The rapid development of rare earth metal elements in the field of photocatalysis is due to their excellent optical and physicochemical properties.Benefiting from the unique external electronic structure of 4f_15d_16S...The rapid development of rare earth metal elements in the field of photocatalysis is due to their excellent optical and physicochemical properties.Benefiting from the unique external electronic structure of 4f_15d_16S_2,superior electronegativity of the 4f orbitals,and strong oxygen storage-release ability in Ce^(4+)/Ce^(3+)reversible pairs,cerium dioxide(CeO_(2))has attracted increasing interest from scientists.Nevertheless,the fast recombination of photoinduced electron-hole pairs and wide energy band gap of bare CeO_(2)significantly limit its practical applications.To overcome the above drawbacks,the construction of heterojunctions has been developed to broaden the absorption spectrum and accelerate the charge transfer.This review presents a mini-review of the synthesis of CeO_(2)-based heterojunctions including typeⅡ,Z-scheme,and S-scheme photocatalysts,as well as the corresponding applications in photocatalytic bactericidal and antitumor therapy.Finally,the latest advancements and potential perspectives on their future development are also discussed.展开更多
Background:Since December 2019,an outbreak of the Corona Virus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus(SARS-CoV-2)in Wuhan,China,has become a public health emergency of internatio...Background:Since December 2019,an outbreak of the Corona Virus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus(SARS-CoV-2)in Wuhan,China,has become a public health emergency of international concern.The high fatality of aged cases caused by SARS-CoV-2 was a need to explore the possible age-related phenomena with non-human primate models.Methods:Three 3-5 years old and two 15 years old rhesus macaques were intratracheally infected with SARS-CoV-2,and then analyzed by clinical signs,viral replication,chest X-ray,histopathological changes and immune response.Results:Viral replication of nasopharyngeal swabs,anal swabs and lung in old monkeys was more active than that in young monkeys for 14 days after SARS-CoV-2 challenge.Monkeys developed typical interstitial pneumonia characterized by thickened alveolar septum accompanied with inflammation and edema,notably,old monkeys exhibited diffuse severe interstitial pneumonia.Viral antigens were detected mainly in alveolar epithelial cells and macrophages.Conclusion:SARS-CoV-2 caused more severe interstitial pneumonia in old monkeys than that in young monkeys.Rhesus macaque models infected with SARS-CoV-2 provided insight into the pathogenic mechanism and facilitated the development of vaccines and therapeutics against SARS-CoV-2 infection.展开更多
Porosity is a challenging issue in additive manufacturing and is detrimental to the quality of the additively manufactured products.In this study,a real-time porosity reduction technique was developed by incorporating...Porosity is a challenging issue in additive manufacturing and is detrimental to the quality of the additively manufactured products.In this study,a real-time porosity reduction technique was developed by incorporating a pulse laser into a laser metal powder directed energy deposition(DED)system.The incorporated pulse laser can accelerate fluid flow within the melt pool and facilitate the escape of pores before complete solidification.It achieves this real-time porosity reduction by inducing accelerated and turbulent Marangoni flow,ultrasonic waves,and shock waves into the melt pool.The uniqueness and advantages of the proposed technique include the following:(1)For a laser metal powder DED process,this study proposed a noncontact,nondestructive,and real-time porosity reduction technique at the melt pool level.(2)It was experimentally and numerically validated that the developed technique did not alter the geometry and the grain structure of the manufactured Ti-6Al-4V samples.(3)Because the porosity reduction is accomplished at the melt pool level,its application is not limited by the size,shape,or complexity of the printing target.(4)The developed technique can be readily incorporated into the existing DED systems without any modification of the original tool-path design.The experimental results showed that the pore volume fraction decreased from 0.132%to 0.005%,no pores larger than 6×10^(4)μm^(3) were observed,and a 91%reduction in the total pore number was achieved when the pulse laser energy reached 11.5 mJ.展开更多
Aimed at the problem that the traditional suppressed fuzzy C-means clustering algorithms ignore the real needs of different objects, applying the same suppressed parameter for modifying membership degrees of all the o...Aimed at the problem that the traditional suppressed fuzzy C-means clustering algorithms ignore the real needs of different objects, applying the same suppressed parameter for modifying membership degrees of all the objects, a novel partition region-based suppressed fuzzy C-means clustering algorithm with better capacity of adaptability and robustness is proposed in this paper. The model based on the real needs of different objects is built, making it clear to decide whether to proceed with further determination; in addition, the external user-defined suppressed parameter is automatically selected according to the intrinsic structural characteristic of each dataset, making the proposed method become robust to the fluctuations in the incoming dataset and initial conditions. Experimental results show that the proposed method is more robust than its counterparts and overcomes the weakness of the original suppressed clustering algorithm in most cases.展开更多
Four new cyclohexapeptides,pyridapeptides F–I(1–4),were isolated from the fermentation broth of marine sponge-derived Streptomyces sp.OUCMDZ-4539.The pyridapeptides F–H(1–3)are composed ofβ-hydroxyleucine,alanine...Four new cyclohexapeptides,pyridapeptides F–I(1–4),were isolated from the fermentation broth of marine sponge-derived Streptomyces sp.OUCMDZ-4539.The pyridapeptides F–H(1–3)are composed ofβ-hydroxyleucine,alanine,O-methylthreonine,hexahydropyridazine-3-carboxylic acid,5-hydroxytetrahydropyridazine-3-carboxylic acid,and(2S,3R,4E,6E)-2-amino-3–hydroxy-4,6-dienoic acid residues.Pyridapeptide I(4)contains(2S,3R,4E,6E)-2-amino-3–hydroxy-8-methylnona-4,6-dienoic acid residue and a very rare glycose residue,aculose.Their structures were determined based on spectroscopic analysis and chemical methods.Pyridapeptides G–I(2–4)have the 2,3,6-trideoxyhexose units glycosylated at theγ-OH-TPDA residue,displayed significant antiproliferative activity against four(PC9,MKN45,Hep G2,K562)or two(PC9,MKN45)human cancer cell lines.展开更多
