The Outstanding Contribution of Basal Slip in Substructure Development during Friction Stir Processing of Magnesium Alloys

This research reveals the critical role of basal slip in the substructure development during friction stir processing of a magnesium alloy. In this respect, the intragranular lattice rotation axes are considered to identify the activity of different slip systems. The applied shear strain during the procedure is stored in the matrix through slip-induced rotations at the grain level. The rotations around distinct Taylor axes produce “slip domains” separated by necessary boundaries from the parent grains, significantly contributing in grain refinement. The basal slip is easily activated in grains holding different stored energy; however, the nonbasal slip has a higher dependency on the amount of local applied strain. Determining the contribution of different slip systems in strain accommodation reveals that the basal slip imposes the highest fraction of low-angle boundaries into the microstructure leading to the development of the ultimate grain boundary structure.     

Detection of bacterial endotoxin in food: New planar interdigital sensors based approach

Food poisoning caused by endotoxins or Lipopolysaccharide (LPS) are associated with Gram-negative bacteria. Two major food-borne pathogens, Escherichia coli and Salmonella are examples of Gram-negative bacteria which cause a large number of outbreaks of food poisoning. New types of planar interdigital sensors have been fabricated with different coating materials to assess their response to endotoxins. A carboxyl-functional polymer, APTES (3-Aminopropyltriethoxysilane) and Thionine were chosen to be coated onto FR4 interdigital sensors. The chosen coating materials have carboxylic or amine functional groups, which were optimized to be stable in water. All coated sensors were immobilized with PmB (Polymyxin B) which has specific binding properties to LPS. The sensors were tested with different concentrations of LPS O111:B4, ranging from 0.1 to 1000 μg/ml. Analyses of sensors’ performance were based on the impedance spectroscopy method. The impedance spectra were modeled using a constant phase-element (CPE) equivalent circuit, and a principal component analysis (PCA) was used for data classification. Sensor coated with APTES has shown better selectivity for LPS detection. The experiments were repeated by coating APTES and immobilizing PmB to a new improve designed of novel interdigital sensors (thin film silicon based sensors). These sensors were observed to have better sensitivity and selectivity to the target biomolecules of LPS. Further experiments were conducted to study the effect of different coating thickness on sensor sensitivity, selectivity and stability. Different food samples contaminated with endotoxin were also tested to verify that the interdigital sensing approach is able to be used for endotoxin detection.     

Quartzite tailings in civil construction materials: a systematic review

Clean Technologies and Environmental Policy - The inadequate management of waste from the mining industry can lead to several environmental problems. For instance, the extraction of quartzite, an...     

Decontamination of powdery and granular foods using Continuous Wave UV radiation in a dynamic process

The purpose of this study was to investigate the potential of Continuous Wave UV radiation, applied in a dynamic process, to reduce Enterobacteriaceae counts in powdery and granular foods. Several food matrices were inoculated with a test strain (Escherichia coli LMG 8063) and radiated for 1 h with UV (254 nm, 2.88 mW/cm²). The particles were constantly homogenized under the UV source. Depending on the food matrix, reductions of 0.7–4.8 log cycles were obtained. For meringue chunks, a storage period of 20 h after inoculation prior to UV treatment caused a smaller reduction of the test strain (2.7 log cycles) than when radiation was applied immediately after inoculation (4.8 log cycles). Different initial contamination levels were tested. Higher inoculation levels tended to yield lower reductions. The results demonstrate that Continuous Wave UV radiation can be applied for microbial decontamination of specific powdery and granular food products under continuous homogenization.