Encapsulation of urease in double‐layered hydrogels of macroporous poly(2‐hydroxyethyl methacrylate) core and poly(ethylene oxide) outer layer: fabrication and biosensing properties

Double‐layered hydrogels of super‐macroporous poly(2‐hydroxyethyl methacrylate) (PHEMA) cryogel core and poly(ethylene oxide) (PEO) hydrogel outer layer for encapsulation of the enzyme urease were constructed. The enzyme was entrapped into the pores of PHEMA cryogel by soaking and then the core was covered with a PEO layer. The leaking of urease from the core was prevented when the density of the PEO network was increased by incorporation of the crosslinking agent, poly(ethylene glycol) diacrylate. The hybrid system exhibited a nearly constant enzyme activity with time and maintained its structural integrity after several reactions of hydrolysis of urea. The potential of double‐layered hydrogels containing urease for establishment of water pollution with copper was investigated as well. Copyright © 2011 Society of Chemical Industry     

Lateral Magnetic Near‐Field Imaging of Plasmonic Nanoantennas With Increasing Complexity

The design of many promising, newly emerging classes of photonic metamaterials and subwavelength confinement structures requires detailed knowledge and understanding of the electromagnetic near‐field interactions between their building blocks. While the electric field distributions and, respectively, the electric interactions of different nanostructures can be routinely measured, for example, by scattering near‐field microscopy, only recently experimental methods for imaging the magnetic field distributions became available. In this paper, we provide direct experimental maps of the lateral magnetic near‐field distributions of variously shaped plasmonic nanoantennas by using hollow‐pyramid aperture scanning near‐field optical microscopy (SNOM). We study both simple plasmonic nanoresonators, such as bars, disks, rings and more complex antennas. For the studied structures, the magnetic near‐field distributions of the complex resonators have been found to be a superposition of the magnetic near‐fields of the individual constituting elements. These experimental results, explained and validated by numerical simulations, open new possibilities for engineering and characterization of complex plasmonic antennas with increased functionality.     

Phytochemical study and antiinflammatory properties of Lobelia laxiflora L

Three new piperidine alkaloids were isolated from stems, leaves and flowers of Lobelia laxiflora L. (Campanulaceae). The structures of racem. cis-8,10-diethyl-3,4-dehydrolobelidiol (1), racem. trans-8-ethyl-10-phenyl-3,4-dehydrolobelidiol (2) and racem. cis-8-ethyl-10-phenyl-3, 4-dehydrolobelidiol (3) were established by spectral analyses. The residues obtained from the ethanol extracts from stems (S), leaves (L), and flowers (F) were applied in carrageenan (Car)- and cobra venom (CV)-induced acute inflammation in mice. A suppression of paw edema formation at a dose of 100 mg kg-1 was established. In this study the antiinflammatory potential of Lobelia l. was regarded in connection with the complement system. The sequential activation and assembly into functional units of complement components can proceed via two different pathways, named classical (CP) and alternative (AP). The ability of the residues, nonalkaloid fractions, alkaloid fractions and the three alkaloids at a concentration from 0.125 to 1.0 mg ml-1 to inhibit complement activation and thus to prevent inflammatory process was estimated in vitro in human serum via both pathways. All of them inhibited complement activity with a predominant action on CP.     

Distributed control parallelism in multidisciplinary aircraft design

Multidisciplinary design optimization (MDO) for large-scale engineering problems poses many challenges (e.g. the design of an efficient concurrent paradigm for global optimization based on disciplinary analyses, expensive computations over vast data sets, etc.). This work focuses on the application of distributed schemes for massively parallel architectures to MDO problems, as a tool for reducing computation time and solving larger problems. The specific problem considered here is configuration optimization of a high speed civil transport (HSCT), and the efficient parallelization of the embedded paradigm for reasonable design space identification. Two distributed dynamic load balancing techniques (random polling and global round robin with message combining) and two necessary termination detection schemes (global task count and token passing) were implemented and evaluated in terms of effectiveness and scalability to large problem sizes and a thousand processors. The effect of certain parameters on execution time was also inspected. Empirical results demonstrated stable performance and effectiveness for all schemes, and the parametric study showed that the selected algorithmic parameters have a negligible effect on performance. Copyright © 1999 John Wiley & Sons, Ltd.     

Electrochemical performance of steel in cement extract and bulk matrix properties of cement paste in the presence of Pluronic 123 micelles

The influence of Pluronic P123 (PEO₂₀-PPO₇₀-PEO₂₀) non-stabilized micelles (of 10 nm size) on the corrosion behavior of low-carbon steel in cement extract was studied, using electrochemical impedance spectroscopy (EIS) and potentio-dynamic polarization (PDP). Mercury intrusion porosimetry (MIP) was employed to derive the impact of admixed P123 micelles on porosity and pore-size distribution of cement paste. As far as steel corrosion resistance is concerned, a positive effect was observed, initially denoted to the presence of the polymer itself, rather than the presence of micelles. Further, the P123 micelles were found to result in increased corrosion resistance in the presence of 1 % and 3.5 % NaCl in the alkaline environment of cement extract. There was no significant influence on porosity and pore size distribution of the admixed in cement paste P123 micelles. The observed phenomena are related to self-assembly of the micelles only within higher ionic strength and the presence of chloride, in which case the critical micelle concentration is reduced. At micelles concentration of 0.024 g/l for the chloride-free cement extract (and the solid cement paste specimens, respectively), the medium actually contain unimers that have minimal impact on electrochemical performance and/or microstructural properties. In contrast, with increased ionic strength of the medium (1?3.5 % NaCl and altered ion concentrations resulting from the anodic/cathodic reactions within steel corrosion), the positive effect of 0.024 g/l micelles (and higher of 0.072 g/l) is more pronounced, i.e., increased corrosion resistance and anodic control with external polarization was observed.     

Morphology of an asymmetric ethyleneoxide-butadiene di-block copolymer in bulk and thin films

We present experiments on the melt and crystal morphology of a asymmetric semi-crystalline poly(ethylene/butylene-b-ethyleneoxide) diblock copolymer (PB_h-b-PEO) in bulk as well as in thin films. Simultaneous small- and wide-angle X-ray scattering combined with AFM and TEM images reveal in the melt a bulk morphology of hexagonally packed cylinders of PEO in a PB_h matrix, that transforms into a hexagonal perforated lamellar phase upon crystallization. X-ray reflectivity of thin films of PB_h-b-PEO in the melt indicates wetting layers at the top and bottom interfaces, which force the cylinders in the interior to orient parallel to the substrate. Crystallization of the PEO block leads to roughening of the air/film interface and causes lateral structuring coexisting with planar lamellar layers in thinner films.     

Plasmon-enhanced sub-wavelength laser ablation: plasmonic nanojets

In response to the incident light's electric field, the electron density oscillates in the plasmonic hotspots producing an electric current. Associated Ohmic losses raise the temperature of the material within the plasmonic hotspot above the melting point. A nanojet and nanosphere ejection can then be observed precisely from the plasmonic hotspots.