A Bond | University of East Anglia (original) (raw)
Papers by A Bond
We are very interested to receive comments on this HIA review package. Please send comments to hi... more We are very interested to receive comments on this HIA review package. Please send comments to hiareview@bcahealth.co.uk Ben Cave Associates Ltd is a specialist consultancy for public health and sustainability. Since 2001 we have worked with the public, the private and the community and voluntary sectors across England and in Europe. We conduct impact assessment and research, we provide training and policy analysis. We have a strong commitment to quality, to sharing knowledge and to the power of collective and creative input.
Impact Assessment and Project Appraisal, 2004
This report describes the results of experiments designed to evaluate the suitability of using co... more This report describes the results of experiments designed to evaluate the suitability of using conventional crushing equipment for the crush, burn, leach concept of HTGR head-end fuel reprocessing. Under this concept, fuel elements are crushed to ring-size particles smaller than 3/16 in. (4.8 mm) while minimizing the breakage of TRISO-coated fuel particles. Conventional equipment has been evaluated for the primary
Analytical chemistry, Jan 26, 2015
The concept of using an internal reversible reference process as a calibration in the determinati... more The concept of using an internal reversible reference process as a calibration in the determination of fast electrode kinetics has been developed and applied with the technique of Fourier transformed large amplitude AC voltammetry to minimize the influence of errors arising from uncertainties in parameters such as electrode area (A), concentration (C), diffusion coefficient (D) and uncompensated resistance (Ru). Since kinetic parameters (electron transfer rate constant, k0, and electron transfer coefficient, α) are irrelevant in the voltammetric characterisation of a reversible reaction, parameters such as A, C, D and Ru can calibrated using the reversible process prior to quantification of the electrode kinetics associated with the fast quasi-reversible process. If required, new values of parameters derived from the calibration exercise can be used for the final determination of k0 and α associated with the process of interest through theory-experimental comparison exercises. Refer...
ACS applied materials & interfaces, Jan 9, 2015
A method has been developed for the efficient electrodeposition of cobalt and nickel nanostructur... more A method has been developed for the efficient electrodeposition of cobalt and nickel nanostructures with the assistance of the Lindqvist ion [Nb6O19]8-. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectrometry and a range of electrochemical techniques have been used to characterize the morphology, composition, catalytic water oxidation activity and stability of the films in alkaline solution. SEM images show that films consisting of nanoparticles with diameters of ca 30 to 40 nm are formed after 40 to 50 potential cycles of deposition. Nb and Co/Ni are detected in the films by EDX. ICP-MS results show an elemental ratio of 1:1 for Co:Nb and 1:3 for Ni:Nb, respectively. Raman spectra reveal the presence of both [Nb6O19]8- and Co(OH)2/Ni(OH)2. The films exhibit excellent stability and efficiency for electrocatalytic water oxidation ...
Inorganic Chemistry, 2007
The synthesis of new zirconium and hafnium mixed ligand phthalocyanine complexes PcM(b-ketoester)... more The synthesis of new zirconium and hafnium mixed ligand phthalocyanine complexes PcM(b-ketoester) 2 , where M-Zr (IV), Hf (IV); Pc -the dianion of phthalocyanine, and b-ketoester -the out planed ligand, is reported. The obtained complexes are characterized by 1 H NMR, IR, UV-Vis spectroscopy and cyclic voltammetry. 1 H NMR and elemental analysis confirm the substitution of two Cl atoms for two b-ketoester fragments to the central atom of the macrocycle. The data of 1 H NMR, UV-Vis spectroscopy have allowed us to conclude that two b-ketoester ligands are in the cis geometry to the phthalocyanine plane. X-ray crystallography for bis(isopropyl 3-oxobutanoato)hafnium(IV)phthalocyanine confirms this conclusion. The central macrocycle of the phthalocyanine ligand is not exactly planar (deviations from the least-square plane exceed 0.15 Å ) and has the conformation of an essentially flattened crown. The Hf(1) atom is 1.349(3) above this least-square plane. Cyclic voltammetry investigation shows that the introduction of two b-ketoester ligands to the central atom of phthalocyanine complex leads to both chemical and electrochemical stabilization of the whole Pc system.
Langmuir, 2008
... An accurate measure of the water contribution to the Δf N value is difficult to obtain. ... (... more ... An accurate measure of the water contribution to the Δf N value is difficult to obtain. ... (29) Laviron, E. In Electronanalytical Chemistry; Bard, AJ, Ed.; Marcel Dekker: New York, 1982; Vol. 12, pp 53−157. Laviron, E. J. Electroanal. Chem.1979, 101, 19−28. ...
