Physicochemical characterisation of the exopolysaccharides of Streptococcus thermophilus ST‐143

Exopolysaccharides (EPS) excreted by lactic acid bacteria used in the dairy environment are either liberated into the medium (free EPS) or remain attached to the cells (capsular EPS). After batch fermentation of Streptococcus thermophilus ST‐143 at pH 6.0, three EPS fractions were isolated and purified: free EPS (EPS_f), capsular‐derived EPS (EPS_cd) and the entire total EPS (EPS_total). EPS_f and EPS_cd were uncharged, consisted of rhamnose, galactose, glucose and N‐glucosamine in different amounts and showed a molecular mass of 2.6 × 10⁶ Da (EPS_f) and, in case of EPS_cd, 7.4 × 10³ Da and 1.4 × 10⁵ Da in a ratio of 9: 1. Intrinsic viscosity of the polymers was 1.14 mL mg^?1 (EPS_f), 0.06 mL mg^?1 (EPS_cd) but 1.23 mL mg^?1 for EPS_total. The higher functionality of the entire EPS that was also observed in shear rheology measurements indicates that the presence of small capsular‐derived EPS facilitates the entanglement of the larger polymeric carbohydrates of the EPS_f fraction.     

On the modelling of stability problems for thin plates with functionally graded structure

A conjunction of local apparent properties with a global design of structural elements is motivation for applying composites, which have space varying effective properties. This contribution deals with analysis of dynamics and stability problems for thin composite plates with a smooth and a slow gradation of macroscopic properties. The formulation of two mathematical models of these plates, based on a tolerance averaging technique, cf. Wo?niak et al. [18], is the aim of the paper. The general results are applied to the analysis of some special problems.     

On robustness of camera identification algorithms

Multimedia Tools and Applications - In this paper we consider the problem of a privacy threat enabling tracing digital cameras by the analysis of pictures they produced. As thousands of images are...     

Enhancements of SDR-Based FPGA System for V2X-VLC Communications

This pilot study focuses on a real measurements and enhancements of a software defined radio-based system for vehicle-to everything visible light communication (SDR-V2X-VLC). The presented system is based on a novel adaptive optimization of the feed-forward software defined equalization (FFSDE) methods of the least mean squares (LMS), normalized LMS (NLMS) and QR decomposition-based recursive least squares (QR-RLS) algorithms. Individual parameters of adaptive equalizations are adjusted in real-time to reach the best possible results. Experiments were carried out on a conventional LED Octavia III taillight drafted directly from production line and universal software radio peripherals (USRP) from National Instruments. The transmitting/receiving elements used multistate quadrature amplitude modulation (M-QAM) implemented in LabVIEW programming environment. Experimental results were verified based on bit error ratio (BER), error vector magnitude (EVM) and modulation error ratio (MER). Experimental results of the pilot study unambiguously confirmed the effectiveness of the proposed solution (longer effective communication range, higher immunity to interference, deployment of higher state QAM modulation formats, higher transmission speeds etc.), as the adaptive equalization significantly improved BER, MER and EVM parameters. The best results were achieved using the QR-RLS algorithm. The results measured on deployed QR-RLS algorithm had significantly better Eb/N0 (improved by approx. 20 dB) and BER values (difference by up to two orders of magnitude).     

Characterization of ideal and disordered InAS/GaSb heterostructures for infrared technologies

A series of microscopic calculations have been performed for a family of type II InAs/GaSb multiple quantum well (MQW) heterostructures. The resulting stationary state solutions were used to investigate the infrared spectra and scattering cross-sections due to clusters of isovalent anion defects. The absorption coefficient exhibited a polarization dependence which has not previously been observed for heterostructures made from these materials, in that the spectral features and magnitudes matched closely for radiation polarized parallel and perpendicular to the interfacial planes. The magnitude of the scattering cross-section was generally consistent with the defect density and the localization of the carrier wave functions. However, exceptions from this trend were identified in the proximity of the interfaces for electron scattering. Lattice relaxation around defects was observed to reduce scattering for both holes and electrons although the changes in the cross-section due to this phenomenon were not as pronounced as for equivalent superlattice systems. The collective results highlight significant differences between the optical and dynamical properties of MQW and superlattice systems.     

Bandstructure effects and near-resonant enhancement of the third-order susceptibility in GaAs-AIAs superlattices

We present the results of a full-scale calculation of the third-order susceptibility (χ⁽³⁾), for GaAs-AIAs superlattices with a period of 10 lattice constants, illustrating its frequency dependence, and the importance of a full-scale calculation in order to achieve an accurate assessment of χ⁽³⁾. We also show how bandstructure effects, such as valley-mixing, can affect this enhancement.     

