Matching Items (776)
Filtering by
- All Subjects: Materials Science
- All Subjects: Biology
- Creators: Arizona State University
Description
The desire to start a family is something millions of people around the globe strive to achieve. However, many factors such as the societal changes in family planning due to increasing maternal age, use of birth control, and ever-changing lifestyles have increased the number of infertility cases seen in the United States each year. Infertility can manifest as a prolonged inability to conceive, or inability to carry a pregnancy full-term. Modern advancements in the field of reproductive medicine have begun to promote the use of Assisted Reproductive Technologies (ART) to circumvent reduced fertility in both men and women. Implementation of techniques such as In Vitro Fertilization, Intracytoplasmic Sperm Injection, and Pre-Implantation Genetic Testing have allowed many couples to conceive. There is continual effort being made towards developing more effective and personalized fertility treatments. This often begins in the form of animal research—a fundamental step in biomedical research. This dissertation examines infertility as a medical condition through the characterization of normal reproductive anatomy and physiology in the introductory overview of reproduction. Specific pathologies of male and female-factor infertility are described, which necessitates the use of ARTs. The various forms of ARTs currently utilized in a clinical setting are addressed including history, preparations, and protocols for each technology. To promote continual advancement of the field, both animal studies and human trials provide fundamental stepping-stones towards the execution of new techniques and protocols. Examples of research conducted for the betterment of human reproductive medicine are explored, including an animal study conducted in mice exploring the role of tyramine in ovulation. With the development and implementation of new technologies and protocols in the field, this also unearths ethical dilemmas that further complicate the addition of new technologies in the field. Combining an extensive review in assisted reproduction, research and clinical fieldwork, this study investigates the history and development of novel research conducted in reproductive medicine and explores the broader implications of new technologies in the field.
ContributorsPeck, Shelbi Marie (Author) / Baluch, Debra P (Thesis advisor) / Maienschein, Jane (Thesis advisor) / Sweazea, Karen (Committee member) / Ellison, Karin (Committee member) / Arizona State University (Publisher)
Created2021
Description
Eusocial insect colonies have often been imagined as “superorganisms” exhibiting tight homeostasis at the colony level. However, colonies lack the tight spatial and organizational integration that many multicellular, unitary organisms exhibit. Precise regulation requires rapid feedback, which is often not possible when nestmates are distributed across space, making decisions asynchronously. Thus, one should expect poorer regulation in superorganisms than unitary organisms.Here, I investigate aspects of regulation in collective foraging behaviors that involve both slow and rapid feedback processes. In Chapter 2, I examine a tightly coupled system with near-instantaneous signaling: teams of weaver ants cooperating to transport massive prey items back to their nest. I discover that over an extreme range of scenarios—even up vertical surfaces—the efficiency per transporter remains constant. My results suggest that weaver ant colonies are maximizing their total intake rate by regulating the allocation of transporters among loads. This is an exception that “proves the rule;” the ant teams are recapitulating the physical integration of unitary organisms.
Next, I focus on a process with greater informational constraints, with loose temporal and spatial integration. In Chapter 3, I measure the ability of solitarily foraging Ectatomma ruidum colonies to balance their collection of protein and carbohydrates given different nutritional environments. Previous research has found that ant species can precisely collect a near-constant ratio between these two macronutrients, but I discover these studies were using flawed statistical approaches. By developing a quantitative measure of regulatory effect size, I show that colonies of E. ruidum are relatively insensitive to small differences in food source nutritional content, contrary to previously published claims.
In Chapter 4, I design an automated, micro-RFID ant tracking system to investigate how the foraging behavior of individuals integrates into colony-level nutrient collection. I discover that spatial fidelity to food resources, not individual specialization on particular nutrient types, best predicts individual forager behavior. These findings contradict previously published experiments that did not use rigorous quantitative measures of specialization and confounded the effects of task type and resource location.
