فصلنامه نانو مقیاس
سال هشتم شماره 3 (پیاپی 31، پاییز 1400)

In this research, a preliminarily stable sol of titanium dioxide was synthesized by the addition of acetic acid as a promoter in order to increase the yield of TiO2 synthesis. The formation of active anatase phase was confirmed by X-ray powder diffraction analysis and the crystal size of 10–22 nm was obtained. The specific surface area found to be 93.65 m2/g for the synthesized samples. Hereafter, the synthesized TiO2 sols were coated, as a thin layer of nanostructured TiO2, on the surface of ceramic via the cold spray method. The contact angle measurement of the coated surfaces exhibited that the use of these coatings has led to the formation of super-hydrophilic surfaces. Eventually, the photocatalytic activity of the coated samples was examined by the degradation of formic acid under the visible light. It was shown that the calcination of coated surfaces can improve the photocatalytic activity of the coated samples. Consequently, the use of acid acetic as a promoter in the synthesis of TiO2 nanoparticles can significantly improve the photocatalytic properties.

In this work the possibility of removing lead metal ion with Fe3O4 magnetic nano particles from aquent samples and measuring the remained solution was investigated. Chitoson was used for this purpose. Chitosan is a hyphophilic and cationic polymer that obtained from removing acetil citin in basic solutions and use as an absorptive to removing heavy metals. The experiments of this investigate was carried out in discrete system and room temperature. pH, commence concentration of metal, time were optimized by experimental design. The optimum condition for pH, the amount of sorbent, commence concentration of metal and time were 4.14, 0.06 g, 60 mg L-1 and 66 min respectively. Recover of sorbent by EDTA and multi usages are important merit of this sorbent.

Logic gates based on optical waveguides have been implemented in recent years. But the use of the plasmonic effect on logical devices like semiconductor has not yet been investigated. The graphene-based plasmonic effect is a novel effect that is discussed in this paper on nanostructure devices such as semiconductor. In this paper, a logical innovation for the design of the logical gates AND and XOR has been implemented as the basic components for the half adder circuit based on graphene plasmonic waveguides. The functions for the graphene are computed by the equations and charts defined in the articles and applied to the system. By applying the environmental parameters, the conductivity value at the chemical potential of 0.565 ev is obtained according to the conductivity equation of 0.936 × 10-4. Due to the constant value of the permeability of the vacuum, which is equal to one and the graphene thickness is equal to 0.7 nm, the amount of the dynamic part of the dielectric coefficient at the 7 Grad / s work frequency is the approximate value of 0.02. The wavelength of the input signal is 1.55 μm in the chemical potential of 0.565 ev. After applying the defined parameters of graphene under the plasmonic waveguide for the desired structure, there are good results for responding to the logical structures in half adder circuit. The first designed device is a graphene-based AND plasmon structure. The power factor of this switch is 0.98 for optimum on state and 0.55 for off state. Then the structure of XOR is designed, whose power factor of this switch in optimal conditions is 0.85 for on state and 0.02 for off mode, which a in comparison with previous works, have maximum power transfer characteristics in the half adder circuit.

In this study, nickel phosphide nanostructure was fabricated by hydrothermal method using nickel chloride and red phosphorus precursors. The prepared sample was characterized by using XRD, FESEM and UV-Vis absorption analysis. The results showed that the sample has a bi-phase Ni2P / Ni12P5 crystal structure and has a spherical nanoparticle morphology. Then, the effect of different concentrations of catalyst (20 ppm, 100 ppm, 200 ppm, and 1000 ppm) on methylene blue degradation under UV light irradiation, without any other additive, was investigated. It was found that catalyst with a concentration of 100 ppm had the highest degradation value. By further increase of the catalyst concentration in the solution, the degradation rate decreases due to an increase in the opacity of the suspension and agglomeration of nanoparticles at high concentrations.

Magnetic fluid hyperthermia is a new subclass of cancer treatment in which super-paramagnetic nanoparticles injected or diffused in cancerous tissue while exposing alternating magnetic field. The aim of this study is to scrutinize the effects of nanoparticles’concentration, resonance frequency, the coil’s resonance frequency and time as well as the magnetic field intensity on A-549 human lung cancer line.In this study, after culturing A-549 human lung cancer line, the four different nanoparticles’ diameters at three different frequencies, three different magnetic field intensities and four concentrations of nanoparticles were arranged to study the importance of them whilst a series of the three coils was designed to produce magneticHaving weighed the importance of parameters including the resonance coil’s frequency, nanoparticles’ resonance frequency and sizes, nanoparticles concentrations, the magnetic field intensity and iron uptake of cell line, we are inclined to believe that these parameters play a pivotal role in the hyperthermic temperature difference whilst this temperature difference equal to 5±0.5 0C can able to kill al cancerous A-549 cells.

