The rational design of composites based on graphene/metal oxides is one of the pillars for advancing their application in various practical fields, particularly gas sensing. In this study, a uniform distribution of ZnO nanoparticles (NPs) through the graphene layer was achieved, taking advantage of amine functionalization. The beneficial effect of amine groups on the arrangement of ZnO NPs and the efficiency of their immobilization was revealed by core-level spectroscopy, pointing out strong ionic bonding between the aminated graphene (AmG) and ZnO. The stability of the resulting Am-ZnO nanocomposite was confirmed by demonstrating that its morphology remains unchanged even after prolonged heating up to 350 °C, as observed by electron microscopy. On-chip multisensor arrays composed of both AmG and Am-ZnO were fabricated and thoroughly tested, showing almost tenfold enhancement of the chemiresistive response upon decorating the AmG layer with ZnO nanoparticles, due to the formation of p-n heterojunctions. Operating at room temperature, the fabricated multisensor chips exhibited high robustness and a detection limit of 3.6 ppm and 5.1 ppm for ammonia and ethanol, respectively. Precise identification of the studied analytes was achieved by employing the pattern recognition technique based on linear discriminant analysis to process the acquired multisensor response.

A new method of using the detonation nanodiamond with positive and negative zeta potential as a spacer for aerogels based on graphene oxide is presented. It is shown that the dosed addition of detonation nanodiamonds' particles to the suspension of graphene oxide hydrosol made it possible to triple the specific surface area of the resulting aerogel compared to graphene oxide aerogel, and this effect is more significant when nanodiamonds with a positive zeta potential are used. It was also shown that aerogels derived from graphene oxide and detonation nanodiamond with a positive zeta potential have a specific morphology with graphene oxide platelets being twisted. This effect is discussed in terms of the change in the average zeta potential of the initial mixtures. Keywords: two-component systems, carbon materials, colloid chemistry.

The results of measurements of the frequency dependence of the active resistance of a circular cross-section of aluminum and copper conductors with a various diameter in a wide frequency range from 20 Hz to 2 MHz are presented. Using the skin effect simulation we show that for all types of wires an increased active resistance observed, compared to the theoretical values in the frequency range above 200 kHz, where the skin layer thickness becomes less than 200 μm. This phenomenon may be associated with the manufacturing process of a metal wire by drawing through a die, when defects are formed in the near-surface layer, leading to its increased resistivity.

A set of GaAs whisker crystallites in the shape of hexagonal prism with the axisalong the [111] direction have been modeled as well as constructions consisting of such prisms. For these model samples XRD patterns have been calculated. Basing on the calculated XRD pattern analysis, a fitting configuration of prismatic fragments has been built for an atomic array obtained with the help of applying molecular dynamics techniques to the initial model prismatic GaAs crystallite. Keywords: whiskers, XRD pattern simulation, A III B V semiconductors, gallium arsenide.

An important role in satisfying the high quality of life of the population and modern industry is played by the reliability of power supply and ensuring uninterrupted delivery of electricity. As a result of a large number of emergency failures of elements caused by external factors, information about the technical state of elements in real time is not used by dispatching centers. These conditions cause difficulties in assessing the reliability of power lines and timely elimination of developing defects, which cause high transmission losses and lead to wire breaks and failures. Considering a digital photo or other raster image to assess the surface of power lines wires, we know that it is an array of numbers recorded by sensors of brightness levels, in a two-dimensional plane. Knowing that in mathematical terms a thin lens performs the Fourier transform of images placed in the focal planes, it is possible to create image processing algorithms, which are analogues of image processing by a classical optical system. An algorithm for automatic processing of scanning electron microscopy images aimed at detecting and describing surface defects in power line wires is proposed, which is implemented in the Python programming language. The algorithm proposes to use a Fourier transform procedure to eliminate the image brightness gradient and suppress high-frequency noise in the image by applying a two-dimensional bandpass filter. The necessity and parameters of the dynamic range normalization of the filtered image are determined. The binarization parameters of the normalized image are determined. A quantitative assessment of the degree of defectiveness of the investigated wire surface has been proposed. A quantitative assessment of the degree of elongation of defects on the surface of the investigated wire has been proposed.

Absorbed power of the neutral-injection beam in spherical tokamaks Globus-M/M2 is estimated numerically. Deceleration of fast particles is simulated by means of the NUBEAM code. The signal of analyzer of charge-exchange atoms is simulated by means of the FIDASIM code using the distribution function of fast ions calculated by means of the NUBEAM code. Comparison of calculated and experimental signals allowed determining the degree of influence of instabilities on confinement of fast particles along with absorbed beam power.

