scholarly journals USING OF STICKY SPHERE MODEL FOR QUALITATIVE REPRODUCTION OF BASIC PHASE TRANSITIONS OF CYSTEINE-SILVER SOLUTION

2020 ◽  
pp. 252-259
Author(s):  
Максим Дмитриевич Малышев ◽  
Павел Михайлович Пахомов ◽  
Павел Вячеславович Комаров
Keyword(s):  
Phase Transitions ◽  
Salt Concentration ◽  
Software Package ◽  
Direct Impact ◽  
Sphere Model ◽  
Silver Solution ◽  
Gel Network ◽  
Silver Mercaptide ◽  
Basic Phase ◽  
Key Parameter

В настоящей работе сформулированная ранее мезоскопическая модель цистеин-серебряного раствора, в которой кластеры меркаптида серебра рассматриваются как жесткие «липкие» сферы, реализована на базе программного пакета LAMMPS. Ключевым параметром, оказывающим непосредственное влияние на морфологию формирующихся агрегатов и поведение системы в целом, является концентрация соли. Выполненные тестовые расчеты показывают, что построенная модель может воспроизводить этап созревания, образование волокон гель сетки и коагуляции цистеин-серебряного раствора на мезомасштабном уровне. In this work, the previously formulated mesoscopic model of a cysteine-silver solution, in which silver mercaptide clusters are considered as hard «sticky» spheres, is implemented on the basis of the LAMMPS software package. The key parameter that has a direct impact on the morphology of the forming aggregates and the behavior of the system depends on the salt concentration. The test calculations show that the constructed model can reproduce the stage of the maturation, the formation of the fibers of the gel-network and the coagulation of the cysteine-silver solution at the mesoscale level.

scholarly journals MESOSCOPIC SIMULATION OF STRUCTURAL TRANSITIONS IN CYSTEINE-SILVER SOLUTION

2021 ◽  
pp. 80-90
Author(s):  
Максим Дмитриевич Малышев ◽  
Павел Михайлович Пахомов ◽  
Павел Вячеславович Комаров
Keyword(s):  
Sol Gel ◽  
State Diagram ◽  
Pair Interaction ◽  
Structural Transitions ◽  
Modified Model ◽  
Mesoscopic Simulation ◽  
Silver Solution ◽  
Sol Gel Transition ◽  
Gel Network ◽  
Silver Mercaptide

Выполнено изучение структурных переходов в цистеин-серебряном растворе в зависимости от изменения концентрации соли - инициатора гелеобразования. Расчеты осуществлялись с использованием скорректированной мезоскопической модели, базирующейся на модели «липких сфер». Построена диаграмма состояний системы в координатах концентрация соли - энергия парного взаимодействия кластеров меркаптида серебра. Показано, что скорректированная модель хорошо воспроизводит все структурные превращения в цистеин-серебряном растворе: золь-гель переход, распад гель сетки и выпадения меркаптида серебра в осадок. The study of structural transitions in a cysteine-silver solution was carried out depending on the change in the concentration of the salt - the initiator of gelation. The calculations are carried out using a modified mesoscopic model based on the «sticky spheres» model. A state diagram was constructed in the coordinates - salt concentration, the pair interaction energy of silver mercaptide clusters. It is shown that the modified model reproduces well all structural transformations in a cysteine-silver solution: sol-gel transition, the disintegration of the gel network, and precipitation of silver mercaptide.

scholarly journals The Effect of Selected Anions on Dipalmitoylphosphatidylcholine Phase Transitions

2002 ◽  
Vol 57 (7-8) ◽  
pp. 712-716 ◽  
Author(s):  
Adriana Przyczyna ◽  
Bożenna Różycka-Roszk ◽  
Marek Langner
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Salt Concentration ◽  
Half Width ◽  
Main Phase ◽  
Interface Properties ◽  
Transition Enthalpy ◽  
Peak Half Width

The effect of three anions, Cl-, Br- and I-, on the phase transitions of dipalmitoylphosphatidylcholine (DPPC) was measured. Main phase transition was modestly affected by these anions in the salt concentration range 0.2 M. For Cl- and Br- the temperature of main phase transition was lower (by about 0.5 °C), its half-width modestly larger and enthalpy practically unchanged, all three parameters were altered to a much larger degree. Main phase transition temperature was 1.5 °C lower and the peak half-width significantly smaller. These changes were not accompanied by any alteration in main phase transition enthalpy. Iodide shifted the pretransition temperature toward lower values and increased its half-width to such an extent that at concentrations above 100 mm it was practically undetectable. Besides cations, the presence of anions also has a distinct effect on lipid bilayer interface properties.

scholarly journals Salt-Induced Swelling and Volume Phase Transition of Polyelectrolyte Gels

