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- Lützenkirchena, J., et al.
(författare)
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Protonation of different goethite surfaces—Unified models for NaNO3 and NaCl media
- 2008
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 317:1, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- Acid–base titration data for two goethites samples in sodium nitrate and sodium chloride media are discussed. The data are modeled based on various surface complexation models in the framework of the multi site complexation (MUSIC) model. Various assumptions with respect to the goethite morphology are considered in determining the site density of the surface functional groups. The results from the various model applications are not statistically significant in terms of goodness of fit. More importantly, various published assumptions with respect to the goethite morphology (i.e., the contributions of different crystal planes and their repercussions on the “overall” site densities of the various surface functional groups) do not significantly affect the final model parameters within simple 1-pK approximations. The simultaneous fit of the chloride and nitrate data results in electrolyte binding constants, which are applicable over a wide range of electrolyte concentrations including mixtures of chloride and nitrate. Model parameters for the goethite sample with 90 m2/g specific surface area are in excellent agreement with parameters that were independently obtained by another group on different goethite titration data sets.
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| 4. |
- Lövgren, Ingemar, 1972, et al.
(författare)
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The WST method, a fracture mechanics test method for FRC
- 2008
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Ingår i: Materials and Structures/Materiaux et Constructions. - : Springer Science and Business Media LLC. - 1359-5997. ; 41:1, s. 197-211
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Tidskriftsartikel (refereegranskat)abstract
- The applicability of the wedge-splitting test method (WST), for determining fracture properties of fibre-reinforced concrete, is discussed. Experimental results, using the WST method, are compared with results from uniaxial tension tests (UTT) and three-point bending tests (3PBT) for five different FRC compositions. Furthermore, for the WST method, two different specimen sizes have been investigated. Results from this investigation demonstrate the applicability of the WST method and show that the scatter of the test results is lower than for the 3PBT. Through inverse analysis, stress-crack opening (sigma-w) relationships have been determined for each mix and test method. For the two WST specimen sizes, there is no apparent difference either in the number of fibres (per cm(2)) crossing the fracture plane or in the fracture properties. The major factor contributing to the scatter in the test results is believed to be related to the variation in the number of fibres across the fracture plane. Furthermore, the inverse analyses indicate no systematic differences in the determined parameters between two WST specimens or between the WST and the 3PBT.
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| 5. |
- Nord, Stefan, 1980-, et al.
(författare)
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The RimP protein is important for maturation of the 30S ribosomal subunit
- 2009
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 386:3, s. 742-753
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Tidskriftsartikel (refereegranskat)abstract
- The in vivo assembly of ribosomal subunits requires assistance by auxiliary proteins that are not part of mature ribosomes. More such assembly proteins have been identified for the assembly of the 50S than for the 30S ribosomal subunit. Here, we show that the RimP protein (formerly YhbC or P15a) is important for the maturation of the 30S subunit. A rimP deletion (DeltarimP135) mutant in Escherichia coli showed a temperature-sensitive growth phenotype as demonstrated by a 1.2-, 1.5-, and 2.5-fold lower growth rate at 30, 37, and 44 degrees C, respectively, compared to a wild-type strain. The mutant had a reduced amount of 70S ribosomes engaged in translation and showed a corresponding increase in the amount of free ribosomal subunits. In addition, the mutant showed a lower ratio of free 30S to 50S subunits as well as an accumulation of immature 16S rRNA compared to a wild-type strain, indicating a deficiency in the maturation of the 30S subunit. All of these effects were more pronounced at higher temperatures. RimP was found to be associated with free 30S subunits but not with free 50S subunits or with 70S ribosomes. The slow growth of the rimP deletion mutant was not suppressed by increased expression of any other known 30S maturation factor.
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