Mongolian Journal of Engineering and Applied Sciences

Review of degradation behaviour biodegradable magnesium MgZnCa alloys

Konul Vaqif Amirmatova, Elman Alamgulu Aliyev — Sun, 29 Jun 2025 00:00:00 +0800

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.

A Determination of the Optimal Conditions for the Purification and Recovery of Lactobionic acid from Whey

Wed, 29 Apr 2026 00:00:00 +0800

This study explored the biotechnological production of lactobionic acid through the oxidation of whey, a by-product generated during milk and dairy processing, using the bacterium Gluconobacter frateurii. The bacterial strain used in the experiments was isolated from rotten apples. Identification was carried out by PCR amplification of the 16S rRNA gene, followed by nucleotide sequencing. Comparison of the obtained sequence with those in the NCBI GenBank database confirmed, with 99% similarity, that the isolated microorganism was Gluconobacter frateurii. The identified strain was cultivated in liquid whey-based media to assess its capacity for lactobionic acid production. Based on bacterial growth and cell count analysis, whey derived from industrial acid-treated curd was determined to be the most suitable substrate. The bacterium Gluconobacter frateurii was grown in pretreated whey medium, and lactose concentrations were monitored at 24, 36, 48, 60, 72, 84, 98, 115, and 154 hours after the onset of fermentation. The lowest lactose concentration, 1.18 g/L, was observed after 115 hours, indicating that a fermentation period of approximately four days is sufficient under liquid culture conditions. Following the completion of fermentation, the formation of lactobionic acid was confirmed using thin-layer chromatography (TLC). The product was then isolated through recrystallization, achieving a lactose conversion yield of 74%. The purified lactobionic acid was further analyzed to determine its physicochemical properties and biological activity. This research demonstrates that whey, commonly regarded as a waste product of dairy manufacturing, can be effectively utilized through biotechnological methods to produce lactobionic acid, a high-value compound with important applications in the pharmaceutical and cosmetic industries.

Determining the Optimal Conditions for Extracting Keratin Protein from Chicken Feathers by Hydrolysis

Tue, 28 Apr 2026 00:00:00 +0800

Chicken feathers, a byproduct of poultry farming, consist of approximately 90% keratin protein and are a protein-rich raw material [1]. Keratin is highly resistant to chemical and physical influences and degrades slowly in nature, causing environmental pollution when discarded. Currently, there are no industries or businesses in Mongolia processing waste chicken feathers. To extract keratin protein hydrolysates from chicken feathers, hydrolysis using sodium hydroxide (NaOH), hydrogen peroxide (H₂O₂), and a combination of NaOH and H₂O₂ was employed. The feather microstructure was analyzed by scanning electron microscopy (SEM), protein yield by Kjeldahl and gravimetric methods, molecular weight by SDS-PAGE electrophoresis, structural analysis by Fourier-transform infrared spectroscopy (FT-IR), and thermal properties by thermogravimetric analysis (TG/DTA). The study found that protein yield varied with hydrolysate composition and temperature. A 4% NaOH hydrolysate resulted in the highest yield of 74.8%, while a 2M H₂O₂ + NaOH hydrolysate produced a 61.5% yield. High-temperature, short-duration experiments produced gel-like protein hydrolysates. This research determined some optimal conditions for preparing high-yield keratin hydrolysates from discarded chicken feathers in Mongolia. These findings can serve as a foundation for future industrial applications and further research.

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

Jargalmaa Lunee, Nomin Tserendulam, Erdene Norov — Tue, 27 May 2025 00:00:00 +0800

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

Tue, 20 May 2025 00:00:00 +0800

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.