The influence of sintering process and atmosphere on the non-ohmic properties of SnO2 based varistor

The non-ohmic properties of the 98.95% SnO₂ + 1.0%,CoO + 0.05%,Nb₂O₅ (all in mole%) system, as well as the influence of sintering temperature and atmosphere on these properties, were characterized in this study. The maximum non-linear coefficient ( = 32) was obtained for a sintering temperature of 1300°C in an oxygen atmosphere and this maximum is associated with the presence of O in SnO₂ grain boundaries, as interface defects. Experimental results also indicate thermionic-type conduction mechanisms, which are associated with the potential barrier of Schottky or Poole–Frenkel types.     

Preparation of PLLA/PDLA stereocomplexes using a novel initiator based on Mg(II) and Ti(IV) alkoxides

Herein we describe the obtention of polylactide stereocomplexes using a novel initiator system comprising Mg(II) and Ti(IV) centers. The stereocomplexes were successfully prepared using two different routes: by PDLA and PLLA co‐precipitation from chloroform solutions and two‐step diblock copolymerization. For the PDLA/PLLA mixing procedure, individual homochiral polymers were prepared in solution at different monomer/initiator ratios; whereas, the PLA stereoblock was prepared employing one‐pot sequential polymerization of both chiral monomers. The products analyzed by WAXD showed the characteristic stereocrystal reflections while the high melting temperatures found in the DSC runs confirmed the formation of PLA stereocomplexes in both cases. Surprisingly, one of the stereocomplexes showed a second endothermic event at 250.1°C and to our knowledge this is the highest melting temperature reported for PLA stereocomplexes till date. These results point to the discovery of an effective initiator based on low toxicity metals for the preparation of biodegradable materials with interesting thermal properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40771.     

Mycoflora in commercial pet foods

This article reports on the identification of mycoflora of 21 dry pet foods (12 belonging to dogs and 9 to cats) that corresponded to 8 commercial brands made in Argentina and imported. The isolation frequency and relative density of the prevalent fungal genera are compared too. Ten genera and fungi classified as Mycelia sterilia were identified. The predominant genera were Aspergillus (62%), Rhizopus (48%), and Mucor (38%). The most prevalent among Aspergillus was Aspergillus flavus followed by Aspergillus niger and Aspergillus terreus. The predominant Mucor was Mucor racemosus followed by Mucor plumbeus and Mucor globosus. The moisture content of these foods ranged from 5.6 to 10.0% and from 7.2 to 9.9% for dog and cat foods, respectively. A greater moisture content in food for the senior category (9.5 +/- 0.2) was observed only in comparison to adult and kitten/puppy. If the moisture content can be maintained at these levels, mold growth would be prevented or at least it would remain at an insignificant level. Some genera and species isolated and identified from the foods analyzed are potentially producing toxins, which are known as mycotoxins. This involves a risk for animal health.     

Effect of MWNTs concentration and cooling rate on the morphological,structural, and electrical properties of non‐isothermally crystallized PEN/MWNT nanocomposites

The effect of multiwall carbon nanotubes (MWNT) concentration and cooling rate on the morphological, structural and electrical properties of non‐isothermally crystallized Poly(ethylene naphthalate) nanocomposites (PEN/MWNT) was studied. PEN/MWNT nanocomposites containing 1 and 2 wt % of nanotubes were prepared by melt blending in a mini twin screw extruder. Nanocomposite samples with different degree of crystallinity (X_c) were obtained via non‐isothermally crystallization at cooling rates of 2, 10, 20, and 300°C min^?1. In this study it was demonstrated that carbon nanotubes and cooling rate strongly influence morphological and structural characteristics of PEN. Calorimetric results showed that the peak crystallization temperature (T_c) of PEN nanocomposites was increased ～9° through heterogeneous nucleation with respect to pure PEN. X‐ray diffraction revealed that carbon nanotubes modify the crystalline structure of PEN favoring the formation of β‐crystals, and this effect increases with the nanotubes content. On the basis of X‐ray scattering analysis, the variation of lamellar thickness revealed that nanotubes promote the formation of lamellar crystals with average thickness of 20 nm at different cooling rates. These structural and morphological changes play an important role on the electrical properties of nanocomposites. It was found that higher concentration of nanotubes and crystallinity promotes electrical conductivity of nanocomposites in the order of semiconductors (until 1 × 10^?4 S cm^?1) as well as permittivity of 20 at different tested frequencies. This may due to the interconnected networks of nanotubes throughout the crystalline structure formed in PEN nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41765.     

