Sharif Digital Repository

The inhibition effects of 3.5 bis (2-pyridil) 4-amino 1,2,4 triazole (NBTA) and 1-10 phenantrolin (PHEN), on corrosion of mild steel in acid solutions, (sulphuric acid and hydrochloric acid) were studied. The Tafel polarisation and ac impedance techniques were employed. Results obtained reveal that both compounds are relatively good inhibitors. The inhibition efficiencies of NBTA are higher in hydrochloric acid than in sulphuric acid. This has been attributed to the synergistic effect of chloride ions present in hydrochloric acid. The mechanism of inhibition of PHEN is believed to be owing to the formation of insoluble chelates between the organic molecules and atom/ion on the metal surface.... 

Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was... 

Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was... 

This paper deals with the study of the small scale effect on the pull-in instability of nano-switches subjected to electrostatic and intermolecular forces. Using Eringen's nonlocal elasticity theory, the nonlocal Euler-Bernoulli beam model is derived through virtual displacement principle. The static governing equation which is extremely nonlinear due to the intermolecular and electrostatic attraction forces is solved numerically by differential quadrature method. The accuracy of the present method is verified by comparing the obtained results with the finite difference method and those in the literatures and very good agreement is obtained. Finally a comprehensive study is carried out to... 

The graphene-based materials with unique, versatile, and tunable properties have brought new opportunities for the leading edge of advanced nanobiotechnology. In this regard, the use of graphene in gene delivery applications is still at early stages. In this study, we successfully designed a new complex of carboxylated-graphene (G-COOH) with ethidium bromide (EtBr) and used it as a nanovector for efficient gene delivery into the AGS cells. G-COOH, with carboxyl functions on its surface, in the presence of EtBr, formaldehyde, and cyclohexylisocyanide were participated in Ugi four component reaction to fabricate a stable amphiphilic graphene-EtBr (AG-EtBr) composite. The coupling reaction was... 

Mesoscopic hydrodynamic equations are solved to investigate the dynamics of nanodroplets positioned near a topographic step of the supporting substrate. Our results show that the dynamics depends on the characteristic length scales of the system given by the height of the step and the size of the nanodroplets as well as on the constituting substances of both the nanodroplets and the substrate. The lateral motion of nanodroplets far from the step can be described well in terms of a power law of the distance from the step. In general the direction of motion depends on the details of the effective laterally varying intermolecular forces. But for nanodroplets positioned far from the step it is... 

The application of a hybrid Cu(tpa).GO (Cu(tpa) copper terephthalate metal organic framework, GO graphene oxide) composite as a new adsorbent for the removal of toxic metal ions was reported. New hybrid nanocomposite with excellent dispersibility and stability was successfully fabricated by the simple and effective ultrasonication method. The synthesized composite was characterized by scanning electron microscopy (SEM), UV-Vis and Fourier-transform infrared (FT-IR) techniques. The characterization results concluded that the binding mechanism of the Cu(tpa) and GO was related to both packing and hydrogen bonding. For scrutinizing the sorption activity, the prepared adsorbents were assessed... 

Conformational diseases have been investigated extensively in recent years; as a result, a number of drug candidates have been introduced as amyloid inhibitors; however, no effective therapies have been put forward. RS-0406 with pyridazine as its core chemical structure has so far shown promising results in inhibiting amyloid formation. In the present work, using molecular dynamics, we undertook the investigation of RS-0406 interactions with U-shaped Aβ1−42 and Aβ1−40 pentamers, Aβ1−42 monomers, and double-horseshoe-like Aβ1−42. To set better parameters for the small molecule, experimental and computational log P values were obtained. In addition, an analogue of RS-0406 was also simulated... 

Palladium nanoparticles immobilized on the magnetic nanoparticles@2-amino-N-(2-aminoethyl) benzamide (MNPs@A-N-AEB.Pd0) have been presented as an efficient, and reusable magnetically heterogeneous catalyst for the C-O coupling reaction, namely Ullmann condensation reactions in an aqueous medium. This heterogeneous catalyst shows superior reactivity for the C-O arylation of different aryl halide (chloride, bromide, and iodide) with phenol derivatives to afford the desired products in good to excellent yields within short reaction time. Moreover, the catalyst can be easily recovered and reused for seven runs without loss of catalytic activity. The catalyst was characterized by several... 

In this study, the performance of the electrical method in MDF wastes recycling was determined. For investigating the practical aspect of the electrical method, the hydrothermal method as a known recycling method was studied too. The recycling process by electrical method conducted for two different time durations (2 and 4 min) at a temperature of 100 °C and recycling using the hydrothermal method was done at a temperature of 105 °C for 150 min under 4 bar pressure with subsequent refining step. Recycled fibers were analyzed by determination of the chemical composition of fibers and fiber classification. After that, laboratory MDF boards with dimensions of 35 × 35 × 12 mm3 and density of... 

We provide a physically motivated definition for the binding energy (or bond dissociation) of a bipartite quantum system. We consider coherently applying an external field to cancel out the interaction between the subsystems, to break their bond and separate them as systems from which no work can be extracted coherently by any cyclic evolution. The minimum difference between the average energies of the initial and final states obtained this way is defined as the binding energy of the system. We show that the final optimal state is a passive state. We discuss how the required evolution can be realized through a sequence of control pulses. The utility of our definition is illustrated through... 

