Electrochemical synthesis of mesoporous CoPt nanowires for methanol oxidation

A new electrochemical method to synthesize mesoporous nanowires of alloys has been developed. Electrochemical deposition in ionic liquid-in-water (IL/W) microemulsion has been successful to grow mesoporous CoPt nanowires in the interior of polycarbonate membranes. The viscosity of the medium was high, but it did not avoid the entrance of the microemulsion in the interior of the membrane"s channels. The structure of the IL/W microemulsions, with droplets of ionic liquid (4 nm average diameter) dispersed in CoPt aqueous solution, defined the structure of the nanowires, with pores of a few nanometers, because CoPt alloy deposited only from the aqueous component of the microemulsion. The electrodeposition in IL/W microemulsion allows obtaining mesoporous structures in which the small pores must correspond to the size of the droplets of the electrolytic aqueous component of the microemulsion. The IL main phase is like a template for the confined electrodeposition. The comparison of the electrocatalytic behaviours towards methanol oxidation of mesoporous and compact CoPt nanowires of the same composition, demonstrated the porosity of the material. For the same material mass, the CoPt mesoporous nanowires present a surface area 16 times greater than compact ones, and comparable to that observed for commercial carbon-supported platinum nanoparticles.

Circulating microRNAs: The Future of Biomarkers in Anti-doping Field.

microRNAs (miRNAs) are small non-coding RNAs that regulate various biological processes. Cell-free miRNAs have been proposed as biomarkers of disease, including diagnosis, prognosis, and monitoring of treatment responses. These circulating miRNAs are highly stable in several body fluids, including plasma and serum; hence, in view of their potential use as novel, non-invasive biomarkers, the profiles of circulating miRNAs have been explored in the field of anti-doping. This chapter describes the enormous potential of circulating miRNAs as a new class of biomarkers for the detection of doping substances, and highlights the advantages of measuring these stable species over other methods that have already been implemented in anti-doping regimes. Incorporating longitudinal measurements of circulating miRNAs into the Athlete Biological Passport is proposed as an efficient strategy for the implementation of these new biomarkers. Furthermore, potential challenges related to the transition of measurements of circulating miRNAs from research settings to practical anti-doping applications are presented.

Analytical Strategies for Doping Control Purposes: Needs, Challenges, and Perspectives.

The fight against doping in sports has been governed since 1999 by the World Anti-Doping Agency (WADA), an independent institution behind the implementation of the World Anti-Doping Code (Code). The intent of the Code is to protect clean athletes through the harmonization of anti-doping programs at the international level with special attention to detection, deterrence and prevention of doping.1 A new version of the Code came into force on January 1st 2015, introducing, among other improvements, longer periods of sanctioning for athletes (up to four years) and measures to strengthen the role of anti-doping investigations and intelligence. To ensure optimal harmonization, five International Standards covering different technical aspects of the Code are also currently in force: the List of Prohibited Substances and Methods (List), Testing and Investigations, Laboratories, Therapeutic Use Exemptions (TUE) and Protection of Privacy and Personal Information. Adherence to these standards is mandatory for all anti-doping stakeholders to be compliant with the Code. Among these documents, the eighth version of International Standard for Laboratories (ISL), which also came into effect on January 1st 2015, includes regulations for WADA and ISO/IEC 17025 accreditations and their application for urine and blood sample analysis by anti-doping laboratories.2 Specific requirements are also described in several Technical Documents or Guidelines in which various topics are highlighted such as the identification criteria for gas chromatography (GC) and liquid chromatography (LC) coupled to mass spectrometry (MS) techniques (IDCR), measurements and reporting of endogenous androgenic anabolic agents (EAAS) and analytical requirements for the Athlete Biological Passport (ABP).

Sosiaalisten ongelmien retoriikkaa : tapaus doping

Summary: Rhetoric in discussing social problems: The case of doping

Fast and sensitive supercritical fluid chromatography - tandem mass spectrometry multi-class screening method for the determination of doping agents in urine.

