Biomedical Engineering and Bioengineering Commons^™

Scanning Local‐Acceleration Microscopy, Nancy Burnham, A. Kulik, G. Gremaud, P. Gallo, F. Oulevey

Nancy A. Burnham

By adapting a scanning force microscope to operate at frequencies above the highest tip–sample resonance, the sensitivity of the microscope to materials’ properties is greatly enhanced. The cantilever’s behavior in response to high‐frequency excitation from a transducer underneath the sample is fundamentally different than to its low‐frequency response. In this article, the motivations, instrumentation, theory, and first results for this technique are described.

Materials’ Properties Measurements: Choosing The Optimal Scanning Probe Microscope Configuration, Nancy Burnham, G Gremaud, A Kulik, P Gallo, F Oulevey

Nancy A. Burnham

Rheological models are used to represent different scanning probe microscope configurations. The solutions for their static and dynamic behavior are found and used to analyze which scanning probe microscope configuration is best for a given application. We find that modulating the sample at high frequencies results in the best microscope behavior for measuring the stiffness of rigid materials, and that by modulating the tip at low frequencies and detecting the motion of the tip itself (not its position relative to the tip holder) should be best for studying compliant materials in liquids.

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Signal Processing Techniques In Heart Rate And Systolic Arterial Blood Pressure Variability Studies, Christopher O'Bara

Theses

Power spectral analysis of heart rate and systolic arterial blood pressure variability provides a window to the activity of the autonomic nervous system. To derive power spectra from raw blood pressure and electrocardiogram signals, many steps of signal processing must be performed. Most popular methods of spectral analysis require evenly spaced samples; therefore interpolation and resampling techniques must be used.

The results of the present study indicate that different interpolation techniques result in spectral distortions that vary depending upon the interpolation methods used as well as physiological parameters such as heart and respiration rate. Different interpolation methods applied to heart …

Armature Position Sensor For A Relay, G. Stephen Perreira, Richard L. Kutin, Lanny V. Griffin

Biomedical Engineering

A sensor for use with high-power solenoid-actuated relays, and for detecting and signalling relay armature position and hence the actuation state of the relay. The sensor is external to a sealed chamber in which the relay contacts and armature system are positioned, and includes a permanent magnet, the flux path of which includes the relay armature and base. Armature movement to close the relay alters the flux path to operate a reed switch adjacent the magnet, and the condition of the reed switch signals the unactuated or actuated state of the relay.

Artifactual Nonlinearity Due To Wear Grooves An Friction In Four-Point Bending Experiments Of Cortical Bone, L. V. Griffin, J. C. Gibeling, V. A. Gibson, R B. Martin, S. M. Stover

Biomedical Engineering

Experiments and analyses were performed to determine th e cause of a nonlinear force-deflection response observed in four-point flexural fatigue of beams ofcortical bone machined from the mid-diaphysis of the equine third metacarpus. Observable grooves which formed on the beam surface at supports and load noses were found to be the primary cause of the nonlinearity. An additional geometric nonlinearity at large deflections revealed by finite element modeling may be minimized by using the smallest diameter supports and load noses recommended in ASTM 790. However, frictional constraint of the beams at the load noses and supports can occur at low …

Development Of A Biologically Based Aerobic Composting Simulation Model, Dennis P. Stombaugh, Sue E. Nokes

Biosystems and Agricultural Engineering Faculty Publications

A relatively simple dynamic model based on microbial process kinetics has been developed for aerobic composting. Differential equations describing microbial, substrate, and oxygen concentrations, as well as moisture and temperature profiles have been derived as a function of vessel size and aeration rate. Microbial biomass growth was described using Monod growth kinetics as a function of degradable substrate concentration, oxygen concentration, moisture content, and compost temperature. Facility and fan operating costs have been included to permit economic optimization of the process. Predicted results demonstrated the ability of the model to quantify and describe the influence of multiple interacting factors (temperature, …

Lai - Introduction To Continuum Mechanics ترجمه فارسي کتاب مکانيک محيط پيوسته ويرايش سوم, Dr Alireza Zolfaghari

Dr Alireza Zolfaghari

No abstract provided.

