The role of the Tm3+ concentration on CaMoO4 properties processed by microwave hydrothermal under stirring condition

The compounds based on calcium molybdate (CaMoO₄) are the subject of extensive research due to their excellent optical properties and a broad range of potential technological applications. In this work, we report a systematic study of CaMoO₄:Tm³⁺ phosphors synthesized by coprecipitation and processed in a microwave-hydrothermal system at low temperature (100°C) and stirring. The effect of the Tm³⁺ doping content (0%–12%) is studied in full detail to understand their role in the CaMoO₄:Tm³⁺ morphological, structural, and luminescent properties. The X-ray diffraction, Raman, and Fourier Transform Infrared spectroscopic techniques revealed that all the prepared powders have a tetragonal crystal structure with a distinct density of cation vacancies and structural disorders. The band gap remains almost constant for doping levels lower than 8%, but it narrows strongly for powders doped with 12% Tm³⁺ ions. The designed phosphors have shown two emission bands in which intensity depends on the Tm³⁺ ions doping level. For doping levels lower than 2%, the photoluminescence profile displays a broad emission band peaking at 543 nm (green). For concentrations higher than 4%, the band centered at 543 nm decreases in intensity and the near-infrared emission band at around 800 nm, assigned to ³F₃, ³H₄ → ³H₆ transitions from Tm³⁺ ion, become more intense. The outcomes of this work reveal that appropriated Tm³⁺ ions doping levels can be applied to suppress the PL emission in the visible range and improve that in the near-infrared region in CaMoO₄-based materials.     

Extraction and characterization of hydroxyapatite-based materials from grey triggerfish skin and black scabbardfish bones

The conversion of food industry by-products to compounds with high added value is nowadays a significant topic, for social, environmental, and economic reasons. In this paper, calcium phosphate-based materials were obtained from black scabbardfish (Aphanopus carbo) bones and grey triggerfish (Balistes capriscus) skin, which are two of the most abundant fish by-products of Madeira Island. Different calcination temperatures between 400 and 1000°C were employed. Materials obtained from calcination of bones of black scabbard fish were composed by homogeneous mixtures of hydroxyapatite (Ca₁₀(PO4)₆(OH)₂, HAp) and β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP). Because of the high biocompatibility of HAp and the good resorbability of β-TCP, these natural biphasic materials could be very relevant in the field of biomaterials, as bone grafts. The ratio between HAp and β-TCP in the biphasic compound was dependent on the calcination temperature. Differently, the material obtained from skin of grey triggerfish contained HAp as the main phase, together with small amounts of other mineral phases, such as halite and rhenanite, which are known to enhance osteogenesis when used as bone substitutes. In both cases, the increase of calcination temperature led to an increase in the particles size with a consequent decrease in their specific surface area. These results demonstrate that from the fish by-products of the most consumed fishes in Madeira Island it is possible to obtain bioceramic materials with tunable composition and particle morphology, which could be promising materials for the biomedical field.     

Sofosbuvir Selects for Drug-Resistant Amino Acid Variants in the Zika Virus RNA-Dependent RNA-Polymerase Complex In Vitro

The nucleotide analog sofosbuvir, licensed for the treatment of hepatitis C, recently revealed activity against the Zika virus (ZIKV) in vitro and in animal models. However, the ZIKV genetic barrier to sofosbuvir has not yet been characterized. In this study, in vitro selection experiments were performed in infected human hepatoma cell lines. Increasing drug pressure significantly delayed viral breakthrough (p = 0.029). A double mutant in the NS5 gene (V360L/V607I) emerged in 3 independent experiments at 40–80 µM sofosbuvir resulting in a 3.9 ± 0.9-fold half- maximal inhibitory concentration (IC₅₀) shift with respect to the wild type (WT) virus. A triple mutant (C269Y/V360L/V607I), detected in one experiment at 80 µM, conferred a 6.8-fold IC₅₀ shift with respect to the WT. Molecular dynamics simulations confirmed that the double mutant V360L/V607I impacts the binding mode of sofosbuvir, supporting its role in sofosbuvir resistance. Due to the distance from the catalytic site and to the lack of reliable structural data, the contribution of C269Y was not investigated in silico. By a combination of sequence analysis, phenotypic susceptibility testing, and molecular modeling, we characterized a double ZIKV NS5 mutant with decreased sofosbuvir susceptibility. These data add important information to the profile of sofosbuvir as a possible lead for anti-ZIKV drug development.     

