Proceedings of the 4th International Symposium on Materials and Sustainable Development

This contribution describes the strategy of a one-layer Transdermal Drug Delivery System (TDDS) device, where a hydrogel acts both as a drug delivery system and a Pressure Sensitive Adhesive (PSA), differing from the most well-known TDDS, where the device is essentially comprised of a drug reservoir with a protective outer cover, a permeable membrane, an adhesive, and a release liner.

Accordingly, we have synthesized conventional poly(acrylamide-co-hydroxyethyl methacrylate) [P(AM-HEMA)] hydrogels and nanocomposite hydrogels filled with poly(styrène-co-butyl acrylate) nanoparticles [P(AM-HEMA)-PSBuA]. PSBuA nanoparticles were synthesized by direct emulsion polymerization. P(AM-HEMA) hydrogels with HEMA content of 10 and 20 mol% and those filled with 26 wt.% of PSBuA nanoparticles were prepared by a free radical polymerization in aqueous medium using N, N’-methylene-bis-acrylamide (Bis) and potassium persulfate as cross-linking agent and initiator respectively. Hydrogels adhesive properties were evaluated when they were applied to different substrates, equivalent human skin and stainless steel, using a probe tack test. These properties were studied as functions of the chemical composition of the hydrogel and the nature of the substrate. The adhesion energy was found to be related to the chemical composition and the rheological properties of the hydrogels which were also evaluated by the determination of elastic G’ and loss G” moduli derived from oscillatory shearing measurements performed in the linear domain.

Aluminum alloys have a considerable appeal for mechanical and building designers. This characteristic lies in the mechanical and physicochemical properties of these alloys. Aluminum is often used in the anodized surface condition to impart pleasing aesthetics, higher corrosion resistance, better scratch and wear resistance, and thus an improved value of the product. Anodization is commonly produced by direct current (DC) that offers excellent protection against wear and corrosion. This work focuses on the surface condition of a 2030 aluminum alloy treated with chromium and sulfuric acid. Our goal is to understand what happens at the surface of the Al alloy after each treatment (chromic anodizing, sulfo-chromic anodizing) using a structural characterization (MEB) that will be followed by electrochemical characterization. The results obtained have shown the effectiveness of chromic anodizing, which gives rise to the formation of a thin layer and offers excellent protection against corrosion. Chromic anodic oxidation protects an aluminum part by creating a layer of alumina Al₂O₃, to give it anti-corrosion, decorative and heat resistance characteristics, as well as, any chromic acid residues do not attack the base material. This is the opposite of sulfuric acid, which makes it an excellent pretreatment for aerospace parts.

Earthquakes are among the most deadly natural events, as we have seen during the Sumatra earthquake (12/26/2004> 227 000 deaths) or the earthquake in Haiti (12/01/2010> 220 000 deaths). Even if it is not possible to predict the next seismic event, the mechanism of the earthquake is now better known. Structural damage after an earthquake is always a challenge for researchers and engineers pushing to improve and increase the capacity of structures. To this end, in this article we have proposed a new structure form cells of bees that is to say in the hexagonal form. To demonstrate the success of our proposal and its feasibility we made a comparison between two 3D digital models of hexagonal shape (cell bee) and ancient form. The results from the comparison ascertain the behavior of our model of hexagonal shape (cell bee) very effective in reducing the movements along all axes (x, y) and his more economical as ancient form. Finally, we can say that this proposed new form hexagonal structures form or as a bee cells is capable of reducing earthquake disasters.

This investigation concerns the development of two prediction fatigue life models of cross-ply laminates, made up of glass fibre and epoxy resin, loaded under flexural control load. Both models are based on the description of the load’s evolution versus the cycle number during fatigue tests by several empirical functions of logarithmic, exponential, power and linear types. The coefficients of these empirical functions depend on materials and loading conditions. Therefore, the use of such approach permits the prediction of composite fatigue life that can be made without the systematic fatigue tests which are not only costly but also time consuming, or at least reducing their number considerably. Both models allow, by a simple analytical approach, direct interpretations of physical phenomena which may intervene during tests. Furthermore, the obtained analytical results are in good agreement with the experimental ones.

