Impact of sonication at 20 kHz on Microcystis aeruginosa, Anabaena circinalis and Chlorella sp

Blooms of toxic cyanobacteria such as Microcystis aeruginosa periodically occur within wastewater treatment lagoons in the warmer months, and may consequently cause contamination of downstream water and outages of the supply of recycled wastewater. Lab-scale sonication (20 kHz) was conducted on suspensions of M. aeruginosa isolated from a wastewater treatment lagoon, and two other algal strains, Anabaena circinalis and Chlorella sp., to investigate cell reduction, growth inhibition, release of microcystin and sonication efficiency in controlling the growth of the M. aeruginosa. For M. aeruginosa, for all sonication intensities and exposure times trialled, sonication led to an immediate reduction in the population, the highest reduction rate occurring within the initial 5 min. Sonication for 5 min at 0.32 W/mL, or for a longer exposure time (>10 min) at a lower power intensity (0.043 W/mL), led to an immediate increase in microcystin level in the treated suspensions. However, prolonged exposure (>10 min) to sonication at higher power intensities reduced the microcystin concentration significantly. Under the same sonication conditions, the order of decreasing growth inhibition of the three algal species was: A. circinalis > M. aeruginosa > Chlorella sp., demonstrating sonication has the potential to selectively remove/deactivate harmful cyanobacteria from the algal communities in wastewater treatment lagoons.     

Low temperature sintering of lead-free Bi0.5(Na0.82K0.18)0.5TiO3 piezoelectric ceramics by co-doping with CuO and Nb2O5

Effect of excess CuO additive on the sintering behavior and piezoelectric properties of Bi_0.5(Na₈₂K_0.18)_0.5TiO₃ ceramics was investigated. The addition of small amount of excess CuO as low as 1 mol% was quite effective to lower the sintering temperature (T_s) of BNKT ceramics down to 975 °C while their piezoelectric properties were degraded by Cu doping. However, the electric field-induced strain was markedly enhanced by further addition of Nb₂O₅ with CuO without elevating T_s. The normalized strain S_max/E_max of 427 pm/V was obtained with a specimen sintered with 0.02 mol CuO and 0.03 mol Nb₂O₅ in excess.     

Global optimization in property‐based interplant water integration

This article presents a new global optimization method for the interplant water integration based on properties to characterize streams with numerous components. The problem is formulated as an mixed‐integer non‐linear programming (MINLP) model based on a superstructure that involves all possible options of interest (i.e., reuse and recycle in the same and to other plants and a set of shared treatment units). This formulation exhibits multiple local minima, and to overcome this problem, this article proposes effective branching rules in addition to two new reformulations for the upper bound (integer feasible solution) and the lower limit (relaxed solution), which are incorporated into a spatial branch and bound procedure to handle the bilinear terms in the model. The objective consists in finding the configuration with the minimum total annual cost. Results show that the global optimal solution (involving significant reductions in the fresh water consumption) is reached in few iterations and short central processing unit (CPU) time. © 2012 American Institute of Chemical Engineers AIChE J, 59: 813–833, 2013     

Ein optoanalytisches Verfahren zur Bestimmung der Faserverteilung und ‐orientierung in stahlfaserverstärktem UHFB

An Optoanalytic Method for the Determination of the Distribution and Orientation of Fibres in Steel Fibre Reinforced UHPC Micro steel fibres were often used to improve the ductility as well as to increase the tensile and bending strength of ultra high performance concrete (UHPC). The knowledge about the distribution and orientation of fibres is important to predict the load capacity of structures made of fibre reinforced UHPC. It is also relevant from economic and ecological point of view. Due to the multiplicity of influences, such as geometry, concrete properties and manufacture technology, it is necessary to investigate the distribution and orientation of fibres for individual application. At Leipzig University a practicable method was developed to determine the distribution and orientation of micro steel fibres in UHPC.     

