Engineering Commons^™

Adhesion Of Staphylococci To Breast Prosthesis Biomaterials: An Electron Microscopic Evaluation, T. A. Fassel, J. E. Van Over, C. C. Hauser, C. E. Edmiston, J. R. Sanger

Cells and Materials

Gram-positive coagulase-negative staphylococci have been implicated in breast prosthesis infection. Staphylococcus au re us, Staphylococcus epidermidis, and Staphylococcus hominis strains were examined for adhesion and proliferation morphology to polyurethane foam and smooth silicone rubber prosthetic biomaterials. Ruthenium red, alcian blue and ruthenium red-lysine in en bloc procedures were applied to optimally visualize the polysaccharide slime. Ruthenium red processing resulted in observation of additional outer material close to the cell wall, more than seen in the absence of cationic reagent. Alcian blue preserved fibrous or netlike strands or meshworks of material. Ruthenium red-lysine preserved considerable amounts of slime covering the cocci …

A Comparative Study Of Bovine Pericardium Mineralization: A Basic And Practical Approach, Branko B. Tomazic, Chakwan Siew, Walter E. Brown

Cells and Materials

The biomineralization of bovine pericardium (BP) heart valve bioprostheses was investigated by simulation of the process under in vitro and in vivo conditions. The nature and composition of calcific deposits that formed in human heart valve bioprostheses were compared with the mineral formed on BP discs immersed in a calcifying medium or subcutaneously implanted into Sprague-Dawley rats. The early stage of experimental biomineralization in vitro took place on the surface only, while in vivo deposition appeared to be intrinsic, as documented by histological cross sections. The chemical composition of the initial mineral phase formed under in vitro conditions had a …

The Articular Cartilage Of The Rabbit Knee: A Scanning Electron Microscopy Study, Daniel Levanon, Haim Stein

Cells and Materials

The surface morphology of eight sectors in the rabbit knee articular cartilage was studied using scanning electron microscopy. Cartilage surfaces showed wide variation in the shape, dimensions , and density of gaps and acellular processes. Patellas and load-bearing condyles revealed a relatively higher density of processes than did load-free condyles. Surface processes and gaps were abundant. They might represent a condensation product(s) of hyaluronic acid/protein complex that accrues during cycles of loading/weight bearing.

Preservation Of The Cell-Biomaterial Interface At The Ultrastructural Level, J. M. Schakenraad, J. A. Oosterbaan, E. H. Blaauw

Cells and Materials

Studying the tissue-biomaterial interface at the ultrastructural level is not without problems. Dissolution of the biomaterial in one of the dehydration or embedding media causes holes and shatter during sectioning or dislodgement of the biomaterial. The fine tuning of the hardness of both biomaterial and embedding medium, as well as the introduction of butyl-2,3- epoxypropylether as an intermediate between the dehydration series and the Epon resin , improving the impregnation , will solve many of the problems mentioned. With this improved technique good results were obtained with materials ranging from teflon, poly(Lactic acid) and polyurethanes to tissue culture polystyrene. No …

Adhesion And Spreading Of Human Fibroblasts On Superhydrophobic Fep-Teflon, H. J. Busscher, I. Stokroos, J. G. Golverdingen, J. M. Shakenraad

Cells and Materials

Adhesion and spreading of human fibroblasts was studied on hydrophobized and hydrophilized FEPTeflon, and compared with adhesion and spreading on untreated FEP-Teflon and Tissue culture polystyrene (TCPS). Superhydrophobic FEP-Teflon was prepared by ion etching followed by oxygen glow-discharge. Hydrophilic PEP-Teflon was prepared by ion etching only. Water contact angles of the modified surfaces were 140- 1500 and 5-10° for the hydrophobic and the hydrophilic variant, respectively. (Untreated FEP-Teflon: 109°). Spreading of human skin fibroblasts significantly increased on hydrophilic FEP-Teflon (257 μm2 per cell), whereas a significant decrease was observed on superhydrophobic FEP-Teflon (158 μm2 per cell), as compared to untreated …

Tailwater Recovery Demonstration Program Study, Doug Welch, Tim O'Halloran, Stuart Styles

BioResource and Agricultural Engineering

No abstract provided.