2017 ◽  
Vol 84 (5) ◽  
Author(s):  
Yalin Yu ◽  
Chad M. Landis ◽  
Rui Huang
Keyword(s):  
Phase Transitions ◽  
Salt Concentration ◽  
Volume Fraction ◽  
External Solution ◽  
Quantitative Agreement ◽  
Continuous Transition ◽  
Volume Phase ◽  
Polyelectrolyte Gels ◽  
Monovalent Ions ◽  
Polymer Solvent

A theoretical model of polyelectrolyte gels is presented to study continuous and discontinuous volume phase transitions induced by changing salt concentration in the external solution. Phase diagrams are constructed in terms of the polymer–solvent interaction parameters, external salt concentration, and concentration of fixed charges. Comparisons with previous experiments for an ionized acrylamide gel in mixed water–acetone solvents are made with good quantitative agreement for a monovalent salt (NaCl) but fair qualitative agreement for a divalent salt (MgCl2), using a simple set of parameters for both cases. The effective polymer–solvent interactions vary with the volume fraction of acetone in the mixed solvent, leading to either continuous or discontinuous volume transitions. The presence of divalent ions (Mg2+) in addition to monovalent ions in the external solution reduces the critical salt concentration for the discontinuous transition by several orders of magnitude. Moreover, a secondary continuous transition is predicted between two highly swollen states for the case of a divalent salt. The present model may be further extended to study volume phase transitions of polyelectrolyte gels in response to other stimuli such as temperature, pH and electrical field.

Study of silver mercaptide nanocluster formation in cystein-silver solution by atomistic molecular dynamics simulation

2010 ◽  
Vol 5 (3-4) ◽  
pp. 165-176 ◽  
Author(s):  
P. V. Komarov ◽  
V. G. Alekseev ◽  
S. D. Khizhnyak ◽  
M. M. Ovchinnikov ◽  
P. M. Pakhomov
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Silver Solution ◽  
Silver Mercaptide

SYMMODES: a software package for group-theoretical analysis of structural phase transitions

2003 ◽  
Vol 36 (3) ◽  
pp. 953-954 ◽  
Author(s):  
Cesar Capillas ◽  
Eli Kroumova ◽  
Mois I. Aroyo ◽  
J. Manuel Perez-Mato ◽  
Harold T. Stokes ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Theoretical Analysis ◽  
Software Package ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Group Theoretical Analysis

Electron Microscopy of Graphite Intercalation Compounds

1982 ◽  
Vol 40 ◽  
pp. 544-545
Author(s):  
G. Timp ◽  
L. Salamanca-Riba ◽  
L.W. Hobbs ◽  
G. Dresselhaus ◽  
M.S. Dresselhaus
Keyword(s):  
Electron Microscopy ◽  
Phase Transitions ◽  
Domain Wall ◽  
Intercalation Compounds ◽  
Lattice Plane ◽  
Wall Model ◽  
Graphite Intercalation Compounds ◽  
Fundamental Symmetry ◽  
Graphite Intercalation

Electron microscopy can be used to study structures and phase transitions occurring in graphite intercalations compounds. The fundamental symmetry in graphite intercalation compounds is the staging periodicity whereby each intercalate layer is separated by n graphite layers, n denoting the stage index. The currently accepted model for intercalation proposed by Herold and Daumas assumes that the sample contains equal amounts of intercalant between any two graphite layers and staged regions are confined to domains. Specifically, in a stage 2 compound, the Herold-Daumas domain wall model predicts a pleated lattice plane structure.

Quanitative aspects of electron diffraction using electron holography

1995 ◽  
Vol 53 ◽  
pp. 616-617
Author(s):  
E. Völkl ◽  
L.F. Allard ◽  
B. Frost ◽  
T.A. Nolan
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Software Package ◽  
Spatial Coherence ◽  
Electron Holography ◽  
Image Intensity ◽  
Interference Fringes ◽  
Complex Image ◽  
The Difference ◽  
Recorded Image

Off-axis electron holography has the well known ability to preserve the complex image wave within the final, recorded image. This final image described by I(x,y) = I(r) contains contributions from the image intensity of the elastically scattered electrons IeI (r) = |A(r) exp (iΦ(r)) |, the contributions from the inelastically scattered electrons IineI (r), and the complex image wave Ψ = A(r) exp(iΦ(r)) as:(1) I(r) = IeI (r) + Iinel (r) + μ A(r) cos(2π Δk r + Φ(r))where the constant μ describes the contrast of the interference fringes which are related to the spatial coherence of the electron beam, and Φk is the resulting vector of the difference of the wavefront vectors of the two overlaping beams. Using a software package like HoloWorks, the complex image wave Ψ can be extracted.

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