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.     

An introduction to the studies of reliability of systems using the Weibull proportional hazards model

The paper presents the way of solving problems concerning reliability with respect to concomitant variables. The Cox models are discussed and Weibull's proportional hazards model is defined. The paper shows how to estimate the model parameters and statistically verify the results.     

The influence of fault occurrence on multiaccess system throughput

A probabilistic performance model of a multiaccess computer system with three-levelled hierarchical structure is presented. A measure of the level capabilities is introduced and the effects of fault occurrence on system throughput are analysed. It is proved that the model is sufficient for determination of system throughput in stationary conditions.     

Mathematical analysis of the kinetics of hydrogenating depolymerization of benzene-insoluble coal extract fraction in the absence of catalyst

The paper analyses some kinetic models for the process of hydrogenating depolymerization of benzene-insoluble fractions of coal in the absence of a catalyst. Considerations as to the direction of decomposition of benzene-insoluble fractions to oils are presented.     

DRYING KINETICS AND PARTICLE RESIDENCE TIME IN SPRAY DRYING

A unique experimental equipment for extensive trials on the spray drying kinetics and particles residence time involving “in situ” analysis of the properties of continuous and dispersed phases was designed, built, and tested. Advanced experimental techniques (including laser techniques) to determine current parameters of spray drying process (temperature, humidity, moisture content) and current structure of spray (particle size distribution, particle velocities, etc.) were employed. Full scale spray drying tests of baker's yeast and maltodextrin enabled identification of the effect of process parameters on drying kinetics and spray residence time in the tower. Quantitative relationship describing spray drying kinetics as a function of atomization ratio and drying agent temperature were determined. The experimental results proved that spray residence time was controlled by atomization ratio and airflow rate. Drying kinetics in spray drying process is presented for the first time in the literature.     

Extracting zinc from oxidized minerals via an induction furnace

This article describes the mineral characteristics, thermodynamic analyses, kinetic tests, and coordinated mass and energy balance of a zinc extraction process for oxidized minerals. The reduction, performed in an induction furnace with a load of 3 kg, permits almost complete zinc extraction in the temperature range 1,650–1,673 K after 90 minutes. The process is thermodynamically advantageous, shows small irreversibility, and yields two interesting by-products: exhaust gas with high CO content and iron alloys. The discard slag does not contain toxic components, and the zinc oxide produced meets the requirements for hydrometallurgical processing.     

Heteropolyanions doped polyimine—Preparation and spectroscopic properties

It is demonstrated that aromatic polyimine obtained by the condensation of p-phenylenediamine and terephtalaldehyde can be chemically doped with heteropolyanions of Keggin-type. The spectroscopic studies show that polyimine undergoes protonation. The structural identity of the Keggin units are preserved upon incorporation into the polymer matrix.     

Kinetic analysis of autocatalytic action in the hydrogenating depolymerization of benzene-insoluble fractions of coal extract

This paper analyses, from the standpoint of kinetics, the possibility of autocatalytic effects of the asphaltene formed during the hydrogenating depolymerization of benzene-insoluble fractions. The autocatalytic and linear models were tested against experimental data and it was concluded that the asphaltenes had no autocatalytic function.