مجله مواد و فناوری های پیشرفته
سال یازدهم شماره 2 (تابستان 1401)

Alpha-tricalcium phosphate can be used as a powder component in the preparation process of calcium phosphate cements in hard tissue applications. In this study, the mentioned powder was synthesized through chemical precipitation method using calcium nitrate and diammonium hydrogen phosphate as the raw materials. The resulting powder was heat-treated at 1250 °C and quenched at the ambient temperature. The results of X-Ray Diffraction (XRD) analysis and Fourier Transform Infrared (FTIR) spectroscopy confirmed the formation of crystalline Alpha-tricalcium phosphate phase and presence of P-O chemical groups, respectively. The Single-component cement was prepared using Alpha-tricalcium phosphate powder with the liquid phase containing 2.5 % disodium hydrogen phosphate. The resulting cement sample had an initial setting time of 17 1 minute and the compressive strength of 21 2 MPa. The XRD and FTIR experiments revealed the formation of a great amount of calcium deficient hydroxyapatite as the resulting cement product. According to the findings, the cement setting occurred through the hydrolysis of Alpha-tricalcium phosphate powders and the formation of calcium deficient hydroxyapatite nanoflakes of approximately 500 nm in length. Finally, the cement acellular bioactivity experiment confirmed that the hydroxyapatite was formed on the outer surface of the cement during 14 days of immersion in the simulated body fluid.

In this study, the change of the structure of Nepheline (Neph) (including two minerals, syenite and microcline) was studied, using hydrothermal and milling methods by the 2 % mol. soda (NaNeph) and 30 wt % lime (CaNeph), respectively. The X-ray diffraction and Raman spectra show that, the structure of the microcline phase in the (CaNeph) sample remained stable but the structure of Nepheline was somewhat degraded. The main characteristic XRD peaks of Nepheline in the NaNeph sample at 28º stayed compared to the CaNeph one. According to Raman spectroscopy the structural order of alumina-silicate rings in CaNeph sample was higher than Neph due to the 3 hs. milling and entering of the alkaline earth elements into the ring structure. Finally, Nepheline bearing glass samples with chemical composition of 6 wt % Al2O3-65.5 wt % SiO2-13 wt % Na2O-16 wt % CaO were used. The amounts of used Nepheline in the composition of glasses were 25 to 38 % by weight (depending on the final composition). The difference in thermal behavior of GCaNeph, GNaNeph and GNeph glasses was compared by means of thermal analysis (DTA/TG) and volumetric change (dilatometry). The glass transition temperatures were 25, 37 ºC increased in GCaNeph and GNaNeph compared to Neph samples (without processing) respectively. The chemical resistance of GCaNeph and GNaNeph glasses in the present work was 4 times higher than GNeph. The density of GCaNeph glass in the present work was 0.9 g/cm3 higher than GNeph.

The main objective of this research was to fabricate a flexible Multi-component Nanocomposite (MN) cover with high efficiency to absorb Electro-Magnetic Waves (EMW). For this purpose, nine MNs containing Carbon Nanotubes (CNTs), core-shell structure of Polyaniline-Fe3O4 (PANI), and Nickel Nanowires (NiNW) were prepared with different weight percentages of 2, 4, and 6 with the thickness of 2 mm within the waterborne polyacrylic. Then, their structural characteristics were investigated through Field-Emission Electron Microscopy (FE-SEM). The protection value of the covers against EMW were measured using a Vector Network Analyzer (VNA) machine at the frequency range of 8-12 GHz. The results revealed that followed by an increase in the concentration of the fillers, they formed a dense and conductive network within the matrix, thus leading to more interaction by EMW and eventually more absorption. The simultaneous presence of all three of EMW absorbtion enhancers including CNTs, PANI, and NiNW offered a more effective shielding than that in both single and double components by improving the matrix electrical and magnetic conductivity. Finally, the evaluations proved that the nanocomposite containing the mentioned three fillers with the wight percentage of 6 wt % and effective shielding of 22 dB exhibited the most ideal performance between other nanocomposites over the X-frequency range.

