The Experts below are selected from a list of 2871 Experts worldwide ranked by ideXlab platform
Qing Lin Liu - One of the best experts on this subject based on the ideXlab platform.
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enhanced performance of anion exchange membranes via crosslinking of ion cluster regions for fuel cells
Journal of Power Sources, 2016Co-Authors: Ao Nan Lai, Chen Xiao Lin, Qiu Gen Zhang, Ai Mei Zhu, Dong Guo, Qing Lin LiuAbstract:Abstract Development of anion exchange membranes (AEMs) with high hydroxide conductivity, good dimensional and alkaline stabilities is still a challenge for the practical application of AEM fuel cells. In this study, we report a new strategy to prepare high-performance AEMs with crosslinked ionic regions. A series of Phenolphthalein-containing poly(arylene ether sulfone)s crosslinked AEMs was synthesized by grafting ion groups selectively and densely on the Phenolphthalein units to form ion clusters that are further crosslinked to generate the hydrophilic ionic regions. The crosslinking reaction not only improved the dimensional stability of the AEMs, but also increased the aggregation of the ion clusters leading to the formation of hydrophilic/hydrophobic phase-separated morphology and ion-conducting channels. As a result, enhancements in both ion conductivity and dimensional stability can be achieved. The crosslinked AEMs showed high hydroxide conductivities in the range of 52.2–143.4 mS cm−1 from 30 to 80 °C and a superb ratio of relative conductivity to relative swelling at 80 °C. Furthermore, the crosslinked AEMs also exhibited good mechanical properties, thermal and alkaline stabilities and desirable single cell performance. This work presents a promising strategy for the synthesis of high-performance AEMs for fuel cells.
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Phenolphthalein based poly arylene ether sulfone nitrile s multiblock copolymers as anion exchange membranes for alkaline fuel cells
ACS Applied Materials & Interfaces, 2015Co-Authors: Ao Nan Lai, Li Sha Wang, Chen Xiao Lin, Yizhi Zhuo, Qiu Gen Zhang, Ai Mei Zhu, Qing Lin LiuAbstract:A series of Phenolphthalein-based poly(arylene ether sulfone nitrile)s (PESN) multiblock copolymers containing 1–methylimidazole groups (ImPESN) were synthesized to prepare anion exchange membranes (AEMs) for alkaline fuel cells. The ion groups were introduced selectively and densely on the unit of Phenolphthalein as the hydrophilic segments, allowing for the formation of ion clusters. Strong polar nitrile groups were introduced into the hydrophobic segments with the intention of improving the dimensional stability of the AEMs. A well-controlled multiblock structure was responsible for the well-defined hydrophobic/hydrophilic phase separation and interconnected ion–transport channels, as confirmed by atomic force microscopy and small angle X-ray scattering. The ImPESN membranes with low swelling showed a relatively high water uptake, high hydroxide ion conductivity together with good mechanical, thermal and alkaline stability. The ionic conductivity of the membranes was in the range of 3.85–14.67 × 10–2 S...
Adina Elena Raducanu - One of the best experts on this subject based on the ideXlab platform.
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spectroscopic and spectrometric methods used for the screening of certain herbal food supplements suspected of adulteration
Advanced Pharmaceutical Bulletin, 2017Co-Authors: Cristina Mateescu, Anca Mihaela Popescu, Gabriel Lucian Radu, Tatiana Onisei, Adina Elena RaducanuAbstract:Purpose: This study was carried out in order to find a reliable method for the fast detection of adulterated herbal food supplements with sexual enhancement claims. As some herbal products are advertised as "all natural", their "efficiency" is often increased by addition of active pharmaceutical ingredients such as PDE-5 inhibitors, which can be a real health threat for the consumer. Methodes: Adulterants, potentially present in 50 herbal food supplements with sexual improvement claims, were detected using 2 spectroscopic methods - Raman and Fourier Transform Infrared - known for reliability, reproductibility, and an easy sample preparation. GC-MS technique was used to confirm the potential adulterants spectra. Results: About 22% (11 out of 50 samples) of herbal food supplements with sexual enhancement claims analyzed by spectroscopic and spectrometric methods proved to be "enriched" with active pharmaceutical compounds such as: sildenafil and two of its analogues, tadalafil and Phenolphthalein. The occurence of Phenolphthalein could be the reason for the non-relevant results obtained by FTIR method in some samples. 91% of the adulterated herbal food supplements were originating from China. Conclusion: The results of this screening highlighted the necessity for an accurate analysis of all alleged herbal aphrodisiacs on the Romanian market. This is a first such a screening analysis carried out on herbal food supplements with sexual enhancement claims.
