Puja Khare

Arsenic accumulation pattern in 12 Indian ferns and assessing the potential of Adiantum capillus-veneris, in comparison to Pteris vittata, as arsenic hyperaccumulator

The present study was undertaken to evaluate the ability of some Indian ferns to accumulate and tolerate arsenic. Twelve species of Indian ferns were exposed to 10 mg L(-1) arsenic as sodium arsenate for 15 days in hydroponic system. Depending on the arsenic uptake in the plant parts--Pteris vittata, Pteris cretica, Adiantum capillus-veneris and Nephrolepis exaltata may be categorised as arsenic accumulator. Further, A. capillus-veneris plants were grown in arsenic contaminated soil (200-600 mg kg(-1)) under green-house condition, to assess its arsenic accumulation and tolerance mechanism, in comparison to known As-hyperaccumulator--P. vittata Linn., growing in the same conditions. The experiment identified A. capillus-veneris having a potential to tolerate arsenic up to 500 mg kg(-1). The plants were analysed for the extent of oxidative stress, as a result of arsenic accumulation. A. capillus-veneris was able to detoxify the arsenic stress through induction of anti-oxidant defence system.

Structural Parameters of Perhydrous Indian Coals

Higher hydrogen content of perhydrous coals exhibits a different composition and physicochemical properties in comparison with normal coals. In the present investigation, a structural study of perhydrous coals and coke was done using FTIR and HPLC data. These coals have high volatile matter with high-calorific values and low-moisture content. The structural study suggests that the major structural units of these coals are simple phenols with para-alkyl substituted derivatives. They have high alkyl substitution groups and low aromatic compounds. The structural studies reveal that these coals contain high amounts of low-molecular weight PAH compounds with 1-2 ring structures. These 1-2 ring structures have high H/C ratios as compared to large ring polyaromatic hydrocarbons (PAHs). It may also be one of the reasons for high H/C ratios in these coals. The alkyl groups contribute significantly to their high volatile matter (VM) contents. The presence of alcoholic groups found in pyrolytic products may also be due to the conversion of catechol-like structures to those of cresols. Coal properties, such as moisture, VM, H/C ratio, and CV, do not correlate with the rank as normally classified. A definite relationship has been found between the characteristics of these coals, char/cokes, and aromatic characters (f a , Har).

Impact of biochar amendment on enzymatic resilience properties of mine spoils.

Soil enzymes are crucial for soil nutrient cycling function. Understanding of the factors that control their response to major disturbances such as dumping of environmentally toxic acidic waste remains limited. We evaluated the effect of dumping of overburden (OB) and their amendments using biochar, on the resistance and resilience of soil enzyme activities involved in phosphorus, nitrogen, sulphur and carbon cycling (acid & alkaline phosphatase, urease, arylsulphatase, dehydrogenase, phenol oxidases, cellulase and β-glucosidase). For investigation the soils treated with OB and with the mixture of OB and biochar were used for the cultivation of bacopa were used. We assessed 0 day, 45 day and 90 days activities of the target soil enzymes, available phosphorus, nitrogen, sulphur, soil organic carbon and microbial identification. The resilience and resistance index of all the treatments were calculated. We found that phyto-remediated OB-contaminated soil has its own resilience power. However, biochar addition enhanced the enzyme resistance and resilience of OB contaminated soil. In silico study indicates that biochar-Fe complex play a significant role in enzymatic activities. Overall, the results indicate a significant influence of phytoremediation and biochar addition on soil enzymatic activity that is extremely resistant to OB. This study provides insight on how biochar addition modulates soil biochemical and microbiological response to OB affected soils.

Nickel nanoparticles supported on reduced graphene oxide sheets: a phosphine free, magnetically recoverable and cost effective catalyst for Sonogashira cross-coupling reactions

In this study, we have developed a cost effective and one-pot strategy for the synthesis of a heterogeneous catalyst consisting of a Ni nanoparticle–reduced graphene oxide composite for Sonogashira cross-coupling reactions. Several characterization tools were employed to characterize the Ni nanoparticle–reduced graphene oxide composite, which indicated that magnetic Ni nanoparticles of a size range of 1–4 nm were uniformly anchored on the reduced graphene oxide nanosheets without using any surfactant or stabilizing agent. Different types of aryl halides and phenylacetylenes were coupled under the optimized reaction conditions with excellent yields to give biphenylacetylenes. The ferromagnetic behaviour of the Ni nanoparticle–graphene composite resulted in it being easily separable from the reaction mixture and the composite was reusable, up to six times, without losing its catalytic activity. The fresh as well as the reused catalyst for the Sonogashira cross-coupling reaction was well characterized using analytical techniques which showed that the Ni nanoparticles were well dispersed on the reduced graphene oxide nanosheets without agglomeration, and the size and morphology of the catalyst remained unchanged after use in the catalytic reaction.

Metabolic adaptation of Pteris vittata L. gametophyte to arsenic induced oxidative stress.

