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| 2. |
- Adolfsson-Erici, Margaretha, et al.
(författare)
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Undersökning av det syntetiska sötningsmedlet sukralos med avseende på eventuella ekotoxikologiska effekter
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Två släkten av kräftdjur: Nitocra spinipes och Gammarus oceanicus resp zaddachiexponerades för sukralos i ekotoxikologiskt relevanta koncentrationer i kroniska tester. Viarbetade utifrån följande hypoteser: skalömsning hos kräftdjur störs av höga halter sukralos iomgivande vatten samt att sukralos inte biokoncentreras i exponerade organismer.Långtidsexponering resulterade i högre dödlighet hos juvenila gammarider. Sukralos syntesinte påverka skalömsningstiden för de adulta honorna i ett pre-copula experiment. Inga teckenpå biokoncentrering kunde märkas. Exponeringen av Nitocra resulterade i att de djur somexponerats för de lägre koncentrationerna av sukralos var längre jämfört med kontrolldjurenmedan för individer exponerade för de högre koncentrationerna minskade längden medökande sukraloskoncentration. De kortaste individerna återfanns i den positiva kontrollen ochhade exponerats för 50 μg/L lindan. RNA-innehållet varierade mellan exponeringarna och denvar lägst i 500μg/L och högst i 5000 μg/L exponeringen Vi fann däremot inget signifikantsamband mellan RNA-innehåll och tillväxthastighet hos Nitocra. Detta kan möjligen vara eneffekt av sukralosexponering, eftersom linjära responser från tidigare experiment har noterats.Inga skillnader avseende medelutvecklingstiden var signifikanta. Renat avloppsvatten frånHenriksalsverken innehöll relativt höga koncentrationer sukralos liksom ytvatten från trereningsverksrecipienter.
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| 3. |
- Arvedson, Mats, et al.
(författare)
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Packet or Circuit Switched Voice Radio Bearers-A Capacity Evaluation for GERAN
- 2002
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Konferensbidrag (refereegranskat)abstract
- GERAN, including the EDGE radio interface, con-stitutes the 3G evolution of GSM. The use of packet switched voice radio bearers has been discussed in the GERAN standardization, but has as yet not been adopted. This paper presents a thorough capacity comparison of circuit and packet switched voice bearers, applied to GERAN. Thus the standardization decision is verified, but also a framework for future similar investigations is provided. Several parameters affect the relative performance of circuit and packet switching. This report evaluates the effect of four of these parameters, expected to have major impact on the relative performance: reuse factor, resource pool size, voice activity, and additional overhead in the packet switched case. Varying the above parameters, it is seen that in certain blocking-limited scenarios packet switching may increase capacity significantly. The highest overall capacity is however achieved in inter-ference-limited scenarios, for which packet switching provides no capacity gain.
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| 4. |
- Arvidson, Magnus, et al.
(författare)
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Brandskydd på Bo01
- 2001
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Ingår i: Bygg och Teknik. - 0281-658X .- 2002-8350. ; 93:6, s. 12-16
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 5. |
- Bergström, Lars Magnus, et al.
(författare)
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A model-independent evaluation of experimental data, and comparison with theory, of synergistic effects in mixtures of an ionic and a nonionic surfactant
- 2003
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 19:26, s. 10719-10725
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Tidskriftsartikel (refereegranskat)abstract
- Critical micelle concentrations for mixtures of an anionic (sodium dodecyl sulfate) and a nonionic (decyl beta-glucoside) surfactant was obtained from surface tension measurements at different concentrations of added NaCl. The observed synergistic effects were analyzed by means of introducing a novel model-independent synergy parameter. The model-independent evaluation has enabled the comparison of experimental results with a theoretical model based on the Poisson-Boltzmann (PB) mean field theory for spherical, cylindrical, and planar geometries, respectively. We found that best agreement with experimental data was obtained for largely curved structures (spherical and cylindrical micelles) at all [NaCl], which is consistent with the fact that rather small micelles, as a rule, form at the critical micelle concentration. Moreover, the PB theory was found to better describe synergistic behavior of the experimental data than the more conventional regular mixture theory, in particular at low electrolyte concentrations. The magnitude of the observed synergistic effects was found to increase as a small amount of NaCl was added and reach a maximum at [NaCl] = 10 mM, in agreement with the PB theory. As expected, synergism was observed to decrease in magnitude upon further addition of NaCl.
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| 6. |
- Bergström, Lars Magnus, et al.
