DFC++ Processing Framework Concept

Development of modern Software Defined Radio (SDR) based communication systems can be accelerated significantly by the use of processing frameworks. The evolution of SDR and the involved departure from digital representations of classical radio architecture towards more abstract software systems raises new requirements of increased flexibility and versatility. The proposed Data Flow Control for C++ (DFC++) processing framework concept addresses those requirements by employing modern programming techniques and flow control mechanisms to allow for variable data rates, dynamic paths, and flexible component designs. Another important trend is the integration of various embedded platforms in the software radio domain. The rapidly increasing performance and efficiency of embedded processors enables the deployment of SDR systems in more space and power constrained environments. Therefore covering a heterogeneous hardware selection becomes increasingly important for processing frameworks. By relying exclusively on C++ and minimizing external dependencies, DFC++ is specifically aiming for excellent portability and adaptability to support a wide range of current and future software radio projects while maintaining high performance and ease of use. This paper introduces the key aspects of the DFC++ concept and implementation with focus on the reference pointer based data transport mechanisms responsible for the propagation of user data between different processing components.     

Channel model for satellite indoor communication,system design

In this paper the development of a channel model for wireless indoor communication, specifically with regard to indoor retransmission of satellite signals and reception by fixed and portable receivers in the L band, is described. The study is confined to the channel model, though it does not include the assessment of particular transmission forms. The theories and approaches used in the model are mainly derived from the field of mobile communication. They are combined to a straightforward chain from large- to small-scale variations yielding information about the several stages of fading. One of the features is the evaluation of the complex field distribution across a local area that can be transformed into a time-varying fading when assuming a moving receiver or a non-stationary environment. © 1998 John Wiley & Sons, Ltd.     

Metabolomic profiling of beer reveals effect of temperature on non-volatile small molecules during short-term storage

The effect of temperature on non-volatile compounds in beer has not been well characterised during storage. Here, a metabolomics approach was applied to characterise the effect of storage temperature on non-volatile metabolite variation after 16weeks of storage, using fresh beer as a control. The metabolite profile of room temperature stored (RT) and cold temperature stored (CT) beer differed significantly from fresh, with the most substantial variation observed between RT and fresh beer. Metabolites that changed during storage included prenylated flavonoids, purines, and peptides, and all showed reduced quantitative variation under the CT storage conditions. Corresponding sensory panel observations indicated significant beer oxidation after 12 and 16weeks of storage, with higher values reported for RT samples. These data support that temperature affected beer oxidation during short-term storage, and reveal 5-methylthioadenosine (5-MTA) as a candidate non-volatile metabolite marker for beer oxidation and staling.     

Mechanism of osmotic activation of the quaternary ammonium compound transporter (QacT) of Lactobacillus plantarum

The accumulation of quaternary ammonium compounds in Lactobacillus plantarum is mediated via a single transport system with a high affinity for glycine betaine (apparent Km of 18 microM) and carnitine and a low affinity for proline (apparent Km of 950 microM) and other analogues. Mutants defective in the uptake of glycine betaine were generated by UV irradiation and selected on the basis of resistance to dehydroproline (DHP), a toxic proline analogue. Three independent DHP-resistant mutants showed reduced glycine betaine uptake rates and accumulation levels but behaved similarly to the wild type in terms of direct activation of uptake by high-osmolality conditions. Kinetic analysis of glycine betaine uptake and efflux in the wild-type and mutant cells is consistent with one uptake system for quaternary ammonium compounds in L. plantarum and a separate system(s) for their excretion. The mechanism of osmotic activation of the quaternary ammonium compound transport system (QacT) was studied. It was observed that the uptake rates were inhibited by the presence of internal substrate. Upon raising of the medium osmolality, the QacT system was rapidly activated (increase in maximal velocity) through a diminished inhibition by trans substrate as well as an effect that is independent of intracellular substrate. We also studied the effects of the cationic amphipath chlorpromazine, which inserts into the cytoplasmic membrane and thereby influences the uptake and efflux of glycine betaine. The results provide further evidence for the notion that the rapid efflux of glycine betaine upon osmotic downshock is mediated by a channel protein that is responding to membrane stretch or tension. The activation of QacT upon osmotic upshock seems to be brought about by a turgor-related parameter other than membrane stretch or tension.     