The growing demand for adsorbent materials for environmental protection processes is prompting further research in the manufacture of unconventional and low cost adsorbents. In this work we have prepared a material from a natural waste namely potato peels to clean up contaminated water with a cationic dye i.e. Methylene Blue (MB). Firstly a characterization of the material was carried out in terms of bulk density, ash content, moisture content, pH and electrical conductivity. A parametric study was carried out subsequently and revealed that this adsorbent gives a better adsorption efficiency with respect to BM molecules (Tx = 95.13%) during a contact time of 45 min for a solid mass (4 g), a speed stirring (150 rpm), a solid mass/liquid volume ratio (4 g/250 mL) and an initial dye concentration (10 ppm). The modeling of the adsorption results gave an L-type isotherm with good compatibility with the Langmuir and Freundlich models.

Pure and rare earth (Ce, Er and Eu) doped ZnO aerogels have been synthesized by the sol-gel method followed by supercritical drying in isopropanol. The rare earth (RE) atomic concentration in each aerogel is fixed to 3 at. % ([RE]/[Zn] = 0.03). Zinc acetate dihydrate, rare earth nitrates (Ce, Er and Eu) and methanol were used as Zn²⁺ ions precursor, rare earth (Ce³⁺, Er³⁺ and Eu³⁺) ions source and solvent, respectively. The as-prepared aerogels were investigated using X-ray diffraction (XRD), attenuated total reflectance infrared spectroscopy (ATR-IR), UV-visible and photoluminescence (PL) spectroscopy. XRD measurements revealed that the obtained aerogels have polycrystalline ZnO hexagonal wurtzite structure and showed that the RE ions have been introduced into ZnO lattice. Also, It has been observed that Ce and Eu doping ameliorates the crystal quality and slightly changes the lattice parameters of the ZnO aerogels. ATR-IR spectra showed the high purity of the elaborated aerogels and the intensity of the absorption band related to Zn-O vibration bond is found to be dependent on the RE ions. UV-Visible spectra show that pure and RE-doped ZnO crystallites elaborated in supercritical isopropanol do not absorb in the same way due to the various stoichiometric variations of defects created during the elaboration process. It has been found that RE-doping significantly enhances the optical absorption band related to band-to-band absorption. PL spectra show that the concentration of free excitons strongly depends on the RE doping element. The PL measurements demonstrate that RE doping decreases the UV emission and increases the visible one, indicating an increase in the defects concentration localized in the band gap. The intense UV emission is found in pure ZnO aerogel, however, the visible one is found to be the largest and dominant in Ce-doped ZnO crystallites elaborated in supercritical isopropanol.

The Aluminum plates are among the most commonly used structural elements. The use of more and more important, shows the imperative need of the study of their vibratory behavior and thus becomes of great importance and helps the engineers to design better structures. Vibration analysis is an important current topic, both from an academic and an industrial point of view. The latter affects many areas, such as space technology, naval and civil engineering, automotive, aeronautics, and bridges, buildings, or nuclear engineering.

Controlling vibrations in an aluminum plate is a thorny issue that is often a problem for the researcher and the engineer. To ensure this control, the determination of the dynamic characteristics of the plates is essential. The fundamental objective of this work is to study the dynamic behavior of aluminum isotropic rectangular plates through the use of ABAQUS to predict plate characteristics in both static and dynamic states. An experimental study is carried out on the apparatus of free vibrations TM 155 to study the vibratory behavior of the plates of aluminum and consequently to predict the levels of energy of vibration as a function of the frequency. Knowledge about the maximum deformation energy level frequency of the plate will be useful for protecting and increasing the life of the plate.

