Seznam abstraktů 2019: POSTEROVÁ SEKCE A

No-additive high-temperature/high-pressure nanopowder sintering benefits by making pure ceramics with no binder. The combination of semiconducting/electronic properties of gallium nitride GaN with insulating and heat-conducting properties of aluminum nitride AlN, including possible AlxGa1-xN solid solutions, may yield an unusual set of functional properties of the composite nanoceramics.
NH3-mediated reactions in only briefly stirred hexane solution of both metals tris(dimethylamides) yielded a mixture of polymeric gallium imide and aluminum amide-imide. Ammonolysis of such a bimetallic precursor at 800 and 950 ºC resulted in the in-situ formed and intimately mixed 1:1 composite nanopowders NP800 and NP950 made of AlN (Dav = 1-2 nm) and GaN (Dav = 25-110 nm). 3-minute sintering of the nanopowders at 7.7 GPa and 650, 850 or 1000 ºC resulted in black ceramic disks (D = 4 mm, h = 2 to 4 mm). Their structural and close range ordering was examined by XRD and 27Al/71Ga MAS NMR. Sintering at the lower temperatures did not cause any nitride recrystallization/reactions whereas at 1000 ºC some AlxGa1-xN was additionally detected.
The mechanical properties were probed by the Vickers hardness test, HV, on polished disks. For sintering of NP800 at 650 or 850 ºC, HV was found in the range 12-13 GPa and at 1000 ºC it was 9.5 GPa. Sintering of NP950 at 650 or 850 ºC yielded HV in the range 11-14.5 GPa and at 1000 ºC it reached 15 GPa. These HV values favorably compare to those for single crystals of AlN, 10-18 GPa, and GaN, 10-12 GPa.
ACKNOWLEDGEMENT: Funded by Polish NCN Grant No. 2017/25/B/ST5/01032.

A novel two-step pathway towards sulphur-doped graphitic carbon nitride (CN) was hypothesized and practically tested. As a result of that, three new materials with the different content of sulphur (up to 0.023 wt.%) were synthesized. These materials were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRFS), Fourier transform infrared (FTIR) and Raman spectroscopy and UV-Vis diffuse reflectance spectroscopy (DRS) all of which were compared with materials coming from procedures known in literature. Furthermore, photocatalytic properties of gained materials towards the decomposition of acid orange 7 (AO7) were tested and compared to known materials as well. All of three materials show less S-enrichment than CN (SCN) obtained by established procedures from thiourea, on the other hand, they bear a remarkable photocatalytic properties in photodegradation of AO7.

Preparation, size control, and characterization of nanodiamond (ND) particles down to a few nm is still challenging and highly demanding for biomedical and optoelectronic applications. Here, the dependence of surface chemistry on ND particle size in the 1-3 nm region was investigated.
We used high-pressure/high-temperature, oxidized NDs (HPHT O-NDs) and size-reduced hydrogenated (H-) as well as oxidized (O-) detonation NDs (H/O-DNDs). Three size fractions in the 1-3 nm region were obtained from each ND sample by varying ultracentrifugation time of ND hydrocolloids. For accurate size distribution characterization of the obtained fractions analytical ultracentrifuge (AUC) was used.
Size-dependent chemical composition and bonding chemical states of ND samples were studied by X-ray photoelectron spectroscopy (XPS). We found that in case of oxidized NDs the oxygen concentration increased with decreasing size. Deconvolution of C 1s core levels revealed increase of sp2/sp3 bond ratio with decreasing size and change of surface chemistry from oxidized to hydrogenated DNDs. Similar effect was confirmed by reflection electron energy loss spectroscopy (REELS): The surface plasmon loss intensity was enhanced for smaller ND particles.
Fourier transform infra-red spectroscopy (FTIR) analysis of the ultra-small H-DND and O-DND suggests, that with decreasing DND size the typical core-shell DND structure disappears. This is documented by overall significant change of surface chemistry with decreasing size of both H-DND and O-DND and mainly by gradual decrease of the volume-related 1331 cm-1 band assigned to N-induced one phonon mode originated from the diamond core lattice. In contrast, any significant size-dependent trend of surface chemistry of the ultra-small HPHT NDs particles was not observed by FTIR.

Carbon nanotubes (CNTs) and titanium dioxide (TiO2) composites have become a promising hybrid nanomaterial for applications like photocatalysis, gas sensors and energy storage. These nanostructures combine the high surface area and excellent thermal and electrical conductivity of the CNTs with the high photoactivity and chemical stability of TiO2. Multi-walled carbon nanotubes (MWCNTs) were grown by catalytic chemical vapor deposition method. The grown MWCNTs were plasma modified in two ways: oxygen treatment and carboxyl polymer coating and were subsequently coated by atomic layer deposition (ALD) of TiO2 from tetrakis(dimethylamido)titanium. Oxygen plasma treatment provided defect sites for nucleation and growth of TiO2 and carboxyl polymer film improved the uniformity of the film. These modified MWCNTs were tested for their sensing behaviour towards NH3 and NO2 gases and exhibited an improved response as compared to pristine CNTs. Structural properties of pristine and modified MWCNTs were characterized by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). Scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy (STEM-EDX) confirmed the presence of TiO2 on nanotubes

