Particle size emissions from PVC electrical cable fires

Electrical cables are in every building and form a significant part of fire loads and can through electrical faults be the first item burnt in some fires. PVC insulated cables are still quite common in buildings and this work investigates Prysmian PVC cables. Deaths and injuries in fires are dominated by the influence of toxic smoke emissions and most of the work on the hazards of smoke are concerned with the toxic gases such as CO. However, fires are large producers of particulate material at levels over 1000 times that in controlled combustion and there is little knowledge of the role of ultra-fine particles in fires and none at all for electrical cable fires. The cone calorimeter fire material testing equipment was used in the present work, which is an ideal test procedure for particle size measurement, as controlled dilution (100/1) of the fire products occurs which enabled diluted samples to be used for particulate number measurement. The Cambustion DMS500 transient particle size analyser was used to determine the particle size distribution. The cone calorimeter uses a 100mm square test specimen and this was filled with 10 100mm lengths of the PVC cable. The test specimen was on a load cell so that the mass burn rate was determined. The cone calorimeter ignites the specimen using a conical electrical heater that is calibrated to achieve a control radiant heat flux on the test specimen, which was 35 kW/m2 in the present work. The fire occurred in a restricted air supply with an insulated air box around the 100mm square test fire. A chimney on the conical heater exit was used to obtain a raw gas sample for toxic gas analysis using a heated Gasmet FTIR. For gases dilution is undesirable as oxidation of the toxic gases may occur. For particles the chimney temperature was too low for carbon oxidation to be significant. The dilution process also condenses unburned hydrocarbons and carbonyl species, which may form nano aerosols and these may be the source of the 10nm particles measured in the present work. HCl is a major product of PVC fires and hence hydrochloric acid aerosols are likely in the particulate measurements. In previous work of the authors, PVC cable fires were investigated with free ventilation and HCl yields of about 50% were measured with Acrolein at 5% yield and Formaldyhyde at 3%. Thus there are plenty of liquid aerosol possible in the diluted products of PVC fires. The results showed a large nuclei number peak at about 10nm. The coarse particle peak only started after flaming combustion occurred and this was initially at 200nm, which increased to 300nm after 1000s. The 10nm peak was high for the first 200s, then dropped dramatically and slowly reformed later in the fire and at the end of the fire was very high with a low coarse particle peak. The FTIR gas species will be used to speculate on the likely composition of the nanoaerosols as a function of time in the fire

Smoke Particle Size Distribution in Pine Wood Fires

There is a growing concern about the impact of ultra- fine particulates released from fires on the health of humans in fires and the related environmental pollution. However, there is no requirement to measure particle mass or number from legislated test fires and hence there is minimum information in the literature on this toxic hazard in fires. This work compares particulates generated from freely ventilated and restricted ventilation pine wood fires using the cone calorimeter. The standard cone calorimeter with freely ventilated combustion was modified by adding a discharge pipe to the cone heater that enabled direct fire product sampling from the cone outlet. The controlled atmosphere cone calorimeter was used for the restricted ventilation fire with metered air fed to the enclosure around the test area. Both tests used a radiant heat flux of 35kW/m2. Real-time particulate number and size distribution were measured using the Cambustion DMS 500 particle electrical mobility spectrometer. The particulate size distribution showed a peak of ultra-fine aerosol particles of <100 nm in the early stage of the fire development and then changed to the larger size (100-1000 nm) with a peak of 200 nm as the fire progressed. The restricted ventilation fire generated more particles. There were high numbers of 20 nm particles throughout the fire and these have the greatest health risks. Toxic gases were also measured from the raw exhaust gases using a heated Gasmet FTIR gas analyser

