In this paper, the free vibration of defective NANOGRAPHENE is investigated using Molecular Dynamics Simulation (MD) and Differential Quadrature Method (DQM). The equations of motions and the related boundary conditions are derived based on the differential constitutive relations in conjunction with the classical plate theory via Hamilton’ s principle. Then, DQM is used to investigate free vibration of the NANOGRAPHENE with various boundary conditions. At first, in order to determine natural frequencies more realistically, NANOGRAPHENE mechanical properties are determined using MD simulations. The effects of defects are investigated by analyzing pristine and defective NANOGRAPHENEs containing Stone Wales, vacancy, and Adatom defects. According to the results, the non-dimensional fundamental natural frequency parameter converges to the analytical value for N=10×10. Results indicate that graphene with CCCC boundary conditions has the maximum natural frequency. The minimum value corresponds to the graphene with SSSS boundary conditions. In addition, Non-dimensional fundamental frequency parameter of the nanoplate increases with increasing nanoplate aspect ratio. Finally, defects reduce density, position ratio and elastic moduli of NANOGRAPHENE, which causes a decrease in natural frequency. Stone Wales and vacancy defects decrease NANOGRAPHENE natural frequencies by about 8 and 25 percent, respectively.

Introduction. Graphene-based nanomaterials have shown some degrees of stem cell protection against cell death. Due to their distinctive function, the kidneys are exposed to many toxic substances. On the other hand, minor and trivial effects of stem cells have been reported for the treatment of acute kidney injury (AKI). Here, we explain the use of Graphene oxide (GO) for improving the efficacy of mesenchymal stem cells (MSCs) in the treatment of Cisplatin-induced AKI. Methods. In this study, GO particles were synthesized in our lab. Cisplatin-induced AKI was modeled on rats. Thirty adults male Wistar Albino rats were divided into five groups: control group (did not receive any treatment), Cisplatin group (received 5 mg/ kg cisplatin intraperitoneally), sham group (received 500 µL saline intraperitoneally 5th days after Cisplatin injection), [Cisplatin + MSCs] group (received 5×106 /kg MSCs after Cisplatin injection), and [Cisplatin+ MSCs + GO] group (received 1. 5 mg/kg GO + MSCs after Cisplatin injection. Biochemical analysis of serum creatinine (Cr) and blood urea nitrogen (BUN) levels, as well as histological study of the kidneys in diverse groups were compared. The oneway analysis of variance (ANOVA) and Dunnett’s test were used for comparisons between the study groups. Results. GO improved the effects of MSCs transplantation on serum Cr and BUN in AKI rat models. It also reduced cell death, hyaline casts, and cell debris in the animal models compared to the MSCs group. Conclusion. It could be concluded that GO can enhance the efficacy of MSCs transplantation in the treatment of damaged kidneys.

Background: Composites used in the direct bonding of brackets in fixed orthodontics are considered a suitable environment for the multiplication of cariogenic bacteria and the establishment of microbial plaques by creating a distance between the bracket, tooth surface, and surface properties such as porosity. In the present study, we decided to combine curcumin-reduced nano-graphene oxide (rGO-NCUR) with a composite resin used in orthodontics to achieve a composite with optimal shear bond strength (SBS) and antimicrobial properties against Streptococcus mutans as a main cariogenic bacterium. Methods: In the present study, nanoparticle of graphene oxide (NGO) was synthesized by the modified Hummers’ method using graphite powder and reacted by NCUR to regenerate reduced-NGO (rGO-NCUR). Scanning electron microscopy (SEM) was used to confirm the synthesis of NGO, NCUR, and rGO-NCUR. SBS and antimicrobial activity of Transbond XT composite containing 5% rGO-NCUR were performed against S. mutans biofilms. SPSS software, one-way ANOVA test, and Tukey post hoc test with a significance level equal to or less than 0. 05 were used to analyze the data. Results: The synthesis of NGO, NCUR, and rGO-NCUR in nanoscale was confirmed by SEM. The amount of SBS in the composite sample with 5% w/w rGO-NCUR was 12. 30 ± 0. 65 MPa. The optical density of S. mutans in the biofilm structure formed on composite containing 5% w/w rGO-NCUR was significantly reduced (62. 10%) compared with the control group, namely, original composites used in orthodontics (P < 0. 05). Conclusions: Based on the data of the present study, it can be concluded that composite containing 5% w/w rGO-CUR, without adverse effect on the physical-mechanical properties of composites, can be used as an antimicrobial additive of composites used in orthodontics to control biofilm formation and caries around orthodontic brackets.