Ab Initio Investigation On The Surface Chemistry Of Functionalized Titania Membranes,
2020
University of Kentucky
Ab Initio Investigation On The Surface Chemistry Of Functionalized Titania Membranes, Evan Hyde
Theses and Dissertations--Chemical and Materials Engineering
Titania (titanium dioxide) is a metal oxide which has recently been investigated as a photocatalyst, most commonly for use in hydrolysis, which absorbs mostly in the UV range. However, the range of absorption can be shifted to fall within the visible light range either by doping or by functionalizing the surface with atomic or molecular adsorbates. Over the course of this research, a series of Density Functional Theory (DFT) calculations are performed to ascertain the effects of these different methods on the photocatalytic performance of titania. While the effects of nitrogen doping and oxygen vacancies are well known, more recent …
Electrophoresis In Heterogeneous Hydrogels And Applications In Surface Patterning,
2020
University of Kentucky
Electrophoresis In Heterogeneous Hydrogels And Applications In Surface Patterning, Ning Ge
Theses and Dissertations--Mechanical and Aerospace Engineering
The creation of chemical micropatterns on surfaces makes it possible to add unique chemical functionality to surfaces, modifying properties such as wettability, or even adding the ability to selectively bind other molecules. The creation of biochemical surface patterning in particular is useful in a variety of fields including tissue engineering and highthroughput drug screening. There are many existing surface patterning techniques which focus on precise control over the patterned geometry, even down to submicron scale features, but they do not allow local control over chemical concentration. So the results are high resolution patterns with binary concentration. There are also existing …
Gravity-Drawing Flexible Silicone Filaments As Fiber Optics And Model Foldamers,
2020
Claremont Colleges
Gravity-Drawing Flexible Silicone Filaments As Fiber Optics And Model Foldamers, Katherine Snell
CMC Senior Theses
Here, we present a method of gravity-drawing polydimethylsiloxane (PDMS) silicone fibers with application as fiber optics and as model foldamers. Beginning as a viscous liquid, PDMS is cured using heat until its measured viscosity reaches 4000 mPa•s. The semi-cured elastomer is then extruded through a tube furnace to produce thin (diameters on the order of hundred micrometers) filaments with scalable lengths. PDMS is biocompatible, gas-permeable, flexible, and hydrophobic. Additionally, the PDMS surface hydrophobicity can be modified via UV exposure, O2 plasma, and corona discharge. We demonstrate the patternibility (i.e patterns of hydrophobicity) of PDMS fibers, adding complexity to potential foldamer …
Sensitivity And Uncertainty Quantification Of Continuum And Stochastic Bond Dissociation Kinetics Based Cohesive Laws,
2020
Michigan Technological University
Sensitivity And Uncertainty Quantification Of Continuum And Stochastic Bond Dissociation Kinetics Based Cohesive Laws, Rishabh Awasthi
Dissertations, Master's Theses and Master's Reports
Polymeric adhesives are being extensively used to develop light weight and durable Composite Materials which are have been employed in automotive, aeronautical, medical industry. Polymeric adhesives undergo failure due to relative opening sliding of bonded interfaces which requires a need to characterize the fracture mechanism. Numerous experiments are conducted to predict the fracture response for Mode-I, II,III and numerical simulations are employed to inversely calibrate the material parameters governing the constitutive laws. Cohesive zone models are largely employed in fracture mechanics to predict failure of interfaces undergoing large plastic deformations. The objective of this report is to employ the cohesive …
Multiscale Modeling Of Carbon Fibers/Graphene Nanoplatelets/Epoxy Hybrid Composites For Aerospace Applications,
2020
Michigan Technological University
Multiscale Modeling Of Carbon Fibers/Graphene Nanoplatelets/Epoxy Hybrid Composites For Aerospace Applications, Hashim Al Mahmud
Dissertations, Master's Theses and Master's Reports
Significant research effort has been dedicated for decades to improve the mechanical properties of aerospace polymer-based composite materials. Lightweight epoxy-based composite materials have increasingly replaced the comparatively heavy and expensive metal alloys used in aeronautical and aerospace structural components. In particular, carbon fibers (CF)/graphene nanoplatelets (GNP)/epoxy hybrid composites can be used for this purpose owing to their high specific stiffness and strength. Therefore, this work has been completed to design, predict, and optimize the effective mechanical properties of CF/GNP/epoxy composite materials at different length scales using a multiscale modeling approach. The work-flow of modeling involves a first step of using …
Virus Purification Framework And Enhancement In Aqueous Two-Phase System,
