Thermal diodes,based on the thermal rectification effect,have demonstrated great promise for advanced thermal management.In previous studies,almost all thermal diodes were discussed under the condition of steady state...Thermal diodes,based on the thermal rectification effect,have demonstrated great promise for advanced thermal management.In previous studies,almost all thermal diodes were discussed under the condition of steady states,while the heat source of a practical thermal system often operates under dynamically fluctuating temperatures.Therefore,in this work,we employ finite element simulation to investigate transient thermal rectification behaviors in a well-built heterojunction which exhibits intrinsic thermal rectification effect under steady state.Unidirectional energy transport in the heterojunction system,decoupled from the steady-state temperature bias,is observed under a time-dependent fluctuating heat source.This phenomenon enables straightforward realization of both giant thermal rectification and negative thermal transport.Furthermore,a series of novel thermal regulation strategies are unveiled by adjusting the average temperature,frequency,and phase of the heat source.Our work not only deepens fundamental understanding of thermal regulation in time-dependent oscillating temperature systems but also uncovers many unexplored energy-saving thermal management strategies.展开更多
Enantiomer identification is of paramount industrial value and physiological significance.Construction of sensitive chiral sensors with high enantiomeric discrimination ability is highly desirable.In this work,a chira...Enantiomer identification is of paramount industrial value and physiological significance.Construction of sensitive chiral sensors with high enantiomeric discrimination ability is highly desirable.In this work,a chiral covalent organic framework/anodic aluminum oxide(c-COF/AAO)membrane was prepared for electrochemical enantioselective recognition and sensing.Benefiting from the remarkable asymmetry,the asprepared nanofluidic c-COF/AAO presents a distinct ion current rectification(ICR)characteristic,enabling sensitive bioanalysis.In addition,owing to the large surface area,high chemical stability and perfect ion selectivity of chiral COF,the prepared c-COF/AAO membrane presents exceptionally selective mass transport and thereby enables excellent chiral discrimination for S-/R-Naproxen(S-/R-Npx)enantiomers.It is especially noteworthy that the detection limit is achieved as low as 3.88 pmol/L.These results raise the possibility for a facile,stable and low-cost method to carry out sensitive enantioselective recognition and detection.展开更多
Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectificatio...Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.展开更多
Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device...Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device level,which results in a gap to real applications.Here,we propose a controllable thermal rectification design towards building applications through the direct adhesion of composite thermal rectification material(TRM)based on PCM and reduced graphene oxide(rGO)aerogel to ordinary concrete walls(CWs).The design is evaluated in detail by combining experiments and finite element analysis.It is found that,TRM can regulate the temperature difference on both sides of the TRM/CWs system by thermal rectification.The difference in two directions reaches to 13.8 K at the heat flow of 80 W/m^(2).In addition,the larger the change of thermal conductivity before and after phase change of TRM is,the more effective it is for regulating temperature difference in two directions.The stated technology has a wide range of applications for the thermal energy control in buildings with specific temperature requirements.展开更多
Accurate segmentation of infarct tissue in ischemic stroke is essential to determine the extent of injury and assess the risk and choose optimal treatment for this life-threatening disease.With the prior knowledge tha...Accurate segmentation of infarct tissue in ischemic stroke is essential to determine the extent of injury and assess the risk and choose optimal treatment for this life-threatening disease.With the prior knowledge that asymmetric analysis of anatomical structures can provide discriminative information,plenty of symmetry-based approaches have emerged to detect abnormalities in brain images.However,the inevitable non-pathological noise has not been fully alleviated and weakened,leading to unsatisfactory results.A novel differential rectification and refinement network(DRRN)for the automatic segmentation of ischemic strokes is proposed.Specifically,a differential feature perception encoder(DFPE)is developed to fully exploit and propagate the bilateral quasi-symmetry of healthy brains.In DFPE,an erasure-rectification(ER)module is devised to rectify pseudo-lesion features caused by non-pathological noise through utilising discriminant features within the symmetric neighbourhood of the original image.And a differentialattention(DA)mechanism is also integrated to fully perceive the differences in crossaxial features and estimate the similarity of long-range spatial context information.In addition,a crisscross differential feature reinforce module embedded with multiple boundary enhancement attention modules is designed to effectively integrate multi-scale features and refine textual details and margins of the infarct area.Experimental results on the public ATLAS and Kaggle dataset demonstrate the effectiveness of DRRN over state-of-the-arts.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2023YFA1407001)Department of Science and Technology of Jiangsu Province(Grant No.BK20220032)。
文摘Thermal diodes,based on the thermal rectification effect,have demonstrated great promise for advanced thermal management.In previous studies,almost all thermal diodes were discussed under the condition of steady states,while the heat source of a practical thermal system often operates under dynamically fluctuating temperatures.Therefore,in this work,we employ finite element simulation to investigate transient thermal rectification behaviors in a well-built heterojunction which exhibits intrinsic thermal rectification effect under steady state.Unidirectional energy transport in the heterojunction system,decoupled from the steady-state temperature bias,is observed under a time-dependent fluctuating heat source.This phenomenon enables straightforward realization of both giant thermal rectification and negative thermal transport.Furthermore,a series of novel thermal regulation strategies are unveiled by adjusting the average temperature,frequency,and phase of the heat source.Our work not only deepens fundamental understanding of thermal regulation in time-dependent oscillating temperature systems but also uncovers many unexplored energy-saving thermal management strategies.
