Sample records for manganese ferrite nanoparticles

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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).

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

    PubMed Central

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

    2014-01-01

    Magnetic nanoparticles (MNPs) have been used for various biomedical applications. Importantly, manganese ferrite-based nanoparticles have useful magnetic resonance imaging characteristics and potential for hyperthermia treatment, but their effects in the cardiovascular system are poorly reported. Thus, the objectives of this study were to determine the cardiovascular effects of three different types of manganese ferrite-based magnetic nanoparticles: citrate-coated (CiMNPs); tripolyphosphate-coated (PhMNPs); and bare magnetic nanoparticles (BaMNPs). The samples were characterized by vibrating sample magnetometer, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. The direct effects of the MNPs on cardiac contractility were evaluated in isolated perfused rat hearts. The CiMNPs, but not PhMNPs and BaMNPs, induced a transient decrease in the left ventricular end-systolic pressure. The PhMNPs and BaMNPs, but not CiMNPs, induced an increase in left ventricular end-diastolic pressure, which resulted in a decrease in a left ventricular end developed pressure. Indeed, PhMNPs and BaMNPs also caused a decrease in the maximal rate of left ventricular pressure rise (+dP/dt) and maximal rate of left ventricular pressure decline (?dP/dt). The three MNPs studied induced an increase in the perfusion pressure of isolated hearts. BaMNPs, but not PhMNPs or CiMNPs, induced a slight vasorelaxant effect in the isolated aortic rings. None of the MNPs were able to change heart rate or arterial blood pressure in conscious rats. In summary, although the MNPs were able to induce effects ex vivo, no significant changes were observed in vivo. Thus, given the proper dosages, these MNPs should be considered for possible therapeutic applications. PMID:25031535

  3. Manganese ferrite nanoparticle micellar nanocomposites as MRI contrast agent for liver imaging

    Microsoft Academic Search

    Jian Lu; Shuli Ma; Jiayu Sun; Chunchao Xia; Chen Liu; Zhiyong Wang; Xuna Zhao; Fabao Gao; Qiyong Gong; Bin Song; Xintao Shuai; Hua Ai; Zhongwei Gu

    2009-01-01

    Iron oxide nanoparticles are effective contrast agents for enhancement of magnetic resonance imaging at tissue, cellular or even molecular levels. In this study, manganese doped superparamagnetic iron oxide (Mn-SPIO) nanoparticles were used to form ultrasensitive MRI contrast agents for liver imaging. Hydrophobic Mn-SPIO nanoparticles are synthesized in organic phase and then transferred into water with the help of block copolymer

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  5. Long-circulating PEGylated manganese ferrite nanoparticles for MRI-based molecular imaging

    NASA Astrophysics Data System (ADS)

    Pernia Leal, Manuel; Rivera-Fernández, Sara; Franco, Jaime M.; Pozo, David; de La Fuente, Jesús M.; García-Martín, María Luisa

    2015-01-01

    Magnetic resonance based molecular imaging has emerged as a very promising technique for early detection and treatment of a wide variety of diseases, including cancer, neurodegenerative disorders, and vascular diseases. The limited sensitivity and specificity of conventional MRI are being overcome by the development of a new generation of contrast agents, using nanotechnology approaches, with improved magnetic and biological properties. In particular, for molecular imaging, high specificity, high sensitivity, and long blood circulation times are required. Furthermore, the lack of toxicity and immunogenicity together with low-cost scalable production are also necessary to get them into the clinics. In this work, we describe a facile, robust and cost-effective ligand-exchange method to synthesize dual T1 and T2 MRI contrast agents with long circulation times. These contrast agents are based on manganese ferrite nanoparticles (MNPs) between 6 and 14 nm in size covered by a 3 kDa polyethylene glycol (PEG) shell that leads to a great stability in aqueous media with high crystallinity and magnetization values, thus retaining the magnetic properties of the uncovered MNPs. Moreover, the PEGylated MNPs have shown different relaxivities depending on their size and the magnetic field applied. Thus, the 6 nm PEGylated MNPs are characterized by a low r2/r1 ratio of 4.9 at 1.5 T, hence resulting in good dual T1 and T2 contrast agents under low magnetic fields, whereas the 14 nm MNPs behave as excellent T2 contrast agents under high magnetic fields (r2 = 335.6 mM-1 s-1). The polymer core shell of the PEGylated MNPs minimizes their cytotoxicity, and allows long blood circulation times. This combination of cellular compatibility and excellent T2 and r2/r1 values under low magnetic fields, together with long circulation times, make these nanomaterials very promising contrast agents for molecular imaging.Magnetic resonance based molecular imaging has emerged as a very promising technique for early detection and treatment of a wide variety of diseases, including cancer, neurodegenerative disorders, and vascular diseases. The limited sensitivity and specificity of conventional MRI are being overcome by the development of a new generation of contrast agents, using nanotechnology approaches, with improved magnetic and biological properties. In particular, for molecular imaging, high specificity, high sensitivity, and long blood circulation times are required. Furthermore, the lack of toxicity and immunogenicity together with low-cost scalable production are also necessary to get them into the clinics. In this work, we describe a facile, robust and cost-effective ligand-exchange method to synthesize dual T1 and T2 MRI contrast agents with long circulation times. These contrast agents are based on manganese ferrite nanoparticles (MNPs) between 6 and 14 nm in size covered by a 3 kDa polyethylene glycol (PEG) shell that leads to a great stability in aqueous media with high crystallinity and magnetization values, thus retaining the magnetic properties of the uncovered MNPs. Moreover, the PEGylated MNPs have shown different relaxivities depending on their size and the magnetic field applied. Thus, the 6 nm PEGylated MNPs are characterized by a low r2/r1 ratio of 4.9 at 1.5 T, hence resulting in good dual T1 and T2 contrast agents under low magnetic fields, whereas the 14 nm MNPs behave as excellent T2 contrast agents under high magnetic fields (r2 = 335.6 mM-1 s-1). The polymer core shell of the PEGylated MNPs minimizes their cytotoxicity, and allows long blood circulation times. This combination of cellular compatibility and excellent T2 and r2/r1 values under low magnetic fields, together with long circulation times, make these nanomaterials very promising contrast agents for molecular imaging. Electronic supplementary information (ESI) available: Additional experimental details including TEM images of MNPs, size distribution graphs, thermogravimetric curves, FTIR spectra, and XRD patterns of MNPs. See DOI: 10.1039/c4nr05781c

  6. Effect of particle size on structural, magnetic and dielectric properties of manganese substituted nickel ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Kumar, E. Ranjith; Kamzin, Aleksandr S.

    2015-03-01

    Mn substituted NiFe2O4 ferrite nanoparticles (Mn-NiFe2O4) were synthesized by the auto-combustion method. Their actions were carried out at different fuel ratios (50%, 75% and 100%). The nanoparticles have been investigated by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. The average crystallite size of the synthesized and annealed samples was between 25 and 75 nm, which were found to be dependent on both fuel ratio and annealing temperatures. However, lattice parameters, interplanar spacing and grain size were controlled by varying the fuel ratio. Magnetic characterizations of the nanoparticles were carried out using a vibrating sample magnetometer at room temperature. The saturation magnetization was computed and found to lie between 6 emu/g and 57 emu/g depending on the particle size of the studied sample. The coercivity was found to exhibit non-monotonic behavior with the particle size. Such behavior can be accounted for by the combination between surface anisotropy and thermal energies. The value of dielectric constant and dielectric loss was found to exhibit almost linear dependence on the particle size.

  7. Relaxivities of hydrogen protons in aqueous solutions of PEG-coated rod-shaped manganese-nickel-ferrite (Mn0.4Ni0.6Fe2O4) nanoparticles

    NASA Astrophysics Data System (ADS)

    Iqbal, Yousaf; Bae, Hongsub; Rhee, Ilsu; Hong, Sungwook

    2014-11-01

    Spinel-structured manganese (Mn)-nickel (Ni)-ferrite nanoparticles were synthesized using a chemical co-precipitation method. Coating with PEG (polyethylene glycol) was simultaneously conducted along with the synthesis of Mn-Ni-ferrites. The X-ray diffraction (XRD) and the Fourier-transform infrared (FTIR) analyses revealed a cubic spinel ferrite structure of the synthesized nanoparticles. Transmission electron microscopy (TEM) images showed that the synthesized nanoparticles were rod-shaped with a uniform size distribution and that the average length and width were 15.13 ± 1.32 nm and 3.78 ± 0.71 nm, respectively. The bonding status of PEG on the nanoparticle surface was checked by using FTIR. The relaxivities of the hydrogen protons in the aqueous solutions of the coated particles were determined by using nuclear magnetic resonance (NMR) spectrometry. The T1 and the T2 relaxivities were 0.34 ± 0.11 mM-1s-1 and 29.91 ± 0.98 mM-1s-1, respectively. This indicates that the synthesized PEG-coated Mn-Ni-ferrite nanoparticles are suitable for use as T2 contrast agents.

  8. 40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...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...

  9. 40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...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...

  10. 40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...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...

  11. 40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...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...

  12. 40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...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...

  13. 40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...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...

  14. 40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 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...

  15. 40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...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...

  16. Structure and magnetic properties of manganese-zinc-ferrites prepared by spray pyrolysis method

    NASA Astrophysics Data System (ADS)

    Kotsikau, Dzmitry; Ivanovskaya, Maria; Pankov, Vladimir; Fedotova, Yulia

    2015-01-01

    A spray pyrolysis of a water solution of iron, manganese and iron nitrates is applied to prepare Zn0.5Mn0.5Fe2O4 single-phase ferrite with a spinel-type structure. The samples are characterized by means of differential scanning calorimetry, scanning and transmission electron microscopy, X-ray diffraction, infrared and 57Fe Mössbauer spectroscopy. The mass magnetization ? and the magnetic susceptibility 1/? of the ferrites are measured as a function of temperature over the range of 78-728 K. The obtained sample contains nanoparticles with an average diameter d ?7 nm possessing MnxZnyFe3-(x+y)O4 spinel-type structure with a uniform distribution of manganese and zinc atoms over the ferrite lattice. The Curie temperature is determined to be 375 ÷ 380 K.

  17. Nanostructured cobalt manganese ferrite thin films for gas sensor application

    Microsoft Academic Search

    Izabela Sandu; Lionel Presmanes; Pierre Alphonse; Philippe Tailhades

    2006-01-01

    Ferrite compounds are very important because of their optical, electrical or magnetic properties. Moreover, many papers relate to their development as possible gas sensor.In this study, we were interested in using cobalt–manganese–ferrite as sensitive layer for CO2 sensor devices. Such an application required a high surface activity, and consequently a small crystallite size and a large surface area. The physical

  18. Influence of manganese doping in multiferroic bismuth ferrite thin films

    Microsoft Academic Search

    Kouhei Takahashi; Masayoshi Tonouchi

    2007-01-01

    We have examined the influence of manganese doping to the magnetic properties of manganese-doped bismuth ferrite [BiFe1?xMnxO3 (x=0, 0.05, and 0.2)] thin films grown epitaxially on (LaAlO3)0.3(Sr2AlTaO6)0.7 substrates by pulsed laser deposition technique. Manganese doping gave rise to a gradual increase of spontaneous magnetization along with the clarity of magnetic hysteresis. This enhanced magnetization can be understood by the modification

  19. Aqueous ferrofluids based on manganese and cobalt ferrites

    Microsoft Academic Search

    Francisco Augusto Tourinho; Raymonde Franck; René Massart

    1990-01-01

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

  20. Ferrite Nanoparticles in Pharmacological Modulation of Angiogenesis

    NASA Astrophysics Data System (ADS)

    Deshmukh, Aparna; Radha, S.; Khan, Y.; Tilak, Priya

    2011-07-01

    Nanoparticles are being explored in the targeted drug delivery of pharmacological agents : angiogenesis being one such novel application which involves formation of new blood vessels or branching of existing ones. The present study involves the use of ferrite nanoparticles for precise therapeutic modulation of angiogenesis. The ferrite nanoparticles synthesized by co-precipitation of ferrous and ferric salts by a suitable base, were found to be 10-20 nm from X-ray diffraction and TEM measurements. The magnetization measurements showed superparamagnetic behavior of the uncoated nanoparticles. These ferrite nanoparticles were found to be bio-compatible with lymphocytes and neural cell lines from the biochemical assays. The chick chorioallantoic membrane(CAM) from the shell of fertile white Leghorn eggs was chosen as a model to study angiogenic activity. An enhancement in the angiogenic activity in the CAM due to addition of uncoated ferrite nanoparticles was observed.

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

    SciTech Connect

    Manigandan, R.; Suresh, R.; Giribabu, K.; Narayanan, V., E-mail: vnnara@yahoo.co.in [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600 025 (India); Vijayalakshmi, L. [Annai Veilankanni's College for Women (Arts and Science), Saidapet, Chennai 600015 (India); Stephen, A. [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2014-01-28

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  3. Studies on the activation energy from the ac conductivity measurements of rubber ferrite composites containing manganese zinc ferrite

    NASA Astrophysics Data System (ADS)

    Hashim, Mohd.; Alimuddin; Kumar, Shalendra; Shirsath, Sagar E.; Mohammed, E. M.; Chung, Hanshik; Kumar, Ravi

    2012-11-01

    Manganese zinc ferrites (MZF) have resistivities between 0.01 and 10 ? m. Making composite materials of ferrites with either natural rubber or plastics will modify the electrical properties of ferrites. The moldability and flexibility of these composites find wide use in industrial and other scientific applications. Mixed ferrites belonging to the series Mn(1-x)ZnxFe2O4 were synthesized for different ‘x’ values in steps of 0.2, and incorporated in natural rubber matrix (RFC). From the dielectric measurements of the ceramic manganese zinc ferrite and rubber ferrite composites, ac conductivity and activation energy were evaluated. A program was developed with the aid of the LabVIEW package to automate the measurements. The ac conductivity of RFC was then correlated with that of the magnetic filler and matrix by a mixture equation which helps to tailor properties of these composites.

  4. Magnetic properties of manganese ferrites with additions of oxides of rare-earth elements

    Microsoft Academic Search

    I. N. Frantsevich; A. I. Gunchenko; L. N. Tul'chinskii

    1964-01-01

    1.The authors studied the effect of admixtures of oxides of ytrrium, lanthanum, cerium, neodymium on the magnetic properties of manganese ferrites. It is shown that this effect is not the same for various rare earth oxides, depending on their content in the ferrite and the change in its structure.2.On the basis of the experimental data obtained preliminary conclusions were drawn

  5. MAGNETIC PROPERTIES OF MANGANESE FERRITES WITH ADDITIONS OF OXIDES OF RARE EARTH ELEMENTS. (COMMUNICATION I)

    Microsoft Academic Search

    I. N. Frantsevich; A. I. Gunchenko; L. N. Tulchinskii

    1962-01-01

    The effect of admixtures of oxides of Y,. La, Ce, and Nd on the ; magnetic propenties of manganese ferrites was studied. It is shown that the ; effect is not the same for various rare-earth oxides, depending on their content ; in the ferrite and the change in its structure. On the basis of the experimental ; data obtained,

  6. Ferrite nanoparticles for future heart diagnostics

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  7. Magnetic properties and adsorptive performance of manganese-zinc ferrites/activated carbon nanocomposites

    NASA Astrophysics Data System (ADS)

    Zhang, B. B.; Xu, J. C.; Xin, P. H.; Han, Y. B.; Hong, B.; Jin, H. X.; Jin, D. F.; Peng, X. L.; Li, J.; Gong, J.; Ge, H. L.; Zhu, Z. W.; Wang, X. Q.

    2015-01-01

    Owing to the unique microstructure and high specific surface area, activated carbon (AC) could act as an excellent adsorbent for wastewater treatment and good carrier for functional materials. In this paper, manganese-zinc ferrites (Mn0.5Zn0.5Fe2O4: MZF) were anchored into AC by hydrothermal method, resulting in the excellent magnetic response for AC nanocomposites in wastewater treatment. All results demonstrated the magnetic nanoparticles presented a spinel phase structure and existed in the pores of AC. The saturation magnetization (Ms) of MZF/AC nanocomposites increased with the ferrites content, while the pore volume and specific surface area declined. The Sample-5 possessed the specific surface area of 1129 m2 g-1 (close to 1243 m2 g-1 of AC) and Ms of 3.96 emu g-1. Furthermore, the adsorptive performance for organic dyes was studied and 99% methylene blue was adsorbed in 30 min. The magnetic AC nanocomposites could be separated easily from solution by magnetic separation technique.

  8. Fabrication of Mn-ferrite nanoparticles from MnO colloids.

    PubMed

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

    2009-11-28

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

  9. Optimizing hysteretic power loss of magnetic ferrite nanoparticles

    E-print Network

    Chen, Ritchie

    2013-01-01

    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 ...

  10. Friction and wear of single-crystal manganese-zinc ferrite

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1979-01-01

    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 line type) 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 are observed on the ferrite surfaces as a result of sliding.

  11. Friction and wear of single-crystal manganese-zinc ferrite

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1979-01-01

    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.

  12. Transition metal-substituted cobalt ferrite nanoparticles for biomedical applications.

    PubMed

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

    2013-03-01

    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

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

    PubMed

    Pickles, C A

    2010-07-15

    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

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

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1978-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

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

  16. Preparation of Nanoparticles of Barium Ferrite from Precipitation in Microemulsions

    Microsoft Academic Search

    B. J. Palla; D. O. Shah; P. Garcia-Casillas; J. Matutes-Aquino

    1999-01-01

    Magnetic nanoparticles of barium ferrite (BaFe12O19) have been synthesized using a microemulsion mediated process. The aqueous cores of water-in-oil microemulsions were used as constrained microreactors for the precipitation of precursor carbonate and hydroxide particles. These precursors were then calcined at 925°C for 12?h, during which time they were transformed to the hexagonal ferrite. The pH of reaction was varied between

  17. The role of cobalt ferrite magnetic nanoparticles in medical science.

    PubMed

    Amiri, S; Shokrollahi, H

    2013-01-01

    The nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nano-electronics, environmental remediation and medical healthcare. In this area, cobalt ferrite nanoparticles have been regarded as one of the competitive candidates because of their suitable physical, chemical and magnetic properties like the high anisotropy constant, high coercivity and high Curie temperature, moderate saturation magnetization and ease of synthesis. This paper introduces the magnetic properties, synthesis methods and some medical applications, including the hyperthermia, magnetic resonance imaging (MRI), magnetic separation and drug delivery of cobalt ferrite nanoparticles. PMID:25428034

  18. Study of DNA interaction with cobalt ferrite nanoparticles.

    PubMed

    Pershina, A G; Sazonov, A E; Novikov, D V; Knyazev, A S; Izaak, T I; Itin, V I; Naiden, E P; Magaeva, A A; Terechova, O G

    2011-03-01

    Interaction of cobalt ferrite nanopowder and nucleic acid was investigated. Superparamagnetic cobalt ferrite nanoparticles (6-12 nm) were prepared by mechanochemical synthesis. Structure of the nanopowder was characterized using X-ray diffraction. It was shown that cobalt ferrite nanoparticles were associated with ssDNA and dsDNA in Tris-buffer resulting in bionanocomposite formation with mass weight relation nanoparticles: DNA 1:(0.083 +/- 0.003) and 1:(0.075 +/- 0.003) respectively. The mechanism of interaction between a DNA and cobalt ferrite nanoparticles was considered basing on the whole set of obtained data: FTIR-spectroscopy, analyzing desorption of DNA from the surface of the particles while changing the chemical content of the medium, and on the modeling interaction of specific biomolecule fragments with surface of a inorganic material. It was supposed that the linkage was based on coordination interaction of the phosphate groups and oxygen atoms heterocyclic bases of DNA with metal ions on the particle surface. These data can be used to design specific magnetic DNA-nanoparticles hybrid structures. PMID:21449452

  19. Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles

    Microsoft Academic Search

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

    2011-01-01

    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

  20. Magnetic, electric and thermal properties of cobalt ferrite nanoparticles , N. Mlikia

    E-print Network

    Paris-Sud XI, Université de

    1 Magnetic, electric and thermal properties of cobalt ferrite nanoparticles L.Ajroudia , N. Mlikia]. The elaboration route developed led to chemically homogeneous spinel cobalt ferrites, with mean size ranging from. The sensing properties of cobalt ferrite nanoparticles were investigated, and different resistance variations

  1. Synthesis and microstructure of cobalt ferrite nanoparticles L.Ajroudi1,2

    E-print Network

    Paris-Sud XI, Université de

    1 Synthesis and microstructure of cobalt ferrite nanoparticles L.Ajroudi1,2 , S.Villain1 , V Tunis, Tunisia Abstract Cobalt ferrites (CoxFe3-xO4) nanoparticles with various compositions were synthesized by a new non-aqueous synthesis method. The cobalt ferrites were characterized by X

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

    PubMed

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

    2012-05-01

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

  3. Strong and moldable cellulose magnets with high ferrite nanoparticle content.

    PubMed

    Galland, Sylvain; Andersson, Richard L; Ström, Valter; Olsson, Richard T; Berglund, Lars A

    2014-11-26

    A major limitation in the development of highly functional hybrid nanocomposites is brittleness and low tensile strength at high inorganic nanoparticle content. Herein, cellulose nanofibers were extracted from wood and individually decorated with cobalt-ferrite nanoparticles and then for the first time molded at low temperature (<120 °C) into magnetic nanocomposites with up to 93 wt % inorganic content. The material structure was characterized by TEM and FE-SEM and mechanically tested as compression molded samples. The obtained porous magnetic sheets were further impregnated with a thermosetting epoxy resin, which improved the load-bearing functions of ferrite and cellulose material. A nanocomposite with 70 wt % ferrite, 20 wt % cellulose nanofibers, and 10 wt % epoxy showed a modulus of 12.6 GPa, a tensile strength of 97 MPa, and a strain at failure of ca. 4%. Magnetic characterization was performed in a vibrating sample magnetometer, which showed that the coercivity was unaffected and that the saturation magnetization was in proportion with the ferrite content. The used ferrite, CoFe2O4, is a magnetically hard material, demonstrated by that the composite material behaved as a traditional permanent magnet. The presented processing route is easily adaptable to prepare millimeter-thick and moldable magnetic objects. This suggests that the processing method has the potential to be scaled-up for industrial use for the preparation of a new subcategory of magnetic, low-cost, and moldable objects based on cellulose nanofibers. PMID:25331121

  4. Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses

    PubMed Central

    Hetaba, Walid; Wißbrock, Marco; Löffler, Stefan; Mill, Nadine; Eckstädt, Katrin; Dreyer, Axel; Ennen, Inga; Sewald, Norbert; Schattschneider, Peter; Hütten, Andreas

    2014-01-01

    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

  5. Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses.

    PubMed

    Wolff, Annalena; Hetaba, Walid; Wißbrock, Marco; Löffler, Stefan; Mill, Nadine; Eckstädt, Katrin; Dreyer, Axel; Ennen, Inga; Sewald, Norbert; Schattschneider, Peter; Hütten, Andreas

    2014-01-01

    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

  6. Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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.

  7. Polyaspartic acid coated manganese oxide nanoparticles for efficient liver MRI

    NASA Astrophysics Data System (ADS)

    Xing, Ruijun; Zhang, Fan; Xie, Jin; Aronova, Maria; Zhang, Guofeng; Guo, Ning; Huang, Xinglu; Sun, Xiaolian; Liu, Gang; Bryant, L. Henry; Bhirde, Ashwinkumar; Liang, Amy; Hou, Yanglong; Leapman, Richard D.; Sun, Shouheng; Chen, Xiaoyuan

    2011-12-01

    We report in this communication a simple, facile surface modification strategy to transfer hydrophobic manganese oxide nanoparticles (MONPs) into water by using polyaspartic acid (PASP). We systematically investigated the effect of the size of PASP-MONPs on MRI of normal liver and found that the particles with a core size of 10 nm exhibited greater enhancement than those with larger core sizes.We report in this communication a simple, facile surface modification strategy to transfer hydrophobic manganese oxide nanoparticles (MONPs) into water by using polyaspartic acid (PASP). We systematically investigated the effect of the size of PASP-MONPs on MRI of normal liver and found that the particles with a core size of 10 nm exhibited greater enhancement than those with larger core sizes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr11242b

  8. Polyaspartic acid coated manganese oxide nanoparticles for efficient liver MRI.

    PubMed

    Xing, Ruijun; Zhang, Fan; Xie, Jin; Aronova, Maria; Zhang, Guofeng; Guo, Ning; Huang, Xinglu; Sun, Xiaolian; Liu, Gang; Bryant, L Henry; Bhirde, Ashwinkumar; Liang, Amy; Hou, Yanglong; Leapman, Richard D; Sun, Shouheng; Chen, Xiaoyuan

    2011-12-01

    We report in this communication a simple, facile surface modification strategy to transfer hydrophobic manganese oxide nanoparticles (MONPs) into water by using polyaspartic acid (PASP). We systematically investigated the effect of the size of PASP-MONPs on MRI of normal liver and found that the particles with a core size of 10 nm exhibited greater enhancement than those with larger core sizes. PMID:22064945

  9. Polyaspartic acid coated manganese oxide nanoparticles for efficient liver MRI†

    PubMed Central

    Xing, Ruijun; Zhang, Fan; Xie, Jin; Aronova, Maria; Zhang, Guofeng; Guo, Ning; Huang, Xinglu; Sun, Xiaolian; Liu, Gang; Bryant, L. Henry; Bhirde, Ashwinkumar; Liang, Amy; Hou, Yanglong; Leapman, Richard D.; Sun, Shouheng; Chen, Xiaoyuan

    2013-01-01

    We report in this communication a simple, facile surface modification strategy to transfer hydrophobic manganese oxide nanoparticles (MONPs) into water by using polyaspartic acid (PASP). We systematically investigated the effect of the size of PASP-MONPs on MRI of normal liver and found that the particles with a core size of 10 nm exhibited greater enhancement than those with larger core sizes. PMID:22064945

  10. JOURNAL DE PHYSIQUE Colloque C 1, supplbment au no 2-3, Tome 32, Fkvrier-Mars 1971,page C 1 -62 THE ULTRASONIC LOSS OF MANGANESE FERRITES (Mn,Fe, -,04)

    E-print Network

    Paris-Sud XI, Université de

    THE ULTRASONIC LOSS OF MANGANESE FERRITES (Mn,Fe, -,04) WITH A MANGANESE CONTENT BETWEEN 0.7 AND 1 ferrites de manganese MnzFes-z04 avec x compris entre 0,7 et 1,6. Un modele expliquant les r6sultats ultrasonic loss measurements were performed on manganese ferrites MnzFe3-z04for x between 0.7 and 1

  11. Magnetic properties of substituted strontium ferrite nanoparticles and thin films

    NASA Astrophysics Data System (ADS)

    Ghasemi, Ali

    2012-04-01

    SrFe12-x(Zr0.5Mg0.5)xO19 nanoparticles and thin films with x=0-2.5 were synthesized by a sol-gel method on thermally oxidized silicon wafer (Si/SiO2). Structural and magnetic characteristics of synthesized samples were studied employing x-rays diffraction (XRD), transmission electron microscopy (TEM), magnetic susceptometer, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). TEM micrographs display that the narrow size distribution of ferrite nanoparticles with average particle size of 50 nm were fabricated. Fitting obtained data of effective magnetic susceptibility by Vogel-Fulcher law confirms the existence of strong magnetic interaction among fine particles. XRD patterns and FE-SEM micrographs demonstrated that single phase c-axis hexagonal ferrite films with rather narrow grain size distribution were obtained. AFM micrographs exhibited that the surface roughness increases with an increase in Zr-Mg content. It was found from the VSM graphs that with an increase in substitution contents the coercivity decreases, while the saturation of magnetization increases. The Henkle plots confirms the existence of exchange coupling among nano-grain in ferrite thin films.

  12. Resistive switching properties of manganese oxide nanoparticles with hexagonal shape

    NASA Astrophysics Data System (ADS)

    Hu, Quanli; Park, Mira; Abbas, Yawar; Kim, Jai Soon; Yoon, Tae-Sik; Choi, Young Jin; Kang, Chi Jung

    2015-01-01

    Uniformly sized hexagonal shaped manganese oxide (MnO) nanoparticles were chemically synthesized. The bipolar resistive switching characteristics were investigated in the Ti/MnO/Pt structure. The nanoparticles were assembled as close-packed monolayer with a thickness of 30 nm by dip-coating and annealing procedures. The bipolar resistive switching behaviors in Ti/MnO/Pt device could be caused by the formation and rupture of conductive filaments in the nanoparticles. The temperature dependence of resistance was discussed. The resistance of HRS presented a negative temperature dependence at high temperature, indicating a typical semiconducting behavior. The resistance of LRS increased with the elevated temperature exhibiting a metallic state. Ohmic conduction, space charge limited conduction (SCLC), and Schottky conduction have been investigated for the conduction and switching mechanism.

  13. 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)

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

    2014-02-01

    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.

  14. Low-temperature calorimetric properties of zinc ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Ho, J. C.; Hamdeh, H. H.; Chen, Y. Y.; Lin, S. H.; Yao, Y. D.; Willey, R. J.; Oliver, S. A.

    1995-10-01

    Calorimetric measurements between 1 and 40 K by a thermal relaxation technique have been made on zinc ferrite nanoparticles prepared from an aerogel process. The expected ?-type heat-capacity peak near 10 K, which corresponds to a long-range antiferromagnetic transition in the bulk form of this material, is greatly suppressed. Broad peaks begin to prevail after the sample is annealed at 500 or 800 °C, but ball milling of the nanoparticles leads to almost complete disappearance of the low-temperature ordering. In all cases, calorimetrically based magnetic entropy at 40 K accounts for only a fraction of 2R ln(2S+1) with S=5/2 for Fe3+. These results are corroborated by magnetic data, which also indicate magnetic ordering at high temperatures. Such observations can be understood by considering the relative distribution of Fe3+ between two nonequivalent (A and B) sites in the spinel-type lattice. In particular, the as-prepared fine particles show large Fe3+ occupancy of the A sites, whereas these ions prefer the B sites in bulk zinc ferrite. Meanwhile, the lattice heat capacity is enhanced, yielding effective Debye temperatures of 225, 285, 345, and 360 K for the as-prepared, 500 °C-annealed, 800 °C-annealed, and ball milled sample, respectively, in contrast to 425 K for the bulk material.

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

    SciTech Connect

    Chaturvedi, Smita; Rajendra, Ranguwar; Ballav, Nirmalya; Kulkarni, Sulabha, E-mail: s.kulkarni@iiserpune.ac.in [Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008 (India); Sarkar, Indranil [DESY Photon Science, Deutsches Elektronen-Synchrotron, 22607 Hamburg (Germany); Shirolkar, Mandar M. [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Jeng, U-Ser; Yeh, Yi-Qi [National Synchrotron Radiation Research Center, 101, Hsin-Ann Road, Science Park, Hsinchu 3007-6, Taiwan (China)

    2014-09-08

    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 Fe{sup 3+} and Bi{sup 3+} 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 Bi{sup 0} 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Ramana, C. V.; Kolekar, Y. D.; Kamala Bharathi, K.; Sinha, B.; Ghosh, K.

    2013-11-01

    Manganese (Mn) substituted cobalt ferrites (CoFe2-xMnxO4, 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 CoFe2-xMnxO4 (x = 0.00-0.15) ferrites. The cubic anisotropy constant (K1(T)) and saturation magnetization (Ms(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 (Hc). Saturation magnetization (Ms), obtained from the model, decreases with increasing temperature. For CoFe2O4, Ms decreases from 3.63 ?B per formula unit (f.u.) to 3.47 ?B/f.u. with increasing temperature from 10 to 300 K. CFMO (0.00-0.15) exhibit the similar trend while the magnitude of Ms is dependent on Mn-concentration. Ms-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 ˜10-4 s and ˜0.35(±0.05), respectively.

  18. Tuning the thermal relaxation of transition-metal ferrite nanoparticles through their intrinsic magnetocrystalline anisotropy

    E-print Network

    Spinu, Leonard

    constant in barium ferrite BaFe12O19 J. Appl. Phys. 110, 096107 (2011) Positive exchange bias in asTuning the thermal relaxation of transition-metal ferrite nanoparticles through their intrinsic at finite temperatures J. Appl. Phys. 110, 103906 (2011) Magnetic anisotropy and coercivity of Fe3Se4

  19. Dielectric properties of cobalt ferrite nanoparticles in ultrathin nanocomposite films.

    PubMed

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

    2013-12-01

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

  20. Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles

    SciTech Connect

    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

    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.

  1. Maximizing Hysteretic Losses in Magnetic Ferrite Nanoparticles via Model-Driven Synthesis and Materials Optimization

    E-print Network

    Chen, Ritchie

    This article develops a set of design guidelines for maximizing heat dissipation characteristics of magnetic ferrite MFe[subscript 2]O[subscript 4] (M = Mn, Fe, Co) nanoparticles in alternating magnetic fields. Using ...

  2. Direct dyes removal using modified magnetic ferrite nanoparticle

    PubMed Central

    2014-01-01

    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

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

    SciTech Connect

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

    2008-08-04

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

  4. Cellular Uptake and Biocompatibility of Bismuth Ferrite Harmonic Advanced Nanoparticles

    E-print Network

    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

    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.

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

    SciTech Connect

    Seralessandri, L.; Bellusci, M.; Alvani, C.; La Barbera, A.; Padella, F. [ENEA-C.R. Casaccia, Italian National Agency for New Technologies, Energy and the Environment, Via Anguillarese 301, 00123 Roma (Italy); Varsano, F. [ENEA-C.R. Casaccia, Italian National Agency for New Technologies, Energy and the Environment, Via Anguillarese 301, 00123 Roma (Italy)], E-mail: francesca.varsano@casaccia.enea.it

    2008-08-15

    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{sub 2}O{sub 4}/Na{sub 2}CO{sub 3}/Na(Mn{sub 1/3}Fe{sub 2/3})O{sub 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{sub 1-x}Mn{sub 1/3}Fe{sub 2/3}O{sub 2-{delta}} phases were observed together with the expected MnFe{sub 2}O{sub 4}/Na{sub 2}CO{sub 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. - Graphical abstract: Na(Mn{sub 1/3}Fe{sub 2/3})O{sub 2} disproportion reaction in the presence of CO{sub 2} was studied. Chemical equilibria among Na{sub 1-x}(Mn{sub 1/3}Fe{sub 2/3})O{sub 2}, MnFe{sub 2}O{sub 4} and Na{sub 2}CO{sub 3} compounds were evidenced and studied by means of Rietveld analysis performed on XRD patterns. Two different sodium-depleted lamellar structures were identified. The role of sodium carbonate formation/dissociation equilibrium in the oxygen-releasing step of the manganese ferrite thermochemical cycle has been highlighted.

