Microwave Electric Field Research Articles

Sensitivity extension of atom-based amplitude-modulation microwave electrometry via high Rydberg states

The Rydberg atom-based microwave electric field sensor has high sensitivity for weak RF-field detection. Selection of Rydberg states with larger electric dipole moment is beneficial to enhance the sensitivity, and we choose Rydberg states with its principal quantum number up to n ∼ 80. We study the probe laser transmission response to a microwave field for these chosen high Rydberg states at room temperature. It agrees well with theoretical simulation based on an optical Bloch equation with considered microwave-atom interaction and Doppler broadening effect. In our experiment, the microwave sensing sensitivity based on 85 Rb transition | 78 S 1 / 2 ⟩ → | 78 P 3 / 2 ⟩ arrives at 5.102(49) nV cm − 1 Hz − 1 / 2 at 1 kHz.

Ferromagnetic resonance excited by interfacial microwave electric field: the role of current-induced torques

Excitation of magnetization dynamics in magnetic materials, especially in ultrathin ferromagnetic films, is of utmost importance for developing various ultrafast spintronics devices. Recently, the excitation of magnetization dynamics, i.e. ferromagnetic resonance (FMR) via electric field-induced modulation of interfacial magnetic anisotropies, has received particular attention due to several advantages, including lower power consumption. However, several additional torques generated by unavoidable microwave current induced because of the capacitive nature of the junctions may also contribute to the excitation of FMR apart from electric field-induced torques. Here, we study the FMR signals excited by applying microwave signal across the metal-oxide junction in CoFeB/MgO heterostructures with Pt and Ta buffer layers. Analysis of the resonance line shape and angular dependent behavior of resonance amplitude revealed that apart from voltage-controlled in-plane magnetic anisotropy (VC-IMA) torque a significant contribution can also arises from spin-torques and Oersted field torques originating from the flow of microwave current through metal-oxide junction. Surprisingly, the overall contribution from spin-torques and Oersted field torques are comparable to the VC-IMA torque contribution, even for a device with negligible defects. This study will be beneficial for designing future electric field-controlled spintronics devices.

A Microwave Field-Induced Nonlinear Metamaterial with Wafer Integration Level.

Field-induced nonlinear materials, with extended abilities of manipulating electromagnetic waves, have been widely employed in electromagnetic protection, absorption, and detection. Until now, it was found that the field-induced nonlinearity mainly shows in the optical and terahertz frequency bands. Applying the microwave band into such technical activities is hampered due to a lack of investigations on the nonlinearity caused by microwave electric fields, especially in the ultrawideband and microwave high-frequency bands. In this paper, a nonlinear metamaterial (NLMM) concept based on the integration of metamaterial structures and a semiconductor on the same wafer is proposed, which shows nonlinear behavior to the electromagnetics' field energy in the microwave band. The designed NLMM is transparent to low-density electromagnetic radiation fields, while it adaptively becomes opaque to high-density electromagnetic radiation fields. Two types of NLMM are designed to verify the nonlinear characteristics of ultrawide and narrow bands in the microwave band, respectively. The concept of NLMM can be used for the application of the microwave frequency band in electromagnetic protection and detection.

Precise measurement of microwave polarization using a Rydberg atom-based mixer.

A Rydberg atom-based mixer has opened up a new method to characterize microwave electric fields such as the precise measurement of their phase and strength. This study further demonstrates, theoretically and experimentally, a method to accurately measure the polarization of a microwave electric field based on a Rydberg atom-based mixer. The results show that the amplitude of the beat note changes with the polarization of the microwave electric field in a period of 180 degrees, and in the linear region a polarization resolution better than 0.5 degree can be easily obtained which reaches the best level by a Rydberg atomic sensor. More interestingly, the mixer-based measurements are immune to the polarization of the light field that forms the Rydberg EIT. This method considerably simplifies theoretical analysis and the experimental system required for measuring microwave polarization using Rydberg atoms and is of interest in microwave sensing.