Surface Modification Of Polymers To Permit Endothelial Cell Growth, C. James Kirkpatrick, Detlef Mueller-Schulte, Marc Roye, Guenter Hollweg, Claudia Gossen, Horst Richter, Christian Mittermayer

Cells and Materials

The interaction between endothelial cells (EC) and polymers has become relevant to medicine as a result of attempts to improve the biocompatibility of vascular prostheses. In man, endothelialization is minimal, so that vascular surgeons have attempted to pre-seed vascular grafts with autologous EC. The poor results of EC seeding of commonly used materials for vascular grafts, such as expanded polytetrafluoroethylene (ePTFE) or woven polyester (Dacron) has led to attempts to modify the surface of these and other polymers. Three principal modification techniques have been employed : 1. adsorption of bioactive molecules from applied solutions. Examples are fibronectin, collagen types I …

Dusts Produced During Cutting Of Modern Splinting Bandages, R. Wytch, D. W. Gregory, R. Clayton, D. Wardlaw

Cells and Materials

Previous work carried out by the authors (Wytch et al ., 1988a) has shown that airborne dust generated during removal of orthopaedic casts with a power saw could represent a respiratory hazard. Further work has been carried out on all types of splinting bandage currently available in the United Kingdom to assess the potential dust hazard when sawing these materials. It has been shown that although plaster of Paris bandage produces significant concentrations of airborne dust, most of the polyurethane-impregnated fabric bandages generate extremely low levels of dust and in the case of the non-glass fabrics, the level is insignificant. …

Instability And Collapse Behavior Of A Seismic Structure, Franklin Y. Cheng, Jeng Fuh Ger

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The collapse behavior of a 22-story steel building during the September 19, 1985, Mexico earthquake is investigated by studying hysteretic behavior, ductility factors of individual structural components, and overall instability of the building. The hysteresis models for truss-type girders, bracing members, and box columns to be used in the inelastic analysis of this building are developed. A series of inelastic analyses have been performed for the building by using the multicomponent seismic input of actual Mexico City earthquake records. It was found that the structural response exceeds the original design ductility of this building because most girders in the building …

Test 1642: Ford 3230 (8x2) Diesel 8-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

The Calendar - January 1991, Nova University

The Calendar

No abstract provided.

The Calendar - February 1991, Nova University

The Calendar

No abstract provided.

Subsidence Resulting From Multiple-Seam Longwall Mining In The Western United States - A Characterization Study, United States Department Of The Interior, Bureau Of Mines

Mines and Mineral Resources

This report details the investigation of multiple-seam longwall subsidence conducted by the U.S. Bureau of Mines from 1978 to 1989. A field investigation monitored ground surface movements over four upper-seam longwall panels and six lower-seam panels. The characteristics of the subsidence occurring as a result of mining these panels are examined; in particular, the angle of draw, subsidence development, total magnitude and areal extent, and critical width are evaluated and discussed. Comparisons are also made between the characteristics of multiple-seam longwall subsidence and single-seam longwall subsidence that occurred at the same site.

The Development Of A Concrete Interlocking Partition Walling Unit, Haldane L. Johnson

Graduate Student Work

This research aimed to develop a better method of erecting internal partition walls for the Jamaican housing industry. An interlocking concrete block wall unit was considered appropriate because it used local materials and required semi-skilled labor to erect.

A timber mold was made to manually produce the 4 x 4 x 8 inch block. The concrete mix used had a cement to aggregate ratio of 1:7.5 and a sand to gravel ratio of 1:2 and a water cement ratio of 0.753. The average compressive strength of the block determined after three days was 351.56 psi. This translates into an expected …

Content And Strategies For Teaching Computer-Aided Drafting, Kurt Henry Becker

Engineering Education Faculty Publications

No abstract provided.

Testing The Economic Order Quantity Model On Maintenance Inventory, Teresa J. K. Hall

Graduate Student Work

This pilot study seeks to determine the effect a non-traditional method of inventory control may have on industrial maintenance repair parts inventory. The application of mathematical models designed for production inventory to Maintenance, Repair and Operating (MRO) inventory has not been widely researched, although theorists and practitioners feel there is potential for some models. The Economic Order Quantity (EOQ) theory has proven to be effective in production inventory circles. This pilot study examined the effectiveness of the EOQ in terms of holding cost of the inventory and number of out-of-stock conditions versus the Weighted Moving Average method currently in use …

State Of Maine Rail Transportation Plan, Maine Department Of Transportation

Maine Collection

State of Maine Rail Transportation Plan

Revised Update - Prepared by the Department of Transportation, Bureau of Transportation Services, Augusta, Maine, 1991.

