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- Genre: Masters Thesis
Description
Granulation is a process within particle technology where a liquid binding agent is added to a powder bed to create larger granules to modify bulk properties for easier processing. Three sets of experiments were conducted to screen for which factors had the greatest effect on granule formation, size distribution, and morphological properties when wet granulating microcrystalline cellulose and water. Previous experiments had identified the different growth regimes within wet granulation, as well as the granule formation mechanisms in single-drop granulation experiments, but little research has been conducted to determine how results extracted from single drop experiments could be used to better understand the first principles that drive high shear granulation. The experiment found that under a liquid solid ratio of 110%, the granule growth rate was linear as opposed to the induction growth regime experienced at higher liquid solid ratios. L/S ratios less than 100% led to a bimodal distribution comprised of large distributions of ungranulated powder and large irregular granules. Insufficient water hampered the growth of granules due to lack of enough water bridges to connect the granules and powder, while the large molecules continued to agglomerate with particles as they rotated around the mixer. The nozzle end was augmented so that drop size as well as drop height could be adjusted and compared to single-drop granulation experiments in proceeding investigations. As individual factors, neither augmentation had significant contributions to granule size, but preliminary screens identified that interaction between increasing L/S ratio and decreasing drop size could lead to narrower distributions of particles as well as greater circularity. Preliminary screening also identified that decreasing the drop height of the nozzle could increase the rate of particle growth during the 110% L/S trials without changing the growth mechanisms, indicating a way to alter the rate of steady-state particle growth. This paper screens for which factors are most pertinent to associating single-drop and wet granulation in order to develop granulation models that can ascertain information from single-drop granulations and predict the shape and size distribution of any wet granulation, without the need to run costly wet granulation experiments.
ContributorsLay, Michael (Author) / Emady, Heather (Thesis advisor) / Muhich, Christopher (Committee member) / Holloway, Julianne (Committee member) / Arizona State University (Publisher)
Created2019
Description
Amphipathic molecules consist of hydrophilic and hydrophobic regions, which make them surface-active molecules. The uniqueness of these compounds results in inducing low surface tension and self-assembly of the molecules inside a solvent which have been exploited in personal care, the oil industry and agriculture industry. Amphipathic molecules are also used in the healthcare industry as drug delivery systems and other bio-nanotechnology applications.
In this thesis, a novel series of grafted siloxanes have been explored for their probable application in the healthcare industry. The siloxanes are grafted with poly(ethylene glycol) (PEG) and quaternary ammonium salt (QUAT). The effects of varying 1) molar ratios of QUAT to PEG and 2) PEG chain length on contact angle, surface tension, critical micelle concentration (CMC), and micelle assembly properties were studied. In contact angle experiments, the hydrophilicity of grafted siloxanes increased by grafting PEG and QUAT. The amphiphilicity increases and CMC decreases as the PEG chain length shortens. Adding QUAT also reduces CMC. These trends were observed in surface tension and Isothermal Titration Calorimetry experiments. A change in self-assembly behaviour was also observed in Dynamic Light Scattering experiments upon increasing the PEG chain length and its ratio relative to the quaternary ammonium in the siloxane polymer.
These polymers have also been studied for their probable application as a sensitive 1H NMR spectroscopy indicator of tissue oxygenation (pO2) based on spectroscopic spin-lattice relaxometry. The proton imaging of siloxanes to map tissue oxygenation levels (PISTOL) technique is used to map T1 of siloxane polymer, which is correlated to dynamic changes in tissue pO2 at various locations by a linear relationship between pO2 and 1/T1. The T1-weighted echo spin signals were observed in an initial study of siloxanes using the PISTOL technique.
The change in the ratio of QUAT to PEG and the varying chain length of PEG have a significant effect on the physical property characteristics of siloxane graft copolymers. The conclusions and observations of the present work serve as a benchmark study for further development of adaptive polymers and for the creation of integrated “nanoscale” probes for PISTOL oximetry and drug delivery.
