scholarly journals Plutonium complexes in water: new approach to ab initio modeling

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mikhail V. Ryzhkov ◽  
Andrei N. Enyashin ◽  
Bernard Delley
Keyword(s):  
Quantitative Estimation ◽  
Water Solution ◽  
Geometry Optimization ◽  
Model Potential ◽  
Water Dissociation ◽  
New Approach ◽  
Molecular Systems ◽  
Screening Model ◽  
Solvent Environment ◽  
Structure Calculations

Abstract Geometry optimization and the electronic structure calculations of Pu Z+ complexes (Z = 3–6) in water solution have been performed, within the framework of the DMol3 and Relativistic Discrete-Variational (RDV) methods. For the simulation of Pu Z+ molecular environment in aqueous solution we used 22 and 32 water molecules randomly distributed around cation. To model the effect of bulk solvent environment we used COSMO (Conductor-like Screening Model) potential for water (ε = 78.54). The obtained results showed that this approach allows the modeling of water dissociation and the formation of hydrolysis products. Our previously suggested scheme for the calculation of interaction energies between selected fragments of multi-molecular systems provides the quantitative estimation of the interaction strengths between plutonium in various oxidation states and each ligand in the first and second coordination shells in water solution.

Host-Guest Interactions on Electrode Surfaces for Immobilization of Molecular Catalysts

2020 ◽  
Author(s):  
Laurent Sévery ◽  
Jacek Szczerbiński ◽  
Mert Taskin ◽  
Isik Tuncay ◽  
Fernanda Brandalise Nunes ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Heterogeneous Systems ◽  
Catalytic Systems ◽  
New Approach ◽  
Molecular Systems ◽  
Electrode Surfaces ◽  
Catalytic Surfaces ◽  
Oxide Electrodes ◽  
The Stability ◽  
Molecular Catalysts

The strategy of anchoring molecular catalysts on electrode surfaces combines the high selectivity and activity of molecular systems with the practicality of heterogeneous systems. The stability of molecular catalysts is, however, far less than that of traditional heterogeneous electrocatalysts, and therefore a method to easily replace anchored molecular catalysts that have degraded could make such electrosynthetic systems more attractive. Here, we apply a non-covalent “click” chemistry approach to reversibly bind molecular electrocatalysts to electrode surfaces via host-guest complexation with surface-anchored cyclodextrins. The host-guest interaction is remarkably strong and allows the flow of electrons between the electrode and the guest catalyst. Electrosynthesis in both organic and aqueous media was demonstrated on metal oxide electrodes, with stability on the order of hours. The catalytic surfaces can be recycled by controlled release of the guest from the host cavities and readsorption of fresh guest. This strategy represents a new approach to practical molecular-based catalytic systems.

scholarly journals Quantum HF/DFT-embedding algorithms for electronic structure calculations: Scaling up to complex molecular systems

2021 ◽  
Vol 154 (11) ◽  
pp. 114105
Author(s):  
Max Rossmannek ◽  
Panagiotis Kl. Barkoutsos ◽  
Pauline J. Ollitrault ◽  
Ivano Tavernelli
Keyword(s):  
Electronic Structure ◽  
Electronic Structure Calculations ◽  
Scaling Up ◽  
Molecular Systems ◽  
Structure Calculations

scholarly journals The Singular Molecular Conformation of Humic Acids in Solution Influences Their Ability to Enhance Root Hydraulic Conductivity and Plant Growth

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 3
Author(s):  
Maite Olaetxea ◽  
Veronica Mora ◽  
Roberto Baigorri ◽  
Angel M. Zamarreño ◽  
Jose M. García-Mina
Keyword(s):  
Polyethylene Glycol ◽  
Humic Acid ◽  
Hydraulic Conductivity ◽  
Plant Growth ◽  
Polyacrylic Acid ◽  
Molecular Conformation ◽  
Water Solution ◽  
Biological Effects ◽  
Root Hydraulic Conductivity ◽  
Molecular Systems

Some studies have reported that the capacity of humic substances to improve plant growth is dependent on their ability to increase root hydraulic conductivity. It was proposed that this effect is directly related to the structural conformation in solution of these substances. To study this hypothesis, the effects on root hydraulic conductivity and growth of cucumber plants of a sedimentary humic acid and two polymers—polyacrylic acid and polyethylene glycol—presenting a molecular conformation in water solution different from that of the humic acid have been studied. The results show that whereas the humic acid caused an increase in root hydraulic conductivity and plant growth, both the polyacrylic acid and the polyethylene glycol did not modify plant growth and caused a decrease in root hydraulic conductivity. These results can be explained by the different molecular conformation in water solution of the three molecular systems. The relationships between these biological effects and the molecular conformation of the three molecular systems in water solution are discussed.

