| 1. |
- Andres, B., et al.
(författare)
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Experimental analysis of stone wool sandwich composites exposed to constant incident heat fluxes and simulated parametric fires
- 2017
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Ingår i: 15th International Conference and Exhibition on Fire and Materials 2017. - 9781510846746 ; 2, s. 503-516
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Konferensbidrag (refereegranskat)abstract
- An experimental analysis of the fire behavior of stone wool composites with stainless steel and gypsum plasterboard linings was performed. The focus was to characterize the micro-scale behavior of stone wool, and identify the main processes occurring in stone wool composites when exposed to heat. Thermogravimetric analysis was applied to two different wools with varying densities and binder content in air and nitrogen atmospheres at 5, 10, and 20 K/min. Results show a low percentage of mass loss that could be linked to the low fraction of organic binder contained in the wool. Intermediate-scale composite assemblies were tested using the Heat-Transfer Inducing Rate System (H-TRIS). Specimens were composed of stainless steel-stone wool, and gypsum plasterboard-stone wool. Tests were performed at (1) constant low incident heat flux (7 kW/m2), (2) constant high incident heat flux (60 kW/m2), and (3) simulated parametric incident heat exposure. The results of these tests help to identify the relevant phenomena that should be taken into account when modelling building assemblies with stone wool cores (i.e. pyrolysis and combustion of the binder, water transport through the cross-section, and burning of paper).
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| 2. |
- Andres, Blanca, et al.
(författare)
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Response of stone wool–insulated building barriers under severe heating exposures
- 2018
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Ingår i: Journal of Fire Sciences. - : SAGE Publications. - 0734-9041 .- 1530-8049. ; 36:4, s. 315-341
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Tidskriftsartikel (refereegranskat)abstract
- This article presents the experimental results of stone wool–layered sandwich constructions, with either steel or gypsum claddings, tested under four different heating exposures: 7 kW/m2 incident radiant heat flux exposure, 60 kW/m2 incident radiant heat flux exposure, parametric time–temperature curve exposure and ISO 834 standard time–temperature exposure. The test apparatus used were a movable radiant panel system, a mid-scale furnace (1.5 m3) and a large-scale furnace (15 m3). The results show that reduced-scale tests are capable of reproducing the heat transferred through the construction at large scale provided there is limited mechanical degradation. The results indicate that the availability of oxygen is fundamental to the fire behaviour of the sandwich composites tested. Reactions occurring in stone wool micro-scale testing, such as oxidative combustion of the binder or crystallisation of the fibres, have a limited effect on the temperature increase when wool is protected from air entrainment.
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| 3. |
- Hendrix, S. B., et al.
(författare)
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Alzheimer's Disease Composite Score: a Post-Hoc Analysis Using Data from the LipiDiDiet Trial in Prodromal Alzheimer's Disease
- 2019
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Ingår i: Jpad-Journal of Prevention of Alzheimers Disease. - : SERDI. - 2274-5807 .- 2426-0266. ; 6:4, s. 232-236
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Tidskriftsartikel (refereegranskat)abstract
- As research evolves in prodromal AD, the need to validate sufficiently sensitive outcome measures, e.g. the Alzheimer's Disease Composite Score (ADCOMS) is clear. In the LipiDiDiet randomized trial in prodromal AD, cognitive decline in the study population was much less than expected in the timeframe studied. While the primary composite endpoint was insufficiently sensitive to detect a difference in the modified intention to treat population, the per-protocol population showed less decline in the active than the control group, indicating better treatment effects with regular product intake. These results were further strengthened by significant benefits on secondary endpoints of cognition and function, and brain atrophy. The present post-hoc analysis investigated whether ADCOMS could detect a difference between groups in the LipiDiDiet population (138 active, 140 control). The estimated mean change in ADCOMS from baseline (standard error) was 0.085 (0.018) in the active and 0.133 (0.018) in the control group; estimated mean treatment difference -0.048 (95% confidence intervals -0.090, -0.007; p=0.023), or 36% less decline in the active group. This suggests ADCOMS identified the cognitive and functional benefits observed previously, confirming the sensitivity of this composite measure.
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| 4. |
- Larsson, Maria, 1975-, et al.
(författare)
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Occurrence and leachability of polycyclic aromatic compounds in contaminated soils : Chemical and bioanalytical characterization
- 2018
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 622-623, s. 1476-1484
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Tidskriftsartikel (refereegranskat)abstract
- An important concern regarding sites contaminated with polycyclic aromatic compounds (PACs) is the risk of groundwater contamination by release of the compounds from soils. The goal of this study was to investigate the occurrence and leachability of 77 PACs including polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic compounds (NSO-PACs) among total aryl hydrocarbon receptor (AhR) agonists in soils from historical contaminated sites. A novel approach combining chemical and bioanalytical methods in combination with characterization of leachability by use of a column leaching test was used. Similar profiles of relative concentrations of PACs were observed in all soils, with parent PAHs accounting for 71 to 90% of total concentrations in soils. Contribution of oxy-PAHs, alkyl-PAHs and N-PACs ranged from 2 to 9%, 3 to 9% and 1 to 14%, respectively. Although the contributions of groups of PACs were small, some compounds were found in similar or greater concentrations than parent PAHs. Leachable fractions of 77 PACs from soils were small and ranged from 0.002 to 0.54%. Polar PACs were shown to be more leachable than parent PAHs. The contribution of analyzed PACS to overall AhR-mediated activities in soils and leachates suggests presence of other AhR agonists in soils, and a potential risk. Only a small fraction of AhR agonists was available in soils, indicating an overestimation of the risk if only total initial concentrations in soils would be considered in risk assessment. The results of the study strongly support that focus on 16US EPA PAHs may result in inadequate assessment of risk and hazard of PACs in complex environmental samples.