In this thesis, a novel series of grafted siloxanes have been explored for their probable application in the healthcare industry. The siloxanes are grafted with poly(ethylene glycol) (PEG) and quaternary ammonium salt (QUAT). The effects of varying 1) molar ratios of QUAT to PEG and 2) PEG chain length on contact angle, surface tension, critical micelle concentration (CMC), and micelle assembly properties were studied. In contact angle experiments, the hydrophilicity of grafted siloxanes increased by grafting PEG and QUAT. The amphiphilicity increases and CMC decreases as the PEG chain length shortens. Adding QUAT also reduces CMC. These trends were observed in surface tension and Isothermal Titration Calorimetry experiments. A change in self-assembly behaviour was also observed in Dynamic Light Scattering experiments upon increasing the PEG chain length and its ratio relative to the quaternary ammonium in the siloxane polymer.
These polymers have also been studied for their probable application as a sensitive 1H NMR spectroscopy indicator of tissue oxygenation (pO2) based on spectroscopic spin-lattice relaxometry. The proton imaging of siloxanes to map tissue oxygenation levels (PISTOL) technique is used to map T1 of siloxane polymer, which is correlated to dynamic changes in tissue pO2 at various locations by a linear relationship between pO2 and 1/T1. The T1-weighted echo spin signals were observed in an initial study of siloxanes using the PISTOL technique.
The change in the ratio of QUAT to PEG and the varying chain length of PEG have a significant effect on the physical property characteristics of siloxane graft copolymers. The conclusions and observations of the present work serve as a benchmark study for further development of adaptive polymers and for the creation of integrated “nanoscale” probes for PISTOL oximetry and drug delivery.
ContributorsGupta, Srishti (Author) / Green, Matthew D (Thesis advisor) / Kodibagkar, Vikram (Committee member) / Holloway, Julianne (Committee member) / Arizona State University (Publisher)
Created2018
Description
Rotary drums are commonly used for their high heat and mass transfer rates in the manufacture of cement, pharmaceuticals, food, and other particulate products. These processes are difficult to model because the particulate behavior is governed by the process conditions such as particle size, particle size distribution, shape, composition, and operating parameters, such as fill level and rotation rate. More research on heat transfer in rotary drums will increase operating efficiency, leading to significant energy savings on a global scale.
This research utilizes infrared imaging to investigate the effects of fill level and rotation rate on the particle bed hydrodynamics and the average wall-particle heat transfer coefficient. 3 mm silica beads and a stainless steel rotary drum with a diameter of 6 in and a length of 3 in were used at fill levels of 10 %, 17.5 %, and 25 %, and rotation rates of 2 rpm, 6 rpm, and 10 rpm. Two full factorial designs of experiments were completed to understand the effects of these factors in the presence of conduction only (Case 1) and conduction with forced convection (Case 2). Particle-particle friction caused the particle bed to stagnate at elevated temperatures in Case 1, while the inlet air velocity in Case 2 dominated the particle friction effects to maintain the flow profile. The maximum heat transfer coefficient was achieved at a high rotation rate and low fill level in Case 1, and at a high rotation rate and high fill level in Case 2. Heat losses from the system were dominated by natural convection between the hot air in the drum and the external surroundings.
This research utilizes infrared imaging to investigate the effects of fill level and rotation rate on the particle bed hydrodynamics and the average wall-particle heat transfer coefficient. 3 mm silica beads and a stainless steel rotary drum with a diameter of 6 in and a length of 3 in were used at fill levels of 10 %, 17.5 %, and 25 %, and rotation rates of 2 rpm, 6 rpm, and 10 rpm. Two full factorial designs of experiments were completed to understand the effects of these factors in the presence of conduction only (Case 1) and conduction with forced convection (Case 2). Particle-particle friction caused the particle bed to stagnate at elevated temperatures in Case 1, while the inlet air velocity in Case 2 dominated the particle friction effects to maintain the flow profile. The maximum heat transfer coefficient was achieved at a high rotation rate and low fill level in Case 1, and at a high rotation rate and high fill level in Case 2. Heat losses from the system were dominated by natural convection between the hot air in the drum and the external surroundings.
