CRDS

The fact that the transmitted intensity decreases exponentially with time forms the basis of cavity ring-down spectroscopy (CRDS). 

Both the a-X and b-X transitions have long been known from absorption by the oxygen in the earth s atmosphere, the source of radiation being the sun and the very long path length of oxygen overcoming their extreme weakness. For laboratory observation of these transitions, and particularly for accurate determination of absolute absorption intensity, CRDS has proved to be an ideal technique. 

Observation, in the laboratory, of the a-X system of O2 represents a greater challenge because it is much weaker than the b-X system. It has been observed using CRDS, a 1.5 m cavity and O2 at atmospheric pressure. Because the transition is in the near infrared, mirror reflectivity is very high thereby increasing the sensitivity. 

In Section 6.1.3 it was noted that vibrational overtone transitions, whether observed by infrared or Raman spectroscopy, are very weak. They become even weaker as the vibrational quantum number increases. The high sensitivity of CRDS makes it an ideal technique for attempting to observe such transitions. 

Seismic design basis for the reactor vessel (including attachments, pressure boundary, and CRD and internals). 

The coalescence-redispersion (CRD) model was originally proposed by Curl (1963). It is based on imagining a chemical reactor as a number population of droplets that behave as individual batch reactors. These droplets coalesce (mix) in pairs at random, homogenize their concentration and redisperse. The mixing parameter in this model is the average number of collisions that a droplet undergoes. 

Of the very sensitive laser-based absorption techniques, CRDS has developed into a widely applied technique in combustion diagnostics within only a few years... 

Cavity-enhanced absorption techniques are also applied in flames in the near infrared [22-25]. The multiple absorption paths provided with these techniques are the reason for their superb sensitivity in the ppb range. Absolute concentrations can be obtained, provided the absorption coefficient for the respective transition is known. CRDS can be used in conjunction with other laser-based combustion diagnostics for... 

For the analysis of the chemical structure of flames, laser methods will typically provide temperature measurement and concentration profiles of some readily detectable radicals. The following two examples compare selected LIF and CRDS results. Figure 2.1 presents the temperature profile in a fuel-rich (C/O = 0.6) propene-oxygen-argon flame at 50 mbar [42]. For the LIF measurements, 1% NO was added. OH-LIF thermometry would also be possible, but regarding the rather low OH concentrations in fuel-rich flames, especially at low temperatures, this approach does not capture the temperature rise in the flame front [43]. The sensitivity of the CRDS technique, however, is superior, and the OH mole fraction is sufficient to follow the entire temperature profile. Both measurements are in excellent agreement. For all flames studied here, the temperature profile has been measured by LIF and/or CRDS. 

Temperature profile measurement in a flat, premixed fuel-rich pro-pene low-pressure flame by LIF, using seeded NO, and CRDS, using naturally present OH radicals. (Adapted from Figure 3 in Kohse-Hoinghaus, K. et al., Z. Phys. Chem., 219,583,2005.)... 

Comparison of the C2 radical mole fraction profile measured by LIF and CRDS in a flat, premixed fuel-rich propene flame at 50mbar. 

C-type lectins Characterized by a Ca +-dependent carbohydrate recognition domain (CRD) includes the mammalian asialoglycoprotein receptor, the selectins, and the mannosebinding protein... 

Energy Lab., CRD, Samsung SDI, Suwon 443-731, Republic of Korea 1. INTRODUCTION... 

Rapid-Scan Corrosion Behavior Diagram (CRD) Basically, all the same equipment used in the conductance of an ASTM G5 slow-scan polarization study is used for rapid-scan CBDs (that is, a standard test cell, potentiostat, voltmeters, log converters, X-Y recorders, and electronic potential scanning devices). The differences are in technique the slow scan is run at a potential sweep rate of about 0.6 V/h the rapid-scan CBDs at about 50 V/h. 

The most common CRDs include jet lag, shift-work sleep disruption, delayed sleep-phase disorder, and advanced sleep-phase disorder. Jet lag occurs when a person travels across time zones, and the external environmental time is mismatched with the internal circadian clock. Delayed and advanced sleep-phase disorders occur when bed and wake times are delayed or advanced (by 3 or more hours) compared with socially prescribed bed and wake times. 

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