The traditional small target detection algorithm often results in a high false alarm rate on the sea surface background. To address this issue, a small target detection method based on guided filtering and local avera...The traditional small target detection algorithm often results in a high false alarm rate on the sea surface background. To address this issue, a small target detection method based on guided filtering and local average gray level difference was proposed in this paper for the sea surface. Firstly, the method enhanced the details of the small targets by employing guided filtering to suppress the background clutter and noise in the sea surface image. Subsequently, the local average gray level difference of each point in the image was calculated to further distinguish the targets from other interference points. Finally, the threshold segmentation method was utilized to obtain the actual small targets on the sea surface. After conducting experiments on various sea surface scenes, the LSCRG, BSF, and ROC curve were computed for the proposed method and five other algorithms. Comparative analysis with BS, Top-hat, TDLMS, Max-median, and LCM demonstrates the superiority of the proposed method for infrared small target detection on the sea surface.展开更多
BACKGROUND: Human amniotic epithelial cells (HAECs) can differentiate into neurons, astrocytes,and oligodendrocytes. They biologically secrete many active neurotrophins and have the capacity tometabolize dopamine enzy...BACKGROUND: Human amniotic epithelial cells (HAECs) can differentiate into neurons, astrocytes,and oligodendrocytes. They biologically secrete many active neurotrophins and have the capacity tometabolize dopamine enzymes. These features underlie a theoretical basis for the treatment ofParkinson's disease (PD).OBJECTIVE: To investigate the survival and differentiation of transplanted HAECs in the lateralventricle of PD model rats, and to explore its effect on circling behavior, as well as levels ofdopamine (DA), the metabolite homovanillic acid, dihydroxyphenyl acetic acid,5-hydroxyindoleacetic acid, and 5-hydroxytryptamine in the striatum.DESIGN, TIME AND SETTING: A randomized, controlled, animal study was performed at theInstitute of Biochemistry and Cell Biology, Shanghai Institute for Biological Sciences, ChineseAcademy of Sciences, and Shanghai Celstar Institute of Biotechnology from May 2007 to December2008.MATERIALS: HAECs were derived from the placental chorion following caesarean delivery at theShanghai International Maternal and Child Health Hospital. 6-hydroxydopamine (6-OHDA), andmouse anti-human Vimentin monoclonal antibody were purchased from Sigma, USA; mouseanti-human nestin and tyrosine hydroxylase (TH) monoclonal antibodies were purchased fromChemicon, USA.METHODS: A total of 114 healthy, adult, Sprague Dawley rats were randomly assigned to twogroups: PD model [n = 90, stereotactic microinjection of 2 μL 6-OHDA (3.5 μg/μL) into the striatum]and control (n = 24, no treatment). The 51 successful PD model rats were randomly divided into 3subgroups (n = 17): HAEC, PBS, and model. The HAEC and PBS groups were respectively injectedwith 10 μL PBS solution containing 1 x 105/mL HAECs or 10 μL PBS into the lateral ventricle. Themodel group was not treated.MAIN OUTCOME MEASURES: TH protein expression in the striatum was evaluated byimmunohistochemistry 5 weeks after HAEC transplantation. At 10 weeks, HAEC survival in thelateral ventricle was investigated by immunofluorescent staining; differentiation of HAECs in thelateral and third ventricles was examined by TH immunohistochemistry; concentrations of DA,homovanillic acid, dihydroxyphenyl acetic acid, 5-hydroxyindoleacetic acid, and 5-hydroxytryptaminein the striatum, as well as DA concentration in the cerebrospinal fluid, were measured withhigh-performance liquid chromatography-electrochemical detection. Circling behavior of PD modelrats was consecutively observed for 10 weeks following intraperitoneal injection of amphetamine 1week after successful model establishment.RESULTS: In the HAEC group, the number of TH-positive cells significantly increased in thestriatum, and circling behavior significantly decreased, compared with the PBS and model groups(P < 0.01). In addition, monoamine concentrations in the striatum, as well as DA concentrations inthe cerebrospinal fluid, significantly increased, compared with the PBS group (P < 0.05-0.01 ).Moreover, a large number of nestin-, vimentin-, and TH-positive cells were observed in the lateraland third ventricles following HAEC injection. CONCLUSION: HAECs survived for 10 weeks with no overgrowth following transplantation into thelateral ventricle of PD model rats. Moreover, the cells differentiated into dopaminergic neurons,which increased DA secretion. HAEC transplantation improved cycling behavior in PD model rats.展开更多
