Search results for "chemistry [Arsenates]"
showing 10 items of 2372 documents
A method for measuring wetting and swelling of bentonite using X-ray imaging
2022
A non-invasive method based on X-ray imaging for measuring deformation and water transport in wetting and swelling bentonite samples is introduced. Sequential X-ray images taken of the samples were used to calculate the attenuation coefficient and deformation. These results, together with careful calibration, allowed finding the dry density and water content distributions and their temporal evolution in the wetting and swelling samples. A specific correction technique, based on regularly taking reference X-ray images of aluminum plates of varying thickness, was developed and used to take into account X-ray beam instabilities and thus to improve the accuracy of density analysis. Large deform…
Psychrophiles: A source of cold-adapted enzymes for energy efficient biotechnological industrial processes
2021
Biocatalysts are the backbone of bioprocessing industries that are going through a phase of transition with reference to the requirement of extraordinary enzymes for various biochemical processes. This transition is well reported and documented by various researchers through elucidation of different features and applications of mesophilic and thermophilic enzymes. However, there is little information available about psychrophilic enzymes and their involvement in industrial processes. Therefore, understanding the features and functions of psychrophilic enzymes could suggest some of their novel applications in various industries such as food, agriculture, chemicals, pharmaceuticals, and waste…
Stress sensitivity of stylolite morphology
2009
International audience; Stylolites are rough surfaces that form by localized stress-induced dissolution. Using a set of limestone rock samples collected at different depths from a vertical section in Cirque de Navacelles (France), we study the influence of the lithostatic stress on the stylolites morphology on the basis of a recent morphogenesis model. We measured the roughness of a series of bedding-parallel stylolites and show that their morphology exhibits a scaling invariance with two self-affine scaling regimes separated by a crossover-length (L) at the millimeter scale consistent with previous studies. The importance of the present contribution is to estimate the stylolite formation s…
Zinc Adsorption by Activated Carbon Prepared from Lignocellulosic Waste Biomass
2019
Sawdust was used as a precursor for the production of biomass-based activated carbon. Carbonization and activation are single-stage processes, and steam was used as a physical activation agent at 800 °
On the use of composite indicators for mobile communications network management in smart sustainable cities
2020
Beyond 5G networks will be fundamental towards enabling sustainable mobile communication networks. One of the most challenging scenarios will be met in ultra-dense networks that are deployed in densely populated areas. In this particular case, mobile network operators should benefit from new assessment metrics and data science tools to ensure an effective management of their networks. In fact, incorporating architectures allowing a cognitive network management framework could simplify processes and enhance the network&rsquo
Enhancing the Iterative Smoothed Particle Hydrodynamics Method
2021
Motivated by recent research on the iterative approach proposed for the smoothed particle hydrodynamics (ISPH) method, some ideas to improve the process are introduced. The standard procedure is enhanced iterating on the residuals preserving the matrix-free nature of the process. The method is appealing providing reasonable results with disordered data distribution too and no kernel variations are needed in the approximation. This work moves forward with a novel formulation requiring a lower number of iterations to reach a desired accuracy. The computational procedure is described and some results are introduced to appreciate the proposed formulation.
Friction and Heat Transfer in Membrane Distillation Channels: An Experimental Study on Conventional and Novel Spacers
2022
The results of an experimental investigation on pressure drop and heat transfer in spacer-filled plane channels, which are representative of Membrane Distillation units, are presented and discussed. Local and mean heat transfer coefficients were obtained by using Thermochromic Liquid Crystals and Digital Image Processing. The performances of a novel spacer geometry, consisting of spheres that are connected by cylindrical rods, and are hereafter named spheres spacers, were compared with those of more conventional woven and overlapped spacers at equal values of the Reynolds number Re (in the range ~150 to ~2500), the pitch-to-channel height ratio, the flow attack angle and the thermal boundar…
Heterogeneous photocatalysis: guidelines on experimental setup, catalyst characterization, interpretation, and assessment of reactivity
2019
Soon after the publication of the first pioneering works on heterogeneous photocatalysis, the number of papers on this topic continuously increased. This intriguing field of research is very complex as it endows with an interdisciplinary overview that involves different aspects of chemistry, physics, material and environmental sciences. Even if photocatalytic applications in real processes are often difficult to be implemented and scaled-up, investigations at laboratory scale are easy to be performed, and in some cases they may give rise to misconceptions. For this reason, the present work aims to sum up most of the common experimental techniques and procedures generally used in heterogeneo…
In situ measurements of background aerosol and subvisible cirrus in the tropical tropopause region
2002
[1] In situ aerosol measurements were performed in the Indian Ocean Intertropical Convergence Zone (ITCZ) region during the Airborne Polar Experiment-Third European Stratospheric Experiment on Ozone (APE-THESEO) field campaign based in Mahe, Seychelles between 24 February and 6 March 1999. These are measurements of particle size distributions with a laser optical particle counter of the Forward Scattering Spectrometer Probe (FSSP)-300 type operated on the Russian M-55 high-altitude research aircraft Geophysica in the tropical upper troposphere and lower stratosphere up to altitudes of 21 km. On 24 and 27 February 1999, ultrathin layers of cirrus clouds were penetrated by Geophysica directly…
High-Performance Lead-Acid Batteries Enabled by Pb and PbO2 Nanostructured Electrodes: Effect of Operating Temperature
2021
Lead-acid batteries are now widely used for energy storage, as result of an established and reliable technology. In the last decade, several studies have been carried out to improve the performance of this type of batteries, with the main objective to replace the conventional plates with innovative electrodes with improved stability, increased capacity and a larger active surface. Such studies ultimately aim to improve the kinetics of electrochemical conversion reactions at the electrode-solution interface and to guarantee a good electrical continuity during the repeated charge/discharge cycles. To achieve these objectives, our contribution focuses on the employment of nanostructured electr…