Vector magnetic field inversions of high cadence SOLIS-VSM data

NARCIS (Netherlands)

Fischer, C.E.; Keller, C.U.; Snik, F.

2007-01-01

We have processed full Stokes observations from the SOLIS VSM in the photospheric lines Fe I 630.15 nm and 630.25 nm. The data sets have high spectral and temporal resolution, moderate spatial resolution, and large polarimetric sensitivity and accuracy. We used the LILIA, an LTE code written by

A PDCA-based approach to Environmental Value Stream Mapping (E-VSM)

DEFF Research Database (Denmark)

Garza-Reyes, Jose Arturo; Torres Romero, Joseth; Govindan, Kannan

2018-01-01

Research into the application of Value Stream Mapping (VSM) as a tool to enhance the environmental sustainability performance of operations has been confined to a handful of studies only. Research on this green lean research stream is therefore limited, especially when compared to the vast amount...

Construction and calibration of a low cost and fully automated vibrating sample magnetometer

International Nuclear Information System (INIS)

El-Alaily, T.M.; El-Nimr, M.K.; Saafan, S.A.; Kamel, M.M.; Meaz, T.M.; Assar, S.T.

2015-01-01

A low cost vibrating sample magnetometer (VSM) has been constructed by using an electromagnet and an audio loud speaker; where both are controlled by a data acquisition device. The constructed VSM records the magnetic hysteresis loop up to 8.3 KG at room temperature. The apparatus has been calibrated and tested by using magnetic hysteresis data of some ferrite samples measured by two scientifically calibrated magnetometers; model (Lake Shore 7410) and model (LDJ Electronics Inc. Troy, MI). Our VSM lab-built new design proved success and reliability. - Highlights: • A low cost automated vibrating sample magnetometer VSM has been constructed. • The VSM records the magnetic hysteresis loop up to 8.3 KG at room temperature. • The VSM has been calibrated and tested by using some measured ferrite samples. • Our VSM lab-built new design proved success and reliability

Construction and calibration of a low cost and fully automated vibrating sample magnetometer

Energy Technology Data Exchange (ETDEWEB)

El-Alaily, T.M., E-mail: toson_alaily@yahoo.com [Physics Department, Faculty of Science, Tanta University, Tanta (Egypt); El-Nimr, M.K.; Saafan, S.A.; Kamel, M.M.; Meaz, T.M. [Physics Department, Faculty of Science, Tanta University, Tanta (Egypt); Assar, S.T. [Engineering Physics and Mathematics Department, Faculty of Engineering, Tanta University, Tanta (Egypt)

2015-07-15

A low cost vibrating sample magnetometer (VSM) has been constructed by using an electromagnet and an audio loud speaker; where both are controlled by a data acquisition device. The constructed VSM records the magnetic hysteresis loop up to 8.3 KG at room temperature. The apparatus has been calibrated and tested by using magnetic hysteresis data of some ferrite samples measured by two scientifically calibrated magnetometers; model (Lake Shore 7410) and model (LDJ Electronics Inc. Troy, MI). Our VSM lab-built new design proved success and reliability. - Highlights: • A low cost automated vibrating sample magnetometer VSM has been constructed. • The VSM records the magnetic hysteresis loop up to 8.3 KG at room temperature. • The VSM has been calibrated and tested by using some measured ferrite samples. • Our VSM lab-built new design proved success and reliability.

THE IMPROVEMENT OF SUGAR DISTRIBUTION SYSTEM USING VALUE STREAM MAPPING (VSM APPROACH A CASE STUDY: INDUSTRI GULA NUSANTARA, KENDAL, JAWA TENGAH

Directory of Open Access Journals (Sweden)

Muchamad Muchfirodin

2013-06-01

Full Text Available This study was aimed to find kind of improvements of sugar distribution system using value stream mapping (VSM when some inefficiencies in physical and service activities were encountered that will cause wasting time. The VSM was directed to reduce non value added time as the performace parameter. VSM was used to analyze thus inefficiencies because using VSM can simply mapping to trace whole activities both of material and service flow from beginning to the end of process. A case study of Industri Gula Nusantara showed that in its service operations, there were an inefficiency in the process of issueing the loading order. Move thus activity a day earlier, the improvement sounds a shorter service time over order and delivery schedule which in further make a better operation and service over the whole process of sugar distribution. At same time a policy of safety stock or inventory leveling could minimize stock out occasion by the increasing of service level from 25% to 38% that was close to standard deviation of demand during lead time.   Keywords: Sugar, VSM, inventory

A simple vibrating sample magnetometer for macroscopic samples

Science.gov (United States)

Lopez-Dominguez, V.; Quesada, A.; Guzmán-Mínguez, J. C.; Moreno, L.; Lere, M.; Spottorno, J.; Giacomone, F.; Fernández, J. F.; Hernando, A.; García, M. A.

2018-03-01

We here present a simple model of a vibrating sample magnetometer (VSM). The system allows recording magnetization curves at room temperature with a resolution of the order of 0.01 emu and is appropriated for macroscopic samples. The setup can be mounted with different configurations depending on the requirements of the sample to be measured (mass, saturation magnetization, saturation field, etc.). We also include here examples of curves obtained with our setup and comparison curves measured with a standard commercial VSM that confirms the reliability of our device.

Quantum Kalman filtering and the Heisenberg limit in atomic magnetometry

Energy Technology Data Exchange (ETDEWEB)

Geremia, J M; Stockton, John K; Doherty, Andrew C; Mabuchi, Hideo [Norman Bridge Laboratory of Physics, California Institute of Technology, Pasadena, California, 91125 (United States)

2003-12-19

The shot-noise detection limit in current high-precision magnetometry [I. Kominis, T. Kornack, J. Allred, and M. Romalis, Nature (London) 422, 596 (2003)]10.1038/nature01484 is a manifestation of quantum fluctuations that scale as 1/{radical}(N) in an ensemble of N atoms. Here, we develop a procedure that combines continuous measurement and quantum Kalman filtering [V. Belavkin, Rep. Math. Phys. 43, 405 (1999)] to surpass this conventional limit by exploiting conditional spin squeezing to achieve 1/N field sensitivity. Our analysis demonstrates the importance of optimal estimation for high bandwidth precision magnetometry at the Heisenberg limit and also identifies an approximate estimator based on linear regression.

Sol-gel route of synthesis of nanoparticles of MgFe2O4 and XRD, FTIR and VSM study

International Nuclear Information System (INIS)

Pradeep, A.; Priyadharsini, P.; Chandrasekaran, G.

2008-01-01

Nanoparticles of MgFe 2 O 4 are synthesized using sol-gel autocombustion method. Structural studies are carried out using X-ray diffraction (XRD). The XRD pattern of MgFe 2 O 4 provides information about single-phase formation of spinel structure with cubic symmetry. The grain size and lattice constant are obtained using XRD data. The cation distribution is also proposed theoretically. The change in site preference of cations in nano-MgFe 2 O 4 is compared with its bulk counterpart. The structural morphology of the nanoparticles is studied using Scanning Electron Microscopy (SEM). Formation of spinel structure is conformed using Fourier transform infrared spectroscopy (FTIR), which also lends support for the cation distribution proposed using XRD data. The effect of nanoregime on parameters such as bond length, vibration frequency and force constant are discussed with the help of FTIR data. The M-H loop of MgFe 2 O 4 has been traced using the Vibrating Sample Magnetometer (VSM) and magnetic parameters such as saturation magnetization (M S ), coercivity (H C ) and retentivity (M R ) are obtained from VSM data

Prospects on the application of HTS SQUID magnetometry to nondestructive evaluation (NDE)

Science.gov (United States)

Weinstock, H.

1993-04-01

In light of recent advances in the fabrication of low-noise HTS SQUIDs, a review is presented on the use of LTS SQUID magnetometry for nondestructive evaluation (NDE). Examples are given on applications relating to defects in steel, subsurface cracks in aircraft frames, and voids in non-metallic structures. HTS SQUIDs may make a significant difference in the acceptance of these applications because sensing coils will be closer to a sample under test, there will be greater instrument portability and the problem of bringing liquid helium to remote locations will be eliminated.

Influence of synthesis experimental parameters on the formation of nanoparticles of magnetite prepared by thermal decomposition method

International Nuclear Information System (INIS)

Vega, Jaime; Picasso, Gino; Lopez, Alcides; Aviles Felix, Luis

2013-01-01

In this work, nanoparticles based on magnetite have been synthesized by thermal decomposition via solvent-controlled synthesis in polyols, using triethylene glycol (TREG). The starting precursor were solutions of nitrate and acetylacetonate of Fe. The samples have been characterized by X-ray diffraction technique (XRD), adsorption-desorption of N 2 (BET equation model), scanning electronic microscopy (SEM), thermogravimetric analysis (TGA), vibration sample magnetometry (VSM) and Moessbauer spectroscopy. XRD diffractogram revealed the majority presence of spinel-like structural phases of magnetite in all samples. SEM micrographs showed morphological differences; the samples prepared from acetylacetonate presented good dispersion of particles whereas the ones prepared from nitrate-small agglomerations. BET isotherms of samples depicted a mesoporous profile which corresponded to IV type. TGA thermogram showed two defined regions which corresponded to vaporization of polyol light fractions and TREG. Zero coercivity on the magnetization curve of acetylacetonate precursor samples have been observed by VSM, which indicates superparamagnetic behavior. Moessbauer spectra of samples detected the presence of 4 doublet-like subspectra due to the presence of 4 sites occupied by Fe in paramagnetic or superparamagnetic state. (author)

Exchange coupling in hybrid anisotropy magnetic multilayers quantified by vector magnetometry

Energy Technology Data Exchange (ETDEWEB)

Morrison, C., E-mail: C.Morrison.2@warwick.ac.uk; Miles, J. J.; Thomson, T. [School of Computer Science, University of Manchester, Manchester M13 9PL (United Kingdom); Anh Nguyen, T. N. [Materials Physics, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Spintronics Research Group, Laboratory for Nanotechnology (LNT), VNU-HCM, Ho Chi Minh City (Viet Nam); Fang, Y.; Dumas, R. K. [Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden); Åkerman, J. [Materials Physics, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden)

2015-05-07

Hybrid anisotropy thin film heterostructures, where layers with perpendicular and in-plane anisotropy are separated by a thin spacer, are novel materials for zero/low field spin torque oscillators and bit patterned media. Here, we report on magnetization reversal and exchange coupling in a archetypal Co/Pd (perpendicular)-NiFe (in-plane) hybrid anisotropy system studied using vector vibrating sample magnetometry. This technique allows us to quantify the magnetization reversal in each individual magnetic layer, and measure of the interlayer exchange as a function of non-magnetic spacer thickness. At large (>1 nm) spacer thicknesses Ruderman-Kittel-Kasuya-Yosida-like exchange dominates, with orange-peel coupling providing a significant contribution only for sub-nm spacer thickness.

Low dimensional magnetism and nanograined materials - magnetometry, magnetooptics and laser-ultrasound

International Nuclear Information System (INIS)

Krenn, H.; Paltauf, G.; Rumpf, K.; Granitzer, P.; Kozhushko, V.; Nadeem, K.; Hofmayer, M.

2008-01-01

Full text: The working group 'Magnetometry and Photonics' headed by H. Krenn has directed its research focus on magnetic phenomena and properties of nanoscaled materials which are random or self assembled (principal investigators: K. Rumpf and P. Granitzer). Another activity is concerned with optoacoustics investigating the propagation and damping of ultrasound waves in non-magnetic (severely deformed) as well as bulk-nanostructured magnetic materials (principal investigators: G. Paltauf and V. Kozhusko). The gap between self assembled (1-dim) and randomly dense (bulk 3-dim) nanomagnets is bridged by preparation of ferrite-(0-dim) nanoparticles (PhD: K. Nadeem) dispersed in a SiO 2 or polymer matrix. As a template for magnetic nanowires and nanodots porous silicon is prepared by electrochemical methods. Remarkable magnetic effects beyond conventional spin-magnetism are experimentally observed by SQUID-magnetometry at high magnetic fields (7 T) and by spectroscopic magnetooptics from the infrared to VIS. The main purposes and aims of this hybrid system are experimental efforts to detect the spin injection and electronic transport from a ferromagnetic metal into silicon, and the possible development of direction dependent magnetic-field-sensors due to the strong magnetic anisotropy of the nanocomposite at high magnetic fields (> 2 T). By co-precipitation and sol-gel methods (Ni,Co)Fe 2 O 4 superparamagnetic ferrite nanoparticles (d < 20 nm) are produced. Both systems have a potential for drug delivery using magnetic carriers, but also for magnetic targeting of tumors where the former Si-based system is promising because of the biodegradability and biocompatibility of porous silicon. On the other hand steel samples offer nanoscopic grain refinement under severe plastic deformation and highly deformed magnetic materials show a softening of the magnetization, reflected in modified Barkhausen noise spectrum and ultrasound (magnetoacoustic) phenomena. Electric tunability

Micro-Hall magnetometry on a Co-organic chain compound

International Nuclear Information System (INIS)

Rolland, L.; Simonet, V.; Wernsdorfer, W.; Bogani, L.; Sessoli, R.

2004-01-01

The static and dynamical properties of Co-organic chains, with strong magnetic anisotropy, are studied by micro-Hall magnetometry. The low-temperature hysteresis cycles are discussed with respect to the helical structure of the chains. Thermally activated relaxation of the magnetization is observed, compatible with the Glauber model for a 1D Ising system

Micro-Hall magnetometry on a Co-organic chain compound

Energy Technology Data Exchange (ETDEWEB)

Rolland, L.; Simonet, V. E-mail: simonet@grenoble.cnrs.fr; Wernsdorfer, W.; Bogani, L.; Sessoli, R

2004-05-01

The static and dynamical properties of Co-organic chains, with strong magnetic anisotropy, are studied by micro-Hall magnetometry. The low-temperature hysteresis cycles are discussed with respect to the helical structure of the chains. Thermally activated relaxation of the magnetization is observed, compatible with the Glauber model for a 1D Ising system.

Static and dynamic magnetization properties of Y1Ba2Cu3Oz thin films

International Nuclear Information System (INIS)

Sekula, S.T.

1989-08-01

Magnetization studies were carried out on Y 1 Ba 2 Cu 3 O z (YBCO) thin films that were e-beam evaporated onto circular discs of single-crystal SrTiO 3 with (001) and (110) faces as well as KTaO 3 with (001) faces. The measurements were made using vibrating sample (VSM) and SQUID-based magnetometry with the applied field perpendicular to the substrate surface. Critical current densities J c (H,T) are deduced from the magnetic hysteresis. Flux creep effects are observed over longer periods with the SQUID magnetometer. Analysis of the results of low frequency response of these films to collinear ac and dc magnetic fields are compared with the dc magnetometry results. J c (H,T) is observed to be quite sensitive to the type of epitaxial growth on the various substrates. 16 refs., 10 figs

Hybrid Organometallic-Inorganic Nanomaterial: Acetyl Ferrocene Schiff base Immobilized on Silica Coated Magnetite Nanoparticles

Directory of Open Access Journals (Sweden)

M. Masteri-Farahani

2015-10-01

Full Text Available In  this  work,  a  new  hybrid  organometallic-inorganic  hybrid nanomaterial was prepared by immobilization of acetyl ferrocene on the  surface  of magnetite  nanoparticles. Covalent  grafting of silica coated magnetite nanoparticles (SCMNPs with 3-aminopropyl triethoxysilane gave aminopropyl-modified magnetite nanoparticles (AmpSCMNPs. Then, Schiff base condensation  of AmpSCMNPs with acetyl  ferrocene resulted in the preparation of acferro-SCMNPs hybrid nanomaterial. Characterization of the prepared nanomaterial was performed with different physicochemical methods such as Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD, vibrating sample magnetometry (VSM, thermogravimetric analysis (TGA, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. VSM analysis showed superparamagnetic properties of the prepared nanomaterial and TEM and SEM analyses indicated the relatively spherical nanoparticles with 15 nm average size.

A SQUID magnetometry system for a cryogenic neutron electric dipole moment experiment

Energy Technology Data Exchange (ETDEWEB)

Henry, S., E-mail: s.henry@physics.ox.ac.uk; Clarke, C.; Cottle, A.; Lynch, A.; Pipe, M.

2014-11-01

Precision magnetometry is an essential component of any neutron electric dipole moment experiment in order to correct shifts in the neutron precession frequency due to changes in the magnetic field. We have developed a magnetometry system using 12 SQUID sensors, designed to operate in 0.5 K superfluid helium. The pick-up loops located near the neutron cell are connected to the SQUID sensors by ∼2 m twisted wire pairs. The SQUID readout cables are run via an intermediate stage at 4.2 K. The system has been installed and tested in the cryoEDM apparatus at the ILL, Grenoble, and used to characterise the magnetic environment. Further tests in a suitable low noise environment confirm it meets our requirements.

Magneto-optical measurement of anisotropy energy constant(s) for amorphous rare earth, transition metal alloys

International Nuclear Information System (INIS)

Uber, R.E.; Mansuripur, M.

1988-01-01

Optical investigation of magneto-optical films is complementary to conventional torque and VSM magnetometry. In the authors' laboratory, they are now measuring anisotropy energy constants of RE-TM thin films at temperatures from ambient to 150 0 C. An in-plane magnetic field (up to 16.5 KOe) is applied to a saturated sample with perpendicular magnetization. The movement away from the perpendicular direction is monitored using the polar Kerr effect. At the HeNe wavelength, the Kerr effect is principally due to the top 500 angstroms of the transition metal subnetwork in the films

Magnetic and Structural Properties of Electrodeposited Iron on Copper and Silver

International Nuclear Information System (INIS)

Koempe, K.; Kuehl, E.; Nagorny, K.

2002-01-01

Electrodeposition of iron on copper or silver leads to the formation of bcc-iron or amorphous iron. Thermal annealing usually results in soluted iron (also γ-iron and clusters) in copper. On silver the insolubility of iron never causes the formation of bcc-iron. Instead on copper as well as on silver fcc-iron states are formed, especially at relatively low temperatures with short times of annealing. Moessbauer spectroscopy accompanied by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) are applied for characterisation of the iron states.

Observation of the structural, optical and magnetic properties during the transformation from hexagonal NiS nano-compounds to cubic NiO nanostructures due to thermal oxidation

Energy Technology Data Exchange (ETDEWEB)

Linganiso, E.C., E-mail: elinganiso@csir.co.za [National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001 (South Africa); DST/NRF Centre of Excellence in Strong Materials, Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Johannesburg, Wits 2050 (South Africa); Mwakikunga, B.W., E-mail: bmwakikunga@csir.co.za [National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001 (South Africa); Coville, N.J. [DST/NRF Centre of Excellence in Strong Materials, Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Johannesburg, Wits 2050 (South Africa); Mhlanga, S.D. [Department of Applied Chemistry, University of Johannesburg, PO Box 17011, Doornfontein, 2028 Johannesburg (South Africa)

2015-04-25

Graphical abstract: The transition temperature of 350 °C for the formation of c-NiO from h-NiS oxidation was obtained from structural and optical property studies and by calculating the number of spins obtained from the EPR data. Vibrating sample magnetometry (VSM) shows that this pure NiS has both ferromagnetic ordering and paramagnetic domains. Further, the transition temperature of −9 °C of the pure α-NiS nano-alloys was confirmed by performing electrical measurements on the as-synthesized material. - Highlights: • Single hexagonal phase NiS obtained by microwave assisted hydrothermal synthesis. • NiS nanoalloys show both ferromagnetic and paramagnetic domains by VSM. • Structural evolution of annealed NiS and temperature dependent NiS oxidation presented. • Phase transition from NiS to NiO studied and correlated to the EPR spin population data and crystallite size. • Ferromagnetic and paramagnetic ordering observed for the raw NiS nanostructures. - Abstract: Single phase α-NiS nano-compounds with uniformly distributed hierarchical networks were synthesized by a microwave-assisted hydrothermal technique. The materials were evaluated for thermal stability under an oxidative environment and at temperatures between 150 °C and 600 °C. NiS materials showed stability at 300 °C and NiO formation was observed from 350 °C to 600 °C. The annealing effect on the crystalline size and IR absorption of the annealed samples is reported by XRD and FTIR studied. The EPR properties of the annealed materials were studied and compared to the oxidized materials. The transition temperature of 350 °C for the formation of NiO from NiS oxidation was confirmed by calculating the number of spins obtained from the EPR data. Vibrating sample magnetometry (VSM) shows that this pure NiS has both ferromagnetic ordering and paramagnetic domains. Further, the transition temperature of −9 °C of the pure α-NiS nano-compounds was confirmed by performing electrical

Synthesis and magnetic properties of Ta/NdFeB-based composite microwires

Energy Technology Data Exchange (ETDEWEB)

Szary, P., E-mail: philipp.szary@uni.lu; Périgo, E. A.; Michels, A. [Physics and Materials Science Research Unit, University of Luxembourg, 162 Avenue de la Faïencerie, L-1511 Luxembourg, Grand Duchy of Luxembourg (Luxembourg); Luciu, I.; Duday, D.; Wirtz, T.; Choquet, P. [Science and Analysis of Materials (SAM), Centre de Recherche Public—Gabriel Lippmann, 41, rue du Brill, L-4422 Belvaux, Grand Duchy of Luxembourg (Luxembourg)

2015-05-07

Magnetic NdFeB-based microwire composites have been prepared by the direct current magnetron sputtering technique in a specifically designed sputtering chamber for thin-film deposition in wire geometry. As substrate wire material, we have employed steel and Ta. Annealing of the substrate wires during the deposition process was performed by ohmic heating through the application of a direct current. Samples were characterized by means of vibrating sample magnetometry (VSM) and scanning electron microscopy. Best properties have been encountered when using Ta wires as core (substrate) material. The VSM data show a dramatic impact of the current applied during the deposition process on the magnetic properties. For higher current values, i.e., higher annealing temperatures, the wires exhibit a reversal process that is typical for a two-phase system. Moreover, an increase of the coercive field (and remanent magnetization) is observed, which is ascribed to a modification of the magnetic phase present in the sample due to the annealing. We find an indication for the formation of a magnetic easy-axis direction which is azimuthally oriented around the wire axis.

Cantilever torque magnetometry on coordination compounds

DEFF Research Database (Denmark)

Perfetti, Mauro

2017-01-01

compounds, such as quantum computation or information storage. This review enlightens that CTM offers a unique combination of accuracy and precision to disentangle noncollinear contributions inside Single Crystals as well as the sensitivity to detect molecular order of thin films. CTM can also detect......Cantilever Torque Magnetometry (CTM) is one of the leading techniques to deeply understand magnetic anisotropy of coordination compounds. The knowledge of magnetic anisotropy is a mandatory requirement before proceeding with any future application related to the magnetic properties of coordination...... quantum phenomena such as magnetization steps and molecular hysteresis curves. Moreover, it can also provide the energy levels splitting and avefunctions composition, especially if coupled with microwave radiation....

Fe{sub 3}C/Fe nanoparticles with urea: Synthesis, structure and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaobai [College of Chemistry, Jilin University, Changchun, 130012 (China); School of Chemical and Pharmaceutical Engineering, Jilin Institute of Chemical Technology, Jilin, 132022 (China); Zhang, Daguang [Department of Orthopaedic Surgery, the First Hospital of Jilin University, Changchun, 130021 China (China); Ren, Xiaozhen; Gao, Jiajia [College of Chemistry, Jilin University, Changchun, 130012 (China); Han, Yu [Department of Chemistry, College of Science, Yanbian University, Yanji, 133002 China (China); Chen, Xiaodong [College of Chemistry, Jilin University, Changchun, 130012 (China); Shi, Zhan [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, 130012 (China); Yang, Hua [College of Chemistry, Jilin University, Changchun, 130012 (China)

2016-12-15

Fe{sub 3}C/Fe nanocomposites were synthesized by a sol–gel method. Using urea as carbon source and reduce agent in the reaction process. The CTAB works as the surfactant and the bromine contained in CTAB plays a catalytic role. Appropriate choices of the amount of urea and CTAB, reaction temperature and time are very important to obtain high-quality of products. Above 650 °C, the precursor gel turned into the nanocomposites composed of iron carbide and iron. Their structures and magnetic properties are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The possible formation mechanism of as-prepared nanostructures is discussed. - Highlights: • The Fe{sub 3}C/Fe composites were synthetized by sol–gel method. • Their structure, magnetic properties are researched by XRD, VSM and TEM. • The possible formation mechanisms of the composites is discussed.

Effects of Cr and Fe co-doping on structural, optical, electrical and magnetic properties of titanium dioxide (TiO2

Directory of Open Access Journals (Sweden)

Waseem Salma

2015-09-01

Full Text Available A series of Ti0.9Fe0.1-xCrxO2 (where x = 0.0, 0.02, 0.04, 0.6, 0.08, 0.10 was synthesized using the powder metallurgy route. The structural, morphological, magnetic, optical and electrical properties were investigated by X-ray diffractometry (XRD, Raman spectroscopy, scanning electron microscopy (SEM, vibrating sample magnetometry (VSM, UV-Vis spec­troscopy and four probe technique, respectively. The rutile phase was confirmed by XRD analysis which was also verified by Raman spectroscopy. It was observed that the grain size increased as the concentration of Cr increased. M-H loops ex­tracted from VSM analysis revealed anti-ferromagnetic, weak ferromagnetic and paramagnetic behaviors at room temperature. The band gap energy and resistivity measurements exhibited the semiconducting nature of Ti0.9Fe0.1-xCrxO2 based diluted magnetic semiconductors.

Construction and calibration of a low cost and fully automated vibrating sample magnetometer

Science.gov (United States)

El-Alaily, T. M.; El-Nimr, M. K.; Saafan, S. A.; Kamel, M. M.; Meaz, T. M.; Assar, S. T.

2015-07-01

A low cost vibrating sample magnetometer (VSM) has been constructed by using an electromagnet and an audio loud speaker; where both are controlled by a data acquisition device. The constructed VSM records the magnetic hysteresis loop up to 8.3 KG at room temperature. The apparatus has been calibrated and tested by using magnetic hysteresis data of some ferrite samples measured by two scientifically calibrated magnetometers; model (Lake Shore 7410) and model (LDJ Electronics Inc. Troy, MI). Our VSM lab-built new design proved success and reliability.

Synthesis and characterization of graphene quantum dots/cobalt ferrite nanocomposite

Science.gov (United States)

Ramachandran, Shilpa; Sathishkumar, M.; Kothurkar, Nikhil K.; Senthilkumar, R.

2018-02-01

A facile method has been developed for the synthesis of a graphene quantum dots/cobalt ferrite nanocomposite. Graphene quantum dots (GQDs) were synthesized by a simple bottom-up method using citric acid, followed by the co-precipitation of cobalt ferrite nanoparticles on the graphene quantum dots. The morphology, structural analysis, optical properties, magnetic properties were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis absorption spectroscopy, fluorescence spectroscopy, vibrating sample magnetometry (VSM) measurements. The synthesized nanocomposite showed good fluorescence and superparamagnetic properties, which are important for biomedical applications.

Video self-modeling in children with autism: a pilot study validating prerequisite skills and extending the utilization of VSM across skill sets.

Science.gov (United States)

Williamson, Robert L; Casey, Laura B; Robertson, Janna Siegel; Buggey, Tom

2013-01-01

Given the recent interest in the use of video self-modeling (VSM) to provide instruction within iPod apps and other pieces of handheld mobile assistive technologies, investigating appropriate prerequisite skills for effective use of this intervention is particularly timely and relevant. To provide additional information regarding the efficacy of VSM for students with autism and to provide insights into any possible prerequisite skills students may require for such efficacy, the authors investigated the use of VSM in increasing the instances of effective initiations of interpersonal greetings for three students with autism that exhibited different pre-intervention abilities. Results showed that only one of the three participants showed an increase in self-initiated greetings following the viewing of videos edited to show each participant self-modeling a greeting when entering his or her classroom. Due to the differences in initial skill sets between the three children, this finding supports anecdotally observed student prerequisite abilities mentioned in previous studies that may be required to effectively utilize video based teaching methods.

Bending strain study of Bi-2223/Ag tapes using Hall sensor magnetometry

International Nuclear Information System (INIS)

Lahtinen, M.; Paasi, J.; Sarkaniemi, J.; Han, Z.; Freltoft, T.

1996-01-01

The influence of room temperature bending on critical current (I c ) of Bi-2223/Ag tapes is studied by Hall sensor magnetometry, four-point method and scanning electron microscopy. Hall sensor magnetometry allows one to assess tape homogeneity and the amount of mechanical damage caused by bending. The microstructure of the Bi-2223 ceramic is found to strongly affect the tape behavior under bending strain. In a tape with moderate I c = 6.1 A at 77 K and a porous ceramic core, crack propagation took place normal to the Ag-ceramic interface, whereas in tapes with dense core, I c above 10 A at 77 K, cracks propagated in the tape plane. In monofilamentary tapes core homogeneity correlated with good bending strain performance. In multifilamentary tapes crack propagation between filaments was prohibited by the Ag matrix, thus leading to enhanced strain tolerance. In the high I c tapes studied, bending to 25 mm radius resulted in 1%--2% I c degradation

Direct surface magnetometry with photoemission magnetic x-ray dichroism

Energy Technology Data Exchange (ETDEWEB)

Tobin, J.G.; Goodman, K.W. [Lawrence Berkeley National Lab., CA (United States); Schumann, F.O. [Pennsylvania State Univ., University Park, PA (United States)] [and others

1997-04-01

Element specific surface magnetometry remains a central goal of synchrotron radiation based studies of nanomagnetic structures. One appealing possibility is the combination of x-ray absorption dichroism measurements and the theoretical framework provided by the {open_quotes}sum rules.{close_quotes} Unfortunately, sum rule analysis are hampered by several limitations including delocalization of the final state, multi-electronic phenomena and the presence of surface dipoles. An alternative experiment, Magnetic X-Ray Dichroism in Photoelectron Spectroscopy, holds out promise based upon its elemental specificity, surface sensitivity and high resolution. Computational simulations by Tamura et al. demonstrated the relationship between exchange and spin orbit splittings and experimental data of linear and circular dichroisms. Now the authors have developed an analytical framework which allows for the direct extraction of core level exchange splittings from circular and linear dichroic photoemission data. By extending a model initially proposed by Venus, it is possible to show a linear relation between normalized dichroism peaks in the experimental data and the underlying exchange splitting. Since it is reasonable to expect that exchange splittings and magnetic moments track together, this measurement thus becomes a powerful new tool for direct surface magnetometry, without recourse to time consuming and difficult spectral simulations. The theoretical derivation will be supported by high resolution linear and circular dichroism data collected at the Spectromicroscopy Facility of the Advanced Light Source.

Stray-field-induced Faraday contributions in wide-field Kerr microscopy and -magnetometry

International Nuclear Information System (INIS)

Markó, D.; Soldatov, I.; Tekielak, M.; Schäfer, R.

2015-01-01

The magnetic domain contrast in wide-field Kerr microscopy on bulk specimens can be substantially distorted by non-linear, field-dependent Faraday rotations in the objective lens that are caused by stray-field components emerging from the specimen. These Faraday contributions, which were detected by Kerr-magnetometry on grain-oriented iron–silicon steel samples, are thoroughly elaborated and characterized. They express themselves as a field-dependent gray-scale offset to the domain contrast and in highly distorted surface magnetization curves if optically measured in a wide field Kerr microscope. An experimental method to avoid such distortions is suggested. In the course of these studies, a low-permeability part in the surface magnetization loop of slightly misoriented (110)-surfaces in iron–silicon sheets was discovered that is attributed to demagnetization effects in direction perpendicular to the sheet surface. - Highlights: • Magnetizing a finite sample in a Kerr microscope leads to sample-generated stray-fields. • They cause non-linear, field- and position-dependent Faraday rotations in the objective. • This leads to a modulation of the Kerr contrast and to distorted MOKE loops. • A method to compensate these Faraday rotations is presented

Magnetometry of low-dimensional electron and hole systems

Energy Technology Data Exchange (ETDEWEB)

Usher, A [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Elliott, M [School of Physics and Astronomy, Cardiff University, Queens Buildings, Cardiff CF24 3AA (United Kingdom)], E-mail: a.usher@exeter.ac.uk, E-mail: elliottm@cf.ac.uk

2009-03-11

The high-magnetic-field, low-temperature magnetic properties of low-dimensional electron and hole systems reveal a wealth of fundamental information. Quantum oscillations of the thermodynamic equilibrium magnetization yield the total density of states, a central quantity in understanding the quantum Hall effect in 2D systems. The magnetization arising from non-equilibrium circulating currents reveals details, not accessible with traditional measurements, of the vanishingly small longitudinal resistance in the quantum Hall regime. We review how the technique of magnetometry has been applied to these systems, the most important discoveries that have been made, and their theoretical significance. (topical review)

Icelandic National Culture compared to National Cultures of 25 OECD member states using VSM94

Directory of Open Access Journals (Sweden)

Svala Guðmundsdóttir

2015-06-01

Full Text Available Researchers such as Hofstede (2002 and House, Hanges, Javidan, Dorfman and Gupta, (2004 have defined well-known cultural clusters such as, Anglo, Germanic, and Nordic cultural clusters. However, Iceland was not incorporated in these studies and therefore the research question of this paper is: In relation to Hofstede´s five cultural dimensions where does Iceland differ in relation to 25 of the OECD member states using VSM94? A questionnaire was sent to students at the University of Iceland, School of Social Sciences by e-mail in October 2013. The five dimensions of national culture were measured using scales developed by Hofstede called VSM 94. The results indicated that Iceland differs considerably from nations such as Slovakia, Japan, India, Thailand and China, which were found high in PDI and the MAS dimension while Iceland was found to be high in IDV and low in PDI. When considering the 25 OECD countries, Iceland is more similar to the Anglo cluster, C3, Canada, New Zealand, United Kingdon, Australia and United States than the Nordic cluster, C1 i.e. Denmark, Sweden and Norway. Iceland is similar to those countries in relation to high IDV, low PDI but differs in the dimensions MAS and UAI where Iceland scores higher.

Determination of critical exponents of inhomogeneous Gd films

Energy Technology Data Exchange (ETDEWEB)

Rosales-Rivera, A., E-mail: arosalesr@unal.edu.co [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Salazar, N.A. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Hovorka, O.; Idigoras, O.; Berger, A. [CIC nanoGUNE Consolider, Tolosa Hiribidea 76, E-20018 Donostia-San Sebastian (Spain)

2012-08-15

The role of inhomogeneity on the critical behavior is studied for non-epitaxial Gd films. For this purpose, the film inhomogeneity was varied experimentally by annealing otherwise identical samples at different temperatures T{sub AN}=200, 400, and 500 Degree-Sign C. Vibrating sample magnetometry (VSM) was used for magnetization M vs. T measurements at different external fields H. A method based upon the linear superposition of different sample parts having different Curie temperatures T{sub C} was used to extract the critical exponents and the intrinsic distribution of Curie temperatures. We found that this method allows extracting reliable values of the critical exponents for all annealing temperatures, which enabled us to study the effects of disorder onto the universality class of Gd films.

Determination of critical exponents of inhomogeneous Gd films

International Nuclear Information System (INIS)

Rosales-Rivera, A.; Salazar, N.A.; Hovorka, O.; Idigoras, O.; Berger, A.

2012-01-01

The role of inhomogeneity on the critical behavior is studied for non-epitaxial Gd films. For this purpose, the film inhomogeneity was varied experimentally by annealing otherwise identical samples at different temperatures T AN =200, 400, and 500 °C. Vibrating sample magnetometry (VSM) was used for magnetization M vs. T measurements at different external fields H. A method based upon the linear superposition of different sample parts having different Curie temperatures T C was used to extract the critical exponents and the intrinsic distribution of Curie temperatures. We found that this method allows extracting reliable values of the critical exponents for all annealing temperatures, which enabled us to study the effects of disorder onto the universality class of Gd films.

Measuring SPIO and Gd contrast agent magnetization using 3 T MRI

Science.gov (United States)

Cantillon-Murphy, Pádraig; Wald, Lawrence L.; Zahn, Markus; Adalsteinsson, Elfar

2011-01-01

Traditional methods of measuring magnetization in magnetic fluid samples, such as vibrating sample magnetometry (VSM), are typically limited to maximum field strengths of about 1 T. This work demonstrates the ability of MRI to measure the magnetization associated with two commercial MRI contrast agents at 3 T by comparing analytical solutions to experimental imaging results for the field pattern associated with agents in cylindrical vials. The results of the VSM and fitted MRI data match closely. The method represents an improvement over VSM measurements since results are attainable at imaging field strengths. The agents investigated are Feridex, a superparamagnetic iron oxide suspension used primarily for liver imaging, and Magnevist, a paramagnetic, gadolinium-based compound used for tumors, inflammation and vascular lesions. MR imaging of the agents took place in sealed cylindrical vials in the presence of a surrounding volume of deionized water where the effects of the contrast agents had a measurable effect on the water's magnetization in the vicinity of the compartment of contrast agent. A pair of phase images were used to reconstruct a B0 fieldmap. The resultant B0 maps in the water region, corrected for shimming and container edge effects, were used to predict the agent's magnetization at 3 T. The results were compared with the results from VSM measurements up to 1.2 T and close correlation was observed. The technique should be of interest to those seeking quantification of the magnetization associated with magnetic suspensions beyond the traditional scope of VSM. The magnetization needs to be sufficiently strong (Ms≳50 Am2/kg Fe for Feridex and χm≳5 × 10−5 m3/kg Gd for Magnevist) for a measurable dipole field in the surrounding water. For this reason, the technique is mostly suitable for undiluted agents. PMID:19588450

Thin films of NdFeB deposited by PLD technique

International Nuclear Information System (INIS)

Constantinescu, C.; Scarisoreanu, N.; Moldovan, A.; Dinescu, M.; Petrescu, L.; Epureanu, G.

2007-01-01

Neodymium-iron-boron (NdFeB) is a material with important magnetic properties, mostly used in permanent magnet fabrication. Thin layers of NdFeB are needed for miniaturization in electrical engineering, electronics and for high-tech devices. In this paper we applied pulsed lased deposition (PLD) in vacuum for obtaining thin films of NdFeB from stoichiometric targets. The influence of different buffer layers and of the laser parameters (wavelength and fluence) on the NdFeB structures, composition and magnetic properties have been investigated. The obtained structures were characterized by atomic force microscopy (AFM) and optical microscopy. Vibrating sample magnetometry (VSM) has been performed for specific magnetic characterization

Thin films of NdFeB deposited by PLD technique

Energy Technology Data Exchange (ETDEWEB)

Constantinescu, C. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO-077125 Magurele, Bucharest (Romania); Scarisoreanu, N. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO-077125 Magurele, Bucharest (Romania); Moldovan, A. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO-077125 Magurele, Bucharest (Romania); Dinescu, M. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO-077125 Magurele, Bucharest (Romania)]. E-mail: dinescum@ifin.nipne.ro; Petrescu, L. [Department of Electrical Engineering, ' Politehnica' University of Bucharest, 313 Spl. Independentei, 060042 Bucharest (Romania); Epureanu, G. [Department of Electrical Engineering, ' Politehnica' University of Bucharest, 313 Spl. Independentei, 060042 Bucharest (Romania)

2007-07-31

Neodymium-iron-boron (NdFeB) is a material with important magnetic properties, mostly used in permanent magnet fabrication. Thin layers of NdFeB are needed for miniaturization in electrical engineering, electronics and for high-tech devices. In this paper we applied pulsed lased deposition (PLD) in vacuum for obtaining thin films of NdFeB from stoichiometric targets. The influence of different buffer layers and of the laser parameters (wavelength and fluence) on the NdFeB structures, composition and magnetic properties have been investigated. The obtained structures were characterized by atomic force microscopy (AFM) and optical microscopy. Vibrating sample magnetometry (VSM) has been performed for specific magnetic characterization.

Mikro-Hall-Magnetometrie an ferromagnetischen Nanostrukturen im Vortex- und Single-Domain-Regime

OpenAIRE

Stahl, Joachim

2007-01-01

Diese Arbeit beschäftigt sich mit der Untersuchung des Ummagnetisierungsverhaltens ferromagnetischer Permalloy-Kreisscheiben. Im Gegensatz zu integralen Methoden, die über eine Vielzahl nominell identischer Strukturen mitteln, wird das individuelle Schaltverhalten einzelner Strukturen analysiert. Die Untersuchungen erfolgten dabei mit Hilfe der Mikro-Hall-Magnetometrie und der Lorentz-Transmissions-Elektronen-Mikroskopie und werden mit mikromagnetischen Simulationen verglichen. Für die Hall-M...

DESIGN AND CALIBRATION OF A VIBRANT SAMPLE MAGNETOMETER: CHARACTERIZATION OF MAGNETIC MATERIALS

Directory of Open Access Journals (Sweden)

Freddy P. Guachun

2018-01-01

Full Text Available This paper presents the process followed in the implementation of a vibrating sample magnetometer (VSM, constructed with materials commonly found in an electromagnetism laboratory. It describes the design, construction, calibration and use in the characterization of some magnetic materials. A VSM measures the magnetic moment of a sample when it is vibrated perpendicular to a uniform magnetic field; Magnetization and magnetic susceptibility can be determined from these readings. This instrument stands out for its simplicity, versatility and low cost, but it is very sensitive and capable of eliminating or minimizing many sources of error that are found in other methods of measurement, allowing to obtain very accurate and reliable results. Its operation is based on the law of magnetic induction of Lenz-Faraday that consists in measuring the induced voltage in coils of detection produced by the variation of the magnetic flux that crosses them. The calibration of the VSM was performed by means of a standard sample (Magnetite and verified by means of a test sample (Nickel.

Development of measurement protocols for quantum magnetometry

DEFF Research Database (Denmark)

Stark, Alexander

and protocols to enhance the lifetime and the coherences of the NV center with the overall goal of enhancing the capabilities of this sensor in the field of magnetometry. In order to realize complex protocols, a sophisticated software control of the measurement setup is required. A general software framework......, is serving as rigorous framework to reduce the complexity of the setup configuration by a fundamental separation of tasks. As a consequence, the general idea of this framework is not limited to experiments with color centers in diamond, but can find application in any laboratory environment. The measurement...... of magnetic fields in the high-frequency GHz regimes is challenging. In this thesis, a continuous dynamical decoupling protocol is developed and implemented, which extends the capabilities of the NV sensor to probe GHz signals with a narrow bandwidth. Moreover, the protocol protects the system from noise...

Experimental Learning of Digital Power Controller for Photovoltaic Module Using Proteus VSM

Directory of Open Access Journals (Sweden)

Abhijit V. Padgavhankar

2014-01-01

Full Text Available The electric power supplied by photovoltaic module depends on light intensity and temperature. It is necessary to control the operating point to draw the maximum power of photovoltaic module. This paper presents the design and implementation of digital power converters using Proteus software. Its aim is to enhance student’s learning for virtual system modeling and to simulate in software for PIC microcontroller along with the hardware design. The buck and boost converters are designed to interface with the renewable energy source that is PV module. PIC microcontroller is used as a digital controller, which senses the PV electric signal for maximum power using sensors and output voltage of the dc-dc converter and according to that switching pulse is generated for the switching of MOSFET. The implementation of proposed system is based on learning platform of Proteus virtual system modeling (VSM and the experimental results are presented.

In-flight scalar calibration and characterisation of the Swarm magnetometry package

DEFF Research Database (Denmark)

Tøffner-Clausen, Lars; Lesur, Vincent; Olsen, Nils

2016-01-01

of magnetometers is demonstrated, confirming the high performance of these instruments. The results presented here, including the characterisation of a Sun-driven disturbance field, form the basis of the correction of the magnetic vector measurements from Swarm which is applied to the Swarm Level 1b magnetic data.......We present the in-flight scalar calibration and characterisation of the Swarm magnetometry package consisting of the absolute scalar magnetometer, the vector magnetometer, and the spacecraft structure supporting the instruments. A significant improvement in the scalar residuals between the pairs...

Preparation and characterisation of magnetic nanostructured samples for inelastic neutron scattering experiments

Energy Technology Data Exchange (ETDEWEB)

Kreuzpaintner, Wolfgang

2010-06-22

Recent advances in thin-film structuring techniques have generated significant interest in the dynamics of spin waves in magnetic nanostructures and the possible use of inelastic neutron scattering (INS) for their investigation. This thesis describes the design and implementation, at GKSS Research Centre, of equipment for preparation of large and laterally submicron and nanometre structured magnetic samples for such future INS experiments. After a brief resume on spin waves in nanostructures, the development work on new purpose-designed equipment, including high vacuum (HV) argon ion beam milling and ultra high vacuum (UHV) e-beam evaporation setups, is described. Ni nanodot as well as Ni and novel Gd nanowire samples were prepared using combinations of sputter deposition, laser interference lithography, argon ion beam milling, e-beam evaporation and self organisation techniques. With reference to sample preparation, epitaxial growth studies for Ni on Si(100) substrate were performed, resulting in the development of a new deposition process, which by thermal tuning allows for the direct epitaxial growth of Ni on Si with unprecedented crystalline quality. The results of various characterisation experiments on the prepared nanostructured samples, including Scanning Electron Microscopy (SEM), microprobe analysis, Atomic and Magnetic Force Microscopy (AFM/MFM), Vibrating Sample Magnetometry (VSM), X-ray Diffraction (XRD) and Reflectivity (XRR), unpolarised and Polarised Neutron Scattering (PNR) and off-specular scattering by X-rays and neutrons using rocking scans and Time-Of-Flight Grazing Incidence Small Angle Neutron Scattering (TOF-GISANS), together with various analysis procedures such as Distorted-Wave Born Approximation (DWBA), are reported. The analysis of a Gd nanowire sample by TOF-GISANS led to a novel evaluation technique which in comparison with single wavelength methods allows portions of reciprocal space to be scanned without changing the angle of

Preparation and characterisation of magnetic nanostructured samples for inelastic neutron scattering experiments

International Nuclear Information System (INIS)

Kreuzpaintner, Wolfgang

2010-01-01

Recent advances in thin-film structuring techniques have generated significant interest in the dynamics of spin waves in magnetic nanostructures and the possible use of inelastic neutron scattering (INS) for their investigation. This thesis describes the design and implementation, at GKSS Research Centre, of equipment for preparation of large and laterally submicron and nanometre structured magnetic samples for such future INS experiments. After a brief resume on spin waves in nanostructures, the development work on new purpose-designed equipment, including high vacuum (HV) argon ion beam milling and ultra high vacuum (UHV) e-beam evaporation setups, is described. Ni nanodot as well as Ni and novel Gd nanowire samples were prepared using combinations of sputter deposition, laser interference lithography, argon ion beam milling, e-beam evaporation and self organisation techniques. With reference to sample preparation, epitaxial growth studies for Ni on Si(100) substrate were performed, resulting in the development of a new deposition process, which by thermal tuning allows for the direct epitaxial growth of Ni on Si with unprecedented crystalline quality. The results of various characterisation experiments on the prepared nanostructured samples, including Scanning Electron Microscopy (SEM), microprobe analysis, Atomic and Magnetic Force Microscopy (AFM/MFM), Vibrating Sample Magnetometry (VSM), X-ray Diffraction (XRD) and Reflectivity (XRR), unpolarised and Polarised Neutron Scattering (PNR) and off-specular scattering by X-rays and neutrons using rocking scans and Time-Of-Flight Grazing Incidence Small Angle Neutron Scattering (TOF-GISANS), together with various analysis procedures such as Distorted-Wave Born Approximation (DWBA), are reported. The analysis of a Gd nanowire sample by TOF-GISANS led to a novel evaluation technique which in comparison with single wavelength methods allows portions of reciprocal space to be scanned without changing the angle of

Experimental Investigation of the Coprecipitation Method: An Approach to Obtain Magnetite and Maghemite Nanoparticles with Improved Properties

Directory of Open Access Journals (Sweden)

Wilson Sacchi Peternele

2014-01-01

Full Text Available Iron oxides that exhibit magnetic properties have been widely studied not only from an academic standpoint, but also for numerous applications in different fields of knowledge, such as biomedical and technological research. In this work, magnetite and maghemite nanoparticles were synthesized by chemical coprecipitation of FeCl2·4H2O and FeCl3·6H2O (proportion of 1 : 2 in three different cases using two bases (sodium hydroxide and hydroxide ammonium as precipitants. The chemical coprecipitation method was selected for its simplicity, convenience, reproducibility, and low cost in the use of glassware. The nanostructured materials were characterized by transmission electron microscopy (TEM, X-ray diffraction (XRD and magnetometry (VSM. The objective of this work is to study the variation in the morphological characteristics and physical properties of nanoparticles magnetic as a function of the different production processes. As observed by TEM, the materials obtained from the precipitating agent NH4OH are more uniform than those obtained with NaOH. From XRD pattern analysis, it appears that the obtained materials correspond to magnetite and maghemite and, from magnetometry VSM analysis, show high magnetization as a function of the magnetic field at room temperature, indicating that these materials are superparamagnetic.

Interfacial Dzyaloshinskii-Moriya interaction sign in Ir/Co2FeAl systems investigated by Brillouin light scattering

Science.gov (United States)

Belmeguenai, M.; Gabor, M. S.; Roussigné, Y.; Petrisor, T.; Mos, R. B.; Stashkevich, A.; Chérif, S. M.; Tiusan, C.

2018-02-01

C o2FeAl (CFA) ultrathin films, of various thicknesses (0.9 nm ≤tCFA≤1.8 nm ), have been grown by sputtering on Si substrates, using Ir as a buffer layer. The magnetic properties of these structures have been studied by vibrating sample magnetometry (VSM), miscrostrip ferromagnetic resonance (MS-FMR), and Brillouin light scattering (BLS) in the Damon-Eshbach geometry. VSM characterizations show that films are mostly in-plane magnetized and the saturating field perpendicular to the film plane increases with decreasing CFA thickness suggesting the existence of a perpendicular interface anisotropy. The presence of a magnetic dead layer of 0.44 nm has been detected by VSM. The MS-FMR with the magnetic field applied perpendicularly to the film plane has been used to determine the gyromagnetic factor. The BLS measurements reveal a pronounced nonreciprocal spin wave propagation, due to the interfacial Dzyaloshinskii-Moriya interaction (DMI) induced by the Ir interface with CFA, which increases with decreasing CFA thickness. The DMI sign has been found to be the same (negative) as that of Pt/Co, in contrast to the ab initio calculation on Ir/Co, where it is found to be positive. The thickness dependence of the effective DMI constant shows the existence of two regimes similarly to that of the perpendicular anisotropy constant. The surface DMI constant Ds was estimated to be -0.37 pJ /m for the thickest samples, where a linear thickness dependence of the effective DMI constant has been observed.

Micro friction stir lap welding of AISI 430 ferritic stainless steel: a study on the mechanical properties, microstructure, texture and magnetic properties

Science.gov (United States)

Mostaan, Hossein; Safari, Mehdi; Bakhtiari, Arash

2018-04-01

In this study, the effect of friction stir welding of AISI 430 (X6Cr17, material number 1.4016) ferritic stainless steel is examined. Two thin sheets with dimensions of 0.4 × 50 × 200 mm3 are joined in lap configuration. Optical microscopy and field emission electron microscopy were used in order to microstructural evaluations and fracture analysis, respectively. Tensile test and microhardness measurements are employed in order to study the mechanical behaviors of welds. Also, vibrational sample magnetometry (VSM) is employed for characterizing magnetic properties of welded samples. Texture analysis is carried out in order to clarify the change mechanism of magnetic properties in the welded area. The results show that AISI 430 sheets are successfully joined considering both, the appearance of the welding bead and the strength of the welded joint. It is found that by friction stir welding of AISI 430 sheets, texture components with easy axes magnetization have been replaced by texture components with harder magnetization axes. VSM analysis showed that friction stir welding leads to increase in residual induction (Br) and coercivity (Hc). This increase is attributed to the grain refining due the friction stir welding and formation of texture components with harder axes of magnetizations.

Preparation and properties of multifunctional Fe-C-Y2O3:Eu3+ nanocomposites

International Nuclear Information System (INIS)

Yang Jingxing; Yang Xuwei; Yang Hua

2012-01-01

Highlights: ► Multifunctional Fe/Fe 3 O 4 -Y 2 O 3 : Eu nanocomposites were prepared by a solvothermal method. ► Their structure, magnetic and luminescent properties were characterized by XRD, SEM, TEM, excitation and emission spectra and vibration sample magnetometry (VSM). ► It is shown that the nanocomposites exhibit high saturation magnetization and strong red emission under UV-light. - Abstract: Multifunctional Fe-C-Y 2 O 3 :Eu 3+ nanocomposites were prepared by the solvo thermal method, and their structure, magnetic and luminescent properties were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and scanning electron microscope (SEM). Results show that the nanocomposites are spherical with a mean diameter of 700 nm and there are high special saturation magnetization (47.4 emu/g) and strong red emission under UV-light. Even dispersed in water solution, the nanocomposites also exhibit a strong red emission under ultraviolet light radiation, and it could be manipulated using an external magnet. Thus it looks promising for application in biomedicine field, especially in drug targeting and fluorescence label. And we also discussed the effect of the electron transfer process between the Fe magnetic core and Y 2 O 3 :Eu 3+ shell.

Mercury's Surface Magnetic Field Determined from Proton-Reflection Magnetometry

Science.gov (United States)

Winslow, Reka M.; Johnson, Catherine L.; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Lillis, Robert J.; Korth, Haje; Slavin, James A.; Solomon, Sean C.; Zurbuchen, Thomas H.;

Magnetic Properties of Fe(001) Thin Films on GaAs(001) Deposited by RF Magnetron Sputtering

International Nuclear Information System (INIS)

Ikeya, Hirokazu; Takahashi, Yutaka; Inaba, Nobuyuki; Kirino, Fumiyoshi; Ohtake, Mitsuru; Futamoto, Masaaki

2011-01-01

Fe thin films, down to 6 nm thick, were prepared on GaAs(001) substrates by RF magnetron sputtering. The x-ray diffraction (XRD) analyses show that the epitaxial thin films of Fe(001) were grown with cube-on-cube orientation on GaAs(001). Magnetic properties were investigated by vibrating sample magnetometry (VSM) and ferromagnetic resonance (FMR) spectroscopy. The magnetization curves obtained by applying in-plane magnetic fields indicate that easy (hard) direction is along [100] ([110]) and the saturation magnetization is close to the bulk values. The in-plane magnetic anisotropy measured by FMR shows four-fold symmetry, as expected for bcc Fe. We did not observe the in-plane uniaxial magnetic anisotropy reported on the MBE-grown Fe films on GaAs substrates.

Magnetite Nanoparticles Coated with Rifampicin and Chlortetracycline for Drug Delivery Applications

International Nuclear Information System (INIS)

Nadejde, Claudia; Ciurlica, Ecaterina Foca-nici; Creanga, Dorina; Carlescu, Aurelian; Badescu, Vasile

2010-01-01

Four types of biocompatible magnetic fluids based on superparamagnetic nanoparticles with Fe 3 O 4 cores were functionalized with antibiotics (rifampicin or chlortetracycline) as potential candidates for in vivo biomedical applications, such as magnetically controlled drug delivery. The synthesis consisted in coprecipitation of iron oxide in basic, as well as in acid medium, followed by the dispersion of the resulted magnetite nanoparticles in aqueous solution containing the antibiotic. The chosen method to prepare the magnetite-core/drug-shell systems avoided intermediate organic coating of the magnetic nanoparticles. Comparative analysis of the rheological features of the aqueous magnetic fluid samples was performed. The structural features of the coated magnetic particles were investigated by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometry (VSM). Good crystallinity and adequate stability in time were evidenced. Drug delivery curves were spectrophotometrically provided.

PAMAM dendrimer-coated iron oxide nanoparticles: synthesis and characterization of different generations

International Nuclear Information System (INIS)

Khodadust, Rouhollah; Unsoy, Gozde; Yalcın, Serap; Gunduz, Gungor; Gunduz, Ufuk

2013-01-01

This study focuses on the synthesis and characterization of different generations (G 0 –G 7 ) of polyamidoamine (PAMAM) dendrimer-coated magnetic nanoparticles (DcMNPs). In this study, superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method. The synthesized nanoparticles were modified with aminopropyltrimethoxysilane for dendrimer coating. Aminosilane-modified MNPs were coated with PAMAM dendrimer. The characterization of synthesized nanoparticles was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering, and vibrating sample magnetometry (VSM) analyses. TEM images demonstrated that the DcMNPs have monodisperse size distribution with an average particle diameter of 16 ± 5 nm. DcMNPs were found to be superparamagnetic through VSM analysis. The synthesis, aminosilane modification, and dendrimer coating of iron oxide nanoparticles were validated by FTIR and XPS analyses. Cellular internalization of nanoparticles was studied by inverted light scattering microscopy, and cytotoxicity was determined by XTT analysis. Results demonstrated that the synthesized DcMNPs, with their functional groups, symmetry perfection, size distribution, improved magnetic properties, and nontoxic characteristics could be suitable nanocarriers for targeted cancer therapy upon loading with various anticancer agents.

Thermogravimetric and Magnetic Studies of the Oxidation and Reduction Reaction of SmCoO3 to Nanostructured Sm2O3 and Co

Science.gov (United States)

Kelly, Brian; Cichocki, Ronald; Poirier, Gerald; Unruh, Karl

The SmCoO3 to nanostructured Sm2O3 and Co oxidation and reduction reaction has been studied by thermogravimetric analysis (TGA) measurements in forming gas (FG) and inert N2 atmospheres, x-ray diffraction (XRD) and vibrating sample magnetometry (VSM). The TGA measurements showed two clearly resolvable reduction processes when heating in FG, from the initial SmCoO3 phase through an intermediate nanostructured mixture of Sm2O3 and CoO when heated to 330°C for several minutes, and then the conversion of CoO to metallic Co when heated above 500°C. These phases were confirmed by XRD and VSM. Similar measurements in N2 yielded little mass change below 900°C and coupled reduction processes at higher temperatures. Isoconversional measurements of the CoO to Co reduction reaction in FG yielded activation energies above 2eV/atom in the nanostructured system. This value is several times larger than those reported in the literature or obtained by similar measurements of bulk mixtures of Sm2O3 and CoO, suggesting the nanostructuring was the source of the large increase in activation energy.

Magnetometry and Ground-Penetrating Radar Studies in the Sihuas Valley, Peru

Science.gov (United States)

Wisnicki, E.; Papadimitrios, K.; Bank, C.

2013-12-01

The Quillcapampa la Antigua site in Peru's Sihuas Valley is a settlement from Peru's Middle Horizon (600-100 A.D.). Archaeological interest in the area stems from the question of whether ancient civilizations were able to have extensive state control of distant groups, or whether state influence occurred through less direct ties (e.g., marriage, religion, or trade). Our geophysical surveys are preliminary to archaeological digging in the area. Ground-penetrating radar and magnetometry attempt to locate areas of interest for focused archaeological excavation, characterize the design of architectural remains and burial mounds in the area, and allow archaeologists to interpret the amount of influence the Wari civilization had on the local residents.

Structure and some magnetic properties of (BiFeO3x-(BaTiO31−x solid solutions prepared by solid-state sintering

Directory of Open Access Journals (Sweden)

Kowal Karol

2015-03-01

Full Text Available This paper presents the results of the study on structure and magnetic properties of the perovskite-type (BiFeO3x-(BaTiO31−x solid solutions. The samples differing in the chemical composition (x = 0.9, 0.8, and 0.7 were produced according to the conventional solid-state sintering method from the mixture of powders. Moreover, three different variants of the fabrication process differing in the temperatures and soaking time were applied. The results of X-ray diffraction (XRD, Mössbauer spectroscopy (MS, and vibrating sample magnetometry (VSM were collected and compared for the set of the investigated materials. The structural transformation from rhombohedral to cubic symmetry was observed for the samples with x = 0.7. With increasing of BaTiO3 concentration Mössbauer spectra become broadened reflecting various configurations of atoms around 57Fe probes. Moreover, gradual decreasing of the average hyperfine magnetic field and macroscopic magnetization were observed with x decreasing.

Structural and magnetic studies of tin doped α-Fe{sub 2}O{sub 3} (α-Sn{sub x}Fe{sub 2-x}O{sub 3}) nanoparticles prepared by microwave assisted synthesis

Energy Technology Data Exchange (ETDEWEB)

Bindu, K.; Nagaraja, H. S., E-mail: hosakoppa@gmail.com [Material Research Laboratory, Department of Physics, National Institute of Technology Karnataka, Surathkal, Srinivasnagar, Mangalore-575 025, Karnataka (India); Chowdhury, P. [Nanomaterials Research Laboratory, Surface Engineering Division, National Aerospace Laboratories, Council of Scientific and Industrial Research, Bangalore-560 017, Karnataka (India); Ajith, K. M. [Computational Physics Laboratory, Department of Physics, National Institute of Technology Karnataka, Surathkal, Srinivasnagar, Mangalore-575 025, Karnataka (India)

2016-05-06

Hematite (α-Fe{sub 2}O{sub 3}) doped with tetravalent ions have potential applications in various fields such as gas sensors, memories, energy storage devices because of their electrical and magnetic properties. Microwave assisted synthesis was used to prepare Tin doped α-Fe{sub 2}O{sub 3} [α-Sn{sub x}Fe{sub 2-x}O{sub 3}]. The structural and morphological studies were investigated using X-ray diffraction (XRD) and Scanning electron microscopy (SEM). XRD patterns revealed that α-Fe{sub 2}O{sub 3} and α-Sn{sub x}Fe{sub 2-x}O{sub 3} were having rhombohedral structure. The compositional study was done by Energy dispersive X-ray Spectroscopy (EDS). The magnetic properties were studied by Vibrating Sample Magnetometry (VSM). Results shows that the prepared samples were found to be antiferromagnetic in nature and the results are discussed in detail.

Growth of large size lithium niobate single crystals of high quality by tilting-mirror-type floating zone method

Energy Technology Data Exchange (ETDEWEB)

Sarker, Abdur Razzaque, E-mail: razzaque_ru2000@yahoo.com [Department of Physics, University of Rajshahi (Bangladesh)

2016-05-15

Large size high quality LiNbO{sub 3} single crystals were grown successfully by tilting-mirror-type floating zone (TMFZ) technique. The grown crystals were characterized by X-ray diffraction, etch pits density measurement, Impedance analysis, Vibrating sample magnetometry (VSM) and UV-Visible spectrometry. The effect of mirror tilting during growth on the structural, electrical, optical properties and defect density of the LiNbO{sub 3} crystals were investigated. It was found that the defect density in the crystals reduced for tilting the mirror in the TMFZ method. The chemical analysis revealed that the grown crystals were of high quality with uniform composition. The single crystals grown by TMFZ method contains no low-angle grain boundaries, indicating that they can be used for high efficiency optoelectronic devices. (author)

Synthesis and properties of the diluted magnetic semiconductor ZnO doped with nickel ions by combustion reaction; Sintese e propriedades do semicondutor magnetico diluido ZnO dopado com ions de niquel por meio da reacao de combustao

Energy Technology Data Exchange (ETDEWEB)

Morais, A.; Torquato, R.A.; Costa, A.C.F.M, E-mail: m.artur@hotmail.com.br [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Departamento de Engenharia de Materiais; Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais

2017-10-01

One of the greatest challenges for the development of the spintronics this creation of materials having semiconductivity and magnetism at above room temperatures, enabling the creation of devices with greater processing speeds. This work aims to synthesize by combustion reaction semiconductor ZnO doped with nickel ions at a concentration of 0.08 mol for applications such as diluted magnetic semiconductor (DMS). The combustion reaction is quite simple and promising in obtaining single-phase materials at the nanoscale. The obtained powder was subjected to the characterizations of X-ray diffraction (XRD), X-ray fluorescence, vibrating sample magnetometry (VSM), and UV-vis spectroscopy. The crystalline material exhibits ZnO crystalline structure and coercive field of 161,36 Oe, showing that the material exhibits the properties of an SMD. (author)

Magnetometry of buried layers—Linear magnetic dichroism and spin detection in angular resolved hard X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Gloskovskii, Andrei; Stryganyuk, Gregory; Fecher, Gerhard H.; Felser, Claudia; Thiess, Sebastian; Schulz-Ritter, Heiko; Drube, Wolfgang; Berner, Götz; Sing, Michael; Claessen, Ralph; Yamamoto, Masafumi

2012-01-01

Highlights: ► Newly commissioned HAXPES instrument at P09 beamline of the PETRA III ring at DESY. ► We report HAXPES studies on buried magnetic nanolayers in a multi-layer sample. ► Linear magnetic dichroism of photoelectrons from buried CoFe–Ir 78 Mn 22 layers. ► Spin-resolved HAXPES measurements on buried magnetic multilayers using Mott detector. - Abstract: The electronic properties of buried magnetic nano-layers were studied using the linear magnetic dichroism in the angular distribution of photoemitted Fe, Co, and Mn 2p electrons from a CoFe–Ir 78 Mn 22 multi-layered sample. The buried layers were probed using hard X-ray photoelectron spectroscopy, HAXPES, at the undulator beamline P09 of the 3rd generation storage ring PETRA III. The results demonstrate that this magnetometry technique can be used as a sensitive element specific probe for magnetic properties suitable for application to buried ferromagnetic and antiferromagnetic magnetic materials and multilayered spintronics devices. Using the same instrument, spin-resolved Fe 2p HAXPES spectra were obtained from the buried layer with good signal quality.

Probing High Temperature Superconductors with Magnetometry in Ultrahigh Magnetic Fields

Energy Technology Data Exchange (ETDEWEB)

Li, Lu [Univ. of Michigan, Ann Arbor, MI (United States)

2017-07-26

The objective of this research is to investigate the high-field magnetic properties of high temperature superconductors, materials that conduct electricity without loss. A technique known as high-resolution torque magnetometry that was developed to directly measure the magnetization of high temperature superconductors. This technique was implemented using the 65 Tesla pulsed magnetic field facility that is part of the National High Magnetic Field Laboratory at Los Alamos National Laboratory. This research addressed unanswered questions about the interplay between magnetism and superconductivity, determine the electronic structure of high temperature superconductors, and shed light on the mechanism of high temperature superconductivity and on potential applications of these materials in areas such as energy generation and power transmission. Further applications of the technology resolve the novel physical phenomena such as correlated topological insulators, and spin liquid state in quantum magnets.

Hydrogenation of FeCoZr-Al2O3 nanocomposites studied by Moessbauer spectroscopy and magnetometry

International Nuclear Information System (INIS)

Saad, A.; Kasiuk, J.; Fedotova, J.; Szilagyi, E.; Przewoznik, J.; Kapusta, Cz.; Marszalek, M.

2009-01-01

Hydrogenation effects on crystalline and magnetic structure of nanocomposites (FeCoZr) x (Al 2 O 3 ) 100-x , 38 ≤ x ≤ 63 at.% are studied by 57 Fe Moessbauer spectroscopy and magnetometry. Variations of local structure, blocking temperature and mean FeCoZr nanoparticles' volume are discussed with respect to (i) composition and (ii) two competing processes-H 2 incorporation and annealing-occurred during treatment in H 2 plasma.

Precision bounds for gradient magnetometry with atomic ensembles

Science.gov (United States)

Apellaniz, Iagoba; Urizar-Lanz, Iñigo; Zimborás, Zoltán; Hyllus, Philipp; Tóth, Géza

2018-05-01

We study gradient magnetometry with an ensemble of atoms with arbitrary spin. We calculate precision bounds for estimating the gradient of the magnetic field based on the quantum Fisher information. For quantum states that are invariant under homogeneous magnetic fields, we need to measure a single observable to estimate the gradient. On the other hand, for states that are sensitive to homogeneous fields, a simultaneous measurement is needed, as the homogeneous field must also be estimated. We prove that for the cases studied in this paper, such a measurement is feasible. We present a method to calculate precision bounds for gradient estimation with a chain of atoms or with two spatially separated atomic ensembles. We also consider a single atomic ensemble with an arbitrary density profile, where the atoms cannot be addressed individually, and which is a very relevant case for experiments. Our model can take into account even correlations between particle positions. While in most of the discussion we consider an ensemble of localized particles that are classical with respect to their spatial degree of freedom, we also discuss the case of gradient metrology with a single Bose-Einstein condensate.

Characterization and magnetic properties of SrTi{sub 1−x}Ni{sub x}O{sub 3} nanoparticles prepared by hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Karaphun, Attaphol [Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Hunpratub, Sitchai; Phokha, Sumalin [Department of Physics, Faculty of Science, Rajabhat Udon Thani University, Udon Thani 41000 (Thailand); Putjuso, Thanin [Rajamangala University of Technology Rattanakosin Wang Klai Kangwon Campus, Prachuap Khiri Khan 77110 (Thailand); Swatsitang, Ekaphan, E-mail: ekaphan@kku.ac.th [Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen 40002 (Thailand)

2017-01-01

SrTi{sub 1−x}Ni{sub x}O{sub 3} (x=0, 0.05, 0.10 and 0.15) nanoparticles were prepared by the hydrothermal method. All as-prepared samples were annealed at 800 °C for 3 h in argon to study the annealing effect on their magnetic properties. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray absorption near edge spectroscopy (XANES), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM) were used to study the crystalline structure, morphology, oxidation state and magnetic properties of samples. XRD results indicate a cubic perovskite structure of all samples with the impurity phase of SrCO{sub 3} in all as-prepared samples and Ni metal in annealed samples of x=0.10 and 0.15. SEM and TEM images confirmed a cubic shape for all samples with decreasing average particle sizes from 136.8±4.7 to 126.2±6.9 nm for annealed samples upon Ni doping. XANES results revealed the existence of Ni metal in sample of x=0.05 with the oxidation state of +2 for Ni ion in a SrTi{sub 0.95}Ni{sub 0.05}O{sub 3} sample. XPS results indicated the promotion of oxygen vacancies. VSM results revealed a paramagnetic behavior at room temperature of all as-prepared samples. Ni-doped samples exhibited ferromagnetic behavior after annealing in argon with the Curie temperature (T{sub C}) above 380 K for a sample with x=0.05 as shown by field cooling (FC) and zero-field cooling (ZFC) measurements. The room temperature ferromagnetism (RT-FM) of ferromagnetic samples was suggested to be originated from Ni metal and F-center exchange (FCE) mechanism due to the promotion of oxygen vacancies in the perovskite structure.

Degradation of magnetite nanoparticles in biomimetic media

Energy Technology Data Exchange (ETDEWEB)

Briceño, Sarah; Hernandez, Ana C.; Sojo, Juan [Instituto Venezolano de Investigaciones Científicas (IVIC), Laboratorio de Materiales, Centro de Ingeniería de Materiales y Nanotecnología (Venezuela, Bolivarian Republic of); Lascano, Luis [Dpto. Física, Escuela Politécnica Nacional (Ecuador); Gonzalez, Gema, E-mail: gemagonz@ivic.gob.ve, E-mail: gema.gonzalez@epn.edu.ec [Escuela Nacional Politécnica (Ecuador)

2017-04-15

Magnetic nanoparticles (NPs) of magnetite Fe{sub 3}O{sub 4} obtained by coprecipitation (COP), thermal decomposition (DT), and commercial sample (CM) have been degraded in similar conditions to physiological medium at pH 4.7 and in simulated body fluid (SBF) at pH 7.4. The formation of the nanoparticles was confirmed by FTIR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In view of medical and environmental applications, the stability of the particles was measured with dynamic light scattering. The degradation processes were followed with atomic absorption spectroscopy (EAA) and TEM. Magnetic measurements were carried out using vibrating sample magnetometry (VSM). Our results revealed that the structural and magnetic properties of the remaining nanoparticles after the degradation process were significantly different to those of the initial suspension. The degradation kinetics is affected by the pH, the coating, and the average particle size of the nanoparticles.

Composition and B-H curve analysis of low carbon steel from Krakatau Steel company using VSM And EDX for magnet design of 13 MeV cyclotron

International Nuclear Information System (INIS)

Taufik; Emy Mulyani; Kusminarto; Slamet Santosa

2012-01-01

Cyclotron is one type of particle accelerator that accelerate particle in circular trajectory, in order to obtain high kinetic energy. One of the main components is the cyclotron magnet system that serves to form a cyclic particle trajectories and made of forged low carbon steel. In the magnet design, the selection of magnetic materials is very important in determining whether cyclotron magnet can operate properly or not and even can be optimal. That is why we need to test samples of magnetic materials from local production in this case two samples of material produced by PT Krakatau Steel (KS). Tests performed include testing of BH curve using VSM (Vibrating Sample Magnetometer) and material composition using EDX (Energy-dispersive X-ray spectroscopy). Obtained BH curve is used as material data in three-dimensional simulation using the Opera 3D with referee to magnetic model of Kirams 13. From this study it can be concluded that the position of the test object to the direction of the magnetic field induction gives different BH curve and the samples obtained from KS has a carbon content which is still high. The lower the carbon content in the iron will produce a better magnetic properties. Material samples analyzed will produce a field that is not optimal when it is used in a 13 MeV cyclotron magnet. (author)

Experimental investigation of the effect of thermal hysteresis in MnFeP1-x Asx materials applied in an AMR device

DEFF Research Database (Denmark)

von Moos, Lars; Nielsen, Kaspar Kirstein; Engelbrecht, Kurt

2012-01-01

The magnetocaloric material series MnFeP1-xAsx, exhibiting a 1st order phase transition are possibly good candidates for magnetic refrigeration devices operating at room temperature (Brück et al., 2005). These materials have intrinsic hysteresis (thermal and magnetic) and the impact...... (AMR) test device (Bahl et al., 2008) with a flat plate regenerator of a single Curie temperature (TC) material. We find that the maximum adiabatic entropy change does not depend on the thermal history of the material, but the peak temperature is shifted 1.5 K for fields up to 1.5 T when measured...... of this on magnetic refrigeration devices has not yet been thoroughly investigated in the literature. Here, the thermal hysteretic magnetocaloric properties are studied using vibrating sample magnetometry (VSM) and how this influences actual refrigeration performance, using an established active magnetic regenerator...

Structure and magnetic properties of Mg0.35Cu0.2Zn0.45Fe2O4 ferrite synthesized by co-precipitation method

Directory of Open Access Journals (Sweden)

Bo Yang

2017-05-01

Full Text Available Mg0.35Cu0.2Zn0.45Fe2O4 nanosize particles have been synthesized by chemical co-precipitation method and characterized by X-ray diffraction (XRD and vibrating sample magnetometry (VSM. The XRD patterns confirmed the single phase spinel structure of the synthesized powder. The average crystallite size of the powder varied from 14 to 55 nm by changing annealing temperature. The activation energy for crystal growth was estimated as about 18.61KJ/mol. With the annealing temperature increasing, saturation magnetization (MS was successively increased while the coercivity (HC was first increased, passed through a maximum and then declined. The sintering temperature has significant influence on bulk density, initial permeability and Curie temperature of Mg0.35Cu0.2Zn0.45Fe2O4 ferrite.

Chiral cavity ring down polarimetry: Chirality and magnetometry measurements using signal reversals.

Science.gov (United States)

Bougas, Lykourgos; Sofikitis, Dimitris; Katsoprinakis, Georgios E; Spiliotis, Alexandros K; Tzallas, Paraskevas; Loppinet, Benoit; Rakitzis, T Peter

2015-09-14

We present the theory and experimental details for chiral-cavity-ring-down polarimetry and magnetometry, based on ring cavities supporting counterpropagating laser beams. The optical-rotation symmetry is broken by the presence of both chiral and Faraday birefringence, giving rise to signal reversals which allow rapid background subtractions. We present the measurement of the specific rotation at 800 nm of vapors of α-pinene, 2-butanol, and α-phellandrene, the measurement of optical rotation of sucrose solutions in a flow cell, the measurement of the Verdet constant of fused silica, and measurements and theoretical treatment of evanescent-wave optical rotation at a prism surface. Therefore, these signal-enhancing and signal-reversing methods open the way for ultrasensitive polarimetry measurements in gases, liquids and solids, and at surfaces.

