We present a dynamic model of cavitation bubbles in a cluster,in which the effects of evaporation,condensation,and bubble-bubble interactions are taken into consideration.Under different ultrasound conditions,we exami...We present a dynamic model of cavitation bubbles in a cluster,in which the effects of evaporation,condensation,and bubble-bubble interactions are taken into consideration.Under different ultrasound conditions,we examine how the dynamics of cavitation bubbles are affected by several factors,such as the locations of the bubbles,the ambient radius,and the number of bubbles.Herein the variations of bubble radius,energy,temperature,pressure,and the quantity of vapor molecules are analyzed.Our findings reveal that bubble-bubble interactions can restrict the expansion of bubbles,reduce the exchange of energy among vapor molecules,and diminish the maximum internal temperature and pressure when bursting.The ambient radius of bubbles can influence the intensities of their oscillations,with clusters comprised of smaller bubbles creating optimal conditions for generating high-temperature and high-pressure regions.Moreover,an increase in the number of bubbles can further inhibit cavitation activities.The frequency,pressure and waveform of the driving wave can also exert a significant influence on cavitation activities,with rectangular waves enhancing and triangular waves weakening the cavitation of bubbles in the cluster.These results provide a theoretical basis for understanding the dynamics of cavitation bubbles in a bubble cluster,and the factors that affect their behaviors.展开更多
With the widespread use of Internet of Things(IoT)technology in daily life and the considerable safety risks of falls for elderly individuals,research on IoT-based fall detection systems has gainedmuch attention.This ...With the widespread use of Internet of Things(IoT)technology in daily life and the considerable safety risks of falls for elderly individuals,research on IoT-based fall detection systems has gainedmuch attention.This paper proposes an IoT-based spatiotemporal data processing framework based on a depthwise separable convolution generative adversarial network using skip-connection(Skip-DSCGAN)for fall detection.The method uses spatiotemporal data from accelerometers and gyroscopes in inertial sensors as input data.A semisupervised learning approach is adopted to train the model using only activities of daily living(ADL)data,which can avoid data imbalance problems.Furthermore,a quantile-based approach is employed to determine the fall threshold,which makes the fall detection frameworkmore robust.This proposed fall detection framework is evaluated against four other generative adversarial network(GAN)models with superior anomaly detection performance using two fall public datasets(SisFall&MobiAct).The test results show that the proposed method achieves better results,reaching 96.93% and 92.75% accuracy on the above two test datasets,respectively.At the same time,the proposed method also achieves satisfactory results in terms ofmodel size and inference delay time,making it suitable for deployment on wearable devices with limited resources.In addition,this paper also compares GAN-based semisupervised learning methods with supervised learning methods commonly used in fall detection.It clarifies the advantages of GAN-based semisupervised learning methods in fall detection.展开更多
In this paper, we investigate a blow-up phenomenon for a semilinear parabolic system on locally finite graphs. Under some appropriate assumptions on the curvature condition CDE’(n,0), the polynomial volume growth of ...In this paper, we investigate a blow-up phenomenon for a semilinear parabolic system on locally finite graphs. Under some appropriate assumptions on the curvature condition CDE’(n,0), the polynomial volume growth of degree m, the initial values, and the exponents in absorption terms, we prove that every non-negative solution of the semilinear parabolic system blows up in a finite time. Our current work extends the results achieved by Lin and Wu (Calc Var Partial Differ Equ, 2017, 56: Art 102) and Wu (Rev R Acad Cien Serie A Mat, 2021, 115: Art 133).展开更多
Quasi-bound state in the continuum(QBIC)resonance is gradually attracting attention and being applied in Goos-Hänchen(GH)shift enhancement due to its high quality(Q)factor and superior optical confinement.Current...Quasi-bound state in the continuum(QBIC)resonance is gradually attracting attention and being applied in Goos-Hänchen(GH)shift enhancement due to its high quality(Q)factor and superior optical confinement.Currently,symmetry-protected QBIC resonance is often achieved by breaking the geometric symmetry,but few cases are achieved by breaking the material symmetry.This paper proposes a dielectric compound grating to achieve a high Q factor and high-reflection symmetry-protectede QBIC resonance based on material asymmetry.Theoretical calculations show that the symmetry-protected QBIC resonance achieved by material asymmetry can significantly increase the GH shift up to-980 times the resonance wavelength,and the maximum GH shift is located at the reflection peak with unity reflectance.This paper provides a theoretical basis for designing and fabricating high-performance GH shift tunable metasurfaces/dielectric gratings in the future.展开更多
