Formation and Properties of Thermistor Chips Based on Semiconductor 3D Metal Oxide Films Obtained by RF-Magnetron Sputtering.

The formation of oxide semiconductor films of the (Mn,Co,Cu)3O4 type by radio frequency magnetron sputtering is presented. The conditions of deposition and subsequent heat treatment make it possible to obtain films with electrophysical characteristics close to those of the bulk ceramic materials used as a target for magnetron sputtering. Two variants of thermistor geometry were implemented. In the first case, the working layer of oxide semiconductor was deposited directly on the dielectric substrate (planar geometry), and in the second case on the layer with high electrical conductivity (Ni or Al) forming the inner electrode (layered geometry). The lower limit of the nominal resistance of the planar thermistor while maintaining high temperature nonlinearity is ~ 10 kΩ. The layered structure with the inner electrode makes it possible to reduce the lower limit of resistance up to ~ 50 Ω without losing the temperature nonlinearity of the thermistor. In addition, heat treatment above 450 °C or current self-heating with sufficient power output leads to the appearance of a pronounced voltage nonlinearity, which increases the thermal constant B of thermistors from 2400-3400 to 5000-5500 K. The fields of application of oxide-film structures for the correction of linear resistors and the implementation of integration approaches in the construction of linearized sensors are discussed.

Stochastic Memristive Interface for Neural Signal Processing.

We propose a memristive interface consisting of two FitzHugh-Nagumo electronic neurons connected via a metal-oxide (Au/Zr/ZrO2(Y)/TiN/Ti) memristive synaptic device. We create a hardware-software complex based on a commercial data acquisition system, which records a signal generated by a presynaptic electronic neuron and transmits it to a postsynaptic neuron through the memristive device. We demonstrate, numerically and experimentally, complex dynamics, including chaos and different types of neural synchronization. The main advantages of our system over similar devices are its simplicity and real-time performance. A change in the amplitude of the presynaptic neurogenerator leads to the potentiation of the memristive device due to the self-tuning of its parameters. This provides an adaptive modulation of the postsynaptic neuron output. The developed memristive interface, due to its stochastic nature, simulates a real synaptic connection, which is very promising for neuroprosthetic applications.

Exploring the Interplay between Drug Release and Targeting of Lipid-Like Polymer Nanoparticles Loaded with Doxorubicin.

Targeted delivery of doxorubicin still poses a challenge with regards to the quantities reaching the target site as well as the specificity of the uptake. In the present approach, two colloidal nanocarrier systems, NanoCore-6.4 and NanoCore-7.4, loaded with doxorubicin and characterized by different drug release behaviors were evaluated in vitro and in vivo. The nanoparticles utilize a specific surface design to modulate the lipid corona by attracting blood-borne apolipoproteins involved in the endogenous transport of chylomicrons across the blood-brain barrier. When applying this strategy, the fine balance between drug release and carrier accumulation is responsible for targeted delivery. Drug release experiments in an aqueous medium resulted in a difference in drug release of approximately 20%, while a 10% difference was found in human serum. This difference affected the partitioning of doxorubicin in human blood and was reflected by the outcome of the pharmacokinetic study in rats. For the fast-releasing formulation NanoCore-6.4, the AUC0→1h was significantly lower (2999.1 ng × h/mL) than the one of NanoCore-7.4 (3589.5 ng × h/mL). A compartmental analysis using the physiologically-based nanocarrier biopharmaceutics model indicated a significant difference in the release behavior and targeting capability. A fraction of approximately 7.310-7.615% of NanoCore-7.4 was available for drug targeting, while for NanoCore-6.4 only 5.740-6.057% of the injected doxorubicin was accumulated. Although the targeting capabilities indicate bioequivalent behavior, they provide evidence for the quality-by-design approach followed in formulation development.

Halobacterium salinarum storage and rehydration after spray drying and optimization of the processes for preservation of carotenoids.

Spray drying is appropriate for the preservation of halophilic microorganisms due to the nature of these microorganisms, as they survive in adverse environmental conditions by being encapsulated in salt crystals. Artificial neural networks were in this study used to optimize practically significant spray-drying regimes of the C50-carotenoids producer Halobacterium salinarum. Immediately after drying, the samples contained up to 54% halobacterial biomass and less than 5% moisture, and the level of preservation of carotenoids was 95-97%. The storage of biomass at 4 °C resulted in the gradual degradation of the carotenoids, which reached 58-64% in the best samples after 1 year. A comprehensive study of changes in halobacteria biomass after spray drying and the nature of the damage provided new data on the survival and preservation of cells and biologically active substances in the various spray-drying regimes and at different storage times.

