Biomedical Devices and Instrumentation Commons^™

The Antibacterial Effects Of Zinc Ion Migration From Zinc-Based Glass Polyalkenoate Cements, D. Boyd, H. Li, D. A. Tanner, Mark R. Towler, J. G. Wall

Chemical and Biochemical Engineering Faculty Research & Creative Works

Zinc-based glass polyalkenoate cements have been synthesised and their potential use in orthopaedic applications investigated. Zinc ions were released from the materials in a rapid burst over the first 24 h after synthesis, with the release rate falling below detectable levels after 7 days. Cement-implanted bone samples were prepared, and the released zinc was shown, using energy dispersive X-ray analysis, to penetrate from the cement into the adjacent bone by up to 40 μm. Finally, the cements exhibited antibacterial activity against Streptococcus mutans and Actinomyces viscosus that reflected the pattern of zinc release, with the inhibition of growth greatest shortly …

An Investigation Into The Structure And Reactivity Of Calcium-Zinc-Silicate Ionomer Glasses Using Mas-Nmr Spectroscopy, D. Boyd, Mark R. Towler, R. V. Law, R. G. Hill

Chemical and Biochemical Engineering Faculty Research & Creative Works

The suitability of Glass Polyalkenoate Cements (GPCs) for orthopaedic applications is retarded by the presence in the glass phase of aluminum, a neurotoxin. Unfortunately, the aluminum ion plays an integral role in the setting process of GPCs and its absence is likely to hinder cement formation. However, the authors have previously shown that aluminum-free GPCs may be formulated based on calcium zinc silicate glasses and these novel materials exhibit significant potential as hard tissue biomaterials. However, there is no data available on the structure of these glasses. 29Si MAS-NMR, differential thermal analysis (DTA), X-ray diffraction (XRD), and network crosslink density …

Predictive Measures Of Tooth/Tooth Contact In Mastication, Elizabeth Klodd

Renée Crown University Honors Thesis Projects - All

Understanding the process of mastication, or chewing, is very important in humans. Understanding the way people chew can help craniofacial repair to victims of accidents or other conditions. Stages of chewing and swallowing have been categorized; however, it is currently unknown when exactly the teeth meet during mastication. Vertical motion data were obtained from seven subjects while chewing food of different consistencies. A videofluorograph collected the data and they were manipulated in Excel to be plotted as time vs. vertical displacement for the upper incisor tooth. The first and second derivatives of these motion-time charts were taken in order to …

Reliable In-Plane Velocity Measurements With Magnetic Resonance Velocity Imaging, Haosen Zhang, Sandra S. Halliburton, Andan K. Venkatachari, Randolph M. Setser, Richard D. White, George P. Chatzimavroudis

Chemical & Biomedical Engineering Faculty Publications

Magnetic resonance (MR) imaging is a well-known diagnostic imaging modality. In addition to its high-quality imaging capabilities, hydrogen-based MR can also provide non-invasively the velocity of water-based fluids in all three spatial directions (through-plane and in-plane) in an image. Many previous studies showed that MR velocity imaging can accurately measure the through-plane velocity. The aim of this study was to evaluate how reliable are the in-plane velocity measurements in an image. The axial velocity of water in horizontal tubes (inner diameter: 14.7–26.2 mm) was measured with segmented (fast) and non-segmented (slow) k-space MR velocity …

Ultrasonically Set Glass Polyalkenoate Cements For Orthodontic Applications, D. A. Tanner, N. Rushe, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

There is an accepted clinical requirement for a luting cement that can be command set upon satisfactory placement of an orthodontic appliance onto dentition. This work evaluates the suitability of ultrasound, imparted from a dental scaler, as a potential mechanism for achieving this. The net setting times and subsequent compressive strengths of a range of commercial and experimental glass polyalkenoate cements (GPCs) were evaluated, using modified ISO 9917 methods, when set both chemically and by ultrasound. The ultrasound was applied to the GPC through an orthodontic brace. It was possible to command set GPCs by the application of five to …

Optimisation Of The Composition Of An Acrylic Bone Cement: Application To Relative Amounts Of The Initiator And The Activator/Co-Initiator In Surgical Simplex®P, S. Madigan, M. R. Towler, G. Lewis