The artificial olfaction units (or e-noses) capable of room-temperature operation are highly demanded to meet the requests of society in numerous vital applications and developing Internet-of-Things. Derivatized 2D crystals are considered as sensing elements of choice in this regard, unlocking the potential of the advanced e-nose technologies limited by the current semiconductor technologies. Herein, we consider fabrication and gas-sensing properties of On-chip multisensor arrays based on a hole-matrixed carbonylated (C-ny) graphene film with a gradually changed thickness and concentration of ketone groups of up to 12.5 at.%. The enhanced chemiresistive response of C-ny graphene toward methanol and ethanol, of hundred ppm concentration when mixing with air to match permissible exposure OSHA limits, at room-temperature operation is signified. Following thorough characterization via core-level techniques and density functional theory, the predominant role of the C-ny graphene-perforated structure and abundance of ketone groups in advancing the chemiresistive effect is established. Advancing practice applications, selective discrimination of the studied alcohols is approached by linear discriminant analysis employing a multisensor array's vector signal, and the fabricated chip's long-term performance is shown.

The derivatization of graphene to engineer its band structure is a subject of significant attention nowadays, extending the frames of graphene material applications in the fields of catalysis, sensing, and energy harvesting. Yet, the accurate identification of a certain group and its effect on graphene’s electronic structure is an intricate question. Herein, we propose the advanced fingerprinting of the epoxide and hydroxyl groups on the graphene layers via core-level methods and reveal the modification of their valence band (VB) upon the introduction of these oxygen functionalities. The distinctive contribution of epoxide and hydroxyl groups to the C 1s X-ray photoelectron spectra was indicated experimentally, allowing the quantitative characterization of each group, not just their sum. The appearance of a set of localized states in graphene’s VB related to the molecular orbitals of the introduced functionalities was signified both experimentally and theoretically. Applying the density functional theory calculations, the impact of the localized states corresponding to the molecular orbitals of the hydroxyl and epoxide groups was decomposed. Altogether, these findings unveiled the particular contribution of the epoxide and hydroxyl groups to the core-level spectra and band structure of graphene derivatives, advancing graphene functionalization as a tool to engineer its physical properties.

A set of GaAs whisker crystallites in the shape of hexagonal prism with the axis along the [111] direction have been modeled as well as constructions consisting of such prisms. For these model samples XRD patterns have been calculated. Basing on the calculated XRD pattern analysis, a fitting configuration of prismatic fragments has been built for an atomic array obtained with the help of applying molecular dynamics techniques to the initial model prismatic GaAs crystallite.

Single Al wires from unused AAAC (A50) cables were studied after laboratory fatigue testing, which simulated processes arising in these wires during their operation in the cables of overhead power lines (OPLs) and are valuable for predicting the lifespan of cables of OPLs. These wires, which were either fractured during testing (maximum loads—149.4–155.9 MPa; number of cycles till rupture—83,656–280,863) or remained intact, were examined by X-ray diffraction, electron backscatter diffraction, densitometry, and acoustic methods. An analysis of the structural, microstructural, and elastic-microplastic properties of the wires revealed common characteristics inherent in the samples after operation in OPLs and after fatigue tests, namely a decrease in the integral and near-surface layer (NSL) densities of the wires, a decrease in their Young’s modulus and microplastic stress, and an increase in the decrement. However, the tests did not fully reproduce the environmental influence, since in contrast to the natural conditions, no aluminum-oxide crystallites were formed in NSLs in tests and the microstructure was different. A comparison of the characteristics of the broken and unbroken wires allows us to suggest that the fastening locations of the wires are crucial for their possible failure.

Presented results of active resistance frequency dependence measurements of a circular cross-section aluminum and copper conductors with a various diameter in a wide frequency range from 20Hz to 2MHz. Using the skin effect simulation we show that for all types of wires an increased active resistance observed, compared to the theoretical values in the frequency range above 200 kHz, where the skin layer thickness becomes less than 200 μm. This phenomenon may be associated with the manufacturing process of a metal wire by drawing through a die, when defects are formed in the near-surface layer, leading to its increased resistivity.

