BaAl2Si2O8 and SrAl2Si2O8 were synthesized by solid-state reaction of stoichiometric mixtures of either BaCO3 or SrCO3 with coal fly ash and Al2O3. The mixtures were mechanically activated in an attrition mill for up to 12 h and then reaction-sintered at 900-1300 °C, aiming to promote the formation of BaAl2Si2O8 and SrAl2Si2O8 as well as the conversion from their hexagonal (Hexacelsian) into their monoclinic (Celsian) forms, which is associated with improved mechanical properties in the sintered materials. Especially in the case of SrAl2Si2O8, the formation of Celsian was favored at relatively low sintering temperatures by increasing milling time. Although only the SrAl2Si2O8 composition was fully converted into Celsian, the Hexacelsian to Celsian conversions obtained for the mechanically-activated BaAl2Si2O8 composition were significantly higher than those previously reported in the literature for this compound. This could be attributed to the use of coal fly ash as raw material, which contains mineralizers that promote the mentioned conversion.

The quantitative effect of the following parameters on the one single step pressureless infiltration characteristics of bilayer B4Cp/rice-husk ash (RHA) porous preforms by aluminum alloys was investigated using the Taguchi method and analysis of variance (ANOVA): infiltration temperature and time, B4C particle size, RHA percentage, percentage porosity in the preforms, and magnesium content in the alloy. The contributions of each of the parameters to the retained porosity, hardness and modulus of elasticity of the resulting bilayer composites were determined. The parameters that most significantly impact the modulus of elasticity (E) of the resulting composites are chemical composition of Al alloy followed by porosity of preforms and B4C particle size. Their relative contributions to the variance in the values of modulus of elasticity are 25.7, 22.48 and 18.44 %, respectively. Verification tests conducted using the established optimum parameters show a good agreement with those of projected values.

Non-planar iodinated pyrrole structures were found through DFT calculations of geometry optimization, when doping one pyrrole molecule with iodine atoms. This take us to a new mono-iodinated pyrrole structure in which one pyrrole molecule is attacked with one iodine atom in a pyramidal configuration. Then, the pyrrole molecule was attacked with two and until four optimized linear iodine atoms in a pyramidal structure configuration. The corresponding potential energy curves were also constructed in order to know what kind of adsorption (physisorption or chemisorption) is obtained, considering physisorption as lower than ten kcal/mol, and chemisorption greater than twenty kcal/mol according to the literature. Finally, it is known that halogenated pyrrole is a highly conductive material required in several fields.

When high strength and high ductility are required, the Twinning Induced Plasticity steels are an excellent choice. Their mechanical advantages are perfectly known in the automotive industry. Then, they are currently deeply studied. During the deformation at high temperature, TWIP steel experiences dynamic recrystallization. This mechanism results from dislocation interactions, and it depends of temperature, stress, strain, and strain rate. Experimental data give the maximum stress reached by the material, but the critical stress which determinates the DRX onset must be calculated from the strain hardening rate. Both stress and strain change simultaneously, and this variation gives the analytic data to determine σc, which is located at the inflection point of θ-σ plot. The main purpose of this paper was to study how the chemical composition and the experimental parameters (temperature and strain rate) affect the DRX, by the calculation and analysis of the σc values. Hot compression tests were applied to a pair of TWIP steels to compare the DRX onset and its relationship with the vanadium addition. The experimental variables were temperature and strain rate. The true stress–true strain plots were used to calculate σc by cutting data up to a previous point before the σp value, then, a polynomial fit and derivation were applied. The Zener-Hollomon parameter (Z) versus the stresses (peak and critical) plots show how the micro-alloying element vanadium improves the strain hardening in the analyzed TWIP steels.

Stress Corrosion Cracking (SCC) in a general term describing stressed alloy fracture that occurs by crack propagation in specifically environments, and has the appearance of brittle fracture, yet it can occur in ductile materials like AISI 304L used in internal components of Boiling Water Reactors (BWR). The high levels of oxygen and hydrogen peroxide generated during an operational Normal Water Condition (NWC) promotes an Electrochemical Corrosion Potential (ECP), enough to generate SCC in susceptible materials. Changes in water chemistry have been some of the main solutions for mitigate this degradation mechanism, and one of these changes is reducing the ECP by the injection of Hydrogen in the feed water of the reactor; this addition moves the ECP below a threshold value, under which the SCC is mitigated (-230mV vs SHE). This paper shows the characterization by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Raman Spectroscopy of the oxide film formed in to a crack propagated during a Rising Displacement Test method (RDT), on Hydrogen Water Chemistry (HWC) conditions: 20 ppb O2, 125 ppb H2, P=8MPa, T=288°C, using a CT specimen of austenitic stainless steel AISI 304L sensitized. The characterization allowed identifying the magnetite formation since an incipient way, until very good formed magnetite crystals.

