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A serial of tests were carried out to evaluate the effect of specimen mass on the test results for PMMA conducted in a micro-scale combustion calorimeter. Seven heating rates were used to test specimens of mass ranging from 0.5 to 6.0 mg with nominal interval of 0.5 mg. Eighty-five specimens were tested. Heat release rate, onset temperature, temperature at maximum heat release rate, total heat release, and heat release capacity were determined. The influence of specimen mass at each heating rate was analyzed. Specimen mass influences the maximum heat release rate, onset temperature, and temperature at maximum heat release rate significantly. The higher the heating rate, the greater the influence. Reliable results could be obtained as long as the specimen mass is more than 1 mg with oxygen concentration above 5 %; thus, the oxygen concentration limit might be extended from 10 to 5 %.

As animals evolved to use oxygen as the main strategy to produce ATP through the process of mitochondrial oxidative phosphorylation, the ability to adapt to fluctuating oxygen concentrations is a crucial component of evolutionary pressure. Three mitophagy receptors, FUNDC1, BNIP3 and NIX, induce the removal of dysfunctional mitochondria (mitophagy) under prolonged hypoxic conditions in mammalian cells, to maintain oxygen homeostasis and prevent cell death. However, the evolutionary origins and structure-function relationships of these receptors remain poorly understood. Here, we found that FUN14 domain-containing proteins are present in archaeal, bacterial and eukaryotic genomes, while the family of BNIP3 domain-containing proteins evolved from early animals. We investigated conservation patterns of the critical amino acid residues of the human mitophagy receptors. These residues are involved in receptor regulation, mainly through phosphorylation, and in interaction with LC3 on the phagophore. Whereas FUNDC1 may be able to bind to LC3 under the control of post-translational regulations during the early evolution of vertebrates, BINP3 and NIX had already gained the ability for LC3 binding in early invertebrates. Moreover, FUNDC1 and BNIP3 each lack a layer of phosphorylation regulation in fishes that is conserved in land vertebrates. Molecular evolutionary analysis revealed that BNIP3 and NIX, as the targets of oxygen sensing HIF-1α, showed higher rates of substitution in fishes than in mammals. Conversely, FUNDC1 and its regulator MARCH5 showed higher rates of substitution in mammals. Thus, we postulate that the structural traces of mitophagy receptors in land vertebrates and fishes may reflect the process of vertebrate transition from water onto land, during which the changes in atmospheric oxygen concentrations acted as a selection force in vertebrate evolution. In conclusion, our study, combined with previous experimental results, shows that hypoxia-induced mitophagy regulated by FUDNC1/MARCH5 might use a different mechanism from the HIF-1α-dependent mitophagy regulated by BNIP3/NIX.

International audience; Upwelling of cold, nutrient-rich water from the oxygen minimum zone (OMZ) off Peru sustains the world’shighest production of forage fish, mostly composed of anchovy (Engraulis ringens). However, the potentialimpacts of climate change on upwelling dynamics and thus fish productivity in the near future areuncertain. Here, we reconstruct past changes in fish populations during the last 25,000 years to unraveltheir response to changes in OMZ intensity and productivity. We quantified and identified fish scales andbones deposited in laminated sediments from Pisco (Peru) with an average sampling resolution of 20.4years (±7.1). The records span the Last Glacial Maximum to the recent Holocene and thus encompass avariety of combinations of productivity, oxygen, and global temperature. Our results reveal thatproductivity appears to be the main factor controlling small pelagic fish abundance, while sub-surfaceoxygenation affects mainly anchovy and likely sardine populations. Lower productivity and higher oxygenconcentrations during the glacial resulted in lower total fish productivity, whereas higher productivity anda stronger OMZ in some time intervals during the Holocene resulted in higher fish abundances. A varietyof different conditions between these two oceanographic end members indicate preferred environmentalconditions for a variety of small pelagic fishes. There is no evidence in our record for an out of phaserelationship between anchovy and sardine at the timescales examined in the present study. Anchovy havebeen the predominant small pelagic fish throughout the record, at least over centennial to millennialtimescales. Its abundance reached a maximum during the Current Warm Period, an era characterized byhigh productivity and intense OMZ conditions. Thus, industrial fisheries developed during a period ofexceptional productivity in relation to that of the last 25 kyr. The records reveal that dramatic decreasesin pelagic fish abundances have occurred in response to past large-scale climate changes than thoseobserved in the instrumental period, which suggests that future climate change may result in substantialchanges in ecosystem structure.

