Physical processes of the CO2 hydrate formation and decomposition at conditions relevant to Mars

Diese Doktorarbeit befasst sich mit der Kinetik der Bildung und der Zersetzung sowie mit der Mikrostruktur von CO2-Hydrat unter p-T Bedingungen der Marsoberfläche und des Marsinneren. Sie wurde im Rahmen des DFG Projektes Ku 920/11 als Teil einer DFG-finanzierten Forschungsinitiative "Mars und die terrestrischen Planeten" (Schwerpunktprogramm 1115) durchgeführt.Die Wachstumskinetik wurde mit Neutronenbeugungs- und Gasverbrauchs-Messungen im Temperaturbereich von 185 K bis 272 K untersucht und die Ergebnisse der beiden Methoden auf Konsistenz geprüft. Darüber hinaus werden erste Ergebnisse von in situ Neutronbeugungsmessungen der CO2-Hydrat-Zersetzung präsentiert. Eine sigmoide Reaktionsentwicklung (Kinetik höherer Ordnung) wurde mehrfach sowohl bei der Bildung, als auch bei der Zersetzung beobachtet. Diese weist darauf hin, dass teilweise gleichzeitig Keimbildungs- und Wachstumsprozesse stattfinden. Die Asymmetrie der sigmoiden Form der Reaktionskurven zeigt zudem, dass Diffusionsprozesse eine wesentliche Rolle spielen. Mit einer erstmals hier vorgeschlagenen zweistufigen Methode für die Dateninterpretation (Stufe A: Kernbildung- und Wachstumstransformation und Stufe B: Diffusionskontrollierte Transformation) wird zum ersten Mal versucht, die theoretische Beschreibung von Bildungs- und Zersetzungsprozessen auf phänomenologischem Niveau zu vereinheitlichen. Die von anderen Autoren berichtete anormale Erhaltung von CO2-Hydrat wird bestätigt und erste Überlegungen zur Erklärung dieses Phänomens werden gegeben.. Die experimentellen Untersuchungen erlauben erstmals Vorhersagen des Umwandlungsverhaltens von CO2-Hydraten unter Marsbedingungen. So kann berechnet werden, dass ein Volumen von Eis mit einer spezifischen Oberfläche von ca. 0.1 m2/g bei Marsbedingungen, d. h. bei Temperaturen von 150 K und einem Druck um 6 mbar, in ca 10 000 J. zur Hälfte in CO2-Hydrat umgewandelt sein wird und in ca 90000 J. völlig transformiert. Im wesentlichen ist die Umwandlungskinetik dabei von der Diffusion der Bestandteile durch das kristalline Gashydrat bestimmt. Die anormale Erhaltung steht zwar zunächst den mehrfach zur Erklärung geomorphologischer Strukturen herangezogenen katastrophalen Zersetzungsprozessen von Gashydraten entgegen, der Effekt kann andererseits aber auch solche katastrophalen Prozesse fördern, indem er großen Mengen von Gashydraten metastabil erhält, die sich dann beim Überschreiten des Eisschmelzpunkts in katastrophaler Weise zersetzen.Spezielle Aufmerksamkeit wird in der Arbeit auch auf die Mikrostruktur der Gashydrate gerichtet. Zum ersten Mal wird ein Versuch für die Quantifizierung der Mikrostruktur basierend auf einer Beschreibung als teilweise offen-porigem Schaum präsentiert. Außerdem wird ein allgemeiner Bildverarbeitungsalgorithmus, der die schnelle Quantifizierung von im Rasterelektronenmikroskop beobachteten Schaumstrukturen zulässt, entworfen

Exponential Self-Organization and Moore\u27s Law: Measures and Mechanisms

The question of how complex systems become more organized and efficient with time is open. Examples are the formation of elementary particles from pure energy, the formation of atoms from particles, the formation of stars and galaxies, and the formation of molecules from atoms, of organisms, and of the society. In this sequence, order appears inside complex systems and randomness (entropy) is expelled to their surroundings. Key features of self-organizing systems are that they are open and they are far away from equilibrium, with increasing energy flows through them. This work searches for global measures of such self-organizing systems, which are predictable and do not depend on the substrate of the system studied. Our results will help to understand the existence of complex systems and mechanisms of self-organization. In part we also provide insights, in this work, about the underlying physical essence of Moore’s law and the multiple logistic growth observed in technological progress

