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Vol 14, No 5-6 (2019)
- Year: 2019
- Articles: 12
- URL: https://journals.rcsi.science/2635-1676/issue/view/13666
Self-Assembled Structures and Nanoassemblies
Zn1 – xCdxS Nanoparticles Obtained by Laser Ablation
Abstract
Approximately spherical nanoparticles of the II–VI semiconductor materials Zn1 – xCdxS have been produced successfully by laser ablation of the bulk material in several liquids. The non-stabilized suspensions of particles are characterized by absorption spectroscopy and transmission electron microscopy (TEM). The procedure is not strongly size-selective, radii of 7 ± 3 nm were found for Zn1 – xCdxS by transmission electron microscopy. Acetonitrile stabilizes the particles for several days up to weeks. Prolonged irradiation leads effectively to a reduction in particles size, in which particle agglomeration may play an important role. Ablation in degassed liquids does not have a significant effect on the absorption of the suspended particles.
185-189
Functional and Construction Nanomaterials
High Photocatalytic Activity Nanomaterials Based on Titanium Dioxide
Abstract
Abstract—X-ray diffraction, optical spectroscopy, and electron paramagnetic resonance (EPR) have been used to study microspheres and nanoheterostructures based on titanium dioxide synthesized by aerosol pyrolysis and sol–gel methods. All test samples are characterized by a large specific surface area (about 100 m2/g of substance). It was established that the main type of radicals in the resulting structures are N•, NO•, as well as Ti3+, Mo5+, V4+, and W5+ centers. Microspheres and nanoheterostructures consisting of several metal oxides have high photocatalytic activity in the visible spectrum and the ability to accumulate photogenerated charge carriers. As a result, catalytic reactions in the samples continue even after illumination is turned off. A correlation was found between the rate of photocatalysis and the radical concentration in the studied structures. The results can be used to develop new-generation energy-efficient catalytic devices based on nanocrystalline titanium oxide, which operate in the visible range and do not require continuous illumination.
190-196
Nano- and Microstructures with Equal Zero Ohmic Losses in a Spontaneously Polarized State
Abstract
Abstract—Structures with zero ohmic resistance for a constant and sinusoidal electric current are obtained. As in the case of superconductivity, this effect is due to the exchange–correlation interaction of electrons, but for a different reason: polarization of the structure by an electric field, and not Cooper-pair polarization of the lattice.
197-203
Stabilized Titanium Dioxide Nanoparticles: Preparation and Physicochemical, Photocatalytic, and Antimicrobial Properties
Abstract
The anatase nanoparticles are stabilized with titanium tetraisopropoxide Ti[OCH(CH3)2]4 and isopropyl alcohol without surfactants suitable for biological studies. We showed that the hydrodynamic radii in suspensions depend on temperature and the duration of hydrolysis, whereas the composition (a mixture of anatase with brookite, anatase, brookite, and rutile) and the sizes of crystallites (X-ray), nanoparticles, and aggregates (SEM) in the dried state are mainly dependent on the pH of the environment. The nonphase of the samples stems from coherent intergrowth of unit cells of anatase and brookite via geometric and structural complementarity. We found that photocatalytic activity (PCA; Rhodamine 6G model dye under UV radiation) depends on OH/H2O ratio (adsorbed), whereas antimicrobial activity (AMA) in the dark depends on an amount of free water on the surface of nanoparticles according to X-ray photoelectron spectroscopy (XPS). We revealed that samples with the smallest sizes of nanoparticles of all levels possess the highest PCA and AMA relative to Staphylococcus aureus and Escherichia coli.
