Abstract: A permanently united plate heat exchanger normally comprises a plate package (1) having two end plates (3, 4) and several heat transferring plates (5) which are arranged therebetween. The end plates (3, 4) and the heat transferring plates (5) are permanently united, for instance by brazing, to a plate package the end plates of which have altogether four openings to form inlets and outlets for two heat exchange fluids. Two or more plate packages (1, 2) may be coupled together to form a plate heat exchanger. Preferably, plate packages of this kind are produced which have different numbers of heat transferring plates (5, 8).

Abstract: A method and apparatus for non-invasive measurement of blood glucose concentration based on producing a polarized-modulated laser beam via a polarizing frequency shifter (24), measuring a phase difference introduced, e.g., by a finger (F) or a ear lobule (E) of a subject, measuring phase difference between a reference signal (SR) and a probe signal (SP), and processing the obtained data which are then presented as blood glucose concentration. The apparatus for the above-mentioned measurements comprises an infrared laser source (22), a polarized frequency shifter (24) which produces a polarized-modulated infrared laser beam, a piezoelectric transducer (26) for driving the polarizing frequency shifter (24), and an optical transducer (30) with a glucose measuring head (32). The latter has an optical input for receiving the laser beam and a balanced receiver (62).