Colloidal semiconductor quantum nanocrystals (quantum dots) of the IR range have already found wide application for creating light-emitting, photoreceiving, and photovoltaic devices. The recently discovered 2D quantum semiconductor nanoplatelets have a number of advantages over nanocrystals with three-dimensional quantum confinement and can be the basis for creating light-emitting devices of a new generation: narrow photoluminescence bands, large oscillator strengths and an increased radiative relaxation rate of excited carriers make nanoplatelets promising for use as active media optoelectronic devices. The development of methods for the colloidal synthesis of nanoplatelets for the near IR range is still at an early stage, and in the past few years there have been reports on the synthesis of nanoplatelets based on cadmium chalcogenides, lead and mercury, luminescing in the spectral range 0.75-1.1 microns. These new nano-objects are among the most promising materials for the creation of new photo-receiving and light-emitting devices in the near-IR range.
The aim of the research is to develop near-infrared light sources based on semiconductor quantum nanoplatelets which will ensure the transition to new production technologies for creating light-emitting devices based on fundamentally new materials and will also lead to the widespread introduction of modern information processing, transmission and storage systems. ACKNOWLEDGEMENTS: This work was supported by the Russian Science Foundation (Grant no. 19-13-00332).

We propose switching molecular diode based on endohedral fullerene systems (MX@C70). Encapsulated molecules with general formula MX (M - metal, X - fluorine, chlorine, oxygen) were used. We show that relative orientation of enclosed molecules can be controlled by oriented external electric field. We suggest a four-terminal system of electrodes, in which two electrodes (main) are used to help current pass through the system while the other two electrodes (gate) lower the barrier of rotation by stabilizing the transition state of rotation. Non-equilibrium Green's function was used together with density functional theory (DFT-NEGF) to study the dependence of conductivity on orientation of the enclosed molecule. Based on our results, orientation of the MX can be both enforced ("written") and retrieved ("read") by applied voltage. The studied systems thus behave like voltage-sensitive switching molecular diodes suitable for application in random access memories for short-term or memristors for long-term data storage. This depends on the energy barrier for the MX switching in the absence/presence of an external electric field, i.e. the lifetime of the states.

Quantum computing is an increasingly popular area of research and innovation. It implements approaches directly profiting from quantum-mechanical nature of matter at the nano-scale. Importantly, it is believed that quantum computers will surpass the efficiency of classical computers in near future. A wide range of problems in condensed matter physics and chemistry could be solved by quantum computers. Nowadays, it is possible to simulate quantum systems on quantum computers with the help of the QASM simulator by IBM. Moreover, IBM provides a cloud-based quantum computing platform (IBM Quantum Experience) offering five-qubit and fourteen-qubit quantum processors for a real run. In our study, we focused on the quantum simulation of negative hydrogen ion [1]. We perform the simulations of the H- ground state energy using Variational Quantum Eigensolver (VQE) that is implemented in framework QISKit for quantum computing. Simulations were performed on the QASM simulator and also on five-qubit devices “ibmqx2” and “ibmqx4”. In order to obtain the ground state energy of the negative hydrogen ion we used several optimization methods, which are both local [1] and newly also global, to converge energy of the system to the energy minimum. REFERENCES: [1] S. Kumar, R. P. Singh, B. K. Behera, P. K. Panigrahi, https://arxiv.org/pdf/1903.03454.pdf.

This research concerns nanoscale plasticity in dislocation-free nanovolume of Si, GaAs and InP semiconductor crystals. The nanoindentation experiments and quantum ab-initio calculations were used to determine a phenomenon responsible for an elastic-plastic transition in selected semiconductors, marked by so called pop-in event represented by a characteristic discontinuity in a load-displacement curve. We considered effect of doping and effect of loading rate on a pop-in contact pressure. Consequently, it was shown that the nanoindentation induced plastic deformation of InP crystal is initiated by dislocation nucleation. In contrasts the phase transformation governed elastic-plastic transition was detected in Si and GaAs. Our study provide a convenient way to identify the mechanism of incipient plasticity in semiconducting crystals.

ZnO nanorods have attracted increasing interest in recent years due to their potential in optoelectronic applications. The lack of p-type ZnO emphasizes the importance of rectifying junctions realized on other p-type materials. SiC is a good candidate to create hybrid heterojunctions with ZnO due to its wurtzite crystal structure and a small lattice and thermal mismatch. The ZnO/SiC heterojunctions have a potential to show intense UV electroluminescence. We investigate morphology and electrical properties of a single vertically-oriented ZnO nanorod on a SiC substrate. The current-voltage measurements are performed directly in the vacuum chamber of a scanning electron microscope. The contact to a single nanorod is obtained by a nanoprobe, which allows for the measurement of the current-voltage characteristic of a single nanorod heterojunction of choice. The influence of ZnO growth parameters and post-growth treatment of ZnO/SiC structures are studied with the aim to minimize the density of structural/interfacial defects and to create low-dimensional hybrid heterojunctions with the potential to show intense UV electroluminescence.

