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Title: GROWTH, SURVIVAL, AND INACTIVATION OF LISTERIA MONOCYTOGENES IN HUMMUS
Creator: Mhetras, Tanvi
Date: 2018, 2018-05
Description: Listeria monocytogenes is widely spread in the environment and is the causative agent of listeriosis. L. monocytogenes can contaminate ready...
Show moreListeria monocytogenes is widely spread in the environment and is the causative agent of listeriosis. L. monocytogenes can contaminate ready-to-eat (RTE) foods such as dairy products, salad dips, sandwiches, and seafood. In recent years, various recalls of hummus products have been reported to be associated with L. monocytogenes. This study aimed to 1) assess survival of L. monocytogenes on individual dry ingredients (chickpeas and sesame seeds), 2) examine survival of the pathogen in individual wet ingredients (mashed chickpeas and tahini) of hummus; 3) to evaluate L. monocytogenes survival in complete hummus dips; and 4) to determine L. monocytogenes inactivation in hummus dip using high pressure processing (HPP). Dry hummus ingredients (chickpeas and sesame seeds) were inoculated with a cocktail of four L. monocytogenes strains and stored at relative humidity (RH) levels of 25, 45, and 75% RH at 25 C for 28 d. When inoculated at 10 log CFU/g, L. monocytogenes populations decreased significantly (P<0.05) on sesame seeds and chickpeas in the first 24 h. The pathogen was more resistant to survival on sesame seeds at each of the RH levels than on chickpeas. The lowest D-value observed for L. monocytogenes was 9.90 d on chickpeas at 45% RH, while the highest value was 35.87 d on sesame seeds at 75% RH. When inoculated onto wet ingredients of hummus (mashed chickpeas and tahini), hummus dip, and hummus made using contaminated tahini or mashed chickpeas at 2 log CFU/g, L. monocytogenes was capable of survival in tahini during 28 d storage at 10 C. In mashed chickpeas, however, the pathogen increased significantly by approximately 4 log CFU/g after 7 d and had a growth rate of 2.21±1.34 log CFU/g/d. In hummus dip, L. monocytogenes had a significantly lower growth rate (0.11±0.01 log CFU/g/d) than in the mashed chickpeas. In hummus made using contaminated mashed chickpeas, the L. monocytogenes population significantly increased by 1.16 log CFU/g after 14 d. In hummus made using contaminated tahini, L. monocytogenes was capable of surviving, but did not grow. Hummus dip was treated with HPP at 350 MPa with holding times of 60,120,180 and 240 s. The D-value for L. monocytogenes was determined to be 98.2 seconds. The results from this study will aid in determining how L. monocytogenes survives in Refrigerated RTE hummus and its individual dry and wet ingredients. The study will also help in assessing the use of HPP for inactivation of L. monocytogenes in contaminated hummus.
M.S. in Food Safety and Technology, May 2018
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Title: ELASTIC ELEMENTS IN THE SARCOMERES OF STRIATED MUSCLE
Creator: Ma, Weikang
Date: 2016, 2016-07
Description: The flight muscle of the Hawkmoth, Manduca sexta, is an emerging model system for structure and function studies. M. sexta flight muscle shows...
Show moreThe flight muscle of the Hawkmoth, Manduca sexta, is an emerging model system for structure and function studies. M. sexta flight muscle shows several interesting properties such as its length tension curve is similar with cardiac muscle, but the detailed protein compositions of M. sexta flight muscle is not known. Here we identified proteins that might be responsible for the elastic properties of M. sexta flight muscle. 1% vertical SDS-agarose gel electrophoresis combined with western blot analysis was used to separate and identify high molecular weight proteins in M. sexta flight muscle. Two projectin isoforms as well as two kettin isoforms were found in M. sexta flight muscle. In addition, two high molecular weight proteins were seen in agarose gels which turned out to be Sallimus (Sls) proteins isoforms based on the sallimus (sls) gene map. The localization and orientation of projectin and Sallimus proteins were determined by immuno-localization using confocal microscopy. The thin and thick filament lengths were also determined, and shown to be consistent with the length tension curve data. Knowledge of myofilament compliance is critical in interpreting cross bridges kinetics interpretation and modeling. Here we used small angle X-ray diffraction to study thick filament compliance in intact mouse soleus muscle. The thick filament compliance was estimated by plotting the spacing changes of myosin based meridional reflections against tension generated by the muscle during contraction. A non-linear relationship of thick filament compliance was seen for the first time. Nebulin is a giant thin filament protein and has been proposed to play significant roles in muscle physiology, but the underlying mechanisms are largely unknown. A conditional nebulin gene knockout mouse model was used here to study any structural and functional changes caused by nebulin deficiency using small angle X-ray diffraction. The thin filament compliance was estimated, and the results showed that the thin filament compliance in nebulin deficient muscle was larger than muscle from control animals, whereas no difference was seen in thick filament compliance between knockout and control muscles. The inter-filament spacing was larger in knock out muscle than in control muscle, and less force was generated by each cross bridge. The larger interfilament spacing and less force per cross bridge might explain the muscle weakness seen in both the knock out mouse model, as well as in nemaline myopathy patients. Other structural changes caused by nebulin deficiency was also characterized by small angle X-ray diffraction.
