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Title: ORGANOFUNCTIONALIZED OXOMETALATES: SYNTHESIS, STRUCTURE, AND PROPERTIES OF A NEW CLASS OF MIXED-METAL TETRAMETALATE CLUSTERS
Creator: Shuaib, Damola Taye
Date: 2022
Description: Oxometalates (OMs) are metal-oxide clusters with addenda mental atom mainly V, Mo, and W and bridged by oxide anions. Prototypical examples...
Show moreOxometalates (OMs) are metal-oxide clusters with addenda mental atom mainly V, Mo, and W and bridged by oxide anions. Prototypical examples like polyoxometalates (POMs) are completely inorganic. While clusters with nuclearities ranging from 6 to 18 are common for purely inorganic examples, those with less than nuclearity 6 are rare. Therefore, functionalization by covalent interaction with organic moiety via self-assembly has been utilized as a viable route for making compact clusters with nuclearity of 4 and below. These compounds constitute the organo-functionalized examples of the purely inorganic structure ([XMaOb]n-) POM. Reports of organo-functionalized tetrametalates (TMs), ([MxOyLz])n- (where M = metal, x = 4 and L represents an organic ligand) are sparse. Mixed metal species are especially interesting as potential redox active materials as they contain energetically distinct potential redox centers. OMs have ability to accept electrons in a chemically reversible manner through the terminal oxo-ligand (M=Ot) leading to dπ–pπ electron transfer. Considering the rich structural and electronic properties of these complexes, four neutral mixed-metal (M-V) tetrametalate clusters, [(CoIICl)2(VIVO)2{((HOCH2CH2)(H)N(CH2CH2O))(HN(CH2CH2O)2}2] (1), [(ZnIICl)2(VIVO)2{((HOCH2CH2)(H)N(CH2CH2O))(HN(CH2CH2O)2}2] (2), [CoII2(VIVOF)2{((HOCH2CH2)(H)N(CH2CH2O))(HN(CH2CH2O)2)}2] (3), and [ZnII2(VIVOF)2{((HOCH2CH2)(H)N(CH2CH2O))(HN(CH2CH2O)2)}2] (4) containing unprecedented oxometallocyclic {M2V2X2N4O8}(M = Co, Zn; X = F, Cl) frameworks decorated with diethanolamine ligand in bidentate and tridentate manners. The type of halo-ligand has direct influence on the geometry of the metal M and UV-Vis reflectance spectra revealed changes in electronic structure consistent with charge transfer processes expected. Computational and magnetic properties studies revealed that the ground state multiplicity of 1 is confirmed as an open-shell singlet with a prediction of an isotropic exchange coupling of -6.6 cm-1 but less clear for 2. The vanadium centers are best described as a V(IV) center and the cobalt centers are high-spin Co(II) centers. Less orbital destabilization was observed due to weaker interaction of Cl- ligand on Co than what was observed for O2- ligand on V centers. In 2, there are four weakly coupled spin centers, where the isotropic exchange couplings are defined as J1, J2’, and J2’’. These couplings are approximated as J1 = 1.5/+11.7 cm-1, J2’ = -22.1/-14.8 cm-1, and J2’’ = +4.2/+4.8 cm-1. Although J2’’ is predicted to be weakly ferromagnetic in nature, whereas the fit suggested a weak antiferromagnetic interaction for each of the V(IV)-Co(II) couplings. The low-temperature magnetic susceptibility suggests a Type III spin frustration present in the system. However, competing magnetic interactions are known to be operative in tetranuclear system which is even observed to be more prominent in the mixed-metal tetranuclear system considering the edge-sharing consequence on magnetic behavior. A new route to metal complex synthesis via in situ ligand transformation from diethanolamine to bicine by disproportionation and oxidation reactions yielded three isostructural mononuclear clusters Bis[N,N-bis(2-hydroxyethyl)glycinato]-Cobalt(II) 5, Bis[N,N-bis(2-hydroxyethyl)glycinato]-Nickel(II) 6, and Bis[N,N-bis(2-hydroxyethyl)glycinato]-Copper(II) 7. The observed transformation is predicted to proceed through nucleophilic substitution (SN2) as expected for substituted ammines. These metal complexes are characterized by various analytical techniques such as, FT-IR and UV-Vis spectroscopies, single crystal and powdered X-ray diffraction analyses, Energy-Dispersed X-ray spectroscopy, magnetic properties measurements, thermal gravimetric analysis, bond valence sum calculations etc. Based on their features and detailed structure-property-application analyses, the clusters showed great potentials for catalysis, materials for digital tools, chemical sensing, molecular magnets and precursors as molecular building blocks for extended open frameworks.
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Title: THE IMPACT OF SHARED RECRUITMENT INFORMATION ON APPLICANT OUTCOMES AND THE INFLUENCE OF MODERATING VARIABLES
Creator: Savage, Catherine M.
Date: 2022
Description: Organizations are currently experiencing one of the most challenging environments when it comes to recruiting talent. What started in the...
