scholarly journals The Role of Quantum Dynamics in Covalent Bonding – A Comparison of the Thomas-Fermi and Hückel Models

10.5772/36698 ◽  
2012 ◽  
Author(s):  
Sture Nordholm ◽  
George B.
Keyword(s):  
Quantum Dynamics ◽  
Covalent Bonding ◽  
Thomas Fermi

THE NOTHING THAT REALLY IS!

2016 ◽  
Vol 12 (1) ◽  
pp. 4172-4177
Author(s):  
Abdul Malek
Keyword(s):  
Quantum Dynamics ◽  
Theoretical Physics ◽  
Historical Evolution ◽  
Proper Understanding ◽  
Physical Universe ◽  
Wave Particle Duality ◽  
Negative Effect ◽  
Materialist Interpretation

The denial of the existence of contradiction is at the root of all idealism in epistemology and the cause for alienations.  This alienation has become a hindrance for the understanding of the nature and the historical evolution mathematics itself and its role as an instrument in the enquiry of the physical universe (1). A dialectical materialist approach incorporating  the role of the contradiction of the unity of the opposites, chance and necessity etc., can provide a proper understanding of the historical evolution of mathematics and  may ameliorate  the negative effect of the alienation in modern theoretical physics and cosmology. The dialectical view also offers a more plausible materialist interpretation of the bewildering wave-particle duality in quantum dynamics (2).

scholarly journals EDEM2 stably disulfide-bonded to TXNDC11 catalyzes the first mannose trimming step in mammalian glycoprotein ERAD

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ginto George ◽  
Satoshi Ninagawa ◽  
Hirokazu Yagi ◽  
Taiki Saito ◽  
Tokiro Ishikawa ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Gene Knockout ◽  
Covalent Bonding ◽  
Cxxc Motif ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Endoplasmic Reticulum Protein ◽  
Hct116 Cells

Sequential mannose trimming of N-glycan (Man9GlcNAc2 -> Man8GlcNAc2 -> Man7GlcNAc2) facilitates endoplasmic reticulum-associated degradation of misfolded glycoproteins (gpERAD). Our gene knockout experiments in human HCT116 cells have revealed that EDEM2 is required for the first step. However, it was previously shown that purified EDEM2 exhibited no α1,2-mannosidase activity toward Man9GlcNAc2 in vitro. Here, we found that EDEM2 was stably disulfide-bonded to TXNDC11, an endoplasmic reticulum protein containing five thioredoxin (Trx)-like domains. C558 present outside of the mannosidase homology domain of EDEM2 was linked to C692 in Trx5, which solely contains the CXXC motif in TXNDC11. This covalent bonding was essential for mannose trimming and subsequent gpERAD in HCT116 cells. Furthermore, EDEM2-TXNDC11 complex purified from transfected HCT116 cells converted Man9GlcNAc2 to Man8GlcNAc2(isomerB) in vitro. Our results establish the role of EDEM2 as an initiator of gpERAD, and represent the first clear demonstration of in vitro mannosidase activity of EDEM family proteins.

scholarly journals Comparison between the Thomas–Fermi and Hartree–Fock–Bogoliubov Methods in the Inner Crust of a Neutron Star: The Role of Pairing Correlations

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 206
Author(s):  
Matthew Shelley ◽  
Alessandro Pastore
Keyword(s):  
Neutron Star ◽  
Mean Field ◽  
Pairing Correlation ◽  
Field Methods ◽  
Density Region ◽  
Thomas Fermi ◽  
Hartree Fock ◽  
Pairing Correlations ◽  
Mean Field Methods

We investigated the role of a pairing correlation in the chemical composition of the inner crust of a neutron star with the extended Thomas–Fermi method, using the Strutinsky integral correction. We compare our results with the fully self-consistent Hartree–Fock–Bogoliubov approach, showing that the resulting discrepancy, apart from the very low density region, is compatible with the typical accuracy we can achieve with standard mean-field methods.

Chlorine nuclear quadrupole resonance in mercury chlorides and complex chlorides

1971 ◽  
Vol 24 (9) ◽  
pp. 1753 ◽  
Author(s):  
DE Scaife
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Covalent Bonding ◽  
Distorted Octahedral ◽  
Resonance Frequencies ◽  
Quadrupole Resonance ◽  
Unknown Structure ◽  
Linear Molecules ◽  
Nuclear Quadrupole ◽  
Solid Compounds

Chlorine nuclear quadrupole resonance frequencies are reported for solid compounds of known structure containing linear molecules HgCl2 and Hg2Cl2, approximately trigonal HgCl3-, and a variety of distorted octahedral forms including NH4HgCl3, CsHgCl3, and K2HgCl4,H2O. Compounds of unknown structure of the type (cation+)HgCl3, (cation+)2HgCl4, (cation+)Hg2Cl5, (cation+)2Hg9Cl20, and (cation+)4HgCl6 have also been studied. There are clear correlations between observed n.q.r. frequencies and Hg-Cl infrared stretching frequencies and bond distances. These correlations show the dependence of the degree of covalent bonding in the Hg-Cl bond with distance. The n.q.r. data confirm that many of the complex chlorides of mercury are built up by the joining of octahedral HgCl6 units, distorted in such a way as to preserve to varying extents the identity of the HgCl2 molecule. ��� Predictions of the structures are made for some complex chlorides of unknown structure, and the role of bridging in building up the compounds is discussed in terms of observed n.q.r. data for bridging chlorines.

