Stability of thermal-induced phase transformations in the severely deformed equiatomic Ni–Ti alloys

Nickel–Titanium (Ni–Ti) alloys of two different near-equiatomic chemical compositions (Ni-rich and Ti-rich) are subjected to severe plastic deformation by means of high pressure torsion (HPT) by higher rotation speed and larger total number of rotations. Further, the as-received and severely deformed specimens are subjected to heat treatments at 300 and 350 °C. Phase transformations of the specimens under different conditions are analyzed by employing differential scanning calorimetry and by X-ray diffraction. The results obtained show that in Ti-rich Ni–Ti alloy the sequence of phase transformations is found to be stable against heat treatments and independent of previous HPT process. Also, in Ni-rich Ni–Ti alloy, when it is subjected to HPT, the sequence of phase transformations found to remain unaltered. However, with or without HPT, after the heat treatments at 300 and 350 °C, the sequence of the phase transformation is found to be affected.     

Fermentative hydrogen production with xylose by Clostridium and Klebsiella species in anaerobic batch reactors

Hydrogen production was obtained from low concentrations of xylose metabolized by heat treated inoculum obtained from the slaughterhouse wastewater treatment UASB reactor installed in Brazil. The molecular biological analysis Clostridium and Klebsiella species, recognized as H₂ and volatile acid producers, in addition to Burkholderia species and uncultivated bacteria. The assays were carried out in batch reactors: (1) 630.0 mg xylose/L, (2) 1341.0 mg xylose/L, (3) 1848.0 mg xylose/L and (4) 3588.0 mg xylose/L. The following yields were obtained: 3% (0.2 mol H₂/mol xylose), 8% (0.5 mol H₂/mol xylose), 10% (0.6 mol H₂/mol xylose) and 14% (0.8 mol H₂/mol xylose), respectively. The end products obtained were acetic acid, butyric acid, methanol and ethanol in all of the anaerobic reactors. The concentrations of xylose did not inhibit microbial growth and hydrogen production. This suggested that low concentrations of xylose should be added to wastewater to produce hydrogen.     

Occurrence of filamentous fungi and yeasts in three different drinking water sources

In order to determine the occurrence of fungi in different drinking water sources and capture variability in terms of matrix composition and seasonal effects, surface water, spring water, and groundwater samples were collected in numerous sampling events. The occurrence and significance of fungi detected in the different water sources are reported and discussed in terms of colony-forming units per millilitre and by the identification of the most frequently detected isolates, at the species level, based on morphology and other phenotypic characters. All the samples were also analyzed in terms of total coliforms and Escherichia coli that are widely monitored bacteria considered as microbiology indicators of water quality. All the groundwater samples showed significantly lower levels of total coliforms, E. coli, and fungi compared to the surface and spring water samples. No significant correlations were found between the levels of fungi detected in all the matrices and the physico-chemical parameters and bacteria regularly monitored by drinking water utilities. Fifty-two fungi isolates were identified in this study, most of which have never been described to occur in water sources. The results obtained show that fungi occur widely in drinking water sources and that further studies should be conducted to address their biodegradation potential as well as if the drinking water treatment processes currently used are effective in removing these organisms and the potential secondary metabolites produced.     

Carbide phases formed in WC–M (M = Fe/Ni/Cr) systems

The effect of composition in the formation of carbides in the WC–M (M = Fe/Ni/Cr) system has been studied. Three conventional compositions have been prepared with 10 wt.% of metallic binder. Fe as a metallic binder was first studied and its partial substitution by Ni and Cr was also investigated. A WC powder coated with a similar binder (Fe/Ni/Cr) amount was also investigated. The XRD results, after thermal treatment at 1400 °C, reveal that the substitution of half percent of the iron content by Ni stabilized the austenite Fe(γ) formation. The introduction of Cr in the binder composition induces the formation of Cr₂C carbide. With the decrease of Cr amount in the binder composition of the coated powder, Cr₂C carbide was not formed, but instead other carbide, M₆C, was detected. In order to eliminate this carbide a small excess of carbon (3.6 wt.%) was added to the coated powder. The results are discussed in terms of the phases formed, the binder composition and the final carbon content.     

