Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Utah State University

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 4471 - 4500 of 5443

Full-Text Articles in Engineering

Us/Remax (Vs 2.70): Software For Optimizing Management Of Stream/Aquifer Systems Using The Response Matrix And Related Methods, Richard C. Peralta, Alaa H. Aly Apr 1995

Us/Remax (Vs 2.70): Software For Optimizing Management Of Stream/Aquifer Systems Using The Response Matrix And Related Methods, Richard C. Peralta, Alaa H. Aly

Civil and Environmental Engineering Faculty Publications

US/REMAX is designed to assist water managers in developing optimal groundwater and/or surface water strategies for a wide range of management problems. US/REMAX uses the response matrix method, which assumes that physical system response to stimuli is linear. However, US/REMAX can also address nonlinear systems via cycling. In one application, a strategy computed using US/REMAX required 40% less pumping than one obtained via a normal simulation model. US/REMAX also easily computes tradeoffs for multiobjective problems.

Go to article

Modeling For Optimal Management Of Agricultural And Domestic Wastewater Loading To Streams, Muhammad Shafqat Ejaz, Richard C. Peralta Apr 1995

Modeling For Optimal Management Of Agricultural And Domestic Wastewater Loading To Streams, Muhammad Shafqat Ejaz, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

A simulation/optimization (S/0) model to aid managing multiobjective wastewater loading to streams while maintaining adequate downstream water quality is presented. The conflicting objectives are to maximize the human and dairy cattle populations from which treated wastewater can be discharged to the river system. Nonindustrial municipal (domestic) wastewater undergoes primary and secondary treatment by a sewage treatment plant (STP) before entering as a steady point source. Dairy wastewater is treated by overland flow (OLF) land treatment before entering the stream as a controlled steady diffuse source. Maximum dual-source loading strategies which do not degrade downstream water quality beyond specified limits are …

Go to article

Proceedings Of The 1995 Annual Symposium On Engineering Geology And Geotechnical Engineering (No. 31), Joseph A. Caliendo Mar 1995

Proceedings Of The 1995 Annual Symposium On Engineering Geology And Geotechnical Engineering (No. 31), Joseph A. Caliendo

Reports

No abstract provided.

Go to article

Assuring A Long Term Groundwater Supply: Issues, Goals And Tools, Richard C. Peralta Mar 1995

Assuring A Long Term Groundwater Supply: Issues, Goals And Tools, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

Groundwater is a hidden, but important resource. We can practicably define groundwater as water beneath the ground surface that can be extracted by wells. Other water in the ground that is not considered to be available for man’s direct use is commonly called “subsurface water.” Subsurface water includes moisture within the root zone.

Go to article

In Vitro Characterization Of Transforming Growth Factor-Ss1-Loaded Composites Of Biodegradable Polymer And Mesenchymal Cells, S. B. Nicoll, A. E. Denker, R. S. Tuan Jan 1995

In Vitro Characterization Of Transforming Growth Factor-Ss1-Loaded Composites Of Biodegradable Polymer And Mesenchymal Cells, S. B. Nicoll, A. E. Denker, R. S. Tuan

Cells and Materials

A porous, biodegradable polymer composite was fabricated from poly(L-lactic acid) (PLLA) using a solvent- casting particulate-leaching technique, and loaded with recombinant human transforming growth factor ß-1 (TGF-ß1). Tissue culture polystyrene (TCPS) and PLLA disks loaded with bovine serum albumin (BSA) served as controls. Polymer specimens were seeded at high cell density with C3H10T1/2 cells, a mouse embryonic cell line capable of differentiating into various connective tissue cell types. The polymer matrices degraded slowly in physiological saline over four weeks, with a sustained yet sporadic release of active TGF-ß1; a more controlled release of TGF-ß1 was observed in serum-containing culture medium …

Go to article

Post-Operative Carbonate-Apatite Formation In Peo/Pbt Copolymers (Polyactive®), A. M. Radder, J. E. Davies, R. N. S. Sodhi, S. A. T. Van Der Meer, J. G. C. Wolke, C. A. Van Blitterswijk Jan 1995

