Cobalt Phthalocyanine Modified Electrodes Utilised in Electroanalysis: Nano-Structured Modified Electrodes vs. Bulk Modified Screen-Printed Electrodes

Cobalt phthalocyanine (CoPC) compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC) onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes L-ascorbic acid, oxygen and hydrazine. It is found that no “electrocatalysis” is observed towards L-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where “electrocatalysis” has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate

Pencil drawn paper based supercapacitors

© 2016 The Royal Society of Chemistry. This is the first comprehensive analysis of paper-based supercapacitors, P-SCs, that are produced utilising commercially available pencils to draw an interdigitated design upon common household printing paper, developing cheap, green and reliable low profile electrical conductors and electrodes. The P-SCs are optimised in terms of the composition of pencil used, the number of layers and the analysis of single or double sided interdigitated electrode designs; such a comprehensive study is seldom explored in previous literature. A full analysis of the physical and electrochemical properties of the pencil drawn electrodes has been performed, including the application of a new capacitive testing/evaluation circuit applied to charge/discharge measurements/analysis, which provides a revolutionary and unambiguous analysis of the capacitance of the fabricated electrodes; an easy to use experiment guide is presented. The P-SCs are benchmarked using 0.1 M H 2 SO 4 as the aqueous electrolyte. The P-SCs demonstrate a specific capacitance of ∼10.6 μF mg -1 at a charge current of 0.46 A g -1 . The P-SCs are integrated into a novel pouch design, providing a flexible, cheap and easily manufactured supercapacitor, which demonstrates a capacitance of ∼101.4 μF, exhibiting a specific capacitance of ∼42.4 μF g -1 at a current density of 0.46 A g -1 , exhibiting energy and power densities of ∼0.45 J mg -1 (0.125 mW h mg -1 ) and ∼0.03 W mg -1 respectively. The pouch cell, fabricated from P-SCs, utilises five parallel double-sided pencil drawn electrodes, with paper separators, and retains 82.2% of its maximum capacitance, after 5121 charge/discharge cycles at a current density of 0.09 A g -1 . Last, a solid state P-SC is developed utilising a PVA-H 2 SO 4 solid electrolyte, which demonstrates a specific capacitance of 141.8 μF g -1 , at a charging current of 4.33 μA g -1

Highly sensitive amperometric sensing of nitrite utilizing bulk-modified MnO2 decorated Graphene oxide nanocomposite screen-printed electrodes

© 2017 Elsevier Ltd A screen-printed amperometric sensor based on a carbon ink bulk-modified with MnO2 decorated graphene oxide (MnO2/GO-SPE) nanocomposite was investigated for its ability to serve as a sensor towards nitrite. The composite was prepared by simple ultrasonication and reflux methodology and was characterized by FT-IR spectroscopy, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, atomic force microscopy and electrochemically using cyclic voltammetry, chronoamperometry and differential pulse voltammetry techniques. The MnO2/GO-SPE was found to exhibit an electro-catalytic activity for the electrochemical oxidation of nitrite in 0.1 M phosphate buffer solution (pH 7.4). The electrochemical oxidation of nitrite occurs at +0.55 V (Vs. Ag/AgCl) with a limit of detection (3σ) found to be 0.09 μM and with two linear ranges of 0.1 μM to 1 μM and 1 μM to 1000 μM with sensitivities of 1.25 μAμM−1 cm−2 and 0.005 μAμM−1 cm−2 respectively. Furthermore, the MnO2/GO-SPE showed an excellent anti-interference ability towards a range of commonly encountered electroactive species and metal ions. Additionally, the fabricated MnO2/GO-SPE nitrite sensor presented an excellent selectivity, reproducibility and stability. The presented study widens the scope of applications of graphene-based nanocomposite materials for on-site monitoring of nitrite

Use of Screen-printed Electrodes Modified by Prussian Blue and Analogues in Sensing of Cysteine

