Ultrahigh molecular weight polyethylene: Catalysis, structure, properties, processing and applications

A critical review on microplastics, interaction with organic and inorganic pollutants, impacts and effectiveness of advanced oxidation processes applied for their removal from aqueous matrices

Ultra-High Molecular Weight Polyethylene (UHMWPE) is used in biomedical applications due to its high wear-resistance, ductility, and biocompatibility. A great deal of research in recent decades has focused on further improving its mechanical and tribological performances in order to provide durable implants in patients. Several methods, including irradiation, surface modifications, and reinforcements have been employed to improve the tribological and mechanical performance of UHMWPE. The effect of these modifications on tribological and mechanical performance was discussed in this review.

https://www.mdpi.com/2073-4360/12/2/323/pdf

Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) as a Promising Polymer Material for Biomedical Applications: A Concise Review

Sodium montmorillonite organically modified by octadecylammonium (Np-Clay) and zinc oxide nanoparticles (Np-ZnO) were incorporated into chitosan (C) matrix in different proportions to evaluate its mechanical properties and antimicrobial activities. The composites were obtained by polymer intercalation method in solution using acetic acid (1% v/v) as solvent. The functional groups, thermic behavior and surface morphology of the chitosan film and of the composites prepared with different percentages of Np-Clay and Np-ZnO were characterized through Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed that a combined effect of clay and zinc oxide increases significantly the mechanical properties of pure chitosan. FTIR results confirmed good compatibility among functional groups of chitosan, montmorillonite/metallic oxides. The Np-ZnO distribution became more uniform in chitosan films when the Np-clay was incorporated, thus, the Np-Clay compatibilizes the Np-ZnO with the chitosan and the mechanical properties improved and without affecting the antimicrobial activity of the films. The thermal degradation temperature of the chitosan did not change significantly with the addition of Np-Clay, but changes significantly with Np-ZnO addition. In antimicrobial test was found that the chitosan and Np-ZnO showed a synergistic effect against to Escherichia coli and Staphylococcus aureus. The addition of Np-ZnO and C-Clay in chitosan resulted in enhancement of mechanical and antimicrobial properties, turning this material prospective for food packaging applications.

Mechanical, Thermal and Antimicrobial Properties of Chitosan-Based-Nanocomposite with Potential Applications for Food Packaging

Green synthesis of zirconia nanoparticles based on Euclea natalensis plant extract: Optimization of reaction conditions and evaluation of adsorptive properties

Advances in ultra high molecular weight polyethylene/hydroxyapatite composites for biomedical applications: A brief review.

Indicators are substances that change color as the pH of the medium. Many of these substances are dyes of synthetic origin. The mulala plant (Euclea natalensis), which roots are commonly used by rural communities for their oral hygiene, and roseira (Hibiscus rosa-sinensis), an ornamental plant, are abundant in Mozambique. Currently, synthetic acid-base indicators are most commonly used but have environmental implications and, on the other hand, are expensive products, so the demand for natural indicators started. This study investigated the applicability of aqueous extracts of H. rosa-sinensis and E. natalensis as acid-base indicators. Ground on this work, the extracts can be used as acid-base indicators. On the basis of the absorption spectroscopy in both the UV-Vis region and previous studies, it was possible to preliminarily pinpoint anthocyanins and naphthoquinones as responsible for the shifting of colors depending on the pH range of aqueous extracts of H. rosa-sinensis and E. natalensis. These natural indicators are easily accessible, inexpensive, easy to extract, environmentally safe, and locally available.

Aqueous extracts of Mozambican plants as alternative and environmentally safe acid-base indicators

Transmission infrared spectroscopy (FTIR) was used to study the effect of the temperature and concentration of octadecylamine (surfactant) in the conformation state of amine chains incorporated in a bentonite matrix by organophilization process. The temperature is the most important factor in conformational changes-gauche/trans. Whereas the simultaneous increase of the temperature and concentration of surfactant favors the disordered conformation-gauche. This result is very important in the development of organo-bentonite based polymeric nanocomposites because the intercalation of the polymer in the galleries of the organo-bentonite is dependent on the conformation of the alkyl chains.

Simultaneous Effect of Reaction Temperature and Concentration of Surfactant in Organo-Bentonite Synthesis

Hydropower energy is one of most promising clean energy technologies, however this energy technology has many challenges. Compared with other renewable energies for example biomass, solar and wind energies, it has high capital investment cost. In Mozambique, access to conversional energy in form of electricity has been limited to most of the rural population. The objectives of the investigation research are to analyze Chua micro-hydropower plant exploration in Manica district in Mozambique and to examine the possibility of increasing energy production. The current total installed power generation capacity in Mozambique is about 939 MW. Hydropower contributes 561 MW, making a contribution of 61%. Oil contributes 27%, and natural gas contributes 12% of the total electric grid generation in Mozambique.

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Jonas Valente Matsinhe

Papers

Advances in ultra high molecular weight polyethylene/hydroxyapatite composites for biomedical applications: A brief review.

Aqueous extracts of Mozambican plants as alternative and environmentally safe acid-base indicators

Simultaneous Effect of Reaction Temperature and Concentration of Surfactant in Organo-Bentonite Synthesis

Capacity Optimization Study of Chua Mini-Hydropower Plant at Chua River, Manica, Mozambique

Formulação de materiais vitreos a partir de cinza pesada resultante da queima de carvão mineral: efeito de fundentes