Phosphorus influence

Calcium and phosphorus influence curd buffering properties and ripening characteristics. The calcium content in cheese may be determined by... 

C.A. English et al. Project PISA Phosphorus Influence on Steels Ageing -Analysis of Data from Work Packages 2, 4, 5, 6, 7 and 8, AMES report N20, Luxembourg, European Communities, 2008. 

C. English, S. Ortner, F. Gillemot, P. Kizler, M. Brumovsky, R. Langer, A. Ballesteros, P. Nenonen, F. Sevini, D. Bacon and S. Saillet. Phosphorus Influence on Steels Ageing (PISA), Final technical report Contract No FIKS-CT-2000-00080,2005, available at ftp //ftp.cordis.europa.eu/pub/fp5-euratom/docs/pisa projrep en.pdf (accessed March, 2014). 

Kost et al. have studied related reactions of 2-acyl-1-phenylpyrazolidines (422) and l-phenyl-2-thiocarbamoylpyrazolidines (423). The former are converted on reaction with phosphorus oxychloride into tetrahydropyrimido[l,2-a]indoles (424) (72CHE57) and the latter into tetrahydropyrimido[2,l-f ]benzothiazoles (425) under the influence of acidic agents (80CHE169). 

In all of the techniques which use artificial barriers to surface run-off of nutrients there is a need to consider the influence of land drains. If these are widespread in a catchment a reduction in nitrogen loading to the watercourses will be unlikely, because the nitrogen is predominantly dissolved and runs through the sub-soil to the drains. Phosphorus control by these barriers will be less affected by land drains because the main input of the phosphorus is in the particulate form which would be prevented from running off the surface to the watercourses. 

The above description of eutrophication has illustrated the complex nature of the problem, particularly in relation to the influence of nutrients, the multiplicity of sources of phosphorus and the spectrum of its bio-availability. Clearly, the most effective long-term solution to many of our eutrophication problems will be to reduce the nutrient load to affected waters. However, it has also been shown that, because the concentrations of available phosphorus required to impose a control on primary production is very low (e.g. 5-10/rgU total dissolved phosphorus), the reduction of nutrients from any one source alone is unlikely to be effective. 

Examination of the influence of agriculture on phosphorus input to freshwater requires careful study to determine the most appropriate control strategies. The influence will vary in relation to whether the phosphorus is dissolved or particulate. Also, we know that variation in the input of particulate and dissolved... 

In many of their complexes PF3 and PPI13 (for example) resemble CO (p. 926) and this at one time encouraged the belief that their bonding capabilities were influenced not only by the factors (p. 198) which affect the stability of the a P M interaction which uses the lone-pair of elecU"ons on p and a vacant orbital on M, but also by the possibility of synergic n back-donation from a nonbonding d , pair of electrons on the metal into a vacant 3d , orbital on P. It is, however, not clear to what extent, if any, the a and n bonds reinforce each other, and more recent descriptions are based on an MO approach which uses all (cr and n) orbitals of appropriate symmeU"y on both the phosphine and the metal-containing moiety. To the extent that a and n bonding effects on the stability of metal-phosphorus bonds can be isolated from each otlier and from steric factors (see below) the accepted sequence of effects is as follows ... 

Taking into account the high structural similarity of dppf and cdpp, their different influence on the reaction s selectivity has to be attributable to electronic effects. The electron density at the phosphorus atoms is significantly lower in the case of cdpp, due to the electron-withdrawing effect of the formal cobalt(III) central atom... 

Chromium, in fractional percentages, has a significant influence on corrosion rates. While it appears to be beneficial, some conflicting results have been reported and its contribution to the reduced corrosion of complex low-alloy steels containing copper and phosphorus is not large. 

A seminal paper [155] examined platinum-phosphorus NMR coupling constants in a series of cis- and trans-platinum(II and IV) complexes. The trans-influence had hitherto been explained in terms of d7r-p7r bonding, in other words, such a mechanism dominated with trans-effect... 

The influence of substituents in Ar1 is characterized by negative p values (plot based on ordinary Hammett a constants)208. Reactions involving other types of phosphorus nucleophiles (e.g. PPh2Alk)208 and ArS02 ions as nucleophiles have also been studied209. The work has been extended to the study of a-azidosulfones but the reaction does not turn out to be analogous210. There is base-catalyzed abstraction of hydrogen ion from the a-carbon atom. 

The characteristics are demonstrated in Fig. 10-21. As a result the elements influenced in this manner show various degrees of correlation. For element X, in terms of phosphorus ... 

Inorganic reactions in the soil interstitial waters also influence dissolved P concentrations. These reactions include the dissolution or precipitation of P-containing minerals or the adsorption and desorption of P onto and from mineral surfaces. As discussed above, the inorganic reactivity of phosphate is strongly dependent on pH. In alkaline systems, apatite solubility should limit groundwater phosphate whereas in acidic soils, aluminum phosphates should dominate. Adsorption of phosphate onto mineral surfaces, such as iron or aluminum oxyhydroxides and clays, is favored by low solution pH and may influence soil interstitial water concentrations. Phosphorus will be exchanged between organic materials, soil inter-... 

The land biota reservoir (3) represents the phosphorus contained within all living terrestrial organisms. The dominant contributors are forest ecosystems with aquatic systems contributing only a minor amount. Phosphorus contained in dead and decaying organic materials is not included in this reservoir. It is important to note that although society most directly influences and interacts with the P in lakes and rivers, these reservoirs contain little P relative to soil and land biota and are not included in this representation of the global cycle. 

Ingall, E. and Jahnke, R. (1997). Influence of water-column anoxia on the elemental fractionation of carbon and phosphorus during sediment diagenesis. Mar. Geol. 139, 219-229. 

The results reported in the previous sections illustrate the importance and versatility of P-centered radicals in organic chemistry. In this last section we would like to mention various reports that show that the presence of a phosphorus substituent close to a radical center can dramatically influence its properties. 

Studies on the formation and reactivity of P-centered radicals continue to be a versatile source of mechanistic information and reactions of interest in synthetic chemistry. Various new persistent or stable P-centered radicals have been described and could find applications as paramagnetic probes. The possibility of influencing the properties of organic free radicals bearing an appropriately located phosphorus group should find interesting applications. 

Conceptually and synthetically more straightforward molecules can be prepared through incorporation of chromophores onto simple phosphine moieties. The phosphorus fragment can be used either to influence or to organise the n-con-jugated systems. This section will focus only on derivatives tailored in order to exhibit specific properties related to applications in NLO,opto-electronics or as sensors. 

As already reported in Table 6, the solubility of phosphazene polymers is strongly influenced by the nature of the substituent groups attached at the phosphorus atoms along the -P=N- skeleton. Water-solubility, for instance, can be induced in polyphosphazenes by using strongly polar substituents (e.g. methylamine [84], glucosyl [495], glyceryl [496], polyoxyethylene mono-methylether [273] or sulfonic acid [497,498] derivatives), or may be promoted by acids or bases when basic (amino substituents like ethylamine [499]) or acid (e.g. aryloxy carboxylate [499] or aryloxy hydroxylate [295]) substituents are exploited. 

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