Cyclic Pulse Research Articles

Rational control of WSe2 layer number via hydrogen-controlled chemical vapor deposition

Tranistion metal dichalcogenides are a promising family of materials for electronics and optoelectronics, in part due to their range of bandgaps that can be modulated by layer number. Here, we show that WSe2 can be selectively grown with one, two, or three layers, as regulated by a one-step hydrogen-controlled chemical vapor deposition (H-CVD) process involving cyclical pulses of H2 flow. The physical and vibrational properties of the resulting mono-, bi-, and tri-layer WSe2 films are characterized by atomic force microscopy and Raman spectroscopy. Modifying the H-CVD process to include more than three H2 pulses results in thicker WSe2 films, however the thickness of these films is not well controlled and feature small, bulk-like pyramidal islands. Transmission electron microscopy analysis reveals that most of these islands exhibit a spiral structure and appear to be grown via screw-dislocation-driven growth, similar to other works. Therefore, the H-CVD process is demonstrated to be a powerful tool for controlling the layer thickness of WSe2, but its practicality is limited to the few-layer regime.

Highly sensitive detection of dopamine, ascorbic and uric acid with a nanostructure of dianix yellow/multi-walled carbon nanotubes modified electrode

Abstract A glassy carbon electrode has been modified with electrochemical polymerization of dianix yellow (PDY) along with multi-walled carbon nanotubes (MWCNTs) and utilized for the selective determination of dopamine (DA), ascorbic acid (AA) and uric acid (UA). AFM and SEM images compared the surface morphology and topography of bare and modified electrodes. The electrochemical activities of DA, AA and UA on the bare and modified electrodes were compared with cyclic, linear sweep, and differential pulse voltammetry (DPV). Large peak separation, good sensitivity and stability allow the PDY/MWCNTs modified electrode to analyzing DA individually and simultaneously in the presence of AA and UA. The DPV data showed DA, AA and UA peak currents are linear in the concentrations ranges of 0.7–2500 nM, 5–110 µM and 0.100–7.500 µM. respectively. Also, the respected detection limits obtained with this method were 0.7, 9.9 and 8.9 nM. The practical analytical application of this modified electrode was demonstrated by DA determination in human blood serum samples.

Chemical Sensor Based on Molecularly Imprinted Organic-Organic Nanocomposite Film for the Analysis of Melamine in Infant Formula

Melamine (MA) is non-edible synthetic chemical intentionally added to foodstuffs such as milk and milk products including infant formula as the fake source of protein. Many evidences confirmed that this molecule is primarily responsible for kidney failure by forming kidney stones and then blocking the renal tubes. Therefore, a simple, sensitive and rapid method for online quantification of MA can avoid the consumption of milk products contaminated with MA and possible health risks resulted both socially and economically. The present work reports the development of a chemical sensor from aniline (ANI) and acrylic acid (AA) copolymer films by using concurrent electrochemical polymerization method using MA as a template. After optimization of important parameters and template removal, the performance of the film formed was studied by cyclic and differential pulse voltammetry. The proposed sensor showed a linear current response with various concentrations of MA. The linear range, limit of quantification and limit of detection were 0.1-200 x10-9 M, 5.73x10-11M, 1.72 x10-11M respectively. The sensitivity and selectivity of the sensor achieved may attribute to the synergistic effect of different functional units found on the polymer composite. These functional units competitively bind the template with non-covalent interactions. The sensor was also applied to analyze milk samples and obtained a recovery of 95.87-105.63% with RSD 1.11-2.23%. The good stability and reusability as well as strong affinity to the imprint molecule make the imprinted copolymers the promising functional materials for future sensor development.

Differential Pulse Voltammetric Determination of Anticancer Drug Regorafenib at a Carbon Paste Electrode: Electrochemical Study and Density Functional Theory Computations

Electrochemical properties of regorafenib (REG) were studied in 0.1 M Britton−Robinson buffer-methanol solutions (3 : 2, v/v) with pH between 3 and 8 at carbon paste electrode by cyclic and differential pulse voltammetry. The results exhibited irreversible anodic peak at about 0.90 V vs. Ag/AgCl, NaCl (3 M). The anodic peak was found to be diffusion–adsorption controlled. Mechanism of REG electrochemical reaction was studied by performing density functional theory computations and mass spectrometric analysis. A validated differential pulse voltammetry (DPV) technique for REG determination was performed. The calibration curve of REG on carbon paste electrode was linear in the concentration range of 0.5–13 μg/mL and limit of detection was 0.10 µg/mL. The recommended DPV method was used to detect REG in spiked plasma and urine specimens and average recoveries were 94%.

