A5082611241- Metal and Thin Film Mechanics
- Diamond and Carbon-based Materials Research
- Tribology and Wear Analysis
- Additive Manufacturing and 3D Printing Technologies
- Mechanical Circulatory Support Devices
- Polymer Nanocomposite Synthesis and Irradiation
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Electrospun Nanofibers in Biomedical Applications
- Dental materials and restorations
- Nitric Oxide and Endothelin Effects
- Lubricants and Their Additives
- Advanced Sensor and Energy Harvesting Materials
- Cardiac Ischemia and Reperfusion
- Cardiac Structural Anomalies and Repair
- Radical Photochemical Reactions
- Bone Tissue Engineering Materials
- Molecular spectroscopy and chirality
- Fuel Cells and Related Materials
- Literacy, Media, and Education
- Adhesion, Friction, and Surface Interactions
- Photoreceptor and optogenetics research
- Orthopaedic implants and arthroplasty
- Transplantation: Methods and Outcomes
- Neuroscience and Neural Engineering
University of Nairobi
2022
UNSW Sydney
1990-2021
University of Warwick
2011-2016
The University of Sydney
1989-2015
Cochlear (Australia)
2010-2014
Macquarie University
2011-2014
Coventry University
2013
Landcare Australia
2005-2007
Georgia Institute of Technology
1996
Emory University
1995-1996
Endothelial cells release nitric oxide (NO) more potently in response to increased shear stress than agonists which elevate intracellular free calcium concentration ([Ca 2+ ] i ). To determine mechanistic differences the regulation of endothelial constitutive NO synthase (ecNOS), we measured production by bovine aortic exposed a laminar flow chamber or treated with Ca ionophores static culture. The kinetics cumulative varied strikingly: (25 dyne/cm 2 ) stimulated biphasic increase over...
The effect of extracellular L-arginine and L-glutamine on nitric oxide (NO) release was studied in cultured bovine aortic endothelial cells rabbit rings. Increasing (0.01 to 10 mM) did not alter NO from or modify endothelium-dependent relaxation acetylcholine isolated vessels. L-Glutamine (0.6 2 inhibited (in response bradykinin) rings ADP). L-Arginine (0.1-10 dose-dependently reversed the inhibition receptor-stimulated both models. In contrast its inhibitory receptor-mediated stimuli,...
Abstract Polyetheretherketone (PEEK) is an attractive material for the encapsulation of active medical implants. PEEK, however, shows hydrophobic surface properties which are not favorable protein absorption and cell adhesion. We show that oxygen rich nanofilms “sticky thin film,” deposited on PEEK surfaces from plasma using a immersion ion implantation deposition technique with (CH 4 /O 2 ) gas mixture greatly improved adhesion (up to 75%) spreading 81%). Strong correlations were found...
The barrier to rotation around the N-alkenyl bond of 38 N-alkenyl-N-alkylacetamide derivatives was measured (ΔG(⧧) varied between <8.0 and 31.0 kcal mol(-1)). most important factor in controlling rate level alkene substitution, followed by size nitrogen substituent and, finally, acyl substituent. Tertiary enamides with four alkenyl substituents exhibited half-lives for 5.5 days 99 years at 298 K, sufficient isolate enantiomerically enriched atropisomers. radical cyclizations a subset...
The purpose of this study was to char-acterize the effect various shear conditions on endothelial cell intracellular calcium ([Ca2+]i). Bovine aortic cells (BAEC) were loaded with Fluo-3 and exposed flow in a parallel plate chamber designed for confocal microscopy. medium 199 (M-199), which prepared without adenosine triphosphate (ATP). In presence ATP, initiation at stress 2.5 dyn/cm2 evoked strong, sustained elevation [Ca2+]i that gradually returned baseline levels over 10 15 min. By...
Abstract High performance polymers such as PEEK are currently considered unsuitable for the encapsulation of biomedical implants, partly because a lack strong and durable bonding technology. Strong autohesive bonds were achieved between semi‐crystalline surfaces using treatment in RF plasma with mixture methane oxygen (CH 4 /O 2 ) gases. The bonded under pressure above glass transition temperature ( T g below melting point m ). CH gases produced significantly higher bond strength than...
