Clarke studies

Clark, Studies on Oxidation-Reduction, Hygienic Laboratory Bulletin, 1028. 

Liddell P A, Sumida J P, Macpherson A N, Noss L, Seely G R, Clark K N, Moore A L, Moore T A and Gust D 1994 Preparation and photophysical studies of porphyrin-Cgg dyads Photochem. Photobiol. 60 537-41... 

The first mass spectrometric investigation of the thiazole ring was done by Clarke et al. (271). Shortly after, Cooks et al., in a study devoted to bicydic aromatic systems, demonstrated the influence of the benzo ring in benzothiazole (272). Since this time, many studies have been devoted to the influence of various types of substitution upon fragmentation schemes and rearrangements, in the case of alkylthiazoles by Buttery (273) arylthiazoles by Aune et al. (276), Rix et al. (277), Khnulnitskii et al. (278) functional derivatives by Salmona el al. (279) and Entenmann (280) and thiazoles isotopically labeled with deuterium and C by Bojesen et al. (113). More recently, Witzhum et al. have detected the presence of simple derivatives of thiazole in food aromas by mass spectrometry (281). 

The first mass spectrometric study of thiazoles was carried out by Clark et al. (115), who investigated the method of fragmentation of thiazole, and 4-methyl- and 2,4-dimethylthiazole. 

R. W. Hend, D. G. Clark, and A. D. Coombs, Toxicity of Purified DigficidjlEtherofBisphenolA Results ofPreliminaj Studies, SheU Report TLGR.0010.77, SheU Chemical Corp., Houston, Tex., 1977. 

Few other reactions of series of substituted pyridines have been investigated extensively. Dondoni, Modena, and Todesco have measured the rate of N-oxidation of a limited series of pyridines and found a good correlation with normal u-values with a p-value of — 2.23. The A-alkylation of pyridines with alkyl iodides in nitrobenzene has been studied by Brown and Cahn and by Clarke and Rothwell. Unfortunately, the only data available are for the parent compound and for alkyl derivatives, and, since the a-values for the various alkyl groups in a given position are substantially constant, this leaves a correlation of only three independent points. However, the rates of A-alkylation of the j8- and y-alkyl derivatives are so nearly equal that it appears as if no correlation existed. Clarke and Rothwell have also studied the alkylation with allyl bromide in nitromethane at various temperatures, and in this case a more extensive series is available. The authors state that no overall Hammett correlation is obtained however, the j8-substituted derivatives fall on one straight line and the y-derivatives on another one with a different slope. The data are shown in Fig. 2. The line for the j8-compounds, p = — 2.53 0.31, r = 0.95, is seen not to be very good the line for the y-derivatives, p = — 1.42 0.06, r = 0.99, is much more satisfactory. It does not seem likely that the discrepancy is due to the intervention of resonance effects, since in this case one would expect the correlation for the y-derivatives to be poorer than that for the j8-analogs. More extensive studies with a wider variety of substituents would seem very desirable. 

The principal use of gold is as a very thin coating about 0-05 /xm thick for electrical and electronic applications. Because of the thinness of gold electrodeposits, porosity must be very carefully controlled since seepage of corrosion products from substrate or undercoat exposed at these pores can have serious adverse effects on both appearance and electrical properties of the composite. The porosity can vary with the thickness of the deposit (Fig. 13.1), and with the type of plating bath and with its method of operation (Fig. 13.2), and the phenomenon has been extensively studied by Clarke and many other workers. 

Clarke s study of the porosity of gold deposits lasted for a decade . Reviewing the topic, Garte concluded that, to reduce porosity (1) the substrate surface should be smoothed chemically or electrochemically (2) certain undercoats are beneficial and (3) plating conditions must be tightly controlled . Better procedures led to a reduction of thickness requirements—e.g. from 5 to2-5 /im on connectors, provided other requirements are satisfied. 

EE) R. Vincent E.L. Clark, Shaped Charge Liner Studies Using Various Materials , DRD-444 (1973) (ConO FF) R.C. Dean B.E. Craddock, Hard Structure Munition-Phase IIC , GER-15945 (1973) (ConO GG) C.R. Hoggatt, E,S. Grubin W.H, Snyder, Performance of Testing Services on High Explosive Devices and the Reduction of Accumulated Data , DRI-4782-7309-F (1973) (ConO HH) D.R. 

Clark and Vermeulen (C8) later reported an extensive experimental study of power requirements in agitated gas-liquid systems. They correlated their data in dimensionless form as a function of fractional gas holdup, Weber number, and a geometrical factor. Their correlation is shown in Fig. 5. 

Stereochemical studies of metal carbonyl-phosphorus trifluoride complexes. R. J. Clark and M. A, Busch, Acc. Chem. Res., 1973, 6,246-252 (34). 

Chance, B., Leigh, J.S., Kent, J., McCully, K., Nioka, S., Clark, B.J., Marris, J.M., Graham, T. (1986). Multiple controls of oxidative metabolism in living tissues as studied by phosphorous magnetic resonance. Proc. Natl. Acad. Sci. USA 83,9458-9462. 

In sharp contrast to the stable [H2S. .SH2] radical cation, the isoelectron-ic neutral radicals [H2S.. SH] and [H2S. .C1] are very weakly-bound van der Waals complexes [125]. Furthermore, the unsymmetrical [H2S.. C1H] radical cation is less strongly bound than the symmetrical [H2S.. SH2] ion. The strength of these three-electron bonds was explained in terms of the overlap between the donor HOMO and radical SOMO. In a systematic study of a series of three-electron bonded radical cations [126], Clark has shown that the three-electron bond energy of [X.. Y] decreases exponentially with AIP, the difference between the ionisation potentials (IP) of X and Y. As a consequence, many of the known three-electron bonds are homonuclear, or at least involve two atoms of similar IP. 

Our results do not support the protein stress model. However, this model may apply in cases where stress is intermittent and results in tissue loss, as observed in the study of crows (Hobson and Clark 1992). Low protein levels throughout life after weaning may have produced overall slow and reduced rate of growth rather than tissue loss. Adult rats fed protein-deficient diets after maturation show systematic losses of nitrogen from most tissues that are in proportion to their turnover rates and masses (Uezu et al. 1983). Perhaps tissue nitrogen isotope enrichment may occur under these conditions. New experiments are needed to evaluate this hypothesis. 

Koberstein J.T., Gancarz I., and Clarke T.C., The effect of morphological transition on hydrogen bonding in PU Preliminary results of simultaneous DSC-FTIR experiments, J. Polym. Sci. B, 24, 2487, 1986. Skrovanek D.J., Painter P.C., and Coleman M.M., Hydrogen bonding in polymers 2. Infra red temperature studies on nylon 11, Macromolecules, 19, 699, 1986. 

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