University of Jordan

About: University of Jordan is a education organization based out in Amman, Jordan. It is known for research contribution in the topics: Population & Medicine. The organization has 7796 authors who have published 13764 publications receiving 213526 citations.

Weed allelopathy, its ecological impacts and future prospects: a review

Abstract: Summary The importance, characteristics, positive and negative impacts, and future role of weeds as an integral part of the natural and agroecosystems are evaluated and discussed. Interference between plants in nature and the importance of differentiating between competition and allelopathy are interpreted. Allelopathy as one component of weed/crop interference, allelochemicals from weed species and their possible mechanism of action are listed and discussed. Weed species with inhibitory action against cultivated crops, other weed species, and plant pathogens, as well as self-inhibitory (autopathic) species are reviewed. Stimulatory or inhibitory allelopathic effects of different crop plants, trapping and catching species, and the potential of allelopathic weeds in inhibiting or stimulating certain parasitic weed species are discussed and evaluated. Allelopathy as a mechanism and future strategy for agricultural pest control and farm management and the potential use and development of some allelochemicals...

The Effect of Multiple Substituents on Sandwich and T-Shaped π–π Interactions

Abstract: Sandwich and T-shaped configurations of substituted benzene dimers were studied by second-order perturbation theory to determine how substituents tune pi-pi interactions. Remarkably, multiple substituents have an additive effect on the binding energy of sandwich dimers, except in some cases when substituents are aligned on top of each other. The energetics of substituted T-shaped configurations are more complex, but nevertheless a simple model that accounts for electrostatic and dispersion interactions (and direct contacts between substituents on one ring and hydrogen atoms on the other), provides a good match to the quantum mechanical results. These results provide insight into the manner by which substituents csan be utilized in supramolecular design.

Hypoglycemic Effects of the Volatile Oil of Nigella sativa Seeds

Abstract: The effects of the volatile oil extracted from Nigella sativa seeds on the levels of glucose and insulin were investigated in the rabbit. The i.p. administration of the volatile oil of N. sativa seeds (50 mg/ kg) to fasting normal and alloxan-diabetic rabbits produced significant hypoglycemic effects. These effects were consistent and time-dependent. In normal animals, 15% and 23% decreases in fasting plasma glucose levels were detected 4 h and 6 h, respectively, after treatment. The same treatment produced 12% and 21% decreases in the fasting glucose levels in diabetic rabbits at the 4 h and the 6 h time intervals, respectively. The administration of the volatile oil was not found to alter basal insulin levels in all animal groups, which might suggest a non-insulin-mediated mechanism of action for the demonstrated hypoglycemic activity. The mode of action of the hypoglycemic effects exhibited by the volatile oil extracted from N. sativa seeds remains to be elucidated.