This work focuses on numerically studying hydrodynamic interaction between a passive particle and a self-propelled particle,termed a squirmer,by using a two-dimensional lattice Boltzmann method(LBM).It is found that t...This work focuses on numerically studying hydrodynamic interaction between a passive particle and a self-propelled particle,termed a squirmer,by using a two-dimensional lattice Boltzmann method(LBM).It is found that the squirmer can capture a passive particle and propel it simultaneously,provided the passive particle is situated within the squirmer's wake.Our research shows that the critical capture distance,which determines whether the particle is captured,primarily depends on the intensity of the squirmer's dipolarity.The stronger dipolarity of squirmer results in an increased critical capture distance.Conversely,the Reynolds number is found to have minimal influence on this interaction.Interestingly,the passive particle,when driven by the squirmer's wake,contributes to a reduction in the squirmer's drag.This results in a mutual acceleration for both particles.Our findings can provide valuable perspectives for formulating the principles of reducing the drag of micro-swimmers and help to achieve the goal of using micro-swimmers to transport goods without physical tethers.展开更多
This study introduces a pre-orthogonal adaptive Fourier decomposition(POAFD)to obtain approximations and numerical solutions to the fractional Laplacian initial value problem and the extension problem of Caffarelli an...This study introduces a pre-orthogonal adaptive Fourier decomposition(POAFD)to obtain approximations and numerical solutions to the fractional Laplacian initial value problem and the extension problem of Caffarelli and Silvestre(generalized Poisson equation).As a first step,the method expands the initial data function into a sparse series of the fundamental solutions with fast convergence,and,as a second step,makes use of the semigroup or the reproducing kernel property of each of the expanding entries.Experiments show the effectiveness and efficiency of the proposed series solutions.展开更多
This paper draws on the experience of the eighth plenary meeting of the ISO/TC 321, Transaction assurance in e-commerce, held in Hangzhou of China in November 2023, and explores potential ways in which developing coun...This paper draws on the experience of the eighth plenary meeting of the ISO/TC 321, Transaction assurance in e-commerce, held in Hangzhou of China in November 2023, and explores potential ways in which developing countries in Africa can drive their development and contribute to global industrial progress by leveraging ISO/TC 321 standards. It provides practical recommendations for utilizing e-commerce standardization and related standards to stimulate economic growth and enhance business practices.展开更多
Metal tellurides(MTes) are highly attractive as promising anodes for high-performance potassium-ion batteries. The capacity attenuation of most reported MTe anodes is attributed to their poor electrical conductivity a...Metal tellurides(MTes) are highly attractive as promising anodes for high-performance potassium-ion batteries. The capacity attenuation of most reported MTe anodes is attributed to their poor electrical conductivity and large volume variation. The evolution mechanisms, dissolution properties, and corresponding manipulation strategies of intermediates(K-polytellurides, K-pTe_(x)) are rarely mentioned. Herein,we propose a novel structural engineering strategy to confine ultrafine CoTe_(2) nanodots in hierarchical nanogrid-in-nanofiber carbon substrates(CoTe_(2)@NC@NSPCNFs) for smooth immobilization of K-pTe_(x) and highly reversible conversion of CoTe_(2) by manipulating the intense electrochemical reaction process. Various in situ/ex situ techniques and density functional theory calculations have been performed to clarify the formation, transformation, and dissolution of K-pTe_(x)(K_(5)Te_(3) and K_(2)Te), as well as verifying the robust physical barrier and the strong chemisorption of K_(5)Te_(3) and K_(2)Te on S, N co-doped dual-type carbon substrates. Additionally, the hierarchical nanogrid-in-nanofiber nanostructure increases the chemical anchoring sites for K-pTe_(x), provides sufficient volume buffer space, and constructs highly interconnected conductive microcircuits, further propelling the battery reaction to new heights(3500 cycles at 2.0 A g^(-1)). Furthermore, the full cells further demonstrate the potential for practical applications. This work provides new insights into manipulating K-pTe_(x) in the design of ultralong-cycling MTe anodes for advanced PIBs.展开更多
We investigate the anisotropic band structure and its evolution under tensile strains along different crystallographic directions in bulk black phosphorus(BP)using angle-resolved photoemission spectroscopy and density...We investigate the anisotropic band structure and its evolution under tensile strains along different crystallographic directions in bulk black phosphorus(BP)using angle-resolved photoemission spectroscopy and density functional theory.The results show that there are band crossings in the Z-L(armchair)direction.展开更多
Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential applications.In this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor t...Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential applications.In this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor transport method.We measured the magnetization,longitudinal resistivityρxx(T,H),Hall resistivityρxy(T,H),as well as performed calculations of the electronic band structure.It was found that V_(1/3)TaS_(2) is an A-type antiferromagnet with the Neel temperature T_(N)=6.20 K,and exhibits a negative magnetoresistance(MR)near T_(N).Both band structure calculations and Hall resistivity measurements demonstrated it is a magnetic semimetal.展开更多
Porcine circovirus type 2 (PCV2) is closely related to the postweaning multisystemic wasting syndrome (PMWS). In this study, the pig serum and tissue samples collected from different regions of Hangzhou District in Zh...Porcine circovirus type 2 (PCV2) is closely related to the postweaning multisystemic wasting syndrome (PMWS). In this study, the pig serum and tissue samples collected from different regions of Hangzhou District in Zhejiang Province of China between 2003 and 2005 were analyzed by enzyme-linked immunosorbent assay (ELISA) for PCV2 antibody and by polymerase chain reaction (PCR) for ORF2 gene. The results show that out of 1250 randomly collected serum samples, 500 sera (40%) were seropositive for PCV2. PCR results demonstrate that Hangzhou PCV2 with more than 50% Chinese PCV2 strains and French PCV2 formed Cluster A. Only one PCV2 from Hangzhou belonged to Cluster B with some other Chinese PCV2 and Netherlands’s isolates. Cluster C consisted of PCV2 isolates from China, US, Canada, UK and Germany. The results indicate that the PCV2 infection was widespread in Hangzhou.展开更多
With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others w...With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others without the protection of face masks,which greatly increases the risk of COVID-19 transmission.Therefore,the transmission mechanism of respiratory droplets in extremely crowded dining environments should be investigated.In this study,a numerical simulation of coughing at dining tables under two conditions was performed,namely the presence and absence of protective partitions,and the evaporation and condensation of aerosol droplets in the air were examined.By using the numerical method,we analyzed and verified the isolation effect of dining table partitions in the propagation of aerosol droplets.The effect of changes in room temperature on the diffusion of coughed aerosols when partitions were present was analyzed.We demonstrated how respiratory droplets spread through coughing and how these droplets affect others.Finally,we proposed a design for a dining table partition that minimizes the transmission of COVID-19.展开更多
Sapindus L.species are widely cultivated for biodiesel,biomedical,and biochemical raw materials in southern China.However,yields fuctuate widely due to the lack of high-yielding,high-quality,stable cultivars.Therefore...Sapindus L.species are widely cultivated for biodiesel,biomedical,and biochemical raw materials in southern China.However,yields fuctuate widely due to the lack of high-yielding,high-quality,stable cultivars.Therefore,the objectives of this study were to evaluate three species and one variety among 149 nationwide Sapindus species and screen for elite accessions which would serve as Sapindus breeding materials.Accessions were evaluated on 19 agro-morphological traits by correlation analysis and principal component analysis.These displayed substantial diversity and a broad range of economic traits.In particular,accessions of Sapindus mukorossi and Sapindus rarak had more variation in economic traits than Sapindus delavayi and Sapindus rarak var.velutinus.Increased saponin accumulation may be achieved at the cost of seed oil production.Thirty elite accessions for oil and saponin production,and for comprehensive utilization were screened and accessions no.80,110,and 112 had significant potential to produce high yields.These elite accessions will facilitate the identification of genetic determinants of valuable traits and the effective utilization of trait variability in Sapindus breeding.展开更多
Relatively little is known about the relationship between Bufo gargarizans populations from Zhoushan Archipelago and nearby continental regions on the Pacific coast of eastern China.In this paper,155 new specimens of ...Relatively little is known about the relationship between Bufo gargarizans populations from Zhoushan Archipelago and nearby continental regions on the Pacific coast of eastern China.In this paper,155 new specimens of B.gargarizans from Zhoushan Archipelago and adjacent continents and 71 published specimens of B.gargarizans from China's Mainland were studied.Phylogeographical and dating analyses of B.gargarizans were performed using mitochondrial DNA sequencing with a length of 1436 bp.A mt DNA tree that indicated seven major clades was obtained.The earliest split in the mt DNA tree corresponding to the divergence of populations from the western highland region occurred approximately 4.0 million years ago(mya).A subsequent clade occurred about 3.4 mya,with cladogenesis continuing toward the end of the Pleistocene.The continental clades were distributed in the western,central and northeastern regions of China.Zhoushan Archipelago clades consisted of two largely geographically overlapping subclades with the mt DNA divergence time of 0.73 mya.These results indicated there was extensive dispersal after vicariance.The B.gargarizans populations on Zhoushan Archipelago most probably originated from populations in nearby eastern continental regions of China.It was concluded that geological uplifting during the Pliocene and several sea-level changes in Pleistocene might have influenced the divergence and population demographical history of this species.展开更多
