| 1. |
- Andersson, S. Peter, et al.
(författare)
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Relaxation Studies of Poly(propylene glycol) under High Pressure
- 1998
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 31:9, s. 2999-3006
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pressure on the relaxation processes in poly(propylene glycol) of number-average molecular weights 400 and 4000 g mol-1 (PPG-400 and PPG-4000) has been investigated using dielectric spectroscopy as well as thermal conductivity and heat capacity measurements. The relaxations associated with segmental motions within the polymer chain (α relaxation) and whole chain motions (α' relaxation) have been studied in the temperature range 200-400 K for pressures up to 2 GPa. The two processes display slightly different sensitivities to pressure, and as a consequence, are better separated at high pressures. As a result, high-pressure data exhibit the α' relaxation also in PPG-400, whereas previous investigations at atmospheric pressure have detected it only in PPG of molecular weights above about 1000 g mol-1. At atmospheric pressure, the values for (∂T/∂p)τ=1s of the alpha relaxation are, respectively, 140 and 192 K GPa-1 for PPG-400 and PPG-4000, where τ is the relaxation time. Because of the difference in (∂T/∂p)τ, the relaxation of the α motions and therefore the glass-transition temperature exhibits a more significant dependence on molecular weight at high pressures. At 295 K and 0.3 GPa, the activation volumes for the α and α' processes of PPG-4000 are about the same (approximate to 45 cm3 mol-1). At the same conditions, the activation volume for the α process of PPG-400 is about half of that for PPG-4000. An analysis of the α relaxation in terms of the strong-fragility classification shows that the degree of fragility of both PPG-400 and PPG-4000 increases slightly with increasing pressure.
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| 2. |
- Andersson, S. Peter, et al.
(författare)
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Thermal conductivity, heat capacity, and compressibility of atactic poly(propylene) under high pressure
- 1997
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Ingår i: International journal of thermophysics. - : Springer Science and Business Media LLC. - 0195-928X .- 1572-9567. ; 18:3, s. 845-864
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity λ and the heat capacity per unit volume of atactic poly(propylene) have been measured in the temperature range 90–420 K at pressures up to 1.5 GPa using the transient hot-wire method. The bulk modulus has been measured in the range 200–295 K and up to 0.7 GPa. These data were used to calculate the volume dependence of λ, g=−[∂λ/λ)/(∂V/V)]T, which yielded the following values for the glassy state (T<256 K at atmospheric pressure): 3.80±0.19 at 200 K, 3.74±0.19 at 225 K, 3.90±0.20 at 250 K, 3.77±0.19 at 271 K, and 3.73±0.19 at 297 K. The resultant value for g of the liquid state was 3.61±0.15 at 297 K. Values for g which are calculated at 295 K, using theoretical models of λ(T), agree to within 12% with the experimental value for the glassy state.
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| 3. |
- Andersson, S. Peter, et al.
(författare)
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Thermal conductivity of amorphous Teflon (AF 1600) at high pressure
- 1997
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Ingår i: International journal of thermophysics. - : Springer Nature. - 0195-928X .- 1572-9567. ; 18:1, s. 209-219
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity, λ, of amorphous Teflon AF 1600 [poly(1,3-dioxole-4,5-difluoro-2,2-bis(trifluoromethyl)-co-tetrafluoroethylene)] has been measured at pressures up to 2 GPa in the temperature range 93–392 K. At 295 K and atmospheric pressure, we obtained λ=0.116 W·m−1·K−1. The bulk modulus was measured up to 1.0 GPa in the temperature range 150–296 K and the combined data yielded the following values of g=(∂ln λ/∂ln V)T :2.8±0.2 at 296 K, 3.0±0.2 at 258 K, 3.0±0.2 at 236 K, 3.4±0.2 at 200 K, and 3.4±0.2 at 150 K.
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| 4. |
- Andersson, S. Peter, et al.
