Behaviour of shot peening combined with WC-Co HVOF coating under complex fretting wear and fretting fatigue loading conditions

This study investigated the fretting and fretting fatigue performance of tungsten carbide–cobalt (WC–Co) HVOF spray coating systems. Fretting wear and fretting fatigue tests of specimens with shot peening and WC–Co coatings on 30NiCrMo substrates were conducted. The WC-Co coating presents very good wear resistance and decreases by more than 9 times the energy wear coefficient (α) under fretting conditions. The tested coating reduces crack nucleation under both fretting and fretting fatigue studied situations. Finally the crack arrest conditions are evaluated by the combined fretting and fretting fatigue investigation. It is shown and explained how and why this combined surface treatment (shot peening and WC–Co) presents a very good compromise against wear and cracking fretting damage

Geomorphological control of fine sedimentation on the northern Portuguese shelf

Six cores sampled at two mud fields located on the northern Portuguese continental shelf have been studied in order to evaluate the control processes of fine sedimentation. The southern mud patch, offshore from the Douro River, is limited on the western side by some Cretaceous and Paleocene outcrops that constitute reliefs of 5-30 m in width; on the contrary, the northern mud patch, offshore from the Minho River, extends along a flat region. Granulometric distribution shows that the sediments from the Minho mud patch are coarser than those from the Douro mud patch, where the grain size diminishes towards the west. Carbonate content is also higher in the Minho mud field. The sediment organisation in fining-up sequences in the Minho mud patch and in the eastern part of the Douro mud patch indicates sediment remobilisation by storms. The Douro mud patch has higher sedimentation rates than the Minho mud patch. The highest values are probably related to the existence of reliefs, which may offer hydrodynamic protection or function as a fine sediment barrier. The elemental distribution for chemical elements was determined in different fractions of these cores. Geochemical patterns are generally quite similar for both mud fields, indicating a common continental origin for the sediments. The major differences in the chemical composition are mainly controlled by the grain-size distribution, either reflecting the presence of coarse quartz particles or a local enrichment in biogenic material.En este trabajo se han estudiado seis testigos de la zona norte de la plataforma continental portuguesa con el objetivo de evaluar los procesos que controlan la sedimentación de materiales finos en esta región. Los fangos acumulados más al sur, frente a la desembocadura del río Duero, están limitados al oeste por relieves cretácicos y paleocenos de 5 a 30 m de altura. Los fangos septentrionales, frente a la desembocadura del río Miño, se extienden sobre una región plana. La distribución granulométrica muestra que estos últimos son más gruesos que los depositados frente al Duero, en los que el tamaño de grano disminuye hacia el oeste. El contenido en carbonato es más elevado en la zona del Miño. Las secuencias granodecrecientes encontradas en los fangos del Miño y en los del sector oriental del Duero indican retrabajamiento del sedimento por tormentas. La tasa de sedimentación es mayor en los fangos situados frente al Duero, donde los valores más altos están relacionados probablemente con la existencia de relieves, los cuales ofrecerían una protección hidrodinámica o actuarían como una barrera para los sedimentos. La distribución de la concentración de diversos elementos químicos a lo largo de los testigos fue determinada para diferentes fracciones. El patrón geoquímico es bastante similar en ambas zonas y pone de manifiesto una procedencia continental de los sedimentos. Las principales diferencias en la composición química están fundamentalmente controladas por la distribución granulométrica, bien por la presencia de granos gruesos de cuarzo, bien por un enriquecimiento local en material biogénico.Instituto Español de Oceanografí

Áreas Potenciais à Formação De Corredores Ecológicos Entre Remanescentes De Mata Atlântica

In Brazil, the remaining areas of Atlantic Forest are intensely fragmented. The connection of forest fragments through ecological corridors is an important step in biodiversity conservation. Certain areas are more resilient, and in those areas, natural forest regeneration, for example, can be encouraged. The aim of this study was to identify areas of greater resilience in order to support the connection of Atlantic Forest fragments with ecological corridors. Forest fragments in the municipality of Paraíba do Sul, in the state of Rio de Janeiro, were mapped using the supervised maximum likelihood classification of an Operational Land Imager (OLI)/Landsat-8 sensor image. Next, we analyzed the influence of terrain attributes (aspect, incident solar radiation, slope, and curvature profile) on natural regeneration. The areas with the greatest potential to achieve natural regeneration and to form ecological corridors were indicated through fuzzy membership functions. Within Paraíba do Sul, 31% of the territory is covered by vegetation in different stages of regeneration. Recordings were made of 1,251 forest fragments in a middle or advanced stage of regeneration. These fragments are usually situated in the southeast, south, and southwest aspects, in areas that receive the least amount of global solar radiation (Wh·m-2) per year, and on slopes with an angle of inclination greater than 20%. The adjustment of fuzzy functions identified 17,327.5 ha with a tendency to recover, and which are therefore strategic areas in the development of ecological corridors. © 2016, Sociedade de Investigacoes Florestais. All rights reserved.40580381

