scholarly journals A Theoretical and Experimental Study for Screening Inhibitors for Styrene Polymerization

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 677 ◽  
Author(s):  
Darvishi ◽  
Rahimpour ◽  
Raeissi
Keyword(s):  
Density Functional ◽  
Dft Calculation ◽  
Experimental Approach ◽  
Synergistic Effects ◽  
Nitroxide Radicals ◽  
Styrene Polymerization ◽  
Electrophilicity Index ◽  
Functional Theory ◽  
Tert Butyl ◽  
Stable Nitroxide

Styrene is one of the most important monomers utilized in the synthesis of various polymers. Nevertheless, during distillation, storage, and transportation of ST, undesired polymer (i.e., UP) formation can take place. Thus, the control of undesired polymerization of styrene is a challenging issue facing industry. To tackle the mentioned issue, the antipolymer and antioxidant activity of stable nitroxide radicals (i.e., SNRs) and phenolics in styrene polymerization were studied by density functional theory (DFT) calculation and experimental approach. The electrophilicity index and growth percentage have been determined by DFT calculation and experimental approach, respectively. It is depicted that 2,6-di-tert-butyl-4-methoxyphenol (DTBMP) and 2,6-di-tert-butyl-4-methylphenol (BHT) from phenolics, and 4-hydroxy-2,2,6,6-tetramethyl piperidine 1-Oxyl (4-hydroxy-TEMPO) and 4-oxo-2,2,6,6-tetramethylpiperidine 1-Oxyl (4-oxo-TEMPO) from stable nitroxide radicals were the most effective inhibitors. Also, the growth percentage of DTMBP, BHT, 4-hydroxy-TEMPO, and 4-oxo-TEMPO after 4 h were 16.40, 42.50, 24.85, and 46.8, respectively. In addition, the conversion percentage of DTMBP, BHT, 4-hydroxy-TEMPO, and 4-oxo-TEMPO after 4 h were obtained to be 0.048, 0.111, 0.065, and 0.134, respectively. Furthermore, the synergistic effect of these inhibitors was investigated experimentally, indicating that DTMBP/4-hydroxy-TEMPO exerted the best synergistic effects on the inhibition of polymerization. The optimum inhibition effect was observed at the blend of 4-hydroxy-TEMPO (25 wt.%) and DTMBP (75 wt.%,) corresponding to 6.8% polymer growth after 4 h.

scholarly journals DFT Insights into the Hydrodenitrogenation and Ring-Opening of Indole on an M (M = Ni, Pt, Ni–Pt) Slab Model

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1950
Author(s):  
Cuiping Wang ◽  
Jinpeng Chu ◽  
Lianji Zhang ◽  
Yan Huang ◽  
Zhiqiang Zhang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Ring Opening ◽  
Density Functional ◽  
Dft Calculation ◽  
Reaction Pathway ◽  
Synergistic Effects ◽  
Slab Model ◽  
Slab Surface ◽  
Functional Theory

Density functional theory (DFT) calculation has been used to study the hydrodenitrogenation (HDN) and ring-opening of indole on an M (M = Ni, Pt, Ni–Pt) slab surface. The possible reaction pathway of indole hydrogenation has been investigated in order to reveal the bimetallic synergistic effects of an M slab surface. Compared to the mechanism of indole hydrogenation on an M slab surface, it was found that a PtNi(111) surface favors indole hydrogenation. According to the results of DFT calculation, it suggests that the bimetallic effect of the M surface plays an important role in indole hydrogenation.

Ionic transfer mechanism of COS reaction with CaO: Inert marker experiment and density functional theory (DFT) calculation

AIChE Journal ◽  
2011 ◽  
Vol 58 (8) ◽  
pp. 2617-2620 ◽  
Author(s):  
Zhenchao Sun ◽  
Siwei Luo ◽  
Liang-Shih Fan
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Dft Calculation ◽  
Transfer Mechanism ◽  
Functional Theory ◽  
Ionic Transfer

scholarly journals Synthesis and Characterization of the Germathioacid Chloride Coordinated by an N-Heterocyclic Carbene §

Inorganics ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 76 ◽  
Author(s):  
Yasunobu Egawa ◽  
Chihiro Fukumoto ◽  
Koichiro Mikami ◽  
Nobuhiro Takeda ◽  
Masafumi Unno
Keyword(s):  
Carboxylic Acid ◽  
Density Functional ◽  
Dft Calculation ◽  
Acid Chlorides ◽  
Carboxylic Acid Chloride ◽  
Functional Theory ◽  
Nitrogen Ligands ◽  
Bond Property ◽  
Nitrogen Bonds

Carboxylic acid chlorides are useful substrates in organic chemistry. Many germanium analogues of carboxylic acid chloride have been synthesized so far. Nevertheless, all of the reported germathioacid chlorides use bidentate nitrogen ligands and contain germanium-nitrogen bonds. Our group synthesized germathioacid chloride, Ge(S)Cl{C6H3-2,6-Tip2}(Im-i-Pr2Me2), using N-heterocyclic carbene (Im-i-Pr2Me2). As a result of density functional theory (DFT) calculation, it was found that electrons are localized on sulfur, and the germanium-sulfur bond is a single bond with a slight double bond property.

