A simplified theoretical model for the linear Rayleigh-Taylor instability of finite thickness elastic-plastic solid constantly accelerated by finite thickness viscous fluid is performed.With the irrotational assumptio...A simplified theoretical model for the linear Rayleigh-Taylor instability of finite thickness elastic-plastic solid constantly accelerated by finite thickness viscous fluid is performed.With the irrotational assumption,it is possible to consider viscosity,surface tension,elasticity or plasticity effects simultaneously.The model considers thicknesses at rigid wall boundary conditions with the velocity potentials,and deals with solid elastic-plastic transition and fluid viscosity based on the velocity continuity and force equilibrium at contact interface.The complete analytical expressions of the amplitude motion equation,the growth rate,and the instability boundary are obtained for arbitrary Atwood number,viscosity,thicknesses of solid and fluid.The thicknesses effects of two materials on the growth rate and the instability boundary are discussed.展开更多
Objective:To study the effects of MIPO and ORIF on stress degree and bone metabolism activity in patients with middle humeral shaft fractures.Methods: Patients with middle humeral shaft fractures who received surgical...Objective:To study the effects of MIPO and ORIF on stress degree and bone metabolism activity in patients with middle humeral shaft fractures.Methods: Patients with middle humeral shaft fractures who received surgical treatment in Mianyang Orthopedic Hospital between June 2010 and October 2015 were enrolled and randomly divided into MIPO group and ORIF group who were treated with minimally invasive plate oateosynthesis and open reduction internal fixation respectively. Before surgery as well as 1 d and 3 d after surgery, serum was collected to determine the contents of stress response molecules and bone metabolism markers.Results:1 d and 3 d after surgery, serum stress molecules PGE2, CRP, NE and E as well as bone resorption markers TRACP-5B,β-CTX, RANK and RANKL contents of both groups were higher than those before surgery while bone formation markers BGP, BALP, PINP and OPG contents were lower than those before surgery;serum stress molecules PGE2, CRP, NE and E as well as bone resorption markers TRACP-5B,β-CTX, RANK and RANKL contents of MIPO group were lower than those of ORFI group while bone formation markers BGP, BALP, PINP and OPG contents were higher than those of ORFI group.Conclusion: Compared with ORIF, MIPO for middle humeral shaft fractures can reduce stress response degree and improve bone metabolism.展开更多
Knots and links are fascinating and intricate topological objects.Their influence spans from DNA and molecular chemistry to vortices in superfluid helium,defects in liquid crystals and cosmic strings in the early univ...Knots and links are fascinating and intricate topological objects.Their influence spans from DNA and molecular chemistry to vortices in superfluid helium,defects in liquid crystals and cosmic strings in the early universe.Here we find that knotted structures also exist in a peculiar class of three-dimensional topological insulators—the Hopf insulators.In particular,we demonstrate that the momentum-space spin textures of Hopf insulators are twisted in a nontrivial way,which implies the presence of various knot and link structures.We further illustrate that the knots and nontrivial spin textures can be probed via standard time-of-flight images in cold atoms as preimage contours of spin orientations in stereographic coordinates.The extracted Hopf invariants,knots,and links are validated to be robust to typical experimental imperfections.Our work establishes the existence of knotted structures in Hopf insulators,which may have potential applications in spintronics and quantum information processing.展开更多
Photoresponsiveness of materials is critical to their tunability and efficiency in terminal applications.Photoresponsive metal-organic polyhedra(PMOPs)feature intrinsic pores and remote controllability,but aggregation...Photoresponsiveness of materials is critical to their tunability and efficiency in terminal applications.Photoresponsive metal-organic polyhedra(PMOPs)feature intrinsic pores and remote controllability,but aggregation of PMOPs in solid state hampers their photoresponsiveness seriously.Herein,we report the construction of a new PMOP(Cu_(24)(C_(16)H_(12)N_(2)O_(4))_(12)(C_(18)H_(22)O_(5))12,denoted as MOP-PR-LA),where long alkyl(LA)chains act as the intermolecular poles,propping against adjacent PMOP molecules to create individual microenvironment benefiting the isomerization of photoresponsive(PR)moieties.Upon ultraviolet(UV)-and visible-light irradiation,MOP-PR-LA is much easier to isomerize than the counterpart MOP-PR without LA.For propylene adsorption,MOP-PR has a low change of adsorption capacity(9.9%),while that of MOP-PR-LA reaches 58.6%.Density functional theory calculations revealed that PR in the cis state has a negative effect on adsorption,while the trans state of PR favors adsorption.This work might open an avenue for the construction of photoresponsive materials with high responsiveness and controllability.展开更多
