scholarly journals Ca and S K-edge XANES of CaS calculated by different methods: influence of full potential, core hole and Eu doping

2019 ◽  
Vol 26 (1) ◽  
pp. 152-158 ◽  
Author(s):  
Ondřej Šipr ◽  
Wilayat Khan ◽  
Yves Joly ◽  
Ján Minár
Keyword(s):  
Experimental Data ◽  
Scattering Method ◽  
Full Potential ◽  
Core Hole ◽  
Potential Core ◽  
Edge Structure ◽  
The Core ◽  
The Finite Difference Method ◽  
Multiple Scattering Method ◽  
Flapw Method

Ca and S K-edge spectra of CaS are calculated by the full-potential Green's function multiple-scattering method, by the FLAPW method and by the finite-difference method. All three techniques lead to similar spectra. Some differences remain close to the edge, both when comparing different calculations with each other and when comparing the calculations with earlier experimental data. Here it is found that using the full potential does not lead to significant improvement over the atomic spheres approximation and that the effect of the core hole can be limited to the photoabsorbing atom alone. Doping CaS with Eu will not affect the Ca and S K-edge XANES of CaS significantly but may give rise to a pre-edge structure not present for clean CaS.

STUDY OF ELECTRONIC STRUCTURE OF MgB2 BY MULTIPLE-SCATTERING CALCULATIONS OF B K-EDGE XANES

2002 ◽  
Vol 16 (11n12) ◽  
pp. 1605-1612
Author(s):  
ZIYU WU ◽  
N. L. SAINI ◽  
A. BIANCONI
Keyword(s):  
Multiple Scattering ◽  
Density Of States ◽  
Core Hole ◽  
Edge Structure ◽  
X Ray ◽  
The Core ◽  
Al Substitution ◽  
Band Structure Calculations ◽  
X Ray Absorption ◽  
Structure Calculations

The MgB 2 system is studied by self consistent multiple-scattering calculations at the B K-edge X-ray absorption near edge structure (XANES). We find that the features in the B K-edge XANES are strongly affected by medium and long range order with large influence of the core hole potential suggesting that the band structure calculations are not enough to provide a quantitative interpretation of the spectral features. We have investigated evolution of density of states in the conduction band as a function of Al substitution in place of the Mg. The results are consistent with the fact that the Al substitution influences mainly the density of states in the B σ-band and hence suppresses the superconductivity.

Electron energy loss near edge structure

1989 ◽  
Vol 47 ◽  
pp. 384-385
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Solid State ◽  
Energy Loss ◽  
Electron Energy ◽  
Golden Rule ◽  
Scattering Method ◽  
Edge Structure ◽  
Densities Of States ◽  
Dipole Selection Rule ◽  
Multiple Scattering Method ◽  
Electron Energy Loss

In inner shell absorption spectroscopy, the near edge structure (NES) up to 30 eV above threshold is a prominent solid state effect. It is well known that electron energy loss spectroscopy is advantageous for the study of light elements, like carbon, nitrogen, oxygen, and fluorine. Due to the complexity of the near edge region, it is only recently that a significant amount of research have been carried out to extract information on the solid state effects.The theory to interpret the near edge structure is based on Fermi’s Golden rule. Two methods have been derived which give different and complimentary physical pictures about the inner shell excitation process. Single electron band structure techniques have been successfully applied to the interpretation of x-ray near edge structure. using the projected densities of states (DOS) of L±1 characterpermitted by the dipole selection rule. The multiple scattering method views the near edge structure (XANES) [2.3] as coming from the interference between the outgoing ejected electron wave and renections from neighboring atoms.

