Digital Commons Network^™

Case Studies In Disassembly Process Planning, Riteshkumar Dhimmar

Theses

The rapid advancement in technology started in last century and still continuing resulted in decreased life cycle of electronic products. It also resulted in increased product disposal rate and filling land fill space faster causing shortage of such space and consequently creates major environmental problems. So, since couple of decade environmental concern has focused on production process and environmental regulations imposed by government has watched industrial pollution. With government regulations to control environmental problems; consumers are also aware of adverse effects of product disposal forcing manufacturer to become more responsible for safe product disposal and recycling of used product.

A …

Evaluation Of Effect Of Extrusion Process Variables On Mechanical Properties Of Extruded Collagen Tubes And Effect Of Post Extrusion Treatments, Mayank K. Patel

Theses

This study evaluated the effect of extrusion process variable on mechanical properties of extruded collagen tubes made using a specialized extruder, made by ZOKO Corporation of Czechoslovakia. Three extrusion variables were considered; extrusion speed, linear draw rate and rotation speed. Using Taguchi L₄ matrix, a design of experiment (DOE) was run. Two mechanical properties, wall thickness and estimated elastic modulus, were considered as response of this DOE. Data was analyzed statically to evaluate the effect of extrusion variables on both these properties. Result of this study showed that linear draw rate of the extrusion process has the highest influence …

Biomimetic Sensor For In-Vivo Applications, Daya I. Sooryadas

Theses

The development of sensitive specific devices (e.g., molecular sensors) for the detection, diagnosis and monitoring of diseases, drug discovery, environmental detection of pollutants and/or biological agents has been an active area of research. A molecular sensor is a biomolecule or biomimetic molecule that performs two distinct functions in detecting target molecules. The sensor molecule recognizes a target molecule and specifically binds to it. This specific binding generates a signal in response to the event of target binding that can be then detected. The long term vision of this thesis research work is to develop a specific recognition ligand for detecting …

Measurement Of The Effectiveness Of Enhanced External Counterpulsation On Heart Rate Variability For Patients With Myocardial Ischemia, Kripa Jayaraman

Theses

This thesis is a study to measure the changes in heart rate variability due to the activity of the autonomic nervous system caused by the Enhanced External Counterpulsation treatment. The treatment is a non surgical, mechanical procedure that can reduce the symptoms of angina or Congestive Heart Failure, presumably by stimulating the opening, or formation of, small branches of blood vessels (collaterals) to create a natural bypass around narrowed or blocked arteries. It has been proved that rhythms can be markers of normal functional states. Even in the absence of external perturbations, the normal heartbeat is not characterized by clockwise …

Mathematical Modeling And Simulation Of Human Motion Using 3-Dimensional, Multi-Segment Coupled Pendulum System : Derivation Of A Generalized Formula For Equations Of Motion, Loay Ahmed-Wasfe Al-Zube

Theses

The use of mathematical models to investigate the dynamics of human movement relies on two approaches: forward dynamics and inverse dynamics. In this investigation a new modeling approach called the Boundary Method is outlined. This method addresses some of the disadvantages of both the forward and the inverse approach. The method yields as output both a set of potential movement solutions to a given motor task and the net muscular impulses required to produce those movements. The input to the boundary method is a finite and adjustable number of critical target body configurations. In each phase of the motion that …

An In Vitro Evaluation Of Tyrosine Derived Polyarylates And Polycarbonate As Polymeric Scaffold For Human Mesenchymal Stem Cells Osteogenic Differentiation, Manish Suresh Godbole

Theses

Human mesenchymal stem cells (hMSCs) obtained from the adult bone marrow are multipotential cells that are capable of differentiating along several lineages. They are readily available and abundant source of cells in the field of tissue engineering. For their use in treating certain connective tissue defect or disorders, their success depends at minimum on the use of scaffolds that support differentiation. Therefore , this thesis details a study that systematically evaluated hMSC differentiation on materials that exhibit gradual range in surface properties as a first study for selecting materials as potential scaffolds. Polycarbonates and polyarylates have combinatorial libraries that exhibit …

