As a complement to X-ray computed tomography(CT),neutron tomography has been extensively used in nuclear engineer-ing,materials science,cultural heritage,and industrial applications.Reconstruction of the attenuation m...As a complement to X-ray computed tomography(CT),neutron tomography has been extensively used in nuclear engineer-ing,materials science,cultural heritage,and industrial applications.Reconstruction of the attenuation matrix for neutron tomography with a traditional analytical algorithm requires hundreds of projection views in the range of 0°to 180°and typically takes several hours to complete.Such a low time-resolved resolution degrades the quality of neutron imaging.Decreasing the number of projection acquisitions is an important approach to improve the time resolution of images;however,this requires efficient reconstruction algorithms.Therefore,sparse-view reconstruction algorithms in neutron tomography need to be investigated.In this study,we investigated the three-dimensional reconstruction algorithm for sparse-view neu-tron CT scans.To enhance the reconstructed image quality of neutron CT,we propose an algorithm that uses OS-SART to reconstruct images and a split Bregman to solve for the total variation(SBTV).A comparative analysis of the performances of each reconstruction algorithm was performed using simulated and actual experimental data.According to the analyzed results,OS-SART-SBTV is superior to the other algorithms in terms of denoising,suppressing artifacts,and preserving detailed structural information of images.展开更多
The most critical part of a neutron computed tomography(NCT) system is the image processing algorithm,which directly affects the quality and speed of the reconstructed images.Various types of noise in the system can d...The most critical part of a neutron computed tomography(NCT) system is the image processing algorithm,which directly affects the quality and speed of the reconstructed images.Various types of noise in the system can degrade the quality of the reconstructed images.Therefore,to improve the quality of the reconstructed images of NCT systems,efficient image processing algorithms must be used.The anisotropic diffusion filtering(ADF) algorithm can not only effectively suppress the noise in the projection data,but also preserve the image edge structure information by reducing the diffusion at the image edges.Therefore,we propose the application of the ADF algorithm for NCT image reconstruction.To compare the performance of different algorithms in NCT systems,we reconstructed images using the ordered subset simultaneous algebraic reconstruction technique(OS-SART) algorithm with different regular terms as image processing algorithms.In the iterative reconstruction,we selected two image processing algorithms,the Total Variation and split Bregman solved total variation algorithms,for comparison with the performance of the ADF algorithm.Additionally,the filtered back-projection algorithm was used for comparison with an iterative algorithm.By reconstructing the projection data of the numerical and clock models,we compared and analyzed the effects of each algorithm applied in the NCT system.Based on the reconstruction results,OS-SART-ADF outperformed the other algorithms in terms of denoising,preserving the edge structure,and suppressing artifacts.For example,when the 3D Shepp–Logan was reconstructed at 25 views,the root mean square error of OS-SART-ADF was the smallest among the four iterative algorithms,at only 0.0292.The universal quality index,mean structural similarity,and correlation coefficient of the reconstructed image were the largest among all algorithms,with values of 0.9877,0.9878,and 0.9887,respectively.展开更多
We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),a...We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),and ensure thatαis positive to avoid any singularity problems.The equation derived for the shadow radius indicates that it increases as the event horizon radius increases,making it an independent variable for determining BH temperature.By investigating the PT curve in relation to shadows,we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH PT.Furthermore,the results indicate that an increase in the parameterαcorresponds to a decrease in the temperature of the BH.By utilizing the relationship between the temperature and the shadow radius,it is possible to obtain the thermal profile of the Gauss-Bonnet AdS BH.It is evident that there is an N-type variation in temperature for pressures P<P_(c).Additionally,as the parameterαincreases,the region covered by shadow expands while the temperature decreases.The utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior.展开更多
Neutron computed tomography(NCT)is widely used as a noninvasive measurement technique in nuclear engineering,thermal hydraulics,and cultural heritage.The neutron source intensity of NCT is usually low and the scan tim...Neutron computed tomography(NCT)is widely used as a noninvasive measurement technique in nuclear engineering,thermal hydraulics,and cultural heritage.The neutron source intensity of NCT is usually low and the scan time is long,resulting in a projection image containing severe noise.To reduce the scanning time and increase the image reconstruction quality,an effective reconstruction algorithm must be selected.In CT image reconstruction,the reconstruction algorithms can be divided into three categories:analytical algorithms,iterative algorithms,and deep learning.Because the analytical algorithm requires complete projection data,it is not suitable for reconstruction in harsh environments,such as strong radia-tion,high temperature,and high pressure.Deep learning requires large amounts of data and complex models,which cannot be easily deployed,as well as has a high computational complexity and poor interpretability.Therefore,this paper proposes the OS-SART-PDTV iterative algorithm,which uses the ordered subset simultaneous algebraic reconstruction technique(OS-SART)algorithm to reconstruct the image and the first-order primal–dual algorithm to solve the total variation(PDTV),for sparse-view NCT three-dimensional reconstruction.The novel algorithm was compared with other algorithms(FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV)by simulating the experimental data and actual neutron projection experiments.The reconstruction results demonstrate that the proposed algorithm outperforms the FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV algorithms in terms of preserving edge structure,denoising,and suppressing artifacts.展开更多