ContributorsBoepple, Brandon (Author) / Emady, Heather (Thesis advisor) / Muhich, Christopher (Committee member) / Holloway, Julianne (Committee member) / Arizona State University (Publisher)
Created2019
Description
Adoptive cell therapies such as chimeric antigen receptor (CAR) modified immune cells are revolutionizing cancer treatment. These innovative immunotherapies have a promising outlook for liquid cancers, but lack robustness against solid tumors due to complex variables introduced by the tumor microenvironment (TME). Additionally, existing CAR-T cell treatments are commonly accompanied by toxic side effects. However, by grafting a CAR construct onto macrophages, a professional phagocytic innate cell which are actively recruited by solid tumors, the efficacy of this treatment is hoped to be extended beyond hematological malignancies. Moreover, the introduction of energy metabolite-based polymers (EMPs) to provide a sustained release of activating F16BP-poly(I:C) microparticles could address the toxicity complications that arise from CAR treatments. It was determined that PLGA-F16BP-poly(I:C) microparticles allow for CAR-macrophage activation in vitro, though not in a sustained manner. Moreover, F16BP-poly(I:C) microparticles were better geared toward reducing cytokine related toxicity in vitro, with in vivo results remaining inconclusive. These findings suggest prioritization between macrophage activation or cytokine storm reduction would be required at this time, though additional future studies to explore variables such as CAR-macrophage sensitivity and the positive control could help refine this immunotherapy.
ContributorsHalim, Michelle (Author) / Acharya, Abhinav P (Thesis advisor) / Holloway, Julianne (Committee member) / Khalifehzadeh, Layla (Committee member) / Arizona State University (Publisher)
Created2023
Description
Combining 3D bio-printing and drug delivery are promising techniques tofabricate scaffolds with well controlled and patient-specific structures for tissue
engineering. In this study, silk derivatives of bioink were developed consisting of
silk fibroin and gelatin then 3D printed into scaffolds. The scaffolds would be
evaluated for small molecule release, cell growth, degradation, and morphology.
Preparations and design of the scaffolds are major parts of engineering and tissue
engineering. Scaffolds are designed to mimic extracellular matrix by providing
structural support as well as promoting cell attachment and proliferation with
minimum inflammation while degrading at a controlled rate. Scaffolds offers new
potentials in medicine by aiding in the preparation of personalized and controlled
release therapeutic systems.
ContributorsNg, Johnny (Author) / Rege, Kaushal (Thesis advisor) / Holloway, Julianne (Committee member) / Jin, Kailong (Committee member) / Arizona State University (Publisher)
Created2022
Description
High-Density polyethylene (HDPE) is the most used polymer on earth. Since it is used in such large quantities, it has become the most extensively produced polymer on the planet. Unfortunately, the rate of reusing or recycling HDPE is far behind the rate of production leading to plastic pollution. Most of this waste plastic ends up in landfills or incineration to recover energy. Plastic production consumes a lot of energy and is associated with CO2 emissions. This method of disposing plastic only adds to the environmental pollution rather than improving it. Primary reasons for low recycling rate appear to be more political and financial. In the US, the rate of recycling was less than 10% whereas Japan showed a recycling rate of more than 80%. The other aspect of low recycling is financial. In order to make recycling a financially viable process, efforts have to be made to streamline the process of waste collection, segregation and technically feasible process. This study focusses on the technical aspect of the issue. Even though efforts have been made to recycle HDPE, none of the processes have been recycle HDPE with financial viability, recovering full value of plastic, minimum CO2 emissions and minimum change in properties of the polymer. This study focusses on effective recycling of HDPE with minimum change in its properties. Dissolution has been used to dissolve the polymer selectively and then reprecipitating the polymer using a non-solvent to obtain the polymer grains. This is followed by mixing additives to the polymer grains to minimize degradation of the polymer during the extrusion process. The polymer is then extruded in an extruder beyond its melting temperature. This process is repeated for 5 cycles. After each cycle, the polymer is tested for its properties using the Tensile Testing, Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Dynamic Mechanicalii
Analysis (DMA). It was observed that the rheological properties of the polymer were maintained after the 5th recycle whereas the mechanical properties deteriorated after the 2nd recycle. Also, increase in carbonyl index was observed after 5th recycle.
