نتایج جستجو برای: chiral
تعداد نتایج: 37423 فیلتر نتایج به سال:
Chirality is ubiquitous in biology, including in biomineralization, where it is found in many hardened structures of invertebrate marine and terrestrial organisms (for example, spiralling gastropod shells). Here we show that chiral, hierarchically organized architectures for calcium carbonate (vaterite) can be controlled simply by adding chiral acidic amino acids (Asp and Glu). Chiral, vaterite...
Chiral materials are not invariant to inversions: there is a distinction between rightand left-handed material. Material properties such as piezoelectricity and pyroelectricity, represented by tensors of odd rank, can only occur in chiral materials. Chiral e!ects in elasticity cannot be expressed within classical elasticity since the modulus tensor, which is fourth rank, is unchanged under an i...
Nuclear magnetic resonance (NMR) is a powerful tool for the elucidation of chemical structure and chiral recognition. In the last decade, the number of probes, media, and experiments to analyze chiral environments has rapidly increased. The evaluation of chiral molecules and systems has become a routine task in almost all NMR laboratories, allowing for the determination of molecular connectivit...
The rôle of a chiral U(1) phase in the quark mass in QCD is analysed from first principles. In operator formulation, there is a parity symmetry and the phase can be removed by a change in the representation of the Dirac γ matrices. Moreover, these properties are also realized in a Pauli–Villars regularized version of the theory. In the functional integral scenario, attempts to remove the chiral...
A soluble and stable one-handed helical poly(substituted phenylacetylene) without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer followed by two-step polymer reactions in membrane state: (1) removing the chiral groups (desubstitution); and (2) introduction of achiral long alkyl groups at the same position as the...
A thermal [2 + 2] cycloaddition reaction of allene-ynes has been used to transform chiral non-racemic allenyl oxindoles into chiral non-racemic spirooxindoles containing an alkylidene cyclobutene moiety. The enantiomeric excesses were determined by chiral lanthanide shift NMR analysis and the transfer of chiral information from the allene to the spirooxindole was found to be greater than 95%.
I argue that in certain chiral gauge theories composite scalars associated with chiral symmetry breaking can be light (i.e. lighter than naive scaling from QCD would suggest) without any fine-tuning. These scalars will be even lighter in chiral gauge theories that produce chiral symmetry breaking without confinement. I construct a model which demonstrates this last possibility.
An abstract polytope is chiral if its automorphism group has two orbits on the flags, such that adjacent flags belong to distinct orbits. There are still few examples of chiral polytopes, and few constructions that can create chiral polytopes with specified properties. In this paper, we show how to build self-dual chiral polytopes using the mixing construction for polytopes.
Twisted atomic bilayers are emerging platforms for manipulating chiral light-matter interaction at the extreme nanoscale, due to their inherent magnetoelectric responses induced by finite twist angle and quantum interlayer coupling between layers. Recent studies have reported direct correspondence twisted metasurfaces, which features a surface conductivity, in addition electric magnetic conduct...
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