A novel niobium (oxy)nitride-BaCe0.7Zr0.1Y0.2O3-δ composite electrode for Proton Ceramic Membrane Reactors (PCMRs)

The necessity to accelerate green and low carbon technologies, to mitigate the pending energetic crisis, potentiates the urgent search for alternative energy transfer methods. In this regard, Proton Ceramic Membrane Reactors (PCMRs) have shown great potential as a clean alternative for both energy production and the electrochemical synthesis of a wide range of chemical products. One of the most important is that of ammonia, where recent literature has demonstrated the potential use of PCMRs to either synthesize this chemical product or to use it as a fuel, and where suitable new electrodes must be developed. Hence, this work investigates the use of niobium (oxy)nitride (NbNxOy) in combination with proton ceramic conducting materials, as a new category of composite electrode for PCMRs applications. To achieve this goal, firstly, the chemical compatibility of the NbNxOy phase with the well-known proton conducting perovskite, yttrium-doped barium cerate (BaCe0.9Y0.1O3-δ, BCY10), was assessed. By X-ray powder diffraction, BaCe0.7Zr0.1Y0.2O3-δ (BCZY712) was shown to be chemically stable with the NbNxOy phase, surviving up to 850 °C, thus, facilitating the production of an electrolyte supported composite electrode film based on BCZY712-NbNxOy (40–60 vol%). Thermogravimetric experiments combined with X-ray diffraction were also made to assess the thermal stability of the NbNxOy material in both N2 and 2 % H2/N2 atmospheres, revealing that NbNxOy decomposes into its parent oxide in N2, while retaining the pure (oxy)nitride phase in the more reducing conditions. The polarization behavior of the BCZY712-NbNxOy composite electrode was evaluated by electrochemical impedance spectroscopy under different gaseous conditions of H2/N2 and NH3 atmospheres. The overall electrode mechanism was tentatively explained by three main steps, including i) proton incorporation/water release or adsorption/desorption of water, ii) gaseous hydrogen adsorption/desorption, and iii) interfacial transfer reaction of either protons or oxygen-ion vacancies. To the best of our knowledge, this is the first work that reports a detailed chemical compatibility study of niobium (oxy)nitride with a protonic ceramic matrix, while also outlining a detailed electrode mechanism under prospective conditions of hydrogenation/de‑hydrogenation of ammonia.publishe

Sustainability evaluation of a Portuguese “terroir” wine

The challenges of sustainability are transversal to all human activities, and the wine sector has its own role to play in the march for a more sustainable development. The proper definition of the most adequate measures and/or policies must be based on an objective and quantitative evaluation of the sustainability of a product or process. In this work the sustainability of a “terroir” wine is assessed taking into account its life cycle and using the following indicators: carbon and water footprint, material intensity, solid waste generated, worker turnover rate, investment in H&S training and EBITDA. All indicators are expressed per functional unit of 0.75 L of wine. The evaluation used data from the company complemented with data/information from the literature or life cycle inventory databases. To account for climatic variability, data from three consecutive years was used. Average values of 3.51 kgCO2eq and 481.4 L per functional unit were obtained for the carbon and water footprint respectively, both values within the range of values reported in the literature.To Sogrape Vinhos, S.A. for funding Project PP-IJUP2014-SOGRAPE. To FCT, for funding project IF/01093/2014/CP1249/CT0003, research grants IF/01093/2014 and SFRH/BPD/112003/2015, and Center for Innovation in Engineering and Industrial Technology - CIETI, UID/EQU/00305/2013. Financial support of POCI-01-0145-FEDER-006939 (Laboratory for Process Engineering, Environment, Biotechnology and Energy - LEPABE, UID/EQU/00511/2013) funded by FEDER through COMPETE2020-POCI and by national funds through FCT.info:eu-repo/semantics/publishedVersio

The anisotropic Ashkin-Teller model: a renormalization group study

The two-dimensional ferromagnetic anisotropic Ashkin-Teller model is investigated through a real-space renormalization-group approach. The critical frontier, separating five distinct phases, recover all the known exacts results for the square lattice. The correlation length $(\nu_T)$ and crossover $(\phi)$ critical exponents are also calculated. With the only exception of the four-state Potts critical point, the entire phase diagram belongs to the Ising universality class.Comment: 3 ps figures, accepted for publication in Physica

