A Dempster-type double-focussing mass spectrometer has been used to determine the relative abundances of the isotopes of neodymium using two samples, one irradiated in a strong neutron flux, the other, obtained from the same source, unirradiated. A comparison of these results permits the calculation of the cross-section of each isotope for the capture of pile neutrons. Results previously obtained have been extended to give definite cross-sections for three of the isotopes, two of which have not previously been reported, and to lower the upper limits for the remainder. / Thesis / Master of Science (MS)

Determining the AA availability and metabolism in ruminant is a big challenge due to the rumen fermentation and complicated post absorption utilization. Current techniques used for direct determination of AA absorption and metabolism are laborious and expensive with large variation. The objectives of this project were to investigate AA availability of rumen undegradable protein, develop a stable isotope technique for determination of microbial protein and to evaluate the metabolism of amino acids in mammary glands of dairy cattle using stable isotope-based approaches. In the first experiment, seven heifers (258 ± 28 kg BW) were randomly chosen and assigned to 8 treatment sequences in a 7 x 8, incomplete, Latin square design. Treatments were a basal diet (BD), and 10% (DM basis) of BD replaced by corn silage (CS), grass hay (GH), alfalfa hay (AH), dried distillers grain (DDGS), soybean hulls (SH), wet brewers grain (BG), or corn grain (CG). Individual essential AA availabilities for corn silage, grass hay, alfalfa hay, dried distillers grain, soyhulls, brewers grain and corn grain were 33.4, 29.9, 34.1, 40.6, 28.8, 41.2, and 36.5% of the essential AA in each of the respective ingredients when a loss of 8.27% to splanchnic utilization during first pass was assumed; however, availability varied across individual essential AA. In the second experiment, twelve cows were blocked into 3 groups according to days in milk and randomly assigned to 4 treatments in a repeated 4 x 4 Latin square design with 2 factors to evaluate the essential AA availability from microbial protein and rumen undegradable protein under different rumen fermentation conditions. The 4 treatments were high rumen undegradable protein and high starch (HPHS), low rumen undegradable protein and high starch (LPHS), high rumen undegradable protein and low starch (HPLS) and low rumen undegradable protein and low starch (LPLS). Microbial protein synthesis calculated from purine derivatives was positively associated with rumen degradable protein, which was consistent with total microbial AA entry derived from the isotope dilution model indicating that the isotope based approach was representative. The individual essential AA availability from microbial protein was determined by isotope technique, whereas the PD method was just total PD absorption reflecting CP absorption. The metabolizable AA estimates from NDS nutritional model was similar to results from isotope dilution models, but with smaller difference among treatments. The microbial protein estimated from White's model showed the same trend among treatments compared to isotope dilution model, which may imply it represents the rumen fermentation better. The average essential AA digestibility for microbial AA was 82%, which varied across individual AA and treatments. In the third experiment, four cows (78 ± 10 DIM) were used to study the effects of jugular infusion of 2 groups of AA on essential AA uptake and metabolism by mammary glands in a 4 x 4 Latin square design. Treatments were jugular infusion of saline (CON), methionine plus lysine plus histidine (MKH), isoleucine plus leucine (IL), or MKH plus IL (MKH+IL). The MKH increased milk protein yield in high producing dairy cows. The IL infusion increased milk and milk lactose yields. The production response was associated with a change in mammary plasma flow together with changes in AA uptake and metabolism in mammary gland. Mammary uptake of essential AA was 135 % of milk protein output. Efflux of EAA from the mammary to blood was 13-61% of influx, which was high for BCAA but low for Met and Lys. Changes in influx and efflux resulted in net uptake difference of infused essential AA that were responsive to varying supplies resulting in maintenance of homeostasis. The proportion of AA catabolized and used for milk protein was affected by EAA infusion, which demonstrated plasticity of mammary gland in AA metabolism. Overall, results suggested essential AA availability from rumen undegraded protein and microbial protein varied across individual AA and diets and can be affected by rumen fermentation. After absorption, EAA transport into mammary tissue was bi-directional and their metabolism was affected by AA supply and energy. Using a single coefficient to represent all AA digestibility in MCP or feed ingredient and an integrated efficiency of MP-AA converted into milk protein is inaccurate. / Doctor of Philosophy / Studies in monogastric animals have showed that balancing AA supply with animal requirements can improve the efficiency of N utilization. In order to build a model for AA balanced diet formulation, the composition of feed ingredients, the profile and digestibility of EAA for the rumen undegradable protein and microbial protein, the partition and efficiency of EAA utilization in mammary glands must be determined accurately. However, current AA degradation, digestibility and metabolism data used in nutritional models are from in vitro and in situ studies, which have not been fully validated against in vivo observations. This research used an in vivo stable isotope-based approach to determine amino acid availability for commonly used feed ingredients in dairy industry. The microbial protein AA and rumen undegradable protein AA availability was determined by adapting this isotope technique and introducing another isotope into rumen to label microbes. In addition, by coupling stable isotope tracers with arterio-venous difference technique and compartmental modelling, essential AA metabolism in mammary glands of dairy cows were qualified. Total essential AA availabilities for corn silage, grass hay, alfalfa hay, dried distillers grain, soyhulls, brewers grain and corn grain were similar to values from meta-analysis of mobile bag results, but the availabilities of individual AA were more variable compared to in vitro and in situ results. The model derived microbial AA availability was consistent with the microbial protein calculated from NDS and Felming's model. However, our model predicted a lower proportion of metabolizable AA from microbial protein under diets including low rumen degradable protein, which might imply the NDS nutritional model overestimates microbial protein under low protein diets. The microbial protein estimated from White's model showed the same trend among treatments compared to isotope dilution model, which may imply it represents the rumen fermentation better. The averaged essential AA digestibility form microbial protein was 82%, which varied across individual AA and treatments. After absorption, mammary uptake of essential AA was 135 % of milk protein output. Cellular efflux represented 13 to 61% of essential AA uptake. The proportion of AA catabolized and used for milk protein was affected by essential AA infusion, which demonstrated the plasticity of mammary glands in AA metabolism. In conclusion, the results from isotope technique quantified the essential AA availability from rumen undegradable protein for various feed ingredients and from microbial protein under different feeding conditions. The essential AA transport and metabolism in mammary glands were regulated by multi factors and essential AA supply.

