Biofilm formation by lactobacilli and resistance to stress treatments

We investigated biofilm formation by six lactobacilli isolates and tested the resistance of biofilm and planktonic Lactobacillus plantarum B1 and Lactobacillus paracasei W1 to ethanol (ET) and acetic acid (AA). The viability of both isolates was considerably affected by ET, with a higher reduction observed in the planktonic cells, whereas AA was harmful only to L. paracasei W1. Cells that had intact (Syto^® 9⁺PI⁻) and compromised (Syto^® 9⁻PI⁺) membranes, and adopted intermediate states with different concentrations of the probes, i.e., Syto^® 9⁺PI⁺ and Syto^® 9⁻PI⁻, were identified following flow cytometry. We linked Syto^® 9⁺PI⁺ to the planktonic cells and clarified on Syto^® 9⁻PI⁻ cells, which after being sorted could regain growth better in biofilm cells. Based on confocal laser scanning microscopy, numerous cells had damaged membranes in the ET-treated biofilm, while half the cells in the AA-treated biofilm maintained their membrane integrity.     

Utilisation of textile wastes for the production of geotextiles designed for erosion protection

Textile waste was used for production of thick ropes designed for the protection of slopes against sliding and erosion. For the production of ropes, scraps of insulating materials produced from poor quality wool and scraps of nonwoven manufactured from blend of recycled fibres were applied. The ropes were installed on the slope in a disused gravel pit. Stabilisation of the slope and behaviour of the materials used were analysed during two vegetation seasons. Investigations confirmed the usefulness of the technology for the protection of steep slopes.     

Application of waste products from agricultural-food industry for production of rigid polyurethane-polyisocyanurate foams

Solid parts of the wheat slops (90% w/w of dry mass and 10% w/w of water) were applied as a filler (5–30% w/w in relation to the sum of polyisocyanate and polyol masses) in PUR-PIR composition. Six foams containing different amounts of slops were prepared by this method and then, their physical–mechanical properties i.e. apparent density, compressive strength, brittleness, after-combustion residue, stability of linear dimensions, change of volume, loss in mass (48 h, temp 120 °C), softening point, content of the closed cells and absorbability of water were determined. Moreover, the foams were subjected to thermogravimetric and infrared analyses.     

Microstructure and Corrosion Behavior of Hot-Deformed and Cold-Strained High-Mn Steels

The electrochemical corrosion properties of 26Mn-3Si-3Al and 27Mn-4Si-2Al austenitic steels in two different states were studied in 0.1 M H₂SO₄ and 3.5% NaCl using potentiodynamic polarization tests. The effect of cold deformation on the microstructure and corrosion behavior of steels was analyzed. In acid solution, both steels exhibited lower corrosion resistance than in chloride solution independently on the steel state (hot-rolled, cold-worked). Cold deformation decreases the corrosion resistance, though this effect is smaller than the effect of chemical composition related to the combined Al + Si addition. All steels showed the evidence of pitting corrosion. The intensive dissolution of Fe and Mn takes place in the acid medium.     

A Comparison of Surface Tension,Viscosity, and Density of Sn and Sn–Ag Alloys Using Different Measurement Techniques

This work is aimed at comparing several methods for the measurement of physical properties for molten Sn and Sn–Ag alloys, namely, surface tension, density, and viscosity. The method used for viscosity in this work is the modified capillary method. For surface tension and density, the data used for comparison were previously measured using the maximum bubble pressure method and the dilatometer technique, respectively, for four Sn–Ag alloys having (3.8, 32, 55, and 68) at% Ag. The results are compared with those obtained using a new method based on a fluid draining from a crucible under the influence of gravity, designated the Roach–Henein (RH) method. This new method enables the determination of these three physical properties in one set of measurements. Liquid Sn was used as well as two liquid Sn–Ag alloys having (3.8 and 34.6) at% Ag with the RH method. It was determined that the RH method may be used to simultaneously obtain surface tension, viscosity, and density and that the errors associated with these measurements were similar to those obtained using traditional and separate techniques. Comparisons of the measured viscosity and surface tension to those predicted using thermodynamic models will also be presented. Finally a comparison of mixing model predictions with the experimentally measured alloy surface tension and viscosity is also presented.     

A 99 line code for discretized Michell truss optimization written in Mathematica

The main purpose of the paper is to provide an easy-to-use code for topological optimization of the least weight trusses, written in the Mathematica programming language. The main idea of the presented approach consists in using a fixed ground structure and the linear programming formulation of the optimization problem. The solver is based on the fast interior point method. The strong effort is done to create the effective generator of the computational model utilizing the high regularity of the ground structure and the high sparsity of the geometric matrix. The efficiency and reliability of the algorithm is confirmed in several numerical tests. Due to a linear programming formulation of the optimization problem the method presented in the paper assures finding the global optimum, hence it may be considered as the useful tool for verification of results obtained in other ways. The appended complete Mathematica code of the program developed will be supplied by the Publisher on SpringerLink.