http://hdl.handle.net/123456789/269 2023-05-16T01:38:02Z http://hdl.handle.net/123456789/2060 Title: Quantification of open waste burning emissions over the indian subcontinent: Authors: Sharma, Gaurav; Sinha, Baerbel Abstract: India struggles with frequent exceedances of the ambient air quality standard for particulate matter and benzene. In the past two decades, India has made considerable progress in tackling indoor air pollution, by phasing out kerosene lamps, and pushing biofuel using households towards Liquefied Petroleum Gas (LPG) usage yet air quality has not improved adequately. Open waste burning is a ubiquitous but often neglected air pollution source which can be observed happening in our surroundings on a daily basis. Waste generation and open burning of waste increases as a result of rapid economic development. Waste disposal and management services typically struggle to keep pace with exponential increase in waste generation when the economy of a nation grows rapidly. At the same time, greater the wealth or prosperity levels leads to more demand for a clean environment from citizens. At a certain point in time when the mismatching between waste generation and waste disposal service quality becomes too large, open burning of any unwanted material becomes socially acceptable. This process happened in the past in several developed nations and is now happening in developing nations. Back yard burning was considering to be biggest source of dioxin in the USA in early 2000s. however, these are now better regulated and the emissions have reduced. Developing nations, on the other hand, still struggle with a mismatch between waste generation and waste management capabilities and consequently suffer from air pollution due to open waste burning. Yet, the official agencies often deny open waste burning exists, and major atmospheric emission inventories such as EDGAR and REAS fail to include this source. Accurate emission inventories serve as critical inputs for air quality and climate models, but are poorly constrained over India. In first part of my thesis work I present a new municipal open waste burning emission inventory from India (OWBEII), at a resolution of 0.1° x 0.1°. Out of the 216 (201-232) Tgy -1 of waste produced in the year 2015, 68 (45-105) Tgy -1 wasburned in the open. To determine emissions from waste burning, emission factors of 59 non- methane volatile organic compounds (NMVOCs), CH 4 , CO 2 , CO and NOx were measured from garbage fires in a rural and urban site in India. The NMVOC emissions from open waste burning of 1.4-2 Tgy -1 increase India’s total anthropogenic NMVOC budget by 8-12%, while Black Carbon (BC) emissions (40-110 Ggy -1 ) increase the total anthropogenic BC emissions by 8-12%. Open waste burning in India emits 3-7 Tgy -1 of CO and 58-130 Tgy -1 of CO 2 . Emissions increase the total anthropogenic CO and CO 2 in the MIX-Asia inventory by 4-11% and 2-6%, respectively. My study highlights that open waste burning may impact atmospheric OH reactivity and ozone formation rates downwind of urban centers through the emission of other highly reactive compounds such as acetaldehyde (20-320 Ggy -1 ), propene (50-170 Ggy - 1 ) and ethene (50-190 Ggy -1 ) and is source of carcinogenic benzene (30-280 Ggy -1 ). In the second part of my thesis I develop waste generation projections for the 21st century. Waste generation projections for emerging economies like India are highly uncertain. I present waste generation and open waste burning projections for India based on a new approach which considers the projected future income inequality within the country while calculating future waste generation. I evaluated the population and income projections in the shared socio- economic pathways (SSPs) database against recent census data to reduce the uncertainty of projections. I found that for India the SSP3 and SSP2 narrative are no longer consistent with observed fertility trends and limit the projection to the SSP 1, 4 and 5 scenarios. SSP5, the scenario with the fastest economic growth, results in the highest projected waste generation of 272 Tgy -1 and 400 Tgy -1 by 2030 and 2050, respectively. Despite differences in population and income structure the SSP1 and SSP4 narratives result in very similar total waste generation estimates of 252±2 and 333±16 Tgy -1 , but different regional trends for the year 2030 and 2050, respectively. I presented assumptions about technological progress, and policies that are broadly in line with the SSP narratives and explore the differences in open waste burning emissions that results from different levels of commitment to a circular economy. I found that a strong commitment to convert biodegradable waste into compressed