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1

Magnetic, dielectric and sensing properties of manganese substituted copper ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese substituted copper ferrite nanoparticles were synthesized by an auto-combustion technique using metal nitrates and urea for gas sensor application. The products were characterized by XRD, SEM, EDX, TEM and VSM techniques. The effect of annealing temperature on the particle size, magnetic and dielectric properties of Mn-Cu ferrite nanoparticles was analyzed. The size of the particles are in the range of ~9-45 nm. The effect of annealing on the magnetic properties is discussed with the help of variation in saturation magnetization (Ms) and coercivity (Hc) by vibrating sample magnetometer (VSM). The dielectric loss and dielectric constant have been measured in the frequency range of 100 kHz-5 MHz. Furthermore, Conductance response of Mn-Cu ferrite nanomaterial was measured by exposing the material to reducing gas like liquefied petroleum gas (LPG).

Kumar, E. Ranjith; Jayaprakash, R.; Devi, G. Sarala; Reddy, P. Siva Prasada

2014-04-01

2

Biocompatible mesoporous silica-coated superparamagnetic manganese ferrite nanoparticles for targeted drug delivery and MR imaging applications.  

PubMed

Multifunctional mesoporous silica-coated superparamagnetic manganese ferrite (MnFe2O4) nanoparticles (M-MSN) were synthesized and evaluated for targeted drug delivery and magnetic resonance imaging (MRI) applications. MnFe2O4 nanoparticles were prepared by solvothermal route and were silica-coated by surface silylation using sol-gel reactions. Subsequently, silylation was done using (3-aminopropyl)triethoxysilane in presence of a surfactant (CTAB), followed by selective etching of the surfactant molecules that resulted in amine-functionalized superparamagnetic nanoparticles (NH2-MSN). Further modification of the surface of the NH2-MSN with targeting (folate) or fluorescent (RITC) molecules resulted in M-MSN. The formation of the M-MSN was proved by several characterization techniques viz. XRD, XPS, HRTEM, FESEM, VSM, BET surface area measurement, FTIR, and UV-Vis spectroscopy. The M-MSN were loaded with anticancer drug Doxorubicin and the efficacy of the DOX loaded M-MSN was evaluated through in vitro cytotoxicity, fluorescence microscopy, and apoptosis studies. The in vivo biocompatibility of the M-MSN was demonstrated in a mice-model system. Moreover, the M-MSN also acted as superior MRI contrast agent owing to a high magnetization value as well as superparamagnetic behavior at room temperature. These folate-conjugated nanoparticles (FA-MSN) exhibited stronger T2-weighted MRI contrast towards HeLa cells as compared to the nanoparticles without folate conjugation, justifying their potential importance in MRI based diagnosis of cancer. Such M-MSN with a magnetic core required for MRI imaging, a porous shell for carrying drug molecules, a targeting moeity for cancer cell specificity and a fluorescent molecule for imaging, all integrated into a single system, may potentially serve as an excellent material in biomedical applications. PMID:24980623

Sahoo, Banalata; Devi, K Sanjana P; Dutta, Sujan; Maiti, Tapas K; Pramanik, Panchanan; Dhara, Dibakar

2014-10-01

3

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

Code of Federal Regulations, 2011 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...

2011-07-01

4

40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Styrenyl surface treated manganese ferrite (generic). 721.10222...721.10222 Styrenyl surface treated manganese ferrite (generic). (a) Chemical...generically as styrenyl surface treated manganese ferrite (PMN P-09-581) is...

2012-07-01

5

40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Styrenyl surface treated manganese ferrite (generic). 721.10222...721.10222 Styrenyl surface treated manganese ferrite (generic). (a) Chemical...generically as styrenyl surface treated manganese ferrite (PMN P-09-581) is...

2011-07-01

6

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

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Styrenyl surface treated manganese ferrite with acrylic ester polymer...721.10223 Styrenyl surface treated manganese ferrite with acrylic ester polymer...generically as styrenyl surface treated manganese ferrite with acrylic ester...

2012-07-01

7

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Styrenyl surface treated manganese ferrite with acrylic ester polymer...721.10223 Styrenyl surface treated manganese ferrite with acrylic ester polymer...generically as styrenyl surface treated manganese ferrite with acrylic ester...

2013-07-01

8

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

...2014-07-01 false Styrenyl surface treated manganese ferrite with acrylic ester polymer...721.10223 Styrenyl surface treated manganese ferrite with acrylic ester polymer...generically as styrenyl surface treated manganese ferrite with acrylic ester...

2014-07-01

9

40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Styrenyl surface treated manganese ferrite (generic). 721.10222...721.10222 Styrenyl surface treated manganese ferrite (generic). (a) Chemical...generically as styrenyl surface treated manganese ferrite (PMN P-09-581) is...

2013-07-01

10

40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).  

...2014-07-01 false Styrenyl surface treated manganese ferrite (generic). 721.10222...721.10222 Styrenyl surface treated manganese ferrite (generic). (a) Chemical...generically as styrenyl surface treated manganese ferrite (PMN P-09-581) is...

2014-07-01

11

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

12

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

13

Magnetization temperature dependence and freezing of surface spins in magnetic fluids based on ferrite nanoparticles  

Microsoft Academic Search

Manganese and copper ferrite nanoparticles, in the size range 3.3-10.4 nm, are prepared by a hydrothermal coprecipitation process and peptized in aqueous solution. The thermal dependence of the high field magnetization is investigated in the dilute regime and the observed properties can be attributed to individual particles. Our results show that, at low temperatures, the structure of our nanoparticles can

R. Aquino; J. Depeyrot; M. H. Sousa; F. A. Tourinho; E. Dubois; R. Perzynski

2005-01-01

14

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

15

A study of the frequency dependent susceptibility of a colloidal suspension of manganese ferrite (MnFe_20_4) nanoparticles  

Microsoft Academic Search

Measurements of the complex, frequency dependent susceptibility, chi (omega) = chi^{prime} (omega) - i chi^{prime prime} (omega) over the frequency range 50 MHz to 15 GHz, of a surfacted ferrofluid comprising MnFe204 ferrite particles in dibutylphthalat (DBP), as a function of a biasing magnetic field are presented. The biasing field was varied over the range 0 to 100 kAm^{-1}, and

P. C. Fannin; D. Vincent; G. Massart; P. Perov; S. Neveu

1999-01-01

16

Element-and site-specific oxidation state and cation distribution in manganese ferrite films by diffraction anomalous fine structure  

E-print Network

Element- and site-specific oxidation state and cation distribution in manganese ferrite films Received 2 April 2008; accepted 9 July 2008; published online 8 August 2008 Epitaxial manganese ferrite.1063/1.2969406 Spinel ferrites represent an important class of materials that provide high permeability, moderate

Haskel, Daniel

17

Magnetic resonance of ferrite nanoparticles  

Microsoft Academic Search

Ferromagnetic resonance (FMR) experiments at 9.26GHz on non-interacting maghemite (?-Fe2O3) nanoparticles of ferrofluids are performed as a function of temperature (3.5–300K) and particle diameter (4.8–10nm). The orientational mobility of the particles inside the fluid is employed to monitor the orientational distribution of the anisotropy axes by solidifying the MF matrix under the external field. On those textured suspensions, angular analysis

F. Gazeau; J. C Bacri; F. Gendron; R. Perzynski; Yu. L Raikher; V. I. Stepanov; E. Dubois

1998-01-01

18

Optimizing hysteretic power loss of magnetic ferrite nanoparticles  

E-print Network

This thesis seeks to correlate hysteretic power loss of tertiary ferrite nanoparticles in alternating magnetic fields to trends predicted by physical models. By employing integration of hysteresis loops simulated from ...

Chen, Ritchie

2013-01-01

19

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

20

Friction and wear of single-crystal manganese-zinc ferrite  

NASA Technical Reports Server (NTRS)

Sliding friction experiments were conducted with single crystal manganese-zinc ferrite in contact with itself and with transition metals. Results indicate mating highest atomic density directions (110) on matched crystallographic planes exhibit the lowest coefficient of friction, indicating that direction is important in the friction behavior of ferrite. Matched parallel high atomic density planes and crystallographic directions at the interface exhibit low coefficients of friction. The coefficients of friction for ferrite in contact with various metals are related to the relative chemical activity of these metals. The more active the metal, the higher the coefficient of friction. Cracking and the formation of hexagon- and rectangular-shaped platelet wear debris due to cleavages of (110) planes are observed on the ferrite surfaces as a result of sliding.

Miyoshi, K.; Buckley, D. H.

1979-01-01

21

Ionic magnetic fluid based on cobalt ferrite nanoparticles: Influence of hydrothermal treatment on the nanoparticle size  

Microsoft Academic Search

Magnetic fluid based on cobalt ferrite nanoparticles was obtained using a hydrothermal treatment added to the Massart procedure. This treatment increases the average size of the nanoparticles from 11.9 to 18.7nm and also improves the dispersity and crystallinity of the cobalt ferrite particles. The nanoparticles obtained after the hydrothermal treatment were dispersed in aqueous solvent by the classical procedure for

Valérie Cabuil; Vincent Dupuis; Delphine Talbot; Sophie Neveu

2011-01-01

22

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

23

Recycling spent zinc manganese dioxide batteries through synthesizing Zn-Mn ferrite magnetic materials.  

PubMed

A novel process to reclaim spent zinc manganese dioxide batteries (SDBs) through synthesizing Zn-Mn ferrite magnetic materials is present. Firstly, the dismantling, watering, magnetism, baking and griddling steps were consecutively carried out to obtain iron battery shells, zinc grains and manganese compounds using the collected SDBs, and then these separated substances were dissolved with 4 mol L(-1) H(2)SO(4) to prepare FeSO(4), ZnSO(4) and MnSO(4) reactant solutions. Secondly, Zn-Mn ferrites with stoichiometric ratio of Mn(0.26)Zn(0.24)FeO(2) were synthesized using chemical co precipitation process with ammonium oxalate precipitator. The XRD results showed that the obtained Zn-Mn ferrites had spinel structure and high purity at the calcining temperatures of 850-1250 degrees C. With the increase of calcining temperature, the finer crystalline structure could be formed, and their intensity of saturation magnetization reached the highest value at 1150 degrees C. The magnetization performances of Zn-Mn ferrites prepared from the SDBs were similar to that of from analysis reagents, suggesting the feasibility to synthesize Zn-Mn ferrites with high properties from SDBs. PMID:16310946

Nan, Junmin; Han, Dongmei; Cui, Ming; Yang, Minjie; Pan, Linmao

2006-05-20

24

Anisotropic friction and wear of single-crystal manganese-zinc ferrite in contact with itself  

NASA Technical Reports Server (NTRS)

Sliding friction experiments were conducted with manganese-zinc ferrite (100), (110), (111), and (211) planes in contact with themselves. Mating the highest-atomic-density directions, (110), of matched crystallographic planes resulted in the lowest coefficients of friction. Mating matched (same) high-atomic-density planes and matched (same)crystallographic directions resulted in low coefficients of friction. Mating dissimilar crystallographic planes, however, did not give significantly different friction results from those with matched planes. Sliding caused cracking and the formation of hexagonal- and rectangular-platelet wear debris on ferrite surfaces, primarily from cleavage of the (110) planes.

Miyoshi, K.; Buckley, D. H.

1978-01-01

25

Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles  

Microsoft Academic Search

Hydrothermal microwave method (HTMW) was used to synthesize crystalline bismuth ferrite (BiFeO3) nanoparticles (BFO) in the temperature of 180°C with times ranging from 5min to 1h. BFO nanoparticles were characterized by means of X-ray analyses, FT-IR, Raman spectroscopy, TG-DTA and FE-SEM. X-ray diffraction results indicated that longer soaking time was benefit to refraining the formation of any impurity phases and

G. Biasotto; A. Z. Simões; C. R. Foschini; M. A. Zaghete; J. A. Varela; E. Longo

2011-01-01

26

Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses  

PubMed Central

Summary Oriented attachment has created a great debate about the description of crystal growth throughout the last decade. This aggregation-based model has successfully described biomineralization processes as well as forms of inorganic crystal growth, which could not be explained by classical crystal growth theory. Understanding the nanoparticle growth is essential since physical properties, such as the magnetic behavior, are highly dependent on the microstructure, morphology and composition of the inorganic crystals. In this work, the underlying nanoparticle growth of cobalt ferrite nanoparticles in a bioinspired synthesis was studied. Bioinspired syntheses have sparked great interest in recent years due to their ability to influence and alter inorganic crystal growth and therefore tailor properties of nanoparticles. In this synthesis, a short synthetic version of the protein MMS6, involved in nanoparticle formation within magnetotactic bacteria, was used to alter the growth of cobalt ferrite. We demonstrate that the bioinspired nanoparticle growth can be described by the oriented attachment model. The intermediate stages proposed in the theoretical model, including primary-building-block-like substructures as well as mesocrystal-like structures, were observed in HRTEM measurements. These structures display regions of substantial orientation and possess the same shape and size as the resulting discs. An increase in orientation with time was observed in electron diffraction measurements. The change of particle diameter with time agrees with the recently proposed kinetic model for oriented attachment. PMID:24605288

Hetaba, Walid; Wissbrock, Marco; Loffler, Stefan; Mill, Nadine; Eckstadt, Katrin; Dreyer, Axel; Ennen, Inga; Sewald, Norbert; Schattschneider, Peter; Hutten, Andreas

2014-01-01

27

Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles were prepared by a modified sol-gel technique employing coconut oil, and then annealed at different temperatures in 400-1200 °C range. This route of preparation has revealed to be one efficient and cheap technique to obtain high quality nickel ferrite nanosized powder. Sample particles sizes obtained with XRD data and Scherrer's formula lie in 13 nm to 138 nm, with increased size with annealing temperature. Hysteresis loops have been obtained at room temperature with an inductive method. Magnetic field induced microwave absorption in nanoscale ferrites is a recent an active area of research, in order to characterize and explore potential novel applications. In the present work microwave magnetoabsorption data of the annealed nickel ferrite nanoparticles are presented. These data have been obtained with a system based on a network analyzer that operates in the frequency range 0 - 8.5 GHz. At fields up to 400 mT we can observe a peak according to ferromagnetic resonance theory. Sample annealed at higher temperature exhibits different absorption, coercivity and saturation magnetization figures, revealing its multidomain character.

Hernández-Gómez, P.; Muñoz, J. M.; Valente, M. A.; Torres, C.; de Francisco, C.

2013-01-01

28

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

29

Oxidative stress mediated apoptosis induced by nickel ferrite nanoparticles in cultured A549 cells.  

PubMed

Due to the interesting magnetic and electrical properties with good chemical and thermal stabilities, nickel ferrite nanoparticles are being utilized in many applications including magnetic resonance imaging, drug delivery and hyperthermia. Recent studies have shown that nickel ferrite nanoparticles produce cytotoxicity in mammalian cells. However, there is very limited information concerning the toxicity of nickel ferrite nanoparticles at the cellular and molecular level. The aim of this study was to investigate the cytotoxicity, oxidative stress and apoptosis induction by well-characterized nickel ferrite nanoparticles (size 26 nm) in human lung epithelial (A549) cells. Nickel ferrite nanoparticles induced dose-dependent cytotoxicity in A549 cells demonstrated by MTT, NRU and LDH assays. Nickel ferrite nanoparticles were also found to induce oxidative stress evidenced by generation of reactive oxygen species (ROS) and depletion of antioxidant glutathione (GSH). Further, co-treatment with the antioxidant L-ascorbic acid mitigated the ROS generation and GSH depletion due to nickel ferrite nanoparticles suggesting the potential mechanism of oxidative stress. Quantitative real-time PCR analysis demonstrated that following the exposure of A549 cells to nickel ferrite nanoparticles, the level of mRNA expressions of cell cycle checkpoint protein p53 and apoptotic proteins (bax, caspase-3 and caspase-9) were significantly up-regulated, whereas the expression of anti-apoptotic proteins (survivin and bcl-2) were down-regulated. Moreover, activities of caspase-3 and caspase-9 enzymes were also significantly higher in nickel ferrite nanoparticles exposed cells. To the best of our knowledge this is the first report showing that nickel ferrite nanoparticles induced apoptosis in A549 cells through ROS generation and oxidative stress via p53, survivin, bax/bcl-2 and caspase pathways. PMID:21382431

Ahamed, Maqusood; Akhtar, Mohd Javed; Siddiqui, Maqsood A; Ahmad, Javed; Musarrat, Javed; Al-Khedhairy, Abdulaziz A; AlSalhi, Mohamad S; Alrokayan, Salman A

2011-05-10

30

Structural characterization and magnetic properties of superparamagnetic zinc ferrite nanoparticles synthesized by the coprecipitation method  

NASA Astrophysics Data System (ADS)

Single phase zinc ferrite (ZnFe2O4) nanoparticles have been prepared by the coprecipitation method without any subsequent calcination. The effects of precipitation temperature in the range 20-80 °C on the structural and the magnetic properties of zinc ferrite nanoparticles were investigated. The crystallite size, microstructure and magnetic properties of the prepared nanoparticles were studied using X-ray diffraction (XRD), Fourier transmission infrared spectrum, transmission electron microscope (TEM), energy dispersive X-ray spectrometer and vibrating sample magnetometer. The XRD results showed that the coprecipitated nanoparticles were single phase zinc ferrite with mixture of normal and inverse spinel structures. Furthermore, ZnFe2O4 nanoparticles have the crystallite size in the range 5-10 nm, as confirmed by TEM. The magnetic measurements exhibited that the zinc ferrite nanoparticles synthesized at 40 °C were superparamagnetic with the maximum magnetization of 7.3 emu/g at 10 kOe.

Raeisi Shahraki, R.; Ebrahimi, M.; Seyyed Ebrahimi, S. A.; Masoudpanah, S. M.

2012-11-01

31

Magnetic properties of Mg-ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

MgFe 2O 4 nanoparticles encapsulated in amorphous SiO 2 were prepared by means of a wet chemical method, and the magnetic properties were studied. The diameters of these particles were estimated from X-ray diffraction patterns as ranging from 3 to 8 nm. Magnetization measurements were carried out for each sample under a ±50 kOe field. The blocking temperature, Tb, was determined to be around 30 K from the temperature dependence of both the field-cooled (FC) and the zero-field-cooled (ZFC) magnetization. The M- H curve indicated the presence of ferromagnetic behavior with hysteresis below the blocking temperature, Tb. A large coercive force of about 1000 Oe was found at 5 K. Heat treatment was carried out for the prepared samples using an electric furnace in air. A clear difference in magnetization was found between the quenched samples and annealed samples. This phenomenon suggests that the Mg 2+ ions in the spinel structure would be randomly distributed into both the A- and the B-site.

Ichiyanagi, Y.; Kubota, M.; Moritake, S.; Kanazawa, Y.; Yamada, T.; Uehashi, T.

2007-03-01

32

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

33

Probing bismuth ferrite nanoparticles by hard x-ray photoemission: Anomalous occurrence of metallic bismuth  

NASA Astrophysics Data System (ADS)

We have investigated bismuth ferrite nanoparticles (˜75 nm and ˜155 nm) synthesized by a chemical method, using soft X-ray (1253.6 eV) and hard X-ray (3500, 5500, and 7500 eV) photoelectron spectroscopy. This provided an evidence for the variation of chemical state of bismuth in crystalline, phase pure nanoparticles. X-ray photoelectron spectroscopy analysis using Mg K? (1253.6 eV) source showed that iron and bismuth were present in both Fe3+ and Bi3+ valence states as expected for bismuth ferrite. However, hard X-ray photoelectron spectroscopy analysis of the bismuth ferrite nanoparticles using variable photon energies unexpectedly showed the presence of Bi0 valence state below the surface region, indicating that bismuth ferrite nanoparticles are chemically inhomogeneous in the radial direction. Consistently, small-angle X-ray scattering reveals a core-shell structure for these radial inhomogeneous nanoparticles.

Chaturvedi, Smita; Sarkar, Indranil; Shirolkar, Mandar M.; Jeng, U.-Ser; Yeh, Yi-Qi; Rajendra, Ranguwar; Ballav, Nirmalya; Kulkarni, Sulabha

2014-09-01

34

The role of annealing temperature and bio template (egg white) on the structural, morphological and magnetic properties of manganese substituted MFe2O4 (M=Zn, Cu, Ni, Co) nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese substituted ferrites (ZnFe2O4, CuFe2O4, NiFe2O4 and CoFe2O4) have been prepared in the bio template medium by using a simple evaporation method. The annealing temperature plays an important position on changing particle size and morphology of the mixed ferrite nanoparticles were found out by X-ray diffraction, transmission electron microscopy and scanning electron microscopy methods. The role of manganese substitution in the mixed ferrite nanoparticles were also analyzed for different annealing temperature. The substitution of Mn also 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 change and magnetic properties of the mixed ferrite nanoparticles is discussed.

Ranjith Kumar, E.; Jayaprakash, R.; Kumar, Sanjay

2014-02-01

35

Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer BiFeO{sub 3} (BFO) nanoparticles were grown by hydrothermal microwave method (HTMW). Black-Right-Pointing-Pointer The soaking time is effective in improving phase formation. Black-Right-Pointing-Pointer Rietveld refinement reveals an orthorhombic structure. Black-Right-Pointing-Pointer The observed magnetism of the BFO crystallites is a consequence of particle size. Black-Right-Pointing-Pointer The HTMW is a genuine technique for low temperatures and short times of synthesis. -- Abstract: Hydrothermal microwave method (HTMW) was used to synthesize crystalline bismuth ferrite (BiFeO{sub 3}) nanoparticles (BFO) in the temperature of 180 Degree-Sign C with times ranging from 5 min to 1 h. BFO nanoparticles were characterized by means of X-ray analyses, FT-IR, Raman spectroscopy, TG-DTA and FE-SEM. X-ray diffraction results indicated that longer soaking time was benefit to refraining the formation of any impurity phases and growing BFO crystallites into almost single-phase perovskites. Typical FT-IR spectra for BFO nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH{sup -} groups, commonly found in materials obtained by HTMW process. Compared with the conventional solid-state reaction process, submicron BFO crystallites with better homogeneity could be produced at the temperature as low as 180 Degree-Sign C. These results show that the HTMW synthesis route is rapid, cost effective, and could be used as an alternative to obtain BFO nanoparticles in the temperature of 180 Degree-Sign C for 1 h.

Biasotto, G. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)] [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil); Simoes, A.Z., E-mail: alezipo@yahoo.com [Universidade Estadual Paulista-Unesp, Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Pedregulho, CEP 12516-410, Guaratingueta, SP (Brazil); Foschini, C.R.; Zaghete, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)] [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)

2011-12-15

36

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. PMID:24991427

2014-01-01

37

Effects of oleic acid surface coating on the properties of nickel ferrite nanoparticles/PLA composites.  

PubMed

Nickel ferrite nanoparticles with or without oleic acid surface coating were mixed with poly(D,L-lactide) (PLA) by double emulsion method. If the nanoparticles were prepared without oleic acid coating, they adsorbed on the PLA surface. If the nanoparticles were coated with oleic acid, they could be readily encapsulated within the PLA microspheres. A slight depression in glass transition temperature was found in all composites and it could be related to the interfacial energies between nanoparticles and PLA. Optimum mixed composite was achieved by reducing interfacial energy. However, loading capacity was limited in this composite. Increasing the amount of nickel ferrite nanoparticles was not useful to increase loading capacity. Cytotoxicity of the composite decreased significantly when nickel ferrite nanoparticles were effectively encapsulated in PLA microspheres. PMID:18980192

Yin, Hong; Chow, Gan-Moog

2009-11-01

38

Cellular Uptake and Biocompatibility of Bismuth Ferrite Harmonic Advanced Nanoparticles  

E-print Network

Bismuth Ferrite (BFO) nanoparticles (BFO-NP) display interesting optical (nonlinear response) and magnetic properties which make them amenable for bio-oriented applications as intra- and extra membrane contrast agents. Due to the relatively recent availability of this material in well dispersed nanometric form, its biocompatibility was not known to date. In this study, we present a thorough assessment of the effects of in vitro exposure of human adenocarcinoma (A549), lung squamous carcinoma (NCI-H520), and acute monocytic leukemia (THP-1) cell lines to uncoated and poly(ethylene glycol)-coated BFO-NP in the form of cytotoxicity, haemolytic response and biocompatibility. Our results support the attractiveness of the functional-BFO towards biomedical applications focused on advanced diagnostic imaging.

Staedler, Davide; Magouroux, Thibaud; Rogov, Andrii; Maguire, Ciaran Manus; Mohamed, Bashir M; Schwung, Sebastian; Rytz, Daniel; Jüstel, Thomas; Hwu, Stéphanie; Mugnier, Yannick; Dantec, Ronan Le; Volkov, Yuri; Gerber-Lemaire, Sandrine; Prina-Melloc, Adriele; Bonacina, Luigi; Wolf, Jean-Pierre

2014-01-01

39

Exchange bias properties and surface spins freezing in ferrite nanoparticles of magnetic nanocolloids  

Microsoft Academic Search

We investigate magnetic nanocolloids based on 3.3 nm sized particles of manganese ferrite. The observation of shifted hysteresis loops after cooling the sample in high fields indicates the existence of a coupling between the ferrimagnetic ordered core and the disordered surface layer. The exchange bias field, determined from the field offset from the origin, decreases as the cooling field increases.

F. G. Silva; R. Aquino; V. Dupuis; J. Depeyrot; F. A. Tourinho; R. Perzynski

2010-01-01

40

Infield Mossbauer study of disordered surface spins in core\\/shell ferrite nanoparticles  

Microsoft Academic Search

Magnetization and Mossbauer spectroscopy measurements are performed at low temperature under high field, on nanoparticles with a nickel ferrite core and a maghemite shell. These nanoparticles present finite size and surface effects, together with exchange anisotropy. High field magnetization brings the evidences of a monodomain ordered core and surface spins freezing in disorder at low temperature. Mossbauer spectra at 4.2

E. C. Sousa; H. R. Rechenberg; J. Depeyrot; J. A. Gomes; R. Aquino; F. A. Tourinho; V. Dupuis; R. Perzynski

2009-01-01

41

Synthesis and characterization of nickel ferrite magnetic nanoparticles by co-precipitation method  

NASA Astrophysics Data System (ADS)

Magnetic nickel ferrite (NiFe2O4) nanoparticles have been synthesized via co-precipitation method by varying the metal precursors ratio. Four different precursors ratio (Fe:Ni) are varied at 40:60, 50:50, 60:40 and 80:20. The size of the nanoparticles is found to increase with increasing iron (Fe) content. In addition, the morphology of the particles are observed to change from spherical to a shape similar to a nanooctahedral particle when the Fe content in the initial precursors ratio increases. The X-ray Diffraction (XRD) patterns have proved the presence of nickel ferrite nanoparticles. The magnetic properties characterized by Vibrating Sample Magnetometer (VSM) at room temperature proved that the assynthesized nickel ferrite nanoparticles are ferromagnetic and the saturation magnetization (Ms) increases with the content of Fe in the sample.

Ong, B. H.; Chee, E. S. C.; Abd Hamid, S. B. O. A.; Lim, K. P.

2012-11-01

42

Correlation between structural, magnetic, and dielectric properties of manganese substituted cobalt ferrite  

SciTech Connect

Manganese (Mn) substituted cobalt ferrites (CoFe{sub 2?x}Mn{sub x}O{sub 4}, referred to CFMO) were synthesized and their structural, magnetic, and dielectric properties were evaluated. X-ray diffraction measurements coupled with Rietveld refinement indicate that the CFMO materials crystallize in the inverse cubic spinel phase. Temperature (T?=?300?K and 10?K) dependent magnetization (M(H)) measurements indicate the long range ferromagnetic ordering in CoFe{sub 2?x}Mn{sub x}O{sub 4} (x?=?0.00–0.15) ferrites. The cubic anisotropy constant (K{sub 1}(T)) and saturation magnetization (M{sub s}(T)) were derived by using the “law of approach” to saturation that describes the field dependence of M(H) for magnetic fields much higher than the coercive field (H{sub c}). Saturation magnetization (M{sub s}), obtained from the model, decreases with increasing temperature. For CoFe{sub 2}O{sub 4}, M{sub s} decreases from 3.63??{sub B} per formula unit (f.u.) to 3.47??{sub B}/f.u. with increasing temperature from 10 to 300?K. CFMO (0.00–0.15) exhibit the similar trend while the magnitude of M{sub s} is dependent on Mn-concentration. M{sub s}-T functional relationship obeys the Bloch's law. The lattice parameter and magnetic moment calculated for CFMO reveals that Mn ions occupying the Fe and Co position at the octahedral site in the inverse cubic spinel phase. The structure and magnetism in CFMO are further corroborated by bond length and bond angle calculations. The dielectric constant dispersion of CFMO in the frequency range of 20?Hz–1?MHz fits to the modified Debye's function with more than one ion contributing to the relaxation. The relaxation time and spread factor derived from modeling the experimental data are ?10{sup ?4}?s and ?0.35(±0.05), respectively.

Ramana, C. V., E-mail: rvchintalapalle@utep.edu; Kolekar, Y. D.; Kamala Bharathi, K. [Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States); Sinha, B. [Functional Nanopowder Material Division, Korea Institute of Material Science, Changwon 642-831, Gyeongnam (Korea, Republic of); Ghosh, K. [Department of Physics, Astronomy and Materials Science, Missouri State University, Springfield, Missouri 65897 (United States)

2013-11-14

43

Iron-based soft magnetic composites with MnZn ferrite nanoparticles coating obtained by solgel method  

E-print Network

Iron-based soft magnetic composites with Mn­Zn ferrite nanoparticles coating obtained by sol focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn­Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm

Volinsky, Alex A.

44

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. 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

45

Magnetic properties of Co-ferrite-doped hydroxyapatite nanoparticles having a core\\/shell structure  

Microsoft Academic Search

The magnetic properties of Co-ferrite-doped hydroxyapatite (HAP) nanoparticles of composition Ca10?3xFe2xCox(PO4)6(OH)2 (where x=0, 0.1, 0.2, 0.3, 0.4 and 0.5% mole) are studied. Transmission electron microscope micrograms show that the 90nm size nanoparticles annealed at 1250°C have a core\\/shell structure. Their electron diffraction patterns show that the shell is composed of the hydroxyapatite and the core is composed of the Co-ferrite,

N. Petchsang; W. Pon-On; J. H. Hodak; I. M. Tang

2009-01-01

46

Effect of cobalt substitution on structural and magnetic properties and chromium adsorption of manganese ferrite nano particles  

NASA Astrophysics Data System (ADS)

Manganese ferrite (MnFe2O4) and cobalt doped manganese ferrite (Mn1-xCoxFe2O4) with x=0, 0.2, 0.4, 0.6, and 0.8 are synthesized at pH 11 and an annealing temperature of 900 °C, through co-precipitation technique. The particle sizes are found to be in the range of 30-35 nm. The varying dopant concentrations influence the crystalline edges, surface morphology and magnetic properties of the samples. Particle size initially increases for the incorporation of cobalt up to x=0.6 and then decreases. As cobalt concentration increases, the saturation magnetization increases up to x=0.6 and then decreases. Stretching and bending of bonds at tetrahedral and octahedral sites respectively are noticed and they shift towards the longer wavelengths. The samples are tested for their application as adsorbents of toxic heavy metal Cr(VI). The adsorption efficiency variations with dopant concentrations of samples, quantity of adsorbent and concentrations of chromium are studied.

Ahalya, K.; Suriyanarayanan, N.; Ranjithkumar, V.

2014-12-01

47

Chemical equilibria involved in the oxygen-releasing step of manganese ferrite water-splitting thermochemical cycle  

NASA Astrophysics Data System (ADS)

Sodium ferrimanganite carbonatation reaction was investigated at different temperatures/carbon dioxide partial pressures to evaluate the feasibility of the thermochemical water-splitting cycle based on the MnFe 2O 4/Na 2CO 3/Na(Mn 1/3Fe 2/3)O 2 system. After thermal treatments in selected experimental conditions, the obtained powder samples were investigated by using the X-ray diffraction (XRD) technique and Rietveld analysis. Two different lamellar Na 1-xMn 1/3Fe 2/3O 2-? phases were observed together with the expected MnFe 2O 4/Na 2CO 3 mixture. Different equilibrium regions among sodium-depleted lamellar phases, manganese ferrite and sodium carbonate were found as a function of the different reaction conditions. A hypothesis concerning the regeneration mechanism of the initial compounds is proposed. Chemical equilibrium between stoichiometric and sub-stoichiometric forms of sodium ferrimanganite and sodium carbonate formation/dissociation appears to be essential factors governing the oxygen-releasing step of the manganese ferrite thermochemical cycle.

Seralessandri, L.; Bellusci, M.; Alvani, C.; La Barbera, A.; Padella, F.; Varsano, F.

2008-08-01

48

Copper ferrite nanoparticle-mediated N-arylation of heterocycles: a ligand-free reaction  

Microsoft Academic Search

The synergistic effects of iron and copper in copper ferrite nanoparticles for the N-arylation of heterocycles with aryl halides were demonstrated. The magnetic nature of the catalyst facilitates its removal from the reaction medium for further use. Negligible leaching of Cu and Fe in consecutive cycles makes the catalyst economical and environmentally benign for C–N cross-coupling reactions.

Niranjan Panda; Ashis Kumar Jena; Sasmita Mohapatra; Smruti Ranjan Rout

2011-01-01

49

Assessment of cytotoxicity and oxidative effect of Bismuth Ferrite (BFO) harmonic nanoparticles for localized DNA photo-interaction  

NASA Astrophysics Data System (ADS)

Bismuth Ferrite nanoparticles have been recently used to selectively interact with malignant cell DNA via in situ generated second harmonic in a novel theranostics protocol [Nanoscale 6(5), pp. 2929, 2014]. In this report, we extend the screening of biocompatibility of BFO uncoated uncoated nanoparticles and assess the nanoparticle- mediated production of reactive oxygen species as a function of excitation wavelength.

Staedler, Davide; Magouroux, Thibaud; Passemard, Solène; Ciepielewski, Daniel; Gerber-Lemaire, Sandrine; Wolf, Jean-Pierre; Bonacina, Luigi

2014-09-01

50

Processing of manganese zinc ferrites for high-frequency switch-mode power supplies  

Microsoft Academic Search

The development and the continued success of switch-mode power supplies have created an expanding commercial market. This market is continually challenging the ferrite industry to produce high-quality ferrite cores capable of operating at increasingly higher frequencies. The advantage of the switch-mode power supply is that, as the switching frequency is increased, power output also increases. This allows smaller core volumes

C. R. Hendricks; V. W. R. Amarakoon; D. Sullivan

1991-01-01

51

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

52

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

53

Effect of fuel ratio and the impact of annealing temperature on particle size, magnetic and dielectric properties of manganese substituted CuFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese substituted copper ferrite nanoparticles were prepared by an auto-combustion technique. The preparation of nanoparticles was carried out using different fuel ratio such as 50%, 75% and 100% under combustion process. The products were characterized by XRD, SEM, EDX, TEM and VSM techniques. The reaction process has a significant role in controlling particle size which is identified from this study. The size of the particles in the range of ?9-45 nm is obtained only at the 50% fuel ratio. The effect of fuel combustion ratio on the magnetic properties is discussed with the help of variation in saturation magnetization (Ms) and coercivity (Hc) by vibrating sample magnetometer (VSM). The saturation magnetization is decreased with increasing the fuel ratio. The dielectric loss and low value of dielectric constant have been measured in the frequency range of 100 kHz-5 MHz.

Ranjith Kumar, E.; Jayaprakash, R.; Chandrasekaran, J.

2013-12-01

54

Hyperthermia HeLa cell treatment with silica coated manganese oxide nanoparticles  

E-print Network

HeLa tumour cells incubated with ferromagnetic nanoparticles of manganese oxide perovskite La0.56(SrCa)0.22MnO3 were treated with a high frequency alternating magnetic field. The particles were previously coated with silica to improve their biocompatibility. The control assays made with HeLa tumour cells showed that cell survival and growth rate were not affected by the particle internalization in cells, or by the electromagnetic field on cells without nanoparticles. The application of an alternating electromagnetic field to cells incubated with this silica coated manganese oxide induced a significant cellular damage that finally lead to cell death by an apoptotic mechanism.

Villanueva, A; Alonso, JM; Rueda, T; Martínez, A; Crespo, P; Morales, MP; Fernandez, MA Gonzalez; Valdes, J; Rivero, G

2009-01-01

55

Preparation of Soft Manganese Ferrite and Inventional of its Magnetic Properties and Mn55 Nuclear Magnetic Resonance  

NASA Astrophysics Data System (ADS)

In this study, Mn-ferrite has been prepared with nominal formula of MnFe2O4, using the dry conventional ceramic method. The raw materials were Mobarakeh steel company modified domestic iron oxide and Merk manganese oxide. XRD patterns of the prepared samples show that they are single phase. Magnetic measurements have been performed on the toroidal samples sintered in different temperatures, using a hystograph unit MPG100D model. The results of measurements show that optimum formation pressures to obtain maximum relative magnetic permeability and hystersis. We report here the observation of the Mn55 nuclear magnetic resonance associated with the Mn2 + ion in the ferromagnetic spinel MnFe2O4 also.