The sporophyte and gametophyte of Pteris vittata are arsenic hyperaccumulators, however, little is known about the mechanism by which the gametophyte deals with this toxic element. An in vitro system (spores grown in arsenic amended nutrient media) was used to investigate the impact of arsenic on growth of the gametophyte and the role of antioxidative systems in combating As-stress. When mature spores of P. vittata were grown in medium amended with 0-50 mg kg(-1) of arsenic (as arsenate), the arsenic concentration in the gametophyte increased, with increasing arsenate in the media, but did not inhibit the spore germination and biomass development. Increases in the level of antioxidant enzymes, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, and glutathione-Stransferase) and of ascorbic acid and glutathione probably enabled the gametophyte to withstand the oxidative stress caused by arsenate.

Mangiferin: A review of sources and interventions for biological activities.

Xanthones are naturally synthesized in various biological systems such as plants, lichens, and fungi and are stored as by‐products. In addition to taxonomic significance they are also important in the treatment/management of a number of human disorders. Mangiferin and its derived lead molecule have never qualified for use in a clinical trial despite a number of pharmacological studies that have proven its effectiveness as an antioxidant, analgesic, antidiabetic, antiproliferative, chemopreventive, radioprotective, cardiotonic, immunomodulatory, and diuretic. For centuries in the traditional practice of medicine in India and China the use of plants containing mangiferin has been a major component for disease management and health benefits. While it resembles biflavones, the C‐glucosyl xanthone (mangiferin) has great nutritional and medicinal significance due to its unique structural characteristics. The C‐glycoside link of mangiferin, mimicked to nucleophilic phloroglucinol substitution, facilitates its bioavailability and also is responsible for its antioxidant properties. Researchers have also utilized its xanthonic framework for both pharmacophoric backbone and for its use as a substitution group for synthesis and prospects. To date more than 500 derivatives using about 80 reactions have been generated. These reactions include: lipid peroxidation, phosphorylation, glycosylation, methylation, fermentation, deglycosylation, hydrolysis, polymerization, sulfation, acylation, etherification, peroxidation among others. Multiple studies on efficacy and safety have increased the global demand of mangiferin‐based food supplements. This review highlights the distribution of mangiferin in plants, its isolation, and assay methods applicable to different sample matrices. In addition we include updates on various strategies and derived products intended for designated pharmacological actions.

Comparative study of thermal properties of bio-coal from aromatic spent with low rank sub-bituminous coals.

In present investigation, biocoal samples were prepared from aromatic plant waste of two perennial grasses, i.e. Cymbopogon flexuosus (lemongrass) and Vetiveria zizanioides (khus) after oil extraction, root of Rosa damascene (rose), bark of Eucalyptus citriodora. These biocoals were characterized by proximate, ultimate, metal, thermogravimetric analysis (TGA), Fourier Transform Infra Red (FTIR) spectroscopy and ash analyses. Activation energies, initial temperature of devolatilization, maximum rate of weight loss (Rmax), fouling, slagging and alkali index were determined on the basis of TGA and ash analysis. These biocoals have good calorific values. There is possibility of slagging and fouling in combustion system but it is not severe. Owing to their similar fuel properties as high sulphur sub-bituminous coal, they can be good candidates for co-firing. Blending of these biocoals with high sulphur coals will serve dual purpose as (i) alternate fuel, and (ii) reduction in SO2 emission.

A simple and straightforward synthesis of substituted 2-arylbenzimidazoles over silica gel

A solid phase strategy for the synthesis of substituted 2-arylbenzimidazoles over silica gel has been achieved starting from their corresponding o-phenylenediamines 1 and aromatic aldehydes 2. The reaction is very simple, convenient and straightforward, and the products are obtained in moderate to high yields (49–91%).

The chemical composition of tertiary Indian coal ash and its combustion behaviour – a statistical approach: Part 2

In Part 1 of the present investigation, 37 representative Eocene coal samples of Meghalaya, India were analyzed and their physico-chemical characteristics and the major oxides and minerals present in ash samples were studied for assessing the genesis of these coals. Various statistical tools were also applied to study their genesis. The datasets from Part 1 used in this investigation (Part 2) show the contribution of major oxides towards ash fusion temperatures (AFTs). The regression analysis of high temperature ash (HTA) composition and initial deformation temperature (IDT) show a definite increasing or decreasing trend, which has been used to determine the predictive indices for slagging, fouling, and abrasion propensities during combustion practices. The increase or decrease of IDT is influenced by the increase of Fe2O3, Al2O3, SiO2, and CaO, respectively. Detrital-authigenic index (DAI) calculated from the ash composition and its relation with AFT indicates Sialoferric nature of these coals. The correlation analysis, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA) were used to study the possible fouling, slagging, and abrasion potentials in boilers during the coal combustion processes. A positive relationship between slagging and heating values of the coal has been found in this study.

Thermogravimetric Analysis of Perhydrous Indian Coals

In the present investigation, pyrolytic behavior of perhydrous Indian coals was evaluated using thermogravimetric analysis from 50 to 1,000°C. The devolatilization was classified into five major regions of thermal activity, i.e., dehydration of water, pre-plastic region, plastic range, secondary devolatilization, and contraction region. The values of activation energies in different regions indicate to follow different mechanisms during pyrolysis. Up to 850°C, different mechanisms, i.e., dehydration, desorption, devolatilization, and thermal degradation (tar and hydrocarbon formation), are the controlling steps. From 850°C, consecutive reactions like dehydrogenation, condensation, and contraction of carbon planes take place. These coals are of sub-bituminous rank; however, their activation energies for various regions are found to lie within the ranges reported for bituminous coals, which is due to their perhydrous nature.