Energy storage is one of the most important issues in the scientific community. Among the other significant concerns in this field are the economic and environmental issues. Chemical deposition has attracted the attention of a number of researchers owing to its advantages such as its binder-free, fast, and simple electrode, compared to the electrochemical synthesis, as well as its one-step production and coating. In this research, a coating of Nickel hexacyanoferrate nanoparticles (NiHCF) was deposited on a Stainless-Steel Mesh (SSM) substrate through the chemical deposition method. The electrode was analyzed through X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FE-SEM) methods based on which, the presence of nickel hexacyanoferrate nanoparticles on the substrate was confirmed. The electrochemical performance of the binder-free NiHCF electrode as the supercapacitor electrode in a solution containing 0.5 M sodium Sulfate (NaOH) aqueous electrolyte (vs. Ag/AgCl) electrode was evaluated using the cyclic voltammetry and galvanostatic charge/discharge tests. According to the findings, the mentioned electrodes were characterized by a high specific capacitance of 465.7 F g-1 and current density of 1 A g-1, an appropriate rate capability and structure. The current research primarily aimed to obtain an electrode with high specific capacity and acceptable stability, and the obtained results highlighted its wide applications as the supercapacitor.

In the present study, gelatin/chitosan/zinc oxide hydrogels were prepared through solvent casting method in combination with lyophilization. In addition, the effects of adding 1.5 wt % zinc oxide nanoparticles on the microstructural and physico-chemical characteristics of genipin-crosslinked scaffolds were evaluated. The porosity of the newly formed hydrogels increased from about 93 up to 94 % (P < 0.05). Images taken by a Scanning Electron Microscope (SEM) illustrates the formation of a porous microstructure of distinct interconnected holes with an average size of 200 microns. Water absorption capacity of nanocomposite hydrogels at room temperature and 37 °C decreased from 1043 to 988 and 1206 to 1040 %, respectively; however, a significant increase in their initial swelling rate was observed. Upon adding nanoparticles, the in vitro degradation of scaffolds occurred faster than usual. According to the findings of this research, gelatin/chitosan/zinc oxide hydrogels which is characterized by favorable microstructural characteristics (i.e., uniform distribution of interconnected pores) and high initial swelling rate can be used as a potential substrate in the field of tissue engineering.

Injectable hydrogels that mimic heart tissues can be considered a promissing perspective towards the future developments of cardiac tissue engineering. This study aims to fabricate an injectable, thermosensitive hydrogel consisting of chitosan/gelatin/glycerol phosphate. Due to their unique electro-conductivity characteristic, hydrogels can provide a suitable environment to accelerate cardiac cell proliferation. Polyaniline/multi-walled carboxylated carbon nanotube (PAni/c-MWNT) was prepared using Sodium Dodecyl Sulfate (SDS) emulsion. To prevent the interaction between the PAni/c-MWNT nanocomposite and hydrogel, the nanocomposite was coated with gelatin to form polyaniline/carboxylated carbon nanotube/gelatin (PAni/c-MWNT/G). The PAni/c-MWNT/G nanocomposite was then dispersed to provide electrical signals throughout the hydrogel. The gelation time, gel temperature, and mechanical properties of the hydrogel were measured using a rheometer. FTIR spectroscopy results revealed that the interaction between the aniline and c-MWNT/G could change the position of the quinone and benzene peaks. The conductivity of hydrogel-containing nanocomposite was found to be higher than that of c-MWNT and PAni. Scanning Electron Microscopy (SEM) confirmed the uniform distribution of PAni/c-MWNT/G nanocomposite throughout the hydrogel. The degradation rate of conductive hydrogel is lower than that of pure hydrogel. The MTT assay test showed the biocompatibility of the cell-hydrogel. Finally, Mesenchymal Stem Cells (MSCs) were cultured in the hydrogels for 14 days. Cell adhesion, cell viability, and proliferation were also examined. This study utilized PAni/c-MWNT/G, for the first time, to enhance the electro-conductivity of chitosan/gelatin/glycerol phosphate hydrogel. This conductive thermosensitive injectable hydrogel can be used to regenerate cardiac tissue and other electroactive tissues.