scholarly journals Kinetic Interaction of Hexan Conversion and Oxidation on the Surface of an Al2O3 Nanocatalyzer at Room  Temperature under the Effect of Gamma Radiation

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Hokman Mahmudov ◽  
Telman Suleymanov ◽  
Zumrud Sabzaliyeva ◽  
Gunel Imanova ◽  
Haji Vahid Akhundzada ◽  
...  
Keyword(s):  
Gamma Radiation ◽  
Electron Density ◽  
Room Temperature ◽  
Excess Electron ◽  
Radiation Defects ◽  
Chemical Bonds ◽  
Decomposition Processes ◽  
Liquid Oxide ◽  
Kinetic Interaction ◽  
Al2o3 Catalyst

The kinetic and temperature dependencies of the conversion of hexane to gas and liquid oxide products on the surface of the nano-Al2O3 catalyst in the homo and hetero phase were investigated and compared. The rate of hexane conversion in air in different phases at temperature ∆T = 180–2000 C was determined ((a) 10–15% from the homo phase in the hetero phase; (b) thermal 12–17%; (c) radiation-thermal 14–22%). It is shown that the excess electron density formed in radiation defects migrates from the surface to the adsorbents, thereby weakening the intramolecular chemical bonds of the adsorbent and accelerating the decomposition processes investigated.

scholarly journals Creation of pure non-crystalline diamond nanostructures via room temperature ion irradiation and subsequent thermal annealing

2021 ◽  
Author(s):  
Federico Picollo ◽  
Alfio Battiato ◽  
Federico Bosia ◽  
Fabio Scaffidi Muta ◽  
Paolo Olivero ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Group Iv ◽  
Chemical Bonds ◽  
Group Iv Elements ◽  
Silicon And Germanium ◽  
Subsequent Thermal Annealing

Carbon exhibits a remarkable range of structural forms, due to the availability of sp3, sp2 and sp1 chemical bonds. Contrarily to other group IV elements such as silicon and germanium,...

Electron Pairing and Chemical Bonds. Physical Meaning of Effective Pairs

1994 ◽  
Vol 59 (12) ◽  
pp. 2567-2578 ◽  
Author(s):  
Robert Ponec ◽  
Filip Uhlík
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Physical Meaning ◽  
Electron Density Distribution ◽  
Mutual Coupling ◽  
Population Analysis ◽  
Point Of View ◽  
Chemical Bonds ◽  
Conditional Probabilities ◽  
Electron Pairing

The physical meaning of the so-called effective pairs which have been introduced recently within the formalism of pair population analysis is discussed using the analysis of conditional probabilities of electron density distribution for electron 1 with the reference electron fixed in a certain point 2. It is demonstrated that from the point of view of the mutual coupling of electron motions, the effective pairs behave analogously to singlet pairs. Based on this finding, effective pairs can be interpreted as the fraction of singlet pairs that is directly involved in bonding.

scholarly journals Computational Insight into the Rope-Skipping Isomerization of Diarylether Cyclophanes

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2127
Author(s):  
Thomas J. Summers ◽  
Hrishikesh Tupkar ◽  
Tyler M. Ozvat ◽  
Zoë Tregillus ◽  
Kenneth A. Miller ◽  
...  
Keyword(s):  
Asymmetric Catalysis ◽  
Room Temperature ◽  
Chemical Bonds ◽  
Chiral Molecules ◽  
Free Energies ◽  
Design And Synthesis ◽  
The Impact ◽  
Rope Skipping ◽  
Temperature Factors ◽  
Insight Into