Chiral cavity ring down polarimetry: Chirality and magnetometry measurements using signal reversals

International Nuclear Information System (INIS)

Bougas, Lykourgos; Sofikitis, Dimitris; Katsoprinakis, Georgios E.; Spiliotis, Alexandros K.; Rakitzis, T. Peter; Tzallas, Paraskevas; Loppinet, Benoit

2015-01-01

We present the theory and experimental details for chiral-cavity-ring-down polarimetry and magnetometry, based on ring cavities supporting counterpropagating laser beams. The optical-rotation symmetry is broken by the presence of both chiral and Faraday birefringence, giving rise to signal reversals which allow rapid background subtractions. We present the measurement of the specific rotation at 800 nm of vapors of α-pinene, 2-butanol, and α-phellandrene, the measurement of optical rotation of sucrose solutions in a flow cell, the measurement of the Verdet constant of fused silica, and measurements and theoretical treatment of evanescent-wave optical rotation at a prism surface. Therefore, these signal-enhancing and signal-reversing methods open the way for ultrasensitive polarimetry measurements in gases, liquids and solids, and at surfaces

Structural characterization and electron density distribution studies of (La{sub 0.8}Ca{sub 0.2})(Cr{sub 0.9−x}Co{sub 0.1}Mn{sub x})O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Saravanan, R. [Research Centre and Post Graduate Department of physics, The Madura College, Madurai 625011 (India); Thenmozhi, N., E-mail: thenmozhi.n6@gmail.com [PG and Research Department of Physics, NMSSVN College, Nagamalai, Madurai 625019 (India); Fu, Yen-Pei [Department of materials Science and Engineering, National Dong-Hwa University, Shou-Feng, Hualien 974, Taiwan (China)

2016-07-15

The doped lanthanum chromite (La{sub 0.8}Ca{sub 0.2})(Cr{sub 0.9−x}Co{sub 0.1}Mn{sub x})O{sub 3} (x=0.03, 0.06, 0.09 and 0.12) were synthesized by solid state reaction technique. The samples have been characterized by X-ray diffraction for structural and charge density analysis. XRD data show that the grown samples are orthorhombic in structure with single phase. The spatial charge density distribution in the unit cell for the synthesized samples has been studied using maximum entropy method. Further, the samples were analyzed by UV–visible spectrometry for optical properties and scanning electron microscopy for surface morphology. From the optical data, it was found that the direct band gap of the samples range from 2.27 to 2.46 eV. The samples were also investigated by vibrating sample magnetometry for magnetic properties. From VSM data, it is inferred that all the samples in this series are found to be predominantly antiferromagnetic in nature. Since the doped lanthanum chromites have good mechanical properties and electrical conductivity at high temperature, these materials are used in solid oxide fuel cells (SOFC).

Integrated evaluation of the geology, aero gamma spectrometry and aero magnetometry of the Sul-Riograndense Shield, southernmost Brazil

Energy Technology Data Exchange (ETDEWEB)

Hartmann, Leo A.; Savian, Jairo F., E-mail: leo.hartmann@ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRS), Porto Alegre, RS (Brazil). Instituto de Geociencias; Lopes, William R. [Servico Geologico do Brasil (CPRM), Porto Alegre, RS (Brazil). Gerencia de Geologia e Mineracao

2016-03-15

An integrated evaluation of geology, aero gamma spectrometry and aero magnetometry of the Sul-Riograndense Shield is permitted by the advanced stage of understanding of the geology and geochronology of the southern Brazilian Shield and a 2010 airborne geophysical survey. Gamma rays are registered from the rocks near the surface and thus describe the distribution of major units in the shield, such as the Pelotas batholith, the juvenile São Gabriel terrane, the granulite-amphibolite facies Taquarembo terrane and the numerous granite intrusions in the foreland. Major structures are also observed, e.g., the Dorsal de Cangucu shear. Magnetic signals register near surface crustal compositions (analytic signal) and total crust composition (total magnetic signal), so their variation as measured indicates either shallow or whole crustal structures. The Cacapava shear is outstanding on the images as is the magnetic low along the N-S central portion of the shield. These integrated observations lead to the deepening of the understanding of the largest and even detailed structures of the Sul-Riograndense Shield, some to be correlated to field geology in future studies. Most significant is the presence of different provinces and their limits depending on the method used for data acquisition - geology, aero gamma spectrometry or aero magnetometry. (author)

Application of SQUIDs to low temperature and high magnetic field measurements—Ultra low noise torque magnetometry

Science.gov (United States)

Arnold, F.; Naumann, M.; Lühmann, Th.; Mackenzie, A. P.; Hassinger, E.

2018-02-01

Torque magnetometry is a key method to measure the magnetic anisotropy and quantum oscillations in metals. In order to resolve quantum oscillations in sub-millimeter sized samples, piezo-electric micro-cantilevers were introduced. In the case of strongly correlated metals with large Fermi surfaces and high cyclotron masses, magnetic torque resolving powers in excess of 104 are required at temperatures well below 1 K and magnetic fields beyond 10 T. Here, we present a new broadband read-out scheme for piezo-electric micro-cantilevers via Wheatstone-type resistance measurements in magnetic fields up to 15 T and temperatures down to 200 mK. By using a two-stage superconducting-quantum interference device as a null detector of a cold Wheatstone bridge, we were able to achieve a magnetic moment resolution of Δm = 4 × 10-15 J/T at maximal field and 700 mK, outperforming conventional magnetometers by at least one order of magnitude in this temperature and magnetic field range. Exemplary de Haas-van Alphen measurement of a newly grown delafossite, PdRhO2, was used to show the superior performance of our setup.

Correlating structural, magnetic, and luminescence properties with the cation distribution of Co{sub 0.5}Zn{sub 0.5+x}Fe{sub 2–x}O{sub 4} nanoferrite

Energy Technology Data Exchange (ETDEWEB)

Wahba, Adel Maher, E-mail: a_m_wahba@yahoo.co.uk [Department of Engineering Physics and Mathematics, Faculty of Engineering, Tanta University (Egypt); Mohamed, Mohamed Bakr [Ain shams University, Faculty of Science, Physics Department, Cairo (Egypt); Imam, N.G. [Experimental Physics Department, Nuclear Research Center, Atomic Energy Authority, 13759 Cairo (Egypt)

2016-06-15

Structural, magnetic, and luminescence properties have been investigated for Co{sub 0.5}Zn{sub 0.5+x}Fe{sub 2−x}O{sub 4} nanoferrite (0.0≤x≤0.4, with a step increment of 0.1) prepared by citrate autocombustion method. X-ray diffraction (XRD) patterns and Fourier-transform infrared (FTIR) spectra proved the formation of a pure cubic spinel phase for all AP samples. Although the ionic radius of Zn{sup 2+} is larger than that of either Fe{sup 3+} or Co{sup 2+}, Rietveld analysis showed that the lattice parameter mostly decreases with increasing Zn substitution. The crystallite size of AP samples decreases gradually with increasing Zn substitution from 16 to 10 nm, which is confirmed with high-resolution (HRTEM) micrographs. Magnetic parameters such as saturation magnetization, coercivity, and remanent field obtained from vibrating sample magnetometry (VSM) revealed a strong dependence on the cation distribution being proposed according to the experimental data of XRD, FTIR, and VSM. The cation distribution indicated that introduced nonstoichiometry is compensated by oxidizing Co{sup 2+} into Co{sup 3+}, which explains the trend of the lattice parameter with increasing x. The distribution of Fe{sup 3+} ions between octahedral and tetrahedral sites was further confirmed by photoluminescence (PL) emission spectra. - Highlights: • Co{sub 0.5}Zn{sub 0.5+x}Fe{sub 2−x}O{sub 4} nanoferrites have been prepared by citrate-precursor method. • XRD peaks and IR bands confirmed pure spinel structure for all samples. • Structural, magnetic, and optical properties depend on the cation distribution. • A cation distribution was proposed based on the experimental data.

Thermal and magnetic behavior of Angustifolia Kunth bamboo fibers covered with Fe3O4 particles

International Nuclear Information System (INIS)

Calvo, S.; Arias, N.P.; Giraldo, O.; Rosales-Rivera, A.; Moscoso, O.

2012-01-01

Several Angustifolia Kunth bamboo fibers, which have been previously treated with an alkaline solution, were coated with magnetite particles. The coating of the fibers was achieved by an in-situ co-precipitation method with Fe 2+ and Fe 3+ in NaOH or NH 4 OH. The fibers were evaluated by chemical analysis using atomic absorption (A.A.) technique, structural characterization by X-ray diffraction (XRD), thermal stability with thermo-gravimetric analysis (TGA) in nitrogen at temperature range between 23 °C and 800 °C and magnetic behavior using vibrating sample magnetometry (VSM) applying a magnetic field between -27 KOe and 27 KOe at room temperature. We found that the thermal stability and magnetization depend of the synthesis method used to cover the Angustifolia Kunth bamboo fibers. In addition, an improved magnetic response was observed when NaOH solution is used to generate the magnetite coating on the fiber surface.

Single Additive Enables 3D Printing of Highly Loaded Iron Oxide Suspensions.

Science.gov (United States)

Hodaei, Amin; Akhlaghi, Omid; Khani, Navid; Aytas, Tunahan; Sezer, Dilek; Tatli, Buse; Menceloglu, Yusuf Z; Koc, Bahattin; Akbulut, Ozge

2018-03-21

A single additive, a grafted copolymer, is designed to ensure the stability of suspensions of highly loaded iron oxide nanoparticles (IOPs) and to facilitate three-dimensional (3D) printing of these suspensions in the filament form. This poly (ethylene glycol)-grafted copolymer of N-[3(dimethylamino)propyl]methacrylamide and acrylic acid harnesses both electrostatic and steric repulsion to realize an optimum formulation for 3D printing. When used at 1.15 wt % (by the weight of IOPs), the suspension attains ∼81 wt % solid loading-96% of the theoretical limit as calculated by the Krieger-Dougherty equation. Rectangular, thick-walled toroidal, and thin-walled toroidal magnetic cores and a porous lattice structure are fabricated to demonstrate the utilization of this suspension as an ink for 3D printing. The electrical and magnetic properties of the magnetic cores are characterized through impedance spectroscopy (IS) and vibrating sample magnetometry (VSM), respectively. The IS indicates the possibility of utilizing wire-wound 3D printed cores as the inductive coils. The VSM verifies that the magnetic properties of IOPs before and after the ink formulation are kept almost unchanged because of the low dosage of the additive. This particle-targeted approach for the formulation of 3D printing inks allows embodiment of a fully aqueous system with utmost target material content.

Preparation and investigation of structural properties of magnetic diatomite nanocomposites formed with different iron content

Energy Technology Data Exchange (ETDEWEB)

Yusan, Sabriye, E-mail: sabriye.doyurum@ege.edu.tr [Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir (Turkey); Korzhynbayeva, Kuralay [Al-Farabi Kazakh National University, Faculty of Chemistry and Chemical Technology, 050040 Almaty (Kazakhstan); Aytas, Sule [Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir (Turkey); Tazhibayeva, Sagdat; Musabekov, Kuanyshbek [Al-Farabi Kazakh National University, Faculty of Chemistry and Chemical Technology, 050040 Almaty (Kazakhstan)

2014-09-01

Highlights: • Magnetic diatomite nanocomposites were generated by partial reduction co-precipitation method. • VSM results showed that nanocomposites have superparamagnetic behaviour. • The nanocomposites were also characterized by XRD, FTIR, SEM, DTA/TGA and BET. - Abstract: Magnetic diatomite nanocomposites (MDNC) were synthesized successfully by partial reduction co-precipitation method from iron salt solution at different concentrations and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal analyses (DTA/TGA), vibrating sample magnetometry (VSM) and surface area measurements (BET). The XRD pattern of magnetic diatomite nanocomposites is face centered cubic with an average diameter of 4.67, 4.11 and 4. 82 nm as MDNC-1, MDNC-2 and MDNC-3, respectively. The saturation magnetization values for magnetic diatomite composites (diatomite/Fe ratio 1:1.5, 1:2.0 and 1:3.0) were found to be 13.81, 13.37 and 16.42 emu/g, respectively. By FT-IR spectra it was found that the main features of the silica framework were maintained after magnetite incorporation and some peak intensities were increased with magnetite loading. The cell parameter increase and the surface area decrease with increase in Fe content, observed by N{sub 2} adsorption–desorption technique, were considered as evidence of metal concentration effect in the synthesis procedure.

Hydrogenation of FeCoZr-Al{sub 2}O{sub 3} nanocomposites studied by Moessbauer spectroscopy and magnetometry

Energy Technology Data Exchange (ETDEWEB)

Saad, A. [Al-Balqa Applied University, Appl. Science Department (Jordan); Kasiuk, J.; Fedotova, J., E-mail: Julia@hep.by [NC PHEP BSU (Belarus); Szilagyi, E. [KFKI Research Institute for Particle and Nuclear Physics (Hungary); Przewoznik, J.; Kapusta, Cz. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science (Poland); Marszalek, M. [Niewodniczanski Institute of Nuclear Physics PAN (Poland)

2009-02-15

Hydrogenation effects on crystalline and magnetic structure of nanocomposites (FeCoZr){sub x}(Al{sub 2}O{sub 3}){sub 100-x}, 38 {<=} x {<=} 63 at.% are studied by {sup 57}Fe Moessbauer spectroscopy and magnetometry. Variations of local structure, blocking temperature and mean FeCoZr nanoparticles' volume are discussed with respect to (i) composition and (ii) two competing processes-H{sub 2} incorporation and annealing-occurred during treatment in H{sub 2} plasma.

Magnetic behaviour of arrays of Ni nanowires by electrodeposition into self-aligned titania nanotubes

International Nuclear Information System (INIS)

Prida, V.M.; Hernandez-Velez, M.; Cervera, M.; Pirota, K.; Sanz, R.; Navas, D.; Asenjo, A.; Aranda, P.; Ruiz-Hitzky, E.; Batallan, F.; Vazquez, M.; Hernando, B.; Menendez, A.; Bordel, N.; Pereiro, R.

2005-01-01

Arrays of Ni nanowires electrodeposited into self-aligned and randomly disordered titania nanotube arrays grown by anodization process are investigated by X-ray diffraction, SEM, rf-GDOES and VSM magnetometry. The titania nanotube outer diameter is about 160 nm, wall thickness ranging from 60 to 70 nm and 300 nm in depth. The so-obtained Ni nanowires reach above 100 nm diameter and 240 nm length, giving rise to coercive fields of 98 and 200 Oe in the perpendicular or parallel to the nanowires axis hysteresis loops, respectively. The formation of magnetic vortex domain states is also discussed

Tutorial: Magnetic resonance with nitrogen-vacancy centers in diamond—microwave engineering, materials science, and magnetometry

Science.gov (United States)

Abe, Eisuke; Sasaki, Kento

2018-04-01

This tutorial article provides a concise and pedagogical overview on negatively charged nitrogen-vacancy (NV) centers in diamond. The research on the NV centers has attracted enormous attention for its application to quantum sensing, encompassing the areas of not only physics and applied physics but also chemistry, biology, and life sciences. Nonetheless, its key technical aspects can be understood from the viewpoint of magnetic resonance. We focus on three facets of this ever-expanding research field, to which our viewpoint is especially relevant: microwave engineering, materials science, and magnetometry. In explaining these aspects, we provide a technical basis and up-to-date technologies for research on the NV centers.

Tuning of Magnetic Anisotropy in Hexairon(III) Rings by Host-Guest Interactions: An Investigation by High-Field Torque Magnetometry.

Science.gov (United States)

Cornia; Affronte; Jansen; Abbati; Gatteschi

1999-08-01

Full chemical control of magnetic anisotropy in hexairon(III) rings can be achieved by varying the size of the guest alkali metal ion. Dramatically different anisotropies characterize the Li(I) and Na(I) complexes of [Fe(6)(OMe)(12)(L)(6)] (L=1,3-propanedione derivatives; a schematic representation of the Li(I) complex is shown), as revealed by high-field torque magnetometry-Iron: (g), oxygen: o, carbon: o, Li(+): plus sign in circle.

Magnetic nanoparticles modified with polyfuran for the extraction of polycyclic aromatic hydrocarbons prior to their determination by gas chromatography

International Nuclear Information System (INIS)

Amiri, Amirhassan; Baghayeri, Mehdi; Kashmari, Milad

2016-01-01

We describe magnetite nanoparticles modified with polyfuran (PFu/Fe 3 O 4 ) and their use as adsorbents for the solid-phase extraction of the polycyclic aromatic hydrocarbons (PAHs) naphthalene, fluorene and anthracene from water and urine samples. The PFu/Fe 3 O 4 nanocomposite was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and vibrating sample magnetometry (VSM). The adsorbent was magnetically separated from the sample, extracted with dichloromethane, and the extracts were submitted to gas chromatographic analysis with flame ionization detection. The amount of adsorbent, adsorption and desorption time, salt addition and desorption solvent were optimized. The method displays detection limits (at an S/N ratio of 3) in the range from 5 to 20 pg mL −1 , and the limits of quantification (at an S/N ratio of 10) are between 20 and 50 pg mL −1 . Relative standard deviations (RSDs) for intra- and inter-day precision are 4.1–5.6, and 5.3–6.5 %, respectively. The feasibility of the method was demonstrated by extracting and determining PAHs in (spiked) real water and urine samples. (author)

Growth and magnetic study of sputtered Fe/Al multilayers

International Nuclear Information System (INIS)

Cherif, S.M.; Bouziane, K.; Roussigne, Y.; Al-Busaidy, M.

2007-01-01

Brillouin light scattering (BLS) and vibrating sample magnetometry (VSM) were used to study the effect of interfacial intermixing and microstructure on the magnetic properties of DC magnetron sputtered Fe/Al multilayers (MLs) on Si(1 0 0) substrate. Three samples with nominal composition [Al (4 nm)/Fe (3.7 nm)] x18 and deposited under different negative DC bias voltages (V b = -50, -200 and -400 V) have been investigated. The X-ray diffraction results indicate that the FeAl MLs have a poor crystallinity with no evidence of the absence of B2 phase. The grazing X-ray reflectivity results suggest that the interfacial roughness and intermixing were gradually reduced from 0.7 to 0.5 nm (±0.05 nm) by increasing V b from -50 to -400 V. The magnetization measurements demonstrate the presence of in-plane uniaxial anisotropy and magnetically dead interfacial layers. The BLS results reveal spin-wave surface modes whose frequencies also depend on the applied V b . The same trend upon V b was observed for the perpendicular and in-plane anisotropies

Growth and magnetic study of sputtered Fe/Al multilayers

Energy Technology Data Exchange (ETDEWEB)

Cherif, S.M. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France); Bouziane, K. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France) and Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)]. E-mail: bouzi@squ.edu.om; Roussigne, Y. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France); Al-Busaidy, M. [Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)

2007-03-15

Brillouin light scattering (BLS) and vibrating sample magnetometry (VSM) were used to study the effect of interfacial intermixing and microstructure on the magnetic properties of DC magnetron sputtered Fe/Al multilayers (MLs) on Si(1 0 0) substrate. Three samples with nominal composition [Al (4 nm)/Fe (3.7 nm)]{sub x18} and deposited under different negative DC bias voltages (V {sub b} = -50, -200 and -400 V) have been investigated. The X-ray diffraction results indicate that the FeAl MLs have a poor crystallinity with no evidence of the absence of B2 phase. The grazing X-ray reflectivity results suggest that the interfacial roughness and intermixing were gradually reduced from 0.7 to 0.5 nm ({+-}0.05 nm) by increasing V {sub b} from -50 to -400 V. The magnetization measurements demonstrate the presence of in-plane uniaxial anisotropy and magnetically dead interfacial layers. The BLS results reveal spin-wave surface modes whose frequencies also depend on the applied V{sub b}. The same trend upon V {sub b} was observed for the perpendicular and in-plane anisotropies.

Volumetric localization of somatosensory cortex in children using synthetic aperture magnetometry

International Nuclear Information System (INIS)

Xiang, Jing; Holowka, Stephanie; Chuang, Sylvester; Sharma, Rohit; Hunjan, Amrita; Otsubo, Hiroshi

2003-01-01

Magnetic signal from the human brain can be measured noninvasively by using magnetoencephalography (MEG). This study was designed to localize and reconstruct the neuromagnetic activity in the somatosensory cortex in children Twenty children were studied using a 151-channel MEG system with electrical stimulation applied to median nerves. Data were analyzed using synthetic aperture magnetometry (SAM). A clear deflection (M1) was clearly identified in 18 children (90%, 18/20). Two frequency bands, 30-60 Hz and 60-120 Hz, were found to be related to somatosensory cortex. Magnetic activity was localized in the posterior bank of the central sulcus in 16 children. The extent of the reconstructed neuromagnetic activity of the left hemisphere was significantly larger than that of the right hemisphere (P<0.01). Somatosensory cortex was accurately localized by using SAM. The extent of the reconstructed neuromagnetic activity suggested that the left hemisphere was the dominant side in the somatosensory system in children. We postulate that the volumetric characteristics of the reconstructed neuromagnetic activity are able to indicate the functionality of the brain. (orig.)

Thermal and magnetic behavior of Angustifolia Kunth bamboo fibers covered with Fe{sub 3}O{sub 4} particles

Energy Technology Data Exchange (ETDEWEB)

Calvo, S. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Arias, N.P. [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Departamento de Ingenieria Electrica, Electronica y Computacion, Facultad de Ingenieria y Arquitectura, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Giraldo, O., E-mail: ohggiraldo@hotmail.com [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Rosales-Rivera, A.; Moscoso, O. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia)

2012-08-15

Several Angustifolia Kunth bamboo fibers, which have been previously treated with an alkaline solution, were coated with magnetite particles. The coating of the fibers was achieved by an in-situ co-precipitation method with Fe{sup 2+} and Fe{sup 3+}in NaOH or NH{sub 4}OH. The fibers were evaluated by chemical analysis using atomic absorption (A.A.) technique, structural characterization by X-ray diffraction (XRD), thermal stability with thermo-gravimetric analysis (TGA) in nitrogen at temperature range between 23 Degree-Sign C and 800 Degree-Sign C and magnetic behavior using vibrating sample magnetometry (VSM) applying a magnetic field between -27 KOe and 27 KOe at room temperature. We found that the thermal stability and magnetization depend of the synthesis method used to cover the Angustifolia Kunth bamboo fibers. In addition, an improved magnetic response was observed when NaOH solution is used to generate the magnetite coating on the fiber surface.

Synthesis of highly stable folic acid conjugated magnetite nanoparticles for targeting cancer cells

International Nuclear Information System (INIS)

Mohapatra, S; Mallick, S K; Maiti, T K; Ghosh, S K; Pramanik, P

2007-01-01

A new approach towards the design of folic acid conjugated magnetic nanoparticles for enhancing their site specific intracellular uptake against a folate receptor overexpressing cancer cells is reported. Magnetite nanoparticles were prepared by coprecipitation from an Fe 3+ and Fe 2+ solution followed by surface modification with 2-carboxyethyl phosphonic acid to form carboxyl group terminated nanoparticles. Then folic acid and fluorescein isothiocyanate (FITC) were conjugated with carboxylic acid functionalized magnetite nanoparticles using 2,2'-(ethylenedioxy)-bis-ethylamine. These folate-conjugated nanoparticles were characterized in terms of their size by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Surface functional groups and surface composition were analyzed by Fourier transform infrared (FTIR) spectroscopy and x-ray photoelectron spectroscopy (XPS), respectively. Vibration sample magnetometry (VSM) measurements showed the superparamagnetic nature of the particles at room temperature. Folate-conjugated magnetic nanoparticles are noncytotoxic and receptor mediated internalization by HeLa and B16 melanoma F0 cancer cells was confirmed by flow cytometry and confocal microscopy

Influence of PEG Stoichiometry on Structure-Tuned Formation of Self-Assembled Submicron Nickel Particles

Directory of Open Access Journals (Sweden)

Bingxue Pu

2018-01-01

Full Text Available Self-assembled submicron nickel particles were successfully synthesized via the one-step surfactant-assisted solvothermal method. The impact of surfactant and reducing agent stoichiometry is investigated in this manuscript. Different morphologies and structures of Ni particles, including flower-like nanoflakes, hydrangea-like structures, chain structures, sphere-like structures, and hollow structures were prepared through different processing conditions with two parameters such as temperature and time. Based on scanning electron microscopy (SEM, X-ray diffraction (XRD, thermal gravimetric analysis (TGA and vibrating sample magnetometry (VSM, the submicron nickel particles show good saturation magnetization and excellent thermal stabilities with a possible growth mechanism for the variety of the structure-tuned formation. Importantly, the microwave absorption properties of the submicron nickel particles were studied. The lowest reflection loss of Ni-P9/T200/H15 with a thin layer thickness of 1.7 mm can reach −42.6 dB at 17.3 GHz.

Mechanosynthesis of MFe2O4 (M = Co, Ni, and Zn Magnetic Nanoparticles for Pb Removal from Aqueous Solution

Directory of Open Access Journals (Sweden)

America R. Vazquez-Olmos

2016-01-01

Full Text Available Adsorption of Pb(II from aqueous solution using MFe2O4 nanoferrites (M = Co, Ni, and Zn was studied. Nanoferrite samples were prepared via the mechanochemical method and were characterized by X-ray powder diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, micro-Raman, and vibrating sample magnetometry (VSM. XRD analysis confirms the formation of pure single phases of cubic ferrites with average crystallite sizes of 23.8, 19.4, and 19.2 nm for CoFe2O4, NiFe2O4, and ZnFe2O4, respectively. Only NiFe2O4 and ZnFe2O4 samples show superparamagnetic behavior at room temperature, whereas CoFe2O4 is ferromagnetic. Kinetics and isotherm adsorption studies for adsorption of Pb(II were carried out. A pseudo-second-order kinetic describes the sorption behavior. The experimental data of the isotherms were well fitted to the Langmuir isotherm model. The maximum adsorption capacity of Pb(II on the nanoferrites was found to be 20.58, 17.76, and 9.34 mg·g−1 for M = Co, Ni, and Zn, respectively.

Investigation of the field dependent spin structure of exchange coupled magnetic heterostructures

International Nuclear Information System (INIS)

Gurieva, Tatiana

2016-05-01

This thesis describes the investigation of the field dependent magnetic spin structure of an antiferromagnetically (AF) coupled Fe/Cr heterostructure sandwiched between a hardmagnetic FePt buffer layer and a softmagnetic Fe top layer. The depth-resolved experimental studies of this system were performed via Magneto-optical Kerr effect (MOKE), Vibrating Sample Magnetometry (VSM) and various measuring methods based on nuclear resonant scattering (NRS) technique. Nucleation and evolution of the magnetic spiral structure in the AF coupled Fe/Cr multilayer structure in an azimuthally rotating external magnetic field were observed using NRS. During the experiment a number of time-dependent magnetic side effects (magnetic after-effect, domain-wall creep effect) caused by the non-ideal structure of a real sample were observed and later explained. Creation of the magnetic spiral structure in rotating external magnetic field was simulated using a one-dimensional micromagnetic model.The cross-sectional magnetic X-ray diffraction technique was conceived and is theoretically described in the present work. This method allows to determine the magnetization state of an individual layer in the magnetic heterostructure. It is also applicable in studies of the magnetic structure of tiny samples where conventional x-ray reflectometry fails.

Tunable photoluminescence and magnetic properties of Dy(3+) and Eu(3+) doped GdVO4 multifunctional phosphors.

Science.gov (United States)

Liu, Yanxia; Liu, Guixia; Dong, Xiangting; Wang, Jinxian; Yu, Wensheng

2015-10-28

A series of Dy(3+) or/and Eu(3+) doped GdVO4 phosphors were successfully prepared by a simple hydrothermal method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectrometry (EDS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). The results indicate that the as-prepared samples are pure tetragonal phase GdVO4, taking on nanoparticles with an average size of 45 nm. Under ultraviolet (UV) light excitation, the individual Dy(3+) or Eu(3+) ion activated GdVO4 phosphors exhibit excellent emission properties in their respective regions. The mechanism of energy transfer from the VO4(3-) group and the charge transfer band (CTB) to Dy(3+) and Eu(3+) ions is proposed. Color-tunable emissions in GdVO4:Dy(3+),Eu(3+) phosphors are realized through adopting different excitation wavelengths or adjusting the appropriate concentration of Dy(3+) and Eu(3+) when excited by a single excitation wavelength. In addition, the as-prepared samples show paramagnetic properties at room temperature. This kind of multifunctional color-tunable phosphor has great potential applications in the fields of photoelectronic devices and biomedical sciences.

SQUID magnetometry and magneto-optics of epitaxial EuS

International Nuclear Information System (INIS)

Rumpf, K.; Granitzer, P.; Krenn, H.; Kellner, W.; Pascher, H.; Kirchschlager, R.; Janecek, S.

2004-01-01

The complicated (H,T)-magnetic phase diagram of EuS is caused by the critical balance between nearest and next nearest neighbour exchange interaction (J NN = 0.119 K and J NNN =-0.1209 K) and leads to various spin arrangements NNSS..., NSN..., NNS, NNN... [NS denotes opposite ferromagnetic order in adjacent (111) planes]. Beside the subtle local exchange of 5d-t 2g electrons and localized holes with neighbouring Eu-4f spins, obviously also the strain status influences the occurrence of these different phases. We investigate the magnetic ordering phenomenon in a strained 2.5 μm EuS film on BaF 2 substrate by SQUID magnetometry and magneto-optics like spectral Faraday- and Kerr-effect measurements for temperatures from 2 K up to 200 K and for magnetic field up to 5 T. The magneto-optical probe monitors the local environment of the photoexcited electron-hole pair, called magnetic exciton, located within a ferromagnetic surrounding (photoinduced magnetic polaron), whereas the integral magnetization measured by SQUID is most sensitive to long-range magnetic ordering. In spite of the dissimilarity of measurement techniques we find an influence of the long-range magnetic order (e.g. of the NNS- or NNN-matrix) on the non-resonant Kerr reflection. The complementarity of SQUID and magneto-optical methods is stringent only in the (resonant) spectral range, where magnetic polarons are formed. (author)

Effects of rock wool on the lungs evaluated by magnetometry and biopersistence test

Directory of Open Access Journals (Sweden)

Tomita Masayuki

2009-03-01

Full Text Available Abstract Background Asbestos has been reported to cause pulmonary fibrosis, and its use has been banned all over the world. The related industries are facing an urgent need to develop a safer fibrous substance. Rock wool (RW, a kind of asbestos substitute, is widely used in the construction industry. In order to evaluate the safety of RW, we performed a nose-only inhalation exposure study in rats. After one-month observation period, the potential of RW fibers to cause pulmonary toxicity was evaluated based on lung magnetometry findings, pulmonary biopersistence, and pneumopathology. Methods Using the nose-only inhalation exposure system, 6 male Fischer 344 rats (6 to 10 weeks old were exposed to RW fibers at a target fiber concentration of 100 fibers/cm3 (length [L] > 20 μm for 6 hours daily, for 5 consecutive days. As a magnetometric indicator, 3 mg of triiron tetraoxide suspended in 0.2 mL of physiological saline was intratracheally administered after RW exposure to these rats and 6 unexposed rats (controls. During one second magnetization in 50 mT external magnetic field, all magnetic particles were aligned, and immediately afterwards the strength of their remanent magnetic field in the rat lungs was measured in both groups. Magnetization and measurement of the decay (relaxation of this remanent magnetic field was performed over 40 minutes on 1, 3, 14, and 28 days after RW exposure, and reflected cytoskeleton dependent intracellular transport within macrophages in the lung. Similarly, 24 and 12 male Fisher 344-rats were used for biopersistence test and pathologic evaluation, respectively. Results In the lung magnetometric evaluation, biopersistence test and pathological evaluation, the arithmetic mean value of the total fiber concentration was 650.2, 344.7 and 390.7 fibers/cm3, respectively, and 156.6, 93.1 and 95.0 fibers/cm3 for fibers with L > 20 μm, respectively. The lung magnetometric evaluation revealed that impaired relaxation

Electron spin resonance as a high sensitivity technique for environmental magnetism: determination of contamination in carbonate sediments

Science.gov (United States)

Crook, Nigel P.; Hoon, Stephen R.; Taylor, Kevin G.; Perry, Chris T.

2002-05-01

This study investigates the application of high sensitivity electron spin resonance (ESR) to environmental magnetism in conjunction with the more conventional techniques of magnetic susceptibility, vibrating sample magnetometry (VSM) and chemical compositional analysis. Using these techniques we have studied carbonate sediment samples from Discovery Bay, Jamaica, which has been impacted to varying degrees by a bauxite loading facility. The carbonate sediment samples contain magnetic minerals ranging from moderate to low concentrations. The ESR spectra for all sites essentially contain three components. First, a six-line spectra centred around g = 2 resulting from Mn2+ ions within a carbonate matrix; second a g = 4.3 signal from isolated Fe3+ ions incorporated as impurities within minerals such as gibbsite, kaolinite or quartz; third a ferrimagnetic resonance with a maxima at 230 mT resulting from the ferrimagnetic minerals present within the bauxite contamination. Depending upon the location of the sites within the embayment these signals vary in their relative amplitude in a systematic manner related to the degree of bauxite input. Analysis of the ESR spectral components reveals linear relationships between the amplitude of the Mn2+ and ferrimagnetic signals and total Mn and Fe concentrations. To assist in determining the origin of the ESR signals coral and bauxite reference samples were employed. Coral representative of the matrix of the sediment was taken remote from the bauxite loading facility whilst pure bauxite was collected from nearby mining facilities. We find ESR to be a very sensitive technique particularly appropriate to magnetic analysis of ferri- and para-magnetic components within environmental samples otherwise dominated by diamagnetic (carbonate) minerals. When employing typical sample masses of 200 mg the practical detection limit of ESR to ferri- and para-magnetic minerals within a diamagnetic carbonate matrix is of the order of 1 ppm and 1 ppb

Optical and magnetic properties of Co-doped CuO flower/plates/particles-like nanostructures.

Science.gov (United States)

Basith, N Mohamed; Vijaya, J Judith; Kennedy, L John; Bououdina, M; Hussain, Shamima

2014-03-01

In this study, pure and Co-doped CuO nanostructures (0.5, 1.0, 1.5, and 2.0 at wt% of Co) were synthesized by microwave combustion method. The prepared samples were characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). Powder X-ray diffraction patterns refined by the Rietveld method indicated the formation of single-phase monoclinic structure. The surface morphology and elemental analysis of Co-doped CuO nanostructures were studied by using HR-SEM and EDX. Interestingly, the morphology was found to change considerably from nanoflowers to nanoplates then to nanoparticles with the variation of Co concentration. The optical band gap calculated using DRS was found to be 2.1 eV for pure CuO and increases up to 3.4 eV with increasing cobalt content. Photoluminescence measurements also confirm these results. The magnetic measurements indicated that the obtained nanostructures were ferromagnetic at room temperature with an optimum value of saturation magnetization at 1.0 wt.% of Co-doped CuO, i.e., 970 micro emu/g.

Nanoscale magnetometry through quantum control of nitrogen–vacancy centres in rotationally diffusing nanodiamonds

International Nuclear Information System (INIS)

Maclaurin, D; Hall, L T; Martin, A M; Hollenberg, L C L

2013-01-01

The confluence of quantum physics and biology is driving a new generation of quantum-based sensing and imaging technology capable of harnessing the power of quantum effects to provide tools to understand the fundamental processes of life. One of the most promising systems in this area is the nitrogen–vacancy centre in diamond—a natural spin qubit which remarkably has all the right attributes for nanoscale sensing in ambient biological conditions. Typically the nitrogen–vacancy qubits are fixed in tightly controlled/isolated experimental conditions. In this work quantum control principles of nitrogen–vacancy magnetometry are developed for a randomly diffusing diamond nanocrystal. We find that the accumulation of geometric phases, due to the rotation of the nanodiamond plays a crucial role in the application of a diffusing nanodiamond as a bio-label and magnetometer. Specifically, we show that a freely diffusing nanodiamond can offer real-time information about local magnetic fields and its own rotational behaviour, beyond continuous optically detected magnetic resonance monitoring, in parallel with operation as a fluorescent biomarker. (paper)

Hydrothermal synthesis of Ag@TiO2–Fe3O4 nanocomposites using sonochemically activated precursors: magnetic, photocatalytic and antibacterial properties

International Nuclear Information System (INIS)

Bokare, Anuja; Singh, Hema; Nair, Roopa; Sabharwal, Sushma; Athawale, Anjali A; Pai, Mrinal

2014-01-01

Fe 3 O 4 –TiO 2 nanocomposites have been synthesized by hydrothermal method using sonochemically activated precursors. X-ray diffraction analysis of the samples reveals the formation of pure phase composites. The optical properties of the composites are superior to TiO 2 as noted from the red shift in the diffused reflectance spectra of the composites. The presence of nanocubes of Fe 3 O 4 , nanospheres of TiO 2 and heterojunctions of the two in the composite samples have been observed in transmission electron micrographs. The magnetic properties of the samples were determined with the help of vibrating sample magnetometry (VSM) and magnetic force microscopy (MFM). The photocatalytic activity of the samples was investigated in terms of degradation of methyl orange (MO) dye. The composites could be easily separated from the reaction mixture after photocatalysis due to their magnetic behaviour. However, the photocatalytic activity of the composites was observed to be lower compared to bare TiO 2 . The composite (15% Fe 3 O 4 –TiO 2 ) when modified by coating it with Ag showed enhanced photocatalytic activity. Further, the antibacterial activities of the samples were also examined using E. coli as a model organism. Positive results were obtained only for the Ag coated composite with lower MIC (minimum inhibition concentration) values. (paper)

Hydrothermal synthesis of Ag@TiO2-Fe3O4 nanocomposites using sonochemically activated precursors: magnetic, photocatalytic and antibacterial properties

Science.gov (United States)

Bokare, Anuja; Singh, Hema; Pai, Mrinal; Nair, Roopa; Sabharwal, Sushma; Athawale, Anjali A.

2014-12-01

Fe3O4-TiO2 nanocomposites have been synthesized by hydrothermal method using sonochemically activated precursors. X-ray diffraction analysis of the samples reveals the formation of pure phase composites. The optical properties of the composites are superior to TiO2 as noted from the red shift in the diffused reflectance spectra of the composites. The presence of nanocubes of Fe3O4, nanospheres of TiO2 and heterojunctions of the two in the composite samples have been observed in transmission electron micrographs. The magnetic properties of the samples were determined with the help of vibrating sample magnetometry (VSM) and magnetic force microscopy (MFM). The photocatalytic activity of the samples was investigated in terms of degradation of methyl orange (MO) dye. The composites could be easily separated from the reaction mixture after photocatalysis due to their magnetic behaviour. However, the photocatalytic activity of the composites was observed to be lower compared to bare TiO2. The composite (15% Fe3O4-TiO2) when modified by coating it with Ag showed enhanced photocatalytic activity. Further, the antibacterial activities of the samples were also examined using E. coli as a model organism. Positive results were obtained only for the Ag coated composite with lower MIC (minimum inhibition concentration) values.

'NC100150', a preparation of iron oxide nanoparticles ideal for positive-contrast MR angiography.

Science.gov (United States)

Kellar, K E; Fujii, D K; Gunther, W H; Briley-Saebø, K; Spiller, M; Koenig, S H

1999-08-01

A laboratory-scale synthesis of NC100150 (iron oxide particles with an oxidized starch coating) was characterized by magnetization measurements (vibrating sample magnetometry, VSM), relaxometry (1/T1 NMRD profiles and 1/T2 at 10 and 20 MHz), and dynamic light scattering (photon correlation spectroscopy, PCS). The results were related to give a self-consistent physical description of the particles: a water-impenetrable part making up 12% of the total particle volume, 82% of this volume consisting of an iron oxide core and the remaining 18% consisting of an oxidized starch rind; and, a water-penetrable part making up 88% of the total particle volume, consisting of oxidized starch polymers and entrained water molecules. Relating the magnetization to the relaxometry results required that the oxidized starch coating slows the diffusivity of solvent water molecules in the vicinity of the iron oxide cores. The effect of the organic coating on water diffusivity, not previously considered in the application of relaxation theory to iron oxide nanoparticles, is supported by the much greater (factor of about 2) diameter obtained from the dynamic light scattering measurements in comparison to that obtained from the magnetization measurements. The present work shows that three physical techniques--VSM, relaxometry, and PCS--are needed for properly assessing iron oxide nanoparticles for use as contrast agents for magnetic resonance angiography (MRA). It is also shown that NC100150 has a narrow range of diameters and the smallest value of r2/r1 reported to date, an asset for MRA.

Synthesis and characterization of Acacia gum-Fe0Np-silica nanocomposite: an efficient Fenton-like catalyst for the degradation of Remazol Brilliant Violet dye

Science.gov (United States)

Singh, Vandana; Singh, Jadveer; Srivastava, Preeti

2018-04-01

Acacia gum-Fe0Np-silica nanocomposite (GFS1) has been crafted through sol-gel technique using a two-step process that involved the reduction of iron salt to zerovalent iron nanoparticles (Fe0Nps) followed by their impregnation within Acacia gum-silica matrix. GFS1 was characterized using Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometry (VSM), and X-ray photoelectron spectroscopy (XPS) techniques. GFS1 is decorated with Fe0Nps of 5 nm average size. The VSM study revealed that GFS1 has ferromagnetic nature. GFS1 was used as a heterogeneous Fenton-like catalyst for the degradation of azo dyes using Remazol Brilliant Violet (RBV) dye as a model dye. In first 5 min of operation, > 86% dye degradation was achieved and 94% dye (from 100 mg L-1 dye solution) was successfully degraded in 50 min. The dye degradation followed pseudo-first-order kinetics. The GFS1 performed efficiently well over the wide range of dye concentrations (25-200 mg L-1). The catalyst was reused for eight repeated cycles where 12.5% dye degradation was possible even in the eighth cycle. The catalyst behaved fairly well for the degradation of Metanil Yellow (MY) and Orange G (OG) dyes also. Under the optimum conditions of RBV dye degradation, Metanil Yellow (MY) and Orange G (OG) dyes were degraded to the extent of 97 and 26.3%, respectively.

Growth of magnetite films by a hydrogel method

Energy Technology Data Exchange (ETDEWEB)

Velásquez, A.A., E-mail: avelas26@eafit.edu.edu.co [Grupo de Electromagnetismo Aplicado, Universidad EAFIT, A.A. 3300, Medellín (Colombia); Marín, C.C. [Grupo de Electromagnetismo Aplicado, Universidad EAFIT, A.A. 3300, Medellín (Colombia); Urquijo, J.P. [Grupo de Estado Sólido, Instituto de Física, Universidad de Antioquia, A.A. 1226, Medellín (Colombia)

2017-06-15

Magnetite (Fe{sub 3}O{sub 4}) films were grown on glass substrates by formation and condensation of complex of iron oxides in an agarose hydrogel. The obtained films were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Room Temperature Mössbauer Spectroscopy (TMS), Vibrating Sample Magnetometry (VSM), Atomic Force Microscopy (AFM) and Voltage vs. Current measurements by the four-point method. FTIR and TGA measurements showed that some polymer chains of agarose remain linked to the surface of the magnetic particles of the films after heat treatment. SEM measurements showed that the films are composed by quasi spherical particles with sizes around 55 nm. Mössbauer spectroscopy measurements showed two sextets with broaden lines, which were assigned to magnetite with a distributed particle size, and two doublets, which were assigned to superparamagnetic phases of magnetite. For the specific dimensions of the films prepared, measurements of Voltage vs. Current showed an ohmic behavior for currents between 0 and 200 nA, with a resistance of 355 kΩ.

Magnetite/CdTe magnetic-fluorescent composite nanosystem for magnetic separation and bio-imaging

International Nuclear Information System (INIS)

Kale, Anup; Yadav, Prasad; Gholap, Haribhau; Jog, J P; Ogale, Satishchandra; Kale, Sonia; Shastry, Padma; Pasricha, Renu; Lefez, Benoit; Hannoyer, Beatrice

2011-01-01

A new synthesis protocol is described to obtain a CdTe decorated magnetite bifunctional nanosystem via dodecylamine (DDA) as cross linker. High resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDAX), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and fluorescence microscopy are used to characterize the constitution, size, composition and physical properties of these superparamagnetic-fluorescent nanoparticles. These CdTe decorated magnetite nanoparticles were then functionalized with anti-epidermal growth factor receptor (EGFR) antibody to specifically target cells expressing this receptor. The EGFR is a transmembrane glycoprotein and is expressed on tumor cells from different tissue origins including human leukemic cell line Molt-4 cells. The magnetite-CdTe composite nanosystem is shown to perform excellently for specific selection, magnetic separation and fluorescent detection of EGFR positive Molt-4 cells from a mixed population. Flow cytometry and confocal laser scanning microscopy results show that this composite nanosystem has great potential in antibody functionalized magnetic separation and imaging of cells using cell surface receptor antibody.

Photodegradation of Methylene Blue by TiO2-Fe3O4-Bentonite Magnetic Nanocomposite

Directory of Open Access Journals (Sweden)

Wei Chen

2015-01-01

Full Text Available Fe3O4-bentonite nanoparticles have been prepared by a coprecipitation technique under a nitrogen atmosphere. An aqueous suspension of bentonite was first modified with FeCl2 and FeCl3. TiO2 was then loaded onto the surface of the Fe3O4-bentonite by a sol-gel method. After sufficient drying, the colloidal solution was placed in a muffle furnace at 773 K to obtain the TiO2-Fe3O4-bentonite composite. The material has been characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD analysis, and vibrating sample magnetometry (VSM. Morphological observation showed that Fe3O4 and TiO2 nanoparticles had been adsorbed on the surface of bentonite nanoneedles. The material was then applied for the photodegradation of the azo dye methylene blue (MB. It was found that the removal efficiency of MB exceeded 90% under UV illumination, and that only a 20% mass loss was incurred after six cycles. The composite material thus showed good photocatalytic performance and recycling properties.

Growth of magnetite films by a hydrogel method

International Nuclear Information System (INIS)

Velásquez, A.A.; Marín, C.C.; Urquijo, J.P.

2017-01-01

Magnetite (Fe 3 O 4 ) films were grown on glass substrates by formation and condensation of complex of iron oxides in an agarose hydrogel. The obtained films were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Room Temperature Mössbauer Spectroscopy (TMS), Vibrating Sample Magnetometry (VSM), Atomic Force Microscopy (AFM) and Voltage vs. Current measurements by the four-point method. FTIR and TGA measurements showed that some polymer chains of agarose remain linked to the surface of the magnetic particles of the films after heat treatment. SEM measurements showed that the films are composed by quasi spherical particles with sizes around 55 nm. Mössbauer spectroscopy measurements showed two sextets with broaden lines, which were assigned to magnetite with a distributed particle size, and two doublets, which were assigned to superparamagnetic phases of magnetite. For the specific dimensions of the films prepared, measurements of Voltage vs. Current showed an ohmic behavior for currents between 0 and 200 nA, with a resistance of 355 kΩ.

Magnetic field-induced cluster formation and variation of magneto-optical signals in zinc-substituted ferrofluids

Energy Technology Data Exchange (ETDEWEB)

Nair, S.S. [Department of Physics, Cochin University of Science and Technology, Cochin 682 022 (India)]. E-mail: swapna@cusat.ac.in; Rajesh, S. [Department of Physics, Cochin University of Science and Technology, Cochin 682 022 (India); Abraham, V.S. [School of Engineering and Sciences, International University of Bremen, 28759 (Germany); Anantharaman, M.R. [Department of Physics, Cochin University of Science and Technology, Cochin 682 022 (India)]. E-mail: mraiyer@yahoo.com; Nampoori, V.P.N. [International School of Photonics, Cochin University of Science and Technology, Cochin-22 (India)

2006-10-15

Fine magnetic particles (size{approx_equal}100 A) belonging to the series Zn {sub x} Fe{sub 1-} {sub x} Fe{sub 2}O{sub 4} were synthesized by cold co-precipitation methods and their structural properties were evaluated using X-ray diffraction. Magnetization studies have been carried out using vibrating sample magnetometry (VSM) showing near-zero loss loop characteristics. Ferrofluids were then prepared employing these fine magnetic powders using oleic acid as surfactant and kerosene as carrier liquid by modifying the usually reported synthesis technique in order to induce anisotropy and enhance the magneto-optical signals. Liquid thin films of these fluids were prepared and field-induced laser transmission through these films was studied. The transmitted light intensity decreases at the centre with applied magnetic field in a linear fashion when subjected to low magnetic fields and saturate at higher fields. This is in accordance with the saturation in cluster formation. The pattern exhibited by these films in the presence of different magnetic fields was observed with the help of a CCD camera and was recorded photographically.

Effect of Ca substitution on some physical properties of nano-structured and bulk Ni-ferrite samples

Science.gov (United States)

Assar, S. T.; Abosheiasha, H. F.

2015-01-01

Nanoparticles of Ni1-xCaxFe2O4 (x=0.0, 0.02, 0.04, 0.06 and 0.10) were prepared by citrate precursor method. A part of these samples was sintered at 600 °C for 2 h in order to keep the particles within the nano-size while the other part was sintered at 1000 °C to let the particles to grow to the bulk size. The effect of Ca2+ ion substitution in nickel ferrite on some structural, magnetic, electrical and thermal properties was investigated. All samples were characterized by using X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). A two probe method was used to measure the dc electrical conductivity whereas the photoacoustic (PA) technique was used to determine the thermal diffusivity of the samples. To interpret different experimental results for nano and bulk samples some cation distributions were assumed based on the VSM and XRD data. These suggested cation distributions give logical explanations for other experimental results such as the observed values of the absorption bands in FTIR spectra and the dc conductivity results. Finally, in the thermal measurements it was found that increasing the Ca2+ ion content causes a decrease in the thermal diffusivity of both nano and bulk samples. The explanation of this behavior is ascribed to the phonon-phonon scattering.

Fiber-Optic Magnetometry and Thermometry Using Optically Detected Magnetic Resonance With Nitrogen-Vacancy Centers in Diamond

Science.gov (United States)

Blakley, Sean Michael

Nitrogen--vacancy diamond (NVD) quantum sensors are an emerging technology that has shown great promise in areas like high-resolution thermometry and magnetometry. Optical fibers provide attractive new application paradigms for NVD technology. A detailed description of the fabrication processes associated with the development of novel fiber-optic NVD probes are presented in this work. The demonstrated probes are tested on paradigmatic model systems designed to ascertain their suitability for use in challenging biological environments. Methods employing optically detected magnetic resonance (ODMR) are used to accurately measure and map temperature distributions of small objects and to demonstrate emergent temperature-dependent phenomena in genetically modified living organisms. These methods are also used to create detailed high resolution spatial maps of both magnetic scalar and magnetic vector field distributions of spatially localized weak field features in the presence of a noisy, high-field background.

Capitalistic Firms as Cognitive Intelligent and Explorative Agents. The Beer’s VSM and Mella’s Most Views

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Piero MELLA

2015-12-01

Full Text Available In this paper we propose a general model to understand (not merely describe the operating logic of Business Value-Creating Organizations and, in particular of the capitalistic firm - that is, the business for-profit organization. When viewed as autopoietic and teleological organizations, firms can be interpreted both as viable systems (following Beer’s Viable System Model, or VSM and as operating systems for efficient transformation (following Mella’s MOEST, or Model of the Organization as an Efficient System of Transformation. Beer believes that organizations must be viewed as viable systems, which, through their structure, which is capable of learning and cognition, can achieve an enduring structural coupling with the environment, continuing in this way to exist for a long time through continually adapting to the environment. Mella asserts that organizations must be conceived of as transformation systems that carry out five parallel transformations: (1 a productive transformation of factors into production; this is a transformation of utility, governed by productivity and by quality; (2 an economic transformation of costs and revenues into operating income; this is a transformation of value, governed by prices and therefore by the market; (3 a financial transformation of risks, which transforms capital into returns and guarantees the maintenance of its financial integrity; (4 an entrepreneurial transformation of information into strategies, which leads to a continual readjustment of the firm's strategic position; (5 a managerial (organizational transformation of strategies into actions of management control. The MOEST proposes a system of performance indices and measures and highlights the mutual relationships among these indexes. Based on VSM and MOEST, we will try to demonstrate that, just as individuals in a Social System are responsible for their own actions and behavior with respect to the other individuals in the system

Ferrimagnetic properties of Co/(Gd-Co) multilayers

International Nuclear Information System (INIS)

Svalov, A.V.; Fernandez, A.; Vas'kovskiy, V.O.; Tejedor, M.; Barandiaran, J.M.; Orue, I.; Kurlyandskaya, G.V.

2006-01-01

Co/(Gd-Co) multilayers have been prepared by rf-sputtering and investigated by means of Transverse Magnetooptic Kerr Effect (TMOKE), SQUID and VSM magnetometry. The composition of amorphous Gd 0.36 Co 0.64 layers was chosen so that their saturation magnetization was dominated by Gd moments in all the temperature range. Co and Gd-Co layers formed a macroscopic ferrimagnetically coupled system displaying a compensation temperature. Complete magnetic moment compensation was found at such point. An inversion of TMOKE hysteresis loops and a divergent behaviour of coercivity were also observed. By changing the layers thickness it has been possible to control the magnetic characteristics of the Co/(Gd-Co) structures, in particular the compensation takes place at different temperatures

Volumetric localization of epileptic activities in tuberous sclerosis using synthetic aperture magnetometry

Energy Technology Data Exchange (ETDEWEB)

Xiao, Zheng [Hospital for Sick Children, Research Institute, Toronto (Canada); Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Xiang, Jing [Hospital for Sick Children, Research Institute, Toronto (Canada); Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Holowka, Stephanie; Chuang, Sylvester [Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Hunjan, Amrita; Sharma, Rohit; Otsubo, Hiroshi [Hospital for Sick Children, Division of Neurology, Toronto (Canada)

2006-01-01

Magnetoencephalography (MEG) is a novel noninvasive technique for localizing epileptic zones. Tuberous sclerosis complex (TSC) is often associated with medically refractory epilepsy with multiple epileptic zones. Surgical treatment of TSC requires accurate localization of epileptogenic tubers. The objective of this study was to introduce a new MEG technique, synthetic aperture magnetometry (SAM), to volumetrically localize irritable zones and clarify the correlations between SAM, dipole modeling and anatomical tubers. Eight pediatric patients with TSC confirmed by clinical and neuroimaging findings were retrospectively studied. MEG data were recorded using a whole-cortex CTF OMEGA system. Sleep deprivation was employed to provoke epileptiform activity. Irritable zones were localized using both dipole modeling and SAM. MRI detected 42 tubers in the eight patients. Dipole modeling localized 28 irritable zones, and 19 out of the 28 zones were near tubers (19/42, 45%). SAM found 51 irritable zones, and 31 out of the 51 zones were near tubers (31/42, 74%). Among the 51 irritable zones determined by SAM, thirty-five zones were in 1-35 Hz, nine zones were in 35-60 Hz, and seven zones were in 60-120 Hz. The new method, SAM, yielded very plausible equivalent sources for patients who showed anatomical tubers on MRI. Compared to conventional dipole modeling, SAM appeared to offer increased detection of irritable zones and beneficial volumetric and frequency descriptions. (orig.)

A study of NiZnCu-ferrite/SiO2 nanocomposites with different ferrite contents synthesized by sol-gel method

International Nuclear Information System (INIS)

Yan Shifeng; Geng Jianxin; Chen Jianfeng; Yin Li; Zhou Yunchun; Liu Leijing; Zhou Enle

2005-01-01

Ni 0.65 Zn 0.35 Cu 0.1 Fe 1.9 O 4 /SiO 2 nanocomposites with different weight percentages of NiZnCu-ferrite dispersed in silica matrix were successfully fabricated by the sol-gel method using tetraethylorthosilicate (TEOS) as a precursor of silica, and metal nitrates as precursors of NiZnCu ferrite. The thermal decomposition process of the dried gel was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The obtained Ni 0.65 Zn 0.35 Cu 0.1 Fe 1.9 O 4 /SiO 2 nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), Mossbauer spectroscopy and vibrating sample magnetometry (VSM). The formation of stoichiometric NiZnCu-ferrite dispersed in silica matrix is confirmed when the weight percentage of ferrite is not more than 30%. Samples with higher ferrite content have small amount of α-Fe 2 O 3 . The transition from the paramagnetic to the ferromagnetic state is observed as the ferrite content increases from 20 to 90wt%. The magnetic properties of the nanocomposites are closely related to the ferrite content. The saturation magnetization increases with the ferrite content, while the coercivity reaches a maximum when the ferrite is 80wt% in the silica matrix

[Work organisation improvement methods applied to activities of Blood Transfusion Establishments (BTE): Lean Manufacturing, VSM, 5S].

Science.gov (United States)

Bertholey, F; Bourniquel, P; Rivery, E; Coudurier, N; Follea, G

2009-05-01

Continuous improvement of efficiency as well as new expectations from customers (quality and safety of blood products) and employees (working conditions) imply constant efforts in Blood Transfusion Establishments (BTE) to improve work organisations. The Lean method (from "Lean" meaning "thin") aims at identifying wastages in the process (overproduction, waiting, over-processing, inventory, transport, motion) and then reducing them in establishing a mapping of value chain (Value Stream Mapping). It consists in determining the added value of each step of the process from a customer perspective. Lean also consists in standardizing operations while implicating and responsabilizing all collaborators. The name 5S comes from the first letter of five operations of a Japanese management technique: to clear, rank, keep clean, standardize, make durable. The 5S method leads to develop the team working inducing an evolution of the way in the management is performed. The Lean VSM method has been applied to blood processing (component laboratory) in the Pays de la Loire BTE. The Lean 5S method has been applied to blood processing, quality control, purchasing, warehouse, human resources and quality assurance in the Rhône-Alpes BTE. The experience returns from both BTE shows that these methods allowed improving: (1) the processes and working conditions from a quality perspective, (2) the staff satisfaction, (3) the efficiency. These experiences, implemented in two BTE for different processes, confirm the applicability and usefulness of these methods to improve working organisations in BTE.

Copper, gold, and silver decorated magnetic core-polymeric shell nanostructures for destruction of pathogenic bacteria

Science.gov (United States)

Padervand, Mohsen; Karanji, Ahmad Kiani; Elahifard, Mohammad Reza

2017-05-01

Fe3O4 magnetic nanoparticles (MNPs) were prepared by co-precipitation method. The nanoparticles were silica coated using TEOS, and then modified by the polymeric layers of polypropylene glycol (PPG) and polyethylene glycol (PEG). Finally, the core-shell samples were decorated with Ag, Au, and Cu nanoparticles. The products were characterized by vibrating sample magnetometry (VSM), TGA, SEM, XRD, and FTIR methods. The antibacterial activity of the prepared samples was evaluated in inactivation of E. coli and S. aureus microorganisms, representing the Gram-negative and Gram-positive species, respectively. The effect of solid dosage, bacteria concentration and type of polymeric modifier on the antibacterial activity was investigated. TEM images of the bacteria were recorded after the treatment time and according to the observed changes in the cell wall, the mechanism of antibacterial action was discussed. The prepared nanostructures showed high antibacterial activity against both Gram-negative and Gram-positive bacteria. This was due to the leaching of metal ions which subsequently led to the lysis of bacteria. A theoretical investigation was also done by studying the interaction of loaded metals with the nucleotide components of the microorganism DNA, and the obtained results were used to explain the experimental data. Finally, based on the observed inactivation curves, we explain the antibacterial behavior of the prepared nanostructures mathematically.

Facile Fabrication of Highly Active Magnetic Aminoclay Supported Palladium Nanoparticles for the Room Temperature Catalytic Reduction of Nitrophenol and Nitroanilines

Directory of Open Access Journals (Sweden)

Lei Jia

2018-06-01

Full Text Available Magnetically recyclable nanocatalysts with excellent performance are urgent need in heterogeneous catalysis, due to their magnetic nature, which allows for convenient and efficient separation with the help of an external magnetic field. In this research, we developed a simple and rapid method to fabricate a magnetic aminoclay (AC based an AC@Fe3O4@Pd nanocatalyst by depositing palladium nanoparticles (Pd NPs on the surface of the magnetic aminoclay nanocomposite. The microstructure and the magnetic properties of as-prepared AC@Fe3O4@Pd were tested using transmission electron microscopy (TEM, energy-dispersive X-ray spectroscopy (EDS, X-ray diffraction (XRD, and vibrating sample magnetometry (VSM analyses. The resultant AC@Fe3O4@Pd nanocatalyst with the magnetic Fe-based inner shell, catalytically activate the outer noble metal shell, which when combined with ultrafine Pd NPs, synergistically enhanced the catalytic activity and recyclability in organocatalysis. As the aminoclay displayed good water dispersibility, the nanocatalyst indicated satisfactory catalytic performance in the reaction of reducing nitrophenol and nitroanilines to the corresponding aminobenzene derivatives. Meanwhile, the AC@Fe3O4@Pd nanocatalyst exhibited excellent reusability, while still maintaining good activity after several catalytic cycles.

Magnetic properties of NiFe{sub 2}O{sub 4}/carbon nanofibers from Venezuelan petcoke

Energy Technology Data Exchange (ETDEWEB)

Briceño, Sarah, E-mail: sbriceno@ivic.gob.ve [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Silva, Pedro; Molina, Wilmer; Brämer-Escamilla, Werner; Alcalá, Olgi [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Cañizales, Edgard [Área de Análisis Químico Inorgánico, PDVSA, INTEVEP, Los Teques 1070-A (Venezuela, Bolivarian Republic of)

2015-05-01

NiFe{sub 2}O{sub 4}/carbon nanofibers (NiFe{sub 2}O{sub 4}/CNFs) have been successfully synthesized by hydrotermal method using Venezuelan petroleum coke (petcoke) as carbon source and NiFe{sub 2}O{sub 4} as catalyst. The morphology, structural and magnetic properties of nanocomposite products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM) and electron paramagnetic resonance (EPR). XRD analysis revealed a cubic spinel structure and ferrite phase with high crystallinity. HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. At room temperature, NiFe{sub 2}O{sub 4}/CNFs show superparamagnetic behavior with a maximum magnetization of 15.35 emu/g. Our findings indicate that Venezuelan petroleum coke is suitable industrial carbon source for the growth of magnetic CNFs. - Highlights: • NiFe{sub 2}O{sub 4}/CNFs have been synthesized by hydrothermal method using petroleum coke. • Nickel ferrite nanoparticles were used as the catalyst. • HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. • The size of the nanoparticles defines the diameter of the CNFs.

Thickness Dependence of Magnetic Relaxation and E-J Characteristics in Superconducting (Gd-Y)-Ba-Cu-O Films with Strong Vortex Pinning

Energy Technology Data Exchange (ETDEWEB)

Polat, Ozgur [ORNL; Sinclair IV, John W [ORNL; Zuev, Yuri L [ORNL; Thompson, James R [ORNL; Christen, David K [ORNL; Cook, Sylvester W [ORNL; Kumar, Dhananjay [ORNL; Chen, Y [SuperPower Incorporated, Schenectady, New York; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York

2011-01-01

The dependence of the critical current density Jc on temperature, magnetic field, and film thickness has been investigated in (Gd-Y)BaCu-oxide materials of 0.7, 1.4, and 2.8 m thickness. Generally, the Jc decreases with film thickness at investigated temperatures and magnetic fields. The nature and strength of the pinning centers for vortices have been identified through angular and temperature measurements, respectively. These films do not exhibit c-axis correlated vortex pinning, but do have correlated defects oriented near the ab-planes. For all film thicknesses studied, strong pinning dominates at most temperatures. The vortex dynamics were investigated through magnetic relaxation studies in the temperature range of 5 77 K in 1 T and 3 T applied magnetic fields, H || surface-normal. The creep rate S is thickness dependent at high temperatures, implying that the pinning energy is also thickness dependent. Maley analyses of the relaxation data show an inverse power law variation for the effective pinning energy Ueff ~ (J0/J) . Finally, the electric field-current density (E-J) characteristics were determined over a wide range of dissipation by combining experimental results from transport, swept field magnetometry (VSM), and Superconducting Quantum Interference Device (SQUID) magnetometry. We develop a self-consistent model of the combined experimental results, leading to an estimation of the critical current density Jc0(T) in the absence of flux creep.

Examination of the magnetic hyperthermia and other magnetic properties of CoFe2O4@MgFe2O4 nanoparticles using external field Mössbauer spectroscopy

Science.gov (United States)

Park, Jeongho; Choi, Hyunkyung; Kim, Sam Jin; Kim, Chul Sung

2018-05-01

CoFe2O4@MgFe2O4 core/shell nanoparticles were synthesized by high temperature thermal decomposition with seed-mediated growth. The crystal structure and magnetic properties of the nanoparticles were investigated using X-ray diffractometry (XRD), vibrating sample magnetometry (VSM), and Mössbauer spectrometry. The magnetic hyperthermia properties were investigated using a MagneTherm device. Analysis of the XRD patterns showed that CoFe2O4@MgFe2O4 had a cubic spinel crystal structure with space group Fd-3m and a lattice constant (a0) of 8.3686 Å. The size and morphology of the CoFe2O4@MgFe2O4 nanoparticles were confirmed by HR-TEM. The VSM measurements showed that the saturation magnetization (MS) of CoFe2O4@MgFe2O4 was 77.9 emu/g. The self-heating temperature of CoFe2O4@MgFe2O4 was 37.8 °C at 112 kHz and 250 Oe. The CoFe2O4@MgFe2O4 core/shell nanoparticles showed the largest saturation magnetization value, while their magnetic hyperthermia properties were between those of the CoFe2O4 and MgFe2O4 nanoparticles. In order to investigate the hyperfine interactions of CoFe2O4, MgFe2O4, and CoFe2O4@MgFe2O4, we performed Mössbauer spectrometry at various temperatures. In addition, Mössbauer spectrometry of CoFe2O4@MgFe2O4 was performed at 4.2 K with applied fields of 0-4.5 T, and the results were analyzed with sextets for the tetrahedral A-site and sextets for the octahedral B-site.

Dipodal Silane-modified Nano Fe3O4/Polyurethane Magnetic Nanocomposites: Preparation and Characterization

Directory of Open Access Journals (Sweden)

Mir Mohammad Alavi Nikje

2016-01-01

Full Text Available Magnetic nanocomposites were prepared by incorporation of pure Fe3O4 and surface-modified Fe3O4 nanoparticles (dipodal silane-modified Fe3O4 into a polyurethane elastomer matrix by in situ polymerization method. In preparation of these magnetic nanocomposites, polycaprolactone (PCL was used as a polyester polyol. Because of dipole-dipole interactions between nanoparticles and a large surface area to volume ratio, the magnetic iron oxide nanoparticles tended to agglomerate. Furthermore, the most important challenge was to coat the surface of magnetic Fe3O4 nanoparticles in order to prepare well dispersed and stabilized Fe3O4 magnetic nanoparticles. It was observed that surface modification of Fe3O4 nanoparticles enhanced the dispersion of the nanoparticles in polyurethane matrices and allowed magnetic nanocomposites to be prepared with better properties. Surface modification of Fe3O4 was performed by dipodal silane synthesized based on 3-aminopropyltriethoxysilane (APTS and γ-glycidoxypropyl trimethoxysilane (GPTS. Dipodal silane-coated magnetic nanoparticles (DScMNPs were synthesized and incorporated into the polyurethane elastomer matrix as reinforcing agents. The formation of dipodal silane was investigated by Fourier transform infrared spectroscopy (FTIR, proton nuclear magnetic resonance spectroscopy (1H NMR and transmission electron microscopy (TEM. Characterization and study on the magnetic polyurethane elastomer nanocomposites were performed by FTIR, thermogravimetric analysis (TGA, scanning electron microscopy (SEM, vibrating sample magnetometry (VSM and dynamic mechanical thermal analysis (DMTA. The VSM results showed that the synthesized polyurethane elastomer nanocomposites had a superparamagnetic behavior. The TGA results showed that the thermal stability of dipodal silane-modified Fe3O4/PU nanocomposite was higher than that of Fe3O4/PU nanocomposite. This could be attributed to better dispersion and compatibility of dipodal silane

YIG based broad band microwave absorber: A perspective on synthesis methods

Science.gov (United States)

Sharma, Vinay; Saha, J.; Patnaik, S.; Kuanr, Bijoy K.

2017-10-01

The fabrication of a thin layer of microwave absorber that operates over a wide band of frequencies is still a challenging task. With recent advances in nanostructure synthesis techniques, considerable progress has been achieved in realizations of thin nanocomposite layer designed for full absorption of incident electromagnetic (EM) radiation covering S to K band frequencies. The primary objective of this investigation is to achieve best possible EM absorption with a wide bandwidth and attenuation >10 dB for a thin absorbing layer (few hundred of microns). Magnetic yttrium iron garnet (Y3Fe5O12; in short YIG) nanoparticles (NPs) were prepared by sol-gel (SG) as well as solid-state (SS) reaction methods to elucidate the effects of nanoscale finite size on the magnetic behavior of the particles and hence their microwave absorption capabilities. It is found that YIG prepared by these two methods are different in many ways. Magnetic properties investigated using vibrating sample magnetometry (VSM) exhibit that the coercivity (Hc) of solid-state NPs is much larger (72 Oe) than the sol-gel NPs (31 Oe). Microwave absorption properties were studied by ferromagnetic resonance (FMR) technique in field sweep mode at different fixed frequencies. A thin layer (∼300 μm) of YIG film was deposited using electrophoretic deposition (EPD) technique over a coplanar waveguide (CPW) transmission line made on copper coated RT/duroid® 5880 substrates. Temperature dependent magnetic properties were also investigated using VSM and FMR techniques. Microwave absorption properties were investigated at high temperatures (up to 300 °C) both for sol-gel and solid-state synthesized NPs and are related to skin depth of YIG films. It is observed that microwave absorption almost vanishes when the temperature reached the Néel temperature of YIG.

Evaluation of Antioxidant and Cytotoxicity Activities of Copper Ferrite (CuFe2O4 and Zinc Ferrite (ZnFe2O4 Nanoparticles Synthesized by Sol-Gel Self-Combustion Method

Directory of Open Access Journals (Sweden)

Samikannu Kanagesan

2016-08-01

Full Text Available Spinel copper ferrite (CuFe2O4 and zinc ferrite (ZnFe2O4 nanoparticles were synthesized using a sol-gel self-combustion technique. The structural, functional, morphological and magnetic properties of the samples were investigated by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, Transmission electron microscopy (TEM and vibrating sample magnetometry (VSM. XRD patterns conform to the copper ferrite and zinc ferrite formation, and the average particle sizes were calculated by using a transmission electron microscope, the measured particle sizes being 56 nm for CuFe2O4 and 68 nm for ZnFe2O4. Both spinel ferrite nanoparticles exhibit ferromagnetic behavior with saturation magnetization of 31 emug−1 for copper ferrite (50.63 Am2/Kg and 28.8 Am2/Kg for zinc ferrite. Both synthesized ferrite nanoparticles were equally effective in scavenging 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH free radicals. ZnFe2O4 and CuFe2O4 nanoparticles showed 30.57% ± 1.0% and 28.69% ± 1.14% scavenging activity at 125 µg/mL concentrations. In vitro cytotoxicity study revealed higher concentrations (>125 µg/mL of ZnFe2O4 and CuFe2O4 with increased toxicity against MCF-7 cells, but were found to be non-toxic at lower concentrations suggesting their biocompatibility.

Synthesis of magnetite nanoparticles-β-cyclodextrin complex

International Nuclear Information System (INIS)

Cobos Cruz, L.A.; Martinez Perez, C.A.; Monreal Romero, H.A.; Garcia Casillas, P.E.

2008-01-01

In this work, the synthesis and characterization of a magnetite (M) and β-cyclodextrin (CD) complex is presented. The chemical bonding between the magnetite and CD was studied as evidence of host-guest interaction; therefore the CD works like a reactor with the magnetite inside of it, as consequence the growth of the particle is restricted by the electrostatic interaction of M-CD complex. The particle size of the magnetite-cyclodextrin complex (M-CD) decreased 79.1% with 0.5% of CD. The average particle size of the M-CD complex was 10 nm. The saturation magnetization (σ s ) and intrinsic coercivity (H c ) increased 10% and 20%, respectively. In order to understand how the the CD affects the results obtained, the second derivate of remission function was obtained from the ultraviolet-visible spectra (UV-vis). Fourier transform infrared spectroscopy (FTIR) was used to elucidate the interaction between the magnetite and CD. The thermal analysis was measured by thermogravimetric and differential thermal analysis (TGA-DTA). The magnetic properties, intrinsic coercivity (H c ) and the saturation magnetization were determined by vibrating sample magnetometry (VSM); the size and shape of nanoparticles were determined by scanning electron microscopy (SEM). The identification of phases was made by X-ray diffraction

One-pot hydrothermal synthesis and characterization of CoFe{sub 2}O{sub 4} nanoparticles and its application as magnetically recoverable catalyst in oxidation of alcohols by periodic acid

Energy Technology Data Exchange (ETDEWEB)

Paul, Bappi; Purkayastha, Debraj Dhar; Dhar, Siddhartha Sankar, E-mail: ssd_iitg@hotmail.com

2016-09-15

A novel and facile approach for one-pot synthesis of spinel cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles (NPs) is presented here. The synthesis involves homogeneous chemical precipitation followed by hydrothermal heating, using tributylamine (TBA) as a hydroxylating agent. Polyethylene glycol (PEG) 4000 was used as surfactant. As-synthesized CoFe{sub 2}O{sub 4} NPs were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} adsorption-desorption isotherm (BET) and vibrating sample magnetometry (VSM). TEM image showed formation of spherical particles of sizes 2–30 nm. These NPs were used as magnetically recoverable catalyst in oxidation of alcohols to their corresponding aldehydes by periodic acid. This oxidative procedure is found to be highly efficient affording products in very high yield and selectivity. The easy magnetic separation of the catalyst and efficient reusability are key features of this methodology. - Highlights: • Hydrothermal synthesis of CoFe{sub 2}O{sub 4} NPs with (C{sub 4}H{sub 9}){sub 3}N as hydroxylating agent. • The TEM images showed the particles to be spherical in shape with sizes 2–30 nm. • CoFe{sub 2}O{sub 4} was used as recyclable catalyst for oxidation of alcohols by periodic acid.

AuPd Bimetallic Nanocrystals Embedded in Magnetic Halloysite Nanotubes: Facile Synthesis and Catalytic Reduction of Nitroaromatic Compounds

Directory of Open Access Journals (Sweden)

Lei Jia

2017-10-01

Full Text Available In this research, a facile and effective approach was developed for the preparation of well-designed AuPd alloyed catalysts supported on magnetic halloysite nanotubes (HNTs@Fe3O4@AuPd. The microstructure and the magnetic properties of HNTs@Fe3O4@AuPd were confirmed by transmission electron microscopy (TEM, high resolution TEM (HRTEM, energy-dispersive X-ray spectroscopy (EDS, and vibrating sample magnetometry (VSM analyses. The catalysts, fabricated by a cheap, environmentally friendly, and simple surfactant-free formation process, exhibited high activities during the reduction of 4-nitrophenol and various other nitroaromatic compounds. Moreover, the catalytic activities of the HNTs@Fe3O4@AuPd nanocatalysts were tunable via adjusting the atomic ratio of AuPd during the synthesis. As compared with the monometallic nanocatalysts (HNTs@Fe3O4@Au and HNTs@Fe3O4@Pd, the bimetallic alloyed HNTs@Fe3O4@AuPd nanocatalysts exhibited excellent catalytic activities toward the reduction of 4-nitrophenol (4-NP to 4-aminophenol. Furthermore, the as-obtained HNTs@Fe3O4@AuPd can be recycled several times, while retaining its functionality due to the stability and magnetic separation property.

