Activation energy source

Four different activation energy sources have been used for the direct synthesis of[NF4]-" salts ... 

In this design concept, the primarily "active", highly redundant safety equipment of today s operating plants are replaced by "passive" safety equipment. These function according to basic laws of physics such as gravity, natural convection and evaporation. For this reason they have no need of "active" energy sources such as a permanent power supply. 

Method I. NF3 is reacted directly with Fg in the presence of a fluoride ion acceptor and under the action of a suitable activation energy source... 

Figure 19.6 The diffusion coefficient D of carbon in iron as a function of temperature logD versus 1/7 is linear, indicating a constant activation energy. Source RJ Borg and CJ Dienes, The Physical Chemistry of Solids, Academic Press, Boston, 1992.

An estimate of the enthalpy change which conesponds to the activation energy of the collision theory analysis of 167kJmoP may be made by assuming that the formation of tire dimer from two molecules of the monomer is energetically equivalent to tire dipole-dipole and dispersion interactions of two HI molecules. These exothermic sources of interaction are counterbalanced... 

The gradients of H, Na, and other cations and anions established by ATPases and other energy sources can be used for secondary active transport of various substrates. The best-understood systems use Na or gradients to transport amino acids and sugars in certain cells. Many of these systems operate as symports, with the ion and the transported amino acid or sugar moving in the same direction (that is, into the cell). In antiport processes, the ion and the other transported species move in opposite directions. (For example, the anion transporter of erythrocytes is an antiport.) Proton symport proteins are used by E. coU and other bacteria to accumulate lactose, arabinose, ribose, and a variety of amino acids. E. coli also possesses Na -symport systems for melibiose as well as for glutamate and other amino acids. 

After some experience with MNDO, it became clear that there were certain systematic en ors. For example the repulsion between two atoms which are 2-3 A apart is too high. This has as a consequence that activation energies in general are too large. The source was traced to too repulsive an interaction in the core-core potential. To remedy this, the core-core function was modified by adding Gaussian functions, and the whole model was reparameterized. The result was called Austin Model 1 (AMl) in honour of Dewar s move to the University of Austin. The core-core repulsion of AMI has the form ... 

The word laser is an acronym for light amplification by the stimulated emission of radiation. Lasers of all kinds consist of several basic components an active medium, an outside energy source, and an optical cavity with carefully designed mirrors on both ends. One of the mirrors is 100 percent reflective... 

Activation period. This is in two parts, the dry run and the live run, the change between the two being when fuel is made available to the combustion space. The activation period commences with all energy sources isolated from the plant. These are gradually made available as the dry run progresses. Fuel must be... 

Chemically active plastics such as the polyelectrolytes have been used to make artificial muscle materials. This is an unusual type of mechanical power device that creates motion by the lengthening and shortening of fibers made from a chemically active plastic by changing the composition of the surrounding liquid medium, either directly or by the use of electrolytic chemical action. Obviously this form of mechanical power generation is no competitor to thermal energy sources, but it is potentially valuable in detector equipment that would be sensitive to the changing... 

Methyl methacrylate can also be polymerized by radiation using either a cobalt-60 source or accelerated electrons at dose rates up to 3 megarads/sec. The activation energy for the electron beam polymerization is about 7.0kcal/ mole (Ref 12). Radical polymerization can also occur using diisocyanates or hydroperoxides as the initiating species (Ref 15)... 

Kinetic studies have been carried out using the 1 1-complex iodobenzene dichloride as a source of molecular chlorine. In acetic acid solutions, the dissociation of this complex is slower than the rate of halogenation of reactive aromatics such as mesitylene or pentamethylbenzene, consequently the rate of chlorination of these is independent of the aromatic concentration. Thus at 25.2 °C first-order chlorination rate coefficients were obtained, being approximately 0.2 x 10-3 whilst the first-order dissociation rate coefficient was 0.16 xlO-3 from measurements at 25.2 and 45.6 °C the corresponding activation energies... 

---