Validation Of Energy Dispersive X-Ray Spectrometry As A Method To Standardize Backscattered Electron Images Of Bone, E. G. Vajda, R. D. Bloebaum, J. G. Skedros

Cells and Materials

The use of backscattered electron (BSE) imaging as a tool for the qualitative measurement of mineral content in bone has been well documented. The challenge still remains to develop BSE imaging as a tool for quantitative mineral content analysis in bone. The limiting factor has been the ability to standardize the BSE signal within and between laboratories. Energy dispersive x-ray spectrometry (EDX) has been proposed as a method to standardize the BSE operating environment. The goal of this study is to investigate the relationship between EDX-determined wt.% Ca measurements and BSE graylevels. A comparison with traditional ash content measurements will …

Laboratory Growth Systems In Biofilm Research, Julian W. T. Wimpenny

Cells and Materials

The huge variety of ecosystems that we collectively refer to as "biofilm" is reflected by the numerous different systems available to grow them in the laboratory. The relationship between in situ systems, microcosms and laboratory models is defined and discussed. The first two represent holistic approaches designed to assess the structure and function of particular biofilms: the last is analytical and reductionist, aiming to isolate specific functions of biofilms in order to understand properties that can apply to biofilm in general. Properties of a model can be completely understood whilst this is unlikely with natural ecosystems because of the possibility …

Initial Biodeterioration Of Silicone Rubber By C. Albicans And C. Aropicalis Strains Isolated From Voice Prostheses, H. C. Van Der Mei, B. Van De Belt-Gritter, F. Dijk, H. J. Busscher

Cells and Materials

Silicone rubber voice prostheses m patients after total laryngectomy become rapidly colonized by a biofilm, consisting of yeasts and bacteria. An especially troublesome feature of these biofilms is the ingrowth into the silicone rubber by colonizing yeasts. Microcolonies of ingrowing yeasts have been frequently observed on explanted voice prostheses after 3-4 months use. Incubation of silicone rubber samples in a modified Robbins device with a culture of Candida tropicalis, isolated from a Groningen button voice prosthesis, while passing the yeasts through a cycle of feasts (7 days) and famine (also 7 days) demonstrated, by electron microscopy, the onset of the …

Investigation Of Bone And Calcium Phosphate Coatings And Crystallinity Determination Using Raman Microspectroscopy, C. J. De Grauw, J. D. De Bruijn, C. Otto, J. Greve

Cells and Materials

Conventional spontaneous Raman micro-spectroscopy was used for the investigation of bone and calcium phosphate coatings on bone-implant surfaces. Chemical and structural changes at the bone-coating interface could be monitored on a microscopic scale. It was shown that the crystallinity did not vary within the crystalline apatite and amorphous calcium phosphate coatings, while the density within each coating did vary. Different degrees of crystallinity in coatings were investigated for a series of plasma-sprayed apatite coatings. It is concluded that Raman microspectroscopy is an easy non-destructive way to obtain information about the apatite structure and the degree of crystallinity.

Effects Of Solidification Conditions And Heat Treatment On The Microstructure And Vickers Hardness Of Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, Stanley G. Vermilyea, Efstratios Papazoglou, John C. Mitchell, Alan B. Carr

Cells and Materials

Two representative Pd-Cu-Ga dental alloys, one with a dendritic as-cast microstructure containing a eutectic interdendritic constituent and the other with an equiaxed fine-grained as-cast microstructure containing a near-surface eutectic constituent, have been subjected to rapid quenching following casting, in addition to the conventional bench cooling recommended by the manufacturers. The quenched alloys were subsequently heat treated at temperatures of 1200°, 1500° and 1800 op that span the range of the firing cycles for dental porcelain. Scanning electron microscopic examination showed that the lamellar eutectic constituents normally present in the microstructures of the as-cast and bench-cooled alloys persisted when the alloys …

Gap Junctional Intercellular Communication In Bone, Henry J. Donahue, Monique A. Vander Molen, Clare E. Yellowley, Zhongyong Li

Cells and Materials

Gap junctional intercellular communication has been demonstrated in bone cells and may contribute to the mechanism by which osteoblasts integrate and amplify extracellular signals, both chemical (hormonal) and biophysical (electrical and mechanical). Connexin 43 (Cx43) is the predominant gap junction protein expressed by bone cells. Experiments with osteoblastic cells in which Cx43 expression was diminished by antisense transfection demonstrate that cell-to-cell coupling in osteoblastic ROS 17/2.8 cells is via gap junctions composed of Cx43. Cellular networks of these coupling deficient clones are dramatically less responsive to parathyroid hormone (PTH) suggesting that coupling contributes to hormonal responsiveness. Furthermore, PTH per se …

