Effect of electrode rotation on the accuracy of hole reproduction in electrochemical drilling

Electrochemical drilling (ecd) with stationary electrodes produces an inaccurate and irregular hole shape profile. The effect of low speed workpiece (anode) rotation on the accuracy of hole reproduction and other related parameters in ecd has been studied. A theoretical analysis of the effect of workpiece rotation and electrolyte flow velocity is presented. It is concluded that a slow relative rotary motion between the electrodes helps to produce a better hole profile     

Influence of electron beam radiation on mechanical and thermal properties of styrene‐butadiene‐styrene block copolymer

Electron beam crosslinking of elastomers is a special type of crosslinking technique that has gained importance over conventional chemical crosslinking method, because the former process is fast, pollution free, and simple. The technique involves the impingement of high‐energy electrons generated from electron accelerators and the subsequent production of free radicals on target elastomers. These radicals result in crosslinking of elastomers via radical–radical coupling. In the process, some chain scission may also take place. In this work, a high‐vinyl (～ 50%) styrene‐butadiene‐styrene (S‐B‐S) block copolymer was used as the base polymer. An attempt was made to see the effect of electron beam radiation on the mechanical and thermal properties of the block copolymer. Radiation doses were varied from 25 to 300 kGy. Mechanical properties like tensile strength, elongation at break, modulus at different elongations, hardness, tear strength, crosslink density, and crosslink to chain scission of the irradiated samples were studied and compared with those of unirradiated ones. In this S‐B‐S block copolymer, a relatively low‐radiation dose was found effective in improving the level of mechanical properties. Differential scanning calorimeter and dynamic mechanical analyzer were used to study the thermal characteristics of the irradiated polymer. Influence of a stabilizer at different concentrations on the properties of S‐B‐S at varied radiation doses were also focused on. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Bilinear Coffin–Manson Relationship in Thin Sheets of Interstitial-Free Steel

Bilinear Coffin–Manson (C-M) as well as cyclic stress–strain (CSS) relationship is observed during low-cycle fatigue study (strain amplitude ?ε _t/2 = 0.0015 to 0.004) of an interstitial-free (IF) steel sheet unlike some of the earlier reports. In this work, an attempt has been made to correlate the observed bilinearity with the evolution of dislocation substructure and the nature of cyclic strain hardening in the selected steel. To achieve this goal, some of the low-cycle fatigue (LCF) tests were interrupted after the elapse of 2, 5, 10, 20, and 50 pct of fatigue life, and the microstructures at various stages were examined using TEM. Cyclic hardening at low-strain amplitudes (?ε _t/2 ≤ 0.0020) is predominantly due to dislocation–dislocation and dislocation–precipitation interaction. On the other hand, at high-strain amplitudes (?ε _t/2 > 0.0020), subgrains start forming much earlier in fatigue life, and there is an additional contribution of subgrains toward the total hardening. The above phenomenon leads to a difference in the values of cyclic strain-hardening exponents, e.g., 0.24 at low (?ε _t/2 ≤ 0.0020) and 0.45 at high ?ε _t/2, respectively. The above difference is reflected in the bilinear C-M plot around the transition ?ε _t/2 of 0.0020 as also observed in the CSS plot.     

Electrochemical synthesis of nanostructured polyaniline: Heat treatment and synergistic effect of simultaneous dual doping

Different nanostructured polyaniline (PAni) has been synthesized via facile template‐free electrochemical synthesis approach in aqueous medium. Instead of conventionally used aniline, aniline sulphate was used in electrochemical polymerization. The synthesis process involves simultaneous doping with combination of inorganic and organic acid, i.e., sulfuric acid (H₂SO₄) and p‐toluenesulfonic acid (PTSA) at different ratios keeping total dopant concentration constant. Synergistic increase in conductivity is observed and the best conductivity is achieved at 3:1 ratio of [H₂SO₄]:[PTSA]. Different nanostructures of PAni are revealed through morphological analysis consisting of nanosphere, nanorod, and clustered particles among which finer nanorods show the best electrical conductivity. Upon controlled heat treatment followed by further cooling, resistivity increases, but after one day it decreases again and in the optimized dual doped PAni, it approaches approximately the same value of initial resistance. Lattice strain and benzenoid to quinonoid ratio increases with heat treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Rapid removal of lead(II) ions from water using iron oxide–tea waste nanocomposite – a kinetic study

