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Sample records for microwave heating obtencao

  1. Variable frequency microwave heating apparatus

    DOEpatents

    Bible, Don W.; Lauf, Robert J.; Johnson, Arvid C.; Thigpen, Larry T.

    1999-01-01

    A variable frequency microwave heating apparatus (10) designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity (34) for testing or other selected applications. The variable frequency microwave heating apparatus (10) includes a microwave signal generator (12) and a high-power microwave amplifier (20) or a high-power microwave oscillator (14). A power supply (22) is provided for operation of the high-power microwave oscillator (14) or microwave amplifier (20). A directional coupler (24) is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity (34). A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

  2. Microwave heating apparatus and method

    DOEpatents

    Johnson, Andrew J.; Petersen, Robert D.; Swanson, Stephen D.

    1990-01-01

    An apparatus is provided for heating and melting materials using microwave energy, and for permitting them to solidify. The apparatus includes a microwave energy source, a resonant cavity having an opening in its floor, a microwave energy choke encompassing the opening in the floor of the cavity, a metal container to hold the materials to be heated and melted, a turntable, and a lift-table. During operation, the combined action of the turntable and the lift-table position the metal container so that the top of the container is level with the floor of the cavity, is in substantial registration with the floor opening, and is encompassed by the microwave energy choke; thus, during operation, the interior of the container defines part of the resonant cavity. Additionally, a screw feeder, extending into the cavity and sheltered from microwave energy by a conveyor choke, may convey the materials to be heated to the container. Also, preferably, the floor of the resonant cavity may include perforatins, so that the offgases and dust generated in the apparatus may be removed from the resonant cavity by pulling outside air between the container choke and the exterior wall of the container into the resonant cavity and out from the cavity through the perforations.

  3. Microwave heat treating of manufactured components

    DOEpatents

    Ripley, Edward B.

    2007-01-09

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases. The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  4. Modeling of microwave heating of particulate metals

    NASA Astrophysics Data System (ADS)

    Mishra, P.; Upadhyaya, A.; Sethi, G.

    2006-10-01

    Recent studies have shown that metal powder compacts can be heated to high temperatures using microwaves. While microwave heating of ceramics is well understood and modeled, there is still uncertainty about the exact mechanism and mode of microwave heating of particulate metals. The current study describes an approach for modeling the microwave heating of metal powder compacts using an electromagnetic-thermal model. The model predicts the variation in temperature with time during sintering. The effect of powder size, emissivity, and susceptor heating on the heating rate has also been assessed. These predictions have been validated by the experimental observations of the thermal profiles of Sn-, Cu-, and W-alloy compacts, using a 2.45 GHz multimode microwave furnace.

  5. Controlled Microwave Heating Accelerates Rolling Circle Amplification

    PubMed Central

    Yoshimura, Takeo; Suzuki, Takamasa; Mineki, Shigeru; Ohuchi, Shokichi

    2015-01-01

    Rolling circle amplification (RCA) generates single-stranded DNAs or RNA, and the diverse applications of this isothermal technique range from the sensitive detection of nucleic acids to analysis of single nucleotide polymorphisms. Microwave chemistry is widely applied to increase reaction rate as well as product yield and purity. The objectives of the present research were to apply microwave heating to RCA and indicate factors that contribute to the microwave selective heating effect. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. Here, we showed that microwave-assisted RCA reactions catalyzed by either of the four thermostable DNA polymerases were accelerated over 4-folds compared with conventional RCA. Furthermore, the temperatures of the individual buffer components were specifically influenced by microwave heating. We concluded that microwave heating accelerated isothermal RCA of DNA because of the differential heating mechanisms of microwaves on the temperatures of reaction components, although the overall reaction temperatures were the same. PMID:26348227

  6. Microwave heating of ceramic composites

    NASA Astrophysics Data System (ADS)

    Pelesko, J. A.; Kriegsmann, G. A.

    2000-02-01

    The microwave heating of a ceramic composite is modelled and analysed. The composite consists of many small ceramic particles embedded in a ceramic cement. The composite is assumed to be well insulated, and each particle is assumed to be in imperfect thermal contact with the surrounding cement. Based on these two assumptions an asymptotic theory exploiting the small Biot number and small non-dimensional contact conductance is developed. Our asymptotic theory yields a set of nonlinear partial differential equations which govern the temperature in the composite. These are reduced to a set of coupled nonlinear ordinary differential equations in which the surface area of each particle enters as a parameter. Recent experiments with such composites have shown that the steady-state temperature of the composite is strongly dependent upon the radii of the embedded particles. Our model captures this effect. In fact, our analysis shows that the assumption of imperfect thermal contact between the particles and the ceramic cement is essential for this trend to be established.

  7. Using Microwaves to Heat Lunar Soil

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.

    2011-01-01

    This slide presentation reviews the use of microwaves to heat lunar soil in order to obtain water. There appears to be large amounts of water in the lunar poles, in Martian areas in lower latitudes and some of the Moons of Jupiter. The presence of water in the south lunar polar region was demonstrated by the Lunar CRater Observation and Sensing Satellite (LCROSS) mission. Microwaves can be used to extract water from lunar soil without excavation. Using microwaves on a lunar soil simulant at least 95% of the water from the regolith permafrost simulant was extracted (2 minutes). The process is modeled using COMSOL Multiphysics Finite Element analysis microwave physics module and demonstrated usingan experiment of an microwave apparatus on a rover.

  8. Selection of biological indicator for validating microwave heating sterilization.

    PubMed

    Sasaki, K; Mori, Y; Honda, W; Miyake, Y

    1998-01-01

    For the purpose of selecting an appropriate biological indicator for evaluation of the effects of microwave heating sterilization, we examined aerobic bacterial spores to determine whether microwaves have non-thermal sterilization effects. After microwave irradiation on dry bacterial spores (three species), none of the bacterial spores were killed. The survival rate of the spores after microwave irradiation of spore suspensions (twelve species) was compared with that after heating by a conventional method. The order of heat resistance in the bacterial species was similar between the two heating methods. Bacillus stearothermophilus spores were the most heat-resistant. These results suggest that microwaves have no non-thermal sterilization effects on bacterial spores, the specific resistant spores to microwave heating, and microwave heating sterilization can be evaluated in the same way as for conventional heating sterilization. As a biological indicator for evaluation of overkill sterilization, B. stearothermophilus spores may be appropriate for microwave heating sterilization as well as steam sterilization. PMID:9610169

  9. Hybrid Microwave-Cavity Heat Engine

    NASA Astrophysics Data System (ADS)

    Bergenfeldt, Christian; Samuelsson, Peter; Sothmann, Björn; Flindt, Christian; Büttiker, Markus

    2014-02-01

    We propose and analyze the use of hybrid microwave cavities as quantum heat engines. A possible realization consists of two macroscopically separated quantum-dot conductors coupled capacitively to the fundamental mode of a microwave cavity. We demonstrate that an electrical current can be induced in one conductor through cavity-mediated processes by heating up the other conductor. The heat engine can reach Carnot efficiency with optimal conversion of heat to work. When the system delivers the maximum power, the efficiency can be a large fraction of the Carnot efficiency. The heat engine functions even with moderate electronic relaxation and dephasing in the quantum dots. We provide detailed estimates for the electrical current and output power using realistic parameters.

  10. Glycerol citrate polyesters produced through microwave heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of various heating methods without catalysis to prepare copolyesters from citric acid:glycerol blends were studied. In the presence of short term microwave treatments, i.e., 60 sec at 1200 W, blends of glycerol and citric acid invariably formed solid amorphous copolyesters. Fourier tra...

  11. Apparatus for microwave heat treatment of manufactured components

    DOEpatents

    Ripley, Edward B.

    2008-04-15

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases. The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  12. Methods for microwave heat treatment of manufactured components

    DOEpatents

    Ripley, Edward B.

    2010-08-03

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases. The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  13. Microwave heating of lunar materials. Appendix A

    NASA Technical Reports Server (NTRS)

    Meek, Thomas T.

    1992-01-01

    Microwave heating of nonmetallic inorganic material has been of interest for many years. Von Hippel in the late 1940's and early 1950's investigated how microwave radiation up to 10 GHz couples to various insulator materials. Perhaps the most work has been done by Wayne Tinga at the University of Edmonton. Most of the work to date has been done at the two frequency bands allowed in industrial use (0.915 GHz and 2.45 GHz). However some work has recently been carried out at 28 GHz and 60 GHz. Work done in this area at Los Alamos National Laboratory is discussed.

  14. Effect of Microwave Heating on Phytosterol Oxidation.

    PubMed

    Leal-Castañeda, Everth Jimena; Inchingolo, Raffaella; Cardenia, Vladimiro; Hernandez-Becerra, Josafat Alberto; Romani, Santina; Rodriguez-Estrada, María Teresa; Galindo, Hugo Sergio García

    2015-06-10

    The oxidative stability of phytosterols during microwave heating was evaluated. Two different model systems (a solid film made with a phytosterol mixture (PSF) and a liquid mixture of phytosterols and triolein (1:100, PS + TAG (triacylglycerol))) were heated for 1.5, 3, 6, 12, 20, and 30 min at 1000 W. PS degraded faster when they were microwaved alone than in the presence of TAG, following a first-order kinetic model. Up to 6 min, no phytosterol oxidation products (POPs) were generated in both systems. At 12 min of heating, the POP content reached a higher level in PSF (90.96 μg/mg of phytosterols) than in PS + TAG (22.66 μg/mg of phytosterols), but after 30 min of treatment, the opposite trend was observed. 7-Keto derivates were the most abundant POPs in both systems. The extent of phytosterol degradation depends on both the heating time and the surrounding medium, which can impact the quality and safety of the food product destined to microwave heating/cooking. PMID:25973984

  15. Graphene oxide reduction by microwave heating

    NASA Astrophysics Data System (ADS)

    Longo, Angela; Carotenuto, Gianfranco

    2016-05-01

    The possibility to prepare thermal reduced graphene oxide (Tr-GO) colloidal suspensions by microwave heating of graphene oxide (GO) suspensions in N-methyl-2-pyrrolidone (NMP) has been investigated. According to transmission electron microscopy (TEM) and absorption and emission spectroscopy characterization, such a type of thermal reduction does not lead to graphene quantum dots formation because only mono-functional oxygen-containing groups are removed.

  16. Numerical modeling of waveguide heated microwave plasmas

    SciTech Connect

    Venkateswaran, S.; Schwer, D.A.; Merkle, C.L.

    1993-12-01

    Waveguide-heated microwave plasmas for space propulsion applications are analyzed by a two-dimensional numerical solution of the combined Navier-Stokes and Maxwell equations. Two waveguide configurations -- one purely transmitting and the other with a reflecting end wall -- are considered. Plasma stability and absorption characteristics are studied and contrasted with the characteristic of resonant cavity heated plasmas. In addition, preliminary estimates of the overall efficiency and the thrust and specific impulse of the propulsion system are also made. The computational results are used to explain experimental trends and to better understand the working of these devices.

  17. A container for heat treating materials in microwave ovens

    DOEpatents

    Holcombe, C.E.; Dykes, N.L.; Kimrey, H.D. Jr.; Mills, J.E.

    1988-01-26

    The efficiency of a microwave oven of a conventional two-source configuration and energy level is increased by providing the oven with a container for housing a refractory material to be treated. The container is formed to top and bottom walls transparent to microwaves while the sidewalls, in a circular configuration, are formed of a nonmetallic material opaque to microwave radiation for reflecting the radiation penetrating the top and bottom walls radially inwardly into the center of the container wherein a casket of heat-insulating material is provided for housing the material to be heat treated. The reflection of the microwave radiation from the sidewalls increases the concentration of the microwaves upon the material being heat treated while the concentration of the microwaves upon the material being heat treated while the casket retains the heat to permit the heating of the material to a substantially higher temperature than achievable in the oven without the container.

  18. Microwave heating and current drive in tokamaks

    SciTech Connect

    Cohen, B.I.; Cohen, R.H.; Kerbel, G.D.; Logan, B.G.; Matsuda, Y.; McCoy, M.G.; Nevins, W.M.; Rognlien, T.D.; Smith, G.R.; Harvey, R.W.; Kritz, A.H.; Bonoli, P.T.; Porkolab, M.

    1988-08-23

    The use of powerful microwave sources provide unique opportunities for novel and efficient heating and current-drive schemes in the electron-cyclotron and lower-hybrid ranges of frequencies. Free- electron lasers and relativistic klystrons are new sources that have a number of technical advantages over conventional, lower-intensity sources; their use can lead to improved current-drive efficiencies and better penetration into a reactor-grade plasma in specific cases. This paper reports on modeling of absorption and current drive, in intense-pulse and quasilinear regimes, and on analysis of parametric instabilities and self-focusing. 16 refs., 2 figs.

  19. A New Automated Microwave Heating Process for Cooking and Pasteurization of Microwaveable Foods Containing Raw Meats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new microwave heating process was developed for cooking microwaveable foods containing raw meats. A commercially available inverter-based microwave oven was modified for pasteurization of mechanically tenderized beef, inoculated with Escherichia coli O157:H7 (~ 5 log cfu/g) and packaged in a 12 o...

  20. Microwave Tokamak Experiment (MTX) ohmic heating system

    SciTech Connect

    Jackson, M.C. )

    1989-09-13

    The ohmic heating system for the Microwave Tokamak Experiment (MTX) at Lawrence Livermore National Laboratory (LLNL) provides both the voltage for the initial breakdown phase and the energy to drive the plasma current to a value of 400 kA or greater. Providing this voltage and flux swing requires a one-turn loop voltage of about 25 volts (11 kV across the coil) and a magnetic flux swing of 2 volt- seconds. This voltage and flux swing are accomplished by charging the ohmic heating coils to 20 kA, at which point the current is commutated off into a resistor generating the 11 kV across the coil. When the current passes through zero, another power supply drives the current in the opposite polarity to 20 kA, thus completing the full 2 volt-second flux swing. This paper describes the design features and performance of the ohmic heating circuit, with emphasis on the commutation circuit. In addition, the paper describes the use of the ohmic heating system for discharge cleaning and the changeover procedure. 3 refs., 4 figs., 1 tab.

  1. Container for heat treating materials in microwave ovens

    DOEpatents

    Holcombe, Cressie E.; Dykes, Norman L.; Kimrey, Jr., Harold D.; Mills, James E.

    1989-01-01

    The efficiency of a microwave oven of a conventional two-source configuration and energy level is increased by providing the oven with a container for housing a refractory material to be treated. The container is formed of top and bottom walls transparent to microwaves while the sidewalls, in a circular configuration, are formed of a nonmetallic material opaque to microwave radiation reflecting the radiation penetrating the top and bottom walls radially inwardly into the center of the container wherein a casket of heat-insulating material is provided for housing the material to be heat treated. The reflection of the microwave radiation from the sidewalls increases the concentration of the microwaves upon the material being heat treated while the casket retains the heat to permit the heating of the material to a substantially higher temperature than achieveable in the oven without the container.

  2. Polymeric flocculants processing by accelerated electron beams and microwave heating

    NASA Astrophysics Data System (ADS)

    Martin, Diana I.; Mateescu, Elena; Craciun, Gabriela; Ighigeanu, Daniel; Ighigeanu, Adelina

    2002-08-01

    Results obtained by accelerated electron beam, microwave and simultaneous microwave and electron beam application in the chemistry of acrylamide and acrylic acid copolymers (polymeric flocculants used for wastewater treatment) are presented. Comparative results concerning the molecular weight and Huggins' constant for the acrylamide and acrylic acid copolymers obtained by classical heating, microwave heating, electron beam irradiation and simultaneous microwave and electron beam treatment are reported. Microwave heating produces high water solubility of the polymeric flocculants but median molecular weight values. Electron beam irradiation gives high molecular weight values but associated with a cross-linked structure (poor water solubility) while microwave energy addition to electron beam energy gives simultaneously high molecular weight values and high water solubility.

  3. Compact Directional Microwave Antenna for Localized Heating

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W.; Lin, Gregory Y.; Chu, Andrew W.; Dobbins, Justin A.; Arndt, G. Dickey; Ngo, Phong

    2008-01-01

    A directional, catheter-sized cylindrical antenna has been developed for localized delivery of microwave radiation for heating (and thus killing) diseased tissue without excessively heating nearby healthy tissue. By "localized" is meant that the antenna radiates much more in a selected azimuthal direction than in the opposite radial direction, so that it heats tissue much more on one side than it does on the opposite side. This antenna can be inserted using either a catheter or a syringe. A 2.4-mm prototype was tested, although smaller antennas are possible. Prior compact, cylindrical antennas designed for therapeutic localized hyperthermia do not exhibit such directionality; that is, they radiate in approximately axisymmetric patterns. Prior directional antennas designed for the same purpose have been, variously, (1) too large to fit within catheters or (2) too large, after deployment from catheters, to fit within the confines of most human organs. In contrast, the present antenna offers a high degree of directionality and is compact enough to be useable as a catheter in some applications.

  4. Dynamic measurement of starch granule swelling during microwave heating.

    PubMed

    Casasnovas, Johnny; Anantheswaran, Ramaswamy C

    2016-10-20

    The size of starch granules in dilute aqueous suspension was measured in-line during gelatinization in a microwave-heated, well-mixed system. The results were compared with those of a previous study conducted with conventional heating. For the starches used (common corn, waxy maize, and cross-linked waxy maize), no significant difference was found between microwave and conventional heating in terms of maximum diameter, temperature of maximum rate of diameter increase, or diameter vs. temperature behavior. These results suggest that there are no differences in the swelling behavior of common and modified maize starches between microwave and conventional heating. PMID:27474654

  5. Finite element computer model of microwave heated ceramics

    SciTech Connect

    Liqiu Zhou; Gang Liu; Jian Zhou

    1995-12-31

    In this paper, a 3-D finite element model to simulate the heating pattern during microwave sintering of ceramics in a TE{sub 10}{sup n} single mode rectangular cavity is described. A series of transient temperature profiles and heating rates of the ceramic cylinder and cubic sample were calculated versus different parameters such as thermal conductivity, dielectric loss factor, microwave power level, and microwave energy distribution. These numerical solutions may provide a better understanding of thermal runaway and solutions to microwave sintering of ceramics.

  6. The scientific base of heating water by microwave

    NASA Astrophysics Data System (ADS)

    Akdoǧan, Ender; ćiftçi, Muharrem

    2016-03-01

    This article is based on the master thesis [4] related to our invention which was published in World Intellectual Property Organization (WO/2011/048506) as a microwave water heater. In the project, a prototype was produced to use microwave in industrial heating. In order to produce the prototype, the most appropriate material kind for microwave-water experiments was determined by a new energy loss rate calculation technique. This new energy loss calculation is a determinative factor for material permeability at microwave frequency band (1-100 GHz). This experimental series aim to investigate the rationality of using microwave in heating industry. Theoretically, heating water by microwave (with steady frequency 2.45 GHz) is analyzed from sub-molecular to Classical Mechanic results of heating. In the study, we examined Quantum Mechanical base of heating water by microwave experiments. As a result, we derived a Semi-Quantum Mechanical equation for microwave-water interactions and thus, Wien displacement law can be derived to verify experimental observations by this equation.

  7. Microwave heating for the rapid generation of glycosylhydrazides.

    PubMed

    Mallevre, F; Roget, A; Minon, T; Kervella, Y; Ropartz, D; Ralet, M C; Canut, H; Livache, T

    2013-07-17

    Conditions for simple derivatization of reducing carbohydrates via adipic acid dihydrazide microwave-assisted condensation are described. We demonstrate with a diverse set of oligo- and polysaccharides how to improve a restrictive and labor intensive conventional conjugation protocol by using microwave-assisted chemistry. We show that 5 min of microwave heating in basic or acidic conditions are adequate to generate, in increased yields, intact and functional glycosylhydrazides, whereas hours to days and acidic conditions are generally required under conventional methods. PMID:23731134

  8. Multiphysics modeling of microwave heating of whole tomato

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A mathematical model of a food is useful for prediction of temperature profiles during microwave heating. However, due to their complex geometry and interaction with electromagnetic fields, whole tomatoes resist an analytical approach to modeling the fruit as it is subjected to microwave energy. T...

  9. Synthesis and Modification of Carbon Nanomaterials utilizing Microwave Heating.

    PubMed

    Schwenke, Almut M; Hoeppener, Stephanie; Schubert, Ulrich S

    2015-07-22

    Microwave-assisted synthesis and processing represents a growing field in materials research and successfully entered the field of carbon nanomaterials during the last decade. Due to the strong interaction of carbon materials with microwave radiation, fast heating rates and localized heating can be achieved. These features enable the acceleration of reaction processes, as well as the formation of nanostructures with special morphologies. A comprehensive overview is provided here on the possibilities and achievements in the field of carbon-nanomaterial research when using microwave-based heating approaches. This includes the synthesis and processing of carbon nanotubes and fibers, graphene materials, carbon nanoparticles, and capsules, as well as porous carbon materials. Additionally, the principles of microwave-heating, in particular of carbon materials, are introduced and important issues, i.e., safety and reproducibility, are discussed. PMID:26087742

  10. Flow-Dependent Vascular Heat Transfer during Microwave Thermal Ablation

    PubMed Central

    Chiang, Jason; Hynes, Kieran; Brace, Christopher L.

    2012-01-01

    Microwave tumor ablation is an attractive option for thermal ablation because of its inherent benefits over radiofrequency ablation (RFA) in the treatment of solid tumors such as hepatocellular carcinoma (HCC). Microwave energy heats tissue to higher temperatures and at a faster rate than RFA, creating larger, more homogenous ablation zones. In this study, we investigate microwave heating near large vasculature using coupled fluid-flow and thermal analysis. Low-flow conditions are predicted to be more likely to cause cytotoxic heating and, therefore, vessel thrombosis and endothelial damage of downstream tissues. Such conditions may be more prevalent in patient with severe cirrhosis or compromised blood flow. High-flow conditions create the more familiar heat-sink effect that can protect perivascular tissues from the intended thermal damage. These results may help guide placement and use of microwave ablation technologies in future studies. PMID:23367194

  11. A Study on Uniform Heating of Solid Foods and High Viscosity Foods by Microwave Heating

    NASA Astrophysics Data System (ADS)

    Suga, Ryosuke; Hashimoto, Osamu; Ijuin, Taichi; Takatomi, Tetsuya

    In this paper, an microwave oven for disinfectant one application has been modeled by FDTD-HTE Method and reserched uniform heating of solution model simulated solid food and high viscosity food. We suggest two technique for uniform heating. First one is that water film is arranged around the food for reducing local heating of edge heating. Second one is that food is heated by using both steam and microwave. As a result, 2mm water film lower temperature of high temperature part in the food efficiently, by using uniform heating technique using water film. And we confirmed that 33% of uneven heating is improved. Moreover, we confirmed that steam heated edge of food and microwave heated center of food, and food is gone to about 60 degrees centigrade through uniform technique using both Steam and microwave.

  12. Numerical Analysis of Heat Transfer Characteristics in Microwave Heating of Magnetic Dielectrics

    NASA Astrophysics Data System (ADS)

    Peng, Zhiwei; Hwang, Jiann-Yang; Park, Chong-Lyuck; Kim, Byoung-Gon; Onyedika, Gerald

    2012-03-01

    A numerical simulation of heat transfer during the microwave heating process of magnetite, which is a two-dimensional (2-D) magnetic dielectric, subjected to heat conduction, convection, and radiation was performed. The heat transfer process was modeled using an explicit finite-difference approach, and the temperature profiles for different heating parameters were generated through developing a code in Mathematica 7.0 (Wolfram Research, Inc., Champaign, IL). The temperature in the sample increases rapidly in 1 minute and nonuniform temperature distribution inside the object is observed. An obvious temperature hot spot is formed in the corner of the predicted temperature profile initially, which shifts to the center of the object as heating power increases. Microwave heating at 915 MHz exhibits better heating uniformity than 2450 MHz mainly because of the larger microwave penetration depth. It is also observed that the heating homogeneity in the object can be improved by reducing the dimension of object. The effects of heating time, microwave power, microwave frequency, and object dimension need to be considered to obtain high heating performance and avoid/minimize thermal runaway resulting from temperature nonuniformity in large-scale microwave heating.

  13. Zirconium diboride nanofiber generation via microwave arc heating

    NASA Astrophysics Data System (ADS)

    Baldridge, Tyson; Gupta, Mool C.

    2008-07-01

    Ultrahigh temperature zirconium diboride nanofibers were produced by microwave arc heating using micron-sized raw powder. While microwave heating the ZrB2 powder, the development of local arcing led to rapid heating and solidification of the samples, along with the creation of nanofibers. The morphology of these high aspect ratio nanofibers was characterized using scanning electron microscopy and transmission electron microscopy. Energy dispersive x-ray spectroscopy, electron energy loss spectroscopy and selected area electron diffraction showed the composition to contain zirconium, boron, nitrogen, aluminum and oxygen as well as the crystallographic orientation. ZrB2 nanofiber applications include aerospace and other harsh environments.

  14. Investigating the trade-offs of microwave susceptors in energetic composites: Microwave heating versus combustion performance

    NASA Astrophysics Data System (ADS)

    Crane, C. A.; Pantoya, M. L.; Weeks, B. L.

    2014-03-01

    Recently, microwave technology has been used to ignite energetic materials when studies showed that metal powders readily absorb microwave energy. This study investigates adding a graphite susceptor to an energetic composite consisting of aluminum (Al) and iron (III) oxide (Fe2O3) and examines microwave coupling to the sample. In a companion study, the combustion of this thermite as a function of susceptor concentration was also studied to evaluate the trade-off between enhancing microwave coupling and flame propagation speed. Results show that graphite enhances microwave coupling up to 10% by mass concentration but reduces heating at higher percentages that exceed a percolation threshold. As susceptor concentrations increased greater than one mass percent, the flame propagation speed correspondingly decreased.

  15. Transient temperature distributions in a cylinder heated by microwaves

    SciTech Connect

    Jackson, H.W.; Barmatz, M.; Wagner, P.

    1996-12-31

    Transient temperature distributions were calculated for a lossy dielectric cylinder coaxially aligned in a cylindrical microwave cavity excited in a single mode. Results were obtained for sample sizes that range from fibers to large cylinders. Realistic values for temperature dependent complex dielectric constants and thermophysical properties of the samples were used. Losses in cavity walls were taken into account as were realistic thermal emissivities at all surfaces. For a fine mesh of points in time, normal mode properties and microwave power absorption profiles were evaluated using analytic expressions. Those expressions correspond to exact solutions of Maxwell`s equations within the framework of a cylindrical shell model. Heating produced by the microwave absorption was included in self-consistent numerical solutions of thermal equations. In this model, both direct microwave heating and radiant heating of the sample (hybrid heating) were studied by including a lossy dielectric tube surrounding the sample. Calculated results are discussed within the context of two parametric studies. One is concerned with relative merits of microwave and hybrid heating of fibers, rods, and larger cylinders. The other is concerned with thermal runaway.

  16. Synthesis of ultrafine powders by microwave heating

    DOEpatents

    Meek, Thomas T.; Sheinberg, Haskell; Blake, Rodger D.

    1988-01-01

    A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has been removed. The resulting material is an ultrafine powder. This method can be used to make Al.sub.2 O.sub.3, NiO+Al.sub.2 O.sub.3 and NiO as well as a number of other materials including GaBa.sub.2 Cu.sub.3 O.sub.x.

  17. Synthesis of ultrafine powders by microwave heating

    DOEpatents

    Meek, T.T.; Sheinberg, H.; Blake, R.D.

    1987-04-24

    A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has dissolved. The resulting material is an ultrafine powder. This method can be used to make Al/sub 2/O/sub 3/, NiO /plus/ Al/sub 2/O/sub 3/ and NiO as well as a number of other materials including GaBa/sub 2/Cu/sub 3/O/sub x/. 1 tab.

  18. Analysis of a microwave-heated planar propagating hydrogen plasma

    SciTech Connect

    Knecht, J.P.; Micci, M.M.

    1988-02-01

    The heating of a gas to high temperatures by absorption of microwave radiation has been proposed as a potential electrothermal rocket propulsion system. One possible mode of microwave energy absorption is by means of a planar plasma region propagating toward the source of the microwave radiation. Such a planar propagating plasma can be spatially stabilized by a gas stream flowing in the same direction as the microwave radiation with a velocity equal to the plasma propagation velocity. A one-dimensional analysis of the microwave-heated planar propagating plasma for hydrogen gas was developed to predict maximum gas temperatures and propagation velocities. The governing electromagnetic and energy equations were numerically integrated with temperature-dependent thermodynamic properties of equilibrium hydrogen. The propagation velocity eigenvalue was solved by means of an iterative technique. Temperature distribution in the gas, propagation velocities, and percent power absorbed, reflected and transmitted, were obtained as a function of incident microwave power at a frequency of 2.45 GHza for hydrogen gas pressures of 1 and 10 atm. 19 references.

  19. Heating of tissues by microwaves: a model analysis.

    PubMed

    Foster, K R; Lozano-Nieto, A; Riu, P J; Ely, T S

    1998-01-01

    We consider the thermal response times for heating of tissue subject to nonionizing (microwave or infrared) radiation. The analysis is based on a dimensionless form of the bioheat equation. The thermal response is governed by two time constants: one (tau1) pertains to heat convection by blood flow, and is of the order of 20-30 min for physiologically normal perfusion rates; the second (tau2) characterizes heat conduction and varies as the square of a distance that characterizes the spatial extent of the heating. Two idealized cases are examined. The first is a tissue block with an insulated surface, subject to irradiation with an exponentially decreasing specific absorption rate, which models a large surface area of tissue exposed to microwaves. The second is a hemispherical region of tissue exposed at a spatially uniform specific absorption rate, which models localized exposure. In both cases, the steady-state temperature increase can be written as the product of the incident power density and an effective time constant tau(eff), which is defined for each geometry as an appropriate function of tau1 and tau2. In appropriate limits of the ratio of these time constants, the local temperature rise is dominated by conductive or convective heat transport. Predictions of the block model agree well with recent data for the thresholds for perception of warmth or pain from exposure to microwave energy. Using these concepts, we developed a thermal averaging time that might be used in standards for human exposure to microwave radiation, to limit the temperature rise in tissue from radiation by pulsed sources. We compare the ANSI exposure standards for microwaves and infrared laser radiation with respect to the maximal increase in tissue temperature that would be allowed at the maximal permissible exposures. A historical appendix presents the origin of the 6-min averaging time used in the microwave standard. PMID:9771585

  20. Microwave dielectric heating of drops in microfluidic devices.

    PubMed

    Issadore, David; Humphry, Katherine J; Brown, Keith A; Sandberg, Lori; Weitz, David A; Westervelt, Robert M

    2009-06-21

    We present a technique to locally and rapidly heat water drops in microfluidic devices with microwave dielectric heating. Water absorbs microwave power more efficiently than polymers, glass, and oils due to its permanent molecular dipole moment that has large dielectric loss at GHz frequencies. The relevant heat capacity of the system is a single thermally isolated picolitre-scale drop of water, enabling very fast thermal cycling. We demonstrate microwave dielectric heating in a microfluidic device that integrates a flow-focusing drop maker, drop splitters, and metal electrodes to locally deliver microwave power from an inexpensive, commercially available 3.0 GHz source and amplifier. The temperature change of the drops is measured by observing the temperature dependent fluorescence intensity of cadmium selenide nanocrystals suspended in the water drops. We demonstrate characteristic heating times as short as 15 ms to steady-state temperature changes as large as 30 degrees C above the base temperature of the microfluidic device. Many common biological and chemical applications require rapid and local control of temperature and can benefit from this new technique. PMID:19495453

  1. Sintering of zirconia ceramics using microwave and spark heating techniques

    NASA Astrophysics Data System (ADS)

    Ivashutenko, A. S.; Frangulyan, T. S.; Ghyngazov, S. A.; Petrova, A. B.

    2016-02-01

    The paper presents the results of an complex study of structural and mechanical properties of zirconia ceramics sintered using different techniques. The samples were sintered via the conventional method of heating, in the field of microwave radiation and spark plasma. The experimental data indicates that a microwave field and spark plasma have a stimulating effect on zirconia ceramics sintering. In contrast to the microwave sintering, spark plasma sintering provides ceramics with improved properties at similar time-temperature annealing modes. Moreover, the properties of the ceramics under spark plasma sintering at T=1300 °C are similar to the properties of the ceramics sintered in a microwave field at T=1400 °C.

  2. Microwave heating effect on rheology and microstructure of white sauces.

    PubMed

    Guardeño, Luis M; Sanz, Teresa; Fiszman, Susana M; Quiles, Amparo; Hernando, Isabel

    2011-10-01

    The microstructure and rheological properties of white sauces formulated with different starches were analyzed after being microwave-heated for different times. Significant differences (P < 0.05) in rheological parameters analyzed-storage modulus (G'), loss modulus (G″), and loss tangent (tanδ)-were obtained for sauces made with different starches. Microwave reheating did not affect G' and G″ values until water evaporation became significant. In addition, tanδ values did not change significantly (P < 0.05) even during long reheating times showing that sauce viscoelastic properties did not change after microwave irradiation. However, microstructure assessed by confocal laser scanning microscopy showed changes in fat globule and protein. These microstructural changes did not seem to have a significant effect on rheological measurements since starch and ι-carrageenan are mainly responsible for the viscoelastic behavior of the sauces. Practical Application:  The development of products appropriate to microwave heating is constantly rising in food industry. It is necessary to understand the behavior of the ingredients and the final product to microwave heating in order to choose those ingredients which will develop the best performance. Starches are common ingredients in industrial sauces, and rheological and microstructural techniques have shown their usefulness in characterization of starch-based systems. PMID:21913921

  3. Microwave dielectric heating of fluids in an integrated microfluidic device

    NASA Astrophysics Data System (ADS)

    Shah, Jayna J.; Sundaresan, Siddarth G.; Geist, Jon; Reyes, Darwin R.; Booth, James C.; Rao, Mulpuri V.; Gaitan, Michael

    2007-11-01

    The ability to selectively and precisely control the temperature of fluid volumes ranging from a few microliters to sub-nanoliters in microfluidic networks is vital for a wide range of applications in micro total analysis systems (μTAS). In this work, we characterize and model the performance of a thin film microwave transmission line integrated with a microfluidic channel to heat fluids with relevant buffer salt concentrations over a wide range of frequencies. A microchannel fabricated in poly(dimethylsiloxane) (PDMS) is aligned with a thin film microwave transmission line in a coplanar waveguide (CPW) configuration. The electromagnetic fields localized in the gap between the signal and ground lines of the transmission line dielectrically heat the fluid in the selected region of the microchannel. Microwave S-parameter measurements and optical fluorescence-based temperature measurements are used with a theoretical model developed based on classical microwave absorption theory to fully characterize the temperature rise of the fluid. We observe a 0.95 °C mW-1 temperature rise at 15 GHz and confirm that the temperature rise of the fluid is predominantly due to microwave dielectric heating.

  4. Spatial observation and quantification of microwave heating in materials

    NASA Astrophysics Data System (ADS)

    Crane, C. A.; Pantoya, M. L.; Weeks, B. L.

    2013-08-01

    An electromagnetic exposure chamber was designed to safely deliver electromagnetic power in the range of microwaves between 0.8 and 4.2 GHz to a thin cylindrical materials. This instrumentation is unique because the diagnostics not only measure sample heating with a response time of 1.3 ms, but also energy transmitted and reflected. Energy absorption at different frequencies was quantified via electromagnetic heating using an infrared camera. This in situ IR imaging of the spatial distribution of temperature during microwave exposure coupled with sensors for determining transmitted and reflected energy enables novel new microwave energy experiments. Samples were exposed to a portion of both the electric and magnetic fields inside a waveguide and based on sample dimensions, the field strengths were assumed uniform across the sample. Three materials were examined: two were borosilicate, first coated with graphite paint and a second without the coating; and, the third was a compressed sample of flake graphite pressed to 69% of its bulk density. Results are in agreement with the theories of microwave heating and verify the functionality of this experimental design. This diagnostic will be important in future tests where a variety of different materials can be exposed to weak electromagnetic waves and their efficiency in coupling to the microwaves can be examined.

  5. Consolidation of lunar regolith: Microwave versus direct solar heating

    NASA Technical Reports Server (NTRS)

    Kunitzer, J.; Strenski, D. G.; Yankee, S. J.; Pletka, B. J.

    1991-01-01

    The production of construction materials on the lunar surface will require an appropriate fabrication technique. Two processing methods considered as being suitable for producing dense, consolidated products such as bricks are direct solar heating and microwave heating. An analysis was performed to compare the two processes in terms of the amount of power and time required to fabricate bricks of various size. The regolith was considered to be a mare basalt with an overall density of 60 pct. of theoretical. Densification was assumed to take place by vitrification since this process requires moderate amounts of energy and time while still producing dense products. Microwave heating was shown to be significantly faster compared to solar furnace heating for rapid production of realistic-size bricks.

  6. Overview of current research opportunities in industrial microwave heating

    SciTech Connect

    Silberglitt, R.; Hien, L.K.; Rattien, S.

    1983-08-01

    The use of electromagnetic energy in industrial heating applications has many potential advantages as compared to conventional heating methods, e.g., increased energy efficiency, increased uniformity, lower product surface temperature, decreased space and production time requirements, and even improved product quality. However, industry has been slow to adopt this technique, especially as compared to the recent market penetration of consumer microwave ovens. This has been attributed to technological inertia, as well as the difficulty of demonstrating the cost-effectiveness of electromagnetic heating because at present most equipment must be custom-designed. Based upon a detailed survey of existing electromagnetic heating research and application areas, a number of research opportunities with significant technological innovation potential have been identified. These are reviewed, with emphasis on the microwave frequency range.

  7. Microwave-heating-coupled photoacoustic radar for tissue diagnostic imaging

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Mandelis, Andreas

    2016-06-01

    An investigation of microwave (MW) heating effects on biotissue for enhancing photoacoustic radar (PAR) signals was conducted. Localized tissue heating generated by MWs was used to improve PAR imaging depth and signal-to-noise ratio (SNR). Elevated temperatures were measured with thermocouples in ex vivo bovine muscle. The measured temperature rise on the heated spot surface by MWs was in agreement with theoretical predictions. The study showed localized MW heating can increase the photoacoustic imaging depth by 11%, and the SNR by 5% in ex vivo bovine muscle.

  8. Effects of polarization-charge shielding in microwave heating

    SciTech Connect

    Lin, M. S.; Lin, S. M.; Chiang, W. Y.; Barnett, L. R.; Chu, K. R.

    2015-08-15

    Heating of dielectric objects by radio frequency (RF) and microwaves has long been a method widely employed in scientific research and industrial applications. However, RF and microwave heating are often susceptible to an excessive temperature spread due to uneven energy deposition. The current study elucidates an important physical reason for this difficulty and proposes an effective remedy. Non-spherical samples are placed in an anechoic chamber, where it is irradiated by a traveling microwave wave with 99% intensity uniformity. Polarization charges induced on the samples tend to partially cancel the incident electric field and hence reduce the heating rate. The polarization-charge shielded heating rate is shown to be highly dependent on the sample's shape and its orientation relative to the wave electric field. For samples with a relatively high permittivity, the resultant uneven heating can become a major cause for the excessive temperature spread. It is also demonstrated that a circularly polarized wave, with its rapidly rotating electric field, can effectively even out the heating rate and hence the temperature spread.

  9. Apparatus with moderating material for microwave heat treatment of manufactured components

    DOEpatents

    Ripley, Edward B.

    2011-05-10

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  10. Ceramic-glass-ceramic seal by microwave heating

    DOEpatents

    Meek, T.T.; Blake, R.D.

    1983-10-04

    A method for producing a ceramic-glass-ceramic seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic workpieces. The slurry and workpieces are placed together, insulated and then microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by a diffusion rather than by wetting of the reactants.

  11. Ceramic-glass-metal seal by microwave heating

    DOEpatents

    Meek, T.T.; Blake, R.D.

    1983-10-04

    A method for producing a ceramic-glass-metal seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic and metal workpieces. The slurry and workpieces are then insulated and microwaved at a power, time and frequency sufficient to cause a liquid-phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by diffusion rather than by wetting of the reactants.

  12. Ceramic-glass-metal seal by microwave heating

    DOEpatents

    Meek, Thomas T.; Blake, Rodger D.

    1985-01-01

    A method for producing a ceramic-glass-metal seal by microwaving mixes a slurry of glass sealing material and coupling agent and applies same to ceramic and metal workpieces. The slurry and workpieces are then insulated and microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by diffusion rather than by wetting of the reactants.

  13. Ceramic-glass-ceramic seal by microwave heating

    DOEpatents

    Meek, Thomas T.; Blake, Rodger D.

    1985-01-01

    A method for producing a ceramic-glass-ceramic seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic workpieces. The slurry and workpieces are placed together, insulated and then microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by a diffusion rather than by wetting of the reactants.

  14. Effect of heating rate on evaporative heat loss in the microwave-exposed mouse

    SciTech Connect

    Gordon, C.J.

    1982-08-01

    Mice were exposed to microwave radiation at 2.450 MHz at varying intensities and heat loads to determine if the animals thermoregulate or temperature regulate in conditions of varying heat load. The mice were exposed to whole-body doses of microwave radiation and power not reflected back was regarded as absorbed by the mouse. Incident powers of three to six watts were used, resulting in specific absorption rates of 47.4-93.4 W/kg. Deep body temperatures and the evaporated heat loss were monitored, and results demonstrated that mice thermoregulate, i.e., dissipate heat loads through evaporative heat loss at a rate which is modeled numerically. It is concluded that a significant portion of the microwave energy is deposited internally.

  15. [Study on catalytic oxidation of benzene by microwave heating].

    PubMed

    Zhang, Yu-cai; Bo, Long-li; Wang, Xiao-hui; Liu, Hai-nan; Zhang, Hao

    2012-08-01

    The performance in catalytic oxidation of benzene was investigated in two different heating modes, microwave heating and conventional electric furnace heating. The effects of copper (Cu)-manganese (Mn) mass ratio, doping dose of cerium (Ce) and calcination temperature on the catalytic activity of Cu-Mn-Ce/molecular sieve catalyst were also checked in catalytic oxidation of benzene with microwave heating, and the catalysts were subsequently characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that the catalyst had better catalytic activity for the oxidation of benzene under microwave heating than electric furnace heating, and high oxidation efficiency for benzene was reached due to the "local hot spots" and dipole polarization effect of microwave and stable bed reaction temperature. Under the conditions of Cu, Mn and Ce mass ratio 1:1:0.33 and calcination temperature 500 degrees C, the catalyst had the optimal catalytic activity for benzene oxidation, and its light-off temperature and complete combustion temperature were 165 degrees C and 230 degrees C, respectively. It was indicated by characteristics of XRD and SEM that the presence of copper and manganese oxides and Cu1.5Mn1.5O4 with spinel crystal improved the catalytic activity of the catalyst, and the doping of Ce promoted the dispersion and regularization of active components. High calcination temperature led to the sintering of the catalyst surface and agglomeration of active components, which decreased the catalytic activity of the catalyst in the catalytic oxidation PMID:23213902

  16. Thermal runaway in microwave heated isothermal slabs, cylinders, and spheres

    NASA Astrophysics Data System (ADS)

    Vriezinga, C. A.

    1998-01-01

    The absorption of electromagnetic energy within a microwave heated isothermal slab, cylinder, and sphere is analyzed and compared to each other. It is shown that the absorbed heat oscillates as a function of temperature, regardless of the geometry of the irradiated object. It is possible to formulate this behavior in a simple mathematical equation, which proves that the oscillation is basically caused by resonance of the electromagnetic waves within the object. This oscillation, combined with the heat loss, is found to be responsible for thermal runaway phenomenon in isothermal objects. Based on such an observation, a general rule to prevent thermal runaway has been developed.

  17. Electrical conductivity of microwave heated polyaniline nanotubes and possible mechanism of microwave absorption by materials.

    PubMed

    Murai, Takahiro; Fukasawa, Ryo; Muraoka, Tohru; Takauchi, Hiroyuki; Gotoh, Yasuo; Takizawa, Tokihiro; Matsuse, Takehiro

    2009-01-01

    In the course of experiments to perform deprotonation and carbonization of doped polyaniline (PANI) nanotubes (NTs) by irradiating directly 2.45 GHz microwave (MW) in our microwave heating system (MWHS), we have discovered that the PANI-NTs self heat by absorbing the MW but the temperature of the PANI-NTs stops rising around 300 degrees C in spite of the heightened MW power Furthermore, we have found that the MW irradiated PANI-NTs have transferred from electrical conductor to insulator depending on the temperature of the PANI-NTs. By measuring electron spin resonance (ESR) spectra of the MW heated PANI-NTs, the existence of the unpaired electrons is shown to have a strong correlation between the degree of MW absorption and the transition in the electrical conductivities. In order to deprotonate and carbonize further the PANI-NTs, we have performed heat treatment for the PANI-NTs up to a temperature (T(HT)) of about 1200 degrees C in the same MWHS using carbon fiber which self heats by absorbing MW. The chemical transformations in the PANI-NTs induced by the heat treatments are discussed by measuring the X-ray photoelectron spectroscopy (XPS) spectra. Finally, the temperature dependence of electrical conductivities of the PANI-NTs are measured in order to investigate the mechanism of electrical conduction of the heat treated PANI-NTs. PMID:21384721

  18. DISTINCTION BETWEEN HEATING RATE AND TOTAL HEAT ABSORPTION IN THE MICROWAVE-EXPOSED MOUSE

    EPA Science Inventory

    This investigation assesses the ability of the heat-dissipating system of the mouse to respond to equivalent heat loads (e.g., J/g) administered at varying intensities (e.g., J/g/s or W/kg). Use of a microwave exposure system provided a means to administer exact amounts of energy...

  19. EFFECT OF HEATING RATE ON EVAPORATIVE HEAT LOSS IN THE MICROWAVE-EXPOSED MOUSE

    EPA Science Inventory

    Male CBA/J mice were administered heat loads of 0-28 J. per g at specific absorption rates (SARs) of either 47 or 93 W. per kg by exposure to 2,450-MHz microwave radiation at an ambient temperature of 30 C while evaporative heat loss (EHL) was continuously monitored with dew-poin...

  20. Plasma heating and current drive using intense, pulsed microwaves

    SciTech Connect

    Cohen, B.I.; Cohen, R.H.; Nevins, W.M.; Rognlien, T.D.; Bonoli, P.T.; Porkolab, M.

    1988-01-01

    The use of powerful new microwave sources, e.g., free-electron lasers and relativistic gyrotrons, provide unique opportunities for novel heating and current-drive schemes in the electron-cyclotron and lower-hybrid ranges of frequencies. These high-power, pulsed sources have a number of technical advantages over conventional, low-intensity sources; and their use can lead to improved current-drive efficiencies and better penetration into a reactor-grade plasma in specific cases. The Microwave Tokamak Experiment at Lawrence Livermore National Laboratory will provide a test for some of these new heating and current-drive schemes. This paper reports theoretical progress both in modeling absorption and current drive for intense pulses and in analyzing some of the possible complications that may arise, e.g., parametric instabilities and nonlinear self-focusing. 22 refs., 9 figs., 1 tab.

  1. Collaborational effect of heterolytic layered configuration for enhancement of microwave heating.

    PubMed

    Maitani, Masato M; Inoue, Tomoharu; Tsukushi, Yohei; Hansen, Niklas D J; Mochizuki, Dai; Suzuki, Eiichi; Wada, Yuji

    2013-11-28

    Microwave irradiation efficiently heats up the microwave-inert materials in the range of applied frequencies when two microwave-inert materials are brought into contact in the layered configuration. This heating is applied for annealing TiO2 nanoporous films for dye-sensitized solar cells achieving a one order of magnitude more rapid annealing process for comparable performances. PMID:24121483

  2. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., including microwave frequencies. 179.30 Section 179.30 Food and Drugs FOOD AND DRUG ADMINISTRATION... for the heating of food, including microwave frequencies. Radiofrequency radiation, including microwave frequencies, may be safely used for heating food under the following conditions: (a) The...

  3. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., including microwave frequencies. 179.30 Section 179.30 Food and Drugs FOOD AND DRUG ADMINISTRATION... for the heating of food, including microwave frequencies. Radiofrequency radiation, including microwave frequencies, may be safely used for heating food under the following conditions: (a) The...

  4. VENTILATORY FREQUENCY OF MOUSE AND HAMSTER DURING MICROWAVE-INDUCED HEAT EXPOSURE

    EPA Science Inventory

    Ventilatory frequency was recorded in unrestrained mice and hamsters using microwave radiation. The microwave exposure system was also used to impart varying heat loads to the rodents at ambient temperatures of 10, 20 and 30 C. The absorbed heat load accrued from microwave exposu...

  5. Structural characteristics of pumpkin pectin extracted by microwave heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To improve extraction yield of pumpkin pectin, microwave heating was adopted in this study. Using traditional hot acid extraction, pumpkin pectin yield decreased from 5.7 to 1.0 % as pH increased from pH 1.0 to 2.0. At pH 2.5, no pectin was recovered from pumpkin flesh powder. After a pre-treatment ...

  6. Modeling of well drilling heating on crude oil using microwave

    NASA Astrophysics Data System (ADS)

    Muntini, Melania Suweni; Pramono, Yono Hadi; Yustiana

    2016-03-01

    As the world's oil reserves are dwindling, some researchers have been prompted to make a breakthrough to further improve the efficiency of exploration and production. One of the technologies used is heating the crude oil. This paper presents the modeling results of heat treatment on crude oil using microwave energy. Modeling is conducted by assuming that the diameter of the well is 11,16 cm, the heat source is applied on the surface of the well, and the cut-off frequency in the air and on crude oil are 1,56 GHz. and 0.91 GHz, respectively. The energy generated by the microwave radiation is converted into heat energy which is absorbed by the crude oil. Consequently, this energy increases the temperature of crude oil through a heat transfer mechanism. The results obtained showed that the temperature of crude oil is about 200°C at a depth of 62.5cm, and at a distance of 3 cm from the center of the well. Temperature along the well follows an exponential function, which is from the center of the well in the direction radially outward from the cylinder axis. It has been observed that the temperature decreases as measured from the well surface along the cylinder.

  7. Viability and antigenicity of anisakis simplex after conventional and microwave heating at fixed temperatures.

    PubMed

    Vidaček, Sanja; De Las Heras, Cristina; Solas, Maria Teresa; García, Maria Luisa; Mendizábal, Angel; Tejada, Margarita

    2011-12-01

    Inactivation of parasites in food by microwave treatment may vary due to differences in the characteristics of microwave ovens and food properties. Microwave treatment in standard domestic ovens results in hot and cold spots, and the microwaves do not penetrate all areas of the samples depending on the thickness, which makes it difficult to compare microwave with conventional heat treatments. The viability of Anisakis simplex (isolated larvae and infected fish muscle) heated in a microwave oven with precise temperature control was compared with that of larvae heated in a water bath to investigate any additional effect of the microwaves. At a given temperature, less time was required to kill the larvae by microwaves than by heated water. Microwave treatment killed A. simplex larvae faster than did conventional cooking when the microwaves fully penetrated the samples and resulted in fewer changes in the fish muscle. However, the heat-stable allergen Ani s 4 was detected by immunohistochemistry in the fish muscle after both heat treatments, even at 70°C, suggesting that Ani s 4 allergens were released from the larvae into the surrounding tissue and that the tissues retained their allergenicity even after the larvae were killed by both heat treatments. Thus, microwave cooking will not render fish safe for individuals already sensitized to A. simplex heat-resistant allergens. PMID:22186053

  8. Microwave heating of aqueous samples on a micro-optical-electro-mechanical system

    DOEpatents

    Beer, Neil Reginald

    2016-04-12

    Apparatus for heating a sample includes a microchip; a microchannel flow channel in the microchip, the microchannel flow channel containing the sample; a microwave source that directs microwaves onto the sample for heating the sample; a wall section of the microchannel flow channel that receives the microwaves and enables the microwaves to pass through wall section of the microchannel flow channel, the wall section the microchannel flow channel being made of a material that is not appreciably heated by the microwaves; a carrier fluid within the microchannel flow channel for moving the sample in the microchannel flow channel, the carrier fluid being made of a material that is not appreciably heated by the microwaves; wherein the microwaves pass through wall section of the microchannel flow channel and heat the sample.

  9. Microwave heating of aqueous samples on a micro-optical-electro-mechanical system

    DOEpatents

    Beer, Neil Reginald

    2015-03-03

    Apparatus for heating a sample includes a microchip; a microchannel flow channel in the microchip, the microchannel flow channel containing the sample; a microwave source that directs microwaves onto the sample for heating the sample; a wall section of the microchannel flow channel that receives the microwaves and enables the microwaves to pass through wall section of the microchannel flow channel, the wall section the microchannel flow channel being made of a material that is not appreciably heated by the microwaves; a carrier fluid within the microchannel flow channel for moving the sample in the microchannel flow channel, the carrier fluid being made of a material that is not appreciably heated by the microwaves; wherein the microwaves pass through wall section of the microchannel flow channel and heat the sample.

  10. Progress on conformal microwave array applicators for heating chestwall disease

    NASA Astrophysics Data System (ADS)

    Stauffer, P. R.; Maccarini, P. F.; Juang, T.; Jacobsen, S. K.; Gaeta, C. J.; Schlorff, J. L.; Milligan, A. J.

    2007-02-01

    Previous studies have reported the computer modeling, CAD design, and theoretical performance of single and multiple antenna arrays of Dual Concentric Conductor (DCC) square slot radiators driven at 915 and 433 MHz. Subsequently, practical CAD designs of microstrip antenna arrays constructed on thin and flexible printed circuit board (PCB) material were reported which evolved into large Conformal Microwave Array (CMA) sheets that could wrap around the surface of the human torso for delivering microwave energy to large areas of superficial tissue. Although uniform and adjustable radiation patterns have been demonstrated from multiple element applicators radiating into simple homogeneous phantom loads, the contoured and heterogeneous tissue loads typical of chestwall recurrent breast cancer have required additional design efforts to achieve good coupling and efficient heating from the increasingly larger conformal array applicators used to treat large area contoured patient anatomy. Thus recent work has extended the theoretical optimization of DCC antennas to improve radiation efficiency of each individual aperture and reduce mismatch reflections, radiation losses, noise, and cross coupling of the feedline distribution network of large array configurations. Design improvements have also been incorporated into the supporting bolus structure to maintain effective coupling of DCC antennas into contoured anatomy and to monitor and control surface temperatures under the entire array. New approaches for non-invasive monitoring of surface and sub-surface tissue temperatures under each independent heat source are described that make use of microwave radiometry and flexible sheet grid arrays of thermal sensors. Efforts to optimize the clinical patient interface and move from planar rectangular shapes to contoured vest applicators that accommodate entire disease in a larger number of patients are summarized. By applying heat more uniformly to large areas of contoured anatomy

  11. Electron cyclotron resonance heating in the microwave tokamak experiment

    SciTech Connect

    Allen, S.L.; Casper, T.A.; Fenstermacher, M.E.

    1992-09-01

    This paper presents the results from a series of Electron Cyclotron Resonance Heating (ECRH) experiments on the Microwave Tokamak Experiment (MTX). On-axis heating at B{sub T} = 5T (f{sub ce} = 140 GHz) has been performed at electron densities up to cutoff. We have used both a long-pulse gryotron ({approximately}200 kW, {approximately}0.1s) and a pulsed Free Electron Laser (FEL) as microwave sources. Gyrotron experiments with power densities corresponding to 4 MW m{sup {minus}3}. A far infrared (FIR) polarimeter measured peaking of plasma current profiles in some discharges during the ECRH pulse. During high-power single-pulse FEL experiments, single-pass microwave !transmission measurements show nonlinear effects; i.e., higher transmission than predicted by linear theory. A corrugated-wall duct was used in the tokamak port to increase the gradient of the parallel refractive index n{sub parallel} of the incident wave, and increased absorption was observed. Evidence of electron tail heating during FEL pulses was observed on soft x-ray and ECE diagnostics. These results are in agreement with predictions of nonlinear theory; extrapolation of this theory to reactor-like conditions indicates efficient absorption and heating. A Laser Assisted Particle Probe Spectroscopy (LAPPS) diagnostic provided estimates of the vacuum electric field of the FEL which were consistent with the measured power. Multiple pulse operation of the ETA-II accelerator for the FEL has also been demonstrated, indicating the feasibility of high-average power FEL operation.

  12. Steady State Temperature Profile in a Cylinder Heated by Microwaves

    NASA Technical Reports Server (NTRS)

    Jackson, H. W.; Barmatz, M.; Wagner, P.

    1995-01-01

    A new theory has been developed to calculate the steady state temperature profile in a cylindrical sample positioned along the entire axis of a cylindrical microwave cavity. Temperature profiles where computed for- alumina rods of various radii contained in a cavity excite in one of the TM(sub OnO) modes with n = 1, 2 or 3. Calculations where also performed with a concentric outer cylindrical tube surrounding the rod to investigate hybrid heating. The parameters studies of the sample center and surface temperature where performed as a function of the total power transmitted into the cavity. Also, the total hemispherical emissivity was varied at boundaries of the rod, surrounding tube, and cavity walls. The result are discussed in the context of controlling the average rod temperature and the temperature distribution in the rod during microwave processing.

  13. Thawing of Frozen Dressed Tuna by Microwave Heating

    NASA Astrophysics Data System (ADS)

    Tanaka, Takeo; Nagasaki, Tasuku; Takahashi, Kenji

    Large sized frozen yellowfin tuna and southern bluefin tuna in dressed form (decapitated and gutted) were thawed by microwave (915 MHz) irradiation. Temperature rise of the tuna during thawing was measured. Quality of the tuna meat before and after thawing was compared with each other using objective quality index such as degree of discoloration (met-myoglobin ratio), freshness (K1 value) and taste cornponent (K2 value). Results are as follows : (1) Both frozen tunas were thawed fairly well within as short time as 30 min without any partial over heating. (2) No changes in met-myoglobin ratio, K1 and K2 values were observed in the cases of yellow fin tuna. Slight discoloration, however, occurred in southern bluefin tuna meat during microwave thawing. This problem has been left unsolved.

  14. Microwave heating and joining of ceramic cylinders: A mathematical model

    NASA Technical Reports Server (NTRS)

    Booty, Michael R.; Kriegsmann, Gregory A.

