Microwave-induced thermoacoustic imaging(MTAI)has advantages including the large imaging depth,high imaging resolution,high imaging contrast,and fast imaging speed.The thermoacoustic(TA)group of South China Normal Uni...Microwave-induced thermoacoustic imaging(MTAI)has advantages including the large imaging depth,high imaging resolution,high imaging contrast,and fast imaging speed.The thermoacoustic(TA)group of South China Normal University has dedicated to developing TA imaging for more than a decade and has made many breakthroughs.This review introduces these breakthroughs from two aspects including the improvement in techniques and the exploration of applications.On the technological level,there are ultrashort microwave pulse(USMP)-inducedTA imaging that can improve the imaging resolution,nonlinear thermoacoustic imaging(NTAI)that can improve the imaging contrast,polarized microwave-inducedthermoacoustic imaging(P-MTAI)that can obtain cellular-level alignment information,and more convenient and accurate handheld and multimodal probes.On the application side,the optimization and expansion have been carried out,mainly concentrating on breast and myocardial imaging.Finally,several current research directions are introduced,including the application of P-MTAI on joint imaging and research on whole-body imaging of small animals.展开更多
The catalyst of CUOx/Al2O3 was prepared by the dipping-sedimentation method using y-Al2O3 as a supporter. CuO and Cu2O were loaded on the surface of Al2O3, characterized by X-ray diffraction （XRD） and X-ray photoele...The catalyst of CUOx/Al2O3 was prepared by the dipping-sedimentation method using y-Al2O3 as a supporter. CuO and Cu2O were loaded on the surface of Al2O3, characterized by X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. In the presence of CuOx/Al2O3, the microwave-induced chlorine dioxide （ClO2） catalytic oxidation process was conducted for the treatment of synthetic wastewater containing 100 mg/L phenol. The factors influencing phenol removal were investigated and the results showed that microwave-induced C102-CuOx/ml203 process could effectively degrade contaminants in a short reaction time with a low oxidant dosage, extensive pH range. Under a given condition （ClO2 concentration 80 mg/L, microwave power 50 W, contact time 5 latin, catalyst dosage 50 g/L, pH 9）, phenol removal percentage approached 92.24%, corresponding to 79.13% of CODcr removal. The removal of phenol by microwave-induced ClO2-CuOx/Al2O3 catalytic oxidation process was a complicated non-homogeneous solid/water reaction, which fitted pseudo-first-order by kinetics. Compared with traditional ClO2 oxidation, ClO2 catalytic oxidation and microwave-induced ClO2 oxidation, microwave-induced ClO2 catalytic oxidation system could significantly enhance the degradation efficiency. It provides an effective technology for the removal of phenol wastewater.展开更多
This study introduces a test system for microwave-induced fracturing of hard rocks under true triaxial stress.The test system comprises a true triaxial stress loading system,an open-ended microwaveinduced fracturing s...This study introduces a test system for microwave-induced fracturing of hard rocks under true triaxial stress.The test system comprises a true triaxial stress loading system,an open-ended microwaveinduced fracturing system,a data acquisition system,an acoustic emission(AE)monitoring system,and an auxiliary specimen loading system.Microwave-induced surface and borehole fracturing tests under true triaxial stress were fulfilled for the first time,which overcomes the problem of microwave leakage in the coupling loading of true triaxial stress and microwave.By developing the dynamic monitoring system,the thermal response and fracture evolution were obtained during microwave irradiation.The monitoring system includes the infrared thermometry technique for monitoring rock surface temperature,the distributed optic fiber sensing technique for monitoring temperature in borehole in rock,the AE technique and two-dimensional digital speckle correlation technique for monitoring the evolution of thermal damage and the rock fracturing process.To validate the advantages of the test system and investigate the characteristics of microwave-induced fracturing of hard rocks,the study demonstrates the experimental methods and results for microwave-induced surface and borehole fracturing under true triaxial stress.The results show that thermal cracking presented intermittent characteristics(calm eactiveecalm)during microwave-induced surface and borehole fracturing of basalt.In addition,true triaxial stress can inhibit the development and distribution of thermal cracks during microwave-induced surface fracturing.When microwave-induced borehole fracturing occurs,it promotes the distribution of thermal cracks in rock,but inhibits the width of cracks.The results also prove the reliability of the test system.展开更多