During a machining operation, the cutting forces cause a relative movement between the part and the tool that melts the various cutting forces. This phenomenon, called regenerative vibration (self-sustaining), greatly affects the tool life and surface condition of the part. Traditional regenerative stability theory predicts a set of optimally stable spindle speedsat integer fractions of the natural frequency of the most flexible mode of the system. Being able to predict these phenomena therefore makes it easier to choose cutting conditions in order to improve productivity. Over the past twenty years, many theoretical models have been developed for various applications, but there have been very few studies on the particular case of three-axis milling. In this research, it is planned to study the stability of milling operations using a hemispheric tool, using differential equations of delay terms. In this article, a different model is proposed compared to the existing models for peripheral milling and for an aluminum alloy part of type 6061-T6. The model is based on the method of discretization of the lagged terms of the dynamic equation. The work was devoted first to the study of stability by the semi-discretization method, using end mill and secondly to the study of stability by the semi-discretization method, using ball-end mill.

An analytical study to predict the behaviour of clamped FGM nanoplates based on Winkler-Pasternak’s elastic foundations using hyperbolic shear deformation theory. non-local elasticity theory is used to introduce the small-scale effect. This model has a forward displacement field which includes the effect of transverse shear deformation without using shear correction factors. The winkler-Pasternak medium is introduced by considering the damping effect of the foundation model. It’s modeled by the linear Winkler coefficient and the Pasternak foundation coefficient (shear). The influences of many parameters such as the non-local parameter, the geometric ratio, the Winkler-Pasternak coefficients, the damping parameter and the mode numbers on the vibrational response are studied and discussed.

Hydrogels are a scaffold material suitable for a variety of tissue engineering applications. The combination of anhydrous octenyl succinic starch (starch OSA) with gelatin (class a), leads to the formation of a soluble complex, whose physicochemical conditions namely the molar ratio, the pH and the ionic strength were optimized by modeling response surfaces. The rheological analysis of the systems showed that the behavior was non-Newtonian and could be modeled by the Carreau model. Exploration of the RSM model of resting viscosity η0, loss angle, turbidity, and phase separation was used to determine the iso-response contours and to identify areas in which gels were obtained without recording a phase separation.

According to the mathematical models generated by this method, an optimal formulation of ratio Z = 0.3 and pH = 6 and CNaCl = 0.01 M was identified, characterized by FTIR which demonstrated the formation of the complex, by the appearance of the band at 1545 cm−1, by electrostatic interactions. The rheological characterization in oscillatory mode shows a decrease in conservation modulus G′ and the increase of the helix-pelota transition temperature of the gelatin from 37 °C to 48 °C.

The reinforcement of materials by nanoparticles has been widely studied and applied in many fields of engineering due to their unique surface effects, chemical activity and their particular physical properties. The aim of this study is to improve the mechanical properties of Kevlar^®29, by the impregnation of the later, with various weight percentages of colloidal silica-carbon nanotubes. Firstly, the colloidal solutions of silica/CNTs are prepared using LUDOX HS40 suspension mixed with three weight fractions (50, 60 and 70%) of silica. Herein, 0.02% w of CNTs dispersed in ethylene glycol (50, 40 and 30% respectively) and added to the prepared mixtures. Subsequently, the prepared solutions are used to impregnate the Kevlar using a deep flask. The morphology of the impregnated Kevlar with silica (S) and multiwall carbon nanotubes (MWCNT) are characterized by scanning electron microscopy (SEM) and the mechanical properties are highlighted using uniaxial tensile test. The observed morphology using SEM characterization gives rise to a good dispersion of silica particles at the surface of Kevlar fibers without any significant agglomeration. The tensile test results show a large improvement in mechanical properties of the impregnated Kevlar with colloidal solutions containing less than 60% of silica. Therefore, a sensitive decrease is observed above this ratio. The nanoparticles proportion affect directly the different properties of the studied materials. Hence, the rate of nanomaterials should be optimized in order to ensure optimal properties at low cost.

