Abstract: Propagation of arbitrary amplitude nonlinear Alfven
waves has been investigated in low but finite β electron-positron-ion
plasma including full ion dynamics. Using Sagdeev pseudopotential
method an energy integral equation has been derived. The Sagdeev
potential has been calculated for different plasma parameters and it
has been shown that inclusion of ion parallel motion along the
magnetic field changes the nature of slow shear Alfven wave solitons
from dip type to hump type. The effects of positron concentration,
plasma-β and obliqueness of the wave propagation on the solitary
wave structure have also been examined.
Abstract: In recent years a new method of combination
treatment for cancer has been developed and studied that has led to
significant advancements in the field of cancer therapy. Hyperthermia
is a traditional therapy that, along with a creation of a medically
approved level of heat with the help of an alternating magnetic AC
current, results in the destruction of cancer cells by heat. This paper
gives details regarding the production of the spherical nanocomposite
PVA/γ-Fe2O3 in order to be used for medical purposes such as tumor
treatment by hyperthermia. To reach a suitable and evenly distributed
temperature, the nanocomposite with core-shell morphology and
spherical form within a 100 to 200 nanometer size was created using
phase separation emulsion, in which the magnetic nano-particles γ-
Fe2O3 with an average particle size of 20 nano-meters and with
different percentages of 0.2, 0.4, 0.5 and 0.6 were covered by
polyvinyl alcohol. The main concern in hyperthermia and heat
treatment is achieving desirable specific absorption rate (SAR) and
one of the most critical factors in SAR is particle size. In this project
all attempts has been done to reach minimal size and consequently
maximum SAR. The morphological analysis of the spherical
structure of the nanocomposite PVA/γ-Fe2O3 was achieved by SEM
analyses and the study of the chemical bonds created was made
possible by FTIR analysis. To investigate the manner of magnetic
nanocomposite particle size distribution a DLS experiment was
conducted. Moreover, to determine the magnetic behavior of the γ-
Fe2O3 particle and the nanocomposite PVA/γ-Fe2O3 in different
concentrations a VSM test was conducted. To sum up, creating
magnetic nanocomposites with a spherical morphology that would be
employed for drug loading opens doors to new approaches in
developing nanocomposites that provide efficient heat and a
controlled release of drug simultaneously inside the magnetic field,
which are among their positive characteristics that could significantly
improve the recovery process in patients.
Abstract: The effect of partially substitution of magnetic
impurity Fe for Cu to the magnetic and transport properties in
electron-doped superconducting cuprates of
Eu1.85+yCe0.15-yCu1-yFeyO4+α-δ (ECCFO) with y = 0, 0.010, 0.020, and
0.050 has been studied, in order to investigate the mechanism of
magnetic and transport properties of ECCFO in normal-state.
Magnetic properties are investigated by DC magnetic-susceptibility
measurements that carried out at low temperatures down to 2 K using a
standard SQUID magnetometer in a magnetic field of 5 Oe on field
cooling. Transport properties addressed to electron mobility, are
extracted from radius of electron localization calculated from
temperature dependence of resistivity. For y = 0, temperature
dependence of dc magnetic-susceptibility (χ) indicated the change of
magnetic behavior from paramagnetic to diamagnetic below 15 K.
Above 15 K, all samples show paramagnetic behavior with the values
of magnetic moment in every volume unit increased with increasing y.
Electron mobility decreased with increasing y.
Abstract: This paper deals with the theoretical and numerical
investigation of magneto hydrodynamic boundary layer flow of a
nanofluid past a wedge shaped wick in heat pipe used for the cooling
of electronic components and different type of machines. To
incorporate the effect of nanoparticle diameter, concentration of
nanoparticles in the pure fluid, nanothermal layer formed around the
nanoparticle and Brownian motion of nanoparticles etc., appropriate
models are used for the effective thermal and physical properties of
nanofluids. To model the rotation of nanoparticles inside the base
fluid, microfluidics theory is used. In this investigation ethylene
glycol (EG) based nanofluids, are taken into account. The non-linear
equations governing the flow and heat transfer are solved by using a
very effective particle swarm optimization technique along with
Runge-Kutta method. The values of heat transfer coefficient are
found for different parameters involved in the formulation viz.
nanoparticle concentration, nanoparticle size, magnetic field and
wedge angle etc. It is found that, the wedge angle, presence of
magnetic field, nanoparticle size and nanoparticle concentration etc.
have prominent effects on fluid flow and heat transfer characteristics
for the considered configuration.
