Probe measurement, schematic diagram

Sensitivity levels more typical of kinetic studies are of the order of lO molecules cm . A schematic diagram of an apparatus for kinetic LIF measurements is shown in figure C3.I.8. A limitation of this approach is that only relative concentrations are easily measured, in contrast to absorjDtion measurements, which yield absolute concentrations. Another important limitation is that not all molecules have measurable fluorescence, as radiationless transitions can be the dominant decay route for electronic excitation in polyatomic molecules. However, the latter situation can also be an advantage in complex molecules, such as proteins, where a lack of background fluorescence allow s the selective introduction of fluorescent chromophores as probes for kinetic studies. (Tryptophan is the only strongly fluorescent amino acid naturally present in proteins, for instance.)... 

Velocity transducers are electro-mechanical sensors designed to monitor casing, or relative, vibration. Unlike displacement probes, velocity transducers measure the rate of displacement rather than the distance of movement. Velocity is normally expressed in terms of inches per second (ips) peak, which is perhaps the best method of expressing the energy caused by machine vibration. Figure 43.22 is a schematic diagram of a velocity measurement device. 

This schematic diagram shows that the true composition of particles can be obtained only when the probe hole covers the particle entirely. When the probe hole covers both the particle and the matrix, the measured concentration is lower than the real one. Again, when an interface is not perpendicular to the cylinder of analysis, the apparent concentration change at the interface appears diffuse, even if the real concentration change is discrete. The standard deviation for concentration, a, is given by... 

Figure 7. Schematic diagram of a flowing-afterglow electron-ion experiment. The diameter of flow tubes is typically 5 to 10 cm and the length is 1 to 2 meters. The carrier gas (helium) enters through the discharge and flows with a velocity of 50 to 100 m/s towards the downstream end of the tube where it exits into a fast pump. Recombination occurs mainly in the region 10 to 20 cm downstream from the movable reagent inlet, at which the ions under study are produced by ion-molecule reactions. The Langmuir probe measures the variation of the electron density in that region. A differentially pumped mass spectrometer is used to determine which ion species are present in the plasma.

FIGURE 10.2 A schematic diagram of a combination glass pH electrode. A thin glass bulb with an inner Ag/AgCI electrode responds to pH changes in the test solution. A second Ag/AgCI in an outer jacket with a liquid junction serves the reference electrode for potentiometric measurement. An attached temperature probe is used to compensate for temperature effects. 

Figure 19.1. Schematic diagram of a general pump-probe-detect laser spectrometer suitable for picosecond electronic absorption, infrared (IR) absorption, Raman, optical calorimetry, and dichroism measurements. For picosecond fluorescence—a pump-detect method, no probe pulse needs to be generated.

Fig. 4.36 Schematic diagram of a solid electrolyte probe for the measurement of oxygen partial pressures (or chemical activities).

Figure 4. Charge-transfer processes at the liquid-liquid interface, (a) Probing ET at the liquid-liquid interface with the SECM. The kinetics of ET between two redox couples confined to different immiscible liquid phases can be measured with the SECM operating in the conventional feedback mode. Electroneutrality is maintained by transfer of the common ion (shown as an anion) across the interface (IT). Adapted with permission from Ref. [38]. Copyright 1995, American Chemical Society, (b) Schematic diagram of facilitated ion transfer reaction studied by SECM.

Fig. 1. Schematic diagram of a centrifugal impeller bioreactor (5 1). 1 Magnetic stirring device 2 gas in 3 head plate 4 agitator shaft 5 measurements of the liquid velocity profiles of the discharge flow were performed in the vertical direction across the width of the blades (the vertical dashed line) and at various radial distances from the impeller tip 6 sintered stainless sparger 7 centrifugal blade 8 draft tube 9 DO probe 10 centrifugal rotating pan...

Fig. 7. Schematic diagram of the canine femoral artery copper coil model of thrombolysis. A thrombogenic copper coil is advanced to either femoral artery via the left carotid artery. By virtue of the favorable anatomical angles of attachment, a hollow polyurethane catheter advanced down the left carotid artery nearly always enters the descending aorta, and with further advancement, into either femoral artery without fluoroscopic guidance. A flexible, Teflon-coated guidewire is then inserted through the hollow catheter and the latter is removed. A copper coil is then slipped over the guidewire and advanced to the femoral artery (see inset). Femoral artery flow velocity is measured directly and continuously with a Doppler flow probe placed just proximal to the thrombogenic coil and distal to a prominent sidebranch, which is left patent to dissipate any dead space between the coil and the next proximal sidebranch. Femoral artery blood flow declines progressively to total occlusion over the next 10-12 mm after coil insertion.

