Manual dipping

Fig. 38 Companson of manual dipping (A) with mechanized dipping (B) on the basis of scans and calibration curves [114] — 1 = cM-diethylstilbestrol, 2 = traw-diethylstilbestrol, 3 = ethinylestradiol Scanning curve 2 ng of each substance per chromatogram zone = 313 nm, /n > 390 nm Dipping solution water — sulfuric acid — methanol (85 + 15 + 1)...

The advantage of such dipping apparatus is that the insertion and removal of the chromatogram is performed at a uniform speed and the time of immersion can be set as necessary. Interfering ripple marks", such as are observed on manual dipping, do not occur. Care must be taken, however, to clean off the back of the... 

The first electrodeposition of a compound superlattice appears to have been by Rajeshwar et al. [219], where layers of CdSe and ZnSe were alternately formed using codeposition in a flow system. That study was proof of concept, but resulted in a superlattice with a period significantly greater then would be expected to display quantum confinement effects. There have since been several reports of very thin superlattices formed using EC-ALE [152, 154, 163, 186], Surface enhanced Raman (SERS) was used to characterize a lattice formed from alternated layers of CdS and CdSe [163]. Photoelectrochemistry was used to characterize CdS/ZnS lattices [154, 186]. These EC-ALE formed superlattices were deposited by hand, the cycles involving manually dipping or rinsing the substrate in a sequence of solutions. 

Spraying, dipping, and mechanical-roll coaters are generally used on large production runs. Dipping is also used to cover large areas quickly. Areas that do not require adhesive can be masked off. Manual dipping is often effective and baskets, screens, and perforated drums are available to facilitate immersion of the part into the adhesive bath. 

Equipment for dipping TLC plates can be obtained in various forms. Until recently, dipping chambers suitable for manual dipping of 10 x 10 cm, 20 x 10 cm and 20 x 20 cm plates were often used. However, instructions in personal terms such as brisk , rapid or careful dipping cannot usually be exactly duplicated by another... 

Sight glasses and manual dipping are useful ancillary aids but are not in themselves sufficient safeguards. 

The adhesive film is uneven because it is thin on top of the parts (perhaps 20 to 50 microns) and thicker at the bottom, depending on the viscosity and rheology. Some examples of application of manual dipping are ... 

Cooling of rubber sheet would generally utilise a festoon cooler if plant size warranted it. Only the smallest compounding plants would use a manual dip and rack cooling system. 

As dipping LbL became an important technique toward making multifunctional nanostractured materials, efforts followed to improve the procedures for a better controlled deposition process with automated dipping robots. With such automated systems, it is possible to continue the deposition for a larger number of deposition cycles and reduce the variability and errors that may be caused by manual dipping. For example, the placement and orientation of the substrate inside the solution is important, and manual operation is prone to variability in substrate immersion, while in automated systems, the substrate is dipped into the solution without being released at the same orientation and speed at each deposition cycle. Several automated LbL deposition systems are commercially available. Also, scaled-up industrial processes can be adapted for LbL deposition for example, a roll-to-roll process has been adapted for commercial products. 

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