A modification on ECAP process by incorporating torsional deformation

In the present study, integration of equal channel angular pressing (ECAP), as a well known severe plastic deformation (SPD) technique, and torsion deformation, is studied by using three dimensional finite element analysis. This process is to be named as torsional-equal channel angular pressing (T-ECAP). In this modification a part of the exit channel in the ECAP die is rotating around its axis, to impose extra shear strains to the samples. To study deformation behavior in the T-ECAP process, three-dimensional finite element analysis (FEA) was carried out by using the elasto-plastic finite element analysis ABAQUS/Explicit Simulation. To investigate the validity of the simulation results, experimental studies were furthermore performed on commercially pure aluminum (AA 1050). Vickers hardness test was used to determine the distribution of hardness on both normal and longitudinal sections of the deformed samples with respect to the exit channel of the die. The hardness test results showed more uniform distribution of hardness in both sections of the T-ECAP processed samples regarding the ones produced by ECAP process. The load requirement comparison for performing both processes showed lower value for the T-ECAP with respect to the ECAP process. The simulation results for the strain values showed higher magnitude and more uniform distribution for the T-ECAP with respect to the ECAP process.     

PVC membrane potentiometric sensor based on 5-pyridino-2,8-dithia[9](2,9)-1,10-phenanthroline-phane for selective determination of neodymium(III)

Spectrofluorometric studies on the binding properties of 5-pyridino-2,8-dithia[9](2,9)-1,10-phenanthrolinephane (L) toward La3+, Sm3+, Gd3+, Yb3+, and Nd3+ in methanol solution revealed the occurrence of both 1:1 and 2:1 (ligand/metal) complexation with a stability order of Nd3+ > Yb3+ > Gd3+ > Sm3+ > La3+. Consequently, L was used as a suitable neutral ionophore for the preparation of a novel polymeric membrane-selective electrode for Nd3+ ion. The electrode exhibited a Nernstian response over a wide concentration range (1.0 x 10(-6)-1.0 x 10(-2) M) with a low limit of detection of 7.9 x 10(-7) M. The electrode possesses a fast response time of <5 s and can be used for at least 9 weeks without observing any considerable deviation. The proposed electrode revealed a very good selectivity for Nd3+ over a wide variety of alkali, alkaline earth, transition, and heavy metal ions, including members of the lanthanide family other than Nd3+. The potentiometric response of the electrode is independent of the pH of test solution in the pH range 4.0-6.5. The proposed electrode was successfully applied to the recovery of Nd3+ ion from tap water samples and, also, as an indicator electrode, in potentiometric titration of neodymium(III) ions.     

Simple determination of performance of explosives without using any experimental data

A simple procedure is introduced by which detonation pressure of CaHbNcOd explosives can be predicted from a, b, c, d and calculated gas phase heat of formation of explosives at any loading density without using any assumed detonation products and experimental data. It is shown here that the loading density, simply calculated heat of formation by additivity rule and atomic composition can be integrated into an empirical formula for predicting the detonation pressure of proposed explosives. Calculated detonation pressures by the introduced method for both pure and explosive formulations show good agreement with respect to measured detonation pressure over a wide range of loading density. The deviations are within about experimental errors.     

Urea combustion synthesis of nano-structure bimetallic perovskite FeMnO<Subscript>3</Subscript> and mixed monometallic iron manganese oxides: effects of preparation parameters on structural,opto-electronic and photocatalytic activity for photo-degradation of Basic Blue 12

Nano-structure bimetallic FeMnO₃ and mixed monometallic iron manganese oxides have been synthesized by a urea combustion method using iron (III) choloride, manganese (II) chloride tetrahydrate and urea and calcination at 400 and 650?°C. The structural, optoelectronic and morphological analysis of samples have been studied by XRD, FESEM, EDX, FTIR, and UV–vis DRS measurements. The effect of calcination temperature was examined and XRD results reveal that at 650?°C a pure nano-structure bimetallic FeMnO₃ with perovskite-type structure is formed while at calcination temperature of 400?°C mixed monometallic iron manganese oxides (Fe₂O₃ and Mn₂O₃) is produced. FT-IR spectrum of nano-structure bimetallic FeMnO₃ and mixed monometallic iron manganese oxides exhibited strong absorption band at 473, 523, 547 and 666 cm^?1 for Fe–O, Mn–O and Fe–O–Mn bond stretching vibrations. UV–vis DRS absorption spectrum exhibited absorption peaks at 211, 262, 384 and 520 nm located at UV and visible region of the solar light. FESEM results showed that the pure nano-structure bimetallic FeMnO₃ appears as nano-structure with an average diameter 29 nm. Elemental analysis results of EDX spectrum demonstrated the presence of iron, manganese and oxygen. The photo-catalytic properties of the nano-structure bimetallic FeMnO₃ and mixed monometallic iron manganese oxides coated on glass were evaluated via degradation of Basic Blue 12 (BB12) an oxazine class dyes under irradiation. The results showed the best photocatalytic performance, which achieved as high as 99% for BB12 degradation exposed 1.5 h irradiation which is due to UV and visible absorption, an efficient electron–hole separation and high surface area of nano size particle with an average size of 29 nm. The results showed that nano-structure bimetallic FeMnO₃ and mixed monometallic iron manganese oxides coated on glass is a promising photo-catalyst for the removal of Basic Blue 12 (BB12) an oxazine class dyes from wastewater.     

