ConUol schematic, pneumatic

Separate sample blanking requires an additional analytical channel, and is therefore wasteflil of both reagents and hardware. An alternative approach that is used on several automated systems, eg, Du Pont ACA, BM-Hitachi 704, Technicon RA-1000, is that of bichromatic analysis (5) where absorbance measurements are taken at two, rather than one, wavelength. When the spectral curves for the interference material and the chromogen of the species measured differ sufficiently, this can be an effective technique for reducing blank contributions to assay error. Bichromatic analysis is effective for blanks of both the first and second type.  [c.393]

The structure of the selectivity filter has two essential features. First, the main-chain atoms create a stack of sequential oxygen rings along the passage, providing several closely spaced binding sites of the required dimensions for coordinating naked, dehydrated K+ ions. The K+ thus have only a small distance to diffuse from one site to the next within the selectivity filter. Second, the side chains of the residues that provide these binding sites point away from the channel and pack against the side chains from the pore helices. This packing firmly fixes the positions of the main-chain atoms, including the oxygen atoms that bind K. Since the side chains involved in these packing interactions are invariant in all known K+ channels it is reasonable to assume that the carbonyl oxygen atoms are fixed in positions with the correct dimensions to provide strong binding sites for K. The resolution of the structure determination is, however, too low to establish details of these binding sites.  [c.234]

Deliver from a pipette 10 c.c. of the oil into a glass dish (preferably a round-bottom one) of 50 c.c. capacity, which is imbedded in finely cracked ice. Add 10 c.c. of concentrated arsenic acid (containing about 85 per cent, arsenic acid), and stir until precipitation is complete. When the mixture ceases to congeal further, allow to stand ten minutes in the ice. At this point if the mixture forms a hard mass, indicating an oil rich in cineol, 5 c.c. of purified petroleum ether should be added, and the mass mixed well. Transfer immediately to a hardened filter paper by means of a pliable horn spatula, spread evenly over the surface of the paper, and lay a second hardened filter paper over the top. Outside of the hardened filters place several thicknesses of absorbent or filter paper, and transfer the whole to an ordinary letter-press, bringing to bear all the pressure  [c.281]

Consider die following intuitive scheme, in which the timing between a pair of pulses is used to control the identity of products [ ]. The scheme is based on the close correspondence between the centre of a wavepacket in time and that of a classical trajectory (Elirenfest s theorem). The first pulse produces an excited electronic state wavepacket. The time delay between the pulses controls the time that the wavepacket evolves on the excited electronic state. The second pulse stimulates emission. By the Franck-Condon principle, the second step prepares a wavepacket on the ground electronic state with the same position and momentum, instantaneously, as the excited-state wavepacket. By controlling the position and momentum of the wavepacket produced on the ground state through the second step, one can gain some measure of control over product fonnation on the ground state. This pump-dump scheme is illustrated classically in figure Al.6.27. The trajectory originates at the ground-state surface minimum (the equilibrium geometry). At t = 0 it is promoted to the excited-state potential surface (a two-dimensional hamionic oscillator in this model) where it originates at the Condon point, that is, vertically above the ground-state minimum. Since this position is displaced from equilibrium on the excited state, the trajectory begins to evolve, executing a two-dimensional Lissajous motion. After some time delay, the trajectory is brought down vertically to the ground state (keeping both the instantaneous position and momentum it had on the excited state) and allowed to continue to evolve on the ground-state, figure Al.6.27 shows that for one choice of time delay it will exit mto chaimel 1, for a second choice of time delay it will exit into channel 2. Note how the position and momentum of the trajectory on the ground state, innnediately after it comes down from the excited state, are both consistent with the values it had when it left the excited state, and at the same time are ideally suited for exiting out their respective chaimels.  [c.270]

See pages that mention the term ConUol schematic, pneumatic : [c.781]    [c.108]   
Turboexpanders and Process Applications (0) -- [ c.475 ]