فصلنامه نانو مقیاس
سال دهم شماره 2 (پیاپی 38، تابستان 1402)

In this study, structural studies, photoluminescence and thermoluminssence properties of CaZrO3 nanoparticles added with Ce3+ ion at different concentrations (x = 0.1-0.6 mol%) were investigated. Structural analysis of the samples was performed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The XRD pattern indicated the formation of a perovskite structure at 700 °C. The thermoluminssence (TL) properties of CaZrO3:xCe3+ nanophosphors were investigated at room temperature under X-ray at different times. Maximum TL intensity was obtained for Ca0.998Ce0.002ZrO3 samples. The sample of Ca0.998Ce0.002ZrO3 was exposed to X-ray at different time intervals from one to 15 minutes. As the irradiation time increases, the number of charge carrier increases, which results in an increase in the intensity of TL. Linearity, reproducibility and fading were also investigated for this sample, which is suitable for TL dosimetry due to its significant stability, low fading and linearity of the TL response. Study of photoluminescence (PL) behavior at room temperature showed when the phosphors were excited by light with a wavelength of 253 nm, three emission peaks at 404, 425 and 488 nm were obtained, respectively. By increasing Ce concentration, the emission peaks in PL spectra slightly shift from violet region to blue region.

Nano-sized of a copper (II) coordination polymer [Cu3(L)(NO3)4(H2O)4]n (1) {H2L=[2,6-bis(pyridine-2-ylmethylidene) hydrazinocabonyl] pyridine} compound was synthesized by sonochemistry method. To study the influence of solvent and concentrations of initial reagents on the nano-sized compound (1) certain test was designed and six samples of 1 were prepared through the sonochemical irradiation process. Polar solvent led to smaller and uniform nanostructure particle morphology. To prepare copper (II) oxide nano-sized by calcination specimen of 1 was used as a precursor. The structure and morphology of nanoparticles are characterized by using scanning electron microscopy (SEM), x-ray powder diffraction (XRD) and IR spectroscopy. The thermal stability of nano compound 1 was studied by thermal gravimetric (TGA) and differential thermal analyses (DTA). In order to study the optical behavior of the prepared compound 1 as nanoparticle and bulk form the UV-Vis absorption spectral along with photoluminescence was carried. Hirshfeld surface analysis and two-dimensional fingerprint plots were used to analyze the intermolecular interactions, indicating that the most important contributions for the crystal packing are from O…H/H…O (31.7%), H…H (14.6%), C…C (6.5%), N…O (3.8%) and N…H/H…N (3.8%).

In this study, a novel system of artesunate polymer based nanocarrier has been produced and characterized. The drug was grafted on the surface of the polyamidoamine dendrimer, then by cross-linking with ethylene glycol dimethyl acrylate, the polymer based nanocarrier was prepared. Then the prepared sample was analyzed by nuclear magnetic resonance spectroscopy (1HNMR), ultraviolet-visible spectrometer (UV-vis), and the scanning electron microscope (SEM). The results confirmed that the prepared nanocarrier has high water solubility, low density, the ability to load a large amount of drug, and sustained release. After pH dependent nanodrug degradation artesunate controlled released from the polymer network. According to the prolonged release time, the drug remains stable in the cellular environment. On the other hand, since drug release is pH dependent, by changing the pH in different environments, the amount of drug release can be controlled, this properties is one of the characteristics of targeted drug delivery, and effectively and significantly, the efficiency of this nanopolymer will be suitable for artesunate drug delivery.

In this work, Cu2S nanoflowers, which is a non-toxic p-type semiconductor and has an indirect band gap of 1.21 eV, were synthesized by solvothermal method and characterized through XRD and FESEM analyses. Then, their optical properties were measured through UV-Vis, FT-IR and PL analyses. Also, the photothermal properties of these nanoflowers were investigated in the range of visible and near infrared light. The results showed that these nanoflowers have good photothermal properties in both visible and infrared light ranges. In the visible region, by irradiating a water solution containing 20 g/l of Cu2S, a temperature increase of 23 °C was observed during 60 min. and in the infrared region, with 808 nm laser radiation, a 44 °C increase was observed for a concentration of 10 g/l of Cu2S. Also, surface evaporation of water in the presence of these nanoflowers was investigated with visible light irradiation and showed that the water evaporation increases up to 4 times with increasing the concentration of these nanoflowers

Radiative detectors and devices operating in the range (0.2-10) terahertz and room temperature are needed. The need is created by fast advances of the science and terahertz technologies in the domain of astronomy to biosecurity. By the advances of molecular beam epitaxy (MBE) the growth of semiconductor superlattices of the order of 100 A° is performed. This lattice constant is big and could reveal high field non-ohmic behaviors. The negative differential conductivity (NDC) arises from the grate numbers of electrons in the proximity edge of miniband boundary. The velocity of electrons approaching to the miniband is reduced, causing the NDC effect. In this article the NDC in semiconductor superlattices for sinusoidal and periodic square -well potentials was studied. The extracted maximum carrier drift velocities for a superlattice semiconductor were nearly 1.8x105 m/s and 2.6x105 m/s respectively and the obtained ratio of maximum drift velocity to the corresponding minimum was more than 3 for the two potentials. Also the NDC in semiconductor superlattices for parabolic and sinusoidal dispersion equations at different frequencies was investigated. In the parabolic dispersion equation, near the harmonic Bloch oscillations at frequencies between even and odd harmonic oscillations, the high frequency NDC was observed.

In this article, the electronic, structural and magnetic properties of hydrogenated graphene nanoribbons with zigzag-shaped edges (ZGNR-H) and armchair-shaped edges (AGNR-H) have been investigated using density functional theory (DFT). The spin density of states and band structure have been calculated for ZGNR-H and AGNR-H nanoribbons with different widths. The results show that the electronic and magnetic properties of graphene nanoribbons are strongly dependent on the width of the ribbon and the shape of the edge of the ribbon, which is zigzag or armchair. So that the hydrogenated armchair ribbons are all non-magnetic semiconductors and with the increase in the width of the ribbon, there is a periodic and decreasing bandgap trend. While zigzag hydrogenated graphene nanoribbons with different widths are all magnetic metal and the values of magnetic moment for ZGNR-H nanoribbons increase with increasing of ribbon widths.

Many researchers have reported the synthesis of metal nanoparticles by plant extracts and their potential applications. Cherry tree leaf extract is one of the effective materials in the synthesis of AgNPs, which is confirmed by the results of FTIR analysis. Did AgNPs according to the design of the experiment carried out by the Mixture Design method by mixing three regenerating substances (cherry tree leaves 0-3 ml), basic salt substance (1 mM solution of AgNO3 5-9 ml) and stabilizing agent (AloeVera gel) (0-1 ml) was synthesized by green method. After the optimization, the results showed that the amounts of 2.51, 5.79 and 0.69 mL respectively for reducing agent, basic solution and stabilizing agent were the most suitable mode of synthesis of nanoparticles, and in this mode, the highest concentration of 16.88 ppm, the lowest average particle size of 36 nm, the most appropriate PDI of 0.43 and the highest zeta potential of 25 mV will be obtained. The properties of synthesized AgNPs were evaluated in optimal conditions and the results of UV-Vis and DLS analyzes confirmed the obtained results with slight differences. AgNPs showed good antioxidant properties of 28.45% and antibacterial properties against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Antifungal properties were also found to be 65.55%.