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"Flame"
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The island stallion's fury
Flame and Steve's secret island valley is discovered and invaded by a hard and vicious man, who is a threat to the island stallion, and his band.
Book
Uncovering global-scale risks from commercial chemicals in air
Commercial chemicals are used extensively across urban centres worldwide
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, posing a potential exposure risk to 4.2 billion people
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. Harmful chemicals are often assessed on the basis of their environmental persistence, accumulation in biological organisms and toxic properties, under international and national initiatives such as the Stockholm Convention
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. However, existing regulatory frameworks rely largely upon knowledge of the properties of the parent chemicals, with minimal consideration given to the products of their transformation in the atmosphere. This is mainly due to a dearth of experimental data, as identifying transformation products in complex mixtures of airborne chemicals is an immense analytical challenge
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. Here we develop a new framework—combining laboratory and field experiments, advanced techniques for screening suspect chemicals, and in silico modelling—to assess the risks of airborne chemicals, while accounting for atmospheric chemical reactions. By applying this framework to organophosphate flame retardants, as representative chemicals of emerging concern
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, we find that their transformation products are globally distributed across 18 megacities, representing a previously unrecognized exposure risk for the world’s urban populations. More importantly, individual transformation products can be more toxic and up to an order-of-magnitude more persistent than the parent chemicals, such that the overall risks associated with the mixture of transformation products are also higher than those of the parent flame retardants. Together our results highlight the need to consider atmospheric transformations when assessing the risks of commercial chemicals.
A new framework is proposed for assessing the risks of the atmospheric transformation products of commercial chemicals, combining laboratory and field experiments, advanced techniques for screening suspect chemicals, and in silico modelling.
Journal Article
Flame-Retardant Systems Based on Chitosan and Its Derivatives: State of the Art and Perspectives
During the last decade, the utilization of chitin, and in par0ticular its deacetylated form, i.e., chitosan, for flame retardant purposes, has represented quite a novel and interesting application, very far from the established uses of this bio-sourced material. In this context, chitosan is a carbon source that can be successfully exploited, often in combination with intumescent products, in order to provide different polymer systems (namely, bulky materials, fabrics and foams) with high flame retardant (FR) features. Besides, this specific use of chitosan in flame retardance is well suited to a green and sustainable approach. This review aims to summarize the recent advances concerning the utilization of chitosan as a key component in the design of efficient flame retardant systems for different polymeric materials.
Journal Article
Sooting turbulent jet flame: Characterization and quantitative soot measurements
Computational fluid dynamics (CFD) modelers require high-quality experimental data sets for validation of their numerical tools. Preferred features for numerical simulations of a sooting, turbulent test case flame are simplicity (no pilot flame), well-defined boundary conditions, and sufficient soot production. This paper proposes a non-premixed C2H 4/air turbulent jet flame to fill this role and presents an extensive database for soot model validation. The sooting turbulent jet flame has a total visible flame length of approximately 400 mm and a fuel-jet Reynolds number of 10,000. The flame has a measured lift-off height of 26 mm which acts as a sensitive marker for CFD model validation, while this novel compiled experimental database of soot properties, temperature and velocity maps are useful for the validation of kinetic soot models and numerical flame simulations. Due to the relatively simple burner design which produces a flame with sufficient soot concentration while meeting modelers' needs with respect to boundary conditions and flame specifications as well as the present lack of a sooting \"standard flame\", this flame is suggested as a new reference turbulent sooting flame. The flame characterization presented here involved a variety of optical diagnostics including quantitative 2D laser-induced incandescence (2D-LII), shifted-vibrational coherent anti-Stokes Raman spectroscopy (SV-CARS), and particle image velocimetry (PIV). Producing an accurate and comprehensive characterization of a transient sooting flame was challenging and required optimization of these diagnostics. In this respect, we present the first simultaneous, instantaneous PIV, and LII measurements in a heavily sooting flame environment. Simultaneous soot and flow field measurements can provide new insights into the interaction between a turbulent vortex and flame chemistry, especially since soot structures in turbulent flames are known to be small and often treated in a statistical manner. © 2011 Springer-Verlag.
Journal Article
Supergravity effects on flame propagation and structure in hydrogen/air mixtures
In the current work, we investigated hydrogen/air flame propagation under supergravity conditions. Results show that when gravity is in the same/opposite direction as flame propagation, it leads to acceleration/deceleration of the flame, and that such an effect could substantially modify the flame propagation and structure at high gravity levels. Furthermore, for the absolute and relative flame propagation speeds, the gravity-affected flame speed shows opposite trends as the absolute flame speed is more affected by the local induced flow field, while the relative flame speeds are controlled by the super-adiabatic or sub-adiabatic flame temperature. The gravity-affected thermal and chemical flame structures are also examined through the influence of the mixture equivalence ratio, pressure, and flame stretch.
