Production and Bioactivity of Common Lichen Metabolites as Exemplified by <Emphasis Type="Italic">Heterodea muelleri</Emphasis> (Hampe) Nyl.

Based on results of a former study in 2005, this investigation aimed at quantifying UV- and cold temperature stress-induced changes within the secondary metabolite production of the cultured mycobiont of the lichen Heterodea muelleri (Hampe) Nyl. The chemical profiles of the mycobiont cultures and the lichen thallus were determined by high-performance liquid chromatography (HPLC) and thin layer chromatography (TLC) analyses. The voucher specimen of H. muelleri produced diffractaic acid as a major polyketide and barbatic acid as a satellite compound, whereas the untreated mycobiont did not contain any detectable secondary metabolites. While UV-C stress caused a general increase in substance formation, cold temperature stress resulted in a strong activation of barbatic acid biosynthesis. A further series of experiments focused on the effect of diffractaic and barbatic acids on the growth of the symbiotic photobiont Trebouxia jamesii; usnic acid was similarly tested. Pure substances were obtained from mycobiont cultures by performing preparative TLC. A determined quantity of algae was incubated on BBM plates that contained three different concentrations of the pure lichen metabolites. The growth of the photobionts was monitored over a period of 1 mo to evaluate the impact of each substance on the cultured algae. While diffractaic and usnic acid had no noticeable effect, barbatic acid strongly inhibited algal growth and resulted in cell death.     

Effect of annealing time and addition of lactose on release of a model substance from Eudragit RS coated pellets produced by a fluidized bed coater

The aim of this study was to investigate the effects of annealing time and addition of lactose in coating liquid formulations on the release of a model substance, methylene blue (MB), from pellets coated with Eudragit^® RS 30 D. The microcrystalline cellulose pellets were layered with MB before coating with aqueous dispersions of Eudragit^® RS 30 D using a Wurster-type fluidized bed coater. The coating processes and conditions were validated and optimized before the final coating. The uncoated and coated pellets were characterized for their size, MB content, morphology and MB release. The results demonstrated that a stable coating process can be developed to produce repeatable batches of pellets. The film thickness was calculated and found to be similar to those observed from scanning electron microscope. The increased annealing time led to a more coherent film. The drug release was found to vary depending on the duration of annealing time and the addition of lactose. Addition of lactose gave a faster MB release and without any initial lag period in the release profile whereas the increased annealing time slowed down the MB release and increased the lag period.     

Polyethylene {201} crystal surface: interface stresses and thermodynamics

We describe a method to determine the mechanical and thermodynamic properties of the interface between a polyethylene crystal and melt by united-atom Monte Carlo simulations. In particular, the {201} fold surface is studied in the temperature range 380-450 K. The interface properties are defined by using the concept of a sharp Gibbs dividing surface, which in turn is used to define the interface internal energy and the interface stresses. We find that the internal energy of the interface is of the order 0.3-0.35 J/m². The interface stresses are anisotropic for the {201} crystal surface with values of approximately −0.27 and −0.4 J/m² for the xx- and yy-components, respectively. By way of the Herring equation, the surface tension of the fold surface is independent of shear strains in the interface. The temperature and strain derivatives of the interface properties are also measured and discussed in detail. The influence of the interface internal energy and of phase change contributions on the macroscopic heat capacity of the semi-crystalline material is examined.     

Electrosynthesis of trimethylorthoformate on BDD electrodes

The anodic methoxylation of formaldehyde dimethylacetal (FADMA) to trimethylorthoformate (TMOF) in basic methanol was investigated on boron-doped diamond (BDD) electrodes. Cyclic voltammetry and preparative electrolysis have shown that FADMA is electrochemically inactive in the solvent stability region; nevertheless FADMA can be oxidized in the potential region of methanol oxidation. A reaction scheme involving intermediates of methanol oxidation (methoxy radicals) has been proposed.     

EUV‐Lithographie für zukünftige IC‐Chips. EUV‐Lithography for Future IC‐Technology

In the past the overwhelming success of the semiconductor industry was based on the realisation of ever smaller structures on chips in ever shorter periods. This allowed to increase the computational speed of the processors and the amount of data that can be stored in a memory chip. This reduction of the critical dimension was mastered within optical lithography by transition to smaller wavelengths. Those lithography technologies that are currently in the development or test phase, based on 193 nm or as well 157 nm laser sources, will not achieve dimensions around 50 nm. A fundamental change of technology is thus emerging. The currently favored basis for dimensions of 50 nm and below is EUV lithography, based on an optical technology with an exposure wavelength of 13,4 nm. This substantial reduction of the wavelength also implies a radical change of the methodology used up to now.     

Software-Agenten im Semantic Web

Zusammenfassung Die Entwickler des Semantic Web orientieren sich in ihrem Verst?ndnis von Software-Agenten an der Konzeption der Agentenkommunikationssprache ACL von DARPA. Dabei werden Agenten aufgrund ihrer F?higkeit, korrekt in ACL zu kommunizieren, definiert.     

7-Chloro-4-nitrobenzofurazan inactivates chloroplast H(2+)-ATPase by modification of different tyrosines, depending on the presence of ATP

The addition of 7-chloro-4-nitrobenzofurazan (NBD) to isolated CF1 at pH 7.5 leads to one tyrosine-bound NBD molecule per CF1 in one of the three beta-subunits, concomitantly with the inhibition of the ATPase activity. Addition of ADP prior to NBD-incubation protected the ATPase activity and reduced binding of NBD to beta-subunits. The addition of MgATP prior to modification did not result in protection against modification of the beta-subunit as well as preservation of activity. Cleavage of the NBD-labelled subunits with cyanogen bromide, followed by analysis of the labelled peptides, led to detection of a 14C-labelled peptide of 7 kDa in both cases (+/- ATP-preincubation). Sequence analysis of this peptide showed that in ATP-incubated CF1, tyr beta 328 was modified with NBD-Cl, whereas the ATP free sample contained no NBD bound to this tyrosine. Further digestion of the labelled peptide with protease V8 (Staphylococcus aureus) followed by sequence analysis of the radioactive labelled peptide, led to the detection of beta-tyr362 as the modified amino acid in case of ATP-free CF1. Both tyrosines are closely related to a proposed nucleotide binding region of beta.     

Power-to-gas in a smart city context – Influence of network restrictions and possible solutions using on-site storage and model predictive controls

Power-to-gas (P2G or PtG) technology can provide energy storage capacity to the energy system by converting excess electrical energy into hydrogen and feeding it into the natural gas network, where it can be stored. However nowadays hydrogen feed-in has to be limited to certain percentages in order to keep the characteristics of the resulting gas mixture (i.e. heating value) within the national standards. For P2G plants in urban areas this can strongly impact the economic viability. This paper investigates the use of on-site storage and model predictive controller (MPC) to ease the negative effect of restrictions in the gas and power grid on the economics of P2G systems. Three different use-cases for P2G in an urban setting are considered: Optimal utilisation of renewable electricity produced within the boundaries of the city, optimised electricity purchase at the spot market and optimal usage of electric network. MPC is compared to an optimised rule-based control approach. Results show that both controls can be used to meet the objectives and operate the power-to-gas plant. However, the MPC approach results in a smoother operation of the plant and significantly improved economic performance in all cases and is recommended. The results indicate the beneficial effects of on-site hydrogen storage on system operation and economics. For the investigated cases a storage capacity around 6 full load hours of the electrolyser was sufficient to improve results significantly.