Post-Operative Carbonate-Apatite Formation In Peo/Pbt Copolymers (Polyactive®), A. M. Radder, J. E. Davies, R. N. S. Sodhi, S. A. T. Van Der Meer, J. G. C. Wolke, C. A. Van Blitterswijk

Cells and Materials

Previous studies have stressed the importance of calcification of the polyethylene oxide (PEO) I polybutylene terephthalate (PBT) copolymer surface by establishing a direct relation with the occurrence of bone-bonding. Here, we characterized the morphology as well as the composition of this post-operative reaction product in PEOIPBT copolymers. X-ray · photoelectron spectroscopical results demonstrated the ability of PEOIPBT copolymers to rapidly adsorb calcium ions from fluids. After subcutaneous implantation in rats, it was shown that polymer calcification comprised plate-shaped crystals, whereas an electron-dense layer was frequently encountered at the interface. Cells with a characteristic morphology were directly apposed to abundantly calcified …

Go to article

Hip Prosthesis And Bone Mineral Absorptiometry: Effect Of Short-Term Administration Of Calcitriol, Mario Caniggia, Bruno Frediani, Leonardo Osti Jan 1995

Hip Prosthesis And Bone Mineral Absorptiometry: Effect Of Short-Term Administration Of Calcitriol, Mario Caniggia, Bruno Frediani, Leonardo Osti

Cells and Materials

In this double blind study, seven out of fourteen patients who had received a cementless hydroxyapatitecovered hip prosthesis were given calcitriol (1 p.g daily), and seven an inert placebo for a period of four months. At the end of this period, total body bone densitometry (TBBD) and absorptiometric measurements in the regions of interest (ROIs) close to the prosthesis and in the opposite femur revealed that the TBBD values had decreased in the patients receiving placebo and increased in those receiving calcitriol. Furthermore, bone mineral density in the ROis had increased on the non-operated side of the calcitriol-treated patients (although …

Go to article

Backscattered Electron Imaging To Enhance Microstructural Contrast In Poly(Methyl Methacrylate) Bone Cement Fracture Analysis, L. D. T. Topoleski, P. Rutledge, X. Lu Jan 1995

Backscattered Electron Imaging To Enhance Microstructural Contrast In Poly(Methyl Methacrylate) Bone Cement Fracture Analysis, L. D. T. Topoleski, P. Rutledge, X. Lu

Cells and Materials

Poly(methyl methacrylate) (PMMA) bone cement is used as a grout to secure joint replacement prostheses into bone. It has a distinct microstructure made up of: prepolymerized beads, an interbead matrix polymer, a radiopacifier {barium sulphate (BaS04) or zirconium dioxide (Zr02)}, and pores or voids; the radiopacifier is found only in the interbead matrix of the cured bone cement. The mechanism of slow or fatigue crack growth appears to be initial micro-cracking through the interbead matrix, followed by coalescence of the microcracks to form a continuous crack. Thus, distinguishing the interbead matrix from the pre-polymerized beads is important for investigating fatigue …

Go to article

Biodegradation Of Synthetic Biphasic Calcium Phosphate And Biological Calcified Substratum By Cells Of Hemopoietic Origin, A. Soueidan, O. I. Gan, J. M. Bouler, F. Gouin, G. Daculsi Jan 1995

Biodegradation Of Synthetic Biphasic Calcium Phosphate And Biological Calcified Substratum By Cells Of Hemopoietic Origin, A. Soueidan, O. I. Gan, J. M. Bouler, F. Gouin, G. Daculsi

Cells and Materials

Different types of osteoclastic cells (authentic osteoclasit from human giant cell tumor and bone marrow of newborn rats; newly-formed osteoclasts from adult rat bone marrow), giant multinucleated cells and macrophages were studied for their effect on synthetic and natural mineralized substrata. Biphasic calcium phosphate ceramic consisted of hydroxyapatite and beta tricalcium phosphate was chosen for in vitro experiments, and dentine served as a positive control for cell resorbing activity . Our results show the limited capacity of authentic and newly-formed osteoclasts to resorb synthetic ceramic as compared to that of natural substrata. In vitro cell-mediated biodegradation included also modifications of …

Go to article

Resorption Of Natural Calcium Carbonate By Avian Osteoclasts In Vitro, G. Guillemin, S. J. Hunter, C. V. Gay Jan 1995

