The use of new blockcopolymeric dispersing agents for waterborne paints — theoretical and practical aspects

Newly developed blockcopolymeric dispersing agents are evaluated in their performance with a number of pigments in order to obtain a deeper understanding of the dispersing process and of the factors that affect the stability of waterborne binder free pigment concentrates. Special attention is paid to the variation of the amphiphilic ionic/non-ionic and hydrophobic/hydrophilic properties of these new dispersants. By measuring particle surface charges and particle size distributions of pigment pastes and by determining relevant properties of the films obtained after application the effect of a number of binders and other paint components on the stability of dispersions is also evaluated. Guidelines for efficient and economically optimum preparation of pigmented waterborne paints are given.     

In-line measurement of tempered cocoa butter and chocolate by means of near-infrared spectroscopy

In the present work cocoa butter and chocolate were precrystallized by means of a newly developed shear crystallizer. The shear crystallizer was integrated into a circular loop. The handling of precrystallized cocoa butter showed a high dependency on the timing of applied analysis. Differential scanning calorimetry, calorimetry, rheometry, and in-line near-infrared (NIR) were all directly influenced by the fat crystal structure. Nevertheless, for cocoa butter it was shown that mechanical energy input (rpm) had a significant influence on viscosity, melting enthalpy, and slope at the second point of inflection of a temper curve. Experiments with cocoa butter at constant exit temperature showed a linear increase of viscosity between 0.1 and 0.8 Pa·s in the range of 300 to 1300 rpm. Melting enthalpy increased in the same rpm interval from 0.02 to 2.5 J/g. Solidification time (from 4.5 to 0.5 min) and slope (from 0.82 to 0.15, second point of inflection of temper curve) consequently decreased (both with exponential approximation). For cocoa butter, slope and solidification time correlated linearly whereas solidification time and viscosity followed a power law fit. This proved that defined relationships exist between rheological data and data from temper curve measurements. Viscosity was linearly dependent on crystal content. By means of NIR spectroscopy good correlation models for cocoa butter viscosity, enthalpy (crystal content), and slope values were found. For precrystallized chocolate, analytical values such as viscosity and slope values were detected off-line and used for calibration of NIR spectroscopy.     

Characterization of forced oxidation of sardine oil: Physicochemical data and mathematical modeling

It is of major interest to the food industry to understand the mechanisms and kinetics underlying spontaneous oxidation of marine oils because these polyunsaturated fatty acid (PUFA)-rich oils, the object of several health claims, have been repeatedly recommended for dietary intake. The present study attempts to characterize forced oxidation and hydrolytic breakdown of glycerides and fatty acids in sardine oil. A simple, first-order mathematical model was postulated and successfully fitted to the experimental data. This model confirmed that the rate of decrease in concentration of intact fatty acid moieties is almost directly proportional to the number of double bonds present. Therefore, as expected, the rate of oxidative decay was virtually independent of chain length, with an overall activation energy of ca. 22 kJ mol⁻¹. Additionally, the rate of hydrolysis was correlated with the rate of oxidative decay. With the exception of fatty acids possessing more than four double bonds, PUFA proved to be relatively stable to oxidation for up to 10 h at 50–70°C, and the qualitatively richest pattern of volatiles was obtained when the reaction was performed at the highest temperature (80°C).     

Transition metals supported on oxides: density functional cluster studies of palladium deposition on MgO(001)

The interaction of isolated Pd atoms and of a square Pd₄ cluster with the (001) surface of MgO is investigated by means of density functional (DF) calculations. The oxide surface is represented by various model clusters and the effect of the surrounding is taken into account by embedding the cluster in point charges and total ion model potentials. The calculations are performed at the relativistic level using the Becke–Perdew exchange-correlation functional. The adsorption properties determined with this computational scheme are compared with other DF results. The bonding of the Pd atoms and clusters with the surface is analyzed in terms of charge density difference plots. It is found that the polarization of the metal adsorbate due to the surface electric field provides an important contribution to the metal–oxide adhesion energy. This revised version was published online in June 2006 with corrections to the Cover Date.     