Ph.D. in Molecular Biochemistry and Biophysics, July 2016
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Title: SUSTAINABLE URBAN DESIGN WITHIN CONTEMPORARY URBAN POLICY: A COMPARATIVE STUDY BETWEEN CHICAGO AND TAIPEI
Creator: Cheng, Chien-ke
Date: 2013, 2013-05
Description: This research and methodology develop a set of statistical measurements to evaluate sustainability – in terms of desired high urban density,...
Show moreThis research and methodology develop a set of statistical measurements to evaluate sustainability – in terms of desired high urban density, walkability for community amenity and convenience for everyday life – at the level of urban design for the cities of Chicago, USA and Taipei, Taiwan. The method, based upon GIS (Geographical Information System) technology, is used at this spatial level and for this type of academic study for the first time. The research analyzes and compares the percentage of each city’s population living within the “Quarter Mile Radius Sphere of Influence” (QMSI) for three classes of community amenities: parks, public elementary schools, and subway stations. The new and unique statistical data obtained in this thesis show a great disparity between the two cities. 1. Chicago has 31.98% of its population living within the QMSI of public elementary schools. Taipei has 49.64% of its population living within the QMSI of public elementary schools. 2. For subway stations, Chicago has only 8.09% of its population living in the QMSI, while Taipei has 25.99%. 3. For urban parks, Chicago has 44.06% of its population living in the QMSI, while Taipei has 88.80%. Further, based upon comparison, this research also discovers that the “sweet spot” areas – intersection of the QMSIs of all three community amenities – are mostly distributed along subway lines. With this indication, the research visualizes and supports the objective of improved public transit and walkability as key factors for sustainability in urban design in this case. The research also demonstrates the usefulness of GIS April 16, 2013 p.0B-xi PDD TF 0 20130416-13.doc xi technology’s new application in urban design studies for the future. The research shows that this new method has applicability for academic studies in other urban contexts, and for future international urban design and planning.
PH.D in Architecture, May 2013
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Title: ON THE LIST COLORING PROBLEM AND ITS EQUITABLE VARIANTS
Creator: Mudrock, Jeffrey Allen
Date: 2018, 2018-05
Description: In this thesis we study list coloring which was introduced independently by Vizing and Erd˝os, Rubin, and Taylor in the 1970’s. Suppose we...
Show moreIn this thesis we study list coloring which was introduced independently by Vizing and Erd˝os, Rubin, and Taylor in the 1970’s. Suppose we associate a list assignment L with a graph G which assigns a list, L(v), of colors to each v 2 V (G). A proper L-coloring of G, f, is a proper coloring such that f(v) 2 L(v) for each v 2 V (G). The list chromatic number of G, "`(G), is the minimum k such that G has a proper L-coloring whenever L is a list assignment satisfying |L(v)| ' k for each v 2 V (G). A graph G is said to be chromatic-choosable if "`(G) = "(G). The list chromatic number of the Cartesian product of graphs is not well understood. The best result is by Borowiecki, Jendrol, Kr´al, and Miˇskuf (2006) who proved that the list chromatic number of the Cartesian product of two graphs can be bounded in terms of the list chromatic number and the coloring number of the factors. In Chapter 2, we use the Alon-Tarsi Theorem and an extension of it discovered by Schauz in 2010 to find improved bounds on the list chromatic number and paint number (i.e. online list chromatic number) of the Cartesian product of an odd cycle or complete graph with a traceable graph. We also identify certain Cartesian products as chromatic-choosable. In Chapter 3, we generalize the notion of strong critical graphs, introduced by Stiebitz, Tuza, and Voigt in 2008, to strong k-chromatic-choosable graphs, and we show that it gives a strictly larger family of graphs that includes odd cycles, cliques, the join of a clique and any strongly chromatic-choosable graph, and many more families of graphs. We prove sharp bounds on the list chromatic number of certain Cartesian products where one factor is a strong k-chromatic-choosable graph satisfying an edge bound. Our proofs rely on the notion of unique-choosability as a sufficient condition for list colorability and the list color function which is a list analogue of the chromatic polynomial.In Chapter 4, we study a list analogue of equitable coloring introduced by Kostochka, Pelsmajer, and West in 2003. A graph G is said to be equitably kchoosable if it has a proper L-coloring that uses no color more than d|V (G)|/ke times whenever |L(v)| = k for each v 2 V (G). Generalizing a conjecture of Fu (1994) on total equitable coloring, we conjecture that for any simple graph G, its total graph, T(G), is equitably k-choosable whenever k ' max{"`(T(G)),"(G) + 2}. We prove this conjecture for all graphs satisfying "(G)  2 while also studying the related question of the equitable choosability of powers of paths and cycles. In Chapter 5, we introduce a new list analogue of equitable coloring: proportional choosability. For this new notion, the number of times a color is used must be proportional to the number of lists in which the color appears. Proportional kchoosability implies both equitable k-choosability and equitable k-colorability. Also,the graph property of being proportionally k-choosable is monotone, and if a graph is proportionally k-choosable, it must be proportionally (k +1)-choosable. We study the proportional choosability of graphs with small order and disconnected graphs, and we completely characterize proportionally 2-choosable graphs.