Objective To retrospectively identify risk factors and the prognosis for new-onset atrial fibrillation (AF)after implantation of dual-chamber pacemakers in elderly patients.Methods Consecutive patients aged >65year...Objective To retrospectively identify risk factors and the prognosis for new-onset atrial fibrillation (AF)after implantation of dual-chamber pacemakers in elderly patients.Methods Consecutive patients aged >65years who underwent their first implantation of a dual-chamber permanent pacemaker in Beijing Anzhen Hospital from October 2013to May 2016were enrolled.Their complete program- ming and follow-up data were recorded.Follow-up end points included new-onset AF and major adverse cardiovascular and cerebrovascular events.Restdts Altogether,322patients were enrolled,with new-onset AF observed in 79(24.5%)during their follow-up.Multivariable analysis identified four independent predictors of new-onset AF in elderly patients after pacemaker implantation:hypertension (HR =3.040, 95%CI:1.09-3.05,P =0.00),age (HR =1.966,95%CI:1.57-3.68,P =0.01);left atrial enlargement (HR =1.645,95%CI:1.05-1.25,P = 0.03);high ventricular pacing rate (HR =1.137,95%CI:1.01-1.06,P =0.01).Univariable analysis indicated that the CHA2DS2-VASc score was also a risk factor for AF (HR =1.368,95%CI:1.178-1.589,P =0.002),whereas multivariable regression analysis did not. Kaplan-Meier survival analysis showed that the risk for ischemic stroke was significantly higher in the new-onset AF group than in the non-AF group (P <0.05).Conclusion Hypertension,age,left atrial enlargement,and high ventricular pacing rate were independent predictors of new-onset AF in elderly patients after implantation of a permanent pacemaker.New-onset AF increased the risk for ischemic stroke.展开更多
The oriented(CoIr)_(100-x)P_x(P = B, Ni, and SiO_2) soft magnetic films are prepared. Their morphology is measured using transmission electron microscopy(TEM), and reveals that these films exhibit good crystallinity a...The oriented(CoIr)_(100-x)P_x(P = B, Ni, and SiO_2) soft magnetic films are prepared. Their morphology is measured using transmission electron microscopy(TEM), and reveals that these films exhibit good crystallinity and high degree of the c-axis orientation. The magnetic properties are thoroughly investigated as a function of doping x. Our results show that all of these films possess negative magnetocrystalline anisotropy as required by possible applications. Both the intrinsic and extrinsic contributions are considered to interpret the broadening of the ferromagnetic resonance spectral linewidth. The intrinsic Gilbert damping is identified as the main cause of the linewidth broadening, while the extrinsic part originating from inhomogeneities only plays a minor role. More interestingly, our results show that the damping constant can be controlled by using the doping method.展开更多
1-(4-ethylphenyl)-nonane-1,3-dione(0206)is an oil-soluble liquid molecule with rod-like structure.In this study,the chelate(0206-Fe)with octahedral structure was prepared by the reaction of ferric chloride and 1,3-dik...1-(4-ethylphenyl)-nonane-1,3-dione(0206)is an oil-soluble liquid molecule with rod-like structure.In this study,the chelate(0206-Fe)with octahedral structure was prepared by the reaction of ferric chloride and 1,3-diketone.The experimental results show that when using 0206 and a mixed solution containing 60%0206-Fe and 40%0206(0206-Fe(60%))as lubricants of the steel friction pairs,superlubricity can be achieved(0.007,0.006).But their wear scar diameters(WSD)were very large(532µm,370µm),which resulted in the pressure of only 44.3 and 61.8 MPa in the contact areas of the friction pairs.When 0206-Fe(60%)was mixed with PAO6,it was found that the friction coefficient(COF)decreased with increase of 0206-Fe(60%)in the solution.When the ratio of 0206-Fe(60%)to PAO6 was 8:2(PAO6(20%)),it exhibited better comprehensive tribological properties(232.3 MPa).Subsequent studies have shown that reducing the viscosity of the base oil in the mixed solution helped to reduce COF and increased WSD.Considering the COF,contact pressure,and running-in time,it was found that the mixed lubricant(Oil3(20%))prepared by the base oil with a viscosity of 19.7 mPa·s(Oil3)and 0206-Fe(60%)exhibited the best tribological properties(0.007,161.4 MPa,3,100 s).展开更多
In this work,the optical appearance of an asymmetric thin-shell wormhole with a Bardeen profile is studied.To initiate the process,we need to construct an asymmetric thin-shell wormhole utilizing the cut-and-paste tec...In this work,the optical appearance of an asymmetric thin-shell wormhole with a Bardeen profile is studied.To initiate the process,we need to construct an asymmetric thin-shell wormhole utilizing the cut-and-paste technique proposed by Visser and subsequently ascertain its pertinent physical quantities such as the radius of the photon sphere and critical impact parameters for different values of magnetic charge g.Then,the effective potential and motion behavior of photons are also investigated within the framework of asymmetric thin-shell wormholes with a Bardeen profile.It can be found that the effective potential,ray trajectory,and azimuthal angle of the thin-shell wormhole exhibit a strong correlation with the mass ratio of black holes.By considering the accretion disk as the sole background light source,we observe additional photon rings and lensing bands in the optical appearance of the asymmetric thin-shell wormhole with a Bardeen profile compared to those exhibited by the Bardeen black hole.One can find that there is an increase in the size of the specific additional light bands with increasing magnetic charge g,which is different from the black hole case.These exceptionally luminous rings can serve as a robust criterion for the identification and characterization of the thin-shell wormhole spacetime.展开更多
