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Chemical and Biochemical Engineering Faculty Research & Creative Works

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Full-Text Articles in Biochemical and Biomolecular Engineering

Comparison Of Microwave And Conventionally Sintered Yttria-Doped Zirconia Ceramics, Colin J. Reidy, Thomas J. Fleming, Stuart Hampshire, Mark R. Towler Nov 2011

Comparison Of Microwave And Conventionally Sintered Yttria-Doped Zirconia Ceramics, Colin J. Reidy, Thomas J. Fleming, Stuart Hampshire, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

This paper reports on improvement of the physical and mechanical properties of Y2O3-ZrO2 ceramics through compositional optimization, the use of nanograined powders and utilization of microwave sintering. ZrO2 with 2-5 mol% Y2O3, prepared from nanopowders, was sintered in both conventional and microwave furnaces under exactly the same heating schedule. It was found that microwave sintering improves physical and mechanical properties of Y2O3-ZrO2 ceramics compared with conventional sintering. Compositions containing 2 mol% Y2O3 exhibit the greatest improvement due to retention of tetragonal ZrO …

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Γ-Ct Measurement And Cfd Simulation Of Cross Section Gas Holdup Distribution In A Gas-Liquid Stirred Standard Rushton Tank, Yue Jin Liu, Wei Li, Lu Chang Han, Yang Cao, He An Luo, Muthanna H. Al-Dahhan, M. P. Dudukovic Sep 2011

Γ-Ct Measurement And Cfd Simulation Of Cross Section Gas Holdup Distribution In A Gas-Liquid Stirred Standard Rushton Tank, Yue Jin Liu, Wei Li, Lu Chang Han, Yang Cao, He An Luo, Muthanna H. Al-Dahhan, M. P. Dudukovic

Chemical and Biochemical Engineering Faculty Research & Creative Works

Cross Section Gas Holdup Distributions at 3/4 Dimensionless Static Liquid Height in a Gas-Liquid Stirred Standard Rushton Tank Were Measured using 137Cs Γ-CT Scan Measuring Technology at Larger Gas Flow Rates and Higher Impeller Rotating Speeds. the Obtained CT Scan Images and Digital Distribution Curves of Gas Holdup with Dimensionless Radius based on the CT Images Could Explain the Fluctuation Changes of Gas Holdup Distribution. the Dense Area of Gas Holdup Distribution Appeared in the Upper Space of Impeller Blades. Gas Holdup Increased Both with Gas Flow Rate and Impeller Rotating Speed, But Gas Flow Rate Had More Influence on …

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Sol-Gel Derived Silver-Incorporated Titania Thin Films On Glass: Bactericidal And Photocatalytic Activity, Betul Akkopru Akgun, Anthony W. Wren, Caner Durucan, Mark R. Towler, Nathan P. Mellott Aug 2011

Sol-Gel Derived Silver-Incorporated Titania Thin Films On Glass: Bactericidal And Photocatalytic Activity, Betul Akkopru Akgun, Anthony W. Wren, Caner Durucan, Mark R. Towler, Nathan P. Mellott

Chemical and Biochemical Engineering Faculty Research & Creative Works

Titanium dioxide (TiO2) and silver-containing TiO2 (Ag-TiO2) thin films were prepared on silica pre-coated float glass substrates by a sol-gel spin coating method. The bactericidal activity of the films was determined against Staphylococcus epidermidis under natural and ultraviolet (UV) illumination by four complementary methods; (1) the disk diffusion assay, (2) UV-induced bactericidal test, (3) qualitative Ag ion release in bacteria inoculated agar media and (4) surface topographical examination by laserscan profilometry. Photocatalytic activity of the films was measured through the degradation of stearic acid under UV, solar and visible light conditions. The chemical state and …

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Clinical Risk Factors For Osteoporosis In Ireland And The Uk: A Comparison Of Frax And Qfracturescores, N. M. Cummins, E. K. Poku, Mark R. Towler, O. M. O'Driscoll, S. H. Ralston Aug 2011

Clinical Risk Factors For Osteoporosis In Ireland And The Uk: A Comparison Of Frax And Qfracturescores, N. M. Cummins, E. K. Poku, Mark R. Towler, O. M. O'Driscoll, S. H. Ralston

