| 1. |
- Andersson, Per, et al.
(författare)
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Pressure dependence of the thermal conductivity, thermal diffusivity, and specific heat of some polymers
- 1975
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Ingår i: Journal of Polymer Science Polymer Physics Edition. - : Wiley. - 1542-9385 .- 0098-1273. ; 13:2, s. 243-251
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Tidskriftsartikel (refereegranskat)abstract
- The pressure dependence of the specific heat of poly(methyl methacrylate), polystyrene, and atactic and isotactic polypropylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300°K and in the pressure range 0-37 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, while the specific heat decreases. The pressure dependencies are most pronounced at low pressures. The results are compared with other experimental results and with theoretical calculations.
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| 2. |
- HAFSTRÖM, LARSOLOF, et al.
(författare)
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Measurements of cardiac output and organ blood flow in rats using 99Tcm labelled microspheres
- 1979
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 106:2, s. 123-128
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Tidskriftsartikel (refereegranskat)abstract
- The cardiac output and regional blood flow have been simultaneously determined in the anesthetized rat by using the reference organ method. 99Tcm labelled dextran 15 μm microspheres were injected in the left ventricle while simultaneously an arterial reference sample was drawn at constant known rate. The values calculated regarding cardiac output agree well with previously recorded series. Regional organ blood flow in the rat is presented as ml. min‐1. g‐1 tissue and values do agree with those reported by others. The results indicate that the reference organ method can be used in the rat for the study of cardiac output and regional blood flow.
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| 3. |
- Sundqvist, Bertil, et al.
(författare)
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Low noise and drift by parallel amplifiers
- 1975
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics. - 0034-6748 .- 1089-7623. ; 46:7, s. 928-929
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Tidskriftsartikel (refereegranskat)abstract
- A low noise and low drift amplifier has been constructed using several monolithic operational amplifiers in parallel. It is shown that each amplifier may be connected by only three resistors. An input noise of 0.15 µV (p–p) in the band 0.1–10 Hz was obtained with six amplifiers, and the noise is expected to decrease as N−1/2 as the number of units is increased.
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| 4. |
- Sundqvist, Bertil, et al.
(författare)
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Measurement of the pressure dependence of the electron-phonon interaction in aluminium
- 1979
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Ingår i: Journal of Physics F: Metal Physics. - Bristol : Institute of Physics. - 0305-4608. ; 9:9, s. L161-L166
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Tidskriftsartikel (refereegranskat)abstract
- The authors report measurements of the electrical resistance of aluminium in the temperature range 30-40 degrees C and the pressure range 0.2-1.0 GPa. From these experiments the pressure dependence of the electron-photon interaction lambda is evaluated. With p in GPa the result is lambda (p)= lambda 0 exp(-0.0467p+4.7*10-4 p2). This expression for lambda describes accurately the observed pressure dependence of the superconducting Tc for pressures up to about 4 GPa.
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| 5. |
- Sundqvist, Bertil, et al.
(författare)
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Pressure dependence of the thermal conductivity of aluminium
- 1977
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Ingår i: Solid State Communications. - : Elsevier B.V.. - 0038-1098 .- 1879-2766. ; 23:10, s. 773-775
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Tidskriftsartikel (refereegranskat)abstract
- The thermal diffusivity, a, of aluminium has been measured at pressures up to 2.5 GPa at room temperature, and from these results the pressure dependence of the thermal conductivity, λ, has been calculated. Both quantities increase with pressure. The increase in a amounts to 4.6% to 1 GPa and 10.4% to 2.5 GPa. The initial pressure coefficient of the electronic thermal conductivity λe is found to be [λe]-1λe/P = 3.7 × 10-2GPa-1, which agrees very well with a recent theoretical calculation.
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| 6. |
- Sundqvist, Bertil, et al.
(författare)
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The thermal properties of an epoxy resin at high pressure and temperature
- 1977
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Ingår i: Journal of Physics D. - Bristol : Institute of Physics. - 0022-3727 .- 1361-6463. ; 10:10, s. 1397-1403
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity lambda , thermal diffusivity and heat capacity per unit volume has been measured for an epoxy resin, Araldite AW 106, with hardener HV 953 U. Measurements have been carried out at room temperature up to 2.5 GPa and between 300 and 430K at 0.11 and 0.27 GPa. The glass transition temperature and its pressure (P) dependence have been determined. The quantity delta lambda / delta P was found to change abruptly in the temperature region of the glass transition.