A case of successful implant treatment of a patient with alcohol and tobacco addiction

The negative effects of smoking and poor oral hygiene on the outcome of implant placement can be related to many factors, and their mechanism can be mediated by both local and systemic biological pathways. The effects of smoking on the survival and success of implants are more pronounced in areas of poor trabecular bone quality. In this report, we present a case of a 64-year-old patient with low oral hygiene and multiple upper jaw gangrenous roots. Relatives reported that the patient suffers from chronic alcoholism and tobacco abuse. The patient insisted on implant treatment, which he was subsequently subjected to, although he is warned about the risks. The oral cavity was rehabilitated and the existing gangrenous roots were extracted under antibiotic therapy including penicillin. In the postoperative period, extremely good wound healing of the patient was observed, with no early or late bleeding.

Use of platelet-rich plasma in the treatment of medication-related osteonecrosis of the jaw. A case report

Introduction: Medication-related osteonecrosis of the jaw (MRONJ) is an area of uncovered bone in the maxillofacial region that does not heal within 8 weeks after identification by a healthcare provider, in a patient who is receiving or has been exposed to bisphosphonate therapy without previous radiation therapy to the craniofacial region. Case Description: The survey was conducted in 2018/2019. It was conducted at the Clinic of Maxillofacial Surgery, St. George University Hospital, Plovdiv, Bulgaria. In order to conduct thestudy, we obtained informed consent from the patient, who was 63 years of age. We have diagnosed medication-related osteonecrosis of the lower jaw. We performed bone resection and applied platelet-rich plasma (PRF) in order to enhance soft tissue healing. Discussion: Management of MRONJ remains a challenge and controversial topic. Multiple treatment approaches have been introduced to control MRONJ. Surgical treatment remains one of the most reliable methods but it also needs to take advantages of advanced scientific researches and technologies. One of these achievements is the use of a platelet-rich fibrin matrix (PRFM). Conclusion: In addition to the established surgical treatment options, we can add the application of platelet-rich plasma as an adjuvant treatment for MRONJ

On the Variability of the Temperature Coefficients of mc-Si Solar Cells with Irradiance

The temperature sensitivity of silicon solar cells is in general assumed to be constant with irradiance in PV forecasting models, although it has been demonstrated experimentally that this is not true. In this study a theoretical model is established that describes the variation of the temperature coefficients of a silicon solar cell as a function of the irradiance. It is shown that the temperature sensitivity of the solar cell efficiency is decreasing with the irradiance and that the main reason for this behavior comes from the increase of the open-circuit voltage with light intensity. Moreover, a dependency of the cell's ideality factor on the irradiance has to be assumed to receive good modelling results that can be confirmed experimentally

Studies of Electrical and Thermal Conductivities of Sheared Multi-Walled Carbon Nanotube with Isotactic Polypropylene Polymer Composites

Polymer nanocomposite materials of higher thermal and electrical transport properties are important to nanotechnology applications such as thermal management, packaging, labelling and the textile industry. In this work, thermal and electrical conductivities in nanocomposites of multiwalled carbon nanotubes (MWCNT) and isotactic polypropylene (iPP) are investigated in terms of MWCNT loading, temperature dependence, and anisotropy caused by melt shearing. IPP/MWCNT nanocomposites show a significant increase in thermal and electrical conductivity with increasing MWCNT loading, reaching 17.5 W/m K and 10−6 S/m, respectively, at a MWCNT 5.0 weight percentage at 40°C. The increase in MWCNT/iPP is more than would be expected based on the additivity rule, and suggests a reduction of the interfacial thermal electrical resistance at nanotube-nanotube junctions and the nanotube-matrix interface. The anisotropy in both conductivities was observed to be larger at low temperature and to disappear at higher temperature due to isotropic electrical and thermal contact in both directions. Oriented MWCNT/iPP nanocomposites exhibit higher electrical and thermal conductivities, attributed primarily by orientation of nanotubes due to the shearing fabrication process

Morphology of blood microbiota in healthy individuals assessed by light and electron microscopy

