| 1. |
- Andersson, Göran, et al.
(författare)
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Electrical resistivity measurements under hydrostatic conditions up to 10 GPa
- 1984
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Ingår i: Journal de Physique Colloques vol. 45. - : EDP Sciences. - 0449-1947. ; , s. 379-382
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Konferensbidrag (refereegranskat)abstract
- A large scale Bridgman anvil system has been designed. Steel gaskets permit compression of a methanol-ethanol medium over a volume of 500-250 mm3. Up to 12 wires have been used to contact specimens. The system has so far served up to 7.5 GPa, with anvils made of ASP tool steel. The transition Bi III-V was found to occur at a lower pressure than the recommended average. The electrical resistance of copper was measured up to 6 GPa under hydrostatic conditions.
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| 2. |
- Hafström, Larsolof, et al.
(författare)
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Influence of vasoactive drugs on blood flow in subcutaneous tumors – an experimental study in rats
- 1980
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Ingår i: Journal of Surgical Oncology. - : Wiley. - 0022-4790 .- 1096-9098. ; 14:4, s. 359-366
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Tidskriftsartikel (refereegranskat)abstract
- Subcutaneously implanted tumors in Wistar and Lister rats were used as a model for the study of metastatic tumor blood flow and how it is affected by vasoactive drugs. Blood flow measurements were obtained using the labelled microsphere method and the reference organ technique. Microspheres (15‐μm) labelled with either 99Tcm or 51 Cr isotopes were injected intracardially and a reference sample was drawn simultaneously at constant speed. This was performed before and after the infusion of vasoactive drugs, and (as control), saline infusion. The drugs tested (adrenaline, noradrenaline, glucagon, histamine, and vasopressin) showed profound effects on central hemodynamic parameters and on muscle and skin blood flow. The relative tumor blood flow, measured as the ratio between tumor and skin or tumor and muscle blood flow, was calculated. The results show that no enhancement of the relative tumor blood flow could be registered. In fact, a decrease in the tumor‐to‐muscle‐blood‐flow ratio was noted when noradrenaline was infused, and in the tumor‐to‐skin ratio when adrenaline was infused. Blood flow in subcutaneous tumors was four to five times that in muscle or skin. Tumor blood flow was also inversely related to the size of the tumor.
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| 3. |
- Lundberg, Bo, et al.
(författare)
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Pressure effects on electrical conductivities in intercalated graphite and doped polypyrrole
- 1984
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Ingår i: Journal de Physique Colloque vol. 45. - : EDP Sciences. - 0449-1947. ; , s. 213-216
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Konferensbidrag (refereegranskat)abstract
- We have measured the pressure dependence up to 2.5 GPa of the electrical resistance of the acceptor intercalated graphites CnFeCl3, CnSbF5, and CnHNO3. The slope of resistance versus pressure is approximately the same in all cases. Two different types of high pressure transitions are observed in CnSbF5 and CnHNO3. The results of electrical resistance measurements under pressure in polypyrrole are consistent with a simple extension of the variable-range-hopping model. We infer for this material that the density of states at the Fermi level increases with pressure.
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| 4. |
- Neve, Jesper, et al.
(författare)
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Electron band structure, resistivity, and the electron-phonon interaction for niobium under pressure
- 1983
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 28:2, s. 629-637
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Tidskriftsartikel (refereegranskat)abstract
- Accurate measurements of the electrical resistance of Nb are presented as a function of temperature and pressure in the region 0-40°C and 0-1 GPa. From these measurements and published results for the compressibility and the pressure dependence of the superconducting transition temperature Tc we evaluate the pressure dependence of the electron-gas plasma frequency ω(p). The electronic structure of Nb is calculated from a self-consistent linear muffin-tin orbital method and results are obtained for the pressure dependence of the density of states at the Fermi surface, the root mean square over the Fermi surface of the Fermi velocity, the optical mass, and the plasma frequency. The experimental and calculated results for the pressure dependence of ω(p) are both close to dlnω2 / dlnV=-1.9. This agreement suggests that measurements of the electrical resistance as a function of temperature and pressure provide a new test of band-structure calculations. From our measurements of the resistance and calculations of ω(p) and from published results for the compressibility we obtain the pressure dependence of the electron-phonon interaction λ(p). With p given in gigapascals, the result is dlnλ / dp=-0.0047.
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| 5. |
- Rapp, Östen, et al.
(författare)
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Possibility of superconductivity in palladium at high pressures
- 1984
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Ingår i: LT-17. - Amsterdam : North-Holland: Elsevier Science Publishers B.V.. - 0444869107 ; , s. 865-866
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Konferensbidrag (refereegranskat)abstract
- On the basis of measurements of the resistivity and calculations of the density of states and the plasma frequency it is concluded that palladium may become superconducting at high pressures.
