Handheld ultrasound devices are known for their portability and affordability,making them widely utilized in underdeveloped areas and community healthcare for rapid diagnosis and early screening.However,the image qual...Handheld ultrasound devices are known for their portability and affordability,making them widely utilized in underdeveloped areas and community healthcare for rapid diagnosis and early screening.However,the image quality of handheld ultrasound devices is not always satisfactory due to the limited equipment size,which hinders accurate diagnoses by doctors.At the same time,paired ultrasound images are difficult to obtain from the clinic because imaging process is complicated.Therefore,we propose a modified cycle generative adversarial network(cycleGAN) for ultrasound image enhancement from multiple organs via unpaired pre-training.We introduce an ultrasound image pre-training method that does not require paired images,alleviating the requirement for large-scale paired datasets.We also propose an enhanced block with different structures in the pre-training and fine-tuning phases,which can help achieve the goals of different training phases.To improve the robustness of the model,we add Gaussian noise to the training images as data augmentation.Our approach is effective in obtaining the best quantitative evaluation results using a small number of parameters and less training costs to improve the quality of handheld ultrasound devices.展开更多
Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ(HWTX-Ⅲ) and hainantoxin-VI(HNTX-VI...Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ(HWTX-Ⅲ) and hainantoxin-VI(HNTX-VI),were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography(RP-HPLC).The mechanism of action of HWTX-Ⅲ and HNTX-VI on insect neuronal voltage-gated sodium channels(VGSCs) was studied via whole-cell patch clamp techniques.In a fashion similar to δ-atracotoxins,HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na+ current in cockroach dorsal unpaired median(DUM) neurons.Meanwhile,10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel.HWTX-ⅡI inhibited VGSCs on DUM neurons(concentration of toxin at half-maximal inhibition(IC50)≈1.106 μmol/L) in a way much similar to tetrodotoxin(TTX).HWTX-Ⅲ had no effect on the kinetics of activation and inactivation.The shift in the steady-state inactivation curve was distinct from other depressant spider toxins.The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.展开更多
An EPR study of paramagnetic centers formed by irradiation of polycrystalline L-α-anhydrous asparagine (L-Asn) was performed. The EPR spectra of gamma irradiated samples at room temperature, shown the presence of thr...An EPR study of paramagnetic centers formed by irradiation of polycrystalline L-α-anhydrous asparagine (L-Asn) was performed. The EPR spectra of gamma irradiated samples at room temperature, shown the presence of three types of paramagnetic centers. A possible mechanisms of formation for the three radical species is suggested, based also on literature data. The kinetics of the disappearance of radicals during thermal annealing indicated a complex mechanism.展开更多
Organic radicals have garnered widespread attention due to their distinctive electronic,magnetic,optical,and redox properties,arising from their unpaired electrons[1].This unique characteristic profile has driven sign...Organic radicals have garnered widespread attention due to their distinctive electronic,magnetic,optical,and redox properties,arising from their unpaired electrons[1].This unique characteristic profile has driven significant advancements in radical-based materials.However,their practical application continues to encounter challenges stemming from intrinsic molecular instability.展开更多
Turbulence,a complex multi-scale phenomenon inherent in fluid flow systems,presents critical challenges and opportunities for understanding physical mechanisms across scientific and engineering domains.Although high-r...Turbulence,a complex multi-scale phenomenon inherent in fluid flow systems,presents critical challenges and opportunities for understanding physical mechanisms across scientific and engineering domains.Although high-resolution(HR)turbulence data remain indispensable for advancing both theoretical insights and engineering solutions,their acquisition is severely limited by prohibitively high computational costs.While deep learning architectures show transformative potential in reconstructing high-fidelity flow representations from sparse measurements,current methodologies suffer from two inherent constraints:strict reliance on perfectly paired training data and inability to perform multi-scale reconstruction within a unified framework.To address these challenges,we propose HADF,a hash-adaptive dynamic fusion implicit network for turbulence reconstruction.Specifically,we develop a low-resolution(LR)consistency loss that facilitates effective model training under conditions of missing paired data,eliminating the conventional requirement for fully matched LR and HR datasets.We further employ hash-adaptive spatial encoding and dynamic feature fusion to extract turbulence features,mapping them with implicit neural representations for reconstruction at arbitrary resolutions.Experimental results demonstrate that HADF achieves superior performance in global reconstruction accuracy and local physical properties compared to state-of-the-art models.It precisely recovers fine turbulence details for partially unpaired data conditions and diverse resolutions by training only once while maintaining robustness against noise.展开更多