biogas can bring the country onto a SSP1 trajectory and can reduce open waste burning emissions to one third of what they would be with a business-as-usual approach to waste management. The move will not only help to mitigate open waste burning emissions and landfill fires, it will also help to shift the economy towards low carbon residential fuel choices and a cleaner transport sector. In the third part of the thesis, I calculated past trends in residential fuel consumption and extrapolated them into the future, to explore changes in the contribution of different sectorstowards India’s largest air pollution problem. I found that residential fuel usage is still the largest air pollution source, and that the <10% households using cow dung as cooking fuel contribute ~50% of the residential sector PM 2.5 emissions. I also found that if current trends persist, residential biofuel usage in India is likely to be phased out by 2035. India’s renewable energy policies are likely to reduce emissions in the heat and electricity sector, while its recent biogas initiatives are likely to reduce emission from manufacturing industries that currently use solid biomass as fuel. PM 2.5 emissions from open waste burning, on the other hand, hardly changed in the decade from 2010 to 2020 and will not reduce unless we significantly invest into upgrading waste management systems. I conclude that without strong policies to promote recycling and upcycling of non-biodegradable waste, and the conversion of biodegradable waste to biogas, open waste burning is likely to become India’s largest source of air pollution by 2035. While my study is limited to India, my findings are of relevance for other countries in the global South suffering from similar waste management challenges. 2022-05-01T00:00:00Z http://hdl.handle.net/123456789/2059 Title: Quantum thermodynamic resources and bounds on the performance of quantum otto engines Authors: Mehta, Venu; Johal, Ramandeep Singh Abstract: Quantum thermodynamic resources and bounds on the performance of quantum Otto engines Abstract Quantum thermodynamics is an emerging research field aiming to close the gap between the microscopic world of quantum mechanics and the macro- scopic world of classical thermodynamics by establishing a novel thermo- dynamic framework that incorporates and exploits non-classical resources of quantum discreteness, correlations, entanglement and so on. To achieve this goal, quantum analogues of classical heat engines serve as test beds to demonstrate extensions of thermodynamic ideas into the quantum realm. Multifarious proposals for quantum heat engines or refrigerators have been proposed. Amongst these, the study of simple, coupled quantum systems yield important insights into the role of quantum interactions in enhancing the performance of model thermal machines. One of the major issues being addressed in these models is: What are the thermodynamic constraints and bounds on the performance of these quantum thermal machines? In the present work, quantum Otto engines (QOEs), with quantum spins as the working substance, have been investigated. An Otto cycle is widely stud- ied in literature, because the contributions of heat and work can be clearly separated into different steps during the heat cycle. We begin by considering 1two coupled, effectively two-level systems—each with a degenerate excited state, and then generalize it to the case of two coupled spins of arbitrary magnitudes. For a quasi-static QOE, we prove that level degeneracy can act as a thermodynamic resource, helping to extract a larger amount of work than in the non-degenerate case, either without coupling or in the presence of coupling. We compare our analysis with earlier studies on the role of level degeneracy in finite-time models of thermal machines. Further, by carefully making use of the information from the energy spectrum of the working medium, we look for conditions to better the performance of the coupled system over its uncoupled counterpart using heuristics based approach. An upper bound for the efficiency of the Otto cycle has thus been calculated in these models, setting new benchmarks for Otto efficiency that is tighter than Carnot bound. We also analyze the performance of the engine using the notion of complete Otto cycles inherent in an average cycle and highlight its utility as a heuristic. 