Anionic clays has been used in the adsorption of anionic species of toxic heavy metals, such as chromium (VI), which is considered to be a dangerous pollutant, due to its deleterious effects on human health such as epithelial irritation and cancer. In this work the removal of chromium in aqueous solutions using anionic clays with Mg/Al=7 was determined. The anionic clays were synthesized by the sol-gel method at pH 10 and 11.5, and were characterized by X-ray diffraction, thermal analysis, infrared spectroscopy and N2 adsorption Brunauer-Emmett-Teller (BET). By this method, anionic clay containing brucite was obtained. The solids exhibited meso-porosity, high surface areas and thermal stability until 500°C. The data obtained from the adsorption experiments of chromium fitted to the Langmuir adsorption isotherm model and the adsorbent capacity was determined using the Langmuir adsorption equation. The maximum chromium uptake was 45 mg of Cr/g sorbent and 43 mg Cr/g sorbent for anionic clays prepared to pH 10 and 11.5, respectively. The Cr saturation point was attained after eight minutes stirring time. According to chromium adsorption values, the solution pH does not have a significant affect on the adsorption capacity of the anionic clays.

Textile 100 % acrylic fabrics have been used in tapestry for a long time. One of the drawbacks of this type of fabrics is its great flammability. Textile fabrics are coated with flame retardant in order to reduce the flammability. We present some results concerning the use of commercial products (Flame-Out, Borax (Na2B4O5(OH)4•8H2O), and Hexametaphosphate of Sodium (Na16P14O43) as flame retardants for textile 100 % acrylic fabrics. The flame retardant capabilities, mechanical properties and structural characteristics of the textile fabrics before and after the use of these products were investigated throughout the special textile methods for inflammability and mechanical resistibility as well as infra-red spectroscopy, X-ray diffraction and scanning electronic microscopy. After the use of the flame retardants the mechanical properties of the fabrics were improved or at least remained the same as compared to fabrics without any treatment. The use of Borax / Hexametaphosphate from Sodium /Water results in the essential increase of combustion retardation time about 2 minutes as compared with 8 seconds for untreated fabrics.

Stress corrosion cracking (SCC) susceptibility of API X60 pipeline steel in a soil solution by slow strain rate tests (SSRT), and surface fracture analysis was investigated. The SSRT were performed at strain rate of 25.4 × 10-6 mm/sec in a glass autoclave containing the soil solution called NS4 with pH of 3 and 10 at room temperature and 50°C. Both anodic and cathodic polarization potentials of 200 mV referred to Ecorr was applied. The results of ratio reduction area (RRA), time to failure ratio (TFR) and elongation plastic ratio (EPR) indicate that X60 pipeline steel was susceptible to SCC at pH 3 and cathodic polarization of -200 mV at room temperature and 50°C. Scanning electron microscopy (SEM) observations of these specimens showed a brittle type of fracture with transgranular appearance. The SCC process and mechanism of X60 steel into NS4 solution was hydrogen based mechanism. With the different applied potentials the dominance of SCC process changes. At low pH the temperature effect on SCC susceptibility is more noticeable at 20°C. However at high pH this effects changes, being the steel more susceptible to SCC at 50°C.

For centuries, the manipulation of mechanical properties for the development of components has been extremely important. Its relevance is based on improving the service life in the components. The aim of some techniques that have been used is to introduce strain hardening (tensile) and a beneficial residual stress field. Nevertheless, the application of both methods is very common when the component is manufactured, but the lack of knowledge of the final physical state of the material could compromise the structural integrity of the final product. This work presents a numerical evaluation concerning the characterization of a stainless steel AISI 316L, having a homogeneous axial history and a residual stress field. The relevance of the work is focused in a new methodology that can be used to improve the mechanical resistance of the component and to arrest crack propagation. By altering the mechanical properties of the material, it could be possible to delay nucleation and interrupt the propagation of cracks. This study also shows that if the strain hardening behaviour and the introduction of the residual stress field is not done properly, it could result in a component susceptible to fail. In the same sense, bending tests are proposed to provide tensile and compressive stress profiles.

