Sonoelectrochemical synthesis of a nanoscale complex of lead(II) and 2-methyl-8-hydroxyquinoline: spectroscopic, photoluminescence, thermal analysis studies and its application in an OLED

A new lead complex, [Pb(mq)₂], (mq = 2-methyl-8-hydroxyquinoline) was prepared via an electrochemical route from the oxidation of lead metal in the presence of 2-methyl-8-hydroxyquinoline in a fast and facile process. The complex was fully characterized by means of NMR and IR spectra and elemental analysis. The nanostructure of the prepared compound was obtained by sonoelectrochemical process and studied by scanning electron microscopy, atomic force microscopy, X-ray powder diffraction, IR spectroscopy and elemental analysis. Thermal stability of single crystalline and nanosize samples of the prepared compound was studied by thermal gravimetric and differential thermal analysis. The photoluminescence properties of the prepared compounds, as single crystals and as nanorods, have been investigated. The results showed a good correlation between the size and the shape of the complex particles and emission wavelength. The prepared complex was doped in PVK:PBD blend as guest and its application in the fabrication of OLED was studied. The ratio of lead complex was modified and was equal to 8 (w/w %) in PVK:PBD (100:40).     

Structural and Mechanical Properties of Al/B4C Composites Fabricated by Wet Attrition Milling and Hot Extrusion

In this study,Al matrix composites reinforced by 7.5 and 15 vol.%B₄C particles and also monolithic Al（Al without the B₄C particles） were produced by wet attrition milling and subsequent hot forward extrusion processes.The microstructure of the composites,evaluated by scanning electron microscopy（SEM）,showed that the B₄C particles were properly distributed in the Al matrix.Mechanical properties of the AI/B₄C composites and monolithic Al were investigated by tensile,wear and hardness tests.The results revealed that with increasing content of B₄C particles,the tensile strength and microhardness of composites increased but the elongation decreased.In addition,the tensile strength and microhardness of composite samples were higher than those of monolithic Al.The density measurements revealed that the density of composites decreased with increasing content of the B₄C particles.     

Electrical and magnetic properties of lithium borate glass containing iron

Journal of Materials Science Letters -     

The specific enthalpy of fracture for beta Ti-15-3 alloy

Fatigue crack propagation (FCP) experiments were conducted on beta Ti-15-3 alloy under various loading conditions to examine the constancy of the specific enthalpy for fracture, advanced by the Crack Layer (CL) theory as a material parameter characteristic of its intrinsic toughness. The energy release rate and the irreversible work were determined from load-displacement curves during crack propagation. Microscopic and diffraction analyses were conducted to identify the damage mechanisms ahead of the crack tip. A damage zone whose geometry exhibited plane strain character at the initial stage of crack propagation was observed optically. The damage zone transformed into plane stress configuration when the crack reached half its critical length. Damage mechanisms involved slip lines and microcracking which is believed to ensue from intense accumulation of slip processes. The magnitude of microcracking became more weighty as the crack moved deeper into plane stress dominance. The damage preceding crack advance was quantitatively assessed as the crack resistance moment which is the volume of transformed material per unit crack extension. Application of the CL theory to the data generated under a wide range of applied stress levels gave rise to a constant value of the specific enthalpy of fracture, 20 MJ/m³. This value is in close agreement with the specific energy of slip lines computed from microstructural considerations.     

Stability enhancement of polypyrrole thin film ammonia sensor by camphor sulfonic acid dopant

Journal of Materials Science: Materials in Electronics - The main weakness of polymer gas sensors is its stability. Here, we report stability enhancement of a 100 nm polypyrrole (PPy) thin...     

Comparison of stress field forming methods for vibro-acoustography

Vibro-acoustography is a method that produces images of the acoustic response of a material to a localized harmonic motion generated by ultrasound radiation force. The low-frequency, oscillatory radiation force (e.g., 10 kHz) is produced by amplitude modulating a single ultrasound beam, or by interfering two beams of slightly different frequencies. Proper beam forming for the stress field of the probing ultrasound is very important because it determines the resolution of the imaging system. Three beam-forming geometries are studied: amplitude modulation, confocal, and x-focal. The amplitude of radiation force on a unit point target is calculated from the ultrasound energy density averaged over a short period of time. The profiles of radiation stress amplitude on the focal plane and on the beam axis are derived. The theory is validated by experiments using a small sphere as a point target. A laser vibrometer is used to measure the velocity of the sphere, which is proportional to the radiation stress exerted on the target as the transducer is scanned over the focal plane or along the beam axis. The measured velocity profiles match the theory. The theory and experimental technique may be useful in future transducer design for vibro-acoustography.     

No-chatter model-free sliding mode control for synchronization of chaotic fractional-order systems with application in image encryption

Multimedia Tools and Applications - Synchronization of different Chaotic dynamical systems is one of the main issues in engineering which has a lot of applications in applied sciences like secure...     

A probabilistic model for assessing the reliability of wind farms in a power system

Modeling the generation of a wind farm and its effect on power system reliability is a challenging task, largely due to the random behavior of the output power. In this paper, we propose a new probabilistic model for assessing the reliability of wind farms in a power system at hierarchical level II (HLII), using a Monte Carlo simulation. The proposed model shows the effect of correlation between wind and load on reliability calculation. It can also be used for identifying the priority of various points of the network for installing new wind farms, to promote the reliability of the whole system. A simple grid at hierarchical level I (HLI) and a network in the north-eastern region of Iran are studied. Simulation results showed that the correlation between wind and load significantly affects the reliability.     

Investigating the effect of varying block size on power and energy consumption of GPU kernels

The Journal of Supercomputing - Power consumption is likely to remain a significant concern for exascale performance in the foreseeable future. In addition, graphics processing units (GPUs) have...     

A hybrid algorithm for scheduling scientific workflows in IaaS cloud with deadline constraint

The Journal of Supercomputing - Scientific workflows are used to process large amounts of data and perform complex analyses; thus, they require powerful computing resources to produce the desired...