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2022

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A Novel Framework To Estimate Cognitive Impairment Via Finger Interaction With Digital Devices, Ashley A Holmes, Shikha Tripathi, Emily Katz, Ijah Mondesire-Crump, Rahul Mahajan, Aaron Ritter, Teresa Arroyo-Gallego, Luca Giancardo Jan 2022

A Novel Framework To Estimate Cognitive Impairment Via Finger Interaction With Digital Devices, Ashley A Holmes, Shikha Tripathi, Emily Katz, Ijah Mondesire-Crump, Rahul Mahajan, Aaron Ritter, Teresa Arroyo-Gallego, Luca Giancardo

Faculty, Staff and Student Publications

Measuring cognitive function is essential for characterizing brain health and tracking cognitive decline in Alzheimer's Disease and other neurodegenerative conditions. Current tools to accurately evaluate cognitive impairment typically rely on a battery of questionnaires administered during clinical visits which is essential for the acquisition of repeated measurements in longitudinal studies. Previous studies have shown that the remote data collection of passively monitored daily interaction with personal digital devices can measure motor signs in the early stages of synucleinopathies, as well as facilitate longitudinal patient assessment in the real-world scenario with high patient compliance. This was achieved by the automatic discovery …

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Coping, Affirmation, Resilience, And Empowerment (Care) Program And Its Impact On Depression And Quality Of Life Among Youth Living With Depression In Banjarmasin City, Indonesia : A Mixed-Method Study, Lafi Munira Jan 2022

Coping, Affirmation, Resilience, And Empowerment (Care) Program And Its Impact On Depression And Quality Of Life Among Youth Living With Depression In Banjarmasin City, Indonesia : A Mixed-Method Study, Lafi Munira

Chulalongkorn University Theses and Dissertations (Chula ETD)

Background: The national prevalence of depression among young adults in Indonesia was 29.3% for moderate and 8.0% for severe depression. There are few intervention studies on coping skills training and group cognitive therapy through internet-based intervention for youth living with depression in Indonesia. Objectives: 1) To explore participants’ perception, experience, and cope with depression before and after CARE Program; 2) To investigate effects CARE Program on depression and quality of life among youth living with depression in Banjarmasin City, Indonesia. Method: This study used a convergent parallel mixed method. A qualitative and quasi experimental with two groups pre-post tests among …

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Assessment Of Psychological Impact Of Covid-19 Among Healthcare Professionals In Yangon, Myanmar, Nyein Chan Aung Jan 2022

Assessment Of Psychological Impact Of Covid-19 Among Healthcare Professionals In Yangon, Myanmar, Nyein Chan Aung

Chulalongkorn University Theses and Dissertations (Chula ETD)

Background: Millions of people worldwide have been infected by the Covid-19 pandemic, devastatingly affecting their physical and mental health. During the covid-19 outbreak with the delta variant in 2021, Myanmar experienced its worst healthcare crisis, resulting in work burden, exhaustion, and psychological distress among healthcare professionals. Therefore, the study aimed to determine the psychological impacts of Covid-19 on healthcare professionals in Yangon, Myanmar. Methodology: A cross-sectional study was employed to determine the prevalence and associated factors of Depression, Anxiety, Stress, and Post-traumatic stress disorder (PTSD) among healthcare professionals, who aged 18 and older with at least two years of experience …

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Depolymerization Of Dealkaline Lignin In Co-Solvent System By Electrochemical Advanced Oxidation In A Microreactor, Lalida Waura-Angkura Jan 2022

Depolymerization Of Dealkaline Lignin In Co-Solvent System By Electrochemical Advanced Oxidation In A Microreactor, Lalida Waura-Angkura

Chulalongkorn University Theses and Dissertations (Chula ETD)