  6. The electrical properties of manganese ferrite powders prepared by two different methods

    NASA Astrophysics Data System (ADS)

    Lungu, A.; Malaescu, I.; Marin, C. N.; Vlazan, P.; Sfirloaga, P.

    2015-04-01

    Two powder samples of manganese ferrite (MnFe2O4) with different morphology and particle size 30-40 nm, denoted by A and B have been synthesized by different methods starting from MnCl2·4H2O and FeCl3·6H2O. Sample A was obtained by co-precipitation followed by calcination at 900 °C and sample B has been obtained by hydrothermal method. XRD analysis show that calcination leads to the occurrence of other phases than MnFe2O4, therefore the hydrothermal method gives better results. From the temperature dependence of the electrical resistivity, measured over the range 300-483 K, the activation energy, ?E, of the investigated samples has been evaluated, resulting in 0.43 eV (for sample A) and 0.32 eV (for sample B). The conductivity mechanism in the samples was explained in terms of Mott's variable range hopping (VRH) model. The results showed that the density of states at the Fermi level is constant over the investigated temperature range, being in order of 0.788 ×1017eV-1cm-3 (for sample A) and 2.05 ×1017eV-1cm-3 (for sample B). The hopping distance, R and the hopping energy, W (parameters of VRH model) have also been computed. Room temperature values are R=27.08 nm and W=152 meV for sample A and R=21.29 nm and W=120 meV for sample B.

  7. Dielectric relaxations and alternating current conductivity in manganese substituted cobalt ferrite

    SciTech Connect

    Kolekar, Y. D.; Sanchez, L. J.; Ramana, C. V., E-mail: rvchintalapalle@utep.edu [Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States)

    2014-04-14

    Manganese (Mn) substituted cobalt ferrites (CoFe{sub 2-x}Mn{sub x}O{sub 4}, referred to CFMO) have been synthesized by the solid state reaction method and their dielectric properties and ac conductivity have been evaluated as a function of applied frequency and temperature. X-ray diffraction measurements indicate that CFMO crystallize in the inverse cubic spinel phase with a lattice constant ?8.38?Å. Frequency dependent dielectric measurements at room temperature obey the modified Debye model with relaxation time of 10{sup ?4} s and spreading factor of 0.35(±0.05). The frequency (20?Hz–1?MHz) and temperature (T?=?300–900?K) dependent dielectric constant analyses indicate that CFMO exhibit two dielectric relaxations at lower frequencies (1–10?kHz), while completely single dielectric relaxation for higher frequencies (100?kHz–1?MHz). The dielectric constant of CFMO is T-independent up to ?400?K, at which point increasing trend prevails. The dielectric constant increase with T?>?400?K is explained through impedance spectroscopy assuming a two-layer model, where low-resistive grains separated from each other by high-resistive grain boundaries. Following this model, the two electrical responses in impedance formalism are attributed to the grain and grain-boundary effects, respectively, which also satisfactorily accounts for the two dielectric relaxations. The capacitance of the bulk of the grain determined from impedance analyses is ?10?pF, which remains constant with T, while the grain-boundary capacitance increases up to ?3.5 nF with increasing T. The tan ? (loss tangent)-T also reveals the typical behavior of relaxation losses in CFMO.

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

    PubMed

    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

    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

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

    PubMed Central

    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

    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

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

    PubMed

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

    2010-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  12. Polyvinyl alcohol functionalized cobalt ferrite nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Salunkhe, A. B.; Khot, V. M.; Thorat, N. D.; Phadatare, M. R.; Sathish, C. I.; Dhawale, D. S.; Pawar, S. H.

    2013-01-01

    In the present work, cobalt ferrite nanoparticles (CoFe2O4 NPs) have been synthesized by combustion method. The surface of the CoFe2O4 NPs was modified with biocompatible polyvinyl alcohol (PVA). To investigate effect and nature of coating on the surface of CoFe2O4 NPs, the NPs were characterized X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The transmission electron microscopy (TEM) and dynamic light scattering (DLS) results demonstrate the monodispersed characteristics of CoFe2O4 NPs after surface modification with PVA. The decrease in contact angle from 162° to 50° with PVA coating on NPs indicates the transition from hydrophobic nature to hydrophilic. The Magnetic properties measurement system (MPMS) results show that the NPs have ferromagnetic behavior with high magnetization of 75.04 and 71.02 emu/g of uncoated and coated CoFe2O4 NPs respectively. These PVA coated NPs exhibit less toxicity over uncoated CoFe2O4 NPs up to 1.8 mg mL-1 when tested with mouse fibroblast L929 cell line.

  13. Preparation and characterization of cobalt ferrite nanoparticles coated with fucan and oleic acid

    NASA Astrophysics Data System (ADS)

    Andrade, P. L.; Silva, V. A. J.; Maciel, J. C.; Santillan, M. M.; Moreno, N. O.; De Los Santos Valladares, L.; Bustamante, Angel; Pereira, S. M. B.; Silva, M. P. C.; Albino Aguiar, J.

    2014-01-01

    Cobalt ferrite has attracted considerable attention in recent years due to its unique physical properties such as high Curie temperature, large magnetocrystalline anisotropy, moderate saturation magnetization, large magnetostrictive coefficient, excellent chemical stability and mechanical hardness. In this work we present the preparation, of fucan coated cobalt ferrite nanoparticles by a modified co-precipitation method and the study of their structural, microstructural and magnetic characteristics for their application as a solid support for enzymes immobilization and other biotechnology applications. Aqueous suspensions of magnetic particles were prepared by coprecipitation of Fe(III) and Co(II) in the presence of NaOH, acid oleic and fucan polymer. The X-ray diffraction indicates that the funtionalization does not degrade the core cobalt ferrite. The infrared (FTIR) bands, indicate the functional characteristics of the coating on the cobalt ferrite. Mössbauer spectra at room temperature indicate the presence of a broadened sextet plus a doublet which is typical of superparamagnetic relaxation. For the Co-ferrite uncoated and coated with fucan the doublets have areas of 36.1 % and 40.3 % respectively, indicating the presence of non-interacting particles and faster relaxation time. The Co-ferrite coated with oleic acid and oleic acid plus fucan have areas around 17.5 % and 17.1 % respectively which indicate a weak superparamagnetic relaxation due to a slow relaxation time. The magnetization measurements of the cobalt ferrite nanoparticles with and without coating confirm that they are superparamagnetic and this behavior is produced by the core nanoparticles rather than the coatings. The cobalt ferrite nanoparticles coated with oleic acid presented the highest magnetization than when coating with fucan.

  14. Hyperthermia HeLa cell treatment with silica coated manganese oxide nanoparticles

    E-print Network

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

    2009-01-01

    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.

  15. Synthesis of shape controlled ferrite nanoparticles by sonochemical technique.

    PubMed

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

    2008-08-01

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

  16. Zinc ferrite nanoparticle as a magnetic catalyst: Synthesis and dye degradation

    SciTech Connect

    Mahmoodi, Niyaz Mohammad, E-mail: mahmoodi@icrc.ac.ir

    2013-10-15

    Graphical abstract: Photocatalytic degradation of Reactive Red 198 and Reactive Red 120 by the synthesized zinc ferrite nanoparticle. - Highlights: • Magnetic zinc ferrite nanoparticle was synthesized and characterized. • Photocatalytic dye degradation by magnetic nanoparticle was studied. • Formate, acetate and oxalate were detected as dominant dye degradation aliphatic intermediates. • Nitrate and sulfate ions were detected as mineralization products of dyes. • Zinc ferrite nanoparticle was an effective magnetic photocatalyst to degrade dyes. - Abstract: In this paper, magnetic zinc ferrite (ZnFe{sub 2}O{sub 4}) nanoparticle was synthesized and its photocatalytic dye degradation ability from colored wastewater was studied. Reactive Red 198 (RR198) and Reactive Red 120 (RR120) were used as model dyes. The characteristics of ZnFe{sub 2}O{sub 4} were investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). Photocatalytic dye degradation by ZnFe{sub 2}O{sub 4} was studied by UV–vis spectrophotometer and ion chromatography (IC). The effects of ZnFe{sub 2}O{sub 4} dosage, initial dye concentration and salt on dye degradation were evaluated. Formate, acetate and oxalate anions were detected as dominant aliphatic intermediate. Inorganic anions (nitrate and sulfate anions) were detected as dye mineralization products. The results indicated that ZnFe{sub 2}O{sub 4} could be used as a magnetic photocatalyst to degrade dyes from colored wastewater.

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

    PubMed Central

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

    2013-01-01

    The long-term objective of the present study was to determine the ability of NiZn ferrite nanoparticles to kill cancer cells. NiZn ferrite nanoparticle suspensions were found to have an average hydrodynamic diameter, polydispersity index, and zeta potential of 254.2 ± 29.8 nm, 0.524 ± 0.013, and ?60 ± 14 mV, respectively. We showed that NiZn ferrite nanoparticles had selective toxicity towards MCF-7, HepG2, and HT29 cells, with a lesser effect on normal MCF 10A cells. The quantity of Bcl-2, Bax, p53, and cytochrome C in the cell lines mentioned above was determined by colorimetric methods in order to clarify the mechanism of action of NiZn ferrite nanoparticles in the killing of cancer cells. Our results indicate that NiZn ferrite nanoparticles promote apoptosis in cancer cells via caspase-3 and caspase-9, downregulation of Bcl-2, and upregulation of Bax and p53, with cytochrome C translocation. There was a concomitant collapse of the mitochondrial membrane potential in these cancer cells when treated with NiZn ferrite nanoparticles. This study shows that NiZn ferrite nanoparticles induce glutathione depletion in cancer cells, which results in increased production of reactive oxygen species and eventually, death of cancer cells. PMID:24204141

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  19. Static and dynamic magnetic properties of Co 2 Z barium ferrite nanoparticle composites

    Microsoft Academic Search

    Z. W. Li; L. Chen; C. K. Ong; Z. Yang

    2005-01-01

    The static, dynamic and attenuation properties of Co2Z barium ferrites and Co2Z composites have been studied. The results showed that both static and dynamic magnetic properties are significantly different for large particles and nanoparticles. As compared to large particles, Co2Z nanoparticles have a small saturation magnetization Ms, large coercivity Hc, small permeability µ'0 and µ''max, but high resonance frequency fR.

  20. Domain size correlated magnetic properties and electrical impedance of size dependent nickel ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Kamble, Ramesh B.; Varade, Vaibhav; Ramesh, K. P.; Prasad, V.

    2015-01-01

    We report here the investigations on the size dependent variation of magnetic properties of nickel ferrite nanoparticles. Nickel ferrite nanoparticles of different sizes (14 to 22 nm) were prepared by the sol-gel route at different annealing temperatures. They are characterized by TGA-DTA, XRD, SEM, TEM and Raman spectroscopy techniques for the confirmation of the temperature of phase formation, thermal stability, crystallinity, morphology and structural status of the nickel ferrite nanoparticles. The magnetization studies revealed that the saturation magnetization (Ms), retentivity (Mr) increase, while coercivity (Hc) and anisotropy (Keff) decrease as the particle size increases. The observed value of Ms is found to be relatively higher for a particle size of 22 nm. In addition, we have estimated the magnetic domain size using magnetic data and correlated to the average particle size. The calculated magnetic domain size is closely matching with the particle size estimated from XRD. Impedance spectroscopy was employed to study the samples in an equivalent circuit to understand their transport phenomena. It shows that nickel ferrite nanoparticles exhibit a non-Debye behavior with increasing particle size due to the influence of increasing disorders, surface effects, grain size and grain boundaries, etc.

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

    SciTech Connect

    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

    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.

  2. SAXS study of hexagonal W-type barium ferrite nanoparticles

    Microsoft Academic Search

    A. Wacha; L. Trif; Z. Varga; G. Goerigk; A. B ´ ota; U. Vainio

    Hexagonal ferrites are a wide family of ferromagnetic oxides, with peculiar and useful properties. The crystal structure of the different known types of hexagonal ferrites (M, W, X, Y, Z and U) is very complex and can be considered as a superposition of R and S blocks along the hexagonal c axis, RSR*S*for M-typeand RSSR*S*S*forW-type, whereR is a three-oxygen-layerblock with

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

    PubMed

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

    2013-01-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

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

    SciTech Connect

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

    2011-11-15

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

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

    PubMed

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

    2013-10-22

    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

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

    SciTech Connect

    Hsiung, L; Fluss, M; Kimura, A

    2010-04-06

    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.

  9. Enhancement of electrical properties of manganese tungstate nanoparticles by beam irradiation

    NASA Astrophysics Data System (ADS)

    Aloysius Sabu, N.; Priyanka, K. P.; Sheena, X.; Mohammed, E. M.; Varghese, T.

    2015-02-01

    MnWO4 nanoparticles were synthesized using simple chemical precipitation method. The dielectric properties of irradiated and non-irradiated samples of monoclinic manganese tungstate nanoparticles have been studied as a function of frequency. It is found that electric properties such as dielectric constant, loss tangent and a.c. conductivity of the irradiated sample were much larger as compared to the non-irradiated sample, which has been attributed to defects and reduction in particle size caused by the beam irradiation. The present investigation observed that the electron beam irradiation is an efficient technique to modify the electrical properties of MnWO4 nanoparticles.

  10. Development of Manganese-Based Nanoparticles as Contrast Probes for Magnetic Resonance Imaging

    PubMed Central

    Zhen, Zipeng; Xie, Jin

    2012-01-01

    MRI is one of the most important imaging tools in clinics. It interrogates nuclei of atoms in a living subject, providing detailed delineation with high spatial and temporal resolutions. To compensate the innate low sensitivity, MRI contrast probes were developed and widely used. These are typically paramagnetic or superparamagnetic materials, functioning by reducing relaxation times of nearby protons. Previously, gadolinium(Gd)-based T1 contrast probes were dominantly used. However, it was found recently that their uses are occasionally associated with nephrogenic system fibrosis (NSF), which suggests a need of finding alternatives. Among the efforts, manganese-containing nanoparticles have attracted much attention. By careful engineering, manganese nanoparticles with comparable r1 relaxivities can be yielded. Moreover, other functionalities, be a targeting motif, a therapeutic agent or a second imaging component, can be loaded onto these nanoparticles, resulting in multifunctional nanoplatforms. PMID:22272218

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

    Microsoft Academic Search

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

    2007-01-01

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

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

    E-print Network

    Volinsky, Alex A.

    by the powder metallurgy (PM) methods. SMCs have unique magnetic properties, such as a three-dimen- sional (3DIron-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

  13. Manganese

    MedlinePLUS

    ... iron, zincTaking calcium along with any of these minerals can decrease the amount of manganese that the body can take in.IP-6 (Phytic acid)IP-6 found in foods, such as cereals, nuts, and beans, and in supplements can decrease the amount of ...

  14. Study of Zn-Cu Ferrite Nanoparticles for LPG Sensing

    PubMed Central

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

    2013-01-01

    Nanostructured zinc-copper mixed ferrite was synthesized using sol-gel method. XRD patterns of different compositions of zinc-copper ferrite, Zn(1?x)CuxFe2O4 (x = 0.0, 0.25, 0.50, 0.75), revealed single phase inverse spinel ferrite in all the samples synthesized. With increasing copper concentration, the crystallite size was found to be increased from 28?nm to 47?nm. The surface morphology of all the samples studied by the Scanning Electron Microscopy there exhibits porous structure of particles throughout the samples. The pellets of the samples are prepared for LPG sensing characteristics. The sensing is carried out at different operating temperatures (200, 225, and 250°C) with the variation of LPG concentrations (0.2, 0.4, and 0.6 vol%). The maximum sensitivity of 55.33% is observed at 250°C operating for the 0.6 vol% LPG. PMID:23864833

  15. Study of Zn-Cu ferrite nanoparticles for LPG sensing.

    PubMed

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

    2013-01-01

    Nanostructured zinc-copper mixed ferrite was synthesized using sol-gel method. XRD patterns of different compositions of zinc-copper ferrite, Zn(1-x)Cu(x)Fe2O4 (x = 0.0, 0.25, 0.50, 0.75), revealed single phase inverse spinel ferrite in all the samples synthesized. With increasing copper concentration, the crystallite size was found to be increased from 28?nm to 47?nm. The surface morphology of all the samples studied by the Scanning Electron Microscopy there exhibits porous structure of particles throughout the samples. The pellets of the samples are prepared for LPG sensing characteristics. The sensing is carried out at different operating temperatures (200, 225, and 250°C) with the variation of LPG concentrations (0.2, 0.4, and 0.6 vol%). The maximum sensitivity of 55.33% is observed at 250°C operating for the 0.6 vol% LPG. PMID:23864833

  16. Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles

    SciTech Connect

    Mukherjee, A., E-mail: soumen.basu@phy.nitdgp.ac.in; Banerjee, M., E-mail: soumen.basu@phy.nitdgp.ac.in; Basu, S., E-mail: soumen.basu@phy.nitdgp.ac.in [Department of Physics, National Institute of Technology, Durgapur-713209 (India); Pal, M. [CSIR-Central Mechanical Engineering Research Institute, Durgapur-713209 (India)

    2014-04-24

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

  17. Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

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

    Microsoft Academic Search

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

    2007-01-01

    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

  19. Magnetic Silver-Coated Ferrite Nanoparticles and Their Application in Thick Films

    NASA Astrophysics Data System (ADS)

    Liu, Jianguo; Huang, Baling; Li, Xiangyou; Li, Ping; Zeng, Xiaoyan

    2010-12-01

    Magnetic silver-coated ferrite nanoparticles with 39.8% weight gain (relative to ferrite nanopowder coated by a silver layer) were synthesized by electroless deposition of silver on ferrite nanopowder. The mechanism of the electroless deposition was explored in terms of pretreatment, sensitization, activation, and the reduction of silver-ammonia complexes. Experiments showed that the optimal deposition conditions were a temperature of 50°C, pH value of 10 to 12, duration of 65 min with ethanol plus polyethylene glycol as additives, and ultrasonic vibration as a method of dispersing the nanoparticles. From transmission electron microscopy (TEM) images, it was observed that as-synthesized nanoparticles had a core-shell structure with a particle size of 35 nm to 90 nm and a shell thickness of 5 nm to 20 nm. X-ray diffraction (XRD) analysis confirmed that only ferrite and metallic silver were present in the product. Electrical resistance and magnetic hysteresis measurements demonstrated that the nanoparticles were both electrically conductive (volume electrical resistivity on the order of 10-4 ? cm to 10-3 ? cm when compressed to pressure of 2 × 10 6 Pa) and possessed ferrimagnetic properties. After a thick-film paste, obtained with the nanoparticles as the functional phase, was directly written and sintered, scanning electron microscopy (SEM) analysis and electrical resistance measurements of conductive lines in the acquired array pattern showed that an electrically conductive network with some defects and cavities was formed, with a volume electrical resistivity of 1 × 10-4 ? cm to 1 × 10-3 ? cm.

  20. 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

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Ursache-Oprisan, Manuela; Foca-nici, Ecaterina; Cirlescu, Aurelian; Caltun, Ovidiu; Creanga, Dorina

    2010-12-01

    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 10-14-10-15/cm3) 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.

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

    PubMed Central

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

    2014-01-01

    Pediatric brain tumors (PBTs) are a leading cause of death in children. For an improved prognosis in patients with PBTs, there is a critical need to develop molecularly-specific imaging agents to monitor disease progression and response to treatment. In this paper, we describe manganese-containing Prussian blue nanoparticles as agents for molecular magnetic resonance imaging (MRI) and fluorescence-based imaging of PBTs. Our core-shell nanoparticles consist of a core lattice structure that incorporates and retains paramagnetic Mn2+ ions, and generates MRI contrast (both negative and positive). The biofunctionalized shell is comprised of fluorescent avidin, which serves the dual purpose of enabling fluorescence imaging and functioning as a platform for the attachment of biotinylated ligands that target PBTs. The surfaces of our nanoparticles are modified with biotinylated antibodies targeting neuron-glial antigen 2 or biotinylated transferrin. Both neuron-glial antigen 2 and the transferrin receptor are protein markers overexpressed in PBTs. We describe the synthesis, biofunctionalization, and characterization of these multimodal nanoparticles. Further, we demonstrate the MRI and fluorescence imaging capabilities of manganese-containing Prussian blue nanoparticles in vitro. Finally, we demonstrate the potential of these nanoparticles as PBT imaging agents by measuring their organ and brain biodistribution in an orthotopic mouse model of PBTs using ex vivo fluorescence imaging. PMID:24920896

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

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

    SciTech Connect

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

    2012-03-30

    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.

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

    SciTech Connect

    Ghasemi, Ali, E-mail: ali13912001@yahoo.com [Materials Engineering Department, Malek Ashtar University of Technology, Shahin Shahr (Iran, Islamic Republic of); Paesano, Andrea; Cerqueira Machado, Carla Fabiana [Departamento de Física, Centro de Ciências Exatas, Universidade Estadual de Maringá, Maringá (Brazil); Shirsath, Sagar E. [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (India); Spin Device Technology Center, Faculty of Engineering, Shinshu University, Nagano (Japan); Liu, Xiaoxi; Morisako, Akimitsu [Spin Device Technology Center, Faculty of Engineering, Shinshu University, Nagano (Japan)

    2014-05-07

    In current research work, Co{sub 1-x}Ni{sub x/2}Sr{sub x/2}Fe{sub 2}O{sub 4} (x?=?0–1 in a step of 0.2) ferrite nanoparticles were synthesized by a sol-gel method. According to the evolution in the subspectral areas obtained from Mössbauer spectroscopy, it was found that the relaxing iron belongs mostly to the site B, since the Mössbauer fraction of site A does not vary appreciably. With an increase in Ni-Sr substitution contents in cobalt ferrite, the coercivity and saturation of magnetization decrease. Variation of reflection loss versus frequency in microwave X-band demonstrates that the reflection peak shifts to lower frequency by adding substituted cations and the synthesized nanoparticles can be considered for application in electromagnetic wave absorber technology.

  6. Comparative Cytogenetic Study on the Toxicity of Magnetite and Zinc Ferrite Nanoparticles in Sunflower Root Cells

    NASA Astrophysics Data System (ADS)

    Foca-nici, Ecaterina; Capraru, Gabriela; Creanga, Dorina

    2010-12-01

    In this experimental study the authors present their results regarding the cellular division rate and the percentage of chromosomal aberrations in the root meristematic cells of Helianthus annuus cultivated in the presence of different volume fractions of magnetic nanoparticle suspensions, ranging between 20 and 100 microl/l. The aqueous magnetic colloids were prepared from chemically co-precipitated ferrites coated in sodium oleate. Tissue samples from the root meristeme of 2-3 day old germinated seeds were taken to prepare microscope slides following Squash method combined with Fuelgen techniques. Microscope investigation (cytogenetic tests) has resulted in the evaluation of mitotic index and chromosomal aberration index that appeared diminished and respectively increased following the addition of magnetic nanoparticles in the culture medium of the young seedlings. Zinc ferrite toxic influence appeared to be higher than that of magnetite, according to both cytogenetic parameters.

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

    Microsoft Academic Search

    Razia Nongjai; Khalid Mujasam Batoo; Shakeel Khan

    2010-01-01

    Ferrite nanoparticles of basic composition Ni0.7Mg0.3Fe2-xAlxO4 (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 (sigmaac), with frequency reveals

  8. Enhanced Néel temperature in Mn ferrite nanoparticles linked to growth-rate-induced cation inversion

    Microsoft Academic Search

    Aria Yang; C. N. Chinnasamy; J. M. Greneche; Yajie Chen; Soack D. Yoon; Zhaohui Chen; Kailin Hsu; Zhuhua Cai; Kate Ziemer; C. Vittoria; V. G. Harris

    2009-01-01

    Mn ferrite (MnFe2O4) nanoparticles, having diameters from 4 to 50 nm, were synthesized using a modified co-precipitation technique in which mixed metal chloride solutions were added to different concentrations of boiling NaOH solutions to control particle growth rate. Thermomagnetization measurements indicated an increase in Néel temperature corresponding to increased particle growth rate and particle size. The Néel temperature is also

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

    PubMed

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

    2014-04-01

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

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

    SciTech Connect

    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

    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.

  11. Investigations on Laser Beam Welding Dissimilar Material Combinations of Austenitic High Manganese (FeMn) and Ferrite Steels

    NASA Astrophysics Data System (ADS)

    Behm, Velten; Höfemann, Matthias; Hatscher, Ansgar; Springer, André; Kaierle, Stefan; Hein, David; Otto, Manuel; Overmeyer, Ludger

    For the past few years the customer's demand for more fuel efficient and at the same time safer vehicles has steadily increased. Consequently, light weight design has become one of the main interests in engineering. With regard to sheet metal components, a new class of high manganese steels, based on the TWIP (twinning induced plasticity) effect, provides the opportunity of shaping light weight designedthin and complex sheet metal geometries with advanced crash performance. In terms of weldability, due to their thermo-physical properties (high content of C, Mn, Al, Si), FeMn steels have to be handled differently in comparison to conventional steel grades. Particularly dissimilar material combinations of FeMn and ferrite steels are in the center of interest for industrial applications. This study reveals that metallurgical properties of dissimilar welding seams can be influenced considerably by laser beam welding, resulting in a change of the mechanical properties of the seam which is practicable without using filler material as described in (Flügge et al., 2011).

  12. Morphology of cobalt ferrite nanoparticle-polyelectrolyte multilayered nanocomposites

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    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.

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

    PubMed Central

    Drašler, Barbara; Drobne, Damjana; Novak, Sara; Valant, Janez; Boljte, Sabina; Otrin, Lado; Rappolt, Michael; Sartori, Barbara; Igli?, Aleš; Kralj-Igli?, Veronika; Šuštar, Vid; Makovec, Darko; Gyergyek, Sašo; Ho?evar, Matej; Godec, Matjaž; Zupanc, Jernej

    2014-01-01

    Background The purpose of this work is to provide experimental evidence on the interactions of suspended nanoparticles with artificial or biological membranes and to assess the possibility of suspended nanoparticles interacting with the lipid component of biological membranes. Methods 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid vesicles and human red blood cells were incubated in suspensions of magnetic bare cobalt ferrite (CoFe2O4) or citric acid (CA)-adsorbed CoFe2O4 nanoparticles dispersed in phosphate-buffered saline and glucose solution. The stability of POPC giant unilamellar vesicles after incubation in the tested nanoparticle suspensions was assessed by phase-contrast light microscopy and analyzed with computer-aided imaging. Structural changes in the POPC multilamellar vesicles were assessed by small angle X-ray scattering, and the shape transformation of red blood cells after incubation in tested suspensions of nanoparticles was observed using scanning electron microscopy and sedimentation, agglutination, and hemolysis assays. Results Artificial lipid membranes were disturbed more by CA-adsorbed CoFe2O4 nanoparticle suspensions than by bare CoFe2O4 nanoparticle suspensions. CA-adsorbed CoFe2O4-CA nanoparticles caused more significant shape transformation in red blood cells than bare CoFe2O4 nanoparticles. Conclusion Consistent with their smaller sized agglomerates, CA-adsorbed CoFe2O4 nanoparticles demonstrate more pronounced effects on artificial and biological membranes. Larger agglomerates of nanoparticles were confirmed to be reactive against lipid membranes and thus not acceptable for use with red blood cells. This finding is significant with respect to the efficient and safe application of nanoparticles as medicinal agents. PMID:24741305

  14. Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications.

    PubMed

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

    2014-11-01

    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

  15. Structural and electrical properties of neodymium substituted cobalt ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Xavier, S.; Thankachan, S.; Jacob, B. P.; Mohammed, E. M.

    2015-02-01

    A series of polycrystalline spinel ferrites with composition CoFe2-xNdxO4(x=0.0, 0. 05, 0.1, 0.15, 0.2, 0.25) have been synthesized by sol gel method. The structural characterizations of the prepared samples were done using XRD and TEM. The crystallite size shows an increase with the increase in the concentration of neodymium. The activation energy has been calculated from the temperature dependent DC conductivity measurements. The dielectric properties were studied and analyzed as a function of frequency. All the samples exhibit normal dielectric behaviour which is attributed to Maxwell- Wagner interfacial polarization.

  16. Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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

  17. Synthesis of manganese spinel nanoparticles at room temperature by coprecipitation

    SciTech Connect

    Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.fr [GREMAN, UMR 7347 CNRS-CEA, Universite Francois Rabelais, 15 rue de la chocolaterie, 41000 BLOIS (France); Autret-Lambert, C.; Mathieu, C.; Chartier, T.; Delorme, F. [GREMAN, UMR 7347 CNRS-CEA, Universite Francois Rabelais, 15 rue de la chocolaterie, 41000 BLOIS (France); Seron, A [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 ORLEANS Cedex 2 (France)

    2012-08-15

    This paper is focused on a new route to synthesize Mn{sub 3}O{sub 4} nanoparticles by alkalisation by sodium hydroxide on a manganeous solution at room temperature. The precipitates obtained at different pH values have been characterized by XRD and TEM. Since the first addition of sodium hydroxide, a white Mn(OH){sub 2} precipitate appears. At pH=7, {gamma}-MnOOH phase is predominant with needle like shaped particles. At pH=10, hausmanite nanoparticles, which exhibits well defined cubic shape in the range 50-120 nm are obtained. This new precipitation route is a fast and easy environmentally friendly process to obtain well crystallized hausmanite nanoparticles. - Graphical abstract: TEM image showing Mn{sub 3}O{sub 4} particles after a precipitation at pH=10. Highlights: Black-Right-Pointing-Pointer A new route to synthesize Mn{sub 3}O{sub 4} nanoparticles has been demonstrated. Black-Right-Pointing-Pointer Synthesis has been performed by precipitation at room temperature. Black-Right-Pointing-Pointer The size of the Mn{sub 3}O{sub 4} nanoparticles is between 50 and 120 nm.

  18. Preparation and magnetic properties of barium ferrites substituted with manganese, cobalt, and tin

    Microsoft Academic Search

    Yue Liu; Michael G. B. Drew; Ying Liu

    2011-01-01

    Barium ferrites substituted by Mn–Sn, Co–Sn, and Mn–Co–Sn with general formulae BaFe12?2xMnxSnxO19 (x=0.2–1.0), BaFe12?2xCoxSnxO19 (x=0.2–0.8), and BaFe12?2xCox\\/2Mnx\\/2SnxO19 (x=0.1–0.6), respectively, have been prepared by a previously reported co-precipitation method. The efficiency of the method was refined by lowering the reaction temperature and shortening the required reaction time, due to which crystallinity improved and the value of saturated magnetization increased as well.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

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

    SciTech Connect

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

    2007-02-15

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

  1. Preparation and characterization of ultra-stable biocompatible magnetic fluids using citrate-coated cobalt ferrite nanoparticles

    Microsoft Academic Search

    P. C. Morais; R. L. Santos; A. C. M. Pimenta; R. B. Azevedo; E. C. D. Lima

    2006-01-01

    Preparation and characterization of ultra-stable biocompatible cobalt ferrite-based magnetic fluids has been reported. Synthesized samples have core particle diameter in the range of 4.7 to 14.8 nm, as indicated by TEM. Chemical and crystalline data show that the prepared nanoparticles are cobalt ferrite with a slight deviation from the Fe:Co::2:1 stoichiometry. ATR-FTIR spectroscopy was used to investigate the citrate adsorption

  2. Relations between magneto-optical properties and reactivity in cobalt-manganese ferrite thin films and powders

    Microsoft Academic Search

    Laurence Bouet; Philippe Tailhades; Abel Rousset

    1996-01-01

    Co-Mn spinel ferrites were prepared as submicron powders and thin films. Because of their finely divided state, these spinels could be oxidized at low temperatures to give novel cation-deficient ferrites. For these two material forms, the magneto-optical properties were found to be strongly dependent on the ferrite oxidation state. The highest coercivities and Faraday rotations were obtained when the ferrites

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

    PubMed

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

    2012-05-01

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

  4. Influence of copper cations on the magnetic properties of NiCuZn ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Ghasemi, Ali; Ghasemi, Ebrahim; Paimozd, Ebrahim

    2011-06-01

    Ni 0.6- xCu xZn 0.4Fe 2O 4 ( x=0-0.5) ferrite nanoparticles were prepared, employing a reverse micelle process. X-ray diffraction and transmission electron microscopy evaluations demonstrated that single phase spinel ferrites with narrow size distribution were obtained. Vibrating sample magnetometer was employed to probe the magnetic properties of the samples. It was found that with an increase in copper content, the saturation magnetization decreases. Magnetic dynamics of the samples was studied by measuring a.c. magnetic susceptibility versus temperature at different frequencies. The phenomenological Néel-Brown and Vogel-Fulcher models were employed to distinguish between the interacting or non-interacting systems. The system exhibits that there is strong interaction among fine particles.

  5. Composition and hydrophilicity control of Mn-doped ferrite (MnxFe3-xO4) nanoparticles induced by polyol differentiation.

    PubMed

    Vamvakidis, Kosmas; Katsikini, Maria; Vourlias, George; Angelakeris, Mavroeidis; Paloura, Eleni C; Dendrinou-Samara, Catherine

    2015-03-10

    Manganese doped ferrite (MnxFe3-xO4) nanoparticles with x = 0.29-0.77 were prepared under solvothermal conditions in the presence solely of a polyol using the trivalent manganese and iron acetylacetonates as precursors. In this facile approach, a variety of polyols such as polyethylene glycol (PEG 8000), tetraethylene glycol (TEG), propylene glycol (PG) and a mixture of TEG and PG (1?:?1) were utilized in a triple role as a solvent, a reducing agent and a surface-functionalizing agent. The composition of the fine cubic-spinel structures was found to be related to the reductive ability of each polyol, while determination of structural characteristics plus the inversion parameter (i = 0.18-0.38) were provided by X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy at both the Fe and Mn K-edges. The saturation magnetization increased up to 80 emu g(-1) when x = 0.35 and i = 0.22. In addition, the as-prepared nanocrystals coated with PEG, PG and PG&TEG showed excellent colloidal stability in water, while the TEG-coated particles were not water dispersible and converted to hydrophilic when were extra PEGylated. Measurements of the (1)H NMR relaxation in water were carried out and the nanoprobes were evaluated as potential contrast agents. PMID:25689845

  6. Low temperature polymer assisted hydrothermal synthesis of bismuth ferrite nanoparticles

    Microsoft Academic Search

    Yonggang Wang; Gang Xu; Zhaohui Ren; Xiao Wei; Wenjian Weng; Piyi Du; Ge Shen; Gaorong Han

    2008-01-01

    BFO nanoparticles were successfully synthesized by a polymer assisted hydrothermal method at a temperature as low as 160°C. The as-prepared powders, characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM), exhibited a pure BFO phase about 10nm size and uniform sphere-like shape. It was found that the added polymer played a key role in decreasing the growing speed of

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

    SciTech Connect

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

    2009-11-02

    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.

