Biomedical Engineering and Bioengineering Commons^™

3d Micro-Ct For Functional Genomics, R. H. Johnson, Robert C. Molthen, Christopher C. Hanger, Kelly Lynn Karau, Steven Haworth, Christopher Dawson

Biomedical Engineering Faculty Research and Publications

No abstract provided.

The Relationship Between Basic Multicellular Unit Activation And Origination In Cancellous Bone, C. J. Hernandez, S. J. Hazelwood, R. B. Martin

Biomedical Engineering

Activation frequency is often used as a measure of basic multicellular unit (BMU) activity in cancellous bone. However, activation frequency expresses the rate of BMU appearance in a histologic slide and not the rate of origination, which is a more physiologic indicator of remodeling activity and is necessary for the development of BMU-level bone remodeling simulations. Using identical assumptions to those for calculating the activation frequency, it is shown that the origination frequency in cancellous bone is equal to the activation frequency divided by the total distance traveled by the BMU and its width.

Mri Techniques For Cardiovascular Imaging, Roderic I. Pettigrew, John N. Oshinski, George P. Chatzimavroudis, W. Thomas Dixon

Chemical & Biomedical Engineering Faculty Publications

Over the last several years, cardiovascular MRI has benefited from a number of technical advances which have improved routine clinical imaging techniques. As a result, MRI is now well positioned to realize its longstanding promise of becoming the comprehensive cardiac imaging test of choice in many clinical settings. This may be achieved using a combination of basic advanced techniques. In this overview, the basic cardiac MRI techniques which are clinically useful are reviewed, and the recent technical advances which are clinically promising are described. These advances include routine black blood and cine bright blood techniques that are high speed (slice), …

A Defect In Interleukin 12-Induced Activation And Interferon Gamma Secretion Of Peripheral Natural Killer T Cells In Nonobese Diabetic Mice Suggests New Pathogenic Mechanisms For Insulin-Dependent Diabetes Mellitus., Marika Falcone, Brian Yeung, Lee Tucker, Enrique Rodriguez, Nora Sarvetnick

Journal Articles: Regenerative Medicine

The function of natural killer T (NKT) cells in the immune system has yet to be determined. There is some evidence that their defect is associated with autoimmunity, but it is still unclear how they play a role in regulating the pathogenesis of T cell-mediated autoimmune diseases. It was originally proposed that NKT cells could control autoimmunity by shifting the cytokine profile of autoimmune T cells toward a protective T helper 2 cell (Th2) type. However, it is now clear that the major function of NKT cells in the immune system is not related to their interleukin (IL)-4 secretion. In …

Toward Designing The Optimal Total Cavopulmonary Connection: An In Vitro Study, Ann E. Ensley, Patricia Lynch, George P. Chatzimavroudis, Carol Lucas, Shiva Sharma, Ajit P. Yoganathan

Chemical & Biomedical Engineering Faculty Publications

Background. Understanding the total cavopulmonary connection (TCPC) hemodynamics may lead to improved surgical procedures which result in a more efficient modified circulation. Reduced energy loss will translate to less work for the single ventricle and although univentricular physiology is complex, this improvement could contribute to improved postoperative outcomes. Therefore to conserve energy, one surgical goal is optimization of the TCPC geometry. In line with this goal, this study investigated whether addition of caval curvature or flaring at the connection conserves energy.

Methods. TCPC models were made varying the curvature of the caval inlet or by flaring the anastomosis. …

Quantification Of Pulmonary Arterial Wall Distensibility Using Parameters Extracted From Volumetric Micro-Ct Images, Roger H. Johnson, Kelly Lynn Karau, Robert C. Molthen, Christopher A. Dawson

Biomedical Engineering Faculty Research and Publications

Stiffening, or loss of distensibility, of arterial vessel walls is among the manifestations of a number of vascular diseases including pulmonary arterial hypertension. We are attempting to quantify the mechanical properties of vessel walls of the pulmonary arterial tree using parameters derived from high-resolution volumetric x-ray CT images of rat lungs. The pulmonary arterial trees of the excised lungs are filled with a contrast agent. The lungs are imaged with arterial pressures spanning the physiological range. Vessel segment diameters are measured from the inlet to the periphery, and distensibilities calculated from diameters as a function of pressure. The method shows …

