Biological leaching of nickel and cobalt from lateritic nickel ore of Sukinda mines

In the present study lateritic nickel ore was used for bacterial leaching using a mixed consortium of mesophilic acidophiles. The microorganisms were adapted to 1 gram nickel/L prior to leaching. For the experiments, lateritic ore in different forms such as raw, roasted, roasted ore presoaked in dilute sulphuric acid and palletized pretreated roasted (400 °C and 600 °C) ore were taken. The leaching experiments were conducted in 9 K+ with 40 L capacity bioreactor using 10% (v/v) inoculum concentration at 10% (w/v) pulp density. The aeration was maintained at 2–3 L/min and the speed of agitator and temperature at 400–500 rpm and 35 °C. The maximum extraction of nickel and cobalt was observed with pretreated ore (600 °C) at 10% pulp density (77.23% and 73.22%) respectively within 31 days at pH 1.5 and least extraction in case of raw ore i.e., 9.47% nickel and 41.12% cobalt respectively.     

Bio-dissolution of copper from Khetri lagoon material by adapted strain of Acidithiobacillus ferrooxidans

Bioleaching involves the use of iron and sulfur oxidizing microorganisms to catalyze the dissolution of valuable metals. In this investigation, lagoon material contains 0.39% Cu, in which the major copper bearing mineral is chalcopyrite associated with other minerals present as minor phase. Leaching experiments were carried out using an adapted strain of Acidithiobacillus ferrooxidans with various parameters such as presence/absence of iron, pH, pulp density and temperature. Base of the medium was 9 K (without ferrous) Bio-dissolution of copper was found to be maximum, i.e., 80.9% with 9 K⁺ (with ferrous) at pH-2.0, 10% pulp-density and 35 °C within an incubation period of 30 days.     

Synthesis of Silicon Carbide from Rice Husk in a Packed Bed Arc Reactor

Silicon carbide in the form of powder was prepared from boiler burnt rice husk in a new type of packed bed arc reactor where the raw materials were processed in briquette form. X-ray diffraction analysis identified the presence of both β and α SiC. Microstructural characterization revealed the presence of triangular, truncated triangular, and hexagonal crystallites, along with platelets.     

Studies on sulphatization—I. Sulphatization of manganese ore with pyrite

The sulphatization of low grade manganese ore with iron pyrites has been studied. The effect of reaction period, temperature, ratio of manganese to sulphur, particle size, surface area and packing density was investigated and the extent of sulphatization was reported as recovery of manganese sulphate. Under optimum heating time of 2 h at 600°C with finely powdered (?150±200 mesh BSS pyrite and ?300±325 mesh manganese ore) reactants, the conversion to manganese sulphate was 82%.     

EM-index: a new measure to evaluate the scientific impact of scientists

During the last decade, several scientometrics as well as bibliometrics indices were proposed to quantify the scientific impact of individual. The h-index gives a breakthrough in scientific evaluation, but this index suffers with big hit problem, i.e., once a paper is selected in h-core publication, further citation of h-core articles is not considered in scientific evaluation. To overcome this limitation of h-index, the e-index was proposed, but it does not consider the core citation count. It considers only the excess citation count. To overcome this limitation, the EM-index is proposed in this article. The EM-index is the extension of h-index and e-index, which uses the concept of multidimensional h-index. The EM-index uses all citation counts of h-core articles at multi-level to quantify the scientific impact of the individual. But this index does not consider all publication citations. To overcome this limitation of EM-index a multidimensional extension of the EM-index is also proposed called EM′-index. To validate the proposed indicators, an experimental analysis has been done on 82 scientist’s publication citation count, who are working in scientiometrics field. In such a way, we found a more balanced and fine-grained approach to evaluate the scientific impact of individual as well as to compare the scientific impact of two different researchers/scientists.