Soleimani, R.; Soleimani, M.; Gheisari Godarzi, M.; Askari, A.

2011-08-01

56

Preparation of magnetic spinel ferrite core\\/shell nanoparticles: Soft ferrites on hard ferrites and vice versa  

Microsoft Academic Search

Hard\\/soft CoFe2O4\\/ZnFe2O4 and soft\\/hard ZnFe2O4\\/CoFe2O4 core\\/shell nanoparticles were prepared by combining high-temperature thermolysis of metal oxide precursors with seed-mediated growth. Magnetic properties of the core\\/shell nanoparticles were compared to those of individual CoFe2O4 and ZnFe2O4 nanoparticles of similar size prepared by the same method. The structure of the core\\/shell materials was established using a combination of X-ray and neutron powder

Ombretta Masala; Darin Hoffman; Nalini Sundaram; Katharine Page; Thomas Proffen; Gavin Lawes; Ram Seshadri

2006-01-01

57

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

58

Magnetic properties of bio-synthesized zinc ferrite nanoparticles  

SciTech Connect

The magnetic properties of zinc ferrite (Zn-substituted magnetite, Zn{sub y}Fe{sub 1-y}Fe{sub 2}O{sub 4}) formed by a microbial process compared favorably with chemically synthesized materials. A metal reducing bacterium, Thermoanaerobacter, strain TOR-39 was incubated with Zn{sub x}Fe{sub 1-x}OOH (x=0.01, 0.1, and 0.15) precursors and produced nanoparticulate zinc ferrites. Composition and crystalline structure of the resulting zinc ferrites were verified using X-ray fluorescence, X-ray diffraction, transmission electron microscopy, and neutron diffraction. The average composition from triplicates gave a value for y of 0.02, 0.23, and 0.30 with the greatest standard deviation of 0.02. Average crystallite sizes were determined to be 67, 49, and 25 nm, respectively. While crystallite size decreased with more Zn substitution, the lattice parameter and the unit cell volume showed a gradual increase in agreement with previous literature values. The magnetic properties were characterized using a superconducting quantum interference device magnetometer and were compared with values for the saturation magnetization (M{sub s}) reported in the literature. The averaged M{sub s} values for the triplicates with the largest amount of zinc (y=0.30) gave values of 100.1, 96.5, and 69.7 emu/g at temperatures of 5, 80, and 300 K, respectively indicating increased magnetic properties of the bacterially synthesized zinc ferrites.

Yeary, Lucas W [ORNL; Moon, Ji Won [ORNL; Rawn, Claudia J [ORNL; Love, Lonnie J [ORNL; Rondinone, Adam Justin [ORNL; Thompson, James R [ORNL; Chakoumakos, Bryan C [ORNL; Phelps, Tommy Joe [ORNL

2011-01-01

59

Oleate Coated Magnetic Cores Based on Magnetite, Zn Ferrite and Co Ferrite Nanoparticles - Preparation, Physical Characterization and Biological Impact on Helianthus Annuus Photosynthesis  

SciTech Connect

Sodium oleate was used as coating shell for magnetite, Zn ferrite and Co ferrite powders to stabilize them in the form of aqueous magnetic suspensions. The physical characterization was carried out by applying X-ray diffraction and magnetization measurements. Both crystallite size and magnetic core diameter ranged between 7 and 11 nm. The influence of magnetic nanoparticle suspensions (corresponding to magnetic nanoparticle levels of 10{sup -14}-10{sup -15}/cm{sup 3}) on sunflower seedlings was studied considering the changes in the photosynthesis pigment levels. Similar responses were obtained for magnetite and cobalt ferrite nanoparticle treatment consisting in the apparent inhibition of chlorophyll biosynthesis while for zinc ferrite nanoparticles some concentrations seemed to have stimulatory effects on the chlorophylls as well as on the carotene levels. But the chlorophyll ratio was diminished in the case of all three types of magnetic nanoparticles meaning their slight negative effect on the light harvesting complex II (LHC II) from the chloroplast membranes and consequently on the photosynthesis efficiency.

Ursache-Oprisan, Manuela; Foca-nici, Ecaterina; Cirlescu, Aurelian; Caltun, Ovidiu; Creanga, Dorina [Al. I. Cuza' University, Faculty of Physics, 11A Blvd.Copou, 700506, Iasi (Romania)

2010-12-02

60

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

61

Nanostructural evolution from nanosheets to one-dimensional nanoparticles for manganese oxide  

SciTech Connect

Highlights: ? Nanosheets were transformed to other one-dimensional nanoparticles. ? Nanofibers, nanotubes, nanoribbons, and nanobelts were obtained. ? Nanoparticle morphology can be controlled with organic amines. ? Organic amines act as morphology directing agent. -- Abstract: This paper introduces a novel hydrothermal soft chemical synthesis process for manganese oxide nanostructured particles using two-dimensional manganese oxide nanosheets as precursor. In this process, a birnessite-type manganese oxide with a layered structure was exfoliated into its elementary layer nanosheets, and then the nanosheets were hydrothermally treated to transform the two-dimensional morphology of the nanosheets to one-dimensional nanoparticles. The manganese oxide nanofibers, nanotubes, nanobelts, nanoribbons, and fabric-ribbon-like particles constructed from nanofibers or nanobelts were obtained using this hydrothermal soft chemical process. The nanostructural evolution from the two-dimensional nanosheets to the one-dimensional nanoparticles was characterized by XRD, SEM, TEM, and TG-DTA analysis. The morphology and nanostructure of the products are strongly dependent on the molecular dimension of organic amine cations added in the reaction system. The organic amine cations act as a morphology directing agent in the nanostructural evolution process.

Pan, Hongmei [Department of Preparatory Education, Guangxi University for Nationalities, Daxuexi-Road 188, Nanning, Guangxi 530006 (China)] [Department of Preparatory Education, Guangxi University for Nationalities, Daxuexi-Road 188, Nanning, Guangxi 530006 (China); Kong, Xingang [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu-shi 761-0396 (Japan)] [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu-shi 761-0396 (Japan); Wen, Puhong [Department of Chemistry and Chemical Engineering, Baoji University of Arts and Science, 1 Gaoxin Road, Baoji, Shaanxi 721013 (China)] [Department of Chemistry and Chemical Engineering, Baoji University of Arts and Science, 1 Gaoxin Road, Baoji, Shaanxi 721013 (China); Kitayama, Tomonori [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu-shi 761-0396 (Japan)] [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu-shi 761-0396 (Japan); Feng, Qi, E-mail: feng@eng.kagawa-u.ac.jp [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu-shi 761-0396 (Japan)] [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu-shi 761-0396 (Japan)

2012-09-15

62

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

63

The anti-microbial activity of titania-nickel ferrite composite nanoparticles  

Microsoft Academic Search

A novel approach to synthesize a new generation of composite nanoparticles consisting of a photocatalytic shell of anatase-titania\\u000a and a magnetic core of nickel ferrite has been adopted combining reverse micelle and chemical hydrolysis techniques. Titania\\u000a is an effective anti-microbial agent that can be directly sprayed on infected areas of the human body or environment. Unfortunately,\\u000a titania is an electrical

S. Rana; R. D. K. Misra

2005-01-01

64

Magnetic properties of Co-ferrite-doped hydroxyapatite nanoparticles having a core\\/shell structure  

Microsoft Academic Search

The magnetic properties of Co-ferrite-doped hydroxyapatite (HAP) nanoparticles of composition Ca10-3xFe2xCox(PO4)6(OH)2 (where x=0, 0.1, 0.2, 0.3, 0.4 and 0.5% mole) are studied. Transmission electron microscope micrograms show that the 90 nm size nanoparticles annealed at 1250 °C have a core\\/shell structure. Their electron diffraction patterns show that the shell is composed of the hydroxyapatite and the core is composed of

N. Petchsang; W. Pon-On; J. H. Hodak; I. M. Tang

2009-01-01

65

Spinel lithium manganese oxide nanoparticles: unique molten salt synthesis strategy and excellent electrochemical performances.  

PubMed

As a promising candidate cathode material, spinel lithium manganese oxide nanoparticles were successfully synthesized through a novel molten salt synthesis route at relatively low temperature, using manganese dioxide nanowires as precursor. A variety of techniques were applied to characterize the spinel nanomaterial, including X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy. The average particle size of the resulting spinel nanoparticles was about 80 nm with narrow distribution. As cathode material for rechargeable lithium ion battery, the electrochemical properties were investigated. All the results show that the electrochemical performances of the homogeneous spinel nanoparticles were improved, which might be ascribed to large specific surface area, fairly narrow size distribution, and the unique synthesis strategy. PMID:19908558

Wang, Xiong; Zhu, Juanjuan; Liu, Yingjie

2009-11-01

66

Preparation of cobalt ferrite nanoparticles via a novel solvothermal approach using divalent iron salt as precursors  

SciTech Connect

Graphical abstract: CoFe{sub 2}O{sub 4} nanoparticles are obtained via solvothermal approach using Fe{sup 2+} salt as iron resource. The magnetic properties can be modified by some additives. Display Omitted Highlights: ? CoFe{sub 2}O{sub 4} nanoparticles are synthesized by a facile one-step novel solvothermal method. ? The system is firstly performed in water–glycol mixture solvent with an ordinary air surrounding. ? The ferrous ions are used as iron source without adding oxidant. ? It is firstly found the low-coercivity CoFe{sub 2}O{sub 4} nanoparticles can be obtained with the help of some additives in the synthesis system. -- Abstract: Cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles are synthesized by a facile novel solvothermal method. The reactions are firstly performed in water–glycol system and Fe{sup 2+} salt is used as iron source without oxidant help. Some factors influenced the reactions, including temperature, reaction time, additives, are investigated. The samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), respectively. The magnetic properties of some samples are detected by vibrating sample magnetometry techniques (VSM). It is firstly found that the magnetism of cobalt ferrites nanomaterials can be modified by some additives. The coercivity of CoFe{sub 2}O{sub 4} nanoparticles evidently decreases from 600 to 50 Oe in the presence of PEG-4000 in the system.

Ma, Jie, E-mail: majie0203ch@hotmail.com [College of Science, University of Shanghai for Science and Technology (China) [College of Science, University of Shanghai for Science and Technology (China); Green Bio- and Eco-Chem. Eng. Lab, University of Shanghai for Science and Technology (China); Zhao, Jiantao; Li, Wenlie [College of Science, University of Shanghai for Science and Technology (China)] [College of Science, University of Shanghai for Science and Technology (China); Zhang, Shuping [College of Science, University of Shanghai for Science and Technology (China) [College of Science, University of Shanghai for Science and Technology (China); Green Bio- and Eco-Chem. Eng. Lab, University of Shanghai for Science and Technology (China); Tian, Zhenran; Basov, Sergey [College of Science, University of Shanghai for Science and Technology (China)] [College of Science, University of Shanghai for Science and Technology (China)

2013-02-15

67

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

68

Morphology of cobalt ferrite nanoparticle-polyelectrolyte multilayered nanocomposites  

NASA Astrophysics Data System (ADS)

Novel magnetic nanocomposite films with controlled morphology were produced via the electrostatic layer-by-layer assembly of cationic CoFe 2O 4 nanoparticles and anionic poly(3,4-ethylenedioxy thiophene)/poly(styrene sulfonic acid) (PEDOT:PSS) complex. The electrostatic interaction between nanoparticle and the polyelectrolyte complex ensured a stepwise growth of the nanocomposite film with virtually identical amounts of materials being adsorbed at each deposition cycle as observed by UV-vis spectroscopy. AFM images acquired under the tapping mode revealed a globular morphology with dense and continuous layers of nanoparticles with voids being filled with polymeric material.

Alcantara, G. B.; Paterno, L. G.; Fonseca, F. J.; Morais, P. C.; Soler, M. A. G.

2011-05-01

69

Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications.  

PubMed

Magnetic hyperthermia uses AC stimulation of magnetic nanoparticles to generate heat for cancer cell destruction. Whilst nanoparticles produced inside magnetotactic bacteria have shown amongst the highest reported heating to date, these particles are magnetically blocked so that strong heating occurs only for mobile particles, unless magnetic field parameters are far outside clinical limits. Here, nanoparticles extracellularly produced by the bacteria Geobacter sulfurreducens are investigated that contain Co or Zn dopants to tune the magnetic anisotropy, saturation magnetization and nanoparticle sizes, enabling heating within clinical field constraints. The heating mechanisms specific to either Co or Zn doping are determined from frequency dependent specific absorption rate (SAR) measurements and innovative AC susceptometry simulations that use a realistic model concerning clusters of polydisperse nanoparticles in suspension. Whilst both particle types undergo magnetization relaxation and show heating effects in water under low AC frequency and field, only Zn doped particles maintain relaxation combined with hysteresis losses even when immobilized. This magnetic heating process could prove important in the biological environment where nanoparticle mobility may not be possible. Obtained SARs are discussed regarding clinical conditions which, together with their enhanced MRI contrast, indicate that biogenic Zn doped particles are promising for combined diagnostics and cancer therapy. PMID:25232657

Céspedes, Eva; Byrne, James M; Farrow, Neil; Moise, Sandhya; Coker, Victoria S; Bencsik, Martin; Lloyd, Jonathan R; Telling, Neil D

2014-10-01

70

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

71

Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications  

NASA Astrophysics Data System (ADS)

Magnetic hyperthermia uses AC stimulation of magnetic nanoparticles to generate heat for cancer cell destruction. Whilst nanoparticles produced inside magnetotactic bacteria have shown amongst the highest reported heating to date, these particles are magnetically blocked so that strong heating occurs only for mobile particles, unless magnetic field parameters are far outside clinical limits. Here, nanoparticles extracellularly produced by the bacteria Geobacter sulfurreducens are investigated that contain Co or Zn dopants to tune the magnetic anisotropy, saturation magnetization and nanoparticle sizes, enabling heating within clinical field constraints. The heating mechanisms specific to either Co or Zn doping are determined from frequency dependent specific absorption rate (SAR) measurements and innovative AC susceptometry simulations that use a realistic model concerning clusters of polydisperse nanoparticles in suspension. Whilst both particle types undergo magnetization relaxation and show heating effects in water under low AC frequency and field, only Zn doped particles maintain relaxation combined with hysteresis losses even when immobilized. This magnetic heating process could prove important in the biological environment where nanoparticle mobility may not be possible. Obtained SARs are discussed regarding clinical conditions which, together with their enhanced MRI contrast, indicate that biogenic Zn doped particles are promising for combined diagnostics and cancer therapy.Magnetic hyperthermia uses AC stimulation of magnetic nanoparticles to generate heat for cancer cell destruction. Whilst nanoparticles produced inside magnetotactic bacteria have shown amongst the highest reported heating to date, these particles are magnetically blocked so that strong heating occurs only for mobile particles, unless magnetic field parameters are far outside clinical limits. Here, nanoparticles extracellularly produced by the bacteria Geobacter sulfurreducens are investigated that contain Co or Zn dopants to tune the magnetic anisotropy, saturation magnetization and nanoparticle sizes, enabling heating within clinical field constraints. The heating mechanisms specific to either Co or Zn doping are determined from frequency dependent specific absorption rate (SAR) measurements and innovative AC susceptometry simulations that use a realistic model concerning clusters of polydisperse nanoparticles in suspension. Whilst both particle types undergo magnetization relaxation and show heating effects in water under low AC frequency and field, only Zn doped particles maintain relaxation combined with hysteresis losses even when immobilized. This magnetic heating process could prove important in the biological environment where nanoparticle mobility may not be possible. Obtained SARs are discussed regarding clinical conditions which, together with their enhanced MRI contrast, indicate that biogenic Zn doped particles are promising for combined diagnostics and cancer therapy. Electronic supplementary information (ESI) available: Further details of the cluster model of polydisperse nanoparticles used for the AC susceptibility simulations (Fig. S1 to S3). Examples of the heating curves and the linear fit used to determine the SAR values are shown in Fig. S4. Fig. S5 exhibits the energy loss per mass of iron during magnetic hyperthermia (from SAR values) normalized to H2 and frequency for further comparison among samples. Fig. S6 shows the comparison between the simulations of AC susceptibility spectra including regions below and above the experimental frequency range for MNA, Zn0.2 and Zn0.4 nanoparticles suspended in solvents with different viscosities (water, glycerol and a hypothetical high viscous solvent). Fig. S7 exhibits a comparison among the simulated ?'' susceptibility of MNA, Zn0.2 and Zn0.4 nanoparticles (a) in water and (b) in glycerol. See DOI: 10.1039/c4nr03004d

Céspedes, Eva; Byrne, James M.; Farrow, Neil; Moise, Sandhya; Coker, Victoria S.; Bencsik, Martin; Lloyd, Jonathan R.; Telling, Neil D.

2014-10-01

72

In-field Mossbauer study of disordered surface spins in core/shell ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetization and Mossbauer spectroscopy measurements are performed at low temperature under high field, on nanoparticles with a nickel ferrite core and a maghemite shell. These nanoparticles present finite size and surface effects, together with exchange anisotropy. High field magnetization brings the evidences of a monodomain ordered core and surface spins freezing in disorder at low temperature. Mossbauer spectra at 4.2 K present an extra contribution from the disordered surface which is field dependent. Field and size dependences of this latter show a progressive spin alignment along the ferrite core which is size dependent. The weak surface pinning condition of the nanoparticles confirms that the spin disorder is localized in the external shell. The underfield decrease in the mean canting angle in the superficial shell is then directly related to the unidirectional exchange anisotropy through the interface between the ordered core and the disordered shell. The obtained anisotropy field HEa scales as the inverse of the nanoparticle diameter, validating its interfacial origin. The associated anisotropy constant KEa equals 2.5×10-4 J/m2.

Sousa, E. C.; Rechenberg, H. R.; Depeyrot, J.; Gomes, J. A.; Aquino, R.; Tourinho, F. A.; Dupuis, V.; Perzynski, R.

2009-11-01

73

Structural, magnetic, dielectric and optical properties of nickel ferrite nanoparticles synthesized by co-precipitation method  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles were synthesized by wet chemical co-precipitation method and the corresponding temperature dependent structural, magnetic and optical properties of these nanoparticles have been investigated. X-ray diffraction patterns show the single phase cubic spinal crystal structure belonging to the space group Fd3m. The average crystallite size varies in the range 8-20 nm with varying sintering temperature. Raman spectroscopy exhibits a doublet-like peak behaviour which indicates the presence of mixed spinel structure. The saturation magnetization, coercivity and remanence increase with increasing sintering temperature from 250 to 550 °C. The non-saturation and low values of magnetization at high fields indicate the strong surface effects to magnetization in NiFe2O4 nanoparticles. The g-value calculated from electron spin resonance spectrum indicates the transfer of divalent metallic ion from octahedral to tetrahedral site (i.e. mixed spinel structure). The dielectric permittivity, loss tangent and ac conductivity measurements show strong temperature dependence at all frequencies. The observed ac conductivity response suggests that the conduction in ferrite nanoparticles is due to feeble polaron hopping between Fe3+/Fe2+ ions. Room temperature UV-vis diffuse spectra indicate that NiFe2O4 is an indirect band gap material with band gap ranges from 1.27 to 1.47 eV with varying sintering temperature. The photoluminescence study clearly indicates that the Ni2+ ions occupy both octahedral and tetrahedral sites confirming mixed spinel structure.

Joshi, Seema; Kumar, Manoj; Chhoker, Sandeep; Srivastava, Geetika; Jewariya, Mukesh; Singh, V. N.

2014-11-01

74

Manganese  

MedlinePLUS

... no RDAs for a nutrient, the Adequate Intake (AI) is used as a guide. The AI is the estimated amount of the nutrient that ... assumed to be adequate. The daily Adequate Intake (AI) levels for manganese are: infants birth to 6 ...

75

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

Microsoft Academic Search

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

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

2012-01-01

76

Manganese-enhanced MRI of rat brain based on slow cerebral delivery of manganese(II) with silica-encapsulated Mn x Fe(1-x) O nanoparticles.  

PubMed

In this work, we report a monodisperse bifunctional nanoparticle system, MIO@SiO2 -RITC, as an MRI contrast agent [core, manganese iron oxide (MIO); shell, amorphous silica conjugated with rhodamine B isothiocyanate (RITC)]. It was prepared by thermal decomposition and modified microemulsion methods. The nanoparticles with varying iron to manganese ratios displayed different saturated magnetizations and relaxivities. In vivo MRI of rats injected intravenously with MIO@SiO2-RITC nanoparticles exhibited enhancement of the T1 contrast in brain tissue, in particular a time-delayed enhancement in the hippocampus, pituitary gland, striatum and cerebellum. This is attributable to the gradual degradation of MIO@SiO2-RITC nanoparticles in the liver, resulting in the slow release of manganese(II) [Mn(II)] into the blood pool and, subsequently, accumulation in the brain tissue. Thus, T1-weighted contrast enhancement was clearly detected in the anatomic structure of the brain as time progressed. In addition, T2*-weighted images of the liver showed a gradual darkening effect. Here, we demonstrate the concept of the slow release of Mn(II) for neuroimaging. This new nanoparticle-based manganese contrast agent allows one simple intravenous injection (rather than multiple infusions) of Mn(II) precursor, and results in delineation of the detailed anatomic neuroarchitecture in MRI; hence, this provides the advantage of the long-term study of neural function. PMID:23526743

Chen, Wei; Lu, Fang; Chen, Chiao-Chi V; Mo, Kuan-Chi; Hung, Yann; Guo, Zhi-Xuan; Lin, Chia-Hui; Lin, Ming-Huang; Lin, Yu-Hsuan; Chang, Chen; Mou, Chung-Yuan

2013-09-01

77

Mesoporous Silica Nanoparticle-Stabilized and Manganese-Modified Rhodium Nanoparticles as Catalysts for Highly Selective Synthesis of Ethanol and Acetaldehyde from Syngas  

SciTech Connect

Well-defined and monodispersed rhodium nanoparticles as small as approximately 2?nm were encapsulated in?situ and stabilized in a mesoporous silica nanoparticle (MSN) framework during the synthesis of the mesoporous material. Although both the activity and selectivity of MSN-encapsulated rhodium nanoparticles in CO hydrogenation could be improved by the addition of manganese oxide as expected, the carbon selectivity for C2 oxygenates (including ethanol and acetaldehyde) was unprecedentedly high at 74.5?% with a very small amount of methanol produced if rhodium nanoparticles were modified by manganese oxide with very close interaction.

Huang, Yulin; Deng, Weihua; Guo, Enruo; Chung, Po-Wen; Chen, Senniang; Trewyn, Brian; Brown, Robert; Lin, Victor

2012-03-30

78

Silica encapsulated manganese perovskite nanoparticles for magnetically induced hyperthermia without the risk of overheating  

Microsoft Academic Search

Nanoparticles of manganese perovskite of the composition La0.75Sr0.25MnO3 uniformly coated with silica were prepared by encapsulation of the magnetic cores (mean crystallite size 24 nm) using tetraethoxysilane followed by fractionation. The resulting hybrid particles form a stable suspension in an aqueous environment at physiological pH and possess a narrow hydrodynamic size distribution. Both calorimetric heating experiments and direct measurements of

O. Kaman; E. Pollert; P. Veverka; M. Veverka; E. Hadová; K. Knízek; M. Marysko; P. Kaspar; M. Klementová; V. Grünwaldová; S. Vasseur; R. Epherre; S. Mornet; G. Goglio; E. Duguet

2009-01-01

79

Non-platinum electrocatalysts: Manganese oxide nanoparticle-cobaltporphyrin binary catalysts for oxygen reduction  

Microsoft Academic Search

This study is concerned with the development of non-platinum electrocatalysts for the efficient 4-electron reduction of molecular\\u000a oxygen to water in acidic media. A binary catalyst composed of electrodeposited manganese oxide nanoparticles (nano-MnO\\u000a x\\u000a ) and cobalt porphyrin macro complex (CoP) has been proposed in. The modification of glassy carbon (GC) electrode with CoP\\u000a alone resulted in a significant positive

Mohamed S. El-Deab; Sameh H. Othman; Takeyoshi Okajima; Takeo Ohsaka

2008-01-01

80

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

81

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

82

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 (M(R)/M(S) ~ 1), suggesting cubic anisotropy in the system, whereas for the NP sample, typical features of uniaxial anisotropy (M(R)/M(S) ~ 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 (K(E)) of the system. A high-temperature enhancement of H(C) and K(E) 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

83

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 (50-70nm) have been synthesized via emulsion polymerization. The complex permittivity, permeability, and microwave absorption properties of the composite were studied in the 12.4-18GHz (Ku band) frequency range. The composite has shown high shielding effectiveness due to absorption (SEA) of 28.9dB (˜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

84

Microwave characterization of magnetically hard and soft ferrite nanoparticles in K-band  

NASA Astrophysics Data System (ADS)

Nano-sized magnetic particles show great promise in improving the performance of microwave absorbers with respect to the corresponding bulk materials. In this paper, magnetically hard and soft ferrite nanoparticles (CoFe2O4 and Fe3O4) having an average size of 14 and 11 nm were prepared by co-precipitation method and characterized in terms of morphology, structure, and magnetic properties. Their permeability and permittivity were measured by a waveguide technique, embedding each sample in a host medium. Their parameters at microwave frequencies were retrieved by comparing different effective medium equations.

Della Pina, C.; Falletta, E.; Ferretti, A. M.; Ponti, A.; Gentili, G. G.; Verri, V.; Nesti, R.

2014-10-01

85

Structural and morphological studies of manganese substituted CoFe2O4 and NiFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

Nanocrystalline manganese substituted cobalt and nickel ferrites have been synthesized through the evaporation method by using egg white. These powders were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The XRD pattern of manganese substituted spinel ferrites contains some impurity peaks, which are the decomposition of the ferrites to ?-Fe2O3 phase at higher annealing temperature. The microstructure and particle size of the annealed sample analyzed by TEM, which gives the particle size well with XRD. The magnetic properties were measured using Vibrating Sample Magnetometer (VSM). The surface/near-surface chemical states of the nanocrystalline manganese substituted cobalt and nickel ferrites are analyzed by XPS within a range of binding energies of 0-1000 eV.

Ranjith kumar, E.; Jayaprakash, R.; Patel, Rajesh

2013-10-01

86

Valence-driven electrical behavior of manganese-modified bismuth ferrite thin films  

NASA Astrophysics Data System (ADS)

BiFe0.95R0.05O3 (Mn2+, Mn3+, and Mn4+) thin films with (110) orientation were fabricated on SrRuO3/Pt/TiO2/SiO2/Si(100) substrates via rf sputtering. With the increasing valence of Mn in BiFe0.95R0.05O3, the concentration of Fe2+ increases, whereas the concentration of oxygen vacancies decreases. The electrical properties of BiFe0.95R0.05O3 are correlated with the valence of Mn. Their leakage current density is dependent on the concentration of oxygen vacancies caused by different valences of Mn. Their P-E loops become better with the increasing valence of Mn owing to a lower leakage current density in high electric field regions, and a large remanent polarization of 2Pr ˜ 145.2 ?C/cm2 is obtained for the Mn4+-doped film. For the Mn2+-doped bismuth ferrite film, the space-charge-limited conduction and Schottky barrier dominate its leakage behavior under a negative electric field, the Ohmic conduction and Schottky barrier are involved in the leakage behavior under a positive electric field, and the interface-limited Fowler-Nordheim tunneling is their dominant mechanism in a high electric field region. In contrast, an Ohmic conduction dominates the leakage behavior of Mn3+- and Mn4+-doped films regardless of negative and positive directions or measurement temperatures.

Wu, Jiagang; Wang, John; Xiao, Dingquan; Zhu, Jianguo

2011-06-01

87

Synchrotron study on load partitioning between ferrite/martensite and nanoparticles of a 9Cr ODS steel  

NASA Astrophysics Data System (ADS)

Oxide dispersion strengthened (ODS) steels exhibit exceptional radiation resistance and high-temperature creep strength when compared to traditional ferritic and ferritic/martensitic (F/M) steels. Their excellent mechanical properties result from very fine nanoparticles dispersed within the matrix. In this work, we applied a high-energy synchrotron radiation X-ray to study the deformation process of a 9Cr ODS steel. The load partitioning between the ferrite/martensite and the nanoparticles was observed during sample yielding. During plastic deformation, the nanoparticles experienced a dramatic loading process, and the internal stress on the nanoparticles increased to a maximum value of 3.7 GPa, which was much higher than the maximum applied stress (?986 MPa). After necking, the loading capacity of the nanoparticles was significantly decreased due to a debonding of the particles from the matrix, as indicated by a decline in lattice strain/internal stress. Due to the load partitioning, the ferrite/martensite slightly relaxed during early yielding, and slowly strained until failure. This study develops a better understanding of loading behavior for various phases in the ODS F/M steel.

Mo, Kun; Zhou, Zhangjian; Miao, Yinbin; Yun, Di; Tung, Hsiao-Ming; Zhang, Guangming; Chen, Weiying; Almer, Jonathan; Stubbins, James F.

2014-12-01

88

Antimicrobial function of Nd3+-doped anatase titania-coated nickel ferrite composite nanoparticles: a biomaterial system.  

PubMed

The present study describes and makes a relative comparison of the antimicrobial function of undoped and neodymium-doped titania coated-nickel ferrite composite nanoparticles processed by uniquely combining the reverse micelle and chemical hydrolysis approaches. This methodology facilitates the formation of undoped and doped photocatalytic titania shells and a magnetic ferrite core. The ferrite core is needed to help in the removal of particles from the sprayed surface using a small magnetic field. Doping of the titania shell with neodymium significantly enhances the photocatalytic and anti-microbial function of the core-shell composite nanoparticles without influencing the magnetic characteristics of the nickel ferrite core. The increased performance is believed to be related to the inhibition of electron-hole recombination and a decrease in the band gap energy of titania. The retention of magnetic strength ensures controlled movement of the composite nanoparticles by the magnetic field, facilitating their application as removable anti-microbial photocatalyst nanoparticles. The consistent behavior of the composite nanoparticles points to the viability of the synthesis process adopted. PMID:16765882

Rana, S; Rawat, J; Sorensson, M M; Misra, R D K

2006-07-01

89

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

90

The interaction of manganese nanoparticles with PC-12 cells induces dopamine depletion.  

PubMed

This investigation was designed to determine whether nano-sized manganese oxide (Mn-40 nm) particles would induce dopamine (DA) depletion in a cultured neuronal phenotype, PC-12 cells, similar to free ionic manganese (Mn(2+)). Cells were exposed to Mn-40 nm, Mn(2+) (acetate), or known cytotoxic silver nanoparticles (Ag-15 nm) for 24 h. Phase-contrast microscopy studies show that Mn-40 nm or Mn(2+) exposure did not greatly change morphology of PC-12 cells. However, Ag-15 nm and AgNO(3) produce cell shrinkage and irregular membrane borders compared to control cells. Further microscopic studies at higher resolution demonstrated that Mn-40 nm nanoparticles and agglomerates were effectively internalized by PC-12 cells. Mitochondrial reduction activity, a sensitive measure of particle and metal cytotoxicity, showed only moderate toxicity for Mn-40 nm compared to similar Ag-15 nm and Mn(2+) doses. Mn-40 nm and Mn(2+) dose dependently depleted DA and its metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), while Ag-15 nm only significantly reduced DA and DOPAC at concentrations of 50 mug/ml. Therefore, the DA depletion of Mn-40 nm was most similar to Mn(2+), which is known to induce concentration-dependent DA depletion. There was a significant increase (> 10-fold) in reactive oxygen species (ROS) with Mn-40 nm exposure, suggesting that increased ROS levels may participate in DA depletion. These results clearly demonstrate that nanoscale manganese can deplete DA, DOPAC, and HVA in a dose-dependent manner. Further study is required to evaluate the specific intracellular distribution of Mn-40 nm nanoparticles, metal dissolution rates in cells and cellular matrices, if DA depletion is induced in vivo, and the propensity of Mn nanoparticles to cross the blood-brain barrier or be selectively uptaken by nasal epithelium. PMID:16714391

Hussain, Saber M; Javorina, Amanda K; Schrand, Amanda M; Duhart, Helen M; Ali, Syed F; Schlager, John J

2006-08-01

91

Synthesis of nickel–zinc ferrite magnetic nanoparticle and dye degradation using photocatalytic ozonation  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Nickel–zinc ferrite magnetic nanoparticle (NZFMN) was synthesized and characterized. ? Dye degradation by photocatalytic ozonation using NZFMN was studied. ? Formate, acetate and oxalate were detected as dominant dye degradation aliphatic intermediates. ? Nitrate, sulfate and chloride ions were detected as mineralization products of dyes. ? NZFMN was an effective magnetic nanocatalyst to degrade dyes. -- Abstract: In this paper, nickel–zinc ferrite magnetic nanoparticle (NZFMN) was synthesized and its dye degradation ability using photocatalytic ozonation was investigated. The NZFMN was characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM), Fourier transforms infrared (FTIR) and alternative gradient force magnetometer (AGFM). Reactive Red 198 (RR198) and Direct Green 6 (DG6) were used as dye models. UV–vis and ion chromatography (IC) analyses were employed to study dye degradation. The effects of operational parameters on decolorization such as NZFMN dosage, dye concentration, salt and pH were studied. RR198 and DG6 were completely decolorized (100%) by photocatalytic ozonation using NZFMN. Formate, acetate and oxalate anions were detected as dominant aliphatic intermediates. Nitrate, sulfate and chloride ions were detected as mineralization products of dyes. Results showed that the photocatalytic ozonation using NZFMN was a very effective method for dye degradation.

Mahmoodi, Niyaz Mohammad, E-mail: mahmoodi@icrc.ac.ir [Department of Environmental Research, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of); Bashiri, Marziyeh; Moeen, Shirin Jebeli [Department of Environmental Research, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of)] [Department of Environmental Research, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of)

2012-12-15

92

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

93

Microstructural and Mössbauer 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. PMID:21851597

2011-01-01

94

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

95

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

96

Evaluation of nickel ferrite nanoparticles coated with oleylamine by NMR relaxation measurements and magnetic hyperthermia.  

PubMed

Nickel ferrite nanoparticles were synthesized via a facile solvothermal approach. Oleylamine (OAm) was used in all synthetic procedures as a stabilizing agent and solvent. By varying the polarity of the solvents, hydrophobic NiFe2O4 nanoparticles coated with OAm of relatively similar sizes (9-11.7 nm) and in a range of magnetization values (32.0-53.5 emu g(-1)) were obtained. The as-prepared hydrophobic nanoparticles were characterized by XRD, TEM, SEM, TGA and VSM and converted to hydrophilic by two different approaches. The addition of a positively charged ligand (cetyltrimethyl ammonium bromide, CTAB) and the ligand exchange procedure (2,3-dimercaptosuccinic acid, DMSA) have been successfully applied. The aqueous suspensions of NiFe2O4@CTAB and NiFe2O4@DMSA showed good colloidal stability after a long period of time. The different surface modification affected both the NMR relaxometric measurements and the hyperthermia effects. In both techniques CTAB modification demonstrated higher r2 relaxivity (278.9 s(-1) mM(-1) in an NMR spectrometer at 11.7 T) and SAR values (423.4 W g(-1) at an applied AC field with a particle concentration of 0.5 mg mL(-1)). The results indicate that a coating with a larger molecule as CTAB under the same size, shape and magnetization of NiFe2O4 NPs gave rise to NMR relaxometric properties and heating efficacy. PMID:24413465

Menelaou, M; Georgoula, K; Simeonidis, K; Dendrinou-Samara, C

2014-03-01

97

Photochemical modulation of biosafe manganese nanoparticles on Vigna radiata: a detailed molecular, biochemical, and biophysical study.  

