We report a facile one-pot chemical synthesis of colloidal FePt@Fe 3 O 4 core-shell nanoparticles... more We report a facile one-pot chemical synthesis of colloidal FePt@Fe 3 O 4 core-shell nanoparticles (NPs) with an average diameter of 8.7±0.4 nm and determine their compositional morphology, microstructure, two-dimensional strain, and magnetic hysteresis. Using various state-of-the-art analytical transmission electron microscopy (TEM) characterization techniques-including high resolution TEM imaging, TEM tomography, scanning TEM-high angle annular dark field imaging, and scanning TEM-energy dispersive x-ray spectroscopy elemental mapping-we gain a comprehensive understanding of the chemical and physical properties of FePt@Fe 3 O 4 NPs. Additional analysis using x-ray photoelectron spectroscopy, x-ray diffraction, and superconducting quantum interference device magnetometry distinguishes the oxide phase and determines the magnetic properties. The geometric phase analysis method is effective in revealing interfacial strain at the core-shell interface. This is of fundamental interest for strain engineering of nanoparticles for desirable applications. Abbreviations NPs Nanoparticles fcc Face-centred cubic XRD X-ray diffraction XPS X-ray photoelectron spectroscopy ICP-OES Inductively coupled plasma optical emission spectroscopy TEM Transmission electron microscopy STEM Scanning TEM
To assess cell death pathways in response to magnetic hyperthermia. Human melanoma cells were loa... more To assess cell death pathways in response to magnetic hyperthermia. Human melanoma cells were loaded with citric-acid-coated iron-oxide nanoparticles, and subjected to a time-varying magnetic field. Pathways were monitored in vitro in suspensions and in situ in monolayers using fluorophores to report on early-stage apoptosis and late-stage apoptosis and/or necrosis. Delayed-onset effects were observed, with a rate and extent proportional to the thermal-load-per-cell. At moderate loads, membranal internal-to-external lipid exchange preceded rupture and death by a few hours (the timeline varying cell-to-cell), without any measurable change in the local environment temperature. Our observations support the proposition that intracellular heating may be a viable, controllable and nonaggressive in vivo treatment for human pathological conditions.
2012 IEEE International Symposium on Signal Processing and Information Technology (ISSPIT), 2012
In the present digital world, Digital Rights Management (DRM) is essential to enforce persistent ... more In the present digital world, Digital Rights Management (DRM) is essential to enforce persistent data protection right from the moment it is published. In spite of a need for DRM there are significant weaknesses in the current technology. Generally, DRM system is achieved with individual function modules of cryptography, fingerprinting and so on. In this typical system flow, all digital contents are temporarily disclosed with perfect condition via decryption process. This paper describes the elemental idea of a DRM method which is composed of an incomplete cryptography based on permutation codes and user identification mechanism to control the quality of digital contents. There are two fundamental steps in our proposed cryptography: incomplete encoding and incomplete decoding. These two steps will create the scrambled content that is used as trial content and the fingerprinted content is used to prevent unauthorized duplication or business of digital contents, respectively. Experimental results on standard JPEG format show that the proposed method is suitable for DRM in the network distribution system.
Ferrimagnetic iron oxides are the common choice for many current technologies, especially those w... more Ferrimagnetic iron oxides are the common choice for many current technologies, especially those with application in biology and medicine. Despite the comprehensive knowledge accumulated about their chemistry in the bulk state, the sequence of changes taking place during the precipitation of iron oxide nanoparticles in aqueous media is much less extensive. We show that using sodium carbonate as a co-precipitating agent for the synthesis of uncoated iron oxide nanoparticles, the reaction proceeds sufficiently slowly to enable a detailed study of both the reaction pathway and products. The effect of pH, temperature and reaction time on particle size, morphology, crystalline phase and its magnetic properties was investigated. The obtained nanoparticles showed an increase in average particle size of about 10 nm per pH unit for the magnetite phase leading to 6.9 AE 0.4 nm, 18 AE 3 nm and 28 AE 5 nm for pH 8, 9 and 10 respectively. Goethite was initially formed by an olation mechanism at room temperature, followed by a slow transformation into magnetite over a 24 h period, as tracked by X-ray diffraction. In another set of experiments where the reaction temperatures were varied, magnetite was obtained directly by the oxolation mechanism at temperatures above 45 C. The optimization of the experimental parameters led to superparamagnetic nanoparticles with a high saturation magnetization of 82 A m 2 kg À1 at 300 K when synthesized at pH 9.