Journal Article
Hydrodynamic theory of premixed flames propagating in closed vessels: flame speed and Markstein lengths
A hydrodynamic theory of premixed flame propagation within closed vessels is developed assuming the flame is much thinner than all other fluid dynamic lengths. In this limit, the flame is confined to a surface separating the unburned mixture from burned combustion products, and propagates at a speed determined from the analysis of its internal structure. Unlike freely propagating flames that propagate under nearly isobaric conditions, combustion in a closed vessel results in continuous increases in pressure, burning rate and flame temperature, and a progressive decrease in flame thickness. The flame speed is shown to depend on the voluminal stretch rate, which measures the deformation of a volume element of the flame zone, and on the rate of pressure rise. Both effects are modulated by pressure-dependent Markstein numbers that depend on heat release and mixture properties while capturing the effects of temperature-dependent transport and stoichiometry. The model applies to flames of arbitrary shape propagating in general flows, laminar or turbulent, within vessels of general configurations. The main limitation of hydrodynamic flame theories is the assumption that variations inside the flame zone due to chemistry or turbulence, which could potentially alter its internal structure, are physically unresolved. Nonetheless, the theory, deduced from physical first principles, identifies the various mechanisms involved in the combustion process as demonstrated in detailed discussions of planar flames propagating in rectangular channels and spherically expanding flames in spherical vessels. It also enables the construction of instructive models to numerically simulate the evolution of multi-dimensional and corrugated flames under confinement.
Journal Article
A Review of a Class of Emerging Contaminants: The Classification, Distribution, Intensity of Consumption, Synthesis Routes, Environmental Effects and Expectation of Pollution Abatement to Organophosphate Flame Retardants (OPFRs)
Organophosphate flame retardants (OPFRs) have been detected in various environmental matrices and have been identified as emerging contaminants (EC). Given the adverse influence of OPFRs, many researchers have focused on the absorption, bioaccumulation, metabolism, and internal exposure processes of OPFRs in animals and humans. This paper first reviews the evolution of various types of flame retardants (FRs) and the environmental pollution of OPFRs, the different absorption pathways of OPFRs by animals and humans (such as inhalation, ingestion, skin absorption and absorption), and then summarizes the environmental impacts of OPFRs, including their biological toxicity, bioaccumulation, persistence, migration, endocrine disruption and carcinogenicity. Based on limited available data and results, this study also summarizes the bioaccumulation and biomagnification potential of OPFRs in different types of biological and food nets. In addition, a new governance idea for the replacement of existing OPFRs from the source is proposed, seeking environmentally friendly alternatives to OPFRs in order to provide new ideas and theoretical guidance for the removal of OPFRs.
Journal Article
Recent Developments in Flame-Retardant Lignin-Based Biocomposite: Manufacturing, and characterization
Lignin with a phenolic structure can act as a fire retardant, but different origins of lignin and extraction methods impact the fire behavior capabilities. The thermal characteristics of lignin, such as glass transition (Tg) temperature, thermal degradation, molecular weight, lignin purity, and phenolic content, influence the capability of lignin as a flame retardant (FR) by causing significant char residue. However, lignin faced significant constraints in the final polymer to meet industry requirements, with the main issue being a lack of homogeneity when blending lignin with polymeric matrices. To improve the FR performance of lignin, various advances have been taken such as altering lignin with nitrogen and/or phosphorus chemicals, as well as shrinking lignin to the nanoscale to reduce lignin aggregation with matrices and obtaining considerable FR behavior in which FR system, lignin can present as a single component, lignin-based composite, modified lignin, and nano lignin. The present review addresses the manufacture of lignin as FR and the attributes of the product with lignin added to the system. It also covers the structure, source, extraction technique, physical-chemical properties, and chemical modification of lignin as an FR source, as well as the basic principle of flame retardancy, influencing factors (current development and application till the industrial analysis need of FR). Throughout this review, it aids in the discovery of a better strategy to introduce lignin as a source of bio-based FR for achieving the low cost in the fabrication method of FR.
Journal Article
Modeling of flame transfer function of a diverging premixed flame with developing flame speed under velocity disturbances
A theoretical study was conducted to examine the flame transfer function (FTF) of a diverging premixed flame subject to uniform and/or convective velocity disturbances considering developing turbulent flame speed. The FTF under uniform velocity disturbances with developing flame speed is less oscillatory compared with constant flame speed, and the magnitude of the aforementioned FTF is decreased more rapidly with an increase in turbulent time scale or flame length. The peak overshoot of the FTF under convective velocity disturbances is observed in a certain frequency range, which is known to be a typical nature of the FTF of a diverging flame under convective velocity disturbances. Such peak overshoot is quite sensitive to how the turbulent flame speed varies along the flame front in case of developing flame speed while the amplitude of the peak overshoot rarely changes with the mean flame length in case of constant flame speed.
Journal Article