Abstract: A cuvette for the measurement of the absorption of irradiation in liquid samples which at least in the regions of the windows is of a transparent plastic with an inner space which is formed in an essentially box-shaped upper part with an upper opening for filling and removing sample fluid and in an essentially box-shaped lower part which projects downwards from the floor of the upper part and which comprises a smaller cross section than the upper part, of maximally 200 &mgr;l content capacity, two pairs of planar-parallel windows in the lower part which lie opposite one another, wherein the distance a of the one pair is different to the distance b of the windows of the other pair in order to make available differing layer thickness of the sample fluid for the measurement and with four feet which are flush with the four corners of the upper part and which extend away from the upper part at least until up to the level of a floor of the lower part.

Abstract: A pipetting system with a pipetting device and at least one pipette tip releasably fastenable thereon, at least one fastening element on the pipetting device, on which the pipette tip is fastened, an ejection means on the pipetting device, which has an axially movable ejection element for releasing the pipette tip from the fastening element with an axial movement of the ejection element and a drive means for driving the axial movement of the ejection element, and a pull-means gear, push-means gear or linkage gear which transmits an essentially axial drive movement of the drive means into an axial movement of the ejection element and with which the ejection element at least on releasing the pipette tip from the fastening element is axially movable over a smaller distance than the essentially axial drive movement covers and an ejection force exceeding the force for the essentially axial drive movement can be exerted onto the pipette tip.

Abstract: A device for handling instruments used in technical cytological examinations has a holder base with at least two separate and moveable holders each carrying one instrument and each being coupled with a drive for switching the holders between two defined positions, one of which is a working position and the other is a rest position. In the working position, the distal end of the instrument located in the holder is aligned during a technical cytological intervention in the region of cellular material which is to be treated. In the rest position, the instrument held in the holder is kept at a safe distance from the cellular material which is to be treated. The drives are coupled with each other so that, when activated, they switch the holders between their rest and working position, respectively.

Abstract: An apparatus for electroporation stores a level of charge, specified by a user, on a capacitor, which is delivered to a cuvette through an optically isolated high voltage switch. The capacitor is charged through a charging system, including a current mode pulse width modulation control circuit, which monitors the current in the primary winding of a transformer and supplies a pulse width modulated signal, limiting the current on every pulse to a level set by the microcontroller, to the controlling transistor in order to generate the drive to the primary winding of the transformer. A controlled amount of energy is transferred through each pulse to the capacitor. The microcontroller monitors the voltage on the capacitor up to a threshold level to predict the number of pulses necessary to store the requested amount of charge on the capacitor. The microcontroller will then count the number of pulses until the number of pulses necessary to store the requested amount of charge on the capacitor has been reached.

Abstract: A magazine for pipette tip-shaped articles including a plurality of plates for holding the pipette tip-shaped articles and each having a plurality of bores for receiving the pipette tip-shaped articles in their entirety, a plurality of racks stacked over one another and adapted to each receive at least one holding plate, and complementary locking elements provided on the adjacent racks, respectively, and engageable with each other to form the at least one of a form-locking connection and a force-locking connection upon insertion of a holding plate in one of the adjacent racks and disengageable from each other upon removal of the holding plate.

Abstract: A method for the electropermeation of living cells between at least two electrodes over a predetermined interval with an electrical potential or a current, characterised by the following features:a voltage or current source which is not exhaustable over the interval is applied to the electrodes via a controllable power semiconductor functioning as a regulator;the course of the potential or of the current during the interval is predetermined by a setting value transducer which generates any selectable course of curve, and is inputted to a controller which is connected in front of the driver step for the power semiconductor;the controller receives a value, as an instantaneous value, corresponding to the actual potential or current applied at the electrodes;the interval has a time range of a few 100 ns to several minutes.

Abstract: A laboratory centrifuge has a centrifuge rotor supported on a stator and rotatable on a bearing about an axis of rotation. An electric motor drives the rotor and has pole pieces at a stationary part mounted on the stator and a rotatable part directly attached to the rotor, the stationary part having pole pieces with drive coils. The pole pieces magnetically act through a gap between the pole pieces and the rotatable part, and the gap lies in a surface which is perpendicular to the axis of rotation or forms a shallow frustocone opening either upwardly or downwardly.

