Engineering Commons^™

Development Of A Rotation Device For Microvascular Endothelial Cell Seeding, G. Pasquinelli, P. Preda, M. Vici, G. N. Martinelli, A. Freyrie, T. Curti, M. D'Addato

Cells and Materials

A rotation device (RD) specifically designed to achieve sterile endothelial cell (EC) seeding of vascular grafts has been developed. The basic characteristics of the RD include: small dimensions, fully autoclavable components, and perfectly sealed graft holders. These features make it possible to maintain sterility during all the steps of EC seeding. This was documented by negativity of all bacteriological assays performed . Moreover, the RD can simultaneously support three vascular grafts with different lengths (20, 40, and 60 cm) and diameters (4-8 mm). EC seeding is performed in the climatized chamber (37 °C; 5 % C02) with constant rotation (0.1 …

The Tissue Responses To Tricalcium Phosphate Ceramics In Bone And Marrow, R. S. Archer, S. Downes, M. V. Kayser, S. Y. Ali

Cells and Materials

Calcium phosphate ceramics are described as "bioactive". Evidence of biological activity associated with calcium phosphate implanted in bone and marrow can be seen as changes in the morphology of the interfaces. In this in vivo model the sequence of progressive bone growth and bone merger with a dense calcium phosphate ceramics were examined by light and transmission electron microscopy. A spectrum of tissue responses to dense tricalcium phosphate ceramics was observed at intervals over a six week period. It is now well established that calcium phosphate ceramics permit bone ingrowth with little or no immunological response; however, a layer of …

Fine Structure Of Remodeling Sites On Iliac Cancellous Bone In Senile Osteoporosis: A Study By Scanning Electron Microscopy Using An Improved Organic Specimen Preparation Method, Toshihiko Takita, Tomonori Naguro, Kichizo Yamamoto

Cells and Materials

We improved on the organic specimen preparation method in order to investigate the details of the functional state of bone in osteoporosis at high magnification level. The usefulness and possibilities of this method are discussed showing fine structural images of remodeling sites. Iliac bones of senile osteoporotic patients obtained by transilial biopsies were studied by scanning electron microscopy (SEM) using the improved preparation method. Excepting the region near the corticoendosteal surface, most of the iliac cancellous bone was composed of thin rod-shaped trabeculae. Remodeling sites on trabeculae appeared as concavities of various sizes and were easily distinguished from inert surfaces. …

Effect Of Surface Treatments On Dentin Bonding Shear Strength, James L. Drummond, D. Racean, J. Van Scoyoc, A. Steinberg

Cells and Materials

The purpose of this study was to determine whether four different treatments on wet or dry teeth, on the buccal and occlusal surfaces, affected the shear bond strength. The surface treatments consisted of a dentin conditioner (pH = 4.0), 10% phosphoric acid (pH = 1.6), 2.5 % nitric acid (pH = 1.0), and 2.5 % citric acid (pH = 1.0). One dentin bonding system and one dental composite was used for all of the specimens. The teeth were mounted in acrylic, ground and etched with the appropriate agent for 15 seconds. The dentin adhesive and composite were applied and the …

Changes In Intracellular Ca2+ And Structure In Platelets Contacting Synthetic Substrates, L. M. Waples, O. E. Olorundare, S. L. Goodman, R. M. Albrecht

Cells and Materials

Platelet structural changes such as spreading and cytoskeletal reorganization that occur upon contact with synthetic surfaces have been well documented . Structural changes such as spreading will vary depending on the substrate involved . Although platelet structural changes following adhesion have been recorded , the cellular mechanisms including changes in intracellular calcium flux underlying these platelet responses are less well understood. In this study, video microscopy was used to image platelet adhesion and spreading while simultaneously imaging intracellular free Ca2+ levels in individual Fura-2 loaded human platelets. This was accomplished using fluorescence video microscopy coupled with video enhanced asymmetric illumination …

Clinical Applications Of Recombinant Gene Technology: Bone And Cartilage Repair, Thomas A. Einhorn

Cells and Materials

Over the past decade, the field of molecular biology has given rise to the development of the applied discipline of molecular medicine. Based on recent developments using recombinant gene technology, genetic mapping analysis and other investigational tools, the physician and surgeon is now ready to begin using those instruments in the diagnosis and treatment of musculoskeletal disease. This article reviews the history of scientific exploration in recombinant gene technology as it applies to bone and cartilage repair. Clinical cases are presented to show how the fruits of scientific knowledge may be brought to bear on some of the more challenging …

