Développement de la méthode de Monte Carlo pour le calcul des interactions et du transport électrique dans les semi-conducteurs ternaires

Development of the Monte Carlo method for the calculation of theinteractions and electric transport in the ternary semiconductorsIn this paper; we show the interest of the heterostructures initially, then the need for using a numerical method and in particular that of Monte Carlo, to calculate electric transport in the semiconductors. We justify also the composition of our ternary semiconductor AlxGa1-xAs. Afterwards; we give the principle and the implementation of the method which we adapted to our case, while trying to approach us reality. We apply finally this method to calculate the interactions and electric transport in our compound

Experimental Animal Models in Periodontology: A Review

In periodontal research, animal studies are complementary to in vitro experiments prior to testing new treatments. Animal models should make possible the validation of hypotheses and prove the safety and efficacy of new regenerating approaches using biomaterials, growth factors or stem cells. A review of the literature was carried out by using electronic databases (PubMed, ISI Web of Science). Numerous animal models in different species such as rats, hamsters, rabbits, ferrets, canines and primates have been used for modeling human periodontal diseases and treatments. However, both the anatomy and physiopathology of animals are different from those of humans, making difficult the evaluation of new therapies. Experimental models have been developed in order to reproduce major periodontal diseases (gingivitis, periodontitis), their pathogenesis and to investigate new surgical techniques. The aim of this review is to define the most pertinent animal models for periodontal research depending on the hypothesis and expected results

Ocena współczynnika odpływu za pomocą metody hierarchicznej analizy problemów decyzyjnych

The runoff coefficient (RC) is a parameter that is very often used in surface hydrology in order to characterize the drainage capacity of a watershed. The traditional estimate of this coefficient is often made from abacuses based on 2 or 3 parameters to the maximum. In this work, three numerical models are presented. Two models are based on experimental work. The first one is based on three criteria, namely the vegetation cover, the type of soil, and the slope. The second one considers the size of the watershed, the maximum daily rainfall and the type of soil. In practice, it is not easy to estimate the coefficient of runoff by simultaneously considering the influence of several criteria. In order to overcome this problem, a third model is developed and presented; it allows capitalizing the information from the first two models mentioned above. The objective of the present work is to be able to verify the comparability of these criteria and to assess the relative importance of each of them.Współczynnik odpływu (RC) jest parametrem często używanym w hydrologii wód powierzchniowych w celu charakterystyki zdolności drenarskiej zlewni. Tradycyjnie ocenę tego współczynnika wykonuje się za pomocą obliczeń bazujących maksymalnie na 2–3 parametrach. W niniejszej pracy przedstawiono trzy modele numeryczne. Dwa z nich oparte są na badaniach eksperymentalnych. Pierwszy bazuje na trzech kryteriach: pokrycie roślinnością, typ gleby i nachylenie terenu. Drugi uwzględnia rozmiar zlewni, maksymalny opad dobowy i typ gleby. W praktyce nie jest łatwo ocenić współczynnik odpływu przez uwzględnienie wpływu kilku kryteriów równocześnie. Aby rozwiązać ten problem, zbudowano i przedstawiono trzeci model. Umożliwia on połączenie informacji z dwóch wyżej wymienionych modeli. Celem pracy jest umożliwienie weryfikacji porównywalności kryteriów i dokonanie oceny względnego znaczenia każdego z nich

Design of a novel photonic crystal 1.31/1.55 µm bi-band filter for near infrared application

A novel design of a double selective filter for integrated optics in two-dimensional photonic crystals operating at a wavelength of 1.31 and 1.55 µm is proposed in this paper. We focus particularly on filters transmission and selectivity enhancement. The two-dimensional photonic crystals filters are simulated by using a combination of three cascaded waveguides; these later are conceived by one missing row and with different rods radii for efficient filtering purpose. The properties of these photonic crystal structures are numerically investigated by using the two-dimensional finite-difference time-domain method and the numerical results are given for incident light wave having transverse electrical polarization. A final synthesized filter topology is presented and the maximum of transmission is found around 70% and 60% localized respectively near 1.31 and 1.55 µm wavelengths

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

Adsorption and corrosion inhibition of new synthesized Pyridazinium-Based Ionic Liquid on Carbon Steel in 0.5 M H2S04

The corrosion inhibition properties of 1-(2-ethoxy-2-oxoethyl) pyridazinium chloride (EOPC) on carbon steel (CS) in sulfuric acid (0.5 M H2SO4) solution has been examined and characterized by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The experimental results reveal that the compound has a good inhibiting effect on the metal tested in 0.5M H2SO4 solution. The inhibition efficiency for this compound studied increased with the increase in the inhibitor concentrations to attain 91.67 % at the 10-3 M of EOPC. Polarization curves showed that EOPC acted as a mixed-type inhibitor in sulfuric acid. EIS results show that the change in the impedance parameters (Rt and Cdl) with concentration of EOPC is indicative of the adsorption of molecules leading to the formation of a protective layer on the surface of carbon steel. The effect of the temperature on the corrosion behavior with addition of 10-3M of the inhibitor was studied in the temperature range 298-328 K, and the thermodynamic parameters were determined and discussed. The adsorption of this compound on CS surface obeys Langmuir's adsorption isotherm

Molecular Structure, Phase Composition, Melting Behavior, and Chain Entanglements in the Amorphous Phase of High-Density Polyethylenes

A methodology for estimating the entanglement density in the amorphous phase of semicrystalline polyolefins was developed. The method is based on the analysis of the density of physical network junctions in the amorphous phase by 1H NMR T2 relaxation experiments. The density of the entanglement network was estimated for melt- and high-pressure-crystallized high-density polyethylenes (HDPEs) at temperatures close to and gradually approaching melting. Its value is lower for high-pressure-crystallized HDPE than for the same melt-crystallized polymer. The network of entanglements is characterized by the fraction of entangled network chains, the weight-average molecular weight of the network chains between apparent chain entanglements, Me, and the volume average density of apparent chain entanglements. The entanglement network was studied in a series of low- and high-molecular-weight HDPEs and bimodal HDPE samples with different molecular weight characteristics and densities controlled by different contents of the 1-butene comonomer. It turns out that the molecular weight characteristics of the HDPEs influence the entanglement network. The fraction of network chains and the average density of apparent chain entanglements decrease with decreasing molecular weight Mn due to the “dilution” effect caused by disentangled chain-end segments increasing the Me. The current methodology is of interest for studying the effect of crystallization conditions, molecular structures, and short-chain branches on phase composition, melting behavior, and chain entanglements in the amorphous phase of polyolefins. The method allows estimation of the fraction of network chains, which potentially can form tie-chain segments during deformation. The effect of short-chain branches and molecular weight characteristics on the creep response of polyolefins is discussed