Molybdenum phosphide(MoP),owing to its abundant reserve and high theoretical capacity,is regarded as a promising anode material for potassium-ion batteries.However,it still suffers from the problems of acute volume ex...Molybdenum phosphide(MoP),owing to its abundant reserve and high theoretical capacity,is regarded as a promising anode material for potassium-ion batteries.However,it still suffers from the problems of acute volume expansion and weak diffusion kinetics.This study reports a simple method to synthesize a composite of molybdenum phosphide and porous carbon(MoP@PC)through simple mixing and annealing treatment.In the MoP@PC,lots of MoP nanodots with an average diameter of about 4 nm uniformly embedded in the petal-like porous carbon.The MoP@PC shows reversible capacities of 330 mAh g^(-1) at100 mA g^(-1) after 100 cycles,and ultra-long cycling stability with a capacity of 240 mAh g^(-1) after 1000 cycles at 1 A g^(-1) and 161 mAh g^(-1) after 1000 cycles at 5 A g^(-1).The structure of MoP@PC after charging-discharging cycles is also investigated by high resolution transmission electron microscope(HRTEM)and the result shows that MoP can still maintain the nanodot morphology without any agglomeration after 1000 cycles at 5 A g^(-1).The storage mechanism of potassium ions was studied as well,which reveals that MoP and potassium ion have a conversion reaction.展开更多
The Na^(+)/vacancy ordering can effectively affect the electrochemical behavior of P2-type cathode material.In this work we proposed an integrated strategy by attaining a high Na content,In^(3+) doping in conjunction ...The Na^(+)/vacancy ordering can effectively affect the electrochemical behavior of P2-type cathode material.In this work we proposed an integrated strategy by attaining a high Na content,In^(3+) doping in conjunction with NaInO_(2) coating in the P2-Na_(0.75)Mn_(0.67)Ni_(0.33)O_(2) which can inhibit the sodium vacancy order,smooth the electrochemical curve,and enhance the structural stability and rate capability.A combination of X-ray diffraction analysis and DFT calculation indicate that the In(3+) ions in the Na layer serve as"pillars”to stabilize the layered structure,especially for high current density charging.The P2-Na_(0.75)Mn_(0.67)Ni_(0.33)In_(0.02)O_(2) with an impressive sodium content exhibits a remarkable reversible capacity of 109.6 mAh g^(-1),superior rate capability capacity of 79.8 mAh g^(-1)at 20 C,and 85%capacity retention after 100 cycles at 5 C.This work demonstrates an efficient approach for the comprehensive optimization of sodium ion cathode materials.展开更多
Zinc-based degradable metals are considered one of the most promising biodegradable materials due to their moderate corrosion rate,excellent mechanical properties,and good biocompatibility.In this work,biodegradable Z...Zinc-based degradable metals are considered one of the most promising biodegradable materials due to their moderate corrosion rate,excellent mechanical properties,and good biocompatibility.In this work,biodegradable Zn-0.4Mn-0.8Li alloy was fabricated and rolled in multiple passes at different tem peratures.As the hot rolling temperature increases,the grain size of Zn-0.4Mn-0.8Li alloy was found to increase cor-respondingly.Further,a multi-scale structure with the coexistence of coarse grains and fine grains was obtained.The results demonstrated that the mechanical strength and corrosion resistance were improved by increasing the rolled temperature.It was observed that Zn-0.4Mn-0.8Li alloy with a total reduction of 90%after hot rolling at 325℃ exhibited excellent mechanical and corrosion properties.The cooperation of multi-scale microstructure and twinning was found to improve the strength and guarantee the duc-tility of Zn-0.4Mn-0.8Li alloy significantly so that the 325℃ hot-rolled Zn-0.4Mn-0.8Li alloy has optimal comprehensive properties.Further,yield strength,ultimate tensile strength,and elongation were found to be 449.7±5.3 MPa,505.1±6.5 MPa,and 40.5%±7.5%,respectively.Meanwhile,Zn-0.4Mn-0.8Li al-loy via 325℃ hot-rolled processes also exhibited excellent corrosion resistance.The corrosion current density and corrosion potential were found to be 8.8×10-5 mA cm^(-2)and−0.929 V,respectively.The preliminary study indicates that Zn-0.4Mn-0.8Li alloy is a promising candidate material for medical de-vice applications.展开更多
由于其电热输运性能便于调控,锑基Zintl相化合物AM2Sb2(A=Ca,Sr,Ba,Yb,Eu;M=Mg,Zn,Cd,Mn)被认为是一类重要的热电材料.本文通过在YbMg2Sb2中掺入等价的元素Zn和异价元素Ag,实现了声子和载流子的输运性能优化.首先,体系YbMg2-xZnxSb2室...由于其电热输运性能便于调控,锑基Zintl相化合物AM2Sb2(A=Ca,Sr,Ba,Yb,Eu;M=Mg,Zn,Cd,Mn)被认为是一类重要的热电材料.本文通过在YbMg2Sb2中掺入等价的元素Zn和异价元素Ag,实现了声子和载流子的输运性能优化.首先,体系YbMg2-xZnxSb2室温热导率从1.96 W m^-1K^-1降低至1.15 W m^-1K^-1,这是由于形成YbMg2Sb2-YbZn2Sb2的固溶体带来的合金化散射效应.其次,掺杂Ag可以增加载流子浓度,其数值在室温下从0.42×10^19cm^-3提升至7.72×10^19cm^-3,从而有效地提高了电导率和功率因子.通过综合两方面的协同效应使得体系zT在703 K时达到0.48,比纯样品YbMgZnSb2高60%.展开更多
Radio Frequency(RF) technology represents a high-precision relative navigation solution that has significant potential for application to earth-orbiting satellites. In precision applications, multipath errors dominate...Radio Frequency(RF) technology represents a high-precision relative navigation solution that has significant potential for application to earth-orbiting satellites. In precision applications, multipath errors dominate the total error because observables, which are used to estimate carrier-phase integer ambiguity, are not always subject to a Gaussian distribution when dualfrequency ambiguity estimation methods are used in the presence of multipath. As it has been shown that ranging observables obey a Gaussian mixture distribution, this study proposes improvements to the accuracy of estimation based on multipath mitigation founded on the Gaussian mixture model. To this end, such a model is created for integer ambiguity resolution in the presence of multipath, using which the theoretical error in dual-frequency ambiguity estimation is derived.Expectation Maximization(EM), which aids dual-frequency ambiguity estimation, is subsequently proposed to reduce the effect of multipath errors. Finally, two experimental scenarios are implemented to test the performance of the proposed method. The results show that EM-aided dualfrequency ambiguity estimation reduces the range error to approximately 20% in comparison with simple dual-frequency ambiguity estimation. Therefore the proposed technique is effective for multipath mitigation in RF relative measurement.展开更多
