The Experts below are selected from a list of 13278 Experts worldwide ranked by ideXlab platform
Changqing Wu - One of the best experts on this subject based on the ideXlab platform.
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application of pulsed light pl surfactant combination on inactivation of salmonella and apparent quality of green Onions
Lwt - Food Science and Technology, 2015Co-Authors: Wenqing Xu, Haiqiang Chen, Changqing WuAbstract:Abstract In our previous study using pulsed light (PL) and PL-sanitizer/surfactant to inactivate Escherichia coli O157:H7 on green Onions, the combination of PL and 1000 ppm of surfactant (sodium dodecyl sulfate, SDS) was more effective than single treatments. In this study, whether PL-surfactant combination would provide similar inactivation efficacy of Salmonella on green Onions was tested. Different surfactants (SDS and Tween 80) as well as different concentrations (10, 100 and 1000 ppm) of each surfactant combined with PL were tested. Survival populations of Salmonella and quality of green Onions (color and texture) were evaluated after treatments as well as during storage (15 days) at 4 °C. The results showed that PL-SDS and PL-Tween 80 combinations at various surfactant concentrations provided synergistic inactivation efficacy on green onion leaves (2.6–2.9 log10 CFU/g and 2.4–2.7 log10 CFU/g, respectively), but not on their stems (0.4–1.0 log10 CFU/g and 0.3–0.6 log10 CFU/g, respectively). PL-1000 ppm SDS combination negatively impacted color and texture of green Onions during 15 day storage at 4 °C. To consider both safety and quality of green Onions, PL-10 ppm SDS was selected since it showed similar Salmonella inactivation on green Onions as PL-1000 ppm SDS but did not affect quality of green Onions during shelf-life.
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decontamination of salmonella enterica typhimurium on green Onions using a new formula of sanitizer washing and pulsed uv light pl
Food Research International, 2014Co-Authors: Wenqing Xu, Changqing WuAbstract:Abstract Pathogenic bacteria such as Salmonella and Shigella flexneri have been linked to green onion contamination. This study was conducted to evaluate decontamination of Salmonella Typhimurium using a new formula of sanitizer washing (0.4 mg/mL thymol and five new formula sanitizers including 300 ppm H 2 O 2 + 4% SDS, 2 mg/mL citric acid + 4% SDS, 0.2 mg/mL thymol + 4% SDS, 0.2 mg/mL thymol + 2 mg/mL citric acid and 0.2 mg/mL thymol + 2 mg/mL acetic acid), pulsed UV light (PL) as well as synergy between the sanitizer wash and PL. New formula sanitizers based on decontamination efficacy of single washing solutions (organic acids, hydrogen peroxide (H 2 O 2 ), essential oil or surfactant) were applied to decontaminate spot inoculated green Onions. PL, the novel technique, alone has been applied to inactivate Salmonella on both dip and spot inoculated green Onions. Salmonella inactivation of PL–new formula sanitizer combinations on dip inoculated green Onions was investigated for their potential synergy. As a result, for spot inoculated green Onions, 0.4 mg/mL thymol individually and the five new formula sanitizers all achieved higher log reduction of Salmonella (4.5–5.3 log 10 CFU/g reduction) than the 200 ppm chlorine washing. These new formulas of sanitizer would be potential alternatives to chlorine. The 5 s dry PL (4.6 log 10 CFU/g) or 60 s wet PL treatment (3.6 log 10 CFU/g) was better or comparable as chlorine washing. The sanitizer combinations did not provide significantly higher log reduction than PL, and PL has the potential of being used in the green onion industry for decontamination purpose. For dip inoculated green Onions, none of our treatment provided > 0.8 log 10 CFU/g (0.6–0.8 log 10 CFU/g) reduction of Salmonella . As a result, the PL–new formula sanitizer combinations had no or minimal synergy to inactivate Salmonella dip inoculated on green Onions.
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decontamination of escherichia coli o157 h7 on green Onions using pulsed light pl and pl surfactant sanitizer combinations
International Journal of Food Microbiology, 2013Co-Authors: Wenqing Xu, Haiqiang Chen, Yaoxin Huang, Changqing WuAbstract:Abstract Imported green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported green Onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on green Onions. Green Onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated green Onions were found to be more difficult to be decontaminated. Results showed that 5 s dry PL (samples were not immersed in water during PL treatment) and 60 s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (> 4 log 10 CFU/g) for spot inoculated stems and leaves. For dip inoculated green Onions, 60 s wet PL treatment was comparable with 100 ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL–SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000 ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of green Onions by 1.4 and 3.1 log 10 CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on green Onions, with wet PL added with SDS being the most effective PL treatment.
