Centre for Advanced Imaging Publications - UQ eSpace

Effect of hydrogels or lipoxinA4 on rat periodontal fibroblasts in-vitro

2010-11-08T00:00:00Z

Poly-ethylene-glycol (PEG) based hydrogels have been recognized as a suitable vehicle for the delivery of bioactive molecules. One such bioactive, LipoxinA4 (LXA4) promotes resolution of inflammation and minimizes localised alveolar bone loss in experimentally induced periodontitis. Objective: To evaluate both biodegradable PEG based porous gels (polylactic acid-PEG triblock copolymer; hyperbranched polyester [Boltorn®]-PEG based copolymer; polyhedral oligomeric silsesquioxane [POSS]-PEG based copolymer) and the local effects of three types of gels or LXA4 on the proliferation, viability and cell attachment of rat periodontal fibroblasts. Methods: Biodegradability of PEG based hydrogels were tested in 0.01M phosphate buffer saline, at 37±0.5˚C in incubator. Established primary rat periodontal fibroblast cells (1x104) were used to evaluate the effects of PEG based porous gels and LXA4 on the proliferation (Countess, Invitrogen), viability (LIVE/DEAD® kit, Invitrogen) and cell attachment (confocal microscopy), from 1-5 days in culture. Statistical analysis was done using ANOVA, Bonferroni multiple comparison post tests. Results: All PEG based hydrogels degraded after 28 days. At days 1 and 3, proliferation of POSS treated fibroblasts was significantly lower (p<0.001) compared to the control. At day 5, the viability of POSS treated fibroblasts was significantly reduced compared to day 3 POSS and day 5 Boltorn® treated groups. In LXA4 treated groups, at day 3, proliferation and viability of fibroblasts of 1µg LXA4 and 2µg LXA4 treated groups was significantly lower (p<0.001) than 500ng LXA4 and sham treated groups. However at day 5, fibroblasts cell numbers in 1µg LXA4 and 500ng LXA4 treated groups were significantly higher (p<0.01) compared to 2µg LXA4 and sham treated groups. Confluence and cell attachment of fibroblast cells were significantly diminished on the surface of PEG triblock copolymer treated groups. Conclusion: Low doses of LXA4, PEG triblock or Boltorn®20 copolymers did not inhibit proliferation and attachment of fibroblasts over time. Acknowledgments ADRF and IBRA.

Effect of Iodine Doping on the Electrical Properties of Benzidin Terminated Poly (P-Aminobenzaldehyde) Thin Films

Ghafor, Wael — 2009-02-02T00:00:00Z

Effect of molecular architecture on the performance of (19)F NMR imaging agents

2012-03-06T00:00:00Z

Effect of Motif-Programmed Artificial Proteins on the Calcium Uptake in a Synthetic Hydrogel

2009-11-12T00:00:00Z

Motif-programmed artificial proteins with mineralization-related activity were covalently immobilized onto the surface of a hydrogel, poly(2-hydroxyethyl methacrylate) (PHEMA). We investigated the influence of assaying conditions upon the ability of three selected proteins (PS64, PS382 and PS458) to modulate calcification in vitro. A long-term assay measuring the real amount of calcium phosphate phase in the protein-modified PHEMA showed that all proteins enhanced the uptake of calcium by the hydrogel. For PS382 and PS458, this is a behaviour opposite to that displayed when the same proteins were tested in a free state by a rapid solution assay. Such difference may be attributed to a restricted mobility of the proteins due to immobilization.

Effect of nanoholes on the plasmonic properties of star nanostructures

2012-11-16T00:00:00Z

The transmission and localized electric field distribution of nanostructures are the most important parameters in the plasmonic field for nano-optics and nanobiosensors. In this paper, we propose a novel nanostructure which may be used for nanobiosensor applications. The effect of nanoholes on the plasmonic properties of star nanostructure was studied via numerical simulation, using the finite-difference time-domain (FDTD) method. In the model, the material type and size of the nanostructures was fixed, but the distance between the monotor and the surface of the nanoholes was varied. For example, nanoholes were located in the center of the nanostructures. The simulation method was as follows. Initially, the wavelength of incident light was varied from 400 to 1200 nm and the transmission spectrum and the electric field distribution were simulated. Then at the resonance wavelength (wavelength where the transmission spectrum has a minimum), the localized electric field distribution was calculated at different distances from the surface of the nanostructures. This study shows that the position of nanoholes has a significant effect on the transmission and localized electric field distribution of star nanostructures. The condition for achieving the maximum localized electric field distribution can be used in nano-optics and nanobiosensors in the future.

