Background: 4D-CT has been used to localize the parathyroid adenomas and hyperplasia since 2006 as a second line study after TC-99 m MIBI and ultrasonography. However, multiple studies have shown that 4D-CT is a robus...Background: 4D-CT has been used to localize the parathyroid adenomas and hyperplasia since 2006 as a second line study after TC-99 m MIBI and ultrasonography. However, multiple studies have shown that 4D-CT is a robust imaging method with high diagnostic accuracy, becoming increasingly popular among surgeons and radiologists. Purpose: To assess the diagnostic performance of 4D-CT scans to identify the pathologic gland(s), using pathology and intraoperative findings as gold standards. Methods: We analyzed patients with primary and secondary hyperparathyroidism who had intraoperative reports, pathology, parathyroid hormone levels, and preoperative 4D-CT. Histology, surgical findings, and decreased parathyroid hormone levels were used as gold standards. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy and 95% confidence interval were calculated. Fleiss’ kappa was used to assess the inter-observer agreement. Results: Sixty-seven patients were included. Sixty-two patients had a single adenoma, and five patients had a multiple gland disease (adenomas or hyperplasia). A total of 72 glands were proven to have parathyroid adenomas or hyperplasia. The sensitivity, specificity, PPV, NPV and accuracy are 85%, 97%, 96%, 87% and 91% for lateralization and 76%, 96%, 85%, 92% and 90% for quadrant localization, respectively in single-gland disease. The sensitivity, specificity, PPV, NPV and accuracy are 88%, 100%, 100%, 50% and 90% for lateralization and 71%, 100%, 100%, 60% and 80% for quadrant localization respectively in multiple-gland disease. Fleiss’ kappa value is 5.6 (moderate inter-observer agreement). Conclusion: 4D-CT is a robust method in the localization of hyperfunctioning parathyroid glands with high accuracy and at least moderate inter-observer agreement.展开更多
In this paper, we mainly investigate the realization of 3-Lie algebras from a family of Lie algebras. We prove the realization theorem, offer a concrete example realizing all type of 4-dimensional 3-Lie algebras, and ...In this paper, we mainly investigate the realization of 3-Lie algebras from a family of Lie algebras. We prove the realization theorem, offer a concrete example realizing all type of 4-dimensional 3-Lie algebras, and also give some properties about semi-simple n-Lie algebras.展开更多
When discovering the potential of canards flying in 4-dimensional slow-fast system with a bifurcation parameter, the key notion “symmetry” plays an important role. It is of one parameter on slow vector field. Then, ...When discovering the potential of canards flying in 4-dimensional slow-fast system with a bifurcation parameter, the key notion “symmetry” plays an important role. It is of one parameter on slow vector field. Then, it should be determined to introduce parameters to all slow/fast vectors. It is, however, there might be no way to explore for another potential in this system, because the geometrical structure is quite different from the system with one parameter. Even in this system, the “symmetry” is also useful to obtain the potentials classified by R. Thom. In this paper, via the coordinates changing, the possible way to explore for the potential will be shown. As it is analyzed on “hyper finite time line”, or done by using “non-standard analysis”, it is called “Hyper Catastrophe”. In the slow-fast system which includes a very small parameter , it is difficult to do precise analysis. Thus, it is useful to get the orbits as a singular limit. When trying to do simulations, it is also faced with difficulty due to singularity. Using very small time intervals corresponding small , we shall overcome the difficulty, because the difference equation on the small time interval adopts the standard differential equation. These small intervals are defined on hyper finite number N, which is nonstandard. As and the intervals are linked to use 1/N, the simulation should be done exactly.展开更多
Initiation, growth, and rupture of cerebral aneurysms are caused by hemodynamic factors. It is extensively accepted that the cerebral aneurysm wall is assumed to be rigid using computational fluid dynamics (CFD). Furt...Initiation, growth, and rupture of cerebral aneurysms are caused by hemodynamic factors. It is extensively accepted that the cerebral aneurysm wall is assumed to be rigid using computational fluid dynamics (CFD). Furthermore, fluid-structure interactions have been recently applied for simulation of an elastic cerebral aneurysm model. Herein, we examined cerebral aneurysm hemodynamics in a realistic moving boundary deformation model based on 4-dimensional computed tomographic angiography (4D-CTA) obtained by high time-resolution using numerical simulation. The aneurysm of the realistic moving deformation model based on 4D-CTA at each phase was constructed. The effect of small wall deformation on hemodynamic characteristics might be interested. So, four hemodynamic factors (wall shear stress, wall shear stress divergence, oscillatory shear index and residual residence time) were determined from the numerical simulation, and their behaviors were assessed in the basilar bifurcation aneurysm.展开更多