This paper is aimed to study the effect of ADL on expression of ~z-AR and Mz-AchR in myocardial cells of rats exposed to microwave radiation. Immunohistochemistry, Western blot and image analysis were used to detect t...This paper is aimed to study the effect of ADL on expression of ~z-AR and Mz-AchR in myocardial cells of rats exposed to microwave radiation. Immunohistochemistry, Western blot and image analysis were used to detect the expression of ~I-AR and Mz-AchR in myocardial cells at 7 and 14 d after microwave exposure. The results show that the expression level was higher in microwave exposure group and 0.75 g/（kg.d） ADL group than in sham operation group and significantly lower in 1.5 and 3.0 g/（kg.d） ADL groups than in microwave group. So we have a conclusion that the expression of I^z-AR and Mz-AchR is down-regulated in myocardial cells of rats exposed to microwave radiation. ADL can protect rats against microwave-induced heart tissue injury.展开更多
Perovskite LaMnO3 powders with an average crystallite size of 12.5 nm were rapidly synthesized via a microwave-induced autocombustion reaction using glycine as a fuel and nitrate as an oxidant. After self-propagating ...Perovskite LaMnO3 powders with an average crystallite size of 12.5 nm were rapidly synthesized via a microwave-induced autocombustion reaction using glycine as a fuel and nitrate as an oxidant. After self-propagating combustion, the desired nanocrystalline perovskite LaMnO3 was obtained and no further calcination was carried out. The possible processes of combustion reaction were discussed according to the principle of propellant chemistry. The autocombustion and thermal decomposition of the precursor were investigated using the TG-DTA and FT-IR techniques. The influences of glycine-nitrate molar ratio and heat-treatment temperature on the perovskite phase formation and crystallite size of as-burnt powder were studied by XRD. The morphology and size of the as-burnt powder before and after milling were characterized and compared by TEM.展开更多
Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spec...Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spectrum, transmission electron microscopy, and infrared spectrum. Its acid catalytic activity was evaluated in the esterification reaction of acetic acid and n-butyl alcohol. The results show that Ce0.5Zr0.5O2 solid solution has cubic fluorite structure, and its particle diameter is in the nanometer scale. As a sort of solid acid, it possesses a higher acid catalytic activity and can be easily separated from reaction liquids. It can be used for several times, and basically, its activity keeps constant. The proton acid sites and Lewis acid sites exist in the structure of Ce0.5Zr0.5O2 solid solution.展开更多
A microwave-induced thermoacoustic imaging(MITAT)system is a non-destructive physical medical imaging method that combines the advantages of the high contrast of microwave imaging and the high resolution of ultrasound...A microwave-induced thermoacoustic imaging(MITAT)system is a non-destructive physical medical imaging method that combines the advantages of the high contrast of microwave imaging and the high resolution of ultrasound imaging.It uses the microwave as the excitation source and ultrasound as the information carrier.When different kinds of biological tissue absorb electromagnetic energy,it results in localized temperature rises.The thermal expansion will induce ultrasonic signals(i.e.,thermoacoustic signals),known as the thermoacoustic effect.The microwave absorption image of the sample can be reconstructed by algorithm processing.The MITAT contrast depends on different dielectric parameters of different kinds of tissue.We introduce the developed system and its application.In addition,the challenges and prospects of MITAT for further development are discussed.展开更多
