Fachbereich Ingenieur- und Naturwissenschaften
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Solutions to the 3D Model Problem of Pressure Measurement in the Area of Maxillary Sinus Anastomosis
(2020)
The ostiomeatal complex (OMC) is a key area that determines the occurrence of inflammatory processes in the paranasal sinuses (PNSs). The aim of our work was to develop a procedure for studying the OMC components in the preoperative period that allows for identification the impact of anatomical peculiarities on change of physiological pressure in the maxillary sinus. Materials and methods: The study was carried out on the basis of the otorhinolaryngological department of Kharkiv Regional Clinical Hospital in 2019-2020. It involved 100 patients of both sexes aged 20-59 years with chronic non-polyposis maxillary sinusitis. Results: The sizes of the uncinate process, the middle turbinate and the natural anastomosis were determined using the calculation of uncertainty. Basing on the data obtained, all the patients were divided into three groups. Conclusions: Changes in the size of the natural anastomosis (both an increase and its narrowing) lead to changes in pressure in the area of the anastomosis, and a decrease in ventilation in the paranasal sinuses. SCT study with subsequent 3D modeling is an informative, accurate and effective method for assessment of OMC and PNSs condition. It allows surgeons to presume the method and volume of surgery as early as at the preoperative stage, without resorting to invasive research methods.
Optical and microwave waveguides have attracted much research interest in both science and industry. The number of potential applications for their use is growing rapidly. This book examines recent advances in the broad field of waveguide technology. It covers current progress and latest breakthroughs in emergent applications in photonics and microwave engineering. The book includes ten contributions on recent developments in waveguide technologies including theory, simulation, and fabrication of novel waveguide concepts as well as reviews on recent advances.
Nowadays pharmaceutical analysis and industry could not be imagined without using chromatographic methods like the High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC). Therefore, the field of chromatography is already firmly anchored in the three important, regional pharmacopeias: EP, USP and JP. Deficits of specifications within these pharmacopoeias relating to the detector parameters sampling rate and signal filtration are the major motivation of this thesis. Furthermore investigations on the data acquisition and processing within the detectors and software products dealing with collected data were done. Several concepts like double entry method, smoothing optimization and signal filtration based on persistence have been developed and are used as tools to examine the data integrity of commercial Chromatography Data System (CDS), improve the signal-to-noise ratio of small peaks to lower the LOD and LOQ by efficient denoising, and determine the suitable filter parameters and sampling rates an user can apply on his system to accelerate the method development and validation. All developments have been tested on simulated and real chromatograms and have shown that they are suitable for their specific purposes. In the end optimizations in the concepts still exist but some new aspects in the long-term investigated field of chromatography have been discovered.
Biomass fuel is the major source of energy for a significant proportion of the world population. Conventionally, biomass is burned in combustors that use air as oxidizer. The need for efficiency and reduced emissions has led to development of clean combustion technologies such as oxy-fuel combustion. In oxy-fuel combustion technique, fuel is burnt in O2/CO2 environment instead of O2/N2 environment. In spite of biomass being used under oxy-fuel conditions using fixed bed furnaces, there is no detailed study of biomass combustion in fixed bed reactors under oxy-fuel condition. The studies only cover combustion under air-fuel condition. There is no report in the literature on important combustion parameters, viz., flame propagation speed, temperature profiles, ignition time, and species evolution in the fixed bed combustion under oxy-fuel conditions; the studies have been only in air. This work extends the research on biomass conversion to combustion under oxy-fuel conditions. To address these knowledge gaps, this PhD thesis focused on establishing and isolating the role of various CO2 effects on biomass combustion properties using a laboratory fixed bed reactor through experiments and numerical modeling. The fixed bed reactor used in this study was operated in counter-current flame propagation mode. Oxidizer was a mixture of pure O2 and N2 or CO2. Measurement were made for air-fuel condition, oxy-fuel condition of different O2/CO2 mixtures and various initial bed porosity. In this work, all numerical simulations were carried out using a commercial CFD software CD-Adapco (STAR CCM+ version 11.04). Euler-Lagrange (CFD-DEM) approach was used to model biomass conversion in a packed bed. Solid particles and their conversion were modeled using DEM while fluid phase was modeled as a continuous phase using CFD. Biomass conversion was modeled by four sub-models, namely, drying, pyrolysis, gas-phase reactions and char oxidation models. These models