Emerging and re-emerging viruses from wild animals have seriously threatened the health of humans and domesticated animals in recent years.Herein,we isolated a new mammalian orthoreovirus(MRV),Pika/MRV/GCCDC7/2019(PMR...Emerging and re-emerging viruses from wild animals have seriously threatened the health of humans and domesticated animals in recent years.Herein,we isolated a new mammalian orthoreovirus(MRV),Pika/MRV/GCCDC7/2019(PMRV-GCCDC7),in the Qinghai-Tibet Plateau wild pika(Ochotona curzoniae).Though the PMRVGCCDC7 shows features of a typical reovirus with ten gene segments arranged in 3:3:4 in length,the virus belongs to an independent evolutionary branch compared to other MRVs based on phylogenetic tree analysis.The results of cellular susceptibility,species tropism,and replication kinetics of PMRV-GCCDC7 indicated the virus could infect four human cell lines(A549,Huh7,HCT,and LoVo)and six non-human cell lines,including Vero-E6,LLCMK2,BHK-21,N2a,MDCK,and RfKT cell,derived from diverse mammals,i.e.monkey,mice,canine and bat,which revealed the potential of PMRV-GCCDC7 to infect a variety of hosts.Infection of BALB/c mice with PMRVGCCDC7 via intranasal inoculation led to relative weight loss,lung tissue damage and inflammation with the increase of virus titer,but no serious respiratory symptoms and death occurred.The characterization of the new reovirus from a plateau-based wild animal has expanded our knowledge of the host range of MRV and provided insight into its risk of trans-species transmission and zoonotic diseases.展开更多
In strong-field double ionization,two electrons are ionized by intense laser field.These two electrons move in the laser field and the state is described by a Coulomb-Volkov state,where the repulsive Coulomb state des...In strong-field double ionization,two electrons are ionized by intense laser field.These two electrons move in the laser field and the state is described by a Coulomb-Volkov state,where the repulsive Coulomb state describes the relative motion of the two electrons and the Volkov state describes the center-of-mass motion of the two electrons in the laser field.In the frame of scattering theory,we derive a simple analytical formula of the double ionization of He-like atoms.The effect of the Coulomb force between two electrons on the double ionization process is discussed.Numerical studies disclose that the Coulomb force enhances the ionization rate of high-energy electrons but suppresses the ionization rate of the lowest-energy electrons.展开更多
Methylation of cytosine is a conserved epigenetic modification that maintains the dynamic balance of methylation in plants under the regulation of methyltransferases and demethylases.In recent years,the study of DNA m...Methylation of cytosine is a conserved epigenetic modification that maintains the dynamic balance of methylation in plants under the regulation of methyltransferases and demethylases.In recent years,the study of DNA methylation in regulating the growth and development of plants and animals has become a key area of research.This review describes the regulatory mechanisms of DNA cytosine methylation in plants.It summarizes studies on epigenetic modifications of DNA methylation in fruit ripening,development,senescence,plant height,organ size,and under biotic and abiotic stresses in horticultural crops.The review provides a theoretical basis for understanding the mechanisms of DNA methylation and their relevance to breeding,genetic improvement,research,innovation,and exploitation of new cultivars of horticultural crops.展开更多
The conventional methodology for designing QC-LDPC decoders is applied for fixed configurations used in wireless communication standards, and the supported largest expansion factor Z (the parallelism of the layered de...The conventional methodology for designing QC-LDPC decoders is applied for fixed configurations used in wireless communication standards, and the supported largest expansion factor Z (the parallelism of the layered decoding) is a fixed number. In this paper, we study the circular-shifting network for decoding LDPC codes with arbitrary Z factor, especially for decoding large Z (Z P) codes, where P is the decoder parallelism. By buffering the P-length slices from the memory, and assembling the shifted slices in a fixed routine, the P-parallelism shift network can process Z-parallelism circular-shifting tasks. The implementation results show that the proposed network for arbitrary sized data shifting consumes only one times of additional resource cost compared to the traditional solution for only maximum P sized data shifting, and achieves significant saving on area and routing complexity.展开更多
In order to improve the electrical and frequency characteristics of SiGe heterojunction bipolar transistors (HBTs), a novel structure of SOI SiGe heterojunction bipolar transistor is designed in this work. Compared wi...In order to improve the electrical and frequency characteristics of SiGe heterojunction bipolar transistors (HBTs), a novel structure of SOI SiGe heterojunction bipolar transistor is designed in this work. Compared with traditional SOI SiGe HBT, the proposed device structure has smaller window widths of emitter and collector areas. Under the act of additional uniaxial stress induced by Si0.85Ge0.15, all the collector region, base region and emitter region are strained, which is beneficial to improve the performance of SiGe HBTs. Employing the SILVACOⓇTCAD tools, the numerical simulation results show that the maximum current gain βmax, the Earley voltage VA are achieved for 1062 and 186 V, respectively, the product of β and VA, i.e., β ×VA, is 1.975 × 105 V and, the peak cutoff frequency fT is 419 GHz when the Ge component in the base has configured to be a trapezoidal distribution. The proposed SOI SiGe HBT architecture has a 52.9% improvement in cutoff frequency fT compared to the conventional SOI SiGe HBTs.展开更多
