Engineering Commons^™

Preliminary In Vivo Studies Of A New Injectable Bone Substitute, F. Millot, G. Grimandi, P. Weiss, G. Daculsi

Cells and Materials

Calcium-phosphate materials have been increasingly employed in orthopedic and dental applications in recent years and are now being developed for use in noninvasive surgery or as carriers for drug delivery systems. We developed an injectable bone substitute (IBS) for percutaneous orthopedic surgery which uses a biphasic calcium-phosphate (BCP) mixture composed of hydroxyapatite (60%) and ß-tricalcium phosphate (40%), together with a polymer (hydroxy-propyl-methyl-cellulose, HPMC) as a carrier. The best BCP/polymer ratio was determined to achieve the highest mineral phase in the composite and provide the rheological properties required for injectable material.

The in vivo biocompatibility and biofunctionality of IBS were …

Mechanical Properties Of Dendritic Pd-Cu-Ga Dental Alloys, Efstratios Papazoglou, Qiang Wu, William A. Brantley, John C. Mitchell, Glyn Meyrick

Cells and Materials

Three Pd-Cu-Ga dental alloys with very similar nominal compositions and dendritic as-cast microstructures were selected for study: Option (Ney Dental) and Spartan (Williams/lvoclar) contain a small amount of boron, while Spartan Plus (Williams/Ivoclar) is boron-free. Bars of each alloy were tested in tension for the as-cast and simulated porcelain-firing conditions, and values of mechanical properties were measured. Fracture surfaces and microstructures of axially sectioned and etched fracture specimens were observed with the scanning electron microscope (SEM). Except for the elastic modulus, significant differences were typically found in alloy properties. Heat treatment eliminated the dendritic microstructure, decreased strength and increased ductility. …

X-Ray Diffraction And Scanning Electron Microscopy Analyses Of A Gallium-Based Dental Restorative Alloy, Randa E. Shaker, William A. Brantley, Qiang Wu, John C. Mitchell

Cells and Materials

Specimens of a gallium-based dental alloy were prepared with different condensation techniques, with and without the removal of a surface layer, and after aging for 2 hours at 50°, 100° and 150°C. X-ray diffraction at times ranging from 10 minutes to 1 day showed the development of the four matrix phases (ß-Sn, CuGa₂, Ga₂₈Ag₇₂, and In₄Ag₉) during the setting reaction. Scanning electron microscope (SEM) examination of specimens loaded to failure revealed brittle fracture, with greater porosity for hand-condensed specimens, and provided insight into crack propagation processes. Aging increased …

Formation Of Cement Lines, But Not Laminae Limitantes, Requires Contact Of Differentiating Osteogenic Cells To Solid Surfaces, M. M. Hosseini, A. Shiga, J. E. Davies

Cells and Materials

We designed in vitro experiments to address the hypothesis that cement lines and laminae limitantes are structurally distinct as a result of cell contact, or absence of cell contact, during their elaboration. We subcultured young adult primary rat bone marrow cells in well inserts with polycarbonate membranes of 0.45 µm pore size, which allowed protein but not cell passage. The cells, extracellular matrix, lower side of the membrane and the surface of the polystyrene culture well were examined by scanning and transmission electron microscopy. The cells elaborated a bone-like matrix on top of the membrane. In such cultures the …

Effects Of Casting Conditions And Annealing On Microstructures And Vickers Hardness Of Dendritic Pd-Cu-Ga Dental Alloys, William A. Brantley, Qiang Wu, Zhuo Cai, Stanley G. Vermilyea, John C. Mitchell, Michael C. Comerford

Cells and Materials

Three Pd-Cu-Ga alloys with as-cast dendritic microstructures and very similar compositions, two containing less than 1 wt% boron and the third boron-free, were cast with normal bench-cooling or rapid-quenching into water. Quenched specimens were also heat treated at temperatures of 1000°, 1200°, 1500° and 1800°F that span the firing cycles for dental porcelain. Similar values of Vickers hardness were observed for all three alloys, suggesting little effect from boron on yield strength. The hardness was relatively insensitive to the experimental conditions, except for heat treatment at 1500° and 1800°F where significant softening occurred with transformation of the microstructure to Pd …

Behavior Of Melanoma Cells In Cell And Organ Cultures: Use Of Biomaterials To Activate Cells, J. L. Duval, N. Faucheux, R. Warocquier-Clérout, M. D. Nagel