CD4^(+)T cells are essential for sustaining CD8^(+)T cell responses during a chronic infection.The adoptive transfer of virus-specific CD4^(+)T cells has been shown to efficiently rescue exhausted CD8^(+)T cells.Howev...CD4^(+)T cells are essential for sustaining CD8^(+)T cell responses during a chronic infection.The adoptive transfer of virus-specific CD4^(+)T cells has been shown to efficiently rescue exhausted CD8^(+)T cells.However,the question of whether endogenous virus-specific CD4^(+)T cell responses can be enhanced by certain vaccination strategies and subsequently reinvigorate exhausted CD8^(+)T cells remains unexplored.In this study,we developed a CD4^(+)T cell epitope-based heterologous prime-boost immunization strategy and examined the efficacy of this strategy using a mouse model of chronic lymphocytic choriomeningitis virus(LCMV)infection.We primed chronically LCMV-infected mice with a Listeria monocytogenes vector that expressed the LCMV glycoprotein-specific I-Ab-restricted CD4^(+)T cell epitope GP61–80(LM-GP61)and subsequently boosted the primed mice with an influenza virus A(PR8 strain)vector that expressed the same CD4^(+)T cell epitope(IAV-GP61).This heterologous prime-boost vaccination strategy elicited strong anti-viral CD4^(+)T cell responses,which further improved both the quantity and quality of the virusspecific CD8^(+)T cells and led to better control of the viral loads.The combination of this strategy and the blockade of the programmed cell death-1(PD-1)inhibitory pathway further enhanced the anti-viral CD8^(+)T cell responses and viral clearance.Thus,a heterologous prime-boost immunization that selectively induces virus-specific CD4^(+)T cell responses in conjunction with blockade of the inhibitory pathway may represent a promising therapeutic approach to treating patients with chronic viral infections.展开更多
Nuclear power development is a complex issue spanning cyber,physical,and social systems that is essential to achieving energy security and climate goals.With the ongoing worldwide trend towards carbon neutrality,the p...Nuclear power development is a complex issue spanning cyber,physical,and social systems that is essential to achieving energy security and climate goals.With the ongoing worldwide trend towards carbon neutrality,the positioning of nuclear power in energy mix should be reconsidered.This paper aims to present a systematic review of current research on optimization of nuclear power development.The concept of cyber-physical-social system in energy(CPSSE)is adopted,which provides a suitable perspective and enables the review of relevant studies to achieve some novel insights.Based on the CPSSE,firstly,a research framework is established and the main research elements in optimization are identified,followed by a proposed conceptual risk-based optimization model.Secondly,current studies are analyzed and classified into four categories according to the research boundary.The status quo and limitations are discussed.It is found that the research results of nuclear-specific issues have not been well integrated into the optimization of nuclear power.As a relatively reliable power supply,nuclear power is capable of maintaining power and electricity adequacy of the whole system,especially in the case of power shortage caused by long-period low output of renewable energy or extreme external disasters.This superiority should not be ignored in the optimization.Other critical factors that should be further considered include disruptive technologies,nuclear safety,energy policies,and stakeholder behaviors.Finally,suggestions are given for future research.展开更多
The contradiction between the strength and ductility of metallic materials is a major scientific problemthat has been researched for a long time. Dual-phase equiatomic and non-equiatomic Ti-Zr-Nb-Ta highentropy alloys...The contradiction between the strength and ductility of metallic materials is a major scientific problemthat has been researched for a long time. Dual-phase equiatomic and non-equiatomic Ti-Zr-Nb-Ta highentropy alloys (HEAs) with super-high strength and excellent ductility have been successfully developedvia mechanical alloying (MA) combined with spark plasma sintering (SPS) technology. This is adjustedby altering the atomic ratios of the different phases. X-ray diffraction (XRD) and transmission electronmicroscopy (TEM) were performed to confirm the dual-phase microstructure. After the SPS process, theaverage grain size of the aforementioned equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAs (134 ± 50 nm) evaluated byelectron back-scattering diffraction (EBSD) is smaller than that of the Ti-Zr-Nb-Ta HEAs (150 μm), whichwere fabricated using arc melting. According to the Hall-Petch formula, the grain boundary strengthening contribution in the Ti-Zr-Nb-Ta system is 33-fold higher than those fabricated using the arc-meltingprocess. When the alloy phase comprises the equivalent dual-phase, equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAshave good comprehensive performance compared to non-equiatomic Ti-Zr-Nb-Ta HEAs prepared usingthe same process. The yield strength of equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAs (2212 ± 38 MPa) is two-foldhigher than that of Ti-Zr-Nb-Ta HEAs (1100 ± 90 MPa) fabricated via arc melting. This can be attributed tothe ultra-fine grain size. Notably, the equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAs possess approximately the samebiocompatibility as commercial pure Ti (CP-Ti), indicating that the equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAs areprovided with a possibility as an advanced biomaterial for the applications of the medical field.展开更多
