Matching Items (149)
Description
Organic materials have emerged as an attractive component of electronics over the past few decades, particularly in the development of efficient and stable organic light-emitting diodes (OLEDs) and organic neuromorphic devices. The electrical, chemical, physical, and optical studies of organic materials and their corresponding devices have been conducted for efficient and stable electronics. The development of efficient and stable deep blue OLED devices remains a challenge that has obstructed the progress of large-scale OLED commercialization. One approach was taken to achieve a deep blue emitter through a color tuning strategy. A new complex, PtNONS56-dtb, was designed and synthesized by controlling the energy gap between T1 and T2 energy states to achieve narrowed and blueshifted emission spectra. This emitter material showed an emission spectrum at 460 nm with a FWHM of 59 nm at room temperature in PMMA, and the PtNONS56-dtb-based device exhibited a peak EQE of 8.5% with CIE coordinates of (0.14, 0.27).
A newly developed host and electron blocking materials were demonstrated to achieve efficient and stable OLED devices. The indolocarbazole-based materials were designed to have good hole mobility and high triplet energy. BCN34 as an electron blocking material achieved the estimated LT80 of 12509 h at 1000 cd m-2 with a peak EQE of 30.3% in devices employing Pd3O3 emitter. Additionally, a device with bi-layer emissive layer structure, using BCN34 and CBP as host materials doped with PtN3N emitter, achieved a peak EQE of 16.5% with the LT97 of 351 h at 1000 cd m-2. A new neuromorphic device using Ru(bpy)3(PF6)2 as an active layer was designed to emulate the short-term characteristics of a biological synapse. This memristive device showed a similar operational mechanism with biological synapse through the movement of ions and electronic charges. Furthermore, the performance of the device showed tunability by adding salt. Ultimately, the device with 2% LiClO4 salt shows similar timescales to short-term plasticity characteristics of biological synapses.
ContributorsShin, Samuel (Author) / Li, Jian (Thesis advisor) / Adams, James (Committee member) / Alford, Terry (Committee member) / Arizona State University (Publisher)
Created2021
Description
Over the past three decades, significant progress in the development of organic light-emitting diodes (OLEDs) has been achieved, enabling OLEDs to become a main component in state-of-the-art displays and next generation solid-state lighting. As this technology advances, it is highly desirable to further improve the device efficiency and operational stability to drive the success of OLEDs in future display and lighting applications. This dissertation aims at developing novel organic emitting materials covering visible and near-infrared (NIR) emissions for efficient and table OLEDs. Firstly, a series of tetradentate Pd(II) complexes, which have attractive phosphorescent aggregate emission performance especially at high brightness level in device settings, have been developed. The luminescent lifetime of Pd(II) complex aggregates was demonstrated to be shorter than 1 μs with a close-to-unity photoluminescence quantum yield. Moreover, a systematic study regarding structure-property relationship was conducted on four tetradentate Pd(II) complexes, i.e., Pd3O3, Pd3O8-P, Pd3O8-Py2, and Pd3O8-Py5, featuring aggregate emission. As a result, an extremely efficient and stable OLED device utilizing Pd3O8-Py5 was achieved. It demonstrated a peak external quantum efficiency (EQE) of 37.3% with a reduced efficiency roll-off retaining a high EQE of 32.5% at 10000 cd m-2, and an estimated LT95 lifetime (time to 95% of the initial luminance) of 48246 h at 1000 cd m-2. Secondly, there is an increasing demand for NIR OLEDs with emission spectra beyond 900 nm to expand their applications in biometric authentication, night vision display, and telecommunication, etc. A stable and efficient NIR Pt(II) porphyrin complex named PtTPTNP-F8 was developed, and exhibited an electroluminescent spectrum at 920 nm. By carefully choosing the host materials, an PtTPTNP-F8 based NIR OLED achieved a EQE of 1.9%. Furthermore, an PtTPTNP-F8 OLED fabricated in a stable device structure demonstrated extraordinary operational stability with LT99 of >1000 h at 20 mA cm-2. Lastly, a series of imidazole-based blue Pt(II) complexes were developed and studied. Results indicated that structural modification of ligand molecules effectively tuned the emission spectral wavelength and bandwidth. Two blue complexes, i.e., Pt2O2 P2M and Pt2O2-PPy5-M, emitting at 472 and 476 nm respectively, exhibited narrow-band emission spectra with a full width at half maximum of 16 nm.
