Abstract: A method of detecting undesired microorganisms when cells are cultured in a light permeable container is disclosed. TV camera monitors the image of a well containing microorganisms through a microscope. The output of the TV camera is processed by a picture digital processor so as to count the number of cultured living cells. On the other hand, change of the light absorption of the visible light by the cultured solution is measured. Then the number of undesired microorganisms can be calculated by the number of the living cells and change of the light absorption.

Abstract: A particle analyzer which comprises a constricted passage for the passage of fine particles contained in a suspension therethrough for isolation, upstream and downstream passages communicated with the constricted passage and positioned on upstream and downstream sides of the constricted passage with respect to the direction of flow of the suspension, a detector including upstream and downstream electrodes disposed in the upstream and downstream passages, respectively, so as to confront with each other for detecting the fine particles being passed through the constricted passage, and a cleansing passage communicated with either one of the upstream and downstream passages for the supply of a cleansing liquid.

Abstract: A method and apparatus for the continued incubation of cells in a liquid culture medium. When the pH value of the culture medium deviates during the incubation from a pH range suited for the growth or multiplication of the cells, the culture medium is automatically replaced. Whether or not the pH value of the culture medium has deviated from the acceptable pH range is determined by measuring the intensity of light absorbed by the culture medium.

Abstract: A plastic optical fiber comprising a core of a copolymer of an aryl methacrylate and an alkyl methacrylate and a cladding of a copolymer of vinylidene fluoride and a fluoroolefin provided on the core, the copolymer of the cladding having a melting point of at least 120.degree. C. and a fluoroolefin content of at least 3 mol %.

Abstract: A process for producing a plastic optical fiber which consists of a core made of a homo- or co-polymer of alkyl methacrylate and a cladding made of a fluorine-containing polymer, which process comprising forming the cladding around the core and irradiating the optical fiber with an electron beam, the optical fiber produced by the process being used at a temperature higher than 80.degree. C. without significant loss of light transmission.

Abstract: A plastic optical fiber comprising a core of a copolymer of an alkyl methacrylate and a styrene derivative and a cladding of a copolymer of vinylidene fluoride and a perfluoroolefin provided on the core, the copolymer of the cladding having a melting point of at least 120.degree. C. and a perfluoroolefin content in the range of from 3 mol % to 70 mol %.

Abstract: A Schmidt circuit comprises a first series circuit including an impedance device and a series connection of a first and second MOS field effect transistors, and a second series circuit including a series connection of a third and fourth MOS field effect transistors. The first series circuit is connected between a voltage supply and the ground and the second series circuit is connected between the voltage supply and the junction of the first and second MOS field effect transistors. The gates, as commonly connected, of the first and second MOS field effect transistors are supplied with an input voltage, and the junction of the impedance device and the first MOS field effect transistor is connected to the gate of the third MOS field effect transistor, so that an output voltage is withdrawn therefrom.