In this paper,we study the optical properties of asymmetric thin-shell wormholes(ATWs)under torsion charge.Utilizing the cut-and-paste method developed by Visser,we construct these wormholes and determine their key ph...In this paper,we study the optical properties of asymmetric thin-shell wormholes(ATWs)under torsion charge.Utilizing the cut-and-paste method developed by Visser,we construct these wormholes and determine their key physical properties,such as the radius of the photon sphere and critical impact parameters,under different torsion charges.Furthermore,we investigate the effective potential and behavior of photon motion within the wormhole spacetime,identifying a relationship between photon trajectories and impact parameters.The study focuses on scenarios where thin accretion disks act as the primary light source.It reveals that the optical features of ATWs under torsion charge significantly differ from those of black holes(BHs).Notably,an increase in torsion charge leads to a reduction in the sizes of both extra photon rings and lensing bands,which serve as important markers for distinguishing and characterizing ATW spacetimes from those of BHs.展开更多
In this paper,the phase structure of the Hayward-anti-de Sitter(AdS)black hole(BH)is studied using shadow formalism.It has been found that the shadow radius is a monotonic function of the horizon radius and can theref...In this paper,the phase structure of the Hayward-anti-de Sitter(AdS)black hole(BH)is studied using shadow formalism.It has been found that the shadow radius is a monotonic function of the horizon radius and can therefore play an equivalent role to the horizon radius in characterizing the thermodynamics of the Hayward-AdS BH.The thermodynamic phase transition(PT)of the Hayward-AdS BH is investigated with the shadow radius.It is shown that as the magnetic charge increases,the shadow radius becomes larger,while the coexistence temperature becomes lower.The thermal profile of the Hayward-AdS BH is established by combining the temperature diagram and the shadow cast diagram,which shows that for a fixed magnetic charge,the temperature of the Hayward-AdS BH increases with the pressure whereas the region of the thermal profile decreases with the pressure.In particular,the temperature of the Hayward-AdS BH follows an N-type change trend when it is smaller than the critical temperature.It implies that the BH shadow may be used to investigate the thermodynamics of the Hayward-AdS BH.展开更多
Digital light processing(DLP)of structurally complex poly(ethylene glycol)(PEG)hydrogels with high mechanical toughness represents a long-standing challenge in thefield of 3D printing.Here,we report a 3D printing appro...Digital light processing(DLP)of structurally complex poly(ethylene glycol)(PEG)hydrogels with high mechanical toughness represents a long-standing challenge in thefield of 3D printing.Here,we report a 3D printing approach for the high-resolution manufacturing of structurally complex and mechanically strong PEG hydrogels via heat-assisted DLP.Instead of using aqueous solutions of photo-crosslinkable monomers,PEG macromonomer melts werefirst printed in the absence of water,resulting in bulk PEG networks.Then,post-printing swelling of the printed networks was achieved in water,producing high-fidelity 3D hydrogels with complex structures.By employing a dual-macromonomer resin containing a PEG-based four-arm macrophotoinitiator,“all-PEG”hydrogel constructs were pro-duced with compressive toughness up to 1.3 MJ m^(-3).By this approach,porous 3D hydrogel scaffolds with trabecular-like architecture were fabricated,and the scaf-fold surface supported cell attachment and the formation of a monolayer mimicking bone-lining cells.This study highlights the promises of heat-assisted DLP of PEG photopolymers for hydrogel fabrication,which may accelerate the development of 3D tissue-like constructs for regenerative medicine.展开更多
Dear Editor,Since its appearance in May 2022,monkeypox has spread to>100 countries and afflicted tens of thousands of people.Individuals infected with monkeypox present a fever,an extensive characteristic rash,and ...Dear Editor,Since its appearance in May 2022,monkeypox has spread to>100 countries and afflicted tens of thousands of people.Individuals infected with monkeypox present a fever,an extensive characteristic rash,and usually swollen lymph nodes(Chatterjee et al.,2022).The number of confirmed cases worldwide continues to grow at a rapid rate,but the treatment to this highly infectious viral disease is still very limited.Identification of new targeted-therapies will be crucial to control of this emerging public health threat.展开更多
Background Rickettsia and related diseases have been identified as significant global public health threats.This study involved comprehensive field and systematic investigations of various rickettsial organisms in Yun...Background Rickettsia and related diseases have been identified as significant global public health threats.This study involved comprehensive field and systematic investigations of various rickettsial organisms in Yunnan Province.Methods Between May 18,2011 and November 23,2020,field investigations were conducted across 42 counties in Yunnan Province,China,encompassing small mammals,livestock,and ticks.Preliminary screenings for Rickettsiales involved amplifying the 16S rRNA genes,along with additional genus-or species-specific genes,which were subse-quently confrmed through sequencing results.Sequence comparisons were carried out using the Basic Local Align-ment Search Tool(BLAST).Phylogenetic relationships were analyzed using the default parameters in the Molecular Evolutionary Genetics Analysis(MEGA)program.The chi-squared test was used to assess the diversities and compo-nent ratios of rickettsial agents across various parameters.Results A total of 7964 samples were collected from small mammals,livestock,and ticks through Yunnan Province and submitted for screening for rickettsial organisms.Sixteen rickettsial species from the genera Rickettsia,Anaplasma,Ehrlichia,Neoehrlichia,and Wolbachia were detected,with an overall prevalence of 14.72%.Among these,11 species were identifed as pathogens or potential pathogens to humans and livestock.Specifically,10 rickettsial organisms were widely found in 42.11%(24 out of 57)of small mammal species.High prevalence was observed in Dremomys samples at 5.60%,in samples from regions with latitudes above 4000 m or alpine meadows,and in those obtained from Yuanmou County.Anaplasma phagocytophilum and Candidatus Neoehrlichia mikurensis were broadly infect-ing multiple genera of animal hosts.In contrast,the small mammal genera Neodon,Dremomys,Ochotona,Anouro-sorex,and Mus were carrying individually specific rickettsial agents,indicating host tropism.There were 13 rickettsial species detected in 57.14%(8 out of 14)of tick species,with the highest prevalence(37.07%)observed in the genus Rhipicephalus.Eight rickettsial species were identified in 2375 livestock samples.Notably,six new Rickettsiales variants/strains were discovered,and Candidatus Rickettsia longicorni was unambiguously identified.Conclusions This large-scale survey provided further insight into the high genetic diversity and overall prevalence of emerging Rickettsiales within endemic hotspots in Yunnan Province.The potential threats posed by these emerging tick-borne Rickettsiales to public health warrant attention,underscoring the need for effective strategies to guide the prevention and control of emerging zoonotic diseases in China.展开更多
