Anodic Direction Research Articles

Indium Oxide Layer Dual Functional Modified Bismuth Vanadate Photoanode Promotes Photoelectrochemical Oxidation of Water to Hydrogen Peroxide.

The photoelectrochemical (PEC) dual-electron pathway for water oxidation to produce hydrogen peroxide (H2O2) shows promising prospects. However, the dominance of the four-electron pathway leading to O2 evolution competes with this reaction, severely limiting the efficiency of H2O2 production. Here, we report a In2O3 passivator-coated BiVO4 (BVO) photoanode, which effectively enhances the selectivity and yield of H2O2 production via PEC water oxidation. Based on XPS spectra and DFT calculations, a heterojunction is formed between In2O3 and BVO, promoting the effective separation of interface and surface charges. More importantly, Mott-Schottky analysis and open-circuit potential measurements demonstrate that the In2O3 passivation layer on the BVO photoanode shifts the hole quasi-Fermi level towards the anodic direction, enhancing the oxidation level of holes. Additionally, the widening of the depletion layer and the flattening of the band bending on the In2O3-coated BVO photoanode favor the generation of H2O2 while suppressing the competitive O2 evolution reaction. In addition, the coating of In2O3 can also inhibit the decomposition of H2O2 and improve the stability of the photoanode. This work provides new perspectives on regulating PEC two/four-electron transfer for selective H2O2 production via water oxidation.

Green Voltammetric Detection of Ophthalmic Drug Nepafenac Using Pencil Graphite Electrode as a Responsive Disposable Electrochemical Sensor

AbstractIn this study, the electrochemical properties of nepafenac, used after eye surgery operations, were investigated on a disposable pencil graphite electrode. Cyclic and square wave voltammetry techniques were used to investigate the electrochemical properties of nepafenac. Two peaks at potentials of approximately +0.33 V and +1.03 V in the anodic direction and two peaks at potentials of approximately +0.29 V and +0.08 V in the cathodic direction were observed on the surface of the disposable pencil electrode in acetate (pH 4.8) medium with the cyclic voltammetry technique. The analytical performance of the developed voltammetric technique had good linearity in the concentration range of 0.30 µM to 3.5 µM at pH 4.8. The LOD value of this voltammetric method in acetate (pH 4.8) medium was calculated as 0.035 µM (8.90 ng mL−1). For reproducibility, the relative standard deviation (RSD) values for Ia and IIa anodic peak current/potential were found to be 1.45%/0.43% and 1.28%/0.25%, respectively. The voltammetric method was successfully applied to urine and pharmaceutical preparations and the results were compared with the spectrophotometric method.

Electrodeposition of Zn-Cr Alloys: A Comparison with Pure Zinc

The electrodeposition of zinc coatings is one of the most common surface treatments for providing corrosion resistance to metallic components. From the thermodynamic point of view, zinc is located in a sweet spot, with its reduction potential being lower than most other common metals, while at the same time being not too susceptible to atmospheric corrosion; overall these features make zinc the ideal candidate for the electroplating of sacrificial coatings for corrosion protection. Owing it to its low cost and scalability, zinc electroplating has cemented itself as a cornerstone process in a variety of industrial sectors in the last decades. [1]While zinc coatings corrosion resistance has proved to be satisfactory in most cases, it could still be improved to operate even in more aggressive environments. For this purpose, electrodeposition of zinc alloys with transition metals from the iron group (Ni, Co, Fe) has proven to be a successful method to enhance zinc coatings corrosion resistance. In particular, zinc-nickel alloys have found the greater success among them, due to improved corrosion resistance and mechanical properties. [2]Zinc-chromium alloys also present a good opportunity to improve coatings performance, thanks to the passivating effect of Cr. In fact, electrodeposited ZnCr alloys with a Cr content up to 10.4% were found to exhibit a corrosion potential shifted by up 150 mV in the anodic direction with respect to the pure zinc counterpart. [3] This shift led to a significant decrease in the coating dissolution rate but was sufficiently small that the layers could still preserve their sacrificial nature towards the underlying steel.In this work, ZnCr coatings are deposited on low carbon steel from an acidic sulfate formulation containing Cr(III) ions at various concentrations. The properties of ZnCr coatings are explored by varying the most common parameters such as current density, composition, and pH. Furthermore, the resulting coatings are characterized through conventional surface analysis techniques such as SEM, EDS, XRD and XRF. Finally, the corrosion resistance performance of the ZnCr coatings is compared to pure Zn coatings to highlight the benefits of the alloy.Bibliography[1] R. Winand, “Electrodeposition of Zinc and Zinc Alloys,” Mod. Electroplat. Fifth Ed., pp. 285–307, Feb. 2011.[2] N. Lotfi, M. Aliofkhazraei, H. Rahmani, and G. B. Darband, “Zinc–Nickel Alloy Electrodeposition: Characterization, Properties, Multilayers and Composites,” Prot. Met. Phys. Chem. Surfaces, vol. 54, no. 6, pp. 1102–1140, Nov. 2018.[3] V. Chakarova, T. Boiadjieva-Scherzer, D. Kovacheva, H. Kronberger, and M. Monev, “Corrosion behaviour of electrodeposited Zn-Cr alloy coatings,” Corros. Sci., vol. 140, pp. 73–78, Aug. 2018.

