To investigate the thermal stability of ceramic-matrix composites,three kinds of C/C−ZrC−SiC composites with different Zr/Si molar ratios were synthesized by reactive melt infiltration.Employing region labeling method...To investigate the thermal stability of ceramic-matrix composites,three kinds of C/C−ZrC−SiC composites with different Zr/Si molar ratios were synthesized by reactive melt infiltration.Employing region labeling method,the high-temperature thermal stability of the composites was systematically studied by changing the temperature and holding time of thermal treatment.Results show that the mass loss rate of low Si composites has a growth trend with increasing temperature,and a crystal transformation from β-SiC toα-SiC occurs in the composites.In the calibrated area,SiC phase experiences Ostwald ripening and volume change with location migration,while ZrC phase experiences a re-sintering process with diffusion.Moreover,it is found that increasing temperature has a more obvious effect on the thermal stability than extending holding time,which is mainly attributed to the faster diffusion rate of atoms.展开更多
Objective The present study aimed to evaluate the accuracy of the factorial method for estimating energy needs in individuals living in China.Methods Sixteen healthy female adults aged 22.1±1.2 years with a body ...Objective The present study aimed to evaluate the accuracy of the factorial method for estimating energy needs in individuals living in China.Methods Sixteen healthy female adults aged 22.1±1.2 years with a body mass index （kg/m 2） of 20.4±1.7 were selected as subjects.In free-living conditions,energy expenditure （EE） was determined by using the factorial method.At the same time,the doubly labeled water method （DLW） was also used to measure energy expenditure of the subjects and served as the criterion method.EE predicted by the factorial method （EE factorial） was compared with the simultaneous measurement of EE by the validated DLW method （EE DLW）.Results There was excellent agreement between EE factorial （7.46±0.59 MJ/d） and EE DLW （7.64 ± 0.49 MJ/d）,with a difference of-2.6±4.9% （-0.18±0.36 MJ/d）.No significant differences were found between the two methods.EE factorial was highly correlated with EE DLW （r=0.795,P0.001） and a good agreement for individuals was found by using the Bland and Altman test.Conclusion The factorial method gives satisfactory estimates of EE for both groups and individuals living in China.展开更多
Recent advances in utilizing ^(17)O isotopic labeling methods for solid-state nuclear magnetic resonance(NMR)investigations of metal oxides for lithium-ion batteries have yielded extensive insights into their structur...Recent advances in utilizing ^(17)O isotopic labeling methods for solid-state nuclear magnetic resonance(NMR)investigations of metal oxides for lithium-ion batteries have yielded extensive insights into their structural and dynamic details.Herein,we commence with a brief introduction to recent research on lithium-ion battery oxide materials studied using ^(17)O solid-state NMR spectroscopy.Then we delve into a review of ^(17)O isotopic labeling methods for tagging oxygen sites in both the bulk and surfaces of metal oxides.At last,the unresolved problems and the future research directions for advancing the ^(17)O labeling technique are discussed.展开更多
The precision and reliability of first-arrival picking are crucial for determining the accuracy of geological structure inversion using active source ocean bottom seismometer(OBS)refraction data.Traditional methods fo...The precision and reliability of first-arrival picking are crucial for determining the accuracy of geological structure inversion using active source ocean bottom seismometer(OBS)refraction data.Traditional methods for first-arrival picking based on sample points are characterized by theoretical errors,especially in low-sampling-frequency OBS data because the travel time of seismic waves is not an integer multiple of the sampling interval.In this paper,a first-arrival picking method that utilizes the spatial waveform variation characteristics of active source OBS data is presented.First,the distribution law of theoretical error is examined;adjacent traces exhibit variation characteristics in their waveforms.Second,a label cross-correlation superposition method for extracting highfrequency signals is presented to enhance the first-arrival picking precision.Results from synthetic and field data verify that the proposed approach is robust,successfully overcomes the limitations of low sampling frequency,and achieves precise outcomes that are comparable with those of high-sampling-frequency data.展开更多
