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In the Arrhenius model of reaction rates, activation energy is the minimum amount of energy that must be available to reactants for a chemical reaction to occur. [1] The activation energy ( Ea) of a reaction is measured in kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol). [2] Activation energy can be thought of as the magnitude ...
American Airlines Flight 11 was a domestic passenger flight that was hijacked by five al-Qaeda terrorists on the morning of September 11, 2001, as part of the September 11 attacks. The hijacked airliner was deliberately crashed into the North Tower of the World Trade Center complex in New York City, killing everyone aboard the flight and ...
Immunologic activation. In immunology, activation is the transition of leucocytes and other cell types involved in the immune system. On the other hand, deactivation is the transition in the reverse direction. This balance is tightly regulated, since a too small degree of activation causes susceptibility to infections, while, on the other hand ...
Carbon–hydrogen bond activation. In organic chemistry and organometallic chemistry, carbon–hydrogen bond activation ( C−H activation) is a type of organic reaction in which a carbon–hydrogen bond is cleaved and replaced with a C−X bond (X ≠ H is typically a main group element, like carbon, oxygen, or nitrogen ).
The activation-synthesis hypothesis, proposed by Harvard University psychiatrists John Allan Hobson and Robert McCarley, is a neurobiological theory of dreams first published in the American Journal of Psychiatry in December 1977. The differences in neuronal activity of the brainstem during waking and REM sleep were observed, and the hypothesis ...
The purpose of the camp is to provide temporary housing for asylum seekers as they await their registration processes. Kara Tepe was the overflow site for Moria Refugee Camp , the main registration center in Greece, and Europe's biggest refugee camp, [3] known as a 'hotspot' established by the Greek government through which new arrivals would ...
Activator (phosphor) In phosphors and scintillators, the activator is the element added as dopant to the crystal of the material to create desired type of nonhomogeneities. In luminescence, only a small fraction of atoms, called emission centers or luminescence centers, emit light. In inorganic phosphors, these inhomogeneities in the crystal ...
The plus sign ( +) and the minus sign ( −) are mathematical symbols used to denote positive and negative functions, respectively. In addition, + represents the operation of addition, which results in a sum, while − represents subtraction, resulting in a difference. [1] Their use has been extended to many other meanings, more or less analogous.