Preparation and Characterization of Promoted Fe-V/SiO2 Nanocatalysts for Oxidation of Alcohols

Directory of Open Access Journals (Sweden)

Hamid Reza Rafiee

2013-01-01

Full Text Available A series of SiO2 supported iron-vanadium catalysts were prepared using sol-gel and wetness impregnation methods. This research investigates the effects of V and Cu on the structure and morphology of Fe/SiO2 catalysts. The SiO2 supported catalyst with the highest specific surface area and pore volume was obtained when it is containing 40 wt.% Fe, 15 wt.% V, and 2 wt.% Cu. Characterization of prepared catalysts was carried out by powder X-ray diffraction (XRD, scanning electron microcopy (SEM, vibrating sample magnetometry (VSM, Fourier transform infrared (FT-IR spectrometry, temperature program reduction (TPR, N2 physisorption, and thermal analysis methods such as thermal gravimetric analysis (TGA and differential scanning calorimetry (DSC. The Fe-V/SiO2 catalyst promoted with 2 wt.% of Cu exhibited typical ferromagnetic behavior at room temperature with a saturation magnetization value of 11.44 emu/g. This character of catalyst indicated great potential for application in magnetic separation technologies. The prepared catalyst was found to act as an efficient recoverable nanocatalyst for oxidation reaction of alcohols to aldehydes and ketones in aqueous media under mild condition. Moreover, the catalyst was reused five times without significant degradation in catalytic activity and performance.

Fast sono assisted ferrofluid mediated silver super - Adsorption over magnesium ferrite-copper sulfide chalcogenide with the aid of multivariate optimization.

Science.gov (United States)

Rezaei, Ali Asghar; Hossein Beyki, Mostafa; Shemirani, Farzaneh

2017-07-01

This research focuses on the development of a fast ultrasonic assisted ferrofluid mediated methodology to obtain the optimum conditions for silver adsorption from aqueous solutions. For this purpose magnesium ferrite-copper sulfide chalcogenide was synthesized and employed as an efficient nanosorbent. The sorbent was characterized with energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD) and vibrational sample magnetometry (VSM) techniques. For obtaining the optimal operating conditions of silver adsorption, response surface methodology (RSM) was used. Tests were performed by Box-Behnken design (BBD). The value of optimum conditions for silver adsorption include pH=2.5, adsorbent dosage=10.0mg, sonicating time=1min and ionic strength=2.2%. According optimum conditions, percentage of removal should be 99.34%. With replication of similar experiment (n=6) average percentage of 100±0.95% was obtained for Ag + adsorption which shows good agreement between predicted and experimental results. Silver ion adsorption follow Langmuir model with maximum sorption capacity of 2113mgg -1 . Ultrasonic power helped to prepare ferrofluid and demonstrated that had an important role in better dispersing of it in solution and efficient adsorption of analyte. Copyright © 2017 Elsevier B.V. All rights reserved.

The role of matching thickness on the wideband electromagnetic wave suppresser using single layer doped barium ferrite

International Nuclear Information System (INIS)

Shams Alam, Reza; Kavosh Tehrani, Masoud; Moradi, Mahmood; Hosseinpour, Ehsaneh; Sharbati, Ali

2011-01-01

The effect of Mg 2+ , Co 2+ and Ti 4+ substitution on microwave absorption has been studied for BaMg 0.5 Co 0.5 Ti 1.0 Fe 10 O 19 ferrite-acrylic resin composite in frequency range from 13 to 20 GHz. X-ray diffraction (XRD), scanning electron microscopy (SEM), vector network analysis and vibrating sample magnetometry (VSM) were employed to analyze structure, electromagnetic and microwave absorption properties of prepared ferrite. The obtained results of reflectivity demonstrate that by varying matching thickness along with weight percentage of ferrite to acrylic resin, the bandwidth coupled with reflection loss values of prepared composites can be easily tuned. Based on microwave measurement on reflectivity, it is found that BaMg 0.5 Co 0.5 Ti 1.0 Fe 10 O 19 is a good candidate for wideband electromagnetic compatibility and other practical applications at high frequency. - Research highlights: → In our previous paper, the microwave attenuation properties of doped ferrites were evaluated. → Here we deal with the new substitution in barium ferrite which can easily tune the bandwidth of the reflection loss properties. → To the best of knowledge, this is a so simple composition which can offer practical applications in the field.

One-pot hydrothermal synthesis and characterization of CoFe2O4 nanoparticles and its application as magnetically recoverable catalyst in oxidation of alcohols by periodic acid

International Nuclear Information System (INIS)

Paul, Bappi; Purkayastha, Debraj Dhar; Dhar, Siddhartha Sankar

2016-01-01

A novel and facile approach for one-pot synthesis of spinel cobalt ferrite (CoFe 2 O 4 ) nanoparticles (NPs) is presented here. The synthesis involves homogeneous chemical precipitation followed by hydrothermal heating, using tributylamine (TBA) as a hydroxylating agent. Polyethylene glycol (PEG) 4000 was used as surfactant. As-synthesized CoFe 2 O 4 NPs were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 adsorption-desorption isotherm (BET) and vibrating sample magnetometry (VSM). TEM image showed formation of spherical particles of sizes 2–30 nm. These NPs were used as magnetically recoverable catalyst in oxidation of alcohols to their corresponding aldehydes by periodic acid. This oxidative procedure is found to be highly efficient affording products in very high yield and selectivity. The easy magnetic separation of the catalyst and efficient reusability are key features of this methodology. - Highlights: • Hydrothermal synthesis of CoFe 2 O 4 NPs with (C 4 H 9 ) 3 N as hydroxylating agent. • The TEM images showed the particles to be spherical in shape with sizes 2–30 nm. • CoFe 2 O 4 was used as recyclable catalyst for oxidation of alcohols by periodic acid.

Crystal structure of superparamagnetic Mg0.2Ca0.8Fe2O4 nanoparticles synthesized by sol–gel method

International Nuclear Information System (INIS)

Escamilla-Pérez, A.M.; Cortés-Hernández, D.A.; Almanza-Robles, J.M.; Mantovani, D.; Chevallier, P.

2015-01-01

Powders of magnetic iron oxide nanoparticles (Mg 0.2 Ca 0.8 Fe 2 O 4 ) were prepared by a sol–gel method using ethylene glycol and nitrates of Fe, Ca and Mg as starting materials. Those powders were heat treated at different temperatures (573, 673, 773 and 873 K). In order to evaluate the effect of the heat treatment temperature on the nanoferrites properties, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques were used. It was found that the reaction products exhibit nanometric sizes and superparamagnetic behavior. It is also demonstrated that, as the heat treatment temperature increases, the particle size and the saturation magnetization of the nanoferrites are increased. - Highlights: • Mg 0.2 Ca 0.8 Fe 2 O 4 superparamagnetic nanoparticles were successfully synthesized. • Particle average sizes of Ca–Mg ferrites were within the range of 8–25 nm. • The nanoferrite treated at 873 K showed a stoichiometry close to Mg 0.2 Ca 0.8 Fe 2 O 4 . • The heat treatment temperature has a strong effect on the crystal structure. • These nanoparticles are potential materials for magnetic hyperthermia

Crystal structure of superparamagnetic Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4} nanoparticles synthesized by sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Escamilla-Pérez, A.M., E-mail: angel.mep@gmail.com [Cinvestav-Unidad Saltillo, Industria Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Cortés-Hernández, D.A., E-mail: dora.cortes@cinvestav.edu.mx [Cinvestav-Unidad Saltillo, Industria Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Almanza-Robles, J.M. [Cinvestav-Unidad Saltillo, Industria Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Mantovani, D.; Chevallier, P. [Laboratory for Biomaterials and Bioengineering, Department of Materials Engineering and University Hospital Research Center, Laval University, Quebec City, QC (Canada)

2015-01-15

Powders of magnetic iron oxide nanoparticles (Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4}) were prepared by a sol–gel method using ethylene glycol and nitrates of Fe, Ca and Mg as starting materials. Those powders were heat treated at different temperatures (573, 673, 773 and 873 K). In order to evaluate the effect of the heat treatment temperature on the nanoferrites properties, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques were used. It was found that the reaction products exhibit nanometric sizes and superparamagnetic behavior. It is also demonstrated that, as the heat treatment temperature increases, the particle size and the saturation magnetization of the nanoferrites are increased. - Highlights: • Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4} superparamagnetic nanoparticles were successfully synthesized. • Particle average sizes of Ca–Mg ferrites were within the range of 8–25 nm. • The nanoferrite treated at 873 K showed a stoichiometry close to Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4}. • The heat treatment temperature has a strong effect on the crystal structure. • These nanoparticles are potential materials for magnetic hyperthermia.

Synthesis and Characterization of Mixed Iron-Manganese Oxide Nanoparticles and Their Application for Efficient Nickel Ion Removal from Aqueous Samples

Science.gov (United States)

Serra, Antonio; Monteduro, Anna Grazia; Padmanabhan, Sanosh Kunjalukkal; Licciulli, Antonio; Bonfrate, Valentina; Salvatore, Luca; Calcagnile, Lucio

2017-01-01

Mixed iron-manganese oxide nanoparticles, synthesized by a simple procedure, were used to remove nickel ion from aqueous solutions. Nanostructures, prepared by using different weight percents of manganese, were characterized by transmission electron microscopy, selected area diffraction, X-ray diffraction, Raman spectroscopy, and vibrating sample magnetometry. Adsorption/desorption isotherm curves demonstrated that manganese inclusions enhance the specific surface area three times and the pores volume ten times. This feature was crucial to decontaminate both aqueous samples and food extracts from nickel ion. Efficient removal of Ni2+ was highlighted by the well-known dimethylglyoxime test and by ICP-MS analysis and the possibility of regenerating the nanostructure was obtained by a washing treatment in disodium ethylenediaminetetraacetate solution. PMID:28804670

Reflectance measurements of zooclasts and solid bitumen in Lower Paleozoic shales, southern Scandinavia

DEFF Research Database (Denmark)

Petersen, Henrik I.; Schovsbo, Niels H.; Nielsen, Arne Thorshøj

2013-01-01

-like particles and graptolite fragments. The Middle Cambrian to Furongian (upper Cambrian) shales may contain sparse fragments of vase-shaped microfossils (VSM) that seem to follow the maturation trend of chitinozoans. In the present sample set, the reflectance of chitinozoans and VSM is comparable...

Microwave absorption properties of lightweight absorber based on Fe{sub 50}Ni{sub 50}-coated poly(acrylonitrile) microspheres and reduced graphene oxide composites

Energy Technology Data Exchange (ETDEWEB)

Zhang, Bin [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Wang, Jun, E-mail: wgdfrp@whut.edu.cn [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Wang, Junpeng; Huo, Siqi [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Zhang, Bin [School of Science, Wuhan University of Technology, Wuhan 430070 (China); Tang, Yushan [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China)

2016-09-01

In this paper, we proposed a facile method to obtain the lightweight composites consisting of surface modified Fe{sub 50}Ni{sub 50}-coated poly(acrylonitrile) microspheres (PANS@SMF), reduced graphene oxide (RGO) and epoxy resin. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM) and vector network analyzer (VNA). Impedance matching condition and electromagnetic wave attenuation characteristic were used for the reflection loss (RL) performance of the composites. Compared with pure PANS@SMF and RGO composites, the −10 dB absorption bandwidth and the minimum RL of the hybrid composites were enhanced. The bandwidth less than −10 dB was almost 4.5 GHz in the range of 10 GHz to 14.5 GHz, with a matching thickness of 2.5 mm. The density of the hybrid composites was in the range of 0.25–0.34 g/cm{sup 3}. Therefore, the hybrid composite can be considered as a potential lightweight microwave absorber. - Highlights: • PANS@SMF – RGO epoxy composite was fabricated by a facile method. • The absorption bandwidth less than −10 dB can reach up to 4.5 GHz with layer thickness of 2.5 mm. • The density of the composites is in the range of 0.25–0.34 g/cm{sup 3} and can be considered as a lightweight microwave absorber.

High-field torque magnetometry for investigating magnetic anisotropy in Mn12-acetate nanomagnets

International Nuclear Information System (INIS)

Cornia, Andrea; Affronte, Marco; Gatteschi, Dante; Jansen, Aloysius G.M.; Caneschi, Andrea; Sessoli, Roberta

2001-01-01

The single-molecule superparamagnet [Mn 12 O 12 (OAc) 16 (H 2 O) 4 ]·2AcOH·4H 2 O (Mn 12 -acetate) has attracted considerable attention because it shows exceedingly slow paramagnetic relaxation at low temperature. The cluster has S 4 symmetry in the solid state and comprises four Mn(IV) ions (S=((3)/(2))) and eight Mn(III) ions (S=2) which are magnetically coupled to give an S=10 ground state. The ground manifold is largely split in zero magnetic field and many efforts have been spent to determine the zero-field splitting (zfs) parameters α, β and γ appearing in the fourth-order spin-Hamiltonian H=αS z 2 +βS z 4 +γ(S + 4 +S - 4 )+μ B B·g·S. These are of paramount importance for defining the magnetic anisotropy of the cluster, which in turn determines the slow relaxation of the magnetization and quantum tunneling effects at low temperatures. We want to show that cantilever torque magnetometry in high fields is a suitable technique for determining second- and fourth-order anisotropic contributions in high-spin molecules, such as Mn 12 -acetate. The main advantage of the method lies in its high sensitivity which allows to use very small single crystals. Torque curves have been recorded at 4.2 K by applying the magnetic field (0-28 T) very close to the ab-plane of the tetragonal unit cell. The zfs parameters obtained by this procedure [α=-0.389(5) cm -1 and β=-8.4(5)x10 -4 cm -1 ] are in excellent agreement with those determined by spectroscopic techniques, such as high-frequency EPR and inelastic neutron scattering

Thickness and angular dependent magnetic anisotropy of La0.67Sr0.33MnO3 thin films by Vectorial Magneto Optical Kerr Magnetometry

Science.gov (United States)

Chaluvadi, S. K.; Perna, P.; Ajejas, F.; Camarero, J.; Pautrat, A.; Flament, S.; Méchin, L.

2017-10-01

We investigate the in-plane magnetic anisotropy in La0.67Sr0.33MnO3 thin films grown on SrTiO3 (001) substrate using angular dependent room temperature Vectorial Magneto-Optical Kerr Magnetometry. The experimental data reveals that the magnetic anisotropy symmetry landscape significantly changes depending upon the strain and thickness. At low film thickness (12 and 25 nm) the dominant uniaxial anisotropy is due to interface effects, step edges due to mis-cut angle of SrTiO3 substrate. At intermediate thickness, the magnetic anisotropy presents a competition between magnetocrystalline (biaxial) and substrate step induced (uniaxial) anisotropy. Depending upon their relative strengths, a profound biaxial or uniaxial or mixed anisotropy is favoured. Above the critical thickness, magnetocrystalline anisotropy dominates all other effects and shows a biaxial anisotropy.

Designed Synthesis of Nanostructured Magnetic Hydroxyapatite Based Drug Nanocarrier for Anti-Cancer Drug Delivery toward the Treatment of Human Epidermoid Carcinoma

Directory of Open Access Journals (Sweden)

Bharath Govindan

2017-06-01

Full Text Available Superparamagnetic Fe3O4 nanoparticles on hydroxyapatite nanorod based nanostructures (Fe3O4/HAp were synthesized using hydrothermal techniques at 180 °C for 12 h and were used as drug delivery nanocarriers for cancer cell therapeutic applications. The synthesized Fe3O4/HAp nanocomposites were characterized by X-ray diffraction analysis (XRD, Field emission scanning electron microscopy (FESEM, Fourier transform infrared spectroscopy (FTIR, Brunauer-Emmett-Teller (BET-analysis, and vibrating sample magnetometry (VSM. The morphologies of the Fe3O4/HAp nanocomposites show 15 nm Fe3O4 nanoparticles dispersed in the form of rods. The BET result shows that the synthesized samples have a high specific surface area of 80 m2 g−1 with mesoporous structures. Magnetic measurements revealed that the sample has high saturation magnetization of 18 emu/g with low coercivity. The Fe3O4/HAp nanocomposites had a large specific surface area (SSA, high mesoporous volume, and good magnetic property, which made it a suitable nanocarrier for targeted drug delivery systems. The chemotherapeutic agent, andrographolide, was used to investigate the drug delivery behavior of the Fe3O4/HAp nanocomposites. The human epidermoid skin cancer cells (A431 were used as the model targeting cell lines by treating with andrographolide loaded Fe3O4/HAp nanosystems and were further evaluated for their antiproliferative activities and the induction of apoptosis. Also, the present nanocomposite shows better biocompatibility, therefore it can be used as suitable drug vehicle for cancer therapy applications.

The effect of yttrium substitution on the magnetic properties of magnetite nanoparticles

International Nuclear Information System (INIS)

Mozaffari, M.; Amighian, J.; Tavakoli, R.

2015-01-01

Superparamagnetic Y-substituted magnetite (Y x Fe 3–x O 4 ,with x=0.00, 0.10, 0.15, 0.20 and 0.40) nanoparticles were synthesized via hydrothermal reduction route in the presence of citric acid. The synthesized nanoparticles were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM) and gradient field thermomagnetic measurement. The results showed that a minimum amount of citric acid is required to obtain single phase Y-substituted magnetite nanoparticles. Citric acid acts as a modulator and reducing agent in the formation of spinel structure and controls nanoparticle size and crystallinity. Mean crystallite sizes of the single-phase powders were estimated by Williamson–Hall method. Curie temperature measurement of the samples shows that as yttrium content increases, the Curie temperature decreases. Magnetic measurements show that the saturation magnetization of the samples decreases as x increases up to 0.15 and then increases to x=0.20 and finally decreases again for x=0.40. - Highlights: • Single phase yttrium substituted magnetite nanoparticles were synthesized by hydrothermal-reduction route. • Citric acid plays a key role in reduction of Fe 3+ to Fe 2+ , which is necessary for the formation of magnetite phase. • It is possible to substitute yttrium ions for iron ones as high as x=0.4 by hydrothermal reduction route. • Pure magnetite nanoparticles prepared by this route has a high saturation magnetization. • Yttrium substituted magnetite nanoparticles are superparamagnet at room temperature

Advanced UXO Discrimination using Magnetometry: Understanding Remanent Magnetization

Science.gov (United States)

2009-09-01

moments of steel samples. The MRIP comprises six three-component fluxgate magnetometers symmetrically distributed around a rotating sample holder. Samples...comprises six three- component fluxgate magnetometers symmetrically distributed around a rotating sample holder. Samples are placed on the holder... fluxgate magnetometers symmetrically distributed around a rotating sample holder. Samples are placed on the holder and are slowly spun through two

Synthesis and Characterization of Mixed Iron-Manganese Oxide Nanoparticles and Their Application for Efficient Nickel Ion Removal from Aqueous Samples

Directory of Open Access Journals (Sweden)

Alessandro Buccolieri

2017-01-01

Full Text Available Mixed iron-manganese oxide nanoparticles, synthesized by a simple procedure, were used to remove nickel ion from aqueous solutions. Nanostructures, prepared by using different weight percents of manganese, were characterized by transmission electron microscopy, selected area diffraction, X-ray diffraction, Raman spectroscopy, and vibrating sample magnetometry. Adsorption/desorption isotherm curves demonstrated that manganese inclusions enhance the specific surface area three times and the pores volume ten times. This feature was crucial to decontaminate both aqueous samples and food extracts from nickel ion. Efficient removal of Ni2+ was highlighted by the well-known dimethylglyoxime test and by ICP-MS analysis and the possibility of regenerating the nanostructure was obtained by a washing treatment in disodium ethylenediaminetetraacetate solution.

Effects of Mg substitution on the structural and magnetic properties of Co0.5Ni0.5-x Mg x Fe2O4 nanoparticle ferrites

Science.gov (United States)

R, M. Rosnan; Z, Othaman; R, Hussin; Ali, A. Ati; Alireza, Samavati; Shadab, Dabagh; Samad, Zare

2016-04-01

In this study, nanocrystalline Co-Ni-Mg ferrite powders with composition Co0.5Ni0.5-x Mg x Fe2O4 are successfully synthesized by the co-precipitation method. A systematic investigation on the structural, morphological and magnetic properties of un-doped and Mg-doped Co-Ni ferrite nanoparticles is carried out. The prepared samples are characterized using x-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometry (VSM). The XRD analyses of the synthesized samples confirm the formation of single-phase cubic spinel structures with crystallite sizes in a range of ˜ 32 nm to ˜ 36 nm. The lattice constant increases with increasing Mg content. FESEM images show that the synthesized samples are homogeneous with a uniformly distributed grain. The results of IR spectroscopy analysis indicate the formation of functional groups of spinel ferrite in the co-precipitation process. By increasing Mg2+ substitution, room temperature magnetic measurement shows that maximum magnetization and coercivity increase from ˜ 57.35 emu/g to ˜ 61.49 emu/g and ˜ 603.26 Oe to ˜ 684.11 Oe (1 Oe = 79.5775 A·m-1), respectively. The higher values of magnetization M s and M r suggest that the optimum composition is Co0.5Ni0.4Mg0.1Fe2O4 that can be applied to high-density recording media and microwave devices. Project supported by the Ibnu Sina Institute for Scientific and Industrial Research, Physics Department of Universiti Teknologi Malaysia and the Ministry of Education Malaysia (Grant Nos. Q.J130000.2526.04H65).

A nanocomposite consisting of silica-coated magnetite and phenyl-functionalized graphene oxide for extraction of polycyclic aromatic hydrocarbon from aqueous matrices.

Science.gov (United States)

Mahpishanian, Shokouh; Sereshti, Hassan; Ahmadvand, Mohammad

2017-05-01

In this study, graphene oxide was covalently immobilized on silica-coated magnetite and then modified with 2-phenylethylamine to give a nanocomposite of type Fe 3 O 4 @SiO 2 @GO-PEA that can be applied to the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples. The resulting microspheres (Fe 3 O 4 @SiO 2 @GO-PEA) were characterized by Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), CHNS elemental analysis, and vibrating sample magnetometry (VSM) techniques. The adsorbent possesses the magnetic properties of Fe 3 O 4 nanoparticles that allow them easily to be separated by an external magnetic field. They also have the high specific surface area of graphene oxide which improves adsorption capacity. Desorption conditions, extraction time, amount of adsorbent, salt concentration, and pH were investigated and optimized. Following desorption, the PAHs were quantified by gas chromatography with flame ionization detection (GC-FID). The limits of detection (at an S/N ratio of 3) were achieved from 0.005 to 0.1μg/L with regression coefficients (R 2 ) higher than 0.9954. The relative standard deviations (RSDs) were below 5.8% (intraday) and 6.2% (inter-day), respectively. The method was successfully applied to the analysis of PAHs in environmental water samples where it showed recoveries in the range between 71.7% and 106.7% (with RSDs of 1.6% to 8.4%, for n=3). The results indicated that the Fe 3 O 4 @SiO 2 @GO-PEA microspheres had a great promise to extraction of PAHs from different water samples. Copyright © 2016. Published by Elsevier B.V.

Polyethyleneimine-modified superparamagnetic Fe3O4 nanoparticles: An efficient, reusable and water tolerance nanocatalyst

International Nuclear Information System (INIS)

Khoobi, Mehdi; Delshad, Tayebeh Modiri; Vosooghi, Mohsen; Alipour, Masoumeh; Hamadi, Hosein; Alipour, Eskandar; Hamedani, Majid Pirali; Sadat ebrahimi, Seyed Esmaeil; Safaei, Zahra; Foroumadi, Alireza; Shafiee, Abbas

2015-01-01

A novel magnetically separable catalyst was prepared based on surface modification of Fe 3 O 4 magnetic nanoparticle (MNPs) with polyethyleneimine (PEI) via covalent bonding. [3-(2,3-Epoxypropoxy)propyl]trimethoxysilane (EPO) was used as cross linker to bond PEI on the surface of MNPs with permanent stability in contrast to PEI coating via electrostatic interactions. The synthesized catalyst was characterized by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The catalyst show high efficiency for one-pot synthesis of 2-amino-3-cyano-4H-pyran derivatives via multi-component reaction (MCR). This procedure offers the advantages of green reaction media, high yield, short reaction time, easy purification of the products and simple recovery and reuse of the catalyst by simple magnetic decantation without significant loss of catalytic activity. - Graphical abstract: Covalently grafted polyethyleneimine on Fe 3 O 4 magnetic nanoparticles as easily reusable catalyst for the synthesis of various 4H-pyrans. - Highlights: • Polyethyleneimine modified Fe 3 O 4 via covalent bonding as a novel water tolerance catalyst. • The catalyst showed high efficiency for one-pot synthesis of 2-amino-3-cyano-4H-pyrans in water. • Catalysts could be easily recovered and reused for several times without a significant loss in their catalytic activity

Structural and magnetic characterization of maghemites prepared from Al-substituted magnetites

Directory of Open Access Journals (Sweden)

Marcelo Augusto Batista

2013-12-01

Full Text Available Synthetic aluminum-substituted maghemites were characterized by total chemical analysis, powder X-ray diffraction (XRD, Mössbauer spectroscopy (ME, and vibrating sample magnetometry (VSM. The aim was to determine the structural, magnetic, and hyperfine properties of γ-Fe2-xAl xO3 as the Al concentration is varied. The XRD results of the synthetic products were indexed exclusively as maghemite. Increasing Al for Fe substitution decreased the mean crystalline dimension and shifted all diffraction peaks to higher º2θ angles. The a0 dimension of the cubic unit cell decreased with increasing Al according to the equation a o = 0.8385 - 3.63 x 10-5 Al (R²= 0.94. Most Mössbauer spectra were composed of one sextet, but at the highest substitution rate of 142.5 mmol mol-1 Al, both a doublet and sextet were obtained at 300 K. All hyperfine parameters from the sub-spectra were consistent with high-spin Fe3+ (0.2 a 0.7 mms-1 and suggested a strong superparamagnetic component associated with the doublet. The magnetic hyperfine field of the sextets decreased with the amount of Al-substitution [Bhf (T = 49.751 - 0.1202Al; R² = 0.94] while the linewidth increased linearly. The saturation magnetization also decreased with increasing isomorphous substitution.

PEGylation of SPIONs by polycondensation reactions: a new strategy to improve colloidal stability in biological media

International Nuclear Information System (INIS)

Viali, Wesley Renato; Silva Nunes, Eloiza da; Santos, Caio Carvalho dos; Silva, Sebastião William da; Aragón, Fermin Herrera; Coaquira, José Antonio Huamaní; Morais, Paulo César; Jafelicci, Miguel

2013-01-01

In this study, we report on a new route of PEGylation of superparamagnetic iron oxide nanoparticles (SPIONs) by polycondensation reaction with carboxylate groups. Structural and magnetic characterizations were performed by X-ray diffractometry (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The XRD confirmed the spinel structure with a crystallite average diameter in the range of 3.5–4.1 nm in good agreement with the average diameter obtained by TEM (4.60–4.97 nm). The TGA data indicate the presence of PEG attached onto the SPIONs’ surface. The SPIONs were superparamagnetic at room temperature with saturation magnetization (M S ) from 36.7 to 54.1 emu/g. The colloidal stability of citrate- and PEG-coated SPIONs was evaluated by means of dynamic light scattering measurements as a function of pH, ionic strength, and nature of dispersion media (phosphate buffer and cell culture media). Our findings demonstrated that the PEG polymer chain length plays a key role in the coagulation behavior of the Mag-PEG suspensions. The excellent colloidal stability under the extreme conditions we evaluated, such as high ionic strength, pH near the isoelectric point, and cell culture media, revealed that suspensions comprising PEG-coated SPION, with PEG of molecular weight 600 and above, present steric stabilization attributed to the polymer chains attached onto the surface of SPIONs

Synthesis of amino-silane modified superparamagnetic Fe{sub 3}O{sub 4} nanoparticles and its application in immobilization of lipase from Pseudomonas fluorescens Lp1

Energy Technology Data Exchange (ETDEWEB)

Kanimozhi, S., E-mail: skanimo@gmail.com [Department of Biotechnology, Sathyabama University, Jeppiaar Nagar, Rajivgandhi Salai, Chennai 600119, Tamil Nadu (India); Perinbam, K. [Department of Plant Biology and Biotechnology, Nandanam Arts College (Men), Chennai 600035, Tamil Nadu (India)

2013-05-15

Highlights: ► Magnetic nanoparticles were synthesized by chemical co-precipitation method. ► Surface was functionalized with amino-silane and used for lipase immobilization. ► Characterized through TEM, SEM, XRD, FT-IR and VSM analysis. ► The functionalization and immobilization did not affect the magnetite properties. ► The immobilized lipase showed greater functional property than free lipase. - Abstract: Superparamagnetic nanoparticles (Fe{sub 3}O{sub 4}–magnetite) were prepared by chemical co-precipitation method and their surface was functionalized with 3-aminopropyltriethoxysilane via silanization reaction to obtain amino functionalized magnetic nanoparticles. The purified lipase from Pseudomonas fluorescens Lp1 was immobilized onto functionalized magnetite using glutaraldehyde as the coupling agent. The characterization of the nanoparticles was done by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, vibrating sample magnetometry and Fourier transformed infrared spectroscopy. The size of the magnetite was measured about 10–30 nm. The results of characterization study revealed the successful immobilization of lipase on to functionalized magnetite. The saturation magnetization of magnetic nanoparticles was found to be 28.34 emu/g whereas the immobilized magnetic nanoparticle was 17.074 emu/g. The immobilized lipase had greater activity at 50 °C and thermal stability upto 70 °C. It exhibited excellent reusability for 4 cycles and storage stability upto 15 days by retaining 75% of its initial activity.

PEGylation of SPIONs by polycondensation reactions: a new strategy to improve colloidal stability in biological media

Energy Technology Data Exchange (ETDEWEB)

Viali, Wesley Renato; Silva Nunes, Eloiza da; Santos, Caio Carvalho dos [Universidade Estadual Paulista, Laboratorio de Materiais Magneticos e Coloides, Departamento de Fisico-quimica, Instituto de Quimica (Brazil); Silva, Sebastiao William da; Aragon, Fermin Herrera; Coaquira, Jose Antonio Huamani; Morais, Paulo Cesar [Universidade de Brasilia, Instituto de Fisica, Nucleo de Fisica Aplicada (Brazil); Jafelicci, Miguel, E-mail: jafeli@iq.unesp.br [Universidade Estadual Paulista, Laboratorio de Materiais Magneticos e Coloides, Departamento de Fisico-quimica, Instituto de Quimica (Brazil)

2013-08-15

In this study, we report on a new route of PEGylation of superparamagnetic iron oxide nanoparticles (SPIONs) by polycondensation reaction with carboxylate groups. Structural and magnetic characterizations were performed by X-ray diffractometry (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The XRD confirmed the spinel structure with a crystallite average diameter in the range of 3.5-4.1 nm in good agreement with the average diameter obtained by TEM (4.60-4.97 nm). The TGA data indicate the presence of PEG attached onto the SPIONs' surface. The SPIONs were superparamagnetic at room temperature with saturation magnetization (M{sub S}) from 36.7 to 54.1 emu/g. The colloidal stability of citrate- and PEG-coated SPIONs was evaluated by means of dynamic light scattering measurements as a function of pH, ionic strength, and nature of dispersion media (phosphate buffer and cell culture media). Our findings demonstrated that the PEG polymer chain length plays a key role in the coagulation behavior of the Mag-PEG suspensions. The excellent colloidal stability under the extreme conditions we evaluated, such as high ionic strength, pH near the isoelectric point, and cell culture media, revealed that suspensions comprising PEG-coated SPION, with PEG of molecular weight 600 and above, present steric stabilization attributed to the polymer chains attached onto the surface of SPIONs.

Surface-Initiated Atom Transfer Radical Polymerization of Magnetite Nanoparticles with Statistical Poly(tert-butyl acrylate-poly(poly(ethylene glycol methyl ether methacrylate Copolymers

Directory of Open Access Journals (Sweden)

Patcharin Kanhakeaw

2015-01-01

Full Text Available This work presented the surface modification of magnetite nanoparticle (MNP with poly[(t-butyl acrylate-stat-(poly(ethylene glycol methyl ether methacrylate] copolymers (P[(t-BA-stat-PEGMA] via a surface-initiated “grafting from” atom transfer radical polymerization (ATRP. Loading molar ratio of t-BA to PEGMA was systematically varied (100 : 0, 75 : 25, 50 : 50, and 25 : 75, resp. such that the degree of hydrophilicity of the copolymers, affecting the particle dispersibility in water, can be fine-tuned. The reaction progress in each step of the synthesis was monitored via Fourier transform infrared spectroscopy (FTIR. The studies in the reaction kinetics indicated that PEGMA had higher reactivity than that of t-BA in the copolymerizations. Gel permeation chromatography (GPC indicated that the molecular weights of the copolymers increased with the increase of the monomer conversion. Transmission electron microscopy (TEM revealed that the particles were spherical with averaged size of 8.1 nm in diameter. Dispersibility of the particles in water was apparently improved when the copolymers were coated as compared to P(t-BA homopolymer coating. The percentages of MNP and the copolymer in the composites were determined via thermogravimetric analysis (TGA and their magnetic properties were investigated via vibrating sample magnetometry (VSM.

Performance of NiFe2O4-SiO2-TiO2 Magnetic Photocatalyst for the Effective Photocatalytic Reduction of Cr(VI in Aqueous Solutions

Directory of Open Access Journals (Sweden)

Mike O. Ojemaye

2017-01-01

Full Text Available Investigation into the reduction of Cr(VI in aqueous solution was carried out through some batch photocatalytic studies. The photocatalysts used were silica coated nickel ferrite nanoparticles (NiFe2O4-SiO2, nickel ferrite titanium dioxide (NiFe2O4-TiO2, nickel ferrite silica titanium dioxide (NiFe2O4-SiO2-TiO2, and titanium dioxide (TiO2. The characterization of the materials prepared via stepwise synthesis using coprecipitation and sol-gel methods were carried out with the aid of X-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, Fourier transform infrared (FTIR spectroscopy, thermal gravimetric analysis (TGA, and vibrating sample magnetometry (VSM. The reduction efficiency was studied as a function of pH, photocatalyst dose, and contact time. The effects of silica interlayer between the magnetic photocatalyst materials reveal that reduction efficiency of NiFe2O4-SiO2-TiO2 towards Cr(VI was higher than that of NiFe2O4-TiO2. However, TiO2 was observed to have the highest reduction efficiency at all batch photocatalytic experiments. Kinetics study shows that photocatalytic reduction of Cr(VI obeyed Langmuir-Hinshelwood model and first-order rate kinetics. Regenerability study also suggested that the photocatalyst materials can be reused.

Iron-rich (Fe1-x-yNixCoy)88Zr7B4Cu1 nanocrystalline magnetic materials for high temperature applications with minimal magnetostriction

Science.gov (United States)

Martone, Anthony; Dong, Bowen; Lan, Song; Willard, Matthew A.

2018-05-01

As inductor technology advances, greater efficiency and smaller components demand new core materials. With recent developments of nanocrystalline magnetic materials, soft magnetic properties of these cores can be greatly improved. FeCo-based nanocrystalline magnetic alloys have resulted in good soft magnetic properties and high Curie temperatures; however, magnetoelastic anisotropies persist as a main source of losses. This investigation focuses on the design of a new Fe-based (Fe,Ni,Co)88Zr7B4Cu1 alloy with reduced magnetostriction and potential for operation at elevated temperatures. The alloys have been processed by arc melting, melt spinning, and annealing in a protective atmosphere to produce nanocrystalline ribbons. These ribbons have been analyzed for structure, hysteresis, and magnetostriction using X-Ray diffraction, vibrating sample magnetometry (VSM), and a home-built magnetostriction system, respectively. In addition, Curie temperatures of the amorphous phase were analyzed to determine the best performing, high-temperature material. Our best result was found for a Fe77Ni8.25Co2.75Zr7B4Cu1 alloy with a 12 nm average crystallite size (determined from Scherrer broadening) and a 2.873 Å lattice parameter determined from the Nelson-Riley function. This nanocrystalline alloy possesses a coercivity of 10 A/m, magnetostrictive coefficient of 4.8 ppm, and amorphous phase Curie temperature of 218°C.

Single flexible nanofiber to achieve simultaneous photoluminescence-electrical conductivity bifunctionality.

Science.gov (United States)

Sheng, Shujuan; Ma, Qianli; Dong, Xiangting; Lv, Nan; Wang, Jinxian; Yu, Wensheng; Liu, Guixia

2015-02-01

In order to develop new-type multifunctional composite nanofibers, Eu(BA)3 phen/PANI/PVP bifunctional composite nanofibers with simultaneous photoluminescence and electrical conductivity have been successfully fabricated via electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of Eu(BA)3 phen and polyaniline (PANI). X-Ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fluorescence spectroscopy and a Hall effect measurement system are used to characterize the morphology and properties of the composite nanofibers. The results indicate that the bifunctional composite nanofibers simultaneously possess excellent photoluminescence and electrical conductivity. Fluorescence emission peaks of Eu(3+) ions are observed in the Eu(BA)3 phen/PANI/PVP photoluminescence-electrical conductivity bifunctional composite nanofibers. The electrical conductivity reaches up to the order of 10(-3)  S/cm. The luminescent intensity and electrical conductivity of the composite nanofibers can be tuned by adjusting the amounts of Eu(BA)3 phen and PANI. The obtained photoluminescence-electrical conductivity bifunctional composite nanofibers are expected to possess many potential applications in areas such as microwave absorption, molecular electronics, biomedicine and future nanomechanics. More importantly, the design concept and construction technique are of universal significance to fabricate other bifunctional one-dimensional naonomaterials. Copyright © 2014 John Wiley & Sons, Ltd.

High-field torque magnetometry for investigating magnetic anisotropy in Mn{sub 12}-acetate nanomagnets

Energy Technology Data Exchange (ETDEWEB)

Cornia, Andrea E-mail: acornia@unimo.it; Affronte, Marco; Gatteschi, Dante; Jansen, Aloysius G.M.; Caneschi, Andrea; Sessoli, Roberta

2001-05-01

The single-molecule superparamagnet [Mn{sub 12}O{sub 12}(OAc){sub 16}(H{sub 2}O){sub 4}]{center_dot}2AcOH{center_dot}4H{sub 2}O (Mn{sub 12}-acetate) has attracted considerable attention because it shows exceedingly slow paramagnetic relaxation at low temperature. The cluster has S{sub 4} symmetry in the solid state and comprises four Mn(IV) ions (S=((3)/(2))) and eight Mn(III) ions (S=2) which are magnetically coupled to give an S=10 ground state. The ground manifold is largely split in zero magnetic field and many efforts have been spent to determine the zero-field splitting (zfs) parameters {alpha}, {beta} and {gamma} appearing in the fourth-order spin-Hamiltonian H={alpha}S{sub z}{sup 2}+{beta}S{sub z}{sup 4}+{gamma}(S{sub +}{sup 4}+S{sub -}{sup 4})+{mu}{sub B}B{center_dot}g{center_dot}S. These are of paramount importance for defining the magnetic anisotropy of the cluster, which in turn determines the slow relaxation of the magnetization and quantum tunneling effects at low temperatures. We want to show that cantilever torque magnetometry in high fields is a suitable technique for determining second- and fourth-order anisotropic contributions in high-spin molecules, such as Mn{sub 12}-acetate. The main advantage of the method lies in its high sensitivity which allows to use very small single crystals. Torque curves have been recorded at 4.2 K by applying the magnetic field (0-28 T) very close to the ab-plane of the tetragonal unit cell. The zfs parameters obtained by this procedure [{alpha}=-0.389(5) cm{sup -1} and {beta}=-8.4(5)x10{sup -4} cm{sup -1}] are in excellent agreement with those determined by spectroscopic techniques, such as high-frequency EPR and inelastic neutron scattering.

Angular dependence of the disorder crossover in the vortex lattice of Bi2.15Sr1.85CaCu2O8+δ by muon spin rotation and torque magnetometry

International Nuclear Information System (INIS)

Aegerter, C.M.; Hofer, J.; Savic, I.M.; Keller, H.; Lee, S.L.; Ager, C.; Lloyd, S.H.; Forgan, E.M.

1998-01-01

Using the techniques of muon spin rotation and torque magnetometry, we investigate the crossover field B cr in Bi 2.15 Sr 1.85 Ca 1 Cu 2 O 8+δ at which the vortex lattice becomes disordered along the field direction. It is found that B cr scales as the projection of the applied field along the perpendicular to the superconducting planes. This has the implication that a field large enough to give a disordered lattice when applied perpendicular to the planes, can give a well-ordered vortex-line lattice for angles of the field to the c axis greater than a critical value. copyright 1998 The American Physical Society

Determination of the Antarctic region active margin basement by using integration of the information coming from the multichannel seismic analysis and the magnetometry; Determinacao do embasamento da margen ativa da regiao Antartica pela integracao de informacoes provenientes da sismica multicanal e da magnetometria

Energy Technology Data Exchange (ETDEWEB)

Torres, Luiz Carlos [Diretoria de Hidrografia e Navegacao, XX (Brazil); Gomes, Benedito Souza [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Gamboa, Luiz Antonio P. [Universidade Federal Fluminense, Niteroi, RJ (Brazil)

1999-07-01

Geophysical measurements were carried out in the Western Margin of the Antarctic Peninsula and Bransfield Strait by the Brazilian Antarctic Program during the summers of 1987 and 1988. The present work, using a continued seismic multi channel and magnetometry data profile crossing the area, intends to present a two-dimensional model of the interface sediment/basement and contribute to the understanding of the complex geology verified in the studying area. By this model, the main provinces of the are (Deep Ocean, South Shetland Trench, Accretionary Prism, Volcanic Arc South Shetland Islands and Bransfield Basin) could be determined. The seismic and magnetic measurements information when superposed can attribute more consistencies to the interpreted basement; although each method has its particular resolution. This way, when the seismic interpretation was not possible due to complex structures disposition, magnetic measurements could offer good estimation about basement depth. The fit between both methods (seismic and magnetic measurements) was reasonable both on the oceanic basin and in the region of Bransfield Strait. The magnetometry, as as well seismic, was sensible to the dip of Drake Plate at South Shetland Trench and the Intrusive occurrence at Bransfield Basin axis. (author)

Efficient solar light-driven degradation of Congo red with novel Cu-loaded Fe3O4@TiO2 nanoparticles.

Science.gov (United States)

Arora, Priya; Fermah, Alisha; Rajput, Jaspreet Kaur; Singh, Harminder; Badhan, Jigyasa

2017-08-01

In this work, Cu-loaded Fe 3 O 4 @TiO 2 core shell nanoparticles were prepared in a single pot by coating of TiO 2 on Fe 3 O 4 nanoparticles followed by Cu loading. X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), thermogravimetric analysis (TGA), Brunauer-Emmett- Teller (BET), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and valence band X-ray photoelectron spectroscopy (VB XPS) techniques were used for characterization of as prepared nanoparticles. Synergism between copper and titania was evaluated by studying the solar light-driven photodegradation of Congo red dye solution in the presence of Fe 3 O 4 @TiO 2 nanoparticles on one side and Cu-loaded Fe 3 O 4 @TiO 2 nanoparticles on the other side. The latter performed better than the former catalyst, indicating the enhanced activity of copper-loaded catalyst. Further photodegradation was studied by three means, i.e., under ultraviolet (UV), refluxing, and solar radiations. Cu-loaded Fe 3 O 4 @TiO 2 enhanced the degradation efficiency of Congo red dye. Thus, Cu act possibly by reducing the band gap of TiO 2 and widening the optical response of semiconductor, as a result of which solar light could be used to carry out photocatalysis. Graphical abstract Photodegradation of congo red over Cu-loaded Fe 3 O 4 @TiO 2 nanoparticles.

Size-controlled synthesis of NiFe2O4 nanospheres via a PEG assisted hydrothermal route and their catalytic properties in oxidation of alcohols by periodic acid

International Nuclear Information System (INIS)

Paul, Bappi; Purkayastha, Debraj Dhar; Dhar, Siddhartha Sankar

2016-01-01

Graphical abstract: - Highlights: • Hydrothermal synthesis of NiFe 2 O 4 NPs with (C 4 H 9 ) 3 N as hydroxylating agent. • PEG 4000 was used as surfactant to control sizes of NPs. • The TEM images revealed the material to be spherical in shape with sizes 2–10 nm. • NiFe 2 O 4 was used as recyclable catalyst for oxidation of alcohols by periodic acid. - Abstract: A novel and facile approach for synthesis of spinel nickel ferrites (NiFe 2 O 4 ) nanoparticles (NPs) employing homogeneous chemical precipitation followed by hydrothermal heating is reported. The synthesis involves use of tributylamine (TBA) as a hydroxylating agent in synthesis of nickel ferrites. Polyethylene glycol (PEG) 4000 was used as surfactant. As-synthesized NiFe 2 O 4 NPs were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 adsorption–desorption isotherm (BET) and vibrating sample magnetometry (VSM). The XRD pattern revealed formation of cubic face-centered NiFe 2 O 4 and TEM image showed spherical particles of sizes 2–10 nm. These NiFe 2 O 4 NPs were used as magnetically recoverable catalyst in oxidation of cyclic alcohols to their corresponding aldehydes by periodic acid. This eco-friendly procedure affords products in very high yield and selectivity. The reusability of the catalyst is proved to be noteworthy as the material exhibits no significant changes in its catalytic activity even after five cycles of reuse.

Synthesis of MnxGa1−xFe2O4 magnetic nanoparticles by thermal decomposition method for medical diagnosis applications

International Nuclear Information System (INIS)

Sánchez, Javier; Cortés-Hernández, Dora Alicia; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Reyes-Rodríguez, Pamela Yajaira; Jasso-Terán, Rosario Argentina; Bartolo-Pérez, Pascual; De-León-Prado, Laura Elena

2017-01-01

In this work, the synthesis of Mn x Ga 1−x Fe 2 O 4 (x=0–1) nanosized particles by thermal decomposition method, using tetraethylene glycol (TEG) as a reaction medium, has been performed. The crystalline structure of the inverse spinel obtained in all the cases was identified by X-ray diffraction (XRD). Vibration sample magnetometry (VSM) was used to evaluate the magnetic properties of ferrites and to demonstrate their superparamagnetic behavior and the increase of magnetization values due to the Mn 2+ ions incorporation into the FeGa 2 O 4 structure. Transmission electron microscopy, energy dispersive spectroscopy (TEM-EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the obtained magnetic nanoparticles (MNPs). These MNPs showed a near spherical morphology, an average particle size of 5.6±1.5 nm and a TEG coating layer on their surface. In all the cases MNPs showed no response when submitted to an alternating magnetic field (AMF, 10.2 kA/m, 354 kHz) using magnetic induction tests. These results suggest that the synthesized nanoparticles can be potential candidates for their use in biomedical areas. - Highlights: • Superparamagnetic NPs of Mn x Ga 1−x Fe 2 O 4 were synthesized by thermal decomposition. • Saturation magnetization of MnGaFe 2 O 4 increases as Mn ions are increased. • Nanoparticles have a nanometric size of 5.6 nm and show no heating ability.

Structural, catalytic and magnetic properties of Cu{sub 1-X}Co{sub X}Fe{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Briceno, Sarah, E-mail: sbriceno@ivic.gob.ve [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Del Castillo, Hector [Laboratorio de Cinetica y Catalisis, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101-A (Venezuela, Bolivarian Republic of); Sagredo, V. [Laboratorio de Magnetismo, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101-A (Venezuela, Bolivarian Republic of); Bramer-Escamilla, Werner; Silva, Pedro [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of)

2012-12-15

Highlights: Black-Right-Pointing-Pointer Cu{sub 1-X}Co{sub X}Fe{sub 2}O{sub 4} ferrite synthesized by sol-gel auto-combustion method. Black-Right-Pointing-Pointer Structural identification, magnetic and catalytic properties were investigated. Black-Right-Pointing-Pointer Characterization by TGA, DTA, XRD, SEM, TEM and VSM techniques. Black-Right-Pointing-Pointer Magnetic properties decrease with the increase of Cu{sup 2+} doping. Black-Right-Pointing-Pointer The selective conversion to N{sub 2} is higher for Cu-Co mixed ferrites. - Abstract: Copper substituted cobalt ferrite Cu{sub 1-X}Co{sub X}Fe{sub 2}O{sub 4} (0 {<=}x {<=} 1) have been synthesized using sol-gel auto combustion method with citric acid as fuel. Structural identification, magnetic and catalytic properties were investigated using thermogravimetric and differential thermal analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and their application in the selective catalytic reduction of NOx were studied. Analysis of structural properties reveals that all samples have cubic spinel structure. Room temperature magnetic hysteresis measurements as a function of magnetic field infer that the magnetic properties decrease with Cu{sup 2+} doping which may be due to the difference of the magnetic moment of Cu{sup 2+} and Co{sup 2+} ions. The higher activity of the samples in NO selective reduction to N{sub 2} occurs at 350 Degree-Sign C, reaching a maximum of 38% NO conversion and 95% of selective conversion to N{sub 2}. The compositions containing both Cu{sup 2+} and Co{sup 2+} ions are more active to the products selectivity to N{sub 2}, suggesting a synergistic effect on the active surface of ferrite and the effect of Co{sup 2+} is more pronounced than Cu{sup 2+} towards NO conversion.

Magnetic molecularly imprinted polymer nanoparticles for the solid-phase extraction of paracetamole from plasma samples, followed its determination by HPLC

International Nuclear Information System (INIS)

Azodi-Deilami, Saman; Najafabadi, Alireza Hassani; Asadi, Ebadullah; Abdouss, Majid; Kordestani, Davood

2014-01-01

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamole. The m-MIPs were prepared from magnetite (Fe 3 O 4 ) as the magnetic component, paracetamole as the template, methacrylic acid as a functional monomer, and 2-(methacrylamido) ethyl methacrylate as a cross-linker. The m-MIPs were then characterized by transmission electron microscopy, FT-IR spectroscopy, X-ray diffraction and vibrating sample magnetometry. The m-MIPs were applied to the extraction of paracetamole from human blood plasma samples. Following its elution from the column loaded with the m-MIPs with an acetonitrile-buffer (9:1) mixture, it was submitted to HPLC analysis. Paracetamole can be quantified by this method in the 1 μg L −1 to 300 μg L −1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.17 and 0.4 μg L −1 . The preconcentration factor of the m-MIPs is 40. The HPLC method shows good precision (4.5 % at 50 μg L −1 levels) and recoveries (between 83 and 91 %) from spiked plasma samples. (author)

Vibrating sample magnetometer 2D and 3D magnetization effects associated with different initial magnetization states

Directory of Open Access Journals (Sweden)

Ronald E. Lukins

2017-05-01

Full Text Available Differences in VSM magnetization vector rotation associated with various initial magnetization states were demonstrated. Procedures and criteria were developed to select sample orientation and initial magnetization states to allow for the combination of two different 2D measurements runs (with the same field profiles to generate a dataset that can be representative of actual 3D magnetization rotation. Nickel, cast iron, and low moment magnetic tape media were used to demonstrate these effects using hysteresis and remanent magnetization test sequences. These results can be used to generate 2D and 3D magnetic properties to better characterize magnetic phenomena which are inherently three dimensional. Example applications are magnetic tape-head orientation sensitivity, reinterpretation of 3D coercivity and other standard magnetic properties, and multi-dimensional shielding effectiveness.

Facile synthesis and enhanced magnetic, photocatalytic properties of one-dimensional Ag@Fe{sub 3}O{sub 4}-TiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Jia, Xiaohua, E-mail: xhjia2003@126.com [School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Dai, Rongrong; Lian, Dandan; Han, Song [School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Wu, Xiangyang, E-mail: wuxy@ujs.edu.cn [School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Song, Haojie [Institute of Polymer Materials, School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China)

2017-01-15

Highlights: • One-dimensional triple heterostructure Ag@Fe{sub 3}O{sub 4}-TiO{sub 2} was successfully achieved by a facile co-precipitation and chemical-solution-deposition process method. • One-dimensional triple heterostructure Ag@Fe{sub 3}O{sub 4}-TiO{sub 2} exhibited enhanced photocatalytic properties and can be easily recovered by an extemal magnetic field. • The mechanisms for the enhanced photocatalytic effect of the heterostructure were discussed. - Abstract: Fe{sub 3}O{sub 4}-TiO{sub 2} heterostructures were synthesized through co-precipitation method based on TiO{sub 2} nanobelts. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometry (VSM) were used to characterize the heterostructure nanocomposites. The results of XRD proved that the TiO{sub 2} nanobelt was anatase which was the most suitable crystal form for photocatalysis. SEM and TEM analysis indicated that Fe{sub 3}O{sub 4} nanoparticles were adhere to TiO{sub 2} nanobelts which have one-dimensional structure with 100–200 nm in width. The VSM measurements showed that the photocatalyst can be easily recovered by an extemal magnetic field. X-ray photoelectron spectroscopy (XPS) of Ag@Fe{sub 3}O{sub 4}-TiO{sub 2} nanocomposites studies confirm that Ag is in Ag{sup 0} state. Finally, the photodegradation of rhodamine B (RhB) by the obtained magnetic photocatalyst was investigated via UV–vis absorption spectra. The photocatalytic activity of the composites was observed to be lower compared to bare TiO{sub 2} due to the higher degree of recombination reactions after combined with Fe{sub 3}O{sub 4} nanoparticles. After coated the composite of 15% Fe{sub 3}O{sub 4}-TiO{sub 2} with Ag, the new nanocomposite of Ag@Fe{sub 3}O{sub 4}-TiO{sub 2} can be easily recovered after photocatalysis by an extemal magnetic field and showed enhanced photocatalytic activity. The mechanisms for the exhibited enhanced photocatalytic effect of

Single and double-layer composite microwave absorbers with hexaferrite BaZn{sub 0.6}Zr{sub 0.3}X{sub 0.3}Fe{sub 10.8}O{sub 19} (X = Ti, Ce, Sn) powders

Energy Technology Data Exchange (ETDEWEB)

Afghahi, Seyyed Salman Seyyed [Department of Materials Science and Engineering, Imam Hossein University, Tehran (Iran, Islamic Republic of); Jafarian, Mojtaba, E-mail: m.jafarian@srbiau.ac.ir [Young Researchers and Elites Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Atassi, Yomen [Department of Applied Physics, Higher Institute for Applied Sciences and Technology, Damascus (Syrian Arab Republic); Stergiou, Charalampos A. [Lab. of Inorganic Materials, Centre for Research and Technology Hellas, 57001, Thermi (Greece)

2017-01-15

In the present study, substituted barium hexaferrites with the composition BaZn{sub 0.6}Zr{sub 0.3} × {sub 0.3}Fe{sub 10.8}O{sub 19} (where X = Ti, Ce, Sn) are prepared with the solid-state reaction method. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and network analysis techniques are used to analyze the crystal phases, morphology, static magnetic and microwave absorption properties, respectively. Based on the recorded results, barium hexaferrite is the major phase obtained after milling of the powders for 20 h, followed by calcination at 1000 °C for 5 h. The morphology of the particles of the substituted ferrite samples is plate-like with hexagonal shape. The microwave absorption in the X-band of epoxy composites loaded with the ferrite fillers, either separately, in pairs or all together, has been extensively investigated. Multicomponent composites filled with the new hexaferrites under study are promising candidates for electromagnetic absorbers in the 8–12 GHz range. It is found that single-layer absorbers of 5 mm thickness with 45 wt% of a binary (Sn and Ti-doped hexaferrite) or ternary filler mixture exhibit the maximum bandwidth of 2.7 GHz at the level of −10 dB or maximum losses of 26.4 dB at 10.8 GHz, respectively. - Highlights: • Preparation of substituted hexaferrites via mechanical activation. • We designed a broad band microwave absorber with mixing powders. • We designed single layer absorber with RL{sub min} = −26.4 dB and 1.6 GHz bandwidth. • We designed double layer absorbers, as monoband absorbers at a matching frequency.

Polystyrene/magnetite nanocomposite synthesis and characterization: investigation of magnetic and electrical properties for using as microelectromechanical systems (MEMS

Directory of Open Access Journals (Sweden)

Omidi Mohammad Hassan

2017-02-01

Full Text Available In this work, a novel polystyrene/Fe3O4 nanocomposite prepared by in-situ method is presented. Magnetic Fe3O4 nanoparticles were encapsulated by polystyrene. The FT-IR spectra confirmed polystyrene/Fe3O4 nanocomposite preparation. The electrical properties of prepared nanocomposite were investigated by cyclic voltammetry (CV. The CV analysis showed good electrical conductivity of the synthesized nanocomposite. Magnetic properties of the nanocomposite were studied by vibrating sample magnetometer (VSM. The VSM analysis confirmed magnetic properties of the nanocomposite. The morphology and the size of the synthesized nanocomposite were investigated by field emission scanning electron microscope (FESEM. According to the VSM and CV results, such nanocomposite can be used in microelectromechanical systems.

Contributed review: camera-limits for wide-field magnetic resonance imaging with a nitrogen-vacancy spin sensor

DEFF Research Database (Denmark)

Wojciechowski, Adam M.; Karadas, Mürsel; Huck, Alexander

2018-01-01

Sensitive, real-time optical magnetometry with nitrogen-vacancy centers in diamond relies on accurate imaging of small (≪10−2), fractional fluorescence changes across the diamond sample. We discuss the limitations on magnetic field sensitivity resulting from the limited number of photoelectrons t......-level sensitivity in 1 s of a combined exposure. Finally, we demonstrate the results obtained with a lock-in camera that paves the way for real-time, wide-field magnetometry at the nanotesla level and with a micrometer resolution....

Iron oxides in human spleen.

Science.gov (United States)

Kopáni, Martin; Miglierini, Marcel; Lančok, Adriana; Dekan, Július; Čaplovicová, Mária; Jakubovský, Ján; Boča, Roman; Mrazova, Hedviga

2015-10-01

Iron is an essential element for fundamental cell functions and a catalyst for chemical reactions. Three samples extracted from the human spleen were investigated by scanning (SEM) and transmission electron microscopy (TEM), Mössbauer spectrometry (MS), and SQUID magnetometry. The sample with diagnosis of hemosiderosis (H) differs from that referring to hereditary spherocytosis and the reference sample. SEM reveals iron-rich micrometer-sized aggregate of various structures-tiny fibrils in hereditary spherocytosis sample and no fibrils in hemochromatosis. Hematite and magnetite particles from 2 to 6 μm in TEM with diffraction in all samples were shown. The SQUID magnetometry shows different amount of diamagnetic, paramagnetic and ferrimagnetic structures in the tissues. The MS results indicate contribution of ferromagnetically split sextets for all investigated samples. Their occurrence indicates that at least part of the sample is magnetically ordered below the critical temperature. The iron accumulation process is different in hereditary spherocytosis and hemosiderosis. This fact may be the reason of different iron crystallization.

Novel Functionalized Polythiophene-Coated Fe3O4 Nanoparticles for Magnetic Solid-Phase Extraction of Phthalates

Directory of Open Access Journals (Sweden)

Siti Nor Atika Baharin

2016-04-01

Full Text Available Poly(phenyl-(4-(6-thiophen-3-yl-hexyloxy-benzylidene-amine (P3TArH was successfully synthesized and coated on the surface of Fe3O4 magnetic nanoparticles (MNPs. The nanocomposites were characterized by Fourier transform infra-red (FTIR, X-ray diffractometry (XRD, Brunauer-Emmett-Teller (BET surface area analysis, analyzer transmission electron microscopy (TEM and vibrating sample magnetometry (VSM. P3TArH-coated MNPs (MNP@P3TArH showed higher capabilities for the extraction of commonly-used phthalates and were optimized for the magnetic-solid phase extraction (MSPE of environmental samples. Separation and determination of the extracted phthalates, namely dimethyl phthalate (DMP, diethyl phthalate (DEP, dipropyl phthalate (DPP, dibutyl phthalate (DBP, butyl benzyl phthalate (BBP, dicyclohexyl phthalate (DCP, di-ethylhexyl phthalate (DEHP and di-n-octyl phthalate (DNOP, were conducted by a gas chromatography-flame ionization detector (GC-FID. The best working conditions were as follows; sample at pH 7, 30 min extraction time, ethyl acetate as the elution solvent, 500-µL elution solvent volumes, 10 min desorption time, 10-mg adsorbent dosage, 20-mL sample loading volume and 15 g·L−1 concentration of NaCl. Under the optimized conditions, the analytical performances were determined with a linear range of 0.1–50 µg·L−1 and a limit of detection at 0.08–0.468 µg·L−1 for all of the analytes studied. The intra-day (n = 7 and inter-day (n = 3 relative standard deviations (RSD% of three replicates were each demonstrated in the range of 3.7–4.9 and 3.0–5.0, respectively. The steadiness and reusability studies suggested that the MNP@P3TArH could be used up to five cycles. The proposed method was executed for the analysis of real water samples, namely commercial bottled mineral water and bottled fresh milk, whereby recoveries in the range of 68%–101% and RSD% lower than 7.7 were attained.

In-situ investigation of martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature

DEFF Research Database (Denmark)

Villa, Matteo; Hansen, Mikkel Fougt; Pantleon, Karen

2013-01-01

Martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature was investigated with Vibrating Sample Magnetometry. The investigation reports the stabilization of retained austenite in quenched samples during storage at room temperature and reveals the thermally activated nature...

Size-controlled synthesis of NiFe{sub 2}O{sub 4} nanospheres via a PEG assisted hydrothermal route and their catalytic properties in oxidation of alcohols by periodic acid

Energy Technology Data Exchange (ETDEWEB)

Paul, Bappi; Purkayastha, Debraj Dhar; Dhar, Siddhartha Sankar, E-mail: ssd_iitg@hotmail.com

2016-05-01

Graphical abstract: - Highlights: • Hydrothermal synthesis of NiFe{sub 2}O{sub 4} NPs with (C{sub 4}H{sub 9}){sub 3}N as hydroxylating agent. • PEG 4000 was used as surfactant to control sizes of NPs. • The TEM images revealed the material to be spherical in shape with sizes 2–10 nm. • NiFe{sub 2}O{sub 4} was used as recyclable catalyst for oxidation of alcohols by periodic acid. - Abstract: A novel and facile approach for synthesis of spinel nickel ferrites (NiFe{sub 2}O{sub 4}) nanoparticles (NPs) employing homogeneous chemical precipitation followed by hydrothermal heating is reported. The synthesis involves use of tributylamine (TBA) as a hydroxylating agent in synthesis of nickel ferrites. Polyethylene glycol (PEG) 4000 was used as surfactant. As-synthesized NiFe{sub 2}O{sub 4} NPs were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} adsorption–desorption isotherm (BET) and vibrating sample magnetometry (VSM). The XRD pattern revealed formation of cubic face-centered NiFe{sub 2}O{sub 4} and TEM image showed spherical particles of sizes 2–10 nm. These NiFe{sub 2}O{sub 4} NPs were used as magnetically recoverable catalyst in oxidation of cyclic alcohols to their corresponding aldehydes by periodic acid. This eco-friendly procedure affords products in very high yield and selectivity. The reusability of the catalyst is proved to be noteworthy as the material exhibits no significant changes in its catalytic activity even after five cycles of reuse.

Preparation, Characterization and Tests of Incorporation in Stem Cells of Superparamagnetic Iron Oxide

International Nuclear Information System (INIS)

Haddad, P S; Britos, T N; Li, L M; Li, L D S

2015-01-01

Superparamagnetic iron oxide nanoparticles (SPIONs) have been produced and used as contrast-enhancing agents in magnetic resonance imaging (MRI) for diagnostic use in a wide range of maladies including cardiovascular, neurological disorders, and cancer. The reasons why these SPIONs are attractive for medical purposes are based on their important and unique features. The large surface area of the nanoparticles and their manipulation through an external magnetic field are features that allow their use for carrying a large number of molecules such as biomolecules or drugs. In this scenario, the present work reports on the synthesis and characterization of SPIONs and in vitro MRI experiments to increase their capacity as probes for MRI applications on stem cells therapy. Initially, the SPIONs were prepared through the co-precipitation method using ferrous and ferric chlorides in acidic solution. The SPIONs were coated with two thiolmolecules such as mercaptosuccinic acid (MSA) and cysteine (Cys) (molar ratio SPIONs:ligand = 1:20), leading to the formation of a stable aqueous dispersion of thiolated nanoparticles (SH-SPIONs). The SH-SPIONs were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The results showed that the SH-SPIONs have a mean diameter of 14 nm and display superparamagnetic behavior at room temperature. Preliminary tests of incorporation of SH-SPIONs were evaluated stem cells. The results showed that the thiolated nanoparticles have no toxic effects for stem cells and successfully internalized and enhance the contrast in MRI. (paper)

Novel Magnetic Zinc Oxide Nanotubes for Phenol Adsorption: Mechanism Modeling

Directory of Open Access Journals (Sweden)

Marwa F. Elkady

2017-11-01

Full Text Available Considering the great impact of a material’s surface area on adsorption processes, hollow nanotube magnetic zinc oxide with a favorable surface area of 78.39 m2/g was fabricated with the assistance of microwave technology in the presence of poly vinyl alcohol (PVA as a stabilizing agent followed by sonic precipitation of magnetite nano-particles. Scanning electron microscopy (SEM and transmission electron microscopy (TEM micrographs identified the nanotubes’ morphology in the synthesized material with an average aspect ratio of 3. X-ray diffraction (XRD analysis verified the combination of magnetite material with the hexagonal wurtzite structure of ZnO in the prepared material. The immobilization of magnetite nanoparticles on to ZnO was confirmed using vibrating sample magnetometry (VSM. The sorption affinity of the synthesized magnetic ZnO nanotube for phenolic compounds from aqueous solutions was examined as a function of various processing factors. The degree of acidity of the phenolic solution has great influence on the phenol sorption process on to magnetic ZnO. The calculated value of ΔH0 designated the endothermic nature of the phenol uptake process on to the magnetic ZnO nanotubes. Mathematical modeling indicated a combination of physical and chemical adsorption mechanisms of phenolic compounds on to the fabricated magnetic ZnO nanotubes. The kinetic process correlated better with the second-order rate model compared to the first-order rate model. This result indicates the predominance of the chemical adsorption process of phenol on to magnetic ZnO nanotubes.

NiFe{sub 2}O{sub 4}/activated carbon nanocomposite as magnetic material from petcoke

Energy Technology Data Exchange (ETDEWEB)

Briceño, Sarah, E-mail: sbriceno@ivic.gob.ve [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Brämer-Escamilla, W., E-mail: wbramer@ivic.gob.ve [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Silva, P. [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); García, J.; Del Castillo, H.; Villarroel, M. [Laboratorio de Cinética y Catálisis, Departamento de Química, Facultad de Ciencias, Universidad de Los Andes ULA, Mérida 5101-A (Venezuela, Bolivarian Republic of); Rodriguez, J.P. [Laboratorio de Microscopia Electrónica. Instituto de Estudios Científicos y Tecnológicos IDECYT. Apartado 47925 - Caracas 1041-A (Venezuela, Bolivarian Republic of); Ramos, M.A.; Morales, R. [Instituto Zuliano de Investigaciones Tecnológicas INZIT. Apdo. Postal 331. La Cañada-Maracaibo (Venezuela, Bolivarian Republic of); Diaz, Y. [Centro de Química, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of)

2014-06-01

Nickel ferrite (NiFe{sub 2}O{sub 4}) was supported on activated carbon (AC) from petroleum coke (petcoke). Potassium hydroxide (KOH) was employed with petcoke to produce activated carbon. NiFe{sub 2}O{sub 4} were synthesized using PEG-Oleic acid assisted hydrothermal method. The structural and magnetic properties were determined using thermogravimetric and differential thermal analysis (TGA–DTA), X-ray diffraction (XRD), Fourier Transform Infrared (IR-FT), surface area (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). XRD analysis revealed the cubic spinel structure and ferrite phase with high crystallinity. IR-FT studies showed that chemical modification promoted the formation of surface oxygen functionalities. Morphological investigation by SEM showed conglomerates of spherical nanoparticles with an average particle size of 72 nm and TEM showed the formation of NiFe{sub 2}O{sub 4}/carbon nanofibers. Chemical modification and activation temperature of 800 °C prior to activation dramatically increased the BET surface area of the resulting activated carbon to 842.4 m{sup 2}/g while the sulfur content was reduced from 6 to 1%. Magnetic properties of nanoparticles show strong dependence on the particle size. - Highlights: • TEM showed the formation of NiFe{sub 2}O{sub 4}/carbon nanofibers. • Nanoparticles were supported on the activated carbon from petcoke. • Activation dramatically increased the BET surface area to 842 m{sup 2}/g. • Magnetic properties show strong dependence on the particle size. • Sulphur content was reduced from 6 to 1% with the petcoke activation.

Synthesis and characterization of barium ferrite–silica nanocomposites

International Nuclear Information System (INIS)

Aguilar-González, M.A.; Mendoza-Suárez, G.; Padmasree, K.P.

2013-01-01

In this work, we prepared barium ferrite-silica (BaM-SiO 2 ) nanocomposites of different molar ratios by high-energy ball milling, followed by heat-treatment at different temperatures. The microstructure, morphology and magnetic properties were characterized for different synthesis conditions by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results indicate that 15 h of milling was enough to avoid the generation of hematite phase and to get a good dispersion of barium ferrite particles in the ceramic matrix. For milling periods beyond 15 h and heat treatment above 900 °C, the XRD patterns showed the presence of hematite phase caused by the decomposition of BaM. The agglomerate size observed through SEM analysis was around 150 nm with a good BaM dispersion into the SiO 2 matrix. The highest saturation magnetization (Ms) value obtained was 43 emu/g and the corresponding coercivity (Hc) value of 3.4 kOe for the composition 60BaM-40SiO 2 milled for 15 h and heat treated at 900 °C. This coercivity value is acceptable for the application in magnetic recording media. Highlights: • Barium ferrite–silica nanocomposites were prepared by high energy ball milling. • Optimal processing time is 15 h milling and heat treatment at 900 °C. • This is enough to avoid the generation of hematite phase. • Obtain good dispersion of barium ferrite particles in the ceramic matrix • Above this processing time shows the presence of increased amount of hematite

Synthesis of Mn{sub x}Ga{sub 1−x}Fe{sub 2}O{sub 4} magnetic nanoparticles by thermal decomposition method for medical diagnosis applications

Energy Technology Data Exchange (ETDEWEB)

Sánchez, Javier, E-mail: h_javiersanchez@hotmail.com [CINVESTAV-IPN, Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial Saltillo – Ramos Arizpe, Ramos Arizpe, Coahuila CP 25900, México (Mexico); Cortés-Hernández, Dora Alicia; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Reyes-Rodríguez, Pamela Yajaira; Jasso-Terán, Rosario Argentina [CINVESTAV-IPN, Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial Saltillo – Ramos Arizpe, Ramos Arizpe, Coahuila CP 25900, México (Mexico); Bartolo-Pérez, Pascual [CINVESTAV-IPN, Unidad Mérida, Departamento de Física Aplicada, A. P. 73 Cordemex, 97310 Mérida, Yuc., México (Mexico); De-León-Prado, Laura Elena [CINVESTAV-IPN, Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial Saltillo – Ramos Arizpe, Ramos Arizpe, Coahuila CP 25900, México (Mexico)

2017-04-01

In this work, the synthesis of Mn{sub x}Ga{sub 1−x}Fe{sub 2}O{sub 4} (x=0–1) nanosized particles by thermal decomposition method, using tetraethylene glycol (TEG) as a reaction medium, has been performed. The crystalline structure of the inverse spinel obtained in all the cases was identified by X-ray diffraction (XRD). Vibration sample magnetometry (VSM) was used to evaluate the magnetic properties of ferrites and to demonstrate their superparamagnetic behavior and the increase of magnetization values due to the Mn{sup 2+} ions incorporation into the FeGa{sub 2}O{sub 4} structure. Transmission electron microscopy, energy dispersive spectroscopy (TEM-EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the obtained magnetic nanoparticles (MNPs). These MNPs showed a near spherical morphology, an average particle size of 5.6±1.5 nm and a TEG coating layer on their surface. In all the cases MNPs showed no response when submitted to an alternating magnetic field (AMF, 10.2 kA/m, 354 kHz) using magnetic induction tests. These results suggest that the synthesized nanoparticles can be potential candidates for their use in biomedical areas. - Highlights: • Superparamagnetic NPs of Mn{sub x}Ga{sub 1−x}Fe{sub 2}O{sub 4} were synthesized by thermal decomposition. • Saturation magnetization of MnGaFe{sub 2}O{sub 4} increases as Mn ions are increased. • Nanoparticles have a nanometric size of 5.6 nm and show no heating ability.

Coronal magnetometry

CERN Document Server

Zhang, Jie; Bastian, Timothy

2014-01-01

This volume is a collection of research articles on the subject of the solar corona, and particularly, coronal magnetism. The book was motivated by the Workshop on Coronal Magnetism: Connecting Models to Data and the Corona to the Earth, which was held 21 - 23 May 2012 in Boulder, Colorado, USA. This workshop was attended by approximately 60 researchers. Articles from this meeting are contained in this topical issue, but the topical issue also contains contributions from researchers not present at the workshop. This volume is aimed at researchers and graduate students active in solar physics. Originally published in Solar Physics, Vol. 288, Issue 2, 2013 and Vol. 289, Issue 8, 2014.

Charge ordering in Nd{sub 2/3}Ca{sub 1/3}MnO{sub 3}: ESR and magnetometry study

Energy Technology Data Exchange (ETDEWEB)

Polishchuk, D.M.; Tovstolytkin, A.I. [Institute of Magnetism of NASU, 36b Vernadsky Boulevard, Kyiv 03680 (Ukraine); Fertman, E.L.; Desnenko, V.A.; Kravchyna, O. [B. Verkin Institute for Low Temperature Physics and Engineering of NASU, 47 Lenin Ave., Kharkov 61103 (Ukraine); Khalyavin, D.D. [ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Salak, A.N. [Department of Materials and Ceramic Engineering/CICECO, University of Aveiro, Aveiro 3810-193 (Portugal); Anders, A.G. [V. N. Karazin Kharkiv National University, 4 Svobody sq., Kharkiv 61000 (Ukraine); Feher, A. [Institute of Physics, Faculty of Science, P. J. Šafárik University in Košice, Park Angelinum 9, Košice 04154 (Slovakia)

2016-07-15

The evolution of magnetic and electric properties of the narrow-band manganite Nd{sub 2/3}Ca{sub 1/3}MnO{sub 3} was studied by the electron-spin resonance (ESR), static magnetic field (dc) and resistivity techniques in the temperature range of 100–380 K. It was found that below the charge ordering temperature, T{sub CO}≈212 K, the compound is a mixture of the charge ordered and charge disordered phases in varying proportions depending on the temperature. The exchange phase process, when the amount of the charge ordered phase increases under cooling, while the amount of the charge disordered phase decreases is the most intense between ∼220 K and 180 K. At low temperatures, T<160 K, the charge ordered to the charge disordered phase ratio is about 4:1, which is in excellent agreement with previous neutron diffraction data. Both a sharp decrease of the magnetic susceptibility and a huge resistivity increase are evident of the weakening of ferromagnetic correlations and suppression of the double exchange interaction across the charge ordering due to the localization of the charge carriers. - Highlights: • The electron spin resonance and magnetometry study of Nd{sub 2/3}Ca{sub 1/3}MnO{sub 3} compound has been done. • Phase segregated state of the compound below the charge ordering temperature was revealed. • Charge ordered and charge disordered phases in varying proportions depending on the temperature are coexistent. • The exchange phase process is the most intense between ~220 K and 180 K. • At low temperatures the charge ordered to the charge disordered phase ratio is about 4:1.

Terbium doped SnO2 nanoparticles as white emitters and SnO2:5Tb/Fe3O4 magnetic luminescent nanohybrids for hyperthermia application and biocompatibility with HeLa cancer cells.

