Chemical substance made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride) and refined sugar (sucrose). However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical. Chemical substances exist as solids, liquids, gases, or plasma, and may change between these phases of matter with changes in temperature or pressure. Chemical substances may be combined or converted to others by means of chemical reactions. Forms of energy, such as light and heat, are not matter, and are thus not "substances" in this
Chemical compound microarray Polymer microarrays have been developed to allow screening for new polymeric materials to direct different tissue lineages. Research has also been directed towards studying the surface chemistry of these arrays to determine which surface chemistries control cell adhesion, although concerns have been raised as to the influence of the substrate on measurements and the questionable statistical interpretation of results. The lack of control in the production of many of these polymer arrays suggests that any practical application of these technologies will be limited. This is particularly true for the in situ polymerisation of acrylate monomers in minute volumes. Chemical compound