A New Device For Performing Simultaneous Sterno-Thoracic Cardiopulmonary Resuscitation (Sst-Cpr), Deepak S. Gupta

Theses and Dissertations

There are two different physiological mechanisms that cause blood to circulate around the human body during cardiopulmonary resuscitation. The "cardiac pump" generates blood flow by squeezing blood out of the heart as the sternum is depressed. The "thoracic pump" generates flow by forcing blood out of the heart and the great vessels as the intrathoracic pressure rises due to chest compression.

To date, all CPR techniques try to circulate blood during cardiac arrest by exploiting elite; the cardiac pump or the thoracic pump mechanism of blood flow. No mechanical CPR device thus far invented has tried to exploit both mechanisms …

Effect Of Light Source On The Sorting Performance Of A Vision-Based Robot System, Johnny T. Li

Dissertations and Theses @ UNI

Industries look toward computer vision as a means to automate materials handling. To make this choice more appealing, useful and feasible vision applications must be explored. However, illuminance variation in the factory environment can undermine the capability and applicability of vision-based control systems. The purposes of this study were (a) to design and develop a vision-based robot material sorting system, (b) to determine the optimal settings for this system under fluorescent and incandescent lighting for two different color parts on a moving conveyor, and (c) to determine the sorting performance of this system under each light source.

The main components …

Time Course Of Recruitment, Pit Formation And Apoptosis Of Osteoclast Populations On Dentin In Vitro, Jihyun Kang, Rigoberto Cornejo, Kevin J. Hirokawa, Susan M. Digiorgio, Darlene F. Howard, Susan F. Silverton

Cells and Materials

The resorptive capacity of osteoclasts in vitro has been used as an indicator of bone resorption. However, the kinetics of osteoclast development and senescence is not well understood. It has been noted that mononuclear precursors migrate to calcified substrate and after multi-nucleation become competent bone resorbing cells. Osteoclasts, once finished a wave of resorption, become senescent. In order to determine the survival characteristics of osteoclast populations involved in calcified tissue destruction, we have investigated the time course of the recruitment to dentin and apoptosis of osteoclasts. We have established the linkage between these measurements and the time course of the …

Biodegradation Of A Nano-Hydroxyapatite/Collagen Composite By Peritoneal Monocyte-Macrophages, F. Z. Cui, C. Du, X. W. Su, X. D. Zhu, N. M. Zhao

Cells and Materials

A nano-hydroxyapatite/collagen composite was prepared by precipitation of hydroxyapatite from an aqueous solution onto collagen. Mouse peritoneal macrophages were used to investigate the in vitro biodegradation of the composite. The results showed the mechanism of phagocytosis and extracellular degradation process. The cells that belong to the mononuclear phagocyte system showed some morphological characteristics similar to those of osteoclasts and made pits on the composite surface. The local modification of the material surface by the cell was another phenomenon distinguishable from the degradation process. The degradation and modification made the material porous with a widely varying Ca/P ratio.

The Role Of Surface Characteristics In The Initial Adhesion Of Human Bone-Derived Cells On Ceramics, H. Zreiqat, O. C. Standard, T. Gengenbach, J. G. Steele, C. R. Howlett

Cells and Materials

The tissue/biomaterial interactions of three biomaterials of potential use in bone implants were studied in vitro. The mechanism of cell adherence to various ceramic substrata has been investigated by measurement of short term (90 minutes) cell attachment and spreading rate. We have determined the effect of two serum glycoproteins, fibronectin and vitronectin, on the adhesion of human bone derived cells (HBD-cells) cultured on three different types of ceramics {alumina (Al₂O₃), hydroxyapatite (HAP) and yttria-doped tetragonal zirconia polycrystal (Y-TZP)} . The attachment of HBD-cells to alumina and hydroxyapatite was approximately 60% of that to Y-TZP. Furthermore, …

