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Biopolymer sodium alginate (SA) is actively used as a green membrane material. To improve the pervaporation properties of the SA membrane in the isopropanol dehydration, different water-soluble fullerene derivatives with L-amino acids (threonine, hydroxyproline, and arginine) were used. In this study, fullerene–arginine derivative (C60-Arg) was shown to be an optimal filler acting both as a modifier and a cross-linking agent for SA. Different cross-linking agents (phosphoric and citric acids, calcium chloride) were tested for dense membrane cross-linking to reinforce the membranes for the separation of diluted solutions. Two types of membranes based on SA and SA/C60-Arg (5%) were developed: dense and supported on polyacrylonitrile substrate. The structural features of obtained membranes were investigated by the following methods: FTIR spectroscopy, scanning electron (SEM), and atomic force (AFM) microscopies. The optimal transport properties in dehydration of isopropanol (12–100 wt.% water) were found for the cross-linked SA/C60-Arg (5%) membrane supported on PAN substrate. The following parameters were obtained: 0.5–4.7 kg/(m2h) permeation flux and constant 99.99 wt.% water content in the permeate.

Wide application of ultrafiltration in different industrial fields requires the development of new membranes with tailored properties and good antifouling stability. This study is devoted to the improvement of ultrafiltration properties of poly(m-phenylene isophtalamide) (PA) membranes by modification with titanium oxide (TiO2) particles. The introduction of TiO2 particles improved membrane separation performance and increased antifouling stability and cleaning ability under UV irradiation. The developed membranes were characterized by scanning electron and atomic force microscopy methods, the measurements of water contact angle, and total porosimetry. The transport properties of the PA and PA/TiO2 membranes were tested in ultrafiltration of industrially important feeds: coolant lubricant (cutting fluid) emulsion (5 wt.% in water) and bovine serum albumin (BSA) solution (0.5 wt.%). The PA/TiO2 (0.3 wt.%) membrane was found to possess optimal transport characteristics in ultrafiltration of coolant lubricant emulsion due to the highest pure water and coolant lubricant fluxes (1146 and 32 L/(m2 h), respectively), rejection coefficient (100%), and flux recovery ratio (84%). Furthermore, this membrane featured improved ability of surface contamination degradation after UV irradiation in prolonged ultrafiltration of BSA, demonstrating a high flux recovery ratio (89–94%).

The possibilities of laser-induced liquid phase chemical deposition (LCLD) of metal for continuous generation of nickel nanoparticles, the sizes of which allow their use as a catalyst for organic reactions are considered. The conditions for obtaining Ni nanoparticles by this method were optimized.

Electrochemical methods of analysis are usually characterized by high sensitivity, ease of automation, and a wide range of analytes and test samples. The development of electrochemical methods of analysis at the present stage is mostly determined by the creation of new nanostructured electrode materials with electrocatalytic properties. The use of such materials ensures an increase in the sensitivity and selectivity of the determination of a number of analytes. Another conventional way to decreasing the limit of detection for electrochemically active substances is the development of new measurement methods for improving the signal-to-noise ratio in nonequilibrium electrochemical methods of analysis. This article is devoted to the consideration of some new electrode materials and methods of electrochemical measurements.

Modern society strives for the development of sustainable processes that are aimed at meeting human needs while preserving the environment. Membrane technologies satisfy all the principles of sustainability due to their advantages, such as cost-effectiveness, environmental friendliness, absence of additional reagents and ease of use compared to traditional separation methods. In the present work, novel green membranes based on sodium alginate (SA) modified by a FeBTC metal–organic framework were developed for isopropanol dehydration using a membrane process, pervaporation. Two kinds of SA-FeBTC membranes were developed: (1) untreated membranes and (2) cross-linked membranes with citric acid or phosphoric acid. The structural and physicochemical properties of the developed SA-FeBTC membranes were studied by spectroscopic techniques (FTIR and NMR), microscopic methods (SEM and AFM), thermogravimetric analysis and swelling experiments. The transport properties of developed SA-FeBTC membranes were studied in the pervaporation of water–isopropanol mixtures. Based on membrane transport properties, 15 wt % FeBTC was demonstrated to be the optimal content of the modifier in the SA matrix for the membrane performance. A membrane based on SA modified by 15 wt % FeBTC and cross-linked with citric acid possessed optimal transport properties for the pervaporation of the water–isopropanol mixture (12–100 wt % water): 174–1584 g/(m2 h) permeation flux and 99.99 wt % water content in the permeate.

