The Study of Ethanol/Water Vapors Permeation through Sulfuric Acid Cross-Linked Chitosan Magnetic Membranes

Sulfuric acid cross-linked chitosan membranes filled with a different amount of magnetite, were prepared. The permeation behavior of ethanol and water vapors in vapor permeation experiments were studied. Permeation rates were measured. Mass transport coefficients were evaluated. The study has been carried out to determine the influence of magnetic powder dispersed inside of the chitosan membrane on ethanol-water separation. The diffusion, fluxes, and permeation coefficients increased with greater amount of magnetite content. The separation factor increased with increasing flux and the best results were achieved for the membrane containing 15% w/w magnetite. The research allows optimizing the preparation procedure of chitosan magnetic membranes cross-linked by sulfuric acid with the best permeation properties.     

Magnetic Mixed Matrix Membranes Consisting of PPO Matrix and Magnetic Filler in Gas Separation

Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and magnetic neodymium powder particles MQP-14-12 have been used for the preparation of magnetic mixed matrix membranes. Permeability diffusion and sorption coefficients of O₂, N₂, and synthetic air components were estimated for homogeneous and heterogeneous membranes using the Time Lag method based on dynamic experiments in a constant pressure system. The influence of magnetic field and magnetic powder particles on the gas transport properties of MMMs was studied. The results showed that the membrane permeation properties were improved with the magnetic neodymium particle filling. It was observed that the magnetic ethylcellulose and poly(2,6-dimethyl-1,4-phenylene oxide) membranes showed higher gas permeability, while their permselectivity and solubility were rather maintained or slightly increased. The results also showed that the magnetic powder addition enhanced gas diffusivity significantly in EC and PPO membranes.     

Metallated conjugated polymers as a new avenue towards high-efficiency polymer solar cells

Bulk heterojunction solar cells have been extensively studied owing to their great potential for cost-effective photovoltaic devices. Although recent advances resulted in the fabrication of poly(3-hexylthiophene) (P3HT)/fullerene derivative based solar cells with efficiencies in the range 4.4-5.0%, theoretical calculations predict that the development of novel donor materials with a lower bandgap is required to exceed the power-conversion efficiency of 10%. However, all of the lower bandgap polymers developed so far have failed to reach the efficiency of P3HT-based cells. To address this issue, we synthesized a soluble, intensely coloured platinum metallopolyyne with a low bandgap of 1.85 eV. The solar cells, containing metallopolyyne/fullerene derivative blends as the photoactive material, showed a power-conversion efficiency with an average of 4.1%, without annealing or the use of spacer layers needed to achieve comparable efficiency with P3HT. This clearly demonstrates the potential of metallated conjugated polymers for efficient photovoltaic devices.     

Removal of nitrogen from industrial wastewaters with the use of algal rotating disks and denitrification packed bed reactor

An attempt was made to use an algal rotating disk system in a two-step biological purification of nitrogen fertilizer industry wastewaters. The proposed method involved the removal of ammonium by Stichococcus bacillaris growing on the rotating disk and of oxidized forms of nitrogen by denitrifying bacteria. The use of a rotating algal disk followed by denitrification bed as the second step of biological treatment removed about 90% of nitrogen from the wastewater. A change of purification sequence resulted in the appearance of NO ⁻₃ and NO⁻₂ in the purified wastewater caused by the activity of nitrifying bacteria accompanying algae in the biological film on the disk. It was found that methanol used as a carbon source for denitrifying bacteria could be replaced by organic matter of algal origin.     

Augmented Lagrangian based reconstruction of non-uniformly sub-Nyquist sampled MRI data

MRI has recently been identified as a promising application for compressed-sensing-like regularization because of its potential to speed up the acquisition while maintaining the image quality. Thereby non-uniform k-space trajectories, such as random or spiral trajectories, are becoming more and more important, because they are well suited to be used within the compressed-sensing (CS) acquisition framework. In this paper, we propose a new reconstruction technique for non-uniformly sub-Nyquist sampled k-space data. Several parts make up this technique, such as the non-uniform Fourier transform (NUFT), the discrete shearlet transform and a augmented Lagrangian based optimization algorithm. Because MRI images are real-valued, we introduce a new imaginary value suppressing prior, which attenuates imaginary components of MRI images during reconstruction, resulting in a better overall image quality. Further, a preconditioning based on the Voronoi cell size of each NUFT data point speeds up the conjugate gradient optimization used as part of the optimization algorithm. The resulting algorithm converges in a relatively small number of iterations and guarantees solutions that fully comply to the imposed constraints. The results show that the algorithm is applicable not only to sub-Nyquist sampled k-space reconstruction, but also to MR image fusion and/or resolution enhancement.     

