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We studied the deformation behaviour of γTi-54.5%Al single crystal at temperatures ranging from 200°C to 700°C along [153] orientation, where the major operative slip system is $\frac{1}{2} \langle 110]({\bar 1}11)$. During this temperature regime, deformation microstructure consists of long heavily pinned screw dislocations. Serrated plastic flow has been observed at 500°C, the serration amplitude decreases with strain. The combination of the strain ageing and stress relaxation experimental results demonstrate for the first time the Portevin–Le Châtelier type instability in TiAl single crystal. [ABSTRACT FROM AUTHOR]

• Zero valent iron nanoparticles prepared for the removal of Cr(VI). • Ultrasound-assisted synthesis at 20 kHz yields to highest surface area. • Faster Cr(VI) reduction of sonicated nanoparticles than ones prepared by stirring. • Co-precipitation of Cr(III) and Fe ions in the form of chromite. • Efficient industrial wastewater treatment by ultrasound-prepared Fe nanoparticles. Reductive zero-valent iron nanoparticles were prepared for the treatment of Cr(VI) solutions. The ferric ions reduction by borohydride was carried out through mechanical stirring or ultrasound irradiation either in an ultrasonic bath or in a 20 kHz cup-horn reactor. The prepared materials have been characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and N 2 adsorption-desorption at 77 K. The microscopic observations showed iron nanoparticles with diameter in the range 40 nm–80 nm, arranged in chain aggregates regardless the variation of the preparation method. The ultrasonic synthesis allowed to obtain higher BET specific surface area (99 m2.g−1 for nanoparticles prepared in ultrasonic bath and 145 m2 g−1 for the ones prepared by probe sonication) than the ones of samples synthesized in silent conditions (22 m2.g−1). The Cr(VI) ions removal in pure water solution was found significant at acidic pH. The removal kinetics modeled by pseudo first order, are linearly proportional to the BET surface areas. They are rapid (< 30 min to attain equilibrium), and decrease as increasing the Cr(VI) concentration and as decreasing the iron nanoparticles dose. Cr(VI) ions were removed by reduction and co-precipitation of Cr(III) in the form of chromite at pH> 7. The iron nanoparticles were tested for the treatment of metal surface processing wastewater. For such treatment, they have proven to be efficient for removing Cr(VI) together with Ni(II) ions. The iron nanoparticles prepared by 20 kHz ultrasonic probe have been found more effective for Cr(VI) removal than any kind of iron nanoparticles conventionally prepared. [ABSTRACT FROM AUTHOR]

Microbial mats are commonly observed in estuaries and in salt marshes but they only rarely represent a significant surface involved in salt production. In the Sečovlje salt works in Northern Adriatic, a microbial mat known as the "petola" covers the bottom of salt crystallising pans, highly influencing salt composition and salt production processes. Throughout the year the petola is subjected to numerous co-varying factors that drive changes in its structure and the microbial community. Seasonal modifications were investigated via various methods (cryo-HRSEM, XRD, elemental analysis, carbohydrate content, bacterial community structure). This study provides knowledge on microbial mat compositional characteristics and functional roles in response to seasonal variation in environmental conditions. The in situ characterisation (close-to its natural hydrated state) of the three-dimensional microstructure provides precise information about dominating filamentous cyanobacterium Coleofasciculus chthonoplastes and extracellular polymer secretion (EPS) organisation. This is the first study to address how microbial mat composition and structure, especially 3D EPS network (and microbial diversity), affects the salt production processes within a hypersaline environment., (Copyright © 2018 Elsevier B.V. All rights reserved.)