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641.
Victor I. Afonso Gonzalo J. Olmo Emanuele Orazi Diego Rubiera-Garcia 《The European Physical Journal C - Particles and Fields》2018,78(10):866
We show that families of nonlinear gravity theories formulated in a metric-affine approach and coupled to a nonlinear theory of electrodynamics can be mapped into general relativity (GR) coupled to another nonlinear theory of electrodynamics. This allows to generate solutions of the former from those of the latter using purely algebraic transformations. This correspondence is explicitly illustrated with the Eddington-inspired Born–Infeld theory of gravity, for which we consider a family of nonlinear electrodynamics and show that, under the map, preserve their algebraic structure. For the particular case of Maxwell electrodynamics coupled to Born–Infeld gravity we find, via this correspondence, a Born–Infeld-type nonlinear electrodynamics on the GR side. Solving the spherically symmetric electrovacuum case for the latter, we show how the map provides directly the right solutions for the former. This procedure opens a new door to explore astrophysical and cosmological scenarios in nonlinear gravity theories by exploiting the full power of the analytical and numerical methods developed within the framework of GR. 相似文献
642.
Rebeca Marcilla Estibalitz Ochoteco Cristina Pozo‐Gonzalo Hans Grande Jose A. Pomposo David Mecerreyes 《Macromolecular rapid communications》2005,26(14):1122-1126
Summary: Polypyrrole (PPy), polyaniline (PANI), and poly(ethylenedioxythiophene) (PEDOT) aqueous dispersions were prepared by polymerizing the corresponding monomer in the presence of a polymeric ionic liquid (PIL), poly(1‐vinyl‐3‐ethylimidazolium bromide). By addition of bispentafluoroethanesulfonimide lithium salt, the PIL stabilizer becomes hydrophobic and precipitates in water and traps the conducting polymer microparticles inside. The dispersion of the recovered powders in organic solvents leads to organic conducting dispersions. After casting the organic dispersions, hydrophobic films with electrical conductivity values as high as 0.1 S · cm−1 were obtained.
643.
Dr. Gonzalo García-Espejo Dr. Konstantis F. Konidaris Dr. Pietro Anzini Prof. Stefano Brenna Dr. Antonietta Guagliardi Prof. Norberto Masciocchi 《欧洲无机化学杂志》2023,26(23):e202300282
The discovery of new 3D perovskites and their 2D and 1D analogues continues to attract the interest of the scientific community and therefore the understanding of their structural, optical, and physicochemical properties is of fundamental importance. Here, we report the one-pot synthesis and the full characterization of 1D and 2D lead halide polycrystalline solids containing the rather rigid 1,4-xylylenediammonium (pXDA) organic cation as spacer. We isolated 2D Dion-Jacobson (DJ) perovskites, namely (pXDA)PbX4 (X=Cl, Br) and the mixed halide (pXDA)Pb(Br1–xIx)4 species (all based on 2D monolayers of corner-sharing lead halide octahedra), and, for iodine, the (pXDA)Pb2I6 . 2H2O phase, which contains 1D ribbons. The latter species can be reversibly dehydrated by gentle heating, forming the isomorphous (pXDA)Pb2I6. crystal phase. These species, some of which have recently been studied in the frame of broad light emitters and for photovoltaic applications, have been characterized by variable-temperature X-ray diffraction methods, shedding light onto their anisotropic thermal responses, of utmost importance for day-night cycling in functional devices. Spin-coated thin films were also prepared and studied by means of synchrotron radiation grazing incidence X-ray diffraction, SEM imaging and fluorescence spectroscopy experiments. 相似文献
644.
Protoglobin-Catalyzed Formation of cis-Trifluoromethyl-Substituted Cyclopropanes by Carbene Transfer
Lucas Schaus Dr. Anuvab Das Dr. Anders M. Knight Dr. Gonzalo Jimenez-Osés Prof. Dr. K. N. Houk Dr. Marc Garcia-Borràs Prof. Dr. Frances H. Arnold Prof. Dr. Xiongyi Huang 《Angewandte Chemie (International ed. in English)》2023,62(4):e202208936
Trifluoromethyl-substituted cyclopropanes (CF3-CPAs) constitute an important class of compounds for drug discovery. While several methods have been developed for synthesis of trans-CF3-CPAs, stereoselective production of corresponding cis-diastereomers remains a formidable challenge. We report a biocatalyst for diastereo- and enantio-selective synthesis of cis-CF3-CPAs with activity on a variety of alkenes. We found that an engineered protoglobin from Aeropyrnum pernix (ApePgb) can catalyze this unusual reaction at preparative scale with low-to-excellent yield (6–55 %) and enantioselectivity (17–99 % ee), depending on the substrate. Computational studies revealed that the steric environment in the active site of the protoglobin forced iron-carbenoid and substrates to adopt a pro-cis near-attack conformation. This work demonstrates the capability of enzyme catalysts to tackle challenging chemistry problems and provides a powerful means to expand the structural diversity of CF3-CPAs for drug discovery. 相似文献
645.