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Background: Modern medicine requires intensive research to find new diagnostic and therapeutic solutions. Recently, upconverting nanoparticles (UCNPs) doped with lanthanide ions have attracted significant attention. Methods: The efficient internalization of UCNPs by cells was confirmed, and their precise cellular localization was determined by electron microscopy and confocal studies. Results: UCNPs colocalized only with specific organelles, such as early endosomes, late endosomes and lysosomes. Furthermore, experiments with chemical inhibitors confirmed the involvement of endocytosis in UCNPs internalization and helped select several mechanisms involved in internalization. Exposure to selected UCNPs concentrations did not show significant cytotoxicity, induction of oxidative stress or ultrastructural changes in cells. Conclusion: This study suggests that UCNPs offer new diagnostic options for biomedical infrared imaging.

Iron(iii) oxide nanoparticles doped with magnesium exposed to an alternating magnetic field induced cytotoxic effects on lung cancer cells (A549).

Ca- and Ba-doped Co/MgO–La2O3 ammonia synthesis catalysts: the location, state and effect of dopants on catalyst properties.

Co supported on mixed MgO–La2O3 oxides as efficient and stable catalysts for ammonia synthesis.

Pure niobium substrates were coated using laser cladding method. Pure molybdenum, Yttria Stabilized Zirkonia (YSZ) and corundum (Al2O3) powders were used as coating materials. Coatings were deposited on specimens as seperate paths with 3÷10mm width and 40mm of length. Two different laser power 3kW and 4kW were tested during deposition. In order to assess the quality of the Mo-YSZ and Mo-Al2O3 coatings, the light microscopy, Scanning Electron Microscopy (SEM), chemical analysis (EDS) and Vickers hardness test investigation were performed. The surface roughness and wear volume were also measured. As a result of YSZ-Mo powder cladding on the Nb substrate the composite layers were obtained without cracks and porosity not exceeding 1 μm. In addition, an increase in hardness of about 450 HV0.5 was revealed. As a result of Al2O3-Mo powder cladding on the Nb substrate the composite layers with many voids and cracks were obtained for each of the cladding variants.

Synthesis of ammonia from nitrogen and hydrogen is one of the largest manmade chemical processes, with annual production reaching 170 million tons. The Haber-Bosch process is the main industrial method for producing ammonia, which proceeds at high temperatures (400-600 °C) and pressures (20-40 MPa) using an iron-based catalyst. It is thus highly desirable to develop new catalysts with sufficient activity and stability under mild conditions. In this work, we report cobalt catalysts supported on magnesium-lanthanum mixed oxide with different Co loading amounts synthesised

The electrochemical properties of metal oxides are very attractive and fascinating in general, making them a potential candidate for supercapacitor application. Vanadium oxide is of particular interest because it possesses a variety of valence states and is also cost effective with low toxicity and a wide voltage window. In the present study, vanadium oxide nanorods were synthesized using a modified sol-gel technique at low temperature. Surface morphology and crystallinity studies were carried out by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy analysis. To the best of our knowledge, the as-prepared nanorods were tested with magnesium ion based polymer gel electrolyte for the first time. The prepared supercapacitor cell exhibits high capacitance values of the order of ~ 141.8 F g

Recent advances in nanomedicine have paved the way for developing targeted drug delivery systems. Nanoscale exosomes are present in almost every body fluid and represent a novel mechanism of intercellular communication. Because of their membrane origin, they easily fuse with cells, acting as a natural delivery system and maintaining the bioactivity and immunotolerance of cells. To develop a reconstitutable exosome-based drug candidate for clinical applications, quality assurance by preserving its physical and biological properties during storage is necessary. Therefore, this study aimed to determine the best storage conditions for exosomes derived from lung cancer cells (A549). This study established that the phosphate-buffered saline buffer enriched with 25 mM trehalose is an optimal cryoprotectant for A549-derived exosomes stored at -80°C. Under these conditions, the concentration, size distribution, zeta potential, and total cargo protein levels of the preserved exosomes remained constant.