were adopted and improved from previous research on wood combustion. To account for oxy-fuel combustion environment, reaction involving CO2 which has been identified as the dominant reaction pathway as well as its associated chain-branching reactions were incorporated in homogeneous reaction sub-model. In order to separate effects of CO2 on wood combustion, four different mixtures of O2 and Ar/CO2/N2 were designed and simulated. Temperature in O2/CO2 combustion environment was adjusted to be equal to that of O2/N2 environment by adding an appropriate amount of Ar while O2 amount remained the same. The results showed that flame front propagation speed in oxy-fuel atmosphere reduced to 78% of that of the air-fuel condition with similar O2 concentration. The CFD-DEM model agreed very well with experimental values for mass loss, propagation speed and flame front positions. However, peak temperatures were poorly predicted at lower oxygen concentrations. The accuracy of temperature prediction improved at higher oxygen concentrations. It was noted that oxy-fuel peak temperature is lower than air-fuel temperature by about 200 K. For oxy-fuel combustion, peak temperature value and propagation speed increases as O2 concentration is increased. The results showed that at any given oxygen concentration, ignition time in oxy-fuel environment is almost twice that of corresponding air-fuel condition. It was established that the packing density affects combustion process by changing the burning conditions and limits. Furthermore, the study revealed that there is an optimum packing density, χ = 0.71, beyond which the efficiency falls due to the onset of quenching in the spaces. It was concluded that dilution effect is the most influential parameter on the burning rate of wood combustion in an oxy-fuel system. In a future study, the model prediction could be improved by including ash inhibition sub-model and using a full chemical kinetic mechanism for hydro-carbon combustion. It was also recommended that a detail analysis of heat transfer in the bed could be investigated in a future study. The findings from this work are important and may be useful when designing burners which operate under oxy-fuel combustion conditions.
This work presents experimental and simulation results of a 3D measurement concept based on fiber-optic interference pattern generation. A demonstrator system which is able to adjust different optical and mechanical parameters is described. The results of parameter variation studies are discussed along with possible applications in the field of micro-optical 3D measurement systems like endoscopes. The experiments were prepared with different structures with various scattering properties. To implement that approach into a micro-optical 3D measurement system, the combination of distance variation between the fibers and a controlled phase shift introduced by a retarder can be used to design the system versatile.
A reliable energy supply for the economy of every country is a matter of national importance. Powerful simulation tools for natural gas networks are essential for operators of gas networks. In this paper, enhancement algorithms of previous developed node potential analysis algorithm are presented. These enhancement algorithms are used for a reasonable setting of initial values in the numerical gas net simulation algorithm. The setting of the initial values has a significant influence on the convergence behavior of the numerical simulation. The presented enhancement algorithms are explained and simulation results are evaluated.
Today, academic researchers benefit from the changes driven by digital technologies and the enormous growth of knowledge and data, on globalisation, enlargement of the scientific community, and the linkage between different scientific communities and the society. To fully benefit from this development, however, information needs to be shared openly and transparently. Digitalisation plays a major role here because it permeates all areas of business, science and society and is one of the key drivers for innovation and international cooperation. To address the resulting opportunities, the EU promotes the development and use of collaborative ways to produce and share knowledge and data as early as possible in the research process, but also to appropriately secure results with the European strategy for Open Science (OS). It is now widely recognised that making research results more accessible to all societal actors contributes to more effective and efficient science; it also serves as a boost for innovation in the public and private sectors. However for research data to be findable, accessible, interoperable and reusable the use of standards is essential. At the metadata level, considerable efforts in standardisation have already been made (e.g. Data Management Plan and FAIR Principle etc.), whereas in context with the raw data these fundamental efforts are still fragmented and in some cases completely missing. The CHARME consortium, funded by the European Cooperation in Science and Technology (COST) Agency, has identified needs and gaps in the field of standardisation in the life sciences and also discussed potential hurdles for implementation of standards in current practice. Here, the authors suggest four measures in response to current challenges to ensure a high quality of life science research data and their re-usability for research and innovation.