This study shows the possibility offered by modern ultra-high performance supercritical fluid chromatography combined with tandem mass spectrometry in doping control analysis. A high throughput screening method was developed for 100 substances belonging to the challenging classes of anabolic agents, hormones and metabolic modulators, synthetic cannabinoids and glucocorticoids, which should be detected at low concentrations in urine. To selectively extract these doping agents from urine, a supported liquid extraction procedure was implemented in a 48-well plate format. At the tested concentration levels ranging from 0.5 to 5 ng/mL, the recoveries were better than 70% for 48-68% of the compounds and higher than 50% for 83-87% of the tested substances. Due to the numerous interferences related to isomers of steroids and ions produced by the loss of water in the electrospray source, the choice of SFC separation conditions was very challenging. After careful optimization, a Diol stationary phase was employed. The total analysis time for the screening assay was only 8 min, and interferences as well as susceptibility to matrix effect (ME) were minimized. With the developed method, about 70% of the compounds had relative ME within the range ±20%, at a concentration of 1 and 5 ng/mL. Finally, limits of detection achieved with the above-described strategy including 5-fold preconcentration were below 0.1 ng/mL for the majority of the tested compounds. Therefore, LODs were systematically better than the minimum required performance levels established by the World anti-doping agency, except for very few metabolites.

Electrochemical Characterisation of Filter Media Properties and Their Exploitation in Enhanced Filtration

Streaming potential measurements for the surface charge characterisation of different filter media types and materials were used. The equipment was developed further so that measurements could be taken along the surfaces, and so that tubular membranes could also be measured. The streaming potential proved to be a very useful tool in the charge analysis of both clean and fouled filter media. Adsorption and fouling could be studied, as could flux, as functions of time. A module to determine the membrane potential was also constructed. The results collected from the experiments conducted with these devices were used in the study of the theory of streaming potential as an electrokinetic phenomenon. Several correction factors, which are derived to take into account the surface conductance and the electrokinetic flow in very narrow capillaries, were tested in practice. The surface materials were studied using FTIR and the results compared with those from the streaming potentials. FTIR analysis was also found to be a useful tool in the characterisation of filters, as well as in the fouling studies. Upon examination of the recorded spectra from different depths in a sample it was possible to determine the adsorption sites. The influence of an external electric field on the cross flow microflltration of a binary protein system was investigated using a membrane electroflltration apparatus. The results showed that a significant improvement could be achieved in membrane filtration by using the measured electrochemical properties to help adjust the process conditions.

Electrochemistry and green chemical processes: electrochemical ozone production

After an introductory discussion emphasising the importance of electrochemistry for the so-called Green Chemical Processes, the article presents a short discussion of the classical ozone generation technologies. Next a revision of the electrochemical ozone production technology focusing on such aspects as: fundamentals, latest advances, advantages and limitations of this technology is presented. Recent results about fundamentals of electrochemical ozone production obtained in our laboratory, using different electrode materials (e.g. boron doped diamond electrodes, lead dioxide and DSAÒ-based electrodes) also are presented. Different chemical processes of interest to the solution of environmental problems involving ozone are discussed.

Electrochemical behavior of parent and photodegradation products of some selected pesticides

Electrochemical behavior of pesticides is extensively studied, but little attention has been given to the study of their degradation products (by-products) by electrochemical methods. However, the degradation products of pesticides can be even more toxic then the parent products and such studies should be encouraged. Therefore, the objective of this work was to evaluate the electroactivity of by-products of imazaquin, methylparathion, bentazon and atrazine, generated by UV irradiation and measured using cyclic and differential pulse voltammetry and UV-visible absorption spectrophotometry. Results have shown that several by-products exhibit electroactivity, allowing, in some cases, the simultaneous determination of both parent and degradation products.

Optimization of the use of carbon paste electrodes (CPE) for electrochemical study of the chalcopyrite

The use of carbon paste electrodes (CPE) of mineral sulfides can be useful for electrochemical studies to overcome problems by using massive ones. Using CPE-chalcopyrite some variables were electrochemically evaluated. These variables were: (i) the atmosphere of preparation (air or argon) of CPE and elapsed time till its use; (ii) scan rate for voltammetric measurements and (iii) chalcopyrite concentration in the CPE. Based on cyclic voltammetry, open-circuit potential and electrochemical impedance results the recommendations are: oxygen-free atmosphere to prepare and kept the CPE until around two ours, scan rates from 10 to 40 mV s-1, and chalcopyrite concentrations > 20%.

