مجله مواد و فناوری های پیشرفته
سال دهم شماره 3 (پاییز 1400)

Regarding the suitable potential for wind energy in Iran, it is possible to employ small wind turbines such as large ones to supply part of the electricity load of the country. The present study deals with materials used in small horizontal axis wind turbine blades and their fabrication methods. To this end, the wood and the composite, as the two main materials used in blades, have been investigated. Then, the main methods of producing wooden and composite blades have been analyzed. Finally, the 3D printing method and polymer materials used in this technique have been introduced. The study shows that the fatigue parameter has an important role in determining the blade’s material and the fabrication method. Despite the environmental benefits of using wood, the complexity and the manufacturing costs prevent rapid and affordable production of wooden blades. On the other hand, the mass production of composite blades is more economical, although it has environmental impacts. Despite the fatigue issue of the 3D printed blades, the 3D printing method is a fast and relatively inexpensive technique for fabrication of small wind turbine models for wind tunnel tests.

In this study, a new method for antibacterialization of historical cotton fabrics was evaluated. Due to the fact that the desired results of the application of nanomaterials in the field of protection of historical textiles in Iran have not been recorded so far, the antibacterial properties of titanium dioxide nanocloid on historical cotton fabrics were investigated. The experimental sample was prepared by simulating a study sample and then sprayed titanium dioxide nanocloid on it and the samples were aged for 72 hours. Scanning electron microscopy (FE-SEM) was used to observe the distribution of nanoparticles on the surface of fabric fibers and to control its antibacterial properties, bacterial culture was used in nutrient agar-based salt medium. Electron microscopy showed the presence of nanoparticles on the surface of the fabric fibers. Subsequently, culturing Pseudomonas aeruginosa and Bacillus subtilis in saline medium resulted in 60 % reduction in Pseudomonas aeruginosa growth and 30 % reduction in Bacillus subtilis in the presence of nanomaterials, which can be improved by optimizing the method, quality and number of nanoparticles. In addition, due to the observed color change in the fabric after aging of the samples and the importance of this in the preservation of historical monuments, optimization of the colloidal solution used is necessary.

In this study, hydroxyapatite was produced and produced from yellow fish bones by hydrothermal method at two temperatures of 150 and 200 °C using water and alcohol additives. X-ray diffraction (XRD) analysis, infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to study the fuzzy structure, identification of powder organic compounds and particle morphology, respectively. XRD results showed that the peaks related to hydroxyapatite are in the range . According to the obtained results, it was found that to form the structure of hydroxyapatite, a minimum temperature of 200 degrees Celsius with water additive solution is required. The FTIR results also showed that the peak of 1032 cm-1 belongs to the chemical group and the peak of 560 cm-1 belongs to . As a result, the obtained hydroxyapatite powder ( ) can be used in medical work.

Cordierite ceramics are ceramics obtained from a combination of aluminum, magnesium, and silicon oxides. Given that cordierite ceramics have properties such as very low thermal expansion coefficient, low dielectric constant, low density, high hardness, low loss ratio, refractoriness, and good chemical and mechanical stability, they can be used for high temperature applications and tool making. In this study, solid-state synthesis method using oxide powders and silicone resin, followed by cold isostatic press (CIP) method was applied to produce cordierite ceramic with uniform density. Phase detection by X-ray diffraction and determination of density, microhardness, flexural strength, and dielectric constant was performed. The results showed that the α-cordierite phase was synthesized with a density of 2.5 gr/cm-3, hardness of 1151.6 HV, flexural strength of 131.4 ± 6 MPa, dielectric constant of 3.15, andloss tangent of 0.0048 in the frequency range of 8-12.5 GHz.

