Extractability and phytotoxicity of heavy metals present in petrochemical industry sludge

Bioavailability of heavy metals present in industrial sludges and their subsequent phytotoxicity are crucial parameters to assess the associated health hazards and suitability for land application. The present study is an effort to determine the extractability of heavy metals present in different phases of the sludges, coming out of two different operations involved in petrochemical industry viz. spent caustic treatment (SCT) and waste water treatment (WWT) following the BCR sequential extraction procedure. The maximum amount of Cd and Cu was found associated with oxidizable phase, whereas Cr and Ni were best recovered in residual fractions of both the sludges. Maximum Pb was recovered in oxidizable and residual phase in the WWT and SCT sludges, respectively. The stabilization treatment undergone by sludges strongly influenced the heavy metal distribution and the phases to which they were associated. The total metal concentration in both the sludges did not exceed the limit set out by the European Legislation and was found as Cd = 0.449, Pb = 3.340, Ni = 6.530, Cr = 21.087, & Cu = 27.129 μg g^?1 and Cd = 0.549, Pb = 5.664, Ni = 7.161, Cr = 27.096, & Cu = 35.479 μg g^?1 in the SCT and WWT sludges, respectively. Phytotoxicity of the sludges was assessed against the germination index and the relative root and shoot growth. Sludge leachates did not adversely affect the seed germination and the early seedling growth of Mung (Phaseolus mungo) and Gram (Cicer arietinum), indicating that these metals were concentrated in the non-bioavailable fractions of sludges.     

B and also T lymphocytes migrate via gut lymph to all lymphoid organs and the gut wall, but only IgA+ cells accumulate in the lamina propria of the intestinal mucosa

In pigs the lymphocytes emigrating from the intestinal wall were collected by cannulating the lymphatics, labeled in vitro using a fluorescent dye and retransfused. The injection of 6.6+/-4.2 x 10(8) cells resulted in a labeling index between 1.5% in intestinal lymph, 0.2% in the spleen and lymph nodes, approximately 0.1% in the intestinal lamina propria and 0.003% in intraepithelial lymphocytes. About 25 % of the injected cells were present in the blood and 1 % was recovered in the lymph. T cells were found in similar proportions in the injected and the recovered cells in the organs (70-80%). The proportion of IgA+ cells among the immigrated cells in the intestinal lamina propria ranged from 5 to 8%, which in absolute numbers was up to 60% of the injected IgA+ cells. T and IgM+ cells did not show a higher accumulation in any organ. These experiments in conventional, unrestrained animals revealed that (1) T cells immigrate into the intestinal lamina propria, (2) preferential migration of IgA+ cells from gut lymph to the intestinal lamina propria is obvious under in vivo conditions and (3) the immigrated IgA+ cells represent a very small population which is difficult to detect when analyzed in relative numbers.     

Incoherent in-band crosstalk induced power penalty in amplified WDM networks: a comparative study using Gaussian and chi-squared probability density functions

An analytical expression for power penalty (PP) from the formula for bit-error rate is derived by employing saddle point approximation in the chi-squared probability distribution function. This theory differs from the earlier ones in that it takes into account the dominant signal-amplified spontaneous emission beat noise applicable for optically pre-amplified systems. Imperfect extinction ratio accounting for higher power penalties is also considered in the analysis. Results have been compared with the available experimental results for a low number of crosstalk sources and an excellent agreement has been found. Although Gaussian probability density function (pdf) is simple to analyse, PP calculated from this pdf for a low number of crosstalk sources fails to match with the experimental results.     

Simulation and analysis of Awerbuch–Peleg and GSM schemes for location tracking of mobile users

Mobile users are increasingly demanding full access to networked communications while they are on the move. Several studies have shown that the overhead incurred by the network to keep track of the current location of mobile users is considerably high. The methods currently used for location tracking incur heavy unnecessary costs by requiring that users update locations in their home networks after each move regardless of the distance at which the move occurs, and that all search attempts for a mobile user are first routed to that user's home network. The Awerbuch–Peleg scheme presents a formal model for location tracking which attempts to minimize the cost of local operations—both move and find operations—through the construction of a regional hierarchy. In this paper we present a performance evaluation of the Awerbuch–Peleg scheme. We also compare its performance to that of the GSM‐based location tracking scheme. It is found that the Awerbuch–Peleg scheme in general results in higher costs than the GSM scheme. The reason for this is found to be some unexpected properties of the read and write sets which are key components of the Awerbuch–Peleg scheme. Copyright © 2001 John Wiley & Sons, Ltd.     

