Treatment of electroplating wastewater containing Cu2+, Zn2+ and Cr(VI) by electrocoagulation

The performance of electrocoagulation, with aluminium sacrificial anode, in the treatment of metal ions (Cu2+, Zn2+ and Cr(VI)) containing wastewater, has been investigated. Several working parameters, such as pH, current density and metal ion concentrations were studied in an attempt to achieve a higher removal capacity. Results obtained with synthetic wastewater revealed that the most effective removal capacities of studied metals could be achieved when the pH was kept between 4 and 8. In addition, the increase of current density, in the range 0.8-4.8 A dm(-2), enhanced the treatment rate without affecting the charge loading, required to reduce metal ion concentrations under the admissible legal levels. The removal rates of copper and zinc were found to be five times quicker than chromium because of a difference in the removal mechanisms. The process was successfully applied to the treatment of an electroplating wastewater where an effective reduction of (Cu2+, Zn2+ and Cr(VI)) concentrations under legal limits was obtained, just after 20 min. The electrode and electricity consumptions were found to be 1 g l(-1) and 32 A h l(-1), respectively. The method was found to be highly efficient and relatively fast compared to conventional existing techniques.     

CaS: Bi as U.V. dosimeter

Stable CaS: Bi phosphors have been prepared under optimum reducing conditions. These phosphors exhibit two thermoluminescence peaks at 60° and 200°C, except at very low or high concentrations of the dopant. The use of the high temperature (dosimetric) peak in CaS: Bi (0.05%) has suggested for monitoring ultraviolet doses without any pre-irradiation. The effects of annealing, fading, dose response and monochromatic excitation have also been studied.     

Synthesis and characterization of bismuth doped barium sulphide nanoparticles

We have synthesized BaS:Bi nanocrystalline powder of average grain size 35 nm by solid-state diffusion method using sodium thiosulphate as a flux. During this work we have optimized the nature and amount of flux, amount of the dopant and temperature of firing for maximum yield of photoluminescence. The samples were characterized by X-ray powder diffraction (XRD) method, transmission electron microscopy (TEM), photoluminescence (PL) and UV-visible techniques. On excitation by 425 nm, these nanophosphors give one emission peak at 575 nm which corresponds to green color. In the excitation spectra of these particles there are two peaks at 350 nm and 425 nm. The effect of dopant concentration on the photoluminescence of BaS:Bi nanocrystallites has been studied which is in agreement with the principle of concentration quenching. The energy band gap of bismuth doped BaS nanopowder has been calculated to be 4.25 eV and is blue shifted in comparison to their bulk counterparts. The blue shift may be due to the quantum confinement in the particles.     

Effect of solvent-induced structural modifications on optical properties of CdS nanoparticles

We have investigated the effects of solvent used during synthesis on structural and optical properties of CdS quantum dots. Different methods of synthesis for the production of CdS quantum dots are presented. These are: (a) wet chemical co-precipitation in non-aqueous medium (i.e. methanol); (b) wet chemical co-precipitation in aqueous medium (deionized water) and (c) solid state reaction. It is demonstrated that the use of methanol as solvent leads to a strong enhancement of PL intensity of CdS quantum dots for use in optoelectronic devices. These products were characterized by X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The change in bandgap with size-quantization was investigated by UV-VIS absorption spectroscopy. CdS nanocrystals prepared in non-aqueous medium have narrow size distribution than those prepared in aqueous medium and solid state reaction. Phase transformation of CdS nanocrystals from a cubic to hexagonal structure was observed in methanol solution. The formation of CdS/Cd(OH)₂ nanostructure was also confirmed using X-ray diffraction pattern. This suggests that the strong enhancement of the PL intensity may have originated from the remarkable reduction of non-radiative recombination process, due to surface defects of quantum dots. The red shift of the Raman peaks compared to that for bulk CdS may be attributed to optical phonon confinement.     

Mutations in the PIG-A gene causing paroxysmal nocturnal hemoglobinuria are mainly of the frameshift type

Paroxysmal nocturnal hemoglobinuria is an acquired hemolytic anemia associated with somatic mutations in the X-linked gene PIG-A, which encodes a protein involved in the biosynthesis of glycosyl phosphatidylinositol anchors. To further elucidate the molecular basis of paroxysmal nocturnal hemoglobinuria, we have worked out a systematic and relatively rapid methodology to scan for mutations in the entire coding region of the PIG-A gene. By this methodology, we have identified 15 different somatic mutations in 12 patients. The mutations were spread throughout the entire PIG-A-coding region. Of the mutations, 10 caused frameshifts, 6 caused small deletions, 3 caused small insertions, and 1 caused deletion-insertion. Five single base pair substitutions caused three missense mutations, one nonsense mutation, and one defect in the donor splice site of intron 4. In each of 3 patients, two independent mutations were identified. The predominance of frameshift mutations may reflect selection for somatic mutations giving rise to clones with a completely nonfunctional PIG-A protein.     