In this work, a stable suspension recipe and the optimal mode for EPD process are presented. The possibility of precision control of the thermite material composition in electrophoretic deposition technology is considered. The wave combustion reaction occurs in the composition range from 17 % to 53 % wt. CuOx content in deposited layer. The obtained Al-CuOx samples show high density of the released energy: 2407 J/g in air atmosphere and 1954 J/g in argon atmosphere measured by DSC. The velocity of combustion wavefront propagation determined by high-speed video camera reached 3.5 m/s.

“Flavines” (isoalloxazines) are a group of naturally occurring materials which are biological photoreceptors. Due to their remarkable chemical properties and high versatility, these non-toxic, low-cost, biocompatible, and sustainable materials have been already considered as bio-organic semiconductors for future bioelectronics applications. In this study, we present nine different N,Nʹ-alkylated flavine molecules which are synthesized by direct alkylation of already synthesized non-alkylated derivatives. Alkylation was provided by using CsCO3 as a base in DMF at 90°C. Crude products were purified by column chromatography on silica gel and final molecules were obtained in moderate yields. We performed comprehensive chemical and physical characterizations of the molecules to evaluate the role of the modification of the initial alloxazine core with several aromatic substituents and the effect of short linear, bulky, and oligoetheric substituents on the molecules’ properties.
We also prepared thin films using spin-coating and physical vapor deposition techniques. The flavines in thin films were characterized by optical, electrical, electrochemical, and morphological measurements. We evaluate the potential applications of these unique molecules in organic electronic devices.
Acknowledgment: The work was supported by the Ministry of Industry project TRIO No. FV20022

The increased level of industrial pollutants in water and drug resistant pathogens are serious threat to human and aquatic life. Graphene based materials are an attractive choice due to numerous fascinating features of graphene. However, combining graphene with other nanomaterials in the form of nanocomposites give a window of opportunities to fabricate and investigate new materials. Herein, graphene based nanocomposites are presented that are combination of graphene and metal/non-metal oxides. These nanocomposites are synthesized, systematically characterized and are compared for their performance in environmental and biomedical applications. These have shown significant potential for complete eradication of bacteria and removal of synthetic dye.

The development of electronic technologies and the requirement for high-speed electronic systems and devices have led to an increased improvement in the performance of electronic and telecommunication devices (mobile phones, wireless or navigation systems etc.). Long-term exposure to electromagnetic (EM) fields poses serious risks to human health (EM pollution). EM shielding materials like traditionally-used metals need to be replaced with lighter materials, which also achieve the sufficient mechanical strength and resistance.
This work deals with the topical problem of developing non-metal composites (geopolymer composites) with the aim to increase their EM shielding capabilities. Geopolymer composites consist of carbon or basalt fiber grids (size 1612; 2222 or 3434 mm) and nanoparticles of MgO (concentration 0.0; 5.0; 7.5 or 10 %) incorporated into the matrix. Carbon (CF) and basalt fibers (BF) from roving were soaked in various different solutions (distilled water, calcium hydroxide, sodium water glass, and potassium water glass) for two weeks, six weeks and three months, and their tensile strength was examined.
The shielding efficiency (SE) of sheet materials (with different fillers) was evaluated in the 30 MHz - 1.5 GHz frequency range. The electromagnetic SE was 5 dB for the pure geopolymer material (without any modification) and reached up to 32 dB for the geopolymer material with CF grids. Moreover, the modified composite material achieved different SE for altered frequencies. The results reveal the possibility to use the composite geopolymer material in the production of shielding coatings with lower costs and with environmental considerations.

The results of γ-irradiation treatment of activated carbons prepared from Peach stones with H3PO4 chemical activation at different impregnation ratio are presented and investigated through comparing the variation of the physical and structural properties of the activated carbons before and after γ-irradiation treatment. The weight-ratio in a range of 0.5-2 wt% is used to prepare activated carbons and the as-prepared samples are exposed to gamma radiation doses of 50 and 100 kGy. Microstructural changes in the surfaces of the carbons samples were investigated using scanning electron microscopy, Brunauer-Emmett-Teller, Fourier transform infrared spectra analysis and X-ray Diffraction. The results show that the gamma radiation affected the pore structure of the carbons and surface areas of irradiated carbons are measured to be greater than those of non-irradiated carbons. The functional groups of irradiated carbons were not significantly affected by gamma irradiation but their intensity was found to decrease significantly due to the damages induced in the carbons structures after irradiation. The scanning electron microscopy analysis showed that the interaction between the gamma-irradiation caused remarkable erosion on the carbon's surface and destroyed the nanostructure of carbons, leading to the enhancement of porosity due to the loss of carbonaceous matter from the surfaces of the carbon.