MicroRNAs in Metastasis and the Tumour Microenvironment

Metastasis is the process whereby cancer cells migrate from the primary tumour site to colonise the surrounding or distant tissue or organ. Metastasis is the primary cause of cancer-related mortality and approximately half of all cancer patients present at diagnosis with some form of metastasis. Consequently, there is a clear need to better understand metastasis in order to develop new tools to combat this process. MicroRNAs (miRNAs) regulate gene expression and play an important role in cancer development and progression including in the metastatic process. Particularly important are the roles that miRNAs play in the interaction between tumour cells and non-tumoral cells of the tumour microenvironment (TME), a process mediated largely by circulating miRNAs contained primarily in extracellular vesicles (EVs). In this review, we outline the accumulating evidence for the importance of miRNAs in the communication between tumour cells and the cells of the TME in the context of the pre-metastatic and metastatic niche.     

Polysaccharide‐based membranes loaded with erythromycin for application as wound dressings

In this study, the antibiotic erythromycin (Ery) was incorporated into chitosan (Ch)–alginate (A) and Ch–xanthan (X) membranes with the aim of using them as bioactive wound dressings. Drug incorporation was performed by direct addition (DA) to the polysaccharide mixture and by membrane impregnation in solution (IS). A higher incorporation efficiency was obtained for DA, but higher amounts of drug were loaded into membranes by the IS method (maxima ≈ 2.1 and 0.7 g/g for Ch–X and Ch–A, respectively) because the initial concentration of drug could be higher than that in the DA method. Ery release in phosphate‐buffered saline was slow, reaching about 12 and 32 mg of drug/g of membrane in 60 h for Ch–X and 4 and 16 mg/g for Ch–A by the DA and IS methods, respectively. With formulations prepared with IS, the required therapeutic dosage was reached within 60 h, whereas for those incorporating the drug by DA, prolonged use would be required. Both membrane types behaved as drug reservoirs, providing continuous antibiotic release to the wound site. Formulations with higher drug contents showed effective antibacterial activity against two species of bacteria commonly found in skin lesions, Staphylococcus aureus and Pseudomonas aeruginosa, and were thus potentially capable of protecting the wound site from bacterial attack. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43428.     

Role of π-π interactions and chain flexibility in dispersion and dynamic-mechanical properties of nanocomposites with multiple wall carbon nanotubes

Two polymers of same functional group were used; one with greater chain flexibility, PA 6.6, and the other with two benzene rings in the main chain, PA 6I-6T (aPA), to evaluate how the structure influences on the nanoparticle dispersion homogeneity and on dynamic-mechanical properties. In the aPA nanocomposites, good dispersion and homogeneous distribution were observed for all CNT concentrations. However, PA 6.6 nanocomposites showed agglomerated regions in all formulations. The interfacial energy of the aPA/CNT was five times lower than that of PA6.6/CNT, resulting in greater compatibility in this nanocomposite. An increase of up to 26% was observed with 2.5% of CNT in aPA nanocomposites storage modulus. In the samples with PA 6.6, the increase was at most 5%. Even with greater flexibility of PA 6.6 macromolecules, the π-π interaction between the aPA aromatic rings and CNTs might be the decisive factor for dispersion improvement and positively influence on the dynamic-mechanical properties of these nanocomposites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48195.     