PubMed

Manganese (Mn) is an essential element for plants which intervenes mainly in photosynthesis. In this study we establish that manganese nanoparticles (MnNP) work as a better micronutrient than commercially available manganese salt, MnSO4 (MS) at recommended doses on leguminous plant mung bean (Vigna radiata) under laboratory condition. At higher doses it does not impart toxicity to the plant unlike MS. MnNP-treated chloroplasts show greater photophosphorylation, oxygen evolution with respect to control and MS-treated chloroplasts as determined by biophysical and biochemical techniques. Water splitting by an oxygen evolving complex is enhanced by MnNP in isolated chloroplast as confirmed by polarographic and spectroscopic techniques. Enhanced activity of the CP43 protein of a photosystem II (PS II) Mn4Ca complex influenced better phosphorylation in the electron transport chain in the case of MnNP-treated chloroplast, which is evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and corresponding Western blot analysis. To the best of our knowledge this is the first report to augment photosynthesis using MnNP and its detailed correlation with different molecular, biochemical and biophysical parameters of photosynthetic pathways. At effective dosage, MnNP is found to be biosafe both in plant and animal model systems. Therefore MnNP would be a novel potential nanomodulator of photochemistry in the agricultural sector. PMID:24144189

Pradhan, Saheli; Patra, Prasun; Das, Sumistha; Chandra, Sourov; Mitra, Shouvik; Dey, Kushal Kumar; Akbar, Shirin; Palit, Pratip; Goswami, Arunava

2013-11-19

98

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

99

Synthesis of nickel-zinc ferrite nanoparticles in polyol: morphological, structural and magnetic studies  

NASA Astrophysics Data System (ADS)

Nickel-zinc ferrite monodisperse nanoparticles are synthesized by forced hydrolysis in diethylenglycol. FC and ZFC susceptibility curves suggest that they present superparmagnetic behaviour with a blocking temperature between 63 and 15 K depending on the zinc content. The saturation magnetization of the nanocrystals at 5 K is very close to that of bulk materials, and very high compared to that of similar particles prepared by other chemical routes. High Resolution Transmission Electron Microscopy and In-field Mössbauer studies show clearly that these relatively high values are mainly due to: (i) the high crystalline quality of the particles and (ii) a cation distribution different from the classical distribution encountered in the bulk material.

Beji, Z.; Ben Chaabane, T.; Smiri, L. S.; Ammar, S.; Fiévet, F.; Jouini, N.; Grenèche, J. M.

2006-02-01

100

Aqueous synthesis and transmission electron microscopy observation of seed-grown spherical ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Uniform-sized spherical iron ferrite nanoparticles grew on seed crystals in an aqueous solution containing sucrose. Using the seed crystals which were highly dispersed in acidic or alkaline seed-crystal suspension without relation to pH of the suspension, we widely controlled the particle diameter in the range 20-200 nm by changing the additive amount of the seed crystals. By transmission electron microscopy observation and X-ray diffraction analysis, it indicated that the particles were highly crystalline but not amorphous. Selected area diffraction patterns of the particles by using transmission electron microscope revealed that the particles were composed of one to several crystals. Thus we provided the evidence that the particles grew on clusters composed of one to several seed crystals to which those of several dozen seed crystals were disintegrated.

Tanaka, T.; Tada, M.; Nakagawa, T.; Abe, M.

2012-03-01

101

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

102

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

103

Effect of abrasive grit size on wear of manganese-zinc ferrite under three-body abrasion  

NASA Technical Reports Server (NTRS)

Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and deformed layers produced in single-crystal Mn-Zn ferrites under three-body abrasion. The abrasion mechanism of Mn-Zn ferrite changes drastically with the size of abrasive grits. With 15-micron (1000-mesh) SiC grits, abrasion of Mn-Zn ferrite is due principally to brittle fracture; while with 4- and 2-micron (4000- and 6000-mesh) SiC grits, abrasion is due to plastic deformation and fracture. Both microcracking and plastic flow produce polycrystalline states on the wear surfaces of single-crystal Mn-Zn ferrites. Coefficient of wear, total thickness of the deformed layers, and surface roughness of the wear surfaces increase markedly with an increase in abrasive grit size. The total thicknesses of the deformed layers are 3 microns for the ferrite abraded by 15-micron SiC, 0.9 microns for the ferrite abraded by 4-micron SiC, and 0.8 microns for the ferrite abraded by 1-micron SiC.

Miyoshi, Kazuhisa

1987-01-01

104

Magneto-optical waveguides made of cobalt ferrite nanoparticles embedded in silica\\/zirconia organic-inorganic matrix  

Microsoft Academic Search

This paper describes a way to develop magneto-optical waveguides via sol-gel process. They are made of cobalt ferrite nanoparticles embedded in a silica\\/zirconia matrix. Thin films are coated on glass substrate using the dip-coating technique. Annealing and UV treatment are applied to finalize sample preparation. Therefore, planar waveguides combining magneto-optical properties with a low refractive index (~1,5) are obtained. M-lines

Fadi Choueikani; François Royer; Damien Jamon; Ali Siblini; Jean Jacques Rousseau; Sophie Neveu; Jamal Charara

2009-01-01

105

Manganese doping of magnetic iron oxide nanoparticles: tailoring surface reactivity for a regenerable heavy metal sorbent.  

PubMed

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. PMID:22329500

Warner, Cynthia L; Chouyyok, Wilaiwan; Mackie, Katherine E; Neiner, Doinita; Saraf, Laxmikant V; Droubay, Timothy C; Warner, Marvin G; Addleman, R Shane

2012-02-28

106

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

107

Tuning high aqueous phase uptake in nonionic water-in-oil microemulsions for the synthesis of Mn-Zn ferrite nanoparticles: phase behavior, characterization, and nanoparticle synthesis.  

PubMed

In this work, the formation of water-in-oil (w/o) microemulsions with high aqueous phase uptake in a nonionic surfactant system is investigated as potential media for the synthesis of Mn-Zn ferrite nanoparticles. A comprehensive study based on the phase behavior of systems containing precursor salts, on one hand, and precipitating agent, on the other hand, was carried out to identify key regions on (a) pseudoternary phase diagrams at constant temperature (50 °C), and (b) pseudobinary phase diagrams at constant surfactant (S):oil(O) weight ratio (S:O) as a function of temperature. The internal structure and dynamics of microemulsions were studied systematically by conductivity and self-diffusion coefficient determinations (FT PGSE (1)H NMR). It was found that nonpercolated w/o microemulsions could be obtained by appropriate tuning of composition variables and temperature, with aqueous phase concentrations as high as 36 wt % for precursor salts and 25 wt % for precipitating agent systems. Three compositions with three different dynamic behaviors (nonpercolated and percolated w/o, as well as bicontinuous microemulsions) were selected for the synthesis of Mn-Zn ferrites, resulting in nanoparticles with different characteristics. Spinel structure and superparamagnetic behavior were obtained. This study sets firm basis for a systematic study of Mn-Zn ferrite nanoparticle synthesis via different scenarios of microemulsion dynamics, which will contribute to a better understanding on the relationship of the characteristics of the obtained materials with the properties of the reaction media. PMID:22039992

Aubery, Carolina; Solans, Conxita; Sanchez-Dominguez, Margarita

2011-12-01

108

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

109

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

110

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

111

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

112

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

113

Spin-flop transition, magnetic and microwave absorption properties of ?-Fe2O4 spinel type ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

We have prepared NiFe2O4, CoFe2O4, Ni0.6Zn0.4Fe2O4 and ZnFe2O4 spinel type ferrite nanoparticles by surfactant-assisted hydrothermal process using cetyltrimethylammonium bromide (CTAB). The spin-flop transition, magnetic, dielectric and permittivity characterizations have been investigated. The spin-flop transition occurs from antiferromagnetic state to mixed state and then ferromagnetic state for Zn doped samples. The spin-flop transition occurs in the temperature range of 50-250 K. The ionic conduction, dipolar relaxation, atomic polarization and electronic polarization are the main mechanisms that contribute to the permittivity of a dielectric material. The permittivity increases with increasing frequency. This suggests a resonance behavior, which is expected when the ferrite samples are highly conductive and skin effect become significant. These samples will provide great benefits for electromagnetic applications and electromagnetic interference shielding characteristics.

Yalç?n, Orhan; Bayrakdar, Harun; Özüm, Songül

2013-10-01

114

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

115

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

116

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

117

Synthesis and magnetic characterization of cobalt-substituted ferrite (Co xFe 3-xO 4) nanoparticles  

NASA Astrophysics Data System (ADS)

Cobalt-substituted ferrite nanoparticles were synthesized with a narrow size distribution using reverse micelles formed in the system water/AOT/isooctane. Fe:Co ratios of 3:1, 4:1, and 5:1 were used in the synthesis, obtaining cobalt-substituted ferrites (Co xFe 3-xO 4) and some indication of ?-Fe 3O 4 when 4:1 and 5:1 Fe:Co ratios were used. Inductively coupled plasma mass spectroscopy (ICP-MS) verified the presence of cobalt in all samples. Fourier transform infrared (FTIR) showed bands at ˜560 and ˜400 cm -1, characteristic of the metal-oxygen bond in ferrites. Transmission electron microscopy showed that the number median diameter of the particles was ˜3 nm with a geometric deviation of ˜0.2. X-ray diffraction (XRD) confirmed the inverse spinel structure typical of ferrites with a lattice parameter of a=8.388 Å for Co 0.61Fe 0.39O 4, which is near that of CoFe 2O 4 ( a=8.394 Å). Magnetic properties were determined using a superconducting quantum interference device (SQUID). Coercivities higher than 8 kOe were observed at 5 K, whereas at 300 K the particles showed superparamagnetic behavior. The anisotropy constant was determined based on the Debye model for a magnetic dipole in an oscillating field and an expression relating ?' and the temperature of the in-phase susceptibility peak. Anisotropy constant values in the order of ˜10 6 erg/cm 3 were determined using the Debye model, whereas anisotropy constants in the order of ˜10 7 erg/cm 3 were calculated assuming ??=1 at the temperature peak of the in-phase component of the susceptibility curve as commonly done in the literature. Our analysis demonstrates that the assumption ??=1 at the temperature peak of ?' is rigorously incorrect.

Calero-DdelC, Victoria L.; Rinaldi, Carlos

2007-07-01

118

Anhydride functionalised calcium ferrite nanoparticles: A new selective magnetic material for enrichment of lead ions from water and food samples.  

PubMed

In this research a sonochemistry route for manufacture of uniform nanocrystalline CaFe2O4 and its anhydride functionalisation were reported. The potential of raw and modified material as a magnetically separable sorbent in selective enrichment of lead ions from water and food samples is outlined. This material was characterised using FT-IR, XRD, SEM and VSM techniques. The SEM and VSM results indicated that the calcium ferrite nanoparticles are sphere-like particles possessing superparamagnetic properties with an average diameter of 40nm. Various analytical parameters, including pH, contact time, type and concentration of eluent, adsorption capacity, sample volume and interference of ions, were optimised. Following a modification by anhydride, calcium ferrite selectivity toward lead ions was raised more than twofold compared to the unmodified nanoparticles. Finally a pre-concentration procedure was applied for determination of trace Pb(II) in canned tuna fish, canned tomato paste, parsley, milk and well-water samples with satisfactory results. PMID:25306327

Pirouz, Mojgan Jafari; Beyki, Mostafa Hossein; Shemirani, Farzaneh

2015-03-01

119

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. PMID:22316055

2012-01-01

120

Tunable T1 and T2 contrast abilities of manganese-engineered iron oxide nanoparticles through size control  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate the tunable T1 and T2 contrast abilities of engineered iron oxide nanoparticles with high performance for liver contrast-enhanced magnetic resonance imaging (MRI) in mice. To enhance the diagnostic accuracy of MRI, large numbers of contrast agents with T1 or T2 contrast ability have been widely explored. The comprehensive investigation of high-performance MRI contrast agents with controllable T1 and T2 contrast abilities is of high importance in the field of molecular imaging. In this study, we synthesized uniform manganese-doped iron oxide (MnIO) nanoparticles with controllable size from 5 to 12 nm and comprehensively investigated their MRI contrast abilities. We revealed that the MRI contrast effects of MnIO nanoparticles are highly size-dependent. By controlling the size of MnIO nanoparticles, we can achieve T1-dominated, T2-dominated, and T1-T2 dual-mode MRI contrast agents with much higher contrast enhancement than the corresponding conventional iron oxide nanoparticles.In this paper, we demonstrate the tunable T1 and T2 contrast abilities of engineered iron oxide nanoparticles with high performance for liver contrast-enhanced magnetic resonance imaging (MRI) in mice. To enhance the diagnostic accuracy of MRI, large numbers of contrast agents with T1 or T2 contrast ability have been widely explored. The comprehensive investigation of high-performance MRI contrast agents with controllable T1 and T2 contrast abilities is of high importance in the field of molecular imaging. In this study, we synthesized uniform manganese-doped iron oxide (MnIO) nanoparticles with controllable size from 5 to 12 nm and comprehensively investigated their MRI contrast abilities. We revealed that the MRI contrast effects of MnIO nanoparticles are highly size-dependent. By controlling the size of MnIO nanoparticles, we can achieve T1-dominated, T2-dominated, and T1-T2 dual-mode MRI contrast agents with much higher contrast enhancement than the corresponding conventional iron oxide nanoparticles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02680b

Huang, Guoming; Li, Hui; Chen, Jiahe; Zhao, Zhenghuan; Yang, Lijiao; Chi, Xiaoqin; Chen, Zhong; Wang, Xiaomin; Gao, Jinhao

2014-08-01

121

Nanoparticles of Molybdenum Chlorophyllin Photosensitizer and Magnetic Citrate-Coated Cobalt Ferrite Complex Available to Hyperthermia and Photodynamic Therapy Clinical Trials  

Microsoft Academic Search

This study report on the synthesis and characterization of molybdenum chlorophyllin (Mo-Chl) compounds associated in a complex with magnetic nanoparticles (citrate-coated cobalt ferrite), the latter prepared as a biocompatible magnetic fluid (MF). The complex material was developed for application as a synergic drug for cancer treatment using Photodynamic Therapy (PDT) and Hyperthermia (HPT). Chlorophyllin was obtained from alkaline extraction of

Fernando L. Primo; Paloma L. A. G. Cordo; Alberto F. Neto; Paulo C. Morais; Antonio C. Tedesco

2010-01-01

122

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

123

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

124

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

125

High frequency magneto-dielectric effects in self-assembled ferrite-ferroelectric core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

Magneto-dielectric effects in self-assembled core-shell nanoparticles of nickel ferrite (NFO) and barium titanate (BTO) have been investigated in the millimeter wave frequencies. The core-shell nano-composites were synthesized by coating 100 nm nickel ferrite and 50 nm barium titanate nanoparticles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst forming heterogeneous nanocomposites. Magneto-electric (ME) characterization of as-assembled particles has been carried out by measurements of the relative permittivity ?r as a function of frequency f under an applied static magnetic field H over 16-24 GHz. Measurements show an H-induced decrease in ?r of 1 to 1.5%. But a giant magneto-dielectric effect with an H-induced change in permittivity as high as 28% is measured under dielectric resonance in the samples. A strong ME coupling was also evident from H-tuning of dielectric resonance in the composites. A theory for the high frequency magneto-dielectric effect has been developed and consists of the following steps. First the Bruggeman model is used to estimate the effective dielectric constant for the shell consisting of the BTO particles and voids considered as spherical air-pores. Then the permittivity for the core and shell is estimated taking into consideration the sample porosity. Finally the H-dependence of the permittivity due to ME interactions is calculated from the free energy considerations. Estimated ?r vs. H and dielectric resonance frequency vs. H characteristics are in general agreement with the data.

Popov, M.; Sreenivasulu, G.; Petrov, V. M.; Chavez, F. A.; Srinivasan, G.

2014-09-01

126

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

127

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.

128

Manganese Based Oxidative Technologies For Water/Wastewater Treatment  

E-print Network

and structural properties of ferrites. These laboratory prepared catalysts were thoroughly characterized using XRD, SEM, TEM, HR-TEM, and BET. Their magnetic properties have also been studied. These manganese ferrites offer the potential to enhance hydroxyl...

Desai, Ishan

2013-08-27

129

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

PubMed Central

Summary 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 Cr3+ and Cr2O7 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

2012-01-01

130

Characterization of oxide nanoparticles in Al-free and Al-containing oxide dispersion strengthened ferritic steels.  

PubMed

Oxide nanoparticles in oxide dispersion strengthened (ODS) ferritic steels with and without Al have been characterized by transmission electron microscopy. It is confirmed that most of the complex oxide particles consist of Y2TiO5 for 18Cr-ODS steel and YAlO3 or YAl5O12 for 18Cr5Al-ODS steel, respectivley. The addition of 5% Al in 18Cr-ODS steel leads to the formation of larger oxide particles and the reduction in their number density. For 18Cr-ODS steel, 87% of the oxide particles are coherent. The misfit strain of the coherent particles and a few semi-coherent particles is about 0.034 and 0.056, respectively. For 18Cr5Al-ODS steel, 75% of the oxide particles are semi-coherent, of which the misfit strain is 0.091 and 0.125, respectively. These results suggest that for the Al-containing ODS steel the Al addition accelerates the formation of semi-coherent oxide particles and its larger coherent and semi-coherent particles result in the larger misfit strain between the oxide particle and alloy matrix, indicating that the coherence of oxide nanoparticles in ODS steels is size-dependent. PMID:24205622

Lee, Jae Hoon; Kim, Jeoung Han

2013-09-01

131

Structural and magnetic investigations of sub-nano Mn-Mg ferrite prepared by wet method  

NASA Astrophysics Data System (ADS)

Manganese-magnesium ferrite nanoparticles Mn1-xMgxFe2O4; 0?x?0.25 were prepared by the co-precipitation route. The samples were characterized by X-ray diffraction (XRD), which confirms the single phase spinel structure. Crystallite size, calculated from the (3 1 1) peak using the Scherrer formula, was found to increase with increasing Mg2+ concentrations and was found to be within the range 3-6 nm. TEM was also used to characterize the microstructure of nanosized Mn1-xMgxFe2O4. Nominal composition of the samples was determined by Atomic Absorption analysis (AA). Hysteresis loops of manganese-magnesium ferrite were obtained at room temperature and revealed lower saturation magnetization values associated with nanocrystalline Mn1-xMgxFe2O4 particles. This behavior was attributed to structural distortion of surface spins compared to that of the bulk one.

Mansour, S. F.

2011-07-01

132

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

133

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 NixCo?-xFe?O? (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 Co?.?Ni?.?Fe?O? (154.02 m(2) g(-1)). Co?.?Ni?.?Fe?O? showed the best catalytic activity for reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 as reducing agent, whereas CoFe?O? was found to be catalytically inactive. The reduction reaction followed pseudo-first order kinetics. The effect of varying the concentration of catalyst and NaBH? 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 NiFe?O? nanoparticles as catalyst. PMID:24902783

Singh, Charanjit; Goyal, Ankita; Singhal, Sonal

2014-07-21

134

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

135

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

136

Nanoparticles of zinc sulfide doped with manganese, nickel and copper as nanophotocatalyst in the degradation of organic dyes.  

PubMed

Nanoparticles of zinc sulfide as undoped and doped with manganese, nickel and copper were used as photocatalyst in the photodegradation of methylene blue and safranin as color pollutants. Photoreactivity of doped zinc sulfide was varied with dopant, mole fraction of dopant to zinc ion, pH of solution, dosage of photocatalyst and concentration of dye. The characterization of nanoparticles was studied using X-ray powder diffraction (XRD) patterns and UV-vis spectra. The maximum degradation efficiency was obtained in the presence of Zn(0.98)Mn(0.02)S, Zn(0.94)Ni(0.06)S and Zn(0.90)Cu(0.10)S as nanophotocatalyst. The effect of dosage of photocatalyst was studied in the range of 20-250 mg/L. It was seen that 150.0 mg/L of photocatacyst is an optimum value for the dosage of photocatalyst. The most degradation efficiency was obtained in alkaline pH of 11.0 with study of photodegradation in pH amplitude of 2-12. The degradation efficiency was decreased in dye concentrations above of 5.0 mg/L for methylene blue and safranin dyes. In the best conditions, the degradation efficiency was obtained 87.3-95.6 and 85.4-93.2 for methylene blue and safranin, respectively. PMID:18603365

Pouretedal, Hamid Reza; Norozi, Abbas; Keshavarz, Mohammad Hossein; Semnani, Abolfazl

2009-03-15

137

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

Microsoft Academic Search

Manganese oxides particularly Mn3O4 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 Mn3O4, a

L. Laffont; P. Gibot

2010-01-01

138

Y 2O 3 nano-particle formation in ODS ferritic steels by Y and O dual ion-implantation  

NASA Astrophysics Data System (ADS)

For basic understanding of how to produce a homogeneous distribution of nano-scale oxide particles, we have applied dual ion-implantation to make a super-saturation of oxide-forming elements. Y + and O + ions were implanted into ferritic alloys at room temperature. Both in situ annealing in an electron microscope for thin samples and conventional annealing for bulk samples were carried out at 300-1300 K. Nano-particles of Y 2O 3 precipitated during annealing, where the starting temperatures for the nucleation and growth depended on the annealing methods. In thin specimens the growth and nucleation of Y 2O 3 started at 573 and 613 K. In bulk specimens, the growth and nucleation shifted to higher temperatures. Compared with conventional Mechanical Alloying, it is concluded that dual ion-implantation can produce much finer distributions of nano-scale oxides. In order to explain these results, we emphasize the roles of super-saturated elements and lattice defects.

Sakuma, D.; Yamashita, S.; Oka, K.; Ohnuki, S.; Rehn, L. E.; Wakai, E.

2004-08-01

139

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

140

Zinc ferrite nanoparticles as MRI contrast agentsw Carlos Ba rcena,a  

E-print Network

Feridexs . Magnetic resonance imaging (MRI) is a powerful clinical imaging technique for the non on acquiring biological specificity of SPIO by surface modifications,2,3 it still remains an open challenge of Zn-SPIO nanoparticles is the reduced toxicity of Zn over Mn. For example, the Food and Drug

Gao, Jinming

141

Evaluation of iron-cobalt\\/ferrite core-shell nanoparticles for cancer thermotherapy  

Microsoft Academic Search

Magnetic nanoparticles (MNPs) offer promise for local hyperthermia or thermoablative cancer therapy. Magnetic hyperthermia uses MNPs to heat cancerous regions in an rf field. Metallic MNPs have larger magnetic moments than iron oxides, allowing similar heating at lower concentrations. By tuning the magnetic anisotropy in alloys, the heating rate at a particular particle size can be optimized. Fe–Co core-shell MNPs

A. H. Habib; C. L. Ondeck; P. Chaudhary; M. R. Bockstaller; M. E. McHenry

2008-01-01

142

Evaluation of iron-cobalt\\/ferrite core-shell nanoparticles for cancer thermotherapy  

Microsoft Academic Search

Magnetic nanoparticles (MNPs) offer promise for local hyperthermia or thermoablative cancer therapy. Magnetic hyperthermia uses MNPs to heat cancerous regions in an rf field. Metallic MNPs have larger magnetic moments than iron oxides, allowing similar heating at lower concentrations. By tuning the magnetic anisotropy in alloys, the heating rate at a particular particle size can be optimized. Fe-Co core-shell MNPs

A. H. Habib; C. L. Ondeck; P. Chaudhary; M. R. Bockstaller; M. E. McHenry

2008-01-01

143

Field dependent transition to the non-linear regime in magnetic hyperthermia experiments: Comparison between maghemite, copper, zinc, nickel and cobalt ferrite nanoparticles of similar sizes  

NASA Astrophysics Data System (ADS)

Further advances in magnetic hyperthermia might be limited by biological constraints, such as using sufficiently low frequencies and low field amplitudes to inhibit harmful eddy currents inside the patient's body. These incite the need to optimize the heating efficiency of the nanoparticles, referred to as the specific absorption rate (SAR). Among the several properties currently under research, one of particular importance is the transition from the linear to the non-linear regime that takes place as the field amplitude is increased, an aspect where the magnetic anisotropy is expected to play a fundamental role. In this paper we investigate the heating properties of cobalt ferrite and maghemite nanoparticles under the influence of a 500 kHz sinusoidal magnetic field with varying amplitude, up to 134 Oe. The particles were characterized by TEM, XRD, FMR and VSM, from which most relevant morphological, structural and magnetic properties were inferred. Both materials have similar size distributions and saturation magnetization, but strikingly different magnetic anisotropies. From magnetic hyperthermia experiments we found that, while at low fields maghemite is the best nanomaterial for hyperthermia applications, above a critical field, close to the transition from the linear to the non-linear regime, cobalt ferrite becomes more efficient. The results were also analyzed with respect to the energy conversion efficiency and compared with dynamic hysteresis simulations. Additional analysis with nickel, zinc and copper-ferrite nanoparticles of similar sizes confirmed the importance of the magnetic anisotropy and the damping factor. Further, the analysis of the characterization parameters suggested core-shell nanostructures, probably due to a surface passivation process during the nanoparticle synthesis. Finally, we discussed the effect of particle-particle interactions and its consequences, in particular regarding discrepancies between estimated parameters and expected theoretical predictions.

Verde, E. L.; Landi, G. T.; Carrião, M. S.; Drummond, A. L.; Gomes, J. A.; Vieira, E. D.; Sousa, M. H.; Bakuzis, A. F.

2012-09-01

144

Exchange bias properties and surface spin freezing in magnetic nanoparticles  

Microsoft Academic Search

ZFC and FC magnetization measurements versus field are carried out on manganese ferrite based nanoparticles with a mean diameter of 3.3 nm. The exchange bias field determined from the field shift of hysteresis loops, decreases as the cooling field increases. Magnetization measurements performed at constant applied field H as a function of temperature allows us to separate two H-dependent contributions. One

F. G. Silva; R. Aquino; J. Depeyrot; F. A. Tourinho; V. Dupuis; R. Perzynski

2010-01-01

145

Synthesis and photoluminescent and nonlinear optical properties of manganese doped ZnS nanoparticles  

NASA Astrophysics Data System (ADS)

In this work we synthesized ZnS:Mn 2+ nanoparticles by chemical method using PVP (polyvinylpyrrolidone) as a capping agent in aqueous solution. The structure and optical properties of the resultant product were characterized using UV-vis optical spectroscopy, X-ray diffraction (XRD), photoluminescence (PL) and z-scan techniques. UV-vis spectra for all samples showed an excitonic peak at around 292 nm, indicating that concentration of Mn 2+ ions does not alter the band gap of nanoparticles. XRD patterns showed that the ZnS:Mn 2+ nanoparticles have zinc blende structure with the average crystalline sizes of about 2 nm. The room temperature photoluminescence (PL) spectrum of ZnS:Mn 2+ exhibited an orange-red emission at 594 nm due to the 4T 1- 6A 1 transition in Mn 2+. The PL intensity increased with increase in the Mn 2+ ion concentration. The second-order nonlinear optical properties of nanoparticles were studied using a continuous-wave (CW) He-Ne laser by z-scan technique. The nonlinear refractive indices of nanoparticles were in the order of 10 -8 cm 2/W with negative sign and the nonlinear absorption indices of these nanoparticles were obtained to be about 10 -3 cm/W with positive sign.

Nazerdeylami, Somayeh; Saievar-Iranizad, Esmaiel; Dehghani, Zahra; Molaei, Mehdi

2011-01-01

146

Pd on amine-terminated ferrite nanoparticles: a complete magnetically recoverable facile catalyst for hydrogenation reactions.  

PubMed

[structure: see text]. The present communication reports a facile route for Pd(0) immobilization on the surface of amine-terminated Fe3O4 and NiFe2O4 nanoparticles for a series of hydrogenation reactions. The catalysts are completely recoverable with the simple application of an external magnetic field, and the efficiency of the catalyst remains unaltered even after 10 repeated cycles for each of the reactions. PMID:17323965

Guin, Debanjan; Baruwati, Babita; Manorama, Sunkara V

2007-03-29

147

Structural refinement analysis of bulk Zn-ferrite obtained from sintering of its nanoparticles  

NASA Astrophysics Data System (ADS)

The structural refinements were performed on the samples sintered from ZnFe2O4 nanoparticles of average crystallite size (d) ranged 2 to 12 nm. The X-ray diffraction (XRD) patterns showed single phase spinel structure for all sintered samples except the sample sintered from the d = 2 nm particles. This sample showed minor impurity phase of R-3C space group.

Thirupathi, G.; Singh, R.

2013-02-01

148

Magnetic and optical properties of ionic ferrofluids based on nickel ferrite nanoparticles  

Microsoft Academic Search

New ionic ferrofluids containing NiFe2O4 nanoparticles of size <=10 nm are investigated. The crystalline structure of the particles is probed by transmission electron microscopy and x-ray scattering. Static magnetization and field-induced birefringence measurements are performed on three samples differing by particle volume fraction. Cross analyzing of the results of those two types of macroscopic tests completely rejects a simple single-domain

E. Hasmonay; J. Depeyrot; M. H. Sousa; F. A. Tourinho; J.-C. Bacri; R. Perzynski; Yu. L. Raikher; I. Rosenman

2000-01-01

149

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

NASA Astrophysics Data System (ADS)

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.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. Electronic supplementary information (ESI) available: Fig. S1-S6. See DOI: 10.1039/c3nr04378a

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

2013-12-01

150

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

151

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

152

Evaluation of iron-cobalt/ferrite core-shell nanoparticles for cancer thermotherapy  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles (MNPs) offer promise for local hyperthermia or thermoablative cancer therapy. Magnetic hyperthermia uses MNPs to heat cancerous regions in an rf field. Metallic MNPs have larger magnetic moments than iron oxides, allowing similar heating at lower concentrations. By tuning the magnetic anisotropy in alloys, the heating rate at a particular particle size can be optimized. Fe-Co core-shell MNPs have protective CoFe2O4 shell which prevents oxidation. The oxide coating also aids in functionalization and improves biocompatibility of the MNPs. We predict the specific loss power (SLP) for FeCo (SLP ˜450W /g) at biocompatible fields to be significantly larger in comparision to oxide materials. The anisotropy of Fe-Co MNPs may be tuned by composition and/or shape variation to achieve the maximum SLP at a desired particle size.

Habib, A. H.; Ondeck, C. L.; Chaudhary, P.; Bockstaller, M. R.; McHenry, M. E.

2008-04-01

153

Zn-doping effect on the energy barrier to magnetization reversal in superparamagnetic nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Measurements of ac-susceptibility and dc-magnetization were carried out on samples of Ni1-xZnxFe2O4 nanoparticles (x=0, 0.25, 0.5, 0.75) with average diameters ?7 nm. Values of the superparamagnetic blocking temperature T¯B were obtained from the characteristic temperature behavior of the imaginary susceptibility ?imag. An Arrhenius-type law, which accurately describes the relationship between the observation time ?obs and the blocking temperature, was used to determine the effective energy barrier to magnetization reversal Ueff. A Zn-content dependence of the energy barrier is observed, where Ueff changes little for 0?x?0.25, it peaks at x=0.5, and decreases back upon further Zn-doping. The large increase of Ueff at x=0.5 is attributed to an enhanced magnetic anisotropy induced by the crossover between two spatial arrangements of spins in the A and B sub-lattices of the ferrimagnetic inverse spinel.

Elizalde Galindo, J. T.; Adair, A. H.; Botez, C. E.; Corral Flores, V.; Bueno Baques, D.; Fuentes Cobas, L.; Matutes-Aquino, J. A.

2007-06-01

154

Mineral of the month: manganese  

USGS Publications Warehouse

Manganese is one of the most important ferrous metals and one of the few for which the United States is totally dependent on imports. It is a black, brittle element predominantly used in metallurgical applications as an alloying addition, particularly in steel and cast iron production, which together provide the largest market for manganese (about 83 percent). It is also used as an alloy with nonferrous metals such as aluminum and copper. Nonmetallurgical applications of manganese include battery cathodes, soft ferrite magnets used in electronics, micronutrients found in fertilizers and animal feed, water treatment chemicals, and a colorant for bricks and ceramics.

Corathers, Lisa

2005-01-01

155

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

156

Characterization, activity and mechanisms of a visible light driven photocatalyst: Manganese and iron co-modified TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

An attempt was made to prepare Mn,Fe-codoped nanostructured TiO2 photocatalyst for visible light assisted degradation of an azo dye (methylene blue) in aqueous solutions by a sol-gel process. The asprepared nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL) techniques. The photocatalytic activity of Mn,Fe-codoped TiO2 catalyst was evaluated by measuring degradation rates of methylene blue (MB) under visible light. The results showed that doping with the manganese and iron ions significantly enhanced the photocatalytic activity for MB degradation under visible light irradiation. This was ascribed to the fact that a small amount of manganese and iron dopants simultaneously increased MB adsorption capacity and separation efficiency of electron-hole pairs. The results of DRS showed that Mn,Fe-codoped TiO2 had significant absorption between 400 and 500 nm, which increased with the increase of manganese ion content. It is found that the stronger the PL intensity, the higher the photocatalytic activity. This could be explained by the points that PL spectra mainly resulted from surface oxygen vacancies and defects during the process of PL, while surface oxygen vacancies and defects could be favorable in capturing the photoinduced electrons during the process of photocatalytic reactions, so that the recombination of photoinduced electrons and holes could be effectively inhibited.

Zhang, Dongfang; Zeng, Fanbin

2011-10-01

157

X-ray powder diffraction line broadening analysis and magnetism of interacting ferrite nanoparticles obtained from acetylacetonato complexes  

Microsoft Academic Search

A study of the microstructures and magnetic properties of nanosize Zn ferrite (ZnFe2O4), Mn ferrite (MnFe2O4), and the cation deficit Zn-Mn ferrites Zn0.70Mn0.23Fe1.89O4 (S1), Zn0.41Mn0.50Fe1.84O4 (S2) and Zn0.18Mn0.67Fe1.85O4 (S3) was performed. The crystallite size for all samples was determined by x-ray powder diffraction (XRPD) analysis using four different methods, and was close to the particle size found from transmission electron

A. Kremenovic; B. Antic; V. Spasojevic; M. Vucinic-Vasic; Z. Jaglicic; J. Pirnat; Z. Trontelj

2005-01-01

158

Nanoparticles of Molybdenum Chlorophyllin Photosensitizer and Magnetic Citrate-Coated Cobalt Ferrite Complex Available to Hyperthermia and Photodynamic Therapy Clinical Trials  

NASA Astrophysics Data System (ADS)

This study report on the synthesis and characterization of molybdenum chlorophyllin (Mo-Chl) compounds associated in a complex with magnetic nanoparticles (citrate-coated cobalt ferrite), the latter prepared as a biocompatible magnetic fluid (MF). The complex material was developed for application as a synergic drug for cancer treatment using Photodynamic Therapy (PDT) and Hyperthermia (HPT). Chlorophyllin was obtained from alkaline extraction of Ilex paraguariensis following molybdenum insertion from hydrolysis with molybdate sodium. Fluorescence quantum yield (?f) of Mo-Chl/dimethyl-sulphoxide (DMSO) was lower than 0.1, with a lifetime of 5.0 ns, as obtained from time-correlated single-photon counting technique. The oxygen quantum yield of Mo-Chl was carried out using laser flash-photolysis studies in homogeneous medium saturated with O2(g) (?? = 0.50). Cellular viability was also evaluated via the classical MTT assay using gingival fibroblasts cells as a biological model. Studies performed with the complex Mo-Chl (5.0 ?mol.L-1)/MF at different magnetic nanoparticle concentrations (ranging from 1012 to 1015 particle.mL-1) revealed a cellular viability of approximately 95% for the ideal magnetic material concentration of 1×10 particle.mL-1. The present study shows that natural photosensitizers molecules Mo-Chl used in association with magnetic nanoparticles represent a promising generation of drug developed to work synergistically in the treatment of neoplastic tissues using PDT and HPT.

Primo, Fernando L.; Cordo, Paloma L. A. G.; Neto, Alberto F.; Morais, Paulo C.; Tedesco, Antonio C.

2010-12-01

159

Mesoporous Silica-Coated Hollow Manganese Oxide Nanoparticles as Positive T1 Contrast Agents for Labeling and MRI Tracking of Adipose-Derived Mesenchymal Stem Cells  

PubMed Central

Mesoporous silica-coated hollow manganese oxide (HMnO@mSiO2) nanoparticles were developed as a novel T1 magnetic resonance imaging (MRI) contrast agent. We hypothesized that the mesoporous structure of the nanoparticle shell enables optimal access of water molecules to the magnetic core, and consequently, an effective longitudinal (R1) relaxation enhancement of water protons, which value was measured to be 0.99 (mM?1s?1) at 11.7 T. Adipose-derived mesenchymal stem cells (MSCs) were efficiently labeled using electroporation, with much shorter T1 values as compared to direct incubation without electroporation, which was also evidenced by signal enhancement on T1-weighted MR images in vitro. Intracranial grafting of HMnO@mSiO2-labeled MSCs enabled serial MR monitoring of cell transplants over 14 days. These novel nanoparticles may extend the arsenal of currently available nanoparticle MR contrast agents by providing positive contrast on T1-weighted images at high magnetic field strengths. PMID:21314118

2011-01-01

160

Sol-gel synthesis and characterization of pure and manganese doped TiO2 nanoparticles--a new NLO active material.  

