[Objectives] To analyze the low melting point fat constituents in the black soybeans with green and yellow heart and their relative content,and compare the differences in the low melting point fat constituents between...[Objectives] To analyze the low melting point fat constituents in the black soybeans with green and yellow heart and their relative content,and compare the differences in the low melting point fat constituents between different kinds of black soybeans. [Methods] Using HS-SPME-GC-MS,the qualitative analysis was performed on the low melting point fat constituents of black soybeans; using peak area normalization method,the relative content of constituents was calculated. [Results]A total of 42 peaks were identified from the low melting point fat constituents of the black soybeans with yellow heart,and 18 kinds of chemical constituents were identified,accounting for 81.39% of total relative content of low melting point fat constituents; a total of 37 peaks were identified from the low melting point fat constituents of the black soybeans with green heart,and 15 kinds of chemical constituents were identified,accounting for 83.24% of total relative content of low melting point fat constituents. There were 9 kinds of common chemical constituents for the two kinds of black soybeans,and 5-allylguaiacol had the highest relative content,followed by hexanol. [Conclusions] There was no significant difference in the low melting point fat constituents between two kinds of black soybeans.展开更多
Ultrasensitive molecular detection and quantization are crucial for many applications including clinical diagnostics,functional proteomics,and drug discovery;however,conventional biochemical sensors cannot satisfy the...Ultrasensitive molecular detection and quantization are crucial for many applications including clinical diagnostics,functional proteomics,and drug discovery;however,conventional biochemical sensors cannot satisfy the stringent requirements,and this has resulted in a long-standing dilemma regarding sensitivity improvement.To this end,we have developed an ultrasensitive relay-type nanomechanical sensor based on a magneto lever.By establishing the link between very weak molecular interaction and five orders of magnitude larger magnetic force,analytes at ultratrace level can produce a clearly observable mechanical response.Initially,proof-of-concept studies showed an improved detection limit up to five orders of magnitude when employing the magneto lever,as compared with direct detection using probe alone.In this study,we subsequently demonstrated that the relay-type sensing mode was universal in application ranging from micromolecule to macromolecule detection,which can be easily extended to detect enzymes,DNA,proteins,cells,viruses,bacteria,chemicals,etc.Importantly,we found that,sensitivity was no longer subject to probe affinity when the magneto lever was sufficiently high,theoretically,even reaching single-molecule resolution.展开更多
High-precision vibration frequency acquisition and 3D full-field modal analysis of key rotating components is crucial and has garnered significant attention from the engineering community.However,this requires both a ...High-precision vibration frequency acquisition and 3D full-field modal analysis of key rotating components is crucial and has garnered significant attention from the engineering community.However,this requires both a high sampling frequency to accurately capture vibration frequencies of rotating components and a high spatial resolution to enable full-field modal analysis,making it challenging to achieve both simultaneously when cost control is required.To address these limitations,this study introduces the Chinese remainder theorem(CRT)as the undersampling reconstruction technique and digital image correlation(DIC)to realize high-spatial resolution.Building on this,we propose a framework that integrates 3D DIC,operational modal analysis,modal assurance criterion,and a generalized robust CRT,to enable the decoupling and reconstruction of multi-tone vibration signals,along with full-field modal analysis for rotating structures.The proposed scheme is verified by a comparison experiment with laser Doppler velocimetry and then applied to the full-field undersampling vibration measurement of a rotating disc using low-speed cameras(50 fps).In the experiment,28 harmonic responses and 5 natural responses were identified,demonstrating the scheme's reliability and effectiveness.Furthermore,response frequencies up to 729.22 Hz(error<0.0426 Hz)are identified,and sub-micron amplitude resolution is realized.This method increases the measurement range by 28.32 times and furthermore provides detailed vibration model analysis,providing a cost-effective,high-resolution solution with broad applicability for monitoring rotating vibrations in critical equipment components.展开更多
The measurement of two-phase velocities in bubble flows using laser Doppler velocimetry(LDV)is studied.The key to the problem is to differentiate the LDV signals from bubbles and tracers,based on which the two-phase v...The measurement of two-phase velocities in bubble flows using laser Doppler velocimetry(LDV)is studied.The key to the problem is to differentiate the LDV signals from bubbles and tracers,based on which the two-phase velocities can be characterized.In this study,two experiments are carried out.Firstly,the bubble-chain experiment is performed to investigate the optical response of bubble surface and the corresponding LDV signal.The optical response shows that the light received by the LDV detector is dominated by the reflection component,which is similar to specular reflection to some extent.There are three typical patterns of signals of large bubbles passing through the measurement volume,all of which are with high amplitude and saturated.Then,the upward-flow experiment is conducted to study the statistical characteristics of large bubbles as well as micro tracers and micro bubbles.The results show that the amplitude of signal of millimeter bubbles is about an order of magnitude larger than that of tracers or micro bubbles.Based on this significant difference of the amplitude,we propose a phase discrimination method to distinguish two-phase signals.The capability of the proposed method is tested in a complex bubble flow,and its reliability is verified by bubble tracking velocimetry(BTV)technology.展开更多
文摘[Objectives] To analyze the low melting point fat constituents in the black soybeans with green and yellow heart and their relative content,and compare the differences in the low melting point fat constituents between different kinds of black soybeans. [Methods] Using HS-SPME-GC-MS,the qualitative analysis was performed on the low melting point fat constituents of black soybeans; using peak area normalization method,the relative content of constituents was calculated. [Results]A total of 42 peaks were identified from the low melting point fat constituents of the black soybeans with yellow heart,and 18 kinds of chemical constituents were identified,accounting for 81.39% of total relative content of low melting point fat constituents; a total of 37 peaks were identified from the low melting point fat constituents of the black soybeans with green heart,and 15 kinds of chemical constituents were identified,accounting for 83.24% of total relative content of low melting point fat constituents. There were 9 kinds of common chemical constituents for the two kinds of black soybeans,and 5-allylguaiacol had the highest relative content,followed by hexanol. [Conclusions] There was no significant difference in the low melting point fat constituents between two kinds of black soybeans.
