Other Isotopes

Studies of biodegradation have made only limited use of metal isotopes  

Use of Mossbauer spectra generally requires the addition of Fe to the growth medium. This procedure has received extensive application to studying the environment of Fe in enzymes, and illustrative examples include the following  

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Over the next few years, both the mid-infrared and the far-infrared spectra for Ar-HF and Ar-HCl were extended to numerous other bands and to other isotopic species (most importantly those containing deuterium). In 1992, Hutson [18, 39] combined all the available spectroscopic data to produce definitive potential energy surfaces that included both the angle dependence and the dependence on the HF/HCl monomer vibrational quantum number v... 

Common irons is a mixture of four isotopes. Ten other isotopes are known to exist. 

Naturally selenium contains six stable isotopes. Fifteen other isotopes have been characterized. The element is a member of the sulfur family and resembles sulfur both in its various forms and in its compounds. 

Other isotopes are designated by mass numbers B (boron-10). 

Other isotopes can be used to determine the age of samples. The age of rocks, for example, has been determined from the ratio of the number of radioactive atoms to the number of stable gfPb atoms produced by radioactive decay. For rocks that do not contain uranium, dating is accomplished by comparing the ratio of radioactive fgK to the stable fgAr. Another example is the dating of sediments collected from lakes by measuring the amount of g Pb present. 

Naturally occurring isotopes of any element are present in unequal amounts. For example, chlorine exists in two isotopic forms, one with 17 protons and 18 neutrons ( Cl) and the other with 17 protons and 20 neutrons ( Cl). The isotopes are not radioactive, and they occur, respectively, in a ratio of nearly 3 1. In a mass spectrum, any compound containing one chlorine atom will have two different molecular masses (m/z values). For example, methyl chloride (CH3CI) has masses of 15 (for the CH3) plus 35 (total = 50) for one isotope of chlorine and 15 plus 37 (total = 52) for the other isotope. Since the isotopes occur in the ratio of 3 1, molecular ions of methyl chloride will show two molecular-mass peaks at m/z values of 50 and 52, with the heights of the peaks in the ratio of 3 1 (Figure 46.4). 

Tables 2,3, and 4 outline many of the physical and thermodynamic properties ofpara- and normal hydrogen in the sohd, hquid, and gaseous states, respectively. Extensive tabulations of all the thermodynamic and transport properties hsted in these tables from the triple point to 3000 K and at 0.01—100 MPa (1—14,500 psi) are available (5,39). Additional properties, including accommodation coefficients, thermal diffusivity, virial coefficients, index of refraction, Joule-Thorns on coefficients, Prandti numbers, vapor pressures, infrared absorption, and heat transfer and thermal transpiration parameters are also available (5,40). Thermodynamic properties for hydrogen at 300—20,000 K and 10 Pa to 10.4 MPa (lO " -103 atm) (41) and transport properties at 1,000—30,000 K and 0.1—3.0 MPa (1—30 atm) (42) have been compiled. Enthalpy—entropy tabulations for hydrogen over the range 3—100,000 K and 0.001—101.3 MPa (0.01—1000 atm) have been made (43). Many physical properties for the other isotopes of hydrogen (deuterium and tritium) have also been compiled (44).

Among other isotopes produced at SRP were uranium-233 for breeder research, cobalt-60 [10198-40-0] for irradiators, plutonium-238 for spacecraft such as V ojager 2in.d lunar research power suppHes, and califomium-252 as a fast neutron source. The accomplishments of Du Pont at SRP are well chronicled (53). 

The principal ha2ards of plutonium ate those posed by its radioactivity, nuclear critical potential, and chemical reactivity ia the metallic state. Pu is primarily an a-emitter. Thus, protection of a worker from its radiation is simple and usually no shielding is requited unless very large (kilogram) quantities are handled or unless other isotopes are present. 

Positron Imaging. Creating images of distributions of positron emitters requires a somewhat different type of apparatus. Positron cameras use many of the same technologies as do cameras for other isotopes, but there is a broader array of methods and physical arrangements. AH of these systems take advantage of the physical characteristics of positrons. 

The retention of radionuclides within the containment was little accounted for by the RSS, but ranges from little to very substantial because of agglomeration and deposition. This leads to a large over prediction of the iodine risk, but substantial agreement with RSS for some other isotopes. 

Its terrestrial abundance has been estimated as 2x10" ppm, which corresponds to a total of only 15g in the top 1km of the earth s crust. Other isotopes have since been produced by nuclear reactions but all have shorter half-lives than Fr, which decays by energetic emission, t j2 21.8 min. Because of this intense radioactivity it is only possible to work with tracer amounts of the element. 

Radium occurs only in association with uranium (Chapter 31) the observed ratio Ra/U is 1 mg per 3 kg, leading to a terrestrial abundance for Ra of 10 ppm. As uranium ores normally contain only a few hundred ppm of U, it follows that about 10 tonnes of ore must be processed for 1 mg Ra. The total amount of Ra available worldwide is of the order of a few kilograms, but its use in cancer therapy has been superseded by the use of other isotopes, and the... 

Silicon consists predominantly of Si (92.23%) together with 4.67% Si and 3.10% Si. No other isotopes are stable. The Si isotope (like the proton) has a nuclear spin I =, and is being increasingly used in nmr spectroscopy. Si,... 