Currently, the production of fuels and chemicals heavily relies on non-renewable petroleum oil, which is projected to be depleted by 2050. Lignin is the largest source of renewable aromatic compounds rich in carboxylic and hydroxyl functional groups, thus potentially being used as a renewable alternative for the production of valuable chemicals. In light of aromatic compounds’ recovery from lignin, this work focuses on the efficient depolymerization of dealkaline lignin using the electrochemical advanced oxidation process (EAOP) under ambient conditions in a continuous-flow microreactor system. As hydroxyl radicals generated from water at the anode are the key to the EAOP and …

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Numerical Simulation Study For Carbon Dioxide Sequestration In A Depleted Oil Reservoir, Romal Ramadhan Jan 2022

Numerical Simulation Study For Carbon Dioxide Sequestration In A Depleted Oil Reservoir, Romal Ramadhan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Due to the rise in greenhouse gas concentrations in the atmosphere, one of the most concerning issues at the moment is the climate change. One of the techniques to reduce CO2 emissions, particularly geological storage, is carbon capture and storage (CCS). This study provides the statement of how pressure build-up and CO2 injection rates impact several aspects of CO2 storage, including storage capacity, plume migration, and shut-in time. This study aims to assess the storage capacity of geological formations with different maximum pressure varying from 70% - 90% of fracture pressure to evaluate the formation response to various maximum pressure …

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Development Of Paper-Based Electrochemical Device For Detection Of Biomarker Of Infectious Diseases, Chawin Srisomwat Jan 2022

Development Of Paper-Based Electrochemical Device For Detection Of Biomarker Of Infectious Diseases, Chawin Srisomwat

Chulalongkorn University Theses and Dissertations (Chula ETD)

This dissertation focused on the development of novel point-of-care (POC) testing devices with luminescent and electrochemical detection techniques for the detection of nucleic acid in infectious diseases. This content can be classified into two main parts: (1) the development of a POC sensing device with luminescent detection, and (2) the development of POC testing devices with electrochemical detection. In the first part, an alternating current electroluminescent device for the detection of HIV and HCV cDNA with a label-free platform was developed. The luminosity of the device increased in the presence of the target DNA. The negative charge on the backbone …

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Reductant-Free Ozonolysis Of Alkenes : Acid-Catalyzed Hydration Of Criegee Intermediate, Joshua Osorio Jan 2022

Reductant-Free Ozonolysis Of Alkenes : Acid-Catalyzed Hydration Of Criegee Intermediate, Joshua Osorio

Chulalongkorn University Theses and Dissertations (Chula ETD)

The in-water ozonolysis of alkenes is an emerging alternative method to the conventional ozonolysis since it eliminates the requirement for a reductive work-up step using expensive and hazardous reductants such as dimethyl sulfide, triphenylphosphine, and zinc in acetic acid. Despite its greenness, it still suffers from competing reactions (such as the Baeyer-Villiger reaction and advanced oxidation process) and poor yields of the carbonyl product. Herein, we report the effect of adding an acid as a catalyst in the formation of carbonyl products from in-water ozonolysis. Styrenes and olefinic natural products were dissolved in a mixture of 95:5 (v/v) acetone-water (c.a.[c] …

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Anti-Melanogenic Compounds From Litchi Chinensis Sonn. And Nephelium Lappaceum L. For Cosmeceutical Applications, Junsuda Pimpa Jan 2022

Anti-Melanogenic Compounds From Litchi Chinensis Sonn. And Nephelium Lappaceum L. For Cosmeceutical Applications, Junsuda Pimpa

Chulalongkorn University Theses and Dissertations (Chula ETD)

Melanogenesis is a biosynthetic process that produces the melanin pigment in human skin. Therefore, inhibition of melanin production is crucial for the development of whitening products. Thailand has many fruits processing industry, leading to big amounts of waste from inedible parts such as seeds, peels, and branches. To add value to these waste, this research study aims to investigate their inhibitory effects on melanin in B16F10 melanoma cells and cytotoxicity of eight compounds, shikimic acid (1), proanthocyanidin A-2 (2), δ-tocotrienol (3), and walsurol (4) isolated from Litchi chinensis Sonn and quercetin-3-O-rhamnoside (5), kaempferol-3-O-rhamnoside (6), kaempferol 7-O-α-L-rhamnopyranoside (7), and kaempferol-3-O-β-D-glucopyranosyl-7-O-α-L-rhamnopyranoside (8) …