In this paper, electronic properties of nano-sheets of silicon carbide, germanium carbide and tin carbide have been investigated. The calculations were performed based on the density functional theory (DFT) using full potential augmented plane wave (FP-LAPW) method. In our calculation we used GGA, LDA and TB-mBJ approximations for the exchange-correlation potential. Density of states calculations shows that the carbon p-orbitals have the highest contribution to the conducting and valance bands in the three nano-sheets. The band structure calculations show that the band gap in SiC, GeC and SnC nano-sheets is direct, direct and indirect, respectively. The band gaps calculated by the TB-mBJ approximation for these nano-sheets were obtained about 3.31, 2.93 and 1.38 eV, respectivly, which are significantly higher than the band gap calculated by the two other approximations. Therefore, due to the direct and relatively large energy bands, SiC and GeC nano-sheets can be considered in the nano electro-optic devices. The percentage of ionization of the bonds was investigated using Pauli's relation and electron density calculations. The results show that the type of the bonds is covalent and the percentage of ionization of the bonds in the SiC, GeC and SnC are 10, 7 and 8 percent, respectively.

A novel nanosensor based on CdSe quantum dots was developed for the detection of lead ions in aqueous solution. Synthesized nanosensor exhibited high selectivity and sensitivity for the detection of lead ions at very low concentration. Fluorescence emission of nanosensor was increased linearly within 0-500 μM concentration of Pb2+ ions. In order to synthesize nanosensor, the thioglycolic acid capped CdSe quantum dots were synthesized using Cd2+ and freshly prepared Se2- ions in the presence of thioglycolic acid, which then functionalized with ethylene diamine using EDC/NHS coupling reagent, and then reacting with fluorescein methyl ester. The structure of prepared nanosensor was characterized and confirmed using UV-Vis, Ft-IR, SEM, TEM and EDX analysis.

Fe84P16 nanowires were fabricated by AC electrodeposition method at various frequencies (50-1000Hz) into 1000Hz) into anodic oxide (AAO) templates. The AAO templates are prepared by a two-step anodizing process. The synthesized nanowires were analyzed using alternating gradient force magnetometer (AGFM), scanning electronic microscope (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). The effect of deposition frequency and thermal annealing on magnetic properties and structural of nanowires were investigated. The STM image indicated that the diameter of nanowires is between 30-50 nm. The XRD pattern shows that the crystalline structure of nanowires is bbc. The magnetic properties (coercivity field and squareness) of samples were measured by alternative gradient force magnetic (AGFM). The effect of frequency on magnetic properties of nanowires exhibits that the highest coercivity (1149Oe) obtained for nanowires prepared at 200 Hz and also the squareness of nanowires increased by increasing of electrodeposition frequency. For studying the effect of annealing on the magnetic properties of nanowires, all nanowires were annealed at temperature range (300- 600 oC). The results show that the crystallinity of nanowires increases after annealing and consequently the magnetic properties are improved.

The phase diagrams of the anisotropic three-layer Ising model on the square lattice with diluted surfaces have been constructed with high precision, using the probabilistic cellular automata with the Glauber algorithm. The thermal variation of magnetization is calculated for different values of nearest neighbor couplings: namely J ≠  Js  ≠  J1, where J and Js  are the nearest neighbor  couplings within inner-layer and surface-layer, respectively, and each magnetic site in the surface-layer is coupled with the nearest site in the inner-layer via the exchange interaction J1. In the case of the antiferromagnetic coupling between layers, simulation results show existence of the compensation point in the phase diagram.

In this study, the nitrogen-doped carbon quantum dots were synthesized via microwave method using citric acid and urea precursors in a homogeneous aqueous solution. A centrifuge machine was used to eliminate large particles from the samples and to sort nanosized particles with variable centrifugal forces. X-ray diffraction pattern was obtained in order to study the formation of crystalline structure type of the sample and the size of crystallite. The broadening of peak indicated the nanosized formation of synthesized particles. Optical properties of the samples were examined by ultraviolet-visible and photoluminescence spectrometers. The absorption peaks wavelengths depended on particle sizes and had blue shift by decreasing of particle sizes. The Tauc plot indicated that energy gap increased from 2.39 eV to 2.62 eV with decreasing particle size. Emission peaks of nitrogen-doped carbon quantum dots, under the excitation of ultraviolet light, had fluorescence radiations in the visible spectral region of the green-blue.

