Zwitterionic sulfobetaine-based monolithic stationary phases have attracted increasing attention for their use in hydrophilic interaction chromatography.In this study,a novel hydrophilic polymeric monolith was fabrica...Zwitterionic sulfobetaine-based monolithic stationary phases have attracted increasing attention for their use in hydrophilic interaction chromatography.In this study,a novel hydrophilic polymeric monolith was fabricated through photo-initiated copolymerization of 3-(3-vinyl-1-imidazolio)-1-propanesulfonate(SBVI)with pentaerythritol triacrylate using methanol and tetrahydrofuran as the porogenic system.Notably,the duration for the preparation of this novel monolith was as little as 5 min,which was significantly shorter than that required for previously reported sulfobetaine-based monoliths prepared via conventional thermally initiated copolymerization.Moreover,these monoliths showed good morphology,permeability,porosity(62.4%),mechanical strength(over 15 MPa),column efficiency(51,230 plates/m),and reproducibility(relative standard deviations for all analytes were lower than 4.6%).Mechanistic studies indicated that strong hydrophilic and negative electrostatic interactions might be responsible for the retention of polar analytes on the zwitterionic SBVI-based monolith.In particular,the resulting monolith exhibited good anti-protein adhesion ability and low nonspecific protein adsorption.These excellent features seem to favor its application in bioanalysis.Therefore,the novel zwitterionic sulfobetaine-based monolith was successfully employed for the highly selective separation of small bioactive compounds and the efficient enrichment of N-glycopeptides from complex samples.In this study,we prepared a novel zwitterionic sulfobetaine-based monolith with good performance and developed a simpler and faster method for preparation of zwitterionic monoliths.展开更多
The hydroarylation reaction of terminal alkynes with arylboronic acids catalyzed by low(400 ppm) loadings of palladium has been developed. The reaction is broad in scope and high-yielding, even on multigram scale. It ...The hydroarylation reaction of terminal alkynes with arylboronic acids catalyzed by low(400 ppm) loadings of palladium has been developed. The reaction is broad in scope and high-yielding, even on multigram scale. It is suitable for the synthesis of alkenes labeled with deuterium, and for the late-stage modification of bioactive molecules.展开更多
Continuous measurement of blood pressure based on pulse transit time (PTT) using GMR sensors is the state-of-art non-invasive cuffless method in which modulated magnetic signature of blood (MMSB) is used. In this pape...Continuous measurement of blood pressure based on pulse transit time (PTT) using GMR sensors is the state-of-art non-invasive cuffless method in which modulated magnetic signature of blood (MMSB) is used. In this paper, the mechanism of MMSB is investigated. According to the experimental results, it is found that both blood pulse flowing through the applied magnetic field and the displacement of the GMR sensor caused by blood pulse contribute to the disturbance of magnetic field detected by GMR sensors. The feasibility of MMSB method is discussed as well.展开更多
Continuous non-invasive blood pressure (BP) measurement can be realized by using pulse transit time (PTT) based on electrocardiogram (ECG) and pulse wave signal. Modulated magnetic signature of blood (MMSB) is a promi...Continuous non-invasive blood pressure (BP) measurement can be realized by using pulse transit time (PTT) based on electrocardiogram (ECG) and pulse wave signal. Modulated magnetic signature of blood (MMSB) is a promising approach to obtain PTT. The origin of MMSB is critical to establish the relationship between MMSB and BP. In this paper, two possible origins of MMSB, blood disturbance mechanism and angular variation mechanism, are analyzed and verified through three control experi-ments under different conditions. The influence of blood velocity alteration and blood volume alteration on magnetic field is investigated though blood flow simulation sys-tem. It is found that MMSB comes mainly from the periodic blood flow while the per-turbation caused by angular variation between sensitive axis of the magnetic sensor and geomagnetic field can be neglected. As to blood disturbance mechanism, the change of blood volume plays a decisive role while the effect of blood velocity altera-tion is negligible.展开更多
