scholarly journals Size-Controlled Synthesis of CoFe2O4Nanoparticles Potential Contrast Agent for MRI and Investigation on Their Size-Dependent Magnetic Properties

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Fujun Liu ◽  
Sophie Laurent ◽  
Alain Roch ◽  
Luce Vander Elst ◽  
Robert N. Muller
Keyword(s):  
Magnetic Layer ◽  
Size Control ◽  
Correlation Spectroscopy ◽  
Local Concentration ◽  
Long Term Stability ◽  
Size Dependent ◽  
Transmission Electron ◽  
Size Controlled ◽  
Size Of Nuclei

Cobalt ferrite nanoparticles (CoFe2O4NPs) were synthesized by coprecipitation followed by treatments with diluted nitric acid and sodium citrate. Transmission electron microscope (TEM) and photon correlation spectroscopy (PCS) characterization showed that the size distributions of these nanoparticles were monodisperse and that no aggregation occurred. This colloid showed a long-term stability. Through adjustment of the concentrations of reactants and reaction temperature, the size of the NPs can be tuned from 6 to 80 nm. The size-control mechanism is explained by a nucleation-growth model, where the local concentration of monomers is assumed to decide the size of nuclei, and reaction temperatures influence the growth of nuclei. Magnetization and relaxivityr1,2measurements showed that the NPs revealed size-dependent magnetization and relaxivity properties, which are explained via a “dead magnetic layer” theory where reductions of saturation magnetization (Ms) andr1,2are assumed to be caused by the demagnetization of surface spins.

Synthesis and size control of Si nanocrystals by SiO/SiO2 superlattices and Er doping

2002 ◽  
Vol 737 ◽  
Author(s):  
J. Heitmann ◽  
D. Kovalev ◽  
M. Schmidt ◽  
L.X. Yi ◽  
R. Scholz ◽  
...  
Keyword(s):  
Phase Separation ◽  
Crystal Size ◽  
Radiative Lifetime ◽  
Size Control ◽  
Luminescence Signal ◽  
Er Doping ◽  
Size Dependent ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Ultrathin Layers

ABSTRACTThe synthesis of nc-Si by reactive evaporation of SiO and subsequent thermal induced phase separation is reported. The size control of nc-Si is realized by evaporation of SiO/SiO2 superlattices. By this method an independent control of crystal size and density is possible. The phase separation of SiO into SiO2 and nc-Si in the limit of ultrathin layers is investigated. Different steps of this phase separation are characterized by photoluminescence, infrared absorption and transmission electron microscopy measurements. The strong room temperature luminescence of nc-Si shows a strong blueshift of the photoluminescence signal from 850 to 750 nm with decreasing crystal size. Several size dependent properties of this luminescence signal, like decreasing radiative lifetime and increasing no-phonon transition properties with decreasing crystal size are in good agreement with the quantum confinement model. Er doping of the nc-Si shows an enhancement of the Er luminescence at 1.54 μm by a factor of 5000 compared to doped SiO2 layers. The decreasing transfer time for the nc-Si to Er transition with decreasing crystal size can be understood as additional proof of increasing recombination probability within the nc-Si for decreasing crystal size.

Synthesis of Trilaminar Core–Shell Au/α-Fe2O3@SnO2Nanocomposites and their Application for Nonenzymatic Dopamine Electrochemical Sensing

NANO ◽  
2019 ◽  
Vol 14 (11) ◽  
pp. 1950138 ◽  
Author(s):  
Sai Zhang ◽  
Shijun Yue ◽  
Jiajia Li ◽  
Jianbin Zheng ◽  
Guojie Gao
Keyword(s):  
Electron Microscopy ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Synthesis Process ◽  
Core Shell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Term Stability ◽  
Transmission Electron

Au nanoparticles anchored on core–shell [Formula: see text]-Fe2O3@SnO2 nanospindles were successfully constructed through hydrothermal synthesis process and used for fabricating a novel nonenzymatic dopamine (DA) sensor. The structure and morphology of the Au/[Formula: see text]-Fe2O3@SnO2 trilaminar nanohybrid film were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical properties of the sensor were investigated by cyclic voltammetry and amperometry. The experimental results suggest that the composites have excellent catalytic property toward DA with a wide linear range from 0.5[Formula: see text][Formula: see text]M to 0.47[Formula: see text]mM, a low detection limit of 0.17[Formula: see text][Formula: see text]M (S/[Formula: see text]) and high sensitivity of 397.1[Formula: see text][Formula: see text]A[Formula: see text]mM[Formula: see text][Formula: see text]cm[Formula: see text]. In addition, the sensor exhibits long-term stability, good reproducibility and anti-interference.