The facile synthesis of biografted 2D derivatives complemented by a nuanced understanding of their properties are keystones for advancements in biosensing technologies. Herein, we thoroughly examine the feasibility of aminated graphene as a platform for the covalent conjugation of monoclonal antibodies towards human IgG immunoglobulins. Applying core-level spectroscopy methods, namely X-ray photoelectron and absorption spectroscopies, we delve into the chemistry and its effect on the electronic structure of the aminated graphene prior to and after the immobilization of monoclonal antibodies. Furthermore, the alterations in the morphology of the graphene layers upon the applied derivatization protocols are assessed by electron microscopy techniques. Chemiresistive biosensors composed of the aerosol-deposited layers of the aminated graphene with the conjugated antibodies are fabricated and tested, demonstrating a selective response towards IgM immunoglobulins with a limit of detection as low as 10 pg/mL. Taken together, these findings advance and outline graphene derivatives’ application in biosensing as well as hint at the features of the alterations of graphene morphology and physics upon its functionalization and further covalent grafting by biomolecules.

During operation, cables of overhead power lines (OPLs) are exposed to the impact that differs in separate parts of the OPL span due to the different responses of cables near the clamps and far from them. This paper presents the results of a study of aluminum and steel wires cut from such separate parts of ACSR cables before and after exploitation. Structural, microstructural, and elastic–microplastic properties of wires and their changes during operation were studied through optical microscopy, energy-dispersive X-ray microanalysis, electron backscattering diffraction, X-ray diffraction, densitometry, and acoustic measurements. The characteristics of the properties of the wires along the span were found to change in a coordinated manner. Numerical estimates of the influence of the steel core on aging the ACSR cable were obtained. Changes in the properties of the wires, as well as oxidization and corrosion of their near-surface layers, were studied in detail. Quantitative values of the characteristics of properties, the most distant from those observed in the new wires, were revealed for samples of aluminum and steel wires cut from the cable at 1/4 span and near clamps. It is assumed that these cable parts should be the most crucial for cable durability.

Overhead power-transmission lines are one of the most important components of modern infrastructure. Their service life is determined by the state of the near-surface defect layers (NSDLs) of wires constituting these lines. Both the structure and microstructure of the NSDLs of wires of the AAAC type (All Aluminum Alloy Conductor), which were in operation during 0 (new) to 62 years, were investigated by methods of the X-ray (XRD) and electron back-scattering diffraction, optical microscopy, and resistivity measurements, as well as by means of densitometric and acoustic measurements with layer-by-layer removal of the near-surface material by etching. Two characteristic thicknesses of the NSDLs were obtained, different methods providing close results, namely, ~30–50 μm and ~56–140 μm. According to the mass-density distribution (XRD), these characteristic thicknesses correspond to the depths from the surface where they occur, respectively, ~70% and ~99% of the density drop in comparison with the bulk density value. The rate of increase in NSDL thickness is ~4 μm/year in the interval from 0 to 18 years. Results of investigation of elastic and microplastic properties of wires after removal of ~35 μm of the upper layer are also presented.

In modern economic infrastructure, Al cables of overhead power transmission lines are used both without and with a steel core (respectively, all aluminum alloy conductor (AAAC) and aluminum conductor steel reinforced (ACSR) cables). In this article, the changes in structural, microstructural, and elastic-microplastic properties have been analyzed for the outer wires of the AAAC (A50) and ACSR cables (AC50/8 cables with a steel core of ~8 mm2 cross-section, hereinafter referred to as AC50) with the cross-section of the stranded conductor of ~50 mm2, which were in operation for 0–20 years in the Volgograd region of Russia. Using the techniques of X-ray diffraction, electron backscattered diffraction, densitometry, and the acoustic method, the structural and microstructural features of the wires have been compared and found to be correlated with their elastic-microplastic properties. It has been ascertained that the presence of a steel core in AC50 leads to a decrease in the defectiveness of the near-surface layer of their aluminum wires. Compared with A50 cables, the development of void defects in the near-surface layer of Al-wires of AC50 cables slows down (by ~1 year with a service life of ~10 years and by ~3 years with a service life of ~20 years).

Graphene derivatization to either engineer its physical and chemical properties or overcome the problem of the facile synthesis of nanographenes is a subject of significant attention in the nanomaterials research community. In this paper, we propose a facile and scalable method for the synthesis of thiolated graphene via a two-step liquid-phase treatment of graphene oxide (GO). Employing the core-level methods, the introduction of up to 5.1 at.% of thiols is indicated with the simultaneous rise of the C/O ratio to 16.8. The crumpling of the graphene layer upon thiolation without its perforation is pointed out by microscopic and Raman studies. The conductance of thiolated graphene is revealed to be driven by the Mott hopping mechanism with the sheet resistance values of 2.15 kΩ/sq and dependable on the environment. The preliminary results on the chemiresistive effect of these films upon exposure to ethanol vapors in the mix with dry and humid air are shown. Finally, the work function value and valence band structure of thiolated graphene are analyzed. Taken together, the developed method and findings of the morphology and physics of the thiolated graphene guide the further application of this derivative in energy storage, sensing devices, and smart materials.