Chemical and Biochemical Engineering Faculty Research & Creative Works

In cemented arthroplasties, the two-part self-curing acrylic bone cement is currently the only material used for anchoring the total joint replacement to the contiguous bone. In virtually all commercially available formulations of this cement, the agents used for the initiation and activation/co-initiation of the radical polymerisation reaction are benzoyl peroxide (BPO) and N, N dimethyl-paratoluidine (DMPT), respectively. There are no reports in the open literature on the rationale for the amounts of these and other constituents in the formulations of the cement. Given the concerns that have been raised in the literature regarding the effect of residual DMPT on the …

Investigation Of The Electro-Mechanical Properties Of A Carbon Fiber-Sodium Composite Material For The Purpose Of Structural Health Monitoring, Sharon Austin

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Industrial Technology by Sharon Austin on November 15, 2005.

The Processing, Mechanical Properties And Bioactivity Of Zinc Based Glass Ionomer Cements, D. Boyd, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

The suitability of Glass Ionomer Cements (GICs) for use in orthopaedics is retarded by the presence in the glass phase of aluminium, a neurotoxin. Unfortunately, the aluminium ion plays an integral role in the setting process of a GIC and its absence is likely to hinder cement formation. However, zinc oxide, a bacteriocide, can act both as a network modifying oxide and an intermediate oxide in a similar fashion to alumina and so ternary systems based on zinc silicates often have extensive regions of glass formation. The purpose of this research was to produce novel GICs based on calcium zinc …

Laser And Led Effects On The Proliferation Rate Of Periodontal Ligament Fibroblasts, Allen J. Job

Loma Linda University Electronic Theses, Dissertations & Projects

PURPOSE: To compare the effectiveness of a Gallium Aluminum Arsenide (GaAlAs) diode laser and a light emitting diode (LED) on periodontal ligament fibroblast cell proliferative rates.

METHODS and MATERIALS: PDLF obtained from freshly extracted permanent teeth were cultured under standard conditions until a subconfluent monolayer was present. The next section took 5 days to complete. On day 1, the initial cell concentration of 700 uL/cm² was plated on 96-well assay plates and placed in a CO₂ incubator at 37° C for 24 hours. On day 2, cell counts were first verified using hemocytometry then were irradiated using an …

Blood Flow Measurements With Magnetic Resonance Phase Velocity Mapping, George P. Chatzimavroudis

Chemical & Biomedical Engineering Faculty Publications

Magnetic resonance (MR) phase velocity mapping (PVM) is a non-invasive technique that can measure the flow velocity in any spatial direction in an imaging slice. This technique has wide application in the clinical field in quantifying blood flow, as well as in non-biomedical areas. This review describes the value and/or potential of MR PVM as a diagnostic/monitoring technique in heart valve regurgitation and in the total cavo-pulmonary connection. A single slice placed in the aortic root can accurately quantify the aortic regurgitant volume. A multi-slice control volume method has high potential for the quantification of the mitral regurgitant volume. …

Physico-Chemical Characteristics Of European Pulverized Coal Combustion Fly Ashes, N. Moreno, X. Querol, J. M. Andrés, K. Stanton, Mark R. Towler, H. Nugteren, M. Janssen-Jurkovicová, R. Jones

Chemical and Biochemical Engineering Faculty Research & Creative Works

Fly ashes sourced from European pulverized coal burning power plants (from Spain, The Netherlands, Italy and Greece) were characterized in terms of their chemical composition, mineralogy and physical properties. The amount and composition of the glass present in the ashes were also determined. The materials analyzed have very different compositions and were selected with a view to determining their suitability for different applications and for further studies on applications. The results were compared to the literature to determine their similarities to UK coal fly ashes. Chemical analysis has enabled the categorization of the ashes based on their oxide contents. Devitrification …

Determining Suitability Of A Fly Ash For Silica Extraction And Zeolite Synthesis, Natàlia Moreno, Xavier Querol, Angel López-Soler, José Manuel Andres, Maria Janssen, Henk Nugteren, Mark R. Towler, Kenneth Stanton