The quantum anomalous Hall effect1,2 is a fundamental transport response of a topological insulator in zero magnetic field. Its physical origin is a result of an intrinsically inverted electronic band structure and ferromagnetism3, and its most important manifestation is the dissipationless flow of chiral charge currents at the edges of the system4, a property that has the potential to transform future quantum electronics5,6. Here, we report a Berry-curvature-driven4,7 anomalous Hall regime at temperatures of several Kelvin in the magnetic topological bulk crystals in which Mn ions self-organize into a period-ordered MnBi2Te4/Bi2Te3 superlattice. Robust ferromagnetism of the MnBi2Te4 monolayers opens a surface gap8–10, and when the Fermi level is tuned to be within this gap, the anomalous Hall conductance reaches an e2/h quantization plateau, which is a clear indication of chiral transport through the edge states. The quantization in this regime is not obstructed by the bulk conduction channels and therefore should be present in a broad family of topological magnets. A three-dimensional topological magnetic superlattice structure exhibits the quantum anomalous Hall effect when the Fermi energy is tuned into the correct energy window.

Magnetic nanoparticles of Fe3O4 doped by different amounts of Y3+ (0, 0.1, 1, and 10%) ions were designed to obtain maximum heating efficiency in magnetic hyperthermia for cancer treatment. Single-phase formation was evident by X-ray diffraction measurements. An improved magnetization value was obtained for the Fe3O4 sample with 1% Y3+ doping. The specific absorption rate (SAR) and intrinsic loss of power (ILP) values for prepared colloids were obtained in water. The best results were estimated for Fe3O4 with 0.1% Y3+ ions (SAR = 194 W/g and ILP = 1.85 nHm2/kg for a magnetic field of 16 kA/m with the frequency of 413 kHz). The excellent biocompatibility with low cell cytotoxicity of Fe3O4:Y nanoparticles was observed. Immediately after magnetic hyperthermia treatment with Fe3O4:0.1%Y, a decrease in 4T1 cells’ viability was observed (77% for 35 μg/mL and 68% for 100 μg/mL). These results suggest that nanoparticles of Fe3O4 doped by Y3+ ions are suitable for biomedical applications, especially for hyperthermia treatment.

In this paper, we present a comparative analysis of the optical properties of non-polar and polar GaN/AlGaN multi-quantum well (MQW) structures by time-resolved photoluminescence (TRPL) and pressure-dependent studies. The lack of internal electric fields across the non-polar structures results in an improved electron and hole wavefunction overlap with respect to the polar structures. Therefore, the radiative recombination presents shorter decay times, independent of the well width. On the contrary, the presence of electric fields in the polar structures reduces the emission energy and the wavefunction overlap, which leads to a strong decrease in the recombination rate when increasing the well width. Taking into account the different energy dependences of radiative recombination in non-polar and polar structures of the same geometry, and assuming that non-radiative processes are energy independent, we attempted to explain the ‘S-shape’ behavior of the PL energy observed in polar GaN/AlGaN QWs, and its absence in non-polar structures. This approach has been applied previously to InGaN/GaN structures, showing that the interplay of radiative and non-radiative recombination processes can justify the ‘S-shape’ in polar InGaN/GaN MQWs. Our results show that the differences in the energy dependences of radiative and non-radiative recombination processes cannot explain the ‘S-shape’ behavior by itself, and localization effects due to the QW width fluctuation are also important. Additionally, the influence of the electric field on the pressure behavior of the investigated structures was studied, revealing different pressure dependences of the PL energy in non-polar and polar MQWs. Non-polar MQWs generally follow the pressure dependence of the GaN bandgap. In contrast, the pressure coefficients of the PL energy in polar QWs are highly reduced with respect to those of the bulk GaN, which is due to the hydrostatic-pressure-induced increase in the piezoelectric field in quantum structures and the nonlinear behavior of the piezoelectric constant.

Composite, helical nanostructures formed using cooperative interactions of liquid crystals and Au nanoparticles were studied using a scanning transmission electron microscopy (STEM) mode. The investigated helical assemblies exhibit long-range hierarchical order across length scales, as a result of the crystallization (freezing) directed growth mechanism of nanoparticle-coated twisted nanoribbons and their ability to form organized bundles. Here, STEM methods were used to reproduce the 3D structure of the Au nanoparticle double helix.

