Unital Design Based Location Service for Subterranean Network Using Long Range Topology

Wireless Personal Communications - Wireless Underground Networks comprise the ability to constantly monitor several physical parameters such as ground temperature, water level and soil condition,...     

Dielectric behavior of gelatine–glycosaminoglycans blends: An impedance analysis

The dielectric behavior of the gelatine–GAGs based blend systems has been studied to understand the dynamic behavior of the water at the protein–GAGs interfaces which are relevant for tissue engineering application. Impedance (Z) and phase have been measured as a function of frequencies from 0.01 Hz to 100 kHz. GAGs tunes the ionic charge drift which initiates polarization mechanisms through charge accumulation at structural interfaces and creates conduction currents. The admittance results showed that at high frequency, the conductivity increases with increasing GAGs concentration indicating changes in hydration shell of the gelatine by the GAGs.     

Trivalent chromium removal from tannery effluent using kaolin‐supported bacterial biofilm of Bacillus sp isolated from chromium polluted soil

BACKGROUND: Bacterial strains belonging to the genus Bacillus, isolated from Cr‐ polluted soil (tannery sludge) were employed as consortium for Cr(III) removal from tannery effluents. Kaolin clay, a natural adsorbent, was used as supporting material for bacterial biofilm formation. The use of clay‐supported bacterial biofilm has not previously been employed for the treatment of tannery effluents containing Cr(III) salt. RESULTS: Commercial tannery effluent containing 1000 ppm initial metal ion concentration was treated in stages. The initial Cr(III) concentration of 1000 ppm was brought down to 2 ppm, a permissible level for discharge, after the fourth stage. The bacterial isolates were found to be Bacillus subtilis VITSCCr01 and Bacillus cereus VITSCCr02 by 16s rRNA gene sequencing. Batch assay and confocal laser scanning microscopy results revealed the role of kaolin as a support material in biofilm formation. Best fit was obtained with the Freundlich adsorption isotherm. The mechanism of sorption was confirmed by Fourier transform infrared (FT‐IR) spectroscopy and scanning electron microscopy–energy dispersive X‐ray spectroscopy (SEM‐EDS). CONCLUSION: Cr(III) removal from tannery effluent using low cost adsorbents such as kaolin and bacteria proved to be effective for metal concentrations ?1000 ppm; this is normally not possible using conventional treatment methods. This work has demonstrated feasible sorption of Cr(III), especially during post‐tanning operations. Copyright © 2011 Society of Chemical Industry     

Solid waste removes toxic liquid waste: adsorption of chromium(VI) by iron complexed protein waste

The leather processing industry generates huge amounts of wastes, both in solid and liquid form. Fleshing from animal hides/skins is one such waste that is high in protein content. In this study, raw fleshing has been complexed with iron and is used for removal of chromium(VI). The effect of pH and the initial concentration of chromium(VI) on the removal of Cr(IV) by iron treated fleshing is presented. Iron treatment is shown to greatly improve adsorption of the fleshing for hexavalent chromium. The ultimate adsorption capacity of iron treated fleshing is 51 mg of chromium(VI) per gram of fleshing. That of untreated fleshing is 9 mg/g such that iron treatment increases the adsorption capacity of fleshing by 10-fold. The measured adsorption kinetics is well described by a pseudo-second-order kinetic model. The uptake of chromium(VI) by fleshing is best described by the Langmuir adsorption isotherm model. X-ray photoelectron spectroscopic (XPS) studies show that the iron is incorporated into the protein matrix. Shifts in XPS spectra suggest that dichromate binding occurs with iron at active adsorption sites and that iron treated fleshing removes chromium(VI) without reducing it to chromium(III).     

Hydrodynamic lubrication of rough slider bearings with couple stress fluids

The combined effects of couple stresses and surface roughness on the performance characteristics of hydrodynamic lubrication of slider bearings with various film shapes, such as plane slider, exponential, secant and hyperbolic, are studied. A stochastic random variable with non-zero mean, variance and skewness is used to mathematically model the surface roughness of the slider bearing’s. The Stokes couple stress fluid model is used to characterize the rheological behavior of the lubricant with polymer additives. The modified expressions for the bearing characteristics, namely pressure, load carrying capacity, center of pressure, frictional force are obtained for the general lubrication film shape on the basis of Stokes microcontinuum theory for couple stress fluids. Results are computed numerically for various film shapes under consideration. It is observed that, for all the lubricant film shapes under consideration, the negatively skewed surface roughness increases the load carrying capacity, frictional force and temperature rise, while it reduces the coefficient of friction. On the contrary, the reverse trend is observed for positively skewed surface roughness. Further, these effects are more pronounced for the couple stress fluids.     