![Research paper thumbnail of Morphology Changes and Mechanistic Aspects of the Electrochemically-Induced Reversible Solid−Solid Transformation of Microcrystalline TCNQ into Co[TCNQ] 2 Based Materials (TCNQ = 7,7,8,8-Tetracyanoquinodimethane)](https://attachments.academia-assets.com/43782604/thumbnails/1.jpg)
](Chemistry of Materials, 2006
The chemically reversible solid-solid phase transformation of a TCNQ-modified glassy carbon, indi... more The chemically reversible solid-solid phase transformation of a TCNQ-modified glassy carbon, indium tin oxide, or metal electrode into Co[TCNQ] 2 (H 2 O) 2 material in the presence of Co 2+ (aq) containing electrolytes has been induced and monitored electrochemically. Voltammetric data reveal that the TCNQ/ Co[TCNQ] 2 (H 2 O) 2 interconversion process is independent of electrode material and identity of cobalt electrolyte anion. However, a marked dependence on electrolyte concentration, scan rate, and method of electrode modification (drop casting or mechanical attachment) is found. Cyclic voltammetric and double potential step chronoamperometric measurements confirm that formation of Co[TCNQ] 2 (H 2 O) 2 occurs through a rate-determining nucleation and growth process that initially involves incorporation of Co 2+ (aq) ions into the reduced TCNQ crystal lattice at the TCNQ|electrode|electrolyte interface. Similarly, the reverse (oxidation) process, which involves transformation of solid Co[TCNQ] 2 (H 2 O) 2 back to parent TCNQ crystals, also is controlled by nucleation-growth kinetics. The overall chemically reversible process that represents this transformation is described by the reaction: (s) . Ex situ SEM images illustrated that this reversible TCNQ/Co[TCNQ] 2 (H 2 O) 2 conversion process is accompanied by drastic size and morphology changes in the parent solid TCNQ. In addition, different sizes of needle-shaped nanorod/nanowire crystals of Co[TCNQ] 2 (H 2 O) 2 are formed depending on the method of surface immobilization.
Journal of The American Chemical Society, 2007
A generic method for the synthesis of metal-7,7,8,8-tetracyanoquinodimethane (TCNQ) chargetransfe... more A generic method for the synthesis of metal-7,7,8,8-tetracyanoquinodimethane (TCNQ) chargetransfer complexes on both conducting and nonconducting substrates is achieved by photoexcitation of TCNQ in acetonitrile in the presence of a sacrificial electron donor and the relevant metal cation. The photochemical reaction leads to reduction of TCNQ to the TCNQmonoanion. In the presence of M x+ (MeCN), reaction with TCNQ -(MeCN) leads to deposition of M x+ [TCNQ]x crystals onto a solid substrate with morphologies that are dependent on the metal cation. Thus, CuTCNQ phase I photocrystallizes as uniform microrods, KTCNQ as microrods with a random size distribution, AgTCNQ as very long nanowires up to 30 µm in length and with diameters of less than 180 nm, and Co[TCNQ]2(H2O)2 as nanorods and wires. The described charge-transfer complexes have been characterized by optical and scanning electron microscopy and IR and Raman spectroscopy. The CuTCNQ and AgTCNQ complexes are of particular interest for use in memory storage and switching devices. In principle, this simple technique can be employed to generate all classes of metal-TCNQ complexes and opens up the possibility to pattern them in a controlled manner on any type of substrate.
Journal of Physical Chemistry B, 2009
The preparation and characterization of a series of ionic liquids based on S-alkyl thiolonium, S-... more The preparation and characterization of a series of ionic liquids based on S-alkyl thiolonium, S-alkyl thiotetrazolium, or S-alkyl thiobenzolium cations coupled with bis(trifluoromethanesulfonyl)amide, trifluoromethanesulfonate, alkyl phosphate, chloride, and hexafluorophosphate anions are reported. All are liquid at room temperature, except the chloride salt, which has a melting point of 92 degrees C. The electrochemical characteristics of this class of ionic liquid have been determined by cyclic voltammetry. Potential windows of the ionic liquids have been obtained at glassy carbon, platinum, and gold electrodes and found to be the largest at glassy carbon, but are limited by oxidation of the thioether-functionalized cation. The voltammetry of IUPAC reference potential scale systems, ferrocene/ferrocenium, cobaltocenium/cobaltocene, and decamethylferrocene/decamethylferrocenium have been evaluated, with the last being most widely applicable. Nonadditivity of Faradaic current is found in the voltammograms of decamethylferrocene in the presence of ferrocene and cobaltocenium. Diffusion coefficient, viscosity, ionic conductivity, double layer capacitance, and other physical properties have also been measured. The dependence of the diffusion coefficient vs viscosity follows the Stokes-Einstein relationship. The properties of the ionic liquids are compared with the related imidazolium family of ionic liquids.
