A method of switching refrigerant flow between a path to a freezer evaporator in a freezer compartment and a path to a fresh food evaporator in a fresh food compartment of a refrigerator includes providing a three-way valve with at least three operational positions in flow communication with the path to the fresh food evaporator and the path to the freezer evaporator. For example, an uncross-linked resin may be provided in particulate form, agglomerated, and compressed into a mass of a desired shape with a desired diameter, and subsequently cross-linked. A handle may be provided on the sheath. In some embodiments, the metal structure may include a first end region, a second end region, and an intermediate region. Methods for using such constructs in modulating the transcription of DNA sequences of interest are also disclosed, together with transgenic plants comprising such constructs.