On December 7,2022,the Chinese government optimized the current epidemic prevention and control policy,and no longer adopted the zero-COVID policy and mandatory quarantine measures.Based on the above policy changes,th...On December 7,2022,the Chinese government optimized the current epidemic prevention and control policy,and no longer adopted the zero-COVID policy and mandatory quarantine measures.Based on the above policy changes,this paper establishes a compartment dynamics model considering age distribution,home isolation and vaccinations.Parameter estimation was performed using improved least squares and Nelder-Mead simplex algorithms combined with modified case data.Then,using the estimated parameter values to predict a second wave of the outbreak,the peak of severe cases will reach on 8 May 2023,the number of severe cases will reach 206,000.Next,it is proposed that with the extension of the effective time of antibodies obtained after infection,the peak of severe cases in the second wave of the epidemic will be delayed,and the final scale of the disease will be reduced.When the effectiveness of antibodies is 6 months,the severe cases of the second wave will peak on July 5,2023,the number of severe cases is 194,000.Finally,the importance of vaccination rates is demonstrated,when the vaccination rate of susceptible people under 60 years old reaches 98%,and the vaccination rate of susceptible people over 60 years old reaches 96%,the peak of severe cases in the second wave of the epidemic will be reached on 13 July 2023,when the number of severe cases is 166,000.展开更多
The problem of limited minority class data is encountered in manyclass imbalanced applications, but has received little attention. Synthetic over-sampling, as popular class-imbalance learning methods, could introduce ...The problem of limited minority class data is encountered in manyclass imbalanced applications, but has received little attention. Synthetic over-sampling, as popular class-imbalance learning methods, could introduce much noise when minority class has limited data since the synthetic samples are not i.i.d. samples of minority class. Mos t sophisticated synthetic sampling methods tackle this problem by denoising or generating samples more consistent with ground-truth data distribution. But their assumptions about true noise or ground-truth data distribution may not hold. To adapt synthetic sampling to the problem of limited minority class data, the proposed Traso framework treats synthetic minority class samples as an additional data source, and exploits transfer learning to transfer knowledge from them to minority class. As an implementation, TrasoBoost method firstly generates synthetic samples to balance class sizes. Then in each boosting iteration, the weights of synthetic samples and original data decrease and increase respectively when being misclassified, and remain unchanged otherwise. The misclassified synthetic samples are potential noise, and thus have smaller influence in the following iterations. Besides, the weights of minority class instances have greater change than those of majority class instances to be more influential. And only original data are used to estimate error rate to be immune from noise. Finally, since the synthetic samples are highly related to minority class, all of the weak learners are aggregated for prediction. Experimental results show TrasoBoost outperforms many popular class-imbalance learning methods.展开更多
In this study,the Huadian oil shale(HD-R)and Balikun oil shale(BLK-R)were pyrolyzed in a fixed-bed pyrolyzer at 360–530℃.Based on the migration and conversion of organic carbon,their pyrolysis characteristics were i...In this study,the Huadian oil shale(HD-R)and Balikun oil shale(BLK-R)were pyrolyzed in a fixed-bed pyrolyzer at 360–530℃.Based on the migration and conversion of organic carbon,their pyrolysis characteristics were investigated and compared.The aliphaticity of Huadian kerogen(HD-K)and Balikun kerogen(BLK-K)are 80.53%and 52.83%,respectively.The HD-K contains more C=O,which will render the depolymerization and decomposition of kerogen to occur at low temperatures to produce volatile matters.Thus,the cumulative conversion of the Huadian shale oil is greater than the Balikun shale oil at 390–435℃.The aliphatic carbons of the BLK-K are mainly present as short methylene chains attached to aromatic rings.They will leave the kerogen matrix with the breakage of relatively weaker CeC bonds at β-sites from aromatic rings at medium temperatures.By contrast,aliphatic carbons of the HD-K are dominated by long aliphatic chains.High temperature is necessary to break other stronger CeC to form shale oil and gaseous species,which appears to make the oil accumulation conversion of BLK-R exceed that of HD-R at 450–510℃.展开更多
基金Project supported by of the Science Challenge Project of China(Grant No.TZ2018001)。
文摘A simplified theoretical model for the linear Rayleigh-Taylor instability of finite thickness elastic-plastic solid constantly accelerated by finite thickness viscous fluid is performed.With the irrotational assumption,it is possible to consider viscosity,surface tension,elasticity or plasticity effects simultaneously.The model considers thicknesses at rigid wall boundary conditions with the velocity potentials,and deals with solid elastic-plastic transition and fluid viscosity based on the velocity continuity and force equilibrium at contact interface.The complete analytical expressions of the amplitude motion equation,the growth rate,and the instability boundary are obtained for arbitrary Atwood number,viscosity,thicknesses of solid and fluid.The thicknesses effects of two materials on the growth rate and the instability boundary are discussed.
