Translational Entropy and Dispersion Energy Jointly Drive the Adsorption of Urea to Cellulose

2017 ◽  
Vol 121 (10) ◽  
pp. 2244-2251 ◽  
Author(s):  
Pan Chen ◽  
Yoshiharu Nishiyama ◽  
Jakob Wohlert ◽  
Ang Lu ◽  
Karim Mazeau ◽  
...  
Keyword(s):  
Dispersion Energy ◽  
Translational Entropy

On the change of the order od stability of DNA base pairs as a result of the methylation of guanine

1988 ◽  
Vol 53 (9) ◽  
pp. 1943-1945
Author(s):  
Pavel Hobza ◽  
Camille Sandorfy
Keyword(s):  
Ab Initio ◽  
Base Pairs ◽  
Dispersion Energy ◽  
Dna Base ◽  
Dna Base Pairs

The interaction of the 6-O methylguanine cation with cytosine and thymine was studied using the ab initio SCF method in combination with a London type expression for dispersion energy. The structure of the complex formed with cytosine differs from that found previously with guanine itself.

scholarly journals A Novel Index (RI) to Evaluate the Relative Stability of Soils Using Ultrasonic Agitation

2021 ◽  
Vol 13 (8) ◽  
pp. 4229
Author(s):  
Fakher Abbas ◽  
Fang Lin ◽  
Zhaolong Zhu ◽  
Shaoshan An
Keyword(s):  
Relative Stability ◽  
Characteristic Curve ◽  
Geometric Mean ◽  
Relative Strength ◽  
Soil Stability ◽  
Dispersion Energy ◽  
Ultrasonic Agitation ◽  
Mean Weight Diameter ◽  
Change In Mean ◽  
Wet Sieving

As soil stability is a complex phenomenon, various methods and indexes were introduced to assess the strength of soils. Because of the limitations of different stability methods and indexes (including wet sieving-based), we aimed to presents a relative stability index (RI) that was based on the estimated components of the soil overall disruptive characteristic curve (SODC): (1) soil disruption constant (Ki, that is based upon dispersion energy of soils); (2) resulting change in mean weight diameter (ΔMWD). To evaluate the effectiveness and limitations of RI as well as to compare it with classical soil stability indexes of mean weight diameter (MWD) and geometric mean diameter (GMD). Ultrasonic agitation (UA) along with a wet sieving method (followed by dry sieving) was applied against four different soils named on the basis of sample location, Qingling soil (QL), Guanzhong soil (GZ), Ansai soil (AS), and Jingbian soil (JB). To evaluate the relative strength of soils at different applied energies (increase in sonication duration usually resulted in increased input energy and temperature of soil–water suspension), soils were subjected to six sonication durations (0, 30, 60, 120, 210, and 300 s) with a fixed (and exact) initial amplitude and temperature. Output energy was calculated based on the amplitude and temperature of the suspension, vessel, and system. The most abrupt and maximum disruption of soil aggregates was observed at a dispersion energy level of 0–200 J g−1. The MWD value of surface and subsurface ranged between 0.58 to 0.15 mm and 0.37 to 0.17 mm, respectively, while GMD was ranged from 0.14 to 0.33 mm overall. The results for MWD and GMD showed a similar trend. MWD and GMD showed more strong associations with physicochemical characteristics of soil than RI. A non-significant correlation was found between RI and MWD/GMD. Contrary to MWD and GMD, RI was significantly positively correlated with sand content; this finding indicated the influential role of sand in assessing the soil’s relative strength. The results indicated that JB soil possessed the least MWD and GMD but proved to be relatively stable because of having the highest RI value.

scholarly journals Crystal Structure and Computational Study on Methyl-3-Aminothiophene-2-Carboxylate

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 19 ◽  
Author(s):  
Yaping Tao ◽  
Ligang Han ◽  
Andong Sun ◽  
Kexi Sun ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Crystal Packing ◽  
Computational Study ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Dispersion Energy ◽  
Monoclinic Crystal ◽  
Hydrogen Bond Interactions ◽  
Calculation Results ◽  
Reduced Density Gradient ◽  
Reduced Density

Methyl-3-aminothiophene-2-carboxylate (matc) is a key intermediate in organic synthesis, medicine, dyes, and pesticides. Single crystal X-ray diffraction analysis reveals that matc crystallizes in the monoclinic crystal system P21/c space group. Three matc molecules in the symmetric unit are crystallographically different and further linked through the N–H⋯O and N–H⋯N hydrogen bond interactions along with weak C–H⋯S and C–H⋯Cg interactions, which is verified by the three-dimensional Hirshfeld surface, two-dimensional fingerprint plot, and reduced density gradient (RDG) analysis. The interaction energies within crystal packing are visualized through dispersion, electrostatic, and total energies using three-dimensional energy-framework analyses. The dispersion energy dominates in crystal packing. To better understand the properties of matc, electrostatic potential (ESP) and frontier molecular orbitals (FMO) were also calculated and discussed. Experimental and calculation results suggested that amino and carboxyl groups can participate in various inter- and intra-interactions.

