2,566 research outputs found
Superparamagnetic iron oxide nanoparticles regulate smooth muscle cell phenotype
Superparamagnetic iron oxide nanoparticles are used for an increasing range of biomedical applications, from imaging to mechanical actuation of cells and tissue. The aim of this study was to investigate the loading of smooth muscle cells with superparamagnetic iron oxide nanoparticles and to explore what effect this has on the phenotype of the cells. Adherent human smooth muscle cells were loaded with ∼17 pg of unconjugated, negatively charged, 50 nm superparamagnetic iron oxide nanoparticles (SPION). Clusters of the internalized SPION particles were held in discrete cytoplasmic vesicles. Internalized SPION did not cause any change in cell morphology, proliferation, metabolic activity, or staining pattern of actin and calponin, two of the muscle contractile proteins involved in force generation. However, internalized SPION inhibited the increased gene expression of actin and calponin normally observed when cells are incubated under differentiation conditions. The observed change in the control of gene expression of muscle contractile apparatus by SPION has not previously been described. This finding could offer novel approaches for regulating the phenotype of smooth muscle cells and warrants further investigation. This article is protected by copyright. All rights reserved
Assessment of the Social and Physical Characteristics of Obiagu Shanty Area in Enugu Metropolitan City, Nigeria
The persistent rise of the urban population and high housing rent has driven many to shanty towns. However, due to the increased population of the shanty towns, the social and physical characteristics of the towns have deteriorated. The study assessed the social and physical characteristics of Obiagu Shanty Area in Enugu Metropolitan City, Nigeria, with the purpose of establishing the extent of the rehabilitation and its impacts in the lives of the residents, as well as provides a better alternative. The data was obtained using a questionnaire survey. The statistical techniques employed to analyse the data are descriptive statistics (such as simple percentages, standard deviation and mean). The study, in general terms identified that the level of physical and social characteristics of Obiagu Shanty Area is highly negative. The study also reveals poor infrastructural amenities in the area. It demonstrates that the government is failing to fulfill its responsibilities in terms of urban development and infrastructure renewal. Furthermore, the study shows that private individuals and communities do not actively participate in urban regeneration and infrastructural renewal efforts in Obiagu Shanty Area. Therefore, the study recommends some retrofitting measures, such as the construction of modern houses with modern facilities and good sewage systems, the government partnering with private organisations/individuals or the community to assist in the remodeling of structures in the area, and constant sensitisation of residents by the government and NGOs on the negative health consequences of living in a dirty environment, among other things. Keywords: Shanty Area, Social Characteristics, Physical Characteristics, Metropolitan City, Retrofitting Measures, Urban Regeneration DOI: 10.7176/JEES/12-9-05 Publication date:September 30th 202
Micromagnetic simulations of interacting dipoles on a fcc lattice: Application to nanoparticle assemblies
Micromagnetic simulations are used to examine the effects of cubic and axial
anisotropy, magnetostatic interactions and temperature on M-H loops for a
collection of magnetic dipoles on fcc and sc lattices. We employ a simple model
of interacting dipoles that represent single-domain particles in an attempt to
explain recent experimental data on ordered arrays of magnetoferritin
nanoparticles that demonstrate the crucial role of interactions between
particles in a fcc lattice. Significant agreement between the simulation and
experimental results is achieved, and the impact of intra-particle degrees of
freedom and surface effects on thermal fluctuations are investigated.Comment: 10 pages, 9 figure
First-Order Transition to Incommensurate Phase with Broken Lattice Rotation Symmetry in Frustrated Heisenberg Model
We study a finite-temperature phase transition in the two-dimensional
classical Heisenberg model on a triangular lattice with a ferromagnetic
nearest-neighbor interaction and an antiferromagnetic
third-nearest-neighbor interaction using a Monte Carlo method. Apart from
a trivial degeneracy corresponding to O(3) spin rotations,the ground state for
has a threefold degeneracy corresponding to 120 degree lattice
rotations. We find that this model exhibits a first-order phase transition with
the breaking of the threefold symmetry when the interaction ratio is
.Comment: 4pages,5figure
Metric characterization of cluster dynamics on the Sierpinski gasket
We develop and implement an algorithm for the quantitative characterization
of cluster dynamics occurring on cellular automata defined on an arbitrary
structure. As a prototype for such systems we focus on the Ising model on a
finite Sierpsinski Gasket, which is known to possess a complex thermodynamic
behavior. Our algorithm requires the projection of evolving configurations into
an appropriate partition space, where an information-based metrics (Rohlin
distance) can be naturally defined and worked out in order to detect the
changing and the stable components of clusters. The analysis highlights the
existence of different temperature regimes according to the size and the rate
of change of clusters. Such regimes are, in turn, related to the correlation
length and the emerging "critical" fluctuations, in agreement with previous
thermodynamic analysis, hence providing a non-trivial geometric description of
the peculiar critical-like behavior exhibited by the system. Moreover, at high
temperatures, we highlight the existence of different time scales controlling
the evolution towards chaos.Comment: 20 pages, 8 figure
Monte Carlo Study of an Extended 3-State Potts Model on the Triangular Lattice
By introducing a chiral term into the Hamiltonian of the 3-state Potts model
on a triangular lattice additional symmetries are achieved between the
clockwise and anticlockwise states and the ferromagnetic state. This model is
investigated using Monte Carlo methods. We investigate the full phase diagram
and find evidence for a line tricritical points separating the ferromagnetic
and antiferromagnetic phases.Comment: 6 pages, 10 figure
Multifractal Behaviour of n-Simplex Lattice
We study the asymptotic behaviour of resistance scaling and fluctuation of
resistance that give rise to flicker noise in an {\em n}-simplex lattice. We
propose a simple method to calculate the resistance scaling and give a
closed-form formula to calculate the exponent, , associated with
resistance scaling, for any n. Using current cumulant method we calculate the
exact noise exponent for n-simplex lattices.Comment: Latex, 9 pages including one figur
Indentation Plastometry for Study of Anisotropy and Inhomogeneity in Maraging Steel Produced by Laser Powder Bed Fusion
This work concerns the use of profilometry-based indentation plastometry (PIP) to obtain mechanical property information for maraging steel samples produced via an additive manufacturing route (laser powder bed fusion). Bars are produced in both “horizontal” (all material close to the build plate) and “vertical” (progressively increasing distance from the build plate) configurations. Samples are mechanically tested in both as-built and age-hardened conditions. Stress–strain curves from uniaxial testing (tensile and compressive) are compared with those from PIP testing. Tensile test data suggest significant anisotropy, with the horizontal direction harder than the vertical direction. However, systematic compressive tests, allowing curves to be obtained for both build and transverse directions in various locations, indicate that there is no anisotropy anywhere in these materials. This is consistent with electron backscattered diffraction results, indicating that there is no significant texture in these materials. It is also consistent with the outcomes of PIP testing, which can detect anisotropy with high sensitivity. Furthermore, both PIP testing and compression testing results indicate that the changing growth conditions at different distances from the build plate can lead to strength variations. It seems likely that what has previously been interpreted as anisotropy in the tensile response is in fact due to inhomogeneity of this type
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