Electrospun nanofibers based on zein and red onion bulb extract (Allium cepa,L.): Volatile compounds,hydrophilicity, and antioxidant activity

Onion is rich in bioactive and volatile compounds with antioxidant activity. However, the pungent odor of volatile compounds (VOCs) released restricts its use. The encapsulation of red onion extract by electrospinning is an alternative to mask this odor and protect its bioactive compounds. The main objective of this study was to encapsulate red onion bulb extract (ROE) in different concentrations into zein nanofibers by electrospinning and evaluate their thermal, antioxidant, and hydrophilicity properties. The major VOC in ROE was 3(2H)-furanone, 2-hexyl-5-methyl. Incorporating ROE into the polymeric solutions increased electrical conductivity and decreased apparent viscosity, rendering nanofibers with a lower average diameter. The loading capacity of ROE on fibers was high, reaching 91.5% (10% ROE). The morphology of the nanofibers was random and continuous; however, it showed beads at the highest ROE concentration (40%). The addition of ROE to the nanofibers increased their hydrophilicity. The nanofibers’ antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl, nitric oxide, and hydroxyl radicals ranged from 32.5% to 57.3%. The electrospun nanofibers have the potential to protect and mask VOCs. In addition, they offer a sustainable alternative to the synthetic antioxidants commonly employed in the food and packaging industry due to their antioxidant activities.     

Ethylene and Propylene Polymerization Using In Situ Supported Me2Si(Ind)2ZrCl2 Catalyst: Experimental and Theoretical Study

Summary: Me₂Si(Ind)₂ZrCl₂ was in situ immobilized onto SMAO and used for ethylene and propylene polymerization in the presence of TEA or TIBA as cocatalyst. The catalytic system Me₂Si(Ind)₂ZrCl₂/SMAO exhibited different behavior depending on the amount and nature of the alkylaluminum employed and on the monomer type. The catalyst activity was nearly 0.4 kg polymer · g cat^?1 · h^?1 with both cocatalysts for propylene polymerization. Similar activities were observed for ethylene polymerization in the presence of TIBA. When ethylene was polymerized using TEA at an Al/Zr molar ratio of 250, the activity was 10 times higher. Polyethylenes made by in situ supported or homogeneous catalyst systems had practically the same melting point (T_m). On the other hand, poly(propylenes) made using in situ supported catalyst systems had a slightly lower T_m than poly(propylenes) made using homogeneous catalyst systems. The nature and amount of the alkylaluminum also influenced the molar mass. The poly(propylene) molar mass was higher when TIBA was the cocatalyst. The opposite behavior was observed for the polyethylenes. Concerning the alkylaluminum concentration, the molar mass of the polymers decreased as the amount of TEA increased. In the presence of TIBA, the polyethylene's molar mass was almost the same, independent of the alkylaluminum concentration, and the poly(propylene) molar mass increased with increasing amounts of cocatalyst. The deconvolution of the GPC curves showed 2 peaks for the homogeneous system and 3 peaks for the heterogeneous in situ supported system. The only exception was observed when TEA was used at an Al/Zr molar ratio of 500, where the best fit was obtained with 2 peaks. Based on the GPC deconvolution results and on the theoretical modeling, a proposal for the active site structure was made.

Molar mass distribution deconvolution of polyethylene prepared with the system Me₂Si(Ind)₂ZrCl₂/SMAO/TIBA with 500 mol/mol of alkylaluminum as cocatalyst.     