Effect of osteoporosis on morphology and mobility of the lumbar spine

2009-09-03T08:43:26Z

Effect of solvent quality on the solution properties of assemblies of partially fluorinated amphiphilic diblock copolymers

2012-11-02T11:33:14Z

Effect of splinting and exercise on intraneural edema of the median nerve in carpal tunnel syndrome: An MRI study to reveal therapeutic mechanisms

2012-01-25T08:53:07Z

Effect of temperature and a crosslinking promoter on the gamma-radiolysis of a perfluoroelastomer

2007-08-13T00:00:00Z

Methods of promoting the radiation-induced cross linking of poly(tetrafluoro-ethylene-co-perfluoromethyl vinyl ether) (TFE/PMVE) have been investigated. Greater control of the crosslinking and chain-scission reactions was achieved by varying the radiolysis temperature. This was attributed to temperature affecting the mobilities of reactive species such as polymeric free radicals. These reactive species are precursors to radiation-induced cross links and chain-ends. Analysis of the sol/gel behaviour, tensile properties and FTIR indicated that the optimum temperature for the radiation crosslinking of TFE/PMVE, at a dose of 150 kGy, was 263 K. This temperature was 10 K below the glass transition temperature. Incorporation of 1 wt% triallyl isocyanurate (TAIC) greatly amplified the radiation crosslinking of TFE/PMVE, The dose for gelation was decreased by 70%, and the additive imparted superior mechanical properties compared to the neat irradiated TFE/PMVE. Electron spin resonance (ESR) measurements showed higher radical yields at 77 K with the 1 wt% TAIC, indicating that the crosslinking promoter was acting as a radical trap. (C) 1999 Society of Chemical Industry.

Effect of temperature on the gamma-radiolysis of poly(tetrafluoroethylene-co-perfluoromethyl vinyl ether)

2007-08-13T00:00:00Z

The effect of irradiation temperature on the polymer properties was investigated for the fluoroelastomer poly(tetrafluoroethylene-co-perfluoromethylvinyl ether) (TFE/PMVE). TFE/PMVE samples were gamma-irradiated to 150 kGy at temperatures ranging from 77 K to 373 K. Analysis of the sol/gel behaviour, tensile properties, and glass transition temperatures indicated that crosslinking commenced in the temperature range 195 to 263 K, for a dose of 150 kGy. The latter temperature was 13 K below the glass transition temperature. Crosslinking remained relatively constant to higher temperatures. Chain scission reactions were found to occur well below the glass transition temperature and increased at higher temperatures. The optimum temperature for the radiation crosslinking of TFE/PMVE, for the temperatures investigated, was 263 K. (C) 1998 Elsevier Science Ltd. All rights reserved.

Effects of conformational constraints in cyclic octapeptides of marine origin

2010-07-26T00:00:00Z

Effects of 5-day hypoxia on cardiac adrenergic neurotransmission in rats

2010-11-25T00:00:00Z

Effects of levodopa administration on cerebral functional connectivity

2009-12-09T00:00:00Z

The results are indicative of the striato-cortical and thalamo-cortical connections. Pharmacological modulation with L-dopa seems to enhance connectivity in regions classically associated with attention/vigilance. These results confirm the viability of using fMRI as a marker of pharmacological modulation of functional connectivity

Effects of Levodopa on the neural mechanisms of meaning suppression: A 4T fMRI study

2009-12-09T00:00:00Z

Effects of PtO2 and CeO2 additives on the microstructures of the quenched melts of Y-Ba-Cu-O materials

2008-06-10T12:06:28Z

Effects of streptozotocin-induced diabetes on neural sigma receptors in the rat brain

2010-11-26T00:00:00Z

Effects of thermal denaturation on the solid-state structure and molecular mobility of glycinin

2012-03-14T00:00:00Z

Efficient computer simulation of pulsed electron paramagnetic resonance powder spectra