NaxCoO_(2)was known 20 years ago as a unique example in which spin entropy dominates the thermoelectric behavior.Hitherto,however,little has been learned about how to manipulate the spin degree of freedom in thermoele...NaxCoO_(2)was known 20 years ago as a unique example in which spin entropy dominates the thermoelectric behavior.Hitherto,however,little has been learned about how to manipulate the spin degree of freedom in thermoelectrics.Here,we report the enhanced thermoelectric performance of GeMnTe_(2)by controlling the spin’s thermodynamic entropy.The anomalously large thermopower of GeMnTe_(2)is demonstrated to originate from the disordering of spin orientation under finite temperature.Based on the careful analysis of Heisenberg model,it is indicated that the spin-system entropy can be tuned by modifying the hybridization between Te-p and Mn-d orbitals.As a consequent strategy,Se doping enlarges the thermopower effectively,while neither carrier concentration nor band gap is affected.The measurement of magnetic susceptibility provides a solid evidence for the inherent relationship between the spin’s thermodynamic entropy and thermopower.By further introducing Bi doing,the maximum ZT in Ge_(0.94)Bi_(0.06)MnTe_(1.94)Se_(0.06)reaches 1.4 at 840 K,which is 45%higher than the previous report of Bi-doped GeMnTe_(2).This work reveals the high thermoelectric performance of GeMnTe_(2)and also provides an insightful understanding of the spin degree of freedom in thermoelectrics.展开更多
Protein–protein interaction(PPI)networks are key to nearly all aspects of cellular activity.Therefore,the identification of PPIs is important for understanding a specific biological process in an organism.Compared wi...Protein–protein interaction(PPI)networks are key to nearly all aspects of cellular activity.Therefore,the identification of PPIs is important for understanding a specific biological process in an organism.Compared with conventional methods for probing PPIs,the recently described proximity labeling(PL)approach combined with mass spectrometry(MS)-based quantitative proteomics hasemerged as apowerful approach for characterizing PPIs.However,the application of PL in planta remains in its infancy.Here,we summarize recent progress in PL and its potential utilization in plant biology.We specifically summarize advances in PL,including the development and comparison of different PL enzymes and the application of PL for deciphering various molecular interactions in different organisms with an emphasis on plant systems.展开更多
O3-type layered oxide cathodes have been widely investigated due to their high reversible capacities and sufficient Na+reservoirs.However,such materials usually suffer from complex multistep phase transitions along wi...O3-type layered oxide cathodes have been widely investigated due to their high reversible capacities and sufficient Na+reservoirs.However,such materials usually suffer from complex multistep phase transitions along with drastic volume changes,leading to the unsatisfied cycle performance.Herein,we report a Mg/Ti co-doped O3-type NaNi_(0.5)Mn_(0.5)O_(2),which can effectively suppress the complex multistep phase transition and realize a solid-solution reaction within a wide voltage range.It is confirmed that,the Mg/Ti co-doping is beneficial to enhance the structural stability and integrity by absorbing micro-strain and distortions.Thus,the as obtained sample delivers an outstanding cyclic performance(82.3%after 200 cycles at 1 C)in the voltage range of 2.0-4.0 V,and a high discharge capacity of 86.6 mAh/g after 100 cycles within the wide voltage range(2.0-4.5 V),which outperform the existing literatures.This co-doping strategy offers new insights into high performance O3-type cathode for sodium ion batteries.展开更多
文摘The traditional small target detection algorithm often results in a high false alarm rate on the sea surface background. To address this issue, a small target detection method based on guided filtering and local average gray level difference was proposed in this paper for the sea surface. Firstly, the method enhanced the details of the small targets by employing guided filtering to suppress the background clutter and noise in the sea surface image. Subsequently, the local average gray level difference of each point in the image was calculated to further distinguish the targets from other interference points. Finally, the threshold segmentation method was utilized to obtain the actual small targets on the sea surface. After conducting experiments on various sea surface scenes, the LSCRG, BSF, and ROC curve were computed for the proposed method and five other algorithms. Comparative analysis with BS, Top-hat, TDLMS, Max-median, and LCM demonstrates the superiority of the proposed method for infrared small target detection on the sea surface.
