54 research outputs found

    Cis-Selective and Highly Enantioselective Hydrogenation of 2,3,4-Trisubstituted Quinolines

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    A highly enantioselective <i>cis</i>-hydrogenation of 2,3,4-trisubstituted quinolines has been realized for the first time using chiral borane catalysts generated in situ from chiral dienes. A variety of tetrahydroquinoline derivatives containing three contiguous stereogenic centers were obtained in 76–99% yields with 82–99% ee’s

    Enantioselective Metal-Free Hydrogenations of Disubstituted Quinolines

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    A metal-free hydrogenation of 2,4-disubstituted quinolines was realized for the first time using chiral diene derived borane catalysts to furnish the corresponding tetrahydroquinolines in 75–98% yields with 95/5−99/1 dr’s and 86–98% ee’s. This catalytic system was also effective for 2,3-disubstituted quinolines to give moderate to good ee’s

    Visualization 1: Self-decelerating Airy–elegant-Hermite–Gaussian and Airy–helical-elegant-Hermite–Gaussian wave packets

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    An animation of the propagation shown in Fig. 4. Originally published in JOSA B on 01 November 2016 (josab-33-11-2204

    Compositions, Structures, and Catalytic Activities of CeO<sub>2</sub>@Cu<sub>2</sub>O Nanocomposites Prepared by the Template-Assisted Method

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    CeO<sub>2</sub>@Cu<sub>2</sub>O nanocomposites were prepared from Cu<sub>2</sub>O cubes and octahedra by the template-assisted method involving the liquid (Ce­(IV))–solid (Cu<sub>2</sub>O) interfacial reaction. Their compositions, structures, and catalytic activities in CO oxidation were studied in detail. Under the same reaction conditions, CeO<sub>2</sub>@Cu<sub>2</sub>O nanocomposites prepared from cubic and octahedral Cu<sub>2</sub>O templates exhibit different compositions and structures. With an increasing amount of Ce­(IV) reactant, a smooth CeO<sub>2</sub>–CuO<sub><i>x</i></sub> shell develops on the surface of Cu<sub>2</sub>O cubes and eventually void cubic core/multishell Cu<sub>2</sub>O/CeO<sub>2</sub>–CuO<sub><i>x</i></sub> nanocomposites form; however, a rough CeO<sub>2</sub>–CuO<sub><i>x</i></sub> shell develops on the surface of Cu<sub>2</sub>O octahedra, and eventually hollow octahedral CeO<sub>2</sub>–CuO<sub><i>x</i></sub> nanocages form. The formation of different compositions and structures of CeO<sub>2</sub>@Cu<sub>2</sub>O nanocomposites was correlated with the different exposed crystal planes and surface reactivities of Cu<sub>2</sub>O cubes and octahedra. The catalytic activity of CeO<sub>2</sub>@Cu<sub>2</sub>O nanocomposites in CO oxidation depends on their compositions and structures. The most active CeO<sub>2</sub>@Cu<sub>2</sub>O nanocomposites become active at 70 °C and achieve a 100% CO conversion at 170 °C. These results broaden the versatility of Cu<sub>2</sub>O nanocrystals as the sacrificial template for the fabrication of novel nanocomposites with core/shell and hollow nanostructures and exemplify the morphology effect of Cu<sub>2</sub>O nanocrystals in liquid–solid interfacial reactions with respect to the composition, structure, and properties of nanocomposites prepared by the template-assisted method

    Simulation Studies on Robust Contacts in V<sub>2</sub>CT<sub>2</sub>/MoSi<sub>2</sub>N<sub>4</sub> (TO, F, OH) van der Waals Heterojunction Nanostructures: Implications for Optoelectronic Devices

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    Research on metal electrode–semiconductor contacts has primarily focused on adjusting the Schottky barrier height (SBH), with little attention paid to the stability of electronic properties upon contact. Herein, we comprehensively investigate the sensitivity of contact properties to the external electric field (ΔE), out-plane strain (Δd), and in-plane biaxial strain (Δδ) taking the V2C(T2)/MoSi2N4 (TO, OH, F) van der Waals heterojunction (vdWH) as an example. Our findings suggest that surface functionalization (-T termination) is a powerful tool for controlling contact characteristics. Importantly, when ΔE0.3 V/nm, Δd = −0.1 Å, and Δδ < 0%, the intrinsic contact properties of V2C/MoSi2N4 may be changed. However, V2CT2/MoSi2N4 can maintain the intrinsic contact properties over a wider range of ΔE, Δd, and Δδ. Furthermore, we design a p–i–n optoelectronic transistor (V2CO2/MoSi2N4/V2CO2H2), which has excellent tunneling probability (100%), photocurrent density (11.336 A/m2), responsivity (0.322 AW–1), and external quantum efficiency (71.061%). Our work not only serves as a reference for eliminating the error of information transmission and the degradation of device performance caused by contact property sensitivity to electric field and strain but also provides theoretical guidance for the experimental design of high-performance MoSi2N4-based optoelectronic devices

    Cyclization of Alkyne–Azide with Isonitrile/CO via Self-Relay Rhodium Catalysis

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    A self-relay rhodium­(I)-catalyzed cyclization of alkyne–azides with two σ-donor/π-acceptor ligands (isonitriles and CO) to form sequentially multiple-fused heterocycle systems via tandem nitrene transformation and aza-Pauson–Khand cyclization has been developed. In this approach, an intriguing chemoselective insertion process of isonitriles superior to CO was observed. This reaction provides an alternative strategy to synthesize functionalized pyrrolo­[2,3-<i>b</i>]­indole scaffolds

    Diagrammatic presentation of the experimental design.

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    <p>The circular pollen donor N12-1 plot with radius 5m was planted at the center of experiment field. Pollen recipient dwarf male-sterile wheat (DMSW) was grown at eight compass directions. The radius of concentric circle of the recipient DMSW was 50 m.</p

    One-way ANOVA for the transgene flow frequency in different compass sectors.

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    <p>One-way ANOVA for the transgene flow frequency in different compass sectors.</p

    The exponential decay models for pollen and gene flow of transgenic wheat and the corresponding determination coefficient (R<sup>2</sup>) in eight compass sectors.

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    <p>The exponential decay models for pollen and gene flow of transgenic wheat and the corresponding determination coefficient (R<sup>2</sup>) in eight compass sectors.</p

    Additional file 1: of The Antarctic sea ice alga Chlamydomonas sp. ICE-L provides insights into adaptive patterns of chloroplast evolution

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    Table S1. Results of the basic (M0) model test of individual genes and the concatenated data. Table S2. Results of the correct P-value of LRT in branch-model test. Table S3. Results of site-model test to each gene-specific and the concatenated data. Table S4. Results of branch-site model analyses using the concatenated data. Table S5. Results of convergence test between Chlamydomonas sp. ICE-L and Dunaliella salina. Figure S1. Results of divergence time analyses. The estimated divergence times were showed with 95% confidence intervals. Figure S2. The dN/dS estimates for the concatenated data using the M8 random-site model. The y-axis shows the BEB posterior mean estimate of dN/dS for each site. (DOCX 341 kb
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