2008-06-06T00:00:00Z

Electron-beam induced freezing of an aromatic based EUV resist: a robust template for directed self assembly of block copolymers

2012-11-02T00:00:00Z

Resist freezing is routinely used in lithography applications to facilitate double patterning and the directed self assembly (DSA) of block copolymers. Previous reports of graphoepitaxy within patterned positive-tone resists used chemical freezing agents which are known to cause significant shrinkage of critical dimensions (CD). We report the 'freezing' of an aromatic-based EUV resist by exposure to an electron beam, so did not require the use of chemical agents. Crucially, the process did not lead to significant changes in CD and line edge roughness (LER), where the frozen patterns were resistant to treatment with solvents and annealing to temperatures well above the glass transition temperature of the uncrosslinked resist. Finally, we take advantage of these properties and demonstrate the utility of this process for applications in the directed self assembly of block copolymers leading to pattern multiplication.

Electron-beam-induced freezing of a positive tone EUV resist for use in directed self-assembly applications

2011-05-04T00:00:00Z

The commercialization of 32 nm lithography has been made possible by using double patterning, a technique that allows for an increased pattern density, potentially, through resist freezing and high precision pattern registration. Recent developments in directed self assembly (DSA) also uses resist freezing for stabilizing positive tone resists used in graphoepitaxy. We have developed a method of patterning an open source, positive tone EUV resist using electron beam lithography (EBL), and studied a novel way of freezing a positive tone EUV photoresists through electron beam induced crosslinking. Through metrological analysis, crosslinked pattern was observed to retain consistent critical dimensions (CD) and line-edge roughness (LER) after they were annealed at temperatures higher than the glass transition of the photoresist. This process has been used to freeze patterned EUV photoresists, which have been subsequently used for directed self assembly of PS-b-PMMA and has potential applications in double patterning in an LFLE scenario.

Electronic and molecular structure of high-spin d4 complexes: Experimental and theoretical study of the [Cr(D2O)6]2+ cation in Tutton's salts

2010-01-28T00:00:00Z

Variable-temperature spectroscopic and crystallographic studies on the chromium(II) Tutton’s salts, (MI)2Cr(X2O)6(SO4)2, where MI ) ND4+, Rb+, or Cs+, and X ) H or D, are reported. Inelastic neutron scattering (INS) and multifrequency EPR experiments facilitate a rigorous definition of the ground-state electronic structure from 1.5 up to 296 K, which is unprecedented for a high-spin d4 complex. Modeling of the INS data using a conventional S ) 2 spin Hamiltonian reveals a dramatic variation in the axial and rhombic zero-field-splitting parameters. For the ammonium salt, D and E are -2.454(3) and 0.087(3) cm-1 at 10 K and -2.29(2) and 0.16(3) cm-1 at 250 K, respectively. A temperature variation in the stereochemistry of the [Cr(D2O)6]2+ complex is also identified, with an apparent coalescence of the long and medium Cr-O bond lengths at temperatures above 150 K. The corresponding changes for the rubidium and cesium salts are notable, though less pronounced. The experimental quantities are interpreted using a 5EXe Jahn-Teller Hamiltonian, perturbed by anisotropic strain. It is shown that good agreement can be obtained only by employing a model in which the anisotropic strain is itself temperature dependent. A new theoretical approach for calculating variable-temperature EPR spectra of high-spin d4 complexes, developed within the 5EXe coupling model, is described. Differences between spin-Hamiltonian parameters determined by INS and EPR are consistent with those of the different time scales of the two techniques.

Electronic Properties of Thiolate Compounds of Oxomolybdenum (V) and their Tungsten and Selenium Analogues. Effects of 17-O, 98-Mo and 95-Mo Isotope Substitution upon ESR Spectra

2010-07-20T00:00:00Z

Electronic structure and spectro-structural correlations of FeIIIZnII biomimetics for purple acid phosphatases: Relevance to DNA cleavage and cytotoxic activity

2011-01-23T00:00:00Z

Electron paramagnetic resonance

Pilbrow, John R. og Hanson, Graeme R. — 2010-07-20T00:00:00Z

Electron paramagnetic resonance (EPR) and electron spin resonance (ESR) are synonymous terms I for describing the resonant absorption of microwave radiation by a paramagnetic substance in a static magnetic

