N-serve

Ic now serves to label the states iu the same sense n serves to label states for a square well. 

In some gas lasers it is preferable to use a mixture of the lasing gas M and a second gas N, where N serves only to be excited to N by collisions with electrons and to transfer this energy to M by further collisions ... 

Chloro 6-trichloromethyl pyridine (N-Serve ) Chromates, certain insoluble forms Chromic acid and chromates (as Cr)... 

Unknown amounts of these formulations and Amiben, Carbaryl, Chlordane, Cythion, Heptachlor, Maneb, Pyrethrum, Toxaphene and Zineb were deposited prior to the commencement of record keeping beginning June 1977. In addition to the listed pesticides 2619 g of Citcop, NAA, N-Serve, Dipel, Omite and Metasytox were deposited but not analyzed. 

Equation 6 allows the number of fringes to be converted to standard concentration units. The concentration values in fringes must be corrected for radial dilution. The number of data points n serves to divide the profile into zones. Each zone, AC = C — Cj i, is multiplied by x fx, where X = (xi + 1)/2 and each x is the distance down the fringe pattern... 

One of the nitrification inhibitors that has received attention in the United States is 2-chloro-6-(trichloromethyl) pyridine which is promoted under the name N-Serve. The minimum concentration of N-Serve in the soil for delaying nitrification at least 6 weeks is said to range from 0.5 to 10 ppm. 

The N-serve literature points out that a nitrification inhibitor is helpful only when conditions favor high nitrogen loss from the soil. Such conditions are heavy rainfall or heavy irrigation, coarse-textured soil, and soil in the pH range where nitrification readily occurs. Nitrate thus formed will leach down into anaerobic soil layers. 

SYNS DOWCO-163 NITRAPYRIN (ACGIH) N-SERVE NITROGEN STABILIZER... 

The simple nutrient measurement approach can be modified by the use of specific inhibitors. Chemicals that specifically inhibit either NH4+ oxidation (e.g., acetylene, aUylthiourea, methyl fluoride, N-serve) or N02 oxidation (chlorate) are added to rephcate incubation bottles (Bianchi et al., 1997 Bihen, 1976). The bottles must be incubated in the dark to prevent assimilation of by phytoplankton. A decrease in the concentration of N02 over time in the bottles in which NH4 oxidation was inhibited provides an estimate of the N02 oxidation rate. The rate of N02 increase in the botdes to which N02 -oxidation inhibitor was added approximates the rate of NH4+ oxidation. Aside from the overall hmitations of... 

To complicate matters further, N-serve is not soluble in water, so its addition to samples requires that it be dissolved in an organic solvent. This solvent can affect the other members of the community e.g., ethanol stimulates dark CO2 incorporation by heterotrophic bacteria (Owens, 1986 Ward, 1986). Thus in systems where heterotrophs are a large part of the overaU assemblage, the N-serve plus solvent approach may over estimate the dark CO2 incorporation due to nitrifiers (Priscu and Downes, 1985 Viner, 1990 Ward, 1986). 

Using the N-serve inhibition method with uptake to estimate nitrifica-... 

Because of the steep redox gradients in many sediments and the often rapid removal of the products of NTR by DNF and other dissimilatory processes, measurements of NTR remain problematic. NTR has been estimated in the presence and absence of specific inhibitors by the accumulation of NH4 (Henriksen et al., 1980 Caffrey et al., 2003) or by dark lT COj uptake into SOM (Dore and Karl, 1996). The inhibitors used include nitrapyrin (N-serve), methyl fluoride, dimethyl ether, acetylene, and aUylthiourea. Problems involved with these methods include nonspecificity of inhibitors and difficulty in determining the correct conversion factor for uptake to N1T4 oxidized, which has been observed to range from 8.3 to 42 mol N1T4 oxidized per mole fixed. Dore and Karl (1996) used an independent chemical assay of nitrite oxidation to verify the conversion factor used. NTR has also been estimated by the accumulation of nitrite in the presence versus absence of chlorate, an inhibitor of nitrite oxidation (Belser and Mays, 1980). NOa isotope dilution techniques, similar to those used to measure NMIN (see Section 5.2) have been used to measure NTR (Anderson et al., 1997 Risgaard-Petersen et al., 1994) however, when DNRA rates are high, the added NOa may disappear faster than it is sufficiently diluted to accurately estimate NTR. 

