Students performed Rutherford back scattering (RBS) experiments using 1.5 MeV helium ion (+1) bea... more Students performed Rutherford back scattering (RBS) experiments using 1.5 MeV helium ion (+1) beam from a Van de Graaff accelerator. The ion beam was incident normally on target samples located in a scattering chamber. The samples were single and multilayered thin films on substrate, prepared using a vacuum evaporator. The scattered ions were measured using a particle detector located at 150° from incident beam direction. The elastically scattered particle energies were predicted from kinematical scattering factor (derived using conservation of energy and momentum) and experimentally verified. Using samples of known elemental thicknesses, the data was normalized and thicknesses of layers in unknown samples determined. For multilayer samples, the scattered particle spectra were analyzed for particle yield per ion, energy shift in the centroid and energy at the leading edge for the elemental peak. The Rutherford scattering formula and the kinematical scattering factor together with the energy loss of the helium ion through the various layers were used to identify elemental layers, their positions and thicknesses. The multilayer films were identified as gold-tungsten-tin (Au-W-Sn). The normalization procedure allowed the thicknesses to be determined with uncertainties of a few percent.
In microscopy the question arises- Why employ electron beams instead of light beams to produce ma... more In microscopy the question arises- Why employ electron beams instead of light beams to produce magnified images and the answer has to do with resolution. When doing microscopy to produce magnified image of objects, diffraction (bending of waves around narrow openings and obstacles) limits the resolution and hence the quality of image in terms
Changes in elemental composition and mechanical properties of leg bones were determined following... more Changes in elemental composition and mechanical properties of leg bones were determined following hind-limb suspension (HLS) and irradiation of rats and mice. Tibia and Femur were bent with an applied force and corresponding elastic modulus determined. The bones were cross sectioned for elemental composition using Scanning Electron Microscopy with Energy Dispersive capabilities (EDX). The effect of microgravity on bones was evident after 4 days of suspension. There was a strong relationship between the compositional ratios of calcium, carbon, phosphorus and oxygen with the location on the leg. Two methods were used to measure mechanical strength of the bones; a LASER based bending setup (Cantilever) and a 3-point bending setup with sensor to measure bending steps and stepping mechanism. Results showed that the femur bones had Young's modulus between 6 and 18 GN/m. For control groups, it was ~2.5 times larger than that for the HLS group. This clearly points to a less elastic nature of leg bones exposed to ...
Learn how the multidisciplinary BioNanoTox Conference brings together various disciplines encompa... more Learn how the multidisciplinary BioNanoTox Conference brings together various disciplines encompassing biology, chemistry, toxicology, computational sciences, mathematics, physics, engineering, and nanotechnology. BioNanoTox (Biology, Nanotechnology, and ...
ENHANCING THE UNDERGRADUATE EXPERIENCE: ATOMIC AND NUCLEAR PHYSICS EXPERIMENTS AT AN ACCELERATOR ... more ENHANCING THE UNDERGRADUATE EXPERIENCE: ATOMIC AND NUCLEAR PHYSICS EXPERIMENTS AT AN ACCELERATOR FACILITY. [AIP Conference Proceedings 1099, 234 (2009)]. Rahul Mehta, Stephen R. Addison, Jerome L. Duggan. Abstract. ...
Microgravity has profound effects on skeletal as well as other body systems. To investigate the e... more Microgravity has profound effects on skeletal as well as other body systems. To investigate the effect of microgravity, we have used a NASA validated Hind‐limb suspension (HLS) animal model of simulated weightlessness. Groups of mice and rats were subjected to hind limb ...
Students performed Rutherford back scattering (RBS) experiments using 1.5 MeV helium ion (+1) bea... more Students performed Rutherford back scattering (RBS) experiments using 1.5 MeV helium ion (+1) beam from a Van de Graaff accelerator. The ion beam was incident normally on target samples located in a scattering chamber. The samples were single and multilayered thin films on substrate, prepared using a vacuum evaporator. The scattered ions were measured using a particle detector located at 150° from incident beam direction. The elastically scattered particle energies were predicted from kinematical scattering factor (derived using conservation of energy and momentum) and experimentally verified. Using samples of known elemental thicknesses, the data was normalized and thicknesses of layers in unknown samples determined. For multilayer samples, the scattered particle spectra were analyzed for particle yield per ion, energy shift in the centroid and energy at the leading edge for the elemental peak. The Rutherford scattering formula and the kinematical scattering factor together with the energy loss of the helium ion through the various layers were used to identify elemental layers, their positions and thicknesses. The multilayer films were identified as gold-tungsten-tin (Au-W-Sn). The normalization procedure allowed the thicknesses to be determined with uncertainties of a few percent.
In microscopy the question arises- Why employ electron beams instead of light beams to produce ma... more In microscopy the question arises- Why employ electron beams instead of light beams to produce magnified images and the answer has to do with resolution. When doing microscopy to produce magnified image of objects, diffraction (bending of waves around narrow openings and obstacles) limits the resolution and hence the quality of image in terms
Changes in elemental composition and mechanical properties of leg bones were determined following... more Changes in elemental composition and mechanical properties of leg bones were determined following hind-limb suspension (HLS) and irradiation of rats and mice. Tibia and Femur were bent with an applied force and corresponding elastic modulus determined. The bones were cross sectioned for elemental composition using Scanning Electron Microscopy with Energy Dispersive capabilities (EDX). The effect of microgravity on bones was evident after 4 days of suspension. There was a strong relationship between the compositional ratios of calcium, carbon, phosphorus and oxygen with the location on the leg. Two methods were used to measure mechanical strength of the bones; a LASER based bending setup (Cantilever) and a 3-point bending setup with sensor to measure bending steps and stepping mechanism. Results showed that the femur bones had Young's modulus between 6 and 18 GN/m. For control groups, it was ~2.5 times larger than that for the HLS group. This clearly points to a less elastic nature of leg bones exposed to ...
Learn how the multidisciplinary BioNanoTox Conference brings together various disciplines encompa... more Learn how the multidisciplinary BioNanoTox Conference brings together various disciplines encompassing biology, chemistry, toxicology, computational sciences, mathematics, physics, engineering, and nanotechnology. BioNanoTox (Biology, Nanotechnology, and ...
ENHANCING THE UNDERGRADUATE EXPERIENCE: ATOMIC AND NUCLEAR PHYSICS EXPERIMENTS AT AN ACCELERATOR ... more ENHANCING THE UNDERGRADUATE EXPERIENCE: ATOMIC AND NUCLEAR PHYSICS EXPERIMENTS AT AN ACCELERATOR FACILITY. [AIP Conference Proceedings 1099, 234 (2009)]. Rahul Mehta, Stephen R. Addison, Jerome L. Duggan. Abstract. ...
Microgravity has profound effects on skeletal as well as other body systems. To investigate the e... more Microgravity has profound effects on skeletal as well as other body systems. To investigate the effect of microgravity, we have used a NASA validated Hind‐limb suspension (HLS) animal model of simulated weightlessness. Groups of mice and rats were subjected to hind limb ...
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