Influence of Gaseous Media Flow in the Dual Ar-H<Subscript>2</Subscript>-H<Subscript>2</Subscript>O/air Atmosphere Setup on the Scale Growth Kinetics of Crofer 22APU Ferritic Stainless Steel

The problem of gaseous media distribution within the metallic interconnects in solid oxide fuel cells (SOFCs) and its influence on the oxidation resistance of the applied materials is currently of great interest. In the presented work, an influence of gas flow within the dual Ar-H₂-H₂O/air atmosphere experimental setup on the oxidation behavior of the Crofer 22APU ferritic stainless steel was investigated. Examination of the sample oxidized for 1000 h in temperature of 800 °C revealed the presence of coaxial regions on the scale surface, with the differences in scale’s thicknesses in those regions being clearly visible. Additionally, the morphology of the surface changed significantly in a function of the radial distance from the sample’s center. To further examine the phenomena of uneven gas distribution, a model of the dual-atmosphere setup was created, using Ansys Workbench software. Obtained results suggest that the correlation between scale morphology and distribution of temperature and pressure on the sample’s surface, created by gas flow in the system, can be justified.     

Detection methodology based on target molecule-induced sequence-specific binding to a single-stranded oligonucleotide

We have recently developed a mix-and-read format homogeneous antigen peptide based assay for detection of the antibodies (Tian, L.; Heyduk, T. Anal. Chem. 2009, 81, 5218-5225) that employed for target detection a simple biophysical mechanism of target antibody induced annealing between two complementary oligonucleotides attached to the antigen peptide. In this work, we propose and experimentally validate an alternative variant of this assay format in which target antibody binding to antigen peptide-oligonucleotide conjugate produces a complex with high sequence-specific binding affinity to a single-stranded capture oligonucleotide. This new assay format can be used for preparing various solid-surface based assays by immobilizing the capture oligonucleotide. This assay design is not limited to antibody detection. We demonstrate that it can also be employed for detecting proteins or pathogenic bacteria using oligonucleotide-labeled antibodies as target recognition elements. Preparation of these solid-surface based assays is simplified because all interactions with the solid surfaces are mediated by well-understood oligonucleotide-oligonucleotide interactions and because of the relative ease of immobilizing oligonucleotides on various solid surfaces. These unique aspects of the assay design also allow microarray-style multiplexing that could be most useful for multiplexed antibody profiling for diagnosis and analysis of cancer, autoimmune, and infectious diseases.     

Thermal Properties and Wetting Behavior of High Temperature Zn-Al-In Solders

Solders for ultrahigh-temperature applications were defined by Vianco as those able to sustain working conditions with temperatures as high as 573 K, with momentary temperature rise up to 623 K. Zn-Al eutectic alloy (12 at.% Al) fits such defined criteria with respect to its melting temperature. It was found that small additions of indium to Zn-Al eutectic lower its melting temperature. The aim of this work is to assess if and to what extent thermal properties and wetting behavior are affected. It was found that addition of In increases electrical resistivity and coefficient of thermal expansion value. Wetting angles on Cu and Al substrates of liquid Zn-Al eutectic-based alloys containing up to 1.5 at.% of In were studied with the sessile drop method, after wetting at 773 K in the presence of flux. A decrease of apparent wetting angle was observed with increasing concentration of In. After wetting tests solidified alloy-substrate couples were cross-sectioned and examined with scanning electron microscopy coupled with electron dispersive X-ray analysis.     

ND++ – an extended IPv6 Neighbor Discovery protocol for enhanced stateless address autoconfiguration in MANETs

Recent trends in information and communications technologies are oriented toward the design of the Future Internet and the Internet of Things. While IPv6‐based mobile ad hoc networks (MANETs) are emerging as an important building block of these new technologies, it is necessary to come up with adequate self‐configuration capabilities allowing for seamless and automated configuration of addresses in mobile environment. The mechanisms of stateless address autoconfiguration proposed for IPv6 networks are supposed to automate some configuration steps; however, they would need to be aligned with the requirements imposed by MANET networks. Therefore, in this article, we present Neighbor Discovery ++ – an extended IPv6 Neighbor Discovery protocol for enhanced duplicate address detection in MANETs, which provides increased coverage of network nodes, while minimizing protocol overhead. It exploits efficient flooding mechanism on the basis of the multipoint relay concept, which makes it an interesting approach also for large‐scale networks. Trials performed on the designated real‐world testbed platform indicate that ND++ is a promising solution to support efficient address autoconfiguration in MANETs. Copyright © 2012 John Wiley & Sons, Ltd.     

Unusual Solidification Behavior of the Suction-Cast Cu-Zr-Al-Y Alloy Doped with Fe

The effect of iron addition on the microstructure of the Cu-Zr-Al-Y glass-forming alloy was studied. Despite a high superficial cooling rate, small Fe additions (1.5 and 3 pct) induced formation of crystalline CuZr and AlCu₂Zr phases on the outer layers of suction-cast rods. As the melt composition near the solid/liquid interface was depleted in Fe, the remaining melt vitrified at a relatively low cooling rate.     