Figure 5.8. a Schematic diagram of a two-probe conductivity cell [9], (Reproduced by permission of ECS—The Electrochemical Society, from Xie Z, Song C, Andreaus B, Navessin T, Shi Z, Zhang J, Eloldcroft S. Discrepancies in the measurement of ionic conductivity of PEMs using two- and four-probe AC impedance spectroscopy) b Equivalent circuit of the two-probe method. 

Figure 2-18. Schematic diagram of a pressure probe, an apparatus used to measure P, L, (or LP, see Chapter 3, Section 3.5C), and e for individual plant cells. The intracellular hydrostatic pressure is transmitted to the pressure transducer via an oil-filled microcapillary introduced into the cell. Volume can be changed by adjusting the micrometer and observing the motion of the interface between the solution in the central vacuole and the oil (in the drawing the cell region is greatly enlarged relative to the rest of the apparatus).

Fig. 4 shows a schematic diagram of the NIR measurement system. The fiber optic probes of on-line Fourier transform NIR unit (FIRIOOOL, Yokogawa Electric CO.) were equipped with a high-pressure... 

FIG. 22 Schematic diagram of the SECM apparatus employed for probing interfacial reactions at the ITIES. An UME tip is used to measure the local concentration of a reactant or product in the near-interface region of an expanding droplet. (From Ref. 65.)... 

Figure 3. Description of systems used to generate and measure interior positive membrane potentials. (A) A schematic diagram for the ascorbate-TCNQ-K3Fe(CN)6 reaction. The interior positive membrane potential formation is catalyzed by the lipophilic electron carrier TCNQ, which mediates the flow of electrons from ascorbate inside the vesicle to K3Fe(CN)6 outside. (B) Membrane potential formation in reconstituted proteoliposomes was followed by the fluorescent probe oxonol V. (Reproduced with permission from reference 17. Copyright 1991 American Society for Biochemistry and Molecular Biology.)...

Figure 17 Schematic diagram of cone calorimeter for determining rate of heat release (ISO 5660 1) and smoke (draft ISO 5660 -2). 1. Load cell. 2. Test specimen. 3. Spark igniter. 4. Conical radiant heater. 5. Exhaust hood. 6. Gas sampling probe. 7. Laser, photocell. smoke delcimining system. 8. Pressure (velocity) measurement. 9. Exhaust fan.

Figure 25 Schematic diagram of room calorimeter test (ISO 7905). 1. Room. 2. Gas burner ignition source. 3. Room exit door. 4. Hood. 5. Fire gas mixing baffles. 6. Gas sampling, temperatures, and velocity probes, smoke measuring sensors. 7. Exhaust fan. Note Furniture calorimeter is similar but without room. Test. specimen is burned directly under hood (NT Fire 032).

A schematic diagram illustrating a typical thermomechanical analyzer is shown in Fig. 4.146. This instrument was produced by the Perkin-Elmer Co. Temperature is controlled through a heater and the coolant at the bottom. Atmosphere control is possible through the sample tube. The heavy black probe measures the position of the... 

Cake hei t has also been measured using six pressure probes positioned inside a filter cell. The hydraulic pressure was measured and remained constant until the filter cake surface reached the probe, when the hydraulic pressure started to fall. Thus the height of the filter cake surface was given from the known distance of the probe fi om the medium [Murase et al, 1989 b]. A schematic diagram of the ej erimental equiproent is given in Figure 2.27. 

Figure 1-3 shows a schematic diagram of a dynamic IR linear dichroism (DIRLD) experiment [20-25] which provided the foundation for the 2D IR analysis of polymers. In DIRLD spectroscopy, a small-amplitude oscillatory strain (ca. 0.1% of the sample dimension) with an acoustic-range frequency is applied to a thin polymer film. The submolecular-level response of individual chemical constituents induced by the applied dynamic strain is then monitored by using a polarized IR probe as a function of deformation frequency and other variables such as temperature. The macroscopic stress response of the system may also be measured simultaneously. In short, a DIRLD experiment may be regarded as a combination of two well-established characterization techniques already used extensively for polymers dynamic mechanical analysis (DMA) [26, 27] and infrared dichroism (IRD) spectroscopy [10, 11]. 

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