The effect of wind on the wires of overhead transmission lines leads to their vibration, as well as oscillations of different amplitudes. At places where the wire is suspended, damage to the metal structure of the fatigue type occurs. This is an excessive number of vacancies, dislocations, grain boundaries and blocks compared to the equilibrium one. The defective structure degrades in the direction of the formation of micro-gaps and cracks. The generation and development of the damage zone occurs from the surface of the wire. To prevent a rupture, it is necessary to monitor the development of this zone during the operation of the line without dismantling the wire. To improve the accuracy of assessing the level of accumulation of fatigue damage, the limiting states of the wire, it is recommended to develop methods based on measuring the electrical resistance of the wire material during the development of fatigue damage. A method for monitoring the state of the surface layer by measuring electrical resistance at high frequencies is proposed. The thickness of the controlled layer is determined by the frequency of the measuring signal due to the presence of a surface effect. For effective control, the depth of penetration of the field into the conductor must be commensurate with the thickness of the defective layer. For experimental research, samples were taken of a new wire and wires after various periods of operation on existing lines. According to the results of static tests, the tensile strength and the degree of nonlinearity of the tensile curve were determined. The results of experimental studies of fatigue strength and surface electrical resistance of a separate aluminum wire of A50 conductor are presented. The samples were tested for fatigue under loads close to the conditional endurance limit. The surface resistance of the wires was measured before and after fatigue tests in the frequency range 200 Hz – 2 MHz. The studies have shown the dependence of surface resistance on the degree of development of fatigue damage, which can be used to diagnose the accumulation of fatigue damage.

Few-layer graphene on β-SiC(001) functionalized with phenazine dye Neutral Red by means of diazonium chemistry has been studied using X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, photoemission electron microscopy, scanning tunneling microscopy, and density functional theory calculations. The experimental data reveal the formation of a composite phenazine dye/graphene structure with a large energy gap. The molecules in this structure can be oriented both parallel and perpendicular to the graphene surface. According to scanning tunneling spectroscopy and theoretical calculations, the density of electron states in different surface areas depends on the local short-range order and the molecules’ environment. On the other hand, the photoemission spectroscopy study shows that the bottom layers of the few-layer graphene remain intact, which inherently makes the synthesized layered composite a low-dimensional metal/semiconductor heterostructure. In addition, photoemission electron microscopy imaging shows a high homogeneity of the dye-modified graphene on a micrometer scale.

Представлен новый способ использования детонационного наноалмаза с положительным и отрицательным знаком дзета-потенциала в качестве разделителя для аэрогелей на основе оксида графена. Показано, что дозированное добавление в суспензию оксида графена гидрозоля частиц детонационных наноалмазов позволило троекратно увеличить удельную поверхность образующегося аэрогеля по сравнению с аэрогелем оксида графена, и этот эффект значительнее при использовании наноалмазов с положительным дзета-потенциалом. Также показано, что полученные из оксида графена и детонационного наноалмаза с положительным дзета-потенциалом аэрогели обладают специфической морфологией: пластины оксида графена при этом скручены. Этот эффект обсуждается с точки зрения изменения среднего дзета-потенциала исходных смесей. Ключевые слова: двухкомпонентные системы, углеродные материалы, коллоидная химия.

Derivatization of 2D materials for bioapplications is at the forefront of nanomaterials research nowadays. Facile synthesis of the biografted 2D derivatives and insight into the conformation of the conjugated biomolecules are two pillars, promoting advances in the field of biosensing, drug delivery and regeneration techniques. This work is devoted to the synthesis and conjugation of carboxylated graphene by aptamers followed by theoretical analysis of their conformation in the immobilized state. Employing the developed method, the hole-matrixed graphene with up to 11.1 at.% reactive carboxyl groups was synthesized and thoroughly examined via core-level spectroscopy and time-resolved methods. The mechanism of the performed carboxylation with conversion of graphene oxide into carboxylated graphene is proposed, unveiling commonly disregarded impact of ether-like components to the fingerprints of the carboxyl groups. We show successful covalent immobilization of the AO-01 aptamer against Hepatitis B protein on the synthesized C-xy graphene and for the first time reveal its conformation both in free and immobilized forms via a combination of density functional theory (DFT) calculations and molecular dynamic (MD) modeling. Taken together, these results advance the application of graphene derivatives grafted with the biomolecules in the field of biosensing.