Science.gov (United States)

Singh, Laishram Priyobarta; Singh, Ningthoujam Premananda; Srivastava, Sri Krishna

2015-04-14

SnO2:5Tb (SnO2 doped with 5 at% Tb(3+)) nanoparticles were synthesised by a polyol method and their luminescence properties at different annealing temperatures were studied. Characterization of nanomaterials was done by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). XRD studies indicate that the prepared nanoparticles were of tetragonal structures. Upon Tb(3+) ion incorporation into SnO2, Sn(4+) changes to Sn(2+) and, on annealing again at higher temperature, Sn(2+) changes to Sn(4+). The prepared nanoparticles were spherical in shape. Sn-O vibrations were found from the FTIR studies. In photoluminescence studies, the intensity of the emission peaks of Tb(3+) ions increases with the increase of annealing temperature, and emission spectra lie in the region of white emission in the CIE diagram. CCT calculations show that the SnO2:5Tb emission lies in cold white emission. Quantum yields up to 38% can be obtained for 900 °C annealed samples. SnO2:5Tb nanoparticles were well incorporated into the PVA polymer and such a material incorporated into the polymer can be used for display devices. The SnO2:5Tb/Fe3O4 nanohybrid was prepared and investigated for hyperthermia applications at different concentrations of the nanohybrid. This achieves a hyperthermia temperature (42 °C) under an AC magnetic field. The hybrid nanomaterial SnO2:5Tb/Fe3O4 was found to exhibit biocompatibility with HeLa cells (human cervical cancer cells) at concentrations up to 74% for 100 μg L(-1). Also, this nanohybrid shows green emission and thus it will be helpful in tracing magnetic nanoparticles through optical imaging in vivo and in vitro application.

High temperature magnetic properties of Co(FeY){sub 2}O{sub 4} synthesized by combustion reaction

Energy Technology Data Exchange (ETDEWEB)

Alves, Thiago Eduardo Pereira, E-mail: thiago.ifgo@gmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia de Goias (IFGO), Goiania (Brazil); Franco Junior, Adolfo [Universidade Federal de Goias (UFG), Goiania (Brazil)

2016-07-01

Full text: Cobalt ferrite is widely studied due to its interesting magnetic behavior at room temperature. However, many technical applications require temperatures that are above that. Thus, it is necessary to understand how some magnetic properties, such as saturation magnetization (Ms), remanent magnetization (Mr), and coercivity (Hc), may behave at high temperatures [1]. Among several methods to synthesize cobalt ferrites, combustion reaction method is intensively used because it is inexpensive, fast and has good control on the stoichiometry. This method is based on the chemistry of propellants and explosives [2]. Therefore, we have prepared a series of nanoparticles of CoFe{sub (2-x)}Y{sub x}O{sub 4}, with x ranging from 0.00 to 0.04, by combustion reaction method. The crystal structure and morphology were characterized by X-ray diffraction (XRD) using Rietveld refinement and transmission electron microscopy (TEM), respectively. Nanocrystalline particles structures in the typical phase of spinel were observed on diffractograms. Micrographies showed high crystalline powders for the particles and particles size within nanoscale range. The magnetic properties were measured by vibrating sample magnetometry (VSM) in broad range of temperature (300-850K). Saturation magnetization (Ms) decreases with Y doping increase, while Hc increases, being about 1.8 higher than the undoped sample. Furthermore, Curie temperature increases with Y doping increase. These magnetic properties were discussed in terms of the particle interactions induced by the thermal fluctuations, cation distribution, and ions exchange between yttrium and cobalt atoms in A-B sites in the cubic structure [3]. References: [1] A. Franco, Jr. and F. C. e Silva, Applied Physics Letters 96, 172505, (2010). 525 [2] S.R. Jain, et al, Combustion and flame 40, 71-79, (1981). [3] A. Franco Jr. et al. Journal of Alloys and Compounds 680, 198-205, (2016). (author)

Mössbauer and magnetization studies of nanosize chromium ferrite ...

African Journals Online (AJOL)

Nanosize chromium ferrite (CrF) powder samples were synthesized by citrate precursor route in the size range of 6 to 35 nm. The structural and magnetic behaviour of these samples were studied using X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Mössbauer spectroscopic techniques. Synthesized ...

A virtual source model for Monte Carlo simulation of helical tomotherapy.

Science.gov (United States)

Yuan, Jiankui; Rong, Yi; Chen, Quan

2015-01-08

The purpose of this study was to present a Monte Carlo (MC) simulation method based on a virtual source, jaw, and MLC model to calculate dose in patient for helical tomotherapy without the need of calculating phase-space files (PSFs). Current studies on the tomotherapy MC simulation adopt a full MC model, which includes extensive modeling of radiation source, primary and secondary jaws, and multileaf collimator (MLC). In the full MC model, PSFs need to be created at different scoring planes to facilitate the patient dose calculations. In the present work, the virtual source model (VSM) we established was based on the gold standard beam data of a tomotherapy unit, which can be exported from the treatment planning station (TPS). The TPS-generated sinograms were extracted from the archived patient XML (eXtensible Markup Language) files. The fluence map for the MC sampling was created by incorporating the percentage leaf open time (LOT) with leaf filter, jaw penumbra, and leaf latency contained from sinogram files. The VSM was validated for various geometry setups and clinical situations involving heterogeneous media and delivery quality assurance (DQA) cases. An agreement of < 1% was obtained between the measured and simulated results for percent depth doses (PDDs) and open beam profiles for all three jaw settings in the VSM commissioning. The accuracy of the VSM leaf filter model was verified in comparing the measured and simulated results for a Picket Fence pattern. An agreement of < 2% was achieved between the presented VSM and a published full MC model for heterogeneous phantoms. For complex clinical head and neck (HN) cases, the VSM-based MC simulation of DQA plans agreed with the film measurement with 98% of planar dose pixels passing on the 2%/2 mm gamma criteria. For patient treatment plans, results showed comparable dose-volume histograms (DVHs) for planning target volumes (PTVs) and organs at risk (OARs). Deviations observed in this study were consistent

Regional-Scale Surface Magnetic Fields and Proton Fluxes to Mercury's Surface from Proton-Reflection Magnetometry

Science.gov (United States)

Winslow, R. M.; Johnson, C. L.; Anderson, B. J.; Gershman, D. J.; Raines, J. M.; Lillis, R. J.; Korth, H.; Slavin, J. A.; Solomon, S. C.; Zurbuchen, T.

2014-12-01

The application of a recently developed proton-reflection magnetometry technique to MESSENGER spacecraft observations at Mercury has yielded two significant findings. First, loss-cone observations directly confirm particle precipitation to Mercury's surface and indicate that solar wind plasma persistently bombards the planet not only in the magnetic cusp regions but over a large fraction of the southern hemisphere. Second, the inferred surface field strengths independently confirm the north-south asymmetry in Mercury's global magnetic field structure first documented from observations of magnetic equator crossings. Here we extend this work with 1.5 additional years of observations (i.e., to 2.5 years in all) to further probe Mercury's surface magnetic field and better resolve proton flux precipitation to the planet's surface. We map regions where proton loss cones are observed; these maps indicate regions where protons precipitate directly onto the surface. The augmentation of our data set over that used in our original study allows us to examine the proton loss cones in cells of dimension 10° latitude by 20° longitude in Mercury body-fixed coordinates. We observe a transition from double-sided to single-sided loss cones in the pitch-angle distributions; this transition marks the boundary between open and closed field lines. At the surface this boundary lies between 60° and 70°N. Our observations allow the estimation of surface magnetic field strengths in the northern cusp region and the calculation of incident proton fluxes to both hemispheres. In the northern cusp, our regional-scale observations are consistent with an offset dipole field and a dipole moment of 190 nT RM3, where RM is Mercury's radius, implying that any regional-scale variations in surface magnetic field strengths are either weak relative to the dipole field or occur at length scales smaller than the resolution of our observations (~300 km). From the global proton flux map (north of 40° S

Magnetometry and transport studies of 2D systems

Energy Technology Data Exchange (ETDEWEB)

Watts, J.P

1999-06-01

This thesis presents measurements of the magnetisation and magnetotransport of two-dimensional electron and hole systems, at low temperatures and high magnetic fields. When the magnetic field is swept through a resistivity minimum associated with the quantum Hall effect, circulating 'eddy' currents are induced in the 2D electron system. These currents may be large enough to cause breakdown of the quantum Hall effect. Breakdown has been examined in high-mobility electron and hole samples, by recording the magnetic moments associated with these eddy currents, and the results have been compared to breakdown models. Eddy currents observed at fractional quantum Hall effect (FQHE) filling factors have been used to determine the FQHE gap energy. The measured value is far closer to theoretical predictions than the results of conventional measurements: this is thought to be because breakdown arises through inter-Landau-level tunnelling, which is local on the scale of the disorder. A series of quantum Hall effect measurements have been performed on a low density sample. Depopulating the Landau levels by applying an increasing gate voltage allowed the numbers of localised and extended states to be counted at each magnetic field. The number of extended states may the be plotted as a function of reducing magnetic field. In certain circumstances, the number of extended states drops to zero before the magnetic field is zero: the system is entirely localised for a range of small fields, consistent with the theories of levitation of extended states. The idea that each Landau level contains only one extended state is also challenged. Measurements of the equilibrium magnetisation of a 2DES may be used to give insight into the shape of the electron density of states. Results are presented of the de Haas - van Alphen oscillations of a very high mobility, low density sample, in which magnetisation oscillations are observed at odd as well as even integer filling factors. The

Paleomagnetic Analysis Using SQUID Microscopy

Science.gov (United States)

Weiss, Benjamin P.; Lima, Eduardo A.; Fong, Luis E.; Baudenbacher, Franz J.

2007-01-01

Superconducting quantum interference device (SQUID) microscopes are a new generation of instruments that map magnetic fields with unprecedented spatial resolution and moment sensitivity. Unlike standard rock magnetometers, SQUID microscopes map magnetic fields rather than measuring magnetic moments such that the sample magnetization pattern must be retrieved from source model fits to the measured field data. In this paper, we presented the first direct comparison between paleomagnetic analyses on natural samples using joint measurements from SQUID microscopy and moment magnetometry. We demonstrated that in combination with apriori geologic and petrographic data, SQUID microscopy can accurately characterize the magnetization of lunar glass spherules and Hawaiian basalt. The bulk moment magnitude and direction of these samples inferred from inversions of SQUID microscopy data match direct measurements on the same samples using moment magnetometry. In addition, these inversions provide unique constraints on the magnetization distribution within the sample. These measurements are among the most sensitive and highest resolution quantitative paleomagnetic studies of natural remanent magnetization to date. We expect that this technique will be able to extend many other standard paleomagnetic techniques to previously inaccessible microscale samples.

Static Voltage Stability Analysis by Using SVM and Neural Network

Directory of Open Access Journals (Sweden)

Mehdi Hajian

2013-01-01

Full Text Available Voltage stability is an important problem in power system networks. In this paper, in terms of static voltage stability, and application of Neural Networks (NN and Supported Vector Machine (SVM for estimating of voltage stability margin (VSM and predicting of voltage collapse has been investigated. This paper considers voltage stability in power system in two parts. The first part calculates static voltage stability margin by Radial Basis Function Neural Network (RBFNN. The advantage of the used method is high accuracy in online detecting the VSM. Whereas the second one, voltage collapse analysis of power system is performed by Probabilistic Neural Network (PNN and SVM. The obtained results in this paper indicate, that time and number of training samples of SVM, are less than NN. In this paper, a new model of training samples for detection system, using the normal distribution load curve at each load feeder, has been used. Voltage stability analysis is estimated by well-know L and VSM indexes. To demonstrate the validity of the proposed methods, IEEE 14 bus grid and the actual network of Yazd Province are used.

Pramana – Journal of Physics | Indian Academy of Sciences

Indian Academy of Sciences (India)

Samples were subjected to vibrating sample magnetometer (VSM) and studies showed that organic additive has altered magnetic properties of these films. The reason for change in magnetic properties and structural characteristics because of the additives were discussed. Mechanical properties such as residual stress, ...

Optimization of spring exchange coupled ferrites, studied by in situ neutron diffraction

DEFF Research Database (Denmark)

Ahlburg, Jakob; Christensen, Mogens; Granados-Miralles, Cecilia

have a spin it will also be possible to measure a magnetic signal and investigate the exchange-coupling. After the reduction the samples was furthermore investigated using powder x-ray diffraction and VSM (vibrating sample magnetometer). To understand the reaction mechanism, a series of experiments...

A single-source photon source model of a linear accelerator for Monte Carlo dose calculation.

Science.gov (United States)

Nwankwo, Obioma; Glatting, Gerhard; Wenz, Frederik; Fleckenstein, Jens

2017-01-01

To introduce a new method of deriving a virtual source model (VSM) of a linear accelerator photon beam from a phase space file (PSF) for Monte Carlo (MC) dose calculation. A PSF of a 6 MV photon beam was generated by simulating the interactions of primary electrons with the relevant geometries of a Synergy linear accelerator (Elekta AB, Stockholm, Sweden) and recording the particles that reach a plane 16 cm downstream the electron source. Probability distribution functions (PDFs) for particle positions and energies were derived from the analysis of the PSF. These PDFs were implemented in the VSM using inverse transform sampling. To model particle directions, the phase space plane was divided into a regular square grid. Each element of the grid corresponds to an area of 1 mm2 in the phase space plane. The average direction cosines, Pearson correlation coefficient (PCC) between photon energies and their direction cosines, as well as the PCC between the direction cosines were calculated for each grid element. Weighted polynomial surfaces were then fitted to these 2D data. The weights are used to correct for heteroscedasticity across the phase space bins. The directions of the particles created by the VSM were calculated from these fitted functions. The VSM was validated against the PSF by comparing the doses calculated by the two methods for different square field sizes. The comparisons were performed with profile and gamma analyses. The doses calculated with the PSF and VSM agree to within 3% /1 mm (>95% pixel pass rate) for the evaluated fields. A new method of deriving a virtual photon source model of a linear accelerator from a PSF file for MC dose calculation was developed. Validation results show that the doses calculated with the VSM and the PSF agree to within 3% /1 mm.

A single-source photon source model of a linear accelerator for Monte Carlo dose calculation.

Directory of Open Access Journals (Sweden)

Obioma Nwankwo

Full Text Available To introduce a new method of deriving a virtual source model (VSM of a linear accelerator photon beam from a phase space file (PSF for Monte Carlo (MC dose calculation.A PSF of a 6 MV photon beam was generated by simulating the interactions of primary electrons with the relevant geometries of a Synergy linear accelerator (Elekta AB, Stockholm, Sweden and recording the particles that reach a plane 16 cm downstream the electron source. Probability distribution functions (PDFs for particle positions and energies were derived from the analysis of the PSF. These PDFs were implemented in the VSM using inverse transform sampling. To model particle directions, the phase space plane was divided into a regular square grid. Each element of the grid corresponds to an area of 1 mm2 in the phase space plane. The average direction cosines, Pearson correlation coefficient (PCC between photon energies and their direction cosines, as well as the PCC between the direction cosines were calculated for each grid element. Weighted polynomial surfaces were then fitted to these 2D data. The weights are used to correct for heteroscedasticity across the phase space bins. The directions of the particles created by the VSM were calculated from these fitted functions. The VSM was validated against the PSF by comparing the doses calculated by the two methods for different square field sizes. The comparisons were performed with profile and gamma analyses.The doses calculated with the PSF and VSM agree to within 3% /1 mm (>95% pixel pass rate for the evaluated fields.A new method of deriving a virtual photon source model of a linear accelerator from a PSF file for MC dose calculation was developed. Validation results show that the doses calculated with the VSM and the PSF agree to within 3% /1 mm.

Physical properties of antiferromagnetic Mn doped ZnO samples: Role of impurity phase

Science.gov (United States)

Neogi, S. K.; Karmakar, R.; Misra, A. K.; Banerjee, A.; Das, D.; Bandyopadhyay, S.

2013-11-01

Structural, morphological, optical, and magnetic properties of nanocrystalline Zn1-xMnxO samples (x=0.01, 0.02, 0.04, 0.06, 0.08 and 0.10) prepared by the sol-gel route are studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV-visible absorption spectroscopy, Superconducting quantum interference device (SQUID) magnetometry and positron annihilation lifetime spectroscopy (PALS). XRD confirms formation of wurzite structure in all the Mn-substituted samples. A systematic increase in lattice constants and decrease in grain size have been observed with increase in manganese doping concentration up to 6 at% in the ZnO structure. An impurity phase (ZnMnO3) has been detected when percentage of Mn concentration is 6 at% or higher. The optical band gap of the Mn-substituted ZnO samples decrease with increase in doping concentration of manganese whereas the width of the localized states increases. The antiferromagnetic exchange interaction is strong in the samples for 2 and 4 at% of Mn doping but it reduces when the doping level increases from 6 at% and further. Positron life time components τ1 and τ2 are found to decrease when concentration of the dopant exceeds 6 at%. The changes in magnetic properties as well as positron annihilation parameters at higher manganese concentration have been assigned as due to the formation of impurity phase. Single phase structure has been observed up to 6 at% of Mn doping. Impurity phase has been developed above 6 at% of Mn doping. Antiferromagnetic and paramagnetic interactions are present in the samples. Defect parameters show sharp fall as Mn concentration above 6 at%. The magnetic and defect properties are modified by the formation of impurity phase.

Physical properties of antiferromagnetic Mn doped ZnO samples: Role of impurity phase

International Nuclear Information System (INIS)

Neogi, S.K.; Karmakar, R.; Misra, A.K.; Banerjee, A.; Das, D.; Bandyopadhyay, S.

2013-01-01

Structural, morphological, optical, and magnetic properties of nanocrystalline Zn 1−x Mn x O samples (x=0.01, 0.02, 0.04, 0.06, 0.08 and 0.10) prepared by the sol–gel route are studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV–visible absorption spectroscopy, Superconducting quantum interference device (SQUID) magnetometry and positron annihilation lifetime spectroscopy (PALS). XRD confirms formation of wurzite structure in all the Mn-substituted samples. A systematic increase in lattice constants and decrease in grain size have been observed with increase in manganese doping concentration up to 6 at% in the ZnO structure. An impurity phase (ZnMnO 3 ) has been detected when percentage of Mn concentration is 6 at% or higher. The optical band gap of the Mn-substituted ZnO samples decrease with increase in doping concentration of manganese whereas the width of the localized states increases. The antiferromagnetic exchange interaction is strong in the samples for 2 and 4 at% of Mn doping but it reduces when the doping level increases from 6 at% and further. Positron life time components τ 1 and τ 2 are found to decrease when concentration of the dopant exceeds 6 at%. The changes in magnetic properties as well as positron annihilation parameters at higher manganese concentration have been assigned as due to the formation of impurity phase. - highlights: • Single phase structure has been observed up to 6 at% of Mn doping. • Impurity phase has been developed above 6 at% of Mn doping. • Antiferromagnetic and paramagnetic interactions are present in the samples. • Defect parameters show sharp fall as Mn concentration above 6 at%. • The magnetic and defect properties are modified by the formation of impurity phase

Physical properties of antiferromagnetic Mn doped ZnO samples: Role of impurity phase

Energy Technology Data Exchange (ETDEWEB)

Neogi, S.K.; Karmakar, R. [Department of Physics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009 (India); Misra, A.K. [UGC DAE Consortium for Scientific Research, Salt Lake, Kolkata 700064 (India); Banerjee, A. [Department of Physics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009 (India); CRNN, University of Calcutta, JD 2, Sector III, Salt Lake, Kolkata 700098 (India); Das, D. [UGC DAE Consortium for Scientific Research, Salt Lake, Kolkata 700064 (India); Bandyopadhyay, S., E-mail: sbaphy@caluniv.ac.in [Department of Physics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009 (India); CRNN, University of Calcutta, JD 2, Sector III, Salt Lake, Kolkata 700098 (India)

2013-11-15

Structural, morphological, optical, and magnetic properties of nanocrystalline Zn{sub 1−x}Mn{sub x}O samples (x=0.01, 0.02, 0.04, 0.06, 0.08 and 0.10) prepared by the sol–gel route are studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV–visible absorption spectroscopy, Superconducting quantum interference device (SQUID) magnetometry and positron annihilation lifetime spectroscopy (PALS). XRD confirms formation of wurzite structure in all the Mn-substituted samples. A systematic increase in lattice constants and decrease in grain size have been observed with increase in manganese doping concentration up to 6 at% in the ZnO structure. An impurity phase (ZnMnO{sub 3}) has been detected when percentage of Mn concentration is 6 at% or higher. The optical band gap of the Mn-substituted ZnO samples decrease with increase in doping concentration of manganese whereas the width of the localized states increases. The antiferromagnetic exchange interaction is strong in the samples for 2 and 4 at% of Mn doping but it reduces when the doping level increases from 6 at% and further. Positron life time components τ{sub 1} and τ{sub 2} are found to decrease when concentration of the dopant exceeds 6 at%. The changes in magnetic properties as well as positron annihilation parameters at higher manganese concentration have been assigned as due to the formation of impurity phase. - highlights: • Single phase structure has been observed up to 6 at% of Mn doping. • Impurity phase has been developed above 6 at% of Mn doping. • Antiferromagnetic and paramagnetic interactions are present in the samples. • Defect parameters show sharp fall as Mn concentration above 6 at%. • The magnetic and defect properties are modified by the formation of impurity phase.

Sodium Carboxymethyl Cellulose Using Acrylamide and Acrylic Acid and Investigation of Drug Delivery Properties

Directory of Open Access Journals (Sweden)

Mahdi Geramipour

2016-07-01

Full Text Available Hydrogels are three-dimensional polymer networks that can absorb and retain a huge amount of aqueous fluids even under certain pressure, but do not dissolve in water. They are responsive to environmental stimulants such as pH and ionic strength of the solution. In this study, a series of novel sodium carboxymethyl cellulose-based hydrogel nanocomposites were synthesized using acrylamide comonomer in the presence of iron magnetic as crosslinker and acrylic acid ammonium persulfate (APS comonomer as initiator. All reaction variables affecting the water absorbency of the hydrogel nanocomposite including the concentration of crosslinking agent and initiator, and comonomers ratio were optimized in order to achieve the maximum absorption capacity. The experimental data showed that the hydrogel nanocomposite exhibited improved swelling capacity compared to the nanoparticel-free hydrogel. In addition, optimized hydrogel nanocomposite showed a good water uptake ability and the equilibrium swelling capacity was achieved within the initial 10 min. In examining the quality of the synthesized hydrogel nanocomposite, the amount of absorption in saline solutions of different concentrations was measured. Furthermore, the swelling behavior of hydrogel nanocomposite in solutions with different pH values was evaluated. The chemical structure of the hydrogel nanocomposites was characterized by means of transmission electron microscopy (TEM, scanning electron microscopy (SEM, vibrating sample magnetometry (VSM, thermogravimetry analysis (TGA, derivative thermogravimetry (DTG and Fourier transform infrared spectroscopy (FTIR. In order to study the drug delivery and drug release behavior, the release of sodium diclofenac as a model drug from synthesized hydrogel nanocomposite was examined in two acidic and basic buffer environments. The results indicated that this hydrogel nanocomposite may be an appropriate alternative for drug release processes in human body.

Electromagnetic interference shielding and microwave absorption properties of cobalt ferrite CoFe2O4/polyaniline composite

Science.gov (United States)

Ismail, Mukhils M.; Rafeeq, Sewench N.; Sulaiman, Jameel M. A.; Mandal, Avinandan

2018-05-01

Improvement of microwave-absorbing materials (MAMs) is the most important research area in various applications, such as in communication, radiation medical exposure, electronic warfare, air defense, and different civilian applications. Conducting polymer, polyaniline doped with para toluene sulphonic acid (PANI-PTSA) as well as cobalt ferrite (CoFe2O4) is synthesized by sol-gel method and intensely blends in different ratios. The characterization of the composite materials, CoFe2O4/PANI-PTSA (CFP1, CFP2, CFP3 and CFP4), was performed by X-ray diffraction (XRD), atomic force microscopy (AFM) and vibrating sample magnetometry (VSM). The microwave-absorbing properties' reflection loss (dB) and important parameters, such as complex relative permittivity ( ɛ r '- jɛ r ″) and complex relative permeability ( µ r '- jµ r ″) were measured in different microwave frequencies in the X-band (8.2-12.4 GHz) region. The composite material CFP3 showed a wider absorption frequency range and maximum reflection loss of - 28.4 dB (99.8% power absorption) at 8.1 GHz and - 9.6 dB (> 90% power absorption) at 11.2 GHz, and so the composite can be used as a microwave absorber; however, it can be more suitable for application in daily life for making cell phones above 9 GHz. Also the results showed that the thicker composites like CFP3 (4 mm) exhibit obviously better EMI SE as compared with the thinner ones (0.19, 0.19, 0.3 mm); this may be related to the low transmission of the EM wave from the composites.

Effect of surfactant amount on the morphology and magnetic properties of monodisperse ZnFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zhao, Haitao, E-mail: zht95711lunwen@163.com; Liu, Ruiping; Zhang, Qiang; Wang, Qiao

2016-03-15

Graphical abstract: Polyol process to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles. - Highlights: • An one-step, facile and inexpensive synthetic route to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles is described. • The sodium citrate stabilized ZnFe{sub 2}O{sub 4} nanoparticles with a diameter in the 5–8 nm size range can be easily dispersed in water. • The synthesis is very robust in terms of variations of experimental parameters. • ZnFe{sub 2}O{sub 4} nanoparticles present ferrimagnetic behavior at room temperature with a small hysteresis. - Abstract: The spinel ZnFe{sub 2}O{sub 4} ferrites with sodium citrate as a surfactant were fabricated by polyol process. The effect of surfactant amount on the structure, morphology and magnetic properties of ZnFe{sub 2}O{sub 4} ferrites were investigated by X-ray diffraction(XRD), transmission electron microscope (TEM), thermogravimetric and differential scanning calorimetry (TG–DSC) and vibrating sample magnetometry (VSM), respectively. The results indicate that the structure of ZnFe{sub 2}O{sub 4} ferrites is a pure cubic spinel structure with a particle size of 5–8 nm. The dispersion of the synthesized ZnFe{sub 2}O{sub 4} is enhanced when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases. The synthesized particles present ferrimagnetic behavior with a small hysteresis at room temperature. The increase of surfactant amount conversely leads to the decrease in the saturation magnetization value (Ms) especially when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases to 8:3. Its Ms value is drastically reduced to 18.97 emu/g.

Fe{sub 3}O{sub 4}@Nico-Ag magnetically recyclable nanocatalyst for azo dyes reduction

Energy Technology Data Exchange (ETDEWEB)

Kurtan, U., E-mail: ukurtan@fatih.edu.tr; Amir, Md.; Baykal, A.

2016-02-15

Graphical abstract: - Highlights: • Fe{sub 3}O{sub 4}@Nico@Ag magnetic recyclable nanocatalyst (MRC) is more effective for the reduction of azo dyes consisting of MB and MO. • It could be reused several times without significant loss in catalytic activity. • Fe{sub 3}O{sub 4}@Nico@Ag (MRCs) has been successively used for colour reduction of MO, MB, EY, RhB and their mixtures. - Abstract: In this study, we report the successful synthesis of Fe{sub 3}O{sub 4}@Nico-Ag nanocomposite as magnetically recyclable nanocatalyst (MRCs) via reflux process at 80 °C for 5 h followed by reduction of Ag{sup +}. FeCl{sub 3}·6H{sub 2}O, FeCl{sub 2}·4H{sub 2}O, AgNO{sub 3} as starting reactants and nicotinic acid as linker. The structure, morphology, thermal behaviour and magnetic properties of the product were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDX), thermal gravimetry (TG) and vibrating sample magnetometry (VSM), respectively. The catalytic activity of product for various azo dyes such as methylene blue (MB), methyl orange (MO), Rhodamine B (RhB) and eosin Y (EY) and their double mixtures were studied. It was found that Fe{sub 3}O{sub 4}@Nico-Ag MRCs is an efficient catalyst and can also rapidly separated from the reaction medium using magnet without considerable loss in its catalytic activity and used several times. Fe{sub 3}O{sub 4}@Nico-Ag MRCs has potential for the treatment of industrial dye pollutants.

Thermally activated formation of martensite in Fe-C alloys and Fe-17%Cr-C stainless steels during heating from boiling nitrogen temperature

DEFF Research Database (Denmark)

Villa, Matteo; Hansen, Mikkel Fougt; Somers, Marcel A. J.

2016-01-01

The thermally activated austenite-to-martensite transformation was investigated by magnetometry in three Fe-C alloys and in two 17%Cr stainless steels. After quenching to room temperature, samples were immersed in boiling nitrogen and martensite formation was followed during subsequent (re......)heating to room temperature. Different tests were performed applying heating rates from 0.5 K/min to 10 K/min. An additional test consisted in fast (re)heating the samples by immersion in water. Thermally activated martensite formation was demonstrated for all investigated materials by a heating rate......-dependent transformation curve. Moreover, magnetometry showed that the heating rate had an influence on the fraction of martensite formed during sub-zero Celsius treatment. The activation energy for thermally activated martensite formation was quantified in the range 11‒21 kJ/mol by a Kissinger-like method....

Some aspects of nanocrystalline nickel and zinc ferrites processed using microemulsion technique

NARCIS (Netherlands)

Misra, RDK; Kale, A; Kooi, BJ; De Hosson, JTM

2003-01-01

Nanocrystalline nickel and zinc ferrites synthesised using a microemulsion technique were characterised by high resolution transmission electron microscopy and vibrating sample magnetometry. A narrow and uniform distribution of crystals of size range 5-8 nm, distinguished by a clear lack of

Magnetic iron oxide nanoparticles grafted N-isopropylacrylamide/chitosan copolymer for the extraction and determination of letrozole in human biological samples.

Science.gov (United States)

Khalaj Moazen, Mercede; Ahmad Panahi, Homayon

2017-03-01

Magnetic iron oxide nanoparticles are used for the extraction of a drug from an aqueous solution. In the current study, the magnetic iron oxide nanoparticles were synthesized via a facile coprecipitation approach, and then modified by (3-mercaptopropyl)trimethoxysilane followed by grafting thermosensitive polymer N-isopropylacrylamide and biopolymer chitosan. Structure, morphology, size, thermal resistance, specific surface area, and magnetic properties of the grafted nanosorbent were characterized by using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, elemental analysis, thermogravimetric analysis, specific surface area analysis and vibrating sample magnetometry. The effective parameters on sorption/desorption of letrozole on grafted magnetic nanosorbent were evaluated. The best sorption of letrozole via the grafted nanosorbent occurred at 20°C at an optimum pH of 7. The extraction of trace letrozole in human biological fluids is investigated and revealed 89.1 and 97.8% recovery in plasma and urine, respectively. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Volatile substance misuse deaths in Washington State, 2003-2012.

Science.gov (United States)

Ossiander, Eric M

2015-01-01

Volatile substance misuse (VSM - also known as huffing or sniffing) causes some deaths, but because there are no specific cause-of-death codes for VSM, these deaths are rarely tabulated. Count and describe VSM deaths occurring in Washington State during 2003-2012. We used the textual cause-of-death information on death certificates to count VSM-associated deaths that occurred in Washington State during 2003-2012. We extracted records that contained words suggesting either a method of inhalation or a substance commonly used for VSM, and reviewed those records to identify deaths on which the inhalation of a volatile substance was mentioned. We conducted a descriptive analysis of those deaths. Fifty-six deaths involving VSM occurred in Washington State during 2003-2012. VSM deaths occurred primarily among adults age 20 and over (91%), males (88%), and whites (93%). Twelve different chemicals were associated with deaths, but 1 of them, difluoroethane, was named on 30 death certificates (54%), and its involvement increased during the study period. Gas duster products were named as the source of difluoroethane for 12 deaths; no source was named for the other 18 difluoroethane deaths. Most VSM deaths occurred among white male adults, and gas duster products containing difluoroethane were the primary source of inhalants. Approaches to deter VSM, such as the addition of bitterants to gas dusters, should be explored.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

The heterogeneous nanocatalyst was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), atomic absorption spectroscopy (AAS), vibrating sample magnetometer (VSM) and nitrogen adsorption–desorption isotherm ...

Magnetic anisotropy of Ni/Cr multilayers

International Nuclear Information System (INIS)

Kang, S.; Xia, H.

1997-01-01

The magnetic anisotropy of Ni/Cr multilayers has been investigated by using vibrating sample magnetometer (VSM) and ferromagnetic resonance techniques (FMR). The FMR spectra are obtained as a function of the orientation of the applied magnetic field from in-plane to out-of-plane. The results are fitted theoretically to determine the magnetic anisotropy. From VSM and FMR, a positive value for Ni/Cr interface anisotropy is obtained, which favours a perpendicular easy axis. The possible mechanism for the perpendicular anisotropy has been discussed and it may be attributed to the magnetostriction, caused by intrinsic stress due to lattice mismatch. (orig.). With 005 figs., 001 tabs

Structural, chemical and magnetic properties of secondary phases in Co-doped ZnO

DEFF Research Database (Denmark)

Ney, A; Kovács, András; Ney, V

2011-01-01

, chemical and magnetic properties of Co-doped ZnO samples. It can be established on a quantitative basis that the superparamagnetic (SPM) behavior observed by integral superconducting quantum interference device magnetometry is not an intrinsic property of the material but stems from precipitations...

Fabrication of all diamond scanning probes for nanoscale magnetometry

OpenAIRE

Appel Patrick; Neu Elke; Ganzhorn Marc; Barfuss Arne; Batzer Marietta; Gratz Micha; Tschoepe Andreas; Maletinsky Patrick

2016-01-01

The electronic spin of the nitrogen vacancy (NV) center in diamond forms an atomically sized, highly sensitive sensor for magnetic fields. To harness the full potential of individual NV centers for sensing with high sensitivity and nanoscale spatial resolution, NV centers have to be incorporated into scanning probe structures enabling controlled scanning in close proximity to the sample surface. Here, we present an optimized procedure to fabricate single-crystal, all-diamond scanning probes s...

Synthesis and characterization of BaNiO3 using a solid-state ...

Indian Academy of Sciences (India)

2017-07-26

Jul 26, 2017 ... In the present study, the preparation of BaNiO3 nano-oxide is reported via simple solid-state thermal decompo- ... Oxides; perovskite; magnetic fluid; XRD; SEM; VSM. 1. .... ray spectroscopy (EDS) using gold-coated samples.

PDZK1 prevents neointima formation via suppression of breakpoint cluster region kinase in vascular smooth muscle.

Directory of Open Access Journals (Sweden)

Wan Ru Lee

Full Text Available Scavenger receptor class B, type I (SR-BI and its adaptor protein PDZK1 mediate responses to HDL cholesterol in endothelium. Whether the receptor-adaptor protein tandem serves functions in other vascular cell types is unknown. The current work determined the roles of SR-BI and PDZK1 in vascular smooth muscle (VSM. To evaluate possible VSM functions of SR-BI and PDZK1 in vivo, neointima formation was assessed 21 days post-ligation in the carotid arteries of wild-type, SR-BI-/- or PDZK1-/- mice. Whereas neointima development was negligible in wild-type and SR-BI-/-, there was marked neointima formation in PDZK1-/- mice. PDZK1 expression was demonstrated in primary mouse VSM cells, and compared to wild-type cells, PDZK1-/- VSM displayed exaggerated proliferation and migration in response to platelet derived growth factor (PDGF. Tandem affinity purification-mass spectrometry revealed that PDZK1 interacts with breakpoint cluster region kinase (Bcr, which contains a C-terminal PDZ binding sequence and is known to enhance responses to PDGF in VSM. PDZK1 interaction with Bcr in VSM was demonstrated by pull-down and by coimmunoprecipitation, and the augmented proliferative response to PDGF in PDZK1-/- VSM was abrogated by Bcr depletion. Furthermore, compared with wild-type Bcr overexpression, the introduction of a Bcr mutant incapable of PDZK1 binding into VSM cells yielded an exaggerated proliferative response to PDGF. Thus, PDZK1 has novel SR-BI-independent function in VSM that affords protection from neointima formation, and this involves PDZK1 suppression of VSM cell proliferation via an inhibitory interaction with Bcr.

Deriving surface soil moisture from reflected GNSS signal observations from a grassland site in southwestern France

Science.gov (United States)

Zhang, Sibo; Calvet, Jean-Christophe; Darrozes, José; Roussel, Nicolas; Frappart, Frédéric; Bouhours, Gilles

2018-03-01

This work assesses the estimation of surface volumetric soil moisture (VSM) using the global navigation satellite system interferometric reflectometry (GNSS-IR) technique. Year-round observations were acquired from a grassland site in southwestern France using an antenna consecutively placed at two contrasting heights above the ground surface (3.3 and 29.4 m). The VSM retrievals are compared with two independent reference datasets: in situ observations of soil moisture, and numerical simulations of soil moisture and vegetation biomass from the ISBA (Interactions between Soil, Biosphere and Atmosphere) land surface model. Scaled VSM estimates can be retrieved throughout the year removing vegetation effects by the separation of growth and senescence periods and by the filtering of the GNSS-IR observations that are most affected by vegetation. Antenna height has no significant impact on the quality of VSM estimates. Comparisons between the VSM GNSS-IR retrievals and the in situ VSM observations at a depth of 5 cm show good agreement (R2 = 0.86 and RMSE = 0.04 m3 m-3). It is shown that the signal is sensitive to the grass litter water content and that this effect triggers differences between VSM retrievals and in situ VSM observations at depths of 1 and 5 cm, especially during light rainfall events.

Carbon coated magnetic nanoparticles as a novel magnetic solid phase extraction adsorbent for simultaneous extraction of methamphetamine and ephedrine from urine samples.

Science.gov (United States)

Taghvimi, Arezou; Hamishehkar, Hamed

2017-01-15

This paper develops a highly selective, specific and efficient method for simultaneous determination of ephedrine and methamphetamine by a new carbon coated magnetic nanoparticles (C/MNPs) as a magnetic solid phase extraction (MSPE) adsorbent in biological urine medium. The characterization of synthesized magnetic nano adsorbent was completely carried out by various characterization techniques like Fourier transform infrared (FT-IR) spectroscopy, powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Nine important parameters influencing extraction efficiency including amount of adsorbent, amounts of sample volume, pH, type and amount of extraction organic solvent, time of extraction and desorption, agitation rate and ionic strength of extraction medium, were studied and optimized. Under optimized extraction conditions, a good linearity was observed in the concentration range of 100-2000ng/mL for ephedrine and 100-2500ng/mL for methamphetamine. Analysis of positive urine samples was carried out by proposed method with the recovery of 98.71 and 97.87% for ephedrine and methamphetamine, respectively. The results indicated that carbon coated magnetic nanoparticles could be applied in clinical and forensic laboratories for simultaneous determination of abused drugs in urine media. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis and characterization of cobalt-manganese oxides

International Nuclear Information System (INIS)

Valencia, J.; Arias, N.P.; Giraldo, O.; Rosales-Rivera, A.

2012-01-01

Cobalt doped/un-doped manganese oxides materials were synthesized at various doping rates by soft chemical reactions, oxidation-reduction method, which allows generating a metal-mixed oxide. The synthesized materials were characterized using several techniques including chemical analysis, X-rays diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The chemical analysis confirmed the presence of cobalt in the samples. XRD patterns reveal mainly a spinel-like structure and SEM micrographs exhibited morphology with fine aggregate of particles. TGA profiles showed weight loss due to loss of water in a first step, followed by a loss of oxygen from the lattice associated with partial reduction of Mn 4+ to Mn 3+ . VSM was used to measure the magnetization as a function of the applied magnetic field at temperatures T=50 and 300 K. Different magnetic behaviors were observed when cobalt percentage changed in the samples. These behaviors are considered to be related to the size of the particles and composition of the materials. Higher coercive field and lesser magnetization were observed for the sample with higher cobalt content.

A comprehensive study of ferromagnetic resonance and structural properties of iron-rich nickel ferrite (Ni{sub x}Fe{sub 3−x}O{sub 4}, x≤1) films grown by chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Pachauri, Neha; Khodadadi, Behrouz [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Singh, Amit V. [Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Mohammadi, Jamileh Beik [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Martens, Richard L. [Central Analytical Facility (CAF), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); LeClair, Patrick R.; Mewes, Claudia; Mewes, Tim [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Gupta, Arunava [Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, Alabama 35487 (United States)

2016-11-01

We report a detailed study of the structural and ferromagnetic resonance properties of spinel nickel ferrite (NFO) films, grown on (100)-oriented cubic MgAl{sub 2}O{sub 4} substrates by direct liquid injection chemical vapor deposition (DLI-CVD) technique. Three different compositions of NFO films (Ni{sub x}Fe{sub 3−x}O{sub 4} where x=1, 0.8, 0.6) deposited at optimized growth temperature of 600 °C are characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometry (VSM), and broadband ferromagnetic resonance (FMR) techniques. XRD confirms the growth of epitaxial, single crystalline Ni{sub x}Fe{sub 3−x}O{sub 4} films. The out-of-plane lattice constant (c) obtained for Ni{sub 0.8}Fe{sub 2.2}O{sub 4} film is slightly higher than the bulk value (0.833 nm), indicating only partial strain relaxation whereas for the other two compositions (x=1 and x=0.6) films exhibit complete relaxation. The in-plane and out-of-plane FMR linewidths measurements at 10 GHz give the lowest values of 458 Oe and 98 Oe, respectively, for Ni{sub 0.8}Fe{sub 2.2}O{sub 4} film as compared to the other two compositions. A comprehensive frequency (5–40 GHz) and temperature (10–300 K) dependent FMR study of the Ni{sub 0.8}Fe{sub 2.2}O{sub 4} sample for both in-lane and out-of-plane configurations reveals two magnon scattering (TMS) as the dominant in-plane relaxation mechanism. It is observed that the TMS contribution to the FMR linewidth scales with the saturation magnetization M{sub s}. In-plane angle-dependent FMR measurements performed on the same sample show that the ferromagnetic resonance field (H{sub res}) and the FMR linewidth (ΔH) have a four-fold symmetry that is consistent with the crystal symmetry of the spinel. SEM measurements show formation of pyramid-like microstructures at the surface of the Ni{sub 0.8}Fe{sub 2.2}O{sub 4} sample, which can explain the observed four-fold symmetry of the FMR linewidth.

Peak effect studies in single crystals CeRu2 and 2H-NbS2

Indian Academy of Sciences (India)

vibrating sample magnetometer (VSM) (Oxford Instruments, UK) on single crystal sam- ples of CeRu2 and 2H-NbS2. All the measurements were carried out by cooling the sample in zero field (ZFC mode) and then by applying the magnetic field. The measurements were carried out with the magnetic field parallel to the cube ...

Deriving surface soil moisture from reflected GNSS signal observations from a grassland site in southwestern France

Directory of Open Access Journals (Sweden)

S. Zhang

2018-03-01

Full Text Available This work assesses the estimation of surface volumetric soil moisture (VSM using the global navigation satellite system interferometric reflectometry (GNSS-IR technique. Year-round observations were acquired from a grassland site in southwestern France using an antenna consecutively placed at two contrasting heights above the ground surface (3.3 and 29.4 m. The VSM retrievals are compared with two independent reference datasets: in situ observations of soil moisture, and numerical simulations of soil moisture and vegetation biomass from the ISBA (Interactions between Soil, Biosphere and Atmosphere land surface model. Scaled VSM estimates can be retrieved throughout the year removing vegetation effects by the separation of growth and senescence periods and by the filtering of the GNSS-IR observations that are most affected by vegetation. Antenna height has no significant impact on the quality of VSM estimates. Comparisons between the VSM GNSS-IR retrievals and the in situ VSM observations at a depth of 5 cm show good agreement (R2 =  0.86 and RMSE  =  0.04 m3 m−3. It is shown that the signal is sensitive to the grass litter water content and that this effect triggers differences between VSM retrievals and in situ VSM observations at depths of 1 and 5 cm, especially during light rainfall events.

Spectroscopic and magnetic studies of highly dispersible superparamagnetic silica coated magnetite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Tadyszak, Krzysztof [NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Institute of Molecular Physics Polish Academy of Sciences, ul. Mariana Smo.luchowskiego 17, 60-179 Poznań (Poland); Kertmen, Ahmet, E-mail: ahmet.kertmen@pg.gda.pl [Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk (Poland); Coy, Emerson [NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Andruszkiewicz, Ryszard; Milewski, Sławomir [Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk (Poland); Kardava, Irakli; Scheibe, Błażej; Jurga, Stefan [NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Chybczyńska, Katarzyna, E-mail: katarzyna.chybczynska@ifmpan.poznan.pl [Institute of Molecular Physics Polish Academy of Sciences, ul. Mariana Smo.luchowskiego 17, 60-179 Poznań (Poland)

2017-07-01

Highlights: • Superparamagnetic core-shell nanoparticles of Fe{sub 2}O{sub 3}@Silica were obtained. • Magnetic response was studied by DC, AC magnetometry and EPR spectroscopy. • Nanoparticles show magnetite structure with a well-defined Verwey transition. • Samples show no inter particle magnetic interactions or agglomeration. - Abstract: Superparamagnetic behavior in aqueously well dispersible magnetite core-shell Fe{sub 3}O{sub 4}@SiO{sub 2} nanoparticles is presented. The magnetic properties of core-shell nanoparticles were measured with use of the DC, AC magnetometry and EPR spectroscopy. Particles where characterized by HR-TEM and Raman spectroscopy, showing a crystalline magnetic core of 11.5 ± 0.12 nm and an amorphous silica shell of 22 ± 1.5 nm in thickness. The DC, AC magnetic measurements confirmed the superparamagnetic nature of nanoparticles, additionally the EPR studies performed at much higher frequency than DC, AC magnetometry (9 GHz) have confirmed the paramagnetic nature of the nanoparticles. Our results show the excellent magnetic behavior of the particles with a clear magnetite structure, which are desirable properties for environmental remediation and biomedical applications.

Strain-induced structural, magnetic and ferroelectric properties of ...

Indian Academy of Sciences (India)

2017-07-25

Jul 25, 2017 ... deposited on the composite film surface by DC sputtering techniques. The magnetic measurements of these composite films were performed using a vibratory sample magnetometer. (VSM). Ferroelectric properties of films were measured using a Precision multiferroic analyser. All measurements were per-.

Applying value stream mapping techniques to eliminate non-value-added waste for the procurement of endovascular stents

International Nuclear Information System (INIS)

Teichgräber, Ulf K.; Bucourt, Maximilian de

2012-01-01

Objectives: To eliminate non-value-adding (NVA) waste for the procurement of endovascular stents in interventional radiology services by applying value stream mapping (VSM). Materials and methods: The Lean manufacturing technique was used to analyze the process of material and information flow currently required to direct endovascular stents from external suppliers to patients. Based on a decision point analysis for the procurement of stents in the hospital, a present state VSM was drawn. After assessment of the current status VSM and progressive elimination of unnecessary NVA waste, a future state VSM was drawn. Results: The current state VSM demonstrated that out of 13 processes for the procurement of stents only 2 processes were value-adding. Out of the NVA processes 5 processes were unnecessary NVA activities, which could be eliminated. The decision point analysis demonstrated that the procurement of stents was mainly a forecast driven push system. The future state VSM applies a pull inventory control system to trigger the movement of a unit after withdrawal by using a consignment stock. Conclusion: VSM is a visualization tool for the supply chain and value stream, based on the Toyota Production System and greatly assists in successfully implementing a Lean system.

Characterization of magnetic material in the mound-building termite Macrotermes gilvus in Southeast Asia

Energy Technology Data Exchange (ETDEWEB)

Esa, Mohammad Faris Mohammad; Hassan, Ibrahim Haji [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor (Malaysia); Rahim, Faszly; Hanifah, Sharina Abu [School of Environmental Scieces and Natural Resources Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor (Malaysia)

2015-09-25

Magnetic material such as magnetite are known as particles that respond to external magnetic field with their ferromagnetic properties as they are believed contribute to in responding to the geomagnetic field. These particles are used by terrestrial animals such as termites for navigation and orientation. Since our earth react as giant magnetic bar, the magnitude of this magnetic field present by intensity and direction (inclination and direction). The magnetic properties and presence of magnetite in termites Macrotermes gilvus, common mound-building termite were tested. M. gilvus termites was tested with a Vibrating Sample Magnetometer VSM to determine the magnetic properties of specimen. The crushed body sample was characterized with X-Ray Diffraction XRD to show the existent of magnetic material (magnetite) in the specimens. Results from VSM indicate that M. gilvus has diamagnetism properties. The characterization by XRD shows the existent of magnetic material in our specimen in low concentration.

Characterization of magnetic material in the mound-building termite Macrotermes gilvus in Southeast Asia

International Nuclear Information System (INIS)

Esa, Mohammad Faris Mohammad; Hassan, Ibrahim Haji; Rahim, Faszly; Hanifah, Sharina Abu

2015-01-01

Magnetic material such as magnetite are known as particles that respond to external magnetic field with their ferromagnetic properties as they are believed contribute to in responding to the geomagnetic field. These particles are used by terrestrial animals such as termites for navigation and orientation. Since our earth react as giant magnetic bar, the magnitude of this magnetic field present by intensity and direction (inclination and direction). The magnetic properties and presence of magnetite in termites Macrotermes gilvus, common mound-building termite were tested. M. gilvus termites was tested with a Vibrating Sample Magnetometer VSM to determine the magnetic properties of specimen. The crushed body sample was characterized with X-Ray Diffraction XRD to show the existent of magnetic material (magnetite) in the specimens. Results from VSM indicate that M. gilvus has diamagnetism properties. The characterization by XRD shows the existent of magnetic material in our specimen in low concentration

Characterization of magnetic material in the mound-building termite Macrotermes gilvus in Southeast Asia

Science.gov (United States)

Esa, Mohammad Faris Mohammad; Rahim, Faszly; Hassan, Ibrahim Haji; Hanifah, Sharina Abu

2015-09-01

Magnetic material such as magnetite are known as particles that respond to external magnetic field with their ferromagnetic properties as they are believed contribute to in responding to the geomagnetic field. These particles are used by terrestrial animals such as termites for navigation and orientation. Since our earth react as giant magnetic bar, the magnitude of this magnetic field present by intensity and direction (inclination and direction). The magnetic properties and presence of magnetite in termites Macrotermes gilvus, common mound-building termite were tested. M. gilvus termites was tested with a Vibrating Sample Magnetometer VSM to determine the magnetic properties of specimen. The crushed body sample was characterized with X-Ray Diffraction XRD to show the existent of magnetic material (magnetite) in the specimens. Results from VSM indicate that M. gilvus has diamagnetism properties. The characterization by XRD shows the existent of magnetic material in our specimen in low concentration.

Preparation and characterization of polymer nanocomposites coated magnetic nanoparticles for drug delivery applications

Energy Technology Data Exchange (ETDEWEB)

Prabha, G., E-mail: gprabhagovinn@gmail.com; Raj, V., E-mail: alaguraj2@rediffmail.com

2016-06-15

In the present research work, the anticancer drug ‘curcumin’ is loaded with Chitosan (CS)-polyethylene glycol (PEG)-polyvinylpyrrolidone (PVP) (CS-PEG-PVP) polymer nanocomposites coated with superparamagnetic iron oxide (Fe{sub 3}O{sub 4}) nanoparticles. The system can be used for targeted and controlled drug delivery of anticancer drugs with reduced side effects and greater efficiency. The prepared nanoparticles were characterized by Fourier transmission infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Curcumin drug loaded Fe{sub 3}O{sub 4}-CS, Fe{sub 3}O{sub 4}-CS-PEG and Fe{sub 3}O{sub 4}-CS-PEG-PVP nanoparticles exhibited the mean particle size in the range of 183–390 nm with a zeta potential value of 26–41 mV as measured using Malvern Zetasizer. The encapsulation efficiency, loading capacity and in-vitro drug release behavior of curcumin drug loaded Fe{sub 3}O{sub 4}-CS, Fe{sub 3}O{sub 4}-CS-PEG and Fe{sub 3}O{sub 4}-CS-PEG-PVP nanoparticles were studied using UV spectrophotometer. Besides, the cytotoxicity of the prepared nanoparticles using MTT assay was also studied. The curcumin drug release was examined at different pH medium and it was proved that the drug release depends upon the pH medium in addition to the nature of matrix. - Highlights: • The considered drug carrier Fe{sub 3}O{sub 4}-CS-PEG-PVP nanoparticles were prepared and entrapping (Curcumin). • The amount of the drug had great effect on the drug LC and EE and zeta potential Nanocomposites. • The Curcumin- loaded Fe{sub 3}O{sub 4}-CS, Fe{sub 3}O{sub 4}-CS-PEG and Fe{sub 3}O{sub 4}-CS-PEG-PVP nanocomposites showed pH responsive drug release.

Preparation and characterization of polymer nanocomposites coated magnetic nanoparticles for drug delivery applications

International Nuclear Information System (INIS)

Prabha, G.; Raj, V.

2016-01-01

In the present research work, the anticancer drug ‘curcumin’ is loaded with Chitosan (CS)-polyethylene glycol (PEG)-polyvinylpyrrolidone (PVP) (CS-PEG-PVP) polymer nanocomposites coated with superparamagnetic iron oxide (Fe 3 O 4 ) nanoparticles. The system can be used for targeted and controlled drug delivery of anticancer drugs with reduced side effects and greater efficiency. The prepared nanoparticles were characterized by Fourier transmission infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Curcumin drug loaded Fe 3 O 4 -CS, Fe 3 O 4 -CS-PEG and Fe 3 O 4 -CS-PEG-PVP nanoparticles exhibited the mean particle size in the range of 183–390 nm with a zeta potential value of 26–41 mV as measured using Malvern Zetasizer. The encapsulation efficiency, loading capacity and in-vitro drug release behavior of curcumin drug loaded Fe 3 O 4 -CS, Fe 3 O 4 -CS-PEG and Fe 3 O 4 -CS-PEG-PVP nanoparticles were studied using UV spectrophotometer. Besides, the cytotoxicity of the prepared nanoparticles using MTT assay was also studied. The curcumin drug release was examined at different pH medium and it was proved that the drug release depends upon the pH medium in addition to the nature of matrix. - Highlights: • The considered drug carrier Fe 3 O 4 -CS-PEG-PVP nanoparticles were prepared and entrapping (Curcumin). • The amount of the drug had great effect on the drug LC and EE and zeta potential Nanocomposites. • The Curcumin- loaded Fe 3 O 4 -CS, Fe 3 O 4 -CS-PEG and Fe 3 O 4 -CS-PEG-PVP nanocomposites showed pH responsive drug release.

Superparamagnetic graphene oxide-based dispersive-solid phase extraction for preconcentration and determination of tamsulosin hydrochloride in human plasma by high performance liquid chromatography-ultraviolet detection.

Science.gov (United States)

Pashaei, Yaser; Ghorbani-Bidkorbeh, Fatemeh; Shekarchi, Maryam

2017-05-26

In the present study, superparamagnetic graphene oxide-Fe 3 O 4 nanocomposites were successfully prepared by a modified impregnation method (MGO mi ) and their application as a sorbent in the magnetic-dispersive solid phase extraction (M-dSPE) mode to the preconcentration and determination of tamsulosin hydrochloride (TMS) in human plasma was investigated by coupling with high performance liquid chromatography-ultraviolet detection (HPLC-UV). The structure, morphology and magnetic properties of the prepared nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). Some factors affecting the extraction efficiency, including the pH value, amount of sorbent, extraction time, elution solvent and its volume, and desorption time were studied and optimized. Magnetic nanocomposites plasma extraction of TMS following HPLC analyses showed a linear calibration curve in the range of 0.5-50.0ngmL -1 with an acceptable correlation coefficient (R 2 =0.9988). The method was sensitive, with a low limit of detection (0.17ngmL -1 ) and quantification (0.48ngmL -1 ). Inter- and intra-day precision expressed as relative standard deviation (n=3) and the preconcentration factor, were found to be 5.6-7.2%, 2.9-4.2% and 10, respectively. Good recoveries (98.1-101.4%) with low relative standard deviations (4.2-5.0%) indicated that the matrices under consideration do not significantly affect the extraction process. Due to its high precision and accuracy, the developed method may be a HPLC-UV alternative with M-dSPE for bioequivalence analysis of TMS in human plasma. Copyright © 2017 Elsevier B.V. All rights reserved.

Structural and Morphological Properties of Zn{sub 1−x}Zr{sub x}O with Room-Temperature Ferromagnetism and Fabricated by Using the Co-Precipitation Technique

Energy Technology Data Exchange (ETDEWEB)

Hassan, M.; Irfan, R.; Riaz, S.; Naseem, S.; Hussain, S. S. [University of the Punjab, Lahore (Pakistan); Murtaza, G. [Government College University, Lahore (Pakistan)

2017-03-15

In this study, ZnO was doped with various concentrations of zirconium (x{sub Zr} = 0 - 5 mole%), by using the co-precipitation method so as to achieve successful formation of a single-phase diluted magnetic semiconductor. X-Ray diffraction results showed that the crystal structure of Zn{sub 1−x}Zr{sub x}O was that of hexagonal wurtzite. The structural properties showed no additional phases at low impurity contents (x{sub Zr} < 3%); however, impurity peaks belonging to ZrO{sub 2} appeared at high impurity contents (x{sub Zr} ≥ 3%). The calculated ZnO lattice constants 'a' and 'c' were found to be 3.256 Å and 5.203 Å, respectively, which are in close match to the values found in the literature. For undoped ZnO, the average calculated particle size was 75.35 nm, and calculated bond length was 1.98 Å. The residual strains and the secondary phases of ZrO{sub 2} were found to affect the lattice parameters and the bond lengths. The scanning electron microscopy images showed a porous structure with non-uniform surface morphology. However, a few nano-scale dendrite-type structures were also present, indicating the potential applications of Zr-doped ZnO in nano-devices. Vibrating sample magnetometry (VSM) was employed to measure the magnetic properties, and the measurements showed undoped ZnO to be diamagnetic; however, doping with Zr induced a small ferromagnetic character at small magnetic fields. On the other hand, a paramagnetic behavior was evident at higher magnetic fields. The magnetization at 1T was observed to degrade with increasing Zr content in the ZnO host lattice, which was due to the residual strains and the secondary phases.

Managing Viable Knowledge

NARCIS (Netherlands)

Achterbergh, J.M.I.M.; Vriens, D.J.

2002-01-01

In this paper, Beer's Viable System Model (VSM) is applied to knowledge management. Based on the VSM, domains of knowledge are identified that an organization should possess to maintain its viability. The logic of the VSM is also used to support the diagnosis, design and implementation of the

Should the mass of a nanoferrite sample prepared by autocombustion method be considered as a realistic preparation parameter?

Energy Technology Data Exchange (ETDEWEB)

Wahba, Adel Maher, E-mail: adel.mousa@f-eng.tanta.edu.eg [Department of Engineering Physics and Mathematics, Faculty of Engineering, Tanta University (Egypt); Mohamed, Mohamed Bakr [Ain shams University, Faculty of Science, Physics Department, Cairo (Egypt)

2017-02-15

Detectable variations in structural, elastic and magnetic properties have been reported depending on the mass of the cobalt nanoferrite sample prepared by citrate autocombustion method. Heat released during the autocombustion process and its duration are directly proportional to the mass to be prepared, and is thus expected to affect both the crystallite size and the cation distribution giving rise to the reported variations in microstrain, magnetization, and coercivity. Formation of a pure spinel phase has been validated using X-ray diffraction patterns (XRD) and Fourier-transform infrared (FTIR) spectra. Crystallite sizes obtained from Williamson-Hall (W-H) method range from 28–87 nm, being further supported by images of high-resolution transmission electron microscope (HRTEM). Saturation magnetization and coercivity deduced from M-H hysteresis loops show a clear correlation with the cation distribution, which was proposed on the basis of experimentally obtained data of XRD, VSM, and IR. Elastic parameters have been estimated using the cation distribution and FTIR data, with a resulting trend quite opposite to that of the lattice parameter. - Highlights: • Samples with different masses of CoFe{sub 2}O{sub 4} were prepared by autocombustion method. • XRD and IR data confirmed a pure spinel cubic structure for all samples. • Structural and magnetic properties show detectable changes with the mass prepared. • Cation distribution was suggested from experimental data of XRD, IR, and M-H loops.

Structural and magnetic studies on copper succinate dihydrate

Indian Academy of Sciences (India)

The four bis-bidendate succinate anions form syn–syn bridges among two copper atomsto form a polymeric two-dimensional chain. From room temperature vibrating sample magnetometer (VSM) studies themagnetic moment of the material is calculated as 1.35 Bohr magneton (BM), indicating antiferromagnetic interaction ...

Pramana – Journal of Physics | Indian Academy of Sciences

Indian Academy of Sciences (India)

... ranging from 30 to 100 nm. The applied potential and the duration of each potential square pulse determine the thickness of the metal layers. The nanowires have been characterized by transmission electron microscopy (TEM), magnetic force microscopy (MFM), and vibrating sample magnetometer (VSM) measurements.

Effect of iron content on permeability and power loss characteristics of

Indian Academy of Sciences (India)

Magnetic properties like saturation magnetization, coercivity, retentivity have been measured by vibrating sample magnetometer (VSM). The permeability of cadmium doped lithium ferrites exhibited higher values than zinc doped lithium ferrites. The power loss of cadmium doped lithium ferrites is lesser as compared to zinc ...

Lean as a Tool for Systematic Employee based Improvement of Psychosocial Factors in Hospitals

DEFF Research Database (Denmark)

Hasle, Peter; Starheim, Liv; Jensen, Per Langaa

2016-01-01

to such problems. The methodology builds on lean focusing on value stream mapping (VSM) in particular. Groups of employees carry out VSM of selected processes, follow up with the collection of data on the processes and develop suitable solutions. The data from testing of the methodology test shows that VSM...

Computerized visuo-spatial memory test as a supplementary screening test for dementia.

Science.gov (United States)

Maki, Yohko; Yoshida, Hiroshi; Yamaguchi, Haruyasu

2010-06-01

To prepare for a super-aging society, effective dementia screening tests are required. The most salient deficit appearing from the early stages of dementia/Alzheimer's disease (AD) is a deterioration in memory. The Hasegawa Dementia Scale-revised (HDS-R) and the Mini-Mental State Examination (MMSE) are widely used in Japan to screen for dementia. Both place an emphasis on memory function, but neither examines visuo-spatial memory (VSM) function, even though VSM deficits are a sensitive marker for the detection of conversion to dementia. Furthermore, brief tests of VSM that are appropriate for screening have not been standardized. Thus, in the present study, we devised a brief, computer-aided short-term VSM test. Sixty-six aged people were evaluated. Using the Clinical Dementia Rating (CDR), it was found that 29 could be considered normal controls (NC; CDR 0), 10 had mild cognitive impairment (MCI; CDR 0.5), 15 had mild dementia (CDR 1), and 12 had moderate to severe dementia (CDR 2-3). The VSM test estimated how many locations each subject could memorize. Several numbered circles were shown on a monitor and subjects were required to memorize the location of these circles sequentially. After the numbers on the circles on the screen had disappeared, the subjects were required to indicate the circles in ascending order. A touch panel screen was used for this test to make it easier. The HDS-R was applied to subjects with MCI and dementia. The mean (+/-SD) VSM score in subjects with MCI (5.70 +/- 0.96) was significantly lower than that in NC subjects (6.69 +/- 0.82), but significantly higher than that in subjects classified as CDR 1 (4.67 +/- 0.87). There was no significant difference in VSM scores between subjects classified as CDR 1 and CDR 2-3 (3.80 +/- 0.80). There was a moderate significant correlation between VSM and HDS-R scores. In the present study, the VSM test detected differences in VSM function among NC subjects and subjects with MCI and mild dementia. The

Applying value stream mapping techniques to eliminate non-value-added waste for the procurement of endovascular stents.

Science.gov (United States)

Teichgräber, Ulf K; de Bucourt, Maximilian

2012-01-01

OJECTIVES: To eliminate non-value-adding (NVA) waste for the procurement of endovascular stents in interventional radiology services by applying value stream mapping (VSM). The Lean manufacturing technique was used to analyze the process of material and information flow currently required to direct endovascular stents from external suppliers to patients. Based on a decision point analysis for the procurement of stents in the hospital, a present state VSM was drawn. After assessment of the current status VSM and progressive elimination of unnecessary NVA waste, a future state VSM was drawn. The current state VSM demonstrated that out of 13 processes for the procurement of stents only 2 processes were value-adding. Out of the NVA processes 5 processes were unnecessary NVA activities, which could be eliminated. The decision point analysis demonstrated that the procurement of stents was mainly a forecast driven push system. The future state VSM applies a pull inventory control system to trigger the movement of a unit after withdrawal by using a consignment stock. VSM is a visualization tool for the supply chain and value stream, based on the Toyota Production System and greatly assists in successfully implementing a Lean system. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Nanocrystallization in Co67Cr7Fe4Si8B14 Amorphous Alloy Ribbons

Directory of Open Access Journals (Sweden)

Zahra Jamili-Shirvan

2013-12-01

Full Text Available The nanocrystallization of Co67Fe4Cr7Si8B14 amorphous ribbons which prepared by planar flow melt spinning process (PFMS was investigated. Crystallization of the ribbons was studied by differential thermal analysis (DTA, X-ray diffraction (XRD and transmission electron microscopy (TEM. The DTA result of amorphous ribbon at heating rate of 10˚C/min showedoccurrence of phase transitions in two stages. The ribbons were isothermally annealed for 30 minutes in argon atmosphere at different temperatures between 300 and 650ºC with 25ºC steps. The magnetic properties of annealed samples were measured using a vibrating sample magnetometer (VSM. The VSM results revealed that optimum soft magnetic properties occurred at 400ºC. XRD patterns showed that the samples isothermally annealed up to 450ºC were amorphous, while TEM results at 400ºC indicated 7-8 nm mean size nanocrytallites in amorphous matrix and size of the nanocrystallites increased by increasing temperature. Also by X-ray diffraction pattern, precipitation of different phases at higher temperatures confirmed.

Inhibition of Vascular Smooth Muscle Growth via Signaling Crosstalk between AMP-Activated Protein Kinase and cAMP-Dependent Protein Kinase

Directory of Open Access Journals (Sweden)

Joshua Daniel Stone

2012-10-01

Full Text Available Abnormal vascular smooth muscle (VSM growth is central in the pathophysiology of vascular disease yet fully effective therapies to curb this growth are lacking. Recent findings from our lab and others support growth control of VSM by adenosine monophosphate (AMP-based approaches including the metabolic sensor AMP-activated protein kinase (AMPK and cAMP-dependent protein kinase (PKA. Molecular crosstalk between AMPK and PKA has been previously suggested, yet the extent to which this occurs and its biological significance in VSM remains unclear. Considering their common AMP backbone and similar signaling characteristics, we hypothesized that crosstalk exists between AMPK and PKA in the regulation of VSM growth. Using rat primary VSM cells, the AMPK agonist AICAR increased AMPK activity and phosphorylation of the catalytic Thr172 site on AMPK. Interestingly, AICAR also phosphorylated a suspected PKA-inhibitory Ser485 site on AMPK, and these cumulative events were reversed by the PKA inhibitor PKI suggesting possible PKA-mediated regulation of AMPK. AICAR also increased PKA activity in a reversible fashion. The cAMP stimulator forskolin increased PKA activity and completely ameliorated Ser/Thr protein phosphatase-2C activity, suggesting a potential mechanism of AMPK modulation by PKA since inhibition of PKA by PKI reduced AMPK activity. Functionally, AMPK inhibited serum-stimulated cell cycle progression and cellular proliferation; however, PKA failed to do so. Moreover, AMPK and PKA reduced PDGF-β-stimulated VSM cell migration. Collectively, these results show that AMPK is capable of reducing VSM growth in both anti-proliferative and anti-migratory fashions. Furthermore, these data suggest that AMPK may be modulated by PKA and that positive feedback may exist between these two systems. These findings reveal a discrete nexus between AMPK and PKA in VSM and provide basis for metabolically-directed targets in reducing pathologic VSM growth.

Magnetocaloric effect of Gd 5 Si 2 Ge 2 alloys in low magnetic field

Indian Academy of Sciences (India)

The magnetocaloric effect (MCE) is studied by measuring magnetic entropy change ( M) and adiabatic temperature change ( ad) in a magnetic field of 1.5 T using a vibrating sample magnetometer (VSM) and a home-made magnetocaloric effect measuring apparatus, respectively. The maximum M of the alloys ...

Cu 2 + and Al 3 + co-substituted cobalt ferrite

Indian Academy of Sciences (India)

X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emissionscanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM) are used for studying the effect of variation in the Cu–Al substitution and its impact on particle size, magnetic properties such as Ms and Hc.

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Room temperature magnetic properties were studied using vibrating sample magnetometer (VSM) with field strengths up to ± 10 kOe. Lattice constant and crystallite size increased as the annealing temperature was increased. However, the coercivity (c) initially increased and then decreased with the increase of crystallite ...

Magneto-Structural Correlations in Pseudotetrahedral Forms of the [Co(SPh)4]2- Complex Probed by Magnetometry, MCD Spectroscopy, Advanced EPR Techniques, and ab Initio Electronic Structure Calculations.

Science.gov (United States)

Suturina, Elizaveta A; Nehrkorn, Joscha; Zadrozny, Joseph M; Liu, Junjie; Atanasov, Mihail; Weyhermüller, Thomas; Maganas, Dimitrios; Hill, Stephen; Schnegg, Alexander; Bill, Eckhard; Long, Jeffrey R; Neese, Frank

2017-03-06

The magnetic properties of pseudotetrahedral Co(II) complexes spawned intense interest after (PPh 4 ) 2 [Co(SPh) 4 ] was shown to be the first mononuclear transition-metal complex displaying slow relaxation of the magnetization in the absence of a direct current magnetic field. However, there are differing reports on its fundamental magnetic spin Hamiltonian (SH) parameters, which arise from inherent experimental challenges in detecting large zero-field splittings. There are also remarkable changes in the SH parameters of [Co(SPh) 4 ] 2- upon structural variations, depending on the counterion and crystallization conditions. In this work, four complementary experimental techniques are utilized to unambiguously determine the SH parameters for two different salts of [Co(SPh) 4 ] 2- : (PPh 4 ) 2 [Co(SPh) 4 ] (1) and (NEt 4 ) 2 [Co(SPh) 4 ] (2). The characterization methods employed include multifield SQUID magnetometry, high-field/high-frequency electron paramagnetic resonance (HF-EPR), variable-field variable-temperature magnetic circular dichroism (VTVH-MCD), and frequency domain Fourier transform THz-EPR (FD-FT THz-EPR). Notably, the paramagnetic Co(II) complex [Co(SPh) 4 ] 2- shows strong axial magnetic anisotropy in 1, with D = -55(1) cm -1 and E/D = 0.00(3), but rhombic anisotropy is seen for 2, with D = +11(1) cm -1 and E/D = 0.18(3). Multireference ab initio CASSCF/NEVPT2 calculations enable interpretation of the remarkable variation of D and its dependence on the electronic structure and geometry.

Randomized controlled trial of video self-modeling following speech restructuring treatment for stuttering.

Science.gov (United States)

Cream, Angela; O'Brian, Sue; Jones, Mark; Block, Susan; Harrison, Elisabeth; Lincoln, Michelle; Hewat, Sally; Packman, Ann; Menzies, Ross; Onslow, Mark

2010-08-01

In this study, the authors investigated the efficacy of video self-modeling (VSM) following speech restructuring treatment to improve the maintenance of treatment effects. The design was an open-plan, parallel-group, randomized controlled trial. Participants were 89 adults and adolescents who undertook intensive speech restructuring treatment. Post treatment, participants were randomly assigned to 2 trial arms: standard maintenance and standard maintenance plus VSM. Participants in the latter arm viewed stutter-free videos of themselves each day for 1 month. The addition of VSM did not improve speech outcomes, as measured by percent syllables stuttered, at either 1 or 6 months postrandomization. However, at the latter assessment, self-rating of worst stuttering severity by the VSM group was 10% better than that of the control group, and satisfaction with speech fluency was 20% better. Quality of life was also better for the VSM group, which was mildly to moderately impaired compared with moderate impairment in the control group. VSM intervention after treatment was associated with improvements in self-reported outcomes. The clinical implications of this finding are discussed.

Contributed Review: Camera-limits for wide-field magnetic resonance imaging with a nitrogen-vacancy spin sensor

Science.gov (United States)

Wojciechowski, Adam M.; Karadas, Mürsel; Huck, Alexander; Osterkamp, Christian; Jankuhn, Steffen; Meijer, Jan; Jelezko, Fedor; Andersen, Ulrik L.

2018-03-01

Sensitive, real-time optical magnetometry with nitrogen-vacancy centers in diamond relies on accurate imaging of small (≪10-2), fractional fluorescence changes across the diamond sample. We discuss the limitations on magnetic field sensitivity resulting from the limited number of photoelectrons that a camera can record in a given time. Several types of camera sensors are analyzed, and the smallest measurable magnetic field change is estimated for each type. We show that most common sensors are of a limited use in such applications, while certain highly specific cameras allow achieving nanotesla-level sensitivity in 1 s of a combined exposure. Finally, we demonstrate the results obtained with a lock-in camera that paves the way for real-time, wide-field magnetometry at the nanotesla level and with a micrometer resolution.

Thermally activated growth of lath martensite in Fe–Cr–Ni–Al stainless steel

DEFF Research Database (Denmark)

Villa, Matteo; Hansen, Mikkel Fougt; Pantleon, Karen

2015-01-01

The austenite to martensite transformation in a semi-austenitic stainless steel containing 17 wt-%Cr, 7 wt-%Ni and 1 wt-%Al was investigated with vibrating sample magnetometry and electron backscatter diffraction. Magnetometry demonstrated that, within experimental accuracy, martensite formation...... can be suppressed on fast cooling to 77 K as well as on subsequent fast heating to 373 K. Surprisingly, martensite formation was observed during moderate heating from 77 K, instead. Electron backscatter diffraction demonstrated that the morphology of martensite is lath type. The kinetics...... of the transformation is interpreted in terms of athermal nucleation of lath martensite followed by thermally activated growth. It is anticipated that substantial autocatalytic martensite formation occurs during thermally activated growth. The observation of a retardation of the transformation followed by a new...

Synthesis and characterization of cobalt-manganese oxides

Energy Technology Data Exchange (ETDEWEB)

Valencia, J. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis 55455-0153 (United States); Arias, N.P. [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Departamento de Ingenieria Electrica, Electronica y Computacion, Facultad de Ingenieria y Arquitectura, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Giraldo, O. [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Rosales-Rivera, A., E-mail: arosalesr@unal.edu.co [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia)

2012-08-15

Cobalt doped/un-doped manganese oxides materials were synthesized at various doping rates by soft chemical reactions, oxidation-reduction method, which allows generating a metal-mixed oxide. The synthesized materials were characterized using several techniques including chemical analysis, X-rays diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The chemical analysis confirmed the presence of cobalt in the samples. XRD patterns reveal mainly a spinel-like structure and SEM micrographs exhibited morphology with fine aggregate of particles. TGA profiles showed weight loss due to loss of water in a first step, followed by a loss of oxygen from the lattice associated with partial reduction of Mn{sup 4+} to Mn{sup 3+}. VSM was used to measure the magnetization as a function of the applied magnetic field at temperatures T=50 and 300 K. Different magnetic behaviors were observed when cobalt percentage changed in the samples. These behaviors are considered to be related to the size of the particles and composition of the materials. Higher coercive field and lesser magnetization were observed for the sample with higher cobalt content.

Author Contribution to the Pu Handbook II: Chapter 37 LLNL Integrated Sample Preparation Glovebox (TEM) Section

Energy Technology Data Exchange (ETDEWEB)

Wall, Mark A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-10-25

The development of our Integrated Actinide Sample Preparation Laboratory (IASPL) commenced in 1998 driven by the need to perform transmission electron microscopy studies on naturally aged plutonium and its alloys looking for the microstructural effects of the radiological decay process (1). Remodeling and construction of a laboratory within the Chemistry and Materials Science Directorate facilities at LLNL was required to turn a standard radiological laboratory into a Radiological Materials Area (RMA) and Radiological Buffer Area (RBA) containing type I, II and III workplaces. Two inert atmosphere dry-train glove boxes with antechambers and entry/exit fumehoods (Figure 1), having a baseline atmosphere of 1 ppm oxygen and 1 ppm water vapor, a utility fumehood and a portable, and a third double-walled enclosure have been installed and commissioned. These capabilities, along with highly trained technical staff, facilitate the safe operation of sample preparation processes and instrumentation, and sample handling while minimizing oxidation or corrosion of the plutonium. In addition, we are currently developing the capability to safely transfer small metallographically prepared samples to a mini-SEM for microstructural imaging and chemical analysis. The gloveboxes continue to be the most crucial element of the laboratory allowing nearly oxide-free sample preparation for a wide variety of LLNL-based characterization experiments, which includes transmission electron microscopy, electron energy loss spectroscopy, optical microscopy, electrical resistivity, ion implantation, X-ray diffraction and absorption, magnetometry, metrological surface measurements, high-pressure diamond anvil cell equation-of-state, phonon dispersion measurements, X-ray absorption and emission spectroscopy, and differential scanning calorimetry. The sample preparation and materials processing capabilities in the IASPL have also facilitated experimentation at world-class facilities such as the

Author Contribution to the Pu Handbook II: Chapter 37 LLNL Integrated Sample Preparation Glovebox (TEM) Section

International Nuclear Information System (INIS)

Wall, Mark A.

