Search results for: magnetic microsphere

Authors: Ashkan Javadzadegan, Aitak Javadzadegan, Babak Fakhim

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One of possible ways to retard movement of fluid is through applying an external magnetic field. In this regard, this study is focused on the effect of a uniform transverse magnetic field on fluid flow behavior inside a channel with a local symmetric constriction. Also, Ellis Non-Newtonian model is implemented to address the effects of shear-dependent viscosity. According to the results, the flow separation downstream of the constriction can be controlled by applying an external magnetic field and/or manipulating the shear-thinning degree of fluid. It is also demonstrated that pressure drop increases by an increase in the strength of the magnetic field.

Keywords: magnetic field, non-Newtonian, separation, shear thinning

Procedia PDF Downloads 400

Authors: Emilia Olivos, R. Arroyave, A. Vargas-Calderon, J. E. Dominguez-Herrera

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More efficient cooling systems are needed to reduce building energy consumption and environmental impact. At present researchers focus mainly on environmentally-friendly magnetic materials and the potential application in cooling devices. The magnetic materials presented in this project belong to a group known as Heusler alloys. These compounds are characterized by a strong coupling between their structure and magnetic properties. Usually, a change in one of them can alter the other, which implies changes in other electronic or structural properties, such as, shape magnetic memory response or the magnetocaloric effect. Those properties and its dependence with external fields make these materials interesting, both from a fundamental point of view, as well as on their different possible applications. In this work, first principles and Monte Carlo simulations have been used to calculate exchange couplings and magnetic properties as a function of an applied magnetic field on Heusler alloys. As a result, we found a large dependence of the magnetic susceptibility, entropy and heat capacity, indicating that the magnetic field can be used in experiments to trigger particular magnetic properties in materials, which are necessary to develop solid-state refrigeration devices.

Keywords: ferromagnetic materials, magnetocaloric effect, materials design, solid state refrigeration

Procedia PDF Downloads 174

Authors: J. H. Kim, S. Y. Park, K. M. Lim, S. K. Hyun

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The effect of sintering temperature on the magnetic and mechanical properties of Nd-Fe-B sintered magnets has been investigated in this study. The sintering temperature changed from 950°C to 1120°C. While remanence and hardness of the magnets increased with increasing sintering temperature, the coercivity first increased, and then decreased. The optimum magnetic and mechanical properties of the magnets were obtained at the sintering temperature of 1050°C. In order to clarify the reason for the variation on magnetic and mechanical properties of the magnets, we systematically analyzed the microstructure.

Keywords: magnetic and mechanical property, microstructure, permanent magnets, sintered Nd-Fe-B magnet

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Authors: M. R. Phadatare, J. V. Meshram, S. H. Pawar

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Conversion of electromagnetic energy into heat by nanoparticles (NPs) has the potential to be a powerful, non-invasive technique for biomedical applications such as magnetic fluid hyperthermia, drug release, disease treatment and remote control of single cell functions, but poor conversion efficiencies have hindered practical applications so far. In this paper, an attempt has been made to increase the efficiency of magnetic, thermal induction by NPs. To increase the efficiency of magnetic, thermal induction by NPs, one can take advantage of the exchange coupling between a magnetically hard core and magnetically soft shell to tune the magnetic properties of the NP and maximize the specific absorption rate, which is the gauge of conversion efficiency. In order to examine the tunability of magnetocrystalline anisotropy and its magnetic heating power, a representative magnetically hard material (CoFe₂O₄) has been coupled to a soft material (Ni₀.₅Zn₀.₅Fe₂O₄). The synthesized NPs show specific absorption rates that are of an order of magnitude larger than the conventional one.

Keywords: magnetic nanoparticles, surface functionalization of magnetic nanoparticles, magnetic fluid hyperthermia, specific absorption rate

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Authors: F. Abbas Pour Khotbehsara, B. Salehpour, A. Kianvash

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Many industrial materials like magnets need to be tested for the radiation environment expected at linear colliders (LC) where the accelerator and detectors will be subjected to large influences of beta, neutron and gamma’s over their life Gamma irradiation of the permanent sample magnets using a 60Co source was investigated up to an absorbed dose of 700Mrad shows a negligible effect on some magnetic properties of Nd-Fe-B. In this work, it has been tried to investigate the change of some important properties of Barium hexa ferrite. Results showed little decreases of magnetic properties at doses rang of 0.5 to 2.5 Mrad. But at the gamma irradiation dose up to 10 Mrad it is showed a few increase of properties. Also study of gamma irradiation of Nd-Fe-B showed considerably increase of magnetic properties.

