The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Shaopu Liu - One of the best experts on this subject based on the ideXlab platform.
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Fluorescence Quenching Reaction of Polyvinylpyrrolidone-Eosin Y System for the Determination of Polyvinylpyrrolidone
Journal of fluorescence, 2010Co-Authors: Zhongfang Liu, Ling Kong, Shaopu LiuAbstract:In pH 1.8-2.8 weak acid medium, Polyvinylpyrrolidone (PVP) and Eosin Y reacted to form complex that could result in Eosin Y (EY) fluorescence quenching. The maximum quenching wavelength was at 542 nm. The fluorescence quenching (DeltaF) was proportional to the concentration of Polyvinylpyrrolidone in a certain range. The linear range, the correlation coefficient and the detection limit were 0.33-2.0 microg x mL(-1), 0.9994 and 99.6 ng x mL(-1), respectively. The influences of the coexistence substances were tested and the results showed that the method had good selectivity. Therefore, a new method based on fluorescence quenching of eosin Y by PVP for the determination of trace PVP was developed. The method was sensitive, simple and rapid, which was applied to the determination of trace PVP in the beer with satisfactory results. The reaction mechanism was also discussed.
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Fluorescence Quenching Reaction of Polyvinylpyrrolidone-Eosin Y System for the Determination of Polyvinylpyrrolidone
Journal of fluorescence, 2010Co-Authors: Zhongfang Liu, Ling Kong, Shaopu LiuAbstract:In pH 1.8 ∼ 2.8 weak acid medium, Polyvinylpyrrolidone (PVP) and Eosin Y reacted to form complex that could result in Eosin Y (EY) fluorescence quenching. The maximum quenching wavelength was at 542 nm. The fluorescence quenching (ΔF) was proportional to the concentration of Polyvinylpyrrolidone in a certain range. The linear range, the correlation coefficient and the detection limit were 0.33 ∼ 2.0 μg•mL−1, 0.9994 and 99.6 ng•mL−1, respectively. The influences of the coexistence substances were tested and the results showed that the method had good selectivity. Therefore, a new method based on fluorescence quenching of eosin Y by PVP for the determination of trace PVP was developed. The method was sensitive, simple and rapid, which was applied to the determination of trace PVP in the beer with satisfactory results. The reaction mechanism was also discussed.
Vivian Bruce Sunderland - One of the best experts on this subject based on the ideXlab platform.
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Solid dispersions of dihydroartemisinin in Polyvinylpyrrolidone
Archives of Pharmacal Research, 2008Co-Authors: Muhammad Tayyab Ansari, Vivian Bruce SunderlandAbstract:In the present study the physicochemical characteristics of dihydroartemisinin, Polyvinylpyrrolidone and their solid dispersions were evaluated at various proportions of drug and Polyvinylpyrrolidone. These properties were investigated with X-ray diffraction, fourier transform infrared spectrophotometry, differential scanning calorimetry, equilibrium solubility at twenty five and thirty seven degree centigrade. X-ray diffraction analysis detected that dihydroartemisinin became more amorphous as drug carrier ratio was enhanced in solid dispersions. Fourier transform infrared spectra suggested that there was a hydrogen bonding interaction between dihydroartemisinin and Polyvinylpyrrolidone in all solid dispersions. These interactions reflected the changes in crystalline structures of dihydroartemisinin. The thermal behavior of dihydroartemisinin was unusual as it exhibited melting exotherm instead of endotherm. In solid dispersions containing varying contents of Polyvinylpyrrolidone, enthalpy change and peak area were enhanced while melting onset temperature decreased with increase in Polyvinylpyrrolidone proportion. This was attributed to a solid-state interaction. Equilibrium solubility of dihydroartemisinin increased sixty-fold due to induction of Polyvinylpyrrolidone. When this solubility was compared among thirty-seven and twenty five degree centigrade in solid dispersions, it was up to seven times more at higher temperature. Physicochemical characteristics of solid dispersions containing drug carrier ratio of one: nine prepared in acetonitrile, ethanol, methanol and tetrahydrofuran showed differences which indicated that properties of medium i.e. dielectric constant, dipole moment and structure, influenced the amount of amorphousness and related properties of dihydroartemisinin.
Zhongfang Liu - One of the best experts on this subject based on the ideXlab platform.
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Fluorescence Quenching Reaction of Polyvinylpyrrolidone-Eosin Y System for the Determination of Polyvinylpyrrolidone
Journal of fluorescence, 2010Co-Authors: Zhongfang Liu, Ling Kong, Shaopu LiuAbstract:In pH 1.8-2.8 weak acid medium, Polyvinylpyrrolidone (PVP) and Eosin Y reacted to form complex that could result in Eosin Y (EY) fluorescence quenching. The maximum quenching wavelength was at 542 nm. The fluorescence quenching (DeltaF) was proportional to the concentration of Polyvinylpyrrolidone in a certain range. The linear range, the correlation coefficient and the detection limit were 0.33-2.0 microg x mL(-1), 0.9994 and 99.6 ng x mL(-1), respectively. The influences of the coexistence substances were tested and the results showed that the method had good selectivity. Therefore, a new method based on fluorescence quenching of eosin Y by PVP for the determination of trace PVP was developed. The method was sensitive, simple and rapid, which was applied to the determination of trace PVP in the beer with satisfactory results. The reaction mechanism was also discussed.