Drought resistance is required in rice breeding to address the challenge of frequent droughts . However, the evolutionary mechanism of rice drought resistance is not fully understood. We investigated the genetic diffe...Drought resistance is required in rice breeding to address the challenge of frequent droughts . However, the evolutionary mechanism of rice drought resistance is not fully understood. We investigated the genetic differentiation between upland and lowland rice domesticated in agro-ecosystems with contrasting water-soil conditions using genome-wide SNPs. We estimated morphological differences among upland and lowland rice in drought resistance and productivity through common garden experiments. Upland rice had better drought resistance but poorer productivity. The negative correlations between traits of drought resistance and productivity are attributed to the underlying genetic trade-offs through tight linkages (e.g., DCA1 and OsCesA7) or pleiotropic effects (e.g., LAX1). The genetic trade-offs are comm on and greatly shape the evolutio n of drought resista nee in upland rice . In genomic regions associated with both productivity and drought resistance, signs of balancing selection were detected in upland rice, while signs of directional selection were detected in lowland rice, potentially contributing to their adaptive differentiation. Signs of balancing selection in upland rice resulted from bi-directional selection during its domestication in drought-prone upland agro-ecosystems.Using genome-wide association analysis, we ide ntified several valuable quantitative trait loci associated with drought resista nee, for which highly differentiated genes should be considered candidates. Bi-directional selection breaking tight linkages by accumulating recombination events would be applicable in breeding water-saving and droughtresistance rice.展开更多
In this study,we propose an effective method for the fabrication of annulus micro-/nanostructures by a femtosecond laser doughnut beam.Compared with the traditional Bessel annulus beam shaping system,this method great...In this study,we propose an effective method for the fabrication of annulus micro-/nanostructures by a femtosecond laser doughnut beam.Compared with the traditional Bessel annulus beam shaping system,this method greatly compresses the light propagation path.It is theoretically and experimentally demonstrated that the obtained axial section of the peak envelope in the processing area is two waists of the isosceles triangle.By moving the relative position of the sample,annulus microstructures with different diameters on copper sheet could be fabricated.In addition,laser induced periodic surface structures with controllable direction are fabricated by this optical system.展开更多
Dear Editor,Ensuring food security with finite resources and environmental impacts is a new challenge in sustainable agriculture(Yu et al.,2022).It is therefore essential to develop suitable rice varieties for resourc...Dear Editor,Ensuring food security with finite resources and environmental impacts is a new challenge in sustainable agriculture(Yu et al.,2022).It is therefore essential to develop suitable rice varieties for resource-saving and environmentally friendly cultivation(Luo et al.,2019;Yu et al.,2022).Upland rice,which evolves many green characters for rice sustainable cultivation(e.g.,drought resistance,the usage efficiency of nitrate,the good capacity of direct seeding,etc.),is therefore an important germplasm in rice breeding(Luo et al.,2019).However,the origination and evolution of upland rice,as well as its green genetic resource,remain mysterious(Xia et al.,2019).展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFB1902700)the National Natural Science Foundation of China(No.11875129)+3 种基金the Fund of the State Key Laboratory of Intense Pulsed Radiation Simulation and Effect(No.SKLIPR1810)the Fund of Innovation Center of Radiation Application(No.KFZC2020020402)the Fund of the State Key Laboratory of Nuclear Physics and Technology,Peking University(No.NPT2020KFY08)the Joint Innovation Fund of China National Uranium Co.,Ltd.,State Key Laboratory of Nuclear Resources and Environment,East China University of Technology(No.2022NRE-LH-02).
文摘As a complement to X-ray computed tomography(CT),neutron tomography has been extensively used in nuclear engineer-ing,materials science,cultural heritage,and industrial applications.Reconstruction of the attenuation matrix for neutron tomography with a traditional analytical algorithm requires hundreds of projection views in the range of 0°to 180°and typically takes several hours to complete.Such a low time-resolved resolution degrades the quality of neutron imaging.Decreasing the number of projection acquisitions is an important approach to improve the time resolution of images;however,this requires efficient reconstruction algorithms.Therefore,sparse-view reconstruction algorithms in neutron tomography need to be investigated.In this study,we investigated the three-dimensional reconstruction algorithm for sparse-view neu-tron CT scans.To enhance the reconstructed image quality of neutron CT,we propose an algorithm that uses OS-SART to reconstruct images and a split Bregman to solve for the total variation(SBTV).A comparative analysis of the performances of each reconstruction algorithm was performed using simulated and actual experimental data.According to the analyzed results,OS-SART-SBTV is superior to the other algorithms in terms of denoising,suppressing artifacts,and preserving detailed structural information of images.