"The revised update of the State of Maine Rail Transportation Plan has been developed by the Rail Transportation Division. Bureau of Transportation Services of the Maine Department of Transportation pursuant to rules and regulations promulgated in Part 266 of Title 49 of the Code of Federal Regulation."

Osha Compliance By Small And Medium Business, Bill W. Trammell

Graduate Student Work

It is hypothesized that even though governmental rules, regulations, and policies along with ethical. social, and moral dictates within our communities now require, even demand, that businesses and industry provide their employees a healthful and safe working environment the opposite is often the case. There is a substantial number of employers, within the small to medium sized industrial manufacturers, whose chief executive officers: (1) fail to implement a safety program within their organization; (2) fail to provide more than token attention to employee safety and the intent of the OSHA regulations; (3) have no sincerity or intention to complying with …

Analytical And Experimental Investigation On Vibration Control Of Piezoelectric Structures, M. J. Tzeng, W-Z Ben Wu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Active vibration control of smart structural materials (beam and plate) has been achieved by using distributed piezoelectric actuators. Numerical simulation and experimental testing have been conducted to investigate vibration suppression of the advanced structures. Results from simulation and testing are in satisfactory agreement.

A Simple Method For Ultrastructural Evaluation Of Fragile Collagenous Biomaterials, Arthur J. Wasserman, Yasushi P. Kato, Frederick H. Silver

Cells and Materials

No abstract provided.

Peripheral Nerve Regeneration Within Tubular Prosthesis: Effects Of Laminin And Collagen Matrices On Cellular Ingrowth, Ivar J. Kljavin, Roger D. Madison

Cells and Materials

Bridging a severed peripheral nerve with a tubular conduit, "entubulation repair" , allows manipulation of the microenvironment encountered by regenerating axons. In the present study, we placed the ends of severed mouse sciatic nerves into nonpermeable Tygon tubes to bridge a 4 mm nerve gap. The tube lumen was filled with either a collagen or laminin matrix. The matrices formed a stable 3-D structure connecting both proximal and distal stumps, and provided a scaffolding for the regenerating axons and their supporting cells. We examined with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and light microscopy, the initial events of …

Ultrastructural Study Of Bone Formation On Synthetic Hydroxyapatite In Osteoblast Cultures, J. M. Sautier, J. R. Nefussi, N. Forest

Cells and Materials

Collagenase isolated rat calvaria cells forming a mineralized matrix in vitro were cultured in the presence of synthetic hydroxyapatite. Interactions between bone cells and hydroxyapatite biomaterial were followed by transmission electron microscopy. The appearance of a granular, collagen free, electron-dense layer at the periphery of the material was noted initially. Progressively, an amorphous, granular material formed and extended between the hydroxyapatite aggregates. Osteoblastic cells then synthesized an osteoid matrix which mineralized on the first formed granular collagen free layer, following a classical pattern of calcification . Demineralization of ultrathin sections confirmed the presence of this interface between the material and …

Interactions Of Bacteria And Amoebae With Ocular Biomaterials, Thomas John

Cells and Materials

The use of biomaterials in periocular and intraocular sites has resulted in some ocular inflammations and infections which can result in vision-threatening ocular disease. This review addresses bacterial interactions with, and adherence to ocular biomaterials such as soft contact lenses, surgical suture materials, and intraocular lenses. In addition, adherence of Acanthamoeba to soft contact lenses is described, and the role of these lenses in the development of Acanthamoeba keratitis is discussed.

Evaluation Of The Images Of Specular Microscopy Of The Cells On Implanted Intraocular Lenses In Vivo, Kiyoshi Okada, Keiko Takahashi, Hiroaki Sagawa, Kuniomi Abe

Cells and Materials

Specular microscopy , an optical method to study the anterior segment of the eye, was applied to observe the cells on implanted intraocular lenses in vivo. The images from specular microscopy were evaluated by comparing the morphology of the same cells on intraocular lenses implanted in rabbit eyes by specular microscopy , light microscopy and scanning electron microscopy (SEM). The time lapse study in living human eyes and the optical evaluation of jts interference images were performed to elucidate its image formation.