Show moreOrganizations are currently experiencing one of the most challenging environments when it comes to recruiting talent. What started in the 1990s as the “War for Talent,” in which organizations faced fierce competition when hiring and retaining employees, has persisted, and grown more competitive, post-pandemic. As a result, organizations must re-evaluate their recruitment strategies and find ways to connect with job candidates that will increase the probability that they will pursue open job positions. Thus, we examined how sharing different information regarding pay, diversity statements, and mentoring benefits with 250 potential job applicants, based in the US, may influence their attraction to an organization, perceived person-organization fit, and their intention to pursue the job that was posted. We also examined how ethnicity, gender, and age can influence the job candidates’ perception of the information provided. Results from this research partially supported our hypothesized outcomes. Presenting more information to participants (rather than less) generally had a positive impact on organization attraction and intentions to pursue the position posted in the job advertisement. However, the amount of information shared to participants did not influence perceptions of person-organization fit. Additionally, while ethnicity did not moderate the relationship between amount of information shared and the outcome variables, gender and age were found to influence participants’ reaction to the information provided and their subsequent level of organizational attraction and intention to pursue. Implications and avenues for future research are discussed.
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Title: Control and Operation of Microgrids and Networked Microgrids
Creator: Sheikholeslami, Mehrdad
Date: 2022
Description: This dissertation presents the practical operation and control of microgrids and networked microgrids, particularly, the networked IIT Campus...
Show moreThis dissertation presents the practical operation and control of microgrids and networked microgrids, particularly, the networked IIT Campus Microgrid (ICM) and Bronzeville Community Microgrid (BCM). Microgrids (MGs) provide a potential solution to accommodating renewable and distributed energy resources (DERs). MGs and the networked form of MGs, i.e., networked microgrids or NMGs, have received significant attention in the past two decades. However, several details are often neglected in the literature that need to be considered for the practical operations of MGs and NMGs. First, there is a need for a step-by-step sequence of operations (SOO) that clearly defines the procedures for changing the operation modes of MGs and NMGs for their reliable and resilient operation. Second, there is a need to develop new control strategies for the centralized and distributed control of MGs and NMGs that are resilient to extreme events and are also more sustainable than the ones available in the literature. Third, there is a need for developing the model of MGs and NMGs in a real-time simulator to safely evaluate the performance of the control and operation of MGs and NMGs. Finally, to close the engineering loop, there is a need to connect the digital and physical layers which are known as digital twins. This dissertation proposes solutions for these four requirements and presents results to evaluate the performance of the proposed solutions. First, an SOO is proposed to enable the reliable and safe transition between different microgrid operation modes. The proposed SOO is adaptable to any MG and NMG with minor modifications. Second, for the centralized control, a DER control model is proposed that allows for the regulated power exchange between networked MGs to ensure information privacy and respect the electrical boundary of each MG. For the distributed control, two control schemes are proposed that are resilient to extreme cases, allow the integration of renewable energy resources (RES), and require the minimum intervention of the operators. Third, several techniques are proposed that can be adopted for developing the real-time models of MGs and NMGs. Finally, as a proof of concept, a digital twin of a microgrid with connections between the physical and digital layers is implemented and tested. The IIT Campus Microgrid (ICM) and Bronzeville Community Microgrid (BCM), as well as their networked form (networked ICM-BCM), are selected as the practical testbeds and are modeled in Real-time Digital Simulator (RTDS). The RTDS model is interfaced with microgrid master controllers (MMC) for real-time data exchange and the performance of the MMCs and the distributed control strategies are tested to illustrate the importance of adopted methods in the real-time control of MGs and NMGs. Finally, a proof of concept for the digital twin of ICM is presented.
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Title: ELECTROSPUN SILKWORM SILK FIBROIN - INDOCYANINE GREEN BIOCOMPOSITE FIBERS: FABRICATION, CHARACTERIZATION AND APPLICATION TOWARDS HEMORRHAGE CONTROL
Creator: Siddiqua, Ayesha
Date: 2022
Description: Silk fibroin (SF), a structural protein found in the Bombyx mori cocoons has gained attention in several biomedical applications as tissue...
Show moreSilk fibroin (SF), a structural protein found in the Bombyx mori cocoons has gained attention in several biomedical applications as tissue engineering scaffolds and wound dressings owing to its properties such as biocompatibility, water vapor permeability and biodegradability. Indocyanine Green (ICG) is an FDA approved tricarbocyanine dye used in medical diagnostics due to its unique photothermal and fluorescent properties. Electrospinning is a highly efficient, easy, and inexpensive technique used to generate nanometer to micrometer thick fibers. In this study, SF and ICG were co-spun to generate flexible microfibers with high surface area to volume ratios. Pure silk, SF-ICG (0.1%) and SF-ICG (0.4%) were chosen for the purpose of this study. Since, as-spun fibers are unstable in aqueous solutions, post treatment methods were explored to enhance the durability of the fibers and to minimize ICG leaching. It was found that ethanol vapor treatment (EVT) not only induced β-sheet formation in SF but also improved the SF-ICG interaction thereby reducing ICG leaching from the composite fibers. Ethanol vapor treated SF-ICG fibers showed less ICG leaching than liquid ethanol treated (LET) SF-ICG fibers indicating the efficacy of the EVT. The increase in SF solution viscosity with ICG concentration suggested a strong silk-ICG interaction which was further confirmed by DSC. The 1h water uptake and the three-day mass loss experiments indicated that the fibers are stable and highly absorbent material. Heat evolution was evaluated by measuring the temperature change in water of a fixed volume after irradiation with a 500 mW, 808 nm diode laser. The heat evolved by the flat fiber scaffolds was higher than the 3D fiber balls, indicating improved light penetration in the former. Pure silk produced negligible heat and it was used as a control. With 14.9 W/cm2 irradiation, the post-treated SF-ICG (0.4%) 3D fibrous ball of 2-3 mg dry weight, solidified a drop of bovine blood in 40 s. In contrast, a single layer fiber matrix required 3 min. to achieve the same clotting effect. Fibers folded into flat scaffolds were able to solidify a blood drop in 25 s. Pure silk fibers in all the cases showed negligible change after irradiation. The results suggest that a larger contact area of fibers is desirable for faster blood clotting, and EVT prompted better ICG retention in SF fibers. Based on the above results, SF-ICG (0.4%) fibers were utilized in a device developed to mimic blood flowing at a rate of 0.5 mL/h through a damaged blood vessel. It was found that irradiation of SF-ICG locally placed at the “damage” region effectively stopped “bleeding” whereas irradiated pure silk was unable to control the blood flow, which demonstrated the success of our SF-ICG fibers towards hemorrhage control.