In this work, a reversed-phase dispersive liquid-liquid microextraction procedure based on the decomposition of deep eutectic solvent was suggested for the first time. The procedure was utilized for fast and simple separation of lead and cadmium from vegetable oil samples. The procedure assumed mixing of oil sample and DES based on menthol, formic acid and water. Water as component of DES promoted its decomposition in sample matrix resulting menthol dissolution in the sample phase and dispersion of aqueous formic acid solution. In this procedure menthol acted as a dispersive solvent during DES decomposition for dispersion of aqueous formic acid solution. The metals were determined by the square-wave anodic stripping voltammetry. The limits of detection, were 0.01 µg kg−1 for lead and 0.006 µg kg−1 for cadmium. The RSD was less then 6% for both analytes. The enrichment factor was 36 and 39 for lead and cadmium, respectively.

The aim of the study is to improve the performance of thin-film composite (TFC) membranes with a thin selective layer based on chitosan (CS) via different approaches by: (1) varying the concentration of the CS solution, (2) changing the porosity of substrates from polyacrylonitrile (PAN), (3) deposition of the additional ultrathin layers on the surface of the selective CS layer using interfacial polymerization and layer-by-layer assembly. The developed membranes were characterized by different methods of analyses (SEM and AFM, IR spectroscopy, measuring of water contact angles and porosity). The transport characteristics of the developed TFC membranes were studied in pervaporation separation of isopropanol/water mixtures. It was found that the application of the most porous PAN-4 substrate with combination of formation of an additional polyamide selective layer by interfacial polymerization on the surface of a dense selective CS layer with the subsequent layer-by-layer deposition of five bilayers of poly (sodium 4-styrenesulfonate)/CS polyelectrolyte pair led to the significant improvement of permeance and high selectivity for the entire concentration feed range. Thus, for TFC membrane on the PAN-4 substrate the optimal transport characteristics in pervaporation dehydration of isopropanol (12&ndash, 90 wt.% water) were achieved: 0.22&ndash, 1.30 kg/(m2h), 99.9 wt.% water in the permeate.

A novel method for one-step preparation of antifouling ultrafiltration membranes via a non-solvent induced phase separation (NIPS) technique is proposed. It involves using aqueous 0.05&ndash, 0.3 wt.% solutions of cationic polyelectrolyte based on a copolymer of acrylamide and 2-acryloxyethyltrimethylammonium chloride (Praestol 859) as a coagulant in NIPS. A systematic study of the effect of the cationic polyelectrolyte addition to the coagulant on the structure, performance and antifouling stability of polysulfone membranes was carried out. The methods for membrane characterization involved scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), contact angle and zeta-potential measurements and evaluation of the permeability, rejection and antifouling performance in human serum albumin solution and surface water ultrafiltration. It was revealed that in the presence of cationic polyelectrolyte in the coagulation bath, its concentration has a major influence on the rate of &ldquo, solvent&ndash, non-solvent&rdquo, exchange and thus also on the rate of phase separation which significantly affects membrane structure. The immobilization of cationic polyelectrolyte macromolecules into the selective layer was confirmed by FTIR spectroscopy. It was revealed that polyelectrolyte macromolecules predominately immobilize on the surface of the selective layer and not on the bottom layer. Membrane modification was found to improve the hydrophilicity of the selective layer, to increase surface roughness and to change zeta-potential which yields the substantial improvement of membrane antifouling stability toward natural organic matter and human serum albumin.

Novel mixed-matrix membranes based on polyvinyl alcohol and its composites with carboxyfullerene were developed. Carboxyfullerene was simultaneously used as a modifier and a cross-linker for polyvinyl alcohol. The structural properties of the developed composites were studied by nuclear magnetic resonance, X-ray diffraction analysis, scanning electron microscopy, and sorption experiments. Thermal properties and stability were investigated by thermogravimetric analysis and differential scanning calorimetry. Surface features were studied by measuring the contact angles by water. The transport properties of the developed membranes were studied in ethanol-water mixtures separation by pervaporation (4.4–90 wt.% water in the feed) at different temperatures (22, 35, 50 °C). All membranes were selective with respect to water. The optimal transport properties were obtained for the PVA-carboxyfullerene (3.5 wt.%) membranes containing catalyst p-toluenesulfonic acid.

