Stable isotopes may provide evidence for starvation in reptiles

Previous studies have attempted to correlate stable isotope signatures of tissues with the nutritional condition of birds, mammals, fishes, and invertebrates. Unfortunately, very little is known about the relationship between food limitation and the isotopic composition of reptiles. We examined the effects that starvation has on delta13C and delta15N signatures in the tissues (excreta, carcass, scales, and claws) of six, distantly related squamate reptiles (gaboon vipers, Bitis gabonica; ball pythons, Python regius; ratsnakes, Elaphe obsoleta; boa constrictors, Boa constrictor; western diamondback rattlesnakes, Crotalus atrox, and savannah monitor lizards, Varanus exanthematicus). Analyses revealed that the isotopic composition of reptile carcasses did not change significantly in response to bouts of starvation lasting up to 168 days. In contrast, the isotopic signatures of reptile excreta became significantly enriched in 15N and depleted in 13C during starvation. The isotopic signatures of reptile scales and lizard claws were less indicative of starvation time than those of excreta. We discuss the physiological mechanisms that might be responsible for the starvation-induced changes in 13C and 15N signatures in the excreta, and present a mixing model to describe the shift in excreted nitrogen source pools (i.e. from a labile source pool to a nonlabile source pool) that apparently occurs during starvation in these animals. The results of this study suggest that naturally occurring stable isotopes might ultimately have some utility for characterizing nitrogen and carbon stress among free-living reptiles.     

Stable isotopes and the international system of units

It is now over 60 years since Nier built the first isotope ratio mass spectrometer. The introduction of continuous-flow techniques heralded a huge expansion in the use of stable isotopes in biomedical and environmental sciences, yet there is no consensus on the appropriate units, especially in the biomedical field. Most isotope ratio mass spectrometry (IRMS) instruments calculate isotopic abundance in terms of delta notation (delta, per thousand, per mil), which is a convention determined by geochemistry, because most of the original IRMS instruments were developed in isotope geochemistry laboratories to measure natural abundance variations. Delta units are not SI units. This paper considers the appropriate units for studies using stable isotopes based on the International System of Units (SI). The SI base unit for concentration is the mol, from which atom fraction and mol fraction are derived. The units of stable isotope abundance, atom % and mol %, are the atom and mol fractions expressed as percentages. Atom % excess and mol % excess are the SI units of enrichment and are to be recommended for use in tracer studies.     

Application of mercury isotopes and their production

Mercury isotopes are now broadly applied in various fields of science and technology. They are used in medicine, nuclear physics investigations, RF standards, nuclear gyroscopes, mercury analysing devices etc. One of the most promising applications is the use of weakly enriched (up to 3%) isotope¹⁹⁶Hg in fluorescent lamps for enhancing their light efficiency. Besides, the application of²⁰¹Hg and²⁰²Hg as the target material for the production at low-energy cyclotrons of one of the most consumed²⁰¹Tl isotope in medicine seems to be perspective. Various methods were proposed and examined for the separation of mercury isotopes. There are: electromagnetic, photochemical, centrifugal, laser, photoionizing method etc. But only two of them were effective for the mercury isotope separation: electromagnetic and photochemical ones. This paper presents a review of the experimental results on separation of various mercury isotopes by different methods.     

Determination of heavy metals in sewage-based fertilizer using short-lived isotopes

A fully instrumental method for the neutron activation analysis of heavy metals in sewage sludges has been developed, based on short-lived isotopes, and restricting the total experiment time to 1 hour per sample. The irradiation scheme consists of a cyclic and conventional part, the period of the cyclic irradiation being optimised for the determination of lead, using^207mPb (T=0.8 s). Gamma ray spectra from Ge(Li) detectors are stored on magnetic tape and analysed using the SAMPO programme. An IDENTIFY subroutine enables absolute determinations to be made eliminating the need for standards. Sensitivities and detection limits for 21 heavy metals have been determined and the results for several sludges are presented.     

Enriched stable isotopes for 123I production: Pathways and prospects

Large-scale production of radioisotopes for medical application was impeded by limited capabilities of the electromagnetic separation. Nowadays the centrifuge separation process involves more than two dozens of chemical elements. The cost of isotopes is incomparably lower than of those produced by electromagnetic separation, which has made enriched isotopes more practicable and has extended their application scope. The development of new isotope targets has ensured the realization of more effective schemes of ¹²³I production. The processes of ¹²⁴Xe and ¹²³Te production are reviewed.     

Frontiers of heavy element nuclear and radiochemistry

The production and half-lives of the heaviest chemical elements, now known through Z=112, are reviewed. Recent experimental evidence for the stabilization of heavy element isotopes due to proximity to deformed nuclear shells at Z=108 andN=162 is compared with the theoretical predictions. The possible existence of isotopes of elements 107–110 with half-lives of seconds or longer, and production reactions and experimental techniques for increasing the overall yields of such isotopes in order to study both their nuclear and chemical properties are discussed. The present status of studies of the chemical properties of Rf, Ha, and Sg is briefly summarized and prospects for extending chemical studies beyond Sg are considered.     

