Abstract: A water and oil repellent having excellent desoiling properties composed of a compound comprising at least two terminal segments and an intermediate segment connecting the terminal segments and having a molecular weight of from 800 to 20,000, each terminal segment containing at least one polyfluoroalkyl group connected by a --CONH-- linking group, said intermediate segment being a urethane oligomer containing at least two --CONH-- linking groups and a hydrophilic molecular chain, and said terminal segments and intermediate segment being connected by a --CONH-- linking group.

Abstract: A high performance water and oil repellant composed of a compound comprising at least two terminal segments and an intermediate segment connecting the terminal segments and having a molecular weight of from 800 to 20,000, each terminal segment containing at least one polyfluoroalkyl group connected by a --CONH-- linking group, said intermediate segment being a urethane oligomer containing at least two --CONH-- linking groups in one molecule, and said terminal segments and intermediate segment being connected by a --CONH-- linking group.

Abstract: A plastic-clad light-transmitting fiber having a high NA (numerical aperture) and low transmission loss, which consists essentially of a core of quartz glass or optical glass and a clad of organopolysiloxane, wherein the clad of organopolysiloxane is a cured body having 30% by weight or more of fluorine content, which is obtained by the curing reaction of a vinyl group-containing organofluoropolysiloxane and a hydrogen-containing fluorosilicone compound, and wherein the vinyl group-containing organofluorosiloxane is a copolymerized polysiloxane obtained from a hydrocarbon siloxane unit and a polyfluoroalkyl group-containing siloxane unit, with a ratio of copolymerization of hydrocarbon siloxane unit ranging from 20 to 75 mol %.

Abstract: A surface modifier comprising a block copolymer obtained by polymerizing a polyfluoroalkyl group-containing compound in the presence of a chain transfer agent composed of a polysiloxane having a mercapto group at its terminal, said block copolymer containing polymer segments of said polysiloxane and polymer segments of said compound, as essential components.

Abstract: A low reflectance transparent material having antisoiling properties, which comprises a transparent substrate and a multi-layer coating formed on the substrate, said coating comprising at least one thin layer of a condensation product containing a metal oxide, and a thin layer of a condensation product of a fluorine-containing silicon compound having a polyfluorinated carbon chain or a perfluorocarbon chain, formed thereon.

Abstract: This internal gear pump has: a pump housing formed with a rotor receiving cavity which has a cylindrical circumferential inner wall surface; an outer rotor formed with a generally cylindrical outer surface which fits closely and coaxially in the cylindrical circumferential inner wall surface of the rotor receiving cavity and is rotatable around their mutual central axis within the pump housing, and which is further formed with an inner cavity the defining surface of which is formed with a plurality of internally facing teeth; and an inner rotor, somewhat smaller than the inner cavity of the outer rotor, which is formed with a plurality of externally facing teeth which mesh and cooperate with the internally facing teeth of the outer rotor. A pumping chamber is defined between the outer surface of the inner rotor and the inner surface of the outer rotor between the mutually meshing teeth thereof.

Abstract: A stainproofing agent containing as an active ingredient a polyfluoroalkyl group-containing compound represented by the following general formula and having a molecular weight of from 800 to 3000:(R.sub.f -X-A-CONH).sub.a W-NHCO-A'-Z).sub.3-awhere R.sub.f is a polyfluoroalkyl group having from 1 to 20 carbon atoms, X is --R--, --CON(R.sup.1)--Q-- or --SO.sub.2 N(R.sup.1)--Q-- (where R is a divalent alkylene group, R.sup.1 is a hydrogen atom or a lower alkyl group and Q is a divalent organic group), each of A and A' is --O--, --S-- or --N(Z')-- (where Z' is a hydrogen atom or a monovalent organic group), Z is a monovalent organic group, W is a trivalent organic group, a is an integer of 1, 2 or 3. A process for the stainproofing agent is also disclosed.

Abstract: During starting of an engine, enrichment correction according to engine starting enrichment is executed. After starting of the engine, enrichment correction is transferred gradually with the lapse of time from starting enrichment to normal warm-up enrichment. The transfer speed from starting enrichment to normal warm-up enrichment is changed depending upon whether a throttle valve is in an idle position or not.

Abstract: An air-fuel ratio feedback control system for the internal combustion engine produces a fuel supply control signal by delaying a rich or lean signal obtained by comparing the oxygen concentration in the exhaust gas with a reference value. The turning on of an idle switch operatively connected with the engine throttle valve, a predetermined time after the turning off of the idle switch and the engine speed included in a predetermined region are detected in order to delay the rich or lean signal to rich or lean side by an optimum delay time as selected according to the engine operating conditions, thus feedback controlling the amount of fuel supply.

Abstract: An exhaust gas recirculation system for an internal combustion engine has an exhaust gas recirculation passage, a constant pressure chamber disposed in the exhaust gas recirculation passage, a pressure regulating valve operative in response to the exhaust gas pressure in the constant pressure chamber, a first flow-rate control valve adapted to be actuated by the vacuum regulated by the pressure regulating valve so as to open and close the exhaust gas recirculating passage and a second flow-rate control valve disposed at the upstream side of the constant pressure chamber and adapted to change the cross-sectional area of the exhaust gas recirculating passage in response to the vacuum generated by the internal combustion engine. The exhaust gas recirculation system further has an atmospheric-pressure introduction passage attached to the constant pressure chamber or disposed in a pressure transmitting passage through which the constant pressure chamber is communicated with the pressure regulating valve.

Abstract: An exhaust gas recirculation system for an internal combustion engine, having an exhaust gas recirculation passage, a constant pressure chamber disposed at an intermediate portion of the exhaust gas recirculation passage, a pressure regulating valve operative in response to the exhaust gas pressure in the constant pressure chamber, a first flow-rate control valve actuated by vacuum regulated by the pressure regulating valve and adapted to open and close the exhaust gas recirculation passage and a second flow-rate control valve adapted to change the cross-sectional area of the exhaust gas recirculation passage in response to the level of load applied to the internal combustion engine.

Abstract: Polyfluoroalkyl group-containing compounds are prepared according to the following reaction: ##EQU1## wherein R.sub.f represents perfluoroalkyl groups containing C.sub.1.sub.-23 carbon atoms, R, R' and R" represent hydrogen atoms or lower alkyl groups, and X represents bromine atoms or iodine atoms. The polyfluoroalkyl group-containing esters having the formula R.sub.f CH.sub.2 CH.sub.2 OCOR, are converted by hydrolysis to polyfluoroalkyl group-containing alcohols having the formula R.sub.f CH.sub.2 CH.sub.2 OH wherein R.sub.f is defined as above.