Engineering Commons^™

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.

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 …

Simtm Turing Machine Simulator, Yin Fu Chen

Theses Digitization Project

No abstract provided.

Impulse, Dana Bieber, Jeremiah Gardner, Lois Hatton, Cindy Price

Impulse (Jerome J. Lohr College of Engineering Publication)

Features:
[Page 2-5] SDSU Engineering reaches all comers of the region
[Page 6] Students fly at ACE Camp
[Page 7] TAP-IN program helps defense industry
[Page 7] Balloon project up, up and away
[Page 8] ENTRE program successful in first year
[Page 8] ENTRE staff attends national conference
[Page 9] Electronics Engineering Technology program enters 10th year
[Page 10] SDSU/NASA tie strengthened by summer research
[Page 11] Space grant renewed for 1995
[Page 11] Private donations help support Ground Source Heat Pump Lab
[Page 11] SDSU helps Mitchell firm develop database system
Departments:
Faculty:
[Page 10] Two SDSU employees win …

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 …

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 …

Characterization Of Cadmium Sulfide Films Deposited By Chemical Bath Method, Quazi Galib Samdami, Hameed A. Naseem, W. D. Brown

Journal of the Arkansas Academy of Science

Thin filmcadmium sulfide is a leading candidate in the fabrication of large area solar cells. The chemical bath deposition method is one of the least expensive sources for the fabrication of device quality cadmium sulfide thin films.Inthe present work, the deposition of CdS films on glass substrate from an aqueous solution containing cadmium acetate, ammonia, ammonium acetate, and thiourea are investigated. The structural properties of CdS films are characterized. Good quality thin films within 0.1 - o.5 |im thickness were obtained in30 minute deposition time, and at 70*-90*C. The films show preferential orientations. The optical transmittance of the films are …

Undergraduate Engineering Ceramics Laboratory Development, Guna S. Selvaduray

Faculty Publications

No abstract provided.

Santa Clara Magazine, Volume 37 Number 1, Winter 1995, Santa Clara University

Santa Clara Magazine

6 - THE JESUIT CASE DECLASSIFIED Secret documents reveal what the United States knew.... and what it failed to do about the Jesuit murders in El Salvador. By Peter Kornbluh

10 - EASTERN ENLIGHTENMENT SCU's new religion chair draws from her latest book to discuss how Christians can derive a greater understanding of their own faith through an appreciation of Buddhism. By Denise Lardner Carmody

13 - WASTE NOT As part of SCU's Institute on Ecology, students, faculty, and staff assess how well the University is using its own environmental resources.

17 - THE DOMESTIC CHURCH MEETS THE PARISH CHURCH …

Response Of Ideally Controlled Canals To Downstream Withdrawals, Charles M. Burt, T. S. Strelkoff, J. L. Deltour

BioResource and Agricultural Engineering

No abstract provided.

Ua3/8/5 Wku Network Campus Map, Wku President's Office-Meredith

WKU Administration Documents

Map of WKU campus computer networking project.

Hardware Implementation Of The Complex Hopfield Neural Network, Chih Kang Cheng

Theses Digitization Project

No abstract provided.

Convergence Properties Of Perceptrons, Ratnasri Krishna Adharapurapu

Theses Digitization Project

No abstract provided.

Qpsk Block-Modulation Codes For Unequal Error Protection, Robert H. Morelos-Zaragoza, Shu Lin

Faculty Publications

Unequal error protection (UEP) codes find applications in broadcast channels, as well as in other digital communication systems, where messages have different degrees of importance. Binary linear UEP (LUEP) codes combined with a Gray mapped QPSK signal set are used to obtain new efficient QPSK block-modulation codes for unequal error protection. Several examples of QPSK modulation codes that have the same minimum squared Euclidean distance as the best QPSK modulation codes, of the same rate and length, are given. In the new constructions of QPSK block-modulation codes, even-length binary LUEP codes are used. Good even-length binary LUEP codes are obtained …

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.

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.

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 …

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 …

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 …

Models For Association Of Metal Ions With Heterogeneous Envimnmeatal Sorbents. 1 . Complexation Of Co(Ll) By Leonardiie Humic Acid As A Function Of Ph And Nac104 Concentration, John Westall, John Jones, Gary Turner, John M. Zachara

United States Department of Energy: Publications

A discrete log K spectrum model has been developed to represent the binding of protons and Co(II) to leonardite humic acid (LHA) over a wide variation of solution composition: pH 4.5-9.5, [NaC1O₄] 0.01 - 0.1 M, T_Co 200 nM-500 µM. The model is internally selfconsistent over the range indicated without an explicit electrostatic term. The LHA was represented by four acid sites (HL_i = H⁺ + L_i^-) with a fixed pK_a spectrum: pK_a = 4, 6, 8, and 10. From the acid base titration data, total concentrations of these sites …

Creep Fatigue, Part Iii: Diercks Equation: Modification And Applicability, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

Creep-fatigue data of low allow steels were compiled from international sources, and trends in creep-fatigue behavior were identified in Paper I. Methods of life prediction and their trends were examined in Paper II with respect to compiled data. Diercks equation, a multivariate creep-fatigue life extrapolation equation, for SS, 304, in terms of strain range, temperature, hold time and strain rate parameters is modified and extended to the life prediction of low alloy steels in this paper.

