Peptide biomarkers as a way to determine meat authenticity

Meat fraud implies many illegal procedures affecting the composition of meat and meat products, something that is commonly done with the aim to increase profit. These practices need to be controlled by legal authorities by means of robust, accurate and sensitive methodologies capable to assure that fraudulent or accidental mislabelling does not arise. Common strategies traditionally used to assess meat authenticity have been based on methods such as chemometric analysis of a large set of data analysis, immunoassays or DNA analysis. The identification of peptide biomarkers specific of a particular meat species, tissue or ingredient by proteomic technologies constitutes an interesting and promising alternative to existing methodologies due to its high discriminating power, robustness and sensitivity. The possibility to develop standardized protein extraction protocols, together with the considerably higher resistance of peptide sequences to food processing as compared to DNA sequences, would overcome some of the limitations currently existing for quantitative determinations of highly processed food samples. The use of routine mass spectrometry equipment would make the technology suitable for control laboratories.     

Synergistic inhibitory effect of citral with selected phenolics against Zygosaccharomyces bailii

Antifungal susceptibilities of Zygosaccharomyces bailii to individual and binary mixtures of citral with selected phenolics were evaluated to identify synergistic combinations. Individual effects of citral, vanillin, thymol, carvacrol, and eugenol concentrations and combined effects of citral with the other phenolic compounds on the growth of Z. bailii were evaluated in potato dextrose agar, adjusted with sucrose to a water activity of 0.99 or 0.95, and hydrochloric acid to pH 4.5 or 3.5. MICs for individual and binary antimicrobial mixtures were identified and then transformed to fractional inhibitory concentrations. Inhibitory concentrations of citral and vanillin were higher than 650 ppm, whereas for thymol, eugenol, and carvacrol, concentrations were lower than 250 ppm for several of the studied water activity-pH conditions. Combining citral with the other phenolic compounds, fractional inhibitory concentration (FIC) and FIC(Index) varied from 0.216 to 0.582. FIC(Index) demonstrated synergistic effects on Z. bailii inhibition when citral was used in combination with vanillin, thymol, carvacrol, or eugenol. Therefore, the relative amount of antimicrobials could be greatly reduced.     

Characterization of surface‐modified polyalkanoate films for biomedical applications

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBHV) films prepared by solvent casting were treated with oxygen, argon, and nitrogen radiofrequency‐generated plasmas. The analysis by attenuated total reflectance infrared spectroscopy and X‐ray absorption near edge spectroscopy of modified surfaces showed an increase of hydroxyl and unsaturated groups, compared with unmodified surfaces. Water contact angles decreased after a short time of exposure (<30 s) for all types of plasma. At long exposure times (>30 s), the water contact angles appeared to be independent of treatment time for nitrogen and argon plasmas, whereas they continuously decreased for films treated with oxygen. HaCaT cultures on nontreated and treated PHBHV films showed that short plasma exposures of 10–20 s improve cell attachment to a greater extent than long exposure times habitually used in polymer surface plasma treatment. The film surface topology did not influence cell attachment. These results illustrate the importance of a detailed characterization of the surface physicochemistry in plasma‐modified substrates designed as part of a strategy to optimize specific cell–biomaterial interactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Base case process development for energy efficiency improvement, application to a Kraft pulping mill. Part I: Definition and characterization

The development of a base-case process is a fundamental step in an energy efficiency study to obtain reliable results. However, this step is often overlooked and there are no clear guidelines for the systematic development of the base-case. A methodology has been proposed to properly define and evaluate the complete process for a subsequent in-depth energy analysis. It consists of two stages: definition and characterization of the process, and benchmarking analysis. In this paper, the first stage is presented. The base-case should encompass the process and the utilities systems, i.e., steam and water, as they are the driving forces of the chemical transformations. A four-pronged procedure is proposed to properly define and characterize a process and its utilities: data gathering, master diagram construction, utilities systems analysis, and simulation. The main objective is to build a computer simulation model to provide detailed information on production, distribution, utilization and post-utilization treatment of steam and water. Process inefficiencies are also identified, such as the low condensate recovery or the presence of non-isothermal mixing points. The procedure has been applied to an operating Kraft pulping mill in Eastern Canada.     

Insulin-Dependent H2O2 Production Is Higher in Muscle Fibers of Mice Fed with a High-Fat Diet

Insulin resistance is defined as a reduced ability of insulin to stimulate glucose utilization. C57BL/6 mice fed with a high-fat diet (HFD) are a model of insulin resistance. In skeletal muscle, hydrogen peroxide (H₂O₂) produced by NADPH oxidase 2 (NOX2) is involved in signaling pathways triggered by insulin. We evaluated oxidative status in skeletal muscle fibers from insulin-resistant and control mice by determining H₂O₂ generation (HyPer probe), reduced-to-oxidized glutathione ratio and NOX2 expression. After eight weeks of HFD, insulin-dependent glucose uptake was impaired in skeletal muscle fibers when compared with control muscle fibers. Insulin-resistant mice showed increased insulin-stimulated H₂O₂ release and decreased reduced-to-oxidized glutathione ratio (GSH/GSSG). In addition, p47^phox and gp91^phox (NOX2 subunits) mRNA levels were also high (~3-fold in HFD mice compared to controls), while protein levels were 6.8- and 1.6-fold higher, respectively. Using apocynin (NOX2 inhibitor) during the HFD feeding period, the oxidative intracellular environment was diminished and skeletal muscle insulin-dependent glucose uptake restored. Our results indicate that insulin-resistant mice have increased H₂O₂ release upon insulin stimulation when compared with control animals, which appears to be mediated by an increase in NOX2 expression.     

