We study by means of the 2D Blume–Emery–Griffiths (BEG) spin-1 model, spin-crossover (SCO) and prussian blue analogs (PBAs) solids. In this model, the spin states, which can be high-spin (HS) or ...low-spin (LS), interact magnetically and elastically with their nearest neighbors. To account for the volume change, accompanying the spin transition phenomenon, all interactions through the lattice are assumed as temperature-dependent. In addition, the system is subject to a variable magnetic field lifting the degeneracy in the HS state. A stochastic cooperative dynamics of this BEG-like Hamiltonian, describing the equilibrium and nonequilibrium properties of ferromagnetic spin-crossover solids, is derived from the Glauber approach, with appropriate Arrhenius microscopic transition rates. The model generates under the magnetic field, sigmoidal relaxation and a hysteresis phenomenon of the HS fraction, as well as multistep behavior of the magnetization. These behaviors open the way to new route of multi-stable systems, desired in multi-byte electronics.
Graphic Abstract
Two dimension (2D) Blume–Emery–Griffiths (BEG) spin-1 model is used to investigate spin-crossover (SCO) and Prussian Blue Analogs (PBAs) solids. The model considered here allows the system to switch ...between two fundamental spin states named high-spin (HS) and low-spin (LS) states subsequent to the strength of magnetic and elastic interactions which acting on lattice nearest neighbors sites. These interactions are assumed as temperature-dependent due to the system volume changes accompanying with the spin transition phenomenon. In addition, SCO molecules are subject to a variable frequency of magnetic-field lifting the degeneracy in the HS state. A stochastic cooperative dynamics of this BEG-like Hamiltonian, describing the nonequilibrium properties of ferromagnetic SCO solids, is derived from the Glauber approach, with appropriate Arrhenius microscopic transition rates. At the vicinity of the thermal hysteresis loop of the free system (obtained with zero-magnetic field), investigations with variable oscillation frequency of the magnetic-field,
h
, demonstrated significant changes on the isothermal relaxation curves of the magnetization,
m
, and the high-spin fraction,
n
HS
, which fall down on dynamical equilibrium characterized by limiting cycles in the spaces
m
-
h
and
n
HS
-
h
. In addition, the clear evidence of dephasing between the responses of the two order parameters (
m
and
n
HS
) and the particular “butterfly” shape of the limiting cycles of the HS fraction, enforces the idea that the non-linear effects, propagating through the interaction parameters, are operating in this system. These behaviors demonstrate that radio-frequency magnetic field can be used in these SCO systems to achieve a reversible switch and control of both magnetization and HS fraction, even if the latter is partial. These results are in direct relation with the intrinsic static multi-stability of the system under static magnetic-field, which is enhanced/revealed by applying an oscillating magnetic-field.
Graphical abstract
The nonequilibrium properties of spin-crossover (SCO) solids are analyzed within 2D Blume–Emery–Griffiths (BEG) spin-1 model in which SCO molecules are subjected to a variable frequency of magnetic-field energy controlled by the parameter
λ
. Within the lattice configuration, to account for spin-phonon interactions, the strengths of magnetic and elastic interactions between nearest neighbors (
nn
) sites are temperature-dependent. At the vicinity of the thermal hysteresis loop of the free system, the isothermal relaxation curves of the magnetization
m
and the high-spin fraction,
n
HS
fall down on dynamical equilibrium characterized by limiting cycles which depend on the initial conditions in the spaces
m
-
h
and
n
HS
-
h
. The shift phase appears between the response of the two parameters (
m
and
n
HS
) which particular non-linear behaviors would seem to stem from the interactions propagating within the system through the interaction parameters. These behaviors revealed that radio-frequency magnetic-field can be used in these SCO systems to achieve a reversible switch and control of both magnetization and HS fraction.
Graphic abstract
Viral infection outcomes vary widely between individuals, ranging from mild symptoms to severe organ failure and death, and it is clear that host genetic factors play a role in this variability. Type ...I interferon (IFN) is a critical anti-viral cytokine, and we have previously noted differences in type I IFN levels between world populations.
In this study, we investigate the interrelationship between regional European genetic ancestry, type I IFN levels, and severe viral infection outcomes.
In cohorts of European ancestry lupus patients living in Europe, we noted higher IFN in the Northwestern populations as compared to Southeastern populations. In an independent cohort of European ancestry lupus patients from the United States with varying proportional regional European genetic admixture, we observed the same Northwest vs. Southeast European ancestry IFN gradient. We developed a model to predict type I IFN level based on regional European ancestry (AUC = 0.73, p = 6.1e-6). Examining large databases containing serious viral outcomes data, we found that lower predicted IFN in the corresponding European country was significantly correlated with increased viral infection fatality rate, including COVID-19, viral hepatitis, and HIV Correlation coefficients: -0.79 (p = 4e-2), -0.94 (p = 6e-3), and -0.96 (p = 8e-2) respectively.
This association between predicted type I IFN level and viral outcome severity suggests a potential causal relationship, as greater intrinsic type I IFN is beneficial in host defense against viruses. Genetic testing could provide insight into individual and population level risk of fatality due to viruses prior to infection, across a wide range of viral pathogens.