Large Scale Isolation Of Expression Vector Cassette By Magnetic Triple Helix Affinity Capture, Srinivas V. Sonti, Matthew C. Griffor, T. Sano, S. Narayanswami, Arijit Bose, C. R. Cantor, Albert P. Kausch

Chemical, Biomolecular, and Materials Engineering Faculty Publications

No abstract provided.

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 …

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 …

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 …

Maximizing Conjunctive Use Of Surface And Ground Water Under Surface Water Quality Constraints, Muhammad Shafqat Ejaz, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

A simulation/optimization (s/o) model is presented to address the increasingly common conflicts between water quantity and quality objectives. The model can assist water resources analysts in selecting compromise strategies for stream/aquifer systems in which the stream gains water from the aquifer. The water quantity objective is to maximize steady conjunctive use of groundwater and surface water resources. The water quality objective is to maximize waste loading from a sewage treatment plant {STP) to the stream without violating downstream water quality beyond acceptable limits. The STP discharge is proportional to human population. The two objectives conflict because an increase in groundwater …

Treatment Of Pentachlorophenol With Manganese Oxide Addition To Biotic And Abiotic Sediments, R. Petrie, J. E. Mclean, Ronald C. Sims

Biological Engineering Faculty Publications

Laboratory microcosms containing subsamples of a complex environmental sediment were used to evaluate the addition of oxidized manganese as the primary electron acceptor in the presence of pentachlorophenol (PCP) as the primary electron donor. Manganese oxide (MnO₂) particles were added to poisoned abiotic and non-poisoned biotic microcosms and incubated at 11°C in the presence of sediment samples that were shown capable of mineralizing PCP with indigenous microorganisms. Reduction in PCP concentration and production of reduced manganese was measured for both abiotic and biotic systems.

PCP was observed to be transformed most rapidly and to the greatest extent in …

Evaluation Of Biological Treatability Of Soil Contaminated With Manufactured Gas Plant Waste, J. S. Ginn, Ronald C. Sims, I. P. Murarka

Biological Engineering Faculty Publications

The biological treatability of subsurface soil contaminated with manufactured gas plant (MGP) waste was evaluated. Mineralization assays incorporating ¹⁴C-phenanthrene were used to evaluate the biotransformation potential of indigenous microorganisms at the site. Multi-phase laboratory microcosms were used to evaluate the interphase transfer potential and chemical mass distribution of phenanthrene. The Microtox™ bioassay was used to evaluate detoxification trends at the site. Mineralization results indicated that indigenous microorganisms at the site were capable of transforming phenanthrene, a component of coal-tar creosote. Results also indicated that spiked ¹⁴C-phenanthrene mineralization was influenced by nutrient addition and by the amount of contamination. …

Mn-Catalyzed Oxidation Of Multiple-Ringed Aromatics, G. Whelan, Ronald C. Sims

Biological Engineering Faculty Publications

The role of manganese (Mn) oxides in catalyzing the abiotic oxidation of polynuclear aromatic compounds (PNAs) has been investigated by monitoring the oxidation of dihydrodiol and dione PNAs and corresponding reduction of Mn in an aqueous environment. 1,4-, 1,3-, and 2,3-naphthalenediol, 1,4-naphthoquinone, and l,4-dihydroxy-9,10-anthracenedione (Quinizarin) were oxidized in an oxic, aqueous environment, where each of these organic compounds is soluble in water, except Quinizarin. A mathematical model is presented, which describes the redox reactions, and suggests that electron transfer/organic release from the oxide surface is rate limiting with the reaction apparently proceeding through a free-radical formation. Results indicate significant oxidation …

Mn-Catalyzed Oxidation Of Naphthalenediol, G. Whelan, Ronald C. Sims

Biological Engineering Faculty Publications

This study investigates the effects that manganese(IV) dioxide particles have on 2,3-naphthalenediol at varying pH levels (i.e., initial pH of 4.58, 5.85, and 8.75) and under different organic concentration conditions (4×¹⁰⁻³, 4×¹⁰⁻⁴, and 4×¹⁰⁻⁵ M), and assesses the importance of Mn oxides on abiotic catalysis of the multiple-ringed aromatic compound. Proton concentration affected the rates of reductive dissolution; as the pH values increased, the rate of reductive dissolution decreased, as predicted by theory. Also, as the concentration of naphthalenediol increased, the rate of reductive dissolution increased, although not proportionally; thus indicating that a majority of …