     

Investigation of the denitrification activity of immobilized Pseudomonas butanovora cells in the presence of different organic substrates

An investigation was made of the effects of variation of the hydraulic retention time (HRT) and the concentrations of three different carbon sources (succinic acid, ethanol and acetic acid) on the denitrification activity of immobilized Pseudomonas butanovora cells. The highest denitrification activity was in all cases measured at a C: N ratio of 6: and a relatively low HRT (2.5 h). The highest denitrification rates were 1.17 kg NO3--N m(-3) d(-1) for succinic acid, 1.63 kg NO3--Nm(-3) d(-1) for ethanol and 1.53kg NO3--Nm(-3) d(-1) for acetic acid. At the same C:N ratios, ethanol and acetic acid proved to be better substrates for the reduction of nitrate and nitrite. The determined optimum C: N ratios were 1.78 +/- 0.31, 0.95 +/- 0.17, 1.76 +/- 0.42 for succinic acid, ethanol and acetic acid, respectively. The optimum C:N ratios for the different substrates did not change in response to an increased flow rate. At a C: N ratio of 3:1 and a HRT of 1.5 h, the immobilized cells did not retain their activity. Apart from the difference in the effectivity between the electron donors, the main influence on the denitrification rate was exerted by the flow rate The results of this study demonstrated that Pseudomonas butanovora can utilize all three of these carbon sources to achieve a high rate of denitrification.     

DNA damage by benzo[a]pyrene in the liver of mosquito fish Gambusia affinis

Exposure of Gambusia affinis to water containing different concentrations of benzo[a]pyrene (BaP) causes an increase in benzo[a]pyrene monooxygenase (BPMO) activity which reaches a maximum on the second day. Concomitantly, the DNA is altered in such a way that nuclease S1-sensitive sites (SSS) become measurable. The size distribution of liver DNA treated with nuclease S1 in control fish shows two populations of DNA by length, with means of 30 X 10(6) and 60 X 10(6) Daltons, respectively. In fish treated with 100 ppb BaP, the population with longer molecules of DNA disappears and shorter molecules increase in number. This may be explained in terms of the introduction of an additional 0.31-0.46 DNA nicks per control DNA molecule caused by metabolically activated BaP derivatives.     

Percolation bacterial leaching of low-grade chalcopyrite using acidophilic microorganisms

Bioleaching studies were carried out in percolation columns using low-grade copper containing rock (granite). The lixiviant consisted of acidified ferric sulfate containing acidophilic microorganisms. The iron oxidizing strain was isolated from Malanjkhand mine water and after adaptation the iron oxidation observed to be 500 mg/L/h. Leaching parameters studied were lixiviant flow rate, particle size and bed height. It was observed that leaching efficiency increased with decrease of particle size and lixiviant flow rate. The precipitation of iron during leaching observed to be low as pH was maintained at 2. Based on the leaching kinetics, a unified rate equation was developed and shown as rά(d _p )^−0.61 (F)^−0.76 (H _b )^0.97.     

PAH content, toxicity and genotoxicity of coastal marine sediments from the Rovinj area, Northern Adriatic, Croatia

Surface marine sediments collected from 8 sampling sites within the Rovinj coastal area, Northern Adriatic, Croatia, were used for determining priority pollutant polycyclic aromatic hydrocarbons (PAHs) and toxic/genotoxic potential of sediment organic extracts. Total PAH concentrations ranged from 32 microg/kg (protected area) to 13.2 mg/kg dry weight (harbor) and showed clear differences between pristine, urban industrial and harbor areas. PAHs distribution revealed their pyrogenic origin with some biogenic influence in harbor. At all sampling sites sediment extracts showed toxic potential that was consistent with the sediment type. No correlation between toxicity measured by Microtox assay and concentrations of individual or total PAHs was found. Noncytotoxic dose of sediment extracts showed no genotoxic potential in bacterial umu-test. DNA damage is positively related to total PAHs at 4 sampling sites (S-1, S-2, S-3, S-6), but the highest DNA damage was not observed at the site with the highest total sediment PAH content (S-5).     

Plant-Growth-Promoting Rhizobacteria Emerging as an Effective Bioinoculant to Improve the Growth,Production, and Stress Tolerance of Vegetable Crops

Vegetable cultivation is a promising economic activity, and vegetable consumption is important for human health due to the high nutritional content of vegetables. Vegetables are rich in vitamins, minerals, dietary fiber, and several phytochemical compounds. However, the production of vegetables is insufficient to meet the demand of the ever-increasing population. Plant-growth-promoting rhizobacteria (PGPR) facilitate the growth and production of vegetable crops by acquiring nutrients, producing phytohormones, and protecting them from various detrimental effects. In this review, we highlight well-developed and cutting-edge findings focusing on the role of a PGPR-based bioinoculant formulation in enhancing vegetable crop production. We also discuss the role of PGPR in promoting vegetable crop growth and resisting the adverse effects arising from various abiotic (drought, salinity, heat, heavy metals) and biotic (fungi, bacteria, nematodes, and insect pests) stresses.