In situ Experiments

Study of the changes in the structure and morphology during fabrication of plastic is important from both practical and academic perspectives. For example, experiments carried out as a function of heat flow, relative humidity, and external stress yield, respectively, fundamental insights into the crystallization kinetics [107], hydration [79], and deformation [9,81] behavior of polymer chains. 

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Comparison with other Studies. How do the results of our investigation compare with similar studies Our results corroborate the data provided in a similar study of the effect of UV-B on primary productivity in the southeastern Pacific Ocean (35). In the latter study, it was noted that enhanced UV-B radiation caused significant decreases in the productivity of surface and deep samples. Compared to ambient, primary productivity decreased with increasing doses of UV-B. In another study in which in situ experiments using natural Antarctic phytoplankton populations, it was noted that incident solar radiation significantly depressed photosynthetic rates in the upper 10-15 meters of the water column (36). It was also found that the spectral region between 305 and 350 nm was responsible for approximately 75 percent of the overall inhibitory effect. 

Non-situ and ex situ studies can provide important information for understanding the properties of metal/electrolyte interfaces. The applicability of these methods for fundamental studies of electrochemistry seems to be firmly established. The main differences between common electrochemical and UHV experiments are the temperature gap (ca. 300 vs. 150 K) and the difference in electrolyte concentration (very high concentrations in UHV experiments). In this respect, experimental research on double-layer properties in frozen electrolytes can be treated as a link between in situ experiments. The measurements of the work functions... 

Figure 9 shows the electronic absorption spectrum of a PTTB film which has undergone extensive but incomplete reaction with bromine in a non-in-situ experiment. The absorption spectrum is that expected for a one-dimensional conjugated polymer. The sharpest absorption edge is at about 1490 nm (o.83 eV) and the absorption maximum is located at 1240 nm (1.0 eV). Thus, this material has a bandgap of about 0.83 eV. Note that two small... 

For the in situ studies, an electrochemical cell was designed to hold the nearly perfect copper crystal in contact with a thin layer (20 to 50 /Am) of electrolyte. Figures 34 and 35 show the cells employed in the ex situ and in situ experiments, respectively. In addition, Fig. 34 shows the voltammetric traces obtained for the deposition of T1 in the presence and absence of oxygen. In the... 

Ohzawa et al [112] studied the absorption, distribution, and excretion of 14C miconazole in rats after a single administration. After the intravenous administration of 14C miconazole at a dose of 10 mg/kg to the male rats, the plasma concentration of radioactivity declined biophysically with half-lives of 0.76 h (a phase) and 10.32 h (/ phase). After oral administration of 14C miconazole at a dose of 1, 3, or 10 mg/kg to male rats, the plasma concentration of radioactivity reached the maximum level within 1.25 h, after dosing and the decline of radioactivity after the maximum level was similar to that after intravenous administration. At a dose of 30 mg/kg, the pharmacokinetic profile of radioactivity in the plasma was different from that at the lower doses. In the female rats, the plasma concentration of radioactivity declined more slowly than that in male rats. The tests were conducted on pregnant rats, lactating rats, bile-duct cumulated male rats. Enterohepatic circulation was observed. In the in situ experiment, 14C miconazole injected was observed from the duodenum, jejunum, and/or ileum, but not from the stomach. 

A repetition of in situ experiments with the yellowhead wrasse, partially in response to the above criticisms, again showed that fish developed a learned aversion to otherwise palatable food that had been adulterated with 15P-PGA2 [99], This was presumably due to the emetic properties of PGA2. It was pointed out that methyl esters of prostaglandins are also known to possess emetic properties [104], and reasoned that if the 15-acetoxy ester inhibits the emetic properties of PGA2, then it is likely to be quickly lost because of its known lability, especially in the presence of coral esterase. Further, the acidic environment in the stomachs of predatory fish would promote hydrolysis of these labile esters. 

Additionally, an in situ experiment was performed to evaluate HBCD bioaccumulation. In site C5, clean barbels were exposed to the environment. As a control, the same experiment was performed in site C2. Twenty specimens of barbel were caged into each one of two stainless steel devices that were placed on the river-bed at the two locations. Nine specimens were immediately frozen to be analyzed as blanks. After 15 days of exposure, no mortality was observed in the cages. Table 4 shows levels of HBCD accumulated in the caged barbels exposed in sites C2 and C5. Accumulation at site C2 was negligible, as values measured after the exposure were even lower than those of the fishes not exposed. However, at site C5, after the... 

