The adsorption properties of PdZnx alloy on Pd(1 0 0): Preparation and characterization

The formation of PdZn_x alloy on Pd(1 0 0) and its characteristics were investigated by various methods, such as photoelectron, auger-electron, electron energy loss, thermal desorption spectroscopic methods and work-function measurement. The alloy was produced by the decomposition of diethyl zinc on Pd(1 0 0). The alloy surface reacts with O₂ and ZnO_x is formed. The reactivity of alloy to hydrogen is similar to that of K/Pd. The stability of adsorbed CO is lower than on clean Pd(1 0 0).     

Corrosion protection with zinc-rich epoxy paint coatings embedded with various amounts of highly dispersed polypyrrole-deposited alumina monohydrate particles

Active anodic zinc content below 90 wt.% does not support sufficient electrical contacts but higher contents cause high porosity of traditional liquid zinc-rich paints (ZRPs). To resolve this problem, our proposal is the application of highly dispersed polypyrrole (PPy) coated alumina inhibitor particles (PCAIPs) in zinc-rich paint compositions. Using these nano-size inhibitor particles at concentrations from 4.55 to 0.85 wt.%, hybrid paints were formulated with zinc contents ranging from 60 to 85 wt.% at the same time. Submicron morphology and nano-scale structure, spectroscopy characteristics and electrochemical properties of the PCAIPs were studied by transmission electron microscopy (TEM) and rheology, Fourier-transform infrared spectroscopy (FT-IR) and cyclic voltammetry (CV) in first part of the work. In the second part, electrolytic corrosion resistivity of two sets of paint coatings were salt-spray chamber and immersion tested with 5 wt.% aqueous solution of sodium chloride. Active corrosion prevention ability of the salt-spray tested coatings was evaluated in compliance with ISO recommendations. Dielectric properties of the coatings during the immersion tests were monitored by electrochemical impedance spectroscopy (EIS). Corrosion tested area of the coatings was investigated by glow-discharge optical emission spectroscopy (GD-OES) to disclose infiltration of corrosive analytes and oxygen enrichment in the cross-section of the primers in comparison with their pristine states. Morphology of the zinc pigments was examined by scanning electron microscopy (SEM), and quality of steel specimens and the interfacial binder residues by X-ray photoelectron spectroscopy (XPS) as well as FT-Raman and Mössbauer spectroscopy. The results of both types of corrosion tests evidenced efficient utilisation of sacrificial anodic current for galvanic protection and improved barrier profile of the hybrid coatings, along with the PCAIP inhibited moderate self-corrosion of zinc. As a result of well balanced active/passive function, the hybrid coating containing zinc at 80 wt.% and PCAIPs at 1.75 wt.% embedding PPy at 0.056 wt.% indicated the most advanced corrosion prevention. Galvanic function of the hybrid paints is interpreted on the basis of size-range effect and spatial distribution of the alumina supported PPy inhibitor particles and basic electrical percolation model considerations.     

Quasi-superactivation of classical capacity of zero-capacity quantum channels

One of the most surprising recent results in quantum Shannon theory is the superactivation of the quantum capacity of a quantum channel. This phenomenon has its roots in the extreme violation of additivity of the channel capacity and enables reliable transmission of quantum information over zero-capacity quantum channels. In this work we demonstrate a similar effect for the classical capacity of a quantum channel which previously was thought to be impossible. We show that a nonzero classical capacity can be achieved for all zero-capacity quantum channels and it only requires the assistance of an elementary photon–atom interaction process – stimulated emission.     

Surface modification of multi-wall carbon nanotubes by nitrogen attachment

Commercial multiwall carbon nanotubes (MWCNT-s) were treated by RF activated N₂ gas plasma at (nominally) room temperature. Treatment time of 5 to 10 min was applied at negative bias varying in the 0-300 V range. Surface chemical alterations were followed by X-ray photoelectron spectroscopy (XPS). All the applied treatments resulted in a significant build-up of nitrogen in the surface of MWCNT-s. The amount of nitrogen varied between 19 and 25 at.% depending on the treatment time and, in a lesser extent, also on biasing conditions. Interestingly, the nitrogen attachment was also significant (20 at.%) when the treatment commenced without bias. Evaluating the high-resolution N1s XP spectral region, typically three different chemical bonding states of the nitrogen was delineated. Peak component at 398.3 ± 0.3 eV is assigned to CNC type, at 399.7 ± 0.3 eV to sp² N in melamine-type ring structure and at 400.9 ± 0.3 eV to N substituting carbon in a graphite-like environment. Identical chemical bonding of the nitrogen was detected on the surface of highly oriented pyrolytic graphite (HOPG) and on microcrystalline graphite surfaces treated in the same way for comparison. Estimating the penetration depth of the nitrogen atoms by the SRIM program it was concluded that at the applied DC bias energy range the implanted nitrogen is incorporated in the top 2-4 monoatomic layers of the samples. A model for the distribution of the chemically bonded nitrogen on the outer walls of the MWCNT-s is proposed.     

