Bromate, often detected in drinking water, is associated with a significant risk of cancer. Catalytic reduction has been recognized as an effective treatment technique to remove ions by reducing them ...over metal catalysts in the presence of a reducing agent, usually hydrogen. This work aims to synthesize metallic magnetic nanoparticles of iron oxide (FeO) and mixed iron oxides with manganese (MnFeO), cobalt (CoFeO), and copper (CuFeO) coated with carbon via chemical vapor deposition (C-MNP) to be applied as catalysts to the reduction of bromate in water. The use of magnetic nanoparticles coated with carbon enables catalyst recovery via magnetic separation and takes advantage of the catalytic properties of the carbon materials. The iron particles proved to be the most promising catalysts for the reduction of bromate into bromide, the highest removal being obtained with the CFeO@CVD750 sample, resulting in a 99% conversion after 120 min of reaction under the conditions tested. Due to its magnetic nature, the catalytic material was easily removed after the reaction and applied in four consecutive cycles without losing its catalytic properties. These results highlight the great potential of carbon-coated magnetic nanoparticles for reducing bromate in water.
•Self-compacting concretes containing EAF slag are shown to be of good quality.•The accelerated ageing test results are positive in all concrete samples.•The limestone fines content of the concrete ...greatly influences its durability.•The EAF slag concretes exposed to marine environments show satisfactory behavior.
The durability of structural concrete mixes prepared with electric steelmaking aggregates is tested for use in normal and aggressive environments. Samples of “pumpable” and “self-compacting” concrete mixes are shown to have good physical characteristics, mechanical properties and dimensional stability. The mixes were subjected to severe freezing-thawing and drying-wetting tests up until deterioration, to assess their resistance to inland environments. Real immersion in the tidal zone of a harbor and laboratory tests on reinforcement bar corrosion were also performed to evaluate the quality and utility of this sort of concrete in marine environments. The behavior of the mixes in these exposure tests was satisfactory, confirming their suitability for use in structural applications exposed to different environments.
In this work, we report the experimental and theoretical first molecular electronic hyperpolarizability (
) of eleven π-conjugated oxazoles compounds in toluene medium. The Hyper-Rayleigh Scattering ...(HRS) technique allowed the determination of the experimental dynamic
values, by exciting the compounds with a picosecond pulse trains from a Q-switched and mode-locked Nd:YAG laser tuned at 1064 nm. Theoretical predictions based on time-dependent density functional theory level using the Gaussian 09 program package were performed with three different functionals (B3LYP, CAM-B3LYP, and M06-2X), to calculate both static and dynamic theoretical
values. Good accordance was found between the experimental and theoretical values, in particular for the CAM-B3LYP and M06-2X functionals.
Lipases are the most widely used enzymes in biocatalysis, and the most utilized method for enzyme immobilization is using hydrophobic supports at low ionic strength. This method allows the one step ...immobilization, purification, stabilization, and hyperactivation of lipases, and that is the main cause of their popularity. This review focuses on these lipase immobilization supports. First, the advantages of these supports for lipase immobilization will be presented and the likeliest immobilization mechanism (interfacial activation on the support surface) will be revised. Then, its main shortcoming will be discussed: enzyme desorption under certain conditions (such as high temperature, presence of cosolvents or detergent molecules). Methods to overcome this problem include physical or chemical crosslinking of the immobilized enzyme molecules or using heterofunctional supports. Thus, supports containing hydrophobic acyl chain plus epoxy, glutaraldehyde, ionic, vinylsulfone or glyoxyl groups have been designed. This prevents enzyme desorption and improved enzyme stability, but it may have some limitations, that will be discussed and some additional solutions will be proposed (e.g., chemical amination of the enzyme to have a full covalent enzyme-support reaction). These immobilized lipases may be subject to unfolding and refolding strategies to reactivate inactivated enzymes. Finally, these biocatalysts have been used in new strategies for enzyme coimmobilization, where the most stable enzyme could be reutilized after desorption of the least stable one after its inactivation.
•Lipases immobilization on hydrophobic supports via interfacial activation is described in this review•This protocol permits the one step immobilization, purification, stabilization and hyperactivation of lipases•Lipases may be released from the support under certain conditions•Intermolecular crosslinking may prevent enzyme release•Heterofunctional supports prevent enzyme release but they have some limitations•There are many ways of taking full advantage of the new heterofunctional supports
The paper reviews the shear buckling resistance models for plate girders and proposes an improved model based on the EN 1993–1-5 formulation for evaluating the failure load of a plate girder loaded ...in shear. The code-based shear resistance models proposed by Basler, Rockey et al. and Höglund are discussed. The Höglund model is further expanded, and the location of the plastic hinges in the flanges is modified, taking into account the relative sizes of the web, flanges, and transverse and longitudinal stiffeners, to produce a consistent tension field model of the plate girder shear post-buckling behaviour.
A database was created from the experimental tests on thin steel plate girders loaded in shear that were conducted over time. The proposed model's results are validated by comparison with the shear resistances reported for this database's 261 tests. Statistical analysis shows that the proposed modifications are as accurate as the EN1993–1-5 formulation with the extra advantage of preventing several unsafe results for steel plate girders with high flange-to-web ratios.
