The nanoscale zinc oxide(n-ZnO)was used in food packages due to its superior antibac terial activity,resulting in potential intake of n-ZnO through the digestive system,wherein n-ZnO interacted with saliva.In recent,f...The nanoscale zinc oxide(n-ZnO)was used in food packages due to its superior antibac terial activity,resulting in potential intake of n-ZnO through the digestive system,wherein n-ZnO interacted with saliva.In recent,facet engineering,a technique for controlling the exposed facets,was applied to n-ZnO,whereas risk of n-ZnO with specific exposed facets in saliva was ignored.ZnO nanoflakes(ZnO-0001)and nanoneedles(ZnO-1010)with the pri mary exposed facets of{0001}and{1010}respectively were prepared in this study,investigat ing stability and toxicity of ZnO-0001 and ZnO-1010 in synthetic saliva.Both ZnO-0001 and ZnO-1010 partially transformed into amorphous Zn_(3)(PO_(4))_(2)within 1 hr in the saliva even containing orgnaic components,forming a ZnO-Zn_(3)(PO_(4))_(2)core-shell structure.Neverthe less,ZnO-1010 relative to ZnO-0001 would likely transform into Zn_(3)(PO_(4))_(2),being attributed to superior dissolution of{1010}facet due to its lower vacancy formation energy(1.15 eV than{0001}facet(3.90 eV)).The toxicity of n-ZnO to Caco-2 cells was also dependent on the primary exposed facet;ZnO-0001 caused cell toxicity through oxidative stress,whereas ZnO-1010 resulted in lower cells viability than ZnO-0001 through oxidative stress and mem brane damage.Density functional theory calculations illustrated that·O_(2)^(-)was formed and released on{1010}facet,yet O_(2)^(2-)instead of·O_(2)^(-)was generated on{0001}facet,leading to low oxidative stress from ZnO-0001.All findings demonstrated that stability and toxicity of n-ZnO were dependent on the primary exposed facet,improving our understanding o health risk of nanomaterials.展开更多
Oral English is an important part in higher vocational English teaching. The 2021 edition of "English Curriculum Standard for Higher Vocational Education" puts forward new requirements for higher vocational ...Oral English is an important part in higher vocational English teaching. The 2021 edition of "English Curriculum Standard for Higher Vocational Education" puts forward new requirements for higher vocational students oral English ability. The document proposes that "students can use English language knowledge and skills to accurately understand and express information, views and feelings, and communicate effectively orally and in writing." Under such requirements, the traditional final examination evaluation method cannot meet the challenges of the new era. The new evaluation method is intervention dynamic evaluation, which pays attention to the communication between teachers and students and interactive feedback, and continuously adjusts the dynamic form of teaching methods through feedback. Through the intervention dynamic evaluation experiment of oral courses, the author observes whether the new evaluation method can reduce students learning anxiety and improve learning efficiency.展开更多
With the development of economy and society, the number of automobiles in our country is increasing day by day. As the population base of our country is large, the number of automobiles increases gradually after the n...With the development of economy and society, the number of automobiles in our country is increasing day by day. As the population base of our country is large, the number of automobiles increases gradually after the national income increases. More and more automobiles result in more and more air pollution caused by the increase of exhaust emissions. Nowadays, automobile exhaust pollution has become a concern of governments and people in various countries, and the importance of environmental protection has been recognized. In order to survive better, we must take the road of sustainable development. The pollution problem caused by automobile emissions is very serious in our country. Severe smog weather has emerged, which is caused by various unfavorable factors. Analysis of sources of fine particulate matter in 15 cities of Beijing, Tianjin and Shanghai shows that mobile sources account for 13.5%~41.0% of the local pollution sources. Facing the severe situation of air pollution control, it is imperative to control automobile exhaust emissions. We can now control the vehicle emissions for a certain period of time, and carry out scientific control through a large amount of data, so as to achieve the purpose of controlling air pollution. At present, China's air pollution problem is serious. How to reduce the exhaust pollution caused by vehicle exhaust emissions is a problem that needs to be studied, discussed and solved. Based on the mechanism and case studies, this paper studies the formation of vehicle exhaust and how to effectively reduce it, providing scientific and practical suggestions for effective reduction and prevention.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21806141,22021003,and 21976163)。
