Recursos de colección

ETD at Indian Institute of Science (3.599 recursos)

Repository of Theses and Dissertations of Indian Institute of Science, Bangalore, India. The repository has been developed to capture, disseminate and preserve research theses of Indian Institute of Science.

Chemical Engineering (chemeng)

Mostrando recursos 1 - 20 de 55

  1. Unraveling the Evolutionary Advantages of Crosstalk Between Two-Component Signalling Systems of M tuberculosis

    Bharadwaj, Vemparala
    M. tuberculosis (Mtb) senses and responds to changes in its environment primar-ily through two-component signalling systems (TCSs). Each TCS contains a trans-membrane histidine kinase (HK ) protein and a cytoplasmic response regulator (RR) protein. HK detects a stimulus and gets phosphorylated. It then binds and transfers the phosphoryl group to the RR of the same TCS. Activated RR then triggers gene ex-pression, including upregulation of the HK and RR involved, eliciting responses that are essential for the bacterium to adapt. Though di erent TCSs detect distinct stimuli, the binding regions of the HK s and RRs share signi cant similarity....

  2. Multi-scale Modelling of Lamellar Mesophases

    Jaju, S J
    Surfactants are amphiphilic molecules which self-assemble at the interface in oil-water-surfactant mixtures such that the hydrophobic part, called tail, stays in oil and the remaining part, called head, resides in hydrophilic en-vironment. Depending upon concentration of individual components, these mixtures form several microphases, such as bilayers, micelles, columnar and lamellar phases. A lamellar phase, at equilibrium, is made up of alternat-ing layers of water and oil separated by surfactants, or of alternate layers of water and surfactant bilayers such that the hydrophilic heads are in contact with water. This equilibrium state is rarely achieved in macroscopic samples due to thermodynamic...

  3. Modelling How Refractoriness to Interferon Compromises Interferon-Free Treatment of Hepatitis C Virus Infection

    Venugopal, Vishnu
    Hepatitis C virus (HCV) infection globally affects 130-150 million people. It causes both acute and chronic infections. Due to the severe side effects and low success rates of interferon based treatments, which formed the standard treatment for HCV, the treatment paradigm shifted to direct acting antivirals (DAAs). DAAs have revolutionized the treatment of hepatitis C virus infection. Clinical trials with combinations of DAAs have recorded >90% response with shorter treatment durations and fewer side effects than earlier treatments involving IFN. Outside the controlled setting of a clinical trial, however, response rates with DAA combinations are much lower (<70%). DAAs can...

  4. Stochastic Models Suggest Guidelines for Protocols with Novel HIV-1 Interventions

    Gupta, Vipul
    The treatment of human immunodeficiency virus (HIV-1) infection faces the challenge of drug resistance. The high mutation rate of HIV-1 allows it to develop resistance against all available drugs. New mechanisms of intervention that do not succumb to failure through resistance are thus being explored. Mutagens that increase the viral mutation rate are a promising class of drugs. They can drive HIV-1 past a critical mutation rate, called the error threshold, and induce a catastrophic loss of genetic information. The treatment duration for a mutagen to drive HIV-1 beyond this error threshold is not yet estimated. We devise a detailed...

  5. Studies in Water Treatment : Defluoridation using Adsorption, Denitrification using a Microbial Fuel Cell, and Contaminant Removal using Solar Distillation

    Samrat, Maruvada Veera Venkata Naga
    This thesis includes both experimental and modelling studies on the treatment of drinking water. Three aspects were studied: (i) removal of fluoride (F– ) by adsorption, (ii) removal of fluoride and other contaminants by solar distillation, (iii) denitrification by a microbial fuel cell. The availability of potable water on earth is about 0.2% of the total available water. This very small quantity is polluted by anthropogenic and natural contaminants. Fluoride is a classic example of a natural contaminant, wherein the dissolution of F– bearing minerals causes the release of F– into the groundwater. Exposure to concentrations > 1 mg/L over ex-tended...

  6. Molecular Simulation Study of Electric Double Layer Capacitor With Aqueous Electrolytes

    Verma, Kaushal
    Electric double layer capacitors (EDLCs) are an important class of electrical energy storage devices which store energy in the form of electric double layers. The charging mechanism is highly reversible physical adsorption of ions into the porous electrodes, which empower these devices to show a remarkable power performance (15kW/kg) and greater life expectancy (> 1 million cycles). However, they store a small amount of energy (5Wh/kg) when compared with batteries. Optimization of the performance of EDLCs based on porous activated carbons is highly challenging due to complex charging process prevailing in the Nano pores of electrodes. Molecular simulations provide information...

