Securing and Self recovery of Virtual Machines in cloud with an Autonomic Approach using Snapshots

Mobile Networks and Applications - The advent of cloud computing has been so enormous that, cloud has been seen as the most enduring technology of today’s technology scenario. It is known to...     

In Vitro/In Vivo Toxicity Evaluation and Quantification of Iron Oxide Nanoparticles

Increasing biomedical applications of iron oxide nanoparticles (IONPs) in academic and commercial settings have alarmed the scientific community about the safety and assessment of toxicity profiles of IONPs. The great amount of diversity found in the cytotoxic measurements of IONPs points toward the necessity of careful characterization and quantification of IONPs. The present document discusses the major developments related to in vitro and in vivo toxicity assessment of IONPs and its relationship with the physicochemical parameters of IONPs. Major discussion is included on the current spectrophotometric and imaging based techniques used for quantifying, and studying the clearance and biodistribution of IONPs. Several invasive and non-invasive quantification techniques along with the pitfalls are discussed in detail. Finally, critical guidelines are provided to optimize the design of IONPs to minimize the toxicity.     

Enhanced photocatalytic and antibacterial activities of sol–gel synthesized ZnO and Ag-ZnO

Nanocrystalline ZnO and Ag-ZnO (0.1 at%) have been synthesized by sol–gel method and characterized by X-ray diffraction, energy dispersive X-ray spectrum, scanning electron micrographs and UV–vis diffuse reflectance, photoluminescence and electrochemical impedance spectra. Doping ZnO with Ag reduces the average crystal size, sharpens the band gap absorption and decreases the charge-transfer resistance. The bactericidal and photocatalytic activities of sol–gel synthesized ZnO, tested, respectively, with Escherichia coli and cyanide ion, are larger than those of commercial ZnO nanoparticles. Ag doping by sol–gel method enhances the antibacterial and photocatalytic activities; the latter has been tested using methylene blue, methyl orange and rhodamine B.     

Inhibition of Cast Iron Corrosion in Acid, Base, and Neutral Media Using Schiff Base Derivatives

Three Schiff bases, 2-acetylpyridine thiosemicarbazone (I ₁ ), 2-acetylpyridine-(4-methylthiosemicarbazone) (I ₂ ), and 2-acetylpyridine-(4-phenylthiosemicarbazone) (I ₃ ) were tested against corrosion of cast iron in aqueous solutions of HCl, NaOH, NH₄Cl, and NaCl by means of a mass loss method and electrochemical measurements. The inhibition efficiency is directly proportional to inhibitor concentration, while it decreases with prolonged immersion time and at low temperatures. In order to study the effect of an additive, synergism of KI was also studied. The adsorption of Schiff bases in corrosive media obeys Langmuir’s isotherm, both in the presence and absence of KI. The UV–Vis, FT-IR, WAXD and SEM analyses were carried out to support the mechanism of corrosion inhibition. The ΔG _ads values reveal that the inhibition was mainly due to physisorption of the inhibitor molecules on the surface of cast iron. The electrochemical polarization results showed the predominantly cathodic nature of the inhibitors.     

Surface protection of copper in acid medium by azoles and surfactants

The influence of derivatives of 1,2,4 triazole, 3-amino 1,2,4-traizole (ATA), 3-amino 5-mercapto 1,2,4 triazole (AMT) and 3-amino 5-methylthio 1,2,4 triazole (AMTT) and ionic surfactants cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) on the corrosion control of copper in acidic solution was investigated by gravimetric and electrochemical methods. The combined effect of triazoles and surfactants was also evaluated. Electrochemical parameters like corrosion potentials corrosion current density, corrosion rates and inhibition efficiencies were determined. The results reveal the fact that of all triazoles AMTT shows best inhibition and anionic surfactant SDS protects the surface better than the cationic surfactant CTAB. The polarisation data reveal that all inhibitors behave as a mixed type inhibitor. Adsorption of these inhibitors on the surface of copper is found to obey the Langmuir adsorption isotherm. A marked inhibition synergism effect is shown by all the combinations of triazole and surfactant.     

Development of calcium phosphate based apatite from hen’s eggshell

Stoichiometric hydroxyapatite with Ca/P molar ratio, 1.67, was synthesized using hen’s eggshell as calcium source and phosphoric acid by precipitation method. Conventional EDTA titration and gravimetric methods were adopted to estimate the amount of calcium and phosphorous, respectively. Fourier-transform infrared (FT-IR) and X-ray diffraction (XRD) techniques were employed to investigate the formation of the HAP phase. Thermal analysis (TG-DTA) was carried out to investigate the thermal stability of HAP powder. FT-IR spectra show the characteristic peaks for phosphate and hydroxyl groups. XRD results reveal that the major characteristic peaks of HAP appear in the region of approximately 26°, 28°, 29°, 30–35°, 39°, 46°, 49° and 50° (2θ) and also indicate that there are no occurrences of secondary phases during HAP formation. TG-DTA result depicts that the synthesized HAP was stable up to 1300°C.     

Influence of phosphoric acid on the grid alloys of positive plates in the lead acid battery system: A comparative study

The effect of phosphoric acid in lead acid batteries was studied with potential sweep techniques. Lead–tin (2%) and lead–calcium (0.1%) tin (0.35%) alloys were used as the grids. The influence of phosphoric acid in the presence of tin, calcium and calcium alone on the grid were examined. Phosphoric acid inhibits the formation of β-PbO₂ in the alloys.     

Surface and electrochemical characterization of pitting corrosion behaviour of 304 stainless steel in ground water media

The effectiveness of aminotrimethylidene phosphonic acid (ATMP) as a corrosion inhibitor in association with a bivalent cation like Zn²⁺ and non-ionic surfactant like polyoxyethylene sorbitan monooleate (Tween 80) were investigated by measuring corrosion losses using electrochemical techniques. The corrosion of 304 stainless steel in the ground water medium was inhibited by complexation of the inhibitor. A combined inhibition effect was achieved by adding both ATMP and Zn²⁺ along with Tween 80. The formulation functioned as a mixed type inhibitor. The synergistic effect of the inhibitor compound is calculated. Luminescence spectra, FTIR spectra, XRD, XPS and scanning electron microscopic studies were carried out to understand the mode of corrosion inhibition and also the morphological changes on the metal surface.     

An electron energy loss spectrometer designed for studies of electronic energy losses and spin waves in the large momentum regime

Based on 143° electrostatic deflectors we have realized a new spectrometer for electron energy loss spectroscopy which is particularly suitable for studies on surface spin waves and other low energy electronic energy losses. Contrary to previous designs high resolution is maintained even for diffuse inelastic scattering due to a specific management of the angular aberrations in combination with an angle aperture. The performance of the instrument is demonstrated with high resolution energy loss spectra of surface spin waves on a cobalt film deposited on the Cu(100) surface.