Silica coated ferrite nanoparticles: Influence of citrate functionalization procedure on final particle morphology

In this paper, magnetic nanoparticles (Fe₃O₄ and NiFe₂O₄) were coated with a biocompatible silica shell via hydrolysis and condensation of tetraethyl orthosilicate (TEOS) by the Stöber process. Magnetic nanoparticles, prepared by chemical co-precipitation from iron and nickel salts, were functionalized with citric acid, in order to provide their deagglomeration and to enable their coating with silica. The parameters of the functionalization procedure were varied (concentration–pH and type of treatment), in order to examine if and how this particular step of preparation affects the final morphology of the core-shell particles. Transmission electron microscopy, zeta potential and particle size measurements revealed that the morphology and the size of obtained core shell particles depend significantly on the core particle size, and thus on the parameters of the functionalization step.     

Printing of antimicrobial microcapsules on textiles

One of the processes for the application of functional compounds that alter textile properties is encapsulation. In our research, a microencapsulated biocide was used to produce an antimicrobial textile product. Melamine–formaldehyde polymer wall microcapsules with a triclosan core were applied to a cotton fabric by screen printing. Printed samples were dried and cured. The fabric hand properties of washed and unwashed samples were tested and the antibacterial activity against Staphylococcus aureus and Escherichia coli was evaluated. The quantity of free formaldehyde on the printed and washed samples was monitored for 2 months. The results show that microcapsules with triclosan can be successfully applied to a cotton fabric by printing, where they provide good antibacterial protection without substantially changing the fabric properties. The quantity of formaldehyde on the unwashed samples is high and it changes with time; however, it significantly decreases with washing.     

Textiles screen‐printed with photochromic ethyl cellulose–spirooxazine composite nanoparticles

Photochromic compounds change colour on exposure to light, while the reversion may be attributable either to radiation or may be thermal. The use of photochromism on fabrics can provide new opportunities to develop smart textiles; for example, sensors and active protective clothes. Ethyl cellulose‐1,3‐dihydro‐1,3,3,4,5 (and 1,3,3,5,6) ‐pentamethyl‐spiro‐[2H‐indole‐2,3′‐(3H)naphtha(2,1‐b)(1,4)oxazine] composites were prepared by an oil‐in‐water emulsion, solvent evaporation method in order to form easily suspendable and fatigue‐resistant photochromic nanoparticles in screen‐printing paste. Their size was well below 1 μm and did not change substantially over a wide range of dye concentrations. After screen‐printing, a homogenous photochromic layer was built on a cotton substrate surface, which represented substantial blue colour development in CIELab colour space measurements because of ultraviolet light, even at a dye concentration of 0.045% w/w. The addition of a photodegradation inhibitor, Tinuvin 144, further increased the coloration of the printed fabric.     

Modelling of chemical surface acoustic wave sensors and comparative analysis of new sensing materials

Comparative analysis of different, new gas sensing materials in surface acoustic wave chemical sensors is presented. Different gas sensing materials as polyaniline (PANI), Teflon AF 2400, polyisobutylene (PIB), polyepichlorohydrin (PECH) are considered. They are chosen according to the type of gas to be detected and the desired accuracy: Teflon AF 2400 thin film for the detection of CO₂, PANI nanocomposites film that belongs to the group of conductive polymers for the detection of CO, NO₂ and phosgene (COCl₂), and PECH and PIB for the detection of dichloromethane (CH₂Cl₂, DCM). In the analysis, the simple and useful method of the complete analyses of gas chemical sensors is used. The method is based on the electrical equivalent circuit of the surface acoustic wave sensor. The method is very efficient and can be used for the optimal design of CO₂ sensors. The results are compared with those presented in public literature and good agreement is obtained, demonstrating the validity of modelling. Copyright © 2012 John Wiley & Sons, Ltd.     

Fuzzy Modeling of the Permeate Flux Decline during Microfiltration of Starch Suspensions

Flux declines versus time during cross‐flow microfiltration of wheat starch suspensions were modeled using fuzzy logic systems under different conditions of transmembrane pressure, flow rate, and suspension concentration. Fuzzy modeling is one of the most efficient methods for empirical modeling, especially for non‐linear systems, and does not require any prior knowledge about the process. The influence of the process parameters on the dynamic behavior of the permeate flux was determined by comparing the permeate flux decline versus the volume curves, considering a constant value of the volumetric concentration factor during batch cross‐flow filtration. At the transient stages of the filtration process, the permeate flux was shown to be strongly dependent on all process parameters, within the examined range.     

A life cycle energy assessment for biogas energy in Serbia

The aim of this paper was to present the energy flows in the life cycle of biogas utilization systems (cogeneration and transportation), as well as their mutual relations, starting from providing the feedstock for digestion through to end-of-life management of biogas system as fertilizer on agricultural land. This study was carried out through the energy analysis of two scenarios (biogas in cogeneration and biogas in transportation) using performance of Mirotin biogas plant (1 MW) in Serbia. Results obtained in this study have shown that the analyzed scenario (biogas in cogeneration and biogas in transportation) have positive energy balances (52,114 and 53,585 GJ) and these scenarios are sustainable from energetic point of view.     

A Microprocessor-Oriented Algorithm for Adaptive Equalization

Adaptive equalization based on a transversal filter is extremely important for reliable data transmission over the voiceband telephone lines. Unfortunately, implementation of rapidly converging and small residual distortion algorithms on the standard MOS microprocessors or standard-cell MOS VLSI chips is difficult because of their mathematical complexity. In this paper, an adaptive equalization algorithm is proposed which is suitable for cost-effective implementation on MOS microprocessors and standard-cell MOS VLSI chips. It is based on the same principle of delayed decision that was used successfully in delta modulation. It involves no multiplications or analog-to-digital conversion, but is relatively fast and provides a relatively low residual distortion. The proposed algorithm is simulated in both noise-free and noisy environments and is compared to two well-known classical algorithms.     

An Approach to the Triple Branch Selection Diversity Analysis Over Correlated α-μ Fading Channels in the Presence of CCI

In this paper, an approach to derivation of the joint trivariate ??-?? probability density function (pdf) and cumulative distribution function (cdf) expressions will be presented. Capitalizing on this, closed-form expressions for the cdf and pdf at the output of triple branch selective combiner (SC) in the presence of correlated co-channel interference (CCI) will be determined. The main contribution of this paper is generality of our model, since the expressions accommodate arbitrary correlation structures. General results, from this paper, could be reduced to the specific ones for various fading models and types of correlation. Important performance measures like outage probability (Pout) and average output signal-to-interference ratio (SIR) will also be determined and graphically illustrated for various values of existing parameters.