Intensification of the reaction between Udaipur rock phosphate and sulphuric acid by means of ultrasound

The solid-liquid reaction between Udaipur rock phosphate and different concentrations of sulphuric acid is found to be greatly enhanced when the reaction is carried out in the presence of high intensity ultrasound (800 kHz and 80 W cm^?2). Even coarser rock particles up to 50 mesh (BSS) can be effectively decomposed in the presence of ultrasound to such an extent that is suitable for utilization in a commercial phosphatic fertilizer plant, which is not otherwise possible. The ultrasound helps the diffusion of reactants on to the solid rock particles and also inhibits the coating of calcium sulphate, formed during the reaction, on the unreacted solid rock particles. The decomposition curve of Udaipur rock phosphate at 80°C with different concentrations of sulphuric acid contains two maxima and two minima which are controlled by the concentration of H₃O⁺, HSO₄^? and SO₄^2? ions in the medium as the reaction proceeds. It is found that the presence of ultrasound reduces the difference between these maxima and minima and the decomposition is increased in all cases.     

Influence of high intensity ultrasound on wet process phosphoric acid

High intensity ultrasound (800 kHz and 80 Wcm^-2) is passed through phosphoric acid of different origins and concentrations. Its influence on fluorine content, viscosity, density, colour and tendency to form sludge on ageing is observed. The quantity of fluorine in all samples of acid goes on decreasing with the time of exposure to ultrasound. Due to removal of fluorine by the ultrasound, the tendency of the acids to form sludge also decreases. The evolution of fluorine from the wet process phosphoric acid may be due to the decomposition of H₂SiF₆ present in the acid to HF and SiF₄ by the enormous amount of energy released due to cavitation. The exposed acid thus becomes purer, and can be concentrated and transported easily without sludge formation.     

Fabrication of a metal nanoparticles and polymer nanofibers composite material by an in situ chemical synthetic route

This work demonstrated a facile route for the synthesis of poly(3,5-dimethyl aniline) nanofibers by polymerization of 3,5-dimethyl aniline using Pd-acetate as the oxidant. The reduction of Pd ion is accompanied by oxidative polymerization of 3,5-dimethyl aniline, leading to a metal-polymer composite material. Palladium nanoparticles (approximately 2 nm) are uniformly distributed throughout the polymer that makes the composite material a unique morphology. The resultant composite material was characterized by means of different techniques. IR and Raman spectra provide the information on the chemical structure of the polymer. TEM images show the morphology of the polymer and size of the metal particles.     

Observation of a phase object using carrier-frequency photography

A Ronch ruling is photographed through a phase object which produces deformations in the grating lines. The superposition of the straight rulings and the deformed ones on the photographic plate gives rise to a moiré pattern which characterises the phase variations of the object.     

Monitoring Membrane Protein Conformational Heterogeneity by Fluorescence Lifetime Distribution Analysis Using the Maximum Entropy Method

Due to the inherent difficulty in crystallizing membrane proteins, approaches based on fluorescence spectroscopy have proved useful in elucidating their conformational characteristics. The ion channel peptide gramicidin serves as an excellent prototype for monitoring membrane protein conformation and dynamics due to a number of reasons. We have analyzed conformational heterogeneity in membrane-bound gramicidin using fluorescence lifetime distribution analysis of tryptophan residues by the maximum entropy method (MEM). MEM represents a model-free and robust approach for analyzing fluorescence lifetime distribution. In this paper, we show for the first time, that fluorescence lifetime distribution analysis using MEM could be a convenient approach to monitor conformational heterogeneity in membrane-bound gramicidin in particular and membrane proteins in general. Lifetime distribution analysis by MEM therefore provides a novel window to monitor conformational transitions in membrane proteins.     

Characterization of collagen fibers in Bruch’s membrane using chemical force microscopy

Bruch’s membrane is a layer composed of collagen fibers located just beneath the retina. This study validates a strategy used to map the morphological and adhesion characteristics of collagen fibers in Bruch’s membrane. Atomic force microscopy tips were functionalized with different chemical groups and used to map the hydrophilic and hydrophobic regions on the surface of the eye tissue. The largest adhesion forces were observed when tips functionalized with NH₂ groups were used. The trend in the adhesion forces was rationalized based on the distribution of different functional groups in the triple-helical structure of the collagen fibers. The results of this study can be used to design more effective strategies to treat eye diseases such as age-related macular degeneration.     

Integrability of the discretization of the controlled Euler Top

The Euler equations with two controls are discretized by using the bilinear transformation method. The discrete equations are explicit and exhibit a sufficient number of conserved quantities for integrability. The explicit solution to the discrete controlled Euler top are deduced in terms of elliptic functions.     

The impact of information technology on the banking industry

This paper analyses the effects of investment in information technologies (IT) in the banking sector using bank-level data from a panel of 68 US banks over the period 1986–2005. Although IT can improve bank's performance by reducing operational cost (supply side), it can bring in competition among banks in order to embrace new technology (demand side). Since most empirical studies have adopted the production function approach, it is difficult to identify which effect has dominated. In a differentiated model with network effects, this paper characterizes the conditions to identify these two effects. The results suggest that (at individual firm levels) the bank profits can decline due to adoption and diffusion of IT investment, reflecting negative network competition effects in this industry. Using panel cointegration tests, we confirm that the estimated profit equation is indeed a long-run equilibrium relation.     

A phenomenological model for bake hardening in minimal carbon steels

The essence of bake hardening is to exploit the classical strain ageing in a positive way to increase the strength of the formed steel sheets used in outer body panel of a passenger car during the paint-baking operation. A new model that takes into account the strengthening contributions from Cottrell atmosphere and precipitate formation has been developed in the present work. The model predicts the increase in strength as a function of the amount of free solute C (calculated as a function of the annealing temperature), the amount of deformation, ageing temperature and time. The model predictions have been found to agree quite well with the experimental results; the individual contributions of Cottrell atmosphere and precipitation strengthening have been quantified.     

Boat-like Au nanoparticles embedded mesoporous γ-Al2O3 films: an efficient SERS substrate

A new water-dispersible nanostructure based on magnetite (Fe₃O₄) and usnic acid (UA) was prepared in a well-shaped spherical form by a precipitation method. Nanoparticles were well individualized and homogeneous in size. The presence of Fe₃O₄@UA was confirmed by transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray diffraction. The UA was entrapped in the magnetic nanoparticles during preparation and the amount of entrapped UA was estimated by thermogravimetric analysis. Fabricated nanostructures were tested on planktonic cells growth (minimal inhibitory concentration assay) and biofilm development on Gram-positive Staphylococcus aureus (S. aureus), Enterococcus faecalis (E. faecalis) and Gram-negative Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) reference strains. Concerning the influence of Fe₃O₄@UA on the planktonic bacterial cells, the functionalized magnetic nanoparticles exhibited a significantly improved antimicrobial activity against E. faecalis and E. coli, as compared with the Fe₃O₄ control. The UA incorporated into the magnetic nanoparticles exhibited a very significant inhibitory effect on the biofilm formed by the S. aureus and E. faecalis, on a wide range of concentrations, while in case of the Gram-negative microbial strains, the UA-loaded nanoparticles inhibited the E. coli biofilm development, only at high concentrations, while for P. aeruginosa biofilms, no inhibitory effect was observed. The obtained results demonstrate that the new water-dispersible Fe₃O₄@UA nanosystem, combining the advantages of the intrinsic antimicrobial features of the UA with the higher surface to volume ratio provided by the magnetic nanocarrier dispersible in water, exhibits efficient antimicrobial activity against planktonic and adherent cells, especially on Gram-positive strains.