The pipelines are the main transport and distribution system of production in the oil industry, which are subject to environmental and operational conditions which are not favorable for the operation of the pipelines and sometimes represent the risk of accidents and high economic losses. The evolution of risk begins with a systematic search of possible threats to the integrity of the pipeline. The identification of potential threats should not be limited to known risk categories reviewed, but must complete the steps to find new and unique expressions of risk and the study of particular cases. Thus, the importance of a comprehensive risk assessment of the transmission pipeline is crucial. In this paper an integrity assessment for corrosion damages in pipelines was developed through a methodology based on risk analysis to estimate the propagation rate on the time, the size, location and number of damages. To perform this study a data obtained from smart pig runs and an artificial neural network (ANN) model with retro propagation was used. From the data obtained from launching smart pigs on the pipeline it was carried out the training of the neural network, later on it was applied the network previously trained to get the predictions of damages on the pipeline, considering that pipeline did not have any maintenance.

In this work we used the Fourier Transform Infrared spectroscopy and UV/Vis spectroscopy to analyze the behaviour of self-ensemble films of spiropyran when the films were irradiated by UV. In UV/Vis spectroscopy is possible observe the generation of the absorption peak, at 575 nm, associated to the merocyanine state when the ring-opening process is induced by UV light. In ATR the kinetics of the ring-opening was determinate too; following the spectra changes in real time.

A kinetic study was performed on the growth of a reaction interlayer between molten Al and carbon steel substrates at temperatures between 665 to 820°C by holding Al/flux/steel assemblies, in a tube furnace, at temperature for times up to 120 min. An Ar atmosphere and a K-Al-F based flux were used to enable spreading of molten Al on the steel substrates. Chemical and microstructural characterization of the samples revealed that the interlayer is composed of FeAl3 and Fe2Al5, being the second phase significantly thicker. The Fe2Al5 phase grows toward the steel with a tongue like morphology. Isothermal growth profiles of the reaction interlayer followed a parabolic behavior, meaning that at the beginning the reaction is very rapid and once that a continuous interlayer is formed the growth of the interlayer is controlled by interdifussion of species across the interlayer.

In this work, aluminum weld beads were deposited on aluminum plates of commercial purity (12.7 mm thick), using an ER-5356 filler wire. The aim of the experiments was to assess the effects that yield the induction of an axial magnetic field (AMF) during the application of the weld beads using the direct current gas metal arc welding process (DC-GMAW). An external power source was use to induce magnetic fields between 0 to 28 mT. The effects of the magnetic fields were assessed in terms of the macrostructural features of the deposits, morphology of the grain structure, grain size and grain size distribution in the weld metal. Macrostructural characteristics of the weld beads revealed that increasing the intensity of the magnetic induction to produce a magnetic field above 14 mT, leads to a significant loss of feeding material and there is a tendency of the deposits to increase their width and reduce penetration. Perturbation of the weld pool induced by the application of the AMF noticeably modified the grain structure in the weld metal. In particular, for the intensities of 5 and 14 mT, columnar growth was essentially non-existent. Grain size distribution plots showed, generally speaking, that the use of magnetic fields is an efficient method to produce homogeneous grain structures within the weld metal. Finite element analysis was used to explain the weld bead geometry with the intensity of the magnetic field.

The effects of waste polyethylene aggregate as admixture agent in Portland cement at different addition polyethylene/cement ratios from 0.0156 to 0.3903 were investigated. The reinforced samples were prepared according the ASTM C 150 Standard (samples of 5 × 5 × 5 cm). The reinforcing fibers were milling at a size of 1/25 in diameter, form waste and used them to evaluate the effects in mechanical properties in cement-based composites. The evaluation of polyethylene as additive was based on results of density and compression tests. The 28-day compressive strength of cement reforced with plastic waste at a replacement polyethylene/cement ratio of 0.0468 was 23.5 MPa compared to the control concrete (7.5 MPa). The density of cement replaced with polyethylene varies from 2.114 (0% polyethylene) to 1.83 g/cm3 by the influence of polyethylene.

