narges nikoofard

Due to the unique physical and chemical properties of two-dimensional (2D) materials, such as linear band structure near the Fermi level, high electrical and thermal conductivity, they have opened up a wide vision in the fabrication of nanoelectronic devices, energy storage and information transmission. One of the theses materials that has recently received attention is a two-dimensional monolayer of boron atoms called borophene which has various allotropes such as α, β12, χ3, 2-pmmn and 8-pmmn. This 2D material has tilted and anisotropic Dirac cone and in addition to excellent transparency, it has excellent electron and ion conductivity. These properties along with other properties of borophene have caused diverse and potential applications of this material in gas sensors, metal ion batteries and electronic and optoelectronic devices. In this paper, we intend to review the properties of borophene and investigate the effect of factors such as impurity, light radiation, strain, dimension reduction in the form of nanoribbon, temperature, electric and magnetic fields on the properties of electron transport in this material.

The fast spread of COVID-19 in the world has raised as a serious threat for human health and global economy and is considered as a new challenge in medicine. In this paper, complete information is presented about treatment of viruses with the aid of nano-particles via attachment to the virus, release of reactive oxygen species, or destructive ions. In the present paper, present and potential applications of nano-technology to deal with viruses are reviewed, in the synthesis of various nano-based materials such as nano-delivery systems for treatment, personal protective equipment, and diagnostic devices. Here, the role of nano-materials in drug delivery is similar to other fields in nano-medicine; however, their intrinsic accumulation in macrophages is favorable for COVID-19. Nano-materials can be used in masks for longer usage times or air filters to ensure more protection. The new nano-based diagnostics are faster and sometimes more accurate than the traditional PCR method. The discussed nano-particle based methods for COVID-19 can also be considered for new viruses that will appear in future.

Advances in nano-fabrication techniques have enabled confinement of polymers at nano-scale cavities. This has raised a higher demand for development of theories for polymers in severe confinements. In this manuscript, the escape of a polymer confined in a nano-slit through a nano-pore in the strong confinement regime is investigated, theoretically and by using Langevin Dynamics (LD) simulations. The strong confinement occurs when the height of the nano-slit becomes smaller than the persistence length of the polymer. Persistence length is a measure of the polymer stiffness. The radius of gyrations R_g, the confinement force on the polymer f, and the ejection time of the polymer τ are obtained in different values of the polymer length L, the height of the nano-slit D, and the persistence length of the polymer P. The simulation results are well described with the scaling relations R_g/L^0.75 ~(P/D)^0.25 and f/L~(PD^5 )^(-0.4) and τ/L^2 ~(PD^2 )^0.42, respectively. The simulation results are in rather good agreement with the theory. It seems that the relative difference between theory and simulations is due to being close to the transition region between weak and strong confinement regimes.

Block copolymer nano-micelles are especially important in cancer treatment because of their fine dimensions. In this article, three systems of amphiphilic copolymers with similar lengths and different ratios of the hydrophobic and hydrophilic chains are studied using implicit-solvent coarse-grained molecular dynamics simulations. The factor fphil is defined as the ratio of the number of hydrophilic monomers to the total number of monomers. Three different values are examined fphil = 0.65, fphil = 0.55 and fphil = 0.40. The time evolution and the final shape of the assembled nano-structures are investigated. The shapes of the nano-micelles are symmetric in the two larger hydrophilic ratios. However, the nano-micelle becomes asymmetric in the one smaller hydrophilic ratio. The average diameters of the whole nano-micelle and its hydrophobic core are calculated. These diameters are obtained by direct calculation from the particles coordinates and by using the radial distribution functions. The sizes of the nano-micelles and their stabilities increase considerably with decreasing the length of the hydrophilic chain. Correspondence of the results on the geometry, size and stability of the nano-micelles with the experimental findings is discussed.