Pulse typical configuration

An orifice flow configuration is more suitable for applications requiring intense cavitational conditions, whereas for milder processes (requiring collapse pressure pulses typically between 15 and 20 bar) and for transformations based on physical effects, a venturi configuration is more suitable and energy efficient. 

Figure 15.7. Typical configurations used in biological MS. In MALDI-TOF, the ions produced by a short laser pulse travel across a flight tube, arriving at different times at the detector. In ESI-triple quadrupole, the first quadrupole (Ql) is used to separate the sprayed ions, in the second (Q2, also called the fragmentation cell) argon atoms collide with the ions the resulting ions (daughter ions) are analyzed in Q3, and subsequently detected.

After this prerun, the voltage is programmed to periodically pulse a plug of analyte into the interface. This fraction is then drawn into the second capillary for further separation. In our current configuration, the separation window in the CSE dimension is roughly 200 s in duration, and roughly 200 pulses of 1 s duration are required for the contents of the CSE capillary to be transferred to the second dimension. A constant potential is applied across the second dimension capillary, typically 10,000-20,000 V. Under this constant voltage, any analyte present within the interface is driven into the second dimension capillary for separation. Detection is by laser-induced fluorescence in a postcolumn sheath-flow cuvette. 

A typical experimental configuration consists of a measurement cell which contains the sample, a pulse generator, an ultrasonic transducer and an oscilloscope (Figure 4). The pulse generator produces an electrical pulse of an appropriate frequency and amplitude. This pulse is converted into an ultrasonic pulse by the transducer. It then propagates through the sample until it reaches the far wall of the cell where it is reflected back to the transducer. The... 

Fed-batch cultivation (A) operational configuration and typical volume, cell, and substrate profiles, for a pulse feeding strategy (B) concentration of cells, product, and two substrates in a fed-batch bioreactor culture of a myeloid transfectoma producing a humanized monoclonal antibody (Center of Molecular Immunology-CIM, Cuba). 

Experimental Setups. The experimental configurations used for CARS measurements have common features in most laboratories now. Figure 2 shows one such arrangement which is typical. A pulsed laser, in most cases a Q-switched Nd YAG, is used to generate the (o. frequency at 532 nm. In a few cases experimenters use ruby or other solid state pulsed lasers. Typically the 532 nm beam is split and the second beam is used to pump a dye laser -dye laser amplifier leg. This produces the ou probe frequency. 

If the molecular continuum is unstructured, we can invoke the SVCA and replace the energy-dependent bound-continuum dipole matrix elements by their value at the -pulse center, given (in the A configuration of Fig. 10. lc) as EL = E2 — fioj2. This is the case, for example, for Na2 at threshold energies, where the bound-continuum ( dipole matrix elements vary with energy by less than 1% over a typical nanosecond-pulse bandwidth. Within the SVCA, Eq. (11.61) becomes... 

Fig. 2. A typical pulsed, tunable dye laser, of the Hansch design, in an oscillator— amplifier configuration. Suitable pump lasers are Nj, excimer and Nd YAG-harmonics. The broken line represents a pressure chamber which is required to scan the wavelength if an air spaced Fabry—Perot etalon is used. With solid etalons, tuning is achieved by tilting the etalon and the pressure chamber is not required.

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