Abstract: The invention provides a temperature-threshold indicator device 10 comprising a sealed housing 12 having at least one surface 14 which is transparent and containing a suspension of inorganic nanoparticles 18 suspended in a liquid medium wherein the suspension undergoes an irreversible detectible change in optical characteristics upon freezing of the liquid medium due to aggregation of the nanoparticles, and wherein the device is provided a with means for association thereof with a product whereby the temperature-threshold indicator device 10 serves to determine whether the product has been exposed to an environment of predetermined coldness.

Abstract: Hence the invention concerns a method which can be used to provide a fluorescent label on bioorganic molecules carrying amino groups such as amino acids, proteins, pharmaceutical agents, antibodies, amino group-modified nucleotides and also polymers and polymer particles carrying amino groups by means of a chemical (covalent) binding. The method is based on the reaction of a pyrylium salt located on a fluorophore F with the amino group of a biomolecule or particle according to the described reaction equation. The method is selective, simple to carry out and results in high labelling yields. The spectral properties of the conjugates differ considerably from those of the starting compounds and their fluorescence quantum yields are often considerably increased.

Abstract: The present invention concerns biological methods of determination using enzymes from the group of oxidases and using optical indicators from the group of lanthanoid-ligand complexes.

Abstract: A method and a sensor for determining acidic gases in gas mixtures, such as hydrogen chloride, sulfur dioxide, or nitrogen dioxide. A polymer layer whose electrical conductance changes under the effect of the gas to be determined is exposed to the gas mixture, and the electrical conductance, the electrical resistance, or the impedance of the polymer layer is determined. For the desorption of the gas to be determined, the polymer layer is heated at certain time intervals to a temperature above ambient temperature.

Abstract: A sensor element useful in making fluorescence-optical measurements includes a substrate having a carrier surface, particles having a large specific surface are which are glued, melted or sintered onto the carrier surface so as to provide small elevations of a regular distribution on the carrier surface, and an indicator substance immobilized on the particles. Additional substances can be applied to the particles to reduce undesirable influences of properties of the sample on the indicator substance.

Abstract: In an O.sub.2 sensor element which contains a fluorescent indicator substance, a polymerized silicone polymer is used as a carrier material in which the indicator substance is incorporated in solubilized form and in an at least approximately homogeneous distribution. Solubilization of the indicator substance may essentially be performed in analogy to Friedel-Crafts alkylation of aromatics, which will increase solubility of the indicator substance in the polymer carrier without affecting quenching behavior.

Abstract: Fluorescence-optical indicator material is chemically bonded in a network structure permeating a carrier membrane of the sensor element. As this network structure is independent of the membrane and not chemically bonded thereto, the properties of the membrane and the indicator are not affected by the immobilization.

Abstract: A new process for the manufacture of pyrono-condensed coumarin compounds by reacting an anil derivative of a heterocyclic compound with a cyanoacetic acid derivative in the presence of a base and a strong polar aprotic solvent is described.