Hydrolysis of carboxylic esters p-nitrophenyl acetate (pNPA), p-nitrophenyl butyrate (pNPB) and p-nitrophenyl trimethyl acetate (pNPTA) was examined in oxovanadate solutions by means of (1)H and (51)V NMR spectroscopy. In the presence of a mixture of oxovanadates, the hydrolysis of carboxyester bonds in pNPA proceeds under physiological conditions (37 °C, pD = 7.4) with a rate constant of k(obs...

The catalytic properties of Al2O3-supported vanadia with a wide range of VOx surface density (1.4-34.2 V/nm) and structure were examined for the oxidative dehydrogenation of ethane and propane. UV-visible and Raman spectra showed that vanadia is dispersed predominately as isolated monovanadate species below ~2.3 V/nm. As surface densities increase, two-dimensional polyvanadates appear (2.3-7.0 ...

The calcium free sarcoplasmic reticulum calcium transport ATPase incorporates in the presence of magnesium ions approx. 8 nmol monovanadate per mg protein, indicating the formation of a complex containing one vanadate residue per enzyme molecule. On ligand-removal or dilution, the saturated enzyme complex displays biphasic decay kinetics, while the unsaturated complex slowly dissociates monopha...

Ammonium sulfate is one of the subsidiary components in the stealth liposome structure. The ratio of ammonium ion bound to liposome sphere to ammonium ions outside the liposome plays an important role in drug delivery formulation; accordingly, in order to quantify the ammonium ion in the liposome structure, a rapid and sensitive method was validated using a conductivity detector. Through this m...

background: surface water and groundwater pollution with various forms of nitrogen such as ammonium and nitrate ions is one of the main environmental risks. the major objectives of this study were to evaluate the capacity of natural zeolite (clinoptilolite) to remove no3- and nh4+ from polluted water under both batch and column conditions. methods: the laboratory batch and column experiments we...

to study the effect of type and different nitrogen fertilizers on controlling egyptian broomrape, field and greenhouse studies based on randomized complete block with three replications, were conducted at ferdowsi university of mashhad. greenhouse study treatments were consisted of ammonium nitrate, ammonium sulfate and urea each of which applied at four rates (75, 150, 300 and 350 kg/ha). fiel...

DNA microarray analysis of gene expression in steady-state chemostat cultures limited for potassium revealed a surprising connection between potassium and ammonium: potassium limits growth only when ammonium is the nitrogen source. Under potassium limitation, ammonium appears to be toxic for Saccharomyces cerevisiae. This ammonium toxicity, which appears to occur by leakage of ammonium through ...

nitrate and ammonium forms of nitrogen are being applied to improve plant growth and uptake of other nutrients. given that the effect of application of different nitrate to ammonium ratios accompanied by other fertilizers (i.e. fe, mn and zn) has not been studied on wheat growth as well as uptake of fe, mn and zn, three glasshouse pot studies were conducted with factorial arrangement of treatme...