  The porous ceramic layers of TiO2 were synthesized on Titanium through Plasma Electrolytic Oxidation (PEO) process, using three different electrolytes including hydroxide-based, acetate-based, and phosphate-based solutions. The effects of utilizing different electrolytes on the phase arrangement and microstructural characteristics of the ceramic coatings were then studied using X-ray diffraction, field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results showed that utilizing a KOH-based electrolyte can lead to a heterogeneous structure while the layer that is formed during the PEO process in the acetate-based electrolyte can provide large homogeneous pores in the matrix of rutile-TiO2 and CaTiO3 phases. Using the phosphate-based electrolyte could cause an optimum porous layer consists of anatase-TiO2. The results of cross-section of the samples showed that utilizing the acetate-based electrolyte can lead to formation of the PEO coating including two sublayers. The formation mechanism and microstructural outcome of using phosphate-based electrolyte were finally discussed and graphically illustrated.

 In this research, nanostructured nickel molybdate (NiMoO4) active material was successfully synthesized by a simple hydrothermal route. Structural characterizations were performed using X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR), and surface morphology of the as-prepared material was obtained by Field Emission Scanning Electron Microscopy (FESEM). The results showed that the as-prepared electrode material has a nanometric and rod-shaped structure and their crystal structure was β-phase. Electrochemical evaluations using cyclic voltammetry at various potential scanning rates and galvanostatic charge-discharge at various current densities show that nickel molybdate active material has the high specific capacitance of 730 F g-1 at a current density of 1 A g-1 and a capacity retention of about 63.2 % even with a 10-fold increase in current density to 10 A g-1. The obtained results imply that the as-synthesized NiMoO4 nanorods could be a promising candidate as electrode material for high performance supercapacitors.

Cu2ZnSnS4 (CZTS), a quaternary material, has attracted the attention of many solar cell researchers due to its non-toxic constituents as well as their abundance on Earth. In this paper, the optical and electrical properties of the pure structure doped with the elements of the fifth group of the periodic table were investigated using the density functional theory and GGA approximation. Comparison of density of states for electrons in addition to band structures in both pure, nitrogen-doped, and phosphorus-doped bulk revealed a reduction in the direct band gap of the structure. The study of the obtained optical properties indicated the absorption coefficient increased from for the pure structure to and , respectively, for the replacement of nitrogen and phosphorus with sulfur atoms considering photons with lower energy. Substitution of arsenic, antimony and bismuth atoms instead of tin atoms, which has the lowest formation energy, causes an impurity level in the band gap due to the deganarated states. As a result, by increasing the number of electron transfer states from the valence to the conduction band, the absorption coefficient is increased to an average of for photons with lower energy in the pure structure. Consequently, reducing the gap in some cases, as well as increasing the absorption coefficient for low-energy photons after the addition of impurities, improves the performance of the CZTS plant as an adsorbent layer in solar cells.

The emergence of new sciences such as nanotechnology and its convergence with engineering, biology and medicine, it is raising hopes for the treatment of infectious diseases. One of the infections that has affected a wide range of people in the community Infection of diabetic wounds, one of the causes of which is the bacterium Staphylococcus aureus. In this study, using nanoscience and combining it with the old herbal medicine plant nettle, which is a perennial herb. And ZnO has great nutritional and medicinal value. Zinc oxide (ZnO) nanoparticles were synthesized by nettle coating. Synthesis of ZnO nanoparticles was performed by wetting the nettle plant by chemical method. Structural evaluation of minister nanoparticles of ZnO synthesized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR) was performed. The antibacterial effect of this nanoparticle on antibiotic-resistant Staphylococcus aureus isolated from diabetic wounds was investigated. The antibacterial performance of ZnO/Urtica diocia nanoparticles against Staphylococcus aureus Multi Drug Resistant (MDR) isolates was evaluated by qualitative agar well diffusion test at concentrations of 0.032 to 0.256 g/ml of synthesized nanoparticles. The results of this study showed that the size of the synthesized nanoparticles was 100 nm and spindle-shaped and the highest antibacterial properties of these nanoparticles at a concentration of 0.256 g/ml on antibiotic-resistant Staphylococcus aureus isolates with a halo diameter of 20 mm and the lowest an inhibition of growth was observed at a concentration of 0.032 g/ml. According to the findings of this study it seems that ZnO/Urtica dioica nanoparticles had good antibacterial activity against antibiotic-resistant Staphylococcus aureus isolated from diabetic wounds.