FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segrega...FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segregation problem in HEAs and pre-pare uniform HEA coatings.Scanning electron microscopy,transmission electron microscopy,and X-ray diffractometry were employed to characterize these coatings’microstructure and phase composition.The hardness,elastic modulus,and fracture toughness of coatings were tested,and the corrosion resistance was analyzed in simulated seawater.Results show that the hardness of the coating is HV0.1606.15,the modulus of elasticity is 128.42 GPa,and the fracture toughness is 43.98 MPa·m^(1/2).The corrosion potential of the coating in 3.5wt%NaCl solution is-0.49 V,and the corrosion current density is 1.2×10^(−6)A/cm^(2).The electrochemical system comprises three parts:the electrolyte,the adsorption and metallic oxide films produced during immersion,and the FeCoNiCrMo HEA coating.Over in-creasingly long periods,the corrosion reaction rate increases first and then decreases,the corrosion product film comprising metal oxides reaches a dynamic balance between formation and dissolution,and the internal reaction of the coating declines.展开更多
Several types of acoustic metamaterials composed of resonant units have been developed to achieve low-frequency bandgaps.In most of these structures,bandgaps are determined by their geometric configurations and materi...Several types of acoustic metamaterials composed of resonant units have been developed to achieve low-frequency bandgaps.In most of these structures,bandgaps are determined by their geometric configurations and material properties.This paper presents a frequency-displacement feedback control method for vibration suppression in a sandwich-like acoustic metamaterial plate.The band structure is theoretically derived using the Hamilton principle and validated by comparing the theoretical calculation results with the finite element simulation results.In this method,the feedback voltage is related to the displacement of a resonator and the excitation frequency.By applying a feedback voltage on the piezoelectric fiber-reinforced composite(PFRC)layers attached to a cantilever-mass resonator,the natural frequency of the resonator can be adjusted.It ensures that the bandgap moves in a frequency-dependent manner to keep the excitation frequency within the bandgap.Based on this frequency-displacement feedback control strategy,the bandgap of the metamaterial plate can be effectively adjusted,and the vibration of the metamaterial plate can be significantly suppressed.展开更多
As Moore’s law deteriorates,the research and development of new materials system are crucial for transitioning into the post Moore era.Traditional semiconductor materials,such as silicon,have served as the cornerston...As Moore’s law deteriorates,the research and development of new materials system are crucial for transitioning into the post Moore era.Traditional semiconductor materials,such as silicon,have served as the cornerstone of modern technologies for over half a century.This has been due to extensive research and engineering on new techniques to continuously enrich silicon-based materials system and,subsequently,to develop better performed silicon-based devices.Meanwhile,in the emerging post Moore era,layered semiconductor materials,such as transition metal dichalcogenides(TMDs),have garnered considerable research interest due to their unique electronic and optoelectronic properties,which hold great promise for powering the new era of next generation electronics.As a result,techniques for engineering the properties of layered semiconductors have expanded the possibilities of layered semiconductor-based devices.However,there remain significant limitations in the synthesis and engineering of layered semiconductors,impeding the utilization of layered semiconductor-based devices for mass applications.As a practical alternative,heterogeneous integration between layered and traditional semiconductors provides valuable opportunities to combine the distinctive properties of layered semiconductors with well-developed traditional semiconductors materials system.Here,we provide an overview of the comparative coherence between layered and traditional semiconductors,starting with TMDs as the representation of layered semiconductors.We highlight the meaningful opportunities presented by the heterogeneous integration of layered semiconductors with traditional semiconductors,representing an optimal strategy poised to propel the emerging semiconductor research community and chip industry towards unprecedented advancements in the coming decades.展开更多
We evaluated the biomass and ergosterol content of Hericium erinaceus mycelium, and extracellular enzyme activities in H. erinaceus liquid culture following salicylic acid（SA） and methyl jasmonic acid（Me JA）supple...We evaluated the biomass and ergosterol content of Hericium erinaceus mycelium, and extracellular enzyme activities in H. erinaceus liquid culture following salicylic acid（SA） and methyl jasmonic acid（Me JA）supplementation. The optimal SA concentration was100 lmoláL-1, where the highest ergosterol content of 2.33 mgág-1was obtained following 6-day cultivation with100 lmoláL-1SA supplementation, and which was significantly higher than the unsupplemented control（p ／ 0.01）. Following 4-day supplementation with50 lmoláL-1Me JA, the highest ergosterol content obtained was 1.988 mgág-1, which was 25.8 % higher than the unsupplemented control. Our data indicate that SA and Me JA supplementation improves ergosterol content in H.erinaceus mycelium.展开更多