Cells and Materials

It is well known that cell behaviors such as adhesion, proliferation and various synthesis are initiated from transmembrane signals. This study uses biomaterials as primary messengers of the cell activation pathways, and we have analyzed the effects of two biomaterials on highly metastatic tumor cells. B16F10 melanoma cells formed heterogeneous populations whose size varied with cell differentiation. In long-term organ cultures grown comparatively on AN 69 and Cuprophan (a biomembrane known to activate cells), we found that Cuprophan increased both adhesion and proliferation of small melanin-rich cells which represented differentiated melanocyte&. In dissociated cell cultures, the rate of early cell …

In Vitro Comparative Biocompatibility Testing Of Carbofilm Coated And Uncoated Polyetherimide For Cardiovascular Application, M. Bosetti, S. Mazzarelli, L. Nicolais, L. Ambrosio, M. Cannas

Cells and Materials

When blood contacts the surface of a material, several processes take place including the activation of coagulation and immune systems. The aim of this work is to study in vitro the biological reactions seen from the point of view of hemocompatibility and cytocompatibility of a new polymer suggested as an artificial surface for cardiovascular applications: Carbofilm® coated polyetherimide (C®PEI) in comparison to polyetherimide (PEI), the uncoated form. PEI and C®PEI showed no signs of acute cytotoxicity although following long term incubation with PEI cytotoxicity was somewhat increased; both materials supported good endothelial cell adhesion with a higher level of cell …

Quantifying The Surface Geometry Of Titanium Implant Material By Different Methods Of Analysis, Clara Pimienta, Rashad Tawashi

Cells and Materials

Biomaterial implant manufacturers have used rough surfaces to ensure better biocompatibility, less rejection and better adaptation of implants in the body. Proper characterization of biological interactions and biocompatibility of biomaterials requires a thorough understanding of surface complexity. Surface roughness has often been shown to be important in influencing biological reactions with the surface. Previous communications from our laboratory have described a dynamic active vision system (MVS camera) capable of measuring three-dimensional coordinates of titanium implant material surfaces. Fractal analysis, due to its straightforward relationship to texture, is used to characterize the degree of irregularity of a surface and is expressed …

Image Analysis And The Effect Of Molecular Orientation On Degrading Lactide Polymer Films, K. J. L. Burg, M. Laberge, D. L. Powers, S. W. Shalaby

Cells and Materials

Absorbable polylactide films were studied in order to observe the effect of orientation on the resulting hydrolytic degradation pattern. Two types of polylactide films with two levels of molecular orientation were studied, during a nine month exposure to a phosphate buffered solution at 37°C. The films were sectioned and quantified as to void area, birefringence area, and intensity of birefringence using a microscope and an image analysis software package. The results, obtained using an analysis of variance, showed that the orientation played a significant role in the degradation pattern of the polylactide films, either decreasing or causing no change in …

Biomimetic Habitats For Cells: Ordered Matrix Deposition And Differentiation In Gingival Fibroblasts Cultured On Hydroxyapatite Coated With A Collagen Analogue, Rajendra S. Bhatnagar, Jing Jing Qian, Anna Wedrychowska, Eric Dixon, Nancy Smith

Cells and Materials

In tissues, cells attach and migrate on collagen. Interaction with collagen modulates cell proliferation and differentiation. We propose that similar environments may be constructed by immobilizing collagen-derived cell-binding peptides in a three-dimensional (3-D) template. We identified a cell binding domain of type I collagen and showed that a 15-residue synthetic analogue (P-15) binds cells with high affinity. In the present study, we compared the behavior of human gingival fibroblasts (HGF) in culture on hydroxyapatite (HA) and on HA-P-15. HGF cultured on HA formed sparse monolayers with little order and deposited a scant matrix. HGF on HA-P-15 formed highly oriented 3-D …

Transition Criteria - From A Pit To A Crack, Tarun Goswami, David W. Hoeppner

Biomedical, Industrial & Human Factors Engineering Faculty Publications

A brief review of pitting, which is a localized corrosion process resulting from pitting and fatigue interaction has been conducted in this paper. The transition of a pit to a crack is a very important phenomenon occurring under PCF conditions. Various theories for transition of a pit to a crack were examined within the limits of present understanding and limitations of the models. The transition of a pit to a crack was also discussed for a variety of pit shapes utilizing the pit aspect ratios, defect size and linear elastic fracture mechanics, crack tip characterizing parameters such as Mode I …

Optimization Of Insertion Holes And Anchor Design For Cylinder Shaped Toggle Type Suture Anchors, Adam Fedenia

Masters Theses

This research was performed to optimize insertion holes and anchor design for cylinder shaped toggle type suture anchors. Four types of anchors were investigated in terms of pull strength and design in acrylic plate and pig bone. They included small type A and B anchors and large type A and B anchors.