International audience; As a part of an effort to determine the energy balance at the pool fire surface in compartments, a series of fire experiments were conducted to study heat flux of the flame in a vitiated environment formed with air and combustion products gases. This paper presents experimental results of the burning behaviour of a heptane pool fire in a reduced scale compartment equipped with a mechanical ventilation network. Measurements of heat fluxes, fuel mass loss rate, oxygen concentration and temperature are performed for heptane fires of 0.26 and 0.3 m diameter pans at different ventilation flow rates. An original method to separate effects of the radiant heat flux of the flame and of the external heat feedback to the fuel surface is developed. This was achieved by using an additional heat flux measurement located under the pool fire. A correlation was also developed to determine the temperature rise on the plume centerline in the compartment as a function of the heat release rate. The results indicate a decrease in the fuel mass loss rate, flame temperature and heat fluxes to the fuel surface as the oxygen concentration measured near the fuel decreases by varying the air refresh rate of the compartment. The flame radiation fraction shows a similar behaviour, whereas the convective fraction of the flame heat flux increases when oxygen concentration decreases. Based on these experimental findings, it was discussed that any classification of the burning regime of a pool fire should consider both the effects of pan diameter and the burning response to vitiated air. © 2013 Elsevier Ltd. All rights reserved.

International audience; The oxygen concentration in the oxidizer stream (O-2 + N-2) of laminar coflow ethylene diffusion flames is varied from 17% to 35% in order to study its influence on the flame height, the soot formation/oxidation processes, the smoke point characteristics, and the vertical distributions of radiative flux at a distance of 6.85 cm from the flame axis. Measured values for all the investigated parameters are compared with the predictions provided by a numerical model based on a two-equation semiempirical acetylene-based soot model and on the statistical narrow-band correlated-k model to compute thermal radiation. Predictions are in overall reasonable agreement with the experiments for oxygen indices in the range 19-35%, whereas all the investigated parameters are significantly underestimated for an oxygen index of 17%. Measured flame heights based on CH* emission below, at, or slightly above the smoke point, as well as predicted stoichiometric flame heights, are found to be proportional to xi = (V) over dot(f)[D-infinity In(1 + 1/S)](-1) (T-infinity/T-ad)(0.67), where (V) over dot(f), D-infinity, S, and T-ad are the volumetric flow rate of ethylene, the diffusion coefficient at ambient temperature, the stoichiometric molecular air-to-fuel ratio, and the adiabatic flame temperature. Soot formation processes are found to increase with the oxygen index, leading to higher values of the maximum soot volume fraction and the peak integrated soot volume fraction. In addition, the latter is reached at a nondimensional height (normalized by xi of approximately 0.05, regardless of the oxygen index within the investigated range. Two regimes are evidenced: The first regime, occurring for oxygen indices lower than 25%, is dominated by soot oxidation and is characterized by an enhancement in both the maximum soot volume fraction and the fuel flow rate at the smoke point with the oxygen index. The second regime, occurring for oxygen indices higher than 25%, is dominated by soot formation; the rate of increase in the maximum soot volume fraction with the oxygen concentration is lower than in the first regime, whereas the fuel flow rate at the smoke point decreases. Finally, the peak of radiative flux increases with the oxygen index, but its rate of increase is also found to be considerably reduced for oxygen indices greater than 25%. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Although many coral reefs have shifted from coral-to-algal dominance, the consequence of such a transition for coral–algal interactions and their underlying mechanisms remain poorly understood. At the microscale, it is unclear how diffusive boundary layers (DBLs) and surface oxygen concentrations at the coral–algal interface vary with algal competitors and competitiveness. Using field observations and microsensor measurements in a flow chamber, we show that coral (massive Porites) interfaces with thick turf algae, macroalgae, and cyanobacteria, which are successful competitors against coral in the field, are characterized by a thick DBL and hypoxia at night. In contrast, coral interfaces with crustose coralline algae, conspecifics, and thin turf algae, which are poorer competitors, have a thin DBL and low hypoxia at night. Furthermore, DBL thickness and hypoxia at the interface with turf decreased with increasing flow speed, but not when thick turf was upstream. Our results support the importance of water-mediated transport mechanisms in coral–algal interactions. Shifts towards algal dominance, particularly dense assemblages, may lead to thicker DBLs, higher hypoxia, and higher concentrations of harmful metabolites and pathogens along coral borders, which in turn may facilitate algal overgrowth of live corals. These effects may be mediated by flow speed and orientation.