Characterization Of Electrospun Dlplga Nanofibers For A Drug Delivery System For Intracranial Tumors And Avms, Kimberly A. Griswold

Theses

Electrospinning processes apply electric fields to a polymer solution in order to produce strands of polymer in the nanoscale range. These polymer fibers are manipulated for their porosity, high surface area, fineness and uniformity. In order to create the ideal drug delivery system for intracranial arteriovenous malformations (AVMs) and tumors, D, L poly-(lactice-poly-glycolide) (DLPLGA) nanofibers were electrospun in a tetrahydrofuran (THF) solvent. Three different concentration ratios of DLPLGA, 85/15, 80/20, and 75/25 were analyzed to obtain the prime base for drug annexation. 1 ,3-bis (2-chloroethyl)- 1 -nitrosourea (BCNU) was then codissolved with the DLPLGA nanofibers to form a homogenous solution, …

Design And Implementation Of Heart Rate Variability Measures In The Time Domain, Binoy John Mathews

Theses

The following study was conducted to design and implement computer programs to derive five time domain and two frequency domain Heart Rate Variability (HRV) measures from 24 hour Holter monitor recordings and to generate activity plots that display the variation of three of the five time domain measures and two frequency domain measures over a period of 24 hours.

Working with known pre and post experimental ECG data taken from a cyclical exercise program, standard parameters in both the time and frequency domains were derived using programs designed in Labview 7.0 engineering software package. Five parameters in the time domain …

Extrusion And Evaluation Of Degradation Rate And Porosity Of Small Diameter Collagen Tubes, Bipinkumar G. Patel

Theses

The limited availability of autografts and failure of small diameter synthetic vascular grafts has stimulated continuing efforts to develop small diameter vascular grafts based on natural materials. The small diameter collagen tubes were extruded using bovine collagen type I. The biodegradation rate was determined and compared for small diameter collagen tubes crosslinked with glutaraldehyde and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and Nhydroxysuccinimide (NHS) to evaluate physio-chemical properties. The samples were also evaluated for their surface area and porosity using mercury porosimeter. The noncrosslinked tubes almost completely degraded after 2 hours. The tubes crosslinked with EDC/NHS degraded slower than the ones crosslinked with …

Particle Size Dependence On Immobilized Molecular Sensors : Assay Of Nucleic Acid Probes Attached To Paramagnetic Particles, Celin Sunny

Theses

Nanotechnology is concerned with materials and systems whose structure and components exhibit novel and significantly improved physical, chemical and biological properties, phenomena and processes due to their nano scale size.

The transition from micro scale to nano scale leads to a number of changes in physical properties, possibly including new physical principles, some of which may be yet to be discovered. One of the major factors in this is the increase in ratio of surface area to volume.

This thesis research uses the increase in ratio of surface area to volume property of going from macro to micro to nano …

Spinning Of Collagen Fibers And Characterizing Thermal, Mechanical, Tensile And Structural Properties, Grace Evangelin Tatagiri

Theses

Collagen is the most important building block in the entire animal world. It plays an important role in regeneration of broken bones and wound healing, also helps grow blood vessels to feed the healing areas. The use of synthetic materials has been extensive, but these materials have there own limits and drawbacks. Poor biocompatibility of these materials is the main issue and often result in inflammations. Hence collagen is being heralded as one of the most appropriate replacement as an implantable material. The reasons being that it is a naturally occurring material, exhibits high biocompatibility low antigenicity and host response. …

Mathematical Modeling Of Transient State Transdermal Drug Delivery, Alison Nickol Weltner

Theses

In this work, a two-pathway mathematical model for transdermal drug delivery with iontophoresis is presented. The partial differential equations are described and then solved. An alternative, two-pathway, three-layer model is also presented, and the implications of the coefficients within the equation are discussed. Using Franz cell iontophoretic delivery data from three drug substances (amitriptyline HCl, clomipramine HCl, and nortriptyline HCl), the two-pathway model is regressed to determine the diffusion coefficient and the concentration within the skin at the drug reservoir interface. ANOVA analysis indicates a correlation between iontophoretic current and concentration of drug within the stratum corneum.