Rich biomass combustion: Gaseous and particle number emissions

The cone calorimeter is a standard test method for material behaviour in fires. The principle of the cone calorimeter is to use an electric radiant heater to raise the temperature of the combustion zone and ignite the fuel. 35 kW/m 2 was used in the present work, as this has been previously shown to be sufficient to establish fully developed combustion of biomass materials such as wood. As one of the main fire loads is wood and wood is the dominant biomass for energy generation, it is reasonable to use the cone calorimeter to characterize the combustion of biomass on a small scale and pine was used in the present work. The cone calorimeter was used in the controlled atmosphere mode with an enclosure around the test biomass that enabled the air flow for biomass combustion to be controlled at 19.2 g/m 2 s, which corresponds to a combustion heat release rate HRR of 57 kW/m 2 , assuming all the oxygen in the air is consumed. This air flow will be shown to generate rich combustion at a metered equivalence ratio, Ø of about 2, which is comparable with the first gasification stage of biomass two stage burning in log burners and pellet burners, where air is added downstream of the gasification stage of biomass combustion. Soot emissions are generated in this rich gasification stage burning and potentially oxidized in the oxidation second stage burning. The rich burning gasification zone particulate emissions were analysed for number size distribution using the Cambustion DMS 500 particle size analyser. The exit from the controlled combustion zone was extended in a 75 mm diameter chimney where a mean gas sample was taken. A heated Gasmet FTIR was used for gas composition analysis, using a heated sample line, filter and pump from the sample point to the analyser. The particles emitted were sampled after the second stage combustion from entrained air into the chimney discharge gases into a dilution tunnel with a fixed gas flow rate of 24 l/s, which gave a dilution ratio of the primary combustion gases of 150/1 which is required for nano-particle size analysis. A Cambustion DMS500 electrical mobility particle number and size instrument was used with size resolution from 5 to 1000 nm. The present results show that in the rich burning first stage chimney sample there were very high levels of 20 nm nanoparticles, 1 × 10 10 /cc, and an accumulation mode peak at 200 nm. The presence of the 20 nm particles makes the particulate emissions extremely toxic

Toxic Gas Emissions from Plywood Fires

Toxic emissions from four construction plywoods were investigated using a freely ventilated cone calorimeter with raw predilution hot gas sampling. Each plywood sample was exposed to the conical heater of the cone calorimeter radiating at 35 kw/m². Rich mixtures occurred in some of the tests, these rich mixtures produced high concentrations of toxic gases. The 4 samples had different peak heat release rate HRR, but similar steady state HRR. The elemental analysis of the four samples showed that they had different nitrogen content, indicating different glues were used. Plywood B had the highest N content of 6.43%, which resulted in the highest HCN concentration. The most important toxic species were CO, HCN, acrolein, formaldehyde and benzene on both an LC₅₀ and COSHH₁₅min basis

Pine Wood Crib Fires: Toxic Gas Emissions Using a 5m3 Compartment Fire

Toxic emissions from pinewood crib fires were determined using heated FTIR gas analysis from a 5 m3 compartment fire with an air opening equivalent to 5% of the compartment cross-sectional area (V2/3) in the floor of the compartment and a vent in the ceiling layer, with the air inlet controlling the flow. A 20 mm square pine wood crib size of 400 × 400 × 260 mm was investigated. The crib was ignited using a small ethanol pool fire. The flaming fire had a peak HRR of 40 kW and average ceiling temperature of 400 °C. The fire was lean overall at the peak HRR and the fire self-extinguished through lack of air with subsequent smouldering combustion. In spite of the lean combustion in the fire, very high toxic emissions were determined with an FEC LC50 of >6. The peak toxicity occurred just before the fire self-extinguished and the key toxic emissions were CO and formaldehyde for deaths, while formaldehyde and acrolein were the most important for impairment of escape

Involvement of glomerular renin−angiotensin system (RAS) activation in the development and progression of glomerular injury