One of the potential implementation of mesoporous silica nanomaterials (MSNs) is their use in biomedical applications as adsorbents or carriers of various bioactive substances. In this study, we attempted to fabricate silica nanomaterials containing copper and silver that were introduced into the MSN matrix, for the first time using oxalate compounds as a metal source. The syntheses were carried out using hydrothermal and impregnation methods. Structure studies revealed that the obtained nanoparticles were of a spheroidal shape and most had diameters in the range 200–500 nm. Silver and copper were found to be grouped into clusters in most samples, except in copper-decorated MSNs prepared with the impregnation method, which had an even distribution of metal atoms throughout the volume of the granule. An evaluation of the cytotoxic and irritating effects revealed that the preferred candidates for potential future applications in medicine or cosmetology among materials obtained with the presented method are the copper-conjugated MSNs.

Computed tomography (CT) of aluminum welded joint specimen has been performed. On the tomographic cross sections some defects have been found. To verify them the metallography cross sections of welded has been done. It was found that selected defects are micro cracks.

Topological insulators (TI) belong to category of phases which go beyond the theory of spontaneous symmetry breaking, well describing classical phases. TI are materials of strong spin-orbit interaction that leads to the inversed band structure. Thus, they belong to different topological class than surrounding “normal” world. Consequently, these materials behave as insulators in their volume while their surface hosts metallic states, that appear as a result of the need to meet boundary conditions. The metallic states have the unusual spin structure described by the Dirac-type Hamiltonian, with the electron spin locked to its momentum. They are protected by the time reversal symmetry, thus are resistant to non-magnetic disturbances. Introducing magnetic impurities breaks the time reversal symmetry, opening the energy gap at the Dirac point and eventually modifying spin texture. In research of magnetically doped TI there are still many challenges and open questions. Here, I will present results of our recent studies of three-dimensional TI from the Bi2-xSbxTe3-ySey family, doped with Mn ions. I will discuss possible locations of Mn impurity in the crystal host lattice, the influence of doping on the crystal structure and magnetic properties. Ferromagnetism was successfully obtained in Bi2Te3 and BiSbTe3 doped with 1.5-2 at. % of Mn, with the Curie temperature of the order of ~ 15 K. The role of free carriers in ferromagnetic interactions is not clear. Ferromagnetism is observed at diluted Mn concentrations suggesting a need for a medium mediating the long-range ferromagnetic order, but the Tc does not scale with the concentration of free carriers. We would like to acknowledge National Science Center, Poland, grant no 2016/21/B/ST3/02565.

MnBi$_{2}$Te$_{4}/$(Bi$_{2}$Te$_{3}$)$_{n}$ materials system has recently generated strong interest as a natural platform for realization of the quantum anomalous Hall (QAH) state. The system is magnetically much better ordered than substitutionally doped materials, however, the detrimental effects of certain disorders are becoming increasingly acknowledged. Here, from compiling structural, compositional, and magnetic metrics of disorder in ferromagnetic MnBi$_{2}$Te$_{4}/$(Bi$_{2}$Te$_{3}$)$_{n}$ it is found that migration of Mn between MnBi$_{2}$T$e_{4}$ septuple layers (SLs) and otherwise non-magnetic Bi$_{2}$Te$_{3}$ quintuple layers (QLs) has systemic consequences - it induces ferromagnetic coupling of Mn-depleted SLs with Mn-doped QLs, seen in ferromagnetic resonance as an acoustic and optical resonance mode of the two coupled spin subsystems. Even for a large SL separation (n $\gtrsim$ 4 QLs) the structure cannot be considered as a stack of uncoupled two-dimensional layers. Angle-resolved photoemission spectroscopy and density functional theory studies show that Mn disorder within an SL causes delocalization of electron wavefunctions and a change of the surface bandstructure as compared to the ideal MnBi$_{2}$Te$_{4}/$(Bi$_{2}$Te$_{3}$)$_{n}$. These findings highlight the critical importance of inter- and intra-SL disorder towards achieving new QAH platforms as well as exploring novel axion physics in intrinsic topological magnets., Comment: 16 pages, 5 figures, corrected typos, corrected references to figures for section 5

Gd

The paramagnetic Y

Coupling of quantum emitters in a semiconductor relies, generally, on short-range dipole-dipole or electronic exchange type interactions. Consistently, energy transfer between exciton states, that is, electron-hole pairs bound by Coulomb interaction, is limited to distances of the order of 10~nm. Here, we demonstrate polariton-mediated coupling and energy transfer between excitonic states over a distance exceeding 2~$\mu$m. We accomplish this by coupling quantum well-confined excitons through the delocalized mode of two coupled optical microcavities. Use of magnetically doped quantum wells enables us to tune the confined exciton energy by the magnetic field and in this way to control the spatial direction of the transfer. Such controlled, long-distance interaction between coherently coupled quantum emitters opens possibilities of a scalable implementation of quantum networks and quantum simulators based on solid-state, multi-cavity systems., Comment: 4 figures