Ph.D. in Applied Mathematics, May 2018
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Title: SURVIVAL OF LISTERIA MONOCYTOGENES AND ESCHERICHIA COLI O157:H7 DURING AGING OF GOUDA CHEESE MADE USING UNPASTEURIZED MILK
Creator: Natarajan, Vidya
Date: 2018, 2018-05
Description: The FDA code of federal regulations states that cheeses made using unpasteurized milk must be aged for a period of at least 60 days to...
Show moreThe FDA code of federal regulations states that cheeses made using unpasteurized milk must be aged for a period of at least 60 days to minimize the inherent risks associated with unpasteurized milk. However, there have been several foodborne outbreaks associated with 60-day aged semi-soft cheeses made using unpasteurized milk, specifically Gouda cheese. In this study, Gouda cheese was manufactured using unpasteurized milk artificially-inoculated with Listeria monocytogenes (1 or 3 log CFU/mL) and Escherichia coli O157:H7 (1 log CFU/mL). The Gouda cheese was pressed, brined, waxed, and aged at 10°C for 90 (for the 1 log CFU/mL) or 150 (for the 3 log CFU/mL) days. Samples were assessed during cheese manufacture and aging for survival of the pathogen as well as for the population dynamics of the native microflora including Enterobacteriaceae, yeast and mold, lactic acid bacteria, and mesophilic bacteria. In addition, cheese samples during aging were also analyzed for property characteristics including salt and moisture content, fat in solid content, pH, and water activity. Results determined that the population levels of both pathogens significantly increased during manufacture. During aging of the Gouda cheese, E. coli O157:H7 was capable of survival only until 49 days and was henceforth not detected via enrichment. For L. monocytogenes, pathogen populations were 2.07±0.12 log and 1.26±0.00 log CFU/g at 60 and 90 days of aging, respectively, for the 1 log CFU/mL initial inoculation level. Compared to day 60 (2.31±0.92 log CFU/g) of aging, the population of L. monocytogenes for the Gouda cheese made with the 3 log CFU/mL initial inoculation level was significantly higher (p<0.05) on both 90 and 150 d of aging (4.62±0.25 and 6.00±0.72 log CFU/g, respectively). During aging, the populations of lactic acid and mesophilic bacterial were significantly higher than other microflora categories. The population of yeast and mold displayed an increasing trend in population, whereas Enterobacteriaceae populations were highly unsteady. Increases in lactic acid bacterial populations were accompanied by decreases in pH and pathogen populations. These results indicate that the characteristics of Gouda cheese and the native microflora population may play a pivotal role in survival and growth of pathogens. Overall, this study suggests that the current 60-day aging regulation, while sufficient to control E. coli O157:H7, may not be suitable to control the risk of L. monocytogenes in Gouda cheese.The population of yeast and mold displayed an increasing trend in population, whereas Enterobacteriaceae populations were highly unsteady. Increases in lactic acid bacterial populations were accompanied by decreases in pH and pathogen populations. These results indicate that the characteristics of Gouda cheese and the native microflora population may play a pivotal role in survival and growth of pathogens. Overall, this study suggests that the current 60-day aging regulation, while sufficient to control E. coli O157:H7, may not be suitable to control the risk of L. monocytogenes in Gouda cheese.
M.S.in Food Safety and Technology, May 2018
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Title: INITIAL VALIDATION OF AN OBSERVATIONAL MEASURE OF TEMPERAMENT IN PRESCHOOL-AGED CHILDREN
Creator: Plumb, Nora
Date: 2018, 2018-05
Description: Literature has shown that temperament predicts a range of childhood outcomes, including social competence, academic performance, and empathic...
Show moreLiterature has shown that temperament predicts a range of childhood outcomes, including social competence, academic performance, and empathic responsiveness. Temperament also has been consistently shown to be a risk factor for psychopathology (e.g., externalizing disorders, conduct problems, anxiety, and depression). Although there is general agreement on the definition of temperament, there are still aspects of this construct that are disputed (e.g., the specific traits involved and the degree to which they are stable across development). Moreover, researchers also have developed different strategies to assess this construct, specifically parent-report and direct observation, both of which have their limitations. Despite these limitations, very few measures temperament measures utilize ecologically valid observations in naturalistic settings. The purpose of this study was threefold. The first aim was to examine the construct validity of a newly-developed behavioral observation measure of temperament through confirmatory factor analysis (CFA). The second aim was to determine if the measure was invariant across age and gender. Finally, the third aim was to assess the measures’ convergent and predictive validity. This measure was administered to 796 children across three ages (i.e.,ages 4, 5, and 6). Results from the CFAs revealed that a four-factor structure was the best fit to the data at age 4, therefore supporting configural invariance across gender for that age group. Invariance testing also showed that the measure demonstrated metric, but not scalar, invariance across gender at age 4. Finally, this study found evidence for both convergent and predictive validity for this measure. Directions for future research are also discussed.
M.S. in Psychology, May 2018
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Title: IDENTIFICATION OF SURROGATE MICROORGANISMS AND USE OF PERACETIC ACID IN EXTENDED SHELF LIFE REFRIGERATED HIGH-ACID JUICE AND BEVERAGE PROCESSING
Creator: Stachler, Donna
Date: 2018, 2018-05
Description: The present study aim is to identify a surrogate microorganism that could be used in validation studies for Extended Shelf Life (ESL) chilled...