The efficiency of the seaport has been variously studied utilizing either data envelopment analysis( DEA) or stochastic Frontier analysis( SFA). Given the strengths and weaknesses associated with these two approaches,...The efficiency of the seaport has been variously studied utilizing either data envelopment analysis( DEA) or stochastic Frontier analysis( SFA). Given the strengths and weaknesses associated with these two approaches, applying both models to compute efficiency estimates for the 11 seaports of the China and Korea from 2012-2016 and comparing the results obtained. Main finding facts of this paper are as follows:( i) there are some differences among relative efficiency levels,but almost no differences among efficiency ranks in DEA and SFA results.( ii) The tendency of VRS is stronger in Chinese coastal seaports during the past several years.( iii) The values among seaports in SFA model are relatively smaller than those in the DEA models. The results show that the efficiency of major seaports in Korea is far lower than that of ports in China.展开更多
Background Dietary bamboo leaf flavonoids(BLFs)are rarely used in poultry production,and it is unknown whether they influence meat texture profile,perceived color,or microstructure.Results A total of 720 one-day-old A...Background Dietary bamboo leaf flavonoids(BLFs)are rarely used in poultry production,and it is unknown whether they influence meat texture profile,perceived color,or microstructure.Results A total of 720 one-day-old Arbor Acres broilers were supplemented with a basal diet with 20 mg bacitracin/kg,50 mg BLFs/kg,or 250 mg BLFs/kg or without additions.Data showed that the dietary BLFs significantly(P<0.05)changed growth performance and the texture profile.In particular,BLFs increased birds’average daily gain and average daily feed intake,decreased the feed:gain ratio and mortality rate,improved elasticity of breast meat,enhanced the gumminess of breast and leg meat,and decreased the hardness of breast meat.Moreover,a significant(P<0.05)increase in redness(a*)and chroma(c*)of breast meat and c*and water-holding capacity of leg meat was found in BLF-supplemented broilers compared with control broilers.In addition,BLFs supplementation significantly decreased(P<0.05)theβ-sheet ratio and serum malondialdehyde and increased theβ-turn ratio of protein secondary structure,superoxide dismutase,and glutathione peroxidase of breast meat and total antioxidant capacity and catalase of serum.Based on the analysis of untargeted metabolome,BLFs treatment considerably altered 14 metabolites of the breast meat,including flavonoids,amino acids,and organic acids,as well as phenolic and aromatic compounds.Conclusions Dietary BLFs supplementation could play a beneficial role in improving meat quality and sensory color in the poultry industry by changing protein secondary structures and modulating metabolites.展开更多
A series of CeO_(2)-TiO_(2)mixed oxides supports with various Ce/Ti molar ratio were synthesized by modified coprecipitation method. The corresponding Pt loaded(0.5 wt% Pt) catalysts were prepared by electronless depo...A series of CeO_(2)-TiO_(2)mixed oxides supports with various Ce/Ti molar ratio were synthesized by modified coprecipitation method. The corresponding Pt loaded(0.5 wt% Pt) catalysts were prepared by electronless deposition method and evaluated for the deep oxidation of n-hexane as a model VOCs. The results show that the CeO_(2)and TiOxnanoparticles can highly disperse into each other and form Ce_(2)Ti_(2)O_(7)solid solution with appropriate Ce/Ti molar ratio, which significantly improves their redox ability by enhancing the interaction between CeO_(2)and TiO_(x). The dispersibility of Pt species can also be adjusted by altering the Ce/Ti molar ratio, and Pt/CeTi-2/1 catalyst with Ce/Ti molar ratio of 2:1 exhibits the best Pt dispersibility that Pt species mainly exist as Pt single atoms. The high dispersion of Pt species in the Pt/CeO_(2)-TiO_(2)catalysts would promote the catalytic activity of VOCs oxidation with low T90% values(1000 ppm, GHSV = 15,000 h^(-1)), such as for n-hexane degradation with T90% of 139℃. The characterizations reveal that the superior activity is mainly related to possessing the more Pt2+species,adsorbed oxygen species and higher low-temperature reducibility owing to the strong interaction between highly dispersed Pt species and CeO_(2)-TiO_(2)as well as the promoted migration of lattice oxygen by the formation of more Ce_(2)Ti_(2)O_(7)species. Furthermore, the Pt/CeTi-2/1 catalyst also exhibits excellent stability for chlorinated and other non-chlorinated VOCs oxidation, making it very promising for real application under various operating conditions.展开更多
基金This work was supported by the National Basic Research Program of China （973 Program） under Grant No. 2010CB327804, the National Natural Science Foundation of China under Grant No. 61108058, the major project of Education Department in Zhejiang Province of China under Grant No. Z200909231 and the Qianjiang Talents Program of Zhejiang Province of China under Grant No. QJD0902005.
