Quantitative observations

The foregoing characteristics of the mechanical behavior of composite materials have been presented in a qualitative manner without proof. In subsequent chapters, these characteristics will be demonstrated to exist, and further quantitative observations will be made. 

Universality Fei genbaum s remarkable discovery consisted of the following two quantitative observations (see figure 4.6) ... 

Pometun, M.S., Chekmenev, E.Y., and Wittebort, R.J., Quantitative observation of backbone disorder in native elastin, J. Biol. Chem., 279, 7982-7987, 2004. 

Histopathological examination of tissues representative of the nervous system, including the brain, spinal cord, and peripheral nervous system Quantitative observations and manipulative test to detect neurological, behavioral, and physiological dysfuntions. These may include general appearance body posture... 

Work in several laboratories including our own has shown that polyunsaturation correlates with change in susceptibility to oxidant-mediated cytotoxicity and decreased cell survival (Wagner et al, 1993 Buettner, 1993 Wagner eta/., 1992 Spitz etal, 1992 Hart eta/., 1991 Guffyefa/., 1984). The quantitative observation on the relationship of fc/y-allylic positions and oxidizability provides a rational basis for understanding the role of polyunsaturation in oxidation-related cell death. 

Reactions are taking place around you all the time. It is important tto be aware of your surroundings and understand how humans interact with these surroundings. Your five senses allow you to observe the world in which you live. In the lab, you only use four senses to make observations. Nothing is ever tasted in the lab. Sometimes tools can extend your senses. When you describe the color, odor, or texture of an object, you are making a qualitative observation. Quantitative observations involve measured quantities, such as 15 g or 2.5 L. It is important not to confuse observations and interpretations in the lab. Observations are made using your senses interpretations are proposed explanations that are based on observations. In this lab, you will be making both qualitative and quantitative observations. 

These early applications of adsorption were based on intuition and not on a systematic study. It was in 1773 that Scheele made the first quantitative observations in connection with adsorption, whereas F. Fontana in 1777 reported his experiments on the uptake of gases from charcoal and clays. However, the modern application of adsorption is attributed to Lowitz. Lowitz used charcoal for the decolorization of tartaric acid solutions in 1788. The next systematic studies were published by Saussure in 1814. He concluded that all types of gases can be taken up by a number of porous substances and this process is accompanied by the evolution of heat (Dabrowski, 2001). 

Simon G, Maibach H. The pig as an experimental animal model of percutaneous permeation in man qualitative and quantitative observations—an overview. Skin Pharmacol Physiol 2000 13 229-234. 

From the considerations above, a further semi-quantitative observation can be made about molecular motion. Over short times, the velocity of motion of a molecule is correlated with its velocity a little earlier. Under these circumstances, the mean square displacement is of the form... 

The specific ability of certain finely divided, insoluble solids to stabilize foam has long been known [Berkman and Egloff, op. cit., p. 133 and Bikerman, op. cit., Chap. 11]. Bartsch [Kolloidchem. Beih, 20, 1 (1925)] found that the presence of fine galena greatly extended the life of air foam in aqueous isoamyl alcohol, and the finer the solids, the greater the stability. Particles on the order of 50 pm length extended the life from 17 seconds to several hours. This behavior is consistent with theory, which indicates that a solid particle of medium contact angle with the liquid will prevent the coalescence of two bubbles with which it is in simultaneous contact. Quantitative observations of this phenomenon are scanty. 

A more detailed quantitative observation for the system SDBS/IPA/dodecane/NaCl (Figure 6) is noteworthy. Three phases emerged... 

For quantitative observations, cyclic voltammetric (CV) measurements were performed over the triad of oxidation states, that is, anion, radical, and cation, available to these systems. The half-wave potentials for reduction and oxidation are summarized in Table 1. For all DTA radicals, oxidation is essentially reversible. Electrochemical reduction of radicals 10 and 12 is, however, almost irreversible, as in the case of radicals 3, 7, 10, and 12. Only for dithiazoles 13 and 33 <2004JA8256> are both the oxidation and reduction steps reversible. 

In the previous Sample Problems and Practice Problems, you were given the concentrations and volumes you needed to solve the problems. What if you did not have some of this information Chemists often need to know the concentration of an acidic or basic solution. To acquire this information, they use an experimental procedure called a titration. In a titration, the concentration of one solution is determined by quantitatively observing its reaction with a solution of known concentration. The solution of known concentration is called a standard solution. The aim of a titration is to find the point at which the number of moles of the standard solution is stoichiometrically equal to the original number of moles of the unknown solution. This point is referred to as the equivalence point. At the equivalence point, all the moles of hydrogen ions that were present in the original volume of one solution have reacted with an equal number of moles of hydroxide ions from the other solution. 

Nelson, H.G. and Williams, D.P., Quantitative observations of hydrogen-induced, slow crack growth in a low alloy steel, in Stress Corrosion Cracking and Hydrogen Embrittlement of Iron Base Alloys, Staehle, R.W., Hochmann, J., McCright, R.D., and Slater, J.E., Eds., NACE, Houston, TX, 1977, pp. 390-404. 

Making observations. Observations may be qualitative (the sky is blue water is a liquid) or quantitative (water boils at 100°C a certain chemistry book weighs 2 kilograms). A qualitative observation does not involve a number. A quantitative observation (called a measurement) involves both a number and a unit. 

Making observations is fundamental to all science. A quantitative observation, or measurement, always consists of two parts a number and a scale (a unit). Both parts must be present for the measurement to be meaningful. 

The literature has been surveyed to September 1966. The recent work (since 1959) is discussed in this section and organized according to the elements involved. The quantitative observations are summarized in Table I. 

We have seen that the method of preparation and the information provided by transmission electron microscopy may vary considerably depending on the type of study undertaken. At the same time, a considerable range of qualitative and quantitative observations is potentially available. It is thus essential to clearly define in advance the goal of the transmission electron microscopy observation (particle size, variations in local composition, etc.). 

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