Benevolent behavior ofKleinia grandifloraleaf extract as a green corrosion inhibitor for mild steel in sulfuric acid solution

The ethanolic extract of Kleinia grandiflora leaves was characterized and tested for its potential anticorrosion properties on mild steel in 1 M H2SO4 medium using mass-loss analysis, potentiodynamic polarization measurements, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, UV–visible spectroscopy, and X-ray diffraction analysis. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 308 to 328 K. The inhibition efficiency was observed to increase with increasing concentration of the extract. Polarization curves revealed that the Kleinia grandiflora leaf extract is a mixed inhibitor. Impedance diagrams revealed that an increase of Kleinia grandiflora leaf extract concentration increased the charge transfer resistance and decreased the double-layer capacitance. The adsorption process obeys Langmuir＇s model, with a standard free energy of adsorption（ΔGads） of-18.62 k J/mol. The obtained results indicate that the Kleinia grandiflora leaf extract can serve as an effective inhibitor for the corrosion of mild steel in a sulfuric acid medium.     

Corrosion Inhibition and Adsorption Behavior of Setaria verticillata Leaf Extract in 1M Sulphuric Acid

Setaria verticillata leaf extract (SVLE) as corrosion inhibitor in 1M H₂SO₄ was investigated by weight loss techniques and electrochemical techniques at 308-328 K. Inhibition efficiency of SVLE was found to increase with increasing concentration but decreased with temperature. Polarization measurements revealed that SVLE acted as mixed-type inhibitor. Impedance diagrams showed that increasing of SVLE concentration increased charge transfer resistance and decreased double layer capacitance. The adsorption of SVLE on the mild surface obeyed the Langmuir adsorption isotherm. Protective film formation against corrosion was confirmed by SEM and FTIR.     

Ionic Liquids Assisted Synthesis of ZnO Nanostructures:Controlled Size,Morphology and Antibacterial Properties

Systematic analysis about the exploitation of imidazolium based ionic liquids（ILs）,[BMIM]BF₄[IL1],[EMIM]BF₄ [IL2]and[BMIM]PF₆[IL3]as the morphological template on the basic sol-gel method adopted synthesis of nanostructured zinc oxide（ZnO） is presented.X-ray diffraction（XRD）,particle size analysis（PSA） and scanning electron microscopy（SEM） have been employed for the characterization of structure and morphology of the synthesized ZnO particles.Well-defined capsule like shaped morphology with lower nanosize is observed for the ZnO nanoparticles with IL1 than those with IL2 and IL3.This confirms that IL1 served as an effective templating material due to their unique properties.Especially the effective aggregation of ZnO particles with a self-organized frame of IL1 was the essential factor to produce the lower nanosized ZnO with capsule shaped structure.The synthesized ZnO samples with IL2 and IL3 fabricated the flake like shaped and rod like shaped morphologies in the range of nanoscale.The formed ZnO nanoparticles with IL2 exhibit higher nanosize than the ZnO nanoparticles produced by IL1,owing to shorter length of alkyl group in its cation which restricts steric effect and permits the nanoparticles to grow longer.Even though IL3 produced the discrete ZnO nanorods,the hydrophobic nature of IL3 created the higher nanosize than the ZnO nanoparticles formed by other two ionic liquids.Antibacterial properties of the synthesized ZnO nanostructures were investigated against Staphylococcus aureus（gram positive） and Escherichia coli（gram negative） bacteria by Agar diffusion test method.Microbial experiments indicate that the synthesized ZnO samples show a wide spectrum of antimicrobial activities and performed better against S.aureus than E.coli with the same concentration of ZnO.     

Analysis of C-F bond cleavages in methylfluorobenzoates—Fragmentation and dimerization of anion radicals using convolution potential sweep voltammetry

The electrochemical reduction of methylfluorobenzoates at glassy carbon electrodes is analyzed using the convolution potential sweep voltammetry (CPSV). The stabilization of the radical anion due to the electron-withdrawing group is shown to lead to intra-molecular stepwise dissociative electron transfer. While methyl 2-fluorobenzoate (ortho isomer) follows EC mechanism, the methyl 4-fluorobenzoate (para-isomer) undergoes electro-dimerization prior to C-F bond cleavage. The first order rate constant for the EC mechanism and the dimerization rate constant for the electro-dimerization are deduced from the classical as well as convolution potential sweep voltammetry. A plausible mechanism of dimerization is suggested. The influence of the electron-withdrawing groups is illustrated by comparing the reduction behaviour of 4-fluorobenzonitrile. The potential energy surfaces and electron density mapping employing Gaussian 03 calculations provide further support for the validation of the mechanism pertaining to C-F bond cleavages.     