On the Scope of the Oxygen Plasma Treatment on FTO Electrodes for Electrochemical Processes

The cleaning and/or activation of electrodes for electrochemical purposes using the oxygen plasma treatment has been widely used because of its proven effectiveness to improve the properties of electrodes. Beyond its cleaning effect, the plasma can either create stepped and functionalized carbon-based materials which are active for specific electroanalytes and increase their capacitance [1]. Prussian Blue can also be activated by creating oxygen rich sites thus enhancing its electrochromism [2]. In the case of transparent conductive oxides (TCOs) electrodes such as FTO and ITO-coated glass this treatment has proven to be suitable in the preparation of spray-pyrolyzed titania thin films used as blocking hole layer or electron transporting layer in efficient third generation solar cells [3]. However, the role of this treatment on TCOs when used for electrochemical purposes has not been deeply explored yet. The reason to carry out this study lies in the great number of electrochemical processes that are usually employed for the growth of wide and middle band gap semiconductor metal oxides and chalcogenides with applications in photoelectrochemical and photovoltaic cells [4].To assess the role of the oxygen plasma, FTO was chosen as TCO reference material and the effect of different time exposure and power of plasma was analysed by electrochemical polarization in aqueous media for both anodic and cathodic directions. In the former, PbO2 electrodeposition and oxygen evolution reaction (OER) were considered. In the later, hydroxide generating reactions that usually precipitate in presence of transition metal cations were studied: i) the oxygen reduction reaction (ORR, Figure 1), ii) hydrogen peroxide reduction. Further, the reduction of S8 in DMSO media to sulphide ion was also considered as an aprotic media to growth chalcogenides. Interestingly, all these electrochemical reactions exhibited an increased activation overpotential. The behaviour of treated FTO for OER demonstrated the as implanted oxyanions do not act as source of molecular oxygen as previously claimed [5]. This was verified by the poorly response of ORR after anodic polarizations in acid media.Besides, contact angle measurements allowed to estimate the energetic of the FTO surfaces being these energies correlated with open circuit potential values. Capacitance (Mott-Schottky plots), XPS, UPS and UV-Vis spectroscopy were used to study the semiconductor energy levels of both treated and untreated FTO electrodes. The oxyanion implantation in the oxygen vacancies would be responsible of the sharply diminution of the ORR wave. However, the electrochemical response of the well-known Ferri/Ferro couple only suffered changes under highly aggressive treatments, i.e. for long times or power. Meanwhile, XRD data has shown only slight changes in the structural features of FTO. We can conclude that oxygen plasma treatment is not suitable in FTO for electrochemical purposes, contrary to other deposition methods. Surprisingly, an exception in metals deposition (Ni and Zn) was found.

Decoupled Electrolysis: A Novel Method for Water Splitting Using WO3 Auxiliary Electrode

