June 2019 - Msepostdoc-list

Seminar Reminder for Keyou Mao's Ph.D. Final Exam. Seminar Thursday, June 13, at 2:00 p.m., in ARMS 1028. Exam same day, at 3:00, in ARMS 2237. " Influence of Irradiation and Laser Welding on Deformation Mechanisms in Austenitic Steels
by Son, Rosemary E 12 Jun '19

12 Jun '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Influence of Irradiation and Laser Welding on Deformation Mechanisms in Austenitic Steels" By Keyou Mao Purdue MSE Ph.D. Final Exam Advisors: Professor Janelle P. Wharry and Professor Xinghang Zhang ABSTRACT This presentation will describe recent advancements in micro-mechanical testing that inform how deformation mechanisms in 304L stainless steels (SS) are affected by the presence of irradiation-induced defects. Austenitic 304L SS is one of the most widely utilized structural alloys in nuclear energy systems, but the role of irradiation on its underlying mechanisms of mechanical deformation remains relatively poorly understood. Now, recent advancement of micro-scale mechanical testing in a scanning electron microscope (SEM), coupled with site-specific transmission electron microscopy (TEM), enables us to precisely determine deformation mechanisms as a function of plastic strain and grain orientation. We focus on AISI 304L stainless steel irradiated in EBR-II to 20 displacements per atom (dpa) at 415°C, and contains ~3 atomic parts per million (appm) He amounting to 1.5% swelling. A portion of the specimen is laser welded in-hot cell; the laser weld heat affected zone (HAZ) is studied and considered to have undergone post-irradiation annealing (PIA). An archival, virgin specimen is also studied as a control. We conduct nanoindentation then prepare TEM lamellae from the indent plastic zone. TEM investigation reveals nucleation of deformation-induced α' martensite in the irradiated specimen, and metastable ε martensite in the PIA specimen. Meanwhile, the unirradiated control specimen exhibits evidence only of dislocation slip and twinning; this is unsurprising given that alternative deformation mechanisms such as twinning and martensitic transformation are typically observed only near cryogenic temperatures in austenitic SS. Surface area of irradiation-produced cavities contribute sufficient free energy to accommodate the martensitic transformation. The lower population of cavities in the PIA material enables ε martensite formation, while the higher cavity number density in the irradiated material causes α' martensite fromation. SEM-based micropillar compression tests confirm nanoindentation results. Irradiation damage could enable fundamental, mechanistic studies of deformation mechanisms that are typically only accessible at extremely low temperatures. Date: Thursday, June 13, 2019 Time: 2:00 P.M. Place: ARMS 1028

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Seminar Reminder for Li-Kai Lin's Ph.D. Final Exam. Seminar Thursday, June 13, at 10:00 a.m., in ARMS 1028. Exam, same day, at 11:00 a.m., in ARMS 2237. " Pollutant and Inflammation Marker Detection using Low-Cost and Portable Microfluidic Platform, an
by Son, Rosemary E 12 Jun '19

12 Jun '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Pollutant and Inflammation Marker Detection using Low-Cost and Portable Microfluidic Platform, and Flexible Microelectronic Platform" By Li-Kai Lin Purdue MSE Ph.D. Final Exam Advisor: Professor Lia Stanciu ABSTRACT Existing methods for pathogen/pollutant detection or wound infection monitoring employ high-cost instruments that could only be operated by trained personnel, and costly device-based detection requires a time-consuming field-to-lab process. This expensive process with multiple prerequisites prolongs the time that patients must wait for a diagnosis. Therefore, improved methods for point-of-care biosensing are necessary. In this study, we aimed to develop a direct, easy-to-use, portable, low cost, highly sensitive and selective sensor platform with the goal of pollutant detection and wound infection/cancer migration monitoring. This study has two main parts, including microfluidic, electrical, and optical sensing platforms. The first part focuses on Bisphenol A (BPA) lateral flow assay (LFA) detection; the second part focuses on the electrical sensing platform fabrication for one of the markers of inflammation, matrix metalloproteinases-9 (MMP-9), monitoring/detection. In the first part, we found that the few lateral flow assays (LFAs) established for detecting the endocrine-disrupting chemical BPA have employed citrate-stabilized gold nanoparticles (GNPs), which have inevitable limitations and instability issues. To address these limitations, a more stable and more sensitive biosensor is developed by designing strategies for modifying the surfaces of GNPs with polyethylene glycol and then testing their effectiveness and sensitivity toward BPA in an LFA. In addition, we describe the development of a new range-extended bisphenol A (BPA) detection method that uses a surface enhanced Raman scattering lateral flow assay (SERS-LFA) binary system. Furthermore, we examine advanced bisphenol A (BPA) lateral flow assays (LFAs) that use multiple nanosystems. The assays include three nanosystems, namely, gold nanostars, gold nanocubes, and gold nanorods, which are rarely applied in LFAs, compared with general gold nanoparticles. The developed LFAs show different performances in the detection of BPA. In the second part, a stable electrical sensing platform is developed for MMP-9 detection. Date: Thursday, June 13, 2019 Time: 10:00 A.M. Place: ARMS 1028

