scholarly journals Coating Effect on the 1H—NMR Relaxation Properties of Iron Oxide Magnetic Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1660
Author(s):  
Francesca Brero ◽  
Martina Basini ◽  
Matteo Avolio ◽  
Francesco Orsini ◽  
Paolo Arosio ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
1H Nmr ◽  
Nmr Relaxation ◽  
Force Microscopy ◽  
Fitting Procedure ◽  
Transmission Electron ◽  
Reversal Time ◽  
Two Samples ◽  
Means Of Transmission ◽  
Frequency Behavior

We present a 1H Nuclear Magnetic Resonance (NMR) relaxometry experimental investigation of two series of magnetic nanoparticles, constituted of a maghemite core with a mean diameter dTEM = 17 ± 2.5 nm and 8 ± 0.4 nm, respectively, and coated with four different negative polyelectrolytes. A full structural, morpho-dimensional and magnetic characterization was performed by means of Transmission Electron Microscopy, Atomic Force Microscopy and DC magnetometry. The magnetization curves showed that the investigated nanoparticles displayed a different approach to the saturation depending on the coatings, the less steep ones being those of the two samples coated with P(MAA-stat-MAPEG), suggesting the possibility of slightly different local magnetic disorders induced by the presence of the various polyelectrolytes on the particles’ surface. For each series, 1H NMR relaxivities were found to depend very slightly on the surface coating. We observed a higher transverse nuclear relaxivity, r2, at all investigated frequencies (10 kHz ≤ νL ≤ 60 MHz) for the larger diameter series, and a very different frequency behavior for the longitudinal nuclear relaxivity, r1, between the two series. In particular, the first one (dTEM = 17 nm) displayed an anomalous increase of r1 toward the lowest frequencies, possibly due to high magnetic anisotropy together with spin disorder effects. The other series (dTEM = 8 nm) displayed a r1 vs. νL behavior that can be described by the Roch’s heuristic model. The fitting procedure provided the distance of the minimum approach and the value of the Néel reversal time (τ ≈ 3.5 ÷ 3.9·10−9 s) at room temperature, confirming the superparamagnetic nature of these compounds.

scholarly journals Characterization of glycidyl methacrylate based magnetic nanocomposites

2019 ◽  
Vol 73 (1) ◽  
pp. 25-35
Author(s):  
Bojana Markovic ◽  
Vojislav Spasojevic ◽  
Aleksandra Dapcevic ◽  
Zorica Vukovic ◽  
Vladimir Pavlovic ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Magnetic Nanoparticles ◽  
Glycidyl Methacrylate ◽  
Mercury Porosimetry ◽  
Magnetic Nanocomposite ◽  
Magnetic Nanocomposites ◽  
Tem Analysis ◽  
X Ray ◽  
Force Microscopy ◽  
Transmission Electron

Magnetic and non-magnetic macroporous crosslinked copolymers of glycidyl methacrylate and trimethylolpropane trimethacrylate were prepared by suspension copolymerization and functionalized with diethylenetriamine. The samples were characterized by mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy analysis (FTIR-ATR), thermogravimetric analysis (TGA), X-ray diffractometry (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM) and SQUID magnetometry. The FTIR-ATR analysis of synthesized magnetic nanocomposites confirmed the presence of magnetite and successful amino- functionalization. Non-functionalized and amino-functionalized nanocomposites exhibited superparamagnetic behavior at 300 K, with a saturation magnetization of 5.0 emu/g and 2.9 emu/g, respectively. TEM analysis of the magnetic nanocomposite has shown that magnetic nanoparticles were homogeneously dispersed in the polymer matrix. It was demonstrated that incorporation of magnetic nanoparticles enhanced the thermal stability of the magnetic nanocomposite in comparison to the initial non-magnetic macroporous copolymer.

scholarly journals Synthesis and characterization of iron oxide magnetic nanoparticles

Nukleonika ◽  
2017 ◽  
Vol 62 (2) ◽  
pp. 73-77 ◽  
Author(s):  
Zbigniew Surowiec ◽  
Mieczysław Budzyński ◽  
Katarzyna Durak ◽  
Grzegorz Czernel
Keyword(s):  
Magnetic Nanoparticles ◽  
Ammonia Concentration ◽  
Blocking Temperature ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Iron Oxide Magnetic Nanoparticles ◽  
Means Of Transmission ◽  
Co Precipitation

Abstract Small particles of magnetite, i.e. 7.5, 13.4 and 14.1 nm in diameter, were obtained by the method of co-precipitation. The crystal structure and size distributions were determined by means of transmission electron microscopy and X-ray diffraction. The magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy within the temperature range from 3 K to room temperature (RT). The Mössbauer study of magnetic nanoparticles reveals relaxation behaviour related to the existence of the superparamagnetic phase. The blocking temperature depends on the sizes of the nanoparticles and the ammonia concentration.

