Calcium magnesium phosphate granules: atomistic simulations explaining cell death.

1994 ◽  
Vol 190 (1) ◽  
pp. 131-139
Author(s):  
K Simkiss ◽  
M G Taylor
Keyword(s):  
Cell Death ◽  
Computer Simulations ◽  
Atomistic Simulations ◽  
Cell Physiology ◽  
Interatomic Potentials ◽  
Granule Formation ◽  
Crystal Lattices ◽  
Calcium Magnesium ◽  
Lattice Energies ◽  
Magnesium Phosphates

1. A large number of invertebrates have cells that produce intracellular granules of amorphous calcium magnesium phosphates that are thought to act as ion stores or sites of metal detoxification. 2. The interatomic potentials and force constants have been calculated for these ions, and computer simulations of the crystal lattices have been used to determine the effects of ion substitutions on these lattice energies. 3. The results provide insights into the mechanisms of granule formation and the effects of ion substitutions on cell physiology.

On the impact of lattice parameter accuracy of atomistic simulations on the microstructure of Ni-Ti shape memory alloys

2021 ◽  
Author(s):  
Lorenzo La Rosa ◽  
Francesco Maresca
Keyword(s):  
Molecular Dynamics ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Atomistic Simulations ◽  
Interatomic Potentials ◽  
The Impact

Abstract Ni-Ti is a key shape memory alloy (SMA) system for applications, being cheap and having good mechanical properties. Recently, atomistic simulations of Ni-Ti SMAs have been used with the purpose of revealing the nano-scale mechanisms that control superelasticity and the shape memory effect, which is crucial to guide alloying or processing strategies to improve materials performance. These atomistic simulations are based on molecular dynamics modelling that relies on (empirical) interatomic potentials. These simulations must reproduce accurately the mechanism of martensitic transformation and the microstructure that it originates, since this controls both superelasticity and the shape memory effect. As demonstrated by the energy minimization theory of martensitic transformations [Ball, James (1987) Archive for Rational Mechanics and Analysis, 100:13], the microstructure of martensite depends on the lattice parameters of the austenite and the martensite phases. Here, we compute the bounds of possible microstructural variations based on the experimental variations/uncertainties in the lattice parameter measurements. We show that both density functional theory and molecular dynamics lattice parameters are typically outside the experimental range, and that seemingly small deviations from this range induce large deviations from the experimental bounds of the microstructural predictions, with notable cases where unphysical microstructures are predicted to form. Therefore, our work points to a strategy for benchmarking and selecting interatomic potentials for atomistic modelling of shape memory alloys, which is crucial to modelling the development of martensitic microstructures and their impact on the shape memory effect.

scholarly journals Atomistic simulations of the aggregation of small aromatic molecules in homogenous and heterogenous mixtures

2020 ◽  
Vol 22 (37) ◽  
pp. 21005-21014
Author(s):  
Michael Thomas ◽  
Irene Suarez-Martinez ◽  
Li-Juan Yu ◽  
Amir Karton ◽  
Graham S. Chandler ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Computer Simulations ◽  
Cosmic Dust ◽  
Atomistic Simulations ◽  
Polyaromatic Hydrocarbon ◽  
Seed Formation ◽  
Aromatic Molecules ◽  
Dust Grain

We describe a mechanism and structural analysis for cosmic dust grain seed formation around carbon-rich stars via polyaromatic hydrocarbon aggregation using computer simulations.