Deep UV narrow-band photodetector based on ion beam synthesized indium oxide quantum dots in Al2O3 matrix.

Semiconductor quantum dots have attracted tremendous attention owing to their novel electrical and optical properties as a result of their size dependent quantum confinement effects. This provides the advantage of tunable wavelength detection, which is essential to realize spectrally selective photodetectors. We report on the fabrication and characterization of a high performance narrow band ultraviolet photodetector (UV-B) based on Indium oxide (In2O3) nanocrystals embedded in aluminium oxide (Al2O3) matrices. The In2O3 nanocrystals are synthesized in an Al2O3 matrix by sequential implantation of In+ and [Formula: see text] ions and post-implantation annealing. The photodetector exhibits excellent optoelectronic performances with high spectral responsivity and external quantum efficiency. The spectral response shows a band-selective nature with a full width half maximum of ∼60 nm, and a responsivity reaching up to 70 A W-1 under 290 nm at 5 V bias. The corresponding rejection ratio to visible region was as high as 8400. The high performance of this photodetector makes it highly suitable for practical applications such as narrow-band spectrum-selective photodetectors. The device design based on ion-synthesized nanocrystals could provide a new approach for realizing a visible-blind photodetector.

Effect of Post-Implantation Heat Treatment Conditions on Photoluminescent Properties of Ion-Synthesized Gallium Oxide Nanocrystals.

A novel and promising way for creating nanomaterials based on gallium oxide is the ion synthesis of Ga2O3 nanocrystals in a SiO2/Si dielectric matrix. The properties of nanocrystals are determined by the conditions of ion synthesis-the parameters of ion irradiation and post-implantation heat treatment. In this work, the light-emitting properties of Ga2O3 nanocrystals were studied depending on the temperature and annealing atmosphere. It was found that annealing at a temperature of 900 °C leads to the appearance of intense luminescence with a maximum at ~480 nm caused by the recombination of donor-acceptor pairs. An increase in luminescence intensity upon annealing in an oxidizing atmosphere is shown. Based on data from photoluminescence excitation spectroscopy and high-resolution transmission electron microscopy, a hypothesis about the possibility of the participation of a quantum-size effect during radiative recombination is proposed. A mechanism for the formation of Ga2O3 nanocrystals during ion synthesis is suggested, which makes it possible to describe the change in the luminescent properties of the synthesized samples with varying conditions of post-implantation heat treatment.

Structure and Chemical Composition of Ion-Synthesized Gallium Oxide Nanocrystals in Dielectric Matrices.

The ion-beam synthesis of Ga2O3 nanocrystals in dielectric matrices on silicon is a novel and promising way for creating nanomaterials based on gallium oxide. This research studies the regularities of changes, depending on the synthesis regimes used, in the chemical composition of ion-implanted SiO2/Si and Al2O3/Si samples. It has been shown that the formation of Ga-O chemical bonds occurs even in the absence of thermal annealing. We also found the conditions of ion irradiation and annealing at which the content of oxidized gallium in the stochiometric state of Ga2O3 exceeds 90%. For this structure, the formation of Ga2O3 nanocrystalline inclusions was confirmed by transmission electron microscopy.

Electrical Characteristics of CMOS-Compatible SiOx-Based Resistive-Switching Devices.

The electrical characteristics and resistive switching properties of memristive devices have been studied in a wide temperature range. The insulator and electrode materials of these devices (silicon oxide and titanium nitride, respectively) are fully compatible with conventional complementary metal-oxide-semiconductor (CMOS) fabrication processes. Silicon oxide is also obtained through the low-temperature chemical vapor deposition method. It is revealed that the as-fabricated devices do not require electroforming but their resistance state cannot be stored before thermal treatment. After the thermal treatment, the devices exhibit bipolar-type resistive switching with synaptic behavior. The conduction mechanisms in the device stack are associated with the effect of traps in the insulator, which form filaments in the places where the electric field is concentrated. The filaments shortcut the capacitance of the stack to different degrees in the high-resistance state (HRS) and in the low-resistance state (LRS). As a result, the electron transport possesses an activation nature with relatively low values of activation energy in an HRS. On the contrary, Ohm's law and tunneling are observed in an LRS. CMOS-compatible materials and low-temperature fabrication techniques enable the easy integration of the studied resistive-switching devices with traditional analog-digital circuits to implement new-generation hardware neuromorphic systems.

