Exchange-correlation vector potentials and vorticity-dependent exchange-correlation energy densities in two-dimensional systems

We present a new approach how to calculate the scalar exchange-correlation potentials and the vector exchange-correlation potentials from current-carrying ground states of two-dimensional quantum dots. From these exchange-correlation potentials we derive exchange-correlation energy densities and examine their vorticity (or current) dependence. Compared with parameterizations of current-induced effects in literature we find an increased significance of corrections due to paramagnetic current densities.Comment: 5 figures, submitted to PR

Surfactant Residues in Maryland Tobacco Treated with a Fatty-Alcohol-Type Sucker-Control Formulation

AbstractSurfactant residues (Tween 80 Esters and Tween 80 free Polyols) were determined in Maryland tobacco treated with a fatty-alcohol-type sucker-control formulation. The levels of residues in leaves decreased throughout the growing and air-curing periods, but decreased the most during the first 24 hours after treatment. Factors affecting Tween 80 residue levels included dosage and location of leaves on the plant.</jats:p

''Ripening'' Tobacco with the Ethylene-Releasing Agent 2-Chloroethylphosphonic Acid

AbstractTreatment of flue-cured tobacco with the ethylene releasing agent 2-chloroethylphosphonic acid (CEPA) caused mature leaves to lose their green colour and turn yellow. The treated leaves appeared to go through a partial "yellowing'' or "colouring" phase prior to harvest. Treated leaves at harvest contained greater amounts of reducing sugars and lower levels of starch, relative to comparable untreated leaves. At the end of the curing process, comparisons between treated and untreated leaf showed that only small differences existed in total nitrogen, total alkaloids, starch, and reducing sugars. Statistically, protein of leaf treated with CEPA was significantly lower as compared to untreated leaf. For all yellowing times, dollar values per hundred weight of cured leaf from treated plants were higher than from untreated plants, but the average weight per leaf from treated plants was lower. During the curing process, leaf treated with CEPA can probably be subjected to shorter periods of yellowing or colouring than untreated leaf. If further work with "ripening'' chemicals such as CEPA show that they can be used to hasten yellowing or ripen tobacco successfully, as well as to reduce the time required for curing the crop, economic advantages are likely to accrue. It is to be hoped that such chemicals may help reduce the labour and investment required for crop production, and at the same time improve crop quality</jats:p