More emphasis must be placed on the use of clean and renewable energy sources. Production of electricity using solar, wind geothermal etc is becoming more widespread however these types of energy production suffer from intermittence in production and a mismatch of production and consumption cycles. These problems result in a need for an energy storage medium. A hydrogen is a viable option because of its high gravimetric heat capacity (143 MJ/kg) and low flashpoint (-231°C) [1]. For now, most of the produced hydrogen is from hydrocarbons and only 4% is being produced using electrolysis. Hydrogen production via electrolysis is an efficient way how to store surplus energy from renewable energy sources but electrolysis must be made more achievable. Commonly used water electrolysis is limited by the need for complicated gas distribution systems to avoid mixing of H2 and O2 which can lead to a serious safety hazard. Membranes and diaphragms can solve gas mixing problems but they significantly reduce efficiency and increase hydrogen production costs.Here we demonstrate the principle of decoupled electrolysis where oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is separated in space with the use of a WO3 redox mediator. WO3 was produced by the solvothermal method. In accordance with SEM (Fei, NanoSEM 650), XRD (Rigaku, Ultima+) and XPS (Thermo Scientific, Escalab Xi+) data, monoclinic WO3 nanosheet assemblies with a cluster size of 10-20 μm and plate thickness of 50-100 nm were produced without lower oxidation states. Electrodes were produced using carbon felt which was saturated with ink suspension containing active material (WO3), carbon black and polyvinyl difluoride (PVDF) in a mass ratio of 60-30-10. DMF was used as a solvent. Electrolysis was achieved in a two-step process. In the first step, an OER reaction occurs and the H ion is intercalated into WO3 forming tungsten bronze HxWO3. OER reaction occurs on platinum and O2 is released with gas purity above 99.9 %. In the second step, H ion deintercalation occurs and H2 is released at the Pt electrode with a purity greater than 99.9%. Gas purity was determined using a gas mass spectrometer. Electrochemical measurements were performed using Metohm AutoLAB potentiostat with Nova software. The electrode was analysed using cyclic voltammetry (CVP), impedance spectroscopy (EIS) and chronopotentiometry. 0.5 M H2SO4 was used as an electrolyte solution.In accordance with the CVP capacity of the WO3 electrode reaches 325 F/g at a scan rate of 2 mV/s and decreases with an increase in scan speed. A decrease in capacity due to an increase in scanning speed can be associated with limited charge diffusion [2]. The shift of the maximum in the anodic direction associated with the transition from W5+ to W6+ with an increase in scan speed is polynomial and can be associated with the pseudocapacitive behaviour of electrode material. The Nyquist plot from EIS measurements shows the formation of an incomplete arc in the high-frequency interval and linear correlation in lower frequencies. In chronopotentiometry with a current density of 100 mA/g faradaic efficiency reached 90.2% and increased to 100% when 1000 mA/g were used, however taking into account both OER and HER reactions, cycle efficiency decreased from 65 to 43 % with the same current densities. If only HER reaction is analysed when hydrogen is being released and deintercalation happens, cycle efficiency reaches 341 %. High efficiency can be explained by extra energy obtained from the building potential of the WO3 electrode that lowers the standard potential for water electrolysis. Long-term tests showed good stability and no degradation was observed in accordance with SEM and XPS studies. At high intercalation-deintercalation cycle times, a non-Faradaic process can be observed which reduced HER cycle time. A spontaneous deintercalation can be observed. One of the future goals is to prevent this process by the use of different auxiliary electrode materials.[1]-Tashie-Lewis BC, Nnabuife SG. Hydrogen production, distribution, storage and power conversion in a hydrogen economy - a technology review. Chemical Engineering Journal Advances 2021;8:100172.[2]- Das AK, Karan SK, Khatua BB. High energy density ternary composite electrode material based on polyaniline (PANI), molybdenum trioxide (MoO3) and graphene nanoplatelets (GNP) prepared by sonochemical method and their synergistic contributions in superior supercapacitive performance. Electrochim Acta 2015;180:1e15. Figure 1

Electrochemical Sensor Design Based on Silver Nanoparticles Modified Multiwalled Carbon Nanotubes Paste Electrode for the Sensitive Determination of Mepivacaine.

Mepivacaine, an amide-type local anesthetic drug widely used in regional anesthesia, was studied by some aspects such as electrochemical behavior, mechanism illumination, and analytical applications by cyclic voltammetry (CV) and different pulse voltammetry (DPV) methods. In this study, a novel, fast, simple, portable, and the inexpensive electrochemical sensor was developed for the determination of mepivacaine. This study was carried out by mepivacaine anodic direction detection for the first time. The modified sensor was fabricated with silver nanoparticles (AgNP) and multiwalled carbon nanotubes paste electrode (MWCNTPE) by using the drop-dry method. Different experimental parameters, such as pulse amplitude, step potential, and scanning rate in the DPV application module, were optimized. Under optimal operation conditions, the limit of detection (LOD) as low as 31 μg L-1 was found over the dynamic range (0.1-8.0 mg L-1). In contrast to its high response towards mepivacaine, the DPV exhibits negligible responses on modified AgNP/MWCNTPE when exposed to interfering species such as dopamine, uric acid, glucose, ascorbic acid, and some heavy metals. Exceptionally, the proposed DPV method on modified AgNP/MWCNTPE was successfully applied to pharmaceutical dosage form and synthetic human serum with a low relative standard deviation (RSD) of 1.35% and 2.02%, respectively.

