Electrochemistry

We execute augmented Brownian dynamics (BD) simulation studies to show that the migration of flexible polyelectrolyte chains through nanochannels may be strongly governed by a complicated interplay between the electroviscous effects, near-wall interaction mechanisms, and diffusophoretic transport due to thermal gradients prevailing in the system. We further illustrate that in presence of mutually opposing pressure-driven and electro-osmotic transport and with an optimal choice of the ratio of the strength of these two flow fields, the electroviscous effects may turn out to be immensely consequential in strengthening the effective confinement of the polyelectrolyte. This, in turn may permit in achieving important biophysical feats that are otherwise obtainable only through significantly reduced nanochannel dimensions.

The influence of the halogen atom on the intrinsic properties of poly(3-halidethiophene)s has been investigated using experimental and theoretical methodologies. Specifically, the electrochemical, electrical, electronic and morphological properties of poly(3-bromothiophene) have been determined and compared with those recently reported for poly(3-chlorothiophene) [Aradilla et al., Polym. Chem., 2012, 3, 436.]. The electrochemical stability and porosity are smaller for poly(3-bromothiophene) than for poly(3-chlorothiophene) while the p-p* lowest transition energy is higher for the former than for the latter. Moreover, quantum mechanical calculations on model oligomers have evidenced that the conformational properties of poly(3-halidethiophene)s, where the halogen is fluorine, chloride or bromine, are dominated by steric interactions and, therefore, are significantly influenced by the size of the halogen atoms. Both the ionization potential and the p-p* lowest transition energy have been predicted to increase slightly when the p-donor character of the halogen atom decreases, in agreement with experimental observations. Scheme 1

The physiology of glomerular permselectivity remains mechanistically obscure, despite its importance in human disease. Although electrical contributions to glomerular permselectivity have long been considered important, two recent reports demonstrated enhanced glomerular permeability to anionic versus neutral polysaccharides. The interpretation of these observations is complicated by confounding of the effects of chemical modification on charge with effects on size and shape. In this report, neutral and anionic Ficoll are characterized by size-exclusion chromatography with online light scattering and viscometry and filtration through a highly defined anionic filtration membrane. Neutral and carboxymethylated Ficoll are nearly identical in size and conformation, yet carboxymethylated Ficoll is retained by an anionic membrane in excess of neutral Ficoll. This suggests that comparisons between clearances of neutral and carboxymethylated Ficoll may be a sensitive probe of electrostatic ...

Sickle cell haemoglobin differs from normal haemoglobin by a single amino aeid in its (} chain. This amino acid replacement, from glutamic aeid to valine, causes polymerisation of proteins into defined long insoluble fibres with a typical diameter of 21.5 nm. The polymerisation is triggered by the formation of d eo \\h aem o g lo b in from oxyhaemoglobin in low oxygen partial pressures, which results in a conformational change in the secondary structure o f the protein. Pathogenesis in sickle cell disease depends on the polymerisation and gelation of deoxygenated HbS molecules. In this work, an electrochemical method has been described to modulate the oxygen concentration in an optically transparent thin layer cell to produce deoxyhaemoglobin whilst monitoring the extent o f polymerisation using turbidity measurements. The oxygen was depleted in the vicinity o f the electrode and triggered the polymerisation. The dependence o f protein concentration, temperature. pH and ionic strength on the nucleation and elongation o f HbS polymerisation was characterised at the electrode surface and the kinetics of polymerisation was investigated using a model for fibrillogenesis describing a twostep process of nucleation followed by elongation. The rate constants, determined for a number of conditions, showed that nucleation is far slower than the growth whilst polymerisation at the surface was demonstrated to occur in three stages, with an initial time delay when no structures were observed followed b\ growth of fibrous hair-like strands and finally gel-like aggregation. An understanding of the factors which affect polymerisation at a surface and an insight into the dynamics and mechanism o f polymer aggregation and the pathophysiology o f sickle cell disease has been provided. A screening method for substances that effect the fibre nucleation and/or growth that could be valuable to the pharmaceutical industry for treating sickle cell disease is also presented. Chapter 1: Introduction 1.1 Sickle Cell Anaemia Sickle cell anaemia (SCA) is the most common type o f a group o f autosomal recessive disorders termed as sickle cell disease (SCD). It is a genetic disorder o f the blood in which the red blood cells (RBC) curve into a sickle shape due to the production and, most importantly, polymerisation o f mutant sickle haemoglobin (HbS). It is a disease which afflicts millions o f people throughout the world, in particular those whose ancestors come from equatorial regions such as sub-Saharan Africa, Saudi Arabia, South America and India, and clinical manifestations include amongst others severe haemolytic anaemia, pain crises, stroke, and chronic damage to vital organs such as lungs, kidneys and liver. The fundamental process o f HbS polymerisation inside sickle erythrocytes has been studied by almost every physical technique o f protein chemistry, including electron microscopy, single-crystal X-ray diffraction, nuclear magnetic resonance, circular dichroism spectroscopy, laser photolysis and temperature jum p kinetics. A large part of the success in understanding this process can be attributed to the application of these many different techniques. However, even though the polymerisation o f HbS has probably become the best understood o f all protein selfassembly systems, SCA is still a major global health problem, with an estimated 120,000 to 250,000 affected infants born annually [1], and at present most clinical interventions can be classified as tertiary prevention, such as therapies to ameliorate anaemia, reduction o f the frequency o f pain crises, or prevention o f stroke recurrences. As o f yet, there are no preventative treatments. In this chapter, recent advances into the study o f HbS polymerisation, it's structural and physical properties as well as the critical conditions required for polymer formation, are described. Electrochemistry is also introduced and a summary o f relevant visualisation techniques is reported.