Chemical and Biochemical Engineering Faculty Research & Creative Works

Recently two algorithms have become available to estimate the 10-year probability of fracture in patients suspected to have osteoporosis on the basis of clinical risk factors: the FRAX algorithm and QFractureScores algorithm (QFracture). The aim of this study was to compare the performance of these algorithms in a study of fracture patients and controls recruited from six centers in the United Kingdom and Ireland. A total of 246 postmenopausal women aged 50-85 years who had recently suffered a low-trauma fracture were enrolled and their characteristics were compared with 338 female controls who had never suffered a fracture. Femoral bone mineral …

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The Effect Of Adding Organic Polymers To Ca-Sr-Zn-Si Glass Polyalkenoate Cement, A. Coughlan, N. M. Cummins, A. W. Wren, Mark R. Towler Jun 2011

The Effect Of Adding Organic Polymers To Ca-Sr-Zn-Si Glass Polyalkenoate Cement, A. Coughlan, N. M. Cummins, A. W. Wren, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

To conclude, the addition of polymers to GPCs resulted in little change to the Tw and Ts, however the compressive strength was found to decrease slightly. ASAP tests revealed that the cements may undergo some structural changes as a result of these additions. In the future perhaps the addition of organic polymers suspended in the liquid phase as part of the cement may yield improved results in this type of study. © 2011 IEEE.

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Aluminium-Free Glass Polyalkenoate Spinal Cements, A. W. Wren, N. M. Cummins, Mark R. Towler Jun 2011

Aluminium-Free Glass Polyalkenoate Spinal Cements, A. W. Wren, N. M. Cummins, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Addition of Yitanium increased the Wt & St and the sf strength of these cements compared to the control (BT 101). © 2011 IEEE.

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Leaching Of Potential Hazardous Elements Of Coal Cleaning Rejects, Luis F.O. Silva, Maria Izquierdo, Xavier Querol, Robert B. Finkelman, Marcos L.S. Oliveira, Marcus Wollenschlager, Mark R. Towler, Rafael Pérez-López, Felipe Macias Apr 2011

Leaching Of Potential Hazardous Elements Of Coal Cleaning Rejects, Luis F.O. Silva, Maria Izquierdo, Xavier Querol, Robert B. Finkelman, Marcos L.S. Oliveira, Marcus Wollenschlager, Mark R. Towler, Rafael Pérez-López, Felipe Macias

Chemical and Biochemical Engineering Faculty Research & Creative Works

The geochemical characteristics of coal cleaning rejects (CCR) in Santa Catarina State, Brazil, were investigated. Around 3.5 million ton/ year of coal waste are dumped in Santa Catarina State. Coal beneficiation by froth flotation results in large amounts of CCR composed of coaly and mineral matter, the latter characterized by the occurrence of sulphide minerals and a broad array of leachable elements. The total and leachable contents of more than 60 elements were analyzed. Atmospheric exposure promotes sulphide oxidation that releases substantial sulphate loads as well as Ca2+, K+, Mg2+, Cl- and Al3+ …

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Verification And Validation Of Cfd Simulations For Local Flow Dynamics In A Draft Tube Airlift Bioreactor, Hu Ping Luo, Muthanna H. Al-Dahhan Mar 2011

Verification And Validation Of Cfd Simulations For Local Flow Dynamics In A Draft Tube Airlift Bioreactor, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Airlift Reactors Have Been Recognized as One of the Promising Photobioreactors for Biomass/bio-Energy Production, Where Mixing Has Significant Impact on the Reactor Performance. in Recent Years, using CFD Simulations to Track Microorganism Cells and to Generate their Trajectories in the Reactor for Reactor Performance Evaluations Becomes More Common. However, there is a Lack of Systematic and Rigorous Verifications and Validations of the Reliability of CFD Models in Particle Tracking Against Experimental Measurements in the Open Literature, Which is Vital for the Faithful Application of CFD in Reactor Design and Scale-Ups. in This Work, We Attempt to Evaluate the Reliability of …

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The Structural Role Of Titanium In Ca-Sr-Zn-Si/Ti Glasses For Medical Applications, A. W. Wren, F. R. Laffir, A. Kidari, Mark R. Towler Feb 2011