Abstract: The VentrAssist implantable rotary blood pump (IRBP) is an centrifugal with a hydrodynamically suspended impeller; optimal efficiency requires small running clearances (70–300 μm). effect of clearance and polish on hemolysis was evaluated in vitro. Three different human suspensions were compared: phosphate buffered saline (PBS), plasma volume expander (Hemaccel), whole blood. test conditions were: hematocrit 30%, flow rate 5 L/min, pressure across 100 mm Hg, 6 h period, 37°C....
Abstract Polyether ether ketone (PEEK) is a promising material for the encapsulation of electronic components medical implants but strong and hermetic joining technology required. Autohesion self‐bonding method that avoids need adhesives. The strengths autohesive joins using amorphous semi‐crystalline PEEK films after surface activation RF plasma were compared. Both types showed successful autohesion with bond strength sample being twice as high sample. Plasma treatment increased no observed...
An optical fiber-based sensor has been developed to measure the forces at tip of an electrode array during insertion into cochlea. The sensor, utilizing fiber Bragg grating technology, was incorporated a custom-designed Pt-banded for guinea pigs. In vivo experiments were undertaken in which measured real time insertion. Data obtained maximum up 254 mN. Histology performed on excised cochleae with sensors fixed position evaluate level trauma. demonstrated clear correlation between applied...
The 4-exo and 5-exo-trig atom-transfer cyclizations of 1, 8a–e, 9, 12, 13 can be mediated with as little 0.05 mol % Cu(TPMA)SO4·5H2O in the presence 2.5 borohydride salts 10 min at room temperature air. This formal "activators generated by electron transfer" (AGET) procedure utilizes a cheap oxidatively stable copper source (CuSO4·5H2O) carried out environmentally benign solvents (EtOH). It is possible to alter product distribution 5-endo radical–polar crossover reactions 10a,b 11 tailoring...
Abstract: This study examines, under flow conditions, the adhesion of endothelial cells to 3 mm diameter fi‐bronectin (Fn)‐coated expanded polytetrafluoroethylene (PTFE) vascular grafts. Cultured ovine carotid artery were labelled with 35S‐methionine. The grafts seeded (1.5 times 106/ml) by rolling for 1 h at 37d̀C and then either cultured confluence 48 or tested immediately. Cell attachment (n = 5) was evaluated in an vitro circuit, using flows up 330 ml/min. Ex vivo studies 5 grafts)...
Abstract Polyether ether ketone (PEEK) and its composites have emerged as one of the main candidate materials for replacing titanium alloys encapsulating components medical implants. PEEK, however, is a difficult material to bond without use adhesion promoting agents. Experiments based on central composite rotatable design (CCRD) were used find an optimum plasma surface modification treatment. X‐ray photoelectron spectrometry (XPS), contact angle measurements scanning electron microscopy...
Abstract Thin films of polyetheretherketone (PEEK) were ion bombarded using a plasma immersion implantation (PIII) process in Ar and CH 4 /O 2 plasmas. Free radicals generated by the treatment detected electron spin resonance (ESR) spectroscopy. Several types observed after PIII treatment, including carbon‐centred (alkyl) oxygen‐centred radicals. A higher density was found than largely because an increase oxygen The radical intensity attributed partly to additional contained nano‐layer...
Barriers to rotation of the N-alkenyl bond in a series N-cycloalkenyl-N-benzyl acetamide derivatives have been measured different solvents by variable-temperature NMR experiments. The barriers range from 9.7 14.2 kcal/mol, depending on substituents acyl group. Polar such as chloroform and methanol increase barrier compared nonpolar toluene. "mimics" for acetamide-based radicals are estimated. relative order values k(rot) groups parallels their reported Taft E(s) paramaters. For successful...
We find that plasma immersion ion implantation of polymer surfaces enhances their autohesive bond strength when pressed together by more than a factor five. Both polymerising (CH4/O2) and nonpolymerising (Ar) plasmas are effective. There is currently no satisfactory theory for predicting this remarkable phenomenon. propose free radicals created the treatment process diffuse to interface cause covalent bonds form. This predicts dependence on bias voltage, time, conditions.
Severe visual impairment can result from retinal degenerative diseases such as retinitis pigmentosa, which lead to photoreceptor cell death. These pathologies in extensive neural and glial remodelling, with survival of excitable neurons that be electrically stimulated elicit percepts restore a form useful vision. The Phoenix99 Bionic Eye is fully implantable prosthesis, designed stimulate the retina suprachoroidal space. In current study, nine passive devices were implanted an ovine model...