Unusual heating effect of the elliptically polarized microwave electric field on sodium chloride solution: A molecular dynamics simulation

Our molecular dynamics simulation results show that the elliptically polarized microwave electric field would increase the heating efficiency of sodium chloride solution. The growth rate of the heating efficiency is positively correlated with the concentration of the sodium chloride solution and intensity of applied electric field. The rotation autocorrelation function results confirm that water molecules would do a more frequent rotational motion with the multidirectional polarization of elliptically polarized microwave electric field. The result of the more frequent rotational motion is consistent with that of the higher microwave energy absorption of energy analysis. The following analysis of hydrogen bond shows that the existence of ionic solutes would break the hydrogen bonds between water molecules and make it easier for water molecules to rotate with the applied electric field. These results indicate that elliptically polarized microwave electric field can indeed improve the heating efficiency of salt solution.

Microwave-assisted co-gasification of mixed plastics and corn stover: A synergistic approach to produce clean hydrogen

Co-gasification of waste plastic and corn stover into hydrogen is an effective way of reducing hydrogen cost and carbon footprint. However, current gasification technologies are energy intensive and cannot accommodate flexible feedstock. Microwave gasification offers several advantages including higher H2 yield and enhanced selectivity to syngas over tars. This work presents parametric optimization study of microwave co-gasification of mixed plastics and corn stover for hydrogen-rich syngas. High hydrogen yields of 30.5 mmolH2/gfeed at 700 °C were obtained using a microwave reactor, as opposed to 0.9 mmolH2/gfeed at 700–950 °C with conventional heating. Hydrogen yields are >98% of the theoretical extractable hydrogen from feedstock. Microwaves enhanced plastic and corn stover synergy and reduced tar yields. H-poor carbon formation resulting from the dehydrogenation of tar and coke, and light olefins decomposition, triggered by the external microwave electric fields, allowed further cracking of intermediate hydrocarbons to produce additional H2.

Comparison between Magnetic Fields and Electric Fields of Microwave Radiation for Heating the Solder Used to Connect a Transistor to a Printed Circuit Board

We demonstrated soldering of an electrical component (the metal-oxide semiconductor field effect transistor (MOSFET)) on a printed circuit bord (PCB) via solder paste heated by microwave irradiation. The behavior of the object soldered with solder heated in a microwave magnetic field and electric field were evaluated by using various microwave resonators. In the magnetic field, the solder paste was selectively heated by microwave irradiation. We confirmed that the MOSFET was connected onto the PCB without any damage and that the MOSFET operated normally. However, in an electric field, the solder paste cannot be heated by microwave irradiation because the edges of the PCB were selectively heated. Consequently, the MOSFET could not be connected onto the PCB. The strengths of the electromagnetic fields produced by different microwave resonators were numerically simulated to determine the optimal positions for microwave soldering. Based on the simulation results, microwave heating with separate magnetic and electric fields was carried out and we investigated the heating characteristics of the samples. The appearance and cross sections of the samples were observed by using scanning electron microscopy and energy dispersive X-ray spectroscopy. To estimate any damage by microwave irradiation of the MOSFET, we evaluated the output and transfer characteristics of the MOSFET. We conclude that microwave heating in a magnetic field was superior to heating with an electric field.

Decoupling thermal effects and possible non-thermal effects of microwaves in vacuum evaporation of glucose solutions

Microwave vacuum evaporation (MVE) is a promising alternative to conventional methods. However, the mechanisms underlying its efficiency remain elusive. In this study, the effects of microwaves on glucose solutions were investigated via molecular dynamics (MD) simulations and experimental studies to elucidate possible microwave non-thermal and thermal effects, respectively. MD simulations on energy-related parameters, interfacial properties, and molecular migration indicated that a microwave electric field of 10 5 V/m could not influence water evaporation behavior at a constant temperature of 90 °C, validating the absence of non-thermal effects in the MVE of glucose solutions. Meanwhile, superheating was not observed in this study during microwave heating at atmospheric pressure or in vacuum. High-intensity microwaves enabled the solution to reach its boiling point rapidly and remarkably induced an intensified film boiling during MVE, thereby shortening the evaporation time. Therefore, the high efficiency of MVE may be attributed to the thermal effects of strong microwaves. • Thermal effects and possible non-thermal effects during MVE were studied. • Non-thermal effects were not observed during microwave evaporation at 10 5 V/m. • 10 9 V/m-z and 10 9 V/m-x microwaves accelerated and impeded evaporation, respectively. • Superheating did not occur during microwave heating with solution agitation.

