339 research outputs found
“What Was Once A Rushing Torrent, Has Become A Broad River!”:Reflections on violation of socio-ecological justice in Orijit Sen's River of Stories and Sarnath Banerjee's All Quiet in Vikaspuri
No full textGraphic narratives such as Orijit Sen's River of Stories and Sarnath Banerjee's All Quiet in Vikaspuri present real, imaginary, and mythical rivers as sites of neoliberal hydro-politics and critique the extractivist modes of “developmentalism” that deprive riverine ecology and communities by integrating the rivers into the capitalist market economy. Sen's River of Stories, based on the Narmada Bachao Andolan, focuses on the government's forceful acquisition of the land of the tribal communities of Ballanpur village for the Rewasagar mega-dam project. Sen's panels portray the consequent displacement of the tribal people and massive ecological devastation. Sen presents the sacredness of the River Rewa in the tribal cosmology narrated by the tribal singer Malgu as contrary to the utilitarian developmentalist ideology that views the river as only a reservoir of hydrological energy. On the other hand, Banerjee's hydro-dystopia focuses on a plumber's voyage of excavating the mythical river Saraswati to solve the ongoing “water wars” of Vikaspuri (Delhi). Banerjee foregrounds country-wide “short-termist” projects as responsible for water pollution and scarcity. This chapter employs a postcolonial ecocritical perspective to argue that Sen and Banerjee's graphic river fictions employ verbal–visual mediums of image–texts and comic journalism to critique developmentalist practices connected to the capitalistic perception of the environment that victimise the “ecosystem people” who depend on the natural environment for sustenance, and advocate for socio-ecological justice within the framework of “environmentalism of the poor.
Modeling of mechanical energy dissipation of low-dimensional resonators
No full textNanoelectromechanical systems (NEMS) made from low-dimensional materials based on carbon, transition metal dichalcogenides, and their combinations have opened up new possibilities in high-precision sensing, signal processing, and studies of fundamental physical phenomena. In the heart of the NEMS is a vibrating mechanical element, known as the resonator. The performance of the NEMS critically depends on the mechanical energy dissipated by the resonator. Studies on dissipation are important because an understanding of the loss mechanisms can suggest ways to mitigate it. In most practical scenarios, the resonators suffer from intrinsic dissipation mediated by its inherent atomic thermal motions or phonons and extrinsic dissipation due to a fluid environment. In this context, low-dimensional resonators need special attention because the dissipation cannot be explained using the existing continuum theories. Due to atomic thickness, sub-micron dimension, and mega- to gigahertz frequencies of these resonators, nano-scale physical processes start becoming important. Most macroscale models do not account for these physical processes, warranting the current line of research. In this thesis, we use atomistic simulations and statistical-mechanical theories to understand and formulate the nanoscale physical processes, and integrate them to develop a multiscale model for dissipation.
In the first part of the thesis, we explore fluid coupled resonator systems with an objective to understand different dissipative processes such as phonon-mediated intrinsic dissipation, viscous damping by the fluid, and the cross-interaction between each source of dissipation, i.e., phonons and fluid at a regime of gigahertz frequency, and nanometer length scale. First, we consider a single-walled carbon nanotube (SWCNT) resonator with confined Argon and driven under axial mode. The intrinsic dissipation in the SWCNT at gigahertz frequencies could be explained by Akhiezer theory. We show that intrinsic dissipation, which is conventionally treated as an independent process, can be modified by fluid interactions due to the phonon- fluid coupling. We show that an important consequence of this phonon-fluid coupling is the counter-intuitive inverse scaling of net dissipation with fluid density at low excitation frequencies. Next, we consider flexural vibration of the SWCNT with interior and exterior Argon. When compared with the fluid exterior case, the SWCNT with confined fluid shows a low and anomalous scaling of dissipation with fluid density. We systematically analyzed the sources of dissipation and found that the fluid contributed to the anomalous scaling. A formulation of the fluid response during the flexural motion revealed a viscoelastic nature of the fluid under nano-confinement, which explains the anomalous scaling. Further, we use the framework for dissipation analysis to examine the effect of thermal motion of the resonator atoms on fluid dissipation, demonstrate a frequency dependent dissipation scaling with density, and comment on the mechanism of intrinsic dissipation during flexural resonance of an SWCNT.
