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1

Conjugation of manganese ferrite nanoparticles to an anti Sticholysin monoclonal antibody and conjugate applications  

Microsoft Academic Search

In this study the potential applications of manganese ferrite (MnFe2O4) nanoparticles for bioanalytical applications are evaluated. These magnetic nanoparticles show peroxidase-like activity similar to that reported for magnetite nanoparticles and peroxidase enzyme. Based on this finding, colloidal suspensions of manganese ferrite were conjugated to an anti-Sticholysin II (StII) monoclonal antibody. The resulting conjugate was then used as a revealing tool

V. Figueroa-Espí; A. Alvarez-Paneque; M. Torrens; A. J. Otero-González; E. Reguera

2011-01-01

2

Manganese ferrite-based nanoparticles induce ex vivo, but not in vivo, cardiovascular effects  

PubMed Central

Magnetic nanoparticles (MNPs) have been used for various biomedical applications. Importantly, manganese ferrite-based nanoparticles have useful magnetic resonance imaging characteristics and potential for hyperthermia treatment, but their effects in the cardiovascular system are poorly reported. Thus, the objectives of this study were to determine the cardiovascular effects of three different types of manganese ferrite-based magnetic nanoparticles: citrate-coated (CiMNPs); tripolyphosphate-coated (PhMNPs); and bare magnetic nanoparticles (BaMNPs). The samples were characterized by vibrating sample magnetometer, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. The direct effects of the MNPs on cardiac contractility were evaluated in isolated perfused rat hearts. The CiMNPs, but not PhMNPs and BaMNPs, induced a transient decrease in the left ventricular end-systolic pressure. The PhMNPs and BaMNPs, but not CiMNPs, induced an increase in left ventricular end-diastolic pressure, which resulted in a decrease in a left ventricular end developed pressure. Indeed, PhMNPs and BaMNPs also caused a decrease in the maximal rate of left ventricular pressure rise (+dP/dt) and maximal rate of left ventricular pressure decline (?dP/dt). The three MNPs studied induced an increase in the perfusion pressure of isolated hearts. BaMNPs, but not PhMNPs or CiMNPs, induced a slight vasorelaxant effect in the isolated aortic rings. None of the MNPs were able to change heart rate or arterial blood pressure in conscious rats. In summary, although the MNPs were able to induce effects ex vivo, no significant changes were observed in vivo. Thus, given the proper dosages, these MNPs should be considered for possible therapeutic applications.

Nunes, Allancer DC; Ramalho, Laylla S; Souza, Alvaro PS; Mendes, Elizabeth P; Colugnati, Diego B; Zufelato, Nicholas; Sousa, Marcelo H; Bakuzis, Andris F; Castro, Carlos H

2014-01-01

3

Galactosylated manganese ferrite nanoparticles for targeted MR imaging of asialoglycoprotein receptor  

NASA Astrophysics Data System (ADS)

Cancer cells can express specific biomarkers, such as cell membrane proteins and signaling factors. Thus, finding biomarkers and delivering diagnostic agents are important in the diagnosis of cancer. In this study, we investigated a biomarker imaging agent for the diagnosis of hepatic cancers. The asialoglycoprotein receptor (ASGPr) was selected as a biomarker for hepatoma cells and the ASGPr-targetable imaging agent bearing a galactosyl group was prepared using manganese ferrite nanoparticles (MFNP) and galactosylgluconic acid. The utility of the ASGPr-targetable imaging agent, galactosylated MFNP (G-MFNP) was assessed by several methods in ASGPr-expressing HepG2 cells as target cells and ASGPr-deficient MCF7 cells. Physical and chemical properties of G-MFNP were examined using Fourier-transform infrared spectroscopy, dynamic light scattering, zeta potential analysis, and transmission electron microscopy. No significant cytotoxicity was observed in either cell line. Targeting ability was assessed using flow cytometry, magnetic resonance imaging, inductively coupled plasma atomic emission spectroscopy, absorbance analysis, dark-field microscopy, Prussian blue staining, and transmission electron microscopy. We demonstrated that G-MFNP target successfully and bind to ASGPr-expressing HepG2 cells specifically. We suggest that these results will be useful in strategies for cancer diagnoses based on magnetic resonance imaging.

Yang, Seung-Hyun; Heo, Dan; Lee, Eugene; Kim, Eunjung; Lim, Eun-Kyung; Lee, Young Han; Haam, Seungjoo; Suh, Jin-Suck; Huh, Yong-Min; Yang, Jaemoon; Park, Sahng Wook

2013-11-01

4

Galactosylated manganese ferrite nanoparticles for targeted MR imaging of asialoglycoprotein receptor.  

PubMed

Cancer cells can express specific biomarkers, such as cell membrane proteins and signaling factors. Thus, finding biomarkers and delivering diagnostic agents are important in the diagnosis of cancer. In this study, we investigated a biomarker imaging agent for the diagnosis of hepatic cancers. The asialoglycoprotein receptor (ASGPr) was selected as a biomarker for hepatoma cells and the ASGPr-targetable imaging agent bearing a galactosyl group was prepared using manganese ferrite nanoparticles (MFNP) and galactosylgluconic acid. The utility of the ASGPr-targetable imaging agent, galactosylated MFNP (G-MFNP) was assessed by several methods in ASGPr-expressing HepG2 cells as target cells and ASGPr-deficient MCF7 cells. Physical and chemical properties of G-MFNP were examined using Fourier-transform infrared spectroscopy, dynamic light scattering, zeta potential analysis, and transmission electron microscopy. No significant cytotoxicity was observed in either cell line. Targeting ability was assessed using flow cytometry, magnetic resonance imaging, inductively coupled plasma atomic emission spectroscopy, absorbance analysis, dark-field microscopy, Prussian blue staining, and transmission electron microscopy. We demonstrated that G-MFNP target successfully and bind to ASGPr-expressing HepG2 cells specifically. We suggest that these results will be useful in strategies for cancer diagnoses based on magnetic resonance imaging. PMID:24192299

Yang, Seung-Hyun; Heo, Dan; Lee, Eugene; Kim, Eunjung; Lim, Eun-Kyung; Lee, Young Han; Haam, Seungjoo; Suh, Jin-Suck; Huh, Yong-Min; Yang, Jaemoon; Park, Sahng Wook

2013-11-29

5

Magnetocaloric effect in ferrite nanoparticles  

Microsoft Academic Search

A comparative study of the magnetocaloric effect (MCE) is reported in two different types of chemically synthesized magnetic nanoparticle systems—cobalt ferrite and manganese zinc ferrite with mean size around 5 and 15nm, respectively. While CoFe2O4 nanoparticles were synthesized using co-precipitation, the Mn0.68Zn0.25Fe2.07O4 (MZFO) nanoparticles were prepared by reverse micelle technique using AOT as surfactant. Our results indicate that the change

P. Poddar; J. Gass; D. J. Rebar; S. Srinath; H. Srikanth; S. A. Morrison; E. E. Carpenter

2006-01-01

6

Atomic engineering of mixed ferrite and core-shell nanoparticles.  

PubMed

Nanoparticulate ferrites such as manganese zinc ferrite and nickel zinc ferrite hold great promise for advanced applications in power electronics. The use of these materials in current applications requires fine control over the nanoparticle size as well as size distribution to maximize their packing density. While there are several techniques for the synthesis of ferrite nanoparticles, reverse micelle techniques provide the greatest flexibility and control over size, crystallinity, and magnetic properties. Recipes for the synthesis of manganese zinc ferrite, nickel zinc ferrite, and an enhanced ferrite are presented along with analysis of the crystalline and magnetic properties. Comparisons are made on the quality of nanoparticles produced using different surfactant systems. The importance of various reaction conditions is explored with a discussion on the corresponding effects on the magnetic properties, particle morphology, stoichiometry, crystallinity, and phase purity. PMID:16193949

Morrison, Shannon A; Cahill, Christopher L; Carpenter, Everett E; Calvin, Scott; Harris, Vincent G

2005-09-01

7

40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).  

Code of Federal Regulations, 2013 CFR

...treated manganese ferrite with acrylic ester polymer (generic). 721.10223 Section...treated manganese ferrite with acrylic ester polymer (generic). (a) Chemical substance...treated manganese ferrite with acrylic ester polymer (PMN P-09-582) is subject to...

2013-07-01

8

The role of fuel concentration on particle size and dielectric properties of manganese substituted zinc ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Mn substituted ZnFe2O4 nanoparticles were prepared by the auto-combustion method using different fuel ratios of 50%, 75% and 100%.The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectrum (EDX). Also, the dielectric behaviors of the samples were investigated for different annealing temperatures. The X-ray diffraction patterns indicated that the annealed samples resulted in the formation of crystalline powder and the presence of ?-Fe2O3 as a secondary phase. The average crystallite sizes of the samples are from ~12 to 60 nm. The external morphology and microstructure of the samples are tested by SEM and TEM. The effect of annealing temperature and particle size on dielectric properties such as dielectric constant (?) and dielectric loss (D) of the spinel MnxZn1-xFe2O4 nanoparticles was measured using impedance analyzer in the frequency range 100 kHz-5 MHz.

Ranjith Kumar, E.; Jayaprakash, R.

2014-10-01

9

Investigation of structural and magnetic properties of nanocrystalline manganese substituted lithium ferrites  

SciTech Connect

Nanocrystalline manganese substituted lithium ferrites Li{sub 0.5}Fe{sub 2.5-x}Mn{sub x}O{sub 4} (2.5<=x>=0) were prepared by sol-gel auto-combustion method. X-ray diffraction patterns revealed that as the concentration of manganese increased, the cubic phase changed to tetragonal. Magnetic properties were measured by hysteresis loop tracer technique. All the compositions indicated ferrimagnetic nature. The surface morphology of all the samples was studied by using scanning and transmission electron microscopy. The substitution of manganese ions in the lattice affected the structural as well as magnetic properties of spinels. - Graphical abstract: The synthesized nanoparticles shapes, sizes and size dispersibilities were obtained from the transmission electron microscopy (TEM). The TEM micrographs of synthesized samples revealed that, spherical shape with average particle size 50 nm. Selected area electron diffraction pattern (SAED) suggests the polycrystallinity and also the formation of spinel ferrites.

Hankare, P.P., E-mail: p_hankarep@rediffmail.co [Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra (India); Patil, R.P., E-mail: raj_rbm_raj@yahoo.co.i [Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra (India); Sankpal, U.B.; Jadhav, S.D. [Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra (India); Lokhande, P.D. [Pune University, Pune, Maharashtra, India. (India); Jadhav, K.M. [Dr. B.A.Marathwada University, Aurangabad 431004, Maharashtra (India); Sasikala, R. [Chemistry Division, Bhabha Atomic Research Center, Mumbai 400085, Maharashtra (India)

2009-12-15

10

Mn–ferrite nanoparticles via reverse microemulsions: synthesis and characterization  

Microsoft Academic Search

Mn–ferrite nanoparticles were synthesized by thermal treatment at 800 °C of manganese and iron oxo-hydroxides obtained via\\u000a water-in-oil microemulsions consisting of n-hexanol as continuous phase, cetyl trimethyl ammonium bromide (CTAB) as the cationic surfactant and aqueous solutions of\\u000a metal salts and precipitant agent (tetramethyl ammonium hydroxide) as reagents. Nanoparticles were synthesized using a multi-microemulsion\\u000a approach. Two different co-precipitation routes are described

Alessandra Scano; Guido Ennas; Francesca Frongia; Aurelio La Barbera; M. Arturo López-Quintela; Giaime Marongiu; Giorgio Paschina; Davide Peddis; Martina Pilloni; Carlos Vázquez-Vázquez

2011-01-01

11

Aqueous ferrofluids based on manganese and cobalt ferrites  

Microsoft Academic Search

Synthesis of two new aqueous ferrofluids is performed chemically according to Massart's procedure. Manganese and cobalt ferrite magnetic particles are precipitated and treated in order to obtain colloidal sols by creating a charge density on their surface. Such “ionic” ferrofluids can be prepared in an acidic (after a treatment by ferric nitrate) or in an alkaline medium at a concentration

Francisco Augusto Tourinho; Raymonde Franck; René Massart

1990-01-01

12

Ionization Ability of Manganese Nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese oxide nanoparticles (Mn-O NPs) were prepared through our novel method as reagents for laser desorption/ionization mass spectrometry (LDI-MS). Through the control of the reaction time in the chemical preparation method (0.5, 1, and 5 h), we succeeded in preparing three different types of manganese oxide particles. The particles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and DC magnetization measurements. These characterization results indicated that the manganese ions oxidized in aqueous alkaline solution, and that the spinel structure was retained for the Mn3O4 phase, which then gradually changed into the MnO2 phase. The mass spectra of substance P (MW = 1347.6) were measured by MALDI-TOF mass spectrometry with Mn-O NPs. The Mn-O NPs that reacted with 3-aminopropyltriethoxysilane(?-APTES) for 1 h or 5 h had higher ionization abilities than those reacted for 0.5 h. These different abilities are attributed to the different crystal structures of the prepared manganese oxides.

Hiroki, Tomoyuki; Shigeoka, Daiki; Kimura, Shinji; Mashino, Toshiyuki; Taira, Shu; Ichiyanagi, Yuko

2011-05-01

13

Microwave Resonance and Relaxation of Excess-Iron Manganese Ferrites  

Microsoft Academic Search

FMR measurements at 9.3 GHz have been made on single crystal disks of manganese ferrites with resistivities of the order of 0.1 \\\\varOmegacm (300 K), for various values of thickness. Comparison of the data with calculated absorption formulae indicates that an appreciable influence of skin depth effect remains until the thickness becomes as small as about 40 mum. This means

Yoshiyuki Watanabe

1973-01-01

14

Synthesis, characterization, optical and sensing property of manganese oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese oxide nanoparticles were prepared by thermal decomposition of manganese oxalate. Manganese oxalate was synthesized by reacting 1:1 mole ratio of manganese acetate and ammonium oxalate along with sodium dodecyl sulfate (SDS). The structural characterization of manganese oxalate and manganese oxide nanoparticles was analyzed by XRD. The XRD spectrum confirms the crystal structure of the manganese oxide and manganese oxalate. In addition, the average grain size, lattice parameter values were also calculated using XRD spectrum. Moreover, the diffraction peaks were broadened due to the smaller size of the particle. The band gap of manganese oxide was calculated from optical absorption, which was carried out by DRS UV-Visible spectroscopy. The morphology of manganese oxide nanoparticles was analyzed by SEM images. The FT-IR analysis confirms the formation of the manganese oxide from manganese oxalate nanoparticles. The electrochemical sensing behavior of manganese oxide nanoparticles were investigated using hydrogen peroxide by cyclic voltammetry.

Manigandan, R.; Suresh, R.; Giribabu, K.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

2014-01-01

15

Magnetic Characterization of Ferrite Nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles (NPs) of different compositions (FeO/Fe3O4, g-Fe2O3, FePt, and CoFe2O4) have been synthesized using high temperature organometallic routes described elsewhere. NPs (16.6 nm in diameter) of a mixed FeO/Fe3O4 (wuestite/magnetite) composition were prepared by thermal decomposition or iron oleate in the presence of oleic acid as a surfactant in dodocane at 370C in argon atmosphere. After the thermal treatment of the reaction solution at 200 C under air for 2 hours these NPs are transformed into maghemite (g-Fe2O3), the magnetization of which is significantly enhanced. NPs of CoFe2O4 (8 nm) have been prepared by simultaneous decomposition of Co(II) and Fe(III) acetylacetonates in the presence of oleic acid and oleylamine. The X-ray diffraction profile of these NPs is characteristic of cobalt ferrite. Alternatively, alloyed 1.8 nm FePt NPs prepared by simultaneous decomposition of Fe and Pt acetylacetonates in the reductive environment demonstrate a completely disordered structure, which is reflected in their magnetic properties. SQUID magnetometry was used to measure the magnetization of NPs at high and low temperatures. Zero-field cooling and field-cooling measurements were taken to demonstrate superparamagnetic behavior and an associated blocking temperature.

Bryan, Matthew; Sokol, Paul; Gumina, Greg; Bronstein, Lyudmila; Dragnea, Bogdan

2011-03-01

16

Magnetocaloric phenomena in Mg-ferrite nanoparticles  

Microsoft Academic Search

A comparative study of magnetocaloric effect (MCE) in superparamagnetic (SPM) regime is reported in two different types of magnesium ferrite nanostructures. The samples were prepared either by microemulsion method as MgFe2O4 nanoparticles encapsulated in amorphous SiO2, or as matrix-less nanoparticles using hydrothermal synthesis in supercritical water conditions. The particle diameter in all prepared samples was obtained from XRD measurements and

S. Burianova; J. Poltierova-Vejpravova; P. Holec; J. Plocek

2010-01-01

17

Magnetocaloric effect (MCE) in Nickel Ferrite nanoparticles  

Microsoft Academic Search

We report on the magneto caloric effect (MCE) in a Nickel ferrite (NiFe2O4) nanoparticle system. The nanoparticles were synthesized using chemical co-precipitation. Extensive characterization of structural and magnetic properties was done using XRD, TEM, DC and AC magnetization, and transverse susceptibility. The change in entropy was calculated using the thermodynamic Maxwell relation from the family of M-H curves taken at

J. Gass; M. B. Morales; N. A. Frey; M. J. Miner; S. Srinath; H. Srikanth

2007-01-01

18

Magnetocaloric effect (MCE) in ferrite nanoparticles  

Microsoft Academic Search

Enhancement of the magnetocaloric effect (MCE) in nanostructured materials is important for refrigeration applications particularly in potential spot cooling of MEMS and NEMS devices. We have investigated MCE in various classes of polydisperse and monodisperse soft ferrite nanoparticles with different blocking characteristics. Our observations indicate that in some systems, surface properties such as spin disorder and anisotropy lead to considerable

James Gass; Hariharan Srikanth

2008-01-01

19

Low temperature chemical synthesis of ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrite nanoparticles of Ni0.4Zn0.6-xMnxFe2O4 where x varies from 0 to 0.25 in steps of 0.05 using metal nitrates were prepared by low temperature sol-gel autocombustion method in citric acid matrix. XRD patterns of all the samples exhibit spinel crystal structures and the crystallite sizes estimated using Scherrer equation have been found to be about 30 nm. TEM measurements on these nanoparticles showed the particle sizes to be around 32 nm which are in conformity with the crystallite sizes obtained through XRD. The magnetic measurements carried out using VSM on these NiZn ferrite nanoparticles showed good magnetic performance with Mn substitutions. Deviations, if any, in magnetic properties are attributed to the increased degree of inversion in cationic distributions and also to the spin disorder at the surfaces which contributes to decreased magnetic strength of the cations present in different lattice sites.

Ramesh, S.; Rao, S. N. R.; Rao, B. Parvatheeswara; Subba Rao, P. S. V.

2012-07-01

20

State of adsorption layers of fatty acids on the surfaces of iron, manganese, and copper ferrites  

NASA Astrophysics Data System (ADS)

States of adsorbed substances in surface layers arising during the adsorption of oleic, linoleic, and linolenic acids from carbon tetrachloride, heptane, and cyclohexane solutions on the surfaces of iron, manganese, and copper ferrites, are investigated. Adsorption isotherms and two-dimensional state diagrams of surface layers of iron, manganese, and copper ferrites are obtained experimentally. It is shown that the adsorption of fatty acids from solutions in organic solvents proceeds via filling the volume of the ferrites' porous space with adsorption solutions, while the state of ferrite surface layers changes due to the structural rearrangement of adsorption solutions upon an increase in solute concentration.

Balmasova, O. V.; Ramazanova, A. G.; Korolev, V. V.

2012-07-01

21

Cation Occupancy Determination in Manganese Zinc Ferrites using Fourier Transform Infrared Spectroscopy  

SciTech Connect

The magnetic and electric properties of ferrites are influenced by the cation distribution within the crystalline spinel lattice. Methods such as extended x-ray-absorption fine structure (EXAFS) have been used to determine cation occupancies within the crystalline structure of materials such as manganese zinc ferrite (MZFO); however, it is not practical to be used for daily analysis. Fourier transform infrared (FTIR) spectroscopy is another technique which has the potential to determine cation occupancy while offering speed and convenience. In the literature it has been demonstrated that in ferrite systems FTIR data can be correlated to cation percentages when comparing tetrahedral (Td) and octahedral (Oh) sites. FTIR spectra were collected on a series of MZFO nanoparticles in the range from 200 to 600 cm-1 and two absorbance peaks were observed. The first absorption region shifted with changing sample composition as calculated from transmission EXAFS experiments and elemental analysis. The data was normalized to the maximum of the peak of interest and the shifts were correlated to cation occupancy.

Shultz,M.; Carpenter, E.; Morrison, S.; Calvin, S.

2006-01-01

22

Lithium ferrite nanoparticles for ferrofluid applications  

NASA Astrophysics Data System (ADS)

Nanoparticles of Lithium ferrite in the particle size range of 10 nm have been prepared by a citrate precursor method at a relatively low temperature of 200°C. The particles show characteristic infra red (IR) spectrum of lithium ferrite and broadened X-ray diffraction (XRD) patterns typical of the nanoparticle nature. The sample decomposed at 200°C has the ?-LiFe 5O 8 type (a disordered type of spinel) structure which on annealing at 350°C transforms to the ?-LiFe 5O 8 type (an ordered type spinel) structure as shown by both IR spectra and XRD studies. Magnetization curves indicate a particle size distribution consisting of both ferromagnetic particles and a superparamagnetic fraction. With 4 ?Ms values of 2000 G these particles could be useful for applications in certain low magnetization ferrofluids.

Sankaranarayanan, V. K.; Prakash, Om; Pant, R. P.; Islam, Mohammad

2002-11-01

23

Ferrite nanoparticles for future heart diagnostics  

NASA Astrophysics Data System (ADS)

Normally, CoFe2O4 has been known as ferromagnetic ferrite with a quite large magnetic moment. However, since we aim to inject the particles into the human body, we are also interested in ZnFe2O4 because in the human body, Fe and Zn exist, so that adding ZnFe2O4 is safer. In both cases, the nanoparticles are coated by silica in order to get rid of toxicity. Our main purpose is to test whether these nanoparticles affect the contractile function of heart cells. Our results on rat's heart cells have shown that both Zn and Co ferrites improved the contractility of heart cells. Notably, although both nanoparticles increased contraction and delayed relaxation, Co ferrites induced a greater contraction but with a slower relaxation. We can theoretically argue that the magnetization effects of the quantum dots have a considerable effect on the pulsating properties of the heart cells. Through this effect, the locally applied magnetic field is able to induce as well as turn on/off various regular beating patterns, thus, resetting the heart beatings.

Hong, Nguyen Hoa; Raghavender, A. T.; Ciftja, O.; Phan, M.-H.; Stojak, K.; Srikanth, H.; Zhang, Yin Hua

2013-08-01

24

Fabrication of Mn-ferrite nanoparticles from MnO colloids.  

PubMed

The reaction mechanism for conversion of MnO nanoparticles to Mn-ferrite nanoparticles was studied, which involved sequential consumption of MnO and the growth of ferrite. The method could be applied to other ferrite nanoparticles including cobalt ferrite. PMID:19885477

Han, Anna; Choi, Donghyuk; Kim, Taehei; Lee, Jei Hee; Kim, Jai Keun; Yoon, Mi Jin; Choi, Kyeong Sook; Kim, Sang-Wook

2009-11-28

25

Growth of highly textured manganese zinc ferrite films on glass substrates  

NASA Astrophysics Data System (ADS)

Highly textured manganese zinc ferrite (Mn0.7Zn0.3Fe2O4) films have been successfully fabricated on glass substrates by pulse laser deposition at relatively low temperatures. Investigations indicated that the strain, which is induced by high deposition rate and the difference of thermal coefficient between the film and glass substrate, is attributed to the growth of textured structure. Growth of highly textured cobalt ferrite film was also achieved using the same method. This work provided a possible technique for fabricating high quality ferrite films on glass substrates.

Waqas, H.; Huang, X. L.; Ding, J.; Fan, H. M.; Ma, Y. W.; Herng, T. S.; Quresh, A. H.; Wei, J. Q.; Xue, D. S.; Yi, J. B.

2010-05-01

26

Ternary manganese ferrite/graphene/polyaniline nanostructure with enhanced electrochemical capacitance performance  

NASA Astrophysics Data System (ADS)

A ternary manganese ferrite/graphene/polyaniline (MGP) nanostructure is designed and synthesized via a facile two-step approach. This nanostructure exhibits outstanding electrochemical performances, such as high specific capacitance (454.8 F g-1 at 0.2 A g-1), excellent rate capability (75.8% capacity retention at 5 A g-1), and good cycling stability (76.4% capacity retention after 5000 cycles at 2 A g-1), which are superior to those of its individual components (manganese ferrite, reduced-graphene oxide, polyaniline) and corresponding binary hybrids (manganese ferrite/graphene (MG), manganese ferrite/polyaniline (MP), and graphene/polyaniline (GP). A symmetric supercapacitor device using the as-obtained hybrid has been fabricated and tested. The device exhibits a high specific capacitance of 307.2 F g-1 at 0.1 A g-1 with a maximum energy density of 13.5 W h kg-1. The high electrochemical performance of ternary MGP can be attributed to its well-designed nanostructure and the synergistic effect of the individual components.

Xiong, Pan; Hu, Chenyao; Fan, Ye; Zhang, Wenyao; Zhu, Junwu; Wang, Xin

2014-11-01

27

Effect of intragranular porosity of initial permeability and coercive force in a manganese zinc ferrite  

Microsoft Academic Search

Initial permeability and coercive force are structure sensitive properties which depend upon intragranular porosity. It has been found that in a manganese zinc ferrite the initial permeability varies directly as the separation between intragranular pores and the coercive force varies inversely as the square root of this distance. Assuming reversible motion of the domain wall pinned at the pores, the

G. C. Jain; B. K. Das; R. S. Khanduja; S. C. Gupta

1976-01-01

28

Effect of an Electrostatic Field on Self-Propagating High-Temperature Synthesis of Manganese Ferrite  

Microsoft Academic Search

Using the synthesis of manganese ferrite as an example, it is shown that an electric field causes a significant change in the parameters of heterogeneous combustion, depending on the field strength and application direction. The possible factors determining the end burning of the starting mixture in the applied electric field are considered.

S. M. Busurin; Yu. G. Morozov; M. V. Kuznetsov; S. G. Bakhtamov; M. L. Chernega

2005-01-01

29

Synthesis of manganese nanoparticles in the liquid phase plasma.  

PubMed

The liquid phase plasma reduction method was applied to prepare the polycrystalline manganese nanoparticles from the solution of manganese chloride tetrahydrate. A bipolar pulsed power supply was used to generate discharge in the aqueous solutions. While large size of dendrite-shaped manganese nanoparticles were mostly observed in the initial stage and particle size decreased with discharge time. The particles were dispersed with less and less small particles by the addition of CTAB and anisotropic shapes nanoparticles were mostly observed at long time plasma-treated. Many spots could be seen in the ED pattern for polycrystalline particles. PMID:24205609

Kim, Hwan-Gi; Lee, Heon; Kim, Sun-Jae; Kim, Do-Heyoung; Kim, Jung-Sik; Kang, Sang-Yong; Jung, Sang-Chul

2013-09-01

30

Transformation Characteristics of Ferrite/Carbide Aggregate in Continuously Cooled, Low Carbon-Manganese Steels  

NASA Astrophysics Data System (ADS)

Transformation characteristics and morphological features of ferrite/carbide aggregate (FCA) in low carbon-manganese steels have been investigated. Work shows that FCA has neither the lamellae structure of pearlite nor the lath structure of bainite and martensite. It consists of a fine dispersion of cementite particles in a smooth ferrite matrix. Carbide morphologies range from arrays of globular particles or short fibers to extended, branched, and densely interconnected fibers. Work demonstrates that FCA forms over similar cooling rate ranges to Widmanstätten ferrite. Rapid transformation of both phases occurs at temperatures between 798 K and 973 K (525 °C and 700 °C). FCA reaction is not simultaneous with Widmanstätten ferrite but occurs at temperatures intermediate between Widmanstätten ferrite and bainite. Austenite carbon content calculations verify that cementite precipitation is thermodynamically possible at FCA reaction temperatures without bainite formation. The pattern of precipitation is confirmed to be discontinuous. CCT diagrams have been constructed that incorporate FCA. At low steel manganese content, Widmanstätten ferrite and bainite bay sizes are significantly reduced so that large amounts of FCA are formed over a wide range of cooling rates.

Di Martino, S. F.; Thewlis, G.

2014-02-01

31

Transition metal-substituted cobalt ferrite nanoparticles for biomedical applications.  

PubMed

Transition metals of copper, zinc, chromium and nickel were substituted into cobalt ferrite nanoparticles via a sol-gel route using citric acid as a chelating agent. The microstructure and elemental composition were characterized using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Phase analysis of transition metal-substituted cobalt ferrite nanoparticles was performed via X-ray diffraction. Surface wettability was measured using the water contact angle technique. The surface roughness of all nanoparticles was measured using profilometry. Moreover, thermogravimetric analysis and differential scanning calorimetry were performed to determine the temperature at which the decomposition and oxidation of the chelating agents took place. Results indicated that the substitution of transition metals influences strongly the microstructure, crystal structure and antibacterial property of the cobalt ferrite nanoparticles. PMID:23137676

Sanpo, Noppakun; Berndt, Christopher C; Wen, Cuie; Wang, James

2013-03-01

32

Thermodynamic modelling of the formation of zinc-manganese ferrite spinel in electric arc furnace dust.  

PubMed

Electric arc furnace dust is generated when automobile scrap, containing galvanized steel, is remelted in an electric arc furnace. This dust is considered as a hazardous waste in most countries. Zinc is a major component of the dust and can be of significant commercial value. Typically, the majority of the zinc exists as zinc oxide (ZnO) and as a zinc-manganese ferrite spinel ((Zn(x)Mn(y)Fe(1-x-y))Fe(2)O(4)). The recovery of the zinc from the dust in metal recycling and recovery processes, particularly in the hydrometallurgical extraction processes, is often hindered by the presence of the mixed ferrite spinel. However, there is a paucity of information available in the literature on the formation of this spinel. Therefore, in the present research, the equilibrium module of HSC Chemistry 6.1 was utilized to investigate the thermodynamics of the formation of the spinel and the effect of variables on the amount and the composition of the mixed ferrite spinel. It is proposed that the mixed ferrite spinel forms due to the reaction of iron-manganese particulates with both gaseous oxygen and zinc, at the high temperatures in the freeboard of the furnace above the steel melt. Based on the thermodynamic predictions, methods are proposed for minimizing the formation of the mixed ferrite spinel. PMID:20356673

Pickles, C A

2010-07-15

33

Ferrite Nanoparticles, Films, Single Crystals, and Metamaterials: High Frequency Applications  

SciTech Connect

Ferrite materials have long played an important role in power conditioning, conversion, and generation across a wide spectrum of frequencies (up to ten decades). They remain the preferred magnetic materials, having suitably low losses, for most applications above 1 MHz, and are the only viable materials for nonreciprocal magnetic microwave and millimeter-wave devices (including tunable filters, isolators, phase shifters, and circulators). Recently, novel processing techniques have led to a resurgence of research interest in the design and processing of ferrite materials as nanoparticles, films, single crystals, and metamaterials. These latest developments have set the stage for their use in emerging technologies that include cancer remediation therapies such as magnetohyperthermia, magnetic targeted drug delivery, and magneto-rheological fluids, as well as enhanced magnetic resonance imaging. With reduced dimensionality of nanoparticles and films, and the inherent nonequilibrium nature of many processing schemes, changes in local chemistry and structure have profound effects on the functional properties and performance of ferrites. In this lecture, we will explore these effects upon the fundamental magnetic and electronic properties of ferrites. Density functional theory will be applied to predict the properties of these ferrites, with synchrotron radiation techniques used to elucidate the chemical and structural short-range order. This approach will be extended to study the atomic design of ferrites by alternating target laser-ablation deposition. Recently, this approach has been shown to produce ferrites that offer attractive properties not found in conventionally grown ferrites. We will explore the latest research developments involving ferrites as related to microwave and millimeter-wave applications and the attempt to integrate these materials with semiconductor materials platforms.

Harris,V.

2006-01-01

34

Preparation and characterization of manganese ferrite-based magnetic liposomes for hyperthermia treatment of cancer  

NASA Astrophysics Data System (ADS)

Comparative evaluation of two different methods of magnetic liposomes preparation, namely thin film hydration (TFH) and double emulsion (DE) with different molar ratios of egg-phosphatidyl choline (egg-PC) and cholesterol using lauric acid coated manganese ferrite-based aqueous magnetic fluid, is reported. TFH was found to be a better method of encapsulation and TFH 2:1 (egg-PC: cholesterol) magnetic liposomes showed the highest encapsulation efficiency and comparable heating ability to that of magnetic fluids. Stealth TFH 2:1 magnetic liposomes containing DSPE-PEG 2000 were three-fold more cytocompatible as compared to the magnetic fluid. Stealth TFH 2:1 manganese ferrite-based magnetic liposomes might be useful for hyperthermia treatment of cancer.

Pradhan, Pallab; Giri, Jyotsnendu; Banerjee, Rinti; Bellare, Jayesh; Bahadur, Dhirendra

2007-04-01

35

Preparation and characterization of manganese ferrite-based magnetic liposomes for hyperthermia treatment of cancer  

Microsoft Academic Search

Comparative evaluation of two different methods of magnetic liposomes preparation, namely thin film hydration (TFH) and double emulsion (DE) with different molar ratios of egg-phosphatidyl choline (egg-PC) and cholesterol using lauric acid coated manganese ferrite-based aqueous magnetic fluid, is reported. TFH was found to be a better method of encapsulation and TFH 2:1 (egg-PC: cholesterol) magnetic liposomes showed the highest

Pallab Pradhan; Jyotsnendu Giri; Rinti Banerjee; Jayesh Bellare; Dhirendra Bahadur

2007-01-01

36

Thermal Growth and Performance of Manganese Cobaltite Spinel Protection Layers on Ferritic Stainless Steel SOFC Interconnects  

Microsoft Academic Search

To protect solid oxide fuel cells (SOFCs) from chromium poisoning and improve metallic interconnect stability, manganese cobaltite spinel protection layers with a nominal composition of Mn1.5Co1.5O4 were thermally grown on Crofer22 APU, a ferritic stainless steel. Thermal, electrical and electrochemical investigations indicated that the spinel protection layers not only significantly decreased the contact area specific resistance (ASR) between a LSF

Zhenguo Yang; Guanguang Xia; Steven P. Simner; Jeffry W. Stevenson

2005-01-01

37

Mössbauer spectroscopic characterization of manganese and cobalt ferrite ferrofluids  

NASA Astrophysics Data System (ADS)

Aqueous ferrofluids based on Mn and Co ferrites have been synthesized by a novel method. Mössbauer spectra of dried samples (average particle diameter ? 10 nm) were measured in the 77 340 K temperature range. CoFe2O4 spectra show no superparamagnetic (SP) relaxation, in accordance with the high magnetic anisotropy of this compound. MnFe2O4 spectra exhibit SP relaxation, from which an effective K=(8±3)×104 J/m3 is estimated. This value represents a 20× enhancement over intrinsic magnetocrystalline anisotropy.

Rechenberg, H. R.; Tourinho, F. A.

1991-11-01

38

Curie Temperature and Magnetostriction of Manganese doped Cobalt Ferrite Magnetostrictive Material  

NASA Astrophysics Data System (ADS)

Cobalt ferrite and its composites have a unique combination of high permeability and high magneto-elastic coupling that make them ideal for magnetostrictive stress-sensing and adaptive "smart materials" applications. However composites made of the parent cobalt ferrite can show an undesirable magnetomechanical hysteresis below 60^oC. We report results of an investigation of a new family of CoMn_xFe_2-xO_4, compounds in which we have studied the variation of magnetization with temperature and the variation of magnetostriction with magnetic field for various chemical compositions. The substitution of manganese for iron dramatically lowers the Curie temperature by up to 250^oC, while still maintaining a high magnetostriction. The results indicate the possibility of controlling the magnetoelastic properties of cobalt ferrite composites through control of chemical composition. Substitution of manganese for cobalt was found to be far less effective. This research was supported by the National Aeronautical and Space Administration (NASA) under award No NAG-1-02098.

Paulsen, J. A.; Ring, A. P.; Lo, C. C. H.; Snyder, J. E.; Jiles, D. C.

2004-03-01

39

Ultrasonic cavitation induced water in vegetable oil emulsion droplets--a simple and easy technique to synthesize manganese zinc ferrite nanocrystals with improved magnetization.  

PubMed

In the present investigation, synthesis of manganese zinc ferrite (Mn(0.5)Zn(0.5)Fe(2)O(4)) nanoparticles with narrow size distribution have been prepared using ultrasound assisted emulsion (consisting of rapeseed oil as an oil phase and aqueous solution of Mn(2+), Zn(2+) and Fe(2+) acetates) and evaporation processes. The as-prepared ferrite was nanocrystalline. In order to remove the small amount of oil present on the surface of the ferrite, it was subjected to heat treatment at 300 °C for 3h. Both the as-prepared and heat treated ferrites have been characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), TGA/DTA, transmission electron microscopy (TEM) and energy dispersion X-ray spectroscopy (EDS) techniques. As-prepared ferrite is of 20 nm, whereas the heat treated ferrite shows the size of 33 nm. In addition, magnetic properties of the as-prepared as well as the heat treated ferrites have also been carried out and the results of which show that the spontaneous magnetization (?(s)) of the heat treated sample (24.1 emu/g) is significantly higher than that of the as-synthesized sample (1.81 emu/g). The key features of this method are avoiding (a) the cumbersome conditions that exist in the conventional methods; (b) usage of necessary additive components (stabilizers or surfactants, precipitants) and (c) calcination requirements. In addition, rapeseed oil as an oil phase has been used for the first time, replacing the toxic and troublesome organic nonpolar solvents. As a whole, this simple straightforward sonochemical approach results in more phase pure system with improved magnetization. PMID:22113061

Sivakumar, Manickam; Towata, Atsuya; Yasui, Kyuichi; Tuziuti, Toru; Kozuka, Teruyuki; Iida, Yasuo; Maiorov, Michail M; Blums, Elmars; Bhattacharya, Dipten; Sivakumar, Neelagesi; Ashok, M

2012-05-01

40

Cobalt-ferrite nanoparticles: Structure, cation distributions, and magnetic properties  

NASA Astrophysics Data System (ADS)

Cobalt-ferrite nanoparticles have been synthesized in water-in-oil microemulsions (reversed micelles) with varying cation composition. The microenvironment provides a template effect that controls the size and particle shape. Transmission electron microscopy reveals that the particles are nanospheres with particle size ranging from 12 to 18 nm. X-ray diffraction results indicate that at low Co2+:Fe2+ ratio (1:10 and 1:5) in the precursor, the particles retain an essentially ferrite structure (?-Fe2O3). However, the cobalt-ferrite phase (CoFe2O4) forms upon further increase of the Co2+ content. The materials are found to exhibit superparamagnetism. The blocking temperatures and coercivities are dependent on the Co2+:Fe2+ ratio in the system.

Li, Sichu; John, Vijay T.; O'Connor, Charles; Harris, Vincent; Carpenter, Everett

2000-05-01

41

Size-dependent magnetic properties of calcium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The union of nanotechnology with the other fields of science heralds the influx of many newer and better technologies, with the capability to revolutionize the human life. In the present work, calcium ferrite nanoparticles were synthesized by conventional sol-gel method and were characterised by X-ray diffraction, Transmission electron microscope, Vibrating sample magnetometer and Fourier transform infrared spectroscope. The synthesized nanoparticles were calcined at different temperatures and their magnetic behaviour was studied. The synthesized nanoparticles calcined at 900 °C were formed in the shape of capsules and exhibited mixed characteristics of ferrimagnetic and paramagnetic grains with magnetic saturation of 0.85 emu/g whereas nanoparticles calcined at 500 °C were spherical in shape and exhibited superparamagnetic characteristics with saturation magnetization of 37.67 emu/g.

Khanna, Lavanya; Verma, N. K.

2013-06-01

42

Magnetic properties of substituted strontium ferrite nanoparticles and thin films  

NASA Astrophysics Data System (ADS)

SrFe 12-x(Zr 0.5Mg 0.5) xO 19 nanoparticles and thin films with x=0-2.5 were synthesized by a sol-gel method on thermally oxidized silicon wafer (Si/SiO 2). Structural and magnetic characteristics of synthesized samples were studied employing x-rays diffraction (XRD), transmission electron microscopy (TEM), magnetic susceptometer, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). TEM micrographs display that the narrow size distribution of ferrite nanoparticles with average particle size of 50 nm were fabricated. Fitting obtained data of effective magnetic susceptibility by Vogel-Fulcher law confirms the existence of strong magnetic interaction among fine particles. XRD patterns and FE-SEM micrographs demonstrated that single phase c-axis hexagonal ferrite films with rather narrow grain size distribution were obtained. AFM micrographs exhibited that the surface roughness increases with an increase in Zr-Mg content. It was found from the VSM graphs that with an increase in substitution contents the coercivity decreases, while the saturation of magnetization increases. The Henkle plots confirms the existence of exchange coupling among nano-grain in ferrite thin films.

Ghasemi, Ali

2012-04-01

43

Chemisorption of cyanogen chloride by spinel ferrite magnetic nanoparticles.  

PubMed

Spinel ferrite magnetic nanoparticles, MnFe2O4, NiFe2O4, and CoFe2O4, were synthesized and used as gas-phase adsorbents for the removal of cyanogen chloride from dry air. Fixed-bed adsorption breakthrough experiments show adsorption wave behavior at the leading edge of the breakthrough curve that is not typical of physically adsorbed species. Fourier transform infrared spectroscopy (FTIR) results indicate that CK is reacting with the spinel ferrite surface and forming a carbamate species. The reaction is shown to be a function of the hydroxyl groups and adsorbed water on the surface of the particles as well as the metallic composition of the particles. The surface reaction decreases the remnant and saturation magnetism of the MnFe2O4 and CoFe2O4 particles by approximately 25%. PMID:23540752

Glover, T Grant; DeCoste, Jared B; Sabo, Daniel; Zhang, Z John

2013-05-01

44

Preparation of cobalt-ferrite nanoparticles within a biopolymer template  

NASA Astrophysics Data System (ADS)

Using an in-situ co-precipitation reaction from solid dissolutions of stoichiometric amounts of Fe (III) and Co (II) inorganic salts, it was prepared highly loaded nanocomposites (as high as 75% w/w) of cobalt-ferrite nanoparticles within a chitosan matrix, with particle size of about 7 nm, narrow particle size distribution and superparamagnetic character. Nanocomposite samples were characterized by high resolution transmission electron microscopy (HRTEM), UV-vis spectrometry and magnetic measurements by SQUID, using magnetization-field dependent, M(H), and magnetization-temperature dependent, M(T), studies.

Garza, Marco; González, Virgilio; Torres-Castro, Alejandro; Hinojosa, Moisés; Ortíz, Ubaldo

2008-03-01

45

Thermal Growth and Performance of Manganese Cobaltite Spinel Protection Layers on Ferritic Stainless Steel SOFC Interconnects  

SciTech Connect

To protect solid oxide fuel cells (SOFCs) from chromium poisoning and improve metallic interconnect stability, manganese cobaltite spinel protection layers with a nominal composition of Mn1.5Co1.5O4 were thermally grown on Crofer22 APU, a ferritic stainless steel. Thermal, electrical and electrochemical investigations indicated that the spinel protection layers not only significantly decreased the contact area specific resistance (ASR) between a LSF cathode and the stainless steel interconnect, but also inhibited the sub-scale growth on the stainless steel by acting as a barrier to the inward diffusion of oxygen. A long-term thermal cycling test demonstrated excellent structural and thermomechanical stability of these spinel protection layers, which also acted as a barrier to outward chromium cation diffusion to the interconnect surface. The reduction in the contact ASR and prevention of Cr migration achieved by application of the spinel protection layers on ferritic stainless steel resulted in improved stability and electrochemical performance of SOFCs.

Yang, Zhenguo; Xia, Guanguang; Simner, Steven P.; Stevenson, Jeffry W.

2005-08-01

46

Magnetocaloric Effect in Nanoparticle Systems and Clathrates  

Microsoft Academic Search

We report the magnetocaloric effect (MCE) in cobalt ferrite, manganese ferrite, and nickel ferrite nanoparticle systems and also the first observation of a large MCE in Eu8Ga16Ge30 clathrate compounds. The ferrite nanoparticles were synthesized using organometallic precursors in a wet chemical technique and characterized by XPS and XRD. Change in entropy (deltaS^mag) was calculated using the Maxwell relation from the

D. J. Rebar; J. Gass; S. Srinath; H. Srikanth; G. S. Nolas

2006-01-01

47

Permeability and microstructure of manganese modified lithium ferrite prepared by sol–gel auto-combustion method  

Microsoft Academic Search

A series of manganese modified lithium ferrite powders, Li0.5Fe2.5O4 with different content of Mn (0, 0.05, 0.1, 0.15, 0.20, 0.25) were directly prepared by a novel sol–gel auto-combustion method at room temperature. The average particle sizes of as-synthesized powders were 50 nm and exhibited high activity and homogenous chemical composition. The lithium ferrites prepared by as-synthesized powders can be sintered

Xiwei Qi; Ji Zhou; Zhenxing Yue; Zhilun Gui; Longtu Li

2003-01-01

48

Cytotoxicity of nickel zinc ferrite nanoparticles on cancer cells of epithelial origin  

PubMed Central

In this study, in vitro cytotoxicity of nickel zinc (NiZn) ferrite nanoparticles against human colon cancer HT29, breast cancer MCF7, and liver cancer HepG2 cells was examined. The morphology, homogeneity, and elemental composition of NiZn ferrite nanoparticles were investigated by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy, respectively. The exposure of cancer cells to NiZn ferrite nanoparticles (15.6–1,000 ?g/mL; 72 hours) has resulted in a dose-dependent inhibition of cell growth determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The quantification of caspase-3 and -9 activities and DNA fragmentation to assess the cell death pathway of the treated cells showed that both were stimulated when exposed to NiZn ferrite nanoparticles. Light microscopy examination of the cells exposed to NiZn ferrite nanoparticles demonstrated significant changes in cellular morphology. The HepG2 cells were most prone to apoptosis among the three cells lines examined, as the result of treatment with NiZn nanoparticles. In conclusion, NiZn ferrite nanoparticles are suggested to have potential cytotoxicity against cancer cells.

Al-Qubaisi, Mothanna Sadiq; Rasedee, Abdullah; Flaifel, Moayad Husein; Ahmad, Sahrim HJ; Hussein-Al-Ali, Samer; Hussein, Mohd Zobir; Eid, Eltayeb EM; Zainal, Zulkarnain; Saeed, Mohd; Ilowefah, Muna; Fakurazi, Sharida; Isa, Norhaszalina Mohd; Zowalaty, Mohamed Ezzat El

2013-01-01

49

Dielectric properties of cobalt ferrite nanoparticles in ultrathin nanocomposite films.  

PubMed

Multilayered nanocomposite films (thickness 50-90 nm) of cobalt ferrite nanoparticles (np-CoFe2O4, 18 nm) were deposited on top of interdigitated microelectrodes by the layer-by-layer technique in order to study their dielectric properties. For that purpose, two different types of nanocomposite films were prepared by assembling np-CoFe2O4 either with poly(3,4-ethylenedioxy thiophene):poly(styrene sulfonic acid) or with polyaniline and sulfonated lignin. Despite the different film architectures, the morphology of both was dominated by densely-packed layers of nanoparticles surrounded by polyelectrolytes. The dominant effect of np-CoFe2O4 was also observed after impedance spectroscopy measurements, which revealed that dielectric behavior of the nanocomposites was largely influenced by the charge transport across nanoparticle-polyelectrolyte interfaces. For example, nanocomposites containing np-CoFe2O4 exhibited a single low-frequency relaxation process, with time constants exceeding 15 ms. At 1 kHz, the dielectric constant and the dissipation factor (tan ?) of these nanocomposites were 15 and 0.15, respectively. These values are substantially inferior to those reported for pressed pellets made exclusively of similar nanoparticles. Impedance data were further fitted with equivalent circuit models from which individual contributions of particle's bulk and interfaces to the charge transport within the nanocomposites could be evaluated. The present study evidences that such nanocomposites display a dielectric behavior dissimilar from that exhibited by their individual counterparts much likely due to enlarged nanoparticle-polyelectrolyte interfaces. PMID:24145704

Alcantara, Gustavo B; Paterno, Leonardo G; Fonseca, Fernando J; Pereira-da-Silva, Marcelo A; Morais, Paulo C; Soler, Maria A G

2013-12-01

50

Adsorption isotherms of linoleic and linolenic acids from solutions in carbon tetrachloride on surfaces of highly dispersed manganese and copper ferrites  

NASA Astrophysics Data System (ADS)

A comparative study of adsorption-desorption isotherms of linoleic and linolenic acids from solutions in carbon tetrachloride on surfaces of manganese and copper ferrites is performed by means of equilibrium adsorption. Adsorption isotherms of fatty acids are described in terms of the theory of volume filling of micropores, and the values of the limiting adsorption, the characteristic adsorption energy, and the pore space volume are calculated. It is established that the limiting adsorption values of linoleic and linolenic acids from solutions in carbon tetrachloride on a copper ferrite surface are higher than on a manganese ferrite surface. It is shown that the adsorption-desorption isotherms have a hysteresis loop.

Balmasova, O. V.; Korolev, V. V.; Ramazanova, A. G.

2012-04-01

51

Direct dyes removal using modified magnetic ferrite nanoparticle  

PubMed Central

The magnetic adsorbent nanoparticle was modified using cationic surface active agent. Zinc ferrite nanoparticle and cetyl trimethylammonium bromide were used as an adsorbent and a surface active agent, respectively. Dye removal ability of the surface modified nanoparticle as an adsorbent was investigated. Direct Green 6 (DG6), Direct Red 31 (DR31) and Direct Red 23 (DR23) were used. The characteristics of the adsorbent were studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of adsorbent dosage, initial dye concentration and salt was evaluated. In ternary system, dye removal of the adsorbent at 90, 120, 150 and 200 mg/L dye concentration was 63, 45, 30 and 23% for DR23, 97, 90, 78 and 45% for DR31 and 51, 48, 42 and 37% for DG6, respectively. It was found that dye adsorption onto the adsorbent followed Langmuir isotherm. The adsorption kinetic of dyes was found to conform to pseudo-second order kinetics.

2014-01-01

52

Effect of combustion rate and annealing temperature on structural and magnetic properties of manganese substituted nickel and zinc ferrites  

NASA Astrophysics Data System (ADS)

An auto-combustion method was used to prepare manganese substituted nickel and zinc ferrites under three different fuel ratios (50%, 75% and 100%). The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectrum (EDX). The combustion reaction time of 50% fuel ratio is longer than the other ratios (75% and 100%). The smallest range of particles of about 12 to 33 nm for Mn-Zn ferrites and 20-60 nm for Mn-Ni ferrites were achieved only at 50% fuel ratio. The external morphology of the samples is visualized through SEM. The microstructure and particle size of the annealed sample were analyzed by TEM. The composition of the elements presence in the samples was determined by EDX spectrum. Also, the magnetic behavior of the samples annealed at 600 °C and 900 °C was investigated by using a vibrating sample magnetometer (VSM).

Kumar, E. Ranjith; Jayaprakash, R.

2013-12-01

53

Synthesis and characterization of silica coated potassium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Silica coated potassium ferrite nanoparticles (KFeO2 NPs) have been synthesized by conventional stöber process. The orthorhombic structure of KFeO2 NPs has been retained even after silica coating, only a slight variation has been observed in the angle range of 20°-25° (occurring due to amorphous silica), as shown by the X-ray diffraction pattern. The crystallite size using Scherrer's formula of bare and silica coated KFeO2 NPs has been calculated to be 21.0 nm and 22.5 nm, respectively. The spherical formation of silica coated KFeO2 NPs has been revealed by transmission electron microscope. Presence of silica on KFeO2 NPs has been confirmed by energy dispersive X-ray spectroscope. A small magnetic saturation value of 3.67emu/g has been observed in the vibrating sample magnetometer analysis.

Khanna, Lavanya; Verma, N. K.