PubMed

Pure and Manganese (4%, 8%, 12% and 16%) doped titanium di-oxide (Mn-TiO2) nanoparticles were synthesized by sol-gel technique. The preparation of pure and Mn doped TiO2 nanoparticles were achieved by tetra-isopropyl orthotitanate and 2-propanol as common starting materials and the products were annealed at 450°C and 750°C to get anatase and rutile phases, respectively. The prepared materials were characterized by X-ray diffraction analysis (XRD), Fourier transform infra-red spectroscopy (FT-IR), UV-VIS-Diffuse reflectance spectroscopy (DRS), Photoluminescence (PL) spectroscopy, Scanning electron microscopy (SEM) with Energy dispersive X-ray analysis (EDX) and Kurtz powder second harmonic generation (SHG) test. XRD patterns confirmed the crystalline nature and tetragonal structure of synthesized materials. The functional groups present in the samples were identified by FTIR study. The allowed direct and indirect band gap energies, as well as the crystallite sizes of obtained nanoparticles were calculated from DRS analysis. Microstructures and elemental identification were done by SEM with EDX analysis. The existence of SHG signals was observed using Nd: YAG laser with fundamental wavelength of 1064 nm. The products were found to be transparent in the entire visible region with cut-off wavelengths within the UV region confirms its suitability for device fabrications. PMID:24374482

Praveen, P; Viruthagiri, G; Mugundan, S; Shanmugam, N

2014-01-01

161

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

PubMed Central

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 and tissue magnetic targeting. Nanoparticle cytotoxicity to Saos-2 cells was investigated using the MTT assay. To guide the external magnetic field in the liver, the concentration of As2O3 in the liver and kidney was measured using an atomic fluorescence spectrometer after injecting As2O3-MNPs into the caudal veins of mice. Results: The As2O3-MNPs were approximately spherical. The average diameter, drug loading, entrapment efficiency and zeta potential of As2O3-MNPs were 109.9 nm, 10.08%, 82.16%, and ?14.33 mV, respectively. The specific saturation magnetism was 8.65 emu/g. In vivo, the concentration of As2O3 in the liver was significantly higher than that in the non-magnetic group. While the concentration of As2O3 in the kidney was lower than that in the non-magnetic group. The Cmax in liver tissue in the magnetic group was 30.65 ?g/g, which was 4.17 times the drug concentration in the same group in kidney tissue (7.35 ?g/g) and 2.88 times the concentration of drug (10.66 ?g/g) in the liver tissue of the non-magnetic group. Conclusion: The PLGA polymer-loaded magnetic nanoparticle composed of arsenic trioxide can be magnetically targeted well and applied in biomedicine. PMID:19960013

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

2009-01-01

162

Controlled oxidation of FeCo magnetic nanoparticles to produce faceted FeCo/ferrite nanocomposites for rf heating applications  

E-print Network

for rf heating applications K. N. Collier,1,2 N. J. Jones,1 K. J. Miller,1 Y. L. Qin,1 D. E. Laughlin,1 for polydisperse FeCo magnetic nanoparticles MNPs synthesized using an induction plasma torch. X-ray diffraction the FeCo core and oxide shell. We show HRTEM images of MNP chaining and compare the rf heating of samples

Laughlin, David E.

163

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

164

Comparison study of the magnetic permeability and dc conductivity of Co-Ni-Li ferrite nanoparticles and their bulk counterparts  

NASA Astrophysics Data System (ADS)

The temperature dependence of relative permeability and dc electrical conductivity of nanosamples and their bulk counterparts of Co0.5Ni0.5-2xLixFe2+xO4 (from x=0.00 to 0.25 in step of 0.05) was investigated. The values of the relative permeability of the nano-samples are lower than their bulk counterparts as a result of porous and nano-grained structure besides the effect of the larger volume of grain boundaries in the nanosamples. Moreover, the dc conductivity of the nanosamples is higher than their bulk counterparts. This is probable explained according to the shorter metal-oxygen bonding length and higher lattice vibrations of the nanosamples. Also, the values of the relative permeability of both nano and bulk samples exhibit stability over a considerable range of temperatures. This may make them useful in practical applications that require stability. All the nanosamples show high rising Curie temperature values with increasing the Li content up to the sample of x=0.15 thereafter a decrease of the Curie temperature occurs while the inverse behavior was observed in their bulk counterparts. The interpretation of these findings is explained in the discussion. Moreover, in general doping Co-Ni ferrites with Li ions improves their electrical and magnetic properties and this is clearly observed in the nanosample of x=0.15 which can be regarded as the most promising sample for microwave applications.

Assar, S. T.; Abosheiasha, H. F.; El Nimr, M. K.

2014-03-01

165

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. PMID:22296968

2012-01-01

166

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

167

Silver-doped manganese dioxide and trioxide nanoparticles inhibit both gram positive and gram negative pathogenic bacteria.  

PubMed

Palladium, ruthenium and silver-doped MnO2 and silver doped Mn2O3 nanoparticles were synthesized by simple co-precipitation technique. SEM-TEM analysis revealed the nano-size of these synthesized samples. XPS data illustrates that Mn is present in 4+ and 3+ oxidation states in MnO2 and Mn2O3 respectively. Thermal analysis gave significant evidence for the phase changes with increasing temperature. Antibacterial activity of these synthesized nanoparticles on three Gram positive bacterial cultures (Staphylococcus aureus ATCC 6538, Streptococcus epidermis ATCC 12228, Bacillus subtilis ATCC 6633) and three Gram negative cultures (Escherichia coli ATCC 8739, Salmonella abony NCTC 6017 and Klebsiella pneumoniae ATCC 1003) was investigated using a disc diffusion method and live/dead assay. Only Ag-doped MnO2 and Ag-doped Mn2O3 nanoparticles showed antibacterial property against all six-test bacteria but Ag-doped MnO2 was found to be more effective than Ag-doped Mn2O3. PMID:24140741

Kunkalekar, R K; Prabhu, M S; Naik, M M; Salker, A V

2014-01-01

168

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

169

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

170

Synthesis and Characterization of a Novel Extracellular Biogenic Manganese Oxide (Bixbyite-like Mn 2 O 3 ) Nanoparticle by Isolated Acinetobacter sp  

Microsoft Academic Search

Recently, manganese oxides have been considered in the environmental remediation, MRI diagnosis and drug and pharmaceutical\\u000a industries. Different numbers of physicochemical and biological methods have been reported for the preparation of nanoscale\\u000a manganese oxides. Although manganese oxide biogenesis by bacterial species has been recognized as the major Mn-oxidizing agent\\u000a in nature, in this research, for first time, we demonstrated the

Baharak Hosseinkhani; Giti Emtiazi

171

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

NASA Astrophysics Data System (ADS)

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 ferrite with a saturation magnetization (MS) of 58.8 emu/g.

Liu, Chung?Wen; Lin, Cheng?Hsiung; Fu, Yen?Pei

2006-05-01

172

Predictive Toxicology of cobalt ferrite nanoparticles: comparative in-vitro study of different cellular models using methods of knowledge discovery from data  

PubMed Central

Background Cobalt-ferrite nanoparticles (Co-Fe NPs) are attractive for nanotechnology-based therapies. Thus, exploring their effect on viability of seven different cell lines representing different organs of the human body is highly important. Methods The toxicological effects of Co-Fe NPs were studied by in-vitro exposure of A549 and NCIH441 cell-lines (lung), precision-cut lung slices from rat, HepG2 cell-line (liver), MDCK cell-line (kidney), Caco-2 TC7 cell-line (intestine), TK6 (lymphoblasts) and primary mouse dendritic-cells. Toxicity was examined following exposure to Co-Fe NPs in the concentration range of 0.05 -1.2 mM for 24 and 72 h, using Alamar blue, MTT and neutral red assays. Changes in oxidative stress were determined by a dichlorodihydrofluorescein diacetate based assay. Data analysis and predictive modeling of the obtained data sets were executed by employing methods of Knowledge Discovery from Data with emphasis on a decision tree model (J48). Results Different dose–response curves of cell viability were obtained for each of the seven cell lines upon exposure to Co-Fe NPs. Increase of oxidative stress was induced by Co-Fe NPs and found to be dependent on the cell type. A high linear correlation (R2=0.97) was found between the toxicity of Co-Fe NPs and the extent of ROS generation following their exposure to Co-Fe NPs. The algorithm we applied to model the observed toxicity belongs to a type of supervised classifier. The decision tree model yielded the following order with decrease of the ranking parameter: NP concentrations (as the most influencing parameter), cell type (possessing the following hierarchy of cell sensitivity towards viability decrease: TK6 > Lung slices > NCIH441 > Caco-2?=?MDCK > A549 > HepG2?=?Dendritic) and time of exposure, where the highest-ranking parameter (NP concentration) provides the highest information gain with respect to toxicity. The validity of the chosen decision tree model J48 was established by yielding a higher accuracy than that of the well-known “naive bayes” classifier. Conclusions The observed correlation between the oxidative stress, caused by the presence of the Co-Fe NPs, with the hierarchy of sensitivity of the different cell types towards toxicity, suggests that oxidative stress is one possible mechanism for the toxicity of Co-Fe NPs. PMID:23895432

2013-01-01

173

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. PMID:22654621

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

2012-01-01

174

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

NASA Astrophysics Data System (ADS)

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).

Refat, Moamen S.

2014-12-01

175

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

176

Thermal plasma synthesis of nanocrystalline ferrite particles  

NASA Astrophysics Data System (ADS)

Highly functional soft magnetic materials have received a dramatically growing interest in the last two decades, along with amazing technological advances in electronics and telecommunications. Among soft magnetic materials ferrites are important and promising candidates for use at high frequencies because of their high resistivities. There has been another important development towards better soft magnetic materials, which is nanostructured materials technology. As a result of an ultrafine grain size and consequent large volume fraction of atoms occupying the interfacial regions, nanocrystalline materials show interesting properties that are often different from those of conventional bulk materials. Nanocrystalline ferrite materials are novel candidates for high-frequency soft magnetic applications because of their higher resistivities than metallic counterparts and of grain size dependent magnetic properties. For the first time, RF plasma torch synthesis of a series of ferrite nanoparticles using metallic precursor powders was carried out in this study. Microstructural and magnetic properties of the as-synthesized powders were examined. The viability of plasma torch synthesis for production of ferrite nanoparticles has been demonstrated over the results. Magnetite, Ni-, NiZn-, Mn-, and MnZn-ferrite have been successfully synthesized. The only oxygen source for oxide formation is the compressed air flowing through the reactor. The average grain sizes of the plasma-torched powders are in the range of 10--30 nm, with a standard deviation of ˜10 nm. Their stoichiometries are slightly off from the desired ones. These ferrite nanoparticles had well-defined polygonal growth shapes showing (100) and (111) faceting. Most of them are truncated octahedral or truncated cubic shapes. Some theoretical calculations based on the cuboctahedron model revealed that the surface energy ratio of (100) to (111) planes, gamma100/gamma111, must have a value between 0.577 and 1.732 under the assumption of the same edge length. EXAFS analysis was helpful to determine the interstitial site occupation by the metallic cations in the ferrites and to reveal that there is a surface truncation of the lattice. Mossbauer analysis of the ferrite nanoparticles showed that Zn addition to the ferrite structure decreases the hyperfine magnetic fields of both sublattices and increases in the fraction of superparamagnetic particles.

Son, Suk-Joon

177

Contaminant Transformation by a Biogenic Manganese Oxide  

NASA Astrophysics Data System (ADS)

Biomineralization of manganese by Pseudomonas putida strain MnB1 produces tetravalent manganese oxides that surround the exterior of the bacterial cell. The manganese oxides produced by P. putida transform the herbicide atrazine, a widespread environmental contaminant, by dechlorination, dealkylation and deamination reactions. The transformation reactions catalyzed by biogenic manganese oxide surfaces create a suite of transformation intermediates whose properties, such as aqueous solubility, toxicity and biodegradability, differ dramatically from those of the parent compound. The rates and products of atrazine transformation by biogenic manganese oxide surfaces were examined as functions of temperature and water potential. Air-dry samples of hydrous manganese oxide (? -MnO2) and biogenic manganese oxide were isopiestically equilibrated to -3.10, -0.50 and -0.04 MPa at 40 degrees Celsius and to -0.04 MPa at 20 and 30 degrees Celcius. The concentrations of atrazine and eight transformation intermediates were determined by HPLC. Our results suggest that biogenic manganese oxides may contribute greatly to the detoxification and immobilization of organic contaminants in the environment because of their nanoparticle size, large surface area and high chemical reactivity.

Toner, B. M.; Sposito, G.

2001-12-01

178

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

179

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

180

Ferrite devices and materials  

Microsoft Academic Search

The development and current status of microwave ferrite technology is reviewed in this paper. An introduction to the physics and fundamentals of key ferrite devices is provided, followed by a historical account of the development of ferrimagnetic spinel and garnet (YIG) materials. Key ferrite components, i.e., circulators and isolators, phase shifters, tunable filters, and nonlinear devices are also discussed separately

J. Douglas Adam; Lionel E. Davis; Gerald F. Dionne; Ernst F. Schloemann; Steven N. Stitzer

2002-01-01

181

Synthesis, magnetic and optical properties of core/shell Co1- x Zn x Fe2O4/SiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

182

nanoparticles  

NASA Astrophysics Data System (ADS)

In this paper, we report the observation of intrinsic room temperature ferromagnetism in pure La2O3 nanoparticles. Magnetism measurement indicates that all of the samples exhibit room temperature ferromagnetism and the saturation magnetization for the samples decreases with the increase in annealing temperature from 700 to 1,000 °C. X-ray photoelectron spectroscopy identifies the presence of oxygen vacancies in the La2O3 nanoparticles. The fitting results of the O 1 s spectrum indicate that the variation of the oxygen vacancy concentration is in complete agreement with the change of the saturation magnetization. It is also found that the saturation magnetization of the La2O3 nanoparticles can be tuned by post-annealing in argon or oxygen atmosphere. These results suggest that the oxygen vacancies are largely responsible for the room temperature ferromagnetism in pure La2O3 nanoparticles.

Xu, Qiang; Gao, Daqiang; Zhang, Jing; Yang, Zhaolong; Zhang, Zhipeng; Rao, Jinwei; Xue, Desheng

2014-09-01

183

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

2014-09-01

184

Hot coal gas desulfurization with manganese-based sorbents. Annual report, September 1992--September 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 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. It includes the prior Quarterly Technical Reports which 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.

1993-12-01

185

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

186

nanoparticles  

NASA Astrophysics Data System (ADS)

Undoped and Zn-doped TiO2 nanoparticles were synthesized by the sol gel method. The dopant (Zn) was taken at 0.1, 0.2, 0.5, 0.7, and 1.0 mol%. The initial precursors were titanium tetraisopropoxide and zinc acetate. The samples were characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and UV-vis diffuse reflectance. The photocatalytic activity of the prepared nanoparticles was studied by observing their role in degradation of two azo dyes, i.e., Eriochrome Black T and Methyl Red under UV-visible light. The results revealed that Zn-doped TiO2 nanoparticles exhibited better degradation as compared to undoped TiO2 nanoparticles. In this study, 0.7 mol% Zn-doped TiO2 showed highest photocatalytic activity. Doping of Zn allowed better separation of electron-hole pairs which results in increased oxidation and reduction reactions.

Singla, Pooja; Sharma, Manoj; Pandey, O. P.; Singh, K.

2014-07-01

187

Comminuting irradiated ferritic steel  

DOEpatents

Disclosed is a method of comminuting irradiated ferritic steel by placing the steel in a solution of a compound selected from the group consisting of sulfamic acid, bisulfate, and mixtures thereof. The ferritic steel is used as cladding on nuclear fuel rods or other irradiated components.

Bauer, Roger E. (Kennewick, WA); Straalsund, Jerry L. (Kennewick, WA); Chin, Bryan A. (Auburn, AL)

1985-01-01

188

Comminuting irradiated ferritic steel  

SciTech Connect

Disclosed is a method of comminuting irradiated ferritic steel by placing the steel in a solution of a compound selected from the group consisting of sulfamic acid, bisulfate, and mixtures thereof. The ferritic steel is used as cladding on nuclear fuel rods or other irradiated components.

Bauer, R. E.; Chin, B. A.; Straalsund, J. L.

1985-03-26

189

nanoparticles  

NASA Astrophysics Data System (ADS)

Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

2014-10-01

190

Pharmacokinetics of intravenously injected Tc-99m labeled ferrite nanobeads  

NASA Astrophysics Data System (ADS)

We study the time varying biodistribution of ferrite (Fe3O4) nanoparticles upon in vivo injection. For this purpose, a novel process of directly labeling radioactive Tc-99m with ferrite nanoparticles was developed. The radiobeads serve as a tracer to provide information on the uptake of injected particles by organs. In the course of our study, Tc-99m labeled ferrite beads were intravenously injected into the tail vein of rats. The time course of changes in the radio-intensity of heart, lung, and liver could be achieved by real-time scintigraphic images. It was observed that the particle uptake by organs is very fast and completed within the first few minutes after intravenous injection. The pharmacokinetic behavior of the radiobead uptake was quantitatively described by a two-compartment model.

Fu, Chao-Ming; Wang, Yuh-Feng; Guo, Yu-Feng; Wang, Li-Shin; Chuang, May-Haw; Cham, Thau-Ming

2009-04-01

191

Ferrite flocculating system  

SciTech Connect

A method for removal of insoluble suspended impurities from polluted liquids by adding thereto a magnetic ferrite powder suspendible therein and a polyethyleneimine flocculant which flocculates suspended solid impurities and the magnetic powder producing a dense flocculated mixture.

Brooks, R.E.; Slusarczuk, G.M.

1980-03-18

192

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

193

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

194

46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).  

Code of Federal Regulations, 2011 CFR

...Note: For high alloy steels refer to § 54.25-15. For heat treated steels refer to § 54.25-20...67 °F., ferritic steels shall be made with fine...practice and shall have an austenitic grain size of...Max. C 1 percent Manganese range 1 percent...

2011-10-01

195

46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).  

Code of Federal Regulations, 2010 CFR

...Note: For high alloy steels refer to § 54.25-15. For heat treated steels refer to § 54.25-20...67 °F., ferritic steels shall be made with fine...practice and shall have an austenitic grain size of...Max. C 1 percent Manganese range 1 percent...

2010-10-01

196

Evolution of Microstructures During Austempering of Ductile Irons Alloyed with Manganese and Copper  

NASA Astrophysics Data System (ADS)

The influences of relatively high manganese (0.45 through 1.0 wt pct) and copper (0.56 through 1.13 wt pct) contents on microstructure development and phase transformation in three austempered ductile irons have been studied. The experimental ductile irons alloyed with copper and manganese are found to be practically free from intercellular manganese segregation. This suggests that the positive segregation of manganese is largely neutralized by the negative segregation of copper when these alloying elements are added in appropriate proportions. The drop in unreacted austenite volume (UAV) with increasing austempering temperature and time is quite significant in irons alloyed with copper and manganese. The ausferrite morphology also undergoes a transition from lenticular to feathery appearance of increasing coarseness with the increasing austempering temperature and time. SEM micrographs of the austempered samples from the base alloy containing manganese only, as well as copper plus manganese-alloyed irons, clearly reveal the presence of some martensite along with retained austenite and ferrite. X-ray diffraction analysis also confirms the presence of these phases. SEM examination further reveals the presence of twinned martensite in the copper plus manganese-alloyed samples. The possibility of strain-induced transformation of austenite to martensite during austempering heat treatment is suggested.

Dasgupta, Ranjan Kumar; Mondal, Dipak Kumar; Chakrabarti, Ajit Kumar

2013-03-01

197

Effect of filler loading of nickel zinc ferrite on the tensile properties of PLA nanocomposites  

NASA Astrophysics Data System (ADS)

The mechanical strength of magnetic polymer nanocomposite (MPNC) of nickel zinc (NiZn) ferrite nanoparticles incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer is reported. The matrix was prepared from PLA and LNR in the ratio of 90:10. The MPNC were prepared at constant mixing temperature at 180°C, mixing time of 15 min. and mixing speed of 100 rpm. In order to achieve a good dispersion of NiZn ferrite in the matrix, firstly an ultrasonic treatment had been employed to mix the LNR and NiZn ferrite for 1 hour. The MPNC of PLA/LNR/NiZn ferrite then were prepared via Thermo Haake internal mixer using melt-blending method from different filler loading from 1-5 wt% NiZn ferrite. The result of tensile tests showed that as the filler loading increases the tensile strength also increases until an optimum value of filler loading was reached. The Young's modulus, tensile strength and elongation at break have also increased. The study proves that NiZn ferrite is excellent reinforcement filler in PLA matrix. Scanning electron micrograph (SEM) and energy dispersive X-ray spectroscopy (EDX) were meant to show the homogeneity dispersion of nanoparticles within the matrix and to confirm the elemental composition of NiZn ferrites-PLA/LNR nanocomposites respectively.

Shahdan, Dalila; Ahmad, Sahrim Hj

2013-05-01

198

High Strength Ferritic Alloy.  

National Technical Information Service (NTIS)

A high-strength ferritic alloy is described which is useful for fast reactor duct and cladding applications. An iron base contains from about 9% to about 13% by weight chromium, from about 4% to about 8% by weight molybdenum, from about 0.2% to about 0.8%...

W. C. Hagel, F. A. Smidt, M. K. Korenko

1977-01-01

199

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. PMID:22784304

2012-01-01

200

Drinking Water Problems: Iron and Manganese  

E-print Network

concentrations of iron and manganese) Oxidizing filter?manganese greensand or zeolite (use with zeolite coated with manganese oxide. These substances adsorb dis- solved iron and manganese. Synthetic zeolite requires less backwash water and softens water as it removes impurities...

Dozier, Monty; McFarland, Mark L.

2004-02-20

201

Effect of Ti-containing inclusions on the nucleation of acicular ferrite and mechanical properties of multipass weld metals.  

PubMed

In the present study, the influence of Ti-containing inclusions on the development of acicular ferrite microstructure and mechanical properties in the multipass weld metals has been studied. Shielded metal arc weld deposits were prepared by varying titanium content in the range of 0.003-0.021%. The variation in the titanium content was obtained by the addition of different amounts of titanium oxide nanoparticles to the electrode coating. The dispersion of titanium oxide nanoparticles, composition of inclusions, microstructural analysis, tensile properties and Charpy impact toughness were evaluated. As the amount of Ti-containing inclusions in the weld metal was increased, the microstructure of the weld metal was changed from the grain boundary allotriomorphic ferrite structure to acicular ferrite with the intragranular nucleation of ferrite on the Ti-containing inclusions, and the mechanical properties were improved. This improvement is attributable to the increased percentage of acicular ferrite due to the uniform dispersion of Ti-containing inclusions and the pinning force of oxide nanoparticles against the growth of allotriomorphic ferrite and Widmanstätten ferrite from the austenite grain boundaries. PMID:23238108

Fattahi, M; Nabhani, N; Hosseini, M; Arabian, N; Rahimi, E

2013-02-01

202

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, David S. (West Richland, WA); Ghoniem, Nasr M. (Granada Hills, CA); Powell, Roger W. (Pasco, WA)

1986-01-01

203

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

204

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. PMID:871441

Saric, M; Markicevic, A; Hrustic, O

1977-01-01

205

Critical enhancements of MRI contrast and hyperthermic effects by dopant-controlled magnetic nanoparticles.  

PubMed

Doped up: The incorporation of Zn(2+) dopants in tetrahedral sites leads to the successful magnetism tuning of spinel metal ferrite nanoparticles (see picture). (Zn(0.4)Mn(0.6))Fe(2)O(4) nanoparticles exhibit the highest magnetization value among the metal ferrite nanoparticles. Such high magnetism results in the largest MRI contrast effects (r2=860 mm(-1) s(-1)) reported to date and also huge hyperthermic effects. PMID:19137514

Jang, Jung-tak; Nah, Hyunsoo; Lee, Jae-Hyun; Moon, Seung Ho; Kim, Min Gyu; Cheon, Jinwoo

2009-01-01

206

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

207

Synthesis and characterization of diethylenetriaminepentaacetic acid-chitosan-coated cobalt ferrite core\\/shell nanostructures  

Microsoft Academic Search

Special diethylenetriaminepentaacetic acid (DTPA)-chitosan-coated cobalt ferrite core\\/shell nanoparticles have been synthesized via a novel zero-length emulsion crosslinking process and characterized via crosslinking degree, simultaneous thermogravimetric analysis and differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared spectrometer, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and vibration sample magnetometry. The experimental results showed that the CoFe2O4 nanoparticles were really encapsulated with

Runhua Qin; Fengsheng Li; Wei Jiang; Mingyue Chen

2010-01-01

208

The effects of particle size and surface coating on the cytotoxicity of nickel ferrite.  

PubMed

The safety and toxicity of nanoparticles are of growing concern despite their significant scientific interests and promising potentials in many applications. The properties of nanoparticles depend not only on the size but also the structure, microstructure and surface coating. These in turn are controlled by the synthesis and processing conditions. The dependence of cytotoxicity on particle size and on the presence of oleic acid as surfactant on nickel ferrite particles were investigated in vitro using the Neuro-2A cell line as a model. For nickel ferrite particles without oleic acid prepared by ball milling, cytotoxicity was independent of particle size within the given mass concentrations and surface areas accessible to the cells. For nickel ferrite particles coated with oleic acid prepared by the polyol method, the cytotoxicity significantly increased when one or two layers of oleic acid were deposited. Large particles (150+/-50 nm diameter) showed a higher cytotoxicity than smaller particles (10+/-3 nm diameter). PMID:15949547

Yin, H; Too, H P; Chow, G M

2005-10-01

209

Manganese, Metallogenium, and Martian Microfossils  

NASA Technical Reports Server (NTRS)

Manganese could easily be considered an abundant element in the Martian regolith, assuming that the composition of martian meteorites reflects the composition of the planet. Mineralogical analyses of 5 SNC meteorites have revealed an average manganese oxide concentration of 0.48%, relative to the 0.1% concentration of manganese found in the Earth's crust. On the Earth, the accumulation of manganese oxides in oceans, soils, rocks, sedimentary ores, fresh water systems, and hydrothermal vents can be largely attributed to microbial activity. Manganese is also a required trace nutrient for most life forms and participates in many critical enzymatic reactions such as photosynthesis. The wide-spread process of bacterial manganese cycling on Earth suggests that manganese is an important element to both geology and biology. Furthermore, there is evidence that bacteria can be fossilized within manganese ores, implying that manganese beds may be good repositories for preserved biomarkers. A particular genus of bacteria, known historically as Metallogenium, can form star-shaped manganese oxide minerals (called metallogenium) through the action of manganese oxide precipitation along its surface. Fossilized structures that resemble metallogenium have been found in Precambrian sedimentary formations and in Cretaceous-Paleogene cherts. The Cretaceous-Paleogene formations are highly enriched in manganese and have concentrations of trace elements (Fe, Zn, Cu, and Co) similar to modern-day manganese oxide deposits in marine environments. The appearance of metallogenium-like fossils associated with manganese deposits suggests that bacteria may be preserved within the minerals that they form. Additional information is contained in the original extended abstract.

Stein, L. Y.; Nealson, K. H.

1999-01-01

210

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. PMID:21603070

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

2011-01-01

211

Tissue Manganese Concentrations in Young Male Rhesus Monkeys following Subchronic Manganese Sulfate Inhalation  

Microsoft Academic Search

High-dose human exposure to manganese results in manganese accumulation in the basal ganglia and dopaminergic neuropa- thology. Occupational manganese neurotoxicity is most frequently linked with manganese oxide inhalation; however, exposure to other forms of manganese may lead to higher body burdens. The objective of this study was to determine tissue manganese con- centrations in rhesus monkeys following subchronic (6 h\\/day,

David C. Dorman; Melanie F. Struve; Marianne W. Marshall; Carl U. Parkinson; R. Arden James; Brian A. Wong

2006-01-01

212

Superparamagnetism of transition metal nanoparticles in conducting polymer film  

NASA Astrophysics Data System (ADS)

Magnetic properties of transition metal (cobalt, iron, nickel, manganese, chromium) nanoparticles prepared by ion-exchange method in the perfluorinated sulfo-cation polymeric membrane (MF-4SK) have been investigated. While manganese and chromium in MF-4SK exhibited paramagnetic properties, cobalt, iron and nickel particles showed superparamagnetic behaviors. Our experimental evidence suggests that cobalt, iron and nickel nanoparticles in the polymer film obey a single-domain theory.

Yoon, M.; Kim, Y.; Kim, Y. M.; Yoon, H.; Volkov, V.; Avilov, A.; Park, Y. J.; Park, I.-W.

2004-05-01

213

Superparamagnetism of transition metal nanoparticles in conducting polymer film  

NASA Astrophysics Data System (ADS)

Magnetic properties of transition metal (cobalt, iron, nickel, manganese, chromium) nanoparticles prepared by ion-exchange method in the perfluorinated sulfo-cation polymeric membrane (MF-4SK) have been investigated. While manganese and chromium in MF-4SK exhibited paramagnetic properties, cobalt, iron and nickel particles showed superparamagnetic behaviors. Our experimental evidence suggests that cobalt, iron and nickel nanoparticles in the polymer film obey a single-domain theory.

Yoon, M.; Kim, Y.; Kim, Y. M.; Yoon, H.; Volkov, V.; Avilov, A.; Park, Y. J.; Park, I.-W.

214

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2013-04-01

215

21 CFR 582.5455 - Manganese glycerophosphate.  

...2014-04-01 2014-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2014-04-01

216

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2011-04-01

217

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2010-04-01

218

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2012-04-01

219

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

PubMed Central

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

2014-01-01

220

Flash microwave synthesis of trevorite nanoparticles  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named "lithium-ion" batteries. In this study, NiFe 2O 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 2O 4 nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m 2/g). Thus, microwave heating appears as an efficient source of energy to produce quickly nanoparticles with complex composition as ferrite.

Bousquet-Berthelin, C.; Chaumont, D.; Stuerga, D.

2008-03-01

221

The Structure and Properties of Plasma Sprayed Iron Oxide Doped Manganese Cobalt Oxide Spinel Coatings for SOFC Metallic Interconnectors  

Microsoft Academic Search

Manganese cobalt oxide spinel doped with Fe2O3 was studied as a protective coating on ferritic stainless steel interconnects. Chromium alloying causes problems at high\\u000a operation temperatures in such oxidizing conditions where chromium compounds evaporate and poison the cathode active area,\\u000a causing the degradation of the solid oxide fuel cell. In order to prevent chromium evaporation, these interconnectors need\\u000a a protective

Jouni Puranen; Juha Lagerbom; Leo Hyvärinen; Mikko Kylmälahti; Olli Himanen; Mikko Pihlatie; Jari Kiviaho; Petri Vuoristo

2011-01-01

222

Small high directivity ferrite antennas  

NASA Astrophysics Data System (ADS)

A centimeter-wavelength antenna of millimetric dimensions, which uses the intrinsic angular sensitivity of ferrites, is described, with an emphasis on the modification of the material's permeability. The construction of both the ferrite film lens antenna and the ferrite film cassegrain antenna are detailed; both can be devised in a number of configurations for appropriate beam positioning and rf filtering. The antenna design, discussed primarily in the context of smart missiles, electronic warfare, and satellite systems, presents the possibility of magnetically switching between the transmit and receive modes within the antenna structure itself. Finally, it is noted that for a simple 2-dipole array the angular resolution can be two orders of magnitude higher than with the conventional techniques.

Wright, T. M. B.

223

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

224

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

225

On the suitability of nanocrystalline ferrites as a magnetic carrier for drug delivery: functionalization, conjugation and drug release kinetics.  

PubMed

Superparamagnetic nickel ferrite nanoparticles functionalized with polyvinyl alcohol, polyethylene oxide and polymethacrylic acid (PMAA) polymers and subsequently conjugated with doxorubicin anti-cancer drug are studied for their use as a magnetic carrier for drug delivery. Fourier transform infrared spectroscopy enabled examination of the ability of the nanoparticles to be functionalized with polymers and conjugated with doxorubicin drug. The functionalized polymer-coated nanocrystalline nickel ferrites retain the magnetic characteristics of non-functionalized nanocrystalline nickel ferrites (superparamagnetism, absence of hysteresis, remanence and coercivity at room temperature), encouraging their application as a magnetic carrier for drug delivery. The PMAA-coated nanoferrites are demonstrated as being a potentially superior magnetically targeted drug carrier based on FTIR results and drug release kinetics in the absence and presence of an external magnetic field. PMID:17224313

Rana, S; Gallo, A; Srivastava, R S; Misra, R D K

2007-03-01

226

Mössbauer studies of nanosized ferrites prepared by the combustion of metal nitrates oxalyl dihydrazide solutions  

NASA Astrophysics Data System (ADS)

Alkaline earth metal ferrites have been prepared by combustion of redox mixtures containing metal nitrates and oxalyl dihydrazide (ODH) at 673 K. On rapid heating, ODH metal nitrate mixture undergoes an abrupt exothermic redox chemical reaction that facilitates atomic scale mixing of cations. This leads to the formation of stoichiometrically pure and single-phase nanoparticle ferrites at comparatively reduced temperature (400°C) and in less time than possible by the conventional ceramic method. Because of their different cationic size, polarizability etc., alkaline earth metal cations yield different type of ferrites i.e. MFe2O4 (M = Mg, Ba), Ca2Fe2O5 and SrFe12O19.

Gandotra, Karun; Randhawa, B. S.

2008-07-01

227

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Manganese heterocyclic tetraamine complex (generic). ...Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic). ...identified generically as manganese heterocyclic tetraamine complex (PMNs...

2010-07-01

228

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Manganese heterocyclic tetraamine complex (generic). ...Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic). ...identified generically as manganese heterocyclic tetraamine complex (PMNs...

2011-07-01

229

Biomagnetic of Apatite-Coated Cobalt Ferrite: A Core–Shell Particle for Protein Adsorption and pH-Controlled Release  

Microsoft Academic Search

Magnetic nanoparticle composite with a cobalt ferrite (CoFe2O4, (CF)) core and an apatite (Ap) coating was synthesized using a biomineralization process in which a modified simulated body fluid (1.5SBF) solution is the source of the calcium phosphate for the apatite formation. The core–shell structure formed after the citric acid–stabilized cobalt ferrite (CFCA) particles were incubated in the 1.5 SBF solution

I.-Ming Tang; Nateetip Krishnamra; Narattaphol Charoenphandhu; Rassmidara Hoonsawat; Weeraphat Pon-On

2011-01-01

230

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

231

Bacteriogenic manganese oxides.  

PubMed

Microorganisms control the redox cycling of manganese in the natural environment. Although the homogeneous oxidation of Mn(II) to form manganese oxide minerals is slow, solid MnO(2) is the stable form of manganese in the oxygenated portion of the biosphere. Diverse bacteria and fungi have evolved the ability to catalyze this process, producing the manganese oxides found in soils and sediments. Other bacteria have evolved to utilize MnO(2) as a terminal electron acceptor in respiration. This Account summarizes the properties of Mn oxides produced by bacteria (bacteriogenic MnO(2)) and our current thinking about the biochemical mechanisms of bacterial Mn(II) oxidation. According to X-ray absorption spectroscopy and X-ray scattering studies, the MnO(2) produced by bacteria consists of stacked hexagonal sheets of MnO(6) octahedra, but these particles are extremely small and have numerous structural defects, particularly cation vacancies. The defects provide coordination sites for binding exogenous metal ions, which can be adsorbed to a high loading. As a result, bacterial production of MnO(2) influences the bioavailability of these metals in the natural environment. Because of its high surface area and oxidizing power, bacteriogenic MnO(2) efficiently degrades biologically recalcitrant organic molecules to lower-molecular-mass compounds, spurring interest in using these properties in the bioremediation of xenobiotic organic compounds. Finally, bacteriogenic MnO(2) is reduced to soluble Mn(II) rapidly in the presence of exogenous ligands or sunlight. It can therefore help to regulate the bioavailability of Mn(II), which is known to protect organisms from superoxide radicals and is required to assemble the water-splitting complex in photosynthetic organisms. Bioinorganic chemists and microbiologists have long been interested in the biochemical mechanism of Mn(IV) oxide production. The reaction requires a two-electron oxidation of Mn(II), but genetic and biochemical evidence for several bacteria implicate multicopper oxidases (MCOs), which are only known to engage one-electron transfers from substrate to O(2). In experiments with the exosporium of a Mn(II)-oxidizing Bacillus species, we could trap the one-electron oxidation product, Mn(III), as a pyrophosphate complex in an oxygen-dependent reaction inhibited by azide, consistent with MCO catalysis. The Mn(III) pyrophosphate complex can further act as a substrate, reacting in the presence of the exosporium to produce Mn(IV) oxide. Although this process appears to be unprecedented in biology, it is reminiscent of the oxidation of Fe(II) to form Fe(2)O(3) in the ferritin iron storage protein. However, it includes a critical additional step of Mn(III) oxidation or disproportionation. We shall continue to investigate this biochemically unique process with purified enzymes. PMID:19778036

Spiro, Thomas G; Bargar, John R; Sposito, Garrison; Tebo, Bradley M

2010-01-19

232

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

233

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...