Show moreThe present study aim is to identify a surrogate microorganism that could be used in validation studies for Extended Shelf Life (ESL) chilled juice beverages with Peracetic Acid (PAA) in the processing system. Historically, Bacillus atrophaeus has been the primary surrogate, especially for aseptic systems with PAA; nevertheless this organism may be overly conservative for ESL processing that doesn’t have as high thermal temperature or PAA concentration. A baseline study was conducted to determine PAA resistance for B. atrophaeus spores. After being heat shocked at 82°C (179.6°F) for 13 minutes, 106 colony forming units per milliliters (CFU/mL) spores were spot inoculated and dried on stainless steel coupons. Then submerged in 200 ppm and 500 ppm VigorOx LS-15® PAA concentration, in two minute increments up to ten minute exposure time, at 50°C (122°F). The PAA reaction was halted and remaining spores were plated on Dextrose Tryptone Agar supplemented with yeast extract (DTA+ye), then incubated at 30°C (86°F) for 24 h. B. atrophaeus is PAA resistant and at least three log CFU/mL reduction was achieved for both concentrations at ten min exposure time. The next phase of the study was the selection of 15 different Bacillus species to conduct similar PAA resistance testing (with exposure time reduced to two and four minutes and additional 100 ppm of PAA) in an effort to evaluate which had the largest potential to be studied further. The three selected were B. pumilus, B. licheniformis (A) and B. licheniformis (B), due to high PAA resistance and similarity to B. atrophaeus inactivation. The three microorganisms were then studied against spoilage microorganisms (Aspergillus niger and Saccharomyces cerevisiae) and pathogenic microorganisms (Listeria monocytogenes, Salmonella species, and Escherichia coli O157:H7) at 200 ppm and 500 ppm PAA concentration. It was concluded that B. licheniformis (B) was the best overall surrogate with half log CFU/mL reduction at one minute and 200 ppm, as it was more resistant to PAA than A. niger and Salmonella. At 500 ppm PAA concentration B. atrophaeus continues to be best surrogate. Further studies, including testing to verify the behavior of B. licheniformis, as a surrogate, are recommended.
M.S. in Food Processing Engineering, May 2018
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Title: Adoption and Implementation of Diabetes Electronic Support Center at Mount Sinai Hospital, Summer 2011, IPRO 345: IPRO project plan
Creator: Kos, Carolyn, Valio, Nicole, Michael, Hazel, Chinzorig, Unubold, Johnson, Kendra
Date: 2011-06-17, 2011-07
Description: The purpose of IPRO 345 is to improve and mobilize the data and remote health care system for Mount Sinai Hospital. Specifically, this project...
Show moreThe purpose of IPRO 345 is to improve and mobilize the data and remote health care system for Mount Sinai Hospital. Specifically, this project aims to create a data support to aid diabetic patients within 500 meters of the hospital in order to decrease cost of operation and time and increase the quality of care. We will develop the groundwork for future IPRO 345 teams that will eventually implement the new data collection program.
Sponsorship: SolarWindUSA
Design+Prototype+Test an Integrated Roof-Top Photovoltaic Solar System Design, Summer 2011, IPRO 345
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Title: Adoption and Implementation of Diabetes Electronic Support Center at Mount Sinai Hospital, Summer 2011, IPRO 345: Midterm powerpoint
Creator: Kos, Carolyn, Valio, Nicole, Michael, Hazel, Chinzorig, Unubold, Johnson, Kendra
Date: 2011-06-17, 2011-07
Description: The purpose of IPRO 345 is to improve and mobilize the data and remote health care system for Mount Sinai Hospital. Specifically, this project...
Show moreThe purpose of IPRO 345 is to improve and mobilize the data and remote health care system for Mount Sinai Hospital. Specifically, this project aims to create a data support to aid diabetic patients within 500 meters of the hospital in order to decrease cost of operation and time and increase the quality of care. We will develop the groundwork for future IPRO 345 teams that will eventually implement the new data collection program.
Sponsorship: SolarWindUSA
Design+Prototype+Test an Integrated Roof-Top Photovoltaic Solar System Design, Summer 2011, IPRO 345
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Title: Adoption and Implementation of Diabetes Electronic Support Center at Mount Sinai Hospital, Summer 2011, IPRO 345: ipro 345 ethics
Creator: Kos, Carolyn, Valio, Nicole, Michael, Hazel, Chinzorig, Unubold, Johnson, Kendra
Date: 2011-06-17, 2011-07
Description: The purpose of IPRO 345 is to improve and mobilize the data and remote health care system for Mount Sinai Hospital. Specifically, this project...
Show moreThe purpose of IPRO 345 is to improve and mobilize the data and remote health care system for Mount Sinai Hospital. Specifically, this project aims to create a data support to aid diabetic patients within 500 meters of the hospital in order to decrease cost of operation and time and increase the quality of care. We will develop the groundwork for future IPRO 345 teams that will eventually implement the new data collection program.
Sponsorship: SolarWindUSA
Design+Prototype+Test an Integrated Roof-Top Photovoltaic Solar System Design, Summer 2011, IPRO 345
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Title: Beam Line Design for Fully Staged Two Beam Acceleration at the Argonne Wakefield Accelerator Facility
Creator: Neveu, Nicole
Date: 2018
Description: Two beam acceleration (TBA) is a candidate for future high energy physics machines and FEL user facilities. This is a scheme in which an...
