The Experts below are selected from a list of 60696 Experts worldwide ranked by ideXlab platform
Myran C. Sauer - One of the best experts on this subject based on the ideXlab platform.
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hole scavenging and photo stimulated recombination of electron hole pairs in aqueous tio2 nanoparticles
Journal of Physical Chemistry B, 2004Co-Authors: Ilya A Shkrob, Myran C. SauerAbstract:It is shown that 532 and 1064 nm laser photoexcitation of trapped electrons generated by 355 nm photolysis of aqueous titania (TiO2) nanoparticles causes rapid photobleaching of their absorbance band in the visible and near-IR. This photobleaching occurs within the duration of the laser pulse (3 ns fwhm); it is caused by photoinduced electron detrapping followed by rapid recombination of the resulting free electron and a trapped hole. The quantum yield for the electron photobleaching is ca. 0.28 for 532 nm and ca. 0.024 for 1064 nm photoexcitation. Complete separation of the spectral contributions from trapped electron and hole is demonstrated using glycerol as a selective hole Scavenger. When glycerol is added to the solution, some light-absorbing holes are scavenged promptly within the duration of the 355 nm photoexcitation pulse, some are scavenged at a slower rate over the first 200 ns after the 355 nm pulse, and the rest are not scavenged, even at high concentration of the Scavenger (>10 vol. %). A r...
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hole scavenging and photo stimulated recombination of electron hole pairs in aqueous tio2 nanoparticles
arXiv: Chemical Physics, 2004Co-Authors: Ilya A Shkrob, Myran C. SauerAbstract:It is shown that 532 nm and 1064 nm laser photoexcitation of trapped electrons generated by 355 nm photolysis of aqueous titania (TiO2) nanoparticles causes rapid photobleaching of their absorbance band in the visible and near IR. This photobleaching occurs within the duration of the laser pulse (3 ns FWHM); it is caused by photoinduced electron detrapping followed by rapid recombination of the resulting free electron and a trapped hole. The quantum yield for the electron photobleaching is ca. 0.28 for 532 nm and ca. 0.024 for 1064 nm photoexcitation. Complete separation of the spectral contributions from trapped electron and hole is demonstrated using glycerol as a selective hole Scavenger. When glycerol is added to the solution, some light-absorbing holes are scavenged promptly within the duration of the 355 nm photoexcitation pulse, some are scavenged at a slower rate over the first 200 ns after the 355 nm pulse, and the rest are not scavenged, even at high concentration of the Scavenger (> 10 vol %). A reaction with chemi- and physi- sorbed glycerol would account for the prompt and the slow hole decay, respectively. The implications of these results are discussed.
Hao Zhang - One of the best experts on this subject based on the ideXlab platform.
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melanoidins from coffee cocoa and bread are able to scavenge α dicarbonyl compounds under simulated physiological conditions
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Hao Zhang, Hui Zhang, Antonio Dario Troise, Vincenzo FoglianoAbstract:Free amino residues react with α-dicarbonyl compounds (DCs) contributing to the formation of advanced glycation end products (AGEs). Phenolic compounds can scavenge DCs, thus controlling the dietary carbonyl load. This study showed that high-molecular weight cocoa melanoidins (HMW-COM), HMW bread melanoidins (HMW-BM), and especially HMW coffee melanoidins (HMW-CM) are effective DC Scavengers. HMW-CM (1 mg/mL) scavenged more than 40% DCs within 2 h under simulated physiological conditions, suggesting some physiological relevance. Partial acid hydrolysis of HMW-CM decreased the dicarbonyl trapping capacity, demonstrating that the ability to react with glyoxal, methylglyoxal (MGO), and diacetyl was mainly because of polyphenols bound to macromolecules. Caffeic acid (CA) and 3-caffeoylquinic acid showed a DC-scavenging kinetic profile similar to that of HMW-CM, while mass spectrometry data confirmed that hydroxyalkylation and aromatic substitution reactions led to the formation of a stable adduct between CA and MGO. These findings corroborated the idea that antioxidant-rich indigestible materials could limit carbonyl stress and AGE formation across the gastrointestinal tract.
