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1.
We study maps from a 2‐surface into the standard 2‐sphere coupled with Born‐Infeld geometric electromagnetism through an Abelian gauge field. Such a formalism extends the classical harmonic map model, known as the σ‐model, governing the spin vector orientation in a ferromagnet allows us to obtain the coexistence of vortices and antivortices characterized by opposite, self‐excited, magnetic flux lines. We show that the Born‐Infeld free parameter may be used to achieve arbitrarily high local concentration of magnetic flux lines that the total minimum energy is an additive function of these quantized flux lines realized as the numbers of vortices antivortices. In the case where the underlying surface, or the domain, is compact, we obtain a necessary sufficient condition for the existence of a unique solution representing a prescribed distribution of vortices antivortices. In the case where the domain is the full plane, we prove the existence of a unique solution representing an arbitrary distribution of vortices and antivortices. Furthermore, we also consider the Einstein gravitation induced by these vortices, known as cosmic strings, establish the existence of a solution representing a prescribed distribution of cosmic strings cosmic antistrings under a necessary sufficient condition that makes the underlying surface a complete surface with respect to the induced gravitational metric. © 2003 Wiley Periodicals, Inc. 相似文献
2.
In this paper, we prove the existence of a unit‐charge energy minimizer in the two‐dimensional Skyrme model by the method of concentration‐compactness. © 2004 Wiley Periodicals, Inc. 相似文献
3.
Evelina Liarou Yisong Han Ana M. Sanchez Marc Walker David M. Haddleton 《Chemical science》2020,11(20):5257
Rapidly self-deoxygenating Cu-RDRP in aqueous media is investigated. The disproportionation of Cu(i)/Me6Tren in water towards Cu(ii) and highly reactive Cu(0) leads to O2-free reaction environments within the first seconds of the reaction, even when the reaction takes place in the open-air. By leveraging this significantly fast O2-reducing activity of the disproportionation reaction, a range of well-defined water-soluble polymers with narrow dispersity are attained in a few minutes or less. This methodology provides the ability to prepare block copolymers via sequential monomer addition with little evidence for chain termination over the lifetime of the polymerization and allows for the synthesis of star-shaped polymers with the use of multi-functional initiators. The mechanism of self-deoxygenation is elucidated with the use of various characterization tools, and the species that participate in the rapid oxygen consumption is identified and discussed in detail.The rapidly self-deoxygenating Cu-RDRP in aqueous media is investigated. 相似文献
4.
In the recently discovered (2+1)-dimensional relativistic Chern-Simons model, self-duality can be achieved when the Higgs potential density assumes a special form for which both the asymmetric and symmetric vacua are ground state solutions. This important feature may imply the coexistence of static topological and non-topological vortex-like solutions inR 2 but the latter have been rather elusive to a rigorous construction. Our main purpose in this paper is to prove the existence of non-topological radially symmetricN-vortex solutions in the self-dual Chern-Simons model. By a shooting method, we obtain a continuous family of gauge-distinctN-vortex solutions. Moreover, we are also able to classify all possible bare (or 0-vortex) solutions. 相似文献
5.
Saikat Banerjee Waqas Rasheed Ruixi Fan Dr. Apparao Draksharapu Dr. Williamson N. Oloo Prof. Dr. Yisong Guo Prof. Dr. Lawrence Que Jr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(41):9608-9613
The [FeIV(O)(Me3NTB)]2+ (Me3NTB=tris[(1-methyl-benzimidazol-2-yl)methyl]amine) complex 1 has been shown by Mössbauer spectroscopy to have an S=1 ground state at 4 K, but is proposed to become an S=2 trigonal-bipyramidal species at higher temperatures based on a DFT model to rationalize its very high C−H bond-cleavage reactivity. In this work, 1H NMR spectroscopy was used to determine that 1 does not have C3-symmetry in solution and is not an S=2 species. Our results show that 1 is unique among nonheme FeIV=O complexes in retaining its S=1 spin state and high reactivity at 193 K, providing evidence that S=1 FeIV=O complexes can be as reactive as their S=2 counterparts. This result emphasizes the need to identify factors besides the ground spin state of the FeIV=O center to rationalize nonheme oxoiron(IV) reactivity. 相似文献
6.
Tzu-Yu Chen Jinfeng Chen Yijie Tang Dr. Jiahai Zhou Dr. Yisong Guo Dr. Wei-chen Chang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(19):7437-7441
N-alkylisonitrile, a precursor to isonitrile-containing lipopeptides, is biosynthesized by decarboxylation-assisted -N≡C group (isonitrile) formation by using N-alkylglycine as the substrate. This reaction is catalyzed by iron(II) and 2-oxoglutarate (Fe/2OG) dependent enzymes. Distinct from typical oxygenation or halogenation reactions catalyzed by this class of enzymes, installation of the isonitrile group represents a novel reaction type for Fe/2OG enzymes that involves a four-electron oxidative process. Reported here is a plausible mechanism of three Fe/2OG enzymes, Sav607, ScoE and SfaA, which catalyze isonitrile formation. The X-ray structures of iron-loaded ScoE in complex with its substrate and the intermediate, along with biochemical and biophysical data reveal that -N≡C bond formation involves two cycles of Fe/2OG enzyme catalysis. The reaction starts with an FeIV-oxo-catalyzed hydroxylation. It is likely followed by decarboxylation-assisted desaturation to complete isonitrile installation. 相似文献
7.
8.
Tzu‐Yu Chen Jinfeng Chen Yijie Tang Jiahai Zhou Yisong Guo Wei‐chen Chang 《Angewandte Chemie (International ed. in English)》2020,59(19):7367-7371
N‐alkylisonitrile, a precursor to isonitrile‐containing lipopeptides, is biosynthesized by decarboxylation‐assisted ‐N≡C group (isonitrile) formation by using N‐alkylglycine as the substrate. This reaction is catalyzed by iron(II) and 2‐oxoglutarate (Fe/2OG) dependent enzymes. Distinct from typical oxygenation or halogenation reactions catalyzed by this class of enzymes, installation of the isonitrile group represents a novel reaction type for Fe/2OG enzymes that involves a four‐electron oxidative process. Reported here is a plausible mechanism of three Fe/2OG enzymes, Sav607, ScoE and SfaA, which catalyze isonitrile formation. The X‐ray structures of iron‐loaded ScoE in complex with its substrate and the intermediate, along with biochemical and biophysical data reveal that ‐N≡C bond formation involves two cycles of Fe/2OG enzyme catalysis. The reaction starts with an FeIV‐oxo‐catalyzed hydroxylation. It is likely followed by decarboxylation‐assisted desaturation to complete isonitrile installation. 相似文献
9.
Isonitrile group has been identified in many natural products.Due to the broad reactivity of N≡C triple bond,these natural products have valuable pharmaceutical potentials.This review summarizes the current biosynthetic pathways and the corresponding enzymes that are responsible for isonitrile-containing natural product generation.Based on the strategies utilized,two fundamentally distinctive approaches are discussed.In addition,recent progress in elucidating isonitrile group formation mechanisms is also presented. 相似文献
10.
Yisong Yang 《Letters in Mathematical Physics》1990,19(3):257-267
The main result of this note is a proof of a conjecture of Burzlaff, O'Sé and Tchrakian [1] concerning the existence of a certain kind of finite action solutions of the seven-dimensional generalized Yang-Mills-Higgs model derived from an eight-dimensional SO(8) Yang-Mills theory. 相似文献