The research on the tire industry cluster based on life cycle theory can be carried out by a four stage periods,namely initial period,growth period,maturity period,and recession period.This paper analyzes on the possi...The research on the tire industry cluster based on life cycle theory can be carried out by a four stage periods,namely initial period,growth period,maturity period,and recession period.This paper analyzes on the possible risks taken in each life cycle period as well as proposes corresponding suggestions to strengthen the research by looking into the conditions and factors of the continuous sustainable development process in a tire industry.展开更多
Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is continuously evolving since 2019.Some monoclonal antibodies(mAbs)have been developed and widely used,such as etesevimab(CB6)developed by Eli-Lilly/Junshi.H...Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is continuously evolving since 2019.Some monoclonal antibodies(mAbs)have been developed and widely used,such as etesevimab(CB6)developed by Eli-Lilly/Junshi.However,the mAb escaped from the variant of concern(VOC)ever since the emergence of Beta VOC,with a complete loss of efficacy against the Omicron subvariants.Here,we developed a broad-spectrum and affinity-mature antibody design(BAADesign)procedure to design CB6,enabling it to bind to the receptor-binding domains(RBDs)of multiple important Omicron subvariants,including the recent variant KP.2.Structural analysis confirmed the desired CB6-RBD interactions.Additionally,identical mutations in the complementarity determining regions(CDR)1 and CDR2 of the CB6 mutants also restored neutralizing potency for some RBD-1 group antibodies.Overall,the enhanced CB6 neutralizing capacity makes it a promising candidate against SARS-CoV-2 infection,and the BAADesign method has implications for the design of other antibodies.展开更多
Phenazine derivatives,a class of naturally occurring antibiotics primarily produced by bacteria,are regarded as promising scaffolds for developing new antibiotics.In this study,eight new dimeric phenazine derivatives,...Phenazine derivatives,a class of naturally occurring antibiotics primarily produced by bacteria,are regarded as promising scaffolds for developing new antibiotics.In this study,eight new dimeric phenazine derivatives,phenazostains K‒R(1‒8),along with two reported dimeric analogues,phenazostains B(9)and C(10),were isolated from the fermentation broth of the marine-derived Streptomyces sp.OUCMDZ-4923.Their structures were elucidated through spectroscopic analysis,primarily using NMR and HRESIMS spectra,ECD calculations,and the modified Mosher’s method.Compounds 1‒10 feature the 12-deoxysaphenate unit linked to various sites on methyl saphenate,phenazine,or methyl phenazine-1-carboxylate.Notably,compounds 1 and 2 represent the first dimeric phenazines linked by a 12,12'-oxy bridge.Our experimental results suggest that these dimers could be formed from methyl saphenate(12)through a nonenzymatic pathway.Moreover,the analysis of gene roles within their biosynthetic gene cluster revealed that phenazostains 1‒8 are formed through a nonenzymatic pro-cess.Additionally,all dimers were evaluated for their antibacterial activity;compounds 1,3‒5,and 9 exhibited inhibitory activities against both Staphylococcus aureus and its methicillin-resistant strain(MRSA),with MIC values ranging from 1.56 to 25.0μg/mL.展开更多
Double carbohelicenes have attracted considerable attention due to their aesthetic structures,distinctπ-conjugation extension,inherent chirality,and intriguing optical and electronic properties.Herein,the concise de ...Double carbohelicenes have attracted considerable attention due to their aesthetic structures,distinctπ-conjugation extension,inherent chirality,and intriguing optical and electronic properties.Herein,the concise de novo synthesis of a new double[5]carbohelicene 1 together with its chiroptical properties,isomerization process and lasing application is presented.1 was synthesized by a simple protocol involving the formation of a 6,6′-bipentacene as the key intermediate.It is worth noting that1 existed as two diastereomers 1-PP/MM and 1-PM,which were successfully isolated and unambiguously confirmed by Xray crystallography.The optical resolution of the racemic 1-PP/MM was successfully achieved by chiral-phase highperformance liquid chromatography(HPLC),and 1-PP and 1-MM were characterized by circular dichroism.Interestingly,it was found that 1-PP/MM could be completely isomerized to 1-PM upon heating,and the detailed thermodynamics and kinetics of the isomerization process were systematically investigated.1-PM exhibited deep-red luminescence with emission maximum at 723 nm and fluorescence quantum yield as high as 32.95%.Consequently,we can showcase the lasing application of 1-PM by doping with epoxy resin to assemble a bottle microlaser spontaneously,which the lasing wavelength is 796.6 nm at a threshold of 0.8 m J cm^(-2).We believe that our studies,including the facile synthesis methodology,detailed isomerization studies,and lasing application,will shed some light on the design and synthesis of novel carbohelical systems with more functions.展开更多
In the organisms with XX/XY sex chromosomes,Y chromosome is unique to males and plays an important role in male reproductive development.The study of Y chromosome genes will contribute to the development of pest genet...In the organisms with XX/XY sex chromosomes,Y chromosome is unique to males and plays an important role in male reproductive development.The study of Y chromosome genes will contribute to the development of pest genetic prevention and control technology.In this study,we identified 9 Y chromosome genes in Zeugodacus tau(Diptera:Tephritidae),including gene 16222.Protein structure analysis showed that 16222 was highly similar to odorant binding protein,and thus gene 16222 was named obp-Y.Obp-Y knockout(KO)significantly reduced hatching rate of offspring.Sperm detection results showed that obp-Y KO did not affect sperm number in the testes or sperm transfer during mating.We further examined the storage of sperms in females,and found that sperms in females mating with wild-type males began to transfer from spermathecal ducts to the spermathecae at hour 0 after the end of mating(AEM),and at 0-24 h AEM,the sperm count in the spermathecae gradually increased.However,no sperms were observed in spermathecae of females mating with mutant males at hours 0,4,8,24 and 48 AEM.In summary,this study revealed that Y chromosome gene obp-Y was necessary for the storage of sperms in females.Our findings not only provide theoretical basis for elucidating the function of the Y chromosome,but also offer a molecular target for the genetic control over Z.tau.展开更多
