Protection of Metals and Physical Chemistry of Surfaces最新文献

This comprehensive review presents the main characteristics of plasmonic nanoparticles (PNPs), especially consisting of noble metal nanoparticles (NMNPs) such as silver (Ag), gold (Au), and palladium (Pd), and brief information on their synthesis methods. The physical and chemical properties of the metal NPs are described, with a particular focus on the optically variable properties (surface plasmon resonance-based properties) and surface-enhanced Raman scattering of plasmonic materials. Plasmonic NPs have attracted particular attention due to their strong optical, electrical, biological, and catalytic effects, which are accompanied by surface plasmon resonance characteristics of plasmonic NPs. Their assemblies enable fine-tuning of these effects with unprecedented dynamic range. In turn, the uniquely high polarizability of plasmonic nanostructures and related optical effects exemplified by surface-enhanced Raman scattering and red–blue color changes give rise to their application to bio-sensing. In addition, this review covers ways to achieve advances by utilizing their properties in catalytic, sensing, and biological studies. These descriptions will help researchers new to nanomaterials for catalytic and biomedical diagnosis to understand the related knowledge easily. They will also help researchers involved in the biomedical field to learn about the latest research trends.

A comparative study was conducted of methane adsorption by CH₄, propane (C₃N₈), and n‑butane (n-C₄N₁₀), as well as depleted mixtures of them, on the highly active microporous adsorbent KAUSORB-VA with a micropore volume of 0.68 cm³/g at temperatures of 288, 303, and 335 K in a wide range of absolute pressures up to 4 MPa. The isotherms of individual gas adsorption were calculated using the Dubinin–Radushkevich equation of the theory of volumetric filling of micropores. The adsorption of binary mixtures of CH₄/C₃N₈ and CH₄/n-C₄N₁₀ with a component content of 80/20 and 85/15 mol %, respectively, was calculated using the IAST method. The potential selectivity of the KAUSORB-VA adsorbent in adsorption gas-separation processes was assessed for their further use.

This study focuses on the synthesis and characterization of zinc oxide nanoparticles (ZnO NPs) obtained through an eco-friendly method, using an aqueous lemon leaf extract as a reducing and stabilizing agent. The experimental protocol involved the preparation of the plant extract, followed by its mixing with zinc chloride and deposition onto polished copper substrates by pyrolytic spray at 350°C, then annealed at 400°C. The formation of ZnO NPs was confirmed by various analysis techniques, including X-ray diffraction (XRD), UV–Vis spectrophotometry, and scanning electron microscopy (SEM). The synthesized nanoparticles exhibited a homogeneous morphology, with an average crystalline size of 21.92 nm and a bandgap energy of 2.95 eV, indicating significant ultraviolet absorption. The electrochemical properties of the ZnO NPs/Cu were evaluated for glucose detection in an alkaline medium, showing distinct oxidation and reduction peaks. A decrease in current was observed with increasing glucose concentration, attributed to the saturation of active sites and parasitic reactions. The detection sensitivity was 947.37 µA/cm² mM before annealing and 2703.43 µA/cm² mM after annealing, representing a 2.85-fold improvement following thermal treatment. Moreover, their performance as supercapacitors was analyzed, revealing a specific capacitance of 175 F/g before annealing and the peak current was plotted 365 F/g after annealing, thus confirming a marked increase in energy storage capacity after annealing. These results demonstrate the potential of ZnO NPs synthesized via this hybrid green-spray pyrolysis approach for dual applications in glucose sensing and energy storage.

This study investigated two groups of surgical suture materials—nonabsorbable (polyethylene terephthalate, polyamide, and silk) and absorbable (glycolic/lactic acid copolymer)—before and after accelerated aging. The analysis employed tensile strength testing, Fourier-transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). Following domestic and international standards for polymer aging, the samples were subjected to the following initial accelerated aging conditions: 168 days at 50°C, 84 days at 60°C, and 42 days at 70°C. The results demonstrate that accelerated aging does not alter the chemical or phase structure of the nonabsorbable sutures. Their strength properties complied with the relevant standard requirements, which supports the suitability of these test conditions for such materials. However, not all initial test conditions suit absorbable sutures because these fibers lose a significant portion of their strength because of pronounced chemical and physical changes. FTIR and DSC data support the use of more moderate accelerated-aging conditions for absorbable sutures.

In this work, an anticorrosion coating based on acrylic varnish and nanosized zinc oxide powder obtained in a Nanospray Drying B-90 apparatus was obtained and tested. Using the potentiodynamic polarization method, it was established that the efficiency of coating protection is 98 and 81% in acidic and neutral environments of dilute electrolytes, respectively. Based on X-ray phase analysis and optical and electron microscopy, it was shown that the addition of zinc oxide increases the number of adhesion centers, resulting in better adhesion of the polymer coating to the substrate and preventing the manifestation of the Fe₃C phase on the surface.