基金Supported by: the Major State Basic Research Development Program of China (973 Program), No.2005CB522604the National Natural Science Foundation of China, No. 30271325
文摘BACKGROUND: Human amniotic epithelial cells (HAECs) can differentiate into neurons, astrocytes,and oligodendrocytes. They biologically secrete many active neurotrophins and have the capacity tometabolize dopamine enzymes. These features underlie a theoretical basis for the treatment ofParkinson's disease (PD).OBJECTIVE: To investigate the survival and differentiation of transplanted HAECs in the lateralventricle of PD model rats, and to explore its effect on circling behavior, as well as levels ofdopamine (DA), the metabolite homovanillic acid, dihydroxyphenyl acetic acid,5-hydroxyindoleacetic acid, and 5-hydroxytryptamine in the striatum.DESIGN, TIME AND SETTING: A randomized, controlled, animal study was performed at theInstitute of Biochemistry and Cell Biology, Shanghai Institute for Biological Sciences, ChineseAcademy of Sciences, and Shanghai Celstar Institute of Biotechnology from May 2007 to December2008.MATERIALS: HAECs were derived from the placental chorion following caesarean delivery at theShanghai International Maternal and Child Health Hospital. 6-hydroxydopamine (6-OHDA), andmouse anti-human Vimentin monoclonal antibody were purchased from Sigma, USA; mouseanti-human nestin and tyrosine hydroxylase (TH) monoclonal antibodies were purchased fromChemicon, USA.METHODS: A total of 114 healthy, adult, Sprague Dawley rats were randomly assigned to twogroups: PD model [n = 90, stereotactic microinjection of 2 μL 6-OHDA (3.5 μg/μL) into the striatum]and control (n = 24, no treatment). The 51 successful PD model rats were randomly divided into 3subgroups (n = 17): HAEC, PBS, and model. The HAEC and PBS groups were respectively injectedwith 10 μL PBS solution containing 1 x 105/mL HAECs or 10 μL PBS into the lateral ventricle. Themodel group was not treated.MAIN OUTCOME MEASURES: TH protein expression in the striatum was evaluated byimmunohistochemistry 5 weeks after HAEC transplantation. At 10 weeks, HAEC survival in thelateral ventricle was investigated by immunofluorescent staining; differentiation of HAECs in thelateral and third ventricles was examined by TH immunohistochemistry; concentrations of DA,homovanillic acid, dihydroxyphenyl acetic acid, 5-hydroxyindoleacetic acid, and 5-hydroxytryptaminein the striatum, as well as DA concentration in the cerebrospinal fluid, were measured withhigh-performance liquid chromatography-electrochemical detection. Circling behavior of PD modelrats was consecutively observed for 10 weeks following intraperitoneal injection of amphetamine 1week after successful model establishment.RESULTS: In the HAEC group, the number of TH-positive cells significantly increased in thestriatum, and circling behavior significantly decreased, compared with the PBS and model groups(P < 0.01). In addition, monoamine concentrations in the striatum, as well as DA concentrations inthe cerebrospinal fluid, significantly increased, compared with the PBS group (P < 0.05-0.01 ).Moreover, a large number of nestin-, vimentin-, and TH-positive cells were observed in the lateraland third ventricles following HAEC injection. CONCLUSION: HAECs survived for 10 weeks with no overgrowth following transplantation into thelateral ventricle of PD model rats. Moreover, the cells differentiated into dopaminergic neurons,which increased DA secretion. HAEC transplantation improved cycling behavior in PD model rats.
基金supported by the National Natural Science Foundation of China(Grant Nos.51974114,51672075 and 21908049)Natural Science Foundation of Hunan Province(Grant No.2020JJ4175)the Fundamental Research Funds for the Central Universities。
文摘Molybdenum phosphide(MoP),owing to its abundant reserve and high theoretical capacity,is regarded as a promising anode material for potassium-ion batteries.However,it still suffers from the problems of acute volume expansion and weak diffusion kinetics.This study reports a simple method to synthesize a composite of molybdenum phosphide and porous carbon(MoP@PC)through simple mixing and annealing treatment.In the MoP@PC,lots of MoP nanodots with an average diameter of about 4 nm uniformly embedded in the petal-like porous carbon.The MoP@PC shows reversible capacities of 330 mAh g^(-1) at100 mA g^(-1) after 100 cycles,and ultra-long cycling stability with a capacity of 240 mAh g^(-1) after 1000 cycles at 1 A g^(-1) and 161 mAh g^(-1) after 1000 cycles at 5 A g^(-1).The structure of MoP@PC after charging-discharging cycles is also investigated by high resolution transmission electron microscope(HRTEM)and the result shows that MoP can still maintain the nanodot morphology without any agglomeration after 1000 cycles at 5 A g^(-1).The storage mechanism of potassium ions was studied as well,which reveals that MoP and potassium ion have a conversion reaction.