Electron paramagnetic resonance(EPR)is a spectroscopic approach that can directly and non-destructively detect and char-acterize species with unpaired electrons,such as radicals,transi-tion metal ions,defects in mater...Electron paramagnetic resonance(EPR)is a spectroscopic approach that can directly and non-destructively detect and char-acterize species with unpaired electrons,such as radicals,transi-tion metal ions,defects in materials,and the excited triplet state of molecules[1].To date,the EPR technique has become an indis-pensable component in the toolbox of environmental studies.Using various diamagnetic probes(e.g.,5,5-dimethyl-1-pyrroline-N-oxide(DMPO))as the spin traps,transient reactive species can be transformed to EPR-detectable(meta)stable spin adducts,which enables radical identification and mechanism interpretation.Therefore,EPR constitutes a versatile platform for the mechanistic investigation of advanced oxidation processes(AOPs)in the field of water purification and contaminated groundwater remediation[2].展开更多
The discovery of efficient catalysts with suitable electronic states for CO_(2)activation is critical for advancing CO_(2)electrochemical reduction(CO_(2)ER).However,due to chemical inertness of CO_(2),seldom material...The discovery of efficient catalysts with suitable electronic states for CO_(2)activation is critical for advancing CO_(2)electrochemical reduction(CO_(2)ER).However,due to chemical inertness of CO_(2),seldom materials exhibit such characteristics without modification.Herein,we employ density functional theory(DFT)computations to demonstrate that an intrinsic antiferromagnetic Mn_(2)B_(7)monolayer characterized by alternating spin alignment prevents the complete filling of either spin-up or spin-down orbitals.This unique electronic structure provides unpaired electrons to activate CO_(2)and facilitate its conversion.As a result,Mn_(2)B_(7)monolayer exhibits superior catalytic selectivity toward CH_(4)and CH_(3)CH_(2)OH production,with low limiting potentials(-0.43 and-0.45 V)and kinetic energy barriers(<1.0 eV),significantly outperforming nonmagnetic Fe_(2)B_(7),Ru_(2)B_(7),and Os_(2)B_(7)monolayers.This study demonstrates the crucial role of adjacent antiferromagnetic unpaired electrons in CO_(2)adsorption,activation,and conversion,providing new insights into the design of highly efficient CO_(2)ER catalysts.展开更多
Spin density distributions in molecular compounds containing unpaired electrons have been studied by polarized neutron diffraction (PND). The spin density distributions provide a unique perspective of the magnetic pro...Spin density distributions in molecular compounds containing unpaired electrons have been studied by polarized neutron diffraction (PND). The spin density distributions provide a unique perspective of the magnetic properties of the compounds. The background and fundamentals of polarized neutron diffraction are summarized in this review,followed by examples of applications in inorganic and organic chemistry. Spin densities in several compounds that are obtained by polarized neutron diffraction are highlighted. Spin densities in single molecular magnet [Fe8O2(OH)12(tacn)6]8+ and cyano-bridged K2[Mn(H2O)2]3[Mo(CN)7]2·6H2O demonstrate how to obtain magnetic interaction in the complexes by PND. PND studies of Ru(acac)3,containing one single unpaired electron,show small spin densities in this complex. Finally the use of PND in studying nitronyl nitroxide radicals is given. Our goal in this review is to illustrate how PND functions and how it serves as a sensitive tool in directly probing spin density in molecules.展开更多
文摘Handheld ultrasound devices are known for their portability and affordability,making them widely utilized in underdeveloped areas and community healthcare for rapid diagnosis and early screening.However,the image quality of handheld ultrasound devices is not always satisfactory due to the limited equipment size,which hinders accurate diagnoses by doctors.At the same time,paired ultrasound images are difficult to obtain from the clinic because imaging process is complicated.Therefore,we propose a modified cycle generative adversarial network(cycleGAN) for ultrasound image enhancement from multiple organs via unpaired pre-training.We introduce an ultrasound image pre-training method that does not require paired images,alleviating the requirement for large-scale paired datasets.We also propose an enhanced block with different structures in the pre-training and fine-tuning phases,which can help achieve the goals of different training phases.To improve the robustness of the model,we add Gaussian noise to the training images as data augmentation.Our approach is effective in obtaining the best quantitative evaluation results using a small number of parameters and less training costs to improve the quality of handheld ultrasound devices.
基金supported by the National Natural Science Foundation of China (No.30500146)the National Basic Research Program (973) of China (No.2006CB708508)
文摘Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ(HWTX-Ⅲ) and hainantoxin-VI(HNTX-VI),were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography(RP-HPLC).The mechanism of action of HWTX-Ⅲ and HNTX-VI on insect neuronal voltage-gated sodium channels(VGSCs) was studied via whole-cell patch clamp techniques.In a fashion similar to δ-atracotoxins,HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na+ current in cockroach dorsal unpaired median(DUM) neurons.Meanwhile,10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel.HWTX-ⅡI inhibited VGSCs on DUM neurons(concentration of toxin at half-maximal inhibition(IC50)≈1.106 μmol/L) in a way much similar to tetrodotoxin(TTX).HWTX-Ⅲ had no effect on the kinetics of activation and inactivation.The shift in the steady-state inactivation curve was distinct from other depressant spider toxins.The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.
文摘An EPR study of paramagnetic centers formed by irradiation of polycrystalline L-α-anhydrous asparagine (L-Asn) was performed. The EPR spectra of gamma irradiated samples at room temperature, shown the presence of three types of paramagnetic centers. A possible mechanisms of formation for the three radical species is suggested, based also on literature data. The kinetics of the disappearance of radicals during thermal annealing indicated a complex mechanism.