Show moreTwo beam acceleration (TBA) is a candidate for future high energy physics machines and FEL user facilities. This is a scheme in which an electron accelerator uses a ``drive'' beam to transport and supply the RF power needed for acceleration on a secondary and independent 'witness' accelerator. This technology is attractive for its potential to improve the efficiency and simplicity of large scale machines. At the Argonne Wakefield Accelerator Facility (AWA), research into this potential accelerator scheme is ongoing. Completed experiments include a simplified staging set up, where high-charge, 65 MeV drive bunch trains were injected from the RF photoinjector into decelerating structures to generate a few hundred MW's of RF power. This RF power was transferred through an RF waveguide to accelerating structures that were used to accelerate the witness beam. Staging refers to the sequential acceleration (energy gain) in two or more structures on the witness beam line. The main limitation in past experiments was difficulty achieving 100\% transmission in the second stage which resulted in lower power generation. AWA plans to demonstrate fully staged TBA, which requires a separate beam line for each decelerating/accelerating pair. In this thesis, design specifications and initial hardware tests needed for a new, independent beam line for TBA was done. Simulations of the drive line were done using the code OPAL. Since OPAL was new to the AWA group, a benchmark comparison with ASTRA and GPT was done to validate initial results. Then two optimization algorithms were investigated and used to optimize the drive line at 40 nC. Comparison of results between the two algorithms were done, with no major discrepancies found. Then large scale and parallel optimizations were done for the optics configuration in the fully staged TBA beam line design. A kicker was designed and incorporated into the drive beam line to accomplish a modular design so that each accelerating structure can be independently powered by a separate drive beam. Experimental measurements of the kicker indicate the angle increases linearly with the supplied voltage, and the angle achieved meets the design requirements for fully staged TBA. Optics optimization was done to minimize the beam size at the center of the decelerating structures to ensure good charge transmission. The resulting design will be the basis for proof of principle experiments that will take place at the AWA facility.
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Title: LOW DIMENSIONAL SIGNAL SETS FOR RADAR APPLICATIONS
Creator: Alphonse Joseph Rajkumar, Sebastian Anand
Date: 2018
Description: In this dissertation we present a view in which the radar signals as the elements of a high dimensional signal set. The dimension is equal to...
Show moreIn this dissertation we present a view in which the radar signals as the elements of a high dimensional signal set. The dimension is equal to the number of discrete samples (M) of the signal. Because the radar signals should satisfy certain conditions for good performance, most lie in much smaller subsets or subspaces. By developing appropriate lower dimensional signal spaces that approximate these areas where the radar signals live, we can realize potential advantage because of the greater parametric simplicity. In this dissertation we apply this low dimensional signal concept in radar signal processing. In particular we focus on radar signal design and radar signal estimation. Signal design comes under radar measures and signal estimation comes under radar countermeasures.In signal design problem one searches for the signal element that has smaller sidelobes and also satisfies certain constraints such as bandwidth occupancy, AC mainlobe width, etc. The sidelobe levels are quantified by Peak Sidelobe Ratio (PSLR) and Integrated Sidelobe Ratio (ISLR). We use linear combination of these two metrics as the cost function to determine the quality of the designed signal. There is a lot of effort in designing parameterized signal sets including our proposed Asymmetric Time Exponentiated Frequency Modulated (ATEFM) signal and Odd Polynomial FrequencySignal (OPFS). Our contribution is to demonstrate that the best signal elements from these low dimensional signal sets (LDSS) mostly outperform the best signal elements that are randomly chosen from the radar signal subset with dimensionality M. Since searching the best signal element from the LDSS requires less computational resources it is prudent to search for the best signal elements from the low dimensional signal sets.In signal estimation problem we try to estimate the signal transmitted by a noncooperating radar which is intercepted by multiple passive sensors. The intercepted signals often have low SNR and there could be only few intercepted signals available for signal estimation. Predominantly used method for estimating the radar signals is Principal Component Analysis (PCA). When the SNR is low (< 0 dB) we need large number of intercepted signals to get an accurate estimates from PCA method. Our contribution is to demonstrate that by limiting the search for the best signal estimate within the low dimensional signal sets one can get more accurate estimates of the unknown transmitted signal at low SNRs with smaller number of sensors compared to PCA.
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Title: Structural Studies of Degradation Mechanism of Lithium Rich Manganese, Nickel, and Iron Based Cathodes
Creator: Aryal, Shankar
Date: 2018
Description: Layered oxide compounds are superior with respect to discharge voltage and discharge specific capacity compared to other families of cathodes....
