464 research outputs found

    Apiaceae subfamily Apioideae in Madagascar

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    An account of the Apiaceae (Umbelliferae) for the Flore de Madagascar et des Comores (Paris) has recently been completed and submitted for publication (Sales and Hedge 2004). The flora account deals with 15 genera and 31 species in the subfamilies Hydrocotyloideae, Saniculoideae and Apioideae; some of the species are globally widespread and/or doubtfully native. Five new species will be described in Peucedanum (2), Phellolophium (1) and Pimpinella (2). Here, we concentrate on subfam. Apioideae, draw attention to some features of special interest and provide a checklist of the native 11 genera and 20 species currently known to occur in Madagascar

    A simple approach for the determination and characterization of ternary phase diagrams of aqueous two-phase systems composed of water, poly(ethylene) glycol and sodium carbonate

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    In this work, an experimental protocol to determine liquid-liquid phase diagrams of aqueous two-phase systems (ATPS) in a chemical engineering course is described. Throughout this laboratory set of experiments, students will determine liquid-liquid ternary phase diagrams, comprising the solubility curves, tie-lines, tie-line lengths and critical points, for systems composed of poly(ethylene) glycol, sodium carbonate and water. Furthermore, students will apply the NRTL (Non-Random Two Liquid) model to fit the experimental tie-lines.publishe

    Enhancing artemisinin solubility in aqueous solutions: searching for hydrotropes based on ionic liquids

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    Artemisinin is a sesquiterpenoid lactone peroxide, known for its potent antimalarial activity that can be extracted from Artemisia annua L. This compound is only sparingly soluble in water, making its extraction using environmental-friendly and non-toxic aqueous solvents difficult. In the attempt to overcome this limitation, hydrotropes, which are a class of compounds that can assist in increasing the solubility of hydrophobic solutes in water, were investigated in this work. In particular, the hydrotropic capability of ionic liquids (ILs) on the aqueous solubility of artemisinin was studied. The effects of IL concentration and anion nature of 1-butyl-3-methylimidazolium-based ILs on the solubility of artemisinin at 303.2 K in water were evaluated. It is here shown the excellent capacity of ILs containing thiocyanate or dicyanamide anions to enhance the solubility of artemisinin in aqueous media, with a magnitude comparable to that obtained with the best organic solvents. Furthermore, solvatochromic parameters of the ILs aqueous solutions were also measured and combined with COSMO-RS and the cooperative hydrotropy model to establish relations between the artemisinin solubility enhancement and the solvent characteristics. The solubility enhancement of artemisinin is favored by the apolarity of the medium and the lower hydrogen-bond acceptor character of the hydrotrope.This work was developed within the scope of the projects CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, CIMO-Mountain Research Center, UIDB/00690/2020, all financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. Isabela Sales and Silvana Mattedi thanks the finantial support from CAPES and CNPq/Brazil (CAPES: Proc. 88881.189075/2018-01 and 88887.494428/2020-00. CNPq: Grant 303089/2019-9 and Proc.438036/2018-2).info:eu-repo/semantics/publishedVersio

    Protein-olive oil-in-water nanoemulsions as encapsulation materials for curcumin acting as anticancer agent towards MDA-MB-231 cells

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    The sustainable cellular delivery of the pleiotropic drug curcumin encounters drawbacks related to its fast autoxidation at the physiological pH, cytotoxicity of delivery vehicles and poor cellular uptake. A biomaterial compatible with curcumin and with the appropriate structure to allow the correct curcumin encapsulation considering its poor solubility in water, while maintaining its stability for a safe release was developed. In this work, the biomaterial developed started by the preparation of an oil-in-water nanoemulsion using with a cytocompatible copolymer (Pluronic F 127) coated with a positively charged protein (gelatin), designed as G-Cur-NE, to mitigate the cytotoxicity issue of curcumin. These G-Cur-NE showed excellent capacity to stabilize curcumin, to increase its bio-accessibility, while allowing to arrest its autoxidation during its successful application as an anticancer agent proved by the disintegration of MDA-MB-231 breast cancer cells as a proof of concept

