Abstract: A pipette tip reloading system permits the reuse of a tip holder in a manner which interposes no additional transfer structure between the tip holder and the replacement tips. The reloading system includes a tip transfer tray and a push plate which releases the tips from the tray in a simple and reliable manner. The push plate also helps maintain alignment of the tips on the transfer tray as they are moved into position on the tip holder.

Abstract: A pipette tip reloading system permits the reuse of a tip holder in a manner which interposes no additional transfer structure between the tip holder and the replacement tips. The reloading system includes a tip transfer tray and a push plate which releases the tips from the tray in a simple and reliable manner. The push plate also helps maintain alignment of the tips on the transfer tray as they are moved into position on the tip holder.

Abstract: The ionization efficiency of a mass spectrometer is increased by creating a potential well between the electron source and the electron collector. The potential well is created by applying to the collector a reflection potential having an amplitude which is the same as or substantially the same as the amplitude of the potential applied to the electron source and a polarity which is the same as the polarity of the electron source potential. The potentials applied to the electron source and electron collector are relative to the ionization region effected between the source and collector. Many of the electrons produced by the electron source oscillate back and forth in the potential well thereby allowing those electrons a greater opportunity to interact with sample molecules to thus increase ionization efficiency.

Abstract: A quantity of electrons that will be used in the ionization event in an FTICR MS is preprogrammed. When the number of electrons produced reaches that number, the electron beam is turned off. This approach assures that the same number of electrons are used for every measurement and eliminates the variations due to fundamental characteristics of the electron sourcere and the variations in temperature due to changing ambient conditions.

Abstract: During operation of a FTICR MS the time after the opening of the pulsed valve sample gas inlet system that the peak of sample gas pressure occurs in the vacuum chamber is determined by measuring the amplitude of the ion pump current. The FTICR MS then uses that time and the known period of time for which a source of electrons used for an ionization event is energized to energize the electron source so that the known period of time includes the peak of vacuum chamber sample gas pressure. This allows ions to be created during the peak of the sample gas pressure to thereby obtain the maximum sensitivity during measurements.

Abstract: A pipette tip storage and dispensing system has a series of pipette tip holder cards each of which has a plurality of openings for holding a set of pipette tips extending partway through the openings in an upright orientation. The openings in each card match those in the other cards, and cards loaded with pipette tips can be stacked vertically with the pipette tips in one card extending into the open upper ends of the tips in the next adjacent card of the stack, to minimize storage space. An alignment device is arranged to hold the pipette tips in a card in a vertical orientation as the card is removed from the top of the stack and transferred to a pipette tip holder tray so that the pipette tips can be lowered into aligned openings in the holder tray with the card resting on the top wall of the tray.

Abstract: A 1,7-diacetylpyrazolotriazole was prepared by acid catalyzed acetylation of 6-methyl-3-[3-(4-nitrophenyl)propyl]-1H-pyrazolo[5,1-C]-1,2,4-triazole. Hydrolysis gave the 7-acetylpyrazolotriazole. Oxidation converted the 7-acetylpyrazolotriazole to a 7-acetoxypyrazolotriazole.

Abstract: A 1,7-diacetylpyrazolotriazole was prepared by acid catalyzed acetylation of 6-methyl-3-[3-(4-nitrophenyl)propyl]-1H-pyrazolo[5,1-C]-1,2,4-triazole. Hydrolysis gave the 7-acetylpyrazolotriazole. Oxidation converted the 7-acetylpyrazolotriazole to a 7-acetoxypyrazolotriazole.

Abstract: A constant energy drive circuit comprises two interconnected chopping circuits successively operable to control the current in a coil of an electromagnetic actuator. One chopping circuit operates during the rise time portion of the operating interval, the other operates beginning with the occurrence of a predetermined peak current and for remainder of the operating interval of fixed duration.

Abstract: A constant energy drive circuit for an electromagnetic print hammer has a chopping circuit including a comparator which cycles a switch connecting the energizing coil of the print hammer to an unregulated power supply. Changes in the drive voltage of the unregulated source are compensated for by altering the switching rate of the switch by adjusting the amplitude of a reference signal applied to the comparator. The reference signal adjustment is inverse to changes in the drive voltage.

Abstract: A pulse width modulated DC motor control system is designed to operate a DC motor at constant velocity. Feedback pulses generated at a rate proportional to the rotational velocity of the motor are converted to control pulses having a fixed on-time period which is independent of changes in the velocity of the motor. The control pulses are used to modulate a constant current source whose output is integrated to generate a sawtooth voltage signal whose average DC value is used as the basis of or pulse width modulating a DC voltage applied to the motor drive circuits of a DC motor.