The rates of bacterial growth in nature are often restricted by low concentrations of oxygen or carbon substrates. In the present study the metabolic properties of 24 isolates that had been isolated using various concentrations of 3-chlorobenzoate, benzoate and oxygen as well as using continuous culture at high and low growth rates were determined to investigate the effects of these parameters on the metabolism of monoaromatic compounds. Bacteria were enriched from different sampling sites and subsequently isolated. In batch culture this was done both under low oxygen (2% O-2) and air-saturated concentrations. Chemostat enrichments were performed under either oxygen or 3-chlorobenzoate limiting conditions. Bacteria metabolizing aromatics with gentisate or protocatechuate as intermediates (gp bacteria) as well as bacteria metabolizing aromatic compounds via catechols (cat bacteria) were isolated from batch cultures when either benzoate or 3CBA were used as C sources, regardless of the enrichment conditions applied. In contrast, enrichments performed in chemostats at low dilution rates resulted in gp-type organisms only, whereas at high dilution rates cat-type organisms were enriched, irrespective of the oxygen and 3-chlorobenzoate concentration used during enrichment. It is noteworthy that the gp-type of bacteria possessed relatively low Irm, values on 3CBA and benzoate along with relatively high substrate and oxygen affinities for these compounds. This is in contrast with cat-type of bacteria, which seemed to be characterized by high maximum specific growth rates on the aromatic substrates and relatively high apparent half saturation constants. In contrast, bacteria degrading chlorobenzoate via gentisate or protocatechuate may possibly be better adapted to conditions leading to growth at reduced rates such as low oxygen and low substrate concentrations. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

Microbiologically Influenced Corrosion (MIC) is the term used for the phenomenon in which corrosion is initiated and/or accelerated by the activities of microorganisms. MIC is a very serious problem for the ship industry as it reduces structural lifetime in combination with safety risks for crewmembers or inspection personal and increases maintenance costs. This review aims to focus on the importance and mechanisms of MIC in ship ballast tanks (SBTs). First section presents a literature review of general aspects of ballast tanks: structural properties including predominant environmental conditions. Second section summarizes the fundamental corrosion mechanisms within SBTs from an electrochemical point of view. Third section links microbial corrosion mechanism with electrochemical processes summarizing types of microorganisms, mechanisms of MIC and possible triggers for biofilm formation within this enclosed environment. For this an integral model, linking environmental parameters such as oxygen concentration, corrosion rate, nutrient availability and the microbial species of this environment is introduced in this paper. Fourth section gives an outlook on surface treatment and coating application in SBT. The last section considers the practical aspects of MIC detection and possible counterstrategies for engineers/operators and inspection personal. This paper gives a comprehensive overview of MIC processes in ship ballast tanks addressing engineers, equipment manufacturers and operators by offering practical solutions for an appropriate SBT management. © 2013 Elsevier Ltd.

Microbiologically Influenced Corrosion (MIC) is the term used for the phenomenon in which corrosion is initiated and/or accelerated by the activities of microorganisms. MIC is a very serious problem for the ship industry as it reduces structural lifetime in combination with safety risks for crewmembers or inspection personal and increases maintenance costs. This review aims to focus on the importance and mechanisms of MIC in ship ballast tanks (SBTs). First section presents a literature review of general aspects of ballast tanks: structural properties including predominant environmental conditions. Second section summarizes the fundamental corrosion mechanisms within SBTs from an electrochemical point of view. Third section links microbial corrosion mechanism with electrochemical processes summarizing types of microorganisms, mechanisms of MIC and possible triggers for biofilm formation within this enclosed environment. For this an integral model, linking environmental parameters such as oxygen concentration, corrosion rate, nutrient availability and the microbial species of this environment is introduced in this paper. Fourth section gives an outlook on surface treatment and coating application in SBT. The last section considers the practical aspects of MIC detection and possible counterstrategies for engineers/operators and inspection personal. This paper gives a comprehensive overview of MIC processes in ship ballast tanks addressing engineers, equipment manufacturers and operators by offering practical solutions for an appropriate SBT management. © 2013 Elsevier Ltd.

