Background: To preserve its nutritional properties, fish must have good sanitary quality. The objective of this study was to investigate some pathogens contaminating smoked, dried, and braised fish marketed in Ouagado...Background: To preserve its nutritional properties, fish must have good sanitary quality. The objective of this study was to investigate some pathogens contaminating smoked, dried, and braised fish marketed in Ouagadougou. Methodology: Potential pathogens of Enterobacteriaceae and Staphylococcus were screened in eight (8) species of processed fish. The investigation of the germs was carried out following the normative methods of microbiology. The identities of the strains were determined by API 20 E (BioMerieux S.A., France) and API STAPH (BioMerieux S.A., France) kits for Enterobacteriaceae and Staphylococcus species respectively. The uidA gene profile in Escherichia coli isolates was determined by simplex PCR. The identity of Staphylococcus aureus was confirmed by amplification of specific 23S rDNA regions and nuc gene profile with PCR. Results: A total of 235 fish samples were analyzed. A diversity of Enterobacteriaceae and Staphylococcus was detected. Twenty species of Enterobacteriaceae were identified among which, the most frequent were Escherichia coli, Salmonella sp, Raoultella ornithinolytica and Serratia odorifera, respectively in 22.6%, 4.3%, 28.9%, 17.4% of the samples analyzed. However, eleven species of Staphylococcus were identified among which, Staphylococcus xylosus, Staphylococcus aureus, Staphylococcus lugdunensis, and Staphylococcus sciuri were the most frequent with respective percentages of 47.7%, 23.4%, 12.8% and 10.6% of samples. For all the samples, the species frequently isolated were: Raoultella ornithinolytica, Escherichia coli, Serratia odorifera, Staphylococcus aureus, Staphylococcus xylosus, and Staphylococcus lugdunensis. The uidA gene specific to Escherichia coli was detected in 82.85% of strains (29/35). Amplification of the specific 23S rDNA region using staur primers was observed in 98% (49/50) of the isolated Staphylococcus aureus strains and the nuc gene was detected in 86% of Staphylococcus aureus strains. Conclusion: The isolated bacteria are potential pathogens involved in foodborne illnesses and intoxications. Effective sanitary safety systems must be implemented to guarantee the sanitary quality of fish supplied to consumers.展开更多
脉冲星搜寻是对脉冲星、引力波,以及对快速射电暴(Fast Radio Burst,简称FRB)等暂现源进行研究的基础。搜寻不仅可以扩大脉冲星样本,还可以发现极端性质的致密星。这有助于研究致密天体状态方程、星际介质、脉冲星导航、引力波探测等课...脉冲星搜寻是对脉冲星、引力波,以及对快速射电暴(Fast Radio Burst,简称FRB)等暂现源进行研究的基础。搜寻不仅可以扩大脉冲星样本,还可以发现极端性质的致密星。这有助于研究致密天体状态方程、星际介质、脉冲星导航、引力波探测等课题。目前,射电望远镜的单次巡天就可以产生百万数量级的脉冲星候选体。面对这些海量数据,仅仅依赖人工识别筛选,已不能满足数据的时效需求,更不能实现数据的实时处理。机器学习、计算机视觉应用等人工智能技术自诞生以来,其理论和技术已日益发展成熟,并已成功运用到脉冲星候选体筛选等射电天文研究领域。首先将介绍现有脉冲星搜寻的人工智能方法,再统计和分析已有脉冲星候选体筛选方法的性能,最后对FAST脉冲星候选体筛选工作进行展望。展开更多
The increasing demands of hydrogen and the recent discovery of large reserves of methane have prompted the conversion of methane to hydrogen.The challenges raised by intensive CO_(2) emission from the traditional conv...The increasing demands of hydrogen and the recent discovery of large reserves of methane have prompted the conversion of methane to hydrogen.The challenges raised by intensive CO_(2) emission from the traditional conversion of methane have provoked emission-free hydrogen production from methane.The catalytic decomposition of methane(CDM) to produce hydrogen and advanced carbon hence comes into consideration due to the short process and environmental benignity.Although many researchers have made considerable progress in CDM research on the laboratory scale,CDM is still in its infancy in industrialization.The history of its development,fundamental mechanisms,and recent research progress in catalysts and catalytic systems are herein highlighted.The problems of catalytic interface degradation are reviewed,focusing on deactivation from coke deposition in the CDM process.The introduction of a liquid phase interface which can in-situ remove carbon products provides a new strategy for this process.Furthermore,the challenges and prospects for future research into novel CDM catalysts or catalyst systems are included.展开更多