Keywords: gamma ray irradiation, hard ferrite, magnetic coefficient, magnetic material, radiation dose

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Authors: Po-Chin Liang, Yung-Chu Chen, Chi-Feng Chiang, Yun-Ping Lin, Wen-Yuan Hsieh, Win-Li Lin

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The aim of this study was to develop super paramagnetic iron oxide (SPIO) nano-particles comprised of a magnetic Fe3O4 core and a shell of aqueous stable self-doped polyethylene glycol (PEG) with a high loading of doxorubicin (SPIO-PEG-D) for tumor theranostics. The in-vivo MRI study showed that there was a stronger T2-weighted signal enhancement for the group under a magnetic field, and hence it indicated that this group had a better accumulation of SPIO-PEG than the group without a magnetic field. In the anticancer evaluation of SPIO-PEG-D, the group with a magnetic field displayed a significantly smaller tumor size than the group without. The overall results show that SPIO-PEG-D nanoparticles have the potential for the application of MRI/monitoring chemotherapy and the therapy can be locally enhanced by applying an external magnetic field.

Keywords: super paramagnetic iron oxide nano particles, doxorubicin, chemotherapy, MRI, magnetic fields

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Authors: Navneet Kaur, S. D. Tiwari

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Superparamagnetism is an interesting phenomenon and observed in small particles of magnetic materials. It arises due to a reduction in particle size. In the superparamagnetic state, as the thermal energy overcomes magnetic anisotropy energy, the magnetic moment vector of particles flip their magnetization direction between states of minimum energy. Superparamagnetic nanoparticles have been attracting the researchers due to many applications such as information storage, magnetic resonance imaging, biomedical applications, and sensors. For information storage, thermal fluctuations lead to loss of data. So that nanoparticles should have high blocking temperature. And to achieve this, nanoparticles should have a higher magnetic moment and magnetic anisotropy constant. In this work, the magnetic anisotropy constant of the antiferromagnetic nanoparticles system is determined. Magnetic studies on nanoparticles of NiO (nickel oxide) are reported well. This antiferromagnetic nanoparticle system has high blocking temperature and magnetic anisotropy constant of order 105 J/m3. The magnetic study of NiO nanoparticles in the superparamagnetic region is presented. NiO particles of two different sizes, i.e., 6 and 8 nm, are synthesized using the chemical route. These particles are characterized by an x-ray diffractometer, transmission electron microscope, and superconducting quantum interference device magnetometry. The magnetization vs. applied magnetic field and temperature data for both samples confirm their superparamagnetic nature. The blocking temperature for 6 and 8 nm particles is found to be 200 and 172 K, respectively. Magnetization vs. applied magnetic field data of NiO is fitted to an appropriate magnetic expression using a non-linear least square fit method. The role of particle size distribution and magnetic anisotropy is taken in to account in magnetization expression. The source code is written in Python programming language. This fitting provides us the magnetic anisotropy constant for NiO and other magnetic fit parameters. The particle size distribution estimated matches well with the transmission electron micrograph. The value of magnetic anisotropy constants for 6 and 8 nm particles is found to be 1.42 X 105 and 1.20 X 105 J/m3, respectively. The obtained magnetic fit parameters are verified using the Neel model. It is concluded that the effect of magnetic anisotropy should not be ignored while studying the magnetization process of nanoparticles.

Keywords: anisotropy, superparamagnetic, nanoparticle, magnetization

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Authors: Mabrak Samir

Abstract:

The motor performance created by permanent magnetic in a slotless air-gap of a surface mounted permanent-magnet synchronous motor with non magnetic rotor and either sinusoidal or mixed (quasi-Halbatch) magnetization is presented in this paper using polar coordinates. The analysis works for both internal and external rotor motor topologies, The effect of stator slots is introduced by modulating the magnetic field distribution in the slotless stator by the complex relative air-gap permeance, calculated from the conformal transformation of the slot geometry. We compare predicted results of flux density distribution and cogging torque with those obtained by finite-element analysis.

