Nitrogen partitioning

Urinary Nitrogen Partition and Amino Nitrogen Excretion. 202... 

B4. Barlow, A., and McCance, R. A., Nitrogen partition in newborn infants urine. Arch. Disease Childhood 23, 225-230 (1948). 

Hirose T. and Werger M. J. A. (1994) Photosynthetic capacity and nitrogen partitioning among species in the canopy of a herbaceous plant community. Oecologia 100, 203-212. 

Observations of enhanced Antarctic and mid-latitude ozone depletion following the eruption of Pinatubo confirm the impact of liquid aerosol surfaces on chlorine and nitrogen partitioning chemistry. Observations and laboratory studies have demonstrated the efficacy of heterogeneous... 

Inversely, the presence of ethanol and other alcohols in hydroalcoholic preparations may cause loss of solubility of hydrophilic peptides. In these products polypeptides with high hydrophobicity are preferred. The coefficient of ripartition 2-butanol/water (as nitrogen-partition coefficient) is used to estimate the lipophilic/hydrophilic balance of proteins for hydrophobic hydrolysates the nitrogen-partition coefficient value is 0.1-0.15 and lower for more hydrophilic derivatives (129). 

Daranlot J, Hincelin U, Bergeat A, Costes M, Loison JC, Wakelam V, Hickson KM (2012) Elemental nitrogen partitioning in dense interstellar clouds. In Proceedings of the National Academy of Science submitted, June 26, 2012 vol. 109 no. 26 10233-10238. doi 10.1073/ pnas.1200017109... 

Figure 3 Partitioning of losses of nitrogen fertilizer between denitrifieation and leaehing in 13 experiments. (Taken from Addiseott and Powlson, with permission of Cambridge University Press.)...

Consider a nucleus that can partition between two magnetically nonequivalent sites. Examples would be protons or carbon atoms involved in cis-trans isomerization, rotation about the carbon—nitrogen atom in amides, proton exchange between solute and solvent or between two conjugate acid-base pairs, or molecular complex formation. In the NMR context the nucleus is said to undergo chemical exchange between the sites. Chemical exchange is a relaxation mechanism, because it is a means by which the nucleus in one site (state) is enabled to leave that state. 

A solution of 1.0 mmol of 2-acetyl alkenoate in 2.5 mL of CH2C1, is added slowly to a solution of 4.0 mmol of titanium(IV) chloride in 7.5 mL of CH-CL under an atmosphere of nitrogen at — 78 °C. The mixture instantaneously turns deep red. and is stirred at — 78 °C before being quenched by the addition of 5 mL of sat. aq potassium carbonate. The mixture is then partitioned between 10 mL of bt20 and 10 mL of water. The aqueous phase is extracted with three 10-mL portions of Et2(), and the extracts are combined, washed with 10 mL of brine, and dried over anhyd potassium carbonate. Concentration under reduced pressure gives the crude product. Product analysis is by capillary GC. 

Fig. 12-2 Partitioning of the various forms of nitrogen in the atmosphere. Units are Tg N. (Reprinted with permission from R. Soderlund and T. Rosswall, The nitrogen cycles. In O. Huntizger (1982). "The Natural Environment and the Biogeochemical Cycles," p. 70, Springer-Verlag, Heidelberg.)...

Hence, the properties of the molecularly adsorbed N2 cancel as soon as we take kj Ki together, which is the relevant term in the formation of atomic nitrogen. Similarly, but on a much larger scale, partition functions cancel in the term hi Eqs. (51) and (52). Returning to Eq. (59), the factor of two arises because the rate describes the number of nitrogen atoms, whereas the transition state refers to the molecule, which dissociates into two atoms. 

U. Schenk, R. Manderschied, J. Hugen, and H.-J. Weigel, Effects of CO, enrichment and intraspecific competition on biomass partitioning, nitrogen content and microbial biomass carbon in soil of perennial ryegrass and white clover, J. Exp. Bot. 46 987 (1995). 

For multi-analyte and/or multi-matrix methods, it is not possible to validate a method for all combinations of analyte, concentration and type of sample matrix that may be encountered in subsequent use of the method. On the other hand, the standards EN1528 andEN 12393 consist of a range of old multi-residue methods. The working principles of these methods are accepted not only in Europe, but all over the world. Most often these methods are based on extractions with acetone, acetonitrile, ethyl acetate or n-hexane. Subsequent cleanup steps are based on solvent partition steps and size exclusion or adsorption chromatography on Florisil, silica gel or alumina. Each solvent and each cleanup step has been successfully applied to hundreds of pesticides and tested in countless method validation studies. The selectivity and sensitivity of GC combined with electron capture, nitrogen-phosphorus, flame photometric or mass spectrometric detectors for a large number of pesticides are acceptable. 

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