Engineering Commons^™

A Novel In Vitro Model To Study The Calcification Of Biomaterials, Q. Liu, J. Weng, J. G. C. Wolke, J. R. De Wijn, C. A. Van Blitterswijk

Cells and Materials

A novel in vitro model based on a solution mainly composed of sodium, calcium, chloride and phosphate ions, was developed to study the calcification of biomaterials at near physiological conditions. This model, due to its ability to quickly calcify the tested materials, is called Accelerated Calcification Solution (ACS). Polyactive ™ 30170, Polyactive™ 70/30 and its composites with nano-apatite were used as testing materials because of their known calcification behaviour. The results showed that Polyactive™ 70/30 and its composites could calcify in ACS in a relatively short period, while the polymer without filler failed to induce calcium phosphate precipitation in more …

Peripheral Nerve Regeneration And Functional Nerve Recovery After Reconstruction With A Thin-Walled Biodegradable Poly(Dl-Lactide-Ε-Caprolactone) Nerve Guide, M. F. Meek, W. F. A. Den Dunnen, H. L. Bartels, A. J. Pennings, P. H. Robinson, J. M. Schakenraad

Cells and Materials

The aim of this study was to evaluate functional nerve recovery after reconstruction of a 1 em gap in the sciatic nerve of the rat, with a thin-walled biodegradable poly(DLLA-ε-CL) nerve guide. To evaluate both motor and sensory nerve recovery, walking track analysis and electrostimulation tests were carried out after implantation periods ranging from 3 to 26 weeks post-operatively. The first signs of functional nerve recovery could already be observed after 5 weeks. From the histological analysis, it could be concluded that most of the thin-walled nerve guides had collapsed. Despite collapsing, functional nerve recovery was relatively good after 26 …

Urban Infrastructure: Transportation, Public Utilities, Waste Management And Pollution Control, A. Bruce Bishop

Civil and Environmental Engineering Faculty Publications

Paris, tube under the channel -- London, satellite spinning above cables on the ocean floor -- New York, concrete ribbons across undulating land -- San Francisco, silver wings soaring across the Pacific -- Tokyo and Seoul. Etched against the sky are the graceful towers of mighty bridges, the broad glass and steel fronts to massive buildings, the tall slender stacks of industries exhaling; and traced on the surface are the intricate patterns of people and their machines; and buried below are the tubes and tunnels, water pipes and power conduits and communication networks along with concrete caissons and piles that …

Introduction To Simulation/Optimization Modeling For Groundwater Containment Remediation And (B) Ramifications Of Applying S/O Modeling To Groundwater Containment Remediation, With Case Study Examples, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

Normal use of a simulation model to develop a groundwater extraction/injection strategy employs the following process: (1) specify management goals, (2) assume a pumping strategy, (3) simulate system response to the pumping strategy, (4) evaluate acceptability of the system responses, (5) repeat steps (2-4) as required. This is a trial and error approach that is unlikely to actually yield the best pumping strategy for complicated problems

Optimal System Design Of In-Situ Bioremediation Using Parallel Recombinative Simulated Annealing, Horng-Jer Shieh, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

We present a simulation/optimization model combining optimization with BIOPLUME II simulation for optimizing in-situ bioremediation system design. In-situ bioremediation of contaminated groundwater has become widely accepted because of its cost-effective ability to achieve satisfactory cleanup. We use parallel recombinative simulated annealing to search for an optimal design and apply the BIOPLUME II model to simulate aquifer hydraulics and bioremediation. Parallel recombinative simulated annealing is a general-purpose optimization approach that has the good convergence of simulated annealing and the efficient parallelization of a genetic algorithm. This is the first time that parallel recombinative simulated annealing has been applied to groundwater management. …

Optimal In-Situ Bioremediation System Design Using Parallel Recombinative Simulated Annealing, Horng-Jer Shieh, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

Presented is a simulation/optimization (S/0) model combining optimization with BIOPLUME II simulation for optimizing in-situ bioremediation system design. The (S/0) model uses parallel recombinative simulated annealing to search for an optimal design and applies the BIOPLUME II model to simulate aquifer hydraulics and bioremediation. Parallel recombinative simulated annealing is a general-purpose optimization approach that has the good convergence of simulated annealing and the efficient parallelization of a genetic algorithm. We propose a two-stage management approach. The first stage design goal is to minimize total system cost (pumping/treatment, well installation and facility capital costs). The second stage design goal is to …