A study on redox reactions of the azo dye Sudan I and its hydroxylated metabolites on pyrolytic graphite and boron doped diamond electrodes to support electrochemical studies of metabolic transformations

Sudan I (1-(Phenyldiazenyl)naphthalen-2-ol) is an orange industrial azo dye. It is utilized as a marker substrate in studies of metabolic transformation of xenobiotics through processes involving cytochrome P450 hydroxylase. In this complex study, redox and subsequent chemical/electrochemical reactions of Sudan I and its three major metabolites (4′‑hydroxy, 6‑hydroxy, and 4′,6-dihydroxy derivatives of Sudan I) were investigated using boron doped diamond and basal plane pyrolytic graphite electrodes. Cyclic voltammetry (CV) in Britton – Robinson buffer pH 7 showed distinct differences in the number and potential of signals, depending on the number and positions of the hydroxy groups. While in CV scans initiated in anodic direction, primary oxidations of paired or unpaired hydroxy groups are dominating, cathodic scans lead primarily to reduction of the azo group and to cleavage of the parent compounds and formation of 1-aminonaphthalen-2-ol and aniline or their corresponding hydroxylated derivatives. These are oxidizable in reverse anodic scans. Combinations of CV scans can be used to distinguish among all tested compounds. Basal plane pyrolytic graphite electrode provides better sensitivity than boron doped diamond electrode due to enhanced adsorption of the aromatic analytes/intermediates. The possibility of detecting Sudan I and its metabolites in the presence of excess amounts of NADPH as an essential component of enzymatic hydroxylation systems, was tested. Although the oxidation signal of NADPH partially interferes with signals of primary oxidation of hydroxy groups (particularly for Sudan I), our results suggest that electrochemical assays could be applicable in monitoring transformation of Sudan I in biochemical studies.

Plasma Electrolytic Oxidation on Magnesium AZ31 with Sepiolite as Inhibitor Carrier for Improved Corrosion Protection

Plasma electrolytic oxidation (PEO) in an alkaline silicate electrolyte containing nanosized sepiolite fibers was carried out on magnesium alloy AZ31. The mineral fibers were loaded with different corrosion inhibitors and incorporated in situ during the PEO treatment. The composition and microstructure of the PEO coatings were investigated by SEM. It was shown that the fibers are located on the surface as well as inside the “weak spots” of the coating, i.e., pores and discharge channels. The fixation of the particles is caused by sintering due to the heat developed during the PEO treatment. Investigations using electrochemical impedance spectroscopy and linear sweep voltammetry in 0.01 M NaCl solution confirmed an improvement of the corrosion protection. The use of the inhibitors shifts the critical pitting potential in the anodic direction. Regarding efficiency, cerium-loaded sepiolite showed the best behavior by shifting the pitting potential by +0.9 V.

Photoelectrochemical and Photovoltaic Performance of As-deposited Ink-based CuInS2 Heterojunction Thin Film

In this report, we demonstrate low-temperature ink-based fabrication of CuInS2-based photoelectrodes for hydrogen production capable of producing photocurrent densities as high as 8.8 mA.cm−2. In this process, molecular ink made of metal chlorides and thiourea dissolved in methanol was spin coated onto Mo-coated soda lime glass substrates. Samples were then placed on a hot plate (sample surface temperature: 250 °C) to induce CuInS2 formation and remove the solvent and by-products. No further processing, such as high temperature sulfurization, was performed. The CuInS2 films were then integrated as photocathode for hydrogen evolution by photoelectrodeposition of Pt nanoparticles. Photocurrent density of 0.4 mA.cm−2 at 0 V vs. RHE was detected from such electrodes. However, samples coated with CdS/ZnO/ITO overlayers forming heterojunction prior to Pt deposition exhibited significant improvement of the photocurrent density, reaching 8.8 mA.cm−2 at 0 V vs. RHE, highlighting the improved charge transfer by the p-n junction formed at the CuInS2/CdS interface. The charge transfer resistance of the CuInS2/CdS/ZnO/ITO-Pt photoelectrode was almost 5 times lower than that of the CuInS2-Pt photoelectrode as revealed by electrochemical impedance spectroscopy analysis. In addition, the onset potential was shifted by ca. 0.45 V toward the anodic direction, reaching 0.75 V vs. RHE. Solar cell made of identical structure (Mo/CuInS2/CdS/ZnO/ITO) showed power conversion efficiency of 2.1% with short-circuit photocurrent density and open circuit voltage of 7.4 mA.cm−2 and 820 mV, respectively.