With the development of power systems, power grid within a control area becomes much more complicated due to increasing number of nodes and renewable energy interconnections. The role of power system control center is...With the development of power systems, power grid within a control area becomes much more complicated due to increasing number of nodes and renewable energy interconnections. The role of power system control center is more critical in maintaining system reliable and security operations. Latest developed information and communication technologies provide a platform to enhance the functions and performance of power system control center. Smart power dispatch concept will be the trend of future control center development. In this paper, we start from the human factors of control center design and propose operation indices to reduce the information presented to the system operator. The operation indices will be the important criteria in situation awareness of a power grid. Past, present, future and capability states of a power grid are also proposed to provide better visions to the operator of system conditions. The basic ideas of operation indices and operation states are discussed in the paper. In the end, the design factors for a power dispatch cockpit are discussed.展开更多
Terahertz(THz)emission spectroscopy(TES)has emerged as a highly effective and versatile technique for investigating the photoelectric properties of diverse materials and nonlinear physical processes in the past few de...Terahertz(THz)emission spectroscopy(TES)has emerged as a highly effective and versatile technique for investigating the photoelectric properties of diverse materials and nonlinear physical processes in the past few decades.Concurrently,research on two-dimensional(2D)materials has experienced substantial growth due to their atomically thin structures,exceptional mechanical and optoelectronic properties,and the potential for applications in flexible electronics,sensing,and nanoelectronics.Specifically,these materials offer advantages such as tunable bandgap,high carrier mobility,wideband optical absorption,and relatively short carrier lifetime.By applying TES to investigate the 2D materials,their interfaces and heterostructures,rich information about the interplay among photons,charges,phonons and spins can be unfolded,which provides fundamental understanding for future applications.Thus it is timely to review the nonlinear processes underlying THz emission in 2D materials including optical rectification,photon-drag,high-order harmonic generation and spin-to-charge conversion,showcasing the rich diversity of the TES employed to unravel the complex nature of these materials.Typical applications based on THz emissions,such as THz lasers,ultrafast imaging and biosensors,are also discussed.Step further,we analyzed the unique advantages of spintronic terahertz emitters and the future technological advancements in the development of new THz generation mechanisms leading to advanced THz sources characterized by wide bandwidth,high power and integration,suitable for industrial and commercial applications.The continuous advancement and integration of TES with the study of 2D materials and heterostructures promise to revolutionize research in different areas,including basic materials physics,novel optoelectronic devices,and chips for post-Moore’s era.展开更多
Unequal social media attention can lead to potentially uneven distribution of disaster-relief funds,resulting in long-term inequality among regions after disasters.This study aimed to measure inequalities in social me...Unequal social media attention can lead to potentially uneven distribution of disaster-relief funds,resulting in long-term inequality among regions after disasters.This study aimed to measure inequalities in social media attention to regions during disasters and explore the role of official media in reducing such inequality.This is performed by employing social media,official media,and official aggregated statistics regarding China's rainstorm disasters.Through a set of panel-data regressions and robustness tests,three main conclusions were drawn:(1)There were inequalities among regions regarding social media attention they received during rainstorm disasters.For disasters of the same magnitude,regions with low economic outcome per capita received less attention on social media.(2)Official media can reduce inequality in social media attention during disasters.Official media statements can encourage netizens to pay attention to disaster-stricken areas,and especially the overlooked underdeveloped areas.(3)Of all the measures taken by official media,timely,accurate,and open disclosure of disaster occurrences proved to be the most potent means of leveling the playing field in terms of social media attention;contrarily,promotional or booster-type messages proved futile in this regard.These findings revealed the vulnerabilities within social media landscapes that aff ect disaster relief response,shedding light on the role of official guidance in mitigating inequalities in social media attention during such crises.Our study advises social media stakeholders and policymakers on formulating more equitable crisis communication strategies to bridge the gap in social media attention and foster a more balanced and just relief process.展开更多