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Title: WHAT IMPACT DO NUMBER TALKS HAVE ON ELEMENTARY CLASSROOM MATHEMATICAL DISCOURSE AND STUDENT AND TEACHER ATTITUDES TOWARD MATHEMATICS?
Creator: Sleezer, Meghan V
Date: 2021
Description: Number Talks, created in the early 1990s by Ruth Parker and Kathy Richardson, have gained popularity in the mathematics education community...
Show moreNumber Talks, created in the early 1990s by Ruth Parker and Kathy Richardson, have gained popularity in the mathematics education community over the past decade with the publication of the book series Number Talks (Parrish, 2010, 2014), and especially since the publication of Making Number Talks Matter (Humphreys & Parker, 2015). All in all, the authors contend Number Talks can bring joy into the classroom (Humphreys and Parker, 2015, p. 6), improving student attitudes about mathematics and ultimately allowing for a more productive disposition. The characteristic that separates Number Talks from other pedagogical tools is the disconnectedness from the rest of the lesson: Number Talks need not build up to or build upon the day’s objective. Thus, what the authors argue is that the activity of Number Talks itself – albeit disconnected from the day’s objective – improves all of the aforementioned skills, regardless of what occurs during the remainder of each class session.Eight teachers from five different Chicago-area private grade schools implemented Number Talks in their 3rd-5th grade classrooms for four to six weeks in the early part of the year 2020. Student attitudes toward mathematics and toward mathematical discourse were assessed by way of survey and classroom observation before and after implementation. Classroom interactions and levels of mathematical discourse during the normal class time (outside of the Number Talk session) were assessed before and during implementation. No significant changes (positive or negative) relating to any measure were found. Teachers noticed that students who enjoyed math before the implementation also enjoyed Number Talks, while students who struggled with math were mostly disenchanted with Number Talks. Future research includes exploring whether tailoring Number Talks to relate to the upcoming lesson improves the positive effects advertised by the authors. Teacher professional development related to ambitious teaching practices (NCTM, 2017) and growth mindset (Boaler, 2016b) may complement the use of Number Talks to result in improved attitudes and discourse.
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Title: Do Numeric Performance Ratings Have Any Merit?
Creator: Sanders, Emily Kathleen
Date: 2022
Description: Numeric performance ratings have been a component of performance evaluation for decades (Prowse & Prowse, 2009; Pulakos, Mueller-Hanson & Arad...
Show moreNumeric performance ratings have been a component of performance evaluation for decades (Prowse & Prowse, 2009; Pulakos, Mueller-Hanson & Arad, 2019). Yet, in recent years their necessity has been questioned (Adler, Campion, Colquitt, Grubb, Murphy, Ollander-Krane, & Pulakos, 2016), with some organizations going so far as to remove numeric ratings entirely (Capelli & Tavis, 2016; Rock, Davis & Jones, 2014; Burkus, 2016). Unfortunately, this practice has been largely unexamined in an empirical manner. The present study tested whether the claim – that numeric ratings do not matter – holds up in all cases. This is done by exploring whether the presence or absence of numeric ratings, impacts employee perceptions of fairness associated with the appraisal. As numeric ratings are argued to be a mechanism for communicating a fair, standard, and consistent practice, the study aimed to understand if the mere presence of numeric ratings may offset some of the negative reaction employees have toward performance appraisal when they have poor-quality relationships with their supervisors. Findings indicated that while employee-manager relationship quality (assessed via Leader-Member Exchange) has a direct relationship with perceptions of fairness associated with the appraisal, the presence of numeric ratings did not moderate this relationship. Practical implications and future research recommendations are discussed.
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Title: Stimulation-Responsive Materials for the Treatment of Disordered Tissues
Creator: Clutter II, Elwin Dean
Date: 2022
Description: Microenvironments offer physical and chemical cues to cells that affect their behavior. These cues can be bioactive chemicals such as drugs...