IntroductionThe blood microbiome is still an enigma. The existence of blood microbiota in clinically healthy individuals was proven during the last 50 years. Indirect evidence from radiometric analysis suggested the existence of living microbial forms in erythrocytes. Recently targeted nucleic acid sequencing demonstrated rich microbial biodiversity in the blood of clinically healthy individuals. The morphology and proliferation cycle of blood microbiota in peripheral blood mononuclear cells (PBMC) isolated from freshly drawn and cultured whole blood are obscure.MethodsTo study the life cycle of blood microbiota we focused on light, and electron microscopy analysis. Peripheral blood mononuclear cells isolated from freshly drawn blood and stress-cultured lysed whole blood at 43°C in presence of vitamin K from healthy individuals were studied.ResultsHere, we demonstrated that free circulating microbiota in the PMBC fraction possess a well-defined cell wall and proliferate by budding or through a mechanism similar to the extrusion of progeny bodies. By contrast, stress-cultured lysed whole blood microbiota proliferated as cell-wall deficient microbiota by forming electron-dense or electron-transparent bodies. The electron-dense bodies proliferated by fission or produce in chains Gram-negatively stained progeny cells or enlarged and burst to release progeny cells of 180 – 200 nm size. On the other hand, electron-transparent bodies enlarged and emitted progeny cells through the membrane. A novel proliferation mechanism of blood microbiota called by us “a cell within a cell” was observed. It combines proliferation of progeny cells within a progeny cell which is growing within the “mother” cell.DiscussionThe rich biodiversity of eukaryotic and prokaryotic microbiota identified in blood by next-generation sequencing technologies and our microscopy results suggest different proliferation mechanisms in whole and cultured blood. Our documented evidence and conclusions provide a more comprehensive view of the existence of normal blood microbiota in healthy individuals

Loosened hip joint prosthesis-decision options

For the period 2013-2015, 36 patients underwent revision surgery because of secondary developed complications after primary hip joint replacement surgery. 14 of them were male and 23 – female, with average age 73 years.  We examined 4 groups of patients depends on the complications type: - Aseptic loosening in 23 patients, appeared 10 years’ average following primary hip prosthesis surgery. - Septic loosening in 2 patients revealed on second to the tenth month post operatively. In two other patients we observed infected hematoma. - Hip joint prosthesis (luxation) because of trauma or extremely wrong motion we notice in 5 patients. In one of them we revealed acetabular cup malposition. - Periprosthetic fractures with aseptic loosening in 3 patients. All 36 patients had primary cemented hip joint prosthesis. In the first group depends on which prosthesis parts were loosened we did acetabular cup and femoral stem replacement in 15 patients, only acetabular cup replacement in 4 patients and in 3 patients only femoral stem replacement. In 2 patients from second group we replaced the primary prosthesis by total spacer for 8 months followed by revision prosthesis surgery. In 2 haematoma patients we performed debridement, lavage-drainage and long term antibiotic treatment. In 2 patients of third group we replaced the primary head with a longer one and in 3 other patients we replaced the primary acetabular cup by shoulder collar cemented cup. In 2 patients of fourth group we replaced the primary acetabular cup and femoral stem by shoulder collar cemented cup and by revisionary stem delivered by Implant and Zimmer (Revitan). In the third patient we implanted revisionary femoral stem (Implant). 3 years after revisionary hip joint prosthesis surgery we monitor good prosthesis stability and good functional score

Structural trends in atomic nuclei from laser spectroscopy of tin

Tin is the chemical element with the largest number of stable isotopes. Its complete proton shell, comparable with the closed electron shells in the chemically inert noble gases, is not a mere precursor to extended stability; since the protons carry the nuclear charge, their spatial arrangement also drives the nuclear electromagnetism. We report high-precision measurements of the electromagnetic moments and isomeric differences in charge radii between the lowest 1/2(+), 3/2(+), and 11/2(-) states in Sn117-131, obtained by collinear laser spectroscopy. Supported by state-of-the-art atomic-structure calculations, the data accurately show a considerable attenuation of the quadrupole moments in the closed-shell tin isotopes relative to those of cadmium, with two protons less. Linear and quadratic mass-dependent trends are observed. While microscopic density functional theory explains the global behaviour of the measured quantities, interpretation of the local patterns demands higher-fidelity modelling. Measurements of the hyperfine structure of chemical elements isotopes provide unique insight into the atomic nucleus in a nuclear model-independent way. The authors present collinear laser spectroscopy data obtained at the CERN ISOLDE and measure hyperfine splitting along a long chain of odd-mass tin isotopes.Peer reviewe