► Cu ferrite nanoparticles were produced by a wet chemical method. ► Heat treatment was performed using an electric furnace. ► Tetragonal Cu ferrite with Jahn–Teller distortion or cubic structure was ...obtained, depending on the heat treatment method. ► X-ray absorption fine structure analysis was performed to support XRD measurements. ► The suppression and expression of the Jahn–Teller distortion seems to be dependent of the ambient pressure of the SiO2 cage.
Cu ferrite (CuFe2O4) nanoparticles were prepared by a wet chemical method. Heat treatment was performed using an electric furnace in an air atmosphere at temperatures between 973 and 1223K. Some samples were quenched after annealing; three different quenching methods were adopted. The particle diameters, as estimated from X-ray diffraction (XRD) patterns, ranged from 6 to 37nm. Tetragonal Cu ferrite with Jahn–Teller distortion or cubic Cu ferrite without Jahn–Teller distortion was obtained, depending on the heat treatment method used. X-ray absorption fine structure (XAFS) spectra supported the observed structural differences. Magnetization measurements were performed on each sample at a DC field of ±50kOe. The saturation magnetization of cubic Cu ferrite was greater than that of the distorted cubic structure.
To functionalize the surface of nanoparticles with phenyl groups for subsequent cross-linking with aromatic molecules by mutual interactions, we prepared functional nanoparticles (d = 3 nm) by ...silanization with phenyl-triethoxysilane. The nanoparticles had Fe2O3 cