Significance: Although the laser refrigeration of bulk crystals has recently shown to cool below cryogenic temperatures (∼90 K) in vacuum, to date the laser refrigeration of physiological media has not been reported. In this work, a low-cost hydrothermal synthetic approach is used to prepare nanocrystals that are capable of locally refrigerating physiological buffers (PBS, DMEM) upon near-infrared illumination. Optical tweezers are used in tandem with cold Brownian motion analysis to observe the refrigeration of individual (Yb³⁺)-doped nanocrystals >10 °C below ambient conditions. The ability to optically generate local refrigeration fields around individual nanocrystals promises to enable precise optical temperature control within integrated electronic/photonic/microfluidic circuits, and also thermal modulation of basic biomolecular processes, including the dynamics of motor proteins.

We create defects for quantum technologies by using high temperatures and pressures to convert molecularly doped carbon to diamond.

Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel’s void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material reveal the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel.

Transition metal dichalcogenide (TMD) materials have recently demonstrated exceptional supercapacitor properties after conversion to a metallic phase, which increases the conductivity of the network. However, freestanding, exfoliated transition metal dichalcogenide films exhibit surface areas far below their theoretical maximum (1.2 %), can fail during electrochemical operation due to poor mechanical properties, and often require pyrophoric chemicals to process. On the other hand, pyrolyzed carbon aerogels exhibit extraordinary specific surface areas for double layer capacitance, high conductivity, and a strong mechanical network of covalent chemical bonds. In this paper, we demonstrate the scalable, rapid nanomanufacturing of TMD (MoS₂and WS₂) and carbon aerogel composites, favoring liquid-phase exfoliation to avoid pyrophoric chemicals. The aerogel matrix support enhances conductivity of the composite and the synthesis can complete in 30 min. We find that the addition of transition metal dichalcogenides does not impact the structure of the aerogel, which maintains a high specific surface area up to 620 m² g⁻¹with peak pore radii of 10 nm. While supercapacitor tests of the aerogels yield capacitances around 80 F g⁻¹at the lowest applied currents, the aerogels loaded with TMD’s exhibit volumetric capacitances up to 127% greater than the unloaded aerogels. In addition, the WS₂aerogels show excellent cycling stability with no capacitance loss over 2000 cycles, as well as markedly better rate capability and lower charge transfer resistance compared to their MoS₂-loaded counterparts. We hypothesize that these differences in performance stem from differences in contact resistance and in the favorability of ion adsorption on the chalcogenides.