Patency Of Small Caliber, Superhydrophobic E-Ptfe Vascular Grafts; A Pilot Study In The Rabbit Carotid Artery, J. M. Schakenraad, I. Stokroos, H. Bartels, H. J. Busscher

Cells and Materials

e-PTFE vascular grafts (Gore, internal diameter 1.5 mm, pore size 30 μm) were luminally treated by ionbeam etching followed by oxygen glow-discharge, to obtain a superhydrophobic luminal surface. Water contact angles of thus modified sheet material were 140-150°, which is significantly higher than on non-treated sheet PTFE (109°). These modified vascular grafts were implanted in the rabbit carotid artery, using an end to end anastomotic technique. After two hours, the grafts were still patent and the wounds were closed. One week after the implantation, the prostheses were still patent. Subsequently, the grafts were harvested and prepared for light microscopy, transmission …

Reactogenicity Of Biomaterials As Studied By Biochemical, Morphological And Ultrastructural Techniques, Leonid I. Slutskii, Natalya A. Sevastjanova, Ivetta L. Ozolanta, Irina V. Kuzmina, Laimdota E. Dombrovska

Cells and Materials

Reactogenicity is a characteristic of biocompatible materials that provokes the reparative and proliferative reaction of connective tissues, a compulsory stage of which is inflammation. Thus, reactogenicity studies should include experiments in vivo. A quantitative assessment of reactogenicity can be obtained by subcutaneous implantation of standard olive-shaped specimens covered by the biomaterial under study followed by biochemical, histological and scanning electron microscopical studies of the capsule developing around the implant. Reactogenicity of surgical threads is evaluated by semiquantitative histological analysis of the wound healing process after suture application. Biomaterial reactogenicity can be modified by changing the structure of the surface and …

Projection Effect Errors In Biomaterials And Bone Research, K. N. Bachus, R. D. Bloebaum

Cells and Materials

Micoradiography and backscattered electron (BSE) imaging are techniques used to investigate the morphologic, histometric, and mineral content changes at the bone/biomaterials interface. Investigators have shown that the superimposition of multiple tissue layers can cause errors with both the morphologic observations and the histometric measurements of bone. The objective of this study was to document errors in the bone mineral content measurements associated with overlapping tissues.

Using a digital image analysis system, microradiographic and BSE images from canine cortical and cancellous bone were captured and analyzed. The results of this study showed that microradiography had more projection effect errors associated with …

Scanning Electron Microscopy Study Of Biofilms On Silicone Voice Prosthesis, T. R. Neu, F. Dijk, G. J. Verkerke, H. C. Van Der Mei, H. J. Busscher

Cells and Materials

Patients after laryngectomy often receive silicone made voice prostheses fot speech rehabilitation. The prosthesis is inserted in a shunt between the trachea and the digestive tract. As the prosthesis is placed in a nonsterile environment it becomes rapidly colonized by microorganisms eventually leading to failure and frequent exchange of the implant. In this study, explanted "Groningen Button" silicone voice prostheses were used to investigate by scanning electron microscopy the biofilm developing on the implant. Two main types of microbial colonization forms could be distinguished. Firstly, macroscopically visible, single colonies dominating on the esophagus side of the prosthesis were found, which …

Apatite - Cholesterol Agglomerates In Human Atherosclerotic Lesions, Sara Sarig, Danielle Hirsch, Reuven Azoury, Teddy A. Weiss, Iony Katz, Howard S. Kruth

Cells and Materials

The purpose of this study was to examine the ultrastructural relationships of cholesterol crystals and apatite deposits in human atherosclerotic lesions. Segments of human aortic atherosclerotic lesions were obtained at autopsy , fixed in glutaraldehyde and dehydrated without using any organic solvents. The aortic segments were coated with carbon and subjected to various scanning electron microscope analyses. These included secondary electron imaging, back scattering of primary electrons, energy dispersive X-ray analysis of selected spots followed by area mapping of calcium and phosphorus , and cathodoluminescence.