Sodium-dodecyl-sulphate-assisted synthesis of Ni nanoparticles: electrochemical properties

Stabilized nickel nanoparticles (SNNPs) were prepared using \(\hbox {Ni(acac)}_{2}\) (\(\hbox {acac} = \hbox {acetylacetonate}\)) via a simple solvothermal method. The synthesis of the nickel nanoparticles was performed in the presence of sodium dodecyl sulphate (SDS) of different concentrations (mole ratios of SDS:\(\hbox {Ni(acac)}_{2} = 1{:}1\), 2:1 and 4:1), as the stabilizer, in order to appraise their influence on the morphology, size, dispersion, magnetic properties and electrochemical activity of the nickel nanoparticles. The synthesized products have been characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry and electrochemical studies. It is noteworthy that the average particles size of the SNNPs has been reduced by increasing the SDS concentration, while at high concentration (mole ratio of SDS:\(\hbox {Ni(acac)}_{2} = 4{:}1\)), the small particles tend to coalesce and create a big one. The stabilized Ni nanoparticles could be used as electrode materials for hydrogen evolution in alkaline medium. The electrochemical measurements demonstrated that the higher conductivity and lower value of faraday resistance of the as-prepared samples were when the mole ratio of SDS:\(\hbox {Ni(acac)}_{2}\) was 2:1.     

Use of acrylic acid in the synthesis of molecularly imprinted polymers for the analysis of cyproheptadine

The synthesis and comparative characterization of molecularly imprinted polymers (MIP_s) with cyproheptadine (CYP), using two different monomers, acrylic acid (AA) and methacrylic acid (MAA), are described.Polyacids (PA) [poly(methacrylic acid) (PMAA) and poly(acrylic acid) (PAA)] were obtained by the radical polymerization of MAA and AA, respectively, in dichloromethane as the porogen solvent-imprinted medium. The non-covalent imprinting process was performed via thermal decomposition of an azo-initiator at 60 °C, using ethylene glycol dimethacrylate as the cross-linker and 2,2′-azobis(2-methylpropionitrile) as the initiator. The selectivities of MIP_s and NIP_s particles were evaluated in binding experiments of the four synthesized polymeric materials (MIP_aa, MIP_maa, NIP_maa and NIP_aa) with CYP. The effects of monomers on: a) the surface morphology, b) the binding capacity and c) the swelling properties of imprinted and non-imprinted polymers were studied and are presented here. Polymer material morphology was assessed with scanning electron microscopy (SEM). This revealed differences in monomer function, depending on which one was employed, as well as differences in function when polymerization occurred in the presence of template or without it. Non-specific retention of the template to NIP_s was higher for NIP_s-PAA polymers than for NIP_s-PMAA materials. In terms of specific binding (ΔQ = Q_MIP ? Q_NIP), MIP_maa showed the greatest value (53.47%) in comparison with MIP_aa (50.07%).     

Evaluation of hydrogen effect on the fatigue crack growth behavior of medium-Mn steels via in-situ hydrogen plasma charging in an environmental scanning electron microscope

Fatigue crack growth(FCG)tests were conducted on a medium-Mn steel annealed at two intercritical annealing temperatures,resulting in different austenite(γ)to ferrite(α)phase fractions and different γ(meta-)stabilities.Novel in-situ hydrogen plasma charging was combined with in-situ cyclic loading in an environmental scanning electron microscope(ESEM).The in-situ hydrogen plasma charging increased the fatigue crack growth rate(FCGR)by up to two times in comparison with the reference tests in vacuum.Fractographic investigations showed a brittle-like crack growth or boundary cracking manner in the hydrogen environment while a ductile transgranular manner in vacuum.For both materials,the plastic deformation zone showed a reduced size along the hydrogen-influenced fracture path in comparison with that in vacuum.The difference in the hydrogen-assisted FCG of the medium-Mn steel with different microstructures was explained in terms of phase fraction,phase stability,yielding strength and hydrogen distribution.This refined study can help to understand the FCG mechanism without or with hydrogen under in-situ hydrogen charging conditions and can provide some insights from the applications point of view.