scholarly journals On Long-Term Stability of Metallic Glasses

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1076 ◽  
Author(s):  
Louzguine-Luzgin ◽  
Jiang
Keyword(s):  
Metallic Glasses ◽  
Surface Oxidation ◽  
Initial Structure ◽  
Ambient Conditions ◽  
Scanning Calorimetry ◽  
Long Term Stability ◽  
Transmission Electron ◽  
Different Types ◽  
Thermal Stability Of

Thermal stability of different types of metallic glasses and partially crystalline alloys stored for at least 15 years at ambient conditions was tested in the present work by differential scanning calorimetry in comparison with that of the original alloys tested in the as-cast state in the earlier works. The structure of the naturally aged alloys was also studied by X-ray diffractometry. The structure of a couple of selected alloys was also tested by transmission electron microscopy. Most of the alloys retained their initial structure and showed only a moderate decrease in the crystallization temperature. Only those alloys which showed visible surface oxidation (Cu-Zr-system based) were partly transformed into a crystalline state forming micron-scale Cu particles in air at ambient conditions.

scholarly journals Response of tropical stratospheric O<sub>3</sub>, NO<sub>2</sub> and NO<sub>3</sub> to the equatorial Quasi-Biennial Oscillation and to temperature as seen from GOMOS/ENVISAT

2010 ◽  
Vol 10 (4) ◽  
pp. 9153-9171 ◽  
Author(s):  
A. Hauchecorne ◽  
J. L. Bertaux ◽  
F. Dalaudier ◽  
P. Keckhut ◽  
P. Lemennais ◽  
...  
Keyword(s):  
Annual Variation ◽  
Local Concentration ◽  
Quasi Biennial Oscillation ◽  
Long Term Stability ◽  
Stellar Occultation ◽  
Ozone Monitoring ◽  
Dynamical Control ◽  
The Tropics ◽  
Biennial Oscillation

Abstract. The stellar occultation spectrometer GOMOS (Global Ozone Monitoring by Occultation of Stars) on ESA's Envisat satellite measures vertical profiles O3, NO2 and NO3 with a high long-term stability due to the self-calibrating nature of the technique. More than 6 years of GOMOS data from August 2002 to end 2008 have been analysed to study the inter-annual variation of O3, NO2 and NO3 in the tropics. It is shown that the QBO of the equatorial wind induces variations in the local concentration larger than 10% for O3 and larger than 25% for NO2. Quasi-Biennial Oscillation signals can be found in the evolution of the three constituents up to at least 45 km. We found that NO3 is positively correlated with temperature up to 40 km in the region where it is in chemical equilibrium with O3. Above 40 km, NO3 is no more in equilibrium during night and its concentration is correlated with both O3 and NO2. For O3 and NO2, our results confirm the existence of a transition from a dynamical control of O3 below 28 km with O3 correlated with NO2 and temperature and a chemical/temperature control between 28 and 38 km with O3 anti-correlated with NO2 and temperature. Above 38 km and up to 50 km a regime never described before is found with both O3 and NO2 anti-correlated with temperature. For the NO2/temperature anti-correlation, our proposed explanation is the modulation of the N2O ascent in the upper stratosphere by the QBO and the modulation of the Brewer-Dobson circulation. The oxidation of N2O is the main source of NOy in this altitude region. An enhancement of the ascending motion will cool adiabatically the atmosphere and will increase the amount of N2O concentration available for NOy formation.