PD-L1 is a member of the B7 protein family,most of whose members so far were identified as dimers in a solution and crystalline state,either complexed or uncomplexed with their ligand(s).The binding of PD-L1 with its ...PD-L1 is a member of the B7 protein family,most of whose members so far were identified as dimers in a solution and crystalline state,either complexed or uncomplexed with their ligand(s).The binding of PD-L1 with its receptor PD-1(CD279)delivers an inhibitory signal regulating the T cell function.Simultaneously with the Garboczi group,we successfully solved another structure of human PD-L1(hPD-L1).Our protein crystallized in the space group of C222_(1) with two hPD-L1 molecules per asymmetric unit.After comparison of reported B7 structures,we have found some intrinsic factors involved in the interaction of these two molecules.Based on these results,we tend to believe this uncomplexed hPD-L1 structure demonstrated its potential dimeric state in solution,althougt it could just be an evolutionary relic,too weak to be detected under present technology,or still a functional unit deserved our attentions.展开更多
Coronavirus disease 2019(COVID-19)pandemic has spread in 220 countries/regions towreak havoc to human beings around theworld.At present,the second wave of COVID-19 has begun in many European countries.The complete con...Coronavirus disease 2019(COVID-19)pandemic has spread in 220 countries/regions towreak havoc to human beings around theworld.At present,the second wave of COVID-19 has begun in many European countries.The complete control of COVID-19 is very urgent.Although China quickly brought the virus under control,there have been eight sporadic outbreaks in China since then.Both in Xinfadi of Beijing and Dalian outbreak of COVID-19,environmental swab samples related to imported cold chain food were tested nucleic acid positive for SARS-CoV-2.In this outbreak in Qingdao,we directly isolated SARS-CoV-2 from the cod outer package's surface swab samples.This is the first time worldwide,SARS-CoV-2 were isolated from the imported frozen cod outer package's surface,which showed that imported frozen food industry could import SARS-CoV-2 virus.展开更多
From the oligotrophic culture of a soft coral-associated actinomycetes strain, Streptomyces sp. OUCMDZ-1703, we isolated and identified two new chlorinated polyketides that we named strepchloritides A and B （1 and 2...From the oligotrophic culture of a soft coral-associated actinomycetes strain, Streptomyces sp. OUCMDZ-1703, we isolated and identified two new chlorinated polyketides that we named strepchloritides A and B （1 and 2）, three thiazole derivatives known as watasemycin A （3）, pulicatin G （4） and aerugine （5）, along with pyrrole- 2-carboxamide, furan-2-carboxamide and 1-（3,5-dihydroxyphenyl）ethanone. The new structures of 1 and 2 were determined by spectroscopic studies such as 1D- and 2D-NMR and MS analyses, while the known compounds were identified by comparison of the NMR data with those in literatures. The results showed that actinomycete strain OUCMDZ-1703 could use the relative high ratio of chlorine in the oligotrophic medium to synthesize chlorinated natural products. New compounds 1 and 2 displayed cytotoxicity against the MCF-7 ceils with ICs0 values of 9.9 and 20.2 ~tmoloL-1, respectively. Thiazole derivatives 3 and 5 were first found to be active against three clinical strains of methicillin-resistant Staphylococcus aureus （MRSA082, MRSA111 and MRSA234） with the same MIC/MBC values of 7.81/7.81 μg·mL-1.展开更多
Social engineering has posed a serious threat to cyberspace security.To protect against social engineering attacks,a fundamental work is to know what constitutes social engineering.This paper first develops a domain o...Social engineering has posed a serious threat to cyberspace security.To protect against social engineering attacks,a fundamental work is to know what constitutes social engineering.This paper first develops a domain ontology of social engineering in cybersecurity and conducts ontology evaluation by its knowledge graph application.The domain ontology defines 11 concepts of core entities that significantly constitute or affect social engineering domain,together with 22 kinds of relations describing how these entities related to each other.It provides a formal and explicit knowledge schema to understand,analyze,reuse and share domain knowledge of social engineering.Furthermore,this paper builds a knowledge graph based on 15 social engineering attack incidents and scenarios.7 knowledge graph application examples(in 6 analysis patterns)demonstrate that the ontology together with knowledge graph is useful to 1)understand and analyze social engineering attack scenario and incident,2)find the top ranked social engineering threat elements(e.g.the most exploited human vulnerabilities and most used attack mediums),3)find potential social engineering threats to victims,4)find potential targets for social engineering attackers,5)find potential attack paths from specific attacker to specific target,and 6)analyze the same origin attacks.展开更多
基金Project supported by the National Key Research and Development Program of China(2022YFB3504100,2021YFB3500600)Chunhui Project Foundation of the Education Department of China(202200554)。
文摘The rapid development of rare earth metal elements in the field of photocatalysis is due to their excellent optical and physicochemical properties.Benefiting from the unique external electronic structure of 4f_15d_16S_2,superior electronegativity of the 4f orbitals,and strong oxygen storage-release ability in Ce^(4+)/Ce^(3+)reversible pairs,cerium dioxide(CeO_(2))has attracted increasing interest from scientists.Nevertheless,the fast recombination of photoinduced electron-hole pairs and wide energy band gap of bare CeO_(2)significantly limit its practical applications.To overcome the above drawbacks,the construction of heterojunctions has been developed to broaden the absorption spectrum and accelerate the charge transfer.This review presents a mini-review of the synthesis of CeO_(2)-based heterojunctions including typeⅡ,Z-scheme,and S-scheme photocatalysts,as well as the corresponding applications in photocatalytic bactericidal and antitumor therapy.Finally,the latest advancements and potential perspectives on their future development are also discussed.
