Dual-channel

Two examples of dual-channel manifolds for use In flow Injection analysis where R1 and R2 are reagent reservoirs P Is the pump S Is the sample I Is the Injector B Is a bypass loop W Is waste C Is the mixing and reaction coll and D Is the detector. 

Dual Channel Plot from a Diode Array Detector Confirming Peak... 

Reactor type Dual-channel micro reactor Base plate material of interfacing chip housing Silicon stainless steel... 

Figure 5.6 Flow pattern map for a gas/liquid flow regime in micro channels. Annular flow wavy annular flow (WA) wavy annular-dry flow (WAD) slug flow bubbly flow annular-dry flow (AD). Transition lines for nitrogen/acetonitrile flows in a triangular channel (224 pm) (solid line). Transition lines for air/water flows in triangular channels (1.097 mm) (dashed lines). Region 2 presents flow conditions in the dual-channel reactor ( ), with the acetonitrile/nitrogen system between the limits of channeling (I) and partially dried walls (III). Flow conditions in rectangular channels for a 32-channel reactor (150 pm) (T) and singlechannel reactor (500 pm) (A) [13].

GL 1] [R 4][P 2] For the dual-channel micro reactor, the highest yield of 14% was found using acetonitrile (58% conversion 24% selectivity) [13]. Slightly lower yields were obtained for methanol. The selectivities were as high as for acetonitrile, the conversion being lower. Still lower yields (7%) were achieved in octafluorotoluene for the same reason as for methanol, selectivity decreasing considerably. 

GL 1] [R 4] [P 2] Variation of solvent affects also the substitution pattern to a certain extent [13], A ratio of ortho-, meta- and para-isomers for mono-fluorinated toluene amounting on average to 3.5 1 2 was found in the dual-channel micro reactor at room temperature, using acetonitrile as solvent [13]. Using methanol as solvent, the ratio was on average 5.5 1 2.4. Hence more products referring to an electrophilic substitution were formed [13]. 

GL 1] [R 4] [P 2] A temperature rise of 0.4 K was estimated for a typical experiment in a dual-channel micro reactor based on assuming reaction rates and heat conductivity of the medium [13]. However, there are experimental indications that the real value is higher. 

Differential ionic chromatography. In a potentiometric method for recording ion-exchange elution curves, a dual-channel membrane cell is used as a differential detector186 for following the eluate composition in comparison with the eluent. In the chromatography of alkali metal ions over a... 

Figure 12-13 Input Capacitor Current Possibilities for Dual Channel Out-of-phase Buck Switchers...

Choi K, Hamilton AD (2001) A dual channel fluorescence chemosensor for anions involving intermolecular excited state proton transfer. Angew Chem Int Ed 40 3912-3913... 

In addition to the emission due to the test element, radiation is also emitted by the flame itself. This background emission, together with turbulence in the flame, results in fluctuations of the signal and prevents the use of very sensitive detectors. The problem may be appreciably reduced by the introduction into the sample of a constant amount of a reference element and the use of a dual-channel flame photometer, which is capable of recording both the test and reference readings simultaneously. The ratio of the intensity of emission of the test element to that of the reference element should be unaffected by flame fluctuations and a calibration line using this ratio for different concentrations of the test element is the basis of the quantitative method. Lithium salts are frequently used as the reference element in the analysis of biological samples. 

Dual-channel instruments are very similar to their single-channel counterparts and differ only in the fact that they analyse each sample for two constituents simultaneously. The sample stream is divided into two fractions, each one flowing independently through its own system of tubing with the appropriate reagents and detectors. 

FIGURE 2 HPLC chromatogram of Drug A and Drug B at dual channel (dual wavelength Xj only). 

Figure 10. SPR dual-channel sensors based on wavelength division multiplexing (WDM) of sensing channels. WDM of sensing channels by means of altered angles of incidence (upper). WDM of sensing channels by means of a high refractive index overlayer (lower) .

J. Homola, H. B. Lu, and S. S. Yee, "Dual-Channel Surface Plasmon Resonance Sensor with Spectral Discrimination of Sensing Channels Using a Dielectric Overlayer,"... 

Figure 12 Schematic of dual-channel Fido for the reduction of false positives. Illustration courtesy of ICxTechnologies.

Figure 13 Differential Responses of TNT and DNT, and a volatile interferent, in a dual- channel Fido sensor based on AFP technology. Figure courtesy of ICxTechnologies.

Figure 6.6 Example components available for simple photometers (A) a dual channel detector, (B) a quad, four-channel detector, (C) an example filter wheel with 8-filter channels, and (D) example MEMS-based IR...

From the practical point of view, dual-channel phase detectors operated in quadrature appear to be the best hardware-detection choice. Unlike other techniques, phase detection is sensitive to RF frequency offset from resonance and to the RF phase which, on the one hand, makes the signals more complex to use (as well as and more sensitive to instrument instabilities) but, on the other hand, leads to a number of important advantages, such as ... 

As usual, we shall from now on consider the output of the dual-channel phase detector as a unique complex signal, with the outputs of the two channels identified by its Cartesian components. 

Harmonic analysis was carried out on the specimens 7 days after the impedance measurements in order to allow the specimens to settle down again. An Ono Sokki CF 910 dual channel FFT analyser was used in conjunction with a potentiostat (Thompson Mlnistat 251) to hold the specimen at its rest potential and to provide the low frequency sine wave perturbation. The second channel was used to measure the harmonic content of the resulting current. The Ono Sokki produces a dlgltially generated high purity sine wave at a chosen frequency, in this instance, 0.5 Hz. The total harmonic content of the input sine wave was less than 0.45% measured over 10 harmonics. Only the first 3 harmonics are used to calculate the corrosion current. 

Figure 2.8 shows the general arrangement of the instrument with 100 optical cuvettes radially dispersed around the vertical axis of the reaction rotor. The optical components of the dual-channel monochromator are rigidly mounted within a machined aluminium housing (which is not shown in the diagram), and the housing itself is sohdly fixed to the top of the rotor. 

Fig. 32 Diagram of image formation within a photosensitive polymeric film containing PAG, and acid-sensitive fluorophore, allowing two-photon-induced, dual-channel fluorescence imaging...

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