Experimental procedure previous studies

Wear-Testing Apparatus and Experimental Procedures. To study the effect of temperature on the wear behavior of specimen polymers, the pin-on-disk type wear testing apparatus used in our previous work (] J was employed and the frictional force and wear depth of the flat ended polymer pins 3 mm in diameter were measured at a sliding speed of 0.1 m/s under a load of 10 N and at various experimentally possible disk temperatures up to 300. The disk was made of stain-... 

For a while till now, our research group has been involved in studies of the properties of limit flames. Most of the results reported in this chapter were obtained for propane flames, under normal atmospheric conditions, in 300 mm long channels, with a square cross-section. The experimental procedure was described previously [25]. A flame propagating through a stationary mixture in a quenching tube or quenching channel can be characterized by the parameters defined in Figure 6.1.1. 

The general experimental procedure employed in the study here has been described previously (7), thus only a brief overview is presented here. For all experiments, 45 mL deionized water and catalyst (50 mg Pd-black for 3-buten-2-ol and 25 mg for l,4-pentadien-3-ol) were added to the reaction cell. For ultrasound-assisted, as well as stirred (blank) experiments, the catalyst was reduced with hydrogen (6.8 atm) in water for 5 minutes at an average power of 360 W (electrical 90% amplitude). The reagents (320 mg 3-buten-2-ol or 360 mg l,4-pentadien-3-ol) were added to the reduced catalyst solution to achieve... 

The experimental apparatus has been described in detail elsewhere (11,12,22). In previous communications we have also described the porous silver catalyst film deposition and characterization procedure (11,12). Ten different reactor-cells were used in the present investigation. The cells differed in the silver catalyst surface area as shown in Table I. Catalysts 2 through 5 had been also used in a previous study (17). The reactor-cells also differed in the zirconia electrolyte thickness which could not be measured accurately. The electrolyte thickness varies roughly between 150 and 300 ym. 

By lifting the simplifying restrictions, the kinetic observations can be examined in more detail over much wider concentration ranges of the reactants than those relevant to pseudo-first-order conditions. It should be added that sometimes a composite kinetic trace is more revealing with respect to the mechanism than the conventional concentration and pH dependencies of the pseudo-first-order rate constants. Simultaneous evaluation of the kinetic curves obtained with different experimental methods, and recorded under different conditions, is based on fitting the proposed kinetic models directly to the primary data. This method yields more accurate estimates for the rate constants than conventional procedures. Such an approach has been used sporadically in previous studies, but it is expected to be applied more widely and gain significance in the near future. 

There has been a clear emphasis, in the CD literature, on II-VI semiconductors, mostly CdS, some CdSe, and recently on ZnS. This being the case, the reader may reasonably expect this chapter to be a voluminous one. On the other hand, many of these studies have focused on deposition mechanisms and kinetics (which are dealt with in the previous chapter), with photovoltaic cells, and, to a lesser extent, with quantum size effects, both of which will be dealt with in subsequent chapters. Two detailed descriptions of the experimental procedure (for CdS and CdSe) are given in Chapter 2. This leaves the obvious question What s left The present chapter will answer that question. This includes properties of the films not explicitly discussed in other sections, such as crystal structure, optical and electrical properties, as well as variants of the deposition process. Also, more detail will be given on non-Cd chalcogenides. In short, there is indeed much left. 

The apparatus used In this study was a single-pass flow system shown schematically In figure 2. It Is similar In principle to that used by Kumik et al. (8). The experimental procedure has been outlined In a previous publication (7 ). 

This conclusion was confirmed also by a different series of experiments elucidating the role of plastic deformations. The experiments were performed in the regime of practically uniform rather than local loading. To this end we employed the procedure developed to study the initiation and development of autowave processes under conditions of uniform compression (see Section VII). But whereas previously what were subjected to y radiation were massive samples under conditions of high static pressure (i.e., the stage of accumulation of active centers in the sample was preceded by plastic deformation during compression), in this work the experimental procedure was modified to fit the task formulated above. 

The hydrate and phenol clathrate equilibrium data of the water-carbon dioxide, phenol-carbon dioxide, and water-phenol-carbon dioxide systems are presented in Table 1 and depicted in Figure 2. In order to establish the validity of the experimental apparatus and procedure the hydrate dissociation pressures of carbon dioxide measured in this work were compared with the data available in the literature (Deaton and Frost [7], Adisasmito et al. [8]) and found that both were in good agreement. For the phenol-carbon dioxide clathrate equilibrium results, as seen in Figure 2, the dramatic increase of the dissociation pressures in the vicinity of 319.0 K was observed. It was also found in the previous study (Kang et al. [9]) that the experimental phenol-rich liquid-phenol clathrate-vapor (Lp-C-V) equilibrium line of the binary phenol-carbon dioxide system could be well extended to the phenol clathrate-solid phenol-vapor (C-Sp-V) equilibrium line (Nikitin and Kovalskaya [10]). It is thus interesting to note that a quadruple point at which four individual phases of phenol-rich liquid, phenol clathrate, solid... 

