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- All Subjects: Materials Science
- All Subjects: Educational leadership
- Genre: Academic theses
- Creators: Arizona State University
- Status: Published
Description
The purpose of this action research study was to better understand how aspiring school leaders orient themselves toward present and future uncertainty and to explore what mindsets and conceptual understandings they believe they need to lead through uncertainty. An innovation, delivered through a graduate course on leading change in a Master of Educational Leadership program, focused on supporting participants’ mindsets and conceptual understanding toward leading change in the midst of uncertainty, including the COVID-19 global pandemic. A total of 34 students participated in this qualitative case study. The educational innovation was designed by this action researcher and was informed by transformative leadership theory, design thinking, and imagination. Four sources of data were used to answer the research questions, including students’ written assignments and video reflection assignments, as well as researcher course observations and semi-structured interviews with participants. Major findings suggested that the educational innovation was effective in supporting participants identity development as transformative leaders, as well as supporting participants’ adoption of design thinking mindsets and use of imagination as tools for leading change in complex systems and during uncertain times.
ContributorsScragg, Benjamin S (Author) / Giorgis, Cyndi (Thesis advisor) / Hermanns, Carl (Committee member) / Loescher, Shawn T (Committee member) / Arizona State University (Publisher)
Created2021
Description
There is a high demand for customized designs of various types of cement-based materials in order to address specific purposes in the construction field. These demands stem from the need to optimize the cementitious matrix properties and reinforcement choices, especially in high reliability, durability, and performance applications that include infrastructure, energy production, commercial buildings, and may ultimately be extended to low risk/high volume applications such as residential applications. The typical tools required to guide practicing engineers should be based on optimization algorithms that require highly efficient capacity and design alternatives and optimal computational tools. The general case of flexural design of members is an important aspect of design of structural members which can be extended to a variety of applications that include various cross-sections such as rectangular, W-sections, channels, angles, and T sections. The model utilized the simplified linear constitutive response of cement-based composite in compression and tension and extends into a two-segment elastic-plastic, strain softening, hardening, tension-stiffening, and a multi-segment system. The generalized parametric model proposed uses a dimensionless system in the stress-strain materials diagram to formulate piecewise equations for an equilibrium of internal stresses and obtains strain distributions for the closed-form solution of neutral axis location. This would allow for the computation of piecewise moment-curvature response. The number of linear residual stress implemented is flexible to a user to maintain a robust response. In the present approach bilinear, trilinear, and quad-linear models are addressed and a procedure for incorporating additional segments is presented. Moreover, a closed-form solution of moment-curvature can be solved and employed in calculating load-deflection response. The model is adaptable for various types of fiber-reinforced and textile reinforced concrete (FRC, TRC, UHPC, AAC, and Reinforced Concrete). The extensions to cover continuous fiber reinforcement such as textile reinforced concrete (TRC, FRCM) strengthening and repair are addressed. The theoretical model is extended to incorporate the hybrid design (HRC) with continuous rebar with FRC to increase the ductility and ultimate moment capacity. HRC extends the performance of the fiber system to incorporate residual capacity into a serviceability-based design that reduced the reliance on the design based on the limit state. The design chart for HRC and as well as conventional RC has been generated for practicing engineering applications. Results are compared to a large array of data from experimental results conducted at the ASU structural lab facilities and other published literature.
Contributorspleesudjai, chidchanok (Author) / Mobasher, Barzin (Thesis advisor) / Neithalath, Narayanan (Committee member) / Rajan, Subramaniam (Committee member) / Arizona State University (Publisher)
Created2021
Description
Federal, state, and local entities prioritized addressing these academic deficiencies over the past several decades. An area of concern for teachers and families is multiplication. The two main purposes of this study are to (1) to determine how multiplication achievement and strategy use change from beginning to end of Bilingual Family Math Club, and (2) determine which of the eight components of Bilingual Family Math Club (BFMC) contribute to student learning outcomes. The components of BFMC are (1) Concrete Representational Abstract (CRA) modeling, (2) explicit vocabulary instruction, (3) word problems, (4) homework, (5) math games, (6) adult/child pairs as family engagement, (7) bilingual instruction, and (8) workshop series. Quantitative data includes pre-and post-intervention student math assessments. Qualitative data includes analysis of the scratch work artifacts students produced solving those assessments, as well as post-intervention from adults and students enrolled in the club. Findings from this study support previous research. Families said six of the components of the club helped them the most: adult-child pairs, series workshops, games during class, the CRA method, homework as games, and having a bilingual club. Two of the eight BFMC components families felt did not support them in learning multiplication were word problems and explicit vocabulary instruction. Quantitative results from a paired sample t-test showed a statistically significant change and large effect sizes in post-assessment scores in all four areas of the assessment: fluency, word problems, single-digit facts, and multi-digit multiplication. This study provided critical information for school leaders and district personnel attempting to implement more effective after school support programs for families in mathematics.
