NANOSCALE
Year:2020 | Volume:6 | Issue:4 |Papers Count:10

Nanostructures of [Zn(BPD)(H2O)]n (1), (H2BPD = 1, 1'-biphenyl-2, 2'-dicarboxylic acid) supramolecular polymer were synthesized by the sonochemical process. The solid-state conversion of compound 1 nanostructures to nanofibers of [Ag2(BPD)]n (2) coordination polymer was investigated by cation exchange reaction of compound 1 with AgNO3. X-ray diffraction (XRD) analyzes and thermogravimetric and differential thermal analyses (TG-DTA) have shown that this conversion is irreversible. Consideration the crystal structure of these two compounds, which were reported previously, shows that during this process, the ZnO4 coordination sphere in 1 changed to AgO3Ag2˙ ˙ ˙ C6 in 2, thus an organometallic compound was synthesized during this solid-state mechanochemical reaction.

In recent years, great interest has emerged in the development of nanocarriers, especially boron nitride nanostructures for targeted drug delivery. In this research, electronic and adsorption properties of B12N12 and B30N20 nanocages interacted with hydroxycarbamide, as an anticancer drug are investigated by means of density functional theory (DFT) calculations at the B3LYP/6-31G(d) level of theory. All of the computations were performed using the Gaussian 09 software. The adsorption energy (Eads), formation energy, NMR and chemical activity parameters such as gap energy (Egap), chemical hardness (η ), chemical potential (µ ), electrophilicity index (ω ), electron affinity (EA) and dipole moment were calculated to determine the best adsorption site for the anticancer molecule of hydroxycarbamide in boron nitride nanocages. The results showed that all complexes, especially Drug/B30N20 (e) complexe from the side of group – OH of drug molecule are stable in terms of energy and chemical activity. Finally, their interactions are a favorable process. As a consequence, boron nitride nanocages can be considered as a drug delivery vehicle for the transportation of hydroxycarbamide drug within the biological systems.

In this work, we present a theoretical study of a molecular junction based on benzene molecule at the center of the junction with three semi infinite graphene nanoribbons as external terminals to explore spin dependent current properties by using Green's function method. The exchange magnetic field is exerted on the molecular junction in order to break the degeneracy of electrons with spin up and spin down states. It is shown that by changing chemical potential and choosing a proper geometry of the structure we can control the direction of spin dependent electron current such that in one of the external terminals electrons with different spin states flow in opposite directions; therefore, in that terminal the pure spin current can be attainable. In addition, we show that by considering another form of benzene Y-shape junction and by readjusting chemical potentials of the external terminals, we can set the system in a way that a totally unpolarized incoming spin current split into spin up and spin down currents which transmit through different output terminals. In this case, the proposed system can be considered as a Stern-Gerlach device.

Tellurium nanoparticles have broad significant applications including treatment of infectious diseases, imaging, drug delivery systems, anti-inflammatory drug research, anti-inflammatory, anticoagulant drugs and treat many kinds of tumors. In the current study, potential of marine bacteria as biocatalysts were used for the biological reduction of tellurite oxyanion into to tellurium nanoparticles. The prepared tellurium nanoparticles were examined using UV-visible spectroscopy analysis, Energy dispersive x-ray spectroscopy EDS, Fourier-transform infrared spectroscopy FTIR and Scanning electron micrograph analysis. In this context, we isolated 13 tellurite-resistant bacteria were isolated using the enrichment technique. Among them, the strain TR2211 had a great potential for extracellular synthesis of tellurium nanoparticles. The isolated strain selected and characterized Brevibacillus sp. strain TR2211 GenBank accession number MK719235 based on phenotypic and molecular characteristics. Finally, the extracellular synthesis of tellurium nanoparticles was investigated under optimized reaction conditions. Our results show that the extracellular spherical-shaped tellurium nanoparticles with average size of 31 nm were formed in an optimal tellurite concentration of 1. 5 mM, optimal initial biomass concentration 40 g/l at the optimal pH 7. 5 and optimal temperature of 30ᵒ C after 120 h of incubation under resting cell conditions. This is the first report on biosynthesis of tellurium nanoparticles by Brevibacillus sp. strain TR2211.

Owing to the requirements of integrated circuits to the structures that guide light in the requisite directions and focus on appropriate sites, benefiting photonic crystal properties to achieve photonic crystal lenses is proposed. These lenses have the high capability of focus for modes at the nano-scale focal point, with low loss. In this paper, photonic crystal lenses are designed through etching air-holes in a hexagonal arrangement in SiO2 dielectric substrate. By applying plane waves to these different nanometer structures with a variety of arrangements and pitches and interaction of light with structure, thereby light is focused at desired points. The results of the simulations, including electric field amplitude, intensity, power, and focusing width were investigated using field profiles at the wavelength of the first telecommunication window (850 nm). The simulation results indicated that these parameters can be applied at a specified and optimal pitch value, 385 nm, for optimum control and concentration in lensing at small nano-scale dimensions within a fraction of wavelength, ~0. 49 µ m. Also, the result of the Sensitivity for applying the structure as an optical sensor is 645 nm/RIU.