With the aid of a global barotropic model, the role of the interaction of the synoptic-scale disturbance and the planetary flow in block onset is examined by a 4-dimensional variational approach. A cost function is de...With the aid of a global barotropic model, the role of the interaction of the synoptic-scale disturbance and the planetary flow in block onset is examined by a 4-dimensional variational approach. A cost function is defined to measure the squared errors of the forecasted stream functions during block onset period (day 4 and day 5 in this study) over a selected blocking domain. The sensitivity of block onset with respect to the initial synoptic-scale disturbance is studied by examining the gradient of the defined cost function with respect to the initial (during the first 24 hours) vorticity forcing, which is evaluated by the adjoint integration. Furthermore, the calculated cost function and gradient are connected with the limited-memory quasi-Newton optimization algorithm for solving the optimal initial vorticity forcing for block onset. For two studied cases of block onset (northern Atlantic and northern Pacific) introducing the optimal initial vorticity forcing, the nonlinear barotropic advection process mostly reconstructs these blocking onset processes. The results show that the formation of blocking can be correctly described by a barotropic nonlinear advection process, in which the wave- (synoptic-scale) flow (planetary-scale) interaction plays a very important role. On an appropriate planetary-scale flow, a certain synoptic-scale disturbance can cause the blocking onset by the interaction between the synoptic scale perturbations and the planetary scale basic flows. The extended forecasts show that the introduction of the optimal initial vorticity forcing can predict the blocking process up to the 7th or 8th day in this simple model case. The experimental results in this study show that the 4-dimensional variational approach has a good potential to be applied to study the dynamics of the medium-range weather processes. This simple model case study is only an initial trial. Applying the framework in this study to a complex model will further our understanding of the mechanism of the atmospheric/oceanic processes and improve their prediction.展开更多
In this article,by employing the Hirota bilinear approach and the long wave limit method,we not only derive soliton solutions,lump solutions,and hybrid solutions for the(2+1)-dimensional Yu-Toda-Sasa-Fukuyama(YTSF)equ...In this article,by employing the Hirota bilinear approach and the long wave limit method,we not only derive soliton solutions,lump solutions,and hybrid solutions for the(2+1)-dimensional Yu-Toda-Sasa-Fukuyama(YTSF)equation,but also analyze the dynamical behaviors of nonlinear local wave propagation in shallow water.Firstly,based on the Hirota bilinear approach,one to four-order soliton solutions of the YTSF equation are obtained,and the effects of different parameters on the amplitude,propagation trajectory,and displacement of solitons are investigated.Secondly,using the long wave limit approach,one to three-order lump solutions and various physical quantities of the YTSF equation are derived.It is found that the real and imaginary parts of the parameter pi dominate the propagation trajectory and the shape of lump waves,respectively.Furthermore,we construct the hybrid solution for the YTSF equation,leading to the conclusion that the interaction between lumps and solitons constitutes an elastic collision.To intuitively understand the dynamic behaviors of these solutions,we conduct numerical simulations to present vivid three-dimensional visualizations.展开更多
Recently,Greenfeld and Tao(2024)disproved the conjecture that translational tilings of a single tile can always be periodic.In another paper(Greenfeld and Tao(2025)),they also showed that if the dimension n is part of...Recently,Greenfeld and Tao(2024)disproved the conjecture that translational tilings of a single tile can always be periodic.In another paper(Greenfeld and Tao(2025)),they also showed that if the dimension n is part of the input,the translational tiling for subsets of Z^(n) with one tile is undecidable.These two results are very strong pieces of evidence for the conjecture that translational tiling of Z^(n) with a monotile is undecidable for some fixed n.In this paper,we show that translational tiling of the 3-dimensional space with a set of 5 polycubes is undecidable.By introducing a technique that lifts a set of polycubes and its tiling from the 3-dimensional space to the 4-dimensional space,we manage to show that translational tiling of the 4-dimensional space with a set of 4 tiles is undecidable.This is a step towards the attempt to settle the conjecture of the undecidability of translational tiling of the n-dimensional space with a monotile for some fixed n.展开更多