Transient Potential Induced Dissolution of Metal Biporlar Plates Used in Proton Exchange Membrane Fuel Cell

Corrosion of metallic bipolar plates (BPPs) under the aggressive working conditions is the major issue that impedes its application in proton exchange membrane fuel cells (PEMFCs). Transient potential is generated during the different operating conditions of PEMFCs such as start-up/shut-down(SU/SD), and dynamic loading stages. Transient potential-induced corrosion is a serious problem encountered by BPPs. To investigate the influence of transient potentials on corrosion of BPPs, potential pulses with different amplitudes are applied to specimens. Also, a novel zirconium oxynitride coating is prepared via atomic layer deposition to improve the stability of BPPs.Results show that transient potentials generated at passive and transpassive potential regions are both detrimental to the stability of BPPs. For the uncoated samples, a larger potential fluctuation in the passive region could induce a much higher frequency of passive film breakdown than that generated by a smaller potential fluctuation during the cyclic pulse tests. In the transpassive region, upon increasing transient potentials, the passive film formed on surface enters the potential dependent dissolution region, leading to severe intergranular corrosion after a certain cycles of pulse tests.The zirconium oxynitride coated samples present improved performance in both normal potentiostatic polarization and transient potential conditions. The enhanced corrosion resistance of coated samples is attributed to the continuous formation of protective oxide layer which has a wider band gap than passive films formed on uncoated samples. Therefore, the coated sample enters the transpassive potential region at a more positive potential and thus exhibits much lower dissolution rate. Moreover, the Mott-Schottky plots suggests that the defect density of the coated samples is much lower than the uncoated counterpart, and the deterioration of uncoated sample performance under different transient potentials is related to the passive film disorder degree.From our study, transient potentials would accelerate the degradation of BPPs, and the development of bipolar plates coated with dense protective surface films could help mitigate the dissolution induced by the transient potentials, thus improving stability and durability of BPPs. Specially, a layer of coating with a wider band gap between Fermi level and valance band is beneficial to reduce the dissolution in the transpassive potential region.

Determination of Methimazole in Pharmaceutical Preparation and Human Serum by Square Wave and Differential Pulse Polarographic Methods

Objectives: In this study, the polarographic behaviour of methimazole was studied using cyclic, square wave and differential pulse polarographic methods. Methods: The influence of several variables (including nature of the buffer, concentration, scan rate, drop size, etc.) was examined in square wave and differential pulse polarographic methods for methimazole. The best square wave and differential pulse polarographic responses were obtained in 0.1 M sulfuric acid. The peak currents were measured with a static mercury drop electrode at 0.10 V versus Ag/AgCl. Results: The linearity was established over the concentration range of 5-80 mg/mLfor both methods in supporting electrolyte and human serum. The methods were validated and applied to the determination of methimazole in a commercial tablet. There was no significant differences between the results obtained by square wave and differential pulse polarographic methods. Square wave and differential pulse polarographic methods are also available and applicable for the determination of mentioned substance in human serum. No electroactive interferences from the endogenous substances were found in the serum samples. Mean recovery was 99.9%. Conclusion: They were concluded that the developed methods were accurate, sensitive, precise, reproducible and useful for the quality control of methimazole in pharmaceuticals and spiked serum.

Electrochemical Sensing of Flutamide Contained in Plasma and Urine Matrices Using NiFe2O4/rGO Nanocomposite, as an Efficient and Selective Electrocatalyst