Journal of The American Chemical Society, 2009
Unexpected nonadditivity of currents encountered in the electrochemistry of mixtures of ferrocene... more Unexpected nonadditivity of currents encountered in the electrochemistry of mixtures of ferrocene (Fc) and cobaltocenium cation (Cc + ) as the PF 6salt has been investigated by direct current (dc) and Fourier-transformed alternating current (ac) cyclic voltammetry in two aprotic (1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate) and three protic (triethylammonium formate, bis(2-hydroxyethyl)ammonium acetate, and triethylammonium acetate) ionic liquids (ILs). The voltammetry of the individual Fc 0/+ and Cc +/0 couples always exhibits near-Nernstian behavior at glassy carbon and gold electrodes. As expected for an ideal process, the reversible formal potentials and diffusion coefficients at 23 ( 1°C in each IL determined from measurement on individual Fc and Cc + solutions were found to be independent of electrode material, concentration, and technique used for the measurement. However, when Fc and Cc + were simultaneously present, the dc and ac peak currents per unit concentration for the Fc 0/+ and Cc +/0 processes were found to be significantly enhanced in both aprotic and protic ILs. Thus, the apparent diffusion coefficient values calculated for Fc and Cc + were respectively found to be about 25 and 35% larger than those determined individually in the aprotic ILs. A similar change in the Fc 0/+ mass transport characteristics was observed upon addition of tetrabutylammonium hexafluorophosphate (Bu 4 NPF 6 ), and the double layer capacitance also varied in distinctly different ways when Fc and Cc + were present individually or in mixtures. Importantly, the nonadditivity of Faradaic current is not associated with a change in viscosity or from electron exchange as found when some solutes are added to ILs. The observation that the 1 H NMR T 1 relaxation times for the proton resonance in Cc + also are modified in mixed systems implies that specific interaction with aggregates of the constituent IL ionic species giving rise to subtle structural changes plays an important role in modifying the mass transport, double layer characteristics, and dynamics when solutes of interest in this study are added to ILs. Analogous voltammetric changes were not observed in studies in organic solvent media containing 0.1 M added supporting electrolyte. Implications of the nonadditivity of Faradaic and capacitance terms in ILs are considered.
Chemistry of Materials, 2007
Chemically synthesized AgTCNQ exists in two forms that differ in their morphologies (needles and ... more Chemically synthesized AgTCNQ exists in two forms that differ in their morphologies (needles and microcrystals) and colors (red and blue). It is now shown that both forms exhibit essentially indistinguishable X-ray diffraction, spectroscopic, and thermochemical data, implying that they are not separate phases, as implied in some literature. Electrochemical reduction of TCNQ (MeCN) in the presence of Ag + (MeCN) generates both red and blue AgTCNQ. On glassy carbon, platinum, or indium tin oxide electrodes and at relatively positive deposition potentials, slow growth of high aspect ratio, red needle AgTCNQ crystals occurs. After longer times and at more negative deposition potentials, blue microcrystalline AgTCNQ thin films are favored. Blue AgTCNQ is postulated to be generated via reduction of a Ag + [(TCNQ •-)(TCNQ)] (MeCN) intermediate. At even more negative potentials, Ag (metal) formation inhibits further growth of AgTCNQ. On a gold electrode, Ag (metal) deposition occurs at more positive potentials than on the other electrode materials examined. However, surface plasmon resonance data indicate that a small potential region is available between the stripping of Ag (metal) and the oxidation of TCNQ •-(MeCN) back to TCNQ (MeCN) where AgTCNQ may form. AgTCNQ in both the red and blue forms also can be prepared electrochemically on a TCNQ (s) modified electrode in 0.1 M AgNO 3(aq) where deposition of Ag (metal) onto the TCNQ (s) crystals allows a charge transfer process to occur. However, the morphology formed in this solid-solid phase transformation is more difficult to control.