Resorption Of Natural Calcium Carbonate By Avian Osteoclasts In Vitro, G. Guillemin, S. J. Hunter, C. V. Gay

Cells and Materials

Osteoclasts isolated from the endosteum of 2.5 to 3-week chick tibia were cultured on glass coverslips or natural CaC03 (Tridacna) wafers for 2 and 4 days. The cells were exposed to the pH-dependent dye, acridine orange, and fluorescence was measured by a light microscope photometer. Fluorescence intensity values were higher in cells adherent to Tridacna wafers than in those incubated on glass after 2 and 4 days of culture (three and two-fold, respectively). Moreover, osteoclasts on Tridacna wafers were more flattened and were found to produce resorption pits. Acid production by osteoclasts cultured on Tridacna wafers was stimulated …

Go to article

Cell Adhesion To Crystal Surfaces: A Model For Initial Stages In The Attachment Of Cells To Solid Substrates, D. Hanein, B. Geiger, L. Addadi Jan 1995

Cell Adhesion To Crystal Surfaces: A Model For Initial Stages In The Attachment Of Cells To Solid Substrates, D. Hanein, B. Geiger, L. Addadi

Cells and Materials

This study addresses the mechanism of the chirally-restricted, ROD-independent adhesion of A6 epithelial cells to the {011} faces of calcium {R,R)-tartrate tetrahydrate crystals. The extensive and rapid adhesion of the cells to these surfaces, in the presence or absence of serum proteins, is distinctly different from the extracellular matrix-mediated adhesion to conventional tissue culture surfaces or to the {101} faces of the same crystals. The differences are manifested by insensitivity to ATP depletion, to disruption of microfilaments and microtubules and even to formaldehyde fixation of the cells. Furthermore, trypsin pretreatment does not affect cell attachment to the {011} faces, nor …

Go to article

Room Temperature Aging Of Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, Qiang Wu, Alan B. Carr, John C. Mitchell Jan 1995

Room Temperature Aging Of Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, Qiang Wu, Alan B. Carr, John C. Mitchell

Cells and Materials

Specimens of three Pd-Cu-Ga dental alloys cast five years ago and subsequently stored at room temperature were reexamined and observed to have lower amounts of the eutectic constituents in the near-surface region than originally present, along with other microstructural changes. This previously unreported room temperature aging behavior of these alloys is attributed to the presence of high-diffusivity paths in the non-equilibrium ascast eutectic structures and to the essential role of the surface for the vacancy diffusion mechanism. These results may have important clinical significance for the ill vivo corrosion resistance and long-term biocompatibility of the Pd-Cu-Ga alloys.

Go to article

Reliability Of Human Fresh And Frozen Gingiva Explant Culture In Assessing Dental Materials Cytocompatibility, R. Warocquier-Clerout, G. C. Hachom-Nitcheu, M. F. Sigot-Luizard Jan 1995

Reliability Of Human Fresh And Frozen Gingiva Explant Culture In Assessing Dental Materials Cytocompatibility, R. Warocquier-Clerout, G. C. Hachom-Nitcheu, M. F. Sigot-Luizard

Cells and Materials

An explant culture of human gingival epithelium has been set up in order to provide a valuable test for evaluating the cytocompatibility of dental material s. In an attempt to supply a bank of gingiva ex plants, frozen and freshly excised specimens were cultured in parallel. Optical and scanning electron microscopy showed an early release of cuboidal cells forming a dense layer around the explants. Afterwards, cultures evolved differently . Spread cells grew and migrated more rap idly in fresh than in frozen explant cultures but their adhesion to substratum increased earlier in frozen ones. Epithelial phenotype of cells had …

Go to article

Biomaterials Associated Infections: The Scale Of The Problem, David J. Stickler, Robert J. C. Mclean Jan 1995

Biomaterials Associated Infections: The Scale Of The Problem, David J. Stickler, Robert J. C. Mclean

