Recursos de colección

ETD at Indian Institute of Science (3.354 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 48

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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,...

  6. 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....

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. An Application Of Cybernetic Principles To The Modeling And Optimization Of Bioreactors

    Mandli, Aravinda Reddy
    The word cybernetics has its roots in the Greek word \kybernetes" or \steers-man" and was coined by Norbert Wiener in 1948 to describe \the science of control and communication, in the animal and the machine". The discipline focuses on the way various complex systems (animals/machines) steer towards/maintain their goals utilizing information, models and control actions in the face of various disturbances. For a given animal/machine, cybernetics considers all the possible behaviors that the animal/machine can exhibit and then enquires about the constraints that result in a particular behavior. The thesis focuses on the application of principles of cybernetics to the...

  16. An Application Of Cybernetic Principles To The Modeling And Optimization Of Bioreactors

    Mandli, Aravinda Reddy
    The word cybernetics has its roots in the Greek word \kybernetes" or \steers-man" and was coined by Norbert Wiener in 1948 to describe \the science of control and communication, in the animal and the machine". The discipline focuses on the way various complex systems (animals/machines) steer towards/maintain their goals utilizing information, models and control actions in the face of various disturbances. For a given animal/machine, cybernetics considers all the possible behaviors that the animal/machine can exhibit and then enquires about the constraints that result in a particular behavior. The thesis focuses on the application of principles of cybernetics to the...

  17. Studies On Fabrication And Characterisation Of TiO2 Based Dye-Sensitised Solar Cells

    Sharmila, S
    Photovoltaic cells are a promising solution to the current energy crisis. Among the different photovoltaic cell technologies developed, dye-sensitised solar cells (DSSC) are emerging as viable low-cost alternatives to Si PV technology. This thesis presents studies on fabrication and characterisation of TiO2 based dye-sensitised solar cells. Chapter 1 gives an overview of different photovoltaic cell technologies and a review of the state-of-the art DSSC technology. Chapter 2 describes the techniques used for characterisation of DSSCs. Chapter 3 describes the fabrication of TiO2 based dye-sensitised solar cells. Chapter 4 presents the analysis of measurements obtained by the characterisation techniques. Finally chapter...

  18. Studies On Fabrication And Characterisation Of TiO2 Based Dye-Sensitised Solar Cells

    Sharmila, S
    Photovoltaic cells are a promising solution to the current energy crisis. Among the different photovoltaic cell technologies developed, dye-sensitised solar cells (DSSC) are emerging as viable low-cost alternatives to Si PV technology. This thesis presents studies on fabrication and characterisation of TiO2 based dye-sensitised solar cells. Chapter 1 gives an overview of different photovoltaic cell technologies and a review of the state-of-the art DSSC technology. Chapter 2 describes the techniques used for characterisation of DSSCs. Chapter 3 describes the fabrication of TiO2 based dye-sensitised solar cells. Chapter 4 presents the analysis of measurements obtained by the characterisation techniques. Finally chapter...

  19. Computational Study Of Long Chain N-alkane Binary Mixture Adsorption In Silicalite Under Conditions Of High Loading

    Ganesh, Hari S
    The study of adsorption of n-alkanes in zeolite pores represents both a fundamental problem in molecular thermodynamics and also a problem with substantial industrial importance. Until mid 19th century, adsorption was mainly used for purification processes such as removal of H2S and mercaptans from natural gas and organic matter from water. However, with the emergence of molecular sieves, especially zeolites, adsorption processes have become an attractive alter- native to distillation in large scale separation of mixtures that have low relative volatility into streams each enriched in one of the components. The pore di- ameters of molecular sieves are of the...

  20. Modeling The Population Dynamics Of Erythrocytes To Identify Optimal Drug Dosages For The Treatment Of Hepatitis C Virus Infection

    Krishnan, Sheeja M
    The current treatment for hepatitis C virus (HCV) infection – combination therapy with pegylated interferon and ribavirin – elicits sustained responses in only ~50% of the patients treated. Greater cumulative exposure to ribavirin increases response to interferon-ribavirin combination therapy. A key limitation, however, is the toxic sideeffect of ribavirin, hemolytic anemia, which often necessitates a reduction of ribavirin dosage and compromises treatment response. Maximizing treatment response thus requires striking a balance between the antiviral and hemolytic activities of ribavirin. Current models of viral kinetics describe the enhancement of treatment response due to ribavirin. Ribavirin-induced anemia, however, remains poorly understood and precludes rational optimization of combination therapy. Here, we...

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