Numerical Optimal Configuration of Microwave Electric Field in Surfaguide Plasma Source for CO2 Conversion

Plasma technology in the conversion of CO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{2}$</tex-math> </inline-formula> and CH <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{4}$</tex-math> </inline-formula> to useful products shows great potential in clean energy sector. The nonthermal nature of plasma helps in enhancing selective chemical reactions, leading to the activation of the otherwise stable molecules, like CO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{2}$</tex-math> </inline-formula> . However, there exists a compromise between the energy efficiency and gas conversion efficiency. In order to improve energy as well as the gas conversion efficiency of the plasma source, various geometries of plasma source have been investigated. This study proposes a microwave (2.45 GHz) plasma source based on standard rectangular waveguide (WR340) with an introduction of reduced height waveguide (RHW) channel for CO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{2}$</tex-math> </inline-formula> gas conversion. The RHW transfers the microwave energy into a quartz tube, in which the plasma is subsequently produced. A comprehensive investigation of the microwave electric field profile within such configuration is carried out using COMSOL Multiphysics 5.6 software in view of the CO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{2}$</tex-math> </inline-formula> conversion. Based on the simulation results, two independent optimal designs are proposed for achieving an enhanced electric field at low-power microwaves. The first design incorporates a skewed plasma tube (SPT), in which the inner diameter of the quartz tube is kept constant while the outer diameter reduces linearly below the waveguide region. The second design introduces a thin metal rod (thickness 0.5 mm) in the tube (uniform thickness) from top surface. The results show that in the SPT configuration, the electric field is asymmetric along the plasma tube such that the field gets doubled ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim$</tex-math> </inline-formula> 5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{3}$</tex-math> </inline-formula> V/m at 100-W microwave power) in the upper half region of the tube. Such condition would be beneficial for establishing nonthermal equilibrium plasma. While enhanced power density will increase the energy efficiency, the nonequilibrium nature would lead to increase the conversion efficiency. For the second design, the position of the metal rod within the plasma can be adjusted to get the electric field as high as 1.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{4}$</tex-math> </inline-formula> V/m at 100-W microwave power, which is expected to achieve a maximum power transfer from microwave to plasma. The results are favorable for increasing the energy as well as the conversion efficiency of the microwave plasma source.

Competition between Direct Detection Mechanisms in Planar Bow-Tie Microwave Diodes on the Base of InAlAs/InGaAs/InAlAs Heterostructures.

The application of the unique properties of terahertz radiation is increasingly needed in sensors, especially in those operating at room temperature without an external bias voltage. Bow-tie microwave diodes on the base of InGaAs semiconductor structures meet these requirements. These diodes operate on the basis of free-carrier heating in microwave electric fields, which allows for the use of such sensors in millimeter- and submillimeter-wavelength ranges. However, there still exists some uncertainty concerning the origin of the voltage detected across these diodes. This work provides a more detailed analysis of the detection mechanisms in InAlAs/InGaAs selectively doped bow-tie-shaped semiconductor structures. The influence of the InAs inserts in the InGaAs layer is investigated under various illumination and temperature conditions. A study of the voltage-power characteristics, the voltage sensitivity dependence on frequency in the Ka range, temperature dependence of the detected voltage and its relaxation characteristics lead to the conclusion that a photo-gradient electromotive force arises in bow-tie diodes under simultaneous light illumination and microwave radiation.

Multidirectional Polarization Impacts on Microwave Heating Efficiency: A Molecular Dynamics Research of Microwave Heating of Common Solvents.