The transverse Ising model with bimodal random bond dilution and trimodal random longitudinal magnetic field was studied in terms of the effective-field theory (EFT) with correlations for a ...finite-cluster. The nearest-neighbor spins are assumed to be interacting randomly either ferromagnetically with probability
p
or the interaction between them are turned off with probability
(
1
-
p
)
. It is also assumed that half of the spins are under the influence of longitudinal magnetic field with equal probability t/2 along
z
-axis having the values of
+
H
and
-
H
while the other half of spins is free of
H
with probability
1
-
t
. The effects of changing the probabilities
p
and
t
, and the magnitudes of transverse and longitudinal magnetic fields for the magnetization components under temperature variations were examined in detail to obtain the possible phase diagrams of the model. It was obtained that the model exhibits both second- and first-order phase transitions, in addition to the tricritical points and reentrant behaviors for the first- and second-order phase transition temperature lines.
A two-dimensional Blume-Emery-Griffiths spin-1 model with spin-phonon interaction is introduced to investigate the thermodynamic properties of Prussian Blue Analogs and Spin-crossover materials. The ...quadrupolar interaction parameter is assumed to depend on the temperature in the form
K
=
α
k
B
T
while the crystal-field depends both on the ligand-field strength and the degeneracy ratio between high spin (HS) and low spin (LS) states as in some previous works. The model is solved by means of two statistical-mechanical methods: kinetic Monte Carlo simulations and corrective effective field theory calculations. Our calculations indicate that by tuning
α
, the spin-crossover transition changes to a sharp first order transition where the HS fraction,
n
HS
changes discontinuously. Second order transitions are observed in the presence of magnetic ordering when the nearest-neighbor coupling constant
J
exceeds some critical value
J
c
which depends on
α
and other model parameters. Below
J
c
, simple spin-transition occurs at an equilibrium temperature
T
eq
that is very sensitive to the values of the degenaracy ratio and the ligand-field. Competition between model parameters lead to interesting phase diagrams. Some of them are displayed for varying values of the coupling
J
and also in the specific case where
J
and
K
are of the same order of magnitude. Thermal hysteresis loops have been calculated by Monte Carlo simulations and also by using the self-consistent equations in the case of long-lived metastable states showing strong dependence on model parameters.
Background: Colorectal cancer (CRC) is common and often presents with advanced disease in Africa. Multivisceral resection (MVR) improves survival in locally advanced (T4b) CRC. The aim was to ...describe the management and outcomes of patients with clinical T4b CRC without metastatic disease who underwent MVR.Methods: A retrospective review of patients with T4 CRC who underwent MVR between January 2008 and December 2013.Results: Four hundred and ninety-four patients were included. Of the 158 with suspected T4 cancer, 44 had MVR, of which one was excluded due to metastases. The mean age was 64 years. The male to female ratio was 1:1. The most commonly resected extra-colorectal structure was the abdominal wall (21%). The median survival was 68 months (SD 13.9). The 5-year disease free (DFS) and overall survival (OS) were 46% and 55%, respectively. Survival of patients with colon and rectum cancer was similar. Intraoperative tumour spillage, vascular/perineural invasion, and anastomotic leakage were independent predictors of survival.Conclusion: Multivisceral resection of locally advanced (T4b) CRC is feasible in the African context. Complete resection improves survival and should be the goal.
The mean-field approximation based on the Gibbs-Bogoliubov inequality and Monte Carlo simulations based on the Metropolis method in the Blume–Emery–Griffiths model were used to successfully examine a ...hexagonal Ising nanowire with spin-1. It was found that the model displays fascinating phase diagrams in various planes of interest by using both methods. The investigation of magnetic hysteresis cycles also exhibits interesting properties. The model not only presents first- and second-order phase transition lines, but also the tricritical and isolated critical points, multi-compensation temperatures, and magnetic hysteresis behavior with one to eight cycles.
•The mean-field approximation based on the Gibbs-Bogoliubov inequality is applied.•The Monte Carlo simulations based on the Metropolis method is employed.•Spin-1 Blume–Emery–Griffiths model for hexagonal Ising nanowire is investigated.•First- and second-order transitions, tricritical and isolated critical points are found.•Multi-compensation and magnetic hysteresis with one to eight cycles are observed.
A cylindrical Ising nanotube that consists of 3/2 core spins surrounded by 5/2 shell spins is introduced and studied with Mean-Field approximation and Monte Carlo simulations in the presence of ...crystal and external magnetic fields. The effects of positive and negative interfacial coupling constants on the magnetic properties have been examined. The thermal behaviors of the order parameters and different types of macroscopic instabilities are presented. The model exhibits compensation points, first- and second-order phase transitions. Richer magnetic properties are obtained in the antiferromagnetic core–shell coupling case. In the presence of ferromagnetic interfacial coupling, the simulations sometimes generated long-lived metastable states. These states jumped to stable thermodynamic ones under thermal fluctuations via first-order phase transitions.
•Magnetic properties study of Ising nanotube with external magnetic field.•Mean-Field theory and Monte Carlo simulation methods used.•First- and second-order phase transitions specified in several phase diagrams.•Existence of compensation temperatures for appropriate values of model parameters.•Existence of magnetic hysteresis behaviors with multiple hysteresis cycles.
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