基金This work was supported by the National Research and Development Project of China(Grant No.2020YFC0841100)Fundamental Research Funds for CAMS of China(Grant No.2020HY320001)+3 种基金National Key Research and Development Project of China(Grant No.2016YFD0500304)CAMS initiative for Innovative Medicine of China(Grant No.2016-I2M-2-006)National Mega projects of China for Major Infectious Diseases(Grant No.2017ZX10304402)and National Key Research and Development Programme of China(2016YFD0500301,2020YFC0840800,2020YFC0840900).
文摘Background:Since December 2019,an outbreak of the Corona Virus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus(SARS-CoV-2)in Wuhan,China,has become a public health emergency of international concern.The high fatality of aged cases caused by SARS-CoV-2 was a need to explore the possible age-related phenomena with non-human primate models.Methods:Three 3-5 years old and two 15 years old rhesus macaques were intratracheally infected with SARS-CoV-2,and then analyzed by clinical signs,viral replication,chest X-ray,histopathological changes and immune response.Results:Viral replication of nasopharyngeal swabs,anal swabs and lung in old monkeys was more active than that in young monkeys for 14 days after SARS-CoV-2 challenge.Monkeys developed typical interstitial pneumonia characterized by thickened alveolar septum accompanied with inflammation and edema,notably,old monkeys exhibited diffuse severe interstitial pneumonia.Viral antigens were detected mainly in alveolar epithelial cells and macrophages.Conclusion:SARS-CoV-2 caused more severe interstitial pneumonia in old monkeys than that in young monkeys.Rhesus macaque models infected with SARS-CoV-2 provided insight into the pathogenic mechanism and facilitated the development of vaccines and therapeutics against SARS-CoV-2 infection.
基金supported by a National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)[Grant No.2019R1A3B3067987]supported by SQ Engineering during his stay at KAIST。
文摘Porosity is a challenging issue in additive manufacturing and is detrimental to the quality of the additively manufactured products.In this study,a real-time porosity reduction technique was developed by incorporating a pulse laser into a laser metal powder directed energy deposition(DED)system.The incorporated pulse laser can accelerate fluid flow within the melt pool and facilitate the escape of pores before complete solidification.It achieves this real-time porosity reduction by inducing accelerated and turbulent Marangoni flow,ultrasonic waves,and shock waves into the melt pool.The uniqueness and advantages of the proposed technique include the following:(1)For a laser metal powder DED process,this study proposed a noncontact,nondestructive,and real-time porosity reduction technique at the melt pool level.(2)It was experimentally and numerically validated that the developed technique did not alter the geometry and the grain structure of the manufactured Ti-6Al-4V samples.(3)Because the porosity reduction is accomplished at the melt pool level,its application is not limited by the size,shape,or complexity of the printing target.(4)The developed technique can be readily incorporated into the existing DED systems without any modification of the original tool-path design.The experimental results showed that the pore volume fraction decreased from 0.132%to 0.005%,no pores larger than 6×10^(4)μm^(3) were observed,and a 91%reduction in the total pore number was achieved when the pulse laser energy reached 11.5 mJ.
基金supported by the National Natural Science Foundation of China(61401363)the Science and Technology on Avionics Integration Laboratory and Aeronautical Science Foundation(20155153034)+1 种基金the Fundamental Research Funds for the Central Universities(3102016AXXX0053102015BJJGZ009)
文摘Aimed at the problem that the traditional suppressed fuzzy C-means clustering algorithms ignore the real needs of different objects, applying the same suppressed parameter for modifying membership degrees of all the objects, a novel partition region-based suppressed fuzzy C-means clustering algorithm with better capacity of adaptability and robustness is proposed in this paper. The model based on the real needs of different objects is built, making it clear to decide whether to proceed with further determination; in addition, the external user-defined suppressed parameter is automatically selected according to the intrinsic structural characteristic of each dataset, making the proposed method become robust to the fluctuations in the incoming dataset and initial conditions. Experimental results show that the proposed method is more robust than its counterparts and overcomes the weakness of the original suppressed clustering algorithm in most cases.
