scholarly journals Dinâmica Molecular Ab Initio da Complexarão de Íons zinco com a vitamina C em Fase Gasosa

2020 ◽  
Author(s):  
Wilson Roberto Lopes Filho ◽  
Yago F. Lopes ◽  
Lilian T. F. de M. Camargo ◽  
Ademir J. Camargo
Keyword(s):  
Molecular Dynamics ◽  
Vitamin C ◽  
Ab Initio ◽  
High Stability ◽  
Average Distance ◽  
Zinc Ion ◽  
Food Supplement ◽  
The Body ◽  
New Drugs ◽  
Zinc Ions

Zinc and vitamin C are essential micronutrients for the conservation of the human body, being essential for the maintenance of the immune system, reducing the risk, severity and duration of infectious diseases. They are taken together as a food supplement, resulting in the improvement of pneumonia and malaria infections. Vitamin C and zinc are also associated with measures of obesity and adiposity. Studies report that vitamin C complexed in zinc promotes adipogenesis and stimulates the generation of insulin-responsive adipocytes. Therefore, since vitamin C together with zinc are fundamental for the body, and that vitamin C complexed with zinc can promote adipogenesis and stimulate the generation of adipocytes responsive to insulin, the study of the interaction between these micronutrients will broaden the understanding of its bioactivity, which may be important in the study of a new use of vitamin C and zinc combined. Thus, it is intended to study the complexation of Vitamin C with the zinc ion using simulations of Molecular Dynamics ab initio. Through the results of the dynamics, it is found that zinc interacted significantly with 3 atoms of vitamin C, thus identifying the formation of a tridentate complex, since the average distances between the metal and these atoms were between 2.176 and 2.261 Å. A decrease in the free Helmholtz energy is perceived as the zinc approaches these atoms, up to a distance of high stability, which corresponds to the average distance of these interactions. It is also evident that the complexation energy is -220,64 Kcal/mol indicating that the complexation is energetically favorable and that the complex formed is stable. Therefore, the results obtained broadened the knowledge about the complexation of zinc ions with vitamin C, which will be of great importance for the understanding of its bioactivity and in the planning of new drugs.

scholarly journals Zinc ion adsorption on carbon nanotubes in an aqueous solution

2012 ◽  
Vol 14 (3) ◽  
pp. 29-37 ◽  
Author(s):  
A. Ansari ◽  
M.A. Mehrabian ◽  
H. Hashemipour
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Adsorption Process ◽  
Electrostatic Force ◽  
Zinc Ion ◽  
Dynamics Simulation ◽  
Ion Adsorption ◽  
Zinc Ions ◽  
Interaction Energies ◽  
Water Layers

The literature devoted to numerical investigation of adsorption of heavy metal ions on carbon nanotubes is scarce. In this paper molecular dynamics is used to simulate the adsorption process and to investigate the effect of the infl uencing parameters on the rate of adsorption. The predictions of the molecular dynamics simulation show that the adsorption process is improved with increasing the temperature, pH of solution, the mass of nanotubes, and surface modifi cation of CNT using hydroxyl and carboxyl functional groups. The results predicted by the model are compared with the experimental results available in the literature; the close agreement validates the accuracy of the predictions. This study reveals that the water layers around the carbon nanotubes and the interaction energies play important roles in the adsorption process. The study also shows that electrostatic force controls the attraction of zinc ions on the nanotube sidewall.

scholarly journals Zinc Induced Aβ16 Aggregation Modeled by Molecular Dynamics

2021 ◽  
Vol 22 (22) ◽  
pp. 12161
Author(s):  
Anna P. Tolstova ◽  
Alexander A. Makarov ◽  
Alexei A. Adzhubei
Keyword(s):  
Molecular Dynamics ◽  
Metal Binding ◽  
Amyloid Fibrils ◽  
Beta Amyloid ◽  
Zinc Ion ◽  
Amyloid Peptide ◽  
Zinc Ions ◽  
Amyloid Peptides ◽  
Induced Aggregation ◽  
Favorable Structure