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Seminar Reminder for Cuncai Fan's Ph.D. Final Exam. Seminar June 12, at 9:00 a.m., in ARMS 1028. Exam June 12, at 10:00, in ARMS 2237. " Radiation Response of Nanostructured Cu"
by Son, Rosemary E 11 Jun '19

11 Jun '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Radiation Response of Nanostructured Cu" By Cuncai Fan Purdue MSE Ph.D. Final Exam Advisor: Professor Xinghang Zhang ABSTRACT Irradiation of metals with energetic particles causes severe microstructural damage and degradation of mechanical properties. Prior studies on conventional polycrystalline materials have shown that the radiation tolerance of a material can often be enhanced by introducing a high density of interfaces that act as defect 'sinks' by attracting, absorbing and annihilating radiation induced defects. Nanostructured materials with a large volume fraction of interfaces, therefore, are assumed to be more radiation tolerant than conventional materials. This thesis focuses on understanding the fundamental mechanisms of radiation damage of nanostructured Cu fabricated by magnetron sputtering technique. High-density twin boundaries (TBs) and nanovoids (NVs) were successfully introduced into two distinct nanostructured Cu films with different orientations, including nanovoid-nanotwinned (NV-NT) Cu (111) and nanovoid (NV) Cu (110). The in-situ high-energy Kr ++ (1 MeV) and ex-situ low-energy (< 200 keV) He+ irradiations were subsequently preformed on the nanostructured Cu films. The in-situ TEM studies suggested that TBs and NVs are effective defect sinks that interact with defect clusters and impact their formation and distribution. Meanwhile, the preexisting nanostructures also undergo structural evolution under irradiation, in the form of void shrinkage and spheroidization, and twin boundary migration. In addition, the ex-situ micro-pillar compression tests revealed that the He-irradiated NV-NT Cu contains less defect clusters and maintain good work hardening ability. The underlying mechanisms of radiation-induced void shrinkage, twin boundary migration, and strengthening mechanisms are interpreted based on a combination of TEM analyses and molecular dynamics simulation, and phase-field modeling. This project provides important insight on the design of radiation tolerant nanostructured metals. Date: Wednesday, June 12, 2019 Time: 9:00 A.M. Place: ARMS 1028

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Seminar Reminder for Xing Sun's Ph.D. Final Exam. Seminar, Tuesday, June 11, at 9:00 a.m., in ARMS 1028; Exam same day, at 10:00 a.m., in ARMS 2326."Controllable Three-Dimensional Strain, Microstructure, Functionalities in Self-Assembled Nanocompos
by Son, Rosemary E 10 Jun '19

10 Jun '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Controllable Three-Dimensional Strain, Microstructure, Functionalities in Self-Assembled Nanocomposite Thin Films" By Xing Sun Purdue MSE Ph.D. Final Exam Advisor: Professor Haiyan Wang ABSTRACT Vertically aligned nanocomposite (VAN) configuration has been recognized as the state-of-the-art architecture in the complex oxide epitaxial thin films, which are constructed by two immiscible phases simultaneously and vertically growing on a given substrate and forming various columnar microstructures, such as nanopillars embedded in matrix, nanomaze, and nanocheckboard. Due to its architectural features, VAN structure enables a powerful control on the multifunctionalities via vertical strain engineering, microstructural variations, and interfacial coupling. It provides flexibility in complex oxide designs with various functionalities (e.g., electrical, magnetic, optical, etc.), as well as a platform to explore the correlations between strain, microstructure, and properties of thin films. In this dissertation, integrated VAN systems with multilayer configuration have been constructed as a new three-dimensional (3D) framework, e.g., inserting 1-3 layers of CeO2 (or LSMO) interlayers into the La0.7Sr0.3MnO3 (LSMO)-CeO2 VAN system and forming 3D interconnected CeO2 (or LSMO) skeleton embedded in LSMO matrix. This new VAN 3D framework enables both lateral and vertical strain engineering simultaneously within the films and obtains highly enhanced magnetotransport properties, such as the record high magnetoresistance (MR) value of ~51-66%, compared with its VAN single layer counterpart. In order to demonstrate the flexibility of this design, other systems such as 3D ZnO framework embedded in LSMO matrix have been constructed to explore the thickness effects of the ZnO interlayers on the magnetotransport properties of the LSMO-ZnO system. The maximum MR value is obtained at the ZnO interlayer thickness of ~2 nm, which enables the optimal magnetoresistance tunneling effect. Meanwhile, the significance of the interlayer selection in the microstructure and magnetotransport properties in the LSMO-ZnO system has been investigated by varying the interlayer materials yttria-stabilized zirconia (YSZ), CeO2, SrTiO3, BaTiO3, and MgO. The formed 3D heterogeneous framework provides a new dimension to tailor the microstructure, strain and functionalities within the films. Moreover, a new strain engineering approach with engineered tilted interfaces has been demonstrated by multilayering different VAN layers with various two phase ratio and creating a hybrid nanodumbbell structure within the LSMO-CeO2 VAN thin films. The nanodumbbell structure accomplishes a more efficient strain engineering and exhibits highly enhanced magnetic and magnetoresistance properties, compared with its VAN single layer and interlayer counterparts. These examples presented in the thesis demonstrate the flexibility and potential of 3D strain engineering in complex VAN systems and a higher level of property control, coupled with unique microstructures and interfaces. Beyond perovskites, these 3D designs can be extended to other material systems for a broad range of applications, such as energy conversion and storage devices. Date: Tuesday, June 11, 2019 Time: 9:00 A.M. Place: ARMS 1028

