Mechanical properties of reactive powder concrete containing high volumes of ground granulated blast furnace slag

The mechanical properties (flexural strength, compressive strength, toughness and fracture energy) of steel microfiber reinforced reactive powder concrete (RPC) were investigated under different curing conditions (standard, autoclave and steam curing). Portland cement was replaced with ground granulated blast furnace slag (GGBFS) at 20%, 40% and 60%. Sintered bauxite, granite and quartz were used as aggregates in different series. The compressive strength of high volume GGBFS RPC was over 250 MPa after autoclaving. When an external pressure was applied during setting and hardening stages, compressive strength reached up to 400 MPa. The amount of silica fume can be decreased with increasing amount of GGBFS. SEM micrographs revealed the tobermorite after autoclave curing.     

Effects of Nisin and Lysozyme on Growth Inhibition and Biofilm Formation Capacity of Staphylococcus aureus Strains Isolated from Raw Milk and Cheese Samples

Effects of nisin and lysozyme on growth inhibition and biofilm formation capacity of 25 Staphylococcus aureus strains isolated from raw milk (13 strains) and cheese (12 strains) were studied. Nisin was tested at concentrations between 0.5 and 25 μg/ml; the growth of all strains was inhibited at 25 μg/ml, but the resistances of strains showed a great variation at lower nisin concentrations. In contrast, lysozyme tested at concentrations up to 5.0 mg/ml showed no inhibition on the growth of strains. Nisin used at the growth inhibitory concentration prevented the biofilm formation of strains, but strains continued biofilm formation at subinhibitory nisin concentrations. Lysozyme did not affect the biofilm formation of 19 of the strains, but it caused a considerable activation in the biofilm formation capacity of six strains. Twelve of the strains contained both biofilm-related protease genes (sspA, sspB, and aur) and active proteases; eight of these strains were nisin resistant. These results suggest a potential risk of S. aureus growth and biofilm formation when lysozyme is used in the biopreservation of dairy products. Nisin can be used to control growth and biofilm formation of foodborne S. aureus, unless resistance against this biopreservative develops.     

Gold Extraction from an Oxide Ore by Thiourea Leaching with Hydrogen Peroxide as an Oxidant

Russian Journal of Non-Ferrous Metals - In this study, the effects of thiourea (CH4N2S) on the efficiency of gold dissolution were investigated for the extraction of gold from an oxide gold ore of...     

Investigation of the effects of different heat treatment parameters on the corrosion and mechanical properties of the AlSi10Mg alloy produced with direct metal laser sintering

In this study, AlSi10Mg samples produced by the direct metal laser sintering (DMLS) method were applied to heat treatment with different parameters (stress relief and T6). Heat-treated and as-built samples were subjected to intergranular corrosion test according to BS EN ISO 11846 standard. Hardness, tensile, electrical conductivity, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and weight loss tests were applied to the samples. The corrosion, electrical conductivity, and mechanical properties of the DMLS-AlSi10Mg material were investigated in detail depending on the heat-treatment parameters.     

A Computational Investigation of the Thermohydraulics of an EGS Project

A numerical analysis of the thermohydraulics of an enhanced geothermal system project is presented. The rock structures are modelled as porous medium, based on the computationally obtained hydraulic fracturing data of other authors. The influence of the domain size, grid resolution, temporal resolution and the discretization scheme is assessed to obtain a highly accurate numerical solution under the prevailing modelling assumptions. Based on the numerical model, different production scenarios are investigated and discussed. The relative positioning of the injection and production ports is also analyzed. It is shown that there is a considerable potential for optimizing the production rate and the port configuration to obtain the most favorable results for the production temperature, investment costs and operation costs.     

Enhanced corrosion resistance and surface characterization of anodized 7075 Al

Protection of Metals and Physical Chemistry of Surfaces - In this study, we aim to enhance physical and chemical properties of 7075 aluminum via anodizing. For this purpose, convenient potential,...     

Surface polymerization of iron particles for magnetorheological elastomers

Magnetorheological Elastomers (MREs) are synthesized from silicone RTV (room temperature vulcanizing) elastomer with magnetically soft iron particles. The iron particle concentration of the MREs is 70 wt %. To reduce the effect of oxidation on the MREs, the ATRP technique is used for surface polymerization of iron particles with fluorinated styrene as monomer. The mechanical properties of MREs are characterized using a mechanical testing instrument, and the surface coated polymer is characterized using Fourier transform infrared spectroscopy (FTIR), X‐ray energy dispersive spectrometry (XEDS), differential scanning calorimetry (DSC), and the alignment of iron particles within MRE was characterized using scanning electron microscopy (SEM). The MRE samples are characterized using the mechanical testing instrument at 0 Tesla (off–state) and applied magnetic field from 0.46 Tesla to 0.62 Tesla (on–state). The required force at 0.62 Tesla increased approx. 3% to achieve 20% strain after 72 h of oxidation for surface coated MRE. On the other hand, the required force for non‐surface coated MREs at 0.62 Tesla increased up to 17% to achieve 20% strain after 72 h of oxidation. MREs with surface coated iron particles have higher oxidation stability based on the force–displacement test results, and MREs have excellent potential to be used as intelligent materials with high durability for a vibration isolator. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ochratoxin A and Brewing Technology: A Review

Ochratoxins are a hazardous group of mycotoxins produced as secondary metabolites by several fungi of the Aspergillus and Penicillium families. Ochratoxins have been detected and determined in foods and beverages, including barley, malt and beer, at ppb levels. Varied analytical methods have been developed for the detection of ochratoxin A [OTA] in cereals and beer. Ochratoxin A has hazardous effects on health and has been classified within group 2B, as a possible human carcinogen by IARC. Scientists have expressed great concern about the presence of ochratoxin A in foods. In this article, chemical structure, biosynthesis by microorganisms, analytical methods for testing, regulations, changes during brewing, and detoxification of OTA, are reviewed. Beer poses very little risk as a source of ochratoxin in the diet.