Electrical conductance and thermal behaviour of some manganese(II) carboxylates

1979 ◽  
Vol 57 (2) ◽  
pp. 151-156 ◽  
Author(s):  
Samuel Oluyemi Adeosun
Keyword(s):  
Specific Conductivity ◽  
Electrical Conductance ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Inverse Temperature ◽  
Isotropic Liquid ◽  
Dissociation Equilibrium ◽  
Electrical Conductances ◽  
High Degree ◽  
Simple Dissociation

Data are presented on the heats of phase transitions and electrical conductances of the even chain length manganese(II) carboxylates from octanoate to octadecanoate inclusive. The total entropy change for the transition crystal → isotropic liquid is small indicating a high degree of aggregation in the isotropic liquid. This behaviour is similar to that of the cadmium carboxylates.Plots of log specific conductivity against inverse temperature show curvature. Attempts to fit the data to the Vogel–Tammann–Fulcher equation[Formula: see text]showed non-random deviations. Instead, the data were interpreted in terms of a simple dissociation equilibrium for which the enthalpy change is ∼240 kJ mol−1.

scholarly journals Thermodynamics of ligand binding by the yeast mRNA-capping enzyme reveals different modes of binding

2004 ◽  
Vol 384 (2) ◽  
pp. 411-420 ◽  
Author(s):  
Isabelle BOUGIE ◽  
Amélie PARENT ◽  
Martin BISAILLON
Keyword(s):  
Ligand Binding ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Mrna Capping ◽  
Capping Enzyme ◽  
Eukaryotic Mrnas ◽  
Entropic Effect ◽  
A Minor ◽  
Rna Capping ◽  
Capping Enzymes

RNA-capping enzymes are involved in the synthesis of the cap structure found at the 5′-end of eukaryotic mRNAs. The present study reports a detailed study on the thermodynamic parameters involved in the interaction of an RNA-capping enzyme with its ligands. Analysis of the interaction of the Saccharomyces cerevisiae RNA-capping enzyme (Ceg1) with GTP, RNA and manganese ions revealed significant differences between the binding forces that drive the interaction of the enzyme with its RNA and GTP substrates. Our thermodynamic analyses indicate that the initial association of GTP with the Ceg1 protein is driven by a favourable enthalpy change (ΔH=−80.9 kJ/mol), but is also clearly associated with an unfavourable entropy change (TΔS=−62.9 kJ/mol). However, the interaction between Ceg1 and RNA revealed a completely different mode of binding, where binding to RNA is clearly dominated by a favourable entropic effect (TΔS=20.5 kJ/mol), with a minor contribution from a favourable enthalpy change (ΔH=−5.3 kJ/mol). Fluorescence spectroscopy also allowed us to evaluate the initial binding of GTP to such an enzyme, thereby separating the GTP binding step from the concomitant metal-dependent hydrolysis of GTP that results in the formation of a covalent GMP–protein intermediate. In addition to the determination of the energetics of ligand binding, our study leads to a better understanding of the molecular basis of substrate recognition by RNA-capping enzymes.

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.

STUDIES ON THE THERMODYNAMICS AND CONDUCTANCES OF MOLTEN SALTS AND THEIR MIXTURES: PART IV. THE ELECTRICAL CONDUCTANCES OF MOLTEN LITHIUM CHLORATE AND OF ITS MIXTURES WITH PROPYL ALCOHOL, LITHIUM NITRATE, WATER, METHYL ALCOHOL, AND LITHIUM HYDROXIDE

1964 ◽  
Vol 42 (8) ◽  
pp. 1984-1995 ◽  
Author(s):  
A. N. Campbell ◽  
D. F. Williams
Keyword(s):  
Activation Energy ◽  
Melting Point ◽  
Methyl Alcohol ◽  
Molten Salts ◽  
Electrical Conductance ◽  
Lithium Hydroxide ◽  
Lithium Nitrate ◽  
Propyl Alcohol ◽  
Electrical Conductances ◽  
Molten Lithium