All chemical reactions involve electron rearrangement within or between molecules. The changes are best studied by methods such as electrochemistry, but these have been developed mainly for liquids and solids rather than gases. This exclusion limits our understanding of electron transfer processes that are central in plasma systems, which are of high scientific, industrial, and environmental importance. Here we describe electrochemical measurements in the gas phase of small organic molecules contained in flame plasma, by probing the redox activity of the resulting chemical fragments using cyclic voltammetry. Unique current-voltage spectra are recorded for eight amino acids and their fragments, through specific electron transfer reactions at the solid/gas interface. We identify and assign Faradaic peaks in the current-voltage spectra to the fragments using stable analogues of the fragments and in situ mass spectroscopy. We show that this approach provides unambiguous identification o...

Graphene nanoflakes (GNF) with lateral dimensions of ca. 30 nm and edge-terminated with carboxylic acid functionalities have been characterised and the influence of acidic functionalities on the [Fe(CN) 6 ] 3À/4À redox couple studied using cyclic voltammetry and spectroelectrochemical methods. The presence of the COOH-terminated GNF in solution as well as immobilised onto an electrode surface was found to inhibit the redox reaction, supporting the conclusion that GNF promote instability of [Fe(CN) 6 ] 3À/4À in solution. The redox reaction was also much less influenced by the presence of GNF in D 2 O, highlighting the role played by readily available protons in destabilising the [Fe(CN) 6 ] 3À/4À redox couple. In the presence of GNF in solution, an additional, very intense cyanide stretch IR band was observed that was attributed to the formation of a new, non-soluble species. When D 2 O was used as the solvent, the IR spectrum showed no evidence of a new cyano species.

Sickle cell haemoglobin differs from normal haemoglobin by a single amino aeid in its (} chain. This amino acid replacement, from glutamic aeid to valine, causes polymerisation of proteins into defined long insoluble fibres with a typical diameter of 21.5 nm. The polymerisation is triggered by the formation of d eo \\h aem o g lo b in from oxyhaemoglobin in low oxygen partial pressures, which results in a conformational change in the secondary structure o f the protein. Pathogenesis in sickle cell disease depends on the polymerisation and gelation of deoxygenated HbS molecules. In this work, an electrochemical method has been described to modulate the oxygen concentration in an optically transparent thin layer cell to produce deoxyhaemoglobin whilst monitoring the extent o f polymerisation using turbidity measurements. The oxygen was depleted in the vicinity o f the electrode and triggered the polymerisation. The dependence o f protein concentration, temperature. pH and ionic strength on the nucleation and elongation o f HbS polymerisation was characterised at the electrode surface and the kinetics of polymerisation was investigated using a model for fibrillogenesis describing a twostep process of nucleation followed by elongation. The rate constants, determined for a number of conditions, showed that nucleation is far slower than the growth whilst polymerisation at the surface was demonstrated to occur in three stages, with an initial time delay when no structures were observed followed b\ growth of fibrous hair-like strands and finally gel-like aggregation. An understanding of the factors which affect polymerisation at a surface and an insight into the dynamics and mechanism o f polymer aggregation and the pathophysiology o f sickle cell disease has been provided. A screening method for substances that effect the fibre nucleation and/or growth that could be valuable to the pharmaceutical industry for treating sickle cell disease is also presented. Chapter 1: Introduction 1.1 Sickle Cell Anaemia Sickle cell anaemia (SCA) is the most common type o f a group o f autosomal recessive disorders termed as sickle cell disease (SCD). It is a genetic disorder o f the blood in which the red blood cells (RBC) curve into a sickle shape due to the production and, most importantly, polymerisation o f mutant sickle haemoglobin (HbS). It is a disease which afflicts millions o f people throughout the world, in particular those whose ancestors come from equatorial regions such as sub-Saharan Africa, Saudi Arabia, South America and India, and clinical manifestations include amongst others severe haemolytic anaemia, pain crises, stroke, and chronic damage to vital organs such as lungs, kidneys and liver. The fundamental process o f HbS polymerisation inside sickle erythrocytes has been studied by almost every physical technique o f protein chemistry, including electron microscopy, single-crystal X-ray diffraction, nuclear magnetic resonance, circular dichroism spectroscopy, laser photolysis and temperature jum p kinetics. A large part of the success in understanding this process can be attributed to the application of these many different techniques. However, even though the polymerisation o f HbS has probably become the best understood o f all protein selfassembly systems, SCA is still a major global health problem, with an estimated 120,000 to 250,000 affected infants born annually [1], and at present most clinical interventions can be classified as tertiary prevention, such as therapies to ameliorate anaemia, reduction o f the frequency o f pain crises, or prevention o f stroke recurrences. As o f yet, there are no preventative treatments. In this chapter, recent advances into the study o f HbS polymerisation, it's structural and physical properties as well as the critical conditions required for polymer formation, are described. Electrochemistry is also introduced and a summary o f relevant visualisation techniques is reported.

