Interfacial chemical bonding-mediated ionic resistive switching.

In this paper, we present a unique resistive switching (RS) mechanism study of Pt/TiO2/Pt cell, one of the most widely studied RS system, by focusing on the role of interfacial bonding at the active TiO2-Pt interface, as opposed to a physico-chemical change within the RS film. This study was enabled by the use of a non-conventional scanning probe-based setup. The nanoscale cell is formed by bringing a Pt/TiO2-coated atomic force microscope tip into contact with a flat substrate coated with Pt. The study reveals that electrical resistance and interfacial bonding status are highly coupled together. An oxygen-mediated chemical bonding at the active interface between TiO2 and Pt is a necessary condition for a non-polar low-resistance state, and a reset switching process disconnects the chemical bonding. Bipolar switching mode did not involve the chemical bonding. The nature of chemical bonding at the TiO2-metal interface is further studied by density functional theory calculations

Machine Learning Algorithm for Early Detection and Analysis of Brain Tumors Using MRI Images

Among the human body's organs, the brain is the most delicate and specialized. It is proven that after the heart stops then also brain death occurs within 3 to 5 minutes of death or within 3 to 5 minutes of loss of oxygen supply. A brain tumor is a life-threatening disease that can be detected at any age from an infant to an old person. Though a lot of people did research in the detection and analysis of a tumor, but then also detecting tumors at the early phase is still a much more arduous field in the biomedical study. This paper focuses on the comparative study of various existing algorithms in this field. This paper addresses the challenges and some issues in MRI brain tumor detection which are also addressed in this research

Effect Of Dopants On The Properties And Performance Of Gallium Oxide: Bulk Ceramics And Nanomaterials

A comprehensive investigation performed in order to understand the fundamental aspects of transition metal (TM) incorporation into Ga2O3, a wide band gap semiconductor with a huge potential for application in electronics, optics, micromechanics and optoelectronics. An approach is presented to tailor the structural, optical, electrical, mechanical properties of Ga2O3 ceramics and thin films. The tungsten (W) mixed Ga2O3 with variable W at% (Ga2-2xWxO3 ; 0.00 ≤ x ≤ 0.30) were synthesized by the high temperature solid state route involving a 2-step calcination process. The solubility limits and phase stability of the compounds are established. While solubility and phase stability occur for x ≤ 0.10 at%, additional TM-content alters the morphology from rod-shape to spherical shape with undissolved TM giving the researchers a scope to alter properties with the inclusions. A bandgap variation is also observed at higher concentrations of TM in the system giving rise to either a single edge absorption in case of WO3 and double edge absorption in case of TiO2. In both case for the TM inclusion, a red shift is observed in the band gap giving an interesting platform to approach device fabrication for optical materials. This work also demonstrates an approach towards the practical application of Ga2O3 materials in the form thin films. The strength of thin films deposited using the pulsed laser deposition (PLD) unit is also reported. The depositions were done at higher temperature and an attempt was made to study the optical property variation with the deposition temperature. This direction was taken in this current work to study how the materials will behave at extreme temperatures if the devices were used in harsh environment. The hardness of the thin films improved with the temperature due to the high temperature kinetics which also improved the grain size giving a compact system at 700 ℃. An attempt has been made to establish the structure-property correlation, which may be useful for practical applications of Ga2O3 PLD thin films

Smart Sensors to Reduce Pollutant Emissions in Transportation

Final ReportDoped perovskite materials exhibiting temperature independent conductivity has gained enormous attention for high temperature oxygen sensors due to great advantage over traditional doped metal oxides. This report focused on effect of sintering temperature on structure, morphology to explore correlation between oxygen sensing response of Ba(Fe0.7Ta0.3)O3-δ (BFTO30) bulk ceramics with structural and morphological features. Conventional solid-state reaction was used to synthesize BFTO30 powders. Crystal symmetry and phase purity of calcined and sintered powders was confirmed through X-ray diffraction analysis. Calcination of homogenous mixed precursors confirms that a single-phase perovskite phase without any secondary phases was obtained at 1150 °C. Samples were sintered at different temperatures (1200 °C, 1250 °C, 1300 °C, 1350 °C), X-ray diffraction of sintered samples reveals that there is a clear structural transformation from low symmetry rhombohedral phase to high symmetry cubic phase with temperature. Sintered samples exhibit porous morphological features with samples sintered at ≤1300 °C, whereas samples sintered at 1350 °C exhibits dense morphology with nearly spherical grains.U.S. Department of Transportation 69A355174711

A Study of Rolling Resistance of Electrorheological Fluids Impregnated Polymers as a Function of Electric Field

