New applications of the borrowing hydrogen methodology - selective synthesis of amines and mechanistic studies

This cumulative thesis deals with the application of the Borrowing Hydrogen methodology in organic synthesis. During my research, the Borrowing Hydrogen methodology was applied in the synthesis of secondary and tertiary amines starting from secondary alcohols by C-O activation. Furthermore, I was able to introduce the selective synthesis of monoalkylated aryl amines using aliphatic amines by C-N activation. This new method was continuously applied in the alkylation of t-alkyl amines. Additionally, mechanistic studies in the activation and deactivation of the Shvo catalyst were performed

Contribution of Enzyme Catalysis to the Achievement of the United Nations’ Sustainable Development Goals

In September 2015, the United Nations General Assembly established the 2030 Agenda for Sustainable Development, which includes 17 Sustainable Development Goals (SDGs). The interlinked SDGs are intended to be a ‘shared blueprint for peace and prosperity for people and the planet, now and in the future’ (https://sdgs.un.org/SDGs, accessed on 28 April 2023). The agenda emphasizes a holistic approach to achieving sustainable development for all, balancing the economic, social, and environmental dimensions of sustainable development. The agenda recognizes that ending poverty and other forms of deprivation must align with strategies that improve health and education, reduce inequality, and promote economic growth—all while tackling climate change and working to preserve our oceans and forests. Implementing the SDGs will require collaboration between different actors in government, industry, and civil society, as well as scientists from different disciplines. In the scientific community, the SDGs should provide a framework and serve as the guiding principles for research activity. Enzyme catalysis, among many other disciplines, can could represent a valuable contribution to the SDGs. The aim of this editorial chapter is to highlight the potential of enzyme catalysis in achieving the SDGs and to contribute to the realization of a ‘better world’, while reflecting on the deployment of these technologies to achieve these goals

Fundamentals and Design Model for Verification of Timber Components with High Performance Fire Resistance Coatings

Die Musterbauordnung erlaubt den Einsatz von Holzkonstruktionen bis einschließlich der Gebäudeklasse 4. Die tragende und aussteifende Holzkonstruktion muss dazu jedoch durch eine brandschutztechnisch wirksame Bekleidung aus nichtbrennbaren Baustoffen gekapselt werden. Ein neuer Ansatz zur Vermeidung einer Entzündung im Brandfall ist der Einsatz einer Hochleistungsbrandschutzbeschichtung, die als deckender oder transparenter Anstrich auf die Holzbauteile aufgetragen wird. Unter Temperatureinwirkung bildet sie eine voluminöse Schicht, die das Holz isoliert und seine Entzündung hinauszögert. Der Entzündungsschutz durch industriell gefertigte Produkte kann nach derzeitigem Stand der Forschung über mehr als 30 Minuten Normbrandbeanspruchung wirksam sein. Mit der Hochleistungsbrandschutzbeschichtung lassen sich die gleichen Schutzziele wie mit einer Bekleidung zuverlässig erreichen, obwohl die Beschichtung selbst ein brennbarer Baustoff ist. Der planende Ingenieur benötigt ein Bemessungswerkzeug, mit dem die Wirkung der Beschichtung auf den Entzündungsschutz und auf die Tragfähigkeit brandbeanspruchter Holzbauteile quantifiziert werden kann. Hierfür wird ein deterministisches Ingenieurmodell entwickelt. Dieses wird durch ein semiprobabilistisches Sicherheitskonzept ergänzt, um die Einhaltung der gleichen Zuverlässigkeit wie bei Bauteilen mit Bekleidung nachweisen zu können. Das Modell wird anhand von Brandversuchen und Simulationsrechnungen überprüft und kalibriert. Parameterstudien haben gezeigt, dass sich die Tragfähigkeit von Balken und Stützen bei 30-minütiger Normbrandbeanspruchung durch die Beschichtung deutlich steigern lässt. Schlanke Holzstützen, die allein eine Feuerwiderstandsdauer von 30 Minuten nicht erreichen, können in Verbindung mit einer transparenten Beschichtung für einen Entzündungsschutz von weniger als 30 Minuten in die Feuerwiderstandsklasse R 30 eingestuft werden.The German model building code allows timber constructions up to ”Class IV” with five storey buildings. In this case the load bearing and stiffening components have to be encapsulated by a non-flammable cladding to prevent their ignition when a fire occurs. A relatively new approach to avoid the ignition in case of a fire is the use of High Performance Fire Resistance Coatings (HPFRC) which are applied on timber components such as ordinary opaque or transparent paints. Under exposure to high temperatures it forms into a voluminous foam which insulates the wood and prevents ignition or at least delays it for some time. According to the state-of-the-art in science and research the ignition protection can be effective for more than 30 minutes under standard (ISO) fire exposure. In this work it is shown that HPFRC can reach the same fire safety objectives as non-flammable claddings although the coating itself is a flammable material. The designing engineer needs a tool to quantify the protective effect of the coating both in terms of preventing ignition as well as the load bearing capacity of timber members during the fire process. For this reason, a deterministic design model was developed which is supplemented by a probabilistic safety concept to ensure the generally accepted safety levels in a quantitative manner. The developed model has been calibrated with various fire tests and simulations. On the basis of the design model, extensive parameter studies were performed. They have shown that load bearing capacity of beams and columns can be significantly improved for a standard (ISO) fire of 30 minutes. Slender columns that cannot reach a fire resistance rating of 30 minutes without any cladding or coating can be improved to European class R 30 rating using a transparent HPFRC which prevents ignition for less than 30 minutes

