How to design and organize the implementation of teaching is an important consideration for the quality of the course.This paper takes the“Digital Logic Design”course as an example,and carries out teaching design an...How to design and organize the implementation of teaching is an important consideration for the quality of the course.This paper takes the“Digital Logic Design”course as an example,and carries out teaching design and practice based on the blended teaching mode.By adopting various forms such as MOOC+SPOC+theme seminars,beneficial explorations have been made in improving students’autonomous learning ability,strengthening engineering literacy,and cultivating innovation ability.展开更多
Virtual simulation experiment teaching gradually becomes the trend of the computer-related education practice.Through analyzing the problems existed in current computer experiment teaching,this paper proposes the idea...Virtual simulation experiment teaching gradually becomes the trend of the computer-related education practice.Through analyzing the problems existed in current computer experiment teaching,this paper proposes the idea of building virtual simulation experiment platform based on 3R-4A computer system and clarifies the design technology,including frame,characteristic and innovation,resource sharing and management,condition protection and so on.展开更多
This paper proposes a practical teaching approach in C programing language based on project learning.Having performing experimental teaching in class,this approach obtains pretty good teaching results,although it pres...This paper proposes a practical teaching approach in C programing language based on project learning.Having performing experimental teaching in class,this approach obtains pretty good teaching results,although it presents some flaws.This paper briefs the process of teaching,analyses the problems which are found during teaching and provides the solutions accordingly.展开更多
In this work,we demonstrate the spectral manipulation in an ultrafast fiber laser system that generates ultrashort pulses with a repetition rate of 1.2 GHz and two switchable modes—a 1064-nm fundamental laser mode wi...In this work,we demonstrate the spectral manipulation in an ultrafast fiber laser system that generates ultrashort pulses with a repetition rate of 1.2 GHz and two switchable modes—a 1064-nm fundamental laser mode with a maximum output power of 66.6 W,and a 1125-nm Raman laser mode with a maximum output power of 17.23 W.The pulse width,beam quality,and power stability are carefully characterized.We also investigate a method to switch between the two modes by manipulating the duty cycle of the modulation signal.It is anticipated that this bi-mode ultrafast fiber laser system can be a promising ultrafast laser source for frontier applications,such as micromachining,bioimaging,and spectroscopy.展开更多
On May 21,2021,a local case of coronavirus disease 2019(COVID-19)was confirmed in a 75-year-old woman(experienced onset of symptoms on May 18)in Liwan District,Guangzhou City,Guangdong Province,China.The number of inf...On May 21,2021,a local case of coronavirus disease 2019(COVID-19)was confirmed in a 75-year-old woman(experienced onset of symptoms on May 18)in Liwan District,Guangzhou City,Guangdong Province,China.The number of infections has increased in the following 10 days and led to 5 generations of transmission.展开更多
Bat coronavirus(CoV)RaTG13 shares the highest genome sequence identity with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)among all known coronaviruses,and also uses human angiotensin converting enzyme 2(...Bat coronavirus(CoV)RaTG13 shares the highest genome sequence identity with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)among all known coronaviruses,and also uses human angiotensin converting enzyme 2(hACE2)for virus entry.Thus,SARS-CoV-2 is thought to have originated from bat.However,whether SARS-CoV-2 emerged from bats directly or through an intermediate host remains elusive.Here,we found that Rhinolophus affinis bat ACE2(Ra ACE2)is an entry receptor for both SARSCoV-2 and Ra TG13,although the binding of Ra ACE2 to the receptor-binding domain(RBD)of SARSCoV-2 is markedly weaker than that of h ACE2.We further evaluated the receptor activities of ACE2 s from additional 16 diverse animal species for Ra TG13,SARS-CoV,and SARS-CoV-2 in terms of S protein binding,membrane fusion,and pseudovirus entry.We found that the Ra TG13 spike(S)protein is significantly less fusogenic than SARS-CoV and SARS-CoV-2,and seven out of sixteen different ACE2 s function as entry receptors for all three viruses,indicating that all three viruses might have broad host rages.Of note,Ra TG13 S pseudovirions can use mouse,but not pangolin ACE2,for virus entry,whereas SARS-CoV-2 S pseudovirions can use pangolin,but not mouse,ACE2 enter cells efficiently.Mutagenesis analysis revealed that residues 484 and 498 in Ra TG13 and SARS-CoV-2 S proteins play critical roles in recognition of mouse and human ACE2 s.Finally,two polymorphous Rhinolophous sinicus bat ACE2 s showed different susceptibilities to virus entry by Ra TG13 and SARS-CoV-2 S pseudovirions,suggesting possible coevolution.Our results offer better understanding of the mechanism of coronavirus entry,host range,and virushost coevolution.展开更多