Energy efficiency has always been an inherent problem of microwave heating. In this work, the higher heating efficiency of the elliptically polarized microwave electric field is investigated via MD simulations, aiming to examine the multidirectional polarization effect during microwave heating. The MD results show that the heating efficiency growth rates of EtOH, AcOH, DMSO, H2O, and DMF are 3.17%, 3.92%, 4.14%, 5.00%, and 27.06% sequentially larger with the elliptically polarized microwave electric field (EF) than those with the linearly polarized microwave EF. Energy analyses indicate that the utilization rate of microwave energy would be increased of the elliptically polarized microwave EF with the same electric field intensities. The higher decay speed of the rotation autocorrelation function curves of elliptically polarized EF presents that the sample molecules do have a more frequent rotational motion to align with the varying polarization directions. Additionally, dielectric properties analysis gave the relation between the heating efficiency growth rate and the loss tangent of the samples. This microwave heating method is expected to be a new route to improve the microwave heating efficiency.

Improving the spectral resolution and measurement range of quantum microwave electrometry by cold Rydberg atoms

We theoretically and experimentally studied quantum microwave electrometry in a cold atomic system using Rydberg electromagnetic induction transparency (EIT) and Autler–Townes splitting (EIT-AT splitting). In cold atoms, a spectral linewidth of ∼500 kHz for EIT was achieved owing to a significant reduction in residual Doppler width, i.e. by at least an order of magnitude, compared to that in vapor cells at room temperature. Therefore, the minimum microwave electric field intensity (E MW) that can be measured is 430 µV cm−1, which is one order higher sensitivity in the EIT-AT regime than that in vapor cells at room temperature. Unlike microwave electrometry in atomic vapor cells, EIT-AT splitting cannot be observed if E MW is so large that the EIT-AT splitting interval exceeds the absorption peak width of the cold atom while scanning the frequency of the probe laser (ω p ). Moreover, EIT-AT splitting can be observed if exceeds the natural linewidth of the intermediate states while scanning the coupling laser (ω c ) and maintains a high spectral resolution with a high signal-to-noise ratio. While scanning ω c , the upper microwave electric field intensity is limited by the scanning range of our setup. Using our system, we measure the maximum field to be 21.6 mV cm−1, nearly three times higher than that of 6.8 mV cm−1 while scanning ω p . The results indicate that the linear range of E MW measured using EIT-AT splitting considerably improves in cold Rydberg atoms.

Effect of microwave electric field on asphaltene aggregation in a heavy oil system: MD and DFT investigation

An in-depth understanding of asphaltene aggregation is vital for the viscosity reduction of heavy oils, and essential for fully utilizing heavy oil resources. Therefore, the influence of microwave electric field on the aggregation of asphaltene in the heavy oil system was investigated via Molecular Dynamic simulation and Density Functional Theory calculation. The aggregation forms, interaction types and rheological behavior of asphaltene and other components were calculated by processing the trajectories. The results reveal that microwave electric fields play a significant role in the packing morphology of asphaltenes and other components at the micro-molecular level, leading to changes in the apparent viscosity of heavy oil system. It can be clearly manifested that under 5 V/nm of microwave electric field, asphaltenes primarily stack in π - π, connecting intimately with resin, constructing a stable colloidal structure of the system with high viscosity. Whereas, by enhancing the electric field, π-π stacking will gradually be destroyed, resulting in viscosity reduction. The T-shaped stacking of asphaltenes is favorable to form at 20 V/nm, inducing a stable network among the components, which is detrimental to the viscosity reduction. The achievements further confirm that an appropriate microwave electric field is the key to reducing the viscosity. In addition, considering the thermal and non-thermal effects of microwave, it is explored that microwave is more effective at low temperature. Therefore, the efficient combination of microwave power and treatment temperature is the critical factor to achieve better viscosity reduction effect.

Atom-based sensing technique of microwave electric and magnetic fields via a single rubidium vapor cell.

We present an atom-based approach for determining microwave electric and magnetic fields by using a single rubidium vapor cell in a microwave waveguide. For a 87Rb cascade three-level system employed in our experiment, a weak probe laser driving the lower transition, 5S1/2→5P3/2, is first used to measure the microwave magnetic field based on the atomic Rabi resonance. When a counter-propagating strong coupling laser is subsequently turned on to drive the Rydberg transition, 5P3/2→67D5/2, the same probe laser is then used as a Rydberg electromagnetically induced transparency (EIT) probe to measure the microwave electric field by investigating the resonant microwave dressed Autler-Townes splitting (ATS). By tuning the hyperfine transition frequency of the ground state using an experimentally feasible static magnetic field, we first achieved a measurement of the microwave electric and magnetic field strength at the same microwave frequency of 6.916 GHz. Based on the ideal relationship between the electric and magnetic field components, we obtained the equivalent microwave magnetic fields by fitting the inversion to the measured microwave electric fields, which demonstrated that the results were in agreement with the experimental measurement of the microwave magnetic fields in the same microwave power range. This study provides new experimental evidence for quantum-based microwave measurements of electric and magnetic fields by a single sensor in the same system.