Microwave-induced thermo-acoustic tomography (MITAT) is a promising technique with great potential in biomedical imaging. It has both the high contrast of the microwave imaging and the high resolution of the ultrasoun...Microwave-induced thermo-acoustic tomography (MITAT) is a promising technique with great potential in biomedical imaging. It has both the high contrast of the microwave imaging and the high resolution of the ultrasound imaging. In this paper, the proportional relationship between the absorbed microwave energy distribution and the induced ultrasound source distribution is derived. Further, the time reversal mirror (TRM) technique based on the pseudo-spectral time domain (PSTD) method is applied to MITAT system. The simulation results show that high contrast and resolution can be achieved by the TRM technique based on PSTD method even for the received signals with very low signal-to-noise ratio (SNR) and the model parameter with random fluctuation.展开更多
Puncture biopsy is an important clinical technique to obtain diseased tissue for pathological diagnosis,where imaging guidance is critical.In this paper,we describe a metal reflector-enhanced microwave-induced thermoa...Puncture biopsy is an important clinical technique to obtain diseased tissue for pathological diagnosis,where imaging guidance is critical.In this paper,we describe a metal reflector-enhanced microwave-induced thermoacoustic imaging(TAI)approach capable of guiding puncture biopsy for detection of breast cancer and joint diseases.Numerical experimentations simulating puncture guidance in breast cancer and knee gout models werefirst conducted using(CST STUDIO SUITE)(CST)software,and then ex-vivo experiments were performed followed by qualitative observations and semi-quantitative analysis.The results of both the simulations and ex-vivo experiments showed that our reflector-enhanced TAI could image the puncture needle in high resolution with a large depth of>12 cm.展开更多
Microwave-induced metal discharge(MMD)technology offers a novel methodology for efficient gas-phase catalytic reaction due to its unique heating effect,plasma effect and discharge effect.Herein,we successfully used a ...Microwave-induced metal discharge(MMD)technology offers a novel methodology for efficient gas-phase catalytic reaction due to its unique heating effect,plasma effect and discharge effect.Herein,we successfully used a special kind of uniformly distributed particles with synergistic microwave-induced fluidized-metal discharge(MFD)effect.A lab-scale atmospheric quartz tube fluidized bed reactor was designed.Apparatus like highspeed camera,fiber spectrometer and infrared thermometer were used to record the discharge phenomena.The effects of operating conditions such as gas velocity,microwave power,carrier gas type,and metal type on the discharge behavior were investigated in detail.Subsequently,the MFD was applied into the methane dry reform reaction(MDR)with excellent conversion compared with the conventional heating conditions.Gratifyingly,the metal particles can both be the converter of microwave and the catalyst of the reaction.The reported conclusion provides a novel way to intensification the reaction process and utilize microwave energy.展开更多
We describe the design and the use of a circular poly(methyl methacrylate)(PMMA)crystallization platform capable of processing 21 samples in Metal-Assisted and Microwave-Accelerated Evaporative Crystallization(MA-MAEC...We describe the design and the use of a circular poly(methyl methacrylate)(PMMA)crystallization platform capable of processing 21 samples in Metal-Assisted and Microwave-Accelerated Evaporative Crystallization(MA-MAEC).The PMMA platforms were modified with silver nanoparticle films(SNFs)to generate a microwave-induced temperature gradient between the solvent and the SNFs due to the marked differences in their physical properties.Since amino acids only chemisorb on to silver on the PMMA platform,SNFs served as selective and heterogeneous nucleation sites for amino acids.Theoretical simulations for electric field and temperature distributions inside a microwave cavity equipped with a PMMA platform were carried out to determine the optimum experimental conditions,i.e.,temperature variations and placement of the PMMA platform inside a microwave cavity.In addition,the actual temperature profiles of the amino acid solutions were monitored for the duration of the crystallization experiments carried out at room temperature and during microwave heating.The crystallization of five amino acids(L-threonine,L-histidine,L-leucine,L-serine and L-valine-HCl)at room temperature(control experiment)and using MA-MAEC were followed by optical microscopy.The induction time and crystal growth rates for all amino acids were determined.Using MA-MAEC,for all amino acids the induction times were significantly reduced(up to~8-fold)and the crystal growth rates were increased(up to~50-fold)as compared to room temperature crystallization,respectively.All crystals were characterized by Raman spectroscopy and powder x-ray diffraction,which demonstrated that the crystal structures of all amino acids grown at room temperature and using MA-MAEC were similar.展开更多
