Portugaliae
Electrochimica Acta

Enhancing techniques for obtaining fluted pumpkin seeds oil (PSO), technically known as Telfairia occidentalis, was the goal of this study. The main objective was to analyse chemical and physical properties of the extracted oil, expediting the process by using response surface methodology (RSM) and artificial neural networks (ANN). Fluted PS were purchased from a local market, carefully washed, sun-dried, sorted from chaff and crushed. Using a Soxhlet extractor and n-hexane as solvent, PSO was extracted. For optimisation, a three-level, three-factor Box-Behnken design with 17 iterations was used. The sample’s weight, solvent volume and extraction time were the main factors taken into account for optimisation. According to the study's findings, RSM optimisation produced a 41.58% (w/w) pumpkin seeds oil yield (PSOY). ANN approach, on the other hand, produced a greater PSOY of 41.66% (w/w), demonstrating its superior capacity to forecast the ideal oil output. Standard industrial procedures were used to determine PSO density, specific gravity, moisture content and acid, saponification, iodine and peroxide values, among other parameters. When ANN and RSM were compared, it was found that the former was more reliable in predicting PSOY, since it had better coeeficients of determination (R2) and R2 adj. values (0.9746 and 0.9893) and lower root mean square error values (0.9889 and 0.9965). In conclusion, this study highlights the potential uses of fluted PS across a range of sectors. It emphasises how using statistical analytical approaches can significantly improve production operations. Keywords: ANN; extraction; percentage PSOY; PS; RSM.

To discriminate the structures of two polymers, 1,4-transpolymyrcene (TPM) and 1,4-cis polymyrcene (CPM), at molecular level, nuclear magnetic resonance (NMR) was herein used as the main method. However, to enhance the reliability of findings, this method involves a longer ordering time, which results in higher costs. A simple electrochemical technique, based on the use of cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS), was incorporated into the approach of this study. CV provided information on the polymers’ electronic properties, while EIS enabled to assess electrochemical properties and conductivity. These techniques were utilized to identify distinctions between TPM and CPM, without resorting to NMR analysis, and they provided crucial data on the polymers’ structure and electrochemical behavior. By comparing results obtained by these two approaches, the validity of conclusions drawn from NMR analysis was confirmed. This hybrid approach, combining advanced NMR techniques with electrochemical methods, enabled a more comprehensive characterization of TPM and CPM. Thus, it offers an integrated and more reliable approach to molecular structure discrimination, enhancing the understanding of natural polymers in diverse applications. Keywords: CPM; CV; EIS; NMR analysis; SWV; TPM.

forming an oxide layer on their surface. This causes several undesirable effects such as corrosion and malfunction. CR of Thermo Active Super Elastic Alloy (TASEA) immersed in artificial sweat (AS) with 100 ppm NaCl and 100 ppm urea was herein investigated and compared by polarization study and AC impedance spectra. It was seen that CR of TASEA immersed in AS with 100 ppm NaCl/urea increased. When TASEA was immersed in AS with 100 ppm NaCl linear polarization resistance (LPR) increased from 1760283 to 9506106 Ohm/cm2, icorr decreased from 2.382 x 10-8 to 4.008 x 10-9 A/cm2, Rct increased from 4884 to 12210 Ohm/cm2, impedance increased from 4.367 to 4.8, Cdl decreased from 10.442 x 10-10 to 4.1769 x 10-10 F/cm2 and phase angle increased from 48.1 to 68°. When TASEA was immersed in AS with 100 ppm urea LPR increased from 1760283 to 2430930 Ohm/cm2, icorr decreased from 2.382 x 10-8 to 2.004 x 10-8 A/cm2, Rct increased from 4884 to 10740 Ohm/cm2, impedance increased from 4.367 to 4.777, Cdl decreased from 10.442 x 10-10 to 4.748 x 10-10 F/cm2 and phase angle increased from 48.1 to 66°. Keywords: AC impedance spectra; AS; CR; NaCl, polarization study; TASEA; urea.

Polyaniline (PANI) is the oldest conducting polymer which has drawn demanding attention, due to its unique conductive properties and versatile applications in various fields. Carbon Nanofiber (CNF) is another promising material, due to its high electrical, thermal conductivity and great mechanical qualities, with various uses, including electrode constituents for batteries and supercapacitors (SC). The experiment of this study involved PANI and PANI/CNF synthesis, as well as the fabrication of their thin films on Indium Tin Oxide (ITO), using DCT. The primary focus was to examine electrical conductivity as a significant factor. The electrical conductivity of the hybrid composite consisting of PANI/CNF thin film-coated ITO was predominantly influenced by its dispersion state and thickness. Electrical conductance of PANI/CNF thin film on ITO glass prepared by Dip Coating Technique (DCT) was 41.78990 µS, whereas for PANI on ITO, and for bare ITO glass, was 7.30465 and 1.05238 µS, respectively. So, this study introduced a novel avenue for research in the domain of conducting polymers and their thin films on ITO substrates. Keywords: CNF; conducting polymer; DCT; hybrid composites; ITO; PANI.

Biomass torrefaction into fuel pellets is deemed a sustainable energy solution, which could mitigate over-dependency on fossil fuels. This study examined the effects of pelletization and torrefaction on selected physical and thermal properties of corncob waste (CW). Corncob samples were collected, sorted and pulverized, before torrefaction pre-treatment. Raw corncob (RC) and torrefied corncob waste (TCW) were screened to 0.3, 0.5 and 1.0 mm. Using starch (5 wt.%) as binder, RC and TCW pellets were produced, at compaction pressures of 50, 75 and 100 MPa. They were characterized by proximate, ultimate, physical, thermogravimetric and thermal analyses. All samples exhibited good quality and thermal properties, but those from TCW were better. Relaxed density of RC and TCW pellets varied from 700 to 876 and 616 to 800 kg/m3, respectively. Maximum relaxation values for RC and TCW pellets were 1.43 and 1.07, respectively. TCW sample (1.0 mm) had higher heating value of 25.8 MJ/kg, which was 29% greater than those from lignite or brown coal. Thus, pellets produced from TCW are suitable for energy applications. Keywords: compaction pressures; pelletized particles; particle size; TCW; TGA.