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Histopathologic, histochemical, and morphometric studies were done on 80 medial stumps of torn rotator cuff tendons to clarify the cause of tears. A high prevalence and diffuse distribution of degenerative changes were observed in the rotator cuff tendons including thinning and disorientation of collagen fibers, myxoid degeneration, hyaline degeneration, chondroid metaplasia, calcification, vascularproliferation, and fatty infiltration. No distinct inflammatory reaction was observed. Thinning and disorientation of collagen fibers, myxoid degeneration, and hyaline degeneration were seen in all cases. All changes except vascular proliferation and fatty infiltration were more pronounced in the middle to deep layers of the tendons than in the superficial layer. The collagen fibers were disoriented in the deep layer of the tendons, shown by microscopic image analysis. The frequency and distribution of thinning and disorientation of collagen fibers, myxoid degeneration, and hyaline degeneration suggest that these are early degenerative processes. Chondroid metaplasia and calcification may be chronic pathologic changes that occur after tearing regardless of the type of tear. Preexisting degenerative change in the middle and deep layers of the tendon in association with microtrauma seems to be the main cause of rotator cuff tears.

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We calculate the potential energy curves for H adsorption on and absorption in Cu(111), Pt(111), and Pd(111) within the density functional theory. We show stronger dependence of the potential energies on the lateral position of the H atom at the position further from the surface in the case of Pt(111) than one in the case of Pd(111), and no lateral position dependence in the case of Cu(111). Contrary to this, when the H atom comes close to and adsorbs on the surface, the dependence of its adsorption energy (a depth of potential well outside the surface) on the lateral position in the case of Cu(111) is stronger than one in the case of Pd(111), and such dependencies are hardly seen, and the adsorption energies are nearly the same in the case of Pt(111). When the H atom penetrates the first layer of the surface, the activation barrier at a so-called face-centered-cubic hollow site in the case of Pd(111) is the lowest in three surfaces.

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