2021-12-01T00:00:00Z http://hdl.handle.net/123456789/2039 Title: Probing the dynamics and binding properties of fluorinated drugs, ionic liquides and biomolecules via NMR relaxation and diffusion experiments Authors: Sharma, Rakesh; Dorai, Kavita Abstract: NMR has applications in several different fields such as drug discovery and design, structure and dynamics of biomolecules, drug delivery, medicine, material science, environmental science and metabolomics. One of the most important applications of NMR is to study drug dynamics and drug interactions with different molecules includ- ing proteins. This thesis is an attempt to study drug behavior in different environments, and drug interactions and dynamics by using NMR relaxation and diffusion experi- ments. Further, NMR spectroscopy is among the main analytical techniques that can be used for metabolomics studies as it can accurately quantify and detect metabolites in complex mixtures, with minimal sample preparation. The fast profiling of metabolite mixtures by using 2D NMR techniques and their chemometric analysis is a problem of current interest and several attempts have been made in recent years in this direc- tion. We have utilized a fast 2D heteronuclear correlation NMR experiment to perform full chemometric analysis of metabolites in a variety of model systems. Results were compared with standard 2D NMR correlation experiments and reported in the thesis. The contents of the thesis have been divided into six chapters whose brief account is sketched below: Chapter 1 The first chapter of the thesis begins with an introduction to the basic phenomenon of NMR, the various NMR interactions such as chemical shift and dipolar interactions. Fourier transform method is described to process digitized NMR data and the basic hardware components of an NMR spectrometer are described, including the supercon- ducting magnet, rf transmitter, probe, receiver, and workstation for signal acquisition and data processing. Nuclear spin relaxation including cross-correlated spin relaxation v0. Abstract is taken up next, followed by a basic overview of quantum chemical calculations of the chemical shift anisotropy tensor as well as diffusion NMR studies. The importance of 19 F NMR and its utility in drug delivery and analysis is discussed. Two-dimensional NMR methods for metabolomics studies are also discussed at the end of this chapter. Chapter 2 Due to its extensive antitumor activity and synergism with other anticancer medica- tions, 5-Fluorouracil (5FU) has become a prominent anticancer agent that has been used to treat numerous types of malignancies since its inception several decades ago. It is a major agent as a first line anti-cancer drug, commonly used to treat colorectal, gastrointestinal, and breast cancer. However many variables such as its tendency for inducing drug resistance in tumor cells, fast rate of metabolism in the body, cytotoxic- ity, a short biological half-life, and non-uniform oral adsorption restrict the efficacy of 5FU. Encapsulating 5FU in a host system with a long-term drug release could reduce the number of times the medicine needs to be given, as well as the negative side effects, and make oral administration possible. While there are several delivery systems that have been reported for 5FU, the efficacy of the drug and its delivery is affected by the solubility of drug in the medium as well as the local environment around the drug. In this chapter we describe the measurement of the fluorine NMR relaxation parameters of 5FU in different kinds of molecular environments, namely in D 2 O, in an ionic liquid, in a lipid bilayer and in a triblock copolymer. Due to different local environments, the fluorine cross-correlated spin relaxation rates obtained via measurement of differential line relaxation are significantly different for each environment. The longitudinal relax- ation rates and diffusion coefficients were also computed using NMR relaxation and diffusion experiments. The change in rotational correlation time τ c was also calculated and the effect of the environment on rotation and dynamics of the drug was quantified. Chapter 3 Drug delivery systems (DDS), which include particulate carriers made mostly of lipids and/or polymers, and their accompanying treatments can improve many of the pharma- cological features of conventional medications. Various materials such as liposomes, lipids, carbon nanotubes, and polymers have been utilized as nano-sized DDS. Due to vitheir versatility, polymers have been extensively researched for a variety of carriers, including micelles, nanogels, vesicles, and nanoparticles. Polymers have several ad- vantageous properties including ease of preparation, controlled release of drugs and high drug loading capacity. In this chapter, triblock copolymers in different polymer- ization states were studied for their effect on 5F-Tryptophan. 