The sequence of the rice genome holds fundamental information for its biology, including physiology, genetics, development, and evolution, as well as information on many beneficial phenotypes of economic significance....The sequence of the rice genome holds fundamental information for its biology, including physiology, genetics, development, and evolution, as well as information on many beneficial phenotypes of economic significance. Using a "whole genome shotgun" approach, we have pro-duced a draft rice genome sequence of Oryza sativa ssp. in-dica, the major crop rice subspecies in China and many other regions of Asia. The draft genome sequence is constructed from over 4.3 million successful sequencing traces with an accumulative total length of 2214.9 Mb. The initial assembly of the non-redundant sequences reached 409.76 Mb in length, based on 3.30 million successful sequencing traces with a total length of 1797.4 Mb from an indica variant cultivar 93-11, giving an estimated coverage of 95.29% of the rice genome with an average base accuracy of higher than 99%. The coverage of the draft sequence, the randomness of the sequence distribution, and the consistency of BIG-ASSEM-BLER, a custom-designed software package展开更多
Integer overflow is a common vulnerability in Ethereum Smart Contracts(ESCs)and often causes huge economic losses.Smart contracts cannot be changed once it is deployed on the blockchain and thus demand further testing...Integer overflow is a common vulnerability in Ethereum Smart Contracts(ESCs)and often causes huge economic losses.Smart contracts cannot be changed once it is deployed on the blockchain and thus demand further testing.Mutation testing is a fault-based testing method that can effectively improve the sufficiency of a test for smart contracts.However,existing methods cannot efficiently perform mutation testing specifically for integer overflow in ESCs.Therefore,by analyzing integer overflow in ESCs,we propose five special mutation operators to address such vulnerability in terms of detecting sufficiency in ESC testing.An empirical study on 40 open-source ESCs is conducted to evaluate the effectiveness of the proposed mutation operators.Results show that(1)our proposed mutation operators can reproduce all 179 integer overflow vulnerabilities in 40 smart contracts,and the generated mutants have high compilation pass rate and integer overflow vulnerability generation rate;moreover,(2)the generated mutants can find the shortcomings of existing testing methods for integer overflow vulnerability,thereby providing effective support to improve the sufficiency of the test.展开更多
Creating lattice defects and alloying to produce strain effect in Pt-based bimetallic alloys are both effective methods to optimize the crystal and electronic structure and improve the electrocatalytic performance.Unf...Creating lattice defects and alloying to produce strain effect in Pt-based bimetallic alloys are both effective methods to optimize the crystal and electronic structure and improve the electrocatalytic performance.Unfortunately,the principles that govern the alkaline hydrogen evolution reaction(HER)performance remain unclear,which is detrimental to the rational design of efficient Pt-based electrocatalysts.Herein,PtNi alloys with different Pt/Ni ratios and edge dislocations were synthesized,and the effects of Pt/Ni composition and edge dislocations on the alkaline HER electrocatalytic activity of PtNi alloys were systematically studied.Combined experimental and theoretical investigations reveal that tuning Pt/Ni ratio results in only 1.1 times enhancements in Pt mass activity,whereas edge dislocations-induced extra tensile strain on Ni site and compressive strain on Pt site further boost the alkaline HER intrinsic activity at all Pt/Ni ratios.Impressively,the introduction of edge dislocations in PtNi alloys could break the limit of alloying in boosting Pt mass activity and result in up to 13.7-fold enhancement,in the case that Pt and Ni contents are nearly identical and thus edge dislocation density reaches the maximum.Fundamental mechanism studies demonstrate that the edge dislocation strategy could make a breakthrough in facilitating water dissociation kinetics of PtNi alloys.展开更多
Earlier, we reported that ST239 was the15-year predominant methicillin-resistant Staphylococcus aureus(MRSA) clone in China. In this study, MRSA strain CN79 belonging to ST239 and isolated from blood was used to deter...Earlier, we reported that ST239 was the15-year predominant methicillin-resistant Staphylococcus aureus(MRSA) clone in China. In this study, MRSA strain CN79 belonging to ST239 and isolated from blood was used to determine the whole genome sequence. Comparative genomics analysis was done between MRSA CN79and 25 sequenced S. aureus in the NCBI GenBank database. A total of 2,734 protein-encoding genes were identified in the MRSA CN79 genome, which carries 11antibiotic resistance genes and 65 virulence genes. Two prophages phiCN79A and phiNM3-like were found on the MRSA CN79 genome. MRSA CN79 carries 30 specific genes that are absent from the 25 sequenced S. aureus genomes. Most of them were prophage-related genes.Several antibiotic resistance genes, such as b-lactamase and ABC-type multidrug transport system gene, were located on the genomic island mSab. The antibiotic resistance genes, such as tet(M), ermA1, and blaZ, were also located on different transposons. The virulence genes sea,map, hlb, and sak are located on phiNM3-like prophage and the exotoxin genes are carried on the genomic island mSaa. These results suggest that ST239 MRSA strains are widespread owing to horizontal acquisition of the mobile genetic elements harbored antibiotic resistance genes and virulence genes in response to environmental selective pressures, such as antibiotics and the human immune system during evolution.展开更多