The paper describes the results of using Raman spectroscopy to study the canvases of Russian avant-garde artists. The study aimed to identify stable signs of paints for the recognition of counterfeits. The subject of the research was zinc white as a component of paints used by the 20th-century Russian avant-garde. Temporal changes occurring with them are due to chemical reactions of organic paint components with whites and with each other. The study shows that Raman spectroscopy is the most sensitive method for detecting ZnO time markers. Its results are compared with the results of pyrolysis–gas chromatography, mass spectrometry, and X-ray analysis of paints from paintings from the Russian avant-garde of the early, middle, and late twentieth century. The study results demonstrate that the paint compositions of the early and late 20th Century have significant similarities. The result of their aging is the appearance of products of thermal desorption and pyrolysis in the form of a homologous series of alcohols and aromatic hydrocarbons formed during the destruction and oxidation of oleic, linoleic, linolenic, palmitic, stearic acids, and/or azelaic acid. These acids are found in flaxseed oil. Zinc white of the early 20th century contains significant additions of gypsum. The composition of the components of mid-century paints is much less diverse. Genuine paintings contain homologous series of fatty acids sorbed on zinc oxide. The paper analyzes historical reasons for this phenomenon. The research shows that one of the stable signs of falsification is the use of titanium white and organic catalysis products based on them. The results of gas chromatography and mass spectrometry and Raman spectroscopy are supplemented by X-ray phase and X-ray fluorescence analysis. The paper provides detailed reference data on the spectra of Raman light scattering, thermal desorption, and pyrolysis of paints of the studied canvases and shows the differences in the mass spectra of genuine paintings and falsifications.

This study focuses on the development of a green pervaporation (PV) process for dehydrating a wide range of commercially significant mixtures such as concentrated (and corrosive) acetic acid blends using mixed-matrix membranes based on polyvinyl alcohol (PVA) cross-linked by low-hydroxylated fullerenol (C 60 (OH) 12 ). The effect of C 60 (OH) 12 and various conditions of physical cross-linking on the structure and internal morphology of composite membranes was investigated by X-ray diffraction and scanning electron microscopy, and the stability and transport properties of the developed membranes were investigated for acetic acid dehydration at a wide range of feed water contents (5–30 wt.%) and temperatures (25–60 °C). The supported mixed-matrix membranes exhibited high permeances and water selectivities, as well as good stability toward feed mixtures, with the best transport properties obtained for a C 60 (OH) 12 (5 wt.%)-PVA supported composite membrane thermally treated at 140 °C for 420 min.

Interrupted amperometry is a new highly sensitive method for diffusion current measuring. The main feature of the proposed technique is the use of capacitive current as the analytical signal together with the faradaic current. The conventional electrical circuit for amperometric measurements is complemented by a switcher that enables periodical interruption of the circuit. The technique was successfully applied for direct amperometric determination of lead, cadmium and iron ions, phenol and hydroquinone; for determination of dichromate ion via titration; for determination of dissolved oxygen in water by Clark-type sensor. In all the mentioned cases the achieved values of analytical characteristics are significantly better than for conventional amperometric methods. There are limitations and perspectives of the proposed technique considered.

This study focuses first on the preparation of mixed matrix supported membranes of polyvinyl alcohol (PVA) and low-hydroxylated fullerenol C60(OH)12 used to create water selective membranes and then on their pervaporation properties for the separation of water-THF mixtures. These novel supported PVA membranes containing nano-carbon particles were prepared to reach high membrane performance for further integration in a dehydration process, such as distillation coupled to pervaporation. The separation of water-THF mixtures was performed with the supported membranes over a wide range of water concentrations in the feed mixture, i.e., from the azeotrope range up to 30 wt%, to evaluate the performance and stability of the thin active layer. SEM was used to visualize the internal morphology of the membrane. The influence of temperature on the transport properties was also investigated. All the membranes were highly water selective and stable up to 30 wt% water in the feed. The best compromise of transport properties was obtained for the C60(OH)12(5%)-PVA supported composite membrane: a permeate enrichment of 99.3 ± 0.3 wt% water and a flux of 0.25 ± 0.02 kg/(m2 h) for the separation of a mixture containing 5.7 wt% water and 94.3 wt% tetrahydrofuran (THF) at 30 °C. Considering its water stability, this supported membrane with a dense layer thinner than 2 μm appears promising for use in hybrid industrial processes to upgrade solvents with a smaller environmental footprint than conventional methods.

The analytical characteristics of gold nanowires prepared by direct electrochemical synthesis were studied with the use of the amperometric determination of glucose as an example. The applicability of the gold nanowires to the determination of glucose in a neutral medium (a phosphate buffer solution with pH 7.2) over a concentration range from 1 × 10–4 to 5 × 10–3 M at a detection potential of +0.35 V was shown. It was found that the sensitivity of a nonenzymatic sensor for the determination of glucose on the gold nanowires was high: 3.7 × 10–4 A M–1 m–2. The limit of detection was 3.3 × 10–5 M.

