Measurement of the amount and rate of methane dissolution in pure water and aqueous solution of SDS + multi-wall carbon nanotubes + β-cyclodextrin

In this paper, the impact of the mixture of sodium dodecyl sulfate (SDS) + multi-wall carbon nanotubes (MWCNTs) + β-cyclodextrin on the quantity and initial rate of methane dissolved in water is investigated. The experiments were performed at a temperature range of 278.15–303.15 K and an initial pressure of 0.5 MPa. The experimental results show that simultaneous utilization of β-cyclodextrin (0.01 mass fraction), MWCNTs (0.0005 mass fraction), and SDS (0.001 mass fraction) at 278.15 K increases the amount and the rate of methane dissolution in water by 29.90% and 173.78%, respectively, compared to pure water. An increase in the temperature decreases the quantity and the initial rate of methane dissolution in all solutions containing additives. However, no consistent relationship is observed between the temperature and the enhancement percentage of solubility of methane in solutions containing additives.     

An improved meshless method for analyzing the time dependent problems in solid mechanics

In this paper, the local radial point interpolation method (LRPIM) is developed for the investigation of time dependent problems in solid mechanics. By a new integration scheme considered for the obtained meshless weak form, integrands are approximated up to the second order of the Taylor series and the integrals are evaluated on some points, which are located inside the local quadrature domains, called integration points. In order to show the efficiency of the suggested method, some time dependent mechanical problems are considered for the engineering structures such as beams and plates, which are subjected to dynamical loads, the deflections and stresses are evaluated. Finally, it has been shown that using the proposed method greatly reduces the number of integration points without affecting the accuracy of the results.     

Fracture investigation of U‐notch made of tungsten–copper functionally graded materials by means of strain energy density

The averaged strain energy density over a well‐defined control volume was employed to assess the fracture of U‐notched specimens made of tungsten–copper functionally graded materials under prevalent mode II loading. The boundary of control volume was evaluated by using a numerical method. Power law function was employed to describe the mechanical properties (elasticity modulus, Poisson's ratio, fracture toughness and ultimate tensile stress) through the specimen width. The effect of notch tip radius and notch depth on notch stress intensity factors and mode mixity parameter χ were assessed. In addition, a comparison based on fracture load between functionally graded and homogeneous W–Cu was made. Furthermore, in this research, it was shown that the mean value of the strain energy density over the control volume can be accurately determined using coarse meshes for functionally graded materials.     

A priori error estimates for a linearized fracture control problem

Optimization and Engineering - A control problem for a linearized time-discrete regularized fracture propagation process is considered. The discretization of the problem is done using a conforming...     

Improvement in the Environmental Resistance to Oxidation and Surface Properties of Simple Carbon Steel Using Aluminum Coating

In the present work, using a new approach, Fe?CAl intermetallics were formed on the surface of a low-carbon steel (ST52) in order to study its effects on the oxidation, hardness and abrasive behavior. The samples were welded with gas tungsten arc welding technique using an aluminum?Ciron powder (stoichiometry ratio of 1:1) as filer. The microstructural evolutions of coated samples were then characterized using scanning electron microscopy and X-ray diffraction techniques. Besides, hardness and abrasion tests were carried out to study the abrasive behavior of coated layer. The resistance to hot oxidation of coated samples were evaluated by heating to 500, 600 and 700?°C and holding for 2?h. The results show that Fe₃Al and aluminum?Ciron carbide (FeAlC_0.65) were formed on surface of samples. The formation of these phases resulted in increase in the hardness and oxidation resistance, while no improvement on the wear resistance was observed.     

Aluminum Pitting Corrosion in Halide Media: A Quantum Model and Empirical Evidence

The phenomenon of localized damage of aluminum oxide surface in the presence of halide anions was scrutinized at an atomistic level, through the cluster approach and density functional theory. The phenomenon was also investigated empirically through Tafel polarization plots and scanning electron microscopy. A distinct behavior witnessed in the fluoride medium was justified through the hard-soft acid-base principle. The atomistic investigations revealed the greatest potency for chloride entrance into the metal oxide lattice and rationalized to the severity of damage. The interaction of halide anions with the oxide surface causing some displacements on the position of Al atoms provides a mechanistic insight of the phenomenon.     

Study the effect of distribution of density of states on the depletion width of organic Schottky contacts

Organic semiconductor to metal Schottky contacts have been widely used in electronic devices and to investigate the properties of organic semiconductors. In designing and characterizing these devices the full depletion approximation is used. The analytical and numerical simulations presented in this paper suggest that this approximation is not generally valid. Simulations of a Schottky contact between regioregular-poly 3 hexylthiophene (rr-P3HT) and aluminum show that this approximation becomes worse as molecular order decreases, with the potential profile increasingly deviating from the expected quadratic function of position. Also the depletion width decreasing well below that predicted using the approximation. In this work the slope of the band tail is used as a measure of disorder.     

Dipyridamole recognition and controlled release by uniformly sized molecularly imprinted nanospheres

We used novel synthetic conditions of precipitation polymerization to obtain uniformly sized molecularly imprinted nanospheres of dipyridamole for application in the design of new drug delivery systems. In addition, the morphology, drug release, and binding properties of molecularly imprinted polymers (MIPs) were studied, and the effects of morphology on other properties were investigated. The MIPs prepared by acetonitrile/chloroform (19:1, v/v) were uniformly sized nanospheres with an average mean diameter of approximately 88 nm at a wetted state, 50 nm at a dry state, and a polydispersity index of 0.062. The imprinted nanospheres showed excellent binding properties and had 62.7% of template binding compared with 17.1% of its blank polymer. The imprinted nanospheres with 67.5 (mg template/of polymer) of binding capacity had better imprinting efficiency than the 50.5% of binding capacity shown by irregularly shaped MIP particles that were prepared by chloroform. The molecular binding abilities of imprinted nanospheres in human serum were evaluated by HPLC analysis (binding about 77% of dipyridamole). Results from release experiments of MIPs showed a very slow, controlled, and satisfactory release of dipyridamole. The loaded drug was released up to 99% in 17 days for nanospheres and 22 days for irregularly shaped particles.