AbstractIn this article, we report on the synthesis and new employment of magnetic nickelferrite oxide nanoparticles decorated reduced graphene oxide (NiFe2O4/rGO) to electrochemically sensing of flutamide. The preparation of this electrocatalyst was first assessed using various analytical instrumental techniques including FT‐IR spectroscopy, X‐ray diffraction spectroscopy, energy‐dispersive X‐ray spectroscopy, and field emission scanning and transmission electron microscopy. Besides, its electrochemical performance was investigated utilizing some electrochemical methods such as cyclic and differential pulse voltammetry, and also electrochemical impedance spectroscopy. The findings of this research are especially relevant for sensing flutamide in aqueous and biological samples. At the optimized conditions, the electrochemical sensor showed a linear range of 0.24–40.0 μmol L−1, the detection limit of 0.05 μmol L−1 flutamide, calibration sensitivity of 1.016 μA/μmol L−1, and repeatability and reproducibility of 1.7 % and 4.1 %, respectively. The selectivity of the method was investigated in the presence of ions, and species can generally exist in the biological medium. The resulting data of the present work represented that this type of magnetic nanocomposites is suitable for selective detection of flutamide in real samples of plasma and urine. The recoveries obtained for flutamide analyses represented lower than 5.0 percent of relative error in these real samples.

Calcium channel blocker lercanidipine electrochemistry using a carbon black-modified glassy carbon electrode.

Lercanidipine, a third-generation dihydropyridine calcium L-type channel blocker, redox behavior at different carbon electrode materials, in a wide pH range, using cyclic, square-wave, and differential pulse voltammetry, was studied. A comparison was made between unmodified glassy carbon electrode (GCE) and boron-doped diamond electrode (BDDE), and GCE and BDDE modified with a carbon black (CB) nanoparticle embedded within a dihexadecylphosphate (DHP) nanostructured film (CB-DHP/GCE and CB-DHP/BDDE). Lercanidipine oxidation, for 3.4 < pH < 9.5, is an irreversible, diffusion-controlled, pH-dependent process that occurs in two consecutive steps, with the transfer of one electron and one proton, at the N1 and C4 positions in the 1,4-dihydropyridine ring. For pH > 9.5, both oxidation processes are pH-independent and a pKa = 9.40 was determined. Lercanidipine reduction at pH = 7.0 is an irreversible process, and the lercanidipine reduction products are electroactive and follow a reversible electron transfer reaction. Lercanidipine electroanalytical determination, at a nanostructured GCE modified with a CB-DHP film (CB-DHP/GCE), with no need for N2 purging, with a detection limit of 0.058μM (3.58 × 10-5gL-1) and a quantification limit of 0.176μM (1.08 × 10-4gL-1), was achieved. Graphical abstract.

Electrochemical and catalytic assessment of peripheral bromoaryl-substituted manganese and iron porphyrazines

The cyclotetramerization reaction following the Linstead approach led to novel symmetrical magnesium(II) aminoporphyrazines with methyl(6-bromo-3-pyridylmethyl) and methyl(4-bromobenzyl) substituents. These products were applied in the demetallation reaction procedure in trifluoroacetic acid in the dark, which resulted in free-base porphyrazine derivatives. Then these macrocycles were remetallated with iron(II) bromide in DMF to give the desired iron(III) porphyrazine macrocycles. Simultaneously, the cyclotetramerization reaction of maleonitrile derivatives with manganese(II) chloride in n-pentanol and DBU led to symmetrical manganese(III) porphyrazines. New porphyrazine complexes with methyl(6-bromo-3-pyridylmethyl) and methyl(4-bromobenzyl) substituents were thoroughly characterized by the use of various analytical techniques, including electronic spectra, mass spectrometry, and FTIR. Macrocycles were subjected to electrochemical and spectroelectrochemical characterization, accompanied by preliminary catalytic study. The electrochemical properties of all obtained macrocycles were assessed with the use of cyclic and differential pulse voltammetry. The electrochemical activity of new macrocycles and their susceptibility to oxidation/reduction processes depended on the presence of nitrogen substituents in their macrocyclic periphery. The electrochemical measurements provided information on the positions of energy levels (HOMO-LUMO) of each porphyrazine, allowing estimation of the electrochemical energy gaps. The calculated electrochemical energy gaps were higher for porphyrazines with methyl(6-bromo-3-pyridylmethyl)amino peripheral substituents than methyl(4-bromobenzyl)amino ones due to the more electronegative nature of nitrogen amine atom. The calculated electrochemical HOMO-LUMO energy level gap values and the optical band gaps were found to agree within approx. 0.2 eV. Iron(III) and manganese(III) porphyrazines were assessed in terms of their catalytic properties. In these studies, DPBF was employed as a substrate of oxidation processes due to its easy UV–vis assessment. The results revealed the catalytic activity of porphyrazines with peripheral methyl(4-bromobenzyl)amino substituents following first-order kinetics.