The relation between plasma temperature and properties of graphene nanosheet layer deposited on Si/SiO2 substrate by decomposition of ethanol in microwave plasma torch discharge at atmospheric pressure was investigated in dependence on delivered microwave power and gas flow rates. Plasma modelling was carried out using COMSOL Multiphysics software with delivered microwave power, gas flow rates and experimental reactor geometry as input parameters. Results of the heat flow and fluid dynamics modelling were compared with substrate temperature measured by thermocouple integrated in quartz tube substrate holder. The graphene nanosheets layer was characterized by SEM, Raman spectroscopy and 4-point probe method. The layers were severals tens of μm thick and their sheet resistance varied from 2 to 40 kΩ/sq. The properties of individual graphene nanosheets, 2D/G and D/G Raman band ratio, as well as the sheet resistance of their conductive network were correlated with the increase of plasma temperature with increasing microwave power. The substrate temperature increased linearly with delivered microwave power and the layer sheet resistance was decreasing with increasing microwave power and saturated at 2 kΩ/sq and D/G ratio of 0.6.

Scanning electron microscopy was used to determine physical properties of microwave plasma synthesized graphene nanosheets such as size and shape under various electron beam parameters (accelerating voltage, electron beam current, working distance). The stability and amount of defects of graphene nanosheets structure was investigated in dependence on these parameters and the results were compared to data obtained by TEM and Dynamic light scattering (DLS). Electron beam irradiation lead to change of nanosheets topography and defect formation was observed as well. The amorphization of the carbon nanostructure led to increase of intensity of D band (1360 cm-1) in Raman spectra. Contrary to electron beam irradiation damage the high temperature annealing, up to 800 °C, in Ar led to no observable changes.

On the basis of arc metal deposition process the technology for carbon nanotubes (CNT) addition to metal was developed. It uses extruded metal rods with CNT’s as additional material. For this study the developed technology was used for modification of metal Al-5Mg alloy. Comparison of macro- and microstructure for metal obtained with developed technology with CNT’s and without it shows no strong difference for modified and not modified metal. Nevertheless CNT’s were observed in modified metal with use of SEM and analysis of microhardness showed that addition of CNT increases microhardness in upper layers of deposited metal.

Carbon dots are new materials with capability in bioimaging, optical device, catalysis, and many other fields. Their advantages, such as ease of large-scale preparation, low cost of precursor, highly tunable photoluminescence, satisfactory biocompatibility, and photostability against photobleaching, make them competitive alternatives to conventional semiconductor-based quantum dots and organic dyes. In order to overwhelm other luminescent materials in applications, their functionalities are still needed to be improved in spite of the above mentioned advantages. In recent years, it has been proved that initial precursors were an effective approach to improve the optical and electronic performance of CDs via tuning their carbon skeleton matrices and the chemical structures. In this work, a green and efficient strategy was developed for one-step synthesis of carbon dots using 1,-2,-3 -trihydrobenzene, Influence of different organic solvents have been evaluated for one-step synthesis of carbon dots using dimethylformamide, formamide, ethylenediamine and their mixtures in the presence of 1: 1. The as synthesized carbon dots are demonstrated to possess redshifted photoluminescence, excellent optical properties and higher photostability. It is demonstrated that the increase of the nitrogen content in the solution leads to the red shift of the photoluminescence band and increase of the crystalline phase inherent to amorphous carbon.
This work has been supported by the Ministry of Education and Science of the Russian Federation (Grant 14.Y26.31.0028).

Photonic (nano-) structures are periodic systems artificially designed in 1D, 2D or 3D shapes for monitoring, controlling or modification of light inside the structure. However, the fabrication of periodic and uniform nanostructures is still a challenging task, especially for material like diamond. Diamond with its outstanding chemical and physical properties as well as impressive optical properties, such as a relatively high refractive index (2.41), large optical transmission window from the UV well into the mid IR and possibility to host a variety of optically active colour centres (e.g. nitrogen, silicon, erbium) has been an eligible material for the realisation of optical elements including 2D photonic structures. Although monocrystalline diamond is a better candidate than polycrystalline diamond, the production and machining of monocrystals is quite cumbersome. On the contrary, the polycrystalline diamond film with desired properties (morphology, size of grains, thickness) can be grown easily and inexpensively. Here, we demonstrate two different technological approaches for fabrication of polycrystalline diamond-based photonic nanostructures comprised of triangular lattices of air holes. First, a simple and easy method based on microsphere lithography allowing large area (units of cm2) structuring will be pointed out in sense of critical technological issues. Second, a more precise but at limited area (units of µm2) processing represented by electron beam lithography will be demonstrated. In both cases, the acquired technological advances show promising route for practical application of polycrystalline diamond in photonics.

We fabricated the hybrid quantum dots light-emitting diodes using quantum dots and organic phosphorescent molecules to emit highly efficient white emission. The double emitting layers were stacked directly without any buffer layer. The device has a luminance of 20,453 cd/m2 and current efficiency of 9.61 cd/A. It is one of the promising results so far for white emission QLEDs.