The information gathered from scanning of selected areas in the lesions by all the techniques …

Review: Biomaterials For Abdominal Wall Reconstruction, Roger K. J. Simmermacher, Robert P. Bleichrodt, Jeff M. Schakenraad

Cells and Materials

The reconstruction of large abdominal wall defects still is a major surgical problem. Many different techniques have been developed for this purpose, most of which appeared to be unsatisfactory. The lack of sufficient tissue requires the insertion of prosthetic material. Non-absorbable prostheses used to reconstruct abdominal wall defects showed the best results . Polypropylene mesh (PPM) and expanded polytetrafluoroethylene (ePTFE) soft-tissue patch are the most frequently used materials for this purpose . However, PPM induces extensive visceral adhesions and erosion of the skin, whereas ePTFE is insufficiently anchored to the adjacent tissue and therefore both materials are not ideal. As …

Photonics In Switching, Harvard S. Hinton

Electrical and Computer Engineering Faculty Publications

One of the keys to the future of telecommunications companies will be their ability to provide new broadband services to both the business community and residential customers. With the new services will come the need for the equivalent of a broadband switching office. Such a system could require the capability of supporting in excess of 10000 users with broadband channel bit rates exceeding 100 Mb/s. This implies a switching fabric the aggregate bit rate of which could be greater than 1 Tb/s. Guided-wave technology and free-space technology switching fabrics are discussed. Three time-division-based switching fabrics are proposed, and two wavelength-division-based …

Switching To Photonics, Harvard S. Hinton

Electrical and Computer Engineering Faculty Publications

The use of hardware that exploits the interplay of photons and electrons to switch voice, data, and video is discussed. The two directions being taken by current research-guided-wave and free-space photonics-are examined. Photonic time-slot interchanges are described. Multidivisional fabrics, based on a combination of space-division and time-division multiplexing, are considered, as is the wavelength-division-based photonic packet switch, another kind of multidimensional fabric. The use of self-electrooptic effect devices, (SEEDs) is discussed.

Investigation On The Collagen Fiber Network In Human Dental Tissues - Transmission And Scanning Electron Microscopy, C. Marchetti, P. Menghini, C. Piacentini

Cells and Materials

The collagen fiber component of pulp, dentine and cementum, has been studied by isolating it from the inorganic component and the organic non-collagen matrix. This study was carried out on healthy molar and premolar adult teeth. Following demineralization all of the non-collagenous components of the tooth were removed by sequential treatment with H202, with different concentrations of trypsin and with EDTA. The transmission (TEM) and scanning (SEM) electron microscopy investigation confirmed that such a technique is an accurate method for isolating the collagen fibers while preserving their position and their ultrastructure in the dental tissue. The use of TEM and …

Scanning Electron Microscope Observation Of Lubricious Polymer Surface For Medical Use, Hiroyuki Inoue, Yoshikimi Uyama, Emiko Uchida, Yoshito Ikada

Cells and Materials

A peculiar textured structure was found by scanning electron microscopic (SEM) observation on polymer films surface-grafted with water-soluble polyacrylamide and poly(N,N-dimethylacrylamide) after exposure to ozone. The grafted surface became very hydrophilic and highly lubricated when brought into contact with water, due to hydration of the grafted surface layer. Unless water was present, the surface did not become slippery at all. SEM of the grafted surface revealed different profiles, depending on the graft density as well as the process of drying prior to the SEM observation. There was no significant difference between the virgin and the surface-grafted film, when air-dried under …

Interaction Of Liposomal Drug Delivery Systems With Cells And Tissues: Microscopic Studies, M. Foldvari, G. T. Faulkner, C. Mezei, M. Mezei

Cells and Materials

Liposomes , as drug carriers, can be administered into the body by several routes e.g. intravenously, intraperitoneally, intramuscularly, intratracheally and topically among others. Radiolabelled markers are suitable to monitor the distribution and elimination of liposomes, but the tissue deposition of intact liposomes, the mode and sites of drug release from the liposomes and liposome-cell interactions cannot be investigated morphologically. Microscopic techniques could provide information regarding the intact state of liposomes and possibly the dynamics of liposomes in tissues provided that they can be identified with certainty in vivo. This is a formidable problem and in spite of several attempts, there …

Evaluation Of Bacterial Glycocalyx Preservation And Staining By Ruthenium Red, Ruthenium Red-Lysine And Alcian Blue For Several Methanotroph And Staphylococcal Species, Theresa A. Fassel, James E. Van Over, Christopher C. Hauser, Lorie E. Buchholz, Charles E. Edmiston, James R. Sanger, Charles C. Remsen