Chemical and Biochemical Engineering Faculty Research & Creative Works

Zeolitic material is obtained from fly ash both by direct conversion of the ash or from SiO₂ extracts obtained from fly ash. This study focuses on determining the suitability of a fly ash for SiO₂ extraction and for zeolite synthesis by direct conversion. The SiO₂ extraction experiments from different fly ashes show that the main parameters governing the SiO₂ extraction are: (a) a high bulk SiO₂ content (> 52%, for obtaining an extraction yield of 100 g SiO₂ kg-1) in the starting fly ash, (b) a high proportion (> 55%) of the bulk SiO …

Techniques For Investigation Of Surgical Cutting Instruments, Eamon Price, Ger Reilly, Brendan Mccormack, Andrew Macey

Conference Papers

No abstract provided.

Investigation Into The Ultrasonic Setting Of Glass Ionomer Cements : Part Ii Setting Times And Compressive Strengths, E. Twomey, Mark R. Towler, C. M. Crowley, J. Doyle, S. Hampshire

Chemical and Biochemical Engineering Faculty Research & Creative Works

The ultrasonic setting of glass ionomer cements (GIC) was discussed. It was observed that the ultrasonic setting resulted in improvements of compressive strength. An increase in the PAA molecular weight from PAA50 to PAA200 resulted in an increase in the strength, but with a further increase in the PAA molecular weight to PAA450, there was a reduction in the strength. Results show that the strength of the ultrasonically set materials after 1 day were close to the values for the 7 days chemically set samples.

The Influence Of Strontium Substitution In Fluorapatite Glasses And Glass-Ceramics, R. G. Hill, A. Stamboulis, R. V. Law, A. Clifford, Mark R. Towler, C. Crowley

Chemical and Biochemical Engineering Faculty Research & Creative Works

Strontium is often substituted for calcium in order to confer radio-opacity in glasses used for dental cements, Biocomposites and bio glass-ceramics. The present paper investigates the influence of substituting strontium for calcium in a glass of the following composition: 4.5SiO₂3Al₂O ₃1.5P₂O₅3CaO2CaF₂, having a Ca:P ratio of 1.67 corresponding to calcium fluorapatite (Ca5(PO 4)3F). The glasses were characterized by magic angle spinning nuclear magnetic resonance (MAS-NMR), by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD). The ²⁹Si, ²⁷Al and ³¹P NMR spectra for the glasses with …

Characterisation Of The Glass Fraction Of A Selection Of European Coal Fly Ashes, J. Henry, Mark R. Towler, K. T. Stanton, X. Querol, N. Moreno

Chemical and Biochemical Engineering Faculty Research & Creative Works

Fly ash largely consists of the inorganic content of coal that remains after combustion. The crystalline phases present in fly ash may form upon cooling of a molten alumino-silicate glass. This view is supported by the spherical shape of many fly ash particles, inferring that they have gone through a viscous fluid state. The amorphous content in fly ash is believed to dominate reactivity behaviour, under both alkaline and acid conditions, because glasses have a higher potential energy than the equivalent crystal structure and the variation of bond angles and distances in a glass makes the bond breakage easier. It …

Preliminary Work On The Antibacterial Effect Of Strontium In Glass Ionomer Cements, A. Guida, Mark R. Towler, J. G. Wall, R. G. Hill, S. Eramo

Chemical and Biochemical Engineering Faculty Research & Creative Works

The antibacterial effect of strontium in glass ionomer cements (GIC) was discussed. The glass transition temperatures were found to decrease with the increasing fluorine content consistent with the fluorine replacing bridging oxygens. However no significant correlation was found between the fluoride release and the antibacterial activity.

Investigation Into The Ultrasound Setting Of Glass Ionomer Cements. Part I. Postulated Modalities, Mark R. Towler, C. M. Crowley, R. G. Hill

Chemical and Biochemical Engineering Faculty Research & Creative Works

Fuji IX glass is a low phosphate, low soda containing glass which has strontia incorporated as a radio-pacifier. This glass material was analyzed during exposure to different durations of ultrasound in an attempt to determine how the glass phase reacts. Cross sections of Fuji IX cement, set both conventionally and by ultrasound, were subsequently compared by microscopy. The resultant data were analyzed in detail.

