The use of a dynamic hydrogen electrode as an electrochemical tool to evaluate plasma activated carbon as electrocatalyst support for direct methanol fuel cell

The objectives of this study were to functionalize the carbon black surface by chemically introducing oxygenated groups using plasma technology. This should enable a better interaction of the carbon support with the metallic catalyst nanoparticles, hindering posterior support particle agglomeration and preventing loss of active surface. PtRu/C nanoparticles were anchored on the carbon supports by the impregnation method and direct reduction with hydrazine. Physical characterization of the materials was carried out using energy dispersive X-ray analysis and transmission electron microscopy. The screen printing technique was used to produce membrane electrode assemblies for single cell tests in methanol/air (DMFC). Tests were carried out using the dynamic hydrogen electrode as an electrochemical tool to evaluate the anode and cathode behavior separately.     

Identification of organically farmed Atlantic salmon by analysis of stable isotopes and fatty acids

Using isotope ratio mass spectrometry (IRMS), the ratios of carbon (δ ¹³C) and nitrogen (δ ¹⁵N) stable isotopes were investigated in raw fillets of differently grown Atlantic salmon (Salmo salar) in order to develop a method for the identification of organically farmed salmon. IRMS allowed to distinguish organically farmed salmon (OS) from wild salmon (WS), with δ ¹⁵N-values being higher in OS, but not from conventionally farmed salmon (CS). The gas chromatographic analysis of fatty acids differentiated WS from CS by stearic acid as well as WS from CS and OS by either linoleic acid or α-linolenic acid, but not OS from CS. The combined data were subjected to analysis using an artificial neural network (ANN). The ANN yielded several combinations of input data that allowed to assign all 100 samples from Ireland and Norway correctly to the three different classes. Although the complete assignment could already be achieved using fatty acid data only, it appeared to be more robust with a combination of fatty acid and IRMS data, i.e. with two independent analytical methods. This is also favourable with respect to a possible manipulation using suitable feed components. A good differentiation was established even without an ANN by the δ ¹⁵N-value and the content of linoleic acid. The general applicability in the context of consumer protection should be checked with further samples, particularly regarding the variability of feed composition and possible changes in smoked salmon.     

Simulation of a reversible SOFC with Aspen Plus

A thermodynamic Aspen Plus simulation model for a reversible solid oxide fuel cell (RSOFC) is presented and evaluated. It is composed of an electrolysis and a fuel cell module. The latter is based on an existing non reversible SOFC model. The electrolysis model simulates water electrolysis as well as catalytic reactions of inlet gases. The model has been validated using data from literature. It has been found that the support layer on fuel electrode supported cells has to be treated differently in terms of diffusion than the active layer. Simulation results show that for the investigated cell parameters, the positive effect of adding CO₂ to the steam feed on the electrolysis process is due to water–gas-shift reactions and not CO₂ electrolysis. An analysis of outlet gas compositions in electrolysis mode showed that the assumption of the cell as an equilibrium reactor was justified. A parameter study has been conducted, showing that increasing the operation temperature and pressure can improve the overall performance, while changing the inlet gas compositions in general improves either fuel cell or electrolysis mode and deteriorates performance for the other mode.     

Absicherung von Zulaufreaktoren durch Überwachung der Reaktantenakkumulation mittels On-line-Energiebilanzierung

Safe Operation of Semi-Batch Reactors by Supervising the Accumulation of Reactants Through Online Energy Balance . An essential part of the strategy for ensuring safe operating conditions for semi-batch reactors is the permanent guarantee of an admissible accumulation of reactants. Thus, even in case of a failure or a breakdown of the cooling system or the agitator, the maximum possible pressure and temperature in the reactor still remain within their permissible limits. The energy balance method makes it possible to monitor online the reactant concentration and to limit the accumulation by switching off the feed of reactant in time. Practical experience with a production plant is presented in which, over a period of 2 years, numerous process cycles were calculated and subjected to comparative analysis. The results show that the reproducibility as well as the accuracy of calculation are high and that the energy balance method can be regarded as reliable. In addition, recommendations for the implementation of this safety strategy as a reliable tool in plants are obtained. On this basis, the energy balance method provides additional information about the process and, thus, can provide an increase of plant safety and product quality by maintaining process availability.     

Influence of Some Trace Elements on Solidification Path and Microstructure of Al-Si Foundry Alloys

In the present study, Ca, Ni, V, and Zn were added to a high purity binary Al-7wt pct Si and commercial purity A356 foundry alloy in the nominal range of 50 to 600 ppm in order to study their effect on the solidification path and the resultant microstructure. Thermal analysis was used to assess nucleation and growth of the various phases. It was found that Ca and Ni additions suppress characteristic temperatures associated with nucleation and growth of the eutectic by up to 4 and 1.5 K, respectively. Additionally, Ca was observed to modify the eutectic Si and a concentration as low as 39 ppm Ca was sufficient to precipitate the geometrically unfavored polyhedral Al₂Si₂Ca phase. Furthermore, Ni addition resulted in the formation of two intermetallic phases when the Ni concentration exceeded 300 ppm. These phases have been quantified as Al₃Ni and Al₉FeNi by SEM-EDS. V and Zn had no apparent effect on the cooling curve and the microstructure. Even though it could be shown that V accumulates preferably in β-Al₅FeSi particles, V concentrations of 600 ppm were too low to have any influence on the phase’s morphology.     