基金Project supported by the National Natural Science Foundation of China (Grant No.12074354)。
文摘We present a dynamic model of cavitation bubbles in a cluster,in which the effects of evaporation,condensation,and bubble-bubble interactions are taken into consideration.Under different ultrasound conditions,we examine how the dynamics of cavitation bubbles are affected by several factors,such as the locations of the bubbles,the ambient radius,and the number of bubbles.Herein the variations of bubble radius,energy,temperature,pressure,and the quantity of vapor molecules are analyzed.Our findings reveal that bubble-bubble interactions can restrict the expansion of bubbles,reduce the exchange of energy among vapor molecules,and diminish the maximum internal temperature and pressure when bursting.The ambient radius of bubbles can influence the intensities of their oscillations,with clusters comprised of smaller bubbles creating optimal conditions for generating high-temperature and high-pressure regions.Moreover,an increase in the number of bubbles can further inhibit cavitation activities.The frequency,pressure and waveform of the driving wave can also exert a significant influence on cavitation activities,with rectangular waves enhancing and triangular waves weakening the cavitation of bubbles in the cluster.These results provide a theoretical basis for understanding the dynamics of cavitation bubbles in a bubble cluster,and the factors that affect their behaviors.
基金supported partly by the Natural Science Foundation of Zhejiang Province,China(LGF21F020017).
文摘With the widespread use of Internet of Things(IoT)technology in daily life and the considerable safety risks of falls for elderly individuals,research on IoT-based fall detection systems has gainedmuch attention.This paper proposes an IoT-based spatiotemporal data processing framework based on a depthwise separable convolution generative adversarial network using skip-connection(Skip-DSCGAN)for fall detection.The method uses spatiotemporal data from accelerometers and gyroscopes in inertial sensors as input data.A semisupervised learning approach is adopted to train the model using only activities of daily living(ADL)data,which can avoid data imbalance problems.Furthermore,a quantile-based approach is employed to determine the fall threshold,which makes the fall detection frameworkmore robust.This proposed fall detection framework is evaluated against four other generative adversarial network(GAN)models with superior anomaly detection performance using two fall public datasets(SisFall&MobiAct).The test results show that the proposed method achieves better results,reaching 96.93% and 92.75% accuracy on the above two test datasets,respectively.At the same time,the proposed method also achieves satisfactory results in terms ofmodel size and inference delay time,making it suitable for deployment on wearable devices with limited resources.In addition,this paper also compares GAN-based semisupervised learning methods with supervised learning methods commonly used in fall detection.It clarifies the advantages of GAN-based semisupervised learning methods in fall detection.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(LY21A010016)the National Natural Science Foundation of China(11901550).
文摘In this paper, we investigate a blow-up phenomenon for a semilinear parabolic system on locally finite graphs. Under some appropriate assumptions on the curvature condition CDE’(n,0), the polynomial volume growth of degree m, the initial values, and the exponents in absorption terms, we prove that every non-negative solution of the semilinear parabolic system blows up in a finite time. Our current work extends the results achieved by Lin and Wu (Calc Var Partial Differ Equ, 2017, 56: Art 102) and Wu (Rev R Acad Cien Serie A Mat, 2021, 115: Art 133).
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ23F040001)the National Natural Science Foundation of China(Grant No.12204446)+1 种基金the Public Welfare Technology Research Project of Zhejiang Province(Grant No.LGC22E050006)the Quzhou Science and Technology Project of China(Grant No.2022K104).
文摘Quasi-bound state in the continuum(QBIC)resonance is gradually attracting attention and being applied in Goos-Hänchen(GH)shift enhancement due to its high quality(Q)factor and superior optical confinement.Currently,symmetry-protected QBIC resonance is often achieved by breaking the geometric symmetry,but few cases are achieved by breaking the material symmetry.This paper proposes a dielectric compound grating to achieve a high Q factor and high-reflection symmetry-protectede QBIC resonance based on material asymmetry.Theoretical calculations show that the symmetry-protected QBIC resonance achieved by material asymmetry can significantly increase the GH shift up to-980 times the resonance wavelength,and the maximum GH shift is located at the reflection peak with unity reflectance.This paper provides a theoretical basis for designing and fabricating high-performance GH shift tunable metasurfaces/dielectric gratings in the future.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12132015 and 11972336)。
文摘This work focuses on numerically studying hydrodynamic interaction between a passive particle and a self-propelled particle,termed a squirmer,by using a two-dimensional lattice Boltzmann method(LBM).It is found that the squirmer can capture a passive particle and propel it simultaneously,provided the passive particle is situated within the squirmer's wake.Our research shows that the critical capture distance,which determines whether the particle is captured,primarily depends on the intensity of the squirmer's dipolarity.The stronger dipolarity of squirmer results in an increased critical capture distance.Conversely,the Reynolds number is found to have minimal influence on this interaction.Interestingly,the passive particle,when driven by the squirmer's wake,contributes to a reduction in the squirmer's drag.This results in a mutual acceleration for both particles.Our findings can provide valuable perspectives for formulating the principles of reducing the drag of micro-swimmers and help to achieve the goal of using micro-swimmers to transport goods without physical tethers.
