Bubble recording

Turn on the hot plate and heat the water bath slowly. Record the boiling point when the liquid begins to boil in Data Table 1. There should be a steady stream of bubbles. Record the temperatures to one place after the decimal point. 

The data in Fig. 7.1 cover the period during which reliable analytical techniques have been in use. In order to extend the record further into the past, resort is made to measurements obtained using cruder techniques (by modern-day standards) in the latter part of the f 9th century and the first half of the 20th century. These early data are shown in Fig. 7.2, together with the most complete recent dataset, which is from Mauna Loa. A more reliable way of extending the record backwards has been through the extraction and analysis of bubbles of air trapped in ice cores collected from the polar ice-caps. The principle of this method is that the trapped air bubbles record the atmospheric composition at the time the ice formed. By dating the various layers in the cores from which the air bubbles have... 

FIGURE 7.20. (a) A viscous bubble is formed by injecting air in ultra-viscous PDMS it thins down by way of a draining process (b) bursting and death of the bubble recorded with an ultra-high-speed camera. (FVom G. Debregeas, P. G. deGennes, and F. Brochard, in Science, 279, p. 1704 (1998). 2001 American Association for the Advancement of Science. Reproduced by permission.)... 

Transfer a few crystals (or powder or oil) of retinal, 1-10 mg as required, into a test tube. Dissolve the retinal in about 1 mL of methanol or ethanol (the reduction reaction does not occur efficiently in nonhydroxylic solvents such as hexane or acetonitrile). Dilute this solution (for example, touch the retinal solution with a Pasteur pipet, and then immerse the pipet in about 1 mL of methanol) and scan its absorption spectrum, diluting or concentrating this solution as necessary to obtain a representative spectrum (A, ax 370-380 nm, Fig. 6). Add a small quantity (typically 10-25 mg, need not be exact) of sodium borohydnde to the concentrated-retinal solution, and shake the solution gently. The reaction should be rapid. Note the change in color from bright yellow to pale yellow and the rapid evolution of H2 bubbles Record the absorption spectrum. If the absorbance maximum is at 325 nm and the spectrum is characteristic of retinol as shown m Fig. 6, the reduction of retinal to retinol is complete. 

Prepare in water two dilutions of standard preparation containing 2-0 and 14 units per ml together with two similar dilutions of the unknown. Place 1 ml of each dilution into a 6" x test-tube followed by a quantity of thrombokinase solution (about 0-2 ml) sufficient to cause coagulation in the 2u/ml standard tube in about ten minutes after the addition of 1 ml of sulphated whole blood. Add 1 ml of sulphated whole blood to each tube, mix gently avoiding the formation of air bubbles. Record to the nearest fifteen seconds the time for the formation of a firm clot which remains in the bottom of the tube when it is inverted. 

The oil and gas samples are taken from the appropriate flowlines of the same separator, whose pressure, temperature and flowrate must be carefully recorded to allow the recombination ratios to be calculated. In addition the pressure and temperature of the stock tank must be recorded to be able to later calculate the shrinkage of oil from the point at which it is sampled and the stock tank. The oil and gas samples are sent separately to the laboratory where they are recombined before PVT analysis is performed. A quality check on the sampling technique is that the bubble point of the recombined sample at the temperature of the separator from which the samples were taken should be equal to the separator pressure. 

A substance which commences to soften and pull away from the sides of the capillary tube at (say) 120, with the first appearance of liquid at 121° and complete liquefaction at 122 with bubbling, would be recorded as m.p. 121—122 (decomp.), softens at 120. ... 

A third fundamental type of laboratory distillation, which is the most tedious to perform of the three types of laboratory distillations, is equilibrium-flash distillation (EFV), for which no standard test exists. The sample is heated in such a manner that the total vapor produced remains in contact with the total remaining liquid until the desired temperature is reached at a set pressure. The volume percent vaporized at these conditions is recorded. To determine the complete flash curve, a series of runs at a fixed pressure is conducted over a range of temperature sufficient to cover the range of vaporization from 0 to 100 percent. As seen in Fig. 13-84, the component separation achieved by an EFV distillation is much less than by the ASTM or TBP distillation tests. The initial and final EFN- points are the bubble point and the dew point respectively of the sample. If desired, EFN- curves can be established at a series of pressures. 

Press the button on the electronic bubble meter. Visually capture a single bubble and electronically time the bubble. The accompanying printer will automatically record the calibration reading in liters per minute. 