In this work, dense and supported pervaporation polyvinyl alcohol (PVA)-based membranes modified with poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate)(PSS)/PAH top nanolayers were synthesized. Two main points were investigated: the role of the polyelectrolyte PAH on water selectivity of the selective polymer matrix and the impact of the porous substrate based on polyacrylonitrile (PAN) and aromatic polysulfone amide (UPM-20&reg, ), used to get supported high-performance membranes. Various methods of analysis (fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), porosity, contact angles, ultrafiltration) were applied to study the developed membranes. Transport characteristics of the developed membranes were studied in isopropanol dehydration by pervaporation. Obtained results are discussed in the light of the structure and physicochemical characteristics of these PVA/PAH membranes and the types of porous substrate. It was shown that the PAN-supported membrane with the selective layer based on PVA/PAH modified by 10 polyelectrolyte PSS/PAH bilayers possessed ~4.5 times higher permeation flux with the same high selectivity level (99.9 wt % water in the permeate) for the dehydration of the isopropanol (20 wt % water) at 60 &deg, C compared to the commercial analog PERVAPTM 1201.

The year 2019 marks the 150th year of the founding of analytical chemistry department at St. Petersburg State University and of the founding of the periodic table of chemical elements as proposed by Professor Dmitry Mendeleev. 2019 has been decreed by chemists as the “International Year of the Periodic Table” in celebration of these historical events. A celebration marking this anniversary was held at the university on March 1. This historical account will recount the early days of the department and Mendeleev's development of the periodic table, and then highlight some of the major analytical contributions of the department.

Microfluidics-based biochips for biochemical analysis are receiving much attention nowadays. These composite microsystems, also known as lab-on-a-chip or bio-MEMS, offer a number of advantages over conventional laboratory procedures. They automate highly repetitive laboratory tasks by replacing cumbersome equipment with miniaturized and integrated systems, and they enable the handling of small amounts, e.g., micro- and nano-liters, of fluids. Thus they are able to provide ultra-sensitive detection at significantly lower costs per assay than traditional methods, and in a significantly smaller amount of laboratory space. Advances in microfluidics technology offer exciting possibilities in the realm of enzymatic analysis (e.g., glucose and lactate assays), DNA analysis (e.g., PCR and nucleic acid sequence analysis), proteomic analysis involving proteins and peptides, immuno-assays, and toxicity monitoring. Biochips can be used to detect molecules and/or sequence nucleic acid molecules with aid of an array of electrochemical detector cells containing one or more electrodes per cell where each cell being electrically isolated at a wafer level. For many applications it is beneficial to form a non-planar working electrode using a metal which will corrode during CMP steps. We’ve developed a novel Ag and Cu integration process which a) solves problems of metal corrosion over 3D topography during CMP step and b) prevents metal surface contamination with CMP residual slurry and polishing byproducts not usually removable by brush or megasonic cleaning. Electrochemical studies show corrosion behavior of thick Ag layers in different CMP slurries used in this process. SEM images of cross-sectioned metal lined electrochemical cells (vias) clearly demonstrate advantages of new process (right) without traces of corrosion vs conventional CMP process (left). This process can be used also for polishing of other metals and dielectrics over topography where aggressive cleaning post-CMP steps are not desirable. Figure 1

As a rule, the polymeric membranes have low permeability in separation of low molecular weight components. In spite of this fact, the membrane processes have significant advantages compare with conventional technologies, in particular, low energy consumption and environmental friendliness. To improve transport properties of the polymer membrane their modification should be carried out. In the present work, the development of highly methanol-permeable pervaporation membranes based on poly-m-phenylene isophthalamide (PA) is achieved by two strategies: (i) modification of PA by novel synthesized and characterized highly stable metal–organic framework UiO-66(NH2)-EDTA particles and (ii) development of supported membranes with thin selective layer on the regenerated cellulose substrate. First time the composite structure has been simulated: atomistic molecular dynamics simulations demonstrate the partial penetration of polymer inside the modifier and confirms the nature of the interaction between polymer and modifier assessed by spectroscopic methods. The optimal characteristics in respect of industrial use are obtained for supported PA/UiO-66(NH2)-EDTA (15%) membrane: 1.55 kg/(m2h) permeation flux and 93.1 wt% methanol in the permeate for the separation of azeotropic methanol/toluene mixture.