Cells and Materials

The cationic reagents, ruthenium red (RR), alcian blue (AB) and ruthenium red -lysine were compared for ultrastructural preservation and staining of the bacterial glycocalyx. En bloc RR, AB and RR-lysine procedures, and a glutaraldehyde/OsO4 fixation withou t cationic reagent, were evaluated by transmission electron microscopy (TEM) for several methanotroph and staphylococcal species. The glutaraldehyde/OsO4 fixation was totally ineffective in preserving or staining the glycocalyx material in all species studied. The RR procedure was more effective than the glutaraldehyde/OsO4 fixation but was generally less so than the RR-lysine procedure. By the RR-lysine procedure, extensive layers that were often filamentous or fibrous …

Evaluation Of Mechanisms Of Alteration And Humification Of Pahs For Water Quality Management, Ronald C. Sims, Carolyn K. Abbott

Reports

Introduction: Creosote-pentachlorophenol (PCP) is a mixture commonly used as a wood preservative in the U.S. (1). A 1988 survey (2) indicated that 1,397 wood preserving waste contaminated sites exist in the United States consisting of 555 active wood treatment plants and 842 inactive plants. Stinson (3) indentifed 58 wood preserving sites on the National Priorities List, of which 51 have PCP and/or creosote or polycyclic aromatic hydrocarbon (PAH) contamination. Principal classes of organic constituents present in creosote waste are PAHs (~85% by weight) and phenolics. PAHs with less than three fused benzene rings comprise 69% (i.e., naphthalene, anthracene and phenanthrene); …

Bioengineering For Water Cleanup: State-Of-The-Art Assessment, Judith L. Sims, Ronald C. Sims, Jon S. Ginn

Reports

No abstract provided.

A Spatially Distributed Water Balance Based On Physical, Isotropic And Airborne Remotely Sensed Data, C. M.U. Neale, David G. Tarboton, J. J. Mcdonnell

Reports

Introduction: The objective of this research to develop a spatially distributed water balance model based on the integration of spatially distributed data. Progress this year has consisted of model development, instrument acquisition, installation and development of experimental procedures, and baseline data collection. The original research plan called for detailed observations related to the water balance over the year September 1991 to August 1992. The detailed measurements were to start with accumulation of the snowpack followed by melt and evapotranspiration measurements from March to August. The objective was to measure the energy balance parameters starting with the peak accumulation, through the …

Nonparametric Stratigraphic Interpretation From Drill Log Data, Upmanu Lall, A. I. Ali

Reports

Near surface groundwater contamination is a widespread problem. The potential for contamination of deep aquifers in such areas depends on the vertical hydraulic gradient as well as the extent and location of interconnection between the upper and lower aquifers. In alluvial, sedimentary environment, the geologic units are typically weakly connected lenses or layers of high or low conductivity with variable size, geometry and orientation. Drill logs provide qualitative, local information on such aquifer heterogeneities. A binary (high or low conductivity) indicator function is used to describe the aquifer system. A nonparametric statistical methodology for assessing the probability that a particular …

Composting Of Explosives Contaminated Soil Using The White Rot Fungus Phanerochaete Chrysosporium, Michael J. Mcfarland, Shashi Kalaskar, Eric Baiden

Reports

Bioaugmentation using the white rot fungus Phanerochaete chrysosporium was found to be effective in enhancing TNT removal in lightly (i.e., below 100 mg/kg) contaminated soil. The percent reduction in TNT increased from 15% to 53% when soils were treated with fungal inoculated organic material. Maximum removal rates improved from 0.33 mg TNT/kg-day to 0.76 mg TNT/kg-day during the same treatment. Neither fungal inoculation nor organic amendment addition resulted in improving TNT removal kinetics in highly contaminated soils (i.e., above 1000 mg/kg). Executive Summary: Laboratory scale compost studies were conducted to evaluate the effect of bioaugmentation with the white rot fungus,

Maximizing Sustainable Ground-Water Withdrawals: Comparing Accuracy And Computational Requirements For Steady-State And Transient Digital Modeling Approaches, Richard C. Peralta, R. R.A. Cantiller, Gary L. Mahon

