Experimental Investigations

there was no experimental evidence for interface polymerization and precipitation or titania surface dissolution. Moreover, considerable deposition was found even at pzc and a considerable decrease of pH upon adsorption. Moreover, it was observed that the presence of the aqua complexes in the impregnating solution brings about an important shift of the pzc (iep) to lower (higher) values and an increase of the electroldnetic charge or f -potential values determined at various pHs. Finally, a value equal to about 2 was determined for the ratio amount of H+ ions released/amount of cationic species adsorbed . The above indicated the formation of rather mononuclear and perhaps a small quantity of ohgonuclear irmer-sphere complexes under our experimental conditions. Moreover, the value for the aforementioned ratio su ested a rather disubstituted local structure for the deposited Co(II) mononuclear precursor species. The DR spectra recorded after the equitibration of the suspensions and filtration also indicated the formation of surface inner-sphere complexes. 

In order to obtain results of more practically applicable value, in the investigation by Wu et al. L1811 the commercial Na HPO FLO crystalline and the corresponding mother liquor are taken directly from a plant producing inorganic salts as the testing materials, the chemical compositions of which are illustrated in Table 12.1. 

To ensure that all the overall crystal-growth rate coefficients are measured under the conditions without nucleation, the metastable region of the solution has to be determined first and therefore the solubility and super solubility need to be measured. 

For the measurement of solubility the traditional dissolution-equilibrium procedure is employed, i.e., put both the crystals and the mother liquor into a container submerged in a water bath continuously stirred, control the temperature inside the container rigorously at a given value, with the fluctuation no greater than +0.1°C. When the dissolution equilibrium is achieved, measure the concentration of the solute in the liquid phase as the solubility at the temperature given. The equilibrium condition is judged by the criterion that the relative deviation of the values obtained in, at least, three times of adjacent measurements is not greater than %c. 

The method used for the measurement of the metastable region is also the traditional one, i.e., using the light scattered by the newly formed fine crystals to detect the nucleation status. The experimental equipment is shown in Fig. 12.1. The water bath tank is surrounded with a light-proof black screen, with two windows vertical to each other with dimension of 2x3 cm for light beam casting and visual observation, respectively. To parallel the industrial condition of induced nucleation, all the measurements are carried out under conditions with the existence crystal seeds. 

For comparison, the experiments for measuring the overall crystal-growth rate coefficient are carried out in an impinging stream crystallizer (ISC) and a fluidized bed crystallizer (FBC). 

---

The experimental investigations are carried out in order to get an idea about the variations of the visibility of the indications during practical inspections. The specimen where a test piece with spare eroded artificial defects (Width 25 pm depth d = 30, 60, 120 pm) and other specimen with natural cracks, a forged steering lever and a weld. As an example, in Fig 4 the steering lever with 2 cracks can be seen and below the dependance on the visibilty of a weak indication and a part of the bright indications on the field strenght H. 

The calculation on the base of solution (2) and experimental investigations have allowed to choose some constructions of magnetic systems for retaining of a magnetic fluid on the transducer surface for magnetic and non-magnetic materials. 

In assessment of characteristics of measurement error all components of this error must be taken into account and supported by the results of experimental investigations. 

Experimental investigations in attestation of the procedures of testing are performed on real test objects or on physical model that is close to the real test object. 

Systematic experimental investigations of these transport effects on reaction rates can either be done by varying solvents in a homologous series to change viscosity without affecting other physicochemical or chemical properties... 

Experimental investigations of the model system of dye molecules adsorbed onto surfaces of polystyrene spheres have finuly established the sensitivity and surface specificity of the SHG method even for particles of micrometre size [117]. The surface sensitivity of die SHG process has been exploited for probing molecular transport across the bilayer in liposomes [118], for measurement of electrostatic potentials at the surface of small particles [119] and for imaging... 

One of Che earliest examples of a properly conceived experimental investigation of the flux relations for a porous medium is provided by the work of Gunn and King [53] on the dusty gas model equations, and the following discussion is based largely on their work. Since all their experiments were performed on binary mixtures, the appropriate flux relations are (5.26) and (5,27). Writing... 

It is apparent from items (l)-(3) above that linear copolymers-even those with the same proportions of different kinds of repeat units-can be very different in structure and properties. In classifying a copolymer as random, alternating, or block, it should be realized that we are describing the average character of the molecule accidental variations from the basic patterns may be present. In Chap. 7 we shall see how an experimental investigation of the sequence of repeat units in a copolymer is a valuable tool for understanding copolymerization reactions. This type of information along with other details of structure are collectively known as the microstructure of a polymer. 

Resonance, polarity, and steric considerations are all believed to play an important role in copolymerization chemistry, just as in other areas of organic chemistry. Things are obviously simphfied if only one of these is considered but it must be remembered that doing this necessarily reveals only one facet of the problem. Nevertheless, there are times, particularly before launching an experimental investigation of a new system, when some guidelines are very useful. The following example illustrates this point. 