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Spectroscopic and Spectrometric Methods Used for the Screening of Certain Herbal Food Supplements Suspected of Adulteration
Tabriz University of Medical Sciences, 2017Co-Authors: Cristina Mateescu, Anca Mihaela Popescu, Gabriel Lucian Radu, Tatiana Onisei, Adina Elena RaducanuAbstract:Purpose: This study was carried out in order to find a reliable method for the fast detection of adulterated herbal food supplements with sexual enhancement claims. As some herbal products are advertised as "all natural", their "efficiency" is often increased by addition of active pharmaceutical ingredients such as PDE-5 inhibitors, which can be a real health threat for the consumer. Methodes: Adulterants, potentially present in 50 herbal food supplements with sexual improvement claims, were detected using 2 spectroscopic methods - Raman and Fourier Transform Infrared - known for reliability, reproductibility, and an easy sample preparation. GC-MS technique was used to confirm the potential adulterants spectra. Results: About 22% (11 out of 50 samples) of herbal food supplements with sexual enhancement claims analyzed by spectroscopic and spectrometric methods proved to be "enriched" with active pharmaceutical compounds such as: sildenafil and two of its analogues, tadalafil and Phenolphthalein. The occurence of Phenolphthalein could be the reason for the non-relevant results obtained by FTIR method in some samples. 91% of the adulterated herbal food supplements were originating from China. Conclusion: The results of this screening highlighted the necessity for an accurate analysis of all alleged herbal aphrodisiacs on the Romanian market. This is a first such a screening analysis carried out on herbal food supplements with sexual enhancement claims
Helmut Ritter - One of the best experts on this subject based on the ideXlab platform.
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color indicator for supramolecular polymer chemistry Phenolphthalein containing thermo and ph sensitive n isopropyl acrylamide copolymers and β cyclodextrin complexation
Macromolecular Rapid Communications, 2013Co-Authors: Carolin Fleischmann, Helmut RitterAbstract:The copolymerization parameters of N-(isopropyl)acrylamide (1) and N-(2-hydroxy-5-(1-(4-hydroxyphenyl)-3-oxo-1,3-dihydroisobenzofuran-1-yl)benzyl)acrylamide (2) are determined. For both monomers, the homoaddition proceeds slightly faster than the heteroaddition step; however, the polymer formation occurs in a statistic fashion. Copolymers of different compositions are prepared and the cloud points are determined. Thereby, a significant influence of the concentration of monomer 2 and the pH value is found. For the first time, the complexation of polymer attached Phenolphthalein by β-cyclodextrins is shown. Furthermore, it is possible to achieve a decomplexation by the addition of suitable guest molecules. Both procedures can be followed with the naked eye.
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poly n vinylpyrrolidone bearing covalently attached cyclodextrin via click chemistry synthesis characterization and complexation behavior with Phenolphthalein
Macromolecules, 2010Co-Authors: Taina Trellenkamp, Helmut RitterAbstract:We report about modification of poly(N-vinylpyrrolidone) (PVP) with monofunctional β-cyclodextrin (βCD) via click-chemistry. The modification was carried out by copper(I)-catalyzed microwave-assisted Huisgen-type cycloaddition of 3-propargyl-N-vinylpyrrolidone (2a) and mono(6-azido-6-deoxy)-β-cyclodextrin (3). We synthesized a copolymer (5) carrying CD moieties which has the same composition as the applied molar ratio of monomers. Complexation experiments of the obtained polymer (5) with Phenolphthalein (PP) showed a lower binding constant compared to βCD caused by sterical effects of the polymer coil.
Ao Nan Lai - One of the best experts on this subject based on the ideXlab platform.
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enhanced performance of anion exchange membranes via crosslinking of ion cluster regions for fuel cells
Journal of Power Sources, 2016Co-Authors: Ao Nan Lai, Chen Xiao Lin, Qiu Gen Zhang, Ai Mei Zhu, Dong Guo, Qing Lin LiuAbstract:Abstract Development of anion exchange membranes (AEMs) with high hydroxide conductivity, good dimensional and alkaline stabilities is still a challenge for the practical application of AEM fuel cells. In this study, we report a new strategy to prepare high-performance AEMs with crosslinked ionic regions. A series of Phenolphthalein-containing poly(arylene ether sulfone)s crosslinked AEMs was synthesized by grafting ion groups selectively and densely on the Phenolphthalein units to form ion clusters that are further crosslinked to generate the hydrophilic ionic regions. The crosslinking reaction not only improved the dimensional stability of the AEMs, but also increased the aggregation of the ion clusters leading to the formation of hydrophilic/hydrophobic phase-separated morphology and ion-conducting channels. As a result, enhancements in both ion conductivity and dimensional stability can be achieved. The crosslinked AEMs showed high hydroxide conductivities in the range of 52.2–143.4 mS cm−1 from 30 to 80 °C and a superb ratio of relative conductivity to relative swelling at 80 °C. Furthermore, the crosslinked AEMs also exhibited good mechanical properties, thermal and alkaline stabilities and desirable single cell performance. This work presents a promising strategy for the synthesis of high-performance AEMs for fuel cells.
