Application of hazard analysis critical control points system for the control of aflatoxins in the Brazilian groundnut‐based food industry

This study was conducted to identify and assess the critical control points (CCPs) in groundnut‐based food production in southern Brazil in order to reduce or eliminate aflatoxin contamination. This methodology has been suggested by the Food and Agriculture Organization (FAO) of the United Nations. Reception of prime matter, groundnut storage, roasting and thermal treatment were the main CCPs identified. Critical factors were the determination of aflatoxin, moisture content and water activity (A_w) during groundnut reception and storage, control of temperature, roasting time and thermal treatment in the groundnut‐based food manufacturing. The critical limit for moisture was 8.2% and 0.6 was established for A_w. In Brazil, the limit for aflatoxins B₁, B₂, G₁ and G₂ has been established at 20 ppb. Temperatures of 180 °C/1 h and 80 °C/40 min were established for roasting and thermal treatment stages of groundnut‐based food, respectively.     

Circulating 16S RNA in Biofluids: Extracellular Vesicles as Mirrors of Human Microbiome?

The human body is inhabited by around 10¹³ microbes composing a multicomplex system, termed microbiota, which is strongly involved in the regulation and maintenance of homeostasis. Perturbations in microbiota composition can lead to dysbiosis, which has been associated with several human pathologies. The gold-standard method to explore microbial composition is next-generation sequencing, which involves the analysis of 16S rRNA, an indicator of the presence of specific microorganisms and the principal tool used in bacterial taxonomic classification. Indeed, the development of 16S RNA sequencing allows us to explore microbial composition in several environments and human body districts and fluids, since it has been detected in “germ-free” environments such as blood, plasma, and urine of diseased and healthy subjects. Recently, prokaryotes showed to generate extracellular vesicles, which are known to be responsible for shuttling different intracellular components such as proteins and nucleic acids (including 16S molecules) by protecting their cargo from degradation. These vesicles can be found in several human biofluids and can be exploited as tools for bacterial detection and identification. In this review, we examine the complex link between circulating 16S RNA molecules and bacteria-derived vesicles.     

Inactivation of Pseudomonas aeruginosa in mineral water by DP1 bacteriophage immobilized on ethylene-vinyl acetate copolymer used as seal caps of plastic bottles

Pseudomonas aeruginosa has been found in bottled natural mineral water, even though its presence is not allowed in this product by different food regulations. This study aimed to investigate the inactivation of P. aeruginosa present in mineral water by vB_PaeM_CEB_DP1 (short name DP1) bacteriophage immobilized on ethylene-vinyl acetate (EVA) copolymer used as seal caps of plastic bottles. EVA was chemically modified using microwave-assisted alcoholysis, improving polymer-phage binding. After that, DP1 phage was attached to EVA and EVA-OH copolymers and both surfaces were tested for plaque formation using P. aeruginosa. Then, both materials containing immobilized phages were used as seal caps of plastic bottles and its antimicrobial capacity was tested against P. aeruginosa contaminating mineral water. The EVA-OH resulted in higher hydrogen bond density that contributed significantly to the phage immobilization on the polymer surface. The polymers containing immobilized phages were able to reduce 0.53 log of P. aeruginosa population present inside mineral water bottles after 14 days.     

Physical Layer Cryptography and Cognitive Networks

Recently the huge development of different and heterogeneous wireless communication systems raises the problem of growing spectrum scarcity. Cognitive radio tends to solve this problem by dynamically utilizing the spectrum. Security in cognitive radio network becomes a challenging issue, since more chances are given to attackers by cognitive radio technology compared to conventional wireless network. These weaknesses are introduced by the nature itself of cognitive radio, and they may cause serious impact to the network quality of service. However, to the authors’ knowledge, there are no specific secure protocols for cognitive radio networks. This paper will discuss the vulnerabilities inherent to cognitive radio systems, identify novel types of abuse, classify attacks, and analyze their impact. Security solutions to mitigate such threats will be proposed and discussed. In particular, physical payer security will be taken into account. A new modulation technique, able to encrypt the radio signal without any a priori common secret between the two nodes, was previously proposed by the authors (Mucchi et al. 2009, WPC 51, 67–80; Mucchi et al. 2010, WPC 53, 329–347). The information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. A loop scheme is designed for unique recovering of mutual information. This contribution improves the previous works by proposing the noise loop modulation as physical layer security technique for cognitive radio networks.     

Mizellare Extraktion von Zink mit Di(2‐ethylhexyl)phosphorsäure in Gegenwart des Tensids Cetyltrimethylammoniumbromid

Addition of surfactants can influence extraction processes. In the case were the surfactant concentration is above the critical micelles concentration the mass transfer rate increases by the formation of inverse micelles and therefore the micellar extraction mechanism of zinc. The influence of the added surfactant cetyltrimethylammonium bromide (CTAB) on zinc extraction with the cation exchanger di(2‐ethylhexyl)phosphoric acid (D₂EHPA) is analysed based on extraction equilibriums and mass transfer experiments. The observed experimental results are explained phenomenologically.     

Mechanical Exfoliation of Select MAX Phases and Mo4Ce4Al7C3 Single Crystals to Produce MAXenes

MXenes—2D carbides/nitrides derived from their bulk nanolamellar M_n+1AX_n phase (MAX) counterparts—are, for the most part, obtained by chemical etching. Despite the fact that the M? A bonds in the MAX phases are not weak, in this work it is demonstrated that relatively large MAX single crystals can be mechanically exfoliated using the adhesive tape method to produce flakes whose thickness can be reduced down to half a unit cell. The exfoliated flakes, transferred onto SiO₂/Si substrates, are analyzed using electric force microscopy (EFM). No appreciable variation in EFM signal with flake thickness is found. EFM contrast between the flakes and SiO₂ not only depends on the contact surface potential, but also on the local capacitance. The contribution of the latter can be used to show the metallic character—confirmed by four‐contact resistivity measurements—of even the thinnest of flakes. Because the A‐layers are preserved, strictly speaking MXenes are not dealt with in this work, but rather MAXenes. This is important in the case where the “A” layers contain magnetic elements such as Mo₄Ce₄Al₇C₃, whose structure is a derivative of the MAX structure.     

Heat Shock Proteins Revisited: Using a Mutasynthetically Generated Reblastatin Library to Compare the Inhibition of Human and Leishmania Hsp90s

Thirteen new reblastatin derivatives, with alkynyl, amino and fluoro substituents on the aromatic ring, were prepared by a chemo‐biosynthetic approach using an AHBA(?) mutant strain of Streptomyces hygroscopicus, the geldanamycin producer. The inhibitory potencies of these mutaproducts and of an extended library of natural products and derivatives were probed with purified heat shock proteins (Hsps), obtained from Leishmania braziliensis (LbHsp90) as well as from human sources (HsHsp90). We determined the activities of potential inhibitors by means of a displacement assay in which fluorescence‐labelled ATP competes for the ATP binding sites of Hsps in the presence of the inhibitor in question. The results were compared with those of cell‐based assays and, in selected cases, of isothermal titration calorimetry (ITC) measurements. In essence, reblastatin derivatives are also able to bind effectively to the ATP‐binding site of LbHsp90, and for selected derivatives, moderate differences in binding to LbHsp90 and HsHsp90 were encountered. This work demonstrates that parasitic heat shock proteins can be developed as potential pharmaceutical targets.