Effect of Solute Ta on Grain Refinement of Al-7Si-0.3Mg Based Alloys

2022 ◽  
Vol 327 ◽  
pp. 54-64
Author(s):  
Ivo Spacil ◽  
David Holec ◽  
Peter Schumacher ◽  
Jiehua Li
Keyword(s):  
Grain Refinement ◽  
Density Functional ◽  
Dft Calculation ◽  
Interface Energy ◽  
Special Focus ◽  
Grain Refiner ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Sandwich Configuration ◽  
Scanning Electron

Different Ta concentrations together with stochiometric grain refiner (Al-2.2Ti-1B) in Al-Si-Mg based alloys were investigated with the aim to elucidate grain refinement mechanisms. Post-solidification microstructure was characterised using optical microscopy and scanning electron microscopy (SEM), with a special focus on the Ta-rich layer (more likely to be Al3Ta) on the basal planes (0001) of TiB2. A significant grain refinement was observed by using the solute Ta together with stochiometric grain refiner (Al-2.2Ti-1B). In order to further elucidate the formation of Ta-rich layer on the basal planes (0001) of TiB2, the Density Functional Theory (DFT) calculation were also performed to determine the interface energies of different interfaces and sandwich configurations, including Al (111), Al3Ti (112) and Al3Ta (112) at the interface of TiB2 basal plane (0001). It was found that the interface energy for Ti-terminated TiB2 at the interface throughout all configurations involved in this paper is lower than that for B-terminated TiB2, indicating that Ti-terminated TiB2 is more favourable. It was also found that the Al3Ta configuration yields the same interface energies as the Al3Ti configuration. Furthermore, the interface energy of the sandwich configuration also shows nearly identical values along the TiB2 // Al3Ti and TiB2 // Al3Ta interface energy, strongly indicating that the solute Ti can be fully replaced by the solute Ta.

scholarly journals Do two oxidants (ferric-peroxo and ferryl-oxo species) act in the biosynthesis of estrogens? A DFT calculation

RSC Advances ◽  
2018 ◽  
Vol 8 (27) ◽  
pp. 15196-15201 ◽  
Author(s):  
Xiang-Yun Wang ◽  
Hui-Min Yan ◽  
Yan-Li Han ◽  
Zhu-Xia Zhang ◽  
Xiao-Yun Zhang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Dft Calculation ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Two Oxidants ◽  
Ferric Peroxo

Density functional theory calculations were performed in order to reveal the mysterious catalytic step of the biosynthesis of estrogens.

Spin Alignment Studies on the Muon-Site Determination in La2CuO4

2020 ◽  
Vol 860 ◽  
pp. 154-159
Author(s):  
Muhammad Redo Ramadhan ◽  
Irwan Ramli ◽  
Dita Puspita Sari ◽  
Budhy Kurniawan ◽  
Azwar Manaf ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Potential Distribution ◽  
Density Functional ◽  
Dft Calculation ◽  
Minimum Energy ◽  
Point Dipole ◽  
Spin Alignment ◽  
Functional Theory ◽  
Muon Site ◽  
Insulating Gap

Here we report spin-alignment contributions to muon coordinate calculated utilizing density functional theory (DFT) calculation. We estimated four different antiferromagnetic (AF) spin alignments in La2CuO4. We observed small changes by adjusting spin configurations in DFT calculations. Cu-spin value of 0.61 µB is constant in all calculations. The insulating gap of 1.9 eV is unchanged in all configurations. Muon coordinate was defined as the most minimum energy in atomic potential distribution. By assuming that Cu-spin is a point dipole for each atom, internal fields for muon were calculated and compared to known experimental results.

scholarly journals DFT/QTAIM analysis of favipiravir adsorption on pristine and silicon doped C20 fullerenes