The purpose of this research was to further test a stable isotope based approach as a more reliable in vivo method to determine amino acid bioavailability from a variety of ingredients. The method was used to assess feather meal (FM), blood meal (BM), soybean meal (SBM), and a rumen protected amino acid (RPAA). An abomasal infusion of raw EAAs (isoleucine, leucine and methionine) and an abomasal infusion of sodium caseinate were used as control treatments to test the accuracy of the technique. The isotope-based results were then compared to in situ, in vitro and in vivo test results. The isotope-based technique provided AA bioavailability values for five non-essential AA and seven essential AA. The raw EAA infusion had the greatest AA recovery in plasma with an estimated absorbed RUP value of 93.4± 7.35% followed by the casein infusion (86.7 ± 4.81%), SBM (54.8 ± 5.19%), FM (52.7 ± 4.81%) and BM (47.5 ± 4.81%). The RPAA treatment had the lowest bioavailability at 9.9 ± 12.73%. Numerically, SBM supplied the most absorbable EAA of the 4 feed ingredients, but was not significantly different from that of BM and FM. Simply based on the control treatments in this research (raw EAA and casein), this isotope method was a more accurate method in determining AA bioavailability values with relatively low standard errors. Ingredients are exposed to all aspects of natural digestive processes and the method is able to determine AA appearance in the blood with no use of in situ or in vitro measurements. / Master of Science

Yes / Iron Age chariot burials in the UK are rare and restricted in their distribution. Historically it has been suggested that their Arras culture affinities with Continental Europe, particularly with the Paris basin in France, may be indicative of migration. The majority of them are found on chalk and the putative source region is also chalk. This has meant that a study using only strontium isotopes to identify mobile individuals is problematic. Here we present a range of isotope ratio data (strontium, oxygen, carbon, nitrogen and sulphur) for seven chariot burials from Wetwang, Garton Station and Kirkburn. The majority of them are of men and women who were born and lived locally, although the individual from Kirkburn is likely to have spent his childhood elsewhere. They do, however, differ quite subtly from others in the local population, probably in their relationship to a local land-use pattern operating between two distinct biospheres. / The British Academy provided funding (SG-51722)

