Papers by Keyword: Magnetic Field

Abstract: Synthesis of nanomultiferroic material with the active content of bismuth ferrite (BiFeO₃) and barium titanate (BaTiO₃) was carried out. It is considering that it was difficult to obtain single phase of BiFeO₃ as a base material for multiferroic materials. It is expected that the addition of BaTiO₃ on ceramic alloys consist of BiFeO₃ and BaTiO₃ can improve the electrical properties of the ceramics and finally it improves the multiferroic properties of the material. Multiferroic properties could be seen from the appearance of an electric voltage response if the material is given the effect of an external magnetic field. The synthesis uses the sol gel method which is a good method of producing nanosized material. Synthesis of nanomultiferroic ceramic materials is carried out by varying the weight ratio of BaTiO₃ and BiFeO₃ of 2: 1, calcination temperature of 350°C for 4 hours and sintering temperatures with variations of 700°C; 750°C and 800°C for 2; 4; and 6 hours. Characterization was carried out using X Ray Diffraction (XRD) to confirm phase formation. The electrical properties test which produces a hysterical loop is carried out to determine the value of remanent, coercivity and electric polarization saturation. Particle size measurements were carried out using the Beckman Coulter DelsaTM nanoinstrument. The multiferroic phenomena is known from the appearance of an electric voltage response if there is an effect of an external magnetic field on the material. The smallest particle size was obtained on ceramic powder which experienced sintered of 750°C. The best values of remanent, coercivity and electric polarization​​ were obtained on ceramics which were sintered at temperatures of 750°C for 6 hours. This is linear with the highest value of electrical voltage arising as a result of the effect of the external magnetic field given to the ceramic material. Material that has a large electrical voltage response shows good multiferroic properties.

Abstract: The Cu/Ni thin film as low-temperature sensor was produced by electroplating on the various deposition times assisted with a 200G magnetic field in the transverse direction to the surface of Cu. The deposition time was varied from 0 to 45s. The liquid nitrogen (LN2) 0°C to -200°C was used as a tested low-temperature medium. The characterization was done on the voltage range and sensitivity. Cu/Ni sensor from deposition within 25s has the largest voltage range that is 128.48 mV and has the sensitivity (S) that has a linear relationship with temperature (T) according to S(T) = 0.287 - 0.002T.

Abstract: This study aimed to investigate the in-vivo effect of a static magnetic field (SMF) on blood falling time and velocity in a capillary tube. We generated a magnetic field using Helmholtz coils. We exposed rats with 2.4±0.2mT for a duration of one-four weeks and 1-8hrs/day. Blood samples were withdrawn and passed through a capillary viscometer under gravity. Results showed a significant reduction of blood falling time and an increase of blood falling velocity at 2 weeks exposure. The 4hrs and 8hrs exposure per day have reduced the blood falling time from 129±3.94sec to 53.2±1.80sec and 55±2.92sec respectively. The 2hrs exposure for 1 week reduced blood falling velocity from 0.19±0.004cm/sec-0.12±0.002cm/sec. The 4hrs exposure/day showed a similar trend to control samples for the entire durations except for the 4 weeks exposure, which took a long time to pass through the capillary.

Abstract: The project presents the use of laser and magnetic nanoparticles like iron oxide (Fe₃O₄) in heavy metal detection in water. In this method, metal Nanomagnets particles result in a magnetic reagent for the rapid removal of heavy metals from solutions or water of magnitude to concentration 0.25wt%. This can be done by measuring the magneto-optical parameters (as a hysteric loop) of the solution as an indication of the change in concentrations of the detected heavy metal. The samples used in this work using the Tigris River water that supported from al-Wathba lab. water projects of the Baghdad water directorate at Baghdad-Iraq. Putting here a study of the effect of graphene and metal oxide such as cobalt and nickel which doped the ferrofluid (iron oxide) /polymer/water (Tigris river water) composite on the magneto-optical properties. The graphene adding had the best result in low threshold magnetic field which was 67mGauss, give the motive to use it in fast sensing and detecting of heavy metal in Tigris river water.

Abstract: Relaxation-compression resin transfer molding under magnetic field is a new variant of VARTM (“vacuum assisted resin transfer molding”) process, which uses a flexible magnetic membrane controlled by a magnetic force, in order to govern the relaxation and compression phases by changing the permeability of the fabric preform. Thus permits to the resin to enter easily into the mold and to increase the resin impregnation velocity and the fiber volume fraction. This innovation is based on the application of the TRIZ theory (“the theory of inventive problem solving”), which allows us to answer to the shortcomings and the conflict links exist inside the VARTM processes. The objective of this paper is to present this new process and to study the effect of the current intensity and the separated gap between the flexible magnetic membrane and solenoid on the permeability of the preform.

Abstract: The structure of martensite obtained by quenching steel under the action of a constant magnetic field was studied. The kinetic changes of the martensitic transformation, caused by the action of a magnetic field, are expressed in the structure by an increase in the dispersity of the transformation products. Samples of steels C45, 100CrMn6 and 30HGSA were investigated. Dispersity was evaluated statistically in images obtained on light and electron microscopes. The specific surface area was measured and the parameters of the surface relief caused by martensitic transformation were studied. Experimental data show that after quenching in a magnetic field, a decrease in the volumetric strain of the transformation, an increase in the dispersity of packets of martensitic crystals and components of the packets are observed. It is concluded that an increase in dispersion and a fragmentation of the structure of martensite are mainly the result of multiplicative nucleation.

Abstract: The Cd₃As₂+MnAs composite with 20 mole % of MnAs has been studied complexly in a wide ranges of temperatures, pressures and magnetic fields. Negative magnetic resistance has been found in the sample. This anomalous behavior is considered as a result of changes in tunneling processes due to reduce of distance between magnetic moment of ferromagnetic and structural transitions caused by pressure.

Abstract: A surface charge density distribution on natural crystal samples is investigated in the paper. Here are revealed regularities of electromagnetic signal amplitude changes upon acoustic excitation of electrified calcite samples depending on the size of the crystals.

Abstract: The role of spin states in the process of charge carrier transport in copper phthalocyanine (CuPc) nanowires has been established. According to the data obtained, CuPc nanowires are in the η-phase. The current-voltage characteristics (IVC) of a photosensitive cell based on CuPc nanowires in a magnetic field are investigated. As a result of experiments, it was found that applying an external magnetic field, the spins of two positively charged polarons are oriented in one direction. The channel of formation of the bipolaron is blocked. As a result, a decrease in the short-circuit current of the photosensitive cell is observed by more than 61%.

Abstract: Magnetotactic bacteria integrated magnetosomes, which are unique organelles that contain nanosized crystals of biogenic magnetic iron minerals with the ability to respond to the external magnetic fields. The biogenic magnetic nanoparticles (magnetosomes) show high biocompatibility in medical applications especially as scavengers to eliminate intracellular reactive oxygen species. The aim of this study was to highlight the impact of magnetosome formation and antioxidant systems in the suppression of oxidative stress on the magnetotactic bacteria cells. To assess the changes in ROS levels under different magnetic field intensity conditions, cells were cultured under the microaerobic condition in medium containing the high and low intensity of magnetic field. Treatment of magnetic field with an intensity of 500 mT during 50 hours bionormalization process of magnetotactic bacteria increased the antioxidant enzyme activity for eliminating of free radicals by 64%. We concluded that magnetosomes production plays an important role in decreasing or eliminating ROS. This is the first study to demonstrate that the magnetic field assisted magnetosome formation and antioxidants defense systems in Magnetospirillum gryphiswaldense MSR-1.