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim The utilisation of screen-printing technology allows for a mass scalable approach for the production of electrochemical screen-printed electrodes (SPEs) and the presence of a redox mediator can add new possibilities to the electrochemical properties of the SPEs. Among the materials used as redox mediators, cyanidoferrates polymers can be used for electro-oxidation of cysteine. In this work, two monomers, namely, [Fe(CN) 6 ] 4− and [Fe(CN) 5 NH 3 ] 3− were used to produce Prussian blue (PB) and Prussian blue-Ammine (PB-Ammine), respectively. In addition, two modification methods were compared, firstly via a drop-casting and secondly by the incorporation of these materials into a printable ink. The SPE modified by PB-Ammine (drop-casting) exhibits the highest electroactive area, however the highest heterogeneous rate constant was found with the SPE modified by PB-Ammine that was incorporated into the ink. The highest value of the constant of electro-oxidation of cysteine and lowest limit of detection was also observed in the SPE modified by PB incorporated into the ink. These studies suggest that the electrocatalytic properties of SPE modified by PB and PB-Ammine are dependent upon the availability of Fe 3+ catalytic sites and the increased kinetics of the chemical reaction between the catalytic sites and the analyte

ORAI1 Ca2+ channel as a therapeutic target in pathological vascular remodelling

Cardiovascular disease (CVD) defines the conditions affecting the heart and blood vessels. CVD is currently the leading cause of global mortality, accounting for an estimated 17 million deaths annually (WHO, 2017). This figure is anticipated to rise as the prevalence in low and middle-income countries increases. CVD is associated with classical risk factors, including obesity (Poirier et al., 2006), smoking (Keto et al., 2016), family history (Dorairaj and Panniyammakal, 2012; Jeemon et al., 2017), and diabetes (Rydén et al., 2013; Shah et al., 2015). Atherosclerotic CVD (e.g., ischaemic heart disease, peripheral arterial disease, cerebrovascular disease, renovascular disease), pulmonary hypertension and aneurysm formation have all been associated with pathological remodelling behaviour of the native vascular smooth muscle cells (VSMC) within the arterial wall. Similarly, failure of surgical revascularisation to treat atherosclerotic CVD lesions (bypass grafting with autologous vein or prosthetic graft) or percutaneous coronary intervention/peripheral artery endovascular intervention (angioplasty+/−stenting) is associated with neointimal hyperplasia (NIH) which is also a manifestation of pathological vascular remodelling. The ability to selectively inhibit such pathological remodelling of VSMC is therefore considered to be a potentially fruitful therapeutic strategy across this range of cardiovascular pathologies. In order to achieve this, an identifiable, specific, druggable target is required. In this review we present an update on the evidence supporting the ORAI1 Ca2+ channel as a potential therapeutic target and the current status of inhibitor development. The focus is on atherosclerotic CVD and NIH as little evidence exists regarding aneurysm disease in this context and we recently reviewed the evidence supporting ORAI1 as a target in pulmonary hypertension (Rode et al., 2018)

Trace manganese detection via differential pulse cathodic stripping voltammetry using disposable electrodes: Additively manufactured nanographite electrochemical sensing platforms

Additive manufacturing is a promising technology for the rapid and economical fabrication of portable electroanalytical devices. In this paper we seek to determine how our bespoke additive manufacturing feedstocks act as the basis of an electrochemical sensing platform towards the sensing of manganese(ii) via differential pulse cathodic stripping voltammetry (DPCSV), despite the electrode comprising only 25 wt% nanographite and 75 wt% plastic (polylactic acid). The Additive Manufactured electrodes (AM-electrodes) are also critically compared to graphite screen-printed macroelectrodes (SPEs) and both are explored in model and real tap-water samples. Using optimized DPCSV conditions at pH 6.0, the analytical outputs using the AM-electrodes are as follows: limit of detection, 1.6 × 10-9 mol L-1 (0.09 μg L-1); analytical sensitivity, 3.4 μA V μmol-1 L; linear range, 9.1 × 10-9 mol L-1 to 2.7 × 10-6 mol L-1 (R2 = 0.998); and RSD 4.9% (N = 10 for 1 μmol L-1). These results are compared to screen-printed macroelectrodes (SPEs) giving comparable results providing confidence that AM-electrodes can provide the basis for useful electrochemical sensing platforms. The proposed electroanalytical method (both AM-electrodes and SPEs) is shown to be successfully applied for the determination of manganese(ii) in tap water samples and in the analysis of a certified material (drinking water). The proposed method is feasible to be applied for in-loco analyses due to the portability of sensing; in addition, the use of AM-printed electrodes is attractive due to their low cost

