Elaboration and Characterization of Recycled PP/Clay Nanocomposites

In this paper, the elaboration and characterization of recycled polypropylene/Tunisian clay nanocomposites has been investigated. When recycled, polypropylene polymer is degraded and has poorer mechanical and rheological properties. To overcome this problem, we proposed to incorporate Tunisian clay nanoparticles in recycled polypropylene (rPP) matrix. The incorporation of Tunisian clay was performed in molten state using maleic anhydride grafted polypropylene (PP-g-MA) as compatibilizer. The dispersion of clay in rPP polymer was evaluated by scanning electron microscopy and Fourier transformed infrared spectroscopy. Thus, Tunisian clay was more dispersed in nanocomposites with the increase of Tunisian clay loading. In dead, the incorporation of silicate layers gave rise to a considerable increase of the static viscosity demonstrating the reinforcing effect of Tunisian clay nanofillers on rPP matrix. However, the increasing trend of morphological and rheological properties is lower when the clay content exceeds 5%

Binding adaptation of GS 441524 diversifies macro domains and downregulate SARS CoV 2 de MARylation capacity

Viral infection in cells triggers a cascade of molecular defense mechanisms to maintain host cell homoeostasis. One of these mechanisms is ADP ribosylation, a fundamental post translational modification PTM characterized by the addition of ADP ribose ADPr on substrates. Poly ADP ribose polymerases PARPs are implicated in this process and they perform ADP ribosylation on host and pathogen proteins. Some viral families contain structural motifs that can reverse this PTM. These motifs known as macro domains MDs are evolutionarily conserved protein domains found in all kingdoms of life. They are divided in different classes with the viral belonging to Macro D type class because of their properties to recognize and revert the ADP ribosylation. Viral MDs are potential pharmaceutical targets, capable to counteract host immune response. Sequence and structural homology between viral and human MDs are an impediment for the development of new active compounds against their function. Remdesivir, is a drug administrated in viral infections inhibiting viral replication through RNA dependent RNA polymerase RdRp . Herein, GS 441524, the active metabolite of the remdesivir, is tested as a hydrolase inhibitor for several viral MDs and for its binding to human homologs found in PARPs. This study presents biochemical and biophysical studies, which indicate that GS 441524 selectively modifies SARS CoV 2 MD de MARylation activity, while it does not interact with hPARP14 MD2 and hPARP15 MD2. The structural investigation of MD GS 441524 complexes, using solution NMR and X ray crystallography, discloses the impact of certain amino acids in ADPr binding cavity suggesting that F360 and its adjacent residues tune the selective binding of the inhibitor to SARS CoV 2 M

Rain concentration and sheltering effect of solar panels on cultivated plots

Agrivoltaism is the association of agricultural and photovoltaic energy production on the same land area, coping with the increasing pressure on land use and water resources while delivering clean and renewable energy. However, the solar panels located above the cultivated plots also have a seemingly yes unexplored effect on rain redistribution, sheltering large parts of the plot but redirecting concentrated fluxes on a few locations. The spatial heterogeneity in water amounts observed on the ground is high in the general case; its dynamical patterns are directly attributable to the mobile panels through their geometrical characteristics (dimensions, height, coverage percentage) and the strategies selected to rotate them around their support tube. A coefficient of variation is used to measure this spatial heterogeneity and to compare it with the coefficient of uniformity that classically describes the efficiency of irrigation systems. A rain redistribution model (AVrain) was derived from literature elements and theoretical grounds and then validated from experiments in both field and controlled conditions. AVrain simulates the effective rain amounts on the plot from a few forcing data (rainfall, wind velocity and direction) and thus allows real-time strategies that consist in operating the panels so as to limit the rain interception mainly responsible for the spatial heterogeneities. Such avoidance strategies resulted in a sharp decrease in the coefficient of variation, e.g. 0.22 vs. 2.13 for panels held flat during one of the monitored rain events, which is a fairly good uniformity score for irrigation specialists. Finally, the water amounts predicted by AVrain were used as inputs to Hydrus-2D for a brief exploratory study on the impact of the presence of solar panels on rain redistribution at shallow depths within soils: similar, more diffuse patterns were simulated and were coherent with field measurements