Organic photovoltaic cells (OPV) have an active part that is inclusive two parts; electron donor and electron receptor. In this work, Polyhexyl thiophene (P3HT) polymer is considered as an electron donor and some cyclopentene and cyclohexene derivatives of C60 and C20 nanofullerens as electron receptors, that using Gaussian 09 software and density functional theory (DFT) at B3LYP/6-31G (d, p) level are evaluated. After optimization of the structures, the contribution of s and p orbitals and also, energy resonance  π→π* in molecules, some of quantum descriptors such as HOMO and LUMO energy, energy gap (Eg), chemical potential (μ), chemical hardness (η), electrophilicity index (ω) and maximum charge transfer (∆Nmax) were performed. The value of the open circuit voltage (Voc), which is one of the most important parameters indicating efficiency of a solar cell (η), was obtained for the studied molecules with Gaussian outputs. Results show that cyclopentene and cyclohexane derivatives of C60 and C20 nanofullerens can have be desired efficiency as receptors in photovoltaic cells. However, the cyclopentene derivatives will be more effective than cyclohexene derivatives in solar cells.

The nano silver particles has been attractive the large number of researchers. These properties are due to the very high volume ratio of these particles. Although there are different methods have been offered for the synthesis of nano particles of silver but the chemical recovery method because of the simplicity and ability to control and particle's size is the most common methods to product nano particles. In this research the effect of silver disinfection in water has been investigated. The silver particles are produced with using silver nitrate and sodium citrate and then the polyamide is coated on the polymer and used as absorbent filter. Morphology was determined by absorbing the surface and the shape and size of nano particles with an electron microscope and also it the same about the present of silver in the polymer after coating with an X-ray diffraction device (EDAX). The nutrient agar is used for investigate of the effect of nano silver disinfection in water pollution (Escherichia coli) from the general culture medium and also the effects of changing of power hydrogen (pH) temperatures and duration of contact required for disinfection water studied.

The main objective of this study is Vanadium ion removal from industrial wastewater by Magnesium Oxide/chitosan nanocomposite and also, the investigation the optimal conditions of pH, agitation time, adsorbent dose and temperature. Morphology of Chitosan/ magnesium oxide nanocomposite and nanoparticle size and its distribution were studied by FTIR, XRD and FESEM, respectively. The adsorption studies performed in a batch system and the effect of various operating parameters such as solution pH (2-11), agitation time (15-300 min), adsorbent dose (1-6 mg/100ml) and initial concentration of Vanadium (5-30 ppm) was investigated. Freundlich isotherm (R2=0.97) displayed a better fitting model than Langmuir isotherm. The adsorption kinetics results showed that nanocomposite adsorption process was well-described by pseudo-second-order kinetic model. Thermodynamic parameters of adsorption process such as enthalpy, entropy and Gibbs free energy were also calculated that their values obtained 2.85 Kj/mol, 0.0019 Kj/mol.K and -4.03Kj/mol, respectively. The results of this study showed that Chitosan/ magnesium oxide nanocomposite is a suitable adsorbent for the adsorption of vanadium.

Plasmon-polaritons can confine an optical wave to a region with dimensions much smaller than the wavelength of the wave in free space. This increases the interaction of optical radiation with material that is suitable for sensing applications. For this reason, in this paper plasmon-polaritons in a nanolayer graphene at mid infrared spectral wavelengths are investigated. Owing to the large wavenumber of plasmon-polaritons in graphene relative to the wavenumber of an optical wave with the same frequency in free space, diffraction grating is used for exciting plasmon-polaritons in graphene. For investigating the effect of relaxation time on the plasmon-polaritons in graphene, relaxation time was varied from  to  and plasmon-polaritons in graphene were simulated by solving electromagnetic wave equation. The results show that while the variation of relaxation time does not affect the period of plasmon-polaritons in graphene, with the decrease of relaxation time confinement and intensity of the plasmon-polaritons in graphene decrease. In addition investigating the reflectance, transmittance and absorption spectra show that the intensity and the location of pick points in the reflection spectra are appropriate for qualitative determination of confinement, and quantitative determination of excitation wavelength of plasmon-polaritons in graphene.