Yury Gogotsi - One of the best experts on this subject based on the ideXlab platform.
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pseudocapacitance and performance stability of quinone coated carbon Onions
Nano Energy, 2013Co-Authors: Daniela M Anjos, Joh K Mcdonough, Emilie Perre, S H Overbury, Yury Gogotsi, Volke PresseAbstract:Onion-like carbon, also known as carbon Onions, is a highly conductive material enabling supercapacitor electrodes with a very high power density. However, the moderate specific capacitance (circa 30 F/g) is insufficient for many energy storage applications. In our study, we show how decoration of carbon Onions with quinones provides a facile method to increase the energy density up to one order of magnitude, namely, from 0.5 Wh/kg to 4.5 Wh/kg, while retaining a high power density and long lifetime. We present data for carbon Onions modified with three different kinds of quinones: 1,4-naphthoquinone, 9,10-phenanthrenequinone, and 4,5-pyrenedione. Quinone-decorated carbon onion electrodes are investigated considering the actual quinone loading and the resulting electrochemical performance is probed in 1 M H2SO4 as the electrolyte using cyclic voltammetry and galvanostatic charge/discharge. The maximum capacitance, 264 F/g, is found for carbon Onions modified with 4,5-pyrenedione, which also shows the smallest fade in specific capacitance, namely 3%, over 10,000 charge and discharge cycles at a high current density of 1.3 A/g.
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carbon Onions synthesis and electrochemical applications
The Electrochemical Society interface, 2013Co-Authors: Joh K Mcdonough, Yury GogotsiAbstract:Onion-like carbon (OLC) structures have been synthesized in many ways and large scale production is under study nowadays. The annealing method can satisfy the need for large scale production, though the ideal spherical shape is unachievable, and the temperature attainable in this method is not sufficient for treating the entire particle. The arc-discharge method provides an alternate pathway toward large scale synthesis. Due to its structure and electrochemical properties, carbon Onions can be used as materials for electrochemical double layer capacitors (EDLC) and can be used to store energy across a much wider temperature range, which gives these materials advantages over conventional EDLCs. This and other aspects of carbon Onions are discussed in this article.
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influence of the structure of carbon Onions on their electrochemical performance in supercapacitor electrodes
Carbon, 2012Co-Authors: Joh K Mcdonough, Volke Presse, Andrey I Frolov, Junjie Niu, Christophe H Mille, Teresa Ubieto, Maxim V Fedorov, Yury GogotsiAbstract:Onion-like carbon (OLC), also known as carbon Onions, is an attractive material for electrical energy storage in regards to high rate, high power applications. We report the most up to date, systematic, and extensive study of the electrochemical behavior of carbon Onions in aqueous (1 M sulfuric acid, H2SO4) and organic (1 M tetraethylammonium tetrafluoroborate, TEA-BF4, and 1 M tetrabutylammonium tetrafluoroborate, TBA-BF4, in acetonitrile) electrolytes. The physical and electrical properties of OLC are studied as a function of the synthesis temperature and compared with diamond soot, carbon black, and activated carbon. To obtain a molecular scale picture of the processes at the OLC-electrolyte interface, we supplement the experimental work with molecular dynamics (MD) simulations of carbon Onions in organic electrolytes. The capacitive performance of OLC exceeds other carbon materials at high charge/discharge rates (up to 50 V s(-1); time constant tau similar to 10 ms). OLC produced from detonation soot has a performance similar to that of OLC from highly purified nanodiamond. While OLC produced at 1500 degrees C has the largest specific surface area, OLC produced at 1800 degrees C has the highest conductivity and shows the best capacitive performance at high rates.