For either type pump, the bubble should stop between the 95 cc and 105 cc marks. Allow 4 minutes for the pump to draw the full amount of air. Also check the volume for 50 cc (1/2 pump stroke) and 25 cc (1/4 pump stroke) if pertinent. A +5 percent error is permissible. If error is greater than +8 percent, send the pump for repair and recalibration. Record the calibration information required on a calibration log. It may be necessary to clean or replace the rubber bung or tube holder if a large number of tubes have been taken with the pump. 

It should be pointed out that Eq. (10) can correctly represent experimental results (cited papers recorded reasonable agreement between theory and experiment) only when diffusion of gas from bubble to bubble can be ignored. When the bubble is small, surface Laplace pressure PL P, and coalescence of bubbles occurs in such a way as to make the volume of the resul tant bubble greater than the sum of the original bubble volumes [27]. 

A fiber-diffraction pattern is recorded on a flat-film camera in which the fiber-to-photographic film distance is typically in the range of 3 to 4 cm. During exposure to X-rays, the specimen chamber is continuously flushed with a slow and steady stream of helium gas that has been bubbled through a saturated salt solution so that (a) the fiber is maintained at a constant desired r.h. and (b) fogging of the photographic film from air scattering is reduced. 

Multiple options for data input, the most important of which are machine read and thus obviate the bottleneck that often occurs in data entry. The two main options are Optical Mark Read (bubble) forms, and Smart-Pen , a special pen with an optical sensor that records each keystroke (Fig. 23.2). Both utilize paper case report forms, for which sites have indicated a strong preference over the requirement to enter data on a keyboard. 

Spectroelectrochemical Cell Figure 5.4 shows spectroelectrochemical cells used in electrochemical SFG measurements. An Ag/AgCl (saturated NaCl) and a Pt wire were used as a reference electrode and a counter electrode, respectively. The electrolyte solution was deaerated by bubbling high-purity Ar gas (99.999%) for at least 30 min prior to the electrochemical measurements. The electrode potential was controlled with a potentiostat. The electrode potential, current, and SFG signal were recorded by using a personal computer through an AD converter. 

The bubble behavior near the boiling crisis is three-dimensional. It is hard to show a three-dimensional view in side-view photography, because the camera is focused only on a lamination of the bubbly flow. Any bubbles behind this lamination will be fussy or even invisible on the photograph, but they can be seen by the naked eye and recorded in sketches as shown in Section 5.2.3. For further visual studies, the details inside bubble layers (such as the bubble layer in the vicinity of the CHF) would be required. Therefore, close-up photography normal and parallel to the heated surf ace is highly recommended. 

Cumo et al. (1969) reported that the pressure effect on the bubble diameter is linear in a Freon-114 flow, as shown in Figure 5.43. They tested the two-phase Freon-114 flow in a vertical rectangular test section at a mass flux of 100 g/cm2 s (0.737 x 106 lb/ft2 hr). The average bubble diameters at various system pressures were obtained from high-speed photographic recordings. The effect of reduced pressure, p pci, on the average diameter of Freon bubbles is correlated as... 

Janssen and Hoogland (J3, J4a) made an extensive study of mass transfer during gas evolution at vertical and horizontal electrodes. Hydrogen, oxygen, and chlorine evolution were visually recorded and mass-transfer rates measured. The mass-transfer rate and its dependence on the current density, that is, the gas evolution rate, were found to depend strongly on the nature of the gas evolved and the pH of the electrolytic solution, and only slightly on the position of the electrode. It was concluded that the rate of flow of solution in a thin layer near the electrode, much smaller than the bubble diameter, determines the mass-transfer rate. This flow is affected in turn by the incidence and frequency of bubble formation and detachment. However, in this study the mass-transfer rates could not be correlated with the square root of the free-bubble diameter as in the surface renewal theory proposed by Ibl (18). 

Figure 29 (Qin and Liu, 1982) shows the behavior of individual particles above the distributor recorded by video camera of small clusters of particles, coated with a fluorescent material and spot-illuminated by a pulse of ultra violet light from an optical fiber. The sequential images, of which Fig. 29 just represents exposures after stated time intervals, were reconstructed to form the track of motion of the particle cluster shown in Fig. 30. Neither this track nor visual observation of the shallow bed while fluidized, reveal any vestige of bubbles. Instead, the particles are thrown up by the high velocity jets issuing from the distributor orifices to several times their static bed height.

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