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Silicon Carbide/Electroless Nickel Composite Plating For Aluminum Substrates, Ben Charbit

Masters Theses

The effectiveness of producing a composite coating by suspending micron-sized particles in an electroless nickel bath while plating a 2024T4 aluminum alloy part was studied. The variation in the count of particles trapped in the nickel coating due to changes in the particle size, concentration of the particles in the bath, and the substrate surface texture was also studied. Particle sizes of 1 micron and 10 microns, concentrations of 15 gr/lt and 30 gr/lt, and polished and blasted textures were used. It was found that this technique is an effective way to produce composite coatings rendering a high number of …

Longitudinal Study Of Plasma And Erythrocyte Selenium Levels In Type I Diabetic Children During Development And Treatment Of Ketoacidosis, Pi-Hsia Fan

Chemistry & Biochemistry Theses & Dissertations

Most studies on the biological activity of selenium have focused on its role at the active site in the ubiquitous enzyme, glutathione peroxidase (GSH-Px) which catalyzes the removal of hydrogen peroxide and organic hydroperoxides (1). A connection between selenium deficiency and a wide range of diseases in animals and humans has been reviewed (2). Development of various forms of human cancer (3), failure of the immune system (4), as well as some cardiovascular diseases (5) have been reported or suspected to correlate with selenium deficiency. However, the physiological function of selenium in these different diseases is not fully understood, and …

Competitive Enzyme Immunoassay By Polyclonal Antibodies Against Organophosphorus Pesticides, Kuo-Lan Wen

Theses and Dissertations in Biomedical Sciences

Organophosphorus compounds (OPs) comprise one of the major classes of pesticides in use today because they are highly effective and less toxic. Because of their extensive use, there is a need for monitoring OPs in water and vegetables. Gas chromatography (GC) is the usual method for OPs screening, but it is time-consuming and has the high cost of instrumentation. The goal of this project was to find an easy method which was sensitive and had less instrumentation required to test OPs.

Microwells and microtubes were utilized as the solid-phase immobilization for the development of an enzyme immunoassay for OPs. A …

Using Animation In The Validation Of Simulation Models, Michael L. Carpenter

Theses and Dissertations

This study examined three aspects of animation (movement, color, and detail of icons) to determine which one (or ones) best communicated the operation of a simulation model. The procedure was done in the context of using animation to establish a model's face validity. Movement, color, and detail of icons were looked at individually and in combination. The ability to communicate was measured both subjectively and objectively. The subjective measures were a selection of best and worst animation types where best and worst referred to how well an animation communicated, and a pairwise comparison of the animation types which resulted in …

Enhancements To The Animated Tutor For Air Combat Simulation, David A. Legge

Theses and Dissertations

This study investigates the use of the Ada programming language in combat modeling. It takes an existing combat model, the Animated Tutor for Air Combat Simulation (ATACS), and re-writes it into Ada. The new model also includes enhancements to the original model. ATACS+, as it is now called, is used as a learning tool in combat modeling classes at the Air Force Institute of Technology. ATACS+ consists of a preprocessor and a model, complete with two and three-dimensional graphics and engagement status reports. Conclusion are made about Ada's suitability for combat modeling, some of the features of Ada which can …

The Integration Of Tanker Aircraft Into Aslar, John S. Stieven

Theses and Dissertations

The purpose of this study was to analyze the proposed addition of heavy KC-135 tanker aircraft to the United States Air Force Aircraft Surge Launch and Recovery (ASLAR) instrument approach system. The Air Force Communications Command, which oversees ASLAR operations, will use these results to determine if KC-135 aircraft should be permitted to fly ASLAR approaches. A SIMSCRIPT II.5 animated simulation model was developed to simulate the Runway 26 approach at Seymour Johnson Air Force Base under a variety of wind conditions. This model was expanded to show the feasibility of KC-135s flying ASLAR approaches and to determine proper controller …

Computer Aided Finite Element Stress Analysis Of A Three Dimension Mandibular Bone Model Using I-Deas Software, Yixiong Xu