Electrochemical and theoretical evaluation of the interaction between dna and amodiaquine: evidence of the guanine adduct formation

The electrochemical behavior of the interaction of amodiaquine with DNA on a carbon paste electrode was studied using voltametric techniques. In an acid medium, an electroactive adduct is formed when amodiaquine interacts with DNA. The anodic peak is dependent on pH, scan rate and the concentration of the pharmaceutical. Adduct formation is irreversible in nature, and preferentially occurs by interaction of the amodiaquine with the guanine group. Theoretical calculations for optimization of geometry, and DFT analyses and on the electrostatic potential map (EPM), were used in the investigation of adduct formation between amodiaquine and DNA.

Electrochemical study, on mercury, of a Meta-nitroarylamine derivative of nor-β-lapachone, an antitumor and trypanocidal compound

The electrochemistry of 2,2-dimethyl-(3H)-3-(N-3'-nitrophenylamino)naphtho[1,2- b]furan-4,5-dione ([Q]-PhNO2), on mercury was investigated. The first peak is consistent with a quasi-reversible one-electron reduction of the ortho-quinone, forming [Q•-]-PhNO2, while the second one, bielectronic, corresponds to the simultaneous reduction of the latter radical to a dianion and the nitro group to a nitro radical anion. The second order rate constant, k disp, for the decay of [Q•-]-PhNO2 is 15.188 x 10³ ± 827 mol"1 L s"1 and the t1/2 equals 0.06 s. E¹7Ic values for [Q]-PhNO2 and its precursor, nor-β-lapachone, are similar. The ease of semiquinone generation and its stability are parameters statistically relevant in the correlation biochemical/theoretical aspects.

Structural and reactivity analyses of 2-benzylamino-1,4-naphthoquinone by X-ray characterization, electrochemical measurements, and dft single-molecule calculations

This study represents an integrated approach towards understanding the electronic and structural aspects of 2-benzylamino-1,4-naphthalenedione, a representative 2-amino-napfthoquinone. To this end, theoretical calculations performed at the B3PW91/6-31+G(d) level of density functional theory, electrochemical and X-ray structural investigation were employed. Two intramolecular H-bonds and other two intermolecular H-bonds were observed, including non-classical interactions. Cyclic voltammogram (CV) and differential pulse voltammetry (DPV) show two pairs of peaks, being each one a monoelectronic process.

A comparison of electrodeposited Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes in the electrochemical degradation of the direct yellow 86 dye

The electrochemical performance of electrodeposited Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes was galvanostatically evaluated (batch mode, 50 mA cm-2) to degrade the Direct Yellow 86 dye (100 or 200 mg L-1 in 0.1 mol L-1 Na2SO4 + 1.5 g L-1 NaCl), investigating the effect of pH and temperature. Similar results were obtained for both electrodes and the best conditions for removal of color and chemical oxygen demand are pH 7 and 40 °C, when 90% decolorization is attained by passing a charge of only ~0.13 A h L-1 and total mineralization is achieved with expenditure of ~5 kW h m-3.

Electrochemical study about zinc electrodeposition onto GCE and HOPG substrates

We carried out an electrochemical study about zinc electrodeposition onto GCE and HOPG substrates from an electrolytic plating bath containing 0.01M ZnSO4 + 1M (NH4)2SO4 at pH 7. Under our experimental conditions the predominant chemical species was the complex [ZnSO4(H2O)5]. The chronoamperometric study showed that zinc electrodeposition follows a typical 3D nucleation mechanism in both substrates. The average dG calculated for the stable nucleus formation was 6.92 x 10-21 J nuclei"1 and 1.35 x 10-20 J nuclei"1 for GCE and HOPG, respectively. The scanning electron microscopy (SEM) images showed different nucleation and growth processes on GCE and HOPG substrates at same overpotential.

Preparation of glasses and glass ceramics of heavy metal oxides containing silver: optical, structural and electrochemical properties

Silver containing heavy metal oxide glasses and glass ceramics of the system WO3-SbPO4-PbO-AgCl with different AgCl contents have been prepared and their thermal, structural and optical properties characterized. Glass ceramics containing metallic silver nanoparticles have been prepared by annealing glass samples at temperatures above the glass transition and analyzed by transmission electron microscopy and energy dispersive X-ray microanalysis. The presence of the metallic clusters has been also confirmed by the observation of a surface plasmon resonance band in the visible range. Cyclic voltammetric measurements indicated the presence of metallic silver into the glasses, even before to perform the thermal treatment.