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Metabolic Alterations For Increased Glycogen And Poly(3-Hydroxybutyrate) Production In Cyanobacterium Synechocystis Sp. Pcc 6803, Nannaphat Sukkasam Jan 2022

Metabolic Alterations For Increased Glycogen And Poly(3-Hydroxybutyrate) Production In Cyanobacterium Synechocystis Sp. Pcc 6803, Nannaphat Sukkasam

Chulalongkorn University Theses and Dissertations (Chula ETD)

Cyanobacteria are a potential biofactory for biopolymer production because they can convert greenhouse gas carbon dioxide and light to useful biopolymers. Synechocystis sp. PCC 6803 is a widely used model cyanobacterium due to its simple genetic information and known biochemistry metabolism. This research aims to develop strategies to increase the accumulation and productivity of biopolymers, poly(3-hydroxybutyrate) (PHB) and glycogen, which are required in current and future industries. Three strategies, namely genetic engineering, metabolic inhibition using chemical treatment, and culture media optimization (regarding nitrogen supply), were studied, as well as their combination to increase the PHB and/or glycogen production. Genetic engineering …

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Catalytic Hydrotreating Of Palm Oil Over Ni/Mesoporous Zeolite For Bio-Jet Fuel Production, Nipitpon Panarmasar Jan 2022

Catalytic Hydrotreating Of Palm Oil Over Ni/Mesoporous Zeolite For Bio-Jet Fuel Production, Nipitpon Panarmasar

Chulalongkorn University Theses and Dissertations (Chula ETD)

The production of bio-jet fuel from palm oil using different types of Ni/mesoporous zeolite. The conventional zeolites were modified into mesoporous zeolites by desilication with NaOH and micro-mesoporous post-synthesis method with SBA-15. Supported Ni-catalysts on zeolites were prepared using a wet impregnation method with a 10 wt% Ni loading. The experiments were conducted in a continuous-flow fixed-bed reactor. The reaction temperature significantly influenced palm oil conversion and the selectivity of jet-fuel range products. The Ni/USY exhibited the highest liquid and jet range selectivity at a temperature of 425°C and a pressure of 25 bar. Furthermore, the modified-support catalyst, 10 wt% …

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Effects Of Articular Knee Injections On Cartilage Of Knee Osteoarthritis Patients And Development Of Rapid Decalcification Method For Articular Cartilage And Subchondral Bone, Pattaranatcha Charnwichai Jan 2022

Effects Of Articular Knee Injections On Cartilage Of Knee Osteoarthritis Patients And Development Of Rapid Decalcification Method For Articular Cartilage And Subchondral Bone, Pattaranatcha Charnwichai

Chulalongkorn University Theses and Dissertations (Chula ETD)

Osteoarthritis (OA) is the most common degenerative joint disease that affects articular cartilage. Intra-articular injection (IA) is one of the treatments that is used to reduce pain and relieve symptoms. Triamcinolone acetonide (TA) and hyaluronic acid (HA) are frequently used in IA injections for OA treatment. Several publications have reported effects of TA, but some of HA, on articular cartilage. Moreover, for histopathological studies, articular cartilage and subchondral bones are commonly used as samples, but the decalcification process is time consuming. Thus, this study aims to compare effects of drugs used in IA injections on cartilage and chondrocytes of osteoarthritis …

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Child Life Student Approaches To And Purposes Of Play, Taylor L. Brower Jan 2022

