The potentiality of reactive membranes for post combustion CO2 capture

CO2 industrial emissions have a severe impaction on the global warming due the important CO2 greenhouse effect. Post combustion gases represent one of the largest industrial source of CO2 emitted to the atmosphere, currently 30 gigatonsper year. CO2 Flue gas composition varies widely from 4 to 30% depending on its origin. In order to capture and valorise CO2, efficient processes with high capture ratio, high selectivity and low energetic footprint must be developed. Among the process used for CO2 recovery and concentration, membrane separation appears as a promising option. Membranes are environmentally friendly and have high potential for breakthroughs in energy consumption and overall cost, are solvent-free and are compatible for retrofit strategy. However, the CO2 purity limitations with commercial membrane or the actual energy requirement limit the use of membranes in CO2 capture. In order to improve membrane separation performance, Facilitated Transport Membranes (FTM) have been recently developed such as the Fixed Site Carrier Membrane (FSCM based on amine carrier fixed by covalent bond inside the dense polymeric membrane). In this case, facilitated transport is specific to CO2 mass transfer. Amine reacts with CO2 in presence of high relative humidity and makes a new complex, HCO3-. The anion crosses through the membrane by hopping mechanism. In the low pressure permeate side, the reversible reaction occurs and CO2 is released. Please click Additional Files below to see the full abstract

Accounting for sizing parameters and boundary geometry in the bond graph representation of energetic elements

International audienceIn this paper we present how to take into account parameters and variables that were not initially present in the bond graph representation of some components. These bond graph considerations are justified mainly by design arguments but from the automatics point of view this is closely related to the state representation concept. We present this idea through the examples of a mechanical spring and a simple thermodynamic system. In each case one solution is to substitute a multiport energy storage element to the initial one port element. It emphasizes the close relationship between the order of this component and the output variables that we want to observe in this component

Herschel observations of EXtra-Ordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey Toward Orion KL II. Chemical Implications

We present chemical implications arising from spectral models fit to the Herschel/HIFI spectral survey toward the Orion Kleinmann-Low nebula (Orion KL). We focus our discussion on the eight complex organics detected within the HIFI survey utilizing a novel technique to identify those molecules emitting in the hottest gas. In particular, we find the complex nitrogen bearing species CH$_{3}$CN, C$_{2}$H$_{3}$CN, C$_{2}$H$_{5}$CN, and NH$_{2}$CHO systematically trace hotter gas than the oxygen bearing organics CH$_{3}$OH, C$_{2}$H$_{5}$OH, CH$_{3}$OCH$_{3}$, and CH$_{3}$OCHO, which do not contain nitrogen. If these complex species form predominantly on grain surfaces, this may indicate N-bearing organics are more difficult to remove from grain surfaces than O-bearing species. Another possibility is that hot (T$_{\rm kin}$$\sim$300 K) gas phase chemistry naturally produces higher complex cyanide abundances while suppressing the formation of O-bearing complex organics. We compare our derived rotation temperatures and molecular abundances to chemical models, which include gas-phase and grain surface pathways. Abundances for a majority of the detected complex organics can be reproduced over timescales $\gtrsim$ 10$^{5}$ years, with several species being under predicted by less than 3$\sigma$. Derived rotation temperatures for most organics, furthermore, agree reasonably well with the predicted temperatures at peak abundance. We also find that sulfur bearing molecules which also contain oxygen (i.e. SO, SO$_{2}$, and OCS) tend to probe the hottest gas toward Orion KL indicating the formation pathways for these species are most efficient at high temperatures.Comment: 31 pages, 6 figures, 1 Table, accepted to the Astrophysical Journa

Intensified post-combustion CO2 capture: potential of hollow fiber membrane contactor for absorption and stripping steps

Post-combustion CO2 capture (PCC) is an important strategy in mitigating greenhouse effect. The robustness of packed columns makes it the standard technology for the gas-liquid absorption of CO2, using aqueous amine solutions as liquid absorbents. Even though it is not the best performing chemical solvent, monoethanolamine (MEA) at 30% wt. is currently considered as the benchmark solvent for PCC [1]. However, the treatment of large quantities of flue gases requires itself equipment of a large size. Hollow fibre membrane contactors (HFMC) are considered as one of the most promising strategies for intensified CO2 absorption process, due to their significantly higher interfacial area than that of packed columns, allowing to reduce the equipment size [2]. HFMC technology has been widely investigated for the absorption step under laboratory conditions (e.g. high reactant excess) [3]. However, despite the potential advantages of membrane contactors, very few investigations have studied implementing this technology within an industrial framework. The performance of CO2 absorption and stripping using HFMC under industrial conditions is still unknown. To fill this lack, adiabatic multicomponent one-dimensional models have been developed to estimate the performance of both absorption and stripping steps using HFMC and packed columns. The modelling of both technologies is based on coupled mass and heat transfer balances. Indeed, this is standard in packed columns modelling, however, neglecting the thermal effects appears to be common in HFMC modelling [4], [5]. The intensification potential of HFMC for both absorption and stripping steps was therefore estimated in industrial conditions. Please click Additional Files below to see the full abstract