Rectilinear ion trap mass spectrometer with atmospheric pressure interface and electrospray ionization source

A rectilinear ion trap (RIT) mass analyzer was incorporated into a mass spectrometer fitted with an electrospray ionization source and an atmospheric pressure interface. The RIT mass spectrometer, which was assembled in two different configurations, was used for the study of biological compounds, for which performance data are given. A variety of techniques, including the use of a balanced rf, elevated background gas pressure, automatic gain control, and resonance ejection waveforms with dynamically adjusted amplitude, were applied to enhance performance. The capabilities of the instrument were characterized using proteins, peptides, and pharmaceutical drugs. Unit resolution and an accuracy of better than m/z 0.2 was achieved for mass-to-charge (m/z) ratios up to 2000 Th at a scan rate of approximately 3000 amu/(charge.s) while reduced scan rates gave greater resolution and peak widths of less than m/z 0.5 over the same range. The mass discrimination in trapping externally generated ions was characterized over the range m/z 190-2000 and an optimized low mass cutoff value of m/z 120-140 was found to give equal trapping efficiencies over the entire range. The radial detection efficiency was measured as a function of m/z ratio and found to rise from 35% at low m/z values to more than 90% for ions of m/z 1800. The way in which the ion trapping capacity depends on the dc trapping potential was investigated by measuring the mass shift due to space charge effects, and it was shown that low trapping potentials minimize space charge effects by increasing the useful volume of the device. The collision-induced dissociation (CID) capabilities of the RIT instrument were evaluated by measuring isolation efficiency as a function of mass resolution as well as measuring peptide CID efficiencies. Overall CID efficiencies of more than 60% were easily reached, while isolation of an ion with unit resolution at m/z 524 was achieved with high rejection (>95%) of the adjacent ions. The overall analytical capabilities of the ESI-RIT instrument were demonstrated with the analysis of a mixture of pharmaceutical compounds using multiple-stage mass spectrometry.     

Dose rate effects on the radiation induced oxidation of polyethylene

The yields and spatial distribution of the products arising from the in source oxidation of 50 μm LDPE films induced by 60-Co gamma radiations and by 300 kev electrons have been investigated as a function of the dose rate. The dose rate was found to have a strong influence on the reaction, the hydroperoxides and carbonyls yields at the lowest gamma dose rate of 0.04 kGy/h being decreased by a factor of about three with increasing the gamma dose rate up to 0.69 kGy/h and by a factor of about 30 when operating at the e-beam dose rate of 1.5 kGy/s. The carbonyls depth concentration profiles, the EPR measurements on radicals intermediates and the experiments of post-irradiation oxidation are consistent with the conclusion that, as far as the gamma irradiation is concerned, the observed dose rate effects cannot be imputed to oxygen diffusion control and/or to the chain branching via hydroperoxides decomposition coupled to the longer times between the initiation events. The hypothesis of the dose rate acting on the kinetic chain length of the radioxidation which in turn implies a substantially uniform distribution of radicals in the amorphous phase attained through spur expansion is proposed.     

Incorporating multiple distance spaces in optimum-path forest classification to improve feedback-based learning

In content-based image retrieval (CBIR) using feedback-based learning, the user marks the relevance of returned images and the system learns how to return more relevant images in a next iteration. In this learning process, image comparison may be based on distinct distance spaces due to multiple visual content representations. This work improves the retrieval process by incorporating multiple distance spaces in a recent method based on optimum-path forest (OPF) classification. For a given training set with relevant and irrelevant images, an optimization algorithm finds the best distance function to compare images as a combination of their distances according to different representations. Two optimization techniques are evaluated: a multi-scale parameter search (MSPS), never used before for CBIR, and a genetic programming (GP) algorithm. The combined distance function is used to project an OPF classifier and to rank images classified as relevant for the next iteration. The ranking process takes into account relevant and irrelevant representatives, previously found by the OPF classifier. Experiments show the advantages in effectiveness of the proposed approach with both optimization techniques over the same approach with single distance space and over another state-of-the-art method based on multiple distance spaces.     