Show moreLayered oxide compounds are superior with respect to discharge voltage and discharge specific capacity compared to other families of cathodes. Therefore, LiCoO2 and LiMnxNiyCozO2, are the most commonly used cathodes since the commercialization of lithium ion battery. Recently, Li rich Ni, Mn, and Co oxide composite cathodes have been introduced with some improvements. As Co is toxic and expensive, attempts have been made to replace Co with cheap and environmentally friendly Fe. This dissertation reports that comparable discharge specific capacity and discharge voltage can be achieved by replacing Co with Fe and optimizing the composition of Mn, Ni, and Fe. However, the capacity and voltage fading on cycling are still remaining challenges. Structural change on electrochemical cycling is the main reason behind this fading. X-ray absorption spectroscopy (XAS), the specific element probe technique to study local structure and X-ray diffraction (XRD) to study the crystallographic phase information are utilized to understand the degradation/aging mechanism. A series of Li rich Mn, Ni, and Fe oxide composite cathode materials Li1.2Mn(0.30+x)Ni(0.40-x)Fe0.10O2 for x = 0, 0.05, 0.10, 0.15, 0.20 and 0.25 were prepared using a sol-gel synthesis method. Rhombohedral and monoclinic crystal phases are found in Li rich Mn, Ni, and Fe composite oxide materials, but pure rhombohedral phase cannot be obtained without excess Li in the stoichiometric LiMO2 form. The pure monoclinic phase Li2MnO3 is also synthesized to confirm its presence in the composite oxide cathodes. Particle size and surface morphology are studied with scanning electron microscopy. The composite cathodes are cycled to over 100 cycles at 0.3C, for C = 250 mAhg-1 rate. XAS before and after 100 electrochemical cycles of Li rich Mn-Ni-Fe based cathodes is reported for the first time. The determination of fractional contents of monoclinic and rhombohedral phases in the composite oxide cathodes is not possible by powder XRD analysis, however, Li2MnO3 content decreases on decreasing Mn content and on increasing Ni content. The composition with higher Ni content has a higher degree of cation mixing. The synergistic effect of rhombohedral and monoclinic phases in Li rich Mn, Ni, and Fe based cathode is critical for stable electrochemical performance. The Li1.2Mn0.50Ni0.20Fe0.10O2 cathode showed the most stable cyclability performance (194 mAhg-1 first discharge capacity with 94 % capacity retention after 100 cycles at 0.3C rate) however, Li1.2Mn0.40Ni0.30Fe0.10O2 (220 mAhg-1 first discharge capacity with 57 % capacity retention) and Li1.2Mn0.55Ni0.15Fe0.10O2 (241 mAhg-1 first discharge capacity with 68 % capacity retention) cathodes showed higher 1st discharge capacity but poor cyclability under the same charge/discharge cycling.The XAS at Mn K-edge is used to explain the mechanism of Li2MnO3 activation for the improved electrochemical performance of Li rich Mn, Ni, and Fe oxide composite cathode, however Li2MnO3 contributed differently in different compositions. Synchrotron XRD and XAS measurements probed the lattice size expansion, which decreases the chemical potential of Li ions in the cathode on cycling leading to lower discharge voltage after cycling.
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Title: Non-invasive quantification of cancer drug targets: Mathematical models for paired-agent molecular imaging
Creator: Sadeghipour, Negar
Date: 2017
Description: Cancer is among the leading causes of death worldwide. Incidence of cancer is rising at a rate that is almost completely nullifying...
Show moreCancer is among the leading causes of death worldwide. Incidence of cancer is rising at a rate that is almost completely nullifying improvements in cancer treatment and the heterogeneity of advanced disease poses significant complications for the development of effective therapies. With more aggressive cancers tending to display abnormally high expression of signaling receptors associated cell proliferation - receptors that tend to be expressed at very low levels by healthy cells in adulthood - many new cancer-specific “molecular therapies” have been developed to target and block these pathways. However, not all cancers overexpress the same proliferation pathways, so many have proposed molecular imaging as a non-invasive means of identifying on a patient-by-patient basis, which specific targets may be overexpressed to tailor therapies to the individual (“precision medicine”). The primary goal of this thesis was to develop and validate some of the first non-invasive means of measuring drug-target concentrations prior to therapy and the first measures of drug-target occupancy during therapy to ultimately predict and monitor the efficacy of cancer molecular therapy. All work was founded on paired-agent molecular imaging protocols that employ co-administration of two imaging agents: one agent that is targeted to the biomolecule of interest (e.g. a cell surface signaling receptor that may be overexpressed by a cancer), and a second, “control” (“untargeted”) agent that is as chemically similar to the targeted agent as possible, but that does not bind to the biomolecule of interest. In all paired-agent imaging strategies, the signal from the control agent is used to account for delivery and nonspecific retention effects that can confound the relationship between the targeted imaging agent concentration in a region-of-interest (ROI) and the targeted biomolecule concentration in that ROI.
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Title: Polarization Induced by a Terahertz Electric Field on a Core-shell Particle
Creator: Li, Yanlin
Date: 2018
Description: Interactions of an electromagnetic wave with a sphere that is smaller than the wavelength can be accounted for by studying the dipole moments,...
Show moreInteractions of an electromagnetic wave with a sphere that is smaller than the wavelength can be accounted for by studying the dipole moments, which are the valid explanation for the scattering characteristics in the frequency region known as the Rayleigh region. The semiconductor nanoparticle with a core-shell structure describes a specific geometry yielding tunable plasmon resonance of the nanostructure. This is achieved by varying the thickness of the dielectric material shell layer on a semiconductor core. The polarization of core-shell sphere induced by a dynamic field is studied both analytically and numerically. Dielectric function is used for the description of the response of bound charges to an applied field, resulting in the electric polarization, which has been employed to explicate scattering and absorption properties of particles over the years. However, this traditional model has some limitations in accounting for some aspects of polarization when mobile charges are present. By coupling the transport equations of the charge carriers to the Maxwell’s equations, we can derive the electric field, charge and the total induced dipole moment of a nano-core-shell particle. Results of calculations accomplished for elementary structures such as plates and spheres represented the screening of the internal field while dispersion and absorptions effects are revealed by the complex dipole moments. And the results in static and quasi-static field are shown. Equivalent circuits for the core-shell structures are obtained from carrier transport consideration, which can be employed to guide the synthesis of new nanoparticles with heterogeneous internal structures to achieve novel polarization properties for sensing and terahertz circuitry applications.