ContributorsCao, Linyu (Author) / Li, Jian (Thesis advisor) / Adams, James (Committee member) / Alford, Terry (Committee member) / Arizona State University (Publisher)
Created2021
Description
The purpose of this project was to develop a new questionnaire that was comprehensive and included symptoms of autism and related disorders. 28 parents of children with autism and two adults with autism were interviewed and asked to fill out the questionnaire and rate their child’s symptoms based on the available scale. From their responses, we were able to edit and improve the questionnaire to make it clearer and more concise. We added new symptoms and improved the descriptions of the symptoms listed. The new version of the questionnaire will be edited after interviewing the same 30 people again. After, it will need to be validated by a large study of around 300 people. The questionnaire will be used in an app format and help parents rate their child’s symptoms during clinical studies of medical treatments.
ContributorsFoote, Sophia (Author) / Adams, James (Thesis director) / Duane, Drake (Committee member) / Barrett, The Honors College (Contributor) / Watts College of Public Service & Community Solut (Contributor) / School of International Letters and Cultures (Contributor) / School of Human Evolution & Social Change (Contributor)
Created2022-05
Description
For my thesis I investigated an abnormal gut-derived metabolite of interest identified as 3-(3-hydroxyphenyl)-3-hydroxypropionic acid (HPHPA) that may serve as a potential biomarker for autism, and help us get a better understanding of the underlying mechanisms of this disorder. Currently a laboratory test for autism does not exist, posing severe consequences on individuals with autism. In order to gather research on my metabolite of interest and its connection to autism as well as disorders correlated with autism, I analyzed different pieces of scientific literature investigating HPHPA and compiled this data into a literature review.
ContributorsNawaz, Umar (Author) / Adams, James (Thesis director) / Krajmalnik-Brown, Rosa (Committee member) / Flynn, Christina (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2024-05
Description
Autism Spectrum Disorder (ASD) is an intricate neurodevelopmental disorder characterized by impaired social functioning and communication, repetitive behavioral patterns, and specialized interests (Olesova et al., 2020; Osredkar et al., 2023). Despite the efforts of modern science, the biological origin of ASD is unknown, and no known biomarker for ASD currently exists (Olesova et al., 2020; Osredkar et al., 2023). Indoxyl sulfate has been identified as a toxin associated with ASD and its related symptomology in addition to a number of other conditions, including chronic kidney disease, acute kidney injury, heart failure, Parkinson’s disease, and various mood disorders (Cao et al., 2015; Cassani et al., 2015; Karbowska et al., 2020; Zhao et al., 2013). This article will review what is currently known about indoxyl sulfate in relation to ASD and its comorbidities in an attempt to determine the validity of indoxyl sulfate as a potential biomarker for ASD. Articles for the purposes of this review were collected via Google Scholar, PubMed, and the ASU Library using key words such as “indoxyl sulfate,” “Autism,” and “indican,” and chosen based on relevancy. Through this review, indoxyl sulfate was identified as a potential physiological biomarker for a subset of ASD, with additional research required to verify the findings presented. The identification of a biomarker for ASD could change the current methods of testing for ASD, greatly improving our understanding and treatment of the disorder.