2016-01-01

The development of our Integrated Actinide Sample Preparation Laboratory (IASPL) commenced in 1998 driven by the need to perform transmission electron microscopy studies on naturally aged plutonium and its alloys looking for the microstructural effects of the radiological decay process (1). Remodeling and construction of a laboratory within the Chemistry and Materials Science Directorate facilities at LLNL was required to turn a standard radiological laboratory into a Radiological Materials Area (RMA) and Radiological Buffer Area (RBA) containing type I, II and III workplaces. Two inert atmosphere dry-train glove boxes with antechambers and entry/exit fumehoods (Figure 1), having a baseline atmosphere of 1 ppm oxygen and 1 ppm water vapor, a utility fumehood and a portable, and a third double-walled enclosure have been installed and commissioned. These capabilities, along with highly trained technical staff, facilitate the safe operation of sample preparation processes and instrumentation, and sample handling while minimizing oxidation or corrosion of the plutonium. In addition, we are currently developing the capability to safely transfer small metallographically prepared samples to a mini-SEM for microstructural imaging and chemical analysis. The gloveboxes continue to be the most crucial element of the laboratory allowing nearly oxide-free sample preparation for a wide variety of LLNL-based characterization experiments, which includes transmission electron microscopy, electron energy loss spectroscopy, optical microscopy, electrical resistivity, ion implantation, X-ray diffraction and absorption, magnetometry, metrological surface measurements, high-pressure diamond anvil cell equation-of-state, phonon dispersion measurements, X-ray absorption and emission spectroscopy, and differential scanning calorimetry. The sample preparation and materials processing capabilities in the IASPL have also facilitated experimentation at world-class facilities such as the

Effect of magnetic and thermal properties of iron oxide nanoparticles (IONs) in nitrile butadiene rubber (NBR) latex

Science.gov (United States)

Ong, Hun Tiar; Julkapli, Nurhidayatullaili Muhd; Hamid, Sharifah Bee Abd; Boondamnoen, O.; Tai, Mun Foong

2015-12-01

Nitrile butadiene rubber (NBR) gloves are one of the most important personal protective equipments but they are possible to tear off and contaminate food or pharmaceutical and healthcare products during manufacturing and packaging process. High tendency of torn glove remaining in food or products due to white or light flesh-coloured glove is not easy to be detected by naked eyes. In this paper, iron oxide nanoparticles (IONs) selected as additive for NBR to improve its detectability by mean of magnetic properties. IONs synthesized via precipitation method and compounded with NBR latex before casting on petri dish. The properties of IONs were investigated by X-ray Diffractometry (XRD), Transmission Electron Microscope (TEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). Meanwhile NBR/IONs composites were studied by Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). It observed that, synthesized IONs shows of 25.28 nm crystallite with 25.86 nm semipherical (changed as) shape. Meanwhile, Magnetite and maghemite phase are found in range of 670 cm-1 and 700 cm-1 respectively, which it contributes magnetization saturation of 73.96 emu/g at 10,000 G by VSM. Thermal stability and magnetic properties were increased with incorporating IONs into NBR latex up to 20 phr. NBR/IONs 5 phr has the optimum thermal stability, lowest glass transition temperature (-14.83 °C) and acceptable range of magnetization saturation (3.83 emu/g at 10,000 G) to form NBR gloves with magnetic detectability.

Separation/Preconcentration and Speciation Analysis of Trace Amounts of Arsenate and Arsenite in Water Samples Using Modified Magnetite Nanoparticles and Molybdenum Blue Method

Directory of Open Access Journals (Sweden)

Mohammad Ali Karimi

2014-01-01

Full Text Available A new, simple, and fast method for the separation/preconcentration and speciation analysis of arsenate and arsenite ions using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs followed by molybdenum blue method is proposed. The method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in different samples was determined as As(V after oxidation of As(III to As(V using potassium permanganate. The arsenic concentration has been determined by UV-Visible spectrometric technique based on molybdenum blue method and amount of As(III was calculated by subtracting the concentration of As(V from total arsenic concentration. MNPs and ACMNPs were characterized by VSM, XRD, SEM, and FT-IR spectroscopy. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD of arsenate were 175 (for 350 mL of sample solution, 0.028 μg mL−1, 0.090–4.0 μg mL−1, and 2.8% (for 2.0 μg mL−1, n=7, respectively. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of arsenic in different water samples and suitable recoveries were obtained.

Low temperature synthesis of nanosized Mn1–xZnxFe2O4 ferrites ...

Indian Academy of Sciences (India)

There is a systematic decrease in the particle size, Curie temperature and magnetization with the increase in the Zn2+ ion doping, measured using magneto thermal gravimetric analysis (MTGA) and vibrating sample magnetometer (VSM), respectively. The lattice constant is found to be constantly decreasing till = 0.6 and ...

Size Induced Structural and Magnetic Properties of Nanostructured ...

African Journals Online (AJOL)

Their structural and magnetic properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) measurements. The average crystallite size of CoFe2O4was observed to increase from 23 to 65 nm as the annealing temperature was increased from ...

Effect of Particle Size on the Structural and Magnetic Properties of ...

African Journals Online (AJOL)

The obtained ZnFe2O4 nano powders were thermally annealed from 300 to 600 °C. The structural and magnetic characterization were measured using X-ray diffraction (XRD), scanning electron microscope (SEM), IR measurements and vibrating sample magnetometer (VSM). XRD patterns clearly showed the formation of ...

Video Self-Modeling

Science.gov (United States)

Buggey, Tom; Ogle, Lindsey

2012-01-01

Video self-modeling (VSM) first appeared on the psychology and education stage in the early 1970s. The practical applications of VSM were limited by lack of access to tools for editing video, which is necessary for almost all self-modeling videos. Thus, VSM remained in the research domain until the advent of camcorders and VCR/DVD players and,…

Determination of fluoroquinolone antibiotics in environmental water samples based on magnetic molecularly imprinted polymer extraction followed by liquid chromatography-tandem mass spectrometry

International Nuclear Information System (INIS)

Chen Ligang; Zhang Xiaopan; Xu Yang; Du Xiaobo; Sun Xin; Sun Lei; Wang Hui; Zhao Qi; Yu Aimin; Zhang Hanqi; Ding Lan

2010-01-01

A simple method based on magnetic separation for selective extraction of fluoroquinolones (FQs) from environmental water samples has been developed using magnetic molecularly imprinted polymer (MMIP) as sorbent. The MMIP has been prepared using ciprofloxacin as template molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linking agent and Fe 3 O 4 magnetite as magnetic component. The polymer has been characterized by scanning electron microscopy, Fourier-transform infrared spectrometry and vibrating sample magnetometry. Various parameters affecting the extraction efficiency were evaluated in order to achieve optimal concentration and reduce non-specific interactions. The analytes desorbed from the polymers were determined by liquid chromatography-tandem mass spectrometry. The matrix effect was evaluated by using different washing solvents for removing interfering compounds from the MMIPs after sample loading. Under the optimal conditions, the linearity of the method obtained is in the range of 20-2000 ng L -1 . The detection limits of FQs are in the range of 3.2-6.2 ng L -1 . The relative standard deviations of intra- and inter-day tests ranging from 2.5 to 7.2% and from 3.6 to 9.1% are obtained. In all three spiked levels (20, 100 and 200 ng L -1 ), the recoveries of FQs are in the range of 76.3-94.2%. The proposed method was successfully applied to determine FQs including ciprofloxacin, enrofloxacin, lomefloxacin, levofloxacin, fleroxacin and sparfloxacin in different water samples, such as lake water, river water, primary and final sewage effluent. Ciprofloxacin and fleroxacin were found in primary and final sewage effluent samples with the contents in the range of 26-87 ng L -1 .

Determination of fluoroquinolone antibiotics in environmental water samples based on magnetic molecularly imprinted polymer extraction followed by liquid chromatography-tandem mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Chen Ligang; Zhang Xiaopan; Xu Yang [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, Jilin (China); Du Xiaobo; Sun Xin [College of Physics, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Sun Lei; Wang Hui; Zhao Qi; Yu Aimin; Zhang Hanqi [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, Jilin (China); Ding Lan, E-mail: dinglan@jlu.edu.cn [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, Jilin (China)

2010-03-03

A simple method based on magnetic separation for selective extraction of fluoroquinolones (FQs) from environmental water samples has been developed using magnetic molecularly imprinted polymer (MMIP) as sorbent. The MMIP has been prepared using ciprofloxacin as template molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linking agent and Fe{sub 3}O{sub 4} magnetite as magnetic component. The polymer has been characterized by scanning electron microscopy, Fourier-transform infrared spectrometry and vibrating sample magnetometry. Various parameters affecting the extraction efficiency were evaluated in order to achieve optimal concentration and reduce non-specific interactions. The analytes desorbed from the polymers were determined by liquid chromatography-tandem mass spectrometry. The matrix effect was evaluated by using different washing solvents for removing interfering compounds from the MMIPs after sample loading. Under the optimal conditions, the linearity of the method obtained is in the range of 20-2000 ng L{sup -1}. The detection limits of FQs are in the range of 3.2-6.2 ng L{sup -1}. The relative standard deviations of intra- and inter-day tests ranging from 2.5 to 7.2% and from 3.6 to 9.1% are obtained. In all three spiked levels (20, 100 and 200 ng L{sup -1}), the recoveries of FQs are in the range of 76.3-94.2%. The proposed method was successfully applied to determine FQs including ciprofloxacin, enrofloxacin, lomefloxacin, levofloxacin, fleroxacin and sparfloxacin in different water samples, such as lake water, river water, primary and final sewage effluent. Ciprofloxacin and fleroxacin were found in primary and final sewage effluent samples with the contents in the range of 26-87 ng L{sup -1}.

Attenuation of chondrogenic transformation in vascular smooth muscle by dietary quercetin in the MGP-deficient mouse model.

Directory of Open Access Journals (Sweden)

Kelly E Beazley

Full Text Available Cartilaginous metaplasia of vascular smooth muscle (VSM is characteristic for arterial calcification in diabetes and uremia and in the background of genetic alterations in matrix Gla protein (MGP. A better understanding of the molecular details of this process is critical for the development of novel therapeutic approaches to VSM transformation and arterial calcification.This study aimed to identify the effects of bioflavonoid quercetin on chondrogenic transformation and calcification of VSM in the MGP-null mouse model and upon TGF-β3 stimulation in vitro, and to characterize the associated alterations in cell signaling.Molecular analysis revealed activation of β-catenin signaling in cartilaginous metaplasia in Mgp-/- aortae in vivo and during chondrogenic transformation of VSMCs in vitro. Quercetin intercepted chondrogenic transformation of VSM and blocked activation of β-catenin both in vivo and in vitro. Although dietary quercetin drastically attenuated calcifying cartilaginous metaplasia in Mgp-/- animals, approximately one-half of total vascular calcium mineral remained as depositions along elastic lamellae.Quercetin is potent in preventing VSM chondrogenic transformation caused by diverse stimuli. Combined with the demonstrated efficiency of dietary quercetin in preventing ectopic chondrogenesis in the MGP-null vasculature, these findings indicate a potentially broad therapeutic applicability of this safe for human consumption bioflavonoid in the therapy of cardiovascular conditions linked to cartilaginous metaplasia of VSM. Elastocalcinosis is a major component of MGP-null vascular disease and is controlled by a mechanism different from chondrogenic transformation of VSM and not sensitive to quercetin.

Molecular pathophysiology and pharmacology of the voltage-sensing module of neuronal ion channels.

Science.gov (United States)

Miceli, Francesco; Soldovieri, Maria Virginia; Ambrosino, Paolo; De Maria, Michela; Manocchio, Laura; Medoro, Alessandro; Taglialatela, Maurizio

2015-01-01

Voltage-gated ion channels (VGICs) are membrane proteins that switch from a closed to open state in response to changes in membrane potential, thus enabling ion fluxes across the cell membranes. The mechanism that regulate the structural rearrangements occurring in VGICs in response to changes in membrane potential still remains one of the most challenging topic of modern biophysics. Na(+), Ca(2+) and K(+) voltage-gated channels are structurally formed by the assembly of four similar domains, each comprising six transmembrane segments. Each domain can be divided into two main regions: the Pore Module (PM) and the Voltage-Sensing Module (VSM). The PM (helices S5 and S6 and intervening linker) is responsible for gate opening and ion selectivity; by contrast, the VSM, comprising the first four transmembrane helices (S1-S4), undergoes the first conformational changes in response to membrane voltage variations. In particular, the S4 segment of each domain, which contains several positively charged residues interspersed with hydrophobic amino acids, is located within the membrane electric field and plays an essential role in voltage sensing. In neurons, specific gating properties of each channel subtype underlie a variety of biological events, ranging from the generation and propagation of electrical impulses, to the secretion of neurotransmitters and to the regulation of gene expression. Given the important functional role played by the VSM in neuronal VGICs, it is not surprising that various VSM mutations affecting the gating process of these channels are responsible for human diseases, and that compounds acting on the VSM have emerged as important investigational tools with great therapeutic potential. In the present review we will briefly describe the most recent discoveries concerning how the VSM exerts its function, how genetically inherited diseases caused by mutations occurring in the VSM affects gating in VGICs, and how several classes of drugs and toxins

Effect of iron content on permeability and power loss characteristics ...

Indian Academy of Sciences (India)

Administrator

have been measured by vibrating sample magnetometer (VSM). The permeability of cadmium doped lithium ferrites exhibited higher values than zinc doped lithium ferrites. The power loss of cadmium doped lithium ferrites is lesser as compared to zinc doped lithium ferrites in the frequency range of 50–5000 kHz and at flux.

Investigation of magnetically enhanced swelling behaviour of ...

Indian Academy of Sciences (India)

mer produced by many plants as a source of stored energy. (Corre et al 2010). It is an .... A vibrating-sample magnetometer (VSM) was used to study the magnetic ... were prepared: saline water (0·9 g NaCl), synthetic urine. (0·8 g NaCl, 0·10 g ...

In situ microemulsion synthesis of hydroxyapatite-MgFe{sub 2}O{sub 4} nanocomposite as a magnetic drug delivery system

Energy Technology Data Exchange (ETDEWEB)

Foroughi, Firoozeh [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of); Hassanzadeh-Tabrizi, S.A., E-mail: tabrizi1980@gmail.com [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of); Bigham, Ashkan [Advanced Materials Research Center, Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of)

2016-11-01

In this study, an innovative synthesis process has been developed to produce hydroxyapatite-magnesium ferrite (HA-MgFe{sub 2}O{sub 4}) nanocomposite. In addition, the effect of calcination temperature on drug delivery behavior of produced samples was investigated. HA-MgFe{sub 2}O{sub 4} nanocomposite was prepared via one-step modified reverse microemulsion synthesis route. The resulting products were characterized by X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and Brunauer–Emmett–Teller surface area analysis (BET). The calcined samples at 500 and 700 °C demonstrated mesoporous characteristics and large specific surface areas of 88 and 32 m{sup 2}/g, respectively. TEM and VSM results showed that the nanocomposite calcined at 700 °C has core–shell morphology and a maximum saturation magnetization of 9.47 emu g{sup −1}. - Highlights: • A one-step modified reverse microemulsion method has been used to produce hydroxyapatite-magnesium ferrite. • Nanocomposites were loaded with ibuprofen as a magnetic drug delivery system. • The drug release behavior of nanocomposites were studied at different calcination temperature.

Magnetic properties of thin films obtained by ion implantation of 3d metals in polyethylene-terephthalate

International Nuclear Information System (INIS)

Petukhov, V.Yu.; Ibragimova, M.I.; Khabibullina, N.R; Zheglov, E.P.; Muller, R.

2002-01-01

Polymer films containing small metal particles have been attracting particular interest because of their unique properties. Implantation of metal ions in polymers is one of the methods to synthesize metal-polymer nano-composite materials. Ion implantation makes possible the magnetic nano-structures with controlled parameters. Previously, we showed that 3d-metal implantation into numerous polymers (polymethylmethacrylate, phosphorus containing polymethylmethacrylate) resulted in the formation of a composite film consisting of metal nanoparticles buried in an implanted layer. The particles are usually found to be distributed randomly in the surface layer. It has been established that structural peculiarities, phase composition, and magnetic properties of synthesized metal-polymer systems depend on the type of the initial polymer matrix, ion types, as well as conditions of ion implantation. In the present study we have been prepared thin metal-polymer composite films by ion-beam implantation of Fe + and Co + ions in polyethylene terephthalate. The implantation of 40 keV ions at room temperature with doses from 2·10 1 6 to 3·10 17 cm -2 have been performed, with the ion current density not exceeding 10 μA/cm 2 . The magnetic properties have been investigated both by ferromagnetic resonance (FMR) and vibrating sample magnetometry (VSM). FMR spectra were recorded using magnetic radio spectrometer Varian E-12 with frequency of 9.5 GHz at room temperature. The dependencies of FMR spectra on orientation have been measured for all samples. Measurements were carried out for two orientations of the sample, normal direction of the films being either parallel or perpendicular to dc magnetic field. The values of the effective magnetization were calculated from orientation dependencies. Thin ferromagnetic films (TFF) have been shown to form for samples with both implanted ions. For samples implanted with Co + ions, the appearance of FMR lines occurs at doses markedly greater

Complex regional pain syndrome (CRPS) impairs visuospatial perception,whereas post-herpetic neuralgia does not: possible implications for supraspinal mechanism of CRPS.

Science.gov (United States)

Uematsu, Hironobu; Sumitani, Masahiko; Yozu, Arito; Otake, Yuko; Shibata, Masahiko; Mashimo, Takashi; Miyauchi, Satoru

2009-11-01

Complex regional pain syndrome (CRPS) patients show impaired visuospatial perception in the dark, as compared to normal patients with acute nociceptive pain. The purpose of this study is 2-fold: (i) to ascertain whether this distorted visuospatial perception is related to the chronicity of pain, and (ii) to analyse visuospatial perception of CRPS in comparison with another neuropathic pain condition. We evaluated visual subjective body-midline (vSM) representation in 27 patients with post-herpetic neuralgia (PHN) and 22 with CRPS under light and dark conditions. A red laser dot was projected onto a screen and moved horizontally towards the sagittal plane of the objective body-midline (OM). Each participant was asked to direct the dot to a position where it crossed their vSM. The distance between the vSM and OM was analysed to determine how and in which direction the vSM deviated. Under light condition, all vSM judgments approximately matched the OM. However, in the dark, CRPS patients, but not PHN patients, showed a shifted vSM towards the affected side. We demonstrated that chronic pain does not always impair visuospatial perception. The aetiology of PHN is limited to the peripheral nervous system, whereas the distorted visuospatial perception suggests a supraspinal aetiology of CRPS.

Study on Geomagnetic Space Observatories

DEFF Research Database (Denmark)

Bak, Thomas; Blanke, M.; Wisniewski, Rafal

1996-01-01

Magnetometry was one of the objectives of the Aristoteles mission endorsed at the 1991 Earth Observation User Consultation meeting.......Magnetometry was one of the objectives of the Aristoteles mission endorsed at the 1991 Earth Observation User Consultation meeting....

Electronic and magnetic properties study of neptunium compounds: NpX{sub 3} and Np{sub 2}T{sub 2}X by Moessbauer effect, neutrons diffraction and Squid magnetometry; Etude des proprietes magnetiques et electroniques de composes de neptunium NpX{sub 3} et Np{sub 2}T{sub 2}X par spectrometrie mossbauer, diffraction de neutrons et magnetometrie squid

Energy Technology Data Exchange (ETDEWEB)

Colineau, E.

1996-07-11

This work is a contribution to the study of magnetic and electronic properties of the intermetallic compounds: NpX{sub 3} (X= Al, Ga, In, Sn) and Np{sub 2}T{sub 2}X (T= Co, Ni, Ru, Rh, Pd, Pt; X= In, Sn). These properties have been determined by Moessbauer effect, neutron diffraction and Squid magnetometry. The obtained results for NpX{sub 3} show particularly that NpAl{sub 3} orders in a type II (k= 1/2 1/2 1/2) antiferromagnetic structure at T{sub N} {approx_equal} 37 K. The antiferromagnetic phase NpGa{sub 3} orders in a type II too and the magnetic moments carried by neptunium in the ferromagnetic phase are oriented along the (111) axes. The two NpIN{sub 3} magnetic phases observed by Moessbauer effect (4.2 K-10 K and 10 K- 14 K) are identified by neutron diffraction as ferromagnetic and antiferromagnetic (k= 3/8 3/8 3/8). In this last phase the moments are oriented along the (111) axes. The magnetization measures on monocrystals show a weak anisotropy with (111) at all the temperatures and reveal the presence of a third magnetic phase between 8.2 and 10 K. At last, the fundamental state of the compounds NpAl{sub 3}, NpGa{sub 3} and NpIn{sub 3} is attributed to the {Gamma}{sub 5} crystal field and the strong reduction of the ordered moment in NpSn{sub 3} to a Kondo effect. Concerning the Np{sub 2}T{sub 2}X compounds, the Moessbauer effect measures have revealed that eight of these compounds order and three do not order. (O.M.). 239 refs.

Scaling analysis of [Fe(pyrazole)4]2[Nb(CN)8] molecular magnet

International Nuclear Information System (INIS)

Konieczny, P.; Pełka, R.; Zieliński, P.M.; Pratt, F.L.; Pinkowicz, D.; Sieklucka, B.; Wasiutyński, T.

2013-01-01

The critical behaviour of the three dimensional (3D) molecular magnet {[Fe II (pirazol) 4 ] 2 [Nb IV (CN) 8 ]·4H 2 O} n has been studied with the use of experimental techniques such as ac magnetometry and zero field μSR spectroscopy. The sample orders magnetically below T c =7.8 K. The measurements allowed to determine static exponents β, γ, and the dynamic exponent w. The resulting exponent values indicate that the studied system belongs to the universality class of the 3D Heisenberg model. - Highlights: • The critical behaviour of {[Fe II (pirazol) 4 ] 2 [Nb IV (CN) 8 ]∙4H 2 O} n has been studied. • Critical exponents β, γ, and w were obtained from ac magnetometry and ZF µSR data. • All obtained values of critical exponents are close to the 3D Heisenberg model

Gd3+ doped Mn-Zn soft ferrite nanoparticles: Superparamagnetism and its correlation with other physical properties

Science.gov (United States)

Thakur, Prashant; Sharma, Rohit; Sharma, Vineet; Barman, P. B.; Kumar, Manoj; Barman, Dipto; Katyal, S. C.; Sharma, Pankaj

2017-06-01

Superparamagnetic nanoparticles are very important in biomedicine due to their various applications like drug delivery, gene delivery in the body and also used for hyperthermia. In the present work, superparamagnetic nanoparticles of Mn0.5Zn0.5GdxFe2-xO4 (x = 0, 0.025, 0.050, 0.075, 0.1) ferrites have been prepared by co-precipitation method. Thorough characterizations (XRD, FTIR, FE-SEM, EDS, VSM and fluorescence spectroscopy) have proved the formation of cubical spinel superparamagnetic nanoparticles of soft ferrites. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. With the addition of Gd3+ nanoparticles have shown the superparamagnetism at room temperature confirmed by VSM analysis. Photoluminescence (PL) spectra shows a blue shift (for x = 0.025, 0.075) which may be due to quantum confinement.

synthesis, characterization, thermal behavior and antimicrobial

African Journals Online (AJOL)

It is used for joint and muscle pain than other pain killer and has been ... Benzoic acid and its salts are used to preserve food from growth of .... vibrating sample magnetometer, VSM EG&G model 155 at room temperature and the data were ..... effective antimicrobial agent with less effect on normal cell lines at low levels.

Dependence of magnetic and structural properties of Ni 0.5 M 0.5 Fe ...

African Journals Online (AJOL)

Ni0.5M0.5Fe2O4 (M = Co, Cu) ferrite nanoparticles were synthesized using citrate precursor method. The citrate precursor was annealed at temperatures 400oC, 450oC, 500oC and 550oC. The annealed powders were characterized using X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM). Observed ...

Preparation and characterization of Co9S8 nanocrystalline and ...

Indian Academy of Sciences (India)

Wintec

vibrating sample magnetometer (VSM) and laser Raman spectrometer. The results show that the as-prepared. Co9S8 nanocrystal with a size of 6 nm take on weak paramagnetism at room temperature. The lengths and dia- meters of the nanorods were about 4 μm and 200 nm, respectively. The reason for the relative lower ...

Microesferas poliméricas magnéticas à base de estireno e divinilbenzeno com morfologia casca e núcleo Magnetic polymeric microspheres based on styrene and divinylbenzene with core-shell morphology

Directory of Open Access Journals (Sweden)

Washington J. F. Formiga

2013-01-01

sample magnetometry (VSM. All methods tested to forming the poly(styrene-co-divinylbenzene shell have produced particles with diameter larger than the core. This result indicates the formation of core-shell morphology. The morphologic control was only obtained with resins RR48/1 and RR48/3. Moreover, the method where the emulsion of styrene and divinylbenzene was added in one step, followed by 48 hours of core swelling at 10 °C (RR48/1, gave the highest yield (64%. All microspheres were susceptible to a magnet.

Ferromagnetic resonance parameters of ball-milled Ni-Zn ferrite nanoparticles

International Nuclear Information System (INIS)

Rao, B. Parvatheeswara; Caltun, Ovidiu; Dumitru, Ioan; Spinu, Leonard

2006-01-01

Ferrite nanoparticles of the size about 6 nm have been made by using high-energy ball mill on the sintered pellets of the system Ni 0.65 Zn 0.375 In x Ti 0.025 Fe 1.95- x O 4 . XRD, VSM and FMR techniques were used for structural and magnetic characterizations of the samples. The magnetic characteristics of indium-doped samples are compared with those for bulk samples. The differences are discussed in terms of the particle size and small-particle magnetism

structural and magnetic properties of Fe(20Å /Ag(xÅ/Fe(20Å hetro-multilayers

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P Ghahramaninezhad

2015-07-01

Full Text Available We have deposited Fe/Ag/Fe multilayer by physical vapor deposition (PVDmethod in different Ag thickness as spacer working in a vacuum of 2×10-6mbar. The structural properties , magnetic response of the samples at low temperatures and room temperature was investigated by XRD, physical properties measurement system (PPMS and vibrating sample magnetometer (VSM respectively. Hysteresis loops show that the easy axis of magnetization is in plane of the film . Also the magnetization and Hc of samples decrease with increasing temperature.

MOLECULAR PATHOPHYSIOLOGY AND PHARMACOLOGY OF THE VOLTAGE-SENSING DOMAIN OF NEURONAL ION CHANNELS

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Francesco eMiceli

2015-07-01

Full Text Available Voltage-gated ion channels (VGIC are membrane proteins that switch from a closed to open state in response to changes in membrane potential, thus enabling ion fluxes across the cell membranes. The mechanism that regulate the structural rearrangements occurring in VGIC in response to changes in membrane potential still remains one of the most challenging topic of modern biophysics. Na+, Ca2+ and K+ voltage-gated channels are structurally formed by the assembly of four similar domains, each comprising six transmembrane segments. Each domain can be divided in two main regions: the Pore Module (PM and the Voltage-Sensing Module (VSM. The PM (helices S5 and S6 and intervening linker is responsible for gate opening and ion selectivity; by contrast, the VSM, comprising the first four transmembrane helices (S1-S4, undergoes the first conformational changes in response to membrane voltage. In particular, the S4 segment of each domain, which contains several positively charged residues interspersed with hydrophobic amino acids, is located within the membrane electric field and plays an essential role in voltage sensing. In neurons, specific gating properties of each channel subtype underlie a variety of biological events, ranging from the generation and propagation of electrical impulses, to the secretion of neurotransmitters, to the regulation of gene expression. Given the important functional role played by the VSM in neuronal VGICs, it is not surprising that various VSM mutations affecting the gating process of these channels are responsible for human diseases, and that compounds acting on the VSM have emerged as important investigational tools with great therapeutic potential. In the present review we will briefly describe the most recent discoveries concerning how the VSM exerts its function, how genetically inherited diseases caused by mutations occurring in the VSM affects gating in VGICs, and how several classes of drugs and toxins selectively

Structural chemistry and magnetic properties of the perovskite SrLa{sub 2}Ni{sub 2}TeO{sub 9}

Energy Technology Data Exchange (ETDEWEB)

Paria Sena, Robert; Hadermann, Joke [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Chin, Chun-Mann; Hunter, Emily C. [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Battle, Peter D., E-mail: peter.battle@chem.ox.ac.uk [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom)

2016-11-15

A polycrystalline sample of SrLa{sub 2}Ni{sub 2}TeO{sub 9} has been synthesized using a standard ceramic method and characterized by neutron diffraction, magnetometry and electron microscopy. The compound adopts a monoclinic, perovskite-like structure with space group P2{sub 1}/n and unit cell parameters a=5.6008(1), b=5.5872(1), c=7.9018(2) Å, β=90.021(6)° at room temperature. The two crystallographically-distinct B sites are occupied by Ni{sup 2+} and Te{sup 6+} in ratios of 83:17 and 50:50. Both ac and dc magnetometry suggest that the compound is a spin glass below 35 K but the neutron diffraction data show that some regions of the sample are antiferromagnetic. Electron microscopy revealed twinning on a nanoscale and local variations in composition. These defects are thought to be responsible for the presence of two distinct types of antiferromagnetic ordering. - Highlights: • Coexistence of spin-glass and ordered phases. • Local inhomogeneity despite long-range inhomogeneity. • Contrasting magnetic properties of SrLa{sub 2}Ni{sub 2}TeO{sub 9} and La{sub 3}Ni{sub 2}SbO{sub 9}.

Magnetic and topographical modifications of amorphous Co–Fe thin films induced by high energy Ag{sup 7+} ion irradiation

Energy Technology Data Exchange (ETDEWEB)

Pookat, G.; Hysen, T. [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India); Al-Harthi, S.H.; Al-Omari, I.A. [Department of Physics, Sultan Qaboos University, Muscat, P.O. Box 36, Code 123 (Oman); Lisha, R. [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India); Avasthi, D.K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Anantharaman, M.R., E-mail: mra@gmail.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India)

2013-09-01

We have investigated the effects of swift heavy ion irradiation on thermally evaporated 44 nm thick, amorphous Co{sub 77}Fe{sub 23} thin films on silicon substrates using 100 MeV Ag{sup 7+} ions fluences of 1 × 10{sup 11} ions/cm{sup 2}, 1 × 10{sup 12} ions/cm{sup 2}, 1 × 10{sup 13} ions/cm{sup 2}, and 3 × 10{sup 13} ions/cm{sup 2}. The structural modifications upon swift heavy irradiation were investigated using glancing angle X-ray diffraction. The surface morphological evolution of thin film with irradiation was studied using Atomic Force Microscopy. Power spectral density analysis was used to correlate the roughness variation with structural modifications investigated using X-ray diffraction. Magnetic measurements were carried out using vibrating sample magnetometry and the observed variation in coercivity of the irradiated films is explained on the basis of stress relaxation. Magnetic force microscopy images are subjected to analysis using the scanning probe image processor software. These results are in agreement with the results obtained using vibrating sample magnetometry. The magnetic and structural properties are correlated.

Effects of Temperature on the Microstructure and Magnetic Property of Cr-Doped ZnO DMS Prepared by Hydrothermal Route Assisted by Pulsed Magnetic Fields

Directory of Open Access Journals (Sweden)

Shiwei Wang

2013-01-01

Full Text Available In the present work, Cr-doped ZnO diluted magnetic semiconductor was synthesized by hydrothermal method under pulsed magnetic fields. The samples were characterized by XRD, SEM, VSM, Raman, and XPS techniques. Results demonstrated that Zn ions in the ZnO crystal lattice were partially displaced by Chromium (III ions. All samples show room temperature ferromagnetism which was enhanced by pulsed magnetic fields. The mechanism of ferromagnetism of Cr-doped ZnO particles was discussed.

Magnetic solid-phase extraction of five pyrethroids from environmental water samples followed by ultrafast liquid chromatography analysis.

Science.gov (United States)

Yu, Xi; Sun, Ying; Jiang, Chunzhu; Sun, Xiumin; Gao, Yan; Wang, Yuanpeng; Zhang, Hanqi; Song, Daqian

2012-08-30

In this study, the polystyrene-coated magnetic nanoparticles (MNPs/PSt) were successfully prepared and characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and vibrating sample magnetometry. The as-prepared MNPs/PSt were used as the adsorbent in magnetic solid phase extraction of five pyrethroids, including lambda-cyhalothrin, deltamethrin, esfenvalerate, permethrin, bifenthrin, in environmental water samples. The five pyrethroids were determined by ultra fast liquid chromatography-ultraviolet spectrometry. The influencing factors, including amount of MNPs/Pst, extraction time, pH value, type and volume of desorption solvent and desorption time, were examined and optimized. The extraction recoveries obtained with merely 50mg of MNPs/Pst were very satisfactory. The whole extraction process could be completed within 0.5h. The MNPs/PSt can be reused after an easy washing process. Thus, a simple, green, economical, time saving and effective method for pyrethroids analysis in environmental water samples was established. A high enrichment factor of 500 was achieved and the limits of detection for lambda-cyhalothrin, deltamethrin, esfenvalerate, permethrin, bifenthrin were 0.015±0.001 ng mL(-1), 0.012±0.001 ng mL(-1), 0.026±0.001 ng mL(-1), 0.020±0.001 ng mL(-1), 0.013±0.001 ng mL(-1), respectively. Recoveries obtained by analyzing spiked water samples at three concentration levels (0.100±0.001 ng mL(-1), 1.000±0.001 ng mL(-1), 10.000±0.001 ng mL(-1)) were between 78.97±8.38% and 96.05±8.38%. The standard curves for the five pyrethroids showed good linearity with the correlation coefficients in the range of 0.9994-0.9999. The intra-day and inter-day precision were satisfactory with the RSDs in the range of 2.05-5.52% and 2.73-8.38%, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of 100 MeV Ag{sup +7} ion irradiation on the bulk and surface magnetic properties of Co–Fe–Si thin films

Energy Technology Data Exchange (ETDEWEB)

Hysen, T., E-mail: hysenthomas@gmail.com [Department of Physics, Cochin University of Science and Technology, Cochin 682 022, Kerala (India); Department of Physics, Christian College, Chengannur, Kerala 689 122 (India); Geetha, P. [Department of Physics, Cochin University of Science and Technology, Cochin 682 022, Kerala (India); Al-Harthi, Salim; Al-Omari, I.A. [Department of Physics, College of Science, Sultan Qaboos University, Al Khod 123 (Oman); Lisha, R. [Department of Physics, Cochin University of Science and Technology, Cochin 682 022, Kerala (India); Ramanujan, R.V. [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639 798 (Singapore); Sakthikumar, D. [Graduate School of Interdisciplinary New Science, Toyo University, Kawagoe (Japan); Avasthi, D.K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Anantharaman, M.R., E-mail: mra@cusat.ac.in [Department of Physics, Cochin University of Science and Technology, Cochin 682 022, Kerala (India)

2014-12-15

Thin films of Co–Fe–Si were vacuum evaporated on pre-cleaned float glass substrates employing thermal evaporation. The films were subsequently irradiated with 100 MeV Ag{sup +7} ions at fluences of 1×10{sup 11}, 1×10{sup 12} and 1×10{sup 13} ions/cm{sup 2}. The pristine and irradiated samples were subjected to surface analysis using Atomic Force Microscopy (AFM), Vibrating Sample Magnetometry (VSM) and Magneto Optic Kerr Effect (MOKE) measurements. The as deposited film has a root mean square roughness (Rq) of 8.9 nm and an average roughness of (Ra) 5.6 nm. Irradiation of the as deposited films with 100 MeV Ag{sup 7+} ions modifies the surface morphology. Irradiating with ions at fluences of 1×10{sup 11} ions/cm{sup 2} smoothens the mesoscopic hill-like structures, and then, at 1×10{sup 12} ions/cm{sup 2} new surface structures are created. When the fluence is further increased to 1×10{sup 13} ions/cm{sup 2} an increase in the surface roughness is observed. The MOKE loop of as prepared film indicated a squareness ratio of 0.62. As the film is irradiated with fluences of 1×10{sup 11} ions/cm{sup 2}, 1×10{sup 12} ions/cm{sup 2} and 1×10{sup 13} ions/cm{sup 2} the squareness ratio changes to 0.76, 0.8 and 0.86 respectively. This enhancement in squareness ratio towards 1 is a typical feature when the exchange interaction starts to dominates the inherent anisotropies in the system. The variation in surface magnetisation is explained based on the variations in surface roughness with swift heavy ion (SHI) irradiation. - Highlights: • We have irradiated thermally evaporated Co–Fe–Si thin films on glass substrate with 100 MeV Ag{sup +7} ions using the 15 UD Pelletron Accelerator at IUAC, New Delhi, India. • Surface morphology and magnetic characteristics of the films can be altered with ion irradiation. • It was observed that the variation in surface magnetic properties correlates well with the changes in surface morphology, further reiterating the

Fabrication of graphene/Fe3O4@polythiophene nanocomposite and its application in the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from environmental water samples.

Science.gov (United States)

Mehdinia, Ali; Khodaee, Nader; Jabbari, Ali

2015-04-08

Polythiophene (PT) was used as a surface modifier of graphene/Fe3O4 (G/Fe3O4) composite to increase merit of it, and also overcome some limitations and disadvantages of using G/Fe3O4 alone as solid phase extraction (SPE) sorbent. An in-situ chemical polymerization method was employed to prepare G/Fe3O4@PT nanocomposites. Application of this newly designed material in the magnetic SPE (MSPE) of polycyclic aromatic hydrocarbons (PAHs), as model analytes, in the environmental water samples was investigated. The characterization of the hybrid material was performed using transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray analysis, Fourier transform-infrared (FT-IR) spectroscopy and vibrating sample magnetometry. Seven important parameters, affecting the extraction efficiency of PAHs, including: amount of adsorbent, adsorption and desorption times, type and volume of the eluent solvent, initial sample volume and salt content of the sample were evaluated. The optimum extraction conditions were obtained as: 4 min for extraction time, 20 mg for sorbent amount, 100mL for initial sample volume, toluene as desorption solvent, 0.6 mL for desorption solvent volume, 6 min for desorption time and 30% (w/v) for NaCl concentration. Good performance data were obtained at the optimized conditions. Detection limits were in the range of 0.009-0.020 μg L(-1) in the real matrix. The calibration curves were linear over the concentration ranges from 0.03 to 80 μg L(-1) with correlation coefficients (R(2)) between 0.995 and 0.998 for all the analytes. Relative standard deviations were ranged from 4.3 to 6.3%. Appropriate recovery values, in the range of 83-107%, were also obtained for the real sample analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

Associations of learning style with cultural values and demographics in nursing students in Iran and Malaysia.

Science.gov (United States)

Abdollahimohammad, Abdolghani; Ja'afar, Rogayah

2015-01-01

The goal of the current study was to identify associations between the learning style of nursing students and their cultural values and demographic characteristics. A non-probability purposive sampling method was used to gather data from two populations. All 156 participants were female, Muslim, and full-time degree students. Data were collected from April to June 2010 using two reliable and validated questionnaires: the Learning Style Scales and the Values Survey Module 2008 (VSM 08). A simple linear regression was run for each predictor before conducting multiple linear regression analysis. The forward selection method was used for variable selection. P-values ≤0.05 and ≤0.1 were considered to indicate significance and marginal significance, respectively. Moreover, multi-group confirmatory factor analysis was performed to determine the invariance of the Farsi and English versions of the VSM 08. The perceptive learning style was found to have a significant negative relationship with the power distance and monumentalism indices of the VSM 08. Moreover, a significant negative association was observed between the solitary learning style and the power distance index. However, no significant association was found between the analytic, competitive, and imaginative learning styles and cultural values (P>0.05). Likewise, no significant associations were observed between learning style, including the perceptive, solitary, analytic, competitive, and imaginative learning styles, and year of study or age (P>0.05). Students who reported low values on the power distance and monumentalism indices are more likely to prefer perceptive and solitary learning styles. Within each group of students in our study sample from the same school the year of study and age did not show any significant associations with learning style.

Proximity effect bilayer nano superconducting quantum interference devices for millikelvin magnetometry

Energy Technology Data Exchange (ETDEWEB)

Blois, A., E-mail: a.blois@ucl.ac.uk; Rozhko, S.; Romans, E. J. [London Centre for Nanotechnology, University College London (UCL), 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Hao, L.; Gallop, J. C. [National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW (United Kingdom)

2013-12-21

Superconducting quantum interference devices (SQUIDs) incorporating thin film nanobridges as weak links have sensitivities approaching that required for single spin detection at 4.2 K. However, due to thermal hysteresis they are difficult to operate at much lower temperatures which hinder their application to many quantum measurements. To overcome this, we have developed nanoscale SQUIDs made from titanium-gold proximity bilayers. We show that their electrical properties are consistent with a theoretical model developed for heat flow in bilayers and demonstrate that they enable magnetic measurements to be made on a sample at system temperatures down to 60 mK.

Preparation and studies of Co(II) and Co(III)-substituted barium ferrite prepared by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Teh, Geok Bee [Department of Bioscience and Chemistry, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, 53300 Kuala Lumpur (Malaysia)]. E-mail: tehgb@mail.utar.edu.my; Nagalingam, Saravanan [Department of Bioscience and Chemistry, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, 53300 Kuala Lumpur (Malaysia); Jefferson, David A. [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

2007-01-15

The sol-gel preparative method was employed to synthesise Co(II) and Co(III)-substituted barium ferrite. This method was attempted to achieve higher homogeneity of the final product. Samples of substituted ferrites were characterised by various experimental techniques including high resolution transmission electron microscopy, X-ray diffraction analysis, magnetometry and thermal gravimetric analysis. The microstructural changes induced by such substitution are also discussed.

Preparation and studies of Co(II) and Co(III)-substituted barium ferrite prepared by sol-gel method

International Nuclear Information System (INIS)

Teh, Geok Bee; Nagalingam, Saravanan; Jefferson, David A.

2007-01-01

The sol-gel preparative method was employed to synthesise Co(II) and Co(III)-substituted barium ferrite. This method was attempted to achieve higher homogeneity of the final product. Samples of substituted ferrites were characterised by various experimental techniques including high resolution transmission electron microscopy, X-ray diffraction analysis, magnetometry and thermal gravimetric analysis. The microstructural changes induced by such substitution are also discussed

Porphyrin-based magnetic nanocomposites for efficient extraction of polycyclic aromatic hydrocarbons from water samples.

Science.gov (United States)

Yu, Jing; Zhu, Shukui; Pang, Liling; Chen, Pin; Zhu, Gang-Tian

2018-03-09

Stable and reusable porphyrin-based magnetic nanocomposites were successfully synthesized for efficient extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. Meso-Tetra (4-carboxyphenyl) porphyrin (TCPP), a kind of porphyrin, can connect the copolymer after amidation and was linked to Fe 3 O 4 @SiO 2 magnetic nanospheres via cross-coupling. Several characteristic techniques such as field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, vibrating sample magnetometry and a tensiometer were used to characterize the as-synthesized materials. The structure of the copolymer was similar to that of graphene, possessing sp 2 -conjugated carbon rings, but with an appropriate amount of delocalized π-electrons giving rise to the higher extraction efficiency for heavy PAHs without sacrificing the performance in the extraction of light PAHs. Six extraction parameters, including the TCPP:Fe 3 O 4 @SiO 2 (m:m) ratio, the amount of adsorbents, the type of desorption solvent, the desorption solvent volume, the adsorption time and the desorption time, were investigated. After the optimization of extraction conditions, a comparison of the extraction efficiency of Fe 3 O 4 @SiO 2 -TCPP and Fe 3 O 4 @SiO 2 @GO was carried out. The adsorption mechanism of TCPP to PAHs was studied by first-principles density functional theory (DFT) calculations. Combining experimental and calculated results, it was shown that the π-π stacking interaction was the main adsorption mechanism of TCPP for PAHs and that the amount of delocalized π-electrons plays an important role in the elution process. Under the optimal conditions, Fe 3 O 4 @SiO 2 -porphyrin showed good precision in intra-day (<8.9%) and inter-day (<13.0%) detection, low method detection limits (2-10 ng L -1 ), and wide linearity (10-10000 ng L -1 ). The method was applied to simultaneous analysis of 15 PAHs with

Tailoring of Perpendicular Magnetic Anisotropy in Dy13Fe87 Thin Films with Hexagonal Antidot Lattice Nanostructure

Directory of Open Access Journals (Sweden)

Mohamed Salaheldeen

2018-04-01

Full Text Available In this article, the magnetic properties of hexagonally ordered antidot arrays made of Dy13Fe87 alloy are studied and compared with corresponding ones of continuous thin films with the same compositions and thicknesses, varying between 20 nm and 50 nm. Both samples, the continuous thin films and antidot arrays, were prepared by high vacuum e-beam evaporation of the alloy on the top-surface of glass and hexagonally self-ordered nanoporous alumina templates, which serve as substrates, respectively. By using a highly sensitive magneto-optical Kerr effect (MOKE and vibrating sample magnetometer (VSM measurements an interesting phenomenon has been observed, consisting in the easy magnetization axis transfer from a purely in-plane (INP magnetic anisotropy to out-of-plane (OOP magnetization. For the 30 nm film thickness we have measured the volume hysteresis loops by VSM with the easy magnetization axis lying along the OOP direction. Using magnetic force microscopy measurements (MFM, there is strong evidence to suggest that the formation of magnetic domains with OOP magnetization occurs in this sample. This phenomenon can be of high interest for the development of novel magnetic and magneto-optic perpendicular recording patterned media based on template-assisted deposition techniques.

Magnetic characterization by SQUID and FMR of a biocompatible ferrofluid based on Fe3O4

International Nuclear Information System (INIS)

Gamarra, L F; Amaro Jr, E; Pontuschka, W M; Mamani, J B; Cornejo, D R; Oliveira, T R; Vieira, E D; Costa-Filho, A J

2009-01-01

Biocompatible superparamagnetic iron oxide nanoparticles of magnetite coated with dextran were magnetically characterized using the techniques of SQUID (superconducting quantum interference device) magnetometry and ferromagnetic resonance (FMR). The SQUID magnetometry characterization was performed by isothermal measurements under applied magnetic field using the methods of zero-field-cooling (ZFC) and field-cooling (FC). The magnetic behavior of the nanoparticles indicated their superparamagnetic nature and it was assumed that they consisted exclusively of monodomains. The transition to a blocked state was observed at the temperature T B = (43 ± 1) K for frozen ferrofluid and at (52 ± 1) K for the lyophilized ferrofluid samples. The FMR analysis showed that the derivative peak-to-peak linewidth (ΔH PP ), gyromagnetic factor (g), number of spins (N S ), and spin-spin relaxation time (T 2 ) were strongly dependent on both temperature and super-exchange interaction. This information is important for possible nanotechnological applications, mainly those which are strongly dependent on the magnetic parameters.

Scaling analysis of [Fe(pyrazole){sub 4}]{sub 2}[Nb(CN){sub 8}] molecular magnet

Energy Technology Data Exchange (ETDEWEB)

Konieczny, P., E-mail: piotr.konieczny@ifj.edu.pl [Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków (Poland); Pełka, R.; Zieliński, P.M. [Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków (Poland); Pratt, F.L. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX (United Kingdom); Pinkowicz, D.; Sieklucka, B. [Department of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Wasiutyński, T. [Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków (Poland)

2013-10-15

The critical behaviour of the three dimensional (3D) molecular magnet {[Fe"I"I(pirazol)_4]_2[Nb"I"V(CN)_8]·4H_2O}{sub n} has been studied with the use of experimental techniques such as ac magnetometry and zero field μSR spectroscopy. The sample orders magnetically below T{sub c}=7.8 K. The measurements allowed to determine static exponents β, γ, and the dynamic exponent w. The resulting exponent values indicate that the studied system belongs to the universality class of the 3D Heisenberg model. - Highlights: • The critical behaviour of {[Fe"I"I(pirazol)_4]_2[Nb"I"V(CN)_8]∙4H_2O}{sub n} has been studied. • Critical exponents β, γ, and w were obtained from ac magnetometry and ZF µSR data. • All obtained values of critical exponents are close to the 3D Heisenberg model.

Investigation of Structural, Morphological, Magnetic Properties and Biomedical applications of Cu2+ Substituted Uncoated Cobalt Ferrite Nanoparticles

Directory of Open Access Journals (Sweden)

M. Margabandhu

Full Text Available ABSTRACT In the present work, Cu2+ substituted cobalt ferrite (Co1-xCuxFe2O4, x = 0, 0.3, 0.5, 0.7 and 1 magnetic nanopowders were synthesized via chemical co-precipitation method. The prepared powders were investigated by various characterization methods such as X-ray diffraction analysis (XRD, scanning electron microscope analysis (SEM, vibrating sample magnetometer analysis (VSM and fourier transform infrared spectroscopy analysis (FTIR. The XRD analysis reveals that the synthesized nanopowders possess single phase centred cubic spinel structure. The average crystallite size of the particles ranging from 27-49 nm was calculated by using Debye-scherrer formula. Magnetic properties of the synthesized magnetic nanoparticles are studied by using VSM. The VSM results shows the magnetic properties such as coercivity, magnetic retentivity decreases with increase in copper substitution whereas the saturation magnetization shows increment and decrement in accordance with Cu2+ substitution in cobalt ferrite nanoparticles. SEM analysis reveals the morphology of synthesized magnetic nanoparticles. FTIR spectra of Cu2+ substituted cobalt ferrite magnetic nanoparticles were recorded in the frequency range 4000-400cm-1. The spectrum shows the presence of water adsorption and metal oxygen bonds. The adhesion nature of Cu2+ substituted cobalt ferrite magnetic nanoparticles with bacteria in reviewed results indicates that the synthesized nanoparticles could be used in biotechnology and biomedical applications.

Enhanced room temperature ferromagnetism in Cr-doped ZnO nanoparticles prepared by auto-combustion method

Science.gov (United States)

Haq, Khizar-ul; Irfan, M.; Masood, Muhammad; Saleem, Murtaza; Iqbal, Tahir; Ahmad, Ishaq; Khan, M. A.; Zaffar, M.; Irfan, Muhammad

2018-04-01

Zn1‑x Cr x O (x = 0.00, 0.01, 0.03, 0.05, 0.07, and 0.09) nanoparticles were synthesized, by an auto-combustion method. Structural, optical, and magnetic characteristics of Cr-doped ZnO samples calcined at 600 °C have been analyzed by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), UV–Vis spectroscopy and vibrating sample magnetometer (VSM). The XRD data confirmed the hexagonal wurtzite structure of pure and Cr-doped ZnO nanoparticles. The calculated values of grain size using Scherrer's formula are in the range of 30.7–9.2 nm. The morphology of nanopowders has been observed by FESEM, and EDS results confirmed a systematic increase of Cr content in the samples and clearly indicate with no impurity element. The band gaps, computed by UV–Vis spectroscopy, are in the range of 2.83–2.35 eV for different doping concentrations. By analyzing VSM data, significantly enhanced room temperature ferromagnetism is identified in Cr-doped ZnO samples. The value of magnetization is a 12 times increased of the value reported by Daunet al. (2010). Room temperature ferromagnetism of the nanoparticles is of vital prominence for spintronics applications. Project supported by the Office of Research, Innovation, and Commercialization (ORIC), MUST Mirpur (AJK).

Effect of Zn and Ni substitution on structural, morphological and magnetic properties of tin oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Bhuvana, S. [Research and Development Centre, Bharathiar University, Coimbatore 641046, Tamilnadu (India); Department of Physics, Dr. NGP Institute of Technology, Coimbatore 641048, Tamilnadu (India); Ramalingam, H.B.; Vadivel, K. [Department of Physics, Government Arts College, Udumalpet 642126, Tamilnadu (India); Ranjith Kumar, E., E-mail: ranjueaswar@gmail.com [Department of Physics, Dr. NGP Institute of Technology, Coimbatore 641048, Tamilnadu (India); Ayesh, Ahmad I. [Department of Math., Stat. and Physics, Qatar University, Doha (Qatar)

2016-12-01

Structural, morphological, optical and magnetic properties of Zn and Zn–Ni co-doped tin oxide (SnO{sub 2}) nanoparticles synthesized by sol-gel method. The influence of doping concentration on phase and particle size of the nanoparticles was determined by X-ray diffraction. The XRD study reveals that the lattice constant and crystallite size of the samples decrease with the increase of doping concentration. The change in the band gap energy of SnO{sub 2} nanoparticles influenced more by doping with Zn and Ni. The external morphology and particle size were recorded by SEM and TEM. The results indicated that Ni{sup 2+} ions would uniformly substituted into the Zn{sup 2+} sites of SnO{sub 2} lattice. The substitution of Ni creates a vital change in magnetic properties that has been measured by vibrating sample magnetometer (VSM). - Highlights: • Sn{sub 2-(x+y)} Ni{sub x}Zn{sub y}O{sub 2}, (x=y=0.07 to 0.10) nano particles are prepared by simple sol gel method. • X-ray diffraction data confirms the single phase rutile tetragonal structure. • The VSM was used to confirm, the codoping of (Ni, Zn) increases the magnetic moment of the sample prepared. • Inducing ferromagnetism in sample makes it suitable for future spintronics applications.

Preparation and magnetic properties of polymer magnetic composites based on acrylate resin filled with nickel plating graphite nanosheets

Energy Technology Data Exchange (ETDEWEB)

Zhang Yi, E-mail: zhangyi520love@yahoo.com.cn [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Qi Shuhua; Zhang Fan; Yang Yongqing; Duan Guochen [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China)

2011-11-01

Nickel plating graphite nanosheets (Ni/GNs) were prepared by electroless plating method using graphite nanosheets (GNs). Then a novel polymer magnetic composites based on acrylate pressure-sensitive adhesive (acrylate PSA) filled with Ni/GNs were fabricated by solution blend method. The Ni/GNs and acrylate PSA/Ni/GNs composites were characterized by scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscope (TEM). All results showed that relatively uniform and compact Ni layer is successfully coated onto GNs under the given conditions, furthermore, Ni/GNs are homogeneously dispersed in acrylate PSA. The VSM results showed that the saturation magnetization of acrylate PSA/Ni/GNs composites increases with an increasing content of Ni/GNs while the coercivity decreases with an increasing content of Ni/GNs. When the content of GNs is 20 wt%, acrylate PSA/Ni/GNs composites exhibites good mechanical properties.

Preparation and magnetic properties of polymer magnetic composites based on acrylate resin filled with nickel plating graphite nanosheets

International Nuclear Information System (INIS)

Zhang Yi; Qi Shuhua; Zhang Fan; Yang Yongqing; Duan Guochen

2011-01-01

Nickel plating graphite nanosheets (Ni/GNs) were prepared by electroless plating method using graphite nanosheets (GNs). Then a novel polymer magnetic composites based on acrylate pressure-sensitive adhesive (acrylate PSA) filled with Ni/GNs were fabricated by solution blend method. The Ni/GNs and acrylate PSA/Ni/GNs composites were characterized by scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscope (TEM). All results showed that relatively uniform and compact Ni layer is successfully coated onto GNs under the given conditions, furthermore, Ni/GNs are homogeneously dispersed in acrylate PSA. The VSM results showed that the saturation magnetization of acrylate PSA/Ni/GNs composites increases with an increasing content of Ni/GNs while the coercivity decreases with an increasing content of Ni/GNs. When the content of GNs is 20 wt%, acrylate PSA/Ni/GNs composites exhibites good mechanical properties.

Value stream mapping as a tool for systematic employee based improvement of the psychosocial work environment in hospitals

DEFF Research Database (Denmark)

Hasle, Peter; Starheim, Liv; Jensen, Per Langaa

2016-01-01

Problems in communication and coordination in hospitals often hamper operations and constitute important stress factor for the staff. A specific methodology (P-lean) based on value stream mapping (VSM) has been developed and tested in practice. Key processes with a potential for psychosocial strain...... are selected and analysed in employee groups. VSM is followed up by collection of data and development of solutions. Results from the practical test show that VSM and process data provide new insights to the employees which help to improve the psychosocial work environment. However, working across departmental...

Molten salts activated by high-energy milling: A useful, low-temperature route for the synthesis of multiferroic compounds

Energy Technology Data Exchange (ETDEWEB)

Hernández-Ramírez, Anayantzin; Martínez-Luévanos, Antonia [Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, V. Carranza s/n, Saltillo, Coahuila 25280 (Mexico); Fuentes, Antonio F. [CINVESTAV Unidad Saltillo, Apdo. Postal 663, Saltillo, Coahuila 25000 (Mexico); Earth and Environmental Science, University of Michigan, 3514 C.C. Little Building, 1100 N. University Avenue, Ann Arbor, MI 48109-1005 (United States); Nelson, Anna-Gay D.; Ewing, Rodney C. [Earth and Environmental Science, University of Michigan, 3514 C.C. Little Building, 1100 N. University Avenue, Ann Arbor, MI 48109-1005 (United States); Montemayor, Sagrario M., E-mail: smmontemayor@gmail.com [Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, V. Carranza s/n, Saltillo, Coahuila 25280 (Mexico); Earth and Environmental Science, University of Michigan, 3514 C.C. Little Building, 1100 N. University Avenue, Ann Arbor, MI 48109-1005 (United States)

2014-01-25

Highlights: • The synthesis route purposed demonstrates the formation of BiFeO{sub 3} at only 500 °C. • The magnetic and ferroelectric properties are comparable to those of bulk BiFeO{sub 3}. • By this route, several phases in Bi{sub 1−x}La{sub x}FeO{sub 3} system are obtained at only 500 °C. • The route developed here could be useful to synthesize other perovskite-type oxides. -- Abstract: There are only a few multiferroic compounds, among which BiFeO{sub 3} is the most important. Research the synthesis of bismuth ferrite, with novel and improved magnetic and electrical properties, has been mainly based on the use of hydrothermal or sol gel methods. However, these methods require either rather extreme conditions or several steps for synthesis. We demonstrate that the use of molten salts, activated by high energy milling, results in pure nanometric BiFeO{sub 3}, LaFeO{sub 3} and intermediate phases in the Bi{sub 1−x}La{sub x}FeO{sub 3} system. The chemical reagents used are Bi(NO{sub 3}){sub 3}⋅5H{sub 2}O, La(NO{sub 3}){sub 3}⋅6H{sub 2}O, Fe(NO{sub 3}){sub 3}⋅9H{sub 2}O and NaOH. A brief milling process of the reagents creates an amorphous precursor and crystalline NaNO{sub 3}. The thermal treatment of the precursors, at 500 °C for two hours, produces a crystalline mixture of Bi{sub 1−x}La{sub x}FeO{sub 3} and NaNO{sub 3}. Simple washing eliminates the NaNO{sub 3}. The characterization of intermediates and final products, through thermal analysis, X-ray diffraction and scanning electronic microscopy, allows the inference of possible mechanism. In addition, vibrating sample magnetometry (VSM) and ferroelectric tests show the typical magnetic and electric polarization loops characteristic of these materials even when formed at the nano-scale.

Synthesis, characterization, and cytotoxicity of the plasmid EGFP-p53 loaded on pullulan–spermine magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Eslaminejad, Touba, E-mail: tslaminejad@yahoo.com [Pharmaceutics Research Centre, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman (Iran, Islamic Republic of); Nematollahi-Mahani, Seyed Noureddin, E-mail: nnematollahi@kmu.ac.ir [Department of Anatomy, Afzalipour School of Medicine, Kerman University of Medical Sciences, Kerman (Iran, Islamic Republic of); Neuroscience Research Centre, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman (Iran, Islamic Republic of); Afzal Research Institute, Kerman (Iran, Islamic Republic of); Ansari, Mehdi, E-mail: mansari@kmu.ac.ir [Pharmaceutics Research Centre, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman (Iran, Islamic Republic of); Pharmaceutics Research Centre, Faculty of Pharmacy, Kerman University of Medical Sciences, Kerman (Iran, Islamic Republic of)

2016-03-15

Magnetic nanoparticles have been used as effective vehicles for the targeted delivery of therapeutic agents that can be controlled in their concentration and distribution to a desired part of the body by using externally driven magnets. This study focuses on the synthesis, characterization, and functionalization of pullulan–spermine (PS) magnetic nanoparticles for medical applications. Magnetite nanopowder was produced by thermal decomposition of goethite (FeOOH) in oleic acid and 1-octadecene; pullulan–spermine was deposited on the magnetite nanoparticles in the form of pullulan–spermine clusters. EGFP-p53 plasmid was loaded on functionalized iron oleate to transfer into cells. Synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), vibrating sample magnetometry (VSM), and transmission electron microscopy (TEM). The encapsulation efficiency and drug loading efficiency of the nanocomplexes were tested. FTIR studies showed the presence of oleic acid and 1-octadecene in the iron oleate nanopowder and verified the interaction between spermine and pullulan. The characteristic bands of PS in the spectrum of the pullulan–spermine-coated iron oleate (PSCFO) confirmed that PS covered the surface of the iron oleate particles. TEM studies showed the average size of the iron oleate nanopowder, the PSCFO, and the plasmid-carrying PSCFO (PSCFO/pEGFP-p53) to be 34±12 nm, 100±50 nm and 172±3 nm, respectively. Magnetic measurements revealed that magnetic saturation of the PSCFO was lower in comparison with the iron oleate nanopowder due to the presence of organic compounds in the former. In cytotoxicity tests performed using U87 cells as glioblastoma cells, a 92% survival rate was observed at 50 µg/µl of the plasmid-carrying PSCFO, with an IC{sub 50} value of 189 µg/µl. - Highlights: • Magnetite nanopowder was produced by thermal decomposition method. • TEM studies showed the average size of

Preparation and characterization of magnetic CsH{sub 2}PW{sub 12}O{sub 40}/Fe–SiO{sub 2} nanocatalysts for biodiesel production

Energy Technology Data Exchange (ETDEWEB)

Feyzi, Mostafa, E-mail: Dalahoo2011@yahoo.com [Faculty of Chemistry, Razi University, P. O. Box: 6714967346, Kermanshah (Iran, Islamic Republic of); Nanoscience and Nanotechnology Research Center (NNRC), Razi University, P. O. Box: 6714967346, Kermanshah (Iran, Islamic Republic of); Nourozi, Leila [Faculty of Chemistry, Razi University, P. O. Box: 6714967346, Kermanshah (Iran, Islamic Republic of); Zakarianezhad, Mohammad [Department of Chemistry, Payam Noor University, Tehran (Iran, Islamic Republic of)

2014-12-15

Graphical abstract: In this study, a series of magnetic CsH{sub 2}PW{sub 12}O{sub 40}/Fe–SiO{sub 2} nanocatalysts were prepared and tested for biodiesel production. The best operational conditions were CH3OH/oil = 12/1 at 60 °C with mechanical stirring, the biodiesel yield reaches to 81% in 4 h. Also notably, recovery of the catalyst can be achieved easily with the help of an external magnet with no need for expensive ultracentrifugation. - Highlights: • Effects of preparation conditions for biodiesel production were studied. • The CsH{sub 2}PW{sub 12}O{sub 40}/Fe–SiO{sub 2} catalyst is efficient catalyst for biodiesel production. • The reaction conditions were found methanol/oil = 12/1, T = 60 °C. - Abstract: The magnetic CsH{sub 2}PW{sub 12}O{sub 40}/Fe–SiO{sub 2} nanocatalysts were prepared via combination of sol–gel and impregnation methods. The effects of different H{sub 3}PW{sub 12}O{sub 40}/(Fe–SiO{sub 2}) weight percentage, loading of Cs as a promotor and calcination conditions on the catalytic performance has been studied. It was found that the catalyst with H{sub 3}PW{sub 12}O{sub 40}/Fe–SiO{sub 2} = 4 wt.% and Cs = 2 wt.% is an optimal catalyst for biodiesel production. The activity of optimal catalyst was studied in different operational conditions. The best operational conditions were CH{sub 3}OH/oil = 12/1 at 60 °C with mechanical stirring rate of 500 rpm and the biodiesel yield reaches to 81% in 4 h. Characterization of catalysts was carried out by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM), N{sub 2} adsorption–desorption measurements methods, Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC)

Synthesis, characterization, and cytotoxicity of the plasmid EGFP-p53 loaded on pullulan–spermine magnetic nanoparticles

International Nuclear Information System (INIS)

Eslaminejad, Touba; Nematollahi-Mahani, Seyed Noureddin; Ansari, Mehdi

2016-01-01

Magnetic nanoparticles have been used as effective vehicles for the targeted delivery of therapeutic agents that can be controlled in their concentration and distribution to a desired part of the body by using externally driven magnets. This study focuses on the synthesis, characterization, and functionalization of pullulan–spermine (PS) magnetic nanoparticles for medical applications. Magnetite nanopowder was produced by thermal decomposition of goethite (FeOOH) in oleic acid and 1-octadecene; pullulan–spermine was deposited on the magnetite nanoparticles in the form of pullulan–spermine clusters. EGFP-p53 plasmid was loaded on functionalized iron oleate to transfer into cells. Synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), vibrating sample magnetometry (VSM), and transmission electron microscopy (TEM). The encapsulation efficiency and drug loading efficiency of the nanocomplexes were tested. FTIR studies showed the presence of oleic acid and 1-octadecene in the iron oleate nanopowder and verified the interaction between spermine and pullulan. The characteristic bands of PS in the spectrum of the pullulan–spermine-coated iron oleate (PSCFO) confirmed that PS covered the surface of the iron oleate particles. TEM studies showed the average size of the iron oleate nanopowder, the PSCFO, and the plasmid-carrying PSCFO (PSCFO/pEGFP-p53) to be 34±12 nm, 100±50 nm and 172±3 nm, respectively. Magnetic measurements revealed that magnetic saturation of the PSCFO was lower in comparison with the iron oleate nanopowder due to the presence of organic compounds in the former. In cytotoxicity tests performed using U87 cells as glioblastoma cells, a 92% survival rate was observed at 50 µg/µl of the plasmid-carrying PSCFO, with an IC 50 value of 189 µg/µl. - Highlights: • Magnetite nanopowder was produced by thermal decomposition method. • TEM studies showed the average size of the

Accuracy of magnetic resonance based susceptibility measurements

Science.gov (United States)

Erdevig, Hannah E.; Russek, Stephen E.; Carnicka, Slavka; Stupic, Karl F.; Keenan, Kathryn E.

2017-05-01

Magnetic Resonance Imaging (MRI) is increasingly used to map the magnetic susceptibility of tissue to identify cerebral microbleeds associated with traumatic brain injury and pathological iron deposits associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease. Accurate measurements of susceptibility are important for determining oxygen and iron content in blood vessels and brain tissue for use in noninvasive clinical diagnosis and treatment assessments. Induced magnetic fields with amplitude on the order of 100 nT, can be detected using MRI phase images. The induced field distributions can then be inverted to obtain quantitative susceptibility maps. The focus of this research was to determine the accuracy of MRI-based susceptibility measurements using simple phantom geometries and to compare the susceptibility measurements with magnetometry measurements where SI-traceable standards are available. The susceptibilities of paramagnetic salt solutions in cylindrical containers were measured as a function of orientation relative to the static MRI field. The observed induced fields as a function of orientation of the cylinder were in good agreement with simple models. The MRI susceptibility measurements were compared with SQUID magnetometry using NIST-traceable standards. MRI can accurately measure relative magnetic susceptibilities while SQUID magnetometry measures absolute magnetic susceptibility. Given the accuracy of moment measurements of tissue mimicking samples, and the need to look at small differences in tissue properties, the use of existing NIST standard reference materials to calibrate MRI reference structures is problematic and better reference materials are required.

Factors facilitating and inhibiting value stream mapping processes at hospital units in three Nordic countries - a Nordic multicenter study

DEFF Research Database (Denmark)

Winkel, Jørgen; Birgisdóttir, Birna Dröfn; Dudas, Kerstin

2014-01-01

The aim of this paper is to present observations that may indicate facilitating and inhibiting factors for the VSM process.......The aim of this paper is to present observations that may indicate facilitating and inhibiting factors for the VSM process....

Structural elucidation and magnetic behavior evaluation of Cu-Cr doped BaCo-X hexagonal ferrites

Science.gov (United States)

Azhar Khan, Muhammad; Hussain, Farhat; Rashid, Muhammad; Mahmood, Asif; Ramay, Shahid M.; Majeed, Abdul

2018-04-01

Ba2-xCuxCo2CryFe28-yO46 (x = 0.0, 0.1, 0.2, 0.3, 0.4, y = 0.0, 0.2, 0.4, 0.6, 0.8) X-type hexagonal ferrites were synthesized via micro-emulsion route. The techniques which were applied to characterize the prepared samples are as follows: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Dielectric measurements and vibrating sample magnetometer (VSM). The structural parameters i.e. lattice constant (a, c), cell volume (V), X-ray density, bulk density and crystallite size of all the prepared samples were obtained using XRD analysis. The lattice parameters 'a' and 'c' increase from 5.875 Å to 5.934 Å and 83.367 Å to 83.990 Å respectively. The crystallite size of investigated samples lies in the range of 28-32 nm. The magnetic properties of all samples have been calculated by vibrating sample magnetometer (VSM) analysis. The increase in coercivity (Hc) was observed with the increase of doping contents. It was observed that the coercivity (Hc) of all prepared samples is inversely related to the crystalline size which reflects that all materials are super-paramagnetic. The dielectric parameters i.e. dielectric constant, dielectric loss, tangent loss etc were obtained in the frequency range of 1 MHz-3 GHz and followed the Maxwell-Wagner's model. The significant variation the dielectric parameters are observed with increasing frequency. The maximum Q value is obtained at ∼2 GHz due to which these materials are used for high frequency multilayer chip inductors.

Magnetic Properties of (Nia-ZnbX Cu1-X Ferrite Nanoparticle Fabricated by Sol-Gel Process

Directory of Open Access Journals (Sweden)

Yang S.

2017-06-01

Full Text Available In future, more mobile devices with different frequencies will be used at the same time. Therefore, it is expected that the trouble caused by wave interference between devices will be further intensified. In order to prevent this trouble, investigation of selective frequency transmission or absorption material is required. In this paper, magnetic properties of nickel-zinc-copper ferrite nano powder was researched as wave absorber. (Nia-ZnbxCu1-xFe2O4(NZCF nanoparticles were fabricated by the sol-gel method. The influence of copper substitution on lattice parameter change was analyzed by X-ray diffraction (XRD, particle size was analyzed by scanning electron microscopy (SEM, and Magnetic properties analyzed by vibrating sample magnetometer (VSM. The NZCF and Nickel-zinc ferrite (NZF lattice parameter difference was 0.028 Å and particle size was calculated as 30 nm with the XRD peak. The VSM results of (Ni0.3-Zn0.30.6Cu1-0.6Fe2O4 annealed sample at 700°C for 3hous were 58.5 emu/g (Ms, 22.8 Oe (Hc. It was the most suitable magnetic properties for wave absorber in this investigation.

Structural and magnetic properties of hcp and fcc Ni nanoparticles

International Nuclear Information System (INIS)

Gong, J.; Wang, L.L.; Liu, Y.; Yang, J.H.; Zong, Z.G.

2008-01-01

The face-centered-cubic (fcc) and hexagonal-close-packed (hcp) Ni nanoparticles were synthesized with citrate by sol-gel method and heat-treating technique. The structure, morphology and magnetic properties of the samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). Our XRD and TEM results suggested that hcp Ni nanoparticles were successfully synthesized when the heating temperature reaches 300 deg. C. With a further increase in temperature to 400 deg. C, a temperature-induced phase transformation of hcp to fcc was observed. Moreover, the VSM results demonstrated the existence of ferromagnetic behavior in the synthesized fcc and hcp Ni nanoparticles. Nevertheless, the magnetic measurement suggested that the magnetic properties in hcp nanoparticles is probably the sum of two contributions: superparamagnetic and ferromagnetic one. The unsaturated magnetization is much smaller than 47.6 emu/g for the fcc nanoparticles obtained at 400 deg. C and 55 emu/g for the bulk material. It was also found that changes of the stress, grain size and crystal structure during heat-treating have significant influences on the magnetic properties of the Ni nanoparticles

Ergonomic Value Stream Mapping – Can lean and ergonomics go hand in hand?

DEFF Research Database (Denmark)

Edwards, Kasper

2014-01-01

This paper reports findings from an orthopedic bed ward where ErgoVSM has been used as part of a lean project.......This paper reports findings from an orthopedic bed ward where ErgoVSM has been used as part of a lean project....

Anomalous kinetics of lath martensite formation in stainless steel

DEFF Research Database (Denmark)

Villa, Matteo; Hansen, Mikkel Fougt; Pantleon, Karen

2015-01-01

The kinetics of lath martensite formation in Fe-17.3 wt-%Cr-7.1 wt-%Ni-1.1 wt-%Al-0.08 wt-%C stainless steel was investigated with magnetometry and microscopy. Lath martensite forms during cooling, heating and isothermally. For the first time, it is shown by magnetometry during extremely slow...

Long-range magnetostatic interactions in arrays of nanowires

CERN Document Server

Raposo, V; González, J M; Vázquez, M

2000-01-01

Experimental measurements and micromagnetic simulations of the hysteresis loops of arrays of cobalt nanowires are compared here. Arrays of cobalt nanowires (200 nm in diameter) were electrodeposited into the pores of alumina membranes (thickness 60 mu m). Their hysteresis loops along the axial direction of nanowires were measured using vibrating sample magnetometry. Micromagnetic simulations were performed considering dipolar interaction between nanowires leading to similar hysteresis loops as those obtained experimentally.

Nano semiconducting materials

CERN Document Server

Saravanan, R

2016-01-01

The main focus of the present book is the characterization of a number of nano-semiconducting materials, using such techniques as powder X-ray diffraction, UV-visible spectrophotometry, Raman spectrometry, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. The materials studied include ZnS, TiO2, NiO, Ga doped ZnO, Mn doped SnO2, Mn doped CeO2 and Mn doped ZrO2.

Martensitbildung in Fe-basierten Legierungen während der Erwärmung von Stickstoff-Siedetemperatur

DEFF Research Database (Denmark)

Villa, Matteo; Christiansen, Thomas Lundin; Hansen, Mikkel Fougt

2016-01-01

The austenite-to-martensite transformation at temperatures below room temperature was investigated in situ by magnetometry in Fe-N, Fe-Cr-C and Fe-Cr-Ni based alloys. After quenching to room temperature, samples were immersed in boiling nitrogen and martensite formation was followed during...... subsequent heating to room temperature. Different tests were performed with heating rates ranging from 0.5 K/min to 10 K/min. For comparison a sample was up-quenched in water to verify whether martensite formation can be suppressed at high heating rates. Thermally activated formation of martensite during...

The genetic and environmental structure of verbal and visuospatial memory in young adults and children

NARCIS (Netherlands)

van Leeuwen, Marieke; van den Berg, Stéphanie Martine; Hoekstra, Rosa A.; Boomsma, Dorret I.

2009-01-01

The extent to which verbal (VM) and visuospatial memory (VSM) tests measure the same or multiple constructs is unclear. Likewise the relationship between VM and VSM across development is not known. These questions are addressed using genetically informative data, studying two age cohorts (young

The Genetic and Environmental Structure of Verbal and Visuospatial Memory in Young Adults and Children

NARCIS (Netherlands)

van Leeuwen, M.; van den Berg, S.M.; Hoekstra, R.A.; Boomsma, D.I.