Thermoluminescence response of CaS:Bi nanophosphor exposed to 200 MeV Ag ion beam

A study of the thermoluminescence (TL) parameters has been performed on swift heavy ion exposed Bi³⁺ doped CaS nanophosphors prepared by the chemical co-precipitation method. All the samples have been exposed to 200 MeV Ag⁺¹⁵ ions in a fluence range of 1 × 10¹²–1 × 10¹³ ions/cm². The prominent TL glow peak at 403 K (observed for the γ-irradiated sample) appeared at the same position in the 200 MeV Ag⁺¹⁵ ion beam irradiated samples, while the other peak at 466 K disappeared and the broad peak normally measured at 534 K split into two peaks at 535 K and 582 K for the Ag⁺¹⁵ ion beam irradiated samples. The effect of different Bi³⁺ concentration has been investigated and it was found that the maximum TL intensity was measured for the 0.08 mol% sample. The effect of different heating rates on the TL response has also been determined. The trapping parameters (i.e. activation energy, frequency factor, order of kinetic) of all the individual peaks of the glow curves have been analysed by using Chen’s formulae. The low fading and linear TL response in the range of 1 × 10¹²–1 × 10¹³ ions/cm² will be helpful to explore the potential use of this material for heavy ion dosimetry.     

A knowledge-oriented meta-framework for integrating sensor network infrastructures

In this paper, we describe a meta-framework that helps guide development of sensor network (SN) cyberinfrastructure in a way that enables emerging sensor infrastructures, including advances in sensor hardware, communication, monitoring applications, and knowledge representation, to interoperate. This framework is guided by the DAST principle. That is, the overall goal of any SN infrastructure is essentially the same: to acquire the right Data from the right Area using the right Sensors at the right Time. In conformity with this principle, our meta-framework integrates SN infrastructures along axes related to the answers to five questions: Why has processing been requested? What are the goals of the processing? Where is it carried out? How is it carried out? And, when will the results be provided? The infrastructure components are integrated by using various data standards and technologies currently available from various SN research groups, and mapping them to an overarching knowledge-based meta-framework. In concrete terms, we show in this paper how four distinct sensor technology projects under development in our research lab are used to fit these five axes of SN infrastructure and how they can be indirectly integrated through the use of software agent-based tools, which embody the meta-framework: an ontology-based decision support system that applies models of SN infrastructure to its evaluation techniques; SN configuration tools that enable network configurations to be exported into common geospatial standards; a transformation engine that converts these SN configurations, along with collected data, into a representation that meshes with our infrastructure models so that they may be used within our decision support environment; and a Virtual SN to handle many of the management and control aspects of SNs.     

New somatic mutation in the PIG-A gene emerges at relapse of paroxysmal nocturnal hemoglobinuria

We report a detailed longitudinal study of the first patient to be treated (in 1973) for paroxysmal nocturnal hemoglobinuria (PNH) with syngeneic bone marrow transplantation (BMT). The patient subsequently relapsed with PNH in 1983, and still has PNH to date. Analysis of the PIG-A gene in a recent blood sample showed in exon 6 an insertion-duplication causing a frameshift. Polymerase chain reaction (PCR) amplification of the PIG-A exon 6 from bone marrow (BM) slides obtained before BMT showed that the duplication was not present; instead, we found several single base pair substitutions in exons 2 and 6. Thus, relapse of PNH in this patient was not due to persistence of the original clones; rather, it was associated with the emergence of a new clone. These findings support the notion that the BM environment may create selective conditions favoring the expansion of PNH clones.     

Tartrazine modified activated carbon for the removal of Pb(II), Cd(II) and Cr(III)

A two in one attempt for the removal of tartrazine and metal ions on activated carbon has been developed. The method was based on the modification of activated carbon with tartrazine then its application for the removal of Pb(II), Cd(II) and Cr(III) ions at different pH values. Tartrazine adsorption data were modelled using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacities qm were 121.3, 67 and 56.7mgg(-1) at initial pH values of 1.0, 6.0 and 10, respectively. The adsorption of tartrazine onto activated carbon followed second-order kinetic model. The equilibrium time was found to be 240min at pH 1.0 and 120min at pH 10 for 500mgL(-1) tartrazine concentration. A maximum removal of 85% was obtained after 1h of contact time. The presence of tartrazine as modifier enhances attractive electrostatic interactions between metal ions and carbon surface. The adsorption capacity for Pb(II), Cd(II) and Cr(III) ions has been improved with respect to non-modified carbon reaching a maximum of 140%. The adsorption capacity was found to be a pH dependent for both modified and non-modified carbon with a greater adsorption at higher pH values except for Cr(III). The enhancement percent of Pb(II), Cd(II) and Cr(III) at different pH values was varied from 28% to 140% with respect to non-modified carbon. The amount of metal ions adsorbed using static regime was 11-40% higher than that with dynamic mode. The difference between adsorption capacities could be attributed to the applied flow rate.