An approach to copolymerization has been advanced by Price and Alfrey which attempts to both combine resonance and polarity considerations and accomplish the data reduction strategy of the last paragraph. It should be conceded at the outset that the Price-Alfrey method is only semiquantitative in its success. Its greatest usefulness is probably in providing some orientation to a new system before launching an experimental investigation. 

Polarization which can be induced in nonconducting materials by means of an externally appHed electric field is one of the most important parameters in the theory of insulators, which are called dielectrics when their polarizabiUty is under consideration (1). Experimental investigations have shown that these materials can be divided into linear and nonlinear dielectrics in accordance with their behavior in a realizable range of the electric field. The electric polarization PI of linear dielectrics depends linearly on the electric field E, whereas that of nonlinear dielectrics is a nonlinear function of the electric field (2). The polarization values which can be measured in linear (normal) dielectrics upon appHcation of experimentally attainable electric fields are usually small. However, a certain group of nonlinear dielectrics exhibit polarization values which are several orders of magnitude larger than those observed in normal dielectrics (3). Consequentiy, a number of useful physical properties related to the polarization of the materials, such as elastic, thermal, optical, electromechanical, etc, are observed in these groups of nonlinear dielectrics (4). 

Enzymatic Catalysis. Enzymes are biological catalysts. They increase the rate of a chemical reaction without undergoing permanent change and without affecting the reaction equiUbrium. The thermodynamic approach to the study of a chemical reaction calculates the equiUbrium concentrations using the thermodynamic properties of the substrates and products. This approach gives no information about the rate at which the equiUbrium is reached. The kinetic approach is concerned with the reaction rates and the factors that determine these, eg, pH, temperature, and presence of a catalyst. Therefore, the kinetic approach is essentially an experimental investigation. 

The use of impedance electrochemical techniques to study corrosion mechanisms and to determine corrosion rates is an emerging technology. Elec trode impedance measurements have not been widely used, largely because of the sophisticated electrical equipment required to make these measurements. Recent advantages in micro-elec tronics and computers has moved this technique almost overnight from being an academic experimental investigation of the concept itself to one of shelf-item commercial hardware and computer software, available to industrial corrosion laboratories. 

Swearingen, J. S. and Mafi, S., 1969. Experimental Investigation of Vibrations in High Speed Rotating Maehinery, ASME Paper No. 69 VIBR-58. 

Prust, H.W. Jr., Schum, H.J., and Behning, F.P., Cold-Air Investigation of a Turbine for High-Temperature Engine Application, II—Detailed Analytical and Experimental Investigation of Stator Performance, NASA, TN D-4418, 1968. 

Brown, Royce N., An Experimental Investigation of a Pneumatic Closcrt Loop Anti-Surge Control for Centrifugal and Axial Flow Compressors Master s Thesis, University of Wisconsin, Madison, Wisconsin, 1966,... 

Simon, H. and Bulskamper, A., On the Evaluation of Reynolds Numbei and Relative Surface Roughness Effects on Centrifugal Compressor Per formance Based on Systematic Experimental Investigation, ASME 8J-C,1 118, New York American Society of Mechanical Engineers, 1983. 

Baney, J.M., Hui, C.Y. and Cohen, C., Experimental investigations of a stress intensity factor based description of the adhesion of viscoelastic materials. Langmuir, 17(3), 681-687 (2001). 

Tipnis, S. K., Penny, W. R., and Fasano, J. B., An experimental investigation to determine a scale-up method for fast competitive parallel reactions in agitated vessels, AIChE Annual Meeting, St. Louis, November 1993. 

The effeet of temperature satisfies the Arrhenius relationship where the applieable range is relatively small beeause of low and high temperature effeets. The effeet of extreme pH values is related to the nature of enzymatie proteins as polyvalent aeids and bases, with aeid and basie groups (hydrophilie) eoneentrated on the outside of the protein. Einally, meehanieal forees sueh as surfaee tension and shear ean affeet enzyme aetivity by disturbing the shape of the enzyme moleeules. Sinee the shape of the aetive site of the enzyme is eonstrueted to eoirespond to the shape of the substrate, small alteration in the strueture ean severely affeet enzyme aetivity. Reaetor s stirrer speed, flowrate, and foaming must be eontrolled to maintain the produetivity of the enzyme. Consequently, during experimental investigations of the kineties enzyme eatalyzed reaetions, temperature, shear, and pH are earefully eontrolled the last by use of buffered solutions. 

As mentioned earlier, it is not feasible to generate test data for all possible combinations of load variations. However, there have been a number of experimental investigations of the problem and these have resulted in some very... 

Outside the jet and away from the boundaries of the workbench the flow will behave as if it is inviscid and hence potential flow is appropriate. Further, in the central region of the workbench we expect the airflow to be approximately two-dimensional, which has been confirmed by the above experimental investigations. In practice it is expected that the worker will be releasing contaminant in this region and hence the assumption of two-dimensional flow" appears to be sound. Under these assumptions the nondimensional stream function F satisfies Laplace s equation, i.e.. 

The last advantage, parameter variations, is in fact common to all the numerical models but is a main advantage over an experimental investigation, as the time effort for changing parameters is very small. 

---