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  • 1
    Electronic Resource
    Electronic Resource
    Rubidium clock sound velocity meter (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 4679-4680 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A precision sound velocity meter has been made by adding a high stability rubidium oscillator to pulsed ultrasound instrumentation, where its stability and low noise is utilized as a quality time scale and a master clock, to which major timing events such as sound excitation, scope triggering, and time measurements are synchronized. Measuring operations are computer controlled. A reproducibility of ±0.005 m s−1 has been achieved in applications in research chemistry. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1322573
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  • 2
    Electronic Resource
    Electronic Resource
    An automated apparatus for ultrasound velocity measurements improving the pulse-echo-overlap method to a precision better than 0.5 ppm in liquids (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1644-1648 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An improvement of the pulse-echo-overlap (PEO) method is proposed to make it accessible for computer control. The modification makes it possible to avoid the systematic and subjective errors of the original PEO method. A digital oscilloscope and a frequency synthesizer is controlled by a personal computer providing a fast automatic method for determination of ultrasonic wave transit times. Description of the method and the computer program, as well as the technical parameters is given. The Panametrics 5053A ultrasonic time intervalometer has been slightly modified to be applicable in the new configuration with a better precision. The 0.5 ppm precision velocity determination in water requires a 0.0003 °C level temperature control and reproducible wettability of the surface of the transducer. For both problems, a practical solution is proposed. Error analysis shows that the reproducibility of measurements is within 0.5 ppm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144853
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  • 3
    Electronic Resource
    Electronic Resource
    Thermodynamic properties of peptide solutions. Part 15. Partial molar isentropic compressibilities of some glycyl dipeptides in aqueous solution at 15 and 35°C (1996)
    Springer
    Journal of solution chemistry 25 (1996), S. 1041-1053 
    Details
    ISSN: 1572-8927
    Keywords: Partial molar isentropic compressibility ; temperature dependence ; speed of sound ; dipeptide ; aqueous solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The partial molar isentropic compressibilities at infinite dilution,K s,2 o , have been obtained for eight glycyl dipeptides of sequence gly-X (X is an amino acid) in aqueous solution at the temperatures 15 and 35°C. The results have been combined with those obtained at 25°C, that were reported earlier, to evaluate the temperature dependences ofK s,2 o for the dipeptides in the temperature range 15 to 35°C. TheK s,2 o values for all the dipeptides are negative and increase (become more positive) with an increase in temperature. The slopes of the temperature dependences ofK s,2 o for the dipeptides with typically hydrophobic side-chains are significantly larger than those for dipeptides with hydrophilic side-chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00972920
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  • 4
    Electronic Resource
    Electronic Resource
    Thermodynamics of aqueous mixtures of 2-(2-Hexyloxyethoxy)ethanol at 5°C (1993)
    Springer
    Journal of solution chemistry 22 (1993), S. 1041-1062 
    Details
    ISSN: 1572-8927
    Keywords: Excess quantities ; reduced and apparent excess quantities ; molar volume ; molar isentropic compressibility ; ultrasonic speed ; alkyl poly(ethyleneglycol) monoether
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The densities and the ultrasonic speeds of the aqueous solutions of 2-(2-hexyloxyethoxy)ethanol (C6E2) were measured over the entire range of mole fractions at 5°C. Excess molar volumes V E were readily calculated from the densities. The densities, in combination with the ultrasonic speeds, furnish estimates of the molar (and excess molar) isentropic compressibilities K S and the deviations u D of the ultrasonic speeds from the values calculated for ideal mixtures. Radical changes in the mole fraction derivatives of the excess molar properties of the (C6E2 + water) system, in the vicinity of an amphiphile mole fraction of 0.003, indicate that C6E2 like C6E3 is capable of micelle formation. Our data have been compared with those reported earlier for (C4E2 +, C2E2 +, and C6E3 + water). We have employed both mass action and pseudophase approaches to data analysis, together with the four-segment model approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00647728
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