2013-06-01

54

Preparation and characterization of complex ferrite nanoparticles by a polymer-pyrolysis route  

Microsoft Academic Search

The polymer-pyrolysis route used in this work was to synthesize the copolymeric precursor of the mixed metallic ions and then\\u000a to pyrolyze the precursor into complex spinel ferrite nanoparticles. Thermogravimetric analysis (TGA) showed that the complex\\u000a ferrite nanoparticles could be obtained by calcination of their precursors at 500°C. The structures, elemental analyses and\\u000a particle morphology of the as-calcined products were

Xian-Ming Liu; Shao-Yun Fu; Hong-Mei Xiao; Lu-Ping Zhu

2007-01-01

55

Preparation and characterization of the cobalt ferrite nano-particles by reverse coprecipitation  

NASA Astrophysics Data System (ADS)

In this paper, cobalt ferrite nano-particles were rapidly prepared using a reverse coprecipitation method. The effects of pH value, aging time, aging temperature and calcination temperature were studied by VSM, XRD and TEM. The results presented that the conditions to obtain the cobalt ferrite nano-particles with a perfect cubic spinel ferrite type structure are the pH value of 12.00, aging time of 60 min, aging temperature of 92 °C and calcination temperature of 800 °C. The crystallite size of cobalt ferrite increased with increasing the aging and calcination temperature. The saturation magnetization of cobalt ferrite increased with increasing the aging and calcination temperature. The VSM analysis demonstrated that the optimum sample has a high saturation magnetization and proper coercivity, 72.95 emu/g and 717 Oe, respectively. Furthermore, the particle size estimated from the TEM was seen to be larger than that observed from the XRD analysis.

Huixia, Feng; Baiyi, Chen; Deyi, Zhang; Jianqiang, Zhang; Lin, Tan

2014-04-01

56

Substitution of manganese and iron into hydroxyapatite: Core/shell nanoparticles  

SciTech Connect

The bioceramics, hydroxyapatite (HAP), is a material which is biocompatible to the human body and is well suited to be used in hyperthermia applications for the treatment of bone cancer. We investigate the substitution of iron and manganese into the hydroxyapatite to yield ceramics having the empirical formula Ca{sub 9.4}Fe{sub 0.4}Mn{sub 0.2}(PO{sub 4}){sub 6}(OH){sub 2}. The samples were prepared by the co-precipitation method. The formation of the nanocrystallites in the HAP structure as the heating temperatures were raised to obtain a glass-ceramic system are confirmed by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and electron spin resonance (ESR). TEM images show the core/shell structure of the nanoparticles, with the core being formed by the ferrites and the shell by the hydroxyapatite. The ED patterns indicate the nanoparticles formed at 500 deg. C have an amorphous structure while the nanoparticles formed at 1000 deg. C are crystalline. ESR spectroscopy indicated that the Fe{sup 3+} ions have a g-factor of 4.23 and the Mn{sup 2+} ions have a g-factor of 2.01. The values of the parameters in the spin Hamiltonian which describes the interaction between the transition metal ions and the Ca{sup 2+} ions, indicate that the Mn{sup 2+} ion substitute into the Ca{sup 2+} sites which are ninefold coordinated, i.e., the Ca(1) sites.

Pon-On, Weeraphat; Meejoo, Siwaporn [Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Tang, I.-Ming [Department of Physics, Faculty of Science, Mahidol University, Institute of Science and Technology for Research and Development, Salaya Campus, Mahidol University, Nakorn Pathom 71730 (Thailand)], E-mail: scimt@mahidol.ac.th

2008-08-04

57

Embryotoxicity of cobalt ferrite and gold nanoparticles: a first in vitro approach.  

PubMed

Nanoparticles (NPs) are emerging as promising biomedical tools thanks to their peculiar characteristics. Our purpose was to investigate the embryotoxicity of cobalt ferrite and gold NPs through the Embryonic Stem Cell Test (EST). The EST is an in vitro standard assay, which permits to classify substances as strongly, weakly or non-embryotoxic. Due to the particular physical-chemical nature of nanoparticles, we introduced a modification to the standard protocol exposing the Embryonic Stem Cells (ES-D3) to nanoparticles only during the first 5 days of the assay. Moreover, we proposed a method to discriminate and compare the embryotoxicity of the substances within the weakly embryotoxic range. Our ID(50) results permit to classify cobalt ferrite nanoparticles coated with gold and silanes as non-embryotoxic. The remaining nanoparticles have been classified as weakly embryotoxic in this decreasing order: gold salt (HAuCl(4).3H(2)O)>cobalt ferrite salt (CoFe(2)O(4))>cobalt ferrite nanoparticles coated with silanes (Si-CoFe)>gold nanoparticles coated with hyaluronic acid (HA-Au). PMID:20566333

Di Guglielmo, Claudia; López, David Ramos; De Lapuente, Joaquín; Mallafre, Joan Maria Llobet; Suàrez, Miquel Borràs

2010-09-01

58

Dielectric relaxations and alternating current conductivity in manganese substituted cobalt ferrite  

NASA Astrophysics Data System (ADS)

Manganese (Mn) substituted cobalt ferrites (CoFe2-xMnxO4, referred to CFMO) have been synthesized by the solid state reaction method and their dielectric properties and ac conductivity have been evaluated as a function of applied frequency and temperature. X-ray diffraction measurements indicate that CFMO crystallize in the inverse cubic spinel phase with a lattice constant ˜8.38 Å. Frequency dependent dielectric measurements at room temperature obey the modified Debye model with relaxation time of 10-4 s and spreading factor of 0.35(±0.05). The frequency (20 Hz-1 MHz) and temperature (T = 300-900 K) dependent dielectric constant analyses indicate that CFMO exhibit two dielectric relaxations at lower frequencies (1-10 kHz), while completely single dielectric relaxation for higher frequencies (100 kHz-1 MHz). The dielectric constant of CFMO is T-independent up to ˜400 K, at which point increasing trend prevails. The dielectric constant increase with T > 400 K is explained through impedance spectroscopy assuming a two-layer model, where low-resistive grains separated from each other by high-resistive grain boundaries. Following this model, the two electrical responses in impedance formalism are attributed to the grain and grain-boundary effects, respectively, which also satisfactorily accounts for the two dielectric relaxations. The capacitance of the bulk of the grain determined from impedance analyses is ˜10 pF, which remains constant with T, while the grain-boundary capacitance increases up to ˜3.5 nF with increasing T. The tan ? (loss tangent)-T also reveals the typical behavior of relaxation losses in CFMO.

Kolekar, Y. D.; Sanchez, L. J.; Ramana, C. V.

2014-04-01

59

Photocatalytic ozonation of dyes using copper ferrite nanoparticle prepared by co-precipitation method  

Microsoft Academic Search

In this paper, photocatalytic ozonation of dyes with copper ferrite (CuFe2O4) nanoparticle (CF nanoparticle) prepared by co-precipitation method was investigated. Reactive Red 198 (RR198) and Reactive Red 120 (RR120) were used as dye models. The characteristics of CF nanoparticle were studied using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). UV–Vis and ion chromatography (IC) analyses were employed to

Niyaz Mohammad Mahmoodi

2011-01-01

60

A new synthesis route from spent sulfuric acid pickling solution to ferrite nanoparticles  

Microsoft Academic Search

This paper describes a new synthesis route to magnetic ferrite nanoparticles, in which the dissolved ferrous iron(II) in spent pickling solutions is used as a starting material for the ferrite preparation. Firstly, the iron(II) in the spent pickling solution was microbially oxidized to iron(III) by using the acidophilic thermophilic microbe Acidianus brierleyi. Secondly, the iron(III) in the oxidized pickling solution

Yasuhiro Konishi; Toshiyuki Nomura; Kazunari Mizoe

2004-01-01

61

Biodistribution and acute toxicity of a nanofluid containing manganese iron oxide nanoparticles produced by a mechanochemical process.  

PubMed

Superparamagnetic iron oxide nanoparticles are candidate contrast agents for magnetic resonance imaging and targeted drug delivery. Biodistribution and toxicity assessment are critical for the development of nanoparticle-based drugs, because of nanoparticle-enhanced biological reactivity. Here, we investigated the uptake, in vivo biodistribution, and in vitro and in vivo potential toxicity of manganese ferrite (MnFe2O4) nanoparticles, synthesized by an original high-yield, low-cost mechanochemical process. Cultures of murine Balb/3T3 fibroblasts were exposed for 24, 48, or 72 hours to increasing ferrofluid concentrations. Nanoparticle cellular uptake was assessed by flow-cytometry scatter-light measurements and microscopy imaging after Prussian blue staining; cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony-forming assays. After a single intravenous injection, in vivo nanoparticle biodistribution and clearance were evaluated in mice by Mn spectrophotometric determination and Prussian blue staining in the liver, kidneys, spleen, and brain at different posttreatment times up to 21 days. The same organs were analyzed for any possible histopathological change. The in vitro study demonstrated dose-dependent nanoparticle uptake and statistically significant cytotoxic effects from a concentration of 50 ?g/mL for the MTT assay and 20 ?g/mL for the colony-forming assay. Significant increases in Mn concentrations were detected in all analyzed organs, peaking at 6 hours after injection and then gradually declining. Clearance appeared complete at 7 days in the kidneys, spleen, and brain, whereas in the liver Mn levels remained statistically higher than in vehicle-treated mice up to 3 weeks postinjection. No evidence of irreversible histopathological damage to any of the tested organs was observed. A comparison of the lowest in vitro toxic concentration with the intravenously injected dose and the administered dose of other ferrofluid drugs currently in clinical practice suggests that there might be sufficient safety margins for further development of our formulation. PMID:24790434

Bellusci, Mariangela; La Barbera, Aurelio; Padella, Franco; Mancuso, Mariateresa; Pasquo, Alessandra; Grollino, Maria Giuseppa; Leter, Giorgio; Nardi, Elisa; Cremisini, Carlo; Giardullo, Paola; Pacchierotti, Francesca

2014-01-01

62

Biodistribution and acute toxicity of a nanofluid containing manganese iron oxide nanoparticles produced by a mechanochemical process  

PubMed Central

Superparamagnetic iron oxide nanoparticles are candidate contrast agents for magnetic resonance imaging and targeted drug delivery. Biodistribution and toxicity assessment are critical for the development of nanoparticle-based drugs, because of nanoparticle-enhanced biological reactivity. Here, we investigated the uptake, in vivo biodistribution, and in vitro and in vivo potential toxicity of manganese ferrite (MnFe2O4) nanoparticles, synthesized by an original high-yield, low-cost mechanochemical process. Cultures of murine Balb/3T3 fibroblasts were exposed for 24, 48, or 72 hours to increasing ferrofluid concentrations. Nanoparticle cellular uptake was assessed by flow-cytometry scatter-light measurements and microscopy imaging after Prussian blue staining; cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony-forming assays. After a single intravenous injection, in vivo nanoparticle biodistribution and clearance were evaluated in mice by Mn spectrophotometric determination and Prussian blue staining in the liver, kidneys, spleen, and brain at different posttreatment times up to 21 days. The same organs were analyzed for any possible histopathological change. The in vitro study demonstrated dose-dependent nanoparticle uptake and statistically significant cytotoxic effects from a concentration of 50 ?g/mL for the MTT assay and 20 ?g/mL for the colony-forming assay. Significant increases in Mn concentrations were detected in all analyzed organs, peaking at 6 hours after injection and then gradually declining. Clearance appeared complete at 7 days in the kidneys, spleen, and brain, whereas in the liver Mn levels remained statistically higher than in vehicle-treated mice up to 3 weeks postinjection. No evidence of irreversible histopathological damage to any of the tested organs was observed. A comparison of the lowest in vitro toxic concentration with the intravenously injected dose and the administered dose of other ferrofluid drugs currently in clinical practice suggests that there might be sufficient safety margins for further development of our formulation.

Bellusci, Mariangela; La Barbera, Aurelio; Padella, Franco; Mancuso, Mariateresa; Pasquo, Alessandra; Grollino, Maria Giuseppa; Leter, Giorgio; Nardi, Elisa; Cremisini, Carlo; Giardullo, Paola; Pacchierotti, Francesca

2014-01-01

63

Synthesis of shape controlled ferrite nanoparticles by sonochemical technique.  

PubMed

Synthesis of magnetic iron oxides/ferrites in the nano scale by sonochemical synthesis has become prominent recently. This technique facilitates the synthesis of magnetic particles in the nano scale attributed to the hotspot mechanism arising due to acoustic cavitation induced chemical reaction. Generally volatile organometallic precursor compounds favoring the formation of fully amorphous particles have been used to synthesize various nano magnetic materials. We report here the synthesis of ultrafine, < 10 nm magnetic iron oxide nanoparticles by sonochemical technique starting with a non-volatile precursor iron salt such as iron citrate which seems to favor the formation of semi crystalline/crystalline particles as the reaction takes place either in the interfacial region or in the bulk solution. Mono dispersed, ultra fine, approximately 4 nm spherical shaped magnetic maghemite particles having a saturation magnetization of 58.2 emu/g and coercivity of 118 Oe were obtained at low values of pH, 10 while higher pH, 11-13 favored the formation of elongated, cylindrical, acicular particles with a reduced magnetization. The coercivity was also found to decrease with increasing pH, with it being 118 Oe at pH 10 and 3 Oe at pH 13. When the ultrasound amplitude/intensity was low, 38% heat treatment of the samples at 300 degrees C (at pH 10) was required to make them crystalline, while application of high intensity ultrasound, 50% amplitude served as a single step mechanism for obtaining crystalline maghemite particles. The maghemite particles obtained at a pH of 10 could find applications in information storage media. PMID:19049216

Theerdhala, Sriharsha; Alhat, Devendra; Vitta, Satish; Bahadur, D

2008-08-01

64

Induction of apoptosis in cancer cells by NiZn ferrite nanoparticles through mitochondrial cytochrome C release  

PubMed Central

The long-term objective of the present study was to determine the ability of NiZn ferrite nanoparticles to kill cancer cells. NiZn ferrite nanoparticle suspensions were found to have an average hydrodynamic diameter, polydispersity index, and zeta potential of 254.2 ± 29.8 nm, 0.524 ± 0.013, and ?60 ± 14 mV, respectively. We showed that NiZn ferrite nanoparticles had selective toxicity towards MCF-7, HepG2, and HT29 cells, with a lesser effect on normal MCF 10A cells. The quantity of Bcl-2, Bax, p53, and cytochrome C in the cell lines mentioned above was determined by colorimetric methods in order to clarify the mechanism of action of NiZn ferrite nanoparticles in the killing of cancer cells. Our results indicate that NiZn ferrite nanoparticles promote apoptosis in cancer cells via caspase-3 and caspase-9, downregulation of Bcl-2, and upregulation of Bax and p53, with cytochrome C translocation. There was a concomitant collapse of the mitochondrial membrane potential in these cancer cells when treated with NiZn ferrite nanoparticles. This study shows that NiZn ferrite nanoparticles induce glutathione depletion in cancer cells, which results in increased production of reactive oxygen species and eventually, death of cancer cells.

Al-Qubaisi, Mothanna Sadiq; Rasedee, Abdullah; Flaifel, Moayad Husein; Ahmad, Sahrim Hj; Hussein-Al-Ali, Samer; Hussein, Mohd Zobir; Zainal, Zulkarnain; Alhassan, Fatah H; Taufiq-Yap, Yun H; Eid, Eltayeb EM; Arbab, Ismail Adam; Al-Asbahi, Bandar A; Webster, Thomas J; Zowalaty, Mohamed Ezzat El

2013-01-01

65

Synthesis of NiCuZn ferrite nanoparticles and microwave absorption characterization  

Microsoft Academic Search

This study aimed at the low temperature synthesis of NixCu0.5?xZn0.5Fe2O4 ferrite nanoparticles using the citrate precursor method and the reflectivity characterization of Radar absorbing materials. The NiCuZn phase obtained at 350°C by the Rietveld method showed homogeneous nanoparticle formation. The analysis of particle size and the critical diameter of the domains indicated monodomain formation on nanometric scale. Vibrating sample magnetometry

U. R. Lima; M. C. Nasar; R. S. Nasar; M. C. Rezende; J. H. Araújo; J. F. Oliveira

2008-01-01

66

Abrasion and deformed layer formation of manganese-zinc ferrite in sliding contact with lapping tapes  

NASA Technical Reports Server (NTRS)

Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and the deformed layers produced in single-crystal Mn-Zn ferrite simulated heads during contact with lapping tapes. The crystaline state of the head is changed drastically during the abrasion process. Crystalline states ranging from nearly amorphous to highly textured polycrystalline can be produced on the wear surface of a single-crystal Mn-Zn ferrite head. The total thickness of the deformed layer was approximately 0.8 microns. This thickness increased as the load and abrasive grit size increased. The anisotropic wear of the ferrite was found to be inversely proportional to the hardness of the wear surface. The wear was lower in the order 211 111 10 0110. The wear of the ferrite increased markedly with an increase in sliding velocity and abrasive grit size.

Miyoshi, K.; Buckley, D. H.; Tanaka, K.

1986-01-01

67

Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel  

PubMed Central

Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network.

van Berkum, Susanne; Dee, Joris T.; Philipse, Albert P.; Erne, Ben H.

2013-01-01

68

Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel.  

PubMed

Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

van Berkum, Susanne; Dee, Joris T; Philipse, Albert P; Erné, Ben H

2013-01-01

69

Manganese  

SciTech Connect

Manganese (Mn) is a hard, brittle, gray-white transition metal, with the most numerous oxidation states of the elements in the first series of the Periodic Table. Since the manganese atom can donate up to seven electrons from its outer two shells, manganese compounds exist with valences from -3 to +7, the most common being +2, +4, and +7. Due to its sulfur-fixing, deoxidizing, and alloying properties, as well as its low cost, the principal commercial application for manganese is in iron and steel production. Manganese is also employed in non-ferrous metallurgy, batteries and chemical processes. Although potentially harmful to the respiratory and nervous systems, manganese is an essential element for animals and humans, and a micronutrient for plants.

Major-Sosias, M.A.

1996-10-01

70

Structure of Oxide Nanoparticles in Fe-16Cr MA/ODS Ferritic Steel  

SciTech Connect

Oxide nanoparticles in Fe-16Cr ODS ferritic steel fabricated by mechanical alloying (MA) method have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. A partial crystallization of oxide nanoparticles was frequently observed in as-fabricated ODS steel. The crystal structure of crystalline oxide particles is identified to be mainly Y{sub 4}Al{sub 2}O{sub 9} (YAM) with a monoclinic structure. Large nanoparticles with a diameter larger than 20 nm tend to be incoherent and have a nearly spherical shape, whereas small nanoparticles with a diameter smaller than 10 nm tend to be coherent or semi-coherent and have faceted boundaries. The oxide nanoparticles become fully crystallized after prolonged annealing at 900 C. These results lead us to propose a three-stage formation mechanism of oxide nanoparticles in MA/ODS steels.

Hsiung, L; Fluss, M; Kimura, A

2010-04-06

71

Maximizing hysteretic losses in magnetic ferrite nanoparticles via model-driven synthesis and materials optimization.  

PubMed

This article develops a set of design guidelines for maximizing heat dissipation characteristics of magnetic ferrite MFe2O4 (M = Mn, Fe, Co) nanoparticles in alternating magnetic fields. Using magnetic and structural nanoparticle characterization, we identify key synthetic parameters in the thermal decomposition of organometallic precursors that yield optimized magnetic nanoparticles over a wide range of sizes and compositions. The developed synthetic procedures allow for gram-scale production of magnetic nanoparticles stable in physiological buffer for several months. Our magnetic nanoparticles display some of the highest heat dissipation rates, which are in qualitative agreement with the trends predicted by a dynamic hysteresis model of coherent magnetization reversal in single domain magnetic particles. By combining physical simulations with robust scalable synthesis and materials characterization techniques, this work provides a pathway to a model-driven design of magnetic nanoparticles tailored to a variety of biomedical applications ranging from cancer hyperthermia to remote control of gene expression. PMID:24016039

Chen, Ritchie; Christiansen, Michael G; Anikeeva, Polina

2013-10-22

72

Moessbauer studies in zinc-manganese ferrites for use in measuring small velocities and accelerations with great precision  

NASA Technical Reports Server (NTRS)

Mossbauer spectroscopy was used for a systematic study of the magnetic behavior of manganese and zinc in mixed ferrites. It was observed that Zn2+ has preference to substitute Mn2+ at interstitial sites where the metal ions are tetrahedrally coordinated with four oxygen neighbors. The internal magnetic hyperfine field at the tetrahedral iron site is larger than that at the octahedral site. The relaxation effects were observed to play an important role as the zinc contents were increased, while the spin-correlation time and the magnetic field were observed to decrease in strength. It is concluded that Mossbauer effect data on complex materials, when used in conjunction with other data, can provide useful insight into the origin of the microscopic properties of magnetic materials.

Escue, W. T.; Gupta, R. G.; Mendiratta, R. G.

1975-01-01

73

Ni3Zn ferrite octahedral nanoparticles with high microwave permeability and high magnetic loss tangent  

NASA Astrophysics Data System (ADS)

Ni3Zn ferrite octahedral nanoparticles with grain size of about 40 nm were synthesized via a low temperature hydrothermal route. The saturation magnetization (Ms) and coercive force (Hc) of the sample are 57.5 emu/g and 197 Oe, respectively. In 50 MHz-8 GHz frequency range, the complex permeability and complex permittivity for Ni3Zn ferrite/wax composites containing 60 wt% ferrite powders were measured by a vector network analyzer. The real part ?r' of the permeability exhibits high values between 4 and 1.65 in 50 MHz-2 GHz range, and the imaginary part ?r'' of the permeability presents a broad peak with a maximum value of 1.53 at 2.1 GHz, the calculated reflection loss of ferrite/wax coating with the thickness of 8 mm reaches -13 dB at 2.1 GHz. The results indicate the as-prepared Ni3Zn ferrite octahedral nanoparticles can have applications in biomedicine, and microwave absorption and electric devices.

Wang, Zhongzhu; Wu, Mingzai; Jin, Shaowei; Li, Guang; Ma, Yongqing; Wang, Peihong

2013-10-01

74

Electron Spin Resonance Studies on the Quantum tunneling in Spinel Ferrite Nanoparticles  

NASA Astrophysics Data System (ADS)

The conversion of ferrimagnets to superparamagnets in spinel ferrite (MOFe2O3) nanoparticles from classical thermally driven transition becomes saliently from quantum tunneling on applying a transverse microwave magnetic field or by implicating of a strong internal anisotropic field at low temperatures. The microwave or crystal anisotropic field that is perpendicular to the Ising axis can destroy the magnetic long-range order as the field exceeds some critical values. Electron spin resonance (ESR) spectrometer, a very sensitive instrument with fast detecting window to explore quantum tunneling for magnetic nanoparticles, was exploited to study this fascinating interplay between thermal and quantum fluctuation in the vicinity of a quantum critical point. We have investigated the effects of various microwave fields and temperature dependence on the dynamic spin susceptibility of several kinds of spinel ferrite nanoparticles.

Hsieh, Chang-Tsun; Lue, Juh-Tzeng

2003-03-01

75

Study of Zn-Cu Ferrite Nanoparticles for LPG Sensing  

PubMed Central

Nanostructured zinc-copper mixed ferrite was synthesized using sol-gel method. XRD patterns of different compositions of zinc-copper ferrite, Zn(1?x)CuxFe2O4 (x = 0.0, 0.25, 0.50, 0.75), revealed single phase inverse spinel ferrite in all the samples synthesized. With increasing copper concentration, the crystallite size was found to be increased from 28?nm to 47?nm. The surface morphology of all the samples studied by the Scanning Electron Microscopy there exhibits porous structure of particles throughout the samples. The pellets of the samples are prepared for LPG sensing characteristics. The sensing is carried out at different operating temperatures (200, 225, and 250°C) with the variation of LPG concentrations (0.2, 0.4, and 0.6 vol%). The maximum sensitivity of 55.33% is observed at 250°C operating for the 0.6 vol% LPG.

Jain, Anuj; Baranwal, Ravi Kant; Bharti, Ajaya; Vakil, Z.; Prajapati, C. S.

2013-01-01

76

Cobalt ferrite nanoparticles: The control of the particle size and surface state and their effects on magnetic properties  

Microsoft Academic Search

In order to improve the efficacy of magnetic fluid hyperthermia (MFH) mediators, we synthesised cobalt ferrite nanoparticles with different sizes (between 5 and 7nm) via successive polyol synthesis. The static and dynamic magnetic properties of the prepared particles, dispersed in a solid matrix, were investigated in order to evaluate the possibility of applying cobalt ferrite as magnetic susceptors in MFH.

Giovanni Baldi; Daniele Bonacchi; Claudia Innocenti; Giada Lorenzi; Claudio Sangregorio

2007-01-01

77

Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

Mukherjee, A.; Banerjee, M.; Basu, S.; Pal, M.

2014-04-01

78

Manganese Nanoparticle Activates Mitochondrial Dependent Apoptotic Signaling and Autophagy in Dopaminergic Neuronal Cells  

PubMed Central

The production of man-made nanoparticles for various modern applications has increased exponentially in recent years, but the potential health effects of most nanoparticles are not well characterized. Unfortunately, in vitro nanoparticle toxicity studies are extremely limited by yet unresolved problems relating to dosimetry. In the present study, we systematically characterized manganese (Mn) nanoparticle sizes and examined the nanoparticle-induced oxidative signaling in dopaminergic neuronal cells. Differential interference contrast (DIC) microscopy and transmission electron microscopy (TEM) studies revealed that Mn nanoparticles range in size from single nanoparticles (~25 nM) to larger agglomerates when in treatment media. Manganese nanoparticles were effectively internalized in N27 dopaminergic neuronal cells, and they induced a time-dependent upregulation of the transporter protein transferrin. Exposure to 25–400 µg/mL Mn nanoparticles induced cell death in a time- and dose-dependent manner. Mn nanoparticles also significantly increased ROS, accompanied by a caspase-mediated proteolytic cleavage of proapoptotic protein kinase C? (PKC?), as well as activation loop phosphorylation. Blocking Mn nanoparticle-induced ROS failed to protect against the neurotoxic effects, suggesting the involvement of other pathways. Further mechanistic studies revealed changes in Beclin1 and LC3, indicating that Mn nanoparticles induce autophagy. Primary mesencephalic neuron exposure to Mn nanoparticles induced loss of TH positive dopaminergic neurons and neuronal processes. Collectively, our results suggest that Mn nanoparticles effectively enter dopaminergic neuronal cells and exert neurotoxic effects by activating an apoptotic signaling pathway and autophagy, emphasizing the need for assessing possible health risks associated with an increased use of Mn nanoparticles in modern applications.

Ngwa, Hilary Afeseh; Kanthasamy, Arthi; Gu, Yan; Fang, Ning; Anantharam, Vellareddy; Kanthasamy, Anumantha G.

2011-01-01

79

Synthesis and magnetic properties of cobalt ferrite (CoFe 2O 4) nanoparticles prepared by wet chemical route  

Microsoft Academic Search

Magnetic nanoparticles of cobalt ferrite have been synthesized by wet chemical method using stable ferric and cobalt salts with oleic acid as the surfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) confirmed the formation of single-phase cobalt ferrite nanoparticles in the range 15–48nm depending on the annealing temperature and time. The size of the particles increases with annealing temperature

K. Maaz; Arif Mumtaz; S. K. Hasanain; Abdullah Ceylan

2007-01-01

80

Synthesis and magnetic properties of CoFe2O4 spinel ferrite nanoparticles doped with lanthanide ions  

Microsoft Academic Search

Lanthanide ions have been doped into cobalt spinel ferrites using an oil-in-water micellar method to form CoLn0.12Fe1.88O4 nanoparticles with Ln=Ce, Sm, Eu, Gd, Dy, or Er. Doping with lanthanide ions (LnIII) modulates the magnetic properties of cobalt spinel ferrite nanoparticles. In particular cases of Gd3+ or Dy3+ ions, a dramatic increase in the blocking temperature and coercivity is observed. Indeed,

Myrtil L. Kahn; Z. John Zhang

2001-01-01

81

Effect of heat treatment on microwave absorption properties of Ni-Zn-Mg-La ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Spinel structure Ni-Zn-Mg-La ferrites have been prepared by the sol-gel route and investigated as a radar absorbing material (RAM) in a frequency range of 1-18 GHz. The structure and morphological studies on the nanoparticles of the ferrites have been carried out using X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The complex permeability and complex permittivity are measured by a network analyzer. The electromagnetic wave loss and microwave absorbing property are studied as a function of frequency, annealing temperature and thickness of the absorber. The results indicate that electromagnetic wave loss of the ferrite only annealed at 850 °C shows two peaks. The reflection loss varies with the change of the annealing temperature. The absorber annealed at 850 °C exhibits the best microwave absorbing properties, which is suitable for microwave absorption materials.

Liu, Yi; Wei, Shicheng; Xu, Binshi; Wang, Yujiang; Tian, Haoliang; Tong, Hui

2014-01-01

82

Manganese  

MedlinePLUS

... the body, including processing of cholesterol, carbohydrates, and protein. It might also be involved in bone formation. ... Antibiotics (Quinolone antibiotics)Manganese might decrease how much ... antibiotics might decrease the effectiveness of some antibiotics. To avoid ...

83

Comparison of surface effects in SiO2 coated and uncoated nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic properties of uncoated and silica coated nickel ferrite nanoparticles of comparable sizes have been studied in detail. Silica coated and uncoated nanoparticles were prepared by sol-gel and co-precipitation methods, respectively. Average crystallite size determined by X-ray diffraction is 12 nm and 14 nm for the silica coated and uncoated nanoparticles, respectively. Normalized saturation magnetization value of the coated nanoparticles was found to be lower than of uncoated nanoparticles, while a comparable small coercivity is observed for both the samples. Zero field cooled/field cooled (ZFC/FC) measurements reveal that the average blocking temperature (TB) of coated nanoparticles is lower than of the uncoated nanoparticles and is shifted to lower temperatures at high field. Thermoremanent magnetization (TRM) measurement indicates that the relaxation of coated nanoparticles have not been influenced very much with increasing cooling field as compared to uncoated nanoparticles and is attributed to enhanced surface effects in coated nanoparticles. The main source of enhanced surface effects in the coated nanoparticles is foremost disordered surface spins due to silica matrix. Temperature dependent AC susceptibility exhibits two peaks for the coated nanoparticles' sample. First peak corresponds to blocking of huge core spin while second peak at lower temperature is may be due to enhanced surface effects (spin-glass behavior). All these findings such as lower saturation magnetization, faster shift of blocking temperature at high field, small effect of high magnetic field on magnetic relaxation, low temperature out-of-phase AC susceptibility peak for the coated nanoparticles signify enhanced surface effects in them as compared to uncoated nanoparticles.

Nadeem, K.; Krenn, H.; Sarwar, W.; Mumtaz, M.

2014-01-01

84

Mössbauer spectroscopy, magnetic characteristics, and reflection loss analysis of nickel-strontium substituted cobalt ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

In current research work, Co1-xNix/2Srx/2Fe2O4 (x = 0-1 in a step of 0.2) ferrite nanoparticles were synthesized by a sol-gel method. According to the evolution in the subspectral areas obtained from Mössbauer spectroscopy, it was found that the relaxing iron belongs mostly to the site B, since the Mössbauer fraction of site A does not vary appreciably. With an increase in Ni-Sr substitution contents in cobalt ferrite, the coercivity and saturation of magnetization decrease. Variation of reflection loss versus frequency in microwave X-band demonstrates that the reflection peak shifts to lower frequency by adding substituted cations and the synthesized nanoparticles can be considered for application in electromagnetic wave absorber technology.

Ghasemi, Ali; Paesano, Andrea; Cerqueira Machado, Carla Fabiana; Shirsath, Sagar E.; Liu, Xiaoxi; Morisako, Akimitsu

2014-05-01

85

Thermodynamic modelling of the formation of zinc–manganese ferrite spinel in electric arc furnace dust  

Microsoft Academic Search

Electric arc furnace dust is generated when automobile scrap, containing galvanized steel, is remelted in an electric arc furnace. This dust is considered as a hazardous waste in most countries. Zinc is a major component of the dust and can be of significant commercial value. Typically, the majority of the zinc exists as zinc oxide (ZnO) and as a zinc–manganese

C. A. Pickles

2010-01-01

86

Manganese nanoparticle activates mitochondrial dependent apoptotic signaling and autophagy in dopaminergic neuronal cells  

SciTech Connect

The production of man-made nanoparticles for various modern applications has increased exponentially in recent years, but the potential health effects of most nanoparticles are not well characterized. Unfortunately, in vitro nanoparticle toxicity studies are extremely limited by yet unresolved problems relating to dosimetry. In the present study, we systematically characterized manganese (Mn) nanoparticle sizes and examined the nanoparticle-induced oxidative signaling in dopaminergic neuronal cells. Differential interference contrast (DIC) microscopy and transmission electron microscopy (TEM) studies revealed that Mn nanoparticles range in size from single nanoparticles ({approx} 25 nM) to larger agglomerates when in treatment media. Manganese nanoparticles were effectively internalized in N27 dopaminergic neuronal cells, and they induced a time-dependent upregulation of the transporter protein transferrin. Exposure to 25-400 {mu}g/mL Mn nanoparticles induced cell death in a time- and dose-dependent manner. Mn nanoparticles also significantly increased ROS, accompanied by a caspase-mediated proteolytic cleavage of proapoptotic protein kinase C{delta} (PKC{delta}), as well as activation loop phosphorylation. Blocking Mn nanoparticle-induced ROS failed to protect against the neurotoxic effects, suggesting the involvement of other pathways. Further mechanistic studies revealed changes in Beclin 1 and LC3, indicating that Mn nanoparticles induce autophagy. Primary mesencephalic neuron exposure to Mn nanoparticles induced loss of TH positive dopaminergic neurons and neuronal processes. Collectively, our results suggest that Mn nanoparticles effectively enter dopaminergic neuronal cells and exert neurotoxic effects by activating an apoptotic signaling pathway and autophagy, emphasizing the need for assessing possible health risks associated with an increased use of Mn nanoparticles in modern applications. -- Highlights: Black-Right-Pointing-Pointer Mn nanoparticles activate mitochondrial cell death signaling in dopaminergic neuron. Black-Right-Pointing-Pointer Mn nanoparticles activate caspase-mediated proteolytic cleavage of PKC{delta} cascade. Black-Right-Pointing-Pointer Mn nanoparticles induce autophagy in dopaminergic neuronal cells. Black-Right-Pointing-Pointer Mn nanoparticles induce loss of TH{sup +} neurons in primary mesencephalic cultures. Black-Right-Pointing-Pointer Study emphasizes neurotoxic risks of Mn nanoparticles to nigral dopaminergic system.

Afeseh Ngwa, Hilary; Kanthasamy, Arthi [Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, IA 50011 (United States)] [Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, IA 50011 (United States); Gu, Yan; Fang, Ning [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States)] [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Anantharam, Vellareddy [Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, IA 50011 (United States)] [Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, IA 50011 (United States); Kanthasamy, Anumantha G., E-mail: akanthas@iastate.edu [Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, IA 50011 (United States)

2011-11-15

87

Production of Co-Ti ferrite nanoparticles for use as agents in hyperthermia treatment  

Microsoft Academic Search

Co-Ti ferrite (Co1+xTixFe2-2xO4, 0.2 <= x <= 0.5) nanoparticles with average diameters ranging from 6 to 12 nm were produced by using our novel wet chemical method. The crystal structures and magnetic properties of the obtained samples were investigated by X-ray diffraction and superconducting quantum interference device (SQUID) magnetometer measurements. DC magnetization measurements showed that the coercive force Hc and

Daiki Shigeoka; Hikaru Katayanagi; Yuki Moro; Shinji Kimura; Toshiyuki Mashino; Yuko Ichiyanagi

2010-01-01

88

Finite size and surface effects on the magnetic properties of cobalt ferrite nanoparticles  

Microsoft Academic Search

Cobalt ferrite, CoFe2O4, nanoparticles in the size range 2–15 nm have been prepared using a non-aqueous solvothermal method. The magnetic studies\\u000a indicate a superparamagnetic behavior, showing an increase in the blocking temperatures (ranging from 215 to more than 340 K)\\u000a with the particle size, D\\u000a TEM. Fitting M versus H isotherms to the saturation approach law, the anisotropy constant, K, and the

C. Vázquez-Vázquez; M. A. López-Quintela; M. C. Buján-Núñez; J. Rivas

2011-01-01

89

Study of magnetic and structural properties of ferrofluids based on cobalt-zinc ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 30 nm, dispersed in a liquid carrier. Magnetic Co (1- x) Zn xFe 2O 4 ( x=0.25, 0.50, 0.75) ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through Energy Dispersive X-ray Spectroscopy and X-ray diffraction, respectively. Transmission Electron Microscopy (TEM) studies permitted determining nanoparticle size; grain size of nanoparticle conglomerates was established via Atomic Force Microscopy. The magnetic behavior of ferrofluids was characterized by Vibrating Sample Magnetometer (VSM); and finally, a magnetic force microscope was used to visualize the magnetic domains of Co (1- x) Zn xFe 2O 4 nanoparticles. X-ray diffraction patterns of Co (1- x) Zn xFe 2O 4 show the presence of the most intense peak corresponding to the (311) crystallographic orientation of the spinel phase of CoFe 2O 4. Fourier Transform Infrared Spectroscopy confirmed the presence of the bonds associated to the spinel structures; particularly for ferrites. The mean size of the crystallite of nanoparticles determined from the full-width at half maximum of the strongest reflection of the (311) peak by using the Scherrer approximation diminished from (9.5±0.3) nm to (5.4±0.2) nm when the Zn concentration increases from 0.21 to 0.75. The size of the Co-Zn ferrite nanoparticles obtained by TEM is in good agreement with the crystallite size calculated from X-ray diffraction patterns, using Scherer's formula. The magnetic properties investigated with the aid of a VSM at room temperature presented super-paramagnetic behavior, determined by the shape of the hysteresis loop. In this study, we established that the coercive field of Co (1- x) Zn xFe 2O 4 magnetic nanoparticles, the crystal and nanoparticle sizes determined by X-ray Diffraction and TEM, respectively, decrease with the increase of the Zn at%. Finally, our magnetic nanoparticles are not very hard magnetic materials given that the hysteresis loop is small and for this reason Co (1- x) Zn xFe 2O 4 nanoparticles are considered as soft magnetic material.

López, J.; González-Bahamón, L. F.; Prado, J.; Caicedo, J. C.; Zambrano, G.; Gómez, M. E.; Esteve, J.; Prieto, P.

2012-02-01

90

Facile solvothermal synthesis of mesoporous manganese ferrite (MnFe2O4) microspheres as anode materials for lithium-ion batteries.  

PubMed

We report the synthesis and characterization of the mesoporous manganese ferrite (MnFe2O4) microspheres as anode materials for Li-ion batteries. MnFe2O4 microspheres were synthesized by a facile solvothermal method using Mn(CH3COO)2 and FeCl3 as metal precursors in the presence of CH3COOK, CH3COOC2H5, and HOCH2CH2OH. The samples were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption, thermal gravimetric, X-ray photoelectron spectroscopy, temperature programmed reduction, and temperature programmed oxidation. The synthesized mesoporous MnFe2O4 microspheres composed of nanoparticles (10-30 nm) were 100-500 nm in diameter and had surface areas between 60.2 and 86.8 m(2) g(-1), depending on the CH3COOK amounts added in the preparation. After calcined at 600°C, MnFe2O4 was decomposed to Mn2O3 and Fe2O3 mixture. The mesoporous MnFe2O4 microspheres calcined at 400°C showed a capacity of 712.2 mA h g(-1) at 0.2C and 552.2 mA h g(-1) at 0.8C after 50 cycles, and an average capacity fading rate of around 0.28%/cycle and 0.48%/cycle, much better than those of the samples without calcination and calcined at 600°C. The work would be helpful in the fabrication of binary metal oxide anode materials for Li-ion batteries. PMID:23489612

Zhang, Zailei; Wang, Yanhong; Tan, Qiangqiang; Zhong, Ziyi; Su, Fabing

2013-05-15

91

Surface effects in the magnetic properties of crystalline 3 nm ferrite nanoparticles chemically synthesized  

NASA Astrophysics Data System (ADS)

We have systematically studied the magnetic properties of ferrite nanoparticles with 3, 7, and 11 nm of diameter with very narrow grain size distributions. Samples were prepared by the thermal decomposition of Fe(acac)3 in the presence of surfactants giving nanoparticles covered by oleic acid. High resolution transmission electron microscopy (HRTEM) images and XRD diffraction patterns confirms that all samples are composed by crystalline nanoparticles with the spinel structure expected for the iron ferrite. ac and dc magnetization measurements, as well in-field Mössbauer spectroscopy, indicate that the magnetic properties of nanoparticles with 11 and 7 nm are close to those expected for a monodomain, presenting large MS (close to the magnetite bulk). Despite the crystalline structure observed in HRTEM images, the nanoparticles with 3 nm are composed by a magnetically ordered region (core) and a surface region that presents a different magnetic order and it contains about 66% of Fe atoms. The high saturation and irreversibility fields in the M(H) loops of the particles with 3 nm together with the misalignment at 120 kOe in the in-field Mössbauer spectrum of surface component indicate a high surface anisotropy for the surface atoms, which is not observed for the core. For T<10 K, we observe an increase in the susceptibility and of the magnetization for former sample, indicating that surface moments tend to align with applied field increasing the magnetic core size.

Lima, E.; de Biasi, E.; Mansilla, M. Vasquez; Saleta, M. E.; Effenberg, F.; Rossi, L. M.; Cohen, R.; Rechenberg, H. R.; Zysler, R. D.

2010-11-01

92

Comparison effects and electron spin resonance studies of ?-Fe2O4 spinel type ferrite nanoparticles.  

PubMed

?-Fe2O4 spinel type ferrite nanoparticles have been synthesized by cetyltrimethylammonium bromide (CTAB) and ethylenediaminetetraacetic acid (EDTA) assisted hydrothermal route by using NaOH solution. Electron spin resonance (ESR/EPR) measurements of ?-Fe2O4 nanoparticles have been performed by a conventional x-band spectrometer at room temperature. The comparison effect of nanoparticles prepared by using CTAB and EDTA in different ?-doping on the structural and morphological properties have been investigated in detail. The effect of EDTA-assisted synthesis for ?-Fe2O4 nanoparticles are refined, and thus the spectroscopic g-factor are detected by using ESR signals. These samples can be considered as great benefits for magnetic recording media, electromagnetic and drug delivery applications. PMID:24858357

Bayrakdar, H; Yalç?n, O; Cengiz, U; Ozüm, S; Anigi, E; Topel, O

2014-11-11

93

Comparison effects and electron spin resonance studies of ?-Fe2O4 spinel type ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

?-Fe2O4 spinel type ferrite nanoparticles have been synthesized by cetyltrimethylammonium bromide (CTAB) and ethylenediaminetetraacetic acid (EDTA) assisted hydrothermal route by using NaOH solution. Electron spin resonance (ESR/EPR) measurements of ?-Fe2O4 nanoparticles have been performed by a conventional x-band spectrometer at room temperature. The comparison effect of nanoparticles prepared by using CTAB and EDTA in different ?-doping on the structural and morphological properties have been investigated in detail. The effect of EDTA-assisted synthesis for ?-Fe2O4 nanoparticles are refined, and thus the spectroscopic g-factor are detected by using ESR signals. These samples can be considered as great benefits for magnetic recording media, electromagnetic and drug delivery applications.

Bayrakdar, H.; Yalç?n, O.; Cengiz, U.; Özüm, S.; Anigi, E.; Topel, O.

2014-11-01

94

Influence of the morphology of ferrite nanoparticles on the directed assembly into magnetically anisotropic hierarchical structures.  

PubMed

The effect of the morphology of ferrite nanoparticles on their assembly in a magnetic field was studied. Thin BaFe12O19 nanoplatelets were compared with isotropic, spherical or octahedral, CoFe2O4 nanoparticles, all of which were synthesized hydrothermally. The nanoplatelets and nanoparticles assembled into a variety of hierarchical structures from stable suspensions during the "drop deposition" and drying in a magnetic field. The alignment of the nanoparticles in the magnetic field was observed in situ with an optical microscope. The morphologies of the nanoparticles and the subsequent assemblies were observed with transmission and scanning electron microscopes, respectively. The magnetic properties of the nanoparticles and the assemblies were measured with a vibrating-sample magnetometer. The BaFe12O19 nanoplatelets aligned in the plane of the substrate and formed several-micrometers-thick, ordered films with a magnetic alignment of approximately 90%. The CoFe2O4 nanoparticles assembled into thick, dense columns with a height of several hundreds of micrometers and showed a magnetic alignment of up to 60%. The differences in the morphologies and the magnetic alignments between the BaFe12O19 and CoFe2O4 hierarchical structures could be explained in terms of the differences in the shape and magnetocrystalline structure of the specific nanoparticles. PMID:24841592

Lisjak, Darja; Jenuš, Petra; Mertelj, Alenka

2014-06-10

95

Effects of magnetic cobalt ferrite nanoparticles on biological and artificial lipid membranes  

PubMed Central

Background The purpose of this work is to provide experimental evidence on the interactions of suspended nanoparticles with artificial or biological membranes and to assess the possibility of suspended nanoparticles interacting with the lipid component of biological membranes. Methods 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid vesicles and human red blood cells were incubated in suspensions of magnetic bare cobalt ferrite (CoFe2O4) or citric acid (CA)-adsorbed CoFe2O4 nanoparticles dispersed in phosphate-buffered saline and glucose solution. The stability of POPC giant unilamellar vesicles after incubation in the tested nanoparticle suspensions was assessed by phase-contrast light microscopy and analyzed with computer-aided imaging. Structural changes in the POPC multilamellar vesicles were assessed by small angle X-ray scattering, and the shape transformation of red blood cells after incubation in tested suspensions of nanoparticles was observed using scanning electron microscopy and sedimentation, agglutination, and hemolysis assays. Results Artificial lipid membranes were disturbed more by CA-adsorbed CoFe2O4 nanoparticle suspensions than by bare CoFe2O4 nanoparticle suspensions. CA-adsorbed CoFe2O4-CA nanoparticles caused more significant shape transformation in red blood cells than bare CoFe2O4 nanoparticles. Conclusion Consistent with their smaller sized agglomerates, CA-adsorbed CoFe2O4 nanoparticles demonstrate more pronounced effects on artificial and biological membranes. Larger agglomerates of nanoparticles were confirmed to be reactive against lipid membranes and thus not acceptable for use with red blood cells. This finding is significant with respect to the efficient and safe application of nanoparticles as medicinal agents.

Drasler, Barbara; Drobne, Damjana; Novak, Sara; Valant, Janez; Boljte, Sabina; Otrin, Lado; Rappolt, Michael; Sartori, Barbara; Iglic, Ales; Kralj-Iglic, Veronika; Sustar, Vid; Makovec, Darko; Gyergyek, Saso; Hocevar, Matej; Godec, Matjaz; Zupanc, Jernej

2014-01-01

96

Manganese-containing Prussian blue nanoparticles for imaging of pediatric brain tumors  

PubMed Central

Pediatric brain tumors (PBTs) are a leading cause of death in children. For an improved prognosis in patients with PBTs, there is a critical need to develop molecularly-specific imaging agents to monitor disease progression and response to treatment. In this paper, we describe manganese-containing Prussian blue nanoparticles as agents for molecular magnetic resonance imaging (MRI) and fluorescence-based imaging of PBTs. Our core-shell nanoparticles consist of a core lattice structure that incorporates and retains paramagnetic Mn2+ ions, and generates MRI contrast (both negative and positive). The biofunctionalized shell is comprised of fluorescent avidin, which serves the dual purpose of enabling fluorescence imaging and functioning as a platform for the attachment of biotinylated ligands that target PBTs. The surfaces of our nanoparticles are modified with biotinylated antibodies targeting neuron-glial antigen 2 or biotinylated transferrin. Both neuron-glial antigen 2 and the transferrin receptor are protein markers overexpressed in PBTs. We describe the synthesis, biofunctionalization, and characterization of these multimodal nanoparticles. Further, we demonstrate the MRI and fluorescence imaging capabilities of manganese-containing Prussian blue nanoparticles in vitro. Finally, we demonstrate the potential of these nanoparticles as PBT imaging agents by measuring their organ and brain biodistribution in an orthotopic mouse model of PBTs using ex vivo fluorescence imaging.

Dumont, Matthieu F; Yadavilli, Sridevi; Sze, Raymond W; Nazarian, Javad; Fernandes, Rohan

2014-01-01

97

Manganese-containing Prussian blue nanoparticles for imaging of pediatric brain tumors.  

PubMed

Pediatric brain tumors (PBTs) are a leading cause of death in children. For an improved prognosis in patients with PBTs, there is a critical need to develop molecularly-specific imaging agents to monitor disease progression and response to treatment. In this paper, we describe manganese-containing Prussian blue nanoparticles as agents for molecular magnetic resonance imaging (MRI) and fluorescence-based imaging of PBTs. Our core-shell nanoparticles consist of a core lattice structure that incorporates and retains paramagnetic Mn(2+) ions, and generates MRI contrast (both negative and positive). The biofunctionalized shell is comprised of fluorescent avidin, which serves the dual purpose of enabling fluorescence imaging and functioning as a platform for the attachment of biotinylated ligands that target PBTs. The surfaces of our nanoparticles are modified with biotinylated antibodies targeting neuron-glial antigen 2 or biotinylated transferrin. Both neuron-glial antigen 2 and the transferrin receptor are protein markers overexpressed in PBTs. We describe the synthesis, biofunctionalization, and characterization of these multimodal nanoparticles. Further, we demonstrate the MRI and fluorescence imaging capabilities of manganese-containing Prussian blue nanoparticles in vitro. Finally, we demonstrate the potential of these nanoparticles as PBT imaging agents by measuring their organ and brain biodistribution in an orthotopic mouse model of PBTs using ex vivo fluorescence imaging. PMID:24920896

Dumont, Matthieu F; Yadavilli, Sridevi; Sze, Raymond W; Nazarian, Javad; Fernandes, Rohan

2014-01-01

98

Highly aluminium doped barium and strontium ferrite nanoparticles prepared by citrate auto-combustion synthesis  

SciTech Connect

Aluminium doped barium and strontium hexaferrite nanoparticles BaAl {sub x}Fe{sub (12-x)}O{sub 19} and SrAl {sub x}Fe{sub (12-x)}O{sub 19} were synthesised via a sol-gel route using citric acid to complex the ions followed by an auto-combustion reaction. This method shows promise for the synthesis of complex ferrite powders with small particle size. It was found that around half of the iron could be substituted for aluminium in the barium ferrite with structure retention, whereas strontium aluminium ferrites could be produced with any aluminium content including total substitution of the iron. All synthesised materials consisted of particles smaller than 1 {mu}m, which is the size of a single magnetic domain, and various doping levels were achieved with the final elemental composition being within the bounds of experimental error. The materials show structural and morphological changes as they move from iron to aluminium ferrites. Such materials may be promising for imaging applications.

Shirtcliffe, Neil J. [Nottingham Trent University, Clifton Lane, Clifton, Nottingham NG11 8NS (United Kingdom)]. E-mail: neil.shirtcliffe@ntu.ac.uk; Thompson, Simon [Nottingham Trent University, Clifton Lane, Clifton, Nottingham NG11 8NS (United Kingdom); O'Keefe, Eoin S. [QinetiQ, Farnborough, Hampshire (United Kingdom); Appleton, Steve [QinetiQ, Farnborough, Hampshire (United Kingdom); Perry, Carole C. [Nottingham Trent University, Clifton Lane, Clifton, Nottingham NG11 8NS (United Kingdom)]. E-mail: carole.perry@ntu.ac.uk

2007-02-15

99

Recent advances in nanosized Mn-Zn ferrite magnetic fluid hyperthermia for cancer treatment.  

PubMed

This paper reviews the recent research and development of nanosized manganese zinc (Mn-Zn) ferrite magnetic fluid hyperthermia (MFH) for cancer treatment. Mn-Zn ferrite MFH, which has a targeted positioning function that only the temperature of tumor tissue with magnetic nanoparticles can rise, while normal tissue without magnetic nanoparticles is not subject to thermal damage, is a promising therapy for cancer. We introduce briefly the composition and properties of magnetic fluid, the concept of MFH, and features of Mn-Zn ferrite magnetic nanoparticles for MFH such as thermal bystander effect, universality, high specific absorption rate, the targeting effect of small size, uniformity of hyperthermia temperature, and automatic temperature control and constant temperature effect. Next, preparation methods of Mn-Zn ferrite magnetic fluid are discussed, and biocompatibility and biosecurity of Mn-Zn ferrite magnetic fluid are analyzed. Then the applications of nanosized Mn-Zn ferrite MFH in cancer are highlighted, including nanosized Mn-Zn ferrite MFH alone, nanosized Mn-Zn ferrite MFH combined with As2O3 chemotherapy, and nanosized Mn-Zn ferrite MFH combined with radiotherapy. Finally, the combination application of nanosized Mn-Zn ferrite MFH and gene-therapy is conceived, and the challenges and perspectives for the future of nanosized Mn-Zn ferrite MFH for oncotherapy are discussed. PMID:24730298

Lin, Mei; Huang, Junxing; Sha, Min

2014-01-01

100

Online monitoring of cell metabolism to assess the toxicity of nanoparticles: the case of cobalt ferrite.  