High yield synthesis of hydroxyapatite (HAP) and Palladium Doped HAP via a wet chemical synthetic route

© 2016 by the authors; licensee MDPI, Basel, Switzerland. A novel procedure for the synthesis of both hydroxyapatite (HAP) and palladium doped HAP via a wet chemical precipitation method is described herein. X-ray Diffraction (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) and Fourier Transform Infrared (FT-IR) Spectroscopy are utilised to characterise the synthesised material’s morphology, structure and crystallinity. The developed synthetic protocol produces high purity HAP with an average yield of 83.7 (±0.10)% and an average particle size of 58.2 (±0.98) nm, such synthesis has been achieved at room temperature and within a time period of less than 24 h. Additionally, in order to enhance the overall conductivity of the material, a range of Pd (2, 4 and 6 wt %) metal doped HAP has been synthesised, characterised and, for the first time, applied towards the competitive electrocatalytic detection of hydrazine, exhibiting a linear range of 50–400 μM with a limit of detection (3σ) of 30 µM

Review of parameterisation and a novel database (LiionDB) for continuum Li-ion battery models

The Doyle–Fuller–Newman (DFN) framework is the most popular physics-based continuum-level description of the chemical and dynamical internal processes within operating lithium-ion-battery cells. With sufficient flexibility to model a wide range of battery designs and chemistries, the framework provides an effective balance between detail, needed to capture key microscopic mechanisms, and simplicity, needed to solve the governing equations at a relatively modest computational expense. Nevertheless, implementation requires values of numerous model parameters, whose ranges of applicability, estimation, and validation pose challenges. This article provides a critical review of the methods to measure or infer parameters for use within the isothermal DFN framework, discusses their advantages or disadvantages, and clarifies limitations attached to their practical application. Accompanying this discussion we provide a searchable database, available at www.liiondb.com, which aggregates many parameters and state functions for the standard DFN model that have been reported in the literature

Large CP Violation in B_s Meson Mixing with EDM constraint in Supersymmetry

Motivated by the recent measurement of the like-sign dimuon charge asymmetry, we investigate anomalous CP violation in the B_s- bar{B}_s mixing within the supersymmetry. We show that when gluino diagrams dominate supersymmetry contributions, it is very difficult to realize a large B_s- bar{B}_s mixing phase under the constraint from electric dipole moments barring cancellations. This constraint can be ameliorated by supposing superparticles decoupled. In this limit, we find that it is possible to achieve the large CP asymmetry, and the branching ratio of B_s -> mu^+ mu^- tends to become sizable.Comment: 20 pages, 5 figure

Electro-Magnetic Nucleon Form Factors and their Spectral Functions in Soliton Models

It is demonstrated that in simple soliton models essential features of the electro-magnetic nucleon form factors observed over three orders of magnitude in momentum transfer $t$ are naturally reproduced. The analysis shows that three basic ingredients are required: an extended object, partial coupling to vector mesons, and relativistic recoil corrections. We use for the extended object the standard skyrmion, one vector meson propagator for both isospin channels, and the relativistic boost to the Breit frame. Continuation to timelike $t$ leads to quite stable results for the spectral functions in the regime from the 2- or 3-pion threshold to about two rho masses. Especially the onset of the continuous part of the spectral functions at threshold can be reliably determined and there are strong analogies to the results imposed on dispersion theoretic approaches by the unitarity constraint.Comment: 24 pages, (RevTeX), 5 PS-figures; Data points in fig.2 and corresponding references added. Final version, to be published in Z.Physik