Cr-Al2O3 Nano composite coatings with various contents of Al2O3 nanoparticles were prepared by electrodeposition inoptimized Cr plating bath containing different concentrations of Al2O3 nanoparticles. Direct current electrocodeposition technique wasused to deposit chromium layers with and without Al2O3 nanoparticles on mild carbon steel. The effects of current density, stirring rateand concentration of nanoparticles in the plating bath were investigated. Energy dispersive analysis technique was used to verify the presence of Al2O3 nanoparticles in the coated layers. Thecorrosion behaviors of coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopymethods in 0.05 mol/L HCl, 1 mol/L NaOH and 3.5% NaCl (mass fraction), respectively. Microhardness measurements and pin-on-disctribometer technique were used to investigate the wear behavior of the coatings.

Keying of lithium chloride alkali halide salt into the interlamellar space of nacrite clay mineral leads to a stable hybrid material that after calcination under inert atmosphere at 723 -873 K induces an amorphous metahybrid. The electrochemical impedance spectroscopy (EIS) was performed to investigate the electric/dielectric properties of the hybrid with various parameters: frequency and temperature. Equivalent circuit was proposed to fit the EIS data. The experiment results show that the ionic conduction mechanism is related to the motion of Li + cations which are thermally activated, named the hopping model. Furthermore, the resulting metahybrid obtained from dehydroxylation of the formal hybrid shows a superionic behavior with high ionic conductivity up to 10 -2 S•m -1 , good electrochemical stability and can be used as a solid electrolyte material for Li-ion batteries.

This study examined the formation mechanism of Li4Ti5O12 by a ball mill assisted solid-state reaction between Li2CO3 and TiO2 for applications in lithium ion batteries, also eects of TiO2 source such as rutile type and anatase type on the electrochemical performance of Li4Ti5O12. However, it is believed that the particle properties may depend signicantly on the synthesis process and starting materials, which lead to nal products with a range of sizes, morphologies, and even phases.

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A novel and rapid voltammetric assay for the simultaneous determination of monolinuron (MLN) and linuron (LIN) using an electrochemically pretreated pencil graphite electrode (PGE*) is reported for the first time. Enhanced oxidation peak currents of MLN and LIN were observed at PGE* when compared with electrochemically non-pretreated PGE. Differential pulse voltammetric (DPV) results showed distinct anodic peaks at 1.064 V and 1.170 V for MLN and LIN, respectively. Under optimum conditions, the detection limits were 3.7 × 10 -7 mol L -1 and 5.8 × 10 -7 mol L -1 for MLN and LIN respectively. The DPV method was applied for the quantitative determination of the mentioned compounds in spiked tap water samples enriched by solid phase extraction. The voltammetric results were in good agreement with high-performance liquid chromatography data.

A differential pulse voltammetric method for the determination of kojic acid (KA) was developed. The electrochemical behavior of KA at a multi-walled carbon nanotubes modified screen-printed electrode (MWCNTs-SPCE) was explored. A single irreversible oxidation peak was observed at a potential of 0.791 V and 0.989 V on the MWCNTs-SPCE and screen-printed carbon electrode (SPCE), respectively. Under the optimized conditions, the anodic peak current of KA recorded by differential pulse voltammetry varies linearly with KA concentration in the range 0.02-5 mM with a detection limit of 0.016 mM. The MWCNTs-SPCE was used for quantitative analysis of KA in food samples and the results indicate the feasibility of the amperometric method for KA analysis in routine detection.