PubMed

Different in vitro assays are successfully used to determine the relative cytotoxicity of a broad range of compounds. Nevertheless, different research groups have pointed out the difficulty in using the same tests to assess the toxicity of nanoparticles (NPs). In this study, we evaluated the possible use of a microphysiometer, Bionas 2500 analyzing system Bionas GmbH®, to detect in real time changes in cell metabolisms linked to NPs exposure. We focused our work on response changes of fibroblast cultures linked to exposure by cobalt ferrite NPs and compared the results to conventional in vitro assays. The measurements with the microphysiometer showed a cobalt ferrite cytotoxic effect, confirmed by the Colony Forming Efficiency assay. In conclusion, this work demonstrated that the measurement of metabolic parameters with a microphysiometer is a promising method to assess the toxicity of NPs and offers the advantage to follow on-line the cell metabolic changes. PMID:21495878

Mariani, Valentina; Ponti, Jessica; Giudetti, Guido; Broggi, Francesca; Marmorato, Patrick; Gioria, Sabrina; Franchini, Fabio; Rauscher, Hubert; Rossi, François

2012-05-01

101

Magnetic and Mössbauer spectroscopic studies of NiZn ferrite nanoparticles synthesized by a combustion method  

NASA Astrophysics Data System (ADS)

The properties of nanocrystalline Ni0.5Zn0.5Fe2O4 synthesized by an auto-combustion method have been investigated by magnetic measurements and Mössbauer spectroscopy. The as-synthesized single phase nanosized ferrite powder is annealed at different temperatures in the range 673 1,273 K to obtain nanoparticles of different sizes. The powders are characterized by powder X-ray diffraction, vibrating sample magnetometer, transmission electron microscopy and Mössbauer spectroscopy. The as-synthesized powder with average particle size of ~9 nm is superparamagnetic. Magnetic transition temperature increases up to 665 K for the nanosized powder as compared to the transition temperature of 548 K for the bulk ferrite. This has been confirmed as due to the abnormal cation distribution, as evidenced from room temperature Mössbauer spectroscopic studies.

Sreeja, V.; Vijayanand, S.; Deka, S.; Joy, P. A.

2008-04-01

102

Influence of cobalt on structural and magnetic properties of nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Improving the magnetic response of nanocrystalline nickel ferrites is the key issue in high density recording media. A series of cobalt substituted nickel ferrite nanoparticles with composition Ni(1-x)CoxFe2O4, where 0.0 ? x ? 1.0, are synthesized using co-precipitation method. The XRD spectra revealed the single phase spinel structure and the average sizes of nanoparticles are estimated to be 16-19 nm. These sizes are small enough to achieve the suitable signal to noise ratio in the high density recording media. The lattice parameter and coercivity shows monotonic increment with the increase of Co contents ascribed to the larger ionic radii of the cobalt ion. The specific saturation magnetization (Ms), remanent magnetization (Mr) and the coercivity (Hc) of the spinel ferrites are further improved by the substitutions of Co+2 ions. The values of Ms for NiFe2O4 and CoFe2O4 are found to be 43.92 and 78.59 emu/g, respectively and Hc are in the range of 51-778 Oe. The FTIR spectra of the spinel phase calcinated at 600 °C exhibit two prominent fundamental absorption bands in the range of 350-600 cm-1 assigned to the intrinsic stretching vibrations of the metal at the tetrahedral and octahedral sites. The role played by the Co ions in improving the structural and magnetic properties are analyzed and understood. Our simple, economic and environmental friendly preparation method may contribute towards the controlled growth of high quality ferrite nanopowders, potential candidates for recording.

Ati, Ali A.; Othaman, Zulkafli; Samavati, Alireza

2013-11-01

103

HRTEM Study of Oxide Nanoparticles in K3-ODS Ferritic Steel Developed for Radiation Tolerance  

SciTech Connect

Crystal and interfacial structures of oxide nanoparticles and radiation damage in 16Cr-4.5Al-0.3Ti-2W-0.37 Y{sub 2}O{sub 3} ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y{sub 4}Al{sub 2}O{sub 9} (YAM) oxide compound. Orientation relationships between the oxide and the matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles and multiple crystalline domains formed within a nanoparticle lead us to propose a three-stage mechanism to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels. Effects of nanoparticle size and density on cavity formation induced by (Fe{sup 8+} + He{sup +}) dual-beam irradiation are briefly addressed.

Hsiung, L; Fluss, M; Tumey, S; Kuntz, J; El-Dasher, B; Wall, M; Choi, W; Kimura, A; Willaime, F; Serruys, Y

2009-11-02

104

Influence of spherical assembly of copper ferrite nanoparticles on magnetic properties: orientation of magnetic easy axis.  

PubMed

The magnetic properties of copper ferrite (CuFe2O4) nanoparticles prepared via sol-gel auto combustion and facile solvothermal method are studied focusing on the effect of nanoparticle arrangement. Randomly oriented CuFe2O4 nanoparticles (NP) are obtained from the sol-gel auto combustion method, while the solvothermal method allows us to prepare iso-oriented uniform spherical ensembles of CuFe2O4 nanoparticles (NS). X-ray diffractometry (XRD), atomic absorption spectroscopy (AAS), infra-red (IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), (57)Fe Mössbauer spectroscopy and vibrating sample magnetometer (VSM) are used to investigate the composition, microstructure and magnetic properties of as-prepared ferrite nanoparticles. The field-dependent magnetization measurement for the NS sample at low temperature exhibits a step-like rectangular hysteresis loop (MR/MS? 1), suggesting cubic anisotropy in the system, whereas for the NP sample, typical features of uniaxial anisotropy (MR/MS? 0.5) are observed. The coercive field (HC) for the NS sample shows anomalous temperature dependence, which is correlated with the variation of effective anisotropy (KE) of the system. A high-temperature enhancement of HC and KE for the NS sample coincides with a strong spin-orbit coupling in the sample as evidenced by significant modification of Cu/Fe-O bond distances. The spherical arrangement of nanocrystals at mesoscopic scale provokes a high degree of alignment of the magnetic easy axis along the applied field leading to a step-like rectangular hysteresis loop. A detailed study on the temperature dependence of magnetic anisotropy of the system is carried out, emphasizing the influence of the formation of spherical iso-oriented assemblies. PMID:24714977

Chatterjee, Biplab K; Bhattacharjee, Kaustav; Dey, Abhishek; Ghosh, Chandan K; Chattopadhyay, Kalyan K

2014-06-01

105

Microwave absorption properties of conducting polymer composite with barium ferrite nanoparticles in 12.4-18 GHz  

NASA Astrophysics Data System (ADS)

Conducting polymer nanocomposites of polyphenyl amine with barium ferrite nanoparticles (50-70 nm) have been synthesized via emulsion polymerization. The complex permittivity, permeability, and microwave absorption properties of the composite were studied in the 12.4-18 GHz (Ku band) frequency range. The composite has shown high shielding effectiveness due to absorption (SEA) of 28.9 dB (~99.9%), which strongly depends on dielectric loss, magnetic permeability, and volume fraction of barium ferrite nanoparticles. The high value of SEA suggests that these composites can be used as a promising radar absorbing materials.

Ohlan, Anil; Singh, Kuldeep; Chandra, Amita; Dhawan, S. K.

2008-08-01

106

Faraday rotation of cobalt ferrite nanoparticle polymer composite films at cryogenic temperatures.  

PubMed

This paper investigates the behavior of the Verdet constant for cobalt ferrite (CoFe2O4) nanoparticles polymer composite films at low temperatures using a 532 nm laser source. An experimental setup for Faraday rotation (FR) at low temperatures is introduced and FRs were measured at various temperatures. Verdet constants were deduced from the paramagnetic model for terbium gallium garnet glass where ?4× improvement was observed at 40° K for CoFe2O4 composite film. PMID:24787165

Demir, Veysi; Gangopadhyay, Palash; Norwood, Robert A; Peyghambarian, Nasser

2014-04-01

107

Effect of samarium substitution on structural and magnetic properties of magnesium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Samarium doped magnesium ferrite was prepared (MgSmxFe2-xO4) by sol-gel method. X-ray diffraction analysis reveals that the samples are single phasic with crystallite sizes in the 13-25 nm regime. Increase in lattice parameter with doping concentration suggests the expansion in unit cell with Sm3+ doping. Fourier Transform Infrared Spectrum shows substitution of Sm3+ ions in octahedral B site. Transmission Electron Micrograph shows the spherical shape of nano-particles. Magnetic measurement shows a decrease in magnetization with doping which is explained using dependence on particle size.

Thankachan, Smitha; Jacob, Binu P.; Xavier, Sheena; Mohammed, E. M.

2013-12-01

108

Electromagnetic properties of NiZn ferrite nanoparticles and their polymer composites  

NASA Astrophysics Data System (ADS)

The magnetic properties of polycrystalline NiZn ferrite nanoparticles synthesized using a polyol-reduction and coprecipitation reaction methods have been investigated. The effects on magnetization of synthesis approach, chemical composition, processing conditions, and on the size of nanoparticles on magnetization have been investigated. The measured room-temperature magnetization for the as-prepared magnetic nanoparticles (MNP) synthesized via polyol-reduction and coprecipitation is 69 Am2 kg-1 and 14 Am2 kg-1, respectively. X-ray diffraction measurements confirm spinel structure of the particles with an estimated grain size of ˜80 nm obtained from the polyol-reduction and 28 nm obtained from these coprecipitation techniques. Upon calcination under atmospheric conditions at different temperatures between 800 °C and 1000 °C, the magnetization, M, of the coprecipitated MNP increases to 76 Am2 kg-1 with an estimated grain size of 90 nm. The MNP-polymer nanocomposites made from the synthesized MNP in various loading fraction and high density polyethylene exhibit interesting electromagnetic properties. The measured permeability and permittivity of the magnetic nanoparticle-polymer nanocomposites increases with the loading fractions of the magnetic nanoparticles, suggesting control for impedance matching for antenna applications.

Parsons, P.; Duncan, K.; Giri, A. K.; Xiao, J. Q.; Karna, S. P.

2014-05-01

109

Cationic Distribution and Oxidation Mechanism of Trivalent Manganese Ions in Submicrometer Mn xCoFe 2- xO 4Spinel Ferrites  

NASA Astrophysics Data System (ADS)

Submicrometer Mn xCoFe 2- xO 4(0 ? x< 1) spinel particles with a spherical shape were prepared at low temperature from oxalic precursors. Because of their small crystallite size (about 50 nm), these ferrite particles can be oxidized below 400°C giving cubic deficient spinels having both Mn 3+and Mn 4+ions because of oxido-reduction phenomena. Information about the valence state of the manganese and cobalt ions and cation distribution between tetrahedral ( A) and octahedral ( B) sites are derived from lattice parameter variation, IR spectroscopy, thermogravimetric analysis, and electrical conductivity. A kinetics study of the oxidation of Mn 3+ions shows that oxidation proceeds by cation diffusion through a topotactic reaction with a constant chemical diffusion coefficient for x< 0.60 and variable above x= 0.80 and an activation energy close to 115 kJ mol -1but, however, depending on manganese substitution content.

Laarj, M.; Kacim, S.; Gillot, B.

1996-08-01

110

Study of the thermal stability of nanoparticle distributions in an oxide dispersion strengthened (ODS) ferritic alloys  

NASA Astrophysics Data System (ADS)

Oxide dispersion strengthened (ODS) ferritic alloys have a vast applicability due to their excellent mechanical resistance at high temperature. The precipitate dispersion of the nanoparticles in the matrix has a great effect on the creep properties of the material; in order to study the kinetics of precipitation of Y2Ti2O7 nanoparticles in Fe-14Cr1W ODS alloy, annealing experiments were taken at different temperatures (1050 °C-1400 °C) and for different times (0.5-10 h), then these samples were characterized by the small-angle neutron scattering technique (SANS) under magnetic field and TEM investigations and microhardness measurements were performed to gather nanoscopic information about the dispersed oxide particles size.

Zhong, S. Y.; Ribis, J.; Klosek, V.; de Carlan, Y.; Lochet, N.; Ji, V.; Mathon, M. H.

2012-09-01

111

Synthesis and optical properties of nickel zinc ferrite nanoparticles grown within mesoporous silica template  

NASA Astrophysics Data System (ADS)

Nanocomposite (NC) of nickel zinc ferrite (NZF) in mesoporous silica template (KIT-6) was synthesized and characterized in this work. Impregnation procedure was used to synthesize NZF nanoparticles within the pores of KIT-6. The samples were characterized by transmission electron microscopy (TEM), FTIR and UV-Vis absorption studies and room temperature (RT) photoluminescence (PL) measurement. The morphology from Transmission Electron Microscopy of the NC showed the ordered porous structure of KIT-6 remained undistorted even after the incorporation of NZF nanoparticles within its pores. From UV-Vis spectra of the NC, a blue shift in the absorption band due to quantum confinement effect was found. Due to some defects present a broad PL peak centred at 490 nm after excitation at 428 nm of the NC was observed.

Banerjee, Shilpi; Chakravorty, Dipankar

2012-06-01

112

Folate conjugated carboxymethyl chitosan–manganese doped zinc sulphide nanoparticles for targeted drug delivery and imaging of cancer cells  

Microsoft Academic Search

We developed a novel folic acid (FA) conjugated carboxymethyl chitosan coordinated to manganese doped zinc sulphide quantum dot (FA–CMC–ZnS:Mn) nanoparticles. The system can be used for targeting, controlled drug delivery and also imaging of cancer cells. The prepared nanoparticles were characterized using SEM, AFM, FT-IR, UV and DLS studies. The size range of 5-FU encapsulated FA–CMC–ZnS:Mn nanoparticles were from 130

Manjusha Elizabeth Mathew; Jithin C. Mohan; K. Manzoor; S. V. Nair; H. Tamura; R. Jayakumar

2010-01-01

113

Influence of ferrite nanoparticle type and content on the crystallization kinetics and electroactive phase nucleation of poly(vinylidene fluoride).  

PubMed

This work reports on the nucleation of the ?-phase of poly(vinylidene fluoride) (PVDF) by incorporating CoFe(2)O(4) and NiFe(2)O(4) nanoparticles, leading in this way to the preparation of magnetoelectric composites. The fraction of filler nanoparticles needed to produce the same ?- to ?-phase ratio in crystallized PVDF is 1 order of magnitude lower in the cobalt ferrite nanoparticles. The interaction between nanoparticles and PVDF chains induce the all-trans conformation in PVDF segments, and this structure then propagates in crystal growth. The nucleation kinetics is enhanced by the presence of nanoparticles, as corroborated by the increasing number of spherulites with increasing nanoparticle content and by the variations of the Avrami's exponent. Further, the decrease of the crystalline fraction of PVDF with increasing nanoparticle content indicates that an important fraction of polymer chains are confined in interphases with the filler particle. PMID:21545124

Sencadas, Vitor; Martins, Pedro; Pitães, Alexandre; Benelmekki, Maria; Gómez Ribelles, José Luis; Lanceros-Mendez, Senentxu

2011-06-01

114

Enhanced antibactericidal function of W 4+-doped titania-coated nickel ferrite composite nanoparticles: A biomaterial system  

Microsoft Academic Search

The study demonstrates a distinct enhancement of antimicrobial activity of W4+-doped titania that is coated on nickel ferrite nanoparticles in comparison to undoped titania. The composite nanoparticles were synthesized by uniquely combining reverse micelle and chemical hydrolysis synthesis methods [Rana S, Rawat J, Misra RDK, Acta Biomater 2005;1:691]. The superior antimicrobial activity of W4+-doped titania is related to the inhibition

B. K. Sunkara; R. D. K. Misra

2008-01-01

115

Formation of octapod MnO nanoparticles with enhanced magnetic properties through kinetically-controlled thermal decomposition of polynuclear manganese complexes.  

PubMed

Polynuclear manganese complexes are used as precursors for the synthesis of manganese oxide nanoparticles (MnO NPs). Altering the thermal decomposition conditions can shift the nanoparticle product from spherical, thermodynamically-driven NPs to unusual, kinetically-controlled octapod structures. The resulting increased surface area profoundly alters the NP's surface-dependent magnetism and may have applications in nanomedicine. PMID:24220037

Douglas, Fraser J; MacLaren, Donald A; Tuna, Floriana; Holmes, William M; Berry, Catherine C; Murrie, Mark

2014-01-01

116

Magnetic properties of cobalt-ferrite nanoparticles embedded in polystyrene resin  

NASA Astrophysics Data System (ADS)

Samples of maghemite and cobalt-ferrite nanoparticles (sizes, 3-10 nm) were prepared by cross-linking sulfonated polystyrene resin with aqueous solutions of (1) FeCl2, (2) 80%FeCl2+20%CoCl2, (3) FeCl3, and (4) 80%FeCl3+20%CoCl2 by volume. Chemical analysis, x-ray powder-diffraction, and 57Fe Mössbauer spectroscopic measurements show that samples 1 and 3 consist of ?-Fe2O3 nanoparticles (sizes, ~10 and 3 nm) and sample 2 and 4 consist of CoxFe3-xO4 nanoparticles (sizes, ~10 and 4 nm). The temperature dependence of the zero-field-cooled and field-cooled magnetizations at low temperatures, together with a magnetic hysteresis in the M versus H data below blocking temperatures, demonstrate superparamagnetic behavior. The introduction of Co in the iron oxide-resin matrix results in an increase in the blocking temperature of nanoparticles.

Vaishnava, P. P.; Senaratne, U.; Buc, E.; Naik, R.; Naik, V. M.; Tsoi, G.; Wenger, L. E.; Boolchand, P.

2006-04-01

117

Microstructural and Mössbauer properties of low temperature synthesized Ni-Cd-Al ferrite nanoparticles.  

PubMed

We report the influence of Al3+ doping on the microstructural and Mössbauer properties of ferrite nanoparticles of basic composition Ni0.2Cd0.3Fe2.5 - xAlxO4 (0.0 ? x ? 0.5) prepared through simple sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, transmission electron microscopy (TEM), Fourier transformation infrared (FTIR), and Mössbauer spectroscopy techniques were used to investigate the structural, chemical, and Mössbauer properties of the grown nanoparticles. XRD results confirm that all the samples are single-phase cubic spinel in structure excluding the presence of any secondary phase corresponding to any structure. SEM micrographs show the synthesized nanoparticles are agglomerated but spherical in shape. The average crystallite size of the grown nanoparticles was calculated through Scherrer formula and confirmed by TEM and was found between 2 and 8 nm (± 1). FTIR results show the presence of two vibrational bands corresponding to tetrahedral and octahedral sites. Mössbauer spectroscopy shows that all the samples exhibit superparamagnetism, and the quadrupole interaction increases with the substitution of Al3+ ions. PMID:21851597

Batoo, Khalid Mujasam

2011-01-01

118

Magnetic properties of cobalt-ferrite nanoparticles embedded in polystyrene resin  

SciTech Connect

Samples of maghemite and cobalt-ferrite nanoparticles (sizes, 3-10 nm) were prepared by cross-linking sulfonated polystyrene resin with aqueous solutions of (1) FeCl{sub 2}, (2) 80%FeCl{sub 2}+20%CoCl{sub 2}, (3) FeCl{sub 3}, and (4) 80%FeCl{sub 3}+20%CoCl{sub 2} by volume. Chemical analysis, x-ray powder-diffraction, and {sup 57}Fe Moessbauer spectroscopic measurements show that samples 1 and 3 consist of {gamma}-Fe{sub 2}O{sub 3} nanoparticles (sizes, {approx}10 and 3 nm) and sample 2 and 4 consist of Co{sub x}Fe{sub 3-x}O{sub 4} nanoparticles (sizes, {approx}10 and 4 nm). The temperature dependence of the zero-field-cooled and field-cooled magnetizations at low temperatures, together with a magnetic hysteresis in the M versus H data below blocking temperatures, demonstrate superparamagnetic behavior. The introduction of Co in the iron oxide-resin matrix results in an increase in the blocking temperature of nanoparticles.

Vaishnava, P. P.; Senaratne, U.; Buc, E.; Naik, R.; Naik, V. M.; Tsoi, G.; Wenger, L. E.; Boolchand, P. [Kettering University, Flint, Michigan 48504 (United States); Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201 (United States); University of Michigan-Dearborn, Dearborn, Michigan 48128 (United States); University of Alabama, Birmingham, Alabama 35294 (United States); Department of ECECS, University of Cincinnati, Ohio 45221 (United States)

2006-04-15

119

Microstructural and M?ssbauer properties of low temperature synthesized Ni-Cd-Al ferrite nanoparticles  

PubMed Central

We report the influence of Al3+ doping on the microstructural and Mössbauer properties of ferrite nanoparticles of basic composition Ni0.2Cd0.3Fe2.5 - xAlxO4 (0.0 ? x ? 0.5) prepared through simple sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, transmission electron microscopy (TEM), Fourier transformation infrared (FTIR), and Mössbauer spectroscopy techniques were used to investigate the structural, chemical, and Mössbauer properties of the grown nanoparticles. XRD results confirm that all the samples are single-phase cubic spinel in structure excluding the presence of any secondary phase corresponding to any structure. SEM micrographs show the synthesized nanoparticles are agglomerated but spherical in shape. The average crystallite size of the grown nanoparticles was calculated through Scherrer formula and confirmed by TEM and was found between 2 and 8 nm (± 1). FTIR results show the presence of two vibrational bands corresponding to tetrahedral and octahedral sites. Mössbauer spectroscopy shows that all the samples exhibit superparamagnetism, and the quadrupole interaction increases with the substitution of Al3+ ions.

2011-01-01

120

Synthesis of lithium manganese phosphate nanoparticle and its properties  

NASA Astrophysics Data System (ADS)

The LiMnPO4 fine particles were synthesized by polyol method. To optimize the synthesis conditions of the LiMnPO4 compounds, we have prepared the LiMnPO4 compound with different processing conditions. The samples were characterized by X-ray diffraction, scanning electron microscope observation and infrared spectroscope study. The particle size of the as-prepared samples are very small than the sample calcined at 500C for 3 h in Ar. The electrochemical properties of the cathodes were studied by galvanostatic method. All the samples exhibit a sloping line of the voltage profile, which is the characteristic of the nanoparticles.

Kim, T. R.; Kim, D. H.; Ryu, H. W.; Moon, J. H.; Lee, J. H.; Boo, S.; Kim, J.

2007-05-01

121

Synthesis and magnetic properties of CoFe2O4 spinel ferrite nanoparticles doped with lanthanide ions  

NASA Astrophysics Data System (ADS)

Lanthanide ions have been doped into cobalt spinel ferrites using an oil-in-water micellar method to form CoLn0.12Fe1.88O4 nanoparticles with Ln=Ce, Sm, Eu, Gd, Dy, or Er. Doping with lanthanide ions (LnIII) modulates the magnetic properties of cobalt spinel ferrite nanoparticles. In particular cases of Gd3+ or Dy3+ ions, a dramatic increase in the blocking temperature and coercivity is observed. Indeed, the introduction of only 4% of Gd3+ ions increases the blocking temperature ~100 K and the coercivity 60%. Initial studies on the magnetic properties of these doped nanoparticles clearly demonstrate that the relationship between the modulation of magnetic properties and the nature of doped LnIII ions is interesting but very complex.

Kahn, Myrtil L.; Zhang, Z. John

2001-06-01

122

Synthesis and characterization of CoFe2O4 ferrite nanoparticles obtained by an electrochemical method.  

PubMed

Uniform size cobalt ferrite nanoparticles have been synthesized in one step using an electrochemical technique. Synthesis parameters such as the current density, temperature and stirring were optimized to produce pure cobalt ferrite. The nanoparticles have been investigated by means of magnetic measurements, Mössbauer spectroscopy, x-ray powder diffraction and transmission electron microscopy. The average size of the electrosynthesized samples was controlled by the synthesis parameters and this showed a rather narrow size distribution. The x-ray analysis shows that the CoFe(2)O(4) obtained presents a totally inverse spinel structure. The magnetic properties of the stoichiometric nanoparticles show ferromagnetic behavior at room temperature with a coercivity up to 6386 Oe and a saturation magnetization of 85 emu g(-1). PMID:22894928

Mazarío, E; Herrasti, P; Morales, M P; Menéndez, N

2012-09-01

123

Colorimetric detection of manganese(II) ions using gold/dopa nanoparticles.  

PubMed

We report here a one-pot, greener, eco-friendly strategy for the synthesis of gold nanoparticles using L-dopa. The as-prepared dopa-functionalized gold nanoparticles (AuNPs/dopa) can detect low concentrations of manganese(II) metal ions in aqueous solution. The binding forces between dopa and Mn(2+) ions cause dopa-functionalized gold nanoparticles to come closer together, decreasing the interparticle distance and aggregating it with a change in color of colloidal solution from red to purplish-blue. Dynamic light scattering (DLS) analysis showed a decreased surface charge on the surface of gold nanoparticles when exposed to Mn(2+) ions, which caused cross-linking aggregation. Transmission electron microscopic (TEM) images also revealed the aggregation of gold nanoparticles with the addition of Mn(2+) ions. The extinction ratio of absorbance at 700-550nm (A700/A550) was linear against the concentration of [Mn(2+)] ions. Thus, the optical absorption spectra of gold colloidal solution before and after the addition of Mn(2+) ions reveal the concentration of Mn(2+) ions in solution. PMID:24825666

Narayanan, Kannan Badri; Park, Hyun Ho

2014-10-15

124

Colorimetric detection of manganese(II) ions using gold/dopa nanoparticles  

NASA Astrophysics Data System (ADS)

We report here a one-pot, greener, eco-friendly strategy for the synthesis of gold nanoparticles using L-dopa. The as-prepared dopa-functionalized gold nanoparticles (AuNPs/dopa) can detect low concentrations of manganese(II) metal ions in aqueous solution. The binding forces between dopa and Mn2+ ions cause dopa-functionalized gold nanoparticles to come closer together, decreasing the interparticle distance and aggregating it with a change in color of colloidal solution from red to purplish-blue. Dynamic light scattering (DLS) analysis showed a decreased surface charge on the surface of gold nanoparticles when exposed to Mn2+ ions, which caused cross-linking aggregation. Transmission electron microscopic (TEM) images also revealed the aggregation of gold nanoparticles with the addition of Mn2+ ions. The extinction ratio of absorbance at 700-550 nm (A700/A550) was linear against the concentration of [Mn2+] ions. Thus, the optical absorption spectra of gold colloidal solution before and after the addition of Mn2+ ions reveal the concentration of Mn2+ ions in solution.

Narayanan, Kannan Badri; Park, Hyun Ho

2014-10-01

125

Electron spin resonance studies on quantum tunneling in spinel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The electron spin resonance (ESR) spectrometer, a very sensitive instrument with fast detecting window to explore quantum phase transitions for magnetic nanoparticles, was exploited to study the fascinating interplay between thermal and quantum fluctuations in the vicinity of a quantum critical point. We have measured ESR in ferrofluid samples containing nanosize particles of Fe2O3. The evolution of the ESR spectrum with temperature suggests that quantum tunneling of spins occurs in single domain magnetic particles in the low temperature regime. The effects of various microwave fields, particle sizes, and temperatures on the magnetic states of single domain spinel ferrite nanoparticles are investigated. We can consistently explain experimental data assuming that, as the temperature decreases, the spectrum changes from superparamagnetic (SPR) to blocked SPR and finally evolves quantum superparamagnetic behaviour as the temperature lowers down further. A nanoparticle system of a highly anisotropic magnetic material can be qualitatively specified by a simple quantum spin model, or by the Heisenberg model with strong easy-plane anisotropy.

Hsieh, C. T.; Lue, J. T.

2003-10-01

126

Distinguishing magnetic blocking and surface spin-glass freezing in nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles dispersed in SiO2 matrix have been synthesized by sol-gel method. Structural analysis has been performed by using x-ray diffraction and transmission electron microscopy. Magnetic properties have been investigated by using superconducting quantum interference device magnetometry. In addition to the average blocking temperature peak at TB=120 K measured by a zero field cooled temperature scan of the dc susceptibility, an additional hump near 15 K is observed. Temperature dependent out-of-phase ac susceptibility shows the same features: one broad peak at high temperature and a second narrow peak at low temperature. The high temperature peak corresponds to magnetic blocking of individual nanoparticles, while the low temperature peak is attributed to surface spin-glass freezing which becomes dominant for decreasing particle diameter. To prove the dynamics of the spin (dis)order in both regimes of freezing and blocking, the frequency dependent ac susceptibility is investigated under a biasing dc field. The frequency shift in the ``frozen'' low-temperature ac susceptibility peak is fitted to a dynamic scaling law with a critical exponent zv=7.5, which indicates a spin-glass phase. Exchange bias is turned on at low temperature which signifies the existence of a strong core-shell interaction. Aging and memory effects are further unique fingerprints of a spin-glass freezing on the surface of isolated magnetic nanoparticles.

Nadeem, K.; Krenn, H.; Traussing, T.; Letofsky-Papst, I.

2011-01-01

127

Dielectric properties of Mn0.5Zn0.5Fe2O4 ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Mn0.5Zn0.5Fe2O4 ferrite nanoparticles have been prepared by sol-gel auto-combustion method with a view to understand the role of oxidizer to fuel ratio (OFR) on the dielectric properties. XRD study shows the formation of cubic ferrite with spinel structure and particle size increases with the increase in concentration of fuel. Dielectric properties and AC conductivity of the sample measured at room temperature are reported. OFR plays a vital role in determining the dielectric properties and AC conductivity of the prepared samples.

Murugesan, C.; Md Gazzali, P. M.; Sathyamoorthy, B.; Chandrasekaran, G.

2013-02-01

128

Structural, Dielectric, FT-IR and Complex Impedance Properties of Cobalt Ferrite Nanoparticles  

NASA Astrophysics Data System (ADS)

Cobalt ferrite nanoparticles having the general formula CoFe2-xCuxO4 (0.0 <= x <= 0.5) were prepared by sol-gel method and characterized by using X-Ray diffraction (XRD), scanning electron microscopy (SEM ), Fourier transform infrared spectroscopy (FTIR), dielectric and impedance spectroscopy measurements. Confirmation of the single phase cubic spinel structure was made by using X-ray diffractometer. Lattice parameter `a' is found to decrease with increasing the doping contents. Debye- Scherer formula was used for finding the particle size and found in the range 30-45 nm. Morphological analysis was made by scanning electron microscopy which shows agglomerated flakes of particles having large pores on the surface. FT-IR spectra show two absorption bands assigned to the tetrahedral and octahedral complexes in the frequency range 400-600 cm-1. The variation of dielectric properties ?', V, tan? with frequency reveals that the dispersion is due to Maxwell-Wagner type of interfacial polarization. Impedance spectroscopy technique has been used to understand the conduction mechanism and to study the effect of grain and grain boundary on the electrical properties of the Cu doped CoFe2O4 ferrites.

Hashim, Mohd.; Alimuddin, Alimuddin; Ali, Sikander; Kumar, Shalendra; Kumar, Ravi

2011-11-01

129

Structural and magnetic properties correlated with cation distribution of Mo-substituted cobalt ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Mo-substituted cobalt ferrite nanoparticles; CoFe2-2xMoxO4 (0.0?x?0.3) were prepared by a one-step solution combustion synthesis technique. The reactants were metal nitrates and glycine as a fuel. The samples were characterized using an X-ray diffraction (XRD), a transmission electron microscope (TEM) and a vibrating sample magnetometer (VSM). XRD analysis revealed a pure single phase of cubic spinel ferrites for all samples with x up to 0.3. The lattice parameter decreases with Mo6+ substitution linearly up to x=0.15, then nonlinearly for x?0.2. Rietveld analysis and saturation magnetization (Ms) revealed that Mo6+ replaced Fe3+ in the tetrahedral A-sites up to x=0.15, then it replaced Fe3+ in both A-sites and B-sites for x?0.2. The saturation magnetization (Ms) increases with increasing Mo6+ substitution up to x=0.15 then decreases. The crystallite size decreased while the microstrain increased with increasing Mo6+ substitution. Inserting Mo6+ produces large residents of defects and cation vacancies.

Heiba, Z. K.; Mostafa, Nasser Y.; Abd-Elkader, Omar H.

2014-11-01

130

Enhanced magnetic properties of Dy3+ substituted Ni-Cu-Zn ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Dy3+ substituted Ni-Cu-Zn (Ni0.4Cu0.4Zn0.2DyxFe2-xO4) ferrite nanoparticles were obtained at 600 °C by synthesizing sol-gel auto-combustion method, and they exhibit a particle size of 12-21 nm. X-ray diffraction patterns confirm the presence of secondary phase of DyFeO3 and Fe2O3 for the Dy3+ substituted samples. Ni-Cu-Zn ferries doped with Dy3+ possess better grain structure and growth than that of pure Ni-Cu-Zn ferrite. The saturation magnetization increases remarkably up to 81 emu/g with increasing the Dy3+ ions. The increased saturation magnetization related to increased exchange interactions between Fe-Fe ions and also with increased particle size. Blocking temperature was found to decrease with increasing Dy3+ substitution. An enhancement in initial permeability and Curie temperature was observed with Dy3+ substitution.

Shirsath, Sagar E.; Kadam, R. H.; Patange, S. M.; Mane, M. L.; Ghasemi, Ali; Morisako, Akimitsu

2012-01-01

131

Preparation of magnesium ferrite nanoparticles by ultrasonic wave-assisted aqueous solution ball milling.  

PubMed

Magnesium ferrite, MgFe2O4 nanoparticles with high saturation magnetization were successfully synthesized using ultrasonic wave-assisted ball milling. In this study, the raw materials were 4MgCO3·Mg(OH)2·5H2O and Fe2O3 powders and the grinding media was stainless steel ball. The average particle diameter of the product MgFe2O4 powders was 20 nm and the saturation magnetization of them reached 54.8 emu/g. The different results of aqueous solution ball milling with and without ultrasonic wave revealed that it was the coupling effect of ultrasonic wave and mechanical force that played an important role during the synthesis of MgFe2O4. In addition, the effect of the frequency of the ultrasonic wave on the ball milling process was investigated. PMID:23622867

Chen, Ding; Li, Dian-yi; Zhang, Ying-zhe; Kang, Zhi-tao

2013-11-01

132

Cellular distribution and degradation of cobalt ferrite nanoparticles in Balb/3T3 mouse fibroblasts.  

PubMed

The effect of the concentration of cobalt ferrite (CoFe(2)O(4)) nanoparticles (NPs) on their intracellular location and distribution has been explored by synchrotron radiation X-ray and fluorescence microscopy (SR-XRF) monitoring the evolution of NPs elemental composition as well. In cells exposed to low concentrations of CoFe(2)O(4) NPs, the NPs preferentially segregate in the perinuclear region preserving their initial chemical content. At concentrations exceeding 500 ?M the XRF spectra indicate the presence of Co and Fe also in the nuclear region, accompanied by sensible changes in the cellular morphology. The increase of the Co/Fe ratio measured in the nuclear compartment indicates that above certain concentrations the CoFe(2)O(4) NPs intracellular distribution could be accompanied by biodegradation resulting in Co accumulation in the nucleus. PMID:21925252

Marmorato, Patrick; Ceccone, Giacomo; Gianoncelli, Alessandra; Pascolo, Lorella; Ponti, Jessica; Rossi, François; Salomé, Murielle; Kaulich, Burkhard; Kiskinova, Maya

2011-11-30

133

Experimental studies of cobalt ferrite nanoparticles doped silica matrix 3D magneto-photonic crystals  

NASA Astrophysics Data System (ADS)

In this paper, we present the synthesis and the optical properties of 3D magneto-photonic structures. The elaboration process consists in firstly preparing then infiltrating polystyrene direct opals with a homogeneous solution of sol-gel silica precursors doped by cobalt ferrite nanoparticles, and finally dissolving the polystyrene spheres. Scanning Electron Microscopy (SEM) images of the prepared samples clearly evidence a periodic arrangement. Using a home-made polarimetric optical bench, the transmittance as a function of the wavelength, the Faraday rotation as a function of the applied magnetic field, and the Faraday ellipticity as a function of the wavelength and as a function of the applied magnetic field were measured. The existence of deep photonic band gaps (PBG), the unambiguous magnetic character of the samples and the qualitative modification of the Faraday ellipticity in the area of the PBG are evidenced.

Abou Diwan, E.; Royer, F.; Kekesi, R.; Jamon, D.; Blanc-Mignon, M. F.; Neveu, S.; Rousseau, J. J.

2013-05-01

134

Fabrication of a glucose biosensor based on citric acid assisted cobalt ferrite magnetic nanoparticles.  

PubMed

A novel and practical glucose biosensor was fabricated with immobilization of Glucose oxidase (GOx) enzyme on the surface of citric acid (CA) assisted cobalt ferrite (CF) magnetic nanoparticles (MNPs). This innovative sensor was constructed with glassy carbon electrode which is represented as (GOx)/CA-CF/(GCE). An explicit high negative zeta potential value (-22.4 mV at pH 7.0) was observed on the surface of CA-CF MNPs. Our sensor works on the principle of detection of H2O2 which is produced by the enzymatic oxidation of glucose to gluconic acid. This sensor has tremendous potential for application in glucose biosensing due to the higher sensitivity 2.5 microA/cm2-mM and substantial increment of the anodic peak current from 0.2 microA to 10.5 microA. PMID:22962799

Krishna, Rahul; Titus, Elby; Chandra, Sudeshna; Bardhan, Neel Kanth; Krishna, Rohit; Bahadur, Dhirendra; Gracio, José

2012-08-01

135

The role of multi-walled carbon nanotubes on the magnetic and reflection loss characteristics of substituted strontium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Substituted strontium ferrite SrFe12-x(Ni0.5Mn0.5Zr)x/2O19/multi-walled carbon nanotubes (MWCNTs) composites were prepared by a sol-gel method. X-ray diffraction patterns confirm the formation of single phase ferrite nanoparticle and nanocomposites of ferrite/carbon nanotubes. Fourier transform infrared spectroscopy demonstrates the existence of functional groups on the surface of carbon nanotubes. Superconducting quantum interference device measurements showed that the values of specific saturation magnetization increases, while coercivity decreases with an increase in substitution content. Zero field cooled magnetization and field cooled magnetization curves display that with an increase in substitution content, the blocking temperature increases. Field emission scanning electron microscopy micrographs demonstrate that ferrite nanoparticles were attached on external surfaces of the carbon nanotubes. The investigation of the microwave absorption indicates that with an addition of carbon nanotubes, the real and imaginary parts of permittivity and reflection loss enhanced. It is found that with increasing the thickness of absorbers, the resonance frequencies shift to lower regime.

Ghasemi, Ali

2013-03-01

136

On the Effect of Manganese on Grain Size Stability and Hardenability in Ultrafine-Grained Ferrite/Martensite Dual-Phase Steels  

NASA Astrophysics Data System (ADS)

Two plain carbon steels with varying manganese content (0.87 wt pct and 1.63 wt pct) were refined to approximately 1 ?m by large strain warm deformation and subsequently subjected to intercritical annealing to produce an ultrafine grained ferrite/martensite dual-phase steel. The influence of the Mn content on microstructure evolution is studied by scanning electron microscopy (SEM). The Mn distribution in ferrite and martensite is analyzed by high-resolution electron backscatter diffraction (EBSD) combined with energy dispersive X-ray spectroscopy (EDX). The experimental findings are supported by the calculated phase diagrams, equilibrium phase compositions, and the estimated diffusion distances using Thermo-Calc (Thermo-Calc Software, McMurray, PA) and Dictra (Thermo-Calc Software). Mn substantially enhances the grain size stability during intercritical annealing and the ability of austenite to undergo martensitic phase transformation. The first observation is explained in terms of the alteration of the phase transformation temperatures and the grain boundary mobility, while the second is a result of the Mn enrichment in cementite during large strain warm deformation, which is inherited by the newly formed austenite and increases its hardenability. The latter is the main reason why the ultrafine-grained material exhibits a hardenability that is comparable with the hardenability of the coarse-grained reference material.

Calcagnotto, Marion; Ponge, Dirk; Raabe, Dierk

2012-01-01

137

Synthesis and coating of cobalt ferrite nanoparticles: a first step toward the obtainment of new magnetic nanocarriers.  

PubMed

Monodisperse and stable cobalt ferrite (CoFe2O4) nanoparticles (5.4 nm) have been produced, coated with mono- and difunctional phosphonic and hydroxamic acids, and fully characterized (using thermogravimetric analysis (TGA), dynamic light scattering (DLS), IR spectroscopy, transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID) measurements). Cobalt leakage of the coated nanoparticles has been also studied. Magnetic measurements show the possible applications in hyperthermia at low frequencies, and for this reason, water-soluble coated CoFe2O4 can be seen as a first step toward the obtainment of novel systems for biomagnetic applications. PMID:17335257

Baldi, Giovanni; Bonacchi, Daniele; Franchini, Mauro Comes; Gentili, Denis; Lorenzi, Giada; Ricci, Alfredo; Ravagli, Costanza

2007-03-27

138

Manganese Doping of Magnetic Iron Oxide Nanoparticles: Tailoring Surface Reactivity for a Regenerable Heavy Metal Sorbent  

SciTech Connect

A method for tuning the analyte affinity of magnetic, inorganic nanostructured sorbents for heavy metal contaminants is described. The manganese-doped iron oxide nanoparticle sorbents have a remarkably high affinity compared to the precursor material. Sorbent affinity can be tuned toward an analyte of interest simply by adjustment of the dopant quantity. The results show that following the Mn doping process there is a large increase in affinity and capacity for heavy metals (i.e., Co, Ni, Zn, As, Ag, Cd, Hg, and Tl). Capacity measurements were carried out for the removal of cadmium from river water and showed significantly higher loading than the relevant commercial sorbents tested for comparison. The reduction in Cd concentration from 100 ppb spiked river water to 1 ppb (less than the EPA drinking water limit of 5 ppb for Cd) was achieved following treatment with the Mn-doped iron oxide nanoparticles. The Mn-doped iron oxide nanoparticles were able to load 1 ppm of Cd followed by complete stripping and recovery of the Cd with a mild acid wash. The Cd loading and stripping is shown to be consistent through multiple cycles with no loss of sorbent performance.

Warner, Cynthia L.; Chouyyok, Wilaiwan; Mackie, Katherine E.; Neiner, Doinita; Saraf, Laxmikant; Droubay, Timothy C.; Warner, Marvin G.; Addleman, Raymond S.

2012-02-28

139

Formation of octapod MnO nanoparticles with enhanced magnetic properties through kinetically-controlled thermal decomposition of polynuclear manganese complexes  

NASA Astrophysics Data System (ADS)

Polynuclear manganese complexes are used as precursors for the synthesis of manganese oxide nanoparticles (MnO NPs). Altering the thermal decomposition conditions can shift the nanoparticle product from spherical, thermodynamically-driven NPs to unusual, kinetically-controlled octapod structures. The resulting increased surface area profoundly alters the NP's surface-dependent magnetism and may have applications in nanomedicine.Polynuclear manganese complexes are used as precursors for the synthesis of manganese oxide nanoparticles (MnO NPs). Altering the thermal decomposition conditions can shift the nanoparticle product from spherical, thermodynamically-driven NPs to unusual, kinetically-controlled octapod structures. The resulting increased surface area profoundly alters the NP's surface-dependent magnetism and may have applications in nanomedicine. Electronic supplementary information (ESI) available: Experimental details, TGA, TEM and diffraction data. See DOI: 10.1039/c3nr04832b

Douglas, Fraser J.; MacLaren, Donald A.; Tuna, Floriana; Holmes, William M.; Berry, Catherine C.; Murrie, Mark

2013-12-01

140

Lanthanum manganese perovskite nanoparticles as possible in vivo mediators for magnetic hyperthermia  

NASA Astrophysics Data System (ADS)

Manganese perovskite La 0.75Sr 0.25MnO 3 nanoparticles of the crystallite size 20-180 nm were prepared starting from citrate gel precursor by annealing in the range of 570-900 °C. It is shown that the decrease of the crystallite size leads to a gradual decrease of the magnetization and Curie temperature. The observed behaviour is a consequence of a non-collinear spin arrangement at the surface layer of crystallites, estimated to be of ˜5 nm. Magnetic heating experiments were carried out with an aqueous stable suspension of a selected sample ( M=42 emu/g, T=352 K) under an alternating field of H=88 mT, ?=108 kHz. The yielded values of specific absorption rate (SAR) were found to be larger than 500 W/g Mn at 27 °C and 350 W/g Mn at 37 °C.

Vasseur, S.; Duguet, E.; Portier, J.; Goglio, G.; Mornet, S.; Hadová, E.; Knížek, K.; Maryško, M.; Veverka, P.; Pollert, E.

2006-07-01

141

Manganese monoxide nanoparticles adhered to mesoporous nitrogen-doped carbons for nonaqueous lithium-oxygen batteries  

NASA Astrophysics Data System (ADS)

Manganese monoxide nanoparticles adhered to mesoporous nitrogen-doped carbons (MnO-m-N-C) have been synthesized and their influence on cycle performance of nonaqueous lithium-oxygen (Li-O2) batteries is investigated. It is found that the MnO-m-N-C composites promote both oxygen reduction and oxygen evolution reactions. They lead to reduced charge overpotentials through early decomposition of the Li2O2 particles formed on discharge, especially at the limited depth of discharge during the initial several ten cycles. Such superior activity is attributed to the good coupling between the nanosized MnO particles and the conductive mesoporous nitrogen-doped carbons, which is helpful for improving kinetics of both charge and mass transport during the cathode reactions.

Cui, Z. H.; Guo, X. X.

2014-12-01

142

Synthesis, structural investigation and magnetic properties of Zn2+ substituted cobalt ferrite nanoparticles prepared by the sol-gel auto-combustion technique  

NASA Astrophysics Data System (ADS)

Structural morphology and magnetic properties of the Co1-xZnxFe2O4 (0.0?x?1.0) spinel ferrite system synthesized by the sol-gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co-Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol-gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co-Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn2+ content in cobalt ferrite nanoparticles is followed by decrease in nB, Ms and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature.

Raut, A. V.; Barkule, R. S.; Shengule, D. R.; Jadhav, K. M.

2014-05-01

143

Functional Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields. Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy is a critical component in dispersion. Oleic acid is used to alter the surface of magnetite nanoparticles and successfully achieve good dispersion in a PMMA thin film. Polypyrrole is then coated onto the PMMA composite layer. The bilayer is characterized using cross-sectional TEM, cross-sectional SEM, magnetic characterization, and low frequency conductivity. The results show that the superparmagnetic properties of the as synthesized particles are maintained in the composite. With further study of the properties of these nanoparticles for real and functional uses, MCE is studied on a variety of magnetic nanoparticle systems. Magnetite, manganese zinc ferrite, and cobalt ferrite systems show significant broadening of the MCE and the ability to tune the peak temperature of MCE by varying the size of the nanoparticles. Four distinct systems are studied including cobalt, cobalt core silver shell nanoparticles, nickel ferrite, and ball milled zinc ferrite. The results demonstrate the importance of surface characteristics on MCE. Surface spin disorder appears to have a large influence on the low temperature magnetic and magnetocalorie characteristics of these nanoparticle systems.

Gass, James

144

Preliminary evaluation of a 99mTc labeled hybrid nanoparticle bearing a cobalt ferrite core: in vivo biodistribution.  

PubMed

Magnetic nanoparticles have become important tools for imaging a wide range of diseases, improving drug delivery and applying hyperthermic treatment. Iron oxide based nanoparticles have been widely examined, unlike cobalt ferrite based ones. Herein, monodisperse and stable CoFe2O4 nanoparticles have been produced, coated and further stabilized using ethyl 12-(hydroxyamino)-12-oxododecanoate, poly(lactic-co-glycolic acid) and bovine serum albumin. The final product, NBRh1, was fully characterized and has been directly radiolabeled with 99mTc using SnCl1 as the reducing agent in high yields. In vitro stability and hyperthermic properties of 99mTC-NBRh1 were encouraging for further application in low frequencies hyperthermia and biomagnetic applications. In vivo evaluation followed after injection in healthy mice. The planar and SPECT imaging data as well as the biodistribution results were in accordance, showing high liver and spleen uptake as expected starting almost immediately after administration. In conclusion the preliminary results for nanoparticles bearing a cobalt ferrite core justify further investigations towards potential hyperthermic applications, drug transportation and liver or spleen imaging. PMID:22852467

Psimadas, Dimitrios; Baldi, Giovanni; Ravagli, Costanza; Bouziotis, Penelope; Xanthopoulos, Stavros; Franchini, Mauro Comes; Georgoulias, Panagiotis; Loudos, George

2012-08-01

145

Manifestation of weak ferromagnetism and photocatalytic activity in bismuth ferrite nanoparticles  

SciTech Connect

Bismuth ferrite (BFO) nanoparticles were synthesized by auto-ignition technique with and without adding ignition fuel such as citric acid. The presence of citric acid in the reaction mixture yielded highly-magnetic BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite. When this composite was annealed to 650 Degree-Sign C, a single phase BFO was formed with average crystallite size of 50 nm and showed weak ferromagnetic behavior. Conversely, the phase pure BFO prepared without adding citric acid exhibited antiferromagnetism because of its larger crystallite size of around 70 nm. The visible-light driven photocatalytic activity of both the pure BFO and BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite were examined by degrading methyl orange dye. The pure BFO showed a moderate photocatalytic activity; while BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite showed enhanced activity. This could be probably due to the optimal band gap ratio between BFO and {gamma}-Fe{sub 2}O{sub 3} phases reduced the recombination of electron-hole pairs which aided in the enhancement of photocatalytic activity.

Sakar, M.; Balakumar, S. [National Center for Nanoscience and Nanotechnology, University of Madras, Chennai - 600025 (India); Saravanan, P. [Advanced Magnetics Group, Defence Metallurgical Research Laboratory, Hyderabad - 500 058 (India); Jaisankar, S. N. [Polymer Lab, Central Leather Research Laboratory, Adyar, Chennai - 600020 (India)

2013-02-05

146

Strontium ferrite nanoparticles synthesized in presence of polyvinylalcohol: Phase composition, microstructural and magnetic properties  

NASA Astrophysics Data System (ADS)

Systematic study was devoted to the synthesis of hexagonal strontium ferrite nanoparticles employing polyvinylalcohol as stabilizing agent. Preliminary experiments allowed to select an optimal sol having molar ratio Sr/Fe=12, weight ratio PVA/[Sr+Fe]=1.4 and pH=2.1. The obtained sol were transformed to gels by an evaporation of water at 100 °C and drying at 112 °C under vacuum. The subsequent calcination was carried out for 3 h at 400 °C, achieved by heating rate of 17 K/min. The obtained precursor was used for a detail study of influence of annealing conditions (temperature range 600-700 °C, annealing time 10-190 min) on the resulting properties. Semiquantitative X-ray phase analysis approved a gradual increase of the M-phase content and a gradual growth of M-phase crystallites with temperature and time. Magnetic measurements showed a distinct influence of the phase composition, namely ratio of the contents of M-phase and maghemite on the shape of the magnetic loops, while the crystallite sizes have only a slight effect.

Veverka, P.; Knížek, K.; Pollert, E.; Bohá?ek, J.; Vasseur, S.; Duguet, E.; Portier, J.

2007-02-01

147

Manifestation of weak ferromagnetism and photocatalytic activity in bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Bismuth ferrite (BFO) nanoparticles were synthesized by auto-ignition technique with and without adding ignition fuel such as citric acid. The presence of citric acid in the reaction mixture yielded highly-magnetic BFO/?-Fe2O3 nanocomposite. When this composite was annealed to 650°C, a single phase BFO was formed with average crystallite size of 50 nm and showed weak ferromagnetic behavior. Conversely, the phase pure BFO prepared without adding citric acid exhibited antiferromagnetism because of its larger crystallite size of around 70 nm. The visible-light driven photocatalytic activity of both the pure BFO and BFO/?-Fe2O3 nanocomposite were examined by degrading methyl orange dye. The pure BFO showed a moderate photocatalytic activity; while BFO/?-Fe2O3 nanocomposite showed enhanced activity. This could be probably due to the optimal band gap ratio between BFO and ?-Fe2O3 phases reduced the recombination of electron-hole pairs which aided in the enhancement of photocatalytic activity.

Sakar, M.; Balakumar, S.; Saravanan, P.; Jaisankar, S. N.