基金This work was sponsored by the Chinese Academy of Sciences, the Commission for Economy Planning, the Ministry of Science and Technology, the National Natural Science Foundation of China, Beijing Municipal Government, Zhejiang Provincial Government, and H
文摘The sequence of the rice genome holds fundamental information for its biology, including physiology, genetics, development, and evolution, as well as information on many beneficial phenotypes of economic significance. Using a "whole genome shotgun" approach, we have pro-duced a draft rice genome sequence of Oryza sativa ssp. in-dica, the major crop rice subspecies in China and many other regions of Asia. The draft genome sequence is constructed from over 4.3 million successful sequencing traces with an accumulative total length of 2214.9 Mb. The initial assembly of the non-redundant sequences reached 409.76 Mb in length, based on 3.30 million successful sequencing traces with a total length of 1797.4 Mb from an indica variant cultivar 93-11, giving an estimated coverage of 95.29% of the rice genome with an average base accuracy of higher than 99%. The coverage of the draft sequence, the randomness of the sequence distribution, and the consistency of BIG-ASSEM-BLER, a custom-designed software package
基金supported by National Key R&D Program of China(No.2018YFB1403400)the National Natural Science Foundation of China(No.61702544)+1 种基金Natural Science Foundation of Jiangsu Province,China(Nos.BK20160769 and BK20141072)China Postdoctoral Science Foundation(No.2016M603031)。
文摘Integer overflow is a common vulnerability in Ethereum Smart Contracts(ESCs)and often causes huge economic losses.Smart contracts cannot be changed once it is deployed on the blockchain and thus demand further testing.Mutation testing is a fault-based testing method that can effectively improve the sufficiency of a test for smart contracts.However,existing methods cannot efficiently perform mutation testing specifically for integer overflow in ESCs.Therefore,by analyzing integer overflow in ESCs,we propose five special mutation operators to address such vulnerability in terms of detecting sufficiency in ESC testing.An empirical study on 40 open-source ESCs is conducted to evaluate the effectiveness of the proposed mutation operators.Results show that(1)our proposed mutation operators can reproduce all 179 integer overflow vulnerabilities in 40 smart contracts,and the generated mutants have high compilation pass rate and integer overflow vulnerability generation rate;moreover,(2)the generated mutants can find the shortcomings of existing testing methods for integer overflow vulnerability,thereby providing effective support to improve the sufficiency of the test.
基金the National Natural Science Foundation of China(No.51822106).
文摘Creating lattice defects and alloying to produce strain effect in Pt-based bimetallic alloys are both effective methods to optimize the crystal and electronic structure and improve the electrocatalytic performance.Unfortunately,the principles that govern the alkaline hydrogen evolution reaction(HER)performance remain unclear,which is detrimental to the rational design of efficient Pt-based electrocatalysts.Herein,PtNi alloys with different Pt/Ni ratios and edge dislocations were synthesized,and the effects of Pt/Ni composition and edge dislocations on the alkaline HER electrocatalytic activity of PtNi alloys were systematically studied.Combined experimental and theoretical investigations reveal that tuning Pt/Ni ratio results in only 1.1 times enhancements in Pt mass activity,whereas edge dislocations-induced extra tensile strain on Ni site and compressive strain on Pt site further boost the alkaline HER intrinsic activity at all Pt/Ni ratios.Impressively,the introduction of edge dislocations in PtNi alloys could break the limit of alloying in boosting Pt mass activity and result in up to 13.7-fold enhancement,in the case that Pt and Ni contents are nearly identical and thus edge dislocation density reaches the maximum.Fundamental mechanism studies demonstrate that the edge dislocation strategy could make a breakthrough in facilitating water dissociation kinetics of PtNi alloys.
基金supported,in part,by the Beijing Natural Science Foundation(7102130)the Program for New Century Excellent Talents in University(NCET-10-0205)+1 种基金the National Natural Science Foundation of China(31100106)Key Projects in the National Science&Technology Pillar Program(2012EP001002)
文摘Earlier, we reported that ST239 was the15-year predominant methicillin-resistant Staphylococcus aureus(MRSA) clone in China. In this study, MRSA strain CN79 belonging to ST239 and isolated from blood was used to determine the whole genome sequence. Comparative genomics analysis was done between MRSA CN79and 25 sequenced S. aureus in the NCBI GenBank database. A total of 2,734 protein-encoding genes were identified in the MRSA CN79 genome, which carries 11antibiotic resistance genes and 65 virulence genes. Two prophages phiCN79A and phiNM3-like were found on the MRSA CN79 genome. MRSA CN79 carries 30 specific genes that are absent from the 25 sequenced S. aureus genomes. Most of them were prophage-related genes.Several antibiotic resistance genes, such as b-lactamase and ABC-type multidrug transport system gene, were located on the genomic island mSab. The antibiotic resistance genes, such as tet(M), ermA1, and blaZ, were also located on different transposons. The virulence genes sea,map, hlb, and sak are located on phiNM3-like prophage and the exotoxin genes are carried on the genomic island mSaa. These results suggest that ST239 MRSA strains are widespread owing to horizontal acquisition of the mobile genetic elements harbored antibiotic resistance genes and virulence genes in response to environmental selective pressures, such as antibiotics and the human immune system during evolution.