Ferromagnetic layer thickness dependence of anisotropic magnetoresistivities in Ta∕NiFe(t)∕IrMn (... more Ferromagnetic layer thickness dependence of anisotropic magnetoresistivities in Ta∕NiFe(t)∕IrMn (10 nm)∕Ta has been investigated for t=3, 4, 5, 7, 8, 10, 12, 15, and 20 nm by the method of anisotropic magnetoresistance and planar Hall effect. Our results revealed that the parallel and perpendicular resistivity components performed a varying function with increment in NiFe thickness. Both the resistivities at first
Annual Reports Section "A" (Inorganic Chemistry), 2010
This review summarises the advances in synthetic methods of nanoparticles (NPs) for biomedical ap... more This review summarises the advances in synthetic methods of nanoparticles (NPs) for biomedical applications published in 2009. Highlights The highlights of this review comprise the syntheses of magnetic NPs with tuneable shapes using simple procedures and by employing different reaction conditions. 7 Efforts have been made to modify the coating of NPs to allow them to respond to external stimuli. 9,10,49-53,126 Hollow structures 27-31 and NPs composed of noble metals 44 continue to be of interest. High quantum yield has been achieved in CdTe/CdSe semiconductor quantum dots. 99 Multimodal NPs with optical and magnetic properties continue to attract great interest and have been further developed. 125-130,132-134
We report a facile one-pot chemical synthesis of colloidal FePt@Fe 3 O 4 core-shell nanoparticles... more We report a facile one-pot chemical synthesis of colloidal FePt@Fe 3 O 4 core-shell nanoparticles (NPs) with an average diameter of 8.7±0.4 nm and determine their compositional morphology, microstructure, two-dimensional strain, and magnetic hysteresis. Using various state-of-the-art analytical transmission electron microscopy (TEM) characterization techniques-including high resolution TEM imaging, TEM tomography, scanning TEM-high angle annular dark field imaging, and scanning TEM-energy dispersive x-ray spectroscopy elemental mapping-we gain a comprehensive understanding of the chemical and physical properties of FePt@Fe 3 O 4 NPs. Additional analysis using x-ray photoelectron spectroscopy, x-ray diffraction, and superconducting quantum interference device magnetometry distinguishes the oxide phase and determines the magnetic properties. The geometric phase analysis method is effective in revealing interfacial strain at the core-shell interface. This is of fundamental interest for strain engineering of nanoparticles for desirable applications. Abbreviations NPs Nanoparticles fcc Face-centred cubic XRD X-ray diffraction XPS X-ray photoelectron spectroscopy ICP-OES Inductively coupled plasma optical emission spectroscopy TEM Transmission electron microscopy STEM Scanning TEM
To assess cell death pathways in response to magnetic hyperthermia. Human melanoma cells were loa... more To assess cell death pathways in response to magnetic hyperthermia. Human melanoma cells were loaded with citric-acid-coated iron-oxide nanoparticles, and subjected to a time-varying magnetic field. Pathways were monitored in vitro in suspensions and in situ in monolayers using fluorophores to report on early-stage apoptosis and late-stage apoptosis and/or necrosis. Delayed-onset effects were observed, with a rate and extent proportional to the thermal-load-per-cell. At moderate loads, membranal internal-to-external lipid exchange preceded rupture and death by a few hours (the timeline varying cell-to-cell), without any measurable change in the local environment temperature. Our observations support the proposition that intracellular heating may be a viable, controllable and nonaggressive in vivo treatment for human pathological conditions.