THE SIZE CONTROL OF UNIFORM NANOCRYSTALLINE Si GRAINS BY CONSTRAINED GROWTH MODEL

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2751-2756 ◽  
Author(s):  
KUNJI CHEN ◽  
KAI CHEN ◽  
PEIGAO HAN ◽  
HECHENG ZOU ◽  
ZHONGYUAN MA ◽  
...  
Keyword(s):  
Size Control ◽  
Nanocrystalline Silicon ◽  
Annealing Conditions ◽  
Crystallization Method ◽  
Transmission Electron ◽  
Mean Size ◽  
Sublayer Thickness ◽  
The Mean ◽  
Size Controlled ◽  
Nanocrystalline Si

Size-controlled nanocrystalline silicon ( nc - Si ) has been prepared from a - SiN x / a - Si:H/a - SiN x ( 'a' standing for amorphous) sandwich structures by thermal annealing. Transmission electron microscope analyses show that the mean size and the grain size distribution (GSD) of the nc - Si are controlled by the annealing conditions and the a - Si sublayer thickness. Based on our theoretical model of constrained crystallization, we interpret the phenomena of the growth halt of nc - Si and higher crystallization temperature for the thinner a - Si sublayers. The experimental results show that constrained crystallization method is promising to achieve uniform and high density nc - Si array which can be used in the future nano-devices.

scholarly journals Fluorescent Submicron-Sized Poly(heptafluoro-n-butyl methacrylate) Particles with Long-Term Stability

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2013
Author(s):  
Maciej Jarzębski ◽  
Przemysław Siejak ◽  
Monika Przeor ◽  
Jacek Gapiński ◽  
Anna Woźniak ◽  
...  
Keyword(s):  
Reference Sample ◽  
Correlation Spectroscopy ◽  
Laser Scanning Microscopy ◽  
Submicron Particles ◽  
Butyl Methacrylate ◽  
Confocal Laser ◽  
Hydrodynamic Diameter ◽  
Term Stability ◽  
Long Term Stability

Fluorescent submicron particles of fluorinated methacrylate (HFMBA) with long-term stability have been synthesized and characterized with regard to their potential applications. Rhodamine B (RBITC) isothiocyanate was used as the fluorescent component. The core–shell structure of the particles effectively protected the dye against bleaching. HFBMA nanoparticle (NP) stability was confirmed after seven years of storage. Only slight differences were found in the polydispersity index (pdi) from 0.002 to 0.010. Particle size measurements were carried out using dynamic light scattering (DLS), nanoparticle tracking (NTA), and fluorescence correlation spectroscopy (FCS). The hydrodynamic diameter evaluated by different methods were in good agreement, respectively: 184–550 nm, 218–579 nm, and 236–508 nm. Particle and core morphology was estimated by using scanning and transmission electron microscopy (SEM and TEM). The ability to recognize particles in 3D as a reference sample in biological media has been confirmed by epifluorescence optical microscopy, confocal laser scanning microscopy, and super-resolution confocal microscopy (STED).

scholarly journals Preparation and Characterization of Size-Controlled Lignin Nanoparticles with Deep Eutectic Solvents by Nanoprecipitation

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 218
Author(s):  
Tong Luo ◽  
Chao Wang ◽  
Xingxiang Ji ◽  
Guihua Yang ◽  
Jiachuan Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Environmental Governance ◽  
Gel Permeation Chromatography ◽  
Deep Eutectic Solvents ◽  
High Yield ◽  
Long Term Stability ◽  
Self Assembling ◽  
Transmission Electron

Lignin nanomaterials have wide application prospects in the fields of cosmetics delivery, energy storage, and environmental governance. In this study, we developed a simple and sustainable synthesis approach to produce uniform lignin nanoparticles (LNPs) by dissolving industrial lignin in deep eutectic solvents (DESs) followed by a self-assembling process. LNPs with high yield could be obtained through nanoprecipitation. The LNPs were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). Distinct LNPs could be produced by changing the type of DES, lignin sources, pre-dropping lignin concentration, and the pH of the system. Their diameter is in the range of 20–200 nm and they show excellent dispersibility and superior long-term stability. The method of preparing LNPs from lignin–DES with water as an anti-solvent is simple, rapid, and environmentally friendly. The outcome aids to further the advancement of lignin-based nanotechnology.

scholarly journals Response of tropical stratospheric O<sub>3</sub>, NO<sub>2</sub> and NO<sub>3</sub> to the equatorial Quasi-Biennial Oscillation and to temperature as seen from GOMOS/ENVISAT