234

Action of manganese on puberty  

E-print Network

Manganese (Mn) is considered important for normal growth and reproduction. Because Mn can cross the blood brain barrier and accumulate in the hypothalamus, and because it has been suggested that infants and children are potentially more sensitive...

Lee, Bo Yeon

2007-09-17

235

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

236

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

237

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

238

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

239

Manganese metallurgy review. Part II: Manganese separation and recovery from solution  

Microsoft Academic Search

Various methods for manganese separation and recovery from solution are reviewed, which are potentially applicable to leach solutions of secondary manganese sources, particularly nickel laterite waste effluents. The main methods include solvent extraction, sulfide precipitation, ion exchange, hydroxide precipitation and oxidative precipitation. These methods are briefly compared and assessed for both purification of manganese solutions and recovery of manganese from

Wensheng Zhang; Chu Yong Cheng

2007-01-01

240

High frequency AC response, DC resistivity and magnetic studies of holmium substituted Ni-ferrite: A novel electromagnetic material  

NASA Astrophysics Data System (ADS)

Nanoparticles of holmium substituted nickel ferrites (NiHoxFe2-xO4) with x ranging from 0.0 to 0.15 have been prepared by the sol-gel auto-combustion method. Structural and morphology studies have been performed by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). XRD patterns revealed the formation of pure spinel phase ferrites without any impurity phase. Lattice parameter increases along with a decrease in crystallite size with increasing the concentration of Ho3+ in the parent nickel ferrite due to large ionic radius of Ho3+ (0.901 Å) as compared to Fe3+ (0.67 Å). SEM shows the spherical, uniformly distributed homogenous nanoparticles grown by controlled reaction parameters of the sol-gel method. Complex permittivity (?*) and complex electric modulus (M*) have been studied for the present nanoferrites in the frequency ranges of 1 MHz-1 GHz. Frequency dependent dielectric parameters (relative permittivity (?'), dielectric loss (??), dielectric loss tangent (tan ?)) decreases due to holmium substitution in nickel ferrites, showing the electrical conduction is decreasing in the nickel holmium ferrites with increase in the concentration of holmium. Complex modulus plots shows the poorly resolved semi circles and relaxation of nanoferrite is studied in the high frequency region. Also the relaxation time increases due to increase in x (0.0-0.15). DC electrical resistivity increases (107 ?-cm-1010 ?-cm) due to holmium ions substitution in nickel ferrites. Magnetic behavior was also characterized using a Vibrating Sample Magnetometer (VSM) under an applied magnetic field of 10 kOe and shows that magnetization decreases with increase in composition of holmium in nickel ferrites. High frequency behavior, low losses and very high DC electrical resistivity made the material a novel one for electromagnetic devices.

Pervaiz, Erum; Gul, I. H.

2014-01-01

241

Ferrite-guided cyclotron-resonance maser.  

PubMed

The concept of a cyclotron-resonance maser (CRM) with a ferrite loading incorporated in its waveguide is proposed. The CRM interaction occurs between the rotating electron beam and the em wave propagating along a longitudinally magnetized ferrite medium. The ferrite anisotropic permeability resembles the CRM susceptibility in many aspects, and particularly in their similar response to the axial magnetic field (the ferrite susceptibility can be regarded as a passive analog of the active CRM interaction). The ferrite loading slows down the phase velocity of the em wave and thus the axial (Weibel) mechanism of the CRM interaction dominates. The ferrite loading enables also a mechanism of spectral tunability for CRM's. The ferrite loading is proposed, therefore, as a useful ingredient for high-power CRM devices. A linear model of the combined ferrite-guided CRM interaction reveals its useful features. Future schemes may also incorporate ferrite sections functioning as isolators, gyrators, or phase shifters within the CRM device itself for selective suppression of backward waves and spurious oscillations, and for gain and efficiency enhancement. PMID:12188841

Jerby, Eli; Kesar, A; Aharony, A; Breitmeier, G

2002-06-01

242

STRAIN AGING OF AUSTENITIC HADFIELD MANGANESE STEEL  

E-print Network

STRAIN AGING OF AUSTENITIC HADFIELD MANGANESE STEEL W. S. OWEN1 { and M. GRUJICIC2 1 Department. INTRODUCTION Had®eld manganese steel, here represented by the nominal composition Fe±12Mn±1.2C wt%, is a stable. Noting that manganese decreases the activity of carbon in austenite, they speculated that the relatively

Grujicic, Mica

243

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

244

A metal-decorated nickel foam-inducing regulatable manganese dioxide nanosheet array architecture for high-performance supercapacitor applications  

NASA Astrophysics Data System (ADS)

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.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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02119j

Tang, Peng-Yi; Zhao, Yong-Qing; Wang, Yin-Mei; Xu, Cai-Ling

2013-08-01

245

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

246

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

247

Reactivity of nanoparticles; interaction between zinc and copper oxide nanoparticles and iron ions in an alkaline medium  

Microsoft Academic Search

The reactivity of zinc and copper oxide nanoparticles was investigated upon their interaction with iron oxides. It was ascertained\\u000a that, depending on the reaction conditions, nanoparticles of zinc and copper ferrites (ZnFe2O4 and CuFe2O4) or core\\/shell nanoparticles (Fe3O4\\/ZnO) are produced. Size, composition, and structure of the resulting nanoparticles were determined by transmission electron\\u000a microscopy and X-ray diffraction analysis. The average

A. Ya. Shalyapina; L. A. Polyakova; M. A. Zaporozhets; E. M. Khokhlov; S. P. Gubin

2011-01-01

248

Manganese and chronic hepatic encephalopathy  

Microsoft Academic Search

SummaryClinical observations and animal studies have raised the hypothesis that increased concentrations of manganese (Mn) in whole blood might lead to accumulation of this metal within the basal ganglia in patients with end-stage liver disease. We studied ten patients with liver failure (and ten controls) by magnetic resonance imaging (MRI) and measurement of Mn in brain tissue of three patients

D Krieger; S Krieger; L Theilmann; O Jansen; P Gass; H Lichtnecker

1995-01-01

249

Unusual metallic behavior in nanostructured cobalt ferrite at superparamagnetic regime  

NASA Astrophysics Data System (ADS)

Cobalt ferrite nanoparticles have been synthesized by coprecipitation method by varying the precipitation temperatures. The samples have been characterized by x-ray diffraction, impedance analysis, ac conductivity, dielectric, and vibrating sample magnetometer. When the average crystallite size is in the range of 2-16 nm, these compounds behave as metallic, and upon thermal activation, they become semiconducting, indicating anomalous conducting behavior. Impedance analysis reveals a metallic to semiconducting phase transition, accompanied by grain boundary effect, gradually replaced by grain contribution. Ac conductivity measurements and dielectric analysis also confirmed the transformation, when the slope changed from positive to negative as a function of temperature. Particle size independent magnetic behavior was observed in finite size limit due to site exchange of cations between tetrahedral (A) and octahedral (B) sites.

Kannan, R.; Rajagopan, S.; Arunkumar, A.; Vanidha, D.; Murugaraj, R.

2012-09-01

250

Preparation of highly anisotropic cobalt ferrite/silica microellipsoids using an external magnetic field.  

PubMed

Magnetic cobalt ferrite/silica microparticles having both an original morphology and an anisotropic nanostructure are synthesized through the use of an external magnetic field and nanoparticles characterized by a high magnetic anisotropy. The association of these two factors implies that the ESE (emulsion and solvent evaporation) sol-gel method employed here allows the preparation of silica microellipsoids containing magnetic nanoparticles aggregated in large chains. It is clearly shown that without this combination, microspheres characterized by an isotropic distribution of the magnetic nanoparticles are obtained. While the chaining of the cobalt ferrite nanoparticles inside the silica matrix is related to the increase of their magnetic dipolar interactions, the ellipsoidal shape of the microparticles may be explained by the elongation of the sol droplets in the direction of the external magnetic field during the synthesis. Because of their highly anisotropic structure, these microparticles exhibit permanent magnetic moments, which are responsible, at a larger scale, for the existence of strong magnetic dipolar interactions. Therefore, when they are dispersed in water, the microellipsoids self-assemble into large and irregular chains. These interactions can be reinforced by the use of external magnetic field, allowing the preparation of very large permanent chains. This research illustrates how nanostructured particles exhibiting complex architectures can be elaborated through simple, fast, and low-cost methods, such as the use of external fields in combination with soft chemistry. PMID:25029515

Abramson, Sébastien; Dupuis, Vincent; Neveu, Sophie; Beaunier, Patricia; Montero, David

2014-08-01

251

The nature of acicular ferrite in HSLA steel weld metals  

Microsoft Academic Search

In this paper, the nature of the fine interlocking acicular ferrite microstructure in HSLA steel weld metals is investigated. The results strongly suggest the acicular ferrite is comprised of intragranularly nucleated Widmanstätten ferrite. Further, it is shown that the active nucleation sites for this ferritic product are weld metal inclusions. Sympathetic nucleation then takes place which leads eventually to the

R. A. Ricks; P. R. Howell; G. S. Barritte

1982-01-01

252

Application of Ferrite to Electromagnetic Wave Absorber and its Characteristics  

Microsoft Academic Search

An electromagnetic wave absorber utilizing ferrite or rubber ferrite composed of ferrite powder and rubber is described. In our investigation, the existence of a matching frequency fm and a matching thickness tm has been found. The terms fm and tm mean that the ferrite which is backed with a conducting plate can be a perfect absorber only under the conditions

YOSHIYUKI NAITO; KUNIHIRO SUETAKE

1971-01-01

253

Investigation of the thermal stability of Mn ferrite particles synthesized by a modified co-precipitation method  

NASA Astrophysics Data System (ADS)

Manganese ferrite particles with spinel structure were synthesized by a modified co-precipitation method, and then the thermal stability on their structural and magnetic properties was investigated by thermal annealing at different gas ambients. Experimental results showed that decomposition of metal oxides occurred when Mn ferrite particles with spinel structure were annealed under air ambient, while samples annealed in vacuum or argon remained in the spinel structural form. The highest saturation magnetization value of 58 emu/g was obtained when the sample was annealed at 400°C in argon. The result showed that the thermal stability of MnFe2O4 was better under Ar ambient conditions or in vacuum.

Dong, ChunHui; Wang, GaoXue; Shi, Lei; Guo, DangWei; Jiang, ChangJun; Xue, DeSheng

2013-03-01

254

Structure and Conductivity of Thermally Grown Scales on Ferritic Fe-Cr-Mn Steel for SOFC Interconnect Applications  

SciTech Connect

With the development of solid oxide fuel cells (SOFC) that operate in the intermediate temperature range of 650-800 degrees C, ferritic stainless steels have become promising candidate materials for interconnects in SOFC stacks. The SOFC interconnect requires that the alloy possess not only excellent surface stability, but also high electrical conductivity through the oxide scale that forms at elevated temperatures and contributes to the alloy’s surface stability. It appears that ferritic Fe-Cr-Mn alloys may be potential candidates due to the formation of an electrically conductive scale containing (Mn,Cr)3O4 spinel. To improve the understanding of scale growth on manganese-containing ferritic stainless steels and evaluate their suitability for use in SOFC interconnects, the oxidation behavior (i.e., growth kinetics, composition, structure, and electrical conductivity of the oxide scale) exhibited in a commercially available Fe-Cr-Mn steel developed specifically for SOFC applications was investigated. The results are reported and compared with those of conventional ferritic stainless steel compositions.

Yang, Z Gary; Hardy, John S.; Walker, Matthew S.; Xia, Gordon; Simner, Steve P.; Stevenson, Jeffry W.

2004-10-01

255

Delta ferrite in the weld metal of reduced activation ferritic martensitic steel  

NASA Astrophysics Data System (ADS)

Formation of delta(?)-ferrite in the weld metal, during autogenous bead-on-plate welding of Reduced Activation Ferritic Martensitic (RAFM) steel using Gas Tungsten Arc Welding (GTAW) process, has been studied. Composition of the alloy is such that delta-ferrite is not expected in the alloy; but examination of the weld metal revealed presence of delta-ferrite in the weld metal. Volume fraction of delta-ferrite is found to be higher in the weld interface than in the rest of the fusion zone. Decrease in the volume fraction of delta-ferrite, with an increase in preheat temperature or with an increase in heat input, is observed. Results indicate that the cooling rate experienced during welding affects the volume fraction of delta-ferrite retained in the weld metal and variation in the delta-ferrite content with cooling rate is explained with variation in the time that the weld metal spends in various temperature regimes in which delta-ferrite is stable for the alloy during its cooling from the liquid metal to the ambient temperature. This manuscript will discuss the effect of welding parameters on formation of delta-ferrite and its retention in the weld metal of RAFM steel.

Sam, Shiju; Das, C. R.; Ramasubbu, V.; Albert, S. K.; Bhaduri, A. K.; Jayakumar, T.; Rajendra Kumar, E.

2014-12-01

256

Mechanical and thermomechanical properties of radiation modified poly(ethylene-octene)/Ni-Zn ferrite nanocomposites  

NASA Astrophysics Data System (ADS)

Poly(ethylene-1-octene) copolymer (POE) composites filled with nickel-zinc ferrite nanoparticles have been modified by exposure to an electron beam at doses up to 500 kGy. The influence of radiation dose and ferrite content on mechanical properties has been investigated. Thermomechanical properties - thermorelaxation stresses formed in thermal heating and thermo residual stresses resulting in the process of full setting and cooling of materials have been investigated for radiation cross-linked oriented (extended up to 100%) composite samples. Increase of concentration of ferrite particles and increase of radiation dose affects a notable increase of elastic modulus and reduces the deformability in comparison to entire elastomer. Improvement of thermomechanical properties especially at low irradiation doses (100-150 kGy) have been detected for composites with increase of ferrite filler content up to 5 wt. %. It was found that gel content of POE increased up to 85% for pristine POE material with increase of irradiation dose up to 500 kGy due to the formation of cross-linked structure, increase of filler concentration up to 5 wt. % affect reduction in gel fraction due to uniform dispersion in amorphous (ethylene and substituted with hexyl branches) POE phases.

Reinholds, I.; Kalkis, V.; Zicans, J.; Merijs Meri, R.; Bockovs, I.; Grigalovica, A.; Muizzemnieks, G.

2013-12-01

257

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

2014-05-14

258

Dynamic optical probing of the magnetic anisotropy of nickelferrite nanoparticles  

Microsoft Academic Search

Field dependence of dynamic magneto-orientational birefringence in a ferrocolloid based on the nickel-ferrite nanoparticles is examined. The nanoparticles are electrostatically stabilized and suspended in glycerin at low-volume fractions Phi<=0.75%. The colloids are tested under crossed magnetic fields: an alternating weak (probing) and a constant strong (bias) one. By comparison to a theoretical model of the birefringence relaxation, an evaluation of

Yu. L. Raikher; V. I. Stepanov; J. Depeyrot; M. H. Sousa; F. A. Tourinho; E. Hasmonay; R. Perzynski

2004-01-01

259

Chemical and microbiological studies of sulfide?mediated manganese reduction  

Microsoft Academic Search

Laboratory studies of manganese reduction by naturally occurring reduced inorganic compounds were undertaken, both to study further possible in situ mechanisms of manganese reduction and to examine how manganese redox reactions might be coupled to other biogeochemical processes. Chemical manganese reduction by sulfide (in the presence of excess manganese oxide) was found to be rapid and complete, with all sulfide

David J. Burdige; Kenneth H. Nealson

1986-01-01

260

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

261

Multicycle testing of zinc ferrite  

SciTech Connect

Zinc ferrite is a leading regenerable sorbent candidate for high- temperature desulfurization of coal gasifier gases. 3/16'' extrudates of a particular zinc ferrite (T-2465) were subjected to two multicycle tests (Test 1 and Test 2) in a high pressure high-temperature bench-scale fixed-bed reactor. In both tests, simulated KRW gasifier gases were used for sulfidation. In Test 1, the sorbent was mixed with 5 weight percent coal char fines elutriated from the KRW gasifier prior to the testing. The simulated gas for this test contained 15 volume percent steam. In Test 2, the sorbent was tested without fines but in the presence of a simulated gas containing only 5 volume percent steam. Over 15 cycles during Test 1 and 5 cycles during Test 2, the sorbent consistently reduced the hydrogen sulfide (H/sub 2/S) concentration to less than 5 ppmv and exhibited no downward trend in sulfur adsorption capacity. However, the sorbent extrudates underwent considerable reduction in strength during both tests. During Test 1, crush strength of the sorbent declined from 4.1 lb/mm to 1.3 lb/mm and some decrepitation occurred. Decrepitation and strength reduction were much more severe during Test 2 as only 30% of the sorbent extrudates remained intact after 5 cycles. Carbon formation followed by sorbent-carbon interaction is believed to be the primary cause of the strength reduction. 5 refs., 9 figs., 15 tabs.

Gangwal, S.K.; Harkins, S.M.; Stogner, J.M.; Woods, M.C.

1988-10-01

262

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

263

Removal of actinides from waste solutions by ferrite treatment. [Adsorption onto the ferrite surface or chemical incorporation into ferrite molecules  

SciTech Connect

Ferrite treatment was found to be effective in removing actinides from Rocky Flats process waste solutions. With one ferrite treatment, plutonium concentrations were consistently reduced from around 10/sup -4/ g/l to between 10/sup -7/ and 10/sup -8/ g/l. Three to four grams of solids were produced per liter of solution treated as compared to 15.7 g/l observed for the flocculant precipitation technique now in use at Rocky Flats. Less cement was required for the immobilization of ferrite solids resulting in further reductions in waste generation. The success of ferrite treatment in laboratory studies has prompted serious consideration of this technique for implementation in plant operations.

Boyd, T.E.; Kochen, R.L.

1982-01-01

264

Removal of actinides from waste solutions by ferrite treatment. [Adsorption onto the ferrite surface or chemical incorporation into ferrite molecules  

SciTech Connect

Ferrite treatment was found to be effective in removing actinides from Rocky Flats process waste solutions. With one ferrite treatment, plutonium concentrations were consistently reduced from around 10/sup -4/ g/l to between 10/sup -7/ and 10/sup -8/ g/l. Three to four grams of solids were produced per liter of solution treated as compared to 15.7 g/l observed for the flocculant precipitation technique now in use at Rocky Flats. Less cement was required for the immobilization of ferrite solids resulting in further reductions in waste generation. The success of ferrite treatment in laboratory studies has prompted serious consideration of this technique for implementation in plant operations.

Boyd, T.E.; Kochen, R.L.

1983-01-01

265

Spectroscopic characterization of manganese minerals  

NASA Astrophysics Data System (ADS)

Manganese minerals ardenite, alleghanyite and leucopoenicite originated from Madhya Pradesh, India, Nagano prefecture Japan, Sussex Country and Parker Shaft Franklin, Sussex Country, New Jersey respectively are used in the present work. In these minerals manganese is the major constituent and iron if present is in traces only. An EPR study of on all of the above samples confirms the presence of Mn(II) with g around 2.0. Optical absorption spectrum of the mineral alleghanyite indicates that Mn(II) is present in two different octahedral sites and in leucophoenicite Mn(II) is also in octahedral geometry. Ardenite mineral gives only a few Mn(II) bands. NIR results of the minerals ardenite, leucophoenicite and alleghanyite are due to hydroxyl and silicate anions which confirming the formulae of the minerals.

Lakshmi Reddy, S.; Padma Suvarna, K.; Udayabhaska Reddy, G.; Endo, Tamio; Frost, R. L.

2014-01-01

266

Raman study of ionic water-based copper and zinc ferrite magnetic fluids  

NASA Astrophysics Data System (ADS)

Raman spectroscopy is used to investigate the OH-bending and OH-stretching modes of chemisorbed OH-groups in copper-ferrite and zinc-ferrite water-based magnetic fluid samples. Room-temperature Raman spectra were taken from diluted magnetic fluid samples and compared with the spectrum taken from liquid water. The suppression of the symmetric OH-stretching Raman modes from the ionic magnetic fluid sample spectra is discussed in terms of the replacement of a hydrogen atom from the water molecule by the nanoparticle surface. Moreover, changes on the area ratio between hydrogen bonded and nonhydrogen bonded OH-Raman peaks in the ionic magnetic fluid samples, as compared to the OH-Raman peaks from liquid water, are discussed in terms of changes on the hydrogen bond strength.

Morais, P. C.; da Silva, S. W.; Soler, M. A. G.; Sousa, M. H.; Tourinho, F. A.

1999-07-01

267

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

268

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

269

Iron and manganese in lakes  

Microsoft Academic Search

The role of redox processes in determining the chemistry of iron and manganese is considered systematically. Both metals have soluble reduced forms and insoluble oxyhydroxides which are readily interconverted in the vicinity of a redox boundary. Although the oxyhydroxides are dominant in well-oxygenated waters, measureable concentrations of Fe(II) and Mn(II) can be observed, especially where photochemical reduction occurs. Differences in

William Davison

1993-01-01

270

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Cobalt lithium manganese nickel oxide. 721.10201...Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical...chemical substance identified as cobalt lithium manganese nickel oxide (PMN...

2013-07-01

271

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Cobalt lithium manganese nickel oxide. 721.10201...Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical...chemical substance identified as cobalt lithium manganese nickel oxide (PMN...

2012-07-01

272

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2013-07-01

273

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

...2014-07-01 false Barium calcium manganese strontium oxide. 721.10011 Section...Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance...substance identified as barium calcium manganese strontium oxide (PMN...

2014-07-01

274

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2012-07-01

275

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

...2014-07-01 2014-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2014-07-01

276

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.  

...2014-07-01 false Cobalt lithium manganese nickel oxide. 721.10201 Section...Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance...substance identified as cobalt lithium manganese nickel oxide (PMN...

2014-07-01

277

Heterogeneous clay-manganese(II) oxidation catalyst  

Microsoft Academic Search

A manganese(II)-Schiff base complex has been heterogenized by its intercalation into clay minerals. The incorporation of the homogeneous manganese(II) complexes in the interlayer space of aluminosilicate mineral is accomplished by a cation exchange process. The obtained clay-manganese(II) composite has been studied by chemical analysis, X-ray diffraction and FT-IR spectroscopy. The new catalytic material has been evaluated as oxidation catalyst. Our

D Gournis; M Louloudi; M. A Karakassides; C Kolokytha; K Mitopoulou; N Hadjiliadis

2002-01-01

278

Comment on “Methylcyclopentadienyl Manganese Tricarbonyl as an Antiknock: Composition and Fate of Manganese Exhaust Products”  

Microsoft Academic Search

In an article published in the August 1975, Journal of the Air Pollution Control Association entitled “Methylcyclopentadienyl Manganese Tricarbonyl as an Antiknock: Composition and Pate of Manganese Exhaust Products,” the authors conclude that, “… use of MMT in gasoline will result in no public health hazards, because of the low toxicity of manganese and because of the very low concentration

Edward J. Calabrese; Alfred Sorensen

1975-01-01

279

Influence of Dietary Manganese on the Pharmacokinetics of Inhaled Manganese Sulfate in Male CD Rats  

Microsoft Academic Search

Concerns exist as to whether individuals with relative manga- nese deficiency or excess may be at increased risk for manganese toxicity following inhalation exposure. The objective of this study was to determine whether manganese body burden influences the pharmacokinetics of inhaled manganese sulfate (MnSO4). Postna- tal day (PND) 10 rats were placed on either a low (2 ppm), sufficient (10

David C. Dorman; Melanie F. Struve; R. Arden James; Brian E. McManus; Marianne W. Marshall; Brian A. Wong

2001-01-01

280

Bacterial Manganese Reduction and Growth with Manganese Oxide as the Sole Electron Acceptor  

Microsoft Academic Search

Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium, Alteromonas putrefaciens MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest

Charles R. Myers; Kenneth H. Nealson

1988-01-01

281

MO.Fe2O3 nanoparticles for self-controlled magnetic hyperthermia  

Microsoft Academic Search

Using a model Hamiltonian and the Green's function technique for the Zn doped Mn-ferrite, Mn1-xZnxO.Fe2O3, and the Gd doped Zn-ferrite, ZnGdxFe(2-x)O4, nanoparticles of different compositions x were studied. The phase transition temperature, TC, and the coercive field, Hc, for different samples dependent upon composition, particle size, and shape were investigated. An attempt was made to enhance or to lower the

A. T. Apostolov; I. N. Apostolova; J. M. Wesselinowa

2011-01-01

282

ZnFe 2O 4 nanoparticles for ferrofluids: A combined XANES and XRD study  

Microsoft Academic Search

A soft-chemistry method is used to synthesize zinc ferrite nanoparticles to prepare a magnetic fluid. We investigate here their internal structure by X-ray Absorption Near Edge Spectroscopy (XANES) and X-Ray Diffraction (XRD). A cross analysis of XANES and Rietveld refinement of XRD spectra shows non-equilibrium site occupancy with respect to bulk zinc ferrite, suggesting a cation redistribution that enhances the

J. A. Gomes; G. M. Azevedo; J. Depeyrot; J. Mestnik-Filho; G. J. da Silva; F. A. Tourinho; R. Perzynski

2011-01-01

283

Role of manganese: Are welders at risk?.  

E-print Network

??Serious concerns exist among welders and occupational health investigators on the possible association between exposure to manganese via welding fumes and neurological effects. One suggestion… (more)

Nawrocki, R.P.

2012-01-01

284

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

285

Battles with Iron: Manganese in Oxidative Stress Protection*  

PubMed Central

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.

2012-01-01

286

REGULAR ARTICLE Interaction of nickel and manganese in accumulation  

E-print Network

REGULAR ARTICLE Interaction of nickel and manganese in accumulation and localization in leaves . Hyperaccumulator. Manganese localization . Nickel localization . Phytoremediation . trichomes Introduction More

Sparks, Donald L.

287

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

288

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

289

Ferromagnetic resonance in ferrite nanoparticles with uniaxial surface anisotropy  

Microsoft Academic Search

Magnetization oscillations in a single-domain spherical ferromagnetic particle with uniaxial surface and bulk anisotropies are studied. In a linear approximation we consider a weakly nonuniform precession mode and derive the dispersion relationships for the cases of the applied field either parallel or normal to the particle easy axis. It is shown that in both situations the surface can produce a

V. P. Shilov; J.-C. Bacri; F. Gazeau; F. Gendron; R. Perzynski; Yu. L. Raikher

1999-01-01

290

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

291

Manganese Neurotoxicity: An Update of Pathophysiologic Mechanisms  

Microsoft Academic Search

The central nervous system, and the basal ganglia in particular, is an important target in manganese neurotoxicity, a disorder producing neurological symptoms similar to that of Parkinson's disease. Increasing evidence suggests that astrocytes are a site of early dysfunction and damage; chronic exposure to manganese leads to selective dopaminergic dysfunction, neuronal loss, and gliosis in basal ganglia structures together with

Louise Normandin; Alan S. Hazell

2002-01-01

292

Globally sustainable manganese metal production and use  

Microsoft Academic Search

The “cradle to grave” concept of managing chemicals and wastes has been a descriptive analogy of proper environmental stewardship since the 1970s. The concept incorporates environmentally sustainable product choices—such as metal alloys utilized steel products which civilization is dependent upon. Manganese consumption is related to the increasing production of raw steel and upgrading ferroalloys. Nonferrous applications of manganese include production

Karen Hagelstein

2009-01-01

293

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

294

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), ˜7nm 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±50nm and saturation magnetizations of 28emu /g, exceeding commercially available polymer-coated beads of micron size having a weaker saturation magnetization (˜12emu/g).

Nishibiraki, H.; Kuroda, C. S.; Maeda, M.; Matsushita, N.; Abe, M.; Handa, H.

2005-05-01

295

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

296

The structural changes of Y2O3 in ferritic ODS alloys during milling  

NASA Astrophysics Data System (ADS)

Oxide dispersion strengthened (ODS) ferritic steels are usually fabricated via mechanical alloying and subsequent consolidation via hot extrusion or hot isostatic pressing. During the individual process steps, a complex evolution of the nanoparticle structure is taking place. Powders with different Y2O3 contents were milled and examined by means of X-ray diffraction (XRD) and atom probe tomography (APT). It has been observed that the Y2O3 is fragmented and becomes partially amorphous upon milling due to the grain refinement of Y2O3 during the milling process. There was no compelling evidence for Y2O3 dissociation and dissolution into the steel matrix.

Hilger, I.; Tegel, M.; Gorley, M. J.; Grant, P. S.; Weißgärber, T.; Kieback, B.

2014-04-01

297

Manganese regulates expression of manganese peroxide by Phanerochaete chrysosporium  

SciTech Connect

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.

Brown, J.A.; Glenn, J.K.; Gold, M.H. (Oregon Graduate Institute of Science and Technology, Beaverton (USA))

1990-06-01

298

Surfactant-controlled morphology and magnetic property of manganese ferrite nanocrystal contrast agent  

NASA Astrophysics Data System (ADS)

MnFe2O4 nanocrystals (NCs) coated with three different surfactants (oleic acid, oleylamine or 1,2-hexadecanediol) and their mixtures, with sizes in range 6-12 nm, were synthesized by high-temperature decomposition of organometallic precursors. The effects of morphology and surface chemistry of MnFe2O4 NCs on the magnetic properties were systematically investigated by comparing their saturation magnetization values and their capability to improve the negative contrast for magnetic resonance imaging (MRI) after converting the hydrophobic NCs to hydrophilic ones by a ligand exchange protocol. An important finding is that the magnetization values and proton relaxivity rates of MnFe2O4 NCs are strongly dependent on the size and surface state of the particles that covalently bonded with different hydrophobic ligands before ligand exchange. In particular, monodisperse cubic MnFe2O4 NCs could be obtained when oleylamine and 1,2-hexadecanediol were used as mixed stabilizers, and showed excellent morphology and magnetic properties. Furthermore, the low cytotoxicity and good cell uptake MR imaging of the dopamine capped MnFe2O4 NCs make them promising candidates for use as bio-imaging probes.

Hu, He; Tian, Zhi-qing; Liang, Jie; Yang, Hong; Dai, An-tao; An, Lu; Wu, Hui-xia; Yang, Shi-ping

2011-02-01

299

Synthesis and characterization of carbon nanotubes decorated with manganese–zinc ferrite nanospheres  

Microsoft Academic Search

Mn1?xZnxFe2O4 nanospheres were self-assembled alongside the multi-walled carbon nanotubes (MWCNTs) via solvothermal method. The shape, structure, and size of the as-synthesized sample were characterized by X-ray diffraction pattern (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results shown that a large number of the high purity Mn1?xZnxFe2O4 nanocrystallites were decorated on the sidewalls

Qi Zhang; Meifang Zhu; Qinghong Zhang; Yaogang Li; Hongzhi Wang

2009-01-01

300

Effect of alloying on microstructure and precipitate evolution in ferritic weld metal  

NASA Astrophysics Data System (ADS)

The effect of alloying on the microstructure of ferritic weld metal produced with an self-shielded flux cored arc welding process (FCAW-S) has been studied. The welding electrode has a flux core that is intentionally alloyed with strong deoxidizers and denitriding elements such as aluminum, titanium and zirconium in addition to austenite formers such as manganese and nickel. This results in formation of microstructure consisting of carbide free bainite, retained austenite and twinned martensite. The work focuses on characterization of the microstructures and the precipitates formed during solidification and the allotropic phase transformation of the weld metal. Aluminum, manganese and nickel have significant solubility in iron while aluminum, titanium and zirconium have very strong affinity for nitrogen and oxygen. The effect of these alloying elements on the phase transformation and precipitation of oxides and nitrides have been studied with various characterization techniques. In-situ X-ray synchrotron diffraction has been used to characterize the solidification path and the effect of heating and cooling rates on microstructure evolution. Scanning Transmission Electron Microscopy (STEM) in conjunction with Energy Dispersive Spectroscopy (EDS) and Electron energy loss spectroscopy (EELS) was used to study the effect of micro-alloying additions on inclusion evolution. The formation of core-shell structure of oxide/nitride is identified as being key to improvement in toughness of the weld metal. Electron Back Scattered Diffraction (EBSD) in combination with Orientation Imaging Microscopy (OIM) and Transmission electron microscopy (TEM) has been employed to study the effect of alloying on austenite to ferrite transformation modes. The prevention of twinned martensite has been identified to be key to improving ductility for achieving high strength weld metal.

Narayanan, Badri Kannan

301

The Structural Stability of Manganese Oxide Electrodes for Lithium Batteries  

Microsoft Academic Search

Manganese oxides are of interest as insertion electrodes for rechargeable 3 V and 4 V lithium batteries. During discharge, lithium ions are inserted into the manganese oxide host structure with a concomitant reduction of the manganese ions; the reverse process occurs on charge. The cycle life of these batteries is critically dependent on the ability of the manganese oxide structure

Michael M. Thackeray

1997-01-01

302

SYNTHESIS OF NANOSIZED ZINC FERRITES IN RF THERMAL PLASMA REACTOR  

E-print Network

SYNTHESIS OF NANOSIZED ZINC FERRITES IN RF THERMAL PLASMA REACTOR L. Gál1 , I. Mohai1 , Z. Károly1 zinc ferrites was studied under thermal plasma conditions. Mixture of oxide powders and ethanolFe2O4; Thermal plasma; XRD; SEM; TEM; Saturation magnetization 1. Introduction Ferrite spinels

Gubicza, Jenõ

303

Improved magnetostrictive properties of Co-Mn ferrites for automobile torque sensor applications  

NASA Astrophysics Data System (ADS)

Strain derivative of local anisotropy, which depends on the magnetostriction, is the figure of merit for the magnetic materials used in automobile torque sensor applications. In order to improve the strain derivative, a series of samples with chemical formulae CoMnxFe2-xO4 (x=0.00-0.60) was prepared by a conventional ceramic technique. X-ray diffraction patterns of the samples confirm cubic spinel crystal structures. The magnetic properties, such as saturation magnetization and coercivity, were measured and the Curie temperature was estimated. Magnetostrictive properties were studied by the tensile strain gauge method. Manganese substituted cobalt ferrites have shown improved strain derivative values as compared to the pure cobalt ferrite. The strain derivative has been observed to increase for larger Mn substituent concentrations in CoMnxFe2-xO4. This behavior has been ascribed to the net decreased anisotropic contribution due to the increased presence of Mn3+ ions in B-sites and a corresponding migration of Co2+ ions to A-sites, and also to the microstructural grain size of the samples. The coercivity and magnetostriction measurements are in support of the strain derivative variations. The results are discussed on the basis of cationic site occupancies, variations in grain size and reduced anisotropy of the system.

Rao, G. S. N.; Caltun, O. F.; Rao, K. H.; Subba Rao, P. S. V.; Parvatheeswara Rao, B.

2013-09-01

304

Manganese metallurgy review. Part I: Leaching of ores\\/secondary materials and recovery of electrolytic\\/chemical manganese dioxide  

Microsoft Academic Search

The world rapidly growing demand for manganese has made it increasingly important to develop processes for economical recovery of manganese from low grade manganese ores and other secondary sources. Part I of this review outlines metallurgical processes for manganese production from various resources, particularly focusing on recent developments in direct hydrometallurgical leaching and recovery processes to identify potential sources of

Wensheng Zhang; Chu Yong Cheng

2007-01-01

305

Isotopic evidence for organic matter oxidation by manganese reduction in the formation of stratiform manganese carbonate ore  

Microsoft Academic Search

Unlike other marine-sedimentary manganese ore deposits, which are largely composed of manganese oxides, the primary ore at Molango (Hidalgo State, Mexico) is exclusively manganese carbonate (rhodochrosite, Mn-calcite, kutnahorite). Stable isotope studies of the carbonates from Molango provide critical new information relevant to the controversy over syngenetic and diagenetic models of stratiform manganese deposit formation. Negative 13 C values for carbonates

Patrick M. Okita; J. Barry Maynard; Elliott C. Spiker; Eric R. Force

1988-01-01

306

Regulation of Superoxide Dismutase Activity by Dietary Manganese1  

Microsoft Academic Search

The activity of Superoxide dismutase in rats, mice and chickens fed purified diets containing various levels of manganese has been studied. In liver of manganese-deficient mice, the activity of CNMnsensitive manganese Superoxide dismutase was only 17% of that found in control mice. In the brain, Superoxide dismutase activity was reduced by 50% in the manganese-deficient mice. In manganese-deficient rats, activity

GUGLIELMO DEROSA; CARL L. KEEN

2010-01-01

307

[Manganese in atherogenesis: detection, origin, and role].  