2009-01-01

The extent to which verbal (VM) and visuospatial memory (VSM) tests measure the same or multiple constructs is unclear. Likewise the relationship between VM and VSM across development is not known. These questions are addressed using genetically informative data, studying two age cohorts (young

Facilitating and inhibiting factors in change processes based on the lean tool ‘value stream mapping’: an exploratory case study at hospital wards

DEFF Research Database (Denmark)

Winkel, Jørgen; Edwards, Kasper; Birgisdóttir, Birna Dröfn

2015-01-01

‘Lean production’ has become a prevalent rationalisation methodology in healthcare. Value stream mapping (VSM) is a commonly used lean tool to identify non-value-adding-work. VSM is a participatory tool. Thus, it may offer an opportunity to combine interventions for improved performance...

Global issues in volatile substance misuse.

Science.gov (United States)

Dell, Colleen Anne; Gust, Steven W; MacLean, Sarah

2011-01-01

This special issue of Substance Use & Misuse addresses the public health issue of volatile substance misuse (VSM), the inhalation of gases or vapors for psychoactive effects, assessing the similarities and differences in the products misused, patterns, prevalence, etiologies, and impacts of VSM by examining it through sociocultural epidemiology, neuroscience, and interventions research. The Canadian, US, and Australian guest editors contend that, when compared with other drugs used at a similar prevalence, VSM has attracted relatively little research effort. The authors and editors call for further research to develop evidence-based policies and comprehensive interventions that respect culture and context-specific knowledge.

Six easy steps on how to create a lean sigma value stream map for a multidisciplinary clinical operation.

Science.gov (United States)

Lee, Emily; Grooms, Richard; Mamidala, Soumya; Nagy, Paul

2014-12-01

Value stream mapping (VSM) is a very useful technique to visualize and quantify the complex workflows often seen in clinical environments. VSM brings together multidisciplinary teams to identify parts of processes, collect data, and develop interventional ideas. An example involving pediatric MRI with general anesthesia VSM is outlined. As the process progresses, the map shows a large delay between the fax referral and the date of the scheduled and registered appointment. Ideas for improved efficiency and metrics were identified to measure improvement within a 6-month period, and an intervention package was developed for the department. Copyright © 2014. Published by Elsevier Inc.

Synthesis of magnetic mesoporous metal-organic framework-5 for the effective enrichment of malachite green and crystal violet in fish samples.

Science.gov (United States)

Zhou, Zhihui; Fu, Yanqing; Qin, Qian; Lu, Xin; Shi, Xianzhe; Zhao, Chunxia; Xu, Guowang

2018-07-27

A novel, magnetic and mesoporous Fe 3 O 4 @PEI-MOF-5 material was synthesized for the effective enrichment of malachite green (MG) and crystal violet (CV) in fish samples. The Fe 3 O 4 @PEI-MOF-5 material was prepared by a facile two-step solvothermal approach in which Fe 3 O 4 @PEI and MOF-5 were connected through chemical bonds. Characterization of the newly synthesized Fe 3 O 4 @PEI-MOF-5 material was performed by Fourier transform infrared spectroscopy, X-ray diffractometry, vibrating sample magnetometry, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. This new material was determined to have high magnetization and chemical stability, a large surface area and a distinctive morphology. An effective enrichment and detection method for MG and CV was subsequently developed by combining the Fe 3 O 4 @PEI-MOF-5 material with ultra-high-performance liquid chromatography-tandem mass spectrometry. The linearity ranges of this approach for MG and CV were 1-500ng/mL and 0.25-500ng/mL, respectively, with correlation coefficients (R 2 ) of 0.999. The limits of detection (LODs) of the method for MG and CV were 0.30ng/mL and 0.08ng/mL, respectively, indicating that the Fe 3 O 4 @PEI-MOF-5 material had good adsorption properties for MG and CV. Fe 3 O 4 @PEI-MOF-5 can be expected to also provide efficient enrichment of MG and CV in other complex matrices. Copyright © 2018 Elsevier B.V. All rights reserved.

Co-treatment of fruit and vegetable waste in sludge digesters. An analysis of the relationship among bio-methane generation, process stability and digestate phytotoxicity.

Science.gov (United States)

Di Maria, Francesco; Sordi, Alessio; Cirulli, Giuseppe; Gigliotti, Giovanni; Massaccesi, Luisa; Cucina, Mirko

2014-09-01

The co-digestion of a variable amount of fruit and vegetable waste in a waste mixed sludge digester was investigated using a pilot scale apparatus. The organic loading rate (OLR) was increased from 1.46 kg VS/m(3) day to 2.8 kg VS/m(3) day. The hydraulic retention time was reduced from 14 days to about 10 days. Specific bio-methane production increased from about 90 NL/kg VS to the maximum value of about 430 NL/kg VS when OLR was increased from 1.46 kg VS/m(3) day to 2.1 kg VS/m(3) day. A higher OLR caused an excessive reduction in the hydraulic retention time, enhancing microorganism wash out. Process stability evaluated by the total volatile fatty acids concentration (mg/l) to the alkalinity buffer capacity (eq. mg/l CaCO3) ratio (i.e. FOS/TAC) criterion was 2.46 kg VS/m(3) day, GI decreased rapidly. This corresponding trend between FOS/TAC and GI was further investigated by the definition of the GI ratio (GIR) parameter. Comparison between GIR and FOS/TAC suggests that GI could be a suitable criterion for evaluating process stability. Copyright © 2014 Elsevier Ltd. All rights reserved.

Video self-modeling as a post-treatment fluency recovery strategy for adults.

Science.gov (United States)

Harasym, Jessica; Langevin, Marilyn; Kully, Deborah

2015-06-01

This multiple-baseline across subjects study investigated the effectiveness of video self-modeling (VSM) in reducing stuttering and bringing about improvements in associated self-report measures. Participants' viewing practices and perceptions of the utility of VSM also were explored. Three adult males who had previously completed speech restructuring treatment viewed VSM recordings twice per week for 6 weeks. Weekly speech data, treatment viewing logs, and pre- and post-treatment self-report measures were obtained. An exit interview also was conducted. Two participants showed a decreasing trend in stuttering frequency. All participants appeared to engage in fewer avoidance behaviors and had less expectations to stutter. All participants perceived that, in different ways, the VSM treatment had benefited them and all participants had unique viewing practices. Given the increasing availability and ease in using portable audio-visual technology, VSM appears to offer an economical and clinically useful tool for clients who are motivated to use the technology to recover fluency. Readers will be able to describe: (a) the tenets of video-self modeling; (b) the main components of video-self modeling as a fluency recovery treatment as used in this study; and (c) speech and self-report outcomes. Copyright © 2015 Elsevier Inc. All rights reserved.

A comparative study of NiZn ferrites modified by the addition of cobalt

Directory of Open Access Journals (Sweden)

Pereira S.L.

1999-01-01

Full Text Available Off-stoichiometric NiZn ferrite was obtained by hydrothermal process and compacted in torus form under different pressures. Two samples A1 and A2 - cobalt doped (0.5 % were sintered at 1573 K in air atmosphere during 3 h. The magnetic properties were studied by vibrating sample magnetometry, Mössbauer spectroscopy and complex impedanciometry. X-ray diffraction and Hg porosimetry were used in order to determine the average grain size and the type of packing in the samples. Both samples exhibited superparamagnetic behavior in the hysteresis loop. This effect does not agree with Mössbauer results, which were fitted using Normos, a commercial computer program. All samples parameters were compared.

Associations of learning style with cultural values and demographics in nursing students in Iran and Malaysia

Directory of Open Access Journals (Sweden)

Abdolghani Abdollahimohammad

2015-08-01

Full Text Available Purpose: The goal of the current study was to identify associations between the learning style of nursing students and their cultural values and demographic characteristics. Methods: A non-probability purposive sampling method was used to gather data from two populations. All 156 participants were female, Muslim, and full-time degree students. Data were collected from April to June 2010 using two reliable and validated questionnaires: the Learning Style Scales and the Values Survey Module 2008 (VSM 08. A simple linear regression was run for each predictor before conducting multiple linear regression analysis. The forward selection method was used for variable selection. P-values ≤0.05 and ≤0.1 were considered to indicate significance and marginal significance, respectively. Moreover, multi-group confirmatory factor analysis was performed to determine the invariance of the Farsi and English versions of the VSM 08. Results: The perceptive learning style was found to have a significant negative relationship with the power distance and monumentalism indices of the VSM 08. Moreover, a significant negative association was observed between the solitary learning style and the power distance index. However, no significant association was found between the analytic, competitive, and imaginative learning styles and cultural values (P>0.05. Likewise, no significant associations were observed between learning style, including the perceptive, solitary, analytic, competitive, and imaginative learning styles, and year of study or age (P>0.05. Conclusion: Students who reported low values on the power distance and monumentalism indices are more likely to prefer perceptive and solitary learning styles. Within each group of students in our study sample from the same school the year of study and age did not show any significant associations with learning style.

Phase transformation and magnetic anisotropy of an iron-palladium ferromagnetic shape-memory alloy

International Nuclear Information System (INIS)

Cui, J.; Shield, T.W.; James, R.D.

2004-01-01

Martensitic phase transformations in an Fe 7 Pd 3 alloy were studied using various experimental techniques: visual observation, differential scanning calorimeter (DSC) measurements and X-ray diffraction. Magnetic measurements on this alloy were made using a vibrating sample magnetometer (VSM) and a Susceptibility Kappa bridge. The VSM measurements were made with the sample in a compression fixture to bias the martensite phase to a single variant. Both X-ray and DSC measurements show that the FCC-FCT transformation is a weak first-order thermoelastic transition. The average lattice parameters are a=3.822±0.001 A and c=3.630±0.001 A for the FCT martensite, and a 0 =3.756±0.001 A for the FCC austenite. The latent heat of the FCC-FCT transformation is 10.79±0.01 J/cm 3 . A Susceptibility Kappa bridge measurement determined the Curie temperature to be 450 deg. C. The saturation magnetization from VSM data is m s =1220±10 emu/cm 3 at -20 deg. C for the martensite and m s =1080±10 emu/cm 3 at 60 deg. C for the austenite. The easy axes of a single variant of FCT martensite are the [1 0 0] and [0 1 0] directions (the a-axes of the FCT lattice) and the [0 0 1] direction (FCT c-axis) is the hard direction. The cubic magnetic anisotropy constant K 1 is -5±2x10 3 erg/cm 3 for the austenite at 60 deg. C, and the tetragonal anisotropy constant K 1 +K 2 is 3.41 ± 0.02 x 10 5 erg/cm 3 for the martensite at a temperature of -20 deg. C and under 8 MPa of compressive stress in the [0 0 1] direction

Synthesis and characterization of nanocrystalline ZnWO4-ZnO composites and their humidity sensing performance

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M.V. Arularasu

2016-12-01

Full Text Available We investigate the experimental results on the composites ZnWO4-ZnO for electrical and humidity sensing properties are described. ZnWO4 (ZW prepared by precipitation method and this prepared zinc tungstate mixed with ZnO (ZO in different mole rations (100:0, 80:20, 60:40, 40:60, 20:80, 0:100. The products were characterized in detail by multi techniques: X-ray diffraction (XRD, energy dispersive X-ray analysis (EDX, field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, Brunauer-Emmett-Teller (BET analysis and vibrating sample magnetometer (VSM. The composites were sintered in the form of the disc and subjected to dc resistance measurements. The dc resistance of these composites decreased on exposure to humidity at room temperature. These results demonstrate composite ZWZO-46 has the highest humidity sensitivity Sf = 3416, with a response and recovery time of 50 s and 100 s respectively. Keywords: Composites, Relative humidity, Humidity sensor, VSM, Hysteresis

Study of the magnetic anisotropy in Ni/Cu and Ni/glass thin films

International Nuclear Information System (INIS)

Cherif, S.-M.; Layadi, A.; Ben Youssef, J.; Nacereddine, C.; Roussigne, Y.

2007-01-01

The magnetic properties of evaporated Ni/Cu and Ni/glass thin films have been investigated by means of the vibrating sample magnetometer (VSM), the Brillouin light scattering (BLS) and magnetic force microscopy (MFM). The Ni thickness, t, ranges from 31 to 165 nm. The second- and fourth-order magnetic anisotropy constants, K 1 and K 2 , have been included; for the Ni/Cu series, K 1 was found to decrease from 1.0x10 6 to 0.18x10 6 erg/cm 3 as t increases from 31 to 165 nm, while K 2 increased from 0.24x10 6 to 0.8x10 6 erg/cm 3 . Over all the thickness range, the magnetization easy axis is in plane. For thinner films, there is a good agreement between anisotropy constant values inferred from VSM and BLS. Stripe domains were observed for t≥165 nm in Ni/glass and t≥90 nm in Ni/Cu

The synthesis of a new kind of magnetic coating on carbon fibers by electrodeposition

Energy Technology Data Exchange (ETDEWEB)

Wang Rui; Wan Yizao; He Fang; Qi Yu; You Wei [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Luo Honglin, E-mail: hlluo64@yahoo.com [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

2012-01-15

Nickel/Fe{sub 3}O{sub 4} nanoparticle (Ni/Fe{sub 3}O{sub 4}-NPs) composite coatings on the surface of carbon fiber were prepared by electrodeposition in a nickel-plating bath containing Fe{sub 3}O{sub 4} nanoparticles (Fe{sub 3}O{sub 4}-NPs). The composite of carbon fiber with nanocomposite coatings were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) analysis, thermogravimetric (TG) analysis and vibrating sample magnetometer (VSM). The microstructure observation reveals that the Fe{sub 3}O{sub 4}-NPs distribute uniformly in the coatings. TG and VSM analysis show that the carbon fibers with Ni/Fe{sub 3}O{sub 4}-NPs composite coatings exhibit higher thermal stability and saturation magnetization than carbon fiber with Ni coatings. The result is attributed to the homogeneous distribution of magnetic Fe{sub 3}O{sub 4} in the composite coatings.

Effects of Video Self-Modeling on Eliminating Public Undressing by Elementary-Aged Students with Developmental Disabilities during Urination

Science.gov (United States)

Ohtake, Yoshihisa; Takeuchi, Ai; Watanabe, Kentaro

2014-01-01

This study investigated the effectiveness of video self-modeling (VSM) for eliminating the public undressing of two elementary-aged students with developmental disabilities during urination. A multiple-probe design across participants revealed that the degree of exposed body parts decreased immediately after introduction of VSM. However, exposure…

Video Self-Modeling: A Promising Strategy for Noncompliant Children.

Science.gov (United States)

Axelrod, Michael I; Bellini, Scott; Markoff, Kimberly

2014-07-01

The current study investigated the effects of a Video Self-Modeling (VSM) intervention on the compliance and aggressive behavior of three children placed in a psychiatric hospital. Each participant viewed brief video clips of himself following simple adult instructions just prior to the school's morning session and the unit's afternoon free period. A multiple baseline design across settings was used to evaluate the effects of the VSM intervention on compliance with staff instructions and aggressive behavior on the hospital unit and in the hospital-based classroom. All three participants exhibited higher levels of compliance and fewer aggressive episodes during the intervention condition, and the effects were generally maintained when the intervention was withdrawn. Hospital staff reported at the conclusion of the study that the VSM intervention was easy to implement and beneficial for all participants. Taken altogether, the results suggest VSM is a promising, socially acceptable, and proactive intervention approach for improving the behavior of noncompliant children. © The Author(s) 2014.

Apelin-13 inhibits large-conductance Ca2+-activated K+ channels in cerebral artery smooth muscle cells via a PI3-kinase dependent mechanism.

Directory of Open Access Journals (Sweden)

Amit Modgil

Full Text Available Apelin-13 causes vasoconstriction by acting directly on APJ receptors in vascular smooth muscle (VSM cells; however, the ionic mechanisms underlying this action at the cellular level remain unclear. Large-conductance Ca(2+-activated K(+ (BKCa channels in VSM cells are critical regulators of membrane potential and vascular tone. In the present study, we examined the effect of apelin-13 on BK(Ca channel activity in VSM cells, freshly isolated from rat middle cerebral arteries. In whole-cell patch clamp mode, apelin-13 (0.001-1 μM caused concentration-dependent inhibition of BK(Ca in VSM cells. Apelin-13 (0.1 µM significantly decreased BK(Ca current density from 71.25 ± 8.14 pA/pF to 44.52 ± 7.10 pA/pF (n=14 cells, P<0.05. This inhibitory effect of apelin-13 was confirmed by single channel recording in cell-attached patches, in which extracellular application of apelin-13 (0.1 µM decreased the open-state probability (NPo of BK(Ca channels in freshly isolated VSM cells. However, in inside-out patches, extracellular application of apelin-13 (0.1 µM did not alter the NPo of BK(Ca channels, suggesting that the inhibitory effect of apelin-13 on BKCa is not mediated by a direct action on BK(Ca. In whole cell patches, pretreatment of VSM cells with LY-294002, a PI3-kinase inhibitor, markedly attenuated the apelin-13-induced decrease in BK(Ca current density. In addition, treatment of arteries with apelin-13 (0.1 µM significantly increased the ratio of phosphorylated-Akt/total Akt, indicating that apelin-13 significantly increases PI3-kinase activity. Taken together, the data suggest that apelin-13 inhibits BK(Ca channel via a PI3-kinase-dependent signaling pathway in cerebral artery VSM cells, which may contribute to its regulatory action in the control of vascular tone.

Protein Kinase C Inhibitors as Modulators of Vascular Function and Their Application in Vascular Disease

Directory of Open Access Journals (Sweden)

Raouf A. Khalil

2013-03-01

Full Text Available Blood pressure (BP is regulated by multiple neuronal, hormonal, renal and vascular control mechanisms. Changes in signaling mechanisms in the endothelium, vascular smooth muscle (VSM and extracellular matrix cause alterations in vascular tone and blood vessel remodeling and may lead to persistent increases in vascular resistance and hypertension (HTN. In VSM, activation of surface receptors by vasoconstrictor stimuli causes an increase in intracellular free Ca2+ concentration ([Ca2+]i, which forms a complex with calmodulin, activates myosin light chain (MLC kinase and leads to MLC phosphorylation, actin-myosin interaction and VSM contraction. Vasoconstrictor agonists could also increase the production of diacylglycerol which activates protein kinase C (PKC. PKC is a family of Ca2+-dependent and Ca2+-independent isozymes that have different distributions in various blood vessels, and undergo translocation from the cytosol to the plasma membrane, cytoskeleton or the nucleus during cell activation. In VSM, PKC translocation to the cell surface may trigger a cascade of biochemical events leading to activation of mitogen-activated protein kinase (MAPK and MAPK kinase (MEK, a pathway that ultimately increases the myofilament force sensitivity to [Ca2+]i, and enhances actin-myosin interaction and VSM contraction. PKC translocation to the nucleus may induce transactivation of various genes and promote VSM growth and proliferation. PKC could also affect endothelium-derived relaxing and contracting factors as well as matrix metalloproteinases (MMPs in the extracellular matrix further affecting vascular reactivity and remodeling. In addition to vasoactive factors, reactive oxygen species, inflammatory cytokines and other metabolic factors could affect PKC activity. Increased PKC expression and activity have been observed in vascular disease and in certain forms of experimental and human HTN. Targeting of vascular PKC using PKC inhibitors may function in

Systematic study on surface and magnetostructural changes in Mn-substituted dysprosium ferrite by hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Rekha, G. [Department of Physics, College of Engineering Guindy, Anna University, Sardar Patel Road, Chennai 600025 (India); Tholkappiyan, R. [Department of Physics, College of Engineering Guindy, Anna University, Sardar Patel Road, Chennai 600025 (India); Department of Physics, College of Science, UAE University, Al-Ain 15551 (United Arab Emirates); Vishista, K., E-mail: raovishista@gmail.com [Department of Physics, College of Engineering Guindy, Anna University, Sardar Patel Road, Chennai 600025 (India); Hamed, Fathalla [Department of Physics, College of Science, UAE University, Al-Ain 15551 (United Arab Emirates)

2016-11-01

Highlights: • Garnet type Dy{sub 3}Fe{sub 5-x}Mn{sub x}O{sub 12} (x = 0–0.06) nanoparticles of 88.4–86.8 nm were synthesized by hydrothermal method. • The Dy, Mn, Fe and O elements in the ferrites were confirmed from XPS. • The multiple oxidation states of Fe and Mn ions, bonding energy and cationic distributions of the samples were examined by XPS. • The magnetic property shows ferromagnetic behavior from VSM technique. • The results from these studies are correlated with respect to Mn dopant. - Abstract: Dysprosium iron garnets are of scientific importance because of the wide range of magnetic properties that can be obtained in substituting dysprosium by a rare earth metal. In the present work, the effect of Mn substitution on magnetostructural changes in dysprosium ferrite nanoparticles is studied. Highly crystalline pure and Mn doped dysprosium ferrite nanoparticles were synthesized by hydrothermal method. The samples were calcined at 1100 °C for 2 h in air atmosphere which is followed by characterization using XRD, FT-IR analysis, SEM, XPS and VSM. The average crystallite size of synthesized samples were calculated by X-ray diffraction falls in the range of 88.4–86.8 nm and was found to be in cubic garnet structure. For further investigation of the structure and corresponding changes in the tetrahedral and octahedral stretching vibrational bonds, FT-IR was used. The synthesized samples consist of multiple oxidation (Fe{sup 3+} and Fe{sup 2+}) states for Fe ions and (Mn{sup 3+} and Mn{sup 2+}) Mn ions analyzed in three ways of Fe 2p and Mn 2p spectra from the XPS analysis. With respect to Mn dopant in Dy{sub 3}Fe{sub 5}O{sub 12}, the cationic distributions of elements were discussed from high resolution XPS spectra by peak position and shift, area, width. To find out the porous/void surface morphology of the sample, scanning electron microscopy was used. From XPS analysis, the presence of elements (Dy, Mn, Fe and O) and their composition in the

Structural and magnetic properties of cadmium substituted manganese ferrites prepared by hydrothermal route

Energy Technology Data Exchange (ETDEWEB)

Mostafa, Nasser Y., E-mail: nmost69@yahoo.com [Faculty of Science, Taif University, P.O. Box: 888, Al-Haweiah, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt); Zaki, Z.I. [Faculty of Science, Taif University, P.O. Box: 888, Al-Haweiah, Taif (Saudi Arabia); Advanced Materials Division, Central Metallurgical R and D Institute (CMRDI), P.O. Box: 87 Helwan, Cairo (Egypt); Heiba, Z.K. [Faculty of Science, Taif University, P.O. Box: 888, Al-Haweiah, Taif (Saudi Arabia); Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt)

2013-03-15

Cd-substituted manganese ferrite Mn{sub 1-x}Cd{sub x}Fe{sub 2}O{sub 4} powders with x having values 0.0, 0.1, 0.3 and 0.5 have been synthesized by hydrothermal route at 180 Degree-Sign C in presence of NaOH as mineralizer. The obtained ferrite samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The XRD analysis showed that pure single phases of cubic ferrites were obtained with x upto 0.3. However, sample with x{>=}0.5 showed hexagonal phase of cadmium hydroxide (Cd(OH){sub 2}) besides the ferrite phase. The increase in Cd-substitution upto x=0.3 leads to an increase in the lattice parameter as well as the average crystallite size of the prepared ferrites. The average crystallite size increased by increasing the Cd-content and was in the range of 39-57 nm. According to VSM results, the saturation magnetization increased with Cd ion substitution. - Highlights: Black-Right-Pointing-Pointer Hydrothermal synthesized of mono dispersed Cd-substituted MnFe{sub 2}O{sub 4} nanoparticles. Black-Right-Pointing-Pointer The change in Ms with increasing Cd-substitution was investigated Black-Right-Pointing-Pointer Pure single phases of cubic ferrites were obtained with x up to 0.3 Black-Right-Pointing-Pointer Sample with x{>=}0.5 showed hexagonal phase of Cd(OH){sub 2} beside the ferrite.

Isothermal martensite formation at sub-zero temperatures

DEFF Research Database (Denmark)

Stojko, Allan; Hansen, Mikkel Fougt; Slycke, Jan

2012-01-01

, quenched in oil, and thereafter investigated with vibrating sample magnetometry, which allows a quantitative assessment of the fraction of retained austenite as a function of the sub-zero temperature and time. Isothermal martensite formation was observed on interrupting the continuous cooling (5 K...... with a continuation of the martensitic transformation. On prolonged isothermal holding, a volume reduction was observed for AISI 52100, but not for AISI 1070. Copyright © 2011 by ASTM International....

Mechanism of kolaviron-induced relaxation of rabbit aortic smooth ...

African Journals Online (AJOL)

(KV) and the exert mechanisms of action on VSM of rabbit aorta have not been reported. The present study examines the vascular effect of kolaviron on VSM of rabbit aorta and the possible mechanism of its vasorelaxant effect. MATERIALS AND METHODS. Extraction of Kolaviron (KV). Garcinia Kola seeds were obtained ...

Effect of strontium deficiency on the transport and magnetic properties of Pr{sub 0.7}Sr{sub 0.3}MnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Abou-Ras, D.; Boujelben, W.; Cheikh-Rouhou, A.; Pierre, J.; Renard, J.-P. E-mail: jean-pierre.renard@ief.u-psud.fr; Reversat, L.; Shimizu, K

2001-08-01

Ceramic samples of Pr{sub 0.7}Sr{sub 0.3-x}{open_square}{sub x}MnO{sub 3} with x{<=}0.2 have been investigated by various techniques including {sup 55}Mn nuclear magnetic resonance, SQUID magnetometry, resistivity and magnetoresistance measurements. On increasing x, the samples remain ferromagnetic at a low temperature with a decreasing Curie temperature, but a metal-insulator transition is observed. Besides, a positive magnetoresistance (MR) at very low temperatures with respect to a negative colossal MR at high temperatures is observed in the Pr{sub 0.7}Sr{sub 0.2}{open_square}{sub 0.1}MnO{sub 3} sample.

Simulation guided value stream mapping and lean improvement: A case study of a tubular machining facility

Directory of Open Access Journals (Sweden)

Wei Xia

2013-06-01

Full Text Available Purpose: This paper describes a typical Value stream mapping (VSM application enhanced by the discrete event simulation (DES to a dedicated tubular manufacturing process. Design/Methodology/Approach: VSM is prescribed as part of lean production portfolio of tools, not only highlights process inefficiencies, transactional and communication mismatches, but also guides improvement areas. Meanwhile, DES is used to reduce uncertainty and create consensus by visualizing dynamic process views. It is served as a complementary tool for the traditional VSM to provide sufficient justification and quantifiable evidence needed to convince the lean approaches. A simulation model is developed to replicate the operation of an existing system, and that of a proposed system that modifies the existing design to incorporate lean manufacturing shop floor principles. Findings: A comprehensive model for the tubular manufacturing process is constructed, and distinctive scenarios are derived to uncover an optimal future state of the process. Various simulation scenarios are developed. The simulated results are acquired and investigated, and they are well matched with the real production data. Originality/Value: DES is demonstrated as a guided tool to assist organizations with the decision to implement lean approaches by quantifying benefits from applying the VSM. A roadmap is provided to illustrate how the VSM is used to design a desired future state. The developed simulation scenarios mimic the behavior of the actual manufacturing process in an intuitive manner.

Intrinsic magnetic properties of hexagonal LuFeO3 and the effects of nonstoichiometry

Directory of Open Access Journals (Sweden)

Jarrett A. Moyer

2014-01-01

Full Text Available We used oxide molecular-beam epitaxy in a composition-spread geometry to deposit hexagonal LuFeO3 (h-LuFeO3 thin films with a monotonic variation in the Lu/Fe cation ratio, creating a mosaic of samples that ranged from iron rich to lutetium rich. We characterized the effects of composition variation with x-ray diffraction, atomic force microscopy, scanning transmission electron microscopy, and superconducting quantum interference device magnetometry. After identifying growth conditions leading to stoichiometric film growth, an additional sample was grown with a rotating sample stage. From this stoichiometric sample, we determined stoichiometric h-LuFeO3 to have a TN = 147 K and Ms = 0.018 μB/Fe.

Interplay of structural chemistry and magnetism in perovskites; A study of CaLn2Ni2WO9; Ln=La, Pr, Nd

Science.gov (United States)

Chin, Chun-Mann; Paria Sena, Robert; Hunter, Emily C.; Hadermann, Joke; Battle, Peter D.

2017-07-01

Polycrystalline samples of CaLn2Ni2WO9 (Ln=La, Pr, Nd) have been synthesized and characterised by a combination of X-ray and neutron diffraction, electron microscopy and magnetometry. Each composition adopts a perovskite-like structure with a 5.50, b 5.56, c 7.78 Å, β 90.1° in space group P21/n. Of the two crystallographically distinct six-coordinate sites, one is occupied entirely (Ln=Pr) or predominantly (Ln=La, Nd) by Ni2+ and the other by Ni2+ and W6+ in a ratio of approximately 1:2. None of the compounds shows long-range magnetic order at 5 K. The magnetometry data show that the magnetic moments of the Ni2+ cations form a spin glass below 30 K in each case. The Pr3+ moments in CaPr2Ni2WO9 also freeze but the Nd3+ moments in CaNd2Ni2WO9 do not. This behaviour is contrasted with that observed in other (A,A')B2B'O9 perovskites.

A quantitative study of particle size effects in the magnetorelaxometry of magnetic nanoparticles using atomic magnetometry

Energy Technology Data Exchange (ETDEWEB)

Dolgovskiy, V. [Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland); Lebedev, V., E-mail: victor.lebedev@unifr.ch [Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland); Colombo, S.; Weis, A. [Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland); Michen, B.; Ackermann-Hirschi, L. [Adolphe Merkle Institute, University of Fribourg, CH-1700 Fribourg (Switzerland); Petri-Fink, A. [Adolphe Merkle Institute, University of Fribourg, CH-1700 Fribourg (Switzerland); Chemistry Department, University of Fribourg, CH-1700 Fribourg (Switzerland)

2015-04-01

The discrimination of immobilised superparamagnetic iron oxide nanoparticles (SPIONs) against SPIONs in fluid environments via their magnetic relaxation behaviour is a powerful tool for bio-medical imaging. Here we demonstrate that a gradiometer of laser-pumped atomic magnetometers can be used to record accurate time series of the relaxing magnetic field produced by pre-polarised SPIONs. We have investigated dry in vitro maghemite nanoparticle samples with different size distributions (average radii ranging from 14 to 21 nm) and analysed their relaxation using the Néel–Brown formalism. Fitting our model function to the magnetorelaxation (MRX) data allows us to extract the anisotropy constant K and the saturation magnetisation M{sub S} of each sample. While the latter was found not to depend on the particle size, we observe that K is inversely proportional to the (time- and size-) averaged volume of the magnetised particle fraction. We have identified the range of SPION sizes that are best suited for MRX detection considering our specific experimental conditions and sample preparation technique. - Highlights: • We studied magnetorelaxation of magnetic nanoparticles using atomic magnetometers. • We show that atomic magnetometers yield high precision MRX data. • The observed magnetorelaxation is well described by the moment superposition model. • Model fits allow extraction of nanoparticle material parameters of six samples. • All samples exhibit an unexpected size-dependent anisotropy constant.

Attenuation of salt-induced hypertension by aqueous calyx extract of ...

African Journals Online (AJOL)

olayemitoyin

which ultimately spreads to the vascular smooth muscle (VSM) producing a fall in VSM intracellular calcium leading to vasodilatation (Amberg et al.,. 2003; Haddy, Vanhoutte and Feletou, 2006) and a fall in blood pressure. The higher heart rate of salt loaded rats compared to control rats (Fig. 3) is suggestive of sympathetic.

Structural, magnetic and electrical properties of nickel doped Mn-Zn spinel ferrite synthesized by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Jalaiah, K., E-mail: kjalu4u@gmail.com [Department of Physics, Andhra University, Visakhapatnam 530003 (India); Vijaya Babu, K. [Advanced Analytical Laboratory, Andhra University, Visakhapatnam 530003 (India)

2017-02-01

Manganese ferrites (MnFe{sub 2}O{sub 4}) have been of great interest for their remarkable and soft-magnetic properties (low coercivity, moderate saturation magnetization) accompanied by good chemical stability and mechanical hardness. X-ray diffraction analysis confirmed the presence of single phase cubic spinel ferrite with space group Fm3m for all prepared samples. Structural parameters such as lattice constant, crystallite size were calculated from the studies of X-ray diffraction. The morphological analysis of all the compounds is studied using scanning electron microscope. The magnetic properties were measured using electron spin resonance (ESR) and vibrating sample magnetometer (VSM). The results obtained showed the formation of manganese ferrites with an average particle size are in good agreement with previous results and displayed good magnetic properties. The dielectric and impedance properties are studied over a frequency range 20 Hz–1 MHz at room temperature. - Highlights: • We prepared Mn{sub 0.85}Zn{sub 0.15}Ni{sub x}Fe{sub 2}O{sub 4} (x=0.03, 0.06, 0.09, 0.12 and 0.15) nano-ferrite materials by using sol-gel method. • All the compounds characterized by XRD, SEM, VSM, ESR and dielectric studies. • We get lower coercivity values. • We get good results from ESR spectra.

Value stream mapping and simulation for implementation of lean manufacturing practices in a footwear company

Directory of Open Access Journals (Sweden)

Danilo Felipe Silva de Lima

2016-03-01

Full Text Available The development of the Value Stream Mapping (VSM is generally the first step for implementation of Lean Manufacturing (LM. The aim of this paper is to present an application of VSM with simulation in order to analyze the impacts of the LM adoption in the performance of a footwear plant. Therefore, a VSM was designed for the current state and, through the implementation of lean elements, a future state could be designed. Different scenarios were simulated for the future state implementation and the results were compared each other. Transfer, cutting and assembly sections were chosen to be simulated, because it was considered that would be possible to establish a one-piece flow between those processes. After the simulation, the scenario that presented the best results provided a 19% productivity increase over the current state, as well as improvement in all other process variables. The application of simulation as an additional element of VSM has helped to identify the advantages of the joint approach, since it enables to test different alternatives and better define the future state and its implementation strategies.

Video Self-Modelling: An Intervention for Children with Behavioural Difficulties

Science.gov (United States)

Regan, Helen; Howe, Julia

2017-01-01

There has recently been a growth in interest in the use of video technology in the practice of educational psychologists. This research explores the effects of a video self-modelling (VSM) intervention on the behaviours of a child in mainstream education using a single case study design set within a behaviourist paradigm. VSM is a behavioural…

Effect of synthesis conditions on the photocatalytic property of multiferroic BiFeO{sub 3} towards the degradation of phenol red

Energy Technology Data Exchange (ETDEWEB)

Dhanalakshmi, Radhalayam; Muneeswaran, M.; Giridharan, N. V., E-mail: giri@nitt.edu [Advanced Functional Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli-620 015 (India)

2016-05-23

Multiferroic BiFeO{sub 3} has been synthesized through hydrothermal route under different reaction conditions. From the basic characterization such as of X-Ray diffraction analysis (XRD), the synthesized Nps were found to having rhombohedral structure with R3c space group. Photodegradation studies of toxic dye phenol red have been investigated under visible light irradiation. Vibrating sample magnetometer (VSM) analysis has been carried out to identify the magnetic properties and recycle ability photocatalysts.

Magnetic properties of high temperature superconductors and their interaction with high energy permanent magnets

International Nuclear Information System (INIS)

Agarwala, A.K.

1990-01-01

Magnetic properties of sintered samples of YBCO ceramic superconductors at various temperatures were measured using a vibrating sample magnetometer (VSM). Also, measurements of forces experienced by a well characterized rare earth-transition metal (RE-TM) permanent magnet (PM) interacting with the superconducting YBCO sample cooled in liquid nitrogen, were performed. Based upon the observed hysteretic magnetization properties of these high temperature superconductors (HTS), the HTS-PM interaction force at liquid nitrogen temperature was calculated from first principle, and finally correlated to the force measurement results. With this analysis, magnetic forces between the same HTS and PM system including the levitation as well as suspension effects at liquid-helium temperature are predicted

Investigation of the annealing temperature effect on structural, morphology, dielectric and magnetic properties of BiFeO3 nanoparticles

Science.gov (United States)

Ranjbar, M.; Ghazi, M. E.; Izadifard, M.

2018-06-01

In this paper we have investigated the annealing temperature effect on the structure, morphology, dielectric and magnetic properties of sol-gel synthesized multiferroic BiFeO3 nanoparticles. X-ray diffraction spectroscopy revealed that all the samples have rhombohedrally distorted perovskite structure and the most pure BFO phase is obtained on the sample annealed at 800 °C. Field emission scanning electron microscopy (FESEM) revealed that increasing annealing temperature would increase the particle size. Decrease in dielectric constant was also observed by increasing annealing temperature. Vibrating sample method (VSM) analysis confirmed that samples annealed at 500-700 °C with particle size below the BFO's spiral spin structure length, have well saturated M-H curve and show ferromagnetic behavior.

Ultrasound assisted extraction of Maxilon Red GRL dye from water samples using cobalt ferrite nanoparticles loaded on activated carbon as sorbent: Optimization and modeling.

Science.gov (United States)

Mehrabi, Fatemeh; Vafaei, Azam; Ghaedi, Mehrorang; Ghaedi, Abdol Mohammad; Alipanahpour Dil, Ebrahim; Asfaram, Arash

2017-09-01

In this research, a selective, simple and rapid ultrasound assisted dispersive solid-phase micro-microextraction (UA-DSPME) was developed using cobalt ferrite nanoparticles loaded on activated carbon (CoFe 2 O 4 -NPs-AC) as an efficient sorbent for the preconcentration and determination of Maxilon Red GRL (MR-GRL) dye. The properties of sorbent are characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Vibrating sample magnetometers (VSM), Fourier transform infrared spectroscopy (FTIR), Particle size distribution (PSD) and Scanning Electron Microscope (SEM) techniques. The factors affecting on the determination of MR-GRL dye were investigated and optimized by central composite design (CCD) and artificial neural networks based on genetic algorithm (ANN-GA). CCD and ANN-GA were used for optimization. Using ANN-GA, optimum conditions were set at 6.70, 1.2mg, 5.5min and 174μL for pH, sorbent amount, sonication time and volume of eluent, respectively. Under the optimized conditions obtained from ANN-GA, the method exhibited a linear dynamic range of 30-3000ngmL -1 with a detection limit of 5.70ngmL -1 . The preconcentration factor and enrichment factor were 57.47 and 93.54, respectively with relative standard deviations (RSDs) less than 4.0% (N=6). The interference effect of some ions and dyes was also investigated and the results show a good selectivity for this method. Finally, the method was successfully applied to the preconcentration and determination of Maxilon Red GRL in water and wastewater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigating in vitro bioactivity and magnetic properties of the ferrimagnetic bioactive glass–ceramic fabricated using soda-lime–silica waste glass

Energy Technology Data Exchange (ETDEWEB)

Abbasi, M. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Street, Shiraz (Iran, Islamic Republic of); Hashemi, B., E-mail: hashemib@shirazu.ac.ir [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Street, Shiraz (Iran, Islamic Republic of); Shokrollahi, H. [Electroceramics Group, Materials Science and Engineering Department, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of)

2014-04-01

The main purpose of the current research is the production and characterization of a ferrimagnetic bioactive glass–ceramic prepared through the solid-state reaction method using soda-lime–silica waste glass as the main raw material. In comparison with the conventional route, that is, the melt-quenching and subsequent heat treatment, the present work is an economical technique. Structural, thermal and magnetic properties of the samples were examined by X-ray diffraction (XRD), differential thermal analysis (DTA) and vibrating sample magnetometer (VSM). The in vitro test was utilized to assess the bioactivity level of the samples by Hanks' solution as simulated body fluid (SBF). The apatite surface layer formation was examined by the scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The calcium ion concentration in the solutions was measured by atomic absorption spectroscopy (AAS). VSM results revealed that with the addition of 5–20 wt% strontium hexaferrite to bioactive glass–ceramics, the ferrimagnetic bioactive glass–ceramics with hysteresis losses between 7024 and 75,852 erg/g were obtained. The in vitro test showed that the onset formation time of hydroxyapatite layer on the surface of the samples was 14 days and after 30 days, this layer was completed. - Highlights: • A novel ferrimagnetic bioactive glass–ceramic was synthesized by an incorporation method. • The bioactive part was synthesized by the solid-state reaction method using soda-lime–silica waste glass. • The doping of SrFe{sub 12}O{sub 19} to Bioglass{sup ®} 45S5 glass–ceramic is likely to decrease bioactivity.

Magnetic studies of Fe-Y compositionally modulated thin films

International Nuclear Information System (INIS)

Badia, F.; Ferrater, C.; Lousa, A.; Martinez, B.; Labarta, A.; Tejada, J.

1990-01-01

Compositionally modulated thin films of Y/Fe have been studied by using SQUID magnetometry. Samples were grown by electron-beam evaporation onto Kapton substrates. In the low applied field regime, the samples show irreversible behavior when they are submitted to ZFC-FC magnetization processes, increasing the irreversibility zone as the thickness of the Fe layers increases. In the high applied magnetic field regime (H≥10 000 Oe), samples show ferromagnetic behavior. The temperature dependence of the saturation magnetization has been studied, and it was found that both spin-wave excitations and Stoner excitations occur at temperatures higher than 40 K, and a marked deviation from the T 3/2 law was noted below 30 K

Micro structural and magnetic characterization of Gd doped SnO2 nanoparticles

International Nuclear Information System (INIS)

Adhikari, R.; Das, A.K.; Karmakar, D.; Chandrasekhar Rao, T.V.; Ghatak, J.

2008-01-01

Gd doped SnO 2 nanoparticles were prepared by a chemical co-precipitation method. The prepared samples were calcined at 600 deg C. The annealed samples were characterized using XRD, TEM and SQUID magnetometry. The structural characterizations showed formation of particles in the nanometer regime. The M(T) and M(H) studies indicated an antiferromagnetic (AFM) interaction in 3 and 6% (at. wt.) Gd doped SnO 2 nanoparticles. The M(H) plot of both samples indicate a super paramagnetic (SPM) behavior at 7K as against the perfect AFM nature at 300K. The samples exhibit an insulating DMS nature, but we do not observe any ferromagnetism as was observed for other Gd doped systems like GaN and ZnO. (author)

Characterizations of diverse mole of pure and Ni-doped α-Fe2O3 synthesized nanoparticles through chemical precipitation route.

Science.gov (United States)

Sivakumar, S; Anusuya, D; Khatiwada, Chandra Prasad; Sivasubramanian, J; Venkatesan, A; Soundhirarajan, P

2014-07-15

In the present study, an attempt has been made for characterization and synthesis of pure and Ni-doped α-Fe2O3 (hematite) nanoparticles by chemical precipitation method. The synthesized products have been studied by X-ray diffraction (X-RD), Fourier transform infrared (FTIR) spectroscopy, UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), vibrating sample magnetometer (VSM) and scanning electron microscopy (SEM) techniques. The estimated average diameter of α-Fe2O3 nanoparticles were calculated by using the Debye-Scherrer equation and established as 31 nm. SEM micrographs showed the surface morphology as well as structures and particles distributions of synthesized samples. The UV-Vis DRS showed the indirect and direct band gap energies of pure and Ni-doped α-Fe2O3, these were reduced from 1.9847 to 1.52 eV and 2.0503 to 1.76 eV respectively. This result suggested the dopant enhanced the semiconducting behavior of iron oxide nanoparticles to an extent proportional to its nickel doped in the α-Fe2O3. Further, the magnetic properties of the pure and doped samples were investigated by vibrating sample magnetometer (VSM) and evaluated the information of pure and doped samples exhibited saturated hysteresis loop at room temperature, which is indicating that the weak ferromagnetism in nature of our synthesized samples. In addition, it has been found from the magnetization hysteresis curves of Ni-doping, resulting from increased the saturation of magnetization and reduced the coercivity of used samples. Therefore, the present study showed the reduction in band gap energies and coercive field for α-Fe2O3 nanoparticles due to nickel doped. Copyright © 2014 Elsevier B.V. All rights reserved.

New Initiatives for Synoptic Observations

Indian Academy of Sciences (India)

tribpo

131. Figure 4. The SOLIS mount. 5.2 Vector Spectromagnetograph (VSM). The VSM is a 50 cm quasi RC telescope with an active secondary mirror that com pensates for image motion and telescope shake up to 40 Hz. The telescope is filled with helium to reduce internal seeing by about a factor of 10 and has a 6 mm thick.

A wide-frequency range AC magnetometer to measure the specific absorption rate in nanoparticles for magnetic hyperthermia

International Nuclear Information System (INIS)

Garaio, E.; Collantes, J.M.; Garcia, J.A.; Plazaola, F.; Mornet, S.; Couillaud, F.; Sandre, O.

2014-01-01

Measurement of specific absorption rate (SAR) of magnetic nanoparticles is crucial to assert their potential for magnetic hyperthermia. To perform this task, calorimetric methods are widely used. However, those methods are not very accurate and are difficult to standardize. In this paper, we present AC magnetometry results performed with a lab-made magnetometer that is able to obtain dynamic hysteresis-loops in the AC magnetic field frequency range from 50 kHz to 1 MHz and intensities up to 24 kA m −1 . In this work, SAR values of maghemite nanoparticles dispersed in water are measured by AC magnetometry. The so-obtained values are compared with the SAR measured by calorimetric methods. Both measurements, by calorimetry and magnetometry, are in good agreement. Therefore, the presented AC magnetometer is a suitable way to obtain SAR values of magnetic nanoparticles. - Highlights: • We propose AC magnetometry as a method to measure the specific absorption rate (SAR) of magnetic nanoparticles suitable for magnetic hyperthermia therapy. • We have built a lab-made AC magnetometer, which is able to measure magnetic dynamic hysteresis-loops of nanoparticle dispersions. • The device works with AC magnetic field intensities up to 24 kA m −1 in a frequency range from 75 kHz to 1 MHz. • The SAR values of maghemite nanoparticles around 12 nm in magnetic diameter dispersed in water are measured by the lab-made magnetometer and different calorimetric methods. • Although all methods are in good agreement, several factors (probe location, thermal inertia, losses, etc.) make calorimetric method less accurate than AC magnetometry

Study of the magnetic anisotropy in Ni/Cu and Ni/glass thin films

Energy Technology Data Exchange (ETDEWEB)

Cherif, S.-M. [Laboratoire PMTM, Institut Galilee, Univeriste Paris 13, Villetaneuse, 93340 (France); Layadi, A. [Departement de Physique, Universite Ferhat Abbas, Setif 19000 (Algeria)]. E-mail: a_layadi@yahoo.fr; Ben Youssef, J. [Laboratoire de Magnetisme de Bretagne, U.B.O., Brest 29238 (France); Nacereddine, C. [Departement de Physique, Universite Ferhat Abbas, Setif 19000 (Algeria); Roussigne, Y. [Laboratoire PMTM, Institut Galilee, Univeriste Paris 13, Villetaneuse, 93340 (France)

2007-01-01

The magnetic properties of evaporated Ni/Cu and Ni/glass thin films have been investigated by means of the vibrating sample magnetometer (VSM), the Brillouin light scattering (BLS) and magnetic force microscopy (MFM). The Ni thickness, t, ranges from 31 to 165 nm. The second- and fourth-order magnetic anisotropy constants, K {sub 1} and K {sub 2}, have been included; for the Ni/Cu series, K {sub 1} was found to decrease from 1.0x10{sup 6} to 0.18x10{sup 6} erg/cm{sup 3} as t increases from 31 to 165 nm, while K {sub 2} increased from 0.24x10{sup 6} to 0.8x10{sup 6} erg/cm{sup 3}. Over all the thickness range, the magnetization easy axis is in plane. For thinner films, there is a good agreement between anisotropy constant values inferred from VSM and BLS. Stripe domains were observed for t{>=}165 nm in Ni/glass and t{>=}90 nm in Ni/Cu.

Synthesis and characterization of magnetite nanoparticles having different cover layer and investigation of cover layer effect on the adsorption of lysozyme and bovine serum albumin.

Science.gov (United States)

Shah, Muhammad Tariq; Alveroglu, Esra

2017-12-01

In this study, differently coated superparamagnetic Fe 3 O 4 (magnetite) nanoparticles were synthesized, characterized and used for lysozyme (Ly) and bovine serum albumin (BSA) adsorption. SiO 2 , carbon nanotubes (CNTs) and graphene were used for covering the readily synthesized magnetite nanoparticles to elucidate the effect of cover layer on the protein adsorption kinetics and capacities of nanostructure. XRD, FTIR, AFM, SEM, VSM and fluorescence measurements were used for the characterization of the samples and investigating the adsorption kinetics of Ly and BSA by these nanoparticles. The average particle size of the Fe 3 O 4 nanoparticles are approximately found as 10nm and VSM measurement shows that the Fe 3 O 4 particles have superparamagnetic behavior with no hysteresis and remnant. The adsorption kinetic of proteins on nanosized material is followed via fluorescence method. All the nanostructures with different cover layers obey pseudo first order kinetics and SiO 2 coated nanoparticles show the fastest kinetics and capabilities for Ly and BSA adsorption. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and Characterization of Nano-Crystalline Cu and Pb0.5-Cu0.5- ferrites by Mechanochemical Method and Their Electrical and Gas Sensing Properties

Directory of Open Access Journals (Sweden)

V. B. GAIKWAD

2011-11-01

Full Text Available In the present communication, we have reported the synthesis of nanocrystalline ferrites of the type CuFe2O4 and Pb0.5Cu0.5Fe2O4 by mechanochemical alloying at 960 0C. The samples prepared were characterized by X-ray diffraction (XRD, VSM, FT-IR, UV-DRS, and SEM. The average particle size was determined by XRD pattern using Scherrer equation and it is 7.295 nm, 4.484 nm for CuFe2O4, and Pb0.5Cu0.5Fe2O4. The surface morphology of the samples is characterized by scanning electron microscopy (SEM. Magnetic studies were carried out using vibrating sample magnetometer (VSM and shows very high coercive field for the mixed ferrite. UV-DRS studies were performed to investigate the band gap of synthesized nanocrystalline material. Electrical properties show semiconducting nature of synthesized ferrites. The thick films of the material were prepared by screen printing method. The gas sensing properties were studied towards reducing gases like CO, NH3 and H2S and it was revealed that CuFe2O4 is the most sensitive and selective to H2S gas at relatively lower operating temperature 200 0C. Furthermore Pb0.5Cu0.5Fe2O4 also shows the response to H2S at operating temperature 300 0C.

VALUE STREAM MAPPINGIN THE ROMANIAN FOOTWEAR INDUSTRY

Directory of Open Access Journals (Sweden)

Sorin BRICIU

2015-04-01

Full Text Available Cost reduction, productivity increase and creating value for the client are just a few of the arguments that managers use when they adopt Lean philosophy. Businesses’ concern is to create products that have value in the eyes of the client, continuously analyzing the existing value stream in order to improve it. Value stream mapping (VSM is a technique used to visually present the chain of processes, within the company, necessary to obtain the product. Due to the many advantages and to the ease of use experienced by Toyota since the ’80, VSM use has constantly increased as this activity improvement technique was discovered by managers. The article presents a case study of the application of VSM in footwear industry.

Solution-phase synthesis of single-crystalline Fe3O4 magnetic nanobelts

International Nuclear Information System (INIS)

Li Lili; Chu Ying; Liu Yang; Wang Dan

2009-01-01

Single-crystalline Fe 3 O 4 nanobelt was first synthesized on a large scale by a facile and efficient hydrothermal process. The samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The SAED pattern obtained from a typical individual nanobelt has a highly symmetrical dotted lattice, which reveals the single-crystalline nature of belt-like Fe 3 O 4 . The saturation magnetization of the Fe 3 O 4 nanobelt is higher than the wire, hollow sphere and octahedral structure. Such methods are easy and mild, and could synthesize other metal oxide in such experiment situation

Thermal dependence of coercivity in granular CoNiCu glass coated microwires

International Nuclear Information System (INIS)

Zhukova, V.; Zhukov, A.; Palomares, F.J.; Pigazo, F.; Cebollada, F.; Del Val, J.J.; Garcia, C.; Gonzalez, J.M.; Gonzalez, J.

2007-01-01

Cu 80 Co 19 Ni 1 glass covered microwire samples with different geometric ratio, 0.13≤ρ≤0.5, has been investigated by using X-ray diffraction (XRD) and VSM technique. Our results show (i) the presence of FCC Co crystallites dispersed on the Cu matrix, (ii) the observation in all the samples of the coercivity, at room temperature, of the order of kA, exhibiting a maximum and decreased down to a value of the order of the room temperature one at 25 K. These results are discussed in terms of a distribution of superparamagnetic Co nanoparticles

Sustainable-value stream mapping to evaluate sustainability performance: case study in an Indonesian furniture company

Directory of Open Access Journals (Sweden)

Hartini Sri

2018-01-01

Full Text Available Lean manufacturing tools do not consider environmental and societal benefits. The conventional value stream mapping (VSM methodology examines the economics of a manufacturing line, most of which are in regards to time (cycle time, lead time, change-out time, etc.. Incorporating the capability to capture environmental and societal performance visually through VSMs will increase its usefulness as a tool that can be used to assess manufacturing operations from a sustainability perspective. A number of studies have addressed the extension of VSM to incorporate additional criteria. A vast majority of these efforts have focused on adding energy-related metrics to VSMs, while several other studies refer to ‘sustainable’ VSM by including environmental performance in conventional VSMs. This research has developed a method for VSM integrated with environment metric and social metric for ensuring sustainable manufacture. The proposed technique is capable of visualizing and evaluating manufacturing process performance from sustainability view point. The capability of proposed technique has been tested by an application study on furniture company. The study provides insights to practitioners to visualize process performance in economic, environment and social metric.

Visualization of Environmental Waste by Manufacturing : Equip VSM with Green Perspective

OpenAIRE

Hu, Juebin; Lu, Shan

2011-01-01

This thesis is a subtask of the research project “Green Production System”, which is jointly launched and run by Volvo/Volvo Technology, Haldex, Saab and All-Emballage J.E. AB as industrial party, and Mälardalen University as academic party. The whole project is dedicated to develop “green production system” to be a competitive mean to Swedish automotive and manufacturing industry through four work packages, which are “Wet preconditions and frames of a green production system”, “Visualization...

The enhanced coercivity for the magnetite/silica nanocomposite at room temperature

International Nuclear Information System (INIS)

Wu Mingzai; Xiong Ying; Peng Zhenmeng; Jiang Nan; Qi Haiping; Chen Qianwang

2004-01-01

Magnetite/silica nanocomposite was synthesized by a facile solvothermal processing at 150 deg. C for about 10 h. X-ray diffraction (XRD) analysis revealed the effect of annealing on the crystallinity of silica. Transmission electron microscopy (TEM) images showed the good dispersion of magnetite in the silica matrix. Magnetic properties of the nanocomposite were characterized by vibration sample magnetometer (VSM), and the enhanced coercivity was explained by the intrinsic anisotropy of the particles enhanced by the interparticle dipolar fields

The concept of value stream mapping to reduce of work-time waste as applied the smart construction management

Science.gov (United States)

Elizar, Suripin, Wibowo, Mochamad Agung

2017-11-01

Delays in construction sites occur due to systematic additions of time waste in various activities that are part of the construction process. Work-time waste is non-adding value activity which used to differentiate between physical construction waste found on site and other waste which occurs during the construction process. The aim of this study is identification using the concept of Value Stream Mapping (VSM) to reduce of work-time waste as applied the smart construction management.VSM analysis is a method of business process improvement. The application of VSM began in the manufacturing community. The research method base on theoretically informed case study and literature review. The data have collected using questionnaire through personal interviews from 383 respondents on construction project in Indonesia. The results show that concept of VSM can identify causes of work-time waste. Base on result of questioners and quantitative approach analysis was obtained 29 variables that influence of work-time waste or non-value-adding activities. Base on three cases of construction project founded that average 14.88% of working time was classified as waste. Finally, the concept of VSM can recommend to identification of systematic for reveal current practices and opportunities for improvement towards global challenges. The concept of value stream mapping can help optimize to reduce work-time waste and improve quality standard of construction management. The concept is also can help manager to make a decision to reduce work-time waste so as to obtain of result in more efficient for performance and sustainable construction project.

Effect of magnetic and thermal properties of iron oxide nanoparticles (IONs) in nitrile butadiene rubber (NBR) latex

International Nuclear Information System (INIS)

Ong, Hun Tiar; Julkapli, Nurhidayatullaili Muhd; Hamid, Sharifah Bee Abd; Boondamnoen, O.; Tai, Mun Foong

2015-01-01

Nitrile butadiene rubber (NBR) gloves are one of the most important personal protective equipments but they are possible to tear off and contaminate food or pharmaceutical and healthcare products during manufacturing and packaging process. High tendency of torn glove remaining in food or products due to white or light flesh-coloured glove is not easy to be detected by naked eyes. In this paper, iron oxide nanoparticles (IONs) selected as additive for NBR to improve its detectability by mean of magnetic properties. IONs synthesized via precipitation method and compounded with NBR latex before casting on petri dish. The properties of IONs were investigated by X-ray Diffractometry (XRD), Transmission Electron Microscope (TEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). Meanwhile NBR/IONs composites were studied by Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). It observed that, synthesized IONs shows of 25.28 nm crystallite with 25.86 nm semipherical (changed as) shape. Meanwhile, Magnetite and maghemite phase are found in range of 670 cm −1 and 700 cm −1 respectively, which it contributes magnetization saturation of 73.96 emu/g at 10,000 G by VSM. Thermal stability and magnetic properties were increased with incorporating IONs into NBR latex up to 20 phr. NBR/IONs 5 phr has the optimum thermal stability, lowest glass transition temperature (−14.83 °C) and acceptable range of magnetization saturation (3.83 emu/g at 10,000 G) to form NBR gloves with magnetic detectability. - Highlights: • We synthesized IONs with high magnetization saturation (M s ). • High M s of IONs were incorporated into NBR latex in order to induce magnetic properties in the NBR composite. • Introduction of IONs into NBR latex would improve thermal properties. • The produced NBR/IONs 5 phr composite exceeded the minimum magnetic moment sensor of the detector. • They have high potential for the

Effect of magnetic and thermal properties of iron oxide nanoparticles (IONs) in nitrile butadiene rubber (NBR) latex

Energy Technology Data Exchange (ETDEWEB)

Ong, Hun Tiar; Julkapli, Nurhidayatullaili Muhd; Hamid, Sharifah Bee Abd, E-mail: sharifahbee@um.edu.my; Boondamnoen, O.; Tai, Mun Foong

2015-12-01

Nitrile butadiene rubber (NBR) gloves are one of the most important personal protective equipments but they are possible to tear off and contaminate food or pharmaceutical and healthcare products during manufacturing and packaging process. High tendency of torn glove remaining in food or products due to white or light flesh-coloured glove is not easy to be detected by naked eyes. In this paper, iron oxide nanoparticles (IONs) selected as additive for NBR to improve its detectability by mean of magnetic properties. IONs synthesized via precipitation method and compounded with NBR latex before casting on petri dish. The properties of IONs were investigated by X-ray Diffractometry (XRD), Transmission Electron Microscope (TEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). Meanwhile NBR/IONs composites were studied by Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). It observed that, synthesized IONs shows of 25.28 nm crystallite with 25.86 nm semipherical (changed as) shape. Meanwhile, Magnetite and maghemite phase are found in range of 670 cm{sup −1} and 700 cm{sup −1} respectively, which it contributes magnetization saturation of 73.96 emu/g at 10,000 G by VSM. Thermal stability and magnetic properties were increased with incorporating IONs into NBR latex up to 20 phr. NBR/IONs 5 phr has the optimum thermal stability, lowest glass transition temperature (−14.83 °C) and acceptable range of magnetization saturation (3.83 emu/g at 10,000 G) to form NBR gloves with magnetic detectability. - Highlights: • We synthesized IONs with high magnetization saturation (M{sub s}). • High M{sub s} of IONs were incorporated into NBR latex in order to induce magnetic properties in the NBR composite. • Introduction of IONs into NBR latex would improve thermal properties. • The produced NBR/IONs 5 phr composite exceeded the minimum magnetic moment sensor of the detector. • They have high

Associação entre aplasia segmentar de veia safena magna e varizes em membros inferiores avaliada pelo ecocolor Doppler

Directory of Open Access Journals (Sweden)

Amélia Cristina Seidel

2015-09-01

Full Text Available ResumoContextoHá diferenças individuais no diâmetro da veia safena magna (VSM em membros normais e doentes; sendo possível a identificação dessas alterações pelo ecocolor Doppler.ObjetivoAvaliar a associação da aplasia segmentar da VSM com a presença de varizes e/ou insuficiência da mesma em membros inferiores, usando o ecocolor Doppler em pacientes com clínica de doença venosa crônica (DVC.Métodos1.408 pacientes com queixas compatíveis de DVC de membros inferiores, sendo 1.286 do sexo feminino, com idade entre 17 e 85 anos, examinados com ecocolor Doppler. Foram incluídos aqueles com classificação CEAP clínica C0 a C4. Pela avaliação clínica, a amostra foi distribuída em grupo A, pacientes com varizes, e grupo B, aqueles sem varizes. O ecocolor Doppler determinou se havia aplasia da VSM pela análise do seu trajeto no compartimento safeno e presença de veias varicosas nos diferentes sítios. Para estatística, foram considerados os testes Qui-quadrado ou Exato de Fisher e uma análise de resíduos em tabelas, com nível de significância de 5%.ResultadosNo grupo A houve 479 (83,9% de VSM insuficientes, 169 (38,2% com aplasia e 71 (80,7% com insuficiência e aplasia associadas. No grupo B, houve 92 (16,1% de VSM insuficientes, 273 (61,8% com aplasia e 17 (19,3% com insuficiência e aplasia associadas.ConclusãoA aplasia segmentar da VSM ocorre mais em membros inferiores que não apresentam varizes e/ou insuficiência da mesma, mas considerando-se a presença da associação de aplasia e insuficiência, houve maior incidência no grupo de membros que apresentavam varizes.

Impaired myogenic tone in mesenteric arteries from overweight rats

Directory of Open Access Journals (Sweden)

Sweazea Karen L

2012-03-01

Full Text Available Abstract Background Rats fed high fat (HFD or high sucrose (HSD diets develop increased adiposity as well as impaired vasodilatory responsiveness stemming from oxidative stress. Moreover, HFD rats become hypertensive compared to either control (Chow or HSD fed rats, suggesting elevated vascular tone. We hypothesized that rats with increased adiposity and oxidative stress demonstrate augmented pressure-induced vasoconstriction (i.e. myogenic tone that could account for the hypertensive state. Methods Male Sprague-Dawley rats were fed Chow, HFD or HSD for 6 weeks. The effects of oxidative stress and endogenous nitric oxide on myogenic responses were examined in small mesenteric arteries by exposing the arteries to incremental intraluminal pressure steps in the presence of antioxidants or an inhibitor of nitric oxide synthase, LNNA (100 μM. Results Contrary to the hypothesis, rats fed either HSD or HFD had significantly impaired myogenic responses despite similar vascular morphology and passive diameter responses to increasing pressures. Vascular smooth muscle (VSM calcium levels were normal in HFD arteries suggesting that diminished calcium sensitivity was responsible for the impaired myogenic response. In contrast, VSM calcium levels were reduced in HSD arteries but were increased with pre-exposure of arteries to the antioxidants tiron (10 mM and catalase (1200 U/mL, also resulting in enhanced myogenic tone. These findings show that oxidative stress impairs myogenic tone in arteries from HSD rats by decreasing VSM calcium. Similarly, VSM calcium responses were increased in arteries from HFD rats following treatment with tiron and catalase, but this did not result in improved myogenic tone. Nitric oxide is involved in the impaired myogenic response in HFD, but not HSD, rats since inhibition with LNNA resulted in maximal myogenic responses at lower intraluminal pressures and VSM calcium levels, further implicating reduced calcium sensitivity in

Structural and magnetic properties of single-crystalline Co-doped barium titanate nanoparticles

International Nuclear Information System (INIS)

Liu Hongxue; Cao Baobao; O'Connor, Charles J.

2010-01-01

Undoped and Co-doped BaTiO 3 nanoparticles were synthesized by a one-step sol-precipitation method. For all the samples, X-ray diffraction showed characteristic diffraction lines for BaTiO 3 without the indication of secondary phases. High-resolution transition electron microscopy images showed that BaTiO 3 nanoparticles exhibit the nature of single-crystal. Magnetometry revealed that all the Co-doped BaTiO 3 samples show paramagnetic behaviors and Co ions in BaTiO 3 are present as isolated paramagnetic centers. This is contrasted to several reported cases of ferromagnetism in Co-doped BaTiO 3 .

Magnetic properties of screen-printed (Y0.5Sm0.5)Co5 magnet arrays

International Nuclear Information System (INIS)

Bueno-Baques, D.; Maldonado-Chavez, L.; Hidalgo-Gonzalez, J.L.; Matutes-Aquino, J.A.; Corral-Flores, V.

2007-01-01

(Y 0.5 Sm 0.5 )Co 5 magnet arrays of square μdots of 300 μm were prepared by screen printing. A well controlled paste like ink prepared with the (Y 0.5 Sm 0.5 )Co 5 nanoparticles and a mixture of organic solvent and polymer was used to print different pattern arrays. (Y 0.5 Sm 0.5 )Co 5 nanoparticles were obtained by mechanical milling starting from arc melted ingots and heat treated in Ar atmosphere. Two different heat treatment were considered, resulting in powders with different magnetic properties. The microstructure of the magnet arrays was studied by scanning electron microscopy (SEM). An isotropic homogeneous distribution of the nanoparticles inside the μdots was observed. The final shape of the μdots in the array was found to be highly dependent on the squeeze pressure and speed over the mesh. Magnetic properties were studied by pulsed field magnetometry and vibrating sample magnetometry at room temperature. The micro size arrays showed lower saturation magnetization and a slightly increase in the coercive field. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Vacancy ordered γ-Fe{sub 2}O{sub 3} nanoparticles functionalized with nanohydroxyapatite: XRD, FTIR, TEM, XPS and Mössbauer studies

Energy Technology Data Exchange (ETDEWEB)

Ramos Guivar, Juan A., E-mail: juan.ramos5@unmsm.edu.pe [Faculty of Physical Sciences, National University of San Marcos, P. O. Box 14- 0149, Lima 14 (Peru); Sanches, Edgar A., E-mail: sanches.ufam@gmail.com [Federal University of Amazonas, Department of Physics, Manaus/AM (Brazil); Bruns, Florian, E-mail: f.bruns@tu-braunschweig.de [Institut für Physik der Kondensierten Materie, Technische Universität Braunschweig, 38110 Braunschweig (Germany); Sadrollahi, Elaheh, E-mail: elahe.sadrollahi@gmail.com [Institut für Physik der Kondensierten Materie, Technische Universität Braunschweig, 38110 Braunschweig (Germany); Morales, M.A., E-mail: marco.moralestorres@gmail.com [Department of Theoretical and Experimental Physics, UFRN, Natal, RN 59078- 970 (Brazil); López, Elvis O., E-mail: lopmezel@gmail.com [Brazilian Center for Research in Physics (CBPF), Rio de Janeiro, RJ 22290-180 (Brazil); Litterst, F. Jochen, E-mail: litterst@cbpf.br [Institut für Physik der Kondensierten Materie, Technische Universität Braunschweig, 38110 Braunschweig (Germany); Brazilian Center for Research in Physics (CBPF), Rio de Janeiro, RJ 22290-180 (Brazil)

2016-12-15

Graphical abstract: Possible bonding configuration in the γ-Fe{sub 2}O{sub 3} nanoparticles functionalized with nanoHAp. - Highlights: • Coprecipitation in alkaline medium for the synthesis of vacancy ordered γ-Fe{sub 2}O{sub 3}@HAp nanocomposite. • Samples were characterized by XRD, FTIR, XPS, TEM, VSM and Mössbauer spectroscopy. • The functionalization is explained with the binding of two oxygens of chemisorbed H{sub 2}O molecules at the common interface of HAp/C{sub 6}H{sub 8}O{sub 7}/γ-Fe{sub 2}O{sub 3}. - Abstract: Vacancy ordered maghemite (γ-Fe{sub 2}O{sub 3}) nanoparticles functionalized with nanohydroxyapatite (HAp – Ca{sub 10}(PO{sub 4}) {sub 6}(OH){sub 2}) have been successfully synthesized using an inexpensive co-precipitation chemical route. Evidence for the presence of vacancy order in maghemite was shown by the superstructure lines observed in X-ray diffraction. The adsorption of carboxyl groups of citric acid (C{sub 6}H{sub 8}O{sub 7}) onto γ-Fe{sub 2}O{sub 3} nanoparticles was investigated by FTIR, XPS and Mössbauer spectroscopy. From XPS surface analysis, two binding energies related to oxygen were attributed to bindings between C{sub 6}H{sub 8}O{sub 7}/γ- Fe{sub 2}O{sub 3} and C{sub 6}H{sub 8}O{sub 7}/HAp from an interfacial reaction promoted by strongly adsorbed H{sub 2}O molecules at the surface of these nanomaterials. Le Bail refinement of the XRD patterns showed the formation of well-crystallized pure tetragonal maghemite before and after functionalization with nanoHAp. The temperature dependence of hyperfine parameters of pure and functionalized γ-Fe{sub 2}O{sub 3} nanoparticles was investigated via Mössbauer spectroscopy. TEM revealed the formation of quasi-spherical γ- Fe{sub 2}O{sub 3} nanoparticles with an average diameter of ca. 12 nm and 16 nm before and after functionalization with nanoHAp in agreement with Le Bail refinement. Magnetometry measurements showed a saturation magnetization of 12 emu/g and a blocking

Spin and Charge Transport in 2D Materials and Magnetic Insulator/Metal Heterostructures

Science.gov (United States)

Amamou, Walid

Spintronic devices are very promising for future information storage, logic operations and computation and have the potential to replace current CMOS technology approaching the scaling limit. In particular, the generation and manipulation of spin current enables the integration of storage and logic within the same circuit for more powerful computing architectures. In this thesis, we examine the manipulation of spins in 2D materials such as graphene and metal/magnetic insulator heterostructures. In particular, we investigate the feasibility for achieving magnetization switching of a nanomagnet using graphene as a nonmagnetic channel material for All Spin Logic Device applications. Using in-situ MBE deposition of nanomagnet on graphene spin valve, we demonstrate the presence of an interfacial spin dephasing at the interface between the graphene and the nanomagnet. By introducing a Cu spacer between the nanomagnet and graphene, we demonstrate that this interfacial effect is related to an exchange interaction between the spin current and the disordered magnetic moment of the nanomagnet in the first monolayer. In addition to the newly discovered interfacial spin relaxation effect, the extracted contact resistance area product of the nanomagnet/graphene interface is relatively high on the order of 1Omicrom2. In practice, reducing the contact resistance will be as important as eliminating the interfacial relaxation in order to achieve magnetization switching. Furthermore, we examine spin manipulation in a nonmagnetic Pt using an internal magnetic exchange field produced by the adjacent magnetic insulator CoFe2O4 grown by MBE. Here, we report the observation of a strong magnetic proximity effect of Pt deposited on top of a perpendicular magnetic anisotropy (PMA) inverse spinel material Cobalt Ferrite (CFO, CoFe 2O4). The CFO was grown by MBE and its magnetization was characterized by Vibrating Sample Magnetometry (VSM) demonstrating the strong out of plane magnetic

Finite size effects on the experimental observables of the Glauber model: a theoretical and experimental investigation

International Nuclear Information System (INIS)

Vindigni, A.; Bogani, L.; Gatteschi, D.; Sessoli, R.; Rettori, A.; Novak, M.A.

2004-01-01

We investigate the relaxation time, τ, of a dilute Glauber kinetic Ising chain obtained by ac susceptibility and SQUID magnetometry on a Co(II)-organic radical Ising 1D ferrimagnet doped with Zn(II). Theoretically we predicted a crossover in the temperature-dependence of τ, when the average segment is of the same order of the correlation length. Comparing the experimental results with theory we conclude that in the investigated temperature range the correlation length exceeds the finite length also in the pure sample

Finite size effects on the experimental observables of the Glauber model: a theoretical and experimental investigation

Energy Technology Data Exchange (ETDEWEB)

Vindigni, A. E-mail: alessandro.vindigni@unifi.it; Bogani, L.; Gatteschi, D.; Sessoli, R.; Rettori, A.; Novak, M.A

2004-05-01

We investigate the relaxation time, {tau}, of a dilute Glauber kinetic Ising chain obtained by ac susceptibility and SQUID magnetometry on a Co(II)-organic radical Ising 1D ferrimagnet doped with Zn(II). Theoretically we predicted a crossover in the temperature-dependence of {tau}, when the average segment is of the same order of the correlation length. Comparing the experimental results with theory we conclude that in the investigated temperature range the correlation length exceeds the finite length also in the pure sample.

Finite size effects on the experimental observables of the Glauber model: a theoretical and experimental investigation

Science.gov (United States)

Vindigni, A.; Bogani, L.; Gatteschi, D.; Sessoli, R.; Rettori, A.; Novak, M. A.

2004-05-01

We investigate the relaxation time, τ, of a dilute Glauber kinetic Ising chain obtained by ac susceptibility and SQUID magnetometry on a Co(II)-organic radical Ising 1D ferrimagnet doped with Zn(II). Theoretically we predicted a crossover in the temperature-dependence of τ, when the average segment is of the same order of the correlation length. Comparing the experimental results with theory we conclude that in the investigted temperature range the correlation length exceeds the finite length also in the pure sample.

EVALUATION OF VALUE STREAM MAPPING IN MANUFACTURING SYSTEMS REDESIGNING

OpenAIRE

Serrano , Ibon; Ochoa Laburu , Carlos; De Castro , Rodolfo

2008-01-01

Abstract The Value Stream Mapping (VSM) technique, developed within the lean production paradigm, was presented as an innovative graphic technique to help practitioners redesign production systems. This paper presents the results of a project whose main purpose is to evaluate the real applicability of VSM to redesign disconnected flow lines based on manufacturing environments with a diversity of logistical problems. The research was developed using multiple case study methodology i...

Paramagnetic behavior at room temperature of Zn{sub 1−x}Mn{sub x}Te nanocrystals grown in a phosphate glass matrix by the fusion method

Energy Technology Data Exchange (ETDEWEB)

Silva, Alessandra S., E-mail: alessandra@mestrado.ufu.br [Universidade Federal de Uberlândia, Instituto de Física, Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Uberlândia CEP: 38400-902 (Brazil); Franco, Adolfo; Pelegrini, Fernando [Instituto de Física, Universidade Federal de Goiás, C. P. 131, 74001-970 Goiânia, GO (Brazil); Dantas, Noelio O. [Universidade Federal de Uberlândia, Instituto de Física, Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Uberlândia CEP: 38400-902 (Brazil)

2015-10-25

This work reports on the synthesis and characterization of Zn{sub 1−x}Mn{sub x}Te nanocrystals (NCs) with Mn doping concentration x varying from 0.000 to 0.800. Physical properties of samples were studied by transmission electron microscopy, magnetic force microscopy, vibrating sample magnetometry and electron paramagnetic resonance spectroscopy. Room temperature experiments revealed the size of NCs, the growth of magnetization and non-linear dependence of magnetic susceptibility on the concentration of Mn{sup 2+} ions; samples with low concentrations revealed the presence of ions in the interior and near the surface of the NCs. The results obtained confirm the paramagnetic behavior of Zn{sub 1−x}Mn{sub x}Te NCs at room temperature.