基金supported by the Science and Technology Development Fund of Macao SAR(FDCT0128/2022/A,0020/2023/RIB1,0111/2023/AFJ,005/2022/ALC)the Shandong Natural Science Foundation of China(ZR2020MA004)+2 种基金the National Natural Science Foundation of China(12071272)the MYRG 2018-00168-FSTZhejiang Provincial Natural Science Foundation of China(LQ23A010014).
文摘This study introduces a pre-orthogonal adaptive Fourier decomposition(POAFD)to obtain approximations and numerical solutions to the fractional Laplacian initial value problem and the extension problem of Caffarelli and Silvestre(generalized Poisson equation).As a first step,the method expands the initial data function into a sparse series of the fundamental solutions with fast convergence,and,as a second step,makes use of the semigroup or the reproducing kernel property of each of the expanding entries.Experiments show the effectiveness and efficiency of the proposed series solutions.
文摘This paper draws on the experience of the eighth plenary meeting of the ISO/TC 321, Transaction assurance in e-commerce, held in Hangzhou of China in November 2023, and explores potential ways in which developing countries in Africa can drive their development and contribute to global industrial progress by leveraging ISO/TC 321 standards. It provides practical recommendations for utilizing e-commerce standardization and related standards to stimulate economic growth and enhance business practices.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51920105004, 52102223, 52002081)。
文摘Metal tellurides(MTes) are highly attractive as promising anodes for high-performance potassium-ion batteries. The capacity attenuation of most reported MTe anodes is attributed to their poor electrical conductivity and large volume variation. The evolution mechanisms, dissolution properties, and corresponding manipulation strategies of intermediates(K-polytellurides, K-pTe_(x)) are rarely mentioned. Herein,we propose a novel structural engineering strategy to confine ultrafine CoTe_(2) nanodots in hierarchical nanogrid-in-nanofiber carbon substrates(CoTe_(2)@NC@NSPCNFs) for smooth immobilization of K-pTe_(x) and highly reversible conversion of CoTe_(2) by manipulating the intense electrochemical reaction process. Various in situ/ex situ techniques and density functional theory calculations have been performed to clarify the formation, transformation, and dissolution of K-pTe_(x)(K_(5)Te_(3) and K_(2)Te), as well as verifying the robust physical barrier and the strong chemisorption of K_(5)Te_(3) and K_(2)Te on S, N co-doped dual-type carbon substrates. Additionally, the hierarchical nanogrid-in-nanofiber nanostructure increases the chemical anchoring sites for K-pTe_(x), provides sufficient volume buffer space, and constructs highly interconnected conductive microcircuits, further propelling the battery reaction to new heights(3500 cycles at 2.0 A g^(-1)). Furthermore, the full cells further demonstrate the potential for practical applications. This work provides new insights into manipulating K-pTe_(x) in the design of ultralong-cycling MTe anodes for advanced PIBs.
基金supported by the National Natural Science Foundation of China(Grant Nos.12104216,12241403,and 61974061)the National Key R&D Program of China(Grant No.2021YFB3601600)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20140054)。
文摘We investigate the anisotropic band structure and its evolution under tensile strains along different crystallographic directions in bulk black phosphorus(BP)using angle-resolved photoemission spectroscopy and density functional theory.The results show that there are band crossings in the Z-L(armchair)direction.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFA1403202)the National Natural Science Foundation of China(Grant Nos.NSFC-12074335,11974095,5177115,11974095,and 12188101)the Natural Science Foundation of Shaanxi Province of China(Grant No.2022JM-028).
文摘Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential applications.In this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor transport method.We measured the magnetization,longitudinal resistivityρxx(T,H),Hall resistivityρxy(T,H),as well as performed calculations of the electronic band structure.It was found that V_(1/3)TaS_(2) is an A-type antiferromagnet with the Neel temperature T_(N)=6.20 K,and exhibits a negative magnetoresistance(MR)near T_(N).Both band structure calculations and Hall resistivity measurements demonstrated it is a magnetic semimetal.
