The purpose of this study is to evaluate in detail the usability of new cellulosic fibers extracted from the stem of the plant Strelitzia reginae, as a potential reinforcement for polymer composites. The morphological, physical, thermal, and mechanical properties of fibers were addressed for the first time in this paper. Both untreated and alkali-treated fibers were characterized, using scanning electron microscopy (SEM), Fourier-transform infrared, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), optical microscope, and X-ray diffraction (XRD) and applying tensile test for determining the mechanical behavior. For both fiber treated at one hour (T1H) and at four hours (T4H), the stem anatomy and fiber SEM micrographs showed a strong presence of fiber cells. Thermogravimetry and DSC showed that the fiber was thermally stable up to 233°C for untreated fiber, 254 and 240°C, respectively, In single-fiber tensile tests, it was observed that the fibers extracted from the stem of Strelitzia reginae were strong. The mean values of Young’s modulus exhibited by untreated fibers and treated (T1H) and (T4H) are, respectively, 9.89 GPa, 12.08, and 18.39 GPa. Also mean values of tensile strength are 271.79, 306.23, and 421.39 MPa. The XRD reveals the presence of cellulose with a Crystallinity Index of 70% for raw fiber and 72% for the treated one. Fourier-transform infrared analysis well demonstrated the effect of chemical treatment. It can be concluded from the results of all above experiments that the Strelitzia reginae fibers (SR) could serve as a possible reinforcement in composite materials.

The virulence and resistance of pathogenic microorganisms are promoted by quorum-sensing (QS) mediated traits and biofilms. The development of antimicrobial agents which can reduce the incidence of microbial resistance by disrupting the establishment of biofilms and QS, constitute a suitable strategy to reduce the emergence of pathogenic strains that are resistant to antibiotics. In this study, 3-(1,3-dithian-2-ylidene) pentane-2,4-dione (1) and ethyl-2-cyano-2-(1,3-dithian-2-ylidene) acetate (2) were successfully synthesized and characterized using EIMS, 1H NMR and 13C NMR techniques. On S. aureus, both compounds had MIC (minimal inhibitory concentrations) of 0.625 mg/mL while on E. coli and C. albicans, compound 2 showed higher activity than compound 1. All compounds inhibited formation of biofilms by C. albicans and S. aureus at sub-MIC with compound 1 being more active than compound 2. On E. coli, only compound 1 inhibited biofilm formation. Violacein production of violacein in C. violaceum CV12472 and quorum sensing in C. violaceum CV026 were inhibited indicating that the compounds could block signal production and reception. Anti-quorum sensing at sub-MIC concentrations revealed by inhibition zones were 13.0±0.5 mm and 8.0±0.5 mm at MIC and MIC/2 respectively for compound 1 and for compound 2, they were 11.5±0.4 mm and 7.5±0.0 mm at MIC and MIC/2 respectively. Concentration-dependent swarming motility was exhibited by both compounds with compound 1 slightly more active than compound 2. The results indicate that the organosulphur compounds could be suitable candidates for modern antibiotics.

Shear deformation of composite reinforcement is the most significant and important mechanism of material characterization. So, in-plane shear properties of composite reinforcement are important parameters for determining application and use of this category of materials. The bias extension test is frequently employed to investigate the in-plane shear behavior of composites fabrics with a length equal to or greater than twice its width. In the first part of this work, bias extension tests on non-crimp fabrics have been conducted. Force and displacement were measured and registered. From obtained data, shear angles and normalized shear forces were theoretically determined. The second part was a finite element analysis of the same test based on hypo elastic model at macroscopic scale. The software ABAQUS/Explicit was used to carry out the finite element analysis in the work.

Abstract. A novel Butanolic extract of Ephedra major (denoted EBEM) was investigated as corrosion inhibitor for mild steel in 1 M hydrochloric acid solution. The investigation was carried out using weight loss, electrochemical impedance spectroscopy (EIS), Tafel polarization measurements, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) methods. The effect of temperature on the corrosion behavior of steel in HCl with the addition of the inhibitor was investigated in the temperature range 20-60°C. The inhibition efficiency was observed to increase with increasing concentration of the extract EBEM and deceased with increasing the temperature. Tafel curves have revealed that the EBEM possesses the indices of a mixed inhibitor. The adsorption of the inhibitor on the steel surface, follow Langmuir isotherm and its mode was found to be physical adsorption. Thermodynamic parameter (ΔG°ads) and activation parameters (Ea, ΔHa and ΔSa) were calculated to investigate the mechanism of inhibition. Obtained data were analyzed by suggesting two mathematical models based on linear and quadratic regressions, which takes into account the effect of concentration and temperature upon the inhibition efficiency. Experimental data were in good agreement with those predicted by both models.   Resumen. Se investigó un nuevo extracto butanólico de Ephedra major (denominado EBEM) como inhibidor de la corrosión del acero al carbono en una solución de ácido clorhídrico HCl 1 M. La investigación se llevó a cabo mediante métodos de pérdida de peso, espectroscopia de impedancia electroquímica (EIS), mediciones de polarización de Tafel, espectroscopia infrarroja por transformación de Fourier (FT-IR) y microscopía electrónica de barrido (SEM). Se investigó el efecto de la temperatura en el comportamiento de la corrosión del acero en HCl con la adición del inhibidor en el rango de temperaturas de 20-60°C. Se observó que la eficacia de la inhibición aumentó con el incremento de la concentración del extracto EBEM y disminuye con el aumento de la temperatura. Las curvas de Tafel han revelado que el EBEM posee los índices de un inhibidor mixto. La adsorción del inhibidor en la superficie del acero sigue la isoterma de Langmuir y su modo se encontró que era de adsorción física. Se calcularon los parámetros termodinámicos (ΔG°ads) y de activación (Ea, ΔHa y ΔSa) para investigar el mecanismo de inhibición. Los datos obtenidos se analizaron proponiendo dos modelos matemáticos basados en regresiones lineales y cuadráticas, que tienen en cuenta el efecto de la concentración y la temperatura sobre la eficacia de la inhibición. Los datos experimentales coincidieron con los predichos por ambos modelos.

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