Rolling resistance contributes to 6-10% of the overall fuel consumption. In an effort to provide tunable rolling resistance and tunable damping rubbers, smart fluids are introduced to composites to fabricate smart composites. The subsequent composites will possess unique mechanical properties in response to an externally applied voltage. This paper discusses the measurement of rolling resistance of poly(vinylidene fluoride) (PVDF) using a wooden pendulum roller, crafted in our lab. All fibers can be submerged in the electro rheological fluids (ERF) and become impregnated with barium titanyl oxalate with urea coated particles. Under the influence of electric field strength, the properties such as damping coefficient, rolling force and viscoelastic properties are altered. A comparison between the properties of different PVDF samples was made. PVDF3 with 0.17 g/ml concentration is best aligned and shows the highest change in properties as a function of electric field strength

Smart Sensors to Reduce Pollutant Emissions in Transportation, Phase II

Final ReportThe proposed project is intended to design, develop, characterize, and demonstrate the feasibility of oxide materials based sensors, which are compatible for high temperature operation and efficient in functionality in a wide range of pressures that encountered in engines, for utilization in next generation, advanced transportation systems. The goal is to design and develop oxide sensing elements, evaluate their performance and demonstrate the relative merits of sensor elements based on hybrid nanostructures of economically viable materials for application in internal combustion engines of automotive industry. In this work, the Ba-Fe containing perovskites are engineered to serve the high-temperature and harsh environments of vehicle technologies while reducing the pollutant emissions. Doped perovskite materials exhibiting temperature independent conductivity has gained enormous attention for high temperature oxygen sensors due to great advantage over traditional doped metal oxides. This report focused on effect of sintering temperature on structure, morphology to explore correlation between oxygen sensing response of Ba(Fe0.7Ta0.3)O3-δ (BFTO30) bulk ceramics with structural and morphological features. Conventional solid-state reaction was used to synthesize BFTO30 powders. Crystal symmetry and phase purity of calcined and sintered powders was confirmed through X-ray diffraction analysis. Calcination of homogenous mixed precursors confirms that a single-phase perovskite phase without any secondary phases was obtained at 1150 °C. Samples were sintered at different temperatures (1200 °C, 1250 °C, 1300 °C, 1350 °C), X-ray diffraction of sintered samples reveals that there is a clear structural transformation from low symmetry rhombohedral to high symmetry cubic phase with temperature. Sintered samples exhibit porous morphological features with samples sintered at ≤1300 °C, whereas samples sintered at 1350 °C exhibits dense morphology with nearly spherical grains.U.S. Department of Transportation 69A355174711

The prevalence of sickle cell disease phenotypes and sickle cell gene frequency in some tribals of Melghat forest region of Amravati,

Abstrac

Direct Deoxygenation of α‑Hydroxy and α,β-Dihydroxy Ketones Using a Silyl Lithium Reagent

A reliable method for the one-step direct deoxygenation of α-hydroxy ketones has been developed using a silyl lithium reagent and acetic anhydride. The method is metal-catalyst-free and does not require prefunctionalization of the hydroxy group prior to its removal. Deoxygenation of different primary, secondary, and tertiary alcohols was carried out with up to 98% isolated yield. Additionally, double deoxygenation was achieved when the present method was applied to α,β-dihydroxy ketones to access the corresponding enones in a single step

Interfacial chemical bonding-mediated ionic resistive switching.

In this paper, we present a unique resistive switching (RS) mechanism study of Pt/TiO2/Pt cell, one of the most widely studied RS system, by focusing on the role of interfacial bonding at the active TiO2-Pt interface, as opposed to a physico-chemical change within the RS film. This study was enabled by the use of a non-conventional scanning probe-based setup. The nanoscale cell is formed by bringing a Pt/TiO2-coated atomic force microscope tip into contact with a flat substrate coated with Pt. The study reveals that electrical resistance and interfacial bonding status are highly coupled together. An oxygen-mediated chemical bonding at the active interface between TiO2 and Pt is a necessary condition for a non-polar low-resistance state, and a reset switching process disconnects the chemical bonding. Bipolar switching mode did not involve the chemical bonding. The nature of chemical bonding at the TiO2-metal interface is further studied by density functional theory calculations

Scanning probe-based in situ high temperature electrical and electrochemical measurements in atmospheric pressure

Atomic force microscopy (AFM)-based study of electrical and electrochemical properties of a material/system at an elevated temperature in atmospheric pressure has been limited to ~250°C in conventional AFM setups. In this report, we have demonstrated the viability of a new approach for high temperature electrical and electrochemical studies (up to 700°C) in a conventional AFM setup by employing a combination of a micron-scale heater stage (MHS) and custom-made all-metal tips. We present the design, fabrication process and characterization of the MHS and all-metal tips. A temperature dependent impedance measurement on an MHS-integrated half-cell was then successfully demonstrated with a custom-made Pt-Ir tip. Issues and possible room to improve regarding the new approach are also discussed.MOE (Min. of Education, S’pore)Published versio