Exploring ion induced folding of a single-stranded DNA oligomer from molecular simulation studies

2016 ◽  
Vol 18 (23) ◽  
pp. 15899-15910 ◽  
Author(s):  
Kaushik Chakraborty ◽  
Prabir Khatua ◽  
Sanjoy Bandyopadhyay
Keyword(s):  
Free Energy ◽  
Molecular Simulation ◽  
Close Contact ◽  
Free Energy Change ◽  
Energy Change ◽  
Simulation Studies ◽  
Single Stranded Dna ◽  
Induced Folding ◽  
Sphere Complex ◽  
Dna Strand

Formation of Na+ ion-induced inner-sphere complex folds the DNA strand by bringing two non-sequential residues in close contact with a net free energy change of −4.1 kcal mol−1.

Modeling of Electrical Resistivity Evolution Using Free Energy Analysis for NiTi Shape Memory Alloy Wires

2011 ◽  
Vol 311-313 ◽  
pp. 2282-2285
Author(s):  
Jian Jun Zhang
Keyword(s):  
Electrical Resistivity ◽  
Free Energy ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Free Energy Change ◽  
Energy Change ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Proposed Model ◽  
Free Energy Analysis

This paper presents a transformation kinetics model of NiTi shape memory alloy (SMA) wires based on electrical resistivity (ER) derivative study under the assumption that the derivative of electrical resistivity with respect to temperature is in linear relationship with the derivative of free energy change with respect to temperature. Free energy change and electrical resistivity properties of SMA are analyzed based on differential scanning calorimetry (DSC) experiments during phase transformation. The simulated evolution of electrical resistivity during thermomechanical transformation is presented using the proposed model.

Adsorption of Liquids and Swelling of Wood. Part VI. Saturated Amounts and Some Thermodynamic Values of Adsorption

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 91-97
Author(s):  
Kei Morisato ◽  
Yutaka Ishimaru ◽  
Hiroyuki Urakami
Keyword(s):  
Free Energy ◽  
Standard Free Energy ◽  
Molecular Size ◽  
Free Energy Change ◽  
Energy Change ◽  
Multilayer Adsorption ◽  
Monolayer Adsorption ◽  
Wood Part ◽  
Cohesive Interaction

Summary To understand the swelling phenomenon of wood in liquids,the saturated amount of adsorption of liquids onto wood and the standard free energy changes of the adsorption were determined. The saturated amount of adsorption obtained by regression for several liquids decreased with increasing molecular size of the solvents. The mechanism of wood swelling is discussed systematically taking all the liquids examined in previous experiments into account. Since methanol molecules require more energy for release from cohesive interactions within bulk liquids in the adsorption onto pre-swollen wood,the values of free energy change of adsorption for methanol were lower than the values for acetone,although the relative swelling with methanol was higher. These results suggest that although the cohesive interaction within the bulk liquids reduces adsorptivity,the phenomenon of wood swelling is influenced not only by monolayer adsorption but also by multilayer adsorption. Therefore,the cohesive interaction within the bulk liquids reduces adsorptivity but enhances the condensation which strongly influences the swelling of wood.

scholarly journals REMOVAL OF CU (II) FROM DYE EFFLUENT USING NATURAL AND PHOSPHATE-MODIFIED NIGERIAN KAOLINITE CLAY

2019 ◽  
Vol 7 (8) ◽  
pp. 402-414
Author(s):  
S. C. Olu ◽  
P. E. Dim ◽  
J. O. Okafor
Keyword(s):  
Free Energy ◽  
Metal Ion ◽  
Fourier Transforms ◽  
Lattice Structure ◽  
Enthalpy Change ◽  
Free Energy Change ◽  
Energy Change ◽  
Order Model ◽  
Acid Modification ◽  
Kaolinite Clay

This study indicates kaolinite clay as an effective adsorbent for the uptake of Cu (II) from wastewater. The adsorption process was studied with variation of time, temperature and adsorbent dosage at the effluent pH of 6. X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), Brunauer Emmett and Teller (BET) and Scanning electron microscopy (SEM) were used to characterize the adsorbents. XRD spectra showed that modification with KH2PO4 did not significantly change the crystal spacing on the lattice structure of the clay mineral; however, there were shifts in the intensity of the peaks for the modified kaolinite clay. The FTIR spectra showed that certain functional groups are responsible for binding the metal ions from solution. SEM indicated an increase in the porosity of the modified adsorbent as compared with the unmodified kaolinite, which enhances metal ion adsorption on modified kaolinite clay. The BET indicate that acid modification increased the surface area and total pore volume of the kaolinite clay. The kinetic study revealed that the pseudo-first-order model fitted poorly to the equilibrium data, however, the pseudo-second-order model had a good fit for all reaction time at different initial concentrations. The mechanism of the sorption process was evaluated using thermodynamic properties such as enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS), which were evaluated using Van’t Hoff equations. The negative values of free energy change (ΔG), suggests spontaneity and feasibility of the process. The positive values of enthalpy change (ΔH) indicate endothermic nature of the process.

