Analytical solution of amperometric enzymatic reactions based on Homotopy perturbation method

Electrochemical polymerization is a simple and direct technique often employed for immobilizing redox enzymes at an electrode surface. Besides these, it allows precise control over the amount, spatial distribution and orientation of the enzymes. Analytical expressions pertaining to the immobilization of enzyme by electrochemical polymerization on the electrode surface were obtained by Homotopy perturbation method (HPM). This expression further distinguishes the product of the enzyme reaction at the electrode surface from those occurring alongside the polymer employed for immobilization. These analytical results are compared with the available limiting case results and they are found to be in good agreement.     

Novel Li-ion conduction on poly(vinyl acetate)-based hybrid polymer electrolytes with double plasticizers

Polymer blend electrolytes comprising of poly(vinyl acetate), poly(vinylidene fluoride-co-hexafluoropropylene), LiClO₄, and EC-based plasticizer combinations (EC + PC, EC + GBL, EC + DMP, EC + DBP, EC + DEC) are prepared by solvent casting technique. Ionic conductivities of the electrolytes are determined by ac impedance studies in the temperature range 303–363 K. Among the various combinations of plasticizers, EC + PC added complex exhibits maximum ionic conductivity of the order of 10⁻⁴ S cm⁻¹ and the temperature-dependent ionic conductivity plots seem to obey the VTF relation. The structural and complex formations of the prepared samples have been confirmed by X-ray diffraction analysis. DSC technique is used to study the thermal behaviour. The surface images of the sample having maximum ionic conductivity are analyzed with the help of SEM and AFM techniques.     

Modularization of a Large-Scale Business Application: A Case Study

Large software systems, developed over several years, are the backbone of industries such as banking, retail, transportation, and telecommunications. With multiple bug fixes and feature enhancements, these systems gradually deviate from the intended architecture and deteriorate into unmanageable monoliths. This article presents a case study of a banking application besot with such problems and the modularization approach that the company adopted as a solution. It also highlights benefits unearthed as a result of this reengineering exercise.     

Effect of External Stress on the Behavior of Oxide Scales on 9Cr-1Mo Steel

Tensile specimens of 9Cr-1Mo steel weresubjected to oxidation in air at a temperature of 973 Kfor periods of 25, 47, 70, 97, 120, and 140 hr. Theintegrity of the oxide scale was examined by an in-situ technique which involved the recording of theacoustic-emission activity associated with the breakingof the scale. Specimens were also subjected to oxidationfor the same times after subjecting them to an external stress of 40 MPa. The applicationof the external stress was found to alter the integrityof the scale. Spalling of the scale occurred to a lesserextent when external stress was applied due to partial release of growth stresses becauseof the elongation of the specimen. The scale buckledbefore spalling when no external stress was applied. Onthe other hand, the scale developed wedge-type cracks before spalling when subjected toexternal stress during oxidation. Postoxidationexamination of the stressed specimen revealedsubstantial segregation of silicon and chromium at thegrain boundaries (oxide ridges). The specimens, which wereoxidized without external stress, revealed a reductionin the concentration of chromium on the surface. Thisbehavior was attributed to enhanced spalling in the case of the latter specimen compared to theformer.     

Corrosion inhibition of mild steel by benzotriazole derivatives in acidic medium

Benzotriazole derivatives, namely, N-[1-(benzotriazolo-1-yl)alkyl] aryl amine (BTMA), N-[1-(benzotriazolo-1-yl)aryl] aryl amine (BTBA), and 1-hydroxy methyl benzotriazole (HBTA), were synthesized and their inhibition behaviour on mild steel in 0.5 M H₂SO₄ at room temperature was investigated by various techniques. Preliminary screening of the inhibition efficiency (IE) was carried out using weight-loss measurements. Potentiodynamic polarization and AC impedance studies were used to investigate the inhibitor mechanism. Benzotriazole derivatives were found to act as mixed type inhibitors. Among the compounds studied, HBTA exhibited the best performance giving more than 95% IE in H₂SO₄ solutions. The passive film characterization was done using FTIR spectrum.     

Atomic Force and Ultrasonic Force Microscopic Investigation of Laser-Treated Ceramic Head Sliders

The surface of laser-treated ceramic hard disk drive head sliders has been imaged with the atomic force microscope (AFM) and ultrasonic force microscope (UFM). The surface topography image from the AFM is compared with the elasticity image generated by the UFM on the same region. Images of the surface structure changes along with microcracking in the laser-treated regions are presented. The possible reasons for the development of microcracking and the enhanced contrast that the UFM provides of the microcracks and the material microstructure changes in the laser-treated region are discussed.     

Deposition of poly(diphenylamine‐co‐o‐chloroaniline) by pulse potentiostatic method: Growth equation and characterization

Electrochemical copolymerization of diphenylamine (DPA) with o‐chloroaniline (OCA) was performed in aqueous 4M sulfuric acid using the pulse potentiostatic method (PPSM). By employing the tunable parameters in PPSM, polymeric films were deposited under different conditions. Cyclic voltammetry was used for evaluating the characteristics of the deposited polymeric films. A suitable growth equation for the deposition of polymer, relating the charge associated for the film deposition and the pulse parameters in PPSM, was deduced. Various surface parameters are evaluated. The formation of copolymer during PPSM deposition was revealed through critical analysis of the results. The characteristic differences between the individual homopolymers, poly(diphenylamine) and poly(o‐chloroaniline) and the copolymer, poly(diphenylamine‐co‐o‐chloroaniline), were brought out. The copolymer was also synthesized through a chemical method and characterized through infrared and ultraviolet‐visible spectroscopic analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 389–397, 2003     

How Perception Impacts on Drawings.

In 3 experiments the authors investigate how errors in perception produce errors in drawings. In Experiment 1, when Shepard stimuli were shown as a pair of tables, participants made severe errors in trying to adjust 1 part of the stimulus to match the other. When the table legs were removed, revealing a pair of parallelograms with minimal perspective cues, the illusion was weaker. The authors predicted that participants would err when drawing the table but not the parallelogram stimuli. The results of Experiment 2 support the prediction and establish a direct link between degree of perceptual distortion of the table stimuli and the severity of error in drawing. When drawing only the right-hand part of the figure, participants also erred to a greater degree in drawing the table than the parallelogram (Experiment 3). Collectively, the results suggest that perceptual distortion is linked with errors in drawing the table stimuli. (PsycINFO Database Record (c) 2011 APA, all rights reserved)