Polymeric biocomposites of poly (butylene adipate-co-terephthalate) reinforced with natural Munguba fibers

In this work, polymeric biocomposites of poly (butylene adipate-co-terephthalate), PBAT, were reinforced with Munguba fibers (Pseudobombax munguba). This tree is found in great abundance in the marshy areas of the Amazon forest. The motivation for using this fiber in polymer composites comes from the fact that although research for this fiber has not been reported in the scientific literature, it is commonly used by the local population because its bark is strong and flexible. Most important is that the extraction of Munguba fibers does not damage the supplier tree because as it is extracted from the bark, its regeneration starts as it is removed. The fibers were chemically treated by mercerization/acetylation and evaluated by Fourier transform infrared spectroscopy, thermogravimetric analysis and tensile tests. The Munguba fiber presented mechanical properties similar to those of other natural fibers traditionally used in composites, and the chemical treatment provided improvements of its thermal stability and stiffness. The biocomposites showed a better elastic modulus in relation to the pure PBAT. The addition of fibers caused changes in the T _g, T _m and T _c of PBAT as observed by differential scanning calorimetry analysis. The Russel, Halpin-Tsai and Maxwell models were employed to provide the theoretical elastic modulus of the biocomposites.     

Characterization of Biocatalysts Prepared with Thermomyces lanuginosus Lipase and Different Silica Precursors,Dried using Aerogel and Xerogel Techniques

The use of lipases in industrial processes can result in products with high levels of purity and at the same time reduce pollutant generation and improve both selectivity and yields. In this work, lipase from Thermomyces lanuginosus was immobilized using two different techniques. The first involves the hydrolysis/polycondensation of a silica precursor (tetramethoxysilane (TMOS)) at neutral pH and ambient temperature, and the second one uses tetraethoxysilane (TEOS) as the silica precursor, involving the hydrolysis and polycondensation of the alkoxide in appropriate solvents. After immobilization, the enzymatic preparations were dried using the aerogel and xerogel techniques and then characterized in terms of their hydrolytic activities using a titrimetric method with olive oil and by the formation of 2-phenylethyl acetate in a transesterification reaction. The morphological properties of the materials were characterized using scanning electron microscopy, measurements of the surface area and pore size and volume, thermogravimetric analysis, and exploratory differential calorimetry. The results of the work indicate that the use of different silica precursors (TEOS or TMOS) and different drying techniques (aerogel or xerogel) can significantly affect the properties of the resulting biocatalyst. Drying with supercritical CO₂ provided higher enzymatic activities and pore sizes and was therefore preferable to drying, using the xerogel technique. Thermogravimetric analysis and differential scanning calorimetry analyses revealed differences in behavior between the two biocatalyst preparations due to the compounds present.     

Lamellar mono-amidosil hybrids doped with Rhodamine (B) methyl ester perchlorate

Ordered mono-amide cross-linked alkyl/siloxane hybrids (mono-amidosils) incorporating a Rhodamine (B) methyl ester perchlorate dye (Rh(B)CH₃ClO₄) have been synthesized through the sol–gel process and self-directed assembly. The host hybrid matrix m-A(14) is a lamellar bilayer hierarchically structured hybrid composed of short methyl-capped alkyl chains grafted to a siliceous framework through amide groups. At low dye concentration [n = 20, where n is the molar ratio of amide groups per Rh(B)CH₃ClO₄] a new lamellar structure with higher interlamellar distance than that of m-A(14) is formed, whereas at higher dye content (n = 5) this new lamellar structure coexists with that of m-A(14). The efficient encapsulation of Rh(B)CH₃ClO₄ provided by m-A(14) via hydrogen bonding interactions ensured the complete dissolution of the dye and induced a blue shift of the emission of the dye with respect to that of the isolated state, leading to an increase in the quantum yield from values below 0.01 % (measured for the isolated dye) to 4 % at n = 20. The formation of non-fluorescent H-type dimers in the sample with n = 5 accounts for the reduction of the quantum yield. The incorporation of Rh(B)CH₃ClO₄) into m-A(14) was clearly beneficial from the standpoint of the dye’s photostability, allowing to suppress photobleaching during the first 4 h. An intensification of the emission intensity by 50 and 25 % for the emission centered at 600 and 645 nm resulted, respectively, at n = 20.     

Terroir Effect on the Phenolic Composition and Chromatic Characteristics of Mencía/Jaen Monovarietal Wines: Bierzo D.O. (Spain) and Dão D.O. (Portugal)

‘Mencía’/‘Jaen’ it’s an important red grape variety, exclusive of the Iberian Peninsula, used in wine production namely in Bierzo D.O. and Dão D.O., respectively. This work evaluates the effect of the two different “terroirs” on the phenolic composition and chromatic characteristics of ‘Mencía’/‘Jaen’ monovarietal wines produced at an industrial scale in the same vintage. Using Principal Component Analysis (PCA), Partial Least Squares-Discrimination Analysis (PLS-DA), and Orthogonal PLS-DA (OPLS-DA) it was found that peonidin-3-coumaroylglucoside, petunidin-3-glucoside, malvidin-3-coumaroylglucoside, peonidin-3-glucoside, malvidin-3-acetylglucoside, malvidin-3-glucoside, and ferulic acid were the phenolic compounds with the highest differences between the two regions. PLS regression allowed to correlate the differences in lightness (L*) and redness (a*) of wines from ‘Jaen’ and ‘Mencía’ to differences in colored anthocyanins, polymeric pigments, total pigments, total anthocyanins, cyanidin-3-acetylglucoside, delphinidin-3-acetylglucoside, delphinidin-3-glucoside, peonidin-3-coumaroylglucoside, petunidin-3-glucoside and malvidin-3-glucoside in wines, and the colorless ferulic, caffeic, and coutaric acids, and ethyl caffeate. The wines a* values were more affected by colored anthocyanins, ferulic acid, total anthocyanins, delphinidin-3-acetylglucoside, delphinidin-3-glucoside and petunidin-3-acetylglucoside, and catechin. The positive influence of ferulic acid in the a* values and ferulic, caffeic, coutaric acids, and ethyl caffeate on the L* values can be due to the co-pigmentation phenomena. The higher dryness and lower temperatures during the September nights in this vintage might explain the differences observed in the anthocyanin content and chromatic characteristics of the wines.     

