F. A. Rickey

In vivo degradation of 14C-labeled small intestinal submucosa (SIS) when used for urinary bladder repair.

The rate of in vivo degradation was determined for a naturally occurring biomaterial derived from the extracellular matrix of the small intestinal submucosa (SIS). The SIS was labeled by giving weekly intravenous injections of 10 microCi of 14C-proline to piglets from 3 weeks of age until the time of sacrifice at 26 weeks. The resultant SIS prepared from these pigs contained approximately 10(3) fold more 14C than unlabeled tissues. The labeled SIS was used to repair experimental defects in the urinary bladder of 10 dogs. The animals were sacrificed at post-operative times ranging from 3 days to 1 year and the remodeled urinary bladder tissue was harvested for evaluation of 14C by a combination of liquid scintillation counting and accelerator mass spectrometry. The remodeled tissue contained less than 10% of the 14C (disintegrations per minute/gram tissue wet weight) at 3 months post-surgery compared to the SIS biomaterial that was originally implanted. The SIS scaffold was replaced by host tissue that resembled normal bladder both in structure and function. After implantation, 14C was detected in highest concentrations in the blood and the urine. The SIS bioscaffold provides a temporary scaffold for tissue remodeling with rapid host tissue remodeling, degradation, and elimination via the urine when used as a urinary bladder repair device.

PRIME lab AMS performance, upgrades and research applications

Abstract The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is a dedicated research and service facility for AMS that provides the scientific community with timely, reliable and high quality chemical processing (∼600 samples/year) and AMS measurements (∼3000 samples/year) of 10 Be, 14 C, 26 Al, 36 Cl, 41 Ca and 129 I. The AMS system is based on an upgraded FN (7 MV) tandem accelerator that has recently been modified to improve performance. The precision is 1% for 14 C and it is 3–5% for the other nuclides for radioisotope/stable isotope ratios at the 10 −12 levels. System background for 10 Be, 14 C, 26 Al, 36 Cl and 41 Ca is 1–10×10 −15 while for 129 I the natural abundance limits it to 20×10 −15 . Research is being carried out in Earth, planetary, and biomedical sciences. Geoscience applications include determination of exposure ages of glacial moraines, volcanic eruptions, river terraces, and fault scarps. Burial histories of sand are being determined to decipher the timing of human expansion and climatic history. Environmental applications are tracing the release of radioactivity from nuclear fuel reprocessing plants, water tracing, and neutron dosimetry. The applications using meteoric nuclides are oil field brines, sediment subduction, radiocarbon dating, and groundwater 36 Cl mapping. Radionuclide concentrations are also determined in meteorites and tektites for deciphering space and terrestrial exposure histories.

Status and plans for the PRIME Lab AMS facility

Abstract The operation, status, performance, and upgrade plans for the Purdue Rare Isotope Measurement Laboratory (PRIME Lab) are described. The AMS system is in routine operation for all of the commonly-used AMS nuclides. Chemical preparation is being performed for all nuclides measured in many different matrices. Construction of a new injector and terminal stripper system is in progress; a fast-isotope-switching system is in the final design stage.

Re-generation of tissue about an animal-based scaffold: AMS studies of the fate of the scaffold

Abstract Small intestinal submucosa (SIS) is an unusual tissue, which shows great promise for the repair of damaged tissues in humans. When the SIS is used as a surgical implant, the porcine-derived material is not rejected by the host immune system, and in fact stimulates the constructive re-modeling of damaged tissue. In dogs, these SIS scaffolds have been used to grow new arteries, tendons, and urinary bladders. Moreover, the SIS scaffold tissue seems to disappear from the implant region after a few months. The fate of this SIS tissue is of considerable importance if it is to be used in human tissue repair. SIS is obtained from pigs. We have labeled the SIS in several pigs by intraveneous administration of 14 C enriched proline from the age of three weeks until they reach market weight. The prepared SIS was then implanted in dogs as scaffolds for urinary bladder patches. During the remaining life of each dog, blood, urine and feces samples were collected on a regular schedule. AMS analyses of these specimens were performed to measure the elimination rate of the SIS. At different intervals, the dogs were sacrificed. Tissue samples were analyzed by AMS to determine the whole-body distribution of the labeled SIS.