Pull strength trends suggest that the small type anchors behave similarly since their external dimensions are identical, with the exception of type A anchor having a hole running from one end of the cylinder to the other like a pipe. It was found that the suture would fail …

Flange Bolt Failure Analysis, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

Failure cause investigation of flange bolts from the bi-axial shaft fatigue test rig was carried out and crack growth rates in combined bending and torsion conditions were determined. Flange bolts are used in gas turbine engines that are pre-torqued exerting bending and torsion fatigue situation arising from high centrifugal stresses. The fracture surface features were characteristic of bending fatigue (BF), where striations were observed, a distinct area within which conjoint bending and torsion fatigue (CBTF) features were documented, and a region between the BF and CBTF, a region of overloading (OL), where ductile dimples were observed. Striations dominated within BF …

Optimal Stimulus Electrode Dipole Orientation, Robert B. Szlavik, Hubert De Bruin

Biomedical Engineering

The elicited M-Wave that results from the surface stimulation of the median nerve is highly dependent upon the geometric orientation of the stimulus electrode dipole. This phenomenon could make standardization of M-Wave measurements between tests performed on a single subject problematic. We present an experimental paradigm that illustrates this variability in terms of an estimate of the slope of the M-Wave peak potential versus stimulus current amplitude and the minimum stimulus current required to consistently elicit a minimal response. The design of an automated instrument for selecting the optimal stimulus electrode dipole orientation based on the electrode orientation experiment is …

The Effects Of Testing Methods On The Flexural Fatigue Life Of Human Cortical Bone, L. V. Griffin, J. C. Gibeling, R. B. Martin, V. A. Gibson, S. M. Stover

Biomedical Engineering

A flexural model of four-point bending fatigue that has been experimentally validated for human cortical bone under load control was used to determine how load and displacement control testing affects the fatigue behavior of human cortical bone in three-point and symmetric four-point bending. Under load control, it was predicted that three-point bending produced no significant differences in fatigue life when compared to four-point bending. However, three-point bending produced less stiffness loss with increasing cycles than four-point bending. In four-point bending, displacement control was predicted to produce about one and a half orders of magnitude greater fatigue life when compared to …

Aneuploidy Frequencies In Semen Fractions From Ten Oligoasthenoteratozoospermic Patients Donating Sperm For Intracytoplasmic Sperm Injection, Jerome Pfeffer, Myung-Geol Pang, Stanton F. Hoegerman, Christopher J. Osgood, M. W. Stacey, Jacob Mayer, Sergio Oehninger, William G. Kearns

Biological Sciences Faculty Publications

Objective: To determine aneuploidy frequencies in pellet and swim-up semen fractions from 10 infertile men with severe oligoasthenoteratozoospermia (OAT) who were donating sperm for intracytoplasmic sperm injection and to determine whether the swim-up isolation method would successfully separate aneuploid from haploid sperm.

Design: Prospective study.

Setting: Infertility clinic and molecular genetics laboratory.

Patient(s): Ten patients with severe OAT.

Intervention(s): Cytogenetic analyses by fluorescence in situ hybridization to determine aneuploidy frequencies for chromosomes 1, 13, 18, 21, X, and Y in sperm from swim-up and pellet fractions.