Bioactive Properties and Phenolic Compound Profiles of Turnip-Rooted,Plain-Leafed and Curly-Leafed Parsley Cultivars

Petroselinum crispum Mill., Fuss., is a culinary vegetable used as an aromatic herb that garnishes and flavours a great variety of dishes. In the present study, the chemical profiles and bioactivities of leaf samples from 25 cultivars (three types: plain- and curly-leafed and turnip-rooted) from this species were assessed. Seven phenolic compounds were identified in all the varieties, including apigenin and kaempherol derivates. Apigenin-O-pentoside-O-hexoside was the major compound in all the tested parsley types (20, 22 and 13 mg/g of extract, respectively) and responsible for its excellent antioxidant activity, also investigated in this study. Antimicrobial activities were also explored, and the results revealed a good bioactivity against specific tested pathogens, such as bacteria and fungi. In conclusion, the leaves of all the types of P. crispum are a good source of natural bioactive compounds that confer health benefits, and thus, they should be part of a balanced and diversified diet.     

Contribution of CuxO distribution,shape and ratio on TiO2 nanotubes to improve methanol production from CO2 photoelectroreduction

Many studies are focused on the development of materials for converting carbon dioxide into multicarbon oxygenates such as methanol and ethanol, because of their higher energy density and wider applicability. In this work, TiO₂ nanotubes (NT/TiO₂) were modified with Cu_xO nanoparticles in order to investigate the contribution of different ratio of Cu₂O/CuO and its distribution over NT/TiO₂ for CO₂ photoelectro-conversion to methanol. The photoelectrodes were built by anodization process to obtain NT/TiO₂ layer, and the decoration with Cu_xO hybrid system was carried out by electrodeposition process, using Na₂SO₄ or acid lactic as electrolyte, followed by annealing at different temperatures. X-ray photoelectron spectroscopy analysis revealed the predominance of Cu⁺¹ and Cu⁺² at 150 °C and 300 °C, respectively. X-ray diffraction and scanning electron microscopy indicated that under lactic acid solution, the oxide nanoparticles exhibited small size, cubic shape, and uniform distribution on the nanotube wall. While under Na₂SO₄ electrolyte, large nanoparticles with two different morphologies, octahedral and cubic shapes, were deposited on the top of the nanotubes. All modified electrodes converted CO₂ in methanol in different quantities, identified by gas chromatograph. However, the NT/TiO₂ modified with CuO/Cu₂O (80:20) nanoparticles using lactic acid as electrolyte showed better performance in the CO₂ reduction to methanol (0.11 mmol L⁻¹) in relation to the other electrodes. In all cases, a blend among the structures and nanoparticle morphologies were achieved and essential to create new site of reactions what improved the use of light irradiation, minimization of charge recombination rate and promoted high selectivity of products.

     

Flow-through amperometric methods for detection of the bioactive compound quercetin: performance of glassy carbon and screen-printed carbon electrodes

Journal of Solid State Electrochemistry - Rapid methods using batch injection analysis (BIA) with amperometric detection were developed for the determination of quercetin extracted from the...     

Sustainability in Skin Care: Incorporation of Avocado Peel Extracts in Topical Formulations

The avocado peel is an agro-industrial by-product that has exhibited a massive increase in its production in the last few years. The reuse and valorisation of this by-product are essential since its disposal raises environmental concerns. In the present study, ethanolic extracts of avocado peels of the Hass variety were obtained, for three extraction times (1.5 h, 3 h and 4 h) and analysed for their antioxidant and antibacterial properties. Antioxidant evaluations of the extracts revealed that the extraction time of 1.5 h exhibited the best results amongst the three, with a DPPH inhibition percentage of 93.92 ± 1.29 and an IC₅₀ percentage, the necessary concentration of the extract to inhibit 50% of DPPH, of 37.30 ± 1.00. The antibacterial capacity of the extracts was evaluated and it was revealed that they were able to inhibit the growth and development of bacteria of the Staphylococcus family. The obtained extract was incorporated in two types of cosmetic formulations (oil-in-water and water-in-oil) and their stability was evaluated and compared with formulations containing synthetic preservatives (BHT and phenoxyethanol). The results of the stability evaluation suggest that the avocado peel extract has the potential to be incorporated in both types of emulsions, acting as an antioxidant and antibacterial agent, proving it to be a viable option to reduce/replace the use of synthetic preservatives. Furthermore, the avocado peel extract proved to be more effective and stable in oil-in-water emulsions. These results highlight the possibility of obtaining sustainable cosmetics, significantly reducing the negative impacts on the environment by the incorporation of extracts sourced from the avocado peel, an interesting source of phenolic compounds, an abundant and low-cost by-product.