6 research outputs found
Boron containing vinyl aromatic polymers: synthesis, characterization and applications
No full textNovel luminescent polystyrene-based organoborane polymers were synthesized via facile silicon-boron exchange reactions with boron tribromide. The Lewis acidity as well as the photophysical properties of the polymers were then fine tuned by variation of the organic pi-system. The key step is a selective boron-tin exchange that allows for controlled and selective replacement of one of the bromine substituents by the chromophoric system, followed by substitution of the second bromine by a sterically hindered aryl group. The polymers and model compounds were fully characterized by multinuclear NMR spectroscopy. Molecular weights were determined by GPC. DSC and TGA were used to determine their thermal properties. Both polymers and model systems are highly emissive and UV-visible and fluorescence spectroscopy were used to ascertain their photophysical characteristics. To probe the use of the polymers as potential anion sensors, they were subjected to complexation with fluoride ([Bu4N]F in THF) and their complexation was studied by 11B NMR as well as UV-vis and fluorescence spectroscopy.
To counter the oxidative degradation of the systems a new strategy was adapted in which we prepared stannylcarbazole precursors which would act as chromophores. To further enhance the stability of the boron center in these systems the mesityl group was replaced by the bulkier 1,3,5-triisopropylphenyl group. The models and polymers synthesized show superior stability as compared to the compounds synthesized earlier. The compounds are also highly emissive in the blue region.
Systems that contain electroactive ferrocenyl groups in the side-chain of polystyrene were also synthesized. Cyclic voltammetry studies confirm the electroactive nature of these polymers. A quasi-reversible boron redox couple and a ferrocene-centered redox process were observed.
Finally, a trimethylsilyl-functionalized vinyl bithiophene monomer was prepared. This monomer was polymerized by a variety of methods including standard free radical polymerization (BPO, AIBN), via nitroxide-mediated polymerization (NMP) and also by anionic polymerization. Moderate molecular weights in the range of 4000 – 9000 were obtained.Ph.D.Includes bibliographical references (p. 146-161)by Kshitij K. Para
Steering Torque Determination of Pulling Open Thrusters
No full textThe use of azimuth thrusters as main propulsion device and for manoeuvring of ships is increasing over the past decades. However, the understanding of hydrodynamic loads acting on such devices in oblique inflow conditions is still an interesting area of research as it is generally believed that such loads can be partially responsible for the failure of parts of power transmission system to the thruster. A deeper understanding of such loads can provide critical mechanical design considerations for the parts involved in transmitting power such as bevel gears, bearing and seals as well the parts of thruster housing. Thus, the aim of this research is to provide an insight into the behavior of hydrodynamic loads of a pulling open type steerable thruster particularly the steering moment, including extreme oblique inflow conditions at various ship speeds and power absorption. A numerical investigation of steering thrusters is performed for various conditions. For this a turbulence model is used and for simulating manoeuvring tests transient conditions are used where as open water tests are simulated using quasi steady conditions. These simulations are based on RANS method for solving the flow with standard k-epsilon model with a high y+ wall treatment around an azimuth thruster system. A commercial code of Star CCM+ is used for performing the simulations. Post processing results give an insight into the critical flow regions and contribution of loads and moments of the system. Validation is done with available model scale data, tested at MARIN institute at Netherlands. The results showed an acceptable agreement to do further analysis of the steering moment behaviour at various steering angles and advance ship speeds. Behaviour of various hydrodynamic loads is discussed in the results section. In general, the various hydrodynamic forces were found to be increasing with increase in steering angles and symmetrical for mirrored conditions. As numerical simulations provide the feasibility of studying loads on individual components, the contribution of individual parts of the thruster for different forces and moments was also analyzed. The side force moment created by the propeller side is balanced mainly by anti moments created by the skeg and the remainder is taken up by the steering motor torque to keep the thruster at a particular steering position under such external hydrodynamic loads. Detailed asymmetrical flow fields are discussed which arise due to oblique angle and spinning of fluid due to propeller rotation. Finally, the pulling thruster under study was compared with a ducted pushing thruster for hydrodynamic loads and the results are discussed in detail. The steering moments in both cases rise very steeply with steering angles and are significant at higher steering angles. Also, in case of a pulling thruster there is a fluctuating steering moment present even in straight inflow conditions unlike the pushing unit, which can be of interest when comparing these two type of configurations.Energy Technology/Fluids chairProcess and EnergyMechanical, Maritime and Materials Engineerin
