Effect of gamma radiation on wheat plant growth due to impact on gas exchange characteristics and mineral nutrient uptake and utilization

The experiment was conducted to determine the effect of gamma radiation on plant growth and development, flag leaf gas exchange characteristics such as net photosynthetic rate (P _N), stomatal conductance (g _s), and transpiration rate (E) and activity of key carbon and nitrogen assimilating enzymes like Rubisco, starch synthase (SS) and nitrate reductase (NR) in field grown wheat. Grains of cultivar PBW-343 were exposed to a ⁶⁰Co (Cobalt-60) gamma source at a dose range from 0 to 500 Gy (Gray). Gas exchange characteristics of flag leaf were measured using Infrared Gas Analyzer (IRGA), while mineral nutrients were analyzed spectrophotometrically. Our results show that an irradiation treatment, in general, caused an improvement in plant growth and yield characteristics such as shoot and root mass, root length and surface area, leaf area and chlorophyll SPAD index, tiller number and grain yield. However, irradiation exceeding 5 Gy reduced the magnitude of radiation advantage for most of the investigated physiological and biochemical traits. No germination was recorded at 500 Gy irradiation dose. A dose-dependant increase in shoot Fe in radiated plants up to 25 Gy reflected its higher plant root to shoot translocation which may yield micronutrient rich grains. At higher dose of 100 Gy, there was a drastic reduction in flag leaf membrane stability index (MSI), photosynthesis, Rubisco, NR, and nutrients like K, P, Mg, Fe, and Zn. Starch synthase enzyme activity was unaffected by gamma irradiation indicating that the negative effect of high dose (100 Gy) on the grain yield were caused by the adverse effect of radiation on the gas exchange attributes particularly photosynthesis, carbon, and nitrogen assimilation efficiency and the plant uptake of mineral nutrients. The study concludes that gamma radiation at a low dose (25 Gy or lower) stimulates, while a high dose (100 Gy and above) inhibits plant growth and development of wheat. The adverse effect at 100 Gy and beyond could be attributed to the poor carbon and nitrogen assimilation efficiency and the plant uptake of mineral nutrients, all of which are the ultimate determinant of plant health.     

Removal of environmental level of 239+240Pu and 241Am from groundwater by using humic coated colloidal suspension of goethite (α-FeO(OH))

In case of natural catastrophic nuclear accident scenario like Daiichi Nuclear Power Plant (NPP) Fukushima, Japan (11 March 2011) and industrial nuclear accidents like Chernobyl, USSR (March 1986), thousands of curies of activity goes in the public domain and contaminate the drinking water system in the area around the accidental zone. In view of this there is a need to evolve methodology for decontamination of the drinking water without compromising the drinking water quality. During this work humic coated colloidal suspension of geothite(α-FeO(OH)) followed by ultrafiltration were used to decontaminate the water having ^239+240Pu and ²⁴¹Am in the concentration range of 10–100 Bq L^?1. Polydispersive colloids of goethite were generated by controlled oxidation of FeSO₄ in the presence of NaOH. Size characterization, morphology and elemental profiling of goethite suspension and their aggregation with increase in the concentration of humic acid was studied by using dynamic light scattering and scanning electron microscope hyphenated with energy dispersive spectrometry. Experimental results clearly indicate preferential association of Pu and Am with goethite suspension dominated with 30 nm colloids. The impact of humus material on selectivity of Pu and Am by goethite was studied in the concentration range of 10–100 μg mL^?1 of humic acid. This selectivity is further enhanced linearly with the increase in concentration humic acid from 10 to 60 μg mL^?1 and thereafter it remains constant. Goethite suspension having a coating of 60 μg mL^?1 of humic acid was successfully utilized to decontaminate the water. Goethite suspension was separated from the groundwater using Ultra filtration cell with membrane having 500 NMWL (nominal molecular weight limit).     

Biosynthesis of silver nanoparticles using <Emphasis Type="Italic">Ocimum sanctum</Emphasis> (Tulsi) leaf extract and screening its antimicrobial activity

Development of green nanotechnology is generating interest of researchers toward ecofriendly biosynthesis of nanoparticles. In this study, biosynthesis of stable silver nanoparticles was done using Tulsi (Ocimum sanctum) leaf extract. These biosynthesized nanoparticles were characterized with the help of UV–vis spectrophotometer, Atomic Absorption Spectroscopy (AAS), Dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Transmission electron microscopy (TEM). Stability of bioreduced silver nanoparticles was analyzed using UV–vis absorption spectra, and their antimicrobial activity was screened against both gram-negative and gram-positive microorganisms. It was observed that O. sanctum leaf extract can reduce silver ions into silver nanoparticles within 8 min of reaction time. Thus, this method can be used for rapid and ecofriendly biosynthesis of stable silver nanoparticles of size range 4–30 nm possessing antimicrobial activity suggesting their possible application in medical industry.     

An analytical expression for Eg and Ag modes of pyrochlores

A general analytical expression has been derived for E_g and A_1g modes in terms of stretching and bending force constant for cubic pyrochlore structure compounds. The expression has been applied to different pyrochlore oxides accounting six stretching and four bending force constants. The calculation of E_g and A_1g mode has been carried out by using the earlier reported values of force constants for titanates, hafnates and stannates. The analytical expression can be applied to any pyrochlore structure compounds for evaluating and assigning E_g and A_1g mode if the interatomic force constants are already known.     

Design and the operational characteristics of a 16 µ CF4 laser

The design and the operational characteristics of a CO₂ laser pumped CF₄ laser developed at BARC are reported. Output energies of up to 20 mJ have been obtained at 615 cm⁻¹ with an absorbed energy conversion efficiency of 10%.     