The Influence Of A Fibrin-Coating Inside A Biodegradable Poly(Dl-Lactide-Ε-Caprolactone) Nerve Guide On Peripheral Nerve Regeneration, W. F. A. Den Dunnen, J. M. Schakenraad, B. Van Der Lei, A. J. Pennings, P. H. Robinson

Cells and Materials

The aim of this study was to evaluate the effect of a fibrin-coating on the inner surface of a biodegradable poly(DL-lactide-E-caprolactone) nerve guide on the speed and quality of the nerve regeneration. The nerve regeneration and orientation of the nerve fibers, as well as the fibrous tissue formation were evaluated. On the short term, nerve regeneration was slightly faster in the non-coated nerve guide. After longer implantation periods (≥ 4 weeks), nerve regeneration in the fibrin-coated nerve guides was characterized by a severe inflammatory response with large numbers of macrophages and polymorphonuclear cells (PMN's). This study clearly demonstrates that nerve …

Stability Of Liposomes Prepared From Archaeobacterical Lipids And Phosphatidylcholine Mixtures, G. D. Sprott, C. J. Dicaire, L. P. Fleming, G. B. Patel

Cells and Materials

In vitro stabilities of liposomes prepared from the total polar lipids (TPL) of various species of Archaeobacteria were compared with those made from egg phosphatidylcholine (EPC) and from mixtures of TPLIEPC. Stability was monitored by measuring the extent of leakage of entrapped dyes. Liposomes prepared from exclusively archaeobacteriallipids (coined archaeosomes), particularly those containing the bilayer spanning tetraether lipids, were generally stable to conditions such as storage at 37°C for greater than 7 days, exposure to phospholipase A₂, incubation with serum, and, to some extent, exposure to bile salts. In contrast, EPC liposomes were generally unstable to these conditions, …

Biofilm Mediated Calculus Formation In The Urinary Tract, Robert J. C. Mclean, David J. Stickler, J. Curtis Nickel

Cells and Materials

Mineralization and subsequent calculus formation is a common complication of biofilm infections. In the urinary tract, these infected calculi often arise from infections by urease-producing bacteria. Ammonia, liberated by bacterial urease activity, increases urine pH, resulting in the precipitation of Ca and Mg as carbonateapatite {Ca₁₀(PO₄,CO₃)₆(OH,CO₃)₂} and struvite (NH₄MgP0₄·6H₂O). These minerals become entrapped in the organic matrix which surrounds the infecting organisms and ultimately grow into mature calculi. When the causative organisms grow on urinary catheters and stents, the resulting mineralization can …

Heterogeneity Of Natural Biofilm Communities, J. R. Lawrence, D. R. Korber, G. M. Wolfaardt

Cells and Materials

Scanning confocal laser microscopy (SCLM) studies have shown that microbial biofilms consist of a spatially heterogeneous arrangement of bacterial cells, biogenic extracellular material, and void space. Biofilm architecture is dominated by the presence of cell aggregates interspersed by channels, the arrangement of which varies for different hydrodynamic regimes, ages, species composition, or nutrient status. This organization may regulate the flux of nutrients and oxygen, creating chemical microenvironments (Eh, pH) facilitating the growth of aerobic heterotrophs and anaerobes. The presence of microenvironments has been confirmed using laser microscopy and environmentally sensitive fluorescent probes. In addition, changes in cell number and growth …

The Effect Of Vitronectin And Other Extracellular Matrix Molecules On Endothelial Expansion And Plasminogen Activation, P. Anne Underwood, Penny A. Bean

Cells and Materials

Endothelial recovery following procedures used to alleviate blood vessel occlusion is modulated by the local extracellular matrix upon which it has to migrate and proliferate. This extracellular material is derived from vessel wall cells, and plasma proteins which bind to the exposed surfaces. We have demonstrated that vitronectin adsorbs efficiently to tissue culture polystyrene in competition with other plasma proteins, which suggests that it may adsorb to biomaterial surfaces in vivo. We have compared the adhesion, migration and proliferation of human umbilical artery endothelial cells on surface-coated vitronectin, with other extracellular matrix molecules encountered in this environment, namely fibronectin, …

Collagen Fibres Are Not Required For Initial Matrix Mineralization By Bone Cells, M. M. Hosseini, S. A. F. Peel, J. E. Davies