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Seminar Reminder for Xing Sun's Ph.D. Final Exam. Seminar, Tuesday, June 11, at 9:00 a.m., in ARMS 1028; Exam same day, at 10:00 a.m., in ARMS 2326. " Controllable Three-Dimensional Strain, Microstructure, Functionalities in Self-Assembled Nanocomposit
by Son, Rosemary E 05 Jun '19

05 Jun '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Controllable Three-Dimensional Strain, Microstructure, Functionalities in Self-Assembled Nanocomposite Thin Films" By Xing Sun Purdue MSE Ph.D. Final Exam Advisor: Professor Haiyan Wang ABSTRACT Vertically aligned nanocomposite (VAN) configuration has been recognized as the state-of-the-art architecture in the complex oxide epitaxial thin films, which are constructed by two immiscible phases simultaneously and vertically growing on a given substrate and forming various columnar microstructures, such as nanopillars embedded in matrix, nanomaze, and nanocheckboard. Due to its architectural features, VAN structure enables a powerful control on the multifunctionalities via vertical strain engineering, microstructural variations, and interfacial coupling. It provides flexibility in complex oxide designs with various functionalities (e.g., electrical, magnetic, optical, etc.), as well as a platform to explore the correlations between strain, microstructure, and properties of thin films. In this dissertation, integrated VAN systems with multilayer configuration have been constructed as a new three-dimensional (3D) framework, e.g., inserting 1-3 layers of CeO2 (or LSMO) interlayers into the La0.7Sr0.3MnO3 (LSMO)-CeO2 VAN system and forming 3D interconnected CeO2 (or LSMO) skeleton embedded in LSMO matrix. This new VAN 3D framework enables both lateral and vertical strain engineering simultaneously within the films and obtains highly enhanced magnetotransport properties, such as the record high magnetoresistance (MR) value of ~51-66%, compared with its VAN single layer counterpart. In order to demonstrate the flexibility of this design, other systems such as 3D ZnO framework embedded in LSMO matrix have been constructed to explore the thickness effects of the ZnO interlayers on the magnetotransport properties of the LSMO-ZnO system. The maximum MR value is obtained at the ZnO interlayer thickness of ~2 nm, which enables the optimal magnetoresistance tunneling effect. Meanwhile, the significance of the interlayer selection in the microstructure and magnetotransport properties in the LSMO-ZnO system has been investigated by varying the interlayer materials yttria-stabilized zirconia (YSZ), CeO2, SrTiO3, BaTiO3, and MgO. The formed 3D heterogeneous framework provides a new dimension to tailor the microstructure, strain and functionalities within the films. Moreover, a new strain engineering approach with engineered tilted interfaces has been demonstrated by multilayering different VAN layers with various two phase ratio and creating a hybrid nanodumbbell structure within the LSMO-CeO2 VAN thin films. The nanodumbbell structure accomplishes a more efficient strain engineering and exhibits highly enhanced magnetic and magnetoresistance properties, compared with its VAN single layer and interlayer counterparts. These examples presented in the thesis demonstrate the flexibility and potential of 3D strain engineering in complex VAN systems and a higher level of property control, coupled with unique microstructures and interfaces. Beyond perovskites, these 3D designs can be extended to other material systems for a broad range of applications, such as energy conversion and storage devices. Date: Tuesday, June 11, 2019 Time: 9:00 A.M. Place: ARMS 1028