PubMed

The role of transition metal ions in atherogenesis is controversial; they can participate in the hydroxyl radical generation and catalyze the reactive oxygen species neutralization reaction as cofactors of antioxidant enzymes. Using EPR spectroscopy, we revealed that 70% of the samples of aorta with atherosclerotic lesions possessed superoxide dismutase activity, 100% of the samples initiated Fenton reaction and demonstrated the presence of manganese paramagnetic centers. The sodA gene encoding manganese-dependent bacterial superoxide dismutase was not found in the samples of atherosclerotic plaques by PCR using degenerate primers. The data obtained indicates the perspectives of manganese analysis as a marker element in the express diagnostics of atherosclerosis. PMID:22856134

Lozhkin, A P; Biktagirov, T B; Abdul'ianov, V A; Gorshkov, O V; Timonina, E V; Mamin, G V; Orlinski?, S B; Silkin, N I; Chernov, V M; Kha?rullin, R N; Salakhov, M Kh; Il'inskaia, O N

2012-01-01

308

Thermal processing of ferritic 5Mn steel for toughness at cryogenic temperatures  

NASA Astrophysics Data System (ADS)

It is shown that a thermal treatment which combines grain refinement with an intercritical temper (the 2 BT treatment) may be used to achieve a promising combination of strength and toughness in a nickel-free ferritic steel of nominal composition Fe-5Mn-0.2Mo-0.04C at temperatures as low as -196 °C. The properties achieved are attributed to a symbiotic influence between the grain refinement treatment and the introduction of thermally stable retained austenite during intercritical tempering, a conclusion supported by a comparison of the results to those obtained with simpler heat treatments. The influence of carbon, manganese, and nickel additions to the base compositions are studied. An increase in carbon content above 0.04 wt pct causes a deterioration in toughness, as does an increase in manganese to 8 wt pct. An addition of 1 to 3 wt pct nickel is beneficial giving an increase in alloy strength at -196 °C without loss of toughness.

Niikura, M.; Morris, J. W.

1980-09-01

309

Chronic manganese poisoning: A neuropathological study with determination of manganese distribution in the brain  

Microsoft Academic Search

An autopsy case of a 52-year-old man suffering from chronic manganese poisoning (CMP) is reported with determination of the manganese distribution in the brain. The patient had been working in a manganese ore crushing plant since 1965. In 1967 he began to complain of difficulties in walking and diminished libido. Later, he developed various neuro-psychiatric symptoms including euphoria, emotional incontinence,

M. Yamada; S. Ohno; I. Okayasu; R. Okeda; S. Hatakeyama; H. Watanabe; K. Ushio; H. Tsukagoshi

1986-01-01

310

A preliminary ferritic-martensitic stainless steel constitution diagram  

SciTech Connect

This paper describes preliminary research to develop a constitution diagram that will more accurately predict the microstructure of ferritic and martensitic stainless steel weld deposits. A button melting technique was used to produce a wide range of compositions using mixtures of conventional ferritic and martensitic stainless steels, including types 403, 409, 410, 430, 439 and 444. These samples were prepared metallographically, and the vol-% ferrite and martensite was determined quantitatively. In addition, the hardness and ferrite number (FN) were measured. Using this data, a preliminary constitution diagram is proposed that provides a more accurate method for predicting the microstructures of arc welds in ferritic and martensitic stainless steels.

Balmforth, M.C.; Lippold, J.C. [Ohio State Univ., Columbus, OH (United States). Welding and Joining Metallurgy Group

1998-01-01

311

Magnetic and structural properties of nano sized Dy-doped cobalt ferrite synthesized by co-precipitation  

NASA Astrophysics Data System (ADS)

Regarding the various applications of cobalt ferrite as a magnetic ceramic in various scientific and industrial categories, it is essential to modify and optimize its microstructural and magnetic features. Chemical composition (doped elements and their quantities) is a determining factor which has been studied in this research. For this purpose, cobalt-dysprosium ferrite ceramic nanoparticles with the chemical formula Co1-xDyxFe2O4 (x=0, 0.01, 0.03, 0.05, 0.1) were synthesized by the co-precipitation chemical method and then analyzed from the structural and magnetic perspectives. The desirable spinel phase formation was confirmed via x-ray diffractometry, and the other crystallographic parameters and cation distribution were calculated. The microscopic image of the samples showed 15 nm particles. The type and strength of the interionic bonds were determined by infrared spectroscopy. The hysteresis loop of the material was affected noticeably by doped elements as the room temperature saturation magnetization was decreased, but the residual magnetization and coercivity of ferrite were promoted by 50 and 150% after adding dysprosium, respectively. The maximum anisotropy constant, which is equal to 19.1 erg/g for undoped cobalt ferrite, was increased to 45.2 erg/g by doping 0.05 dysprosium. It is worth mentioning that introducing dopants into the lattice led to a great decrease in Curie temperature.

Karimi, Z.; Mohammadifar, Y.; Shokrollahi, H.; Asl, Sh. Khameneh; Yousefi, Gh.; Karimi, L.

2014-06-01

312

Anti-microbial active composite nanoparticles with magnetic core and photocatalytic shell: TiO2-NiFe2O4 biomaterial system.  

PubMed

Reverse micelle and chemical hydrolysis techniques have been successfully combined to synthesize composite nanoparticles consisting of a photocatalytic shell of titania and a magnetic core of nickel ferrite. The nature of titania shell, i.e. anatase or brookite, depends on the TiO2 and NiFe2O4 molar ratio. The work presented here describes the photocatalytic and anti-microbial activity of the composite nanoparticles together with the magnetic characteristics of the nickel ferrite core. The TiO2-coated NiFe2O4 nanoparticles retain the magnetic characteristics of uncoated nanocrystalline nickel ferrites (superparamagnetism; absence of hysteresis, remanence and coercivity at 300 K) encouraging their application as removable anti-microbial photocatalyst nanoparticles that can be extracted from the sprayed surface (human body or environment) after exposure. PMID:16701850

Rana, S; Rawat, J; Misra, R D K

2005-11-01

313

21 CFR 184.1452 - Manganese gluconate.  

...by reacting manganese carbonate with gluconic acid in aqueous medium and then crystallizing the product. (b) The ingredient...accordance with section 412(g) of the Federal Food, Drug, and Cosmetic Act (the act) or with regulations promulgated under...

2014-04-01

314

21 CFR 184.1452 - Manganese gluconate.  

Code of Federal Regulations, 2012 CFR

...by reacting manganese carbonate with gluconic acid in aqueous medium and then crystallizing the product. (b) The ingredient...accordance with section 412(g) of the Federal Food, Drug, and Cosmetic Act (the act) or with regulations promulgated under...

2012-04-01

315

21 CFR 184.1452 - Manganese gluconate.  

Code of Federal Regulations, 2011 CFR

...by reacting manganese carbonate with gluconic acid in aqueous medium and then crystallizing the product. (b) The ingredient...accordance with section 412(g) of the Federal Food, Drug, and Cosmetic Act (the act) or with regulations promulgated under...

2011-04-01

316

21 CFR 184.1452 - Manganese gluconate.  

Code of Federal Regulations, 2013 CFR

...by reacting manganese carbonate with gluconic acid in aqueous medium and then crystallizing the product. (b) The ingredient...accordance with section 412(g) of the Federal Food, Drug, and Cosmetic Act (the act) or with regulations promulgated under...

2013-04-01

317

21 CFR 184.1452 - Manganese gluconate.  

Code of Federal Regulations, 2010 CFR

...by reacting manganese carbonate with gluconic acid in aqueous medium and then crystallizing the product. (b) The ingredient...accordance with section 412(g) of the Federal Food, Drug, and Cosmetic Act (the act) or with regulations promulgated under...

2010-04-01

318

21 CFR 184.1461 - Manganese sulfate.  

...manganese dioxide in sulfuric acid, and the roasting of pyrolusite (MnO2 ) ore with solid ferrous sulfate and coal, followed by leaching and crystallization. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed....

2014-04-01

319

21 CFR 184.1461 - Manganese sulfate.  

Code of Federal Regulations, 2013 CFR

...manganese dioxide in sulfuric acid, and the roasting of pyrolusite (MnO2 ) ore with solid ferrous sulfate and coal, followed by leaching and crystallization. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed....

2013-04-01

320

Electrochemical lithium intercalation in nanosized manganese oxides  

Microsoft Academic Search

X-ray amorphous manganese oxides were prepared by reduction of sodium permanganate by lithium iodide in aqueous medium (MnOx-I) and by decomposition of manganese carbonate at moderate temperature (MnOx-C). TEM showed that these materials are not amorphous, but nanostructured, with a prominent spinel substructure in MnOx-C. These materials intercalate lithium with capacities up to 200mAh\\/g at first cycle (potential window 1.8–4.3V)

Pierre Strobel; Céline Darie; F. Thiéry; A. Ibarra-Palos; Maria Bacia; Olivier Proux; Jean-Bruno Soupart

2006-01-01

321

Manganese induced modifications in yttria stabilized zirconia  

NASA Astrophysics Data System (ADS)

We have investigated the role of manganese oxide on the crystallographic and morphological modifications of cubic 8 mol. % yttria stabilized zirconia (YSZ). X-ray diffraction studies indicate that manganese dissolution leads to partial transformation of cubic YSZ into the tetragonal polymorph along with contraction of the unit cell. Evolution of an undulated surface with 2-15 nm roughness has been observed using electron and atomic force microscopies.

Mahapatra, Manoj K.; Singh, Prabhakar; Misture, Scott T.

2012-09-01

322

Manganese recycling in the United States in 1998  

USGS Publications Warehouse

This report describes the flow and processing of manganese within the U.S. economy in 1998 with emphasis on the extent to which manganese is recycled. Manganese was used mostly as an alloying agent in alloys in which it was a minor component. Manganese was recycled mostly within scrap of iron and steel. A small amount was recycled within aluminum used beverage cans. Very little manganese was recycled from materials being recovered specifically for their manganese content. For the United States in 1998, 218,000 metric tons of manganese was estimated to have been recycled from old scrap, of which 96% was from iron and steel scrap. Efficiency of recycling was estimated as 53% and recycling rate as 37%. Metallurgical loss of manganese was estimated to be about 1.7 times that recycled. This loss was mostly into slags from iron and steel production, from which recovery of manganese has yet to be shown economically feasible.

Jones, Thomas S.

2001-01-01

323

Toenail, Blood and Urine as Biomarkers of Manganese Exposure  

PubMed Central

Objective This study examined the correlation between manganese exposure and manganese concentrations in different biomarkers. Methods Air measurement data and work histories were used to determine manganese exposure over a workshift and cumulative exposure. Toenail samples (n=49), as well as blood and urine before (n=27) and after (urine, n=26; blood, n=24) a workshift were collected. Results Toenail manganese, adjusted for age and dietary manganese, was significantly correlated with cumulative exposure in months 7-9, 10-12, and 7-12 before toenail clipping date, but not months 1-6. Manganese exposure over a work shift was not correlated with changes in blood nor urine manganese. Conclusions Toenails appeared to be a valid measure of cumulative manganese exposure 7 to 12 months earlier. Neither change in blood nor urine manganese appeared to be suitable indicators of exposure over a typical workshift. PMID:21494156

Laohaudomchok, Wisanti; Lin, Xihong; Herrick, Robert F.; Fang, Shona C.; Cavallari, Jennifer M.; Christiani, David C.; Weisskopf, Marc G.

2011-01-01

324

Preparation of TEM samples of ferritic alloys  

Microsoft Academic Search

We describe techniques for electropolishing irradiated ferritic specimens for examination under the TEM in situations where the foil quality is of utmost importance. First, we describe some modifications to the standard technique for making plan-view specimens aimed at optimizing the foil quality. Second, we describe a technique for making plan-view specimens from a region of buried damage in a specimen

Z. Yao; S. Xu; M. L. Jenkins; M. A. Kirk

2008-01-01

325

Characteristics on left-handed ferrite waveguide  

Microsoft Academic Search

This paper treats filter characteristics of periodic structure in the ferrite waveguide under cutoff which include left-handed operation, resonance in the evanescent mode and mode concerned with Bragg reflection. Equivalent circuit model and simulation are used to get dispersion characteristics and scattering parameters. Left-handed characteristics at negative permeability region are discussed with backward wave phenomenon, which were confirmed with experiments

Kensuke Okubo; Makoto Tsutsumi

2010-01-01

326

Autonomic function in manganese alloy workers  

SciTech Connect

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 grinding repair of high manganese railway track and a convenience sample of three mild steel welders with lesser manganese exposure also referred because of cognitive or autonomic symptoms. Frog shop air manganese samples 9.6--10 years before and 1.2--3.4 years after the diagnosis of the index case exceeded 1.0 mg/m{sup 3} in 29% and 0.2 mg/m{sup 3} in 62%. Twenty-four-hour electrocardiographic (Holter) monitoring was used to determine the temporal variability of the heartrate (RR{prime} interval) and the rates of change at low frequency and high frequency. MMPI and MCMI personality assessment and short-term memory, figure copy, controlled oral word association, and symbol digit tests were used.

Barrington, W.W.; Angle, C.R.; Willcockson, N.K.; Padula, M.A. [Univ. of Nebraska Medical Center, Omaha, NE (United States)] [Univ. of Nebraska Medical Center, Omaha, NE (United States); Korn, T.

1998-07-01

327

Thermodynamic studies on lithium ferrites  

SciTech Connect

Thermodynamic studies on ternary oxides of Li-Fe-O systems were carried out using differential scanning calorimetry, Knudsen effusion mass spectrometry, and solid-state electrochemical technique based on fluoride electrolyte. Heat capacities of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined in the temperature range 127-861 K using differential scanning calorimetry. Gibbs energies of formation of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined using Knudsen effusion mass spectrometry and solid-state galvanic cell technique. The combined least squares fits can be represented as {Delta}{sub f}G{sub m}{sup o}(LiFe{sub 5}O{sub 8},s,T)/kJ mol{sup -1} ({+-}6)=-2341+0.6764(T/K) (588{<=}T/K{<=}971) {Delta}{sub f}G{sub m}{sup o}(LiFeO{sub 2},s,T)/kJ mol{sup -1} ({+-}3)=-708+0.1656(T/K) (569{<=}T/K{<=}1021) The temperature independent term of the above equations represents {Delta}{sub f}H{sup o}{sub m}(T{sub av}) and temperature dependent term represents negative change in entropy of the respective compounds. Thermodynamic analysis shows that LiFe{sub 5}O{sub 8}(s) is more stable compared to LiFeO{sub 2}(s). -- Graphical abstract: Comparison of {Delta}{sub f}G{sub m}{sup o}(T) of lithium ferrites determined using different techniques. Display Omitted Highlights: {yields} Thermodynamic studies on Li-Fe-O system using DSC, KEQMS and galvanic cell. {yields} Heat capacities of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined using DSC 127-861 K. {yields} {Delta}{sub f}G{sup o}{sub m} of these compounds were determined and compared. {yields} Thermodynamic tables for LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were constructed.

Rakshit, S.K., E-mail: swarup_kr@rediffmail.co [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Parida, S.C.; Naik, Y.P.; Chaudhary, Ziley Singh [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Venugopal, V. [Radiochemistry and Isotope Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2011-05-15

328

Synthesis and characterization of ZnS:Mn/ZnS core/shell nanoparticles for tumor targeting and imaging in vivo.  

PubMed

Fluorescence imaging technique has been used for imaging of biological cells and tissues in vivo. The Cd-free luminescent quantum dots conjugating with a cancer targeting ligand has been taken as a promising biocompatibility and low cytotoxicity system for targeted cancer imaging. This work reports the synthesis of fluorescent-doped core/shell quantum dots of water-soluble manganese-doped zinc sulfide. Quantum dots of manganese-doped zinc sulfide were prepared by nucleation doping strategy, with 3-mercaptopropionic acid as stabilizer at 90 in aqueous solution. The manganese-doped zinc sulfide nanoparticles exhibit strong orange fluorescence under UV irradiation, resistance to photo-bleaching, and low-cytotoxicity to HeLa cells. The structure and optical properties of nanoparticles were characterized by scanning electron microscope, X-ray diffraction, dynamic light scattering, and photoluminescence emission spectroscopy. Manganese-doped zinc sulfide nanoparticles conjugated with folic acid using 2,2'-(ethylenedioxy)-bis-(ethylamine) as the linker. The covalent binding of both 2,2'-(ethylenedioxy)-bis-(ethylamine) and folic acid on the surface of manganese-doped zinc sulfide nanoparticles probed by Fourier transform infrared spectroscopy detection. Furthermore, in vitro cytotoxicity assessment of manganese-doped zinc sulfide-folic acid probes use HeLa cells. The obtained fluorescent probes (manganese-doped zinc sulfide) were used for tumor targeting and imaging in vivo. The manganese-doped zinc sulfide-folic acid fluorescent probes which targeting the tumor cells in the body of nude mouse tumor model would emit orange fluorescence, when exposed to a 365?nm lamp. We investigate the biodistribution of the manganese-doped zinc sulfide-folic acid fluorescent probes in tumor mouse model by measuring zinc concentration in tissues. These studies demonstrate the practicality of manganese-doped zinc sulfide-folic acid fluorescent probes as promising platform for tumor targeting and imaging in vivo. PMID:22532407

Yu, Zhangsen; Ma, Xiying; Yu, Bin; Pan, Yuefang; Liu, Zhaogang

2013-08-01

329

Ethanol Gas Sensing of Mn-Doped CoFe$_{2}$O $_{4}$ Nanoparticles  

Microsoft Academic Search

Undoped and Mn-doped cobalt ferrite (CoFe O ) nanoparticles were synthesized and characterized for thermal conductivity and magnetic properties. Room temperature ferro- magnetism and an increase in saturation magnetization due to Mn doping (65.4 emu\\/g for 3 at.% of Mn and 20.8 emu\\/g for undoped CoFe O nanoparticles) are observed. The ethanol gas sensitivity of undoped and Mn-doped (3 at.%)

P. Indra Devi; N. Rajkumar; B. Renganathan; D. Sastikumar; K. Ramachandran

2011-01-01

330

Biogeochemical cycling of manganese in Oneida Lake, New York: whole lake studies of manganese  

NASA Technical Reports Server (NTRS)

Oneida Lake, New York is a eutrophic freshwater lake known for its abundant manganese nodules and a dynamic manganese cycle. Temporal and spatial distribution of soluble and particulate manganese in the water column of the lake were analyzed over a 3-year period and correlated with other variables such as oxygen, pH, and temperature. Only data from 1988 are shown. Manganese is removed from the water column in the spring via conversion to particulate form and deposited in the bottom sediments. This removal is due to biological factors, as the lake Eh/pH conditions alone can not account for the oxidation of the soluble manganese Mn(II). During the summer months the manganese from microbial reduction moves from the sediments to the water column. In periods of stratification the soluble Mn(II) builds up to concentrations of 20 micromoles or more in the bottom waters. When mixing occurs, the soluble Mn(II) is rapidly removed via oxidation. This cycle occurs more than once during the summer, with each manganese atom probably being used several times for the oxidation of organic carbon. At the end of the fall, whole lake concentrations of manganese stabilize, and remain at about 1 micromole until the following summer, when the cycle begins again. Inputs and outflows from the lake indicate that the active Mn cycle is primarily internal, with a small accumulation each year into ferromanganese nodules located in the oxic zones of the lake.

Aguilar, C.; Nealson, K. H.

1998-01-01

331

Effect of Carbon Dioxide on Availability of Manganese in Soil Producing Manganese Deficiency  

Microsoft Academic Search

A SERIES of experiments, extending over several years, in which potato plants were grown both in pots and in the field, in soil producing manganese deficiency, from the recently drained lake-bed at East Mailing Research Station, has led us to suspect the presence of some hitherto unexplained factor influencing manganese availability. The soil in question is an alluvial deposit containing

B. D. Bolas; G. B. Portsmouth

1948-01-01

332

Deposition of manganese sulfide and cadmium doped manganese sulfide thin films by M-CBD  

NASA Astrophysics Data System (ADS)

Un-doped and cadmium doped manganese sulfide thin films were prepared by M-CBD of aqueous solution onto glass substrates. The structural properties studied using X-ray diffraction showed that the un-doped manganese sulfide films exhibit amorphous structure; however Cd doped manganese sulfide films were crystalline. The surface morphological studies from SEM depicted the formation of clusters-like structure of un-doped manganese sulfide while the Cd doped film showed the nanocrystalline grains on the surface. From the optical studies, the absorbance in the wavelength range of 350-850 nm was found to increase after doping of Cd. The optical band gap was found to be 3.9 eV for un-doped manganese sulfide film and 3.7 eV for Cd doped films.

Pathan, Habib M.; Kale, Sampat S.; Pandit, Vishal K.

2012-06-01

333

Covalent hybrid of spinel manganese-cobalt oxide and graphene as advanced oxygen reduction electrocatalysts.  

PubMed

Through direct nanoparticle nucleation and growth on nitrogen doped, reduced graphene oxide sheets and cation substitution of spinel Co(3)O(4) nanoparticles, a manganese-cobalt spinel MnCo(2)O(4)/graphene hybrid was developed as a highly efficient electrocatalyst for oxygen reduction reaction (ORR) in alkaline conditions. Electrochemical and X-ray near-edge structure (XANES) investigations revealed that the nucleation and growth method for forming inorganic-nanocarbon hybrids results in covalent coupling between spinel oxide nanoparticles and N-doped reduced graphene oxide (N-rmGO) sheets. Carbon K-edge and nitrogen K-edge XANES showed strongly perturbed C-O and C-N bonding in the N-rmGO sheet, suggesting the formation of C-O-metal and C-N-metal bonds between N-doped graphene oxide and spinel oxide nanoparticles. Co L-edge and Mn L-edge XANES suggested substitution of Co(3+) sites by Mn(3+), which increased the activity of the catalytic sites in the hybrid materials, further boosting the ORR activity compared with the pure cobalt oxide hybrid. The covalently bonded hybrid afforded much greater activity and durability than the physical mixture of nanoparticles and carbon materials including N-rmGO. At the same mass loading, the MnCo(2)O(4)/N-graphene hybrid can outperform Pt/C in ORR current density at medium overpotentials with stability superior to Pt/C in alkaline solutions. PMID:22280461

Liang, Yongye; Wang, Hailiang; Zhou, Jigang; Li, Yanguang; Wang, Jian; Regier, Tom; Dai, Hongjie

2012-02-22

334

Electrocatalysis by design: Effect of the loading level of Au nanoparticles–MnOx nanoparticles binary catalysts on the electrochemical reduction of molecular oxygen  

Microsoft Academic Search

This study concerns the efficient electrochemical reduction of molecular oxygen (O2), in O2-saturated 0.1M KOH solution, to OH? through a four-electron reduction pathway by a novel binary catalyst that is comprised of two kinds of catalysts, i.e., Au nanoparticles (nano-Au) and manganese oxide nanoparticles (nano-MnOx) electrodeposited onto a relatively inert substrate, e.g., glassy carbon (GC) electrode. The nano-Au catalyst is

Mohamed S. El-Deab; Takeo Ohsaka

2007-01-01

335

Conventional and microwave hydrothermal synthesis of monodispersed metal oxide nanoparticles at liquid-liquid interface  

EPA Science Inventory

Monodispersed nanoparticles of metal oxide including ferrites MFe2O4 (M=, Ni, Co, Mn) and ¿-Fe2O3, Ta2O5 etc. have been synthesized using a water-toluene interface under both conventional and microwave hydrothermal conditions. This general synthesis procedure uses readily availab...

336

Cardiovascular Toxicities Upon Manganese Exposure  

PubMed Central

Manganese (Mn)-induced Parkinsonism has been well documented; however, little attention has been devoted to Mn-induced cardiovascular dysfunction. This review summarizes literature data from both animal and human studies on Mn’s effect on cardiovascular function. Clinical and epidemiological evidence suggests that the incidence of abnormal electrocardiogram (ECG) is significantly higher in Mn-exposed workers than that in the control subjects. The main types of abnormal ECG include sinus tachycardia, sinus bradycardia, sinus arrhythmia, sinister megacardia, and ST-T changes. The accelerated heartbeat and shortened P-R interval appear to be more prominent in female exposed workers than in their male counterparts. Mn-exposed workers display a mean diastolic blood pressure that is significantly lower than that of the control subjects, especially in the young and female exposed workers. Animal studies indicate that Mn is capable of quickly accumulating in heart tissue, resulting in acute or sub-acute cardiovascular disorders, such as acute cardiodepression and hypotension. These toxic outcomes appear to be associated with Mn-induced mitochondrial damage and interaction with the calcium channel in the cardiovascular system. PMID:16382172

Jiang, Yueming; Zheng, Wei

2014-01-01

337

Manganese in dwarf spheroidal galaxies  

E-print Network

We provide manganese abundances (corrected for the effect of the hyperfine structure) for a large number of stars in the dwarf spheroidal galaxies Sculptor and Fornax, and for a smaller number in the Carina and Sextans dSph galaxies. Abundances had already been determined for a number of other elements in these galaxies, including alpha and iron-peak ones, which allowed us to build [Mn/Fe] and [Mn/alpha] versus [Fe/H] diagrams. The Mn abundances imply sub-solar [Mn/Fe] ratios for the stars in all four galaxies examined. In Sculptor, [Mn/Fe] stays roughly constant between [Fe/H]\\sim -1.8 and -1.4 and decreases at higher iron abundance. In Fornax, [Mn/Fe] does not vary in any significant way with [Fe/H]. The relation between [Mn/alpha] and [Fe/H] for the dSph galaxies is clearly systematically offset from that for the Milky Way, which reflects the different star formation histories of the respective galaxies. The [Mn/alpha] behavior can be interpreted as a result of the metal-dependent Mn yields of type II and ...

North, P; Jablonka, P; Hill, V; Shetrone, M; Letarte, B; Lemasle, B; Venn, K A; Battaglia, G; Tolstoy, E; Irwin, M J; Primas, F; Francois, P

2012-01-01

338

Globally sustainable manganese metal production and use.  

PubMed

The "cradle to grave" concept of managing chemicals and wastes has been a descriptive analogy of proper environmental stewardship since the 1970s. The concept incorporates environmentally sustainable product choices-such as metal alloys utilized steel products which civilization is dependent upon. Manganese consumption is related to the increasing production of raw steel and upgrading ferroalloys. Nonferrous applications of manganese include production of dry-cell batteries, plant fertilizer components, animal feed and colorant for bricks. The manganese ore (high grade 35% manganese) production world wide is about 6 million ton/year and electrolytic manganese metal demand is about 0.7 million ton/year. The total manganese demand is consumed globally by industries including construction (23%), machinery (14%), and transportation (11%). Manganese is recycled within scrap of iron and steel, a small amount is recycled within aluminum used beverage cans. Recycling rate is 37% and efficiency is estimated as 53% [Roskill Metals and Minerals Reports, January 13, 2005. Manganese Report: rapid rise in output caused by Chinese crude steel production. Available from: http://www.roskill.com/reports/manganese.]. Environmentally sustainable management choices include identifying raw material chemistry, utilizing clean production processes, minimizing waste generation, recycling materials, controlling occupational exposures, and collecting representative environmental data. This paper will discuss two electrolytically produced manganese metals, the metal production differences, and environmental impacts cited to date. The two electrolytic manganese processes differ due to the addition of sulfur dioxide or selenium dioxide. Adverse environmental impacts due to use of selenium dioxide methodology include increased water consumption and order of magnitude greater solid waste generation per ton of metal processed. The use of high grade manganese ores in the electrolytic process also reduces the quantity of solid wastes generated during processing. Secondary aluminum facilities have reported hazardous waste generation management issues due to baghouse dusts from rotary furnaces processing selenium contaminated manganese alloys. Environmental impacts resulting from industry are represented by emission inventories of chemical releases to the air, water, and soil. The U.S. metals industry releases reported to EPA Toxic Release Inventory indicate the primary metals industry is the major source of metal air toxic emissions, exceeding electric utility air toxic emissions. The nonferrous metals industry is reported to be the Organization for Economic Co-operation and Development (OECD) most intensive airborne and land pollution source of bioaccumulative metals. However, total waste emissions from industries in the OECD countries have declined due to improving energy consumption. Emission registers and access are improving around the world. However, environmental databases for metal particulates have low confidence ratings since the majority of air toxic emissions are not reported, not monitored, or are estimated based on worst-case emission factors. Environmental assessments including biological monitoring are necessary to validate mandated particulate metal emission reductions and control technologies during metal processing. PMID:19467569

Hagelstein, Karen

2009-09-01

339

Determination of Plutonium-Beryllium Source Strength by Manganese Activation.  

National Technical Information Service (NTIS)

In this study the manganese-sulfate-bath technique was used to determine the total neutron output of a Plutonium-Beryllium neutron source. Activation trials were conducted using 4 different concentrations of manganese sulfate and 3 different size containe...

P. F. Whitworth

1988-01-01

340

High-Performance Manganese Oxide Catalysts for CO Oxidation  

Microsoft Academic Search

The catalytic activity of manganese dioxide samples in oxidation of CO and decomposition of hydrogen peroxide was studied. The promise of manganese dioxide obtained from fluorine-containing electrolytes as a catalyst for carbon monoxide oxidation was considered.

N. D. Ivanova; S. V. Ivanov; E. I. Boldyrev; G. V. Sokol'skii; I. S. Makeeva

2002-01-01

341

Morphological, magnetic and electronic structural studies of nanostructured spinel ferrites  

NASA Astrophysics Data System (ADS)

The scope of this thesis includes study of structural, magnetic and electronic properties of nanostructured ferrites with different morphology/geometries (e.g. core/shell and hollow nanoparticles), and non-stroichiomteric thin-films. In the case of core/shell, shell composition is varied and spin glass (SG) features due to the thick amorphous shells are explored. Exchange Bias (EB) for core/shell (ferromagnetic/SG) nanoparticles namely X33Fe 67/XFe67O4 (X = Co, Ni, Fe) is presented. Limitations in the synthesis of various other alloys by inert gas condensation (IGC) due to the difference in the melting points are discussed. The existence of SG phase in these nanoparticles with CoFe2O4 shell results in the enhancement in EB. This is attributed to the large bulk anisotropy constant of the shell compared to other spinel cubic ferrites. Both dc magnetization and ac susceptibility measurements revealed a SG like transition which occurs at unusually large spin freezing temperature (TF ˜ 175K). The SG nature of the transition is also confirmed by the field dependence of the freezing temperature (TF(H)) following the well-known Almeida-Thouless (AT) line, deltaT F ˜ H2/3. Particles exhibit a large exchange bias (HEB ˜ 1357Oe) arising from the core-shell (ferromagnetic-SG) coupling. The unusually high SG transition temperature and large exchange bias effects are attributed to a combination of several factors including the thickness of the amorphous oxide shell and large values of the exchange and anisotropy constants associated with the CoFe2O 4 shell. In another extreme case of disordered spin systems, we synthesized NPs with hollow morphology with intentional choice of material namely NiFe 2O4 (CoFe2O4) which has lowest (highest) bulk anisotropy constant among the spinel ferrites. The hollow NPs are synthesized by self-templating process utilizing coupled interfacial chemical reactions and Kirkendall effect between the core (X33Fe67) and the shell (XFe2O4) of the core/shell structure is described. Reaction temperature and time dependent structural and morphological transformations are presented in detail. NiFe2O4 hollow particles show lack of saturation, enhancement in EB and inverse trend in the blocking temperature as a function of particles size. These are explained as being due to stabilized spin disorder and surface anisotropy. Unlike solid NPs, hollow NPs are polycrystalline. Electronic structure studies are performed by photoemission which reveals that CoFe2O4 particles with hollow morphology have higher degree of inversion compared to solid NPs. Electronic structure in comparison with magnetic studies reveal that particles exhibit uncompensated spins unlike bulk where Neel's collinear spin alignment is expected. For CoFe2O 4, both morphologies show lack of saturation up to 7T of applied field and magnetic irreversibility exists up to 7T of cooling fields for the entire temperature range (10 to 300K). These effects are explained in terms of temperature dependent large bulk anisotropy constant of CoFe2O4. Strong influence of uncompensated spins for particles with hollow morphology is characterized by cooling the sample in large fields, up to (˜9T). Magnitude of horizontal shift is more than three times larger compared to that of particles with solid morphology. 11% vertical shift for particles with hollow morphology is observed, whereas solid particles do not show corresponding shift. Finally, off-stoichiometric NiFe2O4 films prepared by pulsed laser deposition at low pressures and relatively high substrate temperatures were studied. Details of electronic structure of the films are presented and compared with stoichiometric bulk counterpart. Significant amount of oxygen vacancies and enhanced cationic inversion for non-stoichiometric thin films is observed. Films show spin glass features which are contrary to the usual ferrimagnetic response of the bulk nickel ferrite and spin freezing temperature which lies above room temperature in low fields (cooling field ˜ 0.1T). Interestingly, an exceptionally large exchange bi

Jardim, Marcos; Moura Prata, Daniela

342

Acicular ferrite transformation in alloy-steel weld metals  

Microsoft Academic Search

In this paper, the morphology of acicular ferrite in alloy-steel weld metals has been investigated. The effect of the grain\\u000a size of prior austenite on acicular ferrite transformation has also been studied. It is found that acicular ferrite can form\\u000a in reheated weld metals when the austenite grain size is relatively large. On the other hand, classical sheaf-like bainite\\u000a will

J. R. Yang; H. K. D. H. Bhadeshia

1991-01-01

343

Magnetic-marker system using ferrite composite materials  

SciTech Connect

The author`s group has developed some new ferrite composite materials by mixing ferrite by-products with binders such as cement, asphalt cement and epoxy resin. The authors have also developed a magnetic marker sensing system consisting of the ferrite composite material used as a magnetic marker embedded in an asphalt pavement or other surface and a portable magnetic sensor. This system has been applied in a guide lane for the blind and in a speed meter for a motor vehicle.

Mayama, Masakazu [Hokkaido Institute of Technology, Sapporo (Japan)

1993-12-31

344

Efficiency analysis for a manganese-oxide-based thermochemical cycle  

Microsoft Academic Search

A thermochemical cycle for the solar production of hydrogen is proposed. The cycle includes: (1) the conversion of solar to chemical energy by the thermal reduction of manganese(III) oxide to manganese(II) oxide at temperatures below 1900K, (2) the production of hydrogen by reacting manganese(II) oxide with sodium hydroxide, and (3) the separation of manganese oxide from sodium hydroxide by a

M Sturzenegger; P Nüesch

1999-01-01

345

Nervous system effects of occupational manganese exposure on South African manganese mineworkers.  

PubMed

Occupational exposure to airborne manganese dust has been shown to produce adverse effects on the central nervous system. Four hundred and eighty-nine blue and white collar manganese mineworkers from South Africa were studied cross-sectionally to investigate the nervous system effects of medium to low occupational manganese exposures. The different facilities included underground mines, surface processing plants, and office locations. A job exposure matrix was constructed using routine occupational hygiene data. Exposure variables included years of service, a cumulative exposure index (CEI) and average intensity of exposure (AINT) across all jobs, and blood manganese. Endpoints included items from the Q16, WHO-NCTB, SPES, and Luria-Nebraska test batteries, and a brief clinical examination. Potential confounders and effect modifiers included age, level of education, past medical history including previous head injury, previous neurotoxic job exposures, tobacco use, alcohol use and home language. Associations were evaluated by multiple linear and logistic regression modeling. Average exposure intensity across all jobs was 0.21mg/m(3) manganese dust. Multivariate analyses showed that none of the symptom nor test results were associated with any measure of exposure including blood manganese, after adjustment for confounders. This relatively large null study indicates that manganese miners exposed on average across all jobs to MnO(2) at levels near the American Conference of Governmental Industrial Hygienists Threshold Limit Value (ACGIH TLV) are unlikely to have a subclinical neurotoxicity problem. PMID:12900078

Myers, Jonathan E; teWaterNaude, Jim; Fourie, Markus; Zogoe, H B Abie; Naik, Inakshi; Theodorou, Penny; Tassel, Halina; Daya, Aarti; Thompson, Mary Lou

2003-08-01

346

Synthesis and characterization of nickel and zinc ferrite nanocatalysts for decomposition of CO2 greenhouse effect gas.  

PubMed

The decomposition of CO2 over oxygen deficient nickel ferrite nanoparticles (NFNs) and zinc ferrite nanoparticles (ZFNs) at 573 K was studied. The oxidation states with fine structure of Fe/Ni or Fe/Zn species were also measured in NFNs and ZFNs catalysts, respectively. Oxygen deficiency of catalysts was obtained by reduction in hydrogen. Decomposition of CO2 into carbon and oxygen has been carried out within few minutes when it comes into contact with oxygen deficient catalysts through incorporation of oxygen into ferrite nanoparticles. Oxygen and carbon rather than CO were produced in the decomposition process. The complete decomposition of CO2 was possible because of higher degree of oxygen deficiency andsurface-to-volume ratio of the catalysts. The pre-edge XANES spectra of Fe species in both catalysts exhibit an absorbance feature at 7114 eV for the 1s to 3d transition which is forbidden by the selection rule in case of perfect octahedral symmetry. The EXAFS data showed that the NFNs had two central Fe atoms coordinated by primarily Fe-O and Fe-Fe with bond distances of 1.871 and 3.051 angstroms, respectively. In case of ZFNs these values are 1.889 and 3.062 A, respectively. Methane gas was produced during the reactivation of NFNs by flowing hydrogen gas. Decomposition of CO2, moreover, recovery of valuable methane using heat energy of offgas produced from power generation plant or steel industry is an appealing alternative for energy recovery. PMID:23763127

Lin, Kuen-Song; Adhikari, Abhijit Krishna; Wang, Chi-Yu; Hsu, Pei-Ju; Chan, Ho-Yang

2013-04-01

347

Tunable polarity of the Casimir force based on saturated ferrites  

NASA Astrophysics Data System (ADS)

We study the polarity of the Casimir force between two different parallel slabs separated by vacuum when the saturated ferrite materials under the influence of an external magnetic field are taken into consideration. Between the ordinary dielectric slab and the ferrite slab, repulsive Casimir force may be observed by adjusting the applied magnetic field. For the ferrite material, we consider the frequency dependence of the permeability modified by the external magnetic field to analyze the formation of the repulsive Casimir force. The restoring force, which means the transition of the force polarity from repulsion to attraction with the increasing slab separation, can also be obtained between two different ferrite slabs.