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

    SciTech Connect

    Wu Jiagang [Department of Materials Science, Sichuan University, 610064 (China); Department of Materials Science and Engineering, National University of Singapore, 117574 (Singapore); Wang, John [Department of Materials Science and Engineering, National University of Singapore, 117574 (Singapore); Xiao Dingquan; Zhu Jianguo [Department of Materials Science, Sichuan University, 610064 (China)

    2011-06-15

    BiFe{sub 0.95}R{sub 0.05}O{sub 3} (Mn{sup 2+}, Mn{sup 3+}, and Mn{sup 4+}) thin films with (110) orientation were fabricated on SrRuO{sub 3}/Pt/TiO{sub 2}/SiO{sub 2}/Si(100) substrates via rf sputtering. With the increasing valence of Mn in BiFe{sub 0.95}R{sub 0.05}O{sub 3}, the concentration of Fe{sup 2+} increases, whereas the concentration of oxygen vacancies decreases. The electrical properties of BiFe{sub 0.95}R{sub 0.05}O{sub 3} 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 2P{sub r} {approx} 145.2 {mu}C/cm{sup 2} is obtained for the Mn{sup 4+}-doped film. For the Mn{sup 2+}-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 Mn{sup 3+}- and Mn{sup 4+}-doped films regardless of negative and positive directions or measurement temperatures.

  9. Influence of SiO2 matrix and annealing time on properties of Ni-ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Nadeem, K.; Krenn, H.; Shahid, M.; Letofsky-Papst, I.

    2013-05-01

    Nickel ferrite nanoparticles dispersed in SiO2 matrix have been synthesized by using sol-gel method. Influence of SiO2 concentration and annealing time on properties of nickel ferrite nanoparticles have been studied in detail in order to synthesize small (diameter around 10 nm) nickel ferrite nanoparticles with improved magnetic properties. Structural characterization includes X-ray diffraction (XRD) and transmission electron microscopy (TEM). Magnetic measurements have been done using SQUID-magnetometer. Average particle size decreases with increasing SiO2 matrix concentration, while it shows an increasing trend with increasing annealing time. The decrease of particle size at higher SiO2 concentration is due to large number of nucleation centers which finally restrict the nanoparticle growth. Saturation magnetization shows a decreasing trend with increasing SiO2 matrix concentration, while coercivity behaves oppositely and is attributed to increased number of disordered surface spins in small nanoparticles. Magnetic properties of the small nanoparticles have been improved on increasing annealing time with a corresponding increase in crystallite size. Therefore control over nanoparticle size, nanoparticle distribution, and magnetic properties could be achieved using optimum SiO2 matrix concentration and annealing time.

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

    PubMed

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

    2014-06-01

    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

  11. Synthesis of manganese ferrite/graphene oxide nanocomposites for biomedical applications.

    PubMed

    Peng, Erwin; Choo, Eugene Shi Guang; Chandrasekharan, Prashant; Yang, Chang-Tong; Ding, Jun; Chuang, Kai-Hsiang; Xue, Jun Min

    2012-12-01

    In this study, MnFe(2)O(4) nanoparticle (MFNP)-decorated graphene oxide nanocomposites (MGONCs) are prepared through a simple mini-emulsion and solvent evaporation process. It is demonstrated that the loading of magnetic nanocrystals can be tuned by varying the ratio of graphene oxide/magnetic nanoparticles. On top of that, the hydrodynamic size range of the obtained nanocomposites can be optimized by varying the sonication time during the emulsion process. By fine-tuning the sonication time, MGONCs as small as 56.8 ± 1.1 nm, 55.0 ± 0.6 nm and 56.2 ± 0.4 nm loaded with 6 nm, 11 nm, and 14 nm MFNPs, respectively, are successfully fabricated. In order to improve the colloidal stability of MGONCs in physiological solutions (e.g., phosphate buffered saline or PBS solution), MGONCs are further conjugated with polyethylene glycol (PEG). Heating by exposing MGONCs samples to an alternating magnetic field (AMF) show that the obtained nanocomposites are efficient hyperthermia agents. At concentrations as low as 0.1 mg Fe mL(-1) and under an 59.99 kA m(-1) field, the highest specific absorption rate (SAR) recorded is 1588.83 W g(-1) for MGONCs loaded with 14 nm MFNPs. It is also demonstrated that MGONCs are promising as magnetic resonance imaging (MRI) T(2) contrast agents. A T(2) relaxivity value (r(2) ) as high as 256.2 (mM Fe)(-1) s(-1) could be achieved with MGONCs loaded with 14 nm MFNPs. The cytotoxicity results show that PEGylated MGONCs exhibit an excellent biocompatibility that is suitable for biomedical applications. PMID:22962025

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  13. Highly coercive cobalt ferrite nanoparticles-CuTl-1223 superconductor composites

    NASA Astrophysics Data System (ADS)

    Jabbar, Abdul; Qasim, Irfan; Khan, Shahid A.; Nadeem, K.; Waqee-ur-Rehman, M.; Mumtaz, M.; Zeb, F.

    2015-03-01

    We explored the effects of highly coercive cobalt ferrite (CoFe2O4) nanoparticles addition on structural, morphological, and superconducting properties of Cu0.5Tl0.5Ba2Ca2Cu3O10-? (CuTl-1223} matrix. Series of (CoFe2O4)x/CuTl-1223 (x=0 2.0 wt%) composites samples were synthesized and were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) absorption spectroscopy, and dc-resistivity versus temperature measurements. The magnetic behavior of CoFe2O4 nanoparticles was determined by MH-loops with the help of superconducting quantum interference device (SQUID). MH-loops analysis showed that these nanoparticles exhibit high saturation magnetization (86 emu/g) and high coercivity (3350 Oe) at 50 K. The tetragonal structure of host CuTl-1223 superconducting matrix was not altered after the addition of CoFe2O4 nanoparticles, which gave us a clue that these nanoparticles had occupied the inter-granular sites (grain-boundaries) and had filled the pores. The increase of mass density with increasing content of these nanoparticles in composites can also be an evidence of filling up the voids in the matrix. The resistivity versus temperature measurements showed an increase in zero resistivity critical {Tc(0)}, which could be most probably due to improvement of weak-links by the addition of these nanoparticles. But the addition of these nanoparticles beyond an optimum level caused the agglomeration and produced additional stresses in material and suppressed the superconductivity.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Narayanan, Kannan Badri; Park, Hyun Ho

    2014-10-01

    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.

  16. Electromagnetic properties of NiZn ferrite nanoparticles and their polymer composites

    SciTech Connect

    Parsons, P. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Duncan, K. [U.S. Army, Communications-Electronics Research, Development and Engineering Center, Space and Terrestrial Communications Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Giri, A. K. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Bowhead Science and Technology, LLC, Belcamp, Maryland 21017 (United States); Xiao, J. Q. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Karna, S. P., E-mail: shashi.p.karna.civ@mail.mil [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States)

    2014-05-07

    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?Am{sup 2}?kg{sup ?1} and 14?Am{sup 2}?kg{sup ?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?Am{sup 2}?kg{sup ?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.

  17. Magnetocaloric effect in Ni-Zn ferrite nanoparticles prepared by using solution combustion

    NASA Astrophysics Data System (ADS)

    Lee, K. D.; Kambale, R. C.; Hur, N.

    2014-12-01

    Ni x Zn1- x Fe2O4 ( x = 0.2 and 0.3) ferrite nanoparticles with sizes ranging from 65 to 70 nm were synthesized employing the solution combustion route. The magnetocaloric behavior was investigated within the 50 K ? T ? 400 K range of temperatures ( T). The entropy change (? S) and the adiabatic temperature change (? T) were derived from magnetization ( M) and specific heat ( C P ) measurements. Both compositions exhibited broad peaks for the isothermal entropy change. The magnetic field ( H)-dependent ? T was analyzed within the mean-field approximation scheme, and the observed magnetocaloric properties of the nanoparticle samples were compared with those of a bulk sample. Our study suggests that the magnetocaloric properties of magnetic oxides strongly depend on the particle size; thus, particle size should be considered as a key tuning parameter in the optimization of magnetic refrigeration.

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

    PubMed

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

    2011-06-01

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

  19. Size effect on the static and dynamic magnetic properties of W-type barium ferrite composites: From microparticles to nanoparticles

    Microsoft Academic Search

    Z. W. Li; G. Q. Lin; Linfeng Chen; Y. P. Wu; C. K. Ong

    2005-01-01

    The static, dynamic, and attenuation properties of BaCoZnFe16O27 barium ferrites and their composites have been studied using microparticles and nanoparticles. The results showed that BaCoZnFe16O27 microparticles have larger saturation magnetization Ms and smaller coercivity Hc than do nanoparticles. The composites with microparticles have significantly larger real and imaginary permeabilities mu0' and mumax'' due to their multidomain structures, but low resonance

  20. Size effect on the static and dynamic magnetic properties of W-type barium ferrite composites: From microparticles to nanoparticles

    Microsoft Academic Search

    Z. W. Li; G. Q. Lin; Linfeng Chen; Y. P. Wu; C. K. Ong

    2005-01-01

    The static, dynamic, and attenuation properties of BaCoZnFe16O27 barium ferrites and their composites have been studied using microparticles and nanoparticles. The results showed that BaCoZnFe16O27 microparticles have larger saturation magnetization Ms and smaller coercivity Hc than do nanoparticles. The composites with microparticles have significantly larger real and imaginary permeabilities ?0? and ?max? due to their multidomain structures, but low resonance

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

    SciTech Connect

    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

    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.

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

    PubMed Central

    2011-01-01

    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

  3. [Investigation of the interaction between DNA and cobalt ferrite nanoparticles by FTIR spectroscopy].

    PubMed

    Pershina, A G; Sazonov, A E; Ogorodova, L M

    2009-01-01

    The interaction of DNA with nanoparticles of cobalt ferrite powder prepared by the mechano-chemical method was studied. It was shown that CoFe(2)O(4) nanoparticles efficiently bind DNA in aqueous solutions (Tris-HCl), forming a bionanocomposite. The adsorption capacity of CoFe(2)O(4) nanoparticles for DNA was evaluated to be 5.25 x 10(-3) mol/m(2). The desorption of DNA from the surface of the particles was analyzed while changing the pH, the ionic strength, and the chemical content of the medium. The DNA-CoFe(2)O(4) nanocomposite was investigated by FTIR spectroscopy. The block of the data allowed one to consider the mechanism of the interaction between a polynucleotide and CoFe(2)O(4) nanoparticles and to make the assumption that the binding occurred due to the coordination interaction of the phosphate groups and heterocyclic bases of DNA (oxygen atoms of thymine and guanine) with metal ions on the particle surface. The analysis of the IR spectra showed that binding can lead to the partial destabilization of the DNA structure, with the B conformation of a polynucleotide being preserved. PMID:19915646

  4. Magnetic properties of cobalt-ferrite nanoparticles embedded in polystyrene resin

    SciTech Connect

    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

    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.

  5. Synthesis of cobalt ferrite core/metallic shell nanoparticles for the development of a specific PNA/DNA biosensor.

    PubMed

    Pita, Marcos; Abad, José María; Vaz-Dominguez, Cristina; Briones, Carlos; Mateo-Martí, Eva; Martín-Gago, José Angel; Morales, Maria del Puerto; Fernández, Víctor M

    2008-05-15

    Controlled synthesis of cobalt ferrite superparamagnetic nanoparticles covered with a gold shell has been achieved by an affinity and trap strategy. Magnetic nanoparticles are functionalized with a mixture of amino and thiol groups that facilitate the electrostatic attraction and further chemisorption of gold nanoparticles, respectively. Using these nanoparticles as seeds, a complete coating shell is achieved by gold salt-iterative reduction leading to monodisperse water-soluble gold-covered magnetic nanoparticles, with an average diameter ranging from 21 to 29 nm. These constitute a versatile platform for immobilization of biomolecules via thiol chemistry, which is exemplified by the immobilization of peptide nucleic acid (PNA) oligomers that specifically hybridize with complementary DNA molecules in solution. Hybridation with DNA probes has been measured using Rhodamine 6G fluorescence marker and the detection of a single nucleotide mutation has been achieved. These results suggest the PNA-nanoparticles application as a biosensor for DNA genotyping avoiding commonly time-consuming procedures employed. PMID:18329659

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

    PubMed

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

    2012-09-01

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

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

    SciTech Connect

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

    2012-02-28

    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.

  8. Synergetic effect of size and morphology of cobalt ferrite nanoparticles on proton relaxivity.

    PubMed

    N, Venkatesha; Srivastava, Chandan; Hegde, Veena

    2014-12-01

    Cobalt ferrite nanoparticles with average sizes of 14, 9 and 6 nm were synthesised by the chemical co-precipitation technique. Average particle sizes were varied by changing the chitosan surfactant to precursor molar ratio in the reaction mixture. Transmission electron microscopy images revealed a faceted and irregular morphology for the as-synthesised nanoparticles. Magnetic measurements revealed a ferromagnetic nature for the 14 and 9 nm particles and a superparamagnetic nature for the 6 nm particles. An increase in saturation magnetisation with increasing particle size was noted. Relaxivity measurements were carried out to determine T2 value as a function of particle size using nuclear magnetic resonance measurements. The relaxivity coefficient increased with decrease in particle size and decrease in the saturation magnetisation value. The observed trend in the change of relaxivity value with particle size was attributed to the faceted nature of as-synthesised nanoparticles. Faceted morphology results in the creation of high gradient of magnetic field in the regions adjacent to the facet edges increasing the relaxivity value. The effect of edges in increasing the relaxivity value increases with decrease in the particle size because of an increase in the total number of edges per particle dispersion. PMID:25429495

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  10. Solar photocatalytic degradation of RB5 by ferrite bismuth nanoparticles synthesized via ultrasound.

    PubMed

    Soltani, T; Entezari, M H

    2013-09-01

    In this paper, the photocatalytic degradation of Reactive Black 5 (RB5) was investigated with ferrite bismuth synthesized via ultrasound under direct sunlight irradiation. The intensity of absorption peaks of RB5 gradually decreased by increasing the irradiation time and finally vanished in 50 min in acidic medium. The formation of new intermediate was observed in basic medium. The relative concentration of RB5 in solution and on the surface of ferrite bismuth (BiFeO3) nanoparticles was considered during the experiment in acidic and basic media. The effects of various parameters such as amount of catalyst, concentration of dye, and pH of the solution have been studied on the dye degradation. The adsorption isotherm and the kinetic of photocatalytic degradation of RB5 were investigated. The adsorption constants in the dark and in the presence of sunlight irradiation were compared. The photocatalytic degradation mechanism of RB5 has been evaluated through the addition of some scavengers to the solution. In addition, the stability and reusability of the catalyst were examined in this work. PMID:23466007

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

    PubMed

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

    2009-07-01

    Nanoparticles of manganese perovskite of the composition La(0.75)Sr(0.25)MnO(3) 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 hysteresis loops in the alternating field revealed high specific power losses, further enhanced by the encapsulation procedure in the case of the coated particles. The corresponding results are discussed on the basis of complex characterization of the particles and especially detailed magnetic measurements. Moreover, the Curie temperature (335 K) of the selected magnetic cores resolves the risk of local overheating during hyperthermia treatment. PMID:19531865

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

    PubMed

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

    2012-08-01

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

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

    PubMed

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

    2011-11-30

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

  15. Magnetoelectric behavior of carbonyl iron mixed Mn oxide-coated ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Ahad, Faris B. Abdul; Lee, Shang-Fan; Hung, Dung-Shing; Yao, Yeong-Der; Yang, Ruey-Bin; Lin, Chung-Kwei; Tsay, Chien-Yie

    2010-05-01

    The dielectric and magnetic properties of manganese oxide-coated Fe3O4 nanoparticles (NPs) were measured by the cavity perturbation method at x-band microwave frequencies ranging from 7-12.5 GHz with controlled external magnetic field up to 2.2 kOe at room temperature. Different ratios (5%, 10%, and 20% by weight) of coated NPs were prepared by sol-gel method then mixed with carbonyl iron powder in epoxy matrix. The saturation magnetization is inversely proportional to the NPs ratio in the mixture between 150 and 180 emu/g. The real part of the permittivity decreased with increasing NPs concentration, but the permittivity change by magnetic field increased. The tunability behavior is explained by insulator-ferromagnetic interface magnetoelectricity and the large surface volume ratio for the NPs.

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

    NASA Astrophysics Data System (ADS)

    Ghasemi, Ali

    2013-03-01

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

  17. Incorporation of cobalt-ferrite nanoparticles into a conducting polymer in aqueous micellar medium: strategy to get photocatalytic composites.

    PubMed

    Endr?di, Balázs; Hursán, Dorottya; Petrilla, Liliána; Bencsik, Gábor; Visy, Csaba; Chams, Amani; Maslah, Nabiha; Perruchot, Christian; Jouini, Mohamed

    2014-01-01

    In this study an easy strategy for conducting polymer based nanocomposite formation is presented through the deposition of cobalt-ferrite (CoFe(2)O(4)) containing poly(3,4-ethylenedioxythiophene) (PEDOT) thin layers. The electrochemical polymerization has been performed galvanostatically in an aqueous micellar medium in the presence of the nanoparticles and the surface active Triton X-100. The nanoparticles have been characterized by Transmission electron microscopy (TEM), the thin layers has been studied by applying Scanning electron microscopy (SEM), and X-ray diffraction (XRD), and the basic electrochemical properties have been also determined. Moreover, electrocatalytic activity of the composite was demonstrated in the electrooxidation reaction of dopamine (DA). The enhanced sensitivity - related to the cobalt-ferrite content - and the experienced photocatalyitic activity are promising for future application. PMID:25125121

  18. Millimeter-wave magneto-dielectric effects in self-assembled ferrite-ferroelectric core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    The magneto-dielectric effect (MDE) involves studies on the influence of an applied magnetic field on the dielectric constant of a material. MDEs in self-assembled core-shell nanoparticles of nickel ferrite and barium titanate have been investigated in the millimeter wave frequencies. The core-shell nanocomposites were synthesized by coating 15 nm nickel ferrite and 100 nm barium titanate nanoparticles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst forming heterogeneous nanocomposites. Studies on MDE in as-assembled particles have been carried out by measurements of the relative permittivity as a function of frequency f under an applied static magnetic field H over 16-24 GHz. Measurements show an H-induced decrease in permittivity by 0.8% for H = 4 kOe and is much stronger than MDE in single phase multiferroics. A model for the high frequency MDE has been discussed here.

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

    Microsoft Academic Search

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

    2009-01-01

    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

  20. Functional Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Gass, James

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

  1. Effects of Thermal Annealing on Structural and Magnetic Properties of Lithium Ferrite Nanoparticles

    SciTech Connect

    Jovic, Natasa G.; Masadeh, Ahmad S.; Kremenovic, Aleksandar S.; Antic, Bratislav V.; Blanusa, Jovan L.; Cvjeticanin, Nikola D.; Goya, Gerardo F.; Antisari, Marco Vittori; Bozin, Emil S.; (FPC-Serbia); (MSU); (Zaragoza); (ENEA); (Columbia); (Vinca)

    2010-01-12

    Pure, crystalline, {approx}10 nm lithium ferrite phase (Li{sub 0.5}Fe{sub 2.5}O{sub 4}), was successfully synthesized at very low temperature using a modified combustion method. The crystal structure and microstructure evolution of this system upon annealing were monitored by a careful investigation of X-ray diffractograms collected on a synchrotron source. Comparative analysis of the results obtained from the full profile Rietveld method (in reciprocal space) and the pair distribution function method (in direct space) was carried out. Nanocrystalline samples exhibit similar crystal structure, on average, with a partial ordering of Li{sup +} and Fe{sup 3+} ions between octahedral 4b and 12d sites on the spinel crystal lattice (space group P4{sub 3}32). After annealing at 973 K, cation distribution changes to a completely ordered, resembling that which is seen in the bulk lithium ferrite. The PDF analysis reveals abnormally high values of oxygen atomic displacement parameters in tetrahedral 8c sites (O1) indicating a significant disordering of the O1 network and suggests migration of lithium ions from 4b sites to the outer layers of nanoparticles. Analysis of room temperature Moessbauer spectra has shown that the hyperfine field for Fe{sup 3+} ions in tetrahedral 8c sites is the most sensitive on increasing the particle size and improving the crystallinity. From the differential thermal analysis, it was found that a lower driving force is required to induce an order-disorder phase transition in nanocrystalline samples, compared to the bulk-like sample, presumably due to the higher crystal disordering in these samples.

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

    PubMed

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

    2012-08-01

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

  3. Chitosan-mediated formation of biomimetic silica nanoparticles: an effective method for manganese peroxidase immobilization and stabilization.

    PubMed

    Luan, Pan-Pan; Jiang, Yan-Jun; Zhang, Song-Ping; Gao, Jing; Su, Zhi-Guo; Ma, Guang-Hui; Zhang, Yu-Fei

    2014-11-01

    Our work here, for the first time, reported the use of chitosan-mediated biomimetic silica nanoparticles in enzyme immobilization. In order to make clear the relationship among silicification process, silica nanoparticle structure and immobilized enzyme activity, a mechanism of chitosan-mediated silicification using sodium silicate as the silica source was primarily evaluated. Chitosan was demonstrated effectively to promote the silicification not only in accelerating the aggregation rate of sodium silicate, but also in templating the formation of silica nanoparticles. Although the whole biomimetic silicification process contained polycondensation-aggregation-precipitation three stages, the elemental unit in precipitated silica was confirmed to be nanoparticles with 100 nm diameter regardless of the chitosan and silicate concentration used. Furthermore, the effect of enzyme on silicification process was also investigated. The introducing of manganese peroxidase (MnP) to silica precursor solution had no obvious effect on the silicification rate and nanoparticle morphology. The residual activity and embedding rate of immobilized MnP were 64.2% and 36.4% respectively under the optimum conditions. In addition, compared to native MnP, the MnP embedded in chitosan/silica nanoparticles exhibited improved stability against organic solvent and ultrasonic wave. After ultrasonic treatment for 20 min, 77% of the initial activity was remained due to the protective effect of chitosan/silica nanoparticles, while native MnP lost almost all of its original activity. PMID:24913823

  4. In depth analysis of apoptosis induced by silica coated manganese oxide nanoparticles in vitro.

    PubMed

    Yu, Chao; Zhou, Zhiguo; Wang, Jun; Sun, Jin; Liu, Wei; Sun, Yanan; Kong, Bin; Yang, Hong; Yang, Shiping

    2015-02-11

    Manganese oxide nanoparticles (MnO NPs) have been regarded as a new class of T1-positive contrast agents. The cytotoxicity of silica coated MnO NPs (MnO@SiO2 NPs) was investigated in human cervical carcinoma cells (HeLa) and mouse fibroblast cells (L929). The changes of cell viability, cell morphology, cellular oxidative stress, mitochondrial membrane potential and cell cycle induced by MnO@SiO2 NPs were evaluated. Compared to HeLa cells, L929 cells showed lower cell viability, more strongly response to oxidative stress and higher percentage in the G2/M phase of cell cycle. The appearance of sub-G1 peak, double staining with Annexin V-FITC/PI and the increase of Caspase-3 activity further confirmed apoptosis should be the major form of cell death. Moreover, the apoptotic pathway was clarified as follows. Firstly, reactive oxygen species (ROS) is generated induced by MnO@SiO2 NPs, then p53 is activated followed by an increase in the bax and a decrease in the bcl-2, ultimately leading to G2/M phase arrest, increasing the activity of caspase-3 and inducing apoptosis. PMID:25464291

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

    PubMed

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

    2011-12-28

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

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

    SciTech Connect

    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

    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.

  7. Manifestation of weak ferromagnetism and photocatalytic activity in bismuth ferrite nanoparticles

    SciTech Connect

    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

    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.

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

    PubMed

    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

    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

  9. Size tuned polyol-made Zn0.9M0.1Fe2O4 (M = Mn, Co, Ni) ferrite nanoparticles as potential heating agents for magnetic hyperthermia: from synthesis control to toxicity survey

    NASA Astrophysics Data System (ADS)

    Basti, H.; Hanini, A.; Levy, M.; Ben Tahar, L.; Herbst, F.; Smiri, L. S.; Kacem, K.; Gavard, J.; Wilhelm, C.; Gazeau, F.; Chau, F.; Ammar, S.

    2014-12-01

    Zn-rich substituted Zn0.9M0.1Fe2O4 (M = Mn, Co, Ni) ferrite nanoparticles (NPs) of about 5 and 10 nm were produced by the so-called polyol method. They were engineered for hyperthermia therapy based on their magnetic and morphological properties. Indeed, because of their comparatively low Curie temperature and reasonable magnetization, these probes may turn into useful self-regulated heating agents under suitable conditions. For such a purpose, the structure, the microstructure, the magnetic and magnetocalorimetric properties of the produced NPs as well as their in vitro cytotoxicity were investigated. Our results demonstrate that the magnetic properties of these magnetically diluted spinel ferrite particles can be largely modified by just changing their size. They also show that the about 10 nm sized manganese-based ones exhibit the highest heating power under a 700 kHz ac magnetic field and the lowest cytotoxicity on Immortalized human umbilical vascular endothelial cells (HUVEC).

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

    PubMed

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

    2012-03-30

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

  11. Low temperature synthesis of bismuth ferrite nanoparticles by a ferrioxalate precursor method

    Microsoft Academic Search

    Sushmita Ghosh; Subrata. Dasgupta; Amarnath Sen; Himadri Sekhar Maiti

    2005-01-01

    The synthesis of bismuth ferrite by solid-state reaction of Bi2O3 and Fe2O3 results in the formation of multiphase products. Even coprecipitation followed by calcination leads to the formation of impurity phases. Here, we report the synthesis of magnetoelectric bismuth ferrite by a ferrioxalate precursor method. In this process, bismuth ferrite, synthesized through solutions of some specific salts led to the

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

    NASA Astrophysics Data System (ADS)

    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

    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

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

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

    NiZn- and NiCuZn-ferrite nanoparticles (50-70 nm) with the chemical formula Ni 0.5 Zn 0.5Fe 2O 4 (NiZn) and Ni 0.35Cu 0.15Zn 0.5Fe 2O 4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83 emu/g (NiZn) to 91 emu/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in the frequency range of 1 MHz-1.8 GHz. Reflection losses ( RL) for both samples were calculated from complex permeability and permittivity. Cu substitution in NiZn-ferrite enhances permeability and RL. In order to explore microwave-absorbing properties in X-band, magnetic nanoparticles were mixed with an epoxy resin to be converted into a microwave-absorbing composite and microwave behaviors of both materials were studied using a microwave vector network analyzer from 7.5 to 13.5 GHz. Cu substitution diminishes absorption intensity in the range 11.5-12.5 GHz.

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

    PubMed Central

    2012-01-01

    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

  15. Electromagnetic characteristics of manganese oxide-coated Fe3O4 nanoparticles at 2-18 GHz

    NASA Astrophysics Data System (ADS)

    Yang, R. B.; Liang, W. F.; Lin, C. K.

    2011-04-01

    The dielectric and magnetic properties of manganese oxide-coated Fe3O4 nanoparticles (NPs) were measured by the transmission/reflection method in 2-18 GHz. MnOx-coated Fe3O4 NPs were prepared by sol-gel method followed by heat-treating at 300, 400, and 500 °C, respectively. The heat-treated powders were then used as magnetic fillers and added to an epoxy resin to prepare MnOx-coated Fe3O4 composites for the complex permittivity (?'-j??) and permeability (?'-j??) measurements. After the sol-gel process, the coating of manganese oxide (mixture of major Mn2O3 and minor Mn3O4) reduced the value of ?'. The lower the heat-treating temperature, the larger the decrease in ?'. The relative decrease in ?', compared with uncoated Fe3O4 nanoparticles, is 28.7, 23.5, and 20.0% for coated MnOx heat-treated at 300, 400, and 500 °C, respectively, while the relative decrease in ?? is 74.1, 68.8, and 65.2%, respectively. In the present study, MnOx-coated Fe3O4 exhibited a significant decrease in dielectric loss tangent of ˜100% compared to that of uncoated NPs and can be of practical use for microwave components.

  16. Low temperature synthesis of bismuth ferrite nanoparticles by a ferrioxalate precursor method

    SciTech Connect

    Ghosh, Sushmita [Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata, West Bengal 700032 (India); Dasgupta, Subrata [Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata, West Bengal 700032 (India)]. E-mail: sdasgupta@cgcri.res.in; Sen, Amarnath [Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata, West Bengal 700032 (India); Maiti, Himadri Sekhar [Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata, West Bengal 700032 (India)

    2005-12-08

    The synthesis of bismuth ferrite by solid-state reaction of Bi{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} results in the formation of multiphase products. Even coprecipitation followed by calcination leads to the formation of impurity phases. Here, we report the synthesis of magnetoelectric bismuth ferrite by a ferrioxalate precursor method. In this process, bismuth ferrite, synthesized through solutions of some specific salts led to the formation of phase pure (perovskite) nanocrystalline powder (11-22 nm as evident from X-ray diffraction analysis) at a temperature of 600 deg. C. The synthesized powders were characterized by X-ray diffractometry, thermogravimetry and differential thermal analysis, Fourier transformation infrared spectroscopy and scanning electron microscopy. The synthesis route is simple, energy saving and cost-effective. Such nanosized bismuth ferrite powder may have a potential application in making lead free piezoelectric materials for actuators as well as magnetoelectric sensors.

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

    Microsoft Academic Search

    Ali Ghasemi; Vladimir Sepelak; Xiaoxi Liu; Akimitsu Morisako

    2009-01-01

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

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

    SciTech Connect

    Kahn, Myrtil L.; Zhang, Z. John

    2001-06-04

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

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

    Microsoft Academic Search

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

    1997-01-01

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

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

    E-print Network

    Gao, Jinming

    -invasive diagnosis and post- therapy assessment of a variety of diseases. MRI contrast can be enhanced by the use.e., Mn2+ occupies both A and B sites), whereas the other metal ferrites have an inverse spinel structure Administration has set the reference daily intake (RDI) doses for Fe and Zn at 18 and 15 mg/day, respectively

  2. Structure and magnetic properties of rf thermally plasma synthesized Mn and MnZn ferrite nanoparticles

    E-print Network

    McHenry, Michael E.

    Structure and magnetic properties of rf thermally plasma synthesized Mn and Mn­Zn ferrite, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 Presented on 13 November 2002 Plasma synthesisW­3 MHz rf radio frequency induction plasma torch. We investigate these materials for soft magnetic

  3. Structural and magnetic properties of magnesium ferrite nanoparticles prepared via EDTA-based sol-gel reaction

    NASA Astrophysics Data System (ADS)

    Hussein, Shaban I.; Elkady, Ashraf S.; Rashad, M. M.; Mostafa, A. G.; Megahid, R. M.

    2015-04-01

    Magnesium ferrite (MgFe2O4) nanoparticles have been prepared, for the first time, by ethylene diamine tetraacetic acid (EDTA)-based sol-gel combustion method. The prepared ferrite system is calcined at 400, 500 and 600 °C. Thermo-gravimetric and differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometry (VSM) were applied for elucidating the structural and magnetic properties of the prepared system. XRD patterns revealed that the prepared system have two spinel MgFe2O4 structures, namely cubic and tetragonal phases that are dependent on calcination temperature (Tc). The crystallite sizes varied from 8.933 to 41.583 nm, and from 1.379 to 292.565 nm for the cubic and tetragonal phases respectively depending on Tc. The deduced lattice parameters for the cubic and (tetragonal) systems are a=8.368, 8.365 and 8.377 and (a=7.011, 5.922, 5.908 and c=6.622, 8.456, 8.364) Å at Tc=400, 500 and 600 °C respectively. While the cation distribution of the cubic phase is found to be mixed spinel and Tc-dependent, it is an inverse spinel in the tetragonal phase where the Fe3+ ions occupy both the tetrahedral A- and octahedral B-sites in almost equal amount; the Mg2+ ions are found to occupy only the B-sites. The HRTEM and selected-area electron diffraction (SAED) revealed the detailed morphology of the nanoparticles, and confirmed their crystalline spinel structure. VSM indicated the existence of an appreciable fraction of superparamagnetic particles at room temperature, with pure superparamagnetic behavior observed for samples calcined at 400 °C. Besides, the magnetic properties are found to change by thermal treatment as a result of the varied phase concentration, cation distribution and lattice parameters. Thus, the new synthesis route used in this study by applying EDTA as an organic precursor for preparing MgFe2O4 nanoparticles at rather low temperatures proved to be efficient in obtaining nanoparticles with favorable structural and magnetic properties. Such properties would qualify them for several potential applications including e.g. in hyperthermia treatment, as contrast agents in magnetic resonance imaging (MRI), and in ferroelastomers technology.

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

    PubMed

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

    2009-10-15

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

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

    PubMed Central

    Denadai, Ângelo 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

    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

  6. Effects of Thermal Annealing on Structural and Magnetic Properties of Lithium Ferrite Nanoparticles

    Microsoft Academic Search

    Natas?a G. Jovic?; Ahmad S. Masadeh; Aleksandar S. Kremenovic?; Bratislav V. Antic?; Jovan L. Blanusa; Nikola D. Cvjeticanin; Gerardo F. Goya; Marco Vittori Antisari; Emil S. Bozin

    2010-01-01

    Pure, crystalline, 10 nm lithium ferrite phase (Li{sub 0.5}Fe{sub 2.5}O), was successfully synthesized at very low temperature using a modified combustion method. The crystal structure and microstructure evolution of this system upon annealing were monitored by a careful investigation of X-ray diffractograms collected on a synchrotron source. Comparative analysis of the results obtained from the full profile Rietveld method (in

  7. Preparation and magnetic properties of hexagonal barium ferrite films using BaM nanoparticles

    Microsoft Academic Search

    Ali Ghasemi; Reza Shams Alam; Akimitsu Morisako

    2008-01-01

    Barium ferrite (BaFe12O19—BaM) thick films have been synthesized using a spinning coating sol–gel process. The coating sol was formed from BaM powders dispersed in the BaM raw sol. XRD, SEM, EDX, vibrating sample magnetometer (VSM), and ac susceptometer, were employed to evaluate the structure, composition and magnetic properties of BaM thick films. The results indicated that a uniform and crack-free

  8. Degradation of aqueous and soil-sorbed estradiol using a new class of stabilized manganese oxide nanoparticles.

    PubMed

    Han, Bing; Zhang, Man; Zhao, Dongye; Feng, Yucheng

    2015-03-01

    Manganese oxide (MnO2) was reported to be effective for degrading aqueous pharmaceutical chemicals. However, little is known about its potential use for degrading soil-sorbed contaminants. To bridge this knowledge gap, we synthesized, for the first time, a class of stabilized MnO2 nanoparticles using carboxymethyl celluloses (CMC) as a stabilizer, and tested their effectiveness for degrading aqueous and soil-sorbed estradiol. The most desired particles (highest reactivity and soil deliverability) were obtained at a CMC/MnO2 molar ratio of 1.39 × 10(-3), which yielded a mean hydrodynamic size of 39.5 nm and a narrow size distribution (SD = 0.8 nm). While non-stabilized MnO2 particles rapidly aggregated and were not transportable through a soil column, CMC-stabilized nanoparticles remained fully dispersed in water and were soil deliverable. At typical aquatic pH (6-7), CMC-stabilized MnO2 exhibited faster degradation kinetics for oxidation of 17?-estradiol than non-stabilized MnO2. The reactivity advantage becomes more evident when used for treating soil-sorbed estradiol owing to the ability of CMC to complex with metal ions and prevent the reactive sites from binding with inhibitive soil components. A retarded first-order rate model was able to interpret the oxidation kinetics for CMC-stabilized MnO2. When used for degrading soil-sorbed estradiol, several factors may inhibit the oxidation effectiveness, including desorption rate, soil-MnO2 interactions, and soil-released metals and reductants. CMC-stabilized MnO2 nanoparticles hold the potential for facilitating in situ oxidative degradation of various emerging contaminants in soil and groundwater. PMID:25543239

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

    Microsoft Academic Search

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

    2005-01-01

    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

  10. Heat capacity and thermodynamic functions of nanostructured manganese ferrites of composition NdMe1.5MnFeO6 (Me = Mg, Ca, Sr, and Ba) in the temperature range from 298.15 to 673 K

    NASA Astrophysics Data System (ADS)

    Kasenova, Sh. B.; Sagintaeva, Zh. I.; Kasenov, B. K.; Ermagambet, B. T.; Seisenova, A. A.; Kuanyshbekov, E. E.; Sherembaeva, R. T.