Yes / The Bioarchaeology of Care approach developed by Tilley is usually applied to skeletalized human remains, given the usual constraints of preservation bias that are seen with archaeological assemblages. However, other tissues, such as hair are sometimes preserved and can provide a wealth of information that can supplement the skeletal data. Archaeological hair has been analysed for drug compounds for almost thirty years. This article integrates data from hair analyses for coca metabolites, stable light isotope analysis and aDNA to expand the potential of the Bioarchaeology of Care approach using the example of a spontaneously mummified adult female from northern Chile. / Arts and Humanities Research Council, United Kingdom, Doctoral Studentship 2008/140561 (ELB)

This thesis analyzes Donax variabilis from the Burns Site (900 to 1600 CE), located on Cape Canaveral Space Force Station along the Atlantic Coast of Central Florida. Samples were taken along growth lines of 12 Donax variabilis shells from multiple levels of the site. Results show high δ18O values, particularly in the terminal edge of shell growth, indicating cooler conditions at time of harvest. Estimation of temperature from δ18O values provides additional evidence that the D. variabilis sampled in this study were harvested during the autumn or winter. This indicates season of site occupation during these seasons, though occupation during other seasons cannot be ruled out. Sites in northern Florida display similar season of harvest for D. variabilis, potentially indicating that this is a seasonally exploited resource. Additionally, comparing modern sea surface temperatures with those during site occupation shows the time period during which the Burns site was occupied had a similar average temperature with that of modern day, but cooler minimum and maximum temperatures.

The Laramide Rocky Mountains in western U.S.A is an important topographic feature in the continental interior, yet its formation and evolution are poorly constrained. This study uses the oxygen and strontium isotope geochemistry of freshwater bivalve fossils from six Laramide basins in order to reconstruct the spatial evolution of the paleotopography and Precambrian basement erosion in late Cretaceous-early Eocene. In addition it uses the sedimentology, detrital zircon U-Pb geochronology, and isotope paleoaltimetry of early Eocene sedimentary strata to constrain the tectonic setting, paleogeography and paleoclimate of the Wind River basin. Annual and seasonal variation in ancient riverwater δ¹⁸O reconstructed from shell fossils shows that the Canadian Rocky Mountains was 4.5±1.0 km high in late Cretaceous-early Paleocene, and the Laramide ranges in eastern Wyoming reached 4.5±1.3 km high, while the ranges in western Wyoming were 1-2 km high in late Paleocene. The ⁸⁷Sr/⁸⁶Sr ratios of riverwaters reconstructed from the same fossils show that Proterozoic metamorphic carbonates in the Belt-Purcell Supergroup were not exposed in the Canadian Rocky Mountains during Late Cretaceous-early Paleocene, but that Precambrian silicate basement rock was exposed and eroded in the Laramide ranges during late Paleocene-early Eocene. The sedimentary environment of the early Eocene Wind River basin changed from gravelly fluvial and/or stream-dominated alluvial fan to low-sinuosity fluvial systems. Tectonic uplift of the Washakie and Wind River Range in early Eocene formed the modern paleodrainage system, although the elevation of the basin floor was only ~500 m high at that time, and early Eocene paleoclimate is more humid than modern climate.

Applications of lead and strontium isotope analysis were made on archaeological materials from three different contexts in both the Old and New Worlds. These materials comprised pre-Hispanic glaze painted ceramics from Arizona, U.S.A., glass beads from late first millennium AD Igbo-Ukwu, Nigeria, and copper-based metals from early first millennium AD Kissi, Burkina Faso. All materials contain lead at major, minor, or trace concentrations, and lead isotope analysis was employed to determine a provenance for that lead. Strontium isotope analysis also was applied to glass beads from Igbo-Ukwu to determine provenance(s) for strontium found in the glass. Furthermore, application of elemental composition analysis was or had been employed on all samples for additional data comparisons within assemblages and with comparable archaeological materials.Results of these analyses determined, in most cases, regional provenance with high degrees of confidence for lead contained in the analyzed samples. Strontium and elemental composition analysis data also proved valuable in confirming the regional provenance of the raw glass used to produce the glass beads. Leads in the glaze paints from Arizona, which demonstrated a range of resources exploitation, were confidently restricted to a few regions for their procurement. Likewise leads in most glass beads from Igbo-Ukwu were confidently restricted to two main source regions, with a third strong contender also being identified. The elemental composition and strontium isotope data determined with confidence the production regions for the primary raw glasses used to make the glass beads. Finally, leads in copper-based metals from Burkina Faso also were restricted to a few regions, although some inconclusiveness in provenance determination was attributed to mixing of metals from difference sources.These results confirm the utility of heavy isotope analysis of archaeological materials for provenance determination. The combination of these data with elemental composition analyses further confirm the interpretive strength of combining independent but related sets of analytical data for exploring questions of archaeological provenance. With improvements in instrument technology and application in the past two decades, very high precision and high accuracy analyses can be made which eliminate some earlier concerns of heavy isotope applications in archaeology.