ContributorsSaini, Rahul Rakesh (Author) / Green, Matthew (Thesis advisor) / Holloway, Julianne (Committee member) / Xie, Renxuan (Committee member) / Arizona State University (Publisher)
Created2022
Description
Managing water resources has become one of the most pressing concerns of scientists both in academia and industry. The reverse osmosis (RO) water treatment process is a well-researched technology among the pressure driven processes to produce potable water. RO is an energy intensive process and often RO membranes are susceptible to fouling and scaling that drives up operational cost and hinder the efficiency. To increase the performance of RO membranes the feed water is pretreated to remove pollutants before desalination. This work aims to fabricate pretreatment membranes to prevent the effects of fouling and scaling by introducing hydrophilic character to membrane. This work explores electrospinning, a cost-effective and scalable technique, to blend two polymers into a nonwoven membrane comprised of fibers ~100 nm - 10 µm in diameter.
A rotary drum collector holding the mat was used to simultaneously collect the electrospun hydrophobic poly(vinyl chloride) (PVC) and hydrophilic poly(vinyl alcohol) (PVA) fibers from two separate solutions. The hydrophilicity of the resulting membrane was tuned by controlling the relative deposition rate of PVA onto the co-spun mat. Fiber diameter and morphologies were characterized by scanning electron microscopy, and Fourier-transform infrared spectroscopy and Confocal fluorescence microscopy further confirmed the presence of both polymers. Moreover, a rigorous analysis to map the PVA/PVC concentration was established to accurately report the relative concentrations of the two polymers on the co-spun mat. After electrospinning, the PVA in the co-spun mats were cross-linked with poly(ethylene glycol) diacid to impart mechanical strength and tune the porosity.
EDS analysis revealed inconsistencies in the mass deposition of both polymers suggesting an improvement in the current experimental design to establish a meaningful relationship between PVA concentration and hydrophilicity. However, tensile test revealed that co-spun mats with high mass flow ratios of PVA possessed high mechanical strength showing a significant improvement in the Young’s Modulus. Furthermore, the co-spun mats were challenged with filtration experiments expecting a positive correlation of flux with PVA concentration. But it was found that with increased concentration, crosslinked PVA constricted PVC fibers minimizing the pores causing a lower flux and a dense membrane structure suitable for filtration.
A rotary drum collector holding the mat was used to simultaneously collect the electrospun hydrophobic poly(vinyl chloride) (PVC) and hydrophilic poly(vinyl alcohol) (PVA) fibers from two separate solutions. The hydrophilicity of the resulting membrane was tuned by controlling the relative deposition rate of PVA onto the co-spun mat. Fiber diameter and morphologies were characterized by scanning electron microscopy, and Fourier-transform infrared spectroscopy and Confocal fluorescence microscopy further confirmed the presence of both polymers. Moreover, a rigorous analysis to map the PVA/PVC concentration was established to accurately report the relative concentrations of the two polymers on the co-spun mat. After electrospinning, the PVA in the co-spun mats were cross-linked with poly(ethylene glycol) diacid to impart mechanical strength and tune the porosity.
EDS analysis revealed inconsistencies in the mass deposition of both polymers suggesting an improvement in the current experimental design to establish a meaningful relationship between PVA concentration and hydrophilicity. However, tensile test revealed that co-spun mats with high mass flow ratios of PVA possessed high mechanical strength showing a significant improvement in the Young’s Modulus. Furthermore, the co-spun mats were challenged with filtration experiments expecting a positive correlation of flux with PVA concentration. But it was found that with increased concentration, crosslinked PVA constricted PVC fibers minimizing the pores causing a lower flux and a dense membrane structure suitable for filtration.
ContributorsMithaiwala, Husain (Author) / Green, Matthew (Thesis advisor) / Dai, Lenore (Committee member) / Holloway, Julianne (Committee member) / Arizona State University (Publisher)
Created2020