186,369 research outputs found
An experimental and kinetic modeling study of 2-methyltetrahydrofuran flames
No full textMoshammer K, Vranckx S, Chakravarty HK, Parab P, Fernandes RX, Kohse-Höinghaus K. An experimental and kinetic modeling study of 2-methyltetrahydrofuran flames. COMBUSTION AND FLAME. 2013;160(12):2729-2743
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
Preventing type 2 diabetes microvascular complications: Exploring the interplay of racial/ethnic disparities and primary therapeutic interventions
No full textType 2 Diabetes Mellitus (T2DM) persists as a major public health issue capable of producing a variety of adverse complications. The prevalence of T2DM microvascular complications, such as kidney, nerve, and eye problems, is higher in the U.S. than macrovascular complications such as heart disease. Racial/ethnic disparities in the prevalence of T2DM microvascular complications has been reported by prior studies. Because treatment for T2DM microvascular complications is still in the developmental phase, it is critical to prevent the development of T2DM complications in at-risk populations to reduce disparities. Diet, physical activity, and drug (i.e., metformin) are often prescribed to treat T2DM. These T2DM interventions may lower risk of microvascular complications over time; however, findings from clinical and epidemiologic studies have been inconsistent. Furthermore, the effects of these interventions on risk may vary by race/ethnicity, but information in the scientific literature on this topic is scarce. The overarching aim of this dissertation project is to examine longitudinal associations between basic preventive interventions and risk of microvascular complications at the intersection of race/ethnicity. Using data from the National Heart Lung and Blood Institute, this dissertation project will address three specific aims. The first aim will analyze longitudinal trajectories of T2DM microvascular complications across racial/ethnic groups over a period of seven years. The second aim will investigate the individual and combined effects of lifestyle interventions (i.e., diet and physical activity) and metformin on risk of T2DM microvascular complications over a four-year period to identify the best preventive intervention. And finally, the third aim will examine racial/ethnic differences in the effects of the best intervention derived from aim two to determine if this intervention equitably reduces risk of microvascular complications for racial/ethnic groups. Overall, this project will identify racial/ethnic groups at increased risk for T2DM microvascular complications and the role of basic preventive intervention in reducing racial/ethnic disparities. The estimated timeline of completion is spring 2023. A detailed summary of the background and methods for each specific aim are provided below.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-05-01The student, Kaustubh Parab, accepted the attached license on 2024-04-17 at 12:17.The student, Kaustubh Parab, submitted this Dissertation for approval on 2024-04-17 at 12:38.This Dissertation was approved for publication on 2024-04-18 at 13:30.DSpace SAF Submission Ingestion Package generated from Vireo submission #20458 on 2024-09-16 at 00:49:3
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Edward P. Wimberly, ITC, July 2011
No full textThis video is a conversation with Dr. Edward P. Wimberly. Dr. Wimberly talks about his book, "No Shame in Wesley's Gospel: A Twenty-First Century Pastoral Gospel". Brad Ost, AUC Woodruff Library, is the interviewer
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