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melanoidins from coffee cocoa and bread are able to scavenge α dicarbonyl compounds under simulated physiological conditions
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Hao Zhang, Hui Zhang, Antonio Dario Troise, Vincenzo FoglianoAbstract:Free amino residues react with α-dicarbonyl compounds (DCs) contributing to the formation of advanced glycation end products (AGEs). Phenolic compounds can scavenge DCs, thus controlling the dietary carbonyl load. This study showed that high-molecular weight cocoa melanoidins (HMW-COM), HMW bread melanoidins (HMW-BM), and especially HMW coffee melanoidins (HMW-CM) are effective DC Scavengers. HMW-CM (1 mg/mL) scavenged more than 40% DCs within 2 h under simulated physiological conditions, suggesting some physiological relevance. Partial acid hydrolysis of HMW-CM decreased the dicarbonyl trapping capacity, demonstrating that the ability to react with glyoxal, methylglyoxal (MGO), and diacetyl was mainly because of polyphenols bound to macromolecules. Caffeic acid (CA) and 3-caffeoylquinic acid showed a DC-scavenging kinetic profile similar to that of HMW-CM, while mass spectrometry data confirmed that hydroxyalkylation and aromatic substitution reactions led to the formation of a stable adduct between CA a...
Vincenzo Fogliano - One of the best experts on this subject based on the ideXlab platform.
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melanoidins from coffee cocoa and bread are able to scavenge α dicarbonyl compounds under simulated physiological conditions
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Hao Zhang, Hui Zhang, Antonio Dario Troise, Vincenzo FoglianoAbstract:Free amino residues react with α-dicarbonyl compounds (DCs) contributing to the formation of advanced glycation end products (AGEs). Phenolic compounds can scavenge DCs, thus controlling the dietary carbonyl load. This study showed that high-molecular weight cocoa melanoidins (HMW-COM), HMW bread melanoidins (HMW-BM), and especially HMW coffee melanoidins (HMW-CM) are effective DC Scavengers. HMW-CM (1 mg/mL) scavenged more than 40% DCs within 2 h under simulated physiological conditions, suggesting some physiological relevance. Partial acid hydrolysis of HMW-CM decreased the dicarbonyl trapping capacity, demonstrating that the ability to react with glyoxal, methylglyoxal (MGO), and diacetyl was mainly because of polyphenols bound to macromolecules. Caffeic acid (CA) and 3-caffeoylquinic acid showed a DC-scavenging kinetic profile similar to that of HMW-CM, while mass spectrometry data confirmed that hydroxyalkylation and aromatic substitution reactions led to the formation of a stable adduct between CA and MGO. These findings corroborated the idea that antioxidant-rich indigestible materials could limit carbonyl stress and AGE formation across the gastrointestinal tract.
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melanoidins from coffee cocoa and bread are able to scavenge α dicarbonyl compounds under simulated physiological conditions
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Hao Zhang, Hui Zhang, Antonio Dario Troise, Vincenzo FoglianoAbstract:Free amino residues react with α-dicarbonyl compounds (DCs) contributing to the formation of advanced glycation end products (AGEs). Phenolic compounds can scavenge DCs, thus controlling the dietary carbonyl load. This study showed that high-molecular weight cocoa melanoidins (HMW-COM), HMW bread melanoidins (HMW-BM), and especially HMW coffee melanoidins (HMW-CM) are effective DC Scavengers. HMW-CM (1 mg/mL) scavenged more than 40% DCs within 2 h under simulated physiological conditions, suggesting some physiological relevance. Partial acid hydrolysis of HMW-CM decreased the dicarbonyl trapping capacity, demonstrating that the ability to react with glyoxal, methylglyoxal (MGO), and diacetyl was mainly because of polyphenols bound to macromolecules. Caffeic acid (CA) and 3-caffeoylquinic acid showed a DC-scavenging kinetic profile similar to that of HMW-CM, while mass spectrometry data confirmed that hydroxyalkylation and aromatic substitution reactions led to the formation of a stable adduct between CA a...
Ilya A Shkrob - One of the best experts on this subject based on the ideXlab platform.