2013-02-01

148

Mössbauer and magnetic studies in nickel ferrite nanoparticles: Effect of size distribution  

NASA Astrophysics Data System (ADS)

The magnetic properties of nickel ferrite nanoparticles in the form of powders, prepared by the sol-gel process and subjected to different annealing temperatures, were investigated using both static and dynamic measurements namely hysteresis, zero field cooled-field cooled magnetization (ZFC-FC) measurements and Mössbauer spectroscopy. The Transmission Electron Microscopy (TEM) studies reveal particle sizes ˜2-8 nm for the as-prepared particles which increases upto 52 nm with annealing. A bimodal distribution, upto an annealing temperature of 300C was observed. ZFC-FC measurements for the as-prepared samples reveal twin peaks, indicative of the bimodal size distribution. ZFC-FC measurements performed for fields varying from 100 Oe to 3 kOe show a superparamagnetic phase with blocking temperatures between 320 and 85 K. Numerical simulations for the ZFC-FC studies indicate that the signature of the bimodal size distribution can be seen only at very low fields. The variation of coercivity with particle size, as determined from the hysteresis measurements, shows a transition from a single domain to a multi domain state for particle sizes larger than 35 nm. Mössbauer measurements performed at room temperature for the as-prepared sample shows a six finger pattern for the samples with higher particle size and a doublet pattern for the samples with smaller particle size, which is indicative of their superparamagnetic nature.

Malik, Rakesh; Annapoorni, S.; Lamba, Subhalakshmi; Raghavendra Reddy, V.; Gupta, Ajay; Sharma, Parmanand; Inoue, Akihisa

2010-12-01

149

Study Of Structural And Dielectric Properties Of Ni-Mg Ferrite Nanoparticles  

SciTech Connect

Ferrite nanoparticles of basic composition Ni{sub 0.7}Mg{sub 0.3}Fe{sub 2-x}Al{sub x}O{sub 4}(0.0{<=}x{<=}0.5) were prepared through citrate gel method and characterized using XRD, TEM and dielectric spectroscopy techniques. The dielectric properties were studied as a function of frequency (42 Hz-5 MHz) at room temperature. The average particle size has been found between 8-17 nm. The dispersion in dielectric properties and ac conductivity ({sigma}{sub ac}), with frequency reveals that the dispersion is due to Maxwell-Wagner type of interfacial polarization in general and the hopping of charge between Fe{sup 2+} and Fe{sup 3+} as well as between Ni{sup 2+} and Ni{sup 3+} ions at B-sites. The dielectric loss tangent (tan {delta}) shows abnormal behavior for the compositions 0.3, 0.4 and 0.5 which has been explained in the light of Rezlescue model.

Nongjai, Razia; Batoo, Khalid Mujasam; Khan, Shakeel [Dept. of Applied Physics, Aligarh Muslim University, Aligarh, 202002 (India) and King Abdullah Institute for Nanotechnology, King Saud University, Riyadh, 11451 (Saudi Arabia)

2010-12-01

150

Adsorption of cobalt ferrite nanoparticles within layer-by-layer films: a kinetic study carried out using quartz crystal microbalance.  

PubMed

The paper reports on the successful use of the quartz crystal microbalance technique to assess accurate kinetics and equilibrium parameters regarding the investigation of in situ adsorption of nanosized cobalt ferrite particles (CoFe(2)O(4)--10.5 nm-diameter) onto two different surfaces. Firstly, a single layer of nanoparticles was deposited onto the surface provided by the gold-coated quartz resonator functionalized with sodium 3-mercapto propanesulfonate (3-MPS). Secondly, the layer-by-layer (LbL) technique was used to build multilayers in which the CoFe(2)O(4) nanoparticle-based layer alternates with the sodium sulfonated polystyrene (PSS) layer. The adsorption experiments were conducted by modulating the number of adsorbed CoFe(2)O(4)/PSS bilayers (n) and/or by changing the CoFe(2)O(4) nanoparticle concentration while suspended as a stable colloidal dispersion. Adsorption of CoFe(2)O(4) nanoparticles onto the 3-MPS-functionalized surface follows perfectly a first order kinetic process in a wide range (two orders of magnitude) of nanoparticle concentrations. These data were used to assess the equilibrium constant and the adsorption free energy. Alternatively, the Langmuir adsorption constant was obtained while analyzing the isotherm data at the equilibrium. Adsorption of CoFe(2)O(4) nanoparticles while growing multilayers of CoFe(2)O(4)/PSS was conducted using colloidal suspensions with CoFe(2)O(4) concentration in the range of 10(-8) to 10(-6) (moles of cobalt ferrite per litre) and for different numbers of cycles n = 1, 3, 5, and 10. We found the adsorption of CoFe(2)O(4) nanoparticles within the CoFe(2)O(4)/PSS bilayers perfectly following a first order kinetic process, with the characteristic rate constant growing with the increase of CoFe(2)O(4) nanoparticle concentration and decreasing with the rise of the number of LbL cycles (n). Additionally, atomic force microscopy was employed for assessing the LbL film roughness and thickness. We found the film thickness increasing from about 20 to 120 nm while shifting from 3 to 10 CoFe(2)O(4)/PSS bilayers, using the 8.9 × 10(-6) (moles of cobalt ferrite per litre) suspension. PMID:22025281

Alcantara, Gustavo B; Paterno, Leonardo G; Afonso, André S; Faria, Ronaldo C; Pereira-da-Silva, Marcelo A; Morais, Paulo C; Soler, Maria A G

2011-12-28

151

A fast route to obtain manganese spinel nanoparticles by reduction of K-birnessite  

SciTech Connect

The K-birnessite (K{sub x}MnO{sub 2}.yH{sub 2}O) reduction reaction has been tested in order to obtain manganese spinel nanoparticles. The addition of 0.25 weight percent of hydrazine hydrate, the reducing agent, during 24 hours is efficient to transform the birnessite powder in a hausmanite Mn{sub 3}O{sub 4} powder. Well crystallised square shape nanoparticles are obtained. Different birnessite precursors have been tested and the reaction kinetics is strongly correlated to the crystallinity and granulometry of the precursor. The effects of aging time and hydrazine hydrate amount have been studied. Well crystallised Mn{sub 3}O{sub 4} is obtained in one hour. The presence of feitknechtite (MnO(OH)) and amorphous nanorods has been detected as an intermediate phase during birnessite conversion into hausmanite. The conversion mechanism is discussed. - Graphical abstract: TEM image showing Mn{sub 3}O{sub 4} particle after treatment of birnessite with an addition of hydrazine during 24 hours.

Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.f [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures 41029 BLOIS (France); Chartier, T. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures 41029 BLOIS (France); Autret-Lambert, C. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, parc de Grandmont 37200 TOURS (France); Delorme, F. [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 ORLEANS Cedex 2 (France); CORNING SAS, CETC, 7 bis Avenue Valvins, 77210 AVON (France); Zaghrioui, M. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures 41029 BLOIS (France); Seron, A. [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 ORLEANS Cedex 2 (France)

2009-05-15

152

Adsorption of sulfur dioxide by CoFe2O4 spinel ferrite nanoparticles and corresponding changes in magnetism.  

PubMed

Adsorption of sulfur dioxide on 10 nm CoFe(2)O(4) spinel ferrite nanoparticles was examined. Adsorption loadings of sulfur dioxide at breakthrough conditions were determined to be approximately 0.62 mol/kg, which is significant given the 150 m(2)/g surface area of the nanoparticles. Adsorption proceeds through a chemisorption mechanism with sulfur dioxide forming a sulfate upon adsorption on the particle surface, which leads to a 23% decrease in the remnant magnetization, a 20% decrease in the saturation magnetization, and a 9% decrease in the coercivity of the magnetic nanoparticles. Adsorbent materials that provide a magnetic signal when adsorption occurs could have broad implications on adsorption-based separations. PMID:22400990

Glover, T Grant; Sabo, Daniel; Vaughan, Lisa A; Rossin, Joseph A; Zhang, Z John

2012-04-01

153

The magnetic properties of plasma-sprayed thick-film manganese zinc ferrite (MZF) and nickel iron alloy (Permalloy) composites  

SciTech Connect

MnZn ferrite/Permalloy composites have potential in high frequency magnetic applications and can be made into thick-film devices by air plasma spray. The as-sprayed composites have lower saturation magnetization than the starting powder. After annealing below 600 deg. C, the magnetic properties and electrical resistivity improve significantly. The changes in magnetic and electrical properties were correlated to structural changes and studied by x-ray-diffraction analysis, vibrating-sample magnetometer measurements, and microstructural analysis.

Liang, S.; Gambino, R. J.; Sampath, S.; Raja, M. M. [Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York 11794 (United States)

2006-04-15

154

Synthesis of core/shell spinel ferrite/carbon nanoparticles with enhanced cycling stability for lithium ion battery anodes  

NASA Astrophysics Data System (ADS)

Monodispersed core/shell spinel ferrite/carbon nanoparticles are formed by thermolysis of metal (Fe3+, Co2+) oleates followed by carbon coating. The phase and morphology of nanoparticles are characterized by x-ray diffraction and transmission electron microscopy. Pure Fe3O4 and CoFe2O4 nanoparticles are initially prepared through thermal decomposition of metal-oleate precursors at 310?°C and they are found to exhibit poor electrochemical performance because of the easy aggregation of nanoparticles and the resulting increase in the interparticle contact resistance. In contrast, uniform carbon coating of Fe3O4 and CoFe2O4 nanoparticles by low-temperature (180?°C) decomposition of malic acid allowed each nanoparticle to be electrically wired to a current collector through a conducting percolative path. Core/shell Fe3O4/C and CoFe2O4/C nanocomposite electrodes show a high specific capacity that can exceed 700 mAh g-1 after 200 cycles, along with enhanced cycling stability.

Jin, Yun-Ho; Seo, Seung-Deok; Shim, Hyun-Woo; Park, Kyung-Soo; Kim, Dong-Wan

2012-03-01

155

Synthesis of core/shell spinel ferrite/carbon nanoparticles with enhanced cycling stability for lithium ion battery anodes.  

PubMed

Monodispersed core/shell spinel ferrite/carbon nanoparticles are formed by thermolysis of metal (Fe3+, Co2+) oleates followed by carbon coating. The phase and morphology of nanoparticles are characterized by x-ray diffraction and transmission electron microscopy. Pure Fe3O4 and CoFe2O4 nanoparticles are initially prepared through thermal decomposition of metal–oleate precursors at 310 degrees C and they are found to exhibit poor electrochemical performance because of the easy aggregation of nanoparticles and the resulting increase in the interparticle contact resistance. In contrast, uniform carbon coating of Fe3O4 and CoFe2O4 nanoparticles by low-temperature (180 degrees C) decomposition of malic acid allowed each nanoparticle to be electrically wired to a current collector through a conducting percolative path. Core/shell Fe3O4/C and CoFe2O4/C nanocomposite electrodes show a high specific capacity that can exceed 700 mAh g(-1) after 200 cycles, along with enhanced cycling stability. PMID:22414887

Jin, Yun-Ho; Seo, Seung-Deok; Shim, Hyun-Woo; Park, Kyung-Soo; Kim, Dong-Wan

2012-03-30

156

Microwave-absorbing characteristics of epoxy resin composites containing nanoparticles of NiZn- and NiCuZn-ferrites  

Microsoft Academic Search

NiZn- and NiCuZn-ferrite nanoparticles (50–70nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83emu\\/g (NiZn) to 91emu\\/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in the frequency range

J. C. Aphesteguy; Abel Damiani; Dalmas DiGiovanni; S. E. Jacobo

2009-01-01

157

Microwave-absorbing characteristics of epoxy resin composites containing nanoparticles of NiZn- and NiCuZn-ferrites  

Microsoft Academic Search

NiZn- and NiCuZn-ferrite nanoparticles (50-70 nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83 emu\\/g (NiZn) to 91 emu\\/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in

J. C. Aphesteguy; Abel Damiani; Dalmas Digiovanni; S. E. Jacobo

2009-01-01

158

Optical emission spectroscopy as a tool for the biodistribution investigation of cobalt-ferrite nanoparticles in mice  

NASA Astrophysics Data System (ADS)

This study reports on the biodistribution investigation of two magnetic samples both based on cobalt-ferrite nanoparticles, a magnetic fluid sample (CoMF) and a stealth magnetoliposome polyethylene glycol-monolaurate (PEG-ML). Morphology observations and iron and cobalt concentrations were evaluated after treatment of mice upon intravenous injection. Both magnetic samples had an extended distribution throughout all investigated organs. CoMF was quickly eliminated mainly by the fecal via whereas PEG-ML was retained longer in the circulation and slowly eliminated. These differences are probably due to the presence of polyethylene glycol on the PEG-ML surface, recognized to be responsible for the internalization delay of nanoparticles.

Kückelhaus, S.; Tedesco, A. C.; Oliveira, D. M.; Morais, P. C.; Boaventura, G. R.; Lacava, Z. G. M.

2005-05-01

159

Manganese-impregnated mesoporous silica nanoparticles for signal enhancement in MRI cell labelling studies.  

PubMed

Mesoporous silica nanoparticles (MSNs) are used in drug delivery and cell tracking applications. As Mn(2+) is already implemented as a "positive" cell contrast agent in preclinical imaging procedures (in the form of MnCl2 for neurological studies), the introduction of Mn in the porous network of MSNs would allow labelling cells and tracking them using MRI. These particles are in general internalized in endosomes, an acidic environment with high saline concentration. In addition, the available MSN porosity could also serve as a carrier to deliver medical/therapeutic substances through the labelled cells. In the present study, manganese oxide was introduced in the porous network of MCM-48 silica nanoparticles (Mn-M48SNs). The particles exhibit a narrow size distribution (~140 nm diam.) and high porosity (~60% vol.), which was validated after insertion of Mn. The resulting Mn-M48SNs were characterized by TEM, N2 physisorption, and XRD. Evidence was found with H2-TPR, and XPS characterization, that Mn(II) is the main oxidation state of the paramagnetic species after suspension in water, most probably in the form of Mn-OOH. The colloidal stability as a function of time was confirmed by DLS in water, acetate buffer and cell culture medium. In NMR data, no significant evidence of Mn(2+) leaching was found in Mn-M48SNs in acidic water (pH 6), up to 96 hours after suspension. High longitudinal relaxivity values of r1 = 8.4 mM(-1) s(-1) were measured at 60 MHz and 37 °C, with the lowest relaxometric ratios (r2/r1 = 2) reported to date for a Mn-MSN system. Leukaemia cells (P388) were labelled with Mn-M48SNs and nanoparticle cell internalization was confirmed by TEM. Finally, MRI contrast enhancement provided by cell labelling with escalated incubation concentrations of Mn-M48SNs was quantified at 1 T. This study confirmed the possibility of efficiently confining Mn into M48SNs using incipient wetness, while maintaining an open porosity and relatively high pore volume. Because these Mn-labelled M48SNs express strong "positive" contrast media properties at low concentrations, they are potentially applicable for cell tracking and drug delivery methodologies. PMID:24178890

Guillet-Nicolas, Rémy; Laprise-Pelletier, Myriam; Nair, Mahesh M; Chevallier, Pascale; Lagueux, Jean; Gossuin, Yves; Laurent, Sophie; Kleitz, Freddy; Fortin, Marc-André

2013-12-01

160

Low temperature-fired Ni-Cu-Zn ferrite nanoparticles through auto-combustion method for multilayer chip inductor applications  

PubMed Central

Ferrite nanoparticles of basic composition Ni0.7-xZnxCu0.3Fe2O4 (0.0 ? x ? 0.2, x = 0.05) were synthesized through auto-combustion method and were characterized for structural properties using X-ray diffraction [XRD], scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy [FT-IR]. XRD analysis of the powder samples sintered at 600°C for 4 h showed the cubic spinel structure for ferrites with a narrow size distribution from 28 to 32 nm. FT-IR showed two absorption bands (v1 and v2) that are attributed to the stretching vibration of tetrahedral and octahedral sites. The effect of Zn doping on the electrical properties was studied using dielectric and impedance spectroscopy at room temperature. The dielectric parameters (?', ??, tan?, and ?ac) show their maximum value for 10% Zn doping. The dielectric constant and loss tangent decrease with increasing frequency of the applied field. The results are explained in the light of dielectric polarization which is similar to the conduction phenomenon. The complex impedance shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume. PACS: 75.50.Gg; 78.20; 77.22.Gm.

2012-01-01

161

Regio- and chemoselective reduction of nitroarenes and carbonyl compounds over recyclable magnetic ferrite-nickel nanoparticles (Fe(3)O(4)-Ni) by using glycerol as a hydrogen source.  

PubMed

Reduction by magnetic nano-Fe(3)O(4)-Ni: a facile, simple and environmentally friendly hydrogen-transfer reaction that takes place over recyclable ferrite-nickel magnetic nanoparticles (Fe(3)O(4)-Ni) by using glycerol as hydrogen source allows aromatic amines and alcohols to be synthesized from the precursor nitroarenes and carbonyl compounds. PMID:22933355

Gawande, Manoj B; Rathi, Anuj K; Branco, Paula S; Nogueira, Isabel D; Velhinho, Alexandre; Shrikhande, Janhavi J; Indulkar, Utkarsha U; Jayaram, Radha V; Ghumman, C Amjad A; Bundaleski, Nenad; Teodoro, Orlando M N D

2012-10-01

162

Microwave Absorption Properties of Mn–Co–Sn Doped Barium Ferrite Nanoparticles  

Microsoft Academic Search

Substituted barium ferrite BaFe9(Mn0.5Co0.5Sn)3\\/2O19 was prepared by sol-gel method. X-ray diffraction (XRD), transmission electron microscope (TEM), AC susceptometer, vibrating sample magnetometer (VSM) and vector network analyzer were used to analyze the structure, static and dynamic magnetic properties of the prepared samples. The prepared ferrite particles possess irregular non spherical shape with a broad size distribution. The substitution was very effective

Ali Ghasemi; Vladimir Sepelak; Xiaoxi Liu; Akimitsu Morisako

2009-01-01

163

An integrated study of thermal treatment effects on the microstructure and magnetic properties of Zn-ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The evolution of the magnetic state, crystal structure and microstructure parameters of nanocrystalline zinc-ferrite, tuned by thermal annealing of ˜4 nm nanoparticles, was systematically studied by complementary characterization methods. Structural analysis of neutron and synchrotron x-ray radiation data revealed a mixed cation distribution in the nanoparticle samples, with the degree of inversion systematically decreasing from 0.25 in an as-prepared nanocrystalline sample to a non-inverted spinel structure with a normal cation distribution in the bulk counterpart. The results of DC magnetization and Mössbauer spectroscopy experiments indicated a superparamagnetic relaxation in ˜4 nm nanoparticles, albeit with different freezing temperatures Tf of 27.5 K and 46 K, respectively. The quadrupole splitting parameter decreases with the annealing temperature due to cation redistribution between the tetrahedral and octahedral sites of the spinel structure and the associated defects. DC magnetization measurements indicated the existence of significant interparticle interactions among nanoparticles (‘superspins’). Additional confirmation for the presence of interparticle interactions was found from the fit of the Tf(H) dependence to the AT line, from which a value of the anisotropy constant of Keff = 5.6 × 105 erg cm-3 was deduced. Further evidence for strong interparticle interactions was found from AC susceptibility measurements, where the frequency dependence of the freezing temperature Tf(f) was satisfactory described by both Vogel-Fulcher and dynamic scaling theory, both applicable for interacting systems. The parameters obtained from these fits suggest collective freezing of magnetic moments at Tf.

Antic, Bratislav; Perovic, Marija; Kremenovic, Aleksandar; Blanusa, Jovan; Spasojevic, Vojislav; Vulic, Predrag; Bessais, Lotfi; Bozin, Emil S.

2013-02-01

164

Manganese-impregnated mesoporous silica nanoparticles for signal enhancement in MRI cell labelling studies  

NASA Astrophysics Data System (ADS)

Mesoporous silica nanoparticles (MSNs) are used in drug delivery and cell tracking applications. As Mn2+ is already implemented as a ``positive'' cell contrast agent in preclinical imaging procedures (in the form of MnCl2 for neurological studies), the introduction of Mn in the porous network of MSNs would allow labelling cells and tracking them using MRI. These particles are in general internalized in endosomes, an acidic environment with high saline concentration. In addition, the available MSN porosity could also serve as a carrier to deliver medical/therapeutic substances through the labelled cells. In the present study, manganese oxide was introduced in the porous network of MCM-48 silica nanoparticles (Mn-M48SNs). The particles exhibit a narrow size distribution (~140 nm diam.) and high porosity (~60% vol.), which was validated after insertion of Mn. The resulting Mn-M48SNs were characterized by TEM, N2 physisorption, and XRD. Evidence was found with H2-TPR, and XPS characterization, that Mn(ii) is the main oxidation state of the paramagnetic species after suspension in water, most probably in the form of Mn-OOH. The colloidal stability as a function of time was confirmed by DLS in water, acetate buffer and cell culture medium. In NMR data, no significant evidence of Mn2+ leaching was found in Mn-M48SNs in acidic water (pH 6), up to 96 hours after suspension. High longitudinal relaxivity values of r1 = 8.4 mM-1 s-1 were measured at 60 MHz and 37 °C, with the lowest relaxometric ratios (r2/r1 = 2) reported to date for a Mn-MSN system. Leukaemia cells (P388) were labelled with Mn-M48SNs and nanoparticle cell internalization was confirmed by TEM. Finally, MRI contrast enhancement provided by cell labelling with escalated incubation concentrations of Mn-M48SNs was quantified at 1 T. This study confirmed the possibility of efficiently confining Mn into M48SNs using incipient wetness, while maintaining an open porosity and relatively high pore volume. Because these Mn-labelled M48SNs express strong ``positive'' contrast media properties at low concentrations, they are potentially applicable for cell tracking and drug delivery methodologies.Mesoporous silica nanoparticles (MSNs) are used in drug delivery and cell tracking applications. As Mn2+ is already implemented as a ``positive'' cell contrast agent in preclinical imaging procedures (in the form of MnCl2 for neurological studies), the introduction of Mn in the porous network of MSNs would allow labelling cells and tracking them using MRI. These particles are in general internalized in endosomes, an acidic environment with high saline concentration. In addition, the available MSN porosity could also serve as a carrier to deliver medical/therapeutic substances through the labelled cells. In the present study, manganese oxide was introduced in the porous network of MCM-48 silica nanoparticles (Mn-M48SNs). The particles exhibit a narrow size distribution (~140 nm diam.) and high porosity (~60% vol.), which was validated after insertion of Mn. The resulting Mn-M48SNs were characterized by TEM, N2 physisorption, and XRD. Evidence was found with H2-TPR, and XPS characterization, that Mn(ii) is the main oxidation state of the paramagnetic species after suspension in water, most probably in the form of Mn-OOH. The colloidal stability as a function of time was confirmed by DLS in water, acetate buffer and cell culture medium. In NMR data, no significant evidence of Mn2+ leaching was found in Mn-M48SNs in acidic water (pH 6), up to 96 hours after suspension. High longitudinal relaxivity values of r1 = 8.4 mM-1 s-1 were measured at 60 MHz and 37 °C, with the lowest relaxometric ratios (r2/r1 = 2) reported to date for a Mn-MSN system. Leukaemia cells (P388) were labelled with Mn-M48SNs and nanoparticle cell internalization was confirmed by TEM. Finally, MRI contrast enhancement provided by cell labelling with escalated incubation concentrations of Mn-M48SNs was quantified at 1 T. This study confirmed the possibility of efficiently confining Mn into M48SNs using incipient wetness

Guillet-Nicolas, Rémy; Laprise-Pelletier, Myriam; Nair, Mahesh M.; Chevallier, Pascale; Lagueux, Jean; Gossuin, Yves; Laurent, Sophie; Kleitz, Freddy; Fortin, Marc-André

2013-11-01

165

Preparation of magnetic photocatalyst nanoparticles—TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite—and its photocatalytic activity influenced by silica interlayer  

SciTech Connect

Highlights: ? TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite acts as magnetic photocatalyst nanoparticle. ? SiO{sub 2} interlayer is used to prevent electron migration between photocatalyst and magnetic core. ? TiO{sub 2}/Mn–Zn ferrite without SiO{sub 2} interlayer shows poor magnetic and photocatalytic property. -- Abstract: A magnetic photocatalyst, TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite, was prepared by stepwise synthesis involving the co-precipitation of Mn–Zn ferrite as a magnetic core, followed by a coating of silica as the interlayer, and titania as the top layer. The particle size and distribution of magnetic nanoparticles were found to depend on the addition rate of reagent and dispersing rate of reaction. The X-ray diffractometer and transmission electron microscope were used to examine the crystal structures and the morphologies of the prepared composites. Vibrating sample magnetometer was also used to reveal their superparamagnetic property. The UV–Vis spectrophotometer was employed to monitor the decomposition of methylene blue in the photocatalytic efficient study. It was found that at least a minimum thickness of the silica interlayer around 20 nm was necessary for the inhibition of electron transference initiated by TiO{sub 2} and Mn–Zn ferrite.

Laohhasurayotin, Kritapas, E-mail: kritapas@nanotec.or.th [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)] [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand); Pookboonmee, Sudarat; Viboonratanasri, Duangkamon; Kangwansupamonkon, Wiyong [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)] [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)

2012-06-15

166

Synthesis and magnetic properties of CoFe{sub 2}O{sub 4} spinel ferrite nanoparticles doped with lanthanide ions  

SciTech Connect

Lanthanide ions have been doped into cobalt spinel ferrites using an oil-in-water micellar method to form CoLn{sub 0.12}Fe{sub 1.88}O{sub 4} nanoparticles with Ln=Ce, Sm, Eu, Gd, Dy, or Er. Doping with lanthanide ions (Ln{sup III}) modulates the magnetic properties of cobalt spinel ferrite nanoparticles. In particular cases of Gd{sup 3+} or Dy{sup 3+} ions, a dramatic increase in the blocking temperature and coercivity is observed. Indeed, the introduction of only 4% of Gd{sup 3+} ions increases the blocking temperature {similar_to}100 K and the coercivity 60%. Initial studies on the magnetic properties of these doped nanoparticles clearly demonstrate that the relationship between the modulation of magnetic properties and the nature of doped Ln{sup III} ions is interesting but very complex. {copyright} 2001 American Institute of Physics.

Kahn, Myrtil L.; Zhang, Z. John

2001-06-04

167

Two-, three-, and four-component magnetic multilayer onion nanoparticles based on iron oxides and manganese oxides.  

PubMed

Magnetic multilayered, onion-like, heterostructured nanoparticles are interesting model systems for studying magnetic exchange coupling phenomena. In this work, we synthesized heterostructured magnetic nanoparticles composed of two, three, or four components using iron oxide seeds for the subsequent deposition of manganese oxide. The MnO layer was allowed either to passivate fully in air to form an outer layer of Mn(3)O(4) or to oxidize partially to form MnO|Mn(3)O(4) double layers. Through control of the degree of passivation of the seeds, particles with up to four different magnetic layers can be obtained (i.e., FeO|Fe(3)O(4)|MnO|Mn(3)O(4)). Magnetic characterization of the samples confirmed the presence of the different magnetic layers. PMID:21973012

Salazar-Alvarez, German; Lidbaum, Hans; López-Ortega, Alberto; Estrader, Marta; Leifer, Klaus; Sort, Jordi; Suriñach, Santiago; Baró, Maria Dolors; Nogués, Josep

2011-10-26

168

Magnetically driven micropump produced by microstereolithography with ferrite nanoparticle composite photopolymer  

Microsoft Academic Search

A photopolymer containing magnetic nanoparticles was developed for applying magnetically driven micromachines. 7-nm diameter gamma-Fe2O3 nanoparticles coated by amorphous-SiO2 was used. The concentration of the magnetic nanoparticles was optimized by ultraviolet exposure. A magnetic microrotor of 6 mm diameter was produced by a molding process with a three-dimensional master model produced by microstereolithography using the nanoparticle composite photopolymer. A viscous

S. Maruo; T. Saeki; Y. Kanazawa; Y. Ichiyanagi

2008-01-01

169

Magnetic and structural studies of nickel-substituted cobalt ferrite nanoparticles, synthesized by the sol-gel method  

NASA Astrophysics Data System (ADS)

In this study Ni substituted cobalt ferrite nanoparticles (NixCo1-xFe2O4 where x=0.1, 0.3, 0.5, 0.7 and 0.9) were prepared by the sol-gel method. Phase identification of the samples was performed by the X-ray diffraction (XRD) method and the mean crystallite sizes of the samples were obtained using Scherrer's formula. The results show that a minimum calcining temperature of 500 °C is required to obtain single phase spinel structures for all the samples. It was observed that the lattice parameter of the samples decreases from 8.350 to 8.300 Å with increasing Ni content. Morphology of the samples was investigated by a field emission scanning electron microscope (FESEM). Also mean particle sizes of the samples were obtained from FESEM images and there no relation between particle size and Ni content was found. Magnetic measurements were carried out on the cold pressed samples and the results show that saturation magnetization decreases as x increases. Curie temperatures of the samples were determined and the results show that by increasing x values their Curie temperatures increase. This increase was explained based on the change in superexchange interactions between magnetic ions by substitution of Ni ions in Co ferrite. Also the coercive forces of the samples decreased with increasing x values which was explained by the changes in magnetocrystalline anisotropy.

Mozaffari, M.; Amighian, J.; Darsheshdar, E.

2014-01-01

170

Control of the Size of Cobalt Ferrite Nanoparticles : Synthesis and Properties  

Microsoft Academic Search

The preparation of a fluid of cobalt ferrite particles having a size varying from 2 to 5nm is described. This bas been achieved by using functionalized surfactants. The size of cobalt femte particles decreases when the total reactant concentration decreases. The magnetic properties are described with magnetization curves and \\

M. P. Pileni; N. Moumen; J. F. Hochepied; P. Bonville; P. Veillet

1997-01-01

171

Magnetic properties and densification of Manganese-Zinc soft ferrites (Mn 1-xZn xFe 2O 4) doped with low melting point oxides  

NASA Astrophysics Data System (ADS)

Mn-Zn ferrites have high electrical resistivity, low power loss and high initial permeability up to several MHz range. Oxide additives can greatly affect the magnetic properties of these ferrites. The effects of the additives on the sintering behaviour and magnetic properties of Mn-Zn ferrites are different. Some low melting point additives such as Bi 2O 3 enhance the sintering by forming a liquid phase in the ferrites. The additive V 2O 5 enhances the sintering by increasing bulk diffusion due to the increased vacancy concentration which is accompanied by the solubility of V 5+ in the ferrites. Some additives are cations that are soluble in the host lattice and enter regular positions on the tetrahedral or octahedral sites. This paper investigates the effect of several low melting point oxides on the magnetic properties, microstructure and densification of Mn-Zn soft ferrites.

Shokrollahi, H.

172

X-ray photoelectron spectroscopy and friction studies of nickel-zinc and manganese-zinc ferrites in contact with metals  

NASA Technical Reports Server (NTRS)

X-ray photoelectron spectroscopy analysis and sliding friction experiments were conducted with hot-pressed, polycrystalline Ni-Zn and Mn-Zn ferrites in sliding contact with various transition metals at room temperature in a vacuum of 30 nPa. The results indicate that the coefficients of friction for Ni-Zn and Mn-Zn ferrites in contact with metals are related to the relative chemical activity in these metals: the more active the metal, the higher is the coefficient of friction. The coefficients of friction for the ferrites correlate with the free energy of formation of the lowest metal oxide. The interfacial bond can be regarded as a chemical bond between the metal atoms and the oxygen anions in the ferrite surfaces. The adsorption of oxygen on clean metal and ferrite surfaces increases the coefficients of friction for the Ni-Zn and Mn-Zn ferrite-metal interfaces.

Miyoshi, K.; Buckley, D. H.

1983-01-01

173

Magnetic properties and densification of Manganese–Zinc soft ferrites (Mn 1-xZn xFe 2O 4) doped with low melting point oxides  

Microsoft Academic Search

Mn–Zn ferrites have high electrical resistivity, low power loss and high initial permeability up to several MHz range. Oxide additives can greatly affect the magnetic properties of these ferrites. The effects of the additives on the sintering behaviour and magnetic properties of Mn–Zn ferrites are different. Some low melting point additives such as Bi2O3 enhance the sintering by forming a

H. Shokrollahi

2008-01-01

174

Self-assembled organic-inorganic magnetic hybrid adsorbent ferrite based on cyclodextrin nanoparticles.  

PubMed

Organic-inorganic magnetic hybrid materials (MHMs) combine a nonmagnetic and a magnetic component by means of electrostatic interactions or covalent bonds, and notable features can be achieved. Herein, we describe an application of a self-assembled material based on ferrite associated with ?-cyclodextrin (Fe-Ni/Zn/?CD) at the nanoscale level. This MHM and pure ferrite (Fe-Ni/Zn) were used as an adsorbent system for Cr(3+) and Cr(2)O(7) (2-) ions in aqueous solutions. Prior to the adsorption studies, both ferrites were characterized in order to determine the particle size distribution, morphology and available binding sites on the surface of the materials. Microscopy analysis demonstrated that both ferrites present two different size domains, at the micro- and nanoscale level, with the latter being able to self-assemble into larger particles. Fe-Ni/Zn/?CD presented smaller particles and a more homogeneous particle size distribution. Higher porosity for this MHM compared to Fe-Ni/Zn was observed by Brunauer-Emmett-Teller isotherms and positron-annihilation-lifetime spectroscopy. Based on the pKa values, potentiometric titrations demonstrated the presence of ?CD in the inorganic matrix, indicating that the lamellar structures verified by transmission electronic microscopy can be associated with ?CD assembled structures. Colloidal stability was inferred as a function of time at different pH values, indicating the sedimentation rate as a function of pH. Zeta potential measurements identified an amphoteric behavior for the Fe-Ni/Zn/?CD, suggesting its better capability to remove ions (cations and anions) from aqueous solutions compared to that of Fe-Ni/Zn. PMID:23209524

Denadai, Angelo M L; De Sousa, Frederico B; Passos, Joel J; Guatimosim, Fernando C; Barbosa, Kirla D; Burgos, Ana E; de Oliveira, Fernando Castro; da Silva, Jeann C; Neves, Bernardo R A; Mohallem, Nelcy D S; Sinisterra, Rubén D

2012-01-01

175

Synthesis of MPTS-modified cobalt ferrite nanoparticles and their adsorption properties in relation to Au(III).  

PubMed

Cobalt ferrite magnetic nanoparticles (Co-MNP) were prepared by a co-precipitation method and subsequently coated with (3-mercaptopropyl)trimethoxysilane (MPTS) for the extraction and recovery of Au(III) from aqueous chloride solutions. Physical characterization of the MPTS-modified particles (Co-MPTS) was performed using FT-IR, TGA, and SEM. Results from FT-IR confirmed that MPTS was present on the surface of the magnetic nanoparticles. The amount of MPTS was 0.36 mmol g(-1) of Co-MPTS, obtained by elemental analysis. SEM images revealed aggregates composed of nanocrystalline Co-MPTS particles. The extraction efficiency as a function of the pH, contact time, and initial Au(III) concentration was evaluated. The modified particles showed maximum adsorption in the pH range from 1.0 to 4.0. The adsorption behavior of Co-MPTS toward Au(III) followed a Langmuir isotherm and the maximum adsorption capacity was found to be 120.5 mg g(-1). The stability of the modified materials was improved as compared to that of bare Co-MNP. The subsequent desorption of gold could be achieved by using acidified thiourea solution; the highest gold recovery reached 85%. PMID:19647836

Kraus, Andrea; Jainae, Kunawoot; Unob, Fuangfa; Sukpirom, Nipaka

2009-10-15

176

Synthesis and characterization of zinc ferrite nanoparticles by a thermal treatment method  

NASA Astrophysics Data System (ADS)

Crystalline zinc ferrite (ZnFe 2O 4) was prepared by the thermal treatment method, followed by calcination at various temperatures from 723 to 873 K. Poly (vinyl pyrrolidon) (PVP) was used as a capping agent to stabilize the particles and prevent them from agglomeration. The characterization studies were conducted by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average particle sizes of 17-31 nm were obtained by TEM images, which were in good agreement with the XRD results. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of metal oxide bands at all temperatures and the absence of organic bands at 873 K. The magnetic properties were demonstrated by a vibrating sample magnetometer (VSM), which displayed super paramagnetic behaviors for the calcined samples. The present study also substantiated that, in ferrites, the values of the quantities that were acquired by VSM, such as the saturation magnetization and coercivity field, are primarily dependent on the methods of preparation of the ferrites. Electron paramagnetic resonance (EPR) spectroscopy showed the existence of unpaired electrons and measured the peak-to-peak line width ( ?H), the resonant magnetic field ( Hr), and the g-factor values.

Naseri, Mahmoud Goodarz; Saion, Elias B.; Hashim, Mansor; Shaari, Abdul Halim; Ahangar, Hossein Abasstabar

177

Development of phosphonate modified Fe (1? x) Mn x Fe 2O 4 mixed ferrite nanoparticles: Novel peroxidase mimetics in enzyme linked immunosorbent assay  

Microsoft Academic Search

A highly facile and feasible strategy on the fabrication of advanced intrinsic peroxidase mimetics based on Mn2+ doped mixed ferrite (MnIIxFeII1?xFeIII2O4) nanoparticles was demonstrated for the quantitative and sensitive detection of mouse IgG (as a model analyte). Mn2+ doped Fe1?xMnxFe2O4 nanoparticles were synthesized using varying ratios of Mn2+:Fe2+ ions and characterized by the well known complementary techniques. The increase of

Dipsikha Bhattacharya; Ananya Baksi; Indranil Banerjee; Rajakumar Ananthakrishnan; Tapas K. Maiti; Panchanan Pramanik

2011-01-01

178

Anatase TiO 2 nanolayer coating on cobalt ferrite nanoparticles for magnetic photocatalyst  

Microsoft Academic Search

TiO2\\/CoFe2O4 composite nanoparticles with a core–shell structure have been obtained. The core CoFe2O4 nanoparticles were synthesized via co-precipitation method, and the shell TiO2 nanocrystals were derived via sol–gel technology followed by heat-treatment at 450 °C. The morphology and the crystalline structure of composite nanoparticles were characterized by transmission electron microscopy (TEM) and X-ray diffraction, respectively. The as-prepared composite particles can

Wuyou Fu; Haibin Yang; Minghua Li; Minghui Li; Nan Yang; Guangtian Zou

2005-01-01

179

Superparamagnetic Particle Size Limit of Mn-Zn Ferrite Nanoparticles Synthesised Through Aqueous Method  

SciTech Connect

Mn0.67Zn0.33Fe2O4 nanoparticles with size ranging from 20 to 80 nm have been synthesized using the modified oxidation method. The Curie temperatures for all the samples are found to be within 630 {+-} 5 K suggesting that there is no size-dependent cation distribution. Moessbauer studies on the synthesized nanoparticles suggest that the critical particle size limit for superparamagnetism to be about 25 nm at 293 K.

Joseyphus, R. Justin [Graduate School of Environmental Studies, Tohoku University, AramakiAza Aoba-ku, Sendai 980-8579 (Japan); Materials Science Centre, Dept. of Nuclear Physics, University of Madras, Guindy Campus, Chennai-25 (India); Narayanasamy, A. [Materials Science Centre, Dept. of Nuclear Physics, University of Madras, Guindy Campus, Chennai-25 (India); Jeyadevan, B.; Shinoda, K.; Tohji, K. [Graduate School of Environmental Studies, Tohoku University, AramakiAza Aoba-ku, Sendai 980-8579 (Japan)

2006-05-15

180

Superparamagnetic Particle Size Limit of Mn-Zn Ferrite Nanoparticles Synthesised Through Aqueous Method  

Microsoft Academic Search

Mn0.67Zn0.33Fe2O4 nanoparticles with size ranging from 20 to 80 nm have been synthesized using the modified oxidation method. The Curie temperatures for all the samples are found to be within 630 +\\/- 5 K suggesting that there is no size-dependent cation distribution. Mössbauer studies on the synthesized nanoparticles suggest that the critical particle size limit for superparamagnetism to be about

R. Justin Joseyphus; A. Narayanasamy; B. Jeyadevan; K. Shinoda; K. Tohji

2006-01-01

181

Self-assembly of manganese oxide nanoparticles and hollow spheres. Catalytic activity in carbon monoxide oxidation.  

PubMed

Reactions between MnSO(4) and KMnO(4) in the presence of carboxylic acids provide a facile, one-pot route to nanostructured manganese oxides with high surface areas. Acetic and propionic acid induce formation of hierarchical nanosphere morphologies whereas butyric acid promotes assembly of hollow spheres. The materials are active catalysts for CO oxidation. PMID:21655565

Ching, Stanton; Kriz, David A; Luthy, Kurt M; Njagi, Eric C; Suib, Steven L

2011-08-01

182

Nickel-doped cobalt ferrite nanoparticles: efficient catalysts for the reduction of nitroaromatic compounds and photo-oxidative degradation of toxic dyes.  

PubMed

This study deals with the exploration of NixCo1-xFe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) ferrite nanoparticles as catalysts for reduction of 4-nitrophenol and photo-oxidative degradation of Rhodamine B. The ferrite samples with uniform size distribution were synthesized using the reverse micelle technique. The structural investigation was performed using powder X-ray diffraction, high-resolution transmission electron microscopy, energy dispersive X-ray and scanning tunneling microscopy. The spherical particles with ordered cubic spinel structure were found to have the crystallite size of 4-6 nm. Diffused UV-visible reflectance spectroscopy was employed to investigate the optical properties of the synthesized ferrite nanoparticles. The surface area calculated using BET method was found to be highest for Co0.4Ni0.6Fe2O4 (154.02 m(2) g(-1)). Co0.4Ni0.6Fe2O4 showed the best catalytic activity for reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 as reducing agent, whereas CoFe2O4 was found to be catalytically inactive. The reduction reaction followed pseudo-first order kinetics. The effect of varying the concentration of catalyst and NaBH4 on the reaction rates was also scrutinized. The photo-oxidative degradation of Rhodamine B, enhanced oxidation efficacy was observed with the introduction of Ni(2+) in to the cobalt ferrite lattice due to octahedral site preference of Ni(2+). Almost 99% degradation was achieved in 20 min using NiFe2O4 nanoparticles as catalyst. PMID:24902783

Singh, Charanjit; Goyal, Ankita; Singhal, Sonal

2014-06-26

183

Influence of aging time of oleate precursor on the magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method  

NASA Astrophysics Data System (ADS)

Cobalt ferrite nanoparticles are of interest because of their room temperature coercivity and high magnetic anisotropy constant, which make them attractive in applications such as sensors based on the Brownian relaxation mechanism and probes to determine the mechanical properties of complex fluids at the nanoscale. These nanoparticles can be synthesized with a narrow size distribution by the thermal decomposition of an iron-cobalt oleate precursor in a high boiling point solvent. We studied the influence of aging time of the iron-cobalt oleate precursor on the structure, chemical composition, size, and magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method. The structure and thermal behavior of the iron-cobalt oleate was studied during the aging process. Infrared spectra indicated a shift in the coordination state of the oleate and iron/cobalt ions from bidentate to bridging coordination. Aging seemed to influence the thermal decomposition of the iron-cobalt oleate as determined from thermogravimmetric analysis and differential scanning calorimetry, where shifts in the temperatures corresponding to decomposition events and a narrowing of the endotherms associated with these events were observed. Aging promoted formation of the spinel crystal structure, as determined from X-ray diffraction, and influenced the nanoparticle magnetic properties, resulting in an increase in blocking temperature and magnetocrystalline anisotropy. Mossbauer spectra also indicated changes in the magnetic properties resulting from aging of the precursor oleate. Although all samples exhibited some degree of Brownian relaxation, as determined from complex susceptibility measurements in a liquid medium, aging of the iron-cobalt oleate precursor resulted in crossing of the in-phase ?'and out-of-phase ?? components of the complex susceptibility at the frequency of the Brownian magnetic relaxation peak, as expected for nanoparticles that relax through a single relaxation mechanism. The resulting nanoparticles would be suitable for sensors based on the Brownian relaxation mechanism and in determining mechanical properties of complex fluids at the size scale of the nanoparticles.

Herrera, Adriana P.; Polo-Corrales, Liliana; Chavez, Ermides; Cabarcas-Bolivar, Jari; Uwakweh, Oswald N. C.; Rinaldi, Carlos

2013-02-01

184

Synthesis and characterization of a novel extracellular biogenic manganese oxide (bixbyite-like Mn?O?) nanoparticle by isolated Acinetobacter sp.  

PubMed

Recently, manganese oxides have been considered in the environmental remediation, MRI diagnosis and drug and pharmaceutical industries. Different numbers of physicochemical and biological methods have been reported for the preparation of nanoscale manganese oxides. Although manganese oxide biogenesis by bacterial species has been recognized as the major Mn-oxidizing agent in nature, in this research, for first time, we demonstrated the process which used to produce bixbyite-like Mn(2)O(3) nanoparticles by isolated aerobic bacterium from Persian Gulf water. The 16SRNA sequencing showed that this isolate belong to a gram-negative Acinetobacter which produced nano Mn-oxide crystal particle. Characterization of complement morphology, size and chemical structure of these particles were determined by TEM, SEM, EDAX, XRD and FTIR. The data showed that this bacterium could produce nanosized extracellular bixbyite-like Mn(2)O(3) which depend on enzymatic pathway. PMID:21761221

Hosseinkhani, Baharak; Emtiazi, Giti

2011-09-01

185

The effect of annealing on phase evolution, microstructure and magnetic properties of Mn substituted CoFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese substituted CoFe2O4 nanoparticles has been prepared by a simple evaporation method and auto combustion method. The role of annealing temperature on phase, particle size and morphology of Mn-Co ferrite nanoparticles were determined by X-ray diffraction, and transmission electron microscopy (TEM). The lowest size of particles (~3 nm) is obtained by auto combustion method. The annealing effect creates a vital change in magnetic properties which is studied by using vibrating sample magnetometer (VSM). These spinel ferrites are decomposed to ?-Fe2O3 after annealing above 550 °C in air. However, ?-Fe2O3 phase was slowly vanished after ferrites annealing above 900 °C. The effect of this secondary phase on the structural and magnetic properties of Mn substituted cobalt ferrite nanoparticles is also discussed.

Ranjith Kumar, E.; Jayaprakash, R.; Prakash, T.

2014-05-01

186

Preparation of manganese doped cadmium sulfide nanoparticles in zincblende phase and their magnetic properties.  

PubMed

In this study, the random dope of Mn into CdS nanoparticles in zincblende phase has been carried out under the mild reaction condition. The resulting nanoparticles were characterized by energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), X-ray diffractometer (XRD), UV-Vis spectrometer, PL spectrometer, and SQUID. EDX showed that the compositions of Mn doped CdS nanoparticles were readily controlled. TEM showed the particle sizes were not significantly affected by the compositions, retaining to be ca. 3 nm with a narrow size distribution. UV-Vis and PL spectra of the resulting nanoparticles showed the intra-Mn level may be affected by the quantum size effect. SQUID measurement showed that the resulting nanoparticles showed diamagnetism, paramagnetism and superparamagnetism dependent on Mn content. PMID:23447951

Nakaya, Masafumi; Tanaka, Itaru; Muramatsu, Atsushi

2012-12-01

187

Solvothermal synthesis of cobalt ferrite nanoparticles loaded on multiwalled carbon nanotubes for magnetic resonance imaging and drug delivery.  

PubMed

Multiwalled carbon nanotube (MWCNT)/cobalt ferrite (CoFe(2)O(4)) magnetic hybrids were synthesized by a solvothermal method. The reaction temperature significantly affected the structure of the resultant MWCNT/CoFe(2)O(4) hybrids, which varied from 6nm CoFe(2)O(4) nanoparticles uniformly coated on the nanotubes at 180°C to agglomerated CoFe(2)O(4) spherical particles threaded by MWCNTs and forming necklace-like nanostructures at 240°C. Based on the superparamagnetic property at room temperature and high hydrophilicity, the MWCNT/CoFe(2)O(4) hybrids prepared at 180°C (MWCNT/CoFe(2)O(4)-180) were further investigated for biomedical applications, which showed a high T(2) relaxivity of 152.8 Fe mM(-1)s(-1) in aqueous solutions, a significant negative contrast enhancement effect on cancer cells and, more importantly, low cytotoxicity and negligible hemolytic activity. The anticancer drug doxorubicin (DOX) can be loaded onto the hybrids and subsequently released in a sustained and pH-responsive way. The DOX-loaded hybrids exhibited notable cytotoxicity to HeLa cancer cells due to the intracellular release of DOX. These results suggest that MWCNT/CoFe(2)O(4)-180 hybrids may be used as both effective magnetic resonance imaging contrast agents and anticancer drug delivery systems for simultaneous cancer diagnosis and chemotherapy. PMID:21664499

Wu, Huixia; Liu, Gang; Wang, Xue; Zhang, Jiamin; Chen, Yu; Shi, Jianlin; Yang, Hong; Hu, He; Yang, Shiping

2011-09-01

188

Structural and magnetic properties of dispersed nickel ferrite nanoparticles synthesized through thermal decomposition route  

NASA Astrophysics Data System (ADS)

Dispersed NiFe2O4 nanoparticles are synthesized through thermal decomposition of mixed-metal (Ni2+Fe3+)-oleate complex in the presence of high boiling point organic solvent 1-octadecene with oleic acid, by tuning the mixed-metal (Ni2+Fe3+)-oleate complex precursor and the temperature. Oleic acid is used as a surfactant, capped on the surface of the particles, which assists the particles to disperse in hexane. The as-synthesized NiFe2O4 nanoparticles have a cubic spinel structure as characterized by x-ray diffraction. The ferrimagnetic nature of these nanoparticles is conformed from the field dependent room temperature magnetization curves measured using vibrating sample magnetometer. The saturation magnetization of these nanoparticles strongly depends on the particle size which can be tuned by the mixed-metal (Ni2+Fe3+)-oleate complex precursor concentration and the synthesis temperature. Transmission electron microscope images show that the particles are nearly monodispersed at high synthesis temperature.

Behera, Bhaskar Chandra; Venkata, Ravindra A.; Srivastava, Chandan; Padhan, Prahallad

2013-02-01

189

Electron spin resonance studies on quantum tunneling in spinel ferrite nanoparticles  

Microsoft Academic Search

The electron spin resonance (ESR) spectrometer, a very sensitive instrument with fast detecting window to explore quantum phase transitions for magnetic nanoparticles, was exploited to study the fascinating interplay between thermal and quantum fluctuations in the vicinity of a quantum critical point. We have measured ESR in ferrofluid samples containing nanosize particles of Fe2O3. The evolution of the ESR spectrum

C. T. Hsieh; J. T. Lue

2003-01-01

190

Electron spin resonance studies on quantum tunneling in spinel ferrite nanoparticles  

Microsoft Academic Search

The electron spin resonance (ESR) spectrometer, a very sensitive instrument with fast detecting window to explore quantum phase transitions for magnetic nanoparticles, was exploited to study the fascinating interplay between thermal and quantum fluctuations in the vicinity of a quantum critical point. We have measured ESR in ferrofluid samples containing nanosize particles of Fe 2O 3. The evolution of the

Chang-Tsun Hsieh; Juh-Tzeng Lue

2003-01-01

191

Photocatalytic degradation of organic dyes with manganese-doped ZnO nanoparticles.  

PubMed

Manganese-doped and undoped ZnO photocatalysts were synthesized via wet-chemical techniques. Doping of ZnO with manganese (Mn(2+)) was intended to create tail states within the band gap of ZnO. These can subsequently be used as efficient photocatalysts which can effectively degrade organic contaminants only with visible light irradiation. Photocatalysts prepared with these techniques, which were characterized with transmission electron microscopy (TEM), infrared spectroscopy (FTIR), photo-co-relation spectroscopy (PCS) and UV-vis-spectroscopy showed significant difference in the optical absorption of Mn-doped ZnO. Enhancement in optical absorption of Mn-doped ZnO indicates that it can be used as an efficient photocatalyst under visible light irradiation. The photo-reduction activities of photocatalysts were evaluated using a basic aniline dye, methylene blue (MB) as organic contaminant irradiated only with visible light from tungsten bulb. It was found that manganese-doped ZnO (ZnO:Mn(2+)) bleaches MB much faster than undoped ZnO upon its exposure to the visible light. The experiment demonstrated that the photo-degradation efficiency of ZnO:Mn(2+) was significantly higher than that of undoped ZnO and might also be better than the conventional metal oxide semiconductor such as TiO(2) using MB as a contaminant. PMID:18221834

Ullah, Ruh; Dutta, Joydeep

2008-08-15

192

Luminol-silver nitrate chemiluminescence enhancement induced by cobalt ferrite nanoparticles.  

