[en] This paper reports on an empirical investigation about the economic and CO₂ mitigation impacts of bioenergy promotion in the Austrian federal province of Vorarlberg. We study domestic value-added, employment, and fiscal effects by means of a static input-output analysis. The bioenergy systems analysed comprise biomass district heating, pellet heating, and automated wood chip heating systems, as well as logwood stoves and boilers, ceramic stoves, and buffer storage systems. The results indicate that gross economic effects are significant, regarding both investment and operation of the systems, and that the negative economic effects caused by the displacement of conventional decentralised heating systems might be in the order of 20-40%. Finally, CO₂ mitigation effects are substantial, contributing already in 2004 around 35% of the 2010 CO₂ mitigation target of the Land Vorarlberg for all renewable energy sources

[en] Highlights: • Light-weight ferromagnetic Co-Ni-Al:Ti composites were successfully compacted to full density by spark plasma sintering. • During the sintering, new intermetallic phases at Co-Ni-Al/Ti interfaces were formed. • The composites exhibit low density (around 6 g⋅cm^{− 3}), high flexural strength (up to 860 MPa) and detectable ferromagnetic response. • The composites are structurally stable at least from – 120 °C to 400 °C. Light-weight ferromagnetic Co-Ni-Al:Ti composites were consolidated by spark plasma sintering. Powders of ball-milled Co-Ni-Al and gas atomized α-Ti were mixed together in three different ratios and spark plasma sintered at 950 °C, using two sintering times, i.e. dwell times at the maximal temperatures: 1 and 5 min. The composites were successfully compacted and new intermetallic phases were formed at the Co-Ni-Al/Ti interfaces. The composites exhibit favourable flexural strength, excellent high-temperature stability, and relatively high saturation magnetization. On the other hand, the newly emerged intermetallic phases are non-ferromagnetic, which slightly deteriorates the magnetic properties.

[en] Highlights: • Tungsten/P91 steel composites were spark plasma sintered from powder mixtures. • A Fe7W6-like phase was formed between the steel and tungsten grains. • Young's and shear moduli were measured by resonant ultrasound spectroscopy. • FEM was utilized to calculate the effective elastic properties of the individual phases. • Tungsten regions showed low stiffness due to weak bonding of the tungsten grains. - Abstract: Tungsten/steel composites might play an important role in plasma-facing components, especially in joining of tungsten armor to structural parts made of steel. In this work, Young's moduli and shear moduli of a set of tungsten/P91 steel composites fabricated by spark plasma sintering were determined by resonant ultrasound spectroscopy. It was observed that the sintering temperature and the volume fractions of the individual phases have strong effects on the macroscopic elastic constants. The results were interpreted by means of a finite elements numerical model, showing that the regions of imperfectly bonded tungsten particles appearing in the microstructure of some of the composites act effectively as inclusions with very low elastic stiffness. A good correlation between the number of these regions in the microstructure and the elastic constants was observed.

[en] Polyhydroxyalkanoates (PHA) are storage polymers accumulated by numerous prokaryotes in form of intracellular granules. Native PHA granules are formed by amorphous polymer which reveals considerably higher elasticity and flexibility as compared to crystalline pure PHA polymers. The fact that bacteria store PHA in amorphous state has great biological consequences. It is not clear which mechanisms protect amorphous polymer in native granules from transition into thermodynamically favorable crystalline state. Here, we demonstrate that exposition of bacterial cells to particular stressors induces granules aggregation, which is the first but not sufficient condition for PHA crystallization. Crystallization of the polymer occurs only when the stressed bacterial cells are subsequently dried. The fact that both granules aggregation and cell drying must occur to induce crystallization of PHA indicates that both previously suggested hypotheses about mechanisms of stabilization of amorphous state of native PHA are valid and, in fact, both effects participate synergistically. It seems that the amorphous state of the polymer is stabilized kinetically by the low rate of crystallization in limited volume in small PHA granules and, moreover, water present in PHA granules seems to function as plasticizer protecting the polymer from crystallization, as confirmed experimentally for the first time by the present work.

[en] Highlights: • Elastic modulus (E) and shear modulus (G) decrease steadily with the graphene filler content. • The decrease rate for both E and G depends on the exfoliation degree of the graphene filler. • E, G and Poisson coefficient vary with the measurement direction. • Shearability of the composites decreases compared to the monolithic material. - Abstract: Elastic constants of silicon nitride composites with variable content (3–18 wt.%) of two kinds of graphene fillers (nanoplatelets and reduced graphene oxide sheets) are determined using resonant ultrasound spectroscopy. The corresponding Young's modulus (E), shear modulus (G) and Poisson's ratio (ν) are calculated for each material. Composites show a noticeable anisotropy that grows stronger with the graphene filler content, owing to the preferential alignment of the graphene layers and to their own anisotropy as well. E and G monotonically decrease with the filler concentration for both types of fillers, showing a maximum decrease in E of 75% along the direction perpendicular to the graphene plane for the composite with the highest filler content (Si₃N₄–18 wt.% GNP) and a reduction in G of 63% for shear along the graphene plane for the same composite. Influence on the fracture pattern of the composites is also addressed.

[en] Highlights: • Angular dependency of natural convection effects in aluminium finned PCM cavities. • Evaluation of heat transfer enhancement of aluminium proportions and fin spacings. • Guideline values for optimal aluminium proportions in heat transfer structure. • Optimal fin spacing in heat transfer structure for varying cavity orientations. Phase change material (PCM) is applicable in various use cases, such as in a novel hybrid steam/latent heat storage system where containers filled with PCM are placed at the shell surface of a Ruths steam storage (RSS) for retrofitting. The considered approximately rectangular PCM cavity design includes aluminium fins, which is a common choice for heat transfer enhancement. Numerical studies were conducted with two separate numerical models to analyse melting and solidification of PCM in such cavity. Varying aluminium proportions, as well as varying fin spacings were simulated under different orientations of the PCM cavity and their impact on charging/discharging speed was analysed, providing a foundation for design optimization of the considered geometry. Guideline values for optimal aluminium ratio and optimal fin spacing could be obtained. Significant angular dependency on the thermophysical behaviour could be observed during melting, whereas the effect of natural convection during solidification was found to be negligible. The results of this work provide important insight to facilitate the design process of rectangular aluminium finned PCM cavities.