Density functional theory calculations were carried out to study the thermal cracking for chrysene molecule to estimate the bond energies for breaking C 10b-C 11, C 11-H 11 and C4a-C 12a bonds as well as the activatio...Density functional theory calculations were carried out to study the thermal cracking for chrysene molecule to estimate the bond energies for breaking C 10b-C 11, C 11-H 11 and C4a-C 12a bonds as well as the activation energies. It was found that for C 10b-C 11 C11-HI 1 and C4a-C12a reactions, it is often possible to identify one pathway for bond breakage through the singlet or triplet states. Thus, the C 11-H11 and C11-C10b bonds ruptured in triplet state whilst the C12a-C4a in singlet state. Also, it was fond that the activation energy value for C4a-C12a bond breakage is lower than required for C10b-C11 and C11-H11 bonds that enquired the C4a-C12a bond ＂bridge bond＂ is a weaker and ruptured firstly in thermal cracking process. It seems that the characteristic planarity for polyaromatic hydrocarbons is an important factor to acquire the molecule structure the required stability along the reaction paths as well as the full octet rule and Clar＇s n-sextet structure, especially when chrysene molecular lose the property of planarity. The atomic charges supported the observation that the breaking bonds C10b-C11, CI1-H11 and C4a-C12a in triplet or singlet states. The configurations in transition state and the conformation for the end products reaction were explained and discussed.展开更多
The heat shock protein 70(HSP70)in fish plays a crucial role in various physiological and environmental stresses.To reveal the mechanisms of the HSP70 gene response to abiotic stress in mandarin fish(Siniperca chuatsi...The heat shock protein 70(HSP70)in fish plays a crucial role in various physiological and environmental stresses.To reveal the mechanisms of the HSP70 gene response to abiotic stress in mandarin fish(Siniperca chuatsi),we analyzed the HSP70 gene family in this species.There are 16 HSP70 genes in mandarin fish,and their protein three-dimensional structures were constructed.The aliphatic index of the 16 mandarin fish HSP70sranges from 73.50(HSPa4b)to 99.46(HSPa13),and all are hydrophilic proteins,with seven of them being unstable proteins.After exposure to chrysene,six HSP70 genes in the intestine,four in the liver,and four in the brain tissues exhibited significant expression changes.These findings reveal that chrysene exposure affects the physiological status of fish,and HSP70 genes may play a role in the chrysene exposure tolerance of the intestine,brain and liver in mandarin fish.展开更多
Crystal packing has strong influence on the charge mobility for organic semiconductors, so the elucidation of the structure-property relationship is important for the design of high-performance organic semiconductors....Crystal packing has strong influence on the charge mobility for organic semiconductors, so the elucidation of the structure-property relationship is important for the design of high-performance organic semiconductors. Halogen substitution has been shown to be a promising strategy to alter the crystal structure without significantly changing the molecular size in previous reports. This paper studies the influence of halogenation on charge transport in single crystals of chrysene derivatives from a theoretical standpoint. The structure-property relationship is first rationalized by investigating the reorganization energy and electronic coupling from the density functional theory calculations. Based on the Marcus charge transfer theory, the mobilities in the molecular monolayer are then calculated with the random walk simulation technique from which the angular resolution anisotropic mobilities are obtained on the fly. It is shown that the mobilities become much larger for holes than those for electrons in the molecular monolayer when the halogenation occurs. Furthermore, the intra-layer charge transport is little influenced by the inter-layer pathways in the single crystals of the halogenated chrysene derivatives, while the opposite case is shown for the crystal of the nonhalogenated chrysene derivative. The reason for the variations of charge transport is discussed theoretically.展开更多
Polycyclic aromatic hydrocarbons(PAHs)are classified as environmental and food contaminants,with several adverse health effects,especially genotoxic and carcinogenic actions.In processed meats,they are the major conta...Polycyclic aromatic hydrocarbons(PAHs)are classified as environmental and food contaminants,with several adverse health effects,especially genotoxic and carcinogenic actions.In processed meats,they are the major contaminants,especially those subjected to smoking processes.Considering that the population is exposed to PAHs through sev-eral routes,and that the ingestion of contaminated food is considered the main one,evaluating the concentrations of these contaminants in food becomes essential,as well as the exposure and risk to the population at different ages through ingestion of the evaluated products.In the current study,the levels of nine PAHs(PAH9)were measured in 205 processed meat products commercially available and with high consumption in Brazil.The methodology involved saponification,extraction with n-hexane,purification with solid-phase extraction(SPE)silica cartridges,and quantification by liquid chromatography with fluorescence detection.In general,83%of all samples were con-taminated with at least one of the studied PAHs,and the measured PAH9 levels ranged between<LOQ-108.24µg/kg.The highest mean of total PAHs was found in smoked sausage(108.24μg/kg),while the lowest content was found in ham(1.83μg/kg).Benzo[a]pyrene(BaP)and PAH4(benz[a]anthracene,chrysene,benzo[b]fluoranthene,and BaP)exceeded the maximum permissible limits of the European Union(EU)in three(1.5%)and 18 samples(8.7%),respec-tively.The results of margin of exposure results(MOE≥10,000)and incremental lifetime cancer risk(ILCR)values(10-6<ILCR<10-4)in all ten types of meat indicated there were low significant potential health problems related to meat products consumption for the Brazilian population.展开更多
文摘Density functional theory calculations were carried out to study the thermal cracking for chrysene molecule to estimate the bond energies for breaking C 10b-C 11, C 11-H 11 and C4a-C 12a bonds as well as the activation energies. It was found that for C 10b-C 11 C11-HI 1 and C4a-C12a reactions, it is often possible to identify one pathway for bond breakage through the singlet or triplet states. Thus, the C 11-H11 and C11-C10b bonds ruptured in triplet state whilst the C12a-C4a in singlet state. Also, it was fond that the activation energy value for C4a-C12a bond breakage is lower than required for C10b-C11 and C11-H11 bonds that enquired the C4a-C12a bond ＂bridge bond＂ is a weaker and ruptured firstly in thermal cracking process. It seems that the characteristic planarity for polyaromatic hydrocarbons is an important factor to acquire the molecule structure the required stability along the reaction paths as well as the full octet rule and Clar＇s n-sextet structure, especially when chrysene molecular lose the property of planarity. The atomic charges supported the observation that the breaking bonds C10b-C11, CI1-H11 and C4a-C12a in triplet or singlet states. The configurations in transition state and the conformation for the end products reaction were explained and discussed.