The clinical adaptation of 4D-MRI in respiratory motion management is limited by the low image quality and motion artifacts of 4D-MRI sequences.This study aims to develop a novel artifact Map-guided Nonlocal mean(AM-N...The clinical adaptation of 4D-MRI in respiratory motion management is limited by the low image quality and motion artifacts of 4D-MRI sequences.This study aims to develop a novel artifact Map-guided Nonlocal mean(AM-NLM)technique that can be integrated into the clinical 4D-MRI workflow to suppress motion artifacts and enhance image quality.The AM-NLM technique was developed and tested on 4D-MR images of 28 liver cancer patients.A multiphase motion field was computed on the frames with the minimum average localized gradient entropy for each phase to generate a full set of improved quality 4D-MR images.Artifact maps were calculated based on the local image sharpness to guide nonlocal averaging,and a set of denoised eight-phase 4D-MR images was finally generated.The 4D-MR images were evaluated for image quality and motion accuracy.Conventional 4D-MRI approaches were also evaluated for comparison.AM-NLM 4D-MR images have significant improvements in SNR and CNR compared to the original 4D-MR images.High motion accuracy was achieved for AM-NLM 4D-MR images because the average deviation in the diaphragm position from the mean value for each phase was at the subvoxel level.Both qualitative and quantitative results suggested that the 4D-MR images generated by the AM-NLM technique had high image quality while maintaining image sharpness and motion accuracy.The AM-NLM technique has shown capability of suppressing motion artifacts and enhancing image quality of clinically acquired 4D-MR images,making it a promising technique in applications of 4D-MRI in radiotherapy.展开更多
Ordered NiCo_(2)O_(4)/rGO nanowire arrays(NWAs)grown on a Ni foam substrate were synthesized using a template-free hydrothermal method and employed as an electrode with outstanding electrochemical properties for super...Ordered NiCo_(2)O_(4)/rGO nanowire arrays(NWAs)grown on a Ni foam substrate were synthesized using a template-free hydrothermal method and employed as an electrode with outstanding electrochemical properties for supercapacitors.After conducting a series of time-variable controlled experiments,the structure,morphology,and electrochemical properties of NiCo_(2)O_(4)/rGO NWAs were analyzed to find the most suitable growth time.Benefited from such unique array architectures,the designed NiCo_(2)O_(4)/rGO NWAs electrode demonstrates significant electrochemical properties,showing a specific capacitance of 2418 F·g^(-1)at a charge-discharge current density of 1 A·g^(-1).Moreover,it demonstrates exceptional stability,maintaining a capacity retention of 81.5%after undergoing 2,000 cycles,even when subjected to a current density of 10 A·g^(-1).The reason of high stability is that the spacing between the nanowire arrays is large and the diffusion resistance of the electrolyte is significantly reduced,which facilitates the diffusion of the electrolyte into the interior of the electrodes and establishes an effective contact with the surface of the nanowires.Furthermore,the NiCo_(2)O_(4)/rGO nanowire array grows directly on the Ni foam without binder,which establishes rapid electron transport pathways on the Ni foam substrate,resulting in excellent electrochemical properties.展开更多
Recent advances in bone regeneration have introduced the concept of four-dimensional(4D)scaffolds that can undergo morphological and functional changes in response to external stimuli.While several studies have propos...Recent advances in bone regeneration have introduced the concept of four-dimensional(4D)scaffolds that can undergo morphological and functional changes in response to external stimuli.While several studies have proposed patient-specific designs for defect sites,they often fail to adequately distinguish the advantages of 4D scaffolds over conventional 3D counterparts.This study aimed to investigate the potential benefits of 4D scaffolds in clinically challenging scenarios involving curved defects,where fixation is difficult.We proposed the use of Shape-Memory Polymers(SMPs)as a solution to address critical issues in personalized scaffold fabrication,including dimensional accuracy,measurement error,and manufacturing imprecision.Experimental results demonstrated that the