Carbon anode of intercalation capacitive coupling mechanism enabling long term potassium ion capacitors at low temperature

Low temperature comprehensive performance of the dominating lithium ion batteries (LIBs) is a matter of increasing concern. In this work, we screen typical carbon anodes with different structural features such as interlayer spacing, degree of graphitization, porosity, and specific surface area, for sustainable potassium ion capacitors (PICs) at −20 °C. Graphene nanosheet (GN) exhibits much better K+ storage performance over the other carbon materials including graphite, activated carbon, and hard carbon, which is ascribed to the synergistic effects of high conductivity, enlarged interlayer spacing, moderate specific surface area, mesopore structure, and short K+ diffusion path. This screening guides a design direction of carbon anode for K+ storage device at low temperature. Meanwhile, the electrolyte additive of Cs cation could be preferably reduced at the surface of GN during the potassiation, which enables a thin and robust solid electrolyte interphase (SEI) layer and effectively suppresses the co-intercalation induced GN exfoliation and electrolyte decomposition, giving rise to improved cyclic stability at −20 °C. The assembled PICs based on the GN anode and optimized electrolyte enable a comprehensive low temperature performance, especially long-term stability (2000 cycles) over batteries, demonstrating a reliable electrical energy storage device at low temperature.

Determination of H2O/H2 system exchange current densities on cycled hydride electrodes from overswitch potential jump at low and high charge/discharge rates

This research paper describes a simplified and quick method for determining the exchange current densities of the H2O/H2 system on powder composite electrodes made of hydrogen storage intermetallics.The method is based on the hydrogen storage electrode potential jump upon its galvanostatic overswitching from the cathodic to the anodic direction for low- and high charge/discharge rates. Indeed, research findings indicate that the discharge rate/exchange current density quotient depends either linearly or exponentially on the potential jump for low- and high-charge/discharge rates. This study also defines the applicability ranges for both types of dependencies with the best accuracy for calculating exchange currents (relative experimental error ≤5%) corresponding to potential jumps of up to 0.037 V (discharge rates of up to 0.2C) and 0.08–0.20 V (discharge rates over 0.3C). Furthermore, this study presents other instances of determining exchange currents versus cycling determination for different intermetallics and discusses the effect of the hydride material surface modification and charge/discharge rate conditions on the exchange current density.

Electrocatalytic hydrogen evolution with a copper porphyrin bearing meso-(o-carborane) substituents.

A newly designed copper complex of 5,15-bis(pentafluorophenyl)-10,20-bis(o-carborane)porphyrin (1) was synthesized and tested for the electrocatalytic hydrogen evolution reaction (HER). In acetonitrile, 1 was much more efficient than Cu 5,15-bis(pentafluorophenyl)-10,20-diphenylporphyrin (2) for electrocatalytic HER by shifting the catalytic wave to the anodic direction by 190 mV. In aqueous media, 1 also outperformed 2 by achieving higher current densities under smaller overpotentials. This enhancement was attributed to the aromatic and the strong electron-withdrawing properties of o-carborane groups. This work is significant to address the crucial effects of meso-(o-carborane) substituents of metal porphyrins on boosting the electrocatalytic HER.

Highly Stable Lithium Metal Anode Constructed by Three-Dimensional Lithiophilic Materials

Although lithium metal anode has irreplaceable advantages, such as ultra-high specific energy density and ultra-low redox potential, a variety of issues, i.e., short cycle life, low Coulomb efficiency, and tendency to cause fire explosions caused by lithium dendrite growth and high reactivity to the electrolyte, seriously hinder the practical progress of lithium metal anode. This perspective summarizes how 3D lithiophilic materials have stabilized lithium metal anodes in recent years by improving the uneven deposition of lithium metal, alleviating the volume expansion of lithium metal anodes, and limiting dendrite growth. Simultaneously, the issues of the 3D composite lithium anodes in practical application are concluded and the research direction of 3D composite lithium anode is prospected.