Growth And Transport Properties Of Complementary Germanium Nanowire Field Effect Transistors, Andrew B. Greytak, Lincoln J. Lauhon, Mark S. Gudiksen, Charles M. Lieber

Faculty Publications

n- and p-type Ge nanowires were synthesized by a multistep process in which axial elongation, via vapor–liquid–solid (VLS) growth, and doping were accomplished in separate chemical vapor deposition steps. Intrinsic, single-crystal, Ge nanowires prepared by Au nanocluster-mediated VLS growth were surface-doped in situ using diborane or phosphine, and then radial growth of an epitaxial Ge shell was used to cap the dopant layer. Field-effect transistors prepared from these Ge nanowires exhibited on currents and transconductances up to 850 µA/µm and 4.9 µA/V, respectively, with device yields of >85%.

Effect Of Silicon Content On The Corrosion Resistance And Radiation-Induced Embrittlement Of Materials For Advanced Heavy Liquid Metal Nuclear Systems, Ajit K. Roy

Transmutation Sciences Materials (TRP)

The purpose of this collaborative research project involving the University of Nevada Las Vegas (UNLV), Los Alamos National Laboratory (LANL) and Idaho State University (ISU) is to evaluate the effect of silicon (Si) content on the corrosion behavior and radiation-induced embrittlement of martensitic stainless steels having chemical compositions similar to that of the modified 9Cr-1Mo 2 steel. Recent studies at LANL involving Alloy EP-823 of different Si content have demonstrated that increased Si content in this alloy may enhance the corrosion resistance in molten lead-bismuth-eutectic (LBE). Since very little data exists in the open literature on the beneficial effect of …

Biological Feasibility And Optimization Of Biosparging At A Hydrocarbon-Contaminated Site, Jason G. Waudby, Yarrow M. Nelson

Civil and Environmental Engineering

The purpose of this study was to identify any biological/chemical factors which may be limiting the biodegradation of total petroleum hydrocarbon (TPH) contaminants at a biosparge site located at a former oil field near Guadalupe, California. Laboratory experiments using a combination of respirometry and TPH analyses were conducted to determine if biodegradation of TPH at the site is limited by a lack of hydrocarbon-degrading microorganisms, depleted inorganic nutrient concentrations, insufficient dissolved oxygen supply, or the chemical composition of the partially biodegraded petroleum constituents in the groundwater. No increase in total CO₂ production was observed in samples with added nutrients, …

Biodegradability And Toxicity Of Hydrocarbon Leachate From Land Treatment Units, Sandy L. Scott, Yarrow M. Nelson

Civil and Environmental Engineering

The biodegradability of leachate from the land treatment of hydrocarbon-contaminated soil was investigated in the laboratory using respirometry and toxicity testing in combination with total petroleum hydrocarbon (TPH) measurements. Soil in land treatment units (LTU) had been contaminated with a diesel-like hydrocarbon mixture formerly used as a diluent for crude oil at an oil field in California. Leachate was collected from two different LTUs for treatability testing in a respirometer under aerobic conditions. Only about 12% reduction in TPH concentration was observed after aeration for 161 days, indicating limited biodegradability of the hydrocarbon constituents in the leachate. Similarly, Microtox® toxicity …

Geometry Of Protein Structures. I. Why Hyperbolic Surfaces Are A Good Approximation For Beta-Sheets, Boguslaw Stec, Vladik Kreinovich

Departmental Technical Reports (CS)

Protein structure is invariably connected to protein function. To analyze the structural changes of proteins, we should have a good description of basic geometry of proteins' secondary structure. A beta-sheet is one of important elements of protein secondary structure that is formed by several fragments of the protein that form a surface-like feature. The actual shapes of the beta-sheets can be very complicated, so we would like to approximate them by simpler geometrical shapes from an approximating family. Which family should we choose? Traditionally, hyperbolic (second order) surfaces have been used as a reasonable approximation to the shape of beta-sheets. …

Fuzzy And Probabilistic Models Of Association Information In Sensor Networks, Leon Reznik, Vladik Kreinovich

Departmental Technical Reports (CS)

The paper considers the problem of improving accuracy and reliability of measurement information acquired by sensor networks. It offers the way of integrating sensor measurement results with association information available or a priori derived at aggregation nodes. The models applied for describing both sensor sensor results and association information are reviewed with consideration given to both neuro-fuzzy and probabilistic models and methods. The information sources, typically available in sensor systems, are classified according to the model (fuzzy or probabilistic), which seems more feasible to be applied. The integration problem is formulated as an optimization problem.

