Glass pipette

Dry heat sterilisation is used for equipment that can withstand high temperature and dry heat but cannot withstand wet or steam autoclave. This method is often used for glassware as it dries and sterilises in one operation. The pipets must be wrapped in dustproof aluminum foil or placed in metal pipette cans. The can lids are removed during heating and replaced after sterilisation, that is before any dust can get in the can. Disposable items are not recommended for dry heat sterilisation. This method may only be good for permanent reusable glass pipettes. 

The silanization of the surface of a glass pipette may be necessary for different reasons [19]. If the pipette is to be filled with an aqueous solution, its outer wall should be made hydrophobic to prevent the formation of a thin aqueous film that may cause large deviations of the experimental diffusion-limiting current from the theory (see Section II.B). Experimental voltammograms were found to quantitatively agree with the theory after the aqueous layer was eliminated by silanizing the outer pipette wall. 

Fig. 4.3.1 (a) Photographs of a tubeless siphon formed by dissolving 0.5%w/v poly (ethylene oxide) powder in tap water, where a Fano column can be seen between the tip of the glass pipette at the top and fluid reservoir at the bottom, (b) Excess fluid can be seen just below the fluid entrance, (c) A large amount of excess fluid eventually flows downwards outside and along the Fano column, which can disturb the vertical location of the column. These figures illustrate the fact that there is an optimum volume flow rate for a particular flow system. 

Velocity images and profiles at several selected heights are shown in Figure 4.3.6, where the noisy points in the images indicate the air space where a liquid signal was not detected. When the fluid is inside the glass pipette, the velocity profile is nearly Poiseuille and a non-slip boundary condition is almost achieved. This is consistent with one of the early tube flow reports that the 0.5% w/v solution of... 

Pull a glass pipette tip (10 pL Drummond Microdispenser 100 replacement tubes, Broomall, PA, Cat. 3-000-210-G) using a one-stage magnetic puller with a heating element. 

Fill the glass pipette with mineral oil (dyed with 4-amino-3-nitrotoluene MP Biomedicals, Irvine, CA, Cat. 154757) to check that the tip is patent. 

Attach the glass pipette to a microdispenser (10 pL digital, Drummond, Broomall, PA, Cat. 3-000-510-X), and mount the microdispenser onto a micromanipulator. 

Under a microscope, carefully draw the transcript solution droplet (placed on Parafilm) into the microinjector tip. (It is essential to avoid drawing air bubbles into the glass pipette tip, as these will interfere with RNA injection.)... 

Another inadvertent exposure also occurred on a Friday, but not at Edgewood. The daughter of the Commander at Deseret Station, a small post in Utah, was working as a lab technician for the summer. Shortly before quitting time, while transferring solutions, she accidentally drew in a small amount of BZ solution from a glass pipette. 

Figure 3.25 — Electrolytic flow-cell of the tubular type. (A) Whole cell. (B) Detail of working micro-electrode 1 Working electrode 2 reference electrode (Ag/AgCl) 3 counter-electrode (Pt wire) 4 acrylic tube 5 rubber cup 6 electrolyte solution (mobile phase) 7 fused-silica tube (50- or 100-/tm ID) 8 Ni wire (diameter 25 or 50 im, length 5 mm) 9 PTFE tube (0.1-mm ID, 2-mm OD) 10 hole 11 adhesive resin 12 glass pipette 13 silver paste 14 insulator 15 electric wire, (Reproduced from [184] with permission of Elsevier Science Publishers).

Remove the upper hexane phase with the aid of a glass pipette attached to a water pump. 

Dry the glass equipment (i.e., NMR sample tube without plug and glass pipettes) for 2 hr in an 100°C oven. 

Using a finely drawn glass pipette with a diameter slightly larger than an oocyte. Wash the oocytes through the 150 xL media drops to remove cumulus cells and sperm. 

Figure 12.1 illustrates the main structure of a nephron [1], The measurements to be reported in this chapter were performed on rats. A rat kidney contains approximately 30000 nephrons as compared to the one million nephrons in a human kidney. The process of urine formation starts with the filtration of plasma in the glomerulus, a system of 20-40 capillary loops. The presence of a relatively high hydrostatic pressure in this system allows water, salts and small molecules to pass out through the capillary wall and into the proximal tubule. Blood cells and proteins are retained, and the filtration process saturates when the protein osmotic pressure balances the hydrostatic pressure difference between the blood and the filtrate in the tubule. For superficial nephrons, the proximal tubule is visible in the surface of the kidney and easily accessible for pressure measurements by means of a thin glass pipette. 

As a reminder, pipettes are classified either TD (to deliver) or TC (to contain). The TD pipettes are the more common of the two. With a TC-type pipette, the residual contents in the pipette must be extracted by repeated washing. Always read the label of a glass pipette to determine if it is TD or TC. 

If your laboratory no longer employs glass pipettes, use only the automatic plastic type in this experiment. 

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