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31.
Benjamin Arras Ehsan Azmoodeh Guillaume Poly Yvik Swan 《Stochastic Processes and their Applications》2019,129(7):2341-2375
We provide a bound on a distance between finitely supported elements and general elements of the unit sphere of . We use this bound to estimate the Wasserstein-2 distance between random variables represented by linear combinations of independent random variables. Our results are expressed in terms of a discrepancy measure related to Nourdin–Peccati’s Malliavin–Stein method. The main application is towards the computation of quantitative rates of convergence to elements of the second Wiener chaos. In particular, we explicit these rates for non-central asymptotic of sequences of quadratic forms and the behavior of the generalized Rosenblatt process at extreme critical exponent. 相似文献
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Denis D. Borisov Grigory R. Chermashentsev Roman A. Novikov Yury V. Tomilov 《Tetrahedron letters》2019,60(10):746-750
New “four-component” self-assembly of polyaromatic thiophene structures based on styrylmalonates and 5-phenylthiophene-2-carbaldehyde has been developed. This process is promoted by GaCl3 and involves two [2?+?3]-annulation steps on the CHO-groups and para-substitution into one Ph-ring. The main feature of discovered process is a high diastereoselectivity with a significant increase in molecular complexity. The resulting polyaromatic structures containing two thiophene moieties in each structure have intense color and strong absorption in a near UV spectral region with absorption maxima in the range of 257–360?nm. 相似文献
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36.
Eva Rivera‐Chao Maider Mitxelena Jesús A. Varela Martín Faans‐Mastral 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18398-18402
The first copper‐catalyzed enantioselective allylboration of alkynes is reported. The method employs a multitasking chiral NHC‐Cu catalyst and provides access to densely functionalized molecules from simple starting materials with excellent levels of chemo‐, regio‐, and enantioselectivity. These multifunctional products display highly versatile reactivity as shown by the synthesis of a variety of non‐racemic molecular scaffolds. DFT calculations were conducted to gain insight into the high selectivity levels of this catalytic process. 相似文献
37.
Fan Yang Shuaishuai Zhang Jingpeng Song Qing Du Guixiang Li Nadezda V. Tarakina Markus Antonietti 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):18989-18992
Artificial humic acids (A‐HA) made from biomass in a hydrothermal process turn otherwise highly insoluble phosphates (e.g. iron phosphate as a model) into highly available phosphorus, which contributes to the fertility of soils and the coupled plant growth. A detailed electron microscopy study revealed etching of the primary iron phosphate crystals by the ‐COOH and phenolic groups of humic acids, but also illustrated the importance of the redox properties of humic matter on the nanoscale. The combined effects result in the formation of then bioavailable phosphate nanoparticles stabilized by humic matter. Typical agricultural chemical tests indicate that the content of total P and directly plant‐available P improved largely. Comparative pot planting experiments before and after treatment of phosphates with A‐HA demonstrate significantly enhanced plant growth, as quantified in higher aboveground and belowground plant biomass. 相似文献
38.
Hans Jagusch Markus Werner Oliver Werz Georg Pohnert 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17805-17809
Arachidonic‐acid‐derived prostaglandins (PGs), specifically PGE2, play a central role in inflammation and numerous immunological reactions. The enzymes of PGE2 biosynthesis are important pharmacological targets for anti‐inflammatory drugs. Besides mammals, certain edible marine algae possess a comprehensive repertoire of bioactive arachidonic‐acid‐derived oxylipins including PGs that may account for food poisoning. Described here is the analysis of PGE2 biosynthesis in the red macroalga Gracilaria vermiculophylla that led to the identification of 15‐hydroperoxy‐PGE2, a novel precursor of PGE2 and 15‐keto‐PGE2. Interestingly, this novel precursor is also produced in human macrophages where it represents a key metabolite in an alternative biosynthetic PGE2 pathway in addition to the well‐established arachidonic acid‐PGG2‐PGH2‐PGE2 route. This alternative pathway of mammalian PGE2 biosynthesis may open novel opportunities to intervene with inflammation‐related diseases. 相似文献
39.
Fan‐Li Zhang Jun Yi Wei Peng Petar M. Radjenovic Hua Zhang Zhong‐Qun Tian Jian‐Feng Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(35):12261-12265
The fundamental understanding of the subtle interactions between molecules and plasmons is of great significance for the development of plasmon‐enhanced spectroscopy (PES) techniques with ultrahigh sensitivity. However, this information has been elusive due to the complex mechanisms and difficulty in reliably constructing and precisely controlling interactions in well‐defined plasmonic systems. Herein, the interactions in plasmonic nanocavities of film‐coupled metallic nanocubes (NCs) are investigated. Through engineering the spacer layer, molecule–plasmon interactions were precisely controlled and resolved within 2 nm. Efficient energy exchange interactions between the NCs and the surface within the 1–2 nm range are demonstrated. Additionally, optical dressed molecular excited states with a huge Lamb shift of ≈7 meV at the single‐molecule (SM) level were observed. This work provides a basis for understanding the underlying molecule–plasmon interaction, paving the way for fully manipulating light–matter interactions at the nanoscale. 相似文献
40.
Dake Hu Tianqi Zhao Xiaofan Ping Husong Zheng Lei Xing Xiaozhi Liu Jingying Zheng Lifei Sun Lin Gu Chenggang Tao Dong Wang Liying Jiao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(21):7051-7055
Two‐dimensional (2D) PtSe2 shows the most prominent layer‐dependent electrical properties among various 2D materials and high catalytic activity for hydrogen evolution reaction (HER), and therefore, it is an ideal material for exploring the structure–activity correlations in 2D systems. Here, starting with the synthesis of single‐crystalline 2D PtSe2 with a controlled number of layers and probing the HER catalytic activity of individual flakes in micro electrochemical cells, we investigated the layer‐dependent HER catalytic activity of 2D PtSe2 from both theoretical and experimental perspectives. We clearly demonstrated how the number of layers affects the number of active sites, the electronic structures, and electrical properties of 2D PtSe2 flakes and thus alters their catalytic performance for HER. Our results also highlight the importance of efficient electron transfer in achieving optimum activity for ultrathin electrocatalysts. Our studies greatly enrich our understanding of the structure–activity correlations for 2D catalysts and provide new insight for the design and synthesis of ultrathin catalysts with high activity. 相似文献