基金supported by the National Key Research and Development Program of China (No. 2022YFB1902700)the National Natural Science Foundation of China (No. 11875129)+3 种基金the Fund of the State Key Laboratory of Intense Pulsed Radiation Simulation and Effect (No. SKLIPR1810)Fund of Innovation Center of Radiation Application (No. KFZC2020020402)Fund of the State Key Laboratory of Nuclear Physics and Technology,Peking University (No. NPT2020KFY08)the Joint Innovation Fund of China National Uranium Co.,Ltd.,State Key Laboratory of Nuclear Resources and Environment,East China University of Technology (No. 2022NRE-LH-02)。
文摘The most critical part of a neutron computed tomography(NCT) system is the image processing algorithm,which directly affects the quality and speed of the reconstructed images.Various types of noise in the system can degrade the quality of the reconstructed images.Therefore,to improve the quality of the reconstructed images of NCT systems,efficient image processing algorithms must be used.The anisotropic diffusion filtering(ADF) algorithm can not only effectively suppress the noise in the projection data,but also preserve the image edge structure information by reducing the diffusion at the image edges.Therefore,we propose the application of the ADF algorithm for NCT image reconstruction.To compare the performance of different algorithms in NCT systems,we reconstructed images using the ordered subset simultaneous algebraic reconstruction technique(OS-SART) algorithm with different regular terms as image processing algorithms.In the iterative reconstruction,we selected two image processing algorithms,the Total Variation and split Bregman solved total variation algorithms,for comparison with the performance of the ADF algorithm.Additionally,the filtered back-projection algorithm was used for comparison with an iterative algorithm.By reconstructing the projection data of the numerical and clock models,we compared and analyzed the effects of each algorithm applied in the NCT system.Based on the reconstruction results,OS-SART-ADF outperformed the other algorithms in terms of denoising,preserving the edge structure,and suppressing artifacts.For example,when the 3D Shepp–Logan was reconstructed at 25 views,the root mean square error of OS-SART-ADF was the smallest among the four iterative algorithms,at only 0.0292.The universal quality index,mean structural similarity,and correlation coefficient of the reconstructed image were the largest among all algorithms,with values of 0.9877,0.9878,and 0.9887,respectively.
基金Project supported by the National Natural Science Foundation of China (Grant No.11903025)the starting fund of China West Normal University (Grant No.18Q062)+2 种基金the Sichuan Youth Science and Technology Innovation Research Team (Grant No.21CXTD0038)the Chongqing Science and Technology Bureau (Grant No.cstc2022ycjh-bgzxm0161)the Natural Science Foundation of Sichuan Province (Grant No.2022NSFSC1833)。
文摘We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),and ensure thatαis positive to avoid any singularity problems.The equation derived for the shadow radius indicates that it increases as the event horizon radius increases,making it an independent variable for determining BH temperature.By investigating the PT curve in relation to shadows,we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH PT.Furthermore,the results indicate that an increase in the parameterαcorresponds to a decrease in the temperature of the BH.By utilizing the relationship between the temperature and the shadow radius,it is possible to obtain the thermal profile of the Gauss-Bonnet AdS BH.It is evident that there is an N-type variation in temperature for pressures P<P_(c).Additionally,as the parameterαincreases,the region covered by shadow expands while the temperature decreases.The utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior.
基金supported by the National Key Research and Development Program of China(No.2022YFB1902700)the Joint Fund of Ministry of Education for Equipment Pre-research(No.8091B042203)+5 种基金the National Natural Science Foundation of China(No.11875129)the Fund of the State Key Laboratory of Intense Pulsed Radiation Simulation and Effect(No.SKLIPR1810)the Fund of Innovation Center of Radiation Application(No.KFZC2020020402)the Fund of the State Key Laboratory of Nuclear Physics and Technology,Peking University(No.NPT2023KFY06)the Joint Innovation Fund of China National Uranium Co.,Ltd.,State Key Laboratory of Nuclear Resources and Environment,East China University of Technology(No.2022NRE-LH-02)the Fundamental Research Funds for the Central Universities(No.2023JG001).
文摘Neutron computed tomography(NCT)is widely used as a noninvasive measurement technique in nuclear engineering,thermal hydraulics,and cultural heritage.The neutron source intensity of NCT is usually low and the scan time is long,resulting in a projection image containing severe noise.To reduce the scanning time and increase the image reconstruction quality,an effective reconstruction algorithm must be selected.In CT image reconstruction,the reconstruction algorithms can be divided into three categories:analytical algorithms,iterative algorithms,and deep learning.Because the analytical algorithm requires complete projection data,it is not suitable for reconstruction in harsh environments,such as strong radia-tion,high temperature,and high pressure.Deep learning requires large amounts of data and complex models,which cannot be easily deployed,as well as has a high computational complexity and poor interpretability.Therefore,this paper proposes the OS-SART-PDTV iterative algorithm,which uses the ordered subset simultaneous algebraic reconstruction technique(OS-SART)algorithm to reconstruct the image and the first-order primal–dual algorithm to solve the total variation(PDTV),for sparse-view NCT three-dimensional reconstruction.The novel algorithm was compared with other algorithms(FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV)by simulating the experimental data and actual neutron projection experiments.The reconstruction results demonstrate that the proposed algorithm outperforms the FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV algorithms in terms of preserving edge structure,denoising,and suppressing artifacts.
