In situ detector

Finally, the FT-IR system operates by coding the infrared source with an amplitude modulation which is unique to each infrared frequency. The detector is sensitive to the modulated radiation so that unmodulated stray radiation is eliminated from the experiment, permitting the use of the FT-IR as an in-situ detector in many experiments. For example, an FT-IR has been used to monitor the evolution of coal pyrolysis products within a drop tube furnace (24) and within an entrained flow reactor (25). The latter has been operated up to 1200 C. 

The primary data furnished by such detection then allows interpretation of kinetics and mechanisms and can serve as the basis for building specific quantitative, mechanistic models, as well as for controlling polymerization reactions. The ACOMP platform is one means of anbodying and employing any chosen set of such detectors, and these can also be complemented by widely used in situ detectors. 

MAS Ma, S.-L., Lu, Z.-W., Wu, Y.-T., and Zhang, Z.-B., Partitioning of dmg model compounds between poly(lactic acid)s and supercritical CO2 using quartz crystal microbalance as an in situ detector, J. Supercrit Fluids, 54, 129,2010. 

The usefulness of these findings in the context of spatial discrimination (i.e. delineating hotspot boundaries) might be questioned, because the characteristic of in situ measurements that reduces sampling uncertainty is the greater lateral extent of the specimen. Therefore a systematically spaced survey with an in situ detector will, by default, result in a lower spatial resolution than could theoretically be achieved by ex situ measurements (albeit at extremely high cost). The next part of this paper addresses the issue of spatial resolution, and it will be seen that the resolution of in situ measurements can be better understood, and can also be adjusted to meet survey objectives. 

For the purposes of survey design, understanding the size and shape of the volume of soil that is seen by an in situ detector would clearly be usefiil information. It might also assist in understanding the results of systematic in situ surveys. Note that this voliune has been termed here the sample-volume, and in this context sample refers to an individual specimen, not a set of results. 

In situ measurement of the concentration of radioactive tracers in the different phases requires that the phases are separated and arranged according to density difference over the measurement cross section in a horizontal pipe. In general, the measurements are performed with two spectral gamma radiation detectors placed on top and bottom of the pipe respectively. 

Soundness of safety shut-off valves in the closed position for both forward and reverse flow. Note that this should be done with the valve in situ and without dismantling it, by means of a bubble leak detector, etc. The valve should not be dismantled to check for swarf on the seat, etc. 

The period between such tests will depend on the maintenance schedule for the plant, which should also include the in-situ soundness testing of non-return valves and safety shut-off valves by bubble leak detectors, etc. 

Example 5.7 We have to design a servo-controller for a mixing system. A blue dye for making denim is injected into a stream of water. The injected dye is blended into the pipe flow with the aid of in situ static mixers. A photodetector downstream is used to monitor the dye concentration. The analog output of the detector is... 

FTIR spectra were collected with a Nicolet 740 spectrometer and a custom built in situ gas flow cell. The spectrometer was equipped with a MCT-B detector cooled by liquid nitrogen. Approximately 15 mg of the MgO catalyst sample was pressed into a self-supported disc and placed in a sample holder located at the center of the cell. The temperature in the cell was measured with a thermocouple placed close to the catalyst sample. Transmission spectra were collected in a single beam mode with a resolution of 2 cm 1. Prior to introduction... 

The recognition of the importance of MP in maintaining the health of the retina has led to the development of a number of methods for determining its concentration in situ. These methods, necessarily noninvasive, are routinely employed in dietary supplementation studies with lutein or zeaxanthin to monitor the uptake of the carotenoids into the retina. Every method exploits the optical properties of lutein and zeaxanthin, specifically their absorbance at visible wavelengths. The detection of a light signal, modified by the carotenoids, is accomplished either by the retinal photoreceptors themselves (psychophysical methods) or by a physical detector such as a photomultiplier,... 

Figure 2.81 (a) Schematic of the system for in situ X-ray reflectivity measurements. Syn = synchrotron source M = monochromator S = slit /0, /R = incident and reflected X-rays beams, respectively 9 = angle of incidence W = teflon windows WE = working electrode RE = reference electrode CF = counter electrode D = scintillation detector, (h) Cyclic voltammogram of Cu-on-Si electrode in borate buffer solution (pH 8.4), scan rate = lOmVs-1. From Melendres... 

The zeolite was pressed into thin pellet and activated in situ in IR cell in vacuum at 800 K for 1 h. The IR spectra were recorded with a Broker Equinox 55 spectrometer (equipped with an MCT detector) with the spectral resolution 2 cm 1. 

Oligonucleotide arrays [6] In-situ on the surface of the matrix 1 cm by 1 cm slide with approximately 40 000 genes Affymetrix s GeneChip can contain up to 400 000 different oligonucleotides and is the densest array Fluorescent tag labeling fluorophore detector is added after hybridization Passive Affymetrix... 

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