We demonstrate the design and the proof-of-concept use of a new,circular poly(methyl methacrylate)-based bioassay platform(PMMA platform),which affords for the rapid processing of 16 samples at once.The circular PMMA ...We demonstrate the design and the proof-of-concept use of a new,circular poly(methyl methacrylate)-based bioassay platform(PMMA platform),which affords for the rapid processing of 16 samples at once.The circular PMMA platform(5 cm in diameter)was coated with a silver nanoparticle film to accelerate the bioassay steps by microwave heating.A model colorimetric bioassay for biotinylated albumin(using streptavidin-labeled horse radish peroxidase)was performed on the PMMA platform coated with and without silver nanoparticles(a control experiment),and at room temperature and using microwave heating.It was shown that the simulated temperature profile of the PMMA platform during microwave heating were comparable to the real-time temperature profile during actual microwave heating of the constructed PMMA platform in a commercial microwave oven.The model colorimetric bioassay for biotinylated albumin was successfully completed in~2 min(total assay time)using microwave heating,as compared to 90 min at room temperature(total assay time),which indicates a~45-fold decrease in assay time.Our PMMA platform design afforded for significant reduction in non-specific interactions and low background signal as compared to non-silvered PMMA surfaces when employed in a microwave-accelerated bioassay carried out in a conventional microwave cavity.展开更多
In this study,we demonstrated a unique application of our Metal-Assisted and Microwave-Accelerated Evaporative Crystallization(MA-MAEC)technique for the de-crystallization of uric acid crystals,which causes gout in hu...In this study,we demonstrated a unique application of our Metal-Assisted and Microwave-Accelerated Evaporative Crystallization(MA-MAEC)technique for the de-crystallization of uric acid crystals,which causes gout in humans when monosodium urate crystals accumulate in the synovial fluid found in the joints of bones.Given the shortcomings of the existing treatments for gout,we investigated whether the MA-MAEC technique can offer an alternative solution to the treatment of gout.Our technique is based on the use of metal nanoparticles(i.e.,gold colloids)with low microwave heating to accelerate the de-crystallization process.In this regard,we employed a two-step process;(i)crystallization of uric acid on glass slides,which act as a solid platform to mimic a bone,(ii)de-crystallization of uric acid crystals on glass slides with the addition of gold colloids and low power microwave heating,which act as“nano-bullets”when microwave heated in a solution.We observed that the size and number of the uric acid crystals were reduced by>60%within 10 minutes of low power microwave heating.In addition,the use of gold colloids without microwave heating(i.e.control experiment)did not result in the de-crystallization of the uric acid crystals,which proves the utility of our MA-MAEC technique in the de-crystallization of uric acid.展开更多
We present a platform technology, called Metal-Assisted and Microwave-Accelerated Decrystallization (MAMAD), which is based on the use of dispersion of gold colloids with low power microwave heating to decrystallize o...We present a platform technology, called Metal-Assisted and Microwave-Accelerated Decrystallization (MAMAD), which is based on the use of dispersion of gold colloids with low power microwave heating to decrystallize organic and biological crystals attached to surfaces. Uric acid crystals were chosen as model target crystals to be decrystallized using MAMAD technique. A two-step procedure was employed: 1) growth of uric acid crystals on a model surface (collagen films coated on to glass slides to simulate a human joint) at room temperature and 2) de-crystallization of uric acid crystals in synovial fluid (in vitro) using silver and gold colloids in conjunction with low power microwave heating. Using the MAMAD technique with gold colloids, the number of uric acid crystals was drastically reduced by 80% after 10 min, where the average size of the uric acid crystals was reduced from 125 μm to 50 μm. In control experiments and with silver colloids that aggregated from the solution, the size and number of uric crystals remained unchanged, indicating that the combined use of only metal colloids in solution and microwave heating is effective for the de-crystallization of uric acid crystals in biological media.展开更多