Recently, there has been a paradigm shift away from an emphasis on the role of the endocrine (circulating) renin−angiotensin system (RAS) in the regulation of the sodium and extracellular fluid balance, blood pressure, and the pathophysiology of hypertensive organ damage toward a focus on the role of tissue RAS found in many organs, including kidney. A tissue RAS implies that RAS components necessary for the production of angiotensin II (Ang II) reside within the tissue and its production is regulated within the tissue, independent of the circulating RAS. Locally produced Ang II plays a role in many physiological and pathophysiological processes such as hypertension, inflammation, oxidative stress, and tissue fibrosis. Both glomerular and tubular compartments of the kidney have the characteristics of a tissue RAS. The purpose of this article is to review the recent advances in tissue RAS research with a particular focus on the role of the glomerular RAS in the progression of renal disease

An African Muslim Saint and his Followers in France

This paper explores the practice of Islam among a relatively understudied group of Muslim migrants in France, the Halpulaaren, some of whom have been living in France for more than three decades. Drawing on field research in Senegal, Mali and France, the author considers the contexts for Halpulaaren migration to France, including the West African background to such migration and the situation migrants face in France. The author focuses on a Halpulaaren Muslim religious leader from Senegal, Mansour Baro, who has a reputation as a living Muslim saint, and his followers in France. Tierno Mansour is one of a handful of the most esteemed leaders of the Tijaniyya Sufi order in Senegal. The appeal of this saint, who annually visits Europe, for his followers in France is examined in order to try and understand some of the ways of being Muslim in the shadow of the global city with both its promises and constraints. [Journal abstract]ASC – Publicaties niet-programma gebonde

Whole genome identification of Mycobacterium tuberculosis vaccine candidates by comprehensive data mining and bioinformatic analyses

<p>Abstract</p> <p>Background</p> <p><it>Mycobacterium tuberculosis</it>, the causative agent of tuberculosis (TB), infects ~8 million annually culminating in ~2 million deaths. Moreover, about one third of the population is latently infected, 10% of which develop disease during lifetime. Current approved prophylactic TB vaccines (BCG and derivatives thereof) are of variable efficiency in adult protection against pulmonary TB (0%–80%), and directed essentially against early phase infection.</p> <p>Methods</p> <p>A genome-scale dataset was constructed by analyzing published data of: (1) global gene expression studies under conditions which simulate intra-macrophage stress, dormancy, persistence and/or reactivation; (2) cellular and humoral immunity, and vaccine potential. This information was compiled along with revised annotation/bioinformatic characterization of selected gene products and <it>in silico </it>mapping of T-cell epitopes. Protocols for scoring, ranking and prioritization of the antigens were developed and applied.</p> <p>Results</p> <p>Cross-matching of literature and <it>in silico</it>-derived data, in conjunction with the prioritization scheme and biological rationale, allowed for selection of 189 putative vaccine candidates from the entire genome. Within the 189 set, the relative distribution of antigens in 3 functional categories differs significantly from their distribution in the whole genome, with reduction in the Conserved hypothetical category (due to improved annotation) and enrichment in Lipid and in Virulence categories. Other prominent representatives in the 189 set are the PE/PPE proteins; iron sequestration, nitroreductases and proteases, all within the Intermediary metabolism and respiration category; ESX secretion systems, resuscitation promoting factors and lipoproteins, all within the Cell wall category. Application of a ranking scheme based on qualitative and quantitative scores, resulted in a list of 45 best-scoring antigens, of which: 74% belong to the dormancy/reactivation/resuscitation classes; 30% belong to the Cell wall category; 13% are classical vaccine candidates; 9% are categorized Conserved hypotheticals, all potentially very potent T-cell antigens.</p> <p>Conclusion</p> <p>The comprehensive literature and <it>in silico</it>-based analyses allowed for the selection of a repertoire of 189 vaccine candidates, out of the whole-genome 3989 ORF products. This repertoire, which was ranked to generate a list of 45 top-hits antigens, is a platform for selection of genes covering all stages of <it>M. tuberculosis </it>infection, to be incorporated in rBCG or subunit-based vaccines.</p