| 11. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 12. |
- Gislason, S.R., et al.
(författare)
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Environmental pressure from the 2014–15 eruption of Bárðarbunga volcano, Iceland
- 2015
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Ingår i: Geochemical Perspectives Letters. - : European Association of Geochemistry. - 2410-3403 .- 2410-339X. ; 1:2015, s. 84 - 93
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Tidskriftsartikel (refereegranskat)abstract
- The effusive six months long 2014-2015 Bárðarbunga eruption (31 August-27 February) was the largest in Iceland for more than 200 years, producing 1.6 ± 0.3 km3 of lava. The total SO2 emission was 11 ± 5 Mt, more than the amount emitted from Europe in 2011. The ground level concentration of SO2 exceeded the 350 μg m−3 hourly average health limit over much of Iceland for days to weeks. Anomalously high SO2 concentrations were also measured at several locations in Europe in September. The lowest pH of fresh snowmelt at the eruption site was 3.3, and 3.2 in precipitation 105 km away from the source. Elevated dissolved H2SO4, HCl, HF, and metal concentrations were measured in snow and precipitation. Environmental pressures from the eruption and impacts on populated areas were reduced by its remoteness, timing, and the weather. The anticipated primary environmental pressure is on the surfacewaters, soils, and vegetation of Iceland.
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| 13. |
- Hansen, Lea B.S., et al.
(författare)
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A low-gluten diet induces changes in the intestinal microbiome of healthy Danish adults
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- © 2018, The Author(s). Adherence to a low-gluten diet has become increasingly common in parts of the general population. However, the effects of reducing gluten-rich food items including wheat, barley and rye cereals in healthy adults are unclear. Here, we undertook a randomised, controlled, cross-over trial involving 60 middle-aged Danish adults without known disorders with two 8-week interventions comparing a low-gluten diet (2 g gluten per day) and a high-gluten diet (18 g gluten per day), separated by a washout period of at least six weeks with habitual diet (12 g gluten per day). We find that, in comparison with a high-gluten diet, a low-gluten diet induces moderate changes in the intestinal microbiome, reduces fasting and postprandial hydrogen exhalation, and leads to improvements in self-reported bloating. These observations suggest that most of the effects of a low-gluten diet in non-coeliac adults may be driven by qualitative changes in dietary fibres.
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| 14. |
- Mach, H., et al.
(författare)
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New structure information on Mg-30, Mg-31 and Mg-32
- 2005
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25, s. 105-109
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Konferensbidrag (refereegranskat)abstract
- The fast timing beta gamma gamma(t) method was applied to investigate the level lifetimes in Mg-30,Mg-31,Mg-32. Levels in Mg have been populated in beta and beta-delayed neutron emission of Na, at the ISOLDE facility. From the gamma gamma coincidences a number of new states have been identified and new level schemes were constructed for 30 31,32 Mg. The following preliminary half lives have been determined: T-1/2 = 3.9(4) ns for the 1789 keV state in Mg-30, T-1/2 = 133(8) ps and 10.5(8) us for the 221 keV and 461 keV states in Mg-31, respectively, and T1/2 = 16(4) ps for the 885 keV level in 32Mg. The 1789 keV level was established as a candidate for the intruder 0(+) configuration in Mg-30 with a possible strong E0 branch to the ground state.
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| 15. |
- Krawczyk-Barsch, E., et al.
