@misc{Maier, type = {Master Thesis}, author = {Maier, Franziska}, title = {Komparative Analyse von Literaturdaten und Herstellerangaben zur Effektivit{\"a}t antimikrobiell ausger{\"u}steter Oberfl{\"a}chen}, school = {Hochschule Rhein-Waal}, abstract = {Die schnelle Ausbreitung von Mikroorganismen wie Bakterien, Pilzen und Viren kann {\"a}ußerst sch{\"a}dlich sein und zu saisonalen Epidemien f{\"u}hren. Dar{\"u}ber hinaus k{\"o}nnen diese Mikroorganismen Lebensmittel und wichtige Materialien verunreinigen, was zu erheblichen wirtschaftlichen Verlusten f{\"u}hrt. Um die Ausbreitung von Mikroorganismen zu verhindern, ist es wichtig, die Wechselwirkungen zwischen verschiedenen Mikroben und Oberfl{\"a}chen zu verstehen, die zu deren Anhaftung und Wachstum f{\"u}hren. Ein solches Verst{\"a}ndnis ist entscheidend f{\"u}r die Entwicklung antimikrobieller Oberfl{\"a}chen. In dieser Arbeit werden verschiedene Ans{\"a}tze und Produkte zu den antimikrobiellen Oberfl{\"a}chen untersucht und Oberfl{\"a}cheneigenschaften mit antimikrobiellen Aktivit{\"a}ten in Beziehung gebracht und analysiert. Eine Gegen{\"u}berstellung der wichtigsten Hersteller von antimikrobiellen Oberfl{\"a}chen und deren Technologien wird durchgef{\"u}hrt und mit aktuellen wissenschaftlichen Studien belegt. Die {\"U}bersicht konzentriert sich auf die physikalische und chemische Modifizierung der Oberfl{\"a}chen, um die Benetzbarkeit, die Oberfl{\"a}chentopografie und die Oberfl{\"a}chenladung zu modulieren und so die Adh{\"a}sion, das Wachstum und die Vermehrung von Mikroben zu hemmen. Dar{\"u}ber hinaus werden die Anwendungsgebiete von antimikrobiellen Oberfl{\"a}chen dargestellt. Die allgemeinen Erwartungen an eine antimikrobielle Oberfl{\"a}che sind hoch, da sie die Anhaftung und das Wachstum von pathogenen Mikroben wirksam verhindern und langlebig sind. Sie sollen sicher f{\"u}r Mensch und Umwelt und m{\"o}glichst kosteng{\"u}nstig sein. Bislang wurde das Design antimikrobieller Oberfl{\"a}chen zumeist nach dem Zufallsprinzip durchgef{\"u}hrt, ohne dass f{\"u}r jede Designstrategie robuste Struktur-Aktivit{\"a}ts-Beziehungen oder die beabsichtigte Verwendung eines bestimmten antimikrobiellen Materials ber{\"u}cksichtigt wurden. Dar{\"u}ber hinaus werden in der vorliegenden Arbeit die wichtigsten Erkenntnisse der Systeme zur Entwicklung antimikrobieller Oberfl{\"a}chen kritisch diskutiert, ebenso wie die Grenzen der aktuellen Forschung und die L{\"u}cke, die noch geschlossen werden muss, bevor diese Ans{\"a}tze in der Praxis umgesetzt werden k{\"o}nnen.}, language = {de} } @masterthesis{Oezkoek, type = {Bachelor Thesis}, author = {{\"O}zk{\"o}k, G{\"u}l}, title = {Molekularbiologische Untersuchungen von Vibrio spp. auf das Vorhandensein von mobilen mcr-Genen und deren Klassifizierung}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:1383-opus4-16148}, school = {Hochschule Rhein-Waal}, pages = {79}, abstract = {Vibrio spp. sind gramnegative Bakterien, die {\"u}berwiegend in aquatischen und marinen Lebensr{\"a}umen vorkommen. Sie umfassen >139 Spezies, von denen 12 Spezies als humanpathogen gelten. Diese unterschiedlichen pathogenen Spezies verursachen verschiedene Erkrankungen und sind vom Tier auf den Menschen {\"u}bertragbar. Durch den Einsatz von Antibiotika steigt die Anzahl resistenter Bakterien rasant an. Im Jahr 2015 wurde erstmals ein Colistin-Resistenz-vermittelndes mcr-1 Gen in einem E. coli identifiziert. Seither wurden r{\"u}ckblickend viele Isolate ermittelt, die mcr-Gene tragen (mcr-1 bis mcr-10). Seit 2016 gilt Colistin als „Critically Important Antimicrobial" und dient als „Last Resort Antibiotica", daher ist die Bewertung von mcr-Genen sehr bedeutsam. Ziel dieser Untersuchung war es, 67 Vibrio-Isolate auf das Vorhandensein von mcr-Genen zu untersuchen. Zu Beginn erfolgte eine Speziesidentifikation der Isolate mit Hilfe der MALDI-TOF MS und eine MHK-Analyse, um die MHK-Werte gegen{\"u}ber Colistin zu ermitteln. Anschließend wurden die Isolate f{\"u}r die MiSeq-Sequenzierung vorbereitet. Dazu z{\"a}hlten die Verfahren der DNA-Extraktion und der Library Preparation, wobei in