    2015-04-01

    The isobaric heat capacities of nanostructured manganese ferrites NdMe1.5MnFeO6, where Me is Mg, Ca, Sr, and Ba, are investigated at ? T ranging from 298.15 to 673 K by means of dynamic calorimetry. It is established that all of the investigated compounds exhibit ?-shape anomalies on dependence graphs C p ° ˜ ( T) that could be due to second-order phase transitions. Dependence equations C p ° ˜ ( T) are derived with allowance for the temperatures of phase transitions and the temperature dependences of their thermodynamic functions S°( T), H°( T) - H°(298.15), and ? xx ( T) are calculated for the temperature range of 298.15 to 675 K.

  11. Preparation of bismuth ferrite nanoparticles and their photocatalytic activity for MO degradation

    Microsoft Academic Search

    Man Zhang; Hua Yang; Tao Xian; Zhiqiang Wei; Wangjun Feng

    2011-01-01

    A modified polyacrylamide gel method was used to fabricate Bi2Fe4O9 nanoparticles. Thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) analysis, fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) were used in combination to investigate the thermal decomposition process of xerogels and the formation of Bi2Fe4O9 phase. It is demonstrated that high-phase-purity Bi2Fe4O9 nanoparticles can be prepared at a calcining temperature

  12. High magnetostriction and coupling coefficient for sintered cobalt ferrite derived from superparamagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Khaja Mohaideen, K.; Joy, P. A.

    2012-08-01

    High magnetostriction (?) and coupling coefficient (d? /dH) of 315 ppm and 1.97×10-9 A-1m, respectively, are obtained at room temperature for sintered cobalt ferrite derived from nanocrystalline powders. Also, the powder was compacted at a low pressure of 8 MPa and sintered for a short duration of 10 min at 1450 °C. Magnetic annealing at 300 °C in a field of 0.5 T for 30 min further enhanced the magnetostriction coefficient to 345 ppm with a higher coupling coefficient 2.12×10-9 A-1m. The magnetic field above which maximum magnetostriction is observed is reduced by almost half after magnetic annealing.

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

    PubMed

    Singh, Charanjit; Goyal, Ankita; Singhal, Sonal

    2014-07-21

    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

  14. ?(3) measurement and optical power limiting behavior of manganese doped lithium tetraborate nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohandoss, R.; Dhanuskodi, S.; Vinitha, G.

    2015-02-01

    Manganese doped Li2B4O7 nano crystallites were prepared by chemical method and characterized by XRD, FTIR, UV and fluorescence spectra. FESEM reveals that the particles are coagulated and the particle size is in the range of 50-107 nm. Bands appear at 682-769 cm-1corresponds to the bending of B-O linkage in borate network. Nonradiative energy transfer process is observed from fluorescence spectrum. UV-Vis studies show the samples are completely transparent in the visible region and having absorption peaks (234 and 276 nm) in UV regime. The measured second harmonic generation values are 0.9 times KDP. The nonlinear optical parameters such as nonlinear refractive index, n2 (10-8 cm2/W), nonlinear absorption, ? (10-2 cm/W) and nonlinear optical susceptibility, ?(3) (10-5 esu) are estimated using a Nd:YAG laser (532 nm, 50 mW).

  15. ?(3) measurement and optical power limiting behavior of manganese doped lithium tetraborate nanoparticles.

    PubMed

    Mohandoss, R; Dhanuskodi, S; Vinitha, G

    2015-02-01

    Manganese doped Li2B4O7 nano crystallites were prepared by chemical method and characterized by XRD, FTIR, UV and fluorescence spectra. FESEM reveals that the particles are coagulated and the particle size is in the range of 50-107 nm. Bands appear at 682-769 cm(-1) corresponds to the bending of B-O linkage in borate network. Nonradiative energy transfer process is observed from fluorescence spectrum. UV-Vis studies show the samples are completely transparent in the visible region and having absorption peaks (234 and 276 nm) in UV regime. The measured second harmonic generation values are 0.9 times KDP. The nonlinear optical parameters such as nonlinear refractive index, n2 (10(-8) cm(2)/W), nonlinear absorption, ? (10(-2) cm/W) and nonlinear optical susceptibility, ?(3) (10(-5) esu) are estimated using a Nd:YAG laser (532 nm, 50 mW). PMID:25459619

  16. Magnetic and structural properties of RE doped Co-ferrite (REåNd, Eu, and Gd) nano-particles synthesized by co-precipitation

    NASA Astrophysics Data System (ADS)

    Amiri, S.; Shokrollahi, H.

    2013-11-01

    Cobalt ferrite nano-particles, Co0.9RE0.1Fe2O4, with three different rare earth ions (Nd, Eu, and Gd) were prepared by the chemical co-precipitation method. X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), Fourier Transform Infrared (FTIR), and Vibrating Sample Magnetometry were carried out to study the structural and magnetic properties, respectively. The XRD results revealed that the crystal size is about 22 nm for Gd-Co ferrite, which is close to the particle sizes observed from TEM images (20 nm). The FTIR measurements between 350 and 4000 cm-1 confirmed the intrinsic cation vibrations of the spinel structure. The results showed that the RE ions increase both vibrational frequencies and bond strength. The magnetic results showed that the highest magnetic coercivity and the loop area correspond to the Gd-Co ferrite, making it suitable for hyperthermia treatment. Also, the Curie point was decreased by the RE ions and had its lowest value for Nd-Co ferrite (336 °C).

  17. Intragranular ferrite nucleation in medium-carbon vanadium steels

    Microsoft Academic Search

    Fusao Ishikawa; Toshihiko Takahashi; Tatsurou Ochi

    1994-01-01

    In this study, the mechanism of intragranular ferrite nucleation is investigated. It is found that “intragranular ferrite\\u000a idiomorphs” nucleate at vanadium nitrides which precipitate at manganese sulfide particles during cooling in the austenite\\u000a region. It is observed that intragranular ferrite has the Baker-Nutting orientation relationship with vanadium nitride which\\u000a precipitated at manganese sulfide. According to classical nucleation theory, the proeutectoid

  18. Understanding the role of gold nanoparticles in enhancing the catalytic activity of manganese oxides in water oxidation reactions.

    PubMed

    Kuo, Chung-Hao; Li, Weikun; Pahalagedara, Lakshitha; El-Sawy, Abdelhamid M; Kriz, David; Genz, Nina; Guild, Curtis; Ressler, Thorsten; Suib, Steven L; He, Jie

    2015-02-16

    The Earth-abundant and inexpensive manganese oxides (MnOx ) have emerged as an intriguing type of catalysts for the water oxidation reaction. However, the overall turnover frequencies of MnOx catalysts are still much lower than that of nanostructured IrO2 and RuO2 catalysts. Herein, we demonstrate that doping MnOx polymorphs with gold nanoparticles (AuNPs) can result in a strong enhancement of catalytic activity for the water oxidation reaction. It is observed that, for the first time, the catalytic activity of MnOx /AuNPs catalysts correlates strongly with the initial valence of the Mn centers. By promoting the formation of Mn(3+) species, a small amount of AuNPs (<5?%) in ?-MnO2 /AuNP catalysts significantly improved the catalytic activity up to 8.2 times in the photochemical and 6 times in the electrochemical system, compared with the activity of pure ?-MnO2 . PMID:25284796

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

    PubMed

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

    2011-09-01

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

  20. Plasma-assisted catalytic dry reforming of methane: Highly catalytic performance of nickel ferrite nanoparticles embedded in silica

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaogang; Tan, Shiyu; Dong, Lichun; Li, Shaobo; Chen, Hongmei

    2015-01-01

    Spinel nickel ferrite nanoparticles (NiFe2O4 NPs) embedded in silica (NiFe2O4#SiO2) was prepared to enhance the reaction performance of the dry reforming of methane in a coaxial dielectric barrier discharge reactor. NiFe2O4 NPs of around 10 nm were effectively embedded in porous SiO2 NPs (?100 nm in diameter). Compared to the supported Ni-based catalysts (Ni/?-Al2O3, Ni-Fe/?-Al2O3, Ni-Fe/SiO2, and NiFe2O4), the NiFe2O4#SiO2 catalyst placed at the discharge zone exhibited excellent catalytic performance and high resistance to carbon formation during dry reforming under ambient conditions without the involvement of extra heat. The synergetic effect between the non-thermal plasma and the NiFe2O4#SiO2 catalyst favored the conversion of CH4 and CO2 into syngas. The results indicated that the special structure of the as-synthesized NiFe2O4#SiO2 catalyst was capable of restraining the aggregation of Ni-Fe alloy and suppressing the carbon formation in the reforming process.

  1. Effects of Rare Earth Oxides on Some Physical Properties of Li-Zn Nanoparticle Ferrites

    NASA Astrophysics Data System (ADS)

    Ahmed, M. A.; Okasha, N.; Ali, A. I.; Hammam, M.; Song, J. Y.

    2011-06-01

    The spinel ferrite Li0.2Zn0.6LayFe2.2-yO4; 0.01 ? y ? 0.1 were prepared by the usual ceramic sintering technique. XRD confirmed the formation of the samples in single phase spinel structure for all the samples. The lattice parameters decreased with increasing the La-content. The d c resistivity was measured as a function of temperature. The obtained results indicate the semiconductor like behavior, where more than straight lines indicating the presence of different conductions mechanism exist. The density of states near Fremi level as a function of La-content and discussed based on the variable range hoping model. The dielectric constant and dielectric loss were measured as a function of temprature and frequency. The dispersion peak at low frequency (10 kHz) was splitted by increasing La-content up to the suggested absorber splitting.

  2. Experimental observations and nucleation and growth theory of polyhedral magnetic ferrite nanoparticles synthesized

    E-print Network

    McHenry, Michael E.

    functionalized form). Faceted magnetite nanoparticles (Fig. 1) have been observed in magnetotactic bacteria [10 in the magnetotactic bacteria does [15]. The truncated octahedral shapes are also the most commonly occurring] and in the Martian meteorite ALH84001 [11­13]. In the magnetotactic bacte- ria, nature selects magnetite particles

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

    PubMed

    Shi, Wenbing; Wang, Hui; Huang, Yuming

    2011-01-01

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

  4. Synergistic effect of manganese oxide nanoparticles and graphene nanosheets in composite anodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Luo, Shu; Yu, Yang; Li, Mengya; Wu, Hengcai; Zhao, Fei; Jiang, Kaili; Wang, Jiaping; Kang, Feiyu; Fan, Shoushan

    2015-01-01

    A graphene-Mn3O4-graphene (GMG) sandwich structure with homogeneous anchoring of Mn3O4 nanoparticles among flexible and conductive graphene nanosheets (GSs) is achieved through dispersion of the GSs in Mn(NO3)2 solution and subsequent calcination. Mn3O4 nanoparticles are 50 ˜ 200 nm clusters consisting of 10 ˜ 20 nm primary particles, and serve as spacers to prevent the re-stacking of the GSs. GSs provide a highly conductive network among Mn3O4 nanoparticles for efficient electron transfer and buffer any volume change during cycling. Due to the strong synergistic effect between Mn3O4 and GSs, the capacity contributions from GSs and Mn3O4 in GMG are much larger than capacities of pure GSs and Mn3O4. Consequently, the GMG composite electrodes show excellent electrochemical properties for lithium ion battery applications, demonstrating a large reversible capacity of 750 mAh g?1 at 0.1 C based on the mass of GMG with no capacity fading after 100 cycles, and high rate abilities of 500 mAh g?1 at 5 C and 380 mAh g?1 at 10 C.

  5. Effect of light on the magnetic properties of cobalt ferrite nanoparticles

    Microsoft Academic Search

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

    2000-01-01

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

  6. Biodiesel synthesis catalyzed by transition metal oxides: ferric-manganese doped tungstated/molybdena nanoparticle catalyst.

    PubMed

    Alhassan, Fatah Hamid; Rashid, Umer; Taufiq-Yap, Yun Hin

    2015-01-01

    The solid acid Ferric-manganese doped tungstated/molybdena nananoparticle catalyst was prepared via impregnation reaction followed by calcination at 600°C for 3 h. The characterization was done using X-ray diffraction (XRD), Raman spectroscopy, thermal gravimetric analysis (TGA), temperature programmed desorption of NH3 (TPD-NH3), X-ray fluorescence (XRF), Transmission electron microscope (TEM) and Brunner-Emmett-Teller surface area measurement (BET). Moreover, dependence of biodiesel yield on the reaction variables such as the reaction temperature, catalyst loading, as well as molar ratio of methanol/oil and reusability were also appraised. The catalyst was reused six times without any loss in activity with maximum yield of 92.3% ±1.12 achieved in the optimized conditions of reaction temperature of 200°C; stirring speed of 600 rpm, 1:25 molar ratio of oil to alcohol, 6 % w/w catalyst loading as well as 8 h as time of the reaction. The fuel properties of WCOME's were evaluated, including the density, kinematic viscosity, pour point, cloud point and flash point whereas all properties were compared with the limits in the ASTM D6751 standard. PMID:25492234

  7. Mn2+, Ti4+ substituted barium ferrite

    Microsoft Academic Search

    G. Turilli; F. Licci; S. Rinaldi; A. Deriu

    1986-01-01

    The substitution of iron by manganese in M-type barium ferrite BaFe12O19 has been investigated with the aim of elucidating its effect on the magnetic and magnetostrictive properties. Substitution of up to 0.4 manganese atoms per unit formula did not affect the magnetization whilst the anisotropy and magnetostriction decreased by 30% and 20%, respectively. Higher manganese contents gave rise to large

  8. Mineral of the month: manganese

    USGS Publications Warehouse

    Corathers, Lisa

    2005-01-01

    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.

  9. Photocatalytic activities of multiferroic bismuth ferrite nanoparticles prepared by glycol-based sol–gel process

    Microsoft Academic Search

    X. WangY; Y. Lin; Z. C. Zhang; J. Y. Bian

    The uniform multiferroic BiFeO3 nanoparticles with fairly narrow particle size distribution have been successfully synthesized by a simple glycol-based sol–gel\\u000a route at relatively low temperature. The thus-prepared powders were characterized by X-ray diffractometry (XRD), thermogravimetric\\u000a and differential thermal analysis (DTA\\/TG), and transmission electron microscopy (TEM). Rapid sintering and subsequently quenching\\u000a to room temperature are the two vital important factors for

  10. Artificial neural network modelling of photodegradation in suspension of manganese doped zinc oxide nanoparticles under visible-light irradiation.

    PubMed

    Abdollahi, Yadollah; Zakaria, Azmi; Sairi, Nor Asrina; Matori, Khamirul Amin; Masoumi, Hamid Reza Fard; Sadrolhosseini, Amir Reza; Jahangirian, Hossein

    2014-01-01

    The artificial neural network (ANN) modeling of m-cresol photodegradation was carried out for determination of the optimum and importance values of the effective variables to achieve the maximum efficiency. The photodegradation was carried out in the suspension of synthesized manganese doped ZnO nanoparticles under visible-light irradiation. The input considered effective variables of the photodegradation were irradiation time, pH, photocatalyst amount, and concentration of m-cresol while the efficiency was the only response as output. The performed experiments were designed into three data sets such as training, testing, and validation that were randomly splitted by the software's option. To obtain the optimum topologies, ANN was trained by quick propagation (QP), Incremental Back Propagation (IBP), Batch Back Propagation (BBP), and Levenberg-Marquardt (LM) algorithms for testing data set. The topologies were determined by the indicator of minimized root mean squared error (RMSE) for each algorithm. According to the indicator, the QP-4-8-1, IBP-4-15-1, BBP-4-6-1, and LM-4-10-1 were selected as the optimized topologies. Among the topologies, QP-4-8-1 has presented the minimum RMSE and absolute average deviation as well as maximum R-squared. Therefore, QP-4-8-1 was selected as final model for validation test and navigation of the process. The model was used for determination of the optimum values of the effective variables by a few three-dimensional plots. The optimum points of the variables were confirmed by further validated experiments. Moreover, the model predicted the relative importance of the variables which showed none of them was neglectable in this work. PMID:25538962

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

    PubMed Central

    2012-01-01

    The optimization processes of photo degradation are complicated and expensive when it is performed with traditional methods such as one variable at a time. In this research, the condition of ortho-cresol (o-cresol) photo degradation was optimized by using a semi empirical method. First of all, the experiments were designed with four effective factors including irradiation time, pH, photo catalyst’s amount, o-cresol concentration and photo degradation % as response by response surface methodology (RSM). The RSM used central composite design (CCD) method consists of 30 runs to obtain the actual responses. The actual responses were fitted with the second order algebraic polynomial equation to select a model (suggested model). The suggested model was validated by a few numbers of excellent statistical evidences in analysis of variance (ANOVA). The used evidences include high F-value (143.12), very low P-value (<0.0001), non-significant lack of fit, the determination coefficient (R2?=?0.99) and the adequate precision (47.067). To visualize the optimum, the validated model simulated the condition of variables and response (photo degradation %) be using a few number of three dimensional plots (3D). To confirm the model, the optimums were performed in laboratory. The results of performed experiments were quite close to the predicted values. In conclusion, the study indicated that the model is successful to simulate the optimum condition of o-cresol photo degradation under visible-light irradiation by manganese doped ZnO nanoparticles. PMID:22909072

  12. Artificial Neural Network Modelling of Photodegradation in Suspension of Manganese Doped Zinc Oxide Nanoparticles under Visible-Light Irradiation

    PubMed Central

    Abdollahi, Yadollah; Sairi, Nor Asrina; Amin Matori, Khamirul; Fard Masoumi, Hamid Reza

    2014-01-01

    The artificial neural network (ANN) modeling of m-cresol photodegradation was carried out for determination of the optimum and importance values of the effective variables to achieve the maximum efficiency. The photodegradation was carried out in the suspension of synthesized manganese doped ZnO nanoparticles under visible-light irradiation. The input considered effective variables of the photodegradation were irradiation time, pH, photocatalyst amount, and concentration of m-cresol while the efficiency was the only response as output. The performed experiments were designed into three data sets such as training, testing, and validation that were randomly splitted by the software's option. To obtain the optimum topologies, ANN was trained by quick propagation (QP), Incremental Back Propagation (IBP), Batch Back Propagation (BBP), and Levenberg-Marquardt (LM) algorithms for testing data set. The topologies were determined by the indicator of minimized root mean squared error (RMSE) for each algorithm. According to the indicator, the QP-4-8-1, IBP-4-15-1, BBP-4-6-1, and LM-4-10-1 were selected as the optimized topologies. Among the topologies, QP-4-8-1 has presented the minimum RMSE and absolute average deviation as well as maximum R-squared. Therefore, QP-4-8-1 was selected as final model for validation test and navigation of the process. The model was used for determination of the optimum values of the effective variables by a few three-dimensional plots. The optimum points of the variables were confirmed by further validated experiments. Moreover, the model predicted the relative importance of the variables which showed none of them was neglectable in this work. PMID:25538962

  13. RESEARCH Open Access Predictive Toxicology of cobalt ferrite

    E-print Network

    Paris-Sud XI, Université de

    RESEARCH Open Access Predictive Toxicology of cobalt ferrite nanoparticles: comparative in Korenstein1* Abstract Background: Cobalt-ferrite nanoparticles (Co-Fe NPs) are attractive for nanotechnology that oxidative stress is one possible mechanism for the toxicity of Co-Fe NPs. Keywords: Nanotoxicology, Cobalt-ferrite

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

    NASA Astrophysics Data System (ADS)

    Francis, Nicholas; Hedden, Morgan; Constantin, Costel

    2013-03-01

    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).

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

    PubMed Central

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

    2013-01-01

    Mn-based nanoparticles (NPs) have emerged as new class of probes for magnetic resonance imaging due to the impressive contrast ability. However, the reported Mn-based NPs possess low relaxivity and there are no immunotoxicity data regarding Mn-based NPs as contrast agents. Here, we demonstrate the ultrahigh relaxivity of water protons of 8.26?mM?1s?1 from the Mn3O4 NPs synthesized by a simple and green technique, which is twice higher than that of commercial gadolinium (Gd)-based contrast agents (4.11?mM?1s?1) and the highest value reported to date for Mn-based NPs. We for the first time demonstrate these Mn3O4 NPs biocompatibilities both in vitro and in vivo are satisfactory based on systematical studies of the intrinsic toxicity including cell viability of human nasopharyngeal carcinoma cells, normal nasopharyngeal epithelium, apoptosis in cells and in vivo immunotoxicity. These findings pave the way for the practical clinical diagnosis of Mn based NPs as safe probes for in vivo imaging. PMID:24305731

  16. Effect of manganese doping on the photoluminescence characteristics of chemically synthesized zinc sulfide nanoparticles

    NASA Astrophysics Data System (ADS)

    Kole, A. K.; Kumbhakar, P.

    2012-03-01

    The studies on luminescent II-VI semiconducting nanomaterials have attracted widespread attention recently, due to their potential applications in optoelectronic and biophotonic devices. Amongst other II-VI semiconductor nanoparticles (NPs), Mn2+-doped ZnS NPs having large exciton binding energy and wide direct band gap at room temperature have drawn considerable attention for exploring its interesting optical properties. However, in this report, water-soluble Mn2+-doped ZnS (ZnS:Mn) NPs with Mn2+ concentration varying between 1.5 and 5% (wt%) have been synthesized by chemical co-precipitation method at room temperature. X-ray diffraction (XRD) studies and the analysis of the selected area electron diffraction (SAED) pattern, obtained from transmission electron microscopy (TEM), confirmed the formation of zinc blende structure in all the synthesized samples. The particle sizes of the samples, as obtained from the optical absorption studies, varies between 2.2 and 2.7 nm with the increase of Mn2+ concentration between 1.5 and 5%. The room temperature photoluminescence (PL) emission measurements revealed the presence of yellow-orange emission band in all the Mn2+-doped samples which is attributed to Mn incorporation in ZnS. The Gaussian fittings of the measured PL spectra of all the samples show the presence of four PL peaks. Amongst the four PL peaks three peaks appeared at 445, 476, and 520 nm in all the samples but the fourth yellow-orange emission peak suffered a red shift from 593 to 600 nm with increasing Mn2+ concentration from 1.5 to 5%. In this report no quenching of yellow-orange emission peak is observed up to 5% Mn2+ doping concentration in ZnS. The synthesized water-soluble ZnS:Mn NPs can be further functionalized for using them as biolabels.

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

    PubMed

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  19. Magnetic properties of Co1-xZnxFe2O4 spinel ferrite nanoparticles synthesized by starch-assisted sol-gel autocombustion method and its ball milling

    NASA Astrophysics Data System (ADS)

    Yadav, Raghvendra Singh; Havlica, Jaromir; Hnatko, Miroslav; Šajgalík, Pavol; Alexander, Cigá?; Palou, Martin; Bartoní?ková, Eva; Bohá?, Martin; Frajkorová, Františka; Masilko, Jiri; Zmrzlý, Martin; Kalina, Lukas; Hajdúchová, Miroslava; Enev, Vojt?ch

    2015-03-01

    In this article, Co1-xZnxFe2O4 (x=0.0 and 0.5) spinel ferrite nanoparticles were achieved at 800 °C by starch-assisted sol-gel autocombustion method. To further reduce the particle size, these synthesized ferrite nanoparticles were ball-milled for 2 h. X-ray diffraction patterns demonstrated single phase formation of Co1-xZnxFe2O4 (x=0.0 and 0.5) spinel ferrite nanoparticles. FE-SEM analysis indicated the nanosized spherical particles formation with spherical morphology. The change in Raman modes and relative intensity were observed due to ball milling and consequently decrease of particle size and cationic redistribution. An X-ray Photoelectron Spectroscopy (XPS) result indicated that Co2+, Zn2+ and Fe3+ exist in octahedral and tetrahedral sites. The cationic redistribution of Zn2+ and consequently Fe3+ occurred between octahedral and tetrahedral sites after ball-milling. The change in saturation magnetization (Ms) and coercivity (Hc) with decrease of nanocrystalline size and distribution of cations in spinel ferrite were observed.

  20. Interrogation of CoxZnyNizFe2O4 ferrite nanoparticles for insight into specific power loss for medical hyperthermia

    NASA Astrophysics Data System (ADS)

    Jagoo, Zafrullah; Kozlowski, Gregory; Turgut, Zafer; Rebrov, Evgeny

    2012-04-01

    Magnetic nanoparticles (MNPs) have shown to be viable candidates as heat sources for magnetic hyperthermia under an alternating magnetic field. The present work investigates heating characteristics of sol-gel processed ferro-magnetic CoxZnyNizFe2O4 (ferrite) nanoparticles with different magnetic properties. The nanoparticles were irradiated by a radio-frequency magnetic field through a 5-turns coil using a 1.2 kW heating system with variable frequency in the 295-315 kHz range and a maximum current output of 100 A. Higher specific power losses were measured for nanoparticles that had lower coercivities. The advantage of having a high specific power loss for clinical applications is that a minute amount of nanoparticle has to be introduced in the body to adequately destroy malignant tumor cells.[4pt] |c|c|c|c|c|c| Name & Grain Size & Mr & Ms & Hc & SPL100A&(nm) & (emu/g) & (emu/g) & (Oe) & (W/g^2)Ni0.5Zn0.5Fe2O4 & 48.7 & 2.85 & 47.5 & 42.2 & 84 ± 2Co0.4Ni0.4Zn0.2Fe2O4 & 46 & 3.29 & 26.2 & 75.3 & 28 ± 3NiFe2O4 & 42.9 & 3.47 & 14.8 & 146 & 17.0 ± 0.5CoFe2O4 & 34.5 & 7.01 & 22.2 & 626 & 0.64 ± 0.05

  1. Magnetic properties of hexagonal strontium ferrite thick film synthesized by sol-gel processing using SrM nanoparticles

    NASA Astrophysics Data System (ADS)

    Ghasemi, Ali; Morisako, Akimitsu; Liu, Xiaoxi

    Strontium ferrite SrFe 12O 19 (SrM) thick films have been synthesized using a spinning coating sol-gel process. The coating sol was formed from SrFe 12O 19 powders dispersed in the strontium ferrite raw sol. XRD, TEM, SEM, vibrating sample magnetometer (VSM) and ac susceptometer were employed to evaluate the structure, composition and magnetic properties of SrFe 12O 19 thick films. The results indicated that a uniform and crack-free coating of Strontium ferrite with ˜15 ?m thickness can be produced with a good deal of consistency. The magnetization hysteresis loops were almost the same for magnetic fields both applied in parallel and perpendicular.

  2. 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)

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

    2010-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  4. Investigating the Characteristics of Cobalt-Substituted MnZn Ferrites by Equivalent Electrical Elements

    Microsoft Academic Search

    Tsorng-Juu Liang; Hsiau-Hsian Nien; Jiann-Fuh Chen

    2007-01-01

    We investigated the electrical and magnetic properties of cobalt-substituted manganese-zinc soft ferrite by using the equivalent lumped elements acquired from the appropriate equivalent electrical circuit of polycrystalline ferrite. We applied the equivalent lumped circuit, combined with equivalent lumped resistances and capacitance, to determine the effect of microstructure on electrical and magnetic properties of cobalt-substituted manganese-zinc ferrites. Both the hysteresis loss

  5. Synthesis of cobalt ferrite (CoFe2O4) nanoparticles using combustion, coprecipitation, and precipitation methods: A comparison study of size, structural, and magnetic properties

    NASA Astrophysics Data System (ADS)

    Houshiar, Mahboubeh; Zebhi, Fatemeh; Razi, Zahra Jafari; Alidoust, Ali; Askari, Zohreh

    2014-12-01

    In this work the cobalt ferrite (CoFe2O4) nanoparticles are synthesized using three different methods; combustion, coprecipitation, and precipitation. Size, structural, and magnetic properties were determined and compared using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). XRD data analysis showed an average size of 69.5 nm for combustion, 49.5 nm for coprecipitation, and 34.7 nm for precipitation samples which concorded with SEM images. XRD data further revealed a reverse cubic spinel structure with the space group Fd-3m in all three samples. VSM data of samples showed a saturation point in the magnetic field of less than 15 kOe. Magnetization saturation (Ms) was 56.7 emu/g for combustion synthestized samples, 55.8 emu/g for coprecipitation samples, and 47.2 emu/g for precipitation samples. Coercivity (Hc) was 2002 Oe for combustion synthestized samples, 850 Oe for coprecipitation samples, and 233 Oe for precipitation samples. These results show that various methods of nanoparticle synthesis can lead to different particle sizes and magnetic properties. Hc and Ms are greatest in the combustion method and least in precipitation method.

  6. Manganese Intoxication

    PubMed Central

    Hine, Charles H.; Pasi, Aurelio

    1975-01-01

    We have reported two cases of chronic manganese poisoning. Case 1 followed exposure to manganese fumes in cutting and burning manganese steel. Case 2 resulted from exposure to dusts of manganese dioxide, an ingredient used in glazing of ceramics. There were initial difficulties in establishing the correct diagnosis. Prominent clinical features were severe and persistent chronic depressive psychosis (Case 1), transient acute brain syndrome (Case 2) and the presence of various extrapyramidal symptoms in both cases. Manganese intoxication has not previously been reported as occurring in California. With increasing use of the metal, the disease should be considered in the differential diagnosis of neurologic and psychiatric disease. Our observations were made in the period 1964 through 1968. Recently the prognosis of victims of manganese poisoning has been improved dramatically by the introduction of levodopa as a therapeutic agent. PMID:1179714

  7. Hot coal gas desulfurization with manganese-based sorbents

    SciTech Connect

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

    1994-12-01

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

  8. Magnetooptics and magnetic ordering in ferrite nanoparticles in glass doped with iron and rare-earth elements

    Microsoft Academic Search

    O. S. Ivanova; I. S. Edelman; R. D. Ivantsov; V. N. Zabluda; S. A. Stepanov; S. M. Zharkov; G. M. Zeer; Ya. V. Zubavichus; A. A. Veligzhanin; J. Curely

    2011-01-01

    Magnetic circular dichroism and X-ray diffraction were used to investigate the structure and magnetooptical properties of\\u000a nanoparticles formed in potassium-aluminum-germanium-boron glass doped with iron and rare-earth elements. It is demonstrated\\u000a that in thermally processed glass, the main magnetic phase of the formed nanoparticles is ?-Fe2O3 maghemite.

  9. Magnetic and optical properties of multiferroic bismuth ferrite nanoparticles by tartaric acid-assisted sol–gel strategy

    Microsoft Academic Search

    Xiong Wang; Yan'ge Zhang; Zhibin Wu

    2010-01-01

    Pure BiFeO3 nanoparticles have been successfully synthesized through the tartaric acid-assisted sol–gel method at relatively low temperature. The as-prepared nanoparticles were characterized by a variety of techniques. The success in preparing pure BiFeO3 may be attributed to the formation of heterometallic polynuclear complexes in the tartaric acid system. The ferroelectric phase transition (TC=851°C) was determined, revealing the ferroelectric nature of

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

    PubMed Central

    2012-01-01

    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

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

    Microsoft Academic Search

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

    2009-01-01

    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

  12. Role of interparticle interactions on the magnetic behavior of Mg(0.95)Mn(0.05)Fe(2)O(4) ferrite nanoparticles.

    PubMed

    Sharma, S K; Kumar, Ravi; Kumar, Shalendra; Knobel, M; Meneses, C T; Siva Kumar, V V; Reddy, V R; Singh, M; Lee, C G

    2008-06-11

    We present here a detailed investigation of the static and dynamic magnetic behavior of a Mg(0.95)Mn(0.05)Fe(2)O(4) spinel ferrite nanoparticle system synthesized by high-energy ball milling of almost identical particle size distributions ([Formula: see text], 5.1 and 6.0 ± 0.6 nm). The samples were characterized by using x-ray diffraction, Mössbauer spectroscopy, dc magnetization and frequency dependent real ?(')(T) and imaginary ?('')(T) parts of ac susceptibility measurements. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization have been recorded in a low field and show a behavior typical of superparamagnetic particles above a temperature of 185 ± 5 K, which is further supported from the temperature dependent Mössbauer measurements. The fact that the blocking temperature calculated from the ZFC magnetization and Mössbauer data are almost similar gives a clear indication of the interparticle interactions among these nanoparticle systems. This is further supported from the FC magnetization curves, which are almost flat below a certain temperature (less than the blocking temperature), as compared with the monotonically increasing behavior characteristics of non-interacting superparamagnetic particles. A shift of the blocking temperature with increasing frequency was observed in the real ?(')(T) and imaginary ?('')(T) parts of the ac susceptibility measurements. The analysis of the results shows that the data fit well with the Vogel-Fulcher law, whereas trials using the Neel-Brown and power law are unproductive. The role of magnetic interparticle interactions on the magnetic behavior, namely superparamagnetic relaxation time and magnetic anisotropy, are discussed. PMID:21694305

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

    PubMed

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

    2012-08-01

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

  14. Novel silver nanoparticle-manganese oxyhydroxide-graphene oxide nanocomposite prepared by modified silver mirror reaction and its application for electrochemical sensing.