Wide Tires, Narrow Tires, Leonard L. Bashford, Michael F. Kocher, Todd S. Tibbetts

Biological Systems Engineering: Papers and Publications

Tractive performance comparisons among five different size tires were made on two different surface conditions, a wheat stubble field and a tilled wheat stubble field. Radial 18.4R46, 20.8R42 and 710/70R38 radial tires; and bias 750/65-38 and 850/55-42 tires were used. Instrumentation to evaluate tractive performance was installed on a two-wheel drive and a mechanical front wheel drive agricultural tractor. Axle torques, drawbar pull, travel speed, and engine rpm were recorded for a series of drawbar pulls on the two soil surfaces. Tractive performance evaluations among the tires were made by comparing the relationships of dynamic traction ratio to slip, tractive …

Nutrient Balance On Nebraska Livestock Confinement Systems, Richard K. Koelsch, Gary Lesoing

Biological Systems Engineering: Papers and Publications

Managing the environmental risk associated with livestock production is a significant challenge. Nitrogen and phosphorus are commonly implicated as the sources of ground and surface water quality problems associated with livestock production. The degree of imbalance between these nutrient inputs and the managed nutrient outputs for a livestock operation defines the magnitude of potential environmental risk and provides insight as to the underlying causes of these challenges. A nitrogen and phosphorus balance was constructed for 33 Nebraska confinement livestock operations. Twenty-five and 17 of these operations experienced significant nitrogen and phosphorus imbalances, respectively (50% more nutrient inputs than outputs). Nutrient …

The Effect Of Stimulus Current Pulse Width On Nerve Fiber Size Recruitment Patterns, Robert B. Szlavik, Hubert De Bruin

Biomedical Engineering

There have been theoretical studies presented that postulate a change in the stimulus current amplitude required to recruit nerve fibers with different stimulus current pulse widths. Based on these theoretical predictions, it has been suggested that the stimulus pulse width parameter may be used to selectively recruit fibers of different sizes and that this selectivity should increase with increasing distance from the stimulus electrode. In this paper, a simulation study of the recruitment patterns of a population of motor nerve fibers with a histologically accurate fiber diameter distribution is presented. Nerve fiber excitation simulations coupled with a time varying field …

In Vivo Electrical Stimulation Of Motor Nerves, Robert B. Szlavik

Biomedical Engineering

Stimulus waveform parameters and stimulation protocols are fundamental to the use of electrical stimulation in medical applications. This thesis presents new simulation and experimental procedures that for the first time can quantify the effects on nerve fiber recruitment patterns of variable stimulus waveform parameters, such as pulse width and changes in the stimulation protocol with respect to electrode orientation. The study of the effect of variable electrical stimulus waveform parameters and stimulation protocols is important from the perspective of therapeutic and diagnostic medicine. Variations in the stimulus waveform such as stimulus pulse width have been shown to offer some promise …

Phosphorus And Nitrogen In Runoff Following Beef Cattle Manure Of Compost Application, Bahman Eghball, John E. Gilley

Biological Systems Engineering: Papers and Publications

Manure or compost from beef cattle feedlots can be an excellent sources of nutrients and organic matter when added to soils, but they can also pollute runoff. We determined the effects of simulated rainfall on runoff losses of P and N, and EC and pH following application of manure and compost to a Sharpsburg silty clay loam (fine smectitic, mesic Typic Argiudoll) soil having grain sorghum [Sorghum bicolor (L.) Moench] and winter wheat (Triticum aestivum L.) residues. Manure, compost, and fertilizer were applied to no-till fields at rates required to meet N or P requirements for corn ( …

Anatomy Of Soft Tissues Of The Spinal Canal, Hogan Quinn, Jeffrey M. Toth

Biomedical Engineering Faculty Research and Publications

Background and Objectives.

Important issues regarding the spread of solutions in the epidural space and the anatomy of the site of action of spinal and epidural injections are unresolved. However, the detailed anatomy of the spinal canal has been incompletely determined. We therefore examined the microscopic anatomy of the spinal canal soft tissues, including relationships to the canal walls.