Magnetic removal of nitrate ions from aqueous solution using amino-silica coated magnetic nanoparticles modified by oxovanadium(IV) porphyrin

2013 ◽  
Vol 17 (05) ◽  
pp. 359-366 ◽  
Author(s):  
Tahereh Poursaberi ◽  
Maryam Karimi ◽  
Mostafa Hassanisadi ◽  
Hassan Sereshti
Keyword(s):  
Magnetic Nanoparticles ◽  
Adsorption Selectivity ◽  
Maximum Sorption Capacity ◽  
Force Microscopy ◽  
Nitrate Ions ◽  
Atomic Force ◽  
Transmission Electron ◽  
Maximum Sorption ◽  
Spontaneous Regeneration ◽  
Modified Magnetic Nanoparticles

In this study, we have treated nitrate contaminated groundwater using modified magneticnanoparticles. The modification of magnetite nanoparticles were conducted by 3-aminopropyl-triethoxysilane followed by oxovanadium(IV) porphyrin in order to enhance the removal of nitrate ions. Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) were used to characterize the synthesized nanoparticles. The effect of pH, contact time, sorbent dosage and some co-existing anions present in aqueous solutions were investigated. The isothermal data of nitrate sorption conformed well to the Langmuir model and the maximum sorption capacity of nanosorbent for nitrate was 76.92 mg.g-1. Thermodynamic study indicated that the adsorption is endothermic and spontaneous. Regeneration of nitrate adsorbed material could be be possible by NaOH and the modified magnetic nanoparticles exhibited good reusability. The proposed system can provide a fast and efficient removal of the nitrate ion by using just an external magnetic field. The competitive adsorption tests verified that, this system has good adsorption selectivity for nitrate ions.

ANISOTROPIC GOLD NANOCRYSTALS: SYNTHESIS AND CHARACTERIZATION

2010 ◽  
Vol 24 (06n07) ◽  
pp. 757-761 ◽  
Author(s):  
R. STIUFIUC ◽  
F. TODERAS ◽  
M. IOSIN ◽  
G. STIUFIUC
Keyword(s):  
Growth Direction ◽  
Preferential Growth ◽  
Gold Nanocrystals ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Preferential Growth Direction ◽  
Phase Images ◽  
Means Of Transmission

In this letter we report on successful preparation and characterization of anisotropic gold nanocrystals bio-synthesized by reduction of aqueous chloroaurate ions in pelargonium plant extract. The nanocrystals have been characterized by means of Transmission Electron Microscopy (TEM), UV-VIS absorption spectroscopy and tapping mode atomic force microscopy (TM-AFM). Using these investigation techniques, the successful formation of anisotropic single nanocrystals with the preferential growth direction along the gold (111) plane has been confirmed. The high detail phase images could give us an explanation concerning the growth mechanism of the nanocrystals.

SYNTHESIS AND CHARACTERIZATION OF COBALT FERRITES MAGNETIC NANOPARTICLES IN ALKANETHIOL SOLUTION

2004 ◽  
Vol 03 (04n05) ◽  
pp. 639-648
Author(s):  
W. T. KERK ◽  
J. M. LI ◽  
W. S. CHIN ◽  
A. C. H. HUAN
Keyword(s):  
Electron Microscopy ◽  
Magnetic Nanoparticles ◽  
Size Distribution ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Homogeneous Solution ◽  
X Ray ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Cobalt Ferrites

Magnetic nanoparticles of cobalt ferrite have been synthesized in a homogeneous solution containing dodecanethiol at room temperature. The alkanethiol molecules have provided a mean to control the particle size distribution. The uniformed size distribution, crystallinity and morphology of these nanoparticles are characterized with X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The stoichiometry of the cobalt ferrite is confirmed by both elemental analysis and Energy Dispersive X-ray (EDX). Fabrication of assembled arrays of these nanoparticles on Si (100) have been achieved by slow evaporation of the solution and studied by Atomic Force Microscopy (AFM). Magnetic properties of the nanoparticles are determined by Vibrating Sample Magnetometer (VSM) and show a magnetization (Ms) of 75.3 emu/g and a coercivity (Hc) of 1500 Oe at room temperature.