  7. Modeling Human Immunodeficiency Virus Transmission and Infection

    Nagaraj, Pradeep
    HIV-1 is a global pandemic with about 39 million people infected. In India, 2.9 million people are infected and about 2 lakh new infections have been reported last year. To date, there is no cure for HIV/AIDS. Current treatment, which is associated with serious side effects, only delays the onset of AIDS and death. Thus, HIV/AIDS is responsible for a global health concern imposing significant healthcare costs, especially in low- and middle-income regions such as India and Africa, and a marked loss of quality of life to infected individuals. Understanding factors impacting vaccine design and drug development via mathematical modelling...

  8. Direct Numerical Simulations and Fluctuating Force Simulations of Turbulent Particle-gas Suspensions

    Tyagi, A
    Turbulent gas-particle suspensions are of great practical importance in many naturally phenomena, such as dust storms and snow avalanches, as well as in industrial applications such as fluidised, circulating bed reactors and pneumatic transport. Due to the difference in mass density of about three orders of magnitude between solids and gases, the mass loading is large, but the volume fraction of the particles is usually small. Since the length scale of these flows ranges from tens of centimeters to hundreds of meters, the Reynolds number based on the flow dimension and velocity is usually large. Due to this, these flows...

  9. Modeling and Experimental Investigations into Soluble Lead Redox Flow Battery : New Mechanisms

    Nandanwar, Mahendra N
    Continued emission of green house gases has energized research activity worldwide to develop efficient ways to harness renewal energy. The availability of large scale energy storage technologies is essential to make renewal energy a reliable source of energy. Redox flow batteries show potential in this direction. These batteries typically need expensive membranes which need replacement be-cause of fouling. The recently proposed soluble lead redox flow battery (SLRFB), in which lead ions deposit on electrodes in charge cycle and dissolve back in discharge cycle, can potentially cut down the cost of energy storage by eliminating membrane. A number of challenges need...

  10. Formation of Porous Metallic Nanostructures Electrocatalytic Studies on Self-Assembled Au@Pt Nanoparticulate Films, and SERS Activity of Inkjet Printed Silver Substrates

    Banerjee, Ipshita
    Porous, conductive metallic nanostructures are required in several fields, such as energy conversion, low-cost sensors etc. This thesis reports on the development of an electrocatalytically active and conductive membrane for use in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) and fabrication of low-cost substrates for Surface Enhanced Raman Spectroscopy (SERS). One of the main challenges facing large-scale deployment of PEMFCs currently is to fabricate a catalyst layer that minimizes platinum loading, maximizes eletrocatalytically active area, and maximizes tolerance to CO in the feed stream. Modeling the kinetics of platinum catalyzed half cell reactions occurring in a PEMFC using the kinetic theory...

  11. Monodisperse Gold Nanoparticles : Synthesis, Self-Assembly and Fabrication of Floating Gate Memory Devices

    Girish, M
    The emergence of novel electronic, optical and magnetic properties in ordered two-dimensional (2D) nanoparticle ensembles, due to collective dipolar interactions of surface plasmons or excitons or magnetic moments have motivated intense research efforts into fabricating functional nanostructure assemblies. Such functional assemblies (i.e., highly-integrated and addressable) have great potential in terms of device performance and cost benefits. Presently, there is a paradigm shift from lithography based top-down approaches to bottom-up approaches that use self-assembly to engineer addressable architectures from nanoscale building blocks. The objective of this dissertation was to develop appropriate processing tools that can overcome the common challenges faced in...

  12. Alternative Mechanisms for Size Control in Synthesis of Nanoparticles - Population Balance Modelling and Experimental Studies

    Perala, Siva Rama Krishna
    The extensive growth of nanotechnology has necessitated the development of economical and robust methods for large scale production of nanomaterials. It requires detailed quantitative understanding of lab-scale processes to enable effective scale-up and development of new contacting strategies for their controlled synthesis. In this thesis, attempts are made in both the directions using experimental and modelling approaches for synthesis of different nanoparticles. The two-phase Brust--Schiffrin protocol for the synthesis of gold nanoparticles was investigated first. The mechanism of transfer of reactants from aqueous to organic phase using phase transfer catalyst (PTC) was investigated using the measurement of interfacial tension, viscosity, SLS, SAXS, 1H NMR,...

  13. Testing the Hypothesis of Quorum Sensing in Vibrio fischeri : Luminescence, Motility, and Biofilm

    Srinivasa Sandeep, S
    The individual behaviour of prokaryotic organisms such as bacteria often gives rise to complexity that is commonly associated with multicellular behaviour. The transition from unicellular to multicellular behaviour occurs in response to chemical signals, called autoinducers, which bacteria generate and receive internally within a given population. These autoinducers control the gene expression necessary for the emergence of group-behaviour-phenotype. This phenomenon is called quorum sensing (QS). An example of the quorum sensing control of gene regulation has been the luminescence (lux) operon in Vibrio fischeri. The luxI and ainS quorum signalling systems work in conjunction to regulate luminescence in V. fischeri....