Lead (Pb) ions are a major concern to the environment and human health as they are contemplated cumulative poisons. In this study, facile synthesis of magnetic iron oxide–tea waste nanocomposite is reported for adsorptive removal of lead ions from aqueous solutions and easy magnetic separation of the adsorbent afterwards. The samples were characterised by scanning electron microscopy, Fourier transform‐infrared spectroscopy, X‐ray diffraction, and Braunner–Emmet–Teller nitrogen adsorption study. Adsorptive removal of Pb(II) ions from aqueous solution was followed by ultraviolet–visible (UV–Vis) spectrophotometry. About 95% Pb(II) ion removal is achieved with the magnetic tea waste within 10 min. A coefficient of regression R ²  ≃ 0.99 and adsorption density of 18.83 mg g⁻¹ was found when Pb(II) ions were removed from aqueous solution using magnetic tea waste. The removal of Pb(II) ions follows the pseudo‐second‐order rate kinetics. External mass transfer principally regulates the rate‐limiting phenomena of adsorption of Pb(II) ions on iron oxide–tea waste surface. The results strongly imply that magnetic tea waste has promising potential as an economic and excellent adsorbent for the removal of Pb(II) from water.Inspec keywords: visible spectra, scanning electron microscopy, mass transfer, ultraviolet spectra, X‐ray diffraction, nanocomposites, lead, adsorption, magnetic separation, iron compounds, nanofabrication, Fourier transform infrared spectraOther keywords: FeO, Pb, time 10.0 min, X‐ray diffraction, Fourier transform‐infrared spectroscopy, scanning electron microscopy, adsorbent, magnetic separation, rapid removal, Braunner–Emmet–Teller nitrogen adsorption, iron oxide–tea waste surface, magnetic tea waste, aqueous solution, adsorptive removal, magnetic iron oxide–tea waste nanocomposite, lead(II) ions     

New insights into the cholesterol esterase- and lipase-inhibiting potential of bioactive peptides from camel whey hydrolysates: Identification,characterization, and molecular interaction

Novel antihypercholesterolemic bioactive peptides (BAP) from peptic camel whey protein hydrolysates (CWPH) were generated at different time, temperature, and enzyme concentration (%). Hydrolysates showed higher pancreatic lipase- (PL; except 3 CWPH) and cholesterol esterase (CE)-inhibiting potential, as depicted by lower half-maximal inhibitory concentration values (IC₅₀ values) compared with nonhydrolyzed camel whey proteins (CWP). Peptide sequencing and in silico data depicted that most BAP from CWPH could bind active site of PL, whereas as only 3 peptides could bind the active site of CE. Based on higher number of reactive residues in the BAP and greater number of substrate binding sites, FCCLGPVPP was identified as a potential CE-inhibitory peptide, and PAGNFLPPVAAAPVM, MLPLMLPFTMGY, and LRFPL were identified as PL inhibitors. Molecular docking of selected peptides showed hydrophilic and hydrophobic interactions between peptides and target enzymes. Thus, peptides derived from CWPH warrant further investigation as potential candidates for adjunct therapy for hypercholesterolemia.     

Dynamic participation of doubly fed induction generator in automatic generation control

Increasing levels of wind generation have resulted in an urgent need for the assessment of their impact on frequency control of power systems. The displacement of conventional generation with wind generation will result in erosion of system frequency. The paper analyzed the dynamic participation of doubly fed induction generator (DFIG) to system frequency responses of two-area interconnected power system having variety of conventional generating units. Frequency control support function responding proportionally to frequency deviation is proposed to take out the kinetic energy of turbine blades in order to improve the frequency response of the system. Impacts of different wind penetrations in the system and varying active power support from wind farm on frequency control have been investigated. Integral gains of AGC loop are optimized through craziness-based particle swarm optimization (CRPSO) in order to have optimal transient responses of area frequencies, tie-line power deviation and DFIG parameters.     

Kinetics of extraction of Ti(IV) from SO42– medium by Cyanex 301 dissolved in kerosene containing 5% heptan-1-ol

The kinetics of Ti(IV) extraction by Cyanex 301 (HA) were investigated by measuring initial flux of Ti(IV) transfer (F, kmol/m²s), using a Lewis cell, operated at 3 Hz. The empirical flux equation at 298 K is found to be as follows: F (kmol/m²s) = 10^–4.288 [Ti(IV)] (1 + 447 [H⁺])^–1 [HA]_(o) (1 + 1.18[SO₄^2–])^–1. The activation energy, E_a, has been measured to be within 37–60 kJ/mol, depending on experimental parameters and temperature region. The ΔS^± value is always highly negative. Analysis of the flux equation has been done, given various parametric conditions, to elucidate the mechanism of extraction. The rate-determining chemical reaction step, in most parametric conditions, appears to be as follows: TiO²⁺ + A^– → TiOA⁺; and this step occurs via an S_N2 mechanism as suggested by high negative ΔS^± values. However, in certain cases, the extraction process appears as intermediate controlled as supported by E_a value of less than ~48 kJ/mol.