5F-Tryptophan is used as a model system and its interactions with triblock copolymers F127 and P123 stud- ied at different concentrations. The attenuation of signal amplitude in the pulse field gradient diffusion for 19 F spin of 5F-Tryptophan was studied and it was concluded that different polymerization states of both the polymers show significant differences in signal attenuation at different concentrations. The effect was also studied at three dif- ferent temperatures. Longitudinal spin-lattice relaxation rates and transverse spin-spin relaxation rates were also measured for all the samples. Chapter 4 The usage of ionic liquids (ILs) as a solvent has grown sharply over the last twenty years due to their unique properties and potential uses as novel reaction media. ILs are green alternatives to standard organic solvents because of their low volatility, non- flammability, and greater stability when exposed to thermal and chemical stressors. ILs can be highly flexible as a result of tuning their cations and anions as well as their substituents. Several studies have showed the interaction of ILs with drugs and demon- strated their utility as potential drug delivery systems. In this chapter, we quantified the interaction of an IL with 5-fluorouracil, which has been extensively used as an anti- tumor drug. Relaxation and diffusion NMR experiments can provide valuable insights into internal molecular dynamics and the overall hydrodynamic behavior of ILs as sol- vent media. We studied the interaction of 5-fluorouracil with the ionic liquid 1-butyl-3- methylimidazolium bromide (BMIMBr) via NMR relaxation experiments and quan- tum chemical calculations. It has been shown in previous studies that 5-fluorouracil is effective for treatment of skin cancer when it is dissolved in C4MIMBr as compared to water. Also, in the ionic liquid, the drug solubility increases 2.5 times as compared to water. In order to understand the dynamics of 5-Fluorouracil in C4MIMBr, we per- formed quantum chemistry calculations using the Gaussian package and were able to delineate a 5-fluorouracil-C4MIMBr interaction model. We have optimized and ar- vii0. Abstract ranged the stability order of structures and preferred interaction sites on the basis of energy value. It was found that the fluorine site in 5-fluorouracil is the third most preferable site for interaction of ionic liquid. These interaction sites were corrobo- rated via NMR relaxation rates measurements. Five samples at Drug:IL concentration ratios were prepared. Interaction sites were identified from longitudinal spin-lattice and transverse spin-spin relaxation rates as well as from diffusion coefficient measure- ments. The theoretical and experimental results were found to be in good agreement. Chapter 5 Due to ease of sample preparation and accurate metabolite identification and quan- tification, NMR spectroscopy is an important tool for metabolomics. 1D 1 H NMR spectra can be acquired easily with high sensitivity in few minutes, however due to the presence of several metabolites with severely overlapping peaks which are hard to differentiate and identify, 1D NMR has limited use. Two-dimensional (2D) NMR spec- troscopy has several advantages over 1D NMR and can provide detailed information about molecular structure via different correlation maps between atoms. However due to long experimental acquisition times, no direct quantification of peaks, pulse imper- fections and other experimental artifacts, 2D NMR has not been extensively used for metabolomics studies. In this chapter we performed chemometric analysis of green tea and black tea samples by using a fast 2D NMR pulse sequence to reduce experimental time. The ASAP-HSQC scheme (Acceleration by Sharing Adjacent Polarization Het- eronuclear Single Quantum Correlation spectroscopy) was used to record 2D 13 C– 1 H correlation spectra. The results in this chapter demonstrate the merits of directly using 2D NMR spectral peak intensities instead of the more traditional 1D 1 H NMR peaks as inputs for multivariate statistical analysis. Metabolites were identified solely from the 2D NMR spectra, and the NMR analysis was combined with multivariate pattern recognition to identify metabolites that contribute significantly to the metabolic differ- ences between green tea and black tea. The HSQC 0 approach was used to accurately quantify 2D cross-peak intensities. 