204-215
Study of the Influence of Silicon Dioxide Nanoparticles on the Surface Properties of Silicon Organic Coatings
Abstract
Abstract—Coatings are made using SKTN-f methylphenylsiloxane rubber with different contents of PMS-200 polymethylsiloxane oil and BS-100 white carbon nanoparticles. The authors studied the abrasion resistance and hydrophobic properties (wetting angle, roll-off angle) of coatings and ice adhesion to their surfaces. It is shown that the introduction of polymethylsiloxane oil into the polymer matrix decreases abrasion resistance and hydrophobic properties of the coatings, while at the same time reducing surface ice adhesion. It was established that the introduction of BS-100 nanoparticles can increase the physicomechanical characteristics of coatings while maintaining the level of functional properties. The obtained results for the dependence of functional properties on the chemical composition of the coatings are explained by their structural features; in particular, polymethylsiloxane oil is evenly distributed over the bulk of the polymer matrix, enveloping agglomerates of white carbon nanoparticles emerging on the surface, thereby forming a multimodal roughness, which in turn increases the hydrophobic properties of coatings.
216-221
Low-Temperature Degradation of Composite ATZ Ceramics Reinforced via Multiwalled Carbon Nanotubes
Abstract
The influence of water vapor on structural stability and mechanical properties of ceramics based on baddeleite (natural zirconia mineral) and chemically deposited ZrO2 reinforced with carbon nanotubes is studied in this work. These composites are shown to possess high physical and mechanical properties and elevated hydrothermal aging resistance. Composites based on baddeleite and stabilized СаО are characterized via ageing rate of an order of magnitude lower than in the case of commercial ceramics stabilized with Y2О3. The embedding of carbon nanotubes in the composites and the use of spark plasma sintering inhibits the grain growth and amplifies the scale effect in hardness. With that, crack resistance KC under hydrothermal conditions decreases to a lesser extent than in nanotube-free composites.
222-233
Research of the Possibility to Obtain Structures with Nanometer Layer Thicknesses and Sharp-Cut Interfaces between Them Using Ion-Beam and Reactive Ion-Beam Deposition Processes
Abstract
Abstract—At present, atomic layer deposition and magnetron sputtering processes are used in the production of integrated circuits (IC) to obtain structures with nanometer layer thicknesses and sharp interfaces between them. However, there are also ion-beam and reactive ion-beam deposition processes, which are mainly used to produce multilayer optical coatings. The aim of this work is to study the possibility of obtaining structures with nanometer layer thicknesses and sharp interfaces between them in the processes of ion-beam and reactive ion-beam deposition. The studies were carried out by time-of-flight secondary ion mass spectrometry (SIMS) and spectral ellipsometry methods. Study of the structure Ta (3 nm)/Nb (3 nm)/Ta (3 nm) reveals that ion-beam deposition can form structures with nanometer layer thicknesses and sharp boundaries between them. On the other hand, in reactive ion-beam deposition of the structure Nb (3 nm)/Ta2O5 (3 nm)/Nb (3 nm), oxidation occurs on the entire thickness of the metal layer following the metal oxide layer due to ions, atoms, and molecules of oxygen contained in the ion beam.
234-239
Polymer, Bioorganic, and Hybrid Nanomaterials
Effect of Nanographite Type on Structure and Mechanical Properties of Hybrid Composites of Poly(ethylene terephthalate) Filled with Short Glass Fibers and Nanographite
Abstract
Abstract—The paper presents the results of comparative studies of the structure and rheological and strength properties of poly(ethylene terephthalate) (PET) filled with hybrid micro- and nanofillers—short glass fibers (GF) and nanographite (nG) of two types—expanded graphite (EG), prepared by hydrolysis of sodium-intercalated graphite, and thermally expanded graphite (TEG), prepared by thermal shock treatment of sulfuric acid intercalated graphite in air. The GF concentration varied within 15–60 wt %, and that of nG, from 0.4 to 3 wt %. The composites were produced by reactive compounding using a corotating twin-screw extruder (screw diameter 35 mm, L/D = 40). It is established that the nG preparation method strongly influences the structure and properties of the composites. EG, unlike TEG, displays improved dispersibility in the polymer, helps to increase the proportion of GF with an average length exceeding the critical length, and reduces PET degradation, which increases the strength characteristics of PET/GF/EG hybrid composites in comparison to PET/GF/TEG at a high GF content of 45–60 wt %. The hybrid composites also demonstrate accelerated PET crystallization and a synergetic increase in the elasticity modulus.