Child Life Student Approaches To And Purposes Of Play, Taylor L. Brower

Graduate Theses/Dissertations

The aim of this study was to research and gain a greater understanding of what child life students are learning about play. Qualitative data was collected via Qualtrics. Participants reported learning child-led play, structured play, and expressive play as learned approaches to play. Students reported the most learned purpose of play being self–expression, and normalization. Participants provided self-given definitions of the theories and concepts of play as the survey prompted in keeping with the researcher’s goals. The Daisy model in the communication theory Coordinated Management of Meaning provided the theoretical framework, supporting preparation or familiarization, express emotions, process, or cope, …

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Sheltered Cohort: A Restorative Approach To Relational Conflict And Disempowering Policies At A Men’S Homeless Shelter, Shaun A. Sletten Jan 2022

Sheltered Cohort: A Restorative Approach To Relational Conflict And Disempowering Policies At A Men’S Homeless Shelter, Shaun A. Sletten

Graduate Theses/Dissertations

Although homeless shelters provide refuge, they also present several challenges that can negatively affect an individual's sense of internal and external control. A mix-method design was used to explore and address these challenges. Participants (N = 12) were recruited from a men’s homeless shelter via the snowball method. To identify the challenges, in-person, semistructured interviews were conducted. Participants discussed barriers that included being around others who displayed abnormal and deviant behavior, and disparaging policies that censored and restricted basic decision-making processes. Once the challenges were identified, a restorative technique called circles was utilized to increase participants' self-efficacy and satisfaction …

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Enhanced Convolutional Neural Network For Image-Based Steganalysis In Spatial Domain Using Spatial Rich Model And 2d Gabor Filters, Alaaldin Dwaik Jan 2022

Enhanced Convolutional Neural Network For Image-Based Steganalysis In Spatial Domain Using Spatial Rich Model And 2d Gabor Filters, Alaaldin Dwaik

Graduate Theses/Dissertations

During the past decade, many methods have been introduced to handle the image-based steganalysis problem. Traditional steganalysis methods are based on the two-step machine learning mechanism that consists of extracting and classifying phases. Most recent solutions are based on deep convolution neural networks (CNNs), which combine feature extraction and classification in one step. CNN-based steganalysis methods provide superior performance. These CNNs are designed to improve the detection rate by using a set of predefined filters for the pre-processing phase. In this thesis, I propose a CNN model that consists of two convolution layers for pre-processing and features extraction, and four …

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Dot Product Bounds In Galois Rings, David Lee Crosby Jan 2022

Dot Product Bounds In Galois Rings, David Lee Crosby

Graduate Theses/Dissertations

We consider the Erdős Distance Conjecture in the context of dot products in Galois rings and prove results for single dot products and pairs of dot products.

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Intracellular Trafficking And Distribution Of Cd And Inp Quantum Dots In Hela And Ml-1 Thyroid Cancer Cells, Min Zhang Jan 2022

Intracellular Trafficking And Distribution Of Cd And Inp Quantum Dots In Hela And Ml-1 Thyroid Cancer Cells, Min Zhang

Graduate Theses/Dissertations

The study of the interaction of engineered nanoparticles, including quantum dots (QDs), with cellular constituents and the kinetics of their localization and transport, has provided new insights into their biological consequences in cancers and for the development of effective cancer therapies. The present study aims to elucidate the toxicity and intracellular transport kinetics of CdSe/ZnS and InP/ZnS QDs in late-stage ML-1 thyroid cancer using well-tested HeLa cells as a control. The XTT viability assay showed that ML-1 cells, and non-cancerous mouse fibroblast cells, exhibit no viability defect in response to these QDs, whereas HeLa cell viability decreases. These results suggest …

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Elucidating The Role Of Hemodynamic Force In Regulating The Attachment Of Vascular Smooth Muscle Cells (Vsmcs) To Maturing Vessels During Mouse Embryonic Development, Israt Jahan Jan 2022

Elucidating The Role Of Hemodynamic Force In Regulating The Attachment Of Vascular Smooth Muscle Cells (Vsmcs) To Maturing Vessels During Mouse Embryonic Development, Israt Jahan