Methods.

Whole mounts were prepared of decalcified vertebral columns with undisturbed contents from three adult humans. Similar material was prepared from a macaque and baboon immediately on death to control for artifact of tissue change after death. Other tissues examined included …

Z-Protected Glutamic Acid-Based Biodegradable Thermoplastic And Thermosetting Polyesters: Synthesis And Characterization, R M. Tadros, Hossein Noureddini, Delmar C. Timm

Papers in Biomaterials

Biodegradable polymers were formed from N-benzyloxycarbonyl-L-glutamic acid with the comono-mers ethylene glycol, diglycidyl ether of 1,4-butanediol, and diglycidyl ether of bisphenol A. The three polymers were a linear and a rosslinked heterochain polyester and a crosslinked polyester that contained aromatic units within its network chains. The thermoplastic resin and the soluble fractions for the thermo-setting resins were characterized by gel permeation chromatography. Conversions for carboxylic acid were determined by titrations. A quality, 22,000 molecular weight thermoplastic resin was formed. The two ther-mosets were cured past their gel points. Gelation analysis revealed that the relative rate constants for the sequential oxirane/ …

The Use Of Recombinant Human Bone Morphogenetic Protein 2 (Rhbmp-2) To Promote Spinal Fusion In A Nonhuman Primate Anterior Interbody Fusion Model, Brian P. Hecht, Jeffrey S. Fischgrund, Harry N. Harkowitz, Lori Penman, Jeffrey M. Toth, Ali Shirkhoda

Biomedical Engineering Faculty Research and Publications

Study Design. A study on the efficacy of recombinant human bone morphogenetic protein 2 (rhBMP-2) in a nonhuman primate anterior interbody fusion model.

Objectives. To investigate the efficacy of rhBMP-2 with an absorbable collagen sponge carrier to promote spinal fusion in a nonhuman primate anterior interbody fusion model.

Summary of Background Data. RhBMP-2 is an osteoinductive growth factor capable of inducing new bone formation in vivo. Although dosage studies using rhBMP-2 have been performed on species of lower phylogenetic level, they cannot be extrapolated to the primate. Dosage studies on nonhuman primates are essential before proceeding with human primate application. …

Implant Pre-Treated For Reducing The Generation Of Wear Particulates, David A. Pienkowski, Kwon-Yong Lee

Biomedical Engineering Faculty Patents

A method is provided for reducing the amount of wear particulates generated by a total joint orthopaedic implant. The implant consists of two matched articulating components wherein at least one of the components is made of polymer or other material with similar physical properties. The method includes the steps of placing the total joint orthopaedic implant in a fluid bath and articulating the implant in the fluid bath for at least 1,000 cycles. The articulation may be performed in three stages. In the first, the implant is articulated under a load of substantially 0.1-500 Newtons with sliding speeds of substantially …

Liquid-Phase Catalytic Oxidation Of Unsaturated Fatty Acids , Hossein Noureddini, M Kanabur

Papers in Biomaterials

Liquid-phase catalytic oxidation of oleic acid with hydrogen peroxide in the presence of various transition metal/metal oxide catalysts was studied in a batch autoclave reactor. Azelaic and pelargonic acids are the major reaction products. Tungsten and tantalum and their oxides in supported and unsupported forms were used as catalysts. Alumina pellets and Kieselguhr powder were used as supports for the catalysts. Tungsten, tantalum, molybdenum, zirconium, and niobium were also examined as catalysts. Tertiary butanol was used as solvent. Experimental results concluded that tungsten and tungstic oxide are more suitable catalysts in terms of their activity and selectivity. The rate of …

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 …

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 …

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 …

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 …

In Vitro Transport In Canaliculi Of Rat Femora Under Cyclic Loading, B. Li, Timothy L. Norman

Engineering and Computer Science Faculty Publications

No abstract provided.

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.

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

Biological Systems Engineering: Papers and 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

Biological Systems Engineering: Papers and 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 …

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

Biological Systems Engineering: Papers and 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 …

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

Biological Systems Engineering: Papers and 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 …

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

Biological Systems Engineering: Papers and 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

Biological Systems Engineering: Papers and 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 …