This paper gives a brief summary of the Institute of Aviation's activities in space technology. Review of historical achievements and latest developments are described. Scope of present work of Space Technology Center and key projects are discussed, that include rocket and satellite technologies. Importance of space technologies in Institute of Aviation's development strategy and their crucial role for safety and independence of the state is underlined. Possibilities and future use of the developed technologies are pointed out.

Perovskites, garnets, monoclinic forms, and lately also oxyhydroxides doped with rare-earth ions have been drawn large attention due to their beneficial optical and photovoltaic properties. In this work, we have shown that several forms of crystals from Y–Al–O family can be synthesized using microwave driven hydrothermal technique using different pH and post-growth annealing at different temperatures. The structural and optical properties of these crystals were investigated as a function of hydrothermal crystallization conditions. For this purpose, x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, transmission electron microscopy, photoluminescence, and photoluminescence excitation studies were performed. All the structures have been doped with Eu3+ ions which are known as a local symmetry sensor because various symmetries generate different crystal fields and thus affect their luminescence spectra. The optical properties of the obtained nanoparticles in correlation with their structure and chemical composition are discussed.

In this work we adapt rare-earth-ion-doped NaYF4 nanoparticles coated with a silicon oxide shell (NaYF4:20%Yb,0.2%Tm@SiO2) for biological and medical applications (for example, imaging of cancer cells and therapy at the nano level). The wide upconversion emission range under 980 nm excitation allows one to use the nanoparticles for cancer cell (4T1) photodynamic therapy (PDT) without a photosensitizer. The reactive oxygen species (ROS) are generated by Tm/Yb ion upconversion emission (blue and UV light). The in vitro PDT was tested on 4T1 cells incubated with NaYF4:20%Yb,0.2%Tm@SiO2 nanoparticles and irradiated with NIR light. After 24 h, cell viability decreased to below 10%, demonstrating very good treatment efficiency. High modification susceptibility of the SiO2 shell allows for attachment of biological molecules (specific antibodies). In this work we attached the anti-human IgG antibody to silane-PEG-NHS-modified NaYF4:20%Yb,0.2%Tm@SiO2 nanoparticles and a specifically marked membrane model by bio-conjugation. Thus, it was possible to perform a selective search (a high-quality optical method with a very low-level organic background) and eventually damage the targeted cancer cells. The study focuses on therapeutic properties of NaYF4:20%Yb,0.2%Tm@SiO2 nanoparticles and demonstrates, upon biological functionalization, their potential for targeted therapy.

This paper presents the development of indigenous hybrid rocket technology, using 98% hydrogen peroxide as an oxidizer. Consecutive steps are presented, which started with interest in hydrogen peroxide and the development of technology to obtain High Test Peroxide, finally allowing concentrations of up to 99.99% to be obtained in-house. Hydrogen peroxide of 98% concentration (mass-wise) was selected as the workhorse for further space propulsion and space transportation developments. Over the course nearly 10 years of the technology’s evolution, the Lukasiewicz Research Network—Institute of Aviation completed hundreds of subscale hybrid rocket motor and component tests. In 2017, the Institute presented the first vehicle in the world to have demonstrated in-flight utilization for 98% hydrogen peroxide. This was achieved by the ILR-33 AMBER suborbital rocket, which utilizes a hybrid rocket propulsion as the main stage. Since then, three successful consecutive flights of the vehicle have been performed, and flights to the Von Karman Line are planned. The hybrid rocket technology developments are described. Advances in hybrid fuel technology are shown, including the testing of fuel grains. Theoretical studies and sizing of hybrid propulsion systems for spacecraft, sounding rockets and small launch vehicles have been performed, and planned further developments are discussed.