    1994-01-01

    A thin cylindrical ceramic sample is placed in a single mode microwave applicator in such a way that the electric field strength is allowed to vary along its axis. The sample can either be a single rod or two rods butted together. We present a simple mathematical model which describes the microwave heating process. It is built on the assumption that the Biot number of the material is small, and that the electric field is known and uniform throughout the cylinder's cross-section. The model takes the form of a nonlinear parabolic equation of reaction-diffusion type, with a spatially varying reaction term that corresponds to the spatial variation of the electromagnetic field strength in the waveguide. The equation is analyzed and a solution is found which develops a hot spot near the center of the cylindrical sample and which then propagates outwards until it stabilizes. The propagation and stabilization phenomenon concentrates the microwave energy in a localized region about the center where elevated temperatures may be desirable.

  15. Behavioral observations and operant procedures using microwaves as a heat source for young chicks

    SciTech Connect

    Morrison, W.D.; McMillan, I.; Bate, L.A.; Otten, L.; Pei, D.C.

    1986-08-01

    Four trials, using operant conditioning procedures, were conducted to study the response of chicks, housed at 16 C, to microwave or infrared heat. Microwave power density was 26 mW/cm2 in Trial 1, 13 mW/cm2 in Trial 2, and 10 mW/cm2 in Trials 3 and 4. Chicks voluntarily demanded between 28 and 63% as much heat (min heat/hr) from microwave source as from infrared source at all power densities. There was no correlation, however, between the ratio of heat demanded and the power density used. There were no significant differences in growth between infrared- or microwave-heated chicks. It is evident from these studies that 8-day-old broiler chicks are capable of associating the performance of a task with a thermal reward provided by the microwaves. They are also able to utilize these microwaves through operant conditioning without any visible detrimental effect to their health or behavior.

  16. Microwave heat treatment of natural ruby and its characterization

    NASA Astrophysics Data System (ADS)

    Swain, S.; Pradhan, S. K.; Jeevitha, M.; Acharya, P.; Debata, M.; Dash, T.; Nayak, B. B.; Mishra, B. K.

    2016-03-01

    Natural ruby (in the form of gemstone) collected from Odisha has been heat-treated by microwave (MW). A 3-kW industrial MW furnace with SiC susceptors was used for the heat treatment. The ruby samples showed noticeable improvements (qualitative), may be attributed to account for the improvement in clarity and lustre. Optical absorption in 200-800 nm range and photoluminescence peak at 693 nm (with 400 nm λ ex) clearly show that subtle changes do take place in the ruby after the heat treatment. Further, inorganic compound phases and valence states of elements (impurities) in the ruby were studied by X-ray diffraction, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The valence states of the main impurities such as Cr, Fe, and Ti, in the untreated and MW heat-treated ruby, as revealed from XPS, have been discussed in depth. The overall results demonstrate for the first time the effect of fast heating like MW on the microstructural properties of the gemstone and various oxidation states of impurity elements in the natural ruby.

  17. The utilization of microwave heating for the fabrication of sintered reaction-bonded silicon nitride

    SciTech Connect

    Kiggans, J.O.; Tiegs, T.N.; Lin, H.T.; Holcombe, C.E.

    1995-12-31

    The results of studies in which microwave heating was used to fabricate sintered reaction-bonded silicon nitride (SRBSN) are reviewed. These results are compared to parallel studies where conventional heating was used for the fabrication of these materials. Microwave fabrication of SRBSN involves a single heating cycle, whereas conventional processing requires two separate furnace runs and sample packaging steps. SRBSN containing high levels of sintering aids which were fabricated by microwave heating showed improved strength and toughness, as compared to those materials fabricated using a conventional resistance-heated furnace. An analysis of the microstructures of the microwave fabricated materials showed enhanced acicular grain growth as compared to conventionally heated material. Results are presented on studies involving the scale-up of the microwave fabrication process.

  18. Method for heat treating and sintering metal oxides with microwave radiation

    DOEpatents

    Holcombe, Cressie E.; Dykes, Norman L.; Meek, Thomas T.

    1989-01-01

    A method for microwave sintering materials, primarily metal oxides, is described. Metal oxides do not normally absorb microwave radiation at temperatures ranging from about room temperature to several hundred degrees centrigrade are sintered with microwave radiation without the use of the heretofore required sintering aids. This sintering is achieved by enclosing a compact of the oxide material in a housing or capsule formed of a oxide which has microwave coupling properties at room temprature up to at least the microwave coupling temperature of the oxide material forming the compact. The heating of the housing effects the initial heating of the oxide material forming the compact by heat transference and then functions as a thermal insulator for the encased oxide material after the oxide material reaches a sufficient temperature to adequately absorb or couple with microwave radiation for heating thereof to sintering temperature.

  19. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Radiofrequency radiation for the heating of food... FOOD Radiation and Radiation Sources § 179.30 Radiofrequency radiation for the heating of food, including microwave frequencies. Radiofrequency radiation, including microwave frequencies, may be...

  20. Comparison of glycation in conventionally and microwave-heated ovalbumin by high resolution mass spectrometry.

    PubMed

    Wang, Hui; Tu, Zong-Cai; Liu, Guang-Xian; Liu, Cheng-Mei; Huang, Xiao-Qin; Xiao, Hui

    2013-11-15

    The glycation extent of ovalbumin under two heating conditions, conventional and microwave heating was monitored by high resolution mass spectrometry, following pepsin digestion. The sequence coverage of the unglycated and glycated ovalbumin was 100% and 95%, respectively. About 35.2% of the lysines after microwave heating and 40.8% of the lysines after conventional heating were modified by d-glucose. The glycation content increased quickly when ovalbumin-glucose mixture was incubated for 15min, under both processing conditions. These modifications were slowed down after 30min of heating and no obvious advanced stage products were observed. The glycated peptides exhibited varying degrees of glycation, under both conventional and microwave heating, suggesting that glycation is strongly relevant to the protein structure. The fact that some peptides showed a lower level of glycation when heated by microwave indicated that microwave radiation might be a non-thermal process. In addition, the lack of browning after microwave heating emphasised the difference between microwave and conventional heating. PMID:23790877

  1. Application of microwave technology to the heat treatment of natural Youssoufia (Morocco) phosphates.

    PubMed

    Bilali, Latifa; Benchanaa, M; Outzourhit, A; Mokhlisse, A

    2009-01-01

    Microwave heating and conventional heating were used in the drying process of white phosphates and the pyrolysis of black phosphate. Microwave drying has been found to present faster kinetics, and the reaction mechanism is controlled by interfacial progression with a cylindrical symmetry for low powers and by diffusion for high microwave powers. Infrared thermography analysis shows that the heating mode is a function of the incident microwave power, the diameter of the reactor and the initial mass of the sample. The results of this study allowed us to understand the phenomena occurring during the microwave pyrolysis of black phosphate. Three temperature domains were revealed. Heating is attributed to the relaxation of polar molecules (water, polar organic molecules...) and to conduction losses of the different components of the phosphates and the products resulting from the decomposition of the mineral matrix as well as the carbon in the residues. Dielectric measurements at microwave frequencies showed that the dielectric constants (epsilon' and epsilon") decrease with time and reach values that are independent of the humidity of the phosphates, which correspond to the complete desorption of water. Cracks were observed in the microwave pyrolysis residues which also showed better cristallinity as revealed by SEM observation and XRD analysis. XPS analysis revealed for the fist time that the microwave pyrolysis residues contain less carbon than the residues of conventional heating, i.e. more oil is produced by microwave pyrolysis. PMID:21384713

  2. A comparison of microwave versus direct solar heating for lunar brick production

    NASA Technical Reports Server (NTRS)

    Yankee, S. J.; Strenski, D. G.; Pletka, B. J.; Patil, D. S.; Mutsuddy, B. C.

    1990-01-01

    Two processing techniques considered suitable for producing bricks from lunar regolith are examined: direct solar heating and microwave heating. An analysis was performed to compare the two processes in terms of the amount of power and time required to fabricate bricks of various sizes. Microwave heating was shown to be significantly faster than solar heating for rapid production of realistic-size bricks. However, the relative simplicity of the solar collector(s) used for the solar furnace compared to the equipment necessary for microwave generation may present an economic tradeoff.

  3. Observation of localized heating phenomena during microwave heating of mixed powders using in situ x-ray diffraction technique

    SciTech Connect

    Sabelström, N. Hayashi, M.; Watanabe, T.; Nagata, K.

    2014-10-28

    In materials processing research using microwave heating, there have been several observations of various phenomena occurring known as microwave effects. One significant example of such a phenomenon is increased reaction kinetics. It is believed that there is a possibility that this might be caused by localized heating, were some reactants would attain a higher than apparent temperature. To examine whether such thermal gradients are indeed possible, mixed powders of two microwave non-absorbers, alumina and magnesia, were mixed with graphite, a known absorber, and heated in a microwave furnace. During microwave irradiation, the local temperatures of the respective sample constituents were measured using an in situ x-ray diffraction technique. In the case of the alumina and graphite sample, a temperature difference of around 100 °C could be observed.

  4. Geometry for web microwave heating or drying to a desired profile in a waveguide

    DOEpatents

    Habeger, Jr., Charles C.; Patterson, Timothy F.; Ahrens, Frederick W.

    2005-11-15

    A microwave heater and/or dryer has a nonlinear or curvilinear relative slot profile geometry. In one embodiment, the microwave dryer has at least one adjustable field modifier making it possible to change the geometry of the heater or dryer when drying different webs. In another embodiment, the microwave dryer provides more uniform drying of a web when the field modifier is adjusted in response to a sensed condition of the web. Finally, a method of microwave heating and/or drying a web achieves a uniform heating and/or drying profile.

  5. Adjustments in metabolic heat production by squirrel monkeys exposed to microwaves

    SciTech Connect

    Adair, E.R.; Adams, B.W.

    1982-04-01

    The basic fact that microwave exposure can lower metabolic heat production has been previously demonstrated for the mouse by Ho and Edwards (1977) and for the rat by Phillips et al. (1975). The general conclusion drawn from both studies was that the metabolic reduction produced by microwave exposure was dose dependent. The present study extends the investigation into the effects of microwave exposure on metabolic heat production to a primate, the squirrel monkey. When squirrel monkeys are restrained in cool environments, body temperature is regulated by an increase in metabolic heat production. The results of the current study demonstrate that either brief or prolonged whole-body exposure to a microwave field will cause a reduction of this elevated heat production by an amount directly related to the microwave energy absorbed.

  6. Effect of microwave irradiation on selective heating behavior and magnetic separation characteristics of Panzhihua ilmenite

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Chen, Jin; Chang, Xiaodong; Guo, Shenghui; Srinivasakannan, C.; Chen, Guo; Peng, Jinhui

    2014-05-01

    The influences of microwave irradiation on the surface characteristics of Panzhihua ilmenite were systematically investigated. The crystal structures, surface morphology and surface chemical functional groups of ilmenite were characterized before and after microwave irradiation and magnetic separation for different microwave treatment times by using various methods, such as XRD, SEM, and FT-IR, respectively. XRD analysis showed that the microwave treated ilmenite has the strongest peaks of phase more than that of raw samples, indicates that the crystalline compound of ilmenite increased with the microwave irradiation time. SEM analysis showed the micro-cracking appeared at many grain boundaries of ilmenite after being pretreated by microwave treatment. The separations of ilmenite from gangue minerals were completed and the micro-fissure within ilmenite minerals were also formed, which could be attributed to the microwave selective heating characteristics of the different minerals and compounds, and the thermal stresses were caused by the uniform heat rate disturbed under microwave irradiation. The mineral processing results showed that the magnetic separation characteristics and properties of microwave treated ilmenite samples were better than that of microwave untreated ilmenite samples. It was concluded that microwave irradiation can be applied effectively and efficiently to the irradiation processes of Panzhihua ilmenite.

  7. Microwave heating: Industrial applications. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1995-12-01

    The bibliography contains citations concerning industrial uses and design of microwave heating equipment. Included are heating and drying of paper, industrial process heat, vulcanization, textile processing, metallurgical heat for sintering and ceramic manufacturing, food processing, and curing of polymers.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  8. Phase Transformation of VO2 Nanoparticles Assisted by Microwave Heating

    PubMed Central

    Sikong, Lek.

    2014-01-01

    The microwave assisted synthesis nowadays attracts a great deal of attention. Monoclinic phase VO2 (M) was prepared from NH4VO3 and H2C2O4 · 2H2O by a rapid microwave assisted technique. The synthesis parameters, microwave irradiation time, microwave power, and calcinations temperature were systematically varied and their influences on the structure and morphology were evaluated. The microwave power level has been carried out in range 180–600 W. TEM analysis demonstrated nanosized samples. The structural and morphological properties were measured using XRD, TEM, and thermal analyses. The variations of vanadium phase led to thermochromic properties. PMID:24688438

  9. Systematic Study of Microwave Absorption, Heating, and Microstructure Evolution of Porous Copper Powder Metal Compacts

    NASA Astrophysics Data System (ADS)

    Zimmerman, Darin; Diehl, John; Johnson, Earnie; Martin, Kelly; Miskovsky, Nicholas; Smith, Charles; Weisel, Gary; Weiss, Brock; Ma, Junkun

    2008-03-01

    We present a systematic study of the absorption, heating behavior, and microstructure evolution of porous copper powder metal powder compacts subjected to 2.45 GHz microwave radiation and explain our observations using known physical mechanisms. Using a single mode microwave system, we place the compacts in pure electric (E) or magnetic (H) fields and compare the heating trends. The observed trends in the E- and H-field heating reflect the dramatic changes in the conductivity, permittivity, and permeability of the samples caused by the microstructure evolution during heating in the two types of fields. The observed dependence of the initial microwave heating of the samples suggests that the microwave absorption in the sample is dominated by the properties of the individual metal particles composing the sample.

  10. Improvement of heating uniformity in packaged acidified vegetables pasteurized with a 915 MHz continuous microwave system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Continuous microwave processing to produce shelf-stable acidified vegetables with moderate to high salt contents poses challenges in pasteurization due to reduced microwave penetration depths and non-uniform heating. Cups of sweetpotato, red bell pepper, and broccoli acidified to pH 3.8 with citric...

  11. BEHAVIOURAL AND AUTONOMIC THERMOREGULATION IN HAMSTERS DURING MICROWAVE-INDUCED HEAT EXPOSURE

    EPA Science Inventory

    Preferred ambient temperature (Ta) and ventilatory frequency were measured in free-moving hamsters exposed to 2450 MHz microwaves. A waveguide exposure system which permits continuous monitoring of the absorbed heat load accrued from microwave exposure was imposed with a longitud...

  12. Microwave heating for production of a glass bonded ceramic high-level waste form.

    SciTech Connect

    O'Holleran, T. P.

    2002-07-30

    Argonne National Laboratory has developed a ceramic waste form to immobilize the salt waste from electrometallurgical treatment of spent nuclear fuel. The process is being scaled up to produce bodies of 100 Kg or greater. With conventional heating, heat transfer through the starting powder mixture necessitates long process times. Coupling of 2.45 GHz radiation to the starting powders has been demonstrated. The radiation couples most strongly to the salt occluded zeolite powder. The results of these experiments suggest that this ceramic waste form could be produced using microwave heating alone, or by using microwave heating to augment conventional heating.

  13. A Comparison of Direct Heating During Radiofrequency and Microwave Ablation in Ex Vivo Liver

    SciTech Connect

    Andreano, Anita; Brace, Christopher L.

    2013-04-15

    This study was designed to determine the magnitude and spatial distribution of temperature elevations when using 480 kHz RF and 2.45 GHz microwave energy in ex vivo liver models. A total of 60 heating cycles (20 s at 90 W) were performed in normal, RF-ablated, and microwave-ablated liver tissues (n = 10 RF and n = 10 microwave in each tissue type). Heating cycles were performed using a 480-kHz generator and 3-cm cooled-tip electrode (RF) or a 2.45-GHz generator and 14-gauge monopole (microwave) and were designed to isolate direct heating from each energy type. Tissue temperatures were measured by using fiberoptic thermosensors 5, 10, and 15 mm radially from the ablation applicator at the depth of maximal heating. Power delivered, sensor location, heating rates, and maximal temperatures were compared using mixed effects regression models. No significant differences were noted in mean power delivered or thermosensor locations between RF and microwave heating groups (P > 0.05). Microwaves produced significantly more rapid heating than RF at 5, 10, and 15 mm in normal tissue (3.0 vs. 0.73, 0.85 vs. 0.21, and 0.17 vs. 0.09 Degree-Sign C/s; P < 0.05); and at 5 and 10 mm in ablated tissues (2.3 {+-} 1.4 vs. 0.7 {+-} 0.3, 0.5 {+-} 0.3 vs. 0.2 {+-} 0 Degree-Sign C/s, P < 0.05). The radial depth of heating was {approx}5 mm greater for microwaves than RF. Direct heating obtained with 2.45-GHz microwave energy using a single needle-like applicator is faster and covers a larger volume of tissue than 480-kHz RF energy.

  14. A finite element method based microwave heat transfer modeling of frozen multi-component foods

    NASA Astrophysics Data System (ADS)

    Pitchai, Krishnamoorthy

    Microwave heating is fast and convenient, but is highly non-uniform. Non-uniform heating in microwave cooking affects not only food quality but also food safety. Most food industries develop microwavable food products based on "cook-and-look" approach. This approach is time-consuming, labor intensive and expensive and may not result in optimal food product design that assures food safety and quality. Design of microwavable food can be realized through a simulation model which describes the physical mechanisms of microwave heating in mathematical expressions. The objective of this study was to develop a microwave heat transfer model to predict spatial and temporal profiles of various heterogeneous foods such as multi-component meal (chicken nuggets and mashed potato), multi-component and multi-layered meal (lasagna), and multi-layered food with active packages (pizza) during microwave heating. A microwave heat transfer model was developed by solving electromagnetic and heat transfer equations using finite element method in commercially available COMSOL Multiphysics v4.4 software. The microwave heat transfer model included detailed geometry of the cavity, phase change, and rotation of the food on the turntable. The predicted spatial surface temperature patterns and temporal profiles were validated against the experimental temperature profiles obtained using a thermal imaging camera and fiber-optic sensors. The predicted spatial surface temperature profile of different multi-component foods was in good agreement with the corresponding experimental profiles in terms of hot and cold spot patterns. The root mean square error values of temporal profiles ranged from 5.8 °C to 26.2 °C in chicken nuggets as compared 4.3 °C to 4.7 °C in mashed potatoes. In frozen lasagna, root mean square error values at six locations ranged from 6.6 °C to 20.0 °C for 6 min of heating. A microwave heat transfer model was developed to include susceptor assisted microwave heating of a

  15. Effect of particle size and relative density on powdery Fe3O4 microwave heating.

    PubMed

    Hayashi, Miyuki; Yokoyama, Yuki; Nagata, Kazuhiro

    2010-01-01

    In recent years, microwave energy is expected to be a heat source of high temperature process aiming for CO2 reduction and energy conservation owing to the possibility of volumetric heating. In order to examine the applicability of microwave heating to ironmaking, it is important to investigate the microwave heating of raw materials of ironmaking such as Fe3O4. In this study, the effect of particle size and relative density on microwave absorptivity of powdery Fe3O4 was elucidated by the heating curves. Powdery Fe3O4 samples having different particle sizes and relative densities and bulk Fe3O4 samples were heated at the positions of the H (magnetic) and E (electric) field maxima in a 2.45 GHz single-mode microwave cavity. Sample temperatures abruptly increase and become constant after a while. At a constant temperature, the energy balance is attained, i.e., the rate of microwave energy absorption is equal to the rate of thermal energy dissipation. Assuming that the thermal energy dissipation rate due to convection and radiation heat fluxes is only a function of the sample temperature, the microwave absorptivity could be evaluated by the temperature at the steady state. It has been found that the microwave absorptivity of Fe3O4 powder decreases with an increase in relative density. On the other hand, the microwave absorptivity hardly depends on the particle size, which may be due to its quite a large penetration depth of Fe3O4 compared to metal. PMID:21721468

  16. Optimization and stabilization of gold nanoparticles by using herbal plant extract with microwave heating

    NASA Astrophysics Data System (ADS)

    Yasmin, Akbar; Ramesh, Kumaraswamy; Rajeshkumar, Shanmugam

    2014-04-01

    In this study, we have synthesized the gold nanoparticles by using Hibiscus rosa-sinensis, a medicinal plant. The gold nanoparticles were synthesized rapidly by the involvement of microwave heating. By changing of plant extract concentration, gold solution concentration, microwave heating time and power of microwave heating the optimized condition was identified. The surface Plasmon resonance found at 520 nm confirmed the gold nanoparticles synthesis. The spherical sized nanoparticles in the size range of 16-30 nm were confirmed by Transmission Electron Microscope (TEM). The stability of the nanoparticles is very well proved in the invitro stability tests. The biochemical like alkaloids and flavonoids play a vital role in the nanoparticles synthesis was identified using the Fourier Transform Infrared Spectroscopy (FTIR). Combining the phytochemical and microwave heating, the rapid synthesis of gold nanoparticles is the novel process for the medically applicable gold nanoparticles production.

  17. Furfural Synthesis from d-Xylose in the Presence of Sodium Chloride: Microwave versus Conventional Heating.

    PubMed

    Xiouras, Christos; Radacsi, Norbert; Sturm, Guido; Stefanidis, Georgios D

    2016-08-23

    We investigate the existence of specific/nonthermal microwave effects for the dehydration reaction of xylose to furfural in the presence of NaCl. Such effects are reported for sugars dehydration reactions in several literature reports. To this end, we adopted three approaches that compare microwave-assisted experiments with a) conventional heating experiments from the literature; b) simulated conventional heating experiments using microwave-irradiated silicon carbide (SiC) vials; and at c) different power levels but the same temperature by using forced cooling. No significant differences in the reaction kinetics are observed using any of these methods. However, microwave heating still proves advantageous as it requires 30 % less forward power compared to conventional heating (SiC vial) to achieve the same furfural yield at a laboratory scale. PMID:27416892

  18. MEASUREMENT OF MICROWAVE RADIATION ABSORBED BY BIOLOGICAL SYSTEMS. 1. ANALYSIS OF HEATING AND COOLING DATA

    EPA Science Inventory

    In order for meaningful comparisons to be made between experiments from different laboratories, reliable dosimetry is needed for biological systems exposed to microwave radiation. An improved analytical method is presented for determining energy absorption which uses heating and ...

  19. Microwave Heating of Functionalized Graphene Nanoribbons in Thermoset Polymers for Wellbore Reinforcement.

    PubMed

    Kim, Nam Dong; Metzger, Andrew; Hejazi, Vahid; Li, Yilun; Kovalchuk, Anton; Lee, Seoung-Ki; Ye, Ruquan; Mann, Jason A; Kittrell, Carter; Shahsavari, Rouzbeh; Tour, James M

    2016-05-25

    Here, we introduce a systematic strategy to prepare composite materials for wellbore reinforcement using graphene nanoribbons (GNRs) in a thermoset polymer irradiated by microwaves. We show that microwave absorption by GNRs functionalized with poly(propylene oxide) (PPO-GNRs) cured the composite by reaching 200 °C under 30 W of microwave power. Nanoscale PPO-GNRs diffuse deep inside porous sandstone and dramatically enhance the mechanics of the entire structure via effective reinforcement. The bulk and the local mechanical properties measured by compression and nanoindentation mechanical tests, respectively, reveal that microwave heating of PPO-GNRs and direct polymeric curing are major reasons for this significant reinforcement effect. PMID:27140722

  20. Microwave heating of a Ba photoplasma in free expansion into a vacuum

    SciTech Connect

    Furtlehner, J.P.; Blanchet, A.; Leloutre, B.

    1995-12-31

    The microwave heating of a pulsed Ba photoplasma and its free expansion into a vacuum is studied theoretically and experimentally. The vapor production apparatus and the two step photoionization scheme have been described in a previous paper. The heating experimental device is essentially a microwave loop working in a self tuning oscillator mode composed of a transmission rectangular microwave resonator associated with a TWT power amplifier. The amplifier is coupled to the rectangular resonator by two coaxial-line probes: with a coupling coefficient very close to 1 at the input and with a coefficient equal about 10{sup -3} at the output.

  1. Electromagnetic simulations of microwave heating experiments using reaction vessels made out of silicon carbide.

    PubMed

    Robinson, John; Kingman, Sam; Irvine, Derek; Licence, Peter; Smith, Alastair; Dimitrakis, Georgios; Obermayer, David; Kappe, C Oliver

    2010-09-28

    There is a growing body of literature which reports the use of silicon carbide vessels to shield reaction mixtures during microwave heating. In this paper we use electromagnetic simulations and microwave experiments to show that silicon carbide vessels do not exclude the electric field, and that dielectric heating of reaction mixtures will take place in addition to heat transfer from the silicon carbide. The contribution of dielectric heating and heat transfer depends on the dielectric properties of the mixture, and the temperature at which the reaction is carried out. Solvents which remain microwave absorbent at high temperatures, such as ionic liquids, will heat under the direct influence of the electric field from 30-250 degrees C. Solvents which are less microwave absorbent at higher temperatures will be heated by heat-transfer only at temperatures in excess of 150 degrees C. The results presented in this paper suggest that the influence of the electric field cannot be neglected when interpreting microwave assisted synthesis experiments in silicon carbide vessels. PMID:20625593

  2. Microwave Heating of TV-Dinner Type Products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Modified from an inverter-based microwave oven, a new microwave system was developed to pasteurize mechanically tenderized beef, inoculated with Escherichia coli O157:H7 and placed into a 12 oz CPET tray containing de-ionized water. The system allowed the sample surface temperature to first increas...

  3. Simple method for highlighting the temperature distribution into a liquid sample heated by microwave power field

    SciTech Connect

    Surducan, V.; Surducan, E.; Dadarlat, D.

    2013-11-13

    Microwave induced heating is widely used in medical treatments, scientific and industrial applications. The temperature field inside a microwave heated sample is often inhomogenous, therefore multiple temperature sensors are required for an accurate result. Nowadays, non-contact (Infra Red thermography or microwave radiometry) or direct contact temperature measurement methods (expensive and sophisticated fiber optic temperature sensors transparent to microwave radiation) are mainly used. IR thermography gives only the surface temperature and can not be used for measuring temperature distributions in cross sections of a sample. In this paper we present a very simple experimental method for temperature distribution highlighting inside a cross section of a liquid sample, heated by a microwave radiation through a coaxial applicator. The method proposed is able to offer qualitative information about the heating distribution, using a temperature sensitive liquid crystal sheet. Inhomogeneities as smaller as 1°-2°C produced by the symmetry irregularities of the microwave applicator can be easily detected by visual inspection or by computer assisted color to temperature conversion. Therefore, the microwave applicator is tuned and verified with described method until the temperature inhomogeneities are solved.

  4. An optical fiber sensing technique for temperature distribution measurements in microwave heating

    NASA Astrophysics Data System (ADS)

    Wada, Daichi; Sugiyama, Jun-ichi; Zushi, Hiroaki; Murayama, Hideaki

    2015-08-01

    We introduce an optical fiber sensing technique that can measure the temperature distributions along a fiber during microwave heating. We used a long-length fiber Bragg grating (FBG) as an electromagnetic-immune sensor and interrogated temperature distributions along the FBG by an optical frequency domain reflectometry. Water in a glass tube with a length of 820 mm was heated in a microwave oven, and its temperature distribution along the glass tube was measured using the sensing system. The temperature distribution was obtained in 5 mm intervals. Infrared radiometry was also used to compare the temperature measurement results. Time and spatial variations of the temperature distribution profiles were monitored for several microwave input powers. The results clearly depict inhomogeneous temperature profiles. The applicability and effectiveness of the optical fiber distributed measurement technique in microwave heating are demonstrated.

  5. Microwave heating device for internal heating convection experiments, applied to Earth's mantle dynamics.

    PubMed

    Surducan, E; Surducan, V; Limare, A; Neamtu, C; Di Giuseppe, E

    2014-12-01

    We report the design, construction, and performances of a microwave (MW) heating device for laboratory experiments with non-contact, homogeneous internal heating. The device generates MW radiation at 2.47 GHz from a commercial magnetron supplied by a pulsed current inverter using proprietary, feedback based command and control hardware and software. Specially designed MW launchers direct the MW radiation into the sample through a MW homogenizer, devised to even the MW power distribution into the sample's volume. An adjustable MW circuit adapts the MW generator to the load (i.e., the sample) placed in the experiment chamber. Dedicated heatsinks maintain the MW circuits at constant temperature throughout the experiment. Openings for laser scanning for image acquisition with a CCD camera and for the cooling circuits are protected by special MW filters. The performances of the device are analyzed in terms of heating uniformity, long term output power stability, and load matching. The device is used for small scale experiments simulating Earth's mantle convection. The 30 × 30 × 5 cm(3) convection tank is filled with a water‑based viscous fluid. A uniform and constant temperature is maintained at the upper boundary by an aluminum heat exchanger and adiabatic conditions apply at the tank base. We characterize the geometry of the convective regime as well as its bulk thermal evolution by measuring the velocity field by Particle Image Velocimetry and the temperature field by using Thermochromic Liquid Crystals. PMID:25554309

  6. Microwave heating device for internal heating convection experiments, applied to Earth's mantle dynamics

    NASA Astrophysics Data System (ADS)

    Surducan, E.; Surducan, V.; Limare, A.; Neamtu, C.; Di Giuseppe, E.

    2014-12-01

    We report the design, construction, and performances of a microwave (MW) heating device for laboratory experiments with non-contact, homogeneous internal heating. The device generates MW radiation at 2.47 GHz from a commercial magnetron supplied by a pulsed current inverter using proprietary, feedback based command and control hardware and software. Specially designed MW launchers direct the MW radiation into the sample through a MW homogenizer, devised to even the MW power distribution into the sample's volume. An adjustable MW circuit adapts the MW generator to the load (i.e., the sample) placed in the experiment chamber. Dedicated heatsinks maintain the MW circuits at constant temperature throughout the experiment. Openings for laser scanning for image acquisition with a CCD camera and for the cooling circuits are protected by special MW filters. The performances of the device are analyzed in terms of heating uniformity, long term output power stability, and load matching. The device is used for small scale experiments simulating Earth's mantle convection. The 30 × 30 × 5 cm3 convection tank is filled with a water-based viscous fluid. A uniform and constant temperature is maintained at the upper boundary by an aluminum heat exchanger and adiabatic conditions apply at the tank base. We characterize the geometry of the convective regime as well as its bulk thermal evolution by measuring the velocity field by Particle Image Velocimetry and the temperature field by using Thermochromic Liquid Crystals.

  7. Microwave heating device for internal heating convection experiments, applied to Earth's mantle dynamics

    SciTech Connect

    Surducan, E.; Surducan, V.; Neamtu, C.; Limare, A.; Di Giuseppe, E.

    2014-12-15

    We report the design, construction, and performances of a microwave (MW) heating device for laboratory experiments with non-contact, homogeneous internal heating. The device generates MW radiation at 2.47 GHz from a commercial magnetron supplied by a pulsed current inverter using proprietary, feedback based command and control hardware and software. Specially designed MW launchers direct the MW radiation into the sample through a MW homogenizer, devised to even the MW power distribution into the sample's volume. An adjustable MW circuit adapts the MW generator to the load (i.e., the sample) placed in the experiment chamber. Dedicated heatsinks maintain the MW circuits at constant temperature throughout the experiment. Openings for laser scanning for image acquisition with a CCD camera and for the cooling circuits are protected by special MW filters. The performances of the device are analyzed in terms of heating uniformity, long term output power stability, and load matching. The device is used for small scale experiments simulating Earth's mantle convection. The 30 × 30 × 5 cm{sup 3} convection tank is filled with a water‑based viscous fluid. A uniform and constant temperature is maintained at the upper boundary by an aluminum heat exchanger and adiabatic conditions apply at the tank base. We characterize the geometry of the convective regime as well as its bulk thermal evolution by measuring the velocity field by Particle Image Velocimetry and the temperature field by using Thermochromic Liquid Crystals.

  8. Low-power microwave-mediated heating for microchip-based PCR.

    PubMed

    Marchiarullo, Daniel J; Sklavounos, Angelique H; Oh, Kyudam; Poe, Brian L; Barker, N Scott; Landers, James P

    2013-09-01

    Microwave energy has been used to rapidly heat food and drinks for decades, in addition to assisting other chemical reactions. However, only recently has microwave energy been applied in microfluidic systems to heat solution in reaction chambers, in particular, the polymerase chain reaction (PCR). One of the difficulties in developing microwave-mediated heating on a microchip is the construction of the appropriate architecture for delivery of the energy to specific micro-areas on the microchip. This work employs commercially-available microwave components commonly used in the wireless communications industry to generate a microwave signal, and a microstrip transmission line to deliver the energy to a 1 μL reaction chamber fabricated in plastic microdevices. A model was developed to create transmission lines that would optimally transmit energy to the reaction chamber at a given frequency, minimizing energy usage while focusing microwave delivery to the target chamber. Two different temperature control methods were demonstrated, varying microwave power or frequency. This system was used to amplify a fragment of the lambda-phage genome, thereby demonstrating its potential for integration into a portable PCR system. PMID:23843031

  9. Behavioral and autonomic thermoregulation in hamsters during microwave-induced heat exposure

    SciTech Connect

    Gordon, C.J.; Long, M.D.; Fehlner, K.S.

    1984-01-01

    Preferred ambient temperature (Ta) and ventilatory frequency were measured in free-moving hamsters exposed to 2450-MHz microwaves. A waveguide exposure system that permits continuous monitoring of the absorbed heat load accrued from microwave exposure was imposed with a longitudinal temperature gradient which allowed hamsters to select their preferred Ta. Ventilatory frequency was monitored remotely by analysing the rhythmic shifts in unabsorbed microwave energy passing down the waveguide. Without microwave exposure hamsters selected an average T2 of 30.2 C. This preferred Ta did not change until the rate of heat absorption (SAR) from microwave exposure exceeded approx. 2 W kg-1. In a separate experiment, a SAR of 2.0 W kg-1 at a Ta of 30C was shown to promote an average 0.5 C increase in colonic temperature. Hamsters maintained their ventilatory frequency at baseline levels by selecting a cooler Ta during microwave exposure. These data support previous studies suggesting that during thermal stress behavioral thermo-regulation (i.e. preferred Ta) takes prescedence over autonomic thermoregulation (i.e. ventilatory frequency). It is apparent that selecting a cooler Ta is a more efficient and/or effective than autonomic thermoregulation for dissipating a heat load accrued from microwave exposure.

  10. Method for curing polymers using variable-frequency microwave heating

    DOEpatents

    Lauf, R.J.; Bible, D.W.; Paulauskas, F.L.

    1998-02-24

    A method for curing polymers incorporating a variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity is disclosed. By varying the frequency of the microwave signal, non-uniformities within the cavity are minimized, thereby achieving a more uniform cure throughout the workpiece. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. The furnace cavity may be adapted to be used to cure materials defining a continuous sheet or which require compressive forces during curing. 15 figs.

  11. Method for curing polymers using variable-frequency microwave heating

    DOEpatents

    Lauf, Robert J.; Bible, Don W.; Paulauskas, Felix L.

    1998-01-01

    A method for curing polymers (11) incorporating a variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34). By varying the frequency of the microwave signal, non-uniformities within the cavity (34) are minimized, thereby achieving a more uniform cure throughout the workpiece (36). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. The furnace cavity (34) may be adapted to be used to cure materials defining a continuous sheet or which require compressive forces during curing.

  12. Microwave heating in peptide side chain modification via cysteine alkylation.

    PubMed

    Calce, Enrica; De Luca, Stefania

    2016-09-01

    Microwave irradiation has been successfully applied to a selective synthetic procedure for introducing molecular substituents on peptides, providing a noticeable reduction of the reaction time and also an increased crude peptide purity for some compounds. PMID:27351201

  13. Vesicouretal reflux in children: A phantom study of microwave heating and radiometric thermometry of pediatric bladder

    PubMed Central

    Birkelund, Yngve; Klemetsen, Øystein; Jacobsen, Svein K.; Arunachalam, Kavitha; Maccarini, Paolo; Stauffer, Paul R.

    2012-01-01

    We have investigated the use of microwave heating and radiometry to safely heat urine inside a pediatric bladder. The medical application for this research is to create a safe and reliable method to detect vesicoureteral reflux, a pediatric disorder, where urine flow is reversed and flows from the bladder back up into the kidney. Using fat and muscle tissue models, we have performed both experimental and numerical simulations of a pediatric bladder model using planar dual concentric conductor microstrip antennas at 915 MHz for microwave heating. A planar elliptical antenna connected to a 500 MHz bandwidth microwave radiometer centered at 3.5 GHz was used for non-invasive temperature measurement inside tissue. Temperatures were measured in the phantom models at points during the experiment with implanted fiberoptic sensors, and 2D distributions in cut planes at depth in the phantom with an infrared camera at the end of the experiment. Cycling between 20 second with 20 Watts power for heating, and 10 seconds without power to allow for undisturbed microwave radiometry measurements, the experimental results show that the target tissue temperature inside the phantom increases fast and that the radiometer provides useful measurements of spatially averaged temperature of the illuminated volume. The presented numerical and experimental results show excellent concordance, which confirms that the proposed system for microwave heating and radiometry is applicable for safe and reliable heating of pediatric bladder. PMID:21900069

  14. Nucleation and crystallization of tailing-based glass-ceramics by microwave heating

    NASA Astrophysics Data System (ADS)

    Li, Bao-wei; Li, Hong-xia; Zhang, Xue-feng; Jia, Xiao-lin; Sun, Zhi-chao

    2015-12-01

    The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared from Shandong gold tailings and Guyang iron tailings utilizing a conventional glass melting technique. For comparison, the tailing-based glass samples were crystallized using two different heat-treatment methods: conventional heating and hybrid microwave heating. The nucleation and crystallization temperatures were determined by performing a differential thermal analysis of the quenched tailing-based glass. The prepared glass-ceramic samples were further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermal expansion coefficient measurements, and scanning electron microscopy. The results demonstrated that hybrid microwave heating could be successfully used to crystallize the tailing-based glass, reduce the processing time, and decrease the crystallization temperature. Furthermore, the results indicated that the nucleation and crystallization mechanism of the hybrid microwave heating process slightly differs from that of the conventional heating process.

  15. Vesicoureteral reflux in children: a phantom study of microwave heating and radiometric thermometry of pediatric bladder.

    PubMed

    Birkelund, Yngve; Klemetsen, Øystein; Jacobsen, Svein K; Arunachalam, Kavitha; Maccarini, Paolo; Stauffer, Paul R

    2011-11-01

    We have investigated the use of microwave heating and radiometry to safely heat urine inside a pediatric bladder. The medical application for this research is to create a safe and reliable method to detect vesicoureteral reflux, a pediatric disorder, where urine flow is reversed and flows from the bladder back up into the kidney. Using fat and muscle tissue models, we have performed both experimental and numerical simulations of a pediatric bladder model using planar dual concentric conductor microstrip antennas at 915 MHz for microwave heating. A planar elliptical antenna connected to a 500 MHz bandwidth microwave radiometer centered at 3.5 GHz was used for noninvasive temperature measurement inside tissue. Temperatures were measured in the phantom models at points during the experiment with implanted fiberoptic sensors, and 2-D distributions in cut planes at depth in the phantom with an infrared camera at the end of the experiment. Cycling between 20 s with 20 Watts power for heating, and 10 s without power to allow for undisturbed microwave radiometry measurements, the experimental results show that the target tissue temperature inside the phantom increases fast and that the radiometer provides useful measurements of spatially averaged temperature of the illuminated volume. The presented numerical and experimental results show excellent concordance, which confirms that the proposed system for microwave heating and radiometry is applicable for safe and reliable heating of pediatric bladder. PMID:21900069

  16. Effects of microwave heating on porous structure of regenerated powdered activated carbon used in xylose.

    PubMed

    Li, Wei; Wang, Xinying; Peng, Jinhui

    2014-01-01

    The regeneration of spent powdered activated carbons used in xylose decolourization by microwave heating was investigated. Effects of microwave power and microwave heating time on the adsorption capacity of regenerated activated carbons were evaluated. The optimum conditions obtained are as follows: microwave power 800W; microwave heating time 30min. Regenerated activated carbon in this work has high adsorption capacities for the amount of methylene blue of 16 cm3/0.1 g and the iodine number of 1000.06mg/g. The specific surface areas of fresh commercial activated carbon, spent carbon and regenerated activated carbon were calculated according to the Brunauer, Emmett and Teller method, and the pore-size distributions of these carbons were characterized by non-local density functional theory (NLDFT). The results show that the specific surface area and the total pore volume of regenerated activated carbon are 1064 m2/g and 1.181 mL/g, respectively, indicating the feasibility of regeneration of spent powdered activated carbon used in xylose decolourization by microwave heating. The results of surface fractal dimensions also confirm the results of isotherms and NLDFT. PMID:24645431

  17. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Radiofrequency radiation for the heating of food... PRODUCTION, PROCESSING AND HANDLING OF FOOD Radiation and Radiation Sources § 179.30 Radiofrequency radiation for the heating of food, including microwave frequencies. Radiofrequency radiation,...

  18. 21 CFR 179.30 - Radiofrequency radiation for the heating of food, including microwave frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Radiofrequency radiation for the heating of food... PRODUCTION, PROCESSING AND HANDLING OF FOOD Radiation and Radiation Sources § 179.30 Radiofrequency radiation for the heating of food, including microwave frequencies. Radiofrequency radiation,...

  19. A Half Century of Research on Agricultural Applications for RF and Microwave Dielectric Heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Basic principles of radio-frequency and microwave dielectric heating are presented, and research reports and reviews published over the past 50 or 60 years are identified for various dielectric heating applications that have been explored for potential use in the field of agriculture. Included are ...

  20. Microwave heating: Industrial applications. (Latest citations from the EI Compendex*plus database). Published Search

    SciTech Connect

    1996-04-01

    The bibliography contains citations concerning industrial uses and design of microwave heating equipment. Citations discuss applications in food processing, industrial heating, vulcanization, textile finishing, metallurgical sintering, ceramic manufacturing, paper industries, and curing of polymers. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  1. Evaluation the microwave heating of spinel crystals in high-level waste glass

    SciTech Connect

    Christian, J. H.; Washington, A. L.

    2015-08-18

    In this report, the microwave heating of a crystal-free and a partially (24 wt%) trevorite-crystallized waste glass simulant were evaluated. The results show that a 500 mg piece of partially crystallized waste glass can be heated from room-temperature to above 1600 °C (as measured by infrared radiometry) within 2 minutes using a single mode, highly focused, 2.45 GHz microwave, operating at 300 W. X-ray diffraction measurements show that the partially crystallized glass experiences an 87 % reduction in trevorite following irradiation and thermal quenching. When a crystal-free analogue of the same waste glass simulant composition is exposed to the same microwave radiation it could not be heated above 450 °C regardless of the heating time.

  2. Effects of microwave radiation and conductive heating on Tribolium castaneum microstructure.

    PubMed

    Lu, H H; Zhou, J C; Yan, D; Zhao, S M; Xiong, S B

    2011-01-01

    Microwave radiation and conductive heating were used to completely kill adult Tribolium castaneum (Coleoptera: Tenebrionidae) in wheat flour to protect the flour during storage without significantly effecting its quality. The microstructure of T. castaneum was analyzed to reveal the mechanisms leading to death under microwave and heat treatments. Microwave radiation and conductive heating had different effects on the microstructure of the cuticle of adult T. castaneum and on the ultrastructure of the cells of the epidermis, fat body, and midgut. Both treatments caused a large cavity to appear in the nucleus and the disappearance of mitochondria and the Golgi apparatus. After microwave treatment, there was little change in the surface microstructure but the epidermis was of uneven thickness and the four outer layers of the cuticle were thinner. Nuclear size was essentially unchanged, but fat body cells were fewer and coalesced together. In contrast, conductive heating led to a disordered arrangement of cells on the surface of T. castaneum and indistinct boundaries between layers of the cuticle. The nuclei were enlarged and the fat body cells noticeably fewer and indistinct with a scattered distribution. Thus, microwave treatment produced less severe effects on the surface microstructure and cellular ultrastructure of T. castaneum than did conductive heating. It is concluded that these cellular and surface changes were responsible for the death of T. castaneum. PMID:20837396

  3. Microwave heating enhances antioxidant and emulsifying activities of ovalbumin glycated with glucose in solid-state.

    PubMed

    Tu, Zong-Cai; Hu, Yue-Ming; Wang, Hui; Huang, Xiao-Qin; Xia, Shi-Qi; Niu, Pei-Pei

    2015-03-01

    The aim of this study was to characterize the properties of ovalbumin (OVA) after glycated with glucose under microwave heating. For this purpose, microwave at 480 and 640 W power levels were used for heating the OVA-glucose system in solid-state for 0, 5, 10, 15, 20 and 25 min, respectively. The results indicated that the protein molecular weight was increased after glycated with glucose under microwave treatment, the pH of the system was decreased with the increase of microwave treatment power and time, while the UV absorbance, browning intensity, antioxidant activities as well as the emulsifying activity and emulsion stability of the Maillard reaction products (MRPs) were increased in according with the raise of microwave treatment power and time. The reaction time of microwave treatment is much shorter than those using traditional methods, suggesting that microwave irradiation is a novel and efficient approach to promote Maillard reaction (MR) in dry state and improve protein antioxidant and functional properties. PMID:25745213

  4. Processing and characterization of a polymer matrix composite using variable frequency microwave heating

    SciTech Connect

    Fathi, Z.; Garard, R.S.; DeMeuse, M.T.

    1995-12-31

    Variable frequency microwave energy was successfully applied to uniformly heat thermoset polymer matrix composite (PMC) materials consisting of glass-reinforced isocyanate/epoxy mixtures as well as graphite fiber-reinforced epoxy. Results of a series of materials processed via variable frequency microwave energy are compared with computed results from numerical modeling techniques. A finite difference time domain (FDTD) technique provides 2-D models of the electric and thermal field distributions inside the microwave cavity as well as inside the processed materials. The materials` physical and chemical characteristics from the empirical trials are evaluated for both variable and fixed frequency irradiation.

  5. Microwave-based, internally-heated convection: New perspectives for the heterogeneous case

    NASA Astrophysics Data System (ADS)

    Limare, A.; Fourel, L.; Surducan, E.; Neamtu, C.; Surducan, V.; Vilella, K.; Farnetani, C. G.; Kaminski, E.; Jaupart, C.

    2015-12-01

    The thermal evolution of telluric planets is primarily controlled by the balance between internal heating - due to ra-dioactive decay - and effciency of convective heat transfer in their mantle. In the Earth, the problem is particularly complex due to the heterogeneous distribution of heat sources in the mantle and the non-linear coupling between this distribution and convective mixing. To tackle this issue, we have developed a new technology to produce internally-heated convection based on microwaves absorption. This technology has the unique capability to selectively heat different zones of a convective fluid (heterogeneous convection) through the careful control of the absorption properties of the different fluids. Here we illustrate with two examples the new geophysical perspectives offered by microwave-based internally-heated convection: the problem of lithosphere stability and the evolution of a hidden enriched reservoir in the lowermost mantle.

  6. Understanding microwave heating effects in single mode type cavities-theory and experiment.

    PubMed

    Robinson, John; Kingman, Sam; Irvine, Derek; Licence, Peter; Smith, Alastair; Dimitrakis, Georgios; Obermayer, David; Kappe, C Oliver

    2010-05-14

    This paper explains the phenomena which occur in commercially available laboratory microwave equipment, and highlights several situations where experimental observations are often misinterpreted as a 'microwave effect'. Electromagnetic simulations and heating experiments were used to show the quantitative effects of solvent type, solvent volume, vessel material, vessel internals and stirring rate on the distribution of the electric field, the power density and the rate of heating. The simulations and experiments show how significant temperature gradients can exist within the heated materials, and that very different results can be obtained depending on the method used to measure temperature. The overall energy balance is shown for a number of different solvents, and the interpretation and implications of using the results from commercially available microwave equipment are discussed. PMID:20428555

  7. Potential of Microwave Heating as a Pasteurization Method for Almonds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pasteurization of almonds to reduce the risk of Salmonella contamination is an objective of the almond industry. Microwave (MW) technology may generate almond surface temperatures effective in reduction of Salmonella. This study was conducted to examine almond surface and internal temperatures gener...

  8. Conductive heating and microwave hydrolysis under identical heating profiles for advanced anaerobic digestion of municipal sludge.

    PubMed

    Mehdizadeh, Seyedeh Neda; Eskicioglu, Cigdem; Bobowski, Jake; Johnson, Thomas

    2013-09-15

    Microwave (2.45 GHz, 1200 W) and conventional heating (custom pressure vessel) pretreatments were applied to dewatered municipal waste sludge (18% total solids) using identical heating profiles that span a wide range of temperatures (80-160 °C). Fourteen lab-scale semi-continuous digesters were set up to optimize the energy (methane) output and sludge retention time (SRT) requirements of untreated (control) and thermally pretreated anaerobic digesters operated under mesophilic and thermophilic temperatures. Both pretreatment methods indicated that in the pretreatment range of 80-160 °C, temperature was a statistically significant factor (p-value < 0.05) for increasing solubilization of chemical oxygen demand and biopolymers (proteins, sugars, humic acids) of the waste sludge. However, the type of pretreatment method, i.e. microwave versus conventional heating, had no statistically significant effect (p-value >0.05) on sludge solubilization. With the exception of the control digesters at a 5-d SRT, all control and pretreated digesters achieved steady state at all three SRTs, corresponding to volumetric organic loading rates of 1.74-6.96 g chemical oxygen demand/L/d. At an SRT of 5 d, both mesophilic and thermophilic controls stopped producing biogas after 20 d of operation with total volatile fatty acids concentrations exceeding 1818 mg/L at pH <5.64 for mesophilic and 2853 mg/L at pH <7.02 for thermophilic controls, while the pretreated digesters continued producing biogas. Furthermore, relative (to control) organic removal efficiencies dramatically increased as SRT was shortened from 20 to 10 and then 5 d, indicating that the control digesters were challenged as the organic loading rate was increased. Energy analysis showed that, at an elevated temperature of 160 °C, the amount of methane recovered was not enough to compensate for the energy input. Among the digesters with positive net energy productions, control and pretreated digesters at 80 °C were more

  9. Surface-plasmon-like modes of graphite powder compact in microwave heating

    NASA Astrophysics Data System (ADS)

    Kashimura, K.; Suzuki, S.; Hayashi, M.; Mitani, T.; Shinohara, N.; Nagata, K.

    2012-08-01

    We determine the mechanism of rapid and selective heating of nonmagnetic conductive particles by the electric and magnetic fields of microwaves. We investigated the dependencies of the heating behaviors of carbon powders on the radius and electrical conductivity for various relative densities. In these experiments, strong microwave absorption was observed in magnetic field at certain radii and ratios of the crystallite size to the radius. Mie theory for a single particle could account for the high heating rates generated by the microwave magnetic field in sintering experiments. In the dependence of the heating behavior on the relative density, that H field exhibited the maximum absorption at certain relative densities of the graphite powders. These surface plasmon-like modes were observed in graphite, but were not observed when an E field was applied. Multiparticle systems such as graphite powder were found to have significantly different heating behaviors from a single particle. Microwave heating of metal particles is expected to be affected by the structure and shape of the particles.

  10. The research of ceramic materials for applications in the glass industry including microwave heating techniques

    NASA Astrophysics Data System (ADS)

    Kogut, K.; Kasprzyk, K.; Zboromirska-Wnukiewicz, B.; Ruziewicz, T.

    2016-02-01

    The melting of a glass is a very energy-intensive process. Selection of energy sources, the heating technique and the method of heating recovery are a fundamental issue from the furnace design point of view of and economic effectiveness of the process. In these processes the problem constitutes the lack of the appropriate ceramic materials that would meet the requirements. In this work the standard ceramic materials were examined and verified. The possibilities of application of microwave techniques were evaluated. In addition the requirements regarding the parameters of new ceramic materials applied for microwave technologies were determined.

  11. Interpretation of the lunar microwave brightness temperature spectrum - Feasibility of orbital heat flow mapping

    NASA Technical Reports Server (NTRS)

    Keihm, S. J.

    1984-01-01

    The feasibility of an orbital mapping of heat flow by means of microwave radiometers is examined on the basis of a detailed model of the lunar regolith. The results obtained are discussed in terms of contributions of physical properties and regolith structure to the spectral signature of lunation-averaged brightness temperatures. Even for regions for which remote heat flow detection is not feasible, detailed interpretations of remote measurements in terms of physical properties and regolith structure could be made by means of the model presented. Surface and subsurface scattering effects are considered in evaluating possible wavelength dependencies of the microwave emissivity.

  12. Size limitations for microwave cavity to simulate heating of blanket material in fusion reactor

    SciTech Connect

    Wolf, D.

    1987-01-01

    The power profile in the blanket material of a nuclear fusion reactor can be simulated by using microwaves at 200 MHz. Using these microwaves, ceramic breeder materials can be thermally tested to determine their acceptability as blanket materials without entering a nuclear fusion environment. A resonating cavity design is employed which can achieve uniform cross sectional heating in the plane transverse to the neutron flux. As the sample size increases in height and width, higher order modes, above the dominant mode, are propagated and destroy the approximation to the heating produced in a fusion reactor. The limits at which these modes develop are determined in the paper.

  13. Mechanism for microwave heating of 1-(4‧-cyanophenyl)-4-propylcyclohexane characterized by in situ microwave irradiation NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Tasei, Yugo; Yamakami, Takuya; Kawamura, Izuru; Fujito, Teruaki; Ushida, Kiminori; Sato, Motoyasu; Naito, Akira

    2015-05-01

    Microwave heating is widely used to accelerate organic reactions and enhance the activity of enzymes. However, the detailed molecular mechanism for the effect of microwave on chemical reactions is not yet fully understood. To investigate the effects of microwave heating on organic compounds, we have developed an in situ microwave irradiation NMR spectroscopy. 1H NMR spectra of 1-(4‧-cyanophenyl)-4-propylcyclohexane (PCH3) in the liquid crystalline and isotropic phases were observed under microwave irradiation. When the temperature was regulated at slightly higher than the phase transition temperature (Tc = 45 °C) under a gas flow temperature control system, liquid crystalline phase mostly changed to the isotropic phase. Under microwave irradiation and with the gas flow temperature maintained at 20 °C, which is 25 °C below the Tc, the isotropic phase appeared stationary as an approximately 2% fraction in the liquid crystalline phase. The temperature of the liquid crystalline state was estimated to be 38 °C according to the line width, which is at least 7 °C lower than the Tc. The temperature of this isotropic phase should be higher than 45 °C, which is considered to be a non-equilibrium local heating state induced by microwave irradiation. Microwaves at a power of 195 W were irradiated to the isotropic phase of PCH3 at 50 °C and after 2 min, the temperature reached 220 °C. The temperature of PCH3 under microwave irradiation was estimated by measurement of the chemical shift changes of individual protons in the molecule. These results demonstrate that microwave heating generates very high temperature within a short time using an in situ microwave irradiation NMR spectrometer.

  14. Absorption of intense microwaves and ion acoustic turbulence due to heat transport

    SciTech Connect

    De Groot, J.S.; Liu, J.M.; Matte, J.P.

    1994-02-04

    Measurements and calculations of the inverse bremsstrahlung absorption of intense microwaves are presented. The isotropic component of the electron distribution becomes flat-topped in agreement with detailed Fokker-Planck calculations. The plasma heating is reduced due to the flat-topped distributions in agreement with calculations. The calculations show that the heat flux at high microwave powers is very large, q{sub max} {approx} 0.3 n{sub e}v{sub e}T{sub e}. A new particle model to, calculate the heat transport inhibition due to ion acoustic turbulence in ICF plasmas is also presented. One-dimensional PIC calculations of ion acoustic turbulence excited due to heat transport are presented. The 2-D PIC code is presently being used to perform calculations of heat flux inhibition due to ion acoustic turbulence.

  15. A comparative study of infrared and microwave heating for microbial decontamination of paprika powder

    PubMed Central

    Eliasson, Lovisa; Isaksson, Sven; Lövenklev, Maria; Ahrné, Lilia

    2015-01-01

    There is currently a need in developing new decontamination technologies for spices due to limitations of existing technologies, mainly regarding their effects on spices’ sensory quality. In the search of new decontamination solutions, it is of interest to compare different technologies, to provide the industry with knowledge for taking decisions concerning appropriate decontamination technologies for spices. The present study compares infrared (IR) and microwave decontamination of naturally contaminated paprika powder after adjustment of water activity to 0.88. IR respectively microwave heating was applied to quickly heat up paprika powder to 98°C, after which the paprika sample was transferred to a conventional oven set at 98°C to keep the temperature constant during a holding time up to 20 min. In the present experimental set-up microwave treatment at 98°C for 20 min resulted in a reduction of 4.8 log units of the total number of mesophilic bacteria, while the IR treatment showed a 1 log unit lower reduction for the corresponding temperature and treatment time. Microwave and IR heating created different temperature profiles and moisture distribution within the paprika sample during the heating up part of the process, which is likely to have influenced the decontamination efficiency. The results of this study are used to discuss the difficulties in comparing two thermal technologies on equal conditions due to differences in their heating mechanisms. PMID:26483783

  16. Finite Element Analysis of Three Methods for Microwave Heating of Planetary Surfaces

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin; Kaukler, William

    2012-01-01

    In-Situ Resource Utilization will be Ground Breaking technology for sustained exploration of space. Volatiles are present in planetary regolith, but water by far has the most potential for effective utilization. The presence of water at the lunar poles and Mars opens the possibility of using the hydrogen for propellant on missions beyond Earth orbit. Likewise, the oxygen could be used for in-space propulsion for lunar ascent/descent and for space tugs from low lunar orbit to low Earth orbit. Water is also an effective radiation shielding material as well as a valuable expendable (water and oxygen) required for habitation in space. Because of the strong function of water vapor pressure with temperature, heating regolith effectively liberates water vapor by sublimation. Microwave energy will penetrate soil and heat from within, much more efficiently than heating from the surface with radiant heat. This is especially true under vacuum conditions since the heat transfer rate is very low. The depth of microwave penetration is a strong function of the microwave frequency and to a lesser extent on regolith dielectric properties. New methods for delivery of microwaves into lunar and planetary surfaces is being prototyped with laboratory experiments and modeled with COMSOL MultiPhysics. Recent results are discussed.

  17. Combined chromatographic and mass spectrometric toolbox for fingerprinting migration from PET tray during microwave heating.