Zeng, Ran; Yang, Yaping

2011-01-01

348

Nanosized copper ferrite materials: Mechanochemical synthesis and characterization  

SciTech Connect

Nanodimensional powders of cubic copper ferrite are synthesized by two-steps procedure of co-precipitation of copper and iron hydroxide carbonates, followed by mechanochemical treatment. X-ray powder diffraction, Moessbauer spectroscopy and temperature-programmed reduction are used for the characterization of the obtained materials. Their catalytic behavior is tested in methanol decomposition to hydrogen and CO and total oxidation of toluene. Formation of nanosized ferrite material is registered even after one hour of milling time. It is established that the prolonging of treatment procedure decreases the dispersion of the obtained product with the appearance of Fe{sub 2}O{sub 3}. It is demonstrated that the catalytic behavior of the samples depends not only on their initial phase composition, but on the concomitant ferrite phase transformations by the influence of the reaction medium. -- Graphical abstract: It is demonstrated that the catalytic behavior of the obtained copper ferrites depends not only on their initial phase composition, but on the concomitant phase transformations by the influence of the reaction medium. Display Omitted Highlights: {yields} Two-step co-precipitation-ball-milling procedure for copper ferrites preparation. {yields} The phase composition of ferrites depends on the milling duration. {yields} Ferrites transforms under the reaction medium, which affects their catalytic behavior. {yields} Ferrites decompose to magnetite and carbides during methanol decomposition. {yields} Agglomeration and further crystallization of ferrite occur during toluene oxidation.

Manova, Elina [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria); Tsoncheva, Tanya, E-mail: tsoncheva@orgchm.bas.b [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia (Bulgaria); Paneva, Daniela [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria); Popova, Margarita [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia (Bulgaria); Velinov, Nikolay; Kunev, Boris; Tenchev, Krassimir; Mitov, Ivan [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria)

2011-05-15

349

Preparation of TEM samples of ferritic alloys.  

PubMed

We describe techniques for electropolishing irradiated ferritic specimens for examination under the TEM in situations where the foil quality is of utmost importance. First, we describe some modifications to the standard technique for making plan-view specimens aimed at optimizing the foil quality. Second, we describe a technique for making plan-view specimens from a region of buried damage in a specimen irradiated with 2 MeV Fe(+) ions. PMID:18316797

Yao, Z; Xu, S; Jenkins, M L; Kirk, M A

2008-06-01

350

Cold worked ferritic alloys and components  

DOEpatents

This invention relates to liquid metal fast breeder reactor and steam generator precipitation hardening fully ferritic alloy components which have a microstructure substantially free of the primary precipitation hardening phase while having cells or arrays of dislocations of varying population densities. It also relates to the process by which these components are produced, which entails solution treating the alloy followed by a final cold working step. In this condition, the first significant precipitation hardening of the component occurs during high temperature use.

Korenko, Michael K. (Wexford, PA)

1984-01-01

351

Recrystallization of stabilized ferritic stainless steel sheet  

NASA Astrophysics Data System (ADS)

An experimental study of the microstructural evolution attending recrystallization of cold-rolled Ti-stabilized ferritic stainless steel is presented. Particular attention is paid to the slow approach to full recrystallization. It is shown that this “sluggish” recrystallization can be attributed to the heterogeneity of microstructure and texture resulting from the processing of the material. In particular, it is shown that the presence of fine Ti(C,N) precipitates acts to significantly hinder the final approach to full recrystallization.

Sinclair, C. W.; Mithieux, J.-D.; Schmitt, J.-H.; Bréchet, Y.

2005-11-01

352

Manganese (II) induces chemical hypoxia by inhibiting HIF-prolyl hydroxylase: Implication in manganese-induced pulmonary inflammation  

SciTech Connect

Manganese (II), a transition metal, causes pulmonary inflammation upon environmental or occupational inhalation in excess. We investigated a potential molecular mechanism underlying manganese-induced pulmonary inflammation. Manganese (II) delayed HIF-1{alpha} protein disappearance, which occurred by inhibiting HIF-prolyl hydroxylase (HPH), the key enzyme for HIF-1{alpha} hydroxylation and subsequent von Hippel-Lindau(VHL)-dependent HIF-1{alpha} degradation. HPH inhibition by manganese (II) was neutralized significantly by elevated dose of iron. Consistent with this, the induction of cellular HIF-1{alpha} protein by manganese (II) was abolished by pretreatment with iron. Manganese (II) induced the HIF-1 target gene involved in pulmonary inflammation, vascular endothelial growth factor (VEGF), in lung carcinoma cell lines. The induction of VEGF was dependent on HIF-1. Manganese-induced VEGF promoted tube formation of HUVEC. Taken together, these data suggest that HIF-1 may be a potential mediator of manganese-induced pulmonary inflammation.

Han, Jeongoh [Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735 (Korea, Republic of); Lee, Jong-Suk [Laboratory of Physiology, College of Pharmacy, Yeungnam University, Gyeongsan (Korea, Republic of); Choi, Daekyu; Lee, Youna; Hong, Sungchae; Choi, Jungyun; Han, Songyi [Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735 (Korea, Republic of); Ko, Yujin; Kim, Jung-Ae [Laboratory of Physiology, College of Pharmacy, Yeungnam University, Gyeongsan (Korea, Republic of); Mi Kim, Young [Medicinal Chemistry, College of Pharmacy, Pusan National University, Busan (Korea, Republic of); Jung, Yunjin [Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735 (Korea, Republic of)], E-mail: jungy@pusan.ac.kr

2009-03-15

353

Essentiality, Toxicity, and Uncertainty in the Risk Assessment of Manganese  

Microsoft Academic Search

Risk assessments of manganese by inhalation or oral routes of exposure typically acknowledge the duality of manganese as an essential element at low doses and a toxic metal at high doses. Previously, however, risk assessors were unable to describe manganese pharmacokinetics quantitatively across dose levels and routes of exposure, to account for mass balance, and to incorporate this information into

William K. Boyes

2010-01-01

354

Brain manganese accumulation following systemic administration of different forms  

Microsoft Academic Search

The content and retention of manganese in the blood and brain of mice exposed to different forms of the metal was compared. Mice received an acute sc injection of manganese as the chloride or oxide (Mn3O4) or as the organic MMT. A single injection markedly elevated brain manganese concentrations within 1 day and elevated levels were maintained for at least

Gerald Gianutsos I; Michael D. Seltzer; Riyad Saymeh; Man-Li Wang Wu; R. G. Michel

1985-01-01

355

EFFECT OF MANGANESE ON GROI,IIHOF SPHAEROTILUS  

E-print Network

l-rrE I TLg EFFECT OF MANGANESE ON GROI,IIHOF SPHAEROTILUS DISCOPHORUS THESIS SUB spontaneously oxidize at physiological pH' whereas manganous manganese does not, the latter has been preferred ln modern studies of the problem. Work by Prav6 (f4) suggested that manganese autotrophy night exist

Luther, Douglas S.

356

Pwave Pairing and Colossal Magnetoresistance in Manganese Oxides  

E-print Network

P­wave Pairing and Colossal Magnetoresistance in Manganese Oxides Yong­Jihn Kim y Department that the existing experimental data of most manganese ox­ ides show the frustrated p­wave superconducting paid to the manganese oxides since the observa­ tion of colossal magnetoresistance (CMR). 1\\Gamma4

357

Original Research Manganese-Enhanced MRI Reveals Multiple  

E-print Network

Original Research Manganese-Enhanced MRI Reveals Multiple Cellular and Vascular Layers in Normal,6* Purpose: To use manganese-enhanced magnetic reso- nance imaging (MEMRI) at 25 Ã? 25 Ã? 800 mm3 to image different retinal and vascular layers in the rat retinas. Materials and Methods: Manganese

Duong, Timothy Q.

358

Terrestrial manganese-53 --A new monitor of Earth surface processes  

E-print Network

Terrestrial manganese-53 -- A new monitor of Earth surface processes Joerg M. Schaefer a,, Thomas of the terrestrial cosmogenic radionuclide manganese-53 (T1/2 =3.7 Ma) measured in thirteen samples from nine dolerite surfaces in the Dry Valleys, Antarctica. The terrestrial manganese-53 concentrations correlate

Winckler, Gisela

359

Growth of Manganese Oxide Nanostructures Alters the Layout of  

E-print Network

Growth of Manganese Oxide Nanostructures Alters the Layout of Adhesion on a Carbonate Substrate C H-volume microscopy and a silicon-nitride probe, we measure changes in adhesion when a patchy overgrowth of manganese for advancingthemechanisticmodelingofthefateandtransport of environmental contaminants (11, 12). Manganese oxide (MnOx) nanostructures grown

360

A universal scaling law to predict the efficiency of magnetic nanoparticles as MRI T(2)-contrast agents.  

PubMed

Magnetic particles are very efficient magnetic resonance imaging (MRI) contrast agents. In recent years, chemists have unleashed their imagination to design multi-functional nanoprobes for biomedical applications including MRI contrast enhancement. This study is focused on the direct relationship between the size and magnetization of the particles and their nuclear magnetic resonance relaxation properties, which condition their efficiency. Experimental relaxation results with maghemite particles exhibiting a wide range of sizes and magnetizations are compared to previously published data and to well-established relaxation theories with a good agreement. This allows deriving the experimental master curve of the transverse relaxivity versus particle size and to predict the MRI contrast efficiency of any type of magnetic nanoparticles. This prediction only requires the knowledge of the size of the particles impermeable to water protons and the saturation magnetization of the corresponding volume. To predict the T(2) relaxation efficiency of magnetic single crystals, the crystal size and magnetization - obtained through a single Langevin fit of a magnetization curve - is the only information needed. For contrast agents made of several magnetic cores assembled into various geometries (dilute fractal aggregates, dense spherical clusters, core-shell micelles, hollow vesicles…), one needs to know a third parameter, namely the intra-aggregate volume fraction occupied by the magnetic materials relatively to the whole (hydrodynamic) sphere. Finally a calculation of the maximum achievable relaxation effect - and the size needed to reach this maximum - is performed for different cases: maghemite single crystals and dense clusters, core-shell particles (oxide layer around a metallic core) and zinc-manganese ferrite crystals. PMID:23184784

Vuong, Quoc L; Berret, Jean-François; Fresnais, Jérôme; Gossuin, Yves; Sandre, Olivier

2012-07-01

361

Manganese in dwarf spheroidal galaxies  

NASA Astrophysics Data System (ADS)

We provide manganese abundances (corrected for the effect of the hyperfine structure) for a large number of stars in the dwarf spheroidal galaxies Sculptor and Fornax, and for a smaller number in the Carina and Sextans dSph galaxies. Abundances had already been determined for a number of other elements in these galaxies, including ? and iron-peak ones, which allowed us to build [Mn/Fe] and [Mn/?] versus [Fe/H] diagrams. The Mn abundances imply sub-solar [Mn/Fe] ratios for the stars in all four galaxies examined. In Sculptor, [Mn/Fe] stays roughly constant between [Fe/H] ~ -1.8 and -1.4 and decreases at higher iron abundance. In Fornax, [Mn/Fe] does not vary in any significant way with [Fe/H]. The relation between [Mn/?] and [Fe/H] for the dSph galaxies is clearly systematically offset from that for the Milky Way, which reflects the different star formation histories of the respective galaxies. The [Mn/?] behavior can be interpreted as a result of the metal-dependent Mn yields of Type II and Type Ia supernovae. We also computed chemical evolution models for star formation histories matching those determined empirically for Sculptor, Fornax, and Carina, and for the Mn yields of SNe Ia, which were assumed to be either constant or variable with metallicity. The observed [Mn/Fe] versus [Fe/H] relation in Sculptor, Fornax, and Carina can be reproduced only by the chemical evolution models that include a metallicity-dependent Mn yield from the SNe Ia. Based on observations made with the FLAMES-GIRAFFE multi-object spectrograph mounted on the Kuyen VLT telescope at ESO-Paranal Observatory (programs 171.B-0588, 074.B-0415 and 076.B-0146).Appendices are available in electronic form at http://www.aanda.org

North, P.; Cescutti, G.; Jablonka, P.; Hill, V.; Shetrone, M.; Letarte, B.; Lemasle, B.; Venn, K. A.; Battaglia, G.; Tolstoy, E.; Irwin, M. J.; Primas, F.; François, P.

2012-05-01

362

Comparative toxicokinetics of manganese chloride and methylcyclopentadienyl manganese tricarbonyl (MMT) in Sprague-Dawley rats.  

PubMed

The toxicokinetics of manganese (Mn) was investigated in male and female rats either following a single intravenous (iv) or oral dose of MnCl2 (6.0 mg Mn/kg), or following a single oral dose of methylcyclopentadienyl manganese tricarbonyl (MMT) (20 mg MMT/kg or 5.6 mg Mn/kg). The plasma concentrations of manganese were quantified by atomic absorption spectrophotometry (AAS). Upon iv administration of MnCl2, manganese rapidly disappeared from blood with a terminal elimination t1/2 of 1.83 h and CL8 of 0.43 L/h/kg. The plasma concentration-time profiles of manganese could be described by C = 41.9e(-424t) + 2.1e(-0.44t). Following oral administration of MnCl2, manganese rapidly entered the systemic circulation (Tmax = 0.25 h). The absolute oral bioavailability was about 13%. Oral dose of MMT resulted in a delayed Tmax(7.6 h), elevated Cmax (0.93 microg/ml), and prolonged terminal t1/2 (55.1 h). The rats receiving MMT had an apparent clearance (CL/F = 0.09 L/h x kg) about 37-fold less than did those who were dosed with MnCl2. Accordingly, the area under the plasma concentration-time curves (AUC) of manganese in MMT-treated rats was about 37-fold greater than that in MnCl2-treated rats. A gender-dependent difference in toxicokinetic profiles of plasma manganese was also observed. Female rats displayed a greater AUC than that of male rats. Although the apparent volume of distribution of manganese was similar in both sexes, the apparent clearance in males was about twice that observed in females. The results indicated that after oral administration, the MMT-derived manganese displayed higher and more prolonged plasma concentration-time profiles than MnCl2-derived manganese. Thus, MMT-derived manganese appeared likely to accumulate in the body following repeated exposure. PMID:10774811

Zheng, W; Kim, H; Zhao, Q

2000-04-01

363

Bacterial manganese reduction and growth with manganese oxide as the sole electron acceptor  

NASA Technical Reports Server (NTRS)

Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium, Alteromonas putrefaciens MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest that this bacterium uses manganic oxide as a terminal electron acceptor. It can also utilize a large number of other compounds as terminal electron acceptors; this versatility could provide a distinct advantage in environments where electron-acceptor concentrations may vary.

Myers, Charles R.; Nealson, Kenneth H.

1988-01-01

364

Effect of cation trapping on thermal stability of magnetite nanoparticles.  

PubMed

We investigate the effect of sodium trapping on thermal stability of magnetite (Fe3O4) nanoparticles. The pure magnetite nanoparticles incubated in sodium hydroxide solutions and subsequently washed with water to remove the excess sodium. The amount of sodium in magnetite is measured using atomic absorption spectroscopy. The size distribution obtained from Small angle X-ray scattering measurements show that particles are fairly monodisperse. The FTIR spectra of nanoparticles show transmission bands at 441 and 611 cm(-1) are due to the symmetric stretching vibrations (v) of Fe-O in octahedral and tetrahedral sites respectively. With 500 ppm of sodium ions (Na+) in magnetite, the cubic ferrite structure of maghemite (gamma-Fe2O3) to hexagonal hematite (alpha-Fe2O3) phase transition is enhanced by -150 degrees C in air. The Rietveld analysis of sodium doped magnetite nanoparticles show that above 99% of metastable gamma-Fe2O3 is converted to a thermodynamically stable alpha-Fe2O3 after air annealing at 700 degrees C. A decrease in enthalpy observed in doped magnetite unambiguously confirms that the activation energy for maghemite to hematite transition is increased due to the presence of trapped sodium ions. These results suggest that the trapped cations in ferrite nanoparticles can stabilize them by increasing the activation energy. PMID:24738360

Pati, S S; Philip, John

2014-06-01

365

Isotopic evidence for organic matter oxidation by manganese reduction in the formation of stratiform manganese carbonate ore  

Microsoft Academic Search

Unlike other marine-sedimentary manganese ore deposits, which are largely composed of manganese oxides, the primary ore at Molango (Hidalgo State, Mexico) is exclusively manganese carbonate (rhodochrosite, Mn-calcite, kutnahorite). Stable isotope studies of the carbonates from Molango provide critical new information relevant to the controversy over syngenetic and diagenetic models of stratiform manganese deposit formation. Negative δ¹³C values for carbonates from

P. M. Okita; J. B. Maynard; E. C. Spiker; E. R. Force

1988-01-01

366

The effect of tempering temperature on the features of phase transformations in the ferritic-martensitic steel EK-181  

NASA Astrophysics Data System (ADS)

Using the methods of dilatometry and differential scanning calorimetry, critical points of phase transformations in the low-activation ferritic-martensitic steel EK-181 (RUSFER-EK-181) are identified. The characteristic temperature intervals of precipitation of carbide phases are revealed. It is shown that particles of the metastable carbide M3C are formed within the temperature range (500-600) °C. Formation of the stable phases ?23?6 and V(CN) begins at the temperatures higher than ? = 650 °?. An important feature of microstructure after tempering at ? = 720 °? is high density of nanoparticles (?10 nm) of vanadium carbonitride V(CN).

Polekhina, N. A.; Litovchenko, I. Yu.; Tyumentsev, A. N.; Astafurova, ?. G.; Chernov, V. M.; Leontyeva-Smirnova, M. V.

2014-12-01

367

Friction and wear of single-crystal and polycrystalline maganese-zinc ferrite in contact with various metals  

NASA Technical Reports Server (NTRS)

Sliding friction experiments were conducted with single-crystal (SCF) and hot-pressed polycrystalline (HPF) manganese-zinc ferrite in contact with various metals. Results indicate that the coefficients of friction for SCF and HPF are related to the relative chemical activity of those metals in high vacuum. The more active the metal, the higher the coefficient of friction. The coefficients of friction for both SCF and HPF were the same and much higher in vacuum than in argon at atmospheric pressure. All the metals tested transferred to the surface of both SCF and HPF in sliding. Both SCF and HPF exhibited cracking and fracture with sliding. Cracking in SCF is dependent on crystallographic characteristics. In HPF, cracking depends on the orientation of the individual crystallites.

Miyoshi, K.; Buckley, D. H.

1977-01-01

368

Manganese Distribution in the Brain and Neurobehavioral Changes Following Inhalation Exposure of Rats to Three Chemical Forms of Manganese  

Microsoft Academic Search

The central nervous system is an important target for manganese (Mn) intoxication in humans; it may cause neurological symptoms similar to Parkinson’s disease. Manganese compounds emitted from the tailpipe of vehicles using methylcyclopentadienyl manganese tricarbonyl (MMT) are primarily Mn phosphate, Mn sulfate, and Mn phosphate\\/sulfate mixture. The purpose of this study is to compare the patterns of Mn distribution in

Louise Normandin; Linda Ann Beaupré; Fariba Salehi; Annie St.-Pierre; Greg Kennedy; Donna Mergler; Roger F Butterworth; Suzanne Philippe; Joseph Zayed

2004-01-01

369

Electron Energy-Loss Safe-Dose Limits for Manganese Valence Measurements in Environmentally Relevant Manganese Oxides  

E-print Network

Electron Energy-Loss Safe-Dose Limits for Manganese Valence Measurements in Environmentally Relevant Manganese Oxides Kenneth J. T. Livi,*, Brandon Lafferty,,§ Mengqiang Zhu,,# Shouliang Zhang, Anne Houssiniere, BP 32229, 44322 Nantes Cedex 3, France *S Supporting Information ABSTRACT: Manganese (Mn) oxides

Sparks, Donald L.

370

Manganese Cell Labeling of Murine Hepatocytes Using Manganese(III)-Transferrin  

PubMed Central

Manganese(III)-transferrin (Mn(III)-Tf) was investigated as a way to accomplish manganese-labeling of murine hepatocytes for MRI contrast. It is postulated that Mn(III)-Tf can exploit the same transferrin-receptor-dependent and -independent metabolic pathways used by hepatocytes to transport the iron analogue Fe(III)-Tf. More specifically, it was investigated whether manganese delivered by transferrin could give MRI contrast in hepatocytes. Comparison of the T1 and T2 relaxation times of Mn(III)-Tf and Fe(III)-Tf over the same concentration range showed that the r1 relaxivities of the two metalloproteins are the same in vitro; with little contribution from paramagnetic enhancement. The degree of manganese cell labeling following incubation for 2–7 h in 31.5 ?M Mn(III)-Tf was comparable to that of hepatocytes incubated in 500 ?M Mn2+ for 1 h. The intrinsic manganese tissue relaxivity between Mn(III)-Tf-labeled and Mn2+-labeled cells was found to be the same; consistent with Mn(III) being released from transferrin and reduced to Mn2+. For both treatment regimens, manganese uptake by hepatocytes appeared to saturate in the first 1–2 h of the incubation period and may explain why the efficiency of hepatocyte cell labeling by the two methods appeared to be comparable in spite of the ~16-fold difference in effective manganese concentration. Hepatocytes continuously released manganese, as detected by MRI, and this was the same for both Mn2+- and Mn(III)-Tf-labeled cells. Manganese release may be the result of normal hepatocyte function; much in the same way that hepatocytes excrete manganese into the bile in vivo. This approach exploits a biological process – namely receptor binding, endocytosis, and endosomal acidification – to initiate the release of an MRI contrast agent; potentially confering more specificity to the labeling process. The ubiquitous expression of transferrin receptors by eukaryotic cells should make Mn(III)-Tf particularly useful for manganese labeling of a wide variety of cells both in culture and in vivo. PMID:18546093

Sotak, Christopher H.; Sharer, Kathryn; Koretsky, Alan P.

2011-01-01

371

Comparative Toxicokinetics of Manganese Chloride and Methylcyclopentadienyl Manganese Tricarbonyl (MMT) in Sprague-Dawley Rats  

Microsoft Academic Search

The toxicokinetics of manganese (Mn) was investigated in male and female rats either following a single intravenous (iv) or oral dose of MnCl2 (6.0 mg Mn\\/kg), or following a single oral dose of methylcyclopentadienyl manganese tricarbonyl (MMT) (20 mg MMT\\/kg or 5.6 mg Mn\\/kg). The plasma concentrations of man- ganese were quantified by atomic absorption spectrophotometry (AAS). Upon iv administration

Wei Zheng; Hyaehwan Kim; Qiuqu Zhao

2000-01-01

372

Self-assembled mesoporous Co and Ni-ferrite spherical clusters consisting of spinel nanocrystals prepared using a template-free approach.  

PubMed

Based on a self-assembly strategy, spherical mesoporous cobalt and nickel ferrite nanocrystal clusters with a large surface area and narrow size distribution were successfully synthesized for the first time via a template-free solvothermal process in ethylene glycol and subsequent heat treatment. In this work, the mesopores in the ferrite clusters were derived mainly from interior voids between aggregated primary nanoparticles (with crystallite size of less than 7 nm) and disordered particle packing domains. The concentration of sodium acetate is shown herein to play a crucial role in the formation of mesoporous ferrite spherical clusters. These ferrite clusters were characterized in detail using wide-angle X-ray diffraction, thermogravimetric-differential thermal analysis, (57)Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, standard and high-resolution transmission electron microscopy, and other techniques. The results confirmed the formation of both pure-phase ferrite clusters with highly crystalline spinel structure, uniform size (about 160 nm) and spherical morphology, and worm-like mesopore structures. The BET specific surface areas and mean pore sizes of the mesoporous Co and Ni-ferrite clusters were as high as 160 m(2) g(-1) and 182 m(2) g(-1), and 7.91 nm and 6.87 nm, respectively. A model for the formation of the spherical clusters in our system is proposed on the basis of the results. The magnetic properties of both samples were investigated at 300 K, and it was found that these materials are superparamagnetic. PMID:21904731

Yu, Byong Yong; Kwak, Seung-Yeop

2011-10-21

373

Recyclable nano-size Pd catalyst generated in the multilayer polyelectrolyte films on the magnetic nanoparticle core  

Microsoft Academic Search

This work describes the preparation of Pd nanoparticles in multilayer polyelectrolyte films fabricated on a magnetic ferrite core by a layer-by-layer (LbL) self-assembly technique, and the relationship between catalytic activity and these hybrid core-shell nanocomposite structures in the hydrogenation of olefinic alcohols. The hydrogenation reaction seems to be only catalyzed by Pd nanoparticles in the outermost layer of the hybrid

Yuhong Wang; Jin-Kyu Lee

2007-01-01

374

Particulate Manganese in the Black Sea.  

National Technical Information Service (NTIS)

Manganese nodules are thought to form by the oxidation of Mn(II) to Mn(IV) at an active site, and the trace metal enrichments have been related to the surface chemistry of this oxidized product. Recent data from the Black Sea have shown the existence of a...

P. G. Brewer

1972-01-01

375

Metallurgy and Processing of Marine Manganese Nodules  

Microsoft Academic Search

This paper reviews the state of the art in processing and extraction of ocean floor manganese nodules. It briefly reviews the mining sites where the abundant rich nodules occur and also discusses the metal distribution in nodules in view of economical processing and extraction of these metal values.The paper discloses in a detailed manner the physical and chemical characteristics of

D. W. FUERSTENAU; K. N. HAN

1983-01-01

376

Original article Studies on differential manganese tolerance  

E-print Network

(Oryza sativa) cultivars were tested for their tolerance to different levels of man- ganese (Mn+2) (2.0 µ tested as markers of manganese toxicity. Measurements as early as 48 hours after the germination did with increased per- oxidase activity and decreased catalase activity in different cultivars of mung bean and rice

Boyer, Edmond

377

ADVERSE HEALTH EFFECTS FROM ENVIRONMENTAL MANGANESE EXPOSURE.  

EPA Science Inventory

The ubiquitous element, manganese (Mn), is an essential nutrient, but toxic at excessive exposure levels. Therefore, the US EPA set guideline levels for Mn exposure through inhalation (reference concentration-RfC=0.05 ?g/m3) and ingestion (reference dose-RfD=0.14 mg/kg/day (10 mg...

378

Kinetics of Redox Processes in Manganese Oxides  

Microsoft Academic Search

In this work, we studied specific features of redox processes in manganese oxides Mn 2 O 3 and Mn 3 O 4 . The maximal threshold particle size that ensures the irreversible transition of ? -Mn 2 O 3 into hausmannite was determined. In the narrow temperature range of 810— 820¡ë , an overcooled fine powder of hausmannite was found

V. B. Fetisov; A. V. Fetisov; N. V. Korchemkina; L. A. Ovchinnikova; E. A. Pastukhov; A. Ya. Fishman

2002-01-01

379

Risk Assessment of an Essential Element: Manganese  

Microsoft Academic Search

Manganese (Mn) is an essential element for humans, animals, and plants and is required for growth, development, and maintenance of health. Mn is present in most tissues of all living organisms and is present naturally in rocks, soil, water, and food. High-dose oral, parenteral, or inhalation exposures are associated with increased tissue Mn levels that may lead to development of

Annette B. Santamaria; Sandra I. Sulsky

2010-01-01

380

21 CFR 73.2775 - Manganese violet.  

Code of Federal Regulations, 2010 CFR

...ammonium pyrophosphate complex having the approximate formula: Mn(III)NH4 P2 O7 . (b) Specifications. Manganese...not more than 1 part per million. Total color, based on Mn content in “as is” sample, not less than 93 percent....

2010-04-01

381

Low-carbon manganese carburizing steels  

Microsoft Academic Search

High-manganese low-carbon steels may be a new and promising class of carburizing steels. They do not contain expensive elements or those in short supply, are simple in production, and possess high strength properties and sufficient plasticity of the core. The obtaining in the case of metastable austenite which becomes harder during service opens new possibilities for increasing the life of

L. S. Malinov; L. I. Yakushechkina; E. L. Malinova

1985-01-01

382

Novel microwave devices using tunable negative index metamaterials and ferrites  

Microsoft Academic Search

Next generation microwave devices require to be multifunctional for efficient, cost effective operation in light weight, low volume structures. A miniature tunable negative index metamaterial phase shifter and an ultra wideband phased array antenna have been designed using ferrite materials. Negative permeability ferrite material in combination with negative permittivity of plasmonic wires produces a tunable negative refractive index metamaterial (TNIM).

Patanjali V. Parimi; Peng Peyton; Joseph M. Kunze; Carmine Vittoria; Vincent G. Harris

2009-01-01

383

Performance of Ferrites in the Microwave Range (Abstract)  

Microsoft Academic Search

The discovery of microwave Faraday rotation in ferrites has opened up a whole new field of investigation and applications. An elementary explanation of the cause of Faraday rotation will be given with the aid of a model of a spinning electron, which can demonstrate ferromagnetic resonance and negative permeability. Some of the applications of ferrites to microwave circulators, modulators end

A. G. Fox

1953-01-01

384

Solubility of carbon in tetragonal ferrite in equilibrium with austenite  

E-print Network

Solubility of carbon in tetragonal ferrite in equilibrium with austenite Jae Hoon Jang a H. K. D. H carbon is mobile. To explain this, we report the first calculations of the solubility of carbon in tetragonal ferrite that is in equilibrium with austenite. It is found that the solubility is dramatically

Cambridge, University of

385

Retention of ferrite in AluminiumAlloyed TRIPassisted steels  

E-print Network

Retention of ­ferrite in Aluminium­Alloyed TRIP­assisted steels Young Joo Choi1, Dong­Woo Suh1 to probe the data. Solidification experiments are reported in order to test the non­ equilibrium retention here. The purpose of the present work was to study the retention of ­ferrite in detail using the TCFE6

Cambridge, University of

386

Effect of Zn-substitution on the structural and magnetic properties of Mn-Zn ferrites synthesized from spent Zn-C batteries  

NASA Astrophysics Data System (ADS)

The present study aimed at the production of manganese-zinc ferrites through the recycling process of spent Zn-C batteries. Firstly, the spent Zn-C batteries were dismantled, crushed and leached in nitric acid and the composition of the acid solution was analyzed using atomic absorption spectroscopy. Secondly, stoichimetric amounts of metal nitrates were used to adjust the metallic concentration and prepare respective Mn1-xZnxFe2O4 ferrites (x=0.2-0.8) through the urea auto-combustion method. The obtained ferrites were examined by X-ray diffraction and Fourier transform infrared for crystalline phase identification, transmission electron microscopy for particle size and morphology and vibrating sample magnetometer for magnetic properties. The obtained structural and magnetic properties such as lattice parameter, infrared band positions saturation magnetization and coercivity were used to estimate the proper cation distribution of the system. The magnetic measurements showed that the change in the values of saturation magnetization with increasing Zn-content can be described according to the cation distribution while, that in the coercivity values can be explained on the basis of the magneto-crystalline anisotropy.

Gabal, M. A.; Al-Luhaibi, R. S.; Al Angari, Y. M.

2013-12-01

387

Effect of rare earth radius and concentration on the structural and transport properties of doped Mn Zn ferrite  

NASA Astrophysics Data System (ADS)

Dielectric constant ( ?'), AC conductivity ( ?), and seebeck coefficient ( S) have been measured for the ferrite samples of the general formula Mn 0.5Zn 0.5R yFe 2O 4; where R=Dy, Gd, Sm, Ce, and La prepared by standard ceramic technique and sintered at 1200 °C with a heating rate 4 °C/min. X-ray diffractograms show that all samples posses the spinel structure with the appearance of small peaks representing secondary phases. There is a lowering in the porosity starting after Sm-doped samples due to the presence of the secondary phases, which limits the grain growth. Due to seebeck measurements the manganese-zinc (Mn-Zn) ferrite doped with the rare earth has been classified as P-type semiconductors. It is possible to increase the electrical resistivity by using a small quantity of Dy 3+ ions substitutions owing to the structural heterogeneity generated by the insulating intergranular layers. The isolation of the grains is the most promising approaches for further reduction in the eddy current losses at the operating frequencies.

Ateia, E.; Ahmed, M. A.; El-Aziz, A. K.

2007-04-01

388

Preparation of Mn, Ni, Co ferrite highly porous silica nanocomposite aerogels by an urea-assisted sol-gel procedure.  

PubMed

The preparation of highly porous MnFe2O4-SiO2 and NiFe2O4-SiO2 nanocomposite aerogels with high purity and homogeneity was successfully achieved by a sol-gel procedure involving urea-assisted co-gelation of the precursor phases firstly applied for the synthesis of CoFe2O4-SiO2. This method allows fast gelation, giving rise to aerogels with 97% porosity. The structural, morphological and textural characterization as a function of thermal treatments was carried out by a multitechnique approach confirming that, as in the case of CoFe2O4-SiO2, the formation of single nanocrystals of manganese ferrite and nickel ferrite with spinel structure occurs after heating at 750 degrees C and is complete at 900 degrees C when the high porosity typical of aerogels is still retained. Thermogravimetric analysis (TG), differential thermal analysis (DTA), N2-physisorption at 77 K, powder X-ray diffraction (XRD), and transmission electron microscopy (TEM) indicate that the compositional homogeneity, crystallite size, thermal stability, and porosity are controlled by the sol-gel parameters of the preparation. PMID:20352749

Loche, Danilo; Casula, Maria F; Falqui, Andrea; Marras, Sergio; Corrias, Anna

2010-02-01

389

Soil Manganese Enrichment from Industrial Inputs: A Gastropod Perspective  

PubMed Central

Manganese is one of the most abundant metal in natural environments and serves as an essential microelement for all living systems. However, the enrichment of soil with manganese resulting from industrial inputs may threaten terrestrial ecosystems. Several studies have demonstrated harmful effects of manganese exposure by cutaneous contact and/or by soil ingestion to a wide range of soil invertebrates. The link between soil manganese and land snails has never been made although these invertebrates routinely come in contact with the upper soil horizons through cutaneous contact, egg-laying, and feeding activities in soil. Therefore, we have investigated the direct transfer of manganese from soils to snails and assessed its toxicity at background concentrations in the soil. Juvenile Cantareus aspersus snails were caged under semi-field conditions and exposed first, for a period of 30 days, to a series of soil manganese concentrations, and then, for a second period of 30 days, to soils with higher manganese concentrations. Manganese levels were measured in the snail hepatopancreas, foot, and shell. The snail survival and shell growth were used to assess the lethal and sublethal effects of manganese exposure. The transfer of manganese from soil to snails occurred independently of food ingestion, but had no consistent effect on either the snail survival or shell growth. The hepatopancreas was the best biomarker of manganese exposure, whereas the shell did not serve as a long-term sink for this metal. The kinetics of manganese retention in the hepatopancreas of snails previously exposed to manganese-spiked soils was significantly influenced by a new exposure event. The results of this study reveal the importance of land snails for manganese cycling in terrestrial biotopes and suggest that the direct transfer from soils to snails should be considered when precisely assessing the impact of anthropogenic Mn releases on soil ecosystems. PMID:24454856

Bordean, Despina-Maria; Nica, Dragos V.; Harmanescu, Monica; Banatean-Dunea, Ionut; Gergen, Iosif I.

2014-01-01

390

Effect of Ti4+ ions doping on microstructure and dc resistivity of nickel ferrites  

NASA Astrophysics Data System (ADS)

Nanostructured nickel ferrites (NiFe2O4) were prepared by doping with Ti4+ ions using solid-state reaction route. Lowest grain size of 55 nm was achieved in the specimens with 20 mole% TiO2 doping. Magnetization in the specimens decreases with decreasing grain sizes. Lower volume fractions of ferrite phase due to dissociation of the magnetic phase into smaller particles by the disruption of super exchange interaction by the titanium substitution results a decrease in magnetizations. Coercivity showed an increasing trend. This was explained as arising due to multidomain/monodomain magnetic behavior of magnetic nanoparticles. Small polaron hopping conduction between Fe2+ and Fe3+ sites controls the dc electrical properties of the specimens. The presence of an interfacial amorphous phase between the sites is evident from Mott's analysis. Specimens containing 10 mole or more TiO2 and sintered at 1350 °C contain NiTiO3 as a secondary phase and show unusual dc conductivity.