We report the fabrication of thick nanoporous oxide films on stainless steel (SS) foils via long-term constant-potential anodization at room temperature. The anodization potential of 50 V was employed for 1, 2 and 3 h, respectively to form the anodic films with different thickness. The effects of anodic film thickness on supercapacitance behavior have been further investigated as binder-free electrodes. It is found that the anodic film thickness increases linearly with the anodization time while the electrochemical behaviors of anodic film were not proportionally enhanced with the thickness. Furthermore, the formed anodic layers formed at 50 V/3 h exhibits the highest area capacitance ~ 215 mF cm-2 at 1 mA cm-2, and the capacitance still retained 58.9 % of its initial value after 1000 cycles.

The main objective of this work is the study of the structural and optical properties of SiO2/TiO2 Bragg reflectors obtained by the sol-gel method using the dip-coating technique. Within this work the effect of the annealing, the number of bilayers and the nickel concentration on the structural and optical properties of SiO2/TiO2 is investigated. For this reason, the following analytical techniques were used: X-ray diffraction (XRD), Raman spectroscopy, UV-Vis spectroscopy and photoluminescence (PL).
X-ray diffraction and Raman spectroscopy showed that all samples crystallize according to Anatase phase, except the non-annealed sample because it is amorphous. We also found that the grain size (D) increases as annealing temperature increases while it decreases with the increase of the number of bilayers and the nickel (Ni%) content.
UV-Vis results indicates a shift of the transmittance (T%) spectra headed for shorter wavelengths under the effect of annealing and doping (5% Ni). Further, the number of bilayer and doping TiO2 with 2 at.% of nickel shift the transmittance spectra towards longer wavelengths.
These results revealed that the shift to longer or shorter wavelengths may be, respectively, associated to the diminishing and the augmentation of the grain size (D). Also, The transmittance coefficient (T%) and the band gap (Eg) are inversely proportional to grain growth (D).
In addition, doping with nickel (Ni) intensifies photoluminescence spectra and shifts them towards longer wavelengths. This is due to the formation of gap trapping levels (Eg) and the increase of the electron-hole recombination rate.

MOVPE GaN/InGaN quantum well structures are very promising for scintillator structures, which are core of detectors, which are a fundamental part of many devices like computer tomography, electron microscopes, colliders for elementary particle study and many other applications.
Study of photo- and cathodo-luminescence (PL, CL) parameters including of time resolve behavior of scintillator structures is an irreplaceable measurement techniques tool for understanding of future scintillator properties and for optimization of required nano-hetero structures. Nevertheless, for technology of structure preparation, it is indispensable to know which defects or impurities are responsible for given spectral peaks or bands of PL and CL spectra as well as to understand their nature.
Secondary ion mass spectrometry (SIMS) analysis is a powerful tool for determination of many impurities at different parts of structure with a several nm resolution and down to 10-16 cm-3 for many elements.
On the other hand, PL can confirmed which from elements measured by SIMS are responsible for which spectral peaks or bands measured by PL or CL. It can be conclusive/strong prove, when we can be able to change impurity concentration intentionally.
Some examples of SIMS measurements, commercial (EAG US company) and at Czech Republic available, and related PL and CL of our structures will be presented.

An in situ investigation has been carried out by X-ray diffraction of the evolution of the crystallite size and the microstrain of low-temperature annealed commercially pure titanium grade 2 in the state after machining and polishing. Annealing was performed in vacuum at a temperature of 300, 400 and 500 °C, with various dwell times. The results presented here demonstrate that annealing temperatures lead to a significant reduction in microstrain and enhanced crystallite growth. The effect of the dwell time is more pronounced at temperatures above 400 °C. The dwell time at a temperature of 300 °C affects the crystallite growth but produces no microstrain relaxation. The presented results can be very useful for optimizing the working cycle and cooling during surface modification of titanium or exposed machines parts in order to improve the stability of the microstructure and extend the lifetime of components.

Polyester urethane polymer was synthesized as linked biocompatible poly (lactide)/poly (ethylene oxide) polymers. The bulk polymer was subsequently used as precursor material for plasma assisted vapour thermal deposition of thin plasma polymer films under varying RF discharge power. The effect of plasma polymerization on the final physico-chemical characteristics was investigated. The chemical analysis of the films was performed using X-ray photoelectron spectroscopy and infrared spectroscopy. Structural analysis of plasma polymer thin film revealed the similar molecular structure as in case of precursor since PEU-characteristic bonds were preserved after the plasma polymerization. Surface properties analysed by a contact angle measurement revealed an increase of wettability in the samples prepared at higher RF power. At the same time a surface energy evaluated according to acid-base model decreased. The results indicate that plasma polymer films properties could be tuned depending on applied deposition conditions.

Magnetic nanoparticles experience magnetic force under the magnetic field. The magnetic force can be measured as the magnetic weight of the magnetic nanoparticle sample with a conventional electronic balance. The instantaneous jump of the magnetic weight by the Neel and the Brown mechanisms is observed when the magnetic sample is placed under the magnetic field. The magnetic weight increases slowly thereafter as the nanoparticles agglomerate. During the slow increase of the magnetic weight, the magnetic weight fluctuates with the change of temperature. When the temperature rises, the magnetic weight decreases, and vice versa, which suggests that the magnetic weight could be used as a thermometer. The thermal fluctuation of the magnetic weight results from the structural relaxation of the agglomerate by the kinetic energy of nanoparticles. We propose a simple equilibrium model for the thermal fluctuation of the magnetic weight, which explains the fluctuation in terms of the free energy difference between the agglomerated and the dispersed nanoparticles. The structural relaxation of the agglomerate is a complex process because many different clusters are formed during the agglomeration. In order to understand the details of the thermal fluctuation of the magnetic weight, the energy landscape picture with the distribution of the involved free energy is required.