In this study,we compared FeNi alloy magnetic nanoparticles(MNPs) prepared by either combustion or chemical precipitation methods.We found that the FeNi MNPs generated by combustion method have a rather high saturatio...In this study,we compared FeNi alloy magnetic nanoparticles(MNPs) prepared by either combustion or chemical precipitation methods.We found that the FeNi MNPs generated by combustion method have a rather high saturation magnetization Ms of ～180 emu/g and a coercivity field Hc of near zero.However,the alloy nanoparticles are easily aggregated and are not well dispersive such that size distribution of the nanoparticle clusters is wide and clusters are rather big(around 50～700 nm).To prepare a better quality and well dispersed Fe-Ni MNPs,we also developed a thermal reflux chemical precipitation method to synthesize FeNi3 alloy MNPs.The precursor chemicals of Fe(acac)3 and Ni(acac)2 in a molecular ratio of 1:3 reacted in octyl ether solvent at the boiling point of solvent(～300 ℃) by the thermal reflux process.The 1,2-hexadecandiol and tri-n-octylphosphine oxide(TOPO) were used as reducer and surfactant,respectively.The chemically precipitated FeNi3 MNPs are well dispersed and have well-controlled particle sizes around 10～20 nm with a very narrow size distribution(±1.2 nm).The highly monodispersive FeNi3 MNPs present good uniformity in particle shape and crystallinity on particle surfaces.The MNPs exhibit well soft magnetism with saturation magnetization of ～61 emu/g and Hc～0.The biomedically compatible FeNi MNPs which were coated with biocompatible polyethyleneimine(PEI) polymer were also synthesized.We demonstrated that the PEI coated FeNi MNPs can enter the mammalian cells in vitro and can be used as a magnetic resonance imagine(MRI) contrast agent.The results demonstrated that FeNi MNPs potentially could be applied in the biomedical field.The functionalized magnetic beads with biocompatible polymer coated on MNPs are also completed for biomedical applications.展开更多
As the volume of Internet traffic continues to grow, there is a need for mechanisms that ensure communication quality that is suitable for different applications. OpenFlow implements per-flow routing control but can h...As the volume of Internet traffic continues to grow, there is a need for mechanisms that ensure communication quality that is suitable for different applications. OpenFlow implements per-flow routing control but can have adverse effects on communication quality when the number of flow entries is increased. In this study, we propose a routing method that controls traffic flows by labeling them with numbers representing the source switch, destination switch and required communication quality. The OpenFlow controller then sets up flow entries on a per-label basis rather than on a per-flow basis, allowing it to reduce the number of flow entries. In an evaluation test, we confirmed that the labeling method could prevent this reduction in communication quality.展开更多
基金supported by the National Natural Science Foundation of China(No.U19A2099)the CAS Key Laboratory of Carbon Materials,China(No.KLCMKFJJ2005)the Fund of Aerospace Research Institute of Material and Processing Technology,China(No.6142906200108).
文摘To investigate the thermal stability of ceramic-matrix composites,three kinds of C/C−ZrC−SiC composites with different Zr/Si molar ratios were synthesized by reactive melt infiltration.Employing region labeling method,the high-temperature thermal stability of the composites was systematically studied by changing the temperature and holding time of thermal treatment.Results show that the mass loss rate of low Si composites has a growth trend with increasing temperature,and a crystal transformation from β-SiC toα-SiC occurs in the composites.In the calibrated area,SiC phase experiences Ostwald ripening and volume change with location migration,while ZrC phase experiences a re-sintering process with diffusion.Moreover,it is found that increasing temperature has a more obvious effect on the thermal stability than extending holding time,which is mainly attributed to the faster diffusion rate of atoms.
基金supported by the National Natural Science Foundation of China (No. 30771811)the Scientific Research Foundation of Hebei Medical University for the Young Core Instructor (No. 30900143)
文摘Objective The present study aimed to evaluate the accuracy of the factorial method for estimating energy needs in individuals living in China.Methods Sixteen healthy female adults aged 22.1±1.2 years with a body mass index （kg/m 2） of 20.4±1.7 were selected as subjects.In free-living conditions,energy expenditure （EE） was determined by using the factorial method.At the same time,the doubly labeled water method （DLW） was also used to measure energy expenditure of the subjects and served as the criterion method.EE predicted by the factorial method （EE factorial） was compared with the simultaneous measurement of EE by the validated DLW method （EE DLW）.Results There was excellent agreement between EE factorial （7.46±0.59 MJ/d） and EE DLW （7.64 ± 0.49 MJ/d）,with a difference of-2.6±4.9% （-0.18±0.36 MJ/d）.No significant differences were found between the two methods.EE factorial was highly correlated with EE DLW （r=0.795,P0.001） and a good agreement for individuals was found by using the Bland and Altman test.Conclusion The factorial method gives satisfactory estimates of EE for both groups and individuals living in China.
