Sharif Digital Repository

Controlling evaporation plays an essential role in arid and semi-arid water resources systems where it accounts for a considerable amount of reservoirs outflow. In this study, we have evaluated evaporation reduction efficiency of different kinds of self-assembled nano-thickness films. The films consist of six different combinations of stearyl and cetyl alcohols with additives such as jojoba oil, stearic acid, and calcium hydroxide. The study lasted from July to August and utilized two pairs of class A evaporation pans: one pair was semi-floating on Chitgar lake water surface while the other one was located on the shore. The experimental results showed that a monolayer containing 3:1 stearyl... 

Recently, huge attention has been drawn to improve optical sensing devices based on photonic resonators in the presence of graphene. In this paper, based on the transfer matrix approach and TE polarization of the incident electromagnetic waves, we numerically evaluate the transmission and reflection spectra for one-dimensional photonic resonators and surface plasmon resonances with strained graphene, respectively. We proved that a relatively small strain field in graphene can modulate linearly polarized resonant modes within the photonic bandgap of the defective crystal. Moreover, we study the strain effects on the surface plasmon resonances created by the evanescent wave technique at the... 

Very recently, two-dimensional (2D) iodinene, a novel layered and buckled structure has been successfully fabricated (Qian et al 2020 Adv. Mater. 32 2004835). Motivated by this latest experimental accomplishment, for the first time we conduct density functional theory, first-principles calculations to explore the structural, electronic, and optical properties of monolayer, few-layer and bulk iodinene. Unlike the majority of monoelemental 2D lattices, iodinene is predicted to be an intrinsic semiconductor. On the basis of calculations using the generalized gradient approximation of Perdew-Burke-Ernzerhof for the exchange-correlation functional and the Heyd-Scuseria-Ernzerhof (HSE06)... 

An economical epichlorohydrin cross-linked chitosan @ magnetic Fe3O4/activated carbon nanocomposite, CH-EP@Fe3O4/AC, was successfully synthesized and used as a suitable adsorbent material for removal of a triphenylmethane cationic dye, Malachite green (MG), an anionic dye, Reactive red 120 (RR120), and Mercury ions (Hg2+) from aqueous solution. The prepared adsorbent has been characterized with Fourier transform infrared spectroscopy, X-ray diffraction, Scanning electron microscopy, Thermogravimetric analysis, Brunauer–Emmett–Teller analysis as well as Vibrating sample magnetometer. According to the result of Brunauer–Emmett–Teller isotherm, the prepared adsorbent has a specific surface area... 

We report on charge transport across self-assembled monolayers (SAMs) of short tau peptides by probing the electron tunneling rates and quantum mechanical simulation. We measured the electron tunneling rates across SAMs of carboxyl-terminated linker molecules (C6H12O2S) and short cis-tau (CT) and trans-tau (TT) peptides, supported on template-stripped gold (AuTS) bottom electrode, with Eutectic Gallium-Indium (EGaIn)(EGaIn) top electrode. Measurements of the current density across thousands of AuTS/linker/tau//Ga2O3/EGaIn single-molecule junctions show that the tunneling current across CT peptide is one order of magnitude lower than that of TT peptide. Quantum mechanical simulation... 

The fabrication of the C6N7 monolayer [Zhao et al., Sci. Bull. 66, 1764 (2021)] motivated us to discover the optical, structural, mechanical, and electronic properties of the C6N7 monolayer by employing the density functional theory (DFT) method. We find that the shear modulus and Young's modulus of the C6N7 monolayer are smaller than the relevant values of graphene. However, Poisson's ratio is more significant than that of graphene. Applying the PBE (HSE06) functional bandgap of the C6N7 monolayer is 1.2 (1.97) eV, and the electronic dispersion is almost isotropic around the Γ point. C6N7 is more active in the ultraviolet region as compared to the visible light region. This study provides... 

We theoretically investigate the magnetoelastic coupling (MEC) and its effect on magnon transport in two-dimensional antiferromagnets with a honeycomb lattice. MEC coefficients along with magnetic exchange parameters and spring constants are computed for monolayers of transition-metal trichalcogenides with Néel magnetic order (MnPS3 and VPS3) and zigzag order (CrSiTe3, NiPS3, and NiPSe3) by ab initio calculations. Using these parameters, we predict that the spin-Nernst coefficient is significantly enhanced due to magnetoelastic coupling. Our study shows that although Dzyaloshinskii-Moriya interaction can produce spin-Nernst effect in these materials, other mechanisms such as magnon-phonon... 

