Antioxidant potential of Indian medicinal plant in Phyllanthus amarus L. under supplementary UV-B radiation

The stratospheric ozone depletion and enhanced solar ultraviolet-B (UV-B) irradiance may have adverse impact on living organism. The impact of UV-B radiation (UV-B, 280~320nm) on growth, biochemical and antioxidant enzymes activity was studied in Phyllanthus amarus (L.) seedling, commonly used as a green manure. The supplementary UV-B radiation significantly decreased the growth, development and changes in UV-B absorbing compounds such as anthocyanin and flavonoids. The antioxidant enzymes were unaffected and showed an enhanced activities in peroxidase, superoxide dismutase, Polyphenoloxidase and phenylalanine ammonia- lyase except catalase in UV-B irradiated seedling. Phyllanthus amarus seedling tries to counteract high level of reactive oxygen species produce under UV-B stress through the increased activities of antioxidant enzyme. We suggest that Phyllanthus amarus is resistant against UV-B radiation damage and the possible negative effect of additional UV-B radiation on the growth of seedling may have been effectively balanced by the UV-B radiation stress through increase in UV absorbing compound and antioxidant enzymes

Biochemical tolerance of Suaeda maritima L. (Dumort) as a potential species for phytoextracting heavy metal and salt in paper mill effluent contaminated soil.

Suaeda maritima is a halophyte that has been evolutionary adapted to cope with saline and heavy metal conditions. The aim of the present study was to examine the biochemical response of Suaeda maritima against phytoextracting heavy metals and salts from paper mill effluent. Suaeda maritima  seedlings have been grown for 120 days with an irrigation solution of 250 ml of 75% raw paper mill effluent after four drenching. Analysis of biochemical parameters revealed that maximum synthesis of chlorophyll, protein, phenol, proline and glycinebetaine may be involved in their ability to cope with heavy metal and salt stress. The present study confirms that the accumulation and increase of biochemical constituents can be considered as an efficient ROS scavenger and also maintain cellular homeostasis and metabolic functions in photosynthetically active leaves in Suaeda maritima, during phytoextraction studies. Keywords: phytoextraction, paper mill effluent, Suaeda maritima, biochemical, heavy metal and salt

Measurement of the Atmospheric Muon Spectrum from 20 to 3000 GeV

The absolute muon flux between 20 GeV and 3000 GeV is measured with the L3 magnetic muon spectrometer for zenith angles ranging from 0 degree to 58 degree. Due to the large exposure of about 150 m2 sr d, and the excellent momentum resolution of the L3 muon chambers, a precision of 2.3 % at 150 GeV in the vertical direction is achieved. The ratio of positive to negative muons is studied between 20 GeV and 500 GeV, and the average vertical muon charge ratio is found to be 1.285 +- 0.003 (stat.) +- 0.019 (syst.).Comment: Total 32 pages, 9Figure

Determination of defense mechanism in Phaseolus trilobus Ait. seedlings treated under UV-B radiation

Field studies were conducted to determine the role of defense mechanism in various parameters associated with plant protection subjected to UV-B radiation in Phaseolus trilobus Ait. commonly used as green manure and fodder. Spectrophotometric analysis showed that UV-B radiation decreases the chlorophyll content and increased the amount of UV-B absorbing compounds such as anthocyanins and flavonoids. Other UV-induced alterations included reduction in fresh weight and leaf area. However, wrinkling of leaves and increased leaf thickness was observed in UV-B treated seedlings. The antioxidant enzymes were unaffected and showed enhanced activity, except catalase in UV-B treated seedlings. These results suggest that, in general, UV-B radiation caused oxidative damage. However, plants have evolved complex mechanisms to scavenge the active oxygen species and thereby protect the cellular membrane, pigment and organelle.Des études sur le terrain ont été conduites pour déterminer le rôle du mécanisme de défense dans divers paramètres liés à la protection des plantes soumises au rayonnement UV-B dans le Phaseolus trilobus Ait. communement utilisé comme engrais verts et fourrage. L’analyse spectrophotométrique a prouvé que le rayonnement UV-B diminue le contenu en chlorophylle et augmente la quantité de composés absorbant l’UV-B tels que des anthocyanines et des flavonoïdes. D’autres altérations d’UV-induits ont inclus la réduction de poids à l’état frais ainsi que de la surface foliaire. Cependant, on a observé des feuilles ridées et un accroissement en épaisseur de feuilles des plantules traitées par UV-B. Les enzymes antioxydantes n’étaient pas affectées et ont montré une augmentation de leur activité, à l’exception de la catalase dans les plantules traitées au UV-B. Ces résultats suggèrent que, en général, le rayonnement UV-B cause le dommage oxydative. Cependant, les plantes ont développé des mécanismes complexes pour se débarrasser des espèces d’oxygène actif et ainsi protéger la membrane cellulaire, le pigment et organelle

Measurement of arrival time of particles in extensive air showers using TDC32

Arrival time of particles in an extensive air shower (EAS) is a key physical parameter to determine its direction. EAS direction is useful for studies of anisotropy and composition of cosmic rays, and search for multi-TeV γ-rays sources. Accurate timing may be used to search exotic phenomena such as production of new particles at extremely high energies available during early stages of development of EAS and also for detecting sub-relativistic hadrons in EAS. Time to digital converters (TDCs) are used to perform this task. Traditional TDCs operate in the START-STOP mode with limited dynamic range and single-hit capability. With the advent of high luminosity collider LHC, need for TDCs with large dynamic range, multi-hit capability and TRIGGERED mode of operation became necessary. A 32 channel TDC was designed for the GRAPES-3 experiment on a CAMAC platform around TDC32, an ASIC developed by micro-electronics group at CERN, Geneva. Four modules were operated in the GRAPES-3 experiment. Here, we present details of the circuit design and their performance over several years. The multi-hit feature of this device was used to study the time structure of particles in the EAS on time scale of ~1 μs. The distribution of time intervals in the multi-hit data shows an exponential profile with a time constant of ~370 ns. These delayed particles are likely to be neutrons produced in the EAS core that were recorded in the scintillator detectors following the relativistic EAS front