Orientation effect on sign and magnitude of excess thermodynamic functions of non electrolyte solutions at different temperatures (303.15 K, 308.15 K,and 313.15K)

Experimental values of the density and viscosity have been measured for binary mixtures of N-ethylaniline with isomeric butanols (1-butanol, 2-butanol, 2-methyl-1-propanol and 2-methyl-2-propanol) at 303.15, 308.15 and 313.15 K over the entire mole fraction range. These data, the excess molar volumes, and deviation viscosity for the binary systems at the above-mentioned temperatures were calculated and fitted to Redlich-Kister equation to determine the fitting parameters and the root-mean-square deviations. The excess molar volumes, deviation viscosity and excess Gibbs energy of activation of viscous flow have been analyzed in terms of acid-base interactions, hydrogen bond, and dipole-dipole interaction between unlike molecules. The results obtained for dynamic viscosity of binary mixtures were used to test the semi-empirical relations of Grunberg-Nissan, Katti-Chaudhri, and Hind et al. equations.     

Structural,Optical,Antibacterial and Antifungal Properties of Zirconia Nanoparticles by Biobased Protocol

Biological entities and inorganic materials have been in constant touch with each other ever since inception of life on earth.This method has lots of merits such as not requiring complex procedures,template supporting etc.In this work,Aloe vera plant mediated synthesis of tetragonal zirconia nanoparticles has been performed and thermogravimetric and differential thermal analysis（TG/DTA）,X-ray diffraction（XRD）,scanning electron microscopy（SEM） with energy dispersive X-ray spectroscopy（EDX）,atomic force microscopy（AFM）,ultraviolet—visible（UV—VIS） technique and Fourier transform infrared spectroscopy（FTIR） have been provided for characterizing the nanoparticles.Formation of homogeneously distributed spherical zirconia nanoparticles of 50—100 nm in size is predicted.The antimicrobial and antifungal properties are also investigated for synthesis of zirconia nanoparticles and the treated cotton by agar diffusion method against Staphylococcus aureus and Escherichia coli bacterial pathogens and fungal strains Candida albicans and Aspergillus niger,respectively.     

Domain-driven data synopses for dynamic quantiles

In this paper, we present new algorithms for dynamically computing quantiles of a relation subject to insert as well as delete operations. At the core of our algorithms lies a small-space multiresolution representation of the underlying data distribution based on random subset sums or RSSs. These RSSs are updated with every insert and delete operation. When quantiles are demanded, we use these RSSs to estimate quickly, without having to access the data, all the quantiles, each guaranteed to be accurate to within user-specified precision. While quantiles have found many uses in databases, in this paper, our focus is primarily on network management applications that monitor the distribution of active sessions in the network. Our examples are drawn both from the telephony and the IP network, where the goal is to monitor the distribution of the length of active calls and IP flows, respectively, over time. For such applications, we propose a new type of histogram that uses RSSs for summarizing the dynamic parts of the distributions while other parts with small volume of sessions are approximated using simple counters.     

Local rules for protein folding on a triangular lattice and generalized hydrophobicity in the HP model

We consider the problem of determining the three-dimensional folding of a protein given its one-dimensional amino acid sequence. We use the HP model for protein folding proposed by Dill (1985), which models protein as a chain of amino acid residues that are either hydrophobic or polar, and hydrophobic interactions are the dominant initial driving force for the protein folding. Hart and Istrail (1996a) gave approximation algorithms for folding proteins on the cubic lattice under the HP model. In this paper, we examine the choice of a lattice by considering its algorithmic and geometric implications and argue that the triangular lattice is a more reasonable choice. We present a set of folding rules for a triangular lattice and analyze the approximation ratio they achieve. In addition, we introduce a generalization of the HP model to account for residues having different levels of hydrophobicity. After describing the biological foundation for this generalization, we show that in the new model we are able to achieve similar constant factor approximation guarantees on the triangular lattice as were achieved in the standard HP model. While the structures derived from our folding rules are probably still far from biological reality, we hope that having a set of folding rules with different properties will yield more interesting folds when combined.     

The effect of the PVC/CPVC ratio on the corrosion resistance properties of organic coatings

The effect of the ratio of the pigment volume concentration (PVC) to the critical pigment volume concentration (CPVC), denoted hereafter by Λ, on the corrosion resistance properties of paint films has been investigated by a.c. impedance and potential-time measurements. Painted mild steel electrodes were studied during exposure to 3% NaCl solution for up to 90 days. Paints based on alkyd, epoxy and chlorinated rubber/chlorinated paraffin (CR/CP) were prepared containing zinc phosphate as inhibitive pigment. The paints were prepared at Λ values 0.48, 0.51, 0.55, 0.58, 0.61, 0.64 and 0.67. It is concluded that, for all systems, corrosion resistance can be affected greatly by the PVC/CPVC ratio and each system has its own optimum Λ value. The optimum percentage of inhibitive pigment in the above systems has also been evaluated.