Criticial Assessment of the Photocatalytic Reduction of Cr(VI) over Au/TiO2

The purification of drinking water is one of the most urgent challenges in developing countries, for which the efficient removal of traces of heavy metals, e.g., Cr(IV), represents a key technology. This can be achieved via photocatalysis. In this study, we compare the performance of Au/TiO2 to bare TiO2 P25 catalysts. Furthermore, the influence of the sacrificial reagent citric acid under UV-Vis and Vis excitation was investigated and a detailed investigation of the catalysts before and after reaction was performed. During the photocatalytic reduction of Cr(IV) under acidic conditions, both leaching of Au, as well as absorption of Cr, occur, resulting in new catalyst systems obtained in situ

Optical control of AMPA receptors using a photoswitchable quinoxaline-2,3-dione antagonist

AMPA receptors respond to the neurotransmitter glutamate and play a critical role in excitatory neurotransmission. They have been implicated in several psychiatric disorders and have rich pharmacology. Antagonists of AMPA receptors have been explored as drugs and one has even reached the clinic. We now introduce a freely diffusible photoswitchable antagonist that is selective for AMPA receptors and endows them with light-sensitivity. Our photoswitch, ShuBQX-3, is active in its dark-adapted trans-isoform but is significantly less active as its cis-isoform. ShuBQX-3 exhibits a remarkable red-shifting of its photoswitching properties through interactions with the AMPA receptor ligand binding site. Since it can be used to control action potential firing with light, it could emerge as a powerful tool for studying synaptic transmission with high spatial and temporal precision

Строительство воздушной линии 10 кВ ПС «Новокормиловка» – ПС «Восход»

Цель дипломной работы – проектирование ВЛ 10кВ для повышения надежности электроснабжения ПС Восход.В процессе работы выполнены электрические расчёты для выбора провода воздушной линии электропередачи. Выполнен расчет токов короткого замыкания и на его основе произведен выбор отключающих аппаратов, установленных на опорах ВЛ в начале и в конце линии электропередачи.The purpose of the thesis is designing a 10 kV overhead line to improve the reliability of power supply to the Voskhod substation.In the process of work, electrical calculations have been made to select the wire of the overhead power transmission lineThe calculation of short-circuit currents is made and on its basis a selection of switching devices installed on the OHL supports at the beginning and at the end of the transmission line was made

Nickel as a co-catalyst for photocatalytic hydrogen evolution on graphitic-carbon nitride (sg-CN): what is the nature of the active species?