文摘Organic radicals have garnered widespread attention due to their distinctive electronic,magnetic,optical,and redox properties,arising from their unpaired electrons[1].This unique characteristic profile has driven significant advancements in radical-based materials.However,their practical application continues to encounter challenges stemming from intrinsic molecular instability.
基金Project supported by the National Natural Science Foundation of China(No.12402349)the Natural Science Foundation of Hunan Province(No.2024JJ6468)+1 种基金the Youth Foundation of the National University of Defense Technology(No.ZK2023-11)the National Key Research and Development Program of China(No.2021YFB0300101)。
文摘Turbulence,a complex multi-scale phenomenon inherent in fluid flow systems,presents critical challenges and opportunities for understanding physical mechanisms across scientific and engineering domains.Although high-resolution(HR)turbulence data remain indispensable for advancing both theoretical insights and engineering solutions,their acquisition is severely limited by prohibitively high computational costs.While deep learning architectures show transformative potential in reconstructing high-fidelity flow representations from sparse measurements,current methodologies suffer from two inherent constraints:strict reliance on perfectly paired training data and inability to perform multi-scale reconstruction within a unified framework.To address these challenges,we propose HADF,a hash-adaptive dynamic fusion implicit network for turbulence reconstruction.Specifically,we develop a low-resolution(LR)consistency loss that facilitates effective model training under conditions of missing paired data,eliminating the conventional requirement for fully matched LR and HR datasets.We further employ hash-adaptive spatial encoding and dynamic feature fusion to extract turbulence features,mapping them with implicit neural representations for reconstruction at arbitrary resolutions.Experimental results demonstrate that HADF achieves superior performance in global reconstruction accuracy and local physical properties compared to state-of-the-art models.It precisely recovers fine turbulence details for partially unpaired data conditions and diverse resolutions by training only once while maintaining robustness against noise.
文摘Electron paramagnetic resonance(EPR)is a spectroscopic approach that can directly and non-destructively detect and char-acterize species with unpaired electrons,such as radicals,transi-tion metal ions,defects in materials,and the excited triplet state of molecules[1].To date,the EPR technique has become an indis-pensable component in the toolbox of environmental studies.Using various diamagnetic probes(e.g.,5,5-dimethyl-1-pyrroline-N-oxide(DMPO))as the spin traps,transient reactive species can be transformed to EPR-detectable(meta)stable spin adducts,which enables radical identification and mechanism interpretation.Therefore,EPR constitutes a versatile platform for the mechanistic investigation of advanced oxidation processes(AOPs)in the field of water purification and contaminated groundwater remediation[2].
基金support from the Youth Development Foundation of Jilin Province(No.20230508183RC)the National Natural Science Foundation of China(Nos.22403014 and 21673036)+1 种基金the China Postdoctoral Science Foundation(Nos.2023M730539 and 2024T170121)the Fundamental Research Funds for the Central Universities(Nos.2412022ZD050 and 2412023QD012).
文摘The discovery of efficient catalysts with suitable electronic states for CO_(2)activation is critical for advancing CO_(2)electrochemical reduction(CO_(2)ER).However,due to chemical inertness of CO_(2),seldom materials exhibit such characteristics without modification.Herein,we employ density functional theory(DFT)computations to demonstrate that an intrinsic antiferromagnetic Mn_(2)B_(7)monolayer characterized by alternating spin alignment prevents the complete filling of either spin-up or spin-down orbitals.This unique electronic structure provides unpaired electrons to activate CO_(2)and facilitate its conversion.As a result,Mn_(2)B_(7)monolayer exhibits superior catalytic selectivity toward CH_(4)and CH_(3)CH_(2)OH production,with low limiting potentials(-0.43 and-0.45 V)and kinetic energy barriers(<1.0 eV),significantly outperforming nonmagnetic Fe_(2)B_(7),Ru_(2)B_(7),and Os_(2)B_(7)monolayers.This study demonstrates the crucial role of adjacent antiferromagnetic unpaired electrons in CO_(2)adsorption,activation,and conversion,providing new insights into the design of highly efficient CO_(2)ER catalysts.
基金Supported by a JINS (Joint Institute for Neutron Sciences) fellowshipthe US National Science Foundation (CHE-0516928)
文摘Spin density distributions in molecular compounds containing unpaired electrons have been studied by polarized neutron diffraction (PND). The spin density distributions provide a unique perspective of the magnetic properties of the compounds. The background and fundamentals of polarized neutron diffraction are summarized in this review,followed by examples of applications in inorganic and organic chemistry. Spin densities in several compounds that are obtained by polarized neutron diffraction are highlighted. Spin densities in single molecular magnet [Fe8O2(OH)12(tacn)6]8+ and cyano-bridged K2[Mn(H2O)2]3[Mo(CN)7]2·6H2O demonstrate how to obtain magnetic interaction in the complexes by PND. PND studies of Ru(acac)3,containing one single unpaired electron,show small spin densities in this complex. Finally the use of PND in studying nitronyl nitroxide radicals is given. Our goal in this review is to illustrate how PND functions and how it serves as a sensitive tool in directly probing spin density in molecules.