Status of heavy element synthesis in RIKEN

A gas-filled recoil separator for heavy element research was installed at the experimental hall of RIKEN linear accelerator facility. An acceptance of the separator was measured using a-particles from ²⁴¹Am source. Measured acceptance was 12.2 msr. Transmissions of the separator were measured with low-energy Pb (0.26 AMeV) and Bi (0.11 AMeV) recoils. It was found that the transmission for Pb (0.26 AMeV) was 0.84, and that for Bi (0.11 AMeV) was 0.33. Equilibrium charge states for Pb and Bi in helium gas were deduced.     

Safety-catch linker strategies for the production of radiopharmaceuticals labeled with positron-emitting isotopes

A novel synthetic stratetegy for compounds labeled with the positron-emitting isotope carbon-11 is described. The use of precursors attached to a solid support via safety-catch linkers allows selective release of radiolabeled material, leaving unreacted precursor attached to the support. Two different linkers demonstrate the application to the preparation of radiolabeled N-alkyl tertiary amines and N-alkylsulfonamides. This technique is expected to lead to more widespread use of positron emission tomography for the in vivo analysis of compound behavior.     

RFNC-VNIIEF capabilities to production high pure isotopes for scientific and medical applications

This technical paper presents information on the basic equipment and more than thirty-year experience of RFNC-VNIIEF activities in the sphere of producing highly enriched isotopes of actinide elements - thorium, uranium, neptunium, plutonium, americium and curium - for scientific research and practical applications. Electromagnetic separator and radiochemical methods are used to produce super pure isotope samples for nuclear-physical radiometric and mass-spectrometric equipment, and also as tracers when analyzing environmental contamination. There are stated science and engineering elaborations of technologies aimed at producing alpha-ray radiating radionuclides - thorium-229, thorium-228, actinium-225, radium-224 - for the purpose of anti-cancer therapy using bismuth-212 and bismuth-213 produced by specially developed generators.     

Trace element analysis via heavy ion induced X-ray fluorescence

Ohne ZusammenfassungWork supported by the National Science Foundation, Grant MPS 75-17746.     

Stable carbon isotopes as an indicator for soil degradation in an alpine environment (Urseren Valley,Switzerland)

Analyses of soil organic carbon (SOC) content and stable carbon isotope signatures (δ¹³C) of soils were assessed for their suitability to detect early stage soil erosion. We investigated the soils in the alpine Urseren Valley (southern central Switzerland) which are highly impacted by soil erosion. Hill slope transects from uplands (cambisols) to adjacent wetlands (histosols and histic to mollic gleysols) differing in their intensity of visible soil erosion, and reference wetlands without erosion influence were sampled. Carbon isotopic signature and SOC content of soil depth profiles were determined. A close correlation of δ¹³C and carbon content (r > 0.80) is found for upland soils not affected by soil erosion, indicating that depth profiles of δ¹³C of these upland soils mainly reflect decomposition of SOC. Long‐term disturbance of an upland soil is indicated by decreasing correlation of δ¹³C and SOC (r ≤ 0.80) which goes in parallel with increasing (visible) damage at the site. Early stage soil erosion in hill slope transects from uplands to adjacent wetlands is documented as an intermediate δ¹³C value (?27.5‰) for affected wetland soil horizons (0–12 cm) between upland (aerobic metabolism, relatively heavier δ¹³C of ?26.6‰) and wetland isotopic signatures (anaerobic metabolism, relatively lighter δ¹³C of ?28.6‰). Carbon isotopic signature and SOC content are found to be sensitive indicators of short‐ and long‐term soil erosion processes. Copyright © 2009 John Wiley & Sons, Ltd.     

非传统稳定同位素在土壤重金属源解析方面的应用

随着工业发展,土壤中累积的重金属对人类产生健康威胁。在全面评估土壤重金属污染的情况下,通过非传统稳定同位素测量可以对其来源进行有效解析。鉴于这一新兴领域的快速发展,对非传统稳定同位素在土壤重金属源解析中的作用进行了阐述。在此基础上,提出了现有的问题和展望,为土壤重金属污染源解析理论、技术的研究与应用提供借鉴,推进土壤重金属污染防控的建立与完善。     

IAEA activities for the production and utilization of isotopes: Some examples of recent work

The paper gives a brief overview of typical IAEA activities which contribute to the production of isotopes in nuclear reactors and accelerators, as well as their use. The areas touched upon include (1) isotope production in research reactors and accelerators, (2) quality control and quality assurance in radioanalytical measurements, (3) neutron activation analysis, (4) nuclear methods for land mine detection, (5) radiopharmaceuticals and nuclear medicine, (6) isotope techniques of water resource management and (7) soil management and crop nutrition.     