Ion-Beam Synthesis of Gallium Oxide Nanocrystals in a SiO2/Si Dielectric Matrix.

A new method for creating nanomaterials based on gallium oxide by ion-beam synthesis of nanocrystals of this compound in a SiO2/Si dielectric matrix has been proposed. The influence of the order of irradiation with ions of phase-forming elements (gallium and oxygen) on the chemical composition of implanted layers is reported. The separation of gallium profiles in the elemental and oxidized states is shown, even in the absence of post-implantation annealing. As a result of annealing, blue photoluminescence, associated with the recombination of donor-acceptor pairs (DAP) in Ga2O3 nanocrystals, appears in the spectrum. The structural characterization by transmission electron microscopy confirms the formation of ß-Ga2O3 nanocrystals. The obtained results open up the possibility of using nanocrystalline gallium oxide inclusions in traditional CMOS technology.

Antimicrobial activity of silver salt and silver nanoparticles in different forms against microorganisms of different taxonomic groups.

The development of antiseptics and medical products (bandaging materials, sponges, etc.) based on silver nanoparticles is an essential task due to the growing resistance of pathogenic microorganisms to medicines long used in clinical practice. Using silver nanoparticles for the same purpose is promising, but the potential hazards and cumulative effects in the application of nanoparticles requires a thorough study of those materials. To evaluate the efficiency of antiseptics and medical products based on silver nanoparticles, it is necessary to conduct an in-depth study of the activity of silver nanoparticles in different forms and immobilized in carriers. The study examines the resistance of bacterial and fungal cultures to silver nanoparticles produced by chemical reduction and microbiological synthesis. The study of resistance was carried out in different growth phases of pathogenic microorganisms and in both liquid and solid media. Chemically and microbiologically synthesized nanoparticles were added in the form of a suspension, as well as encapsulated in chitosan-PVA matrices. It was experimentally discovered that, depending on the medium and form of the silver, the antibacterial effect would significantly differ due to changes in the mechanisms regarding the release of nanoparticles and their activity against the cells of pathogenic and potentially pathogenic microorganisms.

Development of novel PLGA nanoparticles with co-encapsulation of docetaxel and abiraterone acetate for a highly efficient delivery into tumor cells.

Co-encapsulation of abiraterone acetate (AbrA) and docetaxel (Dtx) in polymeric nanoparticles as novel prototypes for prostate cancer treatment combining hormonal and chemotherapy was designed. Nanoparticles (NPs) composed of poly(dl-lactide-co-glycolide) (PLGA) were prepared by single-emulsion solvent evaporation technique and characterized in terms of morphology with atomic force microscopy and transmission electron microscopy. HPLC method for simultaneous determination of AbrA and Dtx encapsulation efficacy was developed. Also differential scanning calorimetry and Fourier-transform infrared spectroscopy were provided. To study the effectiveness of cellular internalization and distribution of NPs with AbrA and Dtx co-encapsulation (NP-AbrA/Dtx), a fluorescence microscopy was utilized. NPs prepared had size 256.3 ±9.4 nm and zeta potential -18.4 ±1.4 mV. Encapsulation efficacy for AbrA was 68.7% and for Dtx was 74.3%. NPs were able to control the AbrA and Dtx release within 24 h. The mathematical model of drug release was performed. The results obtained from confocal microscopy showed the effective accumulation of the NP-AbrA/Dtx in the cytoplasm of cells. Synthesized NPs possessed satisfactory parameters and a biphasic release profile, proceeding by the Fick diffusion mechanism, which provide prolonged release of the drugs and maintenance of their concentration. It was shown that NPs loaded with AbrA and Dtx exhibited a high cytotoxic activity on the LNCaP cell line, similar to the combination of free drugs of AbrA and Dtx, but in contrast to the combination of substances, had a synergistic mechanism of action. Our findings support the potential use of developed NPs in further in vivo studies. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1150-1158, 2019.