Nowadays, the world is facing a crisis in terms of renewable resources and a growing carbon footprint. For these reasons, the world is starting to use natural fibres as reinforcement in composite materials in various applications because of their many advantages, including their low cost, lightness and eco-friendly products, compared to synthetic ones. The aim of this paper is to study the possibility of jute fibre yarns as reinforcement in bio-composites materials for industrial application. To use these lignocellulosic fibres, it is necessary to investigate their chemical composition and mechanical properties. The jute fibre yarns investigated are constituted from three yarns twisted with a certain angle and their diameter was determined using an optical microscope. The functional groups of the jute fibres yarns were studied by Fourier Transform InfraRed spectroscopy (FTIR) and their static tensile strength and strain at failure and Young’s modulus were determined for 30 tests carried out using tensile tests machine having a capacity of 2.5 kN. In order to evaluate their mechanical properties and in view of their dispersions, a statistical analysis of the obtained experimental data was performed using two and three parameters Weibull method. The results of the jute fibre yarns were compared with house found in the literature.

Silica glass samples containing GdBO₃/Ce³⁺ nanoclusters were prepared by sol gel process. The effect of thermal treatment on the structural and optical properties was investigated. From DSC and XRD analysis, it was found that the GdBO₃ hexagonal vaterite phase crystallizes inside the silica glass above 700 ℃. The average crystallites size ranges between 20 to 50 nm when the temperature increases from 800 ℃ to 1000 ℃. TEM-EDS analysis evidenced the presence of GdBO₃:Ce³⁺ nanoclusters inside the silica matrix. Fourier transform infrared spectroscopy (FTIR) shows the presence of silica and borate linkages with significant changes in the intensity when the temperature increases from 500 ℃ to 1000 ℃. Finally, photoluminescence measurements showed that the sample heat treated at 1000 ℃ presents the maximum photoluminescence intensity assigned to the 5d 4f transition of Ce³⁺ ions.

In this paper, the high temperature magnetic properties of Dy₃Fe₅O₁₂ (DyIG) spherical single crystals are revisited by means of two types of magnetization measurements in D.C. magnetic fields. At first, isothermal magnetizations are performed in the range 125–300 K as a function of the internal field H up to 30 kOe applied in the case of the freely rotating sample and along the <111>(easy), <110>(intermediate), and <100>(hard) axes of magnetization. Close to the magnetic compensation temperature T_comp = 218.40 K, the M_T(H) curves associated to the three axes show no detectable anomaly, behave as the straight lines passing through the origin and the phases are canted. Far away T_comp, critical fields H_C1 less than 3 kOe appear for the non easy axes and the phases are canted for H < H_C1. For H > H_C1, the phases become collinear and the curves rejoin the associated one along <111> which reaches saturation for H ~ 300 Oe. There is no effect of the anisotropy in the determination of both spontaneous magnetization and paraprocess susceptibility. Secondly, isofield magnetizations are recorded at fixed external H_ex = 30 kOe, while T is varied by steps in the range 205–230 K. The derivatives of the M_Hex(T) curves are used to assign differently the transitions which are observed at critical temperatures T_C2 between one canted phase and two inverse collinear phases on each side of T_comp. Based on the Néel’s theory and beyond the Pauthenet’s method, molecular field coefficients of the interactions between Fe³⁺ and Dy³⁺ ions and within the Dy³⁺ ions at T_comp are found and the question about their discontinuities is discussed with previous results.

The objective of this work is to present a model of a High Pressure turbine blade, made of monocrystalline superalloy based on Nickel. Their leading edge can constitute privileged sites of damage and initiation of cracks which it is essential to take into account in the dimensioning of the blades of turbines. This work consisted, in a first time to make a theoretical study, the turbine blade is modeled like a beam of Timoshenko in rotation, a model of growth of damage for cycles of fatigue is developed using an approach of the mechanical damage continues. The latter is integrated with the dawn model. We made a numerical approach to study the effect of the growth of the damage on the rotating frequencies, and the effect of the number of cycles on the rigidity. Secondly, a numerical simulation of the crack propagation and the influence of vibrations on the blade is presented. Finally, an experiment on the initiation and micro-propagation of a crack is carried out. This made it possible to highlight the mechanical damage and the determination of the predictive lifespan of dawn.