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Seminar Notice for Li-Kai Lin's Ph.D. Final Exam. Seminar Thursday, June 13, at 10:00 a.m., in ARMS 1028. Exam, same day, at 11:00 a.m., in ARMS 2237. " Pollutant and Inflammation Marker Detection using Low-Cost and Portable Microfluidic Platform, and Fl
by Son, Rosemary E 03 Jun '19

03 Jun '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Pollutant and Inflammation Marker Detection using Low-Cost and Portable Microfluidic Platform, and Flexible Microelectronic Platform" By Li-Kai Lin Purdue MSE Ph.D. Final Exam Advisor: Professor Lia Stanciu ABSTRACT Existing methods for pathogen/pollutant detection or wound infection monitoring employ high-cost instruments that could only be operated by trained personnel, and costly device-based detection requires a time-consuming field-to-lab process. This expensive process with multiple prerequisites prolongs the time that patients must wait for a diagnosis. Therefore, improved methods for point-of-care biosensing are necessary. In this study, we aimed to develop a direct, easy-to-use, portable, low cost, highly sensitive and selective sensor platform with the goal of pollutant detection and wound infection/cancer migration monitoring. This study has two main parts, including microfluidic, electrical, and optical sensing platforms. The first part focuses on Bisphenol A (BPA) lateral flow assay (LFA) detection; the second part focuses on the electrical sensing platform fabrication for one of the markers of inflammation, matrix metalloproteinases-9 (MMP-9), monitoring/detection. In the first part, we found that the few lateral flow assays (LFAs) established for detecting the endocrine-disrupting chemical BPA have employed citrate-stabilized gold nanoparticles (GNPs), which have inevitable limitations and instability issues. To address these limitations, a more stable and more sensitive biosensor is developed by designing strategies for modifying the surfaces of GNPs with polyethylene glycol and then testing their effectiveness and sensitivity toward BPA in an LFA. In addition, we describe the development of a new range-extended bisphenol A (BPA) detection method that uses a surface enhanced Raman scattering lateral flow assay (SERS-LFA) binary system. Furthermore, we examine advanced bisphenol A (BPA) lateral flow assays (LFAs) that use multiple nanosystems. The assays include three nanosystems, namely, gold nanostars, gold nanocubes, and gold nanorods, which are rarely applied in LFAs, compared with general gold nanoparticles. The developed LFAs show different performances in the detection of BPA. In the second part, a stable electrical sensing platform is developed for MMP-9 detection. Date: Thursday, June 13, 2019 Time: 10:00 A.M. Place: ARMS 1028

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Seminar Notice for Keyou Mao's Ph.D. Final Exam. Seminar Thursday, June 13, at 2:00 p.m., in ARMS 1028. Exam same day, at 3:00, in ARMS 2237. " Influence of Irradiation and Laser Welding on Deformation Mechanisms in Austenitic Steels
by Son, Rosemary E 03 Jun '19

03 Jun '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Influence of Irradiation and Laser Welding on Deformation Mechanisms in Austenitic Steels" By Keyou Mao Purdue MSE Ph.D. Final Exam Advisors: Professor Janelle P. Wharry and Professor Xinghang Zhang ABSTRACT This presentation will describe recent advancements in micro-mechanical testing that inform how deformation mechanisms in 304L stainless steels (SS) are affected by the presence of irradiation-induced defects. Austenitic 304L SS is one of the most widely utilized structural alloys in nuclear energy systems, but the role of irradiation on its underlying mechanisms of mechanical deformation remains relatively poorly understood. Now, recent advancement of micro-scale mechanical testing in a scanning electron microscope (SEM), coupled with site-specific transmission electron microscopy (TEM), enables us to precisely determine deformation mechanisms as a function of plastic strain and grain orientation. We focus on AISI 304L stainless steel irradiated in EBR-II to 20 displacements per atom (dpa) at 415°C, and contains ~3 atomic parts per million (appm) He amounting to 1.5% swelling. A portion of the specimen is laser welded in-hot cell; the laser weld heat affected zone (HAZ) is studied and considered to have undergone post-irradiation annealing (PIA). An archival, virgin specimen is also studied as a control. We conduct nanoindentation then prepare TEM lamellae from the indent plastic zone. TEM investigation reveals nucleation of deformation-induced α' martensite in the irradiated specimen, and metastable ε martensite in the PIA specimen. Meanwhile, the unirradiated control specimen exhibits evidence only of dislocation slip and twinning; this is unsurprising given that alternative deformation mechanisms such as twinning and martensitic transformation are typically observed only near cryogenic temperatures in austenitic SS. Surface area of irradiation-produced cavities contribute sufficient free energy to accommodate the martensitic transformation. The lower population of cavities in the PIA material enables ε martensite formation, while the higher cavity number density in the irradiated material causes α' martensite fromation. SEM-based micropillar compression tests confirm nanoindentation results. Irradiation damage could enable fundamental, mechanistic studies of deformation mechanisms that are typically only accessible at extremely low temperatures. Date: Thursday, June 13, 2019 Time: 2:00 P.M. Place: ARMS 1028