Civil and Environmental Engineering Faculty Publications

Rigorous models for maximizing sustainable groundwater withdrawals may require more computer memory for their constraint set than is available. In some situations, alternative constraint formulations yield similar or identical answers resulting in great saving in computer memory requirements. In order to evaluate the efficiency of using alternative constraints1 maximum ground-water withdrawal pumping strategies were computed by three digital models for a hypothetical area for a five-decade period. Model A maximized steady ground-water withdrawal. Model B maximized unsteady ground-water mining. Model C maximized unsteady ground-water mining subject to a constraint that final pumping be sustainable after the end of the 50-year …

Optimal Linear/Nonlinear, Quantity/Quality Management Of Complex Multilayer Aquifers By Embedding, Ali Gharbi, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

The embedding optimization modelling approach is adapted to aid long-term groundwater quality and quantity management of complex nonlinear multilayer aquifers. Implicit block-centered finite-difference approximations of the quasi-three-dimensional unsteady flow equation, and Galerkin finite-element approximations of the twodimensional advection-dispersion transport equation are embedded as constraints in the model. Other hydrological processes are also included as constraints. Cyclical linear differencing permits representation of nonlinear transport, even when contaminant is extracted by unsteady pumping (a decision variable). Also used are nonlinear (discontinuous derivative) constraints describing drainage, stream-aquifer interflow and evapotranspiration. The use of both linear and nonlinear formulations of the entire flow and …

Fate And Transport Of Tce-Petroleum Hydrocarbon Mixture At Uttr, G. Nash Quashiga, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

In 1988 a preliminary assessment (PA) study was conducted at Chemical Disposal Pit No. 4 to address several concerns of Hill Air Force Base (HAFB), the facility operators. The objectives of the PA were; i) to assess the potential for organic chemical releases to the subsurface environment, and ii) to determine the need for any immediate control measures, if the subsurface environment were threatened.

Optimizing Perennial Groundwater Yield Planning For Nonlinear Systems: Approach Comparison, Shu Takahashi, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

Four alternative simulation/optimization models useful for computing optimal sustained-yield (steady-state) groundwater pumping strategies are compared in terms of formulation, solution procedure, accuracy, and computational efficiency. The different models require different computer processing time and memory. For the aquifer tested system, if more than 10% of the cells have pumping as a decision variable, a fully linearized embedding model will require less computer memory than any other model. All the models address linear and nonlinear steady-state flow in multilayer, unconfined/confined aquifers. They also address several types of nonsmooth external flows. Newly presented are a response matrix model solving external flows described …

Optimizing Ground Water Planning And Management, Richard C. Peralta, L. S. Willardson

Civil and Environmental Engineering Faculty Publications

Simulation/optimization (S/0) models can be used to speed the process of computing long term groundwater pumping strategies. These combined models can also greatly ease the planning tasks of water management agencies. They make the process of computing optimal perennial yield groundwater management strategies fairly straightforward. S/0 models dramatically improve conjunctive water management and can help minimize the cost of groundwater contaminant clean-up. The differences between S/0 models and the simulation (S) models currently used by over 98 % of practitioners are illustrated with recent applications of S/0 models in regional planning.

Best Management Practices (Bmps) To Minimize Nitrate Leaching From Irrigated Potatoes, Ahmad Yar Ranjha, Richard C. Peralta, Robert W. Hill

Civil and Environmental Engineering Faculty Publications

Numerous preliminary simulations are again performed to determine the smallest fertilizer amount, applied througii sprinkler irrigations (chemigation), that should still yield 15.3 tons of potatoes per acre. Applying only 68 lbs/ac of ammonium nitrate fertilizer in the first irrigation on June 28, should be sufficient. Again, total crop N uptake equals potential crop N uptake throughout the growing season. Except for the net income and applied fertilizer N uptake efficiency, all the other results computed by NLEAP (Figure 4 and Table 1) are very similar to results of scenario II. Applied fertilizer N uptake efficiency is the highest (91%) in …

Optimal Groundwater Quantity/Quality Planning For Salt Lake Valley, Ali Gharbi, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

Generally, the embedding technique for optimizing groundwater management has been limited to small scale or steady-state groundwater flow management cases. The embedding approach causes sparse, highly structured constraint matrices which have been sometimes difficult to solve. Embedding applications have been limited by lack of: optimization algorithms able to easily address such matrices for large scale problems, and efficient methods for addressing common nonlinearities and converging to a solution. Computer software, USUEM, addresses these issues by: creation of alternative linear, nonlinear, combined and partitioned formulations of the same problem, implemention of an efficient cycling procedure, and good selection of optimization algorithm …