A novel approach to determine cathodic passivation characteristics and semiconducting properties of pure aluminium 99.5 wt% and aluminium alloy 7075-T6 with an electrochemical pen electrode

Localised electrochemical impedance spectroscopy and Mott-Schottky analysis were carried out to investigate the electrochemical behaviour of pure aluminium 99.5 wt% and aluminium alloy 7075-T6. Functionally graded surface films were generated using a Hull cell set-up, with the nature of the resulting surface assessed as a function of cathodic current density. Defect donor densities, oxide thicknesses, and impedance moduli were determined, resulting in sub-mm to mm-sized response characteristics. Mott-Schottky analysis provided access to n-type characteristics in the cathodic polarisation regime and p-type behaviour towards the anodic polarisation direction. Electron microscopy analysis of the contact area revealed the occurrence of localised corrosion.

Second‐harmonic generation technique for in situ study of passive film formation on carbon steel surfaces in aqueous solutions

AbstractThe aim of this work was to revisit second‐harmonic generation (SHG) as a technique for the in situ analysis of oxide film formation on steel samples immersed in aqueous solutions and during electrochemical experiments. The measurements were compared to active reflectance spectroscopy (ARS), which is a more established in situ spectroscopy technique. Carbon steel electrodes were subjected to polarization in pH neutral and mild‐alkaline electrolytes to provoke the formation of passive films. In situ SHG measurements allowed monitoring of compositional changes in the formed film, as the SHG intensity increased in the domain of stability of Fe3O4 and decreased in the domain of stability of Fe2O3 during potentiodynamic polarization. ARS, on the other hand, is suitable to monitor film thickness. ARS absorption increased along with film growth when moving in the anodic direction during potentiodynamic polarization. During 30 min cathodic polarization at −0.9 VAg/AgCl sat. KCl in initially pH neutral the combination of SHG and ARS revealed the presence of an oxide film that was primarily composed of Fe3O4 and with a thickness up to 0.7 nm.

Does anodal cerebellar tDCS boost transfer of after-effects from throwing to pointing during prism adaptation?

Prism Adaptation (PA) is a useful method to study the mechanisms of sensorimotor adaptation. After-effects following adaptation to the prismatic deviation constitute the probe that adaptive mechanisms occurred, and current evidence suggests an involvement of the cerebellum at this level. Whether after-effects are transferable to another task is of great interest both for understanding the nature of sensorimotor transformations and for clinical purposes. However, the processes of transfer and their underlying neural substrates remain poorly understood. Transfer from throwing to pointing is known to occur only in individuals who had previously reached a good level of expertise in throwing (e.g., dart players), not in novices. The aim of this study was to ascertain whether anodal stimulation of the cerebellum could boost after-effects transfer from throwing to pointing in novice participants. Healthy participants received anodal or sham transcranial direction current stimulation (tDCS) of the right cerebellum during a PA procedure involving a throwing task and were tested for transfer on a pointing task. Terminal errors and kinematic parameters were in the dependent variables for statistical analyses. Results showed that active stimulation had no significant beneficial effects on error reduction or throwing after-effects. Moreover, the overall magnitude of transfer to pointing did not change. Interestingly, we found a significant effect of the stimulation on the longitudinal evolution of pointing errors and on pointing kinematic parameters during transfer assessment. These results provide new insights on the implication of the cerebellum in transfer and on the possibility to use anodal tDCS to enhance cerebellar contribution during PA in further investigations. From a network approach, we suggest that cerebellum is part of a more complex circuitry responsible for the development of transfer which is likely embracing the primary motor cortex due to its role in motor memories consolidation. This paves the way for further work entailing multiple-sites stimulation to explore the role of M1-cerebellum dynamic interplay in transfer.

Electrochemical Analysis of Antipsychotic Drug Quetiapine Fumarate Using Multi‐walled Carbon Nanotube Modified Glassy Carbon Electrode

AbstractElectrochemical properties of quetiapine fumarate were examined on the anodic direction with multi‐walled carbon nanotube modified glassy carbon electrode using voltammetric methods. The ratio of multi‐walled carbon nanotube has been optimized using its various concentrations. The oxidation process was found to be irreversible, and adsorption controlled. The linear ranges were determined as 4×10−9–2×10−6 M for differential pulse stripping voltammetry and 2×10−9–2×10−6 M for square‐wave stripping voltammetry with detection limits of 8.07×10−10 and 2.71×10−10 M, respectively. The methods were validated and successfully applied for the analysis of quetiapine fumarate tablets. The groups responsible for the oxidation reaction of quetiapine fumarate were investigated with model substances.

