Elevated emissions of sulfur dioxide, nitrogen oxides and ammonia in China have resulted in high levels of sulfur and nitrogen deposition, being contributors to soil acidification, especially in and near large cities. However, knowledge gaps still exist in the way that large cities shape spatial patterns of acid deposition. Here, we assessed the patterns of pH, sulfate, nitrate and ammonium in ...

Production of ammonia is difficult to find among the various studies of amino acid metabolism in protozoa. Several studies suggest that catabolism of arginine to ammonium is important for the growth of trichomonads. Trichomonads are amitochondriate zooflagellates that thrive under microaerophilic and anaerobic conditions. The authors were able to detect accumulation of ammonium ions and ammonia...

The strain of Escherichia coli K-12 with high aspartase activity was irradiated with UV. After mutagenesis and selection, the mutant B-715 was isolated which was 4-times more active in L-aspartic acid biosynthesis than parental K-12 strain. The highest productivity was achieved while the strain was cultivated in the ammonium fumarate medium in 37 degrees C for 18-30 hours. It was found that bet...

The stereoselective synthesis of penmacric acid, an optically active C-4 substituted pyroglutamic acid, has been efficiently achieved through an unusual 11-step sequence starting from simple N-triisopropylsilylpyrrole. The key-steps are the initial addition of the pyrrole nucleus onto a chiral nitrone and the obtention of the pyroglutamic acid moiety by reductive hydrogenation of the pyrrole fo...

That tryptophaln may be a precursor of nicotinic acid in rats and Neurospora was shown in the former by feeding experiments with niacine-deficient animals (13) and in the latter by studies with mutants requiring 3-hydroxyanthranilic acid (1), a metabolite known to arise from tryptophan. The mammalian experiments have been substantiated with isotopic experiments (8, 7) wvhere tryptophan-3-C14 an...

1. The effects of oral hydrochloric acid, ammonium chloride, sodium bicarbonate and ammonium bicarbonate on urea and ammonium excretion in rats on a constant diet were studied. 2. Hydrochloric acid acidosis significantly reduced urea excretion in the rat, with an equimolar increase in NH+4 excretion and no change in their sum. In ammonium chloride acidosis, most of the additional nitrogen intak...

Stachydrine (I), the methyl betaine of proline, occurs in a number of plants (1). Its biogenesis has been the subject of an investigation by Klein and Linser (2) who found an increase in stachydrine content of the planbs after an injection of proline into the hollow stems of Guleopsis ochroleuca and Stachys palustris. They suggest two schemes for the biogenesis of proline, one from ornithine, t...

This paper reports a study on nanocrystalline ceria powder prepared by high energy ball-milling and combustion synthesis methods. The combustion synthesis was carried out using ceric ammonium nitrate as oxidizer and citric acid, glycine or citric acid plus glycine as fuel. The minimum crystallite size of ceria powder is obtained by combustion synthesis of ceric ammonium nitrate and citric acid....