scholarly journals A method for investigating the effect of temperature on the 695 nm band of insoluble cytochrome c

1975 ◽  
Vol 149 (1) ◽  
pp. 169-177 ◽  
Author(s):  
T A Moore ◽  
C Greenwood
Keyword(s):  
Ionic Strength ◽  
Cytochrome C ◽  
Computer Analysis ◽  
Standard Enthalpy ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Effect Of Temperature ◽  
Standard Entropy ◽  
Ferricytochrome C ◽  
Standard Enthalpy Change

A method is described for computer analysis of simple spectrophotometric changes in particulate systems, and this has been applied to the bleaching of the 695 nm band of insoluble ferricytochrome c by temperature. The results show that insolubilization has no effect on the standard enthalpy change but lowers the value for the standard entropy change. This effect appears to be independent of the concentration of the gel matrix to which the cytochrome c is bound, but dependent on the ionic strength of the surrounding solution.

The Equilibrium and the Determination of D00 (H—CN)

1975 ◽  
Vol 53 (16) ◽  
pp. 2365-2370 ◽  
Author(s):  
Don Betowski ◽  
Gervase Mackay ◽  
John Payzant ◽  
Diethard Bohme
Keyword(s):  
Free Energy ◽  
Standard Enthalpy ◽  
Transfer Reaction ◽  
Standard Free Energy ◽  
Proton Transfer Reaction ◽  
Enthalpy Change ◽  
Standard Free Energy Change ◽  
Flowing Afterglow ◽  
Standard Enthalpy Change

The rate constants and equilibrium constant for the proton transfer reaction [Formula: see text] have been measured at 296 ± 2 K using the flowing afterglow technique: kforward = (2.9 ± 0.6) × 10−9 cm3molecule−1s−1, kreverse = (1.8 ± 0.4) × 10−10 cm3 molecule1 s−1, and K = 16 ± 2. The measured value of K corresponds to a standard free energy change, ΔG296°, of −1.6 ± 0.1 kcal mol−1 which provides values for the standard enthalpy change, ΔH298°= −1.0 ± 0.2 kcal mol−1, the bond dissociation energy, D00(H—CN) = 124 ± 2 kcal mol−1, and the proton affinity, p.a.(CN−) = 350 ± 1 kcal mol−1.

scholarly journals Spectroscopic investigation of the interaction of bovine serum albumin with a novel cardiac agent V-09

2008 ◽  
Vol 22 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Changyun Chen ◽  
Meihua Ma ◽  
Junqi Zhang ◽  
Lichen Wang ◽  
Bingren Xiang
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Average Distance ◽  
Cardiac Activity ◽  
Binding Constants ◽  
Entropy Change ◽  
Standard Entropy ◽  
Förster Energy Transfer ◽  
Standard Enthalpy Change

This study employs fluorescence spectroscopy to characterize the binding properties of a newly synthesized cardiac agent, V-09, on bovine serum albumin (BSA). This compound shows the highest cardiac activity in the whole series. The binding constantsKat 25°C and 37°C are obtained, the values are 7.12×104l mol–1, 4.66×104l mol–1, respectively. The standard enthalpy change (ΔH0) and the standard entropy change (ΔS0) are calculated to be –27.13 KJ mol–1and 1.854 J mol–1K–1, which indicated that hydrophobic forces play major role in the interaction between V-09 and BSA. The binding average distance between V-09 and BSA (2.57 nm) is obtained on the basis of the theory of Főrster energy transfer.

scholarly journals Temperature effect on ion exchange equilibrium between CMX membrane and electrolytes solutions

2015 ◽  
Vol 5 (4) ◽  
pp. 535-541 ◽  
Author(s):  
Akrem Chaabouni ◽  
Fatma Guesmi ◽  
Islem Louati ◽  
Chiraz Hannachi ◽  
Béchir Hamrouni
Keyword(s):  
Ion Exchange ◽  
Binary Systems ◽  
Equilibrium Constants ◽  
Exchange Process ◽  
Standard Free Energy ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Exchange Equilibrium ◽  
Standard Entropy ◽  
Ion Exchange Process