ContributorsSchroeder, Brittany (Author) / Basile, Carole (Thesis advisor) / Bernstein, Katherine (Committee member) / Ross, Lydia (Committee member) / Arizona State University (Publisher)
Created2021
Description
Though National Board Certified Teachers (NBCTs) in Arizona have been identified as leaders on a national level, they do not have comparable opportunities to lead within their local contexts or engage in leadership and collaboration activities that align with Interstate Teacher Assessment and Support Consortium (InTASC) Standard 10. The purpose of this sequential, mixed-methods study was to explore how the development of a teacher leadership community of practice for NBCTs might influence their perceptions of themselves as leaders. Social constructionism, action research, and communities of practice guided the innovation and a mixed-methods approach was used for data collection and analysis. Data illustrated NBCTs’ dichotomous feelings about leadership on local and national levels. Findings revealed that NBCTs need continued professional learning opportunities, beyond National Board Certification, to resolve feelings of isolation and fully meet all of the leadership and collaboration indicators for InTASC Standard 10. Participating in a teacher leadership community of practice (a) provided a professional learning opportunity for NBCTs, (b) improved NBCTs’ perceptions of teacher leadership and helped them define it as an active process of learning, reflection, and action, and (c) increased NBCTs’ readiness to take action as teacher leaders within their local contexts to evoke positive change.
ContributorsAdams, Alaina (Author) / Marley, Scott C. (Thesis advisor) / Koro-Ljungberg, Mirka (Committee member) / Allen, Althe (Committee member) / Arizona State University (Publisher)
Created2016
Description
Many medical students are reluctant to seek help during the course of their four years of medical school. When they do finally ask for help, some are already burned out or in a crisis. One of the main reasons students are apprehensive about seeking help is stigma. This mixed methods action research study was conducted to explore whether a help-seeking, anti-stigma campaign improved help-seeking behaviors. The innovation was an anti-stigma campaign consisting of three components: (a) video vignettes of upper class students normalizing help-seeking, (b) a Friends and Family of Medical Students session to educate those closest to the student about medical school, and (c) an anonymous, online mental health screening tool. Data from the General Help-Seeking Questionnaire, individual interviews, and institutional data from the medical school provided information about the effects of the campaign and determined factors influencing help-seeking. Using these strategies, I hoped to normalize help-seeking and break down the barriers of stigma. Major findings included: Students were more likely to seek help from personal resources (close family and friends); Students may be more proactive with personal resources, but need prompting for college or formal resources; Students’ beliefs and attitudes were influenced by those closest to them and; First year students were more likely to seek help than their second year classmates. In addition, data inspired future research ideas and programming regarding the topic of help-seeking in medical school.
ContributorsSmith, Stephanie (Author) / Marley, Scott C. (Thesis advisor) / Buss, Ray R. (Committee member) / McEchron, Matthew D. (Committee member) / Arizona State University (Publisher)
Created2016
Description
Multifunctional oxide thin-films grown on silicon and several oxide substrates have been characterized using High Resolution (Scanning) Transmission Electron Microscopy (HRTEM), Energy-Dispersive X-ray Spectroscopy (EDX), and Electron Energy-Loss Spectroscopy (EELS). Oxide thin films grown on SrTiO3/Si pseudo-substrate showed the presence of amorphised SrTiO3 (STO) at the STO/Si interface. Oxide/oxide interfaces were observed to be atomically clean with very few defects.
