A nuclear forensics investigation involving a uranium ore concentrate relies on accurate and precise analysis of impurities. Analytical data defensibility requires the use of reference materials as ...part of quality control. This study presents a compilation of trace element concentration results of the CUP-2 Uranium Ore Concentrate Standard measured by 11 different laboratories. The laboratories employed various dissolution methods, analytical preparation methods, and instrumental platforms. The data presented here contain concentrations of 66 impurities with up to 138 individual data points for each impurity. Consensus values have been assigned to each impurity following a statistical analysis of the data set.
Trace impurity patterns are important nuclear forensic signatures in uranium ore concentrates (UOCs) and Certified Reference Materials (CRMs) are used to validate the analysis methods employed by end ...users. Herein, we discuss the certification campaign for three new UOC CRMs from the National Research Council Canada: UCLO-1 (
https://doi.org/10.4224/crm.2020.uclo-1
), UCHI-1 (
https://doi.org/10.4224/crm.2020.uchi-1
), and UPER-1 (
https://doi.org/10.4224/crm.2020.uper-1
). This study involved 15 laboratories from 10 countries, using sector-field and (triple) quadrupole inductively-coupled plasma mass spectrometry to analyze 64 trace element impurities. We discuss the importance of the acids used for sample digestion, difficulties analyzing in a high uranium matrix, and data combination and uncertainty evaluation for this large dataset.
Clear differences in the elemental composition of the stomachs of adult Mysis relicta Lovén captured on or near the lake bottom during the day and those captured at night in the water column were ...observed using laser ablation - inductively coupled plasma - mass spectrometry. The elemental composition of the stomachs of mysids captured at night indicated that they were feeding on zooplankton and algae, whereas the stomachs of those captured during the day indicated sediment feeding. These results suggest that lake sediments may be a significant part of the mysid diet and that sediments transported vertically as gut contents may contribute to the transport of elements into the water column.
Herein, a nuclear forensics investigation involving a uranium ore concentrate relies on accurate and precise analysis of impurities. Analytical data defensibility requires the use of reference ...materials as part of quality control. This study presents a compilation of trace element concentration results of the CUP-2 Uranium Ore Concentrate Standard measured by 11 different laboratories. The laboratories employed various dissolution methods, analytical preparation methods, and instrumental platforms. The data presented here contain concentrations of 66 impurities with up to 138 individual data points for each impurity. Consensus values have been assigned to each impurity following a statistical analysis of the data set.
γ-Aminobutyric acid （GABA） is the major inhibitory neurotransmitter in the central nervous system. The termination of GABA transmission is through the action of a family of membrane proteins, called ...GABA transporters （GAT1-4）. It is well established that GABA system is involved in the modulation of memory. Our previous study showed that homozygous GAT1^-/- mice exhibited impaired hippocampus-dependent learning and memory. To evaluate the impact of endogenous reduced GABA reuptake on mice cognitive behaviors, the ability of learning and memory of heterozygous GAT1^＋/- mice was detected by the passive avoidance paradigm and Morris water maze. The hole board paradigm was also used to measure changes in anxiety-related behavior or exploratory behav- ior in such mice. As one form of synaptic plasticity, long- term potentiation was recorded in the mouse hippocampal CA1 area. We found that GAT1^＋/- mice displayed increased learning and memory, decreased anxiety-like behaviors, and highest synaptic plasticity compared with wild-type and homozygous GAT1^-/- mice. Our results suggest that a moderate reduction in GAT1 activity causes the enhancement of learning and memory in mice.
An effective and practical strategy has been established for the direct and site‐selective arylation of indoles at the C4 and C5 positions with the aid of a readily accessible, cheap, and removable ...pivaloyl directing group at the C3 position. This transformation shows good functional‐group tolerance and could serve as a powerful synthetic tool for the synthesis of medicinally relevant compounds. This method and those developed in previous research together enable the regiocontrolled direct arylation of indole at each C−H bond without prefunctionalization of the reactive sites.
Grand Slam: An effective and practical strategy has been established for the direct site‐selective arylation of indoles at the C4 or C5 position (see scheme) by the use of a readily available and removable pivaloyl directing group (DG) at the indole C3 position. Now the direct site‐selective arylation of indoles at any given C−H bond is possible by the appropriate choice of this or a previously developed complementary method.
Cu-Catalyzed Direct C6-Arylation of Indoles Yang, Youqing; Li, Ruirui; Zhao, Yue ...
Journal of the American Chemical Society,
07/2016, Letnik:
138, Številka:
28
Journal Article
Recenzirano
The first example of direct and site-selective arylation of indoles at the C6 position has been reported. The key to this high regioselectivity is the appropriate choice of the N–P(O) t Bu2 ...directing group and the use of diaryliodonium triflate salts as the coupling partners in the presence of catalytic CuO. The protocol is distinguished by mild reaction system that avoids ligand and additives, exhibiting wide scope of indole and arene coupling components without compromising its efficiency and scalability, thus representing a significant advancement in the implementation of regioselective direct arylation of indoles.
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