Corrosion mechanisms in ADI parts

The objective of this research is to study the influence of microstructure and grinding on the corrosion resistance of ADI in salt water. Immersion and electrochemical tests were performed on samples austempered at two different temperatures and ground. The results indicate that the dissolution rate increases as the nodule count does, and it is also affected by the microstructure and by the surface changes introduced during grinding. A porous layer is formed on ADI-corroded surface due to the selective dissolution of ferrite, and a preferential dissolution of the matrix around graphite is noticeable. Ground surfaces are less corrosion resistant than polished ones.     

Hyperspectral imaging of nanoparticles in biological samples: Simultaneous visualization and elemental identification

While engineered nanomaterials (ENMs) are increasingly incorporated into industrial processes and consumer products, the potential biological effects and health outcomes of exposure remain unknown. Novel advanced direct visualization techniques that require less time, cost, and resource investment than electron microscopy (EM) are needed for identifying and locating ENMs in biological samples. Hyperspectral imaging (HSI) combines spectrophotometry and imaging, using advanced optics and algorithms to capture a spectrum from 400 to 1000 nm at each pixel in an enhanced dark‐field microscopic (EDFM) image. HSI‐EDFM can be used to confirm the identity of the materials of interest in a sample and generate an image “mapping” their presence and location in a sample. Hyperspectral mapping is particularly important for biological samples, where ENM morphology is visually indistinct from surrounding tissue structures. While use of HSI (without mapping) is increasing, no studies to date have compared results from hyperspectral mapping with conventional methods. Thus, the objective of this study was to utilize EDFM‐HSI to locate, identify, and map metal oxide ENMs in ex vivo histological porcine skin tissues, a toxicological model of cutaneous exposure, and compare findings with those of Raman spectroscopy (RS), energy‐dispersive X‐ray spectroscopy (EDS), and scanning electron microscopy (SEM). Results demonstrate that EDFM‐HSI mapping is capable of locating and identifying ENMs in tissue, as confirmed by conventional methods. This study serves as initial confirmation of EDFM‐HSI mapping as a novel and higher throughput technique for ENM identification in biological samples, and serves as the basis for further protocol development utilizing EDFM‐HSI for semiquantitation of ENMs. Microsc. Res. Tech. 79:349–358, 2016. © 2016 Wiley Periodicals, Inc.     

THE EFFECT OF THICKENER ON THE RHEOLOGY OF COATING COLORS

The effect of type and amount of thickener on the shear and extensional rheological properties of paper coating colors was studied. A coarse delaminated kaolin clay was used as pigment and either a carboxy methylcellulose (CMC) or an associative gum was used as thickener. The shear properties were evaluated with a stress controlled rheometer and the extensional properties were obtained at high strain rates using an orifice flow meter. The apparent extensional viscosity was compared to the shear viscosity in terms of the Trouton ratio, which was shown to exceed considerably the theoretical value of 3 expected for Newtonian fluids. Suspensions formulated with the associative gum exhibited more pronounced strain hardening at high strain rates than those prepared with CMC.     

Field sludge characterization obtained from inner of pipelines

Physicochemical characterization of sludge obtained from refined hydrocarbons transmission pipeline was carried out through Mössbauer spectroscopy and X-ray diffraction. The Mössbauer and X-ray patterns indicate the presence of corrosion products composed of different iron oxide and sulfide phases. Hematite (α-Fe₂O₃), magnetite (Fe₃O₄), maghemite (γ-Fe₂O₃), magnetic and superparamagnetic goethite (α-FeOOH), pyrrhotite (Fe_1−xS), akaganeite (β-FeOOH), and lepidocrocite (γ-FeOOH) were identified as corrosion products in samples obtained from pipeline transporting Magna and Premium gasoline. For diesel transmission pipeline, hematite, magnetite, and magnetic goethite were identified. Corrosion products follow a simple reaction mechanism of steel dissolution in aerated aqueous media at a near-neutral pH. Chemical composition of the corrosion products depends on H₂O and sulfur inherent in fluids (traces). These results can be useful for decision-making with regard to pipeline corrosion control.     