Variational modelling of wave–structure interactions with an offshore wind-turbine mast

We consider the development of a mathematical model of water waves interacting with the mast of an offshore wind turbine. A variational approach is used for which the starting point is an action functional describing a dual system comprising a potential-flow fluid, a solid structure modelled with nonlinear elasticity, and the coupling between them. We develop a linearized model of the fluid–structure or wave–mast coupling, which is a linearization of the variational principle for the fully coupled nonlinear model. Our numerical results for the linear case indicate that our variational approach yields a stable numerical discretization of a fully coupled model of water waves and an elastic beam. The energy exchange between the subsystems is seen to be in balance, yielding a total energy that shows only small and bounded oscillations amplitude of which tends to zero with the second-order convergence as the timestep approaches zero. Similar second-order convergence is observed for spatial mesh refinement. The linearized model so far developed can be extended to a nonlinear regime.     

Curing and Morphology Studies of Thermosets from Blends of a Main Chain Liquid Crystalline Polyester and Diepoxide/Diamine

Summary: Blends of the commercial liquid‐crystalline polyester Rodrun LC‐3000 (60–90 wt.‐%) with a bisphenol A‐diglycidyl ether based diepoxide (DOW D.E.R.330) and an aromatic diamine (MCDEA) prepared in a twin‐screw extruder have been compression‐moulded and cured either isothermally at 260 °C or in a temperature ramp between 160 and 230 °C. The blends were investigated with SEM and thermal analysis (DSC, DMTA). Blends with 80% Rodrun and less cured at 260 °C and the blend containing 60% Rodrun cured in a temperature ramp showed macro‐phase separation followed by reaction‐induced micro‐phase separation (RIPS) both in the Rodrun‐rich and in the epoxy‐rich macro‐separated phases. Blends containing 90, 80 and 70% Rodrun moulded at 160 °C and cured in the temperature ramp showed only RIPS and a morphology rather similar to that of the uncured blends that was most likely co‐continuous; the blend with 90% Rodrun cured at 260 °C showed RIPS and a dispersed epoxy phase in a Rodrun matrix. Phase composition has been determined by extraction of the soluble fraction and chemical analysis.

SEM showing the reaction induced micro‐phase separation for sample REA90/10i.     

Solvent induced morphologies of poly(methyl methacrylate-b-ethylene oxide-b-methyl methacrylate) triblock copolymers synthesized by atom transfer radical polymerization

Poly(methyl methacrylate-b-ethylene oxide-b-methyl methacrylate) (PMMA-PEO-PMMA) triblock copolymers were synthesized using atom transfer radical polymerization (ATRP) and halogen exchange ATRP. PEO-based macroinitiators with molecular weight from M_n = 2000 to 35,800 g/mol were used to initiate the polymerization of MMA to obtain copolymers with molecular weight up to M_n = 82,000 g/mol and polydispersity index (PDI) less than 1.2. The macroinitiators and copolymers were characterized by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. The melting temperature and glass transition temperature of the copolymers were measured by differential scanning calorimetry (DSC). Crystallinities of the PEO blocks were determined from the WAXS patterns of both homopolymers and block copolymers, which revealed the fragmentation of PEO blocks due to the folding of the PMMA chains. Interestingly, the fragmentation was less pronounced when cast on surfaces compared to that in bulk, as measured by GISAXS. Solvent casting was used to control the morphology of the copolymers, permitting the formation of various states including amorphous, induced micellar with a PMMA core and flower-like PEO arms, and a cross-linked gel. Atomic force microscopy (AFM) was used to visualize the different copolymer morphologies, showing micellar and amorphous states.     

Speciation and ecological risk of toxic elements in estuarine sediments affected by multiple anthropogenic contributions (Guadiana saltmarshes, SW Iberian Peninsula): I. Surficial sediments

Recent studies have demonstrated that the Guadiana Estuary contains metal concentrations in excess of background values. Therefore, this work aims to document the potential environmental hazards associated with the availability of these metals in this environment of high ecological value. Mineralogical analysis shows that the sediments are composed mainly of quartz, albite, and clay minerals (illite, smectite, kaolinite, and vermiculite) along with several small, reactive compounds (including soluble sulphated salts, Fe-Mn oxyhydroxides, organic matter, and pyrite) capable of retaining metals, which can be subsequently released, causing environmental degradation. BCR sequential extraction shows that As, Cd, Cu, Mn, Pb, and Zn present mobile fractions with respect to the total metal content (41, 100, 57, 53, 70, and 69%, respectively) in any of the described reactive phases (F1 + F2 + F3).Calculated environmental risk indices demonstrate moderate to considerable ecological risk for almost the entire estuary, associated mainly with acid mine drainage from the nearby Iberian Pyrite Belt. In addition, the indices highlight several zones of extremely high risk, which are related to industrial and urban dumps in the vicinity of the estuary and to heavy traffic on the international bridge.