    PubMed

    Alin, Jonas; Hakkarainen, Minna

    2013-02-13

    A combined chromatographic and mass spectrometric toolbox was utilized to determine the interactions between poly(ethylene terephthalate) (PET) food packaging and different food simulants during microwave heating. Overall and specific migration was determined by combining weight loss measurements with gas chromatography-mass spectrometry (GC-MS) and electrospray ionization mass spectrometry (ESI-MS). This allowed mapping of low molecular weight migrants in the molecular range up to 2000 g/mol. Microwave heating caused significantly faster migration of cyclic oligomers into ethanol and isooctane as compared to migration during conventional heating at the same temperature. This effect was more significant at lower temperature at which diffusion rates are generally lower. It was also shown that transesterification took place between PET and ethanol during microwave heating, leading to formation of diethyl terephthalate. The detected migrants included cyclic oligomers from dimer to hexamer, in most cases containing extra ethylene glycol units, and oxidized Irgafos 168. ESI-MS combined with CID MS-MS was an excellent tool for structural interpretation of the nonvolatile compounds migrating to the food simulants. The overall migration was below the overall migration limit of 10 mg/dm(2) set by the European commission after 4 h of microwave heating at 100 °C in all studied food simulants. PMID:23343184

  18. Experimental study of temperature distribution in rubber material during microwave heating and vulcanization process

    NASA Astrophysics Data System (ADS)

    Chen, Hai-Long; Li, Tao; Liang, Yun; Sun, Bin; Li, Qing-Ling

    2016-07-01

    Microwave technology has been employed to heat sheet rubber, the optical fiber temperature online monitor and optical fiber temperature sensor have been employed to measure the temperature in sheet rubber. The temperature of sheet rubber increased with increase of heating time during microwave heating process in which the maximum of temperature was <100 °C and microwave vulcanization process in which the maximum of temperature was <150 °C, the curves of temperature-time presented nonlinearity. The rate of temperature rising in central zone of sheet rubber was higher than the rate of temperature rising in marginal zone of sheet rubber, and the final temperature in central zone of sheet rubber was also higher than the final temperature in marginal zone of sheet rubber. In the microwave heating and vulcanization process of sheet rubber, the maximum of rate of temperature rising and the maximum of temperature belong to the central zone of sheet rubber, so the distribution of electric field was uneven in heating chamber, which led to the uneven temperature distribution of sheet rubber. The higher electric field intensity value converges on the central zone of sheet rubber.

  19. A comparative study of infrared and microwave heating for microbial decontamination of paprika powder.

    PubMed

    Eliasson, Lovisa; Isaksson, Sven; Lövenklev, Maria; Ahrné, Lilia

    2015-01-01

    There is currently a need in developing new decontamination technologies for spices due to limitations of existing technologies, mainly regarding their effects on spices' sensory quality. In the search of new decontamination solutions, it is of interest to compare different technologies, to provide the industry with knowledge for taking decisions concerning appropriate decontamination technologies for spices. The present study compares infrared (IR) and microwave decontamination of naturally contaminated paprika powder after adjustment of water activity to 0.88. IR respectively microwave heating was applied to quickly heat up paprika powder to 98°C, after which the paprika sample was transferred to a conventional oven set at 98°C to keep the temperature constant during a holding time up to 20 min. In the present experimental set-up microwave treatment at 98°C for 20 min resulted in a reduction of 4.8 log units of the total number of mesophilic bacteria, while the IR treatment showed a 1 log unit lower reduction for the corresponding temperature and treatment time. Microwave and IR heating created different temperature profiles and moisture distribution within the paprika sample during the heating up part of the process, which is likely to have influenced the decontamination efficiency. The results of this study are used to discuss the difficulties in comparing two thermal technologies on equal conditions due to differences in their heating mechanisms. PMID:26483783

  20. Microwave heated resin injector for advanced composite production.

    PubMed

    Stanculovic, Sebastijan; Feher, Lambert

    2008-01-01

    A novel microwave (MW) injector at 2.45 GHz for resin infiltration has been developed at the Institute for Pulsed Power and Microwave Technology (IHM), Research Center Karlsruhe (FZK), Germany. Resin injection is an essential step in the production of carbon fibre reinforced plastics (CFRP) for aerospace applications. A compact, low-cost and automated MW injector provides an efficient and safe energy transfer from the MW source to the resin and supports an appropriate electromagnetic field structure for homogeneous infiltration. The system provides temperature monitoring and an automatized MW power switching, which ensures a fast response of the MW system to rapid changes in the temperature for high flow rates of the resin. In low power measurements with a vector network analyzer, the geometry of the injector cavity has been adjusted to provide an efficient system. The MW injector has been tested for specific resin systems infiltrations. PMID:19227063

  1. Microwave heating power distribution in electron-cyclotron resonance processing plasmas, experiment and theory

    SciTech Connect

    Douglass, S.R.; Eddy, C. Jr.; Lampe, M.; Joyce, G.; Slinker, S.; Weber, B.V.

    1995-12-31

    The authors are currently investigating the mechanisms of microwave power absorption in an ECR plasma. The microwave electric field is detected with an antenna at the end of a shielded co-ax cable, connected to a bolometer for power measurements. Initial measurements have been 1-D along the axis of the plasma chamber. Later, 3-D profiles will be made of the microwave heating power distribution. A comparison of the experimental results with the theoretical microwave absorption are presented. A ray tracing analysis of the propagating right hand wave are given, including both collisional and collisionless absorption. Mode conversion effects are studied to explain why most of the power is absorbed at the entry window, especially the L wave power.

  2. Effects of relative density on microwave heating of various carbon powder compacts microwave-metallic multi-particle coupling using spatially separated magnetic fields

    NASA Astrophysics Data System (ADS)

    Kashimura, K.; Hasegawa, N.; Suzuki, S.; Hayashi, M.; Mitani, T.; Shinohara, N.; Nagata, K.

    2013-01-01

    We have investigated the microwave heating characteristics of non-magnetic conductive multi-particle systems using spatially separated electric and magnetic fields (Emax and Hmax, respectively) to determine the effects of the multi-particle structure on microwave heating. Pure carbon, carbon black, and artificial graphite multi-particle systems exhibited peak microwave absorption at specific relative densities only under Hmax. These absorptions can be categorized into two types: one originates from coupling between metal spheres, while the other originates from a heterogeneous distribution of particles.

  3. Heat transfer enhanced microwave process for stabilization of liquid radioactive waste slurry. Final report

    SciTech Connect

    White, T.L.

    1995-03-31

    The objectve of this CRADA is to combine a polymer process for encapsulation of liquid radioactive waste slurry developed by Monolith Technology, Inc. (MTI), with an in-drum microwave process for drying radioactive wastes developed by Oak Ridge National Laboratory (ORNL), for the purpose of achieving a fast, cost-effectve commercial process for solidification of liquid radioactive waste slurry. Tests performed so far show a four-fold increase in process throughput due to the direct microwave heating of the polymer/slurry mixture, compared to conventional edge-heating of the mixer. We measured a steady-state throughput of 33 ml/min for 1.4 kW of absorbed microwave power. The final waste form is a solid monolith with no free liquids and no free particulates.

  4. Calculation of temperatures in microwave-heated two-dimensional ceramic bodies

    SciTech Connect

    Evans, J.W. . Dept. of Materials Science and Mineral Engineering Lawrence Berkeley Lab., CA )

    1993-08-01

    Temperatures are calculated in a ceramic material exposed to microwaves. The method entails calculation of electromagnetic fields by integral formulation and subsequent solution of the heat conduction equation for temperatures in a ceramic piece. The solution of the equations is numerical and the parameters used are estimates for properties of SiC. The results include a case where the complex dielectric constant is varied with temperature. The computed results demonstrate that SiC can be heated to high temperatures (1,000-1,500 K) and that both the temperature and the temperature gradient can be controlled by varying the power density of the microwaves and the external cooling. The results also exhibit high sensitivity of temperatures to the dimensions of the material and the orientation in which microwaves impinge on the ceramic body.

  5. Microwave Heating as an Alternative Quarantine Method for Disinfestation of Stored Food Grains

    PubMed Central

    Kumar, Girish; Shah, Narendra G.

    2013-01-01

    Insects and pests constitute a major threat to food supplies all over the world. Some estimates put the loss of food grains because of infestation to about 40% of the world production. Contemporary disinfestation methods are chemical fumigation, ionizing radiation, controlled atmosphere, conventional hot air treatment, and dielectric heating, that is, radio frequency and microwave energy, and so forth. Though chemical fumigation is being used extensively in stored food grains, regulatory issues, insect resistance, and environmental concerns demand technically effective and environmentally sound quarantine methods. Recent studies have indicated that microwave treatment is a potential means of replacing other techniques because of selective heating, pollution free environment, equivalent or better quality retention, energy minimization, and so forth. The current paper reviews the recent advances in Microwave (MW) disinfestation of stored food products and its principle and experimental results from previous studies in order to establish the usefulness of this technology. PMID:26904615

  6. Microwave emission spectrum of the moon: mean global heat flow and average depth of the regolith.

    PubMed

    Keihm, S J; Langseth, M G

    1975-01-10

    Earth-based observations of the lunar microwave brightness temperature spectrum at wavelengths between 5 and 500 centimeters, when reexamined in the light of physical property data derived from the Apollo program, tentatively support the high heat flows measured in situ and indicate that a regolith thickness between 10 and 30 meters may characterize a large portion of the lunar near side. PMID:17844211

  7. Tolazoline decreases survival time during microwave-induced lethal heat stress in anesthetized rats

    SciTech Connect

    Jauchem, J.R.; Chang, K.S.; Frei, M.R.

    1996-03-01

    Effects of {alpha}-adrenergic antagonists have been studied during environmental heating but not during microwave-induced heating. Tolazoline may exert some of its effects via {alpha}-adrenergic blockade. In the present study, ketamine-anesthetized Sprague-Dawley rats were exposed to 2450-MHz microwaves at an average power density of 60 mW/cm{sup 2} (whole-body specific absorption rate of approximately 14 W/kg) until lethal temperatures were attained. The effects of tolazoline (10 mg/kg body weight) on physiological responses (including changes in body temperature, heart rate, blood pressure, and respiratory rate) were examined. Survival time was significantly shorter in the tolazoline group than in saline-treated animals. In general, heart rate and blood pressure responses were similar to those that occur during environmental heat stress. Heart rate, however, was significantly elevated in animals that received tolazoline, both before and during terminal microwave exposure. It is possible that changes associated with the elevated heart rate (e.g., less cardiac filling) in tolazoline-treated animals resulted in greater susceptibility to microwave-induced heating and the lower survival time. 47 refs., 3 figs., 2 tabs.

  8. Microwave emission spectrum of the moon - Mean global heat flow and average depth of the regolith

    NASA Technical Reports Server (NTRS)

    Keihm, S. J.; Langseth, M. G.

    1975-01-01

    Earth-based observations of the lunar microwave brightness temperature spectrum at wavelengths between 5 and 500 centimeters, when reexamined in the light of physical property data derived from the Apollo program, tentatively support the high heat flows measured in situ and indicate that a regolith thickness between 10 and 30 meters may characterize a large portion of the lunar near side.

  9. Sustainable synthesis of chemical entities by microwave heating with nano-catalysis in water

    EPA Science Inventory

    •Sustainable synthesis of chemical entities by microwave heating with nano-catalysis in water •CRADA’s with the private companies, CEM corporation and VeruTEK Technologies •Green Chemistry principles are accommodated via multi-faceted approach. Learning from nature- using na...

  10. Microwave-based laboratory experiments for internally-heated mantle convection

    SciTech Connect

    Limare, A.; Di Giuseppe, E.; Vilella, K.; Farnetani, C. G.; Kaminski, E.; Jaupart, C.; Surducan, E.; Surducan, V.; Neamtu, C.

    2013-11-13

    The thermal evolution of terrestrial planets is mainly controlled by the amount of radioactive heat sources in their mantle, and by the geometry and efficiency of solid state thermo-chemical convection within. So far, these systems have been studied using numerical methods only and cross validation by laboratory analogous experiments has not been conducted yet. To fill this gap we perform the first laboratory experiments of mantle convection driven by microwave-generated internal heating. We use a 30×30×5 cm{sup 3} experimental tank filled with 0.5 % Natrosol in water mixture (viscosity 0.6 Pa.s at 20°C). The fluid is heated from within by a microwave device that delivers a uniform volumetric heating from 10 to 70 kW/m{sup 3}; the upper boundary of the fluid is kept at constant temperature, whereas the lower boundary is adiabatic. The velocity field is determined with particle image velocimetry and the temperature field is measured using thermochromic liquid crystals which enable us to charaterize the geometry of the convective regime as well as its bulk thermal evolution. Numerical simulations, conducted using Stag-3D in 3D cartesian geometry, reproduce the experimental setup (i.e., boundary conditions, box aspect ratio, temperature dependence of physical parameters, internal heating rate). The successful comparison between the experimental and numerical results validates our approach of modelling internal heating using microwaves.

  11. Rapid synthesis of [18F]-fluoroestradiol: remarkable advantage of microwaving over conventional heating

    PubMed Central

    Shi, Jianfeng; Afari, George; Bhattacharyya, Sibaprasad

    2014-01-01

    16α-[18F]-fluoroestradiol ([18F]FES) is known as a clinically important tracer in nuclear medicine as an estrogen receptor (ER) ligand for investigating primary and metastatic breast cancers. Synthesizing [18F]FES is a two-step process associated with [18F]fluoride incorporation to the precursor (3-methoxymethyl 16β, 17β-epiestriol-O-cyclic sulfone, MMSE) and subsequent hydrolysis of the [18F]fluorinated intermediate with 2N HCl. The impact of microwave heating (MW) on both fluorination and hydrolysis reactions was investigated. The duration and temperatures of the fluorination reaction were varied for both MW and conventional heating (CH) methods. Chemical and radiochemical purities and radiochemical yields were investigated for CH and compared to microwave-assisted radiosyntheses. Quality control tests of microwave-assisted [18F]FES were performed following United States Pharmacopeia (USP) procedures for clinical-grade positron emission tomography (PET) pharmaceuticals. The results demonstrate that microwaving not only improves the 18F-fluoride incorporation (~ 55% improvement at 110 °C for 4 min) but also significantly reduces hydrolysis time (~ 7-fold reduction at 120 °C) in compare to CH under similar conditions. The overall isolated radiochemical yield of purified [18F]FES was significantly higher (~ 90% improvement) with MW, and side-products were notably fewer. Quality control test results demonstrated that [18F]FES produced by microwaving was suitable for human injection. PMID:25476421

  12. Combining Satellite Microwave Radiometer and Radar Observations to Estimate Atmospheric Latent Heating Profiles

    NASA Technical Reports Server (NTRS)

    Grecu, Mircea; Olson, William S.; Shie, Chung-Lin; L'Ecuyer, Tristan S.; Tao, Wei-Kuo

    2009-01-01

    In this study, satellite passive microwave sensor observations from the TRMM Microwave Imager (TMI) are utilized to make estimates of latent + eddy sensible heating rates (Q1-QR) in regions of precipitation. The TMI heating algorithm (TRAIN) is calibrated, or "trained" using relatively accurate estimates of heating based upon spaceborne Precipitation Radar (PR) observations collocated with the TMI observations over a one-month period. The heating estimation technique is based upon a previously described Bayesian methodology, but with improvements in supporting cloud-resolving model simulations, an adjustment of precipitation echo tops to compensate for model biases, and a separate scaling of convective and stratiform heating components that leads to an approximate balance between estimated vertically-integrated condensation and surface precipitation. Estimates of Q1-QR from TMI compare favorably with the PR training estimates and show only modest sensitivity to the cloud-resolving model simulations of heating used to construct the training data. Moreover, the net condensation in the corresponding annual mean satellite latent heating profile is within a few percent of the annual mean surface precipitation rate over the tropical and subtropical oceans where the algorithm is applied. Comparisons of Q1 produced by combining TMI Q1-QR with independently derived estimates of QR show reasonable agreement with rawinsonde-based analyses of Q1 from two field campaigns, although the satellite estimates exhibit heating profile structure with sharper and more intense heating peaks than the rawinsonde estimates. 2

  13. Microwave heating: Industrial applications. September 1986-September 1989 (Citations from the COMPENDEX data base). Report for September 1986-September 1989

    SciTech Connect

    Not Available

    1989-10-01

    This bibliography contains citations concerning industrial uses and design of microwave heating equipment. Included are heating and drying of paper, industrial process heat, vulcanization, textile processing, metallurgical heat for sintering and ceramic manufacturing, food processing, and curing of polymers. (This updated bibliography contains 116 citations, 11 of which are new entries to the previous edition.)

  14. Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

    DOEpatents

    Meek, T.T.; Blake, R.D.

    1985-04-03

    A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

  15. Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

    DOEpatents

    Meek, T.T.; Blake, R.D.

    1987-09-22

    A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate. 2 figs.

  16. Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

    DOEpatents

    Meek, Thomas T.; Blake, Rodger D.

    1987-01-01

    A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

  17. Microwave field distribution and electron cyclotron resonance heating process

    SciTech Connect

    Consoli, F.; Celona, L.; Ciavola, G.; Gammino, S.; Maimone, F.; Barbarino, S.; Catalano, R. S.; Mascali, D.

    2008-02-15

    In an electron cyclotron resonance ion source, ions are produced from a plasma generated and sustained by microwaves with a proper frequency. Some experiments showed that the plasma formation, the consequent amount of particles extracted from the source, and the related beam shape strongly depend on the frequency of the electromagnetic wave feeding the cavity. In order to have a better understanding of these phenomena, in this work we deal with the description of the motion of a charged particle inside the plasma chamber model of the SERSE ion source operating at INFN-LNS in Catania, the analysis being applicable to any similar apparatus. The electromagnetic fields inside the vacuum filled chamber were determined theoretically and, together with proper simulations, their fundamental role on the particle motion, on their confinement, and on the energy transfer they are subjected to during their motion within the cavity is shown.

  18. Evaluation of microwave oven heating for prediction of drug-excipient compatibilities and accelerated stability studies.

    PubMed

    Schou-Pedersen, Anne Marie V; Østergaard, Jesper; Cornett, Claus; Hansen, Steen Honoré

    2015-05-15

    Microwave ovens have been used extensively in organic synthesis in order to accelerate reaction rates. Here, a set up comprising a microwave oven combined with silicon carbide (SiC) plates for the controlled microwave heating of model formulations has been applied in order to investigate, if a microwave oven is applicable for accelerated drug stability testing. Chemical interactions were investigated in three selected model formulations of drug and excipients regarding the formation of ester and amide reaction products. In the accelerated stability studies, a design of experiments (DoE) approach was applied in order to be able to rank excipients regarding reactivity: Study A: cetirizine with PEG 400, sorbitol, glycerol and propylene glycol. Study B: 6-aminocaproic acid with citrate, acetate, tartrate and gluconate. Study C: atenolol with citric, tartaric, malic, glutaric, and sorbic acid. The model formulations were representative for oral solutions (co-solvents), parenteral solutions (buffer species) and solid dosage forms (organic acids applicable for solubility enhancement). The DoE studies showed overall that the same impurities were generated by microwave oven heating leading to temperatures between 150°C and 180°C as compared to accelerated stability studies performed at 40°C and 80°C using a conventional oven. Ranking of the reactivity of the excipients could be made in the DoE studies performed at 150-180°C, which was representative for the ranking obtained after storage at 40°C and 80°C. It was possible to reduce the time needed for drug-excipient compatibility testing of the three model formulations from weeks to less than an hour in the three case studies. The microwave oven is therefore considered to be an interesting alternative to conventional thermal techniques for the investigation of drug-excipient interactions during preformulation. PMID:25746946

  19. Microwave furnace having microwave compatible dilatometer

    DOEpatents

    Kimrey, Jr., Harold D.; Janney, Mark A.; Ferber, Mattison K.

    1992-01-01

    An apparatus for measuring and monitoring a change in the dimension of a sample being heated by microwave energy is described. The apparatus comprises a microwave heating device for heating a sample by microwave energy, a microwave compatible dilatometer for measuring and monitoring a change in the dimension of the sample being heated by microwave energy without leaking microwaves out of the microwave heating device, and a temperature determination device for measuring and monitoring the temperature of the sample being heated by microwave energy.

  20. Microwave furnace having microwave compatible dilatometer

    DOEpatents

    Kimrey, H.D. Jr.; Janney, M.A.; Ferber, M.K.

    1992-03-24

    An apparatus for measuring and monitoring a change in the dimension of a sample being heated by microwave energy is described. The apparatus comprises a microwave heating device for heating a sample by microwave energy, a microwave compatible dilatometer for measuring and monitoring a change in the dimension of the sample being heated by microwave energy without leaking microwaves out of the microwave heating device, and a temperature determination device for measuring and monitoring the temperature of the sample being heated by microwave energy. 2 figs.

  1. Catalytic pyrolysis of sugarcane bagasse by using microwave heating.

    PubMed

    Kuan, Wen-Hui; Huang, Yu-Fong; Chang, Chi-Cheng; Lo, Shang-Lien

    2013-10-01

    The aim of this study was to research the catalytic effects on the microwave pyrolysis of sugarcane bagasse and thus to discuss the reaction performance, product distribution, and kinetic analysis. With the addition of metal-oxides served as catalysts, reaction results such as mass reduction ratio and reaction rate increased, even the maximum temperature decreased. Adding either NiO or CaO slightly increased the production of H2, while adding either CuO or MgO slightly decreased it. The addition of either CaO or MgO enhanced the gaseous production, and either NiO or CuO addition enhanced the liquid production. There could be several secondary reactions such as self-gasification and interactions among the gases originally produced during the pyrolysis stage to alter the composition of gaseous product and the final three-phase product distribution. The catalyst addition slightly increased the activation energy but greatly increased the pre-exponential factor. PMID:23948270

  2. Evaluation of high-temperature and short-time sterilization of injection ampules by microwave heating.

    PubMed

    Sasaki, K; Honda, W; Miyake, Y

    1998-01-01

    The high-temperature and short-time sterilization by microwave heating with a continuous microwave sterilizer (MWS) was evaluated. The evaluation were performed with respect to: [1] lethal effect against microorganisms corresponding to F-value, and [2] reliability of MWS sterilization process. Bacillus stearothermophilus ATCC 7953 spores were used as the biological indicator and the heat-resistance of spores was evaluated with conventional heating method (121-129 degrees C). In MWS sterilization (125-135 degrees C), the actual lethal effect against B. stearothermophilus spores was almost in agreement with the F-value and the survival curve against the F-value was quite consistent with that for the autoclave. These results suggest that the actual lethal effect could be estimated by the F-value with heat-resistance parameters of spores from lower than actual temperatures and that there was no nonthermal effect of the microwave on B. stearothermophilus spores. The reliability of sterilization with the MWS was confirmed using more than 25,000 test ampules containing biological indicators. All biological indicators were killed, thus the present study shows that the MWS was completely reliable for all ampules. PMID:9542408

  3. An experimental study of waveguide coupled microwave heating with conventional multicusp negative ion sources

    SciTech Connect

    Komppula, J.; Kalvas, T.; Koivisto, H.; Laulainen, J.; Tarvainen, O.

    2015-04-08

    Negative ion production with conventional multicusp plasma chambers utilizing 2.45 GHz microwave heating is demonstrated. The experimental results were obtained with the multicusp plasma chambers and extraction systems of the RF-driven RADIS ion source and the filament driven arc discharge ion source LIISA. A waveguide microwave coupling system, which is almost similar to the one used with the SILHI ion source, was used. The results demonstrate that at least one third of negative ion beam obtained with inductive RF-coupling (RADIS) or arc discharge (LIISA) can be achieved with 1 kW of 2.45 GHz microwave power in CW mode without any modification of the plasma chamber. The co-extracted electron to H{sup −} ratio and the optimum pressure range were observed to be similar for both heating methods. The behaviour of the plasma implies that the energy transfer from the microwaves to the plasma electrons is mainly an off-resonance process.

  4. Scale-up of the nitridation and sintering of silicon preforms using microwave heating

    SciTech Connect

    Kiggans, J.O. Jr.; Tiegs, T.N.; Davisson, C.C.; Morrow, M.S.; Garvey, G.J.

    1996-05-01

    Scale-up studies were performed in which microwave heating was used to fabricate reaction-bonded silicon nitride and sintered reaction-bonded silicon nitride (SRBSN). Tests were performed in both a 2.45 GHz, 500 liter and a 2.45 GHz, 4,000 liter multimode cavities. A variety of sizes, shapes, and compositions of silicon preforms were processed in the studies, including bucket tappets and clevis pins for diesel engines. Up to 230 samples were processed in a single microwave furnace run. Data were collected which included weight gains for nitridation experiments, and final densities for nitridation and sintering experiments. For comparison, nitridation and sintering studies were performed using a conventional resistance-heated furnace.

  5. Deposition of Hard Chrome Coating onto Heat Susceptible Substrates by Low Power Microwave Plasma Spray

    NASA Astrophysics Data System (ADS)

    Redza, Ahmad; Yasui, Toshiaki; Fukumoto, Masahiro

    2016-02-01

    Microwave plasma spray requires relatively low power, which is lower than 1 kW in comparison to other plasma spraying method. Until now, we are able to deposit Cu and Hydroxyapatite coating onto heat susceptible substrate, CFRP which are difficult for conventional plasma spray due to the excessive heat input. In this paper, a hard chromium coating was deposited onto SUS304 and CFRP by a low power microwave plasma spray technique. By controlling the working gas flow rate and spraying distance, a hard chrome coating with thickness of approximately 30 μm was successfully deposited onto CFRP substrate with hardness of 1110 Hv0.05. Furthermore, the coating produced here is higher than that produced by hard chrome plating.

  6. Application of microwave radiation to biofilm heating during wastewater treatment in trickling filters.

    PubMed

    Zieliński, Marcin; Zielińska, Magdalena; Dębowski, Marcin

    2013-01-01

    The purpose of this study was to demonstrate the potential for improving wastewater treatment by the application of microwave radiation (MW) compared to convective heating (CH) of trickling filters. Microwaves were delivered to the biofilm in a continuous and intermittent way to obtain temperatures of 20, 25, 35 and 40 °C. Although there was no effect of MW on organic removal, the observed yield coefficient was lower during the continuous MW supply compared to the periodic dosage and CH. The presence of organic compounds in the influent and continuous biofilm exposure to MW resulted in ca. 10% higher efficiency and ca. 20% higher rate of nitrification compared to intermittent MW dosage and CH. Independent of the method of reactor heating, the absence of organic carbon in the influent induced a significant increase in ammonium oxidation efficiency at 20-35 °C. Despite the aerobic conditions in trickling filters, nitrogen loss was observed. PMID:23131645

  7. Dielectric properties of cereals at frequencies useful for processes with microwave heating.

    PubMed

    Torrealba-Meléndez, Richard; Sosa-Morales, María Elena; Olvera-Cervantes, José Luis; Corona-Chávez, Alonso

    2015-12-01

    Dielectric properties of barley, corn (white and yellow), sorghum, and wheat at microwave frequencies for heating purpose were analyzed. Properties were determined at 915, 2450 and 5800 MHz with the free space transmission method in the cereals at 20, 30, 40, 50 and 60 °C. ε´ and ε"of all the cereals decreased with increasing frequency. ε´ slightly increased with temperature, while ε "remained practically constant for all the cereals in the temperature range from 20 to 60 °C. Penetration depth decreased with increasing frequency for all the samples, and increased with increasing temperature at 915 MHz, except for barley. These results are useful for further microwave heating applications for the studies on cereals. PMID:26604422

  8. Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

    PubMed

    Soto-Reyes, Nohemí; Temis-Pérez, Ana L; López-Malo, Aurelio; Rojas-Laguna, Roberto; Sosa-Morales, María Elena

    2015-05-01

    Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes. PMID:25827444

  9. Characterization of bulk stainless steel joints developed through microwave hybrid heating

    SciTech Connect

    Bansal, Amit; Sharma, Apurbba Kumar; Kumar, Pradeep; Das, Shantanu

    2014-05-01

    Processing of metallic materials through microwave heating is a challenging area of research. In the present work, joining of stainless steel-316 to stainless steel-316 in the bulk form has been carried out by placing stainless steel-316 powder at the interface and through targeted heating using microwave hybrid heating. The trials were carried out in a multimode microwave applicator at a frequency of 2.45 GHz and power 900 W. The developed joints were characterized using X-ray diffraction, field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscope and measurement of Vicker's microhardness, porosity and tensile strength. The X-ray diffraction spectrum of the developed joint shows the presence of chromium carbide, iron carbide and iron silicide phases that eventually contribute to enhancement of the microhardness of the joint. The scanning electron microscope micrographs confirm classical metallurgical bonding between the substrate and the interface (molten powder) layer; the epitaxial growth rate was observed adjacent to the fusion zone. The average observed Vicker's microhardness in the joint zone on the grain boundary was significantly higher than that inside the grains due to the presence of various hard phases at the grain boundaries. Evaluation of the tensile strength of the joints showed an average ultimate tensile strength of 425.0 MPa with an average elongation of 9.44%. - Highlights: • Joining of stainless steel (SS-316) plates using microwave hybrid heating • Epitaxial growth rate observed adjacent to the fusion zone of welded joint • The ultimate tensile strength of the order of 425.0 MPa with 9.44% elongation.

  10. Optimizing electro-thermo Helds for soot oxidation using microwave heating and metal

    NASA Astrophysics Data System (ADS)

    Al-Wakeel, Haitham B.; Karim, Z. A. Abdul; Al-Kayiem, Hussain H.

    2015-04-01

    Soot is produced by incomplete combustion of various carbon-containing compounds. Soot is one of the main environmental pollutants and has become an important environmental and specific objective. To reduce soot from exhaust emission of diesel engine, a new technique is proposed and implemented by using metal inserted in the soot exposed to electromagnetic radiation. This paper presents a simulation to obtain optimum metal length and shape that give optimum electric field for attaining temperature enough for soot oxidation using microwave heating and a thin metal rod. Four cases were numerically examined to investigate the electric field and temperature distributions in a mono-mode TE10 microwave cavity having closed surfaces of perfect electric conductors. The operating frequency is 2.45 GHz, and power supply is 1500 W. The simulation methodology is coupling the absorbed electromagnetic energy with heat transfer energy. The absorbed electromagnetic energy is found from the electric field within the soot. The simulation was run using ANSYS based on finite element method. The results of the four simulation cases show that the optimum simulation is represented by case 2 where the value of electric field is 39000 V/m and heating time to arrive at the oxidation temperature (873 K) is 35 s using cylindrical metal rod of 8 mm length. It is revealed that the concept of achieving high temperature for soot oxidation by using thin metal rod inside a microwave cavity can be applied.

  11. Surface modification of plasmonic nanostructured materials with thiolated oligonucleotides in 10 seconds using selective microwave heating.

    PubMed

    Abel, Biebele; Aslan, Kadir

    2012-11-01

    This study demonstrates the proof-of-principle of rapid surface modification of plasmonic nanostructured materials with oligonucleotides using low power microwave heating. Due to their interesting optical and electronic properties, silver nanoparticle films (SNFs, 2 nm thick) deposited onto glass slides were used as the model plasmonic nanostructured materials. Rapid surface modification of SNFs with oligonucleotides was carried out using two strategies (1) Strategy 1: for ss-oligonucleotides, surface hybridization and (2) Strategy 2: for ds-oligonucleotides, solution hybridization), where the samples were exposed to 10, 15, 30 and 60 seconds microwave heating. To assess the efficacy of our new rapid surface modification technique, identical experiments carried out without the microwave heating (i.e., conventional method), which requires 24 hours for the completion of the identical steps. It was found that SNFs can be modified with ss- and ds-oligonucleotides in 10 seconds, which typically requires several hours of incubation time for the chemisorption of thiol groups on to the planar metal surface using conventional techniques. PMID:23645933

  12. Superficial heat reduction technique for a hybrid microwave-optical device.

    PubMed

    Al-Armaghany, A; Tong, K; Leung, T S

    2013-01-01

    Microwave applicator in the form of a circularly polarized microstrip patch antenna is proposed to provide localized deep heating in biological tissue, which causes blood vessels to dilate leading to changes in tissue oxygenation. These changes are monitored by an integrated optical system for studying thermoregulation in different parts of the human body. Using computer simulations, this paper compares circularly and linearly polarized antennas in terms of the efficiency of depositing electromagnetic (EM) energy and the heating patterns. The biological model composes of the skin, fat and muscle layers with appropriate dielectric and thermal properties. The results show that for the same specific absorption rate (SAR) in the muscle, the circularly polarized antenna results in a lower SAR in the skin-fat interface than the linearly polarized antenna. The thermal distribution is also presented based on the biological heat equation. The proposed circularly polarized antenna shows heat reduction in the superficial layers in comparison to the linearly polarized antenna. PMID:24110546

  13. Rapid PCR amplification using a microfluidic device with integrated microwave heating and air impingement cooling.

    PubMed

    Shaw, Kirsty J; Docker, Peter T; Yelland, John V; Dyer, Charlotte E; Greenman, John; Greenway, Gillian M; Haswell, Stephen J

    2010-07-01

    A microwave heating system is described for performing polymerase chain reaction (PCR) in a microfluidic device. The heating system, in combination with air impingement cooling, provided rapid thermal cycling with heating and cooling rates of up to 65 degrees C s(-1) and minimal over- or under-shoot (+/-0.1 degrees C) when reaching target temperatures. In addition, once the required temperature was reached it could be maintained with an accuracy of +/-0.1 degrees C. To demonstrate the functionality of the system, PCR was successfully performed for the amplification of the Amelogenin locus using heating rates and quantities an order of magnitude faster and smaller than current commercial instruments. PMID:20414500

  14. Development of a compact cylindrical reaction cavity for a microwave dielectric heating system.

    PubMed

    Kim, Myungsik; Kim, Kwangsoo

    2012-03-01

    This paper describes a compact reaction cavity for a microwave-assisted synthesis system. The microwave dielectric heating is a key technology to improve synthesizing yield, however, the large size of the microwave generation and reaction parts in an all-in-one system is a major obstacle when applying the technique to various systems, of which the installation space is limited. For this particular problem, a compact stand-alone cylindrical reaction cavity was developed in the current study. A microwave excited from a monopole probe, which is inserted into the side of the cavity, is transferred to a reaction mixture through the upper hole of the cavity. The cavity is miniaturized by filling it with an alumina ceramic dielectric. Fine-tuning of the resonance frequency becomes available by controlling the length of the inserted screw between the probe and the upper hole. The physical properties of the cavity were simulated using high frequency structural simulator (HFSS) and the produced cavity was tested using an Agilent E8357A network analyzer. The test results show that the developed cavity is able to send enough energy to various solvents. PMID:22462944

  15. Rapid Online Non-Enzymatic Protein Digestion Combining Microwave Heating Acid Hydrolysis and Electrochemical Oxidation

    PubMed Central

    Basile, Franco; Hauser, Nicolas

    2010-01-01

    We report an online non-enzymatic method for site-specific digestion of proteins to yield peptides that are well suited for collision induced dissociation (CID) tandem mass spectrometry (MS/MS). The method combines online microwave heating acid hydrolysis at aspartic acid and online electrochemical oxidation at tryptophan and tyrosine. The combined microwave/electrochemical (microwave/echem) digestion is reproducible and produces peptides with an average sequence length of 10 amino acids. This peptide length is similar to the average peptide length of 9 amino acids obtained by digestion of proteins with the enzyme trypsin. As a result, the peptides produced by this novel non-enzymatic digestion method, when analyzed by ESI-MS, produce protonated molecules with mostly +1 and +2 charge states. The combination of these two non-enzymatic methods overcomes shortcomings with each individual method in that: i) peptides generated by the microwave-hydrolysis method have an average amino acid length of 16 amino acids, and ii) the inability of the electrochemical-cleavage method to reproducibly digest proteins with molecular masses above 4 kDa. Preliminary results are presented on the application and utility of this rapid online digestion (total of 6 min digestion time) on a series of standard peptides and proteins as well as an E. coli protein extract. PMID:21138252

  16. Theoretical analysis of the microwave-drill near-field localized heating effect

    NASA Astrophysics Data System (ADS)

    Jerby, E.; Aktushev, O.; Dikhtyar, V.

    2005-02-01

    The microwave-drill principle [Jerby et al., Science 298, 587 (2002)] is based on a localized hot-spot effect induced by a near-field coaxial applicator. The microwave drill melts the nonmetallic material locally and penetrates mechanically into it to shape the hole. This paper presents a theoretical analysis of the thermal-runaway effect induced in front of the microwave drill. The model couples the Maxwell's and heat equations including the material's temperature-dependent properties. A finite-difference time-domain algorithm is applied in a two-time-scale numerical model. The simulation is demonstrated for mullite, and benchmarked in simplified cases. The results show a temperature rise of ˜103K/s up to 1300K within a hot spot confined to a ˜4-mm width (˜0.1 wavelength). The input-port response to this near-field effect is modeled by equivalent time-varying lumped-circuit elements. Besides the physical insight, this theoretical study provides computational tools for design and analysis of microwave drills and for their real-time monitoring and adaptive impedance matching.

  17. Mantle Convection in a Microwave Oven: New Perspectives for the Internally Heated Convection

    NASA Astrophysics Data System (ADS)

    Limare, A.; Fourel, L.; Surducan, E.; Neamtu, C.; Surducan, V.; Vilella, K.; Farnetani, C. G.; Kaminski, E. C.; Jaupart, C. P.

    2015-12-01

    The thermal evolution of silicate planets is primarily controlled by the balance between internal heating - due to radioactive decay - and heat transport by mantle convection. In the Earth, the problem is particularly complex due to the heterogeneous distribution of heat sources in the mantle and the non-linear coupling between this distribution and convective mixing. To investigate the behaviour of such systems, we have developed a new technology based on microwave absorption to study internally-heated convection in the laboratory. This prototype offers the ability to reach the high Rayleigh-Roberts and Prandtl numbers that are relevant for planetary convection. Our experimental results obtained for a uniform distribution of heat sources were compared to numerical calculations reproducing exactly experimental conditions (3D Cartesian geometry and temperature-dependent physical properties), thereby providing the first cross validation of experimental and numerical studies of convection in internally-heated systems. We find that the thermal boundary layer thickness and interior temperature scale with RaH-1/4, where RaH is the Rayleigh-Roberts number, as theoretically predicted by scaling arguments on the dissipation of kinetic energy. Our microwave-based method offers new perspectives for the study of internally-heated convection in heterogeneous systems which have been out of experimental reach until now. We are able to selectively heat specific regions in the convecting layer, through the careful control of the absorption properties of different miscible fluids. This is analogous to convection in the presence of chemical reservoirs with different concentration of long-lived radioactive isotopes. We shall show results for two different cases: the stability of continental lithosphere over a convective fluid and the evolution of a hidden enriched reservoir in the lowermost mantle.

  18. Temperature measurements with two different IR sensors in a continuous-flow microwave heated system.

    PubMed

    Rydfjord, Jonas; Svensson, Fredrik; Fagrell, Magnus; Sävmarker, Jonas; Thulin, Måns; Larhed, Mats

    2013-01-01

    In a continuous-flow system equipped with a nonresonant microwave applicator we have investigated how to best assess the actual temperature of microwave heated organic solvents with different characteristics. This is non-trivial as the electromagnetic field will influence most traditional methods of temperature measurement. Thus, we used a microwave transparent fiber optic probe, capable of measuring the temperature inside the reactor, and investigated two different IR sensors as non-contact alternatives to the internal probe. IR sensor 1 measures the temperature on the outside of the reactor whilst IR sensor 2 is designed to measure the temperature of the fluid through the borosilicate glass that constitutes the reactor wall. We have also, in addition to the characterization of the before mentioned IR sensors, developed statistical models to correlate the IR sensor reading to a correct value of the inner temperature (as determined by the internal fiber optic probe), thereby providing a non-contact, indirect, temperature assessment of the heated solvent. The accuracy achieved with these models lie well within the range desired for most synthetic chemistry applications. PMID:24204419

  19. Potential risk of bisphenol A migration from polycarbonate containers after heating, boiling, and microwaving.

    PubMed

    Lim, Duck Soo; Kwack, Seung Jun; Kim, Kyu-Bong; Kim, Hyung Sik; Lee, Byung Mu

    2009-01-01

    The migration levels of bisphenol A (BPA) were analyzed in food samples by high-performance liquid chromatography (HPLC) from polycarbonate (PC) bottles subjected to simulated use by heating with microwave, heating in a boiling water bath, or filling them with boiling hot water (100 degrees C). Migration testing performed in PC bottles filled with steamed rice or hot cooked pork, standing at room temperature, or heated in a boiling water bath (100 degrees C) showed that BPA was not detected at the limit of detection (LOD) of 1 microg/L (ppb). In contrast, heating by microwaving to 100 degrees C for 9 min increased BPA migration levels from 6 to 18 ppb and from 5 to 15 ppb for steamed rice or for cooked pork, respectively. In addition, 3 different PC bottles were tested by filling them with boiling hot water (100 degrees C) and leaving them to stand at room temperature for up to 3 h. The mean BPA levels from the bottles increased in a time-dependent manner, with the range of not detected (ND) to 2.5 ppb after 60 min. However, none of the PC bottles released BPA at levels that exceed the recently established specific migration limits (SML) of 600 ppb established by European Union and Korea Food and Drug Administration (KFDA). Data suggest that the use of PC plastic bottles in our daily life is considered safe in Korea. PMID:20077198

  20. The microwave heating of two-dimensional slabs with small Arrhenius absorptivity

    NASA Astrophysics Data System (ADS)

    Liu, B.; Marchant, T. R.

    1999-04-01

    The microwave heating of two-dimensional slabs in a long rectangular waveguide propagating the TE10 mode is examined. The temperature dependency of the electrical conductivity and the thermal absorptivity is assumed to be governed by the Arrhenius law, while both the electrical permittivity and the magnetic permeability are assumed constant. The governing equations are the forced heat equation and the steady-state version of Maxwell's equation while the boundary conditions take into account both convective and radiative heat loss. Approximate analytical solutions, valid for small thermal absorptivity, are found for the temperature and the electric-field amplitude using the Galerkin method. As the Arrhenius law is not amenable analytically, it is approximated by a rational-cubic function. At the steady state the temperature versus power relationship is found to be multivalued; at the critical power level thermal runaway occurs when the temperature jumps from the lower (cool) temperature branch to the upper (hot) temperature branch of the solution. In the steady-state limit the approximate analytical solutions are compared with the numerical solutions of the governing equations for various special cases. These are the limits of small and large heat loss and an intermediate case involving radiative heat loss. Results are also presented for a case where differential cooling occurs on the different sides on the slab. An alternative heating scenario, where one end of the waveguide is blocked by a short, is also considered. The approximate solutions are found for this geometry and compared in the small Biot-number limit to Kriegsmann (1997). Also, a control process is presented, which allows thermal runaway to be avoided and the desired final steady state to be reached. Various special cases of the feedback parameters associated with the control process are examined. Keywords:microwave heating; thermal runway; Arrhenius law; control process; small thermal absorptivity

  1. Multiphysics Modeling of Microwave Heating of a Frozen Heterogeneous Meal Rotating on a Turntable.

    PubMed

    Pitchai, Krishnamoorthy; Chen, Jiajia; Birla, Sohan; Jones, David; Gonzalez, Ric; Subbiah, Jeyamkondan

    2015-12-01

    A 3-dimensional (3-D) multiphysics model was developed to understand the microwave heating process of a real heterogeneous food, multilayered frozen lasagna. Near-perfect 3-D geometries of food package and microwave oven were used. A multiphase porous media model combining the electromagnetic heat source with heat and mass transfer, and incorporating phase change of melting and evaporation was included in finite element model. Discrete rotation of food on the turntable was incorporated. The model simulated for 6 min of microwave cooking of a 450 g frozen lasagna kept at the center of the rotating turntable in a 1200 W domestic oven. Temperature-dependent dielectric and thermal properties of lasagna ingredients were measured and provided as inputs to the model. Simulated temperature profiles were compared with experimental temperature profiles obtained using a thermal imaging camera and fiber-optic sensors. The total moisture loss in lasagna was predicted and compared with the experimental moisture loss during cooking. The simulated spatial temperature patterns predicted at the top layer was in good agreement with the corresponding patterns observed in thermal images. Predicted point temperature profiles at 6 different locations within the meal were compared with experimental temperature profiles and root mean square error (RMSE) values ranged from 6.6 to 20.0 °C. The predicted total moisture loss matched well with an RMSE value of 0.54 g. Different layers of food components showed considerably different heating performance. Food product developers can use this model for designing food products by understanding the effect of thickness and order of each layer, and material properties of each layer, and packaging shape on cooking performance. PMID:26556025

  2. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part 1; Method and Uncertainties

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Kummerow, Christian D.; Yang, Song; Petty, Grant W.; Tao, Wei-Kuo; Bell, Thomas L.; Braun, Scott A.; Wang, Yansen; Lang, Stephen E.; Johnson, Daniel E.

    2004-01-01

    A revised Bayesian algorithm for estimating surface rain rate, convective rain proportion, and latent heating/drying profiles from satellite-borne passive microwave radiometer observations over ocean backgrounds is described. The algorithm searches a large database of cloud-radiative model simulations to find cloud profiles that are radiatively consistent with a given set of microwave radiance measurements. The properties of these radiatively consistent profiles are then composited to obtain best estimates of the observed properties. The revised algorithm is supported by an expanded and more physically consistent database of cloud-radiative model simulations. The algorithm also features a better quantification of the convective and non-convective contributions to total rainfall, a new geographic database, and an improved representation of background radiances in rain-free regions. Bias and random error estimates are derived from applications of the algorithm to synthetic radiance data, based upon a subset of cloud resolving model simulations, and from the Bayesian formulation itself. Synthetic rain rate and latent heating estimates exhibit a trend of high (low) bias for low (high) retrieved values. The Bayesian estimates of random error are propagated to represent errors at coarser time and space resolutions, based upon applications of the algorithm to TRMM Microwave Imager (TMI) data. Errors in instantaneous rain rate estimates at 0.5 deg resolution range from approximately 50% at 1 mm/h to 20% at 14 mm/h. These errors represent about 70-90% of the mean random deviation between collocated passive microwave and spaceborne radar rain rate estimates. The cumulative algorithm error in TMI estimates at monthly, 2.5 deg resolution is relatively small (less than 6% at 5 mm/day) compared to the random error due to infrequent satellite temporal sampling (8-35% at the same rain rate).

  3. Higher Fe{sup 2+}/total Fe ratio in iron doped phosphate glass melted by microwave heating

    SciTech Connect

    Mandal, Ashis K.; Sinha, Prasanta K.; Das, Dipankar; Guha, Chandan; Sen, Ranjan

    2015-03-15

    Highlights: • Iron doped phosphate glasses prepared using microwave heating and conventional heating under air and reducing atmosphere. • Presence of iron predominantly in the ferrous oxidation state in all the glasses. • Significant concentrations of iron in the ferrous oxidation state on both octahedral and tetrahedral sites in all the glasses. • Ratio of Fe{sup 2+} with total iron is found higher in microwave prepared glasses in comparison to conventional prepared glasses. - Abstract: Iron doped phosphate glasses containing P{sub 2}O{sub 5}–MgO–ZnO–B{sub 2}O{sub 3}–Al{sub 2}O{sub 3} were melted using conventional resistance heating and microwave heating in air and under reducing atmosphere. All the glasses were characterised by UV–Vis–NIR spectroscopy, Mössbauer spectroscopy, thermogravimetric analysis and wet colorimetry analysis. Mössbauer spectroscopy revealed presence of iron predominantly in the ferrous oxidation state on two different sites in all the glasses. The intensity of the ferrous absorption peaks in UV–Vis–NIR spectrum was found to be more in glasses prepared using microwave radiation compared to the glasses prepared in a resistance heating furnace. Thermogravimetric analysis showed increasing weight gain on heating under oxygen atmosphere for glass corroborating higher ratio of FeO/(FeO + Fe{sub 2}O{sub 3}) in glass melted by direct microwave heating. Wet chemical analysis also substantiated the finding of higher ratio Fe{sup +2}/ΣFe in microwave melted glasses. It was found that iron redox ratio was highest in the glasses prepared in a microwave furnace under reducing atmosphere.

  4. Numerical modeling of continuous flow microwave heating: a critical comparison of COMSOL and ANSYS.

    PubMed

    Salvi, D; Boldor, Dorin; Ortego, J; Aita, G M; Sabliov, C M

    2010-01-01

    Numerical models were developed to simulate temperature profiles in Newtonian fluids during continuous flow microwave heating by one way coupling electromagnetism, fluid flow, and heat transport in ANSYS 8.0 and COMSOL Multiphysics v3.4. Comparison of the results from the COMSOL model with the results from a pre-developed and validated ANSYS model ensured accuracy of the COMSOL model. Prediction of power Loss by both models was in close agreement (5-13% variation) and the predicted temperature profiles were similar. COMSOL provided a flexible model setup whereas ANSYS required coupling incompatible elements to transfer load between electromagnetic, fluid flow, and heat transport modules. Overall, both software packages provided the ability to solve multiphysics phenomena accurately. PMID:21721467

  5. Coupled electromagnetic and thermal modeling of microwave oven heating of foods.

    PubMed

    Zhang, H; Datta, A K

    2000-01-01

    Temperature distributions from heating in a domestic microwave oven were studied by considering the coupling between the electromagnetics and heat transfer through changes in dielectric properties during heating. Maxwell's equations for electromagnetics and the thermal energy equations are solved numerically using two separate finite-element softwares. The coupling between the softwares was developed by writing special modules that interfaced these softwares at the system level. Experimentally measured temperature profiles were compared with the numerical predictions. The importance of coupling was evident when the properties changed significantly with temperature for low and high dielectric loss materials and more so for the high loss materials. For moderate loss materials, when the properties do not change as much with temperature, coupled solutions lead to results very close to the results for the uncoupled solution. PMID:10935193

  6. Hydrothermal carbonization of sugarcane bagasse via wet torrefaction in association with microwave heating.

    PubMed

    Chen, Wei-Hsin; Ye, Song-Ching; Sheen, Herng-Kuang

    2012-08-01

    Hydrothermal carbonization of sugarcane bagasse using wet torrefaction is studied. The biomass is torrefied in water or dilute sulfuric acid solution and microwaves are employed to heat the solutions where the reaction temperature is fixed at 180 °C. The effects of acid concentration, heating time and solid-to-liquid ratio on the performance of wet torrefaction are investigated. It is found that the addition of sulfuric acid and increasing heating time are conducive to carbonizing bagasse. The calorific value of bagasse can be increased up to 20.3% from wet torrefaction. With the same improvement in calorific value, the temperature of wet torrefaction is lower than that of dry torrefaction around 100 °C, revealing that wet torrefaction is a promising method to upgrade biomass as fuel. The calorific value of torrefied biomass can be predicted well based on proximate, elemental or fiber analysis, and the last one gives the best estimation. PMID:22705524

  7. Electron heating due to microwave photoexcitation in the high mobility GaAs/AlGaAs two dimensional electron system

    NASA Astrophysics Data System (ADS)

    Ramanayaka, A. N.; Mani, R. G.; Wegscheider, W.

    2013-12-01

    We extract the electron temperature in the microwave photo-excited high mobility GaAs/AlGaAs two dimensional electron system (2DES) by studying the influence of microwave radiation on the amplitude of Shubnikov-de Haas oscillations (SdHOs) in a regime where the cyclotron frequency, ωc, and the microwave angular frequency, ω, satisfy 2ω ≤ ωc ≤ 3.5ω The results indicate that increasing the incident microwave power has a weak effect on the amplitude of the SdHOs and therefore the electron temperature, in comparison to the influence of modest temperature changes on the dark-specimen SdH effect. The results indicate negligible electron heating under modest microwave photo-excitation, in good agreement with theoretical predictions.

  8. Electron heating due to microwave photoexcitation in the high mobility GaAs/AlGaAs two dimensional electron system

    SciTech Connect

    Ramanayaka, A. N.; Mani, R. G.; Wegscheider, W.

    2013-12-04

    We extract the electron temperature in the microwave photo-excited high mobility GaAs/AlGaAs two dimensional electron system (2DES) by studying the influence of microwave radiation on the amplitude of Shubnikov-de Haas oscillations (SdHOs) in a regime where the cyclotron frequency, ω{sub c}, and the microwave angular frequency, ω, satisfy 2ω ≤ ω{sub c} ≤ 3.5ω The results indicate that increasing the incident microwave power has a weak effect on the amplitude of the SdHOs and therefore the electron temperature, in comparison to the influence of modest temperature changes on the dark-specimen SdH effect. The results indicate negligible electron heating under modest microwave photo-excitation, in good agreement with theoretical predictions.

  9. Enhancing Oxidative Stability of Sunflower Oil during Convective and Microwave Heating Using Grape Seed Extract

    PubMed Central

    Poiana, Mariana-Atena

    2012-01-01

    This study was performed to investigate the effectiveness of grape seed extract (GSE) compared to butylated hydroxytoluene (BHT) on retarding lipid oxidation of sunflower oil subjected to convection and microwave heating up to 240 min under simulated frying conditions. The progress of lipid oxidation was assessed in terms of peroxide value (PV), p-anisidine value (p-AV), conjugated dienes and trienes (CD, CT), inhibition of oil oxidation (IO) and TOTOX value. In addition, total phenolic content (TP) was evaluated in samples before and after heating in order to assess the changes in these compounds relative to the extent of lipid oxidation. The results of this study highlight that GSE showed a significantly inhibitory effect on lipid oxidation during both treatments, although to a different extent. This ability was dose-dependent; therefore, the extent of lipid oxidation was inversely related to GSE level. Convective heating, respective microwave exposure for 240 min of samples supplemented by GSE to a level of 1000 ppm, resulted in significant decreases of investigated indices relative to the control values as follows: PV (48%; 30%), p-AV (29%; 40%), CD (45%; 30%), CT (41%; 36%), TOTOX (35%; 37%). GSE to a level of 600–800 ppm inhibited the lipid oxidation in a similar manner to BHT. These results suggested that GSE can be used as a potential natural extract for improving oxidative stability of sunflower oil during thermal applications. PMID:22942764

  10. High-power microwave transmission and launching systems for fusion plasma heating systems

    SciTech Connect

    Bigelow, T.S.

    1989-01-01

    Microwave power in the 30- to 300-GHz frequency range is becoming widely used for heating of plasma in present-day fusion energy magnetic confinement experiments. Microwave power is effective in ionizing plasma and heating electrons through the electron cyclotron heating (ECH) process. Since the power is absorbed in regions of the magnetic field where resonance occurs and launching antennas with narrow beam widths are possible, power deposition location can be highly controlled. This is important for maximizing the power utilization efficiency and improving plasma parameters. Development of the gyrotron oscillator tube has advanced in recent years so that a 1-MW continuous-wave, 140-GHz power source will soon be available. Gyrotron output power is typically in a circular waveguide propagating a circular electric mode (such as TE/sub 0,2/) or a whispering-gallery mode (such as TE/sub 15,2/), depending on frequency and power level. An alternative high-power microwave source currently under development is the free-electron laser (FEL), which may be capable of generating 2-10 MW of average power at frequencies of up to 500 GHz. The FEL has a rectangular output waveguide carrying the TE/sub 0,1/ mode. Because of its higher complexity and cost, the high-average-power FEL is not yet as extensively developed as the gyrotron. In this paper, several types of operating ECH transmission systems are discussed, as well systems currently being developed. The trend in this area is toward higher power and frequency due to the improvements in plasma density and temperature possible. Every system requires a variety of components, such as mode converters, waveguide bends, launchers, and directional couplers. Some of these components are discussed here, along with ongoing work to improve their performance. 8 refs.

  11. Detection of carbon nanotubes in plant roots through microwave-induced heating

    NASA Astrophysics Data System (ADS)

    Irin, Fahmida; Shrestha, Babina; Canas, Jaclyn; Saed, Mohammad; Green, Micah

    2012-02-01

    We demonstrate a novel technique for quantitative detection of CNTs in biological samples by utilizing the thermal response of CNTs under microwave irradiation. In particular, rapid heating of CNTs due to microwave absorption was employed to quantify the amount of CNTs present in alfalfa plant roots. Alfalfa roots were prepared by injecting a known amount of CNTs (single walled and multi walled) and exposed to 30-50 W microwave power to generate calibration curves (temperature rise vs. CNT mass). These calibration curves serve as a characterization tool to determine the unknown amount of CNTs absorbed by alfalfa plant roots grown in CNT-laden soil with superior accuracy and sensitivity. Moreover, the threshold for detectable CNT concentration is much lower than common analytical methods of detecting nanomaterials, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Considering the lack of effective detection methods for CNT uptake in plants, this method is not only unique but also practical, as it addresses a major problem in the field of nanotoxicology risk assessment.

  12. Prediction of heating patterns of a microwave interstitial antenna array at various insertion depths.

    PubMed

    Zhang, Y; Joines, W T; Oleson, J R

    1991-01-01

    Measurements made on the interstitial microwave antennas used for hyperthermia cancer therapy indicate that the heating patterns vary with the insertion depths (defined as the distance from the antenna tip to air-tissue interface). The antennas are made of thin coaxial cables with a radiation gap or gaps on the outer conductor. The antennas are inserted into small polypropylene catheters implanted in the tumour volume. This type of antenna may be simulated as an asymmetric dipole with one arm being the tip section consisting of the expanded extension of the inner conductor, and the other arm being the section of the outer conductor from the gap to the insertion point (air-tissue interface). We use four of the antennas to form a 2 cm x 2 cm array. The antennas are positioned on the corners of a 2 cm square. Measurements on both single antennas and multi-antenna arrays show that the maximum heating is not stationary with position along the antenna when the depth of insertion is changed. This paper investigates the theoretical prediction of the changes in heating patterns of interstitial microwave antennas at different insertion depths. Each of the antennas in the array is simulated as an asymmetric dipole. The SAR (specific absorption rate) is computed by using the insulated dipole theory. The temperature distribution in absence of perfusion is obtained through a thermal simulation routine to convert the SAR pattern into the temperature pattern. Excellent qualitative agreement is found between the theoretical heating pattern and the measured pattern in a non-perfused phantom on a 2 cm x 2 antenna array. Since the insertion depths of the interstitial antennas are different from patient to patient, it is recommended that simulation of the heating be done before treatments, to confirm the delivery of power to the target region. PMID:2051073

  13. Microwave heating inactivates Shiga Toxin (Stx2) in reconstituted fat-free Milk and adversely affects the nutritional value of cell culture medium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microwave exposure is a convenient and widely used method for defrosting, heating, and cooking numerous foods. Microwave cooking is also reported to kill pathogenic microorganisms that often contaminate food. Microwaves act by causing polar molecules in food, such as water, to rapidly rotate, thus...