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| 6. |
- Rapp, Östen, et al.
(författare)
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The pressure dependence of of the electron-phonon interaction and the normal state resistivity
- 1981
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 24:1, s. 144-154
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Tidskriftsartikel (refereegranskat)abstract
- Accurate measurements of the electrical resistance as a function of temperature and pressure are reported for Sn, Zr, dhcp La, and V. These measurements cover a temperature region around room temperature and pressures up to 1.3 GPa. From these data, including also our previous measurements for Al and published results for Pb, the pressure dependence of d ρ / dT (the resistivity-temperature derivative) is obtained. This quantity is found to be a significant factor in the pressure dependence of the electron-phonon interaction parameter λ. For the nontransition metals the relative pressure dependence of d ρ / dT is much larger than the compressibility. Therefore the pressure dependence of the superconducting Tc is quantitatively well accounted for by the resistance data for these metals. For the transition metals the pressure dependence of d ρ / dT is relatively smaller and Tc(p) calculated from the resistance data is, at the best, only qualitatively correct. These differences are discussed. Estimates for the pressure dependence of the plasma frequency are obtained.
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| 7. |
- Ross, Russel George, et al.
(författare)
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Thermal conductivity of solids and liquids under pressure
- 1984
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Ingår i: Reports on progress in physics (Print). - : IOP Publishing. - 0034-4885 .- 1361-6633. ; 47:10, s. 1347-1402
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Forskningsöversikt (övrigt vetenskapligt/konstnärligt)abstract
- Thermal conductivity of solids and liquids under pressure is covered in this review. Experimental techniques are critically considered and compared, and an introduction to theory is provided. Results are presented and discussed for ionic crystals, normal molecular crystals, plastic crystal phases, clathrate hydrates, polymers and glass-formers, liquids, covalent and semiconducting crystals, rocks and metals. Special attention is given to isochoric conditions, change of crystal structure and molecular orientational disorder. Available reliable measurements at pressures up to a few GPa indicate the need for theoretical development, especially in connection with molecular crystals and ferromagnetic metals.
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| 8. |
- Sandberg, Olov, et al.
(författare)
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Thermal properties of two low viscosity silicone oils as functions of temperature and pressure
- 1982
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Ingår i: Journal of Applied Physics. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 53:12, s. 8751-8755
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity and the specific heat capacity per unit volume have been measured for two low viscosity grades of Dow Corning 200 fluid (polydimethyl siloxane) in the range 110 to 350 K and under pressures up to 2.0 GPa (20 kbar). Both the quantities studied are found to increase with increasing pressure in the liquid phase. From the measured data the phase diagrams are obtained. The 5 mm2/s (5 cSt) grade fluid does not crystallize, but undergoes a glass transition at 1.0 GPa at room temperature. The 1 mm2/s (1 cSt) grade has a more complicated phase diagram with a partly crystalline phase at low temperatures and pressures and two glass transitions at high temperatures and pressures.
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| 9. |
- Sundqvist, Bertil, et al.
(författare)
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Contactless measurements of the basal plane resistivity of FeCl3 and SbF5 intercalated graphites under pressure
- 1984
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Ingår i: Journal of Physics C: Solid State Physics. - : IOP Publishing. - 0368-3516 .- 0022-3719. ; 17:5, s. L133-L138
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Tidskriftsartikel (refereegranskat)abstract
- The basal plane resistivities of stage 1 SbF5 and stage 2 FeCl3 graphite intercalation compounds have been measured for the first time at high pressure, using a recently developed contactless method. The resistivity is found to increase with increasing pressure in both materials. In the SbF5 intercalated material a phase transition was found at 1.2 GPa. This could be the first pressure-induced stage transformation observed in an acceptor intercalation compound.
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| 10. |
- Sundqvist, Bertil, et al.
(författare)
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Contactless methods for measuring electrical resistivity under pressure
- 1984
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Ingår i: High Pressure in Science and Technology, Part III: General Topics. - New York : North-Holland, Elsevier Science Publishing Co., Inc.. - 0444009310 - 0444009329 ; , s. 281-284
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Konferensbidrag (refereegranskat)abstract
- A new inductive contactless method to measure the electrical conductivity of metals under pressure is described. A ferromagnetic Metglas 2826 toroid core is used to minimize errors due to external magnetic fields. Experimental results for tin and brass are shown to agree very well with conventional four-terminal measurements.
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