ContributorsBurchill, Andrew Taylor (Author) / Pavlic, Theodore P (Thesis advisor) / Pratt, Stephen C (Thesis advisor) / Hölldobler, Bert (Committee member) / Cease, Arianne (Committee member) / Berman, Spring (Committee member) / Arizona State University (Publisher)
Created2022
Description
Over the past few years, research into the use of doped diamond in electronics has seen an exponential growth. In the course of finding ways to reduce the contact resistivity, nanocarbon materials have been an interesting focus. In this work, the transfer length method (TLM) was used to investigate Ohmic contact properties using the tri-layer stack Ti/Pt/Au on nitrogen-doped n-type conducting nano-carbon (nanoC) layers grown on (100) diamond substrates. The nanocarbon material was characterized using Secondary Ion Mass Spectrometry (SIMS), Scanning electron Microscopy (SEM) X-ray diffraction (XRD), Raman scattering and Hall effect measurements to probe the materials characteristics. Room temperature electrical measurements were taken, and samples were annealed to observe changes in electrical conductivity. Low specific contact resistivity values of 8 x 10^-5 Ωcm^2 were achieved, which was almost two orders of magnitude lower than previously reported values. The results were attributed to the increased nitrogen incorporation, and the presence of electrically active defects which leads to an increase in conduction in the nanocarbon. Further a study of light phosphorus doped layers using similar methods with Ti/Pt/Au contacts again yielded a low contact resistivity of about 9.88 x 10^-2 Ωcm^2 which is an interesting prospect among lightly doped diamond films for applications in devices such as transistors. In addition, for the first time, hafnium was substituted for Ti in the contact stack (Hf/Pt/Au) and studied on nitrogen doped nanocarbon films, which resulted in low contact resistivity values on the order of 10^-2 Ωcm^2. The implications of the results were discussed, and recommendations for improving the experimental process was outlined. Lastly, a method for the selective area growth of nanocarbon was developed and studied and the results provided an insight into how different characterizations can be used to confirm the presence of the nanocrystalline diamond material, the limitations due to the film thickness was explored and ideas for future work was proposed.
ContributorsAmonoo, Evangeline Abena (Author) / Thornton, Trevor (Thesis advisor) / Alford, Terry L (Thesis advisor) / Anwar, Shahriar (Committee member) / Theodore, David (Committee member) / Arizona State University (Publisher)
Created2023
Description
Programmed cell death plays an important role in a variety of processes that promote the survival of the host organism. Necroptosis, a form of programmed cell death, occurs through a signaling pathway involving receptor-interacting serine-threonine protein kinase 3 (RIPK3). In response to vaccinia virus infection, necroptosis is induced through DNA-induced activator of interferon (DAI), which activates RIPK3, leading to death of the cell and thereby inhibiting further viral replication in host cells. DAI also localizes into stress granules, accumulations of mRNAs that have stalled in translation due to cellular stress. The toxin arsenite, a canonical inducer of stress granule formation, was used in this project to study necroptosis. By initiating necroptosis with arsenite and vaccinia virus, this research project investigated the roles of necroptosis proteins and their potential localization into stress granules. The two aims of this research project were to determine whether stress granules are important for arsenite- and virus-induced necroptosis, and whether the proteins DAI and RIPK3 localize into stress granules. The first aim was investigated by establishing a DAI and RIPK3 expression system in U2OS cells; arsenite treatment or vaccinia virus infection was then performed on the U2OS cells as well as on U2OSΔΔG3BP1/2 cells, which are not able to form stress granules. The second aim was carried out by designing fluorescent tagging for the necroptosis proteins in order to visualize protein localization with fluorescent microscopy. The results show that arsenite induces DAI-dependent necroptosis in U2OS cells and that this arsenite-induced necroptosis likely requires stress granules. In addition, the results show that vaccinia virus induces DAI-dependent necroptosis that also likely requires stress granules in U2OS cells. Furthermore, a fluorescent RIPK3 construct was created that will allowfor future studies on protein localization during necroptosis and can be used to answer questions regarding localization of necroptosis proteins into stress granules. This project therefore contributes to a greater understanding of the roles of DAI and RIPK3 in necroptosis, as well as the roles of stress granules in necroptosis, both of which are important in research regarding viral infection and cellular stress.
