Determinations, in situ

Those Warren-Cowley parameters have been determined in situ above the order-disorder transition temperature by diffuse neutron scattering. From these experimentally determined static correlations, the first nine effective pair interactions have been deduced using inverse Monte Carlo simulations. 

Madsen EL (1991) Determining in situ biodegradation. Facts and challenges. Environ Sci Technol 25 1663-1673. 

A more complex but faster and more sensitive approach is polarization modulation (PM) IRLD. For such experiments, a photoelastic modulator is used to modulate the polarization state of the incident radiation at about 100 kHz. The detected signal is the sum of the low-frequency intensity modulation with a high-frequency modulation that depends on the orientation of the sample. After appropriate signal filtering, demodulation, and calibration [41], a dichroic difference spectrum can be directly obtained in a single scan. This improves the time resolution to 400 ms, prevents artifacts due to relaxation between measurements, and improves sensitivity for weakly oriented samples. However, structural information can be lost since individual polarized spectra are not recorded. Pezolet and coworkers have used this approach to study the deformation and relaxation in various homopolymers, copolymers, and polymer blends [15,42,43]. For instance, Figure 7 shows the relaxation curves determined in situ for miscible blends of PS and PVME [42]. The (P2) values were determined... 

Concentrations of OH and HO2 were determined, in situ, using Laser Induced Fluorescence (LIF) at low pressure, (FAGE technique). HO2 cannot be detected directly by LIF, and was converted to OH by titration with NO directly below the sampling nozzle. The detection limit for the FAGE instrument during SOAPEX-2, determined by calibration in the field, was 1.4 xlO5 molecule cm-3 for OH and 5.4x 105 molecule cm-3 for HO2. A description of the instrument, as set up in previous field campaigns and dur-... 

In these studies, chemical conversion was determined in situ by measuring the lH resonance associated with OH groups present. In practice two such resonances exist associated with chemical species inside and outside the catalyst particles, respectively. The difference in chemical shift between these intra- and inter-particle species arises because of the different electronic environment of the molecules inside the catalyst particles compared to their environment in the bulk fluid in the inter-particle space. In this work, chemical conversion was determined from the MR signal acquired from species in the inter-particle space of the bed because the signal from inside the catalyst particles is also going to be influenced, to an unknown extent, by relaxation time contrast. In addition to possible relaxation contrast effects, there will also be modifications to the chemical shifts of individual species resulting from adsorption onto the catalyst this may cause peak broadening and reduces the accuracy with which we can determine the chemical shift of the species of interest. As follows from eqn (11) which describes the esterification reaction of methanol and acetic acid to form methyl acetate and water ... 

Therefore, the best approach to investigate photoresist swelling is to determine, in-situ, the SCP in a polymer undergoing dissolution. Although Crank (12) proposed a descriptive SCP in 1953, firm experimental data started to appear only recently. Thomas and Kindle s microdensitometry (13-161 and Kramer s Rutherford back-scattering (17-181 produced SCP of several solvent-polymer combinations. However, these efforts were limited by the spatial resolution of their techniques (ca. 30 nm). In addition, these techniques have been applied to systems where the SPR s are on the order of 1 /xm/hour or less. 

Several papers have been published in which, instead of concentrating on specific reactions, the technology was highlighted. One, by Marose et al.,7 discusses the various optics, fiber optics, and the probe designs that allow in situ monitoring. They describe the various optical density probes used for biomass determination in situ microscopy, optical biosensors, and specific sensors such as NIR and fluorescence. 

The concentration of a species is usually determined in situ using some physical property which is linearly dependent on its concentration. By far the most utilized is the uv/vis absorbance (see (1.80) and (3.21)). 

Lassen and Malmsten have performed ellipsometrically determined in situ protein adsorption measurements on the above plasma polymer surfaces with human serum albumin (HSA). human immunoglobulin (IgG), and human fib-... 

Surrogates for in vivo permeability can be determined in situ or in vitro. Generally, these experiments are used to determine the permeability of drugs across the epithelial cell layer lining the G1 tract. 

In situ methods involve the external perfusion of an isolated segment of intestinal tissne." The rat has been shown to be an excellent model for human intestinal permeability." One of the principle advantages of the in situ method is that the intact rat intestinal tissne maintains a normal complement of influx and efQux transporters. Cephalosporins and beta-lactam antibiotics are known to be absorbed by oligopeptide transporters in the GI tract. The rat in situ permeability method was used to determine the saturable Michaelis-Menten-type kinetics for this class of drug molecules. In like fashion, the permeabilities of thymidine anti-viral drugs, like AZT, involving the nncleoside transporter were determined in situ. ... 

Beyerlein, 1., Amer, M.S., Schadler, L.S., and Phoenix, S.L., New methodology for determining in situ fiber, matrix and interface stresses in damaged multifiber composites, Sci. Eng. Composite Mater., 7, 151, 1998. 

To use this relationship to determine in situ relative density, it is necessary to take both stabilized and normal samples of the soil back to the laboratory. Samples are grouted in the lab at minimum and maximum density. These samples are tested and two points plotted on an arithmetic graph of density versus UC strength. The UC value of the stabilized field sample is also determined, and this point is plotted between the other two (it usually falls on or close to the line joining the first two points). The position of the point representing the field sample determines the relative density. 

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