Graduate Theses/Dissertations

Blood vessel maturation is characterized by the recruitment and attachment of vascular smooth muscle cells (vSMCs) around immature blood vessels, which ultimately form the tunica media. Improper maturation can lead to vascular birth defects ranging from minor birthmarks to lethal brain aneurysms. Previously, our lab demonstrated that hemodynamic force plays an important role to regulate vSMCs recruitment from neighboring low-flow to high-flow vessels followed by the attachment of these vSMCs to the high-flow vessels. To understand the reason for the preferred attachment of vSMCs to high-flow vessels, instead of low-flow vessels, I hypothesize that hemodynamic force modulates the expression of …

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Utilizing Virtual Reality Goggles During Pediatric Laceration Repairs To Reduce Perceived Pain In Pediatric Patients, Emily C. Bozzer Jan 2022

Utilizing Virtual Reality Goggles During Pediatric Laceration Repairs To Reduce Perceived Pain In Pediatric Patients, Emily C. Bozzer

Graduate Theses/Dissertations

In pediatric emergency departments, several providers assess pediatric patients in need a laceration repair, require procedural sedation in order to ensure compliance and complete the laceration repair. This study explored one safe alternative to procedural sedation during pediatric laceration repairs by assessing what pain scores pediatric patients report when undergoing a laceration repair utilizing virtual reality goggles. Pediatric patients ages 6-17 years old perceived pain scores utilizing FACES pain scale was documented. This study found a majority of patients reported lower pain scores during the laceration repair in comparison to their baseline pain score.

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Structural, Electrical And Optical Properties Of Copper Oxide Phase Mixture: An Active Layer Of Solar Cell, Rifat Ara Shams Jan 2022

Structural, Electrical And Optical Properties Of Copper Oxide Phase Mixture: An Active Layer Of Solar Cell, Rifat Ara Shams

Graduate Theses/Dissertations

Both CuO and Cu2O have been well studied and implemented individually as an active layer of a solar cell from early age of manufacturing. A mixture of these two-phase contents at different ratios can bring variance in absorbance which can present new and diverse aspect in solar cell fabrication with added efficiency. Previous works were successful to vary the phase mixture, and the nanostructures provided very high absorption co-efficient but poor optical response on electrical conductivity. The goal of this research is to find out the optimum parameter for the phase mixture of copper oxide with high absorption coefficient as …

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Stress And Its Interventions In Undergraduate College Students During Covid-19, Katie A. Jones Jan 2022

Stress And Its Interventions In Undergraduate College Students During Covid-19, Katie A. Jones

Graduate Theses/Dissertations

Though stress in postsecondary education is a highly researched topic, the emergence of the COVID-19 pandemic has created many new questions that require answers. It is important to connect total perceived stress in undergraduate students with academic, COVID-19, and distance-learning factors and examine the effectiveness of interventions on stress and anxiety during the pandemic. This research determines the efficacy of mindfulness stress interventions (cognitive-behavioral, guided meditation, and music) for individual differences in stress, self- efficacy, and anxiety and links these variables to performance. This study measures levels of different types of stress (total perceived, distance-learning, academic, and COVID-19) for undergraduate …

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Development Of Peg-B-Pla Based Micelles For Neutralization Of A Toxic Peptide, Giselle Campos Jan 2022

Development Of Peg-B-Pla Based Micelles For Neutralization Of A Toxic Peptide, Giselle Campos

Graduate Theses/Dissertations

I herein report the preparation and characterization of PEG-b-PLA block copolymer micelles and PEG-b-PLA/PLA mixed micelles as potential “plastic antidotes” for a toxic peptide, melittin. PEG-b-PLA micelles have been used in a number of biomedical applications for their biodegradability and biocompatibility. Along these lines, I investigated the colloidal stability and the peptide absorption properties of PEG-b-PLA/PLA mixed micelles. A series of PEG-b-PLA block copolymer micelles and PEG-b-PLA/PLA mixed micelles were prepared, and their colloidal stability was studied. The hydrodynamic diameters of stable micelles were determined by using Dynamic …

