SUMMARY / RELATED TOPICS

Lawrencium

Lawrencium is a synthetic chemical element with the symbol Lr and atomic number 103. It is named in honor of Ernest Lawrence, inventor of the cyclotron, a device, used to discover many artificial radioactive elements. A radioactive metal, lawrencium is the eleventh transuranic element and is the final member of the actinide series. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles. Thirteen isotopes of lawrencium are known. Chemistry experiments have confirmed that lawrencium behaves as a heavier homolog to lutetium in the periodic table, is a trivalent element, it thus could be classified as the first of the 7th-period transition metals: however, its electron configuration is anomalous for its position in the periodic table, having an s2p configuration instead of the s2d configuration of its homolog lutetium. This means that lawrencium may be more volatile than expected for its position in the periodic table and have a volatility comparable to that of lead.

In the 1950s, 1960s, 1970s, many claims of the synthesis of lawrencium of varying quality were made from laboratories in the Soviet Union and the United States. The priority of the discovery and therefore the naming of the element was disputed between Soviet and American scientists, while the International Union of Pure and Applied Chemistry established lawrencium as the official name for the element and gave the American team credit for the discovery, this was reevaluated in 1997, giving both teams shared credit for the discovery but not changing the element's name. In 1958, scientists at the Lawrence Berkeley National Laboratory claimed the discovery of element 102, now called nobelium. At the same time, they attempted to synthesize element 103 by bombarding the same curium target used with nitrogen-14 ions. A follow-up on this experiment was not performed. Eighteen tracks were noted, with decay energy around 9±1 MeV and half-life around ​1⁄4 s. While the data agrees reasonably with that discovered for 257Lr, the evidence obtained in this experiment fell far short of the strength required to conclusively demonstrate the synthesis of element 103.

In 1960, the Lawrence Berkeley Laboratory attempted to synthesize the element by bombarding 252Cf with 10B and 11B. The results of this experiment were not conclusive; the first important work on element 103 was carried out at Berkeley by the nuclear-physics team of Albert Ghiorso, Torbjørn Sikkeland, Almon Larsh, Robert M. Latimer, their co-workers on February 14, 1961; the first atoms of lawrencium were produced by bombarding a three-milligram target consisting of three isotopes of the element californium with boron-10 and boron-11 nuclei from the Heavy Ion Linear Accelerator. The Berkeley team reported that the isotope 257103 was detected in this manner, that it decayed by emitting an 8.6 MeV alpha particle with a half-life of 8±2 s. This identification was corrected to be 258103, as work proved that 257Lr did not have the properties detected, but 258Lr did; this was considered at the time to be convincing proof of the synthesis of element 103: while the mass assignment was less certain and proved to be mistaken, it did not affect the arguments in favor of element 103 having been synthesized.

Scientists at the Joint Institute for Nuclear Research in Dubna raised several criticisms: all but one were answered adequately. The exception was that 252Cf was the most common isotope in the target, in the reactions with 10B, 258Lr could only have been produced by emitting four neutrons, emitting three neutrons was expected to be much less than emitting four or five; this would lead to a narrow yield curve, not the broad one reported by the Berkeley team. A possible explanation was that there was a low number of events attributed to element 103; this was an important intermediate step to the unquestioned discovery of element 103, although the evidence was not convincing. The Berkeley team proposed the name "lawrencium" with symbol "Lw", after Ernest Orlando Lawrence, inventor of the cyclotron; the IUPAC Commission on Nomenclature of Inorganic Chemistry accepted the name, but changed the symbol to "Lr". This acceptance of the discovery was characterized as being hasty by the Dubna team. 25298Cf + 115B → 263103Lr* → 258103Lr + 5 10nThe first work at Dubna on element 103 came in 1965, when they reported to have created 256103 in 1965 by bombarding 243Am with 18O, identifying it indirectly from its granddaughter fermium-252.

