Barium content

This assumption provides a convenient check on the calculation s accuracy, since we already know the fluid s barium content. 

In the analysis of the first sample, an attempt was made to obtain an almost entirely crystalline amalgam. This accounts for the high barium content in sample I, analysis I. 

Barium is relatively abundant in the earth s crust and is found in most soils at concentrations ranging from about 15 to 3,000 ppm (Bowen 1979 Schroeder 1970 Shacklette and Boerngen 1984). The barium content in cultivated and uncultivated soil samples collected during a number of field studies ranged from 15 to 1,000 ppm (mean concentration of 300 ppm) for B horizon soils (subsurface soils) in the eastern United States and from 70 to 5,000 ppm (mean concentration of 560 ppm) for B horizon soils in the western United States. Barium content ranged from 150 to 1,500 ppm for surface horizon soils collected in Colorado (mean concentration of 550 ppm) (Connor and Shacklette 1975). 

In a study of the barium content of the major human organs and tissues, the total body content of barium for a 70-kg adult male was estimated to be about 22,000 pg (ICRP 1974 Schroeder et al. 1972). Ninety-three percent of this barium was found in bone and connective tissue. Large amounts of the remaining 7% existed in fat, skin, and lungs (ICRP 1974 Schroeder et al. 1972). 

Chow TJ, Earl JL, Reed JH, et al. 1978. Barium content of marine sediments near drilling sites A potential pollutant indicator. Mar Pollut Bull 9 97- 99. 

Healy WB, Ludwig TG. 1968. Barium content of teeth, bone and kidney of twin sheep raised on pastures of differing barium content. Arch Oral Biol 13 559- 563. 

The substitution of lead by barium enhances the piezoelectric properties which peak when Pb/Ba I. At this and higher barium contents the structure changes to tetragonal with the polar axis parallel to the A-site tunnels. There is a morphotropic boundary, similar to that found in PZT compositions, and peak values of piezoelectric properties are found near the Pb1/2Ba1/2Nb206 composition. d33 rises to 220 pCN-1 and d31 rises to — 90pCN 1, while Qm increases to 300 and the Curie point falls to 250 °C thus most of the features peculiar to... 

Ba Zn based systems now have the majority market share for stabilisation of PVC-P in Europe due to extensive formulation development based on increasing the barium content and the important role of new and existing organic co-stabilisers (414). Suppliers include Akros. 

Lea D. W. and Boyle E. (1989) Barium content of benthic foraminifera controlled by bottom water composition. Nature 338, 751-753. 

Lea and Boyle (1989) showed that the barium content in foraminifera shells is, like cadmium, controlled by the barium content in bottom waters. Barium, in a broad sense, also cycles like a nutrient (depleted in surface waters, and higher in deep waters), but its regeneration occurs deeper than the organic matter. This results in a close correlation between barium and alkalinity in today s ocean (Lea, 1993). Like Cd/Ca, Ba/Ca in foraminifera has also been used, as a paleo-tracer of water masses (e.g.. Lea and Boyle (1990), but suffers the same carbonate-saturation-state-linked effect as Cd/Ca (McCorkle et al., 1995). 

Generally impurities in the oxidizers or other inorganic materials disturb the flame colour. Strontium salts usually contain some barium salt as an impurity which produces the undesirable spectrum BaCl or BaOH band and disturbs the colour of the flame. Accordingly it is necessary to use strontium salts of high purity to obtain a good red flame. Strontium and barium belong to the same group of elements, and it is difficult to separate barium and strontium salts industrially, but in a laboratory strontium salts can be purified until they have a barium content of less... 

Strontium determinations in soils, sea water, etc., have the same topicality as similar determinations in biological materials. The strontium and barium content of a number of soils and plants has been determined by Bowen and Dymond (5). They found that strontium was preferentially absorbed with respect to calcium by plants from most of the )ils considered while barium was taken up much less readily. 