Novel dense and supported (polyacrylonitrile substrate) mixed matrix membranes based on biopolymer sodium alginate (SA), modified by Zr-MOFs were developed to improve pervaporation dehydration properties of a parent SA membrane. The following Zr-MOFs were synthesized and tested as modifiers: unmodified UiO-66 and modified UiO-66(NH2)-AcOH and UiO-66(NH2)-EDTA. Two kinds of mixed matrix membranes were developed: without additional treatment and cross-linked with calcium chloride. The synthesized Zr-MOFs nanoparticles and developed SA and SA-Zr-MOFs membranes were studied using Fourier-transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, surface area measurement, atomic force microscopy, X-ray diffraction analysis, thermogravimetric analysis, and swelling experiments. Dense and supported membranes were tested for their transport properties in the pervaporation dehydration of isopropanol (12, 30 wt% water for the untreated membranes and 12–100 wt% water for the cross-linked membranes). The best transport properties (dehydration of water/isopropanol mixtures at 22 °C) were demonstrated by a supported cross-linked membrane, containing 15 wt% of UiO-66: permeation flux 0.47–3.38 kg/(m2h), water content in permeate 99.9-97.5 wt%.

Membrane methods, especially pervaporation, are quickly growing up. In line with that, effective membrane materials based on biopolymers are required for the industrially significant mixtures separation. To essentially improve membrane transport characteristics, the application of the surface or/and bulk modifications can be carried out. In the present study, novel dense and supported membranes based on hydroxyethyl cellulose (HEC)/sodium alginate (SA) were developed for pervaporation dehydration of isopropanol using several approaches: (1) the selection of the optimal ratio of polymers, (2) the introduction of fullerenol in blend polymer matrix, (3) the selection of the optimal cross-linking agent for the membranes, (4) the application of layer-by-layer deposition of polyelectrolytes on supported membrane surface (poly(sodium 4-styrenesulfonate) (PSS)/poly(allylamine hydrochloride) (PAH) and PSS/SA). Structural and physicochemical characteristics of the membranes were analyzed by different methods. A cross-linked supported membrane based on HEC/SA/fullerenol (5%) composite possessed the following transport characteristics in pervaporation dehydration of isopropanol (12–50 wt.% water): 0.42–1.72 kg/(m2h) permeation flux, and 77.8–99.99 wt.% water content in the permeate. The surface modification of this membrane with 5 bilayers of PSS/PAH and PSS/SA resulted in the increase of permeation flux up to 0.47–3.0 and 0.46–1.9 kg/(m2h), respectively, with lower selectivity.

The new method, interrupted amperometry, is proposed to increase the sensitivity of amperometric measurements. Analytical possibilities of interrupted amperometry on solid electrodes are studied on an example of the determination of phenolic compounds in aqueous solutions.

Ranges of neodymium reduction potentials in aqueous solutions of potassium chloride at pH = 2 and in solutions containing glycine were determined by differential pulse polarography. The glycine complex with neodymium is not formed in the range of the amino acid concentration 0.001–0.12 M. Glycine adsorption on a mercury electrode and on an electrode modified with neodymium was studied by the cyclic voltammetry method.

This work focuses on the incorporation of fullerenol nanoparticles to get PVA-fullerenol mixed matrix membranes for alcohol dehydration by pervaporation. Cross-linked hybrid membranes based on composites of polyvinyl alcohol (PVA) and low-hydroxylated fullerenol C60(OH)12 have been prepared by two different procedures. To improve the dispersion of the functionalized fullerene in the PVA network, the hydrodynamic properties of PVA, fullerenol and PVA/fullerenol composites in dilute solutions were studied by viscometry and dynamic light scattering. It was shown that the aggregate sizes increased with the increase of fullerenol content in the PVA/fullerenol composite solutions. The effect of low-hydroxylated fullerenol on the structure and morphology of PVA membranes was investigated by small-angle X-ray scattering and atomic force microscopy. It was observed that the incorporation of 5 wt.% fullerenol and cross-linking with maleic acid led to a more uniform distribution of the amorphous PVA phase. As a result, membrane transport characteristics were improved for the dehydration of n-butanol–water mixtures by pervaporation. The PVA membranes containing 35 wt.% maleic acid and 5 wt.% fullerenol exhibited the best transport properties. Keywords: Polyvinyl alcohol, Fullerenol, Composite, n-Butanol, Pervaporation

A novel vapor permeation-stepwise injection (VP-SWI) method for the determination of methanol and ethanol in biodiesel samples is discussed. In the current study, stepwise injection analysis was successfully combined with voltammetric detection and vapor permeation. This method is based on the separation of methanol and ethanol from a sample using a vapor permeation module (VPM) with a selective polymer membrane based on poly(phenylene isophtalamide) (PA) containing high amounts of a residual solvent. After the evaporation into the headspace of the VPM, methanol and ethanol were transported, by gas bubbling, through a PA membrane to a mixing chamber equipped with a voltammetric detector. Ethanol was selectively detected at +0.19 V, and both compounds were detected at +1.20 V. Current subtractions (using a correction factor) were used for the selective determination of methanol. A linear range between 0.05 and 0.5% (m/m) was established for each analyte. The limits of detection were estimated at 0.02% (m/m) for ethanol and methanol. The sample throughput was 5 samples h(-1). The method was successfully applied to the analysis of biodiesel samples.