(författare)
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A theoretical analysis of synergistic effects in mixed surfactant systems
- 2000
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 16:18, s. 7173-7181
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Tidskriftsartikel (refereegranskat)abstract
- Synergistic effects in mixed binary surfactant systems have been investigated by analyzing the main contributions to the free energy of forming a mixed surfactant aggregate. We show that a nonlinear behavior of the critical micelle concentration (cmc) with respect to the surfactant composition of the aggregates is determined by a nonlinear behavior of the free energy per aggregated surfactant. It appears that synergistic effects are due mainly to entropic free energy contributions related with the surfactant headgroups. For a mixture of a monovalent ionic and a nonionic surfactant in the absence of added salt we obtain, entirely because of electrostatic reasons, a negative deviation from ideal behavior of the cmc vs the aggregate composition corresponding to an interaction parameter beta approximate to -1, whereas beta values on the order of -5 or even less can arise for mixtures of two ionic surfactants with the same charge number but with different hydrocarbon moieties. Moreover, we introduce a novel expression for the free energy of mixing aggregated surfactant headgroups with surrounding solvent molecules. Accordingly, synergistic effects arise as a result of different headgroup cross-section areas in mixtures of two nonionic surfactants with rigid headgroups. These effects are found to be rather small, with 0 > beta > -1, when the difference in headgroup size is modest but can become more significant when the size difference is larger. In mixtures of an ionic and a nonionic surfactant with different headgroup cross-section areas the two contributions to synergistic effects always enhance one another and, hence, beta values below -1 are obtained. Generally, the synergistic effects tend to increase with increasing asymmetry between the two surfactants.
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| 7. |
- Bergström, Lars Magnus, et al.
(författare)
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Synergistic effects in binary surfactant mixtures
- 2004
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Ingår i: Progress in Colloid and Polymer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0340-255X .- 1437-8027. ; 123, s. 16-22
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Tidskriftsartikel (refereegranskat)abstract
- By considering the main contributions to the micellar free energy we have analysed the synergistic effect often seen on the CMC of a binary surfactant mixture. The synergistic effects are due mainly to the entropic free energy contributions related with the surfactant head groups. Several cases have been treated: (i) For a mixture of a monovalent ionic and a non-ionic surfactant in the absence of added salt we obtain, entirely because of electrostatic reasons, a negative deviation from the ideal behaviour corresponding to an interaction parameter β≈-1. Upon adding an inert salt we found that the magnitude of the synergistic effect first increases, reaches a maximum and eventually decreases. (ii) For mixtures of two ionic surfactants with the same charge number but with different hydrocarbon moieties β-values as low as -10 may arise. (iii) For mixtures of an anionic and a cationic surfactant enormous effects are anticipated yielding β≤-20 depending on the CMCs of respective pure surfactant. (iv) Synergistic effects due to different cross-section areas of the head groups are found to be rather small, with 0 > β > -1, provided the difference in head group size is modest but can become more significant when the size difference is larger.
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| 8. |
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| 9. |
- Bohm, Christian, et al.
(författare)
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ATLAS TileCal Digitizer Test System and Quality Control
- 2004
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Ingår i: CERN Note: ATL-TILECAL-2004-009.
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Tidskriftsartikel (refereegranskat)abstract
- This document describes the tests of the quality control procedure for the ATLAS TileCal digitizer unit. Since the ATLAS detector will fill most of the space in the detector cavity it will be difficult to disassemble parts of the detector. Therefore quality control is extremely important for every part of ATLAS. In Stockholm the digitizer units are tested in a testbench to ensure functionality and reliability in the ATLAS environment. The document includes a brief description of the ATLAS TileCal digitizer system and a description of the testbench setup. It also includes a description of the tests preformed and of the quality control procedure developed in Stockholm together with a production status.
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| 10. |
- Bylund, Nicklas, et al.
(författare)
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Simulation driven car body development using property based models
- 2001
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Ingår i: Proceedings of the IBEC 2001, International Body Engineering Conference and Exhibition. - Detroit : Society of Automotive Engineers, Incorporated. - 768008328
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Konferensbidrag (refereegranskat)abstract
- A method for the development of car bodies, from conceptual to detailed design, is presented. The conceptual design is broken down to a numerical property- based model (PBM) representing the mechanical behavior of the concept. In the PBM, the local properties are balanced to fulfill the global stiffness requirements. The main topology is defined and the structural components, i.e., joints, beams and sheets are connected in predefined nodes and represented in a finite element (FE) model as super elements, beam elements and thin shell elements. In the realization of the car structure, the performance of the PBM components are used as requirements in the detailed design. Different technologies, materials and manufacturing processes can be considered as long as the properties of the component agree with the ones stated by the PBM. The detailed design of each component is made by design engineers, supported by single purpose tools. The design engineers iterate the design until only a small difference between target and component performance exists
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