mehreren Schritten die Konzentrationen der DNA mittels Qubit und die DNA-L{\"a}ngen mit dem LabChip gemessen wurden. Nach der Sequenzierung folgte die bioinformatische Auswertung, durch die unter anderem die Sequenzauswertung, die Speziesidentifikation und die Auswertung von Resistenzgenen erfolgte. Im Rahmen dieser Arbeit konnte ein Vibrio-Isolat mit einem mcr-Gen identifiziert werden; dieses trug zus{\"a}tzlich die Resistenzgene almG, eptA, lpxN und gspIEF. Es handelt sich um ein mcr-4 Gen in einem Plasmid, welches bisher nicht beschrieben ist. Das Plasmid tr{\"a}gt katalytische Dom{\"a}nen von Mobilit{\"a}ts-Genen, die weder durch die NCBI-Datenbank noch durch andere Tools detektiert werden konnten. Folglich kann keine Risikoabsch{\"a}tzung bez{\"u}glich der Transferabilit{\"a}t des Plasmids erfolgen. Zus{\"a}tzlich zu diesem Ergebnis konnten putative neue chromosomale Resistenzgene ermittelt werden, die eine hohe {\"A}hnlichkeit zu den bisher bekannten mcr-Genen aufweisen. Eine weiterf{\"u}hrende Analyse hinsichtlich des unbekannten Plasmids und der m{\"o}glichen neuen Resistenzgene erfolgt.}, language = {de} } @masterthesis{Yotov, type = {Bachelor Thesis}, author = {Yotov, Nikola Vladislavov}, title = {Development of programmes to investigate the antimicrobial efficacy of domestic dishwashers}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:1383-opus4-13238}, school = {Hochschule Rhein-Waal}, pages = {85}, abstract = {Dishwashers have undergone a drastic change both in design and programme variation since their conception. Trends in water and energy conservation, as well as the public perception of topics such as environment protection, have pushed for a dishwashing service that delivers highly efficient cleaning while remaining ecologically friendly. Over the years, different methods have been used to assess the combined effects of different factors that play a role in the antimicrobial efficacy of domestic dishwashers. However, the extent of their individual capabilities remained unknown, as no factor could be tested separately with the commercially available settings. With the aid of a dishwasher with programmable parameters, a method was developed that would allow for the testing of the different factors in a way that separates their microbicidal activities from one another as much as possible. The work of cleaning agents was excluded from any trials, as they are expected to only benefit the microbial reduction. Furthermore, the methodology used in this thesis work presents an opportunity to investigate the energy consumption levels of different steps in traditional dishwashing processes and find potential targets for future reduction in water and energy usage. The study discovered that mechanical action, water quantity and the duration of the main cleaning cycle induce an equal reduction of around 4 logarithmic steps, when tested at room temperature. The main source of energy consumption during these experiments was found to be the spray arm pump with values 0.06 and 1.27 Wh per minute for the lowest and highest setting tested, respectively. The temperature increases caused the largest change in both logarithmic reduction and energy consumption. The highest achieved logarithmic reduction occurred during tests with a cleaning temperature of 75 ℃, with the value being roughly doubled to that of the tests at room temperature. The energy consumption values also drastically increase to a mean of 37 Wh during the heating part of the cycle. Overall, this method shows potential for discovering a combination of settings that can reduce the general energy consumption while retaining the antimicrobial efficacy of current programmes.