文摘Objective To retrospectively identify risk factors and the prognosis for new-onset atrial fibrillation (AF)after implantation of dual-chamber pacemakers in elderly patients.Methods Consecutive patients aged >65years who underwent their first implantation of a dual-chamber permanent pacemaker in Beijing Anzhen Hospital from October 2013to May 2016were enrolled.Their complete program- ming and follow-up data were recorded.Follow-up end points included new-onset AF and major adverse cardiovascular and cerebrovascular events.Restdts Altogether,322patients were enrolled,with new-onset AF observed in 79(24.5%)during their follow-up.Multivariable analysis identified four independent predictors of new-onset AF in elderly patients after pacemaker implantation:hypertension (HR =3.040, 95%CI:1.09-3.05,P =0.00),age (HR =1.966,95%CI:1.57-3.68,P =0.01);left atrial enlargement (HR =1.645,95%CI:1.05-1.25,P = 0.03);high ventricular pacing rate (HR =1.137,95%CI:1.01-1.06,P =0.01).Univariable analysis indicated that the CHA2DS2-VASc score was also a risk factor for AF (HR =1.368,95%CI:1.178-1.589,P =0.002),whereas multivariable regression analysis did not. Kaplan-Meier survival analysis showed that the risk for ischemic stroke was significantly higher in the new-onset AF group than in the non-AF group (P <0.05).Conclusion Hypertension,age,left atrial enlargement,and high ventricular pacing rate were independent predictors of new-onset AF in elderly patients after implantation of a permanent pacemaker.New-onset AF increased the risk for ischemic stroke.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574122 and 11704167)the Fundamental Research Funds for the Central Universities,China(Grant Nos.lzujbky-2017-k20 and lzujbky-2017-31)
文摘The oriented(CoIr)_(100-x)P_x(P = B, Ni, and SiO_2) soft magnetic films are prepared. Their morphology is measured using transmission electron microscopy(TEM), and reveals that these films exhibit good crystallinity and high degree of the c-axis orientation. The magnetic properties are thoroughly investigated as a function of doping x. Our results show that all of these films possess negative magnetocrystalline anisotropy as required by possible applications. Both the intrinsic and extrinsic contributions are considered to interpret the broadening of the ferromagnetic resonance spectral linewidth. The intrinsic Gilbert damping is identified as the main cause of the linewidth broadening, while the extrinsic part originating from inhomogeneities only plays a minor role. More interestingly, our results show that the damping constant can be controlled by using the doping method.
基金supported by the National Key R&D Program of China(No.2020YFA0711003)the National Natural Science Foundation of China(No.51925506),and the XPLORER PRIZE.
文摘1-(4-ethylphenyl)-nonane-1,3-dione(0206)is an oil-soluble liquid molecule with rod-like structure.In this study,the chelate(0206-Fe)with octahedral structure was prepared by the reaction of ferric chloride and 1,3-diketone.The experimental results show that when using 0206 and a mixed solution containing 60%0206-Fe and 40%0206(0206-Fe(60%))as lubricants of the steel friction pairs,superlubricity can be achieved(0.007,0.006).But their wear scar diameters(WSD)were very large(532µm,370µm),which resulted in the pressure of only 44.3 and 61.8 MPa in the contact areas of the friction pairs.When 0206-Fe(60%)was mixed with PAO6,it was found that the friction coefficient(COF)decreased with increase of 0206-Fe(60%)in the solution.When the ratio of 0206-Fe(60%)to PAO6 was 8:2(PAO6(20%)),it exhibited better comprehensive tribological properties(232.3 MPa).Subsequent studies have shown that reducing the viscosity of the base oil in the mixed solution helped to reduce COF and increased WSD.Considering the COF,contact pressure,and running-in time,it was found that the mixed lubricant(Oil3(20%))prepared by the base oil with a viscosity of 19.7 mPa·s(Oil3)and 0206-Fe(60%)exhibited the best tribological properties(0.007,161.4 MPa,3,100 s).
基金Supported by the National Natural Science Foundation of China(11903025)the Science and Technology Program of Sichuan Province,China(2023ZYD0023)the starting fund of China West Normal University(18Q062)。
文摘In this work,the optical appearance of an asymmetric thin-shell wormhole with a Bardeen profile is studied.To initiate the process,we need to construct an asymmetric thin-shell wormhole utilizing the cut-and-paste technique proposed by Visser and subsequently ascertain its pertinent physical quantities such as the radius of the photon sphere and critical impact parameters for different values of magnetic charge g.Then,the effective potential and motion behavior of photons are also investigated within the framework of asymmetric thin-shell wormholes with a Bardeen profile.It can be found that the effective potential,ray trajectory,and azimuthal angle of the thin-shell wormhole exhibit a strong correlation with the mass ratio of black holes.By considering the accretion disk as the sole background light source,we observe additional photon rings and lensing bands in the optical appearance of the asymmetric thin-shell wormhole with a Bardeen profile compared to those exhibited by the Bardeen black hole.One can find that there is an increase in the size of the specific additional light bands with increasing magnetic charge g,which is different from the black hole case.These exceptionally luminous rings can serve as a robust criterion for the identification and characterization of the thin-shell wormhole spacetime.