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electrochemical performance of carbon Onions nanodiamonds carbon black and multiwalled nanotubes in electrical double layer capacitors
Carbon, 2007Co-Authors: Cristelle Portet, Gleb Yushin, Yury GogotsiAbstract:Abstract This paper describes the electrochemical performance of carbon Onions, nanodiamonds, carbon black and multiwalled nanotubes as electrodes in electrical double layer capacitors with organic electrolyte. Onions were formed by vacuum annealing of 5 nm nanodiamond (ND) powder at 1200–2000 °C with the goal to investigate the effect of carbon microstructure on specific capacitance and ion transport. In contrast to micro- or mesoporous activated carbons, the outer surface of carbon Onions is fully accessible to electrolyte ions and the size of pores between carbon Onions or nanotubes does not depend on the annealing temperature. Charge-discharge measurements revealed a two times decrease in the specific capacitance of Onions and nanotubes upon graphitization and formation of polyhedral particles after annealing at 1800 °C and above. However, the capacitance became less current dependant. The carbon onion cells are able to deliver the stored energy under a high current density with a capacitance twice than the one obtained with MWCNT. Electrical measurements and impedance spectroscopy showed about two orders of magnitude increase in conductivity of electrodes and twofold decrease in the equivalent series resistance of the assembled cells after heat treatments of ND. The time constant extracted from the impedance data is around 10 times smaller for ND annealed at above 1800 °C than for activated carbons and is closely approaching the one for MWCNT. This shows that the open structure of carbon Onions leads to an increased ability to quickly deliver the stored energy.
Volke Presse - One of the best experts on this subject based on the ideXlab platform.
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review carbon Onions for electrochemical energy storage
Journal of Materials Chemistry, 2016Co-Authors: Volke Presse, Marco Zeige, Nicolas Jackel, Vadym MochaliAbstract:Carbon Onions are a relatively new member of the carbon nanomaterials family. They consist of multiple concentric fullerene-like carbon shells which are highly defective and disordered. Due to their small size of typically below 10 nm, the large external surface area, and high conductivity they are used for supercapacitor applications. As electrode materials, carbon Onions provide fast charge/discharge rates resulting in high specific power but present comparatively low specific energy. They improve the performance of activated carbon electrodes as conductive additives and show suitable properties as substrates for redox-active materials. This review provides a critical discussion of the electrochemical properties of different types of carbon Onions as electrode materials. It also compares the general advantages and disadvantages of different carbon onion synthesis methods. The physical and chemical properties of carbon Onions, in particular nanodiamond-derived carbon Onions, are described with emphasis on those parameters especially important for electrochemical energy storage systems, including the structure, conductivity, and porosity. Although the primary focus of current research is on electrode materials for supercapacitors, the use of carbon Onions as conductive additives and for redox-active species is also discussed.
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pseudocapacitance and performance stability of quinone coated carbon Onions
Nano Energy, 2013Co-Authors: Daniela M Anjos, Joh K Mcdonough, Emilie Perre, S H Overbury, Yury Gogotsi, Volke PresseAbstract:Onion-like carbon, also known as carbon Onions, is a highly conductive material enabling supercapacitor electrodes with a very high power density. However, the moderate specific capacitance (circa 30 F/g) is insufficient for many energy storage applications. In our study, we show how decoration of carbon Onions with quinones provides a facile method to increase the energy density up to one order of magnitude, namely, from 0.5 Wh/kg to 4.5 Wh/kg, while retaining a high power density and long lifetime. We present data for carbon Onions modified with three different kinds of quinones: 1,4-naphthoquinone, 9,10-phenanthrenequinone, and 4,5-pyrenedione. Quinone-decorated carbon onion electrodes are investigated considering the actual quinone loading and the resulting electrochemical performance is probed in 1 M H2SO4 as the electrolyte using cyclic voltammetry and galvanostatic charge/discharge. The maximum capacitance, 264 F/g, is found for carbon Onions modified with 4,5-pyrenedione, which also shows the smallest fade in specific capacitance, namely 3%, over 10,000 charge and discharge cycles at a high current density of 1.3 A/g.