Show moreMicroenvironments offer physical and chemical cues to cells that affect their behavior. These cues can be bioactive chemicals such as drugs and cytokines, matrix cues like stiffness and composition, and electrical signals as seen in membrane potentials and epithelial wound healing. Controlling these cues can drive cell behavior toward apoptosis, proliferation, or changes in protein expression. In this thesis research, three components were used to model changes in cell behavior: the near infrared dye indocyanine green (ICG), silk fibroin (SF) from Bombyx mori silkworm cocoons, and carbon nanotubes (CNT). The mechanism of ICG photobleaching was studied for the efficacy to kill neuroblastoma cancer cells. ICG was twice as effective at killing neuroblastoma than fibroblast cells. Albumin stabilized monomeric ICG to enhance photobleaching by improving light interaction, and photodegradation of ICG into α,β-unsaturated aldehydes led to significant reduction of proliferation in neuroblastoma cells by targeting cell signaling components such as protein transcription factors. SF-ICG composite materials were developed into films and electrospun fibers. These composite materials were examined as light-activated wound coverings to control bleeding in hemorrhage, using ICG’s photothermal effect. ICG added an absorbance peak to SF at 805 nm. Irradiation decreased this peak, produced a new absorbance peak at 352 nm, and an increased fluorescence peak around 490 nm, showing photochemical changes that may be useful in sensor design. Increased heat production from irradiation of SF-ICG occurred in the films with 0.2% w/w ICG in SF during 1 min irradiation, whereas SF-ICG fibers required improvement of processing by ethanol vapor treatment (EVT) to reduce loss of ICG during preparation. EVT improved ICG retention in SF fibers during sterilization with 70% ethanol solution thus improving heat generation in the SF-ICG fibers. Heat evolved from SF-ICG 0.2% film solidified bovine blood within 42 s, with visible changes after the first 6 s. SF electrospun fibers were investigated to optimize silk preparation to reduce diameters and increase alignment to mimic local native cell environments with and without CNT to add conductivity for enhancement of electrical stimulation. CNT reduced SF fiber diameters below 1% and effected alignment differently as the concentration increased. Longer degumming times decreased SF fiber diameters and alignment of the same concentration. The optimized conditions were 1 h degumming time with 1.5 ml/h flow rate at a concentration of 100 mg/ml spinning solution with 0.25% CNT to form fibers with 1.36 (± 0.09) µm diameter and 0.31 (± 0.01) a.u. alignment. Additionally, SF fibers were used as a long-term cell growth scaffold to compare with decellularized native tissue. Decellularized tissue decreased fibroblast mRNA expression of collagen type 1, lysyl oxidase-like 1 and matrix metalloproteinase 9, while all other genes expression was the same as cells on plastic. The SF fiber scaffold reduced fibroblast expression of collagen type 3 compared to growth on plastic, and both collagen types 1 and 3 increased over growth time on SF. Immunofluorescence staining showed both collagens newly deposited on the SF scaffold and improved over time. In conclusion, proteins stabilized ICG monomers to improve light interaction, efficacy of photobleaching, and heat evolution to induce apoptosis in neuroblastoma and agglutination of blood in SF composites. Irradiation of ICG enhanced changes in optical properties and may have sensor applications. The decrease of genes may be due to each scaffold having lower stiffness compared to plastic. ICG and SF are both materials with applications as biological scaffolds in pelvic organ prolapse and treatment of neuroblastoma and hemorrhage.
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Title: SOLID-STATE SMART PLUG DEVICE
Creator: Deng, Zhixi
Date: 2022
Description: Electrical faults are a leading cause of residential fire, and flexible power cords are particularly susceptible to metal or insulation...
Show moreElectrical faults are a leading cause of residential fire, and flexible power cords are particularly susceptible to metal or insulation degradation that may lead to a variety of electrical faults. Smart Plugs are a type of plug-in device controlling electrical loads via wireless communication for consumer market. However, there is lack of circuit protection features in existing Smart Plug products. Moreover, there is no previous product or research on Smart Plug with circuit protection features. This thesis introduces a new Smart Plug 2.0 concept which offers all-in-one protection against over-current, arc, and ground faults in addition to the smart features in Smart Plug products. It aims at preventing fire and shock hazards caused by degraded or damaged power cords and electrical connections in homes and offices. It offers microsecond-scale time resolution to detect and respond to a fault condition, and significantly reduces the electrothermal stress on household electrical wires and loads. A new arc fault detection method is developed using machine learning models based on load current di/dt events. The Smart Plug 2.0 concept has been validated experimentally. A 120V/10A solid-state Smart Plug 2.0 prototype using power MOSEFTs is designed and tested. It has experimentally demonstrated the comprehensive protection features against all types of electrical faults.
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Title: Fatigue Life Prediction for Structures with Interval Uncertainty
Creator: Desch, Michael R.
Date: 2022
Description: A new method for reliable fatigue life prediction in metal structural components is developed where uncertainties are quantified using...
Show moreA new method for reliable fatigue life prediction in metal structural components is developed where uncertainties are quantified using interval variables. Using this crack-initiation-based method, first, the uncertainties in laboratory test data for the fatigue failure of a structural detail are enumerated. This uncertainty quantification is performed through an interval-based enveloping procedure that relates the interval stress ranges to the number of cycles to failure, leading to the construction of an interval S-N relationship. Next, the uncertainties in field test data are enumerated in the extremum values of each stress range, as intervals, leading to the construction of interval stress ranges. For both the laboratory and field data uncertainty analyses, the mean stress effects are considered. Next, the interval damage accumulated over the duration of the field data is determined using the constructed interval S-N relationship and the obtained interval stress ranges. Then, the interval existing damage and interval remaining life are determined. Finally, as a conservative measure, the minimum remaining fatigue life is obtained in which all uncertainties are considered. Three numerical examples illustrating the developed method are presented, and the results are compared with results obtained by both Monte Carlo simulation and optimization. Using this method, for the numerical examples considered, it is shown that the results for bounds on the existing damage and the remaining fatigue life are sharp. Moreover, due to its set-based approach, the method is significantly more computationally efficient when compared with iterative procedures.
