Abstract: A device suitable for insertion into a mammalian body comprises an elongated tube or cannula, an elastic member for bending the cannula, and a straightener preventing the elastic member from bending the cannula. The straightener and elastic member are capable of relative axial movement, so that the straightener can be positioned to prevent or allow the elastic from bending the cannula. Preferably the elastic member is formed from a superelastic shape-memory alloy. Other versions of the device without a straightener are described.

Abstract: A suture and a suturing method are set forth for suturing a wound in the tissue of a patient and defined by tissue edges. The suture comprises an alloy member having a first end portion, a second end portion, and a first undeformed shape. It is deformable into a second deformed shape. The member has the property of recovering from its second shape towards its first shape upon the second shape being subjected to specified conditions. The first shape is a suturing loop adapted to draw and hold the tissue edges defining the wound together. The second shape is adapted to allow the member to be drawn through the tissue in position for the loop to form. The method comprises inserting such a member while it is in its second shape into position for it to assume its first suturing loop shape and subjecting it to conditions which cause it to recover towards its first shape.

Abstract: An electrical heater which has a conductive polymer resistive element and two laminar electrodes. The electrodes are shaped and positioned such that there is a continuous margin around the periphery of the resistive element on at least one surface. The margin is particularly useful in reducing arcing which may occur between the electrodes.

Abstract: Circuit protection devices which comprise conductive polymer PTC elements and which will provide repeated protection against sudden increases in current to high levels, e.g. 5 amps or more, in circuits which operate at, or are subject to fault conditions arising from, voltages greater than 100 volts, e.g. mains supply voltages. A particularly valuable use of the devices is in the protection of circuitry in telecommunication apparatus which normally operates at battery voltages, e.g. up to 75 volts, but which can be accidentally subject to voltages above 120 volts.

Abstract: A PTC device is used to protect a power circuit from excessive heat and/or excessive current in an electrical system which comprises a separate control circuit as well as the power circuit. The PTC device is in one of said circuits and is thermally coupled to a resistive element in the other of said circuits. A preferred means for thermally coupling these two components is a metal strap which at least partially encircles the resistive element and extends over at least a portion of the surface of the PTC device.

Abstract: Circuit protection devices which comprise conductive polymer PTC elements and which will provide repeated protection against sudden increases in current to high levels, e.g. 5 amps or more, in circuits which operate at, or are subject to fault conditions arising from, voltages greater than 100 volts, e.g. mains supply voltages. A particularly valuable use of the devices is in the protection of circuitry in telecommunication apparatus which normally operates at battery voltages, e.g. up to 75 volts, but which can be accidentally subject to voltages above 120 volts.

Abstract: A heater for heating liquids such as water in an aquarium comprises a water-impermeable housing including a heating section for immersion in the water. Within the heating section of the housing is a flexible, distributed planar heating element. The housing is resistant to breakage from mechanical and operating abuse and has a high heat transfer coefficient and high heat distortion temperature. To prevent the housing from melting when a control element of the heater malfunctions, preferably the aquarium heater includes temperature limiting means such as a circuit protection element comprising a material having a positive temperature coefficient of resistance. Preferably, the heating section of the housing is fabricated with large surface area walls to accommodate the planar heating element, and is provided with coupling means for maintaining the heating element thermally coupled to the walls of the heating section.

Abstract: Circuit protection devices which comprise two columnar electrodes and a conductive polymer element, at least a part of which is a PTC element. The device is so constructed that if a hot zone forms in the PTC element when current is passed through the device, it forms at a location away from the electrodes, thus increasing the useful life of the device. In one preferred embodiment, the conductive polymer element has an intermediate portion of increased resistance, thus causing the hot zone to be located at or near the intermediate portion. The intermediate portion may be of reduced size and/or be composed of conductive polymer of relatively high resistivity.

Abstract: Circuit protection devices comprising PTC elements, and circuits containing such devices. The devices, which are particularly useful in circuits carrying a steady state current of 0.5 amp or more, can protect the circuit against excessive current, e.g. as a result of a short or a voltage surge, or against excessive temperature, or both. The PTC element is composed of a material, preferably a conductive polymer, having a resistivity less than 10 ohm. cm in the normal operating condition of the circuit, and the device comprises electrodes such that current flows through the PTC element over an area of equivalent diameter d with an average path length t such that d/t is at least 2. The circuit has a normal operating condition in which the device has a low resistance and is in stable thermal equilibrium with its surroundings; however, when a fault condition occurs, the device generates heat by I.sup.

Abstract: Electrical devices which comprise two planar electrodes and a conductive polymer element, at least a part of which is a PTC element. The conductive polymer element has an intermediate portion of increased resistance, resulting from the presence of insulating or high resistance portions within the conductive polymer element, so that when a hot zone is formed in the PTC element, it is located at or near the intermediate portion, away from the electrodes.

Abstract: Electrical devices comprising PTC elements have improved electrical stability when they comprise an oxygen barrier which restricts access of air to the element so that the PTC element absorbs oxygen at a rate less than 10.sup.-6 cc/sec/gram. The devices are for example circuit control devices or self-limiting heaters. Preferred PTC elements comprise a polymer having dispersed therein carbon black and an additive which stabilizes the polymer against degradation, especially an organic antioxidant. The oxygen barrier may for example be a layer of a polymeric composition or a self-supporting container principally made of metal and filled with an inert gas.

Abstract: A heater for heating liquids such as water in an aquarium comprises a water-impermeable housing including a heating section for immersion in the water. Within the heating section of the housing is a flexible, distributed planar heating element. The housing is resistant to breakage from mechanical and operating abuse and has a high heat transfer coefficient and high heat distortion temperature. To prevent the housing from melting when a control element of the heater malfunctions, preferably the aquarium heater includes temperature limiting means such as a circuit protection element comprising a material having a positive temperature coefficient of resistance. Preferably, the heating section of the housing is fabricated with large surface area walls to accommodate the planar heating element, and is provided with coupling means for maintaining the heating element thermally coupled to the walls of the heating section.

Abstract: Circuit protection devices comprising PTC elements, and circuits containing such devices. The devices, which are particularly useful in circuits carrying a steady state current of 0.5 amp or more, can protect the circuit against excessive current, e.g. as a result of a short or a voltage surge, or against excessive temperature, or both. The PTC element is composed of a material, preferably a conductive polymer, having a resistivity less than 10 ohm. cm in the normal operating condition of the circuit, and the device comprises electrodes such that current flows through the PTC element over an area of equivalent diameter d with an average path length t such that d/t is at least 2. The circuit has a normal operating condition in which the device has a low resistance and is in stable thermal equilibrium with its surroundings; however, when a fault condition occurs, the device generates heat by I.sup.

Abstract: An electron beam from an electron column instrument impinges on a target foil to produce a primary X-ray beam which, in turn, passes through a collimator to impinge on a specimen. The X-rays fluoresced from the specimen by the primary X-ray beam are detected by a solid state radiation detection device.