    PubMed

    Bai, Wushuang; Nie, Fei; Zheng, Jianbin; Sheng, Qinglin

    2014-04-23

    A gas/liquid interface will be formed when the free volatilized methyl aldehyde gas begins to dissolve in to solution. On the basis of the traditional silver mirror reaction, silver nanoparticle-manganese oxyhydroxide-graphene oxide (Ag-MnOOH-GO) nanocomposite was synthesized at the gas/liquid interface without any protection of inert gas at room temprature. The morphology of the nanocomposites could be controlled by adjusting the reaction temperature and time. The morphology and composition of the nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The composites were then applied for electrochemical sensing. The electrochemical investigation for the sensor indicates that it has excellent property to catalyze H2O2, and could detect H2O2 with a low detection limit of 0.2?M and wide linear range of 0.5 ?M to 17.8 mM. The present study provides a general platform for the controlled synthesis of nanomaterials and can be extended to other optical, electronic, and magnetic nanocompounds. PMID:24660983

  15. pH-Responsive Iron Manganese Silicate Nanoparticles as T1-T2* Dual-Modal Imaging Probes for Tumor Diagnosis.

    PubMed

    Chen, Jian; Zhang, Wei-Jie; Guo, Zhen; Wang, Hai-Bao; Wang, Dong-Dong; Zhou, Jia-Jia; Chen, Qian-Wang

    2015-03-11

    Magnetic resonance imaging (MRI) probes can be concentrated in tumors through grafting targeting agents. However, the clinical application of such targeted MRI probes is largely limited because specific agents are only used to target specific characteristics of cancer cells. The development of the MRI probes that can be used regardless of tumor types or their developmental stages is highly appreciated. The acidic tumor microenvironments and acidic organelles (endosomes/lysosomes) in cancer cells are universal phenomena of solid tumors, and nanoparticles can also accumulate in tumor tissues by enhanced permeability and retention (EPR) effect. Here, we reported the synthesis of pH-responsive T1-T2* dual-modal contrast agents based on iron manganese silicate (FeMn(SiO4)) hollow nanospheres, which can release Mn(2+) ions in acidic environments, exhibiting excellent ability as agents for magnetic resonance and red fluorescence imaging. MRI for mouse models revealed that the nanoprobes could accumulate in tumors via EPR effect and then distinguish tumors from normal tissues with the synergistic effect of T1 and T2* signal only 10 min after intravenous injection. Fluorescence imaging demonstrated that the nanoprobes could be endocytosed into cancer cells and located at their lower pH compartments. Moreover, the hollow nanospheres showed no obvious toxicity and inflammation to the major organs of mice, which made them attractive diagnostic agents for different types of cancers. PMID:25685956

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

    E-print Network

    Laughlin, David E.

    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

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

    SciTech Connect

    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

    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.

  18. Enrichment of magnetic alignment stimulated by ?-radiation in core-shell type nanoparticle Mn-Zn ferrite

    NASA Astrophysics Data System (ADS)

    Naik, P. P.; Tangsali, R. B.; Sonaye, B.; Sugur, S.

    2013-02-01

    Core shell type nanoparticle MnxZn1-xFe2O4 systems with x=0.55, 0.65 & 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 ?-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 Co60 source for different time intervals.

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

    Microsoft Academic Search

    Baharak Hosseinkhani; Giti Emtiazi

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  1. X-ray absorption spectra and X-ray magnetic circular dichroism studies at Fe and Co L 2,3 edges of mixed cobalt–zinc ferrite nanoparticles: cationic repartition, magnetic structure and hysteresis cycles

    Microsoft Academic Search

    J. F Hochepied; Ph Sainctavit; M. P Pileni

    2001-01-01

    X-ray absorption spectra (XAS) and X-ray magnetic circular dichroism (XMCD) spectra at Co and Fe L2,3 edges are performed on mixed cobalt–zinc ferrite nanoparticles Co0.73yZn0.73(1?y)Fe2.18?0.09 O4 (with y=0.4, 2.8 and 3.7nm average diameter; the symbol ? represents a vacancy). Simulation of the spectra thanks to ligand field multiplet theory allows an evaluation of the cationic repartition. Co2+ occupies preferentially octahedral

  2. Acid-degradable Core-shell Nanoparticles for Reversed Tamoxifen-resistance in Breast Cancer by Silencing Manganese Superoxide Dismutase (MnSOD)

    PubMed Central

    Cho, Soo Kyung; Pedram, Ali; Levin, Ellis R.; Kwon, Young Jik

    2013-01-01

    Drug resistance acquired by cancer cells is a significant challenge in the clinic and requires impairing the responsible pathological pathway. Administering chemotherapeutics along with silencing resistance-basis activity using RNA interference (RNAi) is expected to restore the activity of the chemotherapeutic. generate synergistic cancer eradication. This study attempted to reverse tamoxifen (TAM)-resistance in breast cancer by silencing a mitochondrial enzyme, manganese superoxide dismutase (MnSOD), which dismutates TAM-induced reactive oxygen species (ROS) (i.e., superoxide) to less harmful hydrogen peroxide and hampers therapeutic effects. Breast cancer cells were co-treated with TAM and MnSOD siRNA-delivering nanoparticles (NPs) made of a siRNA/poly(amidoamine) (PAMAM) dendriplex core and an acid-degradable polyketal (PK) shell. The (siRNA/PAMAM)-PK NPs were designed for the PK shell to shield siRNA from nucleases, minimize detrimental aggregation in serum, and facilitate cytosolic release of siRNA from endosomal compartments. This method of forming the PK shell around the siRNA/PAMAM core via surface-initiated photo-polymerization enables ease of tuning NPs’ size for readily controlled siRNA release kinetics. The resulting NPs were notably homogenous in size, resistant to aggregation in serum, and invulnerable to heparan sulfate-mediated disassembly, compared to siRNA/PAMAM dendriplexes. Gel electrophoresis and confocal microscopy confirmed efficient siRNA release from the (siRNA/PAMAM)-PK NPs upon stimuli-responsive hydrolysis of the PK shell. Sensitization of TAM-resistant MCF7-BK-TR breast cancer cells with (MnSOD siRNA/PAMAM)-PK NPs restored TAM-induced cellular apoptosis in vitro and significantly suppressed tumor growth in vivo, as confirmed by biochemical assays and histological observations. This study implies that combined gene silencing and chemotherapy is a promising strategy to overcoming a significant challenge in cancer therapy. PMID:24055523

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  4. Structural, optical and magnetic properties of chromium and manganese co-doped SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Subramanyam, K.; Sreelekha, N.; Amaranatha Reddy, D.; Murali, G.; Poornaprakash, B.; Ramu, S.; Vijayalakshmi, R. P.

    2015-01-01

    The rutile phase Sn0.99-xMnxCr0.01O2 (x = 0.00, 0.01, 0.03, 0.05 and 0.07) nanoparticles were synthesized by facile chemical co-precipitation method using poly ethylene glycol (PEG) as a capping agent. The samples were characterized by EDAX to confirm the expected stoichiometry. The X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy analyses of these samples showed the formation of impurity free crystals with a single phase rutile type tetragonal crystal structure as that of (P42/mnm) of SnO2. Optical absorption spectra and corresponding Tauc's plots showed a redshift of the absorption edge in SnO2 after being co-doped with Cr and Mn. The samples were examined for its magnetic property using vibrating sample magnetometer which indicated that transition of magnetic signals from ferromagnetic to the paramagnetic nature with inclusion of Mn content in SnO2: Cr host matrix. The observed magnetic behavior is well supported with the bound magnetic polarons (BMPs) model.

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

    PubMed

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

    2014-05-27

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

  6. Physica B 327 (2003) 382384 Synthesis of cobalt ferrite nanocrystallites by the forced

    E-print Network

    Spinu, Leonard

    2003-01-01

    Physica B 327 (2003) 382­384 Synthesis of cobalt ferrite nanocrystallites by the forced hydrolysis Research Institute-AMRI, University of New Orleans, New Orleans, USA Abstract Cobalt ferrite powder has]. This work is a study of the cobalt ferrite nanoparticles synthesized by this method. The synthesis of CoFe2O

  7. Magnetic properties of ultrafine cobalt ferrite particles L. D. Tung,a)

    E-print Network

    Spinu, Leonard

    Magnetic properties of ultrafine cobalt ferrite particles L. D. Tung,a) V. Kolesnichenko, D of a diluted system of ultrafine cobalt ferrite nanoparticles (d 3.3 nm). From the peak of the zero for cobalt ferrite, at 2 K, the reduced remanence Mr /Ms is equal to 0.46 which is close to the theoretical

  8. Sustainable synthesis of monodispersed spinel nano-ferrites

    EPA Science Inventory

    A sustainable approach for the synthesis of various monodispersed spinel ferrite nanoparticles has been developed that occurs at water-toluene interface under both conventional and microwave hydrothermal conditions. This general synthesis procedure utilizes readily available and ...

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

    NASA Astrophysics Data System (ADS)

    Espinal, Laura

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

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

    PubMed Central

    2013-01-01

    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

  11. Magnetic field directed assembly of superstructures of ferrite-ferroelectric core-shell nanoparticles and studies on magneto-electric interactions

    NASA Astrophysics Data System (ADS)

    Srinivasan, G.; Sreenivasulu, G.; Benoit, Crystal; Petrov, V. M.; Chavez, F.

    2015-05-01

    Composites of ferromagnetic and ferroelectric are of interest for studies on mechanical strain mediated magneto-electric (ME) interactions and for useful technologies. Here, we report on magnetic-field-assisted-assembly of barium titanate (BTO)-nickel ferrite (NFO) core-shell particles into linear chains and 2D/3D arrays and measurements of ME effects in such assemblies. First, we synthesized the core-shell nano-particles with 50-600 nm BTO and 10-200 nm NFO by chemical self-assembly by coating the ferroic particles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst via the "click" reaction. The core-shell structure was confirmed with electron microscopy and scanning probe microscopy. We obtained superstructure of the core-shell particles by subjecting them to a magnetic field gradient that exerts an attractive force on the particles and align them toward the regions of high field strengths. At low particle concentration, linear chains were formed and they evolved into 2D and 3D arrays at high particle concentrations. Magnetoelectric characterization on unassembled films and assembled arrays has been performed through measurements of low-frequency ME voltage coefficient (MEVC) by subjecting the sample to a bias magnetic field and an ac magnetic field. The MEVC is higher for field-assembled samples than for unassembled films and is found to be sensitive to field orientation with a higher MEVC for magnetic fields parallel to the array direction than for magnetic fields perpendicular to the array. A maximum MEVC of 20 mV/cm Oe, one of the highest reported for any bulk nanocomposite, is measured across the array thickness. A model is provided for ME coupling in the superstructures of BTO-NFO particulate composites. First, we estimated the MEVC for a free-standing BTO-NFO core-shell particle and then extended the model to include an array of linear chains of the particles. The theoretical estimates are in qualitative agreement with the data.

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

    PubMed

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

    2013-01-01

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

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

    PubMed

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

    2009-11-18

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

  14. Preparation of single-crystal copper ferrite nanorods and nanodisks

    SciTech Connect

    Du Jimin [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China); Liu Zhimin [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China)]. E-mail: liuzm@iccas.ac.cn; Wu Weize [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China); Li Zhonghao [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China); Han Buxing [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China)]. E-mail: hanbx@iccas.ac.cn; Huang Ying [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China)

    2005-06-15

    This article, for the first time, reports the preparation of single-crystal copper ferrite nanorods and nanodisks. Using amorphous copper ferrite nanoparticles synthesized by reverse micelle as reaction precursor, single-crystal copper ferrite nanorods were synthesized via hydrothermal method in the presence of surfactant polyethylene glycol (PEG), however, copper ferrite nanodisks were prepared through the same procedures except the surfactant PEG. The resulting nanomaterials have been characterized by powder X-ray diffraction (XRD), selected electron area diffraction (SEAD), and transmission electron microscopy (TEM). The bulk composition of the samples was determined by means of X-ray photoelectron spectroscopy (XPS)

  15. Mn substituted cobalt ferrites (CoMnxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0)): As magnetically separable heterogeneous nanocatalyst for the reduction of nitrophenols

    NASA Astrophysics Data System (ADS)

    Goyal, Ankita; Bansal, S.; Kumar, V.; Singh, Jagdish; Singhal, Sonal

    2015-01-01

    Manganese substituted cobalt ferrite nanoparticles with composition CoMnxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were synthesized using sol-gel technology and characterized using the Fourier transform infrared spectroscopy, high resolution transmission electron microscopy and X-ray diffraction techniques to confirm their formation. The prepared ferrite samples were explored as catalysts for the reduction of nitrophenols in the presence of NaBH4 as reducing agent. Pure cobalt ferrite was found to be inactive. However, catalytic efficiency enhanced dramatically with the introduction of Mn ions into the catalytically active surface sites (octahedral sites) of the cobalt ferrite lattice. This could be due to the presence of synergistic effect between the Co3+, Mn3+ and Fe3+ ions present in the octahedral sites. CoMn02Fe1.8O4 ferrite was observed to have the best catalytic activity for the reduction of nitrophenols because of the highest Fe3+/Mn3+ and Co3+/Mn3+ ionic ratio at the catalytically active octahedral sites. The kinetics of reduction was studied and the reduction reaction followed pseudo first order kinetics. The rates of reduction of the three isomers of nitrophenols followed the order - 2-nitrophenol > 4-nitrophenol > 3-nitrophenol.

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

    SciTech Connect

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

    1994-11-01

    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.

  17. Angle dependence of the ferromagnetic resonance linewidth in easy-axis and easy-plane single crystal hexagonal ferrite disks

    E-print Network

    Patton, Carl

    - magnetic resonance linewidth measurements of single crystal barium ferrite Ba-M indicate that these losses crystal hexagonal ferrite disks M. J. Hurben,a) D. R. Franklin,b) and C. E. Patton Department of Physics angle for c-plane disks of single crystal flux grown manganese substituted barium M-type Ba-M and zinc Y

  18. Effect of ferrite powder fineness on the structure and properties of ceramic materials

    SciTech Connect

    Pashchenko, V.P.; Nesterov, A.M.; Litvinova, O.G. [Scientific and Production Association, Donetsk (Russian Federation)] [and others

    1995-03-01

    Comprehensive study of the structure and properties of ferrite materials prepared from powders with different specific surface (0.4 M{sup 2}/g < S{sub sp} < 1.2 m{sub 2/g}) shows that the optimum specific surface of manganese-zinc ferrite powders is about 0.6 m{sup 2}1/g. With an increase in the specific surface of nickel-zinc and barium ferrite powders the porous crystalline structure of sintered specimens and most of the main electromagnetic properties of ferrite articles are improved.

  19. Zinc ferrite nanoparticles activate IL-1b, NFKB1, CCL21 and NOS2 signaling to induce mitochondrial dependent intrinsic apoptotic pathway in WISH cells

    SciTech Connect

    Saquib, Quaiser; Al-Khedhairy, Abdulaziz A.; Ahmad, Javed; Siddiqui, Maqsood A.; Dwivedi, Sourabh; Khan, Shams T. [Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Chair for DNA Research, Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Musarrat, Javed, E-mail: musarratj1@yahoo.com [Chair for DNA Research, Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, U.P. (India)

    2013-12-01

    The present study has demonstrated the translocation of zinc ferrite nanoparticles (ZnFe{sub 2}O{sub 4}-NPs) into the cytoplasm of human amnion epithelial (WISH) cells, and the ensuing cytotoxicity and genetic damage. The results suggested that in situ NPs induced oxidative stress, alterations in cellular membrane and DNA strand breaks. The [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) and neutral red uptake (NRU) cytotoxicity assays indicated 64.48 ± 1.6% and 50.73 ± 2.1% reduction in cell viability with 100 ?g/ml of ZnFe{sub 2}O{sub 4}-NPs exposure. The treated WISH cells exhibited 1.2-fold higher ROS level with 0.9-fold decline in membrane potential (??m) and 7.4-fold higher DNA damage after 48 h of ZnFe{sub 2}O{sub 4}-NPs treatment. Real-time PCR (qPCR) analysis of p53, CASP 3 (caspase-3), and bax genes revealed 5.3, 1.6, and 14.9-fold upregulation, and 0.18-fold down regulation of bcl 2 gene vis-à-vis untreated control. RT{sup 2} Profiler™ PCR array data elucidated differential up-regulation of mRNA transcripts of IL-1b, NFKB1, NOS2 and CCL21 genes in the range of 1.5 to 3.7-folds. The flow cytometry based cell cycle analysis suggested the transfer of 15.2 ± 2.1% (p < 0.01) population of ZnFe{sub 2}O{sub 4}-NPs (100 ?g/ml) treated cells into apoptotic phase through intrinsic pathway. Over all, the data revealed the potential of ZnFe{sub 2}O{sub 4}-NPs to induce cellular and genetic toxicity in cells of placental origin. Thus, the significant ROS production, reduction in ??m, DNA damage, and activation of genes linked to inflammation, oxidative stress, proliferation, DNA damage and repair could serve as the predictive toxicity and stress markers for ecotoxicological assessment of ZnFe{sub 2}O{sub 4}-NPs induced cellular and genetic damage. - Highlights: • First report on the molecular toxicity of ZnFe{sub 2}O{sub 4}-NPs in cells of placental origin • WISH cells treated with ZnFe{sub 2}O{sub 4}-NPs exhibited cytoplasmic localization of NPs. • ZnFe{sub 2}O{sub 4}-NPs induce DNA damage and mitochondrial dysfunction in WISH cells. • ZnFe{sub 2}O{sub 4}-NPs activate inflammatory and oxidative stress signaling in WISH cells. • Elevation of p53, CASP 3, bax and bcl 2 genes affirms intrinsic apoptotic pathway.

  20. 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)

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

    2013-12-01

    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.

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

    SciTech Connect

    Hepworth, M.T.

    1993-10-01

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

  2. Evaluation of the resistance of DNA immobilized on ferrimagnetic particles of cobalt ferrite nanopowder against nuclease cleavage.

    PubMed

    Pershina, A G; Sazonov, A E; Ogorodova, L M

    2010-07-01

    DNA was immobilized on ferrimagnetic particles of cobalt ferrite nanopowder (CoFe(2)O(4)) and its resistance to endonuclease (DNase I) hydrolysis was studied. Immobilization on cobalt ferrite nanoparticles prevented enzymatic cleavage of DNA. This process was not associated with enzyme inactivation under the effect of nanosize cobalt ferrite and was presumably determined by lesser availability of the DNA molecule as a result of its interaction with nanoparticles. PMID:21113461

  3. COLORIMETRIC DETERMINATION OF MANGANESE

    E-print Network

    Bertsch George F.

    1 COLORIMETRIC DETERMINATION OF MANGANESE (Chemistry 51 Version) The objective of this experiment is to determine the percentage of manganese in a steel sample, using colorimetric methods of analysis. PRINCIPLES This analysis is accomplished by dissolving the steel sample, converting all of the manganese to the intensely

  4. Chronic manganese intoxication

    SciTech Connect

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

    1989-10-01

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

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

    PubMed

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

    2011-01-01

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

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

    PubMed Central

    2011-01-01

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

  7. Nanoparticles

    NASA Astrophysics Data System (ADS)

    Vaez-Zadeh, Mehdi; Mohammadi, Ali

    2014-07-01

    MnFe2O4 nanoparticles of various particle sizes were prepared by co-precipitation, in which different hydroxide concentrations were employed to control particle growth. X-ray diffraction and scanning electron microscopy were used to investigate the nanoparticle structure and morphology (shape and size). The particle size increased with increasing hydroxide concentration. The magnetization and coercivity field were measured by vibrating sample magnetometry. Changes in magnetic behavior were observed in the magnetic hysteresis loop curves of nanoparticles with increasing hydroxide concentration. In the absence of hydroxide, nanoparticles exhibited paramagnetic behavior. Increasing the hydroxide concentration caused a gradual conversion to ferrimagnetic behavior. An increased Néel temperature was observed with increasing hydroxide concentration, and the saturation magnetization exhibited a sharp decrease. Nonuniform hysteresis was observed in the magnetization curve for the sample prepared from hydroxide and ammonium.

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

    NASA Astrophysics Data System (ADS)

    Gabal, M. A.

    2009-10-01

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

  9. Controlling transport and chemical functionality of magnetic nanoparticles.

    PubMed

    Latham, Andrew H; Williams, Mary Elizabeth

    2008-03-01

    A wide range of metal, magnetic, semiconductor, and polymer nanoparticles with tunable sizes and properties can be synthesized by wet-chemical techniques. Magnetic nanoparticles are particularly attractive because their inherent superparamagnetic properties make them desirable for medical imaging, magnetic field assisted transport, and separations and analyses. With such applications on the horizon, synthetic routes for quickly and reliably rendering magnetic nanoparticle surfaces chemically functional have become an increasingly important focus. This Account describes common synthetic routes for making and functionalizing magnetic nanoparticles and discusses initial applications in magnetic field induced separations. The most widely studied magnetic nanoparticles are iron oxide (Fe2O3 and Fe3O4), cobalt ferrite (CoFe 2O4), iron platinum (FePt), and manganese ferrite (MnFe 2O4), although others have been investigated. Magnetic nanoparticles are typically prepared under either high-temperature organic phase or aqueous conditions, producing particles with surfaces that are stabilized by attached surfactants or associated ions. Although it requires more specialized glassware, high-temperature routes are generally preferred when a high degree of stability and low particle size dispersity is desired. Particles can be further modified with a secondary metal or polymer to create core-shell structures. The outer shells function as protective layers for the inner metal cores and alter the surface chemistry to enable postsynthetic modification of the surfactant chemistry. Efforts by our group as well as others have centered on pathways to yield nanoparticles with surfaces that are both easily functionalized and tunable in terms of the number and variety of attached species. Ligand place-exchange reactions have been shown quite successful for exchanging silanes, acids, thiols, and dopamine ligands onto the surfaces of some magnetic particles. Poly(ethylene oxide)-modified phospholipids can be inserted into nonpolar surface monolayers of as-prepared nanoparticles as a method for modifying the surface chemistry that induces water solubility. In general, reactive termini can subsequently be used to append a range of chemical groups. For example, surfactants with trifluoroethylester or azide termini have been used to attach a range of amine- or alkyne-containing species, respectively. Chemically functionalized magnetic nanoparticles are promising as advanced materials for analytical separations and analysis. Magnetic field flow fractionation leverages the size-dependent magnetic moments to purify and separate the components of a complex mixture of particles. Similarly, magnetic field gradients are useful for manipulating transport and separation in simple microfluidic devices. By either approach, magnet-induced transport of the particles is a simple method in which an attached reagent, catalyst, or bioanalytical tag can be moved between flow streams within a lab on a chip device. PMID:18251514

  10. Synthesis and characterization of hard magnetic composites—Hollow microsphere\\/titania\\/barium ferrite

    Microsoft Academic Search

    Guohong Mu; Xifeng Pan; Na Chen; Chihuan He; Mingyuan Gu

    2008-01-01

    Hard magnetic composites—hollow microsphere (core)\\/titania (intermediate layer)\\/barium ferrite (magnetic shell) (M\\/T\\/B) were prepared by wet-chemical method. Barium ferrite nanoparticles were directly coated on the rutile titania-coated hollow microsphere forming light hard magnetic composites using sol–gel technique. The prepared composites were characterized with FESEM, EDS, XRD and vibrating sample magnetometry. The composites are composed of barium ferrite, hematite, titania and mullite.

  11. Nanostructured bismuth ferrites synthesized by solvothermal process

    Microsoft Academic Search

    A. Chaudhuri; S. Mitra; M. Mandal; K. Mandal

    2010-01-01

    Well-crystallized bismuth ferrite nanoparticles were synthesized using the solvothermal method without the help of any mineralizer. The shape of the particles was changed by changing the synthesis temperature during solvothermal process. The as-prepared samples were characterized by an X-ray powder diffractometer (XRD), scanning electron microscope (SEM), thermal analyzer and vibrating sample magnetometer (VSM). It was observed that the change in

  12. Magnetic properties of barium ferrite nanoparticles: Quantitative test of the Stoner-Wohlfarth theory for uniaxial single-domain magnetic particles

    NASA Astrophysics Data System (ADS)

    Duan, Hong-yan; Wang, Jun; Li, Le; Aguilar, Victor; Zhao, Guo-meng

    2013-11-01

    We have successfully synthesized single-domain barium ferrite particles with uniaxial anisotropy. We have coated them with amorphous silica to reduce interparticle interactions so that the assembly of these particles behaves like a noninteracting randomly oriented uniaxial single-domain particle system, a prototype for the Stoner-Wohlfarth model. From the magnetic hysteresis loops of the particle system in a wide temperature range (10-700 K), we simultaneously determine the magnetic anisotropic field HK, the reduced remanence Mr/Ms, and the coercive field HC in the whole temperature range below the Curie temperature. These complete sets of data allow us to quantitatively test the Stoner-Wohlfarth theory and the agreement between experiment and theory is good.

  13. Bulk Synthesis of Monodisperse Ferrite Nanoparticles at Water-Organic Interfaces under Conventional and Microwave Hydrothermal Treatment and Their Surface Functionalization

    EPA Science Inventory

    Synthesis of monodisperse MFe2O4 (M=, Ni, Co, Mn) and ¿-Fe2O3 nanoparticles at a water-toluene interface under conventional as well as microwave hydrothermal conditions using readily available nitrate or chloride salts and oleic acid as the dispersing agent is described. The ens...

  14. Manganese laser using manganese chloride as lasant

    NASA Technical Reports Server (NTRS)

    Chen, C. J.

    1974-01-01

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

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

    Microsoft Academic Search

    V. Pillai; D. O. Shah

    1996-01-01

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

  16. Magnetic and Reflection Loss Characteristics of Substituted Barium Ferrite\\/Functionalized Multiwalled Carbon Nanotube

    Microsoft Academic Search

    Ali Ghasemi; Sirus Javadpour; Xiaoxi Liu; Akimitsu Morisako

    2011-01-01

    Magnetic multiwalled carbon nanotube (MWCNTs) nanocomposites have been created by the assembly of Mg-Ni-Ti substituted barium ferrite nanoparticles onto surface of MWCNTs. X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to demonstrate the successful attachment of ferrite nanoparticles to MWCNTs. Vibrating sample magnetometer (VSM) confirms the relatively strong dependence of saturation of magnetization and coercivity with the volume

  17. Manganese 2 -Complexes as Auxiliaries

    E-print Network

    Lepore, Salvatore D.

    Manganese 2 -Complexes as Auxiliaries for Stereoselective Aldol Synthesis of Allenyl Carbinols manganese auxiliary was linked via an 2 -bond to alkynyl esters and ketones using a mild complexation reaction with methylcyclopentadienyl manganese tricarbonyl. This complex readily underwent aldol reactions

  18. Recent Ferrite Magnet Developments

    Microsoft Academic Search

    A. Cochardt

    1966-01-01

    Currently used ferrite magnets (also called ceramic magnets) are modifications of the magnetoplumbites MO·6 Fe2O3 where M stands for Ba or Sr—with additions of other compounds, off-stoichiometric ratios, flexible binders, etc. The first commercial magnetoplumbite magnets were of the barium ferrite type, but the newer ones are modified strontium ferrites which are about 30% higher in coercive force at the

  19. nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  20. BIOLOGICAL EFFECTS OF MANGANESE

    EPA Science Inventory

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

  1. Comminuting irradiated ferritic steel

    DOEpatents

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

    1985-01-01

    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.

  2. Monodisperse cobalt ferrite nanomagnets with uniform silica coatings.

    PubMed

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

    2010-11-16

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

  3. XXIst Century Ferrites

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    Ferrites have always been a subject of great interest from point of view of magnetic application, since the fist compass to present date. In contrast, the scientific interest for iron based magnetic oxides decreased after Ørsted discovery as they where replaced by coil as magnetizing sources. Neel discovery of ferrimagnetism boosted again interest and leads to strong developments during two decades before being of less interest. Recently, the evolution of power electronics toward higher frequency, the downsizing of ceramics microstucture to nanometer scale, the increasing price of rare-earth elements and the development of magnetocaloric materials put light again on ferrites. A review on three ferrite families is given herein: harder nanostructured Ba2+Fe12O19 magnet processed by spark plasma sintering, magnetocaloric effect associated to the spin transition reorientation of W-ferrite and low temperature spark plasma sintered Ni-Zn-Cu ferrites for high frequency power applications.

  4. Bismuth ferrite clusters induced hydrogel formation in human serum albumin.

    PubMed

    Thakur, Garima; Kovur, Prashanthi; Leblanc, Roger M; Thundat, Thomas

    2012-05-01

    Amyloid-fibril formation in human serum albumin (HSA) led to hydrogel formation in the presence of clusters of bismuth ferrite (BiFeO(3) or BFO) nanoparticles (NPs). Factors responsible for hydrogel formation were size and phase of NPs. PMID:22441202

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

    SciTech Connect

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

    2008-12-01

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

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

    Microsoft Academic Search

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

    2002-01-01

    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

  7. Magnetic and magnetostrictive properties of manganese substituted cobalt ferrite

    Microsoft Academic Search

    S. D. Bhame; P. A. Joy

    2007-01-01

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

  8. nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  9. Nanowires of NiCo\\/barium ferrite magnetic composite by electrodeposition

    Microsoft Academic Search

    P. Cojocaru; L. Magagnin; E. Gomez; E. Vallés

    2011-01-01

    Electrodeposition has been demonstrated to be useful in preparing well defined composite nanowires and as a way to modify their magnetic properties. A sulphamate bath containing barium ferrite nanoparticles has been used to test nanoparticle incorporation during an alloy (NiCo) electrodeposition process. The nanoparticles enter the membrane pores during the electrodeposition, being uniformly distributed into them.Home-made alumina membranes prepared in

  10. Impedance calculation for ferrite inserts

    SciTech Connect

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

    2005-01-01

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

  11. Occupational exposure to manganese.

    PubMed Central

    Sari?, M; Marki?evi?, A; Hrusti?, O

    1977-01-01

    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

  12. Recent developments in manganese speciation

    Microsoft Academic Search

    Gareth F. Pearson; Gillian M. Greenway

    2005-01-01

    Manganese is an abundant element in the environment and widely used throughout industry. Although manganese has relatively low toxicity, in chronic overdose or prolonged occupational exposure, it can cause severe disruption to the central nervous system. This article illustrates the requirements for manganese speciation and reviews the analytical methods applied to such studies, including electroanalytical techniques and hybrid systems, such

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

    Microsoft Academic Search

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

    2008-01-01

    Rod-shaped polyaniline (PANI)-barium ferrite nanocomposite was synthesized by in situ polymerization of aniline in the presence of BaFe12O19 nanoparticles with diameters of 60-80 nm. The structure, morphology and properties of the nanocomposite were measured using powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. Different ferrite\\/PANI ratios were selected in order to

  14. Synthesis and characterization of hard magnetic composite photocatalyst—Barium ferrite\\/silica\\/titania

    Microsoft Academic Search

    Seung-woo Lee; Jack Drwiega; David Mazyck; Chang-Yu Wu; Wolfgang M. Sigmund

    2006-01-01

    Hard magnetic composite photocatalytic particles—barium ferrite (magnetic core)\\/silica (intermediate layer)\\/titania (photoactive shell) (B\\/S\\/T) were prepared by wet-chemical methods. Anatase titania nanoparticles were directly coated on the silica-coated barium ferrite forming photoactive titania shell by hydrolysis and condensation of titanium n-butoxide. The prepared hard magnetic composite photocatalyst can be magnetically fluidized and recovered by an applied magnetic field enhancing both the

  15. Magnetic and dielectric properties of barium titanate-coated barium ferrite

    Microsoft Academic Search

    Chao Wang; Xijiang Han; Ping Xu; Xiaohong Wang; Xueai Li; Hongtao Zhao

    2009-01-01

    Flaky barium ferrite with hexagonal molecular structure was successfully prepared by reverse microemulsion method, and was coated with barium titanate through a coordination–precipitation technique. The prepared composite particles were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), vibrating sample magnetometry (VSM) and vector network analyzer. Barium ferrite nanoparticles are proved to be single magnetic

  16. Synthesis, characterization and electrical properties of Nd-doped nano crystalline multiferroic bismuth ferrite

    Microsoft Academic Search

    S. Basu; A. Mukherjee; S. K. M. Houssain; M. Pal

    2011-01-01

    Nd doped bismuth ferrite nanocrystals have been synthesized by the hydrothermal route. XRD, HRTEM, studies were done for the structural characterization of the samples. The a.c. conductivity of different BiFe1?xNdxO3 (x=0, 0.01, 0.03, 0.05, 0.07) nanoparticles have been investigated within a temperature cy dependent 77? T ? 300K. Frequency dependent Conductivity of the nanocrystalline bismuth ferrite samples becomes lower when

  17. Reducing the inversion degree of MnFe2O4 nanoparticles through synthesis to enhance magnetization: evaluation of their (1)H NMR relaxation and heating efficiency.

    PubMed

    Vamvakidis, K; Katsikini, M; Sakellari, D; Paloura, E C; Kalogirou, O; Dendrinou-Samara, C

    2014-09-01

    Manganese ferrite (MnFe2O4) nanoparticles of identical size (9 nm) and with different inversion degrees were synthesized under solvothermal conditions as a candidate theranostic system. In this facile approach, a long-chain amine, oleylamine, was utilized as a reducing and surface-functionalizing agent. The synthesized nanoparticles were shown to have a cubic-spinel structure as characterized by TEM and XRD patterns. Control over their inversion degree was achieved by a simple change of manganese precursor from Mn(acac)2 to Mn(acac)3. The variation in the inversion degree is ascribed to the partial oxidation of Mn(2+) to Mn(3+), as was evidenced by X-ray absorption near edge structure spectroscopy and extended X-ray absorption fine structure spectroscopy at both the Fe and Mn K-edges. The reduction of the inversion degree from 0.42 to 0.22 is close to the corresponding bulk value of 0.20 and led to elevated magnetization (65.7 emu g(-1)), in contrast to the Néel temperature, which was decreased owing to the weaker superexchange interactions between the tetrahedral and octahedral sites within the spinel structure. In order to evaluate the performance of these nanoprobes as a possible bifunctional targeting system, the (1)H NMR relaxation of the samples was tested together with their specific loss power under an alternating magnetic field as a function of concentration. The hydrophobic as prepared MnFe2O4 nanoparticles converted to hydrophilic nanoparticles with cetyltrimethylammonium bromide (CTAB). The MnFe2O4 nanoparticles, well-dispersed in aqueous media, were shown to have r2 relaxivity of up to 345.5 mM(-1) s(-1) and heat release of up to 286 W g(-1), demonstrating their potential use for bioapplications. PMID:25014470

  18. Alcohol-assisted room temperature synthesis of different nanostructured manganese oxides and their pseudocapacitance properties in neutral electrolyte

    NASA Astrophysics Data System (ADS)

    Subramanian, V.; Zhu, Hongwei; Wei, Bingqing

    2008-03-01

    Different nanostructured manganese oxides have been synthesized by a simple precipitation technique using KMnO 4 and different alcohols. The synthesized manganese oxides were extensively studied using TEM, XRD, XPS, surface area measurements and electrochemical studies. TEM observations showed a range of nanostructures from nanowiskers to nanoparticles. This synthesis method promises the tuning of electronic and structural properties of the nanostructured manganese oxides by simply varying the alcohols used in the reactions. MnO 2 shows more whisker-like morphology while the Mn 2O 3 shows particle morphology. The nanostructured manganese oxides showed excellent performance as a pseudocapacitor electrode in a neutral electrolyte.