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Spatial And Temporal Heterogeneity Of Hyporheic Invertebrates In An Ozark Stream, David Fleshman Jan 2022

Spatial And Temporal Heterogeneity Of Hyporheic Invertebrates In An Ozark Stream, David Fleshman

Graduate Theses/Dissertations

The hyporheic zone (HZ), an ecotone between surface water and groundwater in streams, provides extensive but underappreciated habitat for invertebrates in alluvial systems like the gravel-bed streams common in the Ozark highlands. Relative to its importance as a habitat, little is known about spatial distribution and response to disturbance by invertebrates in the HZ. In riffle-pool systems, surface water typically enters the HZ at the head of riffles (downwelling) and returns to the surface at the tail of riffles (upwelling). Previous research has found differences in invertebrate communities and environmental variables between upwelling and downwelling zones, but results have been …

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Effects Of Sex And Reproductive Condition On Behavior Of Southern Red-Backed Salamanders: Activity, Agonistic Behavior And Escape Velocity, Megan N. Mosier Jan 2022

Effects Of Sex And Reproductive Condition On Behavior Of Southern Red-Backed Salamanders: Activity, Agonistic Behavior And Escape Velocity, Megan N. Mosier

Graduate Theses/Dissertations

Producing and carrying eggs is energetically costly and therefore can affect behavior. Female Southern Red-backed Salamanders (Plethodon serratus) in the Ozarks reproduce biennially, and so during the reproductive season some females are gravid and some are non-gravid. In this study, we compared the exploratory and aggressive behaviors of gravid females, non-gravid females, and males, as well as the escape velocities of each sex class. In exploratory trials, sex did not affect distance travelled, but gravid females and males showed shorter latencies to move than non-gravid females during the winter. During the aggression trials, individuals were subjected to a …

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Decomposition And Macroinvertebrate Shredder Colonization Of Autumnal Shed Sycamore Leaves In Mining-Contaminated Streams, Leslie Marie Hatch Jan 2022

Decomposition And Macroinvertebrate Shredder Colonization Of Autumnal Shed Sycamore Leaves In Mining-Contaminated Streams, Leslie Marie Hatch

Graduate Theses/Dissertations

Leaf decomposition in streams is an important ecological function facilitated by bacteria, fungi, and macroinvertebrates. Metal contamination can decrease leaf decomposition rates and reduce macroinvertebrate abundance and diversity. In the current study, I focused on mining-contamination in well-buffered streams in two different Missouri mining districts with varying extents of mining contamination, Big River and Pierson Creek. I measured decomposition rates of sycamore leaves, and abundance and diversity of macroinvertebrate shredders in leaf pack experiments with a full-factorial design to determine the effects of metal contamination of leaves and stream substrates. Comparisons were made between leaf packs upstream and downstream of …

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Synthesis Of Novel Nio/Comn2o4 Heterostructured Nanoparticles And The Effects Of Variable Size And Metal Concentrations On Their Magnetic And Surface Chemical Properties, Farhan Ishrak Jan 2022

Synthesis Of Novel Nio/Comn2o4 Heterostructured Nanoparticles And The Effects Of Variable Size And Metal Concentrations On Their Magnetic And Surface Chemical Properties, Farhan Ishrak

Graduate Theses/Dissertations

I studied the effect of core size and metal concentration on the structural, morphological, and magnetic properties of NiO-based magnetic heterostructured nanocrystals (HNCs) generated hydrothermally. The NiO nanocrystals were created by a thermal decomposition technique, while the surrounding Mn and Co-based phases were created through a hydrothermal procedure, with core diameters ranging from 9.31 nm to 24.51 nm and total metal concentrations of 0.05 M and 0.08 M. The resulting inverted AFM-FiM NiO/CoMn2O4 bimagnetic systems make up the heterostructured nanocrystals. The magnetic HNCs were thoroughly characterized using XRD, SEM-EDX, TEM, PPMS magnetometry, and XPS analysis. Investigations into the structure of …

