Inorganic Materials: Applied Research最新文献

Evolution of textural compositions in aluminum alloys during bending is studied. The change in crystallographic texture in billets and samples after bending of two materials is analyzed using X-ray diffraction. It is shown that bending leads to the formation of an anisotropic texture with a dominance of shear-type components. Particular attention is paid to the role of recrystallization nuclei in the reorientation of the grain structure. The relationship between texture evolution and mechanical properties of materials is also analyzed. It is experimentally established that the ductile A5 alloy is characterized by an ordered transformation of texture during bending. In contrast, in the high-strength 1565ch alloy, bending leads to texture blurring with an increase in the textureless fraction, which is due to the heterogeneity of deformation. The results of the study are of practical importance for predicting the mechanical properties of aluminum alloys after bending and optimizing the technological parameters of processing.

The paper deals with Lüders deformation in an aluminum-magnesium alloy with structural heterogeneity in the form of a friction stir weld. It is found that a complex structural state due to the weld seam causes two zones in the specimen: the base metal where Lüders deformation occurs and the stir zone where deformation does not localize. Thermomechanically affected zones with increased microhardness compared to the base metal and stir zone are sources of Lüders deformation fronts. Depending on the strain rate, deformation fronts can move intermittently or continuously. The kinetics of fronts is determined by the response of active deformable media to external mechanical action and can be described within the autowave concept of plastic deformation similarly to homogeneous materials.

Functionally organized steel-aluminum compositions were manufactured by liquid and solid phase methods, namely arc, friction surfacing, and explosion welding processes. The influence of the manufacturing process on the characteristics of the diffusion zone separating the pure aluminum functional layer and the steel substrate has been determined. It has been established that a layer of Fe_xAl_y double intermetallic compounds of different stoichiometric composition is formed between the functional layer and the substrate. It has been shown that this layer is characterized by a discrete nature and an average thickness of 16 µm in compositions manufactured by the explosion welding process. The use of arc or friction surfacing processes leads to the formation of a continuous intermetallic layer with an average thickness of 8.2 and 2 µm, respectively. The level of adhesive strength of manufactured functionally organized steel-aluminum compositions was assessed in order to determine their properties.

This work performed a detailed characterization of the chemistry of the vancomycin-loaded PLGA-CaP composite coatings with different PLGA concentrations (5, 8, 10 wt %) on titanium implants for controlled sustained drug delivery. The lower CaP layer had a complex porous morphology with numerous branched pores and pore channels, and spheroidal elements on the surface, into which the antibiotic vancomycin was effectively loaded. The upper dense homogeneous PLGA layer partially penetrated the near-surface pores with drug. A gradient elemental composition (Ca, P, Ti, O, C) along the thickness and the homogeneous elemental distribution on the surface of all the vancomycin-loaded PLGA-CaP composite coatings were revealed. The vancomycin-loaded CaP coatings included strong P–O and P–OH bonds, while the composite vancomycin-loaded PLGA-CaP coatings were characterized by –C=O, –COO and C–O–C bonds. The formation of strong chemical bonds between the drug and the carrier components was confirmed by the alterations and broadening of the C1s, O1s, Ca2p and Ti2p peaks. This may be a favorable factor for efficient controlled sustained drug delivery.

The paper proposes an innovative method for express assessment of the InGaAs/InP epitaxial structure parameters with SCAM architecture. As the result of the work, an InGaAs/InP heterostructure was grown, models for verification were developed, tests were performed to assess the characteristics of the epitaxial structure and real characteristics were compared with simulated results.