Electron paramagnetic resonance (EPR) spectroscopic detection of hydroxyl and carbon centered radicals in renal reperfusion injury

2010-07-27T00:00:00Z

Electron paramagnetic resonance spectra of exchange coupled binuclear metalloenzymes and model complexes

2009-04-17T00:00:00Z

Electron paramagnetic resonance studies of a series of biologically relevant copper(II) complexes

2010-07-23T00:00:00Z

Electron paramagnetic resonance studies of nitroxide-annulated phthalocyanines

2010-03-16T00:00:00Z

Electron paramagnetic resonance studies of the [3Fe-4S]1+ cluster in ferredoxin I from G. duodenalis

2010-07-21T00:00:00Z

Electron spin–lattice relaxation of nitroxyl radicals in temperature ranges that span glassy solutions to low-viscosity liquids

2010-01-28T09:02:34Z

Electron spin resonance properties of [MVO(XPh)4]− (M=Mo, W; X=S, Se) species: Effects of 17O, 95Mo and 98Mo isotope substitution

2010-07-26T00:00:00Z

Electron Spin Resonance Study of the Copper (II) and Cobalt (II) Chelates of 2,3;7,8;12,13;17,18-Tetrakis-(9,10-dihydroanthracene-9,10-diyl)porphyrazine

2010-07-20T00:00:00Z

Electron transfer in inorganic, organic, and biological systems

Hanson, G.R. — 2010-07-26T00:00:00Z

Emotional appraisal is influenced by cardiac afferent information

2012-10-23T15:42:12Z

Influential models highlight the central integration of bodily arousal with emotion. Some emotions, notably disgust, are more closely coupled to visceral state than others. Cardiac baroreceptors, activated at systole within each cardiac cycle, provide short-term visceral feedback. Here we explored how phasic baroreceptor activation may alter the appraisal of brief emotional stimuli and consequent cardiovascular reactions. We used functional MRI (fMRI) to measure brain responses to emotional face stimuli presented before and during cardiac systole. We observed that the processing of emotional stimuli was altered by concurrent natural baroreceptor activation. Specifically, facial expressions of disgust were judged as more intense when presented at systole, and rebound heart rate increases were attenuated after expressions of disgust and happiness. Neural activity within prefrontal cortex correlated with emotionality ratings. Activity within periaqueductal gray matter reflected both emotional ratings and their interaction with cardiac timing. Activity within regions including prefrontal and visual cortices correlated with increases in heart rate evoked by the face stimuli, while orbitofrontal activity reflected both evoked heart rate change and its interaction with cardiac timing. Our findings demonstrate that momentary physiological fluctuations in cardiovascular afferent information (1) influence specific emotional judgments, mediated through regions including the periaqueductal gray matter, and (2) shape evoked autonomic responses through engagement of orbitofrontal cortex. Together these findings highlight the close coupling of visceral and emotional processes and identify neural regions mediating bodily state influences on affective judgment.

Emotional modulation of visual cortex activity: a functional near-infrared spectroscopy study

2012-10-30T00:00:00Z

Functional neuroimaging and electroencephalography reveal emotional effects in the early visual cortex. Here, we used functional near-infrared spectroscopy to examine haemodynamic responses evoked by neutral, positive and negative emotional pictures, matched for brightness, contrast, hue, saturation, spatial frequency and entropy. Emotion content modulated amplitude and latency of oxy, deoxy and total haemoglobin response peaks, and induced peripheral autonomic reactions. The processing of positive and negative pictures enhanced haemodynamic response amplitude, and this effect was paralleled by blood pressure changes. The processing of positive pictures was reflected in reduced haemodynamic response peak latency. Together these data suggest that the early visual cortex holds amplitude-dependent representation of stimulus salience and latency-dependent information regarding stimulus valence, providing new insight into affective interaction with sensory processing.

