McMahon studies

McMahon studied the effect of waxes on emulsion stability as monitored by the separation of water over time (46). The size of the wax crystals showed an effect in some emulsions but not in others. Interfacial viscosity indicated that the wax crystals form a barrier at the water/oil interface which retards the coalescence of colliding water droplets. Studies with octacosane, a model crude oil wax, show that a limited wax/asphaltene/resin interaction occius. A wax layer, even with absorbed asphaltenes and resins, does not by itself stabilize an emulsion. McMahon concludes that the effect of wax on emulsion stability does not appear to be through action at the interface. Instead, the wax may act in the bulk oil phase by inhibiting film thinning between... 

Ilinnels, M., and McMahon,]. E. (1997) Stakeholders and Market Transformation An Integrated Analysis of Costs and Benefits. Proceeding of the 1997 ACEEE Summer Study on Energy Efficiency in Buildings. Washington, DC American Council for an Energy -Efficient Economy. 

Finally, we should note that a particularly important area of application where density functional techniques, in spite of the deficiencies noted above, are virtually without competition is provided by biochemically relevant molecules, such as enzymes or nucleic acids. The techniques discussed in this section are virtually the only quantum chemical methods which can be applied in this context due to their outstanding price/performance ratio. For example, the 13C and 15N chemical shifts in bacteriochlorophyll A have been studied by Facelli, 1998, and in another investigation the 57Fe, 13C and 170 shifts in iron porphyrin derivatives gave important clues as to the structural details of these species, as shown by McMahon et al 1998. 

Lok ASF, McMahon BJ. Practice Guidelines Committee, American Association for the Study of Liver Diseases (AASLD). Chronic hepatitis B Update of recommendations. Hepatology 2004 39 857-861. 

Greenberg, B. D., McMahon, F. J. et al. (1998). Serotonin transporter candidate gene studies in affective disorders and personality promises and potential pitfalls. Mol. Psychiatry, 3(3), 186-9. 

McMahon We can play around with the IGF signalling system and get a smaller skeleton that way. We can also get a small skeleton by manipulating the Hedgehog signalling system. What isn t known is how those two systems talk to one another. I think it is an excellent system to study. If you want to pick a mammalian system, you want to have it such that the arrangement is easy to determine. It is a very stereotypical arrangement of growth and cell movements. 

Charache S, Terrin ML, Moore RD, Dover GJ, Barton FB, Eckert SV, McMahon RP, Bonds DR. Effect of hydroxyurea on the frequency of painful crises in sickle cell anemia. Investigators of the Multicenter Study of Hydroxyurea in Sickle Cell Anemia [see comments). 

McMahon et al. contributed to this field not only by revealing the electronic spectrum of S-37111 but also by elucidating — on the basis of studies with labeled compounds — the complex mechanism of the automerizations and isomerizations of the three C3H2 species S-2, T-36 and S-37.69,112 A complete record, including high level calculations, was published by McMahon.69... 

For gas-phase ir studies, it has been possible to show good correlation between Av h and (AHB) (Millen et ai, 1979). Even with condensed phases, this method is still fairly reliable, e.g. with alcohols (Piaggio et ai, 1983), and Av-AH correlations have recently been shown to hold for hydrogen-bonded ions (McMahon and Larson, 1984b). 

A large number of different techniques have been used to measure isotopic fractionation factors, and any method that can be used for measuring the equilibrium position of reaction (3) is appropriate. The discussion here will be limited to the more recent methods and those that have been used for studying hydrogen-bonded species. The discussion is further limited to fractionation factors for species in solution. Recent measurements (Larson and McMahon, 1986, 1987, 1988) of

hydrogen-bonded species in the... 

McMahon and Kebarle (1986) studied (MeF)2H as a model for (HF)2H . They thought this to be reasonable because the hydrogen bond of a proton bound to two methanols or dimethyl ethers, e.g. [MejO - H OMe2], gives cations with very similar energies to that of the hydrated oxonium ion [H2O H OHj] (Grimsrud and Kebarle, 1973 Meot-Ner, 1984). 

McMahon SA, Leonard GA, Buchanan LV, Giraud ME, Naismith JH. 1999. Initiating a crystallographic study of... 

Reactions corresponding to acidic solvolysis of acid halides have also been studied in the gas phase (McMahon, 1978). The results which bear close resemblance to solution processes are illustrated in (82) and (83). 

In some cases, the use of medium wattages (e.g., 450 W) is preferred over high-power microwave outputs (e.g., 700 W). This difference has been demonstrated in the ISH for detecting measles virus and chicken anemia virus in formalin-fixed, paraffin-embedded brain tissue (McMahon and McQuaid, 1996). In this study higher power outputs resulted in decreased sensitivity. Although the exact reason for this phenomenon is not known, it is hypothesized that optimal oscillation of dipolar molecules produces optimal thermal effects in tissue sections at medium wattages. 

Dermal. Medical case histories indicate that dermal exposure to silver or silver compounds for extended periods of time can lead to local skin discoloration similar in nature to the generalized pigmentation seen after repeated oral exposure. However, the amount of silver and the duration of time required to produce this effect cannot be established with the existing information (Buckley 1963 McMahon and Bergfeld 1983). Moreover, adverse effects such as argyria have not been associated with the use of silver sulphadiazine as a bactericidal agent (Fox et al. 1969). No studies were located regarding dermal effects in animals after dermal exposure to silver or silver compounds. 

These observations are particularly relevant to the experimental use of a-LTX in neurotransmission studies, since a-LTX has been shown in several systems to cause nonvesicular release by allowing leakage of cytoplasmic neurotransmitters (McMahon et al. 1990 Deri et al. 1993 Davletov et al. 1998). This flux could be mediated by the a-LTX channel itself, by local disruptions of cellular membranes, or by reversal of transmitter uptake pumps driven by Na+ gradient (see Section 3.4.3). Synaptosomes seem to be particularly sensitive to an increase in hydrostatic pressure, which may occur when influx of Na+ or Ca2+ leads to a concomitant influx of water. 

J3. Johnson, C. D., Kingsnorth, A. N., Imrie, C. W., McMahon, M. J., Neoptolemos, J. P., McKay, C., Toh, S. K., Skaife, P., Leeder, P. C., Wilson, P., Larvin, M., and Curtis, L. D., Double blind, randomised, placebo controlled study of a platelet activating factor antagonist, Lexipafant, in the treatment and prevention of organ failure in predicted severe acute pancreatitis. Gut 48, 62-69... 

D. McMahon, A collaborative study to evaluate quantitation utilizing different injection modes for capillary GC, J. Chromatogr. Sci., 23 137-143(1985). 

Finally, it should be noted that reduction of the carbonyl function by BH4, being an important synthetic reaction, has been studied recently for a limited number of substrates. It has been found that BH4 is not capable of reducing formaldehyde in the gas phase (Kayser and McMahon, 1984). However, substrates, such as difluoroformaldehyde, hexafluoroacetone and methylmaleic anhydride can be reduced by BH4 in the gas phase (van der Wei et a ., 1987). On the basis of 13C-labelling experiments, it has been... 

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