Main Outcome Measure(s): Gametic aneuploidy was scored in sperm fractions separated by the swim-up …

Mechanics Of Cpr Performed With The Patient On A Soft Bed Versus A Hard Surface, John M. Boe, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Objective: To study the effects of underlying bed softness versus stiffness on the effectiveness of chest compressions in CPR. Methods: For a wide range of bed stiffness constants, mathematical models describing compression of the human chest supported by a hospital bed were created for an adult thorax experiencing either a sinusoidal compressive force or a sinusoidal sternal displacement. Results: With 5 cm peak displacement, sternum-to-spine compression fell from 4.3 to 1.0 cm, and peak power fell from 59 to 23 Watts, as bed stiffness decreased from 50,000 to 5,000 N/m. Less than 35% of maximal chest compression occurred at a …

The Certified Safe Farm Project In Nebraska: The First Year, Jerry Jaspersen, Susanna Von Essen, Pam List, Larry Howard, David Morgan

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Potentially preventable death, disabling injury, and serious illness are very common secondary to work in production agriculture in Nebraska and elsewhere. The traditional approach to farm safety has consisted largely of education designed to prevent traumatic injury. While education is of critical importance, additional incentives may be needed to reduce fatal and non-fatal events to an acceptable level. The Certified Safe Farm concept was developed in collaboration with two Nebraska health insurance companies. The program consists of combining an on-farm safety assessment and occupational health screening with an education program. The incentive to complete this program is to be eligible …

Nitrate Leaching In Irrigated Corn And Soybean In A Semi-Arid Climate, N. L. Klocke, Darrell G. Watts, J. P. Schneekloth, Don R. Davison, R. W. Todd, Anne M. Parkhurst

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Nitrate-nitrogen leached from the root zone of land in intensive corn production is a major groundwater contaminant in some of the intensively irrigated regions of the western Cornbelt, including central and western Nebraska. To obtain a clearer understanding of the amount and timing of nitrate leaching losses from irrigated crops, 14 monolithic percolation lysimeters were installed in 1989-1990 in sprinkler irrigated plots at the University of Nebraska’s West Central Research and Extension Center near North Platte, Nebraska. The lysimeters were used to provide a direct measure of leachate depth from continuous corn and a corn-soybean rotation. Both cropping systems were …

Wax Yield Of Grain Sorghum (Sorghum Bicolor) As Affected By Mechanical Harvesting, Threshing, And Handling Methods, K. R. Lochte-Watson, Curtis L. Weller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Wax is found on the outer layer of the grain sorghum (Sorghum bicolor) kernel. Current harvesting and handling techniques cause abrasion and breakage, thereby potentially reducing wax yield from sorghum kernels. The purpose of this study was to determine wax yield of sorghum after mechanical harvesting and handling and to compare wax yield of whole and broken sorghum kernels. Combine threshing and auger conveying of grain caused abrasion and breakage, which reduced the wax yield by 5%. The monitored process in this experiment included a cleaning system which reduced the amount of broken kernels and sorghum particles, increasing …

Opto-Electronic Sensor System For Laboratory Measurement Of Planter Seed Spacing With Small Seeds, Y. Lan, Michael F. Kocher, John A. Smith

Department of Agricultural and Biological Systems Engineering: Faculty Publications

An opto-electronic sensor system for measuring seed spacing uniformity with different types of seeds is described in this paper. It consisted of a rectangular photogate block (124 × 92 mm) with 24 phototransistors (diameter, 3 mm) receiving light beams from 24 light emitting diodes (diameter, 3 mm) opposite them, a digital input/output board in a personal computer, and power supplies. The opto-electronic system was tested by comparing seed spacing measurements obtained from the opto-electronic system with measurements of the same seed spacings obtained from a grease belt test stand. The tests were conducted with different types of seeds including regular-pelleted …

Belts Vs Tires, Belts Vs Belts, Tires Vs Tires, Leonard L. Bashford, Michael F. Kocher

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Tractive performance comparisons among two different width rubber belt tracks, 46 cm (18 in.) and 81 cm (32 in.) wide, and two different size rear tires, 710/70R38 and 18.4R46, were made on two different surface conditions. The belts were tested on a Caterpillar 55 tractor equipped with the Mobil-trac™ system and the tires on a John Deere 8400 mechanical front-wheel-drive (MFWD) tractor. The performance tests were completed on two surfaces, one being a non-tilled wheat stubble field and the second, the wheat stubble field tilled approximately 23 cm (9 in.) deep with a Noble blade sweep. Performance comparisons using tractive …

Seepage Characteristics And Hydraulic Properties Of A Feedlot Runoff Storage Pond, David B. Parker, Dean E. Eisenhauer, Dennis D. Schulte, John A. Nienaber

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Water and chemical transport were investigated beneath a 22-year-old beef feedlot runoff storage pond. Soil and sludge samples were collected from 14 borings to 6.1-m depths in a cross-section across the pond. The soils consisted of silt loam and clay loam, and the groundwater level was about 30 m beneath the land surface. Soil samples were analyzed for pH, NO₃-N, NH₄-N, Cl, P, K, SO₄-S, TKN, and organic matter. Physical and hydraulic properties were measured on undisturbed samples of soil and sludge to compare saturated hydraulic conductivity, moisture release characteristics, and bulk density. Saturated …

Efficacy Of Beam-Hardening Correction For Vascular Morphometry Using 3d Conebeam Micro-Ct, Roger H. Johnson, Jiang Hsieh, Robert C. Molthen, Christopher A. Dawson

Biomedical Engineering Faculty Research and Publications

No abstract provided.