文摘Microwave-induced thermoacoustic imaging(MTAI)has advantages including the large imaging depth,high imaging resolution,high imaging contrast,and fast imaging speed.The thermoacoustic(TA)group of South China Normal University has dedicated to developing TA imaging for more than a decade and has made many breakthroughs.This review introduces these breakthroughs from two aspects including the improvement in techniques and the exploration of applications.On the technological level,there are ultrashort microwave pulse(USMP)-inducedTA imaging that can improve the imaging resolution,nonlinear thermoacoustic imaging(NTAI)that can improve the imaging contrast,polarized microwave-inducedthermoacoustic imaging(P-MTAI)that can obtain cellular-level alignment information,and more convenient and accurate handheld and multimodal probes.On the application side,the optimization and expansion have been carried out,mainly concentrating on breast and myocardial imaging.Finally,several current research directions are introduced,including the application of P-MTAI on joint imaging and research on whole-body imaging of small animals.
基金Project supported by the National Nature Science Foundation of China(No.50678045).
文摘The catalyst of CUOx/Al2O3 was prepared by the dipping-sedimentation method using y-Al2O3 as a supporter. CuO and Cu2O were loaded on the surface of Al2O3, characterized by X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. In the presence of CuOx/Al2O3, the microwave-induced chlorine dioxide （ClO2） catalytic oxidation process was conducted for the treatment of synthetic wastewater containing 100 mg/L phenol. The factors influencing phenol removal were investigated and the results showed that microwave-induced C102-CuOx/ml203 process could effectively degrade contaminants in a short reaction time with a low oxidant dosage, extensive pH range. Under a given condition （ClO2 concentration 80 mg/L, microwave power 50 W, contact time 5 latin, catalyst dosage 50 g/L, pH 9）, phenol removal percentage approached 92.24%, corresponding to 79.13% of CODcr removal. The removal of phenol by microwave-induced ClO2-CuOx/Al2O3 catalytic oxidation process was a complicated non-homogeneous solid/water reaction, which fitted pseudo-first-order by kinetics. Compared with traditional ClO2 oxidation, ClO2 catalytic oxidation and microwave-induced ClO2 oxidation, microwave-induced ClO2 catalytic oxidation system could significantly enhance the degradation efficiency. It provides an effective technology for the removal of phenol wastewater.
基金the National Natural Science Foundation of China(Grant No.41827806)and the Liaoning Revitalization Talent Program(Grant No.XLYC1801002).
文摘This study introduces a test system for microwave-induced fracturing of hard rocks under true triaxial stress.The test system comprises a true triaxial stress loading system,an open-ended microwaveinduced fracturing system,a data acquisition system,an acoustic emission(AE)monitoring system,and an auxiliary specimen loading system.Microwave-induced surface and borehole fracturing tests under true triaxial stress were fulfilled for the first time,which overcomes the problem of microwave leakage in the coupling loading of true triaxial stress and microwave.By developing the dynamic monitoring system,the thermal response and fracture evolution were obtained during microwave irradiation.The monitoring system includes the infrared thermometry technique for monitoring rock surface temperature,the distributed optic fiber sensing technique for monitoring temperature in borehole in rock,the AE technique and two-dimensional digital speckle correlation technique for monitoring the evolution of thermal damage and the rock fracturing process.To validate the advantages of the test system and investigate the characteristics of microwave-induced fracturing of hard rocks,the study demonstrates the experimental methods and results for microwave-induced surface and borehole fracturing under true triaxial stress.The results show that thermal cracking presented intermittent characteristics(calm eactiveecalm)during microwave-induced surface and borehole fracturing of basalt.In addition,true triaxial stress can inhibit the development and distribution of thermal cracks during microwave-induced surface fracturing.When microwave-induced borehole fracturing occurs,it promotes the distribution of thermal cracks in rock,but inhibits the width of cracks.The results also prove the reliability of the test system.
