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  • 1
    Electronic Resource
    Electronic Resource
    A laser-induced fluorescence measurement technique for obtaining neutral hydrogen densities in plasmas (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 4595-4599 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The resonance fluorescence of neutral hydrogen illuminated by Hα radiation has been used as a technique for the spatially and temporally resolved density measurements of neutral hydrogen in high temperature plasmas, such as in the tokamak and magnetic mirror plasma fusion devices. The fluorescence signal, usually very weak and buried in the background of stray laser light and Hα emission, is very difficult to extract and its measurements are inaccurate. This paper discusses the improvement of the signal extraction using two optical path laser-induced fluorescence (LIF) methods. One optical path carries the fluorescence signal and the background (the stray laser light and Hα emission), whereas the other path carries only the background signal. By combining these two signals, a clean fluorescence signal can be isolated by subtracting out the background using a differential amplifier. The measurement is obtained instantaneously from these two signals which are taken simultaneously in one pulse rather than being extracted from two separate spectra taken in two sequential pulses (double pulses). This method, therefore, makes a significant improvement on the double pulse technique in terms of the accuracy of the measurement and the time resolution. Using this LIF technique the measurement of the neutral density profile in the exhaust of a tandem mirror plasma propulsion device is obtained and presented. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145295
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  • 2
    Electronic Resource
    Electronic Resource
    A double pendulum plasma thrust balance and thrust measurement at a tandem mirror exhaust (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 4637-4643 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For the purpose of measuring the plasma momentum flux in a plasma system, a highly sensitive and precision balance has been developed. It can measure a force, an impulse, or thrust as low as 0.1 mN free of mechanical noise, electrical and magnetic pickups. The double pendulum system consists of two parallel conducting plates. One or both of the plates can be suspended by needles. The needle suspended plate (or plates) can swing freely with negligible friction because of the sharp points of the needles. When one of the plates is impacted by an impulse it will swing relatively to the fixed plate or other movable plate. The capacitance between the plates changes as a result of such a motion. The change of capacitance as a function of time is recorded as an oscillating voltage signal. The amplitude of such a voltage signal is proportional to the impacting force or impulse. The proportional factor can be calibrated. The forces can thus be read out from the recorded value of the voltage. The equation of motion for the pendulum system has been solved analytically. The circuit equation for the electronic measurement system has been formulated and solved numerically. Using this balance the thrust at the exhaust of a Tandem Mirror plasma thruster has been measured. The analytical solution of the overall characteristics agrees greatly with the measurement. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146490
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  • 3
    Electronic Resource
    Electronic Resource
    Polymerization by phase transfer catalysis 22. Synthesis of poly(amide-carbonate)s and poly(amide-thiocarbonate)s derived from diphenols with the amide group in the side chain (1997)
    Springer
    Polymer bulletin 39 (1997), S. 9-14 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. Poly(amide-carbonate)s and poly(amide-thiocarbonate)s derived from the diphenol-amides N-(2,6-dichloro-4-nitrophenyl)-2,2-bis(hydroxyphenyl)-propylamide (I), N-(2,6-dichloro-4-nitrophenyl)-3,3-bis(hydroxyphenyl)-butylamide (II), and N-(2,6-dichloro-4-nitrophenyl)-4,4-bis(hydroxyphenyl)-pentylamide (III), and phosgene or thiophosgene, have been synthesized under phase transfer conditions using several quaternary ammonium salts as phase transfer catalysts. Benzyltriethylammonium chloride (BTEAC) was effective in practically all cases due the hydrophilicity of this catalysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002890050113
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  • 4
    Electronic Resource
    Electronic Resource
    Polymerization by phase transfer catalysis 23. Synthesis of poly(amide-ester)s derived from diphenols with the amide group in the side chain (1998)
    Springer
    Polymer bulletin 40 (1998), S. 35-42 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. The synthesis of poly(amide-ester)s derived from the diphenol-amides N-(2,6-dichloro-4-nitrophenyl)-2,2-bis(4-hydroxyphenyl)-propanamide, N-(2,6-dichloro-4-nitrophenyl)-3,3-bis(4-hydroxyphenyl)-butanamide, and N-(2,6-dichloro-4-nitrophenyl)-4,4-bis(4-hydroxyphenyl)-pentanamide and terephthaloyl chloride, isophthaloyl chloride and adipoyl chloride, is described under phase transfer conditions, using several quaternary ammonium salts as phase transfer catalysts. The behaviour of the catalysts was evaluated through the yields and inherent viscosity measurements and compared with those obtained without a catalyst. In general, the phase-transfer process was effective, and the best catalyst was benzyltriethylammonium chloride, which has hydrophilic characteristics and is suitable for transporting lypophilic dianions such as those used in this synthesis. Other catalysts also showed a good behaviour. All poly(amide-ester)s were insoluble in the reaction media, which limited their growth and the molecular weight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002890050220
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  • 5
    Electronic Resource
    Electronic Resource