Energy transfer and activated chemiluminescence during thermal oxidation of polypropylene: Evidence for chemically induced electron exchange luminescence

Blakey, I og George, GA og Billingham, NC — 2007-09-19T00:00:00Z

The mechanism of chemiluminescence (CL) during thermal oxidation of polypropylene (PP) was probed by doping PP with an energy acceptor (9,10-dibromoanthracene [DBA]) and a chemiluminescence (CL) activator (9,10-diphenylanthracene [DPA]). Doping PP with DBA had little effect on the shape of the CL intensity (I-CL)-time profile. This suggests that energy transfer from triplet states is probably not significant in the scheme of PP CL. However, the CL activator (DPA) had a significant effect on the shape and intensity of the I-CL-time profile. In the absence of DPA, the I-CL-time profile matches the profile for the formation of carbonyl-containing oxidation products from FTIR-emission spectra. In contrast, in the presence of DPA, it was the integrated DPA I-CL-time profile which snatched the oxidation product profile, indicating that now I-CL was proportional to the hydroperoxide concentration. It is suggested that peroxides formed during PP oxidation are capable of reacting with DPA to produce chemically induced electron exchange luminescence (CIEEL). It is also suggested that CL from undoped PP, i.e., direct CL, may also occur by a CIEEL mechanism. This mechanism is believed to involve the reaction of PP peroxides with an easily oxidizable luminescent oxidation product. For the detector system used in this study the majority of light emitted is consistent with reactions between acyl peroxides and alpha,beta -unsaturated carbonyls. The consequences of this mechanism are that the I-CL-time curve measured during the oxidation of PP may reflect either the hydroperoxide profile or the oxidation product profile depending on the spectral wavelength analyzed or the state of purity of the polymer.

Enhanced human bone marrow stromal cell affinity for modified poly(L-lactide) surfaces by the upregulation of adhesion molecular genes

2010-04-13T00:00:00Z

To enhance and regulate cell affinity for Poly (L-lactic acid) (PLLA) based materials, two hydrophilic ligands, poly (ethylene glycol) (PEG) and poly (L-lysine) (PLL), were used to develop triblock copolymers: methoxy-terminated poly (ethylene glycol)-block-poly (L-lactide)-block-poly (L-lysine) (MPEG-b-PLLA-b-PLL) in order to regulate protein absorption and cell adhesion. Bone marrow stromal cells (BMSCs) were cultured on different composition of MPEG-b-PLLA-b-PLL copolymer films to determine the effect of modified polymer surfaces on BMSC attachment. To understand the molecular mechanism governing the initial cell adhesion on difference polymer surfaces, the mRNA expression of 84 human extracellular matrix (ECM) and adhesion molecules was analysed using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). It was found that down regulation of adhesion molecules was responsible for the impaired BMSC attachment on PLIA surface. MPEG-b-PLLA-b-PLL copolymer films improved significantly the cell adhesion and cytoskeleton expression by upregulation of relevant molecule genes significantly. Six adhesion genes (CDH1, ITGL, NCAM1, SGCE, COL16A1, and LAMA3) were most significantly influenced by the modified PLLA surfaces. In summary, polymer surfaces altered adhesion molecule gene expression of BMSCs, which consequently regulated cell initial attachment on modified PLLA surfaces. (C) 2009 Elsevier Ltd. All rights reserved.

Enhancement of relaxivity rates of Gd-DTPA complexes by intercalation into layered double hydroxide nanoparticles

2008-02-18T16:45:58Z

Environmental complexity and social organization affect visual acuity in African cichlid fishes

2011-03-25T00:00:00Z

The authors studied the effects of habitat complexity and social organization on visual acuity in closely related cichlid fishes (the Ectodini clade). The authors quantified habitat complexity among sand, intermediate, and rock habitats using chromatic difference measures (intensity analysis). Visual acuity was measured behaviorally, using optomotor/optokinetic responses to rotating square-wave stimuli. The rock-dwelling Asprotilapia leptura exhibited the best visual ability, compared with the intermediate and sand-dwelling species, Xenotilapia spilotera and Xenotilapia flavipinnis. The authors then compared effects of social organization. The lek-forming, polygamous Enantiopus melanogenys showed better visual acuity than that of the pair-bonding, monogamous X. flavipinnis. The authors' results are the first to demonstrate that species-specific differences in visual acuity are associated with differences in both the physical and social environment. Copyright 2005 by the American Psychological Association.

