Theexplorer

MESOSCOPIC PHYSICS

A double edge
Jelena Stajic
Quasiparticles that reside in two-dimensional solids can display exotic quantum statistics—they do not behave as either fermions or bosons. Additionally, they carry a charge that is a fraction of an electron’s charge. Recently, these fractional quantum statistics were seen experimentally in interferometric and quasiparticle collider measurements in fractional quantum Hall (FQH) systems. Such experiments become more complex if more than one FQH edge state is present. Nakamura et al. studied a state formed at filling factor 2/5, which is predicted to have two edge states. The researchers’ conductance measurements in a Fabry-Pérot interferometer confirmed that the outer edge of this state is similar to that of the simpler 1/3 filling state; the inner edge state was found to have a fifth of the electron’s charge and to obey fractional statistics of the kind predicted by theory.

Phys. Rev. X (2023) 10.1103/PhysRevX.13.041012

Wonder Molecule - Pseudouridine

In recent years, pseudouridine proved to be a key molecule in the development of mRNA-based COVID-19 vaccines. Pseudouridine is a ribonucleoside and an isomer of the more frequently encountered uridine. The two differ by the location of the bond that connects their uracil and ribofuranose rings. Both are common components of RNA, but not DNA.

In 2005, Katalin Karikó at the University of Szeged (Hungary), Drew Weissman at the University of Pennsylvania (Philadelphia), and colleagues, in their attempts to use RNA to produce vaccines that could quickly be adapted to specific diseases, found that converting uridine to pseudouridine reduced the inflammatory response of mRNA while maintaining the immune response. Karikó, Weissman, et al. later showed that the switch to pseudouridine produced more stable RNA constructs and better protein yields.

Karikó and Weissman’s findings paid off big time when the necessity arose to produce COVID-19 vaccines in a hurry. For their groundbreaking work, they were awarded the 2023 Nobel Prize in Physiology or Medicine.