Experimental results and discussions

19 The reflectivity of the intensity grating. and of the polarization grating,, as a function of sample temperature. At about T=50°C, the reflectivities are equal, and this is the VPC temperature Typc-After Ref. 4. 

Now we are going to give a physical insight into an origin of the mechanisms responsible for experimental results mentioned above. The physics of the temperature tuning of the VPC can be qualitatively understood in the framework of the model presented in the Section 12.1. The amplitude of the DFWM signal can be written as  

The A component is then responsible for intensity grating efficiency, and xVin the component is responsible for the polarization grating efficiency. Therefore, the conjugation efficiencies for two different DFWM configurations are 

On the other hand, heating of the sample results in a higher rate of thermal disorientation of molecules and, hence, distorts the polarization grating and decreases Rp . At some temperature T,p., the stationary values of and Rp,j are equal to each other. In this case, pure VPC is realized. 

Experimental Results and Discussion 3.2.1. Homogeneous Charge Transport 

The influence of sulphuric acid concentration on charge transport rates for a series of osmium loadings, 25 5, is shown in Table 8.2. As noted previously, the rate of charge transport can be limited by one of three processes  

The rate of polymer chain motion required to decrease the intersite separation allowing electron self-exchange to occur 

For 20 n 10 in a 1.0-M electrolyte, Dct(CW) increases with increasing osmium loading. a(CV) is large and coupled to positive entropy terms. Z)cT-(CV) decreases for = 5, with an associated decrease in E iCY) to 25 kJ/mol, which is coupled to a negative entropy term. This suggests that for low loadings. 

FIGURE 8.12. Temperature dependence of Dct as measured from chronoamperometry in 1.0 M HCIO4. (From Ref. 58.) 

Basis of Using j so to Distinguish Between the Order/Disorder and Displacive Mechanisms 

In terms of a provisory conclusion, it takes a few weeks to determine a complete family of cure-time curves using the isothermal apparatus because each point has to be obtained separately [1]. Another disadvantage with the method is that the scatter in the data is too high, especially at low levels of cure. There is obviously a need for a faster and better technique. 

The reactor is inserted in region A of the solenoid bore (Fig. 11.1). Experiments are first made to measure the liquid holdup, the pressure drop and the wetting efficiency in the absence of magnetic fields. A sufficient time is allowed for the system to reach steady state before measurements are acquired. Experimental data are compared with the predictions of the Holub et al. [20] modeL Eigures 11.3a and b show the experimental data versus Holub s model for the trickle-flow regime with the magnetic field off. The slit model restores the hydrodynamic behavior pretty well in terms of pressure-drop and liquid-holdup variations. 

Turning the magnetic filed on yields, in region A, a product gradient of 650TV m at 9T (Fig. 11.1). The magnetic body force is calculated for (diamagnetic) water 

Improvement of wetting efficiency due to the magnetic field is directly related to simultaneously increasing liquid holdup as shown earlier for the air-water sys- 

To assess the phenomenology of existing wetting-efficiency correlations to handle the change of gravity conditions, we chose to simulate an amended version of the Al-Dahhan and Dudukovic [23] wetting-efficiency correlation  

A deep crevice was formed at the aluminum/copper interface. Close to the crevice, aluminum has a bright color, while except in this zone it seems to be covered by an oxide film over its whole surface, which is in good agreement with previous hypotheses concerning a passive state for aluminum in the couple. The bright color suggests that the crevice was at least partially related to the dissolution of the aluminum close to the interface. 

An orange-brown ring about 50 pm thick occurred all around the aluminum/copper interface. It was located on the aluminum material at a distance of about 150 pm from the interface. The ring was analyzed by energy-dispersive spectroscopy as being copper and is attributed to the deposition of copper coming from the dissolution of the aluminum/copper interface. This copper deposition will not be analyzed in the present work. 

Observations of the morphology of the aluminum/copper interface after immersion in the electrolyte suggest that corrosion 

from these results, a two-step mechanism is proposed to explain the corrosion phenomena observed on the aluminum/copper model couple  

Such phenomena are not dependent on the scale of the events and the two-step mechanism could explain the corrosion mechanisms in commercial alloys such as AA2024. Indeed, the results showed that the most significant feature was the current distribution, which provokes the increase of oxygen reduction at the interface and thus induces a strong variation of the pH of the electrolyte. This study shows that a simple model (pure aluminum/pure copper) is relevant for the study of what happens in copper-rich aluminum alloys and also underlines the specific and important role of the aluminum/copper interface. This feature caimot be observed if the galvanic coupling is studied in the usual way with two independent electrodes in the same solution. 

---

The majority of researchers, however, are inclined to believe that the tantalum reduction process takes place in a single step. Experimental results and discussions confirm that tantalum is reduced from fluoride, fluoride-chloride and oxyfluoride melts containing K2TaF7, via a single stage in which five electrons are transfered [546 - 548] ... 

The subsequent chapters will describe various quantum-chemical methods, compare them to experimental results and discuss their applications to such biological systems as amino acids, peptides, carcinostatic drugs, and DNA fragments. Proteins and large DNA fragments cannot be treated as yet with quantum-chemical methods, due to their size, but progress is being made continuously. 

On the basis of these experimental results and discussion, we tried to establish a convenient and useful method for quantitative evaluation of the molecular orientation in thin LB films using FT-IR transmission and RA spectra. Here, we assume a uniaxial orientation of the transition moment with an angle < > around the normal axis, Z, to the LB film surface i. e. the XY plane (Figure 8). In this case, the ratio of the absorbance of a particular band in the transmission spectrum, AT, to that of the same band in the RA spectrum, AR, is given by... 

Ramesh NS, Rasmussen DH, Campbell GA (1994) The heterogeneous nucleation of microcellular foams assisted by the survival of microvoids in polymers containing low glass-transition particles. 2. Experimental results and discussion. Polym Eng Sci 34 1698-1706... 

THE EXPERIMENTAL RESULTS AND DISCUSSION 2.1. JT complex in a site of cubic (trigonal) symmetry... 

EXPERIMENTAL RESULTS AND DISCUSSION 11.3.1 Intensive fluctuation region... 

Magnetic properties of antiferromagnetic MnF2 in the vicinity of the spin-flop transition. Experimental results and discussion [1-3]... 

Gandek, T.P., Hatton, T.A. and Reid, R.C., 1989, Batch extraction with Reaction Phenolic Antioxidant Migration from Polyolefins to Water. 1. Theory, and Batch extraction with Reaction Phenolic Antioxidant Migration from Polyolefins to Water. 2. Experimental Results and Discussion. Industrial Engineering Chemical Research, 28 1030-1045. 

---