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Title: Stress-Induced Habitual Responding as a Maintenance Factor in Bulimia Nervosa Spectrum Disorders
Creator: Dougherty, Elizabeth Nash
Date: 2022
Description: Individuals with bulimia nervosa spectrum disorders often compulsively engage in binge eating and purging, despite life threatening...
Show moreIndividuals with bulimia nervosa spectrum disorders often compulsively engage in binge eating and purging, despite life threatening consequences. Little is known about factors that contribute to compulsivity in these conditions. The purpose of this study was to investigate whether stress and habitual control over bulimic behaviors play a role in maintaining symptoms in these disorders, using ecological momentary assessment. Women with bulimia nervosa spectrum disorders (N = 81) completed self-report baseline questionnaires and a 14-day EMA protocol which involved daily assessments of stress, negative affect, bulimic behaviors, and contextual antecedents to bulimic behaviors. The results indicated that baseline habitual control over binge eating and purging were not associated with global eating pathology or eating disorder-related clinical impairment. However, exploratory analyses revealed that habitual control over binge eating and purging were associated with more frequent engagement in these behaviors during the previous four weeks. Neither stress appraisal nor stressor frequency were associated with habitual control over bulimic behavior during the EMA period. In terms of affect trajectories surrounding bulimic behaviors, negative affect increased in the hours leading up to these behaviors, decreased in the hours following these behaviors, and was higher immediately after these behaviors compared to before. Habitual control over binge eating and purging did not moderate temporal relations between negative affect and bulimic behaviors during the EMA period. Overall, the findings suggest that habit may play a role in maintaining binge eating and purging.
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Title: ENGAGEMENT FRAMEWORK FOR SERIOUS THERAPEUTIC GAMES FOR HEALTH
Creator: Damarjian, Alex G.
Date: 2022
Description: The conventional treatment of amblyopia in pediatric patients routinely experience low patient compliance due toits limitations. Therapeutic...
Show moreThe conventional treatment of amblyopia in pediatric patients routinely experience low patient compliance due toits limitations. Therapeutic games that utilize VR technology have the potential to open new avenues of medical research and treatment. A review of the prevailing literature shows the effectiveness of VR based games for therapeutic applications and the potential for increased patient compliance. A strong component of the literature is grounded in the medical humanities, specifically the way in which thought patterns, cognitive development, and perceived social rejection affect patient engagement and treatment efficacy. In order to increase the effectiveness of therapeutic games and streamline their development, a new framework has been created using existing research into therapeutic games. This framework ensures that all therapeutic games meet certain criteria within ethics, immersion, active learning, universal accessibility, aesthetics, and medicine. When applied to game development, specifically virtual and extended reality games, it can be used to transform existing therapeutic or diagnostic models into games operating as health care tools. The result is a more effective, lower cost, more accessible treatment option with increased patient compliance and greater overall outcomes.
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Title: Effect of heat treatment on microstructure and electrochemical behavior of laser powder bed fusion hydride- dehydride ti-6al-4v alloy
Creator: Delpazir, Melody Honardan
Date: 2022
Description: In powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While...
Show moreIn powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While numerous studies have evaluated 3D-printing of spherical powder, very limited research has been carried out on the processing of the non-spherical feedstock. This study is targeted specifically to the use of non-spherical Ti-6Al-4V powders in the laser powder bed fusion (L-PBF) process. Two different post-heat-treatments including hot isostatic pressing and solution treatment are applied. The microstructure evaluation, potentiodynamic polarization, and electrochemical impedance spectroscopy methods are used to characterize L-PBF processed and post- treated specimens. Though as-built part exhibits anisotropic microstructure containing acicular α′ martensite with trace amount of β phase, the heat-treated parts are composed of α+β in which length and thickness of the α-lath depends on the treatment. The below β transus heat treatment leads to the formation of a homogenized grain structures composed of α+β. Electrochemical results show that the below β transus heat-treatment had a slight positive effect on the improvement of corrosion resistivity (corrosion rate of 4.2×10-6 mmy- 1 , which is classified as an excellent ) compared to other conditions, which would be associated to the natural excellent corrosion resistance of Ti-6Al-4V alloy. This slight improvement can be ascribed by the slightly faster formation of a passive layer and its enhanced efficiency because of the presence of the fine-structured β phase in post heat- treated L-PBF processed Ti-6Al-4V alloy.
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Title: DOES FAMILY QUALITY OF LIFE MEDIATE THE RELATION BETWEEN AUTISM WAIVER SERVICES AND CHILD PROGRESS?
Creator: Desai, Shivani S.
Date: 2022
Description: Autism Spectrum Disorder (ASD) is a pervasive neurodevelopmental disorder that affects a child’s language, social, and behavioral development,...