This study describes the facile synthesis of ZnO nanolayers by the sol-gel process and evaluates their subsequent surface passivation with ZnS by gas-phase sulfidation. The ZnO nanolayers were formed by a spin-coating technique following calcination in air in the temperature range 500–900 °C to obtain a polycrystalline wurtzite structure of ZnO. The layer thickness was optimized by adjusting the spin-coating speed and concentration of polymer in the starting solution. The continuity and formation of the films was influenced by ZnO crystal size, which was found to increase with increasing calcination temperature. The ZnO nanostructure was covered by a thin ZnS layer in a one-step passivation process carried out at room temperature in the presence of H 2 S. This thin coating of ZnS was found to have a sphalerite structure. The cathodoluminescence intensity of near-band-gap emission of the coated crystal was one order of magnitude greater following the passivation of surface defects.

Water-soluble upconversion nanoparticles (UCNPs), based on polyvinylpyrrolidone (PVP)-coated NaYF4:Er3+,Yb3+,Gd3+, with various concentrations of Gd3+ ions and relatively high upconversion efficiencies, were synthesized. The internalization and cytotoxicity of the thus obtained UCNPs were evaluated in three cell lines (HeLa, HEK293 and astrocytes). No cytotoxicity was observed even at concentrations of UCNPs up to 50 μg ml-1. The fate of the UCNPs within the cells was studied by examining their upconversion emission spectra with confocal microscopy and confirming these observations with transmission electron microscopy. It was found that the cellular uptake of the UCNPs occurred primarily by clathrin-mediated endocytosis, whereas they were secreted from the cells via lysosomal exocytosis. The results of this study, focused on the mechanisms of the cellular uptake, localization and secretion of UCNPs, demonstrate, for the first time, the co-localization of UCNPs within discrete cell organelles.

Electron paramagnetic resonance was used to investigate Mn impurity in Bi 2 Se 3 topological insulator grown by the vertical Bridgman method. Mn in high-spin S =5/2, Mn 2+ , configuration was detected regardless of the conductivity type of the host material. This means that Mn 2+ (d 5 ) energy level is located within the valence band, and Mn 1+ (d 6 ) energy level is outside the energy gap of Bi 2 Se 3 . The electron paramagnetic resonance spectrum of Mn 2+ in Bi 2 Se 3 is characterized by the isotropic g-factor | g |=1.91 and large axial parameter D =−4.20 GHz h. This corresponds to the zero-field splitting of the Kramers doublets equal to 8.4 GHz h and 16.8 GHz h, respectively, which is comparable to the Zeeman splitting for the X-band. Mn in Bi 2 Se 3 acts as an acceptor, effectively reducing native-high electron concentration, compensating selenium vacancies, and resulting in p-type conductivity. However, Mn-doping simultaneously favors formation of native donor defects, most probably selenium vacancies. For high Mn-doping it may lead to the resultant n-type conductivity related with strong non-stoichiometry and degradation of the crystal structure - switching from Bi 2 Se 3 to BiSe phase.

Sono- and photochemical reactions were combined in the synthesis of Pd-Fe- and Pt-Fe-doped titania-based photocatalysts supported on zeolite Y. In the applied procedure, no harmful reducing agents were used. The resulting photocatalysts were characterized using diffuse reflectance UV–vis spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), N 2 physisorption and inductively coupled plasma mass spectrometry (ICP-MS) techniques. The applied methodology leads to the formation of a mainly metallic form of platinum and oxidized forms of palladium and iron, with respect to different reduction potentials of metals. The photocatalytic degradation of phenol under UV light was applied as a test reaction. The photocatalyst containing Pt-Fe showed better results in this reaction in comparison with the Pd-Fe material, mainly because of the presence of the metallic form of platinum.

The use of plasmonic inclusions in heterojunction solar cells promises increase of solar-to-electric energy conversion efficiency. Recently, solar cells with ZnO nanorods attracted a lot of attention due to improved efficiency provided by highly scattering ZnO nanostructures on silicon or perovskite. N-type ZnO nanorods are grown on p-Si monocrystalline 180 μm thick substrates among others by means of a hydrothermal technique which requires prior seeding by deposition of thin film of ZnO or noble metals. In the latter case, naturally formed metal islands can also act as plasmonic nanoparticles (NPs). Excitation of plasmonic resonance on the NPs leads to directional scattering of light towards Si layer and electromagnetic field enhancement at their vicinity, close to the ZnO-Si junction, what results in improved energy absorption in the semiconductor layer and thus energy conversion efficiency. In this study, we investigate optimal conditions at which plasmonic phenomenon further improves light trapping in the Si-ZnO solar cells. In simulations performed by means of 3D FDTD method, we calculate light absorption enhancement in the system due to plasmonic NPs used as a seed layer at the ZnO/Si. In the calculations Ag, and Al NPs of different size and geometry close to that achievable in the experiment are analyzed. Finally, numerical results taking into account the granulometry of metal NPs achieved in the experiment are compared with the efficiency of fabricated cells.