Alkali free hydrolysis of sodium borohydride for hydrogen generation under pressure

The present study is related with the production of hydrogen gas (H₂), at elevated pressures and with high gravimetric storage density, to supply a PEM fuel cell on-demand. To achieve this goal, solid sodium borohydride (NaBH₄) was mixed with a proper amount of a powder reused nickel–ruthenium based catalyst (Ni–Ru based/NaBH₄: 0.2 and 0.4 g/g; ≈150 times reused) inside the bottom of a batch reactor. Then, a stoichiometric amount of pure liquid water (H₂O/NaBH₄: 2–8 mol/mol) was added and the catalyzed NaBH₄ hydrolysis evolved, in the absence of an alkali inhibitor. In this way, this research work is designated alkali free hydrolysis of NaBH₄ for H₂ generation. This type of hydrolysis is excellent from an environmental point of view because it does not involve strongly caustic solutions. Experiments were performed in three batch reactors with internal volumes 646, 369 and 229 cm³, and having different bottom geometries (flat and conical shapes). The H₂ generated was a function of the added water and completion was achieved with H₂O/NaBH₄ = 8 mol/mol. The results show that hydrogen yields and rates increase remarkably increasing both system temperature and pressure. Reactor bottom shape influences deeply H₂ generation: the conical bottom shape greatly enhances the rate and practically eliminates the reaction induction time. Our system of compressed hydrogen generation up to 1.26 MPa shows 6.3 wt% and 70 kg m⁻³, respectively, for gravimetric and volumetric hydrogen storage capacities (materials-only basis) and therefore is a viable hydrogen storage candidate for portable applications.     

Characterization and Technological Features of Autochthonous Coagulase‐Negative Staphylococci as Potential Starters for Portuguese Dry Fermented Sausages

The manufacture of dry fermented sausages is an important part of the meat industry in Southern European countries. These products are usually produced in small shops from a mixture of pork, fat, salt, and condiments and are stuffed into natural casings. Meat sausages are slowly cured through spontaneous fermentation by autochthonous microbiota present in the raw materials or introduced during manufacturing. The aim of this work was to evaluate the technological and safety features of coagulase‐negative staphylococci (CNS) isolated from Portuguese dry fermented meat sausages in order to select autochthonous starters. Isolates (n = 104) obtained from 2 small manufacturers were identified as Staphylococcus xylosus, Staphylococcus equorum, Staphylococcus saprophyticus, and Staphylococcus carnosus. Genomically diverse isolates (n = 82) were selected for further analysis to determine the ability to produce enzymes (for example, nitrate‐reductases, proteases, lipases) and antibiotic susceptibility. Autochthonous CNS producing a wide range of enzymes and showing low antibioresistance were selected as potential starters for future use in the production of dry fermented meat sausages.     

Thermal-morphological characterisation of starch from peach-palm (Bactris Gasipaes kunth) fruit (Pejibaye)

The objective of this study was to characterize the starch of the peach-palm fruit. The starch was subjected to thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, x-ray diffraction, and scanning electron microscopy. The thermogravimetric analysis showed 76.62% of the weight loss in the temperature range from 251.7 to 380.6 ºC. The peak in differential scanning calorimetry was obtained at 70.0 ^ºC. Fourier transform infrared spectroscopy were obtained with a wavelength band of 528 to 3421 cm^?1. The x-ray diffraction corresponded to C-type crystals. The granule sizes ranged from 1.60 to 8.48 μm.     

Advances on the molecular characterization,clinical relevance,and detection methods of Gadiform parvalbumin allergens

Gadiform order includes several fish families, from which Gadidae and Merlucciidae are part of, comprising the most commercially important and highly appreciated fish species, such as cod, pollock, haddock, and hake. Parvalbumins, classified as calcium-binding proteins, are considered the main components involved in the majority of fish allergies. Nine and thirteen parvalbumins were identified in different fish species from Gadidae and Merlucciidae families, respectively. This review intends to describe their molecular characterization and the clinical relevance, as well as the prevalence of fish allergy. In addition, the main protein- and DNA-based methods to detect fish allergens are fully reviewed owing to their importance in the safeguard of sensitized/allergic individuals.