Curved-Layer Fused Deposition Modeling(CLFDM)scaffold,which offers superior conformability to curved defects,achieved significantly higher interfacial contact with the defect area compared to traditional Fused Deposition Modeling(FDM)scaffolds.Specifically,the CLFDM scaffold facilitated bone regeneration of 25.59±4.72 mm^(3),which is more than twice the 9.37±1.36 mm^(3)observed with the 3D FDM scaffold.Furthermore,the 4D CLFDM scaffold achieved 75.38±11.65 mm^(3)of new bone formation after four weeks,approximately three times greater than that of the 3D CLFDM scaffold,regardless of surface micro-roughness.These results underscore that improved geometrical conformity between the scaffold and the defect site enhances cellular infiltration and contributes to more effective bone regeneration.The findings also highlight the promise of 4D scaffolds as a compelling strategy to overcome geometric and dimensional mismatches in the design of patient-specific scaffolds.展开更多
The accumulation of heavy metals in mushrooms has presented a significant risk to human health,underscoring the importance of devising a portable and cost-effective method for detecting heavy metals.Thus,we have devel...The accumulation of heavy metals in mushrooms has presented a significant risk to human health,underscoring the importance of devising a portable and cost-effective method for detecting heavy metals.Thus,we have developed an electrochemical sensor based on 3-dimensional highly reduced graphene oxide(3D-HRGO)in conjunction with Fe_(3)O_(4)nanoparticles,enabling the simultaneous quantification of Cd^(2+),Pb^(2+),Cu^(2+),and Hg^(2+).The 3D-HRGO/Fe_(3)O_(4)nano-particles material prepared in this study was characterized and confirmed by multiple techniques,then dispersed in a simple and environmental dispersant,consist of 75%ethanol and 0.1%Nafion,and coating on a glass carbon electrode(GCE)to preparing a 3D-HRGO/Fe_(3)O_(4)/GCE sensor.The limit of detection(LOD)of 3D-HRGO/Fe_(3)O_(4)/GCE sensor for Cd^(2+),Pb^(2+),Cu^(2+),and Hg^(2+)in simultaneous detection were 0.2,0.6,0.6,and 0.9μg/L,respectively.The sensor demonstrates exceptional stability,reproducibility,anti-interference,and recovery rate.Furthermore,the electrochemical sensor was employed to detect heavy metals in actual mushrooms and validated through conventional methodologies.This study represents the pioneering utilization of 3D-HRGO/Fe_(3)O_(4)as a foundational material for an electrochemical sensor capable of simultaneous detection of multiple metals,thereby advancing the progress of on-site and expeditious detection techniques.展开更多
We show that if the fiber of a closed 4-dimensional mapping torus X is reducible and not S2× S1 or RP3#P3, then the virtual first Betti number of X is infinite and X is not virtually symplectic. This confirms two...We show that if the fiber of a closed 4-dimensional mapping torus X is reducible and not S2× S1 or RP3#P3, then the virtual first Betti number of X is infinite and X is not virtually symplectic. This confirms two conjectures made by Li and Ni （2014） in an earlier paper.展开更多
文摘Background: 4D-CT has been used to localize the parathyroid adenomas and hyperplasia since 2006 as a second line study after TC-99 m MIBI and ultrasonography. However, multiple studies have shown that 4D-CT is a robust imaging method with high diagnostic accuracy, becoming increasingly popular among surgeons and radiologists. Purpose: To assess the diagnostic performance of 4D-CT scans to identify the pathologic gland(s), using pathology and intraoperative findings as gold standards. Methods: We analyzed patients with primary and secondary hyperparathyroidism who had intraoperative reports, pathology, parathyroid hormone levels, and preoperative 4D-CT. Histology, surgical findings, and decreased parathyroid hormone levels were used as gold standards. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy and 95% confidence interval were calculated. Fleiss’ kappa was used to assess the inter-observer agreement. Results: Sixty-seven patients were included. Sixty-two patients had a single adenoma, and five patients had a multiple gland disease (adenomas or hyperplasia). A total of 72 glands were proven to have parathyroid adenomas or hyperplasia. The sensitivity, specificity, PPV, NPV and accuracy are 85%, 97%, 96%, 87% and 91% for lateralization and 76%, 96%, 85%, 92% and 90% for quadrant localization, respectively in single-gland disease. The sensitivity, specificity, PPV, NPV and accuracy are 88%, 100%, 100%, 50% and 90% for lateralization and 71%, 100%, 100%, 60% and 80% for quadrant localization respectively in multiple-gland disease. Fleiss’ kappa value is 5.6 (moderate inter-observer agreement). Conclusion: 4D-CT is a robust method in the localization of hyperfunctioning parathyroid glands with high accuracy and at least moderate inter-observer agreement.