Investigation of Local Coordination and Electronic Structure of Dielectric Thin Films from Theoretical Energy-Loss Spectra

2007 ◽  
Vol 996 ◽  
Author(s):  
Manish K. Singh ◽  
Javier Rosado ◽  
Rajesh Katamreddy ◽  
Anand Deshpande ◽  
Christos G. Takoudis
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Electronic Structure ◽  
Energy Loss ◽  
Density Functional ◽  
Random Phase ◽  
Dielectric Tensor ◽  
Full Potential ◽  
Low Loss ◽  
Edge Structure

AbstractQuantum mechanical simulations were performed to calculate the valence electron energy-loss spectra (VEELS) for hafnium oxide, hafnium silicate, silicon oxide and silicon systems using the full potential Linearized Augmented Plane Wave (LAPW) formalism within the Density Functional Theory (DFT) framework. The needed energy-loss function (ELF) was derived from the calculation of the complex dielectric tensor within the random phase approximation (RPA). The calculated spectra were compared with experimental scanning transmission electron microscopy (STEM)/EELS of atomic layer deposited (ALD) HfO2 on Si(100) to evaluate their use as a “fingerprint” method that can be used to distinguish among various polymorphs of HfO2 thin films and relate the fine structure to the electronic structure and local bonding environment. Calculated low-loss spectra are found to be in satisfactory agreement with experimental data. Also, the combination of such theoretical calculations and experimental data could be of key importance in our understanding of fundamental issues of these systems. Compared to energy-loss near edge structure (ELNES) or core energy-loss spectra, the ELF calculated for low-loss spectra is computationally less expensive and can prove useful for prompt analysis.

Exploring the Mechanism of Lingzhu San in Treating Febrile Seizures by Using Network Pharmacology

2020 ◽  
Vol 23 ◽  
Author(s):  
Xiao Zhou ◽  
Xiao-Fei Zhang ◽  
Dong-Yan Guo ◽  
Yan-Jun Yang ◽  
Lin Liu ◽  
...  
Keyword(s):  
Febrile Seizures ◽  
Network Pharmacology ◽  
Biological Processes ◽  
Active Compounds ◽  
Potential Core ◽  
R Language ◽  
The Core ◽  
Multiple Factors ◽  
Therapeutic Mechanism

Objective: Lingzhu San (LZS) is a traditional Chinese medicine (TCM) prescription which can be effective in treating febrile seizures (FS) and has few researches on the mechanisms. In order to better guide the clinical use of LZS, we used the research ideas and methods of network pharmacology to find the potential core compounds, targets and pathways of LZS in the complex TCM system for the treatment of FS, and predict the mechanism. Materials and Methods: Databases such as BATMAN, TCMSP, TCMID, and SWISS TARGET are used to mine the active compounds and targets of LZS, and the target information of FS was obtained through GENECARDS and OMIM. Using Venny2.1.0 and Cytoscape software to locked the potential core compounds and targets of FS. The R language and ClusterProfiler software package were adopt to enrich and analyze the KEGG and GO pathways of the core targets and the biological processes and potential mechanisms of the core targets were revealed. Results: 187 active compounds and 2113 target proteins of LZS were collected. And 38 potential core compounds, 35 core targets and 775 metabolic and functional pathways were screened which involved in mediating FS. Finally, the role of the core compounds, targets and pivotal pathways of LZS regulated FS in the pathogenesis and therapeutic mechanism of FS was discussed and clarified. Conclusions: In this paper, the multi-compounds, multi-targets and multi-pathways mechanism of LZS in the treatment of FS was preliminarily revealed through the analysis of network pharmacology data, which is consistent with the principle of multi-compounds compatibility of TCM prescriptions and unified treatment of diseases from multiple angles, and it provides a new way for TCM to treat complex diseases caused by multiple factors.