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influence of the structure of carbon Onions on their electrochemical performance in supercapacitor electrodes
Carbon, 2012Co-Authors: Joh K Mcdonough, Volke Presse, Andrey I Frolov, Junjie Niu, Christophe H Mille, Teresa Ubieto, Maxim V Fedorov, Yury GogotsiAbstract:Onion-like carbon (OLC), also known as carbon Onions, is an attractive material for electrical energy storage in regards to high rate, high power applications. We report the most up to date, systematic, and extensive study of the electrochemical behavior of carbon Onions in aqueous (1 M sulfuric acid, H2SO4) and organic (1 M tetraethylammonium tetrafluoroborate, TEA-BF4, and 1 M tetrabutylammonium tetrafluoroborate, TBA-BF4, in acetonitrile) electrolytes. The physical and electrical properties of OLC are studied as a function of the synthesis temperature and compared with diamond soot, carbon black, and activated carbon. To obtain a molecular scale picture of the processes at the OLC-electrolyte interface, we supplement the experimental work with molecular dynamics (MD) simulations of carbon Onions in organic electrolytes. The capacitive performance of OLC exceeds other carbon materials at high charge/discharge rates (up to 50 V s(-1); time constant tau similar to 10 ms). OLC produced from detonation soot has a performance similar to that of OLC from highly purified nanodiamond. While OLC produced at 1500 degrees C has the largest specific surface area, OLC produced at 1800 degrees C has the highest conductivity and shows the best capacitive performance at high rates.
Peter Fodor - One of the best experts on this subject based on the ideXlab platform.
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bioavailability of selenium from selenium enriched green Onions allium fistulosum and chives allium schoenoprasum after in vitro gastrointestinal digestion
International Journal of Food Sciences and Nutrition, 2007Co-Authors: Emese Kapolna, Peter FodorAbstract:Three sample preparation methods—proteolysis to determine the initial species distribution, and an in vitro gastric and gastrointestinal digestion to assess the bioavailability of selenium—were applied to extract the selenium from selenized green onion and chive samples. Ion exchange chromatography was coupled to a high-performance liquid chromatography–ICP-MS system to analyze the selenium species of Allium samples. The difference in the selenium accumulation capability of green Onions and chives was significant. Chive accumulated a one order of magnitude higher amount of selenium than did green onion. After proteolysis of both types of Allium plants, high amounts of organic selenium species such as MeSeCys, SeCys2 and SeMet became accessible. In the case of Se(VI)-enrichment, selenate was the main species in the proteolytic extract. After simulating the human digestion, the organic species were just slightly bioavailable compared with the results from proteolysis. The inorganic selenium content of the s...
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speciation analysis of selenium enriched green Onions allium fistulosum by hplc icp ms
Microchemical Journal, 2006Co-Authors: Emese Kapolna, Peter FodorAbstract:Abstract Green Onions (Allium fistulosum) enriched with 10 or 100 μg mL− 1 Se(IV) or SeMet were analyzed for total selenium and species distribution. Anion and cation exchange chromatographies were applied for the separation of selenium species with mass spectrometric detection. Two different sample preparation methods (NaOH and enzymatic) were compared from the Se extraction efficiency point of view. Total selenium concentration accumulated by the Onions reached the 200 μg g− 1 level expressed for dry weight when applying SeMet at a concentration of 100 μg mL− 1 as the source of Se. Speciation studies revealed that both in onion bulbs and leaves the predominant form of organic selenium is Se-methyl-selenocysteine (MeSeCys). When Se(IV) was applied for Se-enrichment at a concentration level of 100 μg mL− 1 both onion leaf and bulb contained a significant amount of inorganic selenium. An unknown compound was also detected.
Wenqing Xu - One of the best experts on this subject based on the ideXlab platform.
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application of pulsed light pl surfactant combination on inactivation of salmonella and apparent quality of green Onions
Lwt - Food Science and Technology, 2015Co-Authors: Wenqing Xu, Haiqiang Chen, Changqing WuAbstract:Abstract In our previous study using pulsed light (PL) and PL-sanitizer/surfactant to inactivate Escherichia coli O157:H7 on green Onions, the combination of PL and 1000 ppm of surfactant (sodium dodecyl sulfate, SDS) was more effective than single treatments. In this study, whether PL-surfactant combination would provide similar inactivation efficacy of Salmonella on green Onions was tested. Different surfactants (SDS and Tween 80) as well as different concentrations (10, 100 and 1000 ppm) of each surfactant combined with PL were tested. Survival populations of Salmonella and quality of green Onions (color and texture) were evaluated after treatments as well as during storage (15 days) at 4 °C. The results showed that PL-SDS and PL-Tween 80 combinations at various surfactant concentrations provided synergistic inactivation efficacy on green onion leaves (2.6–2.9 log10 CFU/g and 2.4–2.7 log10 CFU/g, respectively), but not on their stems (0.4–1.0 log10 CFU/g and 0.3–0.6 log10 CFU/g, respectively). PL-1000 ppm SDS combination negatively impacted color and texture of green Onions during 15 day storage at 4 °C. To consider both safety and quality of green Onions, PL-10 ppm SDS was selected since it showed similar Salmonella inactivation on green Onions as PL-1000 ppm SDS but did not affect quality of green Onions during shelf-life.