The restricted rotation of chemical bonds may lead to the formation of stable, conformationally chiral molecules. While the asymmetry in chiral molecules is generally observed in the presence of one or more stereocenters, asymmetry exhibited by conformational chirality in compounds lacking stereocenters, called atropisomerism, depends on structural and temperature factors that are still not fully understood. This atropisomerism is observed in natural diarylether heptanoids where the length of the intramolecular tether constrains the compounds to isolable enantiomers at room temperature. In this work, we examine the impact tether length has on the activation free energies to isomerization of a diarylether cyclophane substructure with a tether ranging from 6 to 14 carbons. Racemization activation energies are observed to decay from 48 kcal/mol for a 7-carbon tether to 9.2 kcal/mol for a 14-carbon tether. Synthetic efforts to experimentally test these constraints are also presented. This work will likely guide the design and synthesis of novel asymmetric cyclophanes that will be of interest in the catalysis community given the importance of atropisomeric ligands in the field of asymmetric catalysis.

scholarly journals Изменение характеристик переизлучающих волокон Y-11 и O-2 под действием гамма облучения

2020 ◽  
Vol 128 (12) ◽  
pp. 1973
Author(s):  
А.Ю. Афанасьев ◽  
А.Ю. Бояринцев ◽  
И.А. Голутвин ◽  
Э.М. Ибрагимова ◽  
А.И. Малахов ◽  
...  
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Room Temperature ◽  
Low Dose ◽  
Low Dose Rate ◽  
60Co Gamma ◽  
60Co Gamma Radiation

The effect of 60Co gamma radiation on the intensity of the reemitted light at the exit from WLS-fibers of Y-11 M and O-2 M type WLS fibers and the subsequent restoration of the characteristics of irradiated fibers after exposure to room temperature are investigated. Irradiation of a low dose rate (0.048 Mrad / h) to a dose of 1 Mrad leads to a slight decrease in the intensity of the reemitted light at the exit of both types of fibers, and with a further increase in the dose, the curve does not change. When irradiated with a dose rate of 0.158 Mrad / h, the characteristics of both types of fibers deteriorate significantly. When the irradiated samples are held at room temperature, fiber characteristics are restored.

Analysis and Interpretation of Microstructures after Liquid Oxide Corrosion

2010 ◽  
Vol 70 ◽  
pp. 114-129
Author(s):  
Jacques Poirier
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Room Temperature ◽  
Local Thermodynamic Equilibrium ◽  
High Alumina ◽  
Essential Information ◽  
Phase Rule ◽  
Liquid Oxide ◽  
Chemical Profiles ◽  
Solid Phases

Corrosion by liquid oxides is one of the most severe modes of degradations which limit the lifetime of the refractory linings. The study of the microstructures of corroded refractories provides essential information. However, the interpretation of the microscopic observations is difficult : - The refractories are multi-component and heterogeneous ceramics, - The microscopic observations are carried out at room temperature. They are not representative of the mineral and vitreous phases existing at high temperature, - During cooling, new solid phases appear by crystallization of liquid oxides. The composition of the vitreous phases also evolves with the temperature. Consequently, the information obtained is often limited. In this paper , we will present a method to analyse and interpret the microstructures of refractories after use. The concept of local thermodynamic equilibrium and the use of the phase rule make it possible to interpret the microstructures of corroded refractories, to explain the observed mineral zonation and to quantify the composition of the liquid phase at high temperature from chemical profiles established by S.E.M. Experimental data from corrosion of MgO-C, Al2O3-MgO and high alumina refractories will illustrate and validate this theoretical approach.

scholarly journals High-resolution neutron and X-ray diffraction room-temperature studies of an H-FABP–oleic acid complex: study of the internal water cluster and ligand binding by a transferred multipolar electron-density distribution

IUCrJ ◽  
2016 ◽  
Vol 3 (2) ◽  
pp. 115-126 ◽  
Author(s):  
E. I. Howard ◽  
B. Guillot ◽  
M. P. Blakeley ◽  
M. Haertlein ◽  
M. Moulin ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Fatty Acid ◽  
High Resolution ◽  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Room Temperature ◽  
Water Molecules ◽  
X Ray