Fluoride Release From Model Glass Ionomer Cements, A. Guida, R. G. Hill, Mark R. Towler, S. Eramo

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass ionomer cements (GICs) are an important class of biomedical material used extensively for color matched mercury free, dental restorations. GICs can release clinically beneficial amounts of fluoride and have acceptable handling properties which make them suitable as dental restoratives. The fluoride release of model GICs produced from specially synthesized fluoro-alumino-silicate glasses was studied. Nine glasses of varying fluoride content based on 4.5SiO₂-3Al₂O₃-1.5P₂O₅-(5-Z)CaO-ZCaF₂ were synthesized, and cement disks were prepared from them. The glass transition temperature reduced with increasing fluorine content of the glass. Fluoride ion release was measured …

A Preliminary Study Of An Aluminum-Free Glass Polyalkenoate Cement, Mark R. Towler, C. M. Crowley, D. Murphy, A. M.C. O'Callaghan

Chemical and Biochemical Engineering Faculty Research & Creative Works

No abstract provided.

Thermal Analysis Of Fly Ashes Sourced From European Non-Blended Coals, Kenneth T. Stanton, Mark R. Towler, Patrick Mooney, Robert G. Hill, Xavier Querol

Chemical and Biochemical Engineering Faculty Research & Creative Works

Fly ashes exist as a mixture of major amorphous phases and minor crystalline phases. For commercial applications, such as in concretes and for the production of zeolites, it would be desirable to be able to predict the reactivity of fly ashes. The amorphous phase dominates degradation behaviour, because glasses have a higher potential energy than the equivalent crystal structure and the variation of bond angles and distances in a glass make the bond breakage easier. Despite the large quantities of fly ash produced annually by coal-burning power plants, there have been very few studies investigating the microstructure and composition of …

Modelling Of The Glass Phase In Fly Ashes Using Network Connectivity Theory, Mark R. Towler, Kenneth T. Stanton, Patrick Mooney, Robert G. Hill, Natalia Moreno, Xavier Querol

Chemical and Biochemical Engineering Faculty Research & Creative Works

The amorphous phase of fly ash dominates degradation behaviour because glass has a higher potential energy than the equivalent crystal structure and the variation of bond angles and distances in a glass make the bond breakage easier. It would be advantageous to predict the presence and subsequent degradability of glass on the basis of the solid-state chemistry of the fly ash. To this end, and inorganic polymer model was applied to a selection of European fly ashes to determine the value known as cross-link density (CLD). A cross-link density value of less than two implies that the material is amorphous …

The Effect Of Low Levels Of Zirconia Addition On The Mechanical Properties Of Hydroxyapatite, Mark R. Towler, I. R. Gibson

Chemical and Biochemical Engineering Faculty Research & Creative Works

The effect of low levels of zirconia addition on the mechanical properties of hydroxyapatite was analyzed. Optimum amount of zirconia required to prevent decomposition of hydroxyapatite during sintering was determined. The particle size, morphology and surface area were measured and calcium to phosphorus ratio and trace element impurity content were determined by x-ray fluorescence. Low level addition of zirconia resulted in composites with better mechanical properties and minimum levels of decomposition.

The Crystallisation Of Glasses From The Ternary Caf2-Caal2si2o8-P2 O5 System, A. Clifford, R. G. Hill, Mark R. Towler, D. J. Wood

Chemical and Biochemical Engineering Faculty Research & Creative Works

A study of glasses from the ternary system CaF₂-CaAl₂Si₂O₈-P₂O₅ has been carried out. It has been shown that glasses with low phosphorus contents and high fluorite contents crystallise to fluorite. Fluorine reduces the glass transition temperature and is also required for the formation of fluorapatite (FAP). In the absence of fluorine in the glass no apatite phase is formed. Bulk nucleation of FAP is favoured for glasses with Ca:P ratios close to the apatite stoichiometry of 1.67 and with low crosslink densities. Thermal gravimetric analysis showed significant weight losses …