The electrical conductance and its temperature dependence of molten lithium chlorate have been determined. Similar results have been obtained for lithium chlorate melts containing small quantities of methyl alcohol, propyl alcohol, lithium nitrate, lithium hydroxide, and water.The results obtained, taken in conjunction with the results of previous work, all indicate that the melt is complex. There is probably considerable association and this is especially evident slightly above the melting point: at temperatures in this region the temperature change of the properties of the lithium chlorate melt is greatest.The activation energy of conductance is approximately the same as the activation energy of viscous flow, for pure lithium chlorate melt and for mixtures of lithium chlorate with lithium nitrate. From this it appears that the melt constituents are not principally the simple ions, but that some form of cohesion exists between the simple constituents of the melt.The addition of water to the lithium chlorate melt causes the melt properties to alter considerably, especially the transport properties, viscosity and conductance. It is suggested that these changes may in part be due to a breakup of the structural entities of the pure melt, though the increase in electrical conductance cannot be completely explained in this way. A cryoscopic investigation seems to indicate that water is •not present as such in the melt.

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.

H/D Isotope Effects in the Conductivity of Licl Aqueous Solutions in Sub and Supercritical State

2003 ◽  
Vol 2003 (1) ◽  
pp. 4-5
Author(s):  
Ibrahim M. Ismail ◽  
Massao Numora ◽  
Yoshio Masuko ◽  
Hiroshi Tomiyasu ◽  
Yasuhiko Fujii
Keyword(s):  
Aqueous Solutions ◽  
Isotope Effects ◽  
Electrical Conductance ◽  
Supercritical State ◽  
Temperature Range ◽  
Flow Type ◽  
Electrical Conductances

The electrical conductances of LiCl in H2O and D2O solutions were measured in the temperature range 373 - 673 K at pressures up to 37.27 MPa, using a flow type electrical conductance cell.

scholarly journals Fluorescence study on the interaction of human serum albumin with loureirin B

2010 ◽  
Vol 24 (5) ◽  
pp. 547-557 ◽  
Author(s):  
Xu Chen ◽  
Jia-Ming Ma ◽  
Ke-Lan Yong ◽  
Jing-Ci Lv ◽  
Xia-Bing Zhang
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Fluorescence Spectra ◽  
Three Dimensional ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Dynamic Quenching ◽  
Fluorescence Study ◽  
Loureirin B

The interaction between loureirin B (Lour B) and human serum albumin (HSA) was investigated by fluorescence and UV–vis absorption spectroscopy. Experimental results indicated that loureirin B had a strong ability to quench the intrinsic fluorescence of HSA through a dynamic quenching procedure. The fluorescence quenching data revealed that the quenching constants (KSV) 2.68×104, 3.30×104and 4.10×104l/mol at 300, 310 and 320 K, respectively. Based on the thermodynamic parameters obtained, the positive values of enthalpy change ΔH and entropy change ΔS suggested that hydrophobic forces played a major role in the interaction of Lour B with HSA. According to Förster theory of energy transfer, the distancerbetween HSA and Lour B was calculated to be 2.85 nm. Furthermore, the effect of Lour B on the conformation of HSA was analyzed by synchronous fluorescence and three-dimensional fluorescence spectra.

scholarly journals Comparative termodynamic analysis of thrombin interaction with anti-thrombin aptamers and their heterodimeric construct

2010 ◽  
Vol 56 (3) ◽  
pp. 404-411 ◽  
Author(s):  
S.Yu. Rakhmetova ◽  
S.P. Radko ◽  
O.V. Gnedenko ◽  
N.V. Bodoev ◽  
A.S. Ivanov ◽  
...  
Keyword(s):  
Complex Formation ◽  
Temperature Interval ◽  
Entropy Change ◽  
Optical Biosensor ◽  
Dissociation Rate ◽  
Enthalpy Change ◽  
Anion Binding ◽  
Kd Values ◽  
Formation Of Complexes