文摘The heat shock protein 70(HSP70)in fish plays a crucial role in various physiological and environmental stresses.To reveal the mechanisms of the HSP70 gene response to abiotic stress in mandarin fish(Siniperca chuatsi),we analyzed the HSP70 gene family in this species.There are 16 HSP70 genes in mandarin fish,and their protein three-dimensional structures were constructed.The aliphatic index of the 16 mandarin fish HSP70sranges from 73.50(HSPa4b)to 99.46(HSPa13),and all are hydrophilic proteins,with seven of them being unstable proteins.After exposure to chrysene,six HSP70 genes in the intestine,four in the liver,and four in the brain tissues exhibited significant expression changes.These findings reveal that chrysene exposure affects the physiological status of fish,and HSP70 genes may play a role in the chrysene exposure tolerance of the intestine,brain and liver in mandarin fish.
基金financially supported by the Major State Basic Research Development Programs of China (2011CBA00701)the National Natural Science Foundation of China (21003030 and 20973049)+1 种基金the Open Project of State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (HC201117)and the China Postdoctoral Science Foundation (20110490102)
文摘Crystal packing has strong influence on the charge mobility for organic semiconductors, so the elucidation of the structure-property relationship is important for the design of high-performance organic semiconductors. Halogen substitution has been shown to be a promising strategy to alter the crystal structure without significantly changing the molecular size in previous reports. This paper studies the influence of halogenation on charge transport in single crystals of chrysene derivatives from a theoretical standpoint. The structure-property relationship is first rationalized by investigating the reorganization energy and electronic coupling from the density functional theory calculations. Based on the Marcus charge transfer theory, the mobilities in the molecular monolayer are then calculated with the random walk simulation technique from which the angular resolution anisotropic mobilities are obtained on the fly. It is shown that the mobilities become much larger for holes than those for electrons in the molecular monolayer when the halogenation occurs. Furthermore, the intra-layer charge transport is little influenced by the inter-layer pathways in the single crystals of the halogenated chrysene derivatives, while the opposite case is shown for the crystal of the nonhalogenated chrysene derivative. The reason for the variations of charge transport is discussed theoretically.
基金supported by São Paulo Research Foundation,FAPESP,Brazil(No.2018/19005-6).
文摘Polycyclic aromatic hydrocarbons(PAHs)are classified as environmental and food contaminants,with several adverse health effects,especially genotoxic and carcinogenic actions.In processed meats,they are the major contaminants,especially those subjected to smoking processes.Considering that the population is exposed to PAHs through sev-eral routes,and that the ingestion of contaminated food is considered the main one,evaluating the concentrations of these contaminants in food becomes essential,as well as the exposure and risk to the population at different ages through ingestion of the evaluated products.In the current study,the levels of nine PAHs(PAH9)were measured in 205 processed meat products commercially available and with high consumption in Brazil.The methodology involved saponification,extraction with n-hexane,purification with solid-phase extraction(SPE)silica cartridges,and quantification by liquid chromatography with fluorescence detection.In general,83%of all samples were con-taminated with at least one of the studied PAHs,and the measured PAH9 levels ranged between<LOQ-108.24µg/kg.The highest mean of total PAHs was found in smoked sausage(108.24μg/kg),while the lowest content was found in ham(1.83μg/kg).Benzo[a]pyrene(BaP)and PAH4(benz[a]anthracene,chrysene,benzo[b]fluoranthene,and BaP)exceeded the maximum permissible limits of the European Union(EU)in three(1.5%)and 18 samples(8.7%),respec-tively.The results of margin of exposure results(MOE≥10,000)and incremental lifetime cancer risk(ILCR)values(10-6<ILCR<10-4)in all ten types of meat indicated there were low significant potential health problems related to meat products consumption for the Brazilian population.
