Sliding bubbles

In the bubble formation from an inclined surface, however, the bubble development and the bubble detachment processes are decoupled because a developing bubble could drift out of the orifice due to the component of the buoyancy parallel to the inclined surface. Once a sessile bubble drift out of the orifice, the bubble development ceases because no air is fed into a sliding bubble. Since the bubble development and detachment are decoupled, the flow rate of air becomes an important factor, which controls the frequency of sliding bubble... 

While the interfacial tension and the buoyancy of the bubble determine the sliding speed of an attached bubble, the flow rate of air determines the frequency of creating a sliding bubble. Figures 27.12 and 27.14 show the influence of the flow rate of air on the detachment of sliding bubbles on the surface. In the case shown in... 

Figure 27.14 Effect of the flow rate on two drifted bubbles on the surface detachment of a bubble by emerging two sliding bubbles tilt angle 45 degree, contact angle of water 62.3 degree, orifice diameter 0.55mm, air flow rate 4.76ml/m (bubble volume 0.024ml/bubble).

A horizontal surface is best for small-bubble formation. A tilted surface with multiple holes increases the probability of bubbles merging. Creation of sliding bubbles should be avoided. Therefore, a flat horizontal surface is best for creating many small bubbles. 

Son, G. (2001) Numerical study on a sliding bubble during nucleate boiling, KSME International Journal, Vol. 15, pp. 931-940. 

The above analyses assume that the bubble remains in position above the nucleation site from which it arose. However, bubbles may slide along the surface without being released from it and continue to grow during this process. This phenomenon is discussed by Cornwell [54], and observations on sliding bubbles on inclined planes and curved surfaces (carried out using liquid crystal thermography and... 

K. Cornwell, The Role of Sliding Bubbles in Boiling on Tube Bundles, Proc. 9th Int. Heat Transfer Conference, Jerusalem, Israel, vol. 3, pp. 455-460,1990. 

The solid line in Fig. 4.48 denotes the calculated value for A = 1. Clearly, this line is not satisfactory for predicting the boundary between the sessile bubble regime and the sliding bubble regime. The value of k giving the best fit to the boundary was found to be 2, as demonstrated by the broken line in Fig. 4.48. 

Foam formation in a boiler is primarily a surface active phenomena, whereby a discontinuous gaseous phase of steam, carbon dioxide, and other gas bubbles is dispersed in a continuous liquid phase of BW. Because the largest component of the foam is usually gas, the bubbles generally are separated only by a thin, liquid film composed of several layers of molecules that can slide over each other to provide considerable elasticity. Foaming occurs when these bubbles arrive at a steam-water interface at a rate faster than that at which they can collapse or decay into steam vapor. 

Bubble growth occurs rapidly and is followed by a period when the bubbles radius remains relatively constant. Bubbles do not grow and collapse on the wall, but start to slide away from their nucleation sites almost immediately after nucleation. 

Bubbles later eject into the flow for subcooling below 60°C (108°F). Bubbles become elongated as they slide on the wall and condense while sliding along the wall. These bubbles are shaped like inverted pears, with the steam touching the wall just prior to ejection. 

Newtonian liquid viscosity, U is the bubble velocity, and aQ is the equilibrium surface tension), where surface tension and viscous forces dominate the bubble shape (15). Using a lubrication analysis, Bretherton established that the bubble slides over a stationary, constant-thickness film whose thickness divided by the radius of the tube, h R., varies as the... 

Grasp one end of a dust-free 22 mm X 40 mm microscope glass coverslip with forceps. Lower one end near the cDNA probe until it touches the surface outside the printed area and slowly lower the opposite end of the coverslip onto the slide. The solution will spread across the entire print area beneath the coverslip. Use a yellow tip to carefully adjust the position of the coverslip over the printed area. Large air bubbles can be moved away from the hybridization area by a gentle tapping on the coverslip with a yellow tip. Small air bubbles will be released during hybridization. 

Withdraw the slide immediately or wait a few seconds to derive a thicker emulsion layer (DO NOT dip each slide repeatedly to achieve a thicker emulsion instead, reduce withdrawal rate or emulsion temperature). Consult Rogers (7) for selecting an appropriate emulsion thickness (1.5-2.0 pm but depends on emulsion and isotope in question), especially if one is contemplating quantitative autoradiography. Move slide away from the emulsion so that excess emulsion does not drip back onto the surface of the emulsion creating bubbles. 

To each slide, apply one or two drops of non-aqueous mounting medium to the uncovered tissue and apply the coverslip. Apply the coverslip at an inclined angle to the slide, and lower it gently to avoid trapping air bubbles. 

Apply the coverslip at an inclined angle to the slide and lower it gently to avoid trapping air bubbles. 

Mount and coverslip Mount slides using clean cover slips and dry overnight. Slides can be cleaned the following day using xylene or chloroform. Remember, it is important to remove all bubbles from under the cover slip. Be conservative with the amount of Permount used in mounting, as using too much can obstruct the view of the sections under a microscope. 

Cover a region of a slide and a region of a coverslip with 40 pL of hybridization buffer, and mate the two, ensuring that no air bubbles are entrapped. 

With a soft paint brnsh gently remove water bubbles and foldings of the tissue. After mounting sections to the slides, allow to air-dry. 

Make sure that there are no air bubbles. I usually place 40-50 pL PCR reaction mix on the top of the coverslips. Invert one slide at a time, touch it to the drop of reaction mix, and quickly lift the slide. The coverslip should remain adhered to the slide because of surface tension. Flip the slide, center the coverslip with a clean pipet tip, and gently remove the air bubbles. 

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