One of the key aims of electroanalytical methods development is the increase in sensitivity of measurements. This communication reports about a new amperometric technique called “interrupted amperometry” that is based on periodic interruption of the measuring electrical circuit. The main feature of this method is that capacitive current is analytically useful as well as faradaic current. This enables a dramatically higher sensitivity compared to the conventional amperometry. Theoretical consideration of the proposed method as well as the design of the home-made instrumentation is presented. Iron (III) was chosen as a model analyte in this preliminary study in order to demonstrate analytical possibilities of interrupted amperometry. The theoretical limit of detection of iron (III) at a carbon rotating disk electrode was found to be 3 nM. The calibration curve is linear in the whole investigated concentration range from 0.02 to 0.38 μM and gave a value of 1.22 μA μM −1 for the sensitivity. These results were compared with the values obtained in conventional direct-current amperometry mode other conditions being the same: 0.2 μM and 0.81 nA μM −1 for the limit of detection and sensitivity, respectively. The proposed technique can be useful for titration, flow injection analysis, HPLC, amperometric sensors, potentiostatic coulometry and for amperometric measurements with ultramicroelectrodes.

The aim of this paper is testing a computer game as an alternative tool for the assessment of intelligence and creativity of school children. The relevance of the research task is determined by the growing interest in practical psychology in the use of computer games as a special diagnostic tool in educational process. There are two original factor models that have been developed and the structural equation modeling of measured parameters has been carried out. The relationships between game dynamic and final individual results in the computer game, on the one hand, and psychometric intelligence and divergent creativity, on the other, are presented. Weak correlation between the above-mentioned and individually measured intellectual and creativity characteristics of the participants with the computer game results was discovered. Consideration of these characteristics in the form of a common latent factor makes it possible to identify the corresponding dependencies only in some cases when there is a dividing the sample into groups according to their ability level. Particularly, the dynamics of game scoring allows to refer participants to the target group with a certain level of abilities (high intelligence and creativity versus low intelligence and creativity), and it is the high level of psychological traits that determines effectiveness in the game behavior, but not vice versa. The qualitative ratios of the two groups of subsets of participants were revealed: weak, medium and strong players and players with three different levels of psychological abilities. The prospects for the further use of computer games for assessment of cognitive abilities in the measurement of combination of psychological abilities are discussed.

Novel mixed matrix dense and supported membranes based on biopolymer sodium alginate (SA) modified by fullerenol were developed. Two kinds of SA&ndash, fullerenol membranes were investigated: untreated and cross-linked by immersing the dry membranes in 1.25 wt % calcium chloride (CaCl2) in water for 10 min. The structural and physicochemical characteristics features of the SA&ndash, fullerenol composite were investigated by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic methods, scanning electron (SEM) and atomic force (AFM) microscopies, thermogravimetric analysis (TGA), and swelling experiments. Transport properties were evaluated in pervaporation dehydration of isopropanol in a wide concentration range. It was found that the developed supported cross-linked SA-5/PANCaCl2 membrane (modified by 5 wt % fullerenol) possessed the best transport properties (the highest permeation fluxes 0.64&ndash, 2.9 kg/(m2 h) and separation factors 26&ndash, 73,326) for the pervaporation separation of the water&ndash, isopropanol mixture in the wide concentration range (12&ndash, 90 wt % water) at 22 &deg, C and is suitable for the promising application in industry.

We report one-step in situ laser-induced synthesis of the conductive copper microstructures doped with iron, zinc, nickel, and cobalt with highly developed surface area. It was observed that the presence of chlorides of the aforementioned metals in the solutions used in our experiments increases the deposition rate and the amount of copper in the resulting deposits; it also leads to the deposit miniaturization. The laser deposition from solutions containing cobalt (II) chloride of concentration more than 0.003 M results in fabrication of copper microelectrode with better electrochemical properties than those deposited from solutions containing chlorides of other metals of the same concentration. Moreover, copper microelectrode doped with cobalt has demonstrated good reproducibility and long-run stability as well as sensitivity and selectivity towards determination of hydrogen peroxide (limit of detection-0.2 μM) and d -glucose (limit of detection-2.2 μM). Thus, in this article we have shown the opportunity to manufacture two-phase microcomposite materials with good electrical conductivity and electrochemical characteristics using in situ laser-induced metal deposition technique. These materials might be quite useful in development of new perspective sensors for non-enzymatic detection of such important analytes as hydrogen peroxide and glucose.

