We describe the polarity of selectivity of a GC separation system in terms of Retention Index data. In a series-coupled capillary system having stationary phases of differing polarity even slight (independent!) carrier gas flow changes in one part of the capillary series result in a dramatic change of selectivity. "Dramatic" is a relative term! Using a simple electronically controlled flow changing device we found retention index changes of several hundred units for polar test compounds such as phenols on a SESOKarbowax tandem. This means: The classical theoretical model for understanding retention (and selectivity) in chromatography must be corrected. We propose a very simple approach involving addition of the expression RESIDENCE TIME to the chromatographic vocabulary. Instead of using flow resistors, one can just add a pressure regulator to the coupling point. A powerful analytical concept is now in easy reach.

No abstract

No abstract

The soil albedo is mainly determined by soil mass constituents stable over a long time, such as organic carbon, carbonates and iron oxides, and is dynamically modified by the roughness and moisture of soil surfaces. Taking into account annual variations in the bare soil area of arable land in Poland extracted from Landsat 8 images, the amount of shortwave radiation reflected from the territory of Poland throughout the year only as an effect of smoothing arable soils previously treated by a plow and a pulverizing harrow was determined. The authors used the equations that predicted the half-diurnal albedo pattern of bare dry soil depending on the contents of soil organic carbon and sand fraction as well as quantitative indices of soil surface roughness.

No abstract