Magnetic-Based Human Tissue 3D Cell Culture: A Systematic Review

Cell-based assays, conducted on monolayer (2D) cultured cells, are an unquestionably valuable tool for biomedical research. However, three-dimensional (3D) cell culture models have gained relevance over the last few years due to the advantages of better mimicking the microenvironment and tissue microarchitecture in vivo. Recent magnetic-based 3D (m3D) cell culture systems can be used for this purpose. These systems are based on exposing magnetized cells to magnetic fields by levitation, bioprinting, or ring formation to promote cell aggregation into 3D structures. However, the successful development of these structures is dependent on several methodological characteristics and can be applied to mimic different human tissues. Thus, a systematic review was performed using Medline (via Pubmed), Scopus, and Web of Science (until February 2022) databases to aggregate studies using m3D culture in which human tissues were mimicked. The search generated 3784 records, of which 25 met the inclusion criteria. The usability of these m3D systems for the development of homotypic or heterotypic spheroids with or without scaffolds was explored in these studies. We also explore methodological differences specifically related to the magnetic method. Generally, the development of m3D cultures has been increasing, with bioprinting and levitation systems being the most used to generate homotypic or heterotypic cultures, mainly to mimic the physiology of human tissues, but also to perform therapeutic screening. This systematic review showed that there are areas of research where the application of this method remains barely explored, such as cancer research.     

Esters from castor oil functionalized with aromatic amines as a potential lubricant

Vegetable oils are very promising alternatives to fossil lubricants due to their abundance, low cost, excellent performance, and environmental friendliness. Due to its multifunctional structure, castor oil is an excellent precursor in the synthesis of new biolubricants. However, it showed poor thermal-oxidative stability and a higher pour point. This study used castor oil fatty acids prepared by transesterification (EHRO), epoxidation (TEPO), and oxirane ring opening with the aromatic amines aniline (ANIL) and p-anisidine (ANIS). The chemical structure of these oils was verified by ¹H and ¹³C NMR analysis, and mass spectrometry. Measurements show that the presence of an aromatic amine increases the viscosity resulting in 172 (ANIL) and 199 (ANIS) cSt at 40°C, but reduces viscosity index to 16 and 1, respectively. In addition, the amine groups can scavenge radicals increasing their thermal and oxidative stability. These products do not oxidize copper, and tribological analysis reveals that ANIS has the lowest torque with wear equivalent to commercial mineral lubricant NH-140.     

Structural and Physicochemical Characteristics of Lintnerized Native and Sour Cassava Starches

The comprehension of the structure of starch granules is important for the understanding of its physicochemical properties. Native and sour cassava starches after being analyzed with respect to their pasting properties and baking expansion capacity, were treated with 2.2 N HCl at 38 °C for a maximum of nine days. The starch granules remaining after lintnerization were analyzed for amylose content and intrinsic viscosity, by X‐ray diffraction, scanning electron microscopy and chromatographic analysis. The results indicated that the acid hydrolysis on all starches occurred in two steps. The first one, with high hydrolysis rate, was characterized by a quick degradation of the amorphous part of the granules whereas the second step, with lower hydrolysis rate, was characterized by a higher resistance of the organized areas of the granules to acid treatment. Most of the amylose chains were found in the amorphous areas of starch granules only a small percentage was involved in the crystalline regions. The microscopic and chromatographic analysis demonstrated that the acid hydrolysis was not able to disrupt the entire granular crystalline structure. Fermented starch showed amylose and/or amylopectin chain fractions resistant to pullulanase, probably due to structural alterations during fermentation.     

Natural Products from Annonaceae as Potential Antichagasic Agents

Chagas disease, a neglected tropical disease, is endemic in 21 Latin American countries and particularly prevalent in Brazil. Chagas disease has drawn more attention in recent years due to its expansion into non-endemic areas. The aim of this work was to computationally identify and experimentally validate the natural products from an Annonaceae family as antichagasic agents. Through the ligand-based virtual screening, we identified 57 molecules with potential activity against the epimastigote form of T. cruzi. Then, 16 molecules were analyzed in the in vitro study, of which, six molecules displayed previously unknown antiepimastigote activity. We also evaluated these six molecules for trypanocidal activity. We observed that all six molecules have potential activity against the amastigote form, but no molecules were active against the trypomastigote form. 13-Epicupressic acid seems to be the most promising, as it was predicted as an active compound in the in silico study against the amastigote form of T. cruzi, in addition to having in vitro activity against the epimastigote form.