Abstract: A devices for measuring the mass of a flowing medium, having a temperature-sensitive measuring element, in which accurate medium flow measurement can be made in the presence of a pulsating flow which is characterized by flow fluctuations. In order to provide accurate measurements, the device has a structure which is installed in the measuring conduit in a region of its inside wall upstream and downstream of the measuring element. The structure has friction faces exposed to the oncoming flow in which the friction faces effect a flow resistance which can be varied by the intensity of the flow fluctuations, only in the presence of a pulsating flow, so that the flow is positively displaced more or less into the region of the measuring element, in order to increase the flow velocity and to compensate for the measurement errors. The invention is for measuring the mass of a flowing medium in the intake of an internal combustion engine.

Abstract: Bisphenols are prepared bya) reacting a phenolic compound with a carbonyl compound in a reaction mixture, containing the carbonyl compound, a stoichiometric excess of the phenolic compound and a catalyst, to produce a product mixture containing a bisphenol,b) separating bisphenol from the product mixture to leave a mother liquor andc) recycling at least a portion of the mother liquor to the reaction mixture.At least a portion of the phenolic compound is contacted with a strongly acidic cation exchange resin and a strongly basic anion exchange resin before the phenolic compound is used in the reaction step a) and/or at least a portion of the product mixture and/or at least a portion or the mother liquor is contacted with a strongly acidic cation exchange resin and a strongly basic anion exchange resin before mother liquor is recycled to the reaction mixture.