文摘In this paper, we mainly investigate the realization of 3-Lie algebras from a family of Lie algebras. We prove the realization theorem, offer a concrete example realizing all type of 4-dimensional 3-Lie algebras, and also give some properties about semi-simple n-Lie algebras.
文摘When discovering the potential of canards flying in 4-dimensional slow-fast system with a bifurcation parameter, the key notion “symmetry” plays an important role. It is of one parameter on slow vector field. Then, it should be determined to introduce parameters to all slow/fast vectors. It is, however, there might be no way to explore for another potential in this system, because the geometrical structure is quite different from the system with one parameter. Even in this system, the “symmetry” is also useful to obtain the potentials classified by R. Thom. In this paper, via the coordinates changing, the possible way to explore for the potential will be shown. As it is analyzed on “hyper finite time line”, or done by using “non-standard analysis”, it is called “Hyper Catastrophe”. In the slow-fast system which includes a very small parameter , it is difficult to do precise analysis. Thus, it is useful to get the orbits as a singular limit. When trying to do simulations, it is also faced with difficulty due to singularity. Using very small time intervals corresponding small , we shall overcome the difficulty, because the difference equation on the small time interval adopts the standard differential equation. These small intervals are defined on hyper finite number N, which is nonstandard. As and the intervals are linked to use 1/N, the simulation should be done exactly.
文摘Initiation, growth, and rupture of cerebral aneurysms are caused by hemodynamic factors. It is extensively accepted that the cerebral aneurysm wall is assumed to be rigid using computational fluid dynamics (CFD). Furthermore, fluid-structure interactions have been recently applied for simulation of an elastic cerebral aneurysm model. Herein, we examined cerebral aneurysm hemodynamics in a realistic moving boundary deformation model based on 4-dimensional computed tomographic angiography (4D-CTA) obtained by high time-resolution using numerical simulation. The aneurysm of the realistic moving deformation model based on 4D-CTA at each phase was constructed. The effect of small wall deformation on hemodynamic characteristics might be interested. So, four hemodynamic factors (wall shear stress, wall shear stress divergence, oscillatory shear index and residual residence time) were determined from the numerical simulation, and their behaviors were assessed in the basilar bifurcation aneurysm.
文摘With the aid of a global barotropic model, the role of the interaction of the synoptic-scale disturbance and the planetary flow in block onset is examined by a 4-dimensional variational approach. A cost function is defined to measure the squared errors of the forecasted stream functions during block onset period (day 4 and day 5 in this study) over a selected blocking domain. The sensitivity of block onset with respect to the initial synoptic-scale disturbance is studied by examining the gradient of the defined cost function with respect to the initial (during the first 24 hours) vorticity forcing, which is evaluated by the adjoint integration. Furthermore, the calculated cost function and gradient are connected with the limited-memory quasi-Newton optimization algorithm for solving the optimal initial vorticity forcing for block onset. For two studied cases of block onset (northern Atlantic and northern Pacific) introducing the optimal initial vorticity forcing, the nonlinear barotropic advection process mostly reconstructs these blocking onset processes. The results show that the formation of blocking can be correctly described by a barotropic nonlinear advection process, in which the wave- (synoptic-scale) flow (planetary-scale) interaction plays a very important role. On an appropriate planetary-scale flow, a certain synoptic-scale disturbance can cause the blocking onset by the interaction between the synoptic scale perturbations and the planetary scale basic flows. The extended forecasts show that the introduction of the optimal initial vorticity forcing can predict the blocking process up to the 7th or 8th day in this simple model case. The experimental results in this study show that the 4-dimensional variational approach has a good potential to be applied to study the dynamics of the medium-range weather processes. This simple model case study is only an initial trial. Applying the framework in this study to a complex model will further our understanding of the mechanism of the atmospheric/oceanic processes and improve their prediction.