A simply and high selectively electrochemical method for simultaneous determination of hydroquinone (HQ) and catechol (CC) has been developed at an electrochemically activated screen-printed carbon electrode (SPCE) modified with Prussian Blue (PB). The PB acted as a mediator and thereby enhanced the rate of electron transfer in chemical reaction. Various optimization studies such as the pH of the measuring solution, linear range of response, sensitivity and detection limit, were conducted to obtain maximum amperometric responses for analytes measurement. Differential pulse voltammetry (DPV) was used for the simultaneous determination of HQ and CC in their mixture, and the peak-to-peak separation for HQ and CC was about 0.11 V. The two corresponding well-defined oxidation peaks of HQ and CC at activated Prussian Blue-modified screen-printed carbon electrode (PB-SPCE) occur at -0.012 V and +0.094 V, respectively. Under the optimized condition in DPV, the oxidation peak current of HQ and of CC is linear over a range from 4.0 × 10 -6 M to 9.0 × 10 -5 M HQ and from 1.0 × 10 -6 M to 9.0 × 10 -5 M CC. The obtained detection limit for HQ and CC was 1.17 × 10 -7 M and 4.28 × 10 -7 M, respectively. DPV can be used for individual or simultaneous determination of HQ and CC. The proposed activated PB-SPCE was successfully applied to the simultaneous determination of HQ and CC in spiked tap water. Using the standard addition method, the average recovery of the proposed method based on activated PB-SPCE was 99.03% and 95.87% for HQ and CC, respectively.

The application of a multiple-scan strategy to nanosamples taken from 18 cross-sections of Bronze Age arms and armour, as well as two Roman coins using two solid-state electrochemical techniques, the voltammetry of immobilized microparticles (VIMP) and open circuit potential measurements (OCP) is described. The voltammetric responses in contact with aqueous acetate buffer can be attributed to the reduction of cuprite with variable degree of compaction and crystallinity revealing significant differences in the gradient of such properties with depth. Such differences are also revealed by "dry" OCP measurements connecting points in the cross section near and saeparated from the corrosion layer. The voltammetric study of the metallographic samples of the bronze objects shows correlation with the age of the objects, respectively the period of their deposition. We discuss also (potential) influence of different factors on the VIMP and OCP measurements, such as deposition context (soil, water), chemical composition of the copper alloys, and microstructural features (as-cast, annealed, work-hardened), and how to overcome these issues.

Research was carried out to experimentally evaluate the antioxidant capacity of several red and white wines using a superoxide dismutase (SOD) biosensor recently developed by the present authors. Measurements were performed by comparing the biosensor response to increasing concentration of the superoxide radical produced in solution by the xanthine/xanthine oxidase system, both in the presence and absence of the test sample. The results were compared with those of two traditional spectrophotometric methods and of a spectrofluorimetric method described in literature. Lastly, also the polyphenol, sulfite and ascorbic acid contents of the different wine samples examined were measured using a tyrosinase biosensor, a sulfite oxidase biosensor and an ascorbate oxidase biosensor, respectively.

OBJECTIVE—Large-for-gestational-age (LGA) infants (birth weight ≥90th centile) are a continuing problem in pregnancies of women with type 1 diabetes. We used the continuous glucose monitoring system (CGMS) to assess the relationship between 24-h diurnal glucose profiles in all three trimesters of pregnancy and infant birth weight. RESEARCH DESIGN AND METHODS—Twenty-nine pregnant women with type 1 diabetes used the CGMS during each trimester of pregnancy. The glucose profiles of the women with a normal-weight infant or an LGA infant were compared. RESULTS—Of the women with type 1 diabetes, 48% gave birth to an LGA infant. Fifty percent of these infants were already large for dates on ultrasound at <30 weeks of gestation (early LGA), and all these infants had a birth weight ≥97.7th centile. The diurnal glucose profiles show that the mothers of early LGA infants had elevated glucose levels for most of the day during the second trimester (P < 0.05). The median 24-h glucose level w...

Electrochemical approaches have played crucial roles in bio sensing because of their Potential in achieving sensitive, specific and low-cost detection of biomolecules and other bio evidences. Engineering the electrochemical sensing interface with nanomaterials tends to new generations of label-free biosensors with improved performances in terms of sensitive area and response signals. Here we applied Silicon Nanowire (SiNW) array electrodes (in an integrated architecture of working, counter and reference electrodes) grown by low pressure chemical vapor deposition (LPCVD) system with VLS procedure to electrochemically diagnose the presence of breast cancer cells as well as their response to anticancer drugs. Mebendazole (MBZ), has been used as antitubulin drug. It perturbs the anodic/cathodic response of the cell covered biosensor by releasing Cytochrome C in cytoplasm. Reduction of cytochrome C would change the ionic state of the cells monitored by SiNW biosensor. By applying well di...