In the present work, the novel dense and supported membranes based on polyvinyl alcohol (PVA) with improved transport properties were developed by bulk and surface modifications. Bulk modification included the blending of PVA with chitosan (CS) and the creation of a mixed-matrix membrane by introduction of fullerenol. This significantly altered the internal structure of PVA membrane, which led to an increase in permeability with high selectivity to water. Surface modification of the developed modified dense membranes, based on composites PVA-CS and PVA-fullerenol-CS, was performed through (i) making of a supported membrane with a thin selective composite layer and (ii) applying of the layer-by-layer assembly (LbL) method for coating of nano-sized polyelectrolyte (PEL) layers to increase the membrane productivity. The nature of polyelectrolyte type—(poly(allylamine hydrochloride) (PAH), poly(sodium 4-styrenesulfonate) (PSS), poly(acrylic acid) (PAA), CS), and number of PEL bilayers (2–10)—were studied. The structure of the composite membranes was investigated by FTIR, X-ray diffraction, and SEM. Transport properties were studied during the pervaporation separation of 80% isopropanol–20% water mixture. It was shown that supported membrane consisting of hybrid layer of PVA-fullerenol (5%)–chitosan (20%) with five polyelectrolyte bilayers (PSS, CS) deposited on it had the best transport properties.

The present study of nanoelectrochemical sensors prepared by directed electrochemical nanowire assembly (DENA) is defined by the requirements of electrochemical analysis, where the transducer function of metallic nanowires is synergetically combined with their electrochemical catalytic activity with respect to a particular analyte. We show for the first time that this technique can be employed for metals (Pd, Au) and their bimetallic compositions to create various multicomponent sensor nanomaterials on a single chip without the use of multistep lithography for the spatially resolved analysis of solutions. The nanostructures of various compositions can be individually addressed when used in liquid media, so that the particular surface properties of the individual nanoarray elements can be used for the electrochemical analysis of specific analytes. The sensor application of these devices in electrolytes and cell culture conditions has been demonstrated for the first time. As an example, the Pd-Au nanowires prepared by DENA were used for a non-enzymatic analysis of H2O2 with a linear concentration interval of 10−6–10−3 M, sensitivity of 18 μA M−1, and detection limit of 3 × 10−7 M at as low absolute value of the detection potential as − 0.05 V. This sensor was also proven for the detection of hydrogen peroxide in HL-1 cell culture, demonstrating good biocompatibility and support for the cell culture conditions. Using various DENA-grown electrochemical compositions on a single chip, a novel multisensor platform is proposed for the determination of various analytes in electrolyte solutions for biocompatible sensor arrays, flexible multianalyte environmental and technological process monitoring, and healthcare areas.

An easily performed miniaturized, cheap, selective and sensitive procedure for the determination of H2S in fuel oil samples based on a headspace liquid-phase microextraction followed by a cyclic voltammetry detection using a paper-based analytical device (PAD) was developed. A modified wax dipping method was applied to fabricate the PAD. The PAD included hydrophobic zones of sample and supporting electrolyte connecting by hydrophilic channel. The zones of sample and supporting electrolyte were connected with nickel working, platinum auxiliary and Ag/AgCl reference electrodes. The analytical procedure included separation of H2S from fuel oil sample based on the headspace liquid-phase microextraction in alkaline solution. Then, sulfide ions solution obtained and supporting electrolyte were dropped on the zones followed by analyte detection at + 0.45 V. Under the optimized conditions, H2S concentration in the range from 2 to 20 mg kg−1 had a good linear relation with the peak current. The limit of detection (3σ) was 0.6 mg kg−1. The procedure was successfully applied to the analysis of fuel oil samples.

A coulometric procedure was suggested for determining the concentration of dissolved oxygen in water. The procedure can be used for automation of measurements at nuclear and thermal power plants. The sensor design was developed for experimental check of the procedure, and operation parameters of the sensor were found. The concentrations calculated from the results of coulometric measurements are in good agreement with those found amperometrically with the classical Clark sensor.

This study focuses first on the preparation of mixed matrix supported membranes of polyvinyl alcohol (PVA) and low-hydroxylated fullerenol C

The continuous in situ laser-induced catalysis proceeding via generation and growth of nano-sized copper particles was discussed. Also, the simple and lost-cost method for manufacturing of microstructural copper electrodes was proposed. The electrochemical properties of these electrodes were studied by cyclic voltammetry and impedance spectroscopy. The surface of the deposited copper structures (electrodes) was investigated by X-ray photoelectron spectroscopy and atomic force microscopy. These microstructures are highly conductive and porous with a dispersion of pore size ranging from 50 nm to 50 μm. An analytical response of the fabricated copper electrode is 30 times higher than those observed for a pure bulk copper with similar geometric parameters. A study of sensory characteristics for hydrogen peroxide determination showed that the value of Faraday current at the fabricated copper electrode is 2-2.5 orders of magnitude higher than for etalon one.