Lasing relies on light amplification in the active medium of an optical resonator. There are three lasing regimes in the emission from a quantum well coupled to a semiconductor microcavity. Polariton lasing in the strong light–matter coupling regime arises from the stimulated scattering of exciton-polaritons. Photon lasing in the weak coupling regime relies on either of two mechanisms: the stimulated recombination of excitons, or of an electron–hole plasma. So far, only one or two out of these three regimes have been reported for a given structure, independently of the material system studied. Here, we report on all three lasing regimes and provide evidence for a three-threshold behavior in the emission from a photonic trap in a Se/Te-based planar microcavity comprising a single CdSe/(Cd,Mg)Se quantum well. Our work establishes the so far unsettled relation between lasing regimes that differ by their light-matter coupling strength and degree of electron–hole Coulomb correlation. Semiconductor microcavities coupled to a quantum well can produce three regimes of coherent light generation depending on the nature of the light–matter and electron–hole interactions. The authors design a Se/Te based microcavity containing a single quantum well which enables them to achieve all three lasing regimes in the one device.

Gd2O3:1% Er3+, 18% Yb3+, x% Mg2+ (x = 0; 2.5; 4; 5; 6; 8;10; 20; 25; 50) and Gd2O3:1% Er3+, 18% Yb3+, 2,5% Mg2+, y% Li+ (y = 0.5–2.5) nanoparticles were synthesized by homogenous precipitation method and calcined at 900 °C for 3 h in air atmosphere. Powder x-ray diffraction, scanning electron microscopy, cathodoluminescence, transmission electron microscopy, energy dispersive x-ray spectroscopy and photoluminescence techniques were employed to characterize the obtained nanoparticles. We observed a 8-fold increase in red luminescence for samples suspended in DMSO solution for 2.5% of Mg2+ doping. The x-ray analysis shows that for the concentration of 2.5% Mg, the size of the crystallites in the NPs is the largest, which is mainly responsible for the increase in the intensity of the upconversion luminescence. But the addition of Li+ ions did not improve the luminescence of the upconversion due to decreasing of crystallites size of the NPs. Synthesized nanomaterials with very effective upconverting luminescence, can act as luminescent markers in in vivo imaging. The cytotoxicity of the nanoparticles was evaluated on the 4T1 cell line for the first time.

The effect of the ZnO nanoparticles (NPs) size on the photocatalytic degradation of phenol in a water solution under the influence of UV and Vis radiation was discussed. For the first time, research on photocatalytic degradation has used ZnO NPs produced by only one method (microwave solvothermal synthesis without heat treatment or other processes of reduction/oxidisation of the surface of NPs samples). ZnO NPs average size was determined using the Scherrer's formula, Nanopowder XRD Processor Demo web application, by converting the results of the specific surface area-density, and TEM tests. The ZnO NPs (average size between 23 nm and 71 nm) characterise by uniform morphology and narrow size distribution. The photocatalytic performance of ZnO NPs increases with the increase of the particle size and the decrease of the specific surface area. For both UV and Vis radiation, the highest reaction rate for phenol degradation was found for ZnO sample with the average particle size of 71 nm. Low concentrations of resorcine and hydroquinone (co-products of phenol degradation) were found for UV light photocatalytic test. However, high concentrations of hydro- and p-benzoquinone were observed for visible light photoactivity due to the slower decomposition of the main contamination associated with the utilized of other type of radiation. The photocatalytic activity was found to be attributable to the decrease in the charge carrier recombination rate.