Integration of algae-based biofuel production with an oil refinery: Energy and carbon footprint assessment

Biofuel production from algae feedstock has become a topic of interest in the recent decades since algae biomass cultivation is feasible in aquaculture and does therefore not compete with use of arable land. In the present work, hydrothermal liquefaction of both microalgae and macroalgae is evaluated for biofuel production and compared with transesterifying lipids extracted from microalgae as a benchmark process. The focus of the evaluation is on both the energy and carbon footprint performance of the processes. In addition, integration of the processes with an oil refinery has been assessed with regard to heat and material integration. It is shown that there are several potential benefits of co-locating an algae-based biorefinery at an oil refinery site and that the use of macroalgae as feedstock is more beneficial than the use of microalgae from a system energy performance perspective. Macroalgae-based hydrothermal liquefaction achieves the highest system energy efficiency of 38.6%, but has the lowest yield of liquid fuel (22.5 MJ per 100 MJ_algae) with a substantial amount of solid biochar produced (28.0 MJ per 100 MJ_algae). Microalgae-based hydrothermal liquefaction achieves the highest liquid biofuel yield (54.1 MJ per 100 MJ_algae), achieving a system efficiency of 30.6%. Macro-algae-based hydrothermal liquefaction achieves the highest CO₂ reduction potential, leading to savings of 24.5 resp 92 kt CO_2eq/year for the two future energy market scenarios considered, assuming a constant feedstock supply rate of 100 MW algae, generating 184.5, 177.1 and 229.6 GWh_biochar/year, respectively. Heat integration with the oil refinery is only possible to a limited extent for the hydrothermal liquefaction process routes, whereas the lipid extraction process can benefit to a larger extent from heat integration due to the lower temperature level of the process heat demand.     

Targeting Oxidative Stress: Novel Coumarin-Based Inverse Agonists of GPR55

Oxidative stress is associated with different neurological and psychiatric diseases. Therefore, development of new pharmaceuticals targeting oxidative dysregulation might be a promising approach to treat these diseases. The G-protein coupled receptor 55 (GPR55) is broadly expressed in central nervous tissues and cells and is involved in the regulation of inflammatory and oxidative cell homeostasis. We have recently shown that coumarin-based compounds enfold inverse agonistic activities at GPR55 resulting in the inhibition of prostaglandin E₂. However, the antioxidative effects mediated by GPR55 were not evaluated yet. Therefore, we investigated the antioxidative effects of two novel synthesized coumarin-based compounds, KIT C and KIT H, in primary mouse microglial and human neuronal SK-N-SK cells. KIT C and KIT H show antioxidative properties in SK-N-SH cells as well as in primary microglia. In GPR55-knockout SK-N-SH cells, the antioxidative effects are abolished, suggesting a GPR55-dependent antioxidative mechanism. Since inverse agonistic GPR55 activation in the brain seems to be associated with decreased oxidative stress, KIT C and KIT H possibly act as inverse agonists of GPR55 eliciting promising therapeutic options for oxidative stress related diseases.     

Influence of the Metal Particle Size on the Ignition of Energetic Materials

A theoretical study of multi‐particle ignition uses a hot spot model which calculates the temperature evolution of individual hot spots in an energetic material. It indicated that ultra‐fine hot particles would be very effective in igniting energetic materials if impinging and penetrating the solid propellant. Igniting mixtures were prepared containing ultra‐fine Ti particles which react fastest compared with coarse particle mixtures, standard B/KNO₃ and black powder. The ultra‐fine particles, however, are obviously oxidized or gasified too fast as to reach the energetic material to be initiated and longer ignition delays are found mainly compared with coarse particle mixtures. An optimized mixture of coarse and ultra‐fine particles would give an improvement of ignition delay times.     

Development of novel metal-supported proton ceramic electrolyser cell with thin film BZY15–Ni electrode and BZY15 electrolyte

Metal supports for planar MS-PCEC were manufactured using tape-casting of low-cost ferritic stainless steel. A coating protecting the metal support against oxidation was applied by vacuum infiltration and a buffer layer of La_0.5Sr_0.5Ti_0.75Ni_0.25O_3–δ (LSTN) was further deposited to smoothen the surface. The BaZr_0.85Y_0.15O_3–δ–NiO (BZY15–NiO) cathode and the BaZr_0.85Y_0.15O_3–δ (BZY15) electrolyte were applied by pulsed laser deposition (PLD) at elevated substrate temperatures (at 700 °C and 600 °C, respectively). The main challenges are related to the restrictions in sintering temperature and atmosphere induced by the metal support, as well as strict demands on the roughness of substrates used for PLD. Reduction treatment of the half cells confirmed that NiO in the BZY15–NiO layer was reduced to Ni, resulting in increased porosity of the BZY15–Ni cathode, while keeping the columnar and dense microstructure of the BZY15 electrolyte. Initial electrochemical testing with a Pt anode showed a total resistance of 40 Ω·cm² at 600 °C. Through this work important advances in using metal supports and thin films in planar PCEC assemblies have been made.