  14. Microwave-assisted cross-coupling and hydrogenation chemistry by using heterogeneous transition-metal catalysts: an evaluation of the role of selective catalyst heating.

    PubMed

    Irfan, Muhammed; Fuchs, Michael; Glasnov, Toma N; Kappe, C Oliver

    2009-11-01

    The concept of specific microwave effects in solid/liquid catalytic processes resulting from the selective heating of a microwave-absorbing heterogeneous transition-metal catalyst by using 2.45 GHz microwave irradiation was evaluated. As model transformations Ni/C-, Cu/C-, Pd/C-, and Pd/Al2O3-catalyzed carbon-carbon/carbon-heteroatom cross-couplings and hydrogenation reactions were investigated. To probe the existence of specific microwave effects by means of selective catalyst heating in these transformations, control experiments comparing microwave dielectric heating and conventional thermal heating at the same reaction temperature were performed. Although the supported metal catalysts were experimentally found to be strongly microwave absorbing, for all chemistry examples investigated herein no differences in reaction rate or selectivity between microwave and conventional heating experiments under carefully controlled conditions were observed. This was true also for reactions that use low-absorbing or microwave transparent solvents, and was independent of the microwave absorbtivity of the catalyst support material. In the case of hydrogenation reactions, the stirring speed was found to be a critical factor on the mass transfer between gas and liquid phase, influencing the rate of the hydrogenation in both microwave and conventionally heated experiments. PMID:19774573

  15. Optimization of hydrous ferrous sulfate dehydration by microwave heating using response surface methodology.

    PubMed

    Yu, Yan-Tao; Liu, Bing-Guo; Chen, Guo; Peng, Jin-Hui; Srinivasakannan, C

    2012-01-01

    The work relates to assessing the ability of the microwave for dehydration of large amount of waste hydrous ferrous sulfate generated from the titanium pigment process industry. The popular process optimization tool of response surface methodology with central composite design was adopted to estimate the effect of dehydration. The process variables were chosen to be power input, duration of heating and the bed thickness, while the response variable being the weight loss. An increase in all the three process variables were found to significantly increase the weight loss, while the effect of interaction among the parameters were found to be insignificant. The optimized process conditions that contribute to the maximum weight loss were identified to be a power input of 960 W, duration of heating of 14 min and bed thickness of 5 cm, resulting in a weight loss of 31.44%. The validity of the optimization process was tested with the repeat runs at optimized conditions. PMID:24432588

  16. In situ growth of silver nanoparticles on TEMPO-oxidized jute fibers by microwave heating.

    PubMed

    Cao, Xinwang; Ding, Bin; Yu, Jianyong; Al-Deyab, Salem S

    2013-01-30

    Cellulose fibers deposited with metallic nanoparticles as one kind of renewable, biocompatible and antimicrobial nanomaterials evoke much interest because of their versatility in various applications. Herein, for the first time, a facile, simple and rapid method was developed to fabricate TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) selectively oxidized jute fibers in situ deposited with silver nanoparticles in the absence of reducing reagents. The average size of silver nanoparticles deposited on the fibers is 50.0 ± 2.0 nm by microwave heating for 5 min and 90.0 ± 4.7 nm for 10 min heating sample, respectively. The versatile jute-silver nanoparticles nanocomposites with superior thermal stability and high crystallinity would be particularly useful for applications in the public health care and biomedical fields. PMID:23218337

  17. Enhanced microwave absorbing properties and heat resistance of carbonyl iron by electroless plating Co

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-11-01

    Co coated carbonyl iron particles (Co (CI)) are fabricated through electroless plating method, and the electromagnetic microwave absorbing properties are investigated in the frequencies during 8.2-12.4 GHz. The complex permittivity of CI particles after electroless plating Co is higher than that of raw CI particles due to improvment of the polarization process. Furthermore, according to the XRD and TG results, the Co layer can enhance the heat resistance of CI particles. The bandwidth below -10 dB can reach 3.9 GHz for the Co(CI) absorbent. The results indicate that the electroless plating Co not only enhances the absorbing properties but also improves the heat resistance of CI.

  18. Microwave oven heating for inactivation of Listeria monocytogenes on frankfurters before consumption.

    PubMed

    Rodríguez-Marval, Mawill; Geornaras, Ifigenia; Kendall, Patricia A; Scanga, John A; Belk, Keith E; Sofos, John N

    2009-10-01

    Microwave oven heating was evaluated for inactivation of Listeria monocytogenes on inoculated and stored frankfurters. Frankfurters formulated without/with 1.5% potassium lactate and 0.1% sodium diacetate were inoculated with L. monocytogenes (1.9 +/- 0.2 log CFU/cm(2)), vacuum-packaged, and stored (4 degrees C) to simulate conditions prior to purchase by consumers. At storage days 18, 36, and 54, packages were opened and placed at 7 degrees C, simulating aerobic storage in a household refrigerator. At 0, 3, and 7 d of aerobic storage, 2 frankfurters were placed in a bowl with water (250 mL) and treated in a household microwave oven at high (1100 W) power for 30, 45, 60, or 75 s, or medium (550 W) power for 60 or 75 s. Frankfurters and the heating water were analyzed for total microbial counts and L. monocytogenes populations. Exposure to high power for 75 s reduced pathogen levels (0.7 +/- 0.0 to 1.0 +/- 0.1 log CFU/cm(2)) to below the detection limit (<-0.4 log CFU/cm(2)) on frankfurters with lactate/diacetate, even after 54 d of vacuum-packaged storage followed by 7 d of aerobic storage. For frankfurters without lactate/diacetate, high power for 75 s caused reductions between > 1.5 and 5.9 log CFU/cm(2) from control levels of 1.5 +/- 0.1 to 7.2 +/- 0.5 log CFU/cm(2). Depending on treatment and storage time, the water used to reheat the frankfurters had viable L. monocytogenes counts of <-2.4 to 5.5 +/- 0.5 log CFU/mL. The results indicated that frankfurters should be reheated in a microwave oven at high power for 75 s to inactivate up to 3.7 log CFU/cm(2) of L. monocytogenes contamination. PMID:19799673

  19. Thermoelectric properties of bulk MoSi2 synthesized by solid state microwave heating

    NASA Astrophysics Data System (ADS)

    Lan, Yu; Xie, Mianyu; Ouyang, Ting; Yue, Song

    2016-07-01

    In this research, single phase α-MoSi2 was prepared by solid state hybrid microwave heating within 90 min at relatively low temperature 1273 K. Such precursor powders were then ball milled and sintered by microwave heating at different temperatures. The thermoelectric (TE) properties of MoSi2 bulks were investigated in the temperature range of 300-673 K. When the sintering temperature increases from 973 K to 1273 K, the electrical resistivity decreases significantly and the Seebeck coefficients increase obviously, leading to the maximum TE powder factor of 6.2 × 10‑6Wm‑1K‑2 at 673 K. These results demonstrate the feasibility of high efficient and economical synthesis of MoSi2 by microwave heating technique, with the final products having comparable TE performance in comparison to those from typical methods with long duration and energy-extensive consumption.

  20. Dynamics of glass-forming liquids. XIII. Microwave heating in slow motion

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Richert, Ranko

    2009-05-01

    Using time-resolved nonlinear dielectric relaxation measurements at fields as high as 450 kV/cm, the nonthermal effects of energy absorption are studied for simple and associating polar liquids in their supercooled state. The experiment is a low frequency analog of microwave heating and facilitates tracking the flow of energy in time, as it accumulates in slow degrees of freedom and transfers eventually to the vibrational heat bath of the liquid. Most findings agree with a phenomenological model of heterogeneous relaxation regarding structure and configurational temperature. The relevant thermal behavior of monohydroxy alcohols differs considerably from the cases of simple nonassociating liquids due to their distinct origins of the prominent dielectric absorption mode for the two classes of liquids. Nonthermal effects are observed as dynamics that are accelerated without increasing sample temperature, but for the present low frequencies the changes remain too small to explain the high efficiencies reported for microwave chemistry. Limitations as to how rapidly the faster relaxation time constants are able to adjust to temperature separate the modes of the dispersive α-relaxation into a "relaxation" and an "aging" regime, thereby explaining the incompatibility of heterogeneous dynamics with common physical aging observations.

  1. Microwave-heating synthesis and sensing applications of bright gold nanoclusters

    SciTech Connect

    He, Ding-Fei; Xiang, Yang; Wang, Xu; Yu, Xue-Feng

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We establish a microwave-heating method to synthesize protein-stabilized Au nanoclusters. Black-Right-Pointing-Pointer The obtained Au nanoclusters show bright red fluorescence. Black-Right-Pointing-Pointer The Au nanoclusters can be used as efficient fluorescence probe for Cu{sup 2+} ion sensing. -- Abstract: A rapid microwave-heating method has been developed for the synthesis of bright Au nanoclusters by using bull serum albumin as the template in an aqueous environment. The reaction time needed is only 7.0 min, and the weight of the products at one batch can reach 15 g. The Au nanoclusters exhibit bright fluorescence at {approx}613 nm with quantum yield of {approx}6.0%. By adjusting the pH value, the products can be controlled to precipitate or re-disperse in aqueous solution. Furthermore, the Au nanoclusters have exhibited high sensitivity and selectivity in the determination of Cu{sup 2+} ions in water. These results suggest an efficient method for obtaining metal nanoclusters for the detection and sensing applications.

  2. A Kinetic Study of Indium Leaching from Indium-Bearing Zinc Ferrite Under Microwave Heating

    NASA Astrophysics Data System (ADS)

    Zhang, Linye; Mo, Jiamei; Li, Xuanhai; Pan, Liuping; Liang, Xinyuan; Wei, Guangtao

    2013-12-01

    To obtain information about leaching reaction and kinetics of indium from indium-bearing materials under microwave heating (MH), leaching of indium from indium-bearing zinc ferrite (IBZF) has been investigated. IBZF samples under MH and under conventional heating (CH) were studied by X-ray diffraction and specific surface area. Compared with that of CH, the effect of MH and the effects of various control parameters on indium leaching were studied. The results showed that compared with CH, MH enhanced the indium leaching from IBZF and increased the leaching rate. The leaching behavior of indium from IBZF was analyzed by unreacted shrinking core model, and the regression of kinetic equations showed that leaching of indium from IBZF obeyed the model very well. The activation energies under MH and under CH were 77.374 kJ/mol and 53.555 kJ/mol, respectively; the ratio of frequency factor K 0(MH)/ K 0(CH) was 10,818.36. The activation mechanism involved in leaching of indium under MH was mainly the increase of reactant energy and effective collision, which caused by the thermal and nonthermal microwave effect. Compared with the activation energy, the effective collision played a more important role in the acceleration of leaching of indium.

  3. Rheological analysis of sucrose solution at high temperatures using a microwave-heated pressurized capillary rheometer.

    PubMed

    Ros-Polski, Valquíria; Schmidt, Flávio L; Vitali, Alfredo A; Marsaioli, Antonio; Raghavan, Vijaya G S

    2014-04-01

    Thermal process design, optimization, and deviation require the knowledge of engineering properties of food, such as rheological behavior, which is highly dependent on temperature. If a process is calculated based on the parameters obtained by extrapolation, it might lead to over- or underprocessing. The long time required for the product to reach the desired temperature, which is usual in many rheometers, may induce unexpected changes on the product. Model solutions are often used in engineering projects in order to simulate characteristics of real products. Thus, the objective of this study was to obtain rheological data of sucrose model solution at the actual high UHT (ultra-high temperature) process temperatures using a pressurized capillary rheometer, heated by a microwave system. The results provide the rheological behavior of the sucrose solutions and show that there is no deviation of the linearity of the Arrhenius plot above 100 °C for this product. This work was useful to illustrate the use of the applied methodology and to validate the newly built microwave-heated capillary rheometer. The data obtained confirm the stability of nonsaturated sucrose solution when treated above 100 °C and presents an important contribution to the literature database, since sucrose solutions are used as models for many table syrups, such as maple and sorghum syrups. PMID:24597707

  4. Pulsed microwave heating method for preparation of dye-sensitized solar cells for greener, faster, cheaper production of photovoltaic materials

    NASA Astrophysics Data System (ADS)

    Murphy, Clifford B.; Cotta, Robert; Blais, Timothy; Hall, Charles B.

    2015-05-01

    Microwave heating methods are very popular for developing chemical syntheses that are achieved much more rapidly or with less solvent than via conventional heating methods. Their application to solar cell development has been primarily in developing improvements in the synthesis of dyes and curing of polymer substrates, but not in assisting the photoanode construction of dye-sensitized solar cells. Microwave heating of conducting substrates can lead to arcing of electricity in the reactor, which in turn, can lead to extensive degradation or complete destruction of the photoanode. Here we present our work in applying a pulsed microwave heating method that affords quicker dye deposition times in comparison to conventional heating (μw 40 min, conventional 60 min) with similar dye concentrations as characterized by UV-Vis absorbance, contact angle measurements, and cyclic voltammetry. Our photoanodes are constructed with anatase TiO2 cured onto FTO glass, and deposition of the N719 ruthenium dye either directly to the TiO2 layer or through amide bond formation to a silane layer that has been deposited on the TiO2 layer. Modest improvements in the solar energy conversion efficiency are shown through the microwave method in comparison to conventional heating (μw 0.78% vs. conventional 0.25% reported by K. Szpakolski, et. Al. Polyhedron, 2013, 52, 719-732.)

  5. Comparison of Microwave and Conventional Heating of a Wheat Starch-Gluten Model System

    NASA Astrophysics Data System (ADS)

    Umbach, Sharon Lynn

    The effects of conventional (CV) and microwave (MW) heating on a model wheat starch, vital wheat gluten system were studied. Three moisture contents (35%, 50%, and 65%) and up to five ratios of starch:gluten were studied. MW power was such that heating took place more quickly than during CV heating conditions. Temperature profiles during heating showed the importance of moisture content for curve shape and that all samples reached a high enough temperature for starch gelatinization and gluten denaturation to occur. Scanning electron microscopy supported temperature data in that physical changes for starch had taken place. Texture was evaluated as the force required to compress the sample. Differences were found for heating method, moisture content, and sample composition. Moisture content had the major effect and was inversely related to force. In general, CV heated samples required more force to compress than the MW heated samples. The high starch samples at 50% moisture showed the opposite affect. Self-diffusion coefficients determined by nuclear magnetic resonance (NMR) showed that there was a redistribution of water between starch and gluten after heating for the faster more mobile water in the samples. Little difference was found between the two heating methods. The attenuation factor which has based on the dielectric constant and loss showed differences in the way the sample interacted with electromagnetic energy. The gluten was fractioned with dilute HCl to give six groups of protein. Starch appeared to have an effect on how the gluten denatured. When the fractions were characterized with SDS-PAGE it was found that each fraction contained a wide range of proteins with different molecular weights. Differences were found in the band patterns between the CV- and MW -heated samples. ^{13}C NMR also was used, which provided information on the protein and carbohydrate component of the fractions showed differences between the CV and MW heated samples, especially

  6. Novel Direct Steelmaking by Combining Microwave, Electric Arc, and Exothermal Heating Technologies

    SciTech Connect

    Dr. Xiaodi Huang; Dr. J. Y. Hwang

    2005-03-28

    Steel is a basic material broadly used by perhaps every industry and individual. It is critical to our nation's economy and national security. Unfortunately, the American steel industry is losing competitiveness in the world steel production field. There is an urgent need to develop the next generation of steelmaking technology for the American steel industry. Direct steelmaking through the combination of microwave, electric arc, and exothermal heating is a revolutionary change from current steelmaking technology. This technology can produce molten steel directly from a shippable agglomerate, consisting of iron oxide fines, powdered coal, and ground limestone. This technology is projected to eliminate many current intermediate steelmaking steps including coking, pellet sintering, blast furnace (BF) ironmaking, and basic oxygen furnace (BOF) steelmaking. This technology has the potential to (a) save up to 45% of the energy consumed by conventional steelmaking; (b) dramatically reduce the emission of CO{sub 2}, SO{sub 2}, NO{sub x}, VOCs, fine particulates, and air toxics; (c) substantially reduce waste and emission control costs; (d) greatly lower capital cost; and (e) considerably reduce steel production costs. This technology is based on the unique capability of microwaves to rapidly heat steelmaking raw materials to elevated temperature, then rapidly reduce iron oxides to metal by volumetric heating. Microwave heating, augmented with electric arc and exothermal reactions, is capable of producing molten steel. This technology has the components necessary to establish the ''future'' domestic steel industry as a technology leader with a strong economically competitive position in world markets. The project goals were to assess the utilization of a new steelmaking technology for its potential to achieve better overall energy efficiency, minimize pollutants and wastes, lower capital and operating costs, and increase the competitiveness of the U.S. steel industry. The

  7. Regional brain heating during microwave exposure (2.06 GHz), warm-water immersion, environmental heating and exercise.

    PubMed

    Walters, T J; Ryan, K L; Belcher, J C; Doyle, J M; Tehrany, M R; Mason, P A

    1998-01-01

    Nonuniform heating may result from microwave (MW) irradiation of tissues and is therefore important to investigate in terms of health and safety issues. Hypothalamic (Thyp), cortical (Tctx), tympanic (Tty), and rectal (Tre) temperatures were measured in rats exposed in the far field, k-polarization (i.e., head pointed toward the transmitter horn and E-field in vertical direction) to two power densities of 2.06 GHz irradiation. The high-power density (HPM) was 1700 mW/cm2 [specific absorption rate (SAR): hypothalamus 1224 W/kg; cortex 493 W/kg]; the low-power density (LPM) was 170 mW/cm2 (SAR: hypothalamus 122.4 W/kg; cortex 49.3 W/kg). The increase (rate-of-rise, in degrees C/s) in Thyp was significantly greater than those in Tctx or Tre when rats were exposed to HPM. LPM produced more homogeneous heating. Quantitatively similar results were observed whether rats were implanted with probes in two brain sites or a single probe in one or the other of the two sites. The qualitative difference between regional brain heating was maintained during unrestrained exposure to HPM in the h-polarization (i.e., body parallel to magnetic field). To compare the temperature changes during MW irradiation with those produced by other modalities of heating, rats were immersed in warm water (44 degrees C, WWI); exposed to a warm ambient environment (50 degrees C, WSED); or exercised on a treadmill (17 m/min 8% grade) in a warm ambient environment (35 degrees C, WEX). WWI produced uniform heating in the regions measured. Similar rates-of-rise occurred among regions following WSED or WEX, thus maintaining the pre-existing gradient between Thyp and Tctx These data indicate that HPM produced a 2-2.5-fold difference in the rate-of-heating within brain regions that were separated by only a few millimeters. In contrast, more homogeneous heating was recorded during LPM or nonmicrowave modalities of heating. PMID:9738525

  8. Inactivation of Salmonella Senftenberg, Salmonella Typhimurium and Salmonella Tennessee in peanut butter by 915 MHz microwave heating.

    PubMed

    Song, Won-Jae; Kang, Dong-Hyun

    2016-02-01

    This study evaluated the efficacy of a 915 MHz microwave with 3 different levels to inactivate 3 serovars of Salmonella in peanut butter. Peanut butter inoculated with Salmonella enterica serovar Senftenberg, S. enterica serovar Typhimurium and S. enterica serovar Tennessee were treated with a 915 MHz microwave with 2, 4 and 6 kW and acid and peroxide values and color changes were determined after 5 min of microwave heating. Salmonella populations were reduced with increasing treatment time and treatment power. Six kW 915 MHz microwave treatment for 5 min reduced these three Salmonella serovars by 3.24-4.26 log CFU/g. Four and two kW 915 MHz microwave processing for 5 min reduced these Salmonella serovars by 1.14-1.48 and 0.15-0.42 log CFU/g, respectively. Microwave treatment did not affect acid, peroxide, or color values of peanut butter. These results demonstrate that 915 MHz microwave processing can be used as a control method for reducing Salmonella in peanut butter without producing quality deterioration. PMID:26678129

  9. Preparation of activated carbon from coconut shell chars in pilot-scale microwave heating equipment at 60 kW

    SciTech Connect

    Li Wei; Peng Jinhui Zhang Libo; Yang Kunbin; Xia Hongying; Zhang Shimin; Guo Shenghui

    2009-02-15

    Experiments to prepare activated carbon by microwave heating indicated that microwave energy can decrease reaction temperature, save the energy and shorten processing time remarkably compared to conventional heating, owing to its internal and volumetric heating effects. The above results were based on the laboratory-scale experiments. It is desirable to develop a pilot-scale microwave heating equipment and investigate the parameters with the aim of technological industrialization. In the present study, the components and features of the self-invented equipment were introduced. The temperature rise curves of the chars were obtained. Iodine numbers of the activated carbons all exceed the state standard of China under the following conditions: 25 kg/h charging rate, 0.42 rev/min turning rate of ceramic tube, flow rate of steam at pressure of 0.01 MPa and 40 kW microwave heating power after 60 kW pre-activation for 30 min. Pore structure of the sample obtained at a time point of 46 h, which contained BET surface area, and pore size distributions of micropores and total pores, was tested by nitrogen adsorption at 77 K.

  10. Microwave thermal imaging: initial in vivo experience with a single heating zone.

    PubMed

    Meaney, P M; Fanning, M W; Paulsen, K D; Lit, D; Pendergrass, S A; Fang, Q; Moodie, K L

    2003-01-01

    The deployment of hyperthermia as a routine adjuvant to radiation or chemotherapy is limited largely by the inability to devise treatment plans which can be monitored through temperature distribution feedback during therapy. A non-invasive microwave tomographic thermal imaging system is currently being developed which has previously exhibited excellent correlation between the recovered electrical conductivity of a heated zone and its actual temperature change during phantom studies. To extend the validation of this approach in vivo, the imaging system has been re-configured for small animal experiments to operate within the bore of a CT scanner for anatomical and thermometry registration. A series of 5-7 day old pigs have been imaged during hyperthermia with a monopole antenna array submerged in a saline tank where a small plastic tube surgically inserted the length of the abdomen has been used to create a zone of heated saline at pre-selected temperatures. Tomographic microwave data over the frequency range of 300-1000 MHz of the pig abdomen in the plane perpendicular to the torso is collected at regular intervals after the tube saline temperatures have settled to the desired settings. Images are reconstructed over a range of operating frequencies. The tube location is clearly visible and the recovered saline conductivity varies linearly with the controlled temperature values. Difference images utilizing the baseline state prior to heating reinforces the linear relationship between temperature and imaged saline conductivity. Demonstration of in vivo temperature recovery and correlation with an independent monitoring device is an important milestone prior to clinical integration of this non-invasive imaging system with a thermal therapy device. PMID:14756452

  11. Effects of different additives with assistance of microwave heating for heavy metal stabilization in electronic industry sludge.

    PubMed

    Jothiramalingam, R; Lo, Shang-Lien; Chen, Ching-lung

    2010-01-01

    Electronic industrial wastewater sludge in Taiwan is normally passed through an acid-extraction process to reclaim most of the copper ions, the remaining residue may still need to be treated by various stabilization technologies using suitable additives. Cement solidification is used as the common method to stabilize the industrial wastewater sludge in Taiwan. However, this method has the disadvantage of an increase in waste volume. In the present study selective additives such as sodium sulfide, barium manganate and different phase of alumina were tested as a possible alternate additive to stabilize the heavy metal ion in the treated solid waste sludge via microwave heating treatment. The effects of additive amount, power of microwave irradiation and reaction time have been studied. Heavy metal leaching capacity is determined by using standard toxicity characteristic leaching procedure test and elemental content in the leachate is analyzed by inductively coupled plasma analysis. Sodium sulfide is effectively stabilizing the leaching copper ion with high selectivity in the presence of microwave irradiation and finally stabilized in the form of copper sulfide, which is a significant reaction to stabilize the copper ion leaching in the waste sludge. Complete stabilization of heavy metal ion and copper ion content (<5mgL(-1)) in industrial sludge is achieved by heating the microwave treated barium manganate and alumina additives by adopting suitable reaction conditions. Hybrid microwave and conventional heating process with minor amount of additive providing the efficient heavy metal stabilization for treated electronic industry waste sludge. PMID:19945139

  12. Conventional heating vs. microwave sludge pretreatment comparison under identical heating/cooling profiles for thermophilic advanced anaerobic digestion.

    PubMed

    Hosseini Koupaie, E; Eskicioglu, C

    2016-07-01

    This research evaluates whether there is any advantage of selecting one of the thermal methods of sludge pretreatment, conventional heating (CH) and microwave hydrolysis (MW), over another to enhance municipal sludge disintegration and performance of thermophilic anaerobic digestion (AD). For this purpose, a custom-built CH system simulating MW hydrolysis under identical heating and cooling profiles was used. The effects of three main pretreatment parameters including pretreatment method (CH and MW), heating ramp rate (3, 6 and 11°C/min) and final temperature (80, 120 and 160°C) on sludge solubilization and performance of thermophilic batch AD were evaluated. The effects of CH and MW hydrolysis were observed to be similar for sludge disintegration and digester performance (p-value>0.05), while the effects of final temperature and heating ramp rate were proven to be different (p-value<0.05). According to the results, it is essential to apply MW and CH pretreatments under identical experimental condition for an unbiased comparison which supports the findings of the author's earlier study under mesophilic condition. Failing to address this issue explains the significant inconsistency observed among the findings of the previous CH vs. MW comparison studies that were unable to implement identical thermal profiles (between CH and MW) during sludge pretreatment. In comparison with mesophilic AD, thermophilic AD revealed lower biodegradation rate constant at the highest pretreatment temperature tested (160°C), suggesting its higher sensitivity to the inhibitory effects of thermal pretreatment at the elevated temperatures. PMID:27160636

  13. Stability of Continental Lithosphere based on Analogue Experiments with Microwave Induced Internal Heating

    NASA Astrophysics Data System (ADS)

    Fourel, Loic; Limare, Angela; Surducan, Emanoil; Surducan, Vasile; Neamtu, Camelia; Vilella, Kenny; Farnetani, Cinzia; Kaminski, Edouard; Jaupart, Claude

    2015-04-01

    Continental lithosphere is usually depicted as the upper conductive layer of the Earth. Its formation is achieved through melt depletion that generates a residue that is less dense and more viscous than the underlying convecting mantle. As it is cooled from above, continental lithosphere can develop its own convective currents and may become unstable depending on its thickness and density contrast with the mantle. But chemical differentiation due to mantle magmatism also enriches continental lithosphere in heat producing elements. According to present estimates, the Earth's mantle may have lost as much as half of its radioactive elements in favour of continental crust and this stratified redistribution of heat sources has two main effects. First, mantle convection vigor decreases and becomes increasingly sensitive to heat supply from the core. Second, localized heat production at the top surface increases the continental insulating effects and competes against lithospheric instabilities. In the present study, we focus on the later and we determine which amount of internal heating is required to keep the lithosphere stable for a given rate of cooling from the top. The physics underlying instability triggering corresponds to the problem of a two differentially heated layered system cooled from above, where the top layer is less dense and more viscous than the bottom one, representative of the lithosphere-mantle system. Few studies have been devoted to the intrinsic characteristics of this layered type of convection. Here, we present a state of the art laboratory setup to generate internal heating in controlled conditions based on microwave (MW) absorption. The volumetric heat source can be localized in space and its intensity can be varied in time. Our tank prototype has horizontal dimensions of 30 cm x 30 cm and 5 cm height. A uniform and constant temperature is maintained at the upper boundary by an aluminium heat exchanger and adiabatic conditions are imposed at

  14. Passive and Active Microwave Remote Sensing of Precipitation and Latent Heating Distributions in the Tropics from TRMM

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Kummerow, Christian D.; Yang, Song; Haddad, Ziad S.; Tao, Wei-Kuo; Wang, Yansen; Lang, Stephen E.; Braun, Scott A.; Chiu, Christine; Wang, Jian-Jian

    2002-01-01

    Passive and active microwave remote sensing data are analyzed to identify signatures of precipitation and vertical motion in tropical convection. A database of cloud/radiative model simulations is used to quantify surface rain rates and latent heating profiles that are consistent with these signatures. At satellite footprint-scale (approximately 10 km), rain rate and latent heating estimates are subject to significant random errors, but by averaging the estimates in space and time, random errors are substantially reduced, Bias errors have been minimized by improving the microphysics in the supporting cloud/radiative model simulations, and by imposing a consistent definition of remotely-sensed and model-simulated convective/stratiform rain coverage. Remotely-sensed precipitation and latent heating distributions in the tropics are derived from Tropical Rainfall Measuring Mission (TRMM) and Special Sensor Microwave/ Imager (SSM/ I) sensor data. The prototype Version 6 TRMM passive microwave algorithm typically yields average heating profiles with maxima between 6 and 7 km altitude for organized mesoscale convective systems. Retrieved heating profiles for individual convective systems are compared to coincident estimates based upon a combination of dual-Doppler radar and rawinsonde data. Also, large-scale latent heating distributions are compared to estimates derived from a simpler technique that utilizes observations of surface rain rate and stratiform rain proportion to infer vertical heating structure. Results of these tests will be presented at the conference.

  15. EFFECTS OF AMBIENT TEMPERATURE AND EXPOSURE TO 2450-MHZ MICROWAVE RADIATION ON EVAPORATIVE HEAT LOSS IN THE MOUSE

    EPA Science Inventory

    Whole-body evaporative heat loss was measured as whole-body evaporative water loss in mice during a 90 min exposure to 2450-MHz microwave radiation at an ambient temperature of 20 C and in non-exposed mice maintained at ambient temperature of 0, 25, 30, 33, and 35 C. The ambient-...

  16. Survival of Listeria monocytogenes and Salmonella spp. on catfish exposed to microwave heating in a continuous mode

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microwave (MW) heating using continuous output may provide better and consistent cooking for foods. Currently, household units with a build-in inverter device are available in which the output is continuous vs. the traditional on-off mode. With an inverter, these MW ovens may provide consistent he...

  17. Feasibility study of microwave electron heating on the C-2 field-reversed configuration device

    NASA Astrophysics Data System (ADS)

    Yang, Xiaokang; Koehn, Alf; Petrov, Yuri; Ceccherini, Francesco; Dettrick, Sean; Binderbauer, Michl

    2015-12-01

    Different microwave heating scenarios for the C-2 plasmas have been investigated recently with use of both the Genray ray-racing code and the IPF-FDMC full-wave code, and the study was focused on the excitation of the electron Bernstein wave (EBW) with O-mode launch. For a given antenna position on C-2 and the fixed 2D plasma density and equilibrium field profiles, simulations have been done for six selected frequencies (2.45 GHz, 5 GHz, 8 GHz, 18 GHz, 28 GHz, and 50 GHz). Launch angles have been optimized for each case in order to achieve high coupling efficiencies to the EBW by the O-X-B mode conversion process and high power deposition. Results show that among those six frequencies, the case of 8 GHz is the most promising scenario, which has both high mode conversion efficiency (90%) and the relatively deeper power deposition.

  18. Continuous synthesis of monodispersed silver nanoparticles using a homogeneous heating microwave reactor system

    NASA Astrophysics Data System (ADS)

    Nishioka, Masateru; Miyakawa, Masato; Kataoka, Haruki; Koda, Hidekazu; Sato, Koichi; Suzuki, Toshishige M.

    2011-06-01

    Continuous synthesis of silver nanoparticles based on a polyol process was conducted using a microwave-assisted flow reactor installed in a cylindrical resonance cavity. Silver nitrate (AgNO3) and poly(N-vinylpyrrolidone) (PVP) dissolved in ethylene glycol were used respectively as a silver metal precursor and as a capping agent of nanoparticles. Ethylene glycol worked as the solvent and simultaneously as the reductant. Silver nanoparticles of narrow size distributions were synthesized steadily for 5 h, maintaining almost constant yield (>93%) and quality. The reaction was achieved within 2.8 s of residence time, although nanoparticles were not formed under this flow rate by conventional heating. A narrower particle size distribution was realized by the increased flow rate of the reaction solution. Nanoparticles of 9.8 nm average size with a standard deviation of 0.9 nm were synthesized at the rate of 100 ml h-l.

  19. The Role of Layer-Controlled Graphene for Tunable Microwave Heating and Its Applications to the Synthesis of Inorganic Thin Films.

    PubMed

    Kim, Kyoung Hwan; Cho, Kyeong Min; Kim, Dae Woo; Kim, Seon Joon; Choi, Jaeho; Bae, Sang Jin; Park, Sounghee; Jung, Hee-Tae

    2016-03-01

    In this paper, we present the first method for precisely controlling the heat generated by microwave heating by tuning the number of graphene layers grown by chemical vapor deposition. The conductivity of the graphene increases linearly with the number of graphene layers, indicating that Joule heating plays a primary role in the temperature control of the graphene layer. In this method, we successfully synthesize TiO2 and MoS2 thin films, which do not interact well with microwaves, on a layer-controlled graphene substrate for a very short time (3 min) through microwave heating. PMID:26836443

  20. Microwave heating of fluid/solid layers: A study of hydrodynamic stability and melting front propagation

    NASA Astrophysics Data System (ADS)

    Gilchrist, John Joseph

    In this work we study the effects of externally induced heating on the dynamics of fluid layers, and materials composed of two phases separated by a thermally driven moving front. One novel aspect of our study, is in the nature of the external source which is provided by the action of microwaves acting on dielectric materials. The main challenge is to model and solve systems of differential equations which couple fluid dynamical motions (the Navier-Stokes equations for non-isothermal flows) and electromagnetic wave propagation (governed by Maxwell's equations). When an electromagnetic wave impinges on a material, energy is generated within the material due to dipolar and ohmic heating. In the first part of the thesis, we consider hydrodynamic instabilities of such systems with particular emphasis on conditions for onset of convection. This is achieved by solving the linear stability equations in order to identify parameter values which produce instability. The analysis and subsequent numerical solutions are carried out both for materials with constant dielectric attributes (in such cases the electric field equations decouple and they can be solved in closed form), and materials with temperature dependent conductivities, dielectric permittivities and dielectric loss factors. In the latter case we incorporate known data for water or ethanol into our numerical solutions. Our solutions provide a complete picture of onset conditions as a function of input power levels and microwave frequency (or equivalently fluid layer thickness). In addition, in the case of water, the flow is found to be more stable for constant attributes as compared with temperature dependent attributes; that is, a higher power is required to set the fluid layer into convective motions in the latter case. We have also established that onset is obtained at power levels well below those needed to cause thermal runaway and consequently boiling of the water layer, for instance. Our results also identify

  1. The effect of microwave power and heating time pretreatment on biogas production from fresh and dried water hyacinth (Eichhornia crassipes)

    NASA Astrophysics Data System (ADS)

    Sumardiono, Siswo; Budiyono, Mardiani, Dini Tri

    2015-12-01

    The objective of this research was to study the effect of microwave pretreatment of fresh and dried water hyacinth on biogas production. The variations of microwave power levels are 240; 400; 560 and 800 W. The variations of microwave heating time are 5; 7 and 9 min. The unpretreated fresh and dried water hyacinth are used as control. The result of research showed that almost all pretreated water hyacinth produced biogas were higher compare tounpretreated water hyacinth. The maximum of biogas production from fresh and dried water hyacinthwere obtained at 560 W for 7 min and 400 W for 7 min of microwave pretreatment. In this condition, pretreated fresh and dried water hyacinth resulted biogas production of 75,12 and 53,06 mL/g TS, respectively. The unpretreated fresh and dried water hyacinth produced biogas of 37,56 and 33,56 mL/g TS, respectively. The microwave pretreatment of water hyacinth improved biogas production. Microwave pretreatment had a positive impact on anaerobic biodegradability of water hyacinth.

  2. Optimization of microwave heating in an existing cubicle cavity by incorporating additional wave guide and control components

    SciTech Connect

    Erle, R.R.; Eschen, V.G.; Sprenger, G.S.

    1995-04-01

    The use of microwave energy to thermally treat Low Level (LLW), Transuranic (TRU), and mixed waste has been under development at the Rocky Flats Environmental Technology Site (Site) since 1986. During that time, the technology has progressed from bench-scale tests, through pilot-scale tests, and finally to a full-scale demonstration unit. Experimental operations have been conducted on a variety of non-radioactive surrogates and actual radioactive waste forms. Through these studies and development efforts, the Microwave Vitrification Engineering Team (MVET) at Rocky Flats has successfully proven the application of microwave energy for waste treatment operations. In the microwave solidification process, microwave energy is used to heat a mixture of waste and glass frit to produce a vitrified product that meets all the current acceptance criteria at the final disposal sites. All of the development to date has utilized a multi-mode microwave system to provide the energy to treat the materials. Currently, evaluations are underway on modifications to the full-scale demonstration system that provide a single-mode operation as a possible method to optimize the system. This poster presentation describes the modifications made to allow the single-mode operation.

  3. No Major Differences Found between the Effects of Microwave-Based and Conventional Heat Treatment Methods on Two Different Liquid Foods

    PubMed Central

    Géczi, Gábor; Horváth, Márk; Kaszab, Tímea; Alemany, Gonzalo Garnacho

    2013-01-01

    Extension of shelf life and preservation of products are both very important for the food industry. However, just as with other processes, speed and higher manufacturing performance are also beneficial. Although microwave heating is utilized in a number of industrial processes, there are many unanswered questions about its effects on foods. Here we analyze whether the effects of microwave heating with continuous flow are equivalent to those of traditional heat transfer methods. In our study, the effects of heating of liquid foods by conventional and continuous flow microwave heating were studied. Among other properties, we compared the stability of the liquid foods between the two heat treatments. Our goal was to determine whether the continuous flow microwave heating and the conventional heating methods have the same effects on the liquid foods, and, therefore, whether microwave heat treatment can effectively replace conventional heat treatments. We have compared the colour, separation phenomena of the samples treated by different methods. For milk, we also monitored the total viable cell count, for orange juice, vitamin C contents in addition to the taste of the product by sensory analysis. The majority of the results indicate that the circulating coil microwave method used here is equivalent to the conventional heating method based on thermal conduction and convection. However, some results in the analysis of the milk samples show clear differences between heat transfer methods. According to our results, the colour parameters (lightness, red-green and blue-yellow values) of the microwave treated samples differed not only from the untreated control, but also from the traditional heat treated samples. The differences are visually undetectable, however, they become evident through analytical measurement with spectrophotometer. This finding suggests that besides thermal effects, microwave-based food treatment can alter product properties in other ways as well. PMID

  4. Chlorophylls and carotenoids of kiwifruit puree are affected similarly or less by microwave than by conventional heat processing and storage.

    PubMed

    Benlloch-Tinoco, María; Kaulmann, Anouk; Corte-Real, Joana; Rodrigo, Dolores; Martínez-Navarrete, Nuria; Bohn, Torsten

    2015-11-15

    The impact of microwave (1000 W - 340 s) and conventional heat (97 °C - 30s) pasteurisation and storage (4, 10, 22 °C for up to 63 d) on total and individual carotenoids and chlorophylls in kiwifruit puree was evaluated. Bioaccessibility of carotenoids, before and after pasteurisation and storage, was also studied. Microwaves and conventional heating led to marked changes in the chlorophyll (42-100% losses) and carotenoid (62-91% losses) content. First- and second-order kinetics appropriately explained the degradation of total carotenoids and chlorophylls over time, respectively. Pasteurised samples showed significantly (p < 0.05) enhanced stability of these pigments, with microwaves (k = 0.007-0.031100 g mg(-1) day(-1) at 4-22 °C) promoting chlorophyll stability to a greater extent than conventional heating (k = 0.0015-0.034100 g mg(-1) day(-1) at 4-22 °C). Bioaccessibility of carotenoids remained (p < 0.05) unaffected by processing and storage. These results highlighted that the pigment composition of microwaved kiwifruit was more similar to that of the fresh fruit and better preserved during storage. PMID:25977024

  5. Microwave blanching and drying characteristics of Centella asiatica (L.) urban leaves using tray and heat pump-assisted dehumidified drying.

    PubMed

    Trirattanapikul, W; Phoungchandang, S

    2014-12-01

    The appropriate stage of maturity of Centella asiatica (L.) Urban leaves was investigated. Mature leaves with large diameter contained high total phenolics and % inhibition. Microwave blanching for 30 s retained the highest total phenolics and the microwave blanching for 30 s and 45 s retained the highest % inhibition. Modified Henderson and Modified Chung-Pfost models showed the best fit to both fresh and blanched leaves for equilibrium moisture content, Xe = f(RHe, T) and equilibrium relative humidity, RHe = f(Xe, T), respectively. The Modified Page model was the most effective model in describing the leaf drying. All drying was in the falling rate period. The drying constant was related to drying air temperature using the Arrhenius model. Effective moisture diffusivities increased with increasing temperature and blanching treatments as well as dehumidification by heat pump-assisted dehumidified dryer. The heat pump-assited dehumidified drying incorporated by the microwave blanching could reduce the drying time at 40 °C by 31.2 % and increase % inhibition by 6.1 %. Quality evaluation by total phenolics, % inhibition and rehydration ratio showed the best quality for C. asiatica leaves pretreated by microwave blanching and dried at 40 °C in heat pump-assisted dehumidified dryer. PMID:25477629

  6. Exciting Alfven Waves using Modulated Electron Heating by High Power Microwaves

    NASA Astrophysics Data System (ADS)

    Wang, Yuhou; Gekelman, Walter; Pribyl, Patrick; van Compernolle, Bart; Papadopoulos, Konstantinos

    2014-10-01

    Experiments exploring the physics of ionospheric modification with intense perpendicular propagating waves (k-> ⊥B->0) on the Large Plasma Device (LaPD) at UCLA have been upgraded with the addition of a high power rapidly pulsed microwave source. The plasma is irradiated with ten pulses (250 kW X-band) near the upper-hybrid frequency. The pulses are modulated at a frequency of a fraction (0.1-1.0) of fci (ion cyclotron frequency). Based on a previous single-pulse experiment, the modulated electron heating may drive a large amplitude shear Alfvén wave (f heating methods involving X-mode, O-mode, and electron Bernstein mode are investigated in plasmas with controllable parameters (ne =108 ~1012 cm-3 ,Te = 0 . 1 ~ 6 eV ,Ti <

  7. Experimental Evaluation of the Heat Sink Effect in Hepatic Microwave Ablation

    PubMed Central

    Ringe, Kristina I.; Lutat, Carolin; Rieder, Christian; Schenk, Andrea; Wacker, Frank; Raatschen, Hans-Juergen

    2015-01-01

    Purpose To demonstrate and quantify the heat sink effect in hepatic microwave ablation (MWA) in a standardized ex vivo model, and to analyze the influence of vessel distance and blood flow on lesion volume and shape. Materials and Methods 108 ex vivo MWA procedures were performed in freshly harvested pig livers. Antennas were inserted parallel to non-perfused and perfused (700,1400 ml/min) glass tubes (diameter 5mm) at different distances (10, 15, 20mm). Ablation zones (radius, area) were analyzed and compared (Kruskal-Wallis Test, Dunn’s multiple comparison Test). Temperature changes adjacent to the tubes were measured throughout the ablation cycle. Results Maximum temperature decreased significantly with increasing flow and distance (p<0.05). Compared to non-perfused tubes, ablation zones were significantly deformed by perfused tubes within 15mm distance to the antenna (p<0.05). At a flow rate of 700ml/min ablation zone radius was reduced to 37.2% and 80.1% at 10 and 15mm tube distance, respectively; ablation zone area was reduced to 50.5% and 89.7%, respectively. Conclusion Significant changes of ablation zones were demonstrated in a pig liver model. Considerable heat sink effect was observed within a diameter of 15mm around simulated vessels, dependent on flow rate. This has to be taken into account when ablating liver lesions close to vessels. PMID:26222431

  8. Preparation of modified semi-coke by microwave heating and adsorption kinetics of methylene blue.

    PubMed

    Wang, Xin; Peng, Jin-Hui; Duan, Xin-Hui; Srinivasakannan, Chandrasekar

    2013-01-01

    Preparation of modified semi-coke has been achieved, using phosphoric acid as the modifying agent, by microwave heating from virgin semi-coke. Process optimization using a Central Composite Design (CCD) design of Response Surface Methodology (RSM) technique for the preparation of modifies semi-coke is presented in this paper. The optimum conditions for producing modified semi-coke were: concentration of phosphoric acid 2.04, heating time 20 minutes and temperature 587 degrees C, with the optimum iodine of 862 mg/g and yield of 47.48%. The textural characteristics of modified semi-coke were analyzed using scanning electron microscopy (SEM) and nitrogen adsorption isotherm. The BET surface area of modified semi-coke was estimated to be 989.60 m2/g, with the pore volume of 0.74 cm3/g and a pore diameter of 3.009 nm, with micro-pore volume contributing to 62.44%. The Methylene Blue monolayer adsorption capacity was found to be mg/g at K. The adsorption capacity of the modified semi-coke highlights its suitability for liquid phase adsorption application with a potential usage in waste water treatment. PMID:24779145

  9. Below and above boiling point comparison of microwave irradiation and conductive heating for municipal sludge digestion under identical heating/cooling profiles.

    PubMed

    Hosseini Koupaie, E; Eskicioglu, C

    2015-01-01

    This research provides a comprehensive comparison between microwave (MW) and conductive heating (CH) sludge pretreatments under identical heating/cooling profiles at below and above boiling point temperatures. Previous comparison studies were constrained to an uncontrolled or a single heating rate due to lack of a CH equipment simulating MW under identical thermal profiles. In this research, a novel custom-built pressure-sealed vessel which could simulate MW pretreatment under identical heating/cooling profiles was used for CH pretreatment. No statistically significant difference was proven between MW and CH pretreatments in terms of sludge solubilization, anaerobic biogas yield and organics biodegradation rate (p-value>0.05), while statistically significant effects of temperature and heating rate were observed (p-value<0.05). These results explain the contradictory results of previous studies in which only the final temperature (not heating/cooling rates) was controlled. PMID:25863200

  10. Dual-mode antenna design for microwave heating and noninvasive thermometry of superficial tissue disease.

    PubMed

    Jacobsen, S; Stauffer, P R; Neuman, D G

    2000-11-01

    Hyperthermia therapy of superficial skin disease has proven clinically useful, but current heating equipment is somewhat clumsy and technically inadequate for many patients. The present effort describes a dual-purpose, conformal microwave applicator that is fabricated from thin, flexible, multilayer printed circuit board (PCB) material to facilitate heating of surface areas overlaying contoured anatomy. Preliminary studies document the feasibility of combining Archimedean spiral microstrip antennas, located concentrically within the central region of square dual concentric conductor (DCC) annular slot antennas. The motivation is to achieve homogeneous tissue heating simultaneously with noninvasive thermometry by radiometric sensing of blackbody radiation from the target tissue under the applicator. Results demonstrate that the two antennas have complimentary regions of influence. The DCC ring antenna structure produces a peripherally enhanced power deposition pattern with peaks in the outer corners of the aperture and a broad minimum around 50% of maximum centrally. In contrast, the Archimedean spiral radiates (or receives) energy predominantly along the boresight axis of the spiral, thus confining the region of influence to tissue located within the central broad minimum of the DCC pattern. Analysis of the temperature-dependent radiometer signal (brightness temperature) showed linear correlation of radiometer output with test load temperature using either the spiral or DCC structure as the receive antenna. The radiometric performance of the broadband Archimedean antenna was superior compared to the DCC, providing improved temperature resolution (0.1 degree C-0.2 degree C) and signal sensitivity (0.3 degree C-0.8 degree C/degree C) at all four 500 MHz integration bandwidths tested within the frequency range from 1.2 to 3.0 GHz. PMID:11077744

  11. Microwave Heating and Pre-sintering of Copper Powder Metal Compacts in Separated Electric and Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Martin, Kelly; Johnson, Earnie; Ma, Junkun; Miskovsky, Nicholas; Weisel, Gary; Weiss, Brock; Zimmerman, Darin

    2006-03-01

    We present results of microwave heating and pre-sintering of pure copper metal powder compacts. Using a 2.45GHz, WR284 microwave system operating in TE102 single mode resonance, we have systematically studied the microwave heating and pre-sintering behavior of various copper powder metal compacts as a function of particle size and green density. Cylindrical samples (0.25in by 0.25in) were positioned in either the magnetic-- or electric--field antinode, allowing the study of the separate effects of the two fields. The results show significant differences in heating rates and sample microstructure (SEM) even when average sample temperatures are below half the melting point of bulk copper. Numerical simulations of the absorption and heating have been developed to check the consistency of the experimental results. We acknowledge the additional work of undergraduate students John Diehl, John Rea, Charles Smith, and Devin Spratt, who assisted in the setup of experimental apparatus, sample preparation, and data acquisition.

  12. Laboratory convection experiments with internal, noncontact, microwave generated heating, applied to Earth's mantle dynamics

    NASA Astrophysics Data System (ADS)

    Limare, Angela; Surducan, Emanoil; di Giuseppe, Erika; Surducan, Vasile; Neamtu, Camelia; Vilella, Kenny; Fourel, Loic; Farnetani, Cinzia; Kaminski, Edouard; Jaupart, Claude

    2014-05-01

    The thermal evolution of terrestrial planets is controlled by secular cooling and internal heating due to the decay of radiogenic isotopes, two processes which are equivalent from the standpoint of convection dynamics. Few studies have been devoted to the intrinsic characteristics of this form of convection, which are dominated by instabilities of a single boundary layer and which involve a non-isentropic interior thermal structure. Laboratory studies of such convection have been plagued by considerable technical difficulties and have been mostly restricted to aqueous solutions with moderate values of the Prandtl number, contrary to planetary mantles. Here, we describe a new laboratory setup to generate internal heating in controlled conditions based on microwave (MW) absorption. The advantages of our technique include, but are not limited to: (1) a volumetric heat source that can be localized or distributed in space, (2) selectively heating part of the volume with time varying intensity and space distribution. Our tank prototype had horizontal dimensions of 30 cm × 30 cm and 5 cm height. A uniform and constant temperature was maintained at the upper boundary by an aluminium heat exchanger and adiabatic conditions were imposed at the tank base. Experimental fluids were hydroxyethylcellulose - water mixtures whose viscosities were varied within a wide range depending on concentration. Experimental Prandtl numbers were set at values larger than 100. Thermochromic Liquid Crystals (TLC) were used to visualize the temperature field, and the velocity field was determined using Particle Image Velocimetry (PIV). The Rayleigh-Roberts number was varied from 105 to 107. We also conducted numerical simulations in 3D cartesian geometry using Stag-3D (Tackley 1993) to reproduce the experimental conditions, including the tank aspect ratio and the temperature dependence of physical properties. We observed that convection is driven by cold descending plumes generated at the upper

  13. Dual-slot antennas for microwave tissue heating: Parametric design analysis and experimental validation

    PubMed Central

    Brace, Christopher L.

    2011-01-01

    Purpose: Design and validate an efficient dual-slot coaxial microwave ablation antenna that produces an approximately spherical heating pattern to match the shape of most abdominal and pulmonary tumor targets.Methods: A dual-slot antenna geometry was utilized for this study. Permutations of the antenna geometry using proximal and distal slot widths from 1 to 10 mm separated by 1–20 mm were analyzed using finite-element electromagnetic simulations. From this series, the most optimal antenna geometry was selected using a two-term sigmoidal objective function to minimize antenna reflection coefficient and maximize the diameter-to-length aspect ratio of heat generation. Sensitivities to variations in tissue properties and insertion depth were also evaluated in numerical models. The most optimal dual-slot geometry of the parametric analysis was then fabricated from semirigid coaxial cable. Antenna reflection coefficients at various insertion depths were recorded in ex vivo bovine livers and compared to numerical results. Ablation zones were then created by applying 50 W for 2–10 min in simulations and ex vivo livers. Mean zone diameter, length, aspect ratio, and reflection coefficients before and after heating were then compared to a conventional monopole antenna using ANOVA with post-hoc t-tests. Statistical significance was indicated for P < 0.05.Results: Antenna performance was highly sensitive to dual-slot geometry. The best-performing designs utilized a proximal slot width of 1 mm, distal slot width of 4 mm ± 1 mm and separation of 8 mm ± 1 mm. These designs were characterized by an active choking mechanism that focused heating to the distal tip of the antenna. A dual-band resonance was observed in the most optimal design, with a minimum reflection coefficient of −20.9 dB at 2.45 and 1.25 GHz. Total operating bandwidth was greater than 1 GHz, but the desired heating pattern was achieved only near 2.45 GHz. As a result, antenna performance was

  14. Survival of Listeria monocytogenes, E.coli 0157:H7 and Salmonella spp. on catfish fillets exposed to microwave heating in a continuous mode

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microwave (MW) heating using continuous power output with feedback control and a modified ingredient formulation, may provide better and consistent cooking of foods. Currently, household units with build-in inverter power supply units are available. These new generation microwave ovens provide con...

  15. Microwave radiation as heating method in the synthesis of titanium dioxide nanoparticles from hexafluorotitanate-organic salts

    SciTech Connect

    Estruga, Marc; Domingo, Concepcion; Ayllon, Jose A.

    2010-09-15

    Nanocrystalline anatase was obtained from ionic liquid-like precursors containing hexafluorotitanate-organic salts and less than 25 wt.% of water, and using boric acid as fluoride scavenger. Two alternative heating methods were explored using either a conventional oven or a domestic microwave apparatus. A significant reduction in the reaction time from 24 h to only few minutes was obtained using the microwave route. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, nitrogen sorption analysis, and attenuated total reflectance Fourier transformed infrared, X-ray photoelectronic and Raman spectroscopes. The convenience of using the microwave heating option was a function of the organic cation present in the precursor. Thus, organic ammonium cations containing only hydrocarbon substituents, such as diethylammonium, phenylammonium and benzyltrimethylammonium led to the precipitation of nanocrystalline anatase powder with high specific surface area (up to 120 m{sup 2} g{sup -1}) in a short processing time (1-3 min). Otherwise, alcohol and carboxylate functionalized cations decomposed under microwave treatment. Moreover, the choice of the organic cation allowed tuning several properties of the end material, such as particle size and pore morphology.

  16. [Fatty acids profile and microstructure of avocado puree after microwave heating].

    PubMed

    Guzmán-Gerónimo, Rosa I; Dorantes, Lidia

    2008-09-01

    Changes in the fatty acid profile and the microstructure of avocado puree after microwave treatment were evaluated. The main components of the fatty acid profile were oleic, palmitic, linoleic and palmitoleic acids. Fatty acids profile of microwaved avocado puree did not show significant changes (p < 0.05). Trans fatty acids were not detected. Microwaved avocado puree showed significant changes in its microstructure. Samples treated with microwaves for less than 40 s preserved the cells shape, causing only a minimal modification. On the other hand, microwave treated avocado puree using more than 40 s, showed a disruption of idioblast oil cells, releasing the oil contained on them. The results might be explained based on the sensory evaluation that was performed on the microwaved avocado puree, where samples at 60 s showed oily texture and grassy flavor. PMID:19137994

  17. The ultra-rapid synthesis of 2D graphitic carbon nitride nanosheets via direct microwave heating for field emission.

    PubMed

    Yu, Yongzhi; Zhou, Qing; Wang, Jigang

    2016-02-16

    The 2D g-C3N4 nanosheets were ultra-rapidly prepared via a direct microwave heating approach. The as-synthesized g-C3N4 possessed a large surface area, few stacking layers, a large aspect ratio and an enlarged bandgap. As a consequence, the excellent field emission properties of 2D g-C3N4 nanosheets were exhibited with extremely low turn-on fields. PMID:26879135

  18. Microwave heating synthesis and formation mechanism of chalcopyrite structured CuInS{sub 2} nanorods in deep eutectic solvent

    SciTech Connect

    Zhang, Jianjun Chen, Jun; Li, Qiang

    2015-03-15

    Graphical abstract: Chalcopyrite structured CuInS{sub 2} nanorods were synthesized by an environmentally friendly microwave heating method in deep eutectic solvent. Results show that microwave heating time plays an important role in the formation of CuInS{sub 2} nanostructure phase. The SEM results indicated that the obtained CuInS{sub 2} nanostructures display rod-like morphology with diameters of about 40 nm and lengths of about 400 nm. The UV–vis spectrum results indicated that the CuInS{sub 2} nanorods exhibit strong absorption from the entire visible light region to the near-infrared region beyond 1100 nm. The possible growth mechanism of CuInS{sub 2} nanorods was discussed. - Abstract: Chalcopyrite structured CuInS{sub 2} nanorods were synthesized by an environmentally friendly microwave heating method in deep eutectic solvent. The as-synthesized CuInS{sub 2} nanorods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The results indicated that the obtained CuInS{sub 2} nanostructures display rod-like morphology with diameters of about 40 nm and lengths of about 400 nm. The influences of microwave heating time on the formation of CuInS{sub 2} phase were discussed. Ultraviolet–visible (UV–vis) and photoluminescence (PL) spectra were utilized to investigate the optical properties of CuInS{sub 2} nanorods. The results showed that the as-synthesized CuInS{sub 2} nanorods exhibit strong absorption from the entire visible light region to the near-infrared region beyond 1100 nm. PL spectrum of the as-synthesized CuInS{sub 2} nanorods displays an emission peak centered at 580 nm under excitation wavelength of 366 nm at room temperature. The possible growth mechanism of CuInS{sub 2} nanorods was discussed.

  19. Room-temperature magnetic properties of SiC based nanowires synthesized via microwave heating method

    NASA Astrophysics Data System (ADS)

    Liu, Song; Wang, Jigang

    2016-07-01

    Two kinds of ferromagnetic SiC based nanowires with and without Ni catalyst were successfully synthesized by employing microwave heating method. The comprehensive characterizations and vibrating sample magnetometer (VSM) have been applied to investigate the micro-structures and magnetic properties of as-grown nanowires. For the nanowires synthesized without using Ni catalyst, the diameters and lengths are in the range of 20-60 nm and dozens of micrometers, respectively. Particularly, the results of transmission electron microscopy (TEM) show that the nanowires consist of SiC core and SiOx shell. The SiC/SiOx coaxial nanowires exhibit room-temperature ferromagnetism with saturation magnetization (Ms) of 0.2 emu/g. As to the nanowires obtained using Ni catalyst, the scanning electron microscopy (SEM) results indicate that the Ni catalyzed nanowires have a nano-particle attached on the tip and a uniform diameter of approximately 50 nm. The vapor-liquid-solid (VLS) growth mechanism can be used to explain the formation of the Ni catalyzed nanowires. The detection result of VSM indicates that the Ni catalyzed nanowires possess the paramagnetism and the ferromagnetism, simultaneously. The enhancement of the ferromagnetism, compared with the SiC/SiOx coaxial nanowires, could be attributed to the Ni2Si and NiSi phases.