Linear stability of convection in a vertical channel filled with nanofluid saturated porous medium

The convection in a vertical channel filled with a porous medium saturated by a nanofluid is studied numerically. The effects of Brownian motion and thermophoresis are incorporated in the model used for nanofluid. Also, the flow within the porous region is governed by Brinkman's equation. The generalized eigenvalue problem for the perturbed state is obtained from a normal mode analysis and solved using the Chebyshev spectral collocation method. The Rayleigh number is expressed as an implicit function of the wavenumber with other parameters. The critical wavenumber and the critical Rayleigh number are calculated for different parameters. The preferred modes under critical conditions are detected.     

Magnetization reversal mechanism of chemically synthesized linear chains of α-Fe nanospheres

Journal of Materials Science - We report upon synthesis of stable chains of magnetically aligned zero-valent α-Fe nanoparticles and investigation of their magnetization reversal mechanism. The...     

Kinetics of alkylation of phenol with methanol over Ce-exchanged NaX zeolite

The alkylation of phenol with methanol was investigated in vapor phase over a series of cerium-exchanged NaX zeolite with Ce loadings ranging from 0 to 10.43 wt%. The catalyst MX-4 with 8.86 wt% cerium was found to be the best one with total cresols selectivity of 72% at a temperature of 573 K and MeOH to phenol mole ratio of 4:1. The catalyst was also found to be quite stable in the operating range investigated. It was established that the stronger acid sties are required for C-alkylation compared to O-alkylation. From the study of the effects of various parameters, the optimum operating condition for highest cresols selectivity were determined as: MeOH to phenol mole ratio, 4:1; temperature, 623 K; space-time, 10.2 kg h/kgmole under atmospheric pressure. From the kinetic analysis of the experimental data, the apparent activation energy for the reaction was determined as 57.2 kJ/mole.     

Dielectric function and optical conductivity of TiOx (0.8

S Gokhale  SR Barman  DD Sarma 《Canadian Metallurgical Quarterly》1995,52(20):14526-14530

CONTINUOUS FRACTIONATION OF GLASS MICROSPHERES BY GRAVITATIONAL SEDIMENTATION IN SPLIT-FLOW THIN (SPLITT) CELLS

Split-flow thin (SPLITT) separation cells, consisting of submillimeter thick rectangular channels having now splitters at both inlet and outlet ends, were operated continuously using the earth's gravitational field as a driving force to prepare narrow fractions from polydisperse micron-size glass bead populations. Equations arc shown that make it possible to achieve a binary fractionation around a specified cutoff particle diameter by the control of inlet and outlet flowrates. Using a single separation cell, each narrow fraction was obtained by a two step fractionation. one dividing the panicle population around the upper desired limit and the other around the lower desired limit of particle diameters. The clean fractionation by SPLITT cell operation was verified by scanning electron microscopy, which also provided the mean particle diameter and the coefficient of variation for each fraction. The consistency of size distribution results was also examined by steric field-flow fractionation.     

Tailoring of nanozeolite NaX for enhanced removal of a phytoestrogen from its aqueous solutions

This study represents the application of nanozeolite NaX (NZX) synthesized by hydrothermal treatment without addition of any expensive structure directing agent for the highly effectual adsorption of biochanin A from aqueous solution. The characteristics and surface morphology of NZX were determined using FT-IR, SEM, TEM, BET, and XRD. The adsorption performance of NZX was analyzed at different conditions such as temperature, pH, contact time, adsorbent dose, and initial adsorbate concentration. The adsorption mechanism was well verified by pseudo-second-order kinetic and Redlich–Peterson isotherm models. The thermodynamic parameters revealed that the removal process was exothermic and spontaneous.