AlN and GaN thin films were deposited by plasma-enhanced atomic layer deposition using trimethylmetal precursors. The films were found to have high oxygen incorporation, which was attributed to oxygen contamination related to the plasma system. The choice of nitrogen containing plasma gas (N2, N2/H2 or NH3) determined the severity of oxygen incorporation into deposited films. Lowest oxygen concentrations were attained for AlN and GaN thin films using NH3 and N2 plasma, respectively. Initial experiments have shown that GaN thin films with low impurity concentrations can be deposited when plasma-related oxygen contamination is avoided by the use of an alternative plasma source. © The Electrochemical Society.

Dilution of partially-premixed combustion (PPC) using different combinations of excess air (λ>1) and exhaust gas recirculation (EGR) was investigated in a single-cylinder, heavy-duty diesel engine equipped with common-rail fuel injection. The experiments were limited to a single fuel injection event using ultra-low sulphur diesel fuel at a low engine load (∼3 bar BMEP) and engine speeds of 900 and 1350 rpm. The start of injection was varied to optimize the combustion performance and emissions. The experimental results show that increasing air dilution at constant EGR reduced BSFC slightly. CO and HC emissions decreased significantly due to the increased oxygen concentration, but NOx and soot emissions increased. For a given level of charge dilution, there was an optimal EGR rate to minimize BSFC. NOx emissions decreased significantly as the proportion of dilution by EGR was increased, but CO and HC emissions increased due to the reduced in-cylinder temperature and oxygen concentration, which increased the combustion duration. Copyright © 2012 by Her Majesty the Queen in Right of Canada., ASME 2012 Internal Combustion Engine Division Spring Technical Conference, ICES 2012, 6 May 2012 through 9 May 2012, Torino, Piemonte

An analysis of in-cylinder gas density and oxygen mass concentration (YO 2 ) impact on the mixing and oxidation processes and the final soot emissions in conventional high temperature diffusive Diesel combustion conditions is presented in this paper. Parametrical tests were performed on a single cylinder heavy duty research engine. The density was modified adjusting the boost pressure following two approaches, maintaining the YO 2 either before or after the combustion process. The YO 2 was modified by diluting fresh air with exhaust gas maintaining a constant density. The possibility of controlling the soot emissions combining both parameters (YO 2 and density) is evaluated and, in a final part, the NO X emission results are also addressed. Results show that YO 2 has a strong effect on both mixing and oxidation processes while density affects principally the mixing process. Both parameters affect the final soot emissions. The density modification through adjustment of boost pressure modifies the trapped mass and has a strong impact on the evolution of YO 2 (thus on the evolution of the mixing process) during combustion. If the density is increased maintaining constant the YO 2 at the beginning of the combustion, the NO X -Soot trade-off is enhanced.

The effect of O2+, H2+ O 2+, and N2+ O2 + ion-beam irradiation of carbon nanotubes (CNTs) films on the chemical and electronic properties of the material is reported. The CNTs were grown by the chemical vapor deposition technique (CVD) on silicon TiN coated substrates previously decorated with Ni particles. The Ni decoration and TiN coating were successively deposited by ion-beam assisted deposition (IBAD) and afterwards the nanotubes were grown. The whole deposition procedure was performed in situ as well as the study of the effect of ion-beam irradiation on the CNTs by x-ray photoelectron spectroscopy (XPS). Raman scattering, field-effect emission gun scanning electron microscopy (FEG-SEM), and field emission (FE) measurements were performed ex situ. The experimental data show that: (a) the presence of either H2+ or N2 + ions in the irradiation beam determines the oxygen concentration remaining in the samples as well as the studied structural characteristics; (b) due to the experimental conditions used in the study, no morphological changes have been observed after irradiation of the CNTs; (c) the FE experiments indicate that the electron emission from the CNTs follows the Fowler-Nordheim model, and it is dependent on the oxygen concentration remaining in the samples; and (d) in association with FE results, the XPS data suggest that the formation of terminal quinone groups decreases the CNTs work function of the material. © 2011 American Institute of Physics. Fil:Escobar, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Goyanes, S.N. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Candal, R.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Alvarez, F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

