Doping with nitrogen atom is an effective way to modify the electronic and magnetic properties of graphene. In this paper, we studied the effect of the number of dopant atoms on the electronic and magnetic properties of the two most common nitrogen bond configurations in N-doped graphene, that is, graphitic and pyridinic, using density functional theory (DFT). We found that the formation of graphitic and pyridinic configurations can initiate the transition of the electronic properties of graphene from semimetal to metal with n-type conductivity for the graphitic configuration and p-type conductivity for the pyridinic configuration. The formation of a bandgap-like structure was observed in both configurations. The bandgap increased with the increase in the number of dopant atoms. We also observed that the formation of graphitic configuration did not cause a transition to the magnetic properties of graphene even though the number of dopant atoms was increased. In the pyridinic configuration, the increase in the number of dopant atoms caused graphene to be paramagnetic, with the remarkable total magnetic moment of 0.400 μ_B per cell in the pyridinic-N₃ model. This study provides a deeper understanding of the modification of electronic and magnetic properties of N-doped graphene by controlling the bond configuration and the number of nitrogen dopants.

A polyvinyl alcohol (PVA) hydrogel loaded with guava leaf extract (GLE) has potential applications as a wound dressing with good antibacterial activity. This study succeeded in fabricating a PVA hydrogel containing GLE using the freeze–thaw (FT) method. By varying the GLE concentration, we can adjust the physical properties of the hydrogel. The addition of GLE results in a decrease in cross-linking during gelation and an increase in the pore size of the hydrogels. The increase of the pore size made the swelling increase and the mechanical strength decrease. The weight loss of the hydrogel also increases because the phosphate buffer saline (PBS) dissolves the GLE. Increasing the GLE concentration caused the Fourier-transform infrared (FTIR) absorbance peaks to widen due to hydrogen bonds formed during the FT process. The crystalline phase was transformed into an amorphous phase in the PVA/GLE hydrogel based on the X-ray diffraction (XRD) spectra. The differential scanning calorimetry (DSC) characterization showed a significant decrease in the hydrogel weight over temperatures of 30–150 °C due to the evaporation of water from the hydrogel matrix. The zone of inhibition of the PVA/GLE hydrogel increased with antibacterial activity against Staphylococcus aureus of 17.93% per gram and 15.79% per gram against Pseudomonas aeruginosa.

Two different components of tunneling current in the $\text{TiN}/{\text{HfSiO}}_{\text{x}}\text{N}/{\text{SiO}}_2/\text{p-Si}\left(100\right)$ metal-oxide-semiconductor capacitor have been presented. The tunneling currents were calculated by taking into account a longitudinal-transverse kinetic energy coupling. The calculated tunneling currents were compared with that measured ones by employing the electron and hole effective masses and phase velocities as fitting parameters. It has been shown that hole tunneling currents dominate at low voltages whereas at high voltages the tunneling currents are mainly contributed by electrons. It has also been found that the effective mass of hole in the ${\text{HfSiO}}_{\text{x}}\text{N}$ layer is higher than that of electron. The gate electron and substrate hole velocities are $1\times {10}^5\text{m}/\text{s}$ independent of the ${\text{HfSiO}}_{\text{x}}\text{N}$ thickness. In addition, it is speculated that the electron and hole effective masses in the ${\text{HfSiO}}_{\text{x}}\text{N}$ layer perhaps increase as its thickness decreases.

The paper initially focuses on the characteristics of Polyvinyl Alcohol (PVA) hydrogel as smart delivery media, such as chemical stability, biocompatibility, and capacity for controlled release of bioactive compounds. Then, it discusses the effect of loading bioactive compounds into PVA hydrogel, considering their stability of delivery media, controlled release, and targeted delivery, enhancing therapeutic outcomes. Loading bioactive compounds such as diphlorethohydroxycarmalol (DPHC), curcumin, carotenoids, andrographolide, and flavonoids into PVA hydrogels can enhance biomedical functionalities. These functionalities include improved drug delivery, wound dressing efficacy, tissue engineering potential, and contact lens applications. Further, while previous review papers have extensively covered aspects such as the source of bioactive compounds, extraction methods, synthesis of PVA hydrogel, and various biomedical applications, there remains a gap in the literature in which no studies have systematically explored the loading of bioactive compounds into PVA hydrogel. This targeted investigation distinguishes our work from previous studies and contributes a novel perspective to the expanding hydrogel market. In light of the projected compound annual growth rate of 7.15% in the hydrogel market from 2021 to 2028, this study provides a pioneering overview of recent advancements in bioactive compound-loaded PVA hydrogels. Finally, this review outlines the challenges in optimizing bioactive compound-loaded PVA hydrogels’ performance and their biomedical application. In the future direction, this review explores their potential in smart delivery media, such as optimizing the loading efficiency and releasing kinetics to specific target therapeutic, crosslinking with double or triple network hydrogels, and convergence of nanotechnology with hydrogel that become frontiers in precision medicine.