Thermal and geometrical features of jet fires

Abstract: In many severe accidents involving explosions or large fires, jet fires have been the first step of a domino effect sequence: a recent historical analysis has shown that among the accidents registered in the data bases, in approximately 50% of the cases in which it was a jet fire it caused another event with severe effects. However, the knowledge of jet fires essential features –behaviour, effects– is still rather poor. In this communication, the results obtained with relatively large jet fires (with flame length up to 10 m) are discussed. The fuel was propane, and both sonic and subsonic jet exit velocities were obtained from different outlet diameters. The distribution of the temperatures of the flame main axis was measured with a set of thermocouples. The jet fires were filmed with a videocamera registering visible light (VHS) and a thermographic camera (IR). The main flame geometrical features were analyzed as a function of the jet main variables, as well as the thermal effects (thermal radiation intensity as a function of distance).Postprint (published version

Radiant heat from propane jet fires

Sonic propane jet fire experiments were carried out in absence of wind, with visible flame length ranging between 2.2 and 8.1 m. The thermal radiation intensity increased with the mass flow rate and the flame length. The net heat released was also computed and a correlation for the flame length as a function of Q is proposed. The surface emissive power and the fraction of heat irradiated were estimated by applying the solid flame model, assuming the flame to be a cylinder. The variation of the emissive power as a function of flame length was found to follow a linear equation. The fraction of heat irradiated η was obtained from the value of the total radiative power; its average value for sonic propane gas flames was 0.07.Peer ReviewedPostprint (published version

Role of serotiny on Pinus pinaster Aiton germination and its relation to mother plant age and fire severity

erotiny degree may hypothetically depend on mother plant age and fire severity, and fire severity can strongly affect the regeneration of Pinus pinaster Aiton, which is an obligate seeder species with aerial seed banks stocked in cones showing a certain degree of serotiny. The main objective of this study was to evaluate the effect of serotiny and mother plant age on seed germination of P. pinaster in relation to fire severity. For this purpose, cones were collected in two stands from mother trees of different ages. Serotinous cones were opened in oven at increasing temperatures to determine the number of seeds released. The length of cones and the number and weight of seeds were measured. Seeds from both classes of mother plant age were subjected to 34 different treatments simulating different fire severity levels, and their germination was recorded. The results showed that serotiny was significantly higher in cones from young mother trees. Seed germination in the control groups from serotinous cones was always higher than that from non-serotinous cones without thermal shock. Fire severity decreased seed germination as fire severity increases in both mother age classes. Mother plant age was related to the serotiny level, which was higher in young than in old trees, suggesting a strong selection in the population due to a recent fire.This work is part of the research projects AGL2013-48189-C2-2-R (Ministerio de Economía y Competividad, Madrid, Spain, and ERDF founding), AGL2017-86075-C2-2-R (Ministerio de Ciencia, Educación y Universidades, Madrid, Spain, and ERDF founding), LE001P17 (Junta de Castilla y León, Valladolid, Spain), ED431C2019/07 and ED431E 2018/09 (Xunta de Galicia, Santiago de Compostela, Spain)S

Fire effects on germination response of the native species Daucus carota and the invasive alien species Helichrysum foetidum and Oenothera glazioviana

Fire is an ecological factor that affects ecosystem structure and functioning and determines later recovery of the ecosystem through the modification of biological processes, such as seed germination and seedling establishment. Another factor that modifies ecosystems is the presence of invasive alien species, which easily colonize new habitats after disturbances such as forest fires. Within this research, we analysed the germination response to fire of three species that share a habitat, one native species (Daucus carota L.) and two invasive alien species (Helichrysum foetidum (L.) Moench and Oenothera glazioviana Micheli) to identify and compare the effects of fire on the germination of these three species. For this purpose, germination tests were performed by using seeds treated with heat, smoke, charcoal and ash, simulating conditions of forest fires. The three species showed slightly different responses to fire factors. At high levels, heat and ash prevented the germination of the three species. In contrast, intermediate heat shocks and some smoke treatments stimulated O. glazioviana germination, while the other species remained unaffected. H. foetidum presented high germination success for most treatments. The difference in the germination response of the three species can change the current balance among three species in natural fire-prone ecosystems, contributing to the spread of O. glazioviana and H. foetidum to new areas and potentially reducing native D. carota populations.This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness, the Spanish Ministry of Science, Innovation and Universities, the Castilla y León Regional Government, the Galicia Regional Government and the European Regional Development Fund (ERDF) in the framework of the GESFIRE (AGL2013-48189-C2-2-R), FIRESEVES (AGL2017-86075-C2-2-R) and SEFIRECYL (LE001PE17) projects, the Competitive Reference Group BIOAPLIC (ED431C2019/07) and the Strategic Researcher Cluster BioReDeS (ED431E 2018/09)S

