Sealing glass capability

The arrangement is then placed in a furnace, heated to 800°C, and the pressure decay test is repeated. The setup can be subjected to thermal cycles with pressure decay tests at room temperature and at 800°C. A good hermetic seal, however, will not show any pressure decay at a low pressure differential. The results of one series of tests using a glass composite material that has a glass transition temperature (Tg) of about 700°C, at 5 psi are shown in Figure 5.10. The combination of pressure and thermal cycle tests showed that the seal is capable of withstanding the pressure... 

A new analytical procedure, termed TMAH thermochemolysis, has been used to assess the structure characterization of HS from a variety of samples. Although this procedure has mainly been performed in pyroprobe units at pyrolysis temperatures, it can also be conducted at subpyrolysis temperatures in sealed glass tubes. Therefore, this procedure can be easily implemented in any laboratory having gas chromatographic capabilities, in contrast to other chemolytic or pyrol c procedures. This is a potentially valuable advantage, because it makes the technique readily available to most geochemical laboratories. 

Apparatus. All reactions with aqueous reagents must be carried out in closed systems capable of withstanding pressure. For this reason most reported experiments have been limited to runs with small amounts, usually 1 to 4 g. of ketone, in sealed glass tubes. Most procedures at present call for temperatures below 180° at temperatures of 160-180° the pressures developed in sealed tubes seldom appear to be dangerously high it has been estimated that at 230° the pressure may reach as hi a value as 41 atmospheres. When the tubes are opened there is little residual pressure, and sometimes air is drawn into the tube. However, it is advisable to observe the precautions usual in such work. 

A test method to evaluate the shear stress capability of a seal material is reported [36], An electrolyte-anode-electrolyte trilayer was glass sealed to two metal interconnect plates as shown in Figure 5.11. Shear testing was done in two different modes, constant loading rate and constant displacement rate, to determine the shear modulus and viscosity. 

The planar chips used by the PatchXpress, QPatch, and Patchliner systems incorporate a glass-based substrate that permits the formation of GQ-level seal resistances between the cells and the plate. Consequently, the noise level on these systems tends to be low and they are thus capable of distinguishing small ionic currents (<100 pA) reliably. Their planar chips contain 8, 16, or 48 wells with a single aperture in the center bottom position of each well. These systems permit parallel recordings from several individual cells on the chip. However, due to variation in the performance of randomly selected cells, only a proportion are expected to complete any given experimental protocol and so the capacity to acquire pharmacology data may not match initial expectations (Xu et al. 2003). 

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