Rare earth elements(REEs)have been long applied in magnesium alloys,among which the mischmetal-containing WE43 alloy has already got the CE mark approval for clinical application.A considerable amount of REEs(7 wt%)is...Rare earth elements(REEs)have been long applied in magnesium alloys,among which the mischmetal-containing WE43 alloy has already got the CE mark approval for clinical application.A considerable amount of REEs(7 wt%)is needed in that multi-phased alloy to achieve a good combination of mechanical strength and corrosion resistance.However,the high complex RE addition accompanied with multiple second phases may bring the concern of biological hazards.Single-phased Mg-RE alloys with simpler compositions were proposed to improve the overall performance,i.e.,“Simpler alloy,better performance”.The single-phased microstructure can be successfully obtained with typical high-solubility REEs(Ho,Er or Lu)through traditional smelting,casting and extrusion in a wide compositional range.A good corrosion resistance with a macroscopically uniform corrosion mode was guaranteed by the homogeneously single-phased microstructure.The bimodal-grained structure with plenty of sub-grain microstructures allow us to minimize the RE addition to<1 wt%,without losing mechanical properties.The single-phased Mg-RE alloys show comparable mechanical properties to the clinically-proven Mg-based implants.They exhibited similar in-vitro and in-vivo performances(without local or systematic toxicity in SD-rats)compared to a high purity magnesium.In addition,metal elements in our single-phased alloys can be gradually excreted through the urinary system and digestive system,showing no consistent accumulation of RE in main organs,i.e.,less burden on organs.The novel concept in this study focuses on the simplification of Mg-RE based alloys for biomedical purpose,and other biodegradable metals with single-phased microstructures are expected to be explored.展开更多
Purpose Integrated positron emission tomography and magnetic resonance(PET/MR)is a multimodality imaging technology integrating PET and MR,which can reflect the anatomical structure and physiological function simultan...Purpose Integrated positron emission tomography and magnetic resonance(PET/MR)is a multimodality imaging technology integrating PET and MR,which can reflect the anatomical structure and physiological function simultaneously.With the development of this technology,PET/MR plays an increasingly important role in clinical diagnosis and treatment.This review would demonstrate the current state of the latest advancement of PET/MR detection technology.Methods In this review,some studies of PET/MR detection technology in motion artifact correction,time of flight,noise reduction,performance testing methods,and phantoms were summarized.Results and conclusions PET/MR is advancing rapidly in imaging technology and has achieved phased achievements.The performance testing results of different models prove that the integration of PET and MR does not affect the respective performance,and the performance testing phantom for PET/MR needs further development.展开更多
Dehydration of serine/threonine residues necessitates the activity of a dehydratase enzyme(domain)during the biosynthesis of RiPP.Recently,it was reported that dehydration in the thioviridamide pathway relies on a dis...Dehydration of serine/threonine residues necessitates the activity of a dehydratase enzyme(domain)during the biosynthesis of RiPP.Recently,it was reported that dehydration in the thioviridamide pathway relies on a distinct dehydratase complex that showcases the activities of a phosphotransferase TvaC for serine/threonine phosphorylation and a lyase TvaD for subsequent phosphate elimination.Herein,we report that dehydration reactions in the pathway of lantibiotic cacaoidin involves a similar dehydratase complex,CaoK/CaoY.Remarkably,this dehydratase complex exhibits flexible enzymatic activity and tolerates significant variations in its substrate peptide sequence.By binding with the leader peptide(LP)sequence of precursor peptide CaoA,the dehydration reactions proceed in a directional manner from the C-terminus of the core peptide(CP)to the N-terminus,and C-terminally truncated variants of CP are acceptable.We show that fusing CaoK to CaoY in a 1:1 molar ratio enables the resulting enzyme CaoYK to exert enhanced dehydration activity.CaoK binds with the LP to improve its own solubility and to ensure the phosphate transfer activity,while CaoY functions in a manner independently of LP.This work advances our understanding of the dehydration process during cacaoidin formation,and provides useful enzymes and methods for the studies of the rapidly emerging RiPPs.展开更多
It is well known that calcium oxide (CaO) has better catalytic efficiency than most heterogeneous catalysts in many transesterification reactions. However, the gradual deactivation problem prevents its large-scale app...It is well known that calcium oxide (CaO) has better catalytic efficiency than most heterogeneous catalysts in many transesterification reactions. However, the gradual deactivation problem prevents its large-scale application in industry. In this paper, the deactivation mechanism of CaO in a fixed-bed reactor is investigated based on the transesterification reaction of propylene carbonate and methanol. The leaching amount of CaO during the reaction was estimated by the concentration of Ca in the products. The pretreated and recovered catalysts were characterized by FT-IR, XRD, TG-MS and SEM-EDS. It is evident from experiments and characterization that the deactivation process of CaO is accompanied by the leaching of calcium species and the generation of CaCO3, which are also verified by DFT calculations. At high temperature and high weight hourly space velocity, the deactivation was attributed to the formation of dense CaCO3 shell, which prevents the contact between the feedstock and the active species inside.展开更多