The half-life they reported was somewhat too high due to background events. 1967 work on the same reaction identified two decay energies in the ranges 8.35–8.50 MeV and 8.50–8.60 MeV: these were assigned to 256103 and 257103. Despite repeated attempts, they were unable to confirm assignment of an alpha emitter with a half-life of eight seconds to 257103; the Russians proposed the name "rutherfordium" for the new element in 1967: this name was used for element 104. 24395Am + 188O → 261103Lr* → 256103Lr + 5 10nFurther experiments in 1969 at Dubna and in 1970 at Berkeley demonstrated an actinide chemistry for the new element, so that by 1970 it was known that element 103 is the last actinide. In 1970, the Dubna group reported the synthesis of 255103 with half-life 20 s and

Aguas frescas

Aguas frescas are light non-alcoholic beverages made from one or more fruits, flowers, or seeds blended with sugar and water. They are popular in Central America and the United States; some of the more common flavors include tamarind and horchata. Aguas frescas are sold by street vendors, but can be found in bodegas and juice bars. There is some confusion in terms internationally between the drinks referred to here and bottled soft drinks. In Guatemala and Nicaragua, these are referred to as frescos, short for refresco, which in Mexico means soft drinks. Soft drinks in Guatemala are called aguas, short for aguas gaseosas, but confused with the Mexican aguas frescas. In Mexico, it is common to find aguas frescas in these flavors: Cantaloupe Grape Guava Mango Melon Prickly Pear Orange Papaya Passion fruit Soursop Strawberry Watermelon Raspberry Cucumber Lemon Lime Pineapple Tamarind Chía blended with vegetables Horchata Cebada Hibiscus tea called agua de Jamaica or sorrel, popular in Jamaica and West Africa Alfalfa Licuados Paletas Samalamig

David R. Lindberg

David R. Lindberg is an American malacologist and professor of integrative biology at the University of California, Berkeley, he is the Curator for the University of California Museum of Paleontology and co-editor of the journal Molecular Systematics and Phylogeography of Mollusks. Much of his work has focused on sea snails on limpets, on the phylogeny of the Patellogastropoda, various other gastropod groups. Lindberg renamed the order Docoglossa to Patellogastropoda in 1986, he is notable for naming the subclass Eogastropoda, proposing that the taxonomy of the Gastropoda be rewritten in terms of monophyletic groups. Although these species were named in honor of one or more people who had the surname Lindberg, judging from the year the species were named, only a few of the following taxa were named in honor of David R. Lindberg. Bathyglycinde lindbergi Bathyraja lindbergi Ishiyama & Ishihara, 1977 Bogidiella lindbergi Ruffo, 1958 Cyclopteropsis lindbergi Soldatov, 1930 Dugesia lindbergi de Beauchamp, 1959 Eualus lindbergi Kobyakova, 1955 Genioliparis lindbergi Andriashev & Neyelov, 1976 Glycinde lindbergi Uschakov, 1955: synonym of Bathyglycinde lindbergi Gobio gobio lepidolaemus natio lindbergi Turdakov & Piskarev, 1955: synonym of Gobio gobio gobio Gurjanovilia lindbergi Jakovleva, 1952: synonym of Tripoplax lindbergi Hadropogonichthys lindbergi Fedorov, 1982 Halicyclops lindbergi Rocha C.

E. F. 1995 Iothia lindbergi McLean, 1985 Lindbergichthys Lindbergichthys mizops: synonym of Lepidonotothen mizops Lindbergichthys nudifrons: synonym of Lepidonotothen nudifrons Liparis lindbergi Krasyukova, 1984: synonym of Liparis latifrons Schmidt, 1950 Lottia lindbergi Sasaki & Okutani, 1994 Lycodes lindbergi Popov, 1931: synonym of Lycodes uschakovi Popov, 1931 Machilis lindbergi Wygodzinsky, 1959 Mesochra lindbergi Petkovski, 1964 Mycale lindbergi Koltun, 1958 Peramphithoe lindbergi Potamon gedrosianum lindbergi Pretzmann, 1966: synonym of Potamon ruttneri Pretzmann, 1962 Sarothrogammarus lindbergi G. Karaman, 1969 Scoiiodota lindbergi D'yakonov in D'yakonov et al. 1958: synonym of Scoliodotella lindbergi Scoliodota lindbergi Scoliodotella lindbergi Tripoplax lindbergi Taxonomy of the Gastropoda Webpages for LindLab at Berkeley His profile at Berkeley