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  • Author or Editor: V. Medina x
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Measurements of Total Electron Content (TEC) were obtained from GPS and digisonde data, at Tucumán (26.69°S, 65.23°W), for days in different seasons, and with different geomagnetic activities, in 2004. Differences between both methods — associated with plasmaspheric content — are analyzed regarding hourly behavior, magnetic activity, and season; and are also compared with other latitude data. Results show a general good agreement between both methods, GPS measurements being generally higher around the diurnal maximum; results agree with theoretical predictions and findings from other authors as well.Maximum TECs occur in equinox, particularly, on magnetically perturbed days. Concerning the plasmaspheric content, our results do not show clear differences between quiet and perturbed days. The seasonal behavior can be associated with variations of the equatorial anomaly.

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The effect of three different modified atmospheres on the shelf-life of sponge cake was studied. Three packaging atmospheres were tested: 50% CO2: 50% N2, 100% CO2, and standard air as control. The samples were examined daily for visible mould growth and analysed periodically (after 2, 6, 13, 22 and 27 days) throughout storage (15–20 °C and 51–63% RH) for gaseous composition and microbial populations: mesophilic aerobic and anaerobic bacteria, lactic acid bacteria (LAB) and yeasts and moulds. The atmosphere CO2:N2 (50:50) extended the shelf-life of the sponge cakes by 2–3 days with respect to packaging in standard air.

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The effect of Azospirillum brasilense Sp7 (Sp7) on maize (Zea mays, Mill cv. B73) seedlings was compared when using two common carriers to deliver Sp7 to the seed: phosphate buffered saline (PBS) and magnesium sulfate (MgSO4). Seedling height, leaf chlorophyll levels, and root growth parameters were analyzed with WinRHIZO® at an early vegetative stage of plant development. Scanning and transmission electron microscope (SEM & TEM) analysis showed that carrier components do not effect bacterial binding to plant roots. MgSO4 + Sp7 caused a significant increase in the abundance of thick lateral roots, but stunted plant height, compared to other treatment groups, while relative chlorophyll contents (SPAD) significantly increased in seedlings inoculated with PBS + Sp7, revealing that the two inoculation carriers differentially affect the Sp7-associated plants.

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