基金financially supported by the National Natural Science Foundation of China(No.U1906213)the National Key Research and Development Program of China(No.2022YFC2804100)。
文摘Four new cyclohexapeptides,pyridapeptides F–I(1–4),were isolated from the fermentation broth of marine sponge-derived Streptomyces sp.OUCMDZ-4539.The pyridapeptides F–H(1–3)are composed ofβ-hydroxyleucine,alanine,O-methylthreonine,hexahydropyridazine-3-carboxylic acid,5-hydroxytetrahydropyridazine-3-carboxylic acid,and(2S,3R,4E,6E)-2-amino-3–hydroxy-4,6-dienoic acid residues.Pyridapeptide I(4)contains(2S,3R,4E,6E)-2-amino-3–hydroxy-8-methylnona-4,6-dienoic acid residue and a very rare glycose residue,aculose.Their structures were determined based on spectroscopic analysis and chemical methods.Pyridapeptides G–I(2–4)have the 2,3,6-trideoxyhexose units glycosylated at theγ-OH-TPDA residue,displayed significant antiproliferative activity against four(PC9,MKN45,Hep G2,K562)or two(PC9,MKN45)human cancer cell lines.
基金the National Key Research and Development Program of China(2021YFC0863400,2022YFC2604105).
文摘Emerging and re-emerging viruses from wild animals have seriously threatened the health of humans and domesticated animals in recent years.Herein,we isolated a new mammalian orthoreovirus(MRV),Pika/MRV/GCCDC7/2019(PMRV-GCCDC7),in the Qinghai-Tibet Plateau wild pika(Ochotona curzoniae).Though the PMRVGCCDC7 shows features of a typical reovirus with ten gene segments arranged in 3:3:4 in length,the virus belongs to an independent evolutionary branch compared to other MRVs based on phylogenetic tree analysis.The results of cellular susceptibility,species tropism,and replication kinetics of PMRV-GCCDC7 indicated the virus could infect four human cell lines(A549,Huh7,HCT,and LoVo)and six non-human cell lines,including Vero-E6,LLCMK2,BHK-21,N2a,MDCK,and RfKT cell,derived from diverse mammals,i.e.monkey,mice,canine and bat,which revealed the potential of PMRV-GCCDC7 to infect a variety of hosts.Infection of BALB/c mice with PMRVGCCDC7 via intranasal inoculation led to relative weight loss,lung tissue damage and inflammation with the increase of virus titer,but no serious respiratory symptoms and death occurred.The characterization of the new reovirus from a plateau-based wild animal has expanded our knowledge of the host range of MRV and provided insight into its risk of trans-species transmission and zoonotic diseases.
基金the National Natural Science Foundation of China(Grant Nos.11674231 and 12074261)the Shanghai Natural Science Foundation,China(Grant No.20ZR1441600).
文摘In strong-field double ionization,two electrons are ionized by intense laser field.These two electrons move in the laser field and the state is described by a Coulomb-Volkov state,where the repulsive Coulomb state describes the relative motion of the two electrons and the Volkov state describes the center-of-mass motion of the two electrons in the laser field.In the frame of scattering theory,we derive a simple analytical formula of the double ionization of He-like atoms.The effect of the Coulomb force between two electrons on the double ionization process is discussed.Numerical studies disclose that the Coulomb force enhances the ionization rate of high-energy electrons but suppresses the ionization rate of the lowest-energy electrons.
基金This work was supported by the National Natural Science Foundation of China(32270367)the Office of Education of Anhui Province for Distinguished Young Scholars(2022AH020061)the National Key Research and Development Program of China(2021YFA1300401 and NK2022010301).
文摘Methylation of cytosine is a conserved epigenetic modification that maintains the dynamic balance of methylation in plants under the regulation of methyltransferases and demethylases.In recent years,the study of DNA methylation in regulating the growth and development of plants and animals has become a key area of research.This review describes the regulatory mechanisms of DNA cytosine methylation in plants.It summarizes studies on epigenetic modifications of DNA methylation in fruit ripening,development,senescence,plant height,organ size,and under biotic and abiotic stresses in horticultural crops.The review provides a theoretical basis for understanding the mechanisms of DNA methylation and their relevance to breeding,genetic improvement,research,innovation,and exploitation of new cultivars of horticultural crops.
文摘The conventional methodology for designing QC-LDPC decoders is applied for fixed configurations used in wireless communication standards, and the supported largest expansion factor Z (the parallelism of the layered decoding) is a fixed number. In this paper, we study the circular-shifting network for decoding LDPC codes with arbitrary Z factor, especially for decoding large Z (Z P) codes, where P is the decoder parallelism. By buffering the P-length slices from the memory, and assembling the shifted slices in a fixed routine, the P-parallelism shift network can process Z-parallelism circular-shifting tasks. The implementation results show that the proposed network for arbitrary sized data shifting consumes only one times of additional resource cost compared to the traditional solution for only maximum P sized data shifting, and achieves significant saving on area and routing complexity.
文摘In order to improve the electrical and frequency characteristics of SiGe heterojunction bipolar transistors (HBTs), a novel structure of SOI SiGe heterojunction bipolar transistor is designed in this work. Compared with traditional SOI SiGe HBT, the proposed device structure has smaller window widths of emitter and collector areas. Under the act of additional uniaxial stress induced by Si0.85Ge0.15, all the collector region, base region and emitter region are strained, which is beneficial to improve the performance of SiGe HBTs. Employing the SILVACOⓇTCAD tools, the numerical simulation results show that the maximum current gain βmax, the Earley voltage VA are achieved for 1062 and 186 V, respectively, the product of β and VA, i.e., β ×VA, is 1.975 × 105 V and, the peak cutoff frequency fT is 419 GHz when the Ge component in the base has configured to be a trapezoidal distribution. The proposed SOI SiGe HBT architecture has a 52.9% improvement in cutoff frequency fT compared to the conventional SOI SiGe HBTs.