Keywords: air-cored, cogging torque, finite element magnetic field, permanent-magnet

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Authors: Anurag Gaur Nidhi

Abstract:

Targeted drug delivery is a method of delivering medication to a patient in a manner that increases the concentration of the medication in some parts of the body relative to others. Targeted drug delivery seeks to concentrate the medication in the tissues of interest while reducing the relative concentration of the medication in the remaining tissues. This improves efficacy of the while reducing side effects. In the present work, we investigate the effect of magnetic field, flow rate and particle concentration on the capturing of magnetic particles transported in a stent implanted fluidic channel. Iron oxide magnetic nanoparticles (Fe3O4) nanoparticles were synthesized via co-precipitation method. The synthesized Fe3O4 nanoparticles were added in the de-ionized (DI) water to prepare the Fe3O4 magnetic particle suspended fluid. This fluid is transported in a cylindrical tube of diameter 8 mm with help of a peristaltic pump at different flow rate (25-40 ml/min). A ferromagnetic coil of SS 430 has been implanted inside the cylindrical tube to enhance the capturing of magnetic nanoparticles under magnetic field. The capturing of magnetic nanoparticles was observed at different magnetic magnetic field, flow rate and particle concentration. It is observed that capture efficiency increases from 47-67 % at magnetic field 2-5kG, respectively at particle concentration 0.6 mg/ml and at flow rate 30 ml/min. However, the capture efficiency decreases from 65 to 44 % by increasing the flow rate from 25 to 40 ml/min, respectively. Furthermore, it is observed that capture efficiency increases from 51 to 67 % by increasing the particle concentration from 0.3 to 0.6 mg/ml, respectively.

Keywords: capture efficiency, implant assisted-Magnetic drug targeting (IA-MDT), magnetic nanoparticles, In-vitro study

Procedia PDF Downloads 277

Authors: A. Selmi, A. Bettaibi, H. Rahmouni, R. M’nassri, N. Chniba Boudjada, A. Chiekhrouhou, K. Khirouni

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Investigation of magnetic and magnetocaloric properties of Pr₀.₇Ca₀.₃Mn₀.₉M₀.₁O₃ perovskite manganites (M=Cr and Ni) has been carried out. Our compounds were prepared by the conventional solid-state reaction method at high temperatures. Rietveld refinement of X-ray diffraction pattern using FULLPROF method shows that all compounds adopt the orthorhombic structure with Pnma space group. The partial substitution of Mn-site drives the system from charge order state to ferromagnetic one with a Curie temperature T𝒸=150K, 118k and 116K for M=Cr and Ni, respectively. Magnetization measurements versus temperature in a magnetic applied field of 0.05T show that all our samples exhibit a paramagnetic–ferromagnetic transition with decreasing temperature. From M(H) isotherms, we have deduced the magnetic entropy change, which present maximum values of 2.37 J/kg.K and 2.94 J/kg.K, in a magnetic field change of 5T for M=Cr and Ni, respectively.

Keywords: manganites, magnetocaloric, magnetic, refrigeration

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Authors: A. Zitouni, S. Bentata, B. Bouadjemi, T. Lantri, W. Benstaali, A. Zoubir, S. Cherid, A. Sefir

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The structural, electronic, and magnetic properties of transition metal Co and Mn doped zinc-blende semiconductor CdTe were calculated using the density functional theory (DFT) with both generalized gradient approximation (GGA). We have analyzed the structural parameters, charge and spin densities, total and partial densities of states. We find that the Co and Mn doped zinc blende CdTe show half-metallic behavior with a total magnetic moment of 6.0 and 10.0 µB, respectively.The results obtained, make the Co and Mn doped CdTe a promising candidate for application in spintronics.

