In Situ RheoNMR Correlation of Polymer Segmental Mobility with Mechanical Properties during Hydrogel Synthesis

Understanding polymer gelation over multiple length-scales is crucial to develop advanced materials. An experimental setup is developed that combines rheological measurements with simultaneous time-domain $^{1}$H NMR relaxometry (TD-NMR) techniques, which are used to study molecular motion (<10 nm) in soft matter. This so-called low-field RheoNMR setup is used to study the impact of varying degrees of crosslinking (DC) on the gelation kinetics of acrylic acid (AAc) and N,N′-methylene bisacrylamide (MBA) free radical crosslinking copolymerization. A stretched exponential function describes the T$_{2}$ relaxation curves throughout the gelation process. The stretching exponent β decreases from 0.90 to 0.67 as a function of increasing DC, suggesting an increase in network heterogeneity with a broad T$_{2}$ distribution at higher DC. The inverse correlation of the elastic modulus G′ with T2 relaxation times reveals a pronounced molecular rigidity for higher DC at early gelation times, indicating the formation of inelastic, rigid domains such as crosslinking clusters. The authors further correlate G′ with the polymer concentration during gelation using a T$_{1}$ filter for solvent suppression. A characteristic scaling exponent of 2.3 is found, which is in agreement with theoretical predictions of G′ based on the confining tube model in semi-dilute entangled polymer solutions

Conversion of ileo-pouch anal anastomosis to continent ileostomy: strategic surgical considerations and outcome

Aim: The aim was to evaluate surgical strategies for conversion of failed ileo-pouch anal anastomosis (IPAA) to continent ileostomy (CI), taking morbidity and overall outcome into account. The hypothesis was that complex conversions are equivalent to the primary construction of a CI at the time of proctocolectomy. Method: This was a retrospective analysis of IPAA conversions acknowledging the underlying disease (inflammatory bowel disease [IBD] and non-IBD) and extent of pouch reconstruction (PR): type 1 (without PR), type 2 (partial PR), and type 3 (complete PR). Results: Twenty-six patients (IBD, n = 16; non-IBD, n = 10) were converted (type 1, n = 13; type 2, n = 7; and type 3, n = 6).12/26 patients (46.2%) presented postoperative complications directly related to the conversion with scarification of two pouches. In a mean follow-up time of 7.5 ± 6.6 years, 5/24 patients required revisional surgery. Of these, three required pouch excision. The cumulative probability of reoperation at the end of the second year increased to 21.7% and remained constant thereafter until the maximum follow-up time of 26 years. The total pouch loss rate was 19.2% (5/26), of which all occurred in the first 3 years. No statistically significant differences were found between the conversion types, complications or pouch survival. For all parameters, IBD patients performed slightly unfavourably. Due to the overall small number of respective patients, a differentiated investigation of IBD was not performed. Conclusion: Complex conversion procedures (types 1 and 2) deliver comparable longterm results to new constructions (type 3), thereby limiting the loss of small bowel. IBD compromises outcome versus non-IBD

In vitro Untersuchungen zur Rolle des MER-Tyrosinkinase-Rezeptors bei der Leukämie / ZNS Interaktion der akuten lymphatischen Leukämie (ALL) im Kindesalter

Die Mer-TK wurde in zahlreichen Studien mit Überlebenssignalwegen von soliden und hämatologischen Tumorerkrankungen in Verbindung gebracht. Mit der vorliegenden Arbeit sollte die Frage beantwortet werden, ob sich in vitro Hinweise auf einen Zusammenhang zwischen einer ZNS-Beteiligung und der Expression der Mer-TK im Rahmen der t(1;19)+ B-Zell-Vorläufer ALL finden. Zu diesem Zweck wurde ein Kokulturmodell etabliert, in dem die ZNS-Nische durch Glia Zellen (U343: Gemischtes Astrozytom/Oligodendrogliom und NRA: Neonatale Ratten-Astrozyten) imitiert und das Verhalten von B-Vorläufer ALL Zellen mit unterschiedlichen Mer-Expressionsniveaus untersucht wurde. Die erhobenen in vitro Daten liefern erste Erkenntnisse über die Mer-TK als diagnostischen Marker und therapeutisches Target für einen ZNS Befall der t(1;19)+ B-Zell-Vorläufer ALL im Kindesalter. Darüber hinaus konnte gezeigt werden, dass der Mer-Ligand Galectin-3 hochreguliert wird und damit als Mer-Aktivator in diesem Modell in Frage kommt

Untersuchungen zu den Auswirkungen im ersten und zweiten Folgejahr nach einer einmalig variierten Bodenbearbeitung auf Ertragsbildung, Verunkrautung und Nitratauswaschung unter ökologischen Produktionsbedingungen

