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Title: Modelling The Structure & Chemistry Of GaAs Oxides During Surface Energy Engineering (See) For Nano-bonding
Faculty Advisor: Dr. Nicole Herbots
Abstract: Si absorbs electromagnetic waves between 400 and 1100 nm while GaAs absorbs between 800 and 2000 nm. When Si and GaAs are integrated into a hetero-structure, to create a monolithic photo-voltaic converter, a.k.a tandem Si-GaAs- solar cell, the bonded Si/GaAs pair can absorb a larger spectrum of wavelengths more efficiently, leading to potentially photovoltaic conversion efficiency 30-40%. Native oxide removal is key for optimizing the conversion efficiency of photoelectric devices, because they interfere with electrical carriers transport.
The present work focuses on removing native oxides in air on GaAs(100) prior to bonding Si(100). The two semiconductors surfaces undergo Surface Energy Engineering (SEE) to remove native oxides and create so-called â€œprecursor phasesâ€ *1, 2* planar at the nano-scale, to catalyze molecular cross-bonding between the two surfaces during contacting at the nano-scale (nano-contacting). To accomplish nano-contacting and nucleate two-dimensional complementary precursors phases on Si and GaAs, Si(100) and GaAs(100) undergo a chemical process design via SEE in a Class 10 chemical laminar flow hood in a Class 100 clean-room. The goal of SEE is removing native oxides, planarizing surfaces the nano-scale, by extending the width of atomic terraces from less than 2nm, to more than 20 nm, and nucleating complementary precursor phases, to create Si/GaAs heterostructures bonded at the molecular levels.
Title: Presolar Grain Isolation: A Novel Development Using Focused Ion Beam (FIB)
Faculty Advisor: Dr. Maitrayee Bose
Abstract: We present a new methodology of isolating presolar grains by performing FIB milling in Acfer 094 meteorite. We want to develop a technique to isolate presolar grains in meteorites using focused ion beam (FIB) milling for future nanoscale secondary ion mass spectrometry (NanoSIMS) measurements. The NanoSIMS instrument uses a primary ion beam to blast a given sample surface, extracts secondary ions, and separates these ions into their mass/charge ratio, allowing isotopic measurements. We plan to use the O- ion beam on the NanoSIMS for isotopic measurements, which can be as small as ~100 nm. Presolar silicate grains are in the size range between ~90-300 nm and exist in the meteorite surrounded by meteoritic silicates. Isotopic measurements of the presolar grains will likely be a diluted because of the surrounding grains. We proved that the current FIB instrumentation cannot be used to prepare presolar grains for NanoSIMS analysis. In the future, we want to use the new instrumentation (Focused Ion Beam â€“ Helios G4UX) with a superior Pt dispenser to be installed to try this technique.
Shefali Prakash & Srivatsan Swaminathan
Title: Designing A Portable Chemosensor To Measure An Alzheimer's Disease Biomarker, Methylglyoxal (MGO), in Human Blood Plasma
Faculty Advisor: Dr. Nicole Herbots
Abstract: Just in the United States of America, nearly 5.8 million individuals suffer from Alzheimerâ€™s Disease (AD). AD results in difficulty with memory and learning, and a continuous degeneration of mental functions. Currently, there is no cure for AD. Monitoring ADâ€™s progression is critical to designing an individualized treatment plan to improve patientsâ€™ quality of life and prognosis. Recently, a new biomarker for AD was identified. This biomarker is an enzyme, called Vascular Adhesion Protein-1 (VAP-1). It performs the conversion of proteins into methylglyoxal (MGO). MGO is the organic compound directly linked to neural destruction via cerebral thrombosis (i.e. formation of blood clots in the brain, a.k.a stroke), brain overstimulation, and the breakdown of a carbohydrate known as glycocalyx. The breakdown of glycocalyx results in an accumulation of the well-known beta-amyloid plaques characteristic of AD. When VAP-1 activity increases beyond normal levels, MGO levels in the plasma increase, as does a patientâ€™s risk for AD. Therefore, monitoring MGO level in patientsâ€™ blood can potentially track AD and aid in personalizing treatment options.