The Influence Of Environmental Temperature And Substrate Initial Moisture Content On Aspergillus Niger Growth And Phytase Production In Solid−State Cultivation, Seaborn B. Carter, Sue E. Nokes, Czarena L. Crofcheck

Biosystems and Agricultural Engineering Faculty Publications

Aspergillus niger is being used commercially for phytase production utilizing solid-state cultivation; however, no studies have been published that investigated the optimal environmental temperature and initial substrate water content to maximize fungal growth and/or phytase production. Solid-state cultivations of Aspergillus niger on wheat bran and soybean meal were conducted at three temperatures (25°C, 30°C, and 35°C) and three initial moisture contents (50%, 55%, and 60% wet basis) in a split-plot full-factorial experimental design. Fermentations were conducted for 0, 24, 48, 72, and 120 h. The containers were sampled destructively and assayed for phytase activity and glucosamine concentration as an estimate …

Transdermal Delivery Of Phosphorodiamidate Morpholino Oligomers Across Hairless Mouse Skin, Angela K. Pannier, Vikram Arora, Patrick L. Iversen, Rhonda M. Brand

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The skin is the largest organ in the body and an obvious route for both local and systemic drug delivery. Antisense oligomers have tremendous potential as therapeutic agents for numerous diseases. The objective of this study was to investigate the influence of vehicle on the transdermal delivery of several phosphorodiamidate Morpholino oligomers (PMOs) with different sizes, lengths, base compositions, sequences, and lipophilicities. Eleven different PMOs were synthesized complementary to biologically relevant gene targets and delivered across hairless mouse skin in vitro using vehicles composed of 95% propylene glycol, 5% linoleic acid (PG/LA), water, 50% water:50% PG/LA, and 75% water:25% PG/LA. …

Field Calibration Of The Float Method In Open Channels, Jorge Escurra

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Surface velocity coefficients were calculated at five locations in three different irrigation canals in Logan, Utah. First, the total flow' rate was measured using current meters and calculated cross-sectional flow area. Second , the surface velocity was measured using four trials of the float method , and the average float travel time was calculated for each location and measurement instance. The measurements were taken on different days for various water depths in the canals. Third, the surface and mean cross-sectional velocities were divided , yielding the surface velocity coefficient, for every measurement at each of the five locations. Several channel …

Bulk Polymerization And Structure-Property Relationship Of Medical Grade Polyurethane, Mariam Nasser Al-Saedi

Theses

Polyurethanes as biomaterials have been used in the augmentation and repair of the human body with great success. The choice of material for a particular application often hinges on the body's response to the polymer, the mechanical and thermal properties of the polymer and the stoichiometric ratio of active ingredients used in the synthesis.

A large number of polyurethanes used in medical applications are polyester-based and cannot be used in long-term implant applications because they are very susceptible to hydrolysis. Other medical-grade polyurethanes, which are suitable for implants are polyether-based which might to some extent, suffer from environmental stress cracking …

Processing And Optimization Of Natural Fiber Reinforced Composites Using Date Palm Fibers, Khalifa Musabbeh Suwaidan Hamad Al-Kaabi

Theses

During the last twenty years, ecological concerns have resulted in a renewed interest in natural materials. Composite materials usually depend on using man-made fibers as the reinforcing element. The possibility of using natural fibers instead of synthetic fibers is gaining acceptance among users. This work aims to investigate the possibility of extracting natural fibers from date palm trees to be used as reinforcement with polymeric materials. The objective was achieved by characterizing fibers through different chemical, physical and mechanical tests and using different treatment methods in order to modify the fiber properties. Date Palm Fibers (DPF) exhibit a cylindrical shape …

Inside Unlv, Gian Galassi, Andy Grossman, Donna Mcaleer, Jennifer Vaughan, Carol C. Harter, Ronald Yasbin

Inside UNLV

No abstract provided.

