Abstract: Exemplary air breathing plasma jet engine and method of operation that can be used in electrically powered aircraft and spacecraft as a hybrid between a turbo jet engine and a ramjet or supersonic sonic ramjet (SCRAMJET) engine. The air breathing plasma jet engine includes a compression stage that is configured to compress and slow down incoming air. The compressor can be driven by a high RPM electric motor. The compression stage generates compressed and heated air flow that is passed to a plasma chamber that is configured to add heat to the compressed and heated air flow. The heat are converted to an impulse, e.g., using a converging-diverging (De Laval) nozzle. The system is beneficially configured to reuse the heat byproduct generated in the compression stage.

Abstract: Disclosed herein are cryogenic wires and methods of making and use thereof. For example, disclosed herein are cryogenic wires comprising a conductor having a mass density of 5000 kg/m3 or less; and a cladding material disposed around the conductor, the cladding material comprising a ductile and malleable metal, wherein the conductor comprises lithium, beryllium, calcium, sodium, magnesium, titanium, or a combination thereof. In some examples, the conductor comprises lithium or an alloy thereof, beryllium or an alloy thereof, calcium or an alloy thereof, sodium or an alloy thereof, magnesium or an alloy thereof, titanium or an alloy thereof, or a combination thereof.

Abstract: Disclosed herein include methods, compositions, and kits suitable for use in calcium imaging. There are provided, in some embodiments, Ca2+-sensing GvpC proteins. Disclosed herein include Ca2+-sensing gas vesicles (GVs) comprising Ca2+-sensing GvpC proteins. In some embodiments, the Ca2+-sensing GvpC protein is capable of undergoing a first allosteric conformational change upon the Ca2+-binding domain binding Ca2+ that causes the Ca2+-sensing GV to change from a GV stiff state to a GV soft state. One or more of the mechanical, acoustic, surface, and magnetic properties of a Ca2+-sensing GV can differ between the GV soft state and the GV stiff state.

Abstract: Provided herein are engineered protease sensitive gas vesicles and related engineered protease genetically GvpC constructs, vectors, gas vesicles gene clusters, genetic circuits, cells, compositions, methods and systems, which in several embodiments can be used together with contrast-enhanced imaging technique, to detect and report protease activity and related biological events in an imaging target site.