State of water in amorphous calcium and calcium-magnesium phosphates

2008 ◽  
Vol 78 (5) ◽  
pp. 864-867 ◽  
Author(s):  
V. A. Sinyaev ◽  
R. Z. Le Geros ◽  
L. V. Levchenko ◽  
E. S. Shustikova ◽  
R. A. Karzhaubaeva
Keyword(s):  
State Of Water ◽  
Calcium Magnesium ◽  
Magnesium Phosphates

Gimap4 accelerates T-cell death

Blood ◽  
2006 ◽  
Vol 108 (2) ◽  
pp. 591-599 ◽  
Author(s):  
Silke Schnell ◽  
Corinne Démollière ◽  
Paul van den Berk ◽  
Heinz Jacobs
Keyword(s):  
Cell Death ◽  
T Cell ◽  
Critical Role ◽  
T Cell Development ◽  
Cell Receptor ◽  
Cell Physiology ◽  
Double Positive ◽  
Pkc Activation ◽  
Null Mutant Mouse

Gimap4, a member of the newly identified GTPase of the immunity-associated protein family (Gimap), is strongly induced by the pre–T-cell receptor in precursor T lymphocytes, transiently shut off in double-positive thymocytes, and reappears after TCR-mediated positive selection. Here, we show that Gimap4 remains expressed constitutively in the cytosol of mature T cells. A C-terminal IQ domain binds calmodulin in the absence of calcium, and conserved PKC phosphorylation motifs are targets of concanavalin A (ConA)– or PMA/ionomycin-induced PKC activation. To address the role of Gimap4 in T-cell physiology, we completed the genomic organization of the gimap4 locus and generated a Gimap4-null mutant mouse. Studies in these mice revealed no critical role of Gimap4 in T-cell development but in the regulation of apoptosis. We have found that Gimap4 accelerates the execution of programmed cell death induced by intrinsic stimuli downstream of caspase-3 activation and phosphatidylserine exposure. Apoptosis directly correlates with the phosphorylation status of Gimap4.

Atomistic Simulations for Multiscale Modeling in bcc Metals

1999 ◽  
Vol 121 (2) ◽  
pp. 120-125 ◽  
Author(s):  
John A. Moriarty ◽  
Wei Xu ◽  
Per So¨derlind ◽  
James Belak ◽  
Lin H. Yang ◽  
...  
Keyword(s):  
Multiscale Modeling ◽  
Strength Properties ◽  
Peierls Stress ◽  
Boundary Structure ◽  
Atomistic Simulations ◽  
Interatomic Potentials ◽  
Ideal Strength ◽  
Bcc Metals ◽  
Kink Pair ◽  
Grain Boundary Structure

Quantum-based atomistic simulations are being used to study fundamental deformation and defect properties relevant to the multiscale modeling of plasticity in bcc metals at both ambient and extreme conditions. Ab initio electronic-structure calculations on the elastic and ideal-strength properties of Ta and Mo help constrain and validate many-body interatomic potentials used to study grain boundaries and dislocations. The predicted Σ5 (310) [100] grain boundary structure for Mo has recently been confirmed in HREM measurements. The core structure, γ surfaces, Peierls stress, and kink-pair formation energies associated with the motion of a/2〈111〉 screw dislocations in Ta and Mo have also been calculated. Dislocation mobility and dislocation junction formation and breaking are currently under investigation.

Atomistic simulations of TeO2-based glasses: interatomic potentials and molecular dynamics

2014 ◽  
Vol 16 (27) ◽  
pp. 14150-14160 ◽  
Author(s):  
Anastasia Gulenko ◽  
Olivier Masson ◽  
Abid Berghout ◽  
David Hamani ◽  
Philippe Thomas
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Interatomic Potential ◽  
Atomistic Simulations ◽  
Interatomic Potentials ◽  
First Results ◽  
Dynamics Simulations

This article derives the interatomic potential for the TeO2 system and presents the first results of molecular dynamics simulations of the pure TeO2 structure.

Interatomic Potentials in Ioncovalent Solids

1988 ◽  
Vol 141 ◽  
Author(s):  
A.N. Cormack ◽  
C.R.A. Catlow
Keyword(s):  
Atomistic Simulations ◽  
Interatomic Potentials

AbstractThe use of interatomic potentials in the simulation of ionocovalent solids is discussed. Some of the problems that may arise in the application of atomistic simulations to these solids are highlighted and some criteria for the validation of interatomic potentials for this class of solids are presented.

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