Al-doped SrTiO3 thin films grown on Si were of high crystalline quality. The Ti/O ratio estimated from EELS line scans revealed that substitution of Ti by Al created associated O vacancies. The strength of the crystal field in STO was measured using EELS, and decreased by ~1.0 eV as Ti4+ was substituted by Al3+. The damping of O-K EELS peaks confirmed the rise in oxygen vacancies. For Co-substituted STO films grown on Si, the EDS and EELS spectra across samples showed Co doping was quite random. The substitution of Ti4+ with Co3+ or Co2+ created associated oxygen vacancies for charge balance. Presence of oxygen vacancies was also confirmed by shift of Ti-L EELS peaks towards lower energy by ~0.4 eV. The crystal-field strength decreased by ~0.6 eV as Ti4+ was partially substituted by Co3+ or Co2+.
Spinel Co3O4 thin films grown on MgAl2O4 (110) were observed to have excellent crystalline quality. The structure of the Co3O4/MgAl2O4 interface was determined using HRTEM and image simulations. It was found that MgAl2O4 substrate is terminated with Al and oxygen. Stacking faults and associated strain fields in spinel Co3O4 were found along [111], [001], and [113] using Geometrical Phase Analysis.
NbO2 films on STO (111) were observed to be tetragonal with lattice parameter of 13.8 Å and NbO films on LSAT (111) were observed to be cubic with lattice parameter of 4.26 Å. HRTEM showed formation of high quality NbOx films and excellent coherent interface. HRTEM of SrAl4 on LAO (001) confirmed an island growth mode. The SrAl4 islands were highly crystalline with excellent epitaxial registry with LAO. By comparing HRTEM images with image simulations, the interface structure was determined to consist of Sr-terminated SrAl4 (001) on AlO2-terminated LAO (001).
Al-doped SrTiO3 thin films grown on Si were of high crystalline quality. The Ti/O ratio estimated from EELS line scans revealed that substitution of Ti by Al created associated O vacancies. The strength of the crystal field in STO was measured using EELS, and decreased by ~1.0 eV as Ti4+ was substituted by Al3+. The damping of O-K EELS peaks confirmed the rise in oxygen vacancies. For Co-substituted STO films grown on Si, the EDS and EELS spectra across samples showed Co doping was quite random. The substitution of Ti4+ with Co3+ or Co2+ created associated oxygen vacancies for charge balance. Presence of oxygen vacancies was also confirmed by shift of Ti-L EELS peaks towards lower energy by ~0.4 eV. The crystal-field strength decreased by ~0.6 eV as Ti4+ was partially substituted by Co3+ or Co2+.
Spinel Co3O4 thin films grown on MgAl2O4 (110) were observed to have excellent crystalline quality. The structure of the Co3O4/MgAl2O4 interface was determined using HRTEM and image simulations. It was found that MgAl2O4 substrate is terminated with Al and oxygen. Stacking faults and associated strain fields in spinel Co3O4 were found along [111], [001], and [113] using Geometrical Phase Analysis.
NbO2 films on STO (111) were observed to be tetragonal with lattice parameter of 13.8 Å and NbO films on LSAT (111) were observed to be cubic with lattice parameter of 4.26 Å. HRTEM showed formation of high quality NbOx films and excellent coherent interface. HRTEM of SrAl4 on LAO (001) confirmed an island growth mode. The SrAl4 islands were highly crystalline with excellent epitaxial registry with LAO. By comparing HRTEM images with image simulations, the interface structure was determined to consist of Sr-terminated SrAl4 (001) on AlO2-terminated LAO (001).
ContributorsDhamdhere, Ajit (Author) / Smith, David J. (Thesis advisor) / McCartney, Martha R. (Committee member) / Chamberlin, Ralph (Committee member) / Ponce, Fernando (Committee member) / Arizona State University (Publisher)
Created2015
Description
Biogenic silica nanostructures, derived from diatoms, possess highly ordered porous hierarchical nanostructures and afford flexibility in design in large part due to the availability of a great variety of shapes, sizes, and symmetries. These advantages have been exploited for study of transport phenomena of ions and molecules towards the goal of developing ultrasensitive and selective filters and biosensors. Diatom frustules give researchers many inspiration and ideas for the design and production of novel nanostructured materials. In this doctoral research will focus on the following three aspects of biogenic silica: 1) Using diatom frustule as protein sensor. 2) Using diatom nanostructures as template to fabricate nano metal materials. 3) Using diatom nanostructures to fabricate hybrid platform.