Characterization and Tests of Different Mach-Zehnder Silicon Photonic Modulator Configurations
(2020)
We designed and produced an integrated silicon photonic circuit, in a single chip with IHP SG25H4_EPIC 0.25 µm technology. A Mach-Zehnder interferometer with an alternative shape for better integration, together with a standard-shape Mach-Zehnder interferometer have been realized. In this work, preliminary results of comparative performance measurements between the two Mach-Zehnder interferometer are shown.
In dem Artikel geht es um die gegenwärtige Sprachsituation im Wissenschaftsbereich in Deutschland u.a. europäischen Ländern. Die sich abzeichnende funktionale Diglossie – Englisch für Gebildete, Landessprachen für den Rest – wirkt sich nachteilig für die Kommunikation zwischen Wissenschaft und Gesellschaft. Besonders systemrelevant ist dabei der Bereich der Hochschullehre. Das sprachliche Abheben des Hochschullehrbetriebes von der Gesellschaft führt zur Desintegration der landeseigenen Bildungselite und schwächt den gesellschaftlichen Zusammenhalt. Für die ausländischen Studierenden und bleibewilligen Absolventen erhöhen rein englischsprachige Studiengänge das Studienabbruchrisiko, sie hemmen ihre Integration und benachteiligen sie auf dem deutschen Arbeitsmarkt. Die absehbaren Folgen einer fehlgeleiteten Sprachenpolitik, die anstelle der akademischen Mehrsprachigkeit die alternativlose Einführung von englischsprachigen Studiengängen an den Hochschulen fördert und dies gleichzeitig zur Internationalisierung verklärt, werden in dem Artikel verdeutlicht.
This review presents the 100-year history of the Martsinovsky Institute of Medical Parasitology and Tropical Medicine in Moscow, Russia, starting with its foundation and early activities, and also describes the impact of its leading scientists, some of whom became internationally known. The institute headed a network of nine tropical institutes in the various Soviet republics from the 1920s to 1990. The extensive body of literature on the history and research accomplishments of this institute has mainly been published in Russian; our goal here is to introduce these achievements and this expertise to the international scientific and medical community, focusing on malaria and leishmaniasis and the development of measures to control and monitor these diseases in the USSR.
We investigate polyhedral aspects of the Periodic Event Scheduling Problem (PESP), the mathematical basis for periodic timetabling problems in public transport. Flipping the orientation of arcs, we obtain a new class of valid inequalities, the flip inequalities, comprising both the known cycle and change-cycle inequalities. For a point of the LP relaxation, a violated flip inequality can be found in pseudo-polynomial time, and even in linear time for a spanning tree solution. Our main result is that the integer vertices of the polytope described by the flip inequalities are exactly the vertices of the PESP polytope, i.e., the convex hull of all feasible periodic slacks with corresponding modulo parameters. Moreover, we show that this flip polytope equals the PESP polytope in some special cases. On the computational side, we devise several heuristic approaches concerning the separation of cutting planes from flip inequalities. We finally present better dual bounds for the smallest and largest instance of the benchmarking library PESPlib.