Measurement of microwave electric field based on electromagnetically induced transparency by using cold Rydberg atoms

Microwave electric fields are measured by using cold Rydberg atoms. We obtain spindle-shaped cold atomic clouds in a magneto-optical trap and then pump the cold atoms to quantum state 5S&lt;sub&gt;1/2&lt;/sub&gt;, &lt;i&gt;F&lt;/i&gt; = 2, &lt;i&gt;m&lt;/i&gt;&lt;sub&gt;F&lt;/sub&gt; = 2 by using an optical-pump laser. We obtain the Rydberg electromagnetic induction transparency (EIT) spectrum peak with narrow linewidth by the low temperature and small residual Doppler broadening. The results show that the typical EIT linewidth with 16 μK cold atoms is about 460 kHz which is 15 times narrower than that of 7 MHz obtained in the thermal vapor cell. The microwave electric field amplitude is measured by Autler-Townes splitting (EIT-AT splitting) in the cold atoms at frequencies of 9.2, 14.2 and 22.1 GHz, receptively. The results show that there is a good linear relationship between the EIT-AT splitting interval and the microwave electric field amplitude. The lower limit of the microwave electric field amplitude that can be measured in the linear region can reach as low as 222 μV/cm, which is about 22 times larger than the lower limit in the traditional thermal vapor cell about of 5 mV/cm. The improvement of the lower limit by EIT-AT splitting method is roughly proportional to the narrowing EIT line width by cold atom samples. This demonstrates that benefiting from the smaller residual Doppler effect and the narrower EIT linewidth in cold atoms, the cold atom system is more advantageous in the experimental measuring of the weak microwave electric field amplitude by using the EIT-AT splitting method. This is of great benefit to the absolute calibration of very weak microwave electric fields. Furthermore, the lower limit of the microwave electric field amplitude that can be measured is smaller than 1 μV/cm by using the change of transmittance of the prober laser at the EIT resonance, and the corresponding sensitivity can reach 1 μV·cm&lt;sup&gt;–1&lt;/sup&gt;·Hz&lt;sup&gt;–1/2&lt;/sup&gt;. These results demonstrate the advantages of cold atomic sample in microwave electric field measurement and its absolute calibration.

Electromagnetic particle simulation of secondary electron multipactor characteristics in inner surface of 110 GHz microwave output window

The secondary electron multipactor on the inner surface of the output window is one of the main factors limiting the power capacity of high power microwave. Therefore, it is of great significance to carry out relevant research. In this work, the process of secondary electron multipactor and the resulting loss of power are numerically simulated by using the electromagnetic particle model with one-dimensional spatial distribution and three-dimensional velocity distribution at the microwave frequency of 110 GHz. The influences of microwave electric field at the surface and dielectric material type on the power loss are studied. The simulation results show that the electron number density is higher than the critical cut-off number density after the secondary electron multipactor has reached the steady state, but the microwave electric field does not show obvious change. This is because the electrons in a very high electrostatic field are mainly concentrated in the domain of several micrometers near the dielectric surface, which is far less than the corresponding skin depth. The electron number density in the multipactor steady state increases with the microwave electric field increasing, but the ratio of the power loss to the microwave power at the surface increases slowly. After the multipactor reaches the steady state, the number density of electrons near the sapphire surface is the highest, followed by the number density near the crystal quartz surface, and the number density near the fused quartz surface is the lowest, so the corresponding power loss decreases successively. In order to verify the accuracy of the model, the simulated value of the multipactor threshold is compared with the experimental data, and the difference between them is discussed.