Catalysis is a dynamic process, and deeper insights into its phenomenology are extractable from in situ measurements than from characterizations of catalysts before and after catalysis. A number of notable in situ experiments have relied on modifications of standard TEM operations under vacuum. The main functions of the EM depend on a high-vacuum environment, and the pressure in a TEM is usually of the order of 10-7-10-6 mbar. Because the influence of the reaction environment on the structure and activity of a catalyst is critical (3), the high-vacuum environment of a conventional EM is inappropriate for investigating a catalytic reaction, as are characterizations of catalysts in post-reaction environments (e.g., when the catalyst has been taken out of the reaction environment and cooled to room temperature). 

Figure 10.34 C(1s) and 0(1 s) photoelectron spectra recorded at (2) 420 K and (3) 670 K during an in situ experiment in which the total pressure of 02 and CH3OH was 4 x 10-3 torr. Spectrum (1) was obtained after the model preparation of methoxy and formate groups on the surface. (Reprinted from Prosvirin, I.P et al., Kinetics and Catal., 44, 724-730, 2003. With permission from Springer Science and Business Media.)...

Understanding the factors influencing drug absorption and in particular predicting these values on the basis of pre-clinical in vitro and in situ experiments remains crucial to bringing safe and effective drugs to the market [3],... 

It should be apparent to the reader that the methods discussed in this and previous chapters are useful in both ex situ and in situ conditions. The later is more of a challenge to the experimenter, as conditions have to be maintained to avoid interference with what is being measured by the measurement itself. Although it does not deal directly with electrodeposition, the next section should be of interest, as we discuss a closely related issue in situ experiments in surface science. 

The calculated result is in good agreement with CO2 droplet dissolution rate obtained by in situ experiments (1.44 um/s, Brewer et al., 2002). 

Before discussing novel in situ ETEM developments for heterogeneous catalysis, we present some background information about various in situ developments in the materials sciences. A number of notable in situ experiments have relied upon modifications to the standard TEM operations. The main electron optical functions of the TEM, especially the electron gun, depend on a high vacuum environment. The typical 10 -10 mbar TEM environment is mildly reducing. With an ECELL, controlled chemically reducing atmospheres, such as... 

FujitaH (ed) 1985 In situ Experiments with HVEM (Osaka Osaka University Press) Gabor D 1948 Nature 161 111 Gai P L 1981 Phil. Mag. 43(4) 841... 

Generally, several protocols are used for the characterization of sohd-catalyzed reactions under batch reaction conditions by NMR spectroscopy. In ex situ experiments, the conversion of reactants adsorbed on the catalyst is carried out in an external oven and stopped after a given reaction time by quenching, for example, in liquid nitrogen. Subsequently, the reaction products formed on the catalyst surface are investigated at room temperature by use of a standard MAS NMR probe. This protocol is repeated with a stepwise increment of the reaction time at the same temperature or with a stepwise increment of the reaction temperature for the same duration. In an in situ experiment, the catalytic conversion of the reactants is measured inside the NMR spectrometer by use of a high-temperature MAS NMR probe. 

Landstrom, 0., Klockars, C.-E., Holmberg, K.-E. and Westerberg, S., "In Situ Experiments on Nuclide Migration in Fractured Crystalline Rocks", KBS TR 110, 1978... 

Biliverdin is converted to bilirubin in the second step, catalyzed by biliverdin reductase. You can monitor this reaction colorimetrically in a familiar in situ experiment. When you are bruised, the black and/or purple color results from hemoglobin released from damaged erythrocytes. Over time, the color changes to the green of biliverdin, and then to the yellow of bilirubin. Biliru-... 

Fig. 9. Schematic drawing of the apparatus for combined QEXAFS/XRD in situ experiments [adapted from Clausen et al. (53)].

Fig. 10. Apparatus for combined DEXAFS/XRD in situ experiments. [Adapted with permission from Nature, Ref. 53. Copyright 1991 Macmillan Magazines Limited.]...

Figure 16-5. Basic in-situ experiment to detect Pj( ,t) with the help of a miniaturized solid electrolyte (emf probe), (i, k) is a metallic or semiconducting solid solution which forms from the components i and k. (if) = reference electrode, tX = electrolyte.

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