CMOS-Compatible Silicon Photonic Sensor for Refractive Index Sensing Using Local Back-Side Release
(2020)
Silicon photonic sensors are promising candidates for lab-on-a-chip solutions with versatile applications and scalable production prospects using complementary metal-oxide semiconductor (CMOS) fabrication methods. However, the widespread use has been hindered because the sensing area adjoins optical and electrical components making packaging and sensor handling challenging. In this work, a local back-side release of the photonic sensor is employed, enabling a separation of the sensing area from the rest of the chip. This approach allows preserving the compatibility of photonic integrated circuits in the front-end of line and metal interconnects in the back-end of line. The sensor is based on a micro-ring resonator and is fabricated on wafer-level using a CMOS technology. We revealed a ring resonator sensitivity for homogeneous sensing of 106 nm/RIU.
Pepper bacterial spot is one of the most severe plant diseases in terms of infection persistence and economic losses when it comes to fresh pepper fruits used in nutrition and industrial processing. In this study, Bacillus velezensis IP22 isolated from fresh cheese was used as a biocontrol agent of pepper bacterial spot, whose main causal agent is the cosmopolitan pathogen Xanthomonas euvesicatoria. After optimization of the cultivation medium composition aimed at maximizing of the antimicrobial activity against X. euvesicatoria and validation of the optimized medium at the scale of a laboratory bioreactor, in planta tests were performed. The results have showed significant suppression of bacterial spot symptoms in pepper plants by the produced biocontrol agent, as well as reduction of disease spreading on the healthy (uninoculated) pepper leaves. Furthermore, HPLC-MS (high pressure liquid chromatography–mass spectrometry) analysis was employed to examine antimicrobial metabolites produced by B. velezensis IP22, where lipopeptides were found with similar m/z values compared to lipopeptides from fengycin and locillomycin families. The bioprocess solution developed at the laboratory scale investigated in this study represents a promising strategy for production of pepper bacterial spot biocontrol agent based on B. velezensis IP22, a food isolate with a great perspective for application in plant protection.
The coupling of biological entities with electrodes has already quite some history and has reached a status which is not only based on phenomenological descriptions. Nowadays, we are able to effectively couple redox centres within protein molecules to electrochemical transducers. This allows the transduction of a biochemical reaction into an electrode signal with applications mainly in sensing and bioenergetics [1,2,3,4,5,6,7,8]. However, in most cases, this coupling is not direct, and shuttle molecules or side products of the reaction are used. But also for the direct coupling, significant progress has been made, and several enzymes and redox proteins can be addressed directly by electrodes [8,9,10,11,12,13]. The understanding of the functioning of developed systems is, however, in its infancy. Charge and electrostatic interactions have been mostly studied, and for small dipole molecules such as cytochrome c, the situation can be well described [14]. There is a lack of understanding for more complex enzyme molecules which brings a lot of trial and error into research.
Trimeric photosystem I from the cyanobacterium Thermosynechococcus elongatus (TePSI) is an intrinsic membrane protein, which converts solar energy into electrical energy by oxidizing the soluble redox mediator cytochrome c6 (Cyt c6) and reducing ferredoxin. Here, we use cryo-electron microscopy and small angle neutron scattering (SANS) to characterize the transient binding of Cyt c6 to TePSI. The structure of TePSI cross-linked to Cyt c6 was solved at a resolution of 2.9 Å and shows additional cofactors as well as side chain density for 84% of the peptide chain of subunit PsaK, revealing a hydrophobic, membrane intrinsic loop that enables binding of associated proteins. Due to the poor binding specificity, Cyt c6 could not be localized with certainty in our cryo-EM analysis. SANS measurements confirm that Cyt c6 does not bind to TePSI at protein concentrations comparable to those for cross-linking. However, SANS data indicate a complex formation between TePSI and the non-native mitochondrial cytochrome from horse heart (Cyt cHH). Our study pinpoints the difficulty of identifying very small binding partners (less than 5% of the overall size) in EM structures when binding affinities are poor. We relate our results to well resolved co-structures with known binding affinities and recommend confirmatory methods for complexes with KM values higher than 20 μM.