  20. Feasibility study of microwave electron heating on the C-2 field-reversed configuration device

    SciTech Connect

    Yang, Xiaokang Ceccherini, Francesco; Dettrick, Sean; Binderbauer, Michl; Koehn, Alf; Petrov, Yuri

    2015-12-10

    Different microwave heating scenarios for the C-2 plasmas have been investigated recently with use of both the Genray ray-racing code and the IPF-FDMC full-wave code, and the study was focused on the excitation of the electron Bernstein wave (EBW) with O-mode launch. For a given antenna position on C-2 and the fixed 2D plasma density and equilibrium field profiles, simulations have been done for six selected frequencies (2.45 GHz, 5 GHz, 8 GHz, 18 GHz, 28 GHz, and 50 GHz). Launch angles have been optimized for each case in order to achieve high coupling efficiencies to the EBW by the O-X-B mode conversion process and high power deposition. Results show that among those six frequencies, the case of 8 GHz is the most promising scenario, which has both high mode conversion efficiency (90%) and the relatively deeper power deposition.

  1. Influence of spike lavender (Lavandula latifolia Med.) essential oil in the quality, stability and composition of soybean oil during microwave heating.

    PubMed

    Rodrigues, Nuno; Malheiro, Ricardo; Casal, Susana; Asensio-S-Manzanera, M Carmen; Bento, Albino; Pereira, José Alberto

    2012-08-01

    Lipids oxidation is one of the main factors leading to quality losses in foods. Its prevention or delay could be obtained by the addition of antioxidants. In this sense the present work intend to monitor the protective effects of Lavandula latifolia essential oil during soybean oil microwave heating. To achieve the proposed goal quality parameters (free acidity, peroxide value, specific coefficients of extinction and ΔK), fatty acids profile, tocopherols and tocotrienols composition, antioxidant activity and oxidative stability were evaluated in soybean oil with and without spike lavender essential oils (EO) submitted to different microwave heating exposure times (1, 3, 5, 10 and 15 min; 1000 Watt) with a standard domestic microwave equipment. Microwave heating induced severe quality and composition losses, mainly above 3 min of microwave heating, regardless the sample tested. However, spike lavender EO addition counteracts the oxidation comparatively to control oils, by presenting enhanced values in quality parameters. A higher protection in unsaturated fatty acids loss was also observed as well as a higher antioxidant activity and oxidative stability. The microwave heating effects were clearly different in the samples with essential oils addition, allowing discrimination from plain soybean oils by a principal component analysis, being also capable to discriminate the different heating times tested within each sample. PMID:22659463

  2. High-power microwave transmission systems for electron-cyclotron-resonance plasma heating

    SciTech Connect

    Vernon, R.J.

    1991-08-01

    This progress report is for the sixth year of a grant from the US Department of Energy for the design, development, and fabrication of ECRH transmission and mode conversion systems to transport microwave power from a gyrotron to a magnetically confined plasma. The design and low-power testing of new and improved components for such systems and development of underlying theory is the focus of this project. Devising and improving component testing and diagnostic techniques is also an important part of this effort. The development of possible designs for sections of gyrotrons themselves, such as tapers or Vlasov-type launchers, in support of the Varian gyrotron development program is also considered when appropriate. We also provide support to other groups working on ECR heating of magnetically confined plasmas such as the groups at General Atomics, the University of Texas at Austin, and Lawrence Livermore National Laboratory. During the last year, we designed and had fabricated a two-dimensional Vlasov antenna system for a 110 GHz TE{sub 15,2} mode gyrotron for possible use at General Atomics. The system included the launcher section, a visor, main reflector, and focusing reflector. Programs to generate the tool-path profiles to cut the General Atomics'' Vlasov components on a milling machine were developed. We have also developed state-of-the art theory and programs for three-dimensional whispering-gallery-mode Vlasov antenna systems. A design for a 110 GHz TE{sub 01}-TE{sub 15,2} mode converter system for cold testing WGM Vlasov antenna systems was developed and is currently being fabricated also.

  3. New Perspectives on Longwave Imaging of Urban Heat Islands: Middle Infrared to Microwaves

    NASA Astrophysics Data System (ADS)

    Henebry, G. M.; Krehbiel, C. P.; Zheng, B.; Nguyen, L. H.; de Beurs, K.; Owsley, B.

    2015-12-01

    Urban populations are projected to increase throughout the century. As urban areas expand and increase in density as a result of population pressures, urban heat islands (UHIs) will grow and intensify. Characterization of UHIs using remote sensing has focused primarily on the use of thermal infrared (TIR) sensors. Remote sensing of TIR measures, at 1 km spatial resolution or coarser, land surface or skin temperatures to reveal the surface UHI (sUHI) in contrast to in situ approaches that measure air temperature at points in networks or along transects. The city, its suburbs, and rural matrix all emit longwave electromagnetic radiation at wavelengths both shorter and longer than TIR. Here we introduce the use of two other wavelength regions for UHI characterization. Our prior work has shown that the middle infrared (MIR) in the atmospheric window from 3-5 microns offers some advantages to imaging urban areas. We demonstrate a new method for characterizing the intensity and the seasonality of sUHI in the MIR for selected cities in North America and Europe using MODIS band 23. In contrast to MIR and TIR sensors, microwave radiometers (MWR) can retrieve both air temperature and water vapor, albeit at coarse spatial resolution (~25 km) relative to most urban areas. Using the AMSR-E/AMSR2 product time series, we show both the advantages and limitations of using MWR data to characterize UHIs in the megacities and major conurbations of North and South America. These new approaches to UHI characterization complement the traditional TIR methods to reveal other impacts of cities on their environment.

  4. Rapid iron borate (FeBO3) powder fabrication using microwave heating

    NASA Astrophysics Data System (ADS)

    Yang, Chia-En; Cheng, Jiping; Yin, Shizhuo

    2010-08-01

    Microwave assisted synthesis of crystalline FeBO3 powder is investigated in a multimode cavity at 2.45GHz as a possible method for faster synthesis. An Alumina-SiC susceptor enclosure was placed inside the cavity to overcome poor microwave absorption of the precursor at low temperatures. Enhanced diffusion was observed with appropriate precursor viscosity at reaction temperature. Less than 8 hours was found enough to complete FeBO3 synthesis, as compared with more than 20 hours of synthesis using conventional muffle oven. Microwave enhanced diffusion was not obvious with too high viscosity and eventually leveled by thermal diffusion with too low viscosity. The microwave synthesized FeBO3 particles were found more rhombohedral and smaller than conventional furnace synthesized ones, thus are inherently more suitable as optical composite materials.

  5. Abnormal electron-heating mode and formation of secondary-energetic electrons in pulsed microwave-frequency atmospheric microplasmas

    SciTech Connect

    Kwon, H. C.; Jung, S. Y.; Kim, H. Y.; Won, I. H.; Lee, J. K.

    2014-03-15

    The formation of secondary energetic electrons induced by an abnormal electron-heating mode in pulsed microwave-frequency atmospheric microplasmas was investigated using particle-in-cell simulation. We found that additional high electron heating only occurs during the first period of the ignition phase after the start of a second pulse at sub-millimeter dimensions. During this period, the electrons are unable to follow the abruptly retreating sheath through diffusion alone. Thus, a self-consistent electric field is induced to drive the electrons toward the electrode. These behaviors result in an abnormal electron-heating mode that produces high-energy electrons at the electrode with energies greater than 50 eV.

  6. Structure, magnetization, specific heat, and microwave properties of K x Fe{}_{2{--}{\\text{}}y}Se2

    NASA Astrophysics Data System (ADS)

    Yazici, D.; Basaran, Ali C.; Ramírez, J. G.; Schuller, Ivan K.; Maple, M. B.

    2016-08-01

    Temperature-dependent magnetization, specific heat, and magnetic field modulated microwave spectroscopy (MFMMS) measurements were performed on single crystals of K x Fe{}2-ySe2. Magnetization measurements yield a superconducting transition temperature (T c) of ∼30 K, with a diamagnetic shielding fraction of nearly 90%. Specific heat measurements revealed a ‘jump’ at T c, {{Δ }}C/T{| }{T{{c}}}, of about 6.8 ± 1 mJ mol‑1 K‑2, consistent with bulk superconductivity in K x Fe{}2-ySe2. Moreover, MFMMS measurements detect the superconductivity of K x Fe{}2-ySe2 with a peak with an onset at {T}{{c}}μ ∼ 28 K, close to the values of T c determined from the magnetization and specific heat measurements. The presence and the shape of the low temperature MFMMS signal could be ascribed to a complex dissipation mechanism and percolative superconductivity.

  7. Microwave Pasteurization of Cooked Pasta: Effect of Process Parameters on Texture and Quality for Heat-and-Eat and Ready-to-Eat Meals.

    PubMed

    Joyner Melito, Helen S; Jones, Kari E; Rasco, Barbara A

    2016-06-01

    Pasta presents a challenge to microwave processing due to its unique cooking requirements. The objective of this study was to determine the effects of microwave processing on pasta physicochemical and mechanical properties. Fettuccine pasta was parboiled for selected times, then pasteurized using a Microwave Assisted Pasteurization System and stored under refrigeration for 1 wk. Samples were analyzed using microscopy, mechanical testing, and chemical analyses after storage. While no significant differences were observed for free amylose among fresh samples, samples parboiled for ≤6 min had significantly higher free amylose, suggesting reduced starch retrogradation. Increased heat treatment increased degree of protein polymerization, observed in microstructures as increased gluten strand thickness and network density. Firmness and extensibility increased with increased parboil time; however, extension data indicated an overall weakening of microwave-treated pasta regardless of total cooking time. Overall, microwave pasteurization was shown to be a viable cooking method for pasta. PMID:27272246

  8. A low cost technique for synthesis of gold nanoparticles using microwave heating and its application in signal amplification for detecting Escherichia Coli O157:H7 bacteria

    NASA Astrophysics Data System (ADS)

    Thanh Ngo, Vo Ke; Giang Nguyen, Dang; Phat Huynh, Trong; Lam, Quang Vinh

    2016-09-01

    In the present work a low cost technique for preparation of gold nanoparticles (AuNPs) using microwave heating was developed. The effect of different elements (precursor reagents, irradiation time, and microwave radiation power) on the final morphology of AuNPs obtained through the microwave assisted technique has been investigated. The characterization of the samples has been carried out by transmission electron microscopy, UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy, and powder x-ray diffraction. The results showed that to some extent the above-mentioned characterizations influenced the size of synthetized nanoparticles and application of microwave heating has many advantages such as low cost, rapid preparation and highly uniform particles. As an application in quartz crystal microbalance (QCM) immunosensor, AuNPs are conjugated with the Escherichia coli (E.coli) O157:H7 antibodies for signal amplification to detect E.coli O157:H7 bacteria residual in QCM system.

  9. Investigation of temporal-spatial parameters of an urban heat island on the basis of passive microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Khaikine, M. N.; Kuznetsova, I. N.; Kadygrov, E. N.; Miller, E. A.

    2006-02-01

    Quantitative measurements of the impact of an urban environment on the thermal state of the atmospheric boundary layer are presented. Temperature profiles up to the height of 600 m were obtained in a continuous series of measurements by three microwave profilers MTP-5 located in different areas of Moscow. The influence of this large city on urban heat island (UHI) parameters was estimated on occasions with stationary atmospheric processes and during cases with frontal passage. Two types of UHI were identified: one with a dome of urban warmth at all levels, and another with a low warm dome in combination with a lens of cold air above.

  10. Cashew Nut Quality as Influenced by Microwave Heating Used for Stored Grain Insect Control

    PubMed Central

    Shah, Narendra G.; Kumar, Girish

    2014-01-01

    The objective of this work is to investigate the effect of microwave power levels (240, 360, and 480 W) and exposure time (30, 60, 90, 120, 180, and 240 s) on various properties of cashew nuts being used for disinfestation. The nuts were analyzed for moisture content, temperature rise, colour, free fatty acid (FFA) and peroxide value (PV). Experiments were conducted according to the response surface methodology. Increase in microwave power level and exposure time caused a decrease in moisture content, increase in temperature, and change in colour. Microwave treatment to target temperatures of 50–55°C (unfavorable for insect survival) made the PV of cashew nut decrease to 1.10 to 1.66 meq O2/Kg (from an initial value of 2.08 ± 0.05) and FFA value to 0.11 to 0.51% (from an initial value of 0.68 ± 0.03). Though PV and FFA values of microwave treated cashew nut were found to increase after 6 months of storage at room conditions, the values were within the limits for acceptable quality. Microwave treated cashew nuts were free from infestation and rancidity even after 6 months of storage while the untreated nuts were found to be heavily infested at the end of 1 month of storage. PMID:26904638

  11. Cashew Nut Quality as Influenced by Microwave Heating Used for Stored Grain Insect Control.

    PubMed

    Das, Ipsita; Shah, Narendra G; Kumar, Girish

    2014-01-01

    The objective of this work is to investigate the effect of microwave power levels (240, 360, and 480 W) and exposure time (30, 60, 90, 120, 180, and 240 s) on various properties of cashew nuts being used for disinfestation. The nuts were analyzed for moisture content, temperature rise, colour, free fatty acid (FFA) and peroxide value (PV). Experiments were conducted according to the response surface methodology. Increase in microwave power level and exposure time caused a decrease in moisture content, increase in temperature, and change in colour. Microwave treatment to target temperatures of 50-55°C (unfavorable for insect survival) made the PV of cashew nut decrease to 1.10 to 1.66 meq O2/Kg (from an initial value of 2.08 ± 0.05) and FFA value to 0.11 to 0.51% (from an initial value of 0.68 ± 0.03). Though PV and FFA values of microwave treated cashew nut were found to increase after 6 months of storage at room conditions, the values were within the limits for acceptable quality. Microwave treated cashew nuts were free from infestation and rancidity even after 6 months of storage while the untreated nuts were found to be heavily infested at the end of 1 month of storage. PMID:26904638

  12. Application of Microwave Irradiation and Heat to Improve Gliadin Detection and Ricin ELISA Throughput with Food Samples

    PubMed Central

    Garber, Eric A. E.; Thole, Joseph

    2015-01-01

    The utility of microwave irradiation to accelerate the onset of equilibrium and improve ELISA performance was examined using ELISAs for the detection of the plant toxin ricin and gliadin. The ricin ELISA normally requires several one hour incubations at 37 °C, a total assay time of approximately five hours, and employs a complex buffer containing PBS, Tween-20®, and non-fat milk. Different energy levels and pulse designs were compared to the use of abbreviated incubation times at 37 °C for the detection of ricin in food. The use of microwave irradiation had no significant advantage over the application of heat using an oven incubator and performed worse with some foods. In contrast, a gliadin ELISA that relied on 30 min incubation steps at room temperature and a salt-based buffer performed better upon irradiation but also displayed improvement upon incubating the microtiter plate at 37 °C. Whether microwave irradiation was advantageous compared to incubation in an oven was inconclusive. However, by abbreviating the incubation time of the ricin ELISA, it was possible to cut the assay time to less than 2 hours and still display LOD values < 10 ppb and recoveries of 78%–98%. PMID:26110503

  13. Application of Microwave Irradiation and Heat to Improve Gliadin Detection and Ricin ELISA Throughput with Food Samples.

    PubMed

    Garber, Eric A E; Thole, Joseph

    2015-06-01

    The utility of microwave irradiation to accelerate the onset of equilibrium and improve ELISA performance was examined using ELISAs for the detection of the plant toxin ricin and gliadin. The ricin ELISA normally requires several one hour incubations at 37 °C, a total assay time of approximately five hours, and employs a complex buffer containing PBS, Tween-20®, and non-fat milk. Different energy levels and pulse designs were compared to the use of abbreviated incubation times at 37 °C for the detection of ricin in food. The use of microwave irradiation had no significant advantage over the application of heat using an oven incubator and performed worse with some foods. In contrast, a gliadin ELISA that relied on 30 min incubation steps at room temperature and a salt-based buffer performed better upon irradiation but also displayed improvement upon incubating the microtiter plate at 37 °C. Whether microwave irradiation was advantageous compared to incubation in an oven was inconclusive. However, by abbreviating the incubation time of the ricin ELISA, it was possible to cut the assay time to less than 2 hours and still display LOD values < 10 ppb and recoveries of 78%-98%. PMID:26110503

  14. Microwave bonding of MEMS component

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B. (Inventor); Mai, John D. (Inventor); Jackson, Henry W. (Inventor); Budraa, Nasser K. (Inventor); Pike, William T. (Inventor)

    2005-01-01

    Bonding of MEMs materials is carried out using microwave. High microwave absorbing films are placed within a microwave cavity, and excited to cause selective heating in the skin of the material. This causes heating in one place more than another. Thereby minimizing the effects of the bonding microwave energy.

  15. Microwave-specific acceleration of a Friedel-Crafts reaction: evidence for selective heating in homogeneous solution.

    PubMed

    Rosana, Michael R; Hunt, Jacob; Ferrari, Anthony; Southworth, Taylor A; Tao, Yuchuan; Stiegman, Albert E; Dudley, Gregory B

    2014-08-15

    Thermally promoted Friedel-Crafts benzylation of arene solvents has been examined under both conventional convective heating with an oil bath and heating using microwave (MW) energy. Bulk solution temperatures-as measured by internal and external temperature probes and as defined by solvent reflux-were comparable in both sets of experiments. MW-specific rate enhancements were documented under certain conditions and not others. The observed rate enhancements at a given temperature are proposed to arise from selective MW heating of polar solutes, perturbing thermal equilibrium between the solute and bulk solution. Central to MW-specific thermal phenomena is the difference between heat and temperature. Temperature is a measure of the ensemble average kinetic molecular energy of all solution components, but temperature does not provide information about solute-specific energy differences that may arise as a consequence of selective MW heating. Enhanced chemical reactivity of the MW-absorbing solute can be described as a MW-specific "extra-temperature thermal effect", because the measurable solution temperature only captures a portion of the solute kinetic molecular energy. Experimental factors that favor MW-specific rate enhancements are discussed with an eye toward future development of MW-actuated organic reactions, in which the observed thermal reactivity exceeds what is predicted from temperature-based Arrhenius calculations. PMID:25050855

  16. Correlation of Heating Rates, Crystal Structures, and Microwave Dielectric Properties of Li2ZnTi3O8 Ceramics

    NASA Astrophysics Data System (ADS)

    Lu, Xuepeng; Zheng, Yong; Huang, Qi; Xiong, Weihao

    2015-11-01

    The correlation of heating rates, crystal structures, and microwave dielectric properties of Li2ZnTi3O8 ceramics was thoroughly investigated. Ionic polarizability, atomic packing fractions, bond strengths, and octahedral distortion of Li2ZnTi3O8 ceramics were calculated on the basis of structure refinement data. The "black core" phenomenon resulting from reduction of Ti4+ ions was observed for Li2ZnTi3O8 ceramic sintered at 1°/min; reduction of Ti4+ ions could be limited by heating more rapidly. For heating rates from 1 to 7°/min, the dielectric constants ( ɛ r) of Li2ZnTi3O8 ceramics were mainly determined by ionic polarizability. The temperature coefficient of the resonant frequency ( τ f ) of Li2ZnTi3O8 ceramics was determined by bond strengths. Li2ZnTi3O8 ceramic sintered at 1°/min had the lowest quality factor ( Q × f); this was related to the high dielectric loss as a result of oxygen vacancies formed by reduction of Ti4+ ions. Q × f values of Li2ZnTi3O8 ceramics also decreased with increasing heating rate from 3 to 7°/min, owing to reduced packing fractions and average grain sizes. Li2ZnTi3O8 ceramic sintered at 3°/min had the optimum microwave dielectric properties of ɛ r = 26.6, Q × f = 83,563 GHz, and τ f = -12.4 ppm/°C.

  17. Formation of 4-aminopyrimidines via the trimerization of nitriles using focused microwave heating.

    PubMed

    Baxendale, Ian R; Ley, Steven V

    2005-01-01

    A series of substituted aliphatic nitriles have been trimerized to their corresponding pyrimidine structures under solvent-free conditions in the presence of catalytic quantities of potassium tert-butoxide using a focused microwave reactor. Multigram quantities of the corresponding 4-aminopyrimidines have been prepared in high yields and purity following a simple and scaleable protocol. PMID:15877477

  18. Sodium nitrate containing mixture for producing ceramic-glass-ceramic seal by microwave heating

    DOEpatents

    Blake, R.D.; Meek, T.T.

    1984-10-10

    A mixture for, and method of using such a mixture, for producing a ceramic-glass-ceramic seal by the use of microwave energy are disclosed, wherein the mixture comprises a glass sealing material, a coupling agent, and an oxidizer. The seal produced exhibits greater strength due to its different microstructure. Sodium nitrate is the most preferred oxidizer.

  19. Method for producing ceramic-glass-ceramic seals by microwave heating

    DOEpatents

    Blake, Rodger D.; Meek, Thomas T.

    1986-01-01

    Method for producing a ceramic-glass-ceramic seal by the use of microwave energy, and a sealing mixture which comprises a glass sealing material, a coupling agent, and an oxidizer. The seal produced exhibits greater strength due to its different microstructure. Sodium nitrate is the most preferred oxidizer.

  20. Enhanced flow injection leaching of rocks by focused microwave heating with in-line monitoring of released elements by inductively coupled plasma mass spectrometry.

    PubMed

    Silva, Milithza; Kyser, Kurt; Beauchemin, Diane

    2007-02-19

    A focused microwave digestion system was used to heat a mini-column of sample of crushed rock (hematite) during its successive leaching by repeated 250-microL injections of water, HNO(3) 1%, 10% and 30% (v/v). The mini-column was connected to the nebulizer of an inductively coupled plasma mass spectrometry instrument, which allowed a continuous monitoring of the progressive release of elements by a given leaching reagent. Quantitation of the accessible fraction of Mg, V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Sb and Pb was done by calibration using 250-microL injections of standard solutions prepared in the leaching reagent matrices. Total digestion of the sample residue was also done to verify mass balance. With the exception of Mg, V and Co, where the same total amount was released with or without microwave heating, an increased release resulted from focused microwave heating, by up to an order of magnitude. Furthermore, mass balance was verified for more elements using microwave heating, presumably because of a lower relative proportion of spectroscopic interference as a result of an increased release of analytes. Using microwave energy in general resulted in the dissolution of additional phases, as evidenced by significantly different (208)Pb/(206)Pb ratios as well as the increased release of elements with milder reagents. In fact, in the case of Pb, leaching with 30% HNO(3) was no longer necessary as all the Pb was released in the first three leaching reagents. Microwave heating could therefore be used advantageously in on-line leaching for exploration geochemistry and environmental monitoring. PMID:17386636

  1. Comparison of heat and mass transfer of different microwave-assisted extraction methods of essential oil from Citrus limon (Lisbon variety) peel.

    PubMed

    Golmakani, Mohammad-Taghi; Moayyedi, Mahsa

    2015-11-01

    Dried and fresh peels of Citrus limon were subjected to microwave-assisted hydrodistillation (MAHD) and solvent-free microwave extraction (SFME), respectively. A comparison was made between MAHD and SFME with the conventional hydrodistillation (HD) method in terms of extraction kinetic, chemical composition, and antioxidant activity. Higher yield results from higher extraction rates by microwaves and could be due to a synergy of two transfer phenomena: mass and heat acting in the same way. Gas chromatography/mass spectrometry (GC/MS) analysis did not indicate any noticeable differences between the constituents of essential oils obtained by MAHD and SFME, in comparison with HD. Antioxidant analysis of the extracted essential oils indicated that microwave irradiation did not have adverse effects on the radical scavenging activity of the extracted essential oils. The results of this study suggest that MAHD and SFME can be termed as green technologies because of their less energy requirements per ml of essential oil extraction. PMID:26788292

  2. Method and apparatus for selectively annealing heterostructures using microwave

    NASA Technical Reports Server (NTRS)

    Atwater, Harry A. (Inventor); Brain, Ruth A. (Inventor); Barmatz, Martin B. (Inventor)

    1998-01-01

    The present invention discloses a process for selectively annealing heterostructures using microwaves. A heterostructure, comprised of a material having higher microwave absorption and a material having lower microwave absorption, is exposed to microwaves in the cavity. The higher microwave absorbing material absorbs the microwaves and selectively heats while the lower microwave absorbing material absorbs small amounts of microwaves and minimally heats. The higher microwave absorbing material is thereby annealed onto the less absorbing material which is thermally isolated.

  3. Method and apparatus for selectively annealing heterostructures using microwaves

    NASA Technical Reports Server (NTRS)

    Atwater, Harry A. (Inventor); Brain, Ruth A. (Inventor); Barmatz, Martin B. (Inventor)

    1998-01-01

    The present invention discloses a process for selectively annealing heterostructures using microwaves. A heterostructure, comprised of a material having higher microwave absorption and a material having lower microwave absorption, is exposed to microwaves in the cavity. The higher microwave absorbing material absorbs the microwaves and selectively heats while the lower microwave absorbing material absorbs small amounts of microwaves and minimally heats. The higher microwave absorbing material is thereby annealed onto the less absorbing material which is thermally isolated.

  4. Characterisation of water hyacinth with microwave-heated alkali pretreatment for enhanced enzymatic digestibility and hydrogen/methane fermentation.

    PubMed

    Lin, Richen; Cheng, Jun; Song, Wenlu; Ding, Lingkan; Xie, Binfei; Zhou, Junhu; Cen, Kefa

    2015-04-01

    Microwave-heated alkali pretreatment (MAP) was investigated to improve enzymatic digestibility and H2/CH4 production from water hyacinth. SEM revealed that MAP deconstructed the lignocellulose matrix and swelled the surfaces of water hyacinth. XRD indicated that MAP decreased the crystallinity index from 16.0 to 13.0 because of cellulose amorphisation. FTIR indicated that MAP effectively destroyed the lignin structure and disrupted the crystalline cellulose to reduce crystallinity. The reducing sugar yield of 0.296 g/gTVS was achieved at optimal hydrolysis conditions (microwave temperature = 190°C, time = 10 min, and cellulase dosage = 5 wt%). The sequentially fermentative hydrogen and methane yields from water hyacinth with MAP and enzymatic hydrolysis were increased to 63.9 and 172.5 mL/gTVS, respectively. The energy conversion efficiency (40.0%) in the two-stage hydrogen and methane cogeneration was lower than that (49.5%) in the one-stage methane production (237.4 mL/gTVS) from water hyacinth with MAP and enzymatic hydrolysis. PMID:25668753

  5. Removal of Pb(II) from water by the activated carbon modified by nitric acid under microwave heating.

    PubMed

    Yao, Shuheng; Zhang, Jiajun; Shen, Dekui; Xiao, Rui; Gu, Sai; Zhao, Ming; Liang, Junyu

    2016-02-01

    The rice husk based activated carbon (RH-AC) was treated by nitric acid under microwave heating, in order to improve its capability for the removal of heavy metal ions from water. The optimal conditions for the modification of RH-AC (M-RH-AC) were determined by means of orthogonal array experimental design, giving those as the concentration of nitric acid of 8mol/L, modification time of 15min, modification temperature of 130°C and microwave power of 800W. The characteristics of the M-RH-AC and RH-AC were examined by BET, XRD, Raman spectrum, pH titration, zeta potential, Boehm titration and FTIR analysis. The M-RH-AC has lower pore surface area, smaller crystallite, lower pHIEP and more oxygen-containing functional groups than the RH-AC. Removal capacity of Pb(II) ions by the M-RH-AC and RH-AC from water solution was estimated concerning the influence of contact time, pH value, and initial concentration. The equilibrium time of Pb(II) removal was found to be around 90min after modification process. Two kinetic models are adopted to describe the possible Pb(II) adsorption mechanism, finding that the adsorption rate of Pb(II) ions by the M-RH-AC is larger than that of RH-AC. PMID:26520818

  6. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part 2; Evaluation of Estimates Using Independent Data

    NASA Technical Reports Server (NTRS)

    Yang, Song; Olson, William S.; Wang, Jian-Jian; Bell, Thomas L.; Smith, Eric A.; Kummerow, Christian D.

    2004-01-01

    Rainfall rate estimates from space-borne k&ents are generally accepted as reliable by a majority of the atmospheric science commu&y. One-of the Tropical Rainfall Measuring Mission (TRh4M) facility rain rate algorithms is based upon passive microwave observations fiom the TRMM Microwave Imager (TMI). Part I of this study describes improvements in the TMI algorithm that are required to introduce cloud latent heating and drying as additional algorithm products. Here, estimates of surface rain rate, convective proportion, and latent heating are evaluated using independent ground-based estimates and satellite products. Instantaneous, OP5resolution estimates of surface rain rate over ocean fiom the improved TMI algorithm are well correlated with independent radar estimates (r approx. 0.88 over the Tropics), but bias reduction is the most significant improvement over forerunning algorithms. The bias reduction is attributed to the greater breadth of cloud-resolving model simulations that support the improved algorithm, and the more consistent and specific convective/stratiform rain separation method utilized. The bias of monthly, 2.5 deg. -resolution estimates is similarly reduced, with comparable correlations to radar estimates. Although the amount of independent latent heating data are limited, TMI estimated latent heating profiles compare favorably with instantaneous estimates based upon dual-Doppler radar observations, and time series of surface rain rate and heating profiles are generally consistent with those derived from rawinsonde analyses. Still, some biases in profile shape are evident, and these may be resolved with: (a) additional contextual information brought to the estimation problem, and/or; (b) physically-consistent and representative databases supporting the algorithm. A model of the random error in instantaneous, 0.5 deg-resolution rain rate estimates appears to be consistent with the levels of error determined from TMI comparisons to collocated radar

  7. Behavior of microwave-heated silicon carbide particles at frequencies of 2.0–13.5 GHz

    SciTech Connect

    Sugawara, H.; Hayashi, M.; Ishihara, S.; Kashimura, K.; Mitani, T.; Shinohara, N.

    2014-07-21

    Silicon carbide is a key material in microwave (MW) processing and is used widely as a thermal insulator and catalytic agent. In this study, we experimentally investigated the temperature dependence of the MW-absorption properties of SiC particles at frequencies of 2.0–13.5 GHz. We heated SiC particles of different sizes using MW radiation. The heating behaviors of the particles were then compared with their MW-absorption properties. The heating behavior of the particles was dependent on their radii; this result was in keeping with theoretical predictions. Furthermore, the β-SiC particles exhibited anomalous behaviors when subjected to microwave heating at temperatures of 1100 °C and higher. These behaviors were attributable to the transformation of β-SiC into the α-phase. The underlying mechanism for this transformation is discussed on the basis of the results of X-ray diffraction analysis.

  8. Influence of water activity on inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in peanut butter by microwave heating.

    PubMed

    Song, Won-Jae; Kang, Dong-Hyun

    2016-12-01

    This study evaluated the efficacy of a 915 MHz microwave with 3 different electric power levels to inactivate three pathogens in peanut butter with different aw. Peanut butter inoculated with Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium and Listeria monocytogenes (0.3, 0.4, and 0.5 aw) were treated with a 915 MHz microwave with 2, 4, and 6 kW for up to 5 min. Six kW 915 MHz microwave treatment for 5 min reduced these three pathogens by 1.97 to >5.17 log CFU/g. Four kW 915 MHz microwave processing for 5 min reduced these pathogens by 0.41-1.98 log CFU/g. Two kW microwave heating did not inactivate pathogens in peanut butter. Weibull and Log-Linear + Shoulder models were used to describe the survival curves of three pathogens because they exhibited shouldering behavior. Td and T5d values were calculated based on the Weibull and Log-Linear + Shoulder models. Td values of the three pathogens were similar to D-values of Salmonella subjected to conventional heating at 90 °C but T5d values were much shorter than those of conventional heating at 90 °C. Generally, increased aw resulted in shorter T5d values of pathogens, but not shorter Td values. The results of this study can be used to optimize microwave heating pasteurization system of peanut butter. PMID:27554151

  9. Dielectric and magnetic properties of NiFe2O4 at 2.45 GHz and heating capacity for potential uses under microwaves

    NASA Astrophysics Data System (ADS)

    Polaert, Isabelle; Bastien, Samuel; Legras, Benoit; Estel, Lionel; Braidy, Nadi

    2015-01-01

    This paper presents the dielectric and magnetic properties, measured at 2.45 GHz, of a new nickel ferrite, NiFe2O4, synthetized by plasma technology. These properties were measured by the small perturbation method in a resonant cavity, from 293 to 513 K. Using these values, the adiabatic heating of nanoparticles of NiFe2O4 under microwave irradiation was also modeled. The wave propagation equation (Maxwell's equation) coupled to the heat transfer in the solid was numerically solved. The influence of parameters such as the bed volume, its porosity, the microwave incident power or the microwave system geometry is discussed. This study demonstrates that NiFe2O4 nanoparticles can be rapidly heated up to at least 513 K under microwaves and can probably achieve higher temperatures according to the thermal insulation. The magnetic contribution to heating overcomes the dielectric one in the explored temperature range. Very efficient energy yield (>90%) can then be achieved when the magnetic field position is centered over the bed.

  10. Heating characteristics of antenna arrays used in microwave ablation: A theoretical parametric study.

    PubMed

    Karampatzakis, Andreas; Kühn, Sven; Tsanidis, George; Neufeld, Esra; Samaras, Theodoros; Kuster, Niels

    2013-10-01

    A numerical study of the performance of antenna arrays used in microwave ablation (MWA) is carried out. Double-slot coaxial antennas in triangular and square configurations are studied. Clinical (healthy vs. malignant) and experimental (in vs. ex vivo) scenarios for hepatic cancer treatment are modeled, and further application in bone and lung tissue is examined. It is found that triangular arrays can create spherical ablation zones, while square configurations result in flatter ones. Thresholds in power and application times for creating continuous ablation zones are calculated, and the characteristics of the latter are quantified. PMID:24034722

  11. Effects of water washing and torrefaction pretreatments on rice husk pyrolysis by microwave heating.

    PubMed

    Zhang, Shuping; Dong, Qing; Zhang, Li; Xiong, Yuanquan; Liu, Xinzhi; Zhu, Shuguang

    2015-10-01

    The influences of water washing, torrefaction and combined water washing-torrefaction pretreatments on microwave pyrolysis of rice husk samples were investigated. The results indicated that the process of combined water washing-torrefaction pretreatment could effectively remove a large portion of inorganics and improve the fuel characteristics to a certain extent. The gas products were rich in combustible compositions and the syngas quality was improved by pretreatment process. The liquid products contained less moisture content, acids and furans, while more concentrated phenols and sugars from microwave pyrolysis of rice husk after pretreatments, especially after the combined water washing-torrefaction pretreatment. Biochar, produced in high yield, has the alkaline pH (pH 8.2-10.0) and high surface area (S(BET) 157.81-267.84 m(2)/g), they have the potential to be used as soil amendments. It is noteworthy that water washing increased the pore surface area of biochar, but torrefaction reduced the pore surface area. PMID:26159301

  12. On microstructure and flexural strength of metal-ceramic composite cladding developed through microwave heating

    NASA Astrophysics Data System (ADS)

    Sharma, Apurbba Kumar; Gupta, Dheeraj

    2012-05-01

    A domestic multimode microwave applicator was used to develop carbide reinforced (tungsten-based) metal-matrix composite cladding on austenitic stainless steel substrate. Cladding was developed through microwave irradiation of the preplaced clad materials at 2.45 GHz for 420 s. Clads show metallurgical bonding with substrate by partial dilution of materials. Back scattered images of clad section confirm uniformly distributed reinforced particles in the metallic matrix. Presence of WC, W2C, NiSi, NiW and Co3W3C phases was detected in the clad. Flexural characteristics show two distinct load transitions attributable to deformations of the matrix and the reinforced particles. Clads fail at the upper transition load; further load is taken by the SS-316 substrate. Clads exhibit good stiffness and good adhesion with the substrate. Multi directional cracks were observed at the clad surface; on further loading, cracks get propagated into the clad thickness without getting peeled-off. Mechanism of clad development has been introduced.

  13. Efficacy of Microwave-Heating during Alkaline Processing of Fumonisin-Contaminated Maize

    PubMed Central

    MENDEZ-ALBORES, Abraham; CARDENAS-RODRIGUEZ, Denisse Anelem; VAZQUEZ-DURAN, Alma

    2014-01-01

    Abstract Background Fumonisins (a family of foodborne carcinogenic mycotoxins) cause health hazards to humans and animals in developing countries, and has also economic implications. Therefore, the efficacy of a novel environmental friendly nixtamalization procedure to make tortillas (the main staple food for the Mexican population) was investigated. Methods Maize contaminated with 2136.67 ng/g total fumonisins was processed into tortillas, starting with maize grits mixed with water and calcium hydroxide that was cooked in a microwave field at 2.45 GHz during 3.75 min, and steeped 3.5 h at room temperature. The steeped maize grits (nixtamal) was stone-ground into masa (maize dough), which was then used to make tortillas. Total fumonisin content was determined using monoclonal antibody columns. Results Masa contained 1998.33 ng/g total fumonisins, which represents 6.5% toxin reduction. Nevertheless, fumonisin concentration was reduced significantly in tortillas (up to 985.33 ng/g) due to the cooking process, corresponding to a cumulative toxin degradation of 54%. Tortillas were below the maximum tolerated level, considering the European Union regulatory limit for fumonisins in maize (1000 ng/g). The physicochemical and technological properties of tortillas were also considered within the acceptable margins of quality. Conclusion Microwave nixtamalization was not a feasible method to reduce fumonisin content in masa to acceptable levels; however, an effective extra-reduction occurred when masa was baking into tortillas. PMID:26060737

  14. Switch mode power supply for microwave heating based on the Boucherot effect.

    PubMed

    Georghiou, G E; Meredith, R; Metaxas, A C; Gurwicz, D

    1999-01-01

    This paper describes a new self-resonating switch-mode power-supply for driving CW magnetrons, based on the Boucherot effect. A detailed circuit analysis is given and its performance is evaluated for an 800 W/2450 MHz magnetron, whilst work at high power driving a magnetron up to 40 kW is reported. A comparison of the supply with the conventional power-supply used in microwave ovens is made and the principal features of the new design are found to be: low energy dissipation under short-circuit conditions, low ripple current and voltage waveforms that result in more precise control in the range 20-100% of rated power, high efficiencies and small size and weight. PMID:10687152

  15. Evaluation of geophysical parameters measured by the Nimbus-7 microwave radiometer for the TOGA Heat Exchange Project

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Mock, Donald R.

    1986-01-01

    The data distributed by the National Space Science Data Center on the Geophysical parameters of precipitable water, sea surface temperature, and surface-level wind speed, measured by the Scanning Multichannel Microwave Radiometer (SMMR) on Nimbus-7, are evaluated with in situ measurements between Jan. 1980 and Oct. 1983 over the tropical oceans. In tracking annual cycles and the 1982-83 E1 Nino/Southern Oscillation episode, the radiometer measurements are coherent with sea surface temperatures and surface-level wind speeds measured at equatorial buoys and with precipitable water derived from radiosonde soundings at tropical island stations. However, there are differences between SMMR and in situ measurements. Corrections based on radiosonde and ship data were derived supplementing correction formulae suggested in the databook. This study is the initial evaluation of the data for quantitative description of the 1982-83 E1 Nino/Southern Oscillation episode. It paves the way for determination of the ocean-atmosphere moisture and latent heat exchanges, a priority of the Tropical Ocean and Global Atmosphere (TOGA) Heat Exchange Program.

  16. Microwave bonding of thin film metal coated substrates

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B. (Inventor); Mai, John D. (Inventor); Jackson, Henry W. (Inventor); Budraa, Nasser K. (Inventor); Pike, William T. (Inventor)

    2004-01-01

    Bonding of materials such as MEMS materials is carried out using microwaves. High microwave absorbing films are placed within a microwave cavity containing other less microwave absorbing materials, and excited to cause selective heating in the skin depth of the films. This causes heating in one place more than another. This thereby minimizes unwanted heating effects during the microwave bonding process.

  17. A Cantor multilayer traveling wave applicator for microwave heating: Numerical analysis and design

    NASA Astrophysics Data System (ADS)

    Chiadini, F.; Diovisalvi, A.; Fiumara, V.; Scaglione, A.

    2014-12-01

    A traveling wave applicator particularly suitable for heating low loss materials is described. The applicator consists of a dielectric Cantor multilayer inserted in a single-mode rectangular metallic waveguide. Field localization phenomenon occurring in the multilayer allows high field amplitude (several times the amplitude of the incident field) to be obtained in a load placed at the center of the applicator. Design examples and numerical characterization of an applicator in WR-284 waveguide operating at 2.45 GHz are presented for cylindrical and planar loads. Results show that the proposed applicator can significantly enhance the effectiveness of the heating process.

  18. Performance of male broiler chicks exposed to heat from infrared or microwave sources

    SciTech Connect

    Morrison, W.D.; Amyot, E.; McMillan, I.; Otten, L.; Pei, D.C.

    1987-11-01

    In eight trials, 240 male broiler birds, initially 7 days old, were randomly allocated to three treatments. Treatments were: continuous infrared (CI), intermittent infrared (II; 4 min on, 2 min off, 10 cycles/h), and intermittent microwaves (IM; 2 min on, 4 min off, 10 cycles/h). At the conclusion of the 14-day experimental period the 21-day-old birds were killed. Although there were significant differences (P less than or equal to .05) in mean gain over the 2-wk treatment period between trials, no differences (P greater than .05) were attributed to treatments. There were, however, significant differences in feed:gain ratios between trials and between treatments. Feed:gain ratios of birds kept under CI and II treatments did not differ significantly (P greater than .05). However, feed:gain ratios, 1.61 +/- .04 and 1.57 +/- .04 for CI and II, respectively, differed significantly (P less than or equal to .05) from that of the IM treatment (1.76 +/- .04). The protein content of chicks under II was significantly (P less than or equal to .05) lower than that of birds under IM. There were no differences (P greater than .05) in fat, ash, calcium, and phosphorus content of chicks among treatments.

  19. Rapid and Sensitive Detection of p53 Based on DNA-Protein Binding Interactions Using Silver Nanoparticle Films and Microwave Heating

    PubMed Central

    Mohammed, Muzaffer; Aslan, Kadir

    2014-01-01

    Tumor detection can be carried out via the detection of proteins, such as p53, which is known to play vital role in more than 50% of all cancers affecting humans. Early diagnosis of tumor detection can be achieved by decreasing the lower detection limit of p53 bioassays. Microwave-accelerated bioassay (MAB) technique, which is based on the use of circular bioassay platforms in combination with microwave heating, is employed for the rapid and sensitive detection of p53 protein. Direct sandwich ELISA was constructed on our circular bioassay platforms based on DNA-protein binding interactions. Colorimetric and fluorescence based detection methods were used for room temperature bioassay (control bioassay; total bioassay time is 27 hours) and bioassay using microwave heating (i.e., the MAB technique; total bioassay time is 10 minutes). In the colorimetric based detection, a very high background signal due to the non-specific binding of proteins for the bioassay carried out at room temperature and a LLOD of 0.01 ng/mL for p53 was observed using the MAB technique. The LLOD for the fluorescence-based detection using the MAB technique was found to be 0.01 ng/mL. The use of circular bioassay platforms in the MAB technique results in microwave-induced temperature gradient, where the specific protein binding interactions are significantly accelerated; thereby reducing the background signal and the lower limit of detection of p53 protein. PMID:25568812

  20. Thermal analysis of an indirectly heat pulsed non-volatile phase change material microwave switch

    SciTech Connect

    Young, Robert M. El-Hinnawy, Nabil; Borodulin, Pavel; Wagner, Brian P.; King, Matthew R.; Jones, Evan B.; Howell, Robert S.; Lee, Michael J.

    2014-08-07

    We show the finite element simulation of the melt/quench process in a phase change material (GeTe, germanium telluride) used for a radio frequency switch. The device is thermally activated by an independent NiCrSi (nickel chrome silicon) thin film heating element beneath a dielectric separating it electrically from the phase change layer. A comparison is made between the predicted and experimental minimum power to amorphize (MPA) for various thermal pulse powers and pulse time lengths. By including both the specific heat and latent heat of fusion for GeTe, we find that the MPA and the minimum power to crystallize follow the form of a hyperbola on the power time effect plot. We also find that the simulated time at which the entire center GeTe layer achieves melting accurately matches the MPA curve for pulse durations ranging from 75–1500 ns and pulse powers from 1.6–4 W.

  1. Microwave sintering of ceramics

    SciTech Connect

    Snyder, W.B.

    1989-01-01

    Successful adaptation of microwave heating to the densification of ceramic materials require a marriage of microwave and materials technologies. Using an interdisciplinary team of microwave and materials engineers, we have successfully demonstrated the ability to density ceramic materials over a wide range of temperatures. Microstructural evolution during microwave sintering has been found to be significantly different from that observed in conventional sintering. Our results and those of others indicate that microwave sintering has the potential to fabricate components to near net shape with mechanical properties equivalent to hot pressed or hot isostatically pressed material. 6 refs., 11 figs.

  2. Uniform batch processing using microwaves

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B. (Inventor); Jackson, Henry W. (Inventor)

    2000-01-01

    A microwave oven and microwave heating method generates microwaves within a cavity in a predetermined mode such that there is a known region of uniform microwave field. Samples placed in the region will then be heated in a relatively identical manner. Where perturbations induced by the samples are significant, samples are arranged in a symmetrical distribution so that the cumulative perturbation at each sample location is the same.

  3. X-ray imaging studies of electron cyclotron microwave-heated plasmas in the Tandem Mirror Experiment-Upgrade

    SciTech Connect

    Failor, B.H.

    1986-02-01

    An x-ray pinhole camera designed to efficiently detect photons with energies between 5 and 250 keV was built to image bremsstrahlung emission from a microwave-heated hot electron plasma. This plasma is formed at one of the thermal barrier locations in the Tandem Experiment-Upgrade at Lawrence Livermore National Laboratory. The instrument consists of a lead aperture, an x-ray converter in the form of a sodium-activated cesium iodide scintillator, light intensifier electronics, and a recording medium that may either be high speed film or a CCD array. The nominal spatial and temporal resolutions are one part in 40 and 17 msec, respectively. The component requirements for optimum performance were determined both analytically and by computer simulation, and were verified experimentally. The details of these results are presented. The instrument has been used to measure x-ray emission from the TMX-U west end cell. Data acquired with the x-ray camera has allowed us to infer the temporal evolution of the mirror-trapped electron radial profile.

  4. Design of the waveguide for microwave heating of solid lithium ceramic blankets

    SciTech Connect

    Kustom, R.L.; Fendley, P.; Tidona, J.

    1985-01-01

    A description is given of the design of a dielectric-loaded waveguide for thermohydraulic testing of solid ceramic tritium breeder material in a non-nuclear environment. The dielectric-loaded waveguide provides uniform heating over module surfaces that would face a fusion reactor plasma and simulates the exponential power decay characteristic of the neutron flux over the high power region of the blankets. A 200-MHz design suitable for modules with cross section of up to 20 x 40 cm is presented.

  5. A microwave antigen retrieval method using two heating steps for enhanced immunostaining on aldehyde-fixed paraffin-embedded tissue sections.

    PubMed

    Gu, Ling; Cong, Jing; Zhang, Jie; Tian, Ying-Ying; Zhai, Xiao-Yue

    2016-06-01

    Antigen retrieval is an immunohistochemical procedure that results in better exposure of target antigens in aldehyde-fixed, paraffin-embedded tissue sections to antibodies. However, the commercially recommended or conventional protocols for antigen retrieval do not always succeed in expressing the target antigen. Here, an improved method was developed for antigen retrieval from aldehyde-fixed, paraffin-embedded histological sections. Proliferating cell nuclear antigen (PCNA), tight junction proteins Claudin-2 and Claudin-7, and water channel aquaporins in kidney tissue were selected as test antigens. Typically, PCNA and Claudin-2 and Claudin-7 show negative, weak, or nonspecific immunoreactions with conventional antigen retrieval methods using microwave heating. In the present study, microwave heating was performed twice with an interval of 30 min between the two steps to allow the buffer solution to cool. Sodium citrate buffer (10 mM sodium citrate, pH 6.0) was used for PCNA, and Tris-EDTA buffer (10 mM Tris, 1 mM EDTA, pH 9.0) was used for the Claudins. Compared with conventionally prepared tissues, the tissues exhibited both enhanced and specific immunostaining, and well-preserved morphology. In conclusion, the conventional protocol could be supplemented with a second microwave heating step to improve the expression of antigens that do not respond well to the conventional method. PMID:27002723

  6. Rapid preparation of α-FeOOH and α-Fe{sub 2}O{sub 3} nanostructures by microwave heating and their application in electrochemical sensors

    SciTech Connect

    Marinho, J.Z.; Montes, R.H.O.; Moura, A.P. de; Longo, E.; Varela, J.A.; Munoz, R.A.A.; Lima, R.C.

    2014-01-01

    Graphical abstract: - Highlights: • Simple microwave method leads to the rapid formation of the goethite and hematite. • Homogenous nucleation and growth of particles are controlled by synthesis time. • Modified electrode with α-FeOOH nanoplates improved the electrochemical response. • The sample is directly heated by microwaves and its crystallization is accelerated. • Fe{sup 3+} nanostructures are promising for development of electrochemical sensors. - Abstract: α-FeOOH (goethite) and α-Fe{sub 2}O{sub 3} (hematite) nanostructures have been successfully synthesized using the microwave-assisted hydrothermal (MAH) method and by the rapid burning in a microwave oven of the as-prepared goethite, respectively. The orthorhombic α-FeOOH to rhombohedralα-Fe{sub 2}O{sub 3} structural transformation was observed by X-ray diffraction (XRD) and Raman spectroscopy results. Plates-like α-FeOOH prepared in 2 min and rounded and quasi-octahedral shaped α-Fe{sub 2}O{sub 3} particles obtained in 10 min were observed using field emission gun scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The use of microwave heating allowed iron oxides to be prepared with shorter reaction times when compared to other synthesis methods. α-FeOOH nanoplates were incorporated into graphite-composite electrodes, which presented electrocatalytic properties towards the electrochemical oxidation of ascorbic acid in comparison with unmodified electrodes. This result demonstrates that such α-FeOOH nanostructures are very promising chemical modifiers for the development of improved electrochemical sensors.

  7. Microwave and Millimeter Wave Testing for the Inspection of the Space Shuttle Spray on Foam Insulations (SOFI) and the Acreage Heat Tiles

    NASA Technical Reports Server (NTRS)

    Zoughi, R.; Kharkovsky, S.; Hepburn, F. L.

    2005-01-01

    The utility of microwave and millimeter wave nondestructive testing and evaluation (NDT&E) methods, for testing the Space Shuttle's external he1 tank spray on foam insulation (SOFI) and the acreage heat tiles has been investigated during the past two years. Millimeter wave NDE techniques are capable of producing internal images of SOFI. This paper presents the results of testing several diverse panels with embedded voids and debonds at millimeter wave frequencies. Additionally, the results of testing a set of heat tiles are also presented. Finally, the attributes of these methods as well as the advantageous features associated with these systems are also provided.

  8. Microwave coupler and method

    DOEpatents

    Holcombe, Cressie E.

    1985-01-01

    The present invention is directed to a microwave coupler for enhancing the heating or metallurgical treatment of materials within a cold-wall, rapidly heated cavity as provided by a microwave furnace. The coupling material of the present invention is an alpha-rhombohedral-boron-derivative-structure material such as boron carbide or boron silicide which can be appropriately positioned as a susceptor within the furnace to heat other material or be in powder particulate form so that composites and structures of boron carbide such as cutting tools, grinding wheels and the like can be rapidly and efficiently formed within microwave furnaces.

  9. Microwave coupler and method

    DOEpatents

    Holcombe, C.E.

    1984-11-29

    The present invention is directed to a microwave coupler for enhancing the heating or metallurgical treatment of materials within a cold-wall, rapidly heated cavity as provided by a microwave furnace. The coupling material of the present invention is an alpha-rhombohedral-boron-derivative-structure material such as boron carbide or boron silicide which can be appropriately positioned as a susceptor within the furnace to heat other material or be in powder particulate form so that composites and structures of boron carbide such as cutting tools, grinding wheels and the like can be rapidly and efficiently formed within microwave furnaces.

  10. Pretreatment of banana agricultural waste for bio-ethanol production: individual and interactive effects of acid and alkali pretreatments with autoclaving, microwave heating and ultrasonication.

    PubMed

    Gabhane, Jagdish; William, S P M Prince; Gadhe, Abhijit; Rath, Ritika; Vaidya, Atul Narayan; Wate, Satish

    2014-02-01

    Banana agricultural waste is one of the potential lignocellulosic substrates which are mostly un-utilized but sufficiently available in many parts of the world. In the present study, suitability of banana waste for biofuel production with respect to pretreatment and reducing sugar yield was assessed. The effectiveness of both acid and alkali pretreatments along with autoclaving, microwave heating and ultrasonication on different morphological parts of banana (BMPs) was studied. The data were statistically analyzed using ANOVA and numerical point prediction tool of MINITAB RELEASE 14. Accordingly, the optimum cumulative conditions for maximum recovery of reducing sugar through acid pretreatment are: leaf (LF) as the substrate with 25 min of reaction time and 180°C of reaction temperature using microwave. Whereas, the optimum conditions for alkaline pretreatments are: pith (PH) as the substrate with 51 min of reaction time and 50°C of reaction temperature using ultrasonication (US). PMID:24268472

  11. Fabrication of tin-filled carbon nanofibres by microwave plasma vapour deposition and their in situ heating observation by environmental transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Tokunaga, Tomoharu; Kanematsu, Takumi; Ito, Takahumi; Ota, Takahisa; Hayashi, Yasuhiko; Sasaki, Katsuhiro; Yamamoto, Takahisa

    2013-06-01

    Sn-filled carbon nanofibres (CNFs) are fabricated by microwave plasma chemical deposition. Scanning electron microscopy observations revealed the existence of a Sn island under the CNFs. The structure of the CNFs is investigated, and the behaviour of Sn in the internal space of CNFs is revealed by performing in situ heating observations by environmental transmission electron microscopy (ETEM). ETEM observations reveal that they have low-crystallized carbon wall and Sn occupies not only the CNF's internal space but also its carbon wall. The Sn inside the CNF is completely covered by the carbon wall. Further, the in situ heating observations reveal that Sn within the internal space and the carbon wall of the CNFs diffused to the outside during heating. Moreover, it is found that higher membered carbon rings and defects in the graphite layer act as diffusion routes between disordered carbon layers.

  12. Microwave Oven Observations.

    ERIC Educational Resources Information Center

    Sumrall, William J.; Richardson, Denise; Yan, Yuan

    1998-01-01

    Explains a series of laboratory activities which employ a microwave oven to help students understand word problems that relate to states of matter, collect data, and calculate and compare electrical costs to heat energy costs. (DDR)

  13. Microwaving of normally opaque and semi-opaque substances

    DOEpatents

    Sheinberg, Haskell; Meek, Thomas T.; Blake, Rodger D.

    1990-01-01

    Method of heating small particles using microwave radiation which are not normally capable of being heated by microwaves. The surfaces of the particles are coated with a material which is transparent to microwave radiation in order to cause microwave coupling to the particles and thus accomplish heating of the particles.

  14. Microwaving of normally opaque and semi-opaque substances

    DOEpatents

    Sheinberg, H.; Meek, T.T.; Blake, R.D.

    1990-07-17

    Disclosed is a method of heating small particles using microwave radiation which are not normally capable of being heated by microwaves. The surfaces of the particles are coated with a material which is transparent to microwave radiation in order to cause microwave coupling to the particles and thus accomplish heating of the particles.

  15. Microwave Ablation of Hepatic Malignancy

    PubMed Central

    Lubner, Meghan G.; Brace, Christopher L.; Ziemlewicz, Tim J.; Hinshaw, J. Louis; Lee, Fred T.

    2013-01-01

    Microwave ablation is an extremely promising heat-based thermal ablation modality that has particular applicability in treating hepatic malignancies. Microwaves can generate very high temperatures in very short time periods, potentially leading to improved treatment efficiency and larger ablation zones. As the available technology continues to improve, microwave ablation is emerging as a valuable alternative to radiofrequency ablation in the treatment of hepatic malignancies. This article reviews the current state of microwave ablation including technical and clinical considerations. PMID:24436518

  16. The mineralogical phase transformation of invisible gold-concentrate by microwave heating, and enhancement of their gold leaching rate

    NASA Astrophysics Data System (ADS)

    Bak, Geonyoung; Kim, Bongju; Choi, Nagchoul; Park*, Cheonyoung

    2015-04-01

    In this study, in order to obtain the maximum Au leaching rate, an invisible gold concentrate sample was microwave-treated and a thiourea leaching experiment was performed. It is found that gold exists as invisible as a result of observation with an optical microscope and an electron microscope. As the invisible gold concentrate sample was exposed to microwave longer, its temperature and weight loss were increased together and its S content was decreased. The conditions for the maximum Au leaching rate and the fast leaching effect were a particle size of -325×400 mesh, exposure to microwave for 70 minutes, 1.0 g of thiourea, 0.0504 g of sodium sulfite and 0.425 g of ferric sulfate. However, the condition under which Au was leached out to the maximum was applied to the control sample, but its Au leaching rate was just in a range of 78% to 88%. Such results suggest that the effect of sodium sulfite and ferric sulfate was more effective in the microwave-treated sample than in the control sample. Therefore, it was confirmed that the complete and very fast Au leaching can be achieved by means of the microwave pretreatment of invisible gold concentrate.

  17. Continuous pig iron making by microwave heating with 12.5 kW at 2.45 GHz.

    PubMed

    Hara, Kyosuke; Hayashi, Miyuki; Sato, Motoyasu; Nagata, Kazuhiro

    2011-01-01

    A continuous process of pig iron making using microwave of 2.45 GHz was constructed in a microwave furnace with maximum power of 12.5 kW. Pig iron was produced from the mixed powder of magnetite ore and carbon such as coal, coke and graphite. Molten pig iron initially poured from reaction chamber after about 40 min when temperature attained over 1200 degrees C. After temperature attained at 1400 degrees C, 50 or 200 g of mixed powder was added several times in regular interval and pig iron continuously dropped out from reaction chamber. When mixed powder was supplied, temperature in reaction chamber decreased by about 200 degrees C and recovered during 5 min. Finally, the recovery time of temperature lengthened. In order to make the scale-up of the microwave furnace for iron making, it has been discussed how to improve energy efficiency and to make a preferable construction. PMID:24427877

  18. Heat Sink Effect on Tumor Ablation Characteristics as Observed in Monopolar Radiofrequency, Bipolar Radiofrequency, and Microwave, Using Ex Vivo Calf Liver Model

    PubMed Central

    Pillai, Krishna; Akhter, Javid; Chua, Terence C.; Shehata, Mena; Alzahrani, Nayef; Al-Alem, Issan; Morris, David L.