International Journal of Gynecology & Obstetrics, 1987
In a community survey 521 women aged 35-59 were selected at random from all patients registered i... more In a community survey 521 women aged 35-59 were selected at random from all patients registered in two groups practices. They were interviewed at home and assessed by means of standardised psychiatric measures and detailed gynaecological inquiry. Levels of psychiatric morbidity were found to be within the expected range for such a sample. Both psychiatric morbidity and the personality dimension
Langmuir : the ACS journal of surfaces and colloids, Jan 8, 2015
Commonly, significant discrepancies are reported in theoretical and experimental comparisons of D... more Commonly, significant discrepancies are reported in theoretical and experimental comparisons of DC voltammograms derived from a monolayer or close to monolayer coverage of redox active surface-confined molecules. For example, broader than predicted voltammetric wave shapes are attributed to thermodynamic or kinetic dispersion derived from distributions in reversible potentials ($E^0$) and electrode kinetics ($k^0$), respectively. Recent availability of experimentally estimated distributions of E0E^0E0 and k0k^0k0 values derived from analysis of data for small numbers of surface-confined modified azurin metalloprotein molecules now allow more realistic modelling to be undertaken, assuming the same distributions apply under conditions of high surface coverage relevant to voltammetric experiments. In this work, modelling based on conventional and stochastic kinetic theory is considered, and the computationally far more efficient conventional model is shown to be equivalent to the stochasti...
Journal of experimental psychology. Animal learning and cognition, 2014
Visual search for complex natural targets requires focal attention, either cued by predictive sti... more Visual search for complex natural targets requires focal attention, either cued by predictive stimulus associations or primed by a representation of the most recently detected target. Because both processes can focus visual attention, cuing and priming were compared in an operant search task to evaluate their relative impacts on performance and to determine the nature of their interaction in combined treatments. Blue jays were trained to search for pairs of alternative targets among distractors. Informative or ambiguous color cues were provided before each trial, and targets were presented either in homogeneous blocked sequences or in constrained random order. Initial task acquisition was facilitated by priming in general, but was significantly retarded when targets were both cued and primed, indicating that the two processes interfered with each other during training. At asymptote, attentional effects were manifested mainly in inhibition, increasing latency in miscued trials and de...
International journal of sports medicine, 1998
The purpose of this study was to compare blood markers associated with eccentrically biased exerc... more The purpose of this study was to compare blood markers associated with eccentrically biased exercise and muscle damage, after two bouts of downhill running. Nine active, untrained males performed 2 x 45 min bouts of downhill running (-0.16 radians), at a speed that would elicit 70% of each subjects VO2max, on a level grade; runs were spaced 14d apart (RUN1, RUN2). Blood samples were obtained before, after, and every hour for 12 h after exercise, as well as every 24 h for 5 d, to assess numbers of circulating neutrophils, monocytes, and lymphocytes, serum cortisol, creatine kinase (CK); subjective sensations of delayed onset muscle soreness (DOMS) were monitored. To control for diurnal variation, two weeks prior to the RUN1, subjects had blood draws performed at the same time as would occur after exercise, but did no exercise (CONTROL). During the 5 d after exercise, DOMS and CK were significantly greater (p < 0.05) after RUN1 compared to RUN2 and CONTROL. During the 12 h after RU...
The electrochemical oxidation of cobalt(III) dithiocarbamates and diselenocarbamates (CoL 3 ) in ... more The electrochemical oxidation of cobalt(III) dithiocarbamates and diselenocarbamates (CoL 3 ) in acetonitrile + 0.1 M Bu 4 NPF 6 is shown to occur via the mechanism: (E) CoL 3 l[CoL 3 ] + + e − ; (C 2 ) 2[CoL 3 ] + [Co 2 L 5 ] + + oxidized ligand; (C) [Co 2 L 5 ] + + 2CH 3 CN CoL 3 +[CoL 2 (CH 3 CN) 2 ] + . A combination of electrochemical, electrospray mass spectrometry, and 59 Co/ 77 Se NMR experiments confirms that the binuclear species, [Co 2 L 5 ] + , reacts with acetonitrile forming CoL 3 and [CoL 2 (CH 3 CN) 2 ] + . At the electrode surface, CoL 3 species generated by this reaction may then be reoxidised resulting in an enhanced peak or limiting current. Consequently, the oxidation of CoL 3 in acetonitrile represents an overall EC 2 C mechanism. The data obtained from cyclic voltammetry at Pt disc electrodes and steady-state hydrodynamic voltammetry at platinum channel electrodes for oxidation of CoL 3 were modelled according to this EC 2 C scheme using the commercial DigiSim electrochemical simulation package and the backwards implicit finite difference technique, respectively. Good fits between experiment and simulation were obtained using the same kinetic parameters for both methods. The calculated dimerisation rate constant (C 2 step) is similar to the value obtained in dichloromethane, which is uncomplicated by reaction of [Co 2 L 5 ] + with the solvent. It was observed that if either voltammetric technique was used in isolation, a wider range of combinations of kinetic parameters could be utilised in order to obtain satisfactory fits between experiment and theory.