基金Project supported by the Foundation of Agricultural Development of Hangzhou City, China
文摘Porcine circovirus type 2 (PCV2) is closely related to the postweaning multisystemic wasting syndrome (PMWS). In this study, the pig serum and tissue samples collected from different regions of Hangzhou District in Zhejiang Province of China between 2003 and 2005 were analyzed by enzyme-linked immunosorbent assay (ELISA) for PCV2 antibody and by polymerase chain reaction (PCR) for ORF2 gene. The results show that out of 1250 randomly collected serum samples, 500 sera (40%) were seropositive for PCV2. PCR results demonstrate that Hangzhou PCV2 with more than 50% Chinese PCV2 strains and French PCV2 formed Cluster A. Only one PCV2 from Hangzhou belonged to Cluster B with some other Chinese PCV2 and Netherlands’s isolates. Cluster C consisted of PCV2 isolates from China, US, Canada, UK and Germany. The results indicate that the PCV2 infection was widespread in Hangzhou.
基金the National Natural Science Foundation of China(11872353,91852102)the Natural Science Foundation of Zhejiang Province(LZ22A020004)。
文摘With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others without the protection of face masks,which greatly increases the risk of COVID-19 transmission.Therefore,the transmission mechanism of respiratory droplets in extremely crowded dining environments should be investigated.In this study,a numerical simulation of coughing at dining tables under two conditions was performed,namely the presence and absence of protective partitions,and the evaporation and condensation of aerosol droplets in the air were examined.By using the numerical method,we analyzed and verified the isolation effect of dining table partitions in the propagation of aerosol droplets.The effect of changes in room temperature on the diffusion of coughed aerosols when partitions were present was analyzed.We demonstrated how respiratory droplets spread through coughing and how these droplets affect others.Finally,we proposed a design for a dining table partition that minimizes the transmission of COVID-19.
基金supported by“the Fundamental Research Funds for the Central Universities”(2019YC19)the Special Foundation for National Science and Technology Basic Research Program of China(No.2019FY100803)the Fundamental Research Funds for the Central Universities of China from the Chinese Ministry of Education(2015ZCQLX-02)。
文摘Sapindus L.species are widely cultivated for biodiesel,biomedical,and biochemical raw materials in southern China.However,yields fuctuate widely due to the lack of high-yielding,high-quality,stable cultivars.Therefore,the objectives of this study were to evaluate three species and one variety among 149 nationwide Sapindus species and screen for elite accessions which would serve as Sapindus breeding materials.Accessions were evaluated on 19 agro-morphological traits by correlation analysis and principal component analysis.These displayed substantial diversity and a broad range of economic traits.In particular,accessions of Sapindus mukorossi and Sapindus rarak had more variation in economic traits than Sapindus delavayi and Sapindus rarak var.velutinus.Increased saponin accumulation may be achieved at the cost of seed oil production.Thirty elite accessions for oil and saponin production,and for comprehensive utilization were screened and accessions no.80,110,and 112 had significant potential to produce high yields.These elite accessions will facilitate the identification of genetic determinants of valuable traits and the effective utilization of trait variability in Sapindus breeding.
基金supported by the National Natural Science Foundation of China(Grant Nos.41541002 and 31372183)Natural Science Foundation of Zhejiang Province(Grant No.LY13C030002),China
文摘Relatively little is known about the relationship between Bufo gargarizans populations from Zhoushan Archipelago and nearby continental regions on the Pacific coast of eastern China.In this paper,155 new specimens of B.gargarizans from Zhoushan Archipelago and adjacent continents and 71 published specimens of B.gargarizans from China's Mainland were studied.Phylogeographical and dating analyses of B.gargarizans were performed using mitochondrial DNA sequencing with a length of 1436 bp.A mt DNA tree that indicated seven major clades was obtained.The earliest split in the mt DNA tree corresponding to the divergence of populations from the western highland region occurred approximately 4.0 million years ago(mya).A subsequent clade occurred about 3.4 mya,with cladogenesis continuing toward the end of the Pleistocene.The continental clades were distributed in the western,central and northeastern regions of China.Zhoushan Archipelago clades consisted of two largely geographically overlapping subclades with the mt DNA divergence time of 0.73 mya.These results indicated there was extensive dispersal after vicariance.The B.gargarizans populations on Zhoushan Archipelago most probably originated from populations in nearby eastern continental regions of China.It was concluded that geological uplifting during the Pliocene and several sea-level changes in Pleistocene might have influenced the divergence and population demographical history of this species.