In this work, ZnO-Ag-Mg layers were developed by thermal evaporation (at high temperature and very low pressure) of powder mixtures of zinc oxide, magnesium and silver with a respective mass percentages (80-10-10)%. The deposited layers on glass substrate were investigated with respect to effect of annealing temperature after deposition on the evolution of structural, optical, electrical and mechanical properties of the layers was investigated. It has been shown that after annealing at 300°C, zinc oxide (ZnO) begins to crystallize with hexagonal wurtzite structure which increases the material’s cristallinity with annealing temperature. The transmittance of the layers increases with temperature to a maximum of 75% while a change of the electrical properties from a conductive layer with 14.29 Ω of resistance value towards a semiconductor layer with resistances around 225 kΩ. Also, it was noticed that the resistance to plastic deformation (Hardness) of the layers does not respect the hall-Petch rule due to very small grain size of less than 100 nm.

In the present work, zinc oxide (ZnO) thin films were deposited at the same time by Radio Frequency (RF) magnetron sputtering technique on glass, quartz and silica-on-silicon (SiO₂/Si) substrates. The effect of substrate type on the microstructure, surface morphology, optical and luminescence properties inspected by X-ray diffraction (XRD), scanning electronic microscopy (SEM), atomic force microscopy (AFM), ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopies. XRD patterns illustrates that all prepared films crystallized in a hexagonal wurtzite structure with a (002) preferential orientation. The film deposited on SiO₂/Si substrate exhibit better crystalline quality and higher c-axis orientation. SEM and AFM images demonstrate that grain size, surface morphology and roughness of the films are substrate type dependent. A smoothest surface morphology with the smallest root-mean-square roughness (R_rms) value around 2.00 nm is obtained for the ZnO film prepared on quartz substrate. UV-Vis measurements reveal that ZnO thin film deposited on quartz substrate is highly transparent, in the visible region, with more than 84% average optical transmittance. However, a decrease in the average transmittance (81.26%) is observed for the film prepared on glass substrate. Moreover, the values of optical band gap (Eg) are found to be 3.23 and 3.24 eV for ZnO films prepared on glass and quartz substrates, respectively. Room temperature PL spectra of ZnO films grown on glass and quartz substrates show intense UV emission as well as two main weak bands centered at blue and red regions. However, the film prepared on SiO₂/Si substrate exhibit very weak emission comprising UV and several visible bands.

In the present paper, the higher order shear deformation theory is used to analyze the natural frequencies of simply supported functionally graded plate composed of a mixture of Titanium (Ti-6Al-4 V) and zirconia (ZrO₂) resting on elastic foundation. This theory accounts for adequate distribution of the transverse shear strains in the thickness of the plate and satisfies the traction free boundary conditions on the top and bottom surface of the plates, thus a shear correction factor is not required. The material properties change within the plate thickness according to the power law distribution of the volume fraction of the constituents (Titanium and zirconia). The equations of motion are derived employing the principle of Hamilton. Navier type solutions are proposed to obtain the natural frequencies of functionally graded plate and efficiency of the theory is ensured by comparing the results with the existing results. Numerical results are computed to examine the effects of different geometrical parameters such the power-law index, aspect ratio, elastic foundation parameters, and side-to-thickness ratio, on the natural frequencies of simply supported functionally graded plate. It can be concluded that the presence of the elastic foundation increases the non dimensional natural frequencies. It can be found also that the normalized natural frequencies of the plate decrease with increasing the volume fraction exponent and slenderness ratio.