PubMed

CoFe(2)O(4) nanoparticles (NPs) could stimulate the weak chemiluminescence (CL) system of luminol and AgNO(3), resulting in a strong CL emission. The UV-visible spectra, X-ray photoelectron spectra and TEM images of the investigated system revealed that AgNO(3) was reduced by luminol to Ag in the presence of CoFe(2)O(4) NPs and the formed Ag covered the surface of CoFe(2)O(4) NPs, resulting in CoFe(2)O(4)-Ag core-shell nanoparticles. Investigation of the CL reaction kinetics demonstrated that the reaction among luminol, AgNO(3) and CoFe(2)O(4) NPs was fast at the beginning and slowed down later. The CL spectra of the luminol - AgNO(3) - CoFe(2)O(4) NPs system indicated that the luminophor was still an electronically excited 3-aminophthalate anion. A CL mechanism has been postulated. When the CoFe(2)O(4) NPs were injected into the mixture of luminol and AgNO(3), they catalyzed the reduction of AgNO(3) by luminol to produce luminol radicals and Ag, which immediately covered the CoFe(2)O(4) NPs to form CoFe(2)O(4)-Ag core-shell nanoparticles, and the luminol radicals reacted with the dissolved oxygen, leading to a strong CL emission. With the continuous deposition of Ag on the surface of CoFe(2)O(4) NPs, the catalytic activity of the core-shell nanoparticles was inhibited and a decrease in CL intensity was observed and also a slow growth of shell on the nanoparticles. PMID:21400653

Shi, Wenbing; Wang, Hui; Huang, Yuming

2011-01-01

193

Effect of annealing in a reductive environment on the magnetic properties of barium ferrite nanoparticles doped with Ti4+ and Co2+  

NASA Astrophysics Data System (ADS)

It was found experimentally that the annealing of BaFe10.6Co0.7Ti0.7O19 and BaFe10.2Co0.9Ti0.9O19 complex magnetic oxide nanoparticles in paraffin vapor irreversibly increases their coercive force H c and saturation magnetization M s to the H c and M s values for barium ferrite BaFe12O19. The annealing of these nanoparticles, and of particles of magnetic oxides CrO2, ?-Fe2O3, and BaFe12O19 in air and in paraffin vapor, has not been shown to affect their H c and M s values. An explanation in terms of diffusion self-purification of nanoparticles from ion impurities activated by chemical processes on their surface is offered.

Petinov, V. I.

2011-10-01

194

Effect of light on the magnetic properties of cobalt ferrite nanoparticles  

Microsoft Academic Search

We report variations in the coercivity of CoFe2O4 nanoparticles as a function of particle size, temperature and light intensity. For 30 nm particles, this change in was 2300 Oe at 10 K, 120 Oe at 170 K, for a light intensity of under 2 milliwatts. The remanent magnetization was nearly unchanged by illumination. A simple model of optical absorption followed

Anit K. Giri; Kelly Pellerin; Wanida Pongsaksawad; Monica Sorescu; Sara A. Majetich

2000-01-01

195

Synthesis of epoxy ferrite nanocomposites in supercritical carbon dioxide  

Microsoft Academic Search

A series of epoxy ferrite nanocomposites (EFNCs) was synthesised through dispersing ferrite nanoparticles (5.0 phr, parts per hundred of resin) into diglycidylether of bisphenol A (0.1 mol) in supercritical carbon dioxide at 85 ± 1°C, 1600 psi over 1 h followed by curing with triethylene tetramine (15 phr) at 40 ± 1°C. For this purpose, ferrite nanoparticles were synthesised through

M. G. H. Zaidi; P. L. Sah; S. Alam; A. K. Rai

2009-01-01

196

Silica-F127 nanohybrid-encapsulated manganese oxide nanoparticles for optimized T1 magnetic resonance relaxivity.  

PubMed

To properly engineer MnO nanoparticles (MONPs) of high r1 relaxivity, a nanohybrid coating consisting of silica and F127 (PEO106PPO70PEO106) is designed to encapsulate MONPs. Achieved by an interfacial templating scheme, the nanohybrid encapsulating layer is highly permeable and hydrophilic to allow for an optimal access of water molecules to the encapsulated manganese oxide core. Hence, the efficacy of MONPs as MRI contrast agents is significantly improved, as demonstrated by an enhancement of the MR signal measured with a pre-clinical 7.0 T MRI scanner. The nanohybrid encapsulation strategy also confers high colloidal stability to the hydrophobic MONPs by the surface decoration of PEO chains and a small overall diameter (<100 nm) of the PEO-SiO2 nanohybrid-encapsulated MONPs (PEOMSNs). The PEOMSNs are not susceptible to Mn-ion leaching, and their biocompatibility is affirmed by a low toxicity profile. Moreover, these hybrid nanocapsules exhibit a nano-rattle structure, which would favor the facile loading of various therapeutic reagents for theranostic applications. PMID:24193096

Wei Hsu, Benedict You; Wang, Miao; Zhang, Yu; Vijayaragavan, Vimalan; Wong, Siew Yee; Yuang-Chi Chang, Alex; Bhakoo, Kishore Kumar; Li, Xu; Wang, John

2014-01-01

197

Structural, optical, photocatalytic and antibacterial activity of zinc oxide and manganese doped zinc oxide nanoparticles  

Microsoft Academic Search

Polycrystalline ZnO doped with Mn (5 and 10at%) was prepared by the co-precipitation method. The effect of Mn doping on the photocatalytic, antibacterial activities and the influence of doping concentration on structural, optical properties of nanoparticles were studied. Structural and optical properties of the particles elucidated that the Mn2+ ions have substituted the Zn2+ ions without changing the Wurtzite structure

K. Rekha; M. Nirmala; Manjula G. Nair; A. Anukaliani

2010-01-01

198

Visualization of internalization of functionalized cobalt ferrite nanoparticles and their intracellular fate.  

PubMed

In recent years, nanoparticles (NPs) and related applications have become an intensive area of research, especially in the biotechnological and biomedical fields, with magnetic NPs being one of the promising tools for tumor treatment and as MRI-contrast enhancers. Several internalization and cytotoxicity studies have been performed, but there are still many unanswered questions concerning NP interactions with cells and NP stability. In this study, we prepared functionalized magnetic NPs coated with polyacrylic acid, which were stable in physiological conditions and which were also nontoxic short-term. Using fluorescence, scanning, and transmission electron microscopy, we were able to observe and determine the internalization pathways of polyacrylic acid-coated NPs in Chinese hamster ovary cells. With scanning electron microscopy we captured what might be the first step of NPs internalization - an endocytic vesicle in the process of formation enclosing NPs bound to the membrane. With fluorescence microscopy we observed that NP aggregates were rapidly internalized, in a time-dependent manner, via macropinocytosis and clathrin-mediated endocytosis. Inside the cytoplasm, aggregated NPs were found enclosed in acidified vesicles accumulated in the perinuclear region 1 hour after exposure, where they stayed for up to 24 hours. High intracellular loading of NPs in the Chinese hamster ovary cells was obtained after 24 hours, with no observable toxic effects. Thus polyacrylic acid-coated NPs have potential for use in biotechnological and biomedical applications. PMID:23486857

Bregar, Vladimir B; Lojk, Jasna; Suštar, Vid; Verani?, Peter; Pavlin, Mojca

2013-01-01

199

Visualization of internalization of functionalized cobalt ferrite nanoparticles and their intracellular fate  

PubMed Central

In recent years, nanoparticles (NPs) and related applications have become an intensive area of research, especially in the biotechnological and biomedical fields, with magnetic NPs being one of the promising tools for tumor treatment and as MRI-contrast enhancers. Several internalization and cytotoxicity studies have been performed, but there are still many unanswered questions concerning NP interactions with cells and NP stability. In this study, we prepared functionalized magnetic NPs coated with polyacrylic acid, which were stable in physiological conditions and which were also nontoxic short-term. Using fluorescence, scanning, and transmission electron microscopy, we were able to observe and determine the internalization pathways of polyacrylic acid–coated NPs in Chinese hamster ovary cells. With scanning electron microscopy we captured what might be the first step of NPs internalization – an endocytic vesicle in the process of formation enclosing NPs bound to the membrane. With fluorescence microscopy we observed that NP aggregates were rapidly internalized, in a time-dependent manner, via macropinocytosis and clathrin-mediated endocytosis. Inside the cytoplasm, aggregated NPs were found enclosed in acidified vesicles accumulated in the perinuclear region 1 hour after exposure, where they stayed for up to 24 hours. High intracellular loading of NPs in the Chinese hamster ovary cells was obtained after 24 hours, with no observable toxic effects. Thus polyacrylic acid–coated NPs have potential for use in biotechnological and biomedical applications.

Bregar, Vladimir B; Lojk, Jasna; Sustar, Vid; Veranic, Peter; Pavlin, Mojca

2013-01-01

200

Effects of pH and citric acid content on the structure and magnetic properties of MnZn ferrite nanoparticles synthesized by a sol-gel autocombustion method  

NASA Astrophysics Data System (ADS)

MnZn ferrite nanoparticles have been synthesized by a sol-gel autocombustion technique with different pHs of 0, 5 and 7 and different citric acid to metal nitrate (CA/MN) molar ratios of 0.25, 0.5 and 1. The crystallite size, microstructure and magnetic properties were studied using X-ray diffraction, scanning electron microscopy and vibrating sample magnetometry methods. The results showed that the single phase MnZn ferrite could be achieved directly without any post-calcination using pH of 7 and CA/MN molar ratio of 0.5. MnZn ferrite nanoparticles prepared by pH=7 and CA/MN=0.5 with the crystallite size of 39 nm exhibited saturation magnetization of 20.9 emu/g and coercivity of 44 Oe.

Seyyed Ebrahimi, S. A.; Masoudpanah, S. M.

2014-05-01

201

Iron(III) and manganese(II) substituted hydroxyapatite nanoparticles: Characterization and cytotoxicity analysis  

NASA Astrophysics Data System (ADS)

Calcium hydroxyapatite (HA) is the main inorganic component of natural bones and can bond to bone directly in vivo. Thus HA is widely used as coating material on bone implants due to its good osteoconductivity and osteoinductivity. Metal ions doped HA have been used as catalyst or absorbents since the ion exchange method has introduced new properties in HA which are inherent to the metal ions. For example, Mn2+ ions have the potential to increase cell adhesion while Fe3+ ions have magnetic properties. Here, Fe(III) substituted hydroxyapatite (Fe-HA) and Mn(II) substituted hydroxyapatite (Mn-HA) were produced by wet chemical method coupled with ion exchange mechanism. Compared with pure HA, the colour of both Fe-HA and Mn-HA nanoparticles changed from white to brown and pink respectively. The intensity of the colours increased with increasing substitution concentrations. XRD patterns showed that all samples were single phased HA while the FTIR spectra revealed all samples possessed the characteristic phosphate and hydroxyl adsorption bands of HA. However, undesired adsorption bands of carbonate substitution (B-type carbonated HA) and H2O were also detected, which was reasonable since the wet chemical method was used in the synthesis of these nanoparticles. FESEM images showed all samples were elongated spheroids with small size distribution and of around 70 nm, regardless of metal ion substitution concentrations. EDX spectra showed the presence of Fe and Mn and ICP-AES results revealed all metal ion substituted HA were non-stoichiometric (Ca/P atomic ratio deviates from 1.67). Fe-HA nanoparticles were paramagnetic and the magnetic susceptibility increased with the increase of Fe content. Based on the extraction assay for cytotoxicity test, both Fe-HA and Mn-HA displayed non-cytotoxicity to osteoblast.

Li, Yan; Teck Nam, Chai; Ooi, Chui Ping

2009-09-01

202

Semi-empirical study of ortho-cresol photo degradation in manganese-doped zinc oxide nanoparticles suspensions  

PubMed Central

The optimization processes of photo degradation are complicated and expensive when it is performed with traditional methods such as one variable at a time. In this research, the condition of ortho-cresol (o-cresol) photo degradation was optimized by using a semi empirical method. First of all, the experiments were designed with four effective factors including irradiation time, pH, photo catalyst’s amount, o-cresol concentration and photo degradation % as response by response surface methodology (RSM). The RSM used central composite design (CCD) method consists of 30 runs to obtain the actual responses. The actual responses were fitted with the second order algebraic polynomial equation to select a model (suggested model). The suggested model was validated by a few numbers of excellent statistical evidences in analysis of variance (ANOVA). The used evidences include high F-value (143.12), very low P-value (<0.0001), non-significant lack of fit, the determination coefficient (R2?=?0.99) and the adequate precision (47.067). To visualize the optimum, the validated model simulated the condition of variables and response (photo degradation %) be using a few number of three dimensional plots (3D). To confirm the model, the optimums were performed in laboratory. The results of performed experiments were quite close to the predicted values. In conclusion, the study indicated that the model is successful to simulate the optimum condition of o-cresol photo degradation under visible-light irradiation by manganese doped ZnO nanoparticles.

2012-01-01

203

Seebeck Coefficient of Manganese Oxide Nanoparticles as a Function of Ohmic Resistance  

NASA Astrophysics Data System (ADS)

Due to the ever increasing energy demand and growing global concern over the environmental impact of CO2 emissions, there is an urging need to seek solutions to transit from fossil fuels to sustainable energy. Thermoelectric (TE) materials show great promise for converting waste heat energy into electricity. TE systems have many unique advantages such as silent operationality, time reliability, and dimensional scalability. Most recently, researchers Song et al. [1] found that MnO2 nanoparticles show a giant Seebeck coefficient of S = 20 mV/K, which is100 times higher than bismuth telluride, one of the best TE materials. Song et al.[1] concluded the paper claiming that the giant S is related to the surface density of the electronic states (DOS). However, they provided very little information about the S as a function of Ohmic resistance [R] for different nano particle sizes which can give information about the DOS. Our preliminary results show that there is a sudden increase of S from 0.33-0.63 mV/K as R increases from 80-110 Ohms. This transition has never been seen before and it can give clues as to the existence of the Giant S observed in this material.[4pt] [1] F. Song, L. Wu and S. Liang, Giant Seebeck coefficient thermoelectric device of MnO2 powder, Nano. 23, 085401 (2012).

Francis, Nicholas; Hedden, Morgan; Constantin, Costel

2013-03-01

204

Ultrahigh relaxivity and safe probes of manganese oxide nanoparticles for in vivo imaging  

PubMed Central

Mn-based nanoparticles (NPs) have emerged as new class of probes for magnetic resonance imaging due to the impressive contrast ability. However, the reported Mn-based NPs possess low relaxivity and there are no immunotoxicity data regarding Mn-based NPs as contrast agents. Here, we demonstrate the ultrahigh relaxivity of water protons of 8.26?mM?1s?1 from the Mn3O4 NPs synthesized by a simple and green technique, which is twice higher than that of commercial gadolinium (Gd)-based contrast agents (4.11?mM?1s?1) and the highest value reported to date for Mn-based NPs. We for the first time demonstrate these Mn3O4 NPs biocompatibilities both in vitro and in vivo are satisfactory based on systematical studies of the intrinsic toxicity including cell viability of human nasopharyngeal carcinoma cells, normal nasopharyngeal epithelium, apoptosis in cells and in vivo immunotoxicity. These findings pave the way for the practical clinical diagnosis of Mn based NPs as safe probes for in vivo imaging.

Xiao, J.; Tian, X. M.; Yang, C.; Liu, P.; Luo, N. Q.; Liang, Y.; Li, H. B.; Chen, D. H.; Wang, C. X.; Li, L.; Yang, G. W.

2013-01-01

205

Ultrahigh relaxivity and safe probes of manganese oxide nanoparticles for in vivo imaging  

NASA Astrophysics Data System (ADS)

Mn-based nanoparticles (NPs) have emerged as new class of probes for magnetic resonance imaging due to the impressive contrast ability. However, the reported Mn-based NPs possess low relaxivity and there are no immunotoxicity data regarding Mn-based NPs as contrast agents. Here, we demonstrate the ultrahigh relaxivity of water protons of 8.26 mM-1s-1 from the Mn3O4 NPs synthesized by a simple and green technique, which is twice higher than that of commercial gadolinium (Gd)-based contrast agents (4.11 mM-1s-1) and the highest value reported to date for Mn-based NPs. We for the first time demonstrate these Mn3O4 NPs biocompatibilities both in vitro and in vivo are satisfactory based on systematical studies of the intrinsic toxicity including cell viability of human nasopharyngeal carcinoma cells, normal nasopharyngeal epithelium, apoptosis in cells and in vivo immunotoxicity. These findings pave the way for the practical clinical diagnosis of Mn based NPs as safe probes for in vivo imaging.

Xiao, J.; Tian, X. M.; Yang, C.; Liu, P.; Luo, N. Q.; Liang, Y.; Li, H. B.; Chen, D. H.; Wang, C. X.; Li, L.; Yang, G. W.

2013-12-01

206

Control of Particle Size and Morphology of Cobalt-Ferrite Nanoparticles by Salt-Matrix during Annealing  

NASA Astrophysics Data System (ADS)

Salt-matrix annealing of mechanically alloyed Co-ferrite nanopowder was used to modify its particle size and morphology. Efficiency improvement due to suppression of sintering and growth resulted in reduction of average particle size from 100nm for salt-less to 40nm for salt-full annealing procedure. Nanosized single-phase cobalt-ferrite particles were observed after 2h annealing at 750°C in the samples milled for 20 hours both with and without NaCl. NaCl:CoFe2O4 ratio of 10:1 resulted in cabbage-like clusters containing particles smaller than 50 nm.

Azizi, A.; Sadrnezhaad, S. K.; Mostafavi, M.

207

Superparamagnetic relaxation evidences large surface contribution for the magnetic anisotropy of MnFe 2 0 4 nanoparticles of ferrofluids  

Microsoft Academic Search

Manganese ferrite nanoparticles, in the size range 3.3–9.0 nm, are prepared by a hydrothermal coprecipitation process and\\u000a peptized in aqueous solution. The magnetization curves recorded at room temperature on diluted colloidal sols allow characterizing\\u000a the distribution of magnetic moment by using a simple Langevin formalism. Mssbauer spectroscopy measurements performed on\\u000a powder samples at 77 K exhibit a quadrupolar doublet which intensity

C. R. Alves; Renata Aquino; Jérôme Depeyrot; Francisco A. Tourinho; Emmanuelle Dubois; Régine Perzynski

2007-01-01

208

Structural, electrical, magnetic and dielectric properties of rare-earth substituted cobalt ferrites nanoparticles synthesized by the co-precipitation method  

NASA Astrophysics Data System (ADS)

Pure nanoparticles of the rare-earth substituted cobalt ferrites CoRExFe2-xO4 (where RE=Nd, Sm and Gd and x=0.1 and 0.2) were prepared by the chemical co-precipitation method. X-ray diffraction, Transmission electron microscopy (TEM), d.c. electrical conductivity, Magnetic hysteresis and Thermal analysis are utilized in order to study the effect of variation in the rare-earth substitution and its impact on particle size, magnetic properties like MS, HC and Curie temperature. The phase identification of the materials by X-ray diffraction reveals the single-phase nature of the materials. The lattice parameter increased with rare-earth content for x?0.2. The Transmission electron micrographs of Nd-, Sm- and Gd-substituted CoFe2O4 exhibit the particle size 36.1 to 67.8 nm ranges. The data of temperature variation of the direct current electrical conductivity showed definite breaks, which corresponds to ferrimagnetic to paramagnetic transitions. The thermoelectric power for all compound are positive over the whole range of temperature. The dielectric constant decreases with frequency and rare-earth content for the prepared samples. The magnetic properties of rare-earth substituted cobalt ferrites showed a definite hysteresis loop at room temperature. The reduction of coercive force, saturation magnetization, ratio MR/MS and magnetic moments may be due to dilution of the magnetic interaction.

Nikumbh, A. K.; Pawar, R. A.; Nighot, D. V.; Gugale, G. S.; Sangale, M. D.; Khanvilkar, M. B.; Nagawade, A. V.

2014-04-01

209

A note on the elastic moduli of ferrites at low temperatures  

Microsoft Academic Search

The elastic moduli of polycrystalline nickel-zinc and manganese-zinc ferrites have been studied in the temperature range 80-303°K, using the composite piezoelectric oscillator method. The elastic moduli E and G of nickel-zinc ferrite are found to increase with decreasing temperature, whilst those of manganese-zinc ferrite decrease with decreasing temperature down to about 257°K and increase below this temperature.

B P Nagi Reddy

1968-01-01

210

Hot coal gas desulfurization with manganese-based sorbents.  

National Technical Information Service (NTIS)

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-...

M. T. Hepworth R. Ben-Slimane

1994-01-01

211

Physical and magnetic properties of highly aluminum doped strontium ferrite nanoparticles prepared by auto-combustion route  

NASA Astrophysics Data System (ADS)

Highly Al3+ ion doped nanocrystalline SrFe12-xAlxO19 (0?x?12), were prepared by the auto-combustion method and heat treated in air at 1100 °C for 12 h. The phase identification of the powders performed using x-ray diffraction show presence of high-purity hexaferrite phase and absence of any secondary phases. With Al3+ doping, the lattice parameters decrease due to smaller Al3+ ion replacing Fe3+ ions. Morphological analysis performed using transmission electron microscope show growth of needle shaped ferrites with high aspect ratio at Al3+ ion content exceeding x?2. Al3+ substitution modifies saturation magnetization (MS) and coercivity (HC). The room temperature MS values continuously reduced while HC value increased to a maximum value of 18,100 Oe at x=4, which is an unprecedented increase (˜321%) in the coercivity as compared to pure Sr-Ferrite. However, at higher Al3+ content x>4, a decline in magnetization and coercivity has been observed. The magnetic results indicate that the best results for applications of this ferrite will be obtained with an iron deficiency in the stoichiometric formulation.

Luo, H.; Rai, B. K.; Mishra, S. R.; Nguyen, V. V.; Liu, J. P.

2012-08-01

212

Hot coal gas desulfurization with manganese-based sorbents  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E.T. Turkdogan indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}/O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese higher temperatures than zinc ferrite or zinc titanate. This presentation gives the thermodynamic background for consideration of manganese-based sorbents as an alternative to zinc ferrite. To date the work which has been in progress for nine months is limited at this stage to thermogravimetric testing of four formulations of manganese-alumina sorbents to determine the optimum conditions of pelletization and induration to produce reactive pellets.

Lynch, D.; Hepworth, M.T.

1993-09-01

213

Preparation, characterization, in vivo and in vitro studies of arsenic trioxide Mg-Fe ferrite magnetic nanoparticles  

Microsoft Academic Search

Aim:MgFe2O4 magnetic nanoparticle composed of As2O3 (As2O3-MNPs) were prepared and their in vitro and in vivo characteristics were studied.Methods:The solvent-displacement method was applied for preparation of the nanoparticle using Poly-D,L-lactic-co-glycolic acid(PLGA). The characteristics studies of the products included magnetic response, morphology (transmission electron microscopy and scanning electron microscopy), entrapment efficiency, drug loading, particle sizes, zeta potential, in vitro drug release

Guo-fu Yang; Xiang-hui Li; Zhe Zhao; Wen-bo Wang; Wen-bo Wang

2009-01-01

214

Copper(0) nanoparticles supported on silica-coated cobalt ferrite magnetic particles: cost effective catalyst in the hydrolysis of ammonia-borane with an exceptional reusability performance.  

PubMed

Herein we report the development of a new and cost-effective nanocomposite catalyst for the hydrolysis of ammonia-borane (NH(3)BH(3)), which is considered to be one of the most promising solid hydrogen carriers because of its high gravimetric hydrogen storage capacity (19.6% wt) and low molecular weight. The new catalyst system consisting of copper nanoparticles supported on magnetic SiO(2)/CoFe(2)O(4) particles was reproducibly prepared by wet-impregnation of Cu(II) ions on SiO(2)/CoFe(2)O(4) followed by in situ reduction of the Cu(II) ions on the surface of magnetic support during the hydrolysis of NH(3)BH(3) and characterized by ICP-MS, XRD, XPS, TEM, HR-TEM and N(2) adsorption-desorption technique. Copper nanoparticles supported on silica coated cobalt(II) ferrite SiO(2)/CoFe(2)O(4) (CuNPs@SCF) act as highly active catalyst in the hydrolysis of ammonia-borane, providing an initial turnover frequency of TOF = 2400 h(-1) at room temperature, which is not only higher than all the non-noble metal catalysts but also higher than the majority of the noble metal based homogeneous and heterogeneous catalysts employed in the same reaction. More importantly, they were easily recovered by using a permanent magnet in the reactor wall and reused for up to 10 recycles without losing their inherent catalytic activity significantly, which demonstrates the exceptional reusability of the CuNPs@SCF catalyst. PMID:22856878

Kaya, Murat; Zahmakiran, Mehmet; Ozkar, Saim; Volkan, Mürvet

2012-08-01

215

NMR-D study of the local spin dynamics and magnetic anisotropy in different nearly monodispersed ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

We present a systematic experimental comparison of the superparamagnetic relaxation time constants obtained by means of dynamic magnetic measurements and 1H-NMR relaxometry, on ferrite-based nanosystems with different composition, various core sizes and dispersed in different solvents. The application of a heuristic model for the relaxivity allowed a comparison between the reversal time of magnetization as seen by NMR and the results from the AC susceptibility experiments, and an estimation of fundamental microscopic properties. A good agreement between the NMR and AC results was found when fitting the AC data to a Vogel-Fulcher law. Key parameters obtained from the model have been exploited to evaluate the impact of the contribution from magnetic anisotropy to the relaxivity curves and estimate the minimum approach distance of the bulk solvent.

Bordonali, L.; Kalaivani, T.; Sabareesh, K. P. V.; Innocenti, C.; Fantechi, E.; Sangregorio, C.; Casula, M. F.; Lartigue, L.; Larionova, J.; Guari, Y.; Corti, M.; Arosio, P.; Lascialfari, A.

2013-02-01

216

Hot coal gas desulfurization with manganese-based sorbents  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This annual topical report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite.

Hepworth, M.T.; Ben-Slimane, R.

1994-12-01

217

Enrichment of magnetic alignment stimulated by {gamma}-radiation in core-shell type nanoparticle Mn-Zn ferrite  

SciTech Connect

Core shell type nanoparticle Mn{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} systems with x=0.55, 0.65 and 0.75 were prepared using autocombustion method. The systems were characterized using tools like XRD and IR for structure confirmation. Magnetic parameter measurements like Saturation magnetization and coercivity were obtained from hysteresis loop which exhibited a symmetry shift due to core shell nature of the nanoparticles. Nanoparticles of particle size between 21.2nm to 25.7nm were found to show 20 percent shrinkage after being radiated by the {gamma}-radiation. This is due to variation in the cation distribution which also affects the cell volume of the cubic cell. Lattice constant reduction observed is reflected in the magnetic properties of the samples. A considerable hike in the saturation magnetization of the samples was observed due to enrichment of magnetic alignment in the magnetic core of the particles. Samples under investigation were irradiated with gamma radiation from Co{sup 60} source for different time intervals.

Naik, P. P.; Tangsali, R. B. [Department of Physics, Goa University, Taleigao Plateau, Goa-403206 (India); Sonaye, B.; Sugur, S. [Goa Medical College, Bambolim, Goa (India)

2013-02-05

218

Structural, optical, and magnetic studies of manganese-doped zinc oxide hierarchical microspheres by self-assembly of nanoparticles  

PubMed Central

In this study, a series of manganese [Mn]-doped zinc oxide [ZnO] hierarchical microspheres [HMSs] are prepared by hydrothermal method only using zinc acetate and manganese acetate as precursors and ethylene glycol as solvent. X-ray diffraction indicates that all of the as-obtained samples including the highest Mn (7 mol%) in the crystal lattice of ZnO have a pure phase (hexagonal wurtzite structure). A broad Raman spectrum from as-synthesized doping samples ranges from 500 to 600 cm-1, revealing the successful doping of paramagnetic Mn2+ ions in the host ZnO. Optical absorption analysis of the samples exhibits a blueshift in the absorption band edge with increasing dopant concentration, and corresponding photoluminescence spectra show that Mn doping suppresses both near-band edge UV emission and defect-related blue emission. In particular, magnetic measurements confirm robust room-temperature ferromagnetic behavior with a high Curie temperature exceeding 400 K, signifying that the as-formed Mn-doped ZnO HMSs will have immense potential in spintronic devices and spin-based electronic technologies.

2012-01-01

219

Light-induced covalent immobilization of monolayers of magnetic nanoparticles on hydrogen-terminated silicon.  

PubMed

Specifically tailored ?-alkenyl-1-carboxylic acids were synthesized for use as surfactants in the single-step preparation of manganese ferrite (MnFe2O4) nanoparticles (NPs). Monodisperse manganese ferrite NPs terminated with ?-alkenyl moieties were prepared via a one-pot reaction at high temperature without the need of ligand exchange. Using this approach, simple adjustment of the rate of heating allowed precise tuning of the size of the nanoparticles, which were characterized in bulk form by transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD). These surfactant-coated magnetic nanoparticles were then deposited onto hydrogen-terminated silicon(111) wafers and covalently anchored to the surface by UV-initiated covalent bonding. Analysis by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) confirmed that the UV treatment led to covalent immobilization of the NPs on the silicon surface with a consistent packing density across the surface. The magnetic properties of the stable, surface-bound nanoparticle arrays were characterized using a superconducting quantum interference device (SQUID) magnetometer. The materials and methods described here are being developed for use in bit-patterned ultrahigh density magnetic recording media and nanoscale biomagnetic sensing. PMID:20857939

Leem, Gyu; Zhang, Shishan; Jamison, Andrew C; Galstyan, Eduard; Rusakova, Irene; Lorenz, Bernd; Litvinov, Dmitri; Lee, T Randall

2010-10-01

220

Synthesis and magnetic properties of the size-controlled Mn–Zn ferrite nanoparticles by oxidation method  

Microsoft Academic Search

Size-controlled Mn0.67Zn0.33Fe2O4 nanoparticles in the wide range from 80 to 20nm have been synthesized, for the first time, using the oxidation method. It has been demonstrated that the particle size can be tailor-made by varying the concentration of the oxidant. The magnetization of the 80nm particles was 49Am2kg?1 compared to 34Am2kg?1 for the 20nm particles. The Curie temperatures for all

R. Justin Joseyphus; A. Narayanasamy; K. Shinoda; B. Jeyadevan; K. Tohji

2006-01-01

221

Magnetic and optical properties of manganese doped ZnO nanoparticles synthesized by sol-gel technique  

NASA Astrophysics Data System (ADS)

Mn doped ZnO nanoparticles with different doping concentration (1, 2, 3, 4, 5 at.%) were prepared by sol-gel method using supercritical drying conditions of ethyl alcohol. The structural, morphological, optical and magnetic properties of the as-prepared nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV measurements and superconducting quantum interference device (SQUID). The structural properties showed that the undoped and Mn doped ZnO nanoparticles exhibit hexagonal wurtzite structure. From the optical studies, the transmittance in UV region was decreased with the increase of Mn concentration. For Mn doped ZnO nanoparticles the optical band gap varies between 3.34 eV and 3.22 eV. It was found that the doping Mn2+ ions have a significant influence on the optical properties. The magnetic characterization of the samples with 1% and 5% Mn concentrations reveal diamagnetic behavior for the first one and the presence of both paramagnetic and ferromagnetic behavior for the second. The room ferromagnetic component is due to the presence of the secondary phase ZnOMn3 which is confirmed by XRD study.

Omri, K.; El Ghoul, J.; Lemine, O. M.; Bououdina, M.; Zhang, B.; El Mir, L.

2013-08-01

222

High resolution electron energy loss spectroscopy of manganese oxides: Application to Mn{sub 3}O{sub 4} nanoparticles  

SciTech Connect

Manganese oxides particularly Mn{sub 3}O{sub 4} Hausmannite are currently used in many industrial applications such as catalysis, magnetism, electrochemistry or air contamination. The downsizing of the particle size of such material permits an improvement of its intrinsic properties and a consequent increase in its performances compared to a classical micron-sized material. Here, we report a novel synthesis of hydrophilic nano-sized Mn{sub 3}O{sub 4}, a bivalent oxide, for which a precise characterization is necessary and for which the determination of the valency proves to be essential. X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and particularly High Resolution Electron Energy Loss Spectroscopy (HREELS) allow us to perform these measurements on the nanometer scale. Well crystallized 10-20 nm sized Mn{sub 3}O{sub 4} particles with sphere-shaped morphology were thus successfully synthesized. Meticulous EELS investigations allowed the determination of a Mn{sup 3+}/Mn{sup 2+} ratio of 1.5, i.e. slightly lower than the theoretical value of 2 for the bulk Hausmannite manganese oxide. This result emphasizes the presence of vacancies on the tetrahedral sites in the structure of the as-synthesized nanomaterial. - Research Highlights: {yields}Mn{sub 3}O{sub 4} bulk and nano were studied by XRD, TEM and EELS. {yields}XRD and TEM determine the degree of crystallinity and the narrow grain size. {yields}HREELS gave access to the Mn{sup 3+}/Mn{sup 2+} ratio. {yields}Mn{sub 3}O{sub 4} nano have vacancies on the tetrahedral sites.

Laffont, L., E-mail: Lydia.laffont@ensiacet.fr [Institut Carnot, Laboratoire CIRIMAT (equipe MEMO), CNRS UMR 5085, ENSIACET, 4 allee Emile Monso, BP 74233, 31432 Toulouse cedex 4 (France); Gibot, P. [Laboratoire de Reactivite et Chimie des Solides CNRS UMR 6007, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens cedex 9 (France)

2010-11-15

223

Influence of plastic deformation on the properties of ferritic corrosion-resistant steels  

Microsoft Academic Search

1.Ferritic corrosion-resistant steels are characterized by differing instability of the a-solid solution in cold reduction depending upon the silicon, manganese, and chromium contents. With a 15% Cr content in the steel to obtain a ferritic structure stable in reduction it is necessary to add up to 1.5% Si to it. An increase in manganese content to more than 1% leads

N. A. Sorokina; N. V. Andrushova; V. I. Gal'tsova; I. I. Kaputkin

1991-01-01

224

In situ synthesis of cobalt ferrite nanoparticle/polymer hybrid from a mixed Fe-Co methacrylate for magnetic hyperthermia  

NASA Astrophysics Data System (ADS)

Hyperthermic CoFe2O4 nanoparticle (CFO NP)/polymer hybrids were synthesized by hydrolysis-condensation from a complex of Co and Fe possessing methacrylate ligands. Single-crystal analysis revealed that the complex consisted of two Co and four Fe metal atoms coordinated by methacrylate and 2-methoxyethoxy groups. The complex was copolymerized with 2-hydroxyethyl methacrylate (HEMA) and the resulting copolymer was then hydrolyzed to form a CFO NP/copolymer of poly(methacrylate) and poly(2-hydroxyethyl methacrylate) hybrid. Copolymerization with HEMA enhanced the stability of the hybrid in water. The size and magnetic properties of CFO in the hybrid were controlled by adjusting the hydrolysis conditions. Moreover, the hybrid generated heat under an alternating current magnetic field; its exothermal properties depended on the magnetic properties of the hybrid, the strength of the applied field, and the CFO NP content in the agar phantom matrix.

Hayashi, Koichiro; Maeda, Kazuki; Moriya, Makoto; Sakamoto, Wataru; Yogo, Toshinobu

2012-09-01

225

Cobalt ferrite based magnetostrictive materials for magnetic stress sensor and actuator applications  

NASA Technical Reports Server (NTRS)

Magnetostrictive material based on cobalt ferrite is described. The cobalt ferrite is substituted with transition metals (such manganese (Mn), chromium (Cr), zinc (Zn) and copper (Cu) or mixtures thereof) by substituting the transition metals for iron or cobalt to form substituted cobalt ferrite that provides mechanical properties that make the substituted cobalt ferrite material effective for use as sensors and actuators. The substitution of transition metals lowers the Curie temperature of the material (as compared to cobalt ferrite) while maintaining a suitable magnetostriction for stress sensing applications.

Jiles, David C. (Inventor); Paulsen, Jason A. (Inventor); Snyder, John E. (Inventor); Lo, Chester C. H. (Inventor); Ring, Andrew P. (Inventor); Bormann, Keith A. (Inventor)

2008-01-01

226

Elastic moduli of some ferrites at low temperatures  

Microsoft Academic Search

Elastic moduli of nickel-zinc (two different compositions), manganese—zinc and barium ferrites were determined as a function of temperature from 80 to 303 K. The experimental method employed was the composite piezo-electric oscillator capable of measuring elastic wave velocities to a few parts in 10. The elastic moduli of nickel-zinc ferrites were found to increase with decrease in temperature almost linearly

B. P. N. Reddy; P. J. Reddy

1974-01-01

227

Synthesis and characterization of carboxymethyl dextran-coated Mn/Zn ferrite for biomedical applications  

NASA Astrophysics Data System (ADS)

Previous studies have shown that magnetic nanoparticles possess great potential for various in vivo applications such as magnetic resonance imaging contrast enhancement, tissue repair, cancer treatment agents, and controlled drug delivery. Many of these applications require that magnetic nanoparticles be colloidally stable in biological media. The goal of this study was to obtain a magnetic fluid produced by the colloidal suspension of manganese/zinc ferrite (MZF) nanoparticles that could be stably dispersed in aqueous solution throughout the range of physiological pH and ionic strength. These superparamagnetic nanoparticles were stabilized through steric repulsion by coating with biologically compatible carboxymethyl dextran (CMDx). Samples of the resultant magnetic fluid were analyzed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), X-ray diffraction (XRD), zeta potential measurements, dynamic light scattering, transmission electron microscopy (TEM), and SQUID magnetometry. Results show that we obtained superparamagnetic metal-oxide crystals with composition of Mn 0.24Zn 0.76Fe 2O 4. Cell viability measurements show the material is non-toxic to MCF-7 and CaCo-2 cell lines at concentrations of up to 7.5 mg/mL of particle fraction for contact time of up to 48 h.

Latorre-Esteves, Magda; Cortés, Angel; Torres-Lugo, Madeline; Rinaldi, Carlos

2009-10-01

228

A smart platform for hyperthermia application in cancer treatment: cobalt-doped ferrite nanoparticles mineralized in human ferritin cages.  

PubMed

Magnetic nanoparticles, MNPs, mineralized within a human ferritin protein cage, HFt, can represent an appealing platform to realize smart therapeutic agents for cancer treatment by drug delivery and magnetic fluid hyperthermia, MFH. However, the constraint imposed by the inner diameter of the protein shell (ca. 8 nm) prevents its use as heat mediator in MFH when the MNPs comprise pure iron oxide. In this contribution, we demonstrate how this limitation can be overcome through the controlled doping of the core with small amount of Co(II). Highly monodisperse doped iron oxide NPs with average size of 7 nm are mineralized inside a genetically modified variant of HFt, carrying several copies of ?-melanocyte-stimulating hormone peptide, which has already been demonstrated to have excellent targeting properties toward melanoma cells. HFt is also conjugated to poly(ethylene glycol) molecules to increase its in vivo stability. The investigation of hyperthermic properties of HFt-NPs shows that a Co doping of 5% is enough to strongly enhance the magnetic anisotropy and thus the hyperthermic efficiency with respect to the undoped sample. In vitro tests performed on B16 melanoma cell line demonstrate a strong reduction of the cell viability after treatment with Co doped HFt-NPs and exposure to the alternating magnetic field. Clear indications of an advanced stage of apoptotic process is also observed from immunocytochemistry analysis. The obtained data suggest this system represents a promising candidate for the development of a protein-based theranostic nanoplatform. PMID:24689973

Fantechi, Elvira; Innocenti, Claudia; Zanardelli, Matteo; Fittipaldi, Maria; Falvo, Elisabetta; Carbo, Miriam; Shullani, Valbona; Di Cesare Mannelli, Lorenzo; Ghelardini, Carla; Ferretti, Anna Maria; Ponti, Alessandro; Sangregorio, Claudio; Ceci, Pierpaolo

2014-05-27

229

Electronic structure and magnetic properties of the Ni0.2Cd0.3Fe(2.5-x)A1(x)O4 (0 < or = x < or = 0.4) ferrite nanoparticles.  

PubMed

The structural, magnetic, and electronic structural properties of Ni0.2Cd0.3Fe(2.5-x)Al(x)O4 ferrite nanoparticles were studied via X-ray diffraction (XRD), transmission electron microscopy (TEM), DC magnetization, and near-edge X-ray absorption fine-structure spectroscopy (NEXAFS) measurements. Nanoparticles of Ni0.2Cd0.3Fe(2.5x)Al(x)O4 (0 < or = x < or = 0.4) ferrite were synthesized using the sol-gel method. The XRD and TEM measurements showed that all the samples had a single-phase nature with a cubic structure, and had nanocrystalline behavior. From the XRD and TEM analysis, it was found that the particle size increases with Al doping. The DC magnetization measurements revealed that the blocking temperature increases with increased Al doping. It was observed that the magnetic moment decreases with Al doping, which may be due to the dilution of the sublattice by the doping of the Al ions. The NEXAFS measurements performed at room temperature indicated that Fe exists in a mixed-valence state. PMID:21446463

Kumar, Shalendra; Batoo, Khalid Mujasam; Gautam, S; Koo, B H; Alimuddin; Chae, K H; Chung, Hanshik; Lee, Chan Gyu

2011-01-01

230

Comparative study of NiFe{sub 2?x}Al{sub x}O{sub 4} ferrite nanoparticles synthesized by chemical co-precipitation and sol–gel combustion techniques  

SciTech Connect

Graphical abstract: AFM images of NiFe{sub 2}O{sub 4} ferrite nanoparticles at room temperature synthesized by sol–gel technique. Highlights: ? Particle size reduces to less than 30 nm. ? DC electrical resistivity increases with substitution of Cr{sup 3+}. ? Dielectric constant decreases. -- Abstract: A series of aluminum substituted Ni-ferrite nanoparticles have been synthesized by chemical co-precipitation and sol–gel techniques. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), DC electrical resistivity and dielectric properties. Analysis of the X-ray diffraction pattern of all the samples confirmed the formation of spinel structure. The crystallite sizes remain within the range 25–41 ± 3 nm. FTIR measurements show two fundamental absorption bands, assigned to the vibration of tetrahedral and octahedral sites. DC electrical resistivity increases from 6.60 × 10{sup 7} to 6.9 × 10{sup 10} ? cm as the Al{sup 3+} concentration increases from 0.00 to 0.50. The dielectric constant and loss tangent decreases with increasing Al{sup 3+} concentration from 22 to 14, 0.354 to 0.27 respectively at 5 MHz for all the samples. Impedance measurements as a function of frequency (1 kHz–5 MHz) at room temperature further helped in analyzing the electrical properties of the prepared samples.

Gul, I.H., E-mail: iftikhar_qau@yahoo.com [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan); Pervaiz, Erum [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan)] [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan)

2012-06-15

231

Influence of random substitution on magnetocaloric effect in a spinel ferrite  

Microsoft Academic Search

Influence of random substitution of nonmagnetic ions on magnetocaloric effect is studied on manganese zinc ferrites from the viewpoints of Griffiths effects and frustration effects. The obtained results show that these side effects are insignificant at the ferrimagnetic transition in the range of zinc content below 70%. Consequently, the ferrite can keep a large magnetocaloric effect even when the transition

Hiroaki Mamiya; Noriki Terada; Takao Furubayashi; Hiroyuki S. Suzuki; Hideaki Kitazawa

2010-01-01

232

Mn-Zn Ferrite Powder Preparation by Hydrothermal Process from Used Dry Batteries  

Microsoft Academic Search

In this study, we propose a new process to synthesize Mn-Zn ferrite, using oxides of manganese and zinc extracted from used dry batteries, and ferrous chloride waste solution from iron plants or electronic plants recycled as starting raw materials. It is found that Mn-Zn ferrite powder prepared by the hydrothermal process from used dry batteries revealed the formation of cubic

Chung-Wen Liu; Cheng-Hsiung Lin; Yen-Pei Fu

2006-01-01

233

Rapid magnetic solid-phase extraction based on monodisperse magnetic single-crystal ferrite nanoparticles for the determination of free fatty acid content in edible oils.  

PubMed

This study proposes a rapid magnetic solid-phase extraction (MSPE) based on monodisperse magnetic single-crystal ferrite (Fe(3)O(4)) nanoparticles (NPs) for determining the quantities of eight free fatty acids (FFAs), including palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2), linolenic acid (C18:3), arachidic acid (C20:0), eicosenoic acid (C20:1), and behenic acid (C22:0) in oil. The amine-functionalized mesoporous Fe(3)O(4) magnetic NPs were applied as a sorbent for MSPE of FFAs from oil samples in a process that is based on hydrophilic interaction. The extraction can be completed rapidly in a dispersive mode with the aid of vigorous vortex. Additional tedious processing steps such as centrifugation and evaporation of organic solvent were not necessary with this procedure. Furthermore, esterification of FFAs can be accomplished during the desorption procedure by using methanol/sulfuric acid (99:1, v/v) as the desorption solvent. Several parameters affecting the extraction efficiency were investigated, including the matrix solvent for extraction, the desorption solvent and desorption time, and the amount of sorbent and extraction time. The pretreatment process was rapid under optimal conditions, being accomplished within 15 min. When coupled with gas chromatography-flame ionization detection (GC-FID), a rapid, simple, and convenient MSPE-GC-FID method for the determination of FFAs in oil samples was established with a total analysis time within 25 min. The limits of detection for the target FFAs were found to be 7.22-26.26 ng/mL. Recoveries in oil samples were in the range of 81.33-117.75%, with RSDs of <6.4% (intraday) and <6.9% (interday). This method was applied successfully to the analysis of dynamic FFA formation in four types of edible oils subjected to an accelerated storage test. The simple, rapid, and cost-effective method developed in the current study offers a potential application for the extraction and preconcentration of FFAs from hydrophobic sample matrices, including edible fats and oils, fatty foods, and biological samples with high amounts of lipid. PMID:23230865

Wei, Fang; Zhao, Qin; Lv, Xin; Dong, Xu-Yan; Feng, Yu-Qi; Chen, Hong

2013-01-01

234

Flash butt welding of high manganese steel crossing and carbon steel rail  

Microsoft Academic Search

This study sets out to introduce the flash butt welding of high manganese steel crossing and carbon steel rail by employing an austenite–ferrite two-phase stainless steel insert. There are two flash butt welded joints for the connection of the high manganese steel and the carbon steel rail, one is the welded joint of the carbon steel and the stainless steel,

Fucheng Zhang; Bo Lv; Baitao Hu; Yanguo Li

2007-01-01

235

Inverse magnetocaloric effect in sol-gel derived nanosized cobalt ferrite  

Microsoft Academic Search

The magnetocaloric properties of cobalt ferrite nanoparticles were investigated to evaluate the potential of these materials as magnetic refrigerants. Nanosized cobalt ferrites were synthesized by the method of sol-gel combustion. The nanoparticles were found to be spherical with an average crystallite size of 14 nm. The magnetic entropy change (Delta S m) calculated indirectly from magnetization isotherms in the temperature

E. Veena Gopalan; I. A. Al-Omari; D. Sakthi Kumar; Yasuhiko Yoshida; P. A. Joy; M. R. Anantharaman

2010-01-01

236

Preparation of manganese(II), chromium(III) and ferric(III) oxides nanoparticles in situ metal citraconate complexes frameworks.  

PubMed

The new reactions of some divalent and trivalent transition metal ions (Mn(II), Cr(III), and Fe(III)) with citraconic acid has been studied. The obtained results indicate the formation of citraconic acid compounds with molar ratio of metal to citraconic acid of 2:2 or 2:3 with general formulas Mn2(C5H4O4)2 or M2(C5H4O4)3?nH2O where n=6 for Cr, and Fe(III). The thermal decomposition of the crystalline solid complexes was investigated. The IR spectra of citraconate suggested that the carboxylic groups are bidentatically bridging and chelating. In the course of decomposition the complexes are dehydrated and then decompose either directly to oxides in only one step or with intermediate formation of oxocarbonates. This proposal dealing the preparation of MnO2, Fe2O3 and Cr2O3 nanoparticles. The crystalline structure of oxide products were checked by X-ray powder diffraction (XRD), and the morphology of particles by scanning electron microscopy (SEM). PMID:24952090

Refat, Moamen S

2014-12-10

237

General and Electrophysiological Toxic Effects of Manganese in Rats following Subacute Administration in Dissolved and Nanoparticle Form  

PubMed Central

In an attempt to model occupational and environmental Mn exposures and their possible interaction, young male Wistar rats were exposed to Mn by oral administration in dissolved form (MnCl2·4H2O, 14.84 and 59.36?mg/kg b.w.) and by intratracheal application of MnO2 nanoparticles (2.63?mg/kg b.w.). After 3 and 6 weeks oral, or 3 weeks oral plus 3 weeks intratracheal, exposure, general toxicological, and electrophysiological tests were done. Body weight gain was significantly reduced after 6 and 3 plus 3 weeks exposure, but the effect of the latter on the pace of weight gain was stronger. Organ weights signalized systemic stress and effect on lungs. Changes in evoked electrophysiological responses (cortical sensory evoked potential and nerve action potential) indicated that the 3 plus 3 weeks combined exposure caused equal or higher changes in the latency of these responses than 6 weeks of exposure, although the calculated summed Mn dose in the former case was lower. The results showed the importance of the physicochemical form of Mn in determining the toxic outcome, and suggested that neurofunctional markers of Mn action may indicate the human health effect better than conventional blood Mn measurement.

Horvath, Edina; Mate, Zsuzsanna; Takacs, Szabolcs; Pusztai, Peter; Sapi, Andras; Konya, Zoltan; Nagymajtenyi, Laszlo; Papp, Andras

2012-01-01

238

One-pot green synthesis of biocompatible arginine-stabilized magnetic nanoparticles.  

PubMed

A green one-step approach has been developed for the synthesis of amino-functionalized magnetite nanoparticles. The synthesis was accomplished by simply mixing FeCl2 with arginine under ambient conditions. It was found that the Fe2+/arginine molar ratio, reaction duration and temperature greatly influence the size, morphology and composition of magnetic nanoparticles. The arginine-stabilized magnetic nanoparticles were characterized by transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy techniques. The results show that the prepared nanoparticles are spherically shaped with a nearly uniform size distribution and pure magnetite phase. The presence of arginine on the magnetic nanoparticle surface has been confirmed and the amount of surface arginine varies with the Fe2+/arginine molar ratio. The surface amine densities are calculated to be 5.60 and 7.84 micromol mg(-1) for magnetic nanoparticles prepared at 1:1 and 1:2 Fe2+/arginine molar ratio, respectively. The as-synthesized nanoparticles show superparamagnetic behavior at room temperature and good solubility in water. In addition, using a similar synthesis procedure, we have been able to synthesize superparamagnetic manganese and cobalt ferrite nanoparticles. PMID:19847022

Wang, Zhongjun; Zhu, Hui; Wang, Xiaolei; Yang, Fan; Yang, Xiurong

2009-11-18

239

Electrochemical catalysis of styrene epoxidation with films of manganese dioxide nanoparticles, and, Synthesis of mixed metal oxides using ultrasonic nozzle spray and microwaves  

NASA Astrophysics Data System (ADS)

Films of polyions and octahedral layered manganese oxide (OL-1) nanoparticles on carbon electrodes made by layer-by-layer alternate electrostatic adsorption were active for electrochemical catalysis of styrene epoxidation in solution in the presence of hydrogen peroxide and oxygen. The highest catalytic turnover was obtained by using applied voltage -0.6 V vs. SCE, O2, and 100 mM H2O2. 18O isotope labeling experiments suggested oxygen incorporation from three different sources: molecular oxygen, hydrogen peroxide and/or lattice oxygen from OL-1 depending on the potential applied and the oxygen and hydrogen peroxide concentrations. Oxygen and hydrogen peroxide activate the OL-1 catalyst for the epoxidation. The pathway for styrene epoxidation in the highest yields required oxygen, hydrogen peroxide and a reducing voltage, and may involve an activated oxygen species in the OL-1 matrix. Multicomponent metal oxide (MMO) crystallites were prepared by spraying a reactant solution into a receiving solution or air under microwave radiation at atmospheric pressure. The injection of nitric acid solution through an ultrasonic nozzle into a receiving solution of metal precursor and the use of microwave radiation were combined to form a novel preparation technique called the nozzle-spray/microwave (NMW) method. The inclusion of an additional step, the in situ mixing of precursor solutions prior to their injection through the ultrasonic nozzle spray, led to another procedure called the in situ/nozzle-spray/microwave (INM) method. For comparison, MMO materials with the same metal constituents as those prepared by our novel techniques were prepared by conventional hydrothermal (CH) methods. Fresh materials prepared by NMW, INM and CH methods were heat treated to study the effect of calcination. All materials were characterized before and after calcination using XRD, SEM, Bet, and ICP. The NMW method produces particles with rod-like morphologies different from those obtained using CH methods. The INM method produces an amorphous material that crystallizes after calcination into small (˜200 nm) particles with interesting morphologies. Notably, calcination of materials prepared by both NMW and INM reduces particle size and increases surface area. The present work paves the way to use NMW and INM to prepare MMOs with unique morphologies.