Abstract: Exact solution of an unsteady MHD flow of elasticoviscous
fluid through a porous media in a tube of spherical cross
section under the influence of magnetic field and constant pressure
gradient has been obtained in this paper. Initially, the flow is
generated by a constant pressure gradient. After attaining the steady
state, the pressure gradient is suddenly withdrawn and the resulting
fluid motion in a tube of spherical cross section by taking into
account of the porosity factor and magnetic parameter of the
bounding surface is investigated. The problem is solved in two-stages
the first stage is a steady motion in tube under the influence of a
constant pressure gradient, the second stage concern with an unsteady
motion. The problem is solved employing separation of variables
technique. The results are expressed in terms of a non-dimensional
porosity parameter (K), magnetic parameter (m) and elasticoviscosity
parameter (β), which depends on the Non-Newtonian
coefficient. The flow parameters are found to be identical with that of
Newtonian case as elastic-viscosity parameter and magnetic
parameter tends to zero and porosity tends to infinity. It is seen that
the effect of elastico-viscosity parameter, porosity parameter and
magnetic parameter of the bounding surface has significant effect on
the velocity parameter.
Abstract: The number of persons with implanted cardiac
pacemakers (PM) has increased in Western countries. The aim of this
paper is to investigate the possible situations where persons with a
PM may be exposed to extremely low frequency (ELF) electric (EF)
and magnetic fields (MF) that may disturb their PM. Based on our
earlier studies, it is possible to find such high public exposure to EFs
only in some places near 400 kV power lines, where an EF may
disturb a PM in unipolar mode. Such EFs cannot be found near 110
kV power lines. Disturbing MFs can be found near welding
machines. However, we do not have measurement data from welding.
Based on literature and earlier studies at Tampere University of
Technology, it is difficult to find public EF or MF exposure that is
high enough to interfere with PMs.
Abstract: The objective of this work is to study the effect of two
key factors - external magnetic field and applied current density
during template-based electrodeposition of nickel nanowires using an
electrode distance of 20 mm. Morphology, length, crystallite size and
crystallographic characterization of the grown nickel nanowires at an
electrode distance of 20mm are presented. For this electrode distance
of 20 mm, these two key electrodeposition factors when coupled was
found to reduce crystallite size with a higher growth length and
preferred orientation of Ni crystals. These observed changes can be
inferred to be due to coupled interaction forces induced by the
intensity of applied electric field (current density) and external
magnetic field known as magnetohydrodynamic (MHD) effect during
the electrodeposition process.
Abstract: The convective heat and mass transfer in nanofluid
flow through a porous media due to a permeable stretching sheet with
magnetic field, viscous dissipation, chemical reaction and Soret
effects are numerically investigated. Two types of nanofluids, namely
Cu-water and Ag-water were studied. The governing boundary layer
equations are formulated and reduced to a set of ordinary differential
equations using similarity transformations and then solved
numerically using the Keller box method. Numerical results are
obtained for the skin friction coefficient, Nusselt number and
Sherwood number as well as for the velocity, temperature and
concentration profiles for selected values of the governing
parameters. Excellent validation of the present numerical results has
been achieved with the earlier linearly stretching sheet problems in
the literature.
Abstract: Theory of interpretation of electromagnetic fields studied in the electrical prospecting with direct current is mainly developed for the case of a horizontal surface observation. However in practice we often have to work in difficult terrain surface. Conducting interpretation without the influence of topography can cause non-existent anomalies on sections. This raises the problem of studying the impact of different shapes of ground surface relief on the results of electrical prospecting's research. This research examines the numerical solutions of the direct problem of electrical prospecting for two-dimensional and three-dimensional media, taking into account the terrain. The problem is solved using the method of integral equations. The density of secondary currents on the relief surface is obtained.
Abstract: Mechanical stress has a strong effect on the magnitude
of the Barkhausen-noise in structural steels. Because the
measurements are performed at the surface of the material, for a
sample sheet, the full effect can be described by a biaxial stress field.
The measured Barkhausen-noise is dependent on the orientation of
the exciting magnetic field relative to the axis of the stress tensor.
The sample inhomogenities including the residual stress also
modifies the angular dependence of the measured Barkhausen-noise.
We have developed a laboratory device with a cross like specimen
for bi-axial bending. The measuring head allowed performing
excitations in two orthogonal directions. We could excite the two
directions independently or simultaneously with different amplitudes.