Electrochemical Sensing of Chlorpyrifos,a Carcinogen Responsible for Breast Cancer,in Milk and Plasma of Lactating Mothers

In view of the increase in breast cancer cases at the global level, electrochemical sensing of the carcinogenic pesticide, chlorpyrifos (CPF) in breast milk is proposed. The determination is based on the nucleophilic substitution reaction of pralidoxime (PAM) with CPF. The proposed method offers a linear concentration range of 0.002 to 0.08 μmol/L. The limit of detection and limit of quantification was found to be 0.05×10⁻⁹ and 0.167×10⁻⁹M, respectively. The offered “unmodified edge plane pyrolytic graphite sensor” proved to be a better substrate than the earlier reported modified sensors. The limit of detection for the proposed method was found to be nearly fifty times lower than reported at modified electrodes. The interference study proved the adequate selectivity of the offered sensor. The sensor has good stability and reproducibility along with high sensitivity. The offered sensor is very useful for cancer hospitals, pesticide industries, and the study of environmental toxicity-related issues.     

Potentiometric sensor for the nanoscale monitoring of Ni2+ ion in environmental samples by the fabrication of coated pyrolytic graphite electrode based on a novel C–C-coupled compound

Novel ligand 5,5?-((3-nitrophenyl)methylene)bis(2,6-diaminopyrimidin-4(3H)-one) (L) was synthesised and characterised. Preliminary studies on L have showed that it has more affinity towards the Ni²⁺ ion. Thus, the L was used as the electroactive material in the fabrication of poly(vinyl chloride) (PVC)-based membrane sensors such as coated graphite electrode (CGE) and coated pyrolytic graphite electrode (CPGE). Several polymeric membranes were fabricated by incorporating L as ionophore, NaTPB as anion excluders and BA, 1-CN, DBP, DOP and o-NPOE as solvent mediators and their effect on potentiometric response studied. Comparative electroanalytical studies performed on the CGE and CPGE depict that the CPGE with optimised membrane composition of L:PVC:o-NPOE:NaTPB in the ratio of 7:33:58:2 (w/w, mg) exhibited the best response in terms of wide working concentration range from 2.0 × 10^?8 to 1.0 × 10^?1 mol L^?1, (3.64 µg L^?1 –18.2 g L^?1) lower detection limit of 8.1 × 10^–9 mol L^?1 (1.47 µg L^?1) with Nernstian compliance of 29.4 ± 0.2 mV decade^?1 of activity of Ni²⁺ ion in the pH range of 3.5–9.0. The sensor can work satisfactorily in water–acetonitrile and water–methanol mixtures. It can tolerate 30% acetonitrile and 20% methanol content in the mixtures. The sensor showed fast response time of 8 s and could be used successfully for a period of 4 months. The sensor reflects its utility in the quantification of Ni²⁺ ion in real samples and has been successfully employed as an indicator electrode in the potentiometric titration of Ni²⁺ ion with EDTA.     

A statistical approach using L<Subscript>25</Subscript> orthogonal array method to study fermentative production of clavulanic acid by <Emphasis Type="Italic">Streptomyces clavuligerus</Emphasis> MTCC 1142

Clavulanic acid is a naturally occurring antibiotic produced by Streptomyces clavuligerus. The present work reports on clavulanic acid production by Streptomyces clavuligerus MTCC 1142 using one-factor-at-a-time and L₂₅ orthogonal array. The one-factor-at-a-time method was adopted to investigate the effect of media components (i.e., carbon source, nitrogen source and inoculum concentration) and environmental factors such as pH for clavulanic acid production. Production of clavulanic acid by Streptomyces clavuligerus was investigated using seven different carbon sources (viz. glucose, sucrose, modified starch, rice-bran oil, soybean oil, palm oil, and glycerol) and six different nitrogen sources (viz. peptone, yeast extract, ammonium chloride, ammonium carbonate, sodium nitrate and potassium nitrate). A maximum yield of 140 μg/mL clavulanic acid was obtained in the medium containing soybean oil as a carbon source and yeast extract as nitrogen source. Subsequently, the concentration of soybean flour, soybean oil, dextrin, yeast extract and K₂HPO₄ were optimized using L₂₅ orthogonal array method. The final optimized medium produced 500 μg/mL clavulanic acid at the end of 96 h as compared to 140 μg/mL before optimization. Synthesis of precursor molecules as a metabolic driving force is of considerable importance in antibiotic synthesis. Attempts to increase the clavulanic acid synthesis by manipulating the anaplerotic flux on C₃ and C₅ precursors by supplementing the medium with arginine, ornithine, proline, valine, leucine, isoleucine, pyruvic acid and á-ketoglutarate were successful. Supplementing the optimized medium with 0.1 M arginine and 0.1 M leucine increased the yield of clavulanic acid further to 1100 μg/mL and 1384 μg/mL respectively.     

Chitosan impregnated Ca-alginate: a new hybrid material for removal of uranium from potable water

Novel sorbent, chitosan impregnated calcium alginate (Cal-Alg-Chi) bead was developed to sorb uranium from potable water without compromising water quality parameters. The uptake study in batch mode, showed more than 98% sorption of uranium in the concentration range of 0.1–50 µg mL⁻¹. Cal-Alg-Chi beads, reduced the concentration of uranium below 15 ng mL⁻¹ from 100 to 450 ng mL⁻¹ in groundwater collected from effected regions in India. Sorption isotherm followed Langmuir model and maximum sorption capacity was evaluated as 36.04 mg g⁻¹. The sorption was endothermic with ΔG ⁰ value of −9.76 kJ mol⁻¹ and kinetics followed pseudo-second order rate law.