Kundu, T. K.; Mishra, S.; Karak, N.; Barik, P.

2012-04-01

391

Higher crystallinity superparamagnetic ferrites: Controlled synthesis in lecithin gels and magnetic properties  

NASA Astrophysics Data System (ADS)

The synthesis of ?-Fe2O3 nanoparticles in a novel organohydrogel medium is reported. The hydrogel consists of the phospholipid species, lecithin together with the anionic surfactant AOT, water and a hydrocarbon, isoocatane. Transmission electron microscopy observations indicate that the particles are spherical and range in size from 15 to 25 nm. Superconducting quantum interference device characterizations show that the particles exhibit superparamagnetic behavior with a blocking temperature of 24 K (at an applied field of 50 G) and a coercivity of 1600 G at 2 K. The results are compared to the magnetic properties of the ?-Fe2O3 particles of the same size and shape synthesized in water-in-oil microemulsions (reverse micelles). It was found that both blocking temperature and the coercivity of the ferrites synthesized in the lecithin gel media was higher than those synthesized in the reverse micelles. Similar results can be found for cobalt ferrites. These findings reveal the sizes of the domains are the same for these two kinds of particles, while the crystallinity may be higher for the particles synthesized in the lecithin gel media. It is proposed that slow ionic species diffusion through the channels of the gel may lead to such increases in crystallinity during particle growth.

Li, Sichu; John, Vijay T.; Rachakonda, Suguna H.; Irvin, Glen C.; McPherson, Gary L.; O'Connor, Charles J.

1999-04-01

392

Fluorescent Nanoparticles  

NSDL National Science Digital Library

This site from Clemson University shows how fluorescence enables the tracking of nanoparticles in living cells. Illustrations include the fluorescence of different kinds of nanoparticles, close-up views of the fluorescent particles, and the fluorescent particles as seen within cells.

Mcneill, Jason

2008-04-16

393

Electrical transport behavior of nonstoichiometric magnesium-zinc ferrite  

SciTech Connect

This paper presents the direct current conductivity, alternate current conductivity and dielectric properties of nonstoichiometric magnesium-zinc ferrite below room temperature. The frequency exponent (s) of conductivity shows an anomalous temperature dependency. The magnitude of the temperature exponent (n) of dielectric permittivity strongly depends on frequency and its value decreases with increasing frequency. The grain boundary contribution is dominating over the grain contribution in conduction process and the temperature dependence of resistance due to grain and grain boundary contribution exhibits two activation regions. The ferrite shows positive alternating current magnetoconductivity. The solid state processing technique was used for the preparation of nanocrystalline ferrite powder from oxides of magnesium, zinc and iron. The X-ray diffraction methods were used in determining the structure and composition of obtained ferrite, while multimeter, impedance analyzer, liquid nitrogen cryostat and electromagnet were used in the study of conducting and dielectric properties of ferrite.

Ghatak, S. [Department of Physics, National Institute of Technology, Deemed University, Mahatma Gandhi Avenue, Durgapur 713209, West Bengal (India)] [Department of Physics, National Institute of Technology, Deemed University, Mahatma Gandhi Avenue, Durgapur 713209, West Bengal (India); Sinha, M. [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India)] [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Meikap, A.K., E-mail: meikapnitd@yahoo.com [Department of Physics, National Institute of Technology, Deemed University, Mahatma Gandhi Avenue, Durgapur 713209, West Bengal (India); Pradhan, S.K. [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India)] [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India)

2010-08-15

394

Bismuth Substituted Zinc Ferrite: A New Room Temperature Multiferroic  

NASA Astrophysics Data System (ADS)

Zinc ferrite in nano and bulk form has been studied by many researchers. It has normal spinel structure with Tc of 10 K. It also has been reported that ball milled zinc ferrite shows inversion. In the present work, substitution of Bi3+ ions in zinc ferrite has been attempted. Bismuth substituted zinc ferrite sample with chemical formula ZnBi0.04Fe1.96O4 was synthesized. The variation of dielectric constant with frequency at different temperatures and its variation with temperature at different frequencies are reported in this paper. The maxima observed in the temperature variation curve at about 550 K indicates the multiferroic behaviour of bismuth doped zinc ferrite. Hysteresis loop measurement using SQUID showed the room temperature magnetic behaviour.

Bhatt, Kapil K.; Gurada, Chetan V.; Kothari, D. C.

2011-06-01

395

The Structure and Properties of Plasma Sprayed Iron Oxide Doped Manganese Cobalt Oxide Spinel Coatings for SOFC Metallic Interconnectors  

NASA Astrophysics Data System (ADS)

Manganese cobalt oxide spinel doped with Fe2O3 was studied as a protective coating on ferritic stainless steel interconnects. Chromium alloying causes problems at high operation temperatures in such oxidizing conditions where chromium compounds evaporate and poison the cathode active area, causing the degradation of the solid oxide fuel cell. In order to prevent chromium evaporation, these interconnectors need a protective coating to block the chromium evaporation and to maintain an adequate electrical conductivity. Thermal spraying is regarded as a promising way to produce dense and protective layers. In the present work, the ceramic Mn-Co-Fe oxide spinel coatings were produced by using the atmospheric plasma spray process. Coatings with low thickness and low amount of porosity were produced by optimizing deposition conditions. The original spinel structure decomposed because of the fast transformation of solid-liquid-solid states but was partially restored by using post-annealing treatment.

Puranen, Jouni; Lagerbom, Juha; Hyvärinen, Leo; Kylmälahti, Mikko; Himanen, Olli; Pihlatie, Mikko; Kiviaho, Jari; Vuoristo, Petri

2011-01-01

396

Preparation of medical magnetic nanobeads with ferrite particles encapsulated in a polyglycidyl methacrylate (GMA) for bioscreening  

SciTech Connect

Ferrite nanoparticles (an intermediate between Fe{sub 3}O{sub 4} and {gamma}-Fe{sub 2}O{sub 3}), {approx}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 ({approx}12 emu/g)

Nishibiraki, H.; Kuroda, C.S.; Maeda, M.; Matsushita, N.; Abe, M.; Handa, H. [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho Midori-ku, Yokohama 226-8503 (Japan)

2005-05-15

397

Surface driven effects on magnetic properties of antiferromagnetic LaFeO3 nanocrystalline ferrite  

NASA Astrophysics Data System (ADS)

LaFeO3 nanocrystalline ferrites were synthesized through sol-gel method in different size distributions and the effect of finite size on magnetic properties is investigated. Results of magnetization and Mössbauer measurements show that superparamagnetism and weak ferromagnetic behavior in some of the size distributions. The origin of the superparamagnetism is from fine particles similar to ferromagnetic single domains and the weak ferromagnetism comes from surface spin disorder caused by Dzyaloshinskii-Moriya interaction. The magnetic ground state of LaFeO3 nanoparticles differs from that of bulk, and the ground state is dictated by the finite size effect because density of states depends on the dimensionality of the sample.

Sendil Kumar, A.; Manivel Raja, M.; Bhatnagar, Anil K.

2014-09-01

398

Effect of ultrasonic treatment on tensile properties of PLA/LNR/NiZn ferrite nanocomposite  

SciTech Connect

The influence of sonication treatment time on the morphological and mechanical properties of LNR/PLA composite impregnated with different filler loadings of NiZn ferrite nanoparticles was investigated. The nanocomposite was prepared using melt blending method with assistance of ultrasonic treatment of 0, 1 and 2 hrs. Structural characterization of the nanocomposites was examined using scanning electron microscopy (SEM) with their elemental composition being confirmed by energy dispersive X-ray spectroscopy (EDX). The tensile properties of LNR/PLA composite treated with different ultrasonication times have improved with increasing magnetic nanofiller signature in the nanocomposite. Further, the optimum sonication time of 1 hr was found to produce nanocomposite with maximum tensile properties.

Shahdan, Dalila; Ahmad, Sahrim Hj.; Flaifel, Moayad Husein [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

2013-11-27

399

Soft ferrite cores characterization for integrated micro-inductors  

NASA Astrophysics Data System (ADS)

Low-profile soft ferrite films constitute a competitive solution for the integration of micro-inductors on silicon in low-power medium frequency dc–dc conversion applications. The high resistivity of soft ferrites is indeed a major advantage for operating frequencies in the range of 5‒10 MHz. We have studied several soft ferrites, including commercial ferrite films and ferrites made in-house. Test inductors were fabricated at a wafer level using micro-machining and assembling techniques. The proposed process is based on a sintered ferrite core placed between thick electroplated copper windings. The low-profile ferrite cores of 1.2  ×  2.6  ×  0.1 mm3 were produced by two methods using green tape-cast films or ferrite powders. This article presents the magnetic characterization of the fabricated ferrite cores, cut and printed in a rectangular shape and sintered at different temperatures. Comparisons are made in order to find the best material for the core that can offer micro-inductors a high inductance in the range of 200–1000 nH at 6 MHz, and that generate the smallest losses. Thanks to a test inductor, it is demonstrated that with a commercial ferrite core, an inductance density of 215 nH mm−2 up to 6 MHz could be reached. Extracted losses at 6 MHz, under 10 mT are in the range of 0.7 to 2.5 W cm−3.

Nguyen, Yen Mai; Bourrier, David; Charlot, Samuel; Valdez-Nava, Zarel; Bley, Vincent; Combettes, Céline; Lopez, Thomas; Laur, Jean-Pierre; Brunet, Magali

2014-10-01

400

Synthesis of Nickel-Zinc Ferrites in RF Thermal Plasma Reactor J. Szpvlgyi1,2*  

E-print Network

Synthesis of Nickel-Zinc Ferrites in RF Thermal Plasma Reactor J. Szépvölgyi1,2* , I. Mohai1 , L. In this paper results of thermal plasma synthesis of nanosized nickel-zinc ferrites from oxide powders: nickel-zinc ferrites, thermal plasma, synthesis Introduction Nickel-zinc ferrites are widely used

Gubicza, Jenõ

401

Analysis of delta-ferrite data from production stainless steel pipe welds  

Microsoft Academic Search

An American Society of Mechanical Engineers task group on stainless steel weld materials was organized to determine the need for ferrite measurements of production welds required by the US Nuclear Regulatory Commission Regulatory Guide 1.31 (Rev. 1). The task group studied paired ferrite measurements (i.e., calculated and measured ferrite numbers (FNs) for the material qualifications versus measured ferrite numbers for

T. L. Hebble; D. A. Canonico; D. P. Edmonds; G. M. Goodwin; R. K. Nanstad

1984-01-01

402

Tunable RF Cavities Using Orthogonally Biased Ferrite  

SciTech Connect

Originally conceived as a solution for FFAG applications, a new compact RF cavity design that tunes rapidly over various frequency ranges can be used to upgrade existing machines. The design being developed uses orthogonally biased garnet cores for fast frequency tuning and liquid dielectric to adjust the frequency range and to control the core temperature. We describe measurements of candidate ferrite and dielectric materials. The first use of the new cavity concept will be for improvements to the 8 GeV Fermilab Booster synchrotron.

Johnson, R.P.; Alsharo'a, M.; Ankenbrandt, C.M.; Entchevitch, I.; Griffin, J.E.; /Muons Inc., Batavia; Moretti, A.; Popovic, M.; Tomlin, R.; /Fermilab

2009-05-01

403

Maternal and early life exposure to manganese in rural Bangladesh.  

PubMed

Manganese exposure and biomarker concentrations during early pregnancy and lactation were investigated in 408 women living in an area with elevated concentrations of both arsenic and manganese in drinking water derived from wells. About 40% of the water samples had manganese concentrations above the World Health Organization's guideline value and showed a strong inverse correlation with arsenic concentrations. Water manganese was found to correlate to urine concentrations, but not to blood or breast milk concentrations. No correlations were found among manganese concentrations in urine, blood, or breast milk. Compared to other populations, manganese concentrations in both urine and blood, but not breast milk, were elevated in the Bangladeshi women and more similar to those of occupationally exposed groups. The lack of associations with water manganese is likely due to variable exposure via water and food, and differences in bioavailability, as well as a complex and/or strict regulation of intestinal manganese absorption, in turn being influenced by nutritional as well as physiological and genetic factors. The results indicate that elevated maternal manganese exposure does not necessarily lead to exposure of breast-fed infants, stressing the importance of breast feeding in high manganese areas. However, the implications of fetal exposurefrom elevated maternal exposure need further investigation. PMID:19452922

Ljung, Karin S; Kippler, Maria J; Goessler, Walter; Grandér, G Margaretha; Nermell, Barbro M; Vahter, Marie E

2009-04-01

404

A simple route to synthesize manganese germanate nanorods  

SciTech Connect

Manganese germanate nanorods have been synthesized by a simple route using germanium dioxide and manganese acetate as the source materials. X-ray diffraction observation shows that the nanorods are composed of orthorhombic and monoclinic manganese germanate phases. Scanning electron microscopy and transmission electron microscopy observations display that the manganese germanate nanorods have flat tips with the length of longer than 10 micrometers and diameter of 60-350 nm, respectively. The role of the growth conditions on the formation of the manganese germanate nanorods shows that the proper selection and combination of the growth conditions are the key factor for controlling the formation of the manganese germanate nanorods. The photoluminescence spectrum of the manganese germanate nanorods exhibits four fluorescence emission peaks centered at 422 nm, 472 nm, 487 nm and 530 nm showing the application potential for the optical devices. - Research Highlights: {yields} Manganese germanate nanorods have been synthesized by simple hydrothermal process. {yields} The formation of manganese germanate nanorods can be controlled by growth conditions. {yields} Manganese germanate nanorods exhibit good PL emission ability for optical device.

Pei, L.Z., E-mail: lzpei1977@163.com; Yang, Y.; Yuan, C.Z.; Duan Taike; Zhang Qianfeng

2011-06-15

405

Manganese binding proteins in human and cow's milk  

SciTech Connect

Manganese nutrition in the neonatal period is poorly understood, due in part to a lack of information on the amount of manganese in infant foods and its bioavailability. Since the molecular localization of an element in foods is one determinant of its subsequent bioavailability, a study was made of the binding of manganese in human and cow's milk. An extrinsic label of /sup 54/Mn was shown to equilibrate isotopically with native manganese in milks and formulas. Milk samples were separated into fat, casein and whey by ultracentrifugation. In human milk, the major part (71%) of manganese was found in whey, 11% in casein and 18% in the lipid fraction. In contrast, in cow's milk, 32% of total manganese was in whey, 67% in casein and 1% in lipid. Within the human whey fraction, most of the manganese was bound to lactoferrin, while in cow's whey, manganese was mostly complexed to ligands with molecular weights less than 200. The distribution of manganese in formulas was closer to that of human milk than of cow's milk. The bioavailability of manganese associated with lactoferrin, casein and low molecular weight complexes needs to be assessed.

Loennerdal, B.; Keen, C.L.; Hurley, L.S.

1985-03-01

406

Manganese oxide cathodes for rechargeable batteries  

NASA Astrophysics Data System (ADS)

Manganese oxides are considered as promising cathodes for rechargeable batteries due to their low cost and low toxicity as well as the abundant natural resources. In this dissertation, manganese oxides have been investigated as cathodes for both rechargeable lithium and alkaline batteries. Nanostructured lithium manganese oxides designed for rechargeable lithium cells have been synthesized by reducing lithium permanganate with methanol or hydrogen in various solvents followed by firing at moderate temperatures. The samples have been characterized by wet-chemical analyses, thermal methods, spectroscopic methods, and electron microscopy. It has been found that chemical residues in the oxides such as carboxylates and hydroxyl groups, which could be controlled by varying the reaction medium, reducing agents, and additives, make a significant influence on the electrochemical properties. The Li/Mn ratio in the material has also been found to be a critical factor in determining the rechargeability of the cathodes. The optimized samples exhibit a high capacity of close to 300 mAh/g with good cyclability and charge efficiency. The high capacity with a lower discharge voltage may make these nanostructured oxides particularly attractive for lithium polymer batteries. The research on the manganese oxide cathodes for alkaline batteries is focused on an analysis of the reaction products generated during the charge/discharge processes or by some designed chemical reactions mimicking the electrochemical processes. The factors influencing the formation of Mn3O4 in the two-electron redox process of delta-MnO2 have been studied with linear sweep voltammetry combined with X-ray diffraction. The presence of bismuth, the discharge rate, and the microstructure of the electrodes are found to affect the formation of Mn3O4, which is known to be electrochemically inactive. A faster voltage sweep and a more intimate mixing of the manganese oxide and carbon in the cathode are found to suppress the formation of Mn3O4. Bismuth has also been found to be beneficial in the one-electron process of gamma-MnO 2 when incorporated into the cathode. The results of a series of chemical reactions reveal that bismuth is blocking some reaction paths leading to the unwanted birnessite or Mn3O4. Barium is also found to play a similar role, but it is less effective than bismuth for the same amount of additive. Optimization of the additives has the potential to make the rechargeable alkaline cells based on manganese oxides to successfully compete with other rechargeable systems due to their low cost, environmental friendliness, and excellent safety features.

Im, Dongmin

407

R-curve behavior in ferrite ceramics  

SciTech Connect

The unusual dependence of the fracture mode of ferrite ceramics on the stress intensity factor in the subcritical crack growth regime was used to create flaws with different concentrations of crack-interface bridges. Flaws with numerous bridges were produced by indenting under dry silicone oil, while flaws with essentially no bridges were produced by indenting under water. Plots of log failure stress as a function of log indenter load for the two types of flaws reflect the differences in bridging. Those with extensive bridging showed pronounced R-curve behavior. The curve for those initially devoid of bridges showed no plateau but did show deviations from a {minus}1/3 slope that correspond to those predicted by Bennison and Lawn for this type of flaw. The ferrite studies was 62.4 Fe{sub 2}O{sub 3} 26.6 MnO, 11.2nO, and .04 V{sub 2}O{sub 5}. 10 figs.

Beauchamp, E.K.; Monroe, S.L.

1990-01-01

408

Manganese-Cobalt Mixed Spinel Oxides as Surface Modifiers for Stainless Steel Interconnects of Solid Oxide Fuel Cells  

SciTech Connect

Ferritic stainless steels are promising candidates for interconnect applications in low- and mid-temperature solid oxide fuel cells (SOFCs). A couple of issues however remain for the particular application, including the chromium poisoning due to chromia evaporation, and long-term surface and electrical stability of the scale grown on these steels. Application of a manganese colbaltite spinel protection layer on the steels appears to be an effective approach to solve the issues. For an optimized performance, Mn{sub 1+x}Co{sub 2-x}O{sub 4} (-1 {le} x {le} 2) spinels were investigated against properties relative for protection coating applications on ferritic SOFC interconnects. Overall it appears that the spinels with x around 0.5 demonstrate a good CTE match to ceramic cell components, a relative high electrical conductivity, and a good thermal stability up to 1,250 C. This was confirmed by a long-term test on the Mn{sub 1.5}Co{sub 1.5}O{sub 4} protection layer that was thermally grown on Crofer22 APU, indicating the spinel protection layer not only significantly decreased the contact resistance between a LSF cathode and the stainless steel interconnects, but also inhibited the sub-scale growth on the stainless steels.

Xia, Gordon; Yang, Z Gary; Stevenson, Jeffry W.

2006-11-06

409

Simulations of ferrite-dielectric-wire composite negative index materials  

NASA Astrophysics Data System (ADS)

We have performed extensive finite difference time domain (FDTD) simulations to design ferrite based negative index of refraction (NIM) composites. Our simulations center on the use of Barium M type ferrite with in-plane anisotropy. A wire grid is employed to provide negative permittivity. The ferrite and wire grid interact to provide both negative and positive index of refraction transmission peaks in the vicinity of the BaM resonance. We find that the wires and the ferrite must be spatially separated by a low loss dielectric (Mylar). The ferrite and dielectric media are modeled as thin lamina with a mono-directional wire grid centered in the dielectric lamina. The ferrite and dielectric lamina are paired with combined thickness equal to the square wire grid lattice distance. We assume the presence of a in plane orienting magnetic field. Working with thin planar oriented ferrite lamina implies that the composites will have a negative index in only one direction of propagation. Notwithstanding the extreme anisotropy in the index of refraction of the composite, negative refraction is seen at the composite air interface allowing the construction of a focusing concave lens with magnetically tunable focal length.

Rachford, Frederic; Armstead, Douglas; Harris, Vincent; Vittoria, Carmine

2007-03-01

410

Electrical and thermal behavior of PS/ferrite composite  

NASA Astrophysics Data System (ADS)

This work aims to study the effect of gamma radiation on the structure, thermal and electrical properties of PS/ferrite composite. The Ni0.6Cd0.4Fe2-xSmxO4 was prepared using a conventional sintering ceramic process. Ferrite powder and Styrene was mixed and achieve polymerization process by gamma irradiation at 50 kGy. The composite samples have single spinel phase structure. Stability of the crystalline structure and no phase transition due to irradiation are found. The bulk density decreases whereas X-ray density increases with increasing Sm contents for both ferrite and PS/ferrite. The tetrahedral radii rA remains constant with Sm content but octahedral radii rB increases for both ferrite and PS/ferrite composite. The grain size shows increasing trend for PS/ferrite composite. The PS nearly coat the grains and so their boundaries become faint and not sharp. The gamma radiation transfer Fe3+ to Fe2+ due to its ionizing effect.The Fe2+ occupy octahedral site and the stretching vibration of its bond with oxygen (Fe2+-O2-) gives absorption at about 392 cm-1, near octahedral absorption at 462 cm-1.The PS/Ni0.6Cd0.4SmxFe2-xO4 composite becomes thermally more stable than pure polystyrene. The activation energy of conduction E? has a small values and in the range of hopping conduction mechanism.

Ashour, A. H.; Hemeda, O. M.; Heiba, Z. K.; Al-Zahrani, S. M.

2014-11-01

411

Ferrite Effects in Fe-Mn-Al-C Triplex Steels  

NASA Astrophysics Data System (ADS)

In order to determine the ferrite effect on tensile properties of Fe-28.8Mn-9.4Al-C Triplex steels, four Triplex steel sheets with different carbon contents were solution treated under various conditions leading to different ferrite fractions ranging from 0 to 39 pct. This approach was used as it was very difficult to prepare samples with a wide range of ferrite contents from only one grade. However, in order to isolate the ferrite effect from this approach, it was necessary to precisely know the effect of the austenite carbon content and that of the austenite grain size on tensile properties of fully austenitic samples. This is why, a preliminary study was performed to assess these two effects, which required a thorough analysis of the microstructures of the investigated samples combining electron backscattered diffraction experiments and transmission electron microscopy observations. The study of fully austenitic samples led us to the conclusion that a decrease in the austenite grain size leads to higher strength and lower elongation and that the austenite carbon content has a greatly significant influence on tensile properties. However, this influence was difficult to estimate with a very good accuracy. Finally, the study of samples with different ferrite contents showed that ferrite had a positive effect on strength when its content was lower than 5 pct. In contrast, a higher content of ferrite (more than 30 pct) has a deleterious effect on mechanical properties.

Etienne, Auriane; Massardier-Jourdan, Véronique; Cazottes, Sophie; Garat, Xavier; Soler, Michel; Zuazo, Ian; Kleber, Xavier

2014-01-01

412

Glutamate\\/Aspartate Transporter (GLAST), Taurine Transporter and Metallothionein mRNA Levels are Differentially Altered in Astrocytes Exposed to Manganese Chloride, Manganese Phosphate or Manganese Sulfate  

Microsoft Academic Search

Manganese (Mn)-induced neurotoxicity can occur due to environmental exposure (air pollution, soil, water) and\\/or metabolic aberrations (decreased biliary excretion). High brain manganese levels lead to oxidative stress, as well as alterations in neurotransmitter metabolism with concurrent neurobehavioral deficits. Based on the few existing studies that have examined brain regional Mn concentration, it is likely that in pathological conditions, Mn concentration

Keith M. Erikson; Robert L. Suber; Michael Aschner

2002-01-01

413

International Strategic Minerals Inventory summary report; manganese  

USGS Publications Warehouse

Major world resources of manganese, a strategic mineral commodity, are described in this summary report of information in the International Strategic Minerals Inventory {ISMI). ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, and the United States of America. This report, designed to be of benefit to policy analysts, contains two parts. Part I presents an overview of the resources and potential supply of manganese on the basis of inventory information. Part II contains tables of some of the geologic information and mineral-resource and production data that were collected by ISMI participants.

DeYoung, John H.; Sutphin, David M.; Cannon, William F.

1984-01-01

414

Nickel hydroxide/cobalt-ferrite magnetic nanocatalyst for alcohol oxidation.  

PubMed

A magnetically separable, active nickel hydroxide (Brønsted base) coated nanocobalt ferrite catalyst has been developed for oxidation of alcohols. High surface area was achieved by tuning the particle size with surfactant. The surface area of 120.94 m2 g(-1) has been achieved for the coated nanocobalt ferrite. Improved catalytic activity and selectivity were obtained by synergistic effect of transition metal hydroxide (basic hydroxide) on nanocobalt ferrite. The nanocatalyst oxidizes primary and secondary alcohols efficiently (87%) to corresponding carbonyls in good yields. PMID:25075969

Bhat, Pooja B; Inam, Fawad; Bhat, Badekai Ramachandra

2014-08-11

415

Physicomechanical and magnetic properties of neoprene based rubber ferrite composites  

Microsoft Academic Search

Fine (approximately 18nm) particles of nickel ferrite were synthesized\\u000a by the sol-gel technique, and their structural properties were evaluated\\u000a by X-ray diffraction. Neoprene-based rubber ferrite composites were\\u000a prepared by incorporating these nickel ferrite powders in the rubber\\u000a matrix according to a specific recipe. The cure characteristics were\\u000a analyzed, and the samples were molded into particular shapes whose\\u000a properties were determined

K. H. Prema; Philip Kurian; P. A. Joy; M. R. Anantharaman

2008-01-01

416

Manganese accumulation in the brain: MR imaging  

Microsoft Academic Search

Manganese (Mn) accumulation in the brain is detected as symmetrical high signal intensity in the globus pallidi on T1-weighted\\u000a MR images without an abnormal signal on T2-weighted images. In this review, we present several cases of Mn accumulation in\\u000a the brain due to acquired or congenital diseases of the abdomen including hepatic cirrhosis with a portosystemic shunt, congenital\\u000a biliary atresia,

A. Uchino; T. Noguchi; K. Nomiyama; Y. Takase; T. Nakazono; J. Nojiri; S. Kudo

2007-01-01

417

Electrochemical lithium intercalation in disordered manganese oxides  

Microsoft Academic Search

Four highly disordered manganese oxides were prepared by reduction of sodium permanganate by chloride, iodide, hydrogen peroxide or oxalate in aqueous medium containing a large excess of Li+ ions, yielding hydrated oxides with Mn valence in the range 3.80–3.92. Thermogravimetric studies showed that the iodide-reduced oxide can be dehydrated to 92% at 240°C, while the other three ones retain water

A Ibarra Palos; M Anne; P Strobel

2001-01-01

418

Manganese olivine II: point defect relaxation  

Microsoft Academic Search

To investigate the point defect chemistry and the kinetic properties of manganese olivine Mn2SiO4, the point defect relaxation time (tau) characterizing the rate of re-equilibration of electrical conductivity following a change in oxygen fugacity was measured for single crystals oriented for electrical conduction along the [010] direction. The experiments were carried out at temperatures T = 1173-1473 K and oxygen

Q. Bai; Z.-C. Wang; D. L. Kohlstedt

1998-01-01

419

Manganese olivine II: point defect relaxation  

Microsoft Academic Search

To investigate the point defect chemistry and the kinetic properties of manganese olivine Mn2SiO4, the point defect relaxation time (?) characterizing the rate of re-equilibration of electrical conductivity following a\\u000a change in oxygen fugacity was measured for single crystals oriented for electrical conduction along the [010] direction. The\\u000a experiments were carried out at temperatures T?=?1173–1473?K and oxygen fugacities with the

Q. Bai; Z.-C. Wang; D. L. Kohlstedt

1998-01-01

420

The cosmic origin of carbon and manganese  

E-print Network

[ABRIDGED] We have determined carbon abundances for 51 dwarf stars and manganese abundances for 95 dwarf stars in two distinct and well defined stellar populations - the Galactic thin and thick disks. As these two populations have different chemical histories we have been able to, through a differential abundance analysis using high-resolution spectra, constrain the formation sites for carbon and manganese in the Galactic disk(s). The analysis of carbon is based on the forbidden [C I] line at 872.7 nm which is an abundance indicator that is insensitive to errors in the stellar atmosphere parameters. Combining these data with our previously published oxygen abundances, based on the forbidden [O I] line at 630.0 nm, we can form very robust [C/O] ratios that we then used to investigate the origin of carbon and the chemical evolution of the Galactic thin and thick disks..... Our interpretation of our abundance trends is that the sources that are responsible for the carbon enrichment in the Galactic thin and thick disks have operated on a time-scale very similar to those that are responsible for the Fe and Y enrichment (i.e., SNIa and AGB stars, respectively). For manganese, when comparing our Mn abundances with O abundances for the same stars we find that the abundance trends in the stars with kinematics typical of the thick disk can be explained by metallicity dependent yields from SN II. Furthermore, the [Mn/O] versus [O/H] trend in the halo is flat. We conclude that the simplest interpretation of our data is that manganese most likely is produced in SN II and that the Mn yields for such SNae must be metallicity dependent.

Thomas Bensby; Sofia Feltzing

2008-09-24

421

Strain Hardening of Hadfield Manganese Steel  

Microsoft Academic Search

The plastic flow behavior of Hadfield manganese steel in uniaxial tension and compression is shown to be greatly influenced\\u000a by transformation plasticity phenomena. Changes in the stress-strain (???) curves with temperature correlate with the observed\\u000a extent of deformation twinning, consistent with a softening effect of twinning as a deformation mechanism and a hardening\\u000a effect of the twinned microstructure. The combined

P. H. Adler; G. B. Olson; W. S. Owen

1986-01-01

422

Precision Nanoparticles  

SciTech Connect

A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

John Hemminger

2009-07-21

423

Precision Nanoparticles  

ScienceCinema

A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

John Hemminger

2010-01-08

424

78 FR 54269 - Electrolytic Manganese Dioxide From Australia and China; Institution of Five-Year Reviews  

Federal Register 2010, 2011, 2012, 2013

...Electrolytic Manganese Dioxide From Australia and China; Institution of Five-Year...on electrolytic manganese dioxide from Australia and China would be likely to lead to...of electrolytic manganese dioxide from Australia and China (73 FR 58537-58539)....

2013-09-03

425

40 CFR 424.60 - Applicability; description of the electrolytic manganese products subcategory.  

Code of Federal Regulations, 2013 CFR

...Applicability; description of the electrolytic manganese products subcategory. 424.60 Section...POINT SOURCE CATEGORY Electrolytic Manganese Products Subcategory § 424.60 ...Applicability; description of the electrolytic manganese products subcategory. The...

2013-07-01

426

40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Cobalt iron manganese oxide, carboxylic acid-modified...Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid-modified...identified generically as cobalt iron manganese oxide, carboxylic...

2013-07-01

427

40 CFR 424.60 - Applicability; description of the electrolytic manganese products subcategory.  

...Applicability; description of the electrolytic manganese products subcategory. 424.60 Section...POINT SOURCE CATEGORY Electrolytic Manganese Products Subcategory § 424.60 ...Applicability; description of the electrolytic manganese products subcategory. The...

2014-07-01

428

40 CFR 424.60 - Applicability; description of the electrolytic manganese products subcategory.  

Code of Federal Regulations, 2011 CFR

...Applicability; description of the electrolytic manganese products subcategory. 424.60 Section...POINT SOURCE CATEGORY Electrolytic Manganese Products Subcategory § 424.60 ...Applicability; description of the electrolytic manganese products subcategory. The...

2011-07-01

429

40 CFR 424.60 - Applicability; description of the electrolytic manganese products subcategory.  

Code of Federal Regulations, 2012 CFR

...Applicability; description of the electrolytic manganese products subcategory. 424.60 Section...POINT SOURCE CATEGORY Electrolytic Manganese Products Subcategory § 424.60 ...Applicability; description of the electrolytic manganese products subcategory. The...

2012-07-01

430

40 CFR 424.60 - Applicability; description of the electrolytic manganese products subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the electrolytic manganese products subcategory. 424.60 Section...POINT SOURCE CATEGORY Electrolytic Manganese Products Subcategory § 424.60 ...Applicability; description of the electrolytic manganese products subcategory. The...

2010-07-01

431

40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).  

... 2014-07-01 false Cobalt iron manganese oxide, carboxylic acid-modified...Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid-modified...identified generically as cobalt iron manganese oxide, carboxylic...

2014-07-01

432

Manganese toxicity to chlorophyll synthesis in tobacco callus. [Nicotiana tabacum  

SciTech Connect

Tobacco (Nicotiana tabacum) pith explants were grown on manganese containing medium. At moderate concentration (10 millimolar), manganese selectivity inhibited chlorophyll synthesis, resulting initially in growth of white callus. Several weeks later the white callus turned brown due to the accumulation of a pigment identified as protoporphyrin IX by its elution profile using high performance liquid chromatography, by its absorption spectrum, and by its fluorescence properties. At a concentration of 100 millimolar manganese the pigment accumulated without growth of the explant.

Clairmont, K.B.; Hagar, W.G.; Davis, E.A.

1986-01-01

433

Maternal Blood Manganese Levels and Infant Birth Weight  

PubMed Central

Background Manganese is both an essential element and a known neurotoxicant to children. High manganese exposures have been associated with negative reproductive outcomes in animals, but few epidemiologic studies have examined the effects of human fetal manganese exposure. Methods We studied the association between maternal and umbilical cord blood manganese levels and birth weight in a cohort of 470 mother-infant pairs born at term (?37 weeks gestation) in Ottawa County, Oklahoma. Nonlinear spline and quadratic regression models were used to test the hypothesis of an inverted U-shaped relationship between manganese levels and birth weight. Results Mean (standard deviation) concentration of manganese was 2.4 (0.95) ?g/dL in the maternal blood and 4.2 (1.6) ?g/dL in the cord blood. Umbilical cord manganese was not associated with birth weight. A nonlinear relationship was observed between maternal manganese and birth weight after adjusting for potential confounders. Birth weight increased with manganese levels up to 3.1 ?g/L, and then a slight reduction in weight was observed at higher levels. Compared with the 3.1-?g/L point of inflection, birth weight estimates at the 5th (1.3 ?g/L) and 95th (4.0 ?g/L) percentiles of exposure were ?160 g (95% confidence interval = ?286 to ?33) and ?46 g (?38 to 131), respectively. Conclusions Maternal blood manganese levels during pregnancy are associated with birth weight in a nonlinear pattern in full-term infants. These findings suggest that manganese may affect fetal growth. Possible detrimental effects of elevated manganese levels on the fetus should be further examined in more highly exposed populations. PMID:19289966

Zota, Ami R.; Ettinger, Adrienne S.; Bouchard, Maryse; Amarasiriwardena, Chitra J.; Schwartz, Joel; Hu, Howard; Wright, Robert O.

2011-01-01

434

Colloidal Manganese Oxide Precursor to Octahedral Layered, OL-3 Materials  

Microsoft Academic Search

We report the one-pot synthesis of a hexagonal form of a layered manganese oxide material (OL-3) using mild conditions and\\u000a low temperature. The oxidation of an aqueous solution of manganese acetate using tetramethylammonium hydroxide and hydrogen\\u000a peroxide at 4 °C leads to the formation of a colloidal manganese dioxide solution. Colloidal MnO2 was then flocculated using K ions, forming disordered layered

Jason P. Durand; Josanlet C. Villegas; Sinue Gomez-Mower; Oscar Giraldo; Steven L. Suib

2007-01-01

435

Manganese in Texas Soils and its Relation to Crops.  

E-print Network

on the weight of the crops can be seen by comparing the weights of the crops grown on the portions of soil which received no addition, with the weights of the crops grown on the portions which received manganese sulfate (Mn) and also the crops that received... ....................... Manganese (Mn). .................. Average ....................... Nitrogen, phosphoric acid, potash (NDK) I Average ..................... Nitrogen, phosphoric acid, potash and manganese (NDKMn) / Average ..................... Miller clay, 0...

Carlyle, E. C. (Elmer Cardinal)

1931-01-01

436

Manganese oxide nanowires, films, and membranes and methods of making  

DOEpatents

Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves and methods of making the same are disclosed. A method for forming nanowires includes hydrothermally treating a chemical precursor composition in a hydrothermal treating solvent to form the nanowires, wherein the chemical precursor composition comprises a source of manganese cations and a source of counter cations, and wherein the nanowires comprise ordered porous manganese ox