Radiation-induced reactions with cellulose. VII. Effect of temperature and substituted styrenes in the copolymerization process

1970 ◽  
Vol 23 (6) ◽  
pp. 1163 ◽  
Author(s):  
S Dilli ◽  
JL Garnett
Keyword(s):  
Reaction Mechanism ◽  
Temperature Dependence ◽  
Effect Of Temperature ◽  
Methoxy Derivative ◽  
Temperature Range ◽  
Hammett Constants ◽  
Radiation Induced ◽  
Radiation Induced Grafting ◽  
Electron Withdrawing Substituents

The temperature dependence of the radiation-induced grafting of styrene to cellulose has been studied. The system cellulose-styrene-methanol was examined in the temperature range from 40° to -196° in order to observe possible ionic contributions to the reaction mechanism. This effect was further investigated using a series of substituted styrenes containing both electron-donating and electron- withdrawing substituents. The 17 monomers used included o-, m-, and p-mono- halogenated styrenes, a number of alkylstyrenes and the p-methoxy derivative. An attempt has been made to correlate the grafting results with the Hammett constants for the substituent. The consumption of monomer during grafting of styrene to cellulose has also been investigated.

scholarly journals The temperature-dependence of adenylate cyclase from baker's yeast

1979 ◽  
Vol 181 (3) ◽  
pp. 539-543 ◽  
Author(s):  
J Londesborough ◽  
K Varimo
Keyword(s):  
Reaction Mechanism ◽  
Adenylate Cyclase ◽  
Temperature Dependence ◽  
Reaction Rate ◽  
Arrhenius Plot ◽  
Maximum Velocity ◽  
Michaelis Constant ◽  
Arrhenius Plots ◽  
Temperature Range ◽  
Membrane Bound

The Michaelis constant of membrane-bound adenylate cyclase increased from 1.1 to 1.8 mM between 7 and 38 degrees C (delta H = 13 kJ/mol). Over this temperature range, the maximum velocity increased 10-fold, and the Arrhenius plot was nearly linear, with an average delta H* of 51 kJ/mol. The temperature-dependence of the reaction rate at 2 mM-ATP was examined in more detail: for Lubrol-dispersed enzyme, Arrhenius plots were nearly linear with average delta H* values of 45 and 68 kJ/mol, respectively, for untreated and gel-filtered enzymes; for membrane-bound enzyme, delta H changed from 40 kJ/mol above about 21 degrees C to 62 kJ/mol below 21 degrees C, but this behaviour does not necessarily indicate an abrupt, lipid-induced, transition in the reaction mechanism.

Electrolytic Separation of Deuterium; Effect of Temperature

1963 ◽  
Vol 18 (3) ◽  
pp. 347-350 ◽  
Author(s):  
M. S. Raman ◽  
R. Kumar ◽  
R. L. Datta
Keyword(s):  
Mild Steel ◽  
Cathode Material ◽  
Temperature Dependence ◽  
Temperature Coefficient ◽  
Separation Factor ◽  
Effect Of Temperature ◽  
Temperature Range ◽  
Nickel Silver ◽  
Electrolytic Enrichment ◽  
Separation Factors

The effects of cathode material and temperature on the separation factor in the electrolytic enrichment of deuterium are investigated in the temperature range 30°—60°C. Mild steel cathodes give separation factors higher than those for nickel, silver, platinum and tin, whereas an alloy of mild steel +7.85% tin gives still higher separation factors. The temperature coefficient of the separation factor (da/dT) for cathodes of tin and for an alloy of mild steel + tin (62.3%) is positive, whereas for other cathodes studied, da/dT is negative. The temperature dependence of the separation factor is decreased by alloying mild steel with tin. It becomes zero for the alloy with 39.5% tin.

