228,814 research outputs found
C-H-activated aluminum hydroxide via molecular oxygen
No full textThe reaction of LAl[eta(2)-(C-2(SiMe3)(2))] (1; L = HC[(CMe)(NDipp)](2), Dipp = 2,6-iPr(2)C(6)H(3)) with dioxygen leads to the elimination of bis(trimethylsilyl)acetylene and the formation of the corresponding aluminum monohydroxide via the oxidation of one of the CHMe2 groups on the Dipp ring
Synthesis of L-glucose and L-galactose derivatives from D-sugars
No full textAn efficient route to prepare L-glucose and L-galactose is described. The L-sugars are achieved by using the strategy of switching the functional groups at C1 and C5 of D-glucose and D-mannose. The oxidation and reduction of the silyl enol ether at C1 and the lead(IV) tetraacetate mediated oxidative decarboxylation at C5 are the key steps. L-Glucose and L-galactose are prepared in a convenient and inexpensive way. (C) 2014 Shu-Chun Li and Zhong-Jun Li. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000345880500003&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, MultidisciplinarySCI(E)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)[email protected]; [email protected]
Rotationally resolved infrared spectrum of the Li+-D-2 cation complex
No full textThe infrared spectrum of mass selected Li+-D-2 cations is recorded in the D-D stretch region (2860-2950 cm(-1)) in a tandem mass spectrometer by monitoring Li+ photofragments. The D-D stretch vibration of Li+-D-2 is shifted by -79 cm(-1) from that of the free D-2 molecule indicating that the vibrational excitation of the D-2 subunit strengthens the effective Li+center dot D-2 intermolecular interaction. Around 100 rovibrational transitions, belonging to parallel K-a=0-0, 1-1, and 2-2 subbands, are fitted to a Watson A-reduced Hamiltonian to yield effective molecular parameters. The infrared spectrum shows that the complex consists of a Li+ ion attached to a slightly perturbed D-2 molecule with a T-shaped equilibrium configuration and a 2.035 A vibrationally averaged intermolecular separation. Comparisons are made between the spectroscopic data and data obtained from rovibrational calculations using a recent three dimensional Li+-D-2 potential energy surface [R. Martinazzo, G. Tantardini, E. Bodo, and F. Gianturco, J. Chem. Phys. 119, 11241 (2003)]. (c) 2006 American Institute of Physics
Measurements of K S 0 - K L 0 asymmetries in the decays Λ c + → p K L , S 0 , p K L , S 0 π + π − and p K L , S 0 π 0
No full textAbstract Using e + e − annihilation data sets corresponding to an integrated luminosity of 4.5 fb −1, collected with the BESIII detector at center-of-mass energies between 4.600 and 4.699 GeV, we report the first measurements of the absolute branching fractions B Λ c + → p K L 0 = (1.67 ± 0.06 ± 0.04)%, B Λ c + → p K L 0 π + π − = (1.69 ± 0.10 ± 0.05)%, and B Λ c + → p K L 0 π 0 = (2.02 ± 0.13 ± 0.05)%, where the first uncertainties are statistical and the second systematic. Combining with the known branching fractions of Λ c + → p K S 0 , Λ c + → p K S 0 π + π − , and Λ c + → p K S 0 π 0 , we present the first measurements of the K S 0 - K L 0 asymmetries R Λ c + K S , L 0 X = B Λ c + → K S 0 X − B Λ c + → K L 0 X B Λ c + → K S 0 X + B Λ c + → K L 0 X in charmed baryon decays: R Λ c + p K S , L 0 = − 0.025 ± 0.031 , R Λ c + p K S , L 0 π + π − = − 0.027 ± 0.048 and R Λ c + p K S , L 0 π 0 = − 0.015 ± 0.046 . No significant asymmetries with statistical significance are observed
Hyllus C. L. Koch 1846
No full textGenus Hyllus C. L. Koch, 1846 Type species. Hyllus giganteus C. L. Koch, 1846 from Indonesia.Published as part of Lin, Yejie, Zhao, Huifeng, Koh, Joseph K H & Li, Shuqiang, 2022, Taxonomy notes on twenty-eight spider species (Arachnida: Araneae) from Asia, pp. 198-270 in Zoological Systematics 47 (3) on page 230, DOI: 10.11865/zs.2022303, http://zenodo.org/record/717585
A new genus Clypeolontha Li and Yang, for the genus Melolontha Fabricius (Coleoptera: Scarabaeidae: Melolonthinae) from Southeastern Asia
No full textLi-mediated N2 reduction reaction into NH3: recent outcomes and the SuN2rise Li-N2 cells concept
No full textOperating in severe conditions (at least 450 °C and, in particular, 200 atm), the Haber-Bosh (HB) process is responsible of around 1.44% of the global greenhouse gas emissions. To find a renewable-driven and delocalized electrochemical process complementary to HB for NH3 production could be a key solution for our society that is facing climate change crisis and is demographically growing.
The Li mediated (Li-m) pathway represents the most promising solution: thanks to the unique reducing power of this alkali metal, electrochemical cell with Li salt in aprotic environment achieves the highest Faradic efficiency (FE) in the N2 reduction reaction (NRR) research field. Different systems have been evaluated in literature for Li-m NRR, both in a continuous process in presence of a proton donor as ethanol and in a step-by-step system, to conduct Li nitridation in absence of H+ and avoid the competitive hydrogen evolution reaction (HER).
In comparison with Li-m NRR continuous systems, the step-by-step technology could alternate H2O presence, as proton donor, with the electrochemical reaction. The system degradation, the proton donor consumption and HER could be avoided. Moreover, the Li-N2 reaction in a completely aprotic environment could maximize Li exploitation. This technology could enhance scalability, since the Li reduction, essential for its recirculation, is the more energy requiring step.
The promising Li-N2 cells have been recently tested both for ammonia production and as energy storage devices, in similarity with metallic Li-gaseous batteries (e.g. Li-O2 devices); even if this technology is still in its infancy, a proof-of-concept of NH3 formation has been verified and our laboratory is currently addressing this challenge within the SuN2rise project
The amoebal MAP kinase response to Legionella pneumophila is regulated by DupA
Full text linkThe amoeba Dictyostelium discoideum can support replication of Legionella pneumophila. Here we identify the dupA gene, encoding a putative tyrosine kinase/dual-specificity phosphatase, in a screen for D. discoideum mutants altered in allowing L. pneumophila intracellular replication. Inactivation of dupA resulted in depressed L. pneumophila growth and sustained hyperphosphorylation of the amoebal MAP kinase ERK1, consistent with loss of a phosphatase activity. Bacterial challenge of wild-type amoebae induced dupA expression and resulted in transiently increased ERK1 phosphorylation, suggesting that dupA and ERK1 are part of a response to bacteria. Indeed, over 500 of the genes misregulated in the dupA(-) mutant were regulated in response to L. pneumophila infection, including some thought to have immune-like functions. MAP kinase phosphatases are known to be highly upregulated in macrophages challenged with L. pneumophila. Thus, DupA may regulate a MAP kinase response to bacteria that is conserved from amoebae to mammals
Lasioseius paraconfusus Li, Yang & Li 2000
No full textLasioseius paraconfusus Li , Yang & Li, 2000 Lasioseius paraconfusus Li, Yang & Li, 2000: 41. Lasioseius paraconfusus.— Zhang & Fan, 2010: 283. TYPE DEPOSITORY: Research Institute of Endemic Disease Control, Qinghai, China. TYPE LOCALITY AND HABITAT: Huangzhong, Qinghai, China, in surface soil under haystack.Published as part of De Moraes, Gilberto J., Britto, Erika P. J., Mineiro, Jefferson L. De C. & Halliday, Bruce, 2016, Catalogue of the mite families Ascidae Voigts & Oudemans, Blattisociidae Garman and Melicharidae Hirschmann (Acari: Mesostigmata), pp. 1-299 in Zootaxa 4112 (1) on page 179, DOI: 10.11646/zootaxa.4112.1.1, http://zenodo.org/record/39947
The cosmological Li-7 problem from a nuclear physics perspective
No full textThe primordial abundance of Li-7 as predicted by Big Bang Nucleosynthesis (BBN) is more than a factor 2 larger than what has been observed in metal-poor halo stars. Herein, we analyze the possibility that this discrepancy originates from incorrect assumptions about the nuclear reaction cross sections relevant for BBN. To do this, we introduce an efficient method to calculate the changes in the Li-7 abundance produced by arbitrary (temperature dependent) modifications of the nuclear reaction rates. Then, considering that Li-7 is mainly produced from Be-7 via the electron capture process Be-7+e(-) -> Li-7+nu(e), we assess the impact of the various channels of Be-7 destruction. Differently from previous analysis, we consider the role of unknown resonances by using a complete formalism which takes into account the effect of Coulomb and centrifugal barrier penetration and that does not rely on the use of the narrow-resonance approximation. As a result of this, the possibility of a nuclear physics solution to the Li-7 problem is significantly suppressed. Given the present experimental and theoretical constraints, it is unlikely that the Be-7 + n destruction rate is underestimated by the 2.5 factor required to solve the problem. We exclude, moreover, that resonant destruction in the channels Be-7+t and Be-7+He-3 can explain the Li-7 puzzle. New unknown resonances in Be-7+d and Be-7+alpha could potentially produce significant effects. Recent experimental results have ruled out such a possibility for Be-7 + d. On the other hand, for the Be-7 + alpha channel very favorable conditions are required. The possible existence of a partially suitable resonant level in C-11 is studied in the framework of a coupled-channel model and the possibility of a direct measurement is considered
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