| 1. |
- Beal, Jacob, et al.
(författare)
-
Robust estimation of bacterial cell count from optical density
- 2020
-
Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
-
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.
|
|
| 2. |
- Heinälä, Milla, et al.
(författare)
-
Survey on methodologies in the risk assessment of chemical exposures in emergency response situations in Europe
- 2013
-
Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 244, s. 545-554
-
Tidskriftsartikel (refereegranskat)abstract
- A scientifically sound assessment of the risk to human health resulting from acute chemical releases is the cornerstone for chemical incident prevention, preparedness and response. Although the general methodology to identify acute toxicity of chemicals has not substantially changed in the last decades, there is ongoing debate on the current approaches for human health risk assessment in scenarios involving acute chemical releases.A survey was conducted to identify 1) the most important present and potential future chemical incident scenarios and anticipated changes in chemical incidents or their management; 2) information, tools and guidance used in different countries to assess health risks from acute chemical releases; and 3) needs for new information, tools, guidance and expertise to enable the valid and rapid health risk assessment of acute chemical exposures.According to the results, there is an obvious variability in risk assessment practices within Europe. The multiplicity of acute exposure reference values appears to result in variable practices. There is a need for training especially on the practical application of acute exposure reference values. Although acutely toxic and irritating/corrosive chemicals will remain serious risks also in future the development of plausible scenarios for potential emerging risks is also needed. This includes risks from new mixtures and chemicals (e.g. nanoparticles).
|
|
| 3. |
- Schrenk, Dieter, et al.
(författare)
-
Risk to human health related to the presence of perfluoroalkyl substances in food.
- 2020
-
Ingår i: EFSA journal. European Food Safety Authority. - : Wiley. - 1831-4732. ; 18:9
-
Tidskriftsartikel (refereegranskat)abstract
- The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluoroalkyl substances (PFASs) in food. Based on several similar effects in animals, toxicokinetics and observed concentrations in human blood, the CONTAM Paneldecided to perform the assessment for the sum of four PFASs: PFOA, PFNA, PFHxS and PFOS. These made up half of the lower bound (LB) exposure to those PFASs with available occurrence data, the remaining contribution being primarily from PFASs with short half-lives. Equal potencies were assumed for the four PFASs included in the assessment. The mean LB exposure in adolescents and adult age groups ranged from 3 to 22, the 95th percentile from 9 to 70 ng/kg body weight (bw) per week. Toddlers and 'other children' showed a twofold higher exposure. Upper bound exposure was 4- to 49-fold higher than LB levels, but the latter were considered more reliable. 'Fish meat', 'Fruit and fruit products' and 'Eggs and egg products' contributed most to the exposure. Based on available studies in animals and humans, effects on the immune system were considered the most critical for the risk assessment. From a human study, a lowest BMDL 10 of 17.5 ng/mL for the sum of the four PFASs in serum was identified for 1-year-old children. Using PBPK modelling, this serum level of 17.5 ng/mL in children was estimated to correspond to long-term maternal exposure of 0.63 ng/kg bw per day. Since accumulation over time is important, a tolerable weekly intake (TWI) of 4.4 ng/kg bw per week was established. This TWI also protects against other potential adverse effects observed in humans. Based on the estimated LB exposure, but also reported serum levels, the CONTAM Panelconcluded that parts of the European population exceed this TWI, which is of concern.
|
|
| 4. |
- Tumanov, Nikolay A., et al.
(författare)
-
High-Pressure Study of Mn(BH4)(2) Reveals a Stable Polymorph with High Hydrogen Density
- 2016
-
Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 28:1, s. 274-283
-
Tidskriftsartikel (refereegranskat)abstract
- High-pressure behavior of alpha-Mn(BH4)(2) was studied up to 29.4 GPa in diamond anvil cells using powder Xray diffraction combined with DFT calculations and Raman spectroscopy, and two new polymorphs were discovered. The first polymorph, delta-Mn(BH4)(2), forms near 1 GPa and is isostructural to the magnesium analogue delta-Mg(BH4)(2). This polymorph is stable upon decompression to ambient conditions and can also be obtained by compression of alpha-Mn(BH4)(2) in a large-volume steel press as well as by high-energy ball milling. It shows a high volumetric density of hydrogen of 125 g H-2/L at ambient conditions. delta-Mn(BH4)(2) was refined in the space group I4(1)/acd with the cell parameters a = 7.85245(6), c = 12.1456(2) angstrom, and V = 748.91(1) angstrom(3) at ambient conditions; it can also be described in a stable P-4n2 superstructure. Its thermal stability was studied by in situ X-ray powder diffraction and thermal analysis coupled with mass-spectroscopy. delta-Mn(BH4)(2) transforms back to alpha-Mn(BH4)(2) upon heating in the temperature range of 67-109 degrees C in Ar (1 bar) or H-2 (100 bar) atmosphere, and a decomposition is initiated at 130 degrees C with the release of hydrogen and some diborane. Mn(BH4)(2) undergoes a second phase transition to delta'-Mn(BH4)(2) in the pressure range of 8.6-11.8 GPa. delta'-phase is not isostructural to the second high-pressure phase of Mg(BH4)(2), and its structure was determined in the root 2a X c supercell compared to the delta-phase and refined in the space group Fddd with a = 9.205(17), b = 9.321(10), c = 12.638(15) angstrom, and V = 1084(3) angstrom(3) at 11.8 GPa. Equations of state were determined for alpha- and delta-Mn(BH4)(2).
|
|
| 5. |
- Ågerstrand, Marlene, et al.
(författare)
-
A call for action : Improve reporting of research studies to increase the scientific basis for regulatory decision-making
- 2018
-
Ingår i: Journal of Applied Toxicology. - : Wiley. - 0260-437X .- 1099-1263. ; 38:5, s. 783-785
-
Tidskriftsartikel (refereegranskat)abstract
- This is a call for action to scientific journals to introduce reporting requirements for toxicity and ecotoxicity studies. Such reporting requirements will support the use of peer-reviewed research studies in regulatory decision-making. Moreover, this could improve the reliability and reproducibility of published studies in general and make better use of the resources spent in research.
|
|