    Supported ionic liquids as customizable materials to purify immunoglobulin G

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    Over the past few years, antibodies such as immunoglobulin G, IgG, have increased their market share as alternative therapeutics. However, their production at high purity levels is still costly due to the absence of a cost-effective platform for their recovery and purification from the complex biological media in which they are produced. This work describes, for the first time, that materials modified with ionic liquids (ILs) can be designed for the effective capture and purification of antibodies from complex matrices, allowing both the selective adsorption of IgG or the selective adsorption of other proteins present in the media. The best results correspond to IgG with 59 % of yield and 84 % of purity in the aqueous solution, and IgG with 76 % of yield and 100 % of purity on the surface of one SIL due to the selective adsorption of IgG from human serum. The best conditions and materials were then applied to other IgG-containing matrices, namely rabbit serum and Chinese hamster ovary (CHO) cell culture supernatants, proving the robustness of the developed strategy. Furthermore, it is demonstrated that the secondary structure of IgG is preserved during the purification process and that these antibodies remain biologically active. In summary, it is shown that by only changing the IL chemical structure at the material surface it is possible to selectively adsorb IgG or to adsorb other proteins leaving IgG in solution. These findings prove that SILs are customizable materials with future potential to act in the flow-through or bind-andelute modes. Therefore, SILs can be envisioned as potential chromatographic columns capable of substituting the high-cost commercial chromatographic columns based on biological ligands currently used to purify IgG.publishe

    Ionic liquid-mediated recovery of carotenoids from the bactris gasipaes fruit waste and their application in food-packaging chitosan films

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    In this work, a process for the extraction and purification of carotenoids from the fruit Bactris gasipaes was developed. Ethanolic and aqueous solutions of ionic liquids (ILs) and surfactants were evaluated on the extraction of these pigments. Thus, we developed an optimized sustainable downstream process mediated by the best solvent with further isolation of the carotenoids and the recyclability of the IL used. The process was characterized not only in terms of efficiency but also regarding its environmental impact. The recyclability of the solvents as well as the high efficiency (maximum yield of extraction of carotenoids = 88.7 ± 0.9 μgcarotenoids·gdried biomass–1) and the low environmental impact of the integrated process developed in this work were demonstrated. In the end, in order to incorporate functional activity for an alternative food-packaging material, carotenoids were successfully applied on the preparation of chitosan-based films with excellent results regarding their mechanical parameters and antioxidant activity.publishe

    Cations extraction of sandy-clay soils from Cavado valley, Portugal, using sodium salts solutions

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    Cases of contamination by metals in the water wells of the Cavado Valley in north-west Portugal can be attributed to the heavy leaching of clay soils due to an excess of nitrogen resulting from the intensive use of fertilisers in agricultural areas. This work focuses on the natural weathering characteristics of soils, particularly the clay material, through the study of samples collected near the River Cavado. Samples taken from various sites, after physico-chemical characterisation, were subjected to clay dissolution tests, using sodium salts of different ionic forces, to detect the relationship between certain physico-chemical parameters of water, such as pH, nitrate, chloride and sulphate content, in the dissolution of clay and the subsequent extraction of such cations as Al, Fe and K. In acidic sandy clay soils, the mineralogical composition of which was characterised by a predominance of quartz, micas, kaolinite and K-feldspars, decreases of the clay material/water pH ratio increases dissolution of the micaceous and K-feldspars phases. The presence of nitrates in the aqueous solution apparently advanced the extraction of all three cations Al, Fe and K. The specific surface area of the clay material showed a significant correlation with the main kinetic parameters of cation extraction.Têm ocorrido casos de contaminações de águas de poços, por metais, no vale do Rio Cávado, região noroeste de Portugal. A princípio, poderiam ser explicáveis pela elevada lixiviação dos solos arenoargilosos da região, quando da prática de adubações intensivas de nitrogênio em áreas agrícolas. Assim, estudaram-se as características do intemperismo natural dos solos, particularmente da fração argila, característica da margem norte do rio Cávado. Coletaram-se amostras de vários locais, que foram submetidas, após caracterização físico-química, a ensaios de dissolução a partir de soluções de sais de sódio com diferentes forças iônicas. O objetivo foi observar as relações de determinados parâmetros físico-químicos da água, tais como: pH, nitratos, cloretos e sulfatos na dissolução das argilas e a conseqüente extração de espécies químicas tais como Al, K e Fe. Para solos areno-argilosos, ácidos, cuja composição mineralógica se caracteriza por um predomínio de quartzo, micas, caulinita e feldspato-K, o abaixamento do pH da suspensão solo/água promove a solubilização das fases micáceas e feldspáticas. A presença do nitrato nas soluções aquosas promoveu aparentemente a extração de todos os três cátions: Al, K e Fe. O efeito da área superfícial específica das partículas dos solos condicionou fortemente vários dos parâmetros cinéticos estudados relativos à extração dos cátions.(undefined