A new morphologic classification of the alveolar ridge after distraction osteogenesis in human patients. A 17 years retrospective case series study

To perform a morphologic classification based on the results of bone augmentation after a distraction osteogenesis. Thirty-four (34) patients (24 women and 10 men; mean age, 47.1 years (SD=9.5); age range, 23 to 62 years) underwent a total of 42 alveolar ridge distractions before the placement of a total of 89 dental implants. Ridge bone morphology was evaluated as the main ordinal variable. Chi-squared, Kruskal-Wallis and ANOVA one-way test were used. Category I (30.95%): consisted of wide alveolar rim and no bone defects Category II (28.57%): wide alveolar rim, lateral bone surface concavity. Category III (23.81%): narrow alveolar rim, lateral bone surface concavity. Category IV (2.38 %): distraction transport segment forming a bridge, without bone formed beneath and requiring guided bone regeneration. Category V (9.52%): return of the transport segment to its initial position due to the reverse rotation of the distractor screw. Category VI (4.76 %): distraction transport segment completely lost. Subcategory D (28.57%), consisted of lingual deviation of the distraction axis, occurring in any of the categories I to IV. More men (76.9 %) presented with category I (p<0.001). The use of the chisel resulted mainly in categories I and II (69.4 %) (p<0.001). GBR was only required in 23.1 % of the cases in Category I (p=0.011). The bone height achieved decreases as the category increases, due to the accompanying osteogenic limitations (p<0.001). The implants placed in category I were longer 11.5 ± 0.9 mm (CI95% 10.9-11.9 mm) compared to those placed in category III with a length of 10.4 ± 1.5 mm (CI95% 9.5-11.4 mm) (p=0.035). The alveolar ridge after distraction osteogenesis could be divided into six morphologic categories which provide a useful basis for decision-making regarding implant placement

Fire Severity Drives the Natural Regeneration of Cytisus scoparius L. (Link) and Salix atrocinerea Brot. Communities and the Germinative Behaviour of These Species

Research Highlights: Data indicated that fire severity modulates natural regeneration of Cytisus scoparius and Salix atrocinerea communities and drives much stronger effects on the germination of the dominant species. Background and Objectives: Previous studies demonstrated that fire severity induces different behaviours in plant species. Mother plant age is an important feature that must also be considered in plans of forest restoration. The objectives were to determine, in field studies, the effect of fire severity on the natural regeneration of C. scoparius and S. atrocinerea communities, to know the role of mother plant age on the germination of seeds of C. scoparius and S. atrocinerea, and to quantify their germination response at different levels of fire severity, in laboratory settings. Material and Methods: We have analysed the role of fire severity on the natural regeneration of C. scoparius and S. atrocinerea communities considering cover and height. Forty 30 × 30 m plots were randomly located in C. scoparius and S. atrocinerea communities. Fire severity on the germination of dominant species was tested through different levels of smoke, charcoal, ash, and heat. Results: High severity reduced the vertical cover and growth in height of the two communities and favoured the increase of cover of woody species in the C. scoparius community and herbaceous species in the S. atrocinerea community. Mother plant age determined germination percentages of C. scoparius seeds. Germination of C. scoparius was increased by moderate heat, and heat and smoke; and fire severity greatly reduced germination of S. atrocinerea. Conclusions: The regeneration responses after fire were largely controlled by interactions between the fire severity and the individual species regeneration strategies. For restoration purposes, C. scoparius seeds should be treated with 80 °C and smoke for 10 min, in order to increase germination; however, Salix seeds should be used without treatment and immediately after dispersionThis work was supported by the Spanish Ministry of Economy, Industry and Competitiveness, the Spanish Ministry of Science, Innovation and Universities, the Castilla y León Regional Government, the Galicia Regional Government and the European Regional Development Fund (ERDF) in the framework of the GESFIRE (AGL2013-48189-C2-2-R), FIRESEVES (AGL2017-86075-C2-2-R) and SEFIRECYL (LE001PE17) projects and the Competitive Reference Group BIOAPLIC (ED431C2019/07) and the Strategic Researcher Cluster BioReDeS (ED431E 2018/09)S