基金supported by National Key R&D Program of China(2021YFA1502803)the National Natural Science Foundation of China(NSFC)(21972066,91745202)+3 种基金NSFC-Royal Society Joint Program(21661130149)L.P.thanks the Royal Society and Newton Fund for a Royal Society-Newton Advanced Fellowshipsupported by the Research Funds for the Frontiers Science Centre for Critical Earth Material Cycling,Nanjing Universitya Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Recent advances in utilizing ^(17)O isotopic labeling methods for solid-state nuclear magnetic resonance(NMR)investigations of metal oxides for lithium-ion batteries have yielded extensive insights into their structural and dynamic details.Herein,we commence with a brief introduction to recent research on lithium-ion battery oxide materials studied using ^(17)O solid-state NMR spectroscopy.Then we delve into a review of ^(17)O isotopic labeling methods for tagging oxygen sites in both the bulk and surfaces of metal oxides.At last,the unresolved problems and the future research directions for advancing the ^(17)O labeling technique are discussed.
基金supported by the Major Research Plan on West-Pacific Earth System Multispheric Interactions (Nos.91858215,91958206)the National Natural Science Foundation of China (NSFC)Shiptime Sharing Project (No.41949581)the Key Research and Development Program of Shandong Province (No.2019GHY112019)。
文摘The precision and reliability of first-arrival picking are crucial for determining the accuracy of geological structure inversion using active source ocean bottom seismometer(OBS)refraction data.Traditional methods for first-arrival picking based on sample points are characterized by theoretical errors,especially in low-sampling-frequency OBS data because the travel time of seismic waves is not an integer multiple of the sampling interval.In this paper,a first-arrival picking method that utilizes the spatial waveform variation characteristics of active source OBS data is presented.First,the distribution law of theoretical error is examined;adjacent traces exhibit variation characteristics in their waveforms.Second,a label cross-correlation superposition method for extracting highfrequency signals is presented to enhance the first-arrival picking precision.Results from synthetic and field data verify that the proposed approach is robust,successfully overcomes the limitations of low sampling frequency,and achieves precise outcomes that are comparable with those of high-sampling-frequency data.
文摘In this study,we compared FeNi alloy magnetic nanoparticles(MNPs) prepared by either combustion or chemical precipitation methods.We found that the FeNi MNPs generated by combustion method have a rather high saturation magnetization Ms of ～180 emu/g and a coercivity field Hc of near zero.However,the alloy nanoparticles are easily aggregated and are not well dispersive such that size distribution of the nanoparticle clusters is wide and clusters are rather big(around 50～700 nm).To prepare a better quality and well dispersed Fe-Ni MNPs,we also developed a thermal reflux chemical precipitation method to synthesize FeNi3 alloy MNPs.The precursor chemicals of Fe(acac)3 and Ni(acac)2 in a molecular ratio of 1:3 reacted in octyl ether solvent at the boiling point of solvent(～300 ℃) by the thermal reflux process.The 1,2-hexadecandiol and tri-n-octylphosphine oxide(TOPO) were used as reducer and surfactant,respectively.The chemically precipitated FeNi3 MNPs are well dispersed and have well-controlled particle sizes around 10～20 nm with a very narrow size distribution(±1.2 nm).The highly monodispersive FeNi3 MNPs present good uniformity in particle shape and crystallinity on particle surfaces.The MNPs exhibit well soft magnetism with saturation magnetization of ～61 emu/g and Hc～0.The biomedically compatible FeNi MNPs which were coated with biocompatible polyethyleneimine(PEI) polymer were also synthesized.We demonstrated that the PEI coated FeNi MNPs can enter the mammalian cells in vitro and can be used as a magnetic resonance imagine(MRI) contrast agent.The results demonstrated that FeNi MNPs potentially could be applied in the biomedical field.The functionalized magnetic beads with biocompatible polymer coated on MNPs are also completed for biomedical applications.
文摘As the volume of Internet traffic continues to grow, there is a need for mechanisms that ensure communication quality that is suitable for different applications. OpenFlow implements per-flow routing control but can have adverse effects on communication quality when the number of flow entries is increased. In this study, we propose a routing method that controls traffic flows by labeling them with numbers representing the source switch, destination switch and required communication quality. The OpenFlow controller then sets up flow entries on a per-label basis rather than on a per-flow basis, allowing it to reduce the number of flow entries. In an evaluation test, we confirmed that the labeling method could prevent this reduction in communication quality.