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Fluorescence Quenching Reaction of Polyvinylpyrrolidone-Eosin Y System for the Determination of Polyvinylpyrrolidone
Journal of fluorescence, 2010Co-Authors: Zhongfang Liu, Ling Kong, Shaopu LiuAbstract:In pH 1.8 ∼ 2.8 weak acid medium, Polyvinylpyrrolidone (PVP) and Eosin Y reacted to form complex that could result in Eosin Y (EY) fluorescence quenching. The maximum quenching wavelength was at 542 nm. The fluorescence quenching (ΔF) was proportional to the concentration of Polyvinylpyrrolidone in a certain range. The linear range, the correlation coefficient and the detection limit were 0.33 ∼ 2.0 μg•mL−1, 0.9994 and 99.6 ng•mL−1, respectively. The influences of the coexistence substances were tested and the results showed that the method had good selectivity. Therefore, a new method based on fluorescence quenching of eosin Y by PVP for the determination of trace PVP was developed. The method was sensitive, simple and rapid, which was applied to the determination of trace PVP in the beer with satisfactory results. The reaction mechanism was also discussed.
Muhammad Tayyab Ansari - One of the best experts on this subject based on the ideXlab platform.
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Solid dispersions of dihydroartemisinin in Polyvinylpyrrolidone
Archives of Pharmacal Research, 2008Co-Authors: Muhammad Tayyab Ansari, Vivian Bruce SunderlandAbstract:In the present study the physicochemical characteristics of dihydroartemisinin, Polyvinylpyrrolidone and their solid dispersions were evaluated at various proportions of drug and Polyvinylpyrrolidone. These properties were investigated with X-ray diffraction, fourier transform infrared spectrophotometry, differential scanning calorimetry, equilibrium solubility at twenty five and thirty seven degree centigrade. X-ray diffraction analysis detected that dihydroartemisinin became more amorphous as drug carrier ratio was enhanced in solid dispersions. Fourier transform infrared spectra suggested that there was a hydrogen bonding interaction between dihydroartemisinin and Polyvinylpyrrolidone in all solid dispersions. These interactions reflected the changes in crystalline structures of dihydroartemisinin. The thermal behavior of dihydroartemisinin was unusual as it exhibited melting exotherm instead of endotherm. In solid dispersions containing varying contents of Polyvinylpyrrolidone, enthalpy change and peak area were enhanced while melting onset temperature decreased with increase in Polyvinylpyrrolidone proportion. This was attributed to a solid-state interaction. Equilibrium solubility of dihydroartemisinin increased sixty-fold due to induction of Polyvinylpyrrolidone. When this solubility was compared among thirty-seven and twenty five degree centigrade in solid dispersions, it was up to seven times more at higher temperature. Physicochemical characteristics of solid dispersions containing drug carrier ratio of one: nine prepared in acetonitrile, ethanol, methanol and tetrahydrofuran showed differences which indicated that properties of medium i.e. dielectric constant, dipole moment and structure, influenced the amount of amorphousness and related properties of dihydroartemisinin.
Panayota N. Zarmakoupis-zavos - One of the best experts on this subject based on the ideXlab platform.
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Assessment of a tablet drug delivery system incorporating nonoxynol-9 coprecipitated with Polyvinylpyrrolidone in preventing the onset of pregnancy in rabbits
Fertility and sterility, 1998Co-Authors: Panayiotis M Zavos, Juan R. Correa, Panayota N. Zarmakoupis-zavosAbstract:Abstract Objective: To assess the in vivo efficacy of the tablet drug delivery system containing nonoxynol-9 coprecipitated with Polyvinylpyrrolidone by delivering the spermicidal agents vaginally and evaluating their ability to prevent the onset of pregnancy in rabbits. Design: Controlled clinical study. Setting: Division of Laboratory and Animal Resources, College of Pharmacy, University of Kentucky. Animal(s): Forty-two New Zealand White female rabbits. Intervention(s): The rabbits were artificially inseminated at various intervals after vaginal insertion of the tablet drug delivery system containing either Polyvinylpyrrolidone only (0 minutes) or nonoxynol-9 coprecipitated with Polyvinylpyrrolidone (Polyvinylpyrrolidone/nonoxynol-9; 0, 3, 30, 180, and 360 minutes). The rabbits were induced to ovulate 6 hours before insemination by IM injection of hCG (200 IU). Main Outcome Measure(s): The onset of pregnancy in the rabbits was evaluated after insertion of the tablet drug delivery system containing Polyvinylpyrrolidone only or Polyvinylpyrrolidone/nonoxynol-9 at various intervals, followed by artificial insemination. Result(s): The onset of pregnancy was not reduced significantly when the tablet drug delivery system containing Polyvinylpyrrolidone or Polyvinylpyrrolidone/nonoxynol-9 was used and insemination was performed immediately after tablet insertion (time 0). However, pregnancy rates (PRs) were reduced significantly in the rabbits that received the tablet drug delivery system containing Polyvinylpyrrolidone/nonoxynol-9 and were inseminated at 3, 30, 180, and 360 minutes after tablet insertion. The highest PR reduction occurred between 30 and 180 minutes after insertion of the tablet drug delivery system containing Polyvinylpyrrolidone/nonoxynol-9. Conclusion(s): The tablet drug delivery system is an efficient method of delivering the tested spermicidal agents vaginally. The design and dosage used in preparing the tablet drug delivery system provide short- and long-term release of the spermicidal agents, which results in almost immediate and extended enhancement of their contraceptive properties.