Keywords: first-principles, half-metallic, diluted magnetic semiconductor, magnetic moment

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Authors: Sabit Horoz, Ahmet Ekicibil, Omer Sahin, M. Akyol

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In this study, CdZnS and Ni-doped CdZnS quantum dots(QDs) were prepared by the wet-chemical method at room temperature using mercaptoethanol as a capping agent. The structural and magnetic properties of the CdZnS and CdZnS doped with different concentrations of Ni QDs were examined by XRD and magnetic susceptibility measurements, respectively. The average particles size of cubic QDs obtained by full-width half maxima (FWHM) analysis, increases with increasing doping concentrations. The investigation of the magnetic properties showed that the Ni-doped samples exhibit signs of ferromagnetism, on the other hand, un-doped CdZnS is diamagnetic.

Keywords: un-doped and Ni doped CdZnS Quantum Dots (QDs), co-precipitation method, structural and optical properties of QDs, diluted magnetic semiconductor materials (DMSMs)

Procedia PDF Downloads 263

Authors: Moulay Youssef El Hafidi

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In this research, an enhanced room-temperature magnetic refrigerator based on nanofluid, consisting of permanent magnets as a magnetism source, gadolinium as magnetocaloric material, water as base liquid, and carbon nanotubes (CNT) as nanoparticles, has been designed. The magnetic field is supplied by NdFeB permanent magnets and is about 1.3 Tesla. Two similar heat exchangers are employed to absorb and expel heat. The cycle performance of this self-designed device is analyzed theoretically. The results provide useful data for future optimization of room-temperature magnetic refrigeration using nanofluids.

Keywords: magnetic cooling, nanofluid, gadolinium, permanent magnets, heat exchange

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Authors: Shashi Sharma, V. K. Katiyar, Uaday Singh

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The ability to manipulate magnetic particles in fluid flows by means of inhomogeneous magnetic fields is used in a wide range of biomedical applications including magnetic drug targeting (MDT). In MDT, magnetic carrier particles bounded with drug molecules are injected into the vascular system up-stream from the malignant tissue and attracted or retained at the specific region in the body with the help of an external magnetic field. Although the concept of MDT has been around for many years, however, wide spread acceptance of the technique is still looming despite the fact that it has shown some promise in both in vivo and clinical studies. This is because traditional MDT has some inherent limitations. Typically, the magnetic force is not very strong and it is also very short ranged. Since the magnetic force must overcome rather large hydrodynamic forces in the body, MDT applications have been limited to sites located close to the surface of the skin. Even in this most favorable situation, studies have shown that it is difficult to collect appreciable amounts of the MDCPs at the target site. To overcome these limitations of the traditional MDT approach, Ritter and co-workers reported the implant assisted magnetic drug targeting (IA-MDT). In IA-MDT, the magnetic implants are placed strategically at the target site to greatly and locally increase the magnetic force on MDCPs and help to attract and retain the MDCPs at the targeted region. In the present work, we develop a mathematical model to study the capturing of magnetic nanoparticles flowing in a fluid in an implant assisted cylindrical channel under the magnetic field. A coil of ferromagnetic SS 430 has been implanted inside the cylindrical channel to enhance the capturing of magnetic nanoparticles under the magnetic field. The dominant magnetic and drag forces, which significantly affect the capturing of nanoparticles, are incorporated in the model. It is observed through model results that capture efficiency increases from 23 to 51 % as we increase the magnetic field from 0.1 to 0.5 T, respectively. The increase in capture efficiency by increase in magnetic field is because as the magnetic field increases, the magnetization force, which is attractive in nature and responsible to attract or capture the magnetic particles, increases and results the capturing of large number of magnetic particles due to high strength of attractive magnetic force.

Keywords: capture efficiency, implant assisted-magnetic drug targeting (IA-MDT), magnetic nanoparticles, modelling

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Authors: Chunduru Amareswara Prasad

Abstract:

The main aim of this proposal it to reveal the secrets of the universe by accelerating neutrons. The proposal idea in its abridged version speaks about the possibility of making neutrons accelerate with help of thermal energy and magnetic energy under controlled conditions. Which is helpful in revealing the hidden secrets of the universe namely dark energy and in finding properties of Higgs boson. The paper mainly speaks about accelerating neutrons to near velocity of light in a LINAC, using magnetic energy by magnetic pressurizers. The center of mass energy of two colliding neutron beams is 94 GeV (~0.5c) can be achieved using this method. The conventional ways to accelerate neutrons has some constraints in accelerating them electromagnetically as they need to be separated from the Tritium or Deuterium nuclei. This magnetic gradient method provides efficient and simple way to accelerate neutrons.