Thermal Modelling of Existing Residential Buildings in North Western Europe
No full textA study by the Building Performance Institute Europe(BPIE) stated that upgrading old housing stock to higher energy efficiency through renovations and smart interventions would be a significant step towards meeting Europe’s Greenhouse Gas (GHG) reduction goals. Since 2011 Shell Global Solutions is investigating deep decarbonisation strategies for the residential sector through the EcoGenie project. The EcoGenie project constitutes an extreme learning position in order to determine cost-effective, socially beneficial and renewable options for residential heating systems for the immediate future. The Shell EcoGenie house has been under operation for the last 4 years where it is being used to test out new energy technologies available in the market and collect data about the energy use, occupancy and indoor climate. Based on the work of Bacher and Madsen, 2011, this research investigates the complexity and accuracy of dynamic thermal modelling with the objectives to predict the future heating demand and to identify sources of heat loss in the house. Using indoor/outdoor climate data, energy consumption data and prior knowledge about the heat transfer mechanisms, an initial thermal model is developed and its parameters are estimated by applying statistical solution algorithms based on the maximumlikelihood method. The estimated parameters represent physical properties of the building such as window area, heat capacities and thermal resistances. A hierarchy of models with increasing levels of complexity is investigated and suitable models are identified based on maximum likelihood values, statistical tests, data size and physical interpretation of the properties. The estimated parameters are discussed to understand the heat dynamics of the house. It is concluded that the heat capacity of the building envelope and its interaction with its adjacent components (indoor and outdoor air) significantly influences the heat dynamics of the house. In addition, a thermal resistance mechanism to model the effect of air leakage in existing houses, i.e. unwanted exchange of warm indoor air, is proposed and successfully applied. Future research is required to differentiate and to quantify conductive and convective heat transfer mechanism of air leakages. This research proposes a thermal model that forecasts the thermal behaviour of a residential building - the EcoGenie house - to predict its heating requirements for up to 48 hours. Additional sub-models are investigated to account for meaningful physical model boundaries and model improvements that simulate the heating system’s control mechanisms are tested with the objective to improve prediction accuracies. Further research should be considered into simulating controllers that can capture effects of rapid temperature changes, both indoor and ambient temperatures. Finally, and with an outlook to future management of smart grids and smart cities infrastructures, future research is needed to investigate and to build a library of thermal models which includes a large cross-section of existing building archetypes to account for diverging structural and physical properties of the building stock. The aggregated heating energy demands of buildings will be instrumental to ensure integration of and safe and secure supply of renewable energy sources.Electrical Engineering, Mathematics and Computer ScienceElectrical Sustainable Energy / Intelligent Electrical Power GridsSustainable Energy Technolog
A RP-HPLC Method for the Analysis of Neostigmine Methylsulfate and Process-Related Impurities, Forced Degradation Studies, in the Injection Formulation
No full textNeostigmine methylsulfate is an anticholinesterase agent and is clinically used for treating myasthenia gravis. It is also used for reversing nondepolarising neuromuscular blocking agents. Neostigmine methylsulfate may be administered by intravenous, intramuscular, or subcutaneous injection. In this research paper, a distinct stability-indicating reverse phase HPLC method was developed and validated for the quantitative determination of related impurities and degradation impurities in neostigmine methylsulfate API and injection formulation. The specific objective was to improve the resolution between European Pharmacopoeia listed impurity A and impurity B and degradation impurity of neostigmine methylsulfate API and injection formulation. The analysis was performed using Kromasil C18 column at 30°C of column oven temperature with phosphate-buffer/acetonitrile in a gradient mode. The RP-HPLC method was developed and validated for in-house neostigmine methylsulfate synthesis process sample and injection formulation. The injection formulation sample was studied for accelerated stability, temperature cycling stability, and photostability. The validation studies for neostigmine methylsulfate synthesis process API were studied using impurity A, impurity B, and impurity C. The analytical method validation parameters studied were specificity, precision, linearity, limit of detection, limit of quantitation, accuracy, and robustness. The API and the injection formulation were subjected to forced degradation under acid, alkali, oxidation, and photolytic and thermal conditions. The proposed method showed a significantly improved RRT (Relative Retention Time) of impurity A and impurity B with a resolution greater than 1.5. The developed method eliminates the use of an ion-pairing agent and thereby a good performance of column was established
