Abstract: In order to electrically apply fluoride by means of iontophoresis on a tooth an intermittent direct current is made to flow through the tooth. More particularly, the intermittent direct current has a waveform whose leading edge immediately rises to a peak and which decreases exponentially in time. As a result electrochemical polarization may be avoided and the ratio of the current conduction time to the repetition period may be increased so that the uptake efficiency of fluoride by the tooth may be considerably improved in a smooth manner without the need of impressing an excessive current on the tooth. Therefore adverse effects on nerve systems may be avoided, a patient under treatment feels no pain and no unpleasant stimulus, and the tooth's substance may be so improved as to be free from dental caries or decay.

Abstract: There is provided a charging system for secondary batteries comprising a high-frequency power supply circuit consisting of a transistor DC-DC converter and a control circuit for preventing the overcharging of a battery to be charged, whereby the oscillation of the high-frequency power supply circuit is controlled by the control circuit. Thus, the size and weight of the charging system of this invention are reduced.

Abstract: A pad comprising at least one sheet of material having a thermoplastic resinous composition and a heater actuable to heat and soften the sheet, the pad being for use in alignment of machine equipment, rails, beams, girders, or other constructional elements relative to a horizontal base, vertical or inclined line, or to other constructional elements. In use the pad is placed between the equipment, rail or the like and a support or abutment therefor, and the heater is actuated so as to soften the pad just sufficiently that the weight of object or a force thereon reduces the thickness of the pad an amount equal to the desired movement of the object necessary to achieve the desired alignment.

Abstract: An electrothermally deformable levelling pad utilizable in padding, levelling or aligning girders, rails or any other constructional or structural elements. The levelling pad comprises at least one thermoplastic plate member and an electric heater for heating the thermoplastic plate member to soften or melt to cause the overall thickness of the pad to reduce to a value sufficient to bring an article or machine to a predetermined level. The plate member is made of a thermoplastic random-copolymerized polyester which comprises an acid component and a glycol component.