E. Wiedemann: Elektrophoresen

Cremer, H. D.

doi:10.1007/bf01838037

Cited by 3 publications

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“…(b) The partial pressure of the product gas in the sample environment should be as low as possible especially for reversible reactions [9][10][11][12][13][14];…”

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confidence: 99%

The measurement of meaningful activation energies

Reading

Dollimore

Rouquérol

et al. 1984

Journal of Thermal Analysis

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The uncertainty surrounding the significance of the measured kinetic parameters of solid state decomposition reactions is discussed briefly. Some suggestions are made about what precautions should be taken in order to favour the measurement of undistorted results. Some criteria are proposed for deciding whether a measured E value can be considered to have its usual meaning. The results of a series of experiments aimed at measuring the activation energy of the decomposition of calcium carbonate using a variety of methods, sample sizes and experimental conditions are presented. These results are compared with results found in the literature and it is concluded that it is possible to measure a reproducible value for E and it is tentatively proposed that this value is meaningful in terms of the energy barrier model of chemical reaction kinetics.When the Arrhenius equation is applied to solid state decomposition reactions the following expression is usually employed d_~ = f(e)Ae_E/R T (1) dtwhere t = time, 7" = absolute temperature, e = fraction decomposed, f(e) some function that is characteristic of the way in which the reaction proceeds, A = the preexponential factor, and E = the activation energy. Accordingly the influence of temperature on the reaction rate is expressed through the value of a single parameter, E. The meaning of E is generally interpreted in terms of the well known energy barrier model of chemical reaction kinetics and a given chemical reaction should have a characteristic "energy barrier" or activation energy. However, Dollimore, Galway and Brown in their recent review of reactions in the solid state [1] noted that "the kinetic parameters most frequently used to provide information about the (reaction) step identified as rate limiting are A and E. Values for nominally the same chemical change J. Thermal Anal. 29, 19B4

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“…(b) The partial pressure of the product gas in the sample environment should be as low as possible especially for reversible reactions [9][10][11][12][13][14];…”

mentioning

confidence: 99%

The measurement of meaningful activation energies

Reading

Dollimore

Rouquérol

et al. 1984

Journal of Thermal Analysis

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“…They brought forward no evidence that the dye is specific for proteins, and indeed they noted that both dextran and paper can in certain circumstances be coloured by it. Cremer and Tiselius (1950) gave a special method for removing the colour from paper while leaving it in protein. Geschwind and Li (1952) showed that certain amino-acids and peptides on paper chromatograms give a blue coloration with bromophenol blue.…”

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confidence: 99%

Ovule-gall stimulating a large fake fruit onMiconia chamissoisNaudin (Melastomataceae): a structural overview

Bomfim

Kuster

Caetano

et al. 2021

Botany

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The developmental processes of galls are better known when induced on vegetative organs, while they have hardly ever been described for reproductive ones. Herein, galls induced by Allorhogas uberlandiensis (Hymenoptera) on ovules of Miconia chamissois (Melastomataceae) were analyzed in terms of morphological, anatomical, histochemical and cytological characteristics. Galls are induced on the ovules before fertilization, acting as a physiological seed. Therefore, the ovary grows and develops into a fruit-like gall. The ovule-galls are on average 20 times larger than the seeds, and fruit-like gall volume is on average 5.4 times larger than that of mature fruits. These are related to cell hypertrophy and tissue hyperplasia in the host organ. There is a typical nutritive tissue formation in the ovule-gall with lipid, protein and pectin storage, as well as a storage tissue close to the epidermis. This nutritive tissue shows a smooth endoplasmic reticulum, multivesicular bodies and mitochondria-rich cells. After gall induction, all the ovules degenerate and ovary and hypanthium hypertrophy to form the fruit-like gall. The fruit-like galls form a physical barrier blocking the anthesis, preventing fertilization and keeping only ovule-galls. Our study shows that the A. uberlandensis galling insect may reduce the reproductive success of Miconia chamissois, thus acting as a biological control agent for this host plant population.

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“…Cremer gehörte damit zum “Uran‐Kreis” um Otto Hahn. In einem Rückblick im Jahr 1989 nahm sie Stellung “Zur Geschichte der Entfesselung der Kernenergie” 45…”

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Die Entdeckung der Gaschromatographie

Struppe¹

2011

Nachr Chem

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E. Wiedemann: Elektrophoresen

Cited by 3 publications

References 0 publications

The measurement of meaningful activation energies

The measurement of meaningful activation energies

Ovule-gall stimulating a large fake fruit onMiconia chamissoisNaudin (Melastomataceae): a structural overview

Die Entdeckung der Gaschromatographie

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