Die Temperaturabhangigkeit der Fluoreszenzquantenausbeuten von Donator-Akzeptor-substituierten trans-Stilbenen in Losungsmitteln unterschiedlidier Polaritat

1981 ◽  
Vol 36 (6) ◽  
pp. 626-629
Author(s):  
D. Gloyna ◽  
I. Gryczyński ◽  
A. Kawski
Keyword(s):  
Quantum Yield ◽  
Temperature Dependence ◽  
Rate Constant ◽  
Fluorescence Quantum Yield ◽  
Activation Energies ◽  
Solvent Interaction ◽  
Temperature Range ◽  
Hammett Constants ◽  
Donor Acceptor ◽  
Solute Solvent Interaction

Abstract The temperature dependence of the fluorescence quantum yield of donor-acceptor-substituted trans-stilbenes (1) in n-heptane, toluene and dimethylformamide (DMF) in the temperature range of 5-70 °C is due to twisting of the excited Si state to the perp.-S1 state. Twisting and fluorescence are the predominant deactivation processes. Within the series of 4'-acceptor-substituted substances 1g, 1b, 1h- 1k, the activation energies, Etp, in n-heptane and DMF are correlated with the Hammett constants atp of the acceptor in a way comparable to the correlaton between the twisting rate constant kt„ and Aσp. No such correlation was found with toluene. The deactivation of the S1 state results from two oppositely acting factors: the intramolecular donoracceptor interaction and the intermolecular solute-solvent interaction

Acetylene chemisorption at palladium: Effect of temperature and structure of the surface

1984 ◽  
Vol 49 (6) ◽  
pp. 1448-1458
Author(s):  
Josef Kopešťanský
Keyword(s):  
Work Function ◽  
Atomic Hydrogen ◽  
Effect Of Temperature ◽  
Thermally Stable ◽  
Template Effect ◽  
Temperature Range ◽  
Adsorbed Layers ◽  
Different Types ◽  
Adsorption Complexes ◽  
Low Coverage

The effect of temperature and structure of the palladium surfaces on acetylene chemisorption was studied along with the interaction of the adsorbed layers with molecular and atomic hydrogen. The work function changes were measured and combined with the volumetric measurements and analysis of the products. At temperature below 100 °C, acetylene is adsorbed almost without dissociation and forms at least two different types of thermally stable adsorption complexes. Acetylene adsorbed at 200 °C is partly decomposed, especially in the low coverage region. Besides the above mentioned effects, the template effect of adsorbed acetylene was studied in the temperature range from -80° to 25 °C. It has been shown that this effect is a typical phenomenon of the palladium-acetylene system which is not due to surface impurities.

Specific features of the temperature dependence of tryptophan fluorescence lifetime in the temperature range of −170–20 °C

2020 ◽  
Vol 393 ◽  
pp. 112435
Author(s):  
Peter P. Knox ◽  
Vladimir V. Gorokhov ◽  
Boris N. Korvatovsky ◽  
Nadezhda P. Grishanova ◽  
Sergey N. Goryachev ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Fluorescence Lifetime ◽  
Tryptophan Fluorescence ◽  
Temperature Range

Highly boron-selective adsorbent by radiation induced grafting of N-vinylformamide on polyethylene/polypropylene sheet followed by hydrolysis and glycidol treatment

2021 ◽  
Vol 182 ◽  
pp. 109362
Author(s):  
Haruna Kolawole Afolabi ◽  
Mohamed Mahmoud Nasef ◽  
Nik Abdul Hadi Sapiaa ◽  
Noorfidza Yub Harun ◽  
Teo Ming Ting ◽  
...  
Keyword(s):  
Polypropylene Sheet ◽  
Radiation Induced ◽  
Selective Adsorbent ◽  
Radiation Induced Grafting

scholarly journals Temperature Dependence of Limiting Fluorescence Anisotropy of POPOP in Cellulose Acetate Film

1985 ◽  
Vol 40 (6) ◽  
pp. 559-561
Author(s):  
A. Kawski ◽  
A. Kubicki ◽  
I. Weyna ◽  
I. Janić
Keyword(s):  
Temperature Dependence ◽  
Cellulose Acetate ◽  
Fluorescence Anisotropy ◽  
Thermal Relaxation ◽  
Effect Of Temperature ◽  
Torsional Vibrations ◽  
Slow Increase ◽  
Cellulose Acetate Film ◽  
Luminescent Centre

The effect of temperature (103 K < T < 303 K) upon the limiting fluorescence anisotropy r0 of POPOP was investigated in a cellulose acetate film. A slow increase in r0 was observed when reducing the temperature. Based on the Jabłoński theory, the frequency of the torsional vibrations of POPOP was determined to be w = 1.3 x 1012s−1. The depolarization due to these torsional vibrations was found to occur immediately following excitation during the thermal relaxation of the luminescent centre, thus somewhat lowering the value of the fundamental fluorescence anisotropy rf to the limiting r0 value.

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