Small hydropower dam alters the taxonomic composition of benthic macroinvertebrate assemblages in a neotropical river

Hydropower dams substantially modify lotic ecosystems. Most studies regarding their ecological impacts are based on large dams and provide little information about the far more abundant effects of small hydropower dams. Our aim was to characterize the ecological effects of a small hydropower dam and run‐of‐the‐river reservoir on the structure of benthic macroinvertebrate assemblages in the Pandeiros River located in the neotropical savanna of Brazil. We tested the hypothesis that benthic macroinvertebrate assemblages in sites directly affected by the dam and reservoir would show a different taxonomic structure compared with those in free‐flowing sites. We expected to find sensitive native species associated with the free‐flowing sites, whereas resistant and non‐native invasive taxa were expected in impounded sites. We also explored associations between the presence of native and non‐native invasive taxa to each habitat type. We found that the structure of benthic macroinvertebrate assemblages was significantly different between free‐flowing and impounded sites. Also, we found that the dam and reservoir facilitated colonization of non‐native invasive species (Corbicula fluminea and Melanoides tuberculata) because only in those sites they were found in high abundance, in contrast to the free‐flowing sites. Although the environmental conditions imposed by the impoundment altered the structure of benthic macroinvertebrate assemblages, the effects were limited to sites closest to the dam. Our results highlight the necessity of understanding physical habitat changes caused by the presence and management of run‐of‐the‐river dams and reservoirs.     

Analysis of non-coloured phenolics in port wines by capillary zone electrophoresis Influence of grape variety and ageing

 Different experimental varietal port wines were analysed in order to determine differences in the concentrations of phenolic compounds between some commonly used grapes varieties (Touriga Francesa, Touriga Nacional, Tinta Roriz and Tinta Barroca). Although all samples had the same qualitative pattern of non-coloured phenolic compounds, Touriga varieties contained more than twice the concentration of these compounds compared to the Tinta varieties. A preliminary study of the effect of ageing on these compounds revealed an overall increase in those components associated with the bitter or astringent characteristics of food and beverages (tyrosol, gallic acid and catechin). Received: 1 August 1997     

Molybdenum disulphide/titanium low friction coating for gears application

Multi-layer composite surface coatings made of MoS₂/titanium, exhibit good mechanical and tribological properties in several industrial applications. Its applicability to industrial gears is discussed in this work.Several tests, like Rockwell indentations, ball cratering, pin-on-disc and reciprocating wear tests, were performed in order to evaluate the adhesion to the substrate and the tribological performance of this coating.Twin-disc tests, performed at high-contact pressure and high-slide-to-roll ratios, confirmed the good adhesive and tribological properties of the MoS₂/titanium coating and left good indications about the applicability of the MoS₂/titanium coating to gears.Scuffing gear tests were performed in the FZG machine in order to evaluate the anti-scuffing performance of this coating. Finally, the MoS₂/titanium coating was applied to the gearing in a gearbox and its influence on the gearbox efficiency was studied.     

Recycling of solid wastes in the synthesis of Co-bearing calcium hexaluminate pigment

Cobalt doped calcium hexaluminate was firstly synthesized using pure reagents; subsequently, the pure reagents were substituted with industrial wastes, the composition of which had been characterized using X-Ray diffraction and X-Ray fluorescence namely, Al-anodising sludge replaced pure aluminium whilst marble cutting rejects and foundry sand were employed as sources of calcite and silica, respectively. As expected, cobalt doped hibonite was the major phase present in calcined powders and displayed an intense blue coloration due to the incorporation of cobalt in tetrahedral positions, as confirmed by transitions from ⁴A₂(F) to the excited ⁴T₁(F) and ⁴T₁(P) states observed from UV–Vis–NIR absorption spectra. The novel waste-derived hibonite pigment showed strong and stable colouring potential when applied in different ceramic supports.     

Red mud as a substitute coloring agent for the hematite pigment

Red mud (RM), a highly alkaline iron oxide rich sludge obtained during the production of alumina, was treated to work as a coloring agent for ceramic glazes. The approach aims the valorization of this residue, adding environmental and economic value. RM was sintered at different temperatures (1100 °C, 1150 °C, 1200 °C, 1250 °C, 1300 °C and 1350 °C) to assess changes in its mineralogical composition. The obtained powders were characterized by XRD, UV–Vis and CIELab. The samples were added to glazes (transparent, opaque and matte) and their color stability analyzed by CIELab. RM sintered at 1300 °C was compared with commercial hematite producing lower coloring power but yielding better color stability on glazes for temperatures of 1100 °C ± 15 °C, thus presenting RM_1300C as a suitable substitute for the hematite pigment.     

Composition and properties of glass obtained from Early Cretaceous Sidi Aich sands (central Tunisia)

The present work describes the chemical–mineralogical characterization of Barremian sand deposits. These Sidi Aich sands are observed exclusively in central Tunisia; in the Central Atlas two major domains might be discriminated: north–south axis and southern Atlas. In the collected raw samples, quartz and potassic feldspars are depicted with percentages that reach 30 wt.%. The chemical and XRD analyses confirm the existence of K-feldspars. These compounds are known fluxing agents. Since the amount in heavy minerals (<0.36 wt.%) and Fe₂O₃ (<0.71 wt.%) is relatively low, their interest for glass manufacturing is high.In accordance, semi-industrial tests were carried out to produce glass. The obtained bodies were investigated by XRD, attempting to detect the crystalline phases that can appear and influence the technological behaviour of these glasses. Mechanical properties distinguished SMS and SAT glasses when the others are conditioned by microfractures that could be related to annealing stage. The investigation also concerned the colours exhibited by final products (green to amber). This aspect is dependent on the amount of iron and its redox states; ferrous (Fe²⁺)/ferric iron (Fe³⁺) which is here detected in UV–vis–NIR spectra of different tested glasses.     

Safe controllers design for industrial automation systems

The design of safe industrial controllers is one of the most important domains related to Automation Systems research. To support it, synthesis and analysis techniques are available. Among the analysis techniques, two of the most important are Simulation and Formal Verification. In this paper these two techniques are used together in a complementary way. Understanding plant behaviour is essential for obtaining safe industrial systems controllers; hence, plant modelling is crucial to the success of these techniques. A two step approach is presented: first, the use of Simulation and, second, the use of Formal Verification of Industrial Systems Specifications. The specification and plant models used for each technique are described. Simulation and Formal Verification results are presented and discussed. The approach presented in the paper can be applied to real industrial systems, and obtain safe controllers for hybrid plants. The Modelica modelling language and Dymola simulation environment are used for Simulation purposes, and Timed Automata formalism and the UPPAAL real-time model-checker are used for Formal Verification purposes.