scholarly journals Spectral properties of coumarin derivatives in various environments

2013 ◽  
Vol 11 (4) ◽  
pp. 492-501 ◽  
Author(s):  
Alzbeta Holubekova ◽  
Pavel Mach ◽  
Jan Urban
Keyword(s):  
Gas Phase ◽  
Absorption Spectra ◽  
Spectral Properties ◽  
Density Functional ◽  
Water Solution ◽  
Blue Shift ◽  
Coumarin Derivatives ◽  
Complex Environments ◽  
Td Dft ◽  
Solvent Environment

AbstractThe structural and spectral properties of coumarin derivatives in complex environments were investigated within the time-dependent density functional theory (TD DFT). Absorption spectra calculations were obtained at TD PBE0/6-31+G(d,p) level of theory for coumarin47 in the gas-phase and in various polar and non-polar organic solvents. The geometries of coumarins 6, 30, 47 and 522 in the gas phase and in inclusion complexes with the β-cyclodextrin (βCD) were determined by PM3 and DFT (HCTH/6-31G) calculations. Encapsulation of coumarin in βCD and associated changes in electronic structure produced either a red or blue shift in the absorption spectra of coumarins. A proposed cavity model for βCD-coumarin complex in water solution allowed identification of various contributions to the overall shift in the absorption spectra of coumarin upon complex formation in a solvent environment

A 3D Model Watermarking Algorithm

2013 ◽  
Vol 798-799 ◽  
pp. 708-711
Author(s):  
Xiu Hu Tan
Keyword(s):  
Detection Probability ◽  
3D Model ◽  
False Alarm Probability ◽  
3D Models ◽  
Model Potential ◽  
Least Mean Square ◽  
New Approach ◽  
Geometry Model ◽  
3D Geometry ◽  
High Detection

The popularity of 3D content is on the rise since it provides an immersive experience to viewers. In this paper, we present a new approach to watermarking 3D models based on optimization statistics. Through choosing the vertexes, we are able to obtain to the embedded watermark that has the least modified to topology transform of the 3D geometry model, and then project the watermark to the space that has the least mean square error value. So, we obtain that the robustness of the approach lies in hiding a watermark in the space that is least susceptible to the 3D model potential modification. Through analysis and constraint the conditions, we can obtain a high detection probability, a low false alarm probability. The robustness of our method is demonstrated by various attacks through computer simulation.

Density Functional Theory Studies of Electronic Structures and Hyperfine Interactions of Muonium in Imidazole

2015 ◽  
Vol 749 ◽  
pp. 134-138 ◽  
Author(s):  
Pek Lan Toh ◽  
Shukri Sulaiman ◽  
Mohamed Ismail Mohamed Ibrahim ◽  
Lee Sin Ang
Keyword(s):  
Density Functional Theory ◽  
Electronic Structures ◽  
Density Functional ◽  
Hyperfine Interactions ◽  
Geometry Optimization ◽  
Optimization Procedure ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Total Energies ◽  
Structure Calculations

We carried out ab initio electronic structure calculations in the frameworks of the Density Functional Theory (DFT) to study the electronic structures and hyperfine interaction of muonium (Mu) in imidazole (C3H4N2) and 1–methylimidazole (CH3C3H3N2). The local energy minima and hyperfine interactions of the Mu trapped at the three studies sites were determined by performing geometry optimization procedure. The results show the total energies for all three studied sites are close to one another. The Mu hyperfine interactions were also determined, with the corresponding values vary from 343.00 MHz to 471.28 MHz for the imidazole–Mu cluster, and from 380.21 MHz – 465.57 MHz to 475.93 MHz for the cluster of 1–methylimidazole–Mu, respectively.

