Disc detector

The disc detector originally developed by Dubsky [21] employed a rotating gauze disc as a carrier and a diagram of the device is shown in figure 14. It consists of a rotating disc the perimeter of which is... 

A microwave-heated platinum disc detector has been used in a capUlary-electrophoresis arrangement [59]. A gold disc electrode with indirect electric heating worked as a detector in micro-capillary electrophoresis [60]. Dopamine and catechol were determined successfully. In a similar arrangement, the catalytic activity of copper for detection of shikimic acid and carbohydrates was utilised with an indirectly heated copper disc electrode [40]. 

Many errors can arise in the procedure used for this experiment. The measured weight of the foil disc detectors could involve a large error. The technique used to calibrate the counters for measuring the detector activity could be refined to give more accurate results. Careful analysis of the results would, of course, be a lengthy task in itself it is suggested that each student try to examine the more prominent errors that could have arisen and why there are any deviations from the expected theoretical results. 

The client insisted on a test. The smoke detectors worked, and the explosive charge operated, but the cutter did not cut the rupture disc. The explosive charge could not develop enough pressure because the volume between it and the rupture disc was too great. The volume had been increased as the result of a change in design installation of a device for discharging the halon manually. 

The diffraction pattern obtained in the detector plane when the beam scan in a STEM instrument is stopped at a chosen point of the image comes from the illuminated area of the specimen which may be as small as 3X in diameter. In order to form a probe of this diameter it is necessary to illuminate the specimen with a convergent beam. The pattern obtained is then a convergent beam electron diffraction (CBED) pattern in which the central spot and all diffraction spots from a thin crystal are large discs rather than sharp maxima. Such patterns can normally be interpreted only by comparison with patterns calculated for particular postulated distributions of atoms. This has been attempted, as yet, for only a few cases such as on the diffraction study of the planar, nitrogen-rich defects in diamonds (21). 

Miniaturisation of scientific instruments, following on from size reduction of electronic devices, has recently been hyped up in analytical chemistry (Tables 10.19 and 10.20). Typical examples of miniaturisation in sample preparation techniques are micro liquid-liquid extraction (in-vial extraction), ambient static headspace and disc cartridge SPE, solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE). A main driving force for miniaturisation is the possibility to use MS detection. Also, standard laboratory instrumentation such as GC, HPLC [88] and MS is being miniaturised. Miniaturisation of the LC system is compulsory, because the pressure to decrease solvent usage continues. Quite obviously, compact detectors, such as ECD, LIF, UV (and preferably also MS), are welcome. 

FTIR spectra were collected with a Nicolet 740 spectrometer and a custom built in situ gas flow cell. The spectrometer was equipped with a MCT-B detector cooled by liquid nitrogen. Approximately 15 mg of the MgO catalyst sample was pressed into a self-supported disc and placed in a sample holder located at the center of the cell. The temperature in the cell was measured with a thermocouple placed close to the catalyst sample. Transmission spectra were collected in a single beam mode with a resolution of 2 cm 1. Prior to introduction... 

Protection of the Detector. With all direct calibration methods the primary beam intensity must be measured. If the primary beam itself is attenuated, shape of the beam and spectral composition of the radiation may be altered. This problem is avoided if the load of the detector is reduced by scanning the beam using a slit or a perforated disc. On the other hand, in order to be useful at a powerful synchrotron beamline these devices should have very tiny and well-defined slits or holes. 

There are two detection sensitivities that are of interest for characterizing the BioCD performance. The first is a metrology sensitivity that includes experimental noise sources such as the laser intensity fluctuations and detector noise, but does not include variability of the protein spots on the disc. The second detection sensitivity is under actual assay conditions in which antibody spot variability plays a dominant role. For both of these sensitivities, it is important to define a scale-free sensitivity that is an intrinsic property of the detection platform. 

The Hewlett-Packard HP 1049A Electrochemical Detector cell has a unique system for working electrode replacement the working electrode itself (an 8 mm diameter disc) can be removed from its holder, allowing for economic working electrode replacement in case the working electrode surface cannot be restored. 

Ch - chopper disc, Fhl - filter holder, D - iris diaphragm and interchangeable pinholes of various sizes, Sch - sample chamber, S - sample holder, ID - iris diaphragm, L2 - receiver lens, Ph2 - detector photomultiplier, A - measuring arm, Fh 2 - filter holder, Phi - detector photomultiplier... 

High Molecular Weight Polymers in Cyclohexane and also in Special Column Arrangements. Waters Associates Ana-Prep and 501 GPC were used. One four-foot Styragel column of 5x10 pore size was connected to a pump and a differential refractometer detector to determine the effect of fritted discs on degradation. 

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