Theses

A three dimensional model of half of the mandibular bone, with 487 tetrahedra elements and 1,047 nodes, is established and analyzed by means of I-DEAS software. The masseter muscle is assumed to be 15° deviation from y-axis, and the Umetani boundary conditions are allowed to be varied. A 337 lb force was applied along the midline of the mandible to simulate a trauma force caused by the auto accident. The maximum principal stress is 18,400 psi and the minimum principal stress is -1,340 psi. Depending on the experimental results of dispalcement and maximum principal stress, the conclusions are drawn: 1) …

Evaluation Of Truck Restrictions Using Simulation, Shaikh Mohamed Arif

Theses

Traffic congestion is a major problem in many central business districts. Many strategies have been proposed and implemented to solve or alleviate this problem. One of the most common strategies is to impose travel restrictions on the movement of trucks, without reviewing the economic consequences of goods movement restrictions on shippers, customers and on the overall business activity of the area.

This research examines the effect of various truck restrictive policies on the cost of urban goods movement, using the central business district of Manhattan as a case study. Computer simulation techniques are used to evaluate several scenarios under different …

The Thermal Model Of The Rat Under Hemorrhagic Shock Hypothermia With Microwave Intervention, Liu Zhe

Theses

A whole body thermal model simulating heat distribution and temperature regulation in rats during hemorrhagic shock and during post-shock microwave core rewarming period was developed. An electrical circuit was used to simulate the thermal system and a software named PSpice? was used to analyze the circuit. The temperature regulation as the result of the simulation is demonstrated to match the measured temperature histories of rats in hemorrhagic shock and the microwave rewarming experiment.

The blood pressure drop and cardiac output decrease were considered in the simulation and the so called "set point temperature" was investigated in the model. Linear decrease …

The Research, Design And Production Of Cortical Bone Pins And Screws For The Fixation Of Broken Bones In The Hand And Wrist, Ronald P. Holland

Opportunities for Undergraduate Research Experience Program (OURE)

Investigators at the University of Missouri at Rolla have entered into a joint venture with surgeons at Saint Louis University Hospital to develop a superior method of fixing broken bones of the human hand and wrist. This method involves the production of pins and screws from human cortical bone which will be used to fix broken bones for healing. The cortical bone fasteners will provide many advantages to the currently used metal fasteners. To date, prototype fasteners have been developed and are pending mechanical testing as a result of this undergraduate research project. Results of this project potentially include a …

Preliminary Outline For Preservation Of Tractor Test Building, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Outline of preliminary plan for the Preservation of the Tractor Test Building and early test equipment as monument to early days of the modern power farming industry.

Minutes Of Ag Tractor Test And Power Museum January 12th, 1993, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

No abstract provided.

The Honor Society Of Agriculture, Gamma Sigma Delta, Nebraska Chapter History, Diamond Jubilee 1918-1993, Charles H. Adams

Gamma Sigma Delta, Nebraska Chapter: Bylaws and Other Documents

GAMMA SIGMA DELTA is a faculty governed society that selects its members from junior and senior students, graduate students, faculty, and alumni for the promotion and recognition of high achievement. While Gamma Sigma Delta is an honor society of agriculture, it may elect members from related fields such as biology, botany, chemistry, economics, entomology, forestry, home economics, plant pathology, sociology, statistics, veterinary medicine, or zoology when the work of the individuals is related to agriculture. Officers, committee chairpersons, and others leading the chapter are faculty or alumni.

EARLY INTERNATIONAL HISTORY

GAMMA SIGMA DELTA INTERNATIONAL OFFICERS FROM THE NEBRASKA CHAPTER

THE …

Heating Of Calcium Phosphate Crystals: Morphological Consequences And Biological Implications, W. Bohne, J. A. Pouezat, L. Peru, G. Daculsi

Cells and Materials

Sintering hydroxyapatite (HA) and ß-tricalcium phosphate (ß-TCP) affects the chemical composition, the crystallinity, and the morphological features as demonstrated by means of X-ray diffraction (XRD) , infrared spectroscopy (IR), and scanning electron microscopy (SEM). When heated to 1230°C, 16.7% of HA had decomposed to ß-TCP. SEM investigations showed homogeneous, sharp angular polyhedric blocks of 30 to 50 µm with rare surface pores. On heating at 1230°C, ß-TCP had entirely transformed to a-TCP. During sintering, the size of the powder grains increased and progressive bridging between the grains was observed. At 1230°C, a network within round-shaped polyhedric blocks of 50 to …