We are very interested to receive comments on this HIA review package. Please send comments to hi... more We are very interested to receive comments on this HIA review package. Please send comments to hiareview@bcahealth.co.uk Ben Cave Associates Ltd is a specialist consultancy for public health and sustainability. Since 2001 we have worked with the public, the private and the community and voluntary sectors across England and in Europe. We conduct impact assessment and research, we provide training and policy analysis. We have a strong commitment to quality, to sharing knowledge and to the power of collective and creative input.
Impact Assessment and Project Appraisal, 2004
This report describes the results of experiments designed to evaluate the suitability of using co... more This report describes the results of experiments designed to evaluate the suitability of using conventional crushing equipment for the crush, burn, leach concept of HTGR head-end fuel reprocessing. Under this concept, fuel elements are crushed to ring-size particles smaller than 3/16 in. (4.8 mm) while minimizing the breakage of TRISO-coated fuel particles. Conventional equipment has been evaluated for the primary
Analytical chemistry, Jan 26, 2015
The concept of using an internal reversible reference process as a calibration in the determinati... more The concept of using an internal reversible reference process as a calibration in the determination of fast electrode kinetics has been developed and applied with the technique of Fourier transformed large amplitude AC voltammetry to minimize the influence of errors arising from uncertainties in parameters such as electrode area (A), concentration (C), diffusion coefficient (D) and uncompensated resistance (Ru). Since kinetic parameters (electron transfer rate constant, k0, and electron transfer coefficient, α) are irrelevant in the voltammetric characterisation of a reversible reaction, parameters such as A, C, D and Ru can calibrated using the reversible process prior to quantification of the electrode kinetics associated with the fast quasi-reversible process. If required, new values of parameters derived from the calibration exercise can be used for the final determination of k0 and α associated with the process of interest through theory-experimental comparison exercises. Refer...
ACS applied materials & interfaces, Jan 9, 2015
A method has been developed for the efficient electrodeposition of cobalt and nickel nanostructur... more A method has been developed for the efficient electrodeposition of cobalt and nickel nanostructures with the assistance of the Lindqvist ion [Nb6O19]8-. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectrometry and a range of electrochemical techniques have been used to characterize the morphology, composition, catalytic water oxidation activity and stability of the films in alkaline solution. SEM images show that films consisting of nanoparticles with diameters of ca 30 to 40 nm are formed after 40 to 50 potential cycles of deposition. Nb and Co/Ni are detected in the films by EDX. ICP-MS results show an elemental ratio of 1:1 for Co:Nb and 1:3 for Ni:Nb, respectively. Raman spectra reveal the presence of both [Nb6O19]8- and Co(OH)2/Ni(OH)2. The films exhibit excellent stability and efficiency for electrocatalytic water oxidation ...
Inorganic Chemistry, 2007
The synthesis of new zirconium and hafnium mixed ligand phthalocyanine complexes PcM(b-ketoester)... more The synthesis of new zirconium and hafnium mixed ligand phthalocyanine complexes PcM(b-ketoester) 2 , where M-Zr (IV), Hf (IV); Pc -the dianion of phthalocyanine, and b-ketoester -the out planed ligand, is reported. The obtained complexes are characterized by 1 H NMR, IR, UV-Vis spectroscopy and cyclic voltammetry. 1 H NMR and elemental analysis confirm the substitution of two Cl atoms for two b-ketoester fragments to the central atom of the macrocycle. The data of 1 H NMR, UV-Vis spectroscopy have allowed us to conclude that two b-ketoester ligands are in the cis geometry to the phthalocyanine plane. X-ray crystallography for bis(isopropyl 3-oxobutanoato)hafnium(IV)phthalocyanine confirms this conclusion. The central macrocycle of the phthalocyanine ligand is not exactly planar (deviations from the least-square plane exceed 0.15 Å ) and has the conformation of an essentially flattened crown. The Hf(1) atom is 1.349(3) above this least-square plane. Cyclic voltammetry investigation shows that the introduction of two b-ketoester ligands to the central atom of phthalocyanine complex leads to both chemical and electrochemical stabilization of the whole Pc system.