2019 ◽  
Vol 42 (1) ◽  
pp. 143-149 ◽  
Author(s):  
Özgür Alver ◽  
Cemal Parlak ◽  
Yunusa Umar ◽  
Ponnadurai Ramasami
Keyword(s):  
Drug Delivery ◽  
Density Functional ◽  
Topological Analysis ◽  
Binding Energies ◽  
Molecular Structures ◽  
Electrophilicity Index ◽  
Functional Theory ◽  
Drug Delivery Vehicles ◽  
Delivery Vehicles ◽  
Silicon Doped

Abstract Fullerenes have received attentions due to their versatile properties. Molecular structures and electronic properties namely binding energy, band gap, electrophilicity index and molecular topological analysis were studied for undoped and silicon doped C20 fullerenes and favipiravir in order to search for possible application of the systems as drug delivery vehicles. Density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) were used for the research. Molecular structures having the interaction edges of SiC19… OH in water and SiC19…C=O in gas phase were found as those most stable with binding energies of -57.28 kcal/mol and -43.46 kcal/mol correspondingly. The results and parameters found in this research may provide additional insights into drug delivery systems.

EMPIRICAL METHODS FOR ESTIMATING THE DETONATION PROPERTIES OF ENERGETIC TNAZ MOLECULAR DERIVATIVES

2004 ◽  
Vol 03 (03) ◽  
pp. 379-389 ◽  
Author(s):  
MIN-HSIEN LIU ◽  
CHENG CHEN ◽  
YAW-SHUN HONG
Keyword(s):  
Density Functional ◽  
Dft Calculation ◽  
Enthalpies Of Formation ◽  
Detonation Properties ◽  
Group Additivity ◽  
Detonation Pressure ◽  
Empirical Methods ◽  
Functional Theory ◽  
Simulation Results ◽  
Hybrid Density Functional

Following the successful synthesis of the TNAZ (1,3,3-trinitroazetidine), the amine reactant is theoretically replaced to yield the hypothesized TNAZ molecular derivatives. Hybrid density-functional theory (DFT) calculation method was applied to model TNAZ and its derivatives. In this investigation, the target molecular volumes were initially obtained using the group additivity approach, and then transferred into molecular densities. The densities and the least squares estimated enthalpies of formation (ΔHf) of TNAZ, and the corresponding derivatives, were obtained and the Kamlet–Jacobs empirical equations were used to determine the related detonation velocity and detonation pressure. The simulation results reveal that four of the TNAZ molecular derivatives perform similarly to the traditionally used RDX (1,3,5-trinitro-1,3,5-triazacyclohexane). Two other derivatives outperform RDX, with performance that approach that of HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane).

scholarly journals DFT Calculation on the Electronic Structure and Optical Properties of InxGa1-xN Alloy Semiconductors

2019 ◽  
Vol 26 (2) ◽  
pp. 127-132
Author(s):  
Xuewen WANG ◽  
Wenwen LIU ◽  
Chunxue ZHAI ◽  
Jiangni YUN ◽  
Zhiyong ZHANG
Keyword(s):  
Optical Properties ◽  
Absorption Spectrum ◽  
Electronic Structure ◽  
Density Functional ◽  
Dft Calculation ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Photoelectric Performance ◽  
The Density Functional Theory ◽  
Alloy Semiconductors

Using the density functional theory (DFT) of the first principle and Generalized gradient approximation method, the electronic structures and optical properties of the InxGa1-xN crystals with different x (x = 0.25, 0.5, 0.75, 1) have been calculated in this paper. The influence of the electronic structure on the properties has been analyzed. Then the influence of doping quantity on the characteristics has been summarized, which also indicates the trend of complex dielectric function, absorption spectrum and transitivity. With the increase of x, the computational result shows that the optical band gap (i.e.Eg) of the InxGa1-xN crystal tends to be narrow, then the absorption spectrum shifts to the low-energy direction. And the Fermi energy slightly moves to the bottom of conduction band which would cause the growth of conductivity by increasing x. In a word, the InxGa1-xN compound can be achieved theoretically the adjustable Eg and photoelectric performance with x, which will be used in making various optoelectronic devices including solar cell and sensors.

WORK FUNCTION OF BORON CARBIDE: A DFT CALCULATION

2012 ◽  
Vol 19 (04) ◽  
pp. 1250040 ◽  
Author(s):  
CHUNSHAN HE ◽  
ZHIBING LI ◽  
WEILIANG WANG
Keyword(s):  
Density Functional Theory ◽  
Boron Carbide ◽  
Work Function ◽  
Density Functional ◽  
Dft Calculation ◽  
Slab Model ◽  
Functional Theory ◽  
Work Functions

The work functions of (001) and (00-1) surfaces of B4C are investigated with density functional theory and symmetry slab model. These two surfaces are found to be almost nonpolarized and their work functions are 5.15 eV and 5.46 eV, respectively.

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