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hole scavenging and photo stimulated recombination of electron hole pairs in aqueous tio2 nanoparticles
Journal of Physical Chemistry B, 2004Co-Authors: Ilya A Shkrob, Myran C. SauerAbstract:It is shown that 532 and 1064 nm laser photoexcitation of trapped electrons generated by 355 nm photolysis of aqueous titania (TiO2) nanoparticles causes rapid photobleaching of their absorbance band in the visible and near-IR. This photobleaching occurs within the duration of the laser pulse (3 ns fwhm); it is caused by photoinduced electron detrapping followed by rapid recombination of the resulting free electron and a trapped hole. The quantum yield for the electron photobleaching is ca. 0.28 for 532 nm and ca. 0.024 for 1064 nm photoexcitation. Complete separation of the spectral contributions from trapped electron and hole is demonstrated using glycerol as a selective hole Scavenger. When glycerol is added to the solution, some light-absorbing holes are scavenged promptly within the duration of the 355 nm photoexcitation pulse, some are scavenged at a slower rate over the first 200 ns after the 355 nm pulse, and the rest are not scavenged, even at high concentration of the Scavenger (>10 vol. %). A r...
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hole scavenging and photo stimulated recombination of electron hole pairs in aqueous tio2 nanoparticles
arXiv: Chemical Physics, 2004Co-Authors: Ilya A Shkrob, Myran C. SauerAbstract:It is shown that 532 nm and 1064 nm laser photoexcitation of trapped electrons generated by 355 nm photolysis of aqueous titania (TiO2) nanoparticles causes rapid photobleaching of their absorbance band in the visible and near IR. This photobleaching occurs within the duration of the laser pulse (3 ns FWHM); it is caused by photoinduced electron detrapping followed by rapid recombination of the resulting free electron and a trapped hole. The quantum yield for the electron photobleaching is ca. 0.28 for 532 nm and ca. 0.024 for 1064 nm photoexcitation. Complete separation of the spectral contributions from trapped electron and hole is demonstrated using glycerol as a selective hole Scavenger. When glycerol is added to the solution, some light-absorbing holes are scavenged promptly within the duration of the 355 nm photoexcitation pulse, some are scavenged at a slower rate over the first 200 ns after the 355 nm pulse, and the rest are not scavenged, even at high concentration of the Scavenger (> 10 vol %). A reaction with chemi- and physi- sorbed glycerol would account for the prompt and the slow hole decay, respectively. The implications of these results are discussed.
Joaquin Vicente - One of the best experts on this subject based on the ideXlab platform.
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consumption of big game remains by Scavengers a potential risk as regards disease transmission in central spain
Frontiers in Veterinary Science, 2018Co-Authors: Ricardo Carrascogarcia, Vidal Montoro, Patricia Barroso, Javier Perezolivares, Joaquin VicenteAbstract:Understanding the role that facultative Scavenger species may play in spreading infectious pathogens, and even becoming reservoirs for humans, domestic and wild ungulates or, on the contrary, preventing the spread of disease, requires a prior understanding of the pattern of carrion scavenging in specific scenarios. The objectives of this paper are: i) to describe the guild of vertebrate Scavengers and ii) to study the species-specific, habitat and management-related factors involved in the usage of gut piles in South Central Spain (SCS), a tuberculosis (TB) endemic area. We used camera trapping at 18 hunting piles on 7 hunting estates. A total of 8 bird and 5 mammal taxa were detected at the remains of hunting piles. The most frequently detected species in terms of number of gut piles visited (78%) and scavenged (61%) was the red fox Vulpes vulpes, followed by the griffon vulture Gyps fulvus (56% as regards both presence and scavenging) and the raven Corvus corax (61 and 39% as regards presence and scavenging, respectively). We evidenced that griffon vultures accounted for most of the scavenging activity in open habitats, while facultative mammal Scavengers, red fox and wild boar Sus scrofa made the highest contribution to scavenging in vegetation-covered habitats. In the case of wild boar, the gut piles deposited during the evening and night favoured higher rates of scavenging, while the opposite pattern was observed for griffons. Overall, our findings suggest that when disposing of hunting remains in areas of risk as regards disease transmission it is particularly important to consider the access that facultative mammals, and especially wild boar, have to material, while the presence of the resource needs to be safeguarded to protect specialist Scavengers of conservation value. These results are of particular relevance in the case of wild boar in the current context of re-emerging TB and emerging African Swine Fever (ASF) in Europe.