In this work, we studied the synthesis of biodegradable copolymers of the type poly(isobutyl vinyl ether)-co-(ε-caprolactone) (PIBVE-co-PCL) using a homogeneous mono-cyclopentadienyltitanium catalyst and methylaluminoxane (MAO) as co-catalyst. These copolymers can also be used as plasticizers for flexible poly(vinyl chloride) (PVC), improving its thermal properties. The copolymer PIBVE-co-PCL could be synthesized with a high conversion (>90%). The use of 39 wt.% of the copolymer in the formulation of PVC decreases its glass transition temperature (Tg) by -6.51 °C. By varying the copolymer composition it is possible to obtain PVC with different Tg values that could be used for different applications. A particular application where one could use this type of copolymer is in PVC formulations for the fabrication of blood bags. The toxicity of dioctyl phthalate (DOP), which is the more commonly used plasticizer for PVC, limits the use of these formulations for the mentioned purpose. The PVC plasticized with the biodegradable copolymer showed an increase in the degradation temperature, improving the thermal stability of the PVC formulation in comparison with the phthalates usually used as plasticizers.

Cardiovascular diseases, frequently associated to the formation of aneurisms, are the mayor cause of mortality and morbidity in the world. Due to the increased need for the regeneration of arteries and veins, several natural and synthetic biopolymers such as poly(glycerol sebacate), PGS, have been studied to make blood vessel constructs. PGS elastomeric properties develop after it is crosslinked; however, the poor solubility of the material limits the process to fabricate useful constructs for tissue engineering by electrospinning, casting, or other methods. The structure and properties of electrospun scaffolds made from soluble poly(glycerol sebacate) and poly(ε- caprolactone), are reported here. Soluble PGS oligomers (o-PGS) of different molecular weight, obtained by the polycondensation reaction of sebacic acid and glycerol, were analyzed, including molecular structure, physical properties and solubility. Temperature, reactor atmosphere, and time of reaction strongly influenced the solubility, the molecular weight and molecular structure. To improve o-PGS processing and properties it was mixed with PCL to make electrospun scaffolds. In order to process the mixture by electrospinning, homogeneous solutions o-PGS and PCL were prepared. Because PCL is hydrophobic and o-PGS is hydrophilic selected solvent mixtures were tested to form the homogeneous solutions; the materials dissolved in a mixture of THF:DMF:DCM. Typical electrospinning parameters for preparing the tubular scaffolds at room conditions were: voltage 17.5 kV, needle-collector distance 20 cm and, relative humidity 30-35%, flow injection 0.5 to 2.0 ml/h. The initial mechanical properties of the biodegradable scaffolds were better than those made of natural grafts; the Young’s modulus ranged from 7.6 to 13.0 MPa, depending on electrospinning process parameters. The morphology and physical properties of electrospun PGS/PCL tubular scaffolds show useful features not found in similar constructs made by other methods. The 3D tubular scaffolds were built-up of layered porous walls to produce constructs of different pore size and fibers of different diameter. The porous area was one to two orders of magnitude higher than those produced at micrometer scale by conventional melting and dry/wet spinning methods. These scaffolds show useful characteristics for regenerative medicine such as physical properties; nanometric diameters; high surface/volume ratio; and potentiallity for adhesion and growth of living cells.

It is well-known that metal and alloys develop internal cavities when subjected to uniaxial or multiaxial tensile strains at elevated temperature. In most cases, cavitation may lead to premature failure during forming. Therefore, damage and fracture behavior imposes significant limitations in hot metal-forming processes. Although high-Mn austenitic TWIP steels exhibit a unique combination of strength and ductility, cavitation during hot working is one issue that must be tackled. The aim of this research work is to determine the effect of Ti microaddition on cavity mechanisms of Fe-22Mn-1.5Al-1.3Si-0.5C TWIP steel under uniaxial hot-tensile condition at 800 °C and constant true strain rate of 10-3 s-1. For this purpose, light optical (LOM) and scanning electron (SEM) microscopies and image analysis were applied to quantify cavities formation along longitudinal section of deformed samples near to the fracture surface. The number of cavities greater than 10 µm (critical length) in non-microalloyed and Ti microalloyed TWIP steels were 2.75 and 3.75 cavities/mm2, respectively. On the other hand, average cavity area was 125 and 152 µm2, respectively. Both TWIP steels showed cavities type “r”, “l” and “A”. Finally, Ti microaddition to TWIP steel resulted in a predominant brittle fracture behavior due to finer grain-boundary precipitation, which weakens grains cohesion and accelerates crack growth by grain-boundary sliding. In this case, crack growth behavior is explained in terms of a void interconnection mechanism.

