A rare case of splenic epidermoid cyst (SEC) of the pancreas discovered in a 32‐year‐old Japanese female is reported. The lesion, 5x6cm in size including caseous material and serous fluid in the lumen, was discovered by ultrasonography and computed tomography at the tail of the pancreas and was easily removed. Histopathologically, the cystic wall consisted of three components: the inside was lined by mature squamous epithelium with keratinization, the middle layer consisted of splenic pulp with a sinus structure, and the peripheral layer was dense fibrous connective tissue in which some involutional pancreatic ducts and islets were recognized. The literature about SEC of the pancreas is discussed in comparison with other types of epidermoid cyst including lymphoepithelial cyst and dermoid cyst in the pancreas. Acta Pathol Jpn 41: 916 921, 1991.

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In this study, the electrical impedance method was developed to monitor the thickness and breakdown ratio of oil films in elliptical elastohydrodynamic (EHD) contacts of practical ball bearings. First, it is theoretically shown that the oil film thickness and breakdown ratio can be simultaneously measured from the complex impedance generated when a sinusoidal voltage is applied to elliptical contacts. Subsequently, lubrication conditions of practical ball bearings were monitored at an ambient temperature to verify the measurement accuracy of the developed method. The oil film thickness in the low-speed range was consistent with the theoretical value calculated by Hamrock-Dowson equation. However, in the high-speed range, the oil film was thinner than the theoretical value considered an ambient temperature. In this high-speed range, the results of both the outer ring temperature and bearing torque revealed that the viscous shear heating and starvation were occurring simultaneously, thus supporting that the measured thickness would be thinner than the theoretical value. Besides, the developed method can also measure the breakdown ratio, confirming that it increases in the lowspeed range where the bearing torque increases. That is, it indicates that not only the oil film thickness but also the breakdown ratio can be evaluated quantitatively.

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Boundary lubrication is one of the most interesting topics in the field of tribology, and a lot of studies have been conducted from the past for understanding the behaviour of boundary lubrication films. General boundary lubrication films are formed by the adsorption of additives mixed into lubricant, and then the tribological performances are drastically improved in many cases. However, there is still room for discussion on the “actual” behaviour of adsorbed additive layer in the tribological condition, that is, under high pressure and/or with external forces. This paper showed the “growing” behaviour of an adsorbed additive layer onto metal surface due to high pressure by means of neutron reflectometry in conjunction with the result obtained through cross‐sectional imaging by frequency‐modulation atomic force microscopy. In addition, the nanotribological study using atomic force microscopy with a colloidal probe showed that the coefficient of friction in the pre‐scratched area was lower than that in the non‐scratched area and that the reduction ratio for lubricant with additive was higher than that for lubricant without additive. This result indicates that growth of the adsorbed additive layer contributed more greatly to a reduction in the coefficient of friction.