Understanding human organ formation is a scientific challenge with far-reaching medical implications1,2. Three-dimensional stem-cell cultures have provided insights into human cell differentiation3,4. However, current approaches use scaffold-free stem-cell aggregates, which develop non-reproducible tissue shapes and variable cell-fate patterns. This limits their capacity to recapitulate organ formation. Here we present a chip-based culture system that enables self-organization of micropatterned stem cells into precise three-dimensional cell-fate patterns and organ shapes.

The most essential characteristic of any fluid is the velocity field, and this is particularly true for macroscopic quantum fluids1. Although rapid advances2–7 have occurred in quantum fluid velocity field imaging8, the velocity field of a charged superfluid—a superconductor—has never been visualized. Here we use superconducting-tip scanning tunnelling microscopy9–11 to image the electron-pair density and velocity fields of the flowing electron-pair fluid in superconducting NbSe2.

Based on work by Dubochet and others in the 1980s and 1990s, samples for single-particle cryo-electron microscopy (cryo-EM) have been vitrified using ethane, propane or ethane/propane mixtures. These liquid cryogens have a large difference between their melting and boiling temperatures and so can absorb substantial heat without formation of an insulating vapor layer adjacent to a cooling sample.

Excitonic insulators (EIs) arise from the formation of bound electron–hole pairs (excitons)1,2 in semiconductors and provide a solid-state platform for quantum many-boson physics3–8. Strong exciton–exciton repulsion is expected to stabilize condensed superfluid and crystalline phases by suppressing both density and phase fluctuations8–11. Although spectroscopic signatures of EIs have been reported6,12–14, conclusive evidence for strongly correlated EI states has remained elusive.

Ferromagnetism in two-dimensional materials presents a promising platform for the development of ultrathin spintronic devices with advanced functionalities. Recently discovered ferromagnetic van der Waals crystals such as CrI3, readily isolated two-dimensional crystals, are highly tunable through external fields or structural modifications. However, there remains a challenge because of material instability under air exposure. Here, we report the observation of an air-stable and layer-dependent ferromagnetic (FM) van der Waals crystal, CrPS4, using magneto-optic Kerr effect microscopy.

We use quantum kinetic theory to calculate the thermoelectric transport properties of the two-dimensional single-band Fermi-Hubbard model in the weak coupling limit. For generic filling, we find that the high-temperature limiting behaviors of the electrical (∼T) and thermal (∼T2) resistivities persist down to temperatures of order the hopping matrix element T∼t, almost an order of magnitude below the bandwidth. At half filling, perfect nesting leads to anomalous low-temperature scattering and nearly T-linear electrical resistivity at all temperatures.

An unidentified quantum fluid designated the pseudogap (PG) phase is produced by electron-density depletion in the CuO2 antiferromagnetic insulator. Current theories suggest that the PG phase may be a pair density wave (PDW) state characterized by a spatially modulating density of electron pairs. Such a state should exhibit a periodically modulating energy gap Δ P(r) in real-space, and a characteristic quasiparticle scattering interference (QPI) signature Λ P(q) in wavevector space.

Echoing classical physics, quantum electrodynamics predicts the release of a spectral continuum of electromagnetic radiation upon the sudden acceleration of charged particles in quantum matter. Despite apparent theoretical success in describing sister nuclear processes, known as internal bremsstrahlung, following nuclear beta decay and capture, the situation of the photoejection of an electron from an inner shell of an atom, intra-atomic bremsstrahlung (IAB), is far from settled.

Posttraumatic osteoarthritis (PTOA) is typically initiated by momentary supraphysiologic shear and compressive forces delivered to articular cartilage during acute joint injury and develops through subsequent degradation of cartilage matrix components and tissue remodeling. PTOA affects 12% of the population who experience osteoarthritis and is attributed to over $3 billion dollars annually in healthcare costs. It is currently unknown whether articulation of the joint post-injury helps tissue healing or exacerbates cellular dysfunction and eventual death.

Van der Waals moiré materials have emerged as a highly controllable platform to study electronic correlation phenomena1–17. Robust correlated insulating states have recently been discovered at both integer and fractional filling factors of semiconductor moiré systems10–17. In this study we explored the thermodynamic properties of these states by measuring the gate capacitance of MoSe2/WS2 moiré superlattices. We observed a series of incompressible states for filling factors 0–8 and anomalously large capacitance in the intervening compressible regions.