Cells and Materials

Passaged primary cultures of young adult rat bone marrow cells were maintained in medium containing combinations of the supplements dexamethasone, ascorbic acid and Na-ß-glycerophosphate. The cultures were examined by both light and scanning electron microscopy (with additional energy dispersive X-ray analysis). In cultures with fully supplemented medium, an extracellular matrix formed at the culture dish surface, beneath developing bone nodules; this matrix was mineralized but collagen-fibre free and corresponded to that which we have reported previously as the equivalent of the cement line in vivo. In selected samples this interfacial, cement line, matrix was analyzed by X-ray …

Perturbations Of Periosteel Bone During Healing: Effect Of Non-Weight Bearing, Helen E. Gruber, Mary E. Kirchen, John R. Sweeney, William E. Anderson, G. June Marshall

Cells and Materials

Weight bearing (WB) is an important factor influencing bone remodelling. The present study evaluates the effects of weight bearing and non-weight bearing (S) (achieved by tail suspension and hindlimb elevation) on the healing of a fibular osteotomy in adult male rats. After 9, 18 or 36 days under WB or S conditions, periosteum near the callus formed at the osteotomy site was compared to periosteum of the contralateral fibula (which did not receive an osteotomy) or to periosteum of fibula of control animals which did not receive an osteotomy. Data show that periosteal bone healing is sensitive to alterations in …

Letter To The Editor: Biocompatibility And Reactogenicity Of Materials: A Semantic And Logical Analysis Of Definitions And Their Practical Significance, Leonid I. Slutskii, Janis J. Vetra

Cells and Materials

Any biomaterial implanted into a living body elicits a distinct local reaction. This reaction depends on the physical, physico-chemical and chemical properties of the material. The obvious term to designate this inherent property of a biomaterial to induce a local reaction is reactogenicity. Reactogenicity of a biomaterial is one of the main factors determining (together with other properties of the implanted device) the bio(non)compatibility of the implant. Such amplification of terminology which establishes differences between biocompatibility as a generalized characteristic of biomaterials in all their interrelations with the host's organism and the influences on local processes around implants, makes the …

Pelargonic Acid In Enhanced Oil Recovery, Hossein Noureddini, M L. Rempe

Papers in Biomaterials

Oxidation of monounsaturated iatty ac~dss,u ch as erucic and oleic acids, results in the for~nation of dibasic fatty acids, such as brassylic and azelaic acids. Dibasic acids find many inclustrial applications. Prlargon~ca cid is the co-product oi the process. Expanded use oi dibasic acids would require an expansion in the existing and possihiy new uses for pelargoriic acid and its derivatives. In this study, the potential for using pe!argonic acid in enhanced oil recovery is investigated. Experimental results are presented ior the enhanccd oil recover" by waterilooding with the aid oi a surfactan;. In sifu iormation of surfactant at the …

Grazing And Haying Effects On Runoff And Erosion From A Former Conservation Reserve Program Site, John E. Gilley, B. D. Patton, P. E. Nyren, J. R. Simanton

Biological Systems Engineering: Papers and Publications

Grazing and haying effects on runoff and erosion from a former Conservation Reserve Program (CRP) site near Streeter, North Dakota, were determined. Treatments included undisturbed CRP, twice-over rotational grazing, season-long grazing, haying, and burning. Runoff and erosion were measured from simulated rainfall which was applied to 3.7 x 10.7 m (12.0 X 35.1 ft) plots. Following an initial stabilization period, no significant difference in runoff or erosion was found between the season-long grazing and burned treatments. Use of the CRP site for grazing or haying resulted in a significant increase in runoff compared to leaving the area in an undisturbed …

Heat Curing Of Soy Protein Films, A. Gennadios, V. M. Ghorpade, Curtis L. Weller, M. A. Hanna

Biological Systems Engineering: Papers and Publications

Modification of soy protein film properties by heat-curing was studied. Glycerin-plasticized films were cast from alkaline aqueous solutions of soy protein isolate. Films were heated at 80 or 95°C for 2, 6, 14, or 24 h. Tensile strength (TS), elongation at break (E), moisture content (MC), water solubility (WS), water vapor permeability (WVP), and color of heated and control films were measured. Heated films had increased TS and +b (yellowness) Hunter color values and reduced E, MC, WS, and WVP values. These effects were enhanced as heating time and temperature increased.