Removal of lead from contaminated water bodies using sea nodule as an adsorbent

Adsorption of water soluble lead on polymetallic sea nodule has been studied in detail. Complete decontamination of lead is possible by appropriate sea nodule dosing. Adsorption is also dependent on pH and best adsorption is achieved at pH 6. Beyond pH 6, the desorption of lead from sea nodule surface is practically zero. Residual metal concentrations in the filtrate after adsorption is negligible. Both Freundlich and Langmuir isotherms may reasonably explain adsorption of lead on sea nodule. Chemically bound moisture plays a very crucial role in lead adsorption. Lead adsorptive capability of sea nodule is practically destroyed when calcined at a temperature of 900 degrees C. Lead loading capacity of sea nodule has been estimated at 440 mg of lead per gram of sea nodule. The performance of sea nodule as a lead adsorbent has been successfully tested over six simulated lead contaminated water systems. Lead loading capacity of sea nodule compares favorably with other adsorbents like activated carbon, ion exchange resin, anionic clay, granulated blast furnace slag and natural and treated zeolites.     

Development and characterization of magnesium composites containing nano-sized silicon carbide and carbon nanotubes as hybrid reinforcements

Magnesium based hybrid composites containing nano-sized silicon carbide and carbon nanotubes reinforcements with minimal porosity were successfully fabricated using powder metallurgy technique with microwave sintering and hot extrusion. It was found that the addition of nano-sized silicon carbide and carbon nanotubes reinforcements lowered the coefficient of thermal expansion of magnesium. Moreover, increasing presence of silicon carbide particles led to a progressive reduction in coefficient of thermal expansion for a constant overall amount of reinforcements indicating that carbon nanotubes lowered the coefficient of thermal expansion to a lesser extent when compared to silicon carbide. Micro-hardness, 0.2% YS and UTS (except for Mg+1%CNT) showed improvement, while failure strain decreased when nano-sized silicon carbide and carbon nanotubes were added to magnesium. The failure mode of magnesium and magnesium composites was predominantly brittle exhibiting the presence of cleavage steps.     

Influence of different post treatments on tungsten carbide-cobalt inserts

The present work is an attempt to improve some of the mechanical properties of cemented tungsten carbide (WC) cutting tool by subjecting it to different post treatments. The different post treatments that are tried out to the tungsten carbide-cobalt (WC-Co) inserts are a) controlled cryogenic treatment, b) heating and forced air cooling and c) heating and quenching in oil bath. The response of WC-Co inserts to such different post treatments has been evaluated in terms of microhardness, microstructural changes, scanning electron microscope (SEM) micrograph and Co metal phase changes through XRD. The experimental result indicate a remarkable response to all the above mentioned post treatments and the analysis of the same are presented in this paper.     

Crystallization, microstructure development and dielectric behaviour of glass ceramics in the system [SrO · TiO2]-[2SiO2 · B2O3]-La2O3

Various glasses in the system (65 – x)[SrO · TiO₂]-(35)[2SiO₂ · B₂2O₃]-(x)La₂O₃, where x = 1,5,10 (wt%) were prepared by melting in alumina crucible (1375–1575 K). Heat treatment schedules were selected from DTA plots of respective glasses. X-ray diffraction studies of glass ceramic samples containing different concentrations of La₂O₃ revealed the formation of Sr₂B₂O₅, Sr₃Ti₂O₇ and TiO₂ (rutile) phases. The addition of La₂O₃ results in the development of well formed, elongated crystallites of different phases. Results of the dielectric behaviour demonstrate higher values of dielectric constant for some of the glass ceramic samples. This can be ascribed to the relaxation polarization at the crystal-glass interface due to conductivity differences between crystalline and glassy phases.     