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Title: STRUCTURAL DEFECT CONTROL TO IMPROVE SOLID-STATE REACTION AND ELECTROCHEMICAL PERFORMANCE OF NaCrO2 CATHODE FOR SODIUM-ION BATTERIES
Creator: Luo, Mei
Date: 2018
Description: NaCrO2 has been studied lately as a promising cathode material for Na-ion batteries. Consequently, this study was conducted to investigate how...
Show moreNaCrO2 has been studied lately as a promising cathode material for Na-ion batteries. Consequently, this study was conducted to investigate how high-energy ball milling before the high temperature reaction influences the synthesis reaction and electrochemical performance of NaCrO2 cathodes for Na-ion batteries. In-situ synchrotron X-ray diffractometry is employed for the first time to provide a comprehensive understanding of the critical reaction temperatures and reaction pathway. It is found that high-energy ball milling at room temperature can result in significant changes in the synthesis reaction of NaCrO2 when compared to reactants without high-energy ball milling. These changes include a decreased onset temperature for the formation of O3-NaCrO2, an increased reaction kinetics, an alternation of the reaction pathway, and a complete reaction at 900℃ to form thermally-stable O3-NaCrO2 phase. In contrast, without high-energy ball milling the reaction product at 900℃ is a highly impure NaCrO2 with a poor thermal stability. Equally important, it is found that mechanical activation enhances the bulk ionic conductivity as well as the conductivity at the interface of NaCrO2 particles; moreover, high-energy ball milling before reaction can lead to higher specific discharge capacities of NaCrO2 half cells and contribute to the best capacity retention over 50 cycles among all the reported NaCrO2 without coatings. All these improvements of NaCrO2 cathodes for Na-ion batteries are ascribed to the mechanical activation induced by high-energy ball milling before high temperature reaction.
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Title: Concurrency and Locality Aware GPGPU Thread Group Scheduling
Creator: Nosek, Janusz M
Date: 2018
Description: Graphics Processing Units (GPUs) once served a limited function for rending of graphics. With technological advances, these devices gained new...
Show moreGraphics Processing Units (GPUs) once served a limited function for rending of graphics. With technological advances, these devices gained new purposes beyond graphics. Most modern GPUs have exposed their APIs to allow processing of data beyond the display, thus leading to a revolution in computing where instructions and intensive tasks can be offloaded to these now General Purpose Graphical Processing Units (GPGPUs). Many compute and memory intensive tasks have utilized GPGPUs for acceleration and these devices are especially prevalent in the financial, pharmaceutical and automotive industries. As computing resources have increased exponentially, memory resources have not and now create a limiting factor known as the memory wall. GPUs have been designed as an application specific processing unit for the streaming data access patterns found in graphical applications. They are successful at their original purpose, but when extended to general purpose problems, they meet the same memory wall data access problem as their CPU counterparts; they can be more susceptible to the effects latency due to the locality and concurrency of instructions beside data. This thesis reviews the current GPGPU landscape, including the design of current scheduling systems, GPGPU architecture, as well as a way of computing and describing the memory access penalty with Concurrent Average Memory Access Time (C-AMAT). We will also demonstrate the current GPGPU landscape, including design of schedulers, simulators as well as how Concurrent Average Memory Access Time (C-AMAT) can be computed. We have devised a solution to manipulate the number of scheduled thread groups to allow a GPGPU’s processing units to match their current memory states defined by C-AMAT. Our solution results in the increase in IPC, the reduction in C-AMAT and decrease in memory misses. The solution also has different effects on different types of computing problems, with highest improvements achieved in compute intensive memory patterns with as much as a 12% improvement in the instructions per cycle and a 14% reduction in C-AMAT.
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Title: A Novel Non-parametric Density Estimation Approach to Measuring Muon Ionization Cooling and Reverse Emittance Exchange in the MICE Experiment
Creator: Mohayai, Tanaz Angelina
Date: 2018
Description: The Muon Ionization Cooling Experiment (MICE) located at Rutherford Appleton Laboratory in the U.K. has demonstrated muon ionization beam...
