Functional properties of Lactobacillus acidophilus metabolites

BACKGROUND: This study addressed the characteristics of metabolites synthesized by Lactobacillus acidophilus 5e2, with particular attention paid to exopolysaccharides, biosurfactants, proline peptidases and antibacterial compounds. RESULTS: The strain Lb. acidophilus 5e2 synthesizes low‐molecular‐mass polysaccharides (340 kDa) constituted by glucose, galactose and glucosamine at a ratio of 3.3:2.8:1.0, as well as biosurfactants with a molecular mass of 32 kDa built from a protein fraction, a polysaccharide fraction and phosphate groups. It additionally synthesizes extra‐ and intracellular proline peptidases, including prolyl endopeptidase and thermostable low‐molecular‐mass (<3.5 kDa) compounds with antimicrobiological activity against Escherichia coli strains. CONCLUSION: The strain Lb. acidophilus 5e2 may be applied to the production of functional food. Copyright © 2009 Society of Chemical Industry     

Optimization of a parallel permutation testing function for the SPRINT R package

The statistical language R and its Bioconductor package are favoured by many biostatisticians for processing microarray data. The amount of data produced by some analyses has reached the limits of many common bioinformatics computing infrastructures. High Performance Computing systems offer a solution to this issue. The Simple Parallel R Interface (SPRINT) is a package that provides biostatisticians with easy access to High Performance Computing systems and allows the addition of parallelized functions to R. Previous work has established that the SPRINT implementation of an R permutation testing function has close to optimal scaling on up to 512 processors on a supercomputer. Access to supercomputers, however, is not always possible, and so the work presented here compares the performance of the SPRINT implementation on a supercomputer with benchmarks on a range of platforms including cloud resources and a common desktop machine with multiprocessing capabilities. Copyright © 2011 John Wiley & Sons, Ltd.     

Heat transfer and pressure drop during flow boiling of pure refrigerants and refrigerant/oil mixtures in tube with porous coating

The experimental stand and procedure for flow boiling investigations are described. Experimental data for pure R22, R134a, R407C and their mixtures with polyester oil FUCHS Reniso/Triton SEZ 32 in a tube with porous coating and smooth, stainless steel reference tube are presented. Mass fraction of oil was equal to 1% or 5%. During the tests inlet vapour quality was set at 0 and outlet quality at 0.7. Mass velocity varied from about 250 to 500 kg/m²s. The experiments have been conducted for average saturation temperature 0 °C. In the case of flow boiling of pure refrigerants, the application of a porous coating on inner surface of a tube results in higher average heat transfer coefficient and simultaneously in lower pressure drop in comparison with the flow boiling in a smooth tube for the same mass velocity. Correlation equation for heat transfer coefficient calculation during the flow boiling of pure refrigerants inside a tube with porous coating has been proposed.     

Induction of apoptosis in human endothelial cells by nanodiamond particles

Carbon nanoparticles are a promising material which finds application in different fields in industry and medicine. For medical applications, biocompatibility of nanoparticles is of critical importance because a lot of medical implants are coated by carbon coating. Our previous results showed that nanoparticles may induce increased production of ROS by the cells so we decided to checked if nanopowders can induce apoptosis. Apoptosis was quantified by double-staining with acridine orange and ethidium bromide. For comparison, we identified apoptotic cells with annexin V-FITC/propidium iodide. Our data demonstrate that treatment of the cells with diamond nanopowders may induce apoptosis and necrosis and this effect is dependent on the time of treatment and concentration of the nanopowders. The highest level of apoptotic cells was observed after incubation with Ultrananocrystalline Detonation Diamond (UDD) suggesting that the size is the main determinant of nanoparticle cytotoxicity.     

Probabilistic model for the annual number of storm overflow discharges in a stormwater drainage system

The paper presents an attempt to develop a probabilistic model for predicting an annual number of storm overflow discharges. Forecasting the occurrence of an overflow discharge event involved the application of the logistic regression, which does not require the development of complex hydrodynamic catchment models. The performed calculations showed that the logistic regression model can be successfully used to evaluate the performance of the emergency overflow weir. The resultant logit model eliminates the necessity to develop hydrodynamic models, to conduct continuous measurements of the flow intensity in the stormwater drainage system and to collect detailed information on the characteristics of the subcatchments within the analyzed catchment. The hydrodynamic model was used to simulate the annual number of discharges. The analysis of the results demonstrated that they are in the range of stochastic values, which indicates an application-related character of the method.     

Adjoint-based optimization of thermo-fluid phenomena in welding processes

A method is developed for optimizing the complex thermo-fluid phenomena that occur in welding processes where fluid convection is present. A mathematical model of a typical welding problem which includes conservation of mass, momentum and energy, and assumes that the process is steady in the frame of reference moving with the heat source is considered. An optimal control problem in which the heat input from the heat source is determined to ensure a prescribed geometry of the weld is formulated and solved. The problem is solved with a gradient-based optimization approach in which the gradient (sensitivity) of the cost functional with respect to the control variables is determined using a suitably defined adjoint system. An important aspect of the problem is that it is of the free-boundary type. Therefore it is necessary to use methods of the shape calculus to derive the adjoint equations. A number of computational results which validate our approach and feature qualitatively different flow patterns in problems with different material properties are presented.