Nanoscale confinement biogenetic silica template-based electrical biosensor assay offers the user the ability to detect and quantify the biomolecules. Diatoms have been demonstrated as part of a sensor. The sensor works on the principle of electrochemical impedance spectroscopy. When specific protein biomarkers from a test sample bind to corresponding antibodies conjugated to the surface of the gold surface at the base of each nanowell, a perturbation of electrical double layer occurs resulting in a change in the impedance.
Diatoms are also a new source of inspiration for the design and fabrication of nanostructured materials. Template-directed deposition within cylindrical nanopores of a porous membrane represents an attractive and reproducible approach for preparing metal nanopatterns or nanorods of a variety of aspect ratios. The nanopatterns fabricated from diatom have the potential of the metal-enhanced fluorescence to detect dye-conjugated molecules.
Another approach presents a platform integrating biogenic silica nanostructures with micromachined silicon substrates in a micro
ano hybrid device. In this study, one can take advantages of the unique properties of a marine diatom that exhibits nanopores on the order of 40 nm in diameter and a hierarchical structure. This device can be used to several applications, such as nano particles separation and detection. This platform is also a good substrate to study cell growth that one can observe the reaction of cell growing on the nanostructure of frustule.
Nanoscale confinement biogenetic silica template-based electrical biosensor assay offers the user the ability to detect and quantify the biomolecules. Diatoms have been demonstrated as part of a sensor. The sensor works on the principle of electrochemical impedance spectroscopy. When specific protein biomarkers from a test sample bind to corresponding antibodies conjugated to the surface of the gold surface at the base of each nanowell, a perturbation of electrical double layer occurs resulting in a change in the impedance.
Diatoms are also a new source of inspiration for the design and fabrication of nanostructured materials. Template-directed deposition within cylindrical nanopores of a porous membrane represents an attractive and reproducible approach for preparing metal nanopatterns or nanorods of a variety of aspect ratios. The nanopatterns fabricated from diatom have the potential of the metal-enhanced fluorescence to detect dye-conjugated molecules.
Another approach presents a platform integrating biogenic silica nanostructures with micromachined silicon substrates in a micro
ano hybrid device. In this study, one can take advantages of the unique properties of a marine diatom that exhibits nanopores on the order of 40 nm in diameter and a hierarchical structure. This device can be used to several applications, such as nano particles separation and detection. This platform is also a good substrate to study cell growth that one can observe the reaction of cell growing on the nanostructure of frustule.
ContributorsLin, Kai-Chun (Author) / Ramakrishna, B.L. (Thesis advisor) / Goryll, Michael (Thesis advisor) / Dey, Sandwip (Committee member) / Prasad, Shalini (Committee member) / Arizona State University (Publisher)
Created2014
Description
ABSTRACT
The purpose of this descriptive study was to gain an understanding of the confidence level held by third, fourth, and fifth grade teachers as to their preparedness for teaching the cognitive demands of the Common Core State Standards (Arizona's College and Career Ready Standards) to all students, in particular Hispanic students living in poverty, who occupy close to a third of all classroom seats in Arizona. The achievement gap between Hispanic students living in poverty and non-Hispanic students of non-poverty status is one of the largest achievement gaps in Arizona, which has existed with minimal change for more than 12 years. By gaining an understanding of the teachers' confidence in teaching critical thinking skills, further support and professional development is suggested to link a teacher's knowledge to instructional practice that in turn increases the academic achievement of Arizona's poor Hispanic students.
The process of gaining this understanding was by using a multi-dimensional survey with 500 third through fifth grade teachers in two uniquely different, but representative, Arizona school districts. Approximately one-third of those teachers responded to the multi-dimensional survey about teaching the critical thinking (CT) skills of Arizona's College and Career Ready Standards for English Language Arts. The survey asked teachers to rate their levels of preparedness for teaching CT to several types of students, to choose a CT definition, describe the relationship of CT and reading, explain how they teach CT to students who are reading below grade level, express the support they need to teach CT to those students, and rate the effectiveness of several CT classroom vignettes for different types of students. Although the questions involved several types of students, the primary focus was on exploring the teachers' position with teaching CT to Low SES Hispanic students.