Ultrastructural, Cytochemical, And Immunocytochemical Studies On Bone And Its Interfaces, M. D. Mckee, A. Nanci

Cells and Materials

Bone cells possess the ability to synthesize, secrete and direct the assembly and maintenance of extracellular matrix to form a functionally rigid and/or weight-bearing mineralized tissue complex, the skeleton. The skeleton not only supports and protects the organs and tissues of the body, but also acts as a mineral ion reservoir for maintaining systemic calcium balance (calcium homeostasis). The remarkable biological precision necessary for the formation, turnover and constant adaptation of bone to external mechanical forces is a dynamic process requiring a coordinated cellular effort relying on a variety of cell-cell and cell-matrix/mineral interactions. Indeed, cell-matrix interfaces found in a …

Multinucleated Giant Cells-Hydroxyapatite Interactions: A Time-Related Quantitative Study In A Rat Skull Defect, J. M. Dersot, A. Llorens, J. L. Saffar

Cells and Materials

The implantation of calcium phosphate ceramics in the bone environment elicits the differentiation of multinucleated giant cells (MNGCs). MNGC interactions with both crushed and standard hydroxyapatite (HA, Bioapatite ®) particles (cHA and sHA) were studied in rat skull defects. Light microscopy (LM) of undemineralized material after 21 and 42 days of implantation showed that the number of particles in the defect significantly decreased (about SO%) with the two HA forms. Concomitantly, average cHA particle size increased significantly due to the elimination of the smallest particles by the MNGCs. The number of MNGCs per mm2 of defect decreased significantly between 21 …

A Comparative Study Of The Interactions Of Two Calcium Phosphates, Peo/Pbt Copolymer (Polyactive) And A Silicone Rubber With Bone And Fibrous Tissue, C. A. Van Blitterswijk, J. R. De Wijn, H. Leenders, J. V.D. Brink, S. C. Hesseling, D. Bakker

Cells and Materials

In this study, hydroxyapatite, tetracalcium phosphate, HPEO/PBT 55145 copolymer, PEO/PBT 55!45 copolymer (Polyactive) and silicone rubber were implanted as dense blocks, subcutaneously and. into the tibia of rats. Biocompatibility and degradation were investigated but most attention was directed to .the bone/biomaterial interactions. None of the materials showed any significant adverse tissue reactions. With exception of the silicone rubber, all materials sho~ed bone bonding phenomena based on both morphological and mechanical evaluations. (H)PEO/PBT 55145 copolymer is the first polymer reported to be bonded by bone and thus widens the spectrum of bone bonding materials with a low modulus, degradable, elastomer in …

Lysine Effect On Ruthenium Red And Alcian Blue Preservation And Staining Of The Staphylococcal Glycocalyx, Theresa A. Fassel, James R. Sanger, Charles E. Edmiston

Cells and Materials

The effect of lysine on ruthenium red (RR) and alcian blue (AB) preservation arid/or staining for transmission electron microscopy of glycocalyces was evaluated for three species of the gram-positive, coagulase-negative staphylococci. A RR and an AB procedure were compared with and without lysine included in the glutaraldehyde prefixation. Minimal or no glycocalyx was preserved or stained by glutaraldehyde fixation only. For all species, the inclusion of lysine increased visualization of fibrous material. RR treatment without lysine, results in sparse or limited fibrous material or artifactual condensations which contrasts with enhanced fibrous material seen when lysine is included with RR. The …

Are Long Term Cryopreservation And Patency Of Vein Allograft Truly Achievable?, G. Pasquinelli, G. L. Faggioli, P. Preda, M. Vici, G. N. Martinelli, R. Giardino, M. D'Addato, J. J. Ricotta

Cells and Materials

Despite extensive experimental work, neither the effect of long term cryopreservation on vein graft architecture nor the failure of alloveins due to graft rejection have yet been investigated. Herein, we investigated ultrastructurally: a) the integrity of rabbit jugular veins following 1, 2 and 3 months of cryopreservation; b) the outcome of the three-month cryopreserved vein auto- and allografts after 1 month of implantation in the rabbit carotid artery; and c) the immunologic response to cryopreserved vein allografts with and without seeded autologous endothelium. Prior to implantation, the cryopreserved rabbit veins were well-maintained except for endothelial cell damage. Following implantation, the …

