Abstract: A syringe for extruding heated thermoplastic materials through a hollow needle is disclosed. This syringe is particularly useful in obturating root canal cavities, or other dental cavities, with gutta-percha or similar materials.

Abstract: Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60.degree. in elevation angle by 120.degree. or more in the azimuth sectors with a collector concentration ratio of approximately 3.0. Miniaturized construction of the circular dielectric rods with internal absorbers reduces the weight per area of glass, plastic and metal used in the collector panels. No external parts or insulation are needed as heat losses are low due to partial vacuum or low conductivity gas surrounding heated portions of the collector.

Abstract: An electrically heated endodontic syringe for injecting thermoplastic material, such as gutta percha, into a root canal cavity includes a syringe barrel for holding a supply of thermoplastic material, a heater body threadedly attached at one end to the syringe barrel and an injection needle threadedly secured to the other end of the heater body by means of a hub. A manual plunger is provided in the syringe barrel for ejecting thermoplastic material from the barrel through the heater body, hub and needle into the root canal cavity. The barrel and plunger are made of materials having a low coefficient thermal conductivity of less than about 20 Btu/(hr)(ft.sup.2) (F..degree./ft) and a thermally insulating washer is positioned between the barrel and the heater body to minimize heat transfer to the barrel. The heater body, hub and needle are made of materials having a high coefficient of thermal conductivity of at least about 200 Btu/(hr) (ft.sup.2) (.degree.F./ft) to maximize heat flow to the needle.