Langmuir, 2008
... An accurate measure of the water contribution to the Δf N value is difficult to obtain. ... (... more ... An accurate measure of the water contribution to the Δf N value is difficult to obtain. ... (29) Laviron, E. In Electronanalytical Chemistry; Bard, AJ, Ed.; Marcel Dekker: New York, 1982; Vol. 12, pp 53−157. Laviron, E. J. Electroanal. Chem.1979, 101, 19−28. ...
Chemistry of Materials, 2006
The chemically reversible solid-solid phase transformation of a TCNQ-modified glassy carbon, indi... more The chemically reversible solid-solid phase transformation of a TCNQ-modified glassy carbon, indium tin oxide, or metal electrode into Co[TCNQ] 2 (H 2 O) 2 material in the presence of Co 2+ (aq) containing electrolytes has been induced and monitored electrochemically. Voltammetric data reveal that the TCNQ/ Co[TCNQ] 2 (H 2 O) 2 interconversion process is independent of electrode material and identity of cobalt electrolyte anion. However, a marked dependence on electrolyte concentration, scan rate, and method of electrode modification (drop casting or mechanical attachment) is found. Cyclic voltammetric and double potential step chronoamperometric measurements confirm that formation of Co[TCNQ] 2 (H 2 O) 2 occurs through a rate-determining nucleation and growth process that initially involves incorporation of Co 2+ (aq) ions into the reduced TCNQ crystal lattice at the TCNQ|electrode|electrolyte interface. Similarly, the reverse (oxidation) process, which involves transformation of solid Co[TCNQ] 2 (H 2 O) 2 back to parent TCNQ crystals, also is controlled by nucleation-growth kinetics. The overall chemically reversible process that represents this transformation is described by the reaction: (s) . Ex situ SEM images illustrated that this reversible TCNQ/Co[TCNQ] 2 (H 2 O) 2 conversion process is accompanied by drastic size and morphology changes in the parent solid TCNQ. In addition, different sizes of needle-shaped nanorod/nanowire crystals of Co[TCNQ] 2 (H 2 O) 2 are formed depending on the method of surface immobilization.
Journal of The American Chemical Society, 2007
A generic method for the synthesis of metal-7,7,8,8-tetracyanoquinodimethane (TCNQ) chargetransfe... more A generic method for the synthesis of metal-7,7,8,8-tetracyanoquinodimethane (TCNQ) chargetransfer complexes on both conducting and nonconducting substrates is achieved by photoexcitation of TCNQ in acetonitrile in the presence of a sacrificial electron donor and the relevant metal cation. The photochemical reaction leads to reduction of TCNQ to the TCNQmonoanion. In the presence of M x+ (MeCN), reaction with TCNQ -(MeCN) leads to deposition of M x+ [TCNQ]x crystals onto a solid substrate with morphologies that are dependent on the metal cation. Thus, CuTCNQ phase I photocrystallizes as uniform microrods, KTCNQ as microrods with a random size distribution, AgTCNQ as very long nanowires up to 30 µm in length and with diameters of less than 180 nm, and Co[TCNQ]2(H2O)2 as nanorods and wires. The described charge-transfer complexes have been characterized by optical and scanning electron microscopy and IR and Raman spectroscopy. The CuTCNQ and AgTCNQ complexes are of particular interest for use in memory storage and switching devices. In principle, this simple technique can be employed to generate all classes of metal-TCNQ complexes and opens up the possibility to pattern them in a controlled manner on any type of substrate.
Journal of Physical Chemistry B, 2009
The preparation and characterization of a series of ionic liquids based on S-alkyl thiolonium, S-... more The preparation and characterization of a series of ionic liquids based on S-alkyl thiolonium, S-alkyl thiotetrazolium, or S-alkyl thiobenzolium cations coupled with bis(trifluoromethanesulfonyl)amide, trifluoromethanesulfonate, alkyl phosphate, chloride, and hexafluorophosphate anions are reported. All are liquid at room temperature, except the chloride salt, which has a melting point of 92 degrees C. The electrochemical characteristics of this class of ionic liquid have been determined by cyclic voltammetry. Potential windows of the ionic liquids have been obtained at glassy carbon, platinum, and gold electrodes and found to be the largest at glassy carbon, but are limited by oxidation of the thioether-functionalized cation. The voltammetry of IUPAC reference potential scale systems, ferrocene/ferrocenium, cobaltocenium/cobaltocene, and decamethylferrocene/decamethylferrocenium have been evaluated, with the last being most widely applicable. Nonadditivity of Faradaic current is found in the voltammograms of decamethylferrocene in the presence of ferrocene and cobaltocenium. Diffusion coefficient, viscosity, ionic conductivity, double layer capacitance, and other physical properties have also been measured. The dependence of the diffusion coefficient vs viscosity follows the Stokes-Einstein relationship. The properties of the ionic liquids are compared with the related imidazolium family of ionic liquids.