(författare)
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Volume dependence of thermal conductivity and bulk modulus for poly(propylene glycol)
- 1998
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Ingår i: Journal of Polymer Science Part B. - : John Wiley & Sons. - 0887-6266 .- 1099-0488. ; 36:2, s. 345-355
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity λ and heat capacity per unit volume of poly(propylene glycol) PPG (0.4 and 4.0 kg.mol-1 in number-average molecular weight) have been measured in the temperature range 150-295 K at pressures up to 2 GPa using the transient hot-wire method. At 295 K and atmospheric pressure, λ = 0.147 W m-1K-1 for PPG (0.4 kg.mol-1) and λ = 0.151 W m-1K-1 for PPG (4.0 kg.mol-1). The temperature dependence of λ is less than 4 x 10-4 W m-1K-2 for both molecular weights. The bulk modulus has been measured in the temperature range 215-295 K up to 1.1 GPa. At atmospheric pressure, the room temperature bulk moduli are 1.97 GPa for PPG(0.4 kg.mol-1) and 1.75 GPa for PPG (4.0 kg.mol-1). These data were used to calculate the volume dependence of λ, g = -((∂λ/λ)/(∂V/V))T. At room temperature and atmospheric pressure (liquid phase) we find g = 2.79 for PPG (0.4 kg.mol-1) and g = 2.15 for PPG (4.0 kg.mol-1). The volume dependence of g, (∂g /∂ log V)T varies between -19 to -10 for both molecular weights. Under isochoric conditions, g is nearly independent of temperature. The difference in g between the glassy state and liquid phase is small and just outside the inaccuracy of g of about 8%. The theoretical model for λ by Horrocks and McLaughlin yields an overestimate of g by up to 120%.
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| 5. |
- Andersson, S. Peter, et al.
(författare)
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Volume dependence of thermal conductivity and isothermal bulk modulus up to 1 GPa for poly(vinyl acetate)
- 1998
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Ingår i: Journal of Polymer Science Part B. - : John Wiley & Sons. - 0887-6266 .- 1099-0488. ; 36:9, s. 1451-1463
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity λ and heat capacity per unit volume of poly(vinyl acetate) (260 kg mol-1 in weight average molecular weight) have been measured in the temperature range 150-450 K at pressures up to 1 GPa using the transient hot-wire method, which yielded λ = 0.19 W m-1 K-1 at atmospheric pressure and room temperature. The bulk modulus K has been measured in the temperature range 150-353 K up to 1 GPa. At atmospheric pressure and room temperature, K = 4.0 GPa and (∂K/∂p)T = 8.3. The volume data were used to calculate the volume dependence of λ,g = -((∂λ/λ)/(∂V/V))T.The values for g of the liquid and glassy states were 3.0 and 2.7, respectively, and g of the latter was almost independent of volume and temperature. Theoretical models can predict the value for g of the glassy state to within 25%.
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| 6. |
- Andersson, S. Peter
(författare)
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Pressure and volume dependence of thermal conductivity and isothermal bulk modulus up to 1 GPa for poly(isobutylene)
- 1998
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Ingår i: Journal of Polymer Science Part B. - : John Wiley & Sons. - 0887-6266 .- 1099-0488. ; 36:10, s. 1781-1792
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity λ and heat capacity per unit volume ρcp of poly(isobutylene)s, one 2.8 in weight average molecular weight and one 85 kg mol-1 in viscosity average molecular weight (PIB-2800 and PIB-85000), have been measured in the temperature range 170-450 K at pressures up to 2 GPa using the transient hot-wire method. At 297 K and atmospheric pressure, λ = 0.115 W m-1 K-1 for PIB-2800 and λ = 0.120 W m-1 K-1 for PIB-85000. The bulk modulus BT has been measured in the temperature range 170-297 K up to 1 GPa. At atmospheric pressure, the room temperature bulk moduli BT are 2.0 GPa for PIB-2800 and 2.5 GPa for PIB-85000 with dBT/dp = 10 for both. These data were used to calculate the volume dependence of λ,g = -(∂λ/λ / ∂V/V)T.At room temperature and atmospheric pressure (liquid phase) we find g = 3.4 for PIB-2800 and g = 3.9 for PIB-85000, but g depends strongly on temperature for both molecular weights. The difference in g between the glassy state and liquid phase is small and just outside the inaccuracy of g of about 8%. The best predictions for g are given by the theoretical model of Horrocks and McLaughlin. We have found that PIE exhibits two relaxations, where one is associated with the glass transition. The value for dTg/dp at atmospheric pressure (for the main glass transition) is about 0.21 K MPa-1 for both molecular weights.