The structural, electronic, and magnetic properties of low-energy rhenium implanted c-Si are examined for the first time. The damage created by rhenium ions and the following partial reconstruction of the silicon host matrix after rapid thermal annealing (RTA) are investigated as a function of the fluence. Rutherford backscattering spectrometry (RBS) results reveal that the implanted ions are located in the near-surface region with the distribution maximum at about 23 nm below the surface. The analysis of rhenium-depth distribution using the McChasy code shows that the implanted Re-ions are located in the interstitial lattice positions. The RTA leads to a partial recovery of the silicon crystal structure. According to the RBS results, the formed inclusions are not coherent with the silicon host matrix causing an increase of the lattice distortion. Analysis of channeled RBS/c spectra carried out by the McChasy code revealed different levels of bent channels in damaged regions suggesting bimodal distribution of inclusions in the silicon. Studies of high-resolution X-ray photoelectron spectroscopy (XPS) conducted after the RTA showed the shift of Re 4f7/2 binding energy (BE) by +0.68 and + 0.85 eV with respect to metallic rhenium for the samples with lower/higher fluencies, respectively. Complex XPS, density functional theory (DFT) simulations, and transmission electron microscopy (TEM) data analysis allowed us to conclude that the near-surface layer of the sample (∼10 nm) consists of nanoinclusions with cubic and/or hexagonal ReSi. In the middle area of the samples, much larger nanoinclusions (>10/20 nm for higher/lower fluencies, respectively) containing pure metallic rhenium inside are formed. The RTA increases the magnetic moment of the sample with the lower dose nearly 20-fold, whereas in the sample with the higher dose a 3-fold increment is observed only. The magnetic response of the examined systems after the RTA indicates a presence of magnetic interactions between the nanoinclusions resulting in the system exhibiting super-spin glass or super-ferromagnetism.

In photodynamic therapy (PDT), photosensitizer (PS) molecules are irradiated by light to generate reactive oxygen species (ROS), the presence of which subsequently leads to cell death. At present, the modality is limited to the treatment of skin diseases because of the low tissue penetration of visible or ultraviolet light required for producing ROS. To increase tissue penetration and extend the therapeutic possibilities of PDT to the treatment of deep-seated cancer, rare-earth doped nanoparticles capable of up-converting infrared to visible light are investigated. These up-converting nanoparticles (UCNPs) are conjugated with PS molecules to efficiently generate ROS. In this work, we employ hexagonal β-NaYF4:Yb3 + ,Er3 + as UCNPs and Rose Bengal (RB) as PS molecules and demonstrate efficient in vitro PDT using this nanoformulation. Covalent bonding of the RB molecules is accomplished without their functionalization-an approach which is expected to increase the efficiency of ROS generation by 30%. Spectroscopic studies reveal that our approach results in UCNP surface fully covered with RB molecules. The energy transfer from UCNPs to RB is predominantly non-radiative as evidenced by luminescence lifetime measurements. As a result, ROS are generated as efficiently as under visible light illumination. The in vitro PDT is tested on murine breast 4T1 cancer cells incubated with 250 µg ml-1 of the nanoparticles and irradiated with NIR light under power density of 2 W cm-2 for 10 minutes. After 24 hours, the cell viability decreased to 33% demonstrating a very good treatment efficiency. These results are expected to simplify the protocols for preparation of the PDT agents and lead to improved therapeutic effects.

Commercial TiO2 (P25), alone or in the presence of graphite oxide (GO), was exposed to ultrasound treatment (US) with the objective to modify the surface of nanoparticles through introducing defects and chemical heterogeneity, and to build the composite with GO of synergistic features. The obtained materials were extensively characterized using XRD, HR-TEM, TA-MS, FTIR, XPS, potentiometric titration, adsorption of nitrogen, and UV/Vis diffuse reflectance techniques. The results showed that the US treatment/activation led to the formation of defects on the surface of the TiO2 nanoparticles, which were associated with an increase in the amount of terminal hydroxy groups, and which resulted in narrowing of the band gap energy. The composite formed upon the ultrasonic activation contained partially reduced GO particles deposited on the surface of TiO2 aggregates and bonded with the titania phase through its carboxylic groups existing at the edges of small defectous graphene particles, leading to a high volume of mesopores formed between the particles/aggregates of the nanoparticles. The US-treated materials showed a superior bifunctional detoxification performance, to adsorb and photocatalytically decompose vapors of a chemical warfare agent surrogate, as a result of the surface alteration/activation and an increase in the porosity.

We report on the binding energy of a charged exciton (trion) confined in a single, epitaxially grown 1.7 nm thick ZnO/(Zn,Mg)O quantum well as large as 22 meV or 27.6 meV when determined in micro-photoluminescence or transmission measurements, respectively. Charged exciton emission is found to persist up to near room temperature. The binding energy comparable to thermal energy at room temperature is promising for trion based spintronic and optoelectronic applications.