Chemically modified babassu coconut (<Emphasis Type="Italic">Orbignya sp.)</Emphasis> biopolymer: characterization and development of a thin film for its application in electrochemical sensors

The babassu coconut is a plant very abundant in northeast of Brazil and other countries, and any part of plant and fruit becomes residue. In this study, babassu mesocarp (Orbignya sp) (BM) was chemically modified with phthalic anhydride (BMPA) to increase its solubility in an aqueous medium, and thus facilitate its processing in the form of thin films. The reaction of modification of the babassu mesocarp with phthalic anhydride (PA), obtaining BMPA, was confirmed by FTIR, XRD, TG/DTG, Zeta Potential and SEM analysis, from the differences in the bands of the FTIR spectra, increase in crystallinity, new thermal profile, changes in zeta potential value and morphology, respectively. The thin monolayer films of BM and BMPA were produced by the self-assembly monolayer (SAM) technique, and adsorbed onto conductive glass substrates (tin-doped indium oxide, ITO). The electroactive properties of these thin films were evaluated by cyclic voltammetry (CV). BM exhibited a pair redox pair process of +0.57 V(oxidation) and?+?0.19 V (reduction) for BM. In BMPA these redox processes were observed at +0.37 V (oxidation) and 0.24 V vs. ECS (reduction), verifying that both BM and BMPA are electroactive materials that can be used in the construction of sensor platforms, without the necessity of being conjugated with other electroactive materials, such as conductive polymers, metal phthalocyanines, or dyes. Furthermore, under the experimental conditions used, the BMPA presented a more reversible redox process and higher electrochemical stability in comparison to BM. This effect occurs because BMPA has higher solubility in aqueous media, which favors the preparation of films with smaller grain sizes compared to BM films, as observed by Atomic Force Microscopy (AFM). This study showed that BMPA is a new material with potential for applications in electrochemical sensors.

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Graphical abstract Obtaining and modifying babassu mesocarp for the electrochemical studies

     

Extracting Behavioral Data from Physical Descriptions of MEMS for Simulation

The work described here deals with the problems of modeling and simulation for MEMS devices. The eventual goal is to produce a top-down MEMS design system similar to today’s powerful VLSI design systems. In this work a fixed fabrication process (MUMPS) and a fixed layout tool (L-Edit) are chosen. Thus our efforts are concentrated on reliable simulation of designs and eventual comparison with actual fabricated parts. The cantilever beam is chosen as an example of how extraction from a physical layout may be modeled and interfaced with various simulators.     

Solar photocatalytic degradation of real textile effluents by associated titanium dioxide and hydrogen peroxide

The present work investigated the photodegradation of real textile effluents by advanced oxidative process (AOP) using TiO₂/H₂O₂/sunlight system. The procedures were carried out at ambient conditions in March 2005. The results were evaluated by COD reduction concomitant to the increase in inorganic ion concentration (mineralization) and the analysis of the effluent characteristic spectral wavelengths: 228, 254, and 284 nm (simple aromatic compounds), 310 nm (conjugated aromatic compounds), and 390, 450, and 530 (color). As this study is not restricted to the decolorization process, it allows a more reliable evaluation of effluent mineralization. The results indicate that solar radiation is as efficient as or even more efficient than artificial radiation was in previous studies and that it also allows a reduction in effluent treatment operational costs.     

A survey of the current photovoltaic equipment industry in Brazil

The use of renewable alternative sources of energy in the world has been growing in the last few decades due to concerns about dependence on fossil sources and to environmental reasons, related to climatic change and its effects on mankind. Tax and/or financial incentives have been instituted for the population, to have access to renewable source technologies, and for the local equipment industry, to develop more quickly. In Brazil, the PV (photovoltaic) equipment to convert solar into electricity is more often used in low income rural communities, located distant from the grid network, for rural electrification, water pumping and public illumination. However, since there is no currently specific regulatory incentive mechanism for this source in the country, the Brazilian PV equipment industry has not made great advances and the market is largely dominated by multinationals. Against this background, a survey of the current PV equipment industry in Brazil is extremely relevant, especially in the event of a national program development to promote the use of this technology, stimulate the domestic industry and reduce the dependence on imported equipment.