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| 7. |
- Riise, Gerdt C., 1956, et al.
(författare)
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Bronchial inflammation in chronic bronchitis assessed by measurement of cell products in bronchial lavage fluid
- 1995
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Ingår i: Thorax. - 0040-6376. ; 50:4, s. 360-5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND--Bronchial inflammation in chronic bronchitis has not been characterised as well as in asthma. The present study was undertaken to assess whether a characteristic pattern of bronchial inflammatory markers could be found in patients with chronic bronchitis. METHODS--Bronchoscopy with bronchial lavage was performed in 42 patients with chronic bronchitis and in 13 healthy controls. Twenty three of the patients had non-obstructive chronic bronchitis and 19 had chronic bronchitis and chronic obstructive pulmonary disease (COPD). Eighteen of the patients with bronchitis had recurrent infective exacerbations and 24 did not. Intrabronchial bacterial cultures were taken with a protected specimen brush. RESULTS--Increased activity of neutrophils, fibroblasts, and eosinophils was found in the patients with chronic bronchitis as assessed by the levels of myeloperoxidase (MPO) and interleukin-8 (IL-8), hyaluronan, and eosinophil cationic protein (ECP), respectively. The levels of tryptase did not differ from the controls. High correlations were found between the levels of MPO and IL-8, as well as ECP and IL-8. No differences were found between the patients with COPD and those with non-obstructive chronic bronchitis. CONCLUSIONS--Recruitment and activation of both neutrophils and eosinophils seem to be a characteristic of chronic bronchitis. This activation is associated with IL-8. The patients with intrabronchial cultures of Streptococcus pneumoniae had the highest individual levels of MPO, ECP, and IL-8 of all subjects in the study, indicating that colonisation with S pneumoniae could promote bronchial inflammation.
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| 8. |
- Stenman, U H, et al.
(författare)
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Summary report of the TD-3 workshop: characterization of 83 antibodies against prostate-specific antigen
- 1999
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Ingår i: Tumor Biology. - : Springer Science and Business Media LLC. - 1423-0380 .- 1010-4283. ; 20:Suppl. 1, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Twelve research groups participated in the ISOBM TD-3 Workshop in which the reactivity and specificity of 83 antibodies against prostate-specific antigen (PSA) were investigated. Using a variety of techniques including cross-inhibition assays, Western blotting, BIAcore, immunoradiometric assays and immunohistochemistry, the antibodies were categorized into six major groups which formed the basis for mapping onto two- and three-dimensional (2-D and 3-D) models of PSA. The overall findings of the TD-3 Workshop are summarized in this report. In agreement with all participating groups, three main antigenic domains were identified: free PSA-specific epitopes located in or close to amino acids 86-91; discontinuous epitopes specific for PSA without human kallikrein (hK2) cross-reactivity located at or close to amino acids 158-163; and continuous or linear epitopes shared between PSA and hK2 located close to amino acids 3-11. In addition, several minor and partly overlapping domains were also identified. Clearly, the characterization of antibodies from this workshop and the location of their epitopes on the 3-D model of PSA illustrate the importance of selecting appropriate antibody pairs for use in immunoassays. It is hoped that these findings and the epitope nomenclature described in this TD-3 Workshop are used as a standard for future evaluation of anti-PSA antibodies.
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