Ion exchange equilibrium for three systems involving monovalent and divalent ions has been investigated over various temperatures (283, 298 and 313 K) using CMX cationic exchange membrane. All experiments were carried out at 0.1 mol/L. Ion exchange isotherms for the binary systems (Na+/K+), (Na+/Ca2+) and (K+/Ca2+) were established at temperatures ranging from 283 to 313 K. The obtained affinity order is: K+>Ca2+>Na+. Selectivity coefficients KK+2Na+, K2Na+Ca2+ and KCa2+2K+ were determined and found to increase with rise in temperature. Thermodynamic equilibrium constants Ki°j were calculated. Wilson and Debye–Hückel equations have been used to calculate activity coefficients in the membrane and solution, respectively. Standard free energy ΔGT°, standard enthalpy change ΔHT° and standard entropy change ΔST° were calculated. The values of ΔHT° were found to be 51.98 kJ/mol, 64.59 kJ/mol and 29.57 kJ/mol, respectively, for (Na+/K+), (Na+/Ca2+) and (K+/Ca2+) binary systems, which indicate that the ion exchange process between the CMX membrane and the studied binary systems is an endothermic process. ΔST° is found to be positive, which means that the increased randomness appeared on the membrane-solution interface during the ion exchange reaction. In addition, the standard free enthalpy change ΔGT° value for all systems is negative, which is an indication that the ion exchange equilibrium is spontaneous in standard conditions.

Adsorption of Liquids and Swelling of Wood IV. Temperature Dependence on the Adsorption

Holzforschung ◽  
1999 ◽  
Vol 53 (6) ◽  
pp. 669-674 ◽  
Author(s):  
Kei Morisato ◽  
Hitoshi Kotani ◽  
Yutaka Ishimaru ◽  
Hiroyuki Urakami
Keyword(s):  
Free Energy ◽  
Temperature Dependence ◽  
Standard Enthalpy ◽  
Cell Walls ◽  
Standard Free Energy ◽  
Isosteric Heat ◽  
Enthalpy Change ◽  
Standard Free Energy Change ◽  
Standard Enthalpy Change ◽  
Low Activity

Summary For the purpose of understanding the swelling phenomenon of wood in liquids, the contributions of enthalpic and entropic terms to the standard free energy change of adsorption have been determined by measuring the temperature dependence of adsorption isotherms. The values of standard enthalpy change of adsorption are smaller for alcohols having both proton-accepting and -donating properties than for acetone having only a proton-accepting property. The results are discussed in terms of the proton-accepting power and the cohesive energy of the respective adsorbate liquids. Methanol showed a larger isosteric heat of adsorption to dried wood than to pre-swollen wood, and the amounts of methanol and acetone adsorbed on dried wood exceeded those on swollen wood within the low activity range. These results indicate the presence of more exothermic sites in dried wood than in pre-swollen wood, and of pre-existing spaces and/or parts loosely hydrogen-bonded between wood constituents in the cell walls of dried wood.

Synthesis of kaolinite/iron oxide magnetic composites and their use in the removal of Cd(II) from aqueous solutions

2013 ◽  
Vol 67 (7) ◽  
pp. 1642-1649 ◽  
Author(s):  
Pengfei Zong ◽  
Shoufang Wang ◽  
Chaohui He
Keyword(s):  
Iron Oxide ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Sorption Capacity ◽  
Sorption Isotherms ◽  
Entropy Change ◽  
Solution Chemistry ◽  
Standard Entropy ◽  
Iron Oxide Particles ◽  
Magnetic Composites