文摘This paper is aimed to study the effect of ADL on expression of ~z-AR and Mz-AchR in myocardial cells of rats exposed to microwave radiation. Immunohistochemistry, Western blot and image analysis were used to detect the expression of ~I-AR and Mz-AchR in myocardial cells at 7 and 14 d after microwave exposure. The results show that the expression level was higher in microwave exposure group and 0.75 g/（kg.d） ADL group than in sham operation group and significantly lower in 1.5 and 3.0 g/（kg.d） ADL groups than in microwave group. So we have a conclusion that the expression of I^z-AR and Mz-AchR is down-regulated in myocardial cells of rats exposed to microwave radiation. ADL can protect rats against microwave-induced heart tissue injury.
基金Project supported bythe National Natural Science Foundation of China (50306008) and the Fund fromthe Preli minary Research Project of General Equipment Ministry (41328030507)
文摘Perovskite LaMnO3 powders with an average crystallite size of 12.5 nm were rapidly synthesized via a microwave-induced autocombustion reaction using glycine as a fuel and nitrate as an oxidant. After self-propagating combustion, the desired nanocrystalline perovskite LaMnO3 was obtained and no further calcination was carried out. The possible processes of combustion reaction were discussed according to the principle of propellant chemistry. The autocombustion and thermal decomposition of the precursor were investigated using the TG-DTA and FT-IR techniques. The influences of glycine-nitrate molar ratio and heat-treatment temperature on the perovskite phase formation and crystallite size of as-burnt powder were studied by XRD. The morphology and size of the as-burnt powder before and after milling were characterized and compared by TEM.
基金This work was financially supported by the Teaching Reform Study Program of Ludong University (No.Y0715).
文摘Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spectrum, transmission electron microscopy, and infrared spectrum. Its acid catalytic activity was evaluated in the esterification reaction of acetic acid and n-butyl alcohol. The results show that Ce0.5Zr0.5O2 solid solution has cubic fluorite structure, and its particle diameter is in the nanometer scale. As a sort of solid acid, it possesses a higher acid catalytic activity and can be easily separated from reaction liquids. It can be used for several times, and basically, its activity keeps constant. The proton acid sites and Lewis acid sites exist in the structure of Ce0.5Zr0.5O2 solid solution.
基金the National Natural Science Foundation of China under Grant No.12304533Start-up Foundation for Ph.D.of Southwest University of Science and Technology under Grant No.20zx7120.
文摘A microwave-induced thermoacoustic imaging(MITAT)system is a non-destructive physical medical imaging method that combines the advantages of the high contrast of microwave imaging and the high resolution of ultrasound imaging.It uses the microwave as the excitation source and ultrasound as the information carrier.When different kinds of biological tissue absorb electromagnetic energy,it results in localized temperature rises.The thermal expansion will induce ultrasonic signals(i.e.,thermoacoustic signals),known as the thermoacoustic effect.The microwave absorption image of the sample can be reconstructed by algorithm processing.The MITAT contrast depends on different dielectric parameters of different kinds of tissue.We introduce the developed system and its application.In addition,the challenges and prospects of MITAT for further development are discussed.