The Structural Role Of Titanium In Ca-Sr-Zn-Si/Ti Glasses For Medical Applications, A. W. Wren, F. R. Laffir, A. Kidari, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glasses for medical applications are used in particulate form or as a cement component. This work was undertaken to determine structural changes in 0.48SiO2-0.36ZnO-0.12CaO-0.04SrO glass when the SiO2 is substituted with 5 mol% increments of TiO2. X-ray Diffraction (XRD) was used to determine the presence of crystallinity. This occurred after additions of 20 mol% TiO2. Differential Thermal Analysis (DTA) and Network connectivity (NC) calculations determined that by increasing the TiO2 content, the Tg and NC reduced (Tg 670 °C to 632 °C, NC 1.83 to -1.14) suggesting that TiO2 acts as …

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Flow Regime Identification In A Bubble Column Via Nuclear Gauge Densitometry And Chaos Analysis, S. Nedeltchev, A. Shaikh, Muthanna H. Al-Dahhan Feb 2011

Flow Regime Identification In A Bubble Column Via Nuclear Gauge Densitometry And Chaos Analysis, S. Nedeltchev, A. Shaikh, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Bubble Column Performance Can Change Significantly as a Result of Flow Regime Change. Since Reactor Volume Productivity, Mass and Heat Transfer as Well as Mixing Are Affected by the Prevailing Flow Regime, It is Very Important to Know How to Identify It. in This Work, Flow Regime Identification Was Performed on the Basis of the Kolmogorov Entropy (KE) Algorithm Applied to Nuclear Gauge Densitometry Data. in Addition, the Average Cycle Time Was Used for Validation of the Results. Three Transition Velocities Were Identified that Delineated the Boundaries of the Three Main Hydrodynamic Regimes. the First Two Transition Points Were …

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The Bioactivity And Ion Release Of Titanium-Containing Glass Polyalkenoate Cements For Medical Applications, A. W. Wren, N. M. Cummins, F. R. Laffir, S. P. Hudson, Mark R. Towler Jan 2011

The Bioactivity And Ion Release Of Titanium-Containing Glass Polyalkenoate Cements For Medical Applications, A. W. Wren, N. M. Cummins, F. R. Laffir, S. P. Hudson, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

The ion release profiles and bioactivity of a series of Ti containing glass polyalkenoate cements. Characterization revealed each material to be amorphous with a Tg in the region of 650-660°C. The network connectivity decreased (1.83-1.35) with the addition of TiO2 which was also evident with analysis by X-ray photoelectron spectroscopy. Ion release from cements were determined using atomic absorption spectroscopy for zinc (Zn2+), calcium (Ca2+), strontium (Sr2+), Silica (Si4+) and titanium (Ti4+). Ions such as Zn2+ (0.1-2.0 mg/l), Ca2+ (2.0-8.3 mg/l,) Sr2+ (0.1-3.9 mg/l), and Si4+ …

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The Response Of Pseudomonas Aeruginosa Biofilm To The Presence Of A Glass Polyalkenoate Cement Formulated From A Silver Containing Glass, A. Coughlan, M. P. Ryan, N. M. Cummins, Mark R. Towler Jan 2011

The Response Of Pseudomonas Aeruginosa Biofilm To The Presence Of A Glass Polyalkenoate Cement Formulated From A Silver Containing Glass, A. Coughlan, M. P. Ryan, N. M. Cummins, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

No abstract provided.

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Polymer (Su-8) Optofluidic Device With Embedded Hydrogel Oxygen Sensing Elements, Zhan Gao, David B. Henthorn, Chang-Soo Kim Dec 2010

Polymer (Su-8) Optofluidic Device With Embedded Hydrogel Oxygen Sensing Elements, Zhan Gao, David B. Henthorn, Chang-Soo Kim

Chemical and Biochemical Engineering Faculty Research & Creative Works

The SU-8 photopolymer is an excellent alternative for traditional materials used in fluidic devices such as glass- or silicon-Based inorganic materials. We describe a new chemically anchored, lithographically patterned hydrogel sensing element embedded in a completed SU-8 fluidic channel structure after the channel bonding process. Polyethylene glycol (PEG) hydrogel films incorporating oxygen-responsive ruthenium-complex fluorophores are grafted and patterned by photopolymerization of solution-phase precursors on the modified SU-8 channel surface. the optofluidic sensing platform with this embedded sensing elements exhibited excellent performance in measuring dissolved oxygen content. a unique advantage of this method is the selective growth of various functional films …

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Enhancing Oxygen Reduction Reaction Activity Via Pd-Au Alloy Sublayer Mediation Of Pt Monolayer Electrocatalysts, Yangchuan Xing, Yun Cai, Miomir B. Vukmirovic, Wei Ping Zhou, Hiroko Karan, Jia X. Wang, Radoslav R. Adzic Nov 2010

