Portugaliae
Electrochimica Acta

This work focused on developing prediction models using ANN, in order to forecast the long-term performance of reinforcements in concrete slabs containing pure Mg anodes, and subjected to Cl- ingress. The experimental set-up consisted of two built RCC slabs with 1000 x 1000 x 100 mm. Slab #1 was cast with 3.5% NaCl by cement weight. Slab #2 was cast without NaCl. Considered input parameters were the distance of the anode from the point under consideration in x and y-axes, T, RH and concrete age in days. HCP values concerning SCE were considered output. Experimental values consisted of 80 HCP per slab/day. These were collected for 270 days, in order to generate the prediction model. The learning heuristic used LM supervised learning in feed-forward. A two-layer feed-forward network, with ten hidden sigmoid neurons and trained linear output neurons, was employed. The network architecture [5-10-1] and ten neurons in the hidden layer were used for all prediction models. The accuracy level of results obtained with LM was above 97%. Keywords: ANN model; Cl-induced corrosion; HCP; SA from Mg.

Patients with fractures require internal fixations, since treatment options are limited to metallic implants and autologous bone grafts. These limitations include chances of infection transference, quantity restrictions and the need for additional surgery. Bone tissue engineering seeks to address these limitations through the development of biocompatible bone scaffolds. This study fabricated a PLA based scaffold that sought to address some of the challenges associated with currently available treatment options. The methodology involved acquiring raw eggshells, which were rinsed with water and calcined with concentrated H3PO4. Hitherto, HAp powder was extracted from eggshells, and its presence was confirmed using color test. PLA (60,000 molecular weight) was procured from Sigma Aldrich, which was used with HAp powder, to form the composite, employing sol gel technique. SEM morphology established PLA, which has polymeric binding properties, as the 3D scaffold with the highest Ct (PLA/HAp (45/55 wt.%). It had a more consistent crystal and pore formation and weaker grain boundaries. FTIR analysis showed PLA characterizing peaks, and that functional groups present in 3D scaffold are not toxic to the body. X-RD spectra confirmed PLA and HAp presence in 3D scaffolds. However, peaks intensities decreased with lower Ct of HAp, and those of PLA increased in the 3D scaffold. This indicates that PLA and HAp particles have semi-crystalline and crystalline structures, respectively. Thus, 3D scaffolds can be tailored for many biomedical applications. Keywords: bone fillers; characterizations; HAp; PLA; scaffold.

Different Ct of KBE from its leaves were used to study its effect on MS corrosion resistance. Electrochemical methods such as PDP, EIS and WL tests were herein used. Experimental results showed that, with higher Ct of KB, its IE(%) increased. The highest corrosion IE(%) of 98.41, at 1600 ppm KBE in a 0.5 M H2SO4 solution, was obtained. The inhibitor’s adsorption onto the MS surface was excellent, since it created a monolayer. KBE´s adsorption mechanism obeyed Langmuir’s isotherm. SEM analysis established the development of a protective layer on the MS surface. Keywords: CI; EIS; LPR; PDP;SEM; WL.

employing Lingane’s equation in a simple and extended form. Ionic strength was kept constant by using NaClO4 and KNO3 as SE. All measurements were performed at a constant T of 298±1 K. The approximation of all possible Lingane’s equations was established. According to obtained results, it was concluded that the equation should be used in its extended form. In KNO3 and in NaClO4, q was found to be 5 and 6, and  logarithms were found to be 21.20 and 24.47, respectively. Spectrophotometric study was also performed to determine stoichiometry and  of Cd(II)/Na-DDTC complex in the same SE. Data indicated that Na-DDTC should be combined with Cd in molar ratios of 1:5 (ML5), in KNO3, and of 1:6 (ML6), in NaClO4.  logarithms were calculated to be 22.26 and 23.94, in KNO3 and NaClO4, respectively. IE(%) of Na-DDTC as an ecofriendly CI for CS in 0.5 M H2SO4 medium was also investigated using WL measurements. Experimental results showed that IE(%) increased with higher inhibitor’s Ct. The inhibitor’s adsorption onto the CS surface obeyed Langmuir’s isotherm, and it proceeded by both physisorption and chemisorption modes. ΔGads was determined. The effect of Cd2+ addition, which formed a complex with Na-DDTC, was also studied. Keywords: B; CI; DPV; Job’s method; Na-DDTC.

In the present study, a thin film of NixSy was deposited on an ITO GP by SILAR method. This film was characterized by UV-vis reflectance and FTIR spectroscopy. UV-vis reflectance revealed that Eg from NixSy was 1.55 eV. After coating, ITO GP Eg decreased from 1.88 to 1.55 eV. This indicates that the film functioned as a semi conductor. UV-vis absorbance showed that the film absorbance occurred at 322.00, 388.80 and 396.25 nm, with peak intensity of 1.229, 0.934 and 0.916 AU, respectively. FTIR spectra confirmed NixSy formation on ITO GP by SILAR technique. Thus, it was encouraging to note that NixSy was successfully prepared by this method. Electrochemical studies, such as polarization technique and AC impedance spectra revealed that current flowing through ITO GP increased after NixSy coating by SILAR method. These findings may be useful for solar panel systems used in marine environments. Keywords: Eg; electrochemical studies; ITO GP; NixSy; SILAR method; thin film.