Investigation reproducibility

Fig. 2. The pulse sequence for the CP/MAS experiment. The values of the different time parameters depend on the relaxation behaviours and on the mobilities of the nuclei in the compounds investigated. (Reproduced with permission of Ref. I0))...

Figure 1. Schematic design of the experimental arrangement for fraotoemisslon investigation. (Reproduced with permission from Ref. 7. Copyright 1984 Plenum Press.)...

These bands were a matter of discussion for a long time until in 1954, for the first time, Sjostrand and Andersson used electron microscopy to investigate intercalated disks in ultrathin osmium tetroxide-fixed sections of the mouse heart revealing that the disks were indeed transverse cell boundaries. Subsequently, several investigators reproduced their finding [Lindner, 1957 Moore... 

Although the reaction of chlorine and bromine with phenothiazine has been long investigated, reproducible methods leading to well-defined halogenated derivatives were described only within the last 15 years. Even for products like 1,3,7,9-tetrachlorophenothiazine which were characterized in the earlier literature, the definitive demonstration of the positions occupied by the chlorine atoms was performed only recently, and the methods of preparation have been substantially improved. 

Fig. 8.7. Effect of a uniaxial stress of 50.88MPa parallel to the [111] axis on the LHeT absorption spectrum between 4.3 and 10.5 meV of a Ge Sb sample (spectral resolution 0.072 cm-1 or 9 ueV). The small lines denoted by greek letters, while very probably linked to Sb, have not been further investigated. Reproduced from [8]. Copyright 1996, with permission from Elsevier...

Fig. (21). Schematic representation of a PEM fuel cell set-up for in situ APXPS investigations Reproduced with permission from Ref. [206], 2013 Macmillan Publishers Limited.

Fig. 17.14 Drawing of the compression tool and the flow fleld replica for p-CT investigations—Reproduced from [17, 91] with permission of Springer...

Figure 12 Stress-temperature curves at constant pressure and length for an amorphous polyethylene network in the unswollen state. Values of the elongation a and of the nominal stress / are calculated using the rest length and the undeformed cross-section respectively, at the highest temperature investigated (reproduced by permission of Wiley from J. E.

Therefore an automatic method, which means an objective and reproducible process, is necessary to determine the threshold value. The results of this investigations show that the threshold value can be determined reproducible in the point of intersection of two normal distributed frequency approximations. 

In a mechanistic study, the aim is not to quantitatively reproduce an experiment. As a result it is not necessary to use the methods outlined above. The question here is what drives a reaction in a particular direction, or what would happen if the molecule is driven in different ways. The initial conditions are then at the disposal of the investigator to be chosen in a way to answer the relevant question, using a suitable spread of positions and energies. 

Many investigations are reported on azides of barium, calcium, strontium, lead, copper, and silver in the range 100 to 200°C (212 to 392°F). Time exponents were 6 to 8 and activation energies of 30 to 50 kcal/g mol (54,000 to 90,000 Btu/lb mol) or so. Some difficulties with reproducibility were encountered with these hazardous materials. 

It is not always practical or convenient to investigate corrosion problems in the laboratory. In many instances, it is difficult to discover just what the conditions of service are and to reproduce them exactly. This is especially true with processes involving changes in the composition and other characteristics of the solutions as the process is carried out, as, for example, in evaporation, distihation, polymerization, sulfona-tion, or synthesis. 

RMC can be selectively extracted into butyl acetate. Concentration coefficient 50 was achieved. Factors affecting accuracy and reproducibility of the proposed method were investigated. Method is simple and fast. Detection limit is 0,3 p.g/1 for P(V). 

The possibility of preconcentration of selenium (IV) by coprecipitation with iron (III) hydroxide and lanthanum (III) hydroxide with subsequent determination by flame atomic absorption spectroscopy has been investigated also. The effect of nature and concentration of collector and interfering ions on precision accuracy and reproducibility of analytical signal A has been studied. Application of FefOH) as copreconcentrant leads to small relative error (less than 5%). S, is 0.1-0.2 for 5-100 p.g Se in the sample. Concentration factor is 6. The effect of concentration of hydrochloric acid on precision and accuracy of AAS determination of Se has been studied. The best results were obtained with HCl (1 1). 

From this equation it is seen that parameters have been introduced into the QM-MM method, with K, L, M, and corresponding to the pseudo s orbital on the classical atom. These parameters can be optimized to reproduce experimental or high level theoretical data. Field et al. [9] perfonned extensive investigations of the values of these extra parameters and suggested that the parameters K, L, and M (i = 1,. . . , 4) can be set to zero and that should take a value of 5.0. These are generally the values used in most current QM-MM implementations that employ semiempirical methods in the quantum region. 

This chapter has only scratched the surface of the multitude of databases and data reviews that are now available. For instance, more than 100 materials databases of many kinds are listed by Wawrousek et al. (1989), in an article published by one of the major repositories of such databases. More and more of them are accessible via the internet. The most comprehensive recent overview of Electronic access to factual materials information the state of the art is by Westbrook et al. (1995), This highly informative essay includes a taxonomy of materials information , focusing on the many different property considerations and property types which an investigator can be concerned with. Special attention is paid to mechanical properties. The authors focus also on the quality and relutbility of data, quality of source, reproducibility, evaluation status, etc., all come into this, and alarmingly. 

When undertaking quantitative investigations it should be checked that the reaction on the TLC plate is complete — or at least stoichiometric and reproducible. In all cases it is also useful to apply reagent and sample solutions separately on neighboring tracks in order to be able to determine where the starting products appear in the chromatogram under the reaction conditions. In this way it is possible to decide whether additional by-products are produced. 

A precise mastery of the chromatographic process also requires that the relative humidity be controlled. There are sufficient examples demonstrating that reproducible development is only possible if temperature and relative humidity are maintained constant. The influence of the latter on chromatographic behavior can be investigated using the Vario KS chamber (Fig. 59). When the relative humidity IS altered it is possible that not only the zone behavior will be changed but also the order of the zones on the chromatogram (Fig. 60). 

---