  14. Crystal Nucleation in Binary Hard Sphere Mixtures

    Rao, G Srinivasa
    Homogeneous crystal nucleation in binary hard sphere mixtures is an active area of research for last two decades. Although Classical nucleation theory (CNT) gives a qualitative picture, it fails at high super saturations because of the following reasons. CNT assumes that the cluster formed is spherical in shape, its properties can be modeled using the bulk properties of the stable solid phase and the interfacial free energy γ between the nucleus and the surrounding metastable fluid is equal to the planar surface tension between two phases at coexistence. These assumptions get increasingly tenuous at higher degrees of super saturations where...

  15. Inactivation of Microorganisms by Photocatalysis

    Sontakke Sharad, M
    Photocatalysis is an advanced oxidation process, which has shown to possess an enhanced capability to remove a wide range of contaminants. It involves the use of a semiconductor photocatalyst and a photon source. Photocatalysis has several advantages such as mild reaction conditions like ambient temperature and pressure, good control over the reaction and faster reaction kinetics. Semiconductor photocatalysts such as TiO2, ZnO, Fe2O3, CdS, ZnS, etc. absorbs light of energy greater than or equal to its band gap and the electron in the valence band gets excited to conduction band leaving behind the hole in valence band. These charge carrier...

  16. Theoretical Studies of the Mechanisms of the Entry of Virus into Cells

    Mulampaka, Shiva Naresh
    Viruses cause human diseases by entering in to human cells. Many drugs have been developed that act at various stages of viral infection, but they fail due to their toxic side effects and high mutation rates of viruses. Recently, a new class of drugs called entry inhibitors has been developed which acts on the early stages of viral infection. These drugs have been developed by studying the entry process of viruses in to host cells. The success of these drugs, however, is still limited and research is being done to quantify the optimum dosage of these drugs and find new...

  17. Engineering the N-Glycosylation Pathway in Pichia Pastoris for the Expression of Glycoprotein Hormones

    Manoharan, Simna
    Proteins, participating in a myriad of biological function, are at the core of all cellular activities occurring within living organisms. Therapeutic proteins, hence constitute a major part of the pharmaceutical industry. The glycoprotein hormones follicle stimulating hormone (FSH), luteinizing hormone (LH), thyroid stimulating hormone (TSH) and human chorionic gonadotropin (CG) regulate various reproductive and metabolic functions in humans and hence have high therapeutic potentials. The increasing demand of recombinant proteins for therapeutic uses drives the development of better expression systems. The methylotrophic yeast Pichia pastoris, has been termed as an industrial workhorse for heterologous protein expression. However, the N-glycosylation in...

  18. Turbulence in Soft Walled Micro Channels

    Srinivas, S S
    In comparison to the flow in a rigid channel, there is a multi-fold reduction in the transition Reynolds number for the flow in a micro channel when one of the walls is made sufficiently soft, due to a dynamical instability induced by the fluid-wall coupling. The flow after transition is characterized using Particle Image Velocimetry (PIV) in the x − y plane where x is the stream-wise direction and y is the cross-stream co-ordinate along the small dimension of the channel of height 0.2 − 0.3mm. For the two different soft walls of shear modulus 18 kPa and 2.19 kPaused...

  19. Turbulence in Soft Walled Micro Channels

    Srinivas, S S
    In comparison to the flow in a rigid channel, there is a multi-fold reduction in the transition Reynolds number for the flow in a micro channel when one of the walls is made sufficiently soft, due to a dynamical instability induced by the fluid-wall coupling. The flow after transition is characterized using Particle Image Velocimetry (PIV) in the x − y plane where x is the stream-wise direction and y is the cross-stream co-ordinate along the small dimension of the channel of height 0.2 − 0.3mm. For the two different soft walls of shear modulus 18 kPa and 2.19 kPaused...

  20. Modelling And Experimental Investigation into Soluble Lead Redox Flow Battery : New Mechanisms

    Nandanwa, Mahendra N
    Continued emission of green house gases has energized research activity worldwide to develop efficient ways to harness renewal energy. The availability of large scale energy storage technologies is essential to make renewal energy a reliable source of energy. Redox flow batteries show potential in this direction. These batteries typically need expensive membranes which need replacement be-cause of fouling. The recently proposed soluble lead redox flow battery (SLRFB), in which lead ions deposit on electrodes in charge cycle and dissolve back in discharge cycle, can potentially cut down the cost of energy storage by eliminating membrane. A number of challenges need...

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