Cells and Materials

The biomaterials used in the manufacture of implanted prosthetic devices profoundly impair the host's ability to opsonise and phagocytose invading microbes. As a result, while these devices generally provide effective relief from painful, crippling and life-threatening disorders, they can also induce vulnerability to infection in the recipients. The surfaces of the implants are susceptible to colonisation by microbial biofilms. The cells in the biofilm.s are further protected against opsonophagocytosis and are also resistant to antibacterials. Device associated infections thus tend to be refractile to antibiotic therapy and in many cases the device has to be removed before the infection will …

Go to article

Biphasic Sodium Fluoride Effects On Bone And Bone Mineral: A Review, P. -T. Cheng, S. M. Bader, M. D. Grynpas Jan 1995

Biphasic Sodium Fluoride Effects On Bone And Bone Mineral: A Review, P. -T. Cheng, S. M. Bader, M. D. Grynpas

Cells and Materials

This paper reviews the clinical and experimental findings on the effects of sodium fluoride (NaF) on human and animal bone. NaF has been shown to cause a significant increase in axial skeletal bone mass. However, there is concern that the new bone may not provide the desired increase in bone strength. Yet, NaF remains the most commonly used agent capable of stimulating bone formation in most patients (30% non-responders). But whether NaF reduces vertebral fracture rate (VFR) remains controversial. For a given treatment duration, the effect of F on bone quality appears to depend on dose: there is a marked …

Go to article

Natural History Of Bone Response To Hydroxyapatite-Coated Hip Prostheses Implanted In Humans, P. Frayssinet, D. Hardy, J. S. Hanker, B. L. Giammara Jan 1995

Natural History Of Bone Response To Hydroxyapatite-Coated Hip Prostheses Implanted In Humans, P. Frayssinet, D. Hardy, J. S. Hanker, B. L. Giammara

Cells and Materials

A series of 15 autopsied femurs containing hydroxyapatite- coated (HA-coated) prostheses was analysed histologically. Their implantation time ranged from 5 days up to 3 years. The coating thickness of some prostheses and the percentage of the coating in contact with bone at different levels were evaluated using an image analysis device. After the newly formed bone tissue had became mature, several bone morphotypes were identified at the coating contact. From the proximal to the distal part of the prosthesis, bone morphotype was denser and the percentage of the coating surface in contact with bone increased. Several stages in the prosthesis …

Go to article

Synthetic Hydrogel As An Artificial Vitreous Body. A One-Year Animal Study Of Its Effects On The Retina, T. V. Chirila, I. J. Constable, Y. Hong, S. Vijayasekaran, M. F. Humphrey, P. D. Dalton, S. G. Tahija, M. A. L. Maley, M. J. H. Cuypers, C. Sharp, S. R. Moore, M. J. Davies Jan 1995

Synthetic Hydrogel As An Artificial Vitreous Body. A One-Year Animal Study Of Its Effects On The Retina, T. V. Chirila, I. J. Constable, Y. Hong, S. Vijayasekaran, M. F. Humphrey, P. D. Dalton, S. G. Tahija, M. A. L. Maley, M. J. H. Cuypers, C. Sharp, S. R. Moore, M. J. Davies

Cells and Materials

A hydrogel with a high water content was assessed in vitro and in vivo as a possible vitreous substitute. From a large series of polymers produced by the aqueous polymerization of methyl acrylamidoglycolate methyl ether (MAGME), a gel synthesized in 80% water was selected for an animal study. The gel was injected intravitreally into rabbit eyes and followed clinically by ophthalmoscopy, tonometry, and fundus photography. The gel was clinically well tolerated, but after 6 months ophthalmoscopy revealed progressive pallor of the optic nerve head. The eyes were enucleated one year after injection of polymer. Histopathological examination by light microscopy of …

Go to article

Three-Dimensional Morphology And Platelet Adhesion On Pyrolytic Carbon Heart Valve Materials, S. L. Goodman, K. S. Tweden, R. M. Albrecht Jan 1995

Three-Dimensional Morphology And Platelet Adhesion On Pyrolytic Carbon Heart Valve Materials, S. L. Goodman, K. S. Tweden, R. M. Albrecht