An experimental system is described for validating electrochemical oxygen sensors implanted in tissues. The system is a modified hamster window chamber in which a thin layer of vascularized tissue is held between two plates, one plate having an observation window and the other plate having an array of oxygen sensors. This arrangement permits simultaneous recording of oxygen sensor signals and nondestructive visualization of the tissue adjacent to the sensors over periods of 1 mo or more, without the inhibitory effects of anesthesia. The system provides a means for study of the effects of spatial and temporal oxygen distributions on the sensor signals and adaptation of the tissue structure over time. Examples are given of sensor recordings and images of tissues with implanted oxygen sensor arrays.

By analyzing vesicle fl uids and crusted scabs from 136 persons with suspected monkeypox, we identifi ed 51 cases of monkeypox by PCR, sequenced the hemagglutinin gene, and confi rmed 94 % of cases by virus culture. PCR demonstrated chickenpox in 61 patients. Coinfection with both viruses was found in 1 additional patient. Monkeypox (MPX) virus is an orthopoxvirus that causes human MPX, a smallpoxlike disease reported in the African rainforests. Humans acquire the virus through direct contact with infected animals or patients (1). To determine whether MPX virus could potentially occupy the niche vacated by smallpox virus, the World Health Organization (WHO) conducted an active surveillance program during 1981–1986 in the Democratic Republic of Congo (DRC) and identified 338 MPX cases (67 % confirmed by virus culture). Epidemiologic data led to the conclusion that MPX was a sporadic disease with a low potential for person-to-person transmission and that infection could not sustain it...

Selective determination of caffeic acid, was carried out by using Screen Printed Carbon Electrode (SPCE) to give a reliable, scalable, and inexpensive electrochemical method with enhanced analytical performance. SPCE was first activated by linear sweep voltammetry using KOH solution, followed by its electrochemical grafting with cyclodextrins. Britton Robinson buffer (BRB) solution having pH 8.1, demonstrated a clear electrocatalytic impact towards caffeic acid oxidation, which indicated a greater current response compared to the activated electrode in the cyclic voltammetric and square wave voltammetric (SWV) investigations. The SWV waves at the activated SPCE was used under ideal conditions to produce a linear calibration curve with detection limits of (LoD, 4 sb/m) and quantification limits of (LoQ, 11 sb/m) of 0.38 mM and 1.1 M, respectively.

Fossil fuels, currently the leading source of energy, subsidize a lot of CO 2 to the environment, causing many environmental issues including the greenhouse effect. To address these challenges, there is a need to develop alternative and renewable energy resources for a sustainable future. Water, being a renewable source, is a promising candidate because of its ability to produce H 2 (HER-cathodic reaction) and O 2 (OERanodic reaction) by providing electricity. However, the overall efficiency of water splitting is limited due to the high overpotential for half-cell anodic reaction, thus becoming a hot area of research to beat its sluggish thermodynamics and slow kinetics. Molecular nanoclusters (MNCs) are emerging materials because of their unique optical, catalytic, magnetic, and electronic properties. These unique properties are due to various factors including electronic shell closing (Jellium model), geometric shell closing, high surface-to-volume ratio, and super atomic behavior, unlike their bulk counterparts. This chapter will summarize the well-developed research information on MNCs and their potential for OER. It will create a link between the reported and ongoing work, consequently helping the researchers to identify future research directions in nanocatalysis for making the water-splitting process an economically viable process for H 2 production.

The electrochemical reduction of solid C 60 abrasively attached in the form of microcrystals to graphite and glassy carbon electrode surfaces and then immersed in acetonitrile containing 0.1 M NBu 4 PF 6 or NBu 4 ClO 4 as the electrolyte has been studied. Voltammetric responses observed after the initial stages of redox cycling experiments, when redistribution processes occur, are consistent with those observed previously for so-called "film" deposits. The characteristic "steady-state" shape of the solid-state voltammetric response with a large potential gap between reduction and reoxidation responses is shown by chronoamperometric experiments to be associated with the presence of a nucleation and growth-type mechanism. The initial three reduction processes of C 60 attached to the electrode surface, which lead to the chemically reversible formation of only slightly soluble C 60 -and C 60 2-and finally to the loss of the soluble C 60 3-have been followed by ex situ SEM and in situ AFM experiments. The extent of the electrochemical conversion is shown to depend strongly on the crystal size, with larger crystals being affected only at the solid-liquid interfacial region. Evidence for stochastic processes further supports the proposed nucleation and growth-type mechanism. Crystal redistribution processes also are identified by the AFM measurements.

