Design Criteria for Non-Orthogonal Space–Time Block Codes in Multipath Channels

We consider the problem of designing high rate space–time block codes in multipath fading channels. For this, both minimizing the effect of the self-interference induced by the code itself, and mitigating the inter-symbol-interference induced by the channel have to be addressed. We translate the problem into an equivalent problem of designing a constrained code in a single-path channel with more antennas, and argue that design criteria derived in single-path apply when optimizing this constrained code. Here we concentrate on an analytic measure pertinent to mutual information maximization and BER-performance optimization. The design program is successfully applied to rate one linear space–time transmissions from four transmit antennas. A family of discrete permutations of the transmitted sequences are considered. Performance is optimized within this family, and the results are seen to effect directly both mutual information and error performance.     

Preparation conditions and swelling equilibria of dextran hydrogels prepared by some crosslinking agents

Crosslinking reactions of Dextran (Dx) (M_n of 2.0×10⁶ g mol⁻¹) with some selective Cl-, P- and N-containing functional monomers such as epichlorohydrin (ECH), phosphorus oxychloride (POC1₃) and N,N′-methylenebisacrylamide (MBAM) were carried out in the basic aqueous solutions (2.8 N NaOH) at 25-50 °C. The optimum conditions of the effective swelling and crosslinking for the each system studied were found in copper (CuCl₂·2H₂O) solution. The percent swelling, equilibrium swelling, initial rate of swelling, swelling rate of constant, equilibrium water content, and diffusion type and constant values were evaluated for Dx/crosslinker (CL) systems at 1 mg/100 ml copper (CuCl₂·2H₂O) solution. A substantial difference of these parameters observed for the various Dx/CL systems was explained by the effect of nature of crosslinking agents on the mechanism of crosslinking and swelling processes. It was shown that S_eq and M_c values increase depending on the nature of CLs in the following order: ECH>MBAM>POCl₃. General scheme and proposed mechanism of crosslinking reactions in the Dx/CL systems were also described.     

Comparison of electrofishing and NORDIC gillnets for sampling littoral fish in boreal lakes

Parallel sampling of fish, using electrofishing and NORDIC multimesh gillnets, was performed in the littoral areas of eight boreal lakes. Some fish species were caught only by electrofishing (e.g. bullhead, Cottus gobio (L.); burbot, Lota lota (L.)), while some were caught only with gillnets (e.g. pikeperch, Stizostedion lucioperca (L.); smelt, Osmerus eperlanus (L.)). The fish species that were caught with both methods (e.g. perch, Perca fluviatilis (L.) exhibited gear-specific length distributions. A combination of NORDIC gillnetting (passive gear) and electrofishing (active gear) is suggested to reasonably well cover the entire species composition in the littoral zones (≈ 0–3 m depth) of boreal lakes. This gear combination is recommended for evaluating the ecological status of lakes within the European Water Framework Directive.     

Adsorption characteristics of clay adsorbents – sepiolite,kaolin and synthetic talc – for removal of Reactive Yellow 138:1

Adsorption characteristics of three clay adsorbents – sepiolite, kaolin and synthetic talc – were investigated to determine their applicability to remove an anionic reactive dye – Reactive Yellow 138:1 – from a water stream. Results showed that synthetic talc had the highest maximum monolayer adsorption capacity of 10.07 mg/g, followed by kaolin (3.73 mg/g) and sepiolite (3.23 mg/g), for the removal of Reactive Yellow 138:1. Synthetic talc and sepiolite removed dyes from aqueous solutions mainly through physical adsorption depending on the surface area. By contrast, the adsorption mechanism of kaolin was strongly influenced by the anion exchange mechanism. Zeta potential analysis revealed that the adsorption capacity of clay adsorbents increased under acidic rather than alkaline conditions, owing to protonation of the clay surface. Moreover, synthetic talc was successfully regenerated by heating at more than 400°C, effectively restoring its original adsorption capacity.     

Hierarchically Ordered Supramolecular Protein-Polymer Composites with Thermoresponsive Properties

Synthetic macromolecules that can bind and co-assemble with proteins are important for the future development of biohybrid materials. Active systems are further required to create materials that can respond and change their behavior in response to external stimuli. Here we report that stimuli-responsive linear-branched diblock copolymers consisting of a cationic multivalent dendron with a linear thermoresponsive polymer tail at the focal point, can bind and complex Pyrococcus furiosus ferritin protein cages into crystalline arrays. The multivalent dendron structure utilizes cationic spermine units to bind electrostatically on the surface of the negatively charged ferritin cage and the in situ polymerized poly(di(ethylene glycol) methyl ether methacrylate) linear block enables control with temperature. Cloud point of the final product was determined with dynamic light scattering (DLS), and it was shown to be approximately 31 °C at a concentration of 150 mg/L. Complexation of the polymer binder and apoferritin was studied with DLS, small-angle X-ray scattering, and transmission electron microscopy, which showed the presence of crystalline arrays of ferritin cages with a face-centered cubic (fcc Fm3¯m) Bravais lattice where lattice parameter a = 18.6 nm. The complexation process was not temperature dependent but the final complexes had thermoresponsive characteristics with negative thermal expansion.     