Applying causality and bicausality to multi-port elements in Bond Graphs

International audienceThe introduction of the bicausality concept in the bond graph language has allowed new analytical methodologies of a system, for instance in the context of model inversion, mechatronic system sizing and control. The causality assignment generally imposes the way these constitutive relations have to be used. In the case of linear multi-port elements, derivative causality or of bicausality is not necessarily possible. The conditions for the existence of a causal configuration are related to the form of the constitutive relation of the multi-port element. In this paper, we propose to inspect this condition and then to focus on the use of the causality applied to the linear multi-port elements. We show that the constitutive relations of any linear multi-port element may be used to determine quickly what kind of causality assignment does exist and what could be determined using different schemes of calculus. It clearly appears that this approach may be applied in other contexts and may have interesting applications on system sizing, identification and control

Large and uniform optical emission shifts in quantum dots externally strained along their growth axis

We introduce a method which enables to directly compare the impact of elastic strain on the optical properties of distinct quantum dots (QDs). Specifically, the QDs are integrated in a cross-section of a semiconductor core wire which is surrounded by an amorphous straining shell. Detailed numerical simulations show that, thanks to the mechanical isotropy of the shell, the strain field in a core section is homogeneous. Furthermore, we use the core material as an in situ strain gauge, yielding reliable values for the emitter energy tuning slope. This calibration technique is applied to self-assembled InAs QDs submitted to incremental tensile strain along their growth axis. In contrast to recent studies conducted on similar QDs stressed perpendicularly to their growth axis, optical spectroscopy reveals 5-10 times larger tuning slopes, with a moderate dispersion. These results highlight the importance of the stress direction to optimise QD response to applied strain, with implications both in static and dynamic regimes. As such, they are in particular relevant for the development of wavelength-tunable single photon sources or hybrid QD opto-mechanical systems

Innovate contactor for CO2 recovery

Innovate contactor for CO2 recover

Metadata Systems for Data Lakes: Models and Features

International audienceOver the past decade, the data lake concept has emerged as an alternative to data warehouses for storing and analyzing big data. A data lake allows storing data without any predefined schema. Therefore, data querying and analysis depend on a metadata system that must be efficient and comprehensive. However, metadata management in data lakes remains a current issue and the criteria for evaluating its effectiveness are more or less nonexistent.In this paper, we introduce MEDAL, a generic, graph-based model for metadata management in data lakes. We also propose evaluation criteria for data lake metadata systems through a list of expected features. Eventually, we show that our approach is more comprehensive than existing metadata systems

Autoinducer production and quorum-sensing dependent phenotypes of Pseudomonas aeruginosa vary according to isolation site during colonization of intubated patients

<p>Abstract</p> <p>Background</p> <p><it>Pseudomonas aeruginosa </it>frequently colonizes and is responsible for severe ventilator-associated pneumonia in intubated patients. A quorum-sensing (QS) circuit, depending on the production of the two QS-signaling molecules (autoinducers, AIs) 3-oxo-C₁₂-HSL and C₄-HSL, regulates the production by <it>P. aeruginosa </it>of several virulence factors and is required for biofilm formation. Therefore QS-inhibition has been suggested as a new target for preventive and/or therapeutic strategies. However the precise role of QS during colonization and subsequent infections of intubated patients remains unclear.</p> <p>Results</p> <p>We wondered whether QS is active during colonization of intubated patients, and whether <it>P. aeruginosa </it>isolates growing inside the biofilm covering the intubation devices and those resident in the lungs of colonized patients differ in their QS-dependent phenotypes. We collected the intubation devices of eight patients colonized by <it>P. aeruginosa</it>. We detected 3-oxo-C₁₂-HSL on eight, and C₄-HSL on six of these devices. In three of these patients we also obtained <it>P. aeruginosa </it>isolates from tracheal aspirates at the time of extubation (n = 18), as well as isolates from the intubation devices (n = 25). We genotyped these isolates, quantified their AIs production, and determined three QS-dependent phenotypes (adherence capacity, biofilm and elastase production). The production of 3-oxo-C₁₂-HSL was consistently increased for isolates from the intubation devices, whereas the production of C₄-HSL was significantly higher for isolates from tracheal aspirates. Isolates from tracheal aspirates produced significantly higher amounts of elastase but less biofilm, and had a marginally reduced adhesion capacity than isolates from the intubation devices. Levels of 3-oxo-C₁₂-HSL and elastase production correlated statistically for tracheal intubation isolates, whereas levels of 3-oxo-C₁₂-HSL production and adhesion ability, as well as biofilm production, correlated weakly amongst intubation device isolates.</p> <p>Conclusion</p> <p>Our findings demonstrate that autoinducers are produced during the colonization of intubated patients by <it>P. aeruginosa</it>. The microenvironment, in which <it>P. aeruginosa </it>grows, may select for bacteria with different capacities to produce autoinducers and certain QS-dependent phenotypes. QS-inhibition might therefore affect differently isolates growing inside the biofilm covering intubation devices and those resident in the lungs.</p