In this work we report about the design and construction of a simple and cheap calorimeter for phase transitions monitoring using Peltier elements and based in the well known inverse (front) photopyroelectric method for thermophysical characterization of materials. We describe its application for the detection of phase transitions in chocolate samples, as an alternative, for example, to the most widely used and more expensive Differential Scanning Calorimetry technique. The manufacture of chocolate requires an understanding of the chemistry and the physical properties of the product. Thus the involved problems during the confection process are those of the so-called materials science. Among them, those related with tempering are of particular importance. Because the fats in cocoa butter experience the so-called polymorphous crystallization, the primary purpose of tempering is to assure that only the best form is present in the final product. One way to characterize this is by measurement of the temperature dependence of the thermal properties of the chocolate and the monitoring of the temperature at which phase transitions take place. We show that the photopyroelectric method, aided with Peltier cells temperature control, can be a useful choice for this purpose.

The Thermax 700 thermo gravimetric analysis (TGA) instrument is introduced for the investigation of the weight change of SAPO-34 catalyst during methanol-to-olefin (MTO) process. By the use of a special sample basket with screen bottom, the TGA instrument can be viewed as fixed-bed reactor, while the weight change of SAPO-34 during MTO reaction can be recorded online. It is noticed that the SAPO-34 catalyst experiences a procedure of dehydration as furnace temperature rises; hence the weight increase of SAPO-34 during MTO reaction should be calculated based on the weight after dehydration. It is checked that the increase of weight is mainly coke ignore of adsorbates. In the range of 648∼773K temperature and 7.08∼35.9h-1 (WHSV) space velocity, the maximum coke deposition is roughly 25% independent of reaction condition. The coke formation experiences a stage of fast increase soon after reaction initiates, while slows down apparently after 18% coke is deposited on the catalyst. Higher temperature, space velocity and methanol partial pressure accelerate the coking rate. Temperature plays an important role in the type of coke formation, which can be distinguished directly by the colour of completely deactivated catalyst. The deactivated catalyst in lower temperature experiences a weight loss with partly recovery of catalyst activity as temperature rises in the hydrothermal atmosphere. The phenomenon of weight loss with catalyst regeneration will not occur as reaction temperature decreases for deactivated catalyst, as well as the different DTA curves for coke burning, are also evidences for the different type of coke formation on SAPO-34 catalyst in different reaction temperature.

Au/TiO2 thin films have been prepared from Titanium Tetrabuthoxide-acetylacetone solution and buthanol as solvent by sol-gel and dip-coating technique. Au nanoparticles were prepared from HAuCl4 solution. The deposition of Au nanoparticles was by spray pyrolysis method. The films from the sol gel solution were heat treated at 450°C for 1 hour. The surface structures, morphology, composition and optical properties on the films were investigated by atomic force microscopy (AFM), optical microscopy (OM), X-ray Diffraction (XRD) and UV-Vis spectrometer. It was found the film consisted of anatase phase (TiO2), Au nanoparticles in the range of 50 to 100 nm, and few cracks on the surface remaining attached to the glass substrate. In this study, we measured the photocatalytic degradation of a methylene blue (MB) aqueous solution by a film prepared by the sol-gel and dip-coating methods TiO2 and Au/TiO2films prepared by spray pyrolysis method. We found that Au nanoparticles deposited on the TiO2films improved the photocatalytic activity and minor degradation time that TiO2 films.

The photoluminescence (PL) and photoluminescence temperature dependences have been studied in InAs quantum dots (QDs) embedded in the In0.15Ga1–0.15As/GaAs quantum wells (QWs) with QDs grown at different temperatures (470–535 °C). Ground state (GS) related QD PL peaks shift into the red side with increasing QD growth temperature to 510 °C and the blue shift is observed when the temperature increased to 535 °C. The temperature dependences of GS PL peak positions were fitted on the base of Varshni relation and the fitting parameters were compared with the bulk InAs and the In0.21Ga0.79As allow. This comparison has revealed that for QDs grown at 490–510 °C the PL fitting parameters are the same as for the bulk InAs crystal. The DWELL structures with QDs grown at other temperatures have fitting parameters different from the bulk InAs. Last fact testifies that in these structures the Ga/In inter-diffusion between QDs and a QW has been realized. This Ga/In intermixture can be stimulated not only by the high temperature (535 °C), but by the essential elastic stress as well in the DWELL structure with lower QD densities.