Experimental procedure objectives

Our objectives in this section are twofold to describe and analyze a mechanical model for a viscoelastic material, and to describe and interpret an experimental procedure used to study polymer samples. We shall begin with the model and then proceed to relate the two. Pay attention to the difference between the model and the actual observed behavior. 

Much of our present day knowledge of sweetness intensity, both at the threshold level, where taste begins, and above the threshold level, derives from the application of psychophysical techniques. It is now evident that the psychophysical procedure used measure separate aspects of sweetness perception. Hedonic responses cannot be predicted from intensity of discrimination data, and vice versa. The taste-panel evaluation of sweetness is of fundamental importance in the development of worthwhile structure-taste relationships. Therefore, it is vital that the appropriate psychophysical method and experimental procedure be adopted for a particular objective of investigation. Otherwise, false conclusions, or improper inferences, or both, result. This situation results from the failure to recognize that individual tests measure separate parameters of sensory behavior. It is not uncommon that the advocates of a specific method or procedure seldom... 

Almost simultaneously with the first attempt to determine molecular weight from equilibrium sedimentation, Rinde tried to widen this method to include determination of the molecular weight distribution (MWD) of a polydisperse system (3). Unfortunately, this attempt proved to be more complicated and did not result in establishment of a reliable routine. Since the appearance of Rinde s dissertation in 1928, many investigators have tried to determine MWD. Most of these efforts, however, did not provide a successful comprehensive technique (4-16). This objective has been accomplished only in a few cases under very limited conditions, such as in case of a Gaussian or near Gaussian MWD, in which only characterizing parameters had to be determined. Scholte (17, 18) determined MWD by performing an experimental procedure based on several equilibrium experiments. 

In order to investigate the mystic experience, an experimental procedure was devised based on classical descriptions of contemplative meditation. This procedure can be described as one of perceptual concentration. An initial short-term experimental study showed that very striking changes in the perception of the self and of objects were possible through the use of this procedure, and there were also indications that analogues to the classical mystic experience could be achieved as well. The rationale, procedure, results, and conclusions of this experiment have been reported elsewhere. 

This method has considerable advantages over the free boundary methods with regard to experimental procedure. Possible objections to the method are (a) the calibration of the cell with material of different relative molecular mass and/or shape from the material under investigation is not necessarily valid and (b) entrapment of air bubbles in the pores or adsorption of the diffusing molecules on the pore walls will invalidate the results. 

Rice has suggested that in order to conserve historic colorants, it is necessary to know what constitutes the color, what chemicals affect it and how, and what factors cause it to fade or change (16), The specific objectives of this investigation were two-fold to discover dye types and characteristics in the voile fabric to discover if and how the fabric color changes in response to selected conditions it could have encountered in its wear life. This information could indicate possible factors to explain the types of discolorations on the dress. Experimental procedures and results for both objectives followed separate courses and therefore will be discussed separately. Results from the investigation of the first objective in part determined testing procedures for the second. 

The initial research objectives included developing a simple experimental procedure to study how the graft polymers, polystyrene, and a commercial phenol formaldehyde resin interact when combined with wood under heat and pressure. Two-ply lap shear test specimens were used for a comparative test. 

Whether the criteria for rejection are those recommended above or alternative criteria, it is important that the chosen criteria be used consistently. The criteria must be decided upon ahead of time selection of criteria after the measnrements have been made runs the grave risk of introducing bias. If a series of measnrements presents a problem that cannot be treated objectively with previonsly selected criteria, then if at all possible the entire series should be rejected and a new series of measnrements made after careful review of the experimental procedure to minimize the possibility of large errors, mistakes, or bias. 

These two objectives are discussed together because many of the selection criteria for screening compounds are important to fulfill both objectives, namely physical chemical properties and chemical purity and stability. Especially with respect to optimizability, a violation of the selection criteria discussed here is not a definite reason for exclusion, but it is a liability of the compound, which needs to be addressed during the optimization of the compound that follows the discovery of the hit. The more such liabilities a compound exhibits, the more difficult the optimization of a lead compound will be. Also, not every violation of a technology compatibility criterion is a hard reason for exclusion, but rather it increases the potential of a compound to cause artifacts under a certain assay technology appropriate experimental procedures are required to detect these artifacts. 

In this paper, a new computer-aided technique was presented, with which the experimental procedure of developing catalysts is scheduled sequentially. In each sequential step the neural networks model and multi-objective optimization are used to determine optimal design for the next experiment. The sequential method proved very efficient in developing catalysts for propane ammoxidation to acrylonitrile. And the yield of acrylonitrile corresponding to the best catalyst was up to 58.9%. 

The objective is to provide the reader with a broad view of the field but in enough detail to permit the synthesis of novel oligosaccharide constructs. The experimental procedures for key transformations are presented when available. 

It is the degree of validity of this assumption which will decide the extent to which the results of the different experimental procedures of measuring the donor and acceptor strengths of solvents are objective and consistent. Below, the factors that determine the assertion of the above condition will be considered. 

In many organic laboratory courses, instructors make part of the experimental assignments open-ended—encouraging the students to plan and carry out experiments with some independence. This is a desirable objective, but there is an element of risk if the experimental procedure has not been carefully checked procedures found in the literature are not always easily reproduced. One of the better sources of experiments is Organic Syntheses although the experiments are typically reported on a large scale, they may often be easily scaled down. The experiments that occasionally appear in the Journal of Chemical Education also deserve mention. 

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