Espinal, Laura

240

Magnetocaloric effect in ferrite nanoparticles  

Microsoft Academic Search

Miniaturization of the electronic devices for space, military and consumer applications requires cooling devices to be fabricated on a chip for power efficient, noise-free operations. Refrigeration based on the adiabatic-demagnetization has been used for several decades for cooling down to sub-kelvin temperatures. Superparamagnetic particles also hold tremendous potential towards this application. We have studied magnetocaloric effect (MCE) properties in chemically

D. Rebar

2005-01-01

241

A microbial fuel cell using manganese oxide oxygen reduction catalysts  

Microsoft Academic Search

Microbial fuel cells (MFCs) are a potential method for enhanced water and waste treatment, which offer the additional benefit\\u000a of energy generation. Manganese oxide was prepared by a simple chemical oxidation using potassium permanganate. Carbon-supported\\u000a manganese oxide nanoparticles were successfully characterised as cathode materials for MFCs. The manganese oxide particles\\u000a when used in a two-chamber MFC, using inoculum from an

I. Roche; K. Katuri; K. Scott

2010-01-01

242

Manganese oxide nanocomposites with improved surface area prepared by one-pot surfactant route for electro catalytic and biosensor applications  

Microsoft Academic Search

Braunite phase manganese oxide is naturally available in manganese–silicate rocks with minor amount of silicate content. New\\u000a synthetic route is attempted to prepare the manganese oxide nanoparticle and silica incorporated manganese oxide nanocomposite\\u000a in the present study. XRD patterns reveal the braunite phase formation for as synthesized manganese oxide nanocomposite and\\u000a silica incorporated MnO2 nanocomposite materials. Improved BET surface area

R. Jothiramalingam; M. K. Wang

2010-01-01

243

The effect of polyvinyl alcohol (PVA) coating on structural, magnetic properties and spin dynamics of Ni0.3Zn0.7Fe2O4 ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, the structural and magnetic properties of uncoated and polyvinyl alcohol (PVA) coated Ni0.3Zn0.7Fe2O4 ferrite nanoparticles were studied using powder X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscope (TEM), Fourier Transform Infrared spectroscopy (FTIR) and magnetic measurements. The XRD patterns indicate that the crystalline structure is single phase cubic spinel and the spinel structure is retained after PVA coating. Also, after PVA coating, the crystallite size (from Scherrer formula) increases from 17 to 24 nm. The dc magnetization measurements revealed that both samples exhibit no hysteretic behavior at room temperature, symptomatic of the superparamagnetic behavior. The estimated values of z?, ?0 and T0, using the critical slowing down model, confirm the observed variation of freezing temperatures. AC susceptibility measurements showed the magnetic responses are frequency dependent, as an applicable potential in cancer therapy. The relative sensitivity of samples to the variation of applied frequency, as an important parameter in hyperthermia based therapy, increases by coating Ni0.3Zn0.7Fe2O4 nanoparticles with PVA.

Rahimi, M.; Kameli, P.; Ranjbar, M.; Salamati, H.

2013-12-01

244

Hot coal gas desulfurization with manganese based sorbents. Quarterly report, June--September 1994  

SciTech Connect

The focus of work being performed on hot coal gas desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% Al{sub 2}O{sub 3}) appears to be a strong contender to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc; hence, it is not as likely to undergo zinc-depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron; hence, the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Also manganese chlorides are much less stable and volatile than zinc chlorides. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Eighth Quarterly Report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite.

Hepworth, M.T.; Slimane, R.B.

1994-11-01

245

A transmission electron microscopy study of CoFe2O4 ferrite nanoparticles in silica aerogel matrix using HREM and STEM imaging and EDX spectroscopy and EELS.  

PubMed

Magnetic nanocomposite materials consisting of 5 and 10 wt% CoFe2O4 nanoparticles in a silica aerogel matrix have been synthesized by the sol-gel method. For the CoFe2O4-10wt% sample, bright-field scanning transmission electron microscopy (BF STEM) and high-resolution transmission electron microscopy (HREM) images showed distinct, rounded CoFe2O4 nanoparticles, with typical diameters of roughly 8 nm. For the CoFe2O4-5wt% sample, BF STEM images and energy dispersive X-ray (EDX) measurements showed CoFe2O4 nanoparticles with diameters of roughly 3 +/- 1 nm. EDX measurements indicate that all nanoparticles consist of stoichiometric CoFe2O4, and electron energy-loss spectroscopy measurements from lines crossing nanoparticles in the CoFe2O4-10wt% sample show a uniform composition within nanoparticles, with a precision of at best than +/-0.5 nm in analysis position. BF STEM images obtained for the CoFe2O4-10wt% sample showed many "needle-like" nanostructures that typically have a length of 10 nm and a width of 1 nm, and frequently appear to be attached to nanoparticles. These needle-like nanostructures are observed to contain layers with interlayer spacing 0.33 +/- 0.1 nm, which could be consistent with Co silicate hydroxide, a known precursor phase in these nanocomposite materials. PMID:20199712

Falqui, Andrea; Corrias, Anna; Wang, Peng; Snoeck, Etienne; Mountjoy, Gavin

2010-04-01

246

Synthesis of magnetic spinel ferrite CoFe2O4 nanoparticles from ferric salt and characterization of the size-dependent superparamagnetic properties  

Microsoft Academic Search

The CoFe 2 O 4 nanoparticles have been synthesized by using a stable ferric salt of FeCl 3 with a micellar microemulsion method. The normal micelles are formed by sodium dodecyl sulfate (NaDS) in aqueous solutions. The mean size of the nanoparticles can be controlled from less than 4 nm to about 10 nm through controlling the concentrations of the

Chao Liu; Adam J. Rondinone; Z. John

2000-01-01

247

Effect of Mg substitution on the magnetic properties of NiCuZn ferrite nanoparticles prepared through a novel method using egg white  

NASA Astrophysics Data System (ADS)

Nanocrystalline Mg-substituted NiCuZn ferrites were successfully synthesized, for the first time, by using metal nitrates and freshly extracted egg white. The thermal decomposition process of the nitrate-egg white precursors was investigated by thermogravimetric (TG) technique. X-ray diffraction (XRD) revealed that, single-phase cubic ferrites with average particle size of 23.9-35.1 nm were directly formed after ignition at 500 °C. No noticeable variation of lattice parameters with increasing magnesium content was observed, while X-ray densities were found to decrease. This can be explained on the basis of ionic radii and atomic masses of the substituted cation. Transmission electron microscope (TEM) shows that, particles are permanently magnetized and get agglomerated. The saturation magnetization ( M s) and coercivity ( H c) as a function of Mg content were investigated using vibrating sample magnetometer (VSM). It has been found that the M s increases firstly up to x=0.2 and then decreases, while H c continuously decreases. Magnetic susceptibility measurements give results which agree well with those obtained by VSM. The obvious decrease in the Curie temperature ( T C) with increasing Mg indicates that the ferrimagnetic grains are widely separated and enclosed by non-magnetic magnesium ions.

Gabal, M. A.

2009-10-01

248

Hot coal gas desulfurization with manganese-based sorbents. Progress report, April 1, 1993--June 30, 1993  

SciTech Connect

Focus of work is primarily in use of zinc ferrite and zinc titanate sorbents; however, an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc, hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. Thermodynamic analysis of the system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese higher temperatures than zinc ferrite or titanate. This report gives the thermodynamic background for consideration of manganese-based sorbents as an alternative to zinc ferrite. To date the work is limited to thermogravimetric testing of four formulations of manganese-alumina sorbents to determine the optimum conditions of pelletization and enduration to produce reactive pellets.

Hepworth, M.T.

1993-07-15

249

Hot Coal Gas Desulfurization with manganese based sorbents. Quarterly report, August 1, 1993--September 30, 1993  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E. T. Turkdogan indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This report documents progress in pelletizing and testing via thermogravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite. Preliminary results indicate that the manganese carbonate material, being of higher purity than the manganese ore, has a higher degree of sulfur capacity and more rapid absorption kinetics. A 2-inch fixed-bed reactor has been fabricated and is now ready for subjecting pellets to cyclic loading and regeneration.

Hepworth, M.T.

1993-10-01

250

Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles  

PubMed Central

The optical properties of multi-functionalized cobalt ferrite (CoFe2O4), cobalt zinc ferrite (Co0.5Zn0.5Fe2O4), and zinc ferrite (ZnFe2O4) nanoparticles have been enhanced by coating them with silica shell using a modified Stöber method. The ferrites nanoparticles were prepared by a modified citrate gel technique. These core/shell ferrites nanoparticles have been fired at temperatures: 400°C, 600°C and 800°C, respectively, for 2 h. The composition, phase, and morphology of the prepared core/shell ferrites nanoparticles were determined by X-ray diffraction and transmission electron microscopy, respectively. The diffuse reflectance and magnetic properties of the core/shell ferrites nanoparticles at room temperature were investigated using UV/VIS double-beam spectrophotometer and vibrating sample magnetometer, respectively. It was found that, by increasing the firing temperature from 400°C to 800°C, the average crystallite size of the core/shell ferrites nanoparticles increases. The cobalt ferrite nanoparticles fired at temperature 800°C; show the highest saturation magnetization while the zinc ferrite nanoparticles coated with silica shell shows the highest diffuse reflectance. On the other hand, core/shell zinc ferrite/silica nanoparticles fired at 400°C show a ferromagnetic behavior and high diffuse reflectance when compared with all the uncoated or coated ferrites nanoparticles. These characteristics of core/shell zinc ferrite/silica nanostructures make them promising candidates for magneto-optical nanodevice applications.

2011-01-01

251

Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles.  

PubMed

The optical properties of multi-functionalized cobalt ferrite (CoFe2O4), cobalt zinc ferrite (Co0.5Zn0.5Fe2O4), and zinc ferrite (ZnFe2O4) nanoparticles have been enhanced by coating them with silica shell using a modified Stöber method. The ferrites nanoparticles were prepared by a modified citrate gel technique. These core/shell ferrites nanoparticles have been fired at temperatures: 400°C, 600°C and 800°C, respectively, for 2 h. The composition, phase, and morphology of the prepared core/shell ferrites nanoparticles were determined by X-ray diffraction and transmission electron microscopy, respectively. The diffuse reflectance and magnetic properties of the core/shell ferrites nanoparticles at room temperature were investigated using UV/VIS double-beam spectrophotometer and vibrating sample magnetometer, respectively. It was found that, by increasing the firing temperature from 400°C to 800°C, the average crystallite size of the core/shell ferrites nanoparticles increases. The cobalt ferrite nanoparticles fired at temperature 800°C; show the highest saturation magnetization while the zinc ferrite nanoparticles coated with silica shell shows the highest diffuse reflectance. On the other hand, core/shell zinc ferrite/silica nanoparticles fired at 400°C show a ferromagnetic behavior and high diffuse reflectance when compared with all the uncoated or coated ferrites nanoparticles. These characteristics of core/shell zinc ferrite/silica nanostructures make them promising candidates for magneto-optical nanodevice applications. PMID:21774807

Girgis, Emad; Wahsh, Mohamed Ms; Othman, Atef Gm; Bandhu, Lokeshwar; Rao, Kv

2011-01-01

252

Sol-gel derived nanoparticles of Zn substituted lithium ferrite (Li 0.32Zn 0.36Fe 2.32O 4): magnetic and Mössbauer effect measurements and their theoretical analysis  

NASA Astrophysics Data System (ADS)

Nanoparticles of Zn substituted lithium ferrite (Li 0.32Zn 0.36Fe 2.32O 4) have been prepared by a sol-gel method where the ultra-sonication technique has been adopted to reduce the agglomeration effect among the nanoparticles. The samples were heat-treated at three different temperatures and the formation of the nanocrystalline phase was confirmed by X-ray diffractograms (XRD). The average particle size of each sample has been estimated from the (311) peak of the XRD pattern using the Debye-Scherrer formula and the average sizes are in the range of 10-21 nm. The average particle size, crystallographic phase, etc. of some selected samples obtained from the high-resolution transmission electron microscopy are in agreement with those estimated from the XRD patterns. Static magnetic measurements viz., hysteresis loops, field cooled and zero field cooled magnetization versus temperature curves of some samples carried out by SQUID in the temperature range of 300 to 5 K clearly indicate the presence of superparamagnetic (SPM) relaxation of the nanoparticles in the samples. The maximum magnetization of the SPM sample annealed at 500 °C is quite high (68 Am 2/Kg) and the hysteresis loops are almost square shaped with very low value of coercive field at room temperature (827.8 A/m). The particle size, magneto-crystalline anisotropy, etc. have been estimated from the detailed theoretical analysis of the static magnetic data. The dynamic magnetic behavior of the samples was also investigated by observing the ac hysteresis loops and magnetization versus field curves with different time windows at room temperatures. The different soft magnetic quantities viz., coercive field, magnetization, remanance, hysteresis losses, etc. were extracted from dynamic measurements. Dynamic measurements confirmed that the samples are in their mixed state of SPM and ordered ferrimagnetic particles, which is in good agreement with the results of static magnetic measurements. Mössbauer spectra of the samples recorded at room temperature (300 K) and at different temperatures down to 20 K confirmed the presence of the SPM relaxation of the nanoparticles of the samples.

Sutradhar, S.; Pati, S.; Acharya, S.; Das, S.; Das, D.; Chakrabarti, P. K.

2012-04-01

253

Effect of manganese and nitrogen on the solidification mode in austenitic stainless steel welds  

NASA Astrophysics Data System (ADS)

The macrostructures and microstructures of thirty different austenitic stainless welds alloyed with manganese and Jor nitrogen are analyzed. Comparison of the results with those obtained from normal welds of the AISIJAWS 300 series indicates that the solidification mode and Ferrite Number can be predicted adequately using chromium and nickel equivalents. The solidification mode in the normal and nitrogen-alloyed welds can be best described by the equivalents developed by Hammar and Svensson and the Ferrite Number by the conventional Schaeffler-DeLong diagram. Both of these descriptions are invalid at high manganese content values (5 to 8 pct), however, in which case Hull’s equivalents give a better correlation between the composition and the solidification mode or Ferrite Number. The complicated role of manganese and the austenite-favoring effect of nitrogen in austenitic stainless steels are discussed.

Suutala, N.

1982-12-01

254

The Effect of Alkali Concentration on the Structural and Magnetic Properties of Mn-Ferrite Nanoparticles Prepared via the Coprecipitation Method  

NASA Astrophysics Data System (ADS)

MnFe2O4 nanoparticles were synthesized using the coprecipitation method under two different NaOH concentration settings as reaction agents at 355 K (82 °C). Structural and morphological properties of the nanoparticles were examined using X-ray diffraction and a scanning electron microscope. The decrease of NaOH concentration led to the increase of particle size. This result contradicts two recently published reports. Also, the decrease of NaOH concentration led to more crystallinity and a narrower particle size distribution. The results were evaluated from a chemical point of view and were based on the supersaturation level, which was influenced by alkali concentration. It was concluded that the higher NaOH concentration led to a more rapid nucleation and more random cation distribution. The magnetic properties of the nanoparticles examined by permeameter and faraday-balance equipment were consistent with the structural and morphological properties of the particles.

Pourbafarani, Somayeh

2014-05-01

255

Preparation and magnetic properties of Zn-Cu-Cr-La ferrite and its nanocomposites with polyaniline.  

PubMed

Nanosized Zn(0.6)Cu(0.4)Cr(0.5)Fe(1.5-x)La(x)O(4) (x=0 - 0.06) ferrites doped with La are synthesized by a rheological phase reaction method. Polyaniline (PANI)/ferrite nanocomposites are prepared by in situ polymerization method. The structure, morphology and ferromagnetic property of ferrite powders and nanocomposites are characterized by X-ray powder diffractometer (XRD), transmission electron microscope (TEM), Fourier transform infrared spectra (FTIR), UV-visible spectroscopy (UV), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). The results indicate that the PANI and nanosized ferrite powders can be combined effectively. The polymers can reduce the agglomeration of nanosized ferrite particles to some extent, which is good for the dispersedness and stabilization of nanoparticles. The PANI/ferrite nanocomposites under applied magnetic field exhibit the hysteretic loops of the ferromagnetic nature. The magnetic properties of nanocomposites are tailored by controlling the ferrite content. PMID:18313067

Li, Liangchao; Liu, Hui; Wang, Yuping; Jiang, Jing; Xu, Feng

2008-05-15

256

Synthesis of high-coercivity cobalt ferrite particles using water-in-oil microemulsions  

Microsoft Academic Search

Magnetic nanoparticles of cobalt ferrite (CoFe2O4) have been synthesized using water-in-oil microemulsions consisting of water, cetyl trimethyl ammonium bromide (surfactant), n-butanol (cosurfactant), and n-octane (oil). Precursor hydroxides were precipitated in the aqueous cores of water-in-oil microemulsions and these were then separated and calcined to give the magnetic oxide. X-ray diffraction confirmed the formation of phase pure cobalt ferrite. These nanoparticles

V. Pillai; D. O. Shah

1996-01-01

257

Magnetic nanoparticles  

Microsoft Academic Search

Intrinsic properties of magnetic nanoparticles are reviewed, with special emphasis on the effects of finite size on zero-temperature spin ordering, magnetic excitations, and relaxation. Effects on zero-temperature spin ordering include moment enhancement due to band narrowing in 3d transition metal particles, surface spin disorder in ferrite particles, and multi-sublattice states in antiferromagnetic oxide particles. Magnetic excitations include discretized spin wave

R. H Kodama

1999-01-01

258

Chronic manganese intoxication  

SciTech Connect

We report six cases of chronic manganese intoxication in workers at a ferromanganese factory in Taiwan. Diagnosis was confirmed by assessing increased manganese concentrations in the blood, scalp, and pubic hair. In addition, increased manganese levels in the environmental air were established. The patients showed a bradykinetic-rigid syndrome indistinguishable from Parkinson's disease that responded to treatment with levodopa.

Huang, C.C.; Chu, N.S.; Lu, C.S.; Wang, J.D.; Tsai, J.L.; Tzeng, J.L.; Wolters, E.C.; Calne, D.B. (Chang Gung Medical College Hospital, Taipei, Taiwan (China))

1989-10-01

259

Corrosion cracking and hydrogen embrittlement of two-phase austenite-ferrite steels  

SciTech Connect

The authors study the resistance to corrosion cracking and hydrogen embrittlement of austenite-ferrite steels based on 25% chromium and 5.5% nickel in a series of destructive mechanical tests in solutions of boiling magnesium chloride. The effects of additions of manganese, yttrium, zirconium, nitrogen, tungsten, and silicon and their abilities to enhance or detract from the resistance are comparatively assessed.

Malkin, V.I.; Fel'dgandler, E.G.

1987-03-01

260

Monodisperse cobalt ferrite nanomagnets with uniform silica coatings.  

PubMed

Ferro- and ferrimagnetic nanoparticles are difficult to manipulate in solution as a consequence of the formation of magnetically induced nanoparticle aggregates, which hamper the utility of these particles for applications ranging from data storage to bionanotechnology. Nonmagnetic shells that encapsulate these magnetic particles can reduce the interparticle magnetic interactions and improve the dispersibility of the nanoparticles in solution. A route to create uniform silica shells around individual cobalt ferrite nanoparticles--which uses poly(acrylic acid) to bind to the nanoparticle surface and inhibit nanoparticle aggregation prior to the addition of a silica precursor--was developed. In the absence of the poly(acrylic acid) the cobalt ferrite nanoparticles irreversibly aggregated during the silica shell formation. The thickness of the silica shell around the core-shell nanoparticles could be controlled in order to tune the interparticle magnetic coupling as well as inhibit magnetically induced nanoparticle aggregation. These ferrimagnetic core-silica shell structures form stable dispersion in polar solvents such as EtOH and water, which is critical for enabling technologies that require the assembly or derivatization of ferrimagnetic particles in solution. PMID:20961061

Dai, Qiu; Lam, Michelle; Swanson, Sally; Yu, Rui-Hui Rachel; Milliron, Delia J; Topuria, Teya; Jubert, Pierre-Olivier; Nelson, Alshakim

2010-11-16

261

Hot coal gas desulfurization with manganese-based sorbents. Quarterly report, October--December 1993  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Fifth Quarterly Report documents progress in pellet testing via thermogravimetric analysis of pellet formulation FORM4-A of a manganese ore/alumina combination. This formulation, described more fully in the Quarterly Technical Progress Report of October 15, 1993, consists of manganese carbonate combined with alundum. A 2-inch fixed-bed reactor has been fabricated and is now ready for subjecting pellets to cyclic loading and regeneration; however, a minor problem has arisen during the regeneration cycle in that sulfur tends to form and plug the exit tube during the early stage of regeneration. This problem is about to be overcome by increasing the flow rate of air during the regeneration cycle resulting in more oxidizing conditions and hence less tendency for sulfide sulfur (S{sup =}) to oxidize to the intermediate elemental form (S{sup o}) rather than to 4-valent (S{sup +4}).

Hepworth, M.T.; Slimane, R.B.

1994-01-01

262

Low temperature synthesis of nanocrystalline lithium ferrite by a modified citrate gel precursor method  

SciTech Connect

Single phase nanocrystalline lithium ferrite is synthesized by a modified citrate gel precursor technique. Ferrite nanoparticles of average size of 8 nm, obtained after calcination of the citrate gel made by the usual method at 450 deg. C, show superparamagnetic behavior. However, small amounts of {alpha}-Fe{sub 2}O{sub 3} is formed as an impurity phase due to the initial formation of some {gamma}-Fe{sub 2}O{sub 3} phase. On the other hand, when the pH of the mixed solution is increased to 7 after the addition of ammonia solution, a lower calcination temperature of 200 deg. C is sufficient for the formation of single phase lithium ferrite nanoparticles of size 30 nm. No impurity phases are detected when the nanocrystalline powders are calcined at higher temperatures. The magnetic properties of the ferrite nanoparticles of different sizes obtained by calcining the powders at different temperatures are studied.

Verma, Seema [Physical and Materials Chemistry Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008 (India); Joy, P.A. [Physical and Materials Chemistry Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008 (India)], E-mail: pa.joy@ncl.res.in

2008-12-01

263

Manganese laser using manganese chloride as lasant  

NASA Technical Reports Server (NTRS)

A manganese vapor laser utilizing manganese chloride as a lasant has been observed and investigated. Lasing is attained by means of two consecutive electrical discharges. The maximum laser output is obtained at a vapor pressure of about 3 torr, a temperature of 680 C, and a time delay between electrical discharges of 150 microsec. The maximum energy density is 1.3 microjoule per cu cm.

Chen, C. J.

1974-01-01

264

Hot Coal Gas Desulfurization with manganese-based sorbents. Quarterly report, April--June 1994  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% Al{sub 2}O{sub 3}) appears to be a strong contender to zincbased sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc; hence, it is not as likely to undergo zinc-depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron; hence, the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Also manganese chlorides are much less stable and volatile than zinc chlorides. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Seventh Quarterly Report documents progress in bench-scale testing of a leading manganese-based sorbent pellets (FORM4-A). This formulation is a high-purity manganese carbonate-based material. This formulation was subjected to 20 consecutive cycles of sulfidation and regeneration at 900{degrees}C in a 2-inch fixed bed reactor. The sulfidation gas was a simulated Tampella U-gas with an increased hydrogen sulfide content of 3% by volume to accelerate the rate of breakthrough, arbitrarily taken as 500 ppmv. Consistent with thermo-gravimetric analysis (TGA) on individual pellets, the fixed bed tests show small improvement in capacity and kinetics with the sulfur-loading capacity being about 22% by weight of the original pellet, which corresponds to approximately 90% bed utilization!

Hepworth, M.T.; Slimane, R.B.

1994-06-01

265

Size-Selective Chemical Synthesis of Tartrate Stabilized Cobalt Ferrite Ionic Magnetic Fluid  

Microsoft Academic Search

Ionic magnetic fluid (ferrofluid) is a stable suspension of magnetic nanoparticles in water. Cobalt ferrite nanoparticles are interesting in view of high-density recording storage. The size of the magnetic particles strongly influences the physical properties of the ferrofluids. In this study, we describe the synthesis of ionic magnetic fluid in the presence of tartrate ions. By varying the amount of

S. Neveu; A. Bee; M. Robineau; D. Talbot

2002-01-01

266

Formation and evolution of magnetic nanoparticles in borate glass simultaneously doped with Fe and Mn oxides  

NASA Astrophysics Data System (ADS)

Evolution of the phase state of paramagnetic additions at various stages of synthesis and subsequent thermal treatment of glasses of the system Al2O3-K2O-B2O3 simultaneously doped with Fe2O3 and MnO is studied by means of a combination of experimental techniques: Faraday rotation (FR), electron magnetic resonance (EMR), transmission electron microscopy (TEM), Mössbauer spectroscopy, and magnetic measurements. Both FR and EMR show that magnetically ordered clusters occur already at the first stage of the glass preparation. In particular, for the ratio of the Fe and Mn oxides in the charge close to 3:2, fine magnetic nanoparticles are formed with characteristics similar to those of manganese ferrite. By computer simulating the EMR spectra at variable temperatures, a superparamagnetic nature of these nanoparticles is confirmed and their mean diameter is estimated as approximately 3.2 nm. In the thermally treated glasses larger magnetic nanoparticles are formed, giving rise to FR spectra, characteristic of magnetically ordered systems, and the EMR spectra different from those in as-prepared glasses but also showing superparamagnetic narrowing. The Mössbauer spectroscopy corroborates the manganese ferrite structure of the nanoparticles and indicates their coexistence in the ferrimagnetic and superparamagnetic states. The TEM shows the presence of polydisperse nanoparticles on the background of the glass matrix, and electron diffraction of a selected region containing larger particles indicates a crystal structure close to that of MnFe2O4. Energy-dispersive atomic x-ray spectra confirm that the major part of Fe and Mn introduced to the glass composition is gathered in the particles, with the concentration ratio close to 2:1, characteristic of bulk MnFe2O4. Magnetic hysteresis loops of samples subjected to an additional thermal treatment demonstrate a strong increase in the coercive force, remnant magnetization, and high-field magnetic susceptibility with temperature decrease. The consistent results obtained using various techniques demonstrate that the formation of nanoparticles with characteristics close to those of MnFe2O4 confers to these glasses magnetic and magneto-optical properties typical of substances possessing magnetic order.

Kliava, J.; Edelman, I.; Ivanova, O.; Ivantsov, R.; Bayukov, O.; Petrakovskaja, E.; Zaikovskiy, V.; Bruckental, I.; Yeshurun, Y.; Stepanov, S.

2008-11-01

267

Magnetic memory effects in nickel ferrite/polymer nanocomposites  

NASA Astrophysics Data System (ADS)

Memory effects are reported in the field cooled (FC) magnetization of pure nickel ferrite powders and nickel ferrite nanocomposites prepared by the solution casting method. Studies carried out at different concentrations of the nanocomposite indicate that memory effects are suppressed with increasing concentration of the magnetic component in the nanocomposite. This is linked to the increase in the dipolar interaction strength in the nanocomposites, which increase with increasing concentration, as confirmed by the Henkel plots. Model simulations of the FC magnetization carried out on an interacting array of monodispersed magnetic nanoparticles indicate that growing cluster sizes inhibit memory effects.

Malik, Rakesh; Sehdev, Neeru; Lamba, Subhalakshmi; Sharma, Parmanand; Makino, Akihiro; Annapoorni, Subramanian

2014-03-01

268

Magnetic and magnetostrictive properties of manganese substituted cobalt ferrite  

Microsoft Academic Search

The magnetic and magnetostrictive properties of polycrystalline\\u000a Co1-xMnxFe2O4 ( 0 = x = 0.4) have been studied. Although the Curie\\u000a temperature decreases continuously with increasing concentration of Mn,\\u000a the magnetization remains high up to x = 0.3 and unexpectedly low\\u000a coercivity is observed for this composition showing an unusual\\u000a magnetostrictive behaviour. This composition shows a relatively larger\\u000a magnetostriction at low

S. D. Bhame; P. A. Joy

2007-01-01

269

FDTD modeling of lumped ferrites  

Microsoft Academic Search

Implementing ferrites in finite-difference time-domain (FDTD) modeling requires special care because of the complex nature of the ferrite impedance. Considerable computational resources and time are required to directly implement a ferrite in the FDTD method. Fitting the ferrite impedance to an exponential series with the generalized-pencil-of-function (GPOF) method and using recursive convolution is an approach that minimizes the additional computational

Min Li; Xiao Luo; James L. Drewniak

2000-01-01

270

Impedance calculation for ferrite inserts  

SciTech Connect

Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. They study the narrowband longitudinal impedance of these ferrite inserts. they find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. They also provide a recipe for attaining a truly passive space charge impedance compensation and avoiding narrowband microwave instabilities.

Breitzmann, S.C.; Lee, S.Y.; /Indiana U.; Ng, K.Y.; /Fermilab

2005-01-01

271

BIOLOGICAL EFFECTS OF MANGANESE  

EPA Science Inventory

The biological effects of manganese were studied in a town on the coast of Dalmatia in which a ferromanganese plant has been operating since before World War II. The study focused on the question of whether the exposure to manganese can cause a higher incidence of respiratory dis...

272

Microwave ferrite materials and devices  

Microsoft Academic Search

The crystal structure of ferrites including garnets and their methods of preparation are first reviewed. This is followed by an examination of microwave ferrite devices and their application to actual systems. Sufficient theoretical details as well as an extensive though not exhaustive list of references are included for ready reference. The most widely used microwave ferrite device is the isolator,

R. Soohoo

1968-01-01

273

Size-dependent superparamagnetic properties of MgFe2O4 spinel ferrite nanocrystallites  

Microsoft Academic Search

Superparamagnetism is a unique and important aspect of magnetism in nanoparticles. The superparamagnetic properties of the MgFe2O4 spinel ferrite nanoparticles with the particle size from about 6 to 18 nm are studied. The blocking temperature is a function of the particle size and increases with increasing particle size. The coercivity of MgFe2O4 nanoparticles also is a function of the particle

Qi Chen; Z. John Zhang

1998-01-01

274

Nanoparticles  

NASA Astrophysics Data System (ADS)

Nanostructured bulk materials are regarded as a means of enhancing the performance of thermoelectric (TE) materials and devices. Powder metallurgy has the distinct advantage over conventional synthesis that it can start directly from nanosized particles. However, further processing, for example extrusion, usually requires elevated temperatures, which lead to grain growth. We have found that introduction of semiconductor nanoparticles of molybdenum disulfide (MoS2), a well-known solid lubricant, suppresses grain growth in bismuth telluride-based alloys, thus improving the extrusion process. Scanning electron microscope images show that adding MoS2 particles at concentrations of 0.2, 0.4, and 0.8 wt% to p-type (Bi0.2Sb0.8)2Te3, under otherwise identical extrusion conditions, reduces average grain size by a factor of four. Scherer's formula applied to x-ray diffraction data indicates that average crystallite sizes (˜17 nm) of powders are not significantly different from those of alloys extruded with MoS2 (˜18 nm), which is in stark contrast with those for conventional alloy (Bi0.2Sb0.8)2Te3 extruded under the same conditions (˜80 nm). Harman measurements of TE properties reveal a decrease of the thermal conductivity accompanied by reduction of the room-temperature figure of merit ( ZT) from 0.9 to 0.7, because of a lower power factor. Above 370 K, however, the performance of alloys containing MoS2 surpasses that of (Bi0.2Sb0.8)2Te3, with reduction of the thermal conductivity which is more significant at temperatures above the cross point of the ZT values.

Keshavarz, Mohsen K.; Vasilevskiy, Dimitri; Masut, Remo A.; Turenne, Sylvain

2014-06-01

275

Ferrite logic reliability study  

NASA Technical Reports Server (NTRS)

Development and use of digital circuits called all-magnetic logic are reported. In these circuits the magnetic elements and their windings comprise the active circuit devices in the logic portion of a system. The ferrite logic device belongs to the all-magnetic class of logic circuits. The FLO device is novel in that it makes use of a dual or bimaterial ferrite composition in one physical ceramic body. This bimaterial feature, coupled with its potential for relatively high speed operation, makes it attractive for high reliability applications. (Maximum speed of operation approximately 50 kHz.)

Baer, J. A.; Clark, C. B.

1973-01-01

276

Effect of Cadmium Substitution on Structural and Magnetic Properties of Nano Sized Nickel Ferrite  

NASA Astrophysics Data System (ADS)

The structure and crystal phase of the nanocrystalline powders of Ni1-xCdxFe2O4 (0<=x<=0.5) mixed ferrite, synthesized by wet chemical co-precipitation method, were characterized by X-ray diffraction. Results showed that the lattice parameter increased with increasing Cd concentration. Microstructure was studied by scanning electron microscopy. TG/DTA studies were carried out on co-precipitated sulphate complexes. These studies revealed the low ferritization temperature (650 °C) of the ferrite system synthesized by presently adopted route of synthesis and occurrence of simultaneous decomposition and ferritization processes. Further studies by infrared spectroscopy were also conducted. Moreover, magnetic properties of the prepared nanoparticles were studied by magnetization and a.c. susceptibility measurements. The response of prepared Ni1-xCdxFe2O4 mixed ferrites to magnetic field was investigated. Results show that, magnetic susceptibility, Curie temperature, and effective magnetic moment decreased as the Cd content increases.

Pralhadrao Jadhav, Sanjay; Ghanshamji Toksha, Bhagwan; Marutirao Jadhav, Kamalakar; Dadarao Shinde, Narayan

2010-08-01

277

nanoparticles  

NASA Astrophysics Data System (ADS)

In this work, we present the role of vanadium ions (V+5 and V+3), oxygen vacancies (VO), and interstitial zinc (Zni) to the contribution of specific magnetization for a mixture of ZnO-V2O5 nanoparticles (NPs). Samples were obtained by mechanical milling of dry powders and ethanol-assisted milling for 1 h with a fixed atomic ratio V/Zn?=?5% at. For comparison, pure ZnO samples were also prepared. All samples exhibit a room temperature magnetization ranging from 1.18?×?10-3 to 3.5?×?10-3 emu/gr. Pure ZnO powders (1.34?×?10-3 emu/gr) milled with ethanol exhibit slight increase in magnetization attributed to formation of Zni, while dry milled ZnO powders exhibit a decrease of magnetization due to a reduction of VO concentration. For the ZnO-V2O5 system, dry milled and thermally treated samples under reducing atmosphere exhibit a large paramagnetic component associated to the formation of V2O3 and secondary phases containing V+3 ions; at the same time, an increase of VO is observed with an abrupt fall of magnetization to ??~?0.7?×?10-3 emu/gr due to segregation of V oxides and formation of secondary phases. As mechanical milling is an aggressive synthesis method, high disorder is induced at the surface of the ZnO NPs, including VO and Zni depending on the chemical environment. Thermal treatment restores partially structural order at the surface of the NPs, thus reducing the amount of Zni at the same time that V2O5 NPs segregate reducing the direct contact with the surface of ZnO NPs. Additional samples were milled for longer time up to 24 h to study the effect of milling on the magnetization; 1-h milled samples have the highest magnetizations. Structural characterization was carried out using X-ray diffraction and transmission electron microscopy. Identification of VO and Zni was carried out with Raman spectra, and energy-dispersive X-ray spectroscopy was used to verify that V did not diffuse into ZnO NPs as well to quantify O/Zn ratios.

Olive-Méndez, Sion F.; Santillán-Rodríguez, Carlos R.; González-Valenzuela, Ricardo A.; Espinosa-Magaña, Francisco; Matutes-Aquino, José A.

2014-04-01

278

Tensile Behavior of Ferrite-Carbide and Ferrite-Martensite Steels with Different Ferrite Grain Structures  

NASA Astrophysics Data System (ADS)

Ferrite-carbide and ferrite-martensite dual-phase microstructures have been produced in a low-carbon steel with different ferrite grain structures such as, uniform distribution of coarse- and very fine-ferrite grains, and bimodal distribution of ferrite grain sizes comprising of coarse grains (~12 ?m) and very fine grains (<2 ?m). Very fine-grained dual-phase structure offered the best combination of tensile-strength and ductility among all the samples. The above microstructures have been compared in terms of their strain-hardening rate and the mechanism of plastic deformation.

Karmakar, Anish; Sivaprasad, S.; Kundu, S.; Chakrabarti, Debalay

2014-04-01

279

Ruthenium doped lithium ferrite  

NASA Astrophysics Data System (ADS)

The maximum solubility of ruthenium in lithium ferrite, xlim, in the temperature range 1000 to 1300°C is related to the firing temperature T(°C) by the empirical formula xlim = 1.1 × 10 -3( T-900). The ruthenium enters the octahedral (B) sites of the spinel structure as Ru 3+ ions in a low spin state.

Mills-Goodlet, R. P.; Nixon, D. E.; Pointon, A. J.

1980-01-01

280

Ruthenium doped lithium ferrite  

Microsoft Academic Search

The maximum solubility of ruthenium in lithium ferrite, xlim, in the temperature range 1000 to 1300°C is related to the firing temperature T(°C) by the empirical formula xlim = 1.1 × 10-3(T-900). The ruthenium enters the octahedral (B) sites of the spinel structure as Ru3+ ions in a low spin state.

R. P. Mills-Goodlet; D. E. Nixon; A. J. Pointon

1980-01-01

281

XXIst Century Ferrites  

Microsoft Academic Search

Ferrites have always been a subject of great interest from point of view of magnetic application, since the fist compass to present date. In contrast, the scientific interest for iron based magnetic oxides decreased after Ørsted discovery as they where replaced by coil as magnetizing sources. Neel discovery of ferrimagnetism boosted again interest and leads to strong developments during two

F Mazaleyrat; K Zehani; A Pasko; V Loyau; M LoBue

2012-01-01

282

Longitudinal MRI contrast enhanced monitoring of early tumour development with manganese chloride (MnCl2) and superparamagnetic iron oxide nanoparticles (SPIOs) in a CT1258 based in vivo model of prostate cancer  

PubMed Central

Background Cell lines represent a key tool in cancer research allowing the generation of neoplasias which resemble initial tumours in in-vivo animal models. The characterisation of early tumour development is of major interest in order to evaluate the efficacy of therapeutic agents. Magnetic resonance imaging (MRI) based in-vivo characterisation allows visualisation and characterisation of tumour development in early stages prior to manual palpation. Contrast agents for MRI such as superparamagnetic iron oxide nanoparticles (SPIOs) and manganese chloride (MnCl2) represent powerful tools for the in-vivo characterisation of early stage tumours. In this experimental study, we labelled prostate cancer cells with MnCl2 or SPIOs in vitro and used 1?T MRI for tracing labelled cells in-vitro and 7?T MRI for tracking in an in-vivo animal model. Methods Labelling of prostate cancer cells CT1258 was established in-vitro with MnCl2 and SPIOs. In-vitro detection of labelled cells in an agar phantom was carried out through 1?T MRI while in-vivo detection was performed using 7?T MRI after subcutaneous (s.c.) injection of labelled cells into NOD-Scid mice (n?=?20). The animals were scanned in regular intervals until euthanization. The respective tumour volumes were analysed and corresponding tumour masses were subjected to histologic examination. Results MnCl2in-vitro labelling resulted in no significant metabolic effects on proliferation and cell vitality. In-vitro detection-limit accounted 105 cells for MnCl2 as well as for SPIOs labelling. In-vivo 7?T MRI scans allowed detection of 103 and 104 cells. In-vivo MnCl2 labelled cells were detectable from days 4–16 while SPIO labelling allowed detection until 4?days after s.c. injection. MnCl2 labelled cells were highly tumourigenic in NOD-Scid mice and the tumour volume development was characterised in a time dependent manner. The amount of injected cells correlated with tumour size development and disease progression. Histological analysis of the induced tumour masses demonstrated characteristic morphologies of prostate adenocarcinoma. Conclusions To the best of our knowledge, this is the first study reporting direct in-vitro MnCl2 labelling and 7?T based in-vivo MRI tracing of cancer cells in a model of prostate cancer. MnCl2 labelling was found to be suitable for in-vivo tracing allowing long detection periods. The labelled cells kept their highly tumourigenic potential in-vivo. Tumour volume development was visualised prior to manual palpation allowing tumour characterisation in early stages of the disease.

2012-01-01

283

Inverse magnetocaloric effect in sol-gel derived nanosized cobalt ferrite  

Microsoft Academic Search

The magnetocaloric properties of cobalt ferrite nanoparticles were\\u000a investigated to evaluate the potential of these materials as magnetic\\u000a refrigerants. Nanosized cobalt ferrites were synthesized by the method\\u000a of sol-gel combustion. The nanoparticles were found to be spherical with\\u000a an average crystallite size of 14 nm. The magnetic entropy change (Delta\\u000a S (m)) calculated indirectly from magnetization isotherms in the\\u000a temperature

E. Veena Gopalan; I. A. Al-Omari; D. Sakthi Kumar; Yasuhiko Yoshida; P. A. Joy; M. R. Anantharaman

2010-01-01

284

A frequency-dependent hysteresis model for power ferrites up to curie temperatures  

Microsoft Academic Search

A methodology is presented for the modeling of hysteresis in bulk manganese-zinc (MnZn) power ferrites over the practical ranges of amplitude and frequency from room temperature up to their Curie temperatures. The model parameters of an existing frequency-dependent hysteresis model are related to the typical magnetic properties such as the saturation flux density, the coercive force, and initial permeability. Temperature

Paiboon Nakmahachalasint; Khai D. T. Ngo; Loc Vu-Quoc

2004-01-01

285

Calculation of exchange constants in spinel ferrites with magnetic S-state ions  

NASA Astrophysics Data System (ADS)

The exchange constants in spinel ferrites with S-state ions, including magnesium ferrite, lithium ferrite, and manganese ferrite, were calculated using modified Becke's three-parameter density functional, where the percentage of Hartree-Fock exchange in total exchange was introduced as a variable parameter (w) to match the experimental results of exchange constants by controlling the localization and delocalization of the electrons. Consistently, the scaling factor of the 3d orbitals of ferric ions was also introduced as a variable parameter (?). From the calculation, the values of parameters w and ? matching the experimental results of JAB (nearest-neighbor exchange constant between tetrahedral and octahedral sublattices) were concentrative, while those matching the experimental results of JAA (nearest-neighbor exchange constant inside tetrahedral sublattice) and JBB (nearest-neighbor exchange constant inside octahedral sublattice) were dispersive. Observing that JAB is dominant in most practical ferrimagnetic spinel ferrites and the current accuracy of the measurements of JBB and JAA may be insufficient to support more accurate conclusion, it is suggested that there may be an empirical universal law of parameters w and ? for spinel ferrites with S-state ions.

Zuo, Xu; He, Yongxue; Yang, Aria; Bernardo, Barbiellini; Harris, Vincent G.; Vittoria, Carmine

2005-05-01

286

Low activation ferritic alloys  

DOEpatents

Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

1985-02-07

287

Synthesis and charcterization of Nanocrystalline NiCuZn Ferrite prepared by Sol-gel auto combution method  

NASA Astrophysics Data System (ADS)

Promising future applications of ferrite nanoparticles in medicine, making many devices like permanent magnets, memory storage devices etc. Ferrite nanoparticles have been the emerging focus of the recent scientific research. Therefore nanostructured powders of ferrites having chemical compositions [Ni0.8-xCu0.2Znxfe2O4], where x=0.3, 0.5, synthesised through nitrate citrate by sol-gel autocombustion method from stoichiometric mixture of their respective metal nitrate. The prepared powders were sintered at 400 0C and 600 0C for 4 hours. The structural, morphology, ferrite formation of powder were determined by X-ray powder diffractometry (XRD), Scanning Electron Microscope (SEM) photograph of the samples and Infrared (IR) spectroscopy technique. The X-ray revealed the formation of nano-sized ferrite particles with cubic spinel structure and the cubic phase in the ferrite matrix. The IR shows the characteristic ferrite bonds were confirmed. The average crystalline particles sized were calculated by Scherrer formula. The average crystalline size obtained from XRD was found between 40 and 44nm. The lattice parameters, X-ray density and bond length are different parameters are calculated from XRD patterns. The UV-Visible Spectroscopy of prepared sample shows that the band gap energy in the range of semiconductor materials. The Coercivity was found to change in proportionally and sintering temperature with the particle sizes of the investigated ferrites.

Rathod, Sopan M.; Shinde, Ashok B.

2012-11-01

288

Thermo-Responsive Mn–Zn Ferrite\\/Poly(N,N?Isopropyl Acrylamide-co-N-Hydroxymethylacrylamide) Core\\/Shell Nanocomposites for Drug-Delivery Systems  

Microsoft Academic Search

A kind of thermo-sensitive core\\/shell nanoparticles (Mn–Zn ferrite\\/poly(N,N?-isopropylacrylamide-co-N-hydroxymethylacrylamide)) has been designed in this work. By using the surface initiated method, a thermoresponsive co-polymer composed of N,N?-isopropylacrylamide (NIPAAm) and N-hydroxymethylacrylamide (HMAAm) was grafted from ferrite core. The nanoparticles obtained were characterized by FT-IR, XRD, TGA, HRTEM and DLS. The HRTEM observation showed a clear contrast between an ordered crystalline core and

Cao Yang; Ren Jie; Li Jianbo; Liu Yan

2011-01-01

289

Occupational exposure to manganese.  

PubMed Central

The relationship between the degree of exposure and biological effects of manganese was studied in a group of 369 workers employed in the production of ferroalloys. Two other groups of workers, from an electrode plant and from an aluminium rolling mill, served as controls. Mean manganese concentrations at work places where ferroalloys were produced varied from 0-301 to 20-442 mg/m3. The exposure level of the two control groups was from 2 to 30 microgram/m3 and from 0-05 to 0-07 microgram/m3, in the electrode plant and rolling mill respectively. Sixty-two (16-8%) manganese alloy workers showed some signs of neurological impairment. These signs were noticeably less in the two control groups (5-8% and 0%) than in the occupationally exposed group. Subjective symptoms, which are nonspecific but may be symptoms of subclinical manganism, were not markedly different in the three groups. However, in the manganese alloy workers some of the subjective symptoms occurred more frequently in heavier smokers than in light smokers or nonsmokers. Heavier smokers engaged in manganese alloy production showed some of the subjective symptoms more often than heavier smokers from the control groups.

Saric, M; Markicevic, A; Hrustic, O

1977-01-01

290

Manganese biomining: A review.  

PubMed

Biomining comprises of processing and extraction of metal from their ores and concentrates using microbial techniques. Currently this is used by the mining industry to extract copper, uranium and gold from low grade ores but not for low grade manganese ore in industrial scale. The study of microbial genomes, metabolites and regulatory pathways provide novel insights to the metabolism of bioleaching microorganisms and their synergistic action during bioleaching operations. This will promote understanding of the universal regulatory responses that the biomining microbial community uses to adapt to their changing environment leading to high metal recovery. Possibility exists of findings ways to imitate the entire process during industrial manganese biomining endeavor. This paper reviews the current status of manganese biomining research operations around the world, identifies factors that drive the selection of biomining as a processing technology, describes challenges in exploiting these innovations, and concludes with a discussion of Mn biomining's future. PMID:21632238

Das, A P; Sukla, L B; Pradhan, N; Nayak, S

2011-08-01

291

High power ferrite microwave switch  

Microsoft Academic Search

A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out

I. Bardash; N. K. Roschak

1975-01-01

292

Enhanced water electrolysis: Electrocatalytic generation of oxygen gas at manganese oxide nanorods modified electrodes  

Microsoft Academic Search

This study is concerned with the electrocatalytic evolution of oxygen gas at manganese oxide nanorods modified Pt, Au and GC electrodes in 0.5M KOH solution. The electrochemical measurements revealed a significant enhancement of the electrocatalytic activity of the Pt, Au and GC electrodes towards the oxygen evolution reaction (OER) upon the electrodeposition of manganese oxide nanoparticles (nano-MnOx), that is, the

Mohamed S. El-Deab; Mohamed I. Awad; Ahmad M. Mohammad; Takeo Ohsaka

2007-01-01

293

Carbon-supported manganese oxide nanocatalysts for rechargeable lithium–air batteries  

Microsoft Academic Search

Manganese oxide based catalysts were synthesised in the form of nano-particles using a redox reaction of MnSO4 and KMnO4, housed into the pores of a carbon matrix and followed by a thermal treatment. Particle sizes of the manganese oxide nanocatalysts were around 50nm, based on the tunnelling electron microscope measurement. They were uniformly distributed in the carbon matrix, which contributed

H. Cheng; K. Scott

2010-01-01

294

Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation  

PubMed Central

Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn3+/Mn4+ ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states.

Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H.; Navrotsky, Alexandra

2013-01-01

295

Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation.  

PubMed

Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H; Navrotsky, Alexandra

2013-05-28

296

Synthesis and characterization of size-controlled cobalt-ferrite-based ionic ferrofluids  

NASA Astrophysics Data System (ADS)

Size-controlled synthesis of cobalt-ferrite nanoparticles, their passivation and peptization as stable ferrofluids are reported. Transmission electron microscopy and Mössbauer spectroscopy were used as characterization techniques. Particles with little change in size distribution, in the 10-15 nm diameter ranges, were obtained using stirring speeds between 2700 and 8100 rpm. The anomalous diffusion has been used to explain the nanoparticle size-control mechanism.

Morais, P. C.; Garg, V. K.; Oliveira, A. C.; Silva, L. P.; Azevedo, R. B.; Silva, A. M. L.; Lima, E. C. D.

2001-01-01

297

Synthesis and characterization of size-controlled cobalt-ferrite-based ionic ferrofluids  

Microsoft Academic Search

Size-controlled synthesis of cobalt-ferrite nanoparticles, their passivation and peptization as stable ferrofluids are reported. Transmission electron microscopy and Mössbauer spectroscopy were used as characterization techniques. Particles with little change in size distribution, in the 10–15nm diameter ranges, were obtained using stirring speeds between 2700 and 8100rpm. The anomalous diffusion has been used to explain the nanoparticle size-control mechanism.

P. C. Morais; V. K. Garg; A. C. Oliveira; L. P. Silva; R. B. Azevedo; A. M. L. Silva; E. C. D. Lima

2001-01-01

298

Probing the Chemical Stability of Mixed Ferrites: Implications for MR Contrast Agent Design.  

PubMed

Nanomaterials with mixed composition, in particular magnetic spinel ferrites, are emerging as efficient contrast agents for magnetic resonance imaging (MRI). Many factors, including size, composition, atomic structure, and surface properties are crucial in the design of such nanoparticle-based probes due to their influence on the magnetic properties. Silica-coated iron oxide (IO-SiO(2)) and cobalt ferrite (CoIO-SiO(2)) nanoparticles were synthesized using standard high temperature thermal decomposition and base-catalyzed water-in-oil microemulsion techniques. Under neutral aqueous conditions, it was found that 50-75% of the cobalt content in the CoIO-SiO(2) nanoparticles leached out of the core structure. Leaching caused a 7.2-fold increase in longitudinal relaxivity and an increase in the saturation magnetization from ~48 emu/g core to ~65 emu/g core. X-ray absorption fine structure studies confirmed that the atomic structure of the ferrite core was altered following leaching, while TEM and DLS confirmed that the morphology and size of the nanoparticle remained unchanged. The CoIO-SiO(2) nanoparticles converted from a partially inverted spinel cation arrangement (unleached state) to an inverse spinel arrangement (leached state). The control IO-SiO(2) nanoparticles remained stable with no change in structure and negligible changes in magnetic behavior. This detailed analysis highlights how important understanding the properties of nanomaterials is in the development of reliable agents for diagnostic and therapeutic applications. PMID:21603070

Schultz-Sikma, Elise A; Joshi, Hrushikesh M; Ma, Qing; Macrenaris, Keith W; Eckermann, Amanda L; Dravid, Vinayak P; Meade, Thomas J

2011-05-24

299

Probing the Chemical Stability of Mixed Ferrites: Implications for MR Contrast Agent Design  

PubMed Central

Nanomaterials with mixed composition, in particular magnetic spinel ferrites, are emerging as efficient contrast agents for magnetic resonance imaging (MRI). Many factors, including size, composition, atomic structure, and surface properties are crucial in the design of such nanoparticle-based probes due to their influence on the magnetic properties. Silica-coated iron oxide (IO-SiO2) and cobalt ferrite (CoIO-SiO2) nanoparticles were synthesized using standard high temperature thermal decomposition and base-catalyzed water-in-oil microemulsion techniques. Under neutral aqueous conditions, it was found that 50–75% of the cobalt content in the CoIO-SiO2 nanoparticles leached out of the core structure. Leaching caused a 7.2-fold increase in longitudinal relaxivity and an increase in the saturation magnetization from ~48 emu/g core to ~65 emu/g core. X-ray absorption fine structure studies confirmed that the atomic structure of the ferrite core was altered following leaching, while TEM and DLS confirmed that the morphology and size of the nanoparticle remained unchanged. The CoIO-SiO2 nanoparticles converted from a partially inverted spinel cation arrangement (unleached state) to an inverse spinel arrangement (leached state). The control IO-SiO2 nanoparticles remained stable with no change in structure and negligible changes in magnetic behavior. This detailed analysis highlights how important understanding the properties of nanomaterials is in the development of reliable agents for diagnostic and therapeutic applications.