  19. Ferrite logic reliability study

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Shahdan, Dalila; Ahmad, Sahrim Hj

    2013-05-01

    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.

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

    PubMed Central

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

    2013-01-01

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn3+/Mn4+ ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

  2. Manganese, Metallogenium, and Martian Microfossils

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    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.

  3. Magnetic nanoparticle assembly arrays prepared by hierarchical self-assembly on a patterned surface.

    PubMed

    Wen, Tianlong; Zhang, Dainan; Wen, Qiye; Zhang, Huaiwu; Liao, Yulong; Li, Qiang; Yang, Qinghui; Bai, Feiming; Zhong, Zhiyong

    2015-03-01

    Inverted pyramid hole arrays were fabricated by photolithography and used as templates to direct the growth of colloidal nanoparticle assemblies. Cobalt ferrite nanoparticles deposit in the holes to yield high quality pyramid magnetic nanoparticle assembly arrays by carefully controlling the evaporation of the carrier fluid. Magnetic measurements indicate that the pyramid magnetic nanoparticle assembly arrays preferentially magnetize perpendicular to the substrate. PMID:25712606

  4. Synthesis and Electromagnetic Properties of Polyaniline-barium Ferrite Nanocomposite

    Microsoft Academic Search

    Yuan-Xun Li; Huai-Wu Zhang; Ying-Li Liu; John Q. Xiao

    2007-01-01

    The polyaniline (PANI)-barium ferrite composite with magnetic behavior was synthesized by in situ polymerization of aniline in the presence of BaFe12O19 nanoparticles of 60–80 nm in diameters. The structure, morphology and magnetic properties of samples were characterized by powder X-ray diffraction, Fourier transform infrared, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometer technique. The results of spectroanalysis indicated

  5. Hot coal gas desulfurization with manganese-based sorbents

    SciTech Connect

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

    1995-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Rathod, Sopan M.; Shinde, Ashok B.

    2012-11-01

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

  7. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...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...

  8. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...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...

  9. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...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...

  10. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...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...

  11. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...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...

  12. Low activation ferritic alloys

    DOEpatents

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

    1986-01-01

    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.

  13. Low activation ferritic alloys

    DOEpatents

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

    1985-02-07

    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.

  14. Barium ferrite permanent magnets

    Microsoft Academic Search

    I. Yu. Gershov

    1964-01-01

    1.We have selected and introduced the following optimum conditions for the preparation of isotropic barium ferrite magnets:a)Barium oxide content 15 ± 1%; b) kaolin content 1%; c) roasting of mixture of ferric oxide and barium salt at temperatures of 900–950‡ with five hours holding time; d) pressure during pressing 1.5–2 t\\/cm2; e) sintering of magnets at a temperature of 1160–1260‡

  15. Wear-resistant and electromagnetic absorbing behaviors of oleic acid post-modified ferrite-filled epoxy resin composite coating

    NASA Astrophysics Data System (ADS)

    Wang, Wenjie; Zang, Chongguang; Jiao, Qingjie

    2015-03-01

    The post-modified Mn-Zn ferrite was prepared by grafting oleic acid on the surface of Mn-Zn ferrite to inhibit magnetic nanoparticle aggregation. Fourier Transform Infrared (FT-IR) spectroscopy was used to characterize the particle surfaces. The friction and electromagnetic absorbing properties of a thin coating fabricated by dispersing ferrite into epoxy resin (EP) were investigated. The roughness of the coating and water contact angle were measured using the VEECO and water contact angle meter. Friction tests were conducted using a stainless-steel bearing ball and a Rockwell diamond tip, respectively. The complex permittivity and complex permeability of the composite coating were studied in the low frequency (10 MHz-1.5 GHz). Surface modified ferrites are found to improve magnetic particles dispersion in EP resulting in significant compatibility between inorganic and organic materials. Results also indicate that modified ferrite/EP coatings have a lower roughness average value and higher water contact angle than original ferrite/EP coatings. The enhanced tribological properties of the modified ferrite/EP coatings can be seen from the increased coefficient value. The composite coatings with modified ferrite are observed to exhibit better reflection loss compared with the coatings with original ferrite.

  16. Magnetic and catalytic properties of copper ferrite nanopowders prepared by combustion process.

    PubMed

    Liu, B L; Fu, Y P; Wang, M L

    2009-02-01

    Copper ferrite nano-particles with Fe/Cu ratios varying from 2 to 12 were successfully synthesized by combustion process using copper nitrate, iron nitrate and urea. The resultant powders were investigated by scanning electron microscopy (SEM), vibrating sample magnetometer (VSM). The results revealed that the copper ferrite powders are uniform in the range of 250-300 nm. The copper ferrite with Fe/Cu ratio of 2 possessed a saturation magnetization of 5.47 emu/g, and an intrinsic coercive force of 241.98 Oe, with Fe/Cu ratio of 12 possessed a saturation magnetization of 22.06 emu/g and an intrinsic coercive force of 247.94 Oe. Moreover, these copper ferrite magnetic nano-particles also acted as catalyst for the oxidation of 2,3,6-trimethylphenol to synthesize 2,3,5-trimethylhydrogenquinone and 2,3,5-trimethyl-1,4-benzoquinone for the first time. The conversion of 2,3,6-trimethylphenol in the kinetic behavior of oxidation was investigated in detail. The reaction shows dramatically enhanced by the addition of copper-ferrite nano-particles to the solution. PMID:19441554

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

    Microsoft Academic Search

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

    2001-01-01

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

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

    PubMed

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

    2011-05-24

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

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

    Microsoft Academic Search

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

    2004-01-01

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

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

    PubMed Central

    Birkner, Nancy; Navrotsky, Alexandra

    2014-01-01

    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

  1. The manganese toxicity of cotton.

    PubMed

    Sirkar, S; Amin, J V

    1974-10-01

    Cotton plants (Gossypium hirsutum. Linn. var. Sankar 4) were grown at normal and toxic levels of substrate manganese, and the altered metabolism of manganese toxic plants was studied. The tissues of plants exposed to toxic levels of manganese had higher activities of peroxidase and polyphenol oxidase, and the activities of catalase, ascorbic acid oxidase, glutathione oxidase and cytochrome c oxidase were lowered. In addition, the high manganese tissue had lower contents of ATP and glutathione but higher amounts of ascorbic acid. The respiration of the partially expanded leaves and the growing tips of toxic plants were depressed when compared to that of the normal tissues. The metabolic changes of manganese toxicity of cotton are placed in the following order: accumulation of manganese in the leaf tissue; a rise in respiration; stimulation of polyphenol oxidase; the appearance of initial toxicity symptoms; the evolution of ethylene and stimulation of peroxidase; the presence of severe toxicity symptoms; the depression of terminal oxidases and respiration; abscission of the growing tip and proliferation of the stem tissue. The early stimulation of polyphenol oxidase may be used to detect potential manganese toxicity. PMID:16658924

  2. Distribution of available manganese in Kentucky soils

    Microsoft Academic Search

    J. L. Sims; P. Duangpatra; J. H. Ellis; R. E. Phillips

    1979-01-01

    Laboratory studies were conducted to determine fractions of native soil and applied manganese 54 that contribute to the manganese extracted by DTPA (0.005 M diethylenetriamine pentaacetic acid, 0.005 M CaClâ, 0.1 M triethanolamine, pH 7.3). Since DTPA-extractable manganese is closely related to manganese uptake by plants, such studies should provide information about fractions of soil manganese that contribute most to

  3. Manganese waste water treatment by fungi derived from manganese slag.

    PubMed

    Ou-Yang, Yu-Zhu; Cao, Jian-Bing; Li, Xiao-Ming; Zheng, Wei; Wang, Dong-Bo; Zhang, Yi

    2010-01-01

    The aim of this study was to isolate a mould from the surface of manganese slag which had strong resistance and high adsorption of Mn(2 + ), and to determine the effects of initial Mn(2 + ) concentration, incubation temperature, rotation speed and inoculation amount on adsorption of Mn(2 + ) from manganese waste water solution. The result showed that a mould (A5) which was isolated from manganese slag had the adsorption rate of Mn(2 + ) to 97.5% at the initial pH value 6, inoculation amount 2%, rotation speed 150 r/min, a concentration of Mn(2 + ) 500 mg/L, and a temperature of 28 degrees C cultivated for 50 h. As there is no research on adsorption of Mn(2 + ) from manganese waste water by fungi before, this research showed a theoretical guidance on this field. PMID:20818063

  4. Tellurium content of marine manganese oxides and other manganese oxides

    USGS Publications Warehouse

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

    1963-01-01

    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.

  5. Influence of lanthanum on the optomagnetic properties of zinc ferrite prepared by combustion method

    NASA Astrophysics Data System (ADS)

    Tholkappiyan, R.; Vishista, K.

    2014-09-01

    Pure and lanthanum doped zinc ferrite nanoparticles were synthesized by a combustion method using glycine as fuel. The mechanism of formation of these nanoferrites is discussed briefly. The prepared nanoparticles characterized using powder X-ray diffraction analysis (XRD) revealed the formation of cubic spinel phase with high crystallinity. Average crystallite size, X-ray density and bulk density were found to decrease with an increase in La3+ concentration. The chemical elements and states on the surface of these ferrites were determined using X-ray photoelectron spectroscopy (XPS). The detailed core level spectra of the photoelectron peaks of Zn 2p, Fe 2p, La 3d and O 1s were analyzed. The magnetic behavior of these nanoparticles was studied using a vibrating sample magnetometer (VSM) and corresponding changes in the saturation magnetization (Ms), coercivity (Hc) and remanent magnetization (Mr) were analyzed. The optical behavior of these ferrite nanoparticles was characterized by UV-Diffuse reflectance studies (UV-DRS). From the UV-DRS studies, the optical band gap was found to be in the range of 1.87-1.97 eV. The combustion method significantly produces large amount of products within a short time. Therefore, this method is potentially suitable for manufacturing industries for preparing the magnetic nanoparticles.

  6. 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...

  7. Low Temperature Synthesis of Mn3O4 Nanoparticles Using Starch as Capping Agent

    Microsoft Academic Search

    Jin Mu; Zhenfang Gu; Hua Sun; Qinglian Wei

    2006-01-01

    In this communication, manganese oxide (Mn3O4) nanoparticles were prepared by a facile solution method using starch as capping agent. The nanoparticles were characterized by means of X?ray diffraction (XRD) and AFM. The results showed that the Mn3O4 nanoparticles were single phase, spherical, and uniformly dispersive. The average particle size was evaluated to be approximately 35 nm.

  8. Synthesis of nonstoichiometric M-type barium ferrite nanobelt by spark plasma sintering method

    Microsoft Academic Search

    Wenyu Zhao; Qingjie Zhang; Xinfeng Tang; Haibin Cheng

    2005-01-01

    This study investigated the feasibility of ultrafast crystallization of M-type barium ferrite when the coprecipitation precursors\\u000a in stoichiometric proportions as BaFe12O19, Fe(OH)3 and BaCO3 nanoparticles, had been heated by spark plasma sintering (SPS) process. The results show that SPS method may realize the\\u000a ultrafast crystallization of M-type barium ferrite, absolutely prevent the crystallization of intermediate phase ?-Fe2O3, and significantly decrease

  9. Magnetic nanoparticle assembly arrays prepared by hierarchical self-assembly on a patterned surface

    NASA Astrophysics Data System (ADS)

    Wen, Tianlong; Zhang, Dainan; Wen, Qiye; Zhang, Huaiwu; Liao, Yulong; Li, Qiang; Yang, Qinghui; Bai, Feiming; Zhong, Zhiyong

    2015-03-01

    Inverted pyramid hole arrays were fabricated by photolithography and used as templates to direct the growth of colloidal nanoparticle assemblies. Cobalt ferrite nanoparticles deposit in the holes to yield high quality pyramid magnetic nanoparticle assembly arrays by carefully controlling the evaporation of the carrier fluid. Magnetic measurements indicate that the pyramid magnetic nanoparticle assembly arrays preferentially magnetize perpendicular to the substrate.Inverted pyramid hole arrays were fabricated by photolithography and used as templates to direct the growth of colloidal nanoparticle assemblies. Cobalt ferrite nanoparticles deposit in the holes to yield high quality pyramid magnetic nanoparticle assembly arrays by carefully controlling the evaporation of the carrier fluid. Magnetic measurements indicate that the pyramid magnetic nanoparticle assembly arrays preferentially magnetize perpendicular to the substrate. Electronic supplementary information (ESI) available: Experimental methods and characterization, a TEM image of cobalt ferrite nanoparticles, SEM images of cobalt ferrite nanoparticle crystals on IPHA formed by fast evaporation and slow pulling out from nanoparticle solution by using a dip coater, a SEM image of a partially filled inverted pyramid hole. See DOI: 10.1039/c4nr07489k

  10. Extraction of manganese from electrolytic manganese residue by bioleaching.

    PubMed

    Xin, Baoping; Chen, Bing; Duan, Ning; Zhou, Changbo

    2011-01-01

    Extraction of manganese from electrolytic manganese residues using bioleaching was investigated in this paper. The maximum extraction efficiency of Mn was 93% by sulfur-oxidizing bacteria at 4.0 g/l sulfur after bioleaching of 9days, while the maximum extraction efficiency of Mn was 81% by pyrite-leaching bacteria at 4.0 g/l pyrite. The series bioleaching first by sulfur-oxidizing bacteria and followed by pyrite-leaching bacteria evidently promoted the extraction of manganese, witnessing the maximum extraction efficiency of 98.1%. In the case of sulfur-oxidizing bacteria, the strong dissolution of bio-generated sulfuric acid resulted in extraction of soluble Mn2+, while both the Fe2+ catalyzed reduction of Mn4+ and weak acidic dissolution of Mn2+ accounted for the extraction of manganese with pyrite-leaching bacteria. The chemical simulation of bioleaching process further confirmed that the acid dissolution of Mn2+ and Fe2+ catalyzed reduction of Mn4+ were the bioleaching mechanisms involved for Mn extraction from electrolytic manganese residues. PMID:21050747

  11. 21 CFR 184.1449 - Manganese citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The filtered and washed precipitate...solution to form manganous citrate and then with sodium citrate to complete the reaction....

  12. 21 CFR 184.1449 - Manganese citrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The filtered and washed precipitate...solution to form manganous citrate and then with sodium citrate to complete the reaction....

  13. 21 CFR 184.1449 - Manganese citrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The filtered and washed precipitate...solution to form manganous citrate and then with sodium citrate to complete the reaction....

  14. 21 CFR 184.1449 - Manganese citrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The filtered and washed precipitate...solution to form manganous citrate and then with sodium citrate to complete the reaction....

  15. 21 CFR 184.1449 - Manganese citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The filtered and washed precipitate...solution to form manganous citrate and then with sodium citrate to complete the reaction....

  16. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity...Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in...

  17. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity...Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in...

  18. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity...Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in...

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  20. Biomedical and environmental applications of magnetic nanoparticles

    Microsoft Academic Search

    Dai Lam Tran; Van Hong Le; Hoai Linh Pham; Thi My Nhung Hoang; Thi Quy Nguyen; Thien Tai Luong; Phuong Thu Ha; Xuan Phuc Nguyen

    2010-01-01

    This paper presents an overview of syntheses and applications of magnetic nanoparticles (MNPs) at the Institute of Materials Science, Vietnam Academy of Science and Technology. Three families of oxide MNPs, magnetite, manganite and spinel ferrite materials, were prepared in various ways: coprecipitation, sol–gel and high energy mechanical milling. Basic properties of MNPs were characterized by Vibrating Sample Magnetometer (VSM) and

  1. STRAIN AGING OF AUSTENITIC HADFIELD MANGANESE STEEL

    E-print Network

    Grujicic, Mica

    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

  2. Heteroepitaxial Nucleation and Oriented Growth of Manganese

    E-print Network

    Heteroepitaxial Nucleation and Oriented Growth of Manganese Oxide Islands on Carbonate Minerals and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 Manganese redox cycling study, Mn2+(aq) is reacted with O2(aq) at circumneutral pH to form manganese oxide islands on the (101h4

  3. Original article Studies on differential manganese tolerance

    E-print Network

    Boyer, Edmond

    Original article Studies on differential manganese tolerance of mung bean and rice genotypes germinated and grown in the presence of manganese under controlled environmental conditions. Standard growth tested as markers of manganese toxicity. Measurements as early as 48 hours after the germination did

  4. Original article Intestinal transfer of manganese

    E-print Network

    Paris-Sud XI, Université de

    Original article Intestinal transfer of manganese: resemblance to and competition with calcium Y of calcium, phosphate and the sugars lactose and sorbitol on the intestinal absorption of manganese were / Ca lglucides / phosphates #12;INTRODUCTION The intestinal transport of manganese seems very similar

  5. Manganese depresses rat heart muscle respiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has previously been reported that moderately high dietary manganese (Mn) in combination with marginal magnesium (Mg) resulted in ultrastructural damage to heart mitochondria. Manganese may replace Mg in biological functions, including the role of enzyme cofactor. Manganese may accumulate and subs...

  6. Manganese oxide cathodes for rechargeable batteries

    Microsoft Academic Search

    Dongmin Im

    2002-01-01

    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

  7. Biomarkers of Manganese Intoxication

    PubMed Central

    Zheng, Wei; Fu, Sherleen X.; Dydak, Ulrike; Cowan, Dallas M.

    2010-01-01

    Manganese (Mn), upon absorption, is primarily sequestered in tissue and intracellular compartments. For this reason, blood Mn concentration does not always accurately reflect Mn concentration in the targeted tissue, particularly in the brain. The discrepancy between Mn concentrations in tissue or intracellular components means that blood Mn is a poor biomarker of Mn exposure or toxicity under many conditions and that other biomarkers must be established. For group comparisons of active workers, blood Mn has some utility for distinguishing exposed from unexposed subjects, although the large variability in mean values renders it insensitive for discriminating one individual from the rest of the study population. Mn exposure is known to alter iron (Fe) homeostasis. The Mn/Fe ratio (MIR) in plasma or erythrocytes reflects not only steady-state concentrations of Mn or Fe in tested individuals, but also a biological response (altered Fe homeostasis) to Mn exposure. Recent human studies support the potential value for using MIR to distinguish individuals with Mn exposure. Additionally, magnetic resonance imaging (MRI), in combination with noninvasive assessment of ?-aminobutyric acid (GABA) by magnetic resonance spectroscopy (MRS), provides convincing evidence of Mn exposure, even without clinical symptoms of Mn intoxication. For subjects with long-term, low-dose Mn exposure or for those exposed in the past but not the present, neither blood Mn nor MRI provides a confident distinction for Mn exposure or intoxication. While plasma or erythrocyte MIR is more likely a sensitive measure, the cut-off values for MIR among the general population need to be further tested and established. Considering the large accumulation of Mn in bone, developing an X-ray fluorescence spectroscopy or neutron-based spectroscopy method may create yet another novel non-invasive tool for assessing Mn exposure and toxicity. PMID:20946915

  8. Small high directivity ferrite antennas

    NASA Astrophysics Data System (ADS)

    Wright, T. M. B.

    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.

  9. High power ferrite microwave switch

    NASA Technical Reports Server (NTRS)

    Bardash, I.; Roschak, N. K.

    1975-01-01

    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.

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

    PubMed

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

    2009-07-28

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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

  12. RF cavities with transversely biased ferrite tuning

    SciTech Connect

    Smythe, W.R.; Brophy, T.G.; Carlini, R.D.; Friedrichs, C.C.; Grisham, D.L.; Spalek, G.; Wilkerson, L.C.

    1985-10-01

    Earley et al. suggested that ferrite tuned rf cavities have lower ferrite power dissipation if the ferrite bias field is perpendicular rather than parallel to the rf magnetic field. A 50-84 MHz cavity has been constructed in which ferrite can be biased either way. Low power measurements of six microwave ferrites show that the magnetic Q's of these ferrites under perpendicular bias are much higher than under parallel bias, and that the high Q region extends over a much wider range of rf permeability. TDK Y-5 ferrite was found to have a magnetic Q of 10,800, 4,800, 1,200 and 129 at rf permeabilities of 1.2, 2.4, 3.7 and 4.5, respectively. Measurements of perpendicularly biased ferrite at various power levels were made in a coaxial line cavity. The Q of Y-5 ferrite was found to decrease by less than a factor of 2 as the power density in the ferrite was increased to 1.3 W/cmT. A cavity design for a 6 GeV, high current, rapid cycling synchrotron using transversely biased ferrite tuning is described.

  13. Manganese and chronic hepatic encephalopathy

    Microsoft Academic Search

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

    1995-01-01

    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

  14. Action of manganese on puberty

    E-print Network

    Lee, Bo Yeon

    2007-09-17

    to Mn than adults, we wanted to determine the effects of Mn exposure on puberty-related hormones and the onset of puberty, and discern the site and mechanism of Mn action. We demonstrated that the central administration of manganese chloride (MnCl2...

  15. Manganese Pollution and Violent Crime

    Microsoft Academic Search

    Roger D. Masters

    Evidence of my scientific career and qualification to assess harmful effects of pollution with manganese (or other toxins like lead or hydrofluorosilicic acid) is available in Who's Who in America. In addition to peer reviewed publications on the harmful effects of toxins. I have given papers at the International Society of Neurotoxicology, the American Academy of Environmental Medicine, & other

  16. A ferrite-loaded autoaccelerator

    Microsoft Academic Search

    G. W. Still; J. D. Ivers; J. A. Nation; S. Zhang

    1986-01-01

    An account is presented of the performance of an autoaccelerator in which energy is extracted from the front portion of a relativistic electron beam, via a ferrite-loaded cavity, and stored in an oil-filled transmission line. The extracted energy is returned to augment the energy of the electrons in the latter half of the beam. An increase of up to 33

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

    PubMed

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

    2008-03-12

    Rod-shaped polyaniline (PANI)-barium ferrite nanocomposite was synthesized by in situ polymerization of aniline in the presence of BaFe(12)O(19) nanoparticles with diameters of 60-80 nm. The structure, morphology and properties of the nanocomposite were measured using powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. Different ferrite/PANI ratios were selected in order to study magnetic and conductive properties. The results indicated that there were some interactions between PANI chains and ferrite particles. The saturation magnetization and the coercivity varied with the ferrite content. The conductivity at room temperature decreased from 43.35 to 6.9 × 10(-2) S cm(-1) when the ferrite content changed from 0 to 50 wt%. The composite has excellent electromagnetic parameters which indicates potential application in high performance adsorbing materials in broadband and high frequency ranges. The polymerization mechanism and interactions in the nanocomposites were also studied. PMID:21817707

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

    SciTech Connect

    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

    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.

  19. Cobalt ferrite thin films as anode material for lithium ion batteries

    Microsoft Academic Search

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

    2004-01-01

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

  20. Rare earth influence on the structural and magnetic properties of NiZn ferrites

    Microsoft Academic Search

    S. E Jacobo; S Duhalde; H. R Bertorello

    2004-01-01

    Nanoparticles of Zn0.5Ni0.5R0.02Fe1.98O4 , with R=Y, Gd and Eu, have been prepared by the combustion method. Mössbauer spectroscopy has been used in order to analyse substitution effect on hyperfine parameters. A small increase in the hyperfine field parameters and a strong decrease of the total resonant area have been observed, with respect to the pure Ni-Zn ferrite. Curie temperatures decrease

  1. Low-field DC-magnetization study of Ho 3+-doped Mn–Zn ferrite ferrofluid

    Microsoft Academic Search

    Ramesh V. Upadhyay; Kinnari Parekh; Lybua Belova; K. V. Rao

    2007-01-01

    The physical and magnetic properties of magnetic nanoparticles are crucial for their effectiveness and reliability in biomedical applications. In this article, we report the synthesis of a stable Ho-substituted Mn–Zn ferrite ferrofluid and its physical and magnetic properties. Substitution by rare earth metal plays an important role in determining the magneto-crystalline anisotropy in 4f-3d inter-metallic compounds. Ho3+ substitution not only

  2. High-performance hybrid oxide catalyst of manganese and cobalt for low-pressure methanol synthesis

    NASA Astrophysics Data System (ADS)

    Li, Cheng-Shiuan; Melaet, Gérôme; Ralston, Walter T.; An, Kwangjin; Brooks, Christopher; Ye, Yifan; Liu, Yi-Sheng; Zhu, Junfa; Guo, Jinghua; Alayoglu, Selim; Somorjai, Gabor A.

    2015-03-01

    Carbon dioxide capture and use as a carbon feedstock presents both environmental and industrial benefits. Here we report the discovery of a hybrid oxide catalyst comprising manganese oxide nanoparticles supported on mesoporous spinel cobalt oxide, which catalyses the conversion of carbon dioxide to methanol at high yields. In addition, carbon–carbon bond formation is observed through the production of ethylene. We document the existence of an active interface between cobalt oxide surface layers and manganese oxide nanoparticles by using X-ray absorption spectroscopy and electron energy-loss spectroscopy in the scanning transmission electron microscopy mode. Through control experiments, we find that the catalyst’s chemical nature and architecture are the key factors in enabling the enhanced methanol synthesis and ethylene production. To demonstrate the industrial applicability, the catalyst is also run under high conversion regimes, showing its potential as a substitute for current methanol synthesis technologies.

  3. High-performance hybrid oxide catalyst of manganese and cobalt for low-pressure methanol synthesis.

    PubMed

    Li, Cheng-Shiuan; Melaet, Gérôme; Ralston, Walter T; An, Kwangjin; Brooks, Christopher; Ye, Yifan; Liu, Yi-Sheng; Zhu, Junfa; Guo, Jinghua; Alayoglu, Selim; Somorjai, Gabor A

    2015-01-01

    Carbon dioxide capture and use as a carbon feedstock presents both environmental and industrial benefits. Here we report the discovery of a hybrid oxide catalyst comprising manganese oxide nanoparticles supported on mesoporous spinel cobalt oxide, which catalyses the conversion of carbon dioxide to methanol at high yields. In addition, carbon-carbon bond formation is observed through the production of ethylene. We document the existence of an active interface between cobalt oxide surface layers and manganese oxide nanoparticles by using X-ray absorption spectroscopy and electron energy-loss spectroscopy in the scanning transmission electron microscopy mode. Through control experiments, we find that the catalyst's chemical nature and architecture are the key factors in enabling the enhanced methanol synthesis and ethylene production. To demonstrate the industrial applicability, the catalyst is also run under high conversion regimes, showing its potential as a substitute for current methanol synthesis technologies. PMID:25754475

  4. Manganese partitioning in low carbon manganese steel during annealing

    Microsoft Academic Search

    J. Lis; A. Lis; C. Kolan

    2008-01-01

    For 6Mn16 steel experimental soft annealing at 625 °C for periods from 1 h to 60 h and modeling with Thermo-Calc were performed to estimate the partitioning of alloying elements, in particular Mn, between ferrite, cementite and austenite. Using transmission electron microscopy and X-ray analysis it was established that the increase of Mn concentration in carbides to a level 7%–11.2% caused a local

  5. Chemical and microbiological studies of sulfide?mediated manganese reduction

    Microsoft Academic Search

    David J. Burdige; Kenneth H. Nealson

    1986-01-01

    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

  6. MANGANESE--1997 49.1 By Thomas S. Jones

    E-print Network

    Torgersen, Christian

    MANGANESE--1997 49.1 MANGANESE By Thomas S. Jones Manganese (Mn) is essential to iron and steel,includingitsironmakingcomponent,hasaccounted for most domestic manganese demand, presently in the range of 85% to 90% of the total demand. Among a variety of other uses, manganese is a key component of certain widely used aluminum alloys and is used

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

    SciTech Connect

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

    2011-12-13

    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.

  8. Nickel and manganese transfer from soil to plant in lateritic mining soils from New Caledonia

    NASA Astrophysics Data System (ADS)

    Pouschat, P.; Rose, J.; Alliot, I.; Dominici, C.; Keller, C.; Laffont-Schwob, I.; Olivi, L.; Ambrosi, J.-P.

    2009-04-01

    New Caledonian ferritic soils (more than 50 % of iron) are naturally rich in metals (chromium, nickel, cobalt, and manganese), deficient in major nutrients (nitrogen, phosphorous, and potassium), and unbalanced for the calcium/magnesium ratio. Under these particular ecological conditions, New Caledonia, recognized as a hot-spot of biodiversity, is a natural laboratory to study and understand the adaptation strategies of plants to metalliferous soils, and particularly the tolerance and (hyper)accumulation of metals by plants. Moreover, understanding such mechanisms is essential to develop rehabilitation or phytoremediation techniques for polluted soils, as well as phytomining techniques. Thus, in order to understand the soil - plant relationship and metal mobility along a toposequence in a future nickel mining massif, field experiments were conducted in an isolated ultramafic massif of New Caledonia. Several plant species of two endemic and frequent plant genera were chosen: Tristaniopsis guillainii and T. calobuxus (Myrtaceae), and Phyllanthus serpentinus and P. favieri (Euphorbiaceae), because of their nickel and/or manganese accumulating or hyperaccumulating nature. Leaves, twigs, and roots of all plants were collected along the soil sequence and their associated rhizospheric and bulk soils were sampled. Next, a series of characterization techniques were adapted and then coupled to cryogenics. The combined use of those multiple techniques (cryo-microtomy, cryo-SEM, µXRF, cryo-XAS, and soil characterization) allowed to study co-location and speciation of nickel and manganese in the different plant organs and soils (rhizospheric and bulk). Bioaccumulated nickel and manganese had different distribution patterns. In leaves, Ni accumulated in non photosynthetic tissues (e.g. epidermis) whereas Mn preferentially accumulated in mesophyll whatever the plant species. Nevertheless, in spite of a different speciation in soils, nickel and manganese were both found as similar divalent organometallic complexes in the different plant parts.

  9. Filling Narrow Trenches by Iodine-Catalyzed CVD of Copper and Manganese on Manganese Nitride Barrier/Adhesion Layers

    E-print Network

    Filling Narrow Trenches by Iodine-Catalyzed CVD of Copper and Manganese on Manganese Nitride). Conformally deposited manganese nitride serves as an underlayer that initially chemisorbs iodine. CVD of copper or copper-manganese alloy releases the adsorbed iodine atoms from the surface of the manganese

  10. Development of a monolithic ferrite memory array

    NASA Technical Reports Server (NTRS)

    Heckler, C. H., Jr.; Bhiwandker, N. C.

    1972-01-01

    The results of the development and testing of ferrite monolithic memory arrays are presented. This development required the synthesis of ferrite materials having special magnetic and physical characteristics and the development of special processes; (1) for making flexible sheets (laminae) of the ferrite composition, (2) for embedding conductors in ferrite, and (3) bonding ferrite laminae together to form a monolithic structure. Major problems encountered in each of these areas and their solutions are discussed. Twenty-two full-size arrays were fabricated and fired during the development of these processes. The majority of these arrays were tested for their memory characteristics as well as for their physical characteristics and the results are presented. The arrays produced during this program meet the essential goals and demonstrate the feasibility of fabricating monolithic ferrite memory arrays by the processes developed.

  11. Anechoic chamber having multi-layer electromagnetic wave absorbers of sintered ferrite and ferrite composite membrane

    Microsoft Academic Search

    K. Naito; Tetsuya Mizumoto; Michiharu Takahashi; Sumio Kunieda

    1994-01-01

    The structure of the multi-layer electromagnetic wave absorber composed of sintered ferrite and ferrite composite membrane is proposed to improve radiowave absorbing characteristics. The absorption characteristics of the multi-layer absorber can be largely extended compared with the single sintered ferrite layer. Moreover, it is shown that the site attenuation characteristics satisfy the FCC standard for 3 m and 10 m

  12. Barium ferrite thin-film recording media

    Microsoft Academic Search

    Xiaoyu Sui; Matthias Scherge; Mark H. Kryder; John E. Snyder; Vincent G. Harris; Norman C. Koon

    1996-01-01

    Both longitudinal and perpendicular barium ferrite thin films are being pursued as overcoatless magnetic recording media. In this paper, prior research on thin-film Ba ferrite is reviewed and the most recent results are presented. Self-textured high-coercivity longitudinal Ba ferrite thin films have been achieved using conventional rf diode sputtering. Microstructural studies show that c-axis in-plane oriented grains have a characteristic

  13. Fabrication of Barium Ferrite Thick Films

    Microsoft Academic Search

    Wei Jiang Yeh; Carla Blengeri-Oyarce; Sundeep Pillamari; Jnana Manoj Appikonda; Laura Diaz; Yanko Kranov; David McIlroy

    2008-01-01

    During recent years the need for high quality self-biased barium ferrite (BaFe12O19) thick films had been increasing due to its chemical stability, anisotropy and oriented hexagonal M-type ferrites. Our goal is to fabricate barium ferrite thick films to be incorporated in self-biased microwave devises. Different methods such as sputtering, pulse laser deposition, CVD and modified liquid phase deposition have been

  14. Spectroscopic characterization of manganese minerals.

    PubMed

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

    2014-01-01

    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. PMID:23995604

  15. 40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...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...

  16. 40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

  17. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 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...

  18. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Barium calcium manganese strontium oxide. 721.10011 Section...Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance...substance identified as barium calcium manganese strontium oxide (PMN...

  19. 40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

  20. 40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...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...

  1. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 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...

  2. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...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...

  3. 40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...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...

  4. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...false Cobalt lithium manganese nickel oxide. 721.10201 Section...10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance...as cobalt lithium manganese nickel oxide (PMN P-04-269...Requirements as specified in § 721.63 (a)(1),...

  5. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...false Cobalt lithium manganese nickel oxide. 721.10201 Section...10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance...as cobalt lithium manganese nickel oxide (PMN P-04-269...Requirements as specified in § 721.63 (a)(1),...

  6. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...false Cobalt lithium manganese nickel oxide. 721.10201 Section...10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance...as cobalt lithium manganese nickel oxide (PMN P-04-269...Requirements as specified in § 721.63 (a)(1),...

  7. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Barium calcium manganese strontium oxide. 721.10011...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a...chemical substance identified as barium calcium manganese strontium oxide (PMN...

