Abstract: In a gas purifier, a gas flow is generated by a fan (15) and passed through a filter arrangement (14). A difference (SF) is measured (16, 19) between pollution levels in the gas flow before and after it has passed the filter arrangement (14). A controller (18) reduces the gas flow when the difference (SF) between the pollution levels drops below a threshold value (Th).

Abstract: A device (5) for measuring temperatures without mechanical contact comprises a bolometer with thermistors (20.sub.1, 20.sub.2, 20.sub.3, 20.sub.4) arranged as a Wheatstone bridge. Some of the thermistors (202, 204) are shielded and some of the thermistors (20.sub.1, 20.sub.3) are not shielded so as to allow or not to allow them, respectively, to receive thermal radiation (25) from an object (OBJ). The thermal radiation heats the non-shielded thermistors and produces an unbalance (v) of the bridge. This unbalance is canceled by heating all the thermistors by an additional heating (18, 26). In the balanced state the temperature of the object is equal to that of the thermistors. The additional heating is preferably achieved by causing the electric power supplied to the bridge to be varied. Computing means (14) enable the temperature of the object to be derived from current/voltage ratios relating to the thermistors.

Abstract: Electric toothbrush comprising means for locating dental plaque An electric toothbrush comprises means (1, 22) for emitting excitation radiation towards teeth (10), means (2, 24) for detecting luminescence return radiation emitted by affected tooth areas, optical fibre means (4a, 4b, 4c) for guiding the excitation radiation, and electrical means (14, 15) for imposing a brushing rhythm. The optical fibre means pick up a narrow beam of return radiation and guide it to the detection means (24) which comprise filter means (40, 42) for extracting at least one useful signal component from a noise component, the useful signal component being in synchronism with the brushing rhythm, the detection means (24) converting the useful signal into a location signal (44) revealing the affected areas.

Abstract: An appliance (5) for toasting a product (10) comprises detection means (12) for detecting variations of a toasting condition of the product during toasting and for allowing a user to adjust the toasting result as desired. The appliance comprises a temperature sensor (13) which measures the temperature of the product. Timing means (14) are started when a predetermined temperature (Td) is reached. The timing means (14) are stopped when either another predetermined temperature (Tf) is reached or when a predetermined period has elapsed. The appliance is also capable of controlling a process of defrosting of the product prior to toasting of said product.

Abstract: The invention relates to a method of manufacturing a field effect transistor comprising at the surface of a substrate of semi-insulating gallium arsenide W an active n-type active layer (102), on which is formed a gate electrode (G) of the Schottky type having at its lower part (15) the general form of a trapezoid, whose minor base is in contact with the active layer, then comprising on either side of the active layer a region of the n.sup.+ type (101 and 101') constituting the source and drain regions, of which the edges adjacent to the active layer are self-aligned with the edges of the major base of the trapezoid, and moreover comprising source (S) and drain (D) electrodes of the ohmic contact type formed at the surface of the regions of the n.sup.+ type.

Abstract: A high-resolution photosensitive composition which can be plasma-developed, including an acrylic a polymer and a photosensitive compound, of the aromatic azide group, in which the polymer contains, in a side chain, at least one aromatic nucleus where at least one chlorine atom (Cl) has replaced at least one hydrogen atom (H), for example ##STR1##

Abstract: A high-resolution photosensitive composition which can be plasma-developed, including an acrylic polymer and a photosensitive compound, of the aromatic azide group, in which the polymer contains, in a side chain, at least one aromatic nucleus where at least one chlorine atom (Cl) has replaced at least one hydrogen atom (H) for example ##STR1##

Abstract: A method of manufacturing a semiconductor device is provided in which a surface of a substrate containing gallium and arsenic is treated in a first plasma containing hydrogen, and then, is coated with a layer of silicon nitride in a second plasma containing silicon and nitrogen. According to the invention, arsenic is added to the first plasma in the form of arsine. Further, the substrate is heated to a temperature below 450.degree. C. during such treatment. After this treatment, but before the coating, the substrate is superficially converted into a surface layer of gallium and arsenic nitrides in a third plasma containing nitrogen. In this way, an almost ideal passivation of the surface of a gallium and arsenic containing substrate can be obtained.