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Public Perceptions Of Human Physical Interactions, Exhibition, And Conservation Of Tigers And Cheetahs, Abbie Knudsen Jan 2022

Public Perceptions Of Human Physical Interactions, Exhibition, And Conservation Of Tigers And Cheetahs, Abbie Knudsen

Graduate Theses/Dissertations

Tigers and cheetahs are common in the pet trade, public exhibits, and hands-on encounters with the public. Poor regulation of these experiences has resulted in numerous incidents worldwide in which a person was seriously injured or killed by captive big cats. Additionally, concerns for animal welfare have been raised by industry professionals. Prior research on primates has demonstrated exposing people to photographs of cats in different backgrounds can influence their attitudes about animals in captivity, but no study has addressed whether visual images affect human attitudes toward big cats. I used a survey that asked a series of questions about …

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Us Strategic Culture, Homeland Ballistic Missile Defense, And Mutual Vulnerability, Jacob T. Blank Jan 2022

Us Strategic Culture, Homeland Ballistic Missile Defense, And Mutual Vulnerability, Jacob T. Blank

Graduate Theses/Dissertations

Strategic scholars have long understood the indispensable linkage between culture and security policymaking. By shaping the perceptions through which decision-makers formulate security policy, strategic culture analysis adds vital context to the perilously difficult science of understanding and predicting state security outputs. One area where this analytical framework fails to generate the expected result is American missile defense policy. Salient themes of US strategic culture, including an optimistic and problem-solving mindset, positive role of machines, and ahistorical exceptionalism, are reflected in the American way of war – a technologically driven, leadership casualty averse, moralistic, apolitical, and firepower focused enterprise. These factors …

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ผลของนาโนแคลเซียมคาร์บอเนตต่อสมบัติของคอมพอสิตยางธรรมชาติที่พลาสติไซส์ด้วยน้ำมันพืช, กนกภรณ์ เลิศกาญจนาพร Jan 2022

ผลของนาโนแคลเซียมคาร์บอเนตต่อสมบัติของคอมพอสิตยางธรรมชาติที่พลาสติไซส์ด้วยน้ำมันพืช, กนกภรณ์ เลิศกาญจนาพร

