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Experimental Laser Powder Bed Fusion System For Difficult To Process Metallic Materials, Syed Zia Uddin

Open Access Theses & Dissertations

The focus of this research was twofold, such as development of defect free fabrication parameters for laser powder bed fusion (LPBF) processing of crack prone or difficult to process metallic materials, and study of the temperature dependence of emissivity for some commonly used metal alloy powders in LPBF process. The later objective extends to the implementation of multiwavelength (MW) pyrometer technology for in situ true surface temperature measurement in LPBF process. LPBF is an additive manufacturing (AM) process capable of layer-by-layer manufacturing by successive laser melting of each layer according to CAD data. AM manufacturing has the inherent advantages of …

Tunable Surface Interactions In Adsorbing Polymer Solutions, Sorour Hosseini

Open Access Theses & Dissertations

A simple formalism is suggested, to calculate the most likely configuration of a finite polymer, between two surfaces on which the monomers can adsorb. Grafted polymers typically enhance the stability of colloidal dispersions, via the long ranged steric repulsion due to the overlap of their polymer brushes, which can be thicker that the typical range of the DLVO interactions. However, if the polymers are adsorbing on the colloidal surfaces, there is the possibility of bridge formation between particles and therefore long-range attractions are induced (a procedure commonly used for the flocculation of colloidal suspensions). The two effects are competing and …

Geant4 Study Of Protons - Body Interactions, Omar Hernandez Rodriguez

Open Access Theses & Dissertations

Proton beam therapy for cancer treatment uses high-energy protons to destroy cancer cells, a problem that needs immediate attention is the determination of where in the body the protons are hitting, in real time, i.e. during the irradiation. One possibility is to pay attention to the gamma rays produced during the irradiation, and use the information they carry to infer the body part that produced the gamma ray.

This Thesis presents the results of an investigation of the interaction of protons with different body parts. Focusing on gamma ray-producing interactions, the goal is to determine the type of interaction that …

Geant4 Study Of A Gamma Ray Collimator For Proton Therapy, Selim Romero

Open Access Theses & Dissertations

This Thesis presents the results of an investigation of the use of collimators in proton therapy. The problem to solve is that in the proton therapy, we do not have the certainty if the target-tumor is receiving all the energy to destroy it or if we are really shooting at this one, so the remaining question is: where the beam is hitting? How to know it? to answer those questions our work has the propose of study proton therapy to determine where the proton interactions occur, these kinds of interactions usually produce gamma rays, and we simulated in GEANT4 the …

The Hierarchical Structure Of Nanoporous Carbon Electrode Materials Elucidated By Water Sorption: A Comparison Of Multiple Structural Models, Jose Ali Espitia

Open Access Theses & Dissertations

The total amount of energy that an electrical double layer capacitor (EDLC) can store depends on the voltage and the accessible surface area for ion electrosorption. Nanoporous carbon materials with a high specific surface area, such as carbide derived carbon (CDC), make ideal electrodes for EDLC devices. CDC materials have fine-tuned pore sizes in the subnanometer range which are controlled by the initial carbide (TiC) and annealing conditions. Water can enter TiC-CDC pores and give filling fractions in excess of 0.6 g/g (H2O/C). Recent reports of water's diffusional dynamics dependence on CDC pore size indicate confinement effects similar to that …

The Inverse And Direct Hofmeister Series Of Hen Egg White Lysozyme At Ph Below The Isoelectric Point (Pi) As Seen By Small Angle X-Ray Scattering(Saxs), Pawan Koirala

Open Access Theses & Dissertations

The structural changes of Hen Egg White Lysozyme (HEWL) in the intermediate stages leading up to Hofmeister anion-induced aggregation were measured using small-angle x-ray Scattering (SAXS). We used three concentrations of HEWL: 10mg/ml, 60mg/ml and 200mg/ml and two concentrations of salts: 0.1M and 1.0M, mostly in a Tris-buffer solution with a pH of 9.0. For 200mg/ml in Di-water solution, the scattering signal was best fit using an ellipsoidal form factor with equatorial radius of 28.4±0.1 Å and polar radius of 11.3±0.1 Å, and a screened Coulomb repulsive structure factor with an effective radius of 19.9±0.1 Å and protein surface charge …

Gravitational Waves Research At Toros Utrgv, Pamela Ivonne Lara

Open Access Theses & Dissertations

The detection of gravitational waves (GW) has directly opened a new era in the observation of cosmic events. One hundred years after its theoretical prediction we find ourselves immerged in the multi-messenger study of the signals at the root of gravitational wave detection. The electromagnetic (EM) counterpart to GW is the optical portion of that signal and the main objective in the organization of TOROS Collaboration: finding and studying kilonovas, the name given by Metzger (Metzger et al, 2010), to the EM counterpart to gravitational waves.

In order for TOROS to find kilonovas, it needed to create a python language …

Magnetic And Catalytic Properties Of Transition Metal Doped Mos2 Nanocrystals, Luis Martinez

Open Access Theses & Dissertations

Magnetism and catalytic activity of nanoscale layered two-dimensional (2D) transition metal dichalcogenides (TMDs) have gained an increasing research interest in the recent past. To broaden the current knowledge and understanding on this subject, in this work, together with my collaborators, I study the magnetic and electrocatalytic properties of hydrothermally grown pristine and transition metal doped (10% of Co, Ni, Fe and Mn) 2H-MoS2 nanosheets/nanocrystals (NCs), with the particle size of 25-30 nm. A broad range of experimental measurements such as x-ray diffraction, transmission electron microscopy, x-ray photo absorption spectroscopy, Raman spectroscopy, magnetic, catalytic and electron spin resonance have been employed …