    Modeling of the binodal curve of ionic liquid/salt aqueous systems

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    Ionic Liquid-based Aqueous Two Phase Systems (ILATPS) are an innovative technique to separate biomolecules that combines the advantages of liquid–liquid extraction and hydrophilic ionic liquids. Most ILATPS are based on ionic liquids and conventional inorganic salts, and the phase envelope, described by the binodal curve, is usually modeled by empirical equations that are used to determine the phase compositions and assess the ionic liquid recyclability. However, these empirical equations may provide a poor extrapolation ability or low accuracy at the extreme regions of the binodal curve or suffer from problems of convergence. Therefore, the aim of this work is the analysis of the binodal curve equations, comparing the models reported in the literature to describe ILATPS and proposing alternative equations to improve accuracy or to reduce the mathematical complexity. For this purpose, a database compiling binodal experimental data of 100 ILATPS has been built, so that the analysis could make it possible to obtain representative conclusions for all these systems. Several models were developed, and different statistical criteria were used to assess the advantages and disadvantages of each one of these models for the binodal curve. The results show that, when accuracy is critical, a proposed model with just an additional parameter reduced more than 25% the residual mean squared error (RMSE) with respect to the commonly used equation, without losing the statistical significance of the parameters. For complex problems where an explicit equation in both the concentration of ionic liquid and of salt is needed, the use of an explicit model developed with 3 adjusted parameters that kept high accuracy (R2 > 0.996 and RMSE < 0.66) is proposed. Finally, the analysis also revealed that a fitting method based on the minimization of relative errors is recommended to increase the accuracy of the binodal curve at high salt concentrations, which is the crucial region for assessing the recyclability of the ionic liquid.This work was developed in the scope of the project CICECO Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and co-financed by FEDER under the PT2020 Partnership Agreement. The authors also acknowledge FCT for the Post-doctoral grant SFRH/BPD/79263/2011 of S.P.M. Ventura

    The antagonist and synergist potential of cholinium-based deep eutectic solvents

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    The design of environmentally friendlier solvents has gained increasing relevance in the last decade. Deep eutectic solvents (DES) have recently emerged, with advantages like low-cost and putative lower environmental impact. However, information about DES toxicity is still scarce. This work aims to contribute to profiling the ecotoxicity of DES based on cholinium chloride ([Chol]Cl). Six DES were addressed, combining [Chol]Cl (as hydrogen bond acceptor - HBA) with ethylene glycol, glycerol, 1,2-propanediol, propionic acid, 1-propanol, and urea as hydrogen bond donors (HBD), in different molar ratios. The Microtox® Acute Toxicity Test, was used for assessing their toxicity towards the marine bacteria Allivibrio fischeri . Because the dissociation of DES in water is expected, analysis appraising the mixtures toxicity theory should be considered, which is a step forward in this field. This analysis suggested that [Chol]Cl and all HBD with the exception of propionic acid:[Chol]Cl 1:2 and 4:1 behave antagonistically, which is contrary to what has been suggested previously. The most extreme cases are Urea:[Chol]Cl and 1-Propanol:[Chol]Cl, with EC50 values higher than their starting materials dosed singly, configuring very promising and biocompatible alternative solvents. Toxicity was found to be dependent on DES composition, as well as on molar proportions of the starting materials.publishe
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