Advanced Ceramics Progress
Volume:7 Issue: 3, Summer 2021

The main objective of the present study is to evaluate the mechanical properties, biocompatibility, and bioactivity behavior of scaffolds made of hydroxyapatite (HA)-modified by MnO2 and Palladium (Pd) for biomedical applications. Throughout the research, HA, MnO2, and Pd were developed using sol-gel and precipitation methods, respectively. The properties of the scaffolds were determined using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX), atomic absorption, and Brunauer−EmmeS−Teller (BET) method. To investigate the in vitro cell proliferation and alkaline phosphatase (ALP) assays, cell culture was done. Furthermore, the mechanical properties of the scaffolds were investigated before and after immersion in Simulated Body Fluid (SBF), and the interaction of Dental Pulp Stem Cells (DPSCs) with the nanocomposite scaffolds was assessed. The obtained results showed that the HA/MnO2/Pd scaffolds were characterized by higher compressive strength (35.72%), toughness (35.68%), microhardness (80%), and density (0.44%) than HA/MnO2/Pd filled by chitosan (CS) binder scaffolds. The biocompatibility properties indicated higher cell proliferation and ALP assay on the HA/MnO2/Pd filled by CS scaffolds than those of HA/MnO2/Pd scaffolds.

This study investigates the antibacterial activity of TaN-Ag nanocomposite thin film as well as hydrophobic properties. TaN-Ag nanocomposite thin film was deposited on cleaned 316 stainless steel, which is suggested for surgical tools. The samples were synthesized using DC co-sputtering technique. After deposition, the heat treatment was done at 350 °C at different times. The crystalline structure, topography, and morphology of the thin films were characterized by X-ray diffraction, atomic force microscopy, and scanning electron microscopy, respectively. Also, self-cleaning characteristics and hydrophilic properties were studied using contact angle tests. After four months, antibacterial test was performed using E.coli bacteria. The number of colonies was decreased up to 50%, after 6 hours without using UV irradiation during the incubating time. The results showed that the average size of nanoparticles was less than 50 nm and the self-cleaning properties of the TaN-Ag nanocomposite thin films were improved by surface roughness; so, the bacterial adhesion was reduced.

In the present study, in vivo properties of poly (D/L) lactide (PDLLA)/polycaprolactone (PCL)/bioactive glass nanocomposites (PPB) and PDLLA/PCL blends (PP) were investigated up to six months. The in vivo results from the implants inserted on canine models indicated that the weight losses of PPB and PP were approximately 60 and 70%, respectively. In addition, the average molecular weight of both specimens decreased as a function of grafting times; however, such decrease in trend of blends was more considerable than that in nanocomposites. Moreover, the obtained histological images of the animal model up to six months of implantation distinguished the formation of the new bone within the implanted area, while no osteitis and osteomyelitis or structural abnormality were observed. Overall, the animal in vivo tests results of implants within a period of 180 days confirmed the good biocompatibility among them and appropriate degradation behavior of PPB, hence a proper candidate for Anterior Cruciate Ligament Reconstruction (ACLR) screws.

In the present study, a multiferroic (K0.5Na0.5NbO3)-22.5 Vol. % (BaFe12O19) composite was successfully obtained from conventional sintering (abbreviated as CS) method at 1080 °C. To compare the dielectric properties of the samples, lead-free K0.5Na0.5NbO3 (abbreviated as KNN) piezoceramics were prepared using CS method at 1125 °C. The structure and morphology were determined by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), and the dielectric properties of samples were also investigated. In the X-ray spectra of composite samples, all peaks related to the KNN and BFO phases were observed without any trace of the second phase. In the SEM images of the composite, the distinct cubic morphology of the KNN phase, indicating the formation of the perovskite structure of the compound, and polygonal grains of the BFO phase were observed. The values of relative density, dielectric coefficient, and loss factor of the lead-free KNN ceramic at the sintering temperature of 1125 °C were measured to be 91 %, 390, and 0.02, respectively. These values at the sintering temperature of 1080 °C were about 92 %, 200, and 0.18, respectively. Although the dielectric properties of KNN-BFO composite were lower than those of pure KNN, the presence of magnetic phase could create magnetic properties and, consequently, multiferroicity in the KNN-BFO composite. The dielectric properties also confirmed that this composite can be regarded as a new multiferroic composite.

In this study, concrete samples were prepared by adding 0.1 wt. % Graphene Oxide (GO) and 50 wt. % Ground Granulated Blast Furnace Slag (GGBFS). Tests on the mechanical and chloride permeation properties were also conducted. Concrete samples were exposed to pressurized 3.5 % NaCl aqueous solution under a certain time and temperature condition. The water pressures were 0.1, 0.3, and 0.7 MPa, respectively. The chloride concentration profiles under different conditions were measured. The results indicated that addition of 0.1 wt. % GO and 50 wt. % GGBFS would increase the compressive strength of the concrete sample up to 19.9 % during 28 days and 17.6 % during 90 days compared to ordinary concrete sample. Concrete with a combination of 0.1 wt. % graphene oxide and 50 wt. % granular slag witnessed an increase in its flexural strength up to 15 % during 28 days and 13.6 % during 90 days. Compared to the ordinary concrete, 90-day cured concrete containing GGBFS and GO undergone high reduction in Rapid Chloride Permeability (RCP) from 4012 C to 1200 C. Chloride ion content was substantially enhanced upon increasing water pressure and exposure time. In this study, convection-diffusion coupling was the main mechanism of the chloride ion transfer in the concrete. The mix with 0.1 wt. % GO and 50 wt. % GGBFS exhibited acceptable performance in terms of chloride penetration in the concrete. Compared to ordinary concrete, this admixure reduced the chloride penetration by 17.6 % in 90 days. Chloride ion penetration was curtailed while adding GO and GGBFS to the ordinary concrete. The effects of pozolanic reaction in the concrete leading to the filling of the pores were significant factors in the proposed curtailment mechanism.

In this study, Y3Al5O12-MgAl2O4 (YAG-Spinel) composites, with different molar ratios (1:1 and 1:3), were in-situ fabricated using Reactive Spark Plasma Sintering (RSPS) technique. To this end, Al2O3, MgO, and Y2O3 powders were used as the starting materials. In-situ formation of YAG-Spinel composites was investigated based on the reaction 3.5 Al2O3 + MgO + 1.5 Y2O3 → Y3Al5O12 + MgAl2O4. Both synthesis and densification processes were accomplished using a single-cycle RSPS with one-step heating. The RSPS process was performed at a sintering temperature of 1300 °C for 30 min hold time with a maximum uniaxial pressure of 90 MPa under vacuum conditions. The synthesized phases and microstructures were investigated by X-ray diffraction and field emission scanning electron microscopy. The unwanted phases such as YAP (YAlO3) in a composite microstructure were removed using LiF additive. LiF was used as a sintering aid in the process of sintering. The in-situ synthesized YAG-Spinel composites exhibited no internal infrared transmittance over the infrared wavelength ranges of 2.5-25 µm.