an experiment was carried out to evaluate and compare the effects of organic and inorganic selenium (se) sources on broiler male birds (ross 308). uniform broiler male chicks divided in to five groups with six replicates were fed with either normal feed (without supplemental se, negative control), 0.25 ppm of inorganic se, 0.5 ppm of inorganic se, 0.25 ppm of inorganic se + 0.25 ppm of organic ...

a risk assessment study was conducted to predict the expected hazardous influence on the ecosystem resulted from urbanization and industrialization activities at helwan area, egypt. to achieve these goals, soils, plants and water samples were collected from helwan area, and their total concentrations of inorganic contaminants (cd, cr, co, cu, fe, mn, ni, pb, and zn) and organic pollutants; such...

There are more H atoms than any other type of atom in an X-ray crystal structure of a protein-ligand complex, but as H atoms only have one electron they diffract X-rays weakly and are `hard to see'. The positions of many H atoms can be inferred by our chemical knowledge, and such H atoms can be added with confidence in `riding positions'. For some chemical groups, however, there is more ambigui...

The nitrogen cycle (N-cycle) in the biosphere, mainly driven by prokaryotes, involves different reductive or oxidative reactions used either for assimilatory purposes or in respiratory processes for energy conservation. As the N-cycle has important agricultural and environmental implications, bacterial nitrogen metabolism has become a major research topic in recent years. Archaea are able to pe...

Long hikes, for which my father took us, made me appreciate the wonderful nature that surrounded us in southern Germany. Nocturnal stargazing walks, together with popular science books that my aunt supplied, started my excitement for particle physics and the origin of the universe, a fashionable topic at the time. Unfortunately, our high school in Bad Windsheim did not offer a physics A-level c...

In the first and second of these works, Galen thoroughly refutes the statements of his predecessor, Erasistratus, point by point, and firmly establishes his own views on the importance of venesection. We are reminded here of the uncompromising thoroughness of Sir William Harvey in De Moto Cordis (1628). Galen, however, lacks Harvey's characteristic ability to incorporate simple yet decisive exp...

The elucidation of the detailed chemical mechanisms involved in biological, and particularly in enzymatic, processes has received considerable attention in recent years. Increasingly, the theories and methods of physical organic chemistry are being applied to this problem. Kosower has attempted to review the advances made in this field, as well as to suggest areas of biochemistry which should p...

has perpetuated the excellent publishing record of the past in this most recent edition. I am happy to state the affirmative. Since the previous edition was published in 1953, there was a tremendous amount of updating necessary, especially in terminology. This has been done quite well. A new chapter has been added on topographic anatomy and each section has been extensively revised or rewritten...

Genetic analysis indicates that Escherichia coli possesses two independent pathways for oxidation of phosphite (Pt) to phosphate. One pathway depends on the 14-gene phn operon, which encodes the enzyme C-P lyase. The other pathway depends on the phoA locus, which encodes bacterial alkaline phosphatase (BAP). Transposon mutagenesis studies strongly suggest that BAP is the only enzyme involved in...