Lipoic acid as an efficient and versatile redox catalyst for the electroanalysis of N-acetylcysteine: effects of the electrode nature and insights into the catalytic mechanism

In this work, the boron-doped diamond electrode (BDDE) was used for the electrocatalytic oxidation of N-acetylcysteine (NAC), in the presence of lipoic acid (LipS2), which works as an organic homogenous electrochemical catalyst. Cyclic voltammetry (CV), controlled-potential electrolysis, and differential pulse voltammetry (DPV) were performed in buffered aqueous solution at pH 7.0, in order to study the proposed system. Several analytical figures of merit were obtained for NAC, including a linear response range from 1 up to 100 μmol L−1 and detection limit of 93 nmol L−1. The method was successfully applied to the quantification of NAC in pharmaceutical preparations (capsules, syrup, and suspension), without matrix effects. The present study shows that the redox reaction between the studied thiolate and the electrogenerated cation radical of LipS2, regenerating the original compound, on BDDE, is a promising analytical tool for quantifying NAC, in a relatively low oxidation potential, very simple, rapid, convenient, sensitive, and low-cost way.

Construction of a sensitive electrochemical sensor based on 1T-MoS2 nanosheets decorated with shape-controlled gold nanostructures for the voltammetric determination of doxorubicin.

Aninnovative and portable design to fabricate an electrochemical sensor based on metallic phase MoS2 (1T-MoS2) decorated with shape-dependent gold nanostructures for the determination of doxorubicin (DOX)is presented. In this context, homogenous and uniform single-crystal gold nanospheres (AuNSPs) and nanorods (AuNRDs) were firstly synthesized by seeded growth approach. Afterwards, AuNSPs and AuNRDs were anchored on 1T-MoS2 surfaces to construct the desired electrochemical sensing platform towards the DOX assay. 1T-MoS2 was exfoliated by metal intercalation process using NaK metal alloys. The structure and surface morphology of 1T-MoS2, AuNSPs, and AuNRDs were characterized by XPS, Raman, UV-vis, TEM, and SEM. The electrochemical behavior of DOX using various MoS2-based electrochemical sensors prepared on screen-printed electrode (SPE) was examined by cyclic voltammetry and adsorptive stripping differential pulse voltammetry. The electrocatalytic efficiency of AuNRDs on 1T-MoS2 was also compared with that of AuNSPs on 1T-MoS2, and it showed much better electrocatalytic activity towards the DOX. A nanocomposite prepared with AuNRDs and 1T-MoS2 on SPE (AuNRDs/1T-MoS2/SPE) exhibited a linear relationship between peak current and DOX concentrationin the range 0.01-9.5μM with a detection limit of 2.5nM. The AuNRDs/1T-MoS2/SPE was successfully applied to the sensitive and rapid determination of DOX in spiked human serum samples with satisfactory recoveries in the range 99.2-100.8%. Graphical abstract Schematic representation of a portable design for electrochemical sensor based on shape-controlled gold nanostructures decorated on metallic phase molybdenum disulfide (1T-MoS2) towards the sensitive determination of doxorubicin.

Highly Sensitive Detection of Dopamine, Ascorbic and Uric Acids using Dianix Yellow/Multi-walled Carbon Nanotubes Modified Electrode

A glassy carbon electrode has been modified by electrochemical polymerization of dianix yellow along with multi-walled carbon nanotubes (MWCNTs) and utilized for the selective determination of dopamine (DA), ascorbic acid (AA) and uric acid (UA). Atomic force microscopy and scanning electron microscopy images were obtained to compare the surface morphology and topography of the bare and modified electrodes. Also, the electrochemical activities of DA, AA, and UA on the bare and modified electrodes were evaluated with the use of cyclic, linear sweep and differential pulse voltammetry (DPV). Large peak separation, good sensitivity, and stability allow to apply the poly-dianix yellow/MWCNTs modified electrode for the determination of DA individually and in the presence of AA and UA. The DPV data showed the linearity of DA, AA, and UA peak currents in the concentrations ranges of 7–2500 nM, 5–110 µM, and 0.100–7.500 µM with the detection limits of 6.1, 99 and 8.9 nM, respectively. The proposed electrode was applied for the quantification of dopamine in human blood serum samples.