An Iterative Approach To The Beam Hardening Correction In Cone Beam Ct (Proceedings), Jiang Hsieh, Robert C. Molthen, Christopher A. Dawson, Roger H. Johnson

Biomedical Engineering Faculty Research and Publications

No abstract provided.

A Continuous Process For The Conversion Of Vegetable Oils Into Methyl Esters Of Fatty Acids, Hossein Noureddini, D Harkey, V Medikonduru

Papers in Biomaterials

A continuous process for the transesterification of triglycerides to methyl esters was investigated in a pilot plant. The process was equipped with a motionless and a high-shear mixer. The experimental studies explored variations in the mixing intensity, stoichiometry, and catalyst concentration on the overall conversion. The combined as well as individual effect of mixers was examined. The developed process resulted in high conversions of vegetable oils into methyl esters. Conversion of triglycerides to methyl esters in excess of 98% was achieved. Larger excess amounts of alcohol favored higher conversions. The motionless and high-shear mixers each provided adequate mixing for the …

Enzymatic Glycerolysis Of Soybean Oil , Hossein Noureddini, S E. Harmeier

Papers in Biomaterials

Enzymatic glycerolysis of soybean oil was studied. Of the nine lipases that were tested in the initial screening, Pseudomonas sp. resulted in the highest yield of monoglycerides. Lipase from Pseudomonas sp. was further studied for the influence of temperature, thermal stability, enzyme/oil ratio, and glycerol/oil ratio. A full factorial optimization approach was performed. The following conditions were tested over the specified ranges: temperature (30?70°C), thermal stability (30?70°C), enzyme/oil ratio (0.05?0.2 g enzyme/10 g oil), glycerol/oil ratio (1:1?3:1 glycerol/oil molar ratio) and 1 h reaction time. The stability of the enzyme at the reaction temperature was also incorporated as a separate …

Method For Improving Consolidation Of Powder Resin, David A. Pienkowski, Eric A. Grulke, Robert J. Jacob

Biomedical Engineering Faculty Patents

A method for improving consolidation of powder resin is provided. The method broadly includes the steps of: (1) sorting particles of the powder resin according to their diameter; (2) combining the sorted particles having a first diameter D1 with the sorted particles having a second diameter D2 so as to form a particle mixture; (3) applying a vibration to the particle mixture; (4) heating the particle mixture; and (5) delivering the particle mixture through a nozzle or into a mold. The particle diameters D1 and D2 are chosen so that once combined there is optimal close packing of the three-dimensional …

Analysis Of Multi-Lead Qt Dispersion By Means Of An Algorithm Implemented On Labview, Zafer Sahinoglu

Theses

QT dispersion measurement is significant in diagnostic ECG, and several methods are proposed in the literature to implement QT measurement.

This study consists of two parts: The first part was the development of an algorithm to measure both QT interval and QT dispersion. To check the reliability of the algorithm, 25 single channel ECGs were recorded and their QT intervals were computed. On two subjects, three and four lead ECG data were recorded respectively and their QT dispersions were statistically analyzed. Another part of this study dealt with the effect of the electric dipole of the heart on QT dispersion. …

Measurement Of The Baroreceptor Sensitivity Index (Brsi) In The Frequency Domains, Tanvir Raquib

Theses

Time domain analysis for calculating the Baroreceptor Sensitivity Index (BRSI) did not always provide an accurate result. It also had another limitation in that it could not show the influence of the autonomic nervous system for different subjects. The correlation coefficient is a mechanism that was used to either accept or reject the BRSI values in the time domain but the correlation coefficient values changed drastically depending on how many sample points were selected for the calculation.

On the other hand, frequency domain analysis for the BRSI calculation was relatively easier and provided more accurate information compared to the time …