A disconnect was revealed between the teachers' perception that they had the ability and knowledge necessary to teach critical thinking skills and their ability to identify ineffective critical thinking instructional practices. This disconnect may be interfering with the link between the professional development teachers are currently receiving to implement Common Core State Standards and teachers actively engaging in learning what is needed to effectively teach critical thinking skills to their students.
The purpose of this descriptive study was to gain an understanding of the confidence level held by third, fourth, and fifth grade teachers as to their preparedness for teaching the cognitive demands of the Common Core State Standards (Arizona's College and Career Ready Standards) to all students, in particular Hispanic students living in poverty, who occupy close to a third of all classroom seats in Arizona. The achievement gap between Hispanic students living in poverty and non-Hispanic students of non-poverty status is one of the largest achievement gaps in Arizona, which has existed with minimal change for more than 12 years. By gaining an understanding of the teachers' confidence in teaching critical thinking skills, further support and professional development is suggested to link a teacher's knowledge to instructional practice that in turn increases the academic achievement of Arizona's poor Hispanic students.
The process of gaining this understanding was by using a multi-dimensional survey with 500 third through fifth grade teachers in two uniquely different, but representative, Arizona school districts. Approximately one-third of those teachers responded to the multi-dimensional survey about teaching the critical thinking (CT) skills of Arizona's College and Career Ready Standards for English Language Arts. The survey asked teachers to rate their levels of preparedness for teaching CT to several types of students, to choose a CT definition, describe the relationship of CT and reading, explain how they teach CT to students who are reading below grade level, express the support they need to teach CT to those students, and rate the effectiveness of several CT classroom vignettes for different types of students. Although the questions involved several types of students, the primary focus was on exploring the teachers' position with teaching CT to Low SES Hispanic students.
A disconnect was revealed between the teachers' perception that they had the ability and knowledge necessary to teach critical thinking skills and their ability to identify ineffective critical thinking instructional practices. This disconnect may be interfering with the link between the professional development teachers are currently receiving to implement Common Core State Standards and teachers actively engaging in learning what is needed to effectively teach critical thinking skills to their students.
ContributorsFast, Deborah (Author) / Fischman, Gustavo E (Thesis advisor) / Harris, Connie (Committee member) / Bader, Beth (Committee member) / Arizona State University (Publisher)
Created2014
Description
The work described in this thesis explores the synthesis of new semiconductors in the Si-Ge-Sn system for application in Si-photonics. Direct gap Ge1-ySny (y=0.12-0.16) alloys with enhanced light emission and absorption are pursued. Monocrystalline layers are grown on Si platforms via epitaxy-driven reactions between Sn- and Ge-hydrides using compositionally graded buffer layers that mitigate lattice mismatch between the epilayer and Si platforms. Prototype p-i-n structures are fabricated and are found to exhibit direct gap electroluminescence and tunable absorption edges between 2200 and 2700 nm indicating applications in LEDs and detectors. Additionally, a low pressure technique is described producing pseudomorphic Ge1-ySny alloys in the compositional range y=0.06-0.17. Synthesis of these materials is achieved at ultra-low temperatures resulting in nearly defect-free films that far exceed the critical thicknesses predicted by thermodynamic considerations, and provide a chemically driven route toward materials with properties typically associated with molecular beam epitaxy.
Silicon incorporation into Ge1-ySny yields a new class of Ge1-x-ySixSny (y>x) ternary alloys using reactions between Ge3H8, Si4H10, and SnD4. These materials contain small amounts of Si (x=0.05-0.08) and Sn contents of y=0.1-0.15. Photoluminescence studies indicate an intensity enhancement relative to materials with lower Sn contents (y=0.05-0.09). These materials may serve as thermally robust alternatives to Ge1-ySny for mid-infrared (IR) optoelectronic applications.
An extension of the above work is the discovery of a new class of Ge-like Group III-V-IV hybrids with compositions Ga(As1–xPx)Ge3 (x=0.01-0.90) and (GaP)yGe5–2y related to Ge1-x-ySixSny in structure and properties. These materials are prepared by chemical vapor deposition of reactive Ga-hydrides with P(GeH3)3 and As(GeH3)3 custom precursors as the sources of P, As, and Ge incorporating isolated GaAs and GaP donor-acceptor pairs into diamond-like Ge-based structures. Photoluminescence studies reveal bandgaps in the near-IR and large bowing of the optical behavior relative to linear interpolation of the III-V and Ge end members. Similar materials in the Al-Sb-B-P system are also prepared and characterized. The common theme of the above topics is the design and fabrication of new optoelectronic materials that can be fully compatible with Si-based technologies for expanding the optoelectronic capabilities of Ge into the mid-IR and beyond through compositional tuning of the diamond lattice.