文摘In this paper,we study the optical properties of asymmetric thin-shell wormholes(ATWs)under torsion charge.Utilizing the cut-and-paste method developed by Visser,we construct these wormholes and determine their key physical properties,such as the radius of the photon sphere and critical impact parameters,under different torsion charges.Furthermore,we investigate the effective potential and behavior of photon motion within the wormhole spacetime,identifying a relationship between photon trajectories and impact parameters.The study focuses on scenarios where thin accretion disks act as the primary light source.It reveals that the optical features of ATWs under torsion charge significantly differ from those of black holes(BHs).Notably,an increase in torsion charge leads to a reduction in the sizes of both extra photon rings and lensing bands,which serve as important markers for distinguishing and characterizing ATW spacetimes from those of BHs.
基金Supported by the National Natural Science Foundation of China(12047564)the Fundamental Research Funds for the Central Universities(2021CDJZYJH-003)the Postdoctoral Science Foundation of Chongqing(cstc2021jcyj-bsh0124)。
文摘In this paper,the phase structure of the Hayward-anti-de Sitter(AdS)black hole(BH)is studied using shadow formalism.It has been found that the shadow radius is a monotonic function of the horizon radius and can therefore play an equivalent role to the horizon radius in characterizing the thermodynamics of the Hayward-AdS BH.The thermodynamic phase transition(PT)of the Hayward-AdS BH is investigated with the shadow radius.It is shown that as the magnetic charge increases,the shadow radius becomes larger,while the coexistence temperature becomes lower.The thermal profile of the Hayward-AdS BH is established by combining the temperature diagram and the shadow cast diagram,which shows that for a fixed magnetic charge,the temperature of the Hayward-AdS BH increases with the pressure whereas the region of the thermal profile decreases with the pressure.In particular,the temperature of the Hayward-AdS BH follows an N-type change trend when it is smaller than the critical temperature.It implies that the BH shadow may be used to investigate the thermodynamics of the Hayward-AdS BH.
基金financial support(Sinergia No.177178 and research project No.315230_197644/1)financial support from the Swiss National Science Foundation(No.190345,188522 and 206501)financial support from China Scholarship Council(CSC,No.202006790027).
文摘Digital light processing(DLP)of structurally complex poly(ethylene glycol)(PEG)hydrogels with high mechanical toughness represents a long-standing challenge in thefield of 3D printing.Here,we report a 3D printing approach for the high-resolution manufacturing of structurally complex and mechanically strong PEG hydrogels via heat-assisted DLP.Instead of using aqueous solutions of photo-crosslinkable monomers,PEG macromonomer melts werefirst printed in the absence of water,resulting in bulk PEG networks.Then,post-printing swelling of the printed networks was achieved in water,producing high-fidelity 3D hydrogels with complex structures.By employing a dual-macromonomer resin containing a PEG-based four-arm macrophotoinitiator,“all-PEG”hydrogel constructs were pro-duced with compressive toughness up to 1.3 MJ m^(-3).By this approach,porous 3D hydrogel scaffolds with trabecular-like architecture were fabricated,and the scaf-fold surface supported cell attachment and the formation of a monolayer mimicking bone-lining cells.This study highlights the promises of heat-assisted DLP of PEG photopolymers for hydrogel fabrication,which may accelerate the development of 3D tissue-like constructs for regenerative medicine.
基金supported by grants from the National Natural Science Foundation of China(Nos.81902063,81871639,and 92169109)Ministry of Science and Technology of the People’s Republic of China(Nos.2018YFA0507100 and 2020YFA0707500)+7 种基金supported by the Chongqing Science and Technology Commission(No.cstc2019jcyj-msxmX0135)Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJQN202000442)CQMU Chongqing Medical University(No.W0073)W.W.,and grants from Lingang Laboratory(No.LG202101-01-07)Science and Technology Commission of Shanghai Municipality(Nos.YDZX20213100001556 and 20XD1422900)Natural Science Foundation of Tianjin(No.18JCJQJC48000)Shanghai Municipal Development&Reform Commission Major Project(No.ZD2021CY001)further supported by Shanghai Frontiers Science Center for Biomacromolecules and Precision Medicine,ShanghaiTech University.
文摘Dear Editor,Since its appearance in May 2022,monkeypox has spread to>100 countries and afflicted tens of thousands of people.Individuals infected with monkeypox present a fever,an extensive characteristic rash,and usually swollen lymph nodes(Chatterjee et al.,2022).The number of confirmed cases worldwide continues to grow at a rapid rate,but the treatment to this highly infectious viral disease is still very limited.Identification of new targeted-therapies will be crucial to control of this emerging public health threat.