文摘Objective:To study the effects of MIPO and ORIF on stress degree and bone metabolism activity in patients with middle humeral shaft fractures.Methods: Patients with middle humeral shaft fractures who received surgical treatment in Mianyang Orthopedic Hospital between June 2010 and October 2015 were enrolled and randomly divided into MIPO group and ORIF group who were treated with minimally invasive plate oateosynthesis and open reduction internal fixation respectively. Before surgery as well as 1 d and 3 d after surgery, serum was collected to determine the contents of stress response molecules and bone metabolism markers.Results:1 d and 3 d after surgery, serum stress molecules PGE2, CRP, NE and E as well as bone resorption markers TRACP-5B,β-CTX, RANK and RANKL contents of both groups were higher than those before surgery while bone formation markers BGP, BALP, PINP and OPG contents were lower than those before surgery;serum stress molecules PGE2, CRP, NE and E as well as bone resorption markers TRACP-5B,β-CTX, RANK and RANKL contents of MIPO group were lower than those of ORFI group while bone formation markers BGP, BALP, PINP and OPG contents were higher than those of ORFI group.Conclusion: Compared with ORIF, MIPO for middle humeral shaft fractures can reduce stress response degree and improve bone metabolism.
基金supported by the ARL,the IARPA Logi Q program,and the AFOSR MURI programsupported by Tsinghua University for their visits+1 种基金the support from NSF under Grant No.PHY1402971.supported by JQI-NSF-PFC and LPS-MPO-CMTC at the final stage of this paper
文摘Knots and links are fascinating and intricate topological objects.Their influence spans from DNA and molecular chemistry to vortices in superfluid helium,defects in liquid crystals and cosmic strings in the early universe.Here we find that knotted structures also exist in a peculiar class of three-dimensional topological insulators—the Hopf insulators.In particular,we demonstrate that the momentum-space spin textures of Hopf insulators are twisted in a nontrivial way,which implies the presence of various knot and link structures.We further illustrate that the knots and nontrivial spin textures can be probed via standard time-of-flight images in cold atoms as preimage contours of spin orientations in stereographic coordinates.The extracted Hopf invariants,knots,and links are validated to be robust to typical experimental imperfections.Our work establishes the existence of knotted structures in Hopf insulators,which may have potential applications in spintronics and quantum information processing.
基金the National Key R&D Program of China(No.2022YFB3806800)the National Science Fund for Distinguished Young Scholars(No.22125804)+1 种基金the National Natural Science Foundation of China(No.22078155)the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Photoresponsiveness of materials is critical to their tunability and efficiency in terminal applications.Photoresponsive metal-organic polyhedra(PMOPs)feature intrinsic pores and remote controllability,but aggregation of PMOPs in solid state hampers their photoresponsiveness seriously.Herein,we report the construction of a new PMOP(Cu_(24)(C_(16)H_(12)N_(2)O_(4))_(12)(C_(18)H_(22)O_(5))12,denoted as MOP-PR-LA),where long alkyl(LA)chains act as the intermolecular poles,propping against adjacent PMOP molecules to create individual microenvironment benefiting the isomerization of photoresponsive(PR)moieties.Upon ultraviolet(UV)-and visible-light irradiation,MOP-PR-LA is much easier to isomerize than the counterpart MOP-PR without LA.For propylene adsorption,MOP-PR has a low change of adsorption capacity(9.9%),while that of MOP-PR-LA reaches 58.6%.Density functional theory calculations revealed that PR in the cis state has a negative effect on adsorption,while the trans state of PR favors adsorption.This work might open an avenue for the construction of photoresponsive materials with high responsiveness and controllability.
