Additivity, isotopic

For the case of only the isotope (A) in the sample and 6 is an additional isotope, all terms (B) disappear from equation (2). 

This has attracted considerable attention in evaluating the effectiveness of remediation either by natural populations or those enriched by specific additions. Isotopic analysis of the contaminant supplemented with that of established metabolites makes it possible to determine whether degradation... 

Iodine-131 was among the first radioactive isotopes used for radioimmunoconjugate preparation (Order, 1982 Regoeczi, 1984). Since the earliest studies on the efficacy of radiotherapy, additional isotopes have been employed, such as iodine-125, bismuth-212, yttrium-90, yttrium-88, technetium-99 m, copper-67, rhenium-188, rhenium-186, galium-66, galium-67, indium-111, indium-114 m, indium-115, and boron-10. 

In recent years additional informations on sulfur isotope fractionation mechanisms have been obtained from the analysis of the additional isotopes and (Farqnhar et al. 2003 Johnston et al. 2005 Ono et al. 2006, 2007). For long it was thonght and valnes carry no additional information, because sulfur isotope fractionations follow strictly mass-dependent fractionation laws. By studying all snlfnr isotopes with very high precision these authors could demonstrate that bacterial snlfate redaction follows a mass-dependent relationship that is slightly different from that expected by equilibrium fractionations. On plots vs mix-... 

The second double spike includes an artificially enriched isotope that does not exist in natural samples or in the first double spike. For example, b in the Pb- Pb double spike does not exist in natural samples or in the first Pb- Pb double spike. Therefore, the second double spike has an additional isotope ratio w. 

If sulfur or silicon, is present, the M + 2 will be more intense. In the case of a single sulfur atom, 34S contributes approximately 4.40% to the M + 2 peak for a single silicon in the molecule, 30Si contributes about 3.35% to the M + 2 peak (see Section 2.10.15). The effect of several bromine and chlorine atoms is described in Section 2.10.16. Note the appearance of additional isotope peaks in the case of multiple bromine and chlorine atoms. Obviously the mass spectrum should be routinely scanned for the relative intensities of the M + 2, M + 4, and higher isotope peaks, and the relative intensities should be carefully measured. Note that F and I are monoisotopic. 

SRM 979), Ni (nickel metal isotopic standard NIST SRM 986), Rb (rubidium chloride isotopic standard NIST SRM 984) and Sr (strontium carbonate isotopic standard NIST SRM 987). In addition, isotope reference materials are available for heavy elements such as T1 (thallium metal isotopic standard NIST SRM 997), Pb (NIST lead standard reference materials SRM 981-983) or U (uranium oxide NIST isotope standard U 005, U020, U350, U500 or U930) and others. The most important isotope standard reference materials applied in inorganic mass spectrometry are summarized in the table in Appendix V.17... 

Spark source (SSMS) and thermal emission (TEMS) mass spectrometry are used to determine ppb to ppm quantities of elements in energy sources such as coal, fuel oil, and gasoline. Toxic metals—cadmium, mercury, lead, and zinc— may be determined by SSMS with an estimated precision of 5%, and metals which ionize thermally may be determined by TEMS with an estimated precision of 1% using the isotope dilution technique. An environmental study of the trace element balance from a coal-fired steam plant was done by SSMS using isotope dilution to determine the toxic metals and a general scan technique for 15 other elements using chemically determined iron as an internal standard. In addition, isotope dilution procedures for the analysis of lead in gasoline and uranium in coal and fly ash by TEMS are presented. 

This research effort has demonstrated the capability of spark source and thermal emission mass spectrometry for determining the fate of trace elements in coal-fired, central power plants. Additionally, isotope dilu-... 

Because of the wide range of densities of interest, an additional isotope source was needed... 

The 7 Lu target is unique because this material has an extremely low natural isotopic abundance (2.61Z). A sample of several tens of milligrams of LU2O3 was obtained from J he Oak Ridge National Laboratory and had an isotopic enrichment of 70Z in i/8Lu. An additional isotope separation step was done on this sample at LLNL By this procedure we were able to make a target of isotopically pure 176Lu ( 99.9Z) that had a thickness of 22 mg/cm2 and which was supported on a Th substrate. This target was subsequently used for i80 Coulomb-excitation experiments. 

N, the N-labeled peptides exhibit additional isotope peaks in mass spectra. 

The photodissociation rate coefficients are included as source and sink terms in a system of time-dependent continuity equations for the atmosphere. Modem values for vertical (eddy) diffusion and solar photon flux are utilized. The system of 2nd-order ordinary differential equations is solved by integration, and yields chemical species abundances as a function of time and altitude. The isotope atmospheric chemistry includes only SO2 isotopologue photodissociation reactions and production of SO isotopologues. Additional isotopic reactions such as SO2 oxidation by OH, SO photolysis, SO disproportionation during self-reaction, and SO dimmer formation, have been neglected. My objective here is to focus only on SO2 photolysis as a S-MIF mechanism. 

Reflectivity data were collected for six different isotopic forms of the equimolar DPPC/oleic acid mixed monolayer using either hydrogenated oleic acid (h-OA) or perdeuterated oleic acid (d-OA) in conjunction with h-DPPC or d-DPPC. Additional isotopic variation was provided by using either ACMW or D2O as the subphase. Again, each monolayer was studied at three surface coverages of approximately 50, 60 and 70 A molecule. 

A Moon-forming collision of an approximately Mars-sized body with Earth (Hartmann and Davis, 1975 Cameron and Ward, 1976) would clearly result in catastrophic loss of volatiles from the pre-existing atmosphere and may have caused substantial loss of deep-Earth noble gases as well. Ahrens (1990, 1993) argued that virtually complete expulsion might have occurred by direct ejection from the impacted hemisphere and by shock-induced outward ramming of the antipodal planetary surface. However, losses may have been incomplete, and this event could have been followed by additional, isotopically fractionating losses driven by thermal processes (see Section 4.12.5). 

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