The simple and cheap method for fabrication of micro-sized electrochemical electrodes was proposed. The porous copper microstructures synthesized by laser-induced metal deposition technique were used as an indicator electrode, whereas a bulk polycrystalline copper with similar geometric parameters was used as an etalon electrode. The electrochemical properties of these electrodes were studied by cyclic voltammetry and impedance spectroscopy. The surface of the deposited copper structures was investigated by X-ray photoelectron spectroscopy and atomic force microscopy. An analytical response of the fabricated copper electrode is 15 times higher than those observed for a pure bulk copper. A study of sensory characteristics for hydrogen peroxide and d-glucose detection showed that the value of Faraday current at the fabricated copper electrode is 2–2.5 orders of magnitude higher than for etalon one.

The synthesis of conductive gold and copper-gold microstructures with high developed surface based on the method of laser-induced metal deposition from solution was developed. The topology and crystallization phase of these structures were observed by means of scanning electron microscopy and X-ray diffraction, respectively. The electrochemical properties of the synthesized materials were investigated using cyclic voltamperometry and amperometry. According to the obtained results, it was found out that copper-gold microstructures demonstrate a linear dependence of Faraday current vs. concentration from 0.025 to 5µM for D-glucose and from 0.025 to 10µM for hydrogen peroxide. In turn, gold deposit exhibits a linear dependence of Faraday current vs. concentration from 0.025 to 50µM for D-glucose and from 0.025 to 1µM for hydrogen peroxide. Moreover, the synthesized materials reveal low detection limits (0.025µM) with respect to the aforementioned analytes, which is quite promising for their potential application in design and fabrication of new non-enzymatic biosensors.

The influence of cobalt (II) chloride on laser-induced copper deposition was studied. Copper deposition experiments in aqueous solutions containing various concentrations of cobalt (II) chloride upon 532 laser irradiation were performed. The influence of additives on the deposition rate, the topology, electrochemical properties of the deposited microstructures was investigated. Sensory activity of these structures towards hydrogen peroxide and glucose was studied.

The method of laser-induced metal deposition was applied to synthesize nano- and microstructured metal electrodes for non-enzymatic glucose and hydrogen peroxide sensing. These electrodes were characterized by SEM, EDX, SIMS, XRD and EIS. Copper electrodes have a linear dependence of the current-concentration in the range of 10–100 μmol/L for hydrogen peroxide and 0.6–3.0 mmol/L for D-glucose.

The new possibilities of stripping coulometry method (SCM) using coulometric constant for the determination of the total electric charge are addressed. Since SCM is a method critical to the volume of the sample solution, the use of screen-printed electrodes (SPE) can significantly reduce the time of measurement. This work is devoted to the development of the new ways to define the coulometric constants and SCM determination of Pb and Hg at SPE.

Electrochemical method for arsenic determination at concentrations characteristic of inversion voltammetry was suggested. The method does not require calibration of the measuring instrument against standard solutions or application of the standard-additive technique. The method of no-reference inversion-volammetric determination is based on calculating the arsenic concentration in solution with the use of the preliminarily determined coulometric constant of an electrochemical cell.

Possibility of no-reference inversion-voltammetric determination of lead in aqueous solutions with the use of a preliminarily determined coulometric constant of the electrochemical cell, which enables substantially faster analysis as compared with the known analogs, was studied. The coulometric constants of electrochemical cells with a mercury film electrode were found for different solution volumes.

It was shown that mercury(II) in aqueous solutions can be determined by standardless stripping voltammetry based on the determination of the coulometric constant of the electrochemical cell. This approach considerably reduces the analysis time in comparison to the known analogs. The coulometric constants were found for electrochemical cells with a gold and a gold-graphite film electrodes in solutions of different volumes. The optimum time of preelectrolysis was determined for measurements using the proposed method.

A standardless electrochemical method for metal ion determination in aqueous solution is proposed. This method is based on the combination of stripping voltammetry and controlled potential coulometry laws. Its application requires neither calibration using standard solutions nor standard additions to the studying solutions. The efficiency of the new method was examined using the detection of mercury, cadmium, copper and lead ions in aqueous media. The interference of metal ions was studied, and the determination of each metal ion was carried out in the presence of the others. The method was tested on samples of river water analyzed independently by atomic absorption spectrometry. A good agreement of the results was demonstrated.