基金supported by the National Science Fund for Distinguished Young Scholars(22125804)the National Natural Science Foundation of China(22078155)the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions。
基金supported by the National Natural Science Foundation of China(12022113 and 12271314)Henry Fok Foundation for Young Teachers(171002)Outstanding Young Talents Support Plan of Shanxi Province.
文摘On December 7,2022,the Chinese government optimized the current epidemic prevention and control policy,and no longer adopted the zero-COVID policy and mandatory quarantine measures.Based on the above policy changes,this paper establishes a compartment dynamics model considering age distribution,home isolation and vaccinations.Parameter estimation was performed using improved least squares and Nelder-Mead simplex algorithms combined with modified case data.Then,using the estimated parameter values to predict a second wave of the outbreak,the peak of severe cases will reach on 8 May 2023,the number of severe cases will reach 206,000.Next,it is proposed that with the extension of the effective time of antibodies obtained after infection,the peak of severe cases in the second wave of the epidemic will be delayed,and the final scale of the disease will be reduced.When the effectiveness of antibodies is 6 months,the severe cases of the second wave will peak on July 5,2023,the number of severe cases is 194,000.Finally,the importance of vaccination rates is demonstrated,when the vaccination rate of susceptible people under 60 years old reaches 98%,and the vaccination rate of susceptible people over 60 years old reaches 96%,the peak of severe cases in the second wave of the epidemic will be reached on 13 July 2023,when the number of severe cases is 166,000.
基金The authors wish to thank the associate editor and anonymous reviewers for their helpful comments and suggestions. This work was supported by the National Key R&D Program of China (2017YFB1002801)the National Natural Science Foundation of China (Grant Nos. 61473087, 61573104)the Natural Science Foundation of Jiangsu Province (BK20141340), and partially supported by the Collaborative Innovation Center of Novel Software Technology and Industrialization.
文摘The problem of limited minority class data is encountered in manyclass imbalanced applications, but has received little attention. Synthetic over-sampling, as popular class-imbalance learning methods, could introduce much noise when minority class has limited data since the synthetic samples are not i.i.d. samples of minority class. Mos t sophisticated synthetic sampling methods tackle this problem by denoising or generating samples more consistent with ground-truth data distribution. But their assumptions about true noise or ground-truth data distribution may not hold. To adapt synthetic sampling to the problem of limited minority class data, the proposed Traso framework treats synthetic minority class samples as an additional data source, and exploits transfer learning to transfer knowledge from them to minority class. As an implementation, TrasoBoost method firstly generates synthetic samples to balance class sizes. Then in each boosting iteration, the weights of synthetic samples and original data decrease and increase respectively when being misclassified, and remain unchanged otherwise. The misclassified synthetic samples are potential noise, and thus have smaller influence in the following iterations. Besides, the weights of minority class instances have greater change than those of majority class instances to be more influential. And only original data are used to estimate error rate to be immune from noise. Finally, since the synthetic samples are highly related to minority class, all of the weak learners are aggregated for prediction. Experimental results show TrasoBoost outperforms many popular class-imbalance learning methods.
基金the National Basic Research Program of China(Grant 2014CB744301).
文摘In this study,the Huadian oil shale(HD-R)and Balikun oil shale(BLK-R)were pyrolyzed in a fixed-bed pyrolyzer at 360–530℃.Based on the migration and conversion of organic carbon,their pyrolysis characteristics were investigated and compared.The aliphaticity of Huadian kerogen(HD-K)and Balikun kerogen(BLK-K)are 80.53%and 52.83%,respectively.The HD-K contains more C=O,which will render the depolymerization and decomposition of kerogen to occur at low temperatures to produce volatile matters.Thus,the cumulative conversion of the Huadian shale oil is greater than the Balikun shale oil at 390–435℃.The aliphatic carbons of the BLK-K are mainly present as short methylene chains attached to aromatic rings.They will leave the kerogen matrix with the breakage of relatively weaker CeC bonds at β-sites from aromatic rings at medium temperatures.By contrast,aliphatic carbons of the HD-K are dominated by long aliphatic chains.High temperature is necessary to break other stronger CeC to form shale oil and gaseous species,which appears to make the oil accumulation conversion of BLK-R exceed that of HD-R at 450–510℃.