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้มีวัตถุประสงค์เพื่อปรับปรุงสมบัติของยางธรรมชาติเพื่อนำไปใช้ในผลิตภัณฑ์ที่ไม่ต้องการสีดำ โดยการเสริมแรงด้วยตัวเติมเสริมแรงทดแทนผงเขม่าดำ ได้แก่ แคลเซียมคาร์บอเนตแบบดั้งเดิม (PCC) และ นาโนแคลเซียมคาร์บอเนต (NCC) ที่มีการควบคุมขนาดและรูปร่างอนุภาค นอกจากนี้ยังต้องการทดแทนพลาสติไซเซอร์จากน้ำมันแร่ (MO) ด้วยน้ำมันรำข้าว (RBO) เริ่มจากผสมยางคอมพาวนด์ที่มีการแปรสัดส่วนของ PCC ที่ 0 10 20 30 40 และ 50 phr เปรียบเทียบพลาสติไซเซอร์น้ำมัน MO กับ น้ำมัน RBO ที่สัดส่วนคงที่ 5 phr ร่วมกับสารเคมีอื่นที่จำเป็นสำหรับการคงรูป ขึ้นรูปเป็นชิ้นงานด้วยการคงรูปที่อุณหภูมิ 160 องศาเซลเซียส จากผลการทดลองพบว่าPCC ที่พลาสติไซส์ด้วยน้ำมัน RBO ให้สมบัติทางกายภาพ สมบัติเชิงกล รวมถึงสัณฐานวิทยาที่ใกล้เคียงกับน้ำมัน MO ดังนั้นน้ำมัน RBO สามารถเป็นพลาสติไซเซอร์แทนน้ำมัน MO ได้ จากนั้นผสมยางคอมพาวนด์ที่มีการแปรสัดส่วนของ NCC ที่ 0 20 40 50 60 และ 80 phr และน้ำมัน RBO ที่สัดส่วนคงที่ 5 phr ร่วมกับสารเคมีอื่นที่จำเป็นสำหรับการคงรูป ขึ้นรูปเป็นชิ้นงานด้วยการคงรูปที่อุณหภูมิ 160 องศาเซลเซียส จากผลการทดลองพบว่าเมื่อเพิ่มปริมาณ NCC ส่งผลให้ปฏิกิริยาการวัลคาไนเซชันของคอมพอสิตยางธรรมชาติเกิดได้เร็วขึ้น เวลายางสกอร์ช (Ts2) และ เวลายางสุก (Tc90) มีแนวโน้มลดลง เนื่องจาก NCC มีอนุภาคขนาดเล็ก พื้นที่ผิวมาก นำความร้อนได้ดี และสามารถกระจายตัวในยางได้สม่ำเสมอ สำหรับสมบัติเชิงกลในด้านแรงดึงพบว่าสัดส่วน NCC ที่เหมาะสมคือ 50 phr มีค่าความทนแรงดึง 27.0 MPa อย่างไรก็ตามเมื่อสัดส่วนของตัวเติมเพิ่มเป็น 60 phr ขึ้นไป ตัวเติมเสริมแรงเริ่มเกาะกลุ่มกันเป็นก้อนส่งผลให้ความทนแรงดึงเริ่มลดลง จากภาพสัณฐานวิทยาพบว่า NCC มีการกระจายตัวในเนื้อยางสม่ำเสมอ ไม่เกิดช่องว่างระหว่างสารตัวเติมกับเนื้อยาง …

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Development Of Screen-Printed Electrochemical Sensor For Determination Of Uric And Oxalic Acids, Anurak Weingkum Jan 2022

Development Of Screen-Printed Electrochemical Sensor For Determination Of Uric And Oxalic Acids, Anurak Weingkum

Chulalongkorn University Theses and Dissertations (Chula ETD)

Uric acid (UA) and oxalic acid (OA) are biomarkers for various biochemical processes and are associated with an increased risk of diseases such as gout, cardiovascular disease, and renal stones. Therefore, the development of sensitive and reliable sensors to monitor the levels of UA and OA is crucial. In this study, we have developed portable and cost-effective electrochemical sensors by utilizing a screen-printed graphene electrode (SPGE). To enhance sensitivity and selectivity, the sensors were modified with bimetallic copper-palladium (Cu-Pd) nanoparticles and monometallic copper (Cu) nanoparticles, along with a molecularly imprinted polymer (MIP). The SPGE modified with Cu-Pd was fabricated through …

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Non-Invasive Wearable Chemical Sensor For Detection Of Sweat Biomarker, Thidarut Laochai Jan 2022

Non-Invasive Wearable Chemical Sensor For Detection Of Sweat Biomarker, Thidarut Laochai

Chulalongkorn University Theses and Dissertations (Chula ETD)

This dissertation focuses on the development of a non-invasive wearable chemical sensor for the detection of sweat biomarkers using electrochemical techniques. This dissertation can be divided into two parts. In the first part, a thread-based electrochemical immunosensor was developed for the detection of cortisol to identify adrenal disorder. The conductive threads were modified with MXene, gold nanoparticles and L-cysteine to increase conductivity and specific surface area for antibody immobilization leading to enhanced sensitivity. To create the cortisol immunosensor, anti-cortisol is immobilized on the modified electrode by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysulfosuccinimide coupling agents. The sensing mechanism is based on the …

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