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- Brandon, Daniel, et al.
(författare)
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Glueline Integrity in Fire
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Mass timber is an increasingly popular material for large and tall buildings. Such buildings typically have higher consequence classes than buildings of traditional timber construction and have higher fire resistance requirements. Architectural demands pushing towards having large surface areas of visible and exposed wood lead to additional fire safety challenges. Previous research has shown that some mass timber products can exhibit glue line integrity failure when exposed to fire, while other mass timber products are not prone to this phenomenon. In practice, it is important to know whether glue line integrity failure occurs, to be able to suitably perform fire resistance calculations (for example using the upcoming version of Eurocode 5) and to be able to predict the fire exposure and duration of fires in real buildings (needed for a performance-based approach). The research presented in this report studies the suitability of a furnace test for determining whether products exhibit glue line integrity failure or not. The study includes the determination of a conservative test duration, by comparisons with conditions of a statistically severe compartment fire. Furthermore, a round robin study with twelve fire tests in furnaces of different labs at different scales, fired with different fuel types has been performed. For all tests, the specimens were made of a mass timber material that does not exhibit glue line integrity failure. The average mass loss rate per unit of exposed area and the average charring rate were determined and assessment criteria were evaluated. Comparisons of the round robin study results have been made, against those of a specific CLT product that has been shown to maintain glue line integrity in numerous furnace and compartment fire tests and a recommendation of a pass/fail criterion is given for a future classification standard.
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- Brandon, Daniel, et al.
(författare)
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High-Fire-Resistance Glulam Connections for Tall Timber Buildings
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Tall timber buildings generally require fire resistance ratings of 90 minutes, 120 minutes or more. The vast majority of fire tested structural timber connections, however, did not reach a fire resistance that was relevant for these buildings. Commonly timber connections between glued laminated timber members comprise of exposed steel fasteners, such as bolts, screws, nails and dowels. However, it has previously been concluded that connections with exposed steel fasteners, generally do not achieve fire resistance ratings of 30 minutes and are, therefore, inadequate to be implemented in tall timber buildings without fire encapsulation. The research project presented in this report consists of four connection fire tests that are designed to achieve structural fire resistance ratings of 90 minutes, using different design strategies. This goal was achieved for all tested column-beam connections. A single test of a moment resisting connection did not lead to a fire resistance rating of 90 minutes, due to timber failure at the smallest cross-section after 86 minutes. The low temperature of the steel fasteners and the limited rotation of the connection, however, suggest that the connection would have been capable of achieving a 90 minutes fire resistance rating if larger beam cross-sections would be used.
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- Burenhult, Niclas
(författare)
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Hur talade forntidens folk?
- 1997
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Ingår i: Populär Arkeologi. - 0281-014X. ; 97:4, s. 13-16
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Tidskriftsartikel (populärvet., debatt m.m.)
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- Perme, Tina, et al.
(författare)
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Genomic and phenotypic characterisation of invasive neonatal and colonising group B Streptococcus isolates from Slovenia, 2001-2018
- 2020
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Ingår i: BMC Infectious Diseases. - : BioMed Central. - 1471-2334. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Group B Streptococcus (GBS) is the leading cause of invasive neonatal disease in the industrialized world. We aimed to genomically and phenotypically characterise invasive GBS isolates in Slovenia from 2001 to 2018 and contemporary colonising GBS isolates from screening cultures in 2018.METHODS: GBS isolates from 101 patients (invasive isolates) and 70 pregnant women (colonising isolates) were analysed. Basic clinical characteristics of the patients were collected from medical records. Antimicrobial susceptibility and phenotypic capsular serotype were determined. Whole-genome sequencing was performed to assign multilocus sequence types (STs), clonal complexes (CCs), pathogenicity/virulence factors, including capsular genotypes, and genome-based phylogeny.RESULTS: Among invasive neonatal disease patients, 42.6% (n = 43) were females, 41.5% (n = 39/94) were from preterm deliveries (< 37 weeks gestation), and 41.6% (n = 42) had early-onset disease (EOD). All isolates were susceptible to benzylpenicillin with low minimum inhibitory concentrations (MICs; ≤0.125 mg/L). Overall, 7 serotypes were identified (Ia, Ib, II-V and VIII); serotype III being the most prevalent (59.6%). Twenty-eight MLST STs were detected that clustered into 6 CCs. CC-17 was the most common CC overall (53.2%), as well as among invasive (67.3%) and non-invasive (32.9%) isolates (p < 0.001). CC-17 was more common among patients with late-onset disease (LOD) (81.4%) compared to EOD (47.6%) (p < 0.001). The prevalence of other CCs was 12.9% (CC-23), 11.1% (CC-12), 10.5% (CC-1), 8.2% (CC-19), and 1.8% (CC-498). Of all isolates, 2.3% were singletons.CONCLUSIONS: A high prevalence of hypervirulent CC-17 isolates, with low genomic diversity and characteristic profile of pathogenicity/virulence factors, was detected among invasive neonatal and colonising GBS isolates from pregnant women in Slovenia. This is the first genomic characterisation of GBS isolates in Slovenia and provides valuable microbiological and genomic baseline data regarding the invasive and colonising GBS population nationally. Continuous genomic surveillance of GBS infections is crucial to analyse the impact of IND prevention strategies on the population structure of GBS locally, nationally, and internationally.
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- Schnitter, Claudia, et al.
(författare)
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Effect of low-energy ion assistance on the properties of sputtered ZrB2 films
- 2022
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Ingår i: Vacuum. - : Pergamon-Elsevier Science Ltd. - 0042-207X .- 1879-2715. ; 195
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Tidskriftsartikel (refereegranskat)abstract
- Zirconium diboride (ZrB2) films have been deposited by direct current magnetron sputtering (DCMS) from a ZrB2 compound target on Al2O3 (0001) substrates held at 600, 700, 800, and 900 degrees C, and with two different axial magnetic field strengths, 34 and 104 G, generated using a coil surrounding the substrate. Plasma probe measurements show an increase of the ion fluxes on floating-potential substrates of the two different configurations by a factor of 2.8 for 104 G compared to 34 G, while the ion energy remained relatively constant at approximate to 12 eV. Time-of-flight elastic recoil detection analysis (ToF-ERDA) show that films deposited with a magnetic field of 34 G are highly overstoichiometric with B/Zr ratios approximate to 2.4, while films deposited with 104 G exhibit a B/Zr ratios approximate to 2.1. The levels of oxygen and carbon in the films are below 1 at. % irrespective of growth conditions. X-ray diffraction (XRD) 0/20 scans, complemented by pole figure measurements, reveal that all deposited films are 0001-oriented. XRD 0/20 scans of the 000t peak intensities and co (rocking-curve) widths show increased ZrB2 crystal quality with increasing temperature for both magnetic field strengths. Minimum electrical resistivity of approximate to 100 p omega cm is achieved for an axial magnetic field of 104 G, independent of temperature.
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