Schultz-Sikma, Elise A.; Joshi, Hrushikesh M.; Ma, Qing; MacRenaris, Keith W.; Eckermann, Amanda L.; Dravid, Vinayak P.; Meade, Thomas J.

2011-01-01

300

In vivo investigation of cobalt ferrite-based magnetic fluid and magnetoliposomes using morphological tests  

Microsoft Academic Search

Morphological studies were carried out after endovenous injection of a magnetic fluid and magnetoliposome samples, all containing cobalt ferrite magnetic nanoparticles (MNPs). Twenty four hours after injection, the three investigated samples presented differences concerning blood clearance, phagocytosis susceptibility, and MNP cluster size and amount. Our data suggest that the samples investigated are biocompatible and could be used as material basis

S. Kückelhaus; S. C. Reis; M. F. Carneiro; A. C. Tedesco; D. M. Oliveira; E. C. D. Lima; P. C. Morais; R. B. Azevedo; Z. G. M. Lacava

2004-01-01

301

Hot coal gas desulfurization with manganese-based sorbents  

SciTech Connect

The primary major deposit of manganese in the US which can be readily mined by an in situ process is located in the Emily district of Minnesota. The US Bureau of Mines Research Centers at both the Twin Cities and Salt Lake City have developed a process for extracting and refining manganese in the form of a high-purity carbonate product. This product has been formulated into pellets by a multi-step process of drying, calcination, and induration to produce relatively high-strength formulations which are capable of being used for hot fuel gas desulfurization. These pellets, which have been developed at the University of Minnesota under joint sponsorship of the US Department of Energy and the US Bureau of Mines, appear superior to other, more expensive, formulations of zinc titanate and zinc ferrite which have previously been studied for multi-cycle loading (desulfurization) and regeneration (evolution of high-strength SO{sub 2} and restoration of pellet reactivity). Although these other formulations have been under development for the past twelve years, their prices still exceed $7 per pound. If manganese pellets perform as predicted in fixed bed testing, and if a significant number of utilities which burn high-sulfur coals incorporate combined-cycle gasification with hot coal gas desulfurization as a viable means of increasing conversion efficiencies, then the potential market for manganese pellets may be as high as 200,000 tons per year at a price not less than $3 per pound. This paper discusses the role of manganese pellets in the desulfurization process with respect to the integrated gasification combined-cycle (IGCC) for power generation.

Hepworth, M.T.; Ben-Slimane, R.

1995-11-01

302

Marine manganese tailings concrete: advantages and drawbacks  

Microsoft Academic Search

Korea, India and China are moving ahead with plans to develop a marine manganese nodule industry. This industry or a related manganese crust, hydrothermal manganese or existing terrestrial manganese industry will dispose millions of tons of fine grained manganese waste. This disposal presents a significant environmental liability. An ideal solution would be to use this material for a beneficial purpose.

John C. Wiltshire; Kathleen A. Moore

1999-01-01

303

21 CFR 582.5446 - Manganese chloride.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Manganese chloride. 582.5446 Section 582.5446 Food...Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use. This...

2013-04-01

304

Epitaxial Garnets and Hexagonal Ferrites.  

National Technical Information Service (NTIS)

The objective of this research is to develop new and improved epitaxial ferrite materials for use in microwave and millimeter-wave signal processing devices. The major emphasis has been on multiple layer magnetic garnet structures for magnetostatic wave (...

H. L. Glass L. R. Adkins

1983-01-01

305

Carbothermal reduction of zinc ferrite  

Microsoft Academic Search

The carbothermal reduction of zinc ferrite was studied using X-ray diffractometer (XRD), wet chemical analysis, scanning electron\\u000a microscope (SEM), surface area meter, and thermogravimetrical analysis (TGA) systems. Zinc ferrite was found to be decomposed\\u000a to ZnO and Fe2O3 initially and carbothermal reduction of ZnO and Fe2O3 took place simultaneously. The results of the surface area measurement indicated that the surface

Jyh-Jen Lee; Chun-I Lin; Hsi-Kuei Chen

2001-01-01

306

Bacteriology of Manganese Nodules  

PubMed Central

A cell-free extract from Arthrobacter 37, isolated from a manganese nodule from the Atlantic Ocean, exhibited enzymatic activity which accelerated manganese accretion to synthetic Mn-Fe oxide as well as to crushed manganese nodule. The reaction required oxygen and was inhibited by HgCl2 and p-chloromercuribenzoate but not by Atebrine dihydrochloride. The rate of enzymatic action depended on the concentration of cell-free extract used. The enzymatic activity had a temperature optimum around 17.5 C and was destroyed by heating at 100 C. The amount of heat required for inactivation depended on the amount of nucleic acid in the preparation. In the cell-free extract, unlike the whole-cell preparation, peptone could not substitute for NaHCO3 in the reaction mixture. An enzyme-containing protein fraction and a nucleic acid fraction could be separated from cell extract by gel filtration, when prepared in 3% NaCl but not in seawater. The nucleic acid fraction was not required for enzymatic activity.

Ehrlich, H. L.

1968-01-01

307

Synthesis and characterizations of ferrite nanomaterials for phenyl hydrazine chemical sensor applications.  

PubMed

This paper presents the synthesis, characterization and phenyl hydrazine chemical sensing applications of Cd0.5Mg0.5Fe2O4 ferrite nanoparticles. The nanoparticles were synthesized by facile and simple co-precipitation method and characterized in detail in terms of their morphological, structural, compositional and electrical properties. The detailed characterization studies revealed that the prepared nanoparticles are grown in high density, possessing Cd0.5Mg0.5Fe2O4 composition and exhibiting spinel cubic structure. Moreover, the prepared Cd0.5Mg0.5Fe2O4 ferrite nanoparticles were used as efficient electron mediators for the fabrication of high-sensitive, robust, reliable and reproducible phenyl hydrazine chemical sensor by simple I-V technique. The fabricated chemical sensor exhibits a highsensitivity of 7.01 microA mM(-1) cm(-2) with an experimental detection limit of 3.125 mM in a short response time of -10.0 s. This work demonstrates that Cd0.5Mg0.5Fe2O4 ferrite nanoparticles can efficiently be utilized for the fabrication of highly sensitive and reliable chemical sensors. PMID:24734630

Al-Heniti, S H; Umar, Ahmad; Zaki, H M; Dar, G N; Al-Ghamdi, A A; Kim, S H

2014-05-01

308

Ferrite attenuator modulation improves antenna performance  

NASA Technical Reports Server (NTRS)

Ferrite attenuator inserted into appropriate waveguide reduces the gain of the antenna element which is causing interference. Modulating the ferrite attenuator to change the antenna gain at the receive frequency permits ground tracking until the antenna is no longer needed.

Hooks, J. C.; Larson, S. G.; Shorkley, F. H.; Williams, B. T.

1970-01-01

309

Rapidly reversible redox transformation in nanophase manganese oxides at room temperature triggered by changes in hydration.  

PubMed

Chemisorption of water onto anhydrous nanophase manganese oxide surfaces promotes rapidly reversible redox phase changes as confirmed by calorimetry, X-ray diffraction, and titration for manganese average oxidation state. Surface reduction of bixbyite (Mn2O3) to hausmannite (Mn3O4) occurs in nanoparticles under conditions where no such reactions are seen or expected on grounds of bulk thermodynamics in coarse-grained materials. Additionally, transformation does not occur on nanosurfaces passivated by at least 2% coverage of what is likely an amorphous manganese oxide layer. The transformation is due to thermodynamic control arising from differences in surface energies of the two phases (Mn2O3 and Mn3O4) under wet and dry conditions. Such reversible and rapid transformation near room temperature may affect the behavior of manganese oxides in technological applications and in geologic and environmental settings. PMID:24733903

Birkner, Nancy; Navrotsky, Alexandra

2014-04-29

310

Effect of ferrite on cast stainless steels  

SciTech Connect

Premature failure of stainless steel castings in bleach washing service is attributed to poor casting quality high porosity and to a high ferrite content, which makes the castings susceptible to corrosion by hot acid chloride solutions. A survey of the chemical compositions and ferrite contents of corrosion-resistant castings in bleach plants at three pulp mills found high [delta]-ferrite levels in the austenitic matrix due to the improper balance between austenite and ferrite stabilizers.

Nadezhdin, A.; Cooper, K. (Noranda Technology Centre, Pointe Claire, Quebec (Canada)); Timbers, G. (James Maclaren Inc., Quebec (Canada). Kraft Pulp Division)

1994-09-01

311

Microwave Properties of Partially Magnetized Ferrites  

Microsoft Academic Search

With the surge of design activity of ferrite components for phased array RADARs, a knowledge of the microwave characteristics of partially magnetized ferrites is a very useful asset. Phase shifters, circulators, and switches are most economically designed if the biasing field can be kept small. A preferred configuration consists of the microwave ferrite being latched into a major or minor

J. J. Green; F. Sandy; C. E. Patton

1971-01-01

312

High power ferrite microwave switch  

NASA Technical Reports Server (NTRS)

A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

Bardash, I.; Roschak, N. K.

1975-01-01

313

Structural studies with the use of XRD and Mössbauer spectroscopy of new high Manganese steels  

NASA Astrophysics Data System (ADS)

New high-strength austenitic and austenitic-ferritic manganese steels represent a significant potential in applications for structural components in the automotive and railway industry due to the excellent combination of high mechanical properties and good plasticity. They belong to the group of steels called AHSS (Advanced High Strength Steels) and UHSS (Ultra High Strength Steels). Application of this combination of properties allows a reduction in the weight of vehicles by the use of reduced cross-section components, and thus to reduce fuel consumption. The development and implementation of industrial production of such interesting and promising steel and its use as construction material requires an improvement of their casting properties and susceptibility to deformation in plastic working conditions. In this work, XRD, Transmission Mössbauer Spectroscopy and Conversion Electron Mössbauer Spectroscopy were employed in a study of the new high-manganese steels with a austenite and austenite-ferrite structure. The influence of the plastic deformation parameters on the changes in the structure, distribution of ferrite and disclosure of the presence of carbides was determined. The analysis of phase transformations in various times using CEMS method made possible to reveal their fine details.

Jablonska, Magdalena Barbara

2014-04-01

314

Tuning of magnetic properties in cobalt ferrite by varying Fe+2 and Co+2 molar ratios  

NASA Astrophysics Data System (ADS)

Different grades of magnetic cobalt ferrite (CoFe2O4) nanoparticles were synthesized with various molar ratios of Fe+2 to Co+2 ions in the initial salt solutions by the co-precipitation method. The crystal structure and morphology of the nanoparticles are obtained from X-ray diffraction and transmission electron microscopy studies. Fourier transform infrared spectroscopy analysis exhibited the Fe-O stretching vibration ~540 cm-1, confirming the formation of metal oxide. The magnetic studies demonstrate that all of the nanoparticles are superparamagnetic at 300 K. The saturation magnetization and coercivity of the CoFe2O4 nanoparticles are affected by the molar ratios of Fe+2 to Co+2 ions. Among all the synthesized nanoparticles, the system with 75:25 molar ratio of Fe+2 to Co+2 ions with a particle size of 13 nm showed a high magnetization of 90 emu/g.

Biswal, Dipti; Peeples, Brianna N.; Peeples, Caryn; Pradhan, Aswini K.

2013-11-01

315

Harnessing the extracellular bacterial production of nanoscale cobalt ferrite with exploitable magnetic properties.  

PubMed

Nanoscale ferrimagnetic particles have a diverse range of uses from directed cancer therapy and drug delivery systems to magnetic recording media and transducers. Such applications require the production of monodisperse nanoparticles with well-controlled size, composition, and magnetic properties. To fabricate these materials purely using synthetic methods is costly in both environmental and economical terms. However, metal-reducing microorganisms offer an untapped resource to produce these materials. Here, the Fe(III)-reducing bacterium Geobacter sulfurreducens is used to synthesize magnetic iron oxide nanoparticles. A combination of electron microscopy, soft X-ray spectroscopy, and magnetometry techniques was employed to show that this method of biosynthesis results in high yields of crystalline nanoparticles with a narrow size distribution and magnetic properties equal to the best chemically synthesized materials. In particular, it is demonstrated here that cobalt ferrite (CoFe(2)O(4)) nanoparticles with low temperature coercivity approaching 8 kOe and an effective anisotropy constant of ?10(6) erg cm(-3) can be manufactured through this biotechnological route. The dramatic enhancement in the magnetic properties of the nanoparticles by the introduction of high quantities of Co into the spinel structure represents a significant advance over previous biomineralization studies in this area using magnetotactic bacteria. The successful production of nanoparticulate ferrites achieved in this study at high yields could open up the way for the scaled-up industrial manufacture of nanoparticles using environmentally benign methodologies. PMID:19507866

Coker, Victoria S; Telling, Neil D; van der Laan, Gerrit; Pattrick, Richard A D; Pearce, Carolyn I; Arenholz, Elke; Tuna, Floriana; Winpenny, Richard E P; Lloyd, Jonathan R

2009-07-28

316

Tellurium content of marine manganese oxides and other manganese oxides  

USGS Publications Warehouse

Tellurium in amounts ranging from 5 to 125 parts per million was present in all of 12 samples of manganese oxide nodules from the floor of the Pacific and Indian oceans. These samples represent the first recognized points of high tellurium concentration in a sedimentary cycle. The analyses may lend support to the theory that the minor-element content of seafloor manganese nodules is derived from volcanic emanations.

Lakin, H. W.; Thompson, C. E.; Davidson, D. F.

1963-01-01

317

AC Magnetic Field Effects on Mice Treated with Cobalt-Ferrite-Based Magnetoliposome: Citotoxicity and Genotoxicity Tests  

Microsoft Academic Search

The aim of the present study was to investigate in vivo biological effects of cobalt ferrite nanoparticles surface coated with citrate and encapsulated in stealth magnetoliposome (MLPEG). The investigation includes blood and peritoneum cytometry and micronucleus assay, after exposing the animals to the AC magnetic field.

L. S. Barbosa; N. Sadeghiani; A. C. Tedesco; R. B. Azevedo; P. C. Morais; Z. G. Lacava

2006-01-01

318

Hydrogen Reduction of Cobalt Ferrite.  

National Technical Information Service (NTIS)

The kinetics of reduction of cobalt ferrite by hydrogen as a function of reduction temperature and pressure were measured by thermogravimetric analysis. A minimum in the rate as a function of temperature was observed and its cause attributed to the format...

J. R. Porter L. C. De Jonghe

1979-01-01

319

Manganese oxidation model for rivers  

USGS Publications Warehouse

The presence of manganese in natural waters (>0.05 mg/L) degrades water-supply quality. A model was devised to predict the variation of manganese concentrations in river water released from an impoundment with the distance downstream. The model is one-dimensional and was calibrated using dissolved oxygen, biochemical oxygen demand, pH, manganese, and hydraulic data collected in the Duck River, Tennessee. The results indicated that the model can predict manganese levels under various conditions. The model was then applied to the Chattahoochee River, Georgia. Discrepancies between observed and predicted may be due to inadequate pH data, precipitation of sediment particles, unsteady flow conditions in the Chattahoochee River, inaccurate rate expressions for the low pH conditions, or their combinations.

Hess, Glen, W.; Kim, Byung, R.; Roberts, Philip, J. W.

1989-01-01

320

FATE OF METHYLCYCLOPENTADIENYL MANGANESE TRICARBONYL  

EPA Science Inventory

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been proposed as an octane booster for unleaded gasoline; such use could result in ecological and human exposure through surface water and ground water ecosystems. o evaluate the environmental risks from MMT, its environmenta...

321

Rod-shaped polyaniline barium ferrite nanocomposite: preparation, characterization and properties  

NASA Astrophysics Data System (ADS)

Rod-shaped polyaniline (PANI)-barium ferrite nanocomposite was synthesized by in situ polymerization of aniline in the presence of BaFe12O19 nanoparticles with diameters of 60-80 nm. The structure, morphology and properties of the nanocomposite were measured using powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. Different ferrite/PANI ratios were selected in order to study magnetic and conductive properties. The results indicated that there were some interactions between PANI chains and ferrite particles. The saturation magnetization and the coercivity varied with the ferrite content. The conductivity at room temperature decreased from 43.35 to 6.9 × 10-2 S cm-1 when the ferrite content changed from 0 to 50 wt%. The composite has excellent electromagnetic parameters which indicates potential application in high performance adsorbing materials in broadband and high frequency ranges. The polymerization mechanism and interactions in the nanocomposites were also studied.

Li, Yuanxun; Zhang, Huaiwu; Liu, Yingli; Wen, Qiye; Li, Jie

2008-03-01

322

Hybrid ternary rice paper-manganese oxide-carbon nanotube nanocomposites for flexible supercapacitors.  

PubMed

Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two-electrode supercapacitors demonstrated high capacitance (260.2 F g(-1)), energy (9.0 W h kg(-1)), power (59.7 kW kg(-1)), and cycle stability (12% drop after 3000 cycles). In addition, the nanocomposites show good strength and excellent mechanical flexibility, and their capacitance shows negligible changes after bending more than 100 times. These findings suggest that opportunities exist to further explore the rich chemistry of cellulose fibers for innovative energy applications. PMID:24077360

Jiang, Wenchao; Zhang, Kaixi; Wei, Li; Yu, Dingshan; Wei, Jun; Chen, Yuan

2013-11-21

323

Manganese sulfide formation via concomitant microbial manganese oxide and thiosulfate reduction.  

PubMed

The dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1 produced ?-MnS (rambergite) nanoparticles during the concurrent reduction of MnO? and thiosulfate coupled to H? oxidation. To investigate effect of direct microbial reduction of MnO? on MnS formation, two MR-1 mutants defective in outer membrane c-type cytochromes (?mtrC/?omcA and ?mtrC/?omcA/?mtrF) were also used and it was determined that direct reduction of MnO? was dominant relative to chemical reduction by biogenic sulfide generated from thiosulfate reduction. Although bicarbonate was excluded from the medium, incubations of strain MR-1 with lactate as the electron donor produced MnCO? (rhodochrosite) as well as MnS in nearly equivalent amounts as estimated by micro X-ray diffraction (micro-XRD) analysis. It was concluded that carbonate released from lactate metabolism promoted MnCO? formation and that Mn(II) mineralogy was strongly affected by carbonate ions even in the presence of abundant sulfide and weakly alkaline conditions expected to favour the precipitation of MnS. Formation of MnS, as determined by a combination of micro-XRD, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction analyses was consistent with equilibrium speciation modelling predictions. Biogenic manganese sulfide may be a manganese sink in the Mn biogeochemical cycle in select environments such as deep anoxic marine basins within the Baltic Sea. PMID:21951417

Lee, Ji-Hoon; Kennedy, David W; Dohnalkova, Alice; Moore, Dean A; Nachimuthu, Ponnusamy; Reed, Samantha B; Fredrickson, James K

2011-12-01

324

Probing the Chemical Stability of Mixed Ferrites: Implications for Magnetic Resonance Contrast Agent Design  

SciTech Connect

Nanomaterials with mixed composition, in particular magnetic spinel ferrites, are emerging as efficient contrast agents for magnetic resonance imaging. Many factors, including size, composition, atomic structure, and surface properties, are crucial in the design of such nanoparticle-based probes because of their influence on the magnetic properties. Silica-coated iron oxide (IO-SiO{sub 2}) and cobalt ferrite (CoIO-SiO{sub 2}) nanoparticles were synthesized using standard high-temperature thermal decomposition and base-catalyzed water-in-oil microemulsion techniques. Under neutral aqueous conditions, it was found that 50-75% of the cobalt content in the CoIO-SiO{sub 2} nanoparticles leached out of the core structure. Leaching caused a 7.2-fold increase in the longitudinal relaxivity and an increase in the saturation magnetization from {approx}48 to {approx}65 emu/g of the core. X-ray absorption fine structure studies confirmed that the atomic structure of the ferrite core was altered following leaching, while transmission electron microscopy and dynamic light scattering confirmed that the morphology and size of the nanoparticle remained unchanged. The CoIO-SiO{sub 2} nanoparticles converted from a partially inverted spinel cation arrangement (unleached state) to an inverse spinel arrangement (leached state). The control IO-SiO{sub 2} nanoparticles remained stable with no change in the structure and negligible changes in the magnetic behavior. This detailed analysis highlights how important understanding the properties of nanomaterials is in the development of reliable agents for diagnostic and therapeutic applications.

Schultz-Sikma, Elise A.; Joshi, Hrushikesh M.; Ma, Qing; MacRenaris, Keith W.; Eckermann, Amanda L.; Dravid, Vinayak P.; Meade, Thomas J. (NWU)

2011-09-16

325

Cobalt ferrite thin films as anode material for lithium ion batteries  

Microsoft Academic Search

Spinel cobalt ferrite (CoFe2O4) thin films have been fabricated by 355nm reactive pulsed laser deposition on stainless steel substrates. XRD and SEM analyses showed that the CoFe2O4 films exhibited a polycrystalline structure and were composed of nanoparticles with an average size of 80nm. At 1C rate, the initial irreversible capacity of polycrystalline CoFe2O4 film electrode cycled between 0.01 and 3.0V

Yan-Qiu Chu; Zheng-Wen Fu; Qi-Zong Qin

2004-01-01

326

Use of the photoacoustic spectroscopy for surface characterization of nanometer-sized cobalt-ferrite particles  

Microsoft Academic Search

Photoacoustic spectroscopy was used in the investigation of cobalt ferrite nanosized particles (about 5 nm in diameter) surface-uncoated or surface-coated with different species. The surface-coated nanoparticles display well defined photoacoustic features in the wavelength region typical of d-d transitions of the transition element ions. Removal of the surface-coating layer by thermal treatment strongly quenches the photoacoustic feature, probably due to

P. C. Morais; L. B. Silveira; J. G. Santos; A. C. Oliveira; A. L. Tronconi; R. L. Santos; E. C. D. Lima; J. M. Marchetti; A. C. Tedesco

2005-01-01

327

Ferrite Morphology and Variations in Ferrite Content in Austenitic Stainless Steel Welds.  

National Technical Information Service (NTIS)

Four distinct ferrite morphologies have been identified in type 308 stainless steel multipass welds: vermicular, lacy, acicular, and globular. The first three ferrite types are related to transformations following solidification and the fourth is related ...

S. A. David S. E. Hanzelka C. P. Haltom

1981-01-01

328

Electrokinetic properties of PMAA functionalized NiFe2O4 nanoparticles synthesized by thermal plasma route  

NASA Astrophysics Data System (ADS)

The magnetic nickel ferrite (NiFe2O4) nanoparticles with an average size of 30nm were synthesised by Transferred arc DC Thermal Plasma route. The synthesized nickel ferrite nanoparticles were characterized by TEM and FTIR techniques. The synthesized nickel ferrite nanoparticles were further functionalized with PMAA (polymethacrylic acid) by self emulsion polymerization method and subsequently were characterized by FTIR and Zeta Analyzer. The variation of zeta potential with pH was systematically studied for both PMAA functionalized (PNFO) and uncoated nickel ferrite nanoparticles (NFO). The IEP (isoelectric points) for PNFO and NFO was determined from the graph of zeta potential vs pH. It was observed that the IEP for NFO was at 7.20 and for PNFO it was 2.52. The decrease in IEP of PNFO was attributed to the COOH functional group of PMAA.

Bhosale, Shivaji V.; Mhaske, Pravin; Kanhe, N.; Navale, A. B.; Bhoraskar, S. V.; Mathe, V. L.; Bhatt, S. K.

2014-04-01

329

High-Q ferrite-tuned cavity  

SciTech Connect

Rapid cycling proton synchrotrons, such as the proposed LAMPF II accelerator, require approximately 10 MV per turn rf with 17% tuning range near 50 MHz. The traditional approach to ferrite-tuned cavities uses a ferrite which is longitudinally biased (rf magnetic field parallel to bias field). This method leads to unacceptably high losses in the ferrite. At Los Alamos, we are developing a cavity with transverse bias (rf magnetic field perpendicular to the bias field) that makes use of the tensor permeability of the ferrite. Initial tests of a small (10-cm-diam) quarter-wave singly re-entrant cavity tuned by several different ferrites indicate that the losses in the ferrite can be made negligible compared with the losses due to the surface resistivity of the copper cavity.

Carlini, R.D.; Thiessen, H.A.; Potter, J.M.; Earley, L.M.

1983-01-01

330

Development of a monolithic ferrite memory array  

NASA Technical Reports Server (NTRS)

The results of the development and testing of ferrite monolithic memory arrays are presented. This development required the synthesis of ferrite materials having special magnetic and physical characteristics and the development of special processes; (1) for making flexible sheets (laminae) of the ferrite composition, (2) for embedding conductors in ferrite, and (3) bonding ferrite laminae together to form a monolithic structure. Major problems encountered in each of these areas and their solutions are discussed. Twenty-two full-size arrays were fabricated and fired during the development of these processes. The majority of these arrays were tested for their memory characteristics as well as for their physical characteristics and the results are presented. The arrays produced during this program meet the essential goals and demonstrate the feasibility of fabricating monolithic ferrite memory arrays by the processes developed.

Heckler, C. H., Jr.; Bhiwandker, N. C.

1972-01-01

331

Water-Soluble Spinel Ferrites by a Modified Polyol Process as Contrast Agents in MRI  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have recently been very attractive for biomedical applications. In this study, we have synthesized ferrite nanoparticles for application as contrast agents in MRI experiments. Fe3O4 and MnFe2O4 spinel ferrites with a mean size of 11-12 nm, were prepared by a modified polyol route in commercially available polyethylene glycol with molecular weight 600 (PEG-600). The reaction takes place in the presence of water soluble and non-toxic tri-block copolymer known as Pluronic® F-127 (PEO100-PPO65-PEO100). The nanoparticles have saturation magnetization values of 52 and 68 emu/g for MnFe2O4 and Fe3O4, respectively. Both the Fe3O4, and MnFe2O4 nanoparticles make stable solutions in water known as ferrofluids. Preliminary data demonstrated the capability of these nanoparticles to induce imaging contrast in T2 weighted MRI experiments, making these materials suitable for biomedical applications such as medical MRI.

Basina, Georgia; Tzitzios, Vasilis; Niarchos, Dimitris; Li, Wanfeng; Khurshid, Hafsa; Mao, Hui; Hadjipanayis, Costas; Hadjipanayis, George

2010-12-01

332

Water-Soluble Spinel Ferrites by a Modified Polyol Process as Contrast Agents in MRI  

SciTech Connect

Magnetic nanoparticles have recently been very attractive for biomedical applications. In this study, we have synthesized ferrite nanoparticles for application as contrast agents in MRI experiments. Fe{sub 3}O{sub 4} and MnFe{sub 2}O{sub 4} spinel ferrites with a mean size of 11-12 nm, were prepared by a modified polyol route in commercially available polyethylene glycol with molecular weight 600 (PEG-600). The reaction takes place in the presence of water soluble and non-toxic tri-block copolymer known as Pluronic registered F-127 (PEO{sub 100}-PPO{sub 65}-PEO{sub 100}). The nanoparticles have saturation magnetization values of 52 and 68 emu/g for MnFe{sub 2}O{sub 4} and Fe{sub 3}O{sub 4}, respectively. Both the Fe{sub 3}O{sub 4}, and MnFe{sub 2}O{sub 4} nanoparticles make stable solutions in water known as ferrofluids. Preliminary data demonstrated the capability of these nanoparticles to induce imaging contrast in T{sub 2} weighted MRI experiments, making these materials suitable for biomedical applications such as medical MRI.

Basina, Georgia [Institute of Materials Science, N.C.S.R. 'Demokritos' Agia Paraskevi 15310 Athens (Greece); Department of Physics and Astronomy, University of Delaware, DE 19716, Newark (United States); Tzitzios, Vasilis; Niarchos, Dimitris [Institute of Materials Science, N.C.S.R. 'Demokritos' Agia Paraskevi 15310 Athens (Greece); Li Wanfeng; Khurshid, Hafsa; Hadjipanayis, George [Department of Physics and Astronomy, University of Delaware, DE 19716, Newark (United States); Mao Hui [Department of Radiology, Emory University, School of Medicine, GA 30322, Atlanta (United States); Hadjipanayis, Costas [Department of Neurological Surgery, Emory University, School of Medicine, GA 30322, Atlanta (United States)

2010-12-02

333

Hot coal gas desulfurization with manganese-based sorbents. Quarterly report, January--March 1994  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% Al{sub 2},O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc; hence, it is not as likely to undergo zinc-depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron; hence, the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Sixth Report documents progress in pellet testing two leading formulations; namely FORM 4-A and FORM 1-A via thermogravimetric analysis (TGA). The former is a high-purity carbonate-based material, and the latter is ore-based. Also fixed bed testing of formulation FORM 1-A is described. Included with this report is an Appendix which describes the formulations and the loading tests as performed via TGA. A 2-inch fixed-bed reactor is being utilized to subject a bed of FORM 4-A pellets to cyclic loading and regeneration. Preliminary results indicate that FORM 1-A can be loaded to approximately 12 per cent of its weight in sulfur prior to breakthrough up through sixteen cycles of loading and regeneration. The sulfur loading level drops from 18.2% for fresh pellets to 11.8% after the sixteenth cycle; however, there is no significant decrease in pellet sulfur-capacity after the ninth cycle. The kinetics during the loading and regeneration cycles are rapid.

Hepworth, M.T.; Slimane, R.B.

1994-04-01

334

Anechoic chamber having multi-layer electromagnetic wave absorbers of sintered ferrite and ferrite composite membrane  

Microsoft Academic Search

The structure of the multi-layer electromagnetic wave absorber composed of sintered ferrite and ferrite composite membrane is proposed to improve radiowave absorbing characteristics. The absorption characteristics of the multi-layer absorber can be largely extended compared with the single sintered ferrite layer. Moreover, it is shown that the site attenuation characteristics satisfy the FCC standard for 3 m and 10 m

K. Naito; Tetsuya Mizumoto; Michiharu Takahashi; Sumio Kunieda

1994-01-01

335

Ferrite Treatment of Actinide Waste Solutions: Alternative Methods of Ferrite Production for Use in Waste Treatment.  

National Technical Information Service (NTIS)

Two alternative sources of ferrite for use in actinide removal from process waste solutions at Rocky Flats were investigated to simplify the ferrite process for plant use. These included the formation of iron ferrite (FeO Fe sub 2 O sub 3 ) by the partial...

T. E. Boyd R. L. Kochen M. Y. Price

1985-01-01

336

Development of High-Manganese Steels.  

National Technical Information Service (NTIS)

Nonmagnetic properties, high toughness and low cost are the principal characteristics of high-manganese austenitic steels. Taking advantage of these characteristics, three different types of high-manganese austenitic steels suited for different applicatio...

H. Masumoto H. Yoshimura T. Akasawa S. Ohba T. Harada

1983-01-01

337

Irradiation effects in ferritic steels  

NASA Astrophysics Data System (ADS)

Since 1979 the Alloy Development for Irradiation Performance (ADIP) task funded by the US Department of Energy has been studying the 2-12Cr class of ferritic steels to establish the feasibility of using them in fusion reactor first wall/breeding blanket (FW/B) applications. The advantages of ferritic steels include superior swelling resistance, low thermal stresses compared to austenitic stainless steels, attractive mechanical properties up to 600°C. and service histories exceeding 100 000 h. These steels are commonly used in a range of microstructural conditions which include ferritic, martensitic. tempered martensitic, bainitic etc. Throughout this paper where the term "ferritic" is used it should be taken to mean any of these microstructures. The ADIP task is studying several candidate alloy systems including 12Cr-1MoWV (HT-9), modified 9Cr-1MoVNb, and dual-phased steels such as EM-12 and 2 {1}/{4}Cr-Mo. These materials are ferromagnetic (FM), body centered cubic (bcc), and contain chromium additions between 2 and 12 wt% and molybdenum additions usually below 2%. The perceived issues associated with the application of this class of steel to fusion reactors are the increase in the ductile-brittle transition temperature (DBTT) with neutron damage, the compatibility of these steels with liquid metals and solid breeding materials, and their weldability. The ferromagnetic character of these steels can also be important in reactor design. It is the purpose of this paper to review the current understanding of these bcc steels and the effects of irradiation. The major points of discussion will be irradiation-induced or -enhanced dimensional changes such as swelling and creep, mechanical properties such as tensile strength and various measurements of toughness, and activation by neutron interactions with structural materials.

Lechtenberg, Thomas

1985-08-01

338

Manganese pavements on the blake plateau.  

PubMed

Dredge samples and photographs from the Blake Plateau, off the southeast coast of the United States, indicate that a layer of manganese oxide forms pavement that may be continuous over an area af about 5000 square kilometers. The manganese pavement grades into round manganese nodules to the south and east and into phosphate nodules to the west. The Gulf Stream probably maintains a very unusual environment that prohibits deposition of clastic sediment and permits accretion of manganese pavements. PMID:17739590

Pratt, R M; McFarlin, P F

1966-03-01

339

Study of the mechanism of formation of solid solutions of Li-Mn ferrites by the method of contact diffusion pairs  

SciTech Connect

This paper presents the results of studies of the reaction between (Li, Mn)O/sub 1/ + gamma and Fe/sub 2/O/sub 3/ with the same ratio of Li and Mn as in M3VT grade lithium-manganese ferrite with the composition Li/sub 0/. /sub 434/Mn/sub 0/. /sub 132/Fe/sub 2/. /sub 434/0/sub 4/ and a rectangular hysteresis loop. Analysis of the reaction zone forming as a result of annealing of diffusion pairs of crystals (Li, Mn)0/sub 1/ + gamma-Fe/sub 2/O/sub 3/ showed that mass transfer between them occurs as a result of unilateral diffusion of lithium cations and electrons or oxygen ions and lithium ferrite with the spinel structure forms on the Fe/sub 2/O/sub 3/ tablets, while the orthoferrite crystallizes later when lithium enters into the reaction. In the temperature interval studied 700-1000 C the mobility of the manganese ions is much lower than that of lithium ions, and manganese does not enter into the ferrite phase formed.

Bashkirov, L.A.; Kornilova, N.V.; Pan'kov, V.V.; Saksonov, Yu. G.; Tkachenko, V.A.; Zubets, A.V.

1986-03-01

340

Autonomic Function in Manganese Alloy Workers  

Microsoft Academic Search

The observation of orthostatic hypotension in an index case of manganese toxicity lead to this prospective attempt to evaluate cardiovascular autonomic function and cognitive and emotional neurotoxicity in eight manganese alloy welders and machinists. The subjects consisted of a convenience sample consisting of an index case of manganese dementia, his four co-workers in a “frog shop” for gouging, welding, and

William W. Barrington; Carol R. Angle; Nancy K. Willcockson; Marjorie A. Padula; Thomas Korn

1998-01-01

341

Strength correlation with residual ferrite fraction in 9CrODS ferritic steel  

NASA Astrophysics Data System (ADS)

The microstructure and tensile properties at 973 K in 9CrODS steels were investigated with respect to various fractions of the residual ferrite from zero to 47 vol.%. The formation of the residual ferrite was discussed from a balance between a chemical driving force for ? to ? reverse transformation and the oxide particle pinning force, while 0.04 mass% carbon sample could contain an equilibrium ?-ferrite. With increasing volume fraction of the residual ferrite, strength at 973 K increases but ductility decreases, which is attributed to the fact that the residual ferrite is harder than the tempered martensite.

Miyata, R.; Ukai, S.; Wu, X.; Oono, N.; Hayashi, S.; Ohtsuka, S.; Kaito, T.

2013-11-01

342

Biomarkers of Manganese Intoxication  

PubMed Central

Manganese (Mn), upon absorption, is primarily sequestered in tissue and intracellular compartments. For this reason, blood Mn concentration does not always accurately reflect Mn concentration in the targeted tissue, particularly in the brain. The discrepancy between Mn concentrations in tissue or intracellular components means that blood Mn is a poor biomarker of Mn exposure or toxicity under many conditions and that other biomarkers must be established. For group comparisons of active workers, blood Mn has some utility for distinguishing exposed from unexposed subjects, although the large variability in mean values renders it insensitive for discriminating one individual from the rest of the study population. Mn exposure is known to alter iron (Fe) homeostasis. The Mn/Fe ratio (MIR) in plasma or erythrocytes reflects not only steady-state concentrations of Mn or Fe in tested individuals, but also a biological response (altered Fe homeostasis) to Mn exposure. Recent human studies support the potential value for using MIR to distinguish individuals with Mn exposure. Additionally, magnetic resonance imaging (MRI), in combination with noninvasive assessment of ?-aminobutyric acid (GABA) by magnetic resonance spectroscopy (MRS), provides convincing evidence of Mn exposure, even without clinical symptoms of Mn intoxication. For subjects with long-term, low-dose Mn exposure or for those exposed in the past but not the present, neither blood Mn nor MRI provides a confident distinction for Mn exposure or intoxication. While plasma or erythrocyte MIR is more likely a sensitive measure, the cut-off values for MIR among the general population need to be further tested and established. Considering the large accumulation of Mn in bone, developing an X-ray fluorescence spectroscopy or neutron-based spectroscopy method may create yet another novel non-invasive tool for assessing Mn exposure and toxicity.

Zheng, Wei; Fu, Sherleen X.; Dydak, Ulrike; Cowan, Dallas M.

2010-01-01

343

Manganese toxicity upon overexposure  

PubMed Central

Manganese (Mn) is a required element and a metabolic byproduct of the contrast agent mangafodipir trisodium (MnDPDP). The Mn released from MnDPDP is initially sequestered by the liver for first-pass elimination, which allows an enhanced contrast for diagnostic imaging. The administration of intravenous Mn impacts its homeostatic balance in the human body and can lead to toxicity. Human Mn deficiency has been reported in patients on parenteral nutrition and in micronutrient studies. Mn toxicity has been reported through occupational (e.g. welder) and dietary overexposure and is evidenced primarily in the central nervous system, although lung, cardiac, liver, reproductive and fetal toxicity have been noted. Mn neurotoxicity results from an accumulation of the metal in brain tissue and results in a progressive disorder of the extrapyramidal system which is similar to Parkinson's disease. In order for Mn to distribute from blood into brain tissue, it must cross either the blood–brain barrier (BBB) or the blood–cerebrospinal fluid barrier (BCB). Brain import, with no evidence of export, would lead to brain Mn accumulation and neurotoxicity. The mechanism for the neurodegenerative damage specific to select brain regions is not clearly understood. Disturbances in iron homeostasis and the valence state of Mn have been implicated as key factors in contributing to Mn toxicity. Chelation therapy with EDTA and supplementation with levodopa are the current treatment options, which are mildly and transiently efficacious. In conclusion, repeated administration of Mn, or compounds that readily release Mn, may increase the risk of Mn-induced toxicity.

Crossgrove, Janelle; Zheng, Wei

2014-01-01

344

Hot Coal Gas Desulfurization with manganese-based sorbents. Second [quarterly] technical report, December 1, 1992--March 1, 1993  

SciTech Connect

At present, the focus of work being performed on Hot Coal Gas Desulfurization is primarily in the use of zinc ferrite and zinc titanate sorbents; however studies at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E. T. Turkdogan indicate that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a preferable alternative to zinc-based sorbents. A significant domestic source of manganese in Minnesota is being explored for an in situ leach process which has potential for producing large tonnages of solutions which may be ideal for precipitation and recovery of pure manganese as a carbonate in a reactive form. In the current program the following studies will be addressed: Preparation of manganese sorbent pellets and characterization tests on pellets for strength and surface area; analysis of the thermodynamics and kinetics of sulfur removal from hot fuel gases by individual sorbent pellets (loading tests) by thermogravimetric testing; regeneration tests via TGA on individual sorbent pellets by oxidation; and bench-scale testing on sorbent beds in a two-inch diameter reactor. The developed information will be of value to METC in its determination of whether or not a manganese-based regenerable sorbent holds real promise for sulfur cleanup of hot fuel gases. This information is necessary prior to pilot-scale testing leading to commercial development is undertaken.

Hepworth, M.T.

1993-03-01

345

New layered manganese oxide halides.  

PubMed

The first layered manganese(III) oxide chlorides, Sr2MnO3Cl and Sr4Mn3O8-yCl2, have been synthesised; Sr2MnO3Cl adopts a K2NiF4 type structure with sheets of MnO5 square based pyramids linked through oxygen and separated by SrCl layers; it is the end member of a new family of Ruddlesden-Popper type manganese oxide halides which includes the three-layer member Sr4Mn3O8-yCl2 also reported herein. PMID:12120392

Knee, Christopher S; Weller, Mark T

2002-02-01

346

Nanocrystalline transition metal ferrites: Synthesis, characterization and surface functionalization  

NASA Astrophysics Data System (ADS)

In this thesis, a new synthetic methodology for the high yield synthesis of spinel-type transition metal ferrite nanoparticles has been developed. This approach is based on the complexation of the first-row transition metal cations with diethylene glycol (DEG) followed by the hydrolysis of the resulting chelate iron alkoxide complexes in the presence of an alkaline hydroxide. Due to the passivation of their surfaces with DEG molecules, the as-prepared nanoparticles are stable against agglomeration and can be easily dispersed in polar protic solvents (water, alcohols, etc.). Alternatively, a postsynthesis passivation with carboxylate ions can render the iron oxide nanocrystals highly dispersible in non-polar solvents. Optimization of the reaction conditions suggested that the size of the nanocrystals could be controlled by changing the complexing strength of the reaction medium. This hypothesis was verified in the case of the Fe3O4 nanoparticles: their sizes vary from 5.7 nm when the reaction is performed in neat diethylene glycol to 16.8 nm in N-methyl diethanolamine (NMDEA), whereas a 1:1 (%wt) mixture of these solvents yields nanocrystals with an average size of and 12.7 nm. A detailed characterization by using a wide variety of techniques, including powder X-Ray diffraction, IR spectroscopy, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and 1H-NMR spectrometry was performed in order to elucidate the composition and the morphology of the variable-sized iron oxide nanoparticles. Both finite size and interparticle interaction effects were identified to influence the magnetic behavior of the oleate-capped nanosized particles. At low temperatures the Fe3O 4 nanocrystals exhibit a ferromagnetic behavior with blocking temperatures which increase with the average particle size, whereas at room temperature, except for the largest nanoparticles, they undergo a superparamagnetic relaxation. We exploited the high surface reactivity of the 10 nm Fe3O 4 nanoparticles to attach 2-3 nm gold grains to their surfaces through a simple, two-step chemically controlled procedure. By chemically bonding bioactive molecules to the attached Au nanoparticles these novel nanoarchitectures open up new opportunities for the implementation of the magnetic nanoparticles as a platform for various applications in the biomedical field.

Caruntu, Daniela

347

Ferritic Steels for French LMFBR Steam Generators.  

National Technical Information Service (NTIS)

Austenitic stainless steels have been widely used in many components of the French LMFBR. Up to now, ferritic steels have not been considered for these components, mainly due to their relatively low creep properties. Some ferritic steels are usable when t...

M. Aubert B. Mathieu P. Petrequin

1983-01-01

348

Fabrication and properties of microwave lithium ferrites  

Microsoft Academic Search

Lithium ferrites are low-cost materials which are attractive for microwave device applications. For a number of years these materials have been prominent in the computer core industry because of excellent temperature performance and the squareness of their hysteresis loops. Previous attempts at exploiting lithium ferrites for microwave applications have met with limited success. Properties which required further improvements were the

PAUL D. BABA; GIL M. ARGENTINA; WILLIAM E. COURTNEY; GERALD F. DIONNE; D. Temme

1972-01-01

349

The evolution of ferrite control components  

Microsoft Academic Search

Ferrite control components are widely used in radar, communication, and electronic warfare systems. Some of these components include junction circulators, isolators, phase and amplitude modulators, switches, phase shifters, magnetically tuned filters, limiters, and duplexers. The paper reviews the progress in ferrite control components during the past 20 years, with special emphasis on junction circulators and phase shifter for phased arrays.

L. R. Whicker; C. W. Young Jr.

1978-01-01

350

Electronic Systems with Ferrite Memory Blocks.  

National Technical Information Service (NTIS)

In modern digital computers, ferrite core memories are generally used as the ready-access storage. Recent advances in ferrite core production make it possible to design memories with an operating cycle of 1 msec or less and a capacity of tens of thousands...

Z. Grochowski J. Szewczyk

1970-01-01

351

Ferrite High-Power Effects in Waveguides  

Microsoft Academic Search

Deterioration of ferrite devices caused by both high power thermal and nonlinear effects are discussed. It is shown that thermal effects can be described, at least qualitatively, by a simple exponential equation. A theoretical maximum power capacity is derived in terms of ferrite configuration parameters. The results of experiments with high peak powers at both S-band and X-band frequencies are

R. S. Mangiaracina; E. Stern

1959-01-01

352

Thermo-responsive Mn-Zn ferrite/poly(N,N'-isopropyl acrylamide-co-N-hydroxymethylacrylamide) core/shell nanocomposites for drug-delivery systems.  

PubMed

A kind of thermo-sensitive core/shell nanoparticles (Mn-Zn ferrite/poly(N,N'-isopropylacrylamide-co-N-hydroxymethylacrylamide)) has been designed in this work. By using the surface initiated method, a thermoresponsive co-polymer composed of N,N'-isopropylacrylamide (NIPAAm) and N-hydroxymethylacrylamide (HMAAm) was grafted from ferrite core. The nanoparticles obtained were characterized by FT-IR, XRD, TGA, HRTEM and DLS. The HRTEM observation showed a clear contrast between an ordered crystalline core and a light amorphous polymeric coating. DLS results confirmed the temperature sensitivity of the nanoparticles. In vitro hyperthermia showed well-controlled self-heating properties, indicating that the nanoparticles could potentially be used as an anticancer drug carrier in the biomedical field. PMID:20626931

Yang, Cao; Jie, Ren; Jianbo, Li; Yan, Liu

2011-01-01

353

Preparation of ferrite-coated MFM cantilevers  

NASA Astrophysics Data System (ADS)

Ferrite-coated magnetic force microscopy (MFM) cantilevers were prepared for the use with a high-frequency MFM (HF-MFM) setup. The ferrite coatings were fabricated by means of radio frequency (RF) magnetron sputtering directly on the Si surface. Two types of ferrites were employed in this study: NiZnFe 2O 4 spinel and Co 2Z-type hexaferrite (Ba 3Co 2Fe 24O 41, BCFO). The typical thickness of the coatings was 50 nm. For comparison, ferrite samples on (1 0 0) and (1 1 1)-oriented Si substrates (analogous to the surfaces of the cantilevers) were prepared. Successful HF-MFM imaging was performed with both types of cantilevers using harddisk writer poles as samples. The HF-MFM images obtained by ferrite-coated cantilevers evidently reveal more details of the magnetic field distribution of the writer poles up to the GHz range than conventional CoCr-coated MFM cantilevers.

Koblischka, M. R.; Kirsch, M.; Wei, J.; Sulzbach, T.; Hartmann, U.

2007-09-01

354

Gas sensing properties of ZnFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

Gas sensing performance of ZnFe2O4 ferrite nanoparticles towards various organic volatile compounds is investigated. A self-combustion of a citrate-gel precursor at ~90 °C in ambient air followed by annealing at 400 °C for 2 h has been explored to prepare a single phase spinel ferrite powder containing granular nanoparticles of average 23 nm diameters. A powder compact measures chemiresistive sensitivity of 59, 51, and 67% for organic vapor-analytes methanol, ethanol, and acetone respectively of 200 ppm at 250 °C. Excellent sensitivity of the granular nanoparticles results due to a large surface area to volume ratio effect.

Misra, Susmita; Ram, S.

2013-06-01

355

Magnetic and ultrasonic studies on stable cobalt ferrite magnetic nanofluid.  

PubMed

Stable cobalt ferrite nanofluids of various concentrations have been prepared through co-precipitation method. Structural and morphological studies of nanoparticles are made with the help of X-ray diffraction technique and Transmission Electron Microscope respectively and it is found that the particles exhibit face centered cubic structure with an average size of 14 nm. The magnetic properties of the nanofluids have been analyzed at room temperature which revealed ferromagnetic behavior and also the very low value of coupling constant which ensures the negligible interparticle interaction in the absence of magnetic field. Ultrasonic investigations have been made for the nanofluids at different temperatures and magnetic fields. The temperature effects are explained with the help of open and close-packed water structure. The inter particle interactions of surface modified CoFe2O4 particles and the cluster formation at higher concentrations are realized through the variations in ultrasonic parameters. PMID:24188514

Nabeel Rashin, M; Hemalatha, J

2014-03-01

356

Self-biased cobalt ferrite nanocomposites for microwave applications  

NASA Astrophysics Data System (ADS)

Oriented CoFe2O4 nanoparticles, dispersed in polymethyl methacrylate (PMMA) matrix, were fabricated by magnetophoretic deposition of functionalized nanocolloidal cobalt ferrite particles into porous alumina membrane. Their magnetic behavior exhibits an out-of-plane easy axis with a large remanent magnetization and coercitivity. This orientation allows high effective internal magnetic anisotropy that contributes to the permanent bias along the wire axis. The microwave studies reveal a ferromagnetic resonance at 46.5 and 49.5 GHz, depending on the filling ratio of the membrane. Ansoft High Frequency Structure Simulator (Ansoft HFSS) simulations are in good agreement with experimental results. Such nanocomposite is presented as one of the promising candidates for microwave devices (circulators, isolators, noise suppressors etc.).

Hannour, Abdelkrim; Vincent, Didier; Kahlouche, Faouzi; Tchangoulian, Ardaches; Neveu, Sophie; Dupuis, Vincent

2014-03-01

357

HRTEM Study of Irradiation-Induced Cavities in Oxide-Dispersed Ferritic Steel  

NASA Astrophysics Data System (ADS)

Structures of oxide nanoparticles and the effects of matrix/nanoparticle interfaces on irradiation-induced cavity nucleation and distribution in Fe-16Cr-4.5Al-0.3Ti-2W-0.37Y2O3 oxide-dispersed ferritic steel have been studied using high-resolution transmission electron microscopy techniques. The frequent observations of partially crystallized complex-oxide nanoparticles in as-fabricated steel provide an implication into the formation mechanism of nanoparticles. The mechanism involves the solid-state mixing of pre-alloyed metallic powder and Y2O3 powder to form an amorphous solid solution and from which the nucleation of high density complex-oxide nanoparticles (on the order of ~1 × 1022 m-3). Simultaneous dual ion beams consisting of iron and helium were employed to irradiate the oxide-dispersed steel at 698 K (425 °C). The result shows that the defective oxide nanoparticles have a positive effect on the mitigation of dimensional swelling as a result of the preferred nucleation of helium-filled cavities at the matrix/nanoparticle interfaces.

Hsiung, Luke L.

2013-10-01

358

Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature.  

PubMed

Magnetic nanoparticles of spinel nanocrystalline cobalt ferrite were synthesized via the sol-gel method and subsequent annealing. The influence of the annealing temperature on the structure, magnetic properties, and magnetorheological effect was investigated. The finite crystallite size of the particles, determined by X-ray diffraction and the particle size observed via transmission electron microscopy, increased with the annealing temperature. The magnetic properties observed via a vibrating sample magnetometer showed that an increase in the annealing temperature leads to the increase in the magnetization saturation and, in contrast, a decrease in the coercivity. The effect of annealing on the magnetic properties of ferrite particles has been explained by the recrystallization process at high temperatures. This resulted in grain size growth and a decrease in an imposed stress relating to defects in the crystal lattice structure of the nanoparticles. The magnetorheological characteristics of suspensions of ferrite particles in silicone oil were measured using a rotational rheometer equipped with a magnetic field generator in both steady shear and small-strain oscillatory regimes. The magnetorheological performance expressed as a relative increase in the magnetoviscosity appeared to be significantly higher for suspensions of particles annealed at 1000 °C. PMID:24668306

Sedlacik, Michal; Pavlinek, Vladimir; Peer, Petra; Filip, Petr

2014-04-01

359

Manganese sulfide formation via concomitant microbial manganese oxide and thiosulfate reduction  

SciTech Connect

The dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1 produced {gamma}-MnS (rambergite) nanoparticles during the concurrent reduction of MnO{sub 2} and thiosulfate coupled to H{sub 2} oxidation. To investigate effect of direct microbial reduction of MnO{sub 2} on MnS formation, two MR-1 mutants defective in outer membrane c-type cytochromes ({Delta}mtrC/{Delta}omcA and {Delta}mtrC/{Delta}omcA/{Delta}mtrF) were also used and it was determined that direct reduction of MnO{sub 2} was dominant relative to chemical reduction by biogenic sulfide generated from thiosulfate reduction. Although bicarbonate was excluded from the medium, incubations of strain MR-1 with lactate as the electron donor produced MnCO{sub 3} (rhodochrosite) as well as MnS in nearly equivalent amounts as estimated by micro X-ray diffraction (micro-XRD) analysis. It was concluded that carbonate released from lactate metabolism promoted MnCO{sub 3} formation and that Mn(II) mineralogy was strongly affected by carbonate ions even in the presence of abundant sulfide and weakly alkaline conditions expected to favor the precipitation of MnS. Formation of MnS, as determined by a combination of micro-XRD, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction analyses was consistent with equilibrium speciation modeling predictions. Biogenic manganese sulfide may be a manganese sink in the Mn biogeochemical cycle in select environments such as deep anoxic marine basins within the Baltic Sea.