Mills’ syndrome: case report

The syndrome of progressive, ascending or descending hemiplegia, with no significant sensory impairment was first describes by Mills in 1900, which several cases were reported later. However after diagnostic tests and image improvements, the number of reports has shortened. A possible explanation for this shortage is the identification of other diseases that could mimic the clinical picture. Currently, the syndrome has an uncertain nosological status, since it was described based on clinical examination only. We can find this clinical presentation (Mills syndrome) in cases of amyotrophic lateral sclerosis (ALS), predominant upper motor neuron amyotrophic lateral sclerosis (UMN-ALS) and primary lateral sclerosis (PLS), besides its symptomatic (secondary) forms. We describe a case (initial presentation and one year follow-up) of progressive ascending hemiplegia with clinical isolated upper neuron signs and normal sensory examination, discussing its nosological status, electromyographic findings, differential diagnosis and prognosis

On the physico-mechanical, electrical and dielectric properties of mullite-glass composites

Mullite-glass composites were obtained by solid-state reactive sintering of kaolinite clay and kaolin waste mixtures with waste additions up to 100 wt%. The structural and microstructural analysis of starting powders and sintered samples were evaluated by X-ray diffractometry (XRD) and field-emission scanning electron microscopy (FESEM). The mechanical properties were evaluated by measuring the flexural strength of sintered bodies. Electrical properties of the composites were assessed by impedance spectroscopy (at 30 °C and from 400 to 700 °C) in air. A viscous flux mechanism resulting from the glassy phase filled up the open porosity and increased the mechanical strength. Electrical conductivity, dielectric constant and dielectric loss were strongly dependent on the microstructural features, namely glassy phase and porosity. The activation energies (0.89–0.99 eV) for electrical conduction were lower than typical literature values of mullite-based materials. The results indicated that the herein synthesized mullite-glass composites with up to 53.6 wt% mullite are promising low-cost materials for electronics-related applications.publishe

Facile synthesis of oxo-/thioxopyrimidines and tetrazoles C–C linked to sugars as novel non-toxic antioxidant acetylcholinesterase inhibitors

Microwave-assisted synthesis of oxo-/thioxopyrimidines and tetrazoles linked to furanoses with D-xylo and D-ribo configuration, and to a D-galacto pyranose is reported and compared to conventional methods. Reaction of dialdofuranoses and dialdopyranoses with a b-keto ester and urea or thiourea under micro wave irradiation at 300 W gave in 10 min the target molecules containing the 2-oxo- or 2-thioxo-pyrimidine ring in high yield. The tetrazole-derived compounds were obtained in two steps by reaction of the formyl group with hydroxylamine hydrochloride, copper sulfate, triethylamine and dicyclohexylcarbodiimide to give an intermediate nitrile, which was then treated with sodium azide. The use of microwave irradiation in the latter step also resulted in a considerably shorter reaction time (10 min) compared to hours under conventional heating to obtain a complete starting materials conversion. Acetylcholinesterase inhibition ranged from 20% to 80% for compounds concentration of 100 lg/mL, demonstrating the potential of this family of compounds for the control of Alzheimer’s disease symptoms. Most of the compounds showed antioxidant activity in the b-carotene/linoleic acid assay, some of them exhibiting IC50 values in the same order of magnitude as those of gallic acid. The bioactive compounds did not show cytotoxic effects to human lymphocytes using the MTT method adapted for non-adherent cells, nor geno toxicity determined by the short-term in vitro chromosomal aberration assay.info:eu-repo/semantics/publishedVersio

Battery-like behavior of Ni-ceria based systems: synthesis, surface defects and electrochemical assessment

NiO, CeO2 and respective composites are extensively used in energy storage devices due to mostly their high electrochemical activity. However, the assessment of battery-like behavior of Ni-ceria based systems comprising (Ni or Gd)-doped ceria combined with NiO seems to be neglected in the literature. In this work, NiO and ceria-based solid solutions composite powders were obtained by a co-precipitation synthesis method. The structure and particle size of the calcined powders were investigated by X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM), respectively. Oxidative states of composites were inspected by X-ray photoelectron spectroscopy (XPS). The electrochemical performance of powders was evaluated by cyclic voltammetry, galvanostatic charge-discharge and impedance spectroscopy. Refinement of the XRD patterns showed that powders have nanosized crystallites and mean size of particles within 20 – 70 nm were revealed by FESEM. The improved specific capacity of the NiO-CeO2 electrode material (about 2.5 times higher than that of NiO-CGO at 5 mV s−1) is due to an increase in Faradic reactions taken place on its surface with a higher fraction of defects (namely Ni3+, Ce3+ and oxygen vacancies), as determined by XPS. The superior electrochemical performance of the NiO-CeO2 electrode is also confirmed by electrochemical impedance spectroscopy.publishe