modern research physics

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The effects of cadmium and iron interaction on some physiological parameters in rice (Oryza sativa L.cv.fajr) plant were studied. The four days old seedlings were transferred to pots containing sand, irrigated with Hoagland solution in growth chamber. The 15 days old plants were treated with 0, 50 and 100 &muM  CdCl2 supplemented with 5, 10 and 20 ppm Fe as Fe-EDTA. Plants were grown under controlled condition and harvested after 30 days for measurements of some biochemical and physiological parameters. Treatments were conducted with four replications. Under Cd stress, growth of plant decreased. In plants treated with CdCl2, relative growth rate, net assimilation rate and photosynthetic rate were decreased. Addition of Fe-EDTA (10 and 20 ppm) moderated cadmium effects. Under Cd stress without Fe, respiration rate and CO2  compenstation point increased, however, in solutions containing both CdCl2 and Fe-EDTA, respirations rate and CO2  compenstation point decreased. In plants treated with CdCl2, catalase activity increased. However, after increasing Fe in solution containing CdCl2, catalase activity decreased. Therefor, the results indicated that in CdCl2 treated plants with increasing Fe-EDTA, the toxic effects of Cd decreased.

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Conducting polyaniline (PANI) nano particles doped with HCl were synthesized by a sonochemical method. Polyaniline/Poly (styrene- alt-maleic acid)/Polystyrene sulfonic acid nano composites with different polyaniline content were developed by solution-dispersion blending method. The influence of Poly (styrene-alt-maleic acid) (PSMAC) and polystyrene sulfonic acid (PSS) concentration in nano composite structure was investigated. The composite dispersed solution in tetrahydrofurane (THF) cast to fabricate conductive films with evaporation of the solvent. With only a mixing procedure and without any dispersant added, the PANI nanoparticles were well dispersed in the matrix polymer as indicated by scanning electron microscopy (SEM) images. The conductivity of obtained nano composites was measured with four probe technique. All of obtained nano composites have conductivity and between them, the maximum electrical conductivity was 3 S/cm. The obtained nano composites were characterized by FT-IR and UV-Vis spectroscopiess.

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In the present study, the effects of indole acetic acid (IAA) on certain physiological and biochemical parameters in Glycine max (L.) Merr under aluminum chloride (AlCl₃)stress were studied. Seeds were sterilized and cultured in petri-dishes. Six days old seedlings were transferred to pots, and then they were irrigated with Hoagland solution in a growth chamber (with 16 h light period per 24 h, with day / night temperatures of 25/18 ºC respectively). Twenty days old plants were treated with different concentrations of AlCl₃ (0, 50, 100, 200 and 300 µM) and IAA (0, 50 and 100 µM). Plants were harvested 15 days after treatment. The plants exhibited decline in the relative water content (RWC), protein, soluble sugars, the chlorophylls a and b, carotenoids contents and photosynthetic rate with increase of aluminum chloride concentration, but the respiration rate and CO₂ compensation concentration were increased. With addition of IAA to culture solutions containing aluminum, the plants showed further decrease in the amount of soluble sugars, chlorophylls a and b, carotenoids and photosynthetic rate and further increase in other parameters. With increasing of aluminum concentration to culture solutions with and without IAA unsoluble sugars, proline and lipid peroxidation increased.
 

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In order to understand some physiological mechanism of chilling and cold sensitivity in plants we investigate the effects of chilling and cold stress on chlorophyll and proline content, lipid peroxidation and variable chlorophyll fluorescence (Fv/Fm) of Arabidopsis (thaliana L.) The four weeks-old plants (WT, and four chilling sensitive mutants [chs2-2], [chs2-1], [chs1-2] and [chs1-1]) were subjected to two different low temperature treatments (control (23^̊ C), chilling (13^̊ C) and cold (4^̊ C)), for one week. Fv/Fm and chlorophyll content changed significantly in all mutants except in WT by chilling stress (13^̊ C), compared with control and 4^̊ C treatments. Two out of four mutants, chs1-1 and chs1-2, had lowest chlorophyll content and Fv/Fm value among the tested genotypes. The proline content increased in all mutant genotypes, as well as in WT by chilling stress and 4^̊ C, compared with control. MDA content of shoots changed dramatically in all mutant genotypes except in WT by chilling stress, compared with control and 4^̊  C treatments. Our findings showed that two mutants, chs1-1 and chs1-2, have had highest chilling sensitivity among the tested genotypes and had the highest proline and MDA contents. It is possible that some damages in photosynthetic systems and/or in proline metabolism via mutation cause these plants more sensitive to chilling and cold stress