Influence Of Crystal Structure On The Establishment Of The Bone-Calcium Phosphate Interface In Vitro, J. D. De Bruijn, C. P. A. T. Klein, K. De Groot, C. A. Van Blitterswijk

Cells and Materials

An in vitro rat bone marrow cell system was used to examine the interfacial ultrastructure established between various calcium phosphates and mineralized tissue. The investigated calcium phosphates comprised hydroxyapatite (HA), fluorapatite (FA), tricalcium phosphate (TCP), tetracalcium phosphate (TECP) and magnesium whitlockite (MWL). Both scanning and transmission electron microscopy were used to examine the elaborated interface. The time in which a mineralized extracellular matrix was formed on the various materials differed from 2 weeks on HA, TCP and TECP, to 8 weeks on FA. It was only occasionally observed in some areas on MWL, which might have been due to aluminum …

Degradation Of Polymeric Biomaterials, Shalaby W. Shalaby, Russell A. Johnson, Meng Deng

Cells and Materials

Environmental and processing factors affecting the biostability of medical devices made from traditionally "stable" polymers, such as isotactic polypropylene (PP) and ultrahigh molecular weight polyethylene (UHMW-PE) , were analyzed and their undesirable degradation was related to performance of typical medical devices. Among the critical phenomena determining the biological performance of UHMW-PE and PP devices are oxidation during melt-processing and the propensity of the polymer chains to radiolyse and radio-oxidize. Polyesters and their biomedical devices , which can be designed to degrade predictably, are addressed with some focus on the less obvious determinants of performance.

Outline For Tractor Testing Farm Machinery Museum, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

General statement for developing a museum, justification, current groups, building considerations, and tractor test museum committee

Osteoclastic Resorption Of Calcium Phosphate Ceramic Thin Films, J. E. Davies, G. Shapiro, B. F. Lowenberg

Cells and Materials

Sub-micron calcium phosphate ceramic thin films were formed by vertically dipping transparent quartz plates in a particulate sol-gel suspension. Primary adult rat bone marrow cell populations were cultured on the ceramic thin films in conditions known to allow the differentiation of cells of the osteoclast lineage. Monitoring the cultures for periods of 11 to 28 days revealed the creation of resorption lacunae in the thin films by multinucleate cells. Some cultures were heated at 42 °C overnight to remove adherent cells; using bright field light microscopy (LM), after staining with silver nitrate, the degree of resorption could be easily assessed. …

Preferential Adhesion Of Urethral Bacteria From A Mixed Population To A Urinary Catheter, Gregor Reid, Christina Tieszer

Cells and Materials

The ability of uropathogens to adhere to catheters and subsequently colonize the urinary mucosa leads to urinary tract infections which afflict a large patient population. In vitro studies were carried out whereby Escherichia coli Hu734 (water contact angle 12 °) and Enterococcus faecalis (19°) were found to be highly adhesive to silicone latex urinary catheters. The addition of one of four Lactobacillus sp., with water contact angles ranging from 19-105 °, to the suspending fluid caused a 60-86% reduction in pathogen adhesion with a significant effect against E. coli, the organism most commonly found to infect the urinary tract. …

Morphological Characterization Of Maltodextrin Derivatives Using Scanning Electron Microscopy, K. K. Singh, D. J. Robison, Y. V. Pathak

Cells and Materials

This paper deals with the study of the significance of the morphological characteristics of some maltodextrin derivatives in the preparation of tablet dosage forms. Six maltodextrin derivatives, M-040, 100, 150, 180, 500, and 700, with varying dextrose equivalent (DE) values and varying degrees of agglomeration were studied for their suitability in the preparation of the tablets based on the morphological characteristics observed by scanning electron microscopy. A comparison of micromeritic properties, moisture absorption, and morphological characteristics of various maltodextrin derivatives is reported.

