Editing Differential scanning calorimetry (section)

==Applications==
Differential scanning calorimetry can be used to measure a number of characteristic properties of a sample. Using this technique it is possible to observe [[melting point|fusion]] and [[crystal]]lization events as well as [[glass transition]] temperatures ''T<sub>g</sub>''. DSC can also be used to study [[oxidation]], as well as other chemical reactions.<ref name=Dean/><ref name=Pugnor/><ref>{{cite journal| vauthors = O'Neill MJ | title=The Analysis of a Temperature-Controlled Scanning Calorimeter|journal=Anal. Chem.|year=1964|volume=36|pages=1238–1245|doi=10.1021/ac60213a020|issue=7}}</ref>

[[Glass transition]]s may occur as the temperature of an [[amorphous]] solid is increased. These transitions appear as a step in the baseline of the recorded DSC signal. This is due to the sample undergoing a [[Kauzmann paradox|change in heat capacity]]; no formal phase change occurs.<ref name=Dean/><ref name=Skoog/>

As the temperature increases, an amorphous solid will become less [[viscosity|viscous]]. At some point the molecules may obtain enough freedom of motion to spontaneously arrange themselves into a crystalline form. This is known as the [[crystallization|crystallization temperature]] (''T<sub>c</sub>''). This transition from amorphous solid to crystalline solid is an exothermic process, and results in a peak in the DSC signal. As the temperature increases the sample eventually reaches its melting temperature (''T<sub>m</sub>''). The melting process results in an endothermic peak in the DSC curve. The ability to determine [[transition temperature]]s and [[enthalpy|enthalpies]] makes DSC a valuable tool in producing [[phase diagram]]s for various chemical systems.<ref name=Dean/>

Differential scanning calorimetry can also be used  to obtain valuable thermodynamics information about proteins. The thermodynamics analysis of proteins can reveal important information about the global structure of proteins, and protein/ligand interaction. For example, many mutations lower the stability of proteins, while ligand binding usually increases protein stability.<ref>{{cite journal | vauthors = Schön A, Brown RK, Hutchins BM, Freire E | title = Ligand binding analysis and screening by chemical denaturation shift | journal = Analytical Biochemistry | volume = 443 | issue = 1 | pages = 52–7 | date = December 2013 | pmid = 23994566 | pmc = 3809086 | doi = 10.1016/j.ab.2013.08.015 }}</ref> Using DSC, this stability can be measured by obtaining [[Gibbs free energy|Gibbs Free Energy]] values at any given temperature. This allows researchers to compare the free energy of unfolding between ligand-free protein and [[Ligand|protein-ligand]] complex, or wild type and mutant proteins. DSC can also be used in studying protein/lipid interactions, nucleotides, drug-lipid interactions.<ref name=":0">{{cite journal | vauthors = Chiu MH, Prenner EJ | title = Differential scanning calorimetry: An invaluable tool for a detailed thermodynamic characterization of macromolecules and their interactions | journal = Journal of Pharmacy & Bioallied Sciences | volume = 3 | issue = 1 | pages = 39–59 | date = January 2011 | pmid = 21430954 | pmc = 3053520 | doi = 10.4103/0975-7406.76463 | doi-access = free }}</ref> In studying protein denaturation using DSC, the thermal melt should be at least to some degree reversible, as the thermodynamics calculations rely on chemical equilibrium.<ref name=":0" />