| 1. |
- Andersson, Anna, et al.
(författare)
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Evaluation and characterization of ammoniumpolyphosphate-pentaerythritol-based systems for intumescent coatings
- 2007
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 104:2, s. 748-753
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Tidskriftsartikel (refereegranskat)abstract
- Intumescent coatings are increasingly used as a method of passive fire protection on steel constructions. By forming a carbon network and releasing a blowing agent, the thin intumescent film swells 100-fold at elevated temperatures. The highly insulating foam effectively prevents the load bearing steel from reaching its critical temperature at which it looses its mechanical properties and collapses. The role of the carbon donor in intumescent coatings has been studied. Comparison in temperature development, foaming ratios, and rheological behavior has been performed between formulations containing pentaerythritol (penta), di-penta, and tri-penta. A simulated fire test, in which the temperature development during intumescence was studied, showed that the formulations containing penta were considerably more efficient in keeping a low temperature throughout the process. A more rapid temperature development was displayed when using di-penta and tripenta as the carbon donor. Rheometer tests indicate that penta formulations enter the inturnescent process at a lower temperature and stays in it for a longer time than di-penta and tri-penta formulations. Furthermore, the crossover temperature and maximum phase angle are shifted towards higher temperatures by replacing penta with di-penta and with tri-penta in the formulations, respectively.
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| 2. |
- Andersson, Anna, et al.
(författare)
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Intumescent foams - A novel flame retardant system for flexible polyurethane foams
- 2008
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 109:4, s. 2269-2274
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Tidskriftsartikel (refereegranskat)abstract
- A combination of intumescent components was evaluated as a novel flame retardant system in a flexible polyurethane foam, and the incorporation of these components gave rise to a significant enhancement of the flame retardant properties of the foam. The heat release rate was lowered at an early stage as well as throughout the fire, the total heat production was decreased and the time to ignition was prolonged. Mechanical measurements of the foam revealed enhanced properties in terms of stiffness accompanied by a large decrease in elongation at break as compared with a reference foam. (c) 2008 Wiley Periodicals, Inc.
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| 3. |
- Andersson, Anna, et al.
(författare)
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Shear Behavior of Flexible Polyurethane Foams Under Uniaxial Compression
- 2009
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 111:5, s. 2290-2298
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms behind the load building capabilities of a hyperbranched polymer (HBP) in polyurethane (PU) foams have been investigated, using microscopy techniques and mechanical analyses. By broadening the traditional uniaxial compression characterization of PU foams to include combined shear deformations and compression behavior, an apparent Poisson ratio of the foam could be obtained in situ. The Poisson ratio as function of uniaxial compression ratio of the foam was thus studied for foams filled with Styrene Acrylonitrile (SAN) and foams containing HBP. Generally a window of deformation ratios could be defined in which the Poisson ratio was negative. The width of this window varied systematically with the SAN loading, where an increase in SAN particle loading resulted in a broadening of the negative Poisson ratio window. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2290-2298, 2009
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| 4. |
- Andersson, Anna, et al.
(författare)
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Vibration and Acoustic Damping of Flexible Polyurethane Foams Modified with a Hyperbranched Polymer
- 2010
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Ingår i: Journal of Cellular Plastics. - 0021-955X. ; 46:1, s. 73-93
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic mechanical properties and acoustic damping of polyurethane (PU) foams loaded with a hyperbranched polymer (HBP) have been studied. The results show a significant modulus enhancement parallel to an increased vibration damping in the low frequency range of approximate to 1 Hz with increased amount of HBP. Furthermore, an increased acoustic damping in the frequency interval of 500-1600 Hz is observed with increasing amount of HBP. The origin of these property enhancements are sought in the morphology and the chemical composition of the PU foam. It has been found that no visible differences in cell sizes and strut thicknesses exist among the foams. However, FTIR reveals significant differences in chemical composition between the foams of different HBP content, indicating increased crosslinking.
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| 5. |
- Andersson, Kent, 1967-, et al.
(författare)
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The Military Utility Assessment Method for Future Technologies
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this report is to describe the Swedish Defence University (SEDU) Military Utility Assessment Method for Future Technologies (MUAFT). The report describes the actions taken in each step of the process and ends with references and a template for the technology memos used as basis for assessment.
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| 6. |
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| 7. |
- Assarsson, Erika, et al.
(författare)
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Severe defect in thymic development in an insertional mutant mouse model.
- 2007
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Ingår i: Journal of immunology (Baltimore, Md. : 1950). - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 178:8, s. 5018-5027
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Tidskriftsartikel (refereegranskat)abstract
- Transgenic mice were generated expressing NK1.1, an NK cell-associated receptor, under control of the human CD2 promoter. Unexpectedly, one of the founder lines, Tg66, showed a marked defect in thymic development characterized by disorganized architecture and small size. Mapping of the transgene insertion by fluorescence in situ hybridization revealed integration in chromosome 2, band G. Already from postnatal day 3, the thymic architecture was disturbed with a preferential loss of cortical thymic epithelial cells, a feature that became more pronounced over time. Compared with wild-type mice, total thymic cell numbers decreased dramatically between 10 and 20 days of age. Thymocytes isolated from adult Tg66 mice were predominantly immature double-negative cells, indicating a block in thymic development at an early stage of differentiation. Consequently, Tg66 mice had reduced numbers of peripheral CD4(+) and CD8(+) T cells. Bone marrow from Tg66 mice readily reconstituted thymi of irradiated wild-type as well as RAG-deficient mice. This indicates that the primary defect in Tg66 mice resided in nonhemopoietic stromal cells of the thymus. The phenotype is observed in mice heterozygous for the insertion and does not resemble any known mutations affecting thymic development. Preliminary studies in mice homozygous for transgene insertion reveal a more accelerated and pronounced phenotype suggesting a semidominant effect. The Tg66 mice may serve as a useful model to identify genes regulating thymic epithelial cell differentiation, thymic development, and function.
