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Abstract  

A method for the separation of carrier-free vanadium from scandium and bulk amount of titanium has been developed. Vanadium has been produced through the reactionnatTi(d,n)48,49V with 8 MeV deuterons from the Variable Energy Cyclotron, Calcutta. The separation is performed with Dowex 1×8, 50–100 mesh fluoride from anion exchange resin which retains all the scandium and titanium with 4.5M hydrofluoric acid as eluent, while vanadium(V) is easily eluted. The chemical yield of vanadium was >85%.

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Present study demonstrated the isolation of most promising β-galactosidase producing bacterial strain SB from soil. Morphological, biochemical, and 16s rRNA sequence analysis identified the bacterial strain as Arthrobacter oxydans. Several chemicals, including SDS, Triton X-100, Tween 20, isoamyl alcohol, and toluene-acetone mixture, were applied for extraction of intracellular β-galactosidase from the bacterial strain Arthrobacter oxydans. Among these, Tween 20 was recorded to be most effective. Role of pH, temperature, and shaker speed on production of β-galactosidase was evaluated using Box-Behnken design of response surface methodology. According to Box-Behnken analysis, optimum production of β-galactosidase (21.38 U (mg–1 protein)) is predicted at pH 6.76, temperature 36.1 °C, and shaker speed 121.37 r.p.m. The parameters are validated with the nearest value.

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Fusarium head blight (FHB) is a disease of small-grain cereals that has a proven negative impact on crop yield, quality and food safety. In this regard, it is one of the most studied diseases of small-grain cereals worldwide. This paper reports the commonly used artificial sources of inoculum and inoculation techniques employed in the study of FHB epidemiology. Spore suspensions and grain spawn are the most popular forms of artificial inoculums. Spray inoculation technique is more commonly used than the point inoculation technique for delivering the inocula to the target sites. Spray inoculation has an advantage over point inoculation in that it can be used to detect both Type I and II resistances to FHB, point inoculation can only detect Type II resistance to FHB. Grain spawn is the commonest soil-surface inoculum used in the study of FHB. Its advantage lies in the fact that it is capable of propagating inoculum over a long period of time compared to other methods. It can also detect the five types of resistances reported (Types I, II, III, IV and V). In order to gain further information regarding the epidemiology of FHB, researchers need to explore other potential sources of artificial inoculum.

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The effect of different timings of fungicide applications on Fusarium head blight severity and mycotoxin accumulation in wheat grain was investigated in two field experiments. The fungicides metconazole, tebuconazole, azoxystrobin and mixtures of metconazole + azoxystrobin and tebuconazole + azoxystrobin were applied either, 5 days pre-, 2 days pre-, 2 days post-or 5 days post-inoculation of wheat ears with Fusarium spp. and Microdochium spp. at GS 65. Fungicides applied 2 days pre-or 2 days post-inoculation were most effective at reducing Fusarium head blight severity and DON concentration in grain. Metconazole and tebuconazole applied alone within two days of inoculation were most consistent in their effects on Tri5 DNA and DON in harvested grain.

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Saprophytic microflora and non-toxin producing Microdochium spp. capable of causing Fusarium head blight (FHB) have been suggested to affect the development of FHB caused by Fusarium spp., the occurrence of mycotoxins and the efficacy of fungicides for the control of the disease. The effects of metconazole and azoxystrobin on the interactions between Fusarium culmorum and Microdochium spp., Alternaria tenuissima or Cladosporium herbarum on FHB symptom development, Tri5 DNA concentration and deoxynivalenol (DON) production were studied under glasshouse conditions. Results indicated that the sequence of infection of wheat heads and the relative timing of fungicide application can significantly affect FHB severity and the resulting mycotoxin contamination of harvested grain. Introduction of A. tenuissima, C. herbarum or Microdochium spp. to wheat heads at GS 57 before inoculation with F. culmorum at GS 65 generally resulted in increased FHB severity, Tri5 DNA and DON concentration in harvested grain. The greatest increases of FHB severity (266%), Tri5 DNA (79%) and DON (152%) were observed when Microdochium spp. were introduced first at GS 57 and F. culmorum inoculation followed at GS 65. Metconazole generally reduced FHB severity, Tri5 DNA and DON concentration in grain but azoxystrobin was most efficient at reducing DNA of Microdochium spp. in grain.

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Summary

Root exudates were obtained from three mangrove species, viz. Bruguiera gymnorrhiza, Excoecaria agallocha, and Heritiera fomes. Spot tests revealed the presence of, presumably, phenolic compounds in the exudates. Paper chromatography revealed two spots each for B. gymnorrhiza and H. fomes and a single spot for E. agallocha. GC-MS analysis suggested the presence of aminopyrine, palmitic acid, stearic acid, di-n-propyl ether, and 2,5-anhydrogluconic acid in B. gymnorrhiza exudates, aminopyrine and palmitic acid in E. agallocha exudates, and aminopyrine, palmitic acid, and 2,5-anhydrogluconic acid in H. fomes exudates.

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Abstract  

The effect of sampling conditions on the decomposition of electrolytic manganese dioxide using thermal methods is reported. Significant differences were observed in the mechanism of the decomposition by simply changing the reaction environment from a closed pan to an open pan configuration. The purge gas atmosphere was also observed to influence the decomposition mechanism. As a product of the decomposition is oxygen, the change in the mechanism observed between the experimental conditions may be explained in terms of the ease of removal of oxygen from the reaction site.

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