Anaerobic digestion of autoclaved and untreated food waste

International Nuclear Information System (INIS)

Tampio, Elina; Ervasti, Satu; Paavola, Teija; Heaven, Sonia; Banks, Charles; Rintala, Jukka

2014-01-01

Highlights: • Autoclaving decreased the formation of NH4-N and H 2 S during food waste digestion. • Stable digestion was achieved with untreated and autoclaved FW at OLR 6 kg VS/m 3 day. • Use of acclimated inoculum allowed very rapid increases in OLR. • Highest CH 4 yields were observed at OLR 3 kg VS/m 3 day with untreated FW. • Autoclaved FW produced highest CH 4 yields during OLR 4 kgVS/m 3 day. - Abstract: Anaerobic digestion of autoclaved (160 °C, 6.2 bar) and untreated source segregated food waste (FW) was compared over 473 days in semi-continuously fed mesophilic reactors with trace elements supplementation, at organic loading rates (OLRs) of 2, 3, 4 and 6 kg volatile solids (VS)/m 3 d. Methane yields at all OLR were 5–10% higher for untreated FW (maximum 0.483 ± 0.013 m 3 CH 4 /kg VS at 3 kg VS/m 3 d) than autoclaved FW (maximum 0.439 ± 0.020 m 3 CH 4 /kg VS at 4 kg VS/m 3 d). The residual methane potential of both digestates at all OLRs was less than 0.110 m 3 CH 4 /kg VS, indicating efficient methanation in all cases. Use of acclimated inoculum allowed very rapid increases in OLR. Reactors fed on autoclaved FW showed lower ammonium and hydrogen sulphide concentrations, probably due to reduced protein hydrolysis as a result of formation of Maillard compounds. In the current study this reduced biodegradability appears to outweigh any benefit due to thermal hydrolysis of ligno-cellulosic components

Synthesis and application of novel ion-imprinted polymer coated magnetic multi-walled carbon nanotubes for selective solid phase extraction of lead(II) ions

Energy Technology Data Exchange (ETDEWEB)

Fayazi, Maryam, E-mail: maryam.fayazi@yahoo.com [Mineral Industries Research Center, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Young Researchers Society, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Taher, Mohammad Ali [Department of Chemistry, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Afzali, Daryoush [Department of Environment, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of); Mostafavi, Ali [Department of Chemistry, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Ghanei-Motlagh, Masoud, E-mail: m.ghaneimotlagh@yahoo.com [Young Researchers Society, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Department of Chemistry, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

2016-03-01

In this study, novel magnetic ion-imprinted polymer (MIIP) nanoparticles were utilized for the sensitive and selective detection of Pb(II) ions by graphite furnace atomic absorption spectrometry (GFAAS). The Pb(II)-imprinted polymer was synthesized by using 4-vinylpyridine (4VP) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, 2,3,5,6-tetra(2-pyridyl) pyrazine (TPPZ) as the chelating agent and magnetic multi-walled carbon nanotubes (MMWCNTs) as the carrier. The synthesized MIIP materials were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). Various analytical parameters such as extraction and desorption time, eluent type and concentration, pH and sample volume were systematically examined. The selectivity of MIIP sorbent for Pb(II) ions in the presence of some cations was also evaluated. The limit of detection (LOD, 3S{sub b}) and the relative standard deviation (RSD, n = 8, c = 25 ng L{sup −1}) were found to be 2.4 ng L{sup −1} and 5.6%, respectively. The maximum sorption capacity of the MIIP for Pb(II) was found to be 48.1 mg g{sup −1}. Finally, the proposed analytical procedure was successfully applied to monitoring lead in human hair and water samples with satisfactory results for the spiked samples. - Highlights: • A selective and sensitive method based on MSPE-GFAAS was proposed. • The MIIP nanoparticles were characterized using FE-SEM, XRD, VSM and FT-IR techniques. • The synthesized MIIP material is efficient at extracting lead ions. • The method was applied to determine lead ions in several real samples.

Impact of ignition temperature on particle size and magnetic properties of CoFe{sub 2}O{sub 4} nanoparticles prepared by self-propagated MILD combustion technique

Energy Technology Data Exchange (ETDEWEB)

Kaliyamoorthy, Venkatesan; Rajan Babu, D., E-mail: drajanbabu@vit.ac.in; Saminathan, Madeswaran

2016-11-15

We prepared nanocrystalline CoFe{sub 2}O{sub 4} by changing its ignition temperatures, using moderate and intense low-oxygen dilution (MILD) combustion technique. The effect of ignition temperature on the particle size and its magnetic behavior was investigated by HR-TEM and VSM respectively. We observed a vast change in the structural behavior and the magnetic properties of the prepared samples. X-ray diffraction studies revealed that the resultant samples had single phase with different grain sizes from 23±5 nm to 16±5 nm, which was understood by observing the growth of the grains through heat released from the combustion reaction. FE-SEM analysis showed high porosity with heterogeneous distribution of the pore size based on the adiabatic temperature and EPMA analysis, which confirmed the elemental compositions of the prepared samples. The saturation magnetization values measured at room temperature, employing vibrating sample magnetometer (VSM) decreased gradually from 50 to 34 emu/g when the ignition temperature was increased from 243 °C to 400 °C. Some of Fe ions on the B sites moved periodically to the A sites because of quenching treatment. The presence of Fe{sup 2+} ions in the existing ferrite structure ruled the magnetic behavior of the sample, as confirmed by the Mössbauer analysis. - Highlights: • CoFe{sub 2}O{sub 4} magnetic nanoparticles were prepared by MILD combustion technique. • Structural behavior and magnetic properties were changed by ignition temperature. • Formation of ferrite complex was confirmed by using FT-IR spectroscopy. • FE-SEM image confirmed the combustion nature by exhibiting the pores and voids. • The cationic distributions were investigated by the Mössbauer analysis.

Experimental insight into the magnetic and electrical properties of amorphous Ge1-xMnx

Science.gov (United States)

Conta, Gianluca; Amato, Giampiero; Coïsson, Marco; Tiberto, Paola

2017-12-01

We present a study of the electrical and magnetic properties of the amorphous Ge1-xMnx.DMS, with 2% ≤ x ≤ 17%, by means of SQUID magnetometry and low temperature DC measurements. The thin films were grown by physical vapour deposition at 50°C in ultrahigh vacuum. The DC electrical characterizations show that variable range hopping is the main mechanism of charge transport below room temperature. Magnetic characterization reveals that a unique and smooth magnetic transition is present in our samples, which can be attributed to ferromagnetic percolation of bound magnetic polarons.

Scaling analysis of [Fe(pyrazole)4]2[Nb(CN)8] molecular magnet

Science.gov (United States)

Konieczny, P.; Pełka, R.; Zieliński, P. M.; Pratt, F. L.; Pinkowicz, D.; Sieklucka, B.; Wasiutyński, T.

2013-10-01

The critical behaviour of the three dimensional (3D) molecular magnet {[FeII(pirazol)4]2[NbIV(CN)8]·4H2O}n has been studied with the use of experimental techniques such as ac magnetometry and zero field μSR spectroscopy. The sample orders magnetically below Tc=7.8 K. The measurements allowed to determine static exponents β, γ, and the dynamic exponent w. The resulting exponent values indicate that the studied system belongs to the universality class of the 3D Heisenberg model.

Detection of discretized single-shell penetration in mesoscopic vortex matter

International Nuclear Information System (INIS)

Dolz, M I; Fasano, Y; Bolecek, N R Cejas; Pastoriza, H; Konczykowski, M; Beek, C J van der

2014-01-01

We investigated configurational changes in mesoscopic vortex matter with less than thousand vortices during flux penetration in freestanding 50 μm diameter disks of Bi 2 Sr 2 CaCu 2 O 8+δ . High-resolution AC and DC local magnetometry data reveal oscillations in the transmittivity echoed in peaks in the third-harmonics magnetic signal fainting on increasing vortex density. By means of extra experimental evidence and a simple geometrical analysis we show that these features fingerprint the discretized entrance of single-shells of vortices having a shape that mimics the sample edge

Fabrication of graphene/Fe{sub 3}O{sub 4}@polythiophene nanocomposite and its application in the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from environmental water samples

Energy Technology Data Exchange (ETDEWEB)

Mehdinia, Ali, E-mail: mehdinia@inio.ac.ir [Department of Marine Science, Iranian National Institute for Oceanography and Atmospheric Science, Tehran (Iran, Islamic Republic of); Khodaee, Nader; Jabbari, Ali [Department of Chemistry, Faculty of Science, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of)

2015-04-08

Highlights: • G/Fe{sub 3}O{sub 4}@polythiophene as a novel sorbent for MSPE of PAHs. • Polythiopheneas an efficient modifier of G/Fe{sub 3}O{sub 4}. • G sheets can act as a “support” for the growth of Fe{sub 3}O{sub 4} nanoparticles. • G sheets can act as a “spacer” for the inhibition of NPs aggregation. - Abstract: Polythiophene (PT) was used as a surface modifier of graphene/Fe{sub 3}O{sub 4} (G/Fe{sub 3}O{sub 4}) composite to increase merit of it, and also overcome some limitations and disadvantages of using G/Fe{sub 3}O{sub 4} alone as solid phase extraction (SPE) sorbent. An in-situ chemical polymerization method was employed to prepare G/Fe{sub 3}O{sub 4}@PT nanocomposites. Application of this newly designed material in the magnetic SPE (MSPE) of polycyclic aromatic hydrocarbons (PAHs), as model analytes, in the environmental water samples was investigated. The characterization of the hybrid material was performed using transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray analysis, Fourier transform-infrared (FT-IR) spectroscopy and vibrating sample magnetometry. Seven important parameters, affecting the extraction efficiency of PAHs, including: amount of adsorbent, adsorption and desorption times, type and volume of the eluent solvent, initial sample volume and salt content of the sample were evaluated. The optimum extraction conditions were obtained as: 4 min for extraction time, 20 mg for sorbent amount, 100 mL for initial sample volume, toluene as desorption solvent, 0.6 mL for desorption solvent volume, 6 min for desorption time and 30% (w/v) for NaCl concentration. Good performance data were obtained at the optimized conditions. Detection limits were in the range of 0.009–0.020 μg L{sup −1} in the real matrix. The calibration curves were linear over the concentration ranges from 0.03 to 80 μg L{sup −1} with correlation coefficients (R{sup 2}) between 0.995 and 0.998 for all the analytes

Gd3+ doped Mn-Zn soft ferrite nanoparticles: Superparamagnetism and its correlation with other physical properties

International Nuclear Information System (INIS)

Thakur, Prashant; Sharma, Rohit; Sharma, Vineet; Barman, P.B.; Kumar, Manoj; Barman, Dipto; Katyal, S.C.; Sharma, Pankaj

2017-01-01

Highlights: • Superparamagnetic nanoparticles of Gd doped Mn-Zn spinel ferrites synthesized by co-precipitation. • XRD and FTIR studies justify the formation of cubical spinel structure. • Maximum saturation magnetization and magnetic moment at x = 0.025. • PL spectra shows blue shift for x = 0.025, 0.075 and may be attributed to quantum confinement. - Abstract: Superparamagnetic nanoparticles are very important in biomedicine due to their various applications like drug delivery, gene delivery in the body and also used for hyperthermia. In the present work, superparamagnetic nanoparticles of Mn 0.5 Zn 0.5 Gd x Fe 2-x O 4 (x = 0, 0.025, 0.050, 0.075, 0.1) ferrites have been prepared by co-precipitation method. Thorough characterizations (XRD, FTIR, FE-SEM, EDS, VSM and fluorescence spectroscopy) have proved the formation of cubical spinel superparamagnetic nanoparticles of soft ferrites. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. With the addition of Gd 3+ nanoparticles have shown the superparamagnetism at room temperature confirmed by VSM analysis. Photoluminescence (PL) spectra shows a blue shift (for x = 0.025, 0.075) which may be due to quantum confinement.

Validation of a virtual source model of medical linac for Monte Carlo dose calculation using multi-threaded Geant4

Science.gov (United States)

Aboulbanine, Zakaria; El Khayati, Naïma

2018-04-01

The use of phase space in medical linear accelerator Monte Carlo (MC) simulations significantly improves the execution time and leads to results comparable to those obtained from full calculations. The classical representation of phase space stores directly the information of millions of particles, producing bulky files. This paper presents a virtual source model (VSM) based on a reconstruction algorithm, taking as input a compressed file of roughly 800 kb derived from phase space data freely available in the International Atomic Energy Agency (IAEA) database. This VSM includes two main components; primary and scattered particle sources, with a specific reconstruction method developed for each. Energy spectra and other relevant variables were extracted from IAEA phase space and stored in the input description data file for both sources. The VSM was validated for three photon beams: Elekta Precise 6 MV/10 MV and a Varian TrueBeam 6 MV. Extensive calculations in water and comparisons between dose distributions of the VSM and IAEA phase space were performed to estimate the VSM precision. The Geant4 MC toolkit in multi-threaded mode (Geant4-[mt]) was used for fast dose calculations and optimized memory use. Four field configurations were chosen for dose calculation validation to test field size and symmetry effects, , , and for squared fields, and for an asymmetric rectangular field. Good agreement in terms of formalism, for 3%/3 mm and 2%/3 mm criteria, for each evaluated radiation field and photon beam was obtained within a computation time of 60 h on a single WorkStation for a 3 mm voxel matrix. Analyzing the VSM’s precision in high dose gradient regions, using the distance to agreement concept (DTA), showed also satisfactory results. In all investigated cases, the mean DTA was less than 1 mm in build-up and penumbra regions. In regards to calculation efficiency, the event processing speed is six times faster using Geant4-[mt] compared to sequential

Impact of accidents on organizational aspects of nuclear utilities

OpenAIRE

Spurgin, A. J.; Stupples, D.

2012-01-01

This paper applies the Beer Viable Systems Model (VSM) approach to the study of nuclear accidents. It relates how organizational structures and rules are affected by accidents in the attempt to improve safety and reduce risk. The paper illustrates this process with reference to a number of accidents. The dynamic cybernetic aspect of the VSM approach to organizations yields a better understanding of the need for good decision-making to minimize risk and how organizations really operate.

Systems thinking benefits in supply change management:an illustration of the viable systems model in a supply chain

OpenAIRE

Chronéer, Diana; Mirijamdotter, Anita

2009-01-01

Existing product development models are solely an organisational matter. They do not take into consideration the whole supply chain and its different actors. We investigate in this paper how Supply Chain Management (SCM) and Viable System Model (VSM) can support and create an effective use of information in product development and hence identify critical linkages in the supply chain. The aim is to introduce VSM as a framework that enable an analysis of company's supply chains and visualize vi...

Rapid and effective sample cleanup based on graphene oxide-encapsulated core–shell magnetic microspheres for determination of fifteen trace environmental phenols in seafood by liquid chromatography–tandem mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Pan, Sheng-Dong; Chen, Xiao-Hong [Key Laboratory of Health Risk Appraisal for Trace Toxic Chemicals of Zhejiang Province, Ningbo Municipal Center for Disease Control and Prevention, Ningbo, Zhejiang 315010 (China); Ningbo Key Laboratory of Poison Research and Control, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010 (China); Shen, Hao-Yu [Ningbo Institute of Technology, Zhejiang University, Ningbo, Zhejiang 315100 (China); Li, Xiao-Ping [Key Laboratory of Health Risk Appraisal for Trace Toxic Chemicals of Zhejiang Province, Ningbo Municipal Center for Disease Control and Prevention, Ningbo, Zhejiang 315010 (China); Ningbo Key Laboratory of Poison Research and Control, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010 (China); Cai, Mei-Qiang [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); Zhao, Yong-Gang [Key Laboratory of Health Risk Appraisal for Trace Toxic Chemicals of Zhejiang Province, Ningbo Municipal Center for Disease Control and Prevention, Ningbo, Zhejiang 315010 (China); Ningbo Key Laboratory of Poison Research and Control, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010 (China); Jin, Mi-Cong, E-mail: jmcjc@163.com [Key Laboratory of Health Risk Appraisal for Trace Toxic Chemicals of Zhejiang Province, Ningbo Municipal Center for Disease Control and Prevention, Ningbo, Zhejiang 315010 (China); Ningbo Key Laboratory of Poison Research and Control, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010 (China)

2016-05-05

In this study, graphene oxide-encapsulated core–shell magnetic microspheres (GOE-CS-MM) were fabricated by a self-assemble approach between positive charged poly(diallyldimethylammonium) chloride (PDDA)-modified Fe{sub 3}O{sub 4}@SiO{sub 2} and negative charged GO sheets via electrostatic interaction. The as-prepared GOE-CS-MM was carefully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer analysis (VSM), and X-ray photoelectron spectroscopy (XPS), and was used as a cleanup adsorbent in magnetic solid-phase extraction (MSPE) for determination of 15 trace-level environmental phenols in seafood coupled to liquid chromatography–tandem mass spectrometry (LC–MS/MS). The obtained results showed that the GOE-CS-MM exhibited excellent cleanup efficiency and could availably reduce the matrix effect. The cleanup mechanisms were investigated and referred to π–π stacking interaction and hydrogen bond between GOE-CS-MM and impurities in the extracts. Moreover, the extraction and cleanup conditions of GOE-CS-MM toward phenols were optimized in detail. Under the optimized conditions, the limits of detection (LODs) were found to be 0.003–0.06 μg kg{sup −1}, and satisfactory recovery values of 84.8–103.1% were obtained for the tested seafood samples. It was confirmed that the developed method is simple, fast, sensitive, and accurate for the determination of 15 trace environmental phenols in seafood samples. - Highlights: • Novel graphene oxide-encapsulated core-shell magnetic microspheres (GOE-CS-MM) were fabricated by a self-assemble approach. • The as-prepared material GOE-CS-MM exhibited excellent cleanup efficiency and could availably reduce the matrix effect. • The cleanup mechanisms refer to π–π stacking interaction and hydrogen bond. • The developed MSPE–LC–MS/MS method was simple, fast, sensitive and accurate.

Dynamic characteristics of otolith ocular response during counter rotation about dual yaw axes in mice.

Science.gov (United States)

Shimizu, N; Wood, S; Kushiro, K; Yanai, S; Perachio, A; Makishima, T

2015-01-29

The central vestibular system plays an important role in higher neural functions such as self-motion perception and spatial orientation. Its ability to store head angular velocity is called velocity storage mechanism (VSM), which has been thoroughly investigated across a wide range of species. However, little is known about the mouse VSM, because the mouse lacks typical ocular responses such as optokinetic after nystagmus or a dominant time constant of vestibulo-ocular reflex for which the VSM is critical. Experiments were conducted to examine the otolith-driven eye movements related to the VSM and verify its characteristics in mice. We used a novel approach to generate a similar rotating vector as a traditional off-vertical axis rotation (OVAR) but with a larger resultant gravito-inertial force (>1g) by using counter rotation centrifugation. Similar to results previously described in other animals during OVAR, two components of eye movements were induced, i.e. a sinusoidal modulatory eye movement (modulation component) on which a unidirectional nystagmus (bias component) was superimposed. Each response is considered to derive from different mechanisms; modulations arise predominantly through linear vestibulo-ocular reflex, whereas for the bias, the VSM is responsible. Data indicate that the mouse also has a well-developed vestibular system through otoliths inputs, showing its highly conserved nature across mammalian species. On the other hand, to reach a plateau state of bias, a higher frequency rotation or a larger gravito-inertial force was considered to be necessary than other larger animals. Compared with modulation, the bias had a more variable profile, suggesting an inherent complexity of higher-order neural processes in the brain. Our data provide the basis for further study of the central vestibular system in mice, however, the underlying individual variability should be taken into consideration. Copyright © 2014 IBRO. Published by Elsevier Ltd. All

Visual spatial memory is enhanced in female rats (but inhibited in males by dietary soy phytoestrogens

Directory of Open Access Journals (Sweden)

Setchell Kenneth DR

2001-12-01

Full Text Available Abstract Background In learning and memory tasks, requiring visual spatial memory (VSM, males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen. This study examined the influence of phytoestrogens (estrogen-like plant compounds on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB, and cyclooxygenase-2 (COX-2 levels were determined. Results Female rats receiving lifelong exposure to a high-phytoestrogen containing diet (Phyto-600 acquired the maze faster than females fed a phytoestrogen-free diet (Phyto-free; in males the opposite diet effect was identified. In a separate experiment, at 80 days-of-age, animals fed the Phyto-600 diet lifelong either remained on the Phyto-600 or were changed to the Phyto-free diet until 120 days-of-age. Following the diet change Phyto-600 females outperformed females switched to the Phyto-free diet, while in males the opposite diet effect was identified. Furthermore, males fed the Phyto-600 diet had significantly higher phytoestrogen concentrations in a number of brain regions (frontal cortex, amygdala & cerebellum; in frontal cortex, expression of CALB (a neuroprotective calcium-binding protein decreased while COX-2 (an inducible inflammatory factor prevalent in Alzheimer's disease increased. Conclusions Results suggest that dietary phytoestrogens significantly sex-reversed the normal sexually dimorphic expression of VSM. Specifically, in tasks requiring the use of reference, but not working, memory, VSM was enhanced in females fed the Phyto-600 diet, whereas, in males VSM was inhibited by the same diet. These findings suggest that dietary soy derived phytoestrogens can influence learning and memory and alter the expression of proteins involved in neural protection and inflammation in rats.

Effects of Gd substitution on the structural and magnetic properties of strontium hexaferrites

Science.gov (United States)

Litsardakis, G.; Manolakis, I.; Serletis, C.; Efthimiadis, K. G.

2007-09-01

The effect of Gd substitution in M-type strontium hexaferrites has been examined in two series of samples, (Sr1-xGdx)O·5.25Fe2O3 and Sr1-xGdxFe12-xCoxO19, both prepared by the ceramic method, where x=0-0.40. The samples have been characterized by XRD, VSM and SEM-EDAX techniques. All substituted samples present primarily the hexaferrite structure. Sample (Sr0.95Gd)O·5.25Fe2O3 is single phase. Formation of impurity phases is affected by stoichiometry and presence of Co. In Sr-Gd samples, coercivity showed a maximum value of 305 kA/m (3.8 kOe) for x=0.20, while remanence and saturation magnetization did not decrease. Coercivity and magnetization in the Sr-Gd-Co series decreased steadily with substitution degree.

Thermophilic co-digestion feasibility of distillers grains and swine manure: effect of C/N ratio and organic loading rate during high solid anaerobic digestion (HSAD).

Science.gov (United States)

Sensai, P; Thangamani, A; Visvanathan, C

2014-01-01

Anaerobic co-digestion of high solids containing distillers grains and swine manure (total solids, 27 +/- 2% and 18 +/- 2%, respectively) was evaluated in this study to assess the effect of C/N ratio and organic loading rate (OLR). Feed mixture was balanced to achieve a C/N ratio of 30/1 by mixing distillers grains and swine manure. Pilot-scale co-digestion of distillers grains and swine manure was carried out under thermophilic conditions in the continuous mode for seven different OLRs from R1 to R7 (3.5, 5, 6, 8, 10, 12 and 14 kg VS/m3 day) under high solid anaerobic digestion. The methane yield and volatile solid (VS) removal were consistent; ranging from 0.33 to 0.34 m3CH4/kg VS day and 50-53%, respectively, until OLR 8 kg VS/m3 day. After which methane yield and VS removal significantly decreased to 0.26 m3 CH4/kg VS day and 42%, respectively, when OLR was increased to 14 kg VS/m3 day. However, during operation, at OLR of 10 kg VS/m3 day, the methane yield and VS removal increased after the 19th day to 0.33 m3 CH4/kg VS day and 46%, respectively, indicating that a longer acclimatization period is required by methanogens at a higher loading rate.

Facile synthesis of multifunctional attapulgite/Fe3O4/polyaniline nanocomposites for magnetic dispersive solid phase extraction of benzoylurea insecticides in environmental water samples

International Nuclear Information System (INIS)

Yang, Xiaoling; Qiao, Kexin; Ye, Yiren; Yang, Miyi; Li, Jing; Gao, Haixiang; Zhang, Sanbing; Zhou, Wenfeng; Lu, Runhua

2016-01-01

In this study, the superparamagnetic attapulgite/Fe 3 O 4 /polyaniline (ATP/Fe 3 O 4 /PANI) nanocomposites were successfully synthesized by a one-pot method. Fe (III) was applied as both the oxidant for the oxidative polymerization of aniline and the single iron source of Fe 3 O 4 formed by the redox reaction between aniline and Fe (III). The ATP/Fe 3 O 4 /PANI was used as sorbent for magnetic dispersive solid phase extraction (MDSPE) of benzoylurea insecticides (BUs) in environmental water samples. The as-prepared nanocomposite sorbents were characterized by Fourier transform infrared spectra (FT-IR), X Ray diffraction (XRD), scanning electron microscopy(SEM), transmission electron microscopy (TEM), and vibrating sample magnetometry. Various experimental parameters affecting the ATP/Fe 3 O 4 /PANI-based MDSPE procedure, including the composition of the nanocomposite sorbents, amount of ATP/Fe 3 O 4 /PANI nanocomposites, vortex time, pH, and desorption conditions were investigated. Under the optimal conditions, a good linearity was observed for all target analytes, with correlation coefficients (r 2 ) ranging from 0.9985 to 0.9997; the limits of detection (LOD) were in the range of 0.02–0.43 μg L −1 , and the recoveries of analytes using the proposed method ranged between 77.37% and 103.69%. The sorbents exhibited an excellent reproducibility in the range of 1.52–5.27% in extracting the five target analytes. In addition, the intra-day and inter-day precision values were found to be in the range of 0.78–6.86% and 1.66–8.41%, respectively. Finally, the proposed ATP/Fe 3 O 4 /PANI-based MDSPE method was successfully applied to analyze river water samples by rapid preconcentration of BUs. - Highlights: • A novel superparamagnetic ATP/Fe 3 O 4 /PANI nanocomposite was first introduced in MDSPE. • ATP/Fe 3 O 4 /PANI nanocomposites exhibited fast adsorption and desorption kinetics. • An excellent sorbent-to-sorbent reproducibility was demonstrated in the

Use of reduced doses of eCG applied by different routes in the TAI program in Santa Ines sheep

Directory of Open Access Journals (Sweden)

Karla Dias Antunes-Melo

2015-06-01

Full Text Available The aims of this study were to improve the cost-benefit ratio of the application of artificial insemination in fixed time (TAI by the transcervical route in sheep, to test the dosage reduction and the use of the vulvar submucosa (VSM route as an alternative for the application of equine chorionic gonadotropin (eCG on the efficiency of the synchronization protocol and fertility to artificial insemination (AI and to measure the level of cortisol in ewes as a result the application of this biotechnique. Blood samples were collected before AI, immediately after AI and seven days after AI. Six groups of twenty animals were used, and each group received doses of 200, 300 and 400 IU of eCG by the intramuscular route (IM and VSM. Estrus was detected, and 48 hours later, the inseminations were performed by the transcervical route. Among the 120 treated ewes, 87.5% came in estrus. The percentage of the intrauterine deposition of semen was 88.3%. The pregnancy rate ranged from 20 to 70% between treatments, with an average of 46.66%. The VSM route was viable for the application of eCG in doses of 300 and 400 IU. The reduction in the eCG dose to 200 IU by the IM route reduces costs while maintaining the efficiency of estrus synchronization protocols and TAI with frozen semen in Santa Ines ewes. The average levels of cortisol were significant, at 1.15, 2.86 and 0.52 ?g/dL according to the three collections, being higher after the animal was off the easel at the end of AI. The procedures for performing the transcervical AI technique indicate that stress in the animals produces satisfactory fertility results and a low cost in multiparous ewes of the Santa Ines breed.

Field driven ferromagnetic phase nucleation and propagation from the domain boundaries in antiferromagnetically coupled perpendicular anisotropy films

Energy Technology Data Exchange (ETDEWEB)

Hauet, Thomas; Gunther, Christian M.; Hovorka, Ondrej; Berger, Andreas; Im, Mi-Young; Fischer, Peter; Hellwig, Olav

2008-12-09

We investigate the reversal process in antiferromagnetically coupled [Co/Pt]{sub X-1}/{l_brace}Co/Ru/[Co/Pt]{sub X-1}{r_brace}{sub 16} multilayer films by combining magnetometry and Magnetic soft X-ray Transmission Microscopy (MXTM). After out-of-plane demagnetization, a stable one dimensional ferromagnetic (FM) stripe domain phase (tiger-tail phase) for a thick stack sample (X=7 is obtained), while metastable sharp antiferromagnetic (AF) domain walls are observed in the remanent state for a thinner stack sample (X=6). When applying an external magnetic field the sharp domain walls of the thinner stack sample transform at a certain threshold field into the FM stripe domain wall phase. We present magnetic energy calculations that reveal the underlying energetics driving the overall reversal mechanisms.

The magnetic characterization of Fe doped TiO{sub 2} semiconducting oxide nanoparticles synthesized by sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Yeganeh, M., E-mail: mahboubeh.yeganeh@yahoo.co.uk [Department of Physics, Kosar University of Bojnord, P.O. Box 94104455 (Iran, Islamic Republic of); Shahtahmasebi, N.; Kompany, A. [Department of Physics, Ferdowsi University of Mashhad (Iran, Islamic Republic of); Karimipour, M. [Department of Physics, Vali-e-Asr University of Rafsanjan (Iran, Islamic Republic of); Razavi, F. [Department of Physics, Brock University (Canada); Nasralla, N.H.S. [Electron Microscope and Thin Film Department, Physics Division, 33 El Buhouth st., Dokki, 12622 Giza (Egypt); Šiller, L. [School of Chemical Engineering and Advanced Materials, Newcastle University, NE1 7RU (United Kingdom)

2017-04-15

In this work Fe doped TiO{sub 2} nanoparticles were synthesized at different Fe/Ti molar ratio from 1% to 5% by sol-gel technique. The post annealing of the samples was carried out at T=400, 600, and 800 °C. HRTEM of the samples revealed that the mean size of the nanoparticles increases from about 8 nm to about 100 nm as the annealing temperature increased. SQUID magnetometry of 1% and 5% Fe doped TiO{sub 2} has shown mixed ferromagnetic and paramagnetic phases within the crystal while ferromagnetic order with T{sub c} about 350 K was only observed in 5% Fe:TiO{sub 2} sample annealed at T=800 °C. The oxygen vacancy mediated ferromagnetic (FM) interaction could be responsible for the observed FM.

Decorating Mg/Fe oxide nanotubes with nitrogen-doped carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Cao Yong, E-mail: caoyangel@126.com [Institute of Environment and Municipal Engineering, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Jiao Qingze, E-mail: jiaoqz@bit.edu.cn [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing 100081 (China); Zhao Yun [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing 100081 (China); Dong Yingchao [Materials and Surface Science Institute (MSSI), University of Limerick, Limerick (Ireland)

2011-09-22

Graphical abstract: Highlights: > Mg/Fe oxide nanotubes arrayed parallel to each other were prepared by an AAO template method. > The Mg/Fe oxide nanotubes decorated with CN{sub x} were realized by CVD of ethylenediamine on the outer surface of oxide nanotubes. > The magnetic properties of Mg/Fe oxide nanotubes were highly improved after being decorated. - Abstract: Mg/Fe oxide nanotubes decorated with nitrogen-doped carbon nanotubes (CN{sub x}) were fabricated by catalytic chemical vapor deposition of ethylenediamine on the outer surface of oxide nanotubes. Mg/Fe oxide nanotubes were prepared using a 3:1 molar precursor solution of Mg(NO{sub 3}){sub 2} and Fe(NO{sub 3}){sub 3} and anodic aluminum oxide as the substrate. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The XRD pattern shows that the oxide nanotubes are made up of MgO and Fe{sub 2}O{sub 3}. TEM and SEM observations indicate the oxide nanotubes are arrayed roughly parallel to each other, and the outer surface of oxide nanotubes are decorated with CN{sub x}. XPS results show the nitrogen-doped level in CN{sub x} is about 7.3 at.%. Magnetic measurements with VSM demonstrate the saturated magnetization, remanence and coercivity of oxide nanotubes are obvious improved after being decorated with CN{sub x}.

Comparative study of the magnetic properties of La3Ni2B‧O9 for B‧ = Nb, Taor Sb

Science.gov (United States)

Chin, Chun-Mann; Battle, Peter D.; Blundell, Stephen J.; Hunter, Emily; Lang, Franz; Hendrickx, Mylène; Paria Sena, Robert; Hadermann, Joke

2018-02-01

Polycrystalline samples of La3Ni2NbO9 and La3Ni2TaO9 have been characterised by X-ray and neutron diffraction, electron microscopy, magnetometry and muon spin relaxation (μSR); the latter technique was also applied to La3Ni2SbO9. On the length scale of a neutron diffraction experiment, the six-coordinate sites of the monoclinic perovskite structure are occupied in a 1:1 ordered manner by Ni and a random ⅓Ni/⅔B‧ mixture. Electron microscopy demonstrated that this 1:1 ordering is maintained over microscopic distances, although diffuse scattering indicative of short-range ordering on the mixed site was observed. No magnetic Bragg scattering was observed in neutron diffraction patterns collected from La3Ni2B‧O9 (B‧ = Nb or Ta) at 5 K although in each case μSR identified the presence of static spins below 30 K. Magnetometry showed that La3Ni2NbO9 behaves as a spin glass below 29 K but significant short-range interactions are present in La3Ni2TaO9 below 85 K. The contrasting properties of these compounds are discussed in terms of their microstructure.

Structural and magnetic properties of Nd–Mn substituted Y-type hexaferrites synthesized by microemulsion method

International Nuclear Information System (INIS)

Murtaza, G.; Ahmad, R.; Hussain, T.; Ayub, R.; Ali, Irshad; Khan, Muhammad Azhar; Akhtar, Majid Niaz

2014-01-01

Highlights: • Synthesis via a chemical route microemulsion method. • Samples were characterized with XRD, SEM, AFM, FTIR, Dielectric Measurements and VSM. • Single phase patterns were recorded. • A marked decrease in coercivity has been observed with the substitution of Nd–Mn. • These ferrites are suitable for multi-layer chip components in hyper-frequency. - Abstract: Nd–Mn substituted hexaferrites of composition Sr 2−x Nd x Ni 0.5 Co 1.5 Fe 12−y Mn y O 22 (x = 0.0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30, y = 0.0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75) were synthesized using microemulsion method. The synthesized materials are characterized using different techniques including X-ray diffraction (XRD), scanning electron microscopy(SEM), atomic force microscopy (AFM), Fourier transform Infrared spectroscopy (FTIR), Inductance capacitance resistance (LCR) meter and Vibrating sample magnetic magnetometer (VSM). For all samples, a single Y-type phase was established and the lattice constants have been calculated. XRD patterns reveal the significant increase in line broadening which indicates a decrease of grain size. The samples exhibit well defined crystallization; all of them are hexagonal platelet grains. With the increasing substitution level of Nd–Mn, the average grain diameter decreases. The dielectric constant ε ′ and dielectric loss factor ε″ are found to decrease initially with an increase in frequency and reached a constant value at higher frequency, exhibiting a frequency-independent behavior at higher frequencies. The dielectric loss tangent tanδ was found to decrease with an increase in the frequency. The H c decreases remarkably with increasing Nd and Mn ions content. It was found that the particle size could be effectively decreased and coercivity H c could easily be controlled by varying the concentration (x) without significantly decreasing saturation magnetization

Proxy magnetometry with the Dutch Open Telescope

NARCIS (Netherlands)

Rutten, R.J.; Hammerschlag, R.H.; Sütterlin, P.; Bettonvil, F.C.M.

1999-01-01

Superb movies from the Dutch Open Telescope (DOT) on La Palma have proven the validity of the open concept of this innovative telescope for high-resolution imaging of the solar atmosphere. A five- camera speckle-burst registration system is being installed that should permit consistent and

Modern radio-optical methods in quantum magnetometry

International Nuclear Information System (INIS)

Aleksandrov, Evgenii B; Vershovskii, Anton K

2009-01-01

This paper is an extension of a part of the talk delivered under the more general title 'Narrow spectral lines in fundamental metrology: state of the art, prospects, and problems' at the session of the 90th anniversary of Physics-Uspekhi. The talk reviewed past developments and the current status of the metrology of length, frequency/time, and magnetic fields. The measurement of these quantities currently relies on the high stability of energies of standard transitions between metastable atomic states. Because of space restrictions in the journal, all metrology topics other than the title one were omitted in the present review. (oral issue of the journal 'uspekhi fizicheskikh nauk')

Magnetometry with Low-Resistance Proximity Josephson Junction

Science.gov (United States)

Jabdaraghi, R. N.; Peltonen, J. T.; Golubev, D. S.; Pekola, J. P.

2018-06-01

We characterize a niobium-based superconducting quantum interference proximity transistor (Nb-SQUIPT) and its key constituent formed by a Nb-Cu-Nb SNS weak link. The Nb-SQUIPT and SNS devices are fabricated simultaneously in two separate lithography and deposition steps, relying on Ar ion cleaning of the Nb contact surfaces. The quality of the Nb-Cu interface is characterized by measuring the temperature-dependent equilibrium critical supercurrent of the SNS junction. In the Nb-SQUIPT device, we observe a maximum flux-to-current transfer function value of about 55 nA/Φ_0 in the sub-gap regime of bias voltages. This results in suppression of power dissipation down to a few fW. Low-bias operation of the device with a relatively low probe junction resistance decreases the dissipation by up to two orders of magnitude compared to a conventional device based on an Al-Cu-Al SNS junction and an Al tunnel probe (Al-SQUIPT).

Removal of Cu(II) metal ions from aqueous solution by amine functionalized magnetic nanoparticles

Science.gov (United States)

Kothavale, V. P.; Karade, V. C.; Waifalkar, P. P.; Sahoo, Subasa C.; Patil, P. S.; Patil, P. B.

2018-04-01

The adsorption behavior of Cu(II) metal cations was investigated on the amine functionalized magnetic nanoparticles (MNPs). TheMNPs were synthesized by thesolvothermal method and functionalized with (3-Aminopropyl)triethoxysilane (APTES). MNPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM). The MNPs have pure magnetite phase with particle size around 10-12 nm. MNPs exhibits superparamagnetic behavior with asaturation magnetization of 68 emu/g. The maximum 38 % removal efficiency was obtained for Cu(II) metal ions from the aqueous solution.

Activity Based Costing in Value Stream Mapping

Directory of Open Access Journals (Sweden)

S. S. Abuthakeer

2010-12-01

Full Text Available This paper attempts to integrate Value Stream Map (VSM with the cost aspects. A value stream map provides a blueprint for implementing lean manufacturing concepts by illustrating information and materials flow in a value stream. The objective of the present work is to integrate the various cost aspects. The idea is to introduce a cost line, which enhances the clarity in decision making. The redesigned map proves to be effective in highlighting the improvement areas, in terms of quantitative data. TAKT time calculation is carried out to set the pace of production. Target cost is set as a bench mark for product cost. The results of the study indicates that implementing VSM led to reduction in the following areas: processing lead time by 34%, processing cycle time was reduced by 35%, Inventory level by 66% and product cost from Rs 137 to Rs 125. It was found that adopting VSM in a small scale industry can make significant improvements.

Biogas production generated through continuous digestion of natural and cultivated seaweeds with dairy slurry.

Science.gov (United States)

Tabassum, Muhammad Rizwan; Wall, David M; Murphy, Jerry D

2016-11-01

The technical feasibility of long term anaerobic mono-digestion of two brown seaweeds, and co-digestion of both seaweeds with dairy slurry was investigated whilst increasing the organic loading rate (OLR). One seaweed was natural (L. digitata); the second seaweed (S. Latissima) was cultivated. Higher proportions of L. digitata in co-digestion (66.6%) allowed the digester to operate more efficiently (OLR of 5kgVSm(-3)d(-1) achieving a specific methane yield (SMY) of 232LCH4kg(-1)VS) as compared to lower proportions (33.3%). Co-digestion of 66.6% cultivated S. latissima, with dairy slurry allowed a higher SMY of 252LCH4kg(-1)VS but at a lower OLR of 4kgVSm(-3)d(-1). Optimum conditions for mono-digestion of both seaweeds were effected at 4kgVSm(-3)d(-1). Chloride concentrations increased to high levels in the digestion of both seaweeds but were not detrimental to operation. Copyright © 2016 Elsevier Ltd. All rights reserved.

An evaluation of parent-produced video self-modeling to improve independence in an adolescent with intellectual developmental disorder and an autism spectrum disorder: a controlled case study.

Science.gov (United States)

Allen, Keith D; Vatland, Christopher; Bowen, Scott L; Burke, Raymond V

2015-07-01

We evaluated a parent-created video self-modeling (VSM) intervention to improve independence in an adolescent diagnosed with Intellectual Developmental Disorder (IDD) and Autism Spectrum Disorder (ASD). In a multiple baseline design across routines, a parent and her 17-year-old daughter created self-modeling videos of three targeted routines needed for independence in the community. The parent used a tablet device with a mobile app called "VideoTote" to produce videos of the daughter performing the targeted routines. The mobile app includes a 30-s tutorial about making modeling videos. The parent and daughter produced and watched a VSM scene prior to performing each of the three routines in an analogue community setting. The adolescent showed marked, immediate, and sustained improvements in performing each routine following the production and implementation of the VSM. Performance was found to generalize to the natural community setting. Results suggest that parents can use available technology to promote community independence for transition age individuals. © The Author(s) 2015.

Study of magnetic and electrical properties of La doped Mn-Zn nanoferrites synthesized by co-precipitation technique

International Nuclear Information System (INIS)

Panwar, Neena; Thakur, Atul; Thakur, Preeti

2013-01-01

Lanthanum manganese zinc ferrite powder of the composition Mn 0.4 Zn 0.6 La 0.4 Fe 1.6 O 4 were synthesized via co-precipitation technique. Metallic chlorides of manganese, zinc and iron in which Lanthanum is doped were taken. Sodium hydroxide (NaOH) base was used as precipitant agent. The calcinations (presintering) were performed at 700℃ for 3h and sintering at different temperatures 900℃, 850℃, 800℃ also for 3h. The structural investigation of the prepared sample was performed with X-ray diffraction (XRD) and scanning electron microscope (SEM). For studying magnetic properties vibrating sample magnetometer (VSM) are used. Electrical properties were studied by DC resistivity set up. (author)

Transformation of Goethite to Hematite Nanocrystallines by High Energy Ball Milling

Directory of Open Access Journals (Sweden)

O. M. Lemine

2014-01-01

Full Text Available α-Fe2O3 nanocrystallines were prepared by direct transformation via high energy ball milling treatment for α-FeOOH powder. X-ray diffraction, Rietveld analysis, TEM, and vibrating sample magnetometer (VSM are used to characterize the samples obtained after several milling times. Phase identification using Rietveld analysis showed that the goethite is transformed to hematite nanocrystalline after 40 hours of milling. HRTEM confirm that the obtained phase is mostly a single-crystal structure. This result suggested that the mechanochemical reaction is an efficient way to prepare some iron oxides nanocrystallines from raw materials which are abundant in the nature. The mechanism of the formation of hematite is discussed in text.

Magnetic behavior of biosynthesized Co_3O_4 nanoparticles

International Nuclear Information System (INIS)

Diallo, A.; Doyle, T.B.; Mothudi, B.M.; Manikandan, E.

2017-01-01

This contribution reports for the 1st time on the magnetic behavior of CO_3O_4 nanoparticles synthesized by a “green” process using an Aspalathus linearis’ leaves natural extract. More accurately magnetic behavior of CO_3O_4 nanoparticles successfully biosynthesized was investigated using vibrating sample magnetometer. The magnetization behavior for the samples manifests a combination of size dependent antiferromagnetic and paramagnetic behaviors, respectively, for the core and shell of the nanoparticles. - Highlights: • 1"s"t report on magnetic behavior of Co3O4 nanoparticles via Aspalathus linearis. • Co_3O_4 nanoparticles manifest size-dependent antiferromagnetic & paramagnetic behaviors. • Antiferromagnetic & paramagnetic behaviors were confirmed by VSM.

Magnetic behavior of biosynthesized Co{sub 3}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Diallo, A., E-mail: abdoulayediallosn@gmail.com [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation,1 Old Faure road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); Centre for Nano Science and Nanotechnology, K.S. Rangasamy College of Technology, Tiruchengode 63721, Tamil Nadu (India); Laboratoire de Photonique et de Nano-Fabrication, Faculté des sciences et Techniques, Université Cheikh Anta Diop de Dakar (UCAD), B.P. 25114, Dakar-Fann Dakar (Senegal); Doyle, T.B. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation,1 Old Faure road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4001 (South Africa); Mothudi, B.M.; Manikandan, E. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation,1 Old Faure road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); and others

2017-02-15

This contribution reports for the 1st time on the magnetic behavior of CO{sub 3}O{sub 4} nanoparticles synthesized by a “green” process using an Aspalathus linearis’ leaves natural extract. More accurately magnetic behavior of CO{sub 3}O{sub 4} nanoparticles successfully biosynthesized was investigated using vibrating sample magnetometer. The magnetization behavior for the samples manifests a combination of size dependent antiferromagnetic and paramagnetic behaviors, respectively, for the core and shell of the nanoparticles. - Highlights: • 1{sup st} report on magnetic behavior of Co3O4 nanoparticles via Aspalathus linearis. • Co{sub 3}O{sub 4} nanoparticles manifest size-dependent antiferromagnetic & paramagnetic behaviors. • Antiferromagnetic & paramagnetic behaviors were confirmed by VSM.

Synthesis of ferrofluids based on cobalt ferrite nanoparticles: Influence of reaction time on structural, morphological and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Amirabadizadeh, Ahmad; Salighe, Zohre; Sarhaddi, Reza, E-mail: reza.sarhaddi@birjand.ac.ir; Lotfollahi, Zahra

2017-07-15

Highlights: • Ferrofluids based on cobalt ferrite nanoparticles were synthesized by co-precipitation method. • The crystallite and particle size of cobalt ferrite can be controlled effectively by reaction time. • The ferrofluids have lower values of saturation magnetization and coercivity as compared to nanoparticles. • By increasing the size of nanoparticles, the narrower and sharper spikes of ferrofluids are formed. - Abstract: In this work, for first time the ferrofluids based on the cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles were prepared by the co-precipitation method at different reaction times (0.5–6.5 h). Crystal structure, morphology and magnetic properties of the cobalt ferrite nanoparticles and the ferrofluids based on the nanoparticles were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and vibrating sample magnetometer (VSM). The XRD patterns of CoFe{sub 2}O{sub 4} nanoparticles synthesized at different reaction times indicated that all samples are single phase in accordance with inverse cubic spinel structure with space group Fd-3m, and no impurity phase was observed. By increasing the reaction time to 3.5 h, the lattice parameter and the average crystallites size increased and then afterwards decreased by increasing the reaction time. The microscopic studies indicated the formation of nanosized particles with nearly spherical in shape, whereas the average particle size for all samples is found to be less than 50 nm. The results of VSM also showed that the saturation magnetization and coercivity field of the cobalt ferrite nanoparticles and the ferrofluids were influenced by reaction time, whereas the ferrofluids have lower values of magnetic parameters than that of nanoparticles.

FC and ZFC magnetic properties of ferro-spinels (MFe2O4) prepared by solution-combustion method

Science.gov (United States)

Aravind, G.; Kumar, R. Vijaya; Nathaniyal, V.; Rambabu, T.; Ravinder, D.

2017-07-01

Magnetic ferro-spinels MFe2O4 (M= Co and Ni) prepared by citrate-gel solution combustion method using metal nitrates with low sintering temperature (500°C). From the XRD and TEM studies confirm that a nano crystalline nature of the prepared samples. Field Cooled (FC) and Zero Field Cooled (ZFC) magnetic studies of the prepared ferro-spinels are measured by using vibrating sample magnetometer (VSM). The resultant magnetization of the prepared samples as a function of an applied magnetic field 10 T was measured at two different temperatures 5 K and 310 K. Field Cooled (FC) and Zero Field Cooled (ZFC) magnetization measurements under an applied field of 100 Oe and 1000 Oe in the temperature range of 5-375 K were carried out, which shows the blocking temperature of these two samples at around 350 K.

The crystalline and magnetic properties of Zn doped strontium Z-type hexaferrite synthesized by polymerizable complex method

Directory of Open Access Journals (Sweden)

Jung Tae Lim

2017-05-01

Full Text Available Polycrystalline samples of Sr3Co2-xZnxFe24O41 (x = 0.0, 0.5, 1.0, 1.5, 2.0 were synthesized by a polymerizable complex method. The crystallographic, and magnetic properties of samples were investigated using x-ray diffractometer (XRD, vibrating sample magnetometer (VSM, and Mössbauer spectroscopy. The crystal structures of all samples were determined to be hexagonal with the space group P63/mmc. The hysteresis curves under 10 kOe at 295 K showed that all samples were not saturated due to the high planar anisotropy of Sr ions. In addition, the coercivity (Hc of samples decreased with increasing Zn ion contents. Mössbauer spectra of all samples were obtained at 295 K, and least-squares fitted below TC as six distinguishable sextets (4fIV, 4fIV*, 12kVI*, 4fVI*+ 4eIV, 12kVI, and 2dV + 2aVI + 4fVI + 4eVI.

Boundaries of the instability region on the HT diagram of Nb thin films

International Nuclear Information System (INIS)

Colauto, F; Ortiz, W A; Patino, E J; Blamire, M G

2008-01-01

Catastrophic penetration of magnetic fields in the form of dendrites has been reported for some specimens of superconducting thin films in the perpendicular geometry. Such behavior is related essentially to the capability of the sample and substrate to assimilate heat generated by vortex motion. In order to map the region where instabilities occur, we have employed dc magnetometry, which has been shown to be an efficient technique for this purpose. This catastrophic regime ceases at temperatures above 4 K. For the sample studied, fluctuations have been detected on virgin curves of the magnetic moment as a function of the applied field. Our systematic study shows that there is a threshold line on the HT diagram, which encompasses the region where the magnetic response fluctuates

Boundaries of the instability region on the HT diagram of Nb thin films

Energy Technology Data Exchange (ETDEWEB)

Colauto, F; Ortiz, W A [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, C P 676, 13565-905, Sao Carlos, SP (Brazil); Patino, E J; Blamire, M G [Department of Materials Science, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)], E-mail: fcolauto@df.ufscar.br

2008-04-01

Catastrophic penetration of magnetic fields in the form of dendrites has been reported for some specimens of superconducting thin films in the perpendicular geometry. Such behavior is related essentially to the capability of the sample and substrate to assimilate heat generated by vortex motion. In order to map the region where instabilities occur, we have employed dc magnetometry, which has been shown to be an efficient technique for this purpose. This catastrophic regime ceases at temperatures above 4 K. For the sample studied, fluctuations have been detected on virgin curves of the magnetic moment as a function of the applied field. Our systematic study shows that there is a threshold line on the HT diagram, which encompasses the region where the magnetic response fluctuates.

Superconductivity in LaCu 6 and possible applications

Science.gov (United States)

Herrmannsdörfer, Thomas; Pobell, Frank; Sebek, Josef; Svoboda, Pavel

2003-05-01

We have measured the ac susceptibility and resistivity of highly pure samples of the intermetallic compound LaCu6 down to ultralow temperatures. We have prepared the samples by arc melting of stoichiometric amounts of 99.99% La and 99.9999% Cu in a water-cooled copper crucible under Ar protective atmosphere and analysed them by X-ray diffraction and SQUID magnetometry. At T⩽Tc=0.16 K we observe a superconducting transition. Due to the manifold physical properties of isostructural ReCu6 compounds (e.g. RE = Ce: heavy fermion system, RE=Pr: hyperfine enhanced nuclear spin system, RE = Nd: electronic antiferromagnet), numerous studies of interplay phenomena may become possible in the quasibinary compounds RE1-xLaxCu6, respectively.

Synthesis and characterization of diethylenetriaminepentaacetic acid-chitosan-coated cobalt ferrite core/shell nanostructures

Energy Technology Data Exchange (ETDEWEB)

Runhua, Qin [Department of Physics, North University of China, Taiyuan 030051 (China); National Special Superfine Powder Engineering Research Center, Nanjing University Science and Technology, Xiaolingwei 200, Nanjing 210094 (China); Li Fengsheng, E-mail: qinrunh@126.com [National Special Superfine Powder Engineering Research Center, Nanjing University Science and Technology, Xiaolingwei 200, Nanjing 210094 (China); Wei, Jiang; Mingyue, Chen [National Special Superfine Powder Engineering Research Center, Nanjing University Science and Technology, Xiaolingwei 200, Nanjing 210094 (China)

2010-08-01

Special diethylenetriaminepentaacetic acid (DTPA)-chitosan-coated cobalt ferrite core/shell nanoparticles have been synthesized via a novel zero-length emulsion crosslinking process and characterized via crosslinking degree, simultaneous thermogravimetric analysis and differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared spectrometer, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and vibration sample magnetometry. The experimental results showed that the CoFe{sub 2}O{sub 4} nanoparticles were really encapsulated with a DTPA-chitosan hybrid layer and the nanocomposites were proved to be nearly superparamagnetic with saturation magnetization of 26.6 emu g{sup -1}.

Magnetic properties of melt-spun FeMnAlB alloys

International Nuclear Information System (INIS)

Betancourt, I.; Nava, F.

2007-01-01

Magnetic properties of melt spun Fe 89-x Mn 11 Al x (x=2,4,8,15) and Fe 87-y Mn 11 Al 2 By(y=6,8,10) alloy series were studied by vibrating sample magnetometry and complex permeability measurements. The saturation magnetization exhibited an initial high value of 210emu/g followed by a decreasing tendency with increasing Al and B additions (up to 139emu/g). On the other hand, the initial permeability showed variations within the range 1000-2000, whereas the relaxation frequency displayed a maximum of 2MHz for the 4at% Al alloy

Probing Spin Crossover in a Solution by Paramagnetic NMR Spectroscopy.

Science.gov (United States)

Pavlov, Alexander A; Denisov, Gleb L; Kiskin, Mikhail A; Nelyubina, Yulia V; Novikov, Valentin V

2017-12-18

Spin transitions in spin-crossover compounds are now routinely studied in the solid state by magnetometry; however, only a few methods exist for studies in solution. The currently used Evans method, which relies on NMR spectroscopy to measure the magnetic susceptibility, requires the availability of a very pure sample of the paramagnetic compound and its exact concentration. To overcome these limitations, we propose an alternative NMR-based technique for evaluating spin-state populations by only using the chemical shifts of a spin-crossover compound; those can be routinely obtained for a solution that contains unknown impurities and paramagnetic admixtures or is contaminated otherwise.

Activation energy of time-dependent martensite formation in steel

DEFF Research Database (Denmark)

Villa, Matteo; Somers, Marcel A. J.

2018-01-01

The kinetics of {557}γ lath martensite formation in (wt%) 17Cr-7Ni-1Al-0.09C and 15Cr-7Ni-2Mo-1Al-0.08C steels was assessed with magnetometry at sub-zero Celsius temperatures. Samples were cooled to 77 K by immersion in boiling nitrogen to suppress martensite formation. Thereafter, thermally...... applied to evaluate the data available in the literature. The overall analysis showed that EA varies in the range 2–27 kJ mol−1 and increases logarithmically with the total fraction of interstitials in the steel....

Nanoscale magnetic field mapping with a single spin scanning probe magnetometer

Energy Technology Data Exchange (ETDEWEB)

Rondin, L.; Tetienne, J.-P.; Spinicelli, P.; Roch, J.-F.; Jacques, V. [Laboratoire de Photonique Quantique et Moleculaire, Ecole Normale Superieure de Cachan and CNRS UMR 8537, 94235 Cachan Cedex (France); Dal Savio, C.; Karrai, K. [Attocube systems AG, Koeniginstrasse 11A RGB, Munich 80539 (Germany); Dantelle, G. [Laboratoire de Physique de la Matiere Condensee, Ecole Polytechnique and CNRS UMR 7643, 91128 Palaiseau (France); Thiaville, A.; Rohart, S. [Laboratoire de Physique des Solides, Universite Paris-Sud and CNRS UMR 8502, 91405 Orsay (France)

2012-04-09

We demonstrate quantitative magnetic field mapping with nanoscale resolution, by applying a lock-in technique on the electron spin resonance frequency of a single nitrogen-vacancy defect placed at the apex of an atomic force microscope tip. In addition, we report an all-optical magnetic imaging technique which is sensitive to large off-axis magnetic fields, thus extending the operation range of diamond-based magnetometry. Both techniques are illustrated by using a magnetic hard disk as a test sample. Owing to the non-perturbing and quantitative nature of the magnetic probe, this work should open up numerous perspectives in nanomagnetism and spintronics.

Synthesis and Characterization of Holmium-Doped Iron Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

Maarten Bloemen

2014-02-01

Full Text Available Rare earth atoms exhibit several interesting properties, for example, large magnetic moments and luminescence. Introducing these atoms into a different matrix can lead to a material that shows multiple interesting effects. Holmium atoms were incorporated into an iron oxide nanoparticle and the concentration of the dopant atom was changed in order to determine its influence on the host crystal. Its magnetic and magneto-optical properties were investigated by vibrating sample magnetometry and Faraday rotation measurements. The luminescent characteristics of the material, in solution and incorporated in a polymer thin film, were probed by fluorescence experiments.

Radiolabeling hydroxyapatite nanorods as theranostic agents for osteosarcoma and bone metastases; Nanobastões de hidroxiapatita radiomarcados como agentes teranósticos para osteossarcomas e metastases ósseas

Energy Technology Data Exchange (ETDEWEB)

Cipreste, Marcelo Fernandes

2017-07-01

characterized by several techniques such as X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FTIR) and X-ray fluorescence (EDX), elemental analysis (CHN), X-ray diffraction (XRD) with Rietveld refinement, electron microscopy images, nitrogen adsorption analysis, X-ray absorption fine structure spectroscopy (XAFS), thermogravimetric analysis, vibration sample magnetometry (VSM). All these characterizations were performed in order to study the general properties of these materials and the stability of the interactions between HA, FA, Gd and CuO. In addition, the biocompatibility of this system was tested on fibroblast cells and cytotoxicity was tested on osteosarcoma cells. The results indicated that the functionalization of hydroxyapatite with folic acid is possible and forms a stable interaction, the doping process of HA with Gd was successful as well as the synthesis of the Hydroxyapatite/Tenorite nanocomposite and the biological tests suggest that the materials are biocompatible and have the potential to treat osteosarcoma. (author)

Radiolabeling hydroxyapatite nanorods as theranostic agents for osteosarcoma and bone metastases

International Nuclear Information System (INIS)

Cipreste, Marcelo Fernandes

2017-01-01

by several techniques such as X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FTIR) and X-ray fluorescence (EDX), elemental analysis (CHN), X-ray diffraction (XRD) with Rietveld refinement, electron microscopy images, nitrogen adsorption analysis, X-ray absorption fine structure spectroscopy (XAFS), thermogravimetric analysis, vibration sample magnetometry (VSM). All these characterizations were performed in order to study the general properties of these materials and the stability of the interactions between HA, FA, Gd and CuO. In addition, the biocompatibility of this system was tested on fibroblast cells and cytotoxicity was tested on osteosarcoma cells. The results indicated that the functionalization of hydroxyapatite with folic acid is possible and forms a stable interaction, the doping process of HA with Gd was successful as well as the synthesis of the Hydroxyapatite/Tenorite nanocomposite and the biological tests suggest that the materials are biocompatible and have the potential to treat osteosarcoma. (author)

The Mossbauer spectra of carbon nanotubes synthesize using ferrite catalyst

International Nuclear Information System (INIS)

Zhang Haiyan; Lin Jiapeng; Peng Zuxiong; Zeng Guoxun; Pang Jinshan; Chen Yiming

2009-01-01

The ferrite powder with honeycombed structure obtained by chemical combustion was used as catalyst to synthesize multi-walled carbon nanotubes by chemical vapor deposition. The magnetic components and characters of the the carbon nanotubes synthesized were investigated by X-ray diffraction (XRD), Mossbauer spectra and vibrating-sample magnetometer (VSM). The ferric components of the carbon nanotubes samples can be identified by Mossbauer spectra. The Mossbauer spectra of carbon nanotubes sample after purification contains two ferromagnetic sextet components corresponding to α-Fe species and Fe 3 C (cementite) species. While the Mossbauer spectra of the carbon nanotubes sample before purification contains three ferromagnetic sextet components corresponding to α-Fe species, Fe 3 C species and γ-Fe 2 O 3 . The saturation magnetization intensity Ms of carbon nanotubes sample after purification is decreased from 46.61 to 2.94 emu/g, but the coercive force increasd and reached 328Oe.

Gd doping induced weak ferromagnetic ordering in ZnS nanoparticles synthesized by low temperature co-precipitation technique

Energy Technology Data Exchange (ETDEWEB)

Kaur, Palvinder [Department of Physics, Punjabi University, Patiala, Punjab, 147002 (India); Kumar, Sanjeev, E-mail: sanjeev04101977@gmail.com [Applied Science Department, PEC University of Technology, Chandigarh, 160012 (India); Chen, Chi-Liang, E-mail: chen.cl@nsrrc.org.tw [National Synchrotron Radiation Research Center (NSRRC), Hsinchu, 30076, Taiwan (China); Yang, Kai-Siang [National Synchrotron Radiation Research Center (NSRRC), Hsinchu, 30076, Taiwan (China); Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Wei, Da-Hua [Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Dong, Chung-Li [Department of Physics, Tamkang University, Tamsui, Taiwan (China); Srivastava, C. [Materials Engineering Department, Indian Institute of Science, Bangalore, 560012 (India); Rao, S.M. [Department of Physics, Punjabi University, Patiala, Punjab, 147002 (India); Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan (China)

2017-01-15

Zn{sub 1−x}Gd{sub x}S nanoparticles with Gd concentration x = 0.00, 0.02 and 0.04 were synthesized by the chemical co-precipitation technique using thioglycerol as capping agent. X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, X-ray absorption near-edge structure (XANES) and vibrating sample magnetometer (VSM) were employed to characterize the as synthesized Gd doped ZnS nanoparticles. XRD and TEM studies show the formation of cubic ZnS nanoparticles with an average size in the range 5–10 nm. The doping did not alter the phase of the ZnS. The PL spectra of doped ZnS nanoparticles showed the presence of sulphur vacancies in the lattice. XANES of Gd doped ZnS nanoparticles depicts spectral changes may arise from charge transfer between host Zn and dopant Gd ions. A VSM study shows that the weak ferromagnetic behaviour increases with increase in Gd doping ZnS nanoparticles. - Highlights: • Gd doped ZnS nanoparticles synthesized using co-precipitation technique. • PL studies depict sulphur and zinc vacancies in Gd doped ZnS nanoparticles. • XANES studies depict the charge transfer between host Zn and dopant Gd ions. • Room temperature weak ferromagnetism is observed in Gd doped ZnS nanoparticles.

Facile synthesis of monodisperse superparamagnetic Fe{sub 3}O{sub 4}/PMMA composite nanospheres with high magnetization

Energy Technology Data Exchange (ETDEWEB)

Lan Fang; Liu Kexia; Jiang Wen; Zeng Xiaobo; Wu Yao; Gu Zhongwei, E-mail: Yaowu_amanda@126.com, E-mail: zwgu@scu.edu.cn [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064 (China)

2011-06-03

Monodisperse superparamagnetic Fe{sub 3}O{sub 4}/polymethyl methacrylate (PMMA) composite nanospheres with high saturation magnetization were successfully prepared by a facile novel miniemulsion polymerization method. The ferrofluid, MMA monomer and surfactants were co-sonicated and emulsified to form stable miniemulsion for polymerization. The samples were characterized by DLS, TEM, FTIR, XRD, TGA and VSM. The diameter of the Fe{sub 3}O{sub 4}/PMMA composite nanospheres by DLS was close to 90 nm with corresponding polydispersity index (PDI) as small as 0.099, which indicated that the nanospheres have excellent homogeneity in aqueous medium. The TEM results implied that the Fe{sub 3}O{sub 4}/PMMA composite nanospheres had a perfect core-shell structure with about 3 nm thin PMMA shells, and the core was composed of many homogeneous and closely packed Fe{sub 3}O{sub 4} nanoparticles. VSM and TGA showed that the Fe{sub 3}O{sub 4}/PMMA composite nanospheres with at least 65% high magnetite content were superparamagnetic, and the saturation magnetization was as high as around 39 emu g{sup -1} (total mass), which was only decreased by 17% compared with the initial bare Fe{sub 3}O{sub 4} nanoparticles.

Gd doping induced weak ferromagnetic ordering in ZnS nanoparticles synthesized by low temperature co-precipitation technique

International Nuclear Information System (INIS)

Kaur, Palvinder; Kumar, Sanjeev; Chen, Chi-Liang; Yang, Kai-Siang; Wei, Da-Hua; Dong, Chung-Li; Srivastava, C.; Rao, S.M.

2017-01-01

Zn_1_−_xGd_xS nanoparticles with Gd concentration x = 0.00, 0.02 and 0.04 were synthesized by the chemical co-precipitation technique using thioglycerol as capping agent. X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, X-ray absorption near-edge structure (XANES) and vibrating sample magnetometer (VSM) were employed to characterize the as synthesized Gd doped ZnS nanoparticles. XRD and TEM studies show the formation of cubic ZnS nanoparticles with an average size in the range 5–10 nm. The doping did not alter the phase of the ZnS. The PL spectra of doped ZnS nanoparticles showed the presence of sulphur vacancies in the lattice. XANES of Gd doped ZnS nanoparticles depicts spectral changes may arise from charge transfer between host Zn and dopant Gd ions. A VSM study shows that the weak ferromagnetic behaviour increases with increase in Gd doping ZnS nanoparticles. - Highlights: • Gd doped ZnS nanoparticles synthesized using co-precipitation technique. • PL studies depict sulphur and zinc vacancies in Gd doped ZnS nanoparticles. • XANES studies depict the charge transfer between host Zn and dopant Gd ions. • Room temperature weak ferromagnetism is observed in Gd doped ZnS nanoparticles.

Gd{sup 3+} doped Mn-Zn soft ferrite nanoparticles: Superparamagnetism and its correlation with other physical properties

Energy Technology Data Exchange (ETDEWEB)

Thakur, Prashant; Sharma, Rohit; Sharma, Vineet; Barman, P.B. [Department of Physics & Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 (India); Kumar, Manoj [Department of Physics & Materials Science, Jaypee Institute of Information Technology, Noida 201307 (India); Barman, Dipto [Gwangju Institute of Science & Technology, Gwangju (Korea, Republic of); Department of Computer Science & Engineering, Jaypee University of Information Technology, Waknaghat, Solan, Himachap Pradesh 173234 (India); Katyal, S.C. [Department of Physics & Materials Science, Jaypee Institute of Information Technology, Noida 201307 (India); Sharma, Pankaj, E-mail: pankaj.sharma@juit.ac.in [Department of Physics & Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 (India)

2017-06-15

Highlights: • Superparamagnetic nanoparticles of Gd doped Mn-Zn spinel ferrites synthesized by co-precipitation. • XRD and FTIR studies justify the formation of cubical spinel structure. • Maximum saturation magnetization and magnetic moment at x = 0.025. • PL spectra shows blue shift for x = 0.025, 0.075 and may be attributed to quantum confinement. - Abstract: Superparamagnetic nanoparticles are very important in biomedicine due to their various applications like drug delivery, gene delivery in the body and also used for hyperthermia. In the present work, superparamagnetic nanoparticles of Mn{sub 0.5}Zn{sub 0.5}Gd{sub x}Fe{sub 2-x}O{sub 4} (x = 0, 0.025, 0.050, 0.075, 0.1) ferrites have been prepared by co-precipitation method. Thorough characterizations (XRD, FTIR, FE-SEM, EDS, VSM and fluorescence spectroscopy) have proved the formation of cubical spinel superparamagnetic nanoparticles of soft ferrites. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. With the addition of Gd{sup 3+} nanoparticles have shown the superparamagnetism at room temperature confirmed by VSM analysis. Photoluminescence (PL) spectra shows a blue shift (for x = 0.025, 0.075) which may be due to quantum confinement.

A novel tarantula toxin stabilizes the deactivated voltage sensor of bacterial sodium channel.

Science.gov (United States)

Tang, Cheng; Zhou, Xi; Nguyen, Phuong Tran; Zhang, Yunxiao; Hu, Zhaotun; Zhang, Changxin; Yarov-Yarovoy, Vladimir; DeCaen, Paul G; Liang, Songping; Liu, Zhonghua

2017-07-01

Voltage-gated sodium channels (Na V s) are activated by transiting the voltage sensor from the deactivated to the activated state. The crystal structures of several bacterial Na V s have captured the voltage sensor module (VSM) in an activated state, but structure of the deactivated voltage sensor remains elusive. In this study, we sought to identify peptide toxins stabilizing the deactivated VSM of bacterial Na V s. We screened fractions from several venoms and characterized a cystine knot toxin called JZTx-27 from the venom of tarantula Chilobrachys jingzhao as a high-affinity antagonist of the prokaryotic Na V s Ns V Ba (nonselective voltage-gated Bacillus alcalophilus ) and NaChBac (bacterial sodium channel from Bacillus halodurans ) (IC 50 = 112 nM and 30 nM, respectively). JZTx-27 was more efficacious at weaker depolarizing voltages and significantly slowed the activation but accelerated the deactivation of Ns V Ba, whereas the local anesthetic drug lidocaine was shown to antagonize Ns V Ba without affecting channel gating. Mutation analysis confirmed that JZTx-27 bound to S3-4 linker of Ns V Ba, with F98 being the critical residue in determining toxin affinity. All electrophysiological data and in silico analysis suggested that JZTx-27 trapped VSM of Ns V Ba in one of the deactivated states. In mammalian Na V s, JZTx-27 preferably inhibited the inactivation of Na V 1.5 by targeting the fourth transmembrane domain. To our knowledge, this is the first report of peptide antagonist for prokaryotic Na V s. More important, we proposed that JZTx-27 stabilized the Ns V Ba VSM in the deactivated state and may be used as a probe to determine the structure of the deactivated VSM of Na V s.-Tang, C., Zhou, X., Nguyen, P. T., Zhang, Y., Hu, Z., Zhang, C., Yarov-Yarovoy, V., DeCaen, P. G., Liang, S., Liu, Z. A novel tarantula toxin stabilizes the deactivated voltage sensor of bacterial sodium channel. © FASEB.

Effect of Mikania glomerata (Asteraceae leaf extract combined with anti-venom serum on experimental Crotalus durissus (Squamata: Viperidae envenomation in rats

Directory of Open Access Journals (Sweden)

Rafael Stuani Floriano

2009-12-01

Full Text Available Crotalic envenomation represents the highest number of deaths when compared to other snakebite envenomations of medical interest. Crotalic venom has important characteristics such as neurotoxicity, myotoxicity, nephrotoxicity, and clotting and hemolytic action. We evaluated the clinical and laboratory aspects of Crotalus durissus terrificus experimental envenomation in Wistar rats treated with antivenom and the aqueous extract of the plant Mikania glomerata. The animals were divided into three groups: Group C (control; Group VS-venom and antivenom; Group VSM-venom, antivenom and aqueous extract of M. glomerata. Crotalic poison caused clinical and laboratory alterations in Wistar mice. Significant linical alterations were: temperature decrease, edema in the venom inoculated member, sedation and a locomotion decrease in groups VS and VSM when compared with group C. A faster recovery from sedation was observed only for animals of group VSM when compared to VS. There was an increase in the number of leukocytes, neutrophils and creatine kinase in the VS and VSM groups, compared to group C. Wistar rats showed a high resistance to crotalic venom. Additional studies with different doses, time of treatment, different administration methods and histopathological and immunological studies are necessary to understand the action of M. glomerata in crotalic accidents. Rev. Biol. Trop. 57 (4: 929-937. Epub 2009 December 01.El envenamiento crotálico representa el número más alto de muertes cuando es comparado con envenenamientos por mordeduras de otras serpientes de interés médico. El veneno crotálico tiene importantes características de acción neurotóxica, miotoxicidad, nefrotoxicidad, coagulación y acción hemolítica. Este trabajo evaluó los aspectos clínicos y de laboratorio del envenenamiento experimental con el veneno de la serpiente Crotalus durissus terrificus en las ratas Wistar tratadas con suero antiofídico y extracto acuoso de M

Sample size estimation and sampling techniques for selecting a representative sample

Directory of Open Access Journals (Sweden)

Aamir Omair

2014-01-01

Full Text Available Introduction: The purpose of this article is to provide a general understanding of the concepts of sampling as applied to health-related research. Sample Size Estimation: It is important to select a representative sample in quantitative research in order to be able to generalize the results to the target population. The sample should be of the required sample size and must be selected using an appropriate probability sampling technique. There are many hidden biases which can adversely affect the outcome of the study. Important factors to consider for estimating the sample size include the size of the study population, confidence level, expected proportion of the outcome variable (for categorical variables/standard deviation of the outcome variable (for numerical variables, and the required precision (margin of accuracy from the study. The more the precision required, the greater is the required sample size. Sampling Techniques: The probability sampling techniques applied for health related research include simple random sampling, systematic random sampling, stratified random sampling, cluster sampling, and multistage sampling. These are more recommended than the nonprobability sampling techniques, because the results of the study can be generalized to the target population.

Ultrasound-assisted fabrication of a biocompatible magnetic hydroxyapatite.

Science.gov (United States)

Zhou, Gang; Song, Wei; Hou, Yongzhao; Li, Qing; Deng, Xuliang; Fan, Yubo

2014-10-01

This work describes the fabrication and characterization of a biocompatible magnetic hydroxyapatite (HA) using an ultrasound-assisted co-precipitation method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) were used to characterize the structure and chemical composition of the produced samples. The M-H loops of synthesized materials were traced using a vibrating sample magnetometer (VSM) and the biocompatibility was evaluated by cell culture and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Furthermore, in vivo histopathological examinations were used to evaluate the potential toxicological effects of Fe₃O₄-HA composites on kidney of SD rats injected intraperitoneally with Fe₃O₄-HA particles. The results showed that magnetic iron oxide particles first replace OH ions of HA, which are parallel to the c axis, and then enter the HA crystal lattice which produces changes in the crystal surface of HA. Chemical bond interaction was observed between PO₄³⁻ groups of HA and iron ions of Fe₃O₄. The saturation magnetization (MS ) of Fe₃O₄-HA composites was 46.36 emu/g obtained from VSM data. Cell culture and MTT assays indicated that HA could affect the growth and proliferation of HEK-293 cells. This Fe₃O₄-HA composite produced no negative effects on cell morphology, viability, and proliferation and exhibited remarkable biocompatibility. Moreover, no inflammatory cell infiltration was observed in kidney histopathology slices. Therefore, this study succeeds to develop a Fe₃O₄-HA composite as a prospective biomagnetic material for future applications. © 2013 Wiley Periodicals, Inc.

An Application of Value Stream Mapping in Production Flow Analysis: A lean approach in An Automotive Industry

Directory of Open Access Journals (Sweden)

Krushnaraj Bodana

2016-08-01

Full Text Available Lean manufacturing deals with a manufacturing process improvement based on the fundamental goal of Toyota production system in order to minimize or eliminate waste while maximizing production flow. Today in a highly competitive local and global market, it is very much crucial to satisfy the changing demand of the customers. Thus, in today’s manufacturing industry there is an increased focus to produce the right product at right time. The prime objective of this paper to apply a significant lean manufacturing tool know as Value Stream Mapping (VSM. To fulfil this objective a fundamental principles of lean were implemented and VSM was generated to analyse the production flow at an automotive industry and improve the current operating condition to overcome the difficulties with current state of work through time study, Takt time calculation, modifying work cell layout. And based on the future state of VSM, final results showed that by implementing this lean techniques, Production Lead-time (PLT decreased from 7.6 days to 3.2 days, and the cycle time is decrease up to 73%.

TEA controllable preparation of magnetite nanoparticles (Fe3O4 NPs) with excellent magnetic properties

Science.gov (United States)

Han, Chengliang; Zhu, Dejie; Wu, Hanzhao; Li, Yao; Cheng, Lu; Hu, Kunhong

2016-06-01

A fast and controllable synthesis method for superparamagnetic magnetite nanoparticles (Fe3O4 NPs) was developed in Fe(III)-triethanolamine (TEA) solution. The phase structure, morphology and particle size of the as-synthesized samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the magnetic particles were pure Fe3O4 with mean sizes of approximately 10 nm. The used TEA has key effects on the formation of well dispersing Fe3O4 NPs. Vibrating sample magnetometer (VSM) result indicated that the as-obtained Fe3O4 NPs exhibited superparamagnetic behavior and the saturation magnetization (Ms) was about 70 emu/g, which had potential applications in magnetic science and technology.