Germinative behaviour of Acacia dealbata Link, Ailanthus altissima (Mill.) Swingle and Robinia pseudoacacia L. in relation to fire and exploration of the regenerative niche of native species for the control of invaders

Invasion of forest ecosystems by invader plants and forest fires are two of the most serious environmental problems in the world. Climate change is believed to strongly influence these processes, and the invasibility of invasive alien plants (IAPs) is likely to enhance landscape degradation. Therefore, it is urgent to study the germinative behaviour of invasive alien plants in relation to fire and detect possible barrier species of IAPs among native species. Tree species are usually the most damaging group of invasive alien plants. Acacia dealbata Link, Ailanthus altissima (Mill.) Swingle and Robinia pseudoacacia L. are 3 very damaging exotic invader trees in Europe and many other parts of the world. Therefore, the germination behaviour (germination percentage, viability pregermination, viability postgermination and germination rate) of these three species was experimentally studied against different products associated with fire (heat, smoke, ash and charcoal). The germination of A. dealbata and R. pseudoacacia was strongly stimulated by heat, while smoke, ash and charcoal barely changed the control values. None of these factors stimulated germination in A. altissima. Very high temperatures inhibited seed germination of the three species. The germination of R. pseudoacacia seeds was faster than that of A. dealbata and A. altissima seeds. Of the three species studied, A. dealbata and R. pseudoacacia have greater invasibility than A. altissima. A key role in invasive plant control research is to provide information to guide the decisions of forest managers involved in restoration. A possible solution is to use the biotic resistance of native vegetation to control biological invasions. For this purpose and based on extensive bibliographic revision, the regenerative niches of the three invasive species (germination, seedling growth and adult height) were compared with those of native European species to identify candidates for barrier species of IAPs between native species. Among the native species of Europe with characteristics in their regenerative niche suitable to successfully compete against these IAPs are tall shrub species such as Adenocarpus lainzii (Castrov.) Castrov., Cytisus multiflorus (L'Her.) or Cytisus striatus (Hill) Rothm. and tree species such as Corylus colurna L., Pinus sylvestris L. and Quercus ilex L. Therefore, the sowing of a good combination of shrub and tree species, selected according to their geographical distribution, could be an effective ecological measure to control the invasion of IAPs in burned areas. This information can be very valuable for implementing restoration measures in burned areas and should be verified with field experimentsThis work was supported by the Spanish Ministry of Science and Innovation, the Galicia Regional Government, the European Regional Development Fund, European Union (ERDF) and Castilla y León Regional Government in the framework of the FIRESEVES (AGL2017-86075-C2-2-R) and WUIFIRECYL (LE005P20) projects and the Competitive Reference Group BIOAPLIC (ED431C 2019/07) and the Strategic Researcher Cluster BioReDeS (ED431E 2018/09)S

A survey of biosecurity measures and serological status for bovine viral diarrhoea virus and bovine herpesvirus 1 on dairy cattle farms in north-west and north-east Spain

Biosecurity is a key measure to reduce and prevent the introduction of diseases to farms and minimise spread of diseases within a herd. The aim of the study was to characterise the current application of biosecurity measures on dairy cattle farms in Spain along with their bovine viral diarrhoea and infectious bovine rhinotracheitis status. Data on biosecurity measures for 124 dairy herds were collected using a questionnaire. The sanitary status of these farms for bovine viral diarrhoea and infectious bovine rhinotracheitis was also assessed using antibody ELISA. Data were analysed using multiple correspondence analysis and a two-step cluster analysis. Three main clusters of farms were identified: clusters 1 and 2 included herds of small and intermediate sizes. These, particularly cluster 1, showed the most deficiencies in the control of vehicles and visitors. However, laboratory tests were always performed on purchased animals. Cluster 3 had the largest herd sizes, with somewhat better biosecurity control of vehicles and visitors. However, farms in this cluster also purchased the most animals, sometimes without testing, and hired external workers more often. The study indicated that, in the study population, there are serious shortcomings in the application of biosecurity measures on dairy farms, exposing them to disease transmission. This survey also highlights regional and herd size-related differences in the implementation of biosecurity. Collecting data is an important first step to identification of specific weaknesses in different farm typologies, and an adequate follow-up is needed to ensure that measures are implemented correctly on farms