SEMIEMPIRICAL SCF–LCAO–MO TREATMENT OF THIOPHENE, FURAN, AND PYRROLE

1965 ◽  
Vol 43 (5) ◽  
pp. 1569-1576 ◽  
Author(s):  
N. Solony ◽  
F. W. Birss ◽  
John B. Greenshields
Keyword(s):  
Experimental Data ◽  
Satisfactory Agreement ◽  
Electronic Structures ◽  
Spectroscopic Data ◽  
Variable Parameter ◽  
Coulomb Repulsion ◽  
Resonance Integral ◽  
Electronic Transitions ◽  
The Core ◽  
Lcao Mo

The semiempirical SCF–LCAO–MO method of Pariser–Parr–Pople is utilized in the study of the π-electronic structures of thiophene, furan, and pyrrole. The core Hamiltonian expansion contains a Uz++ term, the potential due to the ionized hetero-atom contributing two electrons to the π-system. The γzz, one-center coulomb repulsion integral for the hetero-atom is evaluated from the experimental spectroscopic data only. With the resonance integral βczc as the only variable parameter, the calculated π*–π electronic transitions are in a satisfactory agreement with the experimental data.

Abstract P457: Systems Analysis To Understand The Impact Of The CDK Module On Cardiomyocyte Proliferation

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Bryana N Harris ◽  
Laura Woo ◽  
Jeffrey J Saucerman
Keyword(s):  
Experimental Data ◽  
Cell Cycle ◽  
Transcription Factor ◽  
Dna Synthesis ◽  
Current Knowledge ◽  
Cycle Phase ◽  
Cyclin D ◽  
Cardiomyocyte Proliferation ◽  
The Core ◽  
The Impact

Rationale: Heart failure is caused by the inability of adult mammalian hearts to overcome the loss of cardiomyocytes (CMs). This is due partly to the limited proliferative capacity of CMs, which exit the cell cycle and do not undergo cell division. Current knowledge in cardiac regeneration lacks an understanding of the molecular regulatory networks that determine whether CMs will progress through the cell cycle to proliferate. Our goal is to use computational modeling to understand the expression and activation levels of the core cell cycle network, specifically cyclins and cyclin-cyclin-dependent kinase (CDK) complexes. Methods: A model of core cell cycle dynamics was curated using previously published studies of CM proliferation regulators. This model incorporates those regulators known to stimulate G1/S and G2/M transitions through the core CDKs. The activity of each of the 22 network nodes (22 reactions) was predicted using a logic-based differential equation approach. The CDK model was then coupled with a minimal ODE model of cell cycle phase distributions and validated based on descriptions and experimental data from the literature. To prioritize key nodes for experimental validation, we performed a sensitivity analysis by stimulating individual knockdown for every node in the network, measuring the fractional activity of all nodes. Results: Our model confirmed that the knockdown of p21 and Rb protein and the overexpression of E2F transcription factor and cyclinD-cdk4 showed an increase in cells going through DNA synthesis and entering mitosis. A combined knockdown of p21 and p27 showed an increase of cells entering mitosis. Cyclin D-cdk4 and p21 overexpression showed a decrease and increase of Rb expression, respectively. Of the 14 model predictions, 12 agreed with experimental data in the literature. A comprehensive knockdown of the model nodes suggests that E2F (a key transcription factor driving DNA synthesis) is positively regulated by cyclin D while negatively regulated by GSK3B, SMAD3, and pRB. Conclusion: This model enables us to predict how cardiomyocytes respond to stimuli in the CDK network and identify potential therapeutic regulators that induce cardiomyocyte proliferation.

Prediction of Cavitation Inception Within Regions of Flow Separation

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
Flow Separation ◽  
Computational Method ◽  
Average Flow ◽  
Cavitation Inception ◽  
The Core ◽  
Good Agreement

Cavitation within regions of flow separation appears in drifting vortices. A two-part computational method is employed for prediction of cavitation inception number there. The first part is an analysis of the average flow in separation regions without consideration of an impact of vortices. The second part is an analysis of equilibrium of the bubble within the core of a vortex located in the turbulent flow of known average characteristics. Computed cavitation inception numbers for axisymmetric flows are in the good agreement with the known experimental data.

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