Show moreAutism Spectrum Disorder (ASD) is a pervasive neurodevelopmental disorder that affects a child’s language, social, and behavioral development, and also is associated with difficulty with academics, independent completion of daily living skills, and emotion regulation. Diagnosed individuals often require comprehensive, long-term, and family-based intervention that is costly. Several states, including Maryland, have adopted Medicaid Home and Community Based Services (HCBS) waiver services that specifically serve children and young adults with ASD at no out-of-pocket cost to families. The Maryland autism waiver (AW) also includes services to support diagnosed individuals’ family members, including family consultation and respite services. Family factors, such as specific parenting behaviors and parental mental health, contribute significantly to symptom improvement in children with ASD and child development more broadly, highlighting the importance of studying family systems and targeting them in treatment. Prior research has found that AW services have a positive impact on family quality of life (FQoL), which is a multidimensional concept of family functioning. The aim of the present study was to examine if the several domains of FQoL are mediators in the relation between receipt of Maryland HCBS AW services and caregivers’ perception of their child’s improvement in several domains of functioning. The participants in this study consisted of 460 families who were enrolled in a larger study examining effects of Maryland AW services. Half of these families (n = 230) received the Maryland Medicaid AW services (n = 230) and the other half were on a registry to receive services (n = 230). Deidentified survey data were collected between 2013-2016 from caregiver informants who had a child under the age of 21 who exhibited symptoms of ASD. The survey included questions about demographics, FQoL, and their child’s progress in the areas of academics, independent living skills, social communication skills, stereotypic and repetitive behaviors, and aggressive behaviors over the past 6 months. Results of the mediation analyses revealed that FQoL in the domains of parenting, emotional well-being, and disability support services (but not in the domains of family interaction and physical/material well-being) each mediated the relations between AW services and caregiver report of improvement in all measured domains of child functioning (academics, independent living skills, social communication skills, stereotypic and repetitive behaviors, and aggressive behaviors). These findings highlight the significant role of FQoL as a mediator in the relation between waiver serves and child outcome. They also reveal the importance of increasing family quality of life when providing treatment services to children with symptoms of autism and their families.
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Title: WIDE BANDGAP FRACTIONAL POWER PROCESSING
Creator: Kundu, Aritra
Date: 2022
Description: The adoption of wide bandgap (WBG) power semiconductors can improve the performance of power converters at the expense of significantly higher...
Show moreThe adoption of wide bandgap (WBG) power semiconductors can improve the performance of power converters at the expense of significantly higher cost than Si at present time. In this thesis, an innovative Wide bandgap Fractional Power Processing (WFPP) design concept is introduced where silicon devices process the base power at a low switching frequency (2kHz or lower) while WBG devices are judiciously used to process only a fraction of the total power at a much higher frequency (tens of kHz). WFPP inverter is a design concept that splits the power processing into a low frequency Si base power processor and a high-frequency WBG fractional power processor. WBG devices are therefore judiciously used to process only a fraction of the total power to achieve both high-efficiency and lower cost than a full-WBG converter design. This thesis investigates an optimization strategy to minimize the total power loss while maintaining a reasonable THD and cost for a hybrid inverter design with comprehensive power loss analysis and calculation on fundamental and harmonics currents. Optimal selection of power sharing between the Si and WBG inverters and switching frequency are discussed in the thesis. The circulating current paths in topology with hybrid switching frequencies are also analyzed and presented in this thesis. Experimental results on a 9kW SiC/Si hybrid inverter prototype with isolated and non-isolated DC power supplies are presented to validate the design concept.
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Title: STRUCTURE AND DYNAMICS OF MODIFIED NUCLEOSOMES UNDER EPIGENETIC REGULATION
Creator: Kohestani, Havva
Date: 2022
Description: Epigenetic regulations are critical in inducing heritable phenotype changes in biological systems without alternating their core genetic DNA...
Show moreEpigenetic regulations are critical in inducing heritable phenotype changes in biological systems without alternating their core genetic DNA sequences. In vivo, reversible epigenetic mechanisms engage various molecular structures from RNAs to larger proteins. The present thesis investigates the influence of epigenetic regulatory factors such as histone protein variants and small non-coding RNAs on the dynamics and structure of nucleosome core particles. Our results show that a histone substitution is an efficient tool in increasing or decreasing the exposure of DNA to post-translational modification (PTMs) factors or larger molecular assembly elements. Substitution of canonical H2A with H2A.B alters DNA-dimer interface resulting in increased breathing and accessibility of DNA. Replacement of canonical H3 with CENP-A variant impacts the overall core-DNA dynamics with flexibility of DNA entry/ exit sites and more rigid tetramer structure. Histone substitution also affects the micro to macro level molecular communication in the nucleosome system. The long-range correlated motions are weakened in H2A.B compared to canonical NCP. We observed a reduction in effective long-range DNA-DNA and DNA-core allosteric pathways in CENP-A NCP compared to canonical and Widom NCPs. Non-coding RNAs increase the tendency of the H3 tail histones to interact with DNA and induce the structural changes in the initial ideal B-DNA of NCP. Overall, the interaction of epigenetic regulatory factors in the form of protein or nucleic acids shifts the energetic and structural properties of the original nucleosome system. As a result, the chromatin structure is prepared to generate the proper biological response throughout spermatogenesis, chromosome segregation, or PTMs assembly.
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Title: Keeping the Spark Alive: Examining Associations Between Technology Use For Cybersex, Health and Relationship Satisfaction In Long-Distance Relationships
Creator: Khan, Humza
Date: 2022
Description: Background: Technology is important to many romantic relationships, especially long-distance relationships (LDR), insofar as technology can...