A bifunctional Co modified Fe3O4-Mn catalyst was prepared for Fischer-Tropsch synthesis (FTS). The influence of Co loading on the synergistic effect of Fe-Co as well as FTS performance over Fe1CoxMn1 catalysts was stu...A bifunctional Co modified Fe3O4-Mn catalyst was prepared for Fischer-Tropsch synthesis (FTS). The influence of Co loading on the synergistic effect of Fe-Co as well as FTS performance over Fe1CoxMn1 catalysts was studied. Incorporation of Co species into the Fe3O4-Mn catalyst promoted the reduction of iron oxides, increasing iron active sites during FTS. Moreover, the adding of Co species enhanced the electron transfer from Fe to Co metal, which strengthened the synergistic effect of Fe-Co, improving the catalytic performance. The Fe1CoxMn1 catalyst with higher Co loading promoted further the hydrogenation ability, favoring the shifting of the product distribution towards shorter hydrocarbons. Under optimized conditions of 280℃, 2.0 MPa and 3000 h-1, the highest yield of liquid fuels was obtained for the Fe1Co1Mn1 catalyst.展开更多
The study of the polymerization of a vegetable oil has a double interest;industrial but especially food. Industrial because polymers based on vegetable oil are in line with sustainable development;food because an oil ...The study of the polymerization of a vegetable oil has a double interest;industrial but especially food. Industrial because polymers based on vegetable oil are in line with sustainable development;food because an oil which polymerizes easily is a danger for human consumption. Three situations of <em>Cucurbita pepo</em> oil polymerization are carried out in the course of time, the factor retained being temperature. A monitoring of the evolution of the enthalpy by temperature variation by the DSC method allows to report the polymerization of this oil. It happens that a polymerization is triggered in the oil matrix but it seems to fade very quickly, this behavior is general because after sweeping a temperature range of 80<span style="white-space:nowrap;">°</span>C;100<span style="white-space:nowrap;">°</span>C and 150<span style="white-space:nowrap;">°</span>C adding different amounts of Irgacure: the<em> Cucurbita pepo</em> oil resists polymerization through its antioxidant compounds. However, a photolysis of this oil carried out over 8 days shows that it effectively polymerizes after 144 hours, which proves the great capacity of antioxidant compounds to protect this oil. The analyses carried out at 25<span style="white-space:nowrap;">°</span>C aim to simulate the behavior of the oil at room temperature. The results reveal good resistance to both thermochemical and photochemical polymerization, which opens up great prospects for its development in the food industry and in nutrition.展开更多
The paradigm shift of Hermitian systems into the non-Hermitian regime profoundly modifies inherent property of the topological systems, leading to various unprecedented effects such as the nonHermitian skin effect(NHS...The paradigm shift of Hermitian systems into the non-Hermitian regime profoundly modifies inherent property of the topological systems, leading to various unprecedented effects such as the nonHermitian skin effect(NHSE). In the past decade, the NHSE has been demonstrated in quantum, optical and acoustic systems. Beside those wave systems, the NHSE in diffusive systems has not yet been observed, despite recent abundant advances in the study of topological thermal diffusion. In this work,we design a thermal diffusion lattice based on a modified Su-Schrieffer-Heeger model and demonstrate the diffusive NHSE. In the proposed model, the asymmetric temperature field coupling inside each unit cell can be judiciously realized by appropriate configurations of structural parameters. We find that the temperature fields trend to concentrate toward the target boundary which is robust against initial excitation conditions. We thus experimentally demonstrated the NHSE in thermal diffusion and verified its robustness against various defects. Our work provides a platform for exploration of non-Hermitian physics in the diffusive systems, which has important applications in efficient heat collection, highly sensitive thermal sensing and others.展开更多