Influence of different synthesis conditions on properties of oleic acid-coated-Fe3O4 nanoparticles

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Aliakbari Atieh

2015-03-01

Full Text Available In the present paper, iron oxide nanoparticles coated by oleic acid have been synthesized in different conditions by coprecipitation method. For investigating the effect of time spent on adding the oleic acid to the precursor solution, two different processes have been considered. The as synthesized samples were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM and Fourier transform infrared spectroscopy (FT-IR. Magnetic measurement was carried out at room temperature using a vibrating sample magnetometer (VSM. The results show that the magnetic nanoparticles decorated with oleic acid decreased the saturation of magnetization. From the data, it can also be concluded that the magnetization of Fe3O4/oleic acid nanoparticles depends on synthesis conditions.

Electromagnetic properties of photodefinable barium ferrite polymer composites

Science.gov (United States)

Sholiyi, Olusegun; Lee, Jaejin; Williams, John D.

2014-07-01

This article reports the magnetic and microwave properties of a Barium ferrite powder suspended in a polymer matrix. The sizes for Barium hexaferrite powder are 3-6 μm for coarse and 0.8-1.0 μm for the fine powder. Ratios 1:1 and 3:1 (by mass) of ferrite to SU8 samples were characterized and analyzed for predicting the necessary combinations of these powders with SU8 2000 Negative photoresist. The magnetization properties of these materials were equally determined and were analyzed using Vibrating Sample Magnetometer (VSM). The Thru, Reflect, Line (TRL) calibration technique was employed in determining complex relative permittivity and permeability of the powders and composites with SU8 between 26.5 and 40 GHz.

Electromagnetic properties of photodefinable barium ferrite polymer composites

Directory of Open Access Journals (Sweden)

Olusegun Sholiyi

2014-07-01

Full Text Available This article reports the magnetic and microwave properties of a Barium ferrite powder suspended in a polymer matrix. The sizes for Barium hexaferrite powder are 3–6 μm for coarse and 0.8–1.0 μm for the fine powder. Ratios 1:1 and 3:1 (by mass of ferrite to SU8 samples were characterized and analyzed for predicting the necessary combinations of these powders with SU8 2000 Negative photoresist. The magnetization properties of these materials were equally determined and were analyzed using Vibrating Sample Magnetometer (VSM. The Thru, Reflect, Line (TRL calibration technique was employed in determining complex relative permittivity and permeability of the powders and composites with SU8 between 26.5 and 40 GHz.

Multiferroic properties of BiFeO3/BaTiO3 multilayered thin films

International Nuclear Information System (INIS)

Sharma, Savita; Tomar, Monika; Kumar, Ashok; Puri, Nitin K.; Gupta, Vinay

2014-01-01

Multilayered structures of multiferroic BiFeO 3 (BFO) and ferroelectric BaTiO 3 (BTO) have been fabricated using pulsed laser deposition (PLD). Ferromagnetic and ferroelectric properties of the multilayered system (BFO/BTO) have been investigated. It could be inferred that the magnetization increases with the incorporation of BTO buffer layer, which indicates a coupling between the ferroelectric and ferromagnetic orders. Vibrating sample magnetometer (VSM) measurements performed on the prepared multiferroic samples show that the magnetization is significantly increased (M s =56.88 emu/cm 3 ) for the multilayer system with more number of layers (four) keeping the total thickness of the multilayered system constant (350 nm) meanwhile maintaining the sufficiently enhanced ferroelectric properties (P r =29.68 µC/cm 2 )

Suggested search for 207Pb nuclear Schiff moment in PbTiO3 ferroelectric

International Nuclear Information System (INIS)

Mukhamedjanov, T.N.; Sushkov, O.P.

2005-01-01

We suggest two types of experiments, NMR and macroscopic magnetometry, with solid PbTiO 3 to search for the nuclear Schiff moment of 207 Pb. Both kinds of experiments promise substantial improvement over the presently achieved sensitivities. Statistical considerations show that the improvement of the current sensitivity can be up to ten orders of magnitude for the magnetometry experiment and up to seven orders of magnitude for the NMR experiment. Such significant enhancement is due to the strong internal electric field of the ferroelectric, as well as due to the possibility to cool the nuclear-spin subsystem in the compound down to nanokelvin temperatures

Preparation of yttrium iron garnet (YIG) by modified domestic iron oxide

International Nuclear Information System (INIS)

Mozaffari, M.; Amighian

2002-01-01

Iron oxide by product of a local steel complex was modified to use for preparation of Yttrium iron garnet (YIG). The improvement was necessary to reduce impurities, especially the Si0 2 and Cl contents, which have deteriorative effects on magnetic properties and equipment used for preparation of the samples. The modified iron oxide was then mixed with Yttrium oxide of Merck Company in appropriate proportion to obtain a stoichiometric single phase YIG, using the conventional ceramic technique. XRD and SEM equipments were used to identify the resulting phases and microstructure respectively. Magnetic parameters were measured by VSM. Curie temperature of the samples was obtained by DTG (M) method. The results were compared with those obtained from samples that made by Merck iron oxide. There are small differences between the results. This was discussed according to extra pores and minute secondary phase in the samples made by domestic iron oxide. (Author)

Magnetic properties of soft layer/FePt-MgO exchange coupled composite Perpendicular recording media

Institute of Scientific and Technical Information of China (English)

Yin Jin-Hua; Takao Suzuki; Pan Li-Qing

2008-01-01

The magnetic properties of exchange coupled composite(ECC)media that are composed of perpendicular magnetic recording media FePt-MgO and two kinds of soft layers have been studied by using an x-ray diffractometer,a polar Kerr magneto-optical system(PMOKE)and a vibrating sample magnetometer(VSM).The results show that ECC media can reduce the coercivities of perpendicular magnetic recording media FePt-MgO.The ECC media with granular-type soft layers have weaker exchange couplings between magnetic grains and the magnetization process,for ECC media of this kind mainly follow the Stoner-Wohlfarth model.

Synthesis of magnetite octahedrons from iron powders through a mild hydrothermal method

International Nuclear Information System (INIS)

Mao Baodong; Kang Zhenhui; Wang Enbo; Lian Suoyuan; Gao Lei; Tian Chungui; Wang Chunlei

2006-01-01

Magnetite (Fe 3 O 4 ) octahedral particles were fabricated from iron powders through a simple one-step alkali-assisted hydrothermal process. The crystallinity, morphology, and structural features of the as-prepared magnetite particles were investigated using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The values of saturation magnetization (M s ) and coercivity (H) of the magnetite octahedrons characterized on a vibrating sample magnetometer (VSM) are 89.81 emu/g and 70.6 Oe, respectively. The concentration of NaOH and the reaction temperature played a key role in the formation of the magnetite octahedrons

Synthesis and characterization of MnO2 nanowires

Science.gov (United States)

Ghorbani, Mohammad Hossein; Davarpanah, Abdol Mahmood

2017-01-01

Manganese oxides are of more interest to researchers because of their ability as catalysts and lithium batteries. In this research, MnO2 nanowires with diameter about 45 nm were synthesized by sol-gel method at room temperature (RT). Effect of increasing the annealing temperature from 400∘C to 600∘C on crystalline structure of nanostructure were studied and average crystallite size was estimated about 22 nm. X-ray Diffraction (XRD) method, Energy-Dispersive X-ray Diffraction (EDXD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) were used to characterize the nanowires of MnO2.

Manganese ferrite prepared using reverse micelle process: Structural and magnetic properties characterization

Energy Technology Data Exchange (ETDEWEB)

Hashim, Mohd, E-mail: md.hashim09@gmail.com [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Shirsath, Sagar E. [Spin Device Technology Centre, Department of Engineering, Shinshu University, Nagano 380-8553 (Japan); Meena, S.S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mane, M.L. [Department of Physics, S.G.R.G. Shinde Mahavidyalaya, Paranda 413502, MS (India); Kumar, Shalendra [School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); Bhatt, Pramod [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, Ravi [Centre for Material Science Engineering, National Institute of Technology, Hamirpur, HP (India); Prasad, N.K.; Alla, S.K. [Deptartment of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Shah, Jyoti; Kotnala, R.K. [National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Mohammed, K.A. [Department of Mathematics & Physics Sciences, College of Arts and Sciences, University of Nizwa, Nizwa (Oman); Şentürk, Erdoğan [Department of Physics, Sakarya University, Esentepe, 54187 Sakarya (Turkey); Alimuddin [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India)

2015-09-05

Highlights: • Preparation of Mn{sup 3+} substituted MnFe{sub 2}O{sub 4} ferrite by Reverse microemulsion process. • Characterization by XRD, SEM, VSM, Mössbauer spectroscopy and dielectric measurements techniques. • Magnetic properties of MnFe{sub 2}O{sub 4} enhanced after Mn{sup 3+} substitution. • The dielectric constant and ac conductivity increased with Mn{sup 3+} substitution. - Abstract: Reverse microemulsion process was employed to prepare of nanocrystalline Mn{sup 3+} substituted MnFe{sub 2−x}Mn{sub x}O{sub 4} ferrites. The structural, magnetic and dielectric properties were studied for different concentrations of Mn{sup 3+}. The structural and microstructural properties were analyzed using X-ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy techniques. The phase identification of the materials was studied by Rietveld refined XRD patterns which reveals single phase with cubic symmetry for the samples. The lattice parameters were ranged in between 8.369 and 8.379 Å and do not show any significant change with the substitution of Mn{sup 3+}. The average particles size was found to be around 11 ± 3 nm. Magnetization results obtained from the vibrating sample magnetometer (VSM) confirm that the substitution of Mn{sup 3+} in MnFe{sub 2}O{sub 4} ferrite caused an increase in the saturation magnetization and coercivity. The dependence of Mössbauer parameters on Mn{sup 3+} substitution has been analyzed. Magnetic behavior of the samples were also studied at field cooled (FC) and zero field cooled (ZFC) mode. The dependence of Mössbauer parameters on Mn{sup 3+} substitution was also analyzed. All the magnetic characterization shows that Mn{sup 3+} substitution enhance the magnetic behavior of MnFe{sub 2}O{sub 4} ferrite nanoparticles.

Elimination of copper and nickel from wastewater by electrooxidation method

Energy Technology Data Exchange (ETDEWEB)

Kazeminezhad, Iraj, E-mail: I.Kazeminezhad@scu.ac.ir [Physics Department, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Mosivand, Saba [Physics Department, Faculty of Science, Lorestan University, Khorram-Abad, Lorestan (Iran, Islamic Republic of)

2017-01-15

Electrooxidation method was used to remove copper and nickel from water by iron sacrificial sheets in an electrolytic cell. The effect of various voltages, electrooxidation time, and the initial pH of water has been studied on removal efficiency. The concentration of heavy metals before and after treatment was determined by an AAS instrument. The sludge obtained after treatment has been characterized using XRD, FESEM, and VSM. Our results show that the operational parameters play an important role on removal process. AAS results confirmed that the concentration of heavy metal pollutants in the water effectively decreases by increasing the applied voltage, electrochemical reaction time, or the initial pH of water. Based on these results it is possible to highly decrease the concentration of Ni or Cu from water at pH ∼4.5 by applying ∼28 V for 60 min. The FESEM images showed the nano-size of synthesized particles during water treatment. The element maps confirmed the presence of iron, oxygen, and heavy metal pollutants in precipitate after water treatment. The XRD patterns of powder sample obtained after removal of Ni or Cu show the reflections of Fe{sub 3}O{sub 4} and some small peaks which are correspond to different compound of metal pollutants. VSM results showed that the sludge samples are magnetically soft and their specific magnetization depends on removal conditions. The magnetic property of the sludge samples helps to separate them easily from water using magnetic field. - Highlights: • Electrooxidation method was used to remove copper and nickel from water. • By applying a potential between two electrodes the nanosorbents are generated in situ. • The operational parameters play an important role on removal process. • The concentration of metal in water decreases by increasing voltage, time, or pH of water. • The magnetic property of the sludge helps the magnetic separation.

Hydrothermal synthesis and characterizations of Ti substituted Mn-ferrites

Energy Technology Data Exchange (ETDEWEB)

Mostafa, Nasser Y., E-mail: nmost69@yahoo.com [Faculty of Science, Taif University, P.O. Box 888 Al-Haweiah, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt); Hessien, M.M. [Faculty of Science, Taif University, P.O. Box 888 Al-Haweiah, Taif (Saudi Arabia); Advanced materials Division-Central metallurgical R and D Institute (CMRDI), P.O. Box 87 Helwan, Cairo (Egypt); Shaltout, Abdallah A. [Faculty of Science, Taif University, P.O. Box 888 Al-Haweiah, Taif (Saudi Arabia); Spectroscopy Department, Physics Division, National Research Center, El Behooth Str., 12622 Dokki, Cairo (Egypt)

2012-07-15

Highlights: Black-Right-Pointing-Pointer Hydrothermal synthesized of well-crystallized Ti-substituted MnFe{sub 2}O{sub 4} nanoparticles at 180 Degree-Sign C without any calcination step. The chemical composition was represented by Mn{sub 1-2x}Ti{sub x}Fe{sub 2}O{sub 4} with x having values 0.0, 0.1, 0.2, 0.3 and 0.4. Black-Right-Pointing-Pointer The change in lattice parameter and saturation magnetization with increasing Ti-substitution was investigated and explained. Black-Right-Pointing-Pointer The change in microstructure due to Ti{sup 4+} ions substitutions was investigated using TEM analysis. - Abstarct: A series of well-crystallized Mn{sub 1-2x}Ti{sub x}Fe{sub 2}O{sub 4} nanoparticles with x values of 0.0, 0.1, 0.2, 0.3 and 0.4 have been synthesized by hydrothermal route at 180 Degree-Sign C in the presence of NaOH as mineralizer. The obtained ferrite samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The XRD analysis showed that pure single phases of cubic ferrites were obtained with x up to 0.2. However, samples with x > 0.2 showed traces of unreacted anatase. The increase in Ti-substitution up to x = 0.2 leads to an increase in the lattice parameter of the prepared ferrites. On the other hand, the increase in Ti-substitution over x = 0.2 leads to a decrease in the lattice parameter. The average crystallite size was in the range of 39-57 nm, where it is increased by increasing the Ti-substitution up to x = 0.3, then decreased for x = 0.4. According to VSM results, the saturation magnetization increased with Ti ion substitution of x = 0.1 and decreased for x > 0.1.

Delayed villous maturation of the placenta: quantitative assessment in different cohorts.

LENUS (Irish Health Repository)

Treacy, Ann

2013-01-01

Placental villous maturation is maximal in the 3rd trimester, with an abundance of terminal villi. Delayed villous maturation (DVM) of the placenta is associated with chromosomal abnormalities, gestational diabetes, and an adverse outcome. This study compares quantitative assessment of vasculo-syncytial membranes (VSM) in cases of liveborn infants, perinatal deaths, and controls. Cases were selected as follows: (1) liveborn infants with a qualitative diagnosis of DVM (n  =  15); (2) controls matched for gestational age whose placentas did not have DVM (n  =  15); (3) stillbirths (SB)\\/neonatal deaths (NND) showing DVM (n  =  13); and (4) SB from autopsies in which DVM was felt to be the cause of death (COD) (n  =  12). Vasculo-syncytial membranes were counted in 10 terminal villi in each of 10 consecutive high-power fields on 3 slides. Data analysis was carried out using SPSS. Liveborn cases with DVM showed statistically significantly less VSM than controls (mean 1.01 vs 2.42, P < 0.0001). The SB\\/NND group also showed significantly less VSM than the control group (mean 0.46 vs 2.42, P < 0.0001) and less than the liveborn DVM group (mean 0.46 vs 1.01, P  =  0.001). The COD group was significantly different from the control group (mean 0.42 vs 2.42, P < 0.0001) and the liveborn DVM group (mean 0.42 vs 1.01, P < 0.0001) but not significantly different from the SB\\/NND group. There is a quantitative reduction in VSM in cases of DVM compared to controls.

St. Francis' Nursing Home, Mount Oliver, Dundalk, Louth.

LENUS (Irish Health Repository)

Treacy, Ann

2013-01-01

Placental villous maturation is maximal in the 3rd trimester, with an abundance of terminal villi. Delayed villous maturation (DVM) of the placenta is associated with chromosomal abnormalities, gestational diabetes, and an adverse outcome. This study compares quantitative assessment of vasculo-syncytial membranes (VSM) in cases of liveborn infants, perinatal deaths, and controls. Cases were selected as follows: (1) liveborn infants with a qualitative diagnosis of DVM (n  =  15); (2) controls matched for gestational age whose placentas did not have DVM (n  =  15); (3) stillbirths (SB)\\/neonatal deaths (NND) showing DVM (n  =  13); and (4) SB from autopsies in which DVM was felt to be the cause of death (COD) (n  =  12). Vasculo-syncytial membranes were counted in 10 terminal villi in each of 10 consecutive high-power fields on 3 slides. Data analysis was carried out using SPSS. Liveborn cases with DVM showed statistically significantly less VSM than controls (mean 1.01 vs 2.42, P < 0.0001). The SB\\/NND group also showed significantly less VSM than the control group (mean 0.46 vs 2.42, P < 0.0001) and less than the liveborn DVM group (mean 0.46 vs 1.01, P  =  0.001). The COD group was significantly different from the control group (mean 0.42 vs 2.42, P < 0.0001) and the liveborn DVM group (mean 0.42 vs 1.01, P < 0.0001) but not significantly different from the SB\\/NND group. There is a quantitative reduction in VSM in cases of DVM compared to controls.

Structural, electrical and magnetic properties of Sc{sup 3+} doped Mn-Zn ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Angadi, V. Jagdeesha [Department of Physics, Bangalore University, Bangalore 560056 (India); Choudhury, Leema [Department of Physics, K.G. Reddy College of Engineering & Technology, Moinabad, 501504 Ranga Reddy, Telangana (India); Sadhana, K. [Department of Physics, University College of Science, Osmania University, Saifabad, Hyderabad 500004 (India); Liu, Hsiang-Lin [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China); Sandhya, R. [Department of Physics, University College of Science, Osmania University, Hyderabad 500007 (India); Matteppanavar, Shidaling; Rudraswamy, B.; Pattar, Vinayak; Anavekar, R.V. [Department of Physics, Bangalore University, Bangalore 560056 (India); Praveena, K., E-mail: praveenaou@gmail.com [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China)

2017-02-15

Sc{sup 3+} doped Mn{sub 0.5}Zn{sub 0.5}Sc{sub y}Fe{sub 2−y}O{sub 4} (y=0.00, 0.01, 0.03 and 0.05) nanoparticles were synthesized by solution combustion method using mixture of fuels were reported for the first time. The mixture of fuels plays an important role in obtaining nano crystalline, single phase present without any heat treatment. X-ray diffraction (XRD) results confirm the formation of the single-phase ferrites which crystallize in cubic spinel structure. The Fourier transform infrared spectra (FTIR) exhibit two prominent bands around 360 cm{sup −1} and 540 cm{sup −1} which are characteristic feature of spinel ferrite. The transmission electron microscope (TEM) micrographs revealed the nanoparticles to be nearly spherical in shape and of fairly uniform size. The room temperature impedance spectra (IS) and vibrating sample magnetometry (VSM) measurements were carried out in order to study the effect of doping (Sc{sup 3+}) on the characteristic properties of Mn-Zn ferrites. Further, the frequency dependent dielectric constant and dielectric loss were found to decrease with increasing multiple Sc{sup 3+} concentration. Nyquist plot in the complex impedance spectra suggest the existence of multiple electrical responses. Magnetic measurements reveals that saturation magnetization (M{sub s}), remnant magnetization (M{sub r}), magnetic moment (η{sub B}) and magnetic particle size (D{sub m}) increase with Sc{sup 3+} ion concentration up to x=0.03 and then decrease. The values of spin canting angle (α{sub Y-K}) and the magnetic particle size (D{sub m}) are found to be in the range of 68–75° and 10–19 nm respectively with Sc{sup 3+} concentration. The room temperature Mössbauer spectra were fitted with two sextets corresponding to ions at tetrahedral (A-) and octahedral (B-) sites confirms the spinel lattice. The ferromagnetic resonance (FMR) spectra's has shown that high concentration of scandium doping leads to an increase in dipolar interaction

Photo-, sono- and sonophotocatalytic degradation of methylene blue using Fe3O4/ZrO2 composites catalysts

Science.gov (United States)

Kristianto, Y.; Taufik, A.; Saleh, R.

2017-07-01

In the present work, magnetite material Fe3O4/ZrO2 with various molar ratios was prepared by the two-step method (sol-gel followed by the ultrasonic-assisted method). The as-prepared samples were fairly characterized by various characterization methods, such as X-ray Diffraction (XRD), Vibrating Sample Magnetometer (VSM), Fourier Transform Infrared (FT-IR) and Thermal Gravimetric Analysis (TGA). The catalytic performance of the as-prepared samples was evaluated based on the degradation of methylene blue under UV light, ultrasound and combination of UV and ultrasound irradiation. The results revealed that the sample with Fe3O4:ZrO2 molar ratio of 0.5:1 showed the best catalytic performance under UV, ultrasound and UV + ultrasound irradiation. The degradation of methylene blue follows the order: sonophotocatalytic > sonocatalytic > photocatalytic. In addition, the effect of various scavengers has also been studied. Furthermore, all prepared samples could be used as a convenient recyclable catalyst.

Effects of Gd substitution on the structural and magnetic properties of strontium hexaferrites

Energy Technology Data Exchange (ETDEWEB)

Litsardakis, G. [Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)]. E-mail: Lits@eng.auth.gr; Manolakis, I. [Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Serletis, C. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Efthimiadis, K.G. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)

2007-09-15

The effect of Gd substitution in M-type strontium hexaferrites has been examined in two series of samples, (Sr{sub 1-x}Gd{sub x})O.5.25Fe{sub 2}O{sub 3} and Sr{sub 1-x}Gd{sub x}Fe{sub 12-x}Co{sub x}O{sub 19}, both prepared by the ceramic method, where x=0-0.40. The samples have been characterized by XRD, VSM and SEM-EDAX techniques. All substituted samples present primarily the hexaferrite structure. Sample (Sr{sub 0.95}Gd{sub x0.05})O.5.25Fe{sub 2}O{sub 3} is single phase. Formation of impurity phases is affected by stoichiometry and presence of Co. In Sr-Gd samples, coercivity showed a maximum value of 305kA/m (3.8kOe) for x=0.20, while remanence and saturation magnetization did not decrease. Coercivity and magnetization in the Sr-Gd-Co series decreased steadily with substitution degree.

Influence of Zn/Fe Molar Ratio on Optical and Magnetic Properties of ZnO and ZnFe2O4 Nanocrystal as Calcined Products of Layered Double Hydroxides

Directory of Open Access Journals (Sweden)

Abdullah Ahmed Ali Ahmed

2014-01-01

Full Text Available The coprecipitation method has been used to synthesize layered double hydroxide (Zn-Fe-LDH nanostructure at different Zn2+/Fe3+ molar ratios. The structural properties of samples were studied using powder X-ray diffraction (PXRD. LDH samples were calcined at 600°C to produce mixed oxides (ZnO and ZnFe2O4. The crystallite size of mixed oxide was found in the nanometer scale (18.1 nm for ZnFe2O4 and 43.3 nm for ZnO. The photocatalytic activity of the calcination products was investigated using ultraviolet-visible-near infrared (UV-VIS-NIR diffuse reflectance spectroscopy. The magnetic properties of calcined LDHs were investigated using a vibrating sample magnetometer (VSM. The calcined samples showed a paramagnetic behavior for all Zn2+/Fe3+ molar ratios. The effect of molar ratio on magnetic susceptibility of the calcined samples was also studied.

Influence of Nd3+ substitution on structural and magnetic properties of Zinc ferrite

International Nuclear Information System (INIS)

Sharma, Nidhi; Kumar, Sushil; Aghamkar, Praveen

2013-01-01

Zinc ferrite samples, ZnFe 2-x Nd x O 4 (where x= 0.05, 0.075, 0.1), have been synthesized by coprecipitation technique and then heat treated at different temperatures. The structural and magnetic studies have been conducted by X-ray diffraction, Fourier transform infrared spectroscopy, Transmission electron microscopy and Vibrating sample magnetometer. X-ray diffraction shows the polycrystalline nature and spinel structure of samples. The average particle sizes of 28-32 nm are obtained through TEM images, which are in good agreement with the XRD results. The lattice constant has been found to increase with increase in Nd 3+ content in the sample. FTIR transmission spectra show two strong absorption bands in the frequency range 400-600 cm -1 , which are respectively attributed to the tetrahedral and octahedral sites of spinel structure. Magnetic properties such as coercivity, retentivity, as demonstrated in hysteresis curve of samples recorded by VSM, display super paramagnetic behaviour at 800℃. (author)

Structural and magnetic properties of FeCoC system obtained by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Rincón Soler, A. I. [Universidad Tecnológica de Pereira, Fac. de Ciencias, Depto. de Física (Colombia); Rodríguez Jacobo, R. R., E-mail: rrrodriguez@uao.edu.co [Universidad Autónoma de Occidente, Fac. de Ciencias Básicas, Depto. de Física (Colombia); Medina Barreto, M. H.; Cruz-Muñoz, B. [Universidad Tecnológica de Pereira, Fac. de Ciencias, Depto. de Física (Colombia)

2017-11-15

Fe{sub 96−X}Co{sub X}C{sub 4} (x = 0, 10, 20, 30, 40 at. %) alloys were obtained by mechanical alloying of Fe, C and Co powders using high-energy milling. The structural and magnetic properties of the alloy system were analyzed by X-ray diffraction, Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mössbauer Spectrometry at room temperature. The X-ray diffraction patterns showed a BCC-FeCoC structure phase for all samples, as well as a lattice parameter that slightly decreases with Co content. The saturation magnetization and coercive field were analyzed as a function of Co content. The Mössbauer spectra were fitted with a hyperfine magnetic field distribution showing the ferromagnetic behavior and the disordered character of the samples. The mean hyperfine magnetic field remained nearly constant (358 T) with Co content.

Structural and magnetic properties of FeCoC system obtained by mechanical alloying

International Nuclear Information System (INIS)

Rincón Soler, A. I.; Rodríguez Jacobo, R. R.; Medina Barreto, M. H.; Cruz-Muñoz, B.

2017-01-01

Fe 96−X Co X C 4 (x = 0, 10, 20, 30, 40 at. %) alloys were obtained by mechanical alloying of Fe, C and Co powders using high-energy milling. The structural and magnetic properties of the alloy system were analyzed by X-ray diffraction, Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mössbauer Spectrometry at room temperature. The X-ray diffraction patterns showed a BCC-FeCoC structure phase for all samples, as well as a lattice parameter that slightly decreases with Co content. The saturation magnetization and coercive field were analyzed as a function of Co content. The Mössbauer spectra were fitted with a hyperfine magnetic field distribution showing the ferromagnetic behavior and the disordered character of the samples. The mean hyperfine magnetic field remained nearly constant (358 T) with Co content.

Magnetism and structural chemistry of the n=2 Ruddlesden-Popper phase La3LiMnO7

International Nuclear Information System (INIS)

Battle, Peter D.; Burley, Jonathan C.; Gallon, Daniel J.; Grey, Clare P.; Sloan, Jeremy

2004-01-01

Polycrystalline samples of the n=2 Ruddlesden-Popper phase La 3 LiMnO 7 have been prepared and characterized. X-ray and neutron diffraction suggest that the structure is tetragonal with a disordered distribution of Li and Mn cations over the octahedral sites, but 6 Li MAS NMR shows that the Li and Mn are 1:1 ordered locally. Electron microscopy shows that the stacking of the cation-ordered, perovskite-like bilayers along the crystallographic z-axis is disordered on the distance scale sampled by X-ray and neutron diffraction. Magnetometry data and neutron diffraction data collected at 2 K together suggest that the Mn cations within each structural domain order antiferromagnetically at 14 K, but that the disorder along z prevents the establishment of long-range magnetic order

Superconductivity in LaCu{sub 6} and possible applications

Energy Technology Data Exchange (ETDEWEB)

Herrmannsdoerfer, Thomas; Pobell, Frank; Sebek, Josef; Svoboda, Pavel

2003-05-15

We have measured the ac susceptibility and resistivity of highly pure samples of the intermetallic compound LaCu{sub 6} down to ultralow temperatures. We have prepared the samples by arc melting of stoichiometric amounts of 99.99% La and 99.9999% Cu in a water-cooled copper crucible under Ar protective atmosphere and analysed them by X-ray diffraction and SQUID magnetometry. At T{<=}T{sub c}=0.16 K we observe a superconducting transition. Due to the manifold physical properties of isostructural ReCu{sub 6} compounds (e.g. RE = Ce: heavy fermion system, RE=Pr: hyperfine enhanced nuclear spin system, RE = Nd: electronic antiferromagnet), numerous studies of interplay phenomena may become possible in the quasibinary compounds RE{sub 1-x}La{sub x}Cu{sub 6}, respectively.

Electromagnetic characterization of strontium ferrite powders in series 2000, SU8 polymer

Science.gov (United States)

Sholiyi, Olusegun; Williams, John

2014-12-01

In this article, electromagnetic characterization of strontium hexaferrite powders and composites with SU8 was carried out to determine their compatibility with micro and millimeter wave fabrications. The structures of both powders and their composites were scanned with electron microscope to produce the SEM images. Two powder sizes (0.8-1.0 μm and 3-6 μm), were mixed with SU8, spin cast and patterned on wafer, and then characterized using energy dispersive x-ray spectrometry, ferromagnetic resonance (FMR) and vibrating sample magnetometry. In this investigation, FMRs of the samples were determined at 60 GHz while their complex permittivity and permeability were determined using rectangular waveguide method of characterization between 26.5 and 40 GHz frequency range. The results obtained show no adverse effects on the electromagnetic properties of the composites except some slight shift in the resonant frequencies due to anisotropic field of the samples.

Growth of room temperature ferromagnetic Ge1-xMnx quantum dots on hydrogen passivated Si (100) surfaces

Science.gov (United States)

Gastaldo, Daniele; Conta, Gianluca; Coïsson, Marco; Amato, Giampiero; Tiberto, Paola; Allia, Paolo

2018-05-01

A method for the synthesis of room-temperature ferromagnetic dilute semiconductor Ge1-xMnx (5 % < x < 8 %) quantum dots by molecular beam epitaxy by selective growth on hydrogen terminated silicon (100) surface is presented. The functionalized substrates, as well as the nanostructures, were characterized in situ by reflection high-energy electron diffraction. The quantum dots density and equivalent radius were extracted from field emission scanning electron microscope pictures, obtained ex-situ. Magnetic characterizations were performed by superconducting quantum interference device vibrating sample magnetometry revealing that ferromagnetic order is maintained up to room temperature: two different ferromagnetic phases were identified by the analysis of the field cooled - zero field cooled measurements.

Development of a magnetic system for the treatment of Helicobacter pylori infections

International Nuclear Information System (INIS)

Silva, Erica L.; Carvalho, Juliana F.; Pontes, Thales R.F.; Oliveira, Elquio E.; Francelino, Barbara L.; Medeiros, Aldo C.; Egito, E. Socrates T. do; Araujo, Jose H.; Carrico, Artur S.

2009-01-01

We report a study to develop a magnetic system for local delivery of amoxicillin. Magnetite microparticles produced by coprecipitation were coated with a solution of amoxicillin and Eudragit S100 by spray drying. Scanning electron microscopy, optical microscopy, X-ray powder diffraction and vibrating sample magnetometry revealed that the particles were superparamagnetic, with an average diameter of 17.2 μm, and an initial susceptibility controllable by the magnetite content in the suspension feeding the sprayer. Our results suggest a possible way to treat Helicobacter pylori infections, using an oral drug delivery system, and open prospects to coat magnetic microparticles by spray drying for biomedical applications.

Development of a magnetic system for the treatment of Helicobacter pylori infections

Energy Technology Data Exchange (ETDEWEB)

Silva, Erica L.; Carvalho, Juliana F.; Pontes, Thales R.F.; Oliveira, Elquio E. [Departamento de Farmacia, Universidade Federal do Rio Grande do Norte, Rua Gal Gustavo Cordeiro de Farias s.n, Petropolis, 59010-180 Natal-RN (Brazil); Francelino, Barbara L.; Medeiros, Aldo C. [Departamento de Medicina, Universidade Federal do Rio Grande do Norte, Rua Gal Gustavo Cordeiro de Farias s.n, Petropolis, 59010-180 Natal-RN (Brazil); Egito, E. Socrates T. do [Departamento de Farmacia, Universidade Federal do Rio Grande do Norte, Rua Gal Gustavo Cordeiro de Farias s.n, Petropolis, 59010-180 Natal-RN (Brazil); Araujo, Jose H. [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Campus Universitario, 59078-970 Natal-RN (Brazil); Carrico, Artur S. [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Campus Universitario, 59078-970 Natal-RN (Brazil)], E-mail: ascarrico@dfte.ufrn.br

2009-05-15

We report a study to develop a magnetic system for local delivery of amoxicillin. Magnetite microparticles produced by coprecipitation were coated with a solution of amoxicillin and Eudragit S100 by spray drying. Scanning electron microscopy, optical microscopy, X-ray powder diffraction and vibrating sample magnetometry revealed that the particles were superparamagnetic, with an average diameter of 17.2 {mu}m, and an initial susceptibility controllable by the magnetite content in the suspension feeding the sprayer. Our results suggest a possible way to treat Helicobacter pylori infections, using an oral drug delivery system, and open prospects to coat magnetic microparticles by spray drying for biomedical applications.

On the role of Fe ions on magnetic properties of doped TiO2 nanoparticles

Science.gov (United States)

Tolea, F.; Grecu, M. N.; Kuncser, V.; Constantinescu, S. Gr.; Ghica, D.

2015-04-01

The role of iron doping on magnetic properties of hydrothermal anatase TiO2:57Fe (0-1 at. %) nanoparticles is investigated by combining superconducting quantum interference device magnetometry with Mössbauer and electron paramagnetic resonance techniques. The results on both as-prepared and thermally treated samples in reduced air atmosphere reveal complexity of magnetic interactions, in connection to certain iron ion electron configurations and defects (oxygen vacancies, F-center, and Ti3+ ions). The distribution of iron ions is predominantly at nanoparticle surface layers. Formation of weak ferromagnetic domains up to 380 K is mainly related to defects, supporting the bound magnetic polaron model.

On the role of Fe ions on magnetic properties of doped TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Tolea, F.; Grecu, M. N., E-mail: mgrecu@infim.ro; Kuncser, V.; Constantinescu, S. Gr.; Ghica, D. [National Institute of Materials Physics (NIMP), Mǎgurele-Ilfov 077125 (Romania)

2015-04-06

The role of iron doping on magnetic properties of hydrothermal anatase TiO{sub 2}:{sup 57}Fe (0–1 at. %) nanoparticles is investigated by combining superconducting quantum interference device magnetometry with Mössbauer and electron paramagnetic resonance techniques. The results on both as-prepared and thermally treated samples in reduced air atmosphere reveal complexity of magnetic interactions, in connection to certain iron ion electron configurations and defects (oxygen vacancies, F-center, and Ti{sup 3+} ions). The distribution of iron ions is predominantly at nanoparticle surface layers. Formation of weak ferromagnetic domains up to 380 K is mainly related to defects, supporting the bound magnetic polaron model.

Magneto-optical and transport studies of ZnO-based dilute magnetic semiconductors

Energy Technology Data Exchange (ETDEWEB)

Behan, A.J. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Neal, J.R. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom)]. E-mail: J.R.Neal@Sheffield.ac.uk; Ibrahim, R.M. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Mokhtari, A. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Ziese, M. [Universitaet Leipzig, Fakultaet fuer Physik und Geowissenschaften, Abteilung Supra leitung und Magnetismus, Linnestrasse 5, 04103 Leipzig (Germany); Blythe, H.J. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Fox, A.M. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Gehring, G.A. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom)

2007-03-15

Thin film samples of ZnO doped with V were grown on sapphire substrates by pulsed laser deposition (PLD). The magnetization was measured by SQUID magnetometry and the films were found to be ferromagnetic at room temperature. The transmission, Faraday rotation and magnetic circular dichroism were measured as a function of frequency at room temperature over an energy range of 1.5-4.0 eV and carrier concentrations were determined from Hall effect measurements. Clear magneto-optical signals that are ferromagnetic in origin were observed at the ZnO band edge and the optimal conditions for observing large ferromagnetic magneto-optic signals are discussed.

Evolution of the magnetic properties of Co10Cu90 nanoparticles prepared by wet chemistry with thermal annealing.

Science.gov (United States)

García, I; Echeberria, J; Kakazei, G N; Golub, V O; Saliuk, O Y; Ilyn, M; Guslienko, K Y; González, J M

2012-09-01

Nanoparticles of Co10Cu90 alloy have been prepared by sonochemical wet method. According to transmission electron microscopy, bimetallic particles with typical diameter of 50-100 nm consisting of nanocrystallites with average diameter of 15-20 nm were obtained. The samples were annealed at 300 degrees C and 450 degrees C. Zero field cooled and field cooled temperature dependences of magnetization in the temperature range of 5-400 K at 50 Oe, as well as magnetization hysteresis loops at 15, 100 and 305 K were measured by vibrating sample magnetometry. Presence of antiferromagnetic phase, most probably of the oxide Co3O4, was observed in as-prepared sample. The lowest coercivity was found for the CoCu sample annealed at-300 degrees C, whereas for as prepared sample and the one annealed at 450 degrees C it was significantly higher. The samples were additionally probed by continuous wave ferromagnetic resonance at room, temperature using a standard X-band electron spin resonance spectrometer. A good correspondence between evolution of the coercivity and the microwave resonance fields with annealing temperature was observed.

Towards a 3-D magnetometry by neutron reflectometry

Energy Technology Data Exchange (ETDEWEB)

Fermon, C. [CEA/Saclay, Dept. de Recherche sur l' Etat Condense, les Atomes et les Molecules (DRECAM), 91 - Gif-sur-Yvette (France); Gilles, B. [Ecole Nationale Superieure d' Electrochimie et d' Electrometallurgie, 38 - Grenoble (France). Lab. de Thermodynamique et Physico-Chimie Metallurgiques; Marty, A. [CEA Grenoble, Dept. de Recherche Fondamentale sur la Matiere Condensee (DRFMC), 38 (France); Ott, F.; Menelle, A. [Laboratoire Leon Brillouin (LLB) - CEA/Saclay, 91 - Gif-sur-Yvette (France)

1998-07-01

Polarised Neutron reflectometry with spin analysis allows one to probe the in-depth magnetic profiles of thin films down to about 100 nm. Analysis of specular reflections gives access to the in-plane vectorial absolute magnetic moment. Off-specular reflectometry gives information about lateral contrasts with typical lengths ranging from 5 {mu}m to 100 {mu}m. Furthermore, surface diffraction at grazing angle gives access to transverse dimensions between 10 nm and 300 nm with a resolution in that direction of several nm. The combination of these 3 techniques applied to thin magnetic objects like thin films, arrays of lines or arrays of dots, leads to 3-D patterns in the reciprocal space. The method is extremely sensitive while giving the average on a rather large surface. Such a technique is therefore not applicable for the study of a single magnetic dot, but it generates unique results in several cases including patterns of domain walls in thin films with perpendicular anisotropy, arrays of magnetic dots, patterned fines in magnetic thin films. (authors)

Advanced MOKE magnetometry in wide-field Kerr-microscopy

Science.gov (United States)

Soldatov, I. V.; Schäfer, R.

2017-10-01

The measurement of MOKE (Magneto-Optical Kerr Effect) magnetization loops in a wide-field Kerr microscope offers the advantage that the relevant domain images along the loop can be readily recorded. As the microscope's objective lens is exposed to the magnetic field, the loops are usually strongly distorted by non-linear Faraday rotations of the polarized light that occur in the objective lens and that are superimposed to the MOKE signal. In this paper, an experimental method, based on a motorized analyzer, is introduced which allows to compensate the Faraday contributions, thus leading to pure MOKE loops. A wide field Kerr microscope, equipped with this technology, works well as a laser-based MOKE magnetometer, additionally offering domain images and thus providing the basis for loop interpretation.

SQUID magnetometry from nanometer to centimeter length scales

International Nuclear Information System (INIS)

Hatridge, Michael J.

2010-01-01

The development of Superconducting QUantum Interference Device (SQUID)-based magnetometer for two applications, in vivo prepolarized, ultra-low field MRI of humans and dispersive readout of SQUIDs for micro- and nano-scale magnetometery, are the focus of this thesis.

UAV magnetometry in mineral exploration and infrastructure detection

Science.gov (United States)

Braun, A.; Parvar, K.; Burns, M.

2015-12-01

Magnetic surveys are critical tools in mineral exploration and UAVs have the potential to carry magnetometers. UAV surveys can offer higher spatial resolution than traditional airborne surveys, and higher coverage than terrestrial surveys. However, the main advantage is their ability to sense the magnetic field in 3-D, while most airborne or terrestrial surveys are restricted to 2-D acquisition. This study compares UAV magnetic data from two different UAVs (JIB drone, DJI Phantom 2) and three different magnetometers (GEM GSPM35, Honeywell HMR2300, GEM GST-19). The first UAV survey was conducted using a JIB UAV with a GSPM35 flying at 10-15 m above ground. The survey's goal was to detect intrusive Rhyolite bodies for primary mineral exploration. The survey resulted in a better understanding of the validity/resolution of UAV data and led to improved knowledge about the geological structures in the area. The results further drove the design of a following terrestrial survey. Comparing the UAV data with an available airborne survey (upward continued to 250 m) reveals that the UAV data has superior spatial resolution, but exhibits a higher noise level. The magnetic anomalies related to the Rhyolite intrusions is about 109 nT and translates into an estimated depth of approximately 110 meters. The second survey was conducted using an in-house developed UAV magnetometer system equipped with a DJI Phantom 2 and a Honeywell HMR2300 fluxgate magnetometer. By flying the sensor in different altitudes, the vertical and horizontal gradients can be derived leading to full 3-D magnetic data volumes which can provide improved constraints for source depth/geometry characterization. We demonstrate that a buried steam pipeline was detectable with the UAV magnetometer system and compare the resulting data with a terrestrial survey using a GEM GST-19 Proton Precession Magnetometer.

Low-power attitude determination for magnetometry planetary missions

DEFF Research Database (Denmark)

Christensen, Thorbjørn Helvig

This work covers the subject of orientation or attitude in space and on the surface of a planet. Different attitude sensor technologies have been investigated with emphasis on very low power consumption and mass. In addition robust methods for attitude determination have been covered again...... with emphasis on the limited budget onboard very small satellites. A true low-power attitude sensor using the Anisotropic Magneto Resistor effect have been designed to late prototype state. Two prototypes of the AMR magnetometer have been built. One of the prototypes has an analog output and the second...... calibration has been performed on both of the prototypes of the AMR magnetometer with very good overall result. Different attitude representations such as orthogonal matrices, Euler angles and quaternions are presented. Also methods for attitude determination of a sensor platform with more than one vector...

SQUID magnetometry from nanometer to centimeter length scales

Energy Technology Data Exchange (ETDEWEB)

Hatridge, Michael J. [Univ. of California, Berkeley, CA (United States)

2010-06-01

The development of Superconducting QUantum Interference Device (SQUID)-based magnetometer for two applications, in vivo prepolarized, ultra-low field MRI of humans and dispersive readout of SQUIDs for micro- and nano-scale magnetometery, are the focus of this thesis.

Enhancement of room temperature ferromagnetic behavior of rf sputtered Ni-CeO_2 thin films

International Nuclear Information System (INIS)

Murugan, R.; Vijayaprasath, G.; Mahalingam, T.; Ravi, G.

2016-01-01

Highlights: • Ni-CeO_2 thin films deposited by using rf Magnetron sputtering with different concentrations of Ni. • Deposited thin films have single crystalline and uniform surface morphology. • Photoluminescence and micro-Raman spectra were interpreted for Ni-CeO_2 thin films. • XPS spectra confirmed Ni ions were present in the doped CeO_2 thin films. • Ni ions induced ferromagnetic behavior of Ni-CeO_2 films were confirmed through VSM. - Abstract: Ni-doped CeO_2 thin films were prepared under Ar"+ atmosphere on glass substrates using rf magnetron sputtering. To assess the properties of the prepared thin films, the influence of various amounts of Ni dopant on structural, morphological, optical, vibrational, compositional and magnetic properties of the CeO_2 films were studied by using X-Ray diffraction (XRD), atomic force microscope (AFM), photoluminescence (PL), micro-Raman, X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). XRD patterns for all the samples revealed the expected CeO_2 cubic fluorite-type structure and Ni ions were uniformly distributed in the samples. AFM images of the prepared samples indicate high dense, columnar structure with uniform distribution of CeO_2. Room-temperature photoluminescence (PL) and micro-Raman spectroscopic studies revealed an increase of oxygen vacancies with higher concentration of Ni in CeO_2. XPS results confirm the presence of Ni_2_p, O_1_s and Ce and depict that cerium is present as both Ce"4"+ and Ce"3"+ oxidation states in Ce_1_−_xNi_xO_2 (x = 15%) thin film. Field dependent magnetization measurements revealed a paramagnetic behavior for pure CeO_2, while a ferromagnetic behavior appeared when Ni is doped in CeO_2 films. Doping dependent magnetization measurements suggest that the observed ferromagnetism is due to the presence of metallic Ni clusters with nanometric size and broad size distribution.

Structural and magnetic properties of Nd–Mn substituted Y-type hexaferrites synthesized by microemulsion method

Energy Technology Data Exchange (ETDEWEB)

Murtaza, G., E-mail: gm_rai786@yahoo.com [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Ahmad, R.; Hussain, T.; Ayub, R. [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Ali, Irshad [Department of Physics, Bahauddin Zakariya University, Multan (Pakistan); Khan, Muhammad Azhar [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan)

2014-07-25

Highlights: • Synthesis via a chemical route microemulsion method. • Samples were characterized with XRD, SEM, AFM, FTIR, Dielectric Measurements and VSM. • Single phase patterns were recorded. • A marked decrease in coercivity has been observed with the substitution of Nd–Mn. • These ferrites are suitable for multi-layer chip components in hyper-frequency. - Abstract: Nd–Mn substituted hexaferrites of composition Sr{sub 2−x}Nd{sub x}Ni{sub 0.5}Co{sub 1.5}Fe{sub 12−y}Mn{sub y}O{sub 22} (x = 0.0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30, y = 0.0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75) were synthesized using microemulsion method. The synthesized materials are characterized using different techniques including X-ray diffraction (XRD), scanning electron microscopy(SEM), atomic force microscopy (AFM), Fourier transform Infrared spectroscopy (FTIR), Inductance capacitance resistance (LCR) meter and Vibrating sample magnetic magnetometer (VSM). For all samples, a single Y-type phase was established and the lattice constants have been calculated. XRD patterns reveal the significant increase in line broadening which indicates a decrease of grain size. The samples exhibit well defined crystallization; all of them are hexagonal platelet grains. With the increasing substitution level of Nd–Mn, the average grain diameter decreases. The dielectric constant ε{sup ′} and dielectric loss factor ε″ are found to decrease initially with an increase in frequency and reached a constant value at higher frequency, exhibiting a frequency-independent behavior at higher frequencies. The dielectric loss tangent tanδ was found to decrease with an increase in the frequency. The H{sub c} decreases remarkably with increasing Nd and Mn ions content. It was found that the particle size could be effectively decreased and coercivity H{sub c} could easily be controlled by varying the concentration (x) without significantly decreasing saturation magnetization.

Facile synthesis of multifunctional attapulgite/Fe{sub 3}O{sub 4}/polyaniline nanocomposites for magnetic dispersive solid phase extraction of benzoylurea insecticides in environmental water samples

Energy Technology Data Exchange (ETDEWEB)

Yang, Xiaoling; Qiao, Kexin; Ye, Yiren; Yang, Miyi; Li, Jing; Gao, Haixiang; Zhang, Sanbing; Zhou, Wenfeng; Lu, Runhua, E-mail: rhlu@cau.edu.cn

2016-08-31

In this study, the superparamagnetic attapulgite/Fe{sub 3}O{sub 4}/polyaniline (ATP/Fe{sub 3}O{sub 4}/PANI) nanocomposites were successfully synthesized by a one-pot method. Fe (III) was applied as both the oxidant for the oxidative polymerization of aniline and the single iron source of Fe{sub 3}O{sub 4} formed by the redox reaction between aniline and Fe (III). The ATP/Fe{sub 3}O{sub 4}/PANI was used as sorbent for magnetic dispersive solid phase extraction (MDSPE) of benzoylurea insecticides (BUs) in environmental water samples. The as-prepared nanocomposite sorbents were characterized by Fourier transform infrared spectra (FT-IR), X Ray diffraction (XRD), scanning electron microscopy(SEM), transmission electron microscopy (TEM), and vibrating sample magnetometry. Various experimental parameters affecting the ATP/Fe{sub 3}O{sub 4}/PANI-based MDSPE procedure, including the composition of the nanocomposite sorbents, amount of ATP/Fe{sub 3}O{sub 4}/PANI nanocomposites, vortex time, pH, and desorption conditions were investigated. Under the optimal conditions, a good linearity was observed for all target analytes, with correlation coefficients (r{sup 2}) ranging from 0.9985 to 0.9997; the limits of detection (LOD) were in the range of 0.02–0.43 μg L{sup −1}, and the recoveries of analytes using the proposed method ranged between 77.37% and 103.69%. The sorbents exhibited an excellent reproducibility in the range of 1.52–5.27% in extracting the five target analytes. In addition, the intra-day and inter-day precision values were found to be in the range of 0.78–6.86% and 1.66–8.41%, respectively. Finally, the proposed ATP/Fe{sub 3}O{sub 4}/PANI-based MDSPE method was successfully applied to analyze river water samples by rapid preconcentration of BUs. - Highlights: • A novel superparamagnetic ATP/Fe{sub 3}O{sub 4}/PANI nanocomposite was first introduced in MDSPE. • ATP/Fe{sub 3}O{sub 4}/PANI nanocomposites exhibited fast adsorption and desorption

Using Seismic Interferometry to Investigate Seismic Swarms

Science.gov (United States)

Matzel, E.; Morency, C.; Templeton, D. C.

2017-12-01

Seismicity provides a direct means of measuring the physical characteristics of active tectonic features such as fault zones. Hundreds of small earthquakes often occur along a fault during a seismic swarm. This seismicity helps define the tectonically active region. When processed using novel geophysical techniques, we can isolate the energy sensitive to the fault, itself. Here we focus on two methods of seismic interferometry, ambient noise correlation (ANC) and the virtual seismometer method (VSM). ANC is based on the observation that the Earth's background noise includes coherent energy, which can be recovered by observing over long time periods and allowing the incoherent energy to cancel out. The cross correlation of ambient noise between a pair of stations results in a waveform that is identical to the seismogram that would result if an impulsive source located at one of the stations was recorded at the other, the Green function (GF). The calculation of the GF is often stable after a few weeks of continuous data correlation, any perturbations to the GF after that point are directly related to changes in the subsurface and can be used for 4D monitoring.VSM is a style of seismic interferometry that provides fast, precise, high frequency estimates of the Green's function (GF) between earthquakes. VSM illuminates the subsurface precisely where the pressures are changing and has the potential to image the evolution of seismicity over time, including changes in the style of faulting. With hundreds of earthquakes, we can calculate thousands of waveforms. At the same time, VSM collapses the computational domain, often by 2-3 orders of magnitude. This allows us to do high frequency 3D modeling in the fault region. Using data from a swarm of earthquakes near the Salton Sea, we demonstrate the power of these techniques, illustrating our ability to scale from the far field, where sources are well separated, to the near field where their locations fall within each other

Impaired spatial body representation in complex regional pain syndrome type 1 (CRPS I).

Science.gov (United States)

Reinersmann, Annika; Landwehrt, Julia; Krumova, Elena K; Ocklenburg, Sebastian; Güntürkün, Onur; Maier, Christoph

2012-11-01

Recently, a shift of the visual subjective body midline (vSM), a correlate of the egocentric reference frame, towards the affected side was reported in patients with complex regional pain syndrome (CRPS). However, the specificity of this finding is as yet unclear. This study compares 24 CRPS patients to 21 patients with upper limb pain of other origin (pain control) and to 24 healthy subjects using a comprehensive test battery, including assessment of the vSM in light and dark, line bisection, hand laterality recognition, neglect-like severity symptoms, and motor impairment (disability of the arm, shoulder, and hand). 1-way analysis of variance, t-tests, significance level: 0.05. In the dark, CRPS patients displayed a significantly larger leftward spatial bias when estimating their vSM, compared to pain controls and healthy subjects, and also reported lower motor function than pain controls. For right-affected CRPS patients only, the deviation of the vSM correlated significantly with the severity of distorted body perception. Results confirm previous findings of impaired visuospatial perception in CRPS patients, which might be the result of the involvement of supraspinal mechanisms in this pain syndrome. These mechanisms might accentuate the leftward bias that results from a right-hemispheric dominance in visuospatial processing and is known as pseudoneglect. Pseudoneglect reveals itself in the tendency to perceive the midpoint of horizontal lines or the subjective body midline left of the centre. It was observable in all 3 groups, but most pronounced in CRPS patients, which might be due to the cortical reorganisation processes associated with this syndrome. Copyright © 2012 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Influence of doping of Mn{sup +2} and Co{sup +2} in ZnO synthesized by combustion reaction for use in DMS; Influencia da dopagem do Mn{sup +2} e Co{sup +2} no ZnO sintetizado por reacao de combustao para uso em SMD

Energy Technology Data Exchange (ETDEWEB)

Torquato, R.; Costa, A.C.F.M. [Universidade Federal de Campina Grande (UFCG), Campina Grande, PB (Brazil). Departamento de Engenharia de Materiais; Shirsath, S.E. [Department of Physics, Vivekanand College, Aurangabad, MS (India); Kiminami, R.H.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

2011-07-01

ZnO is a semiconducting ceramics used for development of electrical devices such as varistors, chemical sensors, piezoelectric transducers and diluted magnetic semiconductors. So this paper proposes to investigate the influence of doping of 0.1 mol of Mn{sup +2} and Co{sup +2} on the structure, morphology and magnetic measurements of ZnO synthesized by combustion reaction in DMS applications. The resulting samples were characterized by XRD, SEM, BET, VSM. The combustion temperature for samples doped with Mn and Co were 512 deg C and 397 °C, respectively. XRD results for both samples showed the formation of ZnO as the major phase, with crystallite size of 21nm and 23nm and a surface area of 59 and 17 m2/g for samples doped with Mn{sup +2} and Co{sup +2}, respectively. The magnetic measurements showed values of saturation magnetization and coercive force of 12 and 3 emu/g, and 94 and 237Oe, respectively. (author)

A study on magneto-optic properties of CoxMg1-xFe2O4 nanoferrofluids

Science.gov (United States)

Karthick, R.; Ramachandran, K.; Srinivasan, R.

2018-04-01

Nanoparticles of CoxMg1-xFe2O4 (x = 0.1, 0.5, 0.9) were synthesized using chemical co-precipitation method. Characterization by X-ray diffraction technique confirmed the formation of cubic crystalline structure and the crystallite size of the samples obtained using Debye-Scherrer approximation were found to increase with increasing cobalt substitution. Surface morphology and the Chemical composition of the samples were visualized using scanning electron microscope (SEM) with energy dispersive analysis of X-rays (EDAX). Room temperature magnetic parameters of the nanoparticles by vibrating sample magnetometer (VSM) revealed the magnetic properties such as Saturation magnetization (Ms), Remanent magnetization (Mr) and Coercive field (Hc) found to increase with increasing cobalt substitution. Faraday rotation measurements on CoxMg1-xFe2O4 ferrofluids exhibited increase in rotation with cobalt substitution. Further, there is an increase in Faraday rotation with increasing magnetic field for all the samples.

Loss of long-range magnetic order in a nanoparticle assembly due to random anisotropy

International Nuclear Information System (INIS)

Binns, C; Howes, P B; Baker, S H; Marchetto, H; Potenza, A; Steadman, P; Dhesi, S S; Roy, M; Everard, M J; Rushforth, A

2008-01-01

We have used soft x-ray photoemission electron microscopy (XPEEM) combined with x-ray magnetic circular dichroism (XMCD) and DC SQUID (superconducting quantum interference device) magnetometry to probe the magnetic ground state in Fe thin films produced by depositing size-selected gas-phase Fe nanoparticles with a diameter of 1.7 nm (∼200 atoms) onto Si substrates. The depositions were carried out in ultrahigh vacuum conditions and thicknesses of the deposited film in the range 5-50 nm were studied. The magnetometry data are consistent with the film forming a correlated super-spin glass with a magnetic correlation length ∼5 nm. The XPEEM magnetic maps from the cluster-assembled films were compared to those for a conventional thin Fe film with a thickness of 20 nm produced by a molecular beam epitaxy (MBE) source. Whereas a normal magnetic domain structure is observed in the conventional MBE thin film, no domain structure could be observed in any of the nanoparticle films down to the resolution limit of the XMCD based XPEEM (100 nm) confirming the ground state indicated by the magnetometry measurements. This observation is consistent with the theoretical prediction that an arbitrarily weak random anisotropy field will destroy long-range magnetic order

Effects of Modified Iron Oxide Nanoparticles on the Thermal and Dynamic Mechanical Properties of Cellulose Poly(vinyl alcohol Blend Films

Directory of Open Access Journals (Sweden)

Mehdi Roohani

2015-11-01

Full Text Available This study was designed to investigate the effect of modified iron oxide nanoparticles (MINP and cellulose nanocrystals (NCC on magnetic, thermal and dynamic-mechanical properties of poly(vinyl alcohol based nanocomposites. Fe3O4 nanoparticles have been synthesized using a chemical co-precipitation route. Nanocomposite films were developed by solvent casting method and their properties were characterized by vibrating sample magnetometer (VSM, differential scanning calorimetry (DSC and dynamic mechanical analysis (DMA. DSC results found that with incorporation of nanoparticles, the glass transition temperature increase slightly to higher temperatures; however, the degree of crystallinity and the values of the melting temperature are found to decrease. Dynamic mechanical analysis revealed that, at the elevated temperatures, improvement of mechanical properties due to the presence of nanoparticles was even more noticeable. Addition of nanoparticles resulted in increased thermal stability of PVA due to the reduction in mobility of matrix molecules by strong hydrogen bonds between nanocomposite components. Results indicated that, MINP and NCC have synergistic effect on improving of poly(vinyl alcohol properties. The VSM findings showed that the saturation magnetization of iron oxide nanoparticles reduced after modification. This can be attributed to formation of hydroxyapatite on nanoparticles surface. The saturation magnetization (Ms of PVA- MINP films was higher than PVA-MINP- NCC film. This result probably is related to more amount of magnetic nanoparticles in PVA-MINP films.

Substrates effect on Zn1-xMnxO thin films grown by RF magnetron sputtering

International Nuclear Information System (INIS)

Elanchezhiyan, J.; Bhuvana, K.P.; Gopalakrishnan, N.; Balasubramanian, T.

2008-01-01

In this paper, we have presented the surface effect of the substrates on Mn doped ZnO (Zn 1-x Mn x O) thin films grown on Si(1 0 0) and sapphire [i.e. Al 2 O 3 (0 0 0 1)] by RF magnetron sputtering. These grown films have been characterized by X-ray diffraction (XRD), photoluminescence (PL) and vibrating sample magnetometer (VSM) to know its structural, optical and magnetic properties. All these properties have been found to be strongly influenced by the substrate surface on which the films have been deposited. The XRD results show that the Mn doped ZnO films deposited on Si(1 0 0) exhibit a polycrystalline nature whereas the films on sapphire substrate have only (0 0 2) preferential orientations indicating that the films are single crystalline. The studies of room temperature PL spectra reveal that the Zn 1-x Mn x O/Si(1 0 0) system is under severe compressive strain while the strain is almost relaxed in Zn 1-x Mn x O/Al 2 O 3 (0 0 0 1) system. It has been observed from VSM studies that Zn 1-x Mn x O/Al 2 O 3 (0 0 0 1) system shows ferromagnetic nature while the paramagnetic behaviour observed in Zn 1-x Mn x O/Si(1 0 0) system

Activation of room temperature ferromagnetism in ZnO films by surface functionalization with thiol and amine

International Nuclear Information System (INIS)

Jayalakshmi, G.; Gopalakrishnan, N.; Balasubramanian, T.

2013-01-01

Highlights: ► Room temperature ferromagnetism (RTFM) is observed in surface functionalized ZnO films. ► Surface functionalization is a new approach to make ZnO as ferromagnetic. ► The RTFM is attributed to the interaction between the adsorbates and the surface of ZnO. ► The oxygen vacancies are passivated upon surface functionalization. - Abstract: In this paper, we report the activation of room temperature ferromagnetism in ZnO films by surface functionalization with thiol and amine. The pure and surface functionalized ZnO films have been examined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and vibrating sample magnetometer (VSM) measurements. XRD measurements show that all the films have single phase and (0 0 2) preferred orientation. The chemical bonding of ZnO with thiol and amine molecules has been confirmed by XPS measurements. The quenching of visible emission in PL spectra indicates that the surface defects are passivated by functionalization with thiol and amine. Surface functionalization of ZnO films with thiol and amine induces robust room temperature ferromagnetism in ZnO films as evidenced from VSM measurements. It is concluded that the observed ferromagnetic behavior in functionalized ZnO films is attributed to the different electronegativity of the atom in the thiol (or amine) and the surface of ZnO.

A superparamagnetic Fe{sub 3}O{sub 4}-graphene oxide nanocomposite for enrichment of nuciferine in the extract of Nelumbinis Folium (Lotus leaf)

Energy Technology Data Exchange (ETDEWEB)

Fan, Jie-Ping, E-mail: jasperfan@163.com [Key Laboratory of Poyang Lake Ecology and Bio-Resource Utilization of Ministry of Education, Department of Chemical Engineering, Nanchang University, Nanchang 330031 (China); Zheng, Bing; Qin, Yu; Yang, Dan; Liao, Dan-Dan; Xu, Xiao-Kang [Key Laboratory of Poyang Lake Ecology and Bio-Resource Utilization of Ministry of Education, Department of Chemical Engineering, Nanchang University, Nanchang 330031 (China); Zhang, Xue-Hong [School of Foreign Language, Nanchang University, Nanchang 330031 (China); Zhu, Jian-Hang [Key Laboratory of Poyang Lake Ecology and Bio-Resource Utilization of Ministry of Education, Department of Chemical Engineering, Nanchang University, Nanchang 330031 (China)

2016-02-28

Graphical abstract: - Highlights: • A superparamagnetic Fe3O4-graphene oxide (MGO) nanocomposite was prepared. • It is characterized by TEM, XPS, VSM, XRD and Raman spectroscopy. • The adsorption kinetics, isotherms and reusability of MGO were also investigated. • MGO was applied to enrich nuciferine in the extract of Nelumbinis Folium. - Abstract: In this work, a superparamagnetic Fe{sub 3}O{sub 4}-graphene oxide (MGO) nanocomposite was prepared by one-step chemical co-precipitation method, and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), powder X-ray diffraction (PXRD), Raman spectroscopy and nitrogen adsorption–desorption curve. The as-prepared MGO was used to adsorb nuciferine, and the adsorption kinetic, isotherm and reusability of MGO were also investigated. The results showed that the adsorption of nuciferine on MGO reached its equilibrium very quickly (within 10 min) due to the two-dimensional carbon nanostructure of GO. In comparison with MGO, five conventional sorbents, i.e., macroporous resin D-101, silica gel, reverse phase silica gel (RP-C18) and cation exchange resin and polyamide, were also used to evaluate their adsorption capabilities. Therefore, MGO combined the advantages of both superparamagnetic particle and GO, i.e., easy separation and high absorption capacity. Finally, MGO was successfully applied to enrichment and separation of nuciferine in the extract of Nelumbinis Folium (Lotus leaf).

Using test of Colour Semantic Differential for research into organizational culture

Directory of Open Access Journals (Sweden)

Martina Rešlová

2013-01-01

Full Text Available The aim of this article is to show the possibility of using a combination of the Values Survey Module 1994 (VSM 94 and the Test of Colour Semantic Differential (TCSD for research into organizational culture. The results of the VSM 94 enable the researcher to determine which poles of Hofstede’s cultural dimensions a particular working group is in fact approaching while the data obtained through TCSD make it possible to define how employees consciously rate and unconsciously perceive expressions related to Hofstede’s cultural dimensions, or how they identify themselves with the researched values, respectively. The final values from the VSM 94 are compared with Hofstede’s national values and it is investigated whether it is possible to speak about the impact of national culture on corporate culture. This article also describes advantages and disadvantages of TCSD as well as the possibilities of its more focused use for research into organizational culture. TCSD has not been widely used for research into organizational culture although it has many practical uses thanks to the ability to work with respondents’ unconsciousness in connection with culture.

Multiferroic properties of BiFeO{sub 3}/BaTiO{sub 3} multilayered thin films

Energy Technology Data Exchange (ETDEWEB)

Sharma, Savita [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Department of Applied Physics, Delhi Technological University, Delhi 110042 (India); Tomar, Monika [Physics Department, Miranda House, University of Delhi, Delhi 110007 (India); Kumar, Ashok [CSIR—National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Puri, Nitin K. [Department of Applied Physics, Delhi Technological University, Delhi 110042 (India); Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

2014-09-01

Multilayered structures of multiferroic BiFeO{sub 3} (BFO) and ferroelectric BaTiO{sub 3} (BTO) have been fabricated using pulsed laser deposition (PLD). Ferromagnetic and ferroelectric properties of the multilayered system (BFO/BTO) have been investigated. It could be inferred that the magnetization increases with the incorporation of BTO buffer layer, which indicates a coupling between the ferroelectric and ferromagnetic orders. Vibrating sample magnetometer (VSM) measurements performed on the prepared multiferroic samples show that the magnetization is significantly increased (M{sub s}=56.88 emu/cm{sup 3}) for the multilayer system with more number of layers (four) keeping the total thickness of the multilayered system constant (350 nm) meanwhile maintaining the sufficiently enhanced ferroelectric properties (P{sub r}=29.68 µC/cm{sup 2})

Magnetic and electrical properties of the La doped Mn-Zn ferrite nanoparticles synthesized by the co-precipitation method

International Nuclear Information System (INIS)

Chandel, Vipin; Vijeta; Thakur, Atul; Thakur, Preeti

2013-01-01

In the present study, nano crystalline Mn-Zn-La ferrite with chemical formula Mn 0.4 Zn 0.6 La 0.3 Fe 1.7 O 4 was successfully synthesized by a co-precipitation method. The prepared powders were presintered at 700℃. The pallets formed were finally sintered at 700℃, 800℃ and 900℃ for 3h reach. The structural and morphological behavior was investigated by the X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD confirms the formation of the expected spinel structure. Scanning Electron Microscopy (SEM) was used to characterize the microstructure of the ferrite samples i.e. grain morphology, grain size, grain size distribution and shape. Fourier transform infrared spectroscopy (FTIR) confirms the peaks of different molecules in the given sample. Electrical and magnetic properties were studied by using dc resistivity set up and vibrating sample magnetometer (VSM). (author)

Fast Extraction and Detection of 4-Methylimidazole in Soy Sauce Using Magnetic Molecularly Imprinted Polymer by HPLC.

Science.gov (United States)

Feng, Zufei; Lu, Yan; Zhao, Yingjuan; Ye, Helin

2017-11-02

On the basis of magnetic molecularly imprinted polymer (MMIP) solid-phase extraction coupled with high performance liquid chromatography, we established a new method for the determination of the 4-methylimidazole (4-MEI) in soy sauce. Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) were used to characterize the synthesized MMIPs. To evaluate the polymers, batch rebinding experiments were carried out. The binding strength and capacity were determined from the derived Freundlich isotherm (FI) equation. The selective recognition capability of MMIPs was investigated with a reference compound and a structurally similar compound. As a selective pre-concentration sorbents for 4-methylimidazole in soy sauce, the MMIPs showed a satisfied recoveries rate of spiked samples, ranged from 97% to 105%. As a result, the prepared MMIPs could be applied to selectively pre-concentrate and determine 4-methylimidazole in soy sauce samples.

On the magnetic behavior of polycrystalline RBaCo205+δ synthesized by solid state and wet chemical routes

International Nuclear Information System (INIS)

Gómez, L; Galeano, V; Paucar, C; Morán, O; Vallejo, E; Gómez, A

2014-01-01

In this paper, polycrystalline RBaCo 2 O 5+δ (R = La, Y, Eu) samples were obtained through solid state reaction and polymeric precursor method. The crystalline quality of the samples was carefully evaluated by means of X-ray diffraction. Depending on the R cation, the main phases were characterized in a tetragonal P4/mmm, orthorhombic Pmmm or trigonal R-3c structure. The oxygen content, being a fundamental parameter in the studied system, was determined by iodometric tritration. While no stoichiometric oxygen content was determined, the value of 5 ended up being close to 0.5 for all the samples studied. VSM magnetization measurements were taken according to the zero field cooling protocol. The M(T) curves clearly shows the characteristic magnetic behavior of the cobaltate with stoichiometry 112. The temperature at which the paramagnetic-ferromagnetic-antiferromagnetic transition occurs varies with the cation R

Room temperature ferromagnetism in Fe-doped CeO2 nanoparticles.

Science.gov (United States)

Maensiri, Santi; Phokha, Sumalin; Laokul, Paveena; Seraphin, Supapan

2009-11-01

RT ferromagnetism was observed in nanoparticles of Fe-doped CeO2 (i.e., Ce(0.97)Fe(0.03)O2) synthesized by a sol-gel method. The undoped and Fe-doped CeO2 were characterized by XRD, Raman spectroscopy, TEM, and VSM. The undoped samples and Ce(0.97)Fe(0.03)O2 precursor exhibit a diamagnetic behavior. The 673 K-calcined Ce(0.97)Fe(0.03)O2 sample is paramagnetic whereas 773 and 873 K-calcined Ce(0.97)Fe(0.03)O2 samples are ferromagnetism having the magnetizations of 4.65 x 10(-3) emu/g and 6.20 x 10(-3) emu/g at 10 kOe, respectively. Our results indicate that the ferromagnetic property is intrinsic to the Fe-doped CeO2 system and is not a result of any secondary magnetic phase or cluster formation.

The fabrication and the coercivity mechanism of segmented (Ni/Fe)m composite nanowire arrays

International Nuclear Information System (INIS)

Xue, D S; Shi, H G; Si, M S

2004-01-01

Arrays of segmented (Ni/Fe) m (m = 1,2,3,4,5) composite nanowires about 3 μm in length and with aspect ratios of about 60 were electrodeposited on anodic porous alumina templates using a dual bath. The structure, morphology and magnetic properties of the samples were characterized by means of x-ray diffraction, transmission electron microscopy and vibrating sample magnetometry, respectively. It is found that Fe(110) and Ni(111) orientations along nanowire axis are preferred. The large aspect ratio of the composite nanowires reveals a strong shape magnetic anisotropy. As the number of the Ni/Fe composite segments m increases, the coercivity of the nanowire arrays, with the magnetic field applied parallel to the wire, gradually increases. The coercivity variation of the segmented composite nanowires is closely related to the effective exchange coupling between the Ni and Fe segments

Facile synthesis of polymer-enveloped ultrasmall superparamagnetic iron oxide for magnetic resonance imaging

International Nuclear Information System (INIS)

Hong Jun; Xu Dongmei; Yu Jiahui; Gong Peijun; Ma Hongjuan; Yao Side

2007-01-01

Ultrasmall superparamagnetic iron oxide (USPIO) with synthetic polymer, based on magnetite core, was synthesized via facile photochemical in situ polymerization. A possible mechanism of photochemical in situ polymerization was proposed. The obtained polymer-enveloped UPSIO was characterized by transmission electron microscopy (TEM), photo-correlation spectroscopy (PCS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis and vibrating sampling magnetometer (VSM) measurement. Properties such as ultrasmall particle size, hydrophilicity, strong magnetization and surface characteristics, which are desirable for magnetic resonance imaging (MRI) contrast agents, were evaluated in detail. The resultant USPIO-based MRI contrast agent holds considerable promise in molecular MR tracking, MR immune imaging, cell tracking and targeted intracellular hyperthermia, etc

A Comparative Study on Magnetostructural Properties of Barium Hexaferrite Powders Prepared by Polyethylene Glycol

Directory of Open Access Journals (Sweden)

Zehra Durmus

2014-01-01

Full Text Available Nanocrystalline particles of barium hexaferrite were synthesized by a sol-gel combustion route using nitrate-citrate gels prepared from metal nitrates and citric acid solutions with Fe/Ba molar ratio 12. The present paper aims to study the effect of addition of polyethylene glycol (PEG solutions with different molecular weights (MW: 400, 2000, and 10.000 g/mol on magnetostructural properties of barium hexaferrite. The formation of the barium hexaferrite was inspected using X-ray diffraction (XRD analysis, Fourier transform infrared (FT-IR analysis, thermogravimetric (TGA analysis, scanning electron microscopy (SEM analysis and vibrating sample magnetometer (VSM analysis for magnetic measurements.

Electromagnetic characterization of strontium ferrite powders in series 2000, SU8 polymer

International Nuclear Information System (INIS)

Sholiyi, Olusegun; Williams, John

2014-01-01

In this article, electromagnetic characterization of strontium hexaferrite powders and composites with SU8 was carried out to determine their compatibility with micro and millimeter wave fabrications. The structures of both powders and their composites were scanned with electron microscope to produce the SEM images. Two powder sizes (0.8–1.0 μm and 3–6 μm), were mixed with SU8, spin cast and patterned on wafer, and then characterized using energy dispersive x-ray spectrometry, ferromagnetic resonance (FMR) and vibrating sample magnetometry. In this investigation, FMRs of the samples were determined at 60 GHz while their complex permittivity and permeability were determined using rectangular waveguide method of characterization between 26.5 and 40 GHz frequency range. The results obtained show no adverse effects on the electromagnetic properties of the composites except some slight shift in the resonant frequencies due to anisotropic field of the samples. (paper)

Copper nanoparticles functionalized PE: Preparation, characterization and magnetic properties

International Nuclear Information System (INIS)

Reznickova, A.; Orendac, M.; Kolska, Z.; Cizmar, E.; Dendisova, M.; Svorcik, V.

2016-01-01

Highlights: • Polyethylene (PE) surface was activated by argon plasma discharge. • Copper nanoparticles were coated on polyethylene via dithiol interlayer. • Prepared samples exhibit excellent structural and magnetic properties. • Studied properties may be utilized in design and fabrication of electronic devices. - Abstract: We report grafting of copper nanoparticles (CuNP) on plasma activated high density polyethylene (HDPE) via dithiol interlayer pointing out to the structural and magnetic properties of those composites. The as-synthesized Cu nanoparticles have been characterized by high-resolution transmission electron microscopy (HRTEM/TEM) and UV–vis spectroscopy. Properties of pristine PE and their plasma treated counterparts were studied by different experimental techniques: X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), zeta potential, electron spin resonance (ESR) and SQUID magnetometry. From TEM and HRTEM analyses, it is found that the size of high purity Cu nanoparticles is (12.2 ± 5.2) nm. It was determined that in the CuNPs, the copper atoms are arranged mostly in the (111) and (200) planes. Absorption in UV–vis region by these nanoparticles is ranging from 570 to 670 nm. EDS revealed that after 1 h of grafting are Cu nanoparticles homogeneously distributed over the whole surface and after 24 h of grafting Cu nanoparticles tend to aggregate slightly. The combined investigation of magnetic properties using ESR spectrometry and SQUID magnetometry confirmed the presence of copper nanoparticles anchored on PE substrate and indicated ferromagnetic interactions.