Nitrification is the process that converts NH4+ to N02 and then N03. There are four main methods for measuring nitrification—bioassays, incubation with C02 with N-serve inhibition, incubation with NH4+ or N02, and N isotope dilution (see method comparison by Enoksson, 1986). We offer a brief review here but direct the reader to Chapter 5 by Ward (this volume) for a more detailed discussion of the nitrification process and its measurement. 

One of the most sensitive ways to measure nitrification is to combine the inhibitor N-serve with incubation (Enoksson, 1986). This approach exploits the chemolithoautotrophic nature of nitrifiers whereby they incorporate " 002 while oxidizing N. Fixation of 002 is measured in the presence and absence of the N-serve (see Chapter 5 by Ward, this volume for nuances of N-serve use) with the difference being attributed to nitrifiers. To convert the 002 fixation rate to a nitrification rate requires the application of a conversion factor, which can be problematic (e.g., Glover, 1985). 

There have been very few comparisons of different methods for determination of nitrification rates. Enoksson (1986) compared three isotopic methods, incorporation with N-serve to inhibit nitrification, and N03 isotope dilution. She found ammonium oxidation measured with was 2-7 times greater than determined by the other methods, but pointed out that both different incubation times (from 1 to 12 days) and different substrate additions were used which would greatly alter the measured rates. Jones (1992) found a good relationship between a CO method and for measuring ammonium oxidation. Although most researchers have switched to direct assessment using there is stiU usage of the 002 method (e.g., Brion et al, 2000). 

Nucleobases can serve as either electron donors or electron acceptors in photo-induced electron transfer reactions with electronically excited acceptors (Ac) or donors (D), respectively. The free energy of photoinduced electron transfer reaction in which the nucleobase (N) serves as a donor or acceptor can be estimated using the Rehm-Weller equations (Eqs. 5 and 6), respectively. 

The N decay step completes the transport cycle even though the recovery of bacterio-rhodopsin has not yet taken place. Until this point in the photocycle, absorption of a second photon (e.g. by M in the blue-light effect ) defeats the transport process as it recovers bacteriorhodopsin without net proton translocation [137,138]. Absorption of a second photon by N, however, results in completion of the transport cycle and this takes place more rapidly than it does by the thermal route [139]. It appears then that the reactions after N serve simply to recover the chromophore. 

The highly electronegative elements F, O, and N serve as atomic hydrogen-acceptor sites. Hence HF, HOH, HOOH, ROH, RCOOH, H NH, R2NH and NCH are hydrogen acceptors. But so are aldehydes (ROCH), ketones (ROCR), ethers (ROR), esters (ROCOR), and tertiary amines (R3N), species which have no active hydrogens. 

Fig. 10. The various CNO cycles. The left part is the CN cycle where only C and N serve as catalysts for the conversion of four protons into 4He. Here the slowest fusion reaction is (p,7) reaction on 14N whereas the slower /3-decay has a half-life of 9.97m. In the CNO bi-cycle (right part), there is leakage from the CN cycle to the ON cycle through the branching at 15 N. The flow is returned to the CN cycle (which cycles 1000 times for each ON cycle) through lrO(p,a)14 N. The right bottom part represents additional cycles linking into the CNO cycle through the 170(p, y)18F reaction [13]...

The acute oral lDjq of nitrapyrin is 1072 mg/kg for rats. It is converted in the soil into 6-chloropicolinic acid, and it is essentially this that is taken up by the plants (Redemann et al., 1964). In the USA it has been introduced under the trade name N-Serve for the treatment of maize, cotton and wheat. 

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