The expression of CD44 was upregulated in some hematological malignancies and is associated with metastasis and prognosis. The ligation of CD44 with specific monoclonal antibodies can trigger terminal differentiation ...The expression of CD44 was upregulated in some hematological malignancies and is associated with metastasis and prognosis. The ligation of CD44 with specific monoclonal antibodies can trigger terminal differentiation of leukemic blasts in some subtypes, so it is probable to develop an anti-CD44 based differentiation therapy in leukemia. The effects of CD44 and its monoclonal antibodies are discussed in this review. Cellular ＆ Molecular Immunology.展开更多
Magnesium alloys have shown great potential for their use in the medical device field, due to the promising biodegradability. However, it remains a challenge to characterize the degradation behavior of the Mg alloys i...Magnesium alloys have shown great potential for their use in the medical device field, due to the promising biodegradability. However, it remains a challenge to characterize the degradation behavior of the Mg alloys in a quantitative manner. As such, controlling the degradation rate of the Mg alloys as per our needs is still hard, which greatly limits the practical application of the Mg alloys as a degradable biomaterial.This paper discussed a numerical model developed based on the diffusion theory, which can capture the experimental degradation behavior of the Mg alloys precisely. The numerical model is then implemented into a finite element scheme, where the model is calibrated with the data from our previous studies on the corrosion of the as-cast Mg-1 Ca and the as-rolled Mg-3 Ge binary alloys. The degradation behavior of a pin implant is predicted using the calibrated model to demonstrate the model’s capability. A standard flow is provided in a practical framework for obtaining the degradation behavior of any biomedical Mg alloys. This methodology was further verified via the comparison with enormous available experimental results. Lastly, the material parameters defined in this model were provided as a new kind of material property.展开更多
Bupleurum chinense is a genuine medicinal material in Shanxi Province,and planting B.chinense is one of the main sources for local farmers to increase their income.In B.chinense cultivation,wheat-B.chinense,maize-B.ch...Bupleurum chinense is a genuine medicinal material in Shanxi Province,and planting B.chinense is one of the main sources for local farmers to increase their income.In B.chinense cultivation,wheat-B.chinense,maize-B.chinense and soybean-B.chinense are commonly used as multiple cropping patterns.In the present study,we studied the effects of three different multiple cropping patterns on N,P and K levels of soil,photosynthetic parameters,agronomic characteristics,saikosaponin A,C and D contents,yield and economic benefits of B.chinense.The results showed that the soybean-B.chinense multiple cropping pattern was beneficial to the enrichment of N in the soil,thus promoting photosynthetic parameters,growth,saikosaponin accumulation,yield and economic benefits of B.chinense.It is suggested that soybean-B.chinense multiple cropping was an appropriate multiple cropping pattern for local cultivation of B.chinense.展开更多
Purpose To investigate the influence of different reconstruction techniques on the quantitative accuracy and image quality of PET/CT.Methods The NEMA NU2-2018 image quality phantom was scanned on a GE Discovery Elite ...Purpose To investigate the influence of different reconstruction techniques on the quantitative accuracy and image quality of PET/CT.Methods The NEMA NU2-2018 image quality phantom was scanned on a GE Discovery Elite PET/CT scanner and the spatial resolution was measured based on NEMA NU2 standard.The same raw data were reconstructed using five different algorithms:ordered subset expectation maximization(OSEM),OSEM with point spread function(PSF)modeling,OSEM with time-of-flight(TOF),OSEM with TOF and PSF,and filtered back-projection(FBP).The recovery coefficient(RC),contrast recovery coefficient(CRC),and contrast-to-noise ratio(CNR)were calculated for the six hot spheres,the percent background variability(PBV)and coefficient of variation(COV)were calculated for the background,and the residual error(RE)was calculated for lung insert in different image slices.Results The incorporation of PSF modeling showed the smallest transverse FWHM and FWTM at both 1 and 10 cm radical offsets.The combination of PSF modeling and TOF improved RCmean and CRC for all spheres and resulted in the highest ratings for the detectability of 10 mm spheres in human observer assessment.PSF modeling played a role in reducing the COV within the background region of interest and increasing the CNR of the spheres,and decreased background noise ratings in human observer assessment.Besides,TOF significantly reduced the RE in lung insert.Neither PSF modeling nor TOF had a significant effect on PBV.Compared to FBP,the OSEM algorithm showed significant advantages in PBV,COV,CNR and RE and human observer ratings of image quality,but worse results for RC_(max),RC_(mean) and CRC.Conclusions The integration of TOF and PSF modeling into the OSEM algorithm achieves improvements in both quantitative accuracy and image quality,providing distinct advantages.PSF modeling improves the spatial resolution and decreases the visual appearance of background noise.The OSEM algorithm shows significantly better image quality than the FBP algorithm but no distinct advantages concerning quantitative accuracy.展开更多
基金supported by the National Natural Natural Science Foundation of China(No.52271055)the Natural Science Foundation of Hebei Province,China(No.E2024202154).
