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The transition between Néel and Bloch walls is shown to be gradual rather than abrupt, resulting in a wall with Néel and Bloch components superposed. For films thick enough so that such a transition can occur, the wall is a pure Néel wall if φf, the acute angle between the wall normal in the plane of the film and the magnetization at the edge of the wall (half the angle between the magnetization vectors in the two domains separated by the wall) is less than a critical value. For φf larger than that critical value but less than π/2, the wall contains both Néel and Bloch components. When φf is π/2, i.e., a 180° wall, the wall is of the pure Bloch type; however, this situation is often unstable, resulting in a transition wall with the Néel component reversing periodically in distance along the wall in a crosstie-like structure. These conclusions are supported by Lorentz micrographs.

The aim of the present study was to assess in vitro the heat generated within the implant body when preparing titanium implants of the ITI Dental Implant System to estimate the potential risk of tissue damage of individual abutment preparation. The speed and the pressure were applied according to routine clinical procedures used in the patient's mouth. Much attention was paid to ensure optimal cooling at the point where the implant and secondary part were being cut. For each of 3 preparations the change from the original temperature was measured over a period of 40 s. Each type of preparation was repeated on 5 implants fitted with temperature probes. Three different preparatory procedures performed with rotating diamond burs and stainless steel finishing burs under cooling with spray from the dental unit may result in a maximal increase in temperature of 10 degrees, 7 degrees and 3 degrees measured coronally, both at the implant shoulder and at the coronal extent of the plasma-sprayed surface after 10 s. The use of additional spray and pressured air significantly reduced this maximal increase to 5 degrees C, 5 degrees C and 4 degrees C, respectively at 10 s. At the 30-s and 40-s time points, all the measured temperatures were significantly lower. Preparation of implants or abutments does not lead to detrimental effects on peri-implant tissues provided that adequate cooling with spray is used. However, without cooling, extreme overheating could be provoked, reaching the critical temperature that would lead to irreversible bone damage within only a few seconds.

The damping properties of Fe-Cr and Fe-Cr based alloys have been investigated by the cantilever method and the resonant bar method. The change in damping capacity is studied as a function of several parameters including temperature, magnetic field, cold work and heat treatment. The results are correlated with measurements of the coercive force. Binary Fe-Cr alloys with 12-14 % Cr exhibited damping capacities as high as 80 % when heat treated at 1200 °C while the alloy Fe-12Cr-3Al already exhibited damping capacities of the order of 40-60 % when heat treated at temperatures above 750 °C