In the latter sense, it may refer to a surface on which other chemical reactions are performed or play a supporting role in a variety of spectroscopic and microscopic techniques, as discussed in the first few subsections below.
[3] Typically silver, gold, or silicon wafers are used due to their ease of manufacturing and lack of interference in the microscopy data.
Samples are deposited onto the substrate in fine layers where it can act as a solid support of reliable thickness and malleability.
[2][4] Smoothness of the substrate is especially important for these types of microscopy because they are sensitive to very small changes in sample height.
This type of diffraction, which involves directing high-powered X-rays at powder samples to deduce crystal structures, is often performed with an amorphous substrate such that it does not interfere with the resulting data collection.
[7] In atomic layer deposition, the substrate acts as an initial surface on which reagents can combine to precisely build up chemical structures.
A substrate is critical in this technique because the first layer needs a place to bind to such that it is not lost when exposed to the second or third set of reagents.
[citation needed] For example, curd formation (rennet coagulation) is a reaction that occurs upon adding the enzyme rennin to milk.
[11] In another example, the N-acyl taurines (NATs) are observed to increase dramatically in FAAH-disrupted animals, but are actually poor in vitro FAAH substrates.
[13] Moderate sensitive substrates are drugs that demonstrate an increase in AUC of ≥2 to <5-fold with strong index inhibitors of a given metabolic pathway in clinical DDI studies.