The simultaneous excitation of the two coils could be performed in
phase or with a 90 degree phase shift. In principle this allows to
measure the Barkhausen-noise at an arbitrary direction without
moving the head, or to measure the Barkhausen-noise induced by a
rotating magnetic field if a linear superposition of the two fields can
be assumed.
Abstract: An analysis is carried out to investigate the effect of
magnetic field and heat source on the steady boundary layer flow and
heat transfer of a Casson nanofluid over a vertical cylinder stretching
exponentially along its radial direction. Using a similarity
transformation, the governing mathematical equations, with the
boundary conditions are reduced to a system of coupled, non –linear
ordinary differential equations. The resulting system is solved
numerically by the fourth order Runge – Kutta scheme with shooting
technique. The influence of various physical parameters such as
Reynolds number, Prandtl number, magnetic field, Brownian motion
parameter, thermophoresis parameter, Lewis number and the natural
convection parameter are presented graphically and discussed for non
– dimensional velocity, temperature and nanoparticle volume
fraction. Numerical data for the skin – friction coefficient, local
Nusselt number and the local Sherwood number have been tabulated
for various parametric conditions. It is found that the local Nusselt
number is a decreasing function of Brownian motion parameter Nb
and the thermophoresis parameter Nt.
Abstract: The Ising ferromagnet, consisting of magnetic spins, is
the simplest system showing phase transitions and critical phenomena
at finite temperatures. The Ising ferromagnet has played a central role
in our understanding of phase transitions and critical phenomena.
Also, the Ising ferromagnet explains the gas-liquid phase transitions
accurately. In particular, the Ising ferromagnet in a nonzero magnetic
field has been one of the most intriguing and outstanding unsolved
problems. We study analytically the partition function zeros in the
complex magnetic-field plane and the Yang-Lee edge singularity of
the infinite-range Ising ferromagnet in an external magnetic field.
In addition, we compare the Yang-Lee edge singularity of the
infinite-range Ising ferromagnet with that of the square-lattice Ising
ferromagnet in an external magnetic field.
Abstract: Liposome plays an important role in medical and
pharmaceutical science as e.g. nano scale drug carriers. Liposomes
are vesicles of varying size consisting of a spherical lipid bilayer and
an aqueous inner compartment. Magnet-driven liposome used for the
targeted delivery of drugs to organs and tissues. These liposome
preparations contain encapsulated drug components and finely
dispersed magnetic particles.
Liposomes are vesicles of varying size consisting of a spherical
lipid bilayer and an aqueous inner compartment that are generated in
vitro. These are useful in terms of biocompatibility, biodegradability,
and low toxicity, and can control biodistribution by changing the size,
lipid composition, and physical characteristics. Furthermore,
liposomes can entrap both hydrophobic and hydrophilic drugs and are
able to continuously release the entrapped substrate, thus being useful
drug carriers. Magnetic liposomes (MLs) are phospholipid vesicles
that encapsulate magneticor paramagnetic nanoparticles. They are
applied as contrast agents for magnetic resonance imaging (MRI).
The biological synthesis of nanoparticles using plant extracts plays
an important role in the field of nanotechnology. Green-synthesized
magnetite nanoparticles-protein hybrid has been produced by treating
Iron (III) / Iron (II) chloride with the leaf extract of Datura inoxia.
The phytochemicals present in the leaf extracts act as a reducing as
well stabilizing agents preventing agglomeration, which include
flavonoids, phenolic compounds, cardiac glycosides, proteins and
sugars.
The magnetite nanoparticles-protein hybrid has been trapped
inside the aqueous core of the liposome prepared by reversed phase
evaporation (REV) method using oleic and linoleic acid which has
been shown to be driven under magnetic field confirming the
formation magnetic liposome (ML). Chemical characterization of
stealth magnetic liposome has been performed by breaking the
liposome and release of magnetic nanoparticles. The presence iron
has been confirmed by colour complex formation with KSCN and
UV-Vis study using spectrophotometer Cary 60, Agilent.
This magnet driven liposome using nanoparticles-protein hybrid
can be a smart vesicles for the targeted drug delivery.