文摘FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segregation problem in HEAs and pre-pare uniform HEA coatings.Scanning electron microscopy,transmission electron microscopy,and X-ray diffractometry were employed to characterize these coatings’microstructure and phase composition.The hardness,elastic modulus,and fracture toughness of coatings were tested,and the corrosion resistance was analyzed in simulated seawater.Results show that the hardness of the coating is HV0.1606.15,the modulus of elasticity is 128.42 GPa,and the fracture toughness is 43.98 MPa·m^(1/2).The corrosion potential of the coating in 3.5wt%NaCl solution is-0.49 V,and the corrosion current density is 1.2×10^(−6)A/cm^(2).The electrochemical system comprises three parts:the electrolyte,the adsorption and metallic oxide films produced during immersion,and the FeCoNiCrMo HEA coating.Over in-creasingly long periods,the corrosion reaction rate increases first and then decreases,the corrosion product film comprising metal oxides reaches a dynamic balance between formation and dissolution,and the internal reaction of the coating declines.
基金supported by the National Natural Science Foundation of China(Nos.12472007 and 12072084)the Fundamental Research Funds for the Central Universities of China。
文摘Several types of acoustic metamaterials composed of resonant units have been developed to achieve low-frequency bandgaps.In most of these structures,bandgaps are determined by their geometric configurations and material properties.This paper presents a frequency-displacement feedback control method for vibration suppression in a sandwich-like acoustic metamaterial plate.The band structure is theoretically derived using the Hamilton principle and validated by comparing the theoretical calculation results with the finite element simulation results.In this method,the feedback voltage is related to the displacement of a resonator and the excitation frequency.By applying a feedback voltage on the piezoelectric fiber-reinforced composite(PFRC)layers attached to a cantilever-mass resonator,the natural frequency of the resonator can be adjusted.It ensures that the bandgap moves in a frequency-dependent manner to keep the excitation frequency within the bandgap.Based on this frequency-displacement feedback control strategy,the bandgap of the metamaterial plate can be effectively adjusted,and the vibration of the metamaterial plate can be significantly suppressed.
基金supported by National Key R&D Program of China(2020YFB2008704)the National Natural Science Foundation of China(62004114 and 62174098)+1 种基金Beijing Municipal Science and Technology Commission(Z221100005822011)The Tsinghua-Foshan Innovation Special Fund(2021THFS0215)。
文摘As Moore’s law deteriorates,the research and development of new materials system are crucial for transitioning into the post Moore era.Traditional semiconductor materials,such as silicon,have served as the cornerstone of modern technologies for over half a century.This has been due to extensive research and engineering on new techniques to continuously enrich silicon-based materials system and,subsequently,to develop better performed silicon-based devices.Meanwhile,in the emerging post Moore era,layered semiconductor materials,such as transition metal dichalcogenides(TMDs),have garnered considerable research interest due to their unique electronic and optoelectronic properties,which hold great promise for powering the new era of next generation electronics.As a result,techniques for engineering the properties of layered semiconductors have expanded the possibilities of layered semiconductor-based devices.However,there remain significant limitations in the synthesis and engineering of layered semiconductors,impeding the utilization of layered semiconductor-based devices for mass applications.As a practical alternative,heterogeneous integration between layered and traditional semiconductors provides valuable opportunities to combine the distinctive properties of layered semiconductors with well-developed traditional semiconductors materials system.Here,we provide an overview of the comparative coherence between layered and traditional semiconductors,starting with TMDs as the representation of layered semiconductors.We highlight the meaningful opportunities presented by the heterogeneous integration of layered semiconductors with traditional semiconductors,representing an optimal strategy poised to propel the emerging semiconductor research community and chip industry towards unprecedented advancements in the coming decades.
基金supported by funding from the China Agriculture Research System(CARS-24)the Heilongjiang Province Outstanding Youth Science Fund(JC201316)
文摘We evaluated the biomass and ergosterol content of Hericium erinaceus mycelium, and extracellular enzyme activities in H. erinaceus liquid culture following salicylic acid（SA） and methyl jasmonic acid（Me JA）supplementation. The optimal SA concentration was100 lmoláL-1, where the highest ergosterol content of 2.33 mgág-1was obtained following 6-day cultivation with100 lmoláL-1SA supplementation, and which was significantly higher than the unsupplemented control（p ／ 0.01）. Following 4-day supplementation with50 lmoláL-1Me JA, the highest ergosterol content obtained was 1.988 mgág-1, which was 25.8 % higher than the unsupplemented control. Our data indicate that SA and Me JA supplementation improves ergosterol content in H.erinaceus mycelium.