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| 7. |
- Sundqvist, Bertil, et al.
(författare)
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Thermal conduction of metals under pressure
- 1976
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics. - 0034-6748 .- 1089-7623. ; 47:2, s. 177-182
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that the original Ångström method of determining the thermal diffusivity of metals is not valid in the case of a specimen surrounded by a solid medium, and an appropriate modification is described. Several simplifications of this method are also presented and criteria for their validity given. An electronic system has been developed for automatic sampling and analysis of the temperature data. The new method has been applied to Cu under pressure, and the results show that the thermal conductivity rises by 6.4% up to 2.5 GPa (25 kilobar).
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| 8. |
- Sundqvist, Bertil, et al.
(författare)
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Thermal conductivity of copper under high pressure
- 1977
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Ingår i: High Temperatures-High Pressures. - London : Pion Ltd. - 0018-1544 .- 1472-3441. ; 9:1, s. 41-48
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Tidskriftsartikel (refereegranskat)abstract
- The thermal diffusivity, a, of copper has been measured at room temperature up to a pressure of 2.5 GPa (25 kbar) by means of a method recently developed. In this pressure range the diffusivity increases linearly with a slope of (1/a)da/dp = 2.7x10-2 GPa-1. As the density and specific heat of copper are known as functions of pressure, this result can be used to obtain the pressure dependence of the thermal conductivity, lambda, with the result (1/lambda)d(lambda)/dp = 3.1x10-2 GPa-1. This value is shown to agree well with theoretical calculations of this slope. However, a comparison between this result and the pressure dependence of the electrical conductivity shows deviations from the Wiedemann-Franz law.
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| 9. |
- Sundqvist, Bertil, et al.
(författare)
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Thermal conductivity of gold and silver at high pressures
- 1978
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Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier B.V.. - 0022-3697 .- 1879-2553. ; 39:10, s. 1133-1137
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Tidskriftsartikel (refereegranskat)abstract
- The thermal diffusivities of gold and silver have been measured under pressure up to 2.5 GPa at room temperature. From the measured data the pressure dependence of the thermal conductivity, λ, has been calculated. The values found for the pressure coefficient λ−1 δλ/δP were 3.9 × 10−2GPa−1 for gold and 4.0 × 10−2 GP silver at atmospheric pressure. The results are compared to theoretical predictions of the pressure dependence and also to previous experimental results for copper and aluminium. For the noble metals, small angle or “vertical” scattering of electrons is shown to have a stronger volume dependence than “horizontal” scattering.
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| 10. |
- Sundqvist, Bertil, 1949-
(författare)
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Thermal conductivity of some metals under pressure
- 1978
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Although measurements of a wide variety of physical properties have been carried out under pressure during the last decades, data for thermal conductivity under pressure are sparse. This is especially so in the case of metals, where the experimental difficulties are very large. In this work a new method to make such measurements is presented, together with experimental results for copper, silver, gold, and aluminium at room temperature and pressures up to 2.5 GPa.The first part of the work describes in some detail the method used.This method is a variation of the well known Ångström method. The measured property is thus not the thermal conductivity, but instead the thermal diffusivity. Both the Ångström method, and the variation of this used in this work, are described in detail. Several further simplifications of the method are also investigated. The experimental equipment is described in detail, as is also the construction of samples and pressure cells.After a description of the experimental procedure, experimental results are presented for the thermal diffusivity of the metals studied, at pressures up to 2.5 GPa. These data are converted to thermal conductivity data by the use of available data on density and specific heat capacity for these metals under pressure. In a few cases, theoretically calculated values for the latter quantity are used. After a brief look at the theory for the thermal conductivity of metals, the experimental results are compared to simple theoretical predictions. The agreement is found to be good. Contrary to theoretical predictions, however, the electronic Lorentz function is found to increase with increasing pressure for the noble metals.
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