基金supported by the National Natural Science Foundation of China (22179077, 51774251)the Shanghai Science and Technology Commission’s “2020 Science and Technology Innovation Action Plan” (20511104003)+2 种基金the Natural Science Foundation in Shanghai (21ZR1424200)the Hebei Natural Science Foundation for Distinguished Young Scholars (B2017203313)the Scientific Research Foundation for the Returned Overseas Chinese Scholars (CG2014003002)。
文摘The Na^(+)/vacancy ordering can effectively affect the electrochemical behavior of P2-type cathode material.In this work we proposed an integrated strategy by attaining a high Na content,In^(3+) doping in conjunction with NaInO_(2) coating in the P2-Na_(0.75)Mn_(0.67)Ni_(0.33)O_(2) which can inhibit the sodium vacancy order,smooth the electrochemical curve,and enhance the structural stability and rate capability.A combination of X-ray diffraction analysis and DFT calculation indicate that the In(3+) ions in the Na layer serve as"pillars”to stabilize the layered structure,especially for high current density charging.The P2-Na_(0.75)Mn_(0.67)Ni_(0.33)In_(0.02)O_(2) with an impressive sodium content exhibits a remarkable reversible capacity of 109.6 mAh g^(-1),superior rate capability capacity of 79.8 mAh g^(-1)at 20 C,and 85%capacity retention after 100 cycles at 5 C.This work demonstrates an efficient approach for the comprehensive optimization of sodium ion cathode materials.
基金The work was financially supported by the National Natural Science Foundation of China(No.51871077)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515012626)+1 种基金the Shenzhen Knowledge Innovation Plan-Fundamental Research(Discipline Distribution)(No.JCYJ20180507184623297)the Startup Foundation from Shenzhen and Startup Foundation from Harbin Institute of Technology(Shenzhen),and the Development and Reform Commission of Shenzhen Municipality Shenzhen R&D Center for Al-based Hydrogen Hydrolysis Materials(No.ZX20190229).
文摘Zinc-based degradable metals are considered one of the most promising biodegradable materials due to their moderate corrosion rate,excellent mechanical properties,and good biocompatibility.In this work,biodegradable Zn-0.4Mn-0.8Li alloy was fabricated and rolled in multiple passes at different tem peratures.As the hot rolling temperature increases,the grain size of Zn-0.4Mn-0.8Li alloy was found to increase cor-respondingly.Further,a multi-scale structure with the coexistence of coarse grains and fine grains was obtained.The results demonstrated that the mechanical strength and corrosion resistance were improved by increasing the rolled temperature.It was observed that Zn-0.4Mn-0.8Li alloy with a total reduction of 90%after hot rolling at 325℃ exhibited excellent mechanical and corrosion properties.The cooperation of multi-scale microstructure and twinning was found to improve the strength and guarantee the duc-tility of Zn-0.4Mn-0.8Li alloy significantly so that the 325℃ hot-rolled Zn-0.4Mn-0.8Li alloy has optimal comprehensive properties.Further,yield strength,ultimate tensile strength,and elongation were found to be 449.7±5.3 MPa,505.1±6.5 MPa,and 40.5%±7.5%,respectively.Meanwhile,Zn-0.4Mn-0.8Li al-loy via 325℃ hot-rolled processes also exhibited excellent corrosion resistance.The corrosion current density and corrosion potential were found to be 8.8×10-5 mA cm^(-2)and−0.929 V,respectively.The preliminary study indicates that Zn-0.4Mn-0.8Li alloy is a promising candidate material for medical de-vice applications.
基金supported by the National Key Research and Development Program of China (2018YFA0702100)the National Natural Science Foundation of China (21771123)+2 种基金the Programme of Introducing Talents of Discipline to Universities (D16002)the Science and Technology Commission of Shanghai Municipality (15DZ2260300)Key Laboratory of Optoelectronic Materials Chemistry and Physics, Chinese Academy of Sciences (2008DP173016)
文摘由于其电热输运性能便于调控,锑基Zintl相化合物AM2Sb2(A=Ca,Sr,Ba,Yb,Eu;M=Mg,Zn,Cd,Mn)被认为是一类重要的热电材料.本文通过在YbMg2Sb2中掺入等价的元素Zn和异价元素Ag,实现了声子和载流子的输运性能优化.首先,体系YbMg2-xZnxSb2室温热导率从1.96 W m^-1K^-1降低至1.15 W m^-1K^-1,这是由于形成YbMg2Sb2-YbZn2Sb2的固溶体带来的合金化散射效应.其次,掺杂Ag可以增加载流子浓度,其数值在室温下从0.42×10^19cm^-3提升至7.72×10^19cm^-3,从而有效地提高了电导率和功率因子.通过综合两方面的协同效应使得体系zT在703 K时达到0.48,比纯样品YbMgZnSb2高60%.
