Synthetic superabsorbent polymers (SAPs) are used in concrete for various applications such as internal curing and frost resistance. However, the addition of these SAPs may lead to a significant decrease in mortar strength, especially when high amounts of SAP are necessary. This is the case for example when self-sealing and -healing of cracks is strived at. In order to overcome this bottleneck, the present work focuses on the application of biopolymers as SAPs. The work especially aims to evaluate the potential of both sodium alginate (NaAlg) as well as physically cross-linked calcium alginate (CaAlg) as SAPs to establish a sustainable approach towards self-sealing and -healing concrete without impairing mechanical strength. First, the swelling properties in both demineralized water and cement filtrate solution are tested. Subsequently, the mechanical properties of mortar mixtures in the absence and the presence of SAPs are compared by performing flexural and compressive tests. The alginates show a swelling capacity up to 72 times their own weight in aqueous solutions. Interestingly, they lead to a minor reduction in compression strength (up to 15% upon addition of 1m% SAP). These biopolymers show high potential for enabling concrete repair, more specifically, for the self-sealing and -healing of cracks without impairing the strength.

In the last decades the interest in organic conductors has growth, so they have become the object of study of many research groups that are interested in developing new materials with important conducting properties. The charge transfer complexes (CTC) represent an important kind of organic conductors, because they exhibit high conductivity values, as well as versatility for their design.

In this work, the charge transfer complex (CTC) formed by substituted pyrrole and tetrathiofulvalene (TTF) was obtained by means electrochemical synthesis, the resultant colored mix was characterized by Mass spectrometry, NMR and EPR studies, its intrinsic electronic behavior was measured by a four point probe method, besides theoretical calculations were carried out on the possible structures of the resultant molecular adduct. All the results show that there is a net transfer of an electron between both organic moieties in a solution giving place to a semiconductor species.

Concrete is a composite material, composed of cement, sand, gravel and water, reinforced with steel bars or mesh. It is used for the construction of infrastructure assets such as airports, dams, ports, bridges and road ways. Polymer concrete is a relative new material containing a thermosetting resin (instead of water) displaying improved mechanical strength, low permeability, greater corrosion resistance and higher durability. It is employed for new construction and old concrete reparation in the chemical, food, fertilizer, mine and civil industries. Polymer concrete pipe specimens, reinforced with glass-fibers were prepared and exposed in a salt spray (fog) chamber, operating with a NaCl solution, following ASTM standard B-117-11. The deterioration effects were assessed by testing the physical and mechanical properties, before and after the exposure in the spray chamber, in accordance with standard ASTM D3039-2013. Corrosion resistance was evaluated applying ASTM standard C876-2013. The result of this work are presented, illustrated and discussed.

This paper studies the performance of (U, Pu)C fuel in a hexagonal assembly of a GFR (Gas Fast Reactor). The SCALE 6.0 (Standardized Computer Analysis for Licensing Evaluation version 6.0) code was used in the calculation. The goal is to evaluate the behavior of the infinite multiplication factor (k inf ) for a heterogeneous assembly model using four nuclear data libraries: V6-238, V7-238, ENDF/B-VI.8 and ENDF/B-VII.0. The burnup of (U, Pu)C was performed by the TRITON-6 module, and the isotopic concentrations were evaluated during the cycle. The present work comprises calculations at Zero Power and Full Power condition. This study intends to achieve more information about different Fast Reactors.

Chitosan is biocompatible polymer has a great commercial interest because it can be processed in a sort of devices varying in shape and size, such as membranes, gels and nanoparticles. Mostly, the cell’s attachment and proliferation are very positive on nanostructurated materials with a three-dimensional formation. An irreversible network can be produced by covalently binding the polymer to the cross-linker molecules. Chitosan nanoparticles were prepared using glutaraldehyde as cross-linker. This crosss-liker mostly reacts with chitosan amino groups. In order to control and understand the physical characteristics of chitosan nanoparticle, in this work is showed the molecular behavior of chitosan/glutaraldehyde from the viewpoint of molecular interactions base in a series of molecular dynamics (MD) computer simulation. The results indicated the conformations of both molecules, which had a significant influence on the molecular association. The chitosan chains were uniformly distributed presenting a high flexibility and preference for the relaxed two-fold helix. This was due to the various associations such as intramolecular chitosan interactions –O-H···O-C-. While the chitosan-glutaraldehyde associations were due to the positive net charge density of hydrogens in the chitosan plus - H2N···C=O associations. In solid state chitosan nano and microparticles were analyzed by scanning electron microscopy (SEM). According to the micrographs results, the nanoparticles presented a monomorphism with piles of particles arranged in linear order which was consistent with the conformations determined by simulation.