Immunocytochemical And Lectin-Gold Characterization Of The Interface Between Alveolar Bone And Implanted Hydroxyapatite In The Rat, H. Kawaguchi, M. D. Mckee, H. Okamoto, A. Nanci

Cells and Materials

The tissue response to implanted hydroxyapatite (HAP) in rat alveolar bone was investigated using morphological and cytochemical approaches. High-resolution immunogold labeling was used to examine the distribution of two non-collagenous bone proteins, osteopontin and osteocalcin, and two plasma proteins, a2HSglycoprotein (fetuin) and albumin. Glycoconjugates were characterized by lectin-gold cytochemistry using Ricinus communis I agglutinin and Wheat germ agglutinin. Transmission electron microscopy demonstrated the presence of an electron-dense, lamina limitans-like layer at the HAP particle-bone interface and organic material within the micropores of the particles. Mineral was observed in relation to both these sites. The HAP particle-bone interface was strongly …

Organic Extracellular Matrix Components At The Bone Cell/Substratum Interface, X. Shen, E. Roberts, S. A. F. Peel, J. E. Davies

Cells and Materials

We have recently shown that differentiating bone cells are capable of elaborating, in vitro, a calcified matrix at the interface with several non-biological substrata which is similar to cement lines found in remodelling bone tissue. From previous morphological observations, this matrix appeared free of assembled collagen fibres which indicated that osteogenic cells produce an initial mineralized matrix before overt collagen fibre production. In the work reported herein, we used six antibodies to extracellular matrix components and two conjugates of secondary antibody, fluorescein and colloidal gold, to initiate a preliminary characterization of the organic components at the bone cell substratum …

The Effect Of Peo Ratio On Degradation, Calcification And Bone Bonding Of Peo/Pbt Copolymer (Polyactive), C. A. Van Blitterswijk, J. V.D. Brink, H. Leenders, D. Baaker

Cells and Materials

In this study, we evaluated the effect of PEO/ PBT proportion on the behavior of a range of PEO/ PBT segmented copolymers (Polyactive) during subcutaneous and intrabony implantation in the rat. It was demonstrated that varying the PEO proportion affected degradation, calcification and bone-bonding. The PEO/PBT 70/30 and 60/40 showed extensive degradation after 1 year, PEO/PBT 55145 an intermediate degradation, and the 40/60 and 30170 copolymers showed little and hardly any degradation respectively. PEO content also affected the degree of calcification . PEO/PBT 70/30 showed extensive and early calcification whereas almost no calcification was seen with PEO/PBT 30170. Since calcified …

Characterization Of Bovine Osteoclasts On An Ionomeric Cement In Vitro, D. H. Szulczewski, U. Meyer, K. Moller, U. Stratmann, S. B. Doty, D. B. Jones

Cells and Materials

Primary bovine osteoclasts were obtained by an outgrowth method from bovine periosteum and cultured for 7 days on an ionomeric cement for biomaterial testing. Osteoclasts cultured on slices of bovine bone and on glass microscope cover-slides served as a control. The cells were characterised as osteoclasts by a number of tests. Osteoclasts showed positive staining for tartrate resistant acid phosphatase and reactivity with the antibodies 13C2 and 23C6, which react with the alphachain of the vitronectin receptor. Addition of salmon calcitonin to the culture medium led to sudden cessation of lamellipodial activity. The cells resorbed bone by making pits. In …

Pulpal Response To Calcium Phosphate Materials. In Vivo Study Of Calcium Phosphate Materials In Endodontics, A. H. Jean, J. A. Pouezat, G. Daculsi

Cells and Materials

The aim of this study was to determine if calcium phosphate (CaP) materials could be used to substitute for calcium hydroxide (CH) as a pulp capping agent. Especially prepared and characterized CaP materials with CH as the reference or control material were used for pulpcapping teeth of pigs, rats, and dogs. The CaP materials included: DCPD (dicalcium phosphate dihydrate), OCP (octacalcium phosphate), ß-TCP ({3-tricalcium phosphate), BCP (biphasic calcium phosphate mixture of 50150 HA and ß-TCP), and HA (hydroxyapatite) which were used in particle sizes of < 5 μm or < 150 μm. The animals were sacrificed after 21 days to …