Abstract: There are disclosed polybenzoxazole precursors which can be processed by centrifugal techniques, which can be cyclized to polybenzoxazoles on substrates without difficulty, and which after cyclization to polybenzoxazoles exhibit a high temperature stability. In particular, these precursors and the polybenzoxazoles prepared from them possess high resistance against the diffusion of metals.

Abstract: A block copolymer for use as a solid polymer electrolyte, said block copolymer having at least first and second segments, the first segments being hydrophilic segments provided with acidic substituents for proton transport and the second segments being hydrophobic segments having substantially no acidic substituents and serving for the mechanical integrity of the solid polymer electrolyte. Also described and claimed are an ion-conductive membrane made from block copolymers of the aforementioned kind as well as methods of preparing such block copolymers and membranes based thereon. The membranes have improved proton conductivity and improved mechanical properties in the presence of water making them particularly suitable for use in fuel cells.

Abstract: Bis-o-aminophenols and o-aminophenolcarboxylic acids have the following structures: A1 to A7 are, independently of each other, H, F, CH3, CF3, OCH3 or OCF3. T is an aromatic or heterocyclic residue. A method for preparing bis-o-aminophenols and o-aminophenolcarboxylic acids is also provided.

Abstract: A binder composition, at least containing an inorganic filler and a thermoplastic block copolyurethane having in each case at least one soft segment (A) and at least one hard segment (B), at least one hard segment (B) containing a structural element of the formula I is used in particular for the production of magnetic recording media.

Abstract: There are disclosed polybenzoxazole precursors which can be processed by centrifugal techniques, which can be cyclized to polybenzoxazoles on substrates without difficulty, and which after cyclization to polybenzoxazoles exhibit a high temperature stability. In particular, these precursors and the polybenzoxazoles prepared from them possess high resistance against the diffusion of metals.

Abstract: Bis-o-aminophenols and o-aminophenolcarboxylic acids have the following structures: 1

Abstract: The present invention provides processes for preparing polyesters. The processes include (a) providing a polymerization medium comprising carbon dioxide, (b) contacting a monomer capable of forming a polyester polymer with the polymerization medium, and (c) polymerizing the monomer in the polymerization medium. The processes of the present invention include preparing polyesters by direct esterification polymerization, transesterification polymerization, melt acidolysis polymerization and acid halide polymerization. As a further aspect, the present invention provides a method of separating the polyester produced from the polymerization medium. Polyester polymers prepared according to the methods of the present invention are also provided.

Abstract: The present invention provides processes for preparing polyesters. The processes include (a) providing a polymerization medium comprising carbon dioxide, (b) contacting a monomer capable of forming a polyester polymer with the polymerization medium, and (c) polymerizing the monomer in the polymerization medium. The processes of the present invention include preparing polyesters by direct esterification polymerization, transesterification polymerization, melt acidolysis polymerization and acid halide polymerization. As a further aspect, the present invention provides a method of separating the polyester produced from the polymerization medium. Polyester polymers prepared according to the methods of the present invention are also provided.

Abstract: The present invention provides processes for preparing polyesters. The processes include (a) providing a polymerization medium comprising carbon dioxide, (b) contacting a monomer capable of forming a polyester polymer with the polymerization medium, and (c) polymerizing the monomer in the polymerization medium. The processes of the present invention include preparing polyesters by direct esterification polymerization, transesterification polymerization, melt acidolysis polymerization and acid halide polymerization. As a further aspect, the present invention provides a method of separating the polyester produced from the polymerization medium. Polyester polymers prepared according to the methods of the present invention are also provided.

Abstract: A lens having a variable index of refraction and a point of symmetry is fabricated from a plurality of substantially identically shaped parts. Each of the parts is pyramidal in configuration and has a base and a plurality of sides extending from the base to an apex. Each of the parts has a coefficient of refraction which varies from the base to the apex.

Abstract: A printed circuit board includes an oscillator and a modulator. The oscillator includes a first printed inductor and a capacitive diode which are printed on one side of the printed circuit board. The modulator includes a second printed inductor coupled to the first printed inductor and printed on the same side of the printed circuit board as the oscillator. A conductive surface at a reference potential is arranged the other side of the printed circuit board and in the vicinity of the oscillator and the modulator and electrically coupled to the oscillator and the modulator using conductive through holes.