文摘With the development of power systems, power grid within a control area becomes much more complicated due to increasing number of nodes and renewable energy interconnections. The role of power system control center is more critical in maintaining system reliable and security operations. Latest developed information and communication technologies provide a platform to enhance the functions and performance of power system control center. Smart power dispatch concept will be the trend of future control center development. In this paper, we start from the human factors of control center design and propose operation indices to reduce the information presented to the system operator. The operation indices will be the important criteria in situation awareness of a power grid. Past, present, future and capability states of a power grid are also proposed to provide better visions to the operator of system conditions. The basic ideas of operation indices and operation states are discussed in the paper. In the end, the design factors for a power dispatch cockpit are discussed.
基金the National Key Research and Development Program of China(2021YFA1200800)the National Natural Science Foundation of China(62004114 and 62174098)Tsinghua University Initiative Scientific Research Center,Beijing Municipal Science and Technology Commission(Z221100005822011)and Beijing Advanced Innovation Center.
文摘Terahertz(THz)emission spectroscopy(TES)has emerged as a highly effective and versatile technique for investigating the photoelectric properties of diverse materials and nonlinear physical processes in the past few decades.Concurrently,research on two-dimensional(2D)materials has experienced substantial growth due to their atomically thin structures,exceptional mechanical and optoelectronic properties,and the potential for applications in flexible electronics,sensing,and nanoelectronics.Specifically,these materials offer advantages such as tunable bandgap,high carrier mobility,wideband optical absorption,and relatively short carrier lifetime.By applying TES to investigate the 2D materials,their interfaces and heterostructures,rich information about the interplay among photons,charges,phonons and spins can be unfolded,which provides fundamental understanding for future applications.Thus it is timely to review the nonlinear processes underlying THz emission in 2D materials including optical rectification,photon-drag,high-order harmonic generation and spin-to-charge conversion,showcasing the rich diversity of the TES employed to unravel the complex nature of these materials.Typical applications based on THz emissions,such as THz lasers,ultrafast imaging and biosensors,are also discussed.Step further,we analyzed the unique advantages of spintronic terahertz emitters and the future technological advancements in the development of new THz generation mechanisms leading to advanced THz sources characterized by wide bandwidth,high power and integration,suitable for industrial and commercial applications.The continuous advancement and integration of TES with the study of 2D materials and heterostructures promise to revolutionize research in different areas,including basic materials physics,novel optoelectronic devices,and chips for post-Moore’s era.
基金supported by the China Postdoctoral Science Foundation(2023M730284)the National Social Science Foundation of China(20BJY178)+1 种基金the National Natural Science Foundation of China(42301185)the Fundamental Research Funds for the Central Universities(2022NTST17)。
文摘Unequal social media attention can lead to potentially uneven distribution of disaster-relief funds,resulting in long-term inequality among regions after disasters.This study aimed to measure inequalities in social media attention to regions during disasters and explore the role of official media in reducing such inequality.This is performed by employing social media,official media,and official aggregated statistics regarding China's rainstorm disasters.Through a set of panel-data regressions and robustness tests,three main conclusions were drawn:(1)There were inequalities among regions regarding social media attention they received during rainstorm disasters.For disasters of the same magnitude,regions with low economic outcome per capita received less attention on social media.(2)Official media can reduce inequality in social media attention during disasters.Official media statements can encourage netizens to pay attention to disaster-stricken areas,and especially the overlooked underdeveloped areas.(3)Of all the measures taken by official media,timely,accurate,and open disclosure of disaster occurrences proved to be the most potent means of leveling the playing field in terms of social media attention;contrarily,promotional or booster-type messages proved futile in this regard.These findings revealed the vulnerabilities within social media landscapes that aff ect disaster relief response,shedding light on the role of official guidance in mitigating inequalities in social media attention during such crises.Our study advises social media stakeholders and policymakers on formulating more equitable crisis communication strategies to bridge the gap in social media attention and foster a more balanced and just relief process.
基金This work was supported by the National Key R&D Program of China(Grant No.2021YFC2400700),the National Natural Science Foundation of China(Grant No.52101283)the Science and Technology Planning Project of Guangzhou(Grant No.202201011454)+1 种基金the NSFC Incubation Program of GDPH(Grant No.KY012021165)the High-level Hospital Construction Project(Grant No.KJ012019520).