Enhancement of microbial oil production by alpha-linolenic acid producing Yarrowia lipolytica strains QU22 and QU137

Microbial oils enriched in essential polyunsaturated fatty acids can be used as nutritional complements. In order to improve the lipid yields and lipid profiles of 2 Yarrowia lipolytica strains, the effects of medium components and culture conditions were investigated using shake flasks. Under optimized conditions (cultivation for 3 days at 25oC and 150 rpm, using peptone as a nitrogen source and glucose as a carbon source), the biomass, lipid yield, and lipid content reached 6.75 g/L, 3.48 g/L, and 51.55% for Y. lipolytica QU22, and 6.85 g/L, 3.52 g/L, and 51.38% for Y. lipolytica QU137, respectively. Using a shaking speed of 150 rpm, unsaturated fatty acids constituted 87.96% (QU22) and 87.08% (QU137) of the total lipids produced by these strains, with 9.52 and 7.86% of alpha-linolenic acid, respectively. The strains are suitable candidates for fermentation processes involving essential polyunsaturated fatty acid (PUFA) production.     

Renin-Angiotensin System in Huntington′s Disease: Evidence from Animal Models and Human Patients

The Renin-Angiotensin System (RAS) is expressed in the central nervous system and has important functions that go beyond blood pressure regulation. Clinical and experimental studies have suggested that alterations in the brain RAS contribute to the development and progression of neurodegenerative diseases. However, there is limited information regarding the involvement of RAS components in Huntington’s disease (HD). Herein, we used the HD murine model, (BACHD), as well as samples from patients with HD to investigate the role of both the classical and alternative axes of RAS in HD pathophysiology. BACHD mice displayed worse motor performance in different behavioral tests alongside a decrease in the levels and activity of the components of the RAS alternative axis ACE2, Ang-(1-7), and Mas receptors in the striatum, prefrontal cortex, and hippocampus. BACHD mice also displayed a significant increase in mRNA expression of the AT1 receptor, a component of the RAS classical arm, in these key brain regions. Moreover, patients with manifest HD presented higher plasma levels of Ang-(1-7). No significant changes were found in the levels of ACE, ACE2, and Ang II. Our findings provided the first evidence that an imbalance in the RAS classical and counter-regulatory arms may play a role in HD pathophysiology.     

The Effects of Probiotics,Prebiotics and Synbiotics in Non-Alcoholic Fat Liver Disease (NAFLD) and Non-Alcoholic Steatohepatitis (NASH): A Systematic Review

Modifications in the microbiota caused by environmental and genetic reasons can unbalance the intestinal homeostasis, deregulating the host’s metabolism and immune system, intensifying the risk factors for the development and aggravation of non-alcoholic fat liver disease (NAFLD). The use of probiotics, prebiotics and synbiotics have been considered a potential and promising strategy to regulate the gut microbiota and produce beneficial effects in patients with liver conditions. For this reason, this review aimed to evaluate the effectiveness of probiotics, prebiotics, and symbiotics in patients with NAFLD and NASH. Pubmed, Embase, and Cochrane databases were consulted, and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines were followed. The clinical trials used in this study demonstrated that gut microbiota interventions could improve a wide range of markers of inflammation, glycemia, insulin resistance, dyslipidemia, obesity, liver injury (decrease of hepatic enzymes and steatosis and fibrosis). Although microbiota modulators do not play a healing role, they can work as an important adjunct therapy in pathological processes involving NAFLD and its spectrums, either by improving the intestinal barrier or by preventing the formation of toxic metabolites for the liver or by acting on the immune system.     

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.     

Targeting the Central Pocket of the Pseudomonas aeruginosa Lectin LecA

Pseudomonas aeruginosa is an opportunistic ESKAPE pathogen that produces two lectins, LecA and LecB, as part of its large arsenal of virulence factors. Both carbohydrate-binding proteins are central to the initial and later persistent infection processes, i. e. bacterial adhesion and biofilm formation. The biofilm matrix is a major resistance determinant and protects the bacteria against external threats such as the host immune system or antibiotic treatment. Therefore, the development of drugs against the P. aeruginosa biofilm is of particular interest to restore efficacy of antimicrobials. Carbohydrate-based inhibitors for LecA and LecB were previously shown to efficiently reduce biofilm formations. Here, we report a new approach for inhibiting LecA with synthetic molecules bridging the established carbohydrate-binding site and a central cavity located between two LecA protomers of the lectin tetramer. Inspired by in silico design, we synthesized various galactosidic LecA inhibitors with aromatic moieties targeting this central pocket. These compounds reached low micromolar affinities, validated in different biophysical assays. Finally, X-ray diffraction analysis revealed the interactions of this compound class with LecA. This new mode of action paves the way to a novel route towards inhibition of P. aeruginosa biofilms.     

Evaluation of traditional semi-hard Brazilian cheeses using chemometric tools to identify possible denomination fraud

This study aimed to evaluate and classify some of the main traditional Brazilian semi-hard cheeses, using multivariate tools to determine possible denomination fraud. Fifty-six samples of Minas Artisanal (MA), Colonial (AC), Minas Padrão (MP) and Meia Cura (MC) cheeses were analysed. All the evaluated parameters indicated high variability. PCA and HCA confirmed two groupings (AC and MP; and MA and MC) with high similarity. The DD-SIMCA method classified the cheeses with 83% accuracy. AC (48%) and MA (20%) cheeses were the most well classified in their respective denomination. These results were efficient in classifying groups and demonstrating the lack of authenticity regarding the denominations of these cheeses.