Role of parametric noise in nonintegrable quantum dynamics

1994 ◽  
Vol 49 (4) ◽  
pp. R2509-R2512 ◽  
Author(s):  
Rainer Scharf ◽  
Bala Sundaram
Keyword(s):  
Quantum Dynamics ◽  
Parametric Noise

scholarly journals Quantum or Classical Perception of Atomic Motion

2021 ◽  
pp. 195-221
Author(s):  
John S. Briggs
Keyword(s):  
Quantum Dynamics ◽  
Related Question ◽  
Atomic Motion ◽  
Historical Overview ◽  
Single Particles ◽  
Unitary Evolution ◽  
Wavefunction Collapse ◽  
Classical Perception

AbstractAn assessment is given as to the extent to which pure unitary evolution, as distinct from environmental decohering interaction, can provide the transition necessary for an observer to perceive quantum dynamics as classical. This has implications for the interpretation of quantum wavefunctions as a characteristic of ensembles or of single particles and the related question of wavefunction “collapse”. A brief historical overview is presented as well as recent emphasis on the role of the semi-classical “imaging theorem” in describing quantum to classical unitary evolution.

scholarly journals Flexible Chemiresistive Nitrogen Oxides Sensors Based on a Nanocomposite of Polypyrrole- Reduced Graphene Oxide Grafted Carboxybenzene Diazonium Salts.

2021 ◽  
Author(s):  
Djamil GUETTICHE ◽  
Ahmed MEKKI ◽  
BENMOULOUD Lilia ◽  
Tighilt Fatma-zohra ◽  
Amar BOUDJELLAL
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Spin Coating ◽  
Diazonium Salt ◽  
Covalent Bonding ◽  
Diazonium Salts ◽  
Reduced Graphene ◽  
One Step ◽  
Higher Sensitivity

Abstract Nanocomposites of polypyrrole/reduced graphene oxide (PPy/rGO) and polypyrrole/ functionalized reduced graphene oxide with aryl 4-carboxybenzene diazonium salt (PPy/rGO-aryl-COOH) were prepared through covalent bonding by simple one-step chemical oxidative synthesis. The as-prepared nanocomposites were deposited on BOPET substrate by spin coating to test their chemiresistive sensitivity properties on a homemade modular for online detection of (NO2) vapors at ambient temperature. Results showed that PPy/rGO-aryl-COOH forms a homogeneous nanocomposite within the size of 80 nanometers and improvement of the crystalline ordering. The more enhanced NO2 sensing properties have been shown by PPy/rGO- aryl-COOH in terms of higher sensitivity (1.01%/ppm), the faster response time (129 s), and the detection limit of (2ppm). Reproducibility features were also investigated.Moreover, humidity rates and temperature effects were also tested. Finally, impedance spectroscopy is conducted in the fresh air and in the presence of gas. These results highlight the paramount role of functionalization of reduced graphene oxide (rGO-aryl-COOH).

scholarly journals A Fragment Diabatization Linear Vibronic Coupling Model for Quantum Dynamics of Multichromophoric Systems: Population of the Charge Transfer State in the Photoexcited Guanine Cytosine Pair

2021 ◽  
Author(s):  
James Green ◽  
Martha Yaghoubi Jouybari ◽  
Haritha Asha ◽  
Fabrizio Santoro ◽  
Roberto Improta
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Quantum Dynamics ◽  
Reorganization Energy ◽  
Coupling Model ◽  
Vibronic Coupling ◽  
Strongly Coupled ◽  
Exciton Localization ◽  
Td Dft

<div>We introduce a method (FrD-LVC) based on a fragment diabatization (FrD) for the parametrization of a Linear Vibronic Coupling (LVC) model suitable for studying the photophysics of multichromophore systems. In combination with effective quantum dynamics (QD) propagations with multilayer multiconfigurational time-dependent Hartree (ML-MCTDH), the FrD-LVC approach gives access to the study of the competition between intra-chromophore decays, like those at conical intersections, and inter-chromophore processes, like exciton localization/delocalization and the involvement of charge transfer (CT) states. We used FrD-LVC parametrized with TD-DFT calculations, adopting either CAM-B3LYP or ωB97X-D functionals, to study the ultrafast photoexcited QD of a Guanine-Cytosine (GC) hydrogen bonded pair, within a Watson-Crick arrangement, considering up to 12 coupled diabatic electronic states and the effect of all the 99 vibrational coordinates. The bright excited states localized on C and, especially, on G are predicted to be strongly coupled to the G->C CT state which is efficiently and quickly populated after an excitation to any of the four lowest energy bright local excited states. Our QD simulations show that more than 80% of the excited population on G and ~50% of that on C decays to this CT state in less than 50 fs. We investigate the role of vibronic effects in the population of the CT state and show it depends mainly on its large reorganization energy so that it can occur even when it is significantly less stable than the bright states in the Franck-Condon region. At the same time, we document that the formation of the GC pair almost suppresses the involvement of dark nπ* excited states in the photoactivated dynamics.</div>

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