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...     

Effect of bacterial inoculum ratio in mixed culture for decolourization and detoxification of pulp paper mill effluent

BACKGROUND: Effluent released from industry is a mixture of various pollutants. For the degradation of complex pollutants, mixed bacterial cultures can be more effective than a single culture. This study investigated the balance of bacterial populations in a mixed culture for maximum reduction of pollutants. RESULTS: This study deals with the degradation and detoxification of pulp paper mill effluent (PPME) by three bacterial strains, i.e. Serratia marcescens, Serratia liquefaciens and Bacillus cereus in different ratios, and found that two ratios, 4:1:1 and 1:4:1, were effective for the degradation of PPME. These ratios reduced the various pollution parameters. Enzyme bioassay revealed that more enzyme was produced during degradation for the ratio 4:1:1. High performance liquid chromatography (HPLC) analysis showed that the ratio 4:1:1 degraded 95% of lignin and related compounds, and chlorophenols up to 98%, whereas ratio 1:4:1 reduced lignin by 84% and chlorophenols by 58% after 7 days incubation. Degradation products were confirmed by gas chromatography–mass spectrometry (GC‐MS) analysis. A seed germination bioassay on Phaseolous mungo L. revealed that toxicity was reduced by the ratio 4:1:1. CONCLUSION: Due to variable potential of different bacteria show variation in their growth pattern at any contaminated site. This study shows that an appropriate ratio of mixed cultures is required for maximum degradation and detoxification of PPME. Copyright © 2012 Society of Chemical Industry     

Production and characterisation of bio-oil from Gold Mohar (Delonix regia) seed through pyrolysis process

Fast pyrolysis of the crushed Delonix regia seed was carried out in a semi-batch reactor at a temperature ranging from 400 to 650°C with an objective to produce bio-oil. The effect of temperature to obtain an optimum condition for maximum bio-oil yield and the composition of pyrolysis product were investigated. The maximum bio-oil yield was found to be 48?wt% at pyrolysis temperature of 600°C. The chemical composition of bio-oil obtained at optimum condition was analysed using Fourier-transformed infrared spectroscopy and Gas chromatography–mass spectrometry. The chemical analysis of the biofuel showed the presence of hydrocarbons in major, aldehydes, ketones, amides, nitriles, etc. The composition and fuel characteristics of the pyrolysis oil obtained in this work show that it may potentially be used as a renewable fuel and chemical feedstock.     

Chryseobacterium meningosepticum in a parapneumonic effusion in a chronic kidney disease patient on hemodialysis

Chryseobacterium meningosepticum is an uncommon human pathogen, which is an inhabitant of soil and water. It should be included in the list of suspected nosocomial infections, especially in patients with immunocompromised status. C. meningosepticum infections are not common but are clinically important because the organism is naturally resistant to multiple antibiotics. We report a case where the bacterium was isolated from the pleural fluid from a chronic kidney disease patient on hemodialysis, who developed pneumonia with complicated parapneumonic effusion. To the best of our knowedge, this is the first case where C. meningosepticum is isolated from the pleural effusion, from India.     

Homogenization for Dispersion and Reduction in Length of Carbon Nanotubes

An important aspect that limits the use of carbon nanotubes (CNTs) is the difficulty in obtaining homogeneously dispersed CNTs of uniform length. Hence, homogenization of multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) was carried out using bullet blender and the dispersion behavior was compared with that of ultrasonication. 1% sodium dodecyl sulphate (SDS), Triton-x-100 and polyethylene glycol 4000 were used as dispersing agents during homogenization. The dispersed CNTs were studied using transmission electron microscopy, ImageJ and Raman spectroscopy. Though dispersion and reduction in length of MWCNTs were observed both with ultrasonication and homogenization, lowest length range with about 75% reduction in polydispersity index was obtained on homogenization. Longer time of ultrasonication resulted in damage to small MWCNTs. Well dispersed and shorter MWCNTs were obtained with Triton-x-100 while reduction in length was minimum with SDS. SWCNTs of less than 1 μm length could be obtained by homogenization with Triton-x-100.     

