Influence of processing on stability,microstructure and thermoelectric properties of Ca3Co4 − xO9 + δ

Due to high figure of merit, Ca₃Co_4 ? xO_9 + δ (CCO) has potential as p-type material for high-temperature thermoelectrics. Here, the influence of processing including solid state sintering, spark plasma sintering and post-calcination on stability, microstructure and thermoelectric properties is reported. By a new post-calcination approach, single-phase materials were obtained from precursors to final dense ceramics in one step. The highest zT of 0.11 was recorded at 800 °C for CCO with 98 and 72% relative densities. In situ high-temperature X-ray diffraction in air and oxygen revealed a higher stability of CCO in oxygen (～970 °C) than in air (～930 °C), with formation of Ca₃Co₂O₆ which also showed high stability in oxygen, even at 1125 °C. Since achievement of phase pure high density CCO by post-calcination method in air is challenging, the phase stability of CCO in oxygen is important for understanding and further improvement of the method.     

Corrosion of Metallic and Structural Elements Exposed to Acid Mine Drainage (AMD)

Mining equipment and structural elements (e.g. bridges, mining exploration equipment), which are mainly made of steel and concrete, undergo corrosion processes that are strongly accelerated in these extremely acidic environments, with the further aid of acidophilic bacteria that act as catalysts.     

The effect of external flow on the feeding currents of sessile microorganisms

Microscopic sessile suspension feeders live attached to surfaces and, by consuming bacteria-sized prey and by being consumed, they form an important part of aquatic ecosystems. Their environmental impact is mediated by their feeding rate, which depends on a self-generated feeding current. The feeding rate has been hypothesized to be limited by recirculating eddies that cause the organisms to feed from water that is depleted of food particles. However, those results considered organisms in still water, while ambient flow is often present in their natural habitats. We show, using a point-force model, that even very slow ambient flow, with speed several orders of magnitude less than that of the self-generated feeding current, is sufficient to disrupt the eddies around perpendicular suspension feeders, providing a constant supply of food-rich water. However, the feeding rate decreases in external flow at a range of non-perpendicular orientations due to the formation of recirculation structures not seen in still water. We quantify the feeding flow and observe such recirculation experimentally for the suspension feeder Vorticella convallaria in external flows typical of streams and rivers.     

Chemical Expansion Due to Hydration of Proton‐Conducting Perovskite Oxide Ceramics

The crystal structures of proton‐conducting BaZr_1?xY_xO_3?x/2 (BZY05–BZY20) and BaCe_0.8Y_0.2O_2.9 (BCY20) during hydration/dehydration has been studied by in situ high‐temperature X‐ray diffraction and thermal analysis. A contraction/expansion of the crystal lattice associated with dehydration/hydration was observed for all materials at elevated temperatures and the polymorphic phase transition temperatures of BaCe_0.8Y_0.2O_2.9 were depressed by lowering the vapor pressure of water. A thermodynamic formalism is introduced to describe the chemical expansion associated with the hydration of oxygen vacancies in acceptor‐doped oxides. A conventional point defect model was applied to describe the lattice strain associated with the hydration. The chemical expansion is discussed with respect to the available volumetric data on the hydration of proton‐conducting oxide materials and its likely impact on ceramic fuel cells/hydrogen separation membranes utilizing a proton‐conducting electrolyte.     

Effect of biological and chemical oxidation on the removal of estrogenic compounds (NP and BPA) from wastewater: an integrated assessment procedure

A major source of the wide presence of EDCs (Endocrine Disrupting Compounds) in water bodies is represented by direct/indirect discharge of sewage. Recent scientific literature reports data about their trace concentration in water, sediments and aquatic organisms, as well as removal efficiencies of different wastewater treatment schemes. Despite the availability of a huge amount of data, some doubts still persist due to the difficulty in evaluating synergistic effects of trace pollutants in complex matrices. In this paper, an integrated assessment procedure was used, based on chemical and biological analyses, in order to compare the performance of two full scale biological wastewater treatment plants (either equipped with conventional settling tanks or with an ultrafiltration membrane unit) and tertiary ozonation (pilot scale).Nonylphenol and bisphenol A were chosen as model EDCs, together with the parent compounds mono- and di-ethoxylated nonylphenol (quantified by means of GC-MS). Water estrogenic activity was evaluated by applying the human breast cancer MCF-7 based reporter gene assay. Process parameters (e.g., sludge age, temperature) and conventional pollutants (e.g., COD, suspended solids) were also measured during monitoring campaigns.Conventional activated sludge achieved satisfactory removal of both analytes and estrogenicity. A further reduction of biological activity was exerted by MBR (Membrane Biological Reactor) as well as ozonation; the latter contributed also to decrease EDC concentrations.     

Element contents in leaves of four plant species (birch, mountain ash, fern and spruce) along anthropogenic and geogenic concentration gradients

Forty samples each of leaves of birch (Betula pubescens Ehrh.), European mountain ash (Sorbus aucuparia (L.)) and bracken fern (Pteridium aquilinum (L.) Kuhn) as well as spruce needles (Picea abies (L.) Karsten) were collected along a 120 km south-north transect running through Norway's largest city, Oslo. Concentrations of 25 chemical elements (Ag, Au, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Sr, Ti, and Zn) as well as loss on ignition for the 4 sample materials are reported. The decline of input of sea spray with distance from the coast, geology, pH and anthropogenic contamination all played a role for the observed element concentrations in the leaves. Although growing under exactly the same natural conditions each plant species displayed quite unique uptake characteristics. Plant-species dependency and individual differences in the reaction of the plant leaves to different element sources make the investigated species of very limited value as bioindicators of anthropogenic activities. Anthropogenic contamination influences plant-leaf element content within a limited distance ( approximately 20 km) from the source.     

Current Trends in Pretreatment and Fractionation of Lignocellulose as Reflected in Industrial Patent Activities

The pretreatment process to disintegrate lignocellulose and to fractionate its three main components hemicellulose, cellulose, and lignin, is a crucial step to enable sustainable and economic value chains based on biomass feedstock. This review provides an overview of the recent patenting activities on pretreatment. Most of these activities focus on optimization of different known processes to improve economics, such as increased catalyst efficiency, effluents recirculation, or lignin valorization. However, also a number of patents and demonstration activities based on emerging concepts for pretreatments are observed.