Some of the techniques used in atom-at-a-time investigations of both nuclear and chemical properties of transactinide elements
will be discussed. Constraints on the systems that are valid for exploring chemical properties when only a few atoms at a
time are available and recent developments in instrumentation are considered. The current status of investigations of the
chemical properties of the transactinides is summarized and prospects for additional studies are evaluated.
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.
The long quest to detect SuperHeavy Elements that might exist in nature or to artificially synthesize them at accelerators is briefly reviewed. The very recent reports of the production and detection of the SuperHeavy Elements 114, 116, and 118 at accelerators are discussed. The implications of these discoveries and the prospects for the existence and discovery of additional heavy elements are considered.
The interactions between experimental discoveries in low-energy nuclear fission and our theoretical understanding of the structure of the nucleus are reviewed. The history of this synergistic relationship begins with the discovery of fission, the development of the liquid-drop model and the experimental evidence for magic numbers, continues through the development of the shell model, the experimental discovery of shape isomerism, the double-humped fission barrier resulting from theoretical calculations of shell corrections to the liquid-drop model, the spontaneous fission half-life disaster, the discovery of symmetric mass division in spontaneous fission and theoretical treatments based on different paths to scission. It concludes with a brief review of our current experimental and theoretical understanding of low-energy fission and the prospects for future developments.
The major contributions of G. T. Seaborg to nuclear science, including co-discovery of many isotopes with practical applications in medicine and industry, co-discovery of plutonium and nine more transuranium elements, the actinide hypothesis, and searches for superheavy elements are briefly summarized. His enduring interest in science education, the history of science, and public affairs are also noted.
Authors:J. Schwantes, R. Sudowe, H. Nitsche, and D. Hoffman
A novel multi-process method for separating Eu from neighbouring lanthanides (Ln) has been developed that chemically reduces
Eu(III) to Eu(II) prior to solvent extraction of Ln(III) with thenoyltrifluoroacetone in benzene. This method is capable of
achieving higher purities (>99%) and separation yields than previously published multi-process methods that stabilize and
separate the reduced Eu(II) as a sulphate solid and is ideal for enriching materials of high-value. Results from a variety
of combinations of a chemical or electrochemical reduction process preceding a separation process using either ion-exchange
chromatography, reversed phase chromatography, or solvent extraction are discussed.
Polistes dominulus is known to be an allergenically important social wasp. Its venom has four major allergens (ziv. phospholipase A1, hyaluronidase, antigen 5 and a serine-protease). Amino acid sequences of its serine-protease and Antigen 5 have been published. In this paper, the partial amino acid sequence of its venom phospholipase native protein is reported. Also, we give an account to the complete nucleotide sequence of Polistes dominulus venom phospholipase A1 gene, its isoforms and their complete deduced amino acid sequences. Their similarity to the other phospholipases A1 of the family: Vespidae is discussed.
Authors:D. Moir, K. Ross, J. Chen, A. Tarr, E. Bialas, W. Boivin, D. Doern, D. Hoffman, and J. Ross
Spent ion-exchange resins are produced in the purification of coolant and moderator systems during the normal operation of CANDU (Canada deuterium uranium) nuclear reactors. Carbon-14 is a radionuclide of concern in disposal of ion-exchange resins because of its relatively long half-life, its potential high mobility and its ability to be easily incorporated into organisms. Only limited data are presently available on the14C concentrations of spent from CANDU reactors. To establish a more comprehensive datahase for this radionuclide, concentrations of14C were determined for two moderator resins from Bruce Nuclear Generating Station A. Mixed bed resins were separated into anion and cation fractions using a sugar solution, and the14C concentrations were determined for each fraction. Carbon-14-was located predominantly on the anion beads. Samples of anion resin were found to undergo an 81% loss in the14C concentration over a period of 160 d following the sugar separation procedure. Some evidence is given to suggest this loss in14C may result from microbial activity. Concentrations and distributions of other predominant radionuclides, such as60Co and153Gd, are discussed as well.
Authors:D. Hoffman, R. Henderson, K. Gregorich, D. Bennett, R. Chasteler, C. Gannett, H. Hall, D. Lee, M. Nurmia, S. Cai, R. Agarwal, A. Charlop, Y. Chu, G. Seaborg, and R. Silva
The isotope260Lr, produced in reactions of18O with249Bk, was used to perform chemical experiments on lawrencium to learn more about its chemical properties. These experiments involved extractions with thenoyl trifluoroacetate, elutions from cation exchange resin columns with ammonium alpha-hydroxyisobutyrate, and reverse-phase chromatography using hydrogen di(2-ethylhexyl) orthophosphoric acid to investigate the chemical properties of Lr. The results from the elutions gave information about the ionic radius of Lr(III) which was found to elute very close to Er. An attempt to reduce Lr(III) with hydroxylamine hydrochloride was unsuccessful.
Authors:A. Türler, H. Gäggeler, K. Gregorich, H. Barth, W. Brüchle, K. Czerwinski, M. Gober, N. Hannink, R. Henderson, D. Hoffman, D. Jost, C. Kacher, B. Kadkhodayan, J. Kovacs, J. Kratz, S. Kreek, D. Lee, J. Leyba, M. Nurmia, M. Schädel, U. Scherer, Schimpf, D. Vermeulen, A. Weber, H. Zimmermann, and I. Zvara
On-line isothermal gas phase chromatography was used to study halides of261104 (T1/2=65 s) and262,263105 (T1/2=34 s and 27 s) produced an atom-at-a time via the reactions248Cm(18O, 5n) and249Bk(18O, 5n, 4n), respectively. Using HBr and HCl gas as halogenating agents, we were able to produce volatile bromides and chlorides of the above mentioned elements and study their behavior compared to their lighter homologs in Groups 4 or 5 of the periodic table. Element 104 formed more volatile bromide than its homolog Hf. In contrast, element 105 bromides were found to be less volatile than the bromides of the group 5 elements Nb and Ta. Both 104 and Hf chlorides were observed to be more volatile than their respective bromides.