基金Qianjiang Talent Plan,China(No.QJC1402014)National Natural Science Foundation of China(No.71473235)+1 种基金National Social Science Foundation of China(No.17BGJ018)Natural Science Foundation of Zhejiang Province,China(LY15G030027)
文摘The efficiency of the seaport has been variously studied utilizing either data envelopment analysis( DEA) or stochastic Frontier analysis( SFA). Given the strengths and weaknesses associated with these two approaches, applying both models to compute efficiency estimates for the 11 seaports of the China and Korea from 2012-2016 and comparing the results obtained. Main finding facts of this paper are as follows:( i) there are some differences among relative efficiency levels,but almost no differences among efficiency ranks in DEA and SFA results.( ii) The tendency of VRS is stronger in Chinese coastal seaports during the past several years.( iii) The values among seaports in SFA model are relatively smaller than those in the DEA models. The results show that the efficiency of major seaports in Korea is far lower than that of ports in China.
基金supported by Zhejiang New Century Higher Education Reform Project (No.yb06054): One of the research and practice achivements on construction of "standardized" features high-level specializaed personnel training system, Key Universities Research Institute of Humanities and Social Sciences in Zhejiang Province "Standardaition and Intellectual Property Management"Public Technological Innovative Service Platform of Standard Information and Quality Security on Zhejiang Province
基金supported by the National Natural Science Foundation of China(No.32002195)Zhejiang Provincial Leading Innovation and Entrepreneurship Team Project(No.2020R01015)+1 种基金“Leading Geese”Research and Development Plan of Zhejiang Province(No.2022C02059)Key R&D Projects of Zhejiang Province(No.2021C02013)。
文摘Background Dietary bamboo leaf flavonoids(BLFs)are rarely used in poultry production,and it is unknown whether they influence meat texture profile,perceived color,or microstructure.Results A total of 720 one-day-old Arbor Acres broilers were supplemented with a basal diet with 20 mg bacitracin/kg,50 mg BLFs/kg,or 250 mg BLFs/kg or without additions.Data showed that the dietary BLFs significantly(P<0.05)changed growth performance and the texture profile.In particular,BLFs increased birds’average daily gain and average daily feed intake,decreased the feed:gain ratio and mortality rate,improved elasticity of breast meat,enhanced the gumminess of breast and leg meat,and decreased the hardness of breast meat.Moreover,a significant(P<0.05)increase in redness(a*)and chroma(c*)of breast meat and c*and water-holding capacity of leg meat was found in BLF-supplemented broilers compared with control broilers.In addition,BLFs supplementation significantly decreased(P<0.05)theβ-sheet ratio and serum malondialdehyde and increased theβ-turn ratio of protein secondary structure,superoxide dismutase,and glutathione peroxidase of breast meat and total antioxidant capacity and catalase of serum.Based on the analysis of untargeted metabolome,BLFs treatment considerably altered 14 metabolites of the breast meat,including flavonoids,amino acids,and organic acids,as well as phenolic and aromatic compounds.Conclusions Dietary BLFs supplementation could play a beneficial role in improving meat quality and sensory color in the poultry industry by changing protein secondary structures and modulating metabolites.
基金supported by a grant from the National Key Research and Development Program of China (2016YFC0204300)the National Nature Science Foundation of China (21477109)。
文摘A series of CeO_(2)-TiO_(2)mixed oxides supports with various Ce/Ti molar ratio were synthesized by modified coprecipitation method. The corresponding Pt loaded(0.5 wt% Pt) catalysts were prepared by electronless deposition method and evaluated for the deep oxidation of n-hexane as a model VOCs. The results show that the CeO_(2)and TiOxnanoparticles can highly disperse into each other and form Ce_(2)Ti_(2)O_(7)solid solution with appropriate Ce/Ti molar ratio, which significantly improves their redox ability by enhancing the interaction between CeO_(2)and TiO_(x). The dispersibility of Pt species can also be adjusted by altering the Ce/Ti molar ratio, and Pt/CeTi-2/1 catalyst with Ce/Ti molar ratio of 2:1 exhibits the best Pt dispersibility that Pt species mainly exist as Pt single atoms. The high dispersion of Pt species in the Pt/CeO_(2)-TiO_(2)catalysts would promote the catalytic activity of VOCs oxidation with low T90% values(1000 ppm, GHSV = 15,000 h^(-1)), such as for n-hexane degradation with T90% of 139℃. The characterizations reveal that the superior activity is mainly related to possessing the more Pt2+species,adsorbed oxygen species and higher low-temperature reducibility owing to the strong interaction between highly dispersed Pt species and CeO_(2)-TiO_(2)as well as the promoted migration of lattice oxygen by the formation of more Ce_(2)Ti_(2)O_(7)species. Furthermore, the Pt/CeTi-2/1 catalyst also exhibits excellent stability for chlorinated and other non-chlorinated VOCs oxidation, making it very promising for real application under various operating conditions.