基金supported by the National Natural Science Foundation of China(No.91438116)the Program for New Century Excellent Talents of China(No.NCET-12-0030)
文摘Radio Frequency(RF) technology represents a high-precision relative navigation solution that has significant potential for application to earth-orbiting satellites. In precision applications, multipath errors dominate the total error because observables, which are used to estimate carrier-phase integer ambiguity, are not always subject to a Gaussian distribution when dualfrequency ambiguity estimation methods are used in the presence of multipath. As it has been shown that ranging observables obey a Gaussian mixture distribution, this study proposes improvements to the accuracy of estimation based on multipath mitigation founded on the Gaussian mixture model. To this end, such a model is created for integer ambiguity resolution in the presence of multipath, using which the theoretical error in dual-frequency ambiguity estimation is derived.Expectation Maximization(EM), which aids dual-frequency ambiguity estimation, is subsequently proposed to reduce the effect of multipath errors. Finally, two experimental scenarios are implemented to test the performance of the proposed method. The results show that EM-aided dualfrequency ambiguity estimation reduces the range error to approximately 20% in comparison with simple dual-frequency ambiguity estimation. Therefore the proposed technique is effective for multipath mitigation in RF relative measurement.
基金The work was supported by National Basic Research Program of China(973 program,2013CB531500,to LY)the National Natural Science Foundation of China(81471624 to LY).
文摘CD4^(+)T cells are essential for sustaining CD8^(+)T cell responses during a chronic infection.The adoptive transfer of virus-specific CD4^(+)T cells has been shown to efficiently rescue exhausted CD8^(+)T cells.However,the question of whether endogenous virus-specific CD4^(+)T cell responses can be enhanced by certain vaccination strategies and subsequently reinvigorate exhausted CD8^(+)T cells remains unexplored.In this study,we developed a CD4^(+)T cell epitope-based heterologous prime-boost immunization strategy and examined the efficacy of this strategy using a mouse model of chronic lymphocytic choriomeningitis virus(LCMV)infection.We primed chronically LCMV-infected mice with a Listeria monocytogenes vector that expressed the LCMV glycoprotein-specific I-Ab-restricted CD4^(+)T cell epitope GP61–80(LM-GP61)and subsequently boosted the primed mice with an influenza virus A(PR8 strain)vector that expressed the same CD4^(+)T cell epitope(IAV-GP61).This heterologous prime-boost vaccination strategy elicited strong anti-viral CD4^(+)T cell responses,which further improved both the quantity and quality of the virusspecific CD8^(+)T cells and led to better control of the viral loads.The combination of this strategy and the blockade of the programmed cell death-1(PD-1)inhibitory pathway further enhanced the anti-viral CD8^(+)T cell responses and viral clearance.Thus,a heterologous prime-boost immunization that selectively induces virus-specific CD4^(+)T cell responses in conjunction with blockade of the inhibitory pathway may represent a promising therapeutic approach to treating patients with chronic viral infections.
基金supported in part by the China Huaneng Group Co.,Ltd.project“Research on the Optimization of Mid-long Term Electric Power Structure Transition of China Huaneng Group”(No.HNKJ20-H01)。
文摘Nuclear power development is a complex issue spanning cyber,physical,and social systems that is essential to achieving energy security and climate goals.With the ongoing worldwide trend towards carbon neutrality,the positioning of nuclear power in energy mix should be reconsidered.This paper aims to present a systematic review of current research on optimization of nuclear power development.The concept of cyber-physical-social system in energy(CPSSE)is adopted,which provides a suitable perspective and enables the review of relevant studies to achieve some novel insights.Based on the CPSSE,firstly,a research framework is established and the main research elements in optimization are identified,followed by a proposed conceptual risk-based optimization model.Secondly,current studies are analyzed and classified into four categories according to the research boundary.The status quo and limitations are discussed.It is found that the research results of nuclear-specific issues have not been well integrated into the optimization of nuclear power.As a relatively reliable power supply,nuclear power is capable of maintaining power and electricity adequacy of the whole system,especially in the case of power shortage caused by long-period low output of renewable energy or extreme external disasters.This superiority should not be ignored in the optimization.Other critical factors that should be further considered include disruptive technologies,nuclear safety,energy policies,and stakeholder behaviors.Finally,suggestions are given for future research.
基金The work was financially supported by the National Natural Science Foundation of China(No.51871077)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515012626)+3 种基金the Shenzhen Knowledge Innovation Plan-Fundamental Research(Discipline Distribution)(No.JCYJ20180507184623297)the Shenzhen Science and Technology Plan-Technology Innovation(No.KQJSCX20180328165656256)the Development and Reform Commission of Shenzhen Municipality-Shenzhen R&D Center for Albased Hydrogen Hydrolysis Materials(No.ZX20190229)the Startup Foundation from Shenzhen and Startup Foundation from Harbin Institute of Technology(Shenzhen).