We performed extensive studies to determine the Cl-atom rate constant of benzene. n-Butane and ethane were among first molecules that were used as references to measure the relative rate constant of Cl-atom reaction of benzene. By the end of these experiments, the concentration of reference molecules reduced close to the detection limits whereas no decay of benzene outside the uncertainty limits was observed. Although the relative rate technique is particularly powerful in the measurement of reactions with comparable rate constants, for reactions with very different rate constants, this method is less accurate. Since it has become clear that the Cl-atom rate constant of benzene is slow, chloromethane, dichloromethane, and trichloromethane (chloroform) were used as references. These sets of experiments consisted of 20 individual experiments in which the concentration of hydrocarbons ranged from 10 to 15 mTorr and the concentration of CI2 varied from 10 to 100 mTorr. The relative rate constants for chloromethane and dichloromethane have been previously measured by Niki et al. [65]. Specifically, they were combined as a check on the experimental procedures. No difference in the values of the rate... 

In addition to structural analysis and purity evaluation, Raman spectroscopy can also be used to estimate the crystal size of nanostructured solids. In most cases size characterization using Raman spectroscopy is based on the phonon confinement model (PCM), which uses changes in Raman frequency and Raman peak shape to estimate the crystal size. Although several attempts have been made to relate confinement-induced changes in the Raman spectrum of ND to the crystal size, the agreement between calculated and experimental data and the accuracy of the fitting procedure are still unsatisfactory. A detailed discussion of the limitations of the PCM and the accuracy of previous studies on ND powders is given in Ref [86]. 

Bromides and Iodides. The absorption spectra of the gaseous rare-earth halides were measured with a Cary 14 H spectrophotometer. The experimental procedure has been described previously 11). In this study a double furnace was used, allowing the rare-earth halide vapor to be heated to a higher temperature than the solid or liquid and allowing a baseline determination at the temperature of interest. In addition, a 0 0.1 full scale optical density slidewire was employed with the Cary... 

In this article, examples are chosen from recent literature to highlight progress in the NMR study of biological materials. Many emphasise the need for a careful choice of experimental procedure and/or instrumental design. The field is now expanding and too large to cover comprehensively, but several review articles on previous work are available e.g. enzymes [9-12], protein structure [13-16], interactions of biological molecules [17-19], and medicinal chemistry [20]. 

Detailed experimental procedures for obtaining infrared spectra on humic and fulvic acids have been reported previously 9,22,25-26) and will be briefly described here. Infrared spectra were taken on the size-fractionated samples by using a Fourier transform infrared spectrometer (Mattson, Polaris) with a cooled Hg/Cd/Te detector. Dried humic and fulvic materials were studied by diffuse reflectance infrared spectroscopy (Spectra Tech DRIFT accessory) and reported in K-M units, as well as by transmission absorbance in a KBr pellet. Infrared absorption spectra were obtained directly on the aqueous size-fractioned concentrates with CIR (Spectra Tech CIRCLE accessory). Raman spectra were taken by using an argon ion laser (Spectra-Physics Model 2025-05), a triple-grating monochromator (Spex Triplemate Model 1877), and a photodiode array detector system (Princeton Applied Research Model 1420). All Raman and infrared spectra were taken at 2 cm resolution. 

The fortunate fact that a number of the biochemical units are conjugated heterocycles has permitted the first theoretical unraveling of problems connected with their electronic structure in the framework of the 7r-electron approximation. However simple the procedures utilized, a careful analysis of the results has allowed the interpretation of a considerable body of experimental facts as well as a number of predictions later confirmed by subsequent experimentation 0. Although these results have survived the test of the successive refinements of the 7r-electron theories and have been complemented by the introduction of a simple representation of the a-framework, the possibilities of treating the a and 7r electrons simultaneously on an equal footing had to be explored in order to establish the theory on a firmer basis and also to gain further insight into some fine features of electronic properties which are otherwise inaccessible. Thus, the first outcome of the penetration of all-valence and all-electrons methods into biochemistry has been to deepen and refine previous studies. 

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