Abstract: Exact solution of an unsteady flow of elastico-viscous
electrically conducting fluid through a porous media in a tube of
elliptical cross section under the influence of constant pressure
gradient and magnetic field has been obtained in this paper. Initially,
the flow is generated by a constant pressure gradient. After attaining
the steady state, the pressure gradient is suddenly withdrawn and the
resulting fluid motion in a tube of elliptical cross section by taking
into account of the transverse magnetic field and porosity factor of
the bounding surface is investigated. The problem is solved in twostages
the first stage is a steady motion in tube under the influence of
a constant pressure gradient, the second stage concern with an
unsteady motion. The problem is solved employing separation of
variables technique. The results are expressed in terms of a nondimensional
porosity parameter (K), magnetic parameter (m) and
elastico-viscosity parameter (β), which depends on the Non-
Newtonian coefficient. The flow parameters are found to be identical
with that of Newtonian case as elastic-viscosity parameter and
magnetic parameter tends to zero and porosity tends to infinity. It is
seen that the effect of elastico-viscosity parameter, magnetic
parameter and the porosity parameter of the bounding surface has
significant effect on the velocity parameter.
Abstract: This paper considers the characterization of a complex
electromagnetic environment due to multiple sources of
electromagnetic radiation as a five-dimensional surface which can be
described by a set of several surface sections including: instant EM
field intensity distribution maps at a given frequency and altitude,
instantaneous spectrum at a given location in space and the time
evolution of the electromagnetic field spectrum at a given point in
space. This characterization if done over time can enable the
exposure levels of Radio Frequency Radiation at every point in the
analysis area to be determined and results interpreted based on
comparison of the determined RFR exposure level with the safe
guidelines for general public exposure given by recognized body
such as the International commission on non-ionizing radiation
protection (ICNIRP), Institute of Electrical and Electronic Engineers
(IEEE), the National Radiation Protection Authority (NRPA).
Abstract: One- and two-dimensional carbon nanostructures with
sp2 hybridization of carbon atoms (single walled carbon nanotubes
and graphene) are promising materials in future electronic and
spintronics devices due to specific character of their electronic
structure. In this paper we present a comparative study of graphene
and single-wall carbon nanotubes by Raman spectro-microscopy in
strong magnetic field. This unique method allows to study changes in
electronic band structure of the two types of carbon nanostructures
induced by a strong magnetic field.
Abstract: The use of permanent magnets (PM) is increasing in
permanent magnet synchronous machines (PMSM) to fulfill the
requirements of high efficiency machines in modern industry. PMSM
are widely used in industrial applications, wind power plants and the
automotive industry. Since PMSM are used in different
environmental conditions, the long-term effect of NdFeB-based
magnets at high temperatures and their corrosion behavior have to be
studied due to the irreversible loss of magnetic properties.
In this paper, the effect of magnetic properties due to corrosion
and increasing temperature in a climatic chamber has been presented.
The magnetic moment and magnetic field of the magnets were
studied experimentally.
Abstract: A theoretical study has been presented to describe the boundary layer flow and heat transfer on an exponentially shrinking sheet with a variable wall temperature and suction, in the presence of magnetic field. The governing nonlinear partial differential equations are converted into ordinary differential equations by similarity transformation, which are then solved numerically using the shooting method. Results for the skin friction coefficient, local Nusselt number, velocity profiles as well as temperature profiles are presented through graphs and tables for several sets of values of the parameters. The effects of the governing parameters on the flow and heat transfer characteristics are thoroughly examined.
Abstract: Wireless communications have been expanded very fast in recent decades. This technology relies on an extensive network of base stations and antennas, using radio frequency signals to transmit information. Devices that use wireless communication, while offering various services, basically act as sources of non-ionizing electromagnetic fields (EMF). Such devices are permanently present in human vicinity and almost constantly radiate, causing EMF pollution of the environment. This fact has initiated development of modern systems for observation of the EMF pollution, as well as for risk assessment. This paper presents the Serbian electromagnetic field monitoring network – SEMONT, designed for automated, remote and continuous broadband monitoring of EMF in the environment. Measurement results of the SEMONT monitoring at one of the test locations, within the main campus of the University of Novi Sad, are presented and discussed, along with corresponding exposure assessment of the general population, regarding the Serbian legislation.
Abstract: We offer a new technique for research of stability of current sheaths in space plasma taking into account the effect of polarization. At the beginning, the found perturbation of the distribution function is used for calculation of the dielectric permeability tensor, which simulates inhomogeneous medium of a current sheath. Further, we in the usual manner solve the system of Maxwell's equations closed with the material equation. The amplitudes of Fourier perturbations are considered to be exponentially decaying through the current sheath thickness. The dispersion equation follows from the nontrivial solution requirement for perturbations of the electromagnetic field. The resulting dispersion equation allows one to study the temporal and spatial characteristics of instability modes of the current sheath (within the limits of the proposed model) over a wide frequency range, including low frequencies.