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  • 1
    Electronic Resource
    Electronic Resource
    Melting of silicon surfaces by high-power pulsed microwave radiation (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3243-3253 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the microwave-induced melting and damage to the near-surface region of arsenic-implanted silicon for 1–2 μs pulses at a frequency of 2.856 GHz and an incident pulse power of up to 9 MW. Rectangular samples were irradiated by single-pass TE10 traveling wave pulses inside a WR-284 waveguide, and time-resolved in situ and post-irradiation studies were performed to characterize the material modifications induced by the microwave pulses. The test chamber where the specimens were irradiated was either evacuated to a pressure of 10−7–10−6 Torr or filled with a 30-psig pressure of Freon-12. Incident, transmitted, and reflected powers were monitored with directional couplers and fast diodes. The results of the time-resolved optical measurements for samples irradiated in vacuum show that melting of the near-surface region occurs for pulse powers exceeding 3 MW, and that the surface melting is accompanied by a large increase in the reflected microwave power. The onset of the enhanced reflectivity is measured at an earlier time as the microwave power is increased, and once the abrupt increase in the reflectivity is observed, it persists throughout the remainder of the pulse. Simultaneous with the onset of surface damage, we observe a large enhancement in the emission of light from the sample. Results are presented for the temporal behavior and spectral components of the fluorescence as a function of the incident microwave power. The gas pressure in the test cell was also monitored, and a large increase in the gas pressure was detected at the same pulse power as the threshold for the sudden increase in the microwave reflectivity. The large increments in the reflected microwave power, light emission, and gas pressure are attributed to the formation of a plasma due to gas breakdown at (or near) the sample surface.Examination of the irradiated specimens shows that the melting and damage are not homogeneous over the surface, and the degree of energy deposition from the microwave pulses depends on the ambient gas in the test cell. Using secondary ion mass spectrometry, we find that microwave pulses at a power of 8 MW cause melting and vaporization of the near-surface region up to depths that exceed 1 μm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341543
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  • 2
    Electronic Resource
    Electronic Resource
    Prepulse suppression in microwave pulse-compression cavities (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2475-2480 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It is possible to generate high-power microwave pulses with fast rise time by using resonant cavities to obtain power gain from pulse compression. In the usual case, especially when normal-conducting cavities are used, the principal output pulse from a pulse-compression device is preceded by a precursor signal that may be only 40 dB below the main pulse. For some applications this large a prepulse is unacceptable. We have developed a prototype normal-conducting, x-band, pulse-compression cavity in which the prepulse is suppressed by more than 70 dB. When this cavity is driven by a 20-kW source, output pulses with 200-kW peak power, 5-ns pulse width, and sub-nanosecond rise time can be obtained. We have also built an s-band cavity that has produced pulses of 5-ns width, 200-MW peak power, and under 3-ns rise time. The s-band cavity is typically driven at 5–10 MW and has a prepulse that can be more than 80 dB below the peak of the main pulse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139096
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  • 3
    Electronic Resource
    Electronic Resource
    Some properties of microwave resonant cavities relevant to pulse-compression power amplification (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2481-2488 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: One method of generating short, high-power microwave pulses is to store rf energy in a resonant cavity over a relatively long fill time and extract it rapidly. With this pulse compression technique power gain roughly equal to the ratio of fill time to extraction time can be obtained. During the filling of a resonant cavity some of the energy is lost in heating the cavity walls, and some will generally be reflected at the input coupling of the cavity. In this paper, we discuss the time dependence of the stored energy and related quantities and the way in which it depends on the coupling of the source to the cavity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139097
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  • 4
    Electronic Resource
    Electronic Resource
    Theory of intense electromagnetic pulse propagation through the atmosphere (1986)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 1238-1244 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A set of fluid equations is derived to describe the interaction of a very strong electromagnetic pulse with a weakly ionized plasma. These equations are used to investigate the dynamic behavior of an intense electromagnetic pulse propagating through the atmosphere. Results show that the amount of energy transmitted through the medium depends very strongly on the initial energy of the pulse and such characteristics and its frequency, its shape, and its length. In addition, a pulse was propagated through an air filled waveguide to verify the acuracy of the theoretical model. The theory also predicts very accurately the pulse breakdown threshold.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865872
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  • 5
    Electronic Resource
    Electronic Resource
    Electrophoretic behaviour of calcium oxalate monohydrate in liquid mixtures (1985)
    Springer
    Colloid & polymer science 263 (1985), S. 941-947 
    Details
    ISSN: 1435-1536