The same giant cells, as observed in vivo by specular microscopy, proved to be multinucleated cells. It …

Stereoscopic Analysis Of Trabecular Bone Orientation In Proximal Human Tibias, K. N. Bachus, M. K. Harman, R. D. Bloebaum

Cells and Materials

The three-dimensional orientation of trabeculae is a key factor in determining the load carrying capabilities of cancellous bone. Previous biomechanical studies have shown that proximal tibias resected parallel to the articulating surface are stronger and stiffer than the contralateral tibias resected perpendicular to the long axis of the bone. However, morphologic evidence was not provided to help explain the mechanical differences.

To determine the orientation of the trabeculae in the medial condyle for both parallel cut and perpendicular cut specimens, a scanning electron microscope and stereoscopic techniques were used. Data showed that tibias cut parallel to the articular surface had …

Investigation Of Channel Degradation 1991 Update Missouri River Gavins Point Dam To Platte River Confluence

United States Army Corps of Engineers, Omaha District

1. PURPOSE. This report is the fifth in a series of updates to Volume IV, supporting Technical Report, Missouri River Degradation. Volume IV is a part of the August 1981 Review Report of the water and Related Land Resources Management study for Metropolitan Sioux city and Missouri River Iowa, Nebraska, and South Dakota. This report, along with future updates, will provide the information necessary for proper management of the Missouri River in reference to degradation.

2. SCOPE. This report incorporates water surface profile and hydrographic survey data from the 1989 and 1990 water years for the purpose of updating the …

Transformation Of 1-Aminonapththalene At The Surface Of Smectite Clays, Calvin C. Ainsworth, Bruce D. Mcveety, Steven C. Smith, John M. Zachara

United States Department of Energy: Publications

One-aminonaphthalene is sorbed onto the Na-saturated smectite clays, montmorillonite and hectorite, by cation exchange. In the presence of Fe³⁺ either in the clay structure or on the clay surface, sorption is followed by the formation of a blue-colored complex, with the continuous disappearance of aminonaphthalene from solution and the clay surface. The rate of aminonaphthalene disappearance decreases as pH increases. With time, four major products that appear to be structural isomers of N(4- aminonaphthyl)-1-naphthylamine are produced. A simplified model of this transformation is suggested to be the oxidation by Fe³⁺ of sorbed aminonaphthalene forming a radical cation-clay complex. …

Automating Tolerance Synthesis: A Framework And Tools, Stephen C.-Y. Lu, Robert G. Wilhelm

Department of Mechanical and Materials Engineering: Faculty Publications

This paper describes CASCADE-T—a new approach to tolerance synthesis that uses a complete representation of the conditional tolerance relations that exist between features of a part under design. Conditional tolerances are automatically determined from functional requirements and shape information. Tolerance primitives based on the virtual boundary requirements approach to tolerance representation are composed to form more complex tolerance relationships. Artificial intelligence techniques, including a constraint network, frame-based system, and dependency tracking are used to support flexible and detailed computation for tolerance analysis and synthesis.

Forming Fine Particles, Dennis R. Alexander

Department of Electrical and Computer Engineering: Faculty Publications

To alter feedstock material, the material is exposed to laser radiation applied at a selected angle of incidence, intensity and wavelength related to the refractive index of the feedstock material. Fine uniform particles may be formed through vapor explosion and/or plasma formation and used by this method to coat surfaces, such as with paint or adhesive or to suply uniform small particles to a heat engine. Moreover, moving materials such as a column of liquid may be subjected to high internal pressure and temperature for creating physical and chemical changes.

What To Look For And Why When Buying A Telecommunications Switch

ACUTA: Other Publications

There are three characteristics of institutions of higher education that have a strong

impact on telecommunications:

. Campus Environment

. Multiple Service Populations

. Limited Budgets

Each characteristic translates into requirements for an effective telecommunication

system.

To Serve the Campus Environment

A campus is usually the first image associated with the word "college" or "university." Typically, institutions of higher education are housed in several buildings which may be fairly close together, or spread over some distance, perhaps reaching across a city or even a state.

To serve the campus user, a system must provide feature transparency, regardless of location. Small …