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- Aleksandrovskii, A. N., et al.
(författare)
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Low-temperature thermal expansion of pure and inert gas-doped fullerite C60
- 2003
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Ingår i: Fizika Nizkikh Temperatur (Kharkov). - : AIP Publishing. - 0132-6414 .- 1816-0328. ; 29:4, s. 432-442
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Tidskriftsartikel (refereegranskat)abstract
- The low temperature (2–24 K) thermal expansion of pure (single-crystal and polycrystalline) C60 and polycrystalline C60 intercalated with He, Ne, Ar, and Kr has been investigated using the high-resolution capacitance dilatometer. The investigation of the time dependence of the sample length variations deltaL(t) on heating by deltaT shows that the thermal expansion is determined by the sum of positive and negative contributions, which have different relaxation times. The negative thermal expansion usually prevails at helium temperatures. The positive expansion is connected with the phonon thermalization of the system. The negative expansion is caused by reorientation of the C60 molecules. It is assumed that the reorientation is of a quantum character. The inert gas impurities affect the reorientation of the C60 molecules very strongly, especially at liquid helium temperatures. A temperature hysteresis of the thermal expansion coefficient of Kr– and He–C60 solutions has been revealed. The hysteresis is attributed to orientational polyamorphous transformation in these systems.
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- Jonsson, S W, et al.
(författare)
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Increased prevalence of atherosclerosis in patients with medium term rheumatoid arthritis
- 2001
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Ingår i: Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 28, s. 2597-2602
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To measure the extent of atherosclerosis in patients with rheumatoid arthritis (RA) with a disease duration of considerable length, and in age and sex matched individuals. Methods. Thirty-nine patients with RA (30 women, 9 men) with disease onset occurring between 1974 and 1978, and less than 65 years of age at the time of investigation, were enrolled together with 39 sex and age matched controls. Quantitative measurement of intima-media thickness (IMT) and semiquantitative assessment of the presence of plaque were undertaken by B-mode ultrasound of the common carotid artery (CCA-IMT) and the common femoral artery on the right-hand side. Echo Doppler cardiography was performed with an Accuson Aspen. The results were related to disease activity variables and accumulated disease activity, to lipid levels [i.e., cholesterol, high density lipoproteins, low density lipoproteins, triglycerides (TG)], to hemostatic factors [tissue plasminogen activator antigen (tPAag), plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (vWF)], and to soluble adhesion molecules (sICAM-1 and sE-selectin). Results. Patients with RA had higher maximal and mean IMT values compared with controls. The difference concerning mean CCA-IMT reached statistical significance in patients with RA and correlated significantly with lipids (cholesterol, LDL, LDL/HDL ratio, TG) and tPAag. The prevalence of plaques, as well as of aortic cusp sclerosis, was higher in RA but only the difference in aortic cusp sclerosis was statistically significant. Patients with plaques had significantly higher levels of lipids (cholesterol, LDL, LDL/HDL ratio) than patients without plaques, while patients with cusp sclerosis had significantly higher cholesterol and TG levels. sICAM-1 was significantly higher both in patients with plaques and in those with aortic cusp sclerosis compared to patients without. Conclusion. Our results suggest an accelerated atherosclerosis in patients with RA that is related mainly to lipid levels.
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- Makarova, Tatiana L, et al.
(författare)
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Conductivity of two-dimensional C60 polymers
- 2000
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Ingår i: Proceedings of the 4th International Workshop on Fullerenes and Atomic Clusters (IWFAC'99), St. Petersburg 1999. - : Overseas Publishers Association N.V.. ; , s. 151-156
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Konferensbidrag (refereegranskat)abstract
- The general trend in the shift of electronic properties as the result of polymerization has been studied with the aid of temperature dependences of conductivity. Samples representing the pure rhombohedral phase exhibit great anisotropy in their electrical properties. The main features of the behaviour of these samples are: (i) in the z-direction the resistivity is of the order of several kOhm cm and decreases with temperature; (ii) in the x-y direction resistivity is less than 1 Ohm cm and shows a minimum at a certain temperature.
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