The effect of preliminary irradiation with argon ions (energy of 20 keV, dose of 2.0 × 10²² m^–2, T_irr ∼ 700 K) and subsequent exposure to pulsed laser radiation (LR) with a power density of q ∼ 1.2 × 10¹² W/m², pulse duration τ₀ = 50 ns, and the number of pulses from 1 to 4 on the morphology and microhardness of the surface of V–10Ti–6Cr–0.05Zr–0.1Si vanadium alloy is studied. It is found that implantation of Ar⁺ ions in the specified mode leads to the formation of a porous (spongy) structure in the surface layers. It is shown that, as a result of the impact of pulsed LR, a common feature of the destruction of the surface layer of both the initial sample and the sample preliminarily irradiated with argon ions is the formation of a crater surrounded by a parapet. However, in the second case, the parapet is a ring-shaped rim, and there is practically no splashing of metal out of the crater. It is found that, as a result of ultrafast melting and crystallization, a fine-cell structure with a cell size of ∼200 nm is formed in the near-surface layers of samples implanted with Ar⁺ in the region of the crater. Behind the crater, there is a heat-affected zone (HAZ), into which the plasma cloud transfers part of its energy. It is established that, as a result of the combined effect of argon ions and pulsed laser radiation, typical structures are formed in the HAZ, being observed both for this alloy and for vanadium arising under the influence of LR under various modes of preliminary ion implantation. It is found that the microhardness of the surface layers after implantation of Ar⁺ ions into alloy increases slightly. After the impact of pulsed LR on both the initial and preliminarily implanted (by Ar⁺) alloy samples, the microhardness in the crater area first decreases, and then, with an increase in the number of pulsed impacts, a tendency towards its increase is observed. The mechanisms of the observed phenomena are discussed.

The interaction between platinum (Pt) and Chlorin e6 in aqueous solutions has been studied using luminescence and electron spectroscopic techniques. The potential for singlet oxygen formation and photodegradation of Chlorin e6 in the presence of platinum under red light has been investigated. It has been found that an aqueous solution of Chlorin e6 with platinum exhibits photodynamic activity, generating singlet oxygen more intensely than a solution of Chlorin e6 alone. Effective cell death has been observed in tumor cells of the Ehrlich ascites adenocarcinoma after one day of exposure to the Chlorin e6-Pt complex. A solution with a 1 : 0.5 molar ratio of Chlorin e6 to Pt has been identified as a promising candidate for a water-soluble anticancer agent with combined photodynamic and chemotherapeutic effects.

Hybrid materials based on carbon fabric modified with molybdenum oxides and polyvynylpirrolidone, synthesized by method of non-stationary electrolysis are studied. The main phases of hybrid materials according SAED data were molybdenum oxides MoO₃, Mo₄O₁₁, Mo₈O₂₃. The specific capacitance of hybrid materials was 985 mF/cm² at current density 5 mA/cm². Hybrid materials are characterized by capacitance retention on level 82% after 10 000 charge-discharge cycles.

In present paper 20 published models/equations for fracture toughness determination were analyzed by the following parameters: crack length after penetration, microhardness and fracture toughness of the ceramics. The following criteria were chosen to meet the practical use of the formulas for structural ceramics: (i) material hardness belongs to the range of 16–20 GPa with the maximum coverage of this range, (ii) c/a ratio lies in the range of 2.5–3, (iii) equation contains explicit and simple to measure parameters. Equations that meet all of these criteria were tested on composite ceramics based on alumina, zirconia and silicon nitride and it turned out that equation, proposed by Antstis et al. being simple, most cited and accounting the elastic-plastic characteristics of the material, suits best for such ceramics. At the same time equation by Evans and Wilshaw can be recommended when it is impossible to determine, for example, the elastic modulus of the material. Equation, derived by Niihara, Morena and Hasselman, appeared to fit best at low loads (<20 N) only where Palmquist crack system is formed.

The possibility of synthesis a water-soluble palladium complex with Chlorin e6 as part of the Photoditazine drug has been investigated. Based on data from electronic absorption and luminescence spectroscopy, it was concluded that a complex of palladium and Chlorin e6, with palladium located in a tetrapyrrole ring, was formed. In particular, it was found that the luminescence intensity and the wavelength of the Chlorin e6 band increased in solutions containing Chlorin e6 and palladium. Mass spectrometry analysis determined that the complex was [Pd : Chlorin e6]^2–. The complex of Chlorin e6 with palladium in a 0.5 : 1 molar ratio was identified as most promising for further research due to its rapid accumulation in tumor cells, low toxicity and minimal impact on cellular membrane integrity.