Browsing by Author "Tour, James"

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    Advanced Applications of Polymers for Enhanced Oil Recovery
    (2014-11-06) ShamsiJazeyi, Hadi; Hirasaki, George J; Verduzco, Rafael; Tour, James; Biswal, Lisa
    With the increasing global demand for crude oil, it is essential to increase the oil production in economic ways. This requires a significant increase in application of advanced technologies in this area. Enhanced Oil Recovery (EOR) processes are known as series of different advanced technologies, which can be used to increase the oil production from a given oil reservoir. The traditional use of polymers in EOR is almost limited to increasing viscosity of the aqueous fluids injected into the reservoir. By increasing the viscosity of the injected fluids, more areas of the reservoir can be swept, and therefore more oil is expected to be recovered. In this thesis proposal, a number of advanced polymer applications for EOR are investigated. Polymers are known as a very promising class of materials with wide range of properties, especially combined with other advanced materials, such as nanoparticles. Therefore, there is a huge potential for developing new application of polymers in EOR processes. The first application introduced in this thesis is to use polymers as sacrificial adsorption agents for anionic surfactants. In a subclass of EOR, known as chemical EOR, surfactants are injected to lower the interfacial tension of oil and brine, resulting in recovery of more oil. However, one of the challenges facing these processes is the adsorption of surfactants onto the reservoir rock, which requires excessive injection of surfactant to compensate for the adsorption. This significantly increases the cost of the chemical EOR to values much more than what is actually needed for oil recovery. In second chapter of this thesis, sodium polyacrylate is introduced as a sacrificial adsorption agent, a chemical that is injected to decrease the adsorption of anionic surfactant. The results show that the material cost of chemical EOR can be reduced by up to 80% in case of using polyacrylate as a sacrificial agent for anionic surfactants. In addition, application of polyacrylate as a sacrificial agent for zwitterionic surfactants was investigated. In spite the significant reduction seen in the adsorption of anionic surfactants once polyacrylate is used, adsorption of zwitterionic surfactants is only slightly reduced after adding polyacrylate. In order to understand the reasons behind this dismal reduction, the effect of pH on adsorption of lauryl betaine (as the zwitterionic surfactant in this study) is studied. Based on the experimental data, a hypothetic mechanism is introduced to explain the adsorption properties of betaine. This hypothetic mechanism also explains why polyacrylate shows a very slight reduction in adsorption of zwitterionic surfactants while it significantly reduces adsorption of anionic surfactants. Finally, the effect of polymer coating on interfacial properties of nanoparticles in the absence or presence of surfactants is studied. Interfacial properties of polymer-coated nanoparticles in EOR have been traditionally limited to only emulsions (Pickering Emulsions). In this thesis, we have provided experimental evidence that polymer-coated nanoparticles can migrate to micro-emulsion phases even in the absence of emulsions. Some of these polymer-coated nanoparticles are dispersed in aqueous solutions, but they will precipitate in the micro-emulsion phase once mixed with the oil. This observation by itself can be used in EOR applications through understanding the fact that aqueous stability of nanoparticles is not the sufficient condition for nanoparticles to remain stable when injected into oil reservoirs. Many previous researchers have only focused on stability of nanoparticles in aqueous solutions as the only requirement for stability of nanoparticles even after injection into oil reservoir. This assumption is challenged based on our work in this thesis.