It is widely accepted that the addition of zinc leads to the formation of neurotoxic nonfibrillar aggregates of beta-amyloid peptides Aβ40 and Aβ42 and at the same time destabilizes amyloid fibrils. However, the mechanism of the effect of zinc on beta-amyloid is not fully understood. In this study, a fast zinc-induced aggregation of Aβ16 (as compared to a system without zinc) via the formation of Aβ16 dimers with one zinc ion coordinated in the metal-binding site 11EVHH14, followed by their polymerization, has been studied by molecular dynamics. The best aggregation was shown by the system composed of Aβ16 dimers bound by one zinc ion, with no additional zinc in solution. The presence of Aβ16 dimers was a major condition, sufficient for fast aggregation into larger complexes. It has been shown that the addition of zinc to a system with already formed dimers does not substantially affect the characteristics and rate of aggregation. At the same time, an excessive concentration of zinc at the early stages of the formation of conglomerates can negatively affect aggregation, since in systems where zinc ions occupied the 11EVHH14 coordination center and the His6 residue of every Aβ16 monomer, the aggregation proceeded more slowly and the resulting complexes were not as large as in the zinc-free Aβ system. Thus, this study has shown that the formation of Aβ16 dimers bound through zinc ions at the 11EVHH14 sites of the peptides plays an important role in the formation of neurotoxic non-fibrillar aggregates of beta-amyloid peptide Aβ16. The best energetically favorable structure has been obtained for the complex of two Aβ16 dimers with two zinc ions.

Ab Initio Molecular Dynamics Simulations of Cu under Vacuum and 473~1573K

2013 ◽  
Vol 690-693 ◽  
pp. 2699-2702
Author(s):  
Shu Hong Sun ◽  
Xiu Min Chen ◽  
Feng Xia Zhang ◽  
Bin Yang
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Ab Initio ◽  
Average Distance ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Partial Density ◽  
Structure And Properties ◽  
Calculation Results ◽  
Dynamics Simulations

The structure and properties simulation of Cu under vacuum were studied by ab initio molecular dynamics simulation. The calculation results were characterized in terms of radial distribution function (RDF), coordination number (CN) and partial density of states (PDOS). The results show that the average distance between atoms increased with the temperature, while CN decreased, which indicated an obvious improvement of the thermal motion between atoms. The simulation datas showed that the liquid phase appeared in the system when the temperature arrived 1373K,which close to the melting point(1357K) of copper.

Perbandingan Efek Suplementasi Tablet Tambah Darah Dengan Dan Tanpa Vitamin C Terhadap Kadar Hemoglobin Pada Ibu Hamil Dengan Usiakehamilan 16-32 Minggu Di Desa Keniten Kecamatan Mojo Kabupaten Kediri

2017 ◽  
Vol 3 (1) ◽  
pp. 76
Author(s):  
Siti Asiyah ◽  
Dwi Estuning Rahayu ◽  
Wiranti Dwi Novita Isnaeni
Keyword(s):  
Treatment Group ◽  
Vitamin C ◽  
Gestational Age ◽  
Group Treatment ◽  
Sampling Technique ◽  
Hemoglobin Level ◽  
The Body ◽  
Control Group ◽  
Fetal Organ ◽  
And Control

The needed of Iron Tablet in pregnancy was increase than mother who not pregnant.  That  cause of  high metabolism at the pregnancy for formed of  fetal organ and energy. One of effort for prevent anemia in mother pregnant with giving the Iron tablet and vitamin c. The reason of  this research in 4 June – 11 July 2014 is for compare the effect of  iron tablet suplementation with and without vitamin C toward Hemoglobin level in mother pregnant With Gestational Age Of 16-32 Weeks In Desa Keniten Kecamatan Mojo Kabupaten Kediri. This research method using comparative analytical.  Research design type of Quasy Eksperiment that have treatment group and control group. Treatment group will giving by Iron tablet and 100 mg vitamin C, and control group just giving by iron tablet during 21 days. Population in this research are all of mother pregnant with Gestational Age Of 16-32 Weeks with Sampling technique is  cluster random sampling is 29 mother pregnant. Comparison analysis of  iron tablet suplementation effect with and without vitamin C toward Hemoglobin level in mother pregnant With Gestational Age Of 16-32 Weeks, data analysis using Mann Whitney U-test and the calculated U value (44,5) less than U-table (51). So there was difference of iron tablet suplementation effect with and without vitamin C toward Hemoglobin level in mother pregnant With Gestational Age Of 16-32 Weeks Therefore, the addition of vitamin C on iron intake is needed to increase the uptake of iron tablets. When the amount of iron uptake increases, the reserves of iron in the body will also increase, so as to prevent anemia in pregnant women; Keywords : Iron Tablet (Fe), Vitamin C, Hemoglobin level, Mother Pregnant