Ermüdungsfestigkeit von hochfestem Beton unter Druckbeanspruchung

Fatigue behaviour of high strength concrete under compression. The fatigue strength of high performance concrete (HPC) was experimentally investigated with ca. 170 specimens. The results show that the fatigue behaviour of HPC differs from that of the normal strength concrete (NSC). In the regions of maximum compressive stress level higher than the elasticity limit, the fatigue strength of HPC seems smaller than those of NSC. In the remaining regions the behaviour of HPC is comparable with the behaviour of NSC. The stress redistribution within the compression zone with different stress amplitude seems also smaller than those of NSC. Additional investigations are necessary in order to formulate design rules for constructions made of HPC.     

Enhanced Solar‐to‐Hydrogen Generation with Broadband Epsilon‐Near‐Zero Nanostructured Photocatalysts

The direct conversion of solar energy into fuels or feedstock is an attractive approach to address increasing demand of renewable energy sources. Photocatalytic systems relying on the direct photoexcitation of metals have been explored to this end, a strategy that exploits the decay of plasmonic resonances into hot carriers. An efficient hot carrier generation and collection requires, ideally, their generation to be enclosed within few tens of nanometers at the metal interface, but it is challenging to achieve this across the broadband solar spectrum. Here the authors demonstrate a new photocatalyst for hydrogen evolution based on metal epsilon‐near‐zero metamaterials. The authors have designed these to achieve broadband strong light confinement at the metal interface across the entire solar spectrum. Using electron energy loss spectroscopy, the authors prove that hot carriers are generated in a broadband fashion within 10 nm in this system. The resulting photocatalyst achieves a hydrogen production rate of 9.5 µmol h^?1 cm^?2 that exceeds, by a factor of 3.2, that of the best previously reported plasmonic‐based photocatalysts for the dissociation of H₂ with 50 h stable operation.     

A study of emission characteristic,deposits, and lubrication oil degradation of a diesel engine running on preheated vegetable oil and diesel oil

Vegetable oils are always considered as the potential sources since the renewable and alternative fuels have been being paid attention by all countries in the world based on the strategies of the environmental pollution reduction. The aim of this experimental study is to evaluate the effects of as-used fuels on emission characteristics, deposit formation, and lubricating oil (LO) degradation of a 4 stroke-4 cylinder diesel engine running on preheated vegetable oil and diesel oil. All tests were conducted under 2000 rpm of engine speed, and 80hp of power within different periods of time depending on the test purposes. The ICP-MS analyzer was used to measure the LO quality through the parameters of kinematic viscosity, density, and metal concentrations on the basis of ASTM D5185-09 standard after every 25 hours of the test duration. Meanwhile, the emission characteristics were tested by an exhaust analyzer after every 50 hours, and deposit formation on piston crown and piston groove was evaluated by the assistance of Scanning electron microscopy (SEM) after 300 hours of the test. Besides, the thorough analysis related to the relationship between deposit formation, the degradation of the engine LO and emission characteristics were presented.     

Recent advances in two-dimensional transition metal dichalcogenides as photoelectrocatalyst for hydrogen evolution reaction

Hydrogen gas has been attracting significant interest as an emerging energy source that is clean, sustainable, and renewable. Primarily, it can be produced via photoelectrochemical (PEC) splitting of water using solar energy. Among the various catalysts employed for the photoreduction of water, two-dimensional transition metal dichalcogenides (2D-TMDs) are inarguably the best candidates toward industrialization because they have extraordinary physical, optical, and electric properties, and are solution-processable at low costs. In this review, we focus on the development of 2D-TMDs and their PEC properties toward the hydrogen evolution reaction. First, the synthesis and properties of 2D materials are summarized and discussed. Next, the strategies for improving the photocatalytic activity of the 2D material-based catalysts for water splitting are thoroughly investigated. Finally, the remaining challenges and direction for the future development of 2D-TMDs in PEC catalysis-derived hydrogen evolution reaction are addressed. © 2020 Society of Chemical Industry