2012 IEEE International Symposium on Signal Processing and Information Technology (ISSPIT), 2012
In the present digital world, Digital Rights Management (DRM) is essential to enforce persistent ... more In the present digital world, Digital Rights Management (DRM) is essential to enforce persistent data protection right from the moment it is published. In spite of a need for DRM there are significant weaknesses in the current technology. Generally, DRM system is achieved with individual function modules of cryptography, fingerprinting and so on. In this typical system flow, all digital contents are temporarily disclosed with perfect condition via decryption process. This paper describes the elemental idea of a DRM method which is composed of an incomplete cryptography based on permutation codes and user identification mechanism to control the quality of digital contents. There are two fundamental steps in our proposed cryptography: incomplete encoding and incomplete decoding. These two steps will create the scrambled content that is used as trial content and the fingerprinted content is used to prevent unauthorized duplication or business of digital contents, respectively. Experimental results on standard JPEG format show that the proposed method is suitable for DRM in the network distribution system.
Ferrimagnetic iron oxides are the common choice for many current technologies, especially those w... more Ferrimagnetic iron oxides are the common choice for many current technologies, especially those with application in biology and medicine. Despite the comprehensive knowledge accumulated about their chemistry in the bulk state, the sequence of changes taking place during the precipitation of iron oxide nanoparticles in aqueous media is much less extensive. We show that using sodium carbonate as a co-precipitating agent for the synthesis of uncoated iron oxide nanoparticles, the reaction proceeds sufficiently slowly to enable a detailed study of both the reaction pathway and products. The effect of pH, temperature and reaction time on particle size, morphology, crystalline phase and its magnetic properties was investigated. The obtained nanoparticles showed an increase in average particle size of about 10 nm per pH unit for the magnetite phase leading to 6.9 AE 0.4 nm, 18 AE 3 nm and 28 AE 5 nm for pH 8, 9 and 10 respectively. Goethite was initially formed by an olation mechanism at room temperature, followed by a slow transformation into magnetite over a 24 h period, as tracked by X-ray diffraction. In another set of experiments where the reaction temperatures were varied, magnetite was obtained directly by the oxolation mechanism at temperatures above 45 C. The optimization of the experimental parameters led to superparamagnetic nanoparticles with a high saturation magnetization of 82 A m 2 kg À1 at 300 K when synthesized at pH 9.
Ferromagnetic layer thickness dependence of anisotropic magnetoresistivities in Ta∕NiFe(t)∕IrMn (... more Ferromagnetic layer thickness dependence of anisotropic magnetoresistivities in Ta∕NiFe(t)∕IrMn (10 nm)∕Ta has been investigated for t=3, 4, 5, 7, 8, 10, 12, 15, and 20 nm by the method of anisotropic magnetoresistance and planar Hall effect. Our results revealed that the parallel and perpendicular resistivity components performed a varying function with increment in NiFe thickness. Both the resistivities at first
Annual Reports Section "A" (Inorganic Chemistry), 2010
This review summarises the advances in synthetic methods of nanoparticles (NPs) for biomedical ap... more This review summarises the advances in synthetic methods of nanoparticles (NPs) for biomedical applications published in 2009. Highlights The highlights of this review comprise the syntheses of magnetic NPs with tuneable shapes using simple procedures and by employing different reaction conditions. 7 Efforts have been made to modify the coating of NPs to allow them to respond to external stimuli. 9,10,49-53,126 Hollow structures 27-31 and NPs composed of noble metals 44 continue to be of interest. High quantum yield has been achieved in CdTe/CdSe semiconductor quantum dots. 99 Multimodal NPs with optical and magnetic properties continue to attract great interest and have been further developed. 125-130,132-134
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