In the crown-ether complex, the metal ion fits into the cavity of the crown ether and is solvated by the oxygen atoms. The exterior of the complex is nonpolar, masked by the alkyl groups of the crown ether.
Arrow Alerts. Location-enabled apps and services track your iPhone by periodically querying it for location-based information. They may do this while being used or running in the background on your device. A little arrow appears on the iPhone's upper-right corner to advise you when data is shared. Arrows also appear within the Location Services settings screens to indicate when and what kinds of information was shared with whom.
Traditional target arrow (top) and replica medieval arrow. Modern arrow with plastic fletchings and nock. An arrow is a fin-stabilized projectile that is shot with a bow, and usually consists of a long straight shaft with a weighty and usually pointed arrowhead attached to the front end, with fletchings and a nock at the rear end. The use of bows and arrows by humans predates recorded history and is common to most cultures.