2020
Michigan Technological University
Virus Purification Framework And Enhancement In Aqueous Two-Phase System, Pratik Umesh Joshi
Dissertations, Master's Theses and Master's Reports
Viral infections regularly pose detrimental health risks to humans. Preventing viral infections through global immunization requires the production of large doses of vaccines. The increasing demand for vaccines, especially during pandemics such as COVID-19, has challenged current manufacturing strategy to develop advanced unit operations with high throughput capability. Over the decade, the upstream processing responsible for synthesizing viral products in cell cultures has shown significant success in yielding high titers of viruses and virus-like particles. The progress in the upstream stage has now shifted the bottleneck to the downstream processing (DSP). Overlooked for decades, the DSP responsible for viral product …
Impact Of Chain Architecture On The Thickness Dependence Of Physical Aging Rate Of Thin Polystyrene Films,
2020
University of Akron
Impact Of Chain Architecture On The Thickness Dependence Of Physical Aging Rate Of Thin Polystyrene Films, Gregory Brown, Elizabeth Lewis, Bryan D. Vogt
Williams Honors College, Honors Research Projects
The dynamics of polymer thin films have been demonstrated to be significantly altered from the bulk, but the origins of such differences are not well defined. In this work, we seek to understand the differences in the structural dynamics (or physical aging) of polystyrene (PS) through branching and other well defined architectures (comb and centipede). The aging dynamics of ultrathin films (< 30 nm) differ from relatively thick films (100-150nm) with linear PS thin films aging more rapidly than the relatively “bulk-like” thick films. Ellipsometric measurements are used to characterize the physical aging rate of the films. The change in film thickness and refractive index as the films are held below the glass transition temperature (Tg) provides a simple measure of the physical aging. In this study, four different architectures (linear, comb, 4 arm star, and centipede) will be investigated. For each PS architecture, the aging rate will be determined for film …
A Foundational Approach To Extrusion And Compounding,
2020
The University of Akron
A Foundational Approach To Extrusion And Compounding, David Frankart
Williams Honors College, Honors Research Projects
With a history of nearly 200 years, polymer processing and compounding is constantly changing to fit the material science needs of the era. Exposure of undergraduate students to the technology and practices used in industry today in a lab setting would create new opportunities for experiential learning and growth. The objective was to set up a 0.75”, 25 L/D Thermo Haake single screw extruder for lab use and run trials of material in a single screw extruder to set up a basis for experiments. Trials were run of co-polyester resin through a single screw extruder with carbon fiber additives varying …
Solvent-Free Coating Using Maco Bio-Based Reactive Diluent,
2020
The University of Akron
Solvent-Free Coating Using Maco Bio-Based Reactive Diluent, Ryder James
Williams Honors College, Honors Research Projects
The project performed utilizes methacrylated cardanol (MACO) and a linseed oil resin to test how different weight percentages of MACO affect coating performance. MACO is synthesized from a phenolic lipid extracted from cashew nut shells, which are a cashew industry waste product. Not only does it utilize a waste product, but being a bio-based reactive diluent means it can replace the use of volatile organic solvents that are harmful to both humans and the environment. Weight percentage samples of 0%, 10%, 20%, 30%, and 40% were used. Coatings were applied using a 6-mil drawn down bar, with samples being prepared …
Nanostructured Metal Thin Films As Components Of Composite Membranes For Separations And Catalysis,
2020
University of Kentucky
Nanostructured Metal Thin Films As Components Of Composite Membranes For Separations And Catalysis, Michael J. Detisch
Theses and Dissertations--Chemical and Materials Engineering
Novel metallic thin film composite membranes are synthesized and evaluated in this work for improved separations and catalysis capabilities. Advances in technology that allow for improved membrane performance in solvent separations are desirable for low molecular weight organic separation applications such as those in pharmaceutical industries. Additionally, the introduction of catalytic materials into membrane systems allow for optimization of complex processes in a single step. By adding a nanostructured metallic thin film to its surface, a polymer membrane may be modified to exhibit these improved properties. Using magnetron sputtering, thin metal films may be deposited on commercially available membranes to …
Interfaces In Lead-Free Tin Perovskite Photovoltaics: An Investigation Of Energetics, Ion Mobility, Surface Modification, And Performance,