Preliminary Evaluation Of The Effects Of A Pumping Well On Existing Surface Water Resources Located In T. 12n, R. 2e, Sec. 23, Cache And Box Elder Counties, Denny J. Johnson, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

This report contains the results of a preliminary study of the impact of pumping a well located in T. 12N, R. 2E, sec. 23, Cache and Box Elder Counties, Utah. A semianalytical capture zone analysis was performed to determine if pumping at the well is likely to reduce flow in Willow Creek or any of three springs in the surrounding area. The well has been used from 1974 to present and is sometimes pumped at 90 gallons per minute (gpm) (verbal communication, Veibell, 1996).

On Hack's Law, Riccardo Rigon, Ignacio Rodriguez-Iturbe, Amos Maritan, Achille Giacometti, David G. Tarboton, Andrea Rinaldo

Civil and Environmental Engineering Faculty Publications

Hack's law is reviewed, emphasizing its implications for the elongation of river basins as well as its connections with their fractal characteristics. The relation between Hack's law and the internal structure of river basins is investigated experimentally through digital elevation models. It is found that Hack's exponent, elongation, and some relevant fractal characters are closely related. The self-affine character of basin boundaries is shown to be connected to the power law decay of the probability of total contributing areas at any link and to Hack's law. An explanation for Hack's law is derived from scaling arguments. From the results we …

Software For Optimizing Groundwater Or Conjunctive Water Management, Richard C. Peralta, Alaa H. Aly

Civil and Environmental Engineering Faculty Publications

US/REMAX is a computer program designed to assist water managers in developing optimal groundwater and/or surface water strategies for a wide range of management problems. It employs response matrix, regression and other methods adapted for nonlinear systems. US/REMAX performs deterministic or reliability-based, single- or multi-objective optimization. Decision variables are ground-water extraction/injection and/or surface water diversion. State variables include water flows, stages and concentrations. Hard coded objective functions and constraints are linear, nonlinear, integer or mixed integer. Special constraints can be added to address unusual situations.

Optimization Of Torquer Coil Design For Use With The Small Satellite Attitude Control Simulator, David Deloyd Anderson

Undergraduate Honors Capstone Projects

This paper presents a procedure used to optimize the performance of a ferromagnetic core magnetic torquer coil design for use on the Space Dynamics Laboratory (Logan, UT) Small Satellite Attitude Control Simulator. The items of optimization include the primary goal of maximizing the coil 's magnetic moment while reducing power consumption and system mass within given power, mass, and dimensional constraints. The optimization process makes use of several simple equations to determine a few starting points for design, after which an iterative approach based on experimentation is used to produce the final design. It is found that optimal magnetic moment …

A Spatially-Distributed Hydrologic Model For A Small Arid Mountain Watershed, Thomas H. Jackson, David G. Tarboton, Keith R. Cooley

Civil and Environmental Engineering Faculty Publications

A distributed water balance model was developed as a part of an intensive-field study to simulate the snowmelt-driven hydrologic response of a small mountain watershed using measured values of solar radiation, wind speed, air temperature, relative humidity and precipitation as input.

Snowmelt and evapotranspiration were modeled with point energy balances, written in terms of the snow surface and soil surface temperatures, respectively, corrected for local topographic characteristics and snow drifting. Meltwater was routed to the basin outlet as topography-driven, saturated subsurface flow, with all flow in excess of local transmissivity taken as surface runoff.

The model was calibrated with 1985-6 …

Toward A Balanced Strategy To Address Contaminated Groundwater Plumes At The Massachusetts Military Reservation, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

This document contains the findings and recommendations of the Technical Review and Evaluation Team (TRET) for the plume containment project at the Massachusetts Military Reservation (MMR). The findings and recommendations are in response to the 60 Percent Plume Containment Design, submitted by Operational Technologies (OpTech) in January 1996. In short, the TRET recommends the MMR depart substantially from the strategy of simultaneous, 100 percent containment and treatment that was assigned to OpTech for design in accordance with the Record of Decision (ROD) for Interim Action. This strategy guided the course of the plume containment project over the past two years

Discharge Coefficient Scale Effects Analysis For Weirs, Michael Clyde Johnson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Much work has been published regarding discharge coefficients for various weir structures. What has not been published to the same extent are the effects of model scale associated with the weirs being studied. If laboratory weirs are too small, scale effects can affect the magnitude of the discharge coefficient. These errors may be significant if the weir serves as a control structure for an emergency spillway. It is imperative that discharge be accurately predicted to enable safe design and operation.