Sensitive and selective voltammetric oxidation and determination of an antiemetic drug using gold electrode and its biomedical applications

In this study, we investigated the voltammetric oxidation and determination of an antiemetic drug, metoclopramide hydrochloride at gold electrode using cyclic, linear sweep and differential pulse voltammetric (DPV) techniques. The anodic peak was characterized and the process was diffusion-controlled. The influence of current on pH, scan rate, concentration was studied to optimize the experimental conditions. The number of electrons transferred was calculated and plausible oxidation mechanism was proposed. The ability of gold electrode to determine trace amount of MCP was studied using DPV. Limit of detection and quantification was calculated under the optimized conditions. For the analytical applications, pharmaceutical formulation and human urine sample analysis were performed. Various excipients were used to investigate their interference in the analytical application and it was found that the proposed method can be adopted for clinical trials, quality control and real sample analysis.

Using persistent homology to quantify a diurnal cycle in hurricanes

The diurnal cycle of tropical cyclones (TCs) is a daily cycle in clouds that appears in satellite images and may have implications for TC structure and intensity. The diurnal pattern can be seen in infrared (IR) satellite imagery as cyclical pulses in the cloud field that propagate radially outward from the center of nearly all Atlantic-basin TCs. These diurnal pulses, a distinguishing characteristic of this diurnal cycle, begin forming in the storm’s inner core near sunset each day, appearing as a region of cooling cloud-top temperatures. The area of cooling takes on a ring-like appearance as cloud-top warming occurs on its inside edge and the cooling moves away from the storm overnight, reaching several hundred kilometers from the circulation center by the following afternoon. The state-of-the-art TC diurnal cycle measurement in IR satellite imagery has a limited ability to analyze the behavior beyond qualitative observations. We present a method for quantifying the TC diurnal cycle using one-dimensional persistent homology, a tool from Topological Data Analysis, by tracking maximum persistence and quantifying the cycle using the discrete Fourier transform. Using Geostationary Operational Environmental Satellite IR imagery from Hurricanes Felix and Ivan, our method is able to detect an approximate daily cycle.

Caveolin proteins electrochemical oxidation and interaction with cholesterol

Caveolae consist in lipid raft domains composed of caveolin proteins, cholesterol, glycosphingolipids, and GPI-anchored proteins. Caveolin proteins present three different types, caveolin 1 (CAV-1), caveolin 2 (CAV-2) and caveolin 3 (CAV-3), with a very similar structure and amino acid composition. The native caveolin proteins oxidation mechanism was investigated for the first time, at a glassy carbon electrode, using cyclic, square wave and differential pulse voltammetry. The three native caveolin proteins oxidation mechanism presented only one tyrosine and tryptophan amino acid residues oxidation peak. Denatured caveolin proteins presented also the tyrosine, tryptophan and cysteine amino acid residues oxidation peaks. The reverse cholesterol transport is related to caveolae and caveolin proteins, and CAV-1 is directly connected to cholesterol transport. The influence of cholesterol on the three caveolin proteins electrochemical behaviour was evaluated. In the absence and in the presence of cholesterol, significant differences in the CAV-1 oxidation peak current were observed.

A screen-printed electrochemical sensing platform surface modified with nanostructured ytterbium oxide nanoplates facilitating the electroanalytical sensing of the analgesic drugs acetaminophen and tramadol.

An electrochemical sensing platform based upon screen-printing electrodes (SPEs) modified with nanostructured lanthanide metal oxides facilitate the detection of the widely misused drugs acetaminophen (ACP) and tramadol (TRA). Among the metal oxides examined, Yb2O3 nanoplates (NPs) were found to give rise to an optimal electrochemical response. The electroanalysis of ACP and TRA individually, and within mixtures, was performed using cyclic and differential pulse voltammetry. The ACP and TRA exhibited non-overlapping voltammetric signals at voltages of +0.30 and + 0.67V (vs. Ag/AgCl; pH9) using Yb2O3-SPEs. Pharmaceutical dosage forms and spiked human fluids were analyzed in wide linear concentration ranges of 0.25-654 and 0.50-115μmol.L-1 with limits of detection (LOD) of 55 and 87nmol.L-1 for ACP and TRA, respectively. The Yb2O3-SPEs offer a sensitive and chemically stable enzyme-free electrochemical platform for ACP and TRA assay. Graphical abstractSchematic presentation of one-shot electrochemical analysis of misused drugs, tramadol (TRA) and acetaminophen (ACP) by utilizing ytterbium oxide nanoplates modified screen-printed electrodes (Yb2O3-SPEs). The Yb2O3-SPEs showed interesting responses for ACP and TRA within pharmaceutical formulations and human fluids.