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decontamination of salmonella enterica typhimurium on green Onions using a new formula of sanitizer washing and pulsed uv light pl
Food Research International, 2014Co-Authors: Wenqing Xu, Changqing WuAbstract:Abstract Pathogenic bacteria such as Salmonella and Shigella flexneri have been linked to green onion contamination. This study was conducted to evaluate decontamination of Salmonella Typhimurium using a new formula of sanitizer washing (0.4 mg/mL thymol and five new formula sanitizers including 300 ppm H 2 O 2 + 4% SDS, 2 mg/mL citric acid + 4% SDS, 0.2 mg/mL thymol + 4% SDS, 0.2 mg/mL thymol + 2 mg/mL citric acid and 0.2 mg/mL thymol + 2 mg/mL acetic acid), pulsed UV light (PL) as well as synergy between the sanitizer wash and PL. New formula sanitizers based on decontamination efficacy of single washing solutions (organic acids, hydrogen peroxide (H 2 O 2 ), essential oil or surfactant) were applied to decontaminate spot inoculated green Onions. PL, the novel technique, alone has been applied to inactivate Salmonella on both dip and spot inoculated green Onions. Salmonella inactivation of PL–new formula sanitizer combinations on dip inoculated green Onions was investigated for their potential synergy. As a result, for spot inoculated green Onions, 0.4 mg/mL thymol individually and the five new formula sanitizers all achieved higher log reduction of Salmonella (4.5–5.3 log 10 CFU/g reduction) than the 200 ppm chlorine washing. These new formulas of sanitizer would be potential alternatives to chlorine. The 5 s dry PL (4.6 log 10 CFU/g) or 60 s wet PL treatment (3.6 log 10 CFU/g) was better or comparable as chlorine washing. The sanitizer combinations did not provide significantly higher log reduction than PL, and PL has the potential of being used in the green onion industry for decontamination purpose. For dip inoculated green Onions, none of our treatment provided > 0.8 log 10 CFU/g (0.6–0.8 log 10 CFU/g) reduction of Salmonella . As a result, the PL–new formula sanitizer combinations had no or minimal synergy to inactivate Salmonella dip inoculated on green Onions.
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decontamination of escherichia coli o157 h7 on green Onions using pulsed light pl and pl surfactant sanitizer combinations
International Journal of Food Microbiology, 2013Co-Authors: Wenqing Xu, Haiqiang Chen, Yaoxin Huang, Changqing WuAbstract:Abstract Imported green onion has been associated with three large outbreaks in the USA. Contamination has been found on both domestic and imported green Onions. The objective of our study was to investigate Escherichia coli O157:H7 inactivation efficacy of pulsed light (PL) as well as its combination with surfactant and/or sanitizers on green Onions. Green Onions were cut into two segments, stems and leaves, to represent two different matrixes. Stems were more difficult to be decontaminated. Spot and dip inoculation methods were compared and dipped inoculated green Onions were found to be more difficult to be decontaminated. Results showed that 5 s dry PL (samples were not immersed in water during PL treatment) and 60 s wet PL (samples were immersed in water and stirred during PL treatment) treatments provided promising inactivation efficacy (> 4 log 10 CFU/g) for spot inoculated stems and leaves. For dip inoculated green Onions, 60 s wet PL treatment was comparable with 100 ppm chlorine washing, demonstrating that PL could be used as an alternative to chlorine. To further increase the degree of microbial inactivation, combined treatments were applied. PL combined with surfactant (SDS) was found to be more effective than single treatments of PL, SDS, chlorine, citric acid, thymol, and hydrogen peroxide, and binary combined treatments of PL with one of those chemicals. Addition of chlorine or hydrogen peroxide to the PL–SDS combination did not further enhanced its microbial inactivation efficacy. The combination of PL and 1000 ppm of SDS reduced the E. coli O157:H7 populations dip inoculated on the stems and leaves of green Onions by 1.4 and 3.1 log 10 CFU/g, respectively. Our findings suggest that PL could potentially be used for decontamination of E. coli O157:H7 on green Onions, with wet PL added with SDS being the most effective PL treatment.
