Growth and characterization of the oxide scales and core/shell nanowires on Ti-6Al-4 V particles during thermal oxidation

Nanowires were grown on as-received and milled particles of Ti-6Al-4 V (Ti64) alloy under an optimum condition of 750 degrees C in an Ar atmosphere containing 15 ppm of oxygen. The as-grown nanowires and the underneath oxide scales developed on Ti64 particles were characterized by X-ray diffiactometry (XRD), field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) equipped with energy dispersive X-ray spectroscope (EDS). Results revealed the formation of oxide scales consisting of double layers on the surface of Ti64 particles. The outer oxide scale was a mixture of Al2O3 and TiO2 whereas the inner oxide scale was solely TiO2. An unoxidized core was present inside depending On the size of the Ti64 particles at the initial state. The thickness of the outer oxide scale was also dependent on the size of the Ti64 particles. The nanowires grew in the outward direction from the outer oxide scale during thermal oxidation. The as-grown nanowires had fine and thick dimensions. Both types of nanowires had a core-shell structure where the core was made of TiO2 and the shell was Al2O3. It was seen that both residual and induced stress played a role for the growth of nanowires on Ti64 particles during thermal oxidation. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Variation in the genomic locations and sequence conservation of STAR elements among staphylococcal species provides insight into DNA repeat evolution.

Background:Staphylococcus aureus Repeat (STAR) elements are a type of interspersed intergenic direct repeat. In this study the conservation and variation in these elements was explored by bioinformatic analyses of published staphylococcal genome sequences and through sequencing of specific STAR element loci from a large set of S. aureus isolates. Results:Using bioinformatic analyses, we found that the STAR elements were located in different genomic loci within each staphylococcal species. There was no correlation between the number of STAR elements in each genome and the evolutionary relatedness of staphylococcal species, however higher levels of repeats were observed in both S. aureus and S. lugdunensis compared to other staphylococcal species. Unexpectedly, sequencing of the internal spacer sequences of individual repeat elements from multiple isolates showed conservation at the sequence level within deep evolutionary lineages of S. aureus. Whilst individual STAR element loci were demonstrated to expand and contract, the sequences associated with each locus were stable and distinct from one another. Conclusions:The high degree of lineage and locus-specific conservation of these intergenic repeat regions suggests that STAR elements are maintained due to selective or molecular forces with some of these elements having an important role in cell physiology. The high prevalence in two of the more virulent staphylococcal species is indicative of a potential role for STAR elements in pathogenesis

Ocorrência, aspectos toxicológicos, métodos analíticos e controle da patulina em alimentos Occurrence, toxicological aspects, analytical methods and control of patulin in food

A patulina é uma micotoxina produzida por várias espécies de Penicillium, Aspergillus e Byssochlamys. Em experimentos com animais, ela demonstrou ter atividade mutagênica, carcinogênica e teratogênica. Tem sido freqüentemente encontrada em maçãs e derivados. A patulina é facilmente transferida da maçã para o suco durante o processamento devido a sua alta solubilidade em água. Essa micotoxina é muito estável ao aquecimento em meio ácido, como no suco de maçã. Assim, a presença de patulina em suco de maçã é um indicador da qualidade das maçãs utilizadas no processamento. Muitos métodos têm sido desenvolvidos para a determinação da patulina, principalmente baseados na extração líquido-líquido com acetato de etila e determinação por CLAE. É importante evidenciar a necessidade de legislação que regulamente limites dessa micotoxina em alimentos no Brasil. Esta revisão bibliográfica tem como objetivos descrever as principais características da patulina, a ocorrência, os aspectos toxicológicose os métodos desenvolvidos para sua detecção e controle durante os estágios da produção da maçã e suco.<br>Patulin is a mycotoxin produced by several Penicillium, Aspergillus and Byssochlamys species. Patulin is a highly toxic compound which has shown to be mutagenic, carcinogenic and teratogenic in experiments with animals. It has often been found in apples and apple products. Patulin is easily transfered into apple juice during processing due to its high solubility in water. This mycotoxin is very stable to heat in acidic medium as in apple juice. Thus, patulin content of apple juice is an indicator of the quality of the apples used to juice production. Many methods have been developed for the patulin determination mainly based on liquid-liquid extraction with ethyl acetate and use of HPLC for detection. It is important to show the need of legislation that imposes patulin limits in foods in Brazil. The objectives of this review are to describe the main patulin characteristics, occurrence, toxicological aspects, methods developed for patulin detection and control during the stages of apple and juice production