ContributorsHill, Zoë (Author) / Adams, James (Thesis director) / Flynn, Christina (Committee member) / Barrett, The Honors College (Contributor) / College of Health Solutions (Contributor) / Edson College of Nursing and Health Innovation (Contributor)
Created2024-05
DescriptionThis paper studies the potential correlation between succinate levels and ASD. A part of the electron transport chain and the Krebs cycle, succinate has been seen to be potentially relevant to the neurodevelopmental aspects of ASD.
ContributorsKale, Anushka (Author) / Adams, James (Thesis director) / Flynn, Christina (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of Human Evolution & Social Change (Contributor)
Created2024-05
Description
The purpose of this thesis is to analyze in-depth the current research on Autism Spectrum
Disorder (ASD), outlining the prominently researched methods of treatment that have led to
successful therapy for the ones being treated. Within this thesis, the definition of successful
treatment of autistic individuals will be defined by how well the individuals can adapt to their
employment opportunities and their own social lives. Success will be measured through the
effectiveness of specific treatments, such as speech therapy and therapeutic-based diets, to better
gauge the success rate of treatment for autistic individuals. The thesis itself will serve as a review
of the currently proposed treatment methods, analyzing where the most successful treatments
were derived from and then offering a summary conclusion on the overall scope of the research.
Recommendations on future research will be made to encapsulate all the research provided
through which a scholarly lens was applied. Overall, the best methods of treatment will involve
both a dietary and occupational approach, so as to tackle any environmental or genetic origins of
ASD. More specifically, through a combination of vitamin and mineral supplements to manage
behavioral symptoms combined with Applied Behavioral Analysis techniques, ASD can be more
effectively treated to improve an individual’s quality of life.
ContributorsEnriquez, Elias (Author) / Adams, James (Thesis director) / Martin, Thomas (Committee member) / Barrett, The Honors College (Contributor) / School of Politics and Global Studies (Contributor) / Dean, W.P. Carey School of Business (Contributor)
Created2024-05
Description
Pitt-Hopkins Syndrome is not a well-known disorder, and there are not many treatments dedicated to alleviating the severe symptoms that children and adults with Pitt-Hopkins Syndrome suffer through. The purpose of this study is to create questionnaires tailored to Pitt-Hopkins syndrome. With the dearth of Pitt-Hopkins Syndrome research, more knowledge on the disorder and treatments to aid in daily functioning and quality of life can be attained through specialized symptom tracking questionnaires. During this study, the research team designed and finalized two Pitt-Hopkins Syndrome symptom specific questionnaires. Some of the most notable results included the discovery of the most severe symptoms: verbal expression, cognition, social activity, and attention. Additionally, through cross-correlational analysis interrelated symptom clusters that can be targeted for treatment have been discovered.
ContributorsWatkins, Cierra (Author) / Garcia, Kristin (Co-author) / Adams, James (Thesis director) / Kirby, Jasmine (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2024-05
Description
Perovskite solar cells are one of the rising stars in the solar cell industry. This thesis explores several approaches to enhance the properties of the perovskite layer and the solar cell devices in which they operate. They include studies of different antisolvent additives during spin coating of triple cation perovskites, the use of surfactants to improve the quality of perovskite film microstructures, the applicability of a new fabrication process, and the value of post-deposition thermal and chemical annealing processes.This thesis experimentally analyzes different antisolvents, viz., ethyl acetate, isopropyl alcohol, toluene, and chlorobenzene. It focuses on the antisolvent-assisted crystallization method to achieve homogenous nucleation of the perovskite film. Of all the antisolvents, ethyl acetate-treated films gave the best-performing device, achieving a power conversion efficiency of 15.5%.
This thesis also analyzes the effects of mixed antisolvents on the qualities of triple-cation perovskites. Different solution concentrations of chlorobenzene in ethyl acetate and isopropyl alcohol in ethyl acetate are optimized for optimal supersaturation to achieve enlarged perovskite grains. Evaluations are discussed in the context of solution polarity and boiling point of the antisolvents, where 25% chlorobenzene in ethyl acetate antisolvent mixture shows the best film properties.