Journal of The American Chemical Society, 2009
Unexpected nonadditivity of currents encountered in the electrochemistry of mixtures of ferrocene... more Unexpected nonadditivity of currents encountered in the electrochemistry of mixtures of ferrocene (Fc) and cobaltocenium cation (Cc + ) as the PF 6salt has been investigated by direct current (dc) and Fourier-transformed alternating current (ac) cyclic voltammetry in two aprotic (1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate) and three protic (triethylammonium formate, bis(2-hydroxyethyl)ammonium acetate, and triethylammonium acetate) ionic liquids (ILs). The voltammetry of the individual Fc 0/+ and Cc +/0 couples always exhibits near-Nernstian behavior at glassy carbon and gold electrodes. As expected for an ideal process, the reversible formal potentials and diffusion coefficients at 23 ( 1°C in each IL determined from measurement on individual Fc and Cc + solutions were found to be independent of electrode material, concentration, and technique used for the measurement. However, when Fc and Cc + were simultaneously present, the dc and ac peak currents per unit concentration for the Fc 0/+ and Cc +/0 processes were found to be significantly enhanced in both aprotic and protic ILs. Thus, the apparent diffusion coefficient values calculated for Fc and Cc + were respectively found to be about 25 and 35% larger than those determined individually in the aprotic ILs. A similar change in the Fc 0/+ mass transport characteristics was observed upon addition of tetrabutylammonium hexafluorophosphate (Bu 4 NPF 6 ), and the double layer capacitance also varied in distinctly different ways when Fc and Cc + were present individually or in mixtures. Importantly, the nonadditivity of Faradaic current is not associated with a change in viscosity or from electron exchange as found when some solutes are added to ILs. The observation that the 1 H NMR T 1 relaxation times for the proton resonance in Cc + also are modified in mixed systems implies that specific interaction with aggregates of the constituent IL ionic species giving rise to subtle structural changes plays an important role in modifying the mass transport, double layer characteristics, and dynamics when solutes of interest in this study are added to ILs. Analogous voltammetric changes were not observed in studies in organic solvent media containing 0.1 M added supporting electrolyte. Implications of the nonadditivity of Faradaic and capacitance terms in ILs are considered.
Chemistry of Materials, 2007
Chemically synthesized AgTCNQ exists in two forms that differ in their morphologies (needles and ... more Chemically synthesized AgTCNQ exists in two forms that differ in their morphologies (needles and microcrystals) and colors (red and blue). It is now shown that both forms exhibit essentially indistinguishable X-ray diffraction, spectroscopic, and thermochemical data, implying that they are not separate phases, as implied in some literature. Electrochemical reduction of TCNQ (MeCN) in the presence of Ag + (MeCN) generates both red and blue AgTCNQ. On glassy carbon, platinum, or indium tin oxide electrodes and at relatively positive deposition potentials, slow growth of high aspect ratio, red needle AgTCNQ crystals occurs. After longer times and at more negative deposition potentials, blue microcrystalline AgTCNQ thin films are favored. Blue AgTCNQ is postulated to be generated via reduction of a Ag + [(TCNQ •-)(TCNQ)] (MeCN) intermediate. At even more negative potentials, Ag (metal) formation inhibits further growth of AgTCNQ. On a gold electrode, Ag (metal) deposition occurs at more positive potentials than on the other electrode materials examined. However, surface plasmon resonance data indicate that a small potential region is available between the stripping of Ag (metal) and the oxidation of TCNQ •-(MeCN) back to TCNQ (MeCN) where AgTCNQ may form. AgTCNQ in both the red and blue forms also can be prepared electrochemically on a TCNQ (s) modified electrode in 0.1 M AgNO 3(aq) where deposition of Ag (metal) onto the TCNQ (s) crystals allows a charge transfer process to occur. However, the morphology formed in this solid-solid phase transformation is more difficult to control.