Efficient Approximation of Ligand Rotational and Translational Entropy Changes upon Binding for Use in MM-PBSA Calculations

2017 ◽  
Vol 57 (2) ◽  
pp. 170-189 ◽  
Author(s):  
Ido Y. Ben-Shalom ◽  
Stefania Pfeiffer-Marek ◽  
Karl-Heinz Baringhaus ◽  
Holger Gohlke
Keyword(s):  
Entropy Changes ◽  
Translational Entropy ◽  
Efficient Approximation

scholarly journals Characteristics of Poly(vinyl Alcohol) (PVA) Based Composites Integrated with Green Synthesized Al3+-Metal Complex: Structural, Optical, and Localized Density of State Analysis

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1316
Author(s):  
Shujahadeen B. Aziz ◽  
Muaffaq M. Nofal ◽  
Hewa O. Ghareeb ◽  
Elham M. A. Dannoun ◽  
Sarkawt A. Hussen ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Metal Complex ◽  
Band Gap ◽  
Optical Band Gap ◽  
Complex Dielectric Constant ◽  
Poly Vinyl Alcohol ◽  
Optical Parameters ◽  
Dispersion Energy ◽  
Casting Technique

The influence of dispersing Al-metal complex on the optical properties of PVA was investigated using UV–visible spectroscopy. Polymer composite films with various Al3+-complex amounts in the PVA matrix were arranged by solution casting technique by means of distilled water as a widespread solvent. The formation of Al3+-metal complex was verified through Ultraviolet–visible (UV-Vis) and Fourier-transform infrared spectroscopy (FTIR) examinations. The addition of Al-complex into the polymer matrix led to the recovery of the optical parameters such as dielectric constant (εr and εi) and refractive index (n). The variations of real and imaginary parts of complex dielectric constant as a function of photon wavelength were studied to calculate localized charge density values (N/m*), high-frequency dielectric constant, relaxation time, optical mobility, optical resistivity, and plasma angular frequency (ωp) of electrons. In proportion with Al3+-complex content, the N/m* values were amplified from 3.68 × 1055 kg−1 m−3 to 109 × 1055 kg−1 m−3. The study of optical parameters may find applications within optical instrument manufacturing. The optical band gap was determined from Tauc’s equation, and the type of electronic transition was specified. A remarkable drop in the optical band gap was observed. The dispersion of static refractive index (no) of the prepared composites was analyzed using the theoretical Wemple–DiDomenico single oscillator model. The average oscillator energy (Eo) and oscillator dispersion energy (Ed) parameters were estimated.

scholarly journals An analysis of the partial wave expansion of the dispersion energy for Ne2

1984 ◽  
Vol 110 (4) ◽  
pp. 369-374 ◽  
Author(s):  
G. Chałasiński ◽  
J.H. van Lenthe ◽  
Th.P. Groen
Keyword(s):  
Partial Wave ◽  
Dispersion Energy ◽  
Partial Wave Expansion ◽  
Wave Expansion

Effect of non-annealed and annealed ZnO on the optical properties of PVC/ZnO nanocomposite films

2021 ◽  
pp. 089270572110386
Author(s):  
Ali F Al-Shawabkeh ◽  
Ziad M Elimat ◽  
Khaleel N Abushgair
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Zno Nanoparticles ◽  
Oscillator Strengths ◽  
Nanocomposite Films ◽  
Optical Parameters ◽  
Zno Nanoparticle ◽  
Dispersion Energy ◽  
Optical Susceptibility

The goal of this study was to investigate the optical properties of the prepared polyvinyl chloride (PVC)/zinc oxide (ZnO) nanocomposite films. The PVC/ZnO nanocomposite films consist of the addition of different concentrations with both non-annealed ZnO nanoparticles and ZnO nanoparticles annealed at temperature of 700°C. The PVC/ZnO nanocomposite films by weight concentrations of (0 wt.%, 2.5 wt.%, 5 wt.% and 10 wt.%) have been prepared by the casting method. The optical absorbance and transmittance values of the composites films were measured in the wavelength range between (250 to 1100 nm) at room temperature by using the UV-1800 Shimadzu spectrophotometer. The optical properties (absorption coefficient, dielectric constant, refractive index, and optical conductivity) have been investigated by the ultraviolet (UV) spectrophotometer. The optical parameters (direct optical energy gap, excitation energy for electronic transitions, the dispersion energy, static refractive index, static dielectric constant, optical oscillator strengths, the moments of optical spectrum, linear optical susceptibility, third-order nonlinear optical susceptibility, nonlinear refractive index, high-frequency dielectric constant, the carrier concentration to the effective mass ratio, the long wavelength refractive index and the plasma frequency) were calculated. The results showed that the optical properties behavior of the PVC/ZnO nanocomposite films was found to be dependent on the ZnO concentration, and photon wavelength. In addition, the results of the study show that the optical parameters can be influenced by alter the concentration of the nonannealed and annealed a ZnO nanoparticle in the PVC polymer matrix.

Multipole expansion of the retarded interatomic dispersion energy

Physica ◽  
1972 ◽  
Vol 59 (4) ◽  
pp. 609-633 ◽  
Author(s):  
M.A.J. Michels ◽  
L.G. Suttorp
Keyword(s):  
Multipole Expansion ◽  
Dispersion Energy
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