Use Of Positron Annihilation Spectroscopy For Stress-Strain Measurements, Ajit K. Roy

Transmutation Sciences Materials (TRP)

The purpose of this collaborative research project involving the University of Nevada Las Vegas (UNLV) and Idaho State University (ISU) is to evaluate the feasibility of determining residual stresses of welded, bent (three-point-bend), and cold-worked engineering materials using a new nondestructive technique based on positron annihilation spectroscopy (PAS). The proposed technique is to use γ-rays from a small MeV electron linear accelerator (Linac) to generate positrons inside the test sample via 2 pair production. This method can be used for materials characterization and investigation of defects in thick samples that usually cannot be accomplished by conventional positron technique or other …

Noble Metal Nanostructures Synthesized Inside Mesoporous Nanotemplate Pores, J. Arbiol, E. Rossinyol, A. Cabot, F. Peiro, A. Cornet, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Noble metal impregnation has resulted in the inclusion of metal nanostructures within the SBA-15 mesoporous silica hexagonal pores (from nanoclusters to nanowires). A bright-field transmission electron microscopy three-dimensional reconstruction is proposed to analyze the localization of nanostructures within the pores of mesoporous nanotemplates. The method allows corroboration whether the nanostructures are synthesized inside the pores or they are synthesized alternatively on the nanotemplate aggregates exterior surface.

Developing A Sensing System For The Measurement Of Oxygen Concentration In Liquid Pb-Bi Eutectic, Bingmei Fu, Yingtao Jiang, Jian Ma

Mechanical Engineering Faculty Research

Although liquid lead-bismuth eutectic (LBE) is a good candidate for the coolant in the subcritical transmutation blanket, it is known to be very corrosive to stainless steel, the material of the carrying tubes and the containers. Such a corrosion problem can be prevented by producing and maintaining a protective oxide layer on the exposed surface of stainless steel. The proper formation of this oxide layer critically depends on the accurate measurement and control of the oxygen concentration in the liquid LBE. YSZ (Yttria Stabilized Zirconia) oxygen sensors, using molten bismuth saturated with oxygen as the reference, have been utilized to …

Molecular-Dynamics Simulation Of The Effect Of Ions On A Liquid–Liquid Interface For A Partially Miscible Mixture, Richard L. Rowley, Kent E. Wardle, Eric Carlson, Douglas Henderson

Faculty Publications

Molecular-dynamics simulations were performed to model the effect of added salt ions on the liquid-liquid interface in a partially miscible system. Simulations of the interface between saturated phases of a model 1-hexanol + water system show a bilayer structure of 1-hexanol molecules at the interface with OH heads of the first layer directed into the water phase and the opposite orientation for the second layer. The alignment of the polar OH groups at the interface stabilizes a charge separation of sodium and chloride ions when salt is introduced into the aqueous phase, producing an electrical double layer. Chloride ions aggregate …

2004 - The Ninth Annual Symposium Of Student Scholars

Symposium of Student Scholars Program Books

The full program book from the Ninth Annual Symposium of Student Scholars, held on April 16, 2004. Includes abstracts from the presentations and posters.

Strutural Damage Induced By Pyritic Shale, Shad E. Hoover, Mian C. Wang, Brian Dempsey

International Conference on Case Histories in Geotechnical Engineering

The Evangelical Hospital located in Lewisburg, Pennsylvania has experienced distress in the form of cracked floor slabs and displaced structural steel due to swelling of the underlying fill material and natural bedrock formation. The bedrock consisted of black, pyritic, calcareous shale from the Marcellus Formation of the Hamilton Group (Devonian Age). The fill materials beneath the cracked concrete floor slabs consisted of the weathered shale fragments from this formation. Although mitigating the structural distress has been attempted, the building continued to experience problems relating to the swelling of the underlying bedrock materials. The expansion of the shale could be attributed …