Corrosion is a worldwide, crucial problem that strongly affects natural and industrial environments, in particular the oil and gas industry. Natural gas (NG) is a source of energy in industrial, residential, commercial and electric applications. The abundance of NG in many countries augurs a profitable situation for the vast energy industry. NG is considered friendlier to the environment and with lesser greenhouse gas emissions as compared with other fossil fuels. In the last years, shale gas is increasingly exploited in U.S. and Europe, applying a hydraulic fracturing technique, for releasing gas from the bed rock by injection of saline water, acidic chemicals and sand to the wells. Various critical sectors of the NG industry infrastructure suffer from several types of corrosion: steel casings of production wells and their drilling equipment; gas conveying pipelines including pumps and valves; plants for regasification of liquefied natural gas (LNG) and municipal networks of NG distribution to the consumers. Practical technologies that minimize or prevent corrosion include selection of corrosion resistant engineering materials, cathodic protection, corrosion inhibitors, and application of external and internal paints, coatings and linings. Mexico is undergoing an intense reform process of the energy sector, that involves its oil, NG and electricity industries. Typical cases of corrosion management in the NG industry are presented based on the authors experience and knowledge.

Amorphous silicon (α-Si) was deposited on glass substrates by PECVD at different deposition conditions in order to characterize the residual stress on the film. Subsequently, a thermal-annealing was applied for different times at 400 °C in a N2 atmosphere, aiming to reduce the stress in the films. The deposition power was between 15 and 30 W at 13.56 MHz, the pressure in the chamber was adjusted in a range from 600 to 900 mTorr, and the temperature was varied from 140 to 200 °C. The stress was determined by using the Stoney equation, measuring the curvature and thickness of the α-Si films with a stylus profilometer. A deposition rate between 7-24 nm/min was obtained, and the time for thermal-annealing needed to reduce the stress was reduced from 10 to 2-4 h, obtaining a minimum compressive stress of 17 MPa. With this value of stress, it was possible to use the α-Si as masking material for wet etching of glass during the manufacturing of microfluidic devices, in order to obtain microstructures in the glass with 150 μm in depth.

The array of the TiO2 nanotubular films, also called one-dimensional nanostructures is carried out by electrochemical anodization tests, for which, titanium sheets were used with a high purity (99.7% and 0.25 mm thickness) in a solution of deionized water and glycerol (50:50 vol.%) + 0.27M NH4F applying a voltage of 20V. Electrochemical tests were performed at an anodization time of 2:30 hours and 3:30 hours. For the tests mirror polished foils and unpolished foils with flat surfaces to achieve better uniform arrays during the anodic growth of nanotubes were used. After anodizing, samples were observed in the scanning electron microscope (SEM) to determine the geometry and morphology of the films. Also, potentiodynamic polarization curves were performed for samples crystallized at 600 °C and 450 °C (polished and unpolished) to determine the electrochemical stability of the films, which were presented at two aqueous solutions: 1M of Na2SO4 (pH= 6.7) and 1M Na2SO4 + H2SO4 (pH= 3.2). Mechanical characterization was also performed by nanoindentation technique through the application of loading/unloaings of: (1, 2.5, 5, 10 mN). Chemical characterization was performed using XRD analysis, with the aim to determine the crystalline phases formed in the films crystallized at 450 °C and 600 °C. The electrochemical characterization showed that the TiO2 nanotubular film obtained by mirror polished and crystallized at 600 °C showed better electrochemical stability. Nanoindentation tests showed deformation curves, and the parameters such as hardness, Vickers hardness, elastic modulus and the maximum penetration depth were determined as mechanical parameters.

Magnetic nanoparticles (MNPs) are a class of materials that can be manipulated under the influence of an external magnetic field. Thanks to the ability of the MNPs to be guided by an external magnetic field that is like "action at a distance", combined with their low cytotoxicity and the intrinsic penetrability of magnetic fields into human tissue, opens up many applications involving the transport and/or immobilization of biological entities [1, 2].

This work is focused on the synthesis of magnetite nanoparticles by varied methods, their functionalization with nickel tetrasulfonated phthalocyanine, and the corresponding physicochemical characterization and colloidal stability studies in biologically compatible media. The in vitro production of singlet oxygen by these nanoparticles through photochemical stimulation in ultraviolet and visible region was evaluated, resulting in 4.5 and 4 µM respectly to magnetite synthetized in the group. The increase reactive oxygen species concentration in the cellular environment can result in modification and damage of cellular components, and potentially, cell death and necrosis. Therefore, these materials offer the promise of revolutionary tools for photodynamic therapy and hyperthermia, which are attractive strategies for cancer therapy without systemic toxicity.