Gaz parfait

Résumé

Le gaz parfait est un modèle thermodynamique décrivant le comportement des gaz réels à basse pression. Ce modèle a été développé du milieu du au milieu du et formalisé au . Il est fondé sur l'observation expérimentale selon laquelle tous les gaz tendent vers ce comportement à pression suffisamment basse, quelle que soit la nature chimique du gaz, ce qu'exprime la loi d'Avogadro, énoncée en 1811 : la relation entre la pression, le volume et la température est, dans ces conditions, indépendante de la nature du gaz. Cette propriété s'explique par le fait que lorsque la pression est faible, les molécules de gaz sont suffisamment éloignées les unes des autres pour que l'on puisse négliger les interactions électrostatiques qui dépendent, elles, de la nature du gaz (molécules plus ou moins polaires). De nombreux gaz réels vérifient avec une excellente approximation le modèle du gaz parfait dans les conditions normales. C'est le cas des gaz principaux de l'air, le diazote et le dioxygène

Source officielle

https://fr.wikipedia.org/wiki/Gaz_parfait

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Mixing of fresh (river) water and salty water (seawater or saline brine) in a control fashion would produces an electrical energy known as salinity gradient energy (SGE). Two main conversion technologies of SGE are membrane-based processes; pressure retarded osmosis (PRO) and reverse electrodialysis (RED). In PRO, semipermeable membranes placed between the two streams of solutions allow the transport of water from low-pressure diluted solution to high-pressure concentrated solution. RED requires two alternating semipermeable membranes that allow the diffusion of the ions but not the flow of H2O. Lifetime and power density of the semipermeable membrane are two main factors affecting on deployment of PRO and RED. Semipermeable membranes with lifetime greater than 10 years and power density higher than 5 W/m(2) would lead to faster development of this conversion technology. An exergy analysis of an SGE system of sea-river can be applied to calculate the maximum potential power for electricity generation. Seawater is taken as reference environment (global dead state) for calculating the exergy of water since the seawater is the final reservoir. Once the fresh water is mixed with water of the sea or lake it becomes unuseful for human, agricultural or industrial uses loses all its exergy. Aqueous sodium chloride solution model is used in this study to calculate the thermodynamic properties of seawater. This model does not consider seawater as an ideal model and provides accurate thermodynamics properties of sodium chloride solution. As a case study, exergy calculation of Iran's Urmia Lake- GadarChay River system. The chemical exergy analysis considers sodium chloride (NaCl) as main salt in the water of Lake Urmia. The sodium chloride concentration is more than 200 g/L in recent years. Based on the exergy results the potential power of this system is 329 MW. This results indicates a high potential for constructing power plant for salinity gradient energy conversion.