The formation of passive films on copper, 85/1S and 67/33 brasses has been investigated by potentiostatic and potentiodynamic polarization techniques using rotating disk electrodes (RDF!.s) in sulphuric acid media containing benzotriazole (BTAH), in aerated and deaerated solutions. The adsorbed passive film obeys the Langmuir isotherm and the equilibrium eonstant for its adsorption increases with increasing copper content of the metal surfaces investigated. The in situ Raman spectra of the 8S/15 and 67/33 brasses iu 0.5 M H,SO, solutions containing BTAH are also presented. By comparison of the in situ Raman spectra with the Raman spectra of [Cu(I)RTA], and [ZnrBTA4],, polymeric complexes, the protective fii has been characterized as being composed of multilayers of the [Cu(I)BTA], complex. The time and potential dependence of the in situ Raman spectra show that the spectra from the surface species are not surface enhanced.

This work presents an experiment done for chemistry students about the effect of the nature of the electrolyte and the nature of the interface on the hydrogen evolution reaction by electrolysis. Two techniques are suggested: method A -two identical copper electrodes in a direct current circuit and method B -three different electrodes in a dc potentiostatic circuit, with copper electrode (working), platinum electrode (counter) and silver-silver chloride-KCl sat electrode (reference). The hydrogen evolution was observed using the A technique by increasing potentials between the two electrodes and the visual observation of the gas production at the cathode. The results showed "semi-quantitative" effect of the pH on the hydrogen evolution. It was observed a larger potential difference in alkaline medium than in acid medium. The results obtained with the B technique from polarization curves showed quantitatively the thermodynamic effect of the pH in addition to the least catalytic effect of copper presented in alkaline medium when compared to copper in acid medium for hydrogen evolution. The technique A can be used in technical courses, high school and general chemistry class for under graduate students. The technique B is appropriate for under graduate electrochemistry class and graduate students.

The nature of the protective film formed by benzotriazole (BTAH) on the surface of the 90/10 CuNi alloy in deaerated 0.5 mol L À1 H 2 SO 4 solution containing Fe(III) ions as oxidant was investigated by weight-loss, calorimetric measurements, and by surface-enhanced Raman spectroscopy (SERS). The SERS measurements show that the protective film is composed by the [Cu(I)BTA] n polymeric complex and that the BTAH molecules are also adsorbed on the electrode surface. A modification of the BET isotherm for adsorption of gases in solids is proposed to describe the experimental results obtained from weight-loss experiments that suggest an adsorption in multilayers. Electrochemical studies of copper and nickel in 0.5 mol L À1 H 2 SO 4 in presence and absence of BTAH have also been made as an aid to interpret the results. The calculated adsorption free energy of the cuprous benzotriazolate on the surface of the alloy is in accordance with the value for pure copper.

Glycerol Stearate (GS) was investigated as a corrosion inhibitor via weight loss on zinc (Zn) metal inside 1.0M hydrochloric acids (HCl). Different electrochemical techniques such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and characterization methods were used in the study. Weight loss measurements and inhibition efficiency (IE) were used to calculate the amount of weight loss and to scrutinize the effect of inhibition concentration on the metal in HCl, and it demonstrated that weight loss decreased as the inhibition concentration increased, and percentage inhibition efficiency increased with increasing inhibition concentration. The Corrosion rate ( ρ ) was calculated, and it was observed that it decreased with the increasing inhibition concentration but increased with an increase in temperature. The compound of inhibitor effectively prevented corrosion by becoming adsorbed to the metal surface and was confirmed by Fourier transform infrared spectroscopy (FTIR). Free Gibbs energy (FGE) demonstrated a spontaneous corrosion process at the metal surface of zinc and the scanning electron microscope (SEM) was used to investigate the surface morphology of the protective layer and confirmed that the adsorption of glycerol stearate was via physisorption adsorption. The adsorption of glycerol stearate on the metal surface was found to follow the Langmuir adsorption isotherm model.

There is an interest in the cement industry in the use of steel slags in cement, but chemical and/or pyrometallurgical modifications are necessary to reduce the free CaO, MgO, and iron contents. However, the potential effects of its application in the reinforcement corrosion, whether in solid (concrete) or liquid medium (pore water), have not yet been addressed. In this context, the present study shows a corrosion analysis of the CA-50 steel in pore water medium extracted from cement pastes with 25% by weight of steel slag, in natural state or pyrometallurgical modified, by means of polarization curves, electrochemical impedance spectroscopy (EIS), and microstructural analysis. For comparison, tests were performed in pore waters presented in literature and representative from Ordinary Portland Cement (OPC) or activated Blast Furnace Slag (BFS) and, to simulate aggressive conditions, 1.0% NaCl was also added to the solutions. The steel remained passive in all media without 1.0% NaCl,...

