Unusual Features

Cubitene is a diterpene present in the defense secretion of a species of African termite What unusual feature charactenzes the joining of isoprene units in cubitene" ... 

The isotherms of water on titania sometimes, but not always, exhibit an unusual feature (Dawson, Parfitt and co-workers ) in the form of a second knee X in the pjp° range 0-2 to 0-3, in addition to a rather rounded knee (cf. D in Figs. 5.21 and 5.22) at a lower relative pressure p/p° 0-05. 

Flow around a cylinder with axis normal to the flow provides a good example of the many unusual features of such flows. These are illustrated in Figure 3. 

C. Daniel, App/ications of Statistics to lndustria/Experimentation, ]oE Wiley Sons, Inc., New York, 1976. This book is based on the personal experiences and insights of the author, an eminent practitioner of industrial appHcations of experimental design. It provides extensive discussions and concepts, especially in the areas of factorial and fractional factorial designs. "The book should be of use to experimenters who have some knowledge of elementary statistics and to statisticians who want simple explanations, detailed examples, and a documentation of the variety of outcomes that may be encountered." Some of the unusual features are chapters on "Sequences of fractional repHcates" and "Trend-robust plans," and sections entided, "What is the answer (what is the question )," and "Conclusions and apologies."... 

The second unusual feature is that it has frequently been observed that the rubbers soften or reverse when subjected to high temperatures in a confined space. This is believed to be due to the presence of trapped moisture which, when not able to escape, causes hydrolysis of the polymer. 

The goal of this book is thus to assess progress in the field, to identify fruitful new research directions, to summarize the substantial progress that has thus far been made with theoretical studies, and to clarify some unusual features of carbon-based materials that are relevant to the interpretation of experiments on carbon nanotubes that are now being so actively pursued. A second goal of this book is thus to stimulate further progress in research on carbon nanotubes and related materials. 

Fig. 6.10. Two-dimensional simulations of the same arrangement of Fig. 6.9 show the predicted mean-bulk temperature contours at various times. The principal unusual feature is the hot region developed in the outside area due to simultaneous longitudinal and radial loading (after Graham [87G03]).

The dithionite ion has a remarkable eclipsed stmcture of approximate C2v symmetry (Fig. 15.32b). The extraordinarily long S-S distance (239 pm) and the almost parallel SO2 planes (dihedral angle 30°) are other unusual features. Electron-spin-resonance studies have shown the presence of the S02 radical ion in solution ( 300ppm), suggesting the establishment of a monomer-dimer equilibrium 8204 ... 

HCl addition usually proceeds through a carbocation intermediate, with the dominant product resulting from the most stable cation. Compare energies for the possible cations that can be obtained from isoprene (isoprene+H+). Rank them from most to least stable. Examine the geometries of the cations, and sketch one or more Lewis stmctures for each which are consistent with its geometry. Be sure to point out any unusual features. What factors might be responsible for the ordering of cation stability ... 

Previous considerations of pitting have been largely confined to metals and alloys that have a strong tendency to passivate, but since the pitting of copper has a number of unusual features it is appropriate to consider it in some detail. Reference to the potential-pH diagram for the Cu-H O (Section 4.2) system shows that in neutral solutions at the potentials encountered in oxygenated waters the stable form of copper is Cu O, and the corrosion resistance of copper thus depends upon whether or not the CU2O forms a protective film. 

Polymerization of amino acid iV-carboxyanhydrides to polypeptides exemplifies another interesting reaction which exhibits a number of unusual features. This reaction has been, and is still being, vigorously investigated by several independent groups of workers, and some recent results are particularly intriguing and deserve a detailed discussion. 

The stereoselectivity reverts in favor of the. rpn-isomer when bulky aldehydes such as 2,2-di-methylpropanal are employed8. This unusual feature is attributed to a higher reactivity of the (Z)-isomer in the equilibrating reagents15 or to the competition of the twist-boat transition states8. The diastereoselectivity decreases, when DMF is used as a solvent, or pyridine is added to the THF solution. Presumably, the complexation ability of the chromium reagent towards the aldehyde is decreased by these additives8. 

Nevertheless, the reaction in region B has other unusual features, notably in the pattern of substituent effects for 4-substituents this is the reverse of that observed in region A. From these and other considerations, Ridd s group (Challis and Ridd, 1962 de Fabricio et al., 1966) concluded that the nitrosating agent attacks the pro-tonated amine and is loosely associated with the aromatic ring in the transition state. 

An unusual feature of the geometry employed with reflection gratings is that the beam entering the camera may be squashed or expanded in the dispersion direction so that the beam size parallel to dispersion and along the slit respectively is... 

The unusual feature of the programs is the automatic processing based on sample class. The operator provides the relevant parameters to the system of programs using the program SETUP, which contains several fill-in-the-form screens. These parameters Include the "class" of the specimen and the required automatic processing, as described below, and other pertinent information such as Mark-Houwink parameters, vial number, injection number, and documentation of the experimental conditions under which the chromatogram is to be measured. 

Rh(TMP)- under these conditions, and in fact the selective activation of methane in benzene solution is a distinctive and unusual feature of this system, given that aryl C—H activation ought to be thermodynamically favored over alkyl C—H activation. The proposed linear transition state proposed in Fig. 8 is the key to this different reactivity. The corresponding trimolecular transition state for an arene would be expected to be bent, and this would be precluded by the bulky TMP... 

H2SO4 = 0.09 M, fi = 2.0 M). Arrhenius parameters are A 10 ° I.mole . sec and E 28.5 kcal.mole . Successive alkylation of the olefinic bond increases the rate of reaction. One unusual feature is the lack of any acidity dependence. This implies that Co(H20)g is the active oxidant and that a radical cation is formed initially the lack of any retardation by added Co(II) means that the initial step is irreversible, viz. 

The degradation of phenolic compounds by fungi may involve rather unusual features of which the following three are given as illustration ... 

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