Piezoelectric MEMS loudspeakers based on cantilever diaphragms have demonstrated promising electroacoustic efficiency and low-frequency sound pressure level(SPL).However,their total harmonic distortion(THD)significant...Piezoelectric MEMS loudspeakers based on cantilever diaphragms have demonstrated promising electroacoustic efficiency and low-frequency sound pressure level(SPL).However,their total harmonic distortion(THD)significantly increases near the first resonant frequency,and high-frequency SPL(above 10 kHz)rapidly decreases due to the resonance frequency and bandwidth limitations,severely affecting sound quality.This work presents a piezoelectric MEMS loudspeaker featuring a 2.7μm-thick sputtered PZT film,comprising a cantilever diaphragm and four sets of Double-S actuators.The first resonance frequency of the cantilever diaphragm is 3.2 kHz,and the Double-S actuators introduce an additional resonance frequency at 21.3 kHz,addressing the issues of insufficient high-frequency SPL and poor THD performance.Testing on a 711-ear simulator reveals that,under 1-3 Vpp excitation,incorporating the Double-S actuators leads to an average SPL increase of 23 dB and an average THD reduction of 80%that remains below 0.6% across the 3.2-20 kHz range.Thus,both SPL and THD performance in the mid-to high-frequency range are improved.This work paves the way for the development of high-fidelity piezoelectric MEMS loudspeakers,offering new opportunities to improve sound quality and extend the frequency range for in-ear applications.展开更多
The attractive memristor is interpreted based on its constitutive relation.The memory property of the memristor is explained,along with the explanation on its three fingerprints：（1） Pinched hysteresis loop;（2） Hy...The attractive memristor is interpreted based on its constitutive relation.The memory property of the memristor is explained,along with the explanation on its three fingerprints：（1） Pinched hysteresis loop;（2） Hysteresis lobe area decreases as frequency increases;（3） Pinched hysteresis loop shrinks to a single-valued function at infinite frequency.Where the magnetic flux is in Strukov＇s memristor is also introduced.Resistive elements including the memristor are taken as an example to argue that the constitutive relation determines the electrical property of a circuit element and diagram method is used to distinguish different elements in the resistive element series.展开更多
The concept of the memristor was proposed by Leon Chua in 1971, along with some electro-magnetic interpretations according to quasi-static expansion of Maxwell＇s equations. In 2003, Chua included the memristor into a...The concept of the memristor was proposed by Leon Chua in 1971, along with some electro-magnetic interpretations according to quasi-static expansion of Maxwell＇s equations. In 2003, Chua included the memristor into a four-element torus that has infinite circuit elements. This paper uses the quasi-static method to interpret every circuit element in the torus. Two examples are also provided to show how topologic structure of an element affects its electrical properties by affecting the dominant electro-magnetic field components. Additionally, it is proved that the circuit elements in the torus, except the resistive, capacitive and inductive elements, cannot exist independently. Moreover, the incorrectness in Chua＇s interpretation of the memristor, that the memristor cannot be interpreted with the transient quasi-static method due to its memory property, is pointed out. Finally, the limitations of the electro-magnetic interpretation method are discussed.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.:82173773 and 82073806)the Natural Science Foundation of Guangdong Province,China(Grant Nos.:2020A1515010569 and 2021A0505030039)Science and Technology Program of Guangzhou,China(Grant No.:202102020729).
文摘Zwitterionic sulfobetaine-based monolithic stationary phases have attracted increasing attention for their use in hydrophilic interaction chromatography.In this study,a novel hydrophilic polymeric monolith was fabricated through photo-initiated copolymerization of 3-(3-vinyl-1-imidazolio)-1-propanesulfonate(SBVI)with pentaerythritol triacrylate using methanol and tetrahydrofuran as the porogenic system.Notably,the duration for the preparation of this novel monolith was as little as 5 min,which was significantly shorter than that required for previously reported sulfobetaine-based monoliths prepared via conventional thermally initiated copolymerization.Moreover,these monoliths showed good morphology,permeability,porosity(62.4%),mechanical strength(over 15 MPa),column efficiency(51,230 plates/m),and reproducibility(relative standard deviations for all analytes were lower than 4.6%).Mechanistic studies indicated that strong hydrophilic and negative electrostatic interactions might be responsible for the retention of polar analytes on the zwitterionic SBVI-based monolith.In particular,the resulting monolith exhibited good anti-protein adhesion ability and low nonspecific protein adsorption.These excellent features seem to favor its application in bioanalysis.Therefore,the novel zwitterionic sulfobetaine-based monolith was successfully employed for the highly selective separation of small bioactive compounds and the efficient enrichment of N-glycopeptides from complex samples.In this study,we prepared a novel zwitterionic sulfobetaine-based monolith with good performance and developed a simpler and faster method for preparation of zwitterionic monoliths.