Enhancing Oxygen Reduction Reaction Activity Via Pd-Au Alloy Sublayer Mediation Of Pt Monolayer Electrocatalysts, Yangchuan Xing, Yun Cai, Miomir B. Vukmirovic, Wei Ping Zhou, Hiroko Karan, Jia X. Wang, Radoslav R. Adzic

Chemical and Biochemical Engineering Faculty Research & Creative Works

New Pt monolayer electrocatalysts were prepared using galvanic displacement of a copper monolayer deposited at underpotentials on a Pd core. by performing underpotential deposition twice, two monolayers were deposited, forming a core-shell structure with double shells. the double shells consist of an outermost shell of Pt monolayer and a sublayer shell of Pd-Au alloy. It was found that by adjusting the compositions of the alloy sublayer, it is possible to mediate the oxygen reduction reaction (ORR) activity of the Pt catalysts. an alloy with 10% (atomic) Au was found to be the most active among the catalysts tested. Furthermore, the …

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Labyrinthine Instability In Thin Liquid Films, P. Neogi Oct 2010

Labyrinthine Instability In Thin Liquid Films, P. Neogi

Chemical and Biochemical Engineering Faculty Research & Creative Works

When a thin liquid film on a solid surface has a thickness corresponding to a particular part the spinodal region of the disjoining pressure versus thickness isotherm, the film breaks down. One of the patterns that emerges on the breakdown has been referred to as wavy instability. It is compared here to the labyrinthine instability seen in magnetic films. the system is modeled following the procedure used in magnetic systems, and the pattern of wavy instability is broken down into a curved thick-thin film in equilibrium with a flat thin-thin film of constant thickness. Minimization of free energy leads to …

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Comparison Of Antibacterial Properties Of Commercial Bone Cements And Fillers With A Zinc-Based Glass Polyalkenoate Cement, A. W. Wren, N. M. Cummins, Mark R. Towler Oct 2010

Comparison Of Antibacterial Properties Of Commercial Bone Cements And Fillers With A Zinc-Based Glass Polyalkenoate Cement, A. W. Wren, N. M. Cummins, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Postoperative infection following invasive surgical procedures is a significant cause for concern, particularly in spinal reconstructive surgery. The objective of this study is to compare the antibacterial efficacy of a novel zinc-based glass polyalkenoate cement (Zn-GPC) based on 0.04SrO-0.12CaO-0.36ZnO- 0.48SiO2 glass, to a number of commercially available bone cements and fillers including Simplex P + Tobramycin (STob), Spineplex (Spine) and Novabone Putty (NPut). The agar diffusion test was performed on each material against Escherichia coli, Staphlococcus epidermidis, Pseudomonas aeruginosa and Staphlococcus Aureus. STob was found to produce large inhibition zones in each …

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The Effect Of Ionic Dissolution Products Of Ca-Sr-Na-Zn-Si Bioactive Glass On In Vitro Cytocompatibility, S. Murphy, A. W. Wren, Mark R. Towler, D. Boyd Oct 2010

The Effect Of Ionic Dissolution Products Of Ca-Sr-Na-Zn-Si Bioactive Glass On In Vitro Cytocompatibility, S. Murphy, A. W. Wren, Mark R. Towler, D. Boyd

Chemical and Biochemical Engineering Faculty Research & Creative Works

Many commercial bone grafts cannot regenerate healthy bone in place of diseased bone. Bioactive glasses have received much attention in this regard due to the ability of their ionic dissolution products to promote cell proliferation, cell differentiation and activate gene expression. Through the incorporation of certain ions, bioactive glasses can become therapeutic for specific pathological situations. Calcium-strontium-sodium-zinc-silicate glass bone grafts have been shown to release therapeutic levels of zinc and strontium, however the in vitro compatibility of these materials is yet to be reported. In this study, the in vitro cytocompatibility of three different calcium-strontium-sodium-zinc-silicate glasses was examined as a …

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A Spectroscopic Investigation Into The Setting And Mechanical Properties Of Titanium Containing Glass Polyalkenoate Cements, A. W. Wren, A. Kidari, N. M. Cummins, Mark R. Towler Aug 2010