In this study, the third order susceptibility of ZnS nanoparticles doped in nematic liquid crystal 5CB was evaluated. Firstly, ZnS nanoparticles was synthesized by hydrothermal method. Then this nanoparticles was added to nematic liquid crystal with 1%wt. After that, for calculating the third order susceptibility, linear and nonlinear absorption coefficients, linear and nonlinear refractive indices were achieved. The laser source in this study is He: Ne CW laser at 632. 8 nm wavelength. The initial arrangement of molecules is vertical status. The results showed that self-defocusing effect and two photon absorption nonlinear phenomena have happened in the sample. According to results, the nonlinear refractive index and nonlinear absorption coefficient of ZnS nanoparticles doped in nematic liquid crystal 5CB are 5 and 3 times more than the nonlinear refractive index and nonlinear absorption coefficient of pure nematic liquid crystal 5CB.

In this study, it was tried to prepare nanostructured thin films of Co-doped CdZnS (Co: CdZnS) with relative single dopant-related emission peak, through optimization of several experimental parameters, and using chemical bath deposition technique. Results demonstrated that the intense emission peak around 530 nm can be attributed to the recombination of charge carriers through mid-gap localized energy levels of cobalt ions. The Xray diffraction patterns of Co: CdZnS thin films, also revealed that increasing deposition temperature leads to an increase in the size of nanocrystals. The suitable quality of surface characteristics of the layer at each deposition temperature was demonstrated by field emission-scanning electron microscopy. The emission characteristics of these layers show their suitable applicable potentials as light-emitting structures in nanoscale optoelectronic devices.

In this research, ZnS nanostructure thin films with thicknesses of 130-210 nm were prepared on glass substrates at 70 by chemical bath deposition method. In this method, thioacetamide and triethylamine were used as a S-2 source and a completing agent instead of ammonia, respectively. The effect of changes in concentration ratio of thioacetamide to zinc as well as deposition time on structure, surface morphology, particle size, thickness and optical properties of the layers were examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and ultraviolet-visible (UV-vis. ) spectroscopy. UV-vis. spectroscopy data showed the prepared ZnS films to have more than 70% transmission in the visible region and an optical band gap ranging from 3. 75 to 4. 1 eV. XRD results revealed that the obtained films were highly crystalline with a cubic structure. FE-SEM images showed that the surface of the films was covered with homogenous, dense and fine spherical nanoparticles.

In this paper nanoparticles of titanium dioxide have been synthesized by sol-gel method. Effect of sol aging time as well as calcination temperature on physical and structural properties of the nanoparticles have been studied by thermal analysis (TG/DTA), x-ray diffraction (XRD), transmission electron microscope (TEM), and statistical analysis of particle size distribution. DTA thermal analysis of the sample shows three weight-loss regions. XRD analysis shows that samples have anatase phase up to 700 º C, but at 800 º C relative phase change to rutile can be seen and nanoparticles have mixed anatase and rutile phases. The samples calcined at 900 º C have pure rutile phase. The results show that by increasing the calcination temperature the size of nanoparticles has increased and the largest crystallite size for anatase phase is obtained 38. 7 nm and 147. 5 nm for rutile phase. Furthermore, aging time has no effect on the crystalline phase of samples. FTIR spectra of the samples indicate the formation of Ti-O and O-Ti-O bonds. Absorption peaks which are related to symmetric and asymmetric C=O bonds have been reduced after calcination and have been lost at higher temperatures. TEM image confirms the nanoparticles are spherical with 13. 2 nm average diameter.

In this study, the structural, electronic and magnetic properties of silicon carbide monolayer coated with manganese have been investigated. The results of the electrical properties show that, in contrast to graphene, the pristine SiC monolayer has a sizeable band-gap which makes it suitable for application in electronics industry. The most stable structure was identified by considering manganese atoms on carbon atoms, silicon atoms, and hexagon centers with doing the complete relaxations of atomic positions and cell parameters. The results of the calculations show that the most stable state of this compound is related to the case when manganese atoms are deposited on carbon atoms. Therefore, the electronic and magnetic properties are calculated for this structure. The partial and total density of states indicate the existence of half-metallicity in this compound. As a result, this monolayer can be used to make Nano spintronic components and spin valves. Also, in this paper, we tried to study the mechanism for the formation of half-metallic by plotting spin-dependent band structure diagrams and comparing them with the partial density of states.