基金supported by grants from the National Natural Science Foundation of China(Nos.22274076,22304084)the Primary Research&Development Plan of Jiangsu Province(No.BE2022793)+1 种基金the Natural Science Foundation of Jiangsu Province of China(No.BK20230377)Jiangsu Provincial Department of Education(No.211090B52303)。
文摘Enantiomer identification is of paramount industrial value and physiological significance.Construction of sensitive chiral sensors with high enantiomeric discrimination ability is highly desirable.In this work,a chiral covalent organic framework/anodic aluminum oxide(c-COF/AAO)membrane was prepared for electrochemical enantioselective recognition and sensing.Benefiting from the remarkable asymmetry,the asprepared nanofluidic c-COF/AAO presents a distinct ion current rectification(ICR)characteristic,enabling sensitive bioanalysis.In addition,owing to the large surface area,high chemical stability and perfect ion selectivity of chiral COF,the prepared c-COF/AAO membrane presents exceptionally selective mass transport and thereby enables excellent chiral discrimination for S-/R-Naproxen(S-/R-Npx)enantiomers.It is especially noteworthy that the detection limit is achieved as low as 3.88 pmol/L.These results raise the possibility for a facile,stable and low-cost method to carry out sensitive enantioselective recognition and detection.
基金Project supported by the National Natural Science Foundation of China(Grant No.12364008)the Ph.D.Research Startup Foundation of Yan’an University(Grant No.YDBK2019-54)the Yan’an High-level Talent Special Project(Grant No.2019263166)。
文摘Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.
基金This work was supported in part by Tsinghua University-Zhuhai Huafa Industrial Share Company Joint Institute for Architecture Optoelectronic Technologies(JIAOT KF202204)in part by STI 2030—Major Projects under Grant 2022ZD0209200+2 种基金in part by National Natural Science Foundation of China under Grant 62374099,Grant 62022047in part by Beijing Natural Science-Xiaomi Innovation Joint Fund under Grant L233009in part by the Tsinghua-Toyota JointResearch Fund,in part by the Daikin-Tsinghua Union Program,in part sponsored by CIE-Tencent Robotics XRhino-Bird Focused Research Program.
文摘Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device level,which results in a gap to real applications.Here,we propose a controllable thermal rectification design towards building applications through the direct adhesion of composite thermal rectification material(TRM)based on PCM and reduced graphene oxide(rGO)aerogel to ordinary concrete walls(CWs).The design is evaluated in detail by combining experiments and finite element analysis.It is found that,TRM can regulate the temperature difference on both sides of the TRM/CWs system by thermal rectification.The difference in two directions reaches to 13.8 K at the heat flow of 80 W/m^(2).In addition,the larger the change of thermal conductivity before and after phase change of TRM is,the more effective it is for regulating temperature difference in two directions.The stated technology has a wide range of applications for the thermal energy control in buildings with specific temperature requirements.
基金National Natural Science Foundation of China,Grant/Award Number:No.62171251Natural Science Foundation of Guangdong Province,Grant/Award Number:No.2020A1515010711。
文摘Accurate segmentation of infarct tissue in ischemic stroke is essential to determine the extent of injury and assess the risk and choose optimal treatment for this life-threatening disease.With the prior knowledge that asymmetric analysis of anatomical structures can provide discriminative information,plenty of symmetry-based approaches have emerged to detect abnormalities in brain images.However,the inevitable non-pathological noise has not been fully alleviated and weakened,leading to unsatisfactory results.A novel differential rectification and refinement network(DRRN)for the automatic segmentation of ischemic strokes is proposed.Specifically,a differential feature perception encoder(DFPE)is developed to fully exploit and propagate the bilateral quasi-symmetry of healthy brains.In DFPE,an erasure-rectification(ER)module is devised to rectify pseudo-lesion features caused by non-pathological noise through utilising discriminant features within the symmetric neighbourhood of the original image.And a differentialattention(DA)mechanism is also integrated to fully perceive the differences in crossaxial features and estimate the similarity of long-range spatial context information.In addition,a crisscross differential feature reinforce module embedded with multiple boundary enhancement attention modules is designed to effectively integrate multi-scale features and refine textual details and margins of the infarct area.Experimental results on the public ATLAS and Kaggle dataset demonstrate the effectiveness of DRRN over state-of-the-arts.
