NaWuReT-Workshop: Forschung in der Reaktionstechnik für und mit der Gesellschaft

In this article, the results of the NaWuReT (Early Career Reaction Engineers) workshop on the topic “Are we doing relevant science?” are presented. The topics “(In)surmountable hurdles for Citizen Scientists in reaction engineering?” and “Circular Economy in reaction engineering with/for society?” were discussed. Therefrom, a variety of ideas and suggestions were extracted.     

Evaluation of a Novel Plasmid for Simultaneous Gene Electrotransfer-Mediated Silencing of CD105 and CD146 in Combination with Irradiation

Targeting tumor vasculature through specific endothelial cell markers represents a promising approach for cancer treatment. Here our aim was to construct an antibiotic resistance gene-free plasmid encoding shRNAs to simultaneously target two endothelial cell markers, CD105 and CD146, and to test its functionality and therapeutic potential in vitro when delivered by gene electrotransfer (GET) and combined with irradiation (IR). Functionality of the plasmid was evaluated by determining the silencing of the targeted genes using qRT-PCR. Antiproliferative and antiangiogenic effects were determined by the cytotoxicity assay tube formation assay and wound healing assay in murine endothelial cells 2H-11. The functionality of the plasmid construct was also evaluated in malignant melanoma tumor cell line B16F10. Additionally, potential activation of immune response was measured by induction of DNA sensor STING and proinflammatory cytokines by qRT-PCR in endothelial cells 2H-11. We demonstrated that the plasmid construction was successful and can efficiently silence the expression of the two targeted genes. As a consequence of silencing, reduced migration rate and angiogenic potential was confirmed in 2H-11 endothelial cells. Furthermore, induction of DNA sensor STING and proinflammatory cytokines were determined, which could add to the therapeutic effectiveness when used in vivo. To conclude, we successfully constructed a novel plasmid DNA with two shRNAs, which holds a great promise for further in vivo testing.     

Depassivation and repassivation of stainless steels by stepwise pH change

Immersion tests with different stainless steels have been performed, while the pH was stepwise decreased and then increased again. During 8.5-day exposure, the depassivation and repassivation pH values as a function of pitting resistance equivalent number were determined. There is always a gap between both pH values (depassivation and repassivation), indicating that for every steel, there are conditions where an existing passive layer can be maintained but cannot be rebuilt after depassivation. In such environments, the passive layer is thicker, consisting mainly of molybdenum and iron rich oxides, while chromium is dissolved. Usually, depending on conditions, the passive layer is more chromium-rich, especially the inner layer. This is relevant, for example, for acidizing jobs in oil and gas industry, proving that repassivation after acidizing will happen promptly, when the pH is increased again.     

Young Scientists – Juniorprofessor Gregor D. Wehinger stellt sich vor

This article introduces assistant professor Gregor D. Wehinger of the Institute of Chemical and Electrochemical Process Engineering at Clausthal University of Technology. Besides recent research projects and teaching activities, he gives an overview about his commitment to the community. He reports on current research results in the field of CFD modeling of packed-bed reactors, redox-flow batteries, and multiphase systems. Furthermore, the use of virtual reality in teaching is presented.     

Mechanische Hochtemperatureigenschaften von flugaschebasierten Geopolymerbetonen

Mechanical properties of fly ash‐based geopolymer concretes at high temperature At present, concretes based on alkali‐activated binders, so‐called geopolymer concretes, are investigated intensively in the building materials industry and by the research community as environmentally friendly alternative to Portland cement‐based concretes. These inorganic binders, which are based on industrial by‐products such as fly ash and ground granulated blast furnace slag, exhibit high resistance against corrosive acids and salts, if properly designed. The mechanical properties of fly ash‐based geopolymer concretes at high temperatures are subject of systematic investigations at the Bundesanstalt für Materialforschung und ‐prüfung (BAM) to create a basis for the structural design of fire exposed concrete members based on alkali‐activated binders. The concrete specimens, produced with quartz aggregates or lightweight aggregates and heated to a maximum temperature of 750 °C, exhibited a decrease of compressive strength up to temperatures of ca. 300 °C, attributed to formation of microcracks caused by dehydration. At higher temperatures the compressive strength of the investigated geopolymer concretes recovered partly, due to sintering processes starting from ca. 500 °C. Because of this beneficial property when compared to conventional concretes, geopolymer concretes can potentially be applied in infrastructure facilities where fire resistance is critical. From the results of the thermomechanical tests stress‐strain relationships are derived that can be used for the structural design of members made from geopolymer concretes.     

Photobleaching Reveals Heterogeneous Stoichiometry for Equinatoxin II Oligomers

Equinatoxin II (EqtII), a sea anemone cytolysin, is known to oligomerize to form pores that spontaneously insert into membranes. Crystallographic and cryo‐EM studies of structurally similar cytolysins offer contradictory evidence for pore stoichiometry. Here we used single‐molecule photobleaching of fluorescently labeled EqtII to determine the stoichiometry of EqtII oligomers in supported lipid bilayers. A frequency analysis of photobleaching steps revealed a log‐normal distribution of stoichiometries with a mean of 3.4±2.3 standard deviations. Comparison of our experimental data with simulations of fixed stoichiometries supports our observation of a heterogeneous distribution of EqtII oligomerization. These data are consistent with a model of EqtII stoichiometry where pores are on average tetrameric, but with large variation in the number of subunits in individual pores.     

Arsenic removal during conventional aluminium-based drinking-water treatment

The changing forms and concentrations of arsenic through aluminium-based coagulation treatment processes were tracked for three drinking-water treatment plants. This has provided direct evidence of where and how arsenic is removed. In general, soluble As(V) is converted to particulate As(V) by adsorption during rapid mixing, and is removed along with naturally occurring particulate arsenic predominantly by clarification. Soluble As(III) tracks through the treatment processes and is converted to soluble As(V) during final chlorination. The ability of a water treatment process to achieve the maximum acceptable concentration for arsenic in drinking water is dependent on the concentration of As(III) in the source water.