In the second part, we develop a multiscale framework to model intrinsic dissipation in two-dimensional (2D) microresonators. The work aims to reveal the fundamental limit of dissipation and enable looking at the isolated effect of various parameters over a wide range, both of which are inaccessible in experiments. The damping of the flexural mode of a 2D microresonator takes place due to the nonlinear coupling with other thermally excited elastic modes. A particular flexural mode can couple with another flexural mode with a wavelength ranging from the size of the resonator to that of the lattice spacing. However, the coupling at these disparate length scales needs different modeling approaches. In the multiscale framework, we model the continuum-scale modes as Langevin oscillators (LOs) with nonlinear coupling terms. The parameters of the LOs are computed using continuum mechanical analysis and atomistic simulations. Using this framework, we study the effect of various parameters of interest such as vibration amplitude, resonator size, temperature, and pre-strain in the case of graphene resonators and draw some important conclusions towards engineering high-quality 2D resonators.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-05-01The student, Subhadeep De, accepted the attached license on 2019-02-13 at 12:01.The student, Subhadeep De, submitted this Dissertation for approval on 2019-02-13 at 12:51.This Dissertation was approved for publication on 2019-02-15 at 11:34.DSpace SAF Submission Ingestion Package generated from Vireo submission #13388 on 2019-08-22 at 15:04:21Made available in DSpace on 2019-08-23T20:28:06Z (GMT). No. of bitstreams: 3
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Previous issue date: 2019-02-15Embargo set by: Seth Robbins for item 112082
Lift date: 2021-08-23T20:28:11Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112082
Lift date: 2021-08-23T20:29:33Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112082
Lift date: 2021-08-23T20:36:18Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 112082 on 2021-08-24T09:15:34Z
Phenazines as chemosensors of solution analytes and as sensitizers in organic photovoltaics
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Porphyrin N-Oxidations and beta,beta\u27-Bond Modifications
No full textThis thesis begins with an introduction to porphyrins and chlorins, their natural and synthetic analogues, the biological roles of porphyrins, followed by the synthesis of porphyrins and their derivatization towards chlorins. The introduction also deals with the structural analysis of porphyrins and a classification of their optical spectra, followed by a brief outline of the applications of porphyrins and chlorins. Subsequently, there is a discussion on the various types of porphyrins present with substitution in the porphyrin core as well as in the periphery. The structure, synthesis and spectroscopic properties of core substituted and peripherally modified porphyrins are also discussed.^ A detailed description of porphyrin and chlorin N-oxides is carried out in the Results and Discussion Chapter 1, describing their synthesis, reactivity, crystal structure and a comparison of their optical spectra. A possible biological application is outlined.^ An exploration of the reactivity of the porphyrin α-position and synthesis of a pyrrole-ring contracted chlorin is discussed in Chapter 2. ^ In Results and Discussion Chapter 3, the synthesis, spectroscopy and stereochemical assignment of helimeric porphyrinoids with a morpholino subunit are discussed.^ In Results and Discussion Chapter 4, the synthesis of trans-diolchlorins and their manipulation leading up to the synthesis of pyrrole ring homologated porphyrins is discussed.
Porphyrin N-Oxidations and beta,beta\u27-Bond Modifications
No full textThis thesis begins with an introduction to porphyrins and chlorins, their natural and synthetic analogues, the biological roles of porphyrins, followed by the synthesis of porphyrins and their derivatization towards chlorins. The introduction also deals with the structural analysis of porphyrins and a classification of their optical spectra, followed by a brief outline of the applications of porphyrins and chlorins. Subsequently, there is a discussion on the various types of porphyrins present with substitution in the porphyrin core as well as in the periphery. The structure, synthesis and spectroscopic properties of core substituted and peripherally modified porphyrins are also discussed.^ A detailed description of porphyrin and chlorin N-oxides is carried out in the Results and Discussion Chapter 1, describing their synthesis, reactivity, crystal structure and a comparison of their optical spectra. A possible biological application is outlined.^ An exploration of the reactivity of the porphyrin α-position and synthesis of a pyrrole-ring contracted chlorin is discussed in Chapter 2. ^ In Results and Discussion Chapter 3, the synthesis, spectroscopy and stereochemical assignment of helimeric porphyrinoids with a morpholino subunit are discussed.^ In Results and Discussion Chapter 4, the synthesis of trans-diolchlorins and their manipulation leading up to the synthesis of pyrrole ring homologated porphyrins is discussed.
Solitary intracavitory cardiac metastasis
No full textMetastatic cardiac tumors are more common than the primary ones and they most commonly involve the pericardium or myocardium. Very rarely they may show partial or total intracavitory growth. Ours is one such case of solitary intracavitory cardiac metastasis in a patient with adenocarcinoma of the right lung who presented with hemoptysis and palpitation. Echocardiography and histopathological study clinched the diagnosis
Polysaccharide installed lipid nanoparticles in targeted antituberculosis drug delivery applications
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