Amer Soc Mechanical Engineers2016

Chargement

3d transition-metal oxide materials with strong electron correlations and low dimensionality give rise to emerging exotic phases. Resonant inelastic X-ray scattering (RIXS) has developed as a powerful spectroscopic tool for probing the collective excitations in such correlated materials. The RIXS technique provides an ideal approach for assessing electronic instabilities in condensed matter. This thesis comprises the experimental RIXS response of the spin chain-ladder cuprates Sr14-xCax(Cu,Co)24O41 and frustrated honeycomb nickelate Na2Ni2TeO6. The spin and charge excitations of Sr14-xCaxCu24O41 (x=0 & 12.2) are studied by Cu L3-edge RIXS. With increasing Ca content, a crossover from collective two-triplon excitations (x=0) to a damped incoherent magnetic spectrum ~280 meV (x=12.2) in the ladders is uncovered from the RIXS spectra, dominated by spin-flip ÎS=1 scattering. With model calculations, the localized broad magnetic mode at x=12.2 is shown to be a consequence of enhanced elecrtronic localization. This is supported by polarization-dependent measurements, where the evaluated non-spin-flip ÎS=0 scattering is showing weight depletion below 1 eV. The RIXS spectral evolution suggests that a suppressed carrier mobility dominates the low-energy physics in Ca-rich phases. The low-energy excitations of Sr14Cu24O41 are also studied by O K-edge RIXS at the upper Hubbard band. The RIXS spectra show a sharp dispersing peak of similar energies to the ÎS=1 two-triplon excitations, and a broad non-dispersive mode at higher-energy. By comparing the experimental results to the existing theories of doped ladders, the observed spectral modes are attributed to interacting holon-spinon quasiparticles, with additional spectral contributions from the ÎS=0 multi-triplon bound states and continuum. These observations highlight the RIXS capability for resolving composite spin-charge quasiparticles and long-lived ÎS=0 magnetic excitations, which are difficult to detect by other experiments. Charge order and phonons for the two-leg ladders of Sr14(Cu,Co)24O41 are studied. At the ladder hole peak in O K-edge XAS signal, a concomitant elastic enhancement and phonon-softening is observed across all Co doping levels. The in-plane diffraction and phonon-softening response are found to enhance with increasing Co doping. Morevoer, the observed diffraction signal is further characterized by energy- and temperature-dependent measurements. Lastly, given the strong electron-phonon coupling (EPC) observed in O K-edge RIXS spectra, the EPC strength can be analyzed from the RIXS intensity decay of the phonon overtones . The observed in-plane resonant diffraction and inelastic phonon response strongly suggest an enhanced stripe order via magnetic impurities, reminiscent of the reports in CuO4 plaquettes. Electronic structure and EPC of the honeycomb nickelate Na2Ni2TeO6 are studied. Compared with current literature, the localized excitations (1-4 eV) in the Ni L3-edge RIXS spectra are dominated by the crystal-field splitting of a Ni2+ ion in octahedral coordination. At the O K-edge, the large EPC ~285 meV with 5 recognizable overtones (frequency of ~80 meV) are revealed in the RIXS spectra. The observed modes provide a systematic characterization of charge, orbital and lattice dynamics for a newly proposed frustrated antiferromagnet. This thesis has been carried out in a collaboration between the Paul Scherrer Institut and the Laboratory for Quantum Magnetism at EPFL.

EPFL2021

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The research described within this thesis is primarily motivated by two fields of science with reversed, yet complementary, approaches to addressing the same essential objective: manipulating and understanding the complex program of life. Whereas synthetic biology has to do with the bottom-up construction of living systems from a library of âpartsâ, systems biology takes a top-down, reverse-engineering analysis of the same processes within functioning cells to elucidate the crucial elements and interactions. Both perspectives have led to important contributions in learning how biological systems operate. Discoveries from these studies can have far-reaching implications, notably in medicine, manufacturing, energy, and the environment. One exciting outcome of the research efforts within synthetic biology is the ability to design genetic constructs encoding proteins with novel, optimized functions. Although advances have been made in predicting how a proteinâs amino acid sequence relates to its higher order structural form and behavior, experimental methods for protein engineering remain invaluable for evaluating computationally derived designs. Unfortunately, the design-build-test cycle for rational protein development is commonly a time, labor and resource intensive endeavor. This is primarily due to limitations in the ability to generate libraries of gene variants and bottlenecks in cell-based expression and quantitative screening of protein products. This thesis describes the development of a solid-phase gene assembly technique and its integration with microfluidic protein analysis to accelerate the prototyping of novel protein designs. The gene assembly method utilizes commodity-scale, chemically manufactured DNA, and operates without the need for ligase or restriction enzymes. As a bench top process amenable to scale up, the modularity of the assembly process allows the efficient and economical generation of expression-ready gene variants. We directly coupled this gene assembly pipeline to a microfluidic device to enable high-throughput, on-chip, cell-free protein expression, purification, and characterization. By circumventing molecular cloning and cell-based steps, the lag time between protein design and quantitative analysis was dramatically reduced. As a proof of concept, this protein engineering platform was applied towards the construction of over 400 artificial, engineered variants of C2H2 zinc finger (ZF) proteins. ZF protein domains are the most prevalent form of transcription factor (TF) in humans, and are found throughout the tree of life. They provide a convenient structure for refactoring due to their relatively small size and composability, and are an ideal model for exploring the biophysics of TF-DNA specificity. The ability to engineer ZF proteins makes them useful as programmable, DNA-targeting units for applications in biotechnology and synthetic biology. We demonstrate that although ZFPs can be readily engineered to recognize a particular DNA target, engineering the precise binding energy landscape remains a challenge. Additionally, we show that ZF-DNA binding affinity can be tuned independently of sequence specificity. Together, these results demonstrate the versatility of the coupled gene assembly and microfluidic analysis platform as a new tool for rational protein engineering.

EPFL2016

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EPFL2016

Amer Soc Mechanical Engineers2016

EPFL2021