The formation of superabundant vacancies (SAVs; vacancy-hydrogen clusters) was studied in Nb-H alloys by means of resistivity measurements as a function of temperature, pressure and H concentration. The formation energy of a vac-H cluster (0.3 ± 0.1 eV), which is 1/10 of the formation energy of a vacancy in Nb, is explained tentatively as being the consequence of six H atoms trapped by a vacancy with the average binding energy of 0.46 eV/H atom. The SAVs were introduced from the external surface, and transported into the interior by direct bulk diffusion and/or by fast diffusion along dislocations. The activation volumes for the formation and migration of vac-H clusters were determined to be 3.7 and 5.3 Å 3 , respectively.

No abstract

High frequency ultrasound imaging has realized high resolution in vivo imaging of the biological tissues at a microscopic level. Human skin structure, especially sebaceous glands at the deep part of the dermis, was observed by three-dimensional ultrasound microscopy with the central frequency of 120 MHz. The visco-elasticity and surface sebum level of the observed region were measured by established testing devices. Both sebaceous glands density and surface sebum level were higher in cheek than those in forearm. The viscosity of forearm was lower than that of cheek. These results suggest that sebaceous glands may act as cushions of the skin besides their classical role of secreting sebum and some hormones. High frequency ultrasound imaging contributes to the evaluation of human skin aging.

From the results of the study, it was revealed that both the setting expansion and compressive strength of gypsum products using the slightly acidic hypochlorous acid water showed almost the same characteristics as those using tap water.

Patient : The patient was a 27-year-old male with a chief complaint of pain in the upper-left incisors. These teeth were diagnosed as chronic apical periodontitis and the cemented post-cores of these teeth had to be removed for the following infected root canal treatment. The volume of metal core of the upper left central incisor had already been greatly reduced to an unfavorable size, and we failed to remove the cemented post-core using the Little Giant Post Puller. A supplementary device that fitted to the core was cast to aid the Little Giant Post Puller to work properly. By using this device, the jaws of the Post Puller gripped the core securely so that the instrument did not slip as the post was being unseated. Finally, the post-core was successfully removed without any troubles such as root fracture or postoperative pain. Discussion : In the case reported here, the volume of metal core had already been greatly reduced by the previous doctor, and there was a risk of metal fracture of the core if additional trimming of the core had been performed to accommodate the size of the Post Puller. The success in removing the post-core by the aid of the supplementary device might have been due to the skill of the operator, who was experienced in using the Post Puller and also well versed in both the advantages and disadvantages of the instrument. Conclusions : Great satisfaction of both the patient and the operator were obtained, since the fabricated supplementary device worked well under the operator's proper judgment for solving this difficult case.