Morphological determinants of bite force capacity in insects: a biomechanical analysis of polymorphic leaf-cutter ants

The extraordinary success of social insects is partially based on division of labour, i.e. individuals exclusively or preferentially perform specific tasks. Task preference may correlate with morphological adaptations so implying task specialization, but the extent of such specialization can be difficult to determine. Here, we demonstrate how the physical foundation of some tasks can be leveraged to quantitatively link morphology and performance. We study the allometry of bite force capacity in Atta vollenweideri leaf-cutter ants, polymorphic insects in which the mechanical processing of plant material is a key aspect of the behavioural portfolio. Through a morphometric analysis of tomographic scans, we show that the bite force capacity of the heaviest colony workers is twice as large as predicted by isometry. This disproportionate ‘boost’ is predominantly achieved through increased investment in muscle volume; geometrical parameters such as mechanical advantage, fibre length or pennation angle are likely constrained by the need to maintain a constant mandibular opening range. We analyse this preference for an increase in size-specific muscle volume and the adaptations in internal and external head anatomy required to accommodate it with simple geometric and physical models, so providing a quantitative understanding of the functional anatomy of the musculoskeletal bite apparatus in insects.     

The protective ability of Mediterranean dietary plants against the oxidative damage: The role of radical oxygen species in inflammation and the polyphenol,flavonoid and sterol contents

Ten hydroalcoholic extracts of edible plants from the Calabria region (Italy) were evaluated for their in vitro antioxidant and antiradical properties and in vivo topical anti-inflammatory activity. All the extracts had radical-scavenging and/or antioxidant properties, the most active plants being hawkweed oxtongue and viper’s bugloss. The best free radical (DPPH·)-scavenging activity was found in hawkweed oxtongue and chicory leaves extracts (IC₅₀ = 25 and 26 μg/ml, respectively). Hawkweed oxtongue, poppy and viper’s bugloss extracts showed the greatest inhibition of linoleic acid oxidation (IC₅₀ = 3 μg/ml). Viper’s bugloss and hawkweed oxtongue extracts had the greatest antioxidant effect on bovine brain peroxidation (IC₅₀ = 11 and 22 μg/ml). All the extracts also showed an anti-inflammatory effect: 300 μg/cm² provoked oedema reductions ranging from 18% to 43%. Cress was the most active plant. Chicory leaves contained the highest amount of phenolics (190 mg/g) whilst Rush crimps contained the highest amount of flavonoids (32.9 mg/g), followed by hawkweed oxtongue (15.8 mg/g). Cress contained the highest number of sterols. Among them, γ-sitosterol (12.2%) and ergost-5-en-3-ol (3β) (4.5%) were found to be the major constituents. Moreover, three of the identified molecules (stigmasta-5,23-dien-3β-ol, stigmasta-5,24(28)-dien-3-ol (3β,22E) and 9,19-cyclolanost-24-en-3-ol (3β)) were found in this plant only.     

Impact of damming the Mogi-Guaçu River (São Paulo State, Brazil) on reservoir limnological variables

This study examined the effects of the damming of the Mogi‐Guaçu River (São Paulo State, Brazil) on the surface current velocity, water temperature, Secchi disc transparency, turbidity, colour, conductivity, pH and concentrations of nutrients and pigments. Surface‐water samples were taken before, during and after the reservoir was filled. Three sampling sites were established, one in the upper reach of the reservoir, one in the central area of the reservoir and one downstream from the dam. An additional sampling site was established on the Peixe River, the major tributary of the Mogi‐Guaçu in the study area. After filling of the reservoir, the surface current velocity tended to decrease, excepting downstream of the dam. The pH, and the Kjeldahl nitrogen, ammonia and chlorophyll‐a concentrations, tended to increase. The nitrite concentrations increased mainly in the upper reach and central area of the reservoir. The Secchi disc transparency and colour tended to decrease. A decreasing trend in dissolved oxygen concentration was observed mainly at the central area of reservoir. The conductivity tended to decrease, later returning to levels observed prior to reservoir filling. The nitrate, total phosphorus and orthophosphate concentrations exhibited an increasing trend after reservoir filling, followed by a decreasing concentration, reaching lower levels than those found prior to reservoir filling. High phaeophytin concentrations were measured for the filling phase. The observed water quality changes for Mogi‐Guaçu Reservoir generally were not as extreme as those observed for other tropical reservoirs. This trend was related to the operation of the reservoir. As Mogi‐Guaçu Reservoir is a run‐of‐the‐river reservoir with a short water retention time, the flooded area is not extensive and the retention of material and sedimentation upstream from the dam is not remarkable. These facts explain the small water quality changes observed for most of the variables after reservoir filling. The water quality decreased at the in‐lake site in the central part of the reservoir, attaining a hypereutrophic condition. This fact was related to the ageing of the reservoir and to cultural eutrophication.