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- Fält, Susanna, et al.
(författare)
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Model films of cellulose II - improved preparation method and characterization of the cellulose film
- 2004
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Ingår i: Cellulose. - 0969-0239 .- 1572-882X. ; 11:2, s. 151-162
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Tidskriftsartikel (refereegranskat)abstract
- An optimization study of the preparation of spin-coated cellulose model films from the NMMO/DMSO system on silicon wafers has been made. The study shows that the cellulose concentration in the solution determines the cellulose film thickness and that the temperature of the solution affects the surface roughness. A lower solution temperature results in a lower surface roughness at cellulose concentrations below 0.8%. Using the described method, it is possible to prepare films with thicknesses of 30-90 nm with a constant surface roughness by changing the cellulose concentration, i.e. by dilution with DMSO. On these films, water has a contact angle less than 20degrees and about 50% of the material can, according to CP/MAS C-13-NMR spectroscopy on corresponding fibrous material, be considered to consist of crystalline cellulose II type material. It has further been shown that AFM can be used to determine the thickness of cellulose films, in both dry and wet states. In this method, the difference in height between the top surface and the underlying wafer has been measured at an incision made into the cellulose film. The cellulose films have also been spin-coated with the same technique as on the silicon oxide wafer onto the crystal in a quartz crystal microbalance (QCM). These model films were found to be suitable for swelling measurements with the QCM. The films were very stable during this type of measurement and films with different amounts of charges gave different swelling responses depending on their charges. As expected, films with a higher charge showed a higher swelling.
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| 2. |
- Hajdu, Susanna, et al.
(författare)
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Östersjöns blågrönalger : Viktiga kvävekällor
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Blågrönalger, eller cyanobakterier som de egentligenheter, har en unik förmåga att omvandla luftens kvävgastill mer användbar form. Genom denna process tillför dekväve i form av näring, både till sig själva och till restenav ekosystemet. Denna förmåga är förstås otroligt viktig,men ställer också till problem i våra redan övergöddavatten. Därför försöker man nu genom intensiva studierta reda på mer om hur blågrönalger fungerar och hurmycket kväve som tillförs av dessa organismer.
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| 6. |
- Ingri, Johan, et al.
(författare)
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Size distribution of colloidal trace metals and organic carbon during a coastal bloom in the Baltic Sea
- 2004
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203 .- 1872-7581. ; 91:1-4, s. 117-130
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Tidskriftsartikel (refereegranskat)abstract
- The physico-chemical speciation of organic carbon and selected metals was measured during a coastal bloom in Ekhagen Bay, Baltic Sea, using ultrafiltration.One important objective with the study was to see if any depletion of trace metals could be measured in the directly bioavailable fraction (<1000 Da, the soluble low molecular weight fraction, LMW) during a plankton bloom. Filters with five different cut-offs were used (1 kD (1000 Da), 5 kD, 10 kD, 100 kD and 0.22 μm) in order to delineate the size distribution of colloidal organic carbon (COC) and trace metals. During the bloom in May, LMW Al, Co, Cu, Mn and Ni concentrations decreased although the colloidal and particulate concentrations were relatively high. Data show that desorption of colloidal and particulate bound trace metals to the LMW fraction was slower than the process depleting the LMW fraction. Estimates of the maximum active uptake of Cu, Ni and Mn by the phytoplankton, and the loss of non-bioactive Al from the LMW fraction, indicate that processes other than active uptake by phytoplankton must contribute to the observed depletion of trace metals in the LMW fraction. Hence, in order to estimate the bioavailable pool of trace metals for plankton during bloom conditions, these other processes must be understood and quantified. Transparent Exopolymeric Particles (TEP, reflecting sugar-rich phytoplankton exudates) increased around eight times during the plankton bloom. We hypothesize that the formation of TEP is a process that might be important for the transfer of trace metals from the LMW to the particulate fraction during the phytoplankton bloom, but the significance of TEP for this depletion in Baltic Sea surface water remains to be shown.
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| 7. |
- Larsson, Susanna C, et al.
(författare)
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Dietary long-chain n-3 fatty acids for the prevention of cancer : a review of potential mechanisms
- 2004
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Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 79:6, s. 935-45
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Tidskriftsartikel (refereegranskat)abstract
- Increasing evidence from animal and in vitro studies indicates that n-3 fatty acids, especially the long-chain polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid, present in fatty fish and fish oils inhibit carcinogenesis. The epidemiologic data on the association between fish consumption, as a surrogate marker for n-3 fatty acid intake, and cancer risk are, however, somewhat less consistent. This review highlights current knowledge of the potential mechanisms of the anticarcinogenic actions of n-3 fatty acids. Moreover, a possible explanation of why some epidemiologic studies failed to find an association between n-3 fatty acid intake and cancer risk is provided. Several molecular mechanisms whereby n-3 fatty acids may modify the carcinogenic process have been proposed. These include suppression of arachidonic acid-derived eicosanoid biosynthesis; influences on transcription factor activity, gene expression, and signal transduction pathways; alteration of estrogen metabolism; increased or decreased production of free radicals and reactive oxygen species; and mechanisms involving insulin sensitivity and membrane fluidity. Further studies are needed to evaluate and verify these mechanisms in humans to gain more understanding of the effects of n-3 fatty acid intake on cancer risk.
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| 8. |
- Larsson, Susanna C., et al.
(författare)
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Fruit and vegetable consumption in relation to ovarian cancer incidence : the Swedish Mammography Cohort
- 2004
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 90:11, s. 2167-70
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Tidskriftsartikel (refereegranskat)abstract
- We prospectively examined the incidence of epithelial ovarian cancer and its subtypes in relation to baseline fruit and vegetable consumption in the Swedish Mammography Cohort, a population-based cohort study of 61 084 women aged 38-76 years in 1987-1990. During an average follow-up of 13.5 years, 266 incident cases of invasive epithelial ovarian cancer were diagnosed. After adjustment for potential confounders, we observed a statistically significant inverse association between consumption of vegetables and ovarian cancer risk (P-value for trend=0.01); the multivariate rate ratio (RR) for the comparison of three or more servings of vegetables per day with one or fewer servings per day was 0.61 (95% confidence interval (CI), 0.38-0.97). For fruit consumption a modest, not statistically significant, positive association was found (P-value for trend=0.07); the multivariate RR for the highest compared with the lowest category of consumption being 1.37 (95% CI, 0.90-2.06). The associations with fruit and vegetable consumption did not vary by subtype of ovarian cancer. These findings suggest that high consumption of vegetables, but not of fruits, may reduce the risk of ovarian cancer.
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| 10. |
- Larsson, Susanna C, et al.
(författare)
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Wine consumption and epithelial ovarian cancer
- 2004
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Ingår i: Cancer Epidemiology, Biomarkers and Prevention. - 1055-9965 .- 1538-7755. ; 13:11 Pt 1, s. 1823; author reply 1823-4
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Tidskriftsartikel (refereegranskat)
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