Prototype Chamber

A prototype hexcell chamber is under construction at SLAC. This prototype will be used to test the electrostatic stability and tracking resolution of the current cell design, as well as to provide valuable experience in design and fabrication of the feedthroughs. 

The electrical contact between the sense wire and preamplifier is provided by jacks pushed onto the aluminum tubes on the feedthroughs. These jacks are soldered into preamplifier PC boards, with one PC board connecting all wires for 4 cells (4 sense wires and 22 field wires). A preamplifier board may be plugged or unplugged as a 4-cell unit. The preamplifiers will be mounted on the backward end of the chamber only, leaving the forward end of the chamber free of electronic components and signal cables to minimize the amount of scattering material in the forward direction. 

Signals from the preamp boards on the chamber are fed into postamplifier modules located near (but not on) the chamber. I he output signals from the postamps are routed to the data acquisition modules in the counting house . Calibration signals can be applied under computer control to the preamplifier boards. 

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Creep studies for tlie 55 /iin aluminum wire have been made in the prototype chamber as shown in Figure 3.12. ASME 5056 aluminum has less creep than ASME 6061. The measurements indicate that 5056 aluminum can be used at a tension of 50 g. We will continue the long term study. 

Figure 3.13 shows a test setup of several such preamplifier boards that have been constructed for the prototype chamber. These boards use the Mark II preamplifier circuit. The actual PEP-II electronics will use more modern circuitry, yielding a reduction in the size of the PC board. 

A small 3 cm x 3.5 cm section of the catalyst-coated desiccant wheel (25 cm diameter) was cut and placed in specially made holder shown in Fig. 12.9-6a. The piece of sample was tested in a 0.2 m3 environmental chamber at Chiaphua Industries Ltd. (Fig. 12.9-6b) for reduction of airborne VOC. The chamber was filled with the target VOCs through two stage saturators shown in Fig. 32b. Once the VOC level in the chamber stabilized, the fan was turned on to circulate the air through the sample. Three sets of sensors were located at the inlet and outlet of the holder, as well as in the center of the chamber. The chamber temperature and relative humidity were kept constant during the test. Figure 12.9-6c shows the results for VOC levels of 4000, 2000 and 1000 ppb at room temperature. The reduction rate was slower because of the low VOC concentration and the poor air circulation in the chamber. Also unlike the Prototype Unit, the catalyst was kept at room temperature throughout the test. 

Figure 12.9-6. A small prototype unit (a) consists of a fan and coated monolith was placed in a test chamber shown in (b) and tested for VOC removal at ambient conditions, (c) The results show that the VOC level was decreased by half in less than an hour.

The test results in Fig. 12.9-10 show a clear and immediate reduction in airborne bacteria when the Prototype Unit was turned on. Ninety percent reduction of B. subtilis, P. aeruginosa and S. epidermidis were reached at 1.5, 10 and 3 minutes of Prototype operation, respectively. The control experiments showed fluctuations due to poor circulation within the test chamber, but otherwise maintained a bacteria level higher than when the Prototype Unit was in operation. 

SEMATECH estimated that the 5-year cost of operation for the prototype unit abating four-chamber exhausts containing PECs was 83,000/ year based on an 83% TPU operation while the commercial TPU cost of operation was 77,000/ year based on 100% TPU operation. The scrubber s once-through waster usage of 8 gal/min represents the major utility cost. It was assumed that a commercial facility would have lower electrical costs by eliminating the booster pump and extra sump pump (D17789D, pp. 9, 44). Table 1 discusses the annual utility costs associated with the industrial unit. 

This design practically or to a considerable extent eliminates particles collisions in the separation zone, which sharpens separation. As the flow field in the chamber has no inherent vortexes the device has lower air resistance and energy consumption. Several prototypes of this classifier were used in phosphate industry for separation of crushed phosphate ore at 1 mm cut size. One such plant with output of 251 per hour and pressure drop of 800-900 Pa yielded 96-98% cleanness of fines and 78-85% of coarse fraction [8],... 

In a later generation of fluidized bed classifiers the feed is poured onto the grid from above (Fig. 3c, d), so crushing is eliminated [9], Several prototypes of such fluidized bed classifiers with cylindrical or conical chambers of diameter 350-1700 mm and throughput of 0.5-10 t/h, were constructed for separation of sand, potassium chloride and ground phosphate particles with sizes from 50 to 1.5 mm [10], The recovery of coarse fraction was 75-92%. 

Basically, harvest of invasive cells after any invasion assay (see Chapter 4) can be used to select a cell population with increased invasive ability. Poste et al. (1980) have used the chorioallantoic membrane (CAM) assay, a canine blood vessel perfusion-invasion chamber, or retrograde injection of tumor cells in the mouse bladder, to select tumor cell variants with respect to their invasive ability. B16-BL6 melanoma cells, widely used as a prototype of highly invasive metastatic cells have been subjected to six rounds of selection with the bladder system. The application of these three systems for selection is described in detail in the original paper (Poste et al., 1980), and will not be treated further here. 

Careful examination of Fig. 3 reveals that the disk and its spindle connector would need to be made in two parts to enable the assembly of this prototype. A slightly larger access where the bonnet connects would enable a composite disk and spindle to be inserted from above. However, the spindle needs to be able to pivot within the disk mounting to enable the three-dimensional fluid forces to tilt the disk without causing excessive friction in the spindle-lift guides. Nevertheless, assembly would be simpler where the disk is inserted from above, and any reduction in diameter (and hence material) confined to the spring chamber. 

So, scientists from both traditions devised techniques to mimic, but not imitate perfectly, phenomena found outside of the laboratory. The difference between these two traditions centers on the prototypes used as the source of instrumental techniques. The nineteenth-century meteorologists used observable atmospheric conditions as the prototype for the dust chamber, while Thomson and his colleagues used the unobservable qualities of fundamental particles to define the electron. 

The next stage was achieved in 1967 by Updike and Hicks, who entrapped GOD in a gel of polyacrylamide, thus increasing the operational stability of the enzyme and simplifying the sensor preparation. Further investigations by Reitnauer (1972) enabled the successful application of an enzyme electrode in a prototype blood glucose analyzer. In 1975 Yellow Springs Instrument Co. (USA) commercialized a glucose analyzer (model 23 A) which was based on a patent by Clark (1970). The Lactate Analyzer LA 640 by La Roche (Switzerland) followed one year later. In this instrument the enzyme is dissolved in a buffer in a reaction chamber placed in front of the electrode. 

It is possible that inorganic cell prototypes were created in hydrothermal systems. Iron sulfides are abundant in oceanic hydrothermal systems and are one of the main products of high-temperature vents. Russell and Hall (1997) and Martin and Russell (2003) proposed that iron monosulfide bubbles, created in an oceanic hydrothermal setting formed a template for the structure of the first cells. In this model the FeS membrane acted as a catalytic chamber within which organic synthesis could take place. As this process evolved, the sulfide membrane became coated with abiotic organic polymers which eventually took over from the sulfide and replaced their function. 

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