Lu doping nickel oxide thin films using sol-gel spin coated and density functional theory: optoelectronic and magnetic properties.

For the first time, sol-gel spin coating was used to fabricate thin films of NiO doped with lutetium. The films were characterized to determine their crystalline structure, surface morphology, and optical properties as a function of Lu doping concentration. The investigations revealed that the Lu-doped NiO films consisted of nano-polycrystalline particles with a cubic bunsenite structure and (200) preferential orientation. Optical studies indicated that the optical band gap of pure NiO widened with low levels of Lu incorporation before narrowing with higher concentrations. The Urbach energy value for pure NiO initially decreased with 1 at. % Lu-content, from 224 meV to 190 meV, and then continuously increased to 380 meV with more Lu-level. To investigate the effects of Lu doping on the electronics, magnetic, and optical properties of NiO, first-principle computations were performed. The results showed that bulk magnetization underwent significant modifications due to a high hybridization between the Lu-f/d and Ni-d states. This study suggests that NiO doped with lutetium could be used for spin-polarized transport devices and other spin-dependent applications.

Effects of whitening toothpastes on the esthetic properties and surface roughness of a composite resin.

PURPOSE: The aim of this study was to investigate and compare the effects of some whitening toothpastes on the surface roughness and coloration susceptibility of a composite resin, as well as their whitening effectiveness. METHODS: This study was carried out in two different stages. In experiment A, samples were divided into 7 subgroups to compare the surface roughness and coloration susceptibility of the composite resin: distilled water, conventional toothpaste, and 5 different whitening toothpastes. In experiment B, samples were divided into 8 subgroups to compare the whitening effectiveness of the whitening toothpastes: conventional toothpaste, 5 other whitening toothpastes, and two bleaching groups. After toothbrushing simulation, the color and surface roughness of the samples were measured. Data were subjected to one-way analysis of variance, paired t-test and Tukey post-hoc test (α = 0.05). RESULTS: There were no statistically significant differences among the surface roughness values for the groups for any period before and after brushing (P > 0.05). In terms of the coloration susceptibility of the composite resin and the whitening effects of the toothpastes, no statistically significant differences were evident among the groups for any period before and after brushing (P > 0.05). CONCLUSION: The results of this study indicate that effective toothbrushing is more important than the type of toothpaste employed.

Room-Temperature Synthesis of 2D Janus Crystals and their Heterostructures.

Janus crystals represent an exciting class of 2D materials with different atomic species on their upper and lower facets. Theories have predicted that this symmetry breaking induces an electric field and leads to a wealth of novel properties, such as large Rashba spin-orbit coupling and formation of strongly correlated electronic states. Monolayer MoSSe Janus crystals have been synthesized by two methods, via controlled sulfurization of monolayer MoSe2 and via plasma stripping followed thermal annealing of MoS2 . However, the high processing temperatures prevent growth of other Janus materials and their heterostructures. Here, a room-temperature technique for the synthesis of a variety of Janus monolayers with high structural and optical quality is reported. This process involves low-energy reactive radical precursors, which enables selective removal and replacement of the uppermost chalcogen layer, thus transforming classical transition metal dichalcogenides into a Janus structure. The resulting materials show clear mixed character for their excitonic transitions, and more importantly, the presented room-temperature method enables the demonstration of first vertical and lateral heterojunctions of 2D Janus TMDs. The results present significant and pioneering advances in the synthesis of new classes of 2D materials, and pave the way for the creation of heterostructures from 2D Janus layers.

The Risk Evaluation of Tungsten Oxide Nanoparticles in Cultured Rat Liver Cells for Its Safe Applications in Nanotechnology

Tungsten (VI) oxide (WO3) nanoparticles (NPs) are used for many industrial purposes in everyday life. However, their effects on human health have not been sufficiently evaluated. Therefore, the present study was designed to investigate the toxicity potentials of various concentrations (0 to 1000 ppm) of WO3 NPs (<100 nm particle size) in cultured primary rat hepatocytes. The results of cell viability assay showed that the higher concentrations of dispersed WO3 NPs (300, 500 and 1000 ppm) caused significant (p<0.05) decreases of cell viability. Also, dose dependent negative alterations were observed in oxidative status and antioxidant capacity levels after the application of WO3 in cultured rat primary hepatocytes. The results of genotoxicity tests revealed that these NPs did not cause significant increases of micronucleated hepatocytes (MNHEPs) but increased 8-oxo-2-deoxyguanosine (8-OH-dG) levels as compared to the control culture.