    2015-01-01

    Abstract Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices. With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored. With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres. Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected. Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5. MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink. PMID:25738477

  19. Heat sink effect on tumor ablation characteristics as observed in monopolar radiofrequency, bipolar radiofrequency, and microwave, using ex vivo calf liver model.

    PubMed

    Pillai, Krishna; Akhter, Javid; Chua, Terence C; Shehata, Mena; Alzahrani, Nayef; Al-Alem, Issan; Morris, David L

    2015-03-01

    Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices.With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored.With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres.Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected.Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5.MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink. PMID:25738477

  20. Microwave sintering of multiple aritcles

    SciTech Connect

    Blake, R.D.; Katz, J.D.

    1992-12-31

    Disclosed are apparatus and method for producing articles of alumina and of alumina and silicon carbide in which the articles are sintered at high temperatures using microwave radiation. The articles are placed in a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled.

  1. Microwave sintering of multiple articles

    DOEpatents

    Blake, Rodger D.; Katz, Joel D.

    1993-01-01

    Apparatus and method for producing articles of alumina and of alumina and silicon carbide in which the articles are sintered at high temperatures using microwave radiation. The articles are placed in a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled.

  2. RFTF ECH microwave system

    SciTech Connect

    Bigelow, T.S.; White, T.L.; Kimrey, H.D.

    1986-01-01

    A Radio-Frequency Test Facility (RFTF) has recently been constructed at Oak Ridge National Laboratory (ORNL) for development and testing of Ion Cyclotron Heating (ICH) antennas under realistic fusion reactor plasma edge conditions. High-power ICH antennas must be immersed in the plasma for proper coupling of rf power and therefore are subject to particle bombardment and heat flux. In RFTF, plasma is generated and heated by electron cyclotron resonance heating (ECRH) with 28-GHz microwave power from a gyrotron tube. The plasma is confined in a simple magnetic mirror formed by two superconducting coils surrounding a box-shaped vacuum vessel. Using 50 kW of microwave power, a plasma with density of 5 x 10/sup 11/ cm/sup 3/ and temperature of 8 eV is obtained, a fairly good fusion research edge plasma. This presentation covers the microwave generation and transmission system plus some of the electron cyclotron heated (ECH) results on RFTF.

  3. An investigation of the thermal shock resistance of lunar regolith and the recovery of hydrogen from lunar soil heated using microwave radiation

    NASA Technical Reports Server (NTRS)

    Meek, T. T.

    1991-01-01

    The objective is to develop a better understanding of the thermal shock properties of lunar regolith sintered using 2.45 GHz electromagnetic radiation and to do a preliminary study into the recovery of bound hydrogen in lunar soil heated using 2.45 GHz radiation. During the first phase of this work, lunar simulant material was used to test whether or not microhardness data could be used to infer thermal shock resistance and later actual lunar regolith was used. Results are included on the lunar regolith since this is of primary concern and not the simulant results. They were similar, however. The second phase investigated the recovery of hydrogen from lunar regolith and results indicate that microwave heating of lunar regolith may be a good method for recovery of bound gases in the regolith.

  4. 21 CFR 1030.10 - Microwave ovens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Microwave ovens. 1030.10 Section 1030.10 Food and... after October 6, 1971. (b) Definitions. (1) Microwave oven means a device designed to heat, cook, or dry...) Cavity means that portion of the microwave oven in which food may be heated, cooked, or dried. (3)...

  5. 21 CFR 1030.10 - Microwave ovens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Microwave ovens. 1030.10 Section 1030.10 Food and... after October 6, 1971. (b) Definitions. (1) Microwave oven means a device designed to heat, cook, or dry...) Cavity means that portion of the microwave oven in which food may be heated, cooked, or dried. (3)...

  6. A novel method of microwave heating mixed liquid-assisted regeneration of V₂O₅-WO₃/TiO₂ commercial SCR catalysts.

    PubMed

    Qiu, Kunzan; Song, Jin; Song, Hao; Gao, Xiang; Luo, Zhongyang; Cen, Kefa

    2015-10-01

    An experimental study on the regeneration of deactivated SCR catalysts was carried out using a microwave-assisted method containing three steps of washing with mixed liquid of ethanol and water, impregnating, and drying. After the regeneration treatment, NO conversion at 320 °C increased from 39 to 90% and vanadium content increased by 62.2%, which were much higher than those regenerated by the traditional method. The more impregnated vanadium was due to the fact that the rapid evaporation of mixed liquid inside the catalyst channels led to the enlargement of surface areas by creating more pores on the catalysts. Meanwhile, with the increasing concentrations of ethanol, the heating rate of the mixed liquid increased, and the volume after complete evaporation of the mixed liquid was gradually reduced. Since higher heating rate and lager volume after the liquid evaporation could help to create more pores, therefore, when the volume ratio of ethanol/mixed solution was 20%, the catalyst obtained the maximum specific surface area, which significantly increased to ca. 123% compared with the deactivated catalyst. In addition, the catalyst dried by microwave exhibited better catalytic activity than that dried in conventional oven. Therefore, this method showed great potential in industrial applications. PMID:25732905

  7. Experimental study on removal of NO using adsorption of activated carbon/reduction decomposition of microwave heating.

    PubMed

    Shuang-Chen, Ma; Yao, Juan-Juan; Gao, Li

    2012-01-01

    Experimental studies were carried out on flue gas denitrification using activated carbon irradiated by microwave. The effects of microwave irradiation power (reaction temperature), the flow rate of flue gas, the concentration of NO and the flue gas coexisting compositions on the adsorption property of activated carbon and denitrification efficiency were investigated. The results show that: the higher of microwave power, the higher of denitrification efficiency; denitrification efficiency would be greater than 99% and adsorption capacity of NO is relatively stable after seven times regeneration if the microwave power is more than 420 W; adsorption capacity of NO in activated carbon bed is 33.24 mg/g when the space velocity reaches 980 per hour; adsorption capacity declines with increasing of the flow rate of flue gas; the change in denitrification efficiency is not obvious with increasing oxygen content in the flue gas; and the maximum adsorption capacity of NO was observed when moisture in flue gas was about 5.88%. However, the removal efficiency of NO reduces with increasing moisture, and adsorption capacity and removal efficiency of NO reduce with increasing of SO2 concentration in the flue gas. PMID:22988643

  8. Plasma-assisted microwave processing of materials

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin (Inventor); Ylin, Tzu-yuan (Inventor); Jackson, Henry (Inventor)

    1998-01-01

    A microwave plasma assisted method and system for heating and joining materials. The invention uses a microwave induced plasma to controllably preheat workpiece materials that are poorly microwave absorbing. The plasma preheats the workpiece to a temperature that improves the materials' ability to absorb microwave energy. The plasma is extinguished and microwave energy is able to volumetrically heat the workpiece. Localized heating of good microwave absorbing materials is done by shielding certain parts of the workpiece and igniting the plasma in the areas not shielded. Microwave induced plasma is also used to induce self-propagating high temperature synthesis (SHS) process for the joining of materials. Preferably, a microwave induced plasma preheats the material and then microwave energy ignites the center of the material, thereby causing a high temperature spherical wave front from the center outward.

  9. Advanced microwave processing concepts

    SciTech Connect

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.

    1997-04-01

    The purpose of this work is to explore the feasibility of several advanced microwave processing concepts to develop new energy-efficient materials and processes. The project includes two tasks: (1) commercialization of the variable-frequency microwave furnace; and (2) microwave curing of polymeric materials. The variable frequency microwave furnace, whose initial conception and design was funded by the AIM Materials Program, allows the authors, for the first time, to conduct microwave processing studies over a wide frequency range. This novel design uses a high-power traveling wave tube (TWT) originally developed for electronic warfare. By using this microwave source, one can not only select individual microwave frequencies for particular experiments, but also achieve uniform power densities over a large area by the superposition of many different frequencies. Microwave curing of various thermoset resins will be studied because it holds the potential of in-situ curing of continuous-fiber composites for strong, lightweight components or in-situ curing of adhesives, including metal-to-metal. Microwave heating can shorten curing times, provided issues of scaleup, uniformity, and thermal management can be adequately addressed.

  10. Advanced microwave processing concepts

    SciTech Connect

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.

    1995-05-01

    The purpose of this work is to explore the feasibility of several advanced microwave processing concepts to develop new energy-efficient materials and processes. The project includes two tasks: (1) commercialization of the variable-frequency microwave furnace; and (2) microwave curing of polymer composites. The variable frequency microwave furnace, whose initial conception and design was funded by the AIC Materials Program, will allow us, for the first time, to conduct microwave processing studies over a wide frequency range. This novel design uses a high-power traveling wave tube (TWT) originally developed for electronic warfare. By using this microwave source, one can not only select individual microwave frequencies for particular experiments, but also achieve uniform power densities over a large area by the superposition of many different frequencies. Microwave curing of thermoset resins will be studied because it hold the potential of in-situ curing of continuous-fiber composites for strong, lightweight components. Microwave heating can shorten curing times, provided issues of scaleup, uniformity, and thermal management can be adequately addressed.

  11. Monitoring the Exchange of Heat and Moisture Between the Land Surface and the Atmosphere in a Field of Corn with Microwave Radiometry

    NASA Astrophysics Data System (ADS)

    Hornbuckle, B. K.; Hornbuckle, B. K.; England, A. W.; England, A. W.

    2001-05-01

    Soil-vegetation-atmosphere transfer (SVAT) models can be used to produce estimates of plant-available water as well as the fluxes of energy and moisture across the land-atmosphere interface. These estimates could be greatly improved by using independent measurements of key state variables to force the model back to its true state. This process is called data assimilation. Microwave radiometry is sensitive to one of these key state variables, the water content of the top few centimeters of the soil. Although several different SVAT models have been developed in the past, they are not suitable for use with current models of microwave emission. We are integrating high-fidelity biophysically-based SVAT and microwave emission models together into comprehensive point-scale Land Surface Process / Radiobrightness (LSP/R) models. LSP/R models will provide the climate modeling community with the physical insight needed to create accurate yet operational land surface parameterizations which can assimilate radiobrightness observations made by current and future microwave remote sensing satellites. We present an overview of data collected during the Seventh Radiobrightness and Energy Balance EXperiment (REBEX-7) held during the summer of 2000. This data will be used to test the SVAT portion of a LSP/R model for field corn. The experiment site in southeastern Michigan was unusually ideal in terms of crop and soil homogeneity and flat terrain with fetches of more than 400 m in the direction of prevailing winds. Detailed measurements of global short- and long-wave radiation, upwelling short-wave radiation, net radiation, precipitation, wind speed, air temperature, relative humidity, air temperature and water vapor pressure gradients, soil temperature, soil moisture, soil heat flux, vegetation biomass and plant-area index, infrared vegetation and soil temperatures, and soil surface roughness were recorded for mature corn. Estimates of sensible and latent heat flux made using the

  12. Comparative Kinetic Study and Microwaves Non-Thermal Effects on the Formation of Poly(amic acid) 4,4′-(Hexafluoroisopropylidene)diphthalic Anhydride (6FDA) and 4,4′-(Hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (BAPHF). Reaction Activated by Microwave, Ultrasound and Conventional Heating

    PubMed Central

    Tellez, Hugo Mendoza; Alquisira, Joaquín Palacios; Alonso, Carlos Rius; Cortés, José Guadalupe López; Toledano, Cecilio Alvarez

    2011-01-01

    Green chemistry is the design of chemical processes that reduce or eliminate negative environmental impacts. The use and production of chemicals involve the reduction of waste products, non-toxic components, and improved efficiency. Green chemistry applies innovative scientific solutions in the use of new reagents, catalysts and non-classical modes of activation such as ultrasounds or microwaves. Kinetic behavior and non-thermal effect of poly(amic acid) synthesized from (6FDA) dianhydride and (BAPHF) diamine in a low microwave absorbing p-dioxane solvent at low temperature of 30, 50, 70 °C were studied, under conventional heating (CH), microwave (MW) and ultrasound irradiation (US). Results show that the polycondensation rate decreases (MW > US > CH) and that the increased rates observed with US and MW are due to decreased activation energies of the Arrhenius equation. Rate constant for a chemical process activated by conventional heating declines proportionally as the induction time increases, however, this behavior is not observed under microwave and ultrasound activation. We can say that in addition to the thermal microwave effect, a non-thermal microwave effect is present in the system. PMID:22072913

  13. The effect of non-contact heating (microwave irradiation) and contact heating (annealing process) on properties and performance of polyethersulfone nanofiltration membranes

    NASA Astrophysics Data System (ADS)

    Mansourpanah, Y.; Madaeni, S. S.; Rahimpour, A.; Farhadian, A.

    2009-07-01

    In this work the effect of microwave irradiation on morphology and performance of polyethersulfone (PES) membranes was investigated. The membranes were prepared with 20 wt.% of PES by phase inversion method. N, N-dimethylformamide (DMF) and mixture of water and ethyl alcohol (90/10 vol.%) were employed as solvent and coagulant respectively. Polyvinylpirrolidone (PVP) with the concentration of 2 wt.% was selected as pore former. The effects of irradiation time (10, 30, 60, 90, 120 s) and microwave power (180, 360, 720 and 900 W) on structure and performance of membranes were studied. Increasing the irradiation time and power caused variation in permeate flux and ion rejection. Moreover, the effects of annealing processes (60, 70, 80 °C) were studied. Transmembrane pressure was selected around 1.5 MPa for all experiments. Scanning electron microscope (SEM) and atomic force microscope (AFM) were employed to describe the surface morphology of the prepared membranes. The effect of microwave irradiation time in different power revealed alterations in membrane surface morphology and AFM images represented that surface parameters (such as surface roughness) have been changed. The membrane exhibited moderate rejection (47%) and low permeate flux (4.5 kg/m 2 h) at 80 °C for NaCl solution. The SEM images indicate that the dense skin layer is formed at 80 °C annealing.

  14. Microwave ion source

    DOEpatents

    Leung, Ka-Ngo; Reijonen, Jani; Thomae, Rainer W.

    2005-07-26

    A compact microwave ion source has a permanent magnet dipole field, a microwave launcher, and an extractor parallel to the source axis. The dipole field is in the form of a ring. The microwaves are launched from the middle of the dipole ring using a coaxial waveguide. Electrons are heated using ECR in the magnetic field. The ions are extracted from the side of the source from the middle of the dipole perpendicular to the source axis. The plasma density can be increased by boosting the microwave ion source by the addition of an RF antenna. Higher charge states can be achieved by increasing the microwave frequency. A xenon source with a magnetic pinch can be used to produce intense EUV radiation.

  15. Energy filtering transmission electron microscopy immunocytochemistry and antigen retrieval of surface layer proteins from Tannerella forsythensis using microwave or autoclave heating with citraconic anhydride.

    PubMed

    Moriguchi, K; Mitamura, Y; Iwami, J; Hasegawa, Y; Higuchi, N; Murakami, Y; Maeda, H; Yoshimura, F; Nakamura, H; Ohno, N

    2012-11-01

    Tannerella forsythensis (Bacteroides forsythus), an anaerobic Gram-negative species of bacteria that plays a role in the progression of periodontal disease, has a unique bacterial protein profile. It is characterized by two unique protein bands with molecular weights of more than 200 kDa. It also is known to have a typical surface layer (S-layer) consisting of regularly arrayed subunits outside the outer membrane. We examined the relationship between high molecular weight proteins and the S-layer using electron microscopic immunolabeling with chemical fixation and an antigen retrieval procedure consisting of heating in a microwave oven or autoclave with citraconic anhydride. Immunogold particles were localized clearly at the outermost cell surface. We also used energy-filtering transmission electron microscopy (EFTEM) to visualize 3, 3'-diaminobenzidine tetrahydrochloride (DAB) reaction products after microwave antigen retrieval with 1% citraconic anhydride. The three-window method for electron spectroscopic images (ESI) of nitrogen by the EFTEM reflected the presence of moieties demonstrated by the DAB reaction with horseradish peroxidase (HRP)-conjugated secondary antibodies instead of immunogold particles. The mapping patterns of net nitrogen were restricted to the outermost cell surface. PMID:22984898

  16. Conventional and Microwave Joining of Silicon Carbide Using Displacement Reactions

    NASA Technical Reports Server (NTRS)

    Kingsley, J.; Yiin, T.; Barmatz, M.

    1995-01-01

    Microwave heating was used to join Silicon Carbide rods using a thin TiC /Si tape interlayer . Microwaves quickly heated the rods and tape to temperatures where solid-state displacement reactions between TiC and Si occurred.

  17. Microwave sintering process model.

    PubMed

    Peng, Hu; Tinga, W R; Sundararaj, U; Eadie, R L

    2003-01-01

    In order to simulate and optimize the microwave sintering of a silicon nitride and tungsten carbide/cobalt toolbits process, a microwave sintering process model has been built. A cylindrical sintering furnace was used containing a heat insulating layer, a susceptor layer, and an alumina tube containing the green toolbit parts between parallel, electrically conductive, graphite plates. Dielectric and absorption properties of the silicon nitride green parts, the tungsten carbide/cobalt green parts, and an oxidizable susceptor material were measured using perturbation and waveguide transmission methods. Microwave absorption data were measured over a temperature range from 20 degrees C to 800 degrees C. These data were then used in the microwave process model which assumed plane wave propagation along the radial direction and included the microwave reflection at each interface between the materials and the microwave absorption in the bulk materials. Heat transfer between the components inside the cylindrical sintering furnace was also included in the model. The simulated heating process data for both silicon nitride and tungsten carbide/cobalt samples closely follow the experimental data. By varying the physical parameters of the sintering furnace model, such as the thickness of the susceptor layer, the thickness of the allumina tube wall, the sample load volume and the graphite plate mass, the model data predicts their effects which are helpful in optimizing those parameters in the industrial sintering process. PMID:15323110

  18. Behavioral effects of microwaves

    SciTech Connect

    Stern, S.

    1980-01-01

    Microwaves can produce sensations of warmth and sound in humans. In other species, they also can serve as cues, they may be avoided, and they can disrupt ongoing behavior. These actions appear to be due to heat produced by energy absorption. The rate of absorption depends on the microwave parameters and the electrical and geometric properties of the subject. We therefore, cannot predict the human response to microwaves based on data from other animals without appropriate scaling considerations. At low levels of exposure, microwaves can produce changes in behavior without large, or even measureable, changes in body temperature. Thermoregulatory behavior may respond to those low levels of heat, and thereby affect other behavior occurring concurrently. There are no data that demonstrate that behavioral effects of microwaves depend on any mechanism other than reactions to heat. Our interpretation of whether a reported behavioral effect indicates that microwaves may be hazardous depends on our having a complete description of the experiment and on our criteria of behavioral toxicity.

  19. Solution-processed flexible ZnO transparent thin-film transistors with a polymer gate dielectric fabricated by microwave heating

    NASA Astrophysics Data System (ADS)

    Yang, Chanwoo; Hong, Kipyo; Jang, Jaeyoung; Chung, Dae Sung; An, Tae Kyu; Choi, Woon-Seop; Eon Park, Chan

    2009-11-01

    We report the development of solution-processed zinc oxide (ZnO) transparent thin-film transistors (TFTs) with a poly(2-hydroxyethyl methacrylate) (PHEMA) gate dielectric on a plastic substrate. The ZnO nanorod film active layer, prepared by microwave heating, showed a highly uniform and densely packed array of large crystal size (58 nm) in the [002] direction of ZnO nanorods on the plasma-treated PHEMA. The flexible ZnO TFTs with the plasma-treated PHEMA gate dielectric exhibited an electron mobility of 1.1 cm2 V-1 s-1, which was higher by a factor of ~8.5 than that of ZnO TFTs based on the bare PHEMA gate dielectric.

  20. SPINNING DUST EMISSION: EFFECTS OF IRREGULAR GRAIN SHAPE, TRANSIENT HEATING, AND COMPARISON WITH WILKINSON MICROWAVE ANISOTROPY PROBE RESULTS

    SciTech Connect

    Hoang, Thiem; Lazarian, A.; Draine, B. T.

    2011-11-10

    Planck is expected to answer crucial questions on the early universe, but it also provides further understanding on anomalous microwave emission. Electric dipole emission from spinning dust grains continues to be the favored interpretation of anomalous microwave emission. In this paper, we present a method to calculate the rotational emission from small grains of irregular shape with moments of inertia I{sub 1} {>=} I{sub 2} {>=} I{sub 3}. We show that a torque-free rotating irregular grain with a given angular momentum radiates at multiple frequency modes. The resulting spinning dust spectrum has peak frequency and emissivity increasing with the degree of grain shape irregularity, which is defined by I{sub 1}:I{sub 2}:I{sub 3}. We discuss how the orientation of the dipole moment {mu} in body coordinates affects the spinning dust spectrum for different regimes of internal thermal fluctuations. We show that the spinning dust emissivity for the case of strong thermal fluctuations is less sensitive to the orientation of {mu} than in the case of weak thermal fluctuations. We calculate spinning dust spectra for a range of gas density and dipole moment. The effect of compressible turbulence on spinning dust emission is investigated. We show that the emission in a turbulent medium increases by a factor from 1.2 to 1.4 relative to that in a uniform medium, as the sonic Mach number M{sub s} increases from 2 to 7. Finally, spinning dust parameters are constrained by fitting our improved model to five-year Wilkinson Microwave Anisotropy Probe cross-correlation foreground spectra, for both the H{alpha}-correlated and 100-{mu}m-correlated emission spectra.

  1. Image recorder with microwave fixation

    SciTech Connect

    Hosono, N.; Isaka, K.

    1984-11-13

    The present invention is directed to improvement in an image recorder for recording developed images or toner images by microwave fixation. According to the invention there is used a novel thermoplastic developer comprising of two components. The first component contains a dielectric material which is able to absorb microwave and generate heat by dielectric loss. The second component contains magnetic loss exothermic material. The microwave absorbing power of the first component is improved by heating the first component with heat generated from the second component.

  2. Apparatus and method for microwave processing of materials using field-perturbing tool

    DOEpatents

    Tucker, Denise A.; Fathi, Zakaryae; Lauf, Robert J.

    2001-01-01

    A variable frequency microwave heating apparatus designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity for heating or other selected applications. A field-perturbing tool is disposed within the cavity to perturb the microwave power distribution in order to apply a desired level of microwave power to the workpiece.

  3. Microwave Tokamak Experiment: Overview and status

    SciTech Connect

    Not Available

    1990-05-01

    The Microwave Tokamak Experiment, now under construction at the Laboratory, will use microwave heating from a free-electron laser. The intense microwave pulses will be injected into the tokamak to realize several goals, including a demonstration of the effects of localized heat deposition within magnetically confined plasma, a better understanding of energy confinement in tokamaks, and use of the new free-electron laser technology for plasma heating. 3 figs., 3 tabs.

  4. Microwave heating-induced static magnetic flux penetration in YBa2Cu3O7-δ superconducting thin films

    NASA Astrophysics Data System (ADS)

    Kermorvant, Julien; Mage, Jean-Claude; Marcilhac, Bruno; Lemaître, Yves; Bobo, Jean-François; Jacominus van der Beek, Cornelis

    2012-06-01

    The magneto-optical imaging technique is used to visualize the penetration of the magnetic induction in YBa2Cu3O7-δ thin films during surface resistance measurements. The in situ surface resistance measurements were performed at 7 GHz using the dielectric resonator method. When only the microwave magnetic field Hrf is applied to the superconductor, no Hrf-induced vortex penetration is observed, even at high rf power. In contrast, in the presence of a constant magnetic field superimposed on Hrf, we observe a progression of the flux front as Hrf is increased. A local thermometry method based on the measurement of the resonant frequency of the dielectric resonator placed on the YBa2Cu3O7-δ thin film shows that the Hrf-induced flux penetration is due to the increase of the film temperature.

  5. The effects of torrefaction on compositions of bio-oil and syngas from biomass pyrolysis by microwave heating.

    PubMed

    Ren, Shoujie; Lei, Hanwu; Wang, Lu; Bu, Quan; Chen, Shulin; Wu, Joan; Julson, James; Ruan, Roger

    2013-05-01

    Microwave pyrolysis of torrefied Douglas fir sawdust pellet was investigated to determine the effects of torrefaction on the biofuel production. Compared to the pyrolysis of raw biomass, the increased concentrations of phenols and sugars and reduced concentrations of guaiacols and furans were obtained from pyrolysis of torrefied biomass, indicating that torrefaction as a pretreatment favored the phenols and sugars production. Additionally, about 3.21-7.50 area% hydrocarbons and the reduced concentration of organic acids were obtained from pyrolysis of torrefied biomass. Torrefaction also altered the compositions of syngas by reducing CO2 and increasing H2 and CH4. The syngas was rich in H2, CH4, and CO implying that the syngas quality was significantly improved by torrefaction process. PMID:22840200

  6. More Experiments with Microwave Ovens

    ERIC Educational Resources Information Center

    Vollmer, Michael; Mollmann, Klaus-Peter; Karstadt, Detlef

    2004-01-01

    Microwave ovens can be used to perform exciting demonstrations that illustrate a variety of physics topics. Experiments discussed here show superheating, visualize the inhomogeneous heating that takes place in a microwave and also show how to use a mobile phone to detect radiation leaking from the oven. Finally eggs can give some spectacular…

  7. Numerical 3D modeling of heat transfer in human tissues for microwave radiometry monitoring of brown fat metabolism

    PubMed Central

    Rodrigues, Dario B.; Maccarini, Paolo F.; Salahi, Sara; Colebeck, Erin; Topsakal, Erdem; Pereira, Pedro J. S.; Limão-Vieira, Paulo; Stauffer, Paul R.

    2013-01-01

    Background Brown adipose tissue (BAT) plays an important role in whole body metabolism and could potentially mediate weight gain and insulin sensitivity. Although some imaging techniques allow BAT detection, there are currently no viable methods for continuous acquisition of BAT energy expenditure. We present a non-invasive technique for long term monitoring of BAT metabolism using microwave radiometry. Methods A multilayer 3D computational model was created in HFSS™ with 1.5 mm skin, 3–10 mm subcutaneous fat, 200 mm muscle and a BAT region (2–6 cm3) located between fat and muscle. Based on this model, a log-spiral antenna was designed and optimized to maximize reception of thermal emissions from the target (BAT). The power absorption patterns calculated in HFSS™ were combined with simulated thermal distributions computed in COMSOL® to predict radiometric signal measured from an ultra-low-noise microwave radiometer. The power received by the antenna was characterized as a function of different levels of BAT metabolism under cold and noradrenergic stimulation. Results The optimized frequency band was 1.5–2.2 GHz, with averaged antenna efficiency of 19%. The simulated power received by the radiometric antenna increased 2–9 mdBm (noradrenergic stimulus) and 4–15 mdBm (cold stimulus) corresponding to increased 15-fold BAT metabolism. Conclusions Results demonstrated the ability to detect thermal radiation from small volumes (2–6 cm3) of BAT located up to 12 mm deep and to monitor small changes (0.5 °C) in BAT metabolism. As such, the developed miniature radiometric antenna sensor appears suitable for non-invasive long term monitoring of BAT metabolism. PMID:24244831

  8. Numerical 3D modeling of heat transfer in human tissues for microwave radiometry monitoring of brown fat metabolism

    NASA Astrophysics Data System (ADS)

    Rodrigues, Dario B.; Maccarini, Paolo F.; Salahi, Sara; Colebeck, Erin; Topsakal, Erdem; Pereira, Pedro J. S.; Limão-Vieira, Paulo; Stauffer, Paul R.

    2013-02-01

    Background: Brown adipose tissue (BAT) plays an important role in whole body metabolism and could potentially mediate weight gain and insulin sensitivity. Although some imaging techniques allow BAT detection, there are currently no viable methods for continuous acquisition of BAT energy expenditure. We present a non-invasive technique for long term monitoring of BAT metabolism using microwave radiometry. Methods: A multilayer 3D computational model was created in HFSSTM with 1.5 mm skin, 3-10 mm subcutaneous fat, 200 mm muscle and a BAT region (2-6 cm3) located between fat and muscle. Based on this model, a log-spiral antenna was designed and optimized to maximize reception of thermal emissions from the target (BAT). The power absorption patterns calculated in HFSSTM were combined with simulated thermal distributions computed in COMSOL® to predict radiometric signal measured from an ultra-low-noise microwave radiometer. The power received by the antenna was characterized as a function of different levels of BAT metabolism under cold and noradrenergic stimulation. Results: The optimized frequency band was 1.5-2.2 GHz, with averaged antenna efficiency of 19%. The simulated power received by the radiometric antenna increased 2-9 mdBm (noradrenergic stimulus) and 4-15 mdBm (cold stimulus) corresponding to increased 15-fold BAT metabolism. Conclusions: Results demonstrated the ability to detect thermal radiation from small volumes (2-6 cm3) of BAT located up to 12 mm deep and to monitor small changes (0.5 °C) in BAT metabolism. As such, the developed miniature radiometric antenna sensor appears suitable for non-invasive long term monitoring of BAT metabolism.

  9. Microwave assisted centrifuge and related methods

    DOEpatents

    Meikrantz, David H [Idaho Falls, ID

    2010-08-17

    Centrifuge samples may be exposed to microwave energy to heat the samples during centrifugation and to promote separation of the different components or constituents of the samples using a centrifuge device configured for generating microwave energy and directing the microwave energy at a sample located in the centrifuge.

  10. Atmospheric pressure microwave assisted heterogeneous catalytic reactions.

    PubMed

    Chemat-Djenni, Zoubida; Hamada, Boudjema; Chemat, Farid

    2007-01-01

    The purpose of the study was to investigate microwave selective heating phenomena and their impact on heterogeneous chemical reactions. We also present a tool which will help microwave chemists to answer to such questions as "My reaction yields 90% after 7 days at reflux; is it possible to obtain the same yield after a few minutes under microwaves?" and to have an approximation of their reactions when conducted under microwaves with different heterogeneous procedures. This model predicting reaction kinetics and yields under microwave heating is based on the Arrhenius equation, in agreement with experimental data and procedures. PMID:17909495

  11. Adhesive bonding using variable frequency microwave energy

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

    1998-09-08

    Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

  12. Adhesive bonding using variable frequency microwave energy

    DOEpatents

    Lauf, Robert J.; McMillan, April D.; Paulauskas, Felix L.; Fathi, Zakaryae; Wei, Jianghua

    1998-01-01

    Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy.

  13. Adhesive bonding using variable frequency microwave energy

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

    1998-08-25

    Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

  14. Microwave Ovens

    MedlinePlus

    ... Required Reports for the Microwave Oven Manufacturers or Industry Exemption from Certain Reporting and Recordkeeping Requirements for ... Microwave Ovens (PDF) (PDF - 2.5MB) FDA eSubmitter Industry Guidance - Documents of Interest Notifications to Industry (PDF ...

  15. Effect of microwave reflection from the region of electron cyclotron resonance heating in the L-2M stellarator

    SciTech Connect

    Batanov, G. M.; Borzosekov, V. D.; Kolik, L. V.; Konchekov, E. M.; Malakhov, D. V.; Petrov, A. E.; Sarksyan, K. A.; Sakharov, A. S. Skvortsova, N. N.; Stepakhin, V. D.; Kharchev, N. K.

    2013-11-15

    In experiments on electron cyclotron resonance (ECR) heating of plasma at the second harmonic of the electron gyrofrequency in the L-2M stellarator, the effect of partial reflection of high-power gyrotron radiation from the ECR heating region located in the center of the plasma column was revealed. The reflection coefficient is found to be on the order of 10{sup −3}. The coefficient of reflection of an extraordinary wave from the second-harmonic ECR region is calculated in the one-dimensional full-wave model. The calculated and measured values of the reflection coefficient are found to coincide in order of magnitude.

  16. Epoxy composite processing in a microwave part-shaped cavity

    SciTech Connect

    Shidaker, T.A.; Hawley, M.C.

    1997-12-31

    A microwave part-shaped applicator was designed to be competitive with conventional liquid composite molding processes. Three glass-reinforced diglycidyl ether of bisphenol A epoxy composites with a diaminodiphenyl sulfone curative are processed in the part-shaped cavity by microwave heating, conventional heating, and hybrid heating where both microwave and conduction heating are employed. Hybrid heating provided superior heating uniformity due to complementary heat transfer mechanisms: an outward flux of thermal energy from microwave heating combined with an inward flux of energy associated with conventional heating. Because of the penetrating nature of microwave energy, the time required to attain the cure temperature in the composite center was reduced by more than 85% using microwave and hybrid heating methods.

  17. Microwave sintering and in-situ transmission electron microscopy heating study of Li1·2(Mn0·53Co0.27)O2 with improved electrochemical performance

    NASA Astrophysics Data System (ADS)

    Wu, Jingjing; Liu, Xialin; Bi, Han; Song, Yuanzhe; Wang, Chao; Cao, Qi; Liu, Zhengwang; Wang, Min; Che, Renchao

    2016-09-01

    Li1·2(Mn0·53Co0.27)O2 cathode material was successfully synthesized using a microwave sintering method. The as-prepared material remained in an octahedral shape after sintering at 800 °C with a rapid heating rate of 35 °C min-1. The as-prepared sample was demonstrated to have better electrochemical performance than that synthesized using a conventional method. The enhanced electrochemical performance can be ascribed to the minor change in material morphology and less particle agglomeration in the macroscopic scale, which depends on the rapid-sintering mechanism provided by microwave sintering. The rapid-sintering mechanism was studied in an in-situ transmission electron microscopy (TEM) heating experiment, which directly presented the crystal growth process and the evidence for the morphological damage of Li1·2(Mn0·53Co0.27)O2 materials at approximately 830 °C.

  18. Stability of encapsulated beef-like flavourings prepared from enzymatically hydrolysed mushroom proteins with other precursors under conventional and microwave heating.

    PubMed

    Lotfy, Shereen N; Fadel, Hoda H M; El-Ghorab, Ahmed H; Shaheen, Mohamed S

    2015-11-15

    A comparative study was carried out between two beef-like flavourings prepared by conventional and microwave heating (CBF and MBF) of enzymatic hydrolysate of mushroom protein with other flavour precursors. GC-MS analysis of the isolated volatiles revealed that the thiol containing compounds were the predominate in both samples. However, MBF comprised higher concentration of these compounds (13.84 ± 0.06%) than CBF (10.74 ± 0.06%). The effect of microencapsulation with gum Arabic by using spray drying on the odour profile and volatile compounds of the two encapsulated samples (E-CBF and E-MBF) was investigated. The results revealed significant qualitative and quantitative variations in the volatiles of both samples. The highly volatile compounds decreased remarkably in concentration with encapsulation, while the pyrazines, thiazoles and disulphides showed opposite trend. The significant decrease in the thiol containing compounds in E-CBF and E-MBF were attributed to their oxidation to other compounds such as disulphide compounds which showed significant increase in the encapsulated samples. PMID:25976991

  19. Preparation of AgInS2 nanoparticles by a facile microwave heating technique; study of effective parameters, optical and photovoltaic characteristics

    NASA Astrophysics Data System (ADS)

    Tadjarodi, Azadeh; Cheshmekhavar, Amir Hossein; Imani, Mina

    2012-12-01

    In this work, AgInS2 (AIS) semiconductor nanoparticles were synthesized by an efficient and facile microwave heating technique using several sulfur sources and solvents in the different reaction times. The SEM images presented the particle morphology for all of the obtained products in the arranged reaction conditions. The particle size of 70 nm was obtained using thioacetamide (TAA), ethylene glycol (EG) as the sulfur source and solvent, respectively at the reaction time of 5 min. It was found that the change of the mentioned parameters lead to alter on the particle size of the resulting products. The average particle size was estimated using a microstructure measurement program and Minitab statistical software. The optical band gap energy of 1.96 eV for the synthesized AIS nanoparticles was determined by the diffuse reflectance spectroscopy (DRS). AgInS2/CdS/CuInSe2 heterojunction solar cell was constructed and photovoltaic parameters, i.e., open-circuit voltage (Voc), short-circuit current (Jsc) and fill factor (FF) were estimated by photocurrent-voltage (I-V) curve. The calculated fill factor of 30% and energy conversion efficiency of 1.58% revealed the capability of AIS nanoparticles to use in the solar cell devices.

  20. Preparation of gold nanoparticles by microwave heating and application of spectroscopy to study conjugate of gold nanoparticles with antibody E. coli O157:H7

    NASA Astrophysics Data System (ADS)

    Thanh Ngo, Vo Ke; Phuong Uyen Nguyen, Hoang; Phat Huynh, Trong; Nguyen Pham Tran, Nguyen; Lam, Quang Vinh; Dat Huynh, Thanh

    2015-09-01

    Gold nanoparticles (AuNPs) of 15-20 nm size range have attracted attention for producing smart sensing devices as diagnostic tools in biomedical sciences. Citrate capped AuNPs are negatively charged, which can be exploited for electrostatic interactions with some positively charged biomolecules like antibodies. In this paper we describe a method for the low cost synthesis of gold nanoparticles using sodium citrate (Na3Ct) reduction in chloroauric acid (HAuCl4.3H2O) by microwave heating (diameter about 13-15 nm). Gold nanoparticles were functionalized with surface activation by 3-mercaptopropionic acid for attaching antibody. These nanoparticles were then reacted with anti-E. coli O157:H7, using N-hydroxy succinimide (NHS) and carbondimide hydrochloride (EDC) coupling chemistry. The product was characterized with UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy and zeta potential. In addition, the binding of antibody-gold nanoparticles conjugates to E. coli O157:H7 was demonstrated using transmission electron microscopy (TEM).

  1. Comment on ``Dynamics of glass-forming liquids. XIII. Microwave heating in slow motion'' [J. Chem. Phys. 130, 194509 (2009)

    NASA Astrophysics Data System (ADS)

    Johari, G. P.

    2012-07-01

    Critical reading of the dielectric method and data in the paper [W. Huang and R. Richert, J. Chem. Phys. 130, 194509 (2009)], 10.1063/1.3139519 showed that (i) the large inter-electrode area of the Teflon spacer used in the dielectric cell affected the spectral data and (ii) the measured Δɛ of propylene carbonate after making the spacer area correction is 1.8-times the known value, indicating errors from unknown sources. This puts into question their support for the dynamic heterogeneity view, and their inference on the magnitude of configurational heat capacity.

  2. Microwave enhanced sintering of ceramics

    SciTech Connect

    Wroe, F.C.R.; Rowley, A.T.

    1995-12-31

    It is now well known that microwave dielectric heating can be used to increase the Wintering rates and to reduce the sintering times of ceramic materials. However, the nature of the mechanism causing this enhanced sintering is still far from understood, with many workers attributing the effect to a reduction in the activation energy even though there is no real physical basis for this assumption. Although the mechanism is not understood, many results have indicated that the effect is non thermal in nature, i.e. the enhancement would not be reproduced if conventional heat could be applied in exactly the same way (volumetrically) as microwave heat. By careful control of the relative proportions of microwave and conventional heating, it has been possible to separate the thermal (heating) effects from the non-thermal effects. This paper discusses the results obtained, and show that they are consistent with recent theories of enhanced diffusion.

  3. Heat distribution ceramic processing method

    DOEpatents

    Tiegs, Terry N.; Kiggans, Jr., James O.

    2001-01-01

    A multi-layered heat distributor system is provided for use in a microwave process. The multi-layered heat distributors includes a first inner layer of a high thermal conductivity heat distributor material, a middle insulating layer and an optional third insulating outer layer. The multi-layered heat distributor system is placed around the ceramic composition or article to be processed and located in a microwave heating system. Sufficient microwave energy is applied to provide a high density, unflawed ceramic product.

  4. Observation of Diffusive Flows during Liquid Phase Microwave Sintering

    NASA Astrophysics Data System (ADS)

    Watanabe, Takashi; Sato, Motoyasu; Takayama, Sadatsugu; Matsubara, Akihiro

    Experiments at the microscopic scale show the shrinking and melting processes of porcelain by microwave and infrared heating. Microscopic in-situ observations reveal that the porcelain is sintered rapidly and volumetrically by microwaves. This experiment clarifies the differences between microwave and conventional heating.

  5. Microwave detector

    DOEpatents

    Meldner, Heiner W.; Cusson, Ronald Y.; Johnson, Ray M.

    1986-01-01

    A microwave detector (10) is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite (26, 28) produces a magnetization field flux that links a B-dot loop (16, 20). The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means (18, 22) are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

  6. Microwave detector

    DOEpatents

    Meldner, H.W.; Cusson, R.Y.; Johnson, R.M.

    1985-02-08

    A microwave detector is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite produces a magnetization field flux that links a B-dot loop. The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

  7. Airborne Passive Microwave Measurements from the AMISA 2008 Science Campaign for Modeling of Arctic Sea Ice Heating

    NASA Astrophysics Data System (ADS)

    Zucker, M. L.; Gasiewski, A. J.; CenterEnvironmental Technology

    2011-12-01

    While climate changes in the Arctic are occurring more rapidly than anywhere else on Earth model-based predictions of sea ice extent are at once both more optimistic than the data suggest and exhibit a high degree of variability. It is believed that this high level of uncertainty is the result of an inadequate quantitative understanding of surface heating mechanisms, which in large part is due to a lack of high spatial resolution data on boundary layer and surface energy processes during melt and freezeup. In August 2008 the NASA Arctic Mechanisms of Interactions between the Surface and Atmosphere (AMISA) campaign, in conjunction with the Swedish-led Arctic Summer Cloud-Ocean Study (ASCOS) conducted coordinated high spatial resolution measurements of geophysical parameters in the Arctic relevant to atmospheric-sea ice interaction. The IPY-approved AMISA campaign used airborne radiometers, including the Polarimetric Scanning Radiometer (PSR) system, a suite of L-band to V-band fixed-beam radiometers for cloud liquid and water vapor measurement, short and longwave radiation sensors, meteorological parameters from cloud size distribution probes, GPS dropsondes, and aerosol sensors. Calibration of the PSR is achieved through periodic observations of stable references such as thermal blackbody targets and noise diodes. A combination of methods using both infrequent external thermal blackbody views and brief frequent internal noise sources has proven practical for airborne systems such as the PSR and is proposed for spaceborne systems such as GeoMAS. Once radiometric data is calibrated it is then rasterized into brightness temperature images which are then geo-located and imported into Google EarthTM. An example brightness temperature map from the AMISA 2008 campaign is included in this abstract. The analysis of this data provides a basis for the development of a heat flux model needed to decrease the uncertainly in weather and climate predictions within the Arctic. In

  8. Heat treating of manufactured components

    DOEpatents

    Ripley, Edward B.

    2012-05-22

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material is disclosed. The system typically includes an insulating vessel placed within a microwave applicator chamber. A moderating material is positioned inside the insulating vessel so that a substantial portion of the exterior surface of each component for heat treating is in contact with the moderating material.

  9. Microwave processing of radioactive materials-I

    SciTech Connect

    White, T.L.; Berry, J.B.

    1989-01-01

    This paper is the first of two papers that reviews the major past and present applications of microwave energy for processing radioactive materials, with particular emphasis on processing radioactive wastes. Microwave heating occurs through the internal friction produced inside a dielectric material when its molecules vibrate in response to an oscillating microwave field. For this presentation, we shall focus on the two FCC-approved microwave frequencies for industrial, scientific, and medical use, 915 and 2450 MHz. Also, because of space limitations, we shall postpone addressing plasma processing of hazardous wastes using microwave energy until a later date. 13 refs., 4 figs.

  10. An airborne study of microwave surface sensing and boundary layer heat and moisture fluxes for Project FIFE

    NASA Technical Reports Server (NTRS)

    Kelly, Robert D.

    1989-01-01

    This is the third semiannual status report describing the University of Wyoming participation in project FIFE, under NASA Grant NAG 5-913. The reader is referred to the first and second semiannual status reports for this grant for descriptions of University of Wyoming participation in the field operations of 1987. This report is concerned with continuing analysis of field data. Most of the instrument calibration effort has concentrated on interpretation and use of the high-rate water vapor measurements with the University of Wyoming Lyman-alpha device. In addition, fluxes of water vapor have been corrected for sensible heat flux, and all the high-rate (10 Hz for the Wyoming King Air) data have been filtered before the flux calculations. For each flight the Lyman-alpha data (10 Hz) are calibrated against the Cambridge dew-point hygrometer (1 Hz), by using data from the take-off sounding. The reasoning here is that the takeoff sounding (held to 500 fpm rate-of-climb specifically for the calibration) covers the widest range of humidity conditions of any sequence of the flight. For each takeoff sounding, then, the Lyman-alpha data, averaged to 1 Hz, are matched to the dewpoint data with a second-order least-squares fit. The resulting quadratic equation is then used in all subsequent analyses to convert the Lyman-alpha voltages to vapor desities for that specific flight. An alternative method is to use the range of fluctuation for the same two devices from horizontal passes to establish the calibration function. However, since the Lyman-alpha data are used only in the flux calculations, i.e., only the fluctuation and not the absolute values are used, this method is thought unnecessary.

  11. Interaction of microwaves and germinating seeds

    SciTech Connect

    Shafer, F.L.

    1987-01-01

    The preliminary investigation measured the internal metabolic process by ATP production. Leakage of ions and organic material from germinating seeds indicated that membranes are a target of microwaves and heat. Electron photo-micrographs showed an increase in damage to membranes as heat and microwave treatments were increased. The second phase of this investigation was concerned with determining some of the biological activity at the initiation of germination of wheat seed, Triticum aestivum L., using a resonating microwave cavity oscillating at 9.3 GHz as a probe. Direct current conductivity measurements were also made on the seeds as a means of confirming the observations made with the microwave cavity.

  12. Process for microwave sintering boron carbide

    DOEpatents

    Holcombe, Cressie E.; Morrow, Marvin S.

    1993-01-01

    A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

  13. Process for microwave sintering boron carbide

    DOEpatents

    Holcombe, C.E.; Morrow, M.S.

    1993-10-12

    A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

  14. Microwave induced pyrolysis of oil palm biomass.

    PubMed

    Salema, Arshad Adam; Ani, Farid Nasir

    2011-02-01

    The purpose of this paper was to carry out microwave induced pyrolysis of oil palm biomass (shell and fibers) with the help of char as microwave absorber (MA). Rapid heating and yield of microwave pyrolysis products such as bio-oil, char, and gas was found to depend on the ratio of biomass to microwave absorber. Temperature profiles revealed the heating characteristics of the biomass materials which can rapidly heat-up to high temperature within seconds in presence of MA. Some characterization of pyrolysis products was also presented. The advantage of this technique includes substantial reduction in consumption of energy, time and cost in order to produce bio-oil from biomass materials. Large biomass particle size can be used directly in microwave heating, thus saving grinding as well as moisture removal cost. A synergistic effect was found in using MA with oil palm biomass. PMID:20970995

  15. The Liverpool Microwave Palaeointensity System

    NASA Astrophysics Data System (ADS)

    Hill, Mimi; Biggin, Andrew; Hawkins, Louise; Hodgson, Emma; Hurst, Elliot

    2016-04-01

    The motivation for the group at Liverpool in the 1990s (led by John Shaw and Derek Walton) to start experimenting with using microwaves to demagnetise and remagnetise palaeomagnetic samples, rather than heating using conventional ovens, was to reduce laboratory induced alteration in absolute palaeointensity experiments. As with other methods, the non-ideal effects of grain size and naturally altered remanence must still be addressed. From humble beginnings using a domestic microwave oven the current 4th generation microwave system (MWS) has developed in to an integrated combined 14 GHz microwave resonant cavity and SQUID magnetometer system. The MWS is designed to investigate one 5 mm diameter sample at a time with microwave exposure (the equivalent of a heating step in conventional experiments) ranging from a few seconds up to around a minute. Each experiment (protocol, checks, direction and strength of applied field, number of steps etc) can be tailored to the behaviour of each individual sample. There have been many published studies demonstrating the equivalence of conventional thermal (Thellier) and microwave techniques using both artificial and natural remanence and also that the microwave method can indeed reduce laboratory induced alteration. Here an overview of the present MWS including a discussion of the physical processes occurring will be given. Examples of current projects (both archaeological and geological) utilising the method will also be described. Finally, future developments and applications of the method will be discussed.

  16. The Microwave Tokamak Experiment (MTX)

    SciTech Connect

    Thomassen, K.I.; Cohen, B.I.; Hooper, E.B.; Lang, D.D.; Nevins, W.M.

    1987-10-02

    A new experimental facility is being assembled at the Lawrence Livermore National Laboratory (LLNL) for studying microwave propagation and absorption in high density plasmas. A unique feature of the facility is the free electron laser (FEL) used to generate high peak power microwaves at 250 GHz, at a repetition rate so as to produce up to 2 MW of average power for up to 30 s. Called the Microwave Tokamak Experiment (MTX), the facility will be used for studies of plasma heating, current drive, and confinement.

  17. CONTINUOUS MICROWAVE REACTORS FOR ORGANIC SYNTHESIS: HYDRODECHLORINATION AND HYDROLYSIS

    EPA Science Inventory

    Microwave heating has been sought as a convenient way of enhancing chemical processes. The advantages of microwave heating, such as selective direct heating of materials of a catalytic site, minimized fouling on hot surfaces, process simplicity, rapid startup, as well as the poss...

  18. CONTINUOUS FLOW MICROWAVE REACTORS FOR ORGANIC SYNTHESIS: HYDRODECHLORINATION, HETROCYCLIZATION, ISOMERIZATION

    EPA Science Inventory

    Microwave heating has been sought as a convenient way of enhancing chemical processes. The advantages of microwave heating, such as selective direct heating of materials of a catalytic site, minimized fouling on hot surfaces, process simplicity, rapid startup, as well as the pos...

  19. Microwave generator

    SciTech Connect

    Kwan, T.J.T.; Snell, C.M.

    1987-03-31

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit there through effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators. 6 figs.

  20. Microwave torrefaction of rice straw and Pennisetum.

    PubMed

    Huang, Y F; Chen, W R; Chiueh, P T; Kuan, W H; Lo, S L

    2012-11-01

    Microwave torrefaction of rice straw and pennisetum was researched in this article. Higher microwave power levels contributed to higher heating rate and reaction temperature, and thus produced the torrefied biomass with higher heating value and lower H/C and O/C ratios. Kinetic parameters were determined with good coefficients of determination, so the microwave torrefaction of biomass might be very close to first-order reaction. Only 150W microwave power levels and 10min processing time were needed to meet about 70% mass yield and 80% energy yield for torrefied biomass. The energy density of torrefied biomass was about 14% higher than that of raw biomass. The byproducts (liquid and gas) possessed about 30% mass and 20% energy of raw biomass, and they can be seen as energy sources for heat or electricity. Microwave torrefaction of biomass could be a competitive technology to employ the least energy and to retain the most bioenergy. PMID:22929739

  1. Micro/milliflow processing with selective catalyst microwave heating in the Cu-catalyzed Ullmann etherification reaction: a μ(2)-process.

    PubMed

    Benaskar, Faysal; Patil, Narendra G; Rebrov, Evgeny V; Ben-Abdelmoumen, Alladin; Meuldijk, Jan; Hulshof, Lumbertus A; Hessel, Volker; Schouten, Jaap C

    2013-02-01

    A μ(2)-process in the Ullmann-type C-O coupling of potassium phenolate and 4-chloropyridine was successfully performed in a combined microwave (MW) and microflow process. Selective MW absorption in a micro-fixed-bed reactor (μ-FBR) by using a supported Cu nanocatalyst resulted in an increased activity compared to an oil-bath heated process. Yields of up to 80 % were attained by using a multisegmented μ-FBR without significant catalyst deactivation. The μ-FBR was packed with beads coated with Cu/TiO(2) and CuZn/TiO(2) catalysts. Temperature measurements along axial positions of the reactor were performed by using a fiber-optic probe in the catalyst bed. The simultaneous application of MW power and temperature sensors resulted in an isothermal reactor at 20 W. Initially, only solvent was used to adjust the MW field density in the cavity and optimize the power utility. Subsequently, the reaction mixture was added to ensure the maximum MW power transfer by adjusting the waveguide stub tuners to steady-state operations as a result of the changed reaction mixture composition and, therefore, the dielectric properties. Finally, the beneficial influence of the Cu/TiO(2)- and CuZn/TiO(2)-coated glass beads (200 μm) on the MW absorption as a result of the additional absorbing effect of the metallic Cu nanoparticles was optimized in a fine-tuning step. For the catalyst synthesis, various sol-gel, deposition, and impregnation methods provided Cu catalyst loadings of around 1 wt %. The addition of Zn to the Cu nanocatalyst revealed an increased catalyst activity owing to the presence of stable Cu(0). Multilaminar mixing was necessary because of the large difference in fluid viscosities. To the best of our knowledge, this work is the first extended experimental survey of the decisive parameters to combine microprocess and single-mode MW technology following the concepts of "novel process windows" for organic syntheses. PMID:23193030

  2. Microwave-assisted cobinamide synthesis.

    PubMed

    O Proinsias, Keith; Karczewski, Maksymilian; Zieleniewska, Anna; Gryko, Dorota

    2014-08-15

    We present a new method for the preparation of cobinamide (CN)2Cbi, a vitamin B12 precursor, that should allow its broader utility. Treatment of vitamin B12 with only NaCN and heating in a microwave reactor affords (CN)2Cbi as the sole product. The purification procedure was greatly simplified, allowing for easy isolation of the product in 94% yield. The use of microwave heating proved beneficial also for (CN)2Cbi(c-lactone) synthesis. Treatment of (CN)2Cbi with triethanolamine led to (CN)2Cbi(c-lactam). PMID:25058239

  3. Organic Synthesis Using Microwaves and Supported Reagents

    EPA Science Inventory

    In the electromagnetic radiation region, microwaves (0.3GHz-300GHz) lie between radiowave (Rf) and infrared (IR) frequencies with relatively large wavelengths (1 mm-1 m). Microwaves, non-ionizing radiation incapable of breaking bonds, are a form of energy that manifest as heat t...

  4. Endothelium Preserving Microwave Treatment for Atherosclerosis

    NASA Technical Reports Server (NTRS)

    Fink, Patrick; Arndt, G. D.; Ngo, Phong

    2003-01-01

    This slide presentation reviews the use of microwave technology for treating Atherosclerosis while preserving the endothelium. The system uses catheter antennas as part of the system that is intended to treat atherosclerosis. The concept is to use a microwave catheter for heating the atherosclerotic lesions, and reduce constriction in the artery.

  5. Method of sintering materials with microwave radiation

    DOEpatents

    Kimrey, Jr., Harold D.; Holcombe, Jr., Cressie E.; Dykes, Norman L.

    1994-01-01

    A method of sintering ceramic materials following: A compacted article comprising inorganic particles coated with carbon is provided, the carbon providing improved microwave coupling. The compacted article is then heated by microwave radiation to a temperature and for a period of time sufficient to sinter the compacted article.

  6. Thermal imaging of subsurface microwave absorbers in dielectric materials

    NASA Astrophysics Data System (ADS)

    Osiander, Robert; Maclachlan Spicer, Jane W.; Murphy, John C.

    1994-03-01

    The use of microwaves as a heating source in time-resolved IR radiometry provides the ability to heat surface and subsurface microwave-absorbing regions of a specimen directly. This can improve the contrast and spatial resolution of such regions and enhance their detectibility when compared with conventional laser or flashlamp sources. The experiments reported here use microwave heating with IR detection. Results on plexiglass-water-Teflon test specimens with absorbers at different depths in the sample are described by a 1D analytical model. Measurements using microwave and optical heating on epoxy-coated steel pipes are compared and demonstrate the ability of microwave heating to detect subsurface water voids very efficiently. Other applications of the method to microwave imaging, field mapping and imaging of defects in composite materials are discussed.

  7. MICROWAVE POPCORN EMISSIONS RELEASED DURING COOKING AND BAG OPENING

    EPA Science Inventory

    Data are not currently available on the contaminants released when microwave popcorn, flavorings and bags are heated to microwave temperatures. Thus, the primary goal of this work is to identify and quantify contaminants emitted while popping and opening a bag of microwave popcor...

  8. Microwave Sterilization and Depyrogenation System

    NASA Technical Reports Server (NTRS)

    Akse, James R.; Dahl, Roger W.; Wheeler, Richard R., Jr.

    2009-01-01

    A fully functional, microgravity-compatible microwave sterilization and depyrogenation system (MSDS) prototype was developed that is capable of producing medical-grade water (MGW) without expendable supplies, using NASA potable water that currently is available aboard the International Space Station (ISS) and will be available for Lunar and planetary missions in the future. The microwave- based, continuous MSDS efficiently couples microwaves to a single-phase, pressurized, flowing water stream that is rapidly heated above 150 C. Under these conditions, water is rapidly sterilized. Endotoxins, significant biological toxins that originate from the cell walls of gram-negative bacteria and which represent another defining MGW requirement, are also deactivated (i.e., depyrogenated) albeit more slowly, with such deactivation representing a more difficult challenge than sterilization. Several innovations culminated in the successful MSDS prototype design. The most significant is the antenna-directed microwave heating of a water stream flowing through a microwave sterilization chamber (MSC). Novel antenna designs were developed to increase microwave transmission efficiency. These improvements resulted in greater than 95-percent absorption of incident microwaves. In addition, incorporation of recuperative heat exchangers (RHxs) in the design reduced the microwave power required to heat a water stream flowing at 15 mL/min to 170 C to only 50 W. Further improvements in energy efficiency involved the employment of a second antenna to redirect reflected microwaves back into the MSC, eliminating the need for a water load and simplifying MSDS design. A quick connect (QC) is another innovation that can be sterilized and depyrogenated at temperature, and then cooled using a unique flow design, allowing collection of MGW at atmospheric pressure and 80 C. The final innovation was the use of in-line mixers incorporated in the flow path to disrupt laminar flow and increase contact time

  9. Comparison of microwave-assisted and heat reflux extraction techniques for the extraction of ten major compounds from Zibu Piyin Recipe using ultra high performance liquid chromatography with tandem mass spectrometry.

