Search results for "ISOTOPE"
showing 10 items of 2232 documents
Bacillus thuringiensis Cry1Ac Toxin-Binding and Pore-Forming Activity in Brush Border Membrane Vesicles Prepared from Anterior and Posterior Midgut R…
2008
ABSTRACT It is generally accepted that Bacillus thuringiensis Cry toxins insert into the apical membrane of the larval midgut after binding to specific receptors, and there is evidence that the distribution of binding molecules along the midgut is not uniform. By use of the voltage-sensitive dye DiSC 3 (5) and 125 I-labeled Cry1Ac, we have measured the effect of Cry1Ac in terms of permeabilization capacity and of binding parameters on brush border membrane vesicles (BBMV) prepared from the anterior and the posterior regions of the larval midgut from two insect species, Manduca sexta and Helicoverpa armigera . The permeabilizing activity was significantly higher with BBMV from the posterior …
Response of Chinese Hamster V79 Multicellular Spheroids Exposed to High-Energy Carbon Ions
2004
Chinese hamster V79-379A spheroids 200 +/- 30 microm (+/- SD) in diameter were irradiated in agitated medium in different oxygen atmospheres with (1) 227 MeV/nucleon (12)C(+6) ions (plateau region) to model tissue in the entrance channel during therapy, (2) carbon ions in the extended Bragg peak modeling tissue in the target volume, or (3) X rays as a reference modality. Cell survival curves were similar for modes (1) and (3), indicating the absence of a contact effect and the presence of a pronounced oxygen effect with oxygen enhancement ratios (OERs) of 2.8 and 2.9, respectively. In contrast, the oxygen effect was substantially smaller in mode (2) with an OER of 1.4. Under normal or restr…
Effect of L-Histidine on the Survival of a T-Strain of Mycoplasma
1975
The addition of L-histidine to the growth medium prolongs the stationary phase and the survival of a T-strain of mycoplasma. Results of an experiment performed with 14 C-labeled urea demonstrate that the action of L-histidine is based on the retardation of the rise of pH.
Continuous separation and identification of neutronrich neptunium isotopes from heavy-ion reactions by means of the centrifuge system “sisak”
1986
Abstract Neutron-rich neptunium isotopes formed in direct transfer reactions between 136 Xe projectiles and targets of 244 Pu have been separated from other reaction products with the on-line liquid-liquid extraction system SISAK. A four-detector delay method was used to determine the half-lives of the previously unknown isotopes 243 Np and 244 Np. From the decay of the 287.4 keV γ-line a half-life of 1.8 ± 0.3 min was determined for 243 Np. From the decay curves of the γ-lines at 162.7 and 216.7 keV, which fit into the known level scheme of 244 Pu, a half-life of 2.5 ± 0.3 min results for 244 Np.
Strontium/lithium ratio in aragonitic shells of Cerastoderma edule (Bivalvia) — A new potential temperature proxy for brackish environments
2015
Abstract Quantitative reconstruction of water temperature from shells of bivalve mollusks is still a very challenging task. For example, in highly variable environments such as intertidal zones, shell oxygen isotope values can only provide reliable temperature estimates if the δ18Owater signature during the time of growth is known. Furthermore, trace element-to-calcium ratios such as Sr/Ca or Mg/Ca often do not serve as reliable paleothermometers, because their incorporation into bivalve shells is known to be strongly biologically controlled. Here, we present a potential novel temperature proxy which is based on the Sr/Lishell ratio of the intertidal bivalve Cerastoderma edule. Up to 81% of…
Isotope shifts in natural cerium
2003
High resolution crossed beam resonance fluorescence laser spectroscopy has been performed on an atomic beam of naturally occurring cerium, and isotope shifts have been measured in several transitions. Changes in mean square charge radius, δ〈r 2〉, have been extracted using the King plot technique and show the characteristic increase at the N = 82 neutron shell closure. The measurements form the basis for further investigations of radioactive isotopes and isomers on both sides of the shell closure.
Enhanced quantum sieving of hydrogen isotopes via molecular rearrangement of the adsorbed phase in chabazite
2020
Coadsorption experiments reveal an unexpected increase of the D2/H2 selectivity with loading in pure silica chabazite at 47 K. This effect is correlated with the appearance of a step in the adsorption isotherms of H2 and D2. Grand canonical Monte Carlo simulations show that this phenomenon is related to a molecular rearrangement of the adsorbed phase induced by its strong confinement. In the case of a H2 and D2 mixture, this rearrangement favors the adsorption of D2 having a smaller size due to quantum effects.
Direct identification of 103–107Mo by a rapid chemical separation procedure
1977
Abstract The nuclides 103–107Mo have been identified by means of γ-ray spectroscopy after the separation of molybdenum from fission products of 235U and 239Pu by a rapid chemical procedure. Half-lives of 67.5 ± 1.5 s for 103Mo, 59.4 ± 0.8 s for 104Mo, 36.7 ± 1.0 s for 105Mo, 8.4 ± 0.5 s for 106Mo and 3.5 ± 0.5 s for 107Mo have been determined and the main γ-lines were assigned to the decay of these isotopes. Some evidence for 108Mo with a half-life ≤2 s has also been obtained.
Decay properties of neutron-rich niobium isotopes
1976
The decay of neutron-rich niobium isotopes in the mass region $A\ensuremath{\simeq}100$ has been investigated by $\ensuremath{\gamma}$-ray singles and $\ensuremath{\gamma}$-$\ensuremath{\gamma}$ coincidence measurements. The isotopes were produced by thermal-neutron induced fission of $^{235}\mathrm{U}$, $^{239}\mathrm{Pu}$, and $^{249}\mathrm{Cf}$, and niobium was separated from fission-product mixtures with an automated chemical procedure. Isomerism was found in the even-mass niobium isotopes with the following half-lives: 1.5 and 3.1 sec for $^{100}\mathrm{Nb}$, 1.3 and 4.3 sec for $^{102}\mathrm{Nb}$, and 0.8 and 4.8 sec for $^{104}\mathrm{Nb}$. Half-lives and $\ensuremath{\gamma}$ rays…
An EC-branch in the decay of 27-s 263Db: Evidence for the isotope 263Rf
2003
Summary 27-s 263Db was produced in the 249Bk ( 18O, 4n) reaction at 93 MeV. The activity was transported by a He/KCl-jet to the laboratory where it was collected for 15 min and then subjected to a chemical separation specific for group-4 elements. The activity was dissolved in 0.5 M unbuffered α-HiB and eluted from a cation-exchange column. The effluent was made 9 M in HCl and group-4 tetrachlorides were extracted into TBP/Cyclohexane which was evaporated to dryness on a Ta disc. The Ta discs were assayed for α and SF activity. A SF activity with a half life on the order of 20 min was observed and assigned to the nuclide 263Rf. It is formed by electron-capture decay of 263Db with a decay br…