A Spectroscopic Investigation Into The Setting And Mechanical Properties Of Titanium Containing Glass Polyalkenoate Cements, A. W. Wren, A. Kidari, N. M. Cummins, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Titanium (Ti) implants are extensively used in a number of biomedical and dental applications. This work introduces Ti into the glass phase of a zinc-based glass polyalkenoate cement (GPC) and investigates changes in handling and mechanical properties considering two molecular weight polyacrylic acids (PAA), E9 and E11. Considering the handling properties, the working time (Tw) increased from 50 sE9, 32 sE11 (BT 101, Ti-free) to 169 sE9, 74 sE11 with TW-Z (highest Ti content), respectively. The setting time (Ts) increased from 76 sE9, 47 sE11 (BT 101) …

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A New Methodology For Hydrodynamic Similarity In Bubble Columns, Ashfaq Shaikh, Muthanna H. Al-Dahhan Aug 2010

A New Methodology For Hydrodynamic Similarity In Bubble Columns, Ashfaq Shaikh, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Bubble Columns Are Widely Used in Chemical, Petrochemical, and Biochemical Industries for Various Processes Such as Alkylation, Oxidation, Chlorination, Wet Oxidation of Effluents, Etc. a New Hypothesis for Hydrodynamic Similarity that Can Be Subsequently Used for Scale-Up of Bubble Column Reactors Was Proposed. This Hypothesis Was Evaluated using Advanced Diagnostic Techniques. the Conditions of Similarity Where overall Gas Holdup and Radial Gas Holdup Profiles Were the Same, and Mismatch Where overall Gas Holdup Was the Same But Gas Holdup Radial Profiles Were Different, Were Identified. the Condition that Two Systems Must Operate in the Same Flow Regime to Be Hydrodynamically …

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Local Gas Holdup In A Draft Tube Airlift Bioreactor, Hu Ping Luo, Muthanna H. Al-Dahhan Aug 2010

Local Gas Holdup In A Draft Tube Airlift Bioreactor, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Airlift Column Bioreactors Are Gas-Liquid Contact Devices Characterized by a Rising Channel and a Down Flow Channel Due to Gas Holdup Differences in These Two Channels. Local Gas Holdup Distribution Strongly Affects the overall Gas-Liquid Flow Dynamics in Airlift Columns. in This Work, Local Gas Holdup Distributions in a Draft Tube Airlift Column Covering Both Bubbly Flow and Churn-Turbulent Flow Regimes Have Been Studied using Computed Tomography (CT) Technique as Well as Conventional Techniques. the Radial and Axial Evolutions of the Gas Holdup Distribution Will Be Discussed, Together with the Effects of Superficial Gas Velocity and Geometry Parameters. the Obtained …

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Crystallization Method For Benzphetamine, Dennis J. Kalota, Keith Tomazi Jul 2010

Crystallization Method For Benzphetamine, Dennis J. Kalota, Keith Tomazi

Chemical and Biochemical Engineering Faculty Research & Creative Works

There is disclosed a method for the crystallization of benzphetamine hydrochloride from an organic medium by the steps of removing water from the system to a very low level and then reducing the temperature of the organic medium to provide crystallization of the acid salt. In the event that crystallization does not occur upon lowering the temperature of the medium, it has been discovered that gentle heating of the organic medium results in crystallization of the acid salt. It has also been discovered that higher temperature crystallization has been provided by removal of methamphetamine from the composition. The crystalline benzphetamine …

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The Effect Of Adding Organic Polymers On The Handling Properties, Strengths And Bioactivity Of A Ca-Sr-Zn-Si Glass Polyalkenoate Cement, A. W. Wren, N. M. Cummins, A. Coughlan, Mark R. Towler Jul 2010

The Effect Of Adding Organic Polymers On The Handling Properties, Strengths And Bioactivity Of A Ca-Sr-Zn-Si Glass Polyalkenoate Cement, A. W. Wren, N. M. Cummins, A. Coughlan, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

This work demonstrates the addition of a number of naturally occurring proteins/polymers to a zinc-based glass polyalkenoate cements (GPCs). Chitin (Chi.), collagen (Col.), cysteine (Cys.) and keratin (Ker.) were added with the intention of improving the bioactivity of this cement. Initial testing involved characterization of the glass with X-ray diffraction (XRD) and differential thermal analysis (DTA) before and after sterilization with γ-irradiation. No significant changes occurred as a result of sterilization. Handling properties of the modified cements were not significantly different from those of the control, BT 101 (Working Tw-36s, and setting time Ts-70 …