(författare)
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Immobilization of uranium in biofilm microorganisms exposed to groundwater seeps over granitic rock tunnel walls in Olkiluoto, Finland
- 2012
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Ingår i: Geochimica Et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 0046-564X. ; 96, s. 94-104
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Tidskriftsartikel (refereegranskat)abstract
- In an underground rock characterization facility, the ONKALO tunnel in Finland, massive 5-10-mm thick biofilms were observed attached to tunnel walls where groundwater was seeping from bedrock fractures at a depth of 70 m. In laboratory experiments performed in a flow cell with detached biofilms to study the effect of uranium on the biofilm, uranium was added to the circulating groundwater (CGW) obtained from the fracture feeding the biofilm. The final uranium concentration in the CGW was adjusted to 4.25 x 10(-5) M, in the range expected from a leaking spent nuclear fuel (SNF) canister in a future underground repository. The effects were investigated using microelectrodes to measure pH and E-h, time-resolved laser fluorescence spectroscopy (TRLFS), energy-filtered transmission electron microscopy (EF-TEM), and electron energy-loss spectroscopy (EELS) studies and thermodynamic calculations were utilized as well. The results indicated that the studied biofilms constituted their own microenvironments, which differed significantly from that of the CGW. A pH of 5.37 was recorded inside the biofilm, approximately 3.5 units lower than the pH observed in the CGW, due to sulfide oxidation to sulfuric acid in the biofilm. Similarly, the E-h of +73 mV inside the biofilm was approximately 420 mV lower than the E-h measured in the CGW. Adding uranium increased the pH in the biofilm to 7.27 and reduced the E-h to -164 mV. The changes of E-h and pH influenced the bioavailability of uranium, since microbial metabolic processes are sensitive to metals and their speciation. EF-TEM investigations indicated that uranium in the biofilm was immobilized intracellularly in microorganisms by the formation of metabolically mediated uranyl phosphate, similar to needle-shaped autunite (Ca[UO2](2)[PO4](2)center dot 2-6H(2)O) or meta-autunite (Ca[UO2](2)[PO4](2)center dot 10-12H(2)O). In contrast, TRLFS studies of the contaminated CGW identified aqueous uranium carbonate species, likely (Ca2UO2[CO3](3)), formed due to the high concentration of carbonate in the CGW. The results agreed with thermodynamic calculations of the theoretically predominant field of uranium species, formed in the uranium-contaminated CGW at the measured geochemical parameters. This investigation clearly demonstrated that biological systems must be considered as a part of natural systems that can significantly influence radionuclide behavior. The results improve our understanding of the mechanisms of biofilm response to radionuclides in relation to safety assessments of SNF repositories. (C) 2012 Elsevier Ltd. All rights reserved.
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| 16. |
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| 17. |
- Vendelbo Lind, Mads, 1988, et al.
(författare)
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Plasma Alkylresorcinols Reflect Gluten Intake and Distinguish between Gluten-Rich and Gluten-Poor Diets in a Population at Risk of Metabolic Syndrome
- 2016
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Ingår i: Journal of Nutrition. - : Elsevier BV. - 1541-6100 .- 0022-3166. ; 146:10, s. 1991-1998
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Tidskriftsartikel (refereegranskat)abstract
- Background: Many patients with celiac disease experience difficulties in adherence to a gluten-free diet. Methods for testing compliance to a gluten-free diet are costly and cumbersome. Thus, a simple biomarker of gluten intake is needed in a clinical setting and will be useful for epidemiologic studies investigating wider effects of gluten intake. Objective: The aim was to evaluate plasma total alkylresorcinol concentrations as a measure of gluten intake. Methods: In this randomized, controlled, crossover intervention study in 52 Danish adults with features of the metabolic syndrome, we compared 8 wk of a gluten-rich and gluten-poor diet separated by a washout period of wk. We measured fasting plasma concentrations of alkylresorcinols to determine if they reflected differences in gluten intake as a secondary outcome of the original study. In addition, we investigated in 118 Danish adults the cross-sectional association between self reported gluten intake and plasma alkylresorcinols in the same and a similar study at baseline. We used mixed-model ANCOVA for examining treatment effects, a classification tree to determine compliance to the gluten-poor diet, and linear regression models for examining baseline correlation between plasma alkylresorcinol concentrations and gluten intake. Results: Plasma total alkylresorcinols decreased more during the gluten-poor period (geometric mean: -124.8 nmol/L; 95% CI: -156.5, -93.0 nmol/L) than in the gluten-rich period (geometric mean: -31.8 nmol/L; 95% CI: -63.1, -0.4 nmol/L) (P
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| 18. |
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