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Phenolphthalein based poly arylene ether sulfone nitrile s multiblock copolymers as anion exchange membranes for alkaline fuel cells
ACS Applied Materials & Interfaces, 2015Co-Authors: Ao Nan Lai, Li Sha Wang, Chen Xiao Lin, Yizhi Zhuo, Qiu Gen Zhang, Ai Mei Zhu, Qing Lin LiuAbstract:A series of Phenolphthalein-based poly(arylene ether sulfone nitrile)s (PESN) multiblock copolymers containing 1–methylimidazole groups (ImPESN) were synthesized to prepare anion exchange membranes (AEMs) for alkaline fuel cells. The ion groups were introduced selectively and densely on the unit of Phenolphthalein as the hydrophilic segments, allowing for the formation of ion clusters. Strong polar nitrile groups were introduced into the hydrophobic segments with the intention of improving the dimensional stability of the AEMs. A well-controlled multiblock structure was responsible for the well-defined hydrophobic/hydrophilic phase separation and interconnected ion–transport channels, as confirmed by atomic force microscopy and small angle X-ray scattering. The ImPESN membranes with low swelling showed a relatively high water uptake, high hydroxide ion conductivity together with good mechanical, thermal and alkaline stability. The ionic conductivity of the membranes was in the range of 3.85–14.67 × 10–2 S...
Cristina Mateescu - One of the best experts on this subject based on the ideXlab platform.
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spectroscopic and spectrometric methods used for the screening of certain herbal food supplements suspected of adulteration
Advanced Pharmaceutical Bulletin, 2017Co-Authors: Cristina Mateescu, Anca Mihaela Popescu, Gabriel Lucian Radu, Tatiana Onisei, Adina Elena RaducanuAbstract:Purpose: This study was carried out in order to find a reliable method for the fast detection of adulterated herbal food supplements with sexual enhancement claims. As some herbal products are advertised as "all natural", their "efficiency" is often increased by addition of active pharmaceutical ingredients such as PDE-5 inhibitors, which can be a real health threat for the consumer. Methodes: Adulterants, potentially present in 50 herbal food supplements with sexual improvement claims, were detected using 2 spectroscopic methods - Raman and Fourier Transform Infrared - known for reliability, reproductibility, and an easy sample preparation. GC-MS technique was used to confirm the potential adulterants spectra. Results: About 22% (11 out of 50 samples) of herbal food supplements with sexual enhancement claims analyzed by spectroscopic and spectrometric methods proved to be "enriched" with active pharmaceutical compounds such as: sildenafil and two of its analogues, tadalafil and Phenolphthalein. The occurence of Phenolphthalein could be the reason for the non-relevant results obtained by FTIR method in some samples. 91% of the adulterated herbal food supplements were originating from China. Conclusion: The results of this screening highlighted the necessity for an accurate analysis of all alleged herbal aphrodisiacs on the Romanian market. This is a first such a screening analysis carried out on herbal food supplements with sexual enhancement claims.
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Spectroscopic and Spectrometric Methods Used for the Screening of Certain Herbal Food Supplements Suspected of Adulteration
Tabriz University of Medical Sciences, 2017Co-Authors: Cristina Mateescu, Anca Mihaela Popescu, Gabriel Lucian Radu, Tatiana Onisei, Adina Elena RaducanuAbstract:Purpose: This study was carried out in order to find a reliable method for the fast detection of adulterated herbal food supplements with sexual enhancement claims. As some herbal products are advertised as "all natural", their "efficiency" is often increased by addition of active pharmaceutical ingredients such as PDE-5 inhibitors, which can be a real health threat for the consumer. Methodes: Adulterants, potentially present in 50 herbal food supplements with sexual improvement claims, were detected using 2 spectroscopic methods - Raman and Fourier Transform Infrared - known for reliability, reproductibility, and an easy sample preparation. GC-MS technique was used to confirm the potential adulterants spectra. Results: About 22% (11 out of 50 samples) of herbal food supplements with sexual enhancement claims analyzed by spectroscopic and spectrometric methods proved to be "enriched" with active pharmaceutical compounds such as: sildenafil and two of its analogues, tadalafil and Phenolphthalein. The occurence of Phenolphthalein could be the reason for the non-relevant results obtained by FTIR method in some samples. 91% of the adulterated herbal food supplements were originating from China. Conclusion: The results of this screening highlighted the necessity for an accurate analysis of all alleged herbal aphrodisiacs on the Romanian market. This is a first such a screening analysis carried out on herbal food supplements with sexual enhancement claims