II.—Cyanocarone

Clarke, Reginald W. L.; Lapworth, Arthur

doi:10.1039/ct9109700011

Cited by 10 publications

(16 citation statements)

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“…The BD state manifests a g ( r ) typical of a liquid (with a some evidence of undercooling evidenced by the shoulder to the second peak), whereas the M D state has clearly at least partly nucleated into a microcrystallite, evident in the peak at r = 1.60. The BD state at 4 = 0.527 is close to the compression glass-transition of a simple liquid, which occurs at 4 !z 0.55 [34]. However, there is no significant evidence of a glassy structure, which would be apparent in a split second peak in the pair radial distribution function.…”

Section: Resultsmentioning

confidence: 75%

Molecular and Brownian Dynamics Simulations of Self-Diffusion in Inverse Power Fluids

Heyes

Brańka

1994

Physics and Chemistry of Liquids

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We compare the structural, thermodynamic and dynamical behaviour of a model colloidal system with that of the equivalent atomic system using the simulation techniques of brownian dynamics and molecular dynamics. In the process we establish the important role made by solvent mediated many-body hydrodynamics on colloidal single particle motion on "short" and "long" time scales. The short and long-time self-diffusion coefficients of model stabilised colloidal particles were calculated at solids volume fractions up to 0.527 using a hydrodynamics-free Brownian Dynamics, ED technique with model colloidal particles interacting through a r -36 repulsive pair potential. We have improved the simulation technique to follow the self-diffusion process over several molecular diameters, required for the evaluation of the long-time diffusion coefficient. The simulation long-time diffusion coefficient follows closely the behaviour of the experimental short-time diffusion coefficient for volume fractions below ca. 0.4.

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Section: Resultsmentioning

confidence: 75%

Molecular and Brownian Dynamics Simulations of Self-Diffusion in Inverse Power Fluids

Heyes

Brańka

1994

Physics and Chemistry of Liquids

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“…In the opinion of Clarke [5] and Speakman [17] the combined cystine is decomposed into cysteine and cysteine sulfonate :…”

Section: Discussionmentioning

confidence: 99%

“…The changes in the elastic properties of wool, brought about by different reagents, are mainly due to the breaking of these disulfide crosslinkages. ' If wool is treated with sodium bisulfite, according to Clarke [5] and Speakman [17], the combined cystine undergoes the following reaction: In 1946, Carter, Middlebrook, and Phillips [4] summarized the results of previous investigations [7,8,12]. They came to the conclusion that not all of the combined cystine reacts in the same way with sodium bisulfite, but that cystine can be divided into different fractions.…”

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The Reaction of Combined Cystine of Wool with Sodium Bisulfite

Schuringa

Schooneveldt

Konings

1951

Textile Research Journal

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THE DISULFIDE cross-linkages in wool,~ due to the combined cystine, are of fundamental importance concerning the physical and mechanical properties of the wool. The changes in the elastic properties of wool, brought about by different reagents, are mainly due to the breaking of these disulfide crosslinkages. ' If wool is treated with sodium bisulfite, according to Clarke [5] and Speakman [17], the combined cystine undergoes the following reaction: In 1946, Carter, Middlebrook, and Phillips [4] summarized the results of previous investigations [7,8,12]. They came to the conclusion that not all of the combined cystine reacts in the same way with sodium bisulfite, but that cystine can be divided into different fractions. According to these authors, about 25 % of the cystine does not react with sodium bisulfite, another 25% gives combined a-aminoacrylic acid, and one-half of the cystine is converted into cysteine and cysteine sulfonate side-chains. From the latter fraction part of the cystine can be restored by rinsing with water. Moreover, Speakman [18] found that when human hair is reduced with sodium bisulfite the cystine cross-linkages can be restored by rinsing with a solution containing no oxidizing agent.In connection with the extensive application of bisulfite for various treatments of wool, it is very important to know which reaction takes place in the wool and how this reaction can be influenced.Therefore, we investigated the final effect of the reaction between wool and sodium bisulfite, and the influence of rinsing. Experimental Procedure and ResultsSamples of 400 mg. of woolen yarn, degreased by extraction with a mixture of trichloroethylene and ethanol, were first soaked for 30 min. at room temperature in 125 times their weight of 5 % sodium bisulfite at pH 5.2,* and then reduced in an identical solution which had been preheated in a boiling water bath to 92°-95°C and kept at that temperature for 30 min. Heating the solution in a water bath prevented it from reaching the boiling point. Boiling had to be prevented because dispersion of tiny wool particles by the movement of the liquid might cause errors in the analytical data.The bisulfite-treated wool was then subjected to the following aftertreatments: (a) no rinsing, immediate hydrolysis; ( b ) before hydrolysis, rinsing for 20 hrs. in 0.50~o sodium acetate adjusted to pH 5.2 by the addition of acetic acid; (c) before hydrolysis, rinsing for 20 hrs. in 95% ethanol. Two additional wool samples were reduced for 60 min. and two more for 90 min. In each case, one sample was hydrolyzed without rinsing and one was hydrolyzed after 20 hrs. of rinsing with the sodium acetate buffer solution.The hydrolyses essential for determining cysteine and cystine were carried out in open test tubes with 10 ml. of 6N sulfuric acid. Hydrolyzing under C02 atmosphere did not make any difference.Although after 5 hrs. of boiling the keratin had not been completely hydrolyzed to amino acids, hydrolyzing for more than 5 hrs. caused no change in the values found for cysteine...

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Two syntheses for 5,6-dimethoxy-2-methylfuro(2',3',7,8)chromone are described, and this compound is identical with isokhellin. Preparative methods for isokhellinone and several new compounds incidental to the synthesis of isokhellin are also reported.N THE COURSE of attempts to prepare the parent I dihydroxyfurochromone (I, R = H) from khellin (I, R = CHJ, Clarke andRobertson (1) found that, on being subjected to demethylation by means of boiling hydriodic acid, khellin gave rise to a somewhat resinous product from which only one crystalline phenolic substance could be OR 0 isolated. Methylation of this substance yielded a diniethyl ether (m. p., 176"), isomeric, but not identical, with khellin, for which the name "isokhellin" was suggested.l The formation of isokhellin in this manner could take place during the demethylation process by either of the following routes, viz.

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confidence: 99%