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Influence Of Morphology And Processing On Xps Characterisation Of Sro-Ca-Zno-Sio2 Glass, F. R. Laffir, A. W. Wren, Mark R. Towler Jun 2010

Influence Of Morphology And Processing On Xps Characterisation Of Sro-Ca-Zno-Sio2 Glass, F. R. Laffir, A. W. Wren, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

A study was conducted to demonstrate the influence of morphology and processing on X-ray photoelectron spectroscopic (XPS) characterization SrO-Ca-ZnO-SiO2 glass. The glass formulation being investigated was originally synthesized for developing a novel glass polyalkenoate cement (GPC). High resolution photoelectron spectra of Zn 2p, Ca 2p, Sr 3d, Si 2p, O 1s, and C 1s were recorded for the different forms of glass. It was observed that there was preferential enrichment of Zn2+ with an increase in the proportion of NBO for the investigated BT101 glass. The relative atomic concentration of Zn in BT101 glass was high and resulted …

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Synthesis Of Pegylated Single Wall Carbon Nanotubes By A Photoinitiated Graft From Polymerization, Pu Zhang, David B. Henthorn Jun 2010

Synthesis Of Pegylated Single Wall Carbon Nanotubes By A Photoinitiated Graft From Polymerization, Pu Zhang, David B. Henthorn

Chemical and Biochemical Engineering Faculty Research & Creative Works

A considerable amount of research has been devoted to carbon nanotubes because of their unique electrical, mechanical, optical, and chemical properties. Here, in this report, we introduce a novel, simple ultraviolet initiated "graft from" polymerization method to synthesize PEGylated carbon nanotubes. This grafting procedure significantly enhanced nanotube aqueous dispersibility and long-term stability in solution. Mass of grafted polymer chains was easily modulated by adjusting polymerization reaction time, and nanomaterials containing up to 80% polymer by weight were synthesized. Nanotube morphology was characterized by SEM, TEM before and after the functionalization. in addition, the covalent bonding of polymer chains to the …

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Mechanical Properties Of Hydroxyapatite-Zirconia Compacts Sintered By Two Different Sintering Methods, Declan J. Curran, Thomas J. Fleming, Mark R. Towler, Stuart Hampshire Apr 2010

Mechanical Properties Of Hydroxyapatite-Zirconia Compacts Sintered By Two Different Sintering Methods, Declan J. Curran, Thomas J. Fleming, Mark R. Towler, Stuart Hampshire

Chemical and Biochemical Engineering Faculty Research & Creative Works

Microwave sintering is traditionally employed to reduce the sintering temperature required to densify powder compacts. The effect of microwave heating on hydroxyapatite (HA)-zirconia (ZrO2) green bodies has been investigated in order to understand how microwave energy may affect the physical and mechanical properties of the resultant densified composites. Laboratory synthesised nano-sized HA and a commercial nano-sized ZrO2 powder have been ball milled to create mixtures containing 0-5 wt% ZrO2 loadings. Compacts were microwave sintered at either 700, 1000 or 1200°C with a 1 h hold time. Comparative firings were also performed in a resistive element furnace …

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Evaluation Of Two Novel Aluminum-Free, Zinc-Based Glass Polyalkenoate Cements As Alternatives To Pmma Bone Cement For Use In Vertebroplasty And Balloon Kyphoplasty, Gladius Lewis, Mark R. Towler, Daniel Boyd, Matthew J. German, Anthony W. Wren, Owen M. Clarkin, Andrew Yates Jan 2010

Evaluation Of Two Novel Aluminum-Free, Zinc-Based Glass Polyalkenoate Cements As Alternatives To Pmma Bone Cement For Use In Vertebroplasty And Balloon Kyphoplasty, Gladius Lewis, Mark R. Towler, Daniel Boyd, Matthew J. German, Anthony W. Wren, Owen M. Clarkin, Andrew Yates

Chemical and Biochemical Engineering Faculty Research & Creative Works

Vertebroplasty (VP) and balloon kyphoplasty (BKP) are now widely used for treating patients in whom the pain due to vertebral compression fractures is severe and has proved to be refractory to conservative treatment. These procedures involve percutaneous delivery of a bolus of an injectable bone cement either directly to the fractured vertebral body, VB (VP) or to a void created in it by an inflatable bone tamp (BKP). Thus, the cement is a vital component of both procedures. In the vast majority of VPs and BKPs, a poly(methyl methacrylate) (PMMA) bone cement is used. This material has many shortcomings, notably …