  8. Iron and manganese in lakes

    Microsoft Academic Search

    William Davison

    1993-01-01

    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

  9. Ferrite Loaded DBD Plasma Device

    NASA Astrophysics Data System (ADS)

    Machida, M.

    2015-02-01

    An atmospheric pressure plasma jet device with dielectric barrier discharge was built using low cost 5C22 thyratron valve and ferrite transformer. The ferrite transformer increases the intensity about four times the primary pulse and lengthens the high voltage pulse, keeping the rise time of the thyratron pulse. Spectrometer measurement shows excited nitrogen molecular emissions of second positive system. The most intense nitrogen molecular line, 357.69 nm, was chosen to monitor the time dependence of the discharge. Synthetic temperature, using 380.49 nm line of N2 emission and SpecAir simulation, shows plasma gas temperature of 300 K. To corroborate this low temperature, the plasma jet is applied to human tongue with no harm or bad physical feeling.

  10. Investigations on Barium Ferrite Magnets

    Microsoft Academic Search

    K. J. Sixtus; K. J. Kronenberg; R. K. Tenzer

    1956-01-01

    Barium ferrite (BaO:6Fe2O3) has been investigated magnetically to test the predictions of fine particle theory in the region of grain sizes larger than the critical one for which no satisfactory theory exists as yet. Grain size and coercive force of polycrystalline magnets (nonoriented and crystal oriented) were closely related to sintering temperatures. A comparison of theoretical and observed temperature dependence

  11. Negative impact of manganese on honeybee foraging.

    PubMed

    Søvik, Eirik; Perry, Clint J; LaMora, Angie; Barron, Andrew B; Ben-Shahar, Yehuda

    2015-03-01

    Anthropogenic accumulation of metals such as manganese is a well-established health risk factor for vertebrates. By contrast, the long-term impact of these contaminants on invertebrates is mostly unknown. Here, we demonstrate that manganese ingestion alters brain biogenic amine levels in honeybees and fruit flies. Furthermore, we show that manganese exposure negatively affects foraging behaviour in the honeybee, an economically important pollinator. Our findings indicate that in addition to its direct impact on human health, the common industrial contaminant manganese might also have indirect environmental and economical impacts via the modulation of neuronal and behavioural functions in economically important insects. PMID:25808001

  12. Gas sensing properties of ZnFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Misra, Susmita; Ram, S.

    2013-06-01

    Gas sensing performance of ZnFe2O4 ferrite nanoparticles towards various organic volatile compounds is investigated. A self-combustion of a citrate-gel precursor at ˜90 °C in ambient air followed by annealing at 400 °C for 2 h has been explored to prepare a single phase spinel ferrite powder containing granular nanoparticles of average 23 nm diameters. A powder compact measures chemiresistive sensitivity of 59, 51, and 67% for organic vapor-analytes methanol, ethanol, and acetone respectively of 200 ppm at 250 °C. Excellent sensitivity of the granular nanoparticles results due to a large surface area to volume ratio effect.

  13. Magnetic nanoparticles coated with polysaccharide polymers for potential biomedical applications

    Microsoft Academic Search

    Cristina Ileana Covaliu; Daniela Berger; Cristian Matei; Lucian Diamandescu; Eugeniu Vasile; Camelia Cristea; Valentin Ionita; Horia Iovu

    This study reports a two-steps route for obtaining magnetic nanoparticles–polysaccharide hybrid materials consisting of Fe3O4, NiFe2O4 and CuFe2O4 nanoparticles synthesis by coprecipitation method in the presence of a soft template followed by coating of ferrite nanoparticles\\u000a of 8–10-nm size range with polysaccharide type polymers—sodium alginate or chitosan. Magnetic oxide nanoparticles and the\\u000a corresponding hybrid materials were characterized by X-ray diffraction

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two-electrode supercapacitors demonstrated high capacitance (260.2 F g-1), energy (9.0 W h kg-1), power (59.7 kW kg-1), and cycle stability (12% drop after 3000 cycles). In addition, the nanocomposites show good strength and excellent mechanical flexibility, and their capacitance shows negligible changes after bending more than 100 times. These findings suggest that opportunities exist to further explore the rich chemistry of cellulose fibers for innovative energy applications.Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two-electrode supercapacitors demonstrated high capacitance (260.2 F g-1), energy (9.0 W h kg-1), power (59.7 kW kg-1), and cycle stability (12% drop after 3000 cycles). In addition, the nanocomposites show good strength and excellent mechanical flexibility, and their capacitance shows negligible changes after bending more than 100 times. These findings suggest that opportunities exist to further explore the rich chemistry of cellulose fibers for innovative energy applications. Electronic supplementary information (ESI) available: Chemical structures of functional groups on cellulose fibers, the surface water wettability of rice paper, CV curves of supercapacitors at different scan rates, galvanostatic charge-discharge curves of supercapacitors at different current densities, TGA profiles of the SWCNT-MnO2-paper composites synthesized at different temperatures, TEM images of MnO2 particles deposited on rice paper at different temperatures, photographs of supercapacitors under different bending test conditions, and a video of bending and folding the SWCNT-MnO2-paper composites. See DOI: 10.1039/c3nr03010e

  15. Noise characterisation of barium ferrite dispersions

    Microsoft Academic Search

    S. M. McCann; P. M. Sollis; P. R. Bissell; T. Onions

    1999-01-01

    Structural changes in barium ferrite dispersions during the milling process have been investigated by using noise measurements of the remanent states (DC modulation noise). Doped barium ferrite particles mixed with solvents, self wetting resins and binders were dispersed using a bead mill. Samples extracted at intervals during the process were coated onto PET film and magnetically oriented before drying. Tapes

  16. Tribological properties of barium ferrite films

    Microsoft Academic Search

    M. Scherge; X. Sui; X. Ma; C. L. Bauer; M. S. Jhon; M. H. Kryder

    1995-01-01

    Acoustic emission and friction coefficients have been measured during start-stop and continuous sliding for pure and doped barium ferrite films, without lubrication, and compared with concomitant surface topography and magnetic properties. Barium ferrite films averaging about 100 nm in thickness, were produced on thermally oxidized Si substrates by sputter deposition and then furnace or rapid thermal annealed in order to

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

    PubMed

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

    2014-08-01

    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

  18. Enhancement of the physical properties of rare-earth-substituted Mn–Zn ferrites prepared by flash method

    Microsoft Academic Search

    M. A. Ahmed; N. Okasha; M. M. El-Sayed

    2007-01-01

    The effect of rare-earth ions on the structural, magnetic and electrical properties of rare-earth-doped manganese–zinc ferrite is reported. The compounds with the formula Mn0.5Zn0.5R0.05Fe1.95O4 where R=Tb, La, Ce and Th, were prepared by the flash combustion technique. The prepared samples reveal that by introducing a relatively small amount of R(NO3)3 or R(Cl3) instead of Fe2O3, an important modification of both

  19. Manganese nodules: thorium-230: protactinium-231 ratios.

    PubMed

    Sackett, W M

    1966-11-01

    The Th(230): Pa(231) activity ratio in 7 of 11 manganese nodules is less than 10.8, the theoretical production ratio of activities in the ocean. This finding indicates difierential accumulation of these nuclides in authigenic deposits of manganese-iron oxide. PMID:17778807

  20. Drinking Water Problems: Iron and Manganese

    E-print Network

    Dozier, Monty; McFarland, Mark L.

    2004-02-20

    Iron and manganese can give water an unpleasant taste, odor and color. In this publication you'll learn how to know whether your water contains iron or manganese and how to eliminate these contaminants with various treatment methods such as aeration...

  1. Manganese and Oxidative Damage in Cucumber

    Microsoft Academic Search

    Rajeev Gopal

    2008-01-01

    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

  2. Magnetic and ultrasonic studies on stable cobalt ferrite magnetic nanofluid.

    PubMed

    Nabeel Rashin, M; Hemalatha, J

    2014-03-01

    Stable cobalt ferrite nanofluids of various concentrations have been prepared through co-precipitation method. Structural and morphological studies of nanoparticles are made with the help of X-ray diffraction technique and Transmission Electron Microscope respectively and it is found that the particles exhibit face centered cubic structure with an average size of 14 nm. The magnetic properties of the nanofluids have been analyzed at room temperature which revealed ferromagnetic behavior and also the very low value of coupling constant which ensures the negligible interparticle interaction in the absence of magnetic field. Ultrasonic investigations have been made for the nanofluids at different temperatures and magnetic fields. The temperature effects are explained with the help of open and close-packed water structure. The inter particle interactions of surface modified CoFe2O4 particles and the cluster formation at higher concentrations are realized through the variations in ultrasonic parameters. PMID:24188514

  3. Preparation of ferrite-coated MFM cantilevers

    NASA Astrophysics Data System (ADS)

    Koblischka, M. R.; Kirsch, M.; Wei, J.; Sulzbach, T.; Hartmann, U.

    2007-09-01

    Ferrite-coated magnetic force microscopy (MFM) cantilevers were prepared for the use with a high-frequency MFM (HF-MFM) setup. The ferrite coatings were fabricated by means of radio frequency (RF) magnetron sputtering directly on the Si surface. Two types of ferrites were employed in this study: NiZnFe 2O 4 spinel and Co 2Z-type hexaferrite (Ba 3Co 2Fe 24O 41, BCFO). The typical thickness of the coatings was 50 nm. For comparison, ferrite samples on (1 0 0) and (1 1 1)-oriented Si substrates (analogous to the surfaces of the cantilevers) were prepared. Successful HF-MFM imaging was performed with both types of cantilevers using harddisk writer poles as samples. The HF-MFM images obtained by ferrite-coated cantilevers evidently reveal more details of the magnetic field distribution of the writer poles up to the GHz range than conventional CoCr-coated MFM cantilevers.

  4. Structural, electrical and magnetic characteristics of nickel substituted cobalt ferrite nano particles, synthesized by self combustion method

    NASA Astrophysics Data System (ADS)

    Sontu, Uday Bhasker; Yelasani, Vijayakumar; Musugu, Venkata Ramana Reddy

    2015-01-01

    Nickel-substituted cobalt ferrite nano-particles are synthesized using a self-combustion method. Aqueous metal nitrates and citric acid form the precursors. No external oxidizing agents are used to change the pH of the precursors; this resulted in a more environment friendly synthesis. Structural, magnetic and electrical characteristics of the nano ferrites are verified using X-ray diffractometer (XRD), VSM and impedance analyzer respectively. Phase formation, particle size, lattice parameter, X-ray density, saturation magnetization, coercivity, dielectric constant and electrical activation energy as function of nickel substitution in cobalt ferrite are studied. It is shown here that the magnetic and electrical properties can be tuned by varying the nickel concentration.

  5. Structural Features of Manganese Precipitating Bacteria

    NASA Astrophysics Data System (ADS)

    Nealson, Kenneth H.; Tebo, Bradley

    1980-06-01

    Studies of biological communities of the past (and their associated activities) are usually dependent upon preservation of fossil material. With bacteria this rarely occurs because of the absence of sufficient fossilizable cellular material. However, some bacteria deposit metabolic products that can, conditions allowing, be preserved indefinitely. In particular, manganese and iron depositing bacteria have the capacity to form preservable microfossils. In order to better understand these microfossils of the past, we have examined present day morphologies of manganese oxidizing bacteria. These bacteria are highly pleomorphic, depending on the growth medium, the age of the culture, and the extent of manganese oxidation. Transmission electron microscopy indicates that manganese may be deposited either intra-or extra-cellularly. The prognosis of the use of morphological information for the interpretation of ancient and modern manganese deposits is discussed.

  6. Manganese regulates expression of manganese peroxide by Phanerochaete chrysosporium

    SciTech Connect

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

    1990-06-01

    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.

  7. Dinuclear manganese centers in the manganese-lead-tellurate glasses.

    PubMed

    Rada, S; Dehelean, A; Culea, M; Culea, E

    2011-07-01

    FTIR, UV-VIS and EPR spectra of manganese doped lead-tellurate glasses with composition xMnO·(100-x)[4TeO2·PbO2] where x=0, 1, 5, 10, 20, 30, 40mol% have been studied. The FTIR spectra show the formation of the Mn-O-Pb and Mn-O-Te bridging bonds by increasing of MnO concentration. The UV-VIS spectra show the Mn(+3) species exhibit pronounced absorption, which masks the Mn(+2) spin-forbidden absorption bands when Mn(+2) ions are in high concentrations in these glasses. The EPR spectra exhibit resonance signals characteristic of Mn(+2) ions. The resonance signal located at g?2 is due to Mn(+2) ions in an environment close to octahedral symmetry, whereas the resonance at g?4.3 and 3.3 are attributed to the rhombic surroundings of the Mn(+2) ions. The increase in the MnO content gives rise to absorption at g?2.4 and the paramagnetic ions are involved in dinuclear manganese centers. PMID:21498108

  8. Manganese borohydride; synthesis and characterization.

    PubMed

    Richter, Bo; Ravnsbæk, Dorthe B; Tumanov, Nikolay; Filinchuk, Yaroslav; Jensen, Torben R

    2015-02-17

    Solvent-based synthesis and characterization of ?-Mn(BH4)2 and a new nanoporous polymorph of manganese borohydride, ?-Mn(BH4)2, via a new solvate precursor, Mn(BH4)2·1/2S(CH3)2, is presented. Manganese chloride is reacted with lithium borohydride in a toluene/dimethylsulfide mixture at room temperature, which yields halide and solvent-free manganese borohydride after extraction with dimethylsulfide (DMS) and subsequent removal of residual solvent. This work constitutes the first example of establishing a successful, reproducible solvent-based synthesis route for a pure, crystalline, stable transition metal borohydride. The new polymorph, ?-Mn(BH4)2, is shown to be the manganese counterpart of the zeolite-like compound, ?-Mg(BH4)2 (cubic, a = 16.209(1) Å, space group Id3[combining macron]a). It is verified that large pores (diameter > 6.0 Å) exist in this structure. The solvate, Mn(BH4)2·1/2S(CH3)2, is subsequently shown to be the analogue of Mg(BH4)2·1/2S(CH3)2. As the structural analogies between Mg(BH4)2 and Mn(BH4)2 became evident a new polymorph of Mg(BH4)2 was identified and termed ?-Mg(BH4)2. ?-Mg(BH4)2 is the structural counterpart of ?-Mn(BH4)2. All synthesis products are characterized employing synchrotron radiation-powder X-ray diffraction, infrared spectroscopy and thermogravimetric analysis in combination with mass spectroscopy. Thermal analysis reveals the decomposition of Mn(BH4)2 to occur at 160 °C, accompanied by a mass loss of 14.8 wt%. A small quantity of the desorbed gaseous species is identified as diborane (?m(Mn(BH4)2) = 9.5 wt% H2), while the remaining majority is found to be hydrogen. PMID:25611294

  9. Static magnetization and microwave loss in shock-modified ferrites

    SciTech Connect

    Venturini, E.L.; Graham, R.A.; Morosin, B.

    1987-01-01

    High-pressure shock loading of cubic nickel ferrite and hexagonal barium ferrite powders results in substantial residual strain, producing changes in the magnetic anisotropy through magnetostrictive coupling. Both the static magnetization and the absorption of microwaves are strongly altered in nickel ferrite, with somewhat smaller changes in barium ferrite.

  10. Application of Ferrite to Electromagnetic Wave Absorber and its Characteristics

    Microsoft Academic Search

    YOSHIYUKI NAITO; KUNIHIRO SUETAKE

    1971-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  12. Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature.

    PubMed

    Sedlacik, Michal; Pavlinek, Vladimir; Peer, Petra; Filip, Petr

    2014-05-14

    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

  13. Synthesis of copper ferrite from thermolysis of copper ferrimalonate precursor (invited)

    NASA Astrophysics Data System (ADS)

    Singh, Jashanpreet; Kaur, Harpreet; Kaur, Manpreet; Randhawa, B. S.

    2010-05-01

    The thermolysis of copper ferrimalonate Cu3[Fe(CH2C2O4)3]2?9H2O has been investigated up to 1073 K in flowing air atmosphere employing various physico-chemical techniques, i.e., simultaneous TG-DTG-DSC, XRD, Mössbauer, IR, and TEM. The precursor undergoes dehydration and decomposition simultaneously to yield copper malonate and iron(II) malonate intermediates at 433 K. At higher temperature (548 K) these intermediate species decompose to CuO and ?-Fe2O3, respectively. Finally, copper ferrite, CuFe2O4, has been obtained as a result of solid state reaction between ?-Fe2O3 and CuO at a temperature (623 K) much lower than that for conventional ceramic method. The TEM analysis of the final thermolysis product reveals the formation of monodisperse copper ferrite nanoparticles with an average particle size of 33 nm. Magnetic studies show that these nanoparticles exhibit saturation magnetization of 2783 G and Curie temperature of 709 K. Lower magnitude of these parameters as compared with the bulk values may be attributed to the ultrafine grain size of the ferrite particles.

  14. MANGANESE--1999 49.1 By Thomas S. Jones

    E-print Network

    Torgersen, Christian

    MANGANESE--1999 49.1 MANGANESE By Thomas S. Jones Domestic survey data and tables were prepared. Wallace, international data coordinators. Manganese (Mn) is essential to iron and steel production component, has accounted for most domestic manganese demand, presently in the range of 85% to 90

  15. MANGANESE--2000 50.1 By Thomas S. Jones

    E-print Network

    Torgersen, Christian

    MANGANESE--2000 50.1 MANGANESE By Thomas S. Jones Domestic survey data and tables were prepared. Wallace, international data coordinator. Manganese (Mn) is essential to iron and steel production component, has accounted for most domestic manganese demand, presently in the range of 85% to 90

  16. MANGANESE--2002 49.1 By Lisa A. Corathers

    E-print Network

    Torgersen, Christian

    MANGANESE--2002 49.1 MANGANESE By Lisa A. Corathers Domestic survey data and tables were prepared Logistics Agency issued on October 1, 2002, was the same with respect to manganese as in the revised fiscal year 2002 AMP issued on October 1, 2001, with the exception of the manganese ferrogroup. The AMP

  17. MANGANESE--2003 48.1 By Lisa A. Corathers

    E-print Network

    Torgersen, Christian

    MANGANESE--2003 48.1 MANGANESE By Lisa A. Corathers Domestic survey data and tables were prepared on December 23, 2002, was the same with respect to manganese as in the revised fiscal year 2002 AMP issued September 30, 2003. Under this AMP, the maximum disposal authority for manganese materials was 226

  18. MANGANESE--2001 49.1 By Lisa A. Corathers

    E-print Network

    Torgersen, Christian

    MANGANESE--2001 49.1 MANGANESE By Lisa A. Corathers Domestic survey data and tables were prepared. Wallace, international data coordinator. Manganese is essential to iron and steel production by virtue component, has accounted for most domestic manganese demand, presently in the range of 85% to 90

  19. MANGANESE--1998 49.1 By Thomas S. Jones

    E-print Network

    Torgersen, Christian

    MANGANESE--1998 49.1 MANGANESE By Thomas S. Jones Domestic survey data and tables were prepared. Wallace, international data coordinator. Manganese is essential to iron and steel production by virtue component, has accounted for most domestic manganese demand, presently in the range of 85% to 90

  20. Manganese oxidation by Leptothrix discophora.

    PubMed Central

    Boogerd, F C; de Vrind, J P

    1987-01-01

    Cells of Leptothrix discophora SS1 released Mn2+-oxidizing factors into the medium during growth in batch culture. Manganese was optimally oxidized when the medium was buffered with HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) at pH 7.5. Manganese-oxidizing activity in the culture medium in which this strain had been grown previously was sensitive to heat, phosphate, Tris, NaN3, HgCl2 NaCl, sodium dodecyl sulfate, and pronase; 0.5 mol of O2 was consumed per mol of MnO2 formed. During Mn2+ oxidation, protons were liberated. With sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two protein-containing bands were detected in the spent culture medium. One band had an apparent molecular weight of 110,000 and was predominant in Mn2+-oxidizing activity. The second product (Mr 85,000) was only detected in some cases and probably represents a proteolytic breakdown moiety of the 110,000-Mr protein. The Mn2+-oxidizing factors were associated with the MnO2 aggregates that had been formed in spent culture medium. After solubilization of this MnO2 with ascorbate, Mn2+-oxidizing activity could be recovered. Images PMID:3804969

  1. Diclofenac and 2?anilinophenylacetate degradation by combined activity of biogenic manganese oxides and silver

    PubMed Central

    Meerburg, Francis; Hennebel, Tom; Vanhaecke, Lynn; Verstraete, Willy; Boon, Nico

    2012-01-01

    Summary The occurrence of a range of recalcitrant organic micropollutants in our aquatic environment has led to the development of various tertiary wastewater treatment methods. In this study, biogenic manganese oxides (Bio?MnOx), biogenic silver nanoparticles (Bio?Ag0) and ionic silver were used for the oxidative removal of the frequently encountered drug diclofenac and its dechlorinated form, 2?anilinophenylacetate (APA). Diclofenac was rapidly degraded during ongoing manganese oxidation by Pseudomonas putida MnB6. Furthermore, whereas preoxidized Bio?MnOx, Bio?Ag0 and Ag+ separately did not show any removal capacity for diclofenac, an enhanced removal occurred when Bio?MnOx and silver species were combined. Similar results were obtained for APA. Finally, a slow removal of diclofenac but more rapid APA degradation was observed when silver was added to manganese?free P.?putida biomass. Combining these results, three mechanisms of diclofenac and APA removal could be distinguished: (i) a co?metabolic removal during active Mn2+ oxidation by P.?putida; (ii) a synergistic interaction between preoxidized Bio?MnOx and silver species; and (iii) a (bio)chemical process by biomass enriched with silver catalysts. This paper demonstrates the use of P.?putida for water treatment purposes and is the first report of the application of silver combined with biogenic manganese for the removal of organic water contaminants. PMID:22221449

  2. Synthesis of nanostructured manganese oxides based materials and application for supercapacitor

    NASA Astrophysics Data System (ADS)

    Dung Dang, Trung; Le, Thi Thu Hang; Bich Thuy Hoang, Thi; Mai, Thanh Tung

    2015-01-01

    Manganese oxides are important materials with a variety of applications in different fields such as chemical sensing devices, magnetic devices, field-emission devices, catalysis, ion-sieves, rechargeable batteries, hydrogen storage media and microelectronics. To open up new applications of manganese oxides, novel morphologies or nanostructures are required to be developed. Via sol—gel and anodic electrodeposition methods, M (Co, Fe) doped manganese oxides were prepared. On the other hand, nanostructured (nanoparticles, nanorods and hollow nanotubes) manganese oxides were synthesized via a process including a chemical reaction with carbon nanotubes (CNTs) templates followed by heat treatment. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV) and impedance spectroscopy (EIS) were used for characterization of the prepared materials. The influence of chemical reaction conditions, heat treatment and template present on the morphology, structure, chemical and electrochemical properties of the prepared materials were investigated. Chronopotentiometry (CP) and CV results show high specific capacitance of 186.2 to 298.4 F g?1 and the charge/discharge stability of the prepared materials and the ideal pseudocapacitive behaviors were observed. These results give an opening and promising application of these materials in advanced energy storage applications.

  3. Hydrogen reduction of cobalt ferrite

    SciTech Connect

    Porter, J.R.; de Jonghe, L.C.

    1981-06-01

    The kinetics of reduction of cobalt ferrite by hydrogen as a function of reduction temperature and pressure have been measured by thermogravimetric analysis. A minimum in the rate as a function of temperature has been observed and its cause attributed to the formation of a cobalt-wuestite subscale at higher reduction temperatures. A mathematical model, based on one derived by Spitzer, Manning, and Philbrook, has been used to interpret the results in terms of the rate constants for the individual steps in the reaction. Optical microscopy has been used to characterize the morphology of the reduction product and, additionally, partially reduced single crystals of cobalt ferrite have been examined by transmission electron microscopy to characterize the microstructure of the reaction interface. A fine network of pores in the reduced scale was shown to allow the reducing and product gases to reach the immediate vicinity of the chemical reaction. The structure of the porosity and consequently the effective diffusion coefficient in the scale were both shown to be functions of the reduction temperature and pressure. The interface reaction was shown to follow Langmuir-Hinshelwood kinetics. A model was developed to explain such kinetics by incorporating a solid-state diffusion step. Such a step was considered necessary to explain the development of the observed microstructures. An incubation time for the development of a continuous cobalt-wuestite subscale at higher reduction temperatures was attributed to the different growth kinetics for the spinel-metal and spinel-wuestite interfaces.

  4. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

    SciTech Connect

    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

    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.

  5. OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE

    E-print Network

    Sparks, Donald L.

    OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE by Brandon J MANGANESE OXIDE by Brandon J. Lafferty Approved..........................................................................................................1 Manganese Oxides...................................

  6. DNA templated magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kinsella, Joseph M.

    Recent discoveries in nanoscience are predicted to potentially revolutionize future technologies in an extensive number of fields. These developments are contingent upon discovering new and often unconventional methods to synthesize and control nanoscale components. Nature provides several examples of working nanotechnology such as the use of programmed self assembly to build and deconstruct complex molecular systems. We have adopted a method to control the one dimensional assembly of magnetic nanoparticles using DNA as a scaffold molecule. With this method we have demonstrated the ability to organize 5 nm particles into chains that stretch up to ˜20 mum in length. One advantage of using DNA compared is the ability of the molecule to interact with other biomolecules. After assembling particles onto DNA we have been able to cleave the molecule into smaller fragments using restriction enzymes. Using ligase enzymes we have re-connected these fragments, coated with either gold or iron oxide, to form long one-dimensional arrangements of the two different types of nanoparticles on a single molecular guide. We have also created a sensitive magnetic field sensor by incorporating magnetic nanoparticle coated DNA strands with microfabricated electrodes. The IV characteristics of the aligned nanoparticles are dependant on the magnitude of an externally applied magnetic field. This transport phenomenon known as tunneling magnetoresistance (TMR) shows room temperature resistance of our devices over 80% for cobalt ferrite coated DNA when a field of 20 kOe is applied. In comparison, studies using two dimensional nanoparticle films of irox oxides xii only exhibit a 35% MR effect. Confinement into one dimension using the DNA guide produces a TMR mechanism which produces significant increases in magnetoresistance. This property can be utilized for applications in magnetic field sensing, data storage, and logic elements.

  7. Effect of antisite formation on magnetic properties of nickel zinc ferrite particles

    NASA Astrophysics Data System (ADS)

    Ghosh, B.; Sardar, M.; Banerjee, S.

    2013-11-01

    In this report, we have investigated the effect of antisite ordering on the magnetic behavior of NixZn1-xFe2O4 nanoparticles for x = 0, 0.25, 0.5, 0.75, and 1. Observed magnetization versus temperature data show systematic gradual changes from antiferromagnetic to ferrimagnetic phase with increasing amount of Ni concentration. Saturation magnetization of the parent Zn ferrite increases when substituted by Ni and then decreases for concentration greater than x = 0.5. Coercivity also shows a concentration dependence. Saturation magnetization has no dependence on cooling field at all concentrations. For x = 0.5 the system act as an extremely soft magnetic material with highest saturation magnetization and lowest coercivity. Site occupancy by cations plays an important role for local moment imbalance between different antiferromagnetic sublattices giving rise to ferrimagnetic interaction upon Ni substituted in Zn ferrite.

  8. Manganese peroxidase gene transcription in Phanerochaete chrysosporium: activation by manganese.

    PubMed Central

    Brown, J A; Alic, M; Gold, M H

    1991-01-01

    The expression of manganese peroxidase in nitrogen-limited cultures of Phanerochaete chrysosporium is dependent on Mn, and initial work suggested that Mn regulates transcription of the mnp gene. In this study, using Northern (RNA) blot analysis of kinetic, dose-response, and inhibitor experiments, we demonstrate unequivocally that Mn regulates mnp gene transcription. The amount of mnp mRNA in cells of 4-day-old nitrogen-limited cultures is a direct function of the concentration of Mn in the culture medium up to a maximum of 180 microM. Addition of Mn to nitrogen-limited Mn-deficient secondary metabolic (4-, 5-, and 6-day-old) cultures results in the appearance of mnp mRNA within 40 min. The appearance of this message is completely inhibited by the RNA synthesis inhibitor dactinomycin but not by the protein synthesis inhibitor cycloheximide. Furthermore, the amount of mnp mRNA produced is a direct function of the concentration of added Mn. In contrast, addition of Mn to low-nitrogen Mn-deficient 2- or 3-day-old cultures does not result in the appearance of mnp mRNA. Manganese peroxidase protein is detected by specific immunoprecipitation of the in vitro translation products of poly(A) RNA isolated from Mn-supplemented (but not from Mn-deficient) cells. All of these results demonstrate that Mn, the substrate for the enzyme, regulates mnp gene transcription via a growth-stage-specific and concentration-dependent mechanism. Images PMID:2061289

  9. Magnetoelastic Villari effect in Mn Zn ferrites

    NASA Astrophysics Data System (ADS)

    Bie?kowski, Adam

    2000-06-01

    The relationship between magnetic induction B, and compressive stress - ? in Mn-Zn ferrites, of very low magnetostrictive constant ?s, were investigated. The Villari effect and its technical importance is discussed. It is shown that in Mn-Zn ferrites, with ?s?0, the Villari point occurs for ??0 and that these ferrites exhibit, for ? ?0 , considerable magnetoelastic sensitivity — in spite of their small ? s value. Hence, a low magnetostriction constant ?s does not exclude the possibility to apply such materials in magnetoelastic sensors.

  10. Hydrothermal Synthesis of Cobalt Ferrite Nanosized Powders

    NASA Astrophysics Data System (ADS)

    Zalite, I.; Heidemane, G.; Kuznetsova, L.; Maiorov, M.

    2015-03-01

    Cobalt ferrite powders are synthesized by the co-precipitation technology, combined with the hydrothermal synthesis method and crystallite size, specific surface area (SSA), magnetic properties of synthesized products are obtained. All the synthesized ferrites are nanocrystalline single phase materials with crystallite size of 10-16 nm the SSA of 60±5 m2/g and the calculated particle size of 20±2 nm. Synthesized Co ferrites are characterized by the saturation magnetization MS of 59-60 emu/g, remanent magnetization Mr of 23 emu/g and coercivity Hc of 570-650 Oe.

  11. Manganese biosorption sites of Saccharomyces cerevisiae.

    PubMed

    Parvathi, K; Nareshkumar, R; Nagendran, R

    2007-07-01

    Experiments conducted by pre-treating the fermentation industrial waste biomass of Saccharomyces cerevisiae with laboratory grade chemicals like formaldehyde-formic acid, ethanol, triethyl phosphite-nitromethane, dithiopyridine and benzene helped in studying the roles played by amines, carboxylic acids, phosphates, sulfhydryl group and lipids present on the cell wall of the biomass in manganese biosorption. Potentiometric titration of S. cerevisiae revealed the presence of carboxyl, phosphate, amine groups. The extent of the contribution of the functional groups and lipids to manganese biosorption was in the order: carboxylic acids > amines > lipids > phosphates. Blocking of sulfhydryl group did not have any significant effect on manganese uptake. PMID:17674651

  12. Iron and Manganese in Potable Water

    E-print Network

    Young, Clifford Caudy

    1911-06-01

    be treated in a number of ways. It can be heated and con­ verted to M n 3 O4, or dissolved in hydrochloric acid and precipitated as Mn NH 4 P 0 4 . This last has been worked (Ril over by Gibbs 'and by Gooch and Austin , all of whom pronounce it very... of Manganese 2. The precipitation of Manganese by means of (RS) ammonium carbonate we can dismiss at once as not being 4. available for water, for calcium and magnesium would be precipitated at the same time. 3. The precipitation of Manganese as MnOa hy...

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

    Microsoft Academic Search

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

    1986-01-01

    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,

  14. Preparation and magnetic properties of nano size nickel ferrite particles using hydrothermal method

    PubMed Central

    2012-01-01

    Background Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate) on the particles growth is investigated. Methods For investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and inductively coupled plasma atomic emission spectrometer (ICP-AES) techniques were used to characterize the samples. Results The results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature. Conclusions Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of NiFe2O4 nanoparticles decreased in comparison with surfactant- free prepared samples. All of the nickel ferrite nanoparticles were superparamagnetic at room temperature. Graphical abstract PMID:22462726

  15. Synthesis and assembly of high-quality cobalt ferrite nanocrystals prepared by a modified sol–gel technique

    Microsoft Academic Search

    Tal Meron; Yuri Rosenberg; Yossi Lereah; Gil Markovich

    2005-01-01

    Colloidal cobalt ferrite nanocrystals were produced using a new sol–gel-like synthesis based on the procedure developed by O’Brien et al. (J. Am. Chem. Soc. 123 (2001) 12085) for the synthesis of BaTiO3 nanocrystals. This synthesis involves the single-stage high-temperature hydrolysis of the metal alkoxide precursors to obtain crystalline, uniform, organically coated nanoparticles which are well-dispersed in an organic solvent. The

  16. Rietveld structure refinement of the cation distribution in ferrite fine particles studied by X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Gomes, J. A.; Sousa, M. H.; Tourinho, F. A.; Mestnik-Filho, J.; Itri, R.; Depeyrot, J.

    2005-03-01

    Samples of ZnFe2O4 and CuFe2O4 fine particles prepared by coprecipitation method have been studied by X-ray powder diffraction at room temperature. The oxygen position, the lattice parameter, the mean size of the nanoparticles and the cation distribution have been determined by means of Rietveld analysis, indicating the existence of mixed ferrites in both samples. These results are also evidenced through magnetic measurements in ferrofluid samples at room temperature.

  17. Flash microwave synthesis of trevorite nanoparticles

    SciTech Connect

    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

    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.

  18. Properties of ferrites at low temperatures (invited)

    NASA Astrophysics Data System (ADS)

    Dionne, Gerald F.

    1997-04-01

    At cryogenic temperatures magnetic properties of ferrites change significantly from their values at room temperature, which has been the main regime for most device applications. Recently, microwave ferrite devices with superconducting microstrip circuits have been demonstrated at a temperature of 77 K with virtually no electrical conduction losses. Conventional ferrimagnetic garnet and spinel compositions, however, are not generally optimized for low temperatures and may require chemical redesign if the full potential of these devices is to be realized. Saturation magnetizations increase according to the Brillouin-Weiss function dependence that is characteristic of all ferromagnetic materials. Increased magnetocrystalline anisotropy and magnetostriction can have large effects on hysteresis loop squareness and coercive fields that are essential for stable phase shift and efficient switching. Rare-earth impurities and other ions with short spin-lattice relaxation times can cause increased microwave losses. In this article, the basic magnetochemistry pertaining to ferrites will be examined for adaptation of ferrite technology to cryogenic environments.