Nanohydroxyapatite-coated hydroxyethyl cellulose/poly (vinyl) alcohol electrospun scaffolds and their cellular response

The present study focused on the preparation of nanohydroxyapatite (nHA)-coated hydroxyethyl cellulose/polyvinyl alcohol (HEC/PVA) nanofibrous scaffolds for bone tissue engineering application. The electrospun HEC/PVA scaffolds were mineralized via alternate soaking process. FESEM revealed that the nHA was formed uniformly over the nanofibers. The nHA mineralization enhanced the tensile strength and reduced the elongation at breakage of scaffolds. The wettability of the nanofibrous scaffolds was significantly improved. The in vitro biocompatibility of scaffolds was evaluated with human osteosarcoma cells. nHA-coated scaffolds had a favorable effect on the proliferation and differentiation of osteosarcoma cell and could be a potential candidate for bone regeneration.     

Influence of PCL on the material properties of collagen based biocomposites and in vitro evaluation of drug release

Formulation of biodegradable collagen–poly-?-caprolactone (PCL) based biomaterials for the sustained release of insulin is the main objective of the present work. PCL has been employed to modulate the physico-chemical behavior of collagen to control the drug release. Designed formulations were employed to statistically optimize insulin release parameter profile at different collagen to PCL molar ratios. Circular dichroism, thermoporometry, FTIR, impedance and scanning electron microscopy techniques have been employed to investigate the effect of PCL on hydration dynamics of the collagen molecule, which in turn changes the dissolution parameters of the drug from the systems. Drug entrapment efficiency has been found to be maximum for collagen to PCL molar ratio of 1:2 (> 90%). In vitro dissolution test reveals that 99% of the drug was released from composite at collagen to PCL molar ratio of 1:3 and 1:4 within 2 h, which indicates that hydrophobicity of the matrix results in weak interaction between lipophilic drug and carrier materials. The least burst release was observed for collagen to PCL molar ratio at 1:2 as synergistic interactions between collagen and PCL was maximum at that particular polymer–polymer ratios. The drug release data indicates super case-II transport of drug (n > 1.0).     

Surface immobilisation of the sandwich type Na14[Fe4(Ox)4(H2O)2(SbW9O33)2]·60H2O polyoxometalate

A functionalised Fe-substituted Keggin Na₁₄[Fe₄(C₂O₄)₄(H₂O)₂(SbW₉O₃₃)₂]·60H₂O type POM termed “Fe₄Ox₄” has been successfully immobilised onto carbon electrode surfaces through the employment of conducting polypyrrole films and the layer-by-layer (LBL) technique. For the POM doped polypyrrole films the redox systems associated with the POM's tungsten-oxo framework was not apparent upon redox cycling, however a reversible redox couple associated with the Fe^III/II redox system was clearly seen within the pH range 2–7. Organised multilayer assemblies were constructed by the employment of the layer by layer (LBL) technique through alternating anionic Fe₄Ox₄ layers and cationic Ru^II metallodendrimers with poly(diallyldimethylammonium chloride) (PDDA) employed as an initial base layer. Stable redox couples associated with both the Fe^III/II and tungsten-oxo framework, for the Fe₄Ox₄ POM, and the Ru^III/II for the metallodendrimer, were clearly observed upon layer construction and redox switching within the pH domain of 2–7. The resulting multilayer assembly showed good stability towards redox cycling. Further investigations into the multilayer assembly were undertaken by determining it is charge transfer resistance using AC-impedance voltammetry. The layer also showed catalytic ability towards the reduction of H₂O₂ at pH 6.5.     

A facile spin-cast route for cation exchange of multilayer perpendicularly-aligned nanorod assemblies

A facile spin cast route was developed to convert perpendicularly aligned nanorod assemblies of cadmium chalcogenides into their silver and copper analogues. The assemblies are rapidly cation exchanged without affecting either the individual rod dimensions or collective superlattice order extending over several multilayers.     

A novel water‐soluble,conducting polymer composite for mild steel acid corrosion inhibition

A novel water‐soluble conducting polymer composite, poly(vinyl alcohol‐histidine) was synthesized from aqueous solution by free radical condensation using persulfate. The composite was characterized using UV–Visible, Fourier transform infrared, scanning electron microscopy, thermogravimetric analysis (TG/DTG), and differential scanning calorimetry techniques while its AC conductance was measured by LCZ analyzer. The inhibitive action of the composite on the corrosion behavior of mild steel in 1M HCl was studied by conventional weight loss method, potentiodynamic polarization studies (Tafel), linear polarization studies, and electrochemical impedance spectroscopy. The effects of inhibitor concentrations, exposure time, and temperature have been investigated. The corrosion rate, inhibition efficiency (IE), and other parameters have been evaluated for different inhibitor concentrations. The composite provided more than 95% IE at an optimum concentration of 0.6% by weight. The results showed the composite as an effective mixed type inhibitor. The adsorption of this inhibitor obeyed Temkin adsorption isotherm. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013