Suppression of the spontaneous

The optical purities were determined solely from the optical rotations of the (/ -cyanohydrins thus obtained. Only for (/ )-a-hydroxybcnzeneacetonitrile, available from benzaldehyde, was an optical purity determined by comparison with the natural product. Variation of the reaction conditions (pH, temperature, concentration) in water/ethanol led to no appreciable improvementsl4. The use of organic solvents that are not miscible with water, but in which the enzyme-catalyzed reaction can still take place, resulted in suppression of the spontaneous addition to a significant extent, whereas the enzyme-catalyzed formation of cyanohydrins was only slightly slower (Figure l)13. 

The suppression of the spontaneous emission of a hydrogen atom in the 2/ o) = a) state, which can only decay to a single (the ground IS q)) state, is briefly presented here. It can be achieved by coupling the 2Po) state with the 3.S) = b) state using a resonant CW laser field. 

In Reference [38], it is further shown that suppression of the spontaneous emission can be equally well achieved in a molecular system. The difficulty with molecular systems lies in the fact that there is usually a multitude of final states to which the system can emit. In this example, suppressing the emission from a particular vibrational state a) belonging to the 1 S (A) electronic manifold of the Sodium dimer is considered, when aided by a particular vibrational state b) belonging to the 2 electronic manifold. The relevant potentials are displayed in Figure 9.12. 

Figure 9.13 Suppression of the spontaneous emission of the sodium dimer. The optimization time T (marked by a triangle) is 0.2/r(= 10 ns), and the total time range displayed is up to 3/F(= 150 ns). AE is the Autler-Townes splitting induced by die CW laser and F is the natural linewidth. Reprinted figure by permission from Ref. [38]. Copyright 2003 by the American Physical Society.

Behavioral effects Several behavioral effects of valerian have been noted in animals. These include suppression of the orienting response in an open-field paradigm, decreasing spontaneous and caffeine-induced motor... 

Neurophysiological studies show that the BZs potentiate the neuronal inhibition that is mediated by GABA. In doses used clinically, this results in a generalized suppression of both spontaneous and evoked electrical activity of the large neurons throughout all regions of the brain and spinal cord (Ballenger, 1995). 

Figure 9.6. Schematic of repulsion or attraction forces (which vary with distance from the particle surface) between particles in suspension. Curves 1 and 6 are examples of repulsion and attraction curves, respectively, which vary with the colloid and the kinds and amounts of electrolytes. A summation of curves 1 and 6 for different conditions produces curves 2-5. In curve 2, the energy of repulsion predominates and a stable suspension is formed. Increasing electrolyte produces curves 3, 4, or 5 owing to suppression of the electric double layer. Curve 3 shows there is still an energy barrier to be overcome prior to flocculation. When the colloids surmount this energy barrier and approach closer than point C, flocculation occurs because the forces of attraction predominate. Curve 5 suggests spontaneous flocculation without redispersion unless there is a shift toward curve 2 by reexpanding the double layer through changing kinds and/or amounts of electrolytes (adapted from Kruyt, 1952).

Although rare, acute hemolytic anemia can occur. This may reflect an immune reaction or may be due to glucose-6-phosphate dehydrogenase deficiency. Agranulocytosis occurs in -0.1% of patients who receive sulfadiazine and also can occur with other sulfonamides. Although neutropenia may persist for weeks or months after sulfonamide is withdrawn, most patients recover spontaneously with supportive care. Pancytopenia with complete suppression of bone-marrow activity is extremely rare. It probably results from a direct myelotoxic effect and may be fatal. Reversible suppression of the bone marrow is quite common in patients with limited bone marrow reserve (e.g., patients with AIDS or those receiving myelosuppressive chemotherapy). 

Ventilation means forced gas exchange with several risks that are caused by the replacement of spontaneous breathing with suppression of the natural respiratory drive, the application of... 

Other phenomena that influence the modulation dy-nanucs of semiconductor lasers include the spontaneous emission, gain saturation, and the external electrical connections to the device. These effects normally manifest themselves as a suppression of the relaxation oscillations, which reduces the peak of the modulation response and also reduces the modulation bandwidth. 

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