•Comprehensive analysis of steel plate girders shear behaviour up to failure.•Review of the current and past design model codes for shear resistance.•Assessment of the rotate field model and presentation of enhancements.•Extensive database of 261 experimental tests performed on plate girders loaded in shear up to failure.•Comparation of test results with code-model results and statistical evaluation.
The long-term application of road salts has led to a rise in surface water chloride (Cl–) concentrations. While models have been used to assess the potential future impacts of continued deicing ...practices, prior approaches have not incorporated changes in climate that are projected to impact hydrogeology in the 21st century. We use an INtegrated CAtchment (INCA) model to simulate Cl– concentrations in the Tioughnioga River watershed. The model was run over a baseline period (1961–1990) and climate simulations from a range of GCMs run over three 30-year intervals (2010–2039; 2040–2069; 2070–2099). Model projections suggest that Cl– concentrations in the two river branches will continue to rise for several decades, before beginning to decline around 2040–2069, with all GCM scenarios indicating reductions in snowfall and associated salt applications over the 21st century. The delay in stream response is most likely attributed to climate change and continued contribution of Cl– from aquifers. By 2100, surface water Cl– concentrations will decrease to below 1960s values. Catchments dominated by urban lands will experience a decrease in average surface water Cl–, although moderate compared to more rural catchments.
Simple electrostatic models have been shown to successfully rationalize the magnetic properties of mononuclear single molecule magnets based on f-elements and even to predict the direction of the ...magnetic anisotropy axis in these nanomagnets. In this Article, we go a step forward by showing that these models, conveniently modified to account for the covalency effects, are able to predict not only the easy axis direction but also the three components of the magnetic anisotropy. Thus, by using a lone pair effective charge (LPEC) model we can fully reproduce the angular dependence of the magnetic susceptibility in single crystals of pentamethylcyclopentadienyl-Er-cyclooctatetraene single-ion magnet. Furthermore, the parametrization of the ligands obtained in this study has been extrapolated to successfully reproduce spectroscopic data of a set of mononuclear lanthanoid complexes based on the same kind of ligands, thus emphasizing the predictive character of this model.
By depositing ceria on the surface of yttrium-stabilized zirconia (YSZ) nanocrystals and further activation under high-temperature reducing conditions, a 13% mol. CeO2/YSZ catalyst structured as ...subnanometer thick, pyrochlore-type, ceria-zirconia islands has been prepared. This nanostructured catalyst depicts not only high oxygen storage capacity (OSC) values but, more importantly, an outstandingly stable redox response upon oxidation and reduction treatments at very high temperatures, above 1000 °C. This behavior largely improves that observed on conventional ceria-zirconia solid solutions, not only of the same composition but also of those with much higher molar cerium contents. Advanced scanning transmission electron microscopy (STEM-XEDS) studies have revealed as key not only to detect the actual state of the lanthanide in this novel nanocatalyst but also to rationalize its unusual resistance to redox deactivation at very high temperatures. In particular, high-resolution X-ray dispersive energy studies have revealed the presence of unique bilayer ceria islands on top of the surface of YSZ nanocrystals, which remain at surface positions upon oxidation and reduction treatments up to 1000 °C. Diffusion of ceria into the bulk of these crystallites upon oxidation at 1100 °C irreversibly deteriorates both the reducibility and OSC of this nanostructured catalyst.
The objective of the study is to analyze the technical suitability of using secondary materials from three waste flows (construction and demolition waste (CDW), Waelz slag and municipal solid waste ...incineration (MSWI) bottom ash), under the regulations and standards governing the use of materials for road construction. A detailed technical characterization of the materials was carried out according to Spanish General Technical Specifications for Road Construction (PG3). The results show that Waelz slag can be adequate for using in granular structural layers, while CDW fits better as granular material in roadbeds. Likewise, fresh MSWI bottom ash can be used as roadbed material as long as it does not contain a high concentration of soluble salts. This paper also discusses the adequacy of using certain traditional test methods for natural soils when characterizing secondary materials for use as aggregates in road construction.
Bacterial biofilms are highly difficult to control, hence significant economic resources have been allocated to develop strategies to eradicate them. This study evaluated the effect of an enzymatic ...treatment to be used as a cleaning product to control the presence of biofilms. Two different materials used in the food industry, polystyrene and stainless steel, were tested using Salmonella Typhimuirum and Cronobacter sakazakii. Biofilm formation was carried out by inoculating the surfaces with a standardized concentration of 4 log (CFU cm−2) and incubated for 48 hr with renewal of nutrients. The biofilm formation and subsequent enzymatic treatment were quantified using fluorescence microscopy and the conventional culture method. The enzymatic treatment showed significant reductions of 2–3 log (CFU cm−2) in biofilm cells, which was attributed to the degradation of the extracellular matrix and the further detachment of both microorganisms. The maximum biofilm detachment obtained with the preventive formula was 46.67%; however, this percentage could be increased by applying an aggressive treatment or by adding a subsequent disinfection step that would eliminate adhered microbial cells. Further, the enzymatic cleaning treatment could be exploited as a potent technology to control bacterial adherence and biofilm formation in the food industry.
Enzymatic treatment is capable of removing the biofilm matrix so that the subsequent disinfection can be more effective.
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