}, language = {en} } @masterthesis{Mooren, type = {Bachelor Thesis}, author = {Mooren, Timo}, title = {Sample Collection Method for a Dispenser-Integrated Germ Detection System in the field of Hand Hygiene}, school = {Hochschule Rhein-Waal}, abstract = {This bachelor thesis validates a demonstrator that had a sample collection method for a dispenser-integrated germ detection system in the field of hand hygiene. In addition, the temperature of the hand was analysed; this was taken from previous work by T.Mooren. The first task was to validate a different spray nozzle. Eight nozzles were analysed by their spray patterns and ranked. Further experiments were carried out with the highest ranked spray nozzle. Subsequently, an attempt was made to prove whether bacteria could be washed off. This was done with an experimental setup to simulate washing off the palm of the hand, realised in the frame scope of this work. Calibrated glass slides with and without bacteria were used to enable localisation of the same bacterial areas before and after. Afterwards, this procedure was expanded to analyse the behaviour of soap and foam bacteria. The drip tray was changed to obtain a high number of bacteria into the sensing device. An excellent visual representation had to be achieved, so a mini-microscope was used in the demonstrator. This mini-microscope was able to capture and display images of the washed-off bacteria sample generation visually. Different lenses and that securitisation versions were tested for the microscope. Within this, the resolution of the pixels could be improved. Also, the comparison between two different objectives were evaluated. A complete electronic system was then integrated into a disinfection dispenser. This included a Raspberry-Pi and microcontroller for programming and controlling the system. Other components were the mini-microscope, a pump, LED-strips, two-infrared sensors for temperature measurements and an LCD-screen for visualisation. Finally, a fully functional system was presented to the funding agency the VDI/VDE-IT and to the employees of Ophardt Hygiene AG. The system was able to wash bacterial samples from a hand or a slide and display them visually with a microscope; the temperature of the hand was taken too. This 1st demonstrator of the project will be set up soon for Ophardt Hygiene AG employees to test at the building entrance in order to valuate long-term stability and user-friendliness. Data for the further project phases will be collected and determined there.}, language = {en} } @masterthesis{Geurts, type = {Bachelor Thesis}, author = {Geurts, Nick}, title = {Photodecompostion of Sodium Dodecyl Sulfate Using a UV/H2O2 Reactor with Ultraviolet-C Light Emitting Diodes}, school = {Hochschule Rhein-Waal}, abstract = {Anionic surfactants are used in many common household products, such as dishwashing detergents or soaps. Sodium dodecyl sulfate (SDS) is one of the most prominent surfactants and can cause substantial damage to the environment. Removal from wastewater is therefore a significant problem. This thesis investigates the photochemical decomposition of SDS using ultraviolet-c light emitting diodes (UV-C LEDs) and hydrogen peroxide. The experiments were performed with a surfactant concentration of 10 mg L which is actually found in wastewater after hand washing. Direct exposure to UV radiation to destroy organic compounds is generally seen as inefficient and consumes a large amount of energy. Adding hydrogen peroxide significantly increased the destruction rate due to the UV-induced formation of hydroxyl radicals. It was also investigated how the effectiveness of the reactor can be further increased. The use of a photocatalyst (titanium dioxide) improved the removal efficiency of SDS substantially. The data generated in this work indicates that using UV-C LEDs in a UV/H2O2 reactor works, and the process was significantly more efficient than only UV radiation. The ease of handling the diodes and implementing them into the reactor offers a significant advantage over other light sources. The standard SDS determination method is known to be very time-consuming. Therefore, a new approach was developed. This technique works faster than the commonly used one and has a low standard deviation. Photodecomposition of the investigated impurity is possible. In the future, development will concentrate on the realisation and system integration of UV/H2O2 reactors, as a common technology in the product family of OPHARDT Hygiene AG.}, language = {en} }