Time scales burning

All these energies are renewable, but on a human time scale we find it inconvenient to wait millions of years for fossil fuels to be regenerated. Hydro, wind, solar, and food are truly renewable on our human time scale. Burning wood (and other biomass) is renewable energy on our time scale - but only if we don t consume it too fast and run out. 

Pump-probe absorption experiments on the femtosecond time scale generally fall into two effective types, depending on the duration and spectral width of the pump pulse. If tlie pump spectrum is significantly narrower in width than the electronic absorption line shape, transient hole-burning spectroscopy [101. 102. 103. 104. 105. 106. 107. 108. 109. 110. 111. 112 and 113] can be perfomied. The second type of experiment, dynamic absorption spectroscopy [57, 114. 115. 116. 117. 118. 119. 120. 121 and 122], can be perfomied if the pump and probe pulses are short compared to tlie period of the vibrational modes that are coupled to the electronic transition. 

Flammability. Most nylons ate classified V-2 by the Underwriters Laboratory UL-94 test, which means that these nylons are self-extinguishing within a certain time-scale under the conditions of the test. They achieve this performance by means of giving off burning drips. 

If Da = 1 is defined as the transition between diffusionally controlled and kinetically controlled regimes, an inverse relationship is observed between the particle diameter and the system pressure and temperature for a fixed Da. Thus, for a system to be kinetically controlled, combustion temperatures need to be low (or the particle size has to be very small, so that the diffusive time scales are short relative to the kinetic time scale). Often for small particle diameters, the particle loses so much heat, so rapidly, that extinction occurs. Thus, the particle temperature is nearly the same as the gas temperature and to maintain a steady-state burning rate in the kinetically controlled regime, the ambient temperatures need to be high enough to sustain reaction. The above equation also shows that large particles at high pressure likely experience diffusion-controlled combustion, and small particles at low pressures often lead to kinetically controlled combustion. 

Figure 9.4 shows one interpretation of the atmospheric CO2 history of Earth over a time period of 100 million years. The geologic record of atmospheric CO2 will be addressed in detail in Chapter 10 of interest here is the possibility that humankind activities of fossil fuel burning and land use practices could lead to future atmospheric CO2 levels rivaling those of the past. Furthermore the future time scale of atmospheric CO2 change may be shorter than any period of CO2 change the Earth has experienced in 100 million years. 

Additional evidence for structural flexibility of small peptides on very fast time scales can be obtained from dynamical hole-burning experiments. An example is shown in Fig. 23, (30) which reflects a cut through the 2D... 

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