The synthesis, structural framework, magnetic and oxygen-sensing properties of a lithium naphthalocyanine (LiNc) radical probe are presented. LiNc was synthesized in the form of a microcrystalline powder using a chemical method and characterized by electron paramagnetic resonance (EPR) spectroscopy, magnetic susceptibility, powder X-ray diffraction analysis, and mass spectrometry. X-Ray powder diffraction studies revealed a structural framework that possesses long, hollow channels running parallel to the packing direction. The channels measured approximately 5.0 � 5.4 2 in the two-dimensional plane perpendicular to the length of the channel, enabling diffusion of oxygen molecules (2.9 � 3.9 2) through the channel. The powdered LiNc exhibited a single, sharp EPR line under anoxic conditions, with a peak-to-peak linewidth of 630 mG at room temperature. The linewidth was sensitive to surrounding molecular oxygen, showing a linear increase in pO2 with an oxygen sensitivity of 31.2 mG per mmHg. The LiNc microcrystals can be further prepared as nano-sized crystals without the loss of its high oxygen-sensing properties. The thermal variation of the magnetic properties of LiNc, such as the EPR linewidth, EPR intensity and magnetic susceptibility revealed the existence of two different temperature regimes of magnetic coupling and hence differing columnar packing, both being one-dimensional antiferromagnetic chains but with differing magnitudes of exchange coupling constants. At a temperature of ?50 K, LiNc crystals undergo a reversible phase transition. The high degree of oxygen-sensitivity of micro- and nano-sized crystals of LiNc, combined with excellent stability, should enable precise and accurate measurements of oxygen concentration in biological systems using EPR spectroscopy. � 2009 The Royal Society of Chemistry.

The rates of bacterial growth in nature are often restricted by low concentrations of oxygen or carbon substrates. In the present study the metabolic properties of 24 isolates that had been isolated using various concentrations of 3-chlorobenzoate, benzoate and oxygen as well as using continuous culture at high and low growth rates were determined to investigate the effects of these parameters on the metabolism of monoaromatic compounds. Bacteria were enriched from different sampling sites and subsequently isolated. In batch culture this was done both under low oxygen (2% O-2) and air-saturated concentrations. Chemostat enrichments were performed under either oxygen or 3-chlorobenzoate limiting conditions. Bacteria metabolizing aromatics with gentisate or protocatechuate as intermediates (gp bacteria) as well as bacteria metabolizing aromatic compounds via catechols (cat bacteria) were isolated from batch cultures when either benzoate or 3CBA were used as C sources, regardless of the enrichment conditions applied. In contrast, enrichments performed in chemostats at low dilution rates resulted in gp-type organisms only, whereas at high dilution rates cat-type organisms were enriched, irrespective of the oxygen and 3-chlorobenzoate concentration used during enrichment. It is noteworthy that the gp-type of bacteria possessed relatively low Irm, values on 3CBA and benzoate along with relatively high substrate and oxygen affinities for these compounds. This is in contrast with cat-type of bacteria, which seemed to be characterized by high maximum specific growth rates on the aromatic substrates and relatively high apparent half saturation constants. In contrast, bacteria degrading chlorobenzoate via gentisate or protocatechuate may possibly be better adapted to conditions leading to growth at reduced rates such as low oxygen and low substrate concentrations. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

This quality assessment of the Skagerrak-Kattegat is mainly based on recent results obtained within the framework of the Swedish multidisciplinary research projekt ‘Large-scale environmental effects and ecological processes in the Skagerrak-Kattegat’ completed with relevant data from other research publications. The results show that the North Sea has a significant impact on the marine ecosystem in the Skagerrak and the northern Kattegat. Among environmental changes recently documented for some of these areas are: increased nutrient concentrations, increased occurrence of fast-growing filamentous algae in coastal areas affecting nursery and feeding conditions for fish, declining bottom water oxygen concentrations with negative effects on benthic fauna, and sediment toxicity to invertebrates also causing physiological responses in fish. It is concluded that, due to eutrophication and toxic substances, large-scale environmental changes and effects occur in the Skagerrak-Kattegat area.