Abstract: To provide a novel diamine, and a polyimide precursor and a polyimide using it. A diamine represented by the formula (1): wherein each of X1 and X5 which are independent of each other, is a single bond or the like; each of X2 and X4 which are independent of each other, is —CH2— or the like; X3 is a C1-6 alkylene or the like; each of Y1 and Y2 which are independent of each other, is a single bond or the like; R is a C1-20 linear, branched or cyclic hydrocarbon group; and a is 0 or 1).

Abstract: To provide a novel diamine, and a polyimide precursor and a polyimide using it. A diamine represented by the formula (1): wherein each of X1 and X5 which are independent of each other, is a single bond or the like; each of X2 and X4 which are independent of each other, is —CH2— or the like; X3 is a C1-6 alkylene or the like; each of Y1 and Y2 which are independent of each other, is a single bond or the like; R is a C1-20 linear, branched or cyclic hydrocarbon group; and a is 0 or 1).

Abstract: To provide a novel diamine which is useful as the starting material of a novel polyimide precursor or polyimide which can provide a liquid crystal alignment film having a low volume resistivity, a liquid crystal aligning agent containing these polymers, and a liquid crystal alignment film.

Abstract: To provide a polyamic acid ester-containing polyimide precursor composition having a good storage stability, from which a polyimide film having a high imidization degree and excellent adhesion to an inorganic substrate can be obtained. A polyimide precursor composition comprising a polyamic acid ester, a thermal imidization accelerator and a solvent, wherein the thermal imidization accelerator is a compound which has a carboxy group and an amino group or an imino group which is deprotected by heat to show basicity, and which will not accelerate the imidization of the polyamic acid ester before the protecting group leaves, and a polyimide precursor composition containing a silane coupling agent.

Abstract: To provide a polyamic acid ester-containing polyimide precursor composition having a good storage stability, from which a polyimide film having a high imidization degree and excellent adhesion to an inorganic substrate can be obtained. A polyimide precursor composition comprising a polyamic acid ester, a thermal imidization accelerator and a solvent, wherein the thermal imidization accelerator is a compound which has a carboxy group and an amino group or an imino group which is deprotected by heat to show basicity, and which will not accelerate the imidization of the polyamic acid ester before the protecting group leaves, and a polyimide precursor composition containing a silane coupling agent.

Abstract: To provide a novel polyimide precursor or polyimide which can provide a liquid crystal alignment film having a low volume resistivity, a liquid crystal aligning agent containing these polymers, a liquid crystal alignment film and a novel diamine which is useful as the starting material of these polymers.

Abstract: In a nuclear fusion device having a torus type vacuum shell around which toroidal coils and poloidal coils are wound and arranged and whose interior is maintained in a high vacuum state, the bending rigidity of a shell wall in a circular cross section of the vacuum shell is made higher on the outer periphery side than on the inner periphery side of the circular cross section, thereby to prevent any deformation of the vacuum shell due to a magnetic force and any damage of the shell attendant upon the deformation in a process in which the coils are energized to confine a plasma within the vacuum shell. Moreover, without increasing the inner diameter of the circular cross section of the vacuum shell, the coils are located in proximity to the plasma so as to enhance the plasma producing efficiency.

Abstract: An apparatus for measuring mechanical stress in one direction (along the x-axis) in the surface of a sample, using white X-rays, wherein white X-rays are cast onto the surface of the sample from on one side of the plane (z-x plane) containing the white X-rays cast position on the surface of the sample, being perpendicular to the surface (x-y plane) of the sample and extending in the direction (along x-axis) along which the stress is measured; the energy of the X-rays diffracted by the lattice planes parallel to the surface of the sample, is detected at a predetermined Bragg angle while the energy of the X-rays diffracted by the lattice planes whose normals are contained in the z-x plane and which incline at an angle with respect to the surface of the sample, is detected also at the same Bragg angle; and the stress .sigma..sub.x in the x-axis direction in the sample surface is calculated on the basis of the difference between the two energies according to the expression ##EQU1## WHERE E.sub.