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Gilman [124] and Westwood and Hitch [135] have applied the cleavage technique to a variety of crystals. The salts studied (with cleavage plane and best surface tension value in parentheses) were LiF (100, 340), MgO (100, 1200), CaFa (111, 450), BaFj (111, 280), CaCOa (001, 230), Si (111, 1240), Zn (0001, 105), Fe (3% Si) (100, about 1360), and NaCl (100, 110). Both authors note that their values are in much better agreement with a very simple estimate of surface energy by Bom and Stem in 1919, which used only Coulomb terms and a hard-sphere repulsion. In more recent work, however, Becher and Freiman [126] have reported distinctly higher values of y, the critical fracture energy. ... [Pg.279]

Reinhoudt, Gray, Smit and Veenstra prepared a number of monomer and dimer crowns based on a variety of substituted xylylene units. They first conducted the reaction of 1,2-dibromomethylbenzene and a polyethylene glycol with sodium hydride or potassium Z-butoxide in toluene solution. Mixtures of the 1 1 and 2 2 (monomer and dimer) products were isolated and some polymer was formed . The reaction was conducted at temperatures from 30—60° and appeared to be complete in a maximum of one hour. The authors noted that the highest yield of 1 1 cyclic product was obtained with disodium tetraethylene glycolate instead of dipotassium hexaethylene gly-colate (see also Chap. 2) . Chloromethylation of 1,3-benzodioxole followed by reaction with disodium tetraethylene glycolate afforded the macrocycle (29% yield) illustrated in Eq. (3.20). [Pg.29]

Hirashita, T. Kinoshita, K. Yamamura, H. Kawal, M. Arai, S. J. Chem. Soc., Perkin Trans. 1, 2000, 825-828. The authors note that the lithium enolate decomposes in the absence of IiiCls. [Pg.21]

In 1888, Combes described condensation of 2,4-pentadione (acetylacetone) 5 with aniline 1 to provide enamine 6. Subsequent warming in sulfuric acid provided quinoline 7. An excellent study describing scope and limitations of the Combes reaction was published in 1928 by Roberts and Turner. The authors noted that the ease of... [Pg.390]

There is no intention to reflect negatively on any manufacturer s packing or trays (author note). [Pg.279]

The strength of the filler skeleton may be characterized by the complex dynamic modulus measured at low frequencies [24]. The authors note that when c > ccr the yield point should be viewed as a sum of two components ... [Pg.33]

C. Eaborn and S. H. Parker,Chem. Soc. London, 126 (1955). These authors note that similar eleavages have been effected in 4-8 hours with an excess of refluxing potassium hydroxide-methanol-water. [Pg.87]

Solutes will interact with the reverse phase surface in much the same way as they do with the silica gel surface. There will be basically two forms of interaction, by sorption and by displacement. Sorption interaction has been experimentally confirmed by Scott and Kucera (10) by measuring the adsorption isotherm of acetophenone on the reverse phase RP18 from a 40%w/v acetonitrile mixture in water. The authors noted that there was no change in the acetonitrile concentration, as the solute was adsorbed. Displacement interactions, although certain to occur, do not appear to have been experimentally demonstrated to date. [Pg.79]

The transition to turbulent flow occurred at Re of about 1,500. The authors noted that for smaller micro-channels, the flow transition would occur at lower Re. The early transition phenomenon might be affected by surface roughness and other factors. [Pg.109]

Table 6.6 also demonstrates extraordinarily high bubble growth rates of 94.63, 72.8 and 95.3pm/ms. For these three cases, the growth rates are two orders of magnitude higher than the other cases. The authors noted that it is unclear why the bubble growth rate for such cases is much higher than the other cases. [Pg.290]

Methyl parathion and methyl paraoxon concentrations were measured in the condensate from coastal fog in California. Levels ranged from 0.046 to 0.43 pg/L methyl parathion and from 0.039 to 0.49 pg/L methyl paraoxon. The authors noted that the transformation of the methyl parathion to the methyl paraoxon appeared to take place during atmospheric transport of methyl parathion away from the agricultural areas (Schomburg et al. 1991). [Pg.159]

Included in the table are data for L. scoparium obtained from five sites in Australia. The Australian material exhibited a level of a-pinene approaching that of the northern race from New Zealand, but was clearly characterized by the highest level of 1,8-cineole observed in the study, along with the highest value for total monoterpenes and lowest value for total sesquiterpenes. The authors noted the need for further taxonomic study, particularly of the Australian material. [Pg.22]

Although the results eu e equal as far as utility is concerned, we shedl continue to use our symbolism, for reasons which will become clearer later on. The following Table is a comparison of defect symbolism, as used by prior Authors. Note that our symbolism most resembles that of Kroeger, but not in aU aspects. These prior authors also considered other intrinsic defects that we have not touched, namely interstices and the so-called "anti-structure" occupation. [Pg.98]

You and co-workers have demonstrated a further application of NHCs in the kinetic resolution of formyl p-lactams ( )-265 [103]. Upon treatment with a chiral NHC, the Breslow-type intermediate is formed, followed by ring-opening of the P-lactam moiety, with subsequent trapping of the acylazolium intermediate leading to the enantio-enriched succinimide product 266 and resolved formyl P-lactam (which is reduced to its alcohol 267). The authors note that when R" = H, the products undergo racemisation readily, and this is a possible explanation for the lower levels of enantioselectivity observed in the succinimide products 266 (Scheme 12.60). [Pg.294]

This interpretation was supported by further investigations by GiacomelH and coworkers [73]. Racemic 4-phenyl-l-hexene was kineticaUy resolved by isomerization of the double bond using a catalyst system consisting of Al Buj, (R)-N,N-di-methyl-l-phenylethylamine and Ni(mesal)2. Very poor enantioselectivities (ee < 0.3%) were observed for both the isomerization product and the unreacted alkene. The authors note that it is essential to first react the alane with the chiral amine. No... [Pg.63]

The authors noted, however, that the separation of compounds into chemically similar classes considerably improves the construction of predictive BBB penetration models. [Pg.116]

Slemr et al. (2003) attempted to reconstruct the global trend of atmospheric mercury concentrations from direct measurements since the late 1970s, and suggested that atmospheric mercury concentrations increased in the late 1970s to a peak in the 1980s, then decreased until the mid-1990s, and have been nearly constant since then. The authors noted, however, that this trend is not consistent with... [Pg.3]

A monoclonal antibody-based ELISA has been utilized to determine ceftiofur levels in milk. The authors noted that matrix interference occurred, but a 1 100 dilution lowered the interference, and a 1 1000 dilution eliminated the matrix interference. Because of the high dilution, samples could not be measured below l.Opgkg The assay measured ceftiofur, its major metabolite desfuroylceftiofur, and ceftiofur protein conjugates and has been utilized to measure residues in milk from cows treated with therapeutic doses of the drug. The results from the incurred residue correlated well with a previous study using radiolabeled ceftiofur, confirming the detection of a metabolite that was not detected by HPLC. [Pg.702]


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