Time Critical Team Training in Virtual Worlds
No full textabstract: In the modern age, where teams consist of people from disparate locations, remote team training is highly desired. Moreover, team members' overlapping schedules force their mentors to focus on individual training instead of team training. Team training is an integral part of collaborative team work. With the advent of modern technologies such as Web 2.0, cloud computing, etc. it is possible to revolutionize the delivery of time-critical team training in varied domains of healthcare military and education. Collaborative Virtual Environments (CVEs), also known as virtual worlds, and the existing worldwide footprint of high speed internet, would make remote team training ubiquitous. Such an integrated system would potentially help in assisting actual mentors to overcome the challenges in team training. ACLS is a time-critical activity which requires a high performance team effort. This thesis proposes a system that leverages a virtual world (VW) and provides an integrated learning platform for Advanced Cardiac Life Support (ACLS) case scenarios. The system integrates feedback devices such as haptic device so that real time feedback can be provided. Participants can log in remotely and work in a team to diagnose the given scenario. They can be trained and tested for ACLS within the virtual world. This system is well equipped with persuasive elements which aid in learning. The simulated training in this system was validated to teach novices the procedural aspect of ACLS. Sixteen participants were divided into four groups (two control groups and two experimental groups) of four participants. All four groups went through didactic session where they learned about ACLS and its procedures. A quiz after the didactic session revealed that all four groups had equal knowledge about ACLS. The two experimental groups went through training and testing in the virtual world. Experimental group 2 which was aided by the persuasive elements performed better than the control group. To validate the training capabilities of the virtual world system, final transfer test was conducted in real world setting at Banner Simulation Center on high fidelity mannequins. The test revealed that the experimental groups (average score 65/100) performed better than the control groups (average score 16/100). The experimental group 2 which was aided by the persuasive elements (average score 70/100) performed better than the experimental group 1 (average score 55/100). This shows that the persuasive technology can be useful for training purposes.Dissertation/ThesisM.S. Computer Science 201
Retrospective Study to Determine Factors Influencing Outcome in Patients With Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer Receiving Neoadjuvant Chemotherapy
No full textPURPOSEThere are scant data on patients with human epidermal growth factor receptor 2 (HER2)–positive breast cancer treated with neoadjuvant therapy (NAT) in real-world settings with limited access to HER2-targeted therapy.METHODSThis was a retrospective analysis of patients with nonmetastatic, HER2-positive breast cancer treated with NAT between January 2014 and December 2018 to determine factors affecting pathologic complete response (pCR), event-free survival (EFS), and overall survival (OS).RESULTSThe cohort comprised 1,004 patients with a median age of 47 years, 533 (53.1%) with clinical T3/T4 tumors, 466 (46.4%) with clinical N2/3 status, and 527 (52.5%) with hormone receptor–positive disease. Trastuzumab was given to 528 (52.6%) patients in the neoadjuvant setting and 711 (70.8%) patients in neoadjuvant and/or postoperative settings. pCR was achieved in 226 (22.5%) patients; the 5-year EFS in the whole cohort, pCR group, and no-pCR group was 63.5% (95% CI, 60.36 to 66.63), 86.1% (95% CI, 81.59 to 90.60), and 57% ([95% CI, 53.47 to 60.52]; P < .001), respectively. In multivariable analysis in the full cohort, smaller tumor size (cT1/T2 v cT3/T4), higher grade (III v II), hormone receptor–negative status, and use of neoadjuvant HER2-targeted therapy were significantly associated with higher pCR, and smaller tumor size (cT1/T2 v cT3/T4), lower node involvement (cN0/N1 v cN2/N3), achievement of pCR, and receiving trastuzumab were significantly associated with higher EFS and OS.CONCLUSIONIn a setting with constrained access to HER2-targeted therapy, lower clinical tumor burden and receiving trastuzumab were significantly associated with increased pCR and survival in patients with HER2-positive breast cancer treated with NAT. Efforts should be made to enhance early diagnosis and access to HER2-targeted therapy worldwide
