Angiogenic potential of boron-containing bioactive glasses: in vitro study

Boron-containing bioactive glasses (BGs) are being extensively researched for the treatment and regeneration of bone defects because of their osteostimulatory and neovascularization potential. In this study, we report the effects of the ionic dissolution products (IDPs) of different boron-doped, borosilicate, and borate BG scaffolds on mouse bone marrow stromal cells in vitro, using an angiogenesis assay. Five different BG scaffolds of the system SiO₂–Na₂O–K₂O–MgO–CaO–P₂O₅–B₂O₃ (with varying amounts of SiO₂ and B₂O₃) were fabricated by the foam replication technique. Bone marrow stromal cells were cultivated in contact with the IDPs of the boron-containing BG scaffolds at different concentrations for 48 h. The expression and secretion of vascular endothelial growth factor (VEGF) from the cultured cells was measured quantitatively using the VEGF ELISA Kit. Cell viability and cell morphology were determined using WST-8 assay and H&E staining, respectively. The cellular response was found to be dependent on boron content and the B release profile from the glasses corresponded to the positive or negative biological activity of the BGs.     

Produktschonende Betriebs‐ und Designparameter von Wärmeübertragern für temperaturempfindliche Prozessströme

To allow the calculation of product degradation rates as extension to the currently used thermotechnical design calculations for heat exchangers, a volume‐related, reaction‐kinetic approach was developed. Therefore, a model system was selected and the product protection design parameters were determined for a lab‐scale heat exchanger with the help of simulations. The validation was demonstrated in an experiment. Additionally, the product‐protecting operating parameters for the heat exchanger were calculated with a technically relevant set of compounds.     

Security of Water Supply and Electricity Production: Aspects of Integrated Management

The share of renewable resources in electricity generation, e.g. in Germany, is increasing. The power sector is thus becoming more dependent on climate/weather parameters. During the summer months of the last decade, numerous thermal power plants in Europe had to be throttled due to water shortages and high water temperatures. At the same time, Europe was confronted with a reduction in hydropower production. One method of securing a future electricity supply is to increase the reliability of the water supply for power plants. In this paper, scenarios are presented for future electricity production by hydropower and thermal power plants in the Elbe river basin. Electricity production in hydropower plants will decline by approximately 13 % by 2050. This decline is due to climate change and it could be compensated for by optimizing and modernizing existing hydropower plants. Due to higher efficiencies and the conversion of plant cooling systems, no water shortages are expected in most thermal power plants. However, water shortages are expected to affect the plants in the city of Berlin. Inter- and intra-basin water transfers constitute a possible adaptation option. While the transfer of water from the river Oder would be the most cost-efficient solution from Berlin’s perspective, the transfer of water from the river Elbe would have additional positive effects in the upstream Spree river sub-basin.     

2‐(1‐Ethynylpyrene)‐Adenosine as a Folding Probe for RNA—Pyrene in or out

A series of short RNA duplexes containing one or two 1‐ethynylpyrene‐modified adenine bases was synthesised. The melting behaviour of these duplexes was examined by monitoring temperature‐dependent pyrene fluorescence. In the singly modified RNA duplexes, the bases flanking the ethynylpyrene‐rA were varied to examine the sequence specificity of the fluorescence change of pyrene upon RNA hybridisation. Because an increase in pyrene fluorescence upon melting of the duplex can be correlated with intercalation of pyrene, and a decrease is usually associated with the position of pyrene outside the strand, a relationship between the flanking bases and the tendency of the dye to intercalate has been established. It was found that pyrene intercalation is less likely to take place if the modified base is flanked only by A–U base pairs. Flanking G–C base pairs, even only in the 5′‐direction of the modified base, will favour intercalation. In addition, we examined a doubly modified compound that had a pyrene located on each strand. The spectra indicated that the two pyrenes were close enough for interaction. Upon melting of the strand, a fluorescence blue shift corresponding to the dissociation of the pyrene–pyrene complex could be observed in addition to the intensity effect already known from the singly modified compounds. Two melting curves based on the different properties of the fluorophore could be extracted, leading to different melting points corresponding to the global duplex melting and to the change of local pyrene environment, respectively.     

Erstes Design und Einsatz 3D‐gedruckter Strukturen in Blasensäulenreaktoren

A new method is described, in which 3D‐printed structures are implemented in bubble column reactors to dissolve the macroscopic and the microscopic influences. The effect of these structuring method on the fluid dynamic behavior, the gas distribution, mass transfer, and fluid velocity inside bubble columns is shown in this contribution.     

Parameter-study on the influence of steel fibers and coarse aggregate content on the fresh properties of self-compacting concrete

Self-compacting concrete (SCC) offers several economic and technical benefits; the use of steel fibers extends its possibilities. Steel fibers bridge cracks, retard their propagation, and improve several characteristics and properties of the concrete. Fibers are known to significantly affect the workability of concrete. Therefore, an investigation was performed to compare the properties of plain SCC and SCC reinforced with steel fibers. Two mixtures of SCC with different aggregate contents were used as reference. Each of the concretes was tested with four types of steel fibers at different contents in order to answer the question to what extent the workability of SCC is influenced. The slump flow, a fiber funnel and the J-ring test were used to evaluate the material characteristics of the fresh concrete. This paper discusses the suitability of the applied test methods and the effect of the coarse aggregate content, the content and type of steel fibers on the workability of SCC.