Sand flies (Diptera: Psychodidae: Phlebotominae) are blood-feeding insects that transmit the protozoan parasites Leishmania spp. and various arthropod-borne (arbo) viruses. While in Mediterranean parts of Europe the sand fly fauna is diverse, in Central European countries including Austria mainly Phlebotomus mascittii is found, an assumed but unproven vector of Leishmania infantum. To update the currently understudied sand fly distribution in Austria, a sand fly survey was performed and other entomological catches were screened for sand flies. Seven new trapping locations of Ph. mascittii are reported including the first record in Vienna, representing also one of the first findings of this species in a city. Morphological identification, supported by fluorescence microscopy, was confirmed by two molecular approaches, including sequencing and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) protein profiling. Sand fly occurrence and activity were evaluated based on surveyed locations, habitat requirements and climatic parameters. Moreover, a first comparison of European Ph. mascittii populations was made by two marker genes, cytochrome c oxidase subunit 1 (COI), and cytochrome b (cytb), as well as MALDI-TOF mass spectra. Our study provides new important records of Ph. mascittii in Austria and valuable data for prospective entomological surveys. MALDI-TOF MS protein profiling was shown to be a reliable tool for differentiation between sand fly species. Rising temperatures and globalization demand for regular entomological surveys to monitor changes in species distribution and composition. This is also important with respect to the possible vector competence of Ph. mascittii.
Research publications and data nowadays should be publicly available on the internet and, theoretically, usable for everyone to develop further research, products, or services. The long-term accessibility of research data is, therefore, fundamental in the economy of the research production process. However, the availability of data is not sufficient by itself, but also their quality must be verifiable. Measures to ensure reuse and reproducibility need to include the entire research life cycle, from the experimental design to the generation of data, quality control, statistical analysis, interpretation, and validation of the results. Hence, high-quality records, particularly for providing a string of documents for the verifiable origin of data, are essential elements that can act as a certificate for potential users (customers). These records also improve the traceability and transparency of data and processes, therefore, improving the reliability of results. Standards for data acquisition, analysis, and documentation have been fostered in the last decade driven by grassroot initiatives of researchers and organizations such as the Research Data Alliance (RDA). Nevertheless, what is still largely missing in the life science academic research are agreed procedures for complex routine research workflows. Here, well-crafted documentation like standard operating procedures (SOPs) offer clear direction and instructions specifically designed to avoid deviations as an absolute necessity for reproducibility.
Therefore, this paper provides a standardized workflow that explains step by step how to write an SOP to be used as a starting point for appropriate research documentation.
Impact of inorganic nanoparticles on optical properties of low refractive index waveguiding polymers
(2020)
The objective of this work is to improve the optical properties of low refractive index polymers used for waveguide by introduction of inorganic nanoparticles. Copolymers of fluorinated monomers and glycidyl methacrylate are used. Introduction of SiO2 nanoparticles into polymer matrix is performed by direct mixing; copolymerization with SiO2 nanoparticles modified by monomer, and in situ sol-gel formation of SiO2 during photochemical cross-linking and annealing catalyzed by photoacid generator. It is demonstrated that nanoparticles are able to decrease thermo-optic coefficient. It is also possible to fabricate waveguiding layers by direct introduction of nanoparticles without compromising of optical propagation losses.
In this work we present a novel optical polymer system based on polyurethane elastomer components, which combines excellent UV transparency with high thermal stability, good hardness, high surface tension and long pot life. The material looks very promising for encapsulation and microlensing applications for chip-on-board (CoB) light-emitting diodes (LED). The extinction coefficient k, refractive index n, and bandgap parameters were derived from transmission and reflection measurements in a wavelength range of 200-890 nm. Thermogravimetry and differential scanning calorimetry were used to provide glass transition and degradation temperatures. The surface tension was determined by means of contact angle measurements. As proof of concept, a commercial InGaN-CoB-LED is used to demonstrate the suitability of the new material for the production of microlenses.