Keywords: neutron, acceleration, thermal energy, magnetic energy, Higgs boson

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Authors: Arnab Roy, P. S. Anil Kumar

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Hall bar magnetic field sensors based on planar hall effect were fabricated from permalloy (Ni¬80Fe20) thin films grown by pulsed laser ablation. As large as 400% planar Hall voltage change was observed for a magnetic field sweep within ±4 Oe, a value comparable with present day TMR sensors at room temperature. A very large planar Hall sensitivity of 1200 Ω/T was measured close to switching fields, which was not obtained so far apart from 2DEG Hall sensors. In summary, a highly sensitive low magnetic field sensor has been constructed which has the added advantage of simple architecture, good signal to noise ratio and robustness.

Keywords: planar hall effect, permalloy, NiFe, pulsed laser ablation, low magnetic field sensor, high sensitivity magnetic field sensor

Procedia PDF Downloads 489

Authors: Young-Kwan Choi, Han-Sang Jeong, Yeon-Ho Ok, Jae-Ho Choi

Abstract:

The purpose of this study is to verify validity of design by testing output of induction generator through finite element analysis before manufacture of induction generator designed. Characteristics in the operating domain of induction generator can be understood through analysis of magnetic field according to load (rotational speed) of induction generator. Characteristics of induction generator such as induced voltage, current, torque, magnetic flux density (magnetic flux saturation), and loss can be predicted by analysis of magnetic field.

Keywords: electromagnetic analysis, induction generator, small hydro power generator, small francis turbine generator

Procedia PDF Downloads 1435

Authors: B. Ghebouli, M. A. Ghebouli, H. Choutri, M. Fatmi, L. Louail

Abstract:

The structural, elastic, electronic and magnetic properties of the diluted magnetic semiconductors MnxCa1-xS in the rock-salt phase have been investigated using first-principles calculations. Features such as lattice constant, bulk modulus, elastic constants, spin-polarized band structure, total and local densities of states have been computed. We predict the values of the exchange constants and the band edge spin splitting of the valence and conduction bands. The hybridization between S-3p and Mn-3d produces small local magnetic moment on the nonmagnetic Ca and S sites. The ferromagnetism is induced due to the exchange splitting of S-3p and Mn-3d hybridized bands. The total magnetic moment per Mn of MnxCa1-xS is 4.4µB and is independent of the Mn concentration. The unfilled Mn -3d levels reduce the local magnetic moment of Mn from its free space charge value of 5µB to 4.4µB due to 3p–3d hybridization.

Keywords: semiconductors, Ab initio calculations, band-structure, magnetic properties

Procedia PDF Downloads 324

Authors: Wei Zheng, Mao Ji, Zhe Hou, Meng Huang, Bo Qi

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The transformer is the key equipment of the power system. Winding deformation is one of the main transformer defects, and timely and effective detection of the transformer winding deformation can ensure the safe and stable operation of the transformer to the maximum extent. When winding deformation occurs, the size, shape and spatial position of the winding will change, which directly leads to the change of magnetic flux leakage distribution. Therefore, it is promising to study the online detection method of the transformer winding deformation based on magnetic flux leakage characteristics, in which the key step is to study the optimal placement method of magnetic flux leakage sensors inside the transformer. In this paper, a simulation model of the transformer winding deformation is established to obtain the internal magnetic flux leakage distribution of the transformer under normal operation and different winding deformation conditions, and the law of change of magnetic flux leakage distribution due to winding deformation is analyzed. The results show that different winding deformation leads to different characteristics of the magnetic flux leakage distribution. On this basis, an optimized placement of magnetic flux leakage sensors inside the transformer is proposed to provide a basis for the online detection method of transformer winding deformation based on the magnetic flux leakage characteristics.