In this contribution, magnetic Fe2O3 nanoparticles (MNPs) were successfully incorporated into the polyvinyl butyral (PVB) nanofibrous membranes using the electrospinning process. The effects of the MNP concentration on the morphology of the nanofibres and their magnetic properties were investigated. Scanning electron microscopy and transmission electron microscopy confirmed their concentration-dependent, yet uniform diameter, and the presence of well-embedded MNPs inside the PVB nanofibres. The magnetic properties of the PVB/MNP membranes were studied using the vibrating-sample magnetometry. The saturation magnetization increased from 6.4 to 45.5 emu/g as the MNP concentration in the feedstock solution increased from 1 to 15 wt%. The fabricated PVB/MNP nanofibrous membranes possessed the ability to respond to the external magnetic fields, which determines their potential in the development of the advanced smart textiles.

The phase diagram of the alloy nanoparticles (nanoalloys) were investigated by CALPHAD method. The binary nanoalloys Ag-Au, Ag-Ni, Au-Ni, Ni-Pt and AuPt were predicted with respect to nanoparticle size and temperature. The thermodynamic approach was developed by surface contribution for different shapes of particles. There is presented combination of fully miscible system Au-Ag with two fully immiscible systems Ag-Ni and Au-Ni. The calculation was completed by theoretical values of surfaces energy and cohesive energy from density functional theory (DFT).
ACKNOWLEDGEMENTS: This research has been financially supported by the Ministry of Education, Youth and Sports of the Czech Republic under the Project CEITEC 2020 (Project No. LQ1601) and by the Czech Science Foundation under the Projects “Stability and phase equilibria of bimetallic nanoparticles” (Project No. GA14-12653S) and “Structure and properties of selected nanocomposites” (Project No. GA 16-24711S). Computational resources were provided by the Ministry of Education, Youth and Sports of the Czech Republic under the Projects CESNET (Project No. LM2015042), the Project CERIT Scientific Cloud (Project No. LM2015085) and by IT4Innovations National Supercomputer Center (Project No. LM2015070) within the program Projects of Large Research, Development and Innovations Infrastructures.

The work will describe methods for the production of nanoparticles for further use as a basis (skeleton) for the creation of new medicinal or neutral antiseptic agents.
The main method used during the work was laser ablation of gold, silicon, and germanium targets placed in water or acetone. Ablation in water and in acetone was performed by femtosecond pulses of a titanium-sapphire laser (Avesta). The method of mechanical grinding of silicon and germanium plates to obtain nanopowders (particle diameter of fragments of 100-500 nm), which were subsequently processed by femtosecond laser radiation for better crushing, was also considered.
Femtosecond ablation of gold targets in suspensions of silicon nanoparticles yielded stable colloidal solutions of metal-semiconductor Au-Si NPs. NPs consisting of hybrids with narrow size distribution and large gold NPs with Si shells were prepared. An increase in the Au / Si ratio was observed with a decrease in the AuSi size of nanohybrid NPs. Formed NPs have a good spherical shape and their size ranges from a few nm to 70-100 nm. During the ablation of germanium targets in acetone with an excessive presence of silicon nanoparticles from 10 to 50 nm in size, combined Si-Ge particles with sizes of 500 nm or less were obtained, consisting of a germanium core and a shell of small 5-10 nm silicon particles.

This study deals with the effect of star-like zinc oxide (ZnO) filler addition into poly(vinylidene fluoride) (PVDF) matrix on its structural and physical properties with the consequences to mechanical energy harvesting performance. In this case, the microwave-assisted synthesis was optimized for the preparation of unique star-like shape of ZnO particles. Their crystallinity and star-like morphology/elemental composition were analyzed using XRD and SEM/EDX spectroscopy, respectively. The investigation of α-crystalline phase transformation into β-crystalline phase of neat PVDF matrix, and upon introducing various ZnO concentrations was performed using FTIR spectroscopy. Finally, the mechanical energy harvesting capability measurements showed that the addition of star-like ZnO filler enhanced the d33 electro-mechanical coupling coefficient more than two times when compared to neat PVDF matrix.

Perovskites are one of the most intensively studied photovoltaic materials nowadays. Microscopic studies can provide useful information about material roughness, conductivity, structure, mechanical and opto-electronic properties as well as about kinetic effects from short to long time scale for understanding and improving the photovoltaic performance. Here, time-resolved photovoltage was measured by Kelvin probe in the dark and under white light illumination. Morphology was characterized by optical and atomic force microscopy. We identify the impact of charge transporting layers (CTLs) on structural and opto-electronic properties of MAPbI3 perovskite with different ratio of MAI and PbI2.