Numerical and physical means were employed to analyze the effects of scale associated with Froude Modeling of weirs with sharp …

A Nonparametric Wet/Dry Spell Model For Resampling Daily Precipitation, Upmanu L. Lall, Balaji Rajagopalan, David G. Tarboton

Civil and Environmental Engineering Faculty Publications

A nonparametric wet/dry spell model is developed for resampling daily precipitation at a site. The model considers alternating sequences of wet and dry days in a given season of the year. All marginal, joint, and conditional probability densities of interest (e.g., dry spell length, wet spell length, precipitation amount, and wet spell length given prior to dry spell length) are estimated nonparametrically using at-site data and kernel probability density estimators. Procedures for the disaggregation of wet spell precipitation into daily precipitation and for the generation of synthetic sequences are proffered. An application of the model for generating synthetic precipitation traces …

Effect Of Subsurface Heterogeneity On Free-Product Recovery From Unconfined Aquifers, Jagath J. Kaluarachchi

Civil and Environmental Engineering Faculty Publications

Free-product record system designs for light-hydrocarbon-contaminated sites were investigated to evaluate the effects of subsurface heterogeneity using a vertically integrated three-phase flow model. The input stochastic variable of the areal flow analysis was the log-intrinsic permeability and it was generated using the Turning Band method. The results of a series of hypothetical field-scale simulations showed that subsurface heterogeneity has a substantial effect on free-product recovery predictions. As the heterogeneity increased, the recoverable oil volume decreased and the residual trapped oil volume increased. As the subsurface anisotropy increased, these effects together with free- and total-oil contaminated areas were further enhanced. The …

Optimal Pumping Strategies To Maximize Dissolved Tce Extraction At Mather Afb, California, Richard C. Peralta, Alaa H. Aly

Civil and Environmental Engineering Faculty Publications

USU first estimated the future TCE concentrations that would result if no pumping strategy were implemented (Figure 5, Scenario AO). Then USU used the procedure of Appendix B with the model formulation of Appendix C to compute optimal pumping strategies. In computing optimal strategies USU cycled until an arbitrary three percent contaminant mass convergence criterion was satisfied.

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 …

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 …

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, …

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.

Application Of Confocal Laser Scanning Microscopy To Cytocompatibility Testing Of Potential Orthopaedic Materials In Immortalised Osteoblast-Like Cell Lines, R. Macnair, R. Wilkinson, C. Macdonald, I. Goldie, D. B. Jones, M. H. Grant

Cells and Materials

Confocal laser scanning microscopy (CLSM) was used in conjunction with in vitro cell culture to investigate cellular interactions with orthopaedic biomaterials. Transfected rat and human osteoblasts were seeded on two potential isoelastic hip prosthesis materials, carbon fibre reinforced polyetheretherketone (PEEK) and epoxy. Titanium 318 alloy was employed as a control. Determination of the material surface contour, an important factor influencing cellular adhesion, proliferation and function, was performed using the industry standard Talysurf® and compared to analogous results obtained using the CLSM. The latter technique consistently gave higher values of material roughness but offers the advantage that it can be used …

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 …

A Microstructural Investigation Of Calcium Hydroxyapatites Synthesized From Cahpo4•2h2o And Ca4(Po4)2o, Kevor S. Tenhuisen, Boyd A. Clark, Maria Klimkiewicz, Paul W. Brown

Cells and Materials

This investigation determined the effects of reaction temperature and bulk composition on the microstructural features of hydroxyapatites (HAp) synthesized from reaction between particulate CaHPO₄·2H₂O and Ca₄(PO₄)₂O. These data were used in combination with previous work to further elucidate the mechanistic reaction path taken by these calcium phosphate cements. HAps having two different compositions (Ca/P = 1.50 and 1.67) were synthesized between 15.0 and 70.0°C. All reactions reached completion as indicated by X-ray diffraction. Single point nitrogen absorption was performed on all samples to determine specific surface areas. The HAp which …

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 …

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 …