Aptamers interacting selectively with the anion-binding exosites 1 and 2 of thrombin were merged into dimeric oligonucleotide constructs with use of a poly-(dT)-linker of 35 nucleotides (nt) long. Complexes of thrombin with the aptamers and their hetero- and homodimeric constructs were measured using the optical biosensor Biacore-3000. KD values measured for the hetero- and homodimeric constructs were correspondingly 25-30- and 2-3-fold lower than those for the primary aptamers. Analysis of temperature dependencies of KD values within the temperature interval of 10°C-40°C has shown that the values of enthalpy change ΔH upon formation of complexes of thrombin with the aptamers and the hetrodimeric construct are close. The value of the entropy change ΔS upon complex formation of thrombin with the aptamer heterodimeric construct was 1.5-2-fold higher than ΔS values for the complexes with the aptamers. The complex formation and dissociation rates increased with the elevation of temperature from 10°С to 37°С. However, the dissociation rate for the complex of thrombin with the heterodimeric construct was evidently lower that that for the complexes with the aptamers.

Removal of Malachite Green from Aqueous Solutions by Perlite

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Vijayakumar Govindasamy ◽  
Renganathan Sahadevan ◽  
Sivanesan Subramanian ◽  
Dharmendira Kumar Mahendradas
Keyword(s):  
Malachite Green ◽  
Contact Time ◽  
Adsorption Process ◽  
Dye Adsorption ◽  
Freundlich Isotherm ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Order Kinetic ◽  
Batch Mode ◽  
Adsorption Mechanisms

Perlite was utilized as an adsorbent for the removal of malachite green from their aqueous solution. The effects of the initial dye concentration, contact time, adsorbent dose, pH, and temperature were studied for the adsorption of malachite green in batch mode. The dye adsorption equilibrium was rapidly attained after 40 min of contact time. Adsorbent was characterized by FTIR, XRD and SEM. The Langmuir and Freundlich isotherm described the adsorption data over the concentration range (20 – 100 mg/L). The rate parameters of the intra particle diffusion were calculated and compared to identify the adsorption mechanisms. The thermodynamic parameters such as entropy change, enthalpy change, and energy of adsorption were calculated to know the nature of adsorption. The negative values of energy of adsorption and the positive values of enthalpy change suggested that the adsorption process is spontaneous and exothermic. Kinetic studies showed that the adsorption process obeyed the pseudo first-order kinetic model.

Thermal Transformation in Anhydrous Rare Earth Acetates

1972 ◽  
Vol 50 (19) ◽  
pp. 3100-3103 ◽  
Author(s):  
G. Adachi ◽  
E. A. Secco
Keyword(s):  
Thermal Analysis ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Ionic Radius ◽  
Thermal Transformation ◽  
Entropy Change ◽  
Transformation Process ◽  
Enthalpy Change ◽  
Transformation Property ◽  
The Rare Earth

The thermal transformation in anhydrous acetates of Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y has been studied by thermal analysis. The enthalpy change, ΔH, and the entropy change, ΔS, accompanying the transformation process are reported and related to ionic radius of the rare earth element.The acetates of the rare earth elements, La, Pr, and Nd did not exhibit the thermal transformation property.

scholarly journals Thermodynamics of electrochemical reactions in Lead-acid Battery

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Adebayo Akinbulu ◽  
Toafeek Ogunbayo
Keyword(s):  
Free Energy ◽  
Temperature Coefficient ◽  
Electromotive Force ◽  
Electrochemical Reaction ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Electrochemical Reactions ◽  
Positive Entropy ◽  
Lead Acid Battery ◽  
Lead Acid

Thermodynamics of the electrochemical reaction in lead-acid battery was investigated. A negative value of change in Gibbs’ free energy, ?G, and a positive entropy change, ?S, were obtained for the reaction. ?G was more negative at increased temperature. The reaction was exothermic, with a negative value of enthalpy change, ?H. A relatively small value of temperature coefficient of the electromotive force of the cell, (?E/?T)_P, was also obtained for the reaction.

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