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Consumption of Big Game Remains by Scavengers: A Potential Risk as Regards Disease Transmission in Central Spain
Frontiers Media S.A., 2018Co-Authors: Ricardo Carrasco-garcia, Patricia Barroso, Javier Perez-olivares, Vidal Montoro, Joaquin VicenteAbstract:Understanding the role that facultative Scavenger species may play in spreading infectious pathogens, and even becoming reservoirs for humans, domestic and wild ungulates or, on the contrary, preventing the spread of disease, requires a prior understanding of the pattern of carrion scavenging in specific scenarios. The objectives of this paper are (i) to describe the guild of vertebrate Scavengers and (ii) to study the species-specific, habitat, and management-related factors involved in the usage of gut piles in South Central Spain (SCS), a tuberculosis (TB) endemic area. We used camera trapping at 18 hunting piles on seven hunting estates. A total of eight bird and five mammal taxa were detected at the remains of hunting piles. The most frequently detected species in terms of number of gut piles visited (78%) and scavenged (61%) was the red fox Vulpes vulpes, followed by the griffon vulture Gyps fulvus (56% as regards both presence and scavenging) and the raven Corvus corax (61 and 39% as regards presence and scavenging, respectively). We evidenced that griffon vultures accounted for most of the scavenging activity in open habitats, while facultative mammal Scavengers, red fox, and wild boar Sus scrofa made the highest contribution to scavenging in vegetation-covered habitats. In the case of wild boar, the gut piles deposited during the evening and night favored higher rates of scavenging, while the opposite pattern was observed for griffons. Overall, our findings suggest that when disposing of hunting remains in areas of risk as regards disease transmission it is particularly important to consider the access that facultative mammals, and especially wild boar, have to material, while the presence of the resource needs to be safeguarded to protect specialist Scavengers of conservation value. These results are of particular relevance in the case of wild boar in the current context of re-emerging TB and emerging African swine fever (ASF) in Europe
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from regional to global patterns in vertebrate Scavenger communities subsidized by big game hunting
Diversity and Distributions, 2015Co-Authors: Patricia Mateotomas, Pedro P Olea, Marcos Moleon, Joaquin Vicente, Francisco Botella, Nuria Selva, Javier Vinuela, Jose A SanchezzapataAbstract:Aim Anthropogenic food subsidies are increasingly present in ecosystems, but their impacts remain poorly understood. Big game hunting is a growing activity that annually subsidizes ecosystems with tonnes of carrion world-wide. By feeding on carrion, Scavengers support key ecosystem functions and services, becoming key vectors to transfer the impacts of human-mediated food subsidies across ecosystems. We characterize and compare the structure of vertebrate communities feeding on these subsidies, namely big game hunting remains, at a global scale. Location Global. Methods We collected data from a countrywide field study in Spain and broadened it up to nine regions in four continents by reviewing scientific literature. We analysed the structure of the Scavenger communities considering species composition, richness and scavenging frequency. Results Seventy-nine vertebrate species, 19% globally threatened, scavenged food subsidies from big game hunting world-wide. Scavenger richness (2.0– 11.0% of vertebrates/region) positively correlated with total vertebrate richness. Although Scavenger communities at hunting remains varied among regions, we describe a general structural pattern. Birds and mammals dominate consumption, with birds scavenging twice more frequently than mammals – but more mammal species scavenge compared to birds. Generalists dominate scavenging globally, especially where the presence of obligate Scavengers (vultures) and apex predators (e.g. wolves, hyenas, eagles) is low. Main conclusions Anthropogenic food from hunting subsidizes many vertebrate species from different trophic levels and conservation status and thus is expected to affect from populations to ecosystems. Obligate Scavengers and apex predators seem to play a key role structuring the Scavenger community through top-down mechanisms. The general structure of Scavenger communities we describe here provides a benchmark for comparisons of subsidized and non-subsidized communities. More data on the spatio-temporal availability of anthropogenic food subsidies and their consumption by Scavengers world-wide are needed to efficiently preserve biodiversity, and the associated ecological functions and services, in increasingly subsidized ecosystems.