Keywords: magnetic flux leakage, sensor placement method, transformer, winding deformation

Procedia PDF Downloads 153

Authors: Saurabh Basu, Sudin Ganguly

Abstract:

Conductance in graphene nanoribbons (GNR) in presence of magnetic (for example, Iron) and non-magnetic (for example, Gold) adatoms are explored theoretically within a Kane-Mele model for their possible spintronic applications and topologically non-trivial properties. In our work, we have considered the magnetic adatoms to induce a Rashba spin-orbit coupling (RSOC) and an exchange bias field, while the non-magnetic ones induce an RSOC and an intrinsic spin-orbit (SO) coupling. Even though RSOC is present in both, they, however, represent very different physical situations, where the magnetic adatoms do not preserve the time reversal symmetry, while the non-magnetic case does. This has important implications on the topological properties. For example, the non-magnetic adatoms, for moderately strong values of SO, the GNR denotes a quantum spin Hall insulator as evident from a 2e²/h plateau in the longitudinal conductance and presence of distinct conducting edge states with an insulating bulk. Since the edge states are protected by time reversal symmetry, the magnetic adatoms in GNR yield trivial insulators and do not possess any non-trivial topological property. However, they have greater utility than the non-magnetic adatoms from the point of view of spintronic applications. Owing to the broken spatial symmetry induced by the presence of adatoms of either type, all the x, y and z components of the spin-polarized conductance become non-zero (only the y-component survives in pristine Graphene owing to a mirror symmetry present there) and hence become suitable for spintronic applications. However, the values of the spin polarized conductances are at least two orders of magnitude larger in the case of magnetic adatoms than their non-magnetic counterpart, thereby ensuring more efficient spintronic applications. Further the applications are tunable by altering the adatom densities.

Keywords: magnetic and non-magnetic adatoms, quantum spin hall phase, spintronic applications, spin polarized conductance, time reversal symmetry

Procedia PDF Downloads 259

Authors: M. Ibrir, S. Berri, S. Lakel, D. Maouche And Y. Medkour

Abstract:

We have performed first-principle calculations of the structural, electronic and magnetic properties of KFeF3, KCoF3, KMnF3, KVF3, using full-potential linearized augmented plane-wave (FP-LAPW) scheme within GGA. Features such as the lattice constant, bulk modulus and its pressure derivative are reported. Also, we have presented our results of the band structure and the density of states. The magnetic moments of KFeF3, KCoF3, KMnF3, KVF3 compounds are in most came from the exchange-splitting of X-3d orbital.

Keywords: Ab initio calculations, electronic structure, magnetic materials

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Authors: Chaoyan Huang, Hongxia Zheng

Abstract:

For deep space exploration and long duration interplanetary manned missions, protection of astronauts from cosmic radiation is an unavoidable problem. However, passive shielding can be little effective for protecting particles which energies are greater than 1GeV/nucleon. In this study, active magnetic protection method is adopted. Taking into account the structure and size of the end-cap, eight shielding magnetic field configurations are designed based on the Hoffman configuration. The shielding effect of shielding magnetic field structure, intensity B and thickness L on H particles with 2GeV energy is compared by test particle simulation. The result shows that the shielding effect is better with the linear type magnetic field structure in the end-cap region. Furthermore, two magnetic field configurations with better shielding effect are investigated through H and He galactic cosmic spectra. And the shielding effect of the linear type configuration adopted in the barrel and end-cap regions is best.

Keywords: galactic cosmic rays, active protection, shielding magnetic field configuration, shielding effect

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Authors: J. P. Borah, R. D. Raland

Abstract:

Hyperthermia is one of many techniques used destroys cancerous cell. It uses the physical methods to heat certain organ or tissue delivering an adequate temperature in an appropriate period of time, to the entire tumor volume for achieving optimal therapeutic results. Magnetic Metal ferrites nanoparticles (MFe₂O₄ where M = Mn, Zn, Ni, Co, Mg, etc.) are one of the most potential candidates for hyperthermia due to their tunability, biocompatibility, chemical stability and notable ability to mediate high rate of heat induction. However, to obtain the desirable properties for these applications, it is important to optimize their chemical composition, structure and magnetic properties. These properties are mainly sensitive to cation distribution of tetrahedral and octahedral sites. Among the ferrites, zinc ferrite (ZnFe₂O₄) and Manganese ferrite ((MnFe₂O₄) is one of a strong candidate for hyperthermia application because Mn and zinc have a non-magnetic cation and therefore the magnetic property is determined only by the cation distribution of iron, which provides a better platform to manipulate or tailor the properties. In this talk, influence of doping and surfactant towards cation re-distribution leading to an enhancement of magnetic properties of ferrite nanoparticles will be demonstrated. The efficiency of heat generation in association with the enhanced magnetic property is also well discussed in this talk.