Show moreBackground: Technology is important to many romantic relationships, especially long-distance relationships (LDR), insofar as technology can minimize the impact of the lack of proximity that is characteristic to LDR. Cybersex, a specific use of technology within romantic relationships, is associated with increased relationship satisfaction among partners in proximal relationships. Cybersex also relates to health broadly, and to anxiety and depression specifically, with mixed associations. Despite LDR lending themselves to cybersex, associations between cybersex, relationship satisfaction, and health have not been studied in LDR. This study has three aims: (1) to provide the first descriptive data related to cybersex behavior, relationship satisfaction and health in LDR; (2) to examine associations between cybersex behaviors and relationship satisfaction, and cybersex and health in LDR; and, (3) to test whether biological sex moderates cybersex-relationship satisfaction and cybersex-health associations among those in LDR. We predicted that cybersex behaviors would relate positively to relationship satisfaction for both males and females, although we predicted males would report stronger associations than females. We predicted cybersex behaviors would relate positively to health for both males and females, although we predicted females would report weaker associations than males. Methods: Participants (N = 146; 18 years or older; English speaking; in LDR for 3+ months) completed a paid online survey on relational experiences and health/well-being. Cybersex behaviors were assessed through an internally created “sex and cybersex behaviors” scale. Relationship satisfaction was assessed via the Couples Satisfaction Index (CSI). Both broad health, and anxiety and depression, were assessed with the PROMIS-29. Correlations were assessed between key study variables. Regression analyses were used first to test associations between cybersex and relationship satisfaction, then cybersex and health, and finally, the moderation effect of biological sex in these associations. Results: The average member of our sample was White, college aged, had no children, a full-time undergraduate student and low SES. Correlation analyses show significant correlations between core study variables (relationship satisfaction, global health, cybersex behavior, depression & anxiety) at some level. Sex-level analyses show that when compared to males, females reported significantly higher average anxiety scores, and more texting sex behavior. Linear regressions established cybersex behavior as a negative predictor of global health and a positive predictor of depression and anxiety, but not relationship satisfaction. Moderation analyses indicated that biological sex moderated the cybersex behavior-global health association such that more cybersex behavior negatively predicted global health for males but not females. Discussion: These differences among sexes and health in LDR observed within our findings may be explained by the social role theory, in which females have worse health than males however, males having worse overall physical health than females may be due to a lack of copresence from their partner. In addition, females engaging in higher levels of texting cybersex may be related to sociocultural factors. Conclusion: Overall, our study contributes to the understanding of cybersex behavior, relationship satisfaction and health outcomes by among males and females in LDR. Our findings suggest that this sample of LDR females engage in more texting cybersex, have higher anxiety symptom severity, and have equal levels of relationship satisfaction.
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Title: Efficacy of Organic Acid Treatments for the Reduction of Listeria Monocytogenes on Hard Boiled Eggs
Creator: Khouja, Bashayer
Date: 2022
Description: Ready-to-eat hard-boiled eggs (HBEs) are a popular and convenient choice for consumers and food servicers. Recentrecalls of hard-boiled eggs...
Show moreReady-to-eat hard-boiled eggs (HBEs) are a popular and convenient choice for consumers and food servicers. Recentrecalls of hard-boiled eggs have highlighted the susceptibility of contamination with Listeria monocytogenes. HBEs are generally treated with antibacterials to ensure the safety and quality of the product. While citric acid is often used, research has determined it is not effective in some situations; therefore, the assessment of additional organic acids is necessary. This study examined the efficacy of acetic, lactic, and malic acid on the reduction of L. monocytogenes on HBEs after a 24- hour treatment trials and 28 days storage trials. Fresh eggs were cooked in boiling water, peeled, and stored at 4°C for 24h before use. For treatment trials, HBEs were dip- inoculated with a 4-strain cocktail of rifampicin resistant L. monocytogenes, resulting in 8 log CFU/egg. Following air drying, hard-boiled eggs were treated at 5 or 25°C with 2% acetic, lactic, or malic acid. L monocytogenes populations were enumerated in intervals up to 24h by homogenization of HBEs with BLEB and cultivation on BHIrif. For pre- treatment storage trials, HBEs were first dip- inoculated with a rifampicin- resistant 4- strain L. monocytogenes cocktail for 20 min, resulting in 1 log CFU/egg, air dried for 10 min, followed by treatment with 2% acetic, lactic, or malic acid for 24 h at either 5 or 25°C. For post- treatment inoculation trials, HBEs were first soaked in 2% acetic, lactic, or malic acid for 24 h at either 5 or 25°C, air dried for 10 min, spot-inoculated at 1 log CFU/egg, and then dried for 20 min. All HBEs were individually stored in bags at 5°C for up to 28 days. The presence of L. monocytogenes was determined at intervals during storage by enrichment with BLEB on BHIrif and Brilliance Listeria Agar. Triplicate eggs were assessed for each timepoint, and three independent trials were conducted. Data were analyzed by Student’s T-test, ANOVA, and Fisher’s exact test, p≤0.05. The initial inoculation level of L. monocytogenes on HBEs was 8.27±0.37 log CFU/egg. After 24 h treatment, all L. monocytogenes populations were significantly reduced on HBEs. At 5°C, populations were reduced by 3.15±0.70, 3.46±0.02, and 4.78±0.23 log CFU/egg. Compared to 5°C, a significantly higher population reduction occurred with acetic and lactic acid when treatment occurred at 25°C. The inactivation of L. monocytogenes on HBEs for the storage trials was associated with the order of the contamination: pre-or post-the acid treatment. Prior storage, L. monocytogenes was detected on 100% of the HBEs. Malic acid pre-treatment was significantly effective in eliminating L. monocytogenes on HBEs at 5 and 25°C, while acetic acid was effective only at 5°C. All acids did not eliminate L. monocytogenes in the case of post-treatment contamination at any tested temperature. The results of this study aid in understanding the efficacy of organic acid treatments against L. monocytogenes on HBEs. Results are useful in the development of preventive controls and guidelines to ensure the safety of HBEs.