Research on intrinsic expansion coefficients in Rydberg atomic heterodyne receiving link

Rydberg atom can respond to weak microwave electric field signal in real-time by using its electromagnetically induced transparency effect to realize down conversion of space microwave electric field signal, which can be used as a superheterodyne receiver. The Rydberg atom superheterodyne receiver is a new receiving system composed of Rydberg atoms, photodetectors, and electronic information processing modules. Presently, the physical response mechanism of Rydberg atomic superheterodyne receiving technology is studied in depth. However, no complete receiving link analysis model has been established, which is not conducive to optimizing its system performance. Based on the physical mechanism of the Rydberg atom responding to the microwave electric field, this paper introduces the concept of intrinsic expansion coefficient, establishes and experimentally verifies the receiving link model of the Rydberg atom superheterodyne receiver, and briefly discusses the influence of the intrinsic expansion coefficient on the system sensitivity and response characteristics, thereby providing the theoretical guidance for optimizing the performance of the Rydberg atom superheterodyne receiving system. In the end, the Rydberg atomic and the electronic receiving links' sensitivity performance is discussed and compared.

Numerical optimization of non-equilibrium plasma source for surface processing of materials

Over the years, non-equilibrium plasma sources have emerged as a promising technology in surface processing of materials. Various strategies have been employed to make significant advancement in the technology. However, the process optimization is found to depend on different factors like power supply frequency, gas species and gas pressure. In order to control material processing outcome, it is necessary to control plasma parameters as per requirement. In the present work, a surface microwave generated non-equilibrium plasma source is proposed for material processing applications. The source comprises of rectangular waveguide system and a quartz tube, whose dimensions are optimized based on the electric field profile obtained within the plasma tube in the presence of the microwave (f = 2.45 GHz). Argon gas is allowed to flow through the discharge tube at a velocity of 10 m/s keeping its pressure at 1 torr. The microwave electric field within the discharge tube ionizes the argon gas medium resulting into plasma state whose properties are investigated using commercially available COMSOL Multiphysics® software. The inner surface of the discharge tube is then filled with dielectric beads (radius = 2 mm) and the effect of the dielectric constant on the plasma properties are studied. An investigation of ion flux at different positions in the plasma tube suggests that in the absence of dielectric beads, remote contact mode of operation can be preferred while in the presence of dielectric beads, direct contact mode of operation can be implemented. These results are of significance for direct as well as remote mode of surface processing of materials.

Ultrasound-assisted green extraction methods: An approach for cosmeceutical compounds isolation from Macadamia integrifolia pericarp.

This study aimed was to examine the potential of several green extraction methods to extract cosmetic/cosmeceutical components from Macadamia integrifolia pericarps, which were a by-product of the macadamia nut industry. M. integrifolia pericarps were extracted by conventional solvent extraction process using 95% v/v ethanol and various green extraction methods, including infusion, ultrasound, micellar, microwave, and pulsed electric field extraction using water as a clean and green solvent. The extracts were evaluated for total phenolic content using Folin-Ciocalteu method.The antioxidant activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing/antioxidant power, and ferric-thiocyanate method. The anti-skin ageing activities were investigated by means of collagenase, elastase, and hyaluronidase inhibition using enzyme-substrate reaction assay. The irritation profile of the extracts was evaluated by the hen's egg test-chorioallantoic membrane (HET-CAM) test. The results noted that ultrasound-assisted extraction yielded the significantly highest extract amount with the significantly highest total phenolic content (p<0.05), especially when the extraction time was 10min. The aqueous extract from ultrasound-assisted extraction possessed the most potent antioxidant and anti-skin ageing activities (p<0.05). Its antioxidant activities were comparable to ascorbic acid and Trolox, whereas the anti-skin ageing activities were equivalent to epigallocatechin-3-gallate and oleanolic acid. Besides, the extract was safe since it induced no irritation in the HET-CAM test. Therefore, ultrasound-assisted extraction was suggested as an environmentally friendly extraction method for M. integrifolia pericarp extraction and further application in the cosmetic/cosmeceutical industries.

Microwave Electric Fields Measurement with One-dimensional Standing-wave Fields Based on Rydberg Atoms

Microwave Electric Fields Measurement with One-dimensional Standing-wave Fields Based on Rydberg Atoms