Ultrasound-assisted microencapsulation of jackfruit extract in eco-friendly powder particles: characterization and antiproliferative activity

The aim of the article was to develop stable and safe eco-friendly microcapsules and evaluate their physicochemical properties and their efficiency to protect a jackfruit extract. Eco-friendly microcapsules were produced by ultrasound and spray drying using only three safe ingredients: sucrose ester (SE), miglyol and maltodextrin (DE = 10). Some physicochemical properties, particle morphology, FT-IR, differential scanning calorimetry and antiproliferative activity were determined for microcapsules loaded or not with the jackfuit extract. The results revealed that the encapsulation process by spray drying produced stable microcapsules, with adequate physicochemical and fluid properties for a powder product. The cell viability on the proliferation of M12.C3.F6 cell line was not affected by powder microcapsules without jackfruit extract, indicating that capsules are not toxic for these cells. However, microcapsules with jackfruit extract (100 μg/ml) were able to inhibit significantly the proliferation of M12.C3.F6 cells. These microcapsules can be used for the protection of different compounds sensitive to light, oxygen and/or heat and displaying a very low aqueous solubility.     

Polyterephthalates made from Ethylene glycol, 1,4‐cyclohexanedimethanol,and isosorbide

Three series of terephthalate polyesters (copolyesters and terpolyesters) containing 70, 80, and 90 mol % of ethylene glycol respectively, 1,4‐cyclohexanedimethanol (CHDM) and isosorbide in varying ratios, were synthesized by melt polycondensation. It was found that only ～75 mol % of the feeding isosorbide was incorporated in the resulting polyesters and that their content in diethylene glycol oscillated between 2 and 4 mol %. The polyesters had weight‐average molecular weights in the 25,000–33,000 g mol^?1 range and polydispersities between 2 and 2.5. The combined ¹H and ¹³C NMR analysis revealed that the microstructure of all these polyesters was at random. They showed good thermal stability with decomposition temperatures above 400 °C. Their glass‐transition temperatures were observed to increase with the content in cyclic diols, this effect being more pronounced when isosorbide was the replacing comonomer. Only the series containing 90 mol % of ethylene terephthalate units was able to crystallize upon cooling from the melt. Compared isothermal crystallizations revealed that isosorbide was more effective than CHDM in repressing the crystallizability of PET. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Amphiphilic block glycopolymers via atom transfer radical polymerization: Synthesis,self‐assembly and biomolecular recognition

In this work the synthesis of poly(butyl acrylate)‐b‐poly(2‐{[(D ‐glucosamin‐2‐N‐yl)carbonyl]oxy}ethyl methacrylate) (PBA‐b‐PHEMAGl) diblock glycopolymer and poly(2‐{[(D ‐glucosamin‐2‐N‐yl)carbonyl]oxy}ethyl methacrylate)‐b‐poly(butyl acrylate)‐b‐poly(2‐{[(D ‐glucosamin‐2‐N‐yl)carbonyl]oxy}ethyl methacrylate) (PHEMAGl‐b‐PBA‐b‐PHEMAGl) was performed via atom transfer radical polymerization. Monofunctional and difunctional poly(butyl acrylate) macroinitiators were used to synthesize the well‐defined diblock and triblock glycopolymers by chain extension reaction with the glycomonomer HEMAGl. The self‐assembly of these glycopolymers in aqueous solution was studied by dynamic light scattering and transmission electron microcopy, showing the coexistence of spherical micelles and polymeric vesicles. In addition, the biomolecular recognition capacity of these micelles and vesicles, containing glucose moieties in their coronas, was investigated using the lectin Concanavalin A, Canavalia Ensiformis, which specifically interacts with glucose groups. The binding capacity of Concanavalin A with glycopolymer is influenced by the copolymer composition, increasing with the length of HEMAGl glycopolymer segment in the block copolymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Polybenzoxazines from renewable diphenolic acid