Distance Dependence of Electronic Coupling in Rigid, Cofacially Compressed, π-Stacked Organic Mixed-Valence Systems.

A series of new π-stacked compounds, 1,8-bis(2',5'-dimethoxybenzene-1'-yl)naphthalene (1), 1,4-bis(8'-(2″,5″-dimethoxybenzene-1″-yl)naphthalen-1'-yl)benzene (2), and 1,8-bis(4'-(8″-(2‴,5‴-dimethoxybenzene-1‴-yl)naphthalen-1″-yl)benzene-1'-yl)naphthalene (3), have been synthesized and characterized herein as precursor molecules of monocationic mixed-valence systems (MVSs). The three-dimensional geometries of these compounds were determined by X-ray crystallography. A near-orthogonal alignment of the naphthalene pillaring motif to the dimethoxybenzene redox center, or the phenylene spacer, imposes cofacial alignment of these units in a juxtaposed manner with sub-van der Waals interplanar distances. Cyclic and differential pulse voltammograms reveal that the ΔE values between two sequential oxidation potentials are 0.30, 0.11, and 0.10 V for 1, 2, and 3, respectively. MVSs derived from these compounds are recognized as class II according to the Robin and Day classification. The decay parameter β, which describes the distance dependence of the squared electronic coupling in the three mixed-valence systems, was experimentally determined via Mulliken-Hush analysis of the intervalence charge transfer band (β = 0.37 Å-1) and theoretically assessed from charge-resonance contributions derived from DFT computations (β = 0.37 Å-1). These values are extraordinarily mild, indicating that the electronic interaction between redox centers in the longitudinal direction may be comparable to that in the transverse direction, if the MVS system is appropriately designed.

Electrochemical quantification of pyridoxine (VB6) in human blood from other water-soluble vitamins

For the first time reporting a pencil graphite electrode modified with gold nanoparticles and non-conducting polymeric film of o-aminophenol for the selective determination of pyridoxine (VB6) from other water-soluble vitamins in human blood. The fabricated electrode was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, and attenuated total reflection infrared spectroscopy. Voltammetric response of VB6 on the fabricated electrode was investigated out using cyclic and differential pulse voltammetric techniques. Under optimized conditions, an irreversible oxidation peak at + 0.632 V was observed which corresponds to the oxidation of VB6. The oxidation peak current and the pyridoxine concentration were found to be linear in the range from 5 to 200 μM with a detection limit of 0.30 μM. The sensitivity of the proposed electrode was calculated to be 3.373 μA/μM/cm2 with excelled reproducibility and stability. The electrode is suitable for the routine analysis of VB6 in human blood samples as it highly selective from other water-soluble vitamins.

Highly efficient and selective quantification of vanillin in food, beverages and pharmaceuticals using surfactant modified carbon paste sensor

The rampant use of vanilla has severe ramifications on our health. Federal Office of Public Health has placed restrictions on use of Vanillin (VAN) in baby food. Our aim was to prepare a sensor for the swift determination of VAN in food essence, non-alcoholic beverages, food supplements and pharmaceutical formulations. A modified carbon paste electrode drop cast with cetyltrimethylammoniumbromide (CTAB) was designed and scrutinized by cyclic and differential pulse voltammetry techniques. Surface morphology was studied using Field emission scanning electron microscopy (FE-SEM), the elemental composition by Energy Dispersive X-rays (EDX), and charge transfer kinetics by Electrochemical Impedance Spectroscopy (EIS). A significant decline of 153 mV in anodic overpotential with an impressive eight-fold enhancement of current indicates better electrocatalytic kinetics at the modified electrode. The calibration curve exhibited linearity over a wide range of 8 × 10−8 to 3 × 10−3 M, with a limit of detection 0.23 nM (S/N = 3). The selectivity of the fabricated sensor towards VAN in the presence of 1000-fold excess of common interferants such as ferulic acid, folic acid, tryptophan, and uric acid was noteworthy.

Растворение железа и ионизация водорода в нейтральном боратном буфере при циклическом импульсе потенциала

Растворение железа и ионизация водорода в нейтральном боратном буфере при циклическом импульсе потенциала