基金Supported by the National Natural Science Foundation of China(Grant No.60771042)the National Hi-Tech Research and Development Program("863"Project)(Grant No.2007AA12Z159)+2 种基金111Project(Grant No.B07046)SiChuan Excellent Youth Foun-dation(Grant No.08ZQ026-039)Program for New Century Excellent Talents in University of China and Program for Changjiang Scholars
文摘Microwave-induced thermo-acoustic tomography (MITAT) is a promising technique with great potential in biomedical imaging. It has both the high contrast of the microwave imaging and the high resolution of the ultrasound imaging. In this paper, the proportional relationship between the absorbed microwave energy distribution and the induced ultrasound source distribution is derived. Further, the time reversal mirror (TRM) technique based on the pseudo-spectral time domain (PSTD) method is applied to MITAT system. The simulation results show that high contrast and resolution can be achieved by the TRM technique based on PSTD method even for the received signals with very low signal-to-noise ratio (SNR) and the model parameter with random fluctuation.
基金supported in part by the Chinese Postdoctoral Science Foundation(2022MD723722)in part by the National Natural Science Foundation of China(62001075)in part by the Chongqing postdoctoral research project(special funding project 2021XM2026).
文摘Puncture biopsy is an important clinical technique to obtain diseased tissue for pathological diagnosis,where imaging guidance is critical.In this paper,we describe a metal reflector-enhanced microwave-induced thermoacoustic imaging(TAI)approach capable of guiding puncture biopsy for detection of breast cancer and joint diseases.Numerical experimentations simulating puncture guidance in breast cancer and knee gout models werefirst conducted using(CST STUDIO SUITE)(CST)software,and then ex-vivo experiments were performed followed by qualitative observations and semi-quantitative analysis.The results of both the simulations and ex-vivo experiments showed that our reflector-enhanced TAI could image the puncture needle in high resolution with a large depth of>12 cm.
基金The authors are grateful for financial support from the National Natural Science Foundation of China(21878219)the National Key R&D Program of China(2018YFB0604900).
文摘Microwave-induced metal discharge(MMD)technology offers a novel methodology for efficient gas-phase catalytic reaction due to its unique heating effect,plasma effect and discharge effect.Herein,we successfully used a special kind of uniformly distributed particles with synergistic microwave-induced fluidized-metal discharge(MFD)effect.A lab-scale atmospheric quartz tube fluidized bed reactor was designed.Apparatus like highspeed camera,fiber spectrometer and infrared thermometer were used to record the discharge phenomena.The effects of operating conditions such as gas velocity,microwave power,carrier gas type,and metal type on the discharge behavior were investigated in detail.Subsequently,the MFD was applied into the methane dry reform reaction(MDR)with excellent conversion compared with the conventional heating conditions.Gratifyingly,the metal particles can both be the converter of microwave and the catalyst of the reaction.The reported conclusion provides a novel way to intensification the reaction process and utilize microwave energy.
基金supported by Maryland Innovation Initiative(Phase 1)Award from Technology Development Corporation(TEDCO)support was provided by Award Number 5-K25EB007565-05 from the National Institute of Biomedical Imaging and Bioengineering.
文摘We describe the design and the use of a circular poly(methyl methacrylate)(PMMA)crystallization platform capable of processing 21 samples in Metal-Assisted and Microwave-Accelerated Evaporative Crystallization(MA-MAEC).The PMMA platforms were modified with silver nanoparticle films(SNFs)to generate a microwave-induced temperature gradient between the solvent and the SNFs due to the marked differences in their physical properties.Since amino acids only chemisorb on to silver on the PMMA platform,SNFs served as selective and heterogeneous nucleation sites for amino acids.Theoretical simulations for electric field and temperature distributions inside a microwave cavity equipped with a PMMA platform were carried out to determine the optimum experimental conditions,i.e.,temperature variations and placement of the PMMA platform inside a microwave cavity.In addition,the actual temperature profiles of the amino acid solutions were monitored for the duration of the crystallization experiments carried out at room temperature and during microwave heating.The crystallization of five amino acids(L-threonine,L-histidine,L-leucine,L-serine and L-valine-HCl)at room temperature(control experiment)and using MA-MAEC were followed by optical microscopy.The induction time and crystal growth rates for all amino acids were determined.Using MA-MAEC,for all amino acids the induction times were significantly reduced(up to~8-fold)and the crystal growth rates were increased(up to~50-fold)as compared to room temperature crystallization,respectively.All crystals were characterized by Raman spectroscopy and powder x-ray diffraction,which demonstrated that the crystal structures of all amino acids grown at room temperature and using MA-MAEC were similar.