Another study discusses a new fabrication process called electrical field-assisted direct ink deposition for large-scale printing of perovskite solar cells. This process involves the formation of nanodroplets under an electrical field deposited onto ITO/glass substrates. As a result, smooth Poly (3,4-ethylene dioxythiophene) polystyrene sulfonate layers are
ii
produced with an average effective electrical resistivity of 4.15104 0.26 -m compared to that of spin-coated films.
A successive chapter discusses the studies of the electrical field-assisted direct ink deposition of the photoactive CH3NH3PbI2 (MAPbI3) layer. Its focus is on the post-deposition chemical annealing of the MAPbI3 films in methylamine gas, termed as methylamine gas-assisted healing and growth of perovskite films. This treatment improved the smoothness, reduced porosity, increased density, and generated more uniform grain sizes. Moreover, it improved the inter-grain boundary contacts by eliminating secondary, fine-grained boundary structures. Mechanisms behind the initial liquefaction of the MAPbI3 film's subsequent re-solidification are discussed.
ContributorsGogoi, Banashree (Author) / Alford, Terry (Thesis advisor) / Petuskey, William (Thesis advisor) / Gould, Ian (Committee member) / Li, Jian (Committee member) / Arizona State University (Publisher)
Created2023
Description
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, is the 10th leading cause of death, worldwide. The prevalence of drug-resistant clinical isolates and the paucity of newly-approved antituberculosis drugs impedes the successful eradication of Mtb. Bacteria commonly use two-component systems (TCS) to sense their environment and genetically modulate adaptive responses. The prrAB TCS is essential in Mtb, thus representing an auspicious drug target; however, the inability to generate an Mtb ΔprrAB mutant complicates investigating how this TCS contributes to pathogenesis. Mycobacterium smegmatis, a commonly used M. tuberculosis genetic surrogate was used here. This work shows that prrAB is not essential in M. smegmatis. During ammonium stress, the ΔprrAB mutant excessively accumulates triacylglycerol lipids, a phenotype associated with M. tuberculosis dormancy and chronic infection. Additionally, triacylglycerol biosynthetic genes were induced in the ΔprrAB mutant relative to the wild-type and complementation strains during ammonium stress. Next, RNA-seq was used to define the M. smegmatis PrrAB regulon. PrrAB regulates genes participating in respiration, metabolism, redox balance, and oxidative phosphorylation. The M. smegmatis ΔprrAB mutant is compromised for growth under hypoxia, is hypersensitive to cyanide, and fails to induce high-affinity respiratory genes during hypoxia. Furthermore, PrrAB positively regulates the hypoxia-responsive dosR TCS response regulator, potentially explaining the hypoxia-mediated growth defects in the ΔprrAB mutant. Despite inducing genes encoding the F1F0 ATP synthase, the ΔprrAB mutant accumulates significantly less ATP during aerobic, exponential growth compared to the wild-type and complementation strains. Finally, the M. smegmatis ΔprrAB mutant exhibited growth impairment in media containing gluconeogenic carbon sources. M. tuberculosis mutants unable to utilize these substrates fail to establish chronic infection, suggesting that PrrAB may regulate Mtb central carbon metabolism in response to chronic infection. In conclusion, 1) prrAB is not universally essential in mycobacteria; 2) M. smegmatis PrrAB regulates genetic responsiveness to nutrient and oxygen stress; and 3) PrrAB may provide feed-forward control of the DosRS TCS and dormancy phenotypes. The data generated in these studies provide insight into the mycobacterial PrrAB TCS transcriptional regulon, PrrAB essentiality in Mtb, and how PrrAB may mediate stresses encountered by Mtb during the transition to chronic infection.
ContributorsMaarsingh, Jason (Author) / Haydel, Shelley E (Thesis advisor) / Roland, Kenneth (Committee member) / Sandrin, Todd (Committee member) / Bean, Heather (Committee member) / Arizona State University (Publisher)
Created2019