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Temperature-Induced Restructuring Of Self-Assembled Ptpd Nanoparticle Superlattices, Guoqiang Ren, Yangchuan Xing Nov 2009

Temperature-Induced Restructuring Of Self-Assembled Ptpd Nanoparticle Superlattices, Guoqiang Ren, Yangchuan Xing

Chemical and Biochemical Engineering Faculty Research & Creative Works

PtPd nanoparticle superlattices were prepared at room temperature and investigated for their restructuring at elevated temperatures. the PtPd nanoparticles were spherical with a diameter of 3.5±0.3nm and were capped with surfactants of oleic acids and oleylamine. Images of the nanoparticle superlattices were taken using a transmission electron microscope. Analysis of the images with fast Fourier transform (FFT) revealed whether the superlattices were crystalline or amorphous. It was found that the critical temperature that induced a phase transition of PtPd superlattices from a crystalline state to an amorphous state fall in the range of 100-110 °C. Meanwhile, heat-induced restructuring transformed less-ordered …

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Fabrication Of Spherical Cao-Sro-Zno-Sio2 Particles By Sol-Gel Processing, Ill Yong Kim, Mark R. Towler, Anthony Wren, Chikara Ohtsuki Nov 2009

Fabrication Of Spherical Cao-Sro-Zno-Sio2 Particles By Sol-Gel Processing, Ill Yong Kim, Mark R. Towler, Anthony Wren, Chikara Ohtsuki

Chemical and Biochemical Engineering Faculty Research & Creative Works

This study was concerned with the fabrication of ceramic CaO-SrO-ZnO-SiO2 spherical particles, which are novel candidates for the glass phase in glass polyalkenoate cements (GPCs). GPCs made from these glasses have potential as bone cements because, unlike conventional GPCs, they do not contain aluminum ions, which inhibit the calcification of hydroxyapatite in the body. The glass phase of GPCs require a controllable glass morphology and particle size distribution. Sol-gel processing can potentially be used to fabricate homogenous ceramic particles with controlled morphology. However, a thorough study on preparation conditions of spherical CaO-SrO-ZnO-SiO2 particles by sol-gel processing has, to …

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Characterisation And Mechanical Testing Of Hydrothermally Treated Ha/Zro2 Composites, D. J. Curran, T. J. Fleming, G. Kawachi, C. Ohtsuki, Mark R. Towler Nov 2009

Characterisation And Mechanical Testing Of Hydrothermally Treated Ha/Zro2 Composites, D. J. Curran, T. J. Fleming, G. Kawachi, C. Ohtsuki, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Hydrothermal treatment is traditionally employed to improve the sinterability of powder compacts by reducing porosity and increasing apparent density. The effect of hydrothermal treatment on green powder compacts has been assessed in order to better understand how treatment may affect the sinter ability of the bodies. Laboratory synthesized nano sized hydroxyapatite (HA) and a commercial zirconia (ZrO2) powder have been ball milled together to create composite mixtures containing 0-5 wt% ZrO2 loadings. Disc shaped bodies have been formed using uniaxial and subsequent isostatic pressure. The resultant coherent samples were subjected to hydrothermal treatment at either 120 or …

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Analysis Of Γ-Irradiated Synthetic Bone Grafts By ²⁹Si Mas-Nmr Spectroscopy, Calorimetry And Xrd, D. Boyd, S. Murphy, Mark R. Towler, A. W. Wren, S. Hayakawa Nov 2009

Analysis Of Γ-Irradiated Synthetic Bone Grafts By ²⁹Si Mas-Nmr Spectroscopy, Calorimetry And Xrd, D. Boyd, S. Murphy, Mark R. Towler, A. W. Wren, S. Hayakawa

Chemical and Biochemical Engineering Faculty Research & Creative Works

Ca-Sr-Zn-Si glasses have demonstrated excellent biocompatibility both in vitro using the MTT assay with L929 mouse fibroblast cells, and in vivo using healthy and ovariectomized female Wistar rats. However, the biological evaluation of the materials was performed on glass granules that were autoclaved, rather than γ-irradiated; the sterilisation procedure required prior to implantation of these materials in the human body. Given the fact that when a glass is exposed to ionizing radiation changes in its physical properties can take place, it is imperative to determine whether the structure of such glasses will be altered as a result of exposure to …

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