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Seminar Notice for Cuncai Fan's Ph.D. Final Exam. Seminar June 12, at 9:00 a.m., in ARMS 1028. Exam June 12, at 10:00, in ARMS 2237. " Radiation Response of Nanostructured Cu"
by Son, Rosemary E 03 Jun '19

03 Jun '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Radiation Response of Nanostructured Cu" By Cuncai Fan Purdue MSE Ph.D. Final Exam Advisor: Professor Xinghang Zhang ABSTRACT Irradiation of metals with energetic particles causes severe microstructural damage and degradation of mechanical properties. Prior studies on conventional polycrystalline materials have shown that the radiation tolerance of a material can often be enhanced by introducing a high density of interfaces that act as defect 'sinks' by attracting, absorbing and annihilating radiation induced defects. Nanostructured materials with a large volume fraction of interfaces, therefore, are assumed to be more radiation tolerant than conventional materials. This thesis focuses on understanding the fundamental mechanisms of radiation damage of nanostructured Cu fabricated by magnetron sputtering technique. High-density twin boundaries (TBs) and nanovoids (NVs) were successfully introduced into two distinct nanostructured Cu films with different orientations, including nanovoid-nanotwinned (NV-NT) Cu (111) and nanovoid (NV) Cu (110). The in-situ high-energy Kr ++ (1 MeV) and ex-situ low-energy (< 200 keV) He+ irradiations were subsequently preformed on the nanostructured Cu films. The in-situ TEM studies suggested that TBs and NVs are effective defect sinks that interact with defect clusters and impact their formation and distribution. Meanwhile, the preexisting nanostructures also undergo structural evolution under irradiation, in the form of void shrinkage and spheroidization, and twin boundary migration. In addition, the ex-situ micro-pillar compression tests revealed that the He-irradiated NV-NT Cu contains less defect clusters and maintain good work hardening ability. The underlying mechanisms of radiation-induced void shrinkage, twin boundary migration, and strengthening mechanisms are interpreted based on a combination of TEM analyses and molecular dynamics simulation, and phase-field modeling. This project provides important insight on the design of radiation tolerant nanostructured metals. Date: Wednesday, June 12, 2019 Time: 9:00 A.M. Place: ARMS 1028

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Seminar Reminder for Sabrina Huang's Ph.D. Final Exam Tuesday, June 4, at 9:00 a.m., in ARMS 1028. Exam same day at 10:00, in ARMS 2326 "Investigation of Biodegradable Iron-Manganese Alloys with Various Porosity"
by Son, Rosemary E 03 Jun '19

03 Jun '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Investigation of Biodegradable Iron-Manganese Alloys with Various Porosity" By Sabrina M. Huang Purdue MSE Ph.D. Final Exam Advisor: Professor Lia Stanciu ABSTRACT Bioresorbable iron-manganese (Fe-Mn) alloys are considered as a new class of biomaterials for the development of temporary orthopedic fixation devices due to their promising mechanical properties and the ability to degrade in the physiological environment. These materials release small quantities of metallic ions/particles that are absorbable by the host upon their biodegradation. The greatest challenge for developing an ideal resorbable Fe-Mn alloy is to increase the degradation rate of the alloy while maintaining biocompatibility, i.e. causing zero or minimal local and systemic toxicity to the tissue. Another challenge is to improve osteo-integration through inducing a cascade of events leading to tissue ingrowth. The focus of this presentation is on balancing all of these requirements by introducing porosity for increased biodegradation and collagen type I coatings for osteo-integration. The microstructure and mechanical properties of the alloys, as well as the influence of the degree of porosity on the corrosion rates in relation to the concentrations of released metal ions were investigated. We also present on the effect of Type I Collagen coating on cellular compatibility and corrosion rates. With the incorporation of porosity and surface coating with Type I collagen, Fe-30Mn alloys could become the next generation transient fracture fixation medical devices. Date: Tuesday, June 4, 2019 Time: 9:00 A.M. Place: ARMS 1028

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