Male animals often change their behavior in response to the level of competition for mates. Male Lincoln's sparrows (Melospiza lincolnii) modulate their competitive singing over the period of a week as a function of the level of challenge associated with competitors' songs. Differences in song challenge and associated shifts in competitive state should be accompanied by neural changes, potentially in regions that regulate perception and song production. The monoamines mediate neural plasticity in response to environmental cues to achieve shifts in behavioral state. Therefore, using high pressure liquid chromatography with electrochemical detection, we compared levels of monoamines and their metabolites from male Lincoln's sparrows exposed to songs categorized as more or less challenging. We compared levels of norepinephrine and its principal metabolite in two perceptual regions of the auditory telencephalon, the caudomedial nidopallium and the caudomedial mesopallium (CMM), because this chemical is implicated in modulating auditory sensitivity to song. We also measured the levels of dopamine and its principal metabolite in two song control nuclei, area X and the robust nucleus of the arcopallium (RA), because dopamine is implicated in regulating song output. We measured the levels of serotonin and its principal metabolite in all four brain regions because this monoamine is implicated in perception and behavioral output and is found throughout the avian forebrain. After controlling for recent singing, we found that males exposed to more challenging song had higher levels of norepinephrine metabolite in the CMM and lower levels of serotonin in the RA. Collectively, these findings are consistent with norepinephrine in perceptual brain regions and serotonin in song control regions contributing to neuroplasticity that underlies socially-induced changes in behavioral state.

Male animals often change their behavior in response to the level of competition for mates. Male Lincoln's sparrows (Melospiza lincolnii) modulate their competitive singing over the period of a week as a function of the level of challenge associated with competitors' songs. Differences in song challenge and associated shifts in competitive state should be accompanied by neural changes, potentially in regions that regulate perception and song production. The monoamines mediate neural plasticity in response to environmental cues to achieve shifts in behavioral state. Therefore, using high pressure liquid chromatography with electrochemical detection, we compared levels of monoamines and their metabolites from male Lincoln's sparrows exposed to songs categorized as more or less challenging. We compared levels of norepinephrine and its principal metabolite in two perceptual regions of the auditory telencephalon, the caudomedial nidopallium and the caudomedial mesopallium (CMM), because this chemical is implicated in modulating auditory sensitivity to song. We also measured the levels of dopamine and its principal metabolite in two song control nuclei, area X and the robust nucleus of the arcopallium (RA), because dopamine is implicated in regulating song output. We measured the levels of serotonin and its principal metabolite in all four brain regions because this monoamine is implicated in perception and behavioral output and is found throughout the avian forebrain. After controlling for recent singing, we found that males exposed to more challenging song had higher levels of norepinephrine metabolite in the CMM and lower levels of serotonin in the RA. Collectively, these findings are consistent with norepinephrine in perceptual brain regions and serotonin in song control regions contributing to neuroplasticity that underlies socially-induced changes in behavioral state.

Nowadays, with the rapid increase of people's living standards, they paid more attention to food safety. a new method to detect food additives and bacteria is urgently needed. MOFs are a great material to be used to make a chemosensory of their high stability and porous structure. Compared to the MOFs sensor with any other sensors, it is more convenient, fast and sensitive. It shows excellent potential for the detection of food safety issues in the future. In this article, the important research significance of MOF in the field of food containers was introduced. Various methods of preparing MOFs, including the hydrothermal method, diffusion method and solvent-free method are introduced. Then present the influencing factors of MOFs materials from their fluorescence properties and heavy metals. Finally, the detection of coffeic acid, nitrite and carbendazim by MOF electrochemical sensor in the food safety field has been extended and evaluated. Aiming to connect the MOFs-based chem...

Recently, niobium-based oxides have attracted increasing interest as a potential choice for lithium-ion battery technology. The mixed oxide of niobium and titanium, in the composition of TiNb2O7, has been considered a promising candidate for the anodic materials of new generation lithium-ion batteries. However, its precursors require a severe and costly purification process since they are processed from complex ores. In addition to the purification cost, these steps result in significant amounts of acid and alkaline effluents, which generate additional costs for their treatment. The present research was designed to understand the influence of contaminants commonly found in ores or inserted in the process routes to obtain niobium oxides. Iron, potassium, phosphorus, tantalum, and fluoride were inserted into the TiNb2O7 synthesis process from ultrapure solutions. The mixed oxides obtained were subjected to characterizations by the X-ray diffraction technique, scanning electron microsc...