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    Advances in Carbon Nanotechnology: Non-Equilibrium Graphene Synthesis and the Control of Cell Signaling with Molecular Machines
    (2023-08-11) Beckham, Jacob Lee; Tour, James; Pasquali, Matteo
    Carbon, known as the "element of life," has long fascinated researchers due to its exceptional versatility as a molecular building block. With its ability to form a wide range of molecular structures and exhibit diverse bonding configurations, carbon has become the cornerstone of countless organic compounds. In recent years, this inherent versatility has taken on a new dimension with the emergence of carbon nanomaterials, including carbon nanotubes, graphene, and, indeed, even buckminsterfullerenes. These materials hold immense promise for the advancement of both science and industry. This thesis presents several major advances in the field of carbon nanotechnology. First, various investigations of non-equilibrium graphene synthesis techniques are discussed. Second, the use of carbon-based molecular nanomotors to control cell signaling is explored. In the first several chapters, explorations using different non-equilibrium synthesis techniques to generate graphene are presented. Chapter 1 explores the conversion of positive photoresist into laser-induced graphene, demonstrating that a combination of lasing and photolithography allows the patterning of graphene at high resolution. Chapter 2 presents machine learning models trained to predict the extent of crystallization in beds of amorphous carbon treated with an electrothermal discharge. This work comprised a major thrust in our lab’s research program on flash Joule heating and revealed several key factors for the design of Joule heating reactors. This work also presented software programs capable of learning to synthesize graphene from scrap rubber tires with no human oversight using Bayesian meta-learning. Chapter 3 represents a pivot in my PhD where I began exploring the biomedical applications of carbon nanomaterials. In the Tour lab, we explore the use of carbon-based molecular motors for various applications in biology. These molecular motors convert incident photons into mechanical work through a series of photochemical and thermal steps. Our previous work has shown that the actuation of fast molecular motors causes the permeabilization of lipid bilayers. Chapter 3 is a perspective discussing the potential applications of these motors, laying out foundational standards for the literature. This chapter discusses how to differentiate the light-driven effects of molecular actuation and potential confounding factors, including photothermal and photodynamic effects. Chapter 4 then demonstrates the use of these molecular motors for the treatment of fungal infections. This work involved extensive microscopy and fundamental studies showing how our motors are processed by eukaryotes, and what that might imply for their basic mechanism-of-action. Chapter 5 explores the use of these molecular motors to control cell signaling. When they are mechanically perturbed, cells participate in mechanosensitive signaling phenomena known as intercellular calcium waves. Thirty years ago, cell biologists used to study calcium waves initiated by poking cells with a micropipette. My work showed that the same responses could be achieved using a fast, unidirectional molecular motor. This work represents the first demonstration that a cell signaling cascade could be initiated by the mechanical force administered by a small molecule, opening the door for the design of new drugs that work based on mechanical, rather than chemical, forces. Chapter 6 explores the dependence of motor performance on the functionalization chemistry used in the motor. Our findings indicate that surface charge and polarity are critical factors that drive motor effectiveness for killing bacteria, killing fungi, and initiating calcium waves. We found substantial overlap in motor performance across all three tasks. Finally, Chapter 7 explores the use of molecular motors to control endocrine signaling. This chapter shows that light-activated motors can potentiate the release of insulin from pancreatic beta cells through the modulation of intracellular calcium, a finding with substantial implications for the design of new drugs to treat diabetes.
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    Growth of graphene films from non-gaseous carbon sources
    (2015-08-04) Tour, James; Sun, Zhengzong; Yan, Zheng; Ruan, Gedeng; Peng, Zhiwei; Rice University; United States Patent and Trademark Office
    In various embodiments, the present disclosure provides methods of forming graphene films by: (1) depositing a non-gaseous carbon source onto a catalyst surface; (2) exposing the non-gaseous carbon source to at least one gas with a flow rate; and (3) initiating the conversion of the non-gaseous carbon source to the graphene film, where the thickness of the graphene film is controllable by the gas flow rate. Additional embodiments of the present disclosure pertain to graphene films made in accordance with the methods of the present disclosure.
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    Selective accretion of cytoprotectant in radiation-sensitive tissues and uses thereof
    (2022-10-25) Tour, James; Taniguchi, Cullen; Mason, Kathy; Rice University; William Marsh Rice University; The Board of Trustees of the Leland Stanford Junior University; Board of Regents, University of Texas System; United States Patent and Trademark Office
    The disclosure relates to the treatment of primary and metastatic cancer using radiation. Specifically, the disclosure relates to methods providing for the selective accretion of cytoprotective agent in tissues and/or organs, sensitive to radiation that are adjacent to malignant tumors prior to radiation of the tumors at a dose that otherwise would be toxic to the tissues and/or organs, but are necessary to achieve ablative outcome on the tumors.