Hydrogen peroxide and chlorine detection is critical for many biological and environmental applications. Hydrogen peroxide plays important roles in a variety of fields including plant physiology, medical, environmental and biochemical applications. Its role in plant defense and signal transduction, diseases such as Parkinson's and Alzhemier's, industrial processes such as disinfection and wastewater treatment and biochemical enzymatic reactions is critical. Given the gamut of areas that hydrogen peroxide is a key component of; its detection assumes great importance. Similarly chlorine has long been used as a disinfectant for making drinking water safe, but excessive chlorination is an environmental and health hazard in itself. In this work, micromachining techniques have been used to design, fabricate and test electrochemical sensors and microneedle structure that can be integrated for detection of hydrogen peroxide and free chlorine. A novel nanomaterial has been integrated with the hydrogen peroxide microsensor, which greatly increases the sensor lifetime and robustness. Miniaturization, low detection limits, high sensitivity and selectivity, as well as ease of fabrication are some of the other advantages of this work.

Aufgrund ihrer Fähigkeit, sich an wechselnde Umgebungsdrücke anzupassen, ist die Aerospikedüse eines von mehreren Düsenkonzepten, welches die Effizienz von weitgehend technologisch ausgereiften chemischen Raumfahrtantrieben weiter steigern kann. Darüber hinaus kann die Höhenadaptivität der Düsenart eine wichtige Voraussetzung für Landungsszenarien oder Probenrückführungsmissionen auf Planeten und Monden mit dichter Atmosphäre sein. Um den technologischen Reifegrad der Aerospikedüse zu erhöhen, wurde im Rahmen dieser Arbeit ein additiv gefertigtes Aerospikedemonstratortriebwerk entwickelt und getestet. Als Treibstoffe kommen Kerosin und der als nachhaltig klassifizierte Treibstoff Wasserstoffperoxid zum Einsatz. Beide lagerfähigen Treibstoffe erlauben prinzipiell den Einsatz in Missionsszenarien außerhalb der Erdatmosphäre. In diesem Zusammenhang wird die Auslegung des Demonstrators vorgestellt. Das Triebwerk ist für einen Schub von 6 kN bei einem Brennkammerdruck von 2,0 MPa ausgelegt und wird aus der Nickelbasis-Superlegierung Inconel® 718 im selektiven Laserschmelzverfahren (LPBF) hergestellt. Es wird ein gestuftes Konzept verwendet, bei dem Wasserstoffperoxid durch einen Katalysator zersetzt und die Verbrennung durch Selbstzündung von Kerosin eingeleitet wird. Die Konfiguration der Zersetzungskammer wird als austauschbare Unterbaugruppe konzipiert und besteht aus einem Parallelinjektor, einem Gehäuse und einer Verteilerplatte. Somit können mehrere Katalysatorzusammensetzungen während der experimentellen Validierung getestet werden. Der Kerosininjektor nutzt das Konzept der transversalen Injektion, bei dem der Treibstoff orthogonal zum zersetzten Wasserstoffperoxid eingespritzt wird. Die beiden Hauptkomponenten des Triebwerks, der Zentralkörper Spike und die Brennkammeraußenwand Shroud, werden additiv gefertigt und enthalten Kühlkanäle für ein Wasserkühlsystem. Die Arbeit erläutert neben der Konstruktion Herausforderungen und Lösungsansätze, welche während der Fertigung des Demonstrators aufgetreten sind. Hierbei ist vor allem die konsequente Optimierung des belichteten Querschnitts zu nennen. Abschließend werden die Resultate der experimentellen Demonstratorvalidierung zusammengefasst. Zuerst wurde dazu das Triebwerk nur in Hinblick auf Druckverlust und Dichtigkeit der Kühlung validiert. Anschließend fand eine Heißgastestkampagne im Einstoffbetrieb statt, bei dem der Demonstrator über 2,7 s seine Funktionstüchtigkeit nachweisen konnte. Da signifikante Leckagen festgestellt wurden, musste die Testkampagne anschließend abgebrochen werden, um Reparaturversuche zu unternehmen.

Spermatogenesis is a complex process of male germ cell development from diploid spermatogonia to haploid fertile spermatozoa. Apoptosis plays a vital role in limiting cell numbers and eliminating defective germ cells. This requires novel gene products, and precise and well-coordinated programmes of gene expression. It is therefore possible that a disruption of transcription factor function would significantly impact germ cell development. The present work was undertaken to use Staput separation followed by culture of purified germ cells of rodent testis since mammalian spermatogenesis cannot yet be recreated in vitro. Specificity of separation was assessed using immunocytochemistry to identify spermatogonia, spermatocytes and spermatids. The genotoxins H2O2, doxorubicin, N-ethyl-N-nitrosourea, N-methyl-N-nitrosourea, 6-mercaptopurine, 5-bromodeoxyuridine, methyl methanesulphonate and ethyl methanesulphonate were investigated. Cells were cultured and treated with different concentrations for each agent. DNA damage and apoptosis were measured by Comet and TUNEL assay respectively. Up-regulation of expression of the transcription factors Tbpl1, FHL5 and Gtf2a1l that are important post-meiotically, were examined using RT- PCR and qPCR. Protein production was evaluated using Western blotting. Tbpl1, FHL5 and Gtf2a1l were cloned in-frame into the inducible expression vector pET/100-TOPO. The recombinant clones were induced and successful expression of the proteins in E. coli was confirmed by SDS-PAGE and Western blotting. The recombinant clones obtained were used to demonstrate genotoxin induced impairment of gene expression. Thus, Staput-isolated rodent testicular germ cells seem to be a suitable model to study genotoxicity in vitro yielding result comparable to those reported in vivo. Furthermore, the work shows that genotoxins can impair gene expression.

Hemerythrin-like protein Rv2633c is a small 18 kDa protein that is expressed in Mycobacterium tuberculosis (Mtb). Sequence analysis of Rv2633c predicts the presence of a hemerythrin-like domain, which binds dioxygen using a µ-oxo-bridge (Fe-O-Fe), rather than a heme group. Though it is noticeably upregulated during macrophage infection and during in vitro acidification, the role of Rv2633c in Mtb survival has yet to be elucidated. This project aims to characterize the function of Rv2633c by studying the in vitro response of the recombinant protein to conditions present in the macrophage lysosome, such as reduced oxygen levels or the presence of reactive oxygen species. UV-visible spectroscopy is used to observe these changes, as the spectrum shows a characteristic peak at 330 nm that likely corresponds to the diiron cofactor in its native state. Our results show this spectrum shifts in response to hydrogen peroxide addition, showing the proposed environmental conditions can affect the active site. Bioinformatics techniques, such as the 3D modeling program SWISS-MODEL, have been used to hypothesize possible structure and function. Determining the function of Rv2633c may help explain how Mtb so readily evades the human immune system to reside in the macrophage.

Microplastics are widespread and abundant. Few studies have examined the diversity and abundance of microplastics in wild organisms. This study determined the microplastic quantity and types in the organic tissues of the eastern oyster Crassostrea virginica and Atlantic mud crab Panopeus herbstii from the Indian River Lagoon (IRL). This study also investigated whether location affected the microplastic abundance and variety. Organisms were collected from three sites across Mosquito Lagoon in the northern IRL. Oysters were frozen after collection. Crabs were placed in containers for 5 days before freezing. The soft organic tissue was chemically digested using hydrogen peroxide, filtered, and examined for microplastics. Water samples collected from each study site had an average of 23.1 microplastic pieces per liter and fibers were the most common type. There was a significant interaction for microplastic type and site for both oysters and crabs (p

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