文摘The contradiction between the strength and ductility of metallic materials is a major scientific problemthat has been researched for a long time. Dual-phase equiatomic and non-equiatomic Ti-Zr-Nb-Ta highentropy alloys (HEAs) with super-high strength and excellent ductility have been successfully developedvia mechanical alloying (MA) combined with spark plasma sintering (SPS) technology. This is adjustedby altering the atomic ratios of the different phases. X-ray diffraction (XRD) and transmission electronmicroscopy (TEM) were performed to confirm the dual-phase microstructure. After the SPS process, theaverage grain size of the aforementioned equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAs (134 ± 50 nm) evaluated byelectron back-scattering diffraction (EBSD) is smaller than that of the Ti-Zr-Nb-Ta HEAs (150 μm), whichwere fabricated using arc melting. According to the Hall-Petch formula, the grain boundary strengthening contribution in the Ti-Zr-Nb-Ta system is 33-fold higher than those fabricated using the arc-meltingprocess. When the alloy phase comprises the equivalent dual-phase, equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAshave good comprehensive performance compared to non-equiatomic Ti-Zr-Nb-Ta HEAs prepared usingthe same process. The yield strength of equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAs (2212 ± 38 MPa) is two-foldhigher than that of Ti-Zr-Nb-Ta HEAs (1100 ± 90 MPa) fabricated via arc melting. This can be attributed tothe ultra-fine grain size. Notably, the equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAs possess approximately the samebiocompatibility as commercial pure Ti (CP-Ti), indicating that the equiatomic Ti_(25)Zr_(25)Nb_(25)Ta_(25) HEAs areprovided with a possibility as an advanced biomaterial for the applications of the medical field.
基金supported by the National Natural Science Foun-dation of China(21875273 and 51872301)Natural Science Foundation of Zhejiang Province(LY18A040008)Youth Innovation Promotion Association of CAS(2019298).
文摘NaxCoO_(2)was known 20 years ago as a unique example in which spin entropy dominates the thermoelectric behavior.Hitherto,however,little has been learned about how to manipulate the spin degree of freedom in thermoelectrics.Here,we report the enhanced thermoelectric performance of GeMnTe_(2)by controlling the spin’s thermodynamic entropy.The anomalously large thermopower of GeMnTe_(2)is demonstrated to originate from the disordering of spin orientation under finite temperature.Based on the careful analysis of Heisenberg model,it is indicated that the spin-system entropy can be tuned by modifying the hybridization between Te-p and Mn-d orbitals.As a consequent strategy,Se doping enlarges the thermopower effectively,while neither carrier concentration nor band gap is affected.The measurement of magnetic susceptibility provides a solid evidence for the inherent relationship between the spin’s thermodynamic entropy and thermopower.By further introducing Bi doing,the maximum ZT in Ge_(0.94)Bi_(0.06)MnTe_(1.94)Se_(0.06)reaches 1.4 at 840 K,which is 45%higher than the previous report of Bi-doped GeMnTe_(2).This work reveals the high thermoelectric performance of GeMnTe_(2)and also provides an insightful understanding of the spin degree of freedom in thermoelectrics.
基金supported by grants from the National Natural Science Foundation of China(31872637 to Y.Z.and 31830106 to D.L.)NSF-IOS-1354434+1 种基金NSF-IOS-1339185NIH-GM132582 to S.P.D.-K.
文摘Protein–protein interaction(PPI)networks are key to nearly all aspects of cellular activity.Therefore,the identification of PPIs is important for understanding a specific biological process in an organism.Compared with conventional methods for probing PPIs,the recently described proximity labeling(PL)approach combined with mass spectrometry(MS)-based quantitative proteomics hasemerged as apowerful approach for characterizing PPIs.However,the application of PL in planta remains in its infancy.Here,we summarize recent progress in PL and its potential utilization in plant biology.We specifically summarize advances in PL,including the development and comparison of different PL enzymes and the application of PL for deciphering various molecular interactions in different organisms with an emphasis on plant systems.
基金supported by the National Natural Science Foundation of China(Nos.22179077,51774251,21908142)Shanghai Science and Technology Commission’s“2020 Science and Technology In-novation Action Plan”(No.20511104003)Natural Science Foundation in Shanghai(No.21ZR1424200)。
文摘O3-type layered oxide cathodes have been widely investigated due to their high reversible capacities and sufficient Na+reservoirs.However,such materials usually suffer from complex multistep phase transitions along with drastic volume changes,leading to the unsatisfied cycle performance.Herein,we report a Mg/Ti co-doped O3-type NaNi_(0.5)Mn_(0.5)O_(2),which can effectively suppress the complex multistep phase transition and realize a solid-solution reaction within a wide voltage range.It is confirmed that,the Mg/Ti co-doping is beneficial to enhance the structural stability and integrity by absorbing micro-strain and distortions.Thus,the as obtained sample delivers an outstanding cyclic performance(82.3%after 200 cycles at 1 C)in the voltage range of 2.0-4.0 V,and a high discharge capacity of 86.6 mAh/g after 100 cycles within the wide voltage range(2.0-4.5 V),which outperform the existing literatures.This co-doping strategy offers new insights into high performance O3-type cathode for sodium ion batteries.