Silicon incorporation into Ge1-ySny yields a new class of Ge1-x-ySixSny (y>x) ternary alloys using reactions between Ge3H8, Si4H10, and SnD4. These materials contain small amounts of Si (x=0.05-0.08) and Sn contents of y=0.1-0.15. Photoluminescence studies indicate an intensity enhancement relative to materials with lower Sn contents (y=0.05-0.09). These materials may serve as thermally robust alternatives to Ge1-ySny for mid-infrared (IR) optoelectronic applications.
An extension of the above work is the discovery of a new class of Ge-like Group III-V-IV hybrids with compositions Ga(As1–xPx)Ge3 (x=0.01-0.90) and (GaP)yGe5–2y related to Ge1-x-ySixSny in structure and properties. These materials are prepared by chemical vapor deposition of reactive Ga-hydrides with P(GeH3)3 and As(GeH3)3 custom precursors as the sources of P, As, and Ge incorporating isolated GaAs and GaP donor-acceptor pairs into diamond-like Ge-based structures. Photoluminescence studies reveal bandgaps in the near-IR and large bowing of the optical behavior relative to linear interpolation of the III-V and Ge end members. Similar materials in the Al-Sb-B-P system are also prepared and characterized. The common theme of the above topics is the design and fabrication of new optoelectronic materials that can be fully compatible with Si-based technologies for expanding the optoelectronic capabilities of Ge into the mid-IR and beyond through compositional tuning of the diamond lattice.
ContributorsWallace, Patrick Michael (Author) / Kouvetakis, John (Thesis advisor) / Menéndez, Jose (Committee member) / Trovitch, Ryan (Committee member) / Arizona State University (Publisher)
Created2018
Description
In this dissertation, micro-galvanic corrosion effects and passivation behavior of single-phase binary alloys have been studied in order to formulate new insights towards the development of “stainless-like” lightweight alloys. As a lightweight material of interest, Mg-xAl alloys were studied using aqueous free corrosion, atmospheric corrosion, dissolution rate kinetics, and ionic liquid dissolution. Polarization and “accelerated” free corrosion studies in aqueous chloride were used to characterize the corrosion behavior and morphology of alloys. Atmospheric corrosion experiments revealed surface roughness and pH evolution behavior in aqueous environment. Dissolution in absence of water using choline-chloride:urea ionic liquid allowed for a simpler dissolution mechanism to be observed, providing additional insights regarding surface mobility of Al. These results were compared with commercial alloy (AZ31B, AM60, and AZ91D) behavior to better elucidate effects associated with secondary phases and intermetallic particles often present in Mg alloys. Aqueous free corrosion, “accelerated” free corrosion and ionic liquid dissolution studies have confirmed Al surface enrichment in a variety of morphologies, including Al-rich platelet and Al nanowire formation. This behavior is attributed to the preferential dissolution of Al as the more “noble” element in the matrix. Inductively-coupled mass spectroscopy was used to measure first-order rate reaction constants for elemental Mg and Al dissolution in aqueous chloride environment to be kMg= 9.419 x 10-6 and kAl = 2.103 x 10-6 for future implementation in kinetic Monte Carlo simulations. To better understand how “stainless-like” passivation may be achieved, Ni-xCr alloys were studied using polarization and potential pulse experiments. The passivation potential, critical current density, and passivation current density were found to decay with increasing Cr composition. The measured average number of monolayers dissolved during passivation was found to be in good agreement with percolation theory, with a fitted 3-D percolation threshold of p_c^3D=0.118 compared with the theoretical value of 0.137. Using these results, possible approaches towards achieving passivation in other systems, including Mg-Al, are discussed.
ContributorsAiello, Ashlee (Author) / Sieradzki, Karl (Thesis advisor) / Buttry, Daniel (Committee member) / Chan, Candace (Committee member) / Crozier, Peter (Committee member) / Arizona State University (Publisher)
Created2018