Cells and Materials

Low-temperature isotropic pyrolytic carbon (LTIC) is the preferred material for mechanical heart valve prosthetics due to its durability and good thromboresistance, although thromboembolic complications remain a significant clinical problem. LTlC morphology has been previously studied using scanning (SEM) and transmission electron microscopy (TEM), and scanning tunneling microscopy (STM). However, these microscopies have limitations with imaging rough surfaces. In this study, LTIC valve leaflets from CarboMedics, Inc. and St. Jude Medical, Inc. were prepared and polished exactly as used in clinical prosthetics, and examined at magnifications up to macromolecular resolution using stereo-pair low-voltage SEM (LV -SEM). LV -SEM reveals that LTIC …

Go to article

An Optical Backplane Demonstrator System Based On Fet-Seed Smart Pixel Arrays And Diffractive Lenslet Arrays, D. V. Plant, B. Robertson, Harvard Scott Hinton, W. M. Robertson, G. C. Boisset, N. H. Kim, Y. S. Liu, M. R. Otazo, D. R. Rolston, A. Z. Shang Jan 1995

An Optical Backplane Demonstrator System Based On Fet-Seed Smart Pixel Arrays And Diffractive Lenslet Arrays, D. V. Plant, B. Robertson, Harvard Scott Hinton, W. M. Robertson, G. C. Boisset, N. H. Kim, Y. S. Liu, M. R. Otazo, D. R. Rolston, A. Z. Shang

Electrical and Computer Engineering Faculty Publications

We have demonstrated a representative portion of an optical backplane using FET-SEED smart pixels and free-space optics to interconnect printed circuit boards (PCB's) in a two board, unidirectional link configuration. 4×4 arrays of FET-SEED transceivers were designed, fabricated, and packaged all the PCB level, The optical interconnection was constructed using diffractive microoptics, and custom optomechanics. The system was operated in two modes, one showing high data throughput, 100 MBit/sec, and the other demonstrating large connection densities, 2222 channel/cm2.

Go to article

Design And Construction Of An Active Alignment Demonstrator For A Free-Space Optical Interconnect, G. C. Boisset, B. Robertson, Harvard Scott Hinton Jan 1995

Design And Construction Of An Active Alignment Demonstrator For A Free-Space Optical Interconnect, G. C. Boisset, B. Robertson, Harvard Scott Hinton

Electrical and Computer Engineering Faculty Publications

An x-y active alignment system based on Risley beam steerers is described. The demonstrator features a quadrant detector which detects the misalignment error between the center of a spot of light and the center of the quadrant detector. This misalignment error is then used by a new algorithm to calculate the rotational displacement required for the two Risley beam steerers to steer the spot of light to the center of the quadrant detector. The experimental results indicate that any spot misaligned by up to 160 μm on the quadrant detector will be systematically centered by the demonstrator system.

Go to article

Scanning Electron Microscopy Studies Of Ceramic Layers And Interfacial Regions For Calcium Phosphate-Coated Titanium Dental Implants, W. A. Brantley, E. Tufecki, J. C. Mitchell, D. W. Foreman, E. A. Mcglumphy Jan 1995

Scanning Electron Microscopy Studies Of Ceramic Layers And Interfacial Regions For Calcium Phosphate-Coated Titanium Dental Implants, W. A. Brantley, E. Tufecki, J. C. Mitchell, D. W. Foreman, E. A. Mcglumphy

Cells and Materials

The surface and cross-section characteristics of the plasma-sprayed calcium phosphate coatings, along with the microstructures and elemental compositions near the titanium alloy interface, were investigated by scanning electron microscopy for two different dental implants of proprietary compositions: Integra!® (Calcitek) and BioVent ® (Dentsply). Elemental concentrations (Ca, P, Ti, AI, and V) near the interfaces were obtained by X-ray energy-dispersive spectroscopy. Coating surfaces exhibited a splat deposition topography of greatly differing microstructural scale for the two implants, along with other features characteristic of the plasma-spraying process; cross-sections of the coatings revealed minimal porosity. Some interdiffusion of principally titanium and calcium was …

Go to article

Co-Culture Of Endothelial Cells And Smooth Muscle Cells In A Flow Environment: An Improved Culture Model Of The Vascular Wall?, Thierry Ziegler, Keith A. Robinson, R. Wayne Alexander, Robert M. Nerem Jan 1995