文摘The research on the tire industry cluster based on life cycle theory can be carried out by a four stage periods,namely initial period,growth period,maturity period,and recession period.This paper analyzes on the possible risks taken in each life cycle period as well as proposes corresponding suggestions to strengthen the research by looking into the conditions and factors of the continuous sustainable development process in a tire industry.
基金supported by the National Natural Science Foundation of China(82225021)the National Key R&D Program of China(2022YFC2303403,2021YFA1300803,2021YFA1301404).
文摘Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is continuously evolving since 2019.Some monoclonal antibodies(mAbs)have been developed and widely used,such as etesevimab(CB6)developed by Eli-Lilly/Junshi.However,the mAb escaped from the variant of concern(VOC)ever since the emergence of Beta VOC,with a complete loss of efficacy against the Omicron subvariants.Here,we developed a broad-spectrum and affinity-mature antibody design(BAADesign)procedure to design CB6,enabling it to bind to the receptor-binding domains(RBDs)of multiple important Omicron subvariants,including the recent variant KP.2.Structural analysis confirmed the desired CB6-RBD interactions.Additionally,identical mutations in the complementarity determining regions(CDR)1 and CDR2 of the CB6 mutants also restored neutralizing potency for some RBD-1 group antibodies.Overall,the enhanced CB6 neutralizing capacity makes it a promising candidate against SARS-CoV-2 infection,and the BAADesign method has implications for the design of other antibodies.
基金supported by the National Key Research and Development Program of China(No.2022YFC2804100)the National Natural Science Foundation of China(No.82473838)Guizhou Provincial Basic Research Program(Natural Science)(No.QKHJC MS[2025]117).
文摘Phenazine derivatives,a class of naturally occurring antibiotics primarily produced by bacteria,are regarded as promising scaffolds for developing new antibiotics.In this study,eight new dimeric phenazine derivatives,phenazostains K‒R(1‒8),along with two reported dimeric analogues,phenazostains B(9)and C(10),were isolated from the fermentation broth of the marine-derived Streptomyces sp.OUCMDZ-4923.Their structures were elucidated through spectroscopic analysis,primarily using NMR and HRESIMS spectra,ECD calculations,and the modified Mosher’s method.Compounds 1‒10 feature the 12-deoxysaphenate unit linked to various sites on methyl saphenate,phenazine,or methyl phenazine-1-carboxylate.Notably,compounds 1 and 2 represent the first dimeric phenazines linked by a 12,12'-oxy bridge.Our experimental results suggest that these dimers could be formed from methyl saphenate(12)through a nonenzymatic pathway.Moreover,the analysis of gene roles within their biosynthetic gene cluster revealed that phenazostains 1‒8 are formed through a nonenzymatic pro-cess.Additionally,all dimers were evaluated for their antibacterial activity;compounds 1,3‒5,and 9 exhibited inhibitory activities against both Staphylococcus aureus and its methicillin-resistant strain(MRSA),with MIC values ranging from 1.56 to 25.0μg/mL.
基金supported by the National Natural Science Foundation of China(22071061)the Shanghai Natural Science Foundation(22ZR1420600)the Fundamental Research Funds for the Central Universities。
文摘Double carbohelicenes have attracted considerable attention due to their aesthetic structures,distinctπ-conjugation extension,inherent chirality,and intriguing optical and electronic properties.Herein,the concise de novo synthesis of a new double[5]carbohelicene 1 together with its chiroptical properties,isomerization process and lasing application is presented.1 was synthesized by a simple protocol involving the formation of a 6,6′-bipentacene as the key intermediate.It is worth noting that1 existed as two diastereomers 1-PP/MM and 1-PM,which were successfully isolated and unambiguously confirmed by Xray crystallography.The optical resolution of the racemic 1-PP/MM was successfully achieved by chiral-phase highperformance liquid chromatography(HPLC),and 1-PP and 1-MM were characterized by circular dichroism.Interestingly,it was found that 1-PP/MM could be completely isomerized to 1-PM upon heating,and the detailed thermodynamics and kinetics of the isomerization process were systematically investigated.1-PM exhibited deep-red luminescence with emission maximum at 723 nm and fluorescence quantum yield as high as 32.95%.Consequently,we can showcase the lasing application of 1-PM by doping with epoxy resin to assemble a bottle microlaser spontaneously,which the lasing wavelength is 796.6 nm at a threshold of 0.8 m J cm^(-2).We believe that our studies,including the facile synthesis methodology,detailed isomerization studies,and lasing application,will shed some light on the design and synthesis of novel carbohelical systems with more functions.
基金supported by National Key R&D Program of China(No.2021YFC2600400)China Agriculture Research System of MOF and MARA(CARS-26)Hubei Hongshan Laboratory.