Keywords: magnetic nanoparticle, hyperthermia, x-ray diffraction, TEM study

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Authors: Siva Kumar Reddy, Anwesha Mukherjee, Abha Misra

Abstract:

Excellent energy absorption capability in carbon nanotubes (CNT) is shown in their bulk structure that behaves like super compressible foam. Furthermore, a tunable mechanical behavior of CNT foam is achieved using several methods like changing the concentration of precursors, polymer impregnation, non covalent functionalization of CNT microstructure etc. Influence of magnetic field on compressive behavior of magnetic CNT demonstrated an enhanced peak stress and energy absorption capability, which does not require any surface and structural modification of the foam. This presentation discusses the mechanical behavior of micro porous CNT foam that is impregnated in magnetic field responsive fluid. Magnetic particles are dispersed in a nonmagnetic fluid so that alignment of both particles and CNT could play a crucial role in controlling the stiffness of the overall structure. It is revealed that the compressive behavior of CNT foam critically depends on the fluid viscosity as well as magnetic field intensity. Both peak Stress and energy absorption in CNT foam followed a power law behavior with the increase in the magnetic field intensity. However, in the absence of magnetic field, both peak stress and energy absorption capability of CNT foam presented a linear dependence on the fluid viscosity. Hence, this work demonstrates the role magnetic filed in controlling the mechanical behavior of the foams prepared at nanoscale.

Keywords: carbon nanotubes, magnetic field, energy absorption capability and viscosity

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Authors: A. Ikusika, O. I. Poppola

Abstract:

This study was carried out to delineate possible structures that may favour the accumulation of tantalite, a magnetic mineral. A ground based technique was employed using proton precision magnetometer G-856 AX. A total of ten geophysical traverses were established in the study area. The acquired magnetic field data were corrected for drift. The trend analysis was adopted to remove the regional gradient from the observed data and the resulting results were presented as profiles. Quantitative interpretation only was adopted to obtain the depth to basement using Peter half slope method. From the geological setting of the area and the information obtained from the magnetic survey, a conclusion can be made that the study area is underlain by a rock unit of accumulated minerals. It is therefore suspected that the overburden is relatively thin within the study area and the metallic minerals are in disseminated quantity and at a shallow depth.

Keywords: basement, drift, magnetic field data, tantalite, traverses

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Authors: U. Arjun, K. Brinda, M. Padmanabhan, R. Nath

Abstract:

Polycrystalline samples of rare-earth oxy-carbonates Ln2O2CO3 (Ln = Nd, Sm, and Dy) are synthesized, and their structural and magnetic properties are investigated. All of them crystallize in a hexagonal structure with space group P6_3/mmc. They form a double layered structure with frustrated triangular arrangement of rare-earth magnetic ions. An antiferromagnetic transition is observed at TN ≈ 1.25 K, 0.61 K, and 1.21 K for Nd2O2CO3, Sm2O2CO3, and Dy2O2CO3, respectively. From the analysis of magnetic susceptibility, the value of the Curie-Weiss temperature θ_CW is obtained to be ≈ 21.7 K, 18 K, and 10.6 K for Nd2O2CO3, Sm2O2CO3, and Dy2O2CO3, respectively. The magnetic frustration parameter f ( = |θ_CW|/T_N) is calculated to be ≈ 17.4, 31, and 8.8 for Nd2O2CO3, Sm2O2CO3, and Dy2O2CO3, respectively which indicates that Sm2O2CO3 is strongly frustrated compared to its Nd and Dy analogues.

Keywords: chemical synthesis, exchange and superexchange, heat capacity, magnetically ordered materials

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Authors: B. Bouadjemi, S. Bentata, A. Abbad, W.Benstaali

Abstract:

The full-potential linearized augmented plane wave method (FP-LAPW) within the Generalized Gradient Approximation (GGA) is used to calculate the magnetic and optical properties of quaternary GaFeMnN. The results show that the compound becomes magnetic and half metallic and there is an apparition of peaks at low frequencies for the optical properties.