Quality assessment of gluten-free crackers based on buckwheat flour

Formulation and characterization of new products - gluten-free crackers based on two types of buckwheat flour (refined and wholegrain) are presented in this study. Their proximate composition, content of main antioxidant compounds (polyphenols and tocopherols), antioxidant activity (radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl radicals - DPPH) and sensory quality were analyzed and compared with those of wheat crackers made from refined and wholegrain wheat flours.Protocatechuic acid and ferulic acid were quantified in buckwheat and wheat crackers, while two flavonoids, rutin and quercetin, were quantified only in buckwheat crackers. Content of total phenolics and tocopherols was significantly higher (P < 0.05) in buckwheat crackers in comparison to wheat crackers. Tocopherols in crackers were present in the following order: α- ? γ- > δ-tocopherol. Buckwheat crackers exhibited significantly higher (P < 0.05) radical scavenging activity on DPPH according to their IC₅₀ values.No significant differences were observed in sensory quality of wholegrain buckwheat crackers in comparison to wheat ones. Crackers made from buckwheat flours can broaden the utilization of buckwheat, increase supply of gluten-free products on the market and may be regarded as health-promoting functional foods, especially for celiac disease patients.     

Fabrication of nanoplasmonic arrays with square symmetry using spin-coating method

A spin-coating method was applied for the first time to prepare a colloid monolayer on the optical crossed gratings used as a template. Four polystyrene colloids of various nominal sizes and different surface charges were spin-coated on templates with periods matched to the particles size. Three types of coverage were described depending on the spin-coating parameters and particles type. The optimal coverage was obtained for all four particles sizes. A way of finding the right spin-coating parameters was proposed. The analysis of a coverage capability of polystyrene particles showed that neutral particles have the highest ability to order on the templates used. Large monolayered areas of ordered particles were used as a lithographic mask for generating a pattern of gold nanoparticles with a square symmetry. A few hundred square micrometers large, continuous and fully defect-free areas of gold nanoparticles were produced on the nearly entire surface of the templated substrates.     

TiCp*(OMe)3 versus Ti(OMe)4 in atomic layer deposition of TiO2 with water--ab initio modelling of atomic layer deposition surface reactions

It is a common finding that titanocene-derived precursors do not yield TiO2 films in ALD with water. For instance, ALD with Ti(OMe)4 and water gives 0.5 A/cycle, while TiCp*(OMe)3 does not show any growth (Me=CH3, Cp* = C5(CH3)5). This is apparently in contradiction with the computed reactivity of the ligands: the energetics of hydrolysis of the gas-phase precursor indicate that TiCp*(OMe)3 is more reactive to ligand elimination than Ti(OMe)4. However such a model of precursor reactivity neglects surface reactions such as adsorption, diffusion and desorption, all of which can have an important effect on ALD growth rate. A more accurate model of the surface reaction is needed to find the reason for the different behaviours of Ti(OMe)4 and TiCp*(OMe)3 in the ALD process. The more realistic surface model is a TiO2 slab that is periodic in three dimensions. These calculations reveal that TiCp*(OMe)3 does not chemisorb in the usual way because of extreme crowding of the Ti centre by Cp* and that this prevents ALD growth.     

Performance analysis of dual switched diversity over correlated Weibull fading channels with co‐channel interference

This paper studies the performance of switch and stay combining (SSC) diversity in the presence of co‐channel interference over correlated Weibull fading channels. SSC diversity based on signal‐to‐interference ratio (SIR) is a low‐complexity and a very efficient technique that reduces fading and co‐channel interference influence. New closed‐form expressions for the probability density function and cumulative distribution function of the output SIR's are derived. These formulas are used in a detailed analysis of the average output SIR and outage probability. The influence of fading severity and correlation coefficient on the optimum switching threshold and system performance is investigated. Monte Carlo simulations are performed to verify obtained theoretical results and determine average bit error rate in detecting binary phase‐shift keying (BPSK), differential BPSK and quadrature amplitude modulation signals. Copyright © 2011 John Wiley & Sons, Ltd.     

Indium tin oxide nanorod electrodes for polymer photovoltaics

We have deposited indium tin oxide (ITO) nanorods on glass and glass/ITO substrates by DC sputtering and by e-beam deposition. The properties of the nanorods deposited by different methods and on different substrates have been investigated. The ITO nanorods were also used as an electrode in bulk heterojunction polymer solar cells. We found that the nanorod morphology and sheet resistance had a significant effect on the solar cell performance, with significant improvements in the efficiency compared to commercial ITO film substrates in all cases except for e-beam deposited nanorods on glass that had high sheet resistance. The best power conversion efficiency achieved was 3.2 % (for sputtered ITO nanorods on ITO), compared to 2.1 % for commercial ITO substrates.