Abstract: The present invention provides a method of preparing directly a desired nano-structure of oxide without electrolyzing the target oxide, a nano-structure having structural resistance and various useful uses of the nano-structure. Into a solution containing a fluoride complex ion comprising metal element of the target oxide in which the metal is at least one selected from the group consisting of transition metal elements, group IA elements, group IIA elements, group IIIB elements, group IVB elements, group VB elements and group VIB elements, a template having nano-structure made from oxide is immersed, and the reaction condition is adjusted to substitute oxide of the template with the target oxide.

Abstract: An elastic wave is applied to an object under the ground, so that an elastic wave which varies in accordance with the material and shape of the object under the ground is detected and the detected elastic wave is collated with characteristic data such as elastic wave data, or the like, of various objects registered in advance to thereby identify/discriminate the object under the ground. A vibration generating probe and a vibration receiving probe, or, alternatively, a vibration generating and receiving probe is put into the ground so as to come in contact with an object under the ground. Then, the vibration generating probe or vibration generating and receiving probe is hammered to generate an elastic wave. At least one of one longitudinal wave and two transverse waves of the elastic wave which has propagated to the object under the ground is received by the vibration receiving probe or vibration generating and receiving probe.