Nonplanar polyaromatic hydrocarbons possessing curved surfaces, known as geodesic polyarenes or buckybowls, illustrate unique and challenging targets in synthetic chemistry.[1] Because of their interesting properties arising from their curved aromatic system, the research in the field of buckybowls increased fast over the last decades. Due to their high degree of ring strain, these systems show an analogous structure to fullerenes and carbon nanotubes. For instance, the structural motifs of corannulene and sumanene, can be seen as parts of the C60 surface.[2]
Introduction of curvature still remains as the major challenge in the synthesis of buckybowls, due to harsh reaction conditions that tolerate only a few functional groups. Well-defined functionalization of these bowl-shaped molecules set the stage for further derivatization towards key building blocks for rational fullerene synthesis, nanotubes, and other related carbon-based nanostructures.
Recently indacenopicene, another member of the buckybowl-family was synthesized by Wang et Al. using Pd catalyzed aryl-aryl coupling.[3] Although the method is very powerful for the synthesis of large planar molecules, the yield usually drops significantly in case of non-planar systems. Another method was introduced by Amsharov et Al. using aryl-aryl coupling through C-F bond activation.[4] This method was found to be tolerant toward aromatic C-Br bonds.[5] By using this method we synthesized brominated indacenopicene and further derivatization via different Pd catalyzed cross couplings lead to new derivatives of this unique system. REFERENCES: [1] Y.-T. Wu, J. S. Siegel Chem. Rev. 2006, 106, 4843; [2] M. Stepien Synlett. 2013, 24, 1316; [3] L. Wang, P. B. Shevlin Org. Lett. 2000, 2, 23, 3703; [4] K. Y. Amsharov, M. A. Kabdulov, M. Jansen Angew. Chem. 2012, 124, 4672; [5] O. Papaianina, V. A. Akhmetov et Al. Angew. Chem. 2017, 56, 4834.

The development of new solid-state organic luminescent dyes attracts particular interest due to the wide range of their applications in the field of organic solid-state lasers [1], medical treatment and diagnosis [2], optical fibers [3], and solid state dye-labeled DNA [4]. Para-bis(2-thienyl)phenylene as a dye represent perspective alternative for application in abovementioned fields. Here, we focus on the effects of fluorine atoms attached to the central phenyl unit of the para-bis(2-thienyl)phenylenes and the effect of substitutions on the thiophenes units. Generally, incorporating electron-withdrawing fluorine atoms enables HOMO and LUMO energies tuning as well as molecular organization control because of π-stacked supramolecular organization in the solid state due to strong interaction between electron-poor fluorinated aromatic rings and non-fluorinated electron-rich rings [5]. On the other hand, adamantane units bestow high thermal and chemical stability and self-assembly on the molecules what has a crucial effect for the nanoscaled films production for the applications into the functional devices. Substitutions on the thiophene units with adamantylethyl groups significantly increased melting point from 55 °C to 250 °C and photoluminescence quantum yield up to 50 % [6].
With regards to the possibility of well-targeted chemical modifications for the individual purposes, these molecules are determined for the use in organic electronics.