文摘Background Rickettsia and related diseases have been identified as significant global public health threats.This study involved comprehensive field and systematic investigations of various rickettsial organisms in Yunnan Province.Methods Between May 18,2011 and November 23,2020,field investigations were conducted across 42 counties in Yunnan Province,China,encompassing small mammals,livestock,and ticks.Preliminary screenings for Rickettsiales involved amplifying the 16S rRNA genes,along with additional genus-or species-specific genes,which were subse-quently confrmed through sequencing results.Sequence comparisons were carried out using the Basic Local Align-ment Search Tool(BLAST).Phylogenetic relationships were analyzed using the default parameters in the Molecular Evolutionary Genetics Analysis(MEGA)program.The chi-squared test was used to assess the diversities and compo-nent ratios of rickettsial agents across various parameters.Results A total of 7964 samples were collected from small mammals,livestock,and ticks through Yunnan Province and submitted for screening for rickettsial organisms.Sixteen rickettsial species from the genera Rickettsia,Anaplasma,Ehrlichia,Neoehrlichia,and Wolbachia were detected,with an overall prevalence of 14.72%.Among these,11 species were identifed as pathogens or potential pathogens to humans and livestock.Specifically,10 rickettsial organisms were widely found in 42.11%(24 out of 57)of small mammal species.High prevalence was observed in Dremomys samples at 5.60%,in samples from regions with latitudes above 4000 m or alpine meadows,and in those obtained from Yuanmou County.Anaplasma phagocytophilum and Candidatus Neoehrlichia mikurensis were broadly infect-ing multiple genera of animal hosts.In contrast,the small mammal genera Neodon,Dremomys,Ochotona,Anouro-sorex,and Mus were carrying individually specific rickettsial agents,indicating host tropism.There were 13 rickettsial species detected in 57.14%(8 out of 14)of tick species,with the highest prevalence(37.07%)observed in the genus Rhipicephalus.Eight rickettsial species were identified in 2375 livestock samples.Notably,six new Rickettsiales variants/strains were discovered,and Candidatus Rickettsia longicorni was unambiguously identified.Conclusions This large-scale survey provided further insight into the high genetic diversity and overall prevalence of emerging Rickettsiales within endemic hotspots in Yunnan Province.The potential threats posed by these emerging tick-borne Rickettsiales to public health warrant attention,underscoring the need for effective strategies to guide the prevention and control of emerging zoonotic diseases in China.
基金the National Key R&D Programe of China (grant no. 2017YFD0300100)Shanghai Agriculture Applied Technology Development Program, China (grant no. G2016060107)+4 种基金Shanghai Natural Science Foundation (17ZR1425500)National High-Tech Research and Development Program of China (863 Plan (grant no.2014AA10A603)Shan ghai Agriculture Applied Tech no logy Developme nt Program, China (grant no. 2017-02-08-00-08-F00071)National Natural Science Foundation of China (grant no. 31501270)Shared Platform of Crop Germplasm Resources in Shanghai (18DZ2293700).
文摘Drought resistance is required in rice breeding to address the challenge of frequent droughts . However, the evolutionary mechanism of rice drought resistance is not fully understood. We investigated the genetic differentiation between upland and lowland rice domesticated in agro-ecosystems with contrasting water-soil conditions using genome-wide SNPs. We estimated morphological differences among upland and lowland rice in drought resistance and productivity through common garden experiments. Upland rice had better drought resistance but poorer productivity. The negative correlations between traits of drought resistance and productivity are attributed to the underlying genetic trade-offs through tight linkages (e.g., DCA1 and OsCesA7) or pleiotropic effects (e.g., LAX1). The genetic trade-offs are comm on and greatly shape the evolutio n of drought resista nee in upland rice . In genomic regions associated with both productivity and drought resistance, signs of balancing selection were detected in upland rice, while signs of directional selection were detected in lowland rice, potentially contributing to their adaptive differentiation. Signs of balancing selection in upland rice resulted from bi-directional selection during its domestication in drought-prone upland agro-ecosystems.Using genome-wide association analysis, we ide ntified several valuable quantitative trait loci associated with drought resista nee, for which highly differentiated genes should be considered candidates. Bi-directional selection breaking tight linkages by accumulating recombination events would be applicable in breeding water-saving and droughtresistance rice.
基金This work was supported by the National Natural Science Foundation of China(No.51975595)the Joint Funds of Ministry of Education of China(No.6141A02022130).
文摘In this study,we propose an effective method for the fabrication of annulus micro-/nanostructures by a femtosecond laser doughnut beam.Compared with the traditional Bessel annulus beam shaping system,this method greatly compresses the light propagation path.It is theoretically and experimentally demonstrated that the obtained axial section of the peak envelope in the processing area is two waists of the isosceles triangle.By moving the relative position of the sample,annulus microstructures with different diameters on copper sheet could be fabricated.In addition,laser induced periodic surface structures with controllable direction are fabricated by this optical system.
基金the Earmarked Fund of CARS(CARS-01)Shanghai Natural ScienceFoundation(20ZR1449300)+2 种基金Shanghai Agriculture Applied Technology Development Program,China(Grant No.G2016060107)Shared Platform of Crop Germplasm Resources in Shanghai(18DZ2293700)Platform for National Crop Germplasm Resources(Shanghai)(NICGR2021-2).
文摘Dear Editor,Ensuring food security with finite resources and environmental impacts is a new challenge in sustainable agriculture(Yu et al.,2022).It is therefore essential to develop suitable rice varieties for resource-saving and environmentally friendly cultivation(Luo et al.,2019;Yu et al.,2022).Upland rice,which evolves many green characters for rice sustainable cultivation(e.g.,drought resistance,the usage efficiency of nitrate,the good capacity of direct seeding,etc.),is therefore an important germplasm in rice breeding(Luo et al.,2019).However,the origination and evolution of upland rice,as well as its green genetic resource,remain mysterious(Xia et al.,2019).