The effect of anharmonicity on the adsorption of CO molecules on the Ni(111) surface has been investigated. The DFT calculations are used to obtain the effective adsorption potential of the CO molecule on the Ni(111) surface. First, using an appropriate slab model, the geometry of adsorption system corresponding to hep, fcc, bridge, and on-top sites with p(2 × 2) arrangement and coverage of 0.25 ML is optimized by the DFT calculations using a plane wave basis set and ultrasoft pseudopotentials; this gives the hep site as the most stable site with De = 185 kJ/mol, for which the equilibrium distance of CO from the surface and C-O bond length on the surface are found to be 1.31 and 1.192 Å,... 

Symmetric lattice relaxation around a vacancy in diamond and its effect on many electron states of the defect have been investigated. A molecular approach is used to evaluate accurately electron-electron (e-e) interaction via a semiempirical formalism which is based on a generalized Hubbard Hamiltonian. Coupling of the defect molecule to surrounding bulk is also considered using an improved Stillinger-Weber potential for diamond. Strong dependence of the electronic energy levels to the relaxation size of the nearest neighbor (NN) atoms indicates that in order to obtain quantitative results the effect of lattice relaxation should be considered. Except for the high spin state of the defect 5A... 

One of the most important biological components is lipid nanobio membrane. The lipid membranes of alive cells and their mechanical properties play an important role in biophysical investigations. Some proteins affect the shape and properties of the nanobio membrane while interacting with it. In this study a multiscale approach is experienced: first a 100ns all atom (fine-grained) molecular dynamics simulation is done to investigate the binding of CTX A3, a protein from snake venom, to a phosphatidylcholine lipid bilayer, second, a 5 micro seconds coarse-grained molecular dynamics simulation is carried out to compute the pressure tensor, lateral pressure, surface tension, and first moment of... 

Micro/nano gyroscopes which can measure angular rate or angle are types of merging gyroscope technology with MEMS/NEMS technology. They have extensively used in many fields of engineering, such as automotive, aerospace, robotics and consumer electronics. There are many studies of a variety of gyroscopes with various drive and detect methods and different resonator structures in last years. In case of electrostatically actuated and detected beam micro/nano-gyroscopes, DC voltages are applied in driving and sensing directions and AC voltage is utilized in driving direction in order to excite drive oscillation. The intermolecular surface forces are especially significant when the gyroscopes are... 

Abstract H2-rich water as a green antioxidant was applied for deoxygenation of graphene oxide (GO) suspensions. The ability of H2-rich water for deoxygenation of GO sheets was found comparable to the ability of hydrazine (as a standard and powerful reductant), using X-ray photoelectron spectroscopy. In fact, the O/C ratio of GO sheets could be reduced from 0.51 to 0.21 and 0.16 by H2-rich water and hydrazine, respectively. More importantly, while C-N bond formation is one of the side effects of GO reduction by hydrazine, no chemical C-N bond was found on the H2-water-reduced GO (rGO) sheets. This also resulted in a better restoration of the graphitic structure of the H2-water-rGO, as... 

In this study, influences of intermolecular forces on dynamic pull-in instability of electrostatically actuated beams are investigated. Effects of midplane stretching, electrostatic actuation, fringing fields and intermolecular forces are considered. The boundary conditions of the beams are clamped-free and clamped-clamped. A finite element model is developed to discretize the governing equations and Newmark time discretization is then employed to solve the discretized equations. The results indicate that by increasing the Casimir and van der Waals effects, the effect of inertia on pull-in values considerably increases  

Macroscale experiments show that a train of two immiscible liquid drops, a bislug, can spontaneously move in a capillary tube because of surface tension asymmetries. We use molecular dynamics simulation of Lennard-Jones fluids to demonstrate this phenomenon for NVT ensembles in submicron tubes. We deliberately tune the strength of intermolecular forces and control the velocity of bislug in different wetting and viscosity conditions. We compute the velocity profile of particles across the tube and explain the origin of deviations from the classical parabolae. We show that the self-generated molecular flow resembles the Poiseuille law when the ratio of the tube radius to its length is less... 

Theoretical study of NH3(H2O) n=0,1,2,3 adsorption on (8, 0) carbon nanotube was performed at the X3LYP/6-31G* level of density functional theory (DFT). The tube-NH3 interaction was discussed in the terms of binding energy (EB), coupling energy (EC), charge density, molecular orbitals, and dipole moments. The results reveal that addition of water molecules to tube-NH3 system increases the interaction between tube and ammonia molecule  

An approach to access azaborininones (carbonyl-containing, boron-based heterocyclic scaffolds) using simple reagents and conditions from both organotrifluoroborates and boronic acids is described. An inexpensive, common reagent, SiO2, was found to serve as both a fluorophile and desiccant to facilitate the annulation process across three different azaborininone platforms. Computational analysis of some of the cores synthesized in this study was undertaken to compare the azaborininones with the analogous carbon-based heterocyclic systems. Computationally derived pKa values, NICS aromaticity calculations, and electrostatic potential surfaces revealed a unique isoelectronic/isostructural...