Combustion Driven by Fragment-based Ab Initio Molecular Dynamics Simulation

2019 ◽  
Author(s):  
Liqun Cao ◽  
Jinzhe Zeng ◽  
Mingyuan Xu ◽  
Chih-Hao Chin ◽  
Tong Zhu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Large Scale ◽  
Methane Combustion ◽  
Combustion Method ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Computational Time ◽  
Combustion Mechanism ◽  
Daily Lives

Combustion is a kind of important reaction that affects people's daily lives and the development of aerospace. Exploring the reaction mechanism contributes to the understanding of combustion and the more efficient use of fuels. Ab initio quantum mechanical (QM) calculation is precise but limited by its computational time for large-scale systems. In order to carry out reactive molecular dynamics (MD) simulation for combustion accurately and quickly, we develop the MFCC-combustion method in this study, which calculates the interaction between atoms using QM method at the level of MN15/6-31G(d). Each molecule in systems is treated as a fragment, and when the distance between any two atoms in different molecules is greater than 3.5 Å, a new fragment involved two molecules is produced in order to consider the two-body interaction. The deviations of MFCC-combustion from full system calculations are within a few kcal/mol, and the result clearly shows that the calculated energies of the different systems using MFCC-combustion are close to converging after the distance thresholds are larger than 3.5 Å for the two-body QM interactions. The methane combustion was studied with the MFCC-combustion method to explore the combustion mechanism of the methane-oxygen system.

Active Learning Accelerates Ab Initio Molecular Dynamics on Pericyclic Reactive Energy Surfaces

2020 ◽  
Author(s):  
Shi Jun Ang ◽  
Wujie Wang ◽  
Daniel Schwalbe-Koda ◽  
Simon Axelrod ◽  
Rafael Gomez-Bombarelli
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Transition State ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Computational Cost ◽  
Reactive Trajectories ◽  
Dynamics Simulations ◽  
Energy Surfaces

<div>Modeling dynamical effects in chemical reactions, such as post-transition state bifurcation, requires <i>ab initio</i> molecular dynamics simulations due to the breakdown of simpler static models like transition state theory. However, these simulations tend to be restricted to lower-accuracy electronic structure methods and scarce sampling because of their high computational cost. Here, we report the use of statistical learning to accelerate reactive molecular dynamics simulations by combining high-throughput ab initio calculations, graph-convolution interatomic potentials and active learning. This pipeline was demonstrated on an ambimodal trispericyclic reaction involving 8,8-dicyanoheptafulvene and 6,6-dimethylfulvene. With a dataset size of approximately</div><div>31,000 M062X/def2-SVP quantum mechanical calculations, the computational cost of exploring the reactive potential energy surface was reduced by an order of magnitude. Thousands of virtually costless picosecond-long reactive trajectories suggest that post-transition state bifurcation plays a minor role for the reaction in vacuum. Furthermore, a transfer-learning strategy effectively upgraded the potential energy surface to higher</div><div>levels of theory ((SMD-)M06-2X/def2-TZVPD in vacuum and three other solvents, as well as the more accurate DLPNO-DSD-PBEP86 D3BJ/def2-TZVPD) using about 10% additional calculations for each surface. Since the larger basis set and the dynamic correlation capture intramolecular non-covalent interactions more accurately, they uncover longer lifetimes for the charge-separated intermediate on the more accurate potential energy surfaces. The character of the intermediate switches from entropic to thermodynamic upon including implicit solvation effects, with lifetimes increasing with solvent polarity. Analysis of 2,000 reactive trajectories on the chloroform PES shows a qualitative agreement with the experimentally-reported periselectivity for this reaction. This overall approach is broadly applicable and opens a door to the study of dynamical effects in larger, previously-intractable reactive systems.</div>

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