Naturally occurring silver (Ag) consists of two isotopes. One of the isotopes has a mass of 106.90509 amu and 51.84% abundance. What is the atomic mass of the other isotope ... 

Radioactivity The ability possessed by some natural and synthetic isotopes to undergo nuclear transformation to other isotopes, 513 applications, 516-518 biological effects, 528-529 bombardment reactions, 514-516 diagnostic uses, 516t discovery of, 517 modes of decay, 513-514 nuclear stability and, 29-30 rate of decay, 518-520,531q Radium, 521-522 Radon, 528 Ramsay, William, 190 Random polymer 613-614 Randomness factor, 452-453 Raoult s law A relation between the vapor pressure (P) of a component of a solution and that of the pure component (P°) at the same temperature P — XP°, where X is the mole fraction, 268... 

Five other isotope studies of Maya skeletal populations in Belize are available for comparison with Cuello (Table 2.4 Fig. 2.3). These include a time series from Preclassic to Historic at Lamanai (White and Schwarcz 1989), an Early through Terminal Classic sequence at Pacbitun (White et al. 1993),... 

Some aspects of the biochemistry of metabolic processes affecting nutrients appear to have significant consequences for the expected behavior of stable carbon isotopes as tracers of diet. Specifically, we have seen that the simple model of a total scrambling of carbon atoms during endogenous biosynthesis is inconsistent with the expected pathways of some nutrients, whereas other isotopic records in ancient human tissues can be adequately accounted for by this model. 

Fe which have full width 2r at 0.2 mm s . Other isotopes are less demanding, e.g., Au, for which the lines are ten times wider. Most spectrometers are equipped with electromechanical Mossbauer velocity transducers of the loudspeaker type. This technique is suitable for velocity variations ranging from less than 1 mm s full scale up to several cm s and covers the whole reach of hyperfine splitting for most of the common isotopes. Kalvius, Kankeleit, Cranshaw, and others [1-5] have been pioneers in the field, who laid foundations for the development of high-precision drives with feedback amplifiers for proper linear velocity scales with high stability and low hum. Other techniques for Doppler modulation have been developed for isotopes with extremely narrow hyperfine lines, e.g., Zn. For such isotopes, piezoelectric transducers are mostly used [6, 7], more details of which are found in Sect. 7.2.1. 

The calibration procedure is sufficiently accurate for Doppler velocities in the regime 0 to 10 mm s beyond this range, laser calibration is more suitable. Calibration with ot-iron, as described, can also be used for Mossbauer measurements with other isotopes, e.g., Ni, Au, and Ir, for which suitable standard absorbers are not available (provided that the Doppler velocity range of interest is not significantly greater than 10 mm s ). This, of course, requires that the spectrometer is temporarily equipped with a Co source and an a-iron absorber. 

Mossbauer spectra of Dy, Sb, and other isotopes may show resonances at... 

For a comparison of experimental Mossbauer isomer shifts, the values have to be referenced to a common standard. According to (4.23), the results of a measurement depend on the type of source material, for example, Co diffused into rhodium, palladium, platinum, or other metals. For Fe Mossbauer spectroscopy, the spectrometer is usually calibrated by using the known absorption spectrum of metallic iron (a-phase). Therefore, Fe isomer shifts are commonly reported relative to the centroid of the magnetically split spectrum of a-iron (Sect. 3.1.3). Conversion factors for sodium nitroprusside dihydrate, Na2[Fe(CN)5N0]-2H20, or sodium ferrocyanide, Na4[Fe(CN)]6, which have also been used as reference materials, are found in Table 3.1. Reference materials for other isotopes are given in Table 1.3 of [18] in Chap. 1. 

Bohrson WA, Reid MR (1998) Genesis of evolved ocean island magmas by deep- and shallow-level basement recychng, Socorro Island, Mexico Constraints from Th and other isotope signatures. J Petrol 39 995-1008... 

As a noble gas, Rn in groundwater does not react with host aquifer surfaces and is present as uncharged single atoms. The radionuclide Rn typically has the highest activities in groundwater (Fig. 1). Krishnaswami et al. (1982) argued that Rn and all of the other isotopes produced by a decay are supplied at similar rates by recoil, so that the differences in concentrations are related to the more reactive nature of the other nuclides. Therefore, the concentration of Rn could be used to calculate the recoil rate for all U-series nuclides produced by a recoil. The only output of Rn is by decay, and with a 3.8 day half-life it is expected to readily reach steady state concentrations at each location. Each measured activity (i.e., the decay or removal rate) can therefore be equated with the input rate. In this case, the fraction released, or emanation efficiency, can be calculated from the bulk rock Ra activity per unit mass ... 

Mass spectrometric measurements on corals typically result in errors in and °Th of 2 per mil or better (2a), with the exception that fractional error in °Th typically increases progressively from this value for samples progressively younger than several ka. This results from the low concentrations of °Th in very young corals. Errors in Pa are typically somewhat larger than those of the other isotopes, with errors of several per mil, except for corals younger than a few ka. 

Am from its parent 241Pu and the other isotopes present can be effected by precipitation, ion exchange, or solvent extraction. 

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