Abstract: Data exchange section 104 has a step of determining whether or not pairs of the transmission selecting conditions and reception selecting conditions satisfy a standard for exchanging, through a determined pair, data between a transmission user who corresponds to a transmission selecting condition in the determined pair and a reception user who corresponds to a reception selecting condition in the determined pair. Data exchange system 100 exchanges data satisfying both the transmission selecting condition and the reception selecting condition in the determined pair between the transmission user and the reception user, respectively corresponding to the transmission selecting condition and the reception selecting condition in the determined pair.

Abstract: Data exchange section 104 has a step of determining whether or not pairs of the transmission selecting conditions and reception selecting conditions satisfy a standard for exchanging, through a determined pair, data between a transmission user who corresponds to a transmission selecting condition in the determined pair and a reception user who corresponds to a reception selecting condition in the determined pair. Data exchange system 100 exchanges data satisfying both the transmission selecting condition and the reception selecting condition in the determined pair between the transmission user and the reception user, respectively corresponding to the transmission selecting condition and the reception selecting condition in the determined pair.

Abstract: Data management security against leakage or loss of personal information is achieved by setting a division range for dividing personal information into identification information that enables a specific individual to be identified and attribute information that does not by itself enable a specific individual to be identified.

Abstract: A new compound represented by a composition formula Fe8O8 (OH)8-2x((SO4)a, (HPO4)b)x (a+b=x, 1?x?1.75, 0<a?1.658, 0.092?b?x) formed by adding a shwertmannite of a composition formula Fe8O8(OH)8-2x(SO4)x (1?x?1.75) to a phosphoric acid solution of a pH value of 2-9 thereby achieving a stabilization by an adsorption of phosphoric acid, shows a very firm stabilization under conditions of 0<a?1.253 and 0.497?b?x. The new compound has a high stability, can maintain a high adsorbing ability for arsenic and the like and a cleaning level for a necessary period or semi-permanently, and can adsorb arsenic and the like in polluted water or polluted soil.