文摘Rare earth elements(REEs)have been long applied in magnesium alloys,among which the mischmetal-containing WE43 alloy has already got the CE mark approval for clinical application.A considerable amount of REEs(7 wt%)is needed in that multi-phased alloy to achieve a good combination of mechanical strength and corrosion resistance.However,the high complex RE addition accompanied with multiple second phases may bring the concern of biological hazards.Single-phased Mg-RE alloys with simpler compositions were proposed to improve the overall performance,i.e.,“Simpler alloy,better performance”.The single-phased microstructure can be successfully obtained with typical high-solubility REEs(Ho,Er or Lu)through traditional smelting,casting and extrusion in a wide compositional range.A good corrosion resistance with a macroscopically uniform corrosion mode was guaranteed by the homogeneously single-phased microstructure.The bimodal-grained structure with plenty of sub-grain microstructures allow us to minimize the RE addition to<1 wt%,without losing mechanical properties.The single-phased Mg-RE alloys show comparable mechanical properties to the clinically-proven Mg-based implants.They exhibited similar in-vitro and in-vivo performances(without local or systematic toxicity in SD-rats)compared to a high purity magnesium.In addition,metal elements in our single-phased alloys can be gradually excreted through the urinary system and digestive system,showing no consistent accumulation of RE in main organs,i.e.,less burden on organs.The novel concept in this study focuses on the simplification of Mg-RE based alloys for biomedical purpose,and other biodegradable metals with single-phased microstructures are expected to be explored.
文摘Purpose Integrated positron emission tomography and magnetic resonance(PET/MR)is a multimodality imaging technology integrating PET and MR,which can reflect the anatomical structure and physiological function simultaneously.With the development of this technology,PET/MR plays an increasingly important role in clinical diagnosis and treatment.This review would demonstrate the current state of the latest advancement of PET/MR detection technology.Methods In this review,some studies of PET/MR detection technology in motion artifact correction,time of flight,noise reduction,performance testing methods,and phantoms were summarized.Results and conclusions PET/MR is advancing rapidly in imaging technology and has achieved phased achievements.The performance testing results of different models prove that the integration of PET and MR does not affect the respective performance,and the performance testing phantom for PET/MR needs further development.
基金supported in part by grants from the National Key Research and Development Program of China(2022YFC2303100 for L.P and W.L)the National Natural Science Foundation of China(32030002 and 22193070 for W.L)+1 种基金the Science and Technology Commission of Shanghai Municipality(20XD1425200 for L.P)the CAS Youth Interdisciplinary Team(JCTD-2022-10 for L.P).
文摘Dehydration of serine/threonine residues necessitates the activity of a dehydratase enzyme(domain)during the biosynthesis of RiPP.Recently,it was reported that dehydration in the thioviridamide pathway relies on a distinct dehydratase complex that showcases the activities of a phosphotransferase TvaC for serine/threonine phosphorylation and a lyase TvaD for subsequent phosphate elimination.Herein,we report that dehydration reactions in the pathway of lantibiotic cacaoidin involves a similar dehydratase complex,CaoK/CaoY.Remarkably,this dehydratase complex exhibits flexible enzymatic activity and tolerates significant variations in its substrate peptide sequence.By binding with the leader peptide(LP)sequence of precursor peptide CaoA,the dehydration reactions proceed in a directional manner from the C-terminus of the core peptide(CP)to the N-terminus,and C-terminally truncated variants of CP are acceptable.We show that fusing CaoK to CaoY in a 1:1 molar ratio enables the resulting enzyme CaoYK to exert enhanced dehydration activity.CaoK binds with the LP to improve its own solubility and to ensure the phosphate transfer activity,while CaoY functions in a manner independently of LP.This work advances our understanding of the dehydration process during cacaoidin formation,and provides useful enzymes and methods for the studies of the rapidly emerging RiPPs.
基金supported by the Liaoning Provincial Natural Science Foundation Joint Fund for Innovation Capability Improvement(2021-NLTS-12-02)Key Research and Local Service Projects of the Liaoning Provincial Department of Education(LDB2019005).
文摘It is well known that calcium oxide (CaO) has better catalytic efficiency than most heterogeneous catalysts in many transesterification reactions. However, the gradual deactivation problem prevents its large-scale application in industry. In this paper, the deactivation mechanism of CaO in a fixed-bed reactor is investigated based on the transesterification reaction of propylene carbonate and methanol. The leaching amount of CaO during the reaction was estimated by the concentration of Ca in the products. The pretreated and recovered catalysts were characterized by FT-IR, XRD, TG-MS and SEM-EDS. It is evident from experiments and characterization that the deactivation process of CaO is accompanied by the leaching of calcium species and the generation of CaCO3, which are also verified by DFT calculations. At high temperature and high weight hourly space velocity, the deactivation was attributed to the formation of dense CaCO3 shell, which prevents the contact between the feedstock and the active species inside.