    Keywords: Electrophoretic mobility ; calcium oxalate monohydrate ; liquid mixture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An experimental investigation on electrophoresis of calcium oxalate monohydrate in several liquid mixtures (methanol-, ethanol-, 2-propanol-, and methanol-acetonewater) is described. The electrophoretic transport is considered from the view-point of the Thermodynamics of Irreversible Processes. Linear relations have always been found between the mass flux and the applied electric field. The ζ-potential of the interface C.O.M./liquid mixture has been estimated by using the classial theory of electrophoretic mobility of colloidal particles. The influence of the composition of the mixture on the electrophoretic coefficient has been discussed on the basis of the variation of ζ-potential, viscosity and dielectric constant with the molar fraction of alcohol for binary mixtures and acetone for ternary mixtures. The concentration dependence of the electrophoretic coefficient is found to be linear only in the latter case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01469634
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  • 6
    Electronic Resource
    Electronic Resource
    Photographic microdensitometry for evaluation of acid phosphatase activity at the electron microscope level (1986)
    Springer
    Journal of molecular histology 18 (1986), S. 481-486 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The dry mass of reaction products in ultrathin sections was determined using electron micrographs of polystyrene spheres of known weight deposited on Formvar membranes and evaluating the negatives photometrically. This method was applied to the quantification of the final reaction product of the acid phosphatase reaction in a model system in which enzyme was incorporated in gelatin. The enzyme activity was demonstrated by the lead precipitation method and quantified by direct microphotometry at the light microscope level. Models were then embedded and sectioned for electron microscopy. Microphotometric values afforded by the electron negatives were in linear correlation with incubation times and enzyme concentration. Section thickness and its possible variations due to deformation or contamination under the electron beam were also evaluated. Measurements of lysosomal acid phosphatase activity in rat kidney sections served to illustrate the application of the technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01675615
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  • 7
    Electronic Resource
    Electronic Resource
    Conformational changes of polyglutamic acid adsorbed on cationic polystyrene as characterized by microelectrophoresis technique (1989)
    Springer
    Colloid & polymer science 267 (1989), S. 853-856 
    Details
    ISSN: 1435-1536
    Keywords: Polystyrene ; polyglutamicacid ; electrophoreticmobility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polypeptides (polyglutamic acid in sodium form) of three different polymerization degrees have been adsorbed on cationic polystyrene latex. The electrokinetic behavior of the complex PG/PS has been studied by microelectrophoretic mobility. The effect of ionic strength and pH on electrokinetic properties of the complex PG/PS have also been studied. It has been found that the appearance of maximum inu e -logc curves is related to coverage degree of polystyrene surface and the polymerization degree of polypeptides chains. Likewise, the form of such curves depends markedly on pH. An attempt has been made to explain the data in terms of conformational changes of the adsorbed polypeptides chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410127
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  • 8
    Electronic Resource
    Electronic Resource
    Reduktive Arylierung von Vinyl-trifluoromethansulfonaten durch Friedel-Crafts-Reaktion (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1255-1256 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reductive Arylation of Vinyl Trifluromethanesulfonates by Friedel-Crafts ReactionThe reaction of vinyl triflates 1 with benzene and toluene in the presence of aluminium trichloride gives alkyl-, alkenyl-, and 1,1-diarylalkanes 5, 6, 3, 9 depending on the structure of the substrate used. A mechanism for the reductive arylation is proposed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200724
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  • 9
    Electronic Resource
    Electronic Resource
    Coke oven gas control by one-line gas chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 611-616 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Coke oven gas evolution ; On-line gas analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatograph will thermal conductivity detector (TCD) connected on line via a cleaning train to the semi-industrial scale Coke Oven Text Plant of the Spanish National Coal Institute (INCAR), has been used to control the evolution of the permanent gases during the coking process. The undesirable presence of oxygen in the coke oven gas can be detected with this system that will be applied to determine the end of the coking process by quantitative analysis of the gas evolved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02258988
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  • 10
    Electronic Resource
    Electronic Resource
    The cationic polymerization of 2-alkenyl furans. V. Kinetic of the polymerization of 2-ethenyl furan (1989)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 613-618 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Kinetische Untersuchungen der durch Trifluoressigsäure katalysierten Polymerisation von 2-Ethenyl-furan in Methylendichlorid zeigten ein Verhalten von pseudo-zweiter Ordnung mit Abweichungen in Richtung erster oder dritter Ordnung in Abhängigkeit vom Konzentrationsbereich des Initiators. Die Geschwindigkeitskonstante ist direkt proportional der Ausgangskonzentration des Initiators und umgekehrt proportional zur Ausgangskonzentration des Monomers. Während der Polymerisation nimmt die Säurekonzentration infolge der Bildung stabiler polymerer Ionen ab. Weiterhin wird vom Beginn der Polymerisation an eine alkylierung des Furanrings beobachtet. Zur Erklärung der experimentellen Ergebnisse wird ein pseudo-Copolymerisationsmechanismus vorgeschlagen.
    Notes: The kinetic studies of 2-ethenyl furan polymerization in methylene dichloride catalyzed by trifluoroacetic acid, showed a pseudo second order behaviour with deviations to the first or third order in dependence on the concentration range of the initiator. The rate constant is directly proportional to the square of the initial concentration of initiator and inversely proportional to the initial concentration of monomer. During the polymerization the acid concentration decreases as a consequence of the formation of stable polymeric ions. Moreover, the alkylation of furan ring from the beginning of the polymerization is observed. A pseudo-copolymerization mechanism is proposed to justify the experimental results.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1989.010400915
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