| 1. |
- Johansson, K, et al.
(författare)
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The interactions between alkyd resin binders and kaolinite
- 1991
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Ingår i: Colloids and Surfaces. - 0166-6622 .- 1873-4340. ; 56, s. 313-338
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between alkyd resins and kaolinte has been studied by means of adsorption measurements and spectroscopic methods such as electron spectroscopy for chemical analysis (ESCA) and diffuse reflectance infrared Fourier transform spectroscopy. The interaction is mainly governed by Lewis acid-base interactions but the molecular weight distribution and the oil length of the alkyds are of great importance. The kaolinite surface appears to be amphoteric since both acidic and basic species are adsorbed. The alkyd resins are very polydisperse. The experimental results are in agreement with the prediction of the theory of Cohen Stuart et al. (M.A Cohen Stuart, J.M.H.M. Scheutjens and G.J. Fleer, J. Polym. Sci., Polym. Phys. Ed., 18(1980) 559) for adsorption of polydisperse polymers. The alkyds are strongly adsorbed on the kaolinite, but not aluminium or hydroxxyl groups next to the aluminium. Double bonds, orginationg from the fatty acid part of the alkyd, play an active role in the adsorption process. The adsorption is only slightly affected by the temperature.
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| 2. |
- Laine, J, et al.
(författare)
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Surface characterization of unbleached kraft pulps by means of ESCA
- 1994
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Ingår i: Cellulose. - 0969-0239 .- 1572-882X. ; 1, s. 145-160
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Tidskriftsartikel (refereegranskat)abstract
- The effect of digestion conditions (amount of effective alkali, digestion time) on the surface compositions of unbleached softwood (Pinus sylvestris) kraft pulp has been investigated by ESCA analysis. The quantities monitored were the angular dependence of the total O/C ratio, the relative amounts of carbons in different states of oxidation and the adsorption of Al and Ca ions to the carboxyl groups in the surface. Analysis of the angular dependence of ESCA intensities shows that the concentration of alkyl carbon is high in a very thin surface layer. This enrichment becomes more marked as the lignin content (kappa number) decreases, but it is not affected by extraction of the fibres with dichloromethane. It is concluded that the observed distribution is due to re-precipitation of lignin. In pulp that has not been extracted, there is also strong enrichment of extractives in the surface. This amount increases with increasing effective alkali but is relatively independent of the time of digestion. ESCA analysis of the Al and Ca bound to the carboxyl groups shows that the amount of these depends on digestion time; the results are consistent with the notion that the reprecipitated lignin contains carboxyl groups.
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| 3. |
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| 4. |
- Ström, G, et al.
(författare)
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Kinetics of steady-state wetting
- 1990
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Ingår i: Journal of Colloid and Interface Science. - 0021-9797 .- 1095-7103. ; 134, s. 107-116
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Ström, G, et al.
(författare)
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Surface chemical aspects of the behavior of soaps in pulp washing
- 1990
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 5, s. 44-51
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Tidskriftsartikel (refereegranskat)abstract
- In a kraft pulp washing line the wood resin consists of fatty acid and rosin acid soaps and a variety of neutral components. The removal of this material in the washing line is highly dependent on soap solubility, micelle formation, solubilization and the colloidal stability of precipitated resin particles. This papers summarizes several studies of the colloidal behavior of resin in model systems consisting of sodium abietate, sodium oleate and a model mixture of neutral components, and presents new data on micellization and solubilization. The highest solubility of the soaps and maximum solubilization of neutral compounds occurs at moderate ionic strength in mixed oleate/abietate solutions (1:2-2:1 by weight). Micelle formation is promoted by low temperature and moderate ionic strength; the solubilizing capacity of the micelles increases with temperature. Colloidal particles formed by precipitated resin are stabilized by kraft lignin. The model results are compared with an analysis of the distribution of resin in a pulp washing line. This distribution can be clearly understood from the results of the model study.
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| 6. |
- Ström, P., et al.
(författare)
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Adult human osteoblast-like cells do not express insulin-like growthfactor-I
- 1994
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 199:1, s. 78-82
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies using cultures of fetal rodents calvaria have indicated an important role for insulin-like growth factor-I (IGF-I) in the local control of bone formation. In this study, we have examined the expression of IGF-I in adult human osteoblast-like (hOB) cells. To detect very low levels and to distinguish between the two IGF-I mRNA transcripts Ea and Eb, which are formed by alternate splicing, we have used the reverse transcriptase-polymerase chain reaction (RT-PCR). Expression of both Ea and Eb IGF-I mRNA transcripts were found in human liver and in placenta. However, neither Ea nor Eb IGF-I mRNA could be detected under basal conditions or after stimulation with growth hormone in normal hOB cells and two human osteosarcoma cell lines with osteoblastic properties, SaOS-2 and MG-63. We conclude that adult hOB cells do not synthesize IGF-I. Thus, in contrast to its crucial role as a local regulator of skeletal remodeling in fetal rodent bone, IGF-I does not appear to have this autocrine function in adult human bone.
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