2010 ◽  
Vol 10 (18) ◽  
pp. 8873-8879 ◽  
Author(s):  
A. Hauchecorne ◽  
J. L. Bertaux ◽  
F. Dalaudier ◽  
P. Keckhut ◽  
P. Lemennais ◽  
...  
Keyword(s):  
Annual Variation ◽  
Local Concentration ◽  
Quasi Biennial Oscillation ◽  
Long Term Stability ◽  
Stellar Occultation ◽  
Ozone Monitoring ◽  
Dynamical Control ◽  
The Tropics ◽  
Biennial Oscillation

Abstract. The stellar occultation spectrometer GOMOS (Global Ozone Monitoring by Occultation of Stars) on ESA's Envisat satellite measures vertical profiles O3, NO2 and NO3 with a high long-term stability due to the self-calibrating nature of the technique. More than 6 years of GOMOS data from August 2002 to end 2008 have been analysed to study the inter-annual variation of O3, NO2 and NO3 in the tropics. It is shown that the QBO of the equatorial wind induces variations in the local concentration larger than 10% for O3 and larger than 25% for NO2. Quasi-Biennial Oscillation signals can be found in the evolution of the three constituents up to at least 40 km. We found that NO3 is positively correlated with temperature up to 45 km in the region where it is in chemical equilibrium with O3. Our results confirm the existence of a transition from a dynamical control of O3 below 28 km with O3 correlated with temperature and a chemical/temperature control between 28 and 38 km with O3 anti-correlated with NO2 and temperature. Above 38 km and up to 50 km a different regime is found with O3 and NO2 correlated with each other and anti-correlated with temperature. For the NO2/temperature anti-correlation in the upper stratosphere, our proposed explanation is the modulation of the N2O ascent by the QBO up to 45 km. The oxidation of N2O is the main source of NOy in this altitude region. An enhancement of the ascending motion will cool adiabatically the atmosphere and will increase the amount of N2O concentration available for NOy formation.

Parallel Formation of Three-Dimensional Spheroid Using Microrotational Flow

2010 ◽  
Vol 22 (5) ◽  
pp. 587-593 ◽  
Author(s):  
Hiroki Ota ◽  
◽  
Norihisa Miki
Keyword(s):  
Three Dimensional ◽  
Size Control ◽  
Biological Research ◽  
Single Chamber ◽  
Size Controlled ◽  
Chamber Diameter ◽  
Vitro Data ◽  
In Vitro Data

We propose three-dimensional (3D) spheroid formation involving perfusion and a lab-on-a-chip containing spheroid-forming chamber arrays. Cells are collected forming a spheroid in the chamber in microrotation. We previously reported a single chamber form hepatic spheroids 130 to 430 µm in diameter, controlling size by varying chamber diameter and cell density. Here, we scaled the system up by a factor of 10 while maintaining size control of 180±30 µm in diameter. Results were comparable to those using a single-chamber device. Long-term culture confirmed that cells in the spheroid maintained viability and diameters did not change after 24 hours. The system is readily applicable for creating size-controlled spheroids ensuring reliable, predictable in vitro data for drug screening and biological research.

scholarly journals Polyol-mediated synthesis of size-controlled copper nanoparticles under microwave irradiation

2019 ◽  
Vol 17 (12.1) ◽  
pp. 21
Author(s):  
Anh Trần Thị Kiều ◽  
Trung Đặng Bảo
Keyword(s):  
Microwave Irradiation ◽  
Copper Nanoparticles ◽  
Inductively Coupled Plasma ◽  
Size Control ◽  
X Ray Diffraction ◽  
Inductively Coupled ◽  
Transmission Electron ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Size Controlled

In this research, well-dispersed zero-valent copper nanoparticles (CuNPs) were successfully synthesized from a well-defined complex of [Cu(OH)(TMEDA)]2Cl2 in neat glycerol via a polyol method, under microwave irradiation (MW) assistance. The as-prepared CuNPs were thoroughly characterized by means of various techniques such as inductively coupled plasma mass spectrometry (ICP-MS), Ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses, evidencing the formation of the spherical nanoparticles with the range of 3.24.2 nm in mean diameter. In addition, the size control of obtained CuNPs was examined via reaction time, thereby showing that the formation of CuNPs conformed to the model of “mono-dispersion”.

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