We investigate systematically the spin-Nernst effect in Néel and zigzag ordered honeycomb antiferromagnets. Monolayers of transition-metal trichalcogenides, MnPSe3, MnPS3, and VPS3 show an antiferromagnetic Néel order while CrSiTe3, NiPS3, and NiPSe3 show an antiferromagnetic zigzag order. We extract the exchange and Dzyaloshinskii-Moriya interaction parameters from ab initio calculations. Using these parameters, we predict that the spin-Nernst coefficient is at least two orders of magnitude larger in zigzag compared to the Néel ordered antiferromagnets. We find that this enhancement relies on the large band splitting due to the symmetry of magnetic configuration in the zigzag order. Our... 

To improve the efficiency of electrochemical processes for environmental remediation, we present a new type of hybrid nanomaterials based on leaf-like copper-based quaternary transition metals and spongy monolayer graphene. To demonstrate the functionality of the hybrid electrocatalyst, fast and competent electrooxidation of water and glucose is shown. The mechanism of improved catalysis is ascribed to the synergetic catalytic effect of quaternary Cu-Ni-Fe-Co alloy with dendritic morphology along with the highly conductive and spongy structure of the graphene monolayer. It is shown that water oxidation can be performed at a low overpotential of 315 mV to reach a current denisty of 100 mA... 

Van der Waals (vdW) heterostructures of two-dimensional monolayers are a relatively new class of materials with highly tunable band alignment, bandgap energy, and bandgap transition type. In this study, we performed density functional theory calculations to investigate how a vdW heterostructure of heptazine-based graphitic carbon nitride (hg-C3N4) and graphitic zinc oxide (g-ZnO) monolayers is formed (hg-C3N4/g-ZnO). This heterostructure is a potential solar-driven photocatalyst for the water-splitting reaction. Upon the formation of the heterostructure, a type-I indirect bandgap (Eg = 2.08 eV) is created with appropriate conduction band minimum and valence band maximum levels relative to... 

Single-layer MoS2-MoO3-x heterojunction nanosheets with visible-light-sensitive band gap energy and average lateral dimensions of ~70 nm were synthesized by using a two-step combined exfoliation method. The exfoliation was initiated from pristine MoS2, while some sulfur sites in expanded MoS2 sheets during exfoliating were substituted by ambient non-thermal oxygen, resulting in formation of α-MoO3-x crystalline domains. The morphological features, crystalline structure, phase formation, number of layers, and optical properties of the MoS2-MoO3-x nanosheets were determined by atomic force microscopy; X-ray diffraction; field emission electron microscopy; transmission electron microscopy; and... 

In this article, the synthesis, characterization, and cyclic voltammetry (CV) measurements are reported for ferrocene-terminated oligophenyleneimine (OPI_Fc) and ferrocene-terminated conjugation-broken oligophenyleneimine (CB-OPI_Fc) self-assembled monolayers (SAMs) in two different electrolytes, namely, 1-ethyl-3-methylimidazolium-bis (trifluoromethyl-sulfonyl) imide (EMITFSI) ionic liquid and tetrabutylammonium hexafluorophosphate (Bu4NPF6) in acetonitrile (0.1 M solution). The SAMs were synthesized on Au surfaces by the sequential imine condensation reactions. CV was used to investigate the kinetics of electron transfer (ET) to the ferrocene, and it was observed that the standard ET rate... 

La-MOF-NH2@Fe3O4 (magnetic-MOF) was used as an efficient, ultrafast, and selective adsorbent for the separation of Congo Red (CR) with 92.02% removal after 2 min. The magnetic-MOF was identified by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) surface area, Zeta Potential analysis, analysis of the magnetic hysteresis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). Kinetics, isotherms, the effect of pH, thermodynamic, and selectivity of CR adsorption were investigated. The results confirmed that the adsorption kinetics complied with the pseudo-second-order model. The... 