Protumorigenic effects of Snail-expression fibroblasts on colon cancer cells

et al.Snail1 is a transcriptional factor that plays an important role in epithelial–mesenchymal transition and in the acquisition of invasive properties by epithelial cells. In colon tumors, Snail1 expression in the stroma correlates with lower specific survival of cancer patients. However, the role(s) of Snail1 expression in stroma and its association with patients' survival have not been determined. We used human primary carcinoma-associated fibroblasts (CAFs) or normal fibroblasts (NFs) and fibroblast cell lines to analyze the effects of Snail1 expression on the protumorigenic capabilities in colon cancer cells. Snail1 expression was higher in CAFs than in NFs and, as well as α-SMA, a classic marker of activated CAFs. Moreover, in tumor samples from 50 colon cancer patients, SNAI1 expression was associated with expression of other CAF markers, such as α-SMA and fibroblast activation protein. Interestingly, coculture of CAFs with colon cells induced a significant increase in epithelial cell migration and proliferation, which was associated with endogenous SNAI1 expression levels. Ectopic manipulation of Snail1 in fibroblasts demonstrated that Snail1 expression controlled migration as well as proliferation of cocultured colon cancer cells in a paracrine manner. Furthermore, expression of Snail1 in fibroblasts was required for the coadjuvant effect of these cells on colon cancer cell growth and invasion when coxenografted in nude mice. Finally, cytokine profile changes, particularly MCP-3 expression, in fibroblasts are put forward as mediators of Snail1-derived effects on colon tumor cell migration. In summary, these studies demonstrate that Snail1 is necessary for the protumorigenic effects of fibroblasts on colon cancer cells.This research was supported by the PI12/02037, Fundación Científica AECC, SAF2010-20750, S2010/BMD-2344, RTICC-RD12/0036/0041 and by the Fundación Banco Santander. Antonio García de Herreros’ laboratory was supported by RTICC-RD12/0036/0005 and SAF 2010-16089. Ma Jesús Larriba’s laboratory was supported by RD12/0036/0021. Cristina Peña and José Miguel García are recipients of Miguel Servet Contracts from the Instituto de Salud Carlos III.Peer reviewe

Swine influenza virus infection dynamics in two pig farms; results of a longitudinal assessment

In order to assess the dynamics of influenza virus infection in pigs, serological and virological follow-ups were conducted in two whole batches of pigs from two different farms (F1 and F2), from 3 weeks of age until market age. Anti-swine influenza virus (SIV) antibodies (measured by ELISA and hemagglutination inhibition) and nasal virus shedding (measured by RRT-PCR and isolation in embryonated chicken eggs and MDCK cells) were carried out periodically. SIV isolates were subtyped and hemagglutinin and neuraminidase genes were partially sequenced and analyzed phylogenetically. In F1, four waves of viral circulation were detected, and globally, 62/121 pigs (51.2%) were positive by RRT-PCR at least once. All F1 isolates corresponded to H1N1 subtype although hemagglutination inhibition results also revealed the presence of antibodies against H3N2. The first viral wave took place in the presence of colostral-derived antibodies. Nine pigs were positive in two non-consecutive sampling weeks, with two of the animals being positive with the same isolate. Phylogenetic analyses showed that different H1N1 variants circulated in that farm. In F2, only one isolate, H1N2, was detected and all infections were concentrated in a very short period of time, as assumed for a classic influenza outbreak. These findings led us to propose that influenza virus infection in pigs might present different patterns, from an epidemic outbreak to an endemic form with different waves of infections with a lower incidence