Kaolinite/iron oxide magnetic composites (kaolinite/MCs) were used as adsorbent for the removal of Cd(II) from aqueous solutions. The influences of pH, ionic strength, solid/liquid ratio and temperature on Cd(II) sorption on kaolinite/MCs were evaluated. The results showed that the removal of Cd(II) on kaolinite/MCs was strongly dependent on pH and ionic strength. An optimal kaolinite/MCs concentration mass per volume for removal of Cd(II) from aqueous solutions was 1.4 g L–1. The Langmuir and Freundlich models were used to simulate sorption isotherms of Cd(II) at three different temperatures of 293, 313 and 333 K. The sorption of Cd(II) on kaolinite/MCs increased with increasing temperature, and thermodynamic parameters (standard entropy change, enthalpy change and Gibbs free energy change) illustrated that this sorption process was spontaneous and endothermic. The sorption behaviors of Cd(II) were mainly dependent on surface properties of kaolinite/MCs and solution chemistry conditions. The sorption capacity of Cd(II) on kaolinite/MCs was lower than that on kaolinite, because iron oxide particles decreased surface charge of kaolinite leading to less sorption capacity. Due to high magnetism, kaolinite/MCs could be easily separated with an external magnetic field. Kaolinite/MCs could therefore be used as potential adsorbent for preconcentration and immobilization of Cd(II) ions from large volumes of aqueous solutions.

scholarly journals Kinetics and Thermodynamics of the Adsorption of Lead (II) on a Activated Carbon from Coconut Shells

2013 ◽  
Vol 15 (4) ◽  
pp. 283 ◽  
Author(s):  
L. Largitte ◽  
P. Lodewyckx
Keyword(s):  
Activated Carbon ◽  
Standard Enthalpy ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Activation Parameters ◽  
Effect Of Temperature ◽  
Standard Entropy ◽  
Exponential Factor ◽  
Different Temperatures ◽  
Coconut Shells

The effect of temperature on the adsorption of lead by an activated carbon from coconut shells is investigated. The pseudo second order equation is applied to the kinetic data obtained at different temperatures in order to determine the adsorption rate constants at these temperatures. Then, the Arrhenius equation is applied to the rate constants to determine the activation energy of the sorption reaction and the pre-exponential factor. By applying the Eyring equation to the rate constants, the standard thermodynamic activation parameters of the sorption reaction can also be calculated. In addition, the isotherms of lead adsorption on the activated carbon from coconut shells, at different temperatures, are determined and fitted by the Langmuir equation. The Van’t Hoff equation is applied to the Langmuir equilibrium constants in order to determine the standard enthalpy of the sorption reaction. The other standard thermodynamic parameters<br />(Gibbs standard enthalpy and standard entropy) are deduced. The isosteric standard sorption enthalpy is also determined by using both the classical approach and an adapted Clausius Clapeyron equation. The results are identical. The value obtained is higher, but more correct than that of Langmuir. On the basis of these<br />thermokinetic parameters, the activated carbon from Coconut shells can be considered as a very efficient carbon for the sorption of lead and its sorption efficiency (rate and quantity) increase with the temperature.

Cytochrome c reduction by cysteine plus copper: a pseudosubstrate system for cytochrome c oxidase

1980 ◽  
Vol 58 (6) ◽  
pp. 499-503 ◽  
Author(s):  
Bruce C. Hill ◽  
Peter Nicholls
Keyword(s):  
Electron Transfer ◽  
Ionic Strength ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxygen Electrode ◽  
Horse Heart Cytochrome ◽  
Ferricytochrome C ◽  
Cytochrome C Reduction ◽  
Low Ionic Strength ◽  
Horse Heart Cytochrome C

Cysteine alone reduces horse heart cytochrome c very slowly [Formula: see text] with a rate constant virtually identical in high and low ionic strength buffers. Copper catalyzes this reaction increasing the rate by a factor of 105 in 50 mM phosphate and by a factor of 106 in 10 mM Tris buffers. When ferricytochrome c and cysteine are mixed in an oxygen electrode a "burst" of oxygen uptake is seen, the decline in which parallels the reduction of cytochrome c. When cytochrome c oxidase is added to such a mixture two routes of electron transfer to oxygen exist: enzymatic and ferricytochrome c dependent nonenzymatic. Both processes are sensitive to cyanide, but azide inhibits only the authentic cytochrome c oxidase catalyzed process and BCS the ferricytochrome c stimulated reaction.

