Abstract: Provided are compositions that include an active agent conjugated to a polymer strand and a carrier. In some embodiments, the polymer strand includes a monomer or unit, optionally a nucleotide sequence, that is modifiable to record one or more environmental conditions and/or a path in a volume experienced by the composition or that encodes a map for such a path for comparison to an actually-experienced path. Also provided are apparatuses for testing and/or recording one or more environmental conditions and/or traveled paths experienced by the compositions, methods for chemical recording of environmental sequences experienced by the compositions, kits that include the compositions and at least one reagent required to perform chemical recording of an environmental sequence experienced by the compositions, chemical recording devices that employ the compositions, drug delivery particles that include the compositions, and formulations of the compositions.

Abstract: Provided are methods for targeted drug delivery via mechanisms that use a particle's internal estimate of its own location within the body to target drug release at points specified on the basis of off-line medical imaging In some embodiments, the method relate to delivery that is accomplished by tailoring a material's composition so that it releases drugs or a chemical marker or dye when exposed to a specific sequence of environmental conditions or some set of specific sequences of environmental conditions, but does not do so when exposed to other such sequences.

Abstract: Heat engines suitable for large-scale or micro-scale fabrication supply power from a power turbine. The power turbine is driven in part by an ejector in which a working fluid is utilized as a motive flow. Fuel utilized for combustion may also be utilized as a phase-changing working fluid and as the motive flow driving the ejector. Heat exchangers particularly suitable for micro-scale implementation are also disclosed.

Abstract: Methods for measuring environmental parameters using chemical recording are provided. In some embodiments, the methods include generating a polymer comprising an ordered series of chemical units, wherein the position and number of each chemical unit in the polymer is indicative of a reading of the environmental state variable at a given point in time. The presently disclosed subject matter also provides compositions that can be employed in and/or that employ the disclosed methods for recording environmental state variables.