BaTiO3–P(VDF-HFP) nanocomposite dielectrics—Influence of surface modification and dispersion additives

We report on BaTiO₃–polymer composites as dielectrics for film capacitors. BaTiO₃ was synthesized by a sol–gel soft-chemistry method leading to spherical nanoparticles with a high degree of surface hydroxyl groups which turned out to be important for the bonding of surfactant molecules. As surfactants, n-octylphosphonic acid and 2,3,4,5,6-pentafluorobenzyl phosphonic acid were used to inhibit particle agglomeration and to improve the wetting behaviour with the polymer. The phosphonic acid-coated BaTiO₃ nanoparticles were dispersed in solutions of poly(vinylidefluoride-co-hexafluoropropylene). Composite films were prepared by the spin-coating technique. A systematic study was performed on the influence of varying oxide fractions, different surfactants and the effect of additional dispersion aids such as sodium dodecyl sulphate or BYK-W 9010 on the quality and dielectric properties of the films obtained. The chemical adjustment of the 2,3,4,5,6-pentaflourobenzyl phosphonic acid within the fluorinated organic host form a more uniform particle distribution and increase relative permittivity of the resulting composite material compared to the unflourinated surfactant. Additionally, an enhancement of the relative permittivity can be realized by adding of dispersants. These two components can increase the relative permittivity by factor 5 compared to the pure polymer material.     

Spatio-Temporal Data Types: An Approach to Modeling and Querying Moving Objects in Databases

Spatio-temporal databases deal with geometries changing over time. In general, geometries cannot only change in discrete steps, but continuously, and we are talking about moving objects. If only the position in space of an object is relevant, then moving point is a basic abstraction; if also the extent is of interest, then the moving region abstraction captures moving as well as growing or shrinking regions. We propose a new line of research where moving points and moving regions are viewed as 3-D (2-D space+time) or higher-dimensional entities whose structure and behavior is captured by modeling them as abstract data types. Such types can be integrated as base (attribute) data types into relational, object-oriented, or other DBMS data models; they can be implemented as data blades, cartridges, etc. for extensible DBMSs. We expect these spatio-temporal data types to play a similarly fundamental role for spatio-temporal databases as spatial data types have played for spatial databases. The paper explains the approach and discusses several fundamental issues and questions related to it that need to be clarified before delving into specific designs of spatio- temporal algebras.     

High refractive index hyperbranched polymers with different naphthalene contents prepared through thiol-yne click reaction using di-substituted asymmetric bulky alkynes

In the present study, different aromatic moieties, naphthalene and benzene, were introduced into alkynes to constitute 1,3,5-tris(naphthylethynyl)benzene as B₃ monomer. This monomer could be reacted with different ratios of hexane-1,6-dithiol (A₂ monomer) via mono-selective Thiol-Yne reaction (TYR) to form hyperbranched polymers PI. TYR yielded in both, model reactions and polymerizations, mono-adducts with high regioselectivity and proved the absence of any bis-adducts. Polymers of very high molecular weights of up to 625,000 g/mol could be achieved without any sign of gel formation. All the polymers exhibit high transparency in the visible wavelength range and also show high refractive indices of up to 1.745 at 589.7 nm due to the high incorporation of naphthalene and phenyl groups. Besides, all polymers prove excellent solubility and processability together with excellent thermal properties.     

Economic Value of Tree Fruit Production in Jordan Valley from a Virtual Water Perspective

The continuous high demand of water resources for agricultural uses in Jordan is leading to a water crisis. A possible partial solution may be to import food which requires large amounts of water to grow instead of cultivating high water consuming crops. Crops such as banana and citrus cause a huge virtual water loss, which can be reduced by cultivating other less water-demanding crops. This paper focuses on analyzing the economic value of cultivating tree fruit from a virtual water perspective. The virtual water calculations in this study depend on the average rainfall, water quota, and the crops’ water requirements (CWR). The gross profit to the water use ratio showed that banana has the lowest value 0.085 JD/m³, while lemon has the highest value 1.65 JD/m³. The calculations show that the average embedded water in fruits varies from about 470 m³/ton for grapes to about 2,500 m³/ton for dates. Banana and citrus plantations consume about 21 and 71 million cubic meters (MCM) annually, respectively, which represent about 85% of the total water consumption in fruit tree plantation. The virtual water flow estimation embedded in fruits shows that Jordan imports about 77 MCM per year. However it exports about 29 MCM per year. The results were analyzed from an integrated water resources management (IWRM) perspective. The analysis shows that a way to recover some of the water costs involved in, e.g., banana production would be to increase the fertilizer cost by about 10%. This would double the water cost and increase the banana production cost by about 6.8%. Using this alternative could be a way to better manage the huge losses in virtual water involved in banana production in the Jordan Valley.