    PubMed

    Xu, Huiying; Zhan, Libin; Zhang, Lin

    2016-03-01

    Microwave-assisted extraction and efficient ultra-high performance liquid chromatography with triple quadrupole mass spectrometry were previously used to quickly extract and simultaneously quantify ginsenoside Rf, Ro, and Rd, 20(S)-ginsenoside-Rg2 , 20(R)-ginsenoside-Rg2 , tanshinone IIA, cryptotanshinone, dihydrotanshinone I, lithospermic acid, and osthole from Zibu Piyin Recipe. We here showed that heat reflux extraction provides higher extraction efficiency of these target compounds but is more time consuming. Chromatographic separation was achieved on an Agilent ZORBAX RRHD Eclipse Plus C18 column with a gradient mobile phase consisting of water/0.5% formic acid and acetonitrile at a flow rate of 0.2 mL/min, and detection was performed by positive and negative ion multiple-reaction monitoring mode. All analytes showed good linearity (r, 0.9989-0.9999) within the test range, with a limit of detection of 0.002-0.180 μg/mL. The overall intra- and interday variations of the ten compounds were ≤2.9%, and the accuracy was evaluated using a recovery test at three concentrations and was in the range 97.61-103.18% (RSD ≤ 4.25%). The analytical results showed remarkable differences in the concentrations of the ten compounds extracted from Zibu Piyin Recipe by microwave-assisted extraction and heat reflux extraction. These findings provide important information for determining the quality of Zibu Piyin Recipe. PMID:26749162

  10. Microwave sintering of large alumina bodies

    SciTech Connect

    Blake, R.D.; Katz, J.D.

    1993-05-01

    The application of microwaves as an energy source for materials processing of large alumina bodies at elevated temperatures has been limited to date. Most work has concerned itself with small laboratory samples. The nonuniformity of the microwave field within a cavity subjects large alumina bodies to areas of concentrated energy, resulting in uneven heating and subsequent cracking. Smaller bodies are not significantly affected by field nonuniformity due to their smaller mass. This work will demonstrate a method for microwave sintering of large alumina bodies while maintaining their structural integrity. Several alumina configurations were successfully sintered using a method which creates an artificial field or environment within the microwave cavity.

  11. Microwave sintering of large alumina bodies

    SciTech Connect

    Blake, R.D.; Katz, J.D.

    1993-01-01

    The application of microwaves as an energy source for materials processing of large alumina bodies at elevated temperatures has been limited to date. Most work has concerned itself with small laboratory samples. The nonuniformity of the microwave field within a cavity subjects large alumina bodies to areas of concentrated energy, resulting in uneven heating and subsequent cracking. Smaller bodies are not significantly affected by field nonuniformity due to their smaller mass. This work will demonstrate a method for microwave sintering of large alumina bodies while maintaining their structural integrity. Several alumina configurations were successfully sintered using a method which creates an artificial field or environment within the microwave cavity.

  12. Extraction of Maltol from Fraser Fir: A Comparison of Microwave-Assisted Extraction and Conventional Heating Protocols for the Organic Chemistry Laboratory

    ERIC Educational Resources Information Center

    Koch, Andrew S.; Chimento, Clio A.; Berg, Allison N.; Mughal, Farah D.; Spencer, Jean-Paul; Hovland, Douglas E.; Mbadugha, Bessie; Hovland, Allan K.; Eller, Leah R.

    2015-01-01

    Two methods for the extraction of maltol from Fraser fir needles are performed and compared in this two-week experiment. A traditional benchtop extraction using dichloromethane is compared to a microwave-assisted extraction using aqueous ethanol. Students perform both procedures and weigh the merits of each technique. In doing so, students see a…

  13. Ligand-free Pd-catalyzed and copper-assisted C-H arylation of quinazolin-4-ones with aryl iodides under microwave heating.

    PubMed

    Laclef, Sylvain; Harari, Marine; Godeau, Julien; Schmitz-Afonso, Isabelle; Bischoff, Laurent; Hoarau, Christophe; Levacher, Vincent; Fruit, Corinne; Besson, Thierry

    2015-04-01

    A microwave-assisted method for the palladium-catalyzed direct arylation of quinazolin-4-one has been developed under copper-assistance. This method is applicable to a wide range of aryl iodides and substituted (2H)-quinazolin-4-ones. This protocol provides a simple and efficient way to synthesize biologically relevant 2-arylquinazolin-4-one backbones. PMID:25781369

  14. Microwave superheaters for fusion

    SciTech Connect

    Campbell, R.B.; Hoffman, M.A.; Logan, B.G.

    1987-10-16

    The microwave superheater uses the synchrotron radiation from a thermonuclear plasma to heat gas seeded with an alkali metal to temperatures far above the temperature of material walls. It can improve the efficiency of the Compact Fusion Advanced Rankine (CFAR) cycle described elsewhere in these proceedings. For a proof-of-principle experiment using helium, calculations show that a gas superheat ..delta..T of 2000/sup 0/K is possible when the wall temperature is maintained at 1000/sup 0/K. The concept can be scaled to reactor grade systems. Because of the need for synchrotron radiation, the microwave superheater is best suited for use with plasmas burning an advanced fuel such as D-/sup 3/He. 5 refs.

  15. Microwave-assisted FLP-catalyzed hydrogenations.

    PubMed

    Tussing, S; Paradies, J

    2016-03-30

    FLP-catalyzed hydrogenations of 15 substrates were compared using microwave irradiation and conventional heating. The direct comparison revealed that a rate acceleration of up to 2.5 was achieved in the presence of microwaves. This heating method is particularly promising for the hydrogenation of nitrogen-containing heterocycles. Acridine, quinines and especially 1-methyl indole were reduced very efficiently under mild conditions and only 4 bar hydrogen pressure in high yields. PMID:26580129

  16. Microwavable thermal energy storage material

    DOEpatents

    Salyer, Ival O.

    1998-09-08

    A microwavable thermal energy storage material is provided which includes a mixture of a phase change material and silica, and a carbon black additive in the form of a conformable dry powder of phase change material/silica/carbon black, or solid pellets, films, fibers, moldings or strands of phase change material/high density polyethylene/ethylene-vinyl acetate/silica/carbon black which allows the phase change material to be rapidly heated in a microwave oven. The carbon black additive, which is preferably an electrically conductive carbon black, may be added in low concentrations of from 0.5 to 15% by weight, and may be used to tailor the heating times of the phase change material as desired. The microwavable thermal energy storage material can be used in food serving applications such as tableware items or pizza warmers, and in medical wraps and garments.

  17. Microwavable thermal energy storage material

    DOEpatents

    Salyer, I.O.

    1998-09-08

    A microwavable thermal energy storage material is provided which includes a mixture of a phase change material and silica, and a carbon black additive in the form of a conformable dry powder of phase change material/silica/carbon black, or solid pellets, films, fibers, moldings or strands of phase change material/high density polyethylene/ethylene vinyl acetate/silica/carbon black which allows the phase change material to be rapidly heated in a microwave oven. The carbon black additive, which is preferably an electrically conductive carbon black, may be added in low concentrations of from 0.5 to 15% by weight, and may be used to tailor the heating times of the phase change material as desired. The microwavable thermal energy storage material can be used in food serving applications such as tableware items or pizza warmers, and in medical wraps and garments. 3 figs.

  18. Enhanced Microwave Hyperthermia of Cancer Cells with Fullerene.

    PubMed

    Sun, Mingrui; Kiourti, Asimina; Wang, Hai; Zhao, Shuting; Zhao, Gang; Lu, Xiongbin; Volakis, John L; He, Xiaoming

    2016-07-01

    Hyperthermia generated with various energy sources including microwave has been widely studied for cancer treatment. However, the potential damage due to nontargeted heating of normal tissue is a major hurdle to its widespread application. Fullerene is a potential agent for improving cancer therapy with microwave hyperthermia but is limited by its poor solubility in water for biomedical applications. Here we report a combination therapy for enhanced cancer cell destruction by combining microwave heating with C60-PCNPs consisting of fullerene (C60) encapsulated in Pluronic F127-chitosan nanoparticles (PCNPs) with high water solubility. A cell culture dish integrated with an antenna was fabricated to generate microwave (2.7 GHz) for heating PC-3 human prostate cancer cells either with or without the C60-PCNPs. The cell viability data show that the C60-PCNPs alone have minimal cytotoxicity. The combination of microwave heating and C60-PCNPs is significantly more effective than the microwave heating alone in killing the cancer cells (7.5 versus 42.2% cell survival). Moreover, the combination of microwave heating and C60-PCNPs is significantly more destructive to the cancer cells than the combination of simple water-bath heating (with a similar thermal history to microwave heating) and C60-PCNPs (7.5 versus 32.5% survival) because the C60 in the many nanoparticles taken up by the cells can absorb the microwave energy and convert it into heat to enhance heating inside the cells under microwave irradiation. These data suggest the great potential of targeted heating via fullerene for enhanced cancer treatment by microwave hyperthermia. PMID:27195904

  19. Microwave experiments on Prairie View Rotamak

    SciTech Connect

    Zhou, R. J.; Xu, M.; Huang, Tian-Sen

    2015-05-15

    A 6 kW/2.45 GHz microwave system has been added on Prairie View Rotamak, and a series of experiments with microwave heating in both O-mode and X-mode configurations have been performed. Effective ionization of hydrogen in the two configurations is observed when filling pressure of the hydrogen gas is under p{sub f}=0.1 Pa. Clear oscillations in plasma current I{sub p} and magnetic field B{sub R} are excited when microwaves are injected into plasma in the X-mode configuration. The higher the injected microwave power, the sooner the emergence of the magnetic oscillations in B{sub R}, which implies the microwave may have decreased the elongation of the plasma. In the experiments, the efficiency of the current drive mechanism due to the injected microwave is about 0.2 kA/kW.

  20. Microwave processing of ceramic oxide filaments

    SciTech Connect

    Vogt, G.J.; Katz, J.D.

    1995-05-01

    The objective of the microwave filament processing project is to develop microwave techniques at 2.45 GHZ to manufacture continuous ceramic oxide filaments. Microwave processing uses the volumetric absorption of microwave power in oxide filament tows to drive off process solvents, to burn out organic binders, and to sinter the dried fibers to produce flexible, high-strength ceramic filaments. The technical goal is to advance filament processing technology by microwave heating more rapidly with less energy and at a lower cost than conventional processing, but with the same quality as conventional processing. The manufacturing goal is to collaborate with the 3M Company, a US manufacturer of ceramic oxide filaments, to evaluate the technology using a prototype filament system and to transfer the microwave technology to the 3M Company.

  1. COAL DESULFURIZATION USING MICROWAVE ENERGY

    EPA Science Inventory

    The report describes the use of microwave energy and NaOH to remove pyritic and organic sulfur from several U.S. coals. Exposure times on the order of 1 minute at 1 atmosphere of inert gas can remove up to 85% of the sulfur with little or no loss in heating value of the coal. Dat...

  2. Microwave Combustion and Sintering Without Isostatic Pressure

    SciTech Connect

    Ebadian, M.A.; Monroe, N.D.H.

    1998-10-20

    This investigation involves a study of the influence of key processing parameters on the heating of materials using microwave energy. Selective and localized heating characteristics of microwaves will be utilized in the sintering of ceramics without hydrostatic pressure. In addition, combustion synthesis will be studied for the production of powders, carbides, and nitrides by combining two or more solids or a solid and a gas to form new materials. The insight gained from the interaction of microwaves with various materials will be utilized in the mobilization and subsequent redeposition of uranium.

  3. Method for Processing Lunar Regolith Using Microwaves

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B.; Steinfeld, David E.

    2013-01-01

    A paper describes a method of using microwave heating experiments on lunar simulants to determine the mechanism that causes lunar regolith to be such an excellent microwave absorber. The experiments initially compared the effects of sharp particle edges to round particle edges on the heating curves. For most compositions, sharp particle edged samples were more effective in being heated by microwaves than round particle edged materials. However, the experiments also showed an unexpected effect for both types of particles. Upon heating the sample surface above 400 C, the sample experienced some sort of internal structure change that caused it to heat much more efficiently. This enhancement may be associated with the unique microwave volumetric heating that can produce a large temperature gradient within the sample leading to melting of some components at the center of the sample. This new effect that may also be happening in lunar regolith samples is probably the cause of the previously observed enhanced heating of a sample of lunar regolith. Properly designed microwave applicators could heat and solidify the lunar regolith to form roads and building blocks for structures needed on the Moon

  4. Transcatheter Microwave Antenna

    NASA Technical Reports Server (NTRS)

    Arndt, Dickey G. (Inventor); Carl, James R. (Inventor); Ngo, Phong (Inventor); Raffoul, George W. (Inventor)

    2001-01-01

    A method, simulation, and apparatus are provided that are highly suitable for treatment of benign prostatic hyperplasia (BPH). A catheter is disclosed that includes a small diameter disk loaded monopole antenna surrounded by fusion material having a high heat of fusion and a melting point preferably at or near body temperature. Microwaves from the antenna heat prostatic tissue to promote necrosing of the prostatic tissue that relieves the pressure of the prostatic tissue against the urethra as the body reabsorbs the necrosed or dead tissue. The fusion material keeps the urethra cool by means of the heat of fusion of the fusion material. This prevents damage to the urethra while the prostatic tissue is necrosed. A computer simulation is provided that can be used to predict the resulting temperature profile produced in the prostatic tissue. By changing the various control features of the catheter and method of applying microwave energy a temperature profile can be predicted and produced that is similar to the temperature profile desired for the particular patient.

  5. Microwave sintering of single plate-shaped articles

    DOEpatents

    Katz, Joel D.; Blake, Rodger D.

    1995-01-01

    Apparatus and method for high temperature sintering of plate-shaped articles of alumina, magnesia, silica, yttria, zirconia, and mixtures thereof using microwave radiation. An article is placed within a sintering structure located within a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled.

  6. Microwave sintering of single plate-shaped articles

    DOEpatents

    Katz, J.D.; Blake, R.D.

    1995-07-11

    Apparatus and method are disclosed for high temperature sintering of plate-shaped articles of alumina, magnesia, silica, yttria, zirconia, and mixtures thereof using microwave radiation. An article is placed within a sintering structure located within a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled. 2 figs.

  7. Microwave plasma synthesis of lanthanide zirconates from microwave transparent oxides.

    PubMed

    Chou, Yi-Hsin; Hondow, Nicole; Thomas, Chris I; Mitchell, Robert; Brydson, Rik; Douthwaite, Richard E

    2012-02-28

    Lanthanide zirconate phases Ln(2)Zr(2)O(7) and Ln(4)Zr(3)O(12) (Ln = Y, La, Gd, Dy, Ho, Yb) have been prepared using a microwave induced plasma methodology, which allows rapid synthesis using materials which do not couple directly with microwaves at room temperature. We describe the measurement of heating profiles of the precursor binary metal oxides which can be used to identify conditions conducive to the synthesis of more complex oxides. Uncontrolled heating which can be a feature of microwave synthesis of ceramics is not observed, allowing reproducible synthesis. Conventionally these phases are prepared at >1400 °C over hours or days and are being investigated for applications including the immobilisation of nuclear waste where rapid processing is important. Using the microwave plasma method, phase-pure materials have been prepared in minutes. Furthermore, it is clear that Ln(2)Zr(2)O(7) and Ln(4)Zr(3)O(12) also exhibit significant plasma-promoted dielectric heating (e.g. >2200 °C for Dy(4)Zr(3)O(12)) which is typically greater than either of the respective precursors, thus providing a driving force to rapidly complete the reaction. PMID:22215067

  8. Microwave continuous sterilization of injection ampoules.

    PubMed

    Sasaki, K; Honda, W; Shimizu, K; Iizima, K; Ehara, T; Okuzawa, K; Miyake, Y

    1996-01-01

    A new microwave continuous sterilizer (MWS) for applying microwave dielectric heating as an alternative to an autoclave was developed. The developmental objectives of the MWS were: 1. Achieving sufficient sterilization for the drugs containing heat-sensitive ingredients. 2. Measuring and recording sterilization temperature of each ampoule. 3. Ensuring automatic continuous operation and linkage with the preceding and following machines in an injection ampoule production process. The temperature of the drug solution in an ampoule was heated to 140 degrees C within about 30 seconds by the MWS. Target F0 value is achieved through the maintaining heater to maintain the target temperature for 12 seconds. Ampoules are cooled with air and water after completion of heating. The MWS is capable of processing 150 ampoules per minute. The newly developed techniques which minimized temperature distribution of heated ampoule solution were: 1. Microwave irradiation in a direction opposite to the direction of ampoules transportation. 2. Microwave irradiation in the lower part of ampoule solution (i.e., heating up the drug solution by thermal convection.) 3. Microwave power control by feedback of measured temperatures. 4. Heating rate control corresponding to the dielectric property of ampoule solution. The drug stability test was performed using 3% pyridoxamine phosphate solution, and the inactivation of spores in 3% pyridoxamine phosphate solution was examined using Bacillus stearothermophilus ATCC 7953 spores. The MWS was proved to have an adequate efficiency of sterilization with less chemical degradation of the contents than an autoclave. PMID:8696781

  9. Microwave treatment of vulcanized rubber

    DOEpatents

    Wicks, George G.; Schulz, Rebecca L.; Clark, David E.; Folz, Diane C.

    2002-07-16

    A process and resulting product is provided in which a vulcanized solid particulate, such as vulcanized crumb rubber, has select chemical bonds broken by microwave radiation. The direct application of microwaves in combination with uniform heating of the crumb rubber renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger particle sizes and/or loading levels of the treated crumb rubber can be used in new rubber mixtures to produce recycled composite products with good properties.

  10. Remarks on various applications of microwave energy.

    PubMed

    Bélanger, Jacqueline M R; Paré, J R Jocelyn; Poon, Oliver; Fairbridge, Craig; Ng, Siauw; Mutyala, Sateesh; Hawkins, Randall

    2008-01-01

    Microwave energy is an alternative energy source that is receiving a considerable amount of attention from researchers for a wide spectrum of applications. The fundamentally different method of transferring energy from the source to the sample is the main benefit of utilizing microwave energy; by directly delivering energy to microwave-absorbing materials, conventional issues such as long heating periods, thermal gradients, and energy lost to the system environment can be minimized or avoided. Furthermore, the penetrating capacity of microwave allows volumetric heating of samples. These attributes of microwave energy make utilizing it very attractive for industrial applications as an alternative to conventional processing methods. The reality is otherwise however, and limited literature is found in any given area of work. Despite the lack of focus, in most published cases, the utilization of microwave energy has produced improved results compared to conventional methods with reduced heating times or reaction temperatures. This review provides a general overview of reported applications of microwave energy in the open literature. It also attempts to summarize the results obtained for various common uses and highlights some applications that have not gathered as much attention as anticipated. PMID:19227061

  11. Thiazolidin-4-one formation. Mechanistic and synthetic aspects of the reaction of imines and mercaptoacetic acid under microwave and conventional heating.

    PubMed

    Bolognese, Adele; Correale, Gaetano; Manfra, Michele; Lavecchia, Antonio; Novellino, Ettore; Barone, Vincenzo

    2004-10-01

    Microwave irradiation of a mixture of benzylidene-anilines and mercaptoacetic acid in benzene gives 1,3-thiazolidin-4-ones in very high yield (65-90%), whereas the same reaction performed through using the conventional method, at reflux temperature, requires a much longer time and gives a much lower yield (25-69%). This difference seems to be due to some intermediates and by-products formed during the conventional reaction. On the basis of 1H NMR studies, two different mechanisms, acting in benzene and in DMF, respectively, have been hypothesized for the thiazolidin-4-one system formation. PMID:15455154

  12. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1989-01-01

    This paper discusses the following topics on microwave processing of ceramics: Microwave-material interactions; anticipated advantage of microwave sintering; ceramic sintering; and ceramic joining. 24 refs., 4 figs. (LSP)

  13. Industrial scale microwave processing of tomato juice using a novel continuous microwave system.

    PubMed

    Stratakos, Alexandros Ch; Delgado-Pando, Gonzalo; Linton, Mark; Patterson, Margaret F; Koidis, Anastasios

    2016-01-01

    This study evaluated the effect of an industrial scale continuous flow microwave volumetric heating system in comparison to conventional commercial scale pasteurisation for the processing of tomato juice in terms of physicochemical properties, microbial characteristics and antioxidant capacity. The effect against oxidative stress in Caco-2 cells, after in vitro digestion was also investigated. Physicochemical and colour characteristics of juices were very similar between technologies and during storage. Both conventional and microwave pasteurisation inactivated microorganisms and kept them in low levels throughout storage. ABTS[Symbol: see text](+) values, but not ORAC, were higher for the microwave pasteurised juice at day 0 however no significant differences between juices were observed during storage. Juice processed with the microwave system showed an increased cytoprotective effect against H2O2 induced oxidation in Caco-2 cells. Organoleptic analysis revealed that the two tomato juices were very similar. The continuous microwave volumetric heating system appears to be a viable alternative to conventional pasteurisation. PMID:26213019

  14. Evidence for non-thermal microwave effects using single and multimode hybrid conventional/microwave systems.

    PubMed

    Binner, Jon; Vaidhyanathan, Bala; Wang, Jianxin; Price, Duncan; Reading, Mike

    2008-01-01

    Clear evidence for the microwave effect has been observed during experiments in which a variety of materials have been heated using experimental systems that allowed both conventional and conventional-microwave hybrid heating. A hybrid single mode cavity has been used to investigate the microwave effect during phase changes in silver iodide, barium titanate and benzil, whilst a hybrid multimode cavity has been used to investigate the microwave effect during sintering and annealing of a range of ceramic materials with different dielectric properties. Although evidence for the microwave effect was not found in every case, where it was found the results could not be explained purely in terms of temperature gradients within the materials. PMID:19227076

  15. The microwave effects on the properties of alumina at high frequencies of microwave sintering

    NASA Astrophysics Data System (ADS)

    Sudiana, I. Nyoman; Mitsudo, Seitaro; Sako, Katsuhide; Inagaki, Shunsuke; Ngkoimani, La Ode; Usman, Ida; Aripin, H.

    2016-03-01

    Microwave sintering of materials has attracted much research interest because of its significant advantages (e.g. reduced sintering temperatures and soaking times) over the conventional heating. Most researchers compared processes that occurred during the microwave and conventional heating at the same temperature and time. The enhancements found in the former method are indicated as a `non-thermal effect` which is usually used for explaining the phenomena in microwave processing. Numerous recent studies have been focused on the effect to elucidate the microwave interaction mechanism with materials. Moreover, recent progress on microwave sources such as gyrotrons has opened the possibility for processing materials by using a higher microwave frequency. Therefore, the technology is expected to exhibit a stronger non-thermal effect. This paper presents results from a series of experiments to study the non-thermal effect on microwave sintered alumina. Sintering by using a wide rage of microwave frequencies up to 300 GHz as well as a conventional furnace was carried out. The linear shrinkages of samples for each sintering method were measured. Pores and grains taken from scanning electron microstructure (SEM) images of cut surfaces were also examined. The results of a comparative study of the shrinkages and microstructure evolutions of the sintered samples under annealing in microwave heating systems and in an electric furnace were analyzed. A notably different behavior of the shrinkages and microstructures of alumina after being annealed was found. The results suggested that microwave radiations provided an additional force for mass transports. The results also indicated that the sintering process depended on microwave frequencies.

  16. Microwave Technology--Applications in Chemical Synthesis

    EPA Science Inventory

    Microwave heating, being specific and instantaneous, is unique and has found a place for expeditious chemical syntheses. Specifically, the solvent-free reactions are convenient to perform and have advantages over the conventional heating protocols as summarized in the previous se...

  17. Microwave techniques for physical property measurements

    NASA Technical Reports Server (NTRS)

    Barmatz, M.

    1993-01-01

    Industrial processing of metals and ceramics is now being streamlined by the development of theoretical models. High temperature thermophysical properties of these materials are required to successfully apply these theories. Unfortunately, there is insufficient experimental data available for many of these properties, particularly in the molten state. Microwave fields can be used to measure specific heat, thermal diffusivity, thermal conductivity and dielectric constants at high temperatures. We propose to (1) develop a microwave flash method (analogous to the laser flash technique) that can simultaneously measure the thermal diffusivity and specific heat of insulators and semiconductors at high temperatures, (2) an appropriate theory and experimental apparatus to demonstrate the measurement of the specific heat of a metal using a new microwave ac specific heat technique, and (3) experimental methods for noncontact measurement of the real and imaginary dielectric constants.

  18. Microwave Treatment of Prostate Cancer and Hyperplasia

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey; Ngo, Phong; Carl, J. R.; Raffoul, George

    2005-01-01

    Microwave ablation in the form of microwave energy applied to a heart muscle by a coaxial catheter inserted in a vein in the groin area can be used to heat and kill diseased heart cells. A microwave catheter has been developed to provide deep myocardial ablation to treat ventricular tachycardia by restoring appropriate electrical activity within the heart and eliminating irregular heartbeats. The resulting microwave catheter design, which is now being developed for commercial use in treating ventricular tachycardia, can be modified to treat prostate cancer and benign prostatic hyperplasia (BPH). Inasmuch as the occurrence of BPH is increasing currently 350,000 operations per year are performed in the United States alone to treat this condition this microwave catheter has significant commercial potential.

  19. Spanish activities (research and industrial applications) in the field of microwave material treatment

    SciTech Connect

    Catala Civera, J.M.; Reyes Davo, E.R. de los

    1996-12-31

    The GCM (Microwave Heating Group) within the Communications Department at the Technical University of Valencia is dedicated to the study of microwaves and their use in the current industrial processes in the Valencian Community and in Spain. To this end, a microwave heating laboratory has been developed and the benefits of incorporating microwave technologies into current industrial processes have been demonstrated. In this paper some of the industrial applications which are being investigated are presented.

  20. Development of a microwave clothes dryer. Interim report II

    SciTech Connect

    Smith, R.D.; Gerling, J.E.

    1994-07-01

    The objective of the project is to investigate the microwave drying of clothes and to produce a database for use by interested parties, including appliance manufacturers, in designing and developing microwave clothes dryers. This is an interim report covering 1992 activities. Performance of a research model of a microwave dryer was compared to that of a conventional (top-of-the-line) electric dryer. Drying time was reduced by 58%; superior fabric care was demonstrated on fine fabrics because of the low drying temperatures; and efficiency was increased 18%. Microwaves penetrate the clothes and heat the water molecules directly while conventional heat energy must be conducted through the clothes to heat the water. A flow of heated air conducts the water vapor away from the clothes. Conventional metal buttons and zippers do not heat greatly in the 2,450 MHz microwave field but bobby pins, bread ties and nails heat enough to damage clothes. That heating has been eliminated by switching to the 915-MHz microwave frequency. Metallized threads may still constitute a heating problem. Based upon results from tests of the research model, a prototype has been designed and three units have been constructed. One unit is retained for laboratory testing while the other two will be shipped to two major appliance manufacturers for evaluations in their laboratories. Consumer panels generally liked the high speed, fabric care and improved efficiency of the microwave dryer but were concerned about the higher first cost.

  1. A phantom system for microwave treatment of intraocular tumors.

    PubMed

    Finger, P T; Selkin, R; Grabczyk, J; Fetter, R W

    1993-01-01

    A gel-block system was developed to illustrate heating patterns induced by ophthalmic microwave applicators. A heat-sensitive liquid crystal card was affixed as to bisect a Lucite box. The box was then filled with a clear tissue equivalent polyacrylamide gel. It was found that semicircular heating patterns were generated within the gel. These patterns were visualized by placing one of the dish-shaped ophthalmic microwave applicators on top of the polyacrylamide gel and the heat-sensitive liquid crystal card. An antenna was then placed in the gel and behind the card. Microwave energy was sent through the card and into the gel. This demonstrated the relatively homogeneous and roughly circular heating pattern produced at the applicator's surface. A combination of these profiles led to construction of a three-dimensional, dome-shaped model of heating, as provided by this microwave antenna design. PMID:8460282

  2. Microwave Treatment for Cardiac Arrhythmias

    NASA Technical Reports Server (NTRS)

    Hernandez-Moya, Sonia

    2009-01-01

    NASA seeks to transfer the NASA developed microwave ablation technology, designed for the treatment of ventricular tachycardia (irregular heart beat), to industry. After a heart attack, many cells surrounding the resulting scar continue to live but are abnormal electrically; they may conduct impulses unusually slowly or fire when they would typically be silent. These diseased areas might disturb smooth signaling by forming a reentrant circuit in the muscle. The objective of microwave ablation is to heat and kill these diseased cells to restore appropriate electrical activity in the heart. This technology is a method and apparatus that provides for propagating microwave energy into heart tissues to produce a desired temperature profile therein at tissue depths sufficient for thermally ablating arrhythmogenic cardiac tissue while preventing excessive heating of surrounding tissues, organs, and blood. A wide bandwidth double-disk antenna is effective for this purpose over a bandwidth of about six gigahertz. A computer simulation provides initial screening capabilities for an antenna such as antenna, frequency, power level, and power application duration. The simulation also allows optimization of techniques for specific patients or conditions. In comparison with other methods that involve direct-current pulses or radio frequencies below 1 GHz, this method may prove more effective in treating ventricular tachycardia. This is because the present method provides for greater control of the location, cross-sectional area, and depth of a lesion via selection of the location and design of the antenna and the choice of microwave power and frequency.

  3. Apparatus and method for microwave processing of materials

    DOEpatents

    Johnson, A.C.; Lauf, R.J.; Bible, D.W.; Markunas, R.J.

    1996-05-28

    Disclosed is a variable frequency microwave heating apparatus designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency heating apparatus is used in the method of the present invention to monitor the resonant processing frequency within the furnace cavity depending upon the material, including the state thereof, from which the workpiece is fabricated. The variable frequency microwave heating apparatus includes a microwave signal generator and a high-power microwave amplifier or a microwave voltage-controlled oscillator. A power supply is provided for operation of the high-power microwave oscillator or microwave amplifier. A directional coupler is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. 10 figs.

  4. Apparatus and method for microwave processing of materials

    DOEpatents

    Johnson, Arvid C.; Lauf, Robert J.; Bible, Don W.; Markunas, Robert J.

    1996-01-01

    A variable frequency microwave heating apparatus (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34) for testing or other selected applications. The variable frequency heating apparatus (10) is used in the method of the present invention to monitor the resonant processing frequency within the furnace cavity (34) depending upon the material, including the state thereof, from which the workpiece (36) is fabricated. The variable frequency microwave heating apparatus (10) includes a microwave signal generator (12) and a high-power microwave amplifier (20) or a microwave voltage-controlled oscillator (14). A power supply (22) is provided for operation of the high-power microwave oscillator (14) or microwave amplifier (20). A directional coupler (24) is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity (34). A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

  5. Continuous microwave regeneration apparatus for absorption media

    SciTech Connect

    Smith, D.D.

    1999-09-07

    A method and apparatus are disclosed for continuously drying and regenerating ceramic beads for use in process gas moisture drying operations such as glove boxes. A microwave energy source is coupled to a process chamber to internally heat the ceramic beads and vaporize moisture contained therein. In a preferred embodiment, the moisture laden ceramic beads are conveyed toward the microwave source by a screw mechanism. The regenerated beads flow down outside of the screw mechanism and are available to absorb additional moisture.

  6. Continuous microwave regeneration apparatus for absorption media

    DOEpatents

    Smith, Douglas D.

    1999-01-01

    A method and apparatus for continuously drying and regenerating ceramic beads for use in process gas moisture drying operations such as glove boxes. A microwave energy source is coupled to a process chamber to internally heat the ceramic beads and vaporize moisture contained therein. In a preferred embodiment, the moisture laden ceramic beads are conveyed toward the microwave source by a screw mechanism. The regenerated beads flow down outside of the screw mechanism and are available to absorb additional moisture.

  7. Processing of fresh palm fruits using microwaves.

    PubMed

    Chow, Mee Chin; Ma, Ah Ngan

    2007-01-01

    Microwave heating was determined in this study to be suitable for the detachment and drying of palm fruits from whole bunches, cut bunches and spikelets. Microwave treatment of the palm fruits was able to attain the objectives of conventional fresh palm fruits sterilization processeses such as fruit softening, nut conditioning and halting of enzymatic lipolysis. Palm oil and kernel oil solvent extracted respectively from the microwave treated whole fruits and kernel were found to have a good quality of low free fatty acid content. This technology, together with the solvent extraction of the dehydrated fruits, may have the potential to be a continuous, dry and clean technology for palm oil milling. PMID:17645207

  8. Feasibility and Performance of the Microwave Thermal Rocket Launcher

    NASA Astrophysics Data System (ADS)

    Parkin, Kevin L. G.; Culick, Fred E. C.

    2004-03-01

    Beamed-energy launch concepts employing a microwave thermal thruster are feasible in principle, and microwave sources of sufficient power to launch tons into LEO already exist. Microwave thermal thrusters operate on an analogous principle to nuclear thermal thrusters, which have experimentally demonstrated specific impulses exceeding 850 seconds. Assuming such performance, simple application of the rocket equation suggests that payload fractions of 10% are possible for a single stage to orbit (SSTO) microwave thermal rocket. We present an SSTO concept employing a scaled X-33 aeroshell. The flat aeroshell underside is covered by a thin-layer microwave absorbent heat-exchanger that forms part of the thruster. During ascent, the heat-exchanger faces the microwave beam. A simple ascent trajectory analysis incorporating X-33 aerodynamic data predicts a 10% payload fraction for a 1 ton craft of this type. In contrast, the Saturn V had 3 non-reusable stages and achieved a payload fraction of 4%.

  9. Microwave Regenerable Air Purification Device

    NASA Technical Reports Server (NTRS)

    Atwater, James E.; Holtsnider, John T.; Wheeler, Richard R., Jr.

    1996-01-01

    The feasibility of using microwave power to thermally regenerate sorbents loaded with water vapor, CO2, and organic contaminants has been rigorously demonstrated. Sorbents challenged with air containing 0.5% CO2, 300 ppm acetone, 50 ppm trichloroethylene, and saturated with water vapor have been regenerated, singly and in combination. Microwave transmission, reflection, and phase shift has also been determined for a variety of sorbents over the frequency range between 1.3-2.7 GHz. This innovative technology offers the potential for significant energy savings in comparison to current resistive heating methods because energy is absorbed directly by the material to be heated. Conductive, convective and radiative losses are minimized. Extremely rapid heating is also possible, i.e., 1400 C in less than 60 seconds. Microwave powered thermal desorption is directly applicable to the needs of Advance Life Support in general, and of EVA in particular. Additionally, the applicability of two specific commercial applications arising from this technology have been demonstrated: the recovery for re-use of acetone (and similar solvents) from industrial waste streams using a carbon based molecular sieve; and the separation and destruction of trichloroethylene using ZSM-5 synthetic zeolite catalyst, a predominant halocarbon environmental contaminant. Based upon these results, Phase II development is strongly recommended.

  10. Technical and Engineering Feasibility Study of the Vitrification of Plutonium-Bearing Sludges at the Krasnoyarsk Mining and Chemical Combine by Means of Microwave Heating

    SciTech Connect

    Revenko, Y.A.; Kudinov, K.G.; Tretyakov, A.A.; Vassilyev, A.V.; Borisov, G.B.; Nazarov, A.V.; Aloy, A.S.; Shvedov, A.A.; Gusakov, B.V.; Jardine, L.J.

    2000-03-03

    This engineering feasibility study compared three possible technical options and their economic viability of processing plutonium-bearing sludges containing 0.6 MT of weapons-grade Pu accumulated at the Mining and Chemical Combine (MCC) at Krasnoyarsk. In Option 1, the baseline, the sludges are processed by extraction and purification of plutonium for storage using existing technologies, and the non-soluble radioactive residues generated in these processes undergo subsequent solidification by cementation. Options 2 and 3 involve the direct immobilization of plutonium-bearing sludges into a solid matrix (without any Pu extraction) using a microwave solidification process in a metal crucible to produce a glass, which is boron-silicate in Option 2 and phosphate glass in Option 3. In all three options, the solid radioactive waste end products will be placed in storage for eventual geologic disposal. Immobilization of residual plutonium into glass-like matrices provides both safer storage over the lifetime of the radionuclides and greater security against unauthorized access to stored materials than does the extraction and concentration of PuO{sub 2}, supporting our efforts toward non-proliferation of fissile materials. Although immobilization in boron-silicate glass appears now to be marginally preferable compared to the phosphate glass option, a number of technical issues remain to be assessed by further study to determine the preferable immobilization option.

  11. Fabrication and luminescent properties of Al2O3:Cr3 + microspheres via a microwave solvothermal route followed by heat treatment

    NASA Astrophysics Data System (ADS)

    Zhu, Zhenfeng; Liu, Dianguang; Liu, Hui; Du, Juan; Yu, Hongguang; Deng, Jie

    2012-06-01

    AlOOH:Cr3 + powders were synthesized via a microwave solvothermal route at 433 K for 30 min and were used as the precursor and template for the preparation of γ-Al2O3:Cr3 + by thermal transformation at 773 K for 2 h in air. The obtained γ-Al2O3 based powders were microspheres with an average diameter about 1.9 μm. Photoluminescence (PL) spectra showed that the Al2O3:Cr3 + particles presented a symmetric broad R band at 696 nm without appreciable splitting when excited at 462 nm. It is shown that the 0.04 mol% of doping concentration of Cr3 + ions in γ-Al2O3:Cr3 + is optimum. According to Dexter's theory, the critical distance between Cr3 + ions for energy transfer was determined to be 47.54 Å. Based on the corresponding PL spectrum, full width at half maximum (FWHM) of Al2O3:Cr3 + (0.04 mol%) was calculated to be 3.35 nm.

  12. Mechanism of microwave sterilization in the dry state.

    PubMed Central

    Jeng, D K; Kaczmarek, K A; Woodworth, A G; Balasky, G

    1987-01-01

    With an automated computerized temperature control and a specialized temperature measurement system, dry spores of Bacillus subtilis subsp. niger were treated with heat simultaneously in a convection dry-heat oven and a microwave oven. The temperature of the microwave oven was monitored such that the temperature profiles of the spore samples in both heat sources were nearly identical. Under these experimental conditions, we unequivocally demonstrated that the mechanism of sporicidal action of the microwaves was caused solely by thermal effects. Nonthermal effects were not significant in a dry microwave sterilization process. Both heating systems showed that a dwelling time of more than 45 min was required to sterilize 10(5) inoculated spores in dry glass vials at 137 degrees C. The D values of both heating systems were 88, 14, and 7 min at 117, 130, and 137 degrees C, respectively. The Z value was estimated to be 18 degrees C. PMID:3118807

  13. Microwave-enhanced thermal decontamination of soil

    SciTech Connect

    Kawala, Z.; Atamanczuk, T.

    1998-09-01

    Results of bench-scale and pilot-scale investigations on the remediation of contaminated sand and soil using microwave energy are presented. Microwave radiation penetrates the soil and heats water and contaminants. Developing vapors are withdrawn from the soil. The experiments suggest that microwave heating is an effective soil remediation technology. The process is rapid as compared to other methods, and its efficiency depends on the dielectric and physicochemical properties of the soil and the contaminant. It allows for the removal of volatile and semivolatile components, and it is especially effective in the case of polar compounds. In the presence of soil moisture, the removal of both polar and nonpolar compounds can be described quantitatively in terms of stream distillation. The remediation proceeds at a temperature not exceeding 100 C. It is of particular importance in the case of soil rich in organic matter, where too high a temperature could result in carbonization of humic substances. The remediation of trichloroethylene-contaminated sand in a pilot-scale microwave heating system simulating the in-situ process is also reported. The profiles of temperature and contaminant concentration in the remediation zone are presented. The pilot-scale investigations indicate a possibility of the use of microwave heating as an in-situ remediation technique. The use of inexpensive low-power generators for the supply of power to individual antennas may help to reduce costs and allow for an unconstrained design of the array of antennas in the ground.

  14. Circular Bioassay Platforms for Applications in Microwave-Accelerated Techniques

    PubMed Central

    Mohammed, Muzaffer; Clement, Travis C.; Aslan, Kadir

    2014-01-01

    In this paper, we present the design of four different circular bioassay platforms, which are suitable for homogeneous microwave heating, using theoretical calculations (i.e., COMSOL™ multiphysics software). Circular bioassay platforms are constructed from poly(methyl methacrylate) (PMMA) for optical transparency between 400–800 nm, has multiple sample capacity (12, 16, 19 and 21 wells) and modified with silver nanoparticle films (SNFs) to be used in microwave-accelerated bioassays (MABs). In addition, a small monomode microwave cavity, which can be operated with an external microwave generator (100 W), for use with the bioassay platforms in MABs is also developed. Our design parameters for the circular bioassay platforms and monomode microwave cavity during microwave heating were: (i) temperature profiles, (ii) electric field distributions, (iii) location of the circular bioassay platforms inside the microwave cavity, and (iv) design and number of wells on the circular bioassay platforms. We have also carried out additional simulations to assess the use of circular bioassay platforms in a conventional kitchen microwave oven (e.g., 900 W). Our results show that the location of the circular bioassay platforms in the microwave cavity was predicted to have a significant effect on the homogeneous heating of these platforms. The 21-well circular bioassay platform design in our monomode microwave cavity was predicted to offer a homogeneous heating pattern, where inter-well temperature was observed to be in between 23.72–24.13°C and intra-well temperature difference was less than 0.21°C for 60 seconds of microwave heating, which was also verified experimentally. PMID:25568813

  15. Microwave-assisted stripping of oil contaminated drill cuttings.

    PubMed

    Robinson, J P; Kingman, S W; Onobrakpeya, O

    2008-07-01

    The application of microwave heating technology to conventional gas stripping processes has been investigated in the remediation of contaminated drill cuttings. The technical feasibility and limitations of nitrogen and steam stripping processes are demonstrated, and it is shown that the combination of microwave heating with the stripping process offers a step change in performance. Order of magnitude improvements in processing time are shown for the microwave-assisted processes, as well as greatly improved levels of remediation. The mechanisms of contaminant removal are discussed, along with the phenomena which occur with microwave heating processes. The energy requirements of each of pure gas and microwave-assisted processes are also discussed, and the potential applications of each technology are highlighted relative to the overall remediation requirements. PMID:17433529

  16. Microwave-Assisted Synthesis of "N"-Phenylsuccinimide

    ERIC Educational Resources Information Center

    Shell, Thomas A.; Shell, Jennifer R.; Poole, Kathleen A.; Guetzloff, Thomas F.

    2011-01-01

    A microwave-assisted synthesis of "N"-phenylsuccinimide has been developed for the second-semester organic teaching laboratory. Utilizing this procedure, "N"-phenylsuccinimide can be synthesized in moderate yields (40-60%) by heating a mixture of aniline and succinic anhydride in a domestic microwave oven for four minutes. This technique reduces…

  17. Microwave Treatment for Cardiac Arrhythmias

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Carl, James R. (Inventor); Raffoul, George W. (Inventor); Pacifico, Antonio (Inventor)

    1999-01-01

    Method and apparatus are provided for propagating microwave energy into heart tissues to produce a desired temperature profile therein at tissue depths sufficient for thermally ablating arrhythmogenic cardiac tissue to treat ventricular tachycardia and other arrhythmias while preventing excessive heating of surrounding tissues, organs, and blood. A wide bandwidth double-disk antenna is effective for this purpose over a bandwidth of about six gigahertz. A computer simulation provides initial screening capabilities for an antenna such as antenna, frequency, power level, and power application duration. The simulation also allows optimization of techniques for specific patients or conditions. In operation, microwave energy between about 1 Gigahertz and 12 Gigahertz is applied to monopole microwave radiator having a surface wave limiter. A test setup provides physical testing of microwave radiators to determine the temperature profile created in actual heart tissue or ersatz heart tissue. Saline solution pumped over the heart tissue with a peristaltic pump simulates blood flow. Optical temperature sensors disposed at various tissue depths within the heart tissue detect the temperature profile without creating any electromagnetic interference. The method may be used to produce a desired temperature profile in other body tissues reachable by catheter such as tumors and the like.

  18. Transcatheter Antenna For Microwave Treatment

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Carl, James R. (Inventor); Raffoul, George W. (Inventor); Karasack, Vincent G. (Inventor); Pacifico, Antonio (Inventor); Pieper, Carl F. (Inventor)

    2000-01-01

    Method and apparatus are provided for propagating microwave energy into heart tissues to produce a desired temperature profile therein at tissue depths sufficient for thermally ablating arrhythmogenic cardiac tissue to treat ventricular tachycardia and other arrhythmias while preventing excessive heating of surrounding tissues, organs, and blood. A wide bandwidth double-disk antenna is effective for this purpose over a bandwidth of about six gigahertz. A computer simulation provides initial screening capabilities for an antenna such as antenna, frequency, power level, and power application duration. The simulation also allows optimization of techniques for specific patients or conditions. In operation, microwave energy between about 1 Gigahertz and 12 Gigahertz is applied to monopole microwave radiation having a surface wave limiter. A test setup provides physical testing of microwave radiators to determine the temperature profile created in actual heart tissue or ersatz heart tissue. Saline solution pumped over the heart tissue with a peristaltic pump simulates blood flow. Optical temperature sensors disposed at various tissue depths within the heart tissue detect the temperature profile without creating any electromagnetic interference. The method may he used to produce a desired temperature profile in other body tissues reachable by catheter such as tumors and the like.

  19. Thermoregulation in intense microwave fields

    SciTech Connect

    Michaelson, S.M.

    1981-10-01

    These studies clearly indicate the thermoregulatory capacity of the dog to withstand exposure to high microwave fields at specific absorption rates (SAR) of 3.7 and 6.1 W/kg. It appears that adequate thermoregulation takes place at an SAR of 3.7 W/kg but only transiently at 6.1 W/kg. These values, compared with the standardized resting metabolic rate of 3.29 W/kg (0.75), provide a basis for assessing the relationship of the thermal burden and thermo-regulatory disruption by microwaves in the dog. To elucidate the thermal potential of microwave exposure, it was helpful to conduct these exposures at various ambient temperatures in which the normal body temperature remained stable, thus permitting comparison of heat production and dissipation with our without microwaves. The zone of the thermal neutrality or thermoneutral zone of vasomotor activity, 22-26.5 deg C, where body temperature is regulated by changes in vasomotor tonus, fulfilled this requirement.

  20. Flash microwave synthesis of trevorite nanoparticles

    SciTech Connect

    Bousquet-Berthelin, C. Chaumont, D.; Stuerga, D.

    2008-03-15

    Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named 'lithium-ion' batteries. In this study, NiFe{sub 2}O{sub 4} was prepared by microwave induced thermohydrolysis. The obtained nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), BET method, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). All the results show that the microwave one-step flash synthesis leads in a very short time to NiFe{sub 2}O{sub 4} nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m{sup 2}/g). Thus, microwave heating appears as an efficient source of energy to produce quickly nanoparticles with complex composition as ferrite. - Graphical abstract: At the end of the 20th century, a new concept of battery was introduced, named 'Li ion', where electrodes are both lithium-storage materials. Compounds with a spinel structure are so investigated and microwave heating appears as an efficient source of energy to produce nanoparticles in a very short time and at low temperature, with controlled size (4-5 nm) and high specific area (240 m{sup 2}/g). Legend: Pictogram represents our original microwave reactor, the RAMO (French acronym of Reacteur Autoclave Micro-Onde), containing the reactants and submitted to the microwave irradiation. Multicolor candy represents obtained material.

  1. Microwave Ovens--Out of the Kitchen

    NASA Astrophysics Data System (ADS)

    Cresswell, Sarah L.; Haswell, Stephen J.

    2001-07-01

    We are all aware of the advantages cooking or heating meals in a microwave oven can offer, but we may be less familiar with what this technology brings to the field of chemistry. This paper reviews the applications of microwaves in the chemical laboratory, including their use in undergraduate laboratory classes. We show that microwave ovens have successfully made the transition from kitchens to laboratories and the story continues. Perhaps the greatest impact of microwaves in the laboratory over the past 20 years has been in analytical chemistry, where rapid and efficient heating of samples in closed vessels or flow-through systems has revolutionized sample preparation methodology. The use of microwaves in extraction procedures before chromatographic analysis has sharply reduced the total analysis time and has allowed larger numbers of samples to be analyzed. More recently microwave technology has expanded into other branches of chemistry and is now being used in the relatively new field of combinatorial chemistry for fast preparation of large numbers of similar compounds.

  2. Microwave combustion and sintering without isostatic pressure

    SciTech Connect

    Ebadian, M.A.

    1998-01-01

    In recent years interest has grown rapidly in the application of microwave energy to the processing of ceramics, composites, polymers, and other materials. Advances in the understanding of microwave/materials interactions will facilitate the production of new ceramic materials with superior mechanical properties. One application of particular interest is the use of microwave energy for the mobilization of uranium for subsequent redeposition. Phase III (FY98) will focus on the microwave assisted chemical vapor infiltration tests for mobilization and redeposition of radioactive species in the mixed sludge waste. Uranium hexachloride and uranium (IV) borohydride are volatile compounds for which the chemical vapor infiltration procedure might be developed for the separation of uranium. Microwave heating characterized by an inverse temperature profile within a preformed ceramic matrix will be utilized for CVI using a carrier gas. Matrix deposition is expected to commence from the inside of the sample where the highest temperature is present. The preform matrix materials, which include aluminosilicate based ceramics and silicon carbide based ceramics, are all amenable to extreme volume reduction, densification, and vitrification. Important parameters of microwave sintering such as frequency, power requirement, soaking temperature, and holding time will be investigated to optimize process conditions for the volatilization of uranyl species using a reactive carrier gas in a microwave chamber.

  3. Microwave peak absorption frequency of liquid

    NASA Astrophysics Data System (ADS)

    Han, Guangze; Chen, Mingdong

    2008-09-01

    Microwave-assisted extraction is a new effective method which has practical applications in many fields. Microwave heating is one of its physical mechanisms, and it also has the characteristic of selectivity. When the applied microwave frequency equals a certain absorption frequency of the material (or specific component), the material will intensively absorb microwave energy. This is also known as resonant absorption, and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work, dynamic hydrogen bond energy was included in molecular activation energy; with the liquid cell model, the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and relaxation time, the expression of microwave peak absorption frequency as a function of the material physical structure, rotational inertia and electrical dipole moment of molecules was established. These theoretical formulas were applied to water and benzene, and the calculated results agree fairly well with the experimental data. This work can not only deepen the study of the interaction between microwave and material, but also provide a possible guide for the experiment of microwave-assisted extraction.

  4. Microwave-assisted sample preparation of coal and coal fly ash for subsequent metal determination

    SciTech Connect

    Srogi, K.

    2007-01-15

    The aim of this paper is to review microwave-assisted digestion of coal and coal fly ash. A brief description of microwave heating principles is presented. Microwave-assisted digestion appears currently to be the most popular preparation technique, possibly due to the comparatively rapid sample preparation and the reduction of contamination, compared to the conventional hot-plate digestion methods.

  5. A Comparative Spectrophotometric Study Using Ferrozine and 1,10-Ortho-phenanthroline to Evaluate the Iron Redox Ratio (Fe(2+)/ΣFe) in Glass Prepared by Microwave Heating.

    PubMed

    Mandal, Biswajit; Sinha, Prasanta Kumar; Sen, Ranjan; Mandal, Ashis Kumar

    2016-01-01

    In the present study, Fe-doped barium borosilicate glass has been melted at 1250°C under microwave heating. The iron redox ratio (Fe(2+)/total Fe) in the glass is investigated by two spectrophotometric methods. A novel decomposition technique has been optimized to measure the ferrous oxidation state in glass. Ferrozine was chosen as a specific complexing reagent; it forms a deep violet color complex with Fe(2+) and has a broad absorbance peak centered at ∼562 nm. 1,10-ortho-phenanthroline develops an orange color complex with Fe(2+) (having an absorbance peak centered at ∼510 nm) and has been used to determine ferrous ion in glass. Both the methods are compared and the estimated redox ratio was found to be higher in the ferrozine method. The error limit of measurement has been determined as 0.012 and 0.023 for the ferrozine and 1,10-ortho-phenanthroline methods, respectively. PMID:27169658

  6. Bonding PMMA microfluidics using commercial microwave ovens

    NASA Astrophysics Data System (ADS)

    Toossi, A.; Moghadas, H.; Daneshmand, M.; Sameoto, D.

    2015-08-01

    In this paper, a novel low-cost, rapid substrate-bonding technique is successfully applied to polymethyl methacrylate (PMMA) microfluidics bonding for the first time. This technique uses a thin intermediate metallic microwave susceptor layer at the interface of the bonding site (microchannels) which produces localized heating required for bonding during microwave irradiation. The metallic susceptor pattern is designed using a multiphysics simulation model developed in ANSYS Multiphysics software (high-frequency structural simulation (HFSS) coupled with ANSYS-Thermal). In our experiments, the required microwave energy for bonding is delivered using a relatively inexpensive, widely accessible commercial microwave oven. Using this technique, simple PMMA microfluidics prototypes are successfully bonded and sealed in less than 35 seconds with a minimum measured bond strength of 1.375 MPa.

  7. Microwave induced fast pyrolysis of scrap rubber tires

    NASA Astrophysics Data System (ADS)

    Ani, Farid Nasir; Mat Nor, Nor Syarizan

    2012-06-01

    Pyrolysis is the thermal degradation of carbonaceous solid by heat in the absence of oxygen. The feedstocks, such as biomass or solid wastes are heated to a temperature between 400 and 600°C, without introducing oxygen to support the reaction. The reaction produces three products: gas, pyro-fuel oil and char. This paper presents the techniques of producing pyro-oil from waste tires, as well as investigation of the fuel properties suitable for diesel engine applications. In this study, microwave heating technique is employed to pyrolyse the used rubber tires into pyro-oil. Thermal treatment of as received used rubber tires is carried out in a modified domestic microwave heated fixed bed technology. It has been found that, rubber tires, previously used by various researchers, are poor microwave absorbers. Studies have shown that an appropriate microwave-absorbing material, such as biomass char or activated carbon, could be added to enhance the pyrolysis process; thus producing the pyro-oil. The characteristics of pyro-oil, as well as the effect of microwave absorber on its yield, are briefly described in this paper. The temperature profiles during the microwave heating process are also illustratively emphasized. The study provides a means of converting scrap tires into pyro-oil and pyrolytic carbon black production. The proposed microwave thermal conversion process therefore has the potentials of substantially saving time and energy.

  8. Interaction of Microwaves with Synthetic Type A Zeolite Containing Water

    NASA Astrophysics Data System (ADS)

    Tanaka, Masahiro; Takayama, Sadatsugu; Sano, Saburo

    2013-11-01

    A synthetic honeycomb type A zeolite adsorbent was regenerated through microwave irradiation in a single-mode cavity microwave at 2.46 GHz. The regeneration mechanism was investigated by comparing the heating properties, thermogravimetric properties, and dielectric properties of the synthetic zeolite samples. The hydrated zeolite sample was easily heated to over 200 °C, although a difference in the impedance matching frequency of only 0.01 GHz sharply reduced the maximum heating and increased the regeneration time. The adsorbed water in the hydrated zeolite initially acted as a heating agent by absorbing microwave energy, because the dielectric loss factor of water is higher than that of synthetic zeolite around 2.45 GHz. From 50 to 250 °C, the zeolite itself also absorbed microwave energy.

  9. Microwave-assisted 'greener' synthesis of organics and nanomaterials

    EPA Science Inventory

    Microwave selective heating techniques in conjunction with greener reaction media are dramatically reducing chemical waste and reaction times in several organic transformations and material synthesis. This presentation summarizes author’s own experience in developing MW-assisted ...

  10. Hydrogen recovery from extraterrestrial materials using microwave energy

    NASA Astrophysics Data System (ADS)

    Tucker, D. S.; Vaniman, D. T.; Anderson, J. L.; Clinard, F. W., Jr.; Feber, R. C., Jr.; Frost, H. M.; Meek, T. T.; Wallace, T. C.

    The feasibility of recovering hydrogen from extraterrestrial materials (lunar and Martian soils, asteroids) using microwave energy is presented. Reasons for harvesting and origins and locations of hydrogen are reviewed. Problems of hydrogen recovery are discussed in terms of hydrogen release characteristics and microwave coupling to insulating materials. From results of studies of hydrogen diffusivities (oxides, glasses) and tritium release (oxides) as well as studies of microwave coupling to ilmenite, alkali basalt and ceramic oxides it is concluded that using microwave heating in hydrogen recovery from extraterrestrial materials could be the basis for a workable process.

  11. Design of microwave vitrification systems for radioactive waste

    SciTech Connect

    White, T.L.; Wilson, C.T.; Schaich, C.R.; Bostick, T.L.

    1995-12-31

    Oak Ridge National Laboratory (ORNL) is involved in the research and development of high-power microwave heating systems for the vitrification of Department of Energy (DOE) radioactive sludges. Design criteria for a continuous microwave vitrification system capable of processing a surrogate filtercake sludge representative of a typical waste-water treatment operation are discussed. A prototype 915-MHz, 75-kW microwave vitrification system or ``microwave melter`` is described along with some early experimental results that demonstrate a 4 to 1 volume reduction of a surrogate ORNL filtercake sludge.

  12. Microwave measurement test results of circular waveguide components for electron cyclotron resonant heating (ECRH) of the Tandem Mirror Experiment-Upgrade (TMX-U)

    SciTech Connect

    Williams, C.W.; Rubert, R.R.; Coffield, F.E.; Felker, B.; Stallard, B.W.; Taska, J.

    1983-12-01

    Development of high-power components for electron cyclotron resonant heating (ECRH) applications requires extensive testing. In this paper we describe the high-power testing of various circular waveguide components designed for application on the Tandem Mirror Experiment-Upgrade (TMX-U). These include a 2.5-in. vacuum valve, polarizing reflectors, directional couplers, mode converters, and flexible waveguides. All of these components were tested to 200 kW power level with 40-ms pulses. Cold tests were used to determine field distribution. The techniques used in these tests are illustrated. The new high-power test facility at Lawrence Livermore National Laboratory (LLNL) is described and test procedures are discussed. We discuss the following test results: efficiency at high power of mode converters, comparison of high power vs low power for waveguide components, and full power tests of the waveguide system. We also explain the reasons behind selection of these systems for use on TMX-U.