Thermodynamic analyses of the orthorhombic-to-tetragonal phase transition in Pr2−xNdxNiO4+δ under controlled oxygen partial pressures

2020 ◽  
Vol 49 (34) ◽  
pp. 11931-11941
Author(s):  
Eiki Niwa ◽  
Tsubasa Sato ◽  
Takuya Hashimoto
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Tetragonal Phase ◽  
Structural Phase ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Standard Entropy ◽  
Partial Pressures ◽  
Tetragonal Phase Transition

The standard entropy change, ΔS°, and enthalpy change, ΔH°, at the structural phase transition of Pr2−xNdxNiO4+δ and their impact on variation of phase transition temperature by Nd content.

Evaluation of Unbonded O—H Groups for HDO in Liquid D2O from Infrared Absorptivity Measurements

1972 ◽  
Vol 50 (11) ◽  
pp. 1655-1665 ◽  
Author(s):  
E. C. W. Clarke ◽  
D. N. Glew
Keyword(s):  
Temperature Dependence ◽  
Equilibrium Constant ◽  
Standard Enthalpy ◽  
Liquid State ◽  
Low Temperatures ◽  
Enthalpy Change ◽  
Weak Band ◽  
Equilibrium Quotient ◽  
Standard Enthalpy Change

Wyss and Falk's infrared absorptivities between 10 and 85 °C for HDO in liquid D2O in the fundamental O—H stretch region have been analyzed numerically and show a statistically significant weak band near 3600 cm−1 at each temperature. This band, the Raman analog of which was reported earlier, confirms the presence of HDO species with unbonded O—H groups in the liquid state. The percentage of HDO species with un-bonded O—H groups is found to be 4.6, 6.1, 10.1, and 11.9, respectively, at 10, 35, 60, and 85 °C.The four predominant HDO species in equilibrium at low temperatures are denned together with their equilibrium constant for the [Formula: see text] bond-rupturing process. A standard enthalpy change of ΔH° = 6800 ± 1100 cal is found for the rupture of one mole of [Formula: see text] bonds. This is in contrast with the apparent enthalpy change of 2900 ± 500 cal, as usually derived from the temperature dependence of the equilibrium quotient. Approximate mole fractions for each of twelve differently bonded HDO species are derived from a model for random H- and D-bond statistics. Results show that the four predominant HDO species give a full interpretation of the absorptivities at 10, 35, and 60 °C but that additional minor species contribute slightly to the absorptivity at 85 °C.

scholarly journals Thermodynamic Study of Racemic Ibuprofen Separation by Liquid Chromatography Using Cellulose-Based Stationary Phase

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Wilson M. Ferrari ◽  
Ana C. Nascimento ◽  
Jean V. Moreira ◽  
Marco A. Cremasco
Keyword(s):  
Liquid Chromatography ◽  
Stationary Phase ◽  
Mobile Phase ◽  
Isopropyl Alcohol ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Effect Of Temperature ◽  
Racemic Form ◽  
Chiral Drug ◽  
Racemic Ibuprofen

Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID), also known for its significant antipyretic and analgesic properties. This chiral drug is commercialized in racemic form; however, only S-(+)-ibuprofen has clinical activities. In this paper the effect of temperature change (from 288.15 to 308.15 K) on the ibuprofen resolution was studied. A column (250×4.6 mm) packed with tris(3,5-dimethylphenylcarbamate) was used to obtain the thermodynamic parameters, such as enthalpy change (ΔH), entropy change (ΔS), variation enthalpy change (ΔΔH), variation entropy change (ΔΔS), and isoenantioselective temperature (Tiso). The mobile phase was a combination of hexane (99%), isopropyl alcohol (1%), and TFA (0.1%), as an additive. The conditions led to a selectivity of 1.20 and resolution of 4.55. The first peak, R-(−)-ibuprofen, presented an enthalpy change of 7.21 kJ/mol and entropy change of 42.88 kJ/K·mol; the last peak, S-(+)-ibuprofen, has an enthalpy change of 8.76 kJ/mol and 49.40 kJ/K·mol of entropy change.

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