240-247
Nanobiology and Genetics, Omics
Effect of the Presowing Treatment of Potato Tubers with Film Coating Containing Metal Nanoparticles on Pathologies and Yield Production
Abstract
A preparation based on iron, zinc, copper, and molybdenum nanoparticles (NPs) in a polymer film formed from a mixture of Na-carboxymethylcellulose and polyethylene glycol-400 was developed for presowing pretreatment of potato tubers. Based on laboratory tests, the optimal concentrations and ratio of Fe : Zn : Cu : Mo nanoparticles were determined as 10–6 : 10–2 : 10–8 : 10–8 (%). Field tests in the integrated system of potato protection showed that the presowing treatment of potato tubers with nanoparticles Fe : Zn : Cu : Mo in the polymer film reduced the prevalence and degree of development of Alternaria blight (2.2 and 2.4 times) and late blight of potato (3.4 and 4.2 times) during the growing season and led to an increase in yield of marketable products by 11.7% compared to the control.
248-254
The Biological Activity of a Selenium Nanocomposite Encapsulated in Carrageenan Macromolecules with Respect to Ring Rot Pathogenesis of Potato Plants
Abstract
The effect of selenium nanocomposite encapsulated in a carrageenan matrix (NC Se/Car) on the Clavibacter michiganensis ssp. sepedonicus (Cms) bacteria (causing potato ring rot) and potato plants has been studied. The electron microscopy data indicate that NC Se/Car comprise spherical selenium nanoparticles (of a wide size range) forming aggregates. The nanocomposite has not been found to exhibit any bacteriostatic and antibiofilm activity against Cms. Our experiments on plants have shown a stimulating effect of NC Se/Car on the plant biometric indicators and a decreased harmful effect of Cms infection. The insignificant accumulation of selenium in the potato tissues treated with NC Se/Car (0.01–0.03% of air-dry weight) has been found. These results allow us to consider NC Se/Car as a plant development stimulator for agricultural crops.
255-262
Nanobiomedicine and Nanopharmaceuticals
Composite Nanoparticles Based on the Lexan Polymer Matrix, Ytterbium Complexes of Porphyrins, and Iron Oxide for NIR Luminescent Diagnostics and Neoplasm Theranostics
Abstract
The synthesis procedure and the spectral luminescent properties of nanoparticles containing the ytterbium complex of protoporphyrin IX dimethyl ester in a Lexan-based polymer matrix, promising for application in neoplasm diagnostics, are described. Nanoparticles have an increased luminescence lifetime in the 700–1100 nm near infrared region and almost no porphyrin free base fluorescence in the red spectral region, which shows promise in using the nanoparticles for diagnostic purposes. For theranostic purposes, the synthesis of multifunctional nanoparticles with a core of iron oxides and a Lexan-polymer shell containing the ytterbium complex of hematoporphyrin IX tetramethyl ester was carried out. We assume iron oxide nanoparticles are responsible for the local hyperthermia procedure.
263-272
Preparation of stabilized silver nanoparticles and study of their antimicrobial and cytotoxic activity on the human hepatoma HepG2 cell line
Abstract
Silver nanoparticles were synthesized using arabinogalactan and sodium dioctyl sulfosuccinate to reduce and stabilize them. The average hydrodynamic size of the nanoparticles, determined by photon correlation spectroscopy, was 30 nm, and the zeta potential was –34.04 ± 1.54 mV. According to the electron diffraction method, silver in the sol sample is in metallic form. The preparation of silver nanoparticles showed antibacterial activity against opportunistic Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis and B. coagulans) bacteria. Silver nanoparticles also had antifungal activity against strains of phytopathogenic fungi of the genus Fusarium sporotrichioides and F. solani. A study of the cytotoxic activity of silver nanoparticles was made on human hepatoma cells of the HepG2 line. The inhibitory effect of silver nanoparticles on the metabolic activity and viability of tumor cells has been demonstrated. The average relative EC50 values for silver nanoparticles were 1.5 ± 0.4 μg/ml and 41.2 ± 3.9 μg/mL. The preparation of stabilized silver nanoparticles can find application in medicine, as a potential antimicrobial and antitumor agent, as well as in agriculture as a means of suppressing growth of phytopathogenic fungi.
273-279