Pulse-mode units

Amperometric 1 x10-9g 2 x 104 Responds to -OH functionalities Used for alphatic and aromatic -OH compounds, amines, and indoles pulsed potential units are most sensitive, can be used with gradient elution and organic mobile phases senses compounds in oxidatitive or reductive modes mobile phases must be highly pure and purged of 02... 

Sonophoresis has employed three distinct categories of US high-frequency or diagnostic US (2-10 MHz), mid-frequency or therapeutic US (0.7-3 MHz), and low-frequency US (5-100 kHz). It appears, from a general overview of the literature, that the efficiency of US-mediated drug delivery depends on several factors, including US frequency, intensity (i.e., power per unit area), continuous versus pulsed mode, duty cycle, duration, coupling medium, and so on. The fact that very few studies have used common values for some or any of these parameters almost certainly accounts for the different and sometimes contradictory results in the public domain. 

The unit is operated in a pulsed mode which increases the momentary concentration of NO2, thereby improving its sensitivity. Figure 1 shows the typical response to various concentration of NO2 in a continuous mode. 

A/ is the intensity decrease on traversing unit distance in a sample with ground-state population density of A typical value of 5 is 10" ° cm" s photon" molecule" and at 1 torr pressure Ng is about 10 molecules cm . In this case a relative attenuation A/// of 10" is obtained at 7=10 photons cm" s", i.e., about 10 watt cm" s" for visible radiation. Powers of these orders of magnitude, at narrow frequency bandwidths, are practical only with laser sources. For TPE applications, lasers are often (not always) operated in a pulsed mode, allowing easy... 

Figure 3. The increase in the incident UV light intensity enhances the cross-linking rate, as indicated by the larger slopes of the elastic modulus (G ) plotted as a function of UV exposure time. The use of either the pulse or continuous modes of irradiation do not affect the rheological properties for the NOA 61 sample. Here, the frequency of oscillation is 10 rad/s and the intensities have units of mW cm 2.

Fig. 5.19. Evolutionary track in the HR diagram of an AGB model of total mass 0.6 Mq, initial composition (Y, Z) = (0.25, 0.001 Z /20). Heavy dots marked 2 to 11 indicate the start of a series of thermal pulses (see Fig. 5.20), which lead to excursions along the steep diagonal lines. Numbers along the horizontal and descending track indicate times in years relative to the moment when an ionized planetary nebula appears and (in parentheses) the mass of the envelope in units of Mq. R = 0.0285 indicates a line of constant radius (R in solar units) corresponding to the white-dwarf sequence. Shaded areas represent earlier evolutionary stages for stars with initial masses 3,5 and 7 Mq and the steep broken line marks the high-temperature boundary of the instability strip in which stars pulsate in their fundamental mode. The y-axis gives log L/Lq. Adapted from Iben and Renzini (1983).

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