基金supported by the National Natural Science Foundation of China(Nos.11627803,12072339,and 32061160475)USTC Research Funds of the Double First-Class Initiative(No.YD2480002003).
文摘Ultrasensitive molecular detection and quantization are crucial for many applications including clinical diagnostics,functional proteomics,and drug discovery;however,conventional biochemical sensors cannot satisfy the stringent requirements,and this has resulted in a long-standing dilemma regarding sensitivity improvement.To this end,we have developed an ultrasensitive relay-type nanomechanical sensor based on a magneto lever.By establishing the link between very weak molecular interaction and five orders of magnitude larger magnetic force,analytes at ultratrace level can produce a clearly observable mechanical response.Initially,proof-of-concept studies showed an improved detection limit up to five orders of magnitude when employing the magneto lever,as compared with direct detection using probe alone.In this study,we subsequently demonstrated that the relay-type sensing mode was universal in application ranging from micromolecule to macromolecule detection,which can be easily extended to detect enzymes,DNA,proteins,cells,viruses,bacteria,chemicals,etc.Importantly,we found that,sensitivity was no longer subject to probe affinity when the magneto lever was sufficiently high,theoretically,even reaching single-molecule resolution.
基金supported by the National Science Foundation for Young Scientists of China(Grant No.12402220)the National Natural Science Foundation of China(Grant No.12232017)the National Science and Technology Major Project(Grant No.J2019-V-0006-0100)。
文摘High-precision vibration frequency acquisition and 3D full-field modal analysis of key rotating components is crucial and has garnered significant attention from the engineering community.However,this requires both a high sampling frequency to accurately capture vibration frequencies of rotating components and a high spatial resolution to enable full-field modal analysis,making it challenging to achieve both simultaneously when cost control is required.To address these limitations,this study introduces the Chinese remainder theorem(CRT)as the undersampling reconstruction technique and digital image correlation(DIC)to realize high-spatial resolution.Building on this,we propose a framework that integrates 3D DIC,operational modal analysis,modal assurance criterion,and a generalized robust CRT,to enable the decoupling and reconstruction of multi-tone vibration signals,along with full-field modal analysis for rotating structures.The proposed scheme is verified by a comparison experiment with laser Doppler velocimetry and then applied to the full-field undersampling vibration measurement of a rotating disc using low-speed cameras(50 fps).In the experiment,28 harmonic responses and 5 natural responses were identified,demonstrating the scheme's reliability and effectiveness.Furthermore,response frequencies up to 729.22 Hz(error<0.0426 Hz)are identified,and sub-micron amplitude resolution is realized.This method increases the measurement range by 28.32 times and furthermore provides detailed vibration model analysis,providing a cost-effective,high-resolution solution with broad applicability for monitoring rotating vibrations in critical equipment components.
基金Project supported by the State Key Program of National Natural Science of China(Grant No.91852204)supported by the Program of State Key Laboratory of Marine Equipment(Grant No.SKLMEA-K201910).
文摘The measurement of two-phase velocities in bubble flows using laser Doppler velocimetry(LDV)is studied.The key to the problem is to differentiate the LDV signals from bubbles and tracers,based on which the two-phase velocities can be characterized.In this study,two experiments are carried out.Firstly,the bubble-chain experiment is performed to investigate the optical response of bubble surface and the corresponding LDV signal.The optical response shows that the light received by the LDV detector is dominated by the reflection component,which is similar to specular reflection to some extent.There are three typical patterns of signals of large bubbles passing through the measurement volume,all of which are with high amplitude and saturated.Then,the upward-flow experiment is conducted to study the statistical characteristics of large bubbles as well as micro tracers and micro bubbles.The results show that the amplitude of signal of millimeter bubbles is about an order of magnitude larger than that of tracers or micro bubbles.Based on this significant difference of the amplitude,we propose a phase discrimination method to distinguish two-phase signals.The capability of the proposed method is tested in a complex bubble flow,and its reliability is verified by bubble tracking velocimetry(BTV)technology.