International Journal of Gynecology & Obstetrics, 1987
In a community survey 521 women aged 35-59 were selected at random from all patients registered i... more In a community survey 521 women aged 35-59 were selected at random from all patients registered in two groups practices. They were interviewed at home and assessed by means of standardised psychiatric measures and detailed gynaecological inquiry. Levels of psychiatric morbidity were found to be within the expected range for such a sample. Both psychiatric morbidity and the personality dimension
Langmuir : the ACS journal of surfaces and colloids, Jan 8, 2015
Commonly, significant discrepancies are reported in theoretical and experimental comparisons of D... more Commonly, significant discrepancies are reported in theoretical and experimental comparisons of DC voltammograms derived from a monolayer or close to monolayer coverage of redox active surface-confined molecules. For example, broader than predicted voltammetric wave shapes are attributed to thermodynamic or kinetic dispersion derived from distributions in reversible potentials ($E^0$) and electrode kinetics ($k^0$), respectively. Recent availability of experimentally estimated distributions of E0E^0E0 and k0k^0k0 values derived from analysis of data for small numbers of surface-confined modified azurin metalloprotein molecules now allow more realistic modelling to be undertaken, assuming the same distributions apply under conditions of high surface coverage relevant to voltammetric experiments. In this work, modelling based on conventional and stochastic kinetic theory is considered, and the computationally far more efficient conventional model is shown to be equivalent to the stochasti...
Journal of experimental psychology. Animal learning and cognition, 2014
Visual search for complex natural targets requires focal attention, either cued by predictive sti... more Visual search for complex natural targets requires focal attention, either cued by predictive stimulus associations or primed by a representation of the most recently detected target. Because both processes can focus visual attention, cuing and priming were compared in an operant search task to evaluate their relative impacts on performance and to determine the nature of their interaction in combined treatments. Blue jays were trained to search for pairs of alternative targets among distractors. Informative or ambiguous color cues were provided before each trial, and targets were presented either in homogeneous blocked sequences or in constrained random order. Initial task acquisition was facilitated by priming in general, but was significantly retarded when targets were both cued and primed, indicating that the two processes interfered with each other during training. At asymptote, attentional effects were manifested mainly in inhibition, increasing latency in miscued trials and de...
International journal of sports medicine, 1998
The purpose of this study was to compare blood markers associated with eccentrically biased exerc... more The purpose of this study was to compare blood markers associated with eccentrically biased exercise and muscle damage, after two bouts of downhill running. Nine active, untrained males performed 2 x 45 min bouts of downhill running (-0.16 radians), at a speed that would elicit 70% of each subjects VO2max, on a level grade; runs were spaced 14d apart (RUN1, RUN2). Blood samples were obtained before, after, and every hour for 12 h after exercise, as well as every 24 h for 5 d, to assess numbers of circulating neutrophils, monocytes, and lymphocytes, serum cortisol, creatine kinase (CK); subjective sensations of delayed onset muscle soreness (DOMS) were monitored. To control for diurnal variation, two weeks prior to the RUN1, subjects had blood draws performed at the same time as would occur after exercise, but did no exercise (CONTROL). During the 5 d after exercise, DOMS and CK were significantly greater (p < 0.05) after RUN1 compared to RUN2 and CONTROL. During the 12 h after RU...
The electrochemical oxidation of cobalt(III) dithiocarbamates and diselenocarbamates (CoL 3 ) in ... more The electrochemical oxidation of cobalt(III) dithiocarbamates and diselenocarbamates (CoL 3 ) in acetonitrile + 0.1 M Bu 4 NPF 6 is shown to occur via the mechanism: (E) CoL 3 l[CoL 3 ] + + e − ; (C 2 ) 2[CoL 3 ] + [Co 2 L 5 ] + + oxidized ligand; (C) [Co 2 L 5 ] + + 2CH 3 CN CoL 3 +[CoL 2 (CH 3 CN) 2 ] + . A combination of electrochemical, electrospray mass spectrometry, and 59 Co/ 77 Se NMR experiments confirms that the binuclear species, [Co 2 L 5 ] + , reacts with acetonitrile forming CoL 3 and [CoL 2 (CH 3 CN) 2 ] + . At the electrode surface, CoL 3 species generated by this reaction may then be reoxidised resulting in an enhanced peak or limiting current. Consequently, the oxidation of CoL 3 in acetonitrile represents an overall EC 2 C mechanism. The data obtained from cyclic voltammetry at Pt disc electrodes and steady-state hydrodynamic voltammetry at platinum channel electrodes for oxidation of CoL 3 were modelled according to this EC 2 C scheme using the commercial DigiSim electrochemical simulation package and the backwards implicit finite difference technique, respectively. Good fits between experiment and simulation were obtained using the same kinetic parameters for both methods. The calculated dimerisation rate constant (C 2 step) is similar to the value obtained in dichloromethane, which is uncomplicated by reaction of [Co 2 L 5 ] + with the solvent. It was observed that if either voltammetric technique was used in isolation, a wider range of combinations of kinetic parameters could be utilised in order to obtain satisfactory fits between experiment and theory.