysis.
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Authors: Ji Cheng Xu, Xin Shan Rong, Ting Tian, Feng Xian Qiu
Abstract: The inclusion complex formation between fluorescent sensor 3, 3’-benzidine/β-cyclodextrin derivative (BDCD) and pesticide carbaryl was studied and characterized by TEM, XRD and fluorescence spectroscopy. The stability constant and the stoichiometry of complex were determined. Based on the enhancement of the fluorescence intensity of carbaryl produced through complex formation, a new sensitive method for the determination of carbaryl was established. The linear relationship between the fluorescence intensity and carbaryl concentration was obtained in the range of 0.60-3.00 μmol/L with a correlation coefficient of 0.9946. The detection limit was 5.12 nmol/L. This method has been successfully applied to the determination of carbaryl pesticide residue in water, fruit and vegetable samples with satisfactory results, recoveries in the range of 94.12 % to 105.88 % were obtained. The method is rapid, simple, direct, economical, sensitive and useful for carbaryl analysis.
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Authors: Yan Qiu Liang, Ying Zhang
Abstract: Bovine serum albumin (BSA) and human serum albumin (HSA) interaction with 4-nitroaniline was investigated by fluorescence spectroscopy respectively. 4-Nitroaniline can strongly quench intrinsic fluorescence of BSA and HSA. 4-Nitroaniline exhibits a high affinity to bovine and human serum albumins. The binding constants K and the number binding site n were obtained by double-log regression equation. Negative enthalpy (ΔH) and positive entropy (ΔS) values indicated that both hydrogen bond and hydrophobic forces played a major role in the binding of 4-nitroaniline and SA. The results of synchronous fluorescence showed the polarity around tryptophan residues was decreased and the hydrophobicity was increased.
337
Authors: Ian P. Shapiro, Xiao Feng Zhao, Hui Xu, Ping Xiao
Abstract: The constrained sintering behavior of yttria stabilized zirconia coatings containing 1 wt. % alumina produced using electrophoretic deposition has been studied. Coatings have been characterized by scanning electron microscopy, micro-hardness and fluorescence spectroscopy after sintering in air at 1100°C and 1200°C. These coatings were compared with those that additionally contained 1 wt. % soda-lime glass. Micro-hardness and fluorescence spectroscopy are shown to accurately monitor the density of the coatings. Fluorescence spectroscopy showed that the density across the coating is even, as expected from modelling literature. The addition of 1 wt. % of soda-lime glass is shown to improve the sintered density of coatings.
177
Authors: Wei Liu, Xian Lan Chen, Ju Cheng Zhang, Yun Hui Long, Ling Shi, Na Wu
Abstract: With water as the medium, PVP as stabilizer and ammonia as complexing agents and adjusting pH value of the solution, we report an all-aqueous synthesis of highly photoluminescent and stable ZnS quantum dots (QDs) by water-phase synthesis reaction between ZnCl2 and NaS at different temperatures and times. The optimal reaction conditions of PVP-capped ZnS QDs were obtained through experiment as follows: the concentration ZnCl2 and NaS solution both are 1 mM, (PVP):(ZnCl2) = 0.0167 (v/v), (NH3):(ZnCl2)=1:300 (v/v), the optimal reaction temperature is 40 °C, the optimal reaction time is 30 min. With ammonia as complexing agents, Zn(OH)2 can dissolve in ammonia and form to complex ions ((Zn(NH3)4)2+), which make Zn2+ release slowly to control the nucleus growth rate of ZnS, thus obtain small size of nanoparticles. The fluorescence spectra shows that the emission peaks of ZnS QDs around ~395 nm and ~470 nm on the emission spectra, which are consistent with literatures, so nano-ZnS QDs was synthesized successfully in this paper.
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