Crystal diffraction data of heart fatty acid binding protein (H-FABP) in complex with oleic acid were measured at room temperature with high-resolution X-ray and neutron protein crystallography (0.98 and 1.90 Å resolution, respectively). These data provided very detailed information about the cluster of water molecules and the bound oleic acid in the H-FABP large internal cavity. The jointly refined X-ray/neutron structure of H-FABP was complemented by a transferred multipolar electron-density distribution using the parameters of the ELMAMII library. The resulting electron density allowed a precise determination of the electrostatic potential in the fatty acid (FA) binding pocket. Bader's quantum theory of atoms in molecules was then used to study interactions involving the internal water molecules, the FA and the protein. This approach showed H...H contacts of the FA with highly conserved hydrophobic residues known to play a role in the stabilization of long-chain FAs in the binding cavity. The determination of water hydrogen (deuterium) positions allowed the analysis of the orientation and electrostatic properties of the water molecules in the very ordered cluster. As a result, a significant alignment of the permanent dipoles of the water molecules with the protein electrostatic field was observed. This can be related to the dielectric properties of hydration layers around proteins, where the shielding of electrostatic interactions depends directly on the rotational degrees of freedom of the water molecules in the interface.

Formation and Electronic Structure of the Mn/GaAs(100) Interface

1992 ◽  
Vol 281 ◽  
Author(s):  
X. Jin ◽  
M. Zhang ◽  
G. S. Dong ◽  
Z. S. Li ◽  
Xun Wang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electron Density ◽  
Density Of States ◽  
Room Temperature ◽  
Early Stage ◽  
Ferromagnetic Phase ◽  
Two Dimensional ◽  
Interface Diffusion ◽  
Electron Density Of States ◽  
Fermi Edge

ABSTRACTFormation and electronic structure of the Mn/GaAs(100) interface grown at room temperature are studied by photoemission. The growth at early stage is identified to be in two-dimensional mode. The chemical reaction and the interface diffusion happened between Mn and GaAs are explored in some details. A ferromagnetic phase of Mn overlayer at early stage is deduced from the change of electron density of states near the Fermi edge.

Influence of Gamma Radiation on the Radiofrequency Dielectric Properties of Nigerian Crude Oil

2009 ◽  
Vol 62-64 ◽  
pp. 445-450
Author(s):  
O.D. Osahon ◽  
O.D. Nworgu
Keyword(s):  
Relaxation Time ◽  
Gamma Radiation ◽  
Crude Oil ◽  
Relative Permittivity ◽  
Room Temperature ◽  
Irradiation Time ◽  
Central Research ◽  
Dielectric Measurements ◽  
Frequency Range ◽  
Dielectric Data

This paper examines the relative permittivity of irradiated and non-irradiated crude oil samples in the frequency range 0.1 – 100.0MHz and room temperature regulated at 25 ± 1oC. Samples of crude oil of mean specific gravity 0.780 ± 0.015 were irradiated for periods of two, four, six, eight and ten months respectively using a gamma radiation source (Cobalt 60) at a dose rate of 0.65mSv per hour. Dielectric measurements were made by using a Boonton RX meter type 250A admittance bridge manufactured by central research Laboratories, Inc, Red, Wing, Minnesota. Analysis of the resulting dielectric data revealed that both the irradiated and non-irradiated samples exhibited dielectric dispersion over the frequency range investigated. However, the relative permittivity values of the irradiated samples were found to be higher than those of the non-irradiated sample. This difference is understandable as it can be attributed to the ionization of atoms and weakening of molecular bonds in the irradiated samples. The increase in relative permittivity for the irradiated samples was observed to be time dependent as the longer the time of irradiation of sample the higher the value of its relative permittivity. Also, in this study, it was observed that the non-irradiated crude oil sample has longer relaxation time than the irradiated ones. The relaxation time decreases gradually with increasing irradiation time. This has physical significance on the basis of the molecular theory of matter and the fact that relaxation time is inversely proportional to relaxation frequency. These results are comparable with the work of other researchers for which similar trends have been observed.

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