Abstract: A link mechanism for an arm portion includes an arm portion, a non-rotating arm attachment portion, a variable-length rod, and a fixed-length rod. The arm portion holds a medical instrument. The arm portion is attached to the arm attachment portion to be rotatable about an arm rotational axis as a center. The variable-length rod includes an elastic member which biases an elastic force to bring about a recovery against a pressing force. One end of the variable-length rod is pivotably attached to the arm attachment portion and the other end of the variable-length rod is pivotably connected to one end of the fixed-length rod. The fixed-length rod has its other end attached to the arm portion to be movable about the arm rotational axis upon rotation of the arm portion.

Abstract: A nanoparticle includes a chain oligomer section having a hydrophilic group and fluoroalkyl groups respectively at its opposite terminals, a three-dimensional silica network section, and an organic chain having fluorine or silicon, and is represented by the following formula (2): where R? is independent H or independent alkyl group; X is the hydrophilic group and is selected from the group consisting of an OH group, an NCO group, an NH2 group, an NHR group (where R is alkyl group) and a COY group (where Y is a hydrophilic group); RF is the fluoroalkyl group having a carbon number of 2 to 10 and a molecular weight of 119 to 1000; 3D-SN is the three-dimensional silica network section; B is selected from the group consisting of an O, O?C—O, NH—C?O and NR—C?O (where R is alkyl group); E is O, O?C—O, NH—C?O or NR—C?O (where R is alkyl group); L is (CH2O)l—[Si(CH3)2O]k—(CH2O)l-?, (CF2)j-? or (CF2O)h-? where ? is COY group (where Y is hydrophilic group), NCO group, NH2 group, NHR group (R is alkyl group), R grou