基金Supported by the National Natural Science Foundation of China(12001424,12271324)the Natural Science Basic research program of Shaanxi Province(2021JZ-21)+1 种基金the China Postdoctoral Science Foundation(2020M673332)Xi’an University,Xi’an Science and Technology Plan Wutongshu Technology Transfer Action Innovation Team(25WTZD07)。
文摘In this article,by employing the Hirota bilinear approach and the long wave limit method,we not only derive soliton solutions,lump solutions,and hybrid solutions for the(2+1)-dimensional Yu-Toda-Sasa-Fukuyama(YTSF)equation,but also analyze the dynamical behaviors of nonlinear local wave propagation in shallow water.Firstly,based on the Hirota bilinear approach,one to four-order soliton solutions of the YTSF equation are obtained,and the effects of different parameters on the amplitude,propagation trajectory,and displacement of solitons are investigated.Secondly,using the long wave limit approach,one to three-order lump solutions and various physical quantities of the YTSF equation are derived.It is found that the real and imaginary parts of the parameter pi dominate the propagation trajectory and the shape of lump waves,respectively.Furthermore,we construct the hybrid solution for the YTSF equation,leading to the conclusion that the interaction between lumps and solitons constitutes an elastic collision.To intuitively understand the dynamic behaviors of these solutions,we conduct numerical simulations to present vivid three-dimensional visualizations.
基金supported by the Research Fund of Guangdong University of Foreign Studies(Grant Nos.297-ZW200011 and 297-ZW230018)National Natural Science Foundation of China(Grant No.61976104).
文摘Recently,Greenfeld and Tao(2024)disproved the conjecture that translational tilings of a single tile can always be periodic.In another paper(Greenfeld and Tao(2025)),they also showed that if the dimension n is part of the input,the translational tiling for subsets of Z^(n) with one tile is undecidable.These two results are very strong pieces of evidence for the conjecture that translational tiling of Z^(n) with a monotile is undecidable for some fixed n.In this paper,we show that translational tiling of the 3-dimensional space with a set of 5 polycubes is undecidable.By introducing a technique that lifts a set of polycubes and its tiling from the 3-dimensional space to the 4-dimensional space,we manage to show that translational tiling of the 4-dimensional space with a set of 4 tiles is undecidable.This is a step towards the attempt to settle the conjecture of the undecidability of translational tiling of the n-dimensional space with a monotile for some fixed n.
基金the MR Imaging Unit at The University of Hong Kong for providing the research MRI scanning services.This work was partly supported by the General Research Fund(GRF)[grant numbers 15102118,15102219,15104323,and 15104822]the Uni-versity Grants Committee,Health and Medical Research Fund(HMRF)[grant numbers 06173276 and 10211606]+1 种基金the Health Bureau,Innova-tion and TechnologySupport Programme[grant number ITS/049/22FP]the NSFC Young Scientist Fund[grant number 82202941]from the People's Republic of China.
文摘The clinical adaptation of 4D-MRI in respiratory motion management is limited by the low image quality and motion artifacts of 4D-MRI sequences.This study aims to develop a novel artifact Map-guided Nonlocal mean(AM-NLM)technique that can be integrated into the clinical 4D-MRI workflow to suppress motion artifacts and enhance image quality.The AM-NLM technique was developed and tested on 4D-MR images of 28 liver cancer patients.A multiphase motion field was computed on the frames with the minimum average localized gradient entropy for each phase to generate a full set of improved quality 4D-MR images.Artifact maps were calculated based on the local image sharpness to guide nonlocal averaging,and a set of denoised eight-phase 4D-MR images was finally generated.The 4D-MR images were evaluated for image quality and motion accuracy.Conventional 4D-MRI approaches were also evaluated for comparison.AM-NLM 4D-MR images have significant improvements in SNR and CNR compared to the original 4D-MR images.High motion accuracy was achieved for AM-NLM 4D-MR images because the average deviation in the diaphragm position from the mean value for each phase was at the subvoxel level.Both qualitative and quantitative results suggested that the 4D-MR images generated by the AM-NLM technique had high image quality while maintaining image sharpness and motion accuracy.The AM-NLM technique has shown capability of suppressing motion artifacts and enhancing image quality of clinically acquired 4D-MR images,making it a promising technique in applications of 4D-MRI in radiotherapy.
文摘Ordered NiCo_(2)O_(4)/rGO nanowire arrays(NWAs)grown on a Ni foam substrate were synthesized using a template-free hydrothermal method and employed as an electrode with outstanding electrochemical properties for supercapacitors.After conducting a series of time-variable controlled experiments,the structure,morphology,and electrochemical properties of NiCo_(2)O_(4)/rGO NWAs were analyzed to find the most suitable growth time.Benefited from such unique array architectures,the designed NiCo_(2)O_(4)/rGO NWAs electrode demonstrates significant electrochemical properties,showing a specific capacitance of 2418 F·g^(-1)at a charge-discharge current density of 1 A·g^(-1).Moreover,it demonstrates exceptional stability,maintaining a capacity retention of 81.5%after undergoing 2,000 cycles,even when subjected to a current density of 10 A·g^(-1).The reason of high stability is that the spacing between the nanowire arrays is large and the diffusion resistance of the electrolyte is significantly reduced,which facilitates the diffusion of the electrolyte into the interior of the electrodes and establishes an effective contact with the surface of the nanowires.Furthermore,the NiCo_(2)O_(4)/rGO nanowire array grows directly on the Ni foam without binder,which establishes rapid electron transport pathways on the Ni foam substrate,resulting in excellent electrochemical properties.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.NRF-2022R1A4A1028747 and RS-2024-00344151).