基金financial support from the National Natural Science Foundation of China (No. 21472033)the National Key R&D Program of China (No. 2018YFB1501604)the Fundamental Research Funds for the Central Universities (No. PA2020GDKC0021)。
文摘The hydroarylation reaction of terminal alkynes with arylboronic acids catalyzed by low(400 ppm) loadings of palladium has been developed. The reaction is broad in scope and high-yielding, even on multigram scale. It is suitable for the synthesis of alkenes labeled with deuterium, and for the late-stage modification of bioactive molecules.
文摘Continuous measurement of blood pressure based on pulse transit time (PTT) using GMR sensors is the state-of-art non-invasive cuffless method in which modulated magnetic signature of blood (MMSB) is used. In this paper, the mechanism of MMSB is investigated. According to the experimental results, it is found that both blood pulse flowing through the applied magnetic field and the displacement of the GMR sensor caused by blood pulse contribute to the disturbance of magnetic field detected by GMR sensors. The feasibility of MMSB method is discussed as well.
文摘Continuous non-invasive blood pressure (BP) measurement can be realized by using pulse transit time (PTT) based on electrocardiogram (ECG) and pulse wave signal. Modulated magnetic signature of blood (MMSB) is a promising approach to obtain PTT. The origin of MMSB is critical to establish the relationship between MMSB and BP. In this paper, two possible origins of MMSB, blood disturbance mechanism and angular variation mechanism, are analyzed and verified through three control experi-ments under different conditions. The influence of blood velocity alteration and blood volume alteration on magnetic field is investigated though blood flow simulation sys-tem. It is found that MMSB comes mainly from the periodic blood flow while the per-turbation caused by angular variation between sensitive axis of the magnetic sensor and geomagnetic field can be neglected. As to blood disturbance mechanism, the change of blood volume plays a decisive role while the effect of blood velocity altera-tion is negligible.
基金funded by the National Natural Science Foundation of China(NSFC)under grant 62350710218.
文摘Piezoelectric MEMS loudspeakers based on cantilever diaphragms have demonstrated promising electroacoustic efficiency and low-frequency sound pressure level(SPL).However,their total harmonic distortion(THD)significantly increases near the first resonant frequency,and high-frequency SPL(above 10 kHz)rapidly decreases due to the resonance frequency and bandwidth limitations,severely affecting sound quality.This work presents a piezoelectric MEMS loudspeaker featuring a 2.7μm-thick sputtered PZT film,comprising a cantilever diaphragm and four sets of Double-S actuators.The first resonance frequency of the cantilever diaphragm is 3.2 kHz,and the Double-S actuators introduce an additional resonance frequency at 21.3 kHz,addressing the issues of insufficient high-frequency SPL and poor THD performance.Testing on a 711-ear simulator reveals that,under 1-3 Vpp excitation,incorporating the Double-S actuators leads to an average SPL increase of 23 dB and an average THD reduction of 80%that remains below 0.6% across the 3.2-20 kHz range.Thus,both SPL and THD performance in the mid-to high-frequency range are improved.This work paves the way for the development of high-fidelity piezoelectric MEMS loudspeakers,offering new opportunities to improve sound quality and extend the frequency range for in-ear applications.
文摘The attractive memristor is interpreted based on its constitutive relation.The memory property of the memristor is explained,along with the explanation on its three fingerprints：（1） Pinched hysteresis loop;（2） Hysteresis lobe area decreases as frequency increases;（3） Pinched hysteresis loop shrinks to a single-valued function at infinite frequency.Where the magnetic flux is in Strukov＇s memristor is also introduced.Resistive elements including the memristor are taken as an example to argue that the constitutive relation determines the electrical property of a circuit element and diagram method is used to distinguish different elements in the resistive element series.
文摘The concept of the memristor was proposed by Leon Chua in 1971, along with some electro-magnetic interpretations according to quasi-static expansion of Maxwell＇s equations. In 2003, Chua included the memristor into a four-element torus that has infinite circuit elements. This paper uses the quasi-static method to interpret every circuit element in the torus. Two examples are also provided to show how topologic structure of an element affects its electrical properties by affecting the dominant electro-magnetic field components. Additionally, it is proved that the circuit elements in the torus, except the resistive, capacitive and inductive elements, cannot exist independently. Moreover, the incorrectness in Chua＇s interpretation of the memristor, that the memristor cannot be interpreted with the transient quasi-static method due to its memory property, is pointed out. Finally, the limitations of the electro-magnetic interpretation method are discussed.