2020
University of Kentucky
Interfaces In Lead-Free Tin Perovskite Photovoltaics: An Investigation Of Energetics, Ion Mobility, Surface Modification, And Performance, Alex Boehm
Theses and Dissertations--Chemistry
Halide perovskites have generated tremendous interest as low-cost semiconductors for optoelectronics, such as photovoltaics, lasers, and light emitting diodes due to their extraordinary optical and transport properties. Perovskite photovoltaics in particular have demonstrated a meteoric rise in power conversion efficiencies and drawn considerable interest as a next-generation solar energy technology. The rapid development has centered around lead-based derivatives, and concerns regarding the toxicity of lead has sparked interest in low toxicity and more environmentally friendly perovskite derivatives. In this regime tin (Sn) is regarded as a prominent alternative owing to the ideal bandgap and reduced toxicity exhibited by Sn-halide perovskites. …
A Theoretical And Experimental Study Of Charge Transport In Organic Thermoelectric Materials And Charge Transfer States In Organic Photovoltaics,
2020
University of Kentucky
A Theoretical And Experimental Study Of Charge Transport In Organic Thermoelectric Materials And Charge Transfer States In Organic Photovoltaics, Ashkan Abtahi
Theses and Dissertations--Physics and Astronomy
Applications of organic electronics have increased significantly over the past two decades. Organic semiconductors (OSC) can be used in mechanically flexible devices with potentially lower cost of fabrication than their inorganic counterparts, yet in many cases organic semiconductor-based devices suffer from lower performance and stability. Investigating the doping mechanism, charge transport, and charge transfer in such materials will allow us to address the parameters that limit performance and potentially resolve them. In this dissertation, organic materials are used in three different device structures to investigate charge transport and charge transfer. Chemically doped π-conjugated polymers are promising materials to be used …
Artificial Synthetic Scaffolds For Tissue Engineering Application Emphasizing The Role Of Biophysical Cues,
2020
Michigan Technological University
Artificial Synthetic Scaffolds For Tissue Engineering Application Emphasizing The Role Of Biophysical Cues, Samerender Nagam Hanumantharao
Dissertations, Master's Theses and Master's Reports
The mechanotransduction of cells is the intrinsic ability of cells to convert the mechanical signals provided by the surrounding matrix and other cells into biochemical signals that affect several distinct processes such as tumorigenesis, wound healing, and organ formation. The use of biomaterials as an artificial scaffold for cell attachment, differentiation and proliferation provides a tool to modulate and understand the mechanotransduction pathways, develop better in vitro models and clinical remedies. The effect of topographical cues and stiffness was investigated in fibroblasts using polycaprolactone (PCL)- Polyaniline (PANI) based scaffolds that were fabricated using a self-assembly method and electrospinning. Through this …
The Study Of Chemical Induced Polyolefin-Based Ion Exchange Membrane For Electrodialysis Application,
2020
Michigan Technological University
The Study Of Chemical Induced Polyolefin-Based Ion Exchange Membrane For Electrodialysis Application, Di Huang
Dissertations, Master's Theses and Master's Reports
High-performance ion exchange membranes with high ion exchange capacity (IEC), excellent mechanical properties, lower membrane resistance and superior ions conductivity were developed with chemical-induced polymerization in this work. Through a series of synthesizing experiments, structure characterization and properties testing for polyolefin-based cation exchange membrane (CEM) and anion exchange membrane (AEM), LDPE proved to be an optimized backbone material. The CEM with 57.5% styrene, 38.4% LDPE, 3% crosslinking degree and 1% initiator addition yield the highest IEC value (1.72 mol/g) and moderate burst strength. The 10% addition of styrene was found to enhance IEC of 57% to AEM. However, continually increase …
Strengthening Of Corroded Steel Structures Using Cfrp – An Experimental Review,
2019
Arab Contractors
Strengthening Of Corroded Steel Structures Using Cfrp – An Experimental Review, Ghada El-Mahdy Ph.D., P.Eng, Abdallah H. Yassin, Abdel El Rahman Khaled
Civil Engineering
Fibre reinforced polymers (FRP) have been widely used to strengthen reinforced concrete structures, however, nowadays their use to strengthen steel structures is under investigation. In particular, the need to strengthen corroded steel structures found in aggressive environments, such as marine environments, which have undergone a reduction in cross-sectional area and hence a reduction in their load-carrying capacity is in need of studying. The main problems that arise when using carbon fibre reinforced polymer (CFRP) sheets to strengthen steel structures is the weakness in the interfacial bond between the CFRP and the steel surface, the thinness of CFRP sheet, and the …