Show moreThe Muon Ionization Cooling Experiment (MICE) located at Rutherford Appleton Laboratory in the U.K. has demonstrated muon ionization beam cooling for the first time. A beam of muons in MICE is produced from high-energy proton beam collision with a fixed target, generating pions which in turn decay into muons. Pion-decay muons, thus, are tertiary particles and, as a result, occupy a large volume in position‒momentum phase space. To fit the muon beam into smaller and more cost-effective accelerating devices, muon beam phase‒space volume needs to be reduced (beam cooling). Ionization beam cooling, which before MICE has never been demonstrated experimentally for muons, is the only technique fast enough to be used for muons within their short lifetime. Ionization cooling occurs when muons traverse an absorbing material and lose momentum through ionization energy loss. The cooling effect in MICE is measured using two scintillating-fiber tracking detectors. These trackers, one upstream and one downstream of the absorber, reconstruct and measure the position and momentum coordinates of each muon. Given the precision MICE needed to demonstrate beam cooling, it is necessary to develop analysis tools that can account for any effects that may lead to inaccurate measurement of cooling, such as non‒linear effects in beam optics. Non‒parametric density estimation techniques, such as kernel density estimation (KDE), provide a basis for creating analysis tools that are robust against these effects, directly calculating the muon beam phase-space density and volume for demonstrating beam cooling. This thesis focuses on the application of KDE to the measurement of beam cooling in MICE. The KDE technique is validated using known distributions and is applied to simulated and experimental MICE data corresponding to the various magnet, optics, and absorber configurations. Using the KDE technique, muon beam cooling in the four‒dimensional transverse phase space, as well as reverse emittance exchange using MICE data have been demonstrated.
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Title: COMMUNICATION-BASED DISTRIBUTED CONTROL IN MICROGRIDS AND NETWORKED MICROGRIDS
Creator: Zhou, Quan
Date: 2019
Description: Microgrids representing localized small-scale power systems are capable of operating as self-controlled entities, which cluster and manage...
Show moreMicrogrids representing localized small-scale power systems are capable of operating as self-controlled entities, which cluster and manage distributed energy resources (DERs) and other smart devices within a defined electrical boundary. By utilizing locally available resources, microgrids reduce their dependencies on the utility grid, which provide more reliable, resilient, and economic power services to local customers. Geographically close microgrids can be connected for forming a networked microgrid system, which provides additional operational flexibility and further enhances the system reliability and resilience by sharing available DERs.Considering variable and controllable characteristics of DERs, locally available DERs need to be appropriately coordinated and controlled to respond to changing loads. The proliferation of microgrids will make it inevitable to rely on communication systems among microgrids for realizing the coordinated control of participating DERs in networked microgrid systems. The networked microgrid system is considered as a cyber-physical system (CPS) which requires sophisticated network technologies to cope with the massive adaption of communication, computation and control devices. Conventionally, a networked system has been managed by a centralized master controller, which processes the data collected from participating DERs and sends operational set points to each participant.Compared with the centralized control strategies, distributed control is more advantageous for connecting participating DERs. The connectivity of distributed control system (i.e., meshed network) is higher than that of a centralized structure (i.e., star network), in particular when critical circumstances are encountered in which some of the network connections are lost. Also, the distributed control system enables parallel data processing and control, which speeds up the networked system response to variable DERs and loads and promote economic merits. The communication-based distributed control strategies have proven to demonstrate higher reliability, resilience, and scalability while possessing lower implementation costs as compared with centralized control strategies.We have proposed several communication-based distributed control strategies for realizing the coordinated operation of participating microgrids and DERs, which can be applied to achieve various operational objectives, including proportional active power sharing, DER plug-and-play capability, seamless microgrid islanding, and resynchronization operations, and optimal economic operations. The benefits and challenges of communication-based distributed control strategies in networked microgrid systems are discussed and addressed in our work. Extensive case studies have been conducted in this thesis to validate the effectiveness of the proposed communication-based distributed controller design.
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Title: Scalable Non-Intrusive Load Monitoring
Creator: Zhuang, Mengmeng
Date: 2019
Description: Load Monitoring (LM) is a fundamental step to implement sustainable energy conservation. LM includes Intrusive LM (ILM) and Non-Intrusive LM ...
Show moreLoad Monitoring (LM) is a fundamental step to implement sustainable energy conservation. LM includes Intrusive LM (ILM) and Non-Intrusive LM (NILM). Real time feedback and informed advice to customers obtained from refined energy consumption can greatly improve energy efficiency towards sustainable energy conservation. Compared with intrusive approaches, non-intrusive approaches enjoy low cost, easy installation, and promising scalable commercialization potentials via elaborated data obtained from NILM. However, large-scale NILM deployments are facing challenges mainly including theoretical research and innovative applications. For theoretical research, there is still no generalized model to distinguish multiple-mode appliances, similar, or unknown appliances, and there is still no universal performance metrics to evaluate various NILM algorithms, especially for some unsupervised algorithms. For innovative applications, cost and user engagement are the two most important factors to limit the scalability of NILM. Scalable NILM refers to load disaggregation model that can be generalized and that has various application scenarios in a large-scale deployment. With the main objective of achieving scalable NILM, we focus on a semi-supervised generalized load disaggregation model and innovative applications including Proactive Demand Response (PDR) and energy information recommendation for enabling action towards sustainable energy conservation. Furthermore, in order to achieve sustainable energy conservation, we develop scalable NILM system and propose a user-centered comprehensive application platform Energy (ABC)2 to seek solutions from technology aspect and user engagement. On one hand, we propose an innovative virtual closed loop control concept model with human behaviors as virtual feedback controller and apply Deep Reinforcement Learning (DRL) approaches into DR decision management and personalized energy aware recommendation towards sustainable energy conservation. On the other hand, we develop and implement NILM deployment in China and propose an innovative idea on user engagement and data sharing solution business model, namely Energy Data Sharing Platform (EDSP), and design a scheme to strengthen the scalability of NILM towards a sustainable energy future.
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