Abstract: A closure vessel assembly for use in laboratory work within a range of temperature from -196.degree. C. to 100.degree. C. above zero includes a vessel made of a plastic material and having a wall defining the vessel mouth, and a closure for closing the vessel. The closure has an annular sealing lip which depends from the top wall of the closure and extends into the vessel mouth when the closure is locked on the vessel. The sealing surface of the sealing lip engages the sealing surface of the vessel wall, in the locked position of the closure with the vessel, to provide a seal therebetween. The respective radii of the sealing surfaces of the sealing lip and the wall are selected so as to provide for minimum surface pressure yet sufficient sealing between the sealing surfaces, despite any deformation of the materials of the sealing surfaces during the required closing time of the vessel.

Abstract: A cover receptacle assembly of plastics for use in laboratories, in particular for the polymerase chain reaction technique, comprising a tubular receptacle having a receptacle botton at one end and a receptacle opening at an opposite end, a cover for sealingly closing said receptacle opening, strap hinge means integrally and pivotally connecting said receptacle and cover with each other, and holding means for holding said cover in an intermediate position between an initial position wherein said cover is pivoted away from said receptacle opening for 180.degree. and a closing position wherein said cover closes said receptacle opening.

Abstract: Hand apparatus for pipetting and photometrically evaluating samples which comprise a pipetting means, an integrated photometer and a replaceable pipette tip connected to said pipetting means, said pipette tip being defined as a cell and provided within the optical path of the photometer for photometrically evaluating absorbed samples.

Abstract: A quantitative enrichment of volatile compounds from substances of the macro- to submicro field in a short time is realized by capillary distillation in a system which includes an evaporator vessel, on the bottom of which one or more filter plates are provided and which is connected to a condensing vessel by means of a capillary tube. The presence of filter plate(s) guarantees a uniform and constant boiling which facilitates the quantitative isolation of the volatile compounds.

Abstract: A manually pipette system including a replacement syringe having a mounting part and a plunger, a manual pipette having a space for receiving the syringe mounting part and a receiving body having a cavity for receiving the syringe plunger, with the mounting part and the plunger being movable into their attachment positions upon relative axial displacement of the syringe and the pipette, and syringe and plunger gripping levers for releasably securing the mounting part and the plunger in their attachment positions.

Abstract: The invention relates to a repetition pipette including a syringe receiving section for a mounting portion of a syringe, said pipette comprising a receiving member having a piston receiving portion for the mounting portion of a syringe piston, piston returning means for moving said receiving member away from said syringe receiving portion, piston advancing means for advancing said receiving member towards said piston receiving portion in steps corresponding to the liquid volumes to be ejected by the syringe, and step width adjusting means for adjusting the width of the steps of said receiving member by means of an adjustment element, characterized by constant step means for setting the width of the first step to a constant value independent of adjustments of said adjustment element for the widths of following steps.

Abstract: A repetition pipette including a syringe receiving section for the mounting portion of a syringe, a receiving member having a piston receiving portion for the mounting portion of a syringe piston, piston returning means for moving said receiving member away from said syringe receiving portion, piston advancing means for advancing said receiving member towards said piston receiving portion, which piston advancing means comprises a rack connected to said receiving member, and actuating element movable along an actuation path, and a pawl pivotally mounted thereto, which pawl is moved into engagement with the toothing of the rack so as to drive the latter for an advancing step when the actuating element is advanced, and is moved out of engagement with the rack when the actuating element is returned, and step width adjusting means for adjusting the step width of the advancing step, the step width adjusting means comprising a withholding element displaceable along the rack by means of an adjusting element for preve

Abstract: A system for centrifugation of samples includes at least one carrier, which is provided with a plurality of elements connected with each other by joints and having each an uptake for receiving a sample to be centrifuged, and a rotor for supporting the carrier, with the elements being arranged, in a centrifuged position of the elements, along a circle having its center lying on the rotational axis of the rotor.