Lee, Ji-Hoon; Kennedy, David W.; Dohnalkova, Alice; Moore, Dean A.; Nachimuthu, Ponnusamy; Reed, Samantha B.; Fredrickson, Jim K.

2011-12-13

360

Hydrogen reduction of cobalt ferrite  

SciTech Connect

The kinetics of reduction of cobalt ferrite by hydrogen as a function of reduction temperature and pressure have been measured by thermogravimetric analysis. A minimum in the rate as a function of temperature has been observed and its cause attributed to the formation of a cobalt-wuestite subscale at higher reduction temperatures. A mathematical model, based on one derived by Spitzer, Manning, and Philbrook, has been used to interpret the results in terms of the rate constants for the individual steps in the reaction. Optical microscopy has been used to characterize the morphology of the reduction product and, additionally, partially reduced single crystals of cobalt ferrite have been examined by transmission electron microscopy to characterize the microstructure of the reaction interface. A fine network of pores in the reduced scale was shown to allow the reducing and product gases to reach the immediate vicinity of the chemical reaction. The structure of the porosity and consequently the effective diffusion coefficient in the scale were both shown to be functions of the reduction temperature and pressure. The interface reaction was shown to follow Langmuir-Hinshelwood kinetics. A model was developed to explain such kinetics by incorporating a solid-state diffusion step. Such a step was considered necessary to explain the development of the observed microstructures. An incubation time for the development of a continuous cobalt-wuestite subscale at higher reduction temperatures was attributed to the different growth kinetics for the spinel-metal and spinel-wuestite interfaces.

Porter, J.R.; de Jonghe, L.C.

1981-06-01

361

Über den Einfluß von Wirbelströmen auf die Frequenzabhängigkeit der komplexen Permeabilität hochpermeabler Mangan-Zink-Ferrite  

NASA Astrophysics Data System (ADS)

Nach der Einleitung, in der die Bedeutung der Wirbelströme für den Anstieg der Verluste mit der Frequenz in hochpermeablen Mn-Zn-Ferriten dargelegt wird, werden in Abschn. 2 gemessene Ortskurven der komplexen Permeabilität von Mn-Zn-Ferriten mit Werten der Anfangspermeabilität von 4000 bis 8000 und des spezifischen Widerstandes von 7 bis 138 cm (bei R. T.) vorgestellt. In Abschn. 3 wird der Versuch erläutert, einen gewissen Anfangsteil dieser Ortskurve durch theoretische Wirbelstromortskurven der komplexen Permeabilität, bei denen die Relaxation der komplexen Leitfähigkeit in Form eines von GRANT angegebenen Ausdruckes berücksichtigt ist, wiederzugeben. Die Ergebnisse, die in Abschn. 4 diskutiert werden, erlauben den Schluß, daß die mit der Relaxation der Leitfähigkeit verknüpften kapazitiven Wirbelströme für den Charakter des Anfangsverlaufes der an Ringkernen gemessenen Ortskurven der komplexen Permeabilität von hochpermeablen Mn-Zn-Ferriten bestimmend sein können.Translated AbstractOn the Effect of Eddy Currents on the Magnetic Spectra of High-permeability Manganese-zinc FerritesAfter stressing the importance of eddy currents on the increase of magnetic losses with frequency on high-permeability Mn-Zn-ferrites (in the introduction), experimental curves in the complex plane of the variation of the complex permeability with frequency of Mn-Zn-Ferrites with an initial permeability of 4000 up to 8000 and resistivity of 7 up to 130 ohm . cm are presented in section 2. In section 3 the attempt is stated of reproducing a certain initial part of the curve of complex permeability by theoretical eddy current curves, taking into account the relaxation of complex conductivity in form of an expression given by GRANT. The results discussed in section 4 permit the conclusion, that the capacitive eddy currents due to the relaxation of conductivity may be the essential factor determining the character of the initial turn of the complex magnetic dispersion curve of high-permeability Mn-Zn-ferrites measured on toroidal samples.

Dietzmann, G.; Schaefer, M.

362

Size-selective chemical synthesis of tartrate stabilized cobalt ferrite ionic magnetic fluid.  

PubMed

Ionic magnetic fluid (ferrofluid) is a stable suspension of magnetic nanoparticles in water. Cobalt ferrite nanoparticles are interesting in view of high-density recording storage. The size of the magnetic particles strongly influences the physical properties of the ferrofluids. In this study, we describe the synthesis of ionic magnetic fluid in the presence of tartrate ions. By varying the amount of organic ligands, nanoparticles in a large range of size are obtained: the mean diameter varies from 3 to 10 nm. The effect of tartrate ions on the stability of the ionic magnetic fluid is also studied in relation with the size of the magnetic particles and the amount of adsorbed ligand. PMID:12505076

Neveu, S; Bee, A; Robineau, M; Talbot, D

2002-11-15

363

Effects of irradiation on low activation ferritic alloys: A review  

SciTech Connect

A broad range of ferritic alloys is possible which satisfy the low activation requirement for near-surface burial of fusion reactor materials after decommissioning. Low activation bainitic alloys in the Fe-2Cr composition range, martensitic alloys in the Fe-7 to 9Cr range and stabilized martensitic alloys in the Fe-12Cr range have been successfully fabricated and are undergoing testing as demonstrated by efforts in Europe, Japan and the United States. However, it is found that irradiation significantly degrades the properties of bainitic and stabilized martensitic alloys. Bainitic alloys containing vanadium develop severe hardening due to irradiation-induced precipitation at temperatures below 450/degree/C and extreme softening due to carbide coarsening at temperatures above 500/degree/C. Stabilized martensitic alloys which rely on manganese additions to provide a fully martensitic microstructure are embrittled at grain boundaries following irradiation leading to severe degradation of impact properties. The most promising composition regime appears to be the FE-7 to 9 Cr range with tungsten additions in the 2% range where high temperature mechanical properties and microstructural stability are retained and impact properties are relatively unaffected by irradiation. 25 refs., 9 figs. , 3 tabs.

Gelles, D.S.

1988-03-23

364

Development of ferritic weldments for grain-refined ferritic steels for 4. 2K service  

Microsoft Academic Search

The weldability of grain-refined ferritic nickel steels designed for structural use in liquid helium was investigated. Plates of interstitial-free Fe-12Ni-0.25Ti alloy and carbon-containing 9 Ni steel were welded with 14 Ni ferritic fillers using a gas tungsten arc welding (GTAW) process with pure argon gas shielding. The ferritic weldments made have a strength closely matching those of the base plates

1982-01-01

365

Ferritic steel melt and FLiBe\\/steel experiment : melting ferritic steel  

Microsoft Academic Search

In preparation for developing a Z-pinch IFE power plant, the interaction of ferritic steel with the coolant, FLiBe, must be explored. Sandia National Laboratories Fusion Technology Department was asked to drop molten ferritic steel and FLiBe in a vacuum system and determine the gas byproducts and ability to recycle the steel. We tried various methods of resistive heating of ferritic

Kenneth P. Troncosa; Brandon M. Smith; Tina Joan Tanaka

2004-01-01

366

New barium ferrite particles: Spherical shape  

NASA Astrophysics Data System (ADS)

Pure and ZnTi-doped spherical barium ferrite particles were prepared using two different methods: semicoprecipitation and ultrasonic spray pyrolysis. The ultrasonic spray pyrolysis method was more effective in controlling particle shape. Particle size was in between 0.27 and 0.3 ?m. Coercivity and saturation magnetization were in the range of 1000 to 5000 Oe and 49 to 53 emu/g, respectively. Crystallization of amorphous Ba-Fe-O spherical precursors occurs at a lower temperature than Ba-Fe-Zn-Ti-O precursors. ?M measurement shows that magnetic interaction in spherical barium ferrite tape is weaker than hexagonal platelet barium ferrite.

Hong, Y. K.; Jung, H. S.

1999-04-01

367

A generation of microwave ferrite devices  

NASA Astrophysics Data System (ADS)

The history of the development of microwave ferrite materials and devices is presented together with the theoretical principles used in the modeling of new materials and devices. Developments in materials engineering of garnets and lithium ferrites in the 1960s and 1970s are described together with the evolution of Y-junction circulators and phase shifters. The current levels of performance of Y-circulators and reciprocal and nonreciprocal ferrite latching phase shifters are summarized, and future challenges and trends in the field of millimeter-wave components are outlined.

Rodrigue, G. P.

1988-02-01

368

Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties  

SciTech Connect

In this paper, a simple strategy is developed for rational fabrication of a class of jingle-bell-shaped hollow structured nanomaterials marked as Ag(MFe{sub 2}O{sub 4}) (M=Ni, Co, Mg, Zn), consisting of ferrite hollow shells and metal nanoparticle cores, using highly uniform colloidal Ag(C) microspheres as template. The final composites were obtained by direct adsorption of metal cations Fe{sup 3+} and M{sup 2+} on the surface of the Ag(C) spheres followed by calcination process to remove the middle carbon shell and transform the metal ions into pure phase ferrites. The as-prepared composites were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy and SQUID magnetometer. The results showed that the composites possess the magnetic property of the ferrite shell and the optical together with antibacterial property of the Ag core. - Graphical abstract: MFe{sub 2}O{sub 4} (M=Ni, Co, Mg, Zn) hollow spheres with a noble metal nanoparticle core were successfully prepared by using colloidal metal(C) core-shell spheres as templates with no need of surface modification. The shell thickness and magnetic properties of the ferrite hollow spheres could be controlled by varying the synthetic parameters.

Li Siheng [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Wang Enbo [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)], E-mail: Wangeb889@nenu.edu.cn; Tian Chungui; Mao Baodong; Kang Zhenhui; Li Qiuyu; Sun Guoying [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)

2008-07-15

369

Environmental Controls of Biological Manganese Oxidation  

NASA Astrophysics Data System (ADS)

Biological catalysis of manganese oxidation represents an important contribution to global manganese cycling; biological oxidation rates are several orders of magnitude higher than those of abiotic processes. Despite recent genetics advances, ongoing behavioral studies, and a large pool of knowledge regarding manganese chemistry, the links between biology and environmental chemistry remain unresolved. We have performed experiments on batch cultures of Leptothrix discophora SS-1 to explore the physiology of biological manganese oxidation. We have further conducted spectroscopic and microscopic studies of the mechanism as manganese proceeds from the soluble Mn2+ species to the insoluble Mn(III) and Mn(IV) phases. These investigations suggest roles for aqueous chemistry, mineralogy, and microbial physiology in controlling manganese fluxes in metal-rich environments.

Belz, A. P.; Ahn, C. C.; Nealson, K. H.

2001-12-01

370

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2010-07-01

371

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Barium calcium manganese strontium oxide. 721.10011...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a...chemical substance identified as barium calcium manganese strontium oxide (PMN...

2013-07-01

372

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Barium calcium manganese strontium oxide. ...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. ...The chemical substance identified as barium calcium manganese strontium...

2009-07-01

373

A metal-decorated nickel foam-inducing regulatable manganese dioxide nanosheet array architecture for high-performance supercapacitor applications.  

PubMed

Three dimensional manganese dioxide/Pt/nickel foam (shortened to MnPtNF) hybrid electrodes were prepared by double-pulse polarization and potentiostatic deposition technologies for supercapacitor applications. The decoration of Pt nanoparticles onto nickel foam varies the nucleation mechanism of the manganese dioxide species, inducing the formation of manganese dioxide nanosheets. Additionally, controlling the size of the Pt nanoparticles leads to modulated nanosheet architecture and electrochemical properties of the manganese dioxide electrode, as revealed by XRD, Raman spectra, SEM, TEM, cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The nanosheet architecture of the MnPtNF electrode favors the transportation of electrons and ions, which results in the enhanced electrochemical properties. Importantly, the optimized MnPtNF electrode obtains a maximum specific capacitance of 1222 F g(-1) at 5 A g(-1) (89% of the theoretical specific capacitance of MnO2) and 600 F g(-1) at 100 A g(-1). Moreover, the presence of Pt nanoparticles in the MnO2 electrode effectively improves its cycling stability, which is confirmed by the increase of the specific capacitance retention from 14.7% to 90% after 600 cycles. PMID:23887746

Tang, Peng-Yi; Zhao, Yong-Qing; Wang, Yin-Mei; Xu, Cai-Ling

2013-09-01

374

Magnetic ordering in manganese clusters  

NASA Astrophysics Data System (ADS)

Isolated manganese clusters, Mnn,(n=5-22) are deflected by a linear-gradient magnetic field. Mn7-Mn22 are found to deflect uniformly toward high field. The magnitude of the deflections indicate susceptibilities far in excess of those expected based on the susceptibility of bulk manganese, demonstrating that Mn clusters in this size range are magnetically ordered. Per-atom moments obtained from Curie’s Law analysis range from 0.4?b(Mn19) to 1.7?b(Mn12) . For Mn5 and Mn6 , symmetric broadening of the cluster beam is observed, and their moments were determined via line-shape analysis using both free-spin and adiabatic rotor models. The measured moments, interpreted in light of recent density functional theory calculations, suggest that Mn clusters in this size range are molecular ferrimagnets.

Knickelbein, Mark B.

2004-07-01

375

Effect of antisite formation on magnetic properties of nickel zinc ferrite particles  

NASA Astrophysics Data System (ADS)

In this report, we have investigated the effect of antisite ordering on the magnetic behavior of NiZnFeO4 nanoparticles for x = 0, 0.25, 0.5, 0.75, and 1. Observed magnetization versus temperature data show systematic gradual changes from antiferromagnetic to ferrimagnetic phase with increasing amount of Ni concentration. Saturation magnetization of the parent Zn ferrite increases when substituted by Ni and then decreases for concentration greater than x = 0.5. Coercivity also shows a concentration dependence. Saturation magnetization has no dependence on cooling field at all concentrations. For x = 0.5 the system act as an extremely soft magnetic material with highest saturation magnetization and lowest coercivity. Site occupancy by cations plays an important role for local moment imbalance between different antiferromagnetic sublattices giving rise to ferrimagnetic interaction upon Ni substituted in Zn ferrite.

Ghosh, B.; Sardar, M.; Banerjee, S.

2013-11-01

376

Microstructure and Mechanical Properties of As-Cast Ductile Irons Alloyed with Manganese and Copper  

NASA Astrophysics Data System (ADS)

The present investigation was carried out to study the effect of manganese and copper addition, singly as well as in combination, on the microstructure, micro-segregation, and mechanical properties of ductile irons. Alloy A (3.18C, 2.64Si, 0.45Mn), alloy B (3.35C, 2.51Si, 0.82Mn), alloy C (3.16C, 2.80Si, 1.08Mn, 0.56Cu), and alloy D (3.18C, 3.00Si, 1.04Mn, 1.13Cu) were melted and cast in the form of Y-block test pieces. The cast microstructures varied from ferrito-pearlitic in alloys A, B, and C to pearlitic in alloy D. However, on XRD analysis and SEM examination, the presence of martensite patches was also detected. There was a marginal decrease in nodule count in alloy B. In alloys C and D, nodule counts were higher, but the proportion of ferrite decreased drastically. Alloy D was found to be the strongest (UTS ? 800 MPa, El = 5%) with alloys A and C coming next in strength; while alloy B was weakest of the four. The presence of martensite patches in association with pearlite appears to be responsible for low toughness of these alloys. Microprobe analysis shows some silicon segregation near the graphite nodules and practically little segregation of manganese. Elemental mapping by FE-SEM does not indicate any manganese segregation.

Dasgupta, Ranjan Kumar; Mondal, Dipak Kumar; Chakrabarti, Ajit Kumar; Ganguli, Ashis Chandra

2012-08-01

377

Neurotoxicity of manganese oxide nanomaterials  

Microsoft Academic Search

Manganese (Mn) toxicity in humans has been observed as manganism, a disease that resembles Parkinson’s disease. The mechanism\\u000a of Mn toxicity and the chemical forms that may be responsible for its neurotoxicity are not well understood. We examined the\\u000a toxicity of Mn oxide nanomaterials in a neuronal precursor cell model, using the MTS assay to evaluate mitochondrial function\\u000a in living

Diana M. Stefanescu; Ali Khoshnan; Paul H. Patterson; Janet G. Hering

2009-01-01

378

Weldability of austenitic manganese steel  

Microsoft Academic Search

Hadfield’s manganese steel, nominally Fe–1.2%C–13%Mn, is an alloy of inherent toughness, work-hardening characteristics and excellent resistance to some types of adhesive and abrasive wear. However, due to its low yield strength, it may be deformed markedly before its work-hardening become effective. In certain applications, such as railroad crossings and rock-crushers, this can be a disadvantage. In practice, when this deformation

J. Mendez; M. Ghoreshy; W. B. F. Mackay; T. J. N. Smith; R. W. Smith

2004-01-01

379

Microbial Formation of Manganese Oxides  

PubMed Central

Microbial manganese oxidation was demonstrated at high Mn2+ concentrations (5 g/liter) in bacterial cultures in the presence of a microalga. The structure of the oxide produced varied depending on the bacterial strain and mode of culture. A nonaxenic, acid-tolerant microalga, a Chlamydomonas sp., was found to mediate formation of manganite (?-MnOOH). Bacteria isolated from associations with crude cultures of this alga grown in aerated bioreactors formed disordered ?-MnO2 from Mn2+ at concentrations of 5 g/liter over 1 month, yielding 3.3 g of a semipure oxide per liter. All algal-bacterial cultures removed Mn2+ from solution, but only those with the highest removal rates formed an insoluble oxide. While the alga was an essential component of the reaction, a Pseudomonas sp. was found to be primarily responsible for the formation of a manganese precipitate. Medium components—algal biomass and urea—showed optima at 5.7 and 10 g/liters, respectively. The scaled-up culture (50 times) gave a yield of 22.3 g (53 mg/liter/day from a 15-liter culture) of semipure disordered ?-MnO2, identified by X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy, and had a manganese oxide O/Mn ratio of 1.92. The Mn(IV) content in the oxide was low (30.5%) compared with that of mined or chemically formed ?-MnO2 (ca. 50%). The shortfall in the bacterial oxide manganese content was due to biological and inorganic contaminants. FTIR spectroscopy, transmission electron microscopy, and electron diffraction studies have identified manganite as a likely intermediate product in the formation of disordered ?-MnO2.

Greene, Anthony C.; Madgwick, John C.

1991-01-01

380

Novel 36-membered dodecanuclear manganese metalladiazamacrocycle.  

PubMed

A novel dodecanuclear manganese metalladiazamacrocycle was synthesized employing a new pentadentate ligand N-2-pentenoylsalicylhydrazide (H(3)tpeshz) by supramolecular self-assembly. The backbone of this metal-organic assembly is a repeating unit of an M-N-N-M linkage that extends to complete a 36-membered cyclic structure involving 12 manganese(III) centers. Successive manganese centers are in a chemically different ...ABABAB...-type environment while the chirality varies as ...LambdaLambdaDeltaDeltaLambdaLambda... . The unique arrangement of manganese centers results in a highly puckered metalladiazamacrocycle with an S(6)-point group symmetry. PMID:15568055

John, Rohith P; Lee, Kyungjae; Lah, Myoung Soo

2004-12-01

381

Preparation and magnetic properties of nano size nickel ferrite particles using hydrothermal method  

PubMed Central

Background Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate) on the particles growth is investigated. Methods For investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and inductively coupled plasma atomic emission spectrometer (ICP-AES) techniques were used to characterize the samples. Results The results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature. Conclusions Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of NiFe2O4 nanoparticles decreased in comparison with surfactant- free prepared samples. All of the nickel ferrite nanoparticles were superparamagnetic at room temperature. Graphical abstract

2012-01-01

382

ALL-FERRITE RHIC INJECTION KICKER  

SciTech Connect

Ion beams are transferred from the AGS into RHIC in boxcar fashion as single bunches. The nominal design assumes 60 bunches per ring but increasing the number of bunches to gain luminosity is possible, thereby requiring injection kickers with a shorter rise time. The original injection system consists of traveling-wave dielectric loaded kicker magnets and a Blumlein pulser with a rise time adequate for the present operation. Voltage breakdown in the dielectric kickers suggested the use of all-ferrite magnets. In order to minimize the conversion cost, the design of the all-ferrite kicker uses the same components as the dielectric loaded units. The all-ferrite kickers showed in bench measured good breakdown properties and a current rise time of < 50 ns. A prototype kicker has been installed in the blue ring and was tested with beam. Beam measurements indicate suitability of all-ferrite kicker magnets for upgraded operation.

HAHN,H.; FISCHER,W.; PTITSYN,V.I.; TUOZZOLO,J.E.

2001-06-18

383

Chemically-Deposited Thin Ferrite Films.  

National Technical Information Service (NTIS)

Thin ferrite and garnet films have been prepared by chemically depositing stoichiometric ratios of alcoholic solutions of metal nitrates with divalent and trivalent cations onto ceramic substrates which were then subjected to a firing cycle to form the de...

W. L. Wade T. Collins W. J. Skudera R. Stern

1965-01-01

384

Magnetic micromachines prepared by ferrite plating technique  

NASA Astrophysics Data System (ADS)

By the sterolithography technique and the ferrite plating, we fabricated three types of magnetic micromachines which coated Fe3O4, Co0.39Fe2.61O4, and Co0.45Fe2.55O4, respectively. The stereolithography technique enables one to form the spiral-shape resinous templates and the ferrite plating enables one to coat the ferrites uniformly onto these templates from an aqueous solution. The total machine weight is light because a resin of the template body is almost the same density as water. We verified that the machines swim freely and wirelessly in water by applying a rotational magnetic field. As these machines coated with ferrites have the biocompatibility, there is the possibility of medical microrobots which swim in the human body for medical operations.

Nishimura, K.; Uchida, H.; Inoue, M.; Sendoh, M.; Ishiyama, K.; Arai, K. I.

2003-05-01

385

Synthesis and assembly of high-quality cobalt ferrite nanocrystals prepared by a modified sol–gel technique  

Microsoft Academic Search

Colloidal cobalt ferrite nanocrystals were produced using a new sol–gel-like synthesis based on the procedure developed by O’Brien et al. (J. Am. Chem. Soc. 123 (2001) 12085) for the synthesis of BaTiO3 nanocrystals. This synthesis involves the single-stage high-temperature hydrolysis of the metal alkoxide precursors to obtain crystalline, uniform, organically coated nanoparticles which are well-dispersed in an organic solvent. The

Tal Meron; Yuri Rosenberg; Yossi Lereah; Gil Markovich

2005-01-01

386

Battles with iron: manganese in oxidative stress protection.  

PubMed

The redox-active metal manganese plays a key role in cellular adaptation to oxidative stress. As a cofactor for manganese superoxide dismutase or through formation of non-proteinaceous manganese antioxidants, this metal can combat oxidative damage without deleterious side effects of Fenton chemistry. In either case, the antioxidant properties of manganese are vulnerable to iron. Cellular pools of iron can outcompete manganese for binding to manganese superoxide dismutase, and through Fenton chemistry, iron may counteract the benefits of non-proteinaceous manganese antioxidants. In this minireview, we highlight ways in which cells maximize the efficacy of manganese as an antioxidant in the midst of pro-oxidant iron. PMID:22247543

Aguirre, J Dafhne; Culotta, Valeria C

2012-04-20

387

Sintering behaviour of cobalt ferrite ceramic  

Microsoft Academic Search

Pure cobalt ferrite ceramic powder was prepared using standard solid-state ceramic processing. Uniaxially pressed pure cobalt ferrite discs, sintered under isothermal ramp rate and single dwell time conditions, yielded a maximum theoretical density (%Dth) of <90%. Discs made from finer particle size powder yielded a %Dth of 91.5%. Based on dilatometry analysis, a sintering profile comprising non-isothermal sintering, and two-step

A. Rafferty; T. Prescott; D. Brabazon

2008-01-01

388

Ferrite Elements for Hybrid Microwave Integrated Systems  

Microsoft Academic Search

Complete realization of the potentialities of hybrid microwave integrated circuits will require both semiconductor and ferrite elements. This paper presents performance data for several microstrip ferrite devices that can play an important role in the exploitation of microwave integrated circuits. Data on both fixed-field and latched microstrip junction circulators are given including a fixed-field circulator with less than 0.4-dB loss

J. LAMAR ALLEN; DONALD R. TAFT

1968-01-01

389

A generation of microwave ferrite devices  

Microsoft Academic Search

The history of the development of microwave ferrite materials and devices is presented together with the theoretical principles used in the modeling of new materials and devices. Developments in materials engineering of garnets and lithium ferrites in the 1960s and 1970s are described together with the evolution of Y-junction circulators and phase shifters. The current levels of performance of Y-circulators

G. P. Rodrigue

1988-01-01

390

Ferrite elements for hybrid microwave integrated systems  

Microsoft Academic Search

Complete realization of the potentialities of hybrid microwave integrated circuits will require both semiconductor and ferrite elements. This paper presents performance data for several microstrip ferrite devices that can play an important role in the exploitation of microwave integrated circuits. Data on both fixed-field and latched microstrip junction circulators are given including a fixed-field circulator with less than 0.4- dB

J. L. Allen; D. R. Taft

1968-01-01

391

MÖSSBAUER SPECTROSCOPY ON NICKEL-ZINC FERRITES  

Microsoft Academic Search

The magnetic hyperfine structure of the nickel-zinc ferrite system, ZnxNi1_xFe20i(, have been the subjects of Mossbauer effect studies for many years \\/1-6\\/. It is generally found that the Mossbauer spectra of this material at higher temperature are characterized by the presence of fer­ romagnetic relaxation \\/3-6\\/. Bhargava and Iyengar \\/6\\/ fitted the spectra of Ni-Zn ferrites (with x=0.25, 0.5, 0.75)

T. M. Uen; P. K. Tseng

1979-01-01

392

Hybrid ternary rice paper-manganese oxide-carbon nanotube nanocomposites for flexible supercapacitors  

NASA Astrophysics Data System (ADS)

Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two-electrode supercapacitors demonstrated high capacitance (260.2 F g-1), energy (9.0 W h kg-1), power (59.7 kW kg-1), and cycle stability (12% drop after 3000 cycles). In addition, the nanocomposites show good strength and excellent mechanical flexibility, and their capacitance shows negligible changes after bending more than 100 times. These findings suggest that opportunities exist to further explore the rich chemistry of cellulose fibers for innovative energy applications.Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two-electrode supercapacitors demonstrated high capacitance (260.2 F g-1), energy (9.0 W h kg-1), power (59.7 kW kg-1), and cycle stability (12% drop after 3000 cycles). In addition, the nanocomposites show good strength and excellent mechanical flexibility, and their capacitance shows negligible changes after bending more than 100 times. These findings suggest that opportunities exist to further explore the rich chemistry of cellulose fibers for innovative energy applications. Electronic supplementary information (ESI) available: Chemical structures of functional groups on cellulose fibers, the surface water wettability of rice paper, CV curves of supercapacitors at different scan rates, galvanostatic charge-discharge curves of supercapacitors at different current densities, TGA profiles of the SWCNT-MnO2-paper composites synthesized at different temperatures, TEM images of MnO2 particles deposited on rice paper at different temperatures, photographs of supercapacitors under different bending test conditions, and a video of bending and folding the SWCNT-MnO2-paper composites. See DOI: 10.1039/c3nr03010e

Jiang, Wenchao; Zhang, Kaixi; Wei, Li; Yu, Dingshan; Wei, Jun; Chen, Yuan

2013-10-01

393

Development and application of ferrite materials for low temperature co-fired ceramic technology  

NASA Astrophysics Data System (ADS)

Development and application of ferrite materials for low temperature co-fired ceramic (LTCC) technology are discussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 °C. These ferrite materials are research focuses and are applied in many ways in electronics.

Zhang, Huai-Wu; Li, Jie; Su, Hua; Zhou, Ting-Chuan; Long, Yang; Zheng, Zong-Liang

2013-11-01

394

DNA templated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Recent discoveries in nanoscience are predicted to potentially revolutionize future technologies in an extensive number of fields. These developments are contingent upon discovering new and often unconventional methods to synthesize and control nanoscale components. Nature provides several examples of working nanotechnology such as the use of programmed self assembly to build and deconstruct complex molecular systems. We have adopted a method to control the one dimensional assembly of magnetic nanoparticles using DNA as a scaffold molecule. With this method we have demonstrated the ability to organize 5 nm particles into chains that stretch up to ˜20 mum in length. One advantage of using DNA compared is the ability of the molecule to interact with other biomolecules. After assembling particles onto DNA we have been able to cleave the molecule into smaller fragments using restriction enzymes. Using ligase enzymes we have re-connected these fragments, coated with either gold or iron oxide, to form long one-dimensional arrangements of the two different types of nanoparticles on a single molecular guide. We have also created a sensitive magnetic field sensor by incorporating magnetic nanoparticle coated DNA strands with microfabricated electrodes. The IV characteristics of the aligned nanoparticles are dependant on the magnitude of an externally applied magnetic field. This transport phenomenon known as tunneling magnetoresistance (TMR) shows room temperature resistance of our devices over 80% for cobalt ferrite coated DNA when a field of 20 kOe is applied. In comparison, studies using two dimensional nanoparticle films of irox oxides xii only exhibit a 35% MR effect. Confinement into one dimension using the DNA guide produces a TMR mechanism which produces significant increases in magnetoresistance. This property can be utilized for applications in magnetic field sensing, data storage, and logic elements.

Kinsella, Joseph M.

395

Flash microwave synthesis of trevorite nanoparticles  

SciTech Connect

Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named 'lithium-ion' batteries. In this study, NiFe{sub 2}O{sub 4} was prepared by microwave induced thermohydrolysis. The obtained nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), BET method, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). All the results show that the microwave one-step flash synthesis leads in a very short time to NiFe{sub 2}O{sub 4} nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m{sup 2}/g). Thus, microwave heating appears as an efficient source of energy to produce quickly nanoparticles with complex composition as ferrite. - Graphical abstract: At the end of the 20th century, a new concept of battery was introduced, named 'Li ion', where electrodes are both lithium-storage materials. Compounds with a spinel structure are so investigated and microwave heating appears as an efficient source of energy to produce nanoparticles in a very short time and at low temperature, with controlled size (4-5 nm) and high specific area (240 m{sup 2}/g). Legend: Pictogram represents our original microwave reactor, the RAMO (French acronym of Reacteur Autoclave Micro-Onde), containing the reactants and submitted to the microwave irradiation. Multicolor candy represents obtained material.

Bousquet-Berthelin, C. [NANOSCIENCES-GERM - Groupe d'Etudes et de Recherches en Microondes, I.C.B. (Institut Carnot de Bourgogne), UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, B.P. 47870, 21078 Dijon Cedex (France)], E-mail: christelle.bousquet@u-bourgogne.fr; Chaumont, D.; Stuerga, D. [NANOSCIENCES-GERM - Groupe d'Etudes et de Recherches en Microondes, I.C.B. (Institut Carnot de Bourgogne), UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, B.P. 47870, 21078 Dijon Cedex (France)

2008-03-15

396

Revisiting an old friend: manganese-based MRI contrast agents  

PubMed Central

Non-invasive cellular and molecular imaging techniques are emerging as a multidisciplinary field that offers promise in understanding the components, processes, dynamics and therapies of disease at a molecular level. Magnetic resonance imaging (MRI) is an attractive technique due to the absence of radiation and high spatial resolution which makes it advantageous over techniques involving radioisotopes. Typically paramagnetic and superparamagnetic metals are used as contrast materials for MR based techniques. Gadolinium has been the predominant paramagnetic contrast metal until the discovery and association of the metal with nephrogenic systemic fibrosis (NSF) in some patients with severe renal or kidney disease. Manganese was one of the earliest reported examples of paramagnetic contrast material for MRI because of its efficient positive contrast enhancement. In this review manganese based contrast agent approaches will be presented with a particular emphasis on nanoparticulate agents. We have discussed both classically used small molecule based blood pool contrast agents and recently developed innovative nanoparticle-based strategies highlighting a number of successful molecular imaging examples.

Pan, Dipanjan; Caruthers, Shelton D.; Senpan, Angana; Schmieder, Ann H.; Wickline, Samuel A.; Lanza, Gregory M.

2011-01-01

397

Magneto-resistive coefficient enhancement observed around Verwey-like transition on spinel ferrites XFe2O4 (X = Mn, Zn)  

NASA Astrophysics Data System (ADS)

Manganese and Zinc ferrites were prepared by solid state reaction. The resulting powders were pressed into pellets and heat treated at 1100 °C. The samples were characterized by using X-ray diffraction, pure phases of zinc ferrite (ZnFe2O4) and manganese ferrite (MnFe2O4) were obtained. Scanning electron microscopy images showed a good contact between particles. A drop of electrical resistance was found in both samples, MnFe2O4 and ZnFe2O4, with values going from 2750 to 130 ? and from 1100 to 55 ?, respectively. Transition temperatures were determined to be TV = 225 K for MnFe2O4 and TV = 130 K for ZnFe2O4. Magnetoresistance measurements were carried out in the temperature range where R showed the transition, defined as the Verwey-like transition temperature range, ?TV. No magnetoresistive effect was observed out of it. The magnetoresistive coefficient (MRC) observed at ?TV reached its maximum values of 1.1% for MnFe2O4 and 6.68% for ZnFe2O4. The differences between MRC values are related to the divalent metal element used. Finally, the magnetoresistive response indicates that the electrical transition observed is strongly influencing the magnetoresistance; where the underlying responsible for this behavior could be a charge reordering occurring at the Verwey-like transition temperature.

López Maldonado, K. L.; Vazquez Zubiate, L.; de la Presa, P.; Matutes Aquino, J. A.; Elizalde Galindo, J. T.

2014-05-01

398

Novel magnetic SPE method based on carbon nanotubes filled with cobalt ferrite for the analysis of organochlorine pesticides in honey and tea.  

PubMed

A novel magnetic SPE method based on magnetic cobalt ferrite filled carbon nanotubes (MFCNTs) coupled with GC with electron capture detection was developed to determine organochlorine pesticides (OCPs) in tea and honey samples. The MFCNTs were prepared through the capillarity of carbon nanotubes for drawing mixed cobalt and iron nitrates solution into their inner cavity followed by heating to 550°C under Ar to form the cobalt ferrite nanoparticles. SEM images provided visible evidence of the filled cobalt ferrite nanoparticles in the multiwalled nanotubes. X-ray photoelectron spectroscopy indicated no adhesion of cobalt ferrite nanoparticles and metal salts on the outer surface of the MFCNTs. Eight OCPs were extracted with the MFCNTs. The enrichment factors were in the range of 52-68 for eight OCPs. The LODs for the eight OCPs were in the range of 1.3-3.6 ng/L. The recoveries of the OCPs for honey and tea samples were 83.2-128.7 and 72.6-111.0%, respectively. The RSDs for these samples were below 6.8%. The new method is particularly suited to extract nonpolar and weakly polar analytes from a complex matrix and could potentially be extended to other target analytes. PMID:23926126

Du, Zhuo; Liu, Miao; Li, Gongke

2013-10-01

399

Manganese and Oxidative Damage in Cucumber  

Microsoft Academic Search

Micronutrients in low or high concentration can affect growth, respiration, photosynthesis, and reproduction in plants. Cucumber (Cucumis sativus, L.) is grown in India in areas low or high in manganese concentration in soils. A study was conducted to investigate the effects of manganese concentration on some metabolic activities affecting developmental responses in cucumber. Seed of cucumber, cv. Sonali, were grown

Rajeev Gopal

2008-01-01

400

Splat cooling of aluminium-manganese alloys  

Microsoft Academic Search

The gun technique of splat cooling is utilized to extend the solid solubility of manganese in aluminium by a factor of four above that at the eutectic temperature. The supersaturated solid solutions can be retained up to 250° C without any significant decomposition. Isochronal and isothermal studies of the variation of the lattice parameter of the 6.4 wt % manganese

S. P. Bhat; T. R. Ramachandran; A. K. Jena

1974-01-01

401

Imaging nanoparticle flow using magneto-motive optical Doppler tomography.  

PubMed

We introduce a novel approach for imaging solutions of superparamagnetic iron oxide (SPIO) nanoparticles using magneto-motive optical Doppler tomography (MM-ODT). MM-ODT combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect nanoparticles flowing through a microfluidic channel. A solenoid with a cone-shaped ferrite core extensively increased the magnetic field strength (B(max) = 1 T, [Formula: see text]) at the tip of the core and also focused the magnetic field in microfluidic channels containing nanoparticle solutions. Nanoparticle contrast was demonstrated in a microfluidic channel filled with an SPIO solution by imaging the Doppler frequency shift which was observed independently of the nanoparticle flow rate and direction. Results suggest that MM-ODT may be applied to image Doppler shift of SPIO nanoparticles in microfluidic flows with high contrast. PMID:19636123

Kim, Jeehyun; Oh, Junghwan; Milner, Thomas E; Nelson, J Stuart

2007-01-24

402

Preparation of medical magnetic nanobeads with ferrite particles encapsulated in a polyglycidyl methacrylate (GMA) for bioscreening  

NASA Astrophysics Data System (ADS)

Ferrite nanoparticles (an intermediate between Fe3O4 and ?-Fe2O3), ~7 nm in diameter, were embedded in beads of a mixed polymer of styrene (St) and glycidyl methacrylate (GMA) by emulsifier-free emulsion polymerization method. The beads were coated with GMA by a seeded polymerization method in order to suppress nonspecific protein binding on the surfaces; GMA exhibits very low nonspecific protein binding, which is required for carriers used for bioscreening. The beads have diameters of 180+/-50 nm and saturation magnetizations of 28 emu/g, exceeding commercially available polymer-coated beads of micron size having a weaker saturation magnetization (~12 emu/g).

Nishibiraki, H.; Kuroda, C. S.; Maeda, M.; Matsushita, N.; Abe, M.; Handa, H.

2005-05-01

403

Biological investigation of a citrate-coated cobalt-ferrite-based magnetic fluid  

NASA Astrophysics Data System (ADS)

The present study reports on several in vivo biological tests carried out with a cobalt-ferrite, citrate-coated, magnetic fluid sample developed for biomedical purposes. Systematic biological investigation was performed after endovenous injection in mice. Morphological analysis showed magnetic nanoparticle (MNP) infiltration in the parenchyma or vessels of all investigated organs. Nevertheless, at the investigated dose and period of treatment, no cell damage or inflammatory processes were observed. Cytometry alterations and genotoxic effects were not observed. Although precipitation of MNPs in tissues may be taken as undesirable, the absence of morphological alterations is very promising. The data show that the investigated sample is biocompatible and useful for biomedical applications.

Kückelhaus, S.; Garcia, V. A. P.; Lacava, L. M.; Azevedo, R. B.; Lacava, Z. G. M.; Lima, E. C. D.; Figueiredo, F.; Tedesco, A. C.; Morais, P. C.

2003-05-01

404

Manganese regulates expression of manganese peroxidase by Phanerochaete chrysosporium.  

PubMed Central

The appearance of manganese peroxidase (MnP) activity in nitrogen-limited cultures of Phanerochaete chrysosporium is dependent on the presence of manganese. Cultures grown in the absence of Mn developed normally and produced normal levels of the secondary metabolite veratryl alcohol but produced no MnP activity. Immunoblot analysis indicated that appearance of MnP protein in the extracellular medium was also dependent on the presence of Mn. Intracellular MnP protein was detectable only in cells grown in the presence of Mn. MnP mRNA was detected by Northern (RNA) blot analysis only in cells grown in the presence of Mn. If Mn was added to 4-day-old nitrogen-limited Mn-deficient cultures, extracellular MnP activity appeared after 6 h and reached a maximum after 18 h. Both actinomycin D and cycloheximide inhibited the induction of MnP activity by Mn. These results indicate that Mn, the substrate of the enzyme, is involved in the transcriptional regulation of the MnP gene. Images

Brown, J A; Glenn, J K; Gold, M H

1990-01-01

405

Dinuclear manganese centers in the manganese-lead-tellurate glasses.  

PubMed

FTIR, UV-VIS and EPR spectra of manganese doped lead-tellurate glasses with composition xMnO·(100-x)[4TeO2·PbO2] where x=0, 1, 5, 10, 20, 30, 40mol% have been studied. The FTIR spectra show the formation of the Mn-O-Pb and Mn-O-Te bridging bonds by increasing of MnO concentration. The UV-VIS spectra show the Mn(+3) species exhibit pronounced absorption, which masks the Mn(+2) spin-forbidden absorption bands when Mn(+2) ions are in high concentrations in these glasses. The EPR spectra exhibit resonance signals characteristic of Mn(+2) ions. The resonance signal located at g?2 is due to Mn(+2) ions in an environment close to octahedral symmetry, whereas the resonance at g?4.3 and 3.3 are attributed to the rhombic surroundings of the Mn(+2) ions. The increase in the MnO content gives rise to absorption at g?2.4 and the paramagnetic ions are involved in dinuclear manganese centers. PMID:21498108

Rada, S; Dehelean, A; Culea, M; Culea, E

2011-07-01

406

Dinuclear manganese centers in the manganese-lead-tellurate glasses  

NASA Astrophysics Data System (ADS)

FTIR, UV-VIS and EPR spectra of manganese doped lead-tellurate glasses with composition xMnO·(100 - x)[4TeO 2·PbO 2] where x = 0, 1, 5, 10, 20, 30, 40 mol% have been studied. The FTIR spectra show the formation of the Mn-O-Pb and Mn-O-Te bridging bonds by increasing of MnO concentration. The UV-VIS spectra show the Mn +3 species exhibit pronounced absorption, which masks the Mn +2 spin-forbidden absorption bands when Mn +2 ions are in high concentrations in these glasses. The EPR spectra exhibit resonance signals characteristic of Mn +2 ions. The resonance signal located at g ? 2 is due to Mn +2 ions in an environment close to octahedral symmetry, whereas the resonance at g ? 4.3 and 3.3 are attributed to the rhombic surroundings of the Mn +2 ions. The increase in the MnO content gives rise to absorption at g ? 2.4 and the paramagnetic ions are involved in dinuclear manganese centers.

Rada, S.; Dehelean, A.; Culea, M.; Culea, E.

2011-07-01

407

Measurement of delta Ferrite by Magnetic Saturation Method.  

National Technical Information Service (NTIS)

The magnetic saturation method can be used to determine absolute delta ferrite content of an austenitic weld metal. This report describes an apparatus based on above method that has been developed at Reactor Research Centre. With this apparatus ferrite me...

R. Prabhakar R. D. Kale

1978-01-01

408

Magnetic-Crystallographic Orientation Produced in Ferrites by Hot Working.  

National Technical Information Service (NTIS)

Hot forging of barium cobalt ferrite and barium ferrite gives rise to orientation of the crystallites in a polycrystalline body, with the basal planes of the hexagonal unit cells are aligned perpendicular to the forging direction. Microstructurally the bo...

R. M. Haag

1969-01-01

409

Diclofenac and 2-anilinophenylacetate degradation by combined activity of biogenic manganese oxides and silver.  

PubMed

The occurrence of a range of recalcitrant organic micropollutants in our aquatic environment has led to the development of various tertiary wastewater treatment methods. In this study, biogenic manganese oxides (Bio-MnOx), biogenic silver nanoparticles (Bio-Ag(0)) and ionic silver were used for the oxidative removal of the frequently encountered drug diclofenac and its dechlorinated form, 2-anilinophenylacetate (APA). Diclofenac was rapidly degraded during ongoing manganese oxidation by Pseudomonas putida MnB6. Furthermore, whereas preoxidized Bio-MnOx, Bio-Ag(0) and Ag(+) separately did not show any removal capacity for diclofenac, an enhanced removal occurred when Bio-MnOx and silver species were combined. Similar results were obtained for APA. Finally, a slow removal of diclofenac but more rapid APA degradation was observed when silver was added to manganese-free P. putida biomass. Combining these results, three mechanisms of diclofenac and APA removal could be distinguished: (i) a co-metabolic removal during active Mn(2+) oxidation by P. putida; (ii) a synergistic interaction between preoxidized Bio-MnOx and silver species; and (iii) a (bio)chemical process by biomass enriched with silver catalysts. This paper demonstrates the use of P. putida for water treatment purposes and is the first report of the application of silver combined with biogenic manganese for the removal of organic water contaminants. PMID:22221449

Meerburg, Francis; Hennebel, Tom; Vanhaecke, Lynn; Verstraete, Willy; Boon, Nico

2012-05-01

410

Removal of manganese from water using crushed dolomite filtration technique  

Microsoft Academic Search

This paper discusses manganese removal from water by filtration through low cost coarse media. A laboratory scale filtration technique was used to remove manganese from manganese bearing water to prove previous batch studies which showed that the removal of manganese was better in the case of limestone particle as compared to the gravel, crushed brick or with no media addition,

Hamidi A. Aziz; Paul G. Smith

1996-01-01

411

Iron and manganese removal by using manganese ore constructed wetlands in the reclamation of steel wastewater.  

PubMed

To reclaim treated steel wastewater as cooling water, manganese ore constructed wetland was proposed in this study for the removal of iron and manganese. In lab-scale wetlands, the performance of manganese ore wetland was found to be more stable and excellent than that of conventional gravel constructed wetland. The iron and manganese concentration in the former was below 0.05 mg/L at hydraulic retention time of 2-5 days when their influent concentrations were in the range of 0.16-2.24 mg/L and 0.11-2.23 mg/L, respectively. Moreover, its removals for COD, turbidity, ammonia nitrogen and total phosphorus were 55%, 90%, 67% and 93%, respectively, superior to the corresponding removals in the gravel wetland (31%, 86%, 58% and 78%, respectively). The good performance of manganese ore was ascribed to the enhanced biological manganese removal with the aid of manganese oxide surface and the smaller size of the medium. The presence of biological manganese oxidation was proven by the facts of good manganese removal in wetlands at chemical unfavorable conditions (such as ORP and pH) and the isolation of manganese oxidizing strains from the wetlands. Similar iron and manganese removal was later observed in a pilot-scale gravel-manganese-ore constructed wetland, even though the manganese ore portion in total volume was reduced from 100% (in the lab-scale) to only 4% (in the pilot-scale) for the sake of cost-saving. The quality of the polished wastewater not only satisfied the requirement for cooling water but also suitable as make-up water for other purposes. PMID:19443107

Xu, Jing-Cheng; Chen, Gu; Huang, Xiang-Feng; Li, Guang-Ming; Liu, Jia; Yang, Na; Gao, Sai-Nan

2009-09-30

412

Manganese partitioning in low carbon manganese steel during annealing  

SciTech Connect

For 6Mn16 steel experimental soft annealing at 625 deg. C for periods from 1 h to 60 h and modeling with Thermo-Calc were performed to estimate the partitioning of alloying elements, in particular Mn, between ferrite, cementite and austenite. Using transmission electron microscopy and X-ray analysis it was established that the increase of Mn concentration in carbides to a level 7%-11.2% caused a local decrease of the Ac{sub 1} temperature and led to the presence of austenite around the carbides. Thus, after cooling, small bainite-martensite or bainite-martensite-retained austenite (BM-A) islands were observed. A dispersion of carbides and a coarsening process were observed. The measured amount of Mn in the carbides was in good agreement with theoretical predictions.

Lis, J. [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej, 42-200 Czestochowa (Poland); Lis, A. [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej, 42-200 Czestochowa (Poland)], E-mail: lis@mim.pcz.czest.pl; Kolan, C. [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej, 42-200 Czestochowa (Poland)

2008-08-15

413

Improvement of magnetomechanical properties of cobalt ferrite by magnetic annealing  

Microsoft Academic Search

We report dramatic improvements in both magnetostriction level and strain derivative of polycrystalline cobalt ferrite as a result of magnetic annealing. Magnetostrictive cobalt ferrite composites have potential for use in advanced magnetomechanical stress and torque sensors due to their high sensitivity of magnetization to applied stresses and high levels of magnetostriction. Results show that annealing cobalt ferrite at 300°C in

C. C. H. Lo; A. P. Ring; J. E. Snyder; D. C. Jiles

2005-01-01

414

Neutron Diffraction Observation of Heat Treatment in Cobalt Ferrite  

Microsoft Academic Search

The effect on cobalt ferrite of heat treatment in a magnetic field has been studied by neutron diffraction. The data indicate that the magnetic moments are, in general, displaced from the directions which would be expected from consideration of crystalline anisotropy alone. The effect is greater in ferrites that are iron rich than it is in stoichiometric ferrites. The results

E. Prince

1956-01-01

415

Theory of Linear Ferrite Devices for Microwave Applications  

Microsoft Academic Search

Linear ferrite devices for microwave applications include phase shifters, switches, isolators, circulators, and others whose operation is independent of the applied rf signal level. In this paper, propagation through an infinite ferrite medium is treated first, and points of operation for various ferrite devices are established on a normalized plot of effective permeability vs biasing field. Transfer matrix techniques are

W. H. Von Aulock

1966-01-01

416

Miniature, tunable, and power efficient ferrite phase shifter devices  

Microsoft Academic Search

Ferrite phase shifter devices having drastically reduced bias field requirements are demonstrated at C and Ku band utilizing polycrystalline YIG and single crystal hexagonal Y-type ferrite materials. Phase shifts on the order of 100 degrees with bias fields below 100 Oe are achieved. A novel numerical analysis method for modeling anisotropic ferrites is presented and a good agreement between calculation

A. L. Geiler; J. Wang; I. Viswanathan; S. D. Yoon; J. S. Gao; Y. Chen; C. Vittoria; V. G. Harris

2009-01-01

417

Parameter extraction of ferrite transformers using S-parameters  

Microsoft Academic Search

A characterization of ferrite transformers based on S-parameters measurement using vector network analyzer and specially developed PCB test fixture is presented. Ferrite transformers are realized with commercially available ferrite component. In addition, in order to verify the measurement procedure, we have tested the same component using impedance analyzer, and compared the results with VNA measurement procedure. It is shown that

Mirjana Damnjanovic; Ljiljana Zivanov; Goran Radosavljevic; Andrea Maric; Aleksandar Menicanin

2010-01-01

418

Variations in Weld Ferrite Content Due to P and S.  

National Technical Information Service (NTIS)

It was found that additions of P and S can have a considerable effect on the amount of weld ferrite in Fe-Ni-Cr austenitic alloys. These impurities significantly increased the ferrite content of welds containing primarily the lathy ferrite morphology, but...

J. A. Brooks A. W. Thompson J. C. Williams

1982-01-01

419

Development of high frequency spice models for ferrite core inductors and transformers  

SciTech Connect

In this work high frequency SPICE models were developed to simulate the hysteresis and saturation effects of toroidal shaped ferrite core inductors and transformers. The models include the nonlinear, multi-valued B-H characteristic of the core material, leakage flux, stray capacitances, and core losses. The saturation effects were modeled using two diode clamping arrangements in conjunction with nonlinear dependent sources. Two possible controlling schemes were developed for the saturation switch. One of the arrangements used the current flowing through a series RC branch to control the switch, while the other used a NAND gate. The NAND gate implementation of the switch proved to be simpler and the parameters associated with it were easier to determine from the measurements and the B-H characteristics of the material. Lumped parameters were used to simulate the parasitic effects. Techniques for measuring these parasitic are described. The models were verified using manganese-zinc ferrite-type toroidal cores and they have general applicability to all circuit analysis codes equivalent function blocks such as multipliers, adders, and logic components. 7 refs., 22 figs.

Muyshondt, G.P.; Portnoy, W.M. (Texas Tech Univ., Lubbock, TX (USA). Dept. of Electrical Engineering)

1989-01-01

420

The Manganese Toxicity of Cotton 1  

PubMed Central

Cotton plants (Gossypium hirsutum. Linn. var. Sankar 4) were grown at normal and toxic levels of substrate manganese, and the altered metabolism of manganese toxic plants was studied. The tissues of plants exposed to toxic levels of manganese had higher activities of peroxidase and polyphenol oxidase, and the activities of catalase, ascorbic acid oxidase, glutathione oxidase and cytochrome c oxidase were lowered. In addition, the high manganese tissue had lower contents of ATP and glutathione but higher amounts of ascorbic acid. The respiration of the partially expanded leaves and the growing tips of toxic plants were depressed when compared to that of the normal tissues. The metabolic changes of manganese toxicity of cotton are placed in the following order: accumulation of manganese in the leaf tissue; a rise in respiration; stimulation of polyphenol oxidase; the appearance of initial toxicity symptoms; the evolution of ethylene and stimulation of peroxidase; the presence of severe toxicity symptoms; the depression of terminal oxidases and respiration; abscission of the growing tip and proliferation of the stem tissue. The early stimulation of polyphenol oxidase may be used to detect potential manganese toxicity.

Sirkar, Sheela; Amin, J. V.

1974-01-01