Importance of accurate measures

The chemical structures of five dextrans were partially determined by methylation, and found to be branched molecules having the following types of substitution (a) 6-0 and 3,6-di-O, (b) 6-0, 3-0, and 3,6-di-O, (c) 6-0,3,6-di-O, and 2,3-di-O, (d) 6-0, 4-0, and 3,4-di-O, and (e) 6-0 and 2,3-di-O. At 27° and pH 7 (external, Me4Si standard), the 13C shifts ofO-substituted, non-anomeric carbon atoms were C-2 (76.5), C-3 (81.6), and C-4 (79.5). The C-l resonances were also recorded, and may be used for reference purposes. Some variation of chemical shifts, relative to each other, was observed with changing temperature. (The work serves to emphasize the importance of accurately measuring the temperature of the solution when determining chemical shifts.102)... 

Intercomparison studies Because of the importance of accurate measurement of individual organics in air, there have been several intercomparison studies carried out in which a number of different laboratories have analyzed common samples, either synthetic or ambient air. In one such study (Apel et al., 1994), a... 

The measurement of dimensions is covered in chapter 7. It is, however, necessary to stress the importance of accurate measurement of the small cross-sectional area of tensile test pieces. 

Antoine Lavoisier with his wife. Lavoisier was born in Paris on August 26, 1743. From the beginning of his scientific career, Lavoisier recognized the importance of accurate measurements. His careful weighings showed that mass is conserved in chemical reactions and that combustion involves reaction with oxygen. Also, he wrote the first modern chemistry textbook. He is often called the father of modern chemistry. 

In this lecture, we have tried to summarize the importance of accurate measurements of the cosmic-ray composition in order to understand the nature of the cosmic-ray source. We recall that the discovery of the decrease of the relative abundance of secondary cosmic rays at high energies, i.e., the energy dependence of the propagation pathlength A(E), came as a complete surprise in the early 1970 s. However, this discovery provided major observational support to supernova shock acceleration models which, a few years later, predicted that the cosmic-ray sources should be characterized by relatively hard energy spectra. 

Measurements hence affect the daily lives of every European citizen. Often the results of measurements or chemical analyses are taken for granted, e.g. in our direct contact with measuring devices when we buy food or consume gas and electricity at home. The importance of accurate measurements creates particular concern in specific cases, e.g. when food is tested to check whether it has been contaminated by poisonous substances or when blood is analysed as part of a hospital check-up. 

The strength and elongation measurements are taken from autographic load-extension curves. Reduction of area is obtained from direct measurements of the test specimen. Because of the very small diameter of the wire and the importance of accurate measurements, a precise method of measuring the original and final diameters is employed. A microscope with cross hairs and a movable, calibrated stage is used to obtain diameter measurements accurate to 0.0001 in. 

Rate constants measured in discharge-flow systems depend upon measurements of (a) the velocity of flow u, and (b) the partial pressures of reactants. For a reaction first-order in atom concentration [A], the rate constant is given by = iJ d In [A]/dx = — (RTZFlAp)d In [A]/ dx, where SF is the total flow rate, A is the cross-section area of the flow tube, p is the total pressure, and x is the displacement along the tube axis. For simple reactions of higher overall orders, the dependences of rate constants upon the parameters SF, A, p and reagent flow rate F< are summarized in Table 4.2. The importance of accurate measurements of flow rates and of total pressure, particularly for reactions of overall second and third orders, is clear. For example, realistic random errors of 1 % in/ , and of 3% in SFand F<, lead to an error of 12% in Atj. 

The importance of accurate measurements of flow rates and total pressure in minimizing random errors in rate constants has been demonstrated. The most satisfactory method of reducing systematic errors arising from the physical behaviour of the flow system is to ensure conditions under which deviations from simple flow occur to a negligible extent. 

A vast majority of the kinetic measurements involving RO2 radicals has made use of the relatively intense UV absorption spectrum of these species in order to obtain time-concentration profiles. Moreover, for the study of peroxy radical selfreactions, absolute concentrations must be known in order to analyse second order decay profiles, indicating the importance of accurately measured absolute absorption cross sections. The cited peroxy radicals were generated by photolysis... 

One cannot overemphasise the importance of accurate abundance measurements and estimates of the errors involved in them. If suitable data are unavailable, or if their quality cannot be properly assessed, it is quite impossible to draw astrophysical conclusions. In this respect, systematic observation campaigns are preferable, collecting large and uniform samples of good quality. One might seek to achieve the aims on the following hst ... 

An element of quality assurance ensuring that all tests and measurements used to control and monitor the process or to test the product are capable of producing results that are accurate and precise to the extent dictated by importance of the measurement. 

Fowler P, Smith R, Smith K, Young J, Jeffrey L et al (2012) Reduction of misleading ( false ) positive results in mammalian cell genotoxicity assays. II. Importance of accurate toxicity measurement. Mutat Res 747 104-117... 

With the above introduction to the vacuum generation technologies, it is also important to accurately measure and to detect the level of the vacuum within a chamber. This section introduces the basic working principles of these devices covering the most common CVD systems. 

The measurement of temperature is one of the most common physical measurements routinely made. It is so common that it is often overlooked as a variable when complex biochemical reactions are being studied. This is unfortunate, because an error in the temperature of a reaction may produce a large error in the results that becomes apparent when the results are compared with those of known standard reactions. For example, if the rate of reaction of an unknown enzyme is being studied at a temperature that is different by 0.1°C from the temperature at which the standard reaction was measured, an error as large as 2-5% in the observed rate of reaction can occur. The experimental data would not correlate then with the known enzyme reaction rates. Such errors lead to confusion in determining mechanisms and to the large variations that occur even in normal values from one clinical laboratory to another. This article seeks to bring the importance of accurate temperature measurements to the attention of biomedical scientists. We will identify the latest methods of temperature measurement and control as well as new temperature fixed-point standards that are or will shortly become available. 

The importance of fouling measurement techniques using monitors is likely to increase as the competitive nature of the process and power industries intensifies. In cooling water applications more effective use of additives can be achieved through their use wdth reduced costs and less environmental impact, as a result of accurate assessment of the fouling problem. 

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