Enzymatic polymerizations in supercritical carbon dioxide

2009-01-29T00:00:00Z

Epileptogenesis in experimental models

2011-03-30T00:00:00Z

Epileptogenesis refers to a phenomenon in which the brain undergoes molecular and cellular alterations after a brain-damaging insult, which increase its excitability and eventually lead to the occurrence of recurrent spontaneous seizures. Common epileptogenic factors include traumatic brain injury (TBI), stroke, and cerebral infections. Only a subpopulation of patients with any of these brain insults, however, will develop epilepsy. Thus, there are two great challenges: (1) identifying patients at risk, and (2) preventing and/or modifying the epileptogenic process. Target identification for antiepileptogenic treatments is difficult in humans because patients undergoing epileptogenesis cannot currently be identified. Animal models of epileptogenesis are therefore necessary for scientific progress. Recent advances in the development of experimental models of epileptogenesis have provided tools to investigate the molecular and cellular alterations and their temporal appearance, as well as the epilepsy phenotype after various clinically relevant epileptogenic etiologies, including TBI and stroke. Studying these models will lead to answers to critical questions such as: Do the molecular mechanisms of epileptogenesis depend on the etiology? Is the spectrum of network alterations during epileptogenesis the same after various clinically relevant etiologies? Is the temporal progression of epileptogenesis similar? Work is ongoing, and answers to these questions will facilitate the identification of molecular targets for antiepileptogenic treatments, the design of treatment paradigms, and the determination of whether data from one etiology can be extrapolated to another. © International League Against Epilepsy.

Epoxy functionalised poly(epsilon-caprolactone): Synthesis and application

2010-01-14T14:27:18Z

Glycidol is used as an initiator for ring-opening polymerisation of ε-caprolactone (ε-CL) to synthesise epoxy-functionalised poly(ε-caprolactone) (PCL) in a reaction catalysed by lipase, and the epoxy-functionalised PCL was further copolymerised with carbon dioxide or anhydride to produce novel graft or hyperbranched copolymers. © The Royal Society of Chemistry 2008

EPR and X-ray Crystallographic Studies of Dimethylsulfoxide Reductase from Rhodobacter capsulatus: Implications for Electron Transfer and Catalysis

2010-07-21T00:00:00Z

EPR and X-ray crystallographic studies of dimethylsulfoxide reductase from Rhodobacter capsulatus: Implications for electron transfer and catalysis

2010-07-20T00:00:00Z

EPR Characterisation of the Cr(V) Intermediates in the Cr(VI/V) Oxidations of Organic Substrates and of Relevance to Cr-Induced Cancers

2010-07-22T00:00:00Z

EPR characterisation of the quintet state for a hydrocarbon tetraradical with two localized 1,3-cyclopentanediyl biradicals linked by meta-phenylene as ferromagnetic coupler

2010-07-22T00:00:00Z

EPR evidence for a single electron transfer mechanism in the Mitsunobu esterification reaction

Camp, D. og Hanson, G. R. og Jenkins, I. — 2010-07-26T00:00:00Z

EPR-95, Programme and Abstracts

2010-07-27T00:00:00Z

EPR-95 was a satellite meeting arranged by the Guest Editors to run immediately preceding ISMAR'95 to provide an additional forum for EPR research, given that ISMAR'95 hada very strong NMR bias. EPR-95 was designed to be more of a Workshop on new techniques and participants were encouraged to discuss successes and problems. That was to some extent achieved but as with most conferences these days people generally prefer to present completed work. The attendance was 64 and presentations and posters covered the range from physics through chemistry to biology.

EPR spectroscopy of cobalt(II) and copper(II) encapsulated complexes

2010-07-22T00:00:00Z

A series of structurally well defined cobalt(E) and copper(n) complexes have been prepared... EPR spectroscopy has been employed to monitor the changes in the electronic environment around the cobalt(n) and copper(D) ions present in these encapsulated complexes... Increased tetragonal distortion around the cobalt(II) and copper(JJ) ions are observed as the number of sulfur atoms is increased.

EPR Spectroscopy of Dimethylsulfoxide Reductase from Rhodobacter capsulatus

Hanson, G.R. og Lane, I. og McEwan, A.G. — 2010-07-21T00:00:00Z