ContributorsGogerty, Carolina (Author) / Jacobs, Bertram (Thesis advisor) / Langland, Jeffrey (Committee member) / Jentarra, Garilyn (Committee member) / Arizona State University (Publisher)
Created2021
Description
Integrating advanced materials with innovative manufacturing techniques has propelled the field of additive manufacturing into new frontiers. This study explores the rapid 3D printing of reduced graphene oxide/polymer composites using Micro-Continuous Liquid Interface Production (μCLIP), a cutting-edge technology known for its speed and precision. A printable ink is formulated with reduced graphene oxide for μCLIP-based 3D printing. The research focuses on optimizing μCLIP parameters to fabricate reduced graphene composites efficiently. The study encompasses material synthesis, ink formulation and explores the resulting material's structural and electrical properties. The marriage of graphene's unique attributes with the rapid prototyping capabilities of μCLIP opens new avenues for scalable and rapid production in applications such as energy storage, sensors, and lightweight structural components. This work contributes to the evolving landscape of advanced materials and additive manufacturing, offering insights into the synthesis, characterization, and potential applications of 3D printed reduced graphene oxide/polymercomposites.
ContributorsRavishankar, Chayaank Bangalore (Author) / Chen, Xiangfan (Thesis advisor) / Bhate, Dhruv (Committee member) / Azeredo, Bruno (Committee member) / Arizona State University (Publisher)
Created2024
Description
Engineering polymers are critical for contemporary high-performance applications where toughness, thermal stability, and density are at a premium. These materials often demand high-energy processing conditions or highly reactive monomers that hold negative impacts on human and environmental health. Thus, this work serves to remediate the negative impacts of engineering polymer synthesis by addressing toxicity and processing at the monomer level, while maintaining or exceeding previous thermomechanical and stimuli-responsive performance. Polyurethanes (PUs) represent a class of engineering polymers that possess highly modular properties due to the diverse monomer selection available for their synthesis. The efficient reaction between isocyanates and hydroxyls impart stellar properties and flexible processing modalities, however recent scrutiny regarding the toxicity of the isocyanate precursors has driven the search for non-isocyanate polyurethane (NIPU) pathways. The advancement of bis-carbonylimidazolide (BCI) monomers for the synthesis of NIPU thermoplastics and foams is thoroughly investigated in this work. Remarkably, a novel decarboxylation pathway for BCI monomers controlled by catalyst loading enabled in-situ CO2 generation during crosslinking with trifunctional amines, and resulted in a facile synthetic route for NIPU foams. Further explorations into catalyst considerations revealed Dabco® 33-LV as a suitable mechanism for controlling reaction times and careful selection of surfactant concentration provided control over pore size and geometry. This led to a library of flexible and rigid NIPU foams that displayed a wide range of thermomechanical properties. Furthermore, sequestration of the imidazole byproduct through an efficient Michael reaction identified maleimide and acrylate additives as a viable pathway to eliminate post-processing steps resulting in NIPU foam synthesis that is amenable to current industrial standards. This route held advantages over the isocyanate route, as condensate removal drove molecular weight increase and ultimately achieved the first reported phase separation behavior of a NIPU thermoplastic containing a poly(ethylene glycol) soft segment. Furthermore, sustainable considerations for engineering polymers were explored with the introduction of a novel cyclobutane bisimide monomer that readily installs into various polymeric systems. Direct installation of this monomer, CBDA-AP-I, into a polysulfone backbone enabled controlled photo-cleavage, while further hydroxy ethyl functionalization allowed for incorporation into PU systems for photo-cleavable high-performance adhesive applications.
ContributorsSintas, Jose Ignacio (Author) / Long, Timothy E (Thesis advisor) / Sample, Caitlin S. (Committee member) / Jin, Kailong (Committee member) / Arizona State University (Publisher)
Created2024