Abstract: An electric circuit for the conversion of a multiplicity of commercial power voltages to a predetermined supply voltage which is independent of the respective commercial power voltage, for a device with high electrical power requirements of high output, in the range up to 40 kW, such as a bobbin winding machine. The circuit contains a rectifier stage for generating a primary intermediate circuit DC voltage, a converter stage with power switches for generating a rectangular AC voltage, a high-power transformer with a connected secondary control circuit and a control stage which triggers the power switches at zero voltage in a phase-shift mode with a variable frequency and pulse width of the rectangular AC voltage as a function of the input voltage of the rectifier stage, the transformer primary winding current and both the voltage and the current in the secondary intermediate circuit.

Abstract: Chromogenic and fluorogenic substrates for .beta.-lactamase, methods for synthesis thereof and methods for detecting .beta.-lactamase in a sample are provided. The substrates are substantially colorless or substantially nonfluorescent .beta.-lactam compounds which include an electronegative leaving group. The leaving group comprises a carbamate, carbonate, thiocarbamate or thiocarbonate linkage and a fluorescent moiety or a moiety capable of producing a visually detectable colored product. Upon cleavage of the lactam ring by .beta.-lactamase, the leaving group is liberated and fluorescence or a colored product is produced.

Abstract: Chromogenic and fluorogenic substrates for .beta.-lactamase, methods for synthesis thereof and methods for detecting .beta.-lactamase in a sample are provided. The substrates are substantially colorless or substantially nonfluorescent .beta.-lactam compounds which include an electronegative leaving group. The leaving group comprises a carbamate, carbonate, thiocarbamate or thiocarbonate linkage and a fluorescent moiety or a moiety capable of producing a visually detectable colored product. Upon cleavage of the lactam ring by .beta.-lactamase, the leaving group is liberated and fluorescence or a colored product is produced.

Abstract: Chromogenic and fluorogenic substrates for .beta.-lactamase, methods for synthesis thereof and methods for detecting .beta.-lactamase in a sample are provided. The substrates are substantially colorless or substantially nonfluorescent .beta.-lactam compounds which include an electronegative leaving group. The leaving group comprises a carbamate, carbonate, thiocarbamate or thiocarbonate linkage and a fluorescent moiety or a moiety capable of producing a visually detectable colored product. Upon cleavage of the lactam ring by .beta.-lactamase, the leaving group is liberated and fluorescence or a colored product is produced.

Abstract: Chromogenic and fluorogenic substrates for .beta.-lactamase, methods for synthesis thereof and methods for detecting .beta.-lactamase in a sample are provided. The substrates are substantially colorless or substantially nonfluorescent .beta.-lactam compounds which include an electronegative leaving group. The leaving group comprises a carbamate, carbonate, thiocarbamate or thiocarbonate linkage and a fluorescent moiety or a moiety capable of producing a visually detectable colored product. Upon cleavage of the lactam ring by .beta.-lactamase, the leaving group is liberated and fluorescence or a colored product is produced.

Abstract: A method for enzyme immunoassay includes contacting under binding conditions a liquid suspected of containing an analyte, an antianalyte and a tracer having conjugated thereto delta 5-3-ketosteroid isomerase. A bound fraction is separated from the liquid and incubated in a second liquid with a delta 5-3-ketosteroid substrate. Isomerase on the bound fraction converts the substrate to the corresponding delta 4-3-ketosteroid. A tetrazolium salt and a base are added. Unconverted delta 5-3-ketosteroid reduces the tetrazolium salt to a formazan which imparts a color to the liquid. A signal associated with the color may be used to detect or to measure the concentration of the analyte in the liquid. The invention includes a kit of materials useful in performing the assay of the invention.