Separation of heavy ion induced carrier free europium isotopes from bulk quantity of cesium

Theoretical calculation shows considerable cross section for production of^145,146Eu through¹³³Cs(¹⁶O,xn) nuclear reaction. To reduce the trials with costly particle accelerators beam time experimental simulation for separation of carrier free europium from cesium target matrix has been performed. Trace amounts of^152,154Eu have been separated from macro and trace amounts of cesium. A high separation factor has been achieved when 1% HDEHP and 10⁻³M HCl is used as organic and aqueous phase respectively. Trace europium has been successfully back extracted into HCl, ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) medium.     

A compilation of charged particle production cross-sections by 14 MeV neutrons for Nb and Mo isotopes

A compilation of the cross sections (n, p), (n, n′ p), (n, α) (n, n′ α) and (n,³He) for⁹³Nb,^{92,95,96,97,98,100}Mo by 14 MeV neutrons is presented in the form of a table containing the results of nearly 70 different measurements, mainly obtained by activation analysis. Brief assessments of the experimental methods and the data status are given.     

Industrial scale production of stable isotopes employing the technique of plasma separation

Calutrons, centrifuges, diffusion and distillation processes are some of the devices and techniques that have been employed to produce substantial quantities of enriched stable isotopes. Nevertheless, the availability of enriched isotopes in sufficient quantities for industrial applications remains very restricted. Industries such as those involved with medicine, semiconductors, nuclear fuel, propulsion, and national defense have identified the potential need for various enriched isotopes in large quantities. Economically producing most enriched (non-gaseous) isotopes in sufficient quantities has so far eluded commercial producers. The plasma separation process is a commercial technique now available for producing large quantities of a wide range of enriched isotopes. Until recently, this technique has mainly been explored with small-scale (proof-of-principle) devices that have been built and operated at research institutes. The new Theragenics^TM facility at Oak Ridge, TN houses the only existing commercial scale PSP system. This device, which successfully operated in the 1980's, has recently been re-commissioned and is planned to be used to produce a variety of isotopes. This report will summarize the progress and the capabilities of this device and it's potential for impacting the world's supply of stable isotopes in the future. This technique now holds promise of being able to open the door to allowing new and exciting applications of these isotopes in the future.     

A new mass spectrometric method for determining the degree of labeling with heavy isotopes: The study of deuterated toluenes

A new method of general applicability for determining the percentage deuterium labeling in organic compounds is described. It uses the heights of ‘metastable peaks’ in the mass spectrum to determine the relative amounts of deuterated and undeuterated species. The method is illustrated by describing the analysis of mixtures of toluene-o-d₁ and toluene, of toluene α-d₁ and toluene, and of toluene-2,6-d₂, toluene-o-d₁ and toluene.     

Stable isotopes to discriminate lambs fed herbage or concentrate both obtained from C(3) plants

This study was aimed at determining whether isotopic ratio mass spectrometry (IRMS) enables us to discriminate between lambs fed herbage or concentrate, both obtained from C(3) plants, and those fed a concentrate obtained from C(4) plants. Thirty-four Comisana male lambs (age 45 days) were assigned to three feeding treatments. Fourteen lambs were fed vetch (Vicia sativa) ad libitum. Another fourteen lambs received a barley-based concentrate. The remaining six lambs were fed a maize-based concentrate. After 60 days of experimental treatment the animals were slaughtered and the wool, perirenal fat and muscle longissimus dorsi were sampled. The delta(13)C and delta(15)N values of the muscle, wool and feed were measured by continuous flow elemental analysis (CF-EA)-IRMS. The delta(13)C of the fat was determined likewise. The isotopic composition of the tissues reflected that of the three diets. For the lambs which were fed herbage the muscle delta(13)C values were higher (P < 0.0005) and delta(15)N values were lower (P < 0.0005) than those of the lambs receiving concentrates. The delta(15)N and delta(13)C values in the muscle and delta(13)C values in the adipose tissue allowed perfect discrimination between the lambs fed the three different diets. The regression between the delta(13)C values measured in muscle and in wool of lambs was linear (R(2) = 0.99; P < 0.0005). This result shows that delta(13)C measured in the wool can predict muscle delta(13)C distribution, suggesting that wool is a valuable matrix for meat authentication.     

Mass separator for radioactive isotopes

A new isotope separator has been designed, constructed, and put into routine operation for separation of ¹³³Xe providing a major advancement and significant cost reduction in preparation of this radioactive isotope. The design features and advantages are discussed that expedite high purity separation of relatively small quantities of this isotope. These advantages could be easily used to expedite separation of other shorter-lived radioactive isotopes.