Changes in the composition of gut-associated microbial communities are associated with many human illnesses, but the factors driving dysbiosis remain incompletely understood. One factor governing the ...microbiota composition in the gut is bile. Bile acids shape the microbiota composition through their antimicrobial activity and by activating host signaling pathways that maintain gut homeostasis. Although bile acids are host-derived, their functions are integrally linked to bacterial metabolism, which shapes the composition of the intestinal bile acid pool. Conditions that change the size or composition of the bile acid pool can trigger alterations in the microbiota composition that exacerbate inflammation or favor infection with opportunistic pathogens. Therefore, manipulating the composition or size of the bile acid pool might be a promising strategy to remediate dysbiosis.
•A comprehensive model is proposed to investigate the heat and mass transfer mechanisms in WAAM process.•The main phenomena in the arc plasma are modelled including the droplet creation, its ...detachment and fly to the melt pool, as well as the deposition build-up during a multi-layered process.•The major role played by the droplet falling onto the melt pool and its behavior is discussed.•The model shows that the action of the droplets strongly influences the melt pool size, the fluid flow, and the temperature field in the deposit and so cannot be neglected in the model.
In this study, a numerical model of Wire Arc Additive Manufacturing has been developed to obtain the geometry of the part as well as its temperature field from the operating parameters. This predictive model takes into account electromagnetism, fluid flow and heat transfer in the arc and the melt pool. The Lorentz forces, shear stress, arc pressure, and Joule effect are calculated. This model is developed using the COMSOL Multiphysics® software. In order to simulate the addition of layer-by-layer material and the strong topological changes, the level set interface tracking method is used. This model aims to simulate the build-up of a 304 stainless steel rod starting from the operating parameters in the case of a pulsed currents. The detachment of droplets of the deposited metal and their fall along the vertical axis are modelled to predict the geometry and the thermal history of the workpiece. The "material supply / cooling" cycles between each layer are simulated. To validate this model, the geometry and the temperature field are analysed and compared to experimental data.
The high-efficiency capabilities of multijunction laser power converters are demonstrated for high-power applications with an optical input of around 1470 nm. The InP-based photovoltaic power ...converting III-V semiconductor devices are designed here, with 10 lattice-matched subcells (PT10-InGaAs/InP), using thin InGaAs absorbing layers connected by transparent tunnel junctions. The results confirm that such long-wavelength power converter devices are capable of producing electrical output voltages greater than 4–5 V. The characteristics are compatible with common electronics requirements, and the optical input is well suited for propagation over long distances through fiber-based optical links. Conversion efficiencies of ~49% are measured at electrical outputs exceeding 7 W for an input wavelength of 1466 nm at 21 °C. The Power Converter Performance Chart has been updated with these PT10-InGaAs/InP results.
Cholinesterases (ChEs) display a hysteretic behavior with certain substrates and inhibitors. Kinetic cooperativity in hysteresis of ChE-catalyzed reactions is characterized by a lag or burst phase in ...the approach to steady state. With some substrates damped oscillations are shown to superimpose on hysteretic lags. These time dependent peculiarities are observed for both butyrylcholinesterase and acetylcholinesterase from different sources. Hysteresis in ChE-catalyzed reactions can be interpreted in terms of slow transitions between two enzyme conformers E and E′. Substrate can bind to E and/or E′, both Michaelian complexes ES and E’s can be catalytically competent, or only one of them can make products. The formal reaction pathway depends on both the chemical structure of the substrate and the type of enzyme. In particular, damped oscillations develop when substrate exists in different, slowly interconvertible, conformational, and/or micellar forms, of which only the minor form is capable of binding and reacting with the enzyme. Biphasic pseudo-first-order progressive inhibition of ChEs by certain carbamates and organophosphates also fits with a slow equilibrium between two reactive enzyme forms. Hysteresis can be modulated by medium parameters (pH, chaotropic and kosmotropic salts, organic solvents, temperature, osmotic pressure, and hydrostatic pressure). These studies showed that water structure plays a role in hysteretic behavior of ChEs. Attempts to provide a molecular mechanism for ChE hysteresis from mutagenesis studies or crystallographic studies failed so far. In fact, several lines of evidence suggest that hysteresis is controlled by the conformation of His438, a key residue in the catalytic triad of cholinesterases. Induction time may depend on the probability of His438 to adopt the operative conformation in the catalytic triad. The functional significance of ChE hysteresis is puzzling. However, the accepted view that proteins are in equilibrium between preexisting functional and non-functional conformers, and that binding of a ligand to the functional form shifts equilibrium towards the functional conformation, suggests that slow equilibrium between two conformational states of these enzymes may have a regulatory function in damping out the response to certain ligands and irreversible inhibitors. This is particularly true for immobilized (membrane bound) enzymes where the local substrate and/or inhibitor concentrations depend on influx in crowded organellar systems, e.g. cholinergic synaptic clefts. Therefore, physiological or toxicological relevance of the hysteretic behavior and damped oscillations in ChE-catalyzed reactions and inhibition cannot be ruled out.