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Title: ANALYTICAL APPROACH TO ESTIMATE ROTOR TEMPERATURE IN SWITCHED RELUCTANCE MOTOR
Creator: Koujalagi, Shweta Manohar
Date: 2022
Description: Motors contribute most of the loads. Motors find major applications in automobile industries, household appliances, industrial equipment, and...
Show moreMotors contribute most of the loads. Motors find major applications in automobile industries, household appliances, industrial equipment, and other areas. With the time, engineers and industries found some of the drawbacks or disadvantages of using induction motors in certain applications. They started developing other types of motors that are more efficient than existing ones. Among those, switched reluctance motor, referred as SRM is the one. SRMs are simple in construction, rugged and highly efficient motors.Even though SRM has higher efficiency, it still contribute some losses in the form of heat which will increase the temperature of SRM. If the temperature increases beyond certain limit, cable insulation fails, degrades rotor capability of aligning characteristics, damages bearings, etc. Therefore, it is important to understand the flow of heat in SRM. This thesis focuses on heat transfer analysis from stator coil to rotor of SRM using analytical method and numerical method such as finite element analysis from available coil temperature without using any kind of sensors. Analytical and FEA models are built separately to obtained rotor temperatures at various coil temperatures and rotor speeds. Finally, analytical results are validated with FEA model results. Therefore, once the rotor temperature is estimated accurately, model can be implemented in automotive and other industrial applications to continuously monitor the rotor temperature. It is important to monitor temperature to avoid damage of SRM by thermal effects.
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Title: THE RELATIONSHIP BETWEEN SLUGGISH COGNITIVE TEMPO AND PERFORMANCE ON TASKS OF PROCESSING SPEED: INFLUENCE OF DEPRESSION
Creator: Kim, Jeong Hye
Date: 2021
Description: Sluggish cognitive tempo (SCT) is often associated with reported difficulties in various functional areas, including daily activities,...
Show moreSluggish cognitive tempo (SCT) is often associated with reported difficulties in various functional areas, including daily activities, emotional functioning, cognitive functioning, academic performance, and sleep. However, there are only a handful of research studies on SCT and neurocognitive functioning in adult populations, and the neuropsychological profile of SCT in adults is unclear.The purpose of this research is to investigate the effect of depression on the relationship between a self-reported measure of SCT and objective measures of SCT in adults by focusing on processing speed performance. The result of this research supports the previous notion that SCT is a novel and independent condition distinct from ADHD, and there are significantly positive relationships between symptoms of SCT and Inattention and Hyperactivity/Impulsivity. Furthermore, SCT and depression are also positively associated indicating the people who experience more symptoms of SCT report more symptoms of depression. However, results did not support the hypothesis that SCT significantly contribute to differences in performance on various types of neuropsychological tasks (WAIS PSI, Trail Making Test, and CPT-II Reaction Time) assessing processing speed after controlling for symptoms of ADHD (inattention and hyperactivity/impulsivity) and symptoms of depression. It is notable that the significant model beta weights for SCT in the final regression model suggests that the relationship between SCT and processing speed is worthy of additional investigation.
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Title: MULTICRITERIA DECISION-MAKING METHODOLOGY WITH TRADEOFF ANALYSIS FOR TRANSPORTATION BUDGET ALLOCATION
Creator: Truong, Tung Quoc
Date: 2022
Description: Transportation agencies in the United States nowadays rely on tax dollars for maintaining surface transportation infrastructure, which mainly...
Show moreTransportation agencies in the United States nowadays rely on tax dollars for maintaining surface transportation infrastructure, which mainly comes from fuel tax. However, travel behaviors are changing every day. People and businesses demand better and safer roads. Yet, consumers travel in more fuel-efficient vehicles and buy less gas, which means less revenue for fixing aging roads and highways. Meanwhile, new construction and repair costs increase for our overburdened transportation systems. Transportation agencies, therefore, must use their limited funding more wisely to optimize the service performance and minimize risks (Li, 2018). The budget allocation problem in transportation is not an easy task. The consequences of an ineffective decision in allocating resources are multi-facet both in the short- and long-term, including degrading in the condition of transportation facilities, losing public trust, and increasing backlogs in maintenance and repair. Therefore, transportation agencies are seeking more robust and comprehensive data-driven strategies that take into account of agency’s strategic goals and regulatory requirements, user expectations, nature of the asset, availability of resources, and lifecycle cost analysis in determining the optimal allocation of resources and making the best use of available funds (Li and Sinha, 2004; Sinha and Labi, 2007). The proposed research aims to utilize the concept of multicriteria decision making coupled with a holistic asset management framework to support performance-based allocations of transportation budgets and help transportation agencies achieve the future vision of the nation’s strategic planning requirements to enable sustainable management of the system. A computational study for the real-world dataset obtained by a state Department of Transportation (DOT) is conducted using the proposed budget allocation method. The results from the computational study reveal that the proposed method can derive optimal decision solutions for transportation budget allocation problems and can be utilized by transportation agencies on different scales – urban and rural, in other sectors – public and private, to effectively manage the transportation infrastructure sustainably, by effectively spending transportation budget to maximize service performance and minimize operating costs.
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