Evaluation of the potential hydrogen production by diazotrophic Burkholderia species

Hydrogen (H₂) is considered one of the most promising fuels for sustainable energy. Because nitrogenase produces H₂ as a normal by-product, we tested the N₂-fixing bacterial strains Burkholderia unamae and Burkholderia tropica to determine their H₂ production capacities. To maximize H₂ production, several culture conditions were tested and optimized, including atmospheric conditions, carbon sources and chemical compounds such as enzyme cofactors and sugar cane molasses. The results showed that both strains were capable of H₂ production. The culture medium with the highest H₂ yield was composed of 1% v/v molasses enriched with Na₂MoO₄ (0.2 g/L), FeSO₄ (0.2 g/L) and cysteine (0.02 g/L) under a partial vacuum (air 20% v/v) without Ar final atmosphere. Under these conditions, the highest H₂ production rate obtained was 24.64 mmol H₂/L for B. unamae. The present study contributes an optimization process for H₂ production in N₂-fixing Burkholderia species. We propose further research and development to improve H₂ production rates in order to make biohydrogen a tangible reality.     

Optical flow estimation in cardiac CT images using the steered Hermite transform

This paper describes a new method to estimate the heart's motion in computer tomography images with the inclusion of a bio-inspired image representation model. Our proposal is based on the polynomial decomposition of each of the images using the steered Hermite transform as a representation of the local characteristics of images from an perceptual approach within a multiresolution scheme.The Hermite transform is a model that incorporates some of the more important properties of the first stages of the human visual system, such as the overlapping Gaussian receptive fields, the Gaussian derivative model of early vision and the multiresolution analysis.We propose an approach for optical flow estimation that incorporates image structure information extracted from the steered Hermite coefficients, that is later used as local motion constraints in a differential estimation method that involves several of the constraints seen in the current differential methods, which allows obtaining accurate flows.Considering the importance of understanding the movement of certain structures such as left ventricular and myocardial wall for better medical diagnosis, our main goal is to find an estimation method useful to assist diagnosis tasks in computer tomography images.     

Uniform boundary controllability of a discrete 1-D wave equation

A numerical scheme for the controlled discrete 1-D wave equation is considered. We prove the convergence of the boundary controls of the discrete equations to a control of the continuous wave equation when the mesh size tends to zero when time and space steps coincide. This positive result is in contrast with previous negative ones for space semi-discretizations.     

Microstructure and Strengthening Mechanisms in an Ultrafine Grained Al-Mg-Sc Alloy Produced by Powder Metallurgy

Additions of Sc to an Al-Mg matrix were investigated, paying particular attention to the influence of Al₃Sc precipitates and other dispersoids, as well as grain size, on mechanical behavior. Prior studies have shown that Sc significantly increases the strength of coarse-grained Al-Mg alloys. Prompted by these findings, we hypothesized that it would be of fundamental and technological interest to study the behavior of Sc additions to an ultrafine-grained (UFG) microstructure (e.g., 100’s nm). Accordingly, we investigated the microstructural evolution and mechanical behavior of a cryomilled ultrafine grained Al-5Mg-0.4Sc (wt pct) and compared the results to those of an equivalent fine-grained material (FG) produced by powder metallurgy. Experimental materials were consolidated by hot isostatic pressing (HIP’ing) followed by extrusion or dual mode dynamic forging. Under identical processing conditions, UFG materials generate large Al₃Sc precipitates with an average diameter of 154 nm and spaced approximately 1 to 3 μm apart, while precipitates in the FG materials have a diameter of 24 nm and are spaced 50 to 200 nm apart. The strengthening mechanisms are calculated for all materials and it is determined that the greatest strengthening contributions for the UFG and FG materials are Mg-O/N dispersion strengthening and precipitate strengthening, respectively.     

Stress-Induced Grain Growth in an Ultra-Fine Grained Al Alloy

This paper reports on a study of the stress-induced grain growth phenomenon in the presence of second-phase particles and solutes segregated at grain boundaries (GBs) during high-temperature deformation of an ultra-fine grained (UFG) Al alloy synthesized via the consolidation of mechanically milled powders. Our results show that grain growth was essentially inhibited during annealing at 673 K (400 °C) in the absence of an externally applied stress, whereas in contrast, grain growth was enhanced by a factor of approximately 2.7 during extrusion at 673 K (400 °C). These results suggest that significant grain growth during hot extrusion was attributable to the externally applied stresses stemming from the state of stress imposed during extrusion and that the externally applied stresses can overcome the resistance forces generated by second-phase particles and solutes segregated at GBs. The mechanisms underlying stress-induced grain growth were identified as GB migration and grain rotation, which were accompanied by dynamic recovery and possible geometric dynamic recrystallization, while discontinuous dynamic recrystallization did not appear to be operative.