2D NMR spectra were processed in MATLAB. The 2D ASAP-HSQC experiment is able to obtain the same two-dimensional car- bon–proton correlation information as the standard 2D HSQC experiment, in a frac- tion of the time as taken by normal HSQC. The results of performing multivariate data viiianalysis on 2D NMR datasets was compared with those obtained by using 1D NMR datasets and a good agreement was found between the two methods. Also, a multi- variate analysis was performed to identify metabolites that vary in concentration in Bougainvillea plant leaves collected at two different times during the day. For this model, there was no prior information about metabolites identified from 1D 1 H NMR data, and 2D NMR data alone was used to perform the entire analysis and identify the significant metabolites. Chapter 6 This chapter provides some general remarks on the problems covered in the thesis. Possible future applications of the projects in this thesis and the new avenues of re- search they open up are described. The overall contribution of this thesis in the context of drug delivery and 2D NMR-based metabolomics is summarized. ix 2022-02-01T00:00:00Z http://hdl.handle.net/123456789/1855 Title: Skyrmions and antiskyrmions in spin-orbit modified double exchange models Authors: Kathyat, Deepak Singh Abstract: It has been understood that the conventional electronics based devices will not be able to meet the ever increasing requirements for data storage and processing of the modern world. Among others, the idea of utilizing the spin degree of freedom asso- ciated with electrons has been considered as a potential alternative. This has given rise to a new research field, popularly known as spintronics, wherein electron’s spin is used as the carrier of information for device functionalities. While it is not easy to detect and utilize spin of a single electron in materials containing a large number of them, certain magnetic configurations show a desired stability and possible con- trol via external electric or magnetic field. Therefore, search for magnetic materials supporting certain stable magnetic textures has become a key theme of research in recent years. Topologically protected magnetic textures, such as skyrmions and anti- skyrmions are of special importance due to their stability. Such textures have been discovered in chiral magnets and in thin films of a variety of magnetic metals. The fundamental physics associated with formation of magnetic skyrmions has fascinated researchers since the discovery of these topological textures. The current approach to understand these intriguing textures is via spin models consisting of Dzyaloshinskii-Moriya (DM) interactions or frustrating long range interactions. In this thesis, we present a microscopic mechanism for skyrmion and antiskyrmion formation in metals that emerges from electronic itinerancy. We derive and study a microscopic spin Hamiltonian on a lattice for double exchange metals modified by the Rashba and Dresselhaus spin orbit coupling (SOC). In our model, anisotropic interactions of the Dzyaloshinskii-Moriya (DM) and pseudo dipolar form emerge naturally in addition to the standard isotropic term. We present phase diagram of the effective spin Hamilto- nian which has veryinteresting ground states like classical spin liquid state using large scale Monte Carlo simulations. We show that in presence of Zeeman field the mecha- nism we propose not only provides an accurate microscopic understanding of existence of skyrmions, but also explains key features in small angle neutron scattering (SANS) and Lorentz transmission electron microscopy (LTEM) data on thin films of MnSi- type B20 metals and transition metals and their alloys. We identify hexagonal andsquare lattice arrangements of skyrmions in two different regimes of the parameter space. Sparse skyrmions emerge at finite temperatures as excitations of the ferromagnetic phase. Further, the skyrmion states are characterized as topological metals via explicit calculations of Bott index and Hall conductivity. Local density of states (LDOS) display characteristic oscillations arising from a combination of confinement effect and gauge-field induced Landau level physics. These unique features serve as testable predictions for the presence of the new mechanism of skyrmion formation in real materials. The discovery of a new mechanism based on two celebrated physics concepts not only fills a major conceptual void in the current understanding of skyrmions and antiskyrmions in metals, but also opens a new route for tuning the size, density and stability of skyrmions in magnetic metals. We also emphasize the importance of a consistent treatment of spin-orbit coupling for calculating electronic properties of metals hosting unconventional magnetic textures such as skyrmions. Finally, we provide a clear understanding of how Neel-type skyrmions, Bloch-type skyrmions and the corresponding antiskyrmions are related with one another within a simple lattice model. We also emphasize the role played by electron itineracy in decid- ing the type of skyrmion textures in a metal. These features are completely missed in a spin-only model written without reference to a starting microscopic model. 2021-07-01T00:00:00Z