The global marine distributions of Cd and phosphate are closely correlated, which has led to Cd being considered as a marine micronutrient. Recent developments in Cd stable isotope mass spectrometry have revealed that Cd uptake by phytoplankton causes isotopic fractionation in the open ocean and in culture. The explanation for this nutrient-like behaviour is unknown as there is only one identified biochemical function for Cd, an unusual Cd/Zn carbonic anhydrase (CdCA1). This thesis investigates why Cd appears to act as an algal nutrient by performing subcellular analyses of microorganisms genetically-modified to express the CdCA1 gene. It was found that CdCA1 was not a significant contributor to whole-cell Cd isotope compositions. Instead, a large proportion of the internalized Cd is sequestered into cell membranes with a similar direction and magnitude of Cd isotopic fractionation as seen in surface seawater. This observation is explained if Cd is mistakenly imported with other divalent metals and subsequently managed by binding within the cell to avoid toxicity. This result implies that surface seawater Cd isotope compositions, if captured by an appropriate archive, may be invaluable for reconstructions of past marine productivity. The role of environmental factors in modulating the inorganic partitioning of Cd isotopes into calcite was investigated through a series of laboratory analogue experiments. In seawater, the light isotopes of Cd are always preferred in calcite. The magnitude of fractionation showed no response to temperature, ambient [Mg], or precipitation rate. To further identify suitable palaeaoceanographic archives, the Cd isotopic composition of a suite of modern deep-sea corals were investigated. It was found that the Cd/Ca and Cd isotope composition of coralline calcium carbonate followed the predicted trend for closed-system Rayleigh fractionation in the calcifying space. The lack of isotopic offsets between some corals and seawater will simplify the application of Cd isotopes in deep-sea corals -- and potentially other marine calcifying organisms that vacuolize seawater prior to calcium carbonate precipitation -- to palaeoceanography.

Hydrogen isotope separation systems using palladium (Pd) are currently being designed for both reactor designs with the aim of separating and purifying the reactor exhaust products which contain valuable unspent hydrogen isotopes. Hydrogen isotope exchange in Pd offers an efficient, ambient condition process that can produce pure isotopic species in a process far simpler and less costly than the current state of the art cryogenic distillation processes. The method is applicable whether separating hydrogen (protium), deuterium or tritium and any combination of these. If practical fusion devices are ever to be realised it is essential to produce an economical and efficient fuel cycle capable of separating and purifying hydrogen isotopes. Hydrogen isotope exchange in Pd is also of interest to the waste separation and purification industries, in particular those using hydrogen separation membranes which used Pd and Pd-alloy membranes. Understanding hydrogen isotope exchange, with particular regard to the formation of the intermediate (and often unwanted) hydrogen deuteride (HD), will aid significantly in future designs of hydrogen isotope separation systems. Novel hydrogen isotope exchange experiments involving hydrogen and deuterium at a number of temperatures (208 K, 293 K and 373 K) and pressures (1.3 bar – 8 bar) not yet explored are presented in this thesis. The experiments were carried out on a unique piece of laboratory apparatus provided to and further developed at the University of Bath. Alongside experimentation, a novel comprehensive multidimensional multi-physics model has been created to analyse the experimental data obtained using the new apparatus and elucidate the kinetics and mechanisms of the reactions occurring between hydrogen isotopic species and Pd during hydrogen isotope exchange based on Langmuir-Hinshelwood surface reaction mechanism. The surface reaction rates, kinetic rate constants and heat effects have been examined in detail, and in tandem, for the first time.