Ph-Sensitive Oxygen Release Microspheres To Enhance Cell Survival In Ischemic Condition,
2019
Washington University in St. Louis
Ph-Sensitive Oxygen Release Microspheres To Enhance Cell Survival In Ischemic Condition, Zhongting Liu
McKelvey School of Engineering Graduate Student Theses & Dissertations
Ischemic diseases such as myocardial infarction, stroke and limb ischemia are severe cardiovascular diseases with high rate of death and millions of people suffered from these diseases. Under ischemic environment, cells die due to deficient supply of nutrient and oxygen. To regenerate ischemic tissues, stem cell therapy is a promising approach because stem cells can differentiate into cells necessary for the regeneration. However, stem cell therapy has limitations. For example, few cells can survive under harsh ischemic environment. To enhance stem cells survival, implantation of oxygen release microspheres to sustained supply cells with oxygen represents an effective strategy. Previously, our …
Effect Of Incorporating Pottery And Bottom Ash As Partial Replacement Of Cement,
2019
The Islamic University of Gaza
Effect Of Incorporating Pottery And Bottom Ash As Partial Replacement Of Cement, Bassam A. Tayeh, Doha M. Alsaffar, Lawend K. Askar, Asmahan Issa Jubeh
Karbala International Journal of Modern Science
This study addressed the environmental constraints in cement production. Ordinary Portland cement (OPC) was replaced with pottery powder (PP, produced by grinding locally available pottery) and bottom ash (BA) at 10%, 20% and 30% of cement mass. Moreover, 4% calcium chloride solution (CaCl2.2H2O) was used as mixing water. Material properties, such as standard consistency, setting time and compressive strength, were measured with different percentages of OPC replacement with PP and BA. Results indicated that the replacement with PP and BA increased the water demand to achieve the standard consistency. These results revealed that the strength evolution …
Towards Completely Automated Glycan Synthesis,
2019
University of Missouri-St. Louis
Towards Completely Automated Glycan Synthesis, Matteo Panza
Dissertations
Carbohydrates are ubiquitous both in nature as biologically active compounds and in medicine as pharmaceuticals. Although there has been continued interest in the synthesis of carbohydrates, chemical methods require specialized knowledge and hence remain cumbersome. The need for development of rapid, efficient and operationally simple procedures has come to the fore. This dissertation focuses on the development of a fully automated platform that will enable both experts and non-specialists to perform the synthesis of glycans. Existing automated methods for the synthesis of oligosaccharides are highly sophisticated, operationally complex, and require significant user know-how. By contrast, high performance liquid chromatography (HPLC) …
Sorbents For Cleaning Of Vegetable Oils,
2019
Karshi Engineering Economic Institute, Uzbekistan
Sorbents For Cleaning Of Vegetable Oils, Ikromov Oybek, Suvanova Fayoza, Farmonov Jasur
CHEMISTRY AND CHEMICAL ENGINEERING
The article presents the results of the study of adsorbents obtained from rice husk. To increase the sorption capacity of the raw material is treated with hydrogen peroxide for 30 minutes and subjected to roasting. Before thermal activation, the resulting mass was treated with a 30% alumium calcium alum solution. Reagent consumption is 20% of the mass of the adsorbent. The alum-enriched adsorbent is thermally activated at a temperature of 300-800 °C without oxygen access for two hours. According to the results of laboratory tests, the adsorbents that have undergone thermal activation at a temperature of 500-800 °C have the …
Development Of Environmentally Friendly Drilling Fluids In Order To Reduce The Anthropogenic Impact On The Environment,
2019
JSC Institute of geology and exploration of oil and gas fields, Tashkent, Uzbekistan
Development Of Environmentally Friendly Drilling Fluids In Order To Reduce The Anthropogenic Impact On The Environment, Arslanova Nodirakhon, Arslanov Sharafutdin, Zavorotnyy Vitaliy Leonidovich
CHEMISTRY AND CHEMICAL ENGINEERING
The article discusses natural clay as a raw material for drilling fluids of the oil and gas industry of the Republic of Uzbekistan. Studied compositions of clays from the Akoy and Navbakhor area (the Republic of Uzbekistan) and Tagansky area (Republic of Kazakhstan) were. Evaluated technological parameters of clay powders based on the original and modified explored clays. Were determined modifying additives (2.0% Na2CO3 and PAA 0.25%) to obtain low-toxic clay powders that do not have a technogenic impact on the environment during the drilling process. Calculations are confirmed by the results of bio-testing using standard methods based on the …