Structural properties of BaTiO₃, CaTiO₃ and Ba_0.85Ca_0.15Ti_0.9 Zr_0.1O₃ prepared by conventional solid state reaction technique, at different calcinations temperatures 1100, 1150 and 1280 °C and sintering temperatures (1200 and 1300 °C) are studied. These compositions were selected because of their interesting piezoelectric properties. To follow the decomposition process of the precursor, a differential thermal analysis coupled with thermogravimetric analysis (ATG-ATD) was performed. Structural parameters are analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The obtained results showed clearly the synthesis of the perovskite phase. The diffractogram illustrates that BCTZ symmetry is both cubic with a Pm-3 m space group and orthorhombic with a R3m space group, the calculated phase rates are respectively 10% and 90%. The results allowed us to specify the effect of sintering temperatures on the structural properties of ceramics.

ZnO films deposited on silicon porous substrates (PS) were prepared by electro-deposition anodization on (100) silicon wafer. This ZnO/PS structure combines substrates having specific structural and optical properties (IR emission), with nano-composites of ZnO potentially interesting due to their functional properties (UV emission) to be integrated as constitutive elements of devices in various optoelectronic applications mainly in blue light emitters. The structural properties characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and the optical properties as the photoluminescence and the reflectance were investigated here by FT-IR spectrometry measurements and had been clearly interpreted. Our ZnO nanocomposites were successfully deposited on PS substrates. These nanostructures were prepared by electrodeposition technique using ZnCl₂ and the KCl under optimized conditions. This technique has some advantages compared to the physical deposition techniques. By this combine the photoluminescence (PL) of ZnO/PS increased and covered the most of the visible spectra. SEM images shows clearly that the ZnO particles entered in the pores of porous silicon despite the fact that few pores of PS were not covered completely by the ZnO particles. In other words, with the high porosity and the low dimension of the PS layer structure may be increase the photoluminescence (PL). With this combined structure, the blue shift in the PL peak is possible and easy to obtain (467 nm). The blue shift in the PL peak is possible and easy to obtain.

Corrosion is a major problem in the industry that could pose damage to the environment and the economy. In this context, the monitoring of corrosion is essential. Several methods of corrosion monitoring have been proposed in recent decades such as the electrical resistance technique. This technique is used to measure the weight loss of a thin metal layer resulting from a change in electrical resistance. Our objective is to elaborate a sensor based on the electrical change of a thin layer of copper that allows following the corrosion according to the principle of the electrical resistance method. This last approach allowed us to follow the corrosiveness of aggressive environments such as HCl, H₂SO₄ and NaCl depending on the temperature. The results of studies obtained by an electrochemical characterization (OCP, EIS, Tafel), electrical and optical characterization show that the electrical resistance sensor is a reliable and promising tool that not only applies to corrosion monitoring of metallic materials but also to classify environments according to their corrosivity.

The assurance of the bacteria survival is the key of the protective technique aiming to alleviate the bacteria resistance under digestive hostilities. Among the methods of protection, microencapsulation of cells in various biomaterials has given convincing results. We tried to exploit for the first time the emulsifying properties of carob galactomannans reinforced herein by the sodium alginate gel in the microencapsulation of beneficial bacteria. On the other hand, we explored the benefits of this protective technique upon the expression of the bacterial ability to uptake cholesterol, in complement to our previously published results. The present study aimed to develop a new mixed gel containing calcium alginate and galactomannans extracted from the Algerian carob seeds endospermes, for the microencapsulation of the human strain of Lactobacillus rhamnosus LbRE-LSAS; compared with the probiotic strain of Bifidobacterium animalis subsp. lactis Bb12. Influence of microencapsulation was tested under simulated digestive environment to verify if both bacteria preserve their viability and their cholesterol assimilation ability. High viable loads of encapsulated LbRE-LSAS and Bb12 were registered (6.97 and 8.66 of 10 Log CFU g⁻¹, respectively). Conversely, the free cell levels strongly (P < 0.05) decreased during exposure to the digestive simulated conditions. According to our results, the new formed gel permits to improve 1.8-fold on average the cholesterol assimilation ability of probiotic bacteria. We underlined the possible use of carob galactomannans-Ca-alginate beads as alternative healthy solution in protecting beneficial bacteria under gastro-intestinal conditions, and by the way, lowering the serum cholesterol level in the host.