In this paper, we tried to find answers to safety problems due to use of transition metal oxide as positive electrodes in the lithium ion batteries. The exothermic reaction at high temperature induced by the contact between positive electrode in the charged state, such as LiNi 0.8 Co 0.2 O 2 and the liquid electrolyte solution based of LiPF6 (EC, DMC) is reduced by formation of ceramic oxide. Al 2 O 3 -and ZnO-coated are synthesized on the surface of LiNi 0.8 Co 0.2 O 2 particles by chemical vapor deposition. The influences of deposit on the properties of starting material, in particular the thermal stability, are characterized by using, X-ray diffraction, electrochemical measurements and differential scanning calorimeter (DSC). Al 2 O 3 -coated sample show fading specific capacity during the first cycle. However, after several cycles a retention capacity is observed. ZnO-coated LiNi 0.8 Co 0.2 O 2 is inactive electrochemically as shown by X-rays diffraction pattern by the existence of two phases. With regard to DSC analysis in Al 2 O 3 -coated, one observe about 35% of reduction of heat flow during the exothermic reaction. The CVD method must be improved to obtain interesting results with regard to the electrochemical performances of treated material.

The energy storage performance of one of the lightest-known MXenes, Ti 2 CT x (MX) combined with carbon nanospheres (CNS) has been investigated as a symmetric electrode system in an aqueous electrolyte (1 M Li 2 SO 4 ). The energy storage properties were interrogated using cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL), electrochemical impedance spectroscopy (EIS) and voltage-holding tests. The combined material (MX/CNS) demonstrated a higher specific capacity compared to each of the individual components. The material was fabricated with relatively high and low mass loadings, assembled into a symmetric device and performance compared. Specific capacitance, specific power and specific energy for the lower electrode mass loading of 180 F•g -1 , 37.6 kW•kg -1 and 14.1 W•h•kg -1 were all higher than 86 F•g -1 , 20.1 kW•kg -1 and 6.7 W•h•kg -1 for the higher mass loading. A wide voltage window of 1.5 V was obtained, but with limited long-term cycling behavior, suggesting the need for future improvement. Mathematical modelling and simulation of the supercapacitor showed good correlation with the experimental results, validating the model. The results reveal the potential of the Ti 2 CT x to be employed as a viable energy storage system for lightweight applications.

Self-discharge is known to have considerable adverse effects on the performance and application of electrochemical capacitors (ECs). Thus, getting clear understanding of ECs self-discharge mechanisms during charge and discharge process as well as on storage condition is the only solution to ECs self-discharge problems.

Titanium-manganese oxide composites as suitable material for electrode in electrochemical capacitors application was synthesized using spark plasma sintering technique. The feedstock powders were blended at varied compositions in a Turbula mixer through dry mixing with and without the alumina balls. The blended powders were then consolidated at a sintering temperature of 1200 °C with a constant pressure of 25 MPa and holding time of 5 min. The density, phase composition, microstructure, hardness and electrochemical stability of the resulting materials were investigated. Relative densities of 99.33% and 98.49% were obtained for 90TiO2-10MnO2 and 80TiO2-10MnO2 when ball was incorporated. The 90TiO2-10MnO2 powder mixed with balls had its Vickers hardness value increase from 924.4 HV to 998.2 HV. The electrochemical performance of the TiO2 was improved with the addition of MnO2.

Ti-V-W-O/Ti oxide electrodes prepared by a dip coating method provided a fairly large pseudocapacitance both in H 2 SO 4 and KOH solutions. The vanadium penetrates easily into the titanium oxide to form rutile Ti x V y O 2 aided by the tungsten species. These electrodes seem to have a potential for use as electrochemical capacitors.

Inhaled nitric oxide (iNO) is widely used in the treatment of pulmonary hypertension while inhaled NO donors have been suggested as an alternative therapy. The differential susceptibility to inactivation by oxidative stress and oxyhaemoglobin of NO and two NO donors, sodium nitroprusside (SNP) and S‐nitroso‐N‐acetyl‐penicillamine (SNAP) were analysed in isolated endothelium‐denuded pulmonary arteries from 2‐week‐old piglets stimulated with U46619. NO, SNAP and SNP relaxed the arteries (pIC30=7.73±0.12, 7.26±0.17 and 6.43±0.13, respectively) but NO was not detected electrochemically in the bath after the addition of SNP and only at concentrations at which SNAP produced more than 50% relaxation. The sGC inhibitor ODQ (10−6 M) or the sarcoplasmic Ca2+‐ATPase thapsigargin (2×10−6 M) markedly inhibited the relaxation induced by NO, SNAP and SNP. Addition of oxyhaemoglobin (3×10−7 M) or diethyldithiocarbamate (1 mM) markedly inhibited NO‐ (pIC30=6.88±0.07 and 6.92±0.18, respectively), wea...

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