The Role of Biomass in a Future World without Fossil Fuels

The demand, production, supply and use of biomass in a future world after the depletion of fossil fuels is described. In a world without fossils, the limited biomass harvest is the only carbon source. Supply of food and feed has first priority. Demand, supply and use of biomass as the only carbon raw material for the production of a number of indispensable carbon products are analyzed. Bioenergy via combustion plays a significant, but not a decisive role, because the future energy mix is dominated by other renewables. Despite considerable uncertainties of the long‐term assessment, some clear hints for a reasonable further development of biomass technologies can be extracted.     

Self-assembly of functional nanostructures from ABC triblock copolymers

The spontaneous formation of nanostructured materials by molecular self-assembly of block copolymers is an active area of research, driven both by its inherent beauty and by a wealth of potential technological applications. Thin films of block copolymers have attracted increasing interest, particularly in view of possible applications in nanotechnology. Although much of the work has concentrated on block copolymers consisting of two components, the insertion of a third block greatly enlarges the structural diversity and allows incorporation of additional chemical functionality. Here we describe a highly ordered hexagonally perforated lamella structure based on an ABC triblock copolymer thin film. By suitable choice of the three blocks a versatile structure is formed. The perforated lamella can serve as a lithographic mask, it can be chemically converted into an amphiphilic structure without losing its order, and after selective removal of one of its constituents it could be used as a responsive membrane. Intriguingly, the particular choice of the blocks ensures that the structure is formed irrespective of the chemical nature of the solid substrate. The experimental results are supported by mesoscale computer simulations.     

Density of desublimed layers

Starting from the assumption that the growth of desublimed layers is governed mainly by heat and mass transfer, the authors present a model based on conditions in the diffusion boundary layer and suggest that the “hoarfrost”

1 Hereafter the term frost will be used instead of hoarfrost.

density depends on only one parameter. The discussion accounts for the process determining factors, i.e. the growth rate, mass transfer and gas concentration. The theoretical relationship is confirmed by the authors' own experiments on two systems and data from literature. The relationship can be established by a few laboratory experiments and permits the calculation of frost density and of associated variables, thus facilitating the optimization of desublimator design.     

Gadolinium-enhanced magnetic resonance angiography of abdominal blood vessels

Contrast enhanced (CE) magnetic resonance angiography (MRA) provides high resolution angiograms within 20-40 sec. The technique is based on the acquisition of heavily T1-weighted three-dimensional (3D) gradient-echo data sets (FISP) with ultrashort echo-(< 2ms) and repetition times (< 5 ms) during arterial phase of an intravenously injected bolus of a T1-shortening agent such as Gd-DTPA. For MR-angiography of abdominal vessels CE-MRA is better suited than "time-of flight" (TOF) and phase-contrast (PC) MRA because motional artifacts can be obviated with breath-held acquisitions. We have optimised the technique and evaluated its potential for angiography of the abdominal aorta and its branches as well as the portal vein and its tributaries. Whilst CE-MRA provides reliable diagnostic accuracy in the aorta and the proximal sections of its branches, small peripheral arteries cannot be assessed accurately. The portal vein and its tributaries can often be depicted better with CE-MRA than with conventional angiography but, like conventional angiography, CE-MRA is hampered by slow and reversed flow, conditions under which TOF or "true FISP" MRA may perform bst. We have also investigated FLASH-echo-planar imaging (EPI) hybrid techniques, a further technical development which due to shorter acquisition times of 12-15 sec. allows semi-dynamic imaging of the arterial and venous phase and provide better vessel contrast due to the use of fat-suppression.     

Manufacturing Surface Hardened Components of 42CrMo4 by Water‐Air Spray Cooling

By employing integrated heat‐treatment using forging heat, a significant shortening of the process chain is attained for manufacturing precision forged components with considerable savings in time and energy. With the aid of water‐air spray cooling, surface hardening and tempering can be carried out without, at the same time, reheating the component following quenching. In this work, geometric models of splines and single cylinder crankshafts (both made of 1.7225) were surface hardened and tempered using a purpose‐built rotating spray unit. The obtained hardness, microstructures and their distortions were investigated. To optically and spatially detect the components, fringe and shadow projection systems were employed. In a second research topic, the influence of the spray parameters on the component's distortion was investigated. For both components; the splined shaft and the crankshaft geometries, it was possible to carry out successful surface heat‐treatments using these processes.     

In Situ Reconstruction of Helical Iron Borophosphate Precatalyst toward Durable Industrial Alkaline Water Electrolysis and Selective Oxidation of Alcohols

Iron-based (pre)catalysts have attracted enormous attention for various electrooxidation reactions due to the low cost, high abundance, and multiple accessible redox states of iron. Herein, a well-defined helical iron borophosphate (LiFeBPO) is developed as an electro(pre)catalyst for the oxygen evolution reaction (OER) and selective alcohol oxidation. When deposited on nickel foam (NF), LiFeBPO exhibits an exceptional OER performance at ambient conditions attaining a current density of 100 mA cm⁻² at ≈276 mV overpotential in 1 m KOH. Notably, this anode sustains durable alkaline water electrolysis at 500 mA cm⁻² for over 330 h under industrial conditions (6 m KOH and 85 °C). In –situ and ex situ investigations reveal a deep reconstruction of LiFeBPO during OER, which transforms into a 3D open porous skeleton assembled by ultrasmall, low-crystalline α-FeOOH nanoparticles (interfacing with NiOOH of NF). This structure contributes to exposing accessible surface active sites, as well as accelerating mass transport and bubble detachment. Moreover, this electrode also catalyzes the electrooxidation of alcohols (methanol, ethylene glycol, and glycerol) to formic acid (FA) with high selectivity and full conversion. This study provides promising solutions for designing suitable anodes for the simultaneous production of green hydrogen fuel and value–added FA from electrooxidation reactions.     

Zum Einfluss von in Flüssigkeiten unter Druck gelösten Gasen auf Grenzflächenspannungen und Benetzungseigenschaften

Measurements of interfacial tensions of water and ethanol in dense carbon dioxide up to 10 MPa and 373 K were performed. Also, in order to predict the wettability of these liquids on teflon and glass surfaces in the presence of carbon dioxide, contact angles between these liquids and both surfaces were determined under the same conditions of pressure and temperature. The interfacial tension were measured according to the pendant drop method. A mathematical derivation for the evaluation of the interfacial tension according to the geometry of the pendant drop and the difference of the density between the phases is presented. The contact angle determinations were performed using both the static and the dynamic method. The results show that because of the solubility of carbon dioxide in the liquids, the measured interfacial tensions are much lower than the interfacial tension of the pure substances. The interfacial tension appears as a function of only the density of CO₂ above its critical temperature [1]. Even though the solubility of carbon dioxide in the liquid phase affects the interfacial tension, such a clear relation between these variables, like the one between the interfacial tension and the density of carbon dioxide, cannot be observed. The excess concentration on the interphase, as a measurement of adsorption according to Gibbs, was calculated for both systems. The contact angle of water on teflon surface increases with pressure until total non wetting is reached. On the other hand, the contact angle of ethanol decreases with the increasing pressure until spreading occurs. The same phenomena was noted for the wetting characteristic of water on glass surface. The contact angle of water increases as pressure increases. Ethanol spreads totally on the surface of glass at all evaluated pressures. With the dynamic method, contact anglesgreater than the ones obtained with the static method were measured.