Titanium and its alloy, particularly Ti6Al4V, have been extensively utilized in biomedical applications due to their excellent mechanical properties, corrosion resistance and biocompatibility. However, their potential drawbacks are their vulnerability to fluoride-induced corrosion and the release of potentially toxic metal ions, which poses challenges in long-term medical applications. Plasma electrolytic oxidation (PEO) is an effective surface modification process that improves corrosion resistance, wear resistance, and biocompatibility by creating a porous ceramic oxide layer on the metal surface. In this study, Ti6Al4V alloys processed with PEO in a phosphate-based electrolyte containing suspended zirconia (ZrO₂) microparticles. The findings substantiated the integration of zirconia into oxide layer as a homogeneously porous structure. Corrosion analysis showed a dramatic enhancement in corrosion resistance of the zirconia-modified Ti6Al4V over Ti6Al4V without zirconia coatings. Microstructural characterization through SEM and EDS showed a uniform distribution of zirconia, which is responsible for improved surface stability. The coating thickness increased up to 27.6 µm with 6 g/L ZrO₂, improving protective properties but also leading to excessive porosity at higher concentrations. Wettability and biofilm adhesion tests revealed enhanced antibacterial efficacy, especially against E. coli and S. epidermidis. Roughness tests also validated enhanced osseointegration potential. All these findings support that PEO-based zirconia addition is a promising solution for enhancing the longevity and efficacy of titanium alloys in biomedical fields.

The influence of Ti doping amount on the corrosion resistance of Cr microalloy steel was investigated by simulating a harsh marine atmospheric corrosion environment. The results indicate that Ti significantly enhances the thermodynamic stability of Cr microalloy steel and increases its corrosion potential. Additionally, as the Ti doping level increases from 0 to 0.087 wt %, the protective capability of the corrosion product layer is progressively improved. The corrosion rate of Ti-doped steel decreases from 2.24 to 1.75 mm/year, representing a 21.9% reduction compared to that of undoped steel. However, when the doping level exceeds 0.087 wt %, the enhancement in corrosion resistance becomes minimal, with little significant change in the corrosion rate. Furthermore, long-term corrosion studies of the product layers revealed a strong synergistic interaction between Ti and Cr, leading to greater enrichment of Cr in the product layers formed on Ti-doped steel. Moreover, Ti promotes the formation of γ-Fe₂O₃, which facilitates the development of a denser and more stable protective oxide layer.

Upon an interaction of protoporphyrin IX free base with an excess of vanadyl sulfate in refluxing dimethylformamide, corresponding vanadyl protoporphyrin is obtained in a high yield. The structure of vanadyl protoporphyrin is determined by the data of EAS and mass spectrometry. An analysis of the temperature dependence of the phosphorescence spectra of a polystyrene film including vanadyl protoporphyrin is conducted upon thermostating using a cryostat. It is found that, throughout the entire range of temperatures of from –195 to 25°C, the ratio of the intensity of transitions of phosphorescence ⁴T₁–²S₀ and ²T₁–²S₀ changes gradually and completely reversibly without hysteresis effects. An analysis technique of phosphorescence spectra of vanadyl protoporphyrin for the determination of temperature by the shape of a phosphorescence spectrum that contains one pronounced maximum with a set of shoulders in the red visible region is proposed.

Perovskite solar cells (PSCs) are famous for their remarkable efficiency and promising potential for low-cost fabrication, which is configured with a fluorine-doped tin oxide (FTO) base window layer and methylammonium lead iodide (CH₃NH₃PbI₃) absorption layer found better electrical performance. However, optical loss due to moderate optical properties and degradation is the main challenge for FTO-configured perovskite solar cells. This research intends to enhance the optical properties and electrical properties of hybrid perovskite solar cells featuring 10, 20, 30, and 40 nm of tin oxide (SnO₂) electron transport layer (ETL), which is formed through the atomic layer deposition technique. Final perovskite solar cells consist of FTO/SnO₂/CH₃NH₃PbI₃/poly(triarylamine) (PTAA)/fullerene (PCBM)/copper (Cu) layers. However, the role of SnO₂ ETL thickness in influencing the efficiency and stability of PSCs remains an active area of investigation. The findings underscore the potential of tailored ETL architectures to elevate the overall performance and environmental robustness of PSCs. The 40 nm SnO₂ layer, optimized for the highest power conversion efficiency (PCE) of 24.0%, achieved the greatest short-circuit current density (J_sc) of 25 mA/cm², open-circuit voltage (V_oc) of 1.18 V, and fill factor (FF) of 78.1%. This configuration also recorded the highest absorption coefficient of 3.0 × 10⁴ cm^–1 and an optical band gap of 1.59 eV in the perovskite absorber layer, driven by enhanced charge extraction and minimized recombination.

The influence of the “aqueous solution of copper sulfate–hydrogel sorbent based on chitosan and silicon dioxide” heterophase system have been studied. The most important sorption characteristics of the process of extracting Cu(II) ions from aqueous solutions of CuSO₄ in the linear coordinates of Langmuir and Freundlich, the theory of volumetric filling of micropores (TVFM at n = 2), and Temkin. The values of changes in thermodynamic potentials during the sorption extraction of Cu(II) cations from aqueous solutions in the temperature range of 298–333 K were obtained. In general, the process is thermodynamically spontaneous and exothermic; the characteristic curves of the sorbent indicate that the conditions of temperature invariance are met. The distribution of isosteric heats of sorption with increasing degree of surface filling was obtained.