What is already known about this topic?The Omicron variant has been listed as a variant of concern,but the characteristics still remain unclear.What is added by this report?The vaccinated proportion of 65 imported cor...What is already known about this topic?The Omicron variant has been listed as a variant of concern,but the characteristics still remain unclear.What is added by this report?The vaccinated proportion of 65 imported coronavirus disease 2019 cases that were infected with Omicron variant in this study was 89.23%,which was higher than Delta cases.Most imported cases infected with Omicron were tested positive using polymerase chain reaction after entering Guangdong within 3 days,a shorter period than Delta.展开更多
Tryptamine-derived natural products have been discovered from different sources including animals, plants and bacteria,and they show various biological activities. However, they are not discovered widely compared with...Tryptamine-derived natural products have been discovered from different sources including animals, plants and bacteria,and they show various biological activities. However, they are not discovered widely compared with the large amounts of tryptamine derivatives generated by chemical synthesis. We here report the discovery of five tryptamine-derived natural products(1-5) and one known polyketide 6 from Bacillus sp. PKU-TA00001. Compounds 1 and 2 are new compounds featuring methyl-hexanamide moieties, compound 4 is first discovered as a natural product, and 3 and 4’s NMR data are first provided. All compounds showed MIC(minimum inhibitory concentration) values higher than 50 μM against several Gram-positive and negative strains, and showed no cytotoxicity at the concentration of 100 μM against the human cancer cell lines A549, HCT-8 and MCF-7. The discovery of 1-4 expands the structural diversity of tryptamine-derived natural products, and sets the stage for revealing their biosynthetic mechanisms and biological activities in the future.展开更多
Security surveillance is widely used in daily life.For nighttime or complicated monitoring environments,this article proposes an infrared pedestrian monitoring based on YOLOv3.In the original YOLOv3 network structure,...Security surveillance is widely used in daily life.For nighttime or complicated monitoring environments,this article proposes an infrared pedestrian monitoring based on YOLOv3.In the original YOLOv3 network structure,two aspects of optimization were made.One was to optimize the scale in the residual structure,and the rich features of the deconvolution layer were added to the original residual structure.The other was to use the DenseNet network to enhance the features.The optimization of fusion ability and delivery ability effectively improves the detection ability for small targets,and the pedestrian detection performance based on infrared images.After comparative testing,compared with YOLOv3,the overall mean average precision is improved by 4.39%to 78.86%.展开更多
文摘How to design and organize the implementation of teaching is an important consideration for the quality of the course.This paper takes the“Digital Logic Design”course as an example,and carries out teaching design and practice based on the blended teaching mode.By adopting various forms such as MOOC+SPOC+theme seminars,beneficial explorations have been made in improving students’autonomous learning ability,strengthening engineering literacy,and cultivating innovation ability.
文摘Virtual simulation experiment teaching gradually becomes the trend of the computer-related education practice.Through analyzing the problems existed in current computer experiment teaching,this paper proposes the idea of building virtual simulation experiment platform based on 3R-4A computer system and clarifies the design technology,including frame,characteristic and innovation,resource sharing and management,condition protection and so on.
文摘This paper proposes a practical teaching approach in C programing language based on project learning.Having performing experimental teaching in class,this approach obtains pretty good teaching results,although it presents some flaws.This paper briefs the process of teaching,analyses the problems which are found during teaching and provides the solutions accordingly.
基金supported by the NSFC Development of National Major Scientific Research Instrument(No.61927816)the Introduced Innovative Team Project of Guangdong Pearl River Talents Program(No.2021ZT09Z109)+5 种基金the Natural Science Foundation of Guangdong Province(No.2021B1515020074)the Mobility Programme of the Sino-German(No.M-0296)the Double First Class Initiative(No.D6211170)the National Natural Science Foundation of China(Nos.U1609219 and 62235014)the Science and Technology Project of Guangdong(No.2020B1212060002)the Key R&D Program of Guangzhou(No.202007020003)。
文摘In this work,we demonstrate the spectral manipulation in an ultrafast fiber laser system that generates ultrashort pulses with a repetition rate of 1.2 GHz and two switchable modes—a 1064-nm fundamental laser mode with a maximum output power of 66.6 W,and a 1125-nm Raman laser mode with a maximum output power of 17.23 W.The pulse width,beam quality,and power stability are carefully characterized.We also investigate a method to switch between the two modes by manipulating the duty cycle of the modulation signal.It is anticipated that this bi-mode ultrafast fiber laser system can be a promising ultrafast laser source for frontier applications,such as micromachining,bioimaging,and spectroscopy.