Abstract: The invention presents a method for the fabrication or production of three-dimensional lenses with a variable refractive index by wrapping a material with a given refractive index. It is preferred, that this material has the shape of a thread, which might be cylindrical. The preferred shape of the lens to be produced is spherical or semi-spherical, which can be achieved by an appropiate wrapping process or by cutting the spherical shape. By the inventive method it is possible to produce the said lenses with a smooth varying of the refractive index. It is preferred to use the produced lenses as part of a microwave antenna system.

Abstract: Polyether ketones and polyether sulfones based on phenylindane and the use thereof for optical systemsPolymeric ethers containing phenylindane units, of the formula ##STR1## in which X=CO or SO.sub.2,Y=a divalent heteroarylene radical or an arylene radical or a divalent group of two aryl radicals which are bonded to one another via a bridge,R.sup.1 =CH.sub.3 ; R.sup.2 =R.sup.3 =H, orR.sup.2 =CH.sub.3 ; R.sup.1 =R.sup.3 =(C.sub.1 to C.sub.16)-alkyl or aryl, orR.sup.1 =CH.sub.3 ; R.sub.3 =H; R.sup.2 =(C.sub.1 to C.sub.16)-alkyl or aryl,are transparent and are suitable for optical systems.

Abstract: A circuit arrangement for switching-through (transit switching) of RF-signals is provided. The signals from several RF-signal sources are switched via controlled diode paths wherein capacitance diodes are used for achieving a high value of decoupling between sources in the unenergized state.

Abstract: Polyethers which contain recurring units of the formula I ##STR1## in which A is a divalent aryl or heteroaryl radical,X is O, S or NR,Z is a divalent aryl or heteroaryl radical or an alkynyl, azo or (CF.sub.2) group, andR is arylare synthesized. The polyethers can be used as thermoplastics for the production of injection-molded articles, extrudates, polymer blends and coatings and for the production of films and membranes from solution.

Abstract: A circuit for generating a cut-off voltage for the switching diodes in a high frequency filter by rectifying the output signal of an oscillator includes a first diode which has a low threshold voltage and which rectifies the output signal to apply the cut-off voltage to the switching diodes in a first mode of operation. A second diode, having a low resistance, is parallel to the first diode and by-passes the first diode in a second mode of operation.

Abstract: A circuit arrangement for distributing an antenna signal to input terminals of two appliances. One of these appliances is connected to a variable frequency modulator. An attenuating filter stage is connected between a pre-amplifier and the input of the appliance that is connected to the modulator. The pre-amplifier receives and amplifies the antenna signal. The attenuating filter stage is a frequency trap which has a trapping frequency that is identical to the modulator frequency and is synchronized with tuning of the modulator frequency. The attenuating filter stage, furthermore, is always exactly tuned to the frequency of the modulator and has a tuned frequency that is always aligned in parallel to the frequency of an oscillator in the modulator, so that modulation is not present.

Abstract: The individual radio frequency filters are balanced successively by application of an auxiliary frequency at the antenna input. The auxiliary frequency is disposed between the frequency of the picture carrier and the sound carrier of the selected channel. The resulting intermediate frequency is disposed in the intermediate frequency region between the picture and sound intermediate frequency. The measurement voltage is picked up at the automatic gain control output of the radio frequency amplifier. The reference circuit is switched with regard to its frequency to the intermediate frequency during the balancing. The capacitance at the automatic gain control output is decreased during that time.

Abstract: The present invention provides a radio frequency device circuit arrangement with a UHF and VHF receiver part of a television set, which television set has a single base circuit board frame construction. The board has a soldering side and a component side. A rectangular box frame with a separating wall is attached to the board on the component side. Two subcircuit module boards are attached to circuit board frame and cooperate with the box frame to form the RF circuit arrangement.

Abstract: A fuel pressure regulator comprising a housing, a movable diaphragm mounted within the housing, the diaphragm including a first side communicating with the atmosphere and an opposite second side having first and second portions, a fuel chamber partially defined by the first portion of the second side of the diaphragm, a constant pressure chamber partially defined by the second portion of the second side of the diaphragm, a fuel inlet communicating with the fuel chamber, and a fuel outlet having an inlet end located adjacent the diaphragm within the fuel chamber and being selectively communicable with the fuel chamber in response to movement of the diaphragm relative to the inlet end.