Mongolian Journal of Engineering and Applied Sciences

Review of degradation behaviour biodegradable magnesium MgZnCa alloys

Konul Vaqif Amirmatova — 2025-06-29

Metals such as stainless steel and titanium have long been used in orthopedics due to their strength and wear resistance. However, magnesium-based alloys, with mechanical properties closer to those of bone, are gaining increasing attention for biomedical applications. Magnesium implants are biodegradable, lightweight and offer advantages such as reduced stress shielding and the elimination of secondary surgery. Despite the above-mentioned advantages, Mg-based biomaterials have poor corrosion resistance in physiological environments. This study focuses on biodegradable Mg-Zn-Ca alloys, which are characterized by high biocompatibility and satisfactory mechanical properties. The degradation process is influenced by various factors such as the qualitative and quantitative composition, heat treatment method, microstructure, grain size, phase presence, and other parameters. Alloying with elements such as Zn and Ca helps improve the mechanical and corrosion properties; however, it should be noted that at certain concentrations can reduce ductility and accelerate degradation. The corrosion process results in the formation of magnesium hydroxide, magnesium chloride, hydrogen gas, and other compound groups. Although the presence of hydroxyl, calcium, and phosphate ions can promote the formation of protective layers that slow down corrosion, the formation of magnesium chloride further accelerates the degradation process. The article discusses the degradation process of magnesium alloys, emphasizing the importance of optimizing their chemical composition and the choice of heat treatment method, as well as the influence of these factors on microstructural and phase characteristics.

Synergistic antibacterial activity of ciprofloxacin-loaded silver and mesoporous silica core/shell nanoparticles

Jargalmaa Lunee — 2025-05-27

The misuse and overuse of antibiotics have led to the rise of antibiotic-resistant microorganisms, which are projected to cause approximately 10 million deaths annually by 2050, surpassing cancer-related mortality. This growing crisis requires the development of new antibacterial strategies. Nanoparticles (NPs) have emerged as promising antimicrobial agents, with silver nanoparticles (AgNPs) demonstrating potent antibacterial activity through mechanisms such as controlled silver ion release, increased bacterial membrane permeability, and reactive oxygen species (ROS) generation. In this study, ciprofloxacin-loaded silver and mesoporous silica core/shell
nanoparticles (CIPRO-Ag@MSNs) exhibited synergistic antibacterial effects against both Gram-positive bacteria (Staphylococcus aureus and Micrococcus luteus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), significantly improving the efficacy of ciprofloxacin. Notably, mesoporous silica-coated silver nanoparticles (Ag@MSNs) improved biocompatibility by reducing excessive bacterial killing, highlighting their potential as a safe and effective nanosystem for bacterial infection treatment.

Effect of particle size on the fabrication of copper-based nanocomposites via planetary ball mill with DEM simulation

Naranzaya Bayarsaikhan — 2025-05-20

To improve the properties of copper, a copper-based nanocomposite was fabricated using carbon nanotubes (CNTs), with copper powder produced by Steppe Powder LLC. Copper powders with two different raw particle sizes (70 µm and 110 µm) were selected, and various milling parameters, including milling time (1, 3, 6, and 12 hours), rotational speed (100, 300, and 500 rpm), and ball size (5 mm, 10 mm), were adjusted to compare the resulting composite materials. A scanning electron microscope (SEM) was used to analyze particle size and morphology, while a particle size analyzer (PSA) was employed to determine the particle size distribution. A field emission scanning electron microscope (FE-SEM) was used to examine the dispersion of CNTs on the copper particles. Additionally, the discrete element method was applied to study the milling mechanism in the ball milling machine. The results indicated that for a rotational speed of 300 rpm, increasing the milling time led to the flattening and growth of the composite particles, whereas at 500 rpm, longer milling times resulted in more flattened and significantly reduced particle sizes. Regarding CNT dispersion, at 300 rpm with a milling duration of 12 hours, CNTs were weakly attached to the copper surface. In contrast, at 500 rpm for 12 hours, CNTs were successfully embedded into the surface of the copper particles.