Progress in Polyethylene Terephthalate Recycling

In the last decade, an increasing interest has been focused on the recycling of plastic wastes, especially on the polyethylene terephthalate (PET). PET polymer is already being recycled and numerous applications for recycled polyesters can be explored depending on the properties of the resin. However, the common problem faced during processing of recycled PET is degradation. Thus, many solutions have been proposed in literature to undermine this problem. This chapter presents a background of the current state of knowledge with respect to PET recycling. In the first section, a brief theoretical background is presented about virgin PET synthesis, thermal transitions, processing and applications. The second section deals with the PET recycling process with a focus on contaminations and ways to increase the molecular weight of recycled PET (RPET). It serves as an introduction to Section Three where our process to improve the RPET properties is described. Finally, Section Four covers the effect of blending virgin PET (VPET) with recycled PET on thermal and rheological behavior

Evaluation of FSO link throughput in Qatar

Despite the vibrant advantages of Free Space Optics (FSO) technology and the variety of its applications, its widespread adoption has been hampered by rather disappointing link reliability for long-range links due to atmospheric turbulence-induced fading and sensitivity to detrimental climate conditions. A major challenge of such hybrid systems is to provide a strong backup system with soft-switching capabilities when the FSO link becomes down. The specific objective of this work is to study for the first time in Qatar and the Gulf Cooperation Council (GCC) the link capacity, link availability, and link outage of an FSO system with Radio Frequency (RF) back up (i.e. hybrid FSO/RF). In order to analyze the two transport media, we have designed a network sniffer application in Linux and embedded it in FPGA. We have installed new FSO/RF terminals and configure and align them successively. In the reporting period, we carry out measurements and relate them to real-Time weather conditions. The relative humidity, which is due to high temperature and does not generally form fogs, was found to be the main factor degrading the FSO link throughput rather than the fog as reported in previous studies in Europe and North America.Scopu

DIFFUSION AND NOISE IN GAAS MATERIAL AND DEVICES

International audienceThe variation of the diffusion coefficent D(E) versus the electric field strength E, is determined at 300 K in n-type GaAs (N(D) = 3 x 10(-17) cm-3), using pulsed high-frequency noise measurements. D(E) is found to increase slightly at low field, then to decrease down to one tenth of its ohmic value near the threshold field. "Long" (greater-than-or-equal-to 4-mu-m) real n+-n-n+ Gunn diodes, with an arbitrary doping profile, can be modeled. Comparisons are made, and excellent agreement is found, between experimental and theoretical characteristics of two real diodes, with notch and with gradual doping profiles. The doping profile N(D)(x) is shown to have a considerable influence on the diode behavior, concerning the electric field profile as well as the noise characteristics. Using the impedance field method, the noise current is modeled and found to be very sensitive in the D(E) variation law, in particular in the range of 2.5-4 kV/cm. The agreement between the experimental noise and the computed noise of real diodes is found to be quite satisfactory when using D(E) determined in the present work, and important discrepancies occur when using other D(E) variations, both theoretical and experimental, found in the literature

Reinforcement of recycled PP polymers by nanoparticles incorporation

Recycling process seems to be the most efficient way to reduce ecological impacts of used polymers. Nevertheless, the properties of the recycled PP polymer are proved to be insufficient during its reuse, particularly with regard to its thermo-mechanical and rheological behaviors. The incorporation of nanoparticles as fillers into polymer matrix seems to be one of the most successful solutions to upgrade recycled PP polymer. This paper presents an overview on the application of different nanofillers such as clay, calcium carbonate (CaCO3), Silica (SiO2), Zinc Oxide (ZnO), carbon black (CB), carbon nanotubes (CNT), antioxidizers and others into recycled PP matrix. Literature works on the effects of nanofillers on obtained nanocomposites are extensively studied. The first section deals with PP recycling and its impact on thermal, mechanical and rheological properties of the polymer. Then, the second part summarizes recent studies on the effects of nanoparticles incorporation on thermo-mechanical and rheological properties of recycled PP. Finally, recyclability of PP-based nanocomposites is discussed