Phytochemical Constituents,Attenuated Total Reflectance Fourier Transform Infrared Analysis and Antimicrobial Activity of Four Plant Leaves Used for Preparing Rice Beer in Assam,India

Phytochemicals content and antimicrobial activity of Artocarpus heterophyllus, Cyclosorus extensa, Oldendia corymbosa, and Alpinia malaccensis were investigated. Maximum alkaloids and terpenoids were found in A. heterophyllus; tannins and saponins in C. extensa; flavonoids, polyphenols, and phytosterols in O. corymbosa and anthraquinone, glycosides, and anthocyaninin A. malaccensis. Aqueous, methanolic, ethyl acetate, and hexane extracts were prepared from all the leaves. Attenuated total reflectance Fourier transform infrared spectrophotometric (ATR-FTIR) analysis revealed that alkanes and alkyl halides were prevalent in all the extracts and the ethyl acetate extracts contained comparatively higher number of functional groups, which were also more effective against Candida albicans, Escherichia coli, and Staphylococcus aureus. The minimum inhibitory concentration values of A. malaccensis against the tested pathogens were found to be lesser than the other species.     

Use of mesalime and electric arc furnace (EAF) dust as neutralising agents in biooxidation and their effects on gold recovery in subsequent cyanidation

The cost of lime/limestone for neutralisation is the second largest operating cost in bioleaching. Therefore, these studies have been conducted with the aim to investigate the possibilities for use of by-products such as mesalime and electric arc furnace (EAF) dust for neutralisation during biooxidation of a refractory gold concentrate. Experiments were carried out using a retention time of 57 h in a one-stage reactor and the influence of two industrial by-products on the biooxidation performance was evaluated. The neutralising capacity of EAF dust was lower, while the mesalime was similar to the Ca(OH)₂ reference. The arsenopyrite oxidation in experiments ranged from 85% to 90%, whereas the pyrite oxidation was 63–74%. In subsequent cyanidation, final gold recoveries of 90% were achieved in bioresidues from mesalime and Ca(OH)₂, while the EAF dust bioresidue had a recovery of 85%. A comparatively high elemental sulphur content in EAF dust probably encapsulates part of the gold, which explains the lower recovery for the EAF dust bioresidue despite a longer residence time. Cyanide consumption was relatively high and ranged from 8.1 to 9.2 kg/ton feed after 24 h of cyanidation. Overall, the by-products tested here have proved to be feasible options as neutralising agents in bioleaching operations.     

Phase Evolution,Magnetic, Optical,and Dielectric Properties of Zr‐Substituted Bi0.9Gd0.1FeO3 Multiferroics

Polycrystalline BiFeO₃ (BFO) and Bi_0.90Gd_0.10Fe_1?xZr_xO₃ (x = 0.0–0.10; BGFZ_x) ceramics were synthesized by solid‐state reaction method. Rietveld analysis of X‐ray diffraction patterns showed that BFO and BGFZ_x = 0.0 samples are stabilized in rhombohedral structure (space group R3c), whereas a small fraction of orthorhombic phase (space group Pn2₁a) is observed for BGFZ_{x = 0.03–0.10} samples. Suppression and disappearance of some Raman modes indicated a structural phase transition with addition of Zr dopant at Fe site. Magnetic measurements exhibited weak ferromagnetic behavior of BGFZ_x samples with increasing Zr⁺⁴ concentrations. The insertion of Gd⁺³ ions at Bi⁺³ sites and nonmagnetic Zr⁺⁴ ions at Fe⁺³ sites in Fe–O–Fe network suppressed the spin cycloid structure of BFO which in turn enhanced the magnetization of these ceramics. Electron spin resonance spectra revealed the breaking of spin cycloid of BFO due to the development of free spins with addition of Zr⁺⁴ dopants at Fe sites. UV–Visible diffuse reflectance spectra showed one d–d crystal field transition and two charge‐transfer (C–T) transitions along with a sharp absorption of light in visible region for all samples. Almost frequency‐independent dielectric constant and dielectric loss along with very low values of dielectric loss indicated greatly improved dielectric properties for BGFZ_{x = 0.03–0.10} samples.