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| 8. |
- Bornadel, Amin, et al.
(författare)
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Optimization of a two-step process comprising lipase catalysis and thermal cyclizationimproves the efficiency of synthesis of six-membered cyclic carbonate from trimethylolpropane and dimethylcarbonate.
- 2013
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Ingår i: Biotechnology Progress. - : Wiley. - 1520-6033 .- 8756-7938. ; 29:1, s. 66-73
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Tidskriftsartikel (refereegranskat)abstract
- Six-membered cyclic carbonates are potential monomers for phosgene and/or isocyanate free polycarbonates and polyurethanes via ring-opening polymerization. A two-step process for their synthesis comprising lipase-catalyzed transesterificationofa polyol, trimethylolpropane(TMP) with dimethylcarbonate(DMC)in a solvent-free system followed by thermal cyclization was optimized to improve process efficiency and selectivity. Using full factorial designed experiments and partial least squares (PLS) modeling for thereaction catalyzed by Novozym®435 (N435; immobilized Candida antarctica lipase B), the optimum conditions for obtaining either high proportion of mono-carbonated TMP and TMP-cyclic-carbonate (3 and 4), or di-carbonated TMP and monocarbonated TMP-cyclic-carbonate (5 and 6) were found. The PLS model predicted that the reactions using 15-20% (w/w) N435 at DMC:TMP molar ratio of 10-30 can reach about 65% total yield of 3 and 4 within 10 h, and 65-70% total yield of 5 and 6 within 32-37 h, respectively. High consistency between the predictedresults and empirical data was shown with 66.1% yield of 3 and 4 at 7 h and 67.4% yield of 5 and 6 at 35 h, using 18% (w/w) biocatalyst and DMC:TMPmolar ratio of20. Thermal cyclization of the product from 7 h reaction, at 110 °C in the presence of acetonitrile increased the overall yield of cyclic carbonate 4 from about 2% to more than 75%within 24 h.N435 was reused for 5 consecutive batches, 10 h each, to give 3+4 with a yield of about 65% in each run. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012.
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| 9. |
- Dahlberg, Stefan, 1975, et al.
(författare)
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How representative is a self-selected web-panel? The effect on representativeness of different sampling procedures and survey modes
- 2012
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Ingår i: The Annual Meeting of the American Association for Public Opinion Research, Orlando, May 2012.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper makes a systematic comparison between different sampling procedures and survey modes by making use of three different types of surveys. In all three surveys, identical questions and wordings are used. However, they are all three separate studies whereas the first study is based on a representative sample of approximately 3 000 Swedish citizens (based on the national census register). This study is carried out as a traditional postal survey by the Swedish SOM-institute. The second study is also based on a representative sample of approximately 3 000 Swedish citizens (recruited by telephone from the national census register), but in this case the survey is entirely carried out as a web-survey, distributed by e-mail. The third and final study is carried out as a web-survey as well but is instead based on a selfrecruited citizen panel of 10 000 Swedish citizens. All three surveys were carried out during October to December, 2011. In order to evaluate potential differences between varying sampling procedures and survey modes, we will a) compare the composition of respondents in terms of general SES-related background characteristics between the three surveys, both in terms of potential differences in levels and correlations, and b) analyze the differences in three sets of questions tapping, values, attitudes and behavior. By doing this we will be able to uncover how representative a large-sample self-recruited panel actually can become as well as what the usage of new technological media in surveys does to an initially representative sample in a technologically advanced country. Important questions that we will be able to answer concerns to what extent different sampling procedures and survey modes affect the representativeness of a sample? If potential differences varies between different types of survey questions, i.e. questions relating to values, attitudes and behavior etc.
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| 10. |
- Dishisha, Tarek, et al.
(författare)
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An economical biorefinery process for propionic acid production from glycerol and potato juice using high cell density fermentation.
- 2013
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 135, s. 504-512
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Tidskriftsartikel (refereegranskat)abstract
- An economically sustainable process was developed for propionic acid production by fermentation of glycerol using Propionibacterium acidipropionici and potato juice, a by-product of starch processing, as a nitrogen/vitamin source. The fermentation was done as high-cell-density sequential batches with cell recycle. Propionic acid production and glycerol consumption rates were dependent on initial biomass concentration, and reached a maximum of 1.42 and 2.30gL(-1)h(-1), respectively, from 50gL(-1) glycerol at initial cell density of 23.7g(CDW)L(-1). Halving the concentration of nitrogen/vitamin source resulted in reduction of acetic and succinic acids yields by ∼39% each. At glycerol concentrations of 85 and 120gL(-1), respectively, 43.8 and 50.8gL(-1) propionic acid were obtained at a rate of 0.88 and 0.29gL(-1)h(-1) and yield of 84 and 78mol%. Succinic acid was 13g% of propionic acid and could represent a potential co-product covering the cost of nitrogen/vitamin source.
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