基金The Key-Area Research and Development Program of Guangdong Province(2019B111103001,2020B111107001)The National Natural Science Foundation of China(No.82041030).
文摘On May 21,2021,a local case of coronavirus disease 2019(COVID-19)was confirmed in a 75-year-old woman(experienced onset of symptoms on May 18)in Liwan District,Guangzhou City,Guangdong Province,China.The number of infections has increased in the following 10 days and led to 5 generations of transmission.
基金supported by the National Key R&D Program of China(2020YFA0707600 and 2020YFC0841000)the National Natural Science Foundation of China(31970171 and 31670164)the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences(2016-12M-1-014 and 2020-12M-Co V19-010)。
文摘Bat coronavirus(CoV)RaTG13 shares the highest genome sequence identity with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)among all known coronaviruses,and also uses human angiotensin converting enzyme 2(hACE2)for virus entry.Thus,SARS-CoV-2 is thought to have originated from bat.However,whether SARS-CoV-2 emerged from bats directly or through an intermediate host remains elusive.Here,we found that Rhinolophus affinis bat ACE2(Ra ACE2)is an entry receptor for both SARSCoV-2 and Ra TG13,although the binding of Ra ACE2 to the receptor-binding domain(RBD)of SARSCoV-2 is markedly weaker than that of h ACE2.We further evaluated the receptor activities of ACE2 s from additional 16 diverse animal species for Ra TG13,SARS-CoV,and SARS-CoV-2 in terms of S protein binding,membrane fusion,and pseudovirus entry.We found that the Ra TG13 spike(S)protein is significantly less fusogenic than SARS-CoV and SARS-CoV-2,and seven out of sixteen different ACE2 s function as entry receptors for all three viruses,indicating that all three viruses might have broad host rages.Of note,Ra TG13 S pseudovirions can use mouse,but not pangolin ACE2,for virus entry,whereas SARS-CoV-2 S pseudovirions can use pangolin,but not mouse,ACE2 enter cells efficiently.Mutagenesis analysis revealed that residues 484 and 498 in Ra TG13 and SARS-CoV-2 S proteins play critical roles in recognition of mouse and human ACE2 s.Finally,two polymorphous Rhinolophous sinicus bat ACE2 s showed different susceptibilities to virus entry by Ra TG13 and SARS-CoV-2 S pseudovirions,suggesting possible coevolution.Our results offer better understanding of the mechanism of coronavirus entry,host range,and virushost coevolution.
基金The Key-Area Research and Development Program of Guangdong Province(2019B111103001).
文摘What is already known about this topic?The Omicron variant has been listed as a variant of concern,but the characteristics still remain unclear.What is added by this report?The vaccinated proportion of 65 imported coronavirus disease 2019 cases that were infected with Omicron variant in this study was 89.23%,which was higher than Delta cases.Most imported cases infected with Omicron were tested positive using polymerase chain reaction after entering Guangdong within 3 days,a shorter period than Delta.
基金National Natural Science Foundation of China(Grant No.81673332,81573326,81741148)
文摘Tryptamine-derived natural products have been discovered from different sources including animals, plants and bacteria,and they show various biological activities. However, they are not discovered widely compared with the large amounts of tryptamine derivatives generated by chemical synthesis. We here report the discovery of five tryptamine-derived natural products(1-5) and one known polyketide 6 from Bacillus sp. PKU-TA00001. Compounds 1 and 2 are new compounds featuring methyl-hexanamide moieties, compound 4 is first discovered as a natural product, and 3 and 4’s NMR data are first provided. All compounds showed MIC(minimum inhibitory concentration) values higher than 50 μM against several Gram-positive and negative strains, and showed no cytotoxicity at the concentration of 100 μM against the human cancer cell lines A549, HCT-8 and MCF-7. The discovery of 1-4 expands the structural diversity of tryptamine-derived natural products, and sets the stage for revealing their biosynthetic mechanisms and biological activities in the future.
基金the Fundamental Research Funds for the Local Universities of Hei longjiang Province in 2018(Grant No.2018-KYYWF-1189)Shanghai Aerospace Science and Technology Innovation Fund(Grand No.SAST2017-104).
文摘Security surveillance is widely used in daily life.For nighttime or complicated monitoring environments,this article proposes an infrared pedestrian monitoring based on YOLOv3.In the original YOLOv3 network structure,two aspects of optimization were made.One was to optimize the scale in the residual structure,and the rich features of the deconvolution layer were added to the original residual structure.The other was to use the DenseNet network to enhance the features.The optimization of fusion ability and delivery ability effectively improves the detection ability for small targets,and the pedestrian detection performance based on infrared images.After comparative testing,compared with YOLOv3,the overall mean average precision is improved by 4.39%to 78.86%.