The novel benzoxazine monomers, DPA‐Bz and MDP‐Bz from renewable diphenolic acid (DPA), which mimics the structure of bisphenol A (BPA), were synthesized by traditional approaches. The structure and purity of the monomers was confirmed by FTIR, ¹H NMR, and ¹³C NMR spectra. The thermally activated polymerization of the MDP‐Bz and DPA‐Bz afforded thermosetting polybenzoxazines with higher T_g's, 270 °C and 208 °C respectively, and higher crosslinking density compared to BPA‐Bz, due to the transesterification or esterification reactions occurred during curing process. These reactions are in accordance with the number of independent reactions determined analyzing by SVD the chemical rank of the IR spectra data matrices recorded along the homopolymerization reactions monitored at 200 °C. Spectral and concentration profiles of the active chemical species involved in these processes were obtained by MCR‐ALS. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Characterization of natural cellulosic fibers from Yucca aloifolia L. leaf as potential reinforcement of polymer composites

Cellulose - In this work lignocellulosic fibers were obtained from Yucca aloifolia L. leaves and their chemical, morphological, thermal and mechanical properties were studied. The fibers were...     

Characterization of reaction products of iron and iron salts and aqueous plant extracts

The complexes formed in aqueous solution as a result of a reaction of iron and iron salts (Fe²⁺ and Fe³⁺) and some plant extracts were analyzed using Mössbauer spectroscopy and Fourier transform infrared. The extracts were obtained from Opuntia elatior mill., Acanthocereus pentagonus (L.) Britton, Mimosa tenuiflora, Caesalpinia coriaria (Jacq.) Willd., Bumbacopsis quinata (Jacq.) Dugand and Acacia mangium Willd., plants growing wildly in different zones of the Isthmus of Panama. Results suggest the formation of mono- and bis-type complexes, and in some cases, the occurrence of a redox reaction. The feasibility of application of the studied extracts as atmospheric corrosion inhibitors is discussed.     

Geometrothermodynamics of a Charged Black Hole of String Theory

The thermodynamics of the Gibbons–Maeda–Garfinkle–Horowitz–Strominger charged black hole from string theory is reformulated within the context of the recently developed formalism of geometrothermodynamics. The geometry of the space of equilibrium states is curved, but we show that the thermodynamic curvature does not diverge at the phase transition point expected when the black hole solution becomes a naked singularity. This provides a counterexample to the conventional notion that such a divergence signals the occurrence of a second-order phase transition.     

Thermal analysis of the combustion of charcoals from Eucalyptus dunnii obtained at different pyrolysis temperatures

DSC and TG/DTA were used to study charcoals obtained from eucalyptus wood at different pyrolysis temperatures, as well as the exchanged energy, and the transformations involved during the pyrolysis process. Charcoals DSC curves showed two exothermic peaks, at ~610 and ~750 K. The first peak was squashed for those charcoals obtained at higher final pyrolysis temperatures, and it disappeared in the charcoals obtained at 873 and 923 K. The second peak intensity increased and its location changed at the higher temperatures. Charcoal characterization showed a rise of heat values with the pyrolysis temperature.     

Silica nano-particles produced by worms through a bio-digestion process of rice husk

It is reported the production and characterization of silica nano-particles by Californian-red worms through a bio-digestion process of rice husk; the rice husk contains, naturally, high concentrations of silica (22%). The worms were fed gradually with rice husk and water during 5 months to clean the worm’s digestive system from other types of food. The humus was collected, dried at room temperature, pH neutralized and calcined at different temperatures (500, 600 and 700 °C) to remove the organic matter. The calcined humus was digested to remove traces of inorganic compounds. The size of the silica particles was in the range from 55 to 250 nm depending on calcination temperatures. The efficiency in the production of the particles was 88%. These results were compared with those obtained using other agro-industrial wastes that contain silica: coffee (12%) and cane (8%) husk. The samples were characterized by XRD, FTIR, EDS, DLS, SEM and TEM.