  19. Ferrite HOM Absorber for the RHIC ERL

    SciTech Connect

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  20. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...Identity. The color additive manganese violet...be avoided by good manufacturing practice: Ash...filtrate of 10 grams color additive (shaken occasionally...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixture...

  1. 21 CFR 184.1446 - Manganese chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...ore (MnO2 ), or reduced manganese ore in hydrochloric acid. The resulting solution is neutralized to precipitate heavy metals, filtered, concentrated, and crystallized. (b) The ingredient meets the specifications of the Food...

  2. 21 CFR 184.1446 - Manganese chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...ore (MnO2 ), or reduced manganese ore in hydrochloric acid. The resulting solution is neutralized to precipitate heavy metals, filtered, concentrated, and crystallized. (b) The ingredient meets the specifications of the Food...

  3. 21 CFR 184.1446 - Manganese chloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...ore (MnO2 ), or reduced manganese ore in hydrochloric acid. The resulting solution is neutralized to precipitate heavy metals, filtered, concentrated, and crystallized. (b) The ingredient meets the specifications of the Food...

  4. HEALTH ASSESSMENT DOCUMENT FOR MANGANESE. FINAL REPORT

    EPA Science Inventory

    The document evaluates data on occurrence, sources, and transport of manganese in the environment and data on metabolism, pharmacokinetics, laboratory toxicological and epidemiologic studies to determine the nature and dose response relationship of potential health effects on hum...

  5. Synthesis of ultrafine grain ferrites

    E-print Network

    Livingston, Terry Wayne

    1988-01-01

    8. 0 mm I I I I I +-6. 1 nun~ I I I I I I I I I I I I I I I mm 4. 0 mm Figure 6. Type 1 Crucible 16. 2 nun 10 0 nim +. 0 niil'1 I I + 6. 1 lillrl W I I 1 I I I I / q~/ 40mni 2. 5 mm K ? al 4. 0 mlu Figure i. Type 2... and Jordan (1964) gave a typical series of steps in ferrite fabrication as: 1. Prepare raw materials. 2. Mix raw materials in proper ratio. 3. Fire the mixed constituents. 4. Mill the synthesized material. 5. Form the green body. 6. Sinter the green...

  6. Development and application of ferrite materials for low temperature co-fired ceramic technology

    NASA Astrophysics Data System (ADS)

    Zhang, Huai-Wu; Li, Jie; Su, Hua; Zhou, Ting-Chuan; Long, Yang; Zheng, Zong-Liang

    2013-11-01

    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.

  7. Sintering behaviour of cobalt ferrite ceramic

    Microsoft Academic Search

    A. Rafferty; T. Prescott; D. Brabazon

    2008-01-01

    Pure cobalt ferrite ceramic powder was prepared using standard solid-state ceramic processing. Uniaxially pressed pure cobalt ferrite discs, sintered under isothermal ramp rate and single dwell time conditions, yielded a maximum theoretical density (%Dth) of <90%. Discs made from finer particle size powder yielded a %Dth of 91.5%. Based on dilatometry analysis, a sintering profile comprising non-isothermal sintering, and two-step

  8. Spinwave spectrum for barium ferrite (abstract)

    Microsoft Academic Search

    S. P. Marshall; J. B. Sokoloff

    1990-01-01

    In order to determine whether barium ferrite will be suitable for microwave and millimeter wave device applications, it is essential to calculate the intrinsic ferrimagnetic resonance linewidth for perfect single crystals of this compound. The two mechanisms believed to be responsible for the intrinsic linewidth of barium ferrite, the Kasuya–LeCraw1 two-magnon one-phonon process and the two-magnon scattering caused by the

  9. Developments in soft magnetic power ferrites

    Microsoft Academic Search

    D. Stoppels

    1996-01-01

    Reduction in size and weight of power supplies can be achieved by using switched mode or resonant concepts at increasing frequencies, which may even exceed 1 MHz nowadays. For magnetic components this requires new ferrite grades with increasingly severe demands on low magnetic and eddy current losses. A well-balanced series of MnZn and NiZn power ferrites has been developed for

  10. Effects of Manganese Content on Solidification Structures, Thermal Properties, and Phase Transformation Characteristics in Fe-Mn-C Steels

    NASA Astrophysics Data System (ADS)

    Yang, Jian; Wang, Yu-Nan; Ruan, Xiao-Ming; Wang, Rui-Zhi; Zhu, Kai; Fan, Zheng-Jie; Wang, Ying-Chun; Li, Cheng-Bin; Jiang, Xiao-Fang

    2015-02-01

    The solidification structures and the thermal properties of Fe-Mn-C steel ingots containing different manganese contents have been investigated and the phase transformation characteristics have been revealed by Thermo-Calc to assist development of the continuous casting technology of Fe-Mn-C steels. The results show that the thermal conductivity of the 0Mn steel is higher than that of the 3Mn steel. The thermal conductivity of the 6Mn steel is the lowest in the three kinds of steels below 1023 K (750 °C) and the highest above 1173 K (900 °C). The 0Mn steel has the highest value of the proportion of equiaxed grain zone area in the three kinds of steels, whereas the 3Mn steel has the lowest value of it in the steels. Manganese has the effect of promoting the coarsening of grains. The microstructure is martensite and a little retained austenite (3.8 mass pct) in the 6Mn steel, whereas the microstructure is bainite in the 3Mn steel. The 0Mn steel is characterized by ferrite and pearlite. The mean thermal expansion coefficients of the steels are in the range from 1.0 × 10-5 to 1.6 × 10-5 K-1, and the determinations of mold tapers of the 6Mn and 3Mn steels can refer to low-carbon steel. Using RA <60 pct as the criterion, the third brittle temperature region of the 6Mn steel is 873 K to 1073 K (600 °C to 800 °C), whereas those of the 3Mn steel and the 0Mn steel are 873 K to 1123 K (600 °C to 850 °C) and 873 K to 1173 K (600 °C to 900 °C), respectively. In the 6Mn and 3Mn steels, the deformation-induced ferrite (DIF) forms in sufficient quantities cause the recovery of the ductility at the low temperature end. However, since low strains are present when straightening, sufficient quantities of DIF cannot be formed. Thus, the ductility of the 6Mn and 3Mn steels cannot be improved during the continuous casting process. Manganese has the effect of enlarging the austenite phase region and reducing the ?-ferrite phase region and ?-ferrite phase region.

  11. Toenail, Blood and Urine as Biomarkers of Manganese Exposure

    PubMed Central

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

    2011-01-01

    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

  12. Manganese recycling in the United States in 1998

    USGS Publications Warehouse

    Jones, Thomas S.

    2001-01-01

    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.

  13. Autonomic function in manganese alloy workers

    SciTech Connect

    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

    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.

  14. Magnesium and manganese content of halophilic bacteria.

    PubMed

    Médicis, E D; Paquette, J; Gauthier, J J; Shapcott, D

    1986-09-01

    Magnesium and manganese contents were measured by atomic absorption spectrophotometry in bacteria of several halophilic levels, in Vibrio costicola, a moderately halophilic eubacterium growing in 1 M NaCl, Halobacterium volcanii, a halophilic archaebacterium growing in 2.5 M NaCl, Halobacterium cutirubrum, an extremely halophilic archaebacterium growing in 4 M NaCl, and Escherichia coli, a nonhalophilic eubacterium growing in 0.17 M NaCl. Magnesium and manganese contents varied with the growth phase, being maximal at the early log phase. Magnesium and manganese molalities in cell water were shown to increase with the halophilic character of the logarithmically growing bacteria, from 30 mmol of Mg per kg of cell water and 0.37 mmol of Mn per kg of cell water for E. coli to 102 mmol of Mg per kg of cell water and 1.6 mmol of Mn per kg of cell water for H. cutirubrum. The intracellular concentrations of manganese were determined independently by a radioactive tracer technique in V. costicola and H. volcanii. The values obtained by Mn loading represented about 70% of the values obtained by atomic absorption. The increase of magnesium and manganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation. PMID:16347151

  15. Synthesis and characterization of multiferroic Bismuth Ferrite nanoparticles

    Microsoft Academic Search

    Maheshika Palihawadana Arachchige; Rajesh Regmi; Gavin Lawes

    2011-01-01

    In recent years, there has been considerable research in multiferroics, materials that exhibit more than one of ferroelectric, ferromagnetic and ferroelastic properties simultaneously. BiFeO3, as one of the very few mutiferroics with a simultaneous coexistence of ferroelectric and antiferromagnetic at room temperature, is among the most intensely studied and promising multiferroics. It has a rhombohedrally distorted pervokite structure and exhibits

  16. Novel magnetic SPE method based on carbon nanotubes filled with cobalt ferrite for the analysis of organochlorine pesticides in honey and tea.

    PubMed

    Du, Zhuo; Liu, Miao; Li, Gongke

    2013-10-01

    A novel magnetic SPE method based on magnetic cobalt ferrite filled carbon nanotubes (MFCNTs) coupled with GC with electron capture detection was developed to determine organochlorine pesticides (OCPs) in tea and honey samples. The MFCNTs were prepared through the capillarity of carbon nanotubes for drawing mixed cobalt and iron nitrates solution into their inner cavity followed by heating to 550°C under Ar to form the cobalt ferrite nanoparticles. SEM images provided visible evidence of the filled cobalt ferrite nanoparticles in the multiwalled nanotubes. X-ray photoelectron spectroscopy indicated no adhesion of cobalt ferrite nanoparticles and metal salts on the outer surface of the MFCNTs. Eight OCPs were extracted with the MFCNTs. The enrichment factors were in the range of 52-68 for eight OCPs. The LODs for the eight OCPs were in the range of 1.3-3.6 ng/L. The recoveries of the OCPs for honey and tea samples were 83.2-128.7 and 72.6-111.0%, respectively. The RSDs for these samples were below 6.8%. The new method is particularly suited to extract nonpolar and weakly polar analytes from a complex matrix and could potentially be extended to other target analytes. PMID:23926126

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

    NASA Astrophysics Data System (ADS)

    Narayanan, Badri Kannan

    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.

  18. Magnetic nanoparticles with combined anisotropy

    NASA Astrophysics Data System (ADS)

    Usov, N. A.; Barandiarán, J. M.

    2012-09-01

    We study the influence of the distribution of the particles' aspect ratio on the magnetostatic properties of an assembly of nanoparticles with cubic magnetocrystalline anisotropy, such as iron, nickel, iron oxides, and ferrites. Because of the large values of the dimensionless ratio Ms2/|Kc| for these particles, the shape anisotropy energy makes considerable contribution to the total nanoparticle energy even for relatively small shape distortions, with equivalent ellipsoids having aspect ratios ? ? 1.1. As a result, the magnetostatic properties of a randomly oriented assembly of particles with combined anisotropy at ? ? 1.1 are similar to those for an assembly of particles with purely uniaxial magnetic anisotropy. This conclusion is shown to be valid not only for the assembly hysteresis loops but also for the magnetic relaxation characteristics, at least in the high damping limit.

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

    NASA Technical Reports Server (NTRS)

    Aguilar, C.; Nealson, K. H.

    1998-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

    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).

  1. Rare earth influence on the structural and magnetic properties of NiZn ferrites

    NASA Astrophysics Data System (ADS)

    Jacobo, S. E.; Duhalde, S.; Bertorello, H. R.

    2004-05-01

    Nanoparticles of Zn 0.5Ni 0.5R 0.02Fe 1.98O 4 , with R=Y, Gd and Eu, have been prepared by the combustion method. Mössbauer spectroscopy has been used in order to analyse substitution effect on hyperfine parameters. A small increase in the hyperfine field parameters and a strong decrease of the total resonant area have been observed, with respect to the pure Ni-Zn ferrite. Curie temperatures decrease and coercive fields increase with substitution. The adding of much large ionic radii rare earth ions, results in local distortion and disorder, enough to induce a softening of the network.

  2. Influence of Nd Doping on Microwave Absorbing Properties of Nanocrystalline Ni-Zn Ferrites

    Microsoft Academic Search

    Haitao Zhao; Ruiting Ma; Gang Zhang; Xikun Li

    2011-01-01

    Nanoparticles of Ni0.5Zn0.5NdxFe2-xO4 ferrites with x = 0, 0.05 and 0.1 were successfully synthesized by the polyacrylamide gel method with acrylamide as monomer and N, N?-methylenediacrylamide as lattice agent. The structural characteristics, morphology and electromagnetic properties of the composite powders were obtained by X-ray diffraction (XRD), transmission electron microscope (TEM), thermogravimetric and differential thermal analysis (TG-DTA) and HP8510 network analyzer.

  3. Managing the manganese: molecular mechanisms of manganese transport and homeostasis.

    PubMed

    Pittman, Jon K

    2005-09-01

    Manganese (Mn) is an essential metal nutrient for plants. Recently, some of the genes responsible for transition metal transport in plants have been identified; however, only relatively recently have Mn2+ transport pathways begun to be identified at the molecular level. These include transporters responsible for Mn accumulation into the cell and release from various organelles, and for active sequestration into endomembrane compartments, particularly the vacuole and the endoplasmic reticulum. Several transporter gene families have been implicated in Mn2+ transport, including cation/H+ antiporters, natural resistance-associated macrophage protein (Nramp) transporters, zinc-regulated transporter/iron-regulated transporter (ZRT/IRT1)-related protein (ZIP) transporters, the cation diffusion facilitator (CDF) transporter family, and P-type ATPases. The identification of mutants with altered Mn phenotypes can allow the identification of novel components in Mn homeostasis. In addition, the characterization of Mn hyperaccumulator plants can increase our understanding of how plants can adapt to excess Mn, and ultimately allow the identification of genes that confer this stress tolerance. The identification of genes responsible for Mn2+ transport has substantially improved our understanding of plant Mn homeostasis. PMID:16101910

  4. Study of high performance alloy electroforming. [nickel manganese and nickel cobalt manganese alloys

    NASA Technical Reports Server (NTRS)

    Malone, G. A.

    1984-01-01

    Nickel-manganese alloy electrodeposits from an electrolyte containing more manganese ion than previously used is being evaluated at two bath operating temperatures with a great variety of pulse plating conditions. Saccharine was added as a stress reducing agent for the electroforming of several of the samples with highest manganese content. All specimens for mechanical property testing have been produced but are not through the various heat treatments as yet. One of the heat treatment will be at 343 C (650 F), the temperature at which the MCC outer electroformed nickel shell is stress relieved. A number of retainer specimens from prior work have been tested for hardness before and after heat treatment. There appears to be a fairly good correlation between hardness and mechanical properties. Comparison of representative mechanical properties with hardnesses are made for nickel-manganese electrodeposits and nickel-cobalt-manganese deposits.

  5. Influence of Aluminum Alloying and Heating Rate on Austenite Formation in Low Carbon-Manganese Steels

    NASA Astrophysics Data System (ADS)

    San Martín, D.; Palizdar, Y.; García-Mateo, C.; Cochrane, R. C.; Brydson, R.; Scott, A. J.

    2011-09-01

    This investigation focuses on the austenite formation process during continuous heating, over a wide range of heating rates (0.05 to 20 K/s), in three low carbon-manganese steels alloyed with different levels of aluminum (0.02, 0.48, and 0.94, wt pct Al). High resolution dilatometry, combined with metallographic observations, was used to determine the starting ( Ac 1) and finishing ( Ac 3) temperatures of this transformation. It is shown that both the aluminum content and the applied heating rate have a strong influence on this process. During fast heating (>1 K/s), the pearlite phase present in the initial microstructure remains almost unaffected up to temperature Ac 1. On the contrary, during slow heating, cementite lamellas inside pearlite partially dissolve, this dissolution effect being more pronounced for the lower carbon and higher aluminum content steels. The changes in the initial microstructure during slow heating affect the austenite nucleation and growth processes. Furthermore, in the aluminum alloyed steels, slow heating conditions shift the Ac 3 temperature to higher values. This shift is suggested to be due to aluminum partitioning from austenite to ferrite, which stabilizes ferrite and delays its transformation to higher temperatures. Thermodynamic calculations carried out with MTDATA software seem to support some of the experimental observations carried out under very low heating conditions close to equilibrium (0.05 K/s).

  6. Vanadia supported on nickel manganese oxide nanocatalysts for the catalytic oxidation of aromatic alcohols

    NASA Astrophysics Data System (ADS)

    Adil, Syed F.; Alabbad, Saad; Kuniyil, Mufsir; Khan, Mujeeb; Alwarthan, Abdulrahman; Mohri, Nils; Tremel, Wolfgang; Tahir, Muhammad Nawaz; Siddiqui, Mohammed Rafiq Hussain

    2015-02-01

    Vanadia nanoparticles supported on nickel manganese mixed oxides were synthesized by co-precipitation method. The catalytic properties of these materials were investigated for the oxidation of benzyl alcohol using molecular oxygen as oxidant. It was observed that the calcination temperature and the size of particles play an important role in the catalytic process. The catalyst was evaluated for its oxidation property against aliphatic and aromatic alcohols, which was found to display selectivity towards aromatic alcohols. The samples were characterized by employing scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller analysis, thermogravimetric analysis, and X-ray photoelectron spectroscopy.

  7. Vanadia supported on nickel manganese oxide nanocatalysts for the catalytic oxidation of aromatic alcohols.

    PubMed

    Adil, Syed F; Alabbad, Saad; Kuniyil, Mufsir; Khan, Mujeeb; Alwarthan, Abdulrahman; Mohri, Nils; Tremel, Wolfgang; Tahir, Muhammad Nawaz; Siddiqui, Mohammed Rafiq Hussain

    2015-01-01

    Vanadia nanoparticles supported on nickel manganese mixed oxides were synthesized by co-precipitation method. The catalytic properties of these materials were investigated for the oxidation of benzyl alcohol using molecular oxygen as oxidant. It was observed that the calcination temperature and the size of particles play an important role in the catalytic process. The catalyst was evaluated for its oxidation property against aliphatic and aromatic alcohols, which was found to display selectivity towards aromatic alcohols. The samples were characterized by employing scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller analysis, thermogravimetric analysis, and X-ray photoelectron spectroscopy. PMID:25852349

  8. Compressive Modulus of Ferrite Containing Polymer Gels

    NASA Astrophysics Data System (ADS)

    Mitsumata, Tetsu; Furukawa, Kenta; Juliac, Etienne; Iwakura, Kenji; Koyama, Kiyohito

    The mechanical properties of magnetic gel have been investigated. Magnetic gels, which consist of finely dispersed powder of barium ferrite (BaFe12O19) and poly vinyl alcohol (PVA), have been synthesized. The diameter of barium ferrite is less than 45 ?m. The magnetic gels varying with ferrite concentration, crosslinking densities were prepared by mixing 10 wt.% PVA aqueous solution and barium ferrite using glutaraldehyde as a crosslinking agent in the presence of HCl. The diameter of barium ferrite is large enough to have a permanent magnetic moment. We applied a 10 kOe magnetic field in order to saturate the magnetic moment of barium ferrite. After magnetization, the compressive modulus was estimated with an ultrasonic method in order to find the influence of magnetization. Ultrasonic measurements were carried out using burst waves at 10 MHz and 295.5 K. The modulus of magnetized gel was found to depend on the concentration of magnetic substance, the crosslinking density, and the degree of swelling. It was clear that the modulus of magnetized gel was higher than the gel without magnetization for all samples. The change in modulus to the initial modulus ?M'/M'o for 10 wt.% and 15 wt.% of ferrite concentration was about 0.28% and 0.4% in a lower density region, respectively. Moreover, the change in modulus ?M'/M'o was constant in a lower density region however it strongly depends on the density in a higher density region. When the stress direction is perpendicular to the magnetization, the change in modulus increased. On the contrary, the change in modulus decreased when the stress direction is parallel to the magnetization. As increasing the density, the distance between magnetic substances become short and therefore the magnetic interaction is more significant in a higher density region.

  9. Residual ferrite formation in 12CrODS steels

    NASA Astrophysics Data System (ADS)

    Ukai, S.; Kudo, Y.; Wu, X.; Oono, N.; Hayashi, S.; Ohtsuka, S.; Kaito, T.

    2014-12-01

    Increasing Cr content from 9 to 12 mass% leads to superior corrosion and high-temperature oxidation resistances, and usually changes microstructure from martensite to a ferrite. To make transformable martensitic type of 12CrODS steels that have superior processing capability by using ?/? phase transformation, alloy design was conducted through varying nickel content. The structure of 12CrODS steels was successfully modified from full ferrite to a transformable martensite-base matrix containing ferrite. This ferrite consists of both equilibrium ferrite and a metastable residual ferrite. It was shown that the fraction of the equilibrium ferrite is predictable by computed phase diagram and formation of the residual ferrite was successfully evaluated through pinning of ?/? interfacial boundaries by oxide particles.

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

    PubMed

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

    2013-08-01

    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

  11. Development of high frequency spice models for ferrite core inductors and transformers

    NASA Astrophysics Data System (ADS)

    Muyshondt, G. Patrick; Portnoy, William M.

    In this work high frequency SPICE models were developed to simulate the hysteresis and saturation effects of toroidal shaped ferrite core inductors and transformers. The models include the nonlinear, multi-valued B-H characteristic of the core material, leakage flux, stray capacitances, and core losses. The saturation effects were modeled using two diode clamping arrangements in conjunction with nonlinear dependent sources. Two possible controlling schemes were developed for the saturation switch. One of the arrangements used the current flowing through a series RC branch to control the switch, while the other used a NAND gate. The NAND gate implementation of the switch proved to be simpler and the parameters associated with it were easier to determine from the measurements and the B-H characteristics of the material. Lumped parameters were used to simulate the parasitic effects. Techniques for measuring these effects are described. The models were verified using manganese-zinc ferrite-type toroidal cores and they have general applicability to all circuit analysis codes equivalent function blocks such as multipliers, adders, and logic components.

  12. Manganese in dwarf spheroidal galaxies

    E-print Network

    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

    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 ...

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

    PubMed

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

    2012-02-22

    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

  14. Preparation of acicular NiZn-ferrite powders

    Microsoft Academic Search

    Yoshihiro Hayashi; Toshio Kimura; Takashi Yamaguchi

    1986-01-01

    Acicular NiZn-ferrite powder particles have been prepared from goethite-derived acicular Fe2O3 and spherical constituent oxides in the presence of molten chloride or sulphate. The morphology of NiZn-ferrite particles has been studied with reference to the effect of chemical species of molten salts, ferrite composition and particle size of constituent divalent oxides. Hence the best preparation conditions for acicular NiZn-ferrite powder

  15. Spindly cobalt ferrite nanocrystals: preparation, characterization and magnetic properties

    Microsoft Academic Search

    Xuebo Cao; Li Gu

    2005-01-01

    In this paper we describe the preparation of homogeneously needle-shaped cobalt ferrite (CoFe2O4) nanocrystals on a large scale through the smooth decomposition of urea and the resulting co-precipitation of Co2+ and Fe3+ in oleic acid micelles. Furthermore, we found that other ferrite nanocrystals with a needle-like shape, such as zinc ferrite (ZnFe2O4) and nickel ferrite (NiFe2O4), can be prepared by

  16. Globally sustainable manganese metal production and use.

    PubMed

    Hagelstein, Karen

    2009-09-01

    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

  17. Transformation kinetics and pathways of tetracycline antibiotics with manganese oxide

    E-print Network

    Huang, Ching-Hua

    Transformation kinetics and pathways of tetracycline antibiotics with manganese oxide Wan-Ru Chen 1 tetracyclines. Ã? 2011 Elsevier Ltd. All rights reserved. 1. Introduction Manganese, commonly present as Mn

  18. ) Composites Containing Nanoparticles and Larger Particles

    NASA Astrophysics Data System (ADS)

    Ghanaraja, S.; Nath, S. K.; Ray, S.

    2014-07-01

    The composites reinforced with nanoparticles result in improved strength and ductility while those containing coarser particles of micron size have limited ductility. The present study investigates the outcome of mechanical properties in a composite reinforced simultaneously with coarse and fine particles. High energy milling of manganese dioxide particles with excess of aluminum powder ensures that nanoparticles generated, either of MnO2 or alumina, are mostly separate and surrounded by aluminum particles. The milled powder when added to aluminum alloy melt, the excess aluminum particles will melt leaving behind separate oxide nanoparticles without significant agglomeration. Different amounts of milled powder mix have been stirred into molten aluminum alloy where nanoparticles of MnO2 react with melt to form alumina. The resulting slurry is cast into composites, which also contains coarser (nearly micron size) alumina particles formed by internal oxidation of the melt during processing. The microstructure of the composites shows good distribution of both the size categories of particles without significant clustering. The oxide particles are primarily ?-alumina in a matrix of aluminum-magnesium-manganese alloy containing some iron picked up from the stirrer. These composites fail during tensile test by ductile fracture due to debonding of coarser particles. The presence of nanoparticles along with coarser particles in a composite improves both strength and ductility considerably, presumably due to delay in debonding of coarser particles to higher stress because of reduced mismatch in extension caused by increased strain hardening in presence of nanoparticles in the matrix. The composites containing only coarser oxide particles show limited strength and ductility attributed to early debonding of particles at a relatively lower stress due to larger mismatch in extension between matrix and larger particles. Higher addition of powder mix beyond a limit, however, results in deterioration of mechanical properties, possibly due to clustering of nanoparticles. The present work, however, did not optimize the relative amounts of the different sized particles for achieving maximum ductility.

  19. A treatment of magnetized ferrites using the FDTD method

    Microsoft Academic Search

    J. A. Pereda; L. A. Vielva; A. Vegas; A. Prieto

    1993-01-01

    The finite-difference-time-domain (FDTD) method is extended to include magnetized ferrites. The treatment of the ferrite material is based on the equation of motion, using Gilbert's approximation of the damping term. The validity of the formulation is verified by applying it to the calculation of propagation constants in waveguides containing ferrites with transverse magnetization. The results for a rectangular waveguide filled

  20. Improvement of magnetomechanical properties of cobalt ferrite by magnetic annealing

    Microsoft Academic Search

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

    2005-01-01

    We report dramatic improvements in both magnetostriction level and strain derivative of polycrystalline cobalt ferrite as a result of magnetic annealing. Magnetostrictive cobalt ferrite composites have potential for use in advanced magnetomechanical stress and torque sensors due to their high sensitivity of magnetization to applied stresses and high levels of magnetostriction. Results show that annealing cobalt ferrite at 300°C in

  1. Neutron Diffraction Observation of Heat Treatment in Cobalt Ferrite

    Microsoft Academic Search

    E. Prince

    1956-01-01

    The effect on cobalt ferrite of heat treatment in a magnetic field has been studied by neutron diffraction. The data indicate that the magnetic moments are, in general, displaced from the directions which would be expected from consideration of crystalline anisotropy alone. The effect is greater in ferrites that are iron rich than it is in stoichiometric ferrites. The results

  2. AIMANTATION SPONTANE DES FERRITES Par REN PAUTHENET et L. BOCHIROL.

    E-print Network

    Paris-Sud XI, Université de

    également étudié la variation thermique de l'aimantation spontanée des ferrites de nickel, de cobalt et deAIMANTATION SPONTANÉE DES FERRITES Par RENÉ PAUTHENET et L. BOCHIROL. Sommaire. 2014 Les auteurs ont étudié les variations de l'aimantation à saturation des ferrites de magnésium et de cuivre en

  3. ANOMALIE DE LONGUEUR DES FERRITES Par LOUIS WEIL.

    E-print Network

    Paris-Sud XI, Université de

    ferrites de cuivre, de nickel, de cobalt, de zinc et de magnésium, entre la température ordinaire et 900° CANOMALIE DE LONGUEUR DES FERRITES Par LOUIS WEIL. Sommaire. - L'auteur a étudié la dilatation des étudié au dilatomètre Chevenard divers ferrites. Lorsqu'on fait varier la température assez lentement

  4. Advances in Engineering and Applications of Hexagonal Ferrites in Russia

    E-print Network

    Koledintseva, Marina Y.

    structure ­ hexagonal ferrites, or hexaferrites. The world`s first permanent magnets based on ferroxdure - hexagonal barium ferrite BaFe12O19 (equivalent to BaO6(Fe2O3), also called BaM) appeared in 1951 (Rathenaus, no ferrites with significant internal magnetic fields were available in the USSR. In 1958

  5. Properties and uses of barium ferrite ceramic magnets

    Microsoft Academic Search

    I. Yu. Gershov

    1963-01-01

    1.Barium ferrite is a promising ceramic material for permanent magnets. It does not include scarce and expensive materials. It has a low density and high coercive force; components with barium ferrite magnets therefore have high stability in operation, and high maximum specific magnetic energy, especially in anisotropic magnets.2.For the successful use of barium ferrite magnets it is essential to consider

  6. RF Thermal Plasma Synthesis of Ferrite Nanopowders from Metallurgical Wastes

    E-print Network

    Gubicza, Jenõ

    RF Thermal Plasma Synthesis of Ferrite Nanopowders from Metallurgical Wastes J.Szépvölgyi1 , I, thermal plasma, waste, XRD Abstract. RF thermal plasma synthesis of zinc-ferrite nanopowders has been that the saturation magnetization of ferrite powders produced by thermal plasma treatment was much higher than

  7. SYNTHESIS OF NANOSIZED ZINC FERRITES IN RF THERMAL PLASMA REACTOR

    E-print Network

    Gubicza, Jenõ

    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

  8. Magnetic properties of LiZnCu ferrite synthesized by the microwave sintering method

    NASA Astrophysics Data System (ADS)

    Khot, Sujata S.; Shinde, Neelam S.; Basavaiah, Nathani; Watawe, Shrikant C.; Vaidya, Milind M.

    2015-01-01

    Lithium ferrites have attracted considerable attention because they have been used as replacements for garnets due to their low cost. A series of polycrystalline ferrite samples were prepared with the composition of LiXZn(0.6-2X)Cu0.4Fe2O4(X=0.05, 0.1, 0.15, 0.2, 0.25, 0.3) at chemical reaction temperature 150 °C by sintering with microwave assisted combustion method. The characterization shows the formation of single phase cubic structure when carried out by using the X-rays technique and I-R technique. Magnetization parameters such as saturation magnetization, coercivity, magnetic moment were calculated by using the Hysteresis graph. The Curie temperature obtained using the susceptibility data are found to be in the range 350-700 °C. Anhysteric remanent magnetization is used for estimating the grain size and domain structure of the composition. An attempt has been made to synthesis the nano-particles at lower reaction temperature by using non-conventional microwave sintering method. The advantage of this method is its lower sintering temperature and time compared to the conventional ceramic technique and direct formation of nano-ferrites without ball-milling.

  9. (Data in thousand metric tons, gross weight, unless noted) Domestic Production and Use: Manganese ore containing 35% or more manganese was not produced domestically

    E-print Network

    Torgersen, Christian

    102 MANGANESE (Data in thousand metric tons, gross weight, unless noted) Domestic Production and Use: Manganese ore containing 35% or more manganese was not produced domestically in 1995. Manganese, and as a colorant for brick. Leading identifiable end uses of manganese were construction, machinery

  10. Small-angle neutron scattering investigation of the nanostructure of ferritic-martensitic 12%-chromium steels

    NASA Astrophysics Data System (ADS)

    Bogdanov, S. G.; Goshchitskii, B. N.; Parkhomenko, V. D.; Leontieva-Smirnova, M. V.; Chernov, V. M.

    2014-01-01

    The nanostructure (nanoparticle distribution) of ferritic-martensitic 12%-chromium steels EK-181 (Fe-12Cr-2W-V-Ta-B) and ChS-139 (Fe-12Cr-2W-V-Ta-B-Nb-Mo) subjected to different modes of mechanical and heat treatments and neutron irradiation has been investigated using small-angle neutron scattering. The samples have been studied in the initial state and after neutron irradiation (IVV-2M reactor) at a temperature of 80°C with fluences of 1018, 1019, and 5 × 1019 cm-2 ( E ? 0.1 MeV). The nanostructure of the steels is characterized by precipitations of nanoparticles with two characteristic sizes of 1.0-1.5 and 7-8 nm. The dependence of the nanostructure parameters on the composition of the steels and on the conditions of heat treatment and irradiation has been discussed.

  11. Original Research Manganese-Enhanced MRI Reveals Multiple

    E-print Network

    Duong, Timothy Q.

    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

  12. Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide. 2.

    E-print Network

    Sparks, Donald L.

    Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide. 2. Results from X-ray Absorption September 23, 2010. Accepted October 1, 2010. Arsenite (AsIII ) oxidation by manganese oxides (Mn Manganese-oxides (Mn-oxides) commonly occur as fine- grained particles or coatings in terrestrial

  13. Directed Vapor Deposition of Lithium Manganese Oxide Films

    E-print Network

    Wadley, Haydn

    Directed Vapor Deposition of Lithium Manganese Oxide Films A Dissertation Presented to the faculty the deposition of lithium manganese oxide films. Many phases with offering various electrochemical performance techniques. As-deposited lithium manganese oxide films grown on substrates at ambient temperature using high

  14. High manganese concentrations in rocks at Gale crater, Mars

    E-print Network

    High manganese concentrations in rocks at Gale crater, Mars Nina L. Lanza1 , Woodward W. Fischer2 to iron, manganese is sensitive only to high redox potential oxidants, and when concentrated in rocks on the Curiosity rover indicate abundances of manganese in and on some rock targets that are 1­2 orders

  15. 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

  16. EFFECT OF MANGANESE ON GROI,IIHOF SPHAEROTILUS

    E-print Network

    Luther, Douglas S.

    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

  17. NEUTRON SCATTERING AND CATION ROTATIONAL MOTION IN TETRAMETHYLAMMONIUM MANGANESE CHLORIDE

    E-print Network

    Paris-Sud XI, Université de

    473 NEUTRON SCATTERING AND CATION ROTATIONAL MOTION IN TETRAMETHYLAMMONIUM MANGANESE CHLORIDE B sample of tetramethylammonium manganese chloride has been measured for 0-500 cm-1energy transfers, both ammonium manganese chloride, (CH3)4MnCl3 exhibits the properties of a one-dimen- sional anti-ferro magnet

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

    E-print Network

    Winckler, Gisela

    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

  19. Kinetic Modeling of Oxidation of Antibacterial Agents by Manganese

    E-print Network

    Huang, Ching-Hua

    Kinetic Modeling of Oxidation of Antibacterial Agents by Manganese Oxide H U I C H U N Z H A N G demonstratedinearlierstudiestobehighlysusceptibletooxidation by manganese oxides, a common oxidant in soils. However, because of the high complexity of oxidative transformation of organic contaminants by manganese oxides in well-defined systems. Introduction

  20. Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide 1.

    E-print Network

    Sparks, Donald L.

    Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide 1. Stirred-Flow Experiments B R A N D O September 23, 2010. Accepted October 1, 2010. Manganese-oxides (Mn-oxides) are quite reactive, with respect of studying reaction mechanisms over time. Introduction Manganese-oxide minerals (Mn-oxides) are powerful