High-efficiency multijunction laser power converters are demonstrated for low temperature applications with an optical input at 808 nm. The photovoltaic power converting III-V semiconductor devices ...are designed with GaAs absorbing layers, here with 5 thin subcells (PT5), connected by transparent tunnel junctions. Unprecedented conversion efficiencies of up to 74.7% are measured at temperatures around 150 K. At temperatures around 77 K, a remarkably low bandgap offset value of Woc = 71 mV is obtained at an optical input intensity of ~7 W/cm2. At 77 K, the PT5 retains an efficiency of 65% with up to 0.3 W of converted output power.
Experiments have been performed evidencing significant stimulated Raman sidescattering (SRS) at large angles from the density gradient. This was achieved in long scale-length high-temperature plasmas ...in which two beams couple to the same scattered electromagnetic wave further demonstrating for the first time this multiple-beam collective SRS interaction. The collective nature of the coupling and the amplification at large angles from the density gradient increase the global SRS losses and produce light scattered in novel directions out of the planes of incidence of the beams. These findings obtained in plasmas conditions relevant of inertial confinement fusion experiments similarly apply to the more complex geometry of these experiments where anomalously large levels of SRS were measured.
IntAct is an open-source, open data molecular interaction database populated by data either curated from the literature or from direct data depositions. Two levels of curation are now available ...within the database, with both IMEx-level annotation and less detailed MIMIx-compatible entries currently supported. As from September 2011, IntAct contains approximately 275 000 curated binary interaction evidences from over 5000 publications. The IntAct website has been improved to enhance the search process and in particular the graphical display of the results. New data download formats are also available, which will facilitate the inclusion of IntAct's data in the Semantic Web. IntAct is an active contributor to the IMEx consortium (http://www.imexconsortium.org). IntAct source code and data are freely available at http://www.ebi.ac.uk/intact.
Two main metrics are usually employed to assess the quality of medical ultrasound (US) images, namely the contrast and the spatial resolution. A number of imaging algorithms have been proposed to ...improve one of those metrics, often at the expense of the other one. This paper presents the application of a correlation-based ultrasound imaging method, called Excitelet, to medical US imaging applications and the inclusion of a new Phase Coherence (PC) metric within its formalism. The main idea behind this algorithm, originally developed and validated for Non-Destructive Testing (NDT) applications, is to correlate a reference signal database with the measured signals acquired from a transducer array. In this paper, it is shown that improved lateral resolutions and a reduction of imaging artifacts are obtained over the Synthetic Aperture Focusing Technique (SAFT) when using Excitelet in conjunction with a PC filter. This novel method shows potential for the imaging of specular reflectors, such as invasive surgical tools. Numerical and experimental results presented in this paper demonstrate the benefit, in terms of contrast and resolution, of using the Excitelet method combined with PC for the imaging of strong reflectors.
•A new phase coherence filter is presented for improved contrasts.•The correlation-based algorithm Excitelet is applied to ultrasound medical imaging.•Excitelet outperforms the synthetic aperture method in terms of resolutions.•The correlation-based method is efficient for the imaging of surgical tools.
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