The work was supported by the FCH-S-19-5834

[1] S. Forget, S. Chénais, Springer, Verlag, Berlin, Heidelberg, 2013.
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It is known that magnetic nanoparticles (MNPs) are able to convert the energy of an alternating magnetic field (AMF) into both thermal (in the case of high-frequency fields) and mechanical (low-frequency fields). Affecting with an AMF on a nanoparticle with ligands fixed on it surface, one can induce controlled stretching, compression or change in the shape of organic macromolecules, thereby controlling their catalytic and biological activity. In recent years the scientific field associated with the investigation of the control over the various molecules functions (enzymes, lipids, oligonucleotides, etc.) using MNPs in a low-frequency AMF is actively developed. Due to the low-frequency AMF has a negligible impact on living objects and chemical bonds itself, various systems based on MNPs are developed, which allow to enhance this effect. Being fixed on the MNPs surface brought into motion by an AMF, the macromolecules also undergo the geometrical changes, including conformational ones, which lead to the change in their optical and physicochemical characteristics. As a result, the effectiveness of such nanosystems was proved in magneto-mechanical experiments associated with control drug release, disturbance of enzymic mechanisms and damage of DNA molecules which results in cell death. Nevertheless, despite the large number of theoretical works devoted to the development of platforms based on MNPs for remote control of various molecule functions under the action of a low-frequency AMF, the real quantitative values of magneto-mechanical forces mediated by MNPs with known physicochemical parameters still remain unclear. Moreover, the calculation of such forces is very complex task due to the influence of a large number of physicochemical parameters of system (shape, core and hydrodynamic sizes of MNPs, their magnetic properties, the nature of chemical bond between MNPs and desired chemical molecules etc.).
In this work to determine the magneto-mechanical forces mediated by MNPs in an low-frequency AMF an experimental system was developed, which allowed us to calculate the values of the corresponding forces using known parameters of system including binding energies of model molecules attached to the surface of MNPs. Single-stranded (ss-) oligonucleotides with length from 10 to 60 nucleotides were used as model molecules, which is explained by the possibility of creating duplexes on their basis with precisely known values of the binding energies between individual complementary chains. In turn, the binding energies between complementary chains were varied by selecting their length and nucleotide sequence. Briefly, the essence of the experiment was as follows. First, the technique for obtaining homogeneous single-domain water-soluble MNPs with hydrodynamic size comparable to the size of a single magnetic core was developed. The resulting MNPs contained on their surface the ss-oligonucleotide molecules of maximum length (60 nucleotides) labeled with a fluorescent dye Cy5. After that the oligonucleotide duplexes with different length were obtained by hybridization of fluorescent-labeled ss-oligonucleotide attached to the MNPs surface and complementary ss-oligonucleotides with various length (from 10 to 60 nucleotides), which were firmly fixed onto the surface of the microarray through the formation of covalent bonds. The resulting oligonucleotide duplexes were treated by low-frequency AMF (B≤100 mT and f≤180 Hz) during a certain time. The percentage of mechanically destroyed duplexes under the influence of magneto-mechanical forces mediated by MNPs was estimated by the intensity of the dye fluorescence before and after exposure of the field using microarray laser scanner. The cleavage of duplexes led to the detachment of nanoparticles with fluorescent-labeled ss-oligonucleotide molecules attached to their surface, and, consequently, to a decrease in the fluorescence intensity of the dye at the attachment points of the duplexes to the substrate. Finally, the experimental magneto-mechanical forces were calculated taken into account all physicochemical parameters of the system such as core size and shape of MNPs, their magnetic properties, the oligonucleotide molecule packing density, the percentage of destroyed duplexes with known nucleotide length and sequence, AMF parameters, field exposure time and so on. It was found that the maximum destruction of duplexes was observed in the case of short oligonucleotides (up to 18 nucleotides), under the field with B = 100 mT and f = 180 Hz, which is explained by the relatively low binding energy of complementary chains. Opposite, no effect was observed in the case of duplexes formed by long oligonucleotides (more than 60 nucleotides) at the same conditions. Thus, in accordance with the obtained data, the developing of universal experimental model for the calculation of magneto-mechanical forces mediated by MNPs in low-frequency AMF was performed. The developed experimental model allows us to predict the biochemical effect of the mechanical action of MNPs with known parameters on biological macromolecules and cells in order to achieve a controlled biological effect.
ACKNOWLEDGEMENTS: The reported study was funded by RFBR according to the research project № 19-03-00738.

In recent years, more and more attention has been paid to the green chemistry in the production of nanomaterials. Therefore, the attention of many researchers is directed to the use of extracts from plants and fruits or natural compounds to obtain nanomaterials. Compounds that fulfill the requirements of green chemistry are, for example, fruit acids (alpha-hydroxy acids), naturally occurring, e.g. in fruits, almonds or wine.
The synthesis of silver nanoparticles was carried out according to the modified Lee and Meisel method in a wide pH range (from 2 to 11) using citric acid and malic acid. Keeping the same reaction conditions as the concentration of acid and silver ions, temperature, heating time, it was helpful to determine the relationship between the reaction pH, the type of acid and the size of the silver nanoparticles formed and their properties.
Colloids were analysed by UV-Vis spectroscopy and investigated by means of Transmission Electron Microscope (TEM). The study showed that the obtained colloids reduced with citric acid and malic acids are stable over time for a minimum of seven weeks. We observed that reactions occurred for citric from pH 6 and for malic acids from pH 7. The average size of the quasi-spherical nanoparticles changed with pH due to increasing of reaction rate.
The work was supported by grant no. POWR.03.02.00-00-I023/17 co-financed by the European Union through the European Social Fund under the Operational Program Knowledge Education Development.

The polymerization of aniline was studied in order to determine combination of reaction conditions that would lead to nanoparticles of certain shapes and dimensions. As-prepared nanoparticles should have as highest aspect ratio as possible, meaning they should be in shapes of rods, fibers, or even sheets. Moreover particles should be of high monodispersivity. These properties can be achieved by tuning several reaction conditions, we focused mainly on: 1. Oxidazing agent; 2. Reaction temperature; 3. Reaction time; 4. Stirring; 5. Dopant.

Vitis vinifera has provably been used for centuries on the European continent. The use of its fruits for human consumption is, however, just one of many potential applications this chemically interesting plant offers. The waste from grape wine agriculture, the dried canes, which is produced twice a year, contains a lot of biochemical substances which can serve as an aid in phytofabrication of metal nanoparticles. Successful biosynthesis of metal nanoparticles appears to be an important step towards their sustainable use in the future. In this study, we explored silver nanoparticle production using Vitis vinifera canes. We also assessed the antimicrobial activity of metal nanoparticles produced using Vitis vinifera cane extract against planktonic cells of two strains of a gram-negative bacterium Pseudomonas aeruginosa. The results show that Vitis vinifera cane extract is, in fact, capable of mediating a very effective biosynthesis of silver nanoparticles and that the biosynthesized nanoparticles exhibit measurable antimicrobial activity against the planktonic cells of P. aeruginosa.