Keywords: optical properties, DFT, Spintronic, wave

Procedia PDF Downloads 518

Authors: Zhijun Ren, Zhang Lin, Zhao Ye, Zuo Xiangyu, Mei Dongxing

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As a pretreatment process of ballast water treatment, the performance of high gradient magnetic separation (HGMS) technology for the removal of particulates and microorganisms was studied. The results showed that HGMS process could effectively remove suspended particles larger than 5 µm and had ability to resist impact load. Microorganism could also be effectively removed by HGMS process, and the removal effect increased with increasing magnetic field strength. The maximum removal rates for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were 4016.1% and 9675.3% higher, respectively, than without the magnetic field. In addition, the superoxide dismutase (SOD) activity of the microbes decreased by 32.2% when the magnetic field strength was 15.4 mT for 72 min. The microstructure of the stainless steel wool was investigated, and the results showed that particle removal by HGMS has common function by the magnetic force of the high-strength, high-gradient magnetic field on weakly magnetic particles in the water, and on the stainless steel wool.

Keywords: HGMS, particulates, superoxide dismutase (SOD) activity, steel wool magnetic medium

Procedia PDF Downloads 412

Authors: Dong-An Wang

Abstract:

All kinds of microspheres have been extensively employed as carriers for drug, gene and therapeutic cell delivery. Most therapeutic cell delivery microspheres rely on a two-step methodology: fabrication of microspheres and subsequent seeding of cells onto them. In this study, we have developed a novel one-step cell encapsulation technique using a convenient and instant water-in-oil single emulsion approach to form cell-encapsulated gelatin microspheres. This technology is adopted for hyaline cartilage tissue engineering, in which autologous chondrocytes are used as therapeutic cells. Cell viability was maintained throughout and after the microsphere formation (75-100 µm diameters) process that avoids involvement of any covalent bonding reactions or exposure to any further chemicals. Further encapsulation of cell-laden microspheres in alginate gels were performed under 4°C via a prompt process. Upon the formation of alginate constructs, they were immediately relocated into CO2 incubator where the temperature was maintained at 37°C; under this temperature, the cell-laden gelatin microspheres dissolved within hours to yield similarly sized cavities and the chondrocytes were therefore suspended within the cavities inside the alginate gel bulk. Hence, the gelatin cell-laden microspheres served two roles: as cell delivery vehicles which can be removable through temperature curing, and as porogens within an alginate hydrogel construct to provide living space for cell growth and tissue development as well as better permeability for mutual diffusions. These cell-laden microspheres, namely “temperature-cured dissolvable gelatin microsphere based cell carriers” (tDGMCs), were further encapsulated in a chondrocyte-laden alginate scaffold system and analyzed by WST-1, gene expression analyses, biochemical assays, histology and immunochemistry stains. The positive results consistently demonstrated the promise of tDGMC technology in delivering these non-anchorage dependent cells (chondrocytes). It can be further conveniently translated into delivery of other non-anchorage dependent cell species, including stem cells, progenitors or iPS cells, for regeneration of tissues in internal organs, such as engineered hepatogenesis or pancreatic regeneration.

Keywords: biomaterials, tissue engineering, microsphere, hydrogel, porogen, anchorage dependence

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Authors: Talib M. Albayati, Omar S. Mahdy, Ghanim M. Alwan

Abstract:

This work is aimed to prepare magnetic nanoporous material Fe/MCM-41 and study its Physical characterization in order to enhance the magnetic properties for study the operating conditions on separation efficiency of methyl orange (MO) from wastewater by adsorption process. The experimental results are analysed to select the best operating conditions for different studied parameters which were obtained for both adsorbents mesoporous material samples MCM-41 and magnetic Fe/MCM-41 as follow: constant temperature (20 ºC), pH: (2) adsorbent dosage (0.03 gm), contact time (10 minute) and concentrations (30 mg/L). The results are demonstrated that the adsorption processes can be well fitted by the Langmuir isotherm model for pure MCM-41 with a higher correlation coefficient (0.999) and fitted by the freundlich isotherm model for magnetic Fe/MCM-41 with a higher correlation coefficient of (0.994).

Keywords: adsorption, nanoporous materials, mcm-41, magnetic material, wastewater, orange, wastewater

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