A Preliminary Comparison Of The Mechanical Properties Of Chemically Cured And Ultrasonically Cured Glass Ionomer Cements, Using Nano-Indentation Techniques, Mark R. Towler, A. J. Bushby, R. W. Billington, R. G. Hill

Chemical and Biochemical Engineering Faculty Research & Creative Works

There is a requirement for a dental cement with properties comparable or superior to conventional glass ionomer cements (GICs) but with the command set properties of the resin modified GICs. The objective of this work was to show that the application of ultrasound to conventional Fuji IX commercial glass ionomer cement imparts a command set, whilst improving the short-term surface mechanical properties. Nano-indentation techniques were employed to highlight the improvements in hardness and creep resistance imparted to the cement through the application of ultrasound. The instant set imparted by the application of ultrasound provides improved surface hardness and creep, particularly …

Novel Processing Of Hydroxyapatite-Zirconia Composites Using Nano-Sized Particles, Mark R. Towler, I. R. Gibson, S. M. Best

Chemical and Biochemical Engineering Faculty Research & Creative Works

A method to produce composites of hydroxyapatite (HA) with ZrO2 (Y-TZP) additions between 0 and 10 wt % at a low sinter temperature of 750 °C is presented. The method limits the amount of reaction between the HA and ZrO2. A ZrO2 loading level that would improve strength while limiting the decomposition of the HA is studied.

Effects Of Adding Sodium And Fluoride Ions To Glass Ionomer On Its Interactions With Sodium Fluoride Solution, R. W. Billington, P. C. Hadley, Mark R. Towler, G. J. Pearson, J. A. Williams

Chemical and Biochemical Engineering Faculty Research & Creative Works

This investigates the effects of the addition of Na and F ions to a glass ionomer cement in which those ions are not inherently present on its interactions with dilute (0.2%) NaF solution. Both the effect of the solution on the cement's surface morphology and the effect of the cement on the solution in terms of take up of Na⁺ and F^- and of change in pH are to be investigated. These results are to be compared to previous results obtained with glasses which contained both, one, or neither of the ions as components of their glasses. NaF …

The Influence Of Poly(Acrylic Acid) Molar Mass On The Properties Of Polyalkenoate Cements Formed From Zinc Oxide/Apatite Mixtures, Sinead Kenny, Robert G. Hill, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

The influence of poly (acrylic acid) molar mass was investigated on cements formed from zinc oxide-apatite mixtures at three aging times: one, seven and 28 days. Cements based on both hydroxyapatite and fluorapatite were investigated. The compressive strength, un-notched fracture strength and fracture toughness increased markedly with poly (acrylic acid) molar mass. The fracture toughness and un-notched fracture strength increased with aging time for the two highest molar mass cements but decreased with time for the two lowest molar mass cements. The greater chain entanglement density present in the higher molar mass cements is thought to contribute significantly to the …

Optimization Of Insertion Holes And Anchor Design For Cylinder Shaped Toggle Type Suture Anchors, Adam Fedenia

Masters Theses

This research was performed to optimize insertion holes and anchor design for cylinder shaped toggle type suture anchors. Four types of anchors were investigated in terms of pull strength and design in acrylic plate and pig bone. They included small type A and B anchors and large type A and B anchors.

Pull strength trends suggest that the small type anchors behave similarly since their external dimensions are identical, with the exception of type A anchor having a hole running from one end of the cylinder to the other like a pipe. It was found that the suture would fail …

Fetal Heart Rate Detection With A Passive Acoustic Sensor System, Zongyao Zhou

Electrical & Computer Engineering Theses & Dissertations

Research and development is presented of real time signal processing methodologies for the detection of fetal heart tones from noise contaminated signals obtained from passive acoustic sensors. A nonlinear Teager energy operator is utilized for detection of the fetal heart tone event. Autocorrelation and a parallel redundancy correction algorithm derives fetal heart rates. A real time monitoring system is described which records and plots the time history of both the fetal heart rate and the acoustic fetal heart signal. The system is validated in the context of the fetal nonstress test. Comparisons are made with ultrasonic nonstress tests on a …