文摘The expression of CD44 was upregulated in some hematological malignancies and is associated with metastasis and prognosis. The ligation of CD44 with specific monoclonal antibodies can trigger terminal differentiation of leukemic blasts in some subtypes, so it is probable to develop an anti-CD44 based differentiation therapy in leukemia. The effects of CD44 and its monoclonal antibodies are discussed in this review. Cellular ＆ Molecular Immunology.
基金supported by National Key Research and Development Program of China (Grant No. 2016YFC1102402)National Natural Science Foundation of China (Grant No. 51431002 and 51871004)+1 种基金NSFC/RGC Joint Research Scheme (Grant No. 51661165014)Peking University Medicine Seed Fund for Interdisciplinary Research (Grant No. BMU2018ME005)
文摘Magnesium alloys have shown great potential for their use in the medical device field, due to the promising biodegradability. However, it remains a challenge to characterize the degradation behavior of the Mg alloys in a quantitative manner. As such, controlling the degradation rate of the Mg alloys as per our needs is still hard, which greatly limits the practical application of the Mg alloys as a degradable biomaterial.This paper discussed a numerical model developed based on the diffusion theory, which can capture the experimental degradation behavior of the Mg alloys precisely. The numerical model is then implemented into a finite element scheme, where the model is calibrated with the data from our previous studies on the corrosion of the as-cast Mg-1 Ca and the as-rolled Mg-3 Ge binary alloys. The degradation behavior of a pin implant is predicted using the calibrated model to demonstrate the model’s capability. A standard flow is provided in a practical framework for obtaining the degradation behavior of any biomedical Mg alloys. This methodology was further verified via the comparison with enormous available experimental results. Lastly, the material parameters defined in this model were provided as a new kind of material property.
基金National Natural Science Foundation of China(Grant No.31601677)Natural Science Foundation of Shanxi Province(Grant No.201701D121180)+1 种基金Key Research and Development Project of Jinzhong City in Shanxi Province(Grant No.Y182018)Technological innovation team of development and utilization Chinese Geoherbs Resources in Shanxi Province,China(No.2018TD009)。
文摘Bupleurum chinense is a genuine medicinal material in Shanxi Province,and planting B.chinense is one of the main sources for local farmers to increase their income.In B.chinense cultivation,wheat-B.chinense,maize-B.chinense and soybean-B.chinense are commonly used as multiple cropping patterns.In the present study,we studied the effects of three different multiple cropping patterns on N,P and K levels of soil,photosynthetic parameters,agronomic characteristics,saikosaponin A,C and D contents,yield and economic benefits of B.chinense.The results showed that the soybean-B.chinense multiple cropping pattern was beneficial to the enrichment of N in the soil,thus promoting photosynthetic parameters,growth,saikosaponin accumulation,yield and economic benefits of B.chinense.It is suggested that soybean-B.chinense multiple cropping was an appropriate multiple cropping pattern for local cultivation of B.chinense.
文摘Purpose To investigate the influence of different reconstruction techniques on the quantitative accuracy and image quality of PET/CT.Methods The NEMA NU2-2018 image quality phantom was scanned on a GE Discovery Elite PET/CT scanner and the spatial resolution was measured based on NEMA NU2 standard.The same raw data were reconstructed using five different algorithms:ordered subset expectation maximization(OSEM),OSEM with point spread function(PSF)modeling,OSEM with time-of-flight(TOF),OSEM with TOF and PSF,and filtered back-projection(FBP).The recovery coefficient(RC),contrast recovery coefficient(CRC),and contrast-to-noise ratio(CNR)were calculated for the six hot spheres,the percent background variability(PBV)and coefficient of variation(COV)were calculated for the background,and the residual error(RE)was calculated for lung insert in different image slices.Results The incorporation of PSF modeling showed the smallest transverse FWHM and FWTM at both 1 and 10 cm radical offsets.The combination of PSF modeling and TOF improved RCmean and CRC for all spheres and resulted in the highest ratings for the detectability of 10 mm spheres in human observer assessment.PSF modeling played a role in reducing the COV within the background region of interest and increasing the CNR of the spheres,and decreased background noise ratings in human observer assessment.Besides,TOF significantly reduced the RE in lung insert.Neither PSF modeling nor TOF had a significant effect on PBV.Compared to FBP,the OSEM algorithm showed significant advantages in PBV,COV,CNR and RE and human observer ratings of image quality,but worse results for RC_(max),RC_(mean) and CRC.Conclusions The integration of TOF and PSF modeling into the OSEM algorithm achieves improvements in both quantitative accuracy and image quality,providing distinct advantages.PSF modeling improves the spatial resolution and decreases the visual appearance of background noise.The OSEM algorithm shows significantly better image quality than the FBP algorithm but no distinct advantages concerning quantitative accuracy.
