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  • Author or Editor: A. Ahmad x
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Thirty-day-old plants of Lens culinaris (L.) Medic. cv. Pusa-6 were sprayed with 10-10, 10-8 or 10-6 M aqueous solutions of 28-homobrassinolide (HBR). Root length and nodule number per plant decreased, whereas the leaf nitrate reductase activity (E.C. 1.6.6.1) at 60, 90 and 120 days after sowing and the seed yield at harvest increased significantly in plants sprayed with either concentration of HBR. The values increased at first with an increase in the concentration of HBR but decreased with a further increase above 10-8M, which proved best for improving seed production.

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The economic threshold level of Meloidogyne incognita, Alternaria dauci and Rhizoctonia solani were determined on carrot (Daucus carota L.) under greenhouse conditions. The results revealed that plant length, plant fresh weight, shoot and root dry weight, chlorophyll and carotenoid decreased progressively with the corresponding increase in the inoculum levels of each pathogen. The significant reduction in plant growth parameters, chlorophyll and carotenoid occurred when 2000 or more second stage juveniles (J2s) of M. incognita, 1.0 g or more inoculum of A. dauci or R. solani per kg soil were inoculated. Maximum reduction in plant growth attributes, chlorophyll and carotenoid occurred at the highest inoculum level of the test pathogens. Increase in the inoculum level of M. incognita caused an increase in the number of root galls, while the multiplication of nematode was found inversely related to the inoculum density. The increase in the inoculum levels of A. dauci and R. solani resulted in a progressive increase in leaf blight and crown rot indices and caused a higher reduction in plant growth parameters. The damaging threshold level of M. incognita was 2000 J2 per kg soil while 1.0 g per kg soil of A. dauci or R. solani was threshold level on carrot. The assessment of infestation levels of test pathogens will enable growers to cost-effectively select and implement the management tactics.

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Effects of Meloidogyne incognita, Alternaria dauci and Fusarium solani were studied on carrot (Daucus carota L.) growth, chlorophyll, carotenoid and proline contents in different types of soil. Plants grown in 20:80 and 40:60% sand:clay soil mixtures showed a significant increase in root dry weight, chlorophyll and carotenoid contents compared to plants grown in 100% clay soil. However, use of 60:40 sand:clay resulted in a similar root dry weight, chlorophyll and carotenoid contents as was found in carrots grown in 100% clay soil. Inoculation of plants with M. incognita, A. dauci or F. solani caused a significant reduction in root dry weight, chlorophyll and carotenoid contents in all soil types as compared to their respective control. Inoculation of plants by A. dauci caused the greatest reduction in root dry weight followed by F. solani and M. incognita in different sand and clay mixtures. Use of 20:80, 40:60 or 60:40 sand:clay mixtures caused a significant increase in proline content of plants over those grown in 100% clay soil. Similarly, inoculation of M. incognita, A. dauci and F. solani caused a significant increase in proline content in all soil types compared to their respective control.

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Authors: S. Ahmad, A. Mannan, I. Qureshi, S. Khan and I. Ahmad

Abstract  

A rapid and simple method for the determination of iodine from water has been described which is based on preconcentration of iodine with 0.1M solution of 4-(5-nonylpyridine) in benzene or carbon tetrachloride from 1–2M HNO3 followed by neutron irradiation and gamma-ray activity measurements. A clinical survey of endemic goitrous area has also been made to find a possible correlation between the endemic goiter and iodine deficiency in water.

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Rapeseed oil was used for frying of potato fillets (French fries) for 4 consecutive days at a rate of 20 minutes per day. The quality constants such as peroxide value (POV), anisidine value (AV), free fatty acid polar compounds (FFA%) and colour index (as OD at 420 nm) were determined before and after frying. The results showed an increasing pattern in the values of quality parameters. The POV increased from 4.42 to 17.00 meq kg-1, AV from 8.37 to 65.60, FFA from 0.02 to 1.90% and colour (absorbance at 420 nm) from 0.16 to 2.20. Fried rapeseed oil was mixed separately with 3 levels of MgO (2, 4 and 6% w/w) and activated charcoal (2, 6 and 10% w/w). For all the treatments the average % improvement of quality indices was statistically analysed. Increasing levels of both activated carbon and MgO significantly affected (P<0.05) the different quality parameters tested so far.

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Authors: Z. U. Ahmad, Mursaleen and Q. A. Khan
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Abstract  

A copper, zinc and aluminium mixed oxides sample having the nominal composition 0.25 CuO/0.03 ZnO/Al2O3 was prepared by impregnating Al(OH)3 with copper and zinc nitrate solutions, drying at 100 °C then heating in air at 600 °C. The obtained solid was exposed to different doses of -rays (20–160 Mrad). The surface characteristics namelyS BETVP andr of different treated adsorbents were determined from N2 adsorption isothems measured at –196 °C. The catalytic activity of various irradiated solids was determined by following up the kinetics of CO-oxidation by O2 at 150–200 °C. The results showed that the doses up to 80 Mrad resulted in no significant change in theS BET but increased slightly theV P (20%) of the treated adsorbents. The irradiation at 160 Mrad caused an increase of 20% in theS BET of the irradiated solid sample. The catalytic activity increased progressively by increasing the dose, a dose of 160 Mrad brought about an increase of 140% in the catalyst's activity. The apparent activation energy of the catalytic reaction decreased monotonically by increasing the absorbed dose of -rays which was attributed to a parallel induced decrease in the value of pre-exponential term of the Arrhenius equation. The observed increase in the catalytic activity due to -irradiation has been interpreted as a result of increasing the concentration of catalytically-active sites contributing in chemisorption and catalysis of CO-oxidation via a possible fragmentation of CuO crystallites.

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Summary

A simple, accurate, selective, precise, economical, and stability-indicating high-performance thin-layer chromatographic method for simultaneous analysis of mevastatin and pravastatin in fermentation broth has been established and validated. Compounds were separated on aluminium foil TLC plates precoated with silica gel 60F254; the mobile phase was toluene-ethyl acetate-formic acid 3:2:1 (v/v), which gave compact bands of mevastatin and pravastatin (RF 0.48 ± 0.02 and 0.31 ± 0.02, respectively). Detection at 237 nm resulted in r = 0.992 and 0.995 for mevastatin and r = 0.995 and 0.994 for pravastatin, for peak height and peak area, respectively. The limits of detection and quantification for mevastatin were 20.1 and 60.8 ng per band, and for pravastatin 19.2 and 58.3 ng per band, respectively. The method enabled effective quantification of mevastatin and pravastatin in the fermentation broth of Actinomadura macra and can therefore be used as a stability-indicating method for routine analysis of these compounds during bioconversion.

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Abstract  

Effects of humidity and light conditions /fluoroscent light, sunlight and diffuse sunlight/ on the response of 2 mm thick clear polymethylmethacrylate /PMMA/ dosimeter during irradiation and during postirradiation storage were determined spectrophotometrically at 305 and 314 nm. The results showed that irradiation of dosimeters at 12–97% relative humidity did not result in any change in the response upto 2 weeks of post-irradiation storage. However, there is some decrease in the response at higher humidities />76%/ for longer storage time. Post-irradiation storage and dosimeters at constant relative humidity conditions between 35 and 97% had no effect on the response up-to 3 weeks. Post-irradiation storage at lower relative humidity /12%/ showed some decrease in the response for longer periods. The response of dosimeter is not very sensitive to short time exposure to diffuse sunlight and fluorescent light. However, a significant increase in the optical density was observed during exposure of dosimeters to direct sunlight.

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