Coherent x-ray radiation induced by high-current breakdown on a ferrite surface

For the first time observed that at the initial stage of a high-current discharge, a low-divergence short (<2 ns) electromagnetic pulse is formed over a ferrite surface. The 50% part of the energy spectrum of this pulse lies in the region of sufficiently hard x-ray radiation (hν > 1 keV) with an energy of 0.6 mJ and an average power of 0.3 MW. The radiation propagates parallel to the surface in the anode direction with the angle divergence <2°. The high directionality of the radiation in absence of the aperture-limiting devices for the radiation beam and the quadratic dependence of the spatial radiation energy flux density on the length of working part of the ferrite prism points to the coherent nature of the observed radiation. A possible generation mechanism of the radiation is proposed. It is based on the short-lived magnetization of the ferrite plots by a high-power electromagnetic pulse and the subsequent coherent interference of unit waves irradiated by these plots.

Hydrothermal modification of TiO2 nanotubes in water and alkali metal electrolytes (LiNO3, NaNO3, KNO3) – Direct evidence for photocatalytic activity enhancement

The influence of hydrothermal annealing (HA) of TiO2 nanotubes (TiO2-NTs) in various baths (H2O, LiNO3, NaNO3, KNO3 performed for 4 h, 24 h, 64 h), on their photocatalytic and photoelectrocatalytic properties, was studied. The use of electrolytes was to enable the monitoring of photoactivity changes as a result of the expected impact on the population of hydroxyl groups on the surface. The assumption turned out to be correct and it was proved that the presence of Li+, Na+ or K+ does not allow achieving the same increases in photoactivity as observed for water. Modified samples exhibit significantly decreased F, P and carbon containing species. The length of the HA annealing time considerably affected the geometry of the nanotubes: eliminated clusters, changing the tilting angle of nanotubes, the wall thickness and inter-nanotube distance. Morphology changes due to HA treatment were associated with the interference phenomenon recorded as maximum in the Vis range. HA treatment in water brings about the most photoactive and photoelectroactive material characterized with minor modification in the optical bandgap and position of the flat bad potential. The optical energy bandgap values for electrodes containing alkali metals were reduced (up to 2.72 eV) and flat-band potential was shifted towards the anodic direction (up to 0.25 V disparity). However, increased activity as photocatalysts in the methylene blue degradation process and higher photocurrent generation was achieved for samples after modification in distilled water than in electrolytes, but these parameters are still better in comparison to unmodified titania nanotubes. Long-term treatment in water and electrolytes reduced threshold potentials for oxygen evolution reaction. The studies confirmed the effectiveness of the hydrothermal method for obtaining better photocatalytic parameters of TiO2-NTs and indicate that the presence of alkali metals is not favourable for maintaining high photocatalytic parameters.

Galvanotactic Migration of Glioblastoma and Brain Metastases Cells.

Galvanotaxis, the migration along direct current electrical fields, may contribute to the invasion of brain cancer cells in the tumor-surrounding tissue. We hypothesized that pharmacological perturbation of the epidermal growth factor (EGF) receptor and downstream phosphatidylinositol 3-kinase (PI3K)/AKT pathway prevent galvanotactic migration. In our study, patient-derived glioblastoma and brain metastases cells were exposed to direct current electrical field conditions. Velocity and direction of migration were estimated. To determine the effects of EGF receptor antagonist afatinib and AKT inhibitor capivasertib, assays of cell proliferation, apoptosis and immunoblot analyses were performed. Both inhibitors attenuated cell proliferation in a dose-dependent manner and induced apoptosis. We found that most of the glioblastoma cells migrated preferentially in an anodal direction, while brain metastases cells were unaffected by direct current stimulations. Afatinib presented only a mild attenuation of galvanotaxis. In contrast, capivasertib abolished the migration of glioblastoma cells without genetic alterations in the PI3K/AKT pathway, but not in cells harboring PTEN mutation. In these cells, an increase in the activation of ERK1/2 may in part substitute the inhibition of the AKT pathway. Overall, our data demonstrate that glioblastoma cells migrate in the electrical field and the PI3K/AKT pathway was found to be highly involved in galvanotaxis.