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The nature of a nickel-based co-catalyst deposited on a sol-gel prepared porous graphitic-carbon nitride (sg-CN), for photocatalytic H-2 production from water, has been investigated. The formation of the active catalytic species, charge separation and recombination of the photogenerated electrons and holes during photochemical H-2 evolution has been determined for the first time using in situ EPR spectroscopy.DFG, EXC 314, Unifying Concepts in CatalysisBMBF, 03IS2071D, Light2Hydroge

Intraoperative fluid restriction in pancreatic surgery : a double blinded randomised controlled trial

Background : Perioperative fluid restriction in a variety of operations has shown improvement of: complications, recovery of gastrointestinal function and length of stay (LOS). We investigated effects of crystalloid fluid restriction in pancreatic surgery. Our hypothesis: enhanced recovery of gastrointestinal function. Methods : In this double-blinded randomized trial, patients scheduled to undergo pancreatoduodenectomy (PD) were randomized: standard (S: 10ml/kg/hr) or restricted (R:5ml/kg/hr) fluid protocols. Primary endpoint: gastric emptying scintigraphically assessed on postoperative day 7. Results : In 66 randomized patients, complications and 6-year survival were analyzed. 54 patients were analyzed in intention to treat: 24 S-group and 30 R-group. 32 patients actually underwent a PD and 16 patients had a palliative gastrojejunostomy bypass operation in the full protocol analysis. The median gastric emptying time (T1/2) was 104 minutes (S-group, 95% confidence interval: 74-369) versus 159 minutes (R-group, 95% confidence interval: 61-204) (P = 0.893, NS). Delayed gastric emptying occurred in 10 patients in the S-group and in 13 patients in the R-group (45% and 50%, P = 0.779, NS). The primary outcome parameter, gastric emptying time, did not show a statistically significant difference between groups. Conclusion : A fluid regimen of 10ml/kg/hr or 5ml/kg/hr during pancreatic surgery did not lead to statistically significant differences in gastric emptying. A larger study would be needed to draw definite conclusions about fluid restriction in pancreatic surgery

Asymmetric azidohydroxylation of styrene derivatives mediated by a biomimetic styrene monooxygenase enzymatic cascade

Enantioenriched azido alcohols are precursors for valuable chiral aziridines and 1,2-amino alcohols, however their chiral substituted analogues are difficult to access. We established a cascade for the asymmetric azidohydroxylation of styrene derivatives leading to chiral substituted 1,2-azido alcohols via enzymatic asymmetric epoxidation, followed by regioselective azidolysis, affording the azido alcohols with up to two contiguous stereogenic centers. A newly isolated two-component flavoprotein styrene monooxygenase StyA proved to be highly selective for epoxidation with a nicotinamide coenzyme biomimetic as a practical reductant. Coupled with azide as a nucleophile for regioselective ring opening, this chemo-enzymatic cascade produced highly enantioenriched aromatic α-azido alcohols with up to >99% conversion. A bi-enzymatic counterpart with halohydrin dehalogenase-catalyzed azidolysis afforded the alternative β-azido alcohol isomers with up to 94% diastereomeric excess. We anticipate our biocatalytic cascade to be a starting point for more practical production of these chiral compounds with two-component flavoprotein monooxygenases. A one-pot enzymatic cascade for the asymmetric azidohydroxylation of styrenes leads to chiral 1,2-azido alcohols with up to two stereocenters

Optical control of NMDA-receptors with a diffusible photoswitch

N-methyl-D-aspartate receptors (NMDARs) play a central role in synaptic plasticity, learning and memory, and are implicated in various neuronal disorders. We synthesized a diffusible photochromic glutamate analogue, azobenzene-triazole-glutamate (ATG), which is specific for NMDARs and functions as a photoswitchable agonist. ATG is inactive in its dark-adapted trans-isoform, but can be converted into its active cis-isoform using one-photon (near UV) or two-photon (740 nm) excitation. Irradiation with violet light photo-inactivates ATG within milliseconds, allowing agonist removal on the timescale of NMDAR deactivation. ATG is compatible with Ca2+ imaging and can be used to optically mimic synaptic coincidence detection protocols. Thus, ATG can be used like traditional caged glutamate compounds, but with the added advantages of NMDAR specificity, low antagonism of GABAR-mediated currents, and precise temporal control of agonist delivery