Presently there is no portable device to measure MGO levels in blood plasma, or MGO plasma bio-sensor. Such an MGO bio-sensor needs to be cheap, and highly accurate. The present work proposes a simple design for a portable colorimetric-based chemosensor that first, separates plasma from blood, and then accurately quantifies MGO levels, for use by patients at home, or by doctors at the point-of-care and in the field. The sensor is composed of three parts. First, a microfluidic chip separates the plasma from the rest of the blood. Next, a colorimetric reaction occurs between the MGO in the separated blood plasma and o-phenylenediamine (OPD) and citrate-capped gold nanoparticles(AuNP), which are each on two separate slides. Finally, an optical cage system (OCS) quantifies the concentration of MGO in the plasma via an LED and photodiode.
Title: Properties of Chromatin Extracted by Salt Fractionation from a Cancerous and Non-cancerous Esophageal Cell Line
Faculty Advisor: Dr. Robert Ros
Abstract: The National Institute of Health estimates that approximately 38.4% of men and women will be diagnosed with cancer at some point during their lifetimes. While cancer is mostly viewed as a genetic disease characterized by genetic markers and expression of mutant proteins, there is considerable evidence that there is more to cancer than somatic mutations. For example, the first signature looked for by a pathologist is grossly aberrant cell nuclei. It has been shown that the more abnormal a particular cell nucleus is, the more aggressive a particular form of cancer is. A major variable in the overall nuclear structure is chromatin compaction and structure. We compared chromatin compaction and structure for two esophageal cell lines, EPC2 (non-cancerous) and CP-D (cancerous) by using a combination of salt fractionation and atomic force microscopy (AFM) and found significant differences in the chromatin morphology of cancerous and non-cancerous cell lines. We anticipate that our results will help to gain insight into the mechanisms of phenotypic change in cells from normal to cancerous.
Thilina Balasooriya & Wesley Peng
Title: Fast and Furious, Accurate Blood Analysis" (FFABA) For XRF on Homogeneous Thin Solid Films (HTSF) from Blood Drops
Faculty Advisor: Dr. Nicole Herbots
Abstract: A recurring problem in comprehensive blood analysis and diagnostics is that measuring more than one component requires large volumes (2 -10 mL), often daily and sometimes on the hour in critical care. A coating combining hyper- and super-hydrophilic properties has been created to flatten and solidify blood droplets into uniform thin solid films in less than 5 minutes. Once a planar homogeneous thin solid film from a blood drop is achieved, each blood component can be analyzed using X-Ray Fluorescence (XRF) in less than 20 minutes provided an adequate substrate configuration is used via a desktop or hand-held compact XRF analyzer specifically designed for fast blood analysis. Using ÂµL sized blood drops yields an accuracy better than 10%. HemaDropâ„¢ can solidify blood droplets in less than 5 minutes in various temperatures and humidity conditions by creating Homogeneous Thin Solid Films (HTSFs) without any phase separation.
HTSFs can be analyzed in air or a vacuum because they are in the solid-state, and then analyzed using desktop X-ray Fluorescence (XRF), as well as Ion Beam Analysis (IBA). However, XRF analysis by Smart.Elementsâ„¢ simulations have been found to be inaccurate (100% error) for trace elements in blood like Fe and some blood electrolytes. Our new algorithm, Fast Hand Held Analysis of XRF - FHHAX1, is being deployed via a new mobile app called FFABA1 (Fast and Furious, Accurate Blood Analysis). The goal of the FHHAX algorithm is to perform rapid (<10 min), accurate (< 5% error ), and reliable (< 7% error ) blood analysis. Accuracy and reliability are achieved using four built-in proprietary calibration HTSFâ€™s (1) provided on every HemaDropâ„¢ collection slides. There are three collection wells(1) on each slide, allowing three measurements per test, using each 2-10 ÂµL, and determine blood electrolytes, iron and heavy metal elements, FFABA(1) is designed to provide fast interpretative results in medical laboratory format for medical practitioners in mobile app format. In the future, it will be expanded to web-based and PC-based formats.