A reduced order model of Molten Carbonate Fuel Cell: A proposal

The mathematical model of the Molten Carbonate Fuel Cell (MCFC) is presented. The new approach for modeling the voltage of MCFC is proposed. Electrochemical, thermal, electrical and flow parameters are collected in the 0-D mathematical model. The aim was to combine all cell working conditions in as a low number of factors as possible and to have the factors relatively easy to determine. A validation process for various experimental data was made and adequate results are shown. The presented model was validated for various fuel mixtures in relatively wide ranges of parameters. A distinction is made between the “design-point” and “off-design operation”.     

FINEMET-type thin films deposited by HiPIMS: Influence of growth and annealing conditions on the magnetic behaviour

Results concerning the influence of deposition conditions (effective power, P_eff, pulse length, τ, and working gas pressure, p) as well as of thermal treatments on the properties of Fe_73.5Cu₁Nb₃Si_15.5B₇ thin films, deposited by high power impulse magnetron sputtering (HiPIMS) technique, are presented. The P_eff, τ and p values were varied in the range of 30–90 W, 4–20 μs and 8–60 mTorr respectively. According to the XRD analysis, in as-deposited state, all the prepared samples are amorphous. For P_eff constant the coercive magnetic field, H_c, increases whit τ, while for τ constant H_c decreases when P_eff increases. The lowest H_c values have been obtained after the samples were annealed at temperatures between 450 °C and 480 °C, when the average size of the α-Fe(Si) grains and the crystalline volume fraction increase about 45% and 20% respectively.     

Impact of enzyme on quality of blackcurrant and plum juices

The aim of work was optimization of technology of cloudy blackcurrant and plum juices production. The major concern was the increase of product cloudiness and its stability. Red fruit were processed with commercial pectinolytic preparations (Pectinex BE Colour, Pectinex BE XXL, and mixture of Rohapect PTE with Rohament PL). The effect of enzyme dose, maceration time and addition of ascorbic acid (in case of plum) on juices quality was investigated. Using single enzyme, either polygalacturonase or pectin lyase did not allow obtaining juices with high enough turbidity, however appropriate enzyme mixture allowed to obtain cloudy juice with the turbidity of at least 230 NTU for blackcurrant and above 500 NTU for plum juice. The best pressing-yield for blackcurrant was achieved with polygalacturonase and pectin lyase, 65 g/100 g after 1 h and 74 g/100 g after 4 h of pectinolysis. The macerating mixture gave about 58÷59 g/100 g yield, irrespectively of enzymation time. Pressing-yield of plum juices was in the range of 94÷97 g/100 g due to the fact that practically only skins were retained on pressing cloth. Addition of ascorbic acid (AA) during plum juice processing in quantity of 500 mg/kg had protective effect on anthocyanins. In control plum juices range of anthocyanins contents were 12.1÷16.5 mg/100 ml while in juice with AA addition even 21.4÷24.5 mg/100 ml.     

Heavy metal behaviour in peat - A mineralogical perspective

The mineralogical composition of a 40 cm subsurface layer of transitional mire ‘Bagno Bruch’ (southern Poland) polluted with atmospheric dust was studied using scanning electron microscopy. The mire is located 9 km to the east of a zinc smelter on the northern limit of industrial Upper Silesia in southern Poland. Concentrations of zinc, lead and cadmium reach values of 494, 238 and 16 mg kg⁻¹, respectively, in the peat layer.Inorganic particles in the peat were grouped into two main categories based on their origin: air dust particles of anthropogenic- and natural sources, and authigenic minerals that originated within the mire. Anthropogenic particles comprise an important part of the inorganic particles in the peat. As they are typically enriched in heavy metals, their stability is critical to controlling metal mobilities. Spheroidal aluminosilicate fly-ash particles are the most common- and most stable anthropogenic pollutants. Partially dissolved Pb-bearing particles (sulphides, chlorides and oxides) and ZnS occur as trace components throughout the peat profile. The prolonged existence of the particles made them susceptible to gravitational relocation in the peat and limits the biogeochemical cycling of the constituent elements. The least resistant Fe (hydro)oxides release Zn and minor amounts of Mn, Mg and Sn due to reductive dissolution. The released Zn is immobilized in the form of ZnS spherules, 1-3 μm in diameter, approximately 10 cm further down in the profile.The investigation shows that the behaviour of trace elements in polluted peatland is controlled by mineral dissolution/precipitation processes. The formation of authigenic minerals (ZnS, barite, gypsum) indicates complex redox conditions and element redistribution in the transitional mire.