The cycle is a combination of endothermic and exothermic neutronic reactions involving lithium and deuterium/tritium. Chemical reactions are either endothermic or exothermic, as expressed by their change in enthalpy. These have segregated compartments where exothermic or endothermic reactions provide the desired effect. This is the physical understanding of exothermic and endothermic reactions. The is a positive change in endothermic reactions, and negative in heat-releasing exothermic processes. In NVT, the energy of endothermic and exothermic processes is exchanged with a thermostat. SOEC module can operate in three different modes which are thermoneutral, exothermic and endothermic. Temperature extremes harm animals irrespective of whether they are endothermic or ectothermic. Carbon fixation is an endothermic redox reaction. Scientists disagree as to whether non-avian dinosaurs were endothermic, ectothermic, or some combination of both. This reaction is one of the exceptions to the endothermic nature of decomposition reactions. Net energy is absorbed by an endothermic reaction. Despite it being an endothermic compound, it is kinetically stable. Sintering under atmospheric pressure requires the use of a protective gas, quite often endothermic gas. Fire retardants may also cool the fuel through physical action or endothermic chemical reactions.