A study of dynamic meta-learning for failure prediction in large-scale systems

Despite years of study on failure prediction, it remains an open problem, especially in large-scale systems composed of vast amount of components. In this paper, we present a dynamic meta-learning framework for failure prediction. It intends to not only provide reasonable prediction accuracy, but also be of practical use in realistic environments. Two key techniques are developed to address technical challenges of failure prediction. One is meta-learning to boost prediction accuracy by combining the benefits of multiple predictive techniques. The other is a dynamic approach to dynamically obtain failure patterns from a changing training set and to dynamically extract effective rules by actively monitoring prediction accuracy at runtime. We demonstrate the effectiveness and practical use of this framework by means of real system logs collected from the production Blue Gene/L systems at Argonne National Laboratory and San Diego Supercomputer Center. Our case studies indicate that the proposed mechanism can provide reasonable prediction accuracy by forecasting up to 82% of the failures, with a runtime overhead less than 1.0 min.     

An indigenously developed electronic control system for Langmuir-Blodgett film deposition set-up

An indigenous and simple electronic control system for Langmuir-Blodgett (LB) film deposition set-up has been developed. This set-up consists of a microstepping circuit to drive the stepper motors with precision and smooth motion, essential for controlled movement of the barriers and substrate in the LB set-up. Linear variable differential transformer (LVDT)-based displacement measuring device has been developed and used to measure the surface pressure of the monolayer material spread on the water surface. A control program is written which incorporates all operational modes required to drive the set-up and to acquire the datain situ using a set of user-friendly commands. This control set-up has been successfully used to plot the pressure-area isotherm of various amphiphilic compounds such as ferric stearate, zinc arachidate etc. and for deposition of ordered LB films of ferric stearate.     

A new energy efficient, environment friendly and high productive texturization process of industrial multicrystalline silicon solar cells

A new texturization process based on a uniform, isotropic and slow removal of silicon, using a composition of sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl) solution at an elevated temperature is developed recently for multicrystalline silicon solar cells. This process is applied in optimized condition in regular industrial production line and it immediately replaces the old popular industrial process of texturization using a combination of NaOH solution, alcoholic NaOH solution and hydrochloric acid solution in different steps at a higher temperature. Also the gain in solar cell efficiency at global AM1.5 spectrum, 1 SUN intensity condition is nearly 10% in final value. In addition, it has become finally an energy efficient and environment friendly texturization process for large area multicrystalline silicon solar cells for commercial use. In this paper the cost effectiveness and environment friendly aspects of the proposed process have been studied in detail along with the surface texture analysis of wafers with SEM and AFM micrographs to substantiate the reasons behind the above facts.     

Antibacterial Activity of the Sponge Ircinia Ramosa: Importance of its Surface-Associated Bacteria

Variations in the antibacterial activity of the sponge Ircinia ramosa were evaluated during two collection periods (January and May) against vicinity fouling bacteria (VFB) and sponge surface-associated bacteria (SAB). The density of fouling bacteria in the water column, as well as epibacterial abundance on the sponge surface, was enumerated during both collections, and both increased in the warmer month of May. The extracts obtained from SAB were also tested for their role in antibacterial activity of the host. Sponge-associated bacteria are capable of producing antibacterial metabolites. The antibacterial activity that originated from polar fractions in the cooler month of January shifted towards the nonpolar fractions in May. Nonpolar fractions were more useful for the sponge when threatened with increased bacterial density. Thus, the chemical nature and production of antibacterial compounds produced by sponge or its associated bacteria appears to be governed by the environment. An inverse relationship was observed between the epibacterial abundance over the sponge surface in nature and the antibacterial activity displayed by the sponge extracts in laboratory bioassays. This investigation reveals the importance of collection period as well as the role of associated bacteria in the evaluation of antibacterial activity.     

Influence of Rheological Behavior of Purely Viscous Fluids on Analytical Residence Time Distribution in Straight Tubes

In an effort to better understand the homogeneity of heat treatment of foodstuffs in holding tubes, the cumulative residence time distribution function is derived for a Herschel‐Bulkley fluid from fully developed laminar flow in a straight circular tube under isothermal conditions when diffusional effects are negligible. The proposed analytical solution can be reduced to solutions for Newtonian, shear‐thinning, dilatant, Bingham fluids by setting particular rheological parameters, and consequently, it is possible to successfully explain the dependence of residence time distribution on fluid properties for almost all of the rheological models used for time‐independent purely viscous fluids.