XPS study of the influence of temperature on ZnDTP tribofilm composition

Antiwear additives, such as zinc dialkyldithiophosphate (ZnDTP), find application in many different industrial sectors. Although it is understood that certain ZnDTP concentrations need to be used to achieve an effective antiwear performance, there has been very little work published concerning the effect of temperature on the interactions of the additive and its adsorption mechanism on steel. In this article, 100Cr6 (52100) steel ball-on-disc experiments under solutions of zinc dialkyldithiophosphate (ZnDTP) in poly-α-olefin (PAO) were performed at different temperatures, ranging from 25 to 180 °C. The discs were analysed after the experiments by means of small-area, imaging and angle-resolved X-ray photoelectron spectroscopy (XPS). The composition of the reaction film was found to change as a function of the applied temperature and also to vary within the film as a function of depth: Longer polyphosphate chains were found at higher temperatures as well as towards the outer part of the reaction film.     

Functional Coatings on High‐Performance Polymer Fibers for Smart Sensing

Above a critical temperature, high‐performance fibers may lose their mechanical properties resulting in catastrophic events of damage when, e.g., used as load‐carrying ropes. Here, a method to functionalize polymer fibers with thermochromic optical coatings that enable signaling of damaging thermal history is introduced. These smart coatings are comprised of an index‐tunable anti‐reflection coating based on chalcogenide phase change materials (PCM). It is demonstrated that the insulator?metal phase transition of these materials can be aligned with the critical deterioration temperature of both polyethylene terephthalate (PET) monofilaments and liquid‐crystal polyester (LCP) yarns by composition tuning. The carefully designed optical system amplifies the change in optical properties of its constituents upon phase change. The thermal and mechanical degradation of these fibers can thus be monitored and displayed by eye.     

Characterization and distribution of mechanically competent mineralized tissue in micropores of β-tricalcium phosphate bone substitutes

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Biofunctional Polyelectrolyte Multilayers and Microcapsules: Control of Non‐Specific and Bio‐Specific Protein Adsorption

Layers of the polyelectrolytes poly(allylamine hydrochloride) (PAH, polycationic) and poly(styrene sulfonate) (PSS, polyanionic) are consecutively adsorbed on flat silicon oxide surfaces, forming stable, ultrathin multilayer films. Subsequently, a final monolayer of the polycationic copolymer poly(L ‐lysine)‐graft‐poly(ethylene glycol) (PLL‐g‐PEG) is adsorbed onto the PSS‐terminated multilayer in order to impart protein resistance to the surface. The growth of each of the polyelectrolyte layers and the protein resistance of the resulting [PAH/PPS]_n(PLL‐g‐PEG) multilayer (n = 1–4) are followed quantitatively ex situ using X‐ray photoelectron spectroscopy and in situ using real‐time optical‐waveguide lightmode spectroscopy. In a second approach, the same type of [PAH/PSS]_n(PLL‐g‐PEG) multilayer coatings are successfully formed on the surface of colloidal particles in order to produce surface‐functionalized, hollow microcapsules after dissolution of the core materials (melamine formaldehyde (MF) and poly(lactic acid) (PLA; colloid diameters: 1.2–20 μm). Microelectrophoresis and confocal laser scanning microscopy are used to study multilayer formation on the colloids and protein resistance of the final capsule. The quality of the PLL‐g‐PEG layer on the microcapsules depends on both the type of core material and the dissolution protocols used. The greatest protein resistance is achieved using PLA cores and coating the polyelectrolyte microcapsules with PLL‐g‐PEG after dissolution of the cores. Protein adsorption from full serum on [PAH/PPS]_n(PLL‐g‐PEG) multilayers (on both flat substrates and microcapsules) decreases by three orders of magnitude in comparison to the standard [PAH/PPS]_n layer. Finally, biofunctional capsules of the type [PAH/PPS]_n(PLL‐g‐PEG/PEG‐biotin) (top copolymer layer with a fraction of the PEG chains end‐functionalized with biotin) are produced which allow for specific recognition and immobilization of controlled amounts of streptavidin at the surface of the capsules. Biofunctional multilayer films and capsules are believed to have a potential for future applications as novel platforms for biotechnological applications such as biosensors and carriers for targeted drug delivery.