Co-Culture Of Endothelial Cells And Smooth Muscle Cells In A Flow Environment: An Improved Culture Model Of The Vascular Wall?, Thierry Ziegler, Keith A. Robinson, R. Wayne Alexander, Robert M. Nerem

Cells and Materials

Numerous studies have demonstrated that the neighboring smooth muscle cells (SMC) influence the morphology, cytoskeleton and growth of co-cultured endothelial cells (EC). Also, flow-induced laminar shear stress has been shown to induce cell elongation, F-actin reorganization and growth inhibition in cultured EC. We investigated the effect of neighboring SMC and collagen matrix on the response of EC to shear stress. The co-culture system was made by growing porcine aortic SMC in a gel of collagen type I and then seeding porcine aortic EC (P AEC) on the top surface. Then the co-culture was exposed to steady, laminar shear stress of …

Go to article

Bone Absorptiometry In Metabolic Bone Disease: Baseline Values And Long-Term Treatment With Calcitriol (Post-Menopausal Osteoporosis Versus Osteomalacia), A. Caniggia, B. Frediani Jan 1995

Bone Absorptiometry In Metabolic Bone Disease: Baseline Values And Long-Term Treatment With Calcitriol (Post-Menopausal Osteoporosis Versus Osteomalacia), A. Caniggia, B. Frediani

Cells and Materials

Total body bone absorptiometry reveals low mineral density in both postmenopausal osteoporosis and osteomalacia patients. The method was used to investigate the effect of calcitriol administration on patients suffering from one of these conditions. In osteomalacia, the administration of calcitriol resulted in a dramatic improvement in bone mineral density (sometimes up to 50% in 12 months), indicating the rapid mineralization of previously uncalcified bone tissue as a result of the normalization of the Ca x P product. In osteoporosis a similar treatment was seen to halt the progressive decrease in bone mineral levels and sometimes resulted in minor increases in …

Go to article

Optical Bone Chambers As Tools For Studying The Bone-Implant Interface: A Review, Howard Winet Jan 1995

Optical Bone Chambers As Tools For Studying The Bone-Implant Interface: A Review, Howard Winet

Cells and Materials

Bone chamber intravital microscopy combines the control volume of in vitro models and the chemical complexity of in vivo models to optimize the study of bone physiology in situ. As an optical tool it provides a window to dynamic events at the tissue level of magnification. In particular, it allows measures of microvascular events: (1) in space by magnifying local perfused vasculature and microcirculation at any instant, and (2) in time by providing the same volume of tissue for weekly viewing of an evolving process such as bone healing. This quartz-bearing titanium screw has revealed a consistent order for …

Go to article

A Morphological Assessment Of Bovine Chondrocytes Cultured On Poly(Ethyl Methacrylate)/Tetrahydrofurfuryl Methacrylate, R. M. Sawtell, M. V. Kayser, S. Downes Jan 1995

A Morphological Assessment Of Bovine Chondrocytes Cultured On Poly(Ethyl Methacrylate)/Tetrahydrofurfuryl Methacrylate, R. M. Sawtell, M. V. Kayser, S. Downes

Cells and Materials

A heterocyclic methacrylate polymer system, PEMA/THFMA, has shown potential as a biomaterial for cartilage repair in a rabbit model and has properties making it suitable for use clinically. The ability of the polymer system, PEMA/THFMA, and a related system, PEMA/HEMA, to support chondrocytes in vitro was assessed by scanning electron microscopy. Chondrocytes adhered to the surface of the PEMA/THFMA by day one, having a rounded morphology and clustered appearance opposed to the Thermanox® control, where the cells had spread out and become fibroblastic in appearance. The chondrocytes divided rapidly on the PEMA/ THFMA system by day three and had completely …

Go to article

Adsorption Of Bovine Serum Albumin Onto Octacalcium Phosphate And Its Hydrolyzates, O. Suzuki, H. Yagishita, M. Yamazaki, T. Aoba Jan 1995

Adsorption Of Bovine Serum Albumin Onto Octacalcium Phosphate And Its Hydrolyzates, O. Suzuki, H. Yagishita, M. Yamazaki, T. Aoba