The optical and structural properties of co-doped HfO2 thin films with rare earth trivalent ions prepared by ultrasonic spray pyrolysis technique, are reported. An arrangement of multi-layer (Si-SiO2-HfO2:Eu3+-HfO2:Tb3+-HfO2:Tm3+-SiO2) were deposited on silicon substrates at temperatures from 400 to 550°C, using acetyl acetonates as precursory reagents. A refractive index value of 2.1 was determined by spectral ellipsometry. The surface morphology was obtained by AFM measurements. For 50 to 550 nm thickness films, an average roughness value of ∼56.8 Å was obtained for different substrate temperatures and grown deposition times. EDS measurements showed the presence of hafnium, and rare earths dopants as elemental composition. XPS measurements demonstrated that hafnium and rare earths oxidation species are formed at hafnium dioxide thin films. Photoluminescence emission spectra of multi-layer structures present characteristic emission peaks associated with Tb+3, Eu3+, and Tm3+ dopants. The results presented above motivate us to consider that these multilayer structures could be appropriate to be used as a rare earth host to improve optical emission.

Hydrogenated amorphous silicon carbide (a-SiC:H) was deposited by radiofrequency-plasma enhanced chemical vapor deposition (RF-PECVD) on monocrystalline silicon substrates with different process parameters in order to analyze the residual stress, and the roughness and uniformity of the films, which are the most important characteristics in the production of membranes for cell culture. The residual stress was calculated using Stoney's equation by measuring the thicknesses of the substrate and the deposited film, in addition to the radius of curvature of the substrate with and without deposited material. From the results it was observed that as power increases from 15 to 30 W, the residual stress increases from -180 to -400 MPa. Even at low power, the residual stress is high. However, an annealing process at 450 °C in N2 atmosphere significantly reduces the residual stress to 7 MPa. It was found that the film uniformity increases when the pressure rises in the process chamber from 450 to 900 mTorr. Finally, the RMS roughness (0.7 to 5.1 nm) can be controlled by the power and pressure, allowing us to obtain a material with excellent morphological characteristics for the adherence and growth of specific cells.

Frictional behaviour of multilayered graphene was studied in air with different relative humidity (RH) levels (10–52% RH). Pin-on-disk type sliding tests were performed and the running-in and steady state coefficient of friction (COF) values were measured against M2 tool steel counterface. On increasing the RH, multilayered graphene showed a reduction in steady state COF from 0.11 at 10% RH to 0.08 at 52% RH. The low steady state COF values observed in graphene could be attributed to the transfer layer formed on the M2 tool steel counterface. A sliding-induced structural change was observed in graphene transfer layers which could have facilitated the graphitic transfer layer formation. The multilayered graphene showed a lower steady state COF values at all RH compared to non-hydrogenated diamond-like carbon (NH-DLC) which recorded a steady state COF of 0.47 at 10% RH and 0.25 at 52% RH.

A simulation model is presented, where temperature, phases and internal stresses can be predicted as a function of time during the heating of large steel ingots for forging. Heating cycle measurements and computer simulations are compared for an A105 steel grade 34-Ton tapered ingot. A study of the heat transfer inside a natural gas-fired furnace was carried out to make an estimation of internal stresses due to thermal expansion and phase transformation from α ferrite and pearlite to γ austenite during heating. The model was validated with a second test of an AISI 4330 steel grade 35.4-Ton ingot. The simulation model described can calculate internal stresses in any ingot in order to optimize its heating cycle without compromising ingot internal quality, reducing energy consumption and increasing productivity of the furnace.