    Polymerization by phase transfer catalysis (1996)
    Springer
    Polymer bulletin 36 (1996), S. 717-721 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Poly(amido-carbonate)s and poly(amido-thiocarbonate)s derived from 1,6-bis(4-hydroxyphenyl-carbamoyl)-hexamethylene I and 1,4-bis(4-hydroxyphenyl-carbamoyl)-phenylene II, and phosgene or thiophosgene, have been synthesized by a phase transfer catalysis process, which was ineffective for polymers derived from monomer I because the best results were obtained without catalyst, but was effective for those derived from monomer II obtaining higher yields when the catalysts were used. The ineffectivity was attributed to a hydrolytic process of the polymeric chains in the reaction media.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338635
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  • 6
    Electronic Resource
    Electronic Resource
    Polymerization by phase transfer catalysis (1984)
    Springer
    Polymer bulletin 11 (1984), S. 493-496 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Polyethers from 1,4-bis(chloromethylene)-2,5-dimethoxybenzene and 4,4′-biphenol were obtained by phase transfer catalysis, using different catalysts and solvents. The molecular weights and yields were determined, showing a solvent effect and a influence of the catalysts used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01045326
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  • 7
    Electronic Resource
    Electronic Resource
    Polymerization by phase transfer catalysis (1992)
    Springer
    Polymer bulletin 28 (1992), S. 645-652 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Polycarbonates, polythiocarbonates, and polyesters from 1,1,3-trimethyl-3-(4′-hydroxy-phenyl)-4-indanol were synthesized using phase transfer conditions. THe effects of several catalysts and reactions times were evaluated by the yields and inherent viscosities. Phase transfer catalysis was not an efficient technique due to the rigid structure of the diphenol with the indanic group. The results were compared with that obtained with a diphenol having the same number of carbon atoms but forming an aliphatic side chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295967
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  • 8
    Electronic Resource
    Electronic Resource
    A chelating polyamide (1983)
    Springer
    Polymer bulletin 10 (1983), S. 381-383 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A polyamide has been prepared by solution polymerization of 2,5-dihydroxyterephthaloyl dichloride and 4,4′-methylenedianiline. This polymer showed up chelating properties in presence of Cu (II) ion in aqueous solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00281952
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  • 9
    Electronic Resource
    Electronic Resource
    Polythiophene, polyaniline and polypyrrole electrodes modified by electrodeposition of Pt and Pt+Pb for formic acid electrooxidation (1998)
    Springer
    Journal of applied electrochemistry 28 (1998), S. 943-946 
    Details
    ISSN: 1572-8838
    Keywords: polythiophene ; polyaniline ; polypyrrole ; Pt modified polymer electrodes ; bimetallic(Pt + Pb)-modified polymer electrodes ; formic acid electrooxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The electrosynthesis of polythiophene (PTh), polyaniline (PANI) and polypyrrole (PPy) films modified by dispersion of Pt or Pt+Pb and its employment in the electrocatalytic oxidation of HCOOH are studied and compared. The influence of parameters such as polymer film thickness, the number of dispersed Pt particles, the amount of Pb deposited and the presence of Pb2+ in the electrolyte on the electrooxidation of HCOOH is investigated. Electrode systems including the polymer and a mixture of Pt and Pb particles show a better electrocatalytic activity than electrodes having a polymer–Pt combination or bulk Pt electrodes. Furthermore, during the electrooxidation of HCOOH using polymer–(Pt+Pb) electrodes the presence of fewer poisoning species is observed, indicating that the role of Pb in these electrode systems is in agreement with the Pb adatom effect observed when bulk Pt electrodes are used. However, the presence of Pb(ii) in the electrolyte is not required for the PTh–(Pt+Pb) electrode system and, in addition, a better electrocatalytic effect is obtained in this case. With application of an appropriate E/t program the activity is unchanged over a long time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003415805513
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and Characterization of Poly(amides) Derived from Diamines with Germanium and Silicon (2000)
    Springer
    Journal of inorganic and organometallic polymers and materials 10 (2000), S. 73-79 
    Details
    ISSN: 1572-8870
    Keywords: poly(amides) ; germanium ; silicon ; thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Poly(amides) (PAs) derived from bis(4-aminophenyl)-diphenylgermane and bis(4-aminophenyl)-diphenylsilane, and terephthaloyl, isophthaloyl, and tetrachloroterephthaloyl chlorides, were synthesized in N, N-dimethylacetamide solution. The products were characterized by IR and NMR spectroscopy. The results were in agreement with the proposed structures. The yields were almost-quantitative for PAs derived from terephthaloyl and isophthaloyl chlorides. However, the yields from the diacid tetrachloroterephthaloyl chloride were very low due to low reactivity. The inherent viscosity values of all PAs measured in o-chlorophenol were very similar. Thermogravimetric analysis indicated that the Ge-containing PAs were more stable than were those containing Si due to the higher polarity of the C–Si bond. The PAs derived from tetrachloroterephthaloyl chloride are exceptions owing to the influence of the chlorine atoms. The glass transition temperatures (T g) were determined for all the PAs. The PAs derived from the Si-containing diamine have a value higher than that for the Ge-containing diamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009471808202
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