A New Scheme of Shell Model Potential for Hydrogen System

2010 ◽  
Vol 156-157 ◽  
pp. 1590-1593
Author(s):  
Xun Wang ◽  
Hong Sun ◽  
Yue Hua Wang ◽  
Zhen Ning Ma ◽  
Qing Jie Wang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Energy Level ◽  
Ab Initio ◽  
Shell Model ◽  
Ab Initio Calculation ◽  
Geometry Optimization ◽  
Model Potential ◽  
Trigonometric Function ◽  
Hydrogen System ◽  
Calculation Results

The shell model (SM) can simulate dipole and other properties concerning electrons. In this paper, an new scheme of SM potential is developed. Unlike the traditional SM, there are no harmonic spring between core and shell, and the potential functions are Coulomb potential multiplied by trigonometric function. The parameters of SM for hydrogen system were fitted by electronic structure data, which is from quantum chemistry ab initio calculation of H, + 2 H and 2 H . And the potential was examined by calculating the most stable structure of H2 and + 2 H by geometry optimization globally, which is agree with the ab initio calculation results. Furthermore, even the energy level of H atom can be calculated by this scheme SM potential, but the reasonable results can not obtained.

scholarly journals An Experimental Study for Quantitative Estimation of Rebar Corrosion in Concrete Using Ground Penetrating Radar

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Md Istiaque Hasan ◽  
Nur Yazdani
Keyword(s):  
Reinforced Concrete ◽  
Quantitative Estimation ◽  
Salt Water ◽  
Water Solution ◽  
Maximum Amplitude ◽  
Accelerated Corrosion ◽  
Oil Emulsion ◽  
Steel Rebar ◽  
Ground Penetrating ◽  
The Relationship

Corrosion of steel rebar in reinforced concrete is one the most important durability issues in the service life of a structure. In this paper, an investigation is conducted to find out the relationship between the amount of reinforced concrete corrosion and GPR maximum positive amplitude. Accelerated corrosion was simulated in the lab by impressing direct current into steel rebar that was submerged in a 5% salt water solution. The amount of corrosion was varied in the rebars with different levels of mass loss ranging from 0% to 45%. The corroded rebars were then placed into three different oil emulsion tanks having different dielectric properties similar to concrete. The maximum amplitudes from the corroded bars were recorded. A linear relationship between the maximum positive amplitudes and the amount of corrosion in terms of percentage loss of area was observed. It was proposed that the relationship between the GPR maximum amplitude and the amount of corrosion can be used as a basis of a NDE technique of quantitative estimation of corrosion.

A new approach to the measurement of the quantitative effects of inherent and environmental factors on the composition of the milk of individual cows and of herds, with particular reference to lactose content

1968 ◽  
Vol 35 (1) ◽  
pp. 91-105 ◽  
Author(s):  
J. P. Walsh ◽  
J. A. F. Rook ◽  
F. H. Dodd
Keyword(s):  
Quantitative Estimation ◽  
Relative Importance ◽  
New Approach ◽  
Mean Values ◽  
Stage Of Lactation ◽  
Bulk Milk ◽  
Wide Range ◽  
The Mean ◽  
The Difference ◽  
Effect Of Age

Summary(1) A tentative scheme is proposed for the quantitative estimation of the effects of various factors on one major milk constituent, lactose, from analyses of the milk of individual cows within herds. The potential lactose content in the milk of individual cows is predicted from the observed potassium-to-lactose ratio in the milk, and the difference between the predicted potential and the actual lactose content is partitioned into fractions that are attributed to effects due to age, inter-quarter difference and changes with stage of lactation. The scheme was applied to 2 commercial herds, one (herd A) producing milk of low and the other (herd B) milk of normal SNF content.(2) Lactation mean values for fat, SNF and lactose contents of the milk of individual cows showed a wide range of the same order in each of the 2 herds. Of the mean difference in SNF percentage of 0·30 between the herds, 0·14, or 47%, was due to a difference in lactose content.(3) The predicted potential milk lactose content of the cows in the 2 herds ranged from 5·04 to 5·66 (g/100 g milk water). Herd mean values were 5·394 for herd A and 5·244 for herd B.(4) Herd mean values for the effect on the lactose content (g/100 g milk water) of age, of changes with stage of lactation and of inter-quarter difference were −0·127, −0·080, and 0·073 respectively in herd A, and −0·197, −0·058 and −0·078, respectively, in herd B.(5) The relative importance of the various factors in accounting for differences between the herds in the lactose content of their bulk milk were: predicted potential lactose content 61%, effect of age 28%, effect of changes with stage of lactation 9% and effect of inter-quarter difference 2%.(6) The errors attached to the estimation of potential milk lactose content and the effects of age, of changes with stage of lactation and of inter-quarter difference are discussed.

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