Cesium concentration

Fig. 10. Effect of cesium concentration on ethylene glycol rates in 8-crown-6 ( ) and tetraglyme ( ) (92). Reaction conditions 75 ml solvent, 3 mmol Rh, cesium benzoate, 544 atm, Hj/CO = 1, 220°C, 4 hr.

Transport Model. A general release equation is developed by considering diffusion in both the liquid and gaseous phases. Figure 1 is a sketch of a vessel containing liquid sodium, blanketed by a flowing inert gas and maintained at constant temperature. The assumed cesium concentration profiles for both phases are shown in the sketch. Fick s law of diffusion may be applied to the liquid phase ... 

The flux of cations is governed by the following two relations. At high cesium concentrations (C > EID) (where E denotes the concentration of carrier in the membrane),... 

Calixarene crown-6 compounds, which are neutral extractants like crown ethers, are able to coextract technetium with cesium. Tests carried out with several calix-arene-crown ethers (MC7, MC8, MC14, BC2, BC5, BC8, and BC10) show that the extraction of technetium, present in the aqueous phase at a concentration 10 5 M, is enhanced as the cesium concentration in the aqueous phase increases from 10 5 to 10-2 M. As expected, an increase of nitrate concentration prevents pertechnetate extraction in competition with nitrate anion. The extraction of technetium is only appreciable when the nitric acid does not exceed 1 M. Distribution ratios DCs (close to 8) are comparable for the various calixarenes. However, a decrease of extraction is observed for naphtho derivatives.88 89... 

Olson, R.J. and Boggs, C.H. (1986). Apex predation by yellowfin tuna (Thunnus albacares) independent estimates horn gastric evacuation and stomach contents, bioenergetics and cesium concentrations. Canadian Journal of Fisheries and Aquatic Science 43,1760-1755. 

The cesium concentration of herbage ranges from 2 to 40 pg kg (or even wider), although very few data are available in this respect (Heine etal., 1977, Diehl and Schelenz, 1975). If the pH-value of the soil is low and there is a lack of potassium, cesium is better absorbed by the roots of the plants than in cases of high potassium content and high pH-values of the soils (Wiechen, 1972). 

Until now, there was no need to derive any limits for stable cesium concentrations in air, water, soil, plants, feeds or foods, based on the low concentration of the element in the biosphere and on its very low technical importance. 

A series of catalysts was prepared by the same procedure but the neutralisation of the mixture was carried out with a 6 M solution of CsOH until the pH of the mother liquors reached 9. A portion of the product obtained by filtration was then washed either once or twice with demineralized water to reduce the cesium concentration. 

Cesium concentration has a twofold effect. Firstly the conversion increases with the quantity of alkaline earth secondly, a selectivity optimum is obtained with 3 % w/w of cesium. With low weights of cesium dehydrohalogenation is the only side reaction giving a chemical balance of 100 %. 

An overview of measured radionuclide activities and selected element concentrations obtained in the youngest terminal shoot of the fir and spruce branches sampled from the Gorski Kotar area is presented in Table 10.8. Only rubidium and cesium concentrations in the tips of the fir branches were significantly higher than in the spruce tips. The concentrations of all the other elements studied, excluding zinc, iron, and lead, were nearly equal or insignificantly lower in the spruce than in the fir tips of the branches. 

Figure 58. Cesium-137 concentration in mule deer (Odocoileus hemionus) muscle and dietary cesium concentration curve generated for deer wintering on the middle winter range. From Alldredge et al. (1974).

Figure 3.19 XPS derived Cesium concentration in Silicon as a function of depth for 1 keV Cs" ion impact at 60° and 80° relative to the surface normal. The dashed line is to aid the eye. Reproduced with permission from van der Heide (2004) Copyright 2004 Elsevier.

In die case of Cs, this effect is relatively easy to examine as the enhance-ment/suppression induced scales with the concentration of Cs+ implanted into the substrate s surface. This is illustrated in Figure 3.29(a) for 1 keV Cs" " impact on Silicon and Figure 3.29(b) for Cs" " impact on Si02 with exponential trends noted between the Cesium concentration and the yield enhancement/suppression noted. 

Litvin et al. (1981a, 1982) have studied the systems MjO-NdjOj-PjOj-HjO (M = K, Cs), not using an open crucible but carrying out the experiments under partial vapor pressure of water. With low cesium concentrations the products are Nd(P03)3 and NdPjOj, depending on the temperature, and with higher cesium concentrations double polyphosphates are formed. The cubic cyclophosphate, CsNdP Oj2, is formed at 350-520°C, the monoclinic polyphosphate (P2j/n) CsNd(P03) at 520-675°C, and another monoclinic polyphosphate (P2,) above 675°C. 

The experimental conditions are shown in Table 1. All experiments used 6 dm of water, 200 g of sea sludge and 0.6 g of CsNOs. Cesium was so added as to produce concentrations of 0.3 mass% in sea sludge and 100 ppm in water. An employed experimental device is shown in Fig. 1. Two devices were prepared and 8 g of microorganisms activator was supplied to one of the two devices (scenario NA). The two devices were left undisturbed for 10 days and the cesium concentrations in water and sludge were measured by ion chromatography. Cesium in the sludge was dissolved by nitric acid prior to the measurement. 

Fig. 5. Cs+ distribution in the electrokinetic cell anode compartment (1), [BMIM][N(Tf)2] based liquid membrane (2) and cathode compartment (3). Initial cesium concentration 0.005 mol/L in anode chamber the solution equilibrated 24 hours at E=0 V then IV/cm gradient was applied...

---