Single nucleotide polymorphisms (SNPs) are widely present and related to desirable agronomic traits in crops.clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated nuclease 9 (Cas9)-mediated bas...Single nucleotide polymorphisms (SNPs) are widely present and related to desirable agronomic traits in crops.clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated nuclease 9 (Cas9)-mediated base editors have been frequently used to correct defective alleles and create novel alleles by artificial evolution for rapid crop genetic improvement (Ma et al.,2021).展开更多
文摘Background: To preserve its nutritional properties, fish must have good sanitary quality. The objective of this study was to investigate some pathogens contaminating smoked, dried, and braised fish marketed in Ouagadougou. Methodology: Potential pathogens of Enterobacteriaceae and Staphylococcus were screened in eight (8) species of processed fish. The investigation of the germs was carried out following the normative methods of microbiology. The identities of the strains were determined by API 20 E (BioMerieux S.A., France) and API STAPH (BioMerieux S.A., France) kits for Enterobacteriaceae and Staphylococcus species respectively. The uidA gene profile in Escherichia coli isolates was determined by simplex PCR. The identity of Staphylococcus aureus was confirmed by amplification of specific 23S rDNA regions and nuc gene profile with PCR. Results: A total of 235 fish samples were analyzed. A diversity of Enterobacteriaceae and Staphylococcus was detected. Twenty species of Enterobacteriaceae were identified among which, the most frequent were Escherichia coli, Salmonella sp, Raoultella ornithinolytica and Serratia odorifera, respectively in 22.6%, 4.3%, 28.9%, 17.4% of the samples analyzed. However, eleven species of Staphylococcus were identified among which, Staphylococcus xylosus, Staphylococcus aureus, Staphylococcus lugdunensis, and Staphylococcus sciuri were the most frequent with respective percentages of 47.7%, 23.4%, 12.8% and 10.6% of samples. For all the samples, the species frequently isolated were: Raoultella ornithinolytica, Escherichia coli, Serratia odorifera, Staphylococcus aureus, Staphylococcus xylosus, and Staphylococcus lugdunensis. The uidA gene specific to Escherichia coli was detected in 82.85% of strains (29/35). Amplification of the specific 23S rDNA region using staur primers was observed in 98% (49/50) of the isolated Staphylococcus aureus strains and the nuc gene was detected in 86% of Staphylococcus aureus strains. Conclusion: The isolated bacteria are potential pathogens involved in foodborne illnesses and intoxications. Effective sanitary safety systems must be implemented to guarantee the sanitary quality of fish supplied to consumers.
文摘脉冲星搜寻是对脉冲星、引力波,以及对快速射电暴(Fast Radio Burst,简称FRB)等暂现源进行研究的基础。搜寻不仅可以扩大脉冲星样本,还可以发现极端性质的致密星。这有助于研究致密天体状态方程、星际介质、脉冲星导航、引力波探测等课题。目前,射电望远镜的单次巡天就可以产生百万数量级的脉冲星候选体。面对这些海量数据,仅仅依赖人工识别筛选,已不能满足数据的时效需求,更不能实现数据的实时处理。机器学习、计算机视觉应用等人工智能技术自诞生以来,其理论和技术已日益发展成熟,并已成功运用到脉冲星候选体筛选等射电天文研究领域。首先将介绍现有脉冲星搜寻的人工智能方法,再统计和分析已有脉冲星候选体筛选方法的性能,最后对FAST脉冲星候选体筛选工作进行展望。
基金the funding support from the National Natural Science Foundation of China(51722404,51674177,51804221 and 91845113)the National Key R&D Program of China(2018YFE0201703)+2 种基金the China Postdoctoral Science Foundation(2018M642906 and 2019T120684)the Fundamental Research Funds for the Central Universities(2042019kf0230)the Hubei Provincial Natural Science Foundation of China(2019CFA065)。
文摘The increasing demands of hydrogen and the recent discovery of large reserves of methane have prompted the conversion of methane to hydrogen.The challenges raised by intensive CO_(2) emission from the traditional conversion of methane have provoked emission-free hydrogen production from methane.The catalytic decomposition of methane(CDM) to produce hydrogen and advanced carbon hence comes into consideration due to the short process and environmental benignity.Although many researchers have made considerable progress in CDM research on the laboratory scale,CDM is still in its infancy in industrialization.The history of its development,fundamental mechanisms,and recent research progress in catalysts and catalytic systems are herein highlighted.The problems of catalytic interface degradation are reviewed,focusing on deactivation from coke deposition in the CDM process.The introduction of a liquid phase interface which can in-situ remove carbon products provides a new strategy for this process.Furthermore,the challenges and prospects for future research into novel CDM catalysts or catalyst systems are included.