基金supported by Award Number 5-K25EB007565-05 from the National Institute of Biomedical Imaging and Bioengineering.
文摘We demonstrate the design and the proof-of-concept use of a new,circular poly(methyl methacrylate)-based bioassay platform(PMMA platform),which affords for the rapid processing of 16 samples at once.The circular PMMA platform(5 cm in diameter)was coated with a silver nanoparticle film to accelerate the bioassay steps by microwave heating.A model colorimetric bioassay for biotinylated albumin(using streptavidin-labeled horse radish peroxidase)was performed on the PMMA platform coated with and without silver nanoparticles(a control experiment),and at room temperature and using microwave heating.It was shown that the simulated temperature profile of the PMMA platform during microwave heating were comparable to the real-time temperature profile during actual microwave heating of the constructed PMMA platform in a commercial microwave oven.The model colorimetric bioassay for biotinylated albumin was successfully completed in~2 min(total assay time)using microwave heating,as compared to 90 min at room temperature(total assay time),which indicates a~45-fold decrease in assay time.Our PMMA platform design afforded for significant reduction in non-specific interactions and low background signal as compared to non-silvered PMMA surfaces when employed in a microwave-accelerated bioassay carried out in a conventional microwave cavity.
基金supported(to B.Kioko)by National Institutes of Health(MBRS RISE)award number 5-R25GM058904-14.
文摘In this study,we demonstrated a unique application of our Metal-Assisted and Microwave-Accelerated Evaporative Crystallization(MA-MAEC)technique for the de-crystallization of uric acid crystals,which causes gout in humans when monosodium urate crystals accumulate in the synovial fluid found in the joints of bones.Given the shortcomings of the existing treatments for gout,we investigated whether the MA-MAEC technique can offer an alternative solution to the treatment of gout.Our technique is based on the use of metal nanoparticles(i.e.,gold colloids)with low microwave heating to accelerate the de-crystallization process.In this regard,we employed a two-step process;(i)crystallization of uric acid on glass slides,which act as a solid platform to mimic a bone,(ii)de-crystallization of uric acid crystals on glass slides with the addition of gold colloids and low power microwave heating,which act as“nano-bullets”when microwave heated in a solution.We observed that the size and number of the uric acid crystals were reduced by>60%within 10 minutes of low power microwave heating.In addition,the use of gold colloids without microwave heating(i.e.control experiment)did not result in the de-crystallization of the uric acid crystals,which proves the utility of our MA-MAEC technique in the de-crystallization of uric acid.
文摘We present a platform technology, called Metal-Assisted and Microwave-Accelerated Decrystallization (MAMAD), which is based on the use of dispersion of gold colloids with low power microwave heating to decrystallize organic and biological crystals attached to surfaces. Uric acid crystals were chosen as model target crystals to be decrystallized using MAMAD technique. A two-step procedure was employed: 1) growth of uric acid crystals on a model surface (collagen films coated on to glass slides to simulate a human joint) at room temperature and 2) de-crystallization of uric acid crystals in synovial fluid (in vitro) using silver and gold colloids in conjunction with low power microwave heating. Using the MAMAD technique with gold colloids, the number of uric acid crystals was drastically reduced by 80% after 10 min, where the average size of the uric acid crystals was reduced from 125 μm to 50 μm. In control experiments and with silver colloids that aggregated from the solution, the size and number of uric crystals remained unchanged, indicating that the combined use of only metal colloids in solution and microwave heating is effective for the de-crystallization of uric acid crystals in biological media.