  13. Parameters affecting the microwave-specific acceleration of a chemical reaction.

    PubMed

    Chen, Po-Kai; Rosana, Michael R; Dudley, Gregory B; Stiegman, A E

    2014-08-15

    Under appropriate conditions, significant microwave-specific enhancement of the reaction rate of an organic chemical reaction can be observed. Specifically, the unimolecular Claisen rearrangement of allyl p-nitrophenyl ether (ApNE) dissolved in naphthalene was studied under microwave heating and conventional convective (thermal) heating. Under constant microwave power, reaching a temperature of 185 °C, a 4-fold rate enhancement was observed in the microwave over that using convective heating; this means that the microwave reaction was proceeding at an effective temperature of 202 °C. Conversely, under constant temperature microwave conditions (200 °C), a negligible (∼1.5-fold) microwave-specific rate enhancement was observed. The largest microwave-specific rate enhancement was observed when a series of 300 W pulses, programmed for 145-175 °C and 85-155 °C cycles, where 2- and 9-fold rate enhancements, over what would be predicted by conventional thermal heating, was observed, respectively. The postulated origins of the microwave-specific effect are purely thermal and arise from selective heating of ApNE, a microwave-absorbing reactant in a nonabsorbing solvent. Under these conditions, excess heat is accumulated in the domains around the ApNE solute so that it experiences a higher effective temperature than the measured temperature of the bulk medium, resulting in an accelerated unimolecular rearrangement. PMID:25050921

  14. Microwave Radiometer (MWR) Handbook

    SciTech Connect

    Morris, VR

    2006-08-01

    The Microwave Radiometer (MWR) provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is essentially a sensitive microwave receiver. That is, it is tuned to measure the microwave emissions of the vapor and liquid water molecules in the atmosphere at specific frequencies.

  15. Microwave Workshop for Windows.

    ERIC Educational Resources Information Center

    White, Colin

    1998-01-01

    "Microwave Workshop for Windows" consists of three programs that act as teaching aid and provide a circuit design utility within the field of microwave engineering. The first program is a computer representation of a graphical design tool; the second is an accurate visual and analytical representation of a microwave test bench; the third is a more…

  16. Carbon nanotubes and microwaves: interactions, responses, and applications.

    PubMed

    Vázquez, Ester; Prato, Maurizio

    2009-12-22

    The interaction of microwaves with carbon nanotubes (CNTs) is an interesting topic for a variety of potential applications. Microwaves have been used for the purification of CNTs and for their chemical functionalization, providing a technique for simple, green, and large-scale protocols. In addition, the selective destruction of metallic CNTs under microwave irradiation could potentially result in a batch of semiconducting-only nanotubes. As an innovative application, the combination of microwaves with well-aligned CNTs could produce a new illumination technology. Moreover, the microwave absorbing properties of CNTs and their different behavior from typical organic compounds may open the door to the preparation of a wide range of new materials useful in many fields. A few examples of practical applications include electromagnetic interference for protecting the environment from radiation and microwave hyperthermia for cancer treatment as well as other medical therapies requiring precise heating of biological tissues. PMID:20025299

  17. Unlocking Potentials of Microwaves for Food Safety and Quality

    PubMed Central

    Tang, Juming

    2015-01-01

    Microwave is an effective means to deliver energy to food through polymeric package materials, offering potential for developing short-time in-package sterilization and pasteurization processes. The complex physics related to microwave propagation and microwave heating require special attention to the design of process systems and development of thermal processes in compliance with regulatory requirements for food safety. This article describes the basic microwave properties relevant to heating uniformity and system design, and provides a historical overview on the development of microwave-assisted thermal sterilization (MATS) and pasteurization systems in research laboratories and used in food plants. It presents recent activities on the development of 915 MHz single-mode MATS technology, the procedures leading to regulatory acceptance, and sensory results of the processed products. The article discusses needs for further efforts to bridge remaining knowledge gaps and facilitate transfer of academic research to industrial implementation. PMID:26242920

  18. Unlocking Potentials of Microwaves for Food Safety and Quality.

    PubMed

    Tang, Juming

    2015-08-01

    Microwave is an effective means to deliver energy to food through polymeric package materials, offering potential for developing short-time in-package sterilization and pasteurization processes. The complex physics related to microwave propagation and microwave heating require special attention to the design of process systems and development of thermal processes in compliance with regulatory requirements for food safety. This article describes the basic microwave properties relevant to heating uniformity and system design, and provides a historical overview on the development of microwave-assisted thermal sterilization (MATS) and pasteurization systems in research laboratories and used in food plants. It presents recent activities on the development of 915 MHz single-mode MATS technology, the procedures leading to regulatory acceptance, and sensory results of the processed products. The article discusses needs for further efforts to bridge remaining knowledge gaps and facilitate transfer of academic research to industrial implementation. PMID:26242920

  19. Microwave enhancement of thermal land mine signatures

    NASA Astrophysics Data System (ADS)

    Hermann, John A.; Chant, Ian J.

    1999-08-01

    Buried landmine detection using IR sensor has been investigated by a number of researchers around the world. The technique is promising, particularly for unpaved roads in hot dry countries with little roadside shading. The thermal source for this detection mechanism is the solar heat flux and this imposes constraints on the time of day and weather conditions when this technique is effective. Here we investigate the use of a microwave energy source to drive the thermal flux with the aim of extending the usefulness of IR detection to full day operation in all forms of overcast weather. The microwave radiation penetrates the soil providing a depth to the heating process. We present a 1D model of microwave absorption and heat dissipation by moisture-laden soils which contain landmine-like buried objects. The microwave source for our numerical experiments is a 2.45 GHz, 5 kW. If required, a possible power increase to as high as 50 kW is envisaged. The physical mechanisms employed are suitable for a vehicle mounted detection system. We consider thermal properties of plastic bodied landmines shallowly buried in soil at the peak power point in the ground footprint of the heat source and review some of the factors which govern the thermal difference which will result. In particular we review (a) the factors which determine the radiant power penetrating the ground, and (b) the absorption and conduction processes which subsequently occur within the vicinity of the landmine.

  20. In situ decontamination of spills and landfills by focussed microwave/radio frequency heating and closed-loop vapor flushing and vacuum recovery system

    SciTech Connect

    Johnson, P.C.; Otermat, A.L.; Chou, C.C.

    1991-12-31

    This patent describes a system for the in situ decontamination of a zone of contaminated soil in a spill or landfill. It comprises an injection well located outside the contaminated zone but traversing at least the entire depth of the contaminated zone; perforations in the injection well corresponding only to the thickness of the contaminated zone; means for injecting a vapor into the injection well whereby the vapor is forced through the perforations in the injection well; an extraction well traversing the contaminated zone, the well having perforations only through the thickness of the contaminated zone; means for pulling a vacuum in the extraction well whereby the vapors will be drawn from the injection well, through the contaminated zone and into the extraction well thereby flushing and cleansing contaminants from the contaminated zone; means connected to the outlet of the extraction well for treating the contaminated vapors and recycling the treated vapor to the injection well; and means for heating the surface above the contaminated zone thereby enhancing volatilization of the contaminants in the contaminated zone.

  1. Medical applications of microwaves

    NASA Astrophysics Data System (ADS)

    Vrba, Jan; Lapes, M.

    2004-04-01

    Medical applications of microwaves (i.e. a possibility to use microwave energy and/or microwave technique and technology for therapeutical purposes) are a quite new and a very rapidly developing field. Microwave thermotherapy is being used in medicine for the cancer treatment and treatment of some other diseases since early eighties. In this contribution we would like to offer general overview of present activities in the Czech Republic, i.e. clinical applications and results, technical aspects of thermo therapeutic equipment and last but not least, prospective diagnostics based on microwave principals ant technology and instrumentation.

  2. Microwave synthesis and actuation of shape memory polycaprolactone foams with high speed

    PubMed Central

    Zhang, Fenghua; Zhou, Tianyang; Liu, Yanju; Leng, Jinsong

    2015-01-01

    Microwave technology is a highly effective approach to fast and uniform heating. This article investigates that the microwave heating as a novel method is used to rapidly foam and actuate biocompatible and biodegradable shape memory crosslinked-polycaprolactone (c-PCL) foams. The optical microscope proves that the resulting c-PCL foams have homogenous pore structure. Mechanical behavior and shape memory performance of c-PCL foams are investigated by static materials testing. Shape recovery ratio is approximately 100% and the whole recovery process takes only 98 s when trigged by microwave. Due to the unique principle of microwave heating, the recovery speed of c-PCL foams in microwave oven is several times faster than that in hot water and electric oven. Hence compared to the traditional heating methods, microwave is expected to bring more advantages to modern industry and scientific research in the field of smart materials and structures. PMID:26053586

  3. Microwave synthesis and actuation of shape memory polycaprolactone foams with high speed.

    PubMed

    Zhang, Fenghua; Zhou, Tianyang; Liu, Yanju; Leng, Jinsong

    2015-01-01

    Microwave technology is a highly effective approach to fast and uniform heating. This article investigates that the microwave heating as a novel method is used to rapidly foam and actuate biocompatible and biodegradable shape memory crosslinked-polycaprolactone (c-PCL) foams. The optical microscope proves that the resulting c-PCL foams have homogenous pore structure. Mechanical behavior and shape memory performance of c-PCL foams are investigated by static materials testing. Shape recovery ratio is approximately 100% and the whole recovery process takes only 98 s when trigged by microwave. Due to the unique principle of microwave heating, the recovery speed of c-PCL foams in microwave oven is several times faster than that in hot water and electric oven. Hence compared to the traditional heating methods, microwave is expected to bring more advantages to modern industry and scientific research in the field of smart materials and structures. PMID:26053586

  4. Microwave synthesis and actuation of shape memory polycaprolactone foams with high speed

    NASA Astrophysics Data System (ADS)

    Zhang, Fenghua; Zhou, Tianyang; Liu, Yanju; Leng, Jinsong

    2015-06-01

    Microwave technology is a highly effective approach to fast and uniform heating. This article investigates that the microwave heating as a novel method is used to rapidly foam and actuate biocompatible and biodegradable shape memory crosslinked-polycaprolactone (c-PCL) foams. The optical microscope proves that the resulting c-PCL foams have homogenous pore structure. Mechanical behavior and shape memory performance of c-PCL foams are investigated by static materials testing. Shape recovery ratio is approximately 100% and the whole recovery process takes only 98 s when trigged by microwave. Due to the unique principle of microwave heating, the recovery speed of c-PCL foams in microwave oven is several times faster than that in hot water and electric oven. Hence compared to the traditional heating methods, microwave is expected to bring more advantages to modern industry and scientific research in the field of smart materials and structures.

  5. Microwave sintering of Ce-Y-ZTA composites

    SciTech Connect

    Xi, Z.; Huang, Y.; Zhang, R.; Yang, J.; Wang, S.

    1997-11-01

    Microwave processing of ceramic materials--especially the sintering of Al{sub 2}O{sub 3}, ZrO{sub 2} and their composites--has been investigated during the past decade by many researchers. Electromagnetic waves interact with ceramic materials, leading to volumetric heating by dielectric loss. This enhances the sintering process and decreases sintering active energy and densification temperature. Microwave heating also has the potential for energy and cost savings when compared with conventional heating. Zirconia-toughened alumina (ZTA) has received attention for its rapid densification in a microwave furnace. This article examines the batch microwave sintering of ZTA--30 wt% ceria-yttria-stabilized tetragonal zirconia polycrystals (Ce-Y-TZP) + 70 wt% Al{sub 2}O{sub 3}--including: (1) the microwave process in a multimode cavity with a hybrid heating structure; (2) the flexural strength, fracture toughness and wear resistance of the microwave-sintered materials; (3) the relationship between sintering temperature and microstructure/mechanical properties of the sintered samples; and (4) the comparison between microwave-sintered and conventionally sintered materials.

  6. The microwave-to-flow paradigm: translating high-temperature batch microwave chemistry to scalable continuous-flow processes.

    PubMed

    Glasnov, Toma N; Kappe, C Oliver

    2011-10-17

    The popularity of dedicated microwave reactors in many academic and industrial laboratories has produced a plethora of synthetic protocols that are based on this enabling technology. In the majority of examples, transformations that require several hours when performed using conventional heating under reflux conditions reach completion in a few minutes or even seconds in sealed-vessel, autoclave-type, microwave reactors. However, one severe drawback of microwave chemistry is the difficulty in scaling this technology to a production-scale level. This Concept article demonstrates that this limitation can be overcome by translating batch microwave chemistry to scalable continuous-flow processes. For this purpose, conventionally heated micro- or mesofluidic flow devices fitted with a back-pressure regulator are employed, in which the high temperatures and pressures attainable in a sealed-vessel microwave chemistry batch experiment can be mimicked. PMID:21932289

  7. High brightness microwave lamp

    DOEpatents

    Kirkpatrick, Douglas A.; Dolan, James T.; MacLennan, Donald A.; Turner, Brian P.; Simpson, James E.

    2003-09-09

    An electrodeless microwave discharge lamp includes a source of microwave energy, a microwave cavity, a structure configured to transmit the microwave energy from the source to the microwave cavity, a bulb disposed within the microwave cavity, the bulb including a discharge forming fill which emits light when excited by the microwave energy, and a reflector disposed within the microwave cavity, wherein the reflector defines a reflective cavity which encompasses the bulb within its volume and has an inside surface area which is sufficiently less than an inside surface area of the microwave cavity. A portion of the reflector may define a light emitting aperture which extends from a position closely spaced to the bulb to a light transmissive end of the microwave cavity. Preferably, at least a portion of the reflector is spaced from a wall of the microwave cavity. The lamp may be substantially sealed from environmental contamination. The cavity may include a dielectric material is a sufficient amount to require a reduction in the size of the cavity to support the desired resonant mode.

  8. Microwave hemorrhagic stroke detector

    DOEpatents

    Haddad, Waleed S.; Trebes, James E.

    2007-06-05

    The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stoke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

  9. Microwave hemorrhagic stroke detector

    DOEpatents

    Haddad, Waleed S.; Trebes, James E.

    2002-01-01

    The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stroke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

  10. Apparatus for mounting a diode in a microwave circuit

    DOEpatents

    Liu, Shing-gong

    1976-07-27

    Apparatus for mounting a diode in a microwave circuit for making electrical contact between the circuit and ground and for dissipation of heat between the diode and a heat sink. The diode, supported on a thermally and electrically conductive member, is resiliently pressed in electrical contact with the microwave circuit. A tapered collar on the member is elastically deformably wedged into a tapered aperture formed in a heat sink. The wedged collar tightens firmly around the member establishing good thermal and electrical conduction from the diode to the heat sink and ground. Disassembly is facilitated because of the elastically deformed collar.

  11. Microwave Therapy for Bone Tumors

    NASA Astrophysics Data System (ADS)

    Takakuda, Kazuo; Inaoka, Shuken; Saito, Hirokazu; Hassan, Moinuddin; Koyama, Yoshikazu; Kuroda, Hiroshi; Kanaya, Tomohiro; Kosaka, Toshifumi; Tanaka, Shigeo; Miyairi, Hiroo; Shinomiya, Kenichi

    In vivo microwave treatments for bone tumor are designed, which enable us to conserve the activity and functionality of the matrix of living tissues. This treatment is composed of two steps. In the first step, the tumor was coagulated by the application of microwaves emitted from the antenna inserted into the tumor tissue, and then removed. In the second step, the surrounding tissue suspected to be invaded with transformed cells was covered with hydro gels and heated similarly. The tissue itself was heated by the conduction from the gels. The tissue temperature should be kept at 60°C for 30 minutes. This treatment should kill the whole cells within the tissues, but the mechanical strength and the biochemical activity of the matrix should be left intact. The matrix preserves the mechanical functions and ensures the maximum regeneration ability of the tissue. In this study, various hydro gels were examined and the most promising one was selected. Animal experiments were carried out and successful heating verified the applicability of the treatment.

  12. Combination microwave ovens: an innovative design strategy.

    PubMed

    Tinga, Wayne R; Eke, Ken

    2012-01-01

    Reducing the sensitivity of microwave oven heating and cooking performance to load volume, load placement and load properties has been a long-standing challenge for microwave and microwave-convection oven designers. Conventional design problem and solution methods are reviewed to provide greater insight into the challenge and optimum operation of a microwave oven after which a new strategy is introduced. In this methodology, a special load isolating and energy modulating device called a transducer-exciter is used containing an iris, a launch box, a phase, amplitude and frequency modulator and a coupling plate designed to provide spatially distributed coupling to the oven. This system, when applied to a combined microwave-convection oven, gives astounding performance improvements to all kinds of baked and roasted foods including sensitive items such as cakes and pastries, with the only compromise being a reasonable reduction in the maximum available microwave power. Large and small metal utensils can be used in the oven with minimal or no performance penalty on energy uniformity and cooking results. Cooking times are greatly reduced from those in conventional ovens while maintaining excellent cooking performance. PMID:24432587

  13. Microwave cyclodestruction: evaluation on human eyes.

    PubMed Central

    Finger, P T; Perry, H D; Shakin, J L; Bisciotti, D R; Nattis, R J

    1995-01-01

    AIMS--The study was set up to evaluate the effect of microwave cyclodestruction on human eyes. METHODS--Two human eyes were studied. For treatment a horn shaped 5.8 GHz microwave applicator and fibre optic thermometry were used. Just before enucleation, the rectangular (2 x 3 mm) microwave aperture was placed onto the conjunctiva at a position 1-2 mm posterior to the corneal scleral limbus. Each of three to four treatment spots was targeted to receive a thermal dose of 54 degrees C for 1 minute. Clinical, gross, and histopathological evaluations were performed. RESULTS--Clinical evaluations of the treatment sites (immediately after microwave application) revealed no evidence of conjunctival or scleral damage. Trace fluorescein 2% uptake was noted within the targeted zones. The first eye was sectioned along the equatorial axis. Examination of the ciliary body and pars plana revealed whitening of the ciliary processes and depigmentation. Histopathological evaluations revealed ciliary epithelial necrosis with pigment dispersion. The vascularity of the ciliary processes showed focal disruption and haemorrhage. The underlying ciliary muscle and sclera appeared to be unaffected. No other findings could be attributed to microwave cyclodestruction. CONCLUSION--The results of this phase I toxicity study suggest that microwave heating can be used to damage preferentially the epithelial layers of the human ciliary body. Images PMID:7662635

  14. Fluidized bed heat treating system

    SciTech Connect

    Ripley, Edward B; Pfennigwerth, Glenn L

    2014-05-06

    Systems for heat treating materials are presented. The systems typically involve a fluidized bed that contains granulated heat treating material. In some embodiments a fluid, such as an inert gas, is flowed through the granulated heat treating medium, which homogenizes the temperature of the heat treating medium. In some embodiments the fluid may be heated in a heating vessel and flowed into the process chamber where the fluid is then flowed through the granulated heat treating medium. In some embodiments the heat treating material may be liquid or granulated heat treating material and the heat treating material may be circulated through a heating vessel into a process chamber where the heat treating material contacts the material to be heat treated. Microwave energy may be used to provide the source of heat for heat treating systems.

  15. Novel aspects of microwave processing of ceramic materials

    SciTech Connect

    Willert-Porada, M.

    1995-09-01

    A brief description of microwave sintering with respect to the chemical selectivity of heating by microwaves is given. For low dielectric loss materials, like alumina, selective heating is used to preheat the ceramic in order to increase the dielectric loss. As compared to conventional sintering an increased grain growth and neck growth as well as grain facetting of the Al{sub 2}O{sub 3}-ceramic is found in the early stage of sintering. The microstructure-modeling potential of microwave heating based on the selectivity of microwave-material interaction is further demonstrated for Al{sub 2}O{sub 3}-TiO{sub 2} ceramics and for metal-ceramic gradient materials.

  16. Microwave processing of ceramics and ceramic composites using a single-mode microwave cavity

    NASA Astrophysics Data System (ADS)

    Lee, Ki-Yong

    This research seeks (i) to use a single-mode microwave cavity to process ceramics and ceramic based composites, (ii) to study the conditions or parameters needed to successfully apply the microwaves to processing of materials, and (iii) to study the interactions between materials and microwaves. In sintering studies, alumina ceramics and alumina matrix 10wt% zirconia composites were microwave-heated between 1500sp°C and 1600sp°C giving a density of about 96% up to nearly 100% of theoretical without 'thermal runaway' or cracking. The density, hardness, and toughness for individually- and batch-processed specimens were relatively uniform with respect to the cavity mode and specimens' location inside the insulation called 'casket' during microwave heating. For example, the mean and standard deviation of the hardness was 16.19 GPa ± 0.58 GPa for a total of 24 alumina specimens microwave-heated in batches of 6 specimens each. This corresponds to a coefficient of variation of only 0.036. Microwave power was successfully utilized to burn out organic binder from ceramic powder compacts without cracking the specimens and without using any insulation material to enclose the specimens. The extent of binder burn-out significantly depended on material composition due to the dielectric properties of each material. For example, Alsb2Osb3/10wt% SiC burned out the binder more successfully than either monolithic alumina or alumina containing 10wt% zirconia. In a joining study, ceramic materials and glass ceramics were successfully joined using a spin-on material interlayer under ambient or low externally applied pressures. Notches of submillimeter dimension were made in the specimens prior to joining. During the joining process the notch dimensions changed by no more than a few percent. In addition, this study revealed that compared to conventional heating, microwave heating has remarkable effects in crack healing. For alumina specimens with initial Vickers cracks about 350mum

  17. Further Developments in Microwave Ablation of Prostate Cells

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey; Ngo, Phong

    2005-01-01

    A report presents additional information about the subject matter of Microwave Treatment of Prostate Cancer and Hyperplasia (MSC-23049), NASA Tech Briefs, Vol. 29, No. 6 (June 2005), page 62. To recapitulate: the basic idea is to use microwaves to heat and thereby kill small volumes of unhealthy prostate tissue. The prostate is irradiated with microwaves from one or more antennas positioned near the prostate by means of catheters inserted in the urethra and/or colon. The microwave frequency, power, and exposure time, phasing, positions, and orientations of the antennas may be chosen to obtain the desired temperature rise in the heated region and to ensure that the location and extent of the heated region coincides with the region to be treated to within a few millimeters. Going beyond the description in the cited previous article, the report includes a diagram that illustrates typical placement of urethra and colon antenna catheters and presents results of computationally simulated prostate-heating profiles for several different combinations of antenna arrangements, frequencies, and delivered- energy levels as well as experimental results within phantom materials. The advantage of the two-antenna technology is that the heat generated at each antenna is significantly reduced from that associated with only one antenna. The microwave energy radiated from each antenna is focused at the tumor center by adjusting the phasing of the irradiated microwave signal from the antennas.

  18. Electron-cyclotron-heating experiments in tokamaks and stellarators

    SciTech Connect

    England, A.C.

    1983-01-01

    This paper reviews the application of high-frequency microwave radiation to plasma heating near the electron-cyclotron frequency in tokamaks and stellarators. Successful plasma heating by microwave power has been demonstrated in numerous experiments. Predicted future technological developments and current theoretical understanding suggest that a vigorous program in plasma heating will continue to yield promising results.

  19. Effect of microwave radiation on coal flotation

    SciTech Connect

    Ozbayoglu, G.; Depci, T.; Ataman, N.

    2009-07-01

    Most low-rank coals are high in moisture and acid functional groups, therefore showing poor floatability. Drying, which removes the water molecules trapped in the pores and adsorbed at the surface of coal, decreases the hydrophilic character and improves the floatability. Microwave heating, whose simplest application is drying, was applied at 0.9 kW power level for 60 sec exposure time in the experiments to decrease the moisture content of coal in order to enhance the hydrophobicity. The flotation tests of microwave-treated coal by using heptanol and octanol lead to a higher flotation yield and ash removal than original coal.

  20. Microwave Lightcraft concept

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Looking like an alien space ship or a flying saucer the Microwave Lightcraft is an unconventional launch vehicle approach for delivering payload to orbit using power transmitted via microwaves. Microwaves re beamed from either a ground station or an orbiting solar power satellite to the lightcraft. The energy received breaks air molecules into a plasma and a magnetohydrodynamic fanjet provides the lifting force. Only a small amount of propellant is required for circulation, attitude control and deorbit.

  1. Microwave Radiometric Signatures of Different Surface Types in Deserts

    NASA Technical Reports Server (NTRS)

    Prigent, Catherine; Rossow, William B.; Matthews, Elaine; Marticorena, Beatrice

    1999-01-01

    In arid environments, specific microwave signatures have been observed with the Special Sensor Microwave/Imager (SSM/I). For a given diurnal change in surface skin temperature, the corresponding change in the microwave brightness temperature is smaller than expected. With the help of a 1D, time-dependent heat conduction model, this behavior is explained by microwave radiation coming from different depths in the soil, depending on the soil type and on the microwave radiation frequency. Using the eight-times daily estimates of the surface skin temperature by the International Satellite Cloud Climatology Project (ISCCP) and a simple Fresnel model, collocated month-long time series of the SSM/I brightness temperatures and the surface skin temperatures give a consistent estimate of the effective microwave emissivity and penetration depth parameters. Results are presented and analyzed for the Sahara and the Arabian Peninsula, for July and November 1992. The case of the Australian desert is also briefly mentioned. Assuming a reasonable thermal diffusivity for the soil in desert areas, the microwave radiation is estimated to come from soil layers down to depths of at least five wavelengths in some locations. Regions where the microwave radiation comes from deeper soil layers also have large microwave emissivity polarization differences and large visible reflectances, suggesting that these areas correspond to sand dune fields.

  2. Microwave-induced cracking of pyrolytic tars coupled to microwave pyrolysis for syngas production.

    PubMed

    Beneroso, D; Bermúdez, J M; Montes-Morán, M A; Arenillas, A; Menéndez, J A

    2016-10-01

    Herein a new process is proposed to produce a syngas-rich gas fraction (>80vol% H2+CO) from biowaste based on microwave heating within two differentiated steps in order to avoid tars production. The first step consists of the microwave pyrolysis of biowaste induced by a char-based susceptor at 400-800°C; tars, char and syngas-rich gas fractions being produced. The tars are then fed into the second step where a portion of the char from the first step is used as a bed material in a 0.3:1wt% ratio. This bed is heated up by microwaves up to 800°C, allowing thermal cracking of tars and additional syngas (>90vol% H2+CO) being then produced. This new concept arises as an alternative technology to the gasification of biowastes for producing syngas with no need for catalysts or gasifying reagents to minimise tars production. PMID:27420155

  3. Microwave assisted pultrusion of an epoxy composite

    SciTech Connect

    Methven, J.M.; Abidin, A.Z.

    1995-12-01

    A 6mm diameter cylindrical profile based on E-glass fibers and a BF{sub 3}-triamine-epoxy resin system has been manufactured by Microwave Assisted Pultrusion (MAP) using a single mode resonant microwave cavity operating in a TM{sub 010} mode at 2450 MHz. Power transfer is at least 70% and pulling speeds of more than 2m/minute have been achieved for a power input of about 800W. The results are consistent with earlier MAP studies using unsaturated polyesters, epoxies urethane acrylates and vinyl esters. The results provide a sound basis for proposing the use of this type of epoxy system as a material that is suitable for a high speed gel-cure pultrusion process that uses both a microwave heating cavity and a conventional pultrusion die.

  4. Microwave accelerator E-beam pumped laser

    DOEpatents

    Brau, Charles A.; Stein, William E.; Rockwood, Stephen D.

    1980-01-01

    A device and method for pumping gaseous lasers by means of a microwave accelerator. The microwave accelerator produces a relativistic electron beam which is applied along the longitudinal axis of the laser through an electron beam window. The incident points of the electron beam on the electron beam window are varied by deflection coils to enhance the cooling characteristics of the foil. A thyratron is used to reliably modulate the microwave accelerator to produce electron beam pulses which excite the laser medium to produce laser pulse repetition frequencies not previously obtainable. An aerodynamic window is also disclosed which eliminates foil heating problems, as well as a magnetic bottle for reducing laser cavity length and pressures while maintaining efficient energy deposition.

  5. Microwave Assisted Wolff-Kishner Reduction Reaction

    NASA Astrophysics Data System (ADS)

    Parquet, Eric; Lin, Qun

    1997-10-01

    A Wolff-Kishner reduction of a carbonyl group was carried out in a household microwave oven. Isatin was first converted to the hydrazone with 55% hydrazine and ethylene glycol by irradiation in the microwave oven at medium power for 30 seconds. Then, isatin 3-hydrazone was mixed with ethylene glycol and potassium hydroxide and irradiated in the microwave oven for only 10 seconds. After simple work-up and recrystallization, oxindole was obtained in a yield of 32.4%. The two step syntheses described here offer several advantages: (1) very short reaction time with no need for special microscale glassware, (2) mild experimental conditions (hot oil baths and heating mantles are not required), (3) the reagents are easy to handle (students do not need to prepare sodium ethoxide from sodium metal and absolute ethanol).

  6. Ionosphere/microwave beam interaction study

    NASA Technical Reports Server (NTRS)

    Gordon, W. E.; Duncan, L. M.

    1978-01-01

    The microwave beam of the Solar Power Satellite (SPS) is predicted to interact with the ionosphere producing thermal runaway up to an altitude of about 100 kilometers at a power density threshold of 12 mW/cm sq (within a factor of two). The operation of the SPS at two frequencies, 2450 and 5800 MHz, is compared. The ionosphere interaction is less at the higher frequency, but the tropospheric problem scattering from heavy rain and hail is worse at the higher frequency. Microwave signals from communication satellites were observed to scintillate, but there is some concern that the uplink pilot signal may be distorted by the SPS heated ionosphere. The microwave scintillations are only observed in the tropics in the early evenings near the equinoxes. Results indicate that large phase errors in the uplink pilot signal can be reduced.

  7. Salmonella outbreak from microwave cooked food.

    PubMed Central

    Evans, M. R.; Parry, S. M.; Ribeiro, C. D.

    1995-01-01

    Following a buffet meal served to six guests at a private domestic function, five of the guests and the host developed symptoms of food poisoning. Salmonella enteritidis phage type 4 (PT4) was isolated from all four individuals who submitted faecal samples for investigation. Leftover samples of a savoury rice dish consumed by all six ill persons contained 6 x 10(3)/gm Salmonella enteritidis PT4. The rice salad comprised boiled rice, raw carrots, eggs, cheese and curry powder. The curry powder and remainder of the pack of six eggs were negative on microbiological analysis. The rice dish had been prepared by heating in a 500 W microwave oven with a rotating turntable on full power for 5 min. Although the hazards of inadequate microwave cooking are well recognized, this is only the second outbreak of food poisoning from microwave cooking to be reported. PMID:7589262

  8. PROGRESS TOWARDS MICROWAVE IGNITION OF EXPLOSIVES

    SciTech Connect

    Curling, Mark; Collins, Adam; Dima, Gabriel; Proud, William

    2009-12-28

    It is known that various materials are caused to spark when subjected to microwave radiation, and others can be heated to extremely high temperatures. This paper studies the behaviour of graphite under microwave radiation using a multi-mode 2.45 GHz+-50 Hz microwave cavity, and its potential applications in propellant ignition systems. Evidence for a correlation between sample mass and arcing intensity is presented, and a linear relationship between sample mass and temperature is found. Both graphite powder and flakes show increasing arcing intensity with increasing mass up to approx150 mg, after which the behaviour is more dispersed. The temperature achieved increases linearly with increasing mass, with maximum temperatures of 1,011 deg. C and 657 deg. C achieved for powder (<0.1 mm) and flakes respectively--well above thermal ignition temperatures for most common explosives.

  9. Microwave Sintering of Silver Nanoink for Radio Frequency Applications.

    PubMed

    Kim, Kwang-Seok; Park, Bum-Geun; Jung, Kwang-Ho; Kim, Jong-Woong; Jeong, Myung Yung; Jung, Seung-Boo

    2015-03-01

    Microwave sintering is a promising method for low-temperature processes, as it provides advantages such as uniform, fast, and volumetric heating. In this study, we investigated the electrical characteristics of inkjet-printed silver (Ag) circuits sintered by microwaves. The microstructural evolutions of inkjet-printed Ag circuits sintered at various temperatures for different durations were observed with a field emission scanning electron microscope. The electrical properties of the inkjet-printed Ag circuits were analysed by electrical resistivity measurements and radio frequency properties including scattering-parameters in the frequency range of 20 MHz to 20 GHz. The experimental results show that the signal losses of the Ag circuits sintered by microwave heating were lower than those sintered by conventional heating as microwave heating led to granular films which were nearly fully sintered without pores on the surfaces. When the inkjet-printed Ag circuits were sintered by microwaves at 300 °C for 4 min, their electrical resistivity was 5.1 µΩ cm, which is 3.2 times larger than that of bulk Ag. Furthermore, microwave sintering at 150 °C for 4 min achieved much lower signal losses (1.1 dB at 20 GHz) than conventional sintering under the same conditions. PMID:26413662

  10. Uniform bulk Material Processing using Multimode Microwave Radiation

    SciTech Connect

    Varma, Ravi; Vaughan, Worth E.

    1999-06-18

    An apparatus for generating uniform heating in material contained in a cylindrical vessel is described. TE{sub 10}-mode microwave radiation is coupled into a cylindrical microwave transition such that microwave radiation having TE{sub 11}-, TE{sub 01}- and TM{sub 01}-cylindrical modes is excited therein. By adjusting the intensities of these modes, substantially uniform heating of materials contained in a cylindrical drum which is coupled to the microwave transition through a rotatable choke can be achieved. The use of a poor microwave absorbing insulating cylindrical insert, such as aluminum oxide, for separating the material in the container from the container walls and for providing a volume through which air is circulated is expected to maintain the container walls at room temperature. The use of layer of highly microwave absorbing material, such as SiC, inside of the insulating insert and facing the material to be heated is calculated to improve the heating pattern of the present apparatus.

  11. Method and device for microwave sintering large ceramic articles

    DOEpatents

    Kimrey, Jr., Harold D.

    1990-01-01

    A microwave sintering system and method are provided for extremely uniform sintering of large and/or irregular shaped ceramic articles at microwave frequencies of at least 28 GHz in the hundreds of kilowatts power range in an untuned cavity. A 28 GHz, 200 kw gyrotron with variable power output is used as the microwave source connected to an untuned microwave cavity formed of an electrically conductive housing through an overmoded waveguide arrangement which acts in conjunction with a mode promoter within the cavity to achieve unexpected field uniformity. The part to be sintered is placed in the cavity and supported on a removable high temperature table in a central location within the cavity. The part is surrounded by a microwave transparent bulk insulating material to reduce thermal heat loss at the part surfaces and maintain more uniform temperature. The cavity may be operated at a high vacuum to aid in preventing arcing. The system allows controlled increased heating rates of greater than 200.degree. C./min to provide rapid heating of a ceramic part to a selected sintering temperature where it is maintained by regulating the microwave power applied to the part. As a result of rapid heating, the extent of non-isothermal processes such as segregation of impurities to the grain boundaries are minimized and exaggerated grain growth is reduced, thereby strengthening the mechanical properties of the ceramic part being sintered.

  12. A device for microwave sintering large ceramic articles

    DOEpatents

    Kimrey, H.D. Jr.

    1987-07-24

    A microwave sintering system is provided for uniform sintering of large and/or irregular shapes ceramic articles at microwave frequencies of at least 28 GHz in the hundreds of kilowatts power range in an untuned cavity. A 28 GHz, 200 kw gyrotron with variable power output is used as the microwave source connected to an untuned microwave cavity formed of an electrically conductive housing. The part to be sintered is placed in the cavity and supported on a removable high temperature table in a central location within the cavity. The part is surrounded by a microwave transparent bulk insulating material to reduce thermal heat loss at the part surfaces and maintain more uniform temperature. The cavity may be operated at a high vacuum to aid in preventing arcing. The system allows controlled increased heating rates of greater than 200/degree/C/min to provide rapid heating of a ceramic part to a selected sintering temperature where it is maintained by regulating the microwave power applied to the part. As a result of rapid heating, the extent on non-isothermal processes such as segregation of impurities to the grain boundaries are minimized and exaggerated grain growth is reduced, thereby strengthening the mechanical properties of the ceramic part being sintered. 1 fig.

  13. Uniform bulk material processing using multimode microwave radiation

    DOEpatents

    Varma, Ravi; Vaughn, Worth E.

    2000-01-01

    An apparatus for generating uniform heating in material contained in a cylindrical vessel is described. TE.sub.10 -mode microwave radiation is coupled into a cylindrical microwave transition such that microwave radiation having TE.sub.11 -, TE.sub.01 - and TM.sub.01 -cylindrical modes is excited therein. By adjusting the intensities of these modes, substantially uniform heating of materials contained in a cylindrical drum which is coupled to the microwave transition through a rotatable choke can be achieved. The use of a poor microwave absorbing insulating cylindrical insert, such as aluminum oxide, for separating the material in the container from the container walls and for providing a volume through which air is circulated is expected to maintain the container walls at room temperature. The use of layer of highly microwave absorbing material, such as SiC, inside of the insulating insert and facing the material to be heated is calculated to improve the heating pattern of the present apparatus.

  14. Microwave sintering of Yb:YAG transparent laser ceramics

    NASA Astrophysics Data System (ADS)

    Esposito, Laura; Piancastelli, Andreana; Bykov, Yury; Egorov, Sergei; Eremeev, Anatolii

    2013-02-01

    Reactive sintering of YAG based ceramics is generally performed under high vacuum in graphite-free furnaces in order to guarantee the elimination of pores and absence of any contamination. An alternative densification technique is the field assisted process such as spark plasma sintering and microwave sintering. Both of these methods are characterized by very fast heating rates, low sintering temperatures and short sintering times. The microwave sintering process is different from electric resistance heating since heat is generated in the bulk of the powder compact through electromagnetic radiation absorption and creates within its body uniform temperature distribution. Microwave sintering of laser ceramics is advantageously distinguished by the absence of any elements having high temperature such as electric heaters or dies which materials can contaminate the sintered parts. In addition, the inverse temperature distribution that exists within the body under volumetric microwave heating is favorable for elimination of porosity. Microwave sintering of Yb:YAG samples were tested and the obtained results are presented. The samples were sintered on a gyrotron-based system operating at a frequency of 24 GHz with microwave power up to 6 kW. Reactive sintering of YAG doped with 1.0, 5.0, and 9.8 at.% Yb2O3 was performed in different temperature-time regimes. The microstructure and the optical transmittance of the obtained samples were compared to those of samples obtained by conventional high vacuum sintering.

  15. Technical aspects of microwave thermotherapy.

    PubMed

    Vrba, J; Lapes, M; Oppl, L

    1999-05-01

    We describe our new technical results dealing with microwave thermotherapy (hyperthermia) in cancer treatment, see Refs. [S.B. Field, C. Franconi (Eds.), Physics and technology of hyperthermia, NATO Seminar Proceedings, Urbino, Italy, 1986; J. Hand, J.R. James (Eds.), Physical Techniques in Clinical Hyperthermia, Wiley, New York, 1986; J. Vrba, M. Lapes, Microwave Applicators for Medical Purposes, CTU Press, 1996, in Czech; J. Vrba, C. Franconi, M. Lapes, Theoretical limits for the penetration depth of the intracavitary applicators, International Journal of Hyperthermia, 12:6 (1996) 737-742; C. Franconi, J. Vrba, F. Montecchia, 27 MHz hybrid evanescent-mode applicators with flexible heating field for deep and safe subcutaneous hyperthermia, International Journal of Hyperthermia, 9:5 (1993) 655-674.]. Our research interest is to develop applicators for deep local heating and for intracavitary cancer and/or prostate treatment as well. Further, a system for 3D SAR distribution measurements in water phantom is explained. Basic evaluation of clinical results is given. PMID:10379544

  16. Microwave assisted combustion synthesis of non-equilibrium intermetallic compounds.

    PubMed

    Veronesi, Paolo; Rosa, Roberto; Colombini, Elena; Leonelli, Cristina; Poli, Giorgio; Casagrande, Angelo

    2010-01-01

    A simplified model of the microwave-assisted combustion synthesis of Ni and Al metal powders to form the NiAl intermetallic on titanium and steel substrates is presented. The simulation couples an electro-thermal model with a chemical model, accounting for local heat generation due to the highly exothermic nature of the reactions between the powders. Numerical results, validated by experimental values, show that the capability of microwaves to convey energy, and not heat, can be used to alter the temperature profiles during and after the combustion synthesis, leading to unique intermetallic microstructures. This phenomenon is ascribed to the extended existence of high temperature liquid intermetallic phases, which react with the metallic substrates at the interface. Moreover, microwave heating selectivity allows to maintain the bulk of the substrate metallic materials to a much lower temperature, compared to combustion synthesis in conventionally heated furnaces, thus reducing possible unwanted transformations like phase change or oxidation. PMID:21721328

  17. Preparation of magnetic indole-3-acetic acid imprinted polymer beads with 4-vinylpyridine and β-cyclodextrin as binary monomer via microwave heating initiated polymerization and their application to trace analysis of auxins in plant tissues.

    PubMed

    Zhang, Yi; Li, Yuanwen; Hu, Yuling; Li, Gongke; Chen, Yueqin

    2010-11-19

    Auxin is a crucial phytohormone for precise control of growth and development of plants. Due to its low concentration in plant tissues which are rich in interfering substances, the accurate determination of auxins remains a challenge. In this paper, a new strategy for isolation and enrichment of auxins from plant tissues was obtained by the magnetic molecularly imprinted polymer (mag-MIP) beads, which were prepared by microwave heating initiated suspension polymerization using indole-3-acetic acid (IAA) as template. In order to obtain higher selective recognition cavities, an enhanced imprinting method based on binary functional monomers, 4-vinylpyridine (4-VP) and β-cyclodextrin (β-CD), was adopted for IAA imprinting. The morphological and magnetic characteristics of the mag-MIP beads were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy and vibrating sample magnetometry. A majority of resultant beads were within the size range of 80-150μm. Porous surface morphology and good magnetic property were observed. Furthermore, the mag-MIP beads fabricated with 4-VP and β-CD as binary functional monomers exhibited improved recognition ability to IAA, as compared with the mag-MIP beads prepared with the individual monomer separately. Competitive rebinding experiment results revealed that the mag-MIP beads exhibited a higher specific recognition for the template than the non-imprinted polymer (mag-NIP) beads. An extraction method by mag-MIP beads coupled with high performance liquid chromatography (HPLC) was developed for determination of IAA and indole-3-butyric acid (IBA) in plant tissues. Linear ranges for IAA and IBA were in the range of 7.00-100.0μgL(-1) and 10.0-100.0μgL(-1), and the detection limits were 3.9 and 7.4μgL(-1), respectively. The analytical performance was also estimated by seedlings or immature embryos samples from three different plant tissues, pea, rice and wheat. Recoveries were in the range of 70

  18. Phase 2 microwave concrete decontamination results

    SciTech Connect

    White, T.L.; Foster, D. Jr.; Wilson, C.T.; Schaich, C.R.

    1995-04-01

    The authors report on the results of the second phase of a four-phase program at Oak Ridge National Laboratory to develop a system to decontaminate concrete using microwave energy. The microwave energy is directed at the concrete surface through the use of an optimized wave guide antenna, or applicator, and this energy rapidly heats the free water present in the interstitial spaces of the concrete matrix. The resulting steam pressure causes the surface to burst in much the same way popcorn pops in a home microwave oven. Each steam explosion removes several square centimeters of concrete surface that are collected by a highly integrated wave guide and vacuum system. The authors call this process the microwave concrete decontamination, or MCD, process. In the first phase of the program the principle of microwaves concrete removal concrete surfaces was demonstrated. In these experiments, concrete slabs were placed on a translator and moved beneath a stationary microwave system. The second phase demonstrated the ability to mobilize the technology to remove the surfaces from concrete floors. Area and volume concrete removal rates of 10.4 cm{sup 2}/s and 4.9 cm{sup 3}/S, respectively, at 18 GHz were demonstrated. These rates are more than double those obtained in Phase 1 of the program. Deeper contamination can be removed by using a longer residence time under the applicator to create multiple explosions in the same area or by taking multiple passes over previously removed areas. Both techniques have been successfully demonstrated. Small test sections of painted and oil-soaked concrete have also been removed in a single pass. Concrete with embedded metal anchors on the surface has also been removed, although with some increased variability of removal depth. Microwave leakage should not pose any operational hazard to personnel, since the observed leakage was much less than the regulatory standard.

  19. Microwave energy for post-calcination treatment of high-level nuclear wastes

    SciTech Connect

    Gombert, D.; Priebe, S.J.; Berreth, J.R.

    1980-01-01

    High-level radioactive wastes generated from nuclear fuel reprocessing require treatment for effective long-term storage. Heating by microwave energy is explored in processing of two possible waste forms: (1) drying of a pelleted form of calcined waste; and (2) vitrification of calcined waste. It is shown that residence times for these processes can be greatly reduced when using microwave energy rather than conventional heating sources, without affecting product properties. Compounds in the waste and in the glass frit additives couple very well with the 2.45 GHz microwave field so that no special microwave absorbers are necessary.

  20. MICROWAVES IN ORGANIC SYNTHESIS

    EPA Science Inventory

    The effect of microwaves, a non-ionizing radiation, on organic reactions is described both in polar solvents and under solvent-free conditions. The special applications are highlighted in the context of solventless organic synthesis which involve microwave (MW) exposure of neat r...

  1. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1993-01-01

    Recent work in the areas of microwave processing and joining of ceramics is briefly reviewed. Advantages and disadvantages of microwave processing as well as some of the current issues in the field are discussed. Current state and potential for future commercialization of this technology is also addressed.

  2. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1993-04-01

    Recent work in the areas of microwave processing and joining of ceramics is briefly reviewed. Advantages and disadvantages of microwave processing as well as some of the current issues in the field are discussed. Current state and potential for future commercialization of this technology is also addressed.

  3. Television Microwave--1971.

    ERIC Educational Resources Information Center

    Peterson, Roger E.

    Since it became a reality just before World War II, terrestrial microwave has improved in systems and equipments, but with the improvements have come higher costs. Television microwave costs are so high because users are demanding more capability, land prices have increased, operating costs are higher, and there is frequency congestion along many…

  4. Effects of Microwave Radiation on Oil Recovery

    NASA Astrophysics Data System (ADS)

    Esmaeili, Abdollah

    2011-12-01

    A variety of oil recovery methods have been developed and applied to mature and depleted reservoirs in order to improve the efficiency. Microwave radiation oil recovery method is a relatively new method and has been of great interest in the recent years. Crude oil is typically co-mingled with suspended solids and water. To increase oil recovery, it is necessary to remove these components. The separation of oil from water and solids using gravitational settling methods is typically incomplete. Oil-in-water and oil-water-solid emulsions can be demulsified and separated into their individual layers by microwave radiation. The data also show that microwave separation is faster than gravity separation and can be faster than conventional heating at many conditions. After separation of emulsion into water and oil layers, water can be discharged and oil is collected. High-frequency microwave recycling process can recover oil and gases from oil shale, residual oil, drill cuttings, tar sands oil, contaminated dredge/sediments, tires and plastics with significantly greater yields and lower costs than are available utilizing existing known technologies. This process is environmentally friendly, fuel-generating recycler to reduce waste, cut emissions, and save energy. This paper presents a critical review of Microwave radiation method for oil recovery.

  5. Comparative effect of microwaves and boiling on the denaturation of DNA

    SciTech Connect

    Stroop, W.G.; Schaefer, D.C. )

    1989-11-01

    The effect of heat and microwave denaturation of small volumes of double-stranded plasmid DNA has been compared. Samples of intact plasmid DNA had plasmid DNA linearized by digestion with EcoRI were conventionally denatured in a boiling water bath or denatured by 2450 MHz of microwave energy for 0-300 s. Heat denaturation for periods longer than 120 s caused breakdown of linearized plasmid DNA; however, microwave denaturation for 10-300 s caused no apparent degradation of linearized DNA. Breakdown of DNA forms II and III was noted in plasmid DNA subjected to 300 s of either heat or microwave denaturation but breakdown of forms II and III occurred more quickly with heat than with microwave treatment. Microwave treatment was also found to be better than heat to denature 32P-labeled DNA probes subsequently used to detect homologous DNA samples immobilized on nitrocellulose filters. A microwave-treated 32P-labeled DNA probe was able to hybridize to DNA samples 20 times more dilute than a heat-treated 32P-labeled DNA probe. Depending on the form of DNA to be analyzed, these results indicate that small volumes of DNA solutions and radiolabeled DNA probes can be effectively denatured in a conventional microwave oven.

  6. Microwave-assisted methanolysis of green coffee oil.

    PubMed

    Oigman, S S; de Souza, R O M A; Dos Santos Júnior, H M; Hovell, A M C; Hamerski, L; Rezende, C M

    2012-09-15

    Optimisation of a microwave-assisted methanolysis was performed to obtain cafestol and kahweol directly from green coffee oil (Coffea arabica). A two-factor (the methanolysis period and temperature), three-level, factorial experimental design (3(2)) was adopted. The methanolysis procedure was performed under microwave irradiation, using closed vessel and accurate fast responding internal fibre-optic temperature probe. The effects on the responses were measured by HPLC. After 3 min of microwave irradiation (hold time) at 100°C, with 500 mg of green coffee oil, a yield higher than 99% was obtained. The yield of this reaction is 26% after 2h when working under conventional heating. The methods described in the literature lead to long reaction times, poor yields and formation of side products. The microwave-assisted technique proved to be faster, avoided undesired side products and gave better conversion, when compared to conventional heating process. PMID:23107719

  7. Contrast-enhanced microwave detection and treatment of breast cancer

    NASA Astrophysics Data System (ADS)

    Gao, Fuqiang

    Contrast agents and heating agents have been proposed for microwave breast tumor imaging and treatment, respectively. The dielectric properties of the tumor are altered with contrast agents or heating agents that locally accumulate in the tumor. The resulting change in dielectric properties of the tumor has the potential to enhance the sensitivity of microwave imaging of breast tumors and increase the efficiency and selectivity of microwave thermal therapy of breast tumors. This dissertation addresses several key challenges in contrast-enhanced microwave imaging and treatment of breast tumors. Carbon nanotubes (CNTs) have been shown to enhance both the relative permittivity and effective conductivity of the host medium, and are promising as theranostic (integrated therapeutic and diagnostic) agents. Thus, our properties characterization work focuses on CNT dispersions. We performed in vitro microwave dielectric properties and heating response characterization of dispersions of CNTs treated by different functionalization methods and identified a CNT formulation that is very promising as a microwave theranostic agent. Stable dispersions of CNTs with concentrations up to 20 mg/ml are obtained with this formulation, and the enhanced microwave properties of these dispersions are extraordinary compared to the control. We also conducted in vivo dielectric properties characterization of mouse tumors with intra-tumoral injections of CNT dispersions and confirmed that the presence of CNTs increases the dielectric properties of the tumor. In parallel, we developed a contrast-enhanced microwave breast tumor imaging algorithm using sparse reconstruction methods. We demonstrated that this algorithm accurately localizes small tumors in 3D numerical breast phantoms. We also demonstrated the experimental feasibility of this method using physical breast phantoms. Lastly, we studied the sensitivity of the distorted Born iterative method (DBIM) to initial guesses and developed a

  8. Microwave hydrology: A trilogy

    NASA Technical Reports Server (NTRS)

    Stacey, J. M.; Johnston, E. J.; Girard, M. A.; Regusters, H. A.

    1985-01-01

    Microwave hydrology, as the term in construed in this trilogy, deals with the investigation of important hydrological features on the Earth's surface as they are remotely, and passively, sensed by orbiting microwave receivers. Microwave wavelengths penetrate clouds, foliage, ground cover, and soil, in varying degrees, and reveal the occurrence of standing liquid water on and beneath the surface. The manifestation of liquid water appearing on or near the surface is reported by a microwave receiver as a signal with a low flux level, or, equivalently, a cold temperature. Actually, the surface of the liquid water reflects the low flux level from the cosmic background into the input terminals of the receiver. This trilogy describes and shows by microwave flux images: the hydrological features that sustain Lake Baykal as an extraordinary freshwater resource; manifestations of subsurface water in Iran; and the major water features of the Congo Basin, a rain forest.

  9. Microwave-assisted regeneration of activated carbon.

    PubMed

    Foo, K Y; Hameed, B H

    2012-09-01

    Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons. PMID:22728787

  10. Microwave plaque thermoradiotherapy for choroidal melanoma.

    PubMed Central

    Finger, P. T.

    1992-01-01

    Microwave thermoradiotherapy was used as a primary treatment for 44 patients with choroidal melanoma. An episcleral dish-shaped microwave antenna was placed beneath the tumour at the time of plaque brachytherapy. While temperatures were measured at the sclera, the tumour's apex was targeted to receive a minimum of 42 degrees C for 45 minutes. In addition, the patients received full or reduced doses of plaque radiotherapy. No patients have been lost to follow-up. Two eyes have been enucleated: one for rubeotic glaucoma, and one for uveitic glaucoma. Though six patients have died, only one death was due to metastatic choroidal melanoma (39 months after treatment). Clinical observations suggest that the addition of microwave heating to plaque radiation therapy of choroidal melanoma has been well tolerated. There has been a 97.7% local control rate (with a mean follow-up of 22.2 months). We have reduced the minimum tumour radiation dose (apex dose) to levels used for thermoradiotherapy of cutaneous melanomas (50 Gy/5000 rad). Within the range of this follow-up period no adverse effects which might preclude the use of this microwave heat delivery system for treatment of choroidal melanoma have been noted. Images PMID:1622949

  11. Microwave radiation hazards around large microwave antenna.

    NASA Technical Reports Server (NTRS)

    Klascius, A.

    1973-01-01

    The microwave radiation hazards associated with the use of large antennas become increasingly more dangerous to personnel as the transmitters go to ever higher powers. The near-field area is of the greatest concern. It has spill over from subreflector and reflections from nearby objects. Centimeter waves meeting in phase will reinforce each other and create hot spots of microwave energy. This has been measured in front of and around several 26-meter antennas. Hot spots have been found and are going to be the determining factor in delineating safe areas for personnel to work. Better techniques and instruments to measure these fields are needed for the evaluation of hazard areas.

  12. Coupled simulation of an electromagnetic heating process using the finite difference time domain method.

    PubMed

    Chen, Hao; Tang, Juming; Liu, Fang

    2007-01-01

    Due to the complexity of interactions between microwaves and food products, a reliable and efficient simulation model can be a very useful tool to guide the design of microwave heating systems and processes. This research developed a model to simulate coupled phenomena of electromagnetic heating and conventional heat transfer by combining commercial electromagnetic software with a customer built heat transfer model. Simulation results were presented and compared with experimental results for hot water and microwave heating in a single mode microwave system at 915 MHz. Good agreement was achieved, showing that this model was able to provide insight into industrial electromagnetic heating processes. PMID:18351003

  13. Rapid microwave annealing for perpendicular oriented cylinders in PS- b-PMMA thin films

    NASA Astrophysics Data System (ADS)

    Qiang, Zhe; Cavicchi, Kevin; Vogt, Bryan; University of Akron Team

    Self-assembly of block copolymer (BCP) has been extensively studied for decades due to their wide range of potential applications such as lithography. Direct microwave annealing provides rapid ordering kinetics. However, the knowledge regarding the structural and orientation evolution of morphology during microwave annealing without solvents remains sparse. Herein, we report on how microwave-annealing conditions impact the morphology developed in cylinder forming PS-b-PMMA films on unmodified silicon wafers. The fraction of perpendicular cylinders developed during microwave annealing is primarily determined by temperature ramp from microwave heating itself. The heating of the substrate during microwave annealing is varied from 0.5 °C/s to 2.8 °C/s by two factors: (1) the microwave output energy and (2) the local heating position of BCP film in the microwave reaction vessel. A maximum in the fraction of perpendicular cylinders (97 %) occurs at 1.83 °C/s and appears independent of the microwave power used. This work demonstrates the importance of controlling conditions of microwave annealing in the morphology developed.

  14. Solar power satellite microwave power transmission system description executive summary

    NASA Astrophysics Data System (ADS)

    Woodcock, G. R.

    1980-12-01

    The history of the concept of microwave power beaming to Earth is reviewed with emphasis on transmission frequency selection. Constraints on the system power level results from (1) required rejection of waste heat resulting from inefficiencies in the cover conversion of dc electric power to microwave power; (2) the rf power intensity in the ionosphere; and (3) the effect of sidelobe level on aperture illumination factors. Transmitter arrangement, the power distribution system, attitude control, subarrays, waveguides, and alignment are discussed.

  15. Using Microwaves for Extracting Water from the Moon

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaukler, William; Hepburn, Frank

    2009-01-01

    This disk contains a video that accompanies the talk. Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles. The video shows the partial results of the COMSOL

  16. Using Microwaves for Extracting Water from the Moon

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.

    2009-01-01

    Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles.

  17. Using Microwaves for Extracting Water from the Moon

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaukler, William; Hepburn, Frank

    2009-01-01

    This disk contains 2 videos that accompanies the talk. Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles. The 1st video shows the results of the COMSOL

  18. Microwave mode shifting antenna system for regenerating particulate filters

    DOEpatents

    Gonze, Eugene V [Pinckney, MI; Kirby, Kevin W [Calabasas Hills, CA; Phelps, Amanda [Malibu, CA; Gregoire, Daniel J [Thousand Oaks, CA

    2011-04-26

    A regeneration system comprises a particulate matter (PM) filter including a microwave energy absorbing surface, and an antenna system comprising N antennas and an antenna driver module that sequentially drives the antenna system in a plurality of transverse modes of the antenna system to heat selected portions of the microwave absorbing surface to regenerate the PM filter, where N is an integer greater than one. The transverse modes may include transverse electric (TE) and/or transverse magnetic (TM) modes.

  19. Joint microwave and infrared studies for soil moisture determination

    NASA Technical Reports Server (NTRS)

    Njoku, E. G.; Schieldge, J. P.; Kahle, A. B. (Principal Investigator)

    1980-01-01

    The feasibility of using a combined microwave-thermal infrared system to determine soil moisture content is addressed. Of particular concern are bare soils. The theoretical basis for microwave emission from soils and the transport of heat and moisture in soils is presented. Also, a description is given of the results of two field experiments held during vernal months in the San Joaquin Valley of California.

  20. Changes in optical behaviour of iron pyritohedron upon microwave treatment

    NASA Astrophysics Data System (ADS)

    Arvind, Hemant K.; Choudhary, B. L.; Dolia, S. N.; Dalela, S.; Jakhar, S. R.; Kumar, Sudhish

    2016-05-01

    We have utilized the volumetric heating of materials by microwave energy absorption for investigating the changes in the optical behavior of a well characterized natural crystal of iron pyritohedron (FeS2). For microwave treatment virgin central core pieces of the FeS2 crystal were ground to fine powder and then heated in a microwave oven for half an hour. Powder XRD measurements confirmed that the microwave treatment on FeS2 does not affect the face centered cubic structure of FeS2. The UV-Visible optical spectrum of the microwave treated FeS2 display a narrow optical absorption peak at ˜315 nm, on the other hand in the UV-Vis spectrum of pure FeS2 a broad absorption band with a maximum centered ˜310-330 nm was observed. The band gap energies for pure and microwave treated FeS2 are estimated to be 1.09 eV and 1.35 eV respectively. This study clearly indicates that microwave treatment results in a blue shift in the absorption edge and enhancement in the band gap energy.