Inhibition of corrosion of commercial mild steel in presence of tetrazole derivatives in acid medium

The inhibitive influence of tetrazole derivatives namely, 1-(9¹-acridinyl)-5-(4′-aminophenyl) tetrazole, 1-(9′-acridinyl)-5-(4′-hydroxy phenyl) tetrazole and 1-(9′-acridinyl)-5-(4′-chlorophenyl) tetrazole on the corrosion of commercial mild steel in 1 N hydrochloric acid medium was studied by weight loss method. The monolayer adsorption has been confirmed by fitting the data to the Langmuir adsorption isotherm. Weight loss studies have been carried out at 303K, 318K and 333K. Thermodynamic parameters like heat of adsorption, activation energy and free energy change have been calculated. The maximum inhibition of efficiency of tetrazole derivatives, 1-(9′-acridinyl)-5-(4′-amoinophenyl) tetrazole, 1-(9′acridinyl)-5-(4′-hydroxyphenyl) tetrazole and 1-(9′-acridinyl)-5-(4′-Chlorphenyl) tetrazole was found to be 60.59%, 89.00% and 92.74, respectively. Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.     

The role of propagating and evanescent waves in scanning near-field optical microscopy

Theoretical study on the image formation in scanning near-field optical microscopy is carried out in the framework of the direct moment method. Information brought, respectively, by the propagating and evanescent components in the optical near field that is collected by a scanning fiber tip with a sub-wavelength aperture is numerically and systematically analyzed in the light of the resolution achieved by the microscope. The analyses reveal that resolutions beyond the diffraction limit can be achieved even in the absence of the evanescent waves. That is, it is incorrect or at least incomplete to believe that a microscope that collects only the propagating waves is limited by the diffraction. Our studies show that a scanning near-field optical microscope can achieve resolutions beyond the diffraction limit by collecting only the propagating waves.     

Inhibition of corrosion of aluminium in presence of fluorescein in basic medium

The influence of Fluorescein in conjunction with calcium oxide on the corrosion of Aluminium in 1.0 N NaOH was studied by galvanostatic studies and weight loss studies. It has been found that the inhibition of corrosion of aluminium increased with the increasing concentration of the inhibitor. The maximum inhibition efficiency of fluorescein alone was found to be 30.80%. However, the addition of calcium oxide increased the maximum inhibition efficiency to 53.71%. The corrosion process was found to be under the anodic control, in the presence or in the absence of inhibitor. The inhibition was found to be mixed type. Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, Inida, Nov. 28–30, 2003.     

Exploring new mass regions with the ISOLTRAP spectrometer

First direct mass measurements on rare earth isotopes around ¹⁴⁶Gd have been performed with the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. More than 40 isotopes of the elements Pr, Nd, Pm, Sm, Eu, Dy and Ho have been measured with an accuracy of typically 1 × 10^-7. In the case of ¹⁴¹Sm isomeric and ground state (ΔE = 175 keV) were resolved. Since isobaric contaminations are present in the ISOLDE beam, these measurements on rare earth isotopes became only possible after the installation of a new cooler trap which acts an isobar separator. This revised version was published online in August 2006 with corrections to the Cover Date.     

Pertubations compactes des contractions multivoques

LetE be a Banach space, θ a multivalued contraction with closed values onE andf a continuous function fromE to itself with conditionally compact range. We prove that multifunction ψ=f+θ has fixed points if θ is convex-valued or if the range off is contained in a Lipschitz simple path. We also prove by counterexamples that the previous result is not true if the range off is only assumed to be homeomorphic to a segment or diffeomorphic to a circle.     

Direct potentiometric immunoelectrodes

Summary TK pencil fine mines type Faber Castell Super polymer from Staedtler are used as graphite based material for an atrazine-sensitive immunoelectrode. Eighteen procedures are tested to immobilize antibodies against atrazine but only one turned out to be useful for the preparation of a graphite based immunoelectrode. It incorporates binding of glutardialdehyde to active sites of the graphite surface and subsequent cross-linking of the antibodies with glutardialdehyde. The method has been carefully optimized with respect to selectivity and the cross-sensitivity is determined for such an electrode based on atrazine-rabbit and atrazine-sheep antibodies as well. Due to the structural difference of the used immunogens, the sign of the potential response and the cross-sensitivities are different. The application of such an electrode to a natural water sample is demonstrated and shows that the useful concentration range in a final solution is between 20 and 250 ng/l. Of course, interference from ions must be excluded in future analytical applications.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthdayPart II: Fresenius J Anal Chem     

Relative influence of two small parameters in non uniformly elliptic homogenization problems

We study three elliptic problems depending on two small parameters (? = homogenization parameter and δ = perturbation parameter which causes non uniform ellipticity). In each case, the homogenized operator corresponding to the second order operator is independent of the way (?, δ) → (0, 0), but the convergence results and the limit solution do depend on the relative size of ? and δ; the relevant parameter is δ?^?2.     

Direct potentiometric immunoelectrodes

A method is described to determine Atrazine and its cross-reacting relatives in water, using a previously described graphite based one-way immunoelectrode and any standard millivoltmeter with low input bias current. The new procedure separates the potential measuring step from the incubation step. In this way, the conditions for highly stable potential measurements and for a most effective formation of the hapten (Atrazine) antibody complex can be optimized separately and all imponderable influence from ions in the analyte water is excluded. The limit of detection of such an electrode is some nanogram per liter.Part III: see [4]