This invention provides a clock switching circuit that can switch clocks without causing a hazard or a distortion of a duty ratio of the clocks. The conductive heating elements may comprise flexible metal elements such as those used in an electric heating blanket and conduct throughout the jacket the electricity generated by the battery. The disclosure can improve the channel estimation quality of the CSI-RS. The special tags may be configured to be interpreted into SQL in order to communicate with an SQL compliant database, or the special tags may be configured to be interpreted to any other database language. Such methods include heating carbon nanotubes in a solvent in the absence of externally applied energy, to obtain an adduct that includes the solvent moiety bound to the carbon nanotube.