scholarly journals Kinetic and Thermodynamic Studies of Lysozyme Adsorption on Cibacron Blue F3GA Dye-Ligand Immobilized on Aminated Nanofiber Membrane

Membranes ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 963
Author(s):  
Ai Hsin ◽  
Su-Chun How ◽  
Steven S.-S. Wang ◽  
Chien Wei Ooi ◽  
Chen-Yaw Chiu ◽  
...  
Keyword(s):  
Free Energy ◽  
Free Energy Change ◽  
Energy Change ◽  
Nanofiber Membrane ◽  
Cibacron Blue ◽  
Pseudo Second Order ◽  
Nanofiber Membranes ◽  
Lysozyme Adsorption ◽  
Cibacron Blue F3ga ◽  
Pan Nanofiber

The polyacrylonitrile (PAN) nanofiber membrane was prepared by the electrospinning technique. The nitrile group on the PAN nanofiber surface was oxidized to carboxyl group by alkaline hydrolysis. The carboxylic group on the membrane surface was then converted to dye affinity membrane through reaction with ethylenediamine (EDA) and Cibacron Blue F3GA, sequentially. The adsorption characteristics of lysozyme onto the dye ligand affinity nanofiber membrane (namely P-EDA-Dye) were investigated under various conditions (e.g., adsorption pH, EDA coupling concentration, lysozyme concentration, ionic strength, and temperature). Optimum experimental parameters were determined to be pH 7.5, a coupling concentration of EDA 40 μmol/mL, and an immobilization density of dye 267.19 mg/g membrane. To understand the mechanism of adsorption and possible rate controlling steps, a pseudo first-order, a pseudo second-order, and the Elovich models were first used to describe the experimental kinetic data. Equilibrium isotherms for the adsorption of lysozyme onto P-EDA-Dye nanofiber membrane were determined experimentally in this work. Our kinetic analysis on the adsorption of lysozyme onto P-EDA-Dye nanofiber membranes revealed that the pseudo second-order rate equation was favorable. The experimental data were satisfactorily fitted by the Langmuir isotherm model, and the thermodynamic parameters including the free energy change, enthalpy change, and entropy change of adsorption were also determined accordingly. Our results indicated that the free energy change had a negative value, suggesting that the adsorption process occurred spontaneously. Moreover, after five cycles of reuse, P-EDA-Dye nanofiber membranes still showed promising efficiency of lysozyme adsorption.

Theoretical Thermodynamic Analysis and Phase Analysis of AZ91D/Flyash Composites

2014 ◽  
Vol 788 ◽  
pp. 604-607
Author(s):  
Hong Chao Chu ◽  
Si Rong Yu ◽  
Cui Xiang Wang ◽  
Qi Lou
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Minimum Principle ◽  
Solution Treatment ◽  
Entropy Change ◽  
Treatment Temperature ◽  
Free Energy Change ◽  
Energy Change ◽  
Solution Treatment Temperature ◽  
Gibbs Free Energy Change

The thermodynamic calculation is valuable for judging the feasibility of a reaction. In the present paper, the enthalpy change (∆HR), entropy change (∆SR) and Gibbs free energy change (∆GR) among various components in AZ91D Mg alloy-Cenosphere composites (FAC/AZ91D) were calculated. Through the calculation, we obtained the relationships between the Gibbs free energy changes and temperatures. The difficulty degree of every potential reaction could be directly reflected by the correlation curve between the temperature and the Gibbs free energy change. The analysis result provided the theoretical basis for the reaction temperature and the solution treatment temperature of the FAC/AZ91D system. At the same time, the analysis based on the minimum principle of the reaction free energy revealed the final components (MgO, Mg2Si and MgAl2O4), which was partially similar to the result of XRD analysis (MgO, Mg2Si and Mg17Al12).

scholarly journals Using Intrinsic Surfaces To Calculate the Free-Energy Change When Nanoparticles Adsorb on Membranes

2018 ◽  
Vol 122 (24) ◽  
pp. 6417-6422 ◽  
Author(s):  
Joaquín Klug ◽  
Carles Triguero ◽  
Mario G. Del Pópolo ◽  
Gareth A. Tribello
Keyword(s):  
Free Energy ◽  
Free Energy Change ◽  
Energy Change
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