scholarly journals Pinholes, Dislocations and Strain Relaxation in InGaN

1998 ◽  
Vol 3 ◽  
Author(s):  
B. Jahnen ◽  
M. Albrecht ◽  
W. Dorsch ◽  
S. Christiansen ◽  
H. P. Strunk ◽  
...  
Keyword(s):  
Critical Thickness ◽  
Strain Relaxation ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Slip Systems ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Wurtzite Lattice ◽  
Means Of Transmission

We analyse by means of transmission electron microscopy (TEM) and atomic force microscopy (AFM) the strain relaxation mechanisms in InGaN layers on GaN as dependent on the In content. At the experimentally given thickness of 100 nm, the layers remain coherently strained, up to an In concentration of 14 %. We show that part of the strain is reduced elastically by formation of hexagonally facetted pinholes. First misfit dislocations are observed to form at pinholes that reach the InGaN/GaN interface. We discuss these results in the framework of the Matthews-Blakeslee model for the critical thickness considering the Peierls force for glide of threading dislocations in the different slip systems of the wurtzite lattice.

Effect of Morphology on SnO2/MWCNT-Based DSSC Performance with Various Annealing Temperatures

2015 ◽  
Vol 1107 ◽  
pp. 649-654 ◽  
Author(s):  
Savisha Mahalingam ◽  
Huda Abdullah ◽  
Azimah Omar ◽  
Nurul Ain Md Nawi ◽  
Sahbudin Shaari ◽  
...  
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Photovoltaic Performance ◽  
Photocurrent Density ◽  
Open Circuit ◽  
Force Microscopy ◽  
Annealing Temperatures ◽  
Atomic Force ◽  
Transmission Electron ◽  
Means Of Transmission

Development of tin/multi-walled carbon nanotube (SnO2/MWCNTs) thin films were prepared by sol-gel method. The synthesis of tin oxide (SnO2) was carried out by dissolving tin (II) chloride (SnCl3) in a solvent of 2-methoxyethanol. Different annealing temperatures of 400 °C, 450 °C, 500 °C, 550 °C and 600 °C were proposed in this study. The changes in the structural properties were analyzed by means of transmission electron microscopy (TEM) and atomic force microscopy (AFM) analysis. AFM results indicated very rough surface area of SnO2/MWCNTs thin films where roughness values increased linearly from 1.8 nm to 11 nm by increasing the annealing temperatures from 400 °C to 600 °C. The SnO2/MWCNTs-based DSSC exhibited good photovoltaic performance with power conversion efficiency (η), photocurrent density (Jsc), open circuit voltage (Voc) and fill factor (FF) of 0.62 %, 5.6 mA cm-2, 0.55 V and 0.65 respectively. The obtained structural and photovoltaic performance analysis was proposed as a suitable benchmark for Sn/MWCNTs based dye-sensitized solar cell (DSSC) application.

Ultrastructural Analysis of the Salivary Glands of Gromphadorhina Portentosa (Schaum)

1977 ◽  
Vol 35 ◽  
pp. 638-639
Author(s):  
P.J. Dailey
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Salivary Glands ◽  
Secretory Vesicles ◽  
The Past ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Gromphadorhina Portentosa ◽  
Scanning Electron ◽  
Topographical Relief

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.

Ultrastructural investigation of an adenoma of the pituitary post mortem

1987 ◽  
Vol 45 ◽  
pp. 622-623
Author(s):  
Shirley Siew ◽  
W. C. deMendonca
Keyword(s):  
Deleterious Effect ◽  
Anterior Lobe ◽  
Definitive Diagnosis ◽  
Pars Intermedia ◽  
Post Mortem ◽  
Close Apposition ◽  
Autopsy Material ◽  
Progressive Loss ◽  
Transmission Electron ◽  
Means Of Transmission

The deleterious effect of post mortem degeneration results in a progressive loss of ultrastructural detail. This had led to reluctance (if not refusal) to examine autopsy material by means of transmission electron microscopy. Nevertheless, Johannesen has drawn attention to the fact that a sufficient amount of significant features may be preserved in order to enable the establishment of a definitive diagnosis, even on “graveyard” tissue.Routine histopathology of the autopsy organs of a woman of 78 showed the presence of a well circumscribed adenoma in the anterior lobe of the pituitary. The lesion came into close apposition to the pars intermedia. Its architecture was more compact and less vascular than that of the anterior lobe. However, there was some grouping of the cells in relation to blood vessels. The cells tended to be smaller, with a higher nucleocytoplasmic ratio. The cytoplasm showed a paucity of granules. In some of the cells, it was eosinophilic.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

Sign in / Sign up

Export Citation Format

Share Document