基金supported by International Cooperation and Exchange Program of the National Natural Science Foundation of China(No.51861145102)Science and Technology Program of Shenzhen(No.JCYJ20180302153928437)Fundamental Research Fund for the Central Universities(No.2042019kf0221)
文摘A bifunctional Co modified Fe3O4-Mn catalyst was prepared for Fischer-Tropsch synthesis (FTS). The influence of Co loading on the synergistic effect of Fe-Co as well as FTS performance over Fe1CoxMn1 catalysts was studied. Incorporation of Co species into the Fe3O4-Mn catalyst promoted the reduction of iron oxides, increasing iron active sites during FTS. Moreover, the adding of Co species enhanced the electron transfer from Fe to Co metal, which strengthened the synergistic effect of Fe-Co, improving the catalytic performance. The Fe1CoxMn1 catalyst with higher Co loading promoted further the hydrogenation ability, favoring the shifting of the product distribution towards shorter hydrocarbons. Under optimized conditions of 280℃, 2.0 MPa and 3000 h-1, the highest yield of liquid fuels was obtained for the Fe1Co1Mn1 catalyst.
文摘The study of the polymerization of a vegetable oil has a double interest;industrial but especially food. Industrial because polymers based on vegetable oil are in line with sustainable development;food because an oil which polymerizes easily is a danger for human consumption. Three situations of <em>Cucurbita pepo</em> oil polymerization are carried out in the course of time, the factor retained being temperature. A monitoring of the evolution of the enthalpy by temperature variation by the DSC method allows to report the polymerization of this oil. It happens that a polymerization is triggered in the oil matrix but it seems to fade very quickly, this behavior is general because after sweeping a temperature range of 80<span style="white-space:nowrap;">°</span>C;100<span style="white-space:nowrap;">°</span>C and 150<span style="white-space:nowrap;">°</span>C adding different amounts of Irgacure: the<em> Cucurbita pepo</em> oil resists polymerization through its antioxidant compounds. However, a photolysis of this oil carried out over 8 days shows that it effectively polymerizes after 144 hours, which proves the great capacity of antioxidant compounds to protect this oil. The analyses carried out at 25<span style="white-space:nowrap;">°</span>C aim to simulate the behavior of the oil at room temperature. The results reveal good resistance to both thermochemical and photochemical polymerization, which opens up great prospects for its development in the food industry and in nutrition.
基金supported by the National Key Research and Development Program of China (2023YFB4604100, and 2023YFB4604800)the National Natural Science Foundation of China (92163123, 12304492, and 52250191)+1 种基金Zhejiang Provincial Natural Science Foundation of China (LZ24A050002)the China Postdoctoral Science Foundation (2023M733120)。
文摘The paradigm shift of Hermitian systems into the non-Hermitian regime profoundly modifies inherent property of the topological systems, leading to various unprecedented effects such as the nonHermitian skin effect(NHSE). In the past decade, the NHSE has been demonstrated in quantum, optical and acoustic systems. Beside those wave systems, the NHSE in diffusive systems has not yet been observed, despite recent abundant advances in the study of topological thermal diffusion. In this work,we design a thermal diffusion lattice based on a modified Su-Schrieffer-Heeger model and demonstrate the diffusive NHSE. In the proposed model, the asymmetric temperature field coupling inside each unit cell can be judiciously realized by appropriate configurations of structural parameters. We find that the temperature fields trend to concentrate toward the target boundary which is robust against initial excitation conditions. We thus experimentally demonstrated the NHSE in thermal diffusion and verified its robustness against various defects. Our work provides a platform for exploration of non-Hermitian physics in the diffusive systems, which has important applications in efficient heat collection, highly sensitive thermal sensing and others.
基金supported by the Biological Breeding-Major Projects (2023ZD04074)the Nanfan special project of the Chinese Academy of Agricultural Sciences (YBXM2313)+1 种基金the Hainan Seed Industry Laboratory (B23CJ0208)the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences。
文摘Single nucleotide polymorphisms (SNPs) are widely present and related to desirable agronomic traits in crops.clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated nuclease 9 (Cas9)-mediated base editors have been frequently used to correct defective alleles and create novel alleles by artificial evolution for rapid crop genetic improvement (Ma et al.,2021).