Cells and Materials

Octacalcium phosphate (OCP) has been advocated to be a precursor of biomineral s. Tn this report , we aimed at investigating OCP hydrolysis and the interaction of OCP and its hydrolyzates (apatitic products) with bovine serum albumin (BSA). A batch of synthetic OCP was allowed to hydrolyze either (a) in deionized water at 70°C or (b) in Tris buffer (pH 7.4) containing 2 ppm fluoride at 37°C. OCP hydrolysis was completed within reasonable experimental periods: after 48 hours at 70°C and after 10 days at 37°C in the presence of fluoride. The adsorption isotherms of BSA onto the original OCP …

Go to article

Some Biological And Physical Properties Of Laser Deposited Hydroxyapatite Based Films, Tatjana Dostalova, Lucie Himmlova, Miroslav Jelinek, Jirina Bartova Jan 1995

Some Biological And Physical Properties Of Laser Deposited Hydroxyapatite Based Films, Tatjana Dostalova, Lucie Himmlova, Miroslav Jelinek, Jirina Bartova

Cells and Materials

The preliminary results of biological and physical tests of hydroxyapatite thin films deposited on dental implants by a new technology with the KrF excimer laser ablation method were evaluated. Biological and physical properties were studied and analyzed by the lymphocyte proliferation test and scanning electron microscopy (SEM), X-ray analysis, Rutherford backscattering analysis (RBS) and particle induced X-ray emission (PIXE) methods. Ten bioceramic films from 45 samples had very good physical and biological properties. Creation of hydroxyapatite thin films with laser ablation can have a positive effect on adhesion of the film and protection for corrosion.

Go to article

Adsorption Of Proteins At Solid-Liquid Interfaces, Willem Norde Jan 1995

Adsorption Of Proteins At Solid-Liquid Interfaces, Willem Norde

Cells and Materials

This paper concisely reviews the general principles underlying protein adsorption from aqueous solution onto a solid surface. The discussion includes the various stages of the adsorption process, i. e., transport of the protein molecules towards the surface, the absorbed amount under equilibrium conditions, desorption and re-adsorption. Among the interactions that determine the overall protein adsorption process (1 ) redistribution of charged groups in the interfacial layer, (2) changes in the hydration of the sorbent and the protein surface, and (3) structural rearrangements in the protein molecule play major roles. Special attention is given to the relation between the structural stability …

Go to article

Some Observations On The Structure Of Encrusting Biofilms Of Proteus Mirabilis On Urethral Catheters, C. Winters, D. J. Stickler, N. S. Howe, T. J. Williams, N. Wilkinson, C. J. Buckley Jan 1995

Some Observations On The Structure Of Encrusting Biofilms Of Proteus Mirabilis On Urethral Catheters, C. Winters, D. J. Stickler, N. S. Howe, T. J. Williams, N. Wilkinson, C. J. Buckley

Cells and Materials

A physical model of the bladder has been used to study the process of urinary catheter encrustation. Techniques have been devised for the preparation of sections through these encrustations in situ on the luminal surfaces of catheters and for mapping the distribution of calcium and magnesium in the biofilms. Transmission electron microscopy on these sections showed struvite-like crystals lying in the matrix and in direct contact with the catheter surface. Calcium phosphate ("bioapatite") was distributed throughout the film and many of these amorphous particles appear to have cells at their cores. Freeze-substituted sections of biofilms also showed electron dense materials …

Go to article

Locally Weighted Polynomial Regression: Parameter Choice And Application To Forecasts Of The Great Salt Lake, Upmanu Lall, Young-Ii Moon, Ken Bosworth Jan 1995

Locally Weighted Polynomial Regression: Parameter Choice And Application To Forecasts Of The Great Salt Lake, Upmanu Lall, Young-Ii Moon, Ken Bosworth

Reports

Relationships between hydrologic variables are often nonlinear. Usually the functional form of such a relationship is not known a priori. A multivariate, nonparametric regression methodology is provided here for approximating the underlying regression function using locally veighted polynomials. Locally weighted polynomials consider the approximation of the target function through a Taylor series expansion of the function in the neighborhood of the point of estimate. Cross validatory procedures for the selection of the size of the neighborhood over which this approximation should take place, and for the order of the local polynomial to use are provided and shown for some simple …

Go to article

First Prev Next Last