Stabilisation of SWNTs by alkyl-sulfate chitosan derivatives of different molecular weight: towards the preparation of hybrids with anticoagulant properties

We have previously demonstrated that chitosan derivative N-octyl-O-sulfate chitosan (NOSC), which presents important pharmacological properties, can suspend single walled carbon nanotubes (SWNTs) up to 20 times more effectively than other chitosan derivatives in an aqueous environment. In an attempt to further investigate the impact of different molecular weights of chitosan to the solubilization and anticoagulant properties of these hybrids an array of NOSC derivatives varying their molecular weight (low, medium and high respectively) was synthesised and characterised by means of FT-IR spectroscopy, NMR spectroscopy and thermal gravimetric analysis (TGA). Microwave and nitric acid purified SWNTs, characterised by FT-IR spectroscopy, transmission electron microscopy (TEM) and Raman spectroscopy, were colloidally stabilised by these polymers and their anticoagulant activity was assessed. The results revealed that the low molecular weight NOSC coated SWNTs exhibit the highest activity when 0.5 mg mL(-1) NOSC solutions are used, activity which is similar to that of the free polymer. Preliminary studies by exposure of these hybrids to Brine Shrimp (Artemia) cysts revealed no effect on the viability of sub-adult Artemia. Our findings suggest the possibility of tailoring these nanomaterials to bear the required properties for application as biocompatible building blocks for nanodevices including biosensors and biomaterials.     

Influence of the type and degree of alteration of andesite and dacite on the quality and life of asphaltic concrete

This report deals with the influence of alteration processes in andesite and dacite with special reference to those alterations and characteristics of stone having the greatest influence on the quality of asphaltic concrete mixes. Using andesites and dacites with extremely different properties for standard asphaltic mixes has proved that quality of the mixes very much depends on the quality of the stone aggregate used. Properties of stone aggregate of different degree and type of alteration have a significant influence on the rheological characteristics of bitumen. Therefore, special attention has been paid to this influence.     

Simultaneous measurements of individual ambient particle size, composition, effective density, and hygroscopicity

The interaction between atmospheric particles and water vapor impacts directly and significantly the effect that these particles exert on the atmosphere. The hygroscopicity of individual particles, which is a quantitative measure of their response to changes in relative humidity, is related to their internal compositions. To properly include atmospheric aerosols in any model requires knowledge of the relationship between particle size, composition, and hygroscopicity. Here we demonstrate the capability to conduct in real time the simultaneous measurements of individual ambient particle hygroscopic growth factors, densities, and compositions using a humidified tandem differential mobility analyzer that is coupled to an ultrasensitive single-particle mass spectrometer. We use as an example the class of particles that are composed of sulfate mixed with oxygenated organics to illustrate how multidimensional single-particle characterization can be extended to yield in addition quantitative information about the composition of individual particles. We show that the data provide the relative concentrations of organics and sulfates, the density of the two fractions, and particle hygroscopicity.     

Roh-, verdauliche und unverdauliche Fruchtk?rperproteine in AusternseitlingenPleurotus ostreatus (Pilze)

Zusammenfassung Verschiedene Eiweißtypen (Roheiweiß, verdauliches und unverdauliches Eiweiß) wurden in Hüten und Stielen vonPleurotus ostreatus (Austernseitling) in vier Reifephasen analysiert. Diese Reifephasen waren: A (Durchmesser der Hüte <5 cm); B (D: 5–8 cm); C (D: 8–10 cm) und D (Durchmesser >10 cm). Die untersuchtePleurotus-Sorte (der Hüte und Stiele) hat einen relativ hohen Rohproteingehalt, zu 92% (durchschnittlich) verdaulich ist. Höhere Roh- und verdauliche Eiweißgehalte wurden in der zweiten Phase (B) gefunden. Die höheren Angaben des unverdaulichen Eiweißes wurden in den Fruchtkörpern der letzten Phase gemessen. Diese Angaben können auch die Pilzanbauer für die Optimalisierung der Pilzproduktion- und Ernte gut verwenden.

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Crude, digestible and non-digestible proteins in fruit bodies ofPleurotus ostreatus (oyster mushroom)

Different kinds of protein (crude, digestible, non-digestible) were analysed in caps and stipe ofPleurotus ostreatus (oyster mushroom) in four phases of development. The phases examined were: A (cap diameter <5 cm); B (diameter 5–8 cm); C (diameter, 8–10 cm) and D (diameter >10 cm). ThePleurotus variety analysed (the cap and the stipe) has a relative high crude protein content, the main part of which is digestible (average, 92%). During the four stages of fruit body ripening, stage B was the best, with the highest crude and digestible protein concentrations. In stage D the highest nondigestible protein content was measured in the cap and stipe. These data can be used for optimal harvesting of fruit bodies of cultivatedP. ostreatus.

     

CFD as a tool in risk assessment of inhaled radon progenies

During the last decade, computational fluid dynamics techniques proved to be a powerful tool in the modelling of biological processes and the design of biomedical devices. In this work, a computational fluid dynamics method was applied to model the transport of inhaled air and radioactive particles within the human respiratory tract. A finite volume numerical approach was used to compute the flow field characteristics and particle trajectories in the lumen of the first five airway generations of the human tracheobronchial tree, leading to the right upper lobe. The computations were performed for breathing and exposure conditions characteristic of uranium mines and homes. Primary radon daughter deposition patterns and energy distributions were computed, exhibiting highly inhomogeneous particle and energy deposition patterns. The results of the present modelling effort can serve as input data in lung cancer risk analysis.