文摘The nanoscale zinc oxide(n-ZnO)was used in food packages due to its superior antibac terial activity,resulting in potential intake of n-ZnO through the digestive system,wherein n-ZnO interacted with saliva.In recent,facet engineering,a technique for controlling the exposed facets,was applied to n-ZnO,whereas risk of n-ZnO with specific exposed facets in saliva was ignored.ZnO nanoflakes(ZnO-0001)and nanoneedles(ZnO-1010)with the pri mary exposed facets of{0001}and{1010}respectively were prepared in this study,investigat ing stability and toxicity of ZnO-0001 and ZnO-1010 in synthetic saliva.Both ZnO-0001 and ZnO-1010 partially transformed into amorphous Zn_(3)(PO_(4))_(2)within 1 hr in the saliva even containing orgnaic components,forming a ZnO-Zn_(3)(PO_(4))_(2)core-shell structure.Neverthe less,ZnO-1010 relative to ZnO-0001 would likely transform into Zn_(3)(PO_(4))_(2),being attributed to superior dissolution of{1010}facet due to its lower vacancy formation energy(1.15 eV than{0001}facet(3.90 eV)).The toxicity of n-ZnO to Caco-2 cells was also dependent on the primary exposed facet;ZnO-0001 caused cell toxicity through oxidative stress,whereas ZnO-1010 resulted in lower cells viability than ZnO-0001 through oxidative stress and mem brane damage.Density functional theory calculations illustrated that·O_(2)^(-)was formed and released on{1010}facet,yet O_(2)^(2-)instead of·O_(2)^(-)was generated on{0001}facet,leading to low oxidative stress from ZnO-0001.All findings demonstrated that stability and toxicity of n-ZnO were dependent on the primary exposed facet,improving our understanding o health risk of nanomaterials.
文摘Oral English is an important part in higher vocational English teaching. The 2021 edition of "English Curriculum Standard for Higher Vocational Education" puts forward new requirements for higher vocational students oral English ability. The document proposes that "students can use English language knowledge and skills to accurately understand and express information, views and feelings, and communicate effectively orally and in writing." Under such requirements, the traditional final examination evaluation method cannot meet the challenges of the new era. The new evaluation method is intervention dynamic evaluation, which pays attention to the communication between teachers and students and interactive feedback, and continuously adjusts the dynamic form of teaching methods through feedback. Through the intervention dynamic evaluation experiment of oral courses, the author observes whether the new evaluation method can reduce students learning anxiety and improve learning efficiency.
文摘With the development of economy and society, the number of automobiles in our country is increasing day by day. As the population base of our country is large, the number of automobiles increases gradually after the national income increases. More and more automobiles result in more and more air pollution caused by the increase of exhaust emissions. Nowadays, automobile exhaust pollution has become a concern of governments and people in various countries, and the importance of environmental protection has been recognized. In order to survive better, we must take the road of sustainable development. The pollution problem caused by automobile emissions is very serious in our country. Severe smog weather has emerged, which is caused by various unfavorable factors. Analysis of sources of fine particulate matter in 15 cities of Beijing, Tianjin and Shanghai shows that mobile sources account for 13.5%~41.0% of the local pollution sources. Facing the severe situation of air pollution control, it is imperative to control automobile exhaust emissions. We can now control the vehicle emissions for a certain period of time, and carry out scientific control through a large amount of data, so as to achieve the purpose of controlling air pollution. At present, China's air pollution problem is serious. How to reduce the exhaust pollution caused by vehicle exhaust emissions is a problem that needs to be studied, discussed and solved. Based on the mechanism and case studies, this paper studies the formation of vehicle exhaust and how to effectively reduce it, providing scientific and practical suggestions for effective reduction and prevention.