In vitro hydrolysis and magnesium release of poly(d,l‐lactide‐co‐glycolide)‐based composites containing bioresorbable glasses and magnesium hydroxide

Magnesium is important for both bone growth and cartilage formation. However, the postoperative intake of antibiotics such as quinolones may cause a reduction in magnesium levels in tissue. The addition of magnesium to scaffolds may therefore be beneficial for the regeneration of osteochondral defects. In this study, porous composite scaffolds were produced by gas foaming of poly(d ,l ‐lactide‐co‐glycolide) (PLGA) rods with magnesium‐containing bioresorbable glasses and magnesium hydroxide as fillers. The in vitro hydrolytical degradation of the composite scaffolds in Tris buffer was followed over a 10‐week period. Mg²⁺ was released in a controlled manner from the scaffolds with varying release profiles between the different materials. Higher glass content resulted in a reduced mass loss compared to scaffolds with lower glass content. As a result of the foaming method, the scaffolds shrank initially, without evidence that the addition of hydrophilic fillers would decrease the initial shrinkage. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42646.     

Inexpensive discrete atomistic model technique for studying excitations on infinite disordered media: The case of orientational glass ArN2

Excitations of disordered systems such as glasses are of fundamental and practical interest but computationally very expensive to solve. Here, we introduce a technique for modeling these excitations in an infinite disordered medium with a reasonable computational cost. The technique relies on a discrete atomic model to simulate the low‐energy behavior of an atomic lattice with molecular impurities. The interaction between different atoms is approximated using a spring‐like interaction based on the Lennard‐Jones potential, but the method can be easily adapted to other potentials. The technique allows to solve a statistically representative number of samples with low computational expense and uses a Monte Carlo approach to achieve a state corresponding to any given temperature. This technique has already been applied successfully to a problem with interest in condensed matter physics: the solid solution of N₂ in Ar. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and characterization of electroactive films based on benzo(a)pyrene

The polycyclic aromatic hydrocarbons (PAHs) are a group of compounds that might have practical applications due to their graphene-like properties. Derivatized PAHs can self-assemble in liquid crystal form. The chemical synthesis of large size PAHs can however be complicated and problematic. Electrochemical synthesis of PAHs molecules was studied in this work by cyclic voltammetry. Benzo(a)pyrene was used as the monomer. The resulting electroactive films consist of different PAHs in both size and symmetry. We call this mixture poly(benzopyrene) (PBP). The synthesis conditions of PBP were optimized to obtain thick and electrochemically stable films. The best film quality was achieved by potential scanning in propylene carbonate at low scan rate resulting in continues polymer growth during 10 scans giving approx. a 1 μm thick PBP film. During p- and n-doping studies the reduction and oxidation peaks were observed at 1.0 V and −1.6 V, respectively, with an electrochemical band gap of approx. 2.6 eV. The in situ UV–vis characterization of the PBP films was made by applying a constant potential with increasing steps. The optical band gap was approx. 2.5 eV and the absorption maximum was observed at ca. 420 nm. During p- and n-doping new induced bands were formed in the range 575–600 nm. UV–vis spectroscopy indicate that PBP mainly consist of units consisting of more than 40 carbon atoms and large number of π-electrons.     

Land use impacts of industries and products in the Finnish economy: A comparison of three indicators

The sustainability aspects of land use were assessed with an environmentally extended input-output model of Finland in 2002. The main economic industries and products causing land use were identified and the impacts were estimated with three indicators: biocapacity, human appropriation of net primary production (HANPP) and ecosystem degradation potential (EDP). The results correlated well with expert assessments on the threats to biodiversity, although the influence of animal farming was not clear in all indicators. Most of the domestic land use was caused by final demand outside Finland. Based on a simplified trade balance, Finland was a net exporter of land area, mainly through wood products. Two thirds of the domestic land use was driven by export production. Therefore a regional consumption based approach is not sufficient to mitigate and control the environmental impacts of land use even in a developed country like Finland.     

Electrochemical preparation of oligo(azulene) on nanoporous TiO<Subscript>2</Subscript> and characterization of the composite layer

A nanoporous oligo(azulene)-TiO₂ (OAz-TiO₂) composite layer was formed by electrochemical oxidation of azulene (Az) on a nanoporous ITO/TiO₂ electrode. Polymerization was performed in tetrabutylammonium hexafluorophosphate electrolyte salt dissolved in acetonitrile. The electrochemical and optical properties of the composite layer were studied by cyclic voltammetry (CV) and in situ UV–vis spectroelectrochemistry. The chemical and crystalline structure of the layer was studied by FTIR and X-ray diffraction (XRD) spectroscopy techniques and the morphology by Scanning Electron Microscopy. The TiO₂ layer was found to have a catalytic activity on the polymerization of Az. The CV experiments in monomer-free electrolyte solution demonstrated the electron donor property of OAz by its p-doping and the electron accepting property of TiO₂ by the large reduction current in the negative potential region. The FTIR and XRD spectroscopic measurements showed the well-defined anatase structure of TiO₂ with inclusion of OAz. A composite layer was formed rather than a bilayer structure. The in situ UV–vis spectroelectrochemical measurements gave evidence of a higher delocalization and easier movement of the π-electrons in the composite layer than in pure poly (azulene).