A systematic study of the Eu/Yb and Eu/Ba alloys has been made [52, 53]. In the ytterbium system, the Curie temperature falls from 90 to 5 K and the saturation field also falls from 265 to 160 kG as the ytterbium content increases from 0 to 92 at. %. The relationships are linear apart from a discontinuity at 50 at. % where there is a phase change. Similarly for barium the Curie temperature falls from 90 to 40 K and the field from 265 to 206 kG as the barium content rises to 50 at. %. However, the chemical isomer shift is not significantly altered. The sign of the magnetic field is known to be negative from neutron diffraction data. Calculations suggest that a contribution of —340 kG to the field in europium metal arises from core polarisation, that +190 kG comes from conduction-electron polarisation by the atoms own 4/-electrons, and that —115 kG comes from conduction-electron polarisation, overlap, and covalency effects from neighbouring atoms. 

The barium content of Brazil nuts Ber-tholhtia excdsa) is very high (1.5-4 g kg ). 

The barium content of human tissues is dependent on age. For example, in adults the liver contained barium levels of 4-20 mg kg dry matter, whereas in children the typical liver barium content was much higher, at 144 mg kg The majority of tissue barium is accumulated in the skeleton, with typical adult levels ranging from 16 to 95 mg kg dry matter. Very high barium contents were also determined in the prostate gland of children, with up to 1.3gkg dry matter in infants (Jaritz 1998). Other sources have described lower levels of barium in human tissues however... 

The barium content of plants grown on Pleistocene sand or moor was found to be higher than those grown on weathering soils of shell limestone or on Holocene meadows (Jaritz 1998). There appears to be no clear relationship between the age of plants and barium content, however (Lasztity 1987, Jaritz 1998). 

For graphite-supported catalysts, the presence of barium decreased the number of copper and of chromium atoms at the surface. From the relative intensity of the XPS signals it could be seen that the dispersion of copper varied with the barium content. In comparison with the alumina supported catalysts the Cu content was more significant whereas it was the contrary with Cr species which disappeared completely after addition of barium. These results are in agreement with XRD characteristics showing the presence of a CUC1O2 phase on the surface of the catalyst precursor. 

Table 1. Strontium and barium contents of living bone.

The amount of strontium and barium in bones and teeth differs by two orders of magnitude (Table 1). Human strontium and barium levels in bones and teeth exist in a bimodal literature that derives from an interest in the incorporation of °Sr in the 1950s, and a more recent group of studies that focus on strontium s effect on mineralization. A wide range in strontium content in human bone is reported in groups of studies that are fifty years apart, but, in general, modem human bone and enamel tends to have strontium content <200 ppm, while barium content is commonly reported at less than 10 ppm. The amount of strontium in a normal human diet ranges from 0.023 to 0.046 mmol/Sr/day (Marie et al. 2001), and when administered with calcium, strontium is adsorbed to a lesser extent (Milsom et al. 1987). 

The effect of the content of alkali earth oxides MgO and BaO on the catalytic and basic properties of NaX zeolites have also been investigated by Kovacheva ct al. (32. 46]. For the MgO-modified NaX zeolites, the best catalytic properties were obtained by NaX zeolite impregnated with a maximum of 13 wt. % MgO. The significant improvement in the catalytic properties was attributed to the presence of a moderate amount of strong basic sites. The catalytic activity was found to depend on the temperature and the MgO content. It was demonstrated that the catalysts possess well preserved crystal structure and low amount of MgO crystal phase. It was reported that the amount of basic active sites but not the strength is dependent on the content of MgO in the zeolite. BaO/NaX was also found to be an effective catalyst for the oxidative methylation of toluene with methane. The catalytic properties of this zeolite was reported to be superior to those of the MgO/NaX zeolite. It was demonstrated that an increase in the barium content leads to an increase in the amount of basic sites and a corresponding increase in catalytic activity. The catalysts were found to possess a preserved crystal structure and the existence of differently dispersed BaO and formation of BaC03 were detected in the catalysts. The conversion of toluene, selectivity and the yield of ethylbenzene plus styrene were reported to depend on (i) the content of barium in the zeolite, (ii) the reaction temperature, (iii) the time of catalytic use, (v) the state of the zeolite crystal structure and (vi) the state of barium in the zeolite lattice. 

The results of the studies on the barium concentration of sea water have conversely, clearly demonstrated the existence of a variation in the barium/chlorinity ratio. Prior to 1966 very few analyses of the barium concentration of sea water had been reported. Turekian and Johnson (22) have recently reported the results of over 250 determinations of the barium concentration of sea water. The average values reported for the barium content of 24 samples from the Atlantic Ocean, the area which is of concern in the present investigation, range from 9 to 30 p.p.b. 

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