Studies of polymeric membranes modified for amperometric H2O2 and pO2 sensing with needle-type electrodes

PhDMaterials used for medical devices are far from ideal for the body, so polymers are applied at the outermost region to counteract the body's natural defences. Component-based failures such as delamination and biocompatibility-based failures such as membrane fouling and degradation still remain a signi cant challenge. This study focuses on the surface properties and modi cation of polyurethane and silicone rubber as coating material for amperometric sensing devices. E ective synthesis of polyurethane, as well as surface modi cation techniques performed on polymers already attached to sensing devices, are proposed. Phase inversion resulted in increased soft segment content on the surface (con rmed by FTIR with a decreased C=O/C=C ratio). It is proposed that such an optimised polymer surface enhances the yield of further surface modi cation, such as hydroxylation (using potassium peroxodisulphate) and sulphonation (employing sodium hydride, triisobutylaluminium and 1,3 propane sultone). A novel method to generate an SO3-derivatised PU surface was proposed. Additionally, successful synthesis of silicone rubber for induced permeability of H2O2 was demonstrated. The physical and chemical properties of these modi ed polymers were examined and evaluated via FTIR, SEM, TGA and contact angle measurements. The biocompatibility of modi ed polymers was con rmed with retarded protein adsorption; cytotoxicity testing showed that polymers were non-toxic to cells. Steady state amperometry on polymer modi ed needle-type electrodes showed enhanced performance with surface modi ed polymers to oxygen and H2O2, both of which are potential biological assay targets. Synthesised Prussian Blue (redox mediator) on platinum surfaces showed that the electrochemical response to H2O2 was increased threefold; and in combination with sulphonated polyurethane, interfering current responses could be successfully eliminated

The lock-in phase in the urotropine-sebacic acid system

The 1,10-decanedioic acid-1,3,5,7-tetraazatricyclo[3.3.1.1(3,7)]decane (1/1) system, C10H18O4.C6H12N4, was studied at 215 (2) K. Its analysis provides important information with regard to the long-standing acid-carboxylate controversy in the urotropine-alkanedioic acid system. In the present structure, all the chain end-groups display a clear acid character. The asymmetric unit of this commensurate modulated phase contains two molecules of diacid as well as two molecules of urotropine. Furthermore, the chain packing suggests a possible order parameter for the lock-in transition

Electrode and chemical reactions during electrodeposition of tantalum products in CsCl melt

This work was accomplished in the context of systematic examination of a role played by electrolyte cation composition in electroreduction processes. The electrochemical behaviour of molten salts systems where CsCl was used as solvent for potassium and caesium oxyfluorotantalates was investigated. In particular, the influence of the electrolysis parameters, such as concentration of tantalum species in electrolyte, temperature and current density on the cathodic products phase composition was determined by X-ray diffraction and scanning electron microscopy. Several phases generally crystallized at the cathode simultaneously. Among identified phases were metallic tantalum in cubic ($\alpha$) and tetragonal (β) crystal modifications and TaO. But the most characteristic phases for the melt under study were two isostructural compounds with pyrochlor type crystal lattice CsTa$_{2+z}^5$O$_{5+y}$F$_{1-y}$ and CsTa$_{2+z}^{5- x}$O$_{5+y}$F$_{1-y}$. The former deposited in the form of transparent dielectric crystals and the later – in the form of metal-like conductive ones. This latter compound seems to be synthesized for the first time. The peculiarities of its structure were described. Electrochemical redox processes in melts containing potassium oxyfluorotantalates dissolved in CsCl were studied by cyclic voltammetry. Three discharge peaks were detected on voltammograms in the temperature range 700-850 $^\circ$C. They were associated with the discharge of TaOF$_6^{3-}$ and TaO$_2$F$_4^{3-}$ complexes and alkali metal cations

Optomechanical interactions in non-Hermitian photonic molecules

© 2016 OSA. We investigate optomechanical interactions in non-Hermitian photonic molecules. We show that the maximum enhancement of optomechanical coupling for steady state solutions is achieved for unbalanced gain and loss profiles away from exceptional points

The tracking detector of the KLOE experiment

The design and construction of the large Drift Chamber for the KLOE experiment at the Frascati f-factory, DAFNE; are described. The relevant aspects of the various elements of the detector are reviewed together with a description of the track reconstruction program and of the calibration procedures. The performance of the detector based on measurements with cosmic rays and with eþe colliding beams during DAFNE commissioning is presented

The tracking detector of the KLOE experiment

The design and construction of the large Drift Chamber for the KLOE experiment at the Frascati phi-factory, DAPhiNE, are described. The relevant aspects of the various elements of the detector are reviewed together with a description of the track reconstruction program and of the calibration procedures. The performance of the detector based on measurements with cosmic rays and with e(-)e(-) colliding beams during DAPhiNE commissioning is presented