Levels of 108Cd populated in the 96Zr(16O, 4nγ)108Cd reaction☆

Abstract Levels in 108Cd were studied using the reaction 96 Zr ( 16 O , 4nγ) 108 Cd with a bombarding energy of 56 MeV. The experiments included γ-ray yields as a function of bombarding energy, γ-ray angular distributions, γ-ray linear polarizations and γ-γ coincidence measurements. The decay scheme which includes 48 γ-ray transitions is very similar to those reported for even-even Pd isotopes. In addition to the ground-state band, there appear to be four collective bands built on two-quasiparticle states. The results are in excellent agreement with a slightly deformed rotor description of the 108Cd nucleus.

The Purdue Rare Isotope Measurement Laboratory

Abstract Purdue University has brought into operation a new NSF/NASA facility dedicated to accelerator mass spectrometry. Based on a 7.5 MV FN tandem, 10Be, 26Al, and 36Cl are being measured at a rate of 1500 samples per year. Research involves primarily 1) earth science studies using cosmogenic radionuclides produced in the atmosphere and measured in rain, groundwater, and soils, 2) Quaternary geomorphology and climatology studies using in-situ produced radionuclides, 3) planetary science studies using a wide variety of meteorites and radionuclides, and 4) biomedical tracer studies using 26Al.

Pixe Analysis of Water with Detection Limits in the PPB Range

The excellent sensitivity and broad range of the PIXE technique suggests that it can be an attractive method for the multielemental analysis of water. The basic nature of water samples however presents several challenges to the analist, in particular sample preparation, efficient data collection, and data analysis. The Purdue University PIXE system has been developed to overcome these difficulties. The system has been used to analyze a large number of samples where the concentration ratio of abundant to trace elements is as large as 106. Detection limits obtained for most elements are in the range 0.1 to 5 ppb.

Collective and two-quasiparticle excitations inPd102,104,106following (C13,3nγ) reactions

Even-A Pd nuclei were studied using the reactions /sup 92/,/sup 94/,/sup 96/Zr(/sup 13/C,3n..gamma..)/sup 102/,/sup 104/,/sup 106/Pd. The experiments included ..gamma..-ray yield as a function of energy, ..gamma..-ray angular distributions, ..gamma..-ray linear polarizations, and ..gamma..-..gamma.. coincidence measurements. A new treatment of ..gamma..-..gamma.. directional correlation from oriented nuclei, which combines data from all appropriate coincidence pairs to reduce uncertainties, has aided in determining multipolarities for 49 contaminated transitions. Extensive decay schemes are presented which include many high-angular-momentum, positive- and negative-parity states. In addition to the ground-state band, there appear to be three collective bands built on excited two-quasiparticle states. The measurements favor a slightly deformed rotor description of these nuclei over an interpretation in terms of a vibrational (interacting boson) model. (AIP)

Symmetric rotor interpretation of transitional nuclei

Abstract A rotational interpretation in the strong coupling limit is applied to transitional nuclei in the mass-70, -100, -120 regions. The calculations use a symmetric rotor with relatively small deformation and a variable moment of inertia is included explicitly. It is shown that this simple model, which is essentially similar to that used for strongly deformed nuclei, is in good agreement with a wide range of phenomena observed in transitional nuclei. Energy levels, branching ratios, and mixing ratios are included in the comparison to experimental data.

The PRIME Lab biomedical program

Abstract The biomedical accelerator mass spectrometry (AMS) initiative at PRIME Lab including the status of equipment and sample preparation is described. Several biomedical projects are underway involving one or more of the nuclides: 14C, 26Al and 41Ca. Routine production of CaF2 and graphite is taking place. Finally, the future direction and plans for improvement of the biomedical program at PRIME Lab are discussed.