Einleitung Die Belastungen des Trinkwassers haben in den letzten Jahren stark zugenommen. Durch pflanzenbauliche Maßnahmen sollen die Nitratausträge aus landwirtschaftlich genutzten Flächen auf einem möglichst geringen Niveau gehalten werden. Reduzierte Bodenbearbeitung, späte Bearbeitungstermine und Begrünungsgebote stellen einen wesentlichen Teil dieser Maßnahmen dar. Ökologisch wirtschaftende Betriebe sind in ihren Anbauverfahren zur Förderung der Ertragsbildung, zur Unkrautregulation und zur Kontrolle von Schaderregern und Schädlingen auf eine zeit- und bedarfsgerechte Bodenbearbeitung angewiesen. Dies steht zum Teil im Widerspruch zu den oben genannten Regelungen. Ziel der Untersuchung ist es, zu überprüfen, ob bestimmte Bodenbearbeitungsverfahren zu erhöhten N- Austrägen führen und ob durch die Anwendung nitratreduzierender Maßnahmen eine Beeinträchtigung der Anbauverfahren im Ökologischen Landbau entsteht

Radar-absorbent properties of a foam glass with gallium arsenide addition

The principal possibility of using wastes of semiconductor devices production containing gallium arsenide as a component of radio-absorbing material was established. The composition formulation including perlite, liquid glass, complex blowing agent and waste is developed. It is shown that with increase the waste amount in the composition from 10 to 30 wt. % the absorption coefficient increases from 80 to 98%, the transmission coefficient decreases to zero. The obtained results indicate a high absorbing capacity of composite in the frequency range of 120 - 260 GHz that refers to ultrasonic waves

Live broadcasting in cardiac surgery does not increase the operative risk

Objective: Live broadcasting of cardiac surgical procedures has an educational intention. There is an ongoing debate whether live surgery increases risk. Aim of this study was to evaluate the outcomes of patients who underwent a cardiac surgical procedure during live broadcasting. Methods: A total of 250 cardiac operations were performed during 32 live broadcastings at four different clinical sites between 1999 and 2009. Data on patient characteristics, intra-operative procedures and patient short- and long-term outcome were collected and analyzed. All participating centers complied with the rules for the conduct of live surgery developed by the European Association of Cardiovascular and Thoracic Surgery (EACTS) Techno College Committee. Results: Primary educational focus was the mitral valve in 126 cases, aortic valve including transcatheter valve implantations in 34, coronary artery bypass grafting (CABG) in 29, congenital in 26, aortic (ascending, arch, and descending) in 15, atrial fibrillation in 13, and heart failure in seven. Mean EuroSCORE (European System for Cardiac Operative Risk Evaluation) was 8.7±11.5 (range: 0.8-72). Thirty-day mortality was 1.2% (3/250): reasons for death were multi-organ failure in two and respiratory failure in one patient, respectively. Stroke rate was 2.4% (6/250). Five patients (2%) required cardiac re-operations within 30 days. The rate of mitral valve repair was 96% (121) and compares favourably with repair rates presented in national registries. Mean follow-up of all patients was 3.7±2.8 years with an estimated survival of 92% (95% confidence interval (CI): 87-95%) at 5 years. Conclusions: Based on this large experience there is no evidence for an excess perioperative risk for patients operated under the conditions of live broadcastin

Электропривод вентиляционной установки стояночного бокса

Разработана структура и модель асинхронного электропривода вентиляционной установки стояночного бокса. Проведено математическое моделирование режимов работы электроприводаThe structure and model of asynchronous electric drive ventilation installation of the parking box. Mathematical modeling of the modes electric drive operatio

Твердофазно-спектрофотометрическое определение ртути с использованием дифенилкарбазона

Объектом исследования является полимерный датчик с иммобилизированным реагентом для определения ионов ртути. Целью работы является создание оптического сенсора для твёрдофазно-спектрофотометрического определения ртути на основе полимерной матрицы. В процессе выполнения магистерской диссертации проведен анализ существующих методов определения ртути, проверена возможность применения твердофазной спектрофотометрии для определения ионов ртути, подобраны оптимальные условия иммобилизации реагента (время, pH), получены калибровочные зависимости, рассмотрены вопросы ресурсоэффективности и безопасности данного исследования.The object of the study is a polymer sensor with an immobilized reagent for the determination of mercury ions. The aim of the work is to create an optical sensor for solid-phase-spectrophotometric determination of mercury based on a polymer matrix. During execution master thesis analyzed existing mercury determination methods verified the possibility of applying solid phase spectrophotometry to determine the mercury ions, optimal conditions are selected immobilization reagent (time, pH), prepared according to the calibration, the issues of security and resource efficiency of the study