PS release

Formation of stable chelates with phytosiderophores occurs with Fe but also with Zn, Cu, Co, and Mn (Fig. 8) (39,207,208) and can mediate the extraction of considerable amounts of Zn, Mn, Cu, and even Cd in calcareous soils (204,209). There is increasing evidence that PS release in graminaceous plants is also stimulated in response to Zn deficiency (210-212), but possibly also under Mn and Cu deficiency (213). Similar to Fe deficiency, the tolerance of different graminaceous plant species to Zn deficiency was found to be related to the amount of released PS (211,212), but correlation within cultivars of the same species seems to be low (214). It is, however, still a matter of debate as to what extent PS release is a specific response to deficiencies of the various inicronutrients. Cries et al. (213) reported that exudation of PS in Fe-deficient barley was about 15-30 times greater than PS release in response to Zn, Mn, and Cu deficiency. In contrast, PS exudation in Zn-deficient bread wheat was in a similar range as PS... 

Polystyrene (PS) can contain some of its monomer, styrene, which is toxic (Group C - possible human carcinogen) and is the only source of toxicity of PS. PS is mainly used in construction in the form of high performance EPS foam, as insulation for floors, walls and roofs. PS foam, (known as Styropor, BASF) is mainly used for thermal insulation of buildings. For EPS, styrene monomer is used which is known to be toxic to the reproductive system, and hence residual monomer is a problem with the use of EPS as well. The burning of bulk or foam PS releases styrene as the hazardous chemical. 

Following the release of WASH-1400, the techniques were disseminated by the authors and interpreters through publications, lectures, and workshops. Many organizations set up in-housc PS. groups, and the nucleus of the organization that had produced the Reactor Safety Study coiKinucd at the NRC. 

Using a nomograph requires only the vessel volume in meters, selecting the dust class. St-1, St-2 or St-3 from Table 7-28. Using Tables 7-29 or 7-30 select the Kst value determined experimentally. The reduced pressure, Pred, (maximum pressure actually developed during a vented deflagration, termed reduced explosion pressure) must not exceed strength of vessel (see earlier discussion) and the Pstat, i.e., the vent device release pressure. Note that the static activation pressure, Ps[, must be determined from experimental tests of the manufacture of relief panels such as rupture disks. 

Calculated heat release distributions for total spark energy of 0.7mJ at 500 ps. (a) Ratio of capacity spark energy 20%. (b) Ratio of capacity spark energy 80%. 

Released ACh is broken down by membrane-bound acetylcholinesterase, often called the true or specific cholinesterase to distinguish it from butyrylcholinesterase, a pseudo-or non-specific plasma cholinesterase. It is an extremely efficient enzyme with one molecule capable of dealing with something like 10000 molecules of ACh each second, which means a short life and rapid turnover (100 ps) for each molecule of ACh. It seems that about 50% of the choline freed by the hydrolysis of ACh is taken back into the nerve. There is a wide range of anticholinesterases which can be used to prolong and potentiate the action of ACh. Some of these, such as physostigmine, which can cross the blood-brain barrier to produce central effects and neostigmine, which does not readily... 

In contrast to strategy 1 plants, grasses are characterized by a diffeient mechani.sm for Fe acquisition, with Fe-mobilizing root exudates as main feature. In response to Fe deficiency, graminaceous plants (strategy II plants) (39) are able to release considerable amounts of non-proteinaceous amino acids (Fig. 8B), so called phytosiderophores (PS), which are highly effective chelators for Felll (Fig. 8)... 

This release takes place predominantly in subapical root zones (30). Unlike Felll-citrate, Felll-PS chelates are stable even at high soil pH levels >... 

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