The interactions between four different gas molecules (methanol, o-xylene, p-xylene and m-xylene) and Ni-decorated monolayer MoS2 were investigated by means of density functional computations to exploit its potential application as a gas sensor. The electronic properties of the Ni-decorated monolayer MoS2 and gas molecule (adsorbent–adsorbate properties) strongly depend on the Ni-decorated monolayer MoS2 structure and the molecular configuration of the adsorbate. The adsorption properties of volatile organic compound (VOC) molecules on Ni-decorated MoS2 has been studied taking into account the parameters such as adsorption energy, energy bandgap, density of states, and Mulliken charge... 

Density functional theory (DFT) calculations have been performed to investigate the electronic structure and photocatalytic activity of a hybrid Ag3PO4(111)/g-C3N4 structure. Due to Ag(d) and O(p) states forming the upper part of the valence band and C(p), N(p), and Ag(s) the lower part of the conduction band, the band gap of the hybrid material is reduced from 2.75 eV for Ag3PO4(111) and 3.13 eV for monolayer of g-C3N4 to about 2.52 eV, enhancing the photocatalytic activity of the Ag3PO4(111) surface and g-C3N4 sheet in the visible region. We have also investigated possible reaction pathways for photocatalytic CO2 reduction on the Ag3PO4(111)/g-C3N4 nanocomposite to determine the most... 

Several evidences support the idea that a small population of tumour cells representing self-renewal potential are involved in initiation, maintenance, metastasis, and outcomes of cancer therapy. Elucidation of microRNAs/genes regulatory networks activated in cancer stem cells (CSCs) is necessary for the identification of new targets for cancer therapy. The aim of the present study was to predict the miRNAs pattern, which can target both metastasis and self-renewal pathways using integration of literature and data mining. For this purpose, mammospheres derived from MCF-7, MDA-MB231, and MDA-MB468 were used as breast CSCs model. They had higher migration, invasion, and colony formation... 

Hydrostatic pressure is one of the most fundamental and common mechanical stimuli in the body, playing a critical role in the homeostasis of all organ systems. Kidney function is affected by high blood pressure, namely hypertension, by the increased pressure acting on the glomerular capillary walls. This general effect of hypertension is diagnosed as a chronic disease, but underlying mechanistic causes are still not well understood. This paper reports a portable and adaptive device for studying the effects of hydrostatic pressure on a monolayer of cells. The fabricated device fits within a conventional incubation system and microscope. The effects of various pressures and durations were... 

Controlled growth of atomic monolayers of IV-VII transition metal dichalcogenides (TMDs) has provided unprecedented opportunities to fabricate modern optoelectronic nanodevices. However, synthesis of large-area and high quality two-dimensional TMDs is still challenging. We have synthesized WS2 and MoS2 nanosheets by atmospheric pressure chemical vapor deposition (APCVD) at wide-range of processing conditions. The nanostructures were analyzed by optical and confocal microscopy, atomic force microscopy, Raman spectroscopy, and X-ray diffraction to determine the thickness, lateral size and structure of the deposits. Through designing and performing of a set of controlled experiments as well as... 

We study topological phase transitions and topological quantum field effect transistor in monolayer molybdenum disulfide (MoS2) using a two-band Hamiltonian model. Without considering the quadratic (q 2) diagonal term in the Hamiltonian, we show that the phase diagram includes quantum anomalous Hall effect, quantum spin Hall effect, and spin quantum anomalous Hall effect regions such that the topological Kirchhoff law is satisfied in the plane. By considering the q 2 diagonal term and including one valley, it is shown that MoS2 has a non-Trivial topology, and the valley Chern number is non-zero for each spin. We show that the wave function is (is not) localized at the edges when the q 2... 

The Ni-P/Zn-Ni compositionally modulated multilayer coatings CMMCs were electrodeposited from a single bath by switching the deposition current density. The corrosion resistance of the deposits was studied and compared with that of monolayers of Ni-P and Zn-Ni alloys via Tafel polarization, EIS and salt spray tests. Characterization of corrosion products by means of EDS and XRD revealed more details from the corrosion mechanism of the monolayers and multilayers. The corrosion current density of Ni-P/Zn-Ni CMMCs were around one tenth of Zn-Ni monolayer. The CMMC with incomplete layers performed lower polarization resistance and higher corrosion current density compared to the CMMC with...