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| 5. |
- Livkiss, Karlis, et al.
(författare)
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Numerical study of a fire-driven flow in a narrow cavity
- 2019
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Ingår i: Fire Safety Journal. - : Elsevier BV. - 0379-7112. ; 108
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Tidskriftsartikel (refereegranskat)abstract
- Air cavities and gaps between material layers are common in construction systems, e.g. ventilated façades. Air cavity may provide a pathway for smoke and flame spread in case of fire. Performing physical testing to investigate different systems and fire scenarios is resource demanding. Fire Dynamics Simulator (FDS version 6.7.0) was used to simulate fire driven flow between two parallel vertical walls. Flame heights, thermal impact to the interior wall surface and upward flow velocities were predicted with FDS and compared with experimental results. The fire source was a propane burner with 8 × 391 mm2 gas outlet area. Heat release rates were 6.6 kW and 12.4 kW and the distance between the parallel walls was 40 mm. Two different convective heat transfer coefficient sub grid scale models available in FDS were investigated. In this study the cavity width to mesh cell size ratio was equal or above 10, resulting in good predictions of flame heights, upward flow velocities and wall temperatures. 2 mm grid resulted in 25% lower HRR in locations near the burner gas inlet, compared to 4 mm grid, indicating the importance of well resolved gas outlet boundary.
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| 6. |
- Livkiss, K., et al.
(författare)
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Uncertainties in modelling heat transfer in fire resistance tests : A case study of stone wool sandwich panels
- 2017
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Ingår i: Fire and Materials. - : Wiley. - 0308-0501. ; 41:7, s. 799-807
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Tidskriftsartikel (refereegranskat)abstract
- Modelling fire performance of building fire barriers would allow optimising the design solutions before performing costly fire resistance tests and promote performance-based fire safety engineering. Numerical heat conduction analysis is widely used for predicting the insulation capability of fire barriers. Heat conduction analysis uses material properties and boundary condition parameters as the input. The uncertainties in these input parameters result in a wide range of possible model outcomes. In this study, the output sensitivity of a heat conduction model to the uncertainties in the input parameters was investigated. The methodology was applied to stone wool core sandwich panels subjected to the ISO 834 standard fire resistance temperature/time curve. Realistic input parameter value distributions were applied based on material property measurements at site and data available in literature. A Monte Carlo approach and a functional analysis were used to analyse the results. Overall, the model is more sensitive to the boundary conditions than to the material thermal properties. Nevertheless, thermal conductivity can be identified as the most important individual input parameter.
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| 7. |
- Rosenstock, Nicholas P., et al.
(författare)
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Biological enhancement of mineral weathering by Pinus sylvestris seedlings - effects of plants, ectomycorrhizal fungi, and elevated CO2
- 2019
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Ingår i: Biogeosciences. - : Copernicus Publications. - 1726-4170 .- 1726-4189. ; 16:18, s. 3637-3649
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Tidskriftsartikel (refereegranskat)abstract
- Better understanding and quantifying the relative influence of plants, associated mycorrhizal fungi, and abiotic factors such as elevated CO2 on biotic weathering is essential to constraining weathering estimates. We employed a column microcosm system to examine the effects of elevated CO2 and Pinus sylvestris seedlings, with or without the ectomycorrhizal fungi Piloderma fallax and Suillus variegatus, on rhizosphere soil solution concentrations of low-molecular-weight organic acids (LMWOAs) and on the weathering of primary minerals. Seedlings significantly increased mineral weathering, as estimated from elemental budgets of Ca, K, Mg, and Si. Elevated CO2 increased plant growth and LMWOA concentrations but had no effect on weathering. Colonization by ectomycorrhizal fungi, particularly P. fallax, showed some tendency to increase weathering. LM-WOA concentrations correlated with seedling biomass across both CO2 and mycorrhizal treatments but not with total weathering. We conclude that nutrient uptake, which reduces transport limitation to weathering, is the primary mechanism by which plants enhanced weathering in this system. While the experimental system used departs from conditions in forest soils in a number of ways, these results are in line with weathering studies performed at the ecosystem, macrocosm, and microcosm scale, indicating that nutrient uptake by plants and microbes is an important biological mechanism by which mineral weathering is enhanced.
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