文摘Recent advances in bone regeneration have introduced the concept of four-dimensional(4D)scaffolds that can undergo morphological and functional changes in response to external stimuli.While several studies have proposed patient-specific designs for defect sites,they often fail to adequately distinguish the advantages of 4D scaffolds over conventional 3D counterparts.This study aimed to investigate the potential benefits of 4D scaffolds in clinically challenging scenarios involving curved defects,where fixation is difficult.We proposed the use of Shape-Memory Polymers(SMPs)as a solution to address critical issues in personalized scaffold fabrication,including dimensional accuracy,measurement error,and manufacturing imprecision.Experimental results demonstrated that the Curved-Layer Fused Deposition Modeling(CLFDM)scaffold,which offers superior conformability to curved defects,achieved significantly higher interfacial contact with the defect area compared to traditional Fused Deposition Modeling(FDM)scaffolds.Specifically,the CLFDM scaffold facilitated bone regeneration of 25.59±4.72 mm^(3),which is more than twice the 9.37±1.36 mm^(3)observed with the 3D FDM scaffold.Furthermore,the 4D CLFDM scaffold achieved 75.38±11.65 mm^(3)of new bone formation after four weeks,approximately three times greater than that of the 3D CLFDM scaffold,regardless of surface micro-roughness.These results underscore that improved geometrical conformity between the scaffold and the defect site enhances cellular infiltration and contributes to more effective bone regeneration.The findings also highlight the promise of 4D scaffolds as a compelling strategy to overcome geometric and dimensional mismatches in the design of patient-specific scaffolds.
基金the National Natural Science Foundation of China(31972173)the Program for Science&Technology Innovation Talents of Hunan Province(2022SK2100,2021RC4032,and 2019TP1029)the Ministry of Agriculture of the People’s Republic of China(GJFP2021)。
文摘The accumulation of heavy metals in mushrooms has presented a significant risk to human health,underscoring the importance of devising a portable and cost-effective method for detecting heavy metals.Thus,we have developed an electrochemical sensor based on 3-dimensional highly reduced graphene oxide(3D-HRGO)in conjunction with Fe_(3)O_(4)nanoparticles,enabling the simultaneous quantification of Cd^(2+),Pb^(2+),Cu^(2+),and Hg^(2+).The 3D-HRGO/Fe_(3)O_(4)nano-particles material prepared in this study was characterized and confirmed by multiple techniques,then dispersed in a simple and environmental dispersant,consist of 75%ethanol and 0.1%Nafion,and coating on a glass carbon electrode(GCE)to preparing a 3D-HRGO/Fe_(3)O_(4)/GCE sensor.The limit of detection(LOD)of 3D-HRGO/Fe_(3)O_(4)/GCE sensor for Cd^(2+),Pb^(2+),Cu^(2+),and Hg^(2+)in simultaneous detection were 0.2,0.6,0.6,and 0.9μg/L,respectively.The sensor demonstrates exceptional stability,reproducibility,anti-interference,and recovery rate.Furthermore,the electrochemical sensor was employed to detect heavy metals in actual mushrooms and validated through conventional methodologies.This study represents the pioneering utilization of 3D-HRGO/Fe_(3)O_(4)as a foundational material for an electrochemical sensor capable of simultaneous detection of multiple metals,thereby advancing the progress of on-site and expeditious detection techniques.
基金supported by National Science Foundation of USA(Grant No.DMS1252992)an Alfred P.Sloan Research Fellowship
文摘We show that if the fiber of a closed 4-dimensional mapping torus X is reducible and not S2× S1 or RP3#P3, then the virtual first Betti number of X is infinite and X is not virtually symplectic. This confirms two conjectures made by Li and Ni （2014） in an earlier paper.