1-Patents in Preparation with Arizona State University ABOR, and AZ Technology Entreprises/Skysong Communications (2020), Patent Agent: Patricia Stepp
1-Patents Pending Nicole Herbots, Yash Pershad, Harshini Thinakaran (2016), with Thilina Balasooriya, Nikhil Suresh, Wesley Peng, Patent Pending (2020), assigned to SiO2 Innovates LLC, MicroDrop Diagnostics"
Title: Van der Waals Interacting 2D Mo(Sx,Te1-x)2 Slab on Bulk Al2O3 Substrate
Faculty Advisor: Dr. Arunima Singh
Abstract: Two-dimensional (2D) transition metal dichalcogenides such as MoS2 and MoTe2 find attractive applications in numerous fields such as nano-electronics, catalysis and sensing. Solid-solutions of 2D MoS2 and MoTe2 offer the possibility of a systematic design of the electronic structure as a function of the chalcogen percentage, x, in the solid solution. In this work, we study the substrate-assisted stabilization of Mo(Sx,Te1-x)2 phases on Al-terminated sapphire. A cluster-expansion hamiltonian fit to first-principles simulations were used to find the ground state Mo(Sx,Te1-x)2 phases adsorbed on Al-terminated sapphire. We find that the nearest-neighbor distances of the surface sites of the Mo(Sx,Te1-x)2 phases to the sapphire substrate are larger than 2.5 Angstroms, indicating a weak van der Waals interaction between the substrate and the solid-solutions. To analyze the relationship between the ratios of S to Te in the solid-solution and binding strength to the substrate, we study the interface structure i.e. the near-interface atoms, their nearest neighbors and the distance between the nearest neighbors. We further develop heuristic measures for identifying chemisorption and physio-sorption at the interface for a particular 2D material and substrate interface.
Title: Electronic properties of 2D van der Waals magnets
Faculty Advisor: Dr. Antia Botana
Abstract: Based on first-principles calculations, the evolution of the electronic and magnetic properties of transition metal dihalides MX2 (M= V, Mn, Fe, Co, Ni; X, Y = Cl, Br, I) is analyzed from the bulk to the monolayer limit. A variety of magnetic ground states is obtained as a result of the competition between direct exchange and superexchange. We aim to show how structural symmetry-breaking plays a crucial role in the electronic properties of 2D magnetic materials with an analysis to Janus TM dihalides MXY.
Title: HemaDrop: A Novel Elemental Composition Technology for Microliter-size Blood Droplets via Solid State Techniques
Faculty Advisor: Dr. Nicole Herbots
Abstract: Blood diagnostic tests require ~7 mL of blood, taking hours for results. Repeated testing can cause Hospital-Acquired Anemia. Accurate blood testing methods with smaller blood volumes and shorter analysis time are needed.
µL-sized blood drops can be rapidly solidified via Super- and Hyper-Hydrophilic HemaDrop™ coatings to yield reproducible Homogeneous Thin Solid Films (HTSFs). HTSFs are investigated for accuracy in measuring electrolytes and heavy metals. Calibration using Balanced Saline Solution allows for the conversion of atomic % into mg/dL, the main metric in blood diagnostics. Compositions from Ion Beam Analysis and X-ray Fluorescence are compared to measure blood composition reproducibly and accurately. Relative error analysis shows that reproducibility to 10% error and accuracy to within 1% error can be attained. The damage curve method extracts elemental composition while accounting for possible IBA damage, which is found to be negligible.