文摘In the organisms with XX/XY sex chromosomes,Y chromosome is unique to males and plays an important role in male reproductive development.The study of Y chromosome genes will contribute to the development of pest genetic prevention and control technology.In this study,we identified 9 Y chromosome genes in Zeugodacus tau(Diptera:Tephritidae),including gene 16222.Protein structure analysis showed that 16222 was highly similar to odorant binding protein,and thus gene 16222 was named obp-Y.Obp-Y knockout(KO)significantly reduced hatching rate of offspring.Sperm detection results showed that obp-Y KO did not affect sperm number in the testes or sperm transfer during mating.We further examined the storage of sperms in females,and found that sperms in females mating with wild-type males began to transfer from spermathecal ducts to the spermathecae at hour 0 after the end of mating(AEM),and at 0-24 h AEM,the sperm count in the spermathecae gradually increased.However,no sperms were observed in spermathecae of females mating with mutant males at hours 0,4,8,24 and 48 AEM.In summary,this study revealed that Y chromosome gene obp-Y was necessary for the storage of sperms in females.Our findings not only provide theoretical basis for elucidating the function of the Y chromosome,but also offer a molecular target for the genetic control over Z.tau.
基金This work was supported by a grant from Ministry of Science and Technology(MOST)of China for the basic research program 973,Grant No.2006CB504204a grant from National Natural Science Foundation(NSFC)of China,Grant No.30671903+3 种基金a grant from Chinese Academy of Sciences(CAS)Knowledge Innovation Project,Grant No.KSCX2-SW-227G.F.G.is a distinguished young investigator of the NSFC(Grant No.30525010)Y.C.is a Ph.D.student supported by Science Innovation Project,Graduate University of Chinese Academy of Sciences(GUCAS),No.0729031EE1The China-Japan Joint Laboratory of Molecular Immunology and Molecular Microbiology is partlially supported by Japan MEXT(Ministry of Education,Culture,Sports,Science and Technology).
文摘PD-L1 is a member of the B7 protein family,most of whose members so far were identified as dimers in a solution and crystalline state,either complexed or uncomplexed with their ligand(s).The binding of PD-L1 with its receptor PD-1(CD279)delivers an inhibitory signal regulating the T cell function.Simultaneously with the Garboczi group,we successfully solved another structure of human PD-L1(hPD-L1).Our protein crystallized in the space group of C222_(1) with two hPD-L1 molecules per asymmetric unit.After comparison of reported B7 structures,we have found some intrinsic factors involved in the interaction of these two molecules.Based on these results,we tend to believe this uncomplexed hPD-L1 structure demonstrated its potential dimeric state in solution,althougt it could just be an evolutionary relic,too weak to be detected under present technology,or still a functional unit deserved our attentions.
基金supported by the National Key Research and Develop-ment Project(2020YFC0846200,2020YFC0840800).
文摘Coronavirus disease 2019(COVID-19)pandemic has spread in 220 countries/regions towreak havoc to human beings around theworld.At present,the second wave of COVID-19 has begun in many European countries.The complete control of COVID-19 is very urgent.Although China quickly brought the virus under control,there have been eight sporadic outbreaks in China since then.Both in Xinfadi of Beijing and Dalian outbreak of COVID-19,environmental swab samples related to imported cold chain food were tested nucleic acid positive for SARS-CoV-2.In this outbreak in Qingdao,we directly isolated SARS-CoV-2 from the cod outer package's surface swab samples.This is the first time worldwide,SARS-CoV-2 were isolated from the imported frozen cod outer package's surface,which showed that imported frozen food industry could import SARS-CoV-2 virus.
文摘From the oligotrophic culture of a soft coral-associated actinomycetes strain, Streptomyces sp. OUCMDZ-1703, we isolated and identified two new chlorinated polyketides that we named strepchloritides A and B （1 and 2）, three thiazole derivatives known as watasemycin A （3）, pulicatin G （4） and aerugine （5）, along with pyrrole- 2-carboxamide, furan-2-carboxamide and 1-（3,5-dihydroxyphenyl）ethanone. The new structures of 1 and 2 were determined by spectroscopic studies such as 1D- and 2D-NMR and MS analyses, while the known compounds were identified by comparison of the NMR data with those in literatures. The results showed that actinomycete strain OUCMDZ-1703 could use the relative high ratio of chlorine in the oligotrophic medium to synthesize chlorinated natural products. New compounds 1 and 2 displayed cytotoxicity against the MCF-7 ceils with ICs0 values of 9.9 and 20.2 ~tmoloL-1, respectively. Thiazole derivatives 3 and 5 were first found to be active against three clinical strains of methicillin-resistant Staphylococcus aureus （MRSA082, MRSA111 and MRSA234） with the same MIC/MBC values of 7.81/7.81 μg·mL-1.
基金the National Key Research and Development Program of China(2017YFB0802804)the Joint Fund of the National Natural Science Foundation of China(U1766215).
文摘Social engineering has posed a serious threat to cyberspace security.To protect against social engineering attacks,a fundamental work is to know what constitutes social engineering.This paper first develops a domain ontology of social engineering in cybersecurity and conducts ontology evaluation by its knowledge graph application.The domain ontology defines 11 concepts of core entities that significantly constitute or affect social engineering domain,together with 22 kinds of relations describing how these entities related to each other.It provides a formal and explicit knowledge schema to understand,analyze,reuse and share domain knowledge of social engineering.Furthermore,this paper builds a knowledge graph based on 15 social engineering attack incidents and scenarios.7 knowledge graph application examples(in 6 analysis patterns)demonstrate that the ontology together with knowledge graph is useful to 1)understand and analyze social engineering attack scenario and incident,2)find the top ranked social engineering threat elements(e.g.the most exploited human vulnerabilities and most used attack mediums),3)find potential social engineering threats to victims,4)find potential targets for social engineering attackers,5)find potential attack paths from specific attacker to specific target,and 6)analyze the same origin attacks.
