Degree reproducibility

Fig. 15 Hyperbranched PG partially functionalized with quaternary and tertiary ammonium groups with different loading degrees. Reproduced with permission from [130]. Copyright 2008...

FIGURE 2. Calculated PRDDO geometry of vinylamine (115) type 118 shown in projection onto the CCN plane and dihedral angles shown along the N—C1 and C1=C2 bonds (distances in A, angles in degrees). (Reproduced with permission from Reference 201)... 

Figure 6.18 Xe-adsorption-dynamic curves of H-form mordenites with various silylation degrees. Reproduced with permission from [46-52], Copyright (1978-1989) Royal Society of Chemistry. O Unsilylated zeolite 0 zeolite silylated after thermal treatment 373 K (100° C) A 473 K (200°C) C 573 K (300°C) 0 673 K (400°C) hydrolysed and dehydrated zeolite after silylation...

RHF/3-21G transition structure for the ene reaction of ethene and propene. (Distances are in angstroms, angies in degrees. Reproduced from reference 19.)... 

Fig. 1Z7. Dynamic moduli at 23 °C of n-tetradecane solutions of SBS Kraton 1101 vs angular ii uency for various concentrations, as indicated in wt% the dependence on strain amplitude was checked by measurement of two amplitudes of cup oscillation sma symbob 1.1 degrees, large symbols 2 degrees. Reproduced from J Rheol [Ref. 369] by the courtesy of The American Institute of Physics, Woodbury, NY...

Ni content in the Fe-Ni produced in E/F versus calcine reduction degree. (Reproduced from Ref. 21 with permission of Wiley.)... 

F. 8.4 Optimized TS geometries for the Menshutkin reaction (a) in the isolated state and (b) in aqueous solution obtained by the FEG method. Bond length is in A and bond angle is in degree (Reproduced with permission from Hirao et al. [7]. Copyright 2001 Elsevier B.V.)... 

Scheme 1.5 Derived mechanism for a progressive fluorination degree (reproduced from [34] by permission of the American Chemical Society)...

The parameters in the original parameterization are adjusted in order to reproduce the correct results. These results are generally molecular geometries and energy differences. They may be obtained from various types of experimental results or ah initio calculations. The sources of these correct results can also be a source of error. Ah initio results are only correct to some degree of accuracy. Likewise, crystal structures are influenced by crystal-packing forces. 

The number and kind of defects in a given specimen, as well as the crystal habit and with it the proportion of different crystal faces exposed, will in general depend in considerable degree on the details of preparation. The production of a standard sample of a given chemical substance, having reproducible adsorptive behaviour, remains therefore as much an art as a science. 

From the earliest days, the BET model has been subject to a number of criticisms. The model assumes all the adsorption sites on the surface to be energetically identical, but as was indicated in Section 1.5 (p. 18) homogeneous surfaces of this kind are the exception and energetically heterogeneous surfaces are the rule. Experimental evidence—e.g. in curves of the heat of adsorption as a function of the amount adsorbed (cf. Fig. 2.14)—demonstrates that the degree of heterogeneity can be very considerable. Indeed, Brunauer, Emmett and Teller adduced this nonuniformity as the reason for the failure of their equation to reproduce experimental data in the low-pressure region. 

The first stage in the interpretation of a physisorption isotherm is to identify the isotherm type and hence the nature of the adsorption process(es) monolayer-multilayer adsorption, capillary condensation or micropore filling. If the isotherm exhibits low-pressure hysteresis (i.e. at p/p° < 0 4, with nitrogen at 77 K) the technique should be checked to establish the degree of accuracy and reproducibility of the measurements. In certain cases it is possible to relate the hysteresis loop to the morphology of the adsorbent (e.g. a Type B loop can be associated with slit-shaped pores or platey particles). 

Figure 6 shows the field dependence of hole mobiUty for TAPC-doped bisphenol A polycarbonate at various temperatures (37). The mobilities decrease with increasing field at low fields. At high fields, a log oc relationship is observed. The experimental results can be reproduced by Monte Carlo simulation, shown by soHd lines in Figure 6. The model predicts that the high field mobiUty follows the following equation (37) where d = a/kT (p is the width of the Gaussian distribution density of states), Z is a parameter that characterizes the degree of positional disorder, E is the electric field, is a prefactor mobihty, and Cis an empirical constant given as 2.9 X lO " (cm/V). ...

The 1993 ASHRAE Handbook—Fundamentals (SI ed.) gives material for integral degrees Celsius witb temperatures on the ITS 90 scale for saturation temperatures from —77.66 to 132.22 C. The same diagram reproduced here appears in that source. 

Tensile testing machine operated in a controlled temperature and humidity environment. Many applications involve bonding paper, which exhibits properties that are highly dependent on humidity. In addition, adhesive Tg values are often close to room temperature, and thus properties change substantially over even a few degrees. Therefore, for reproducible comparisons, temperature and humidity control is necessary. 

Systematic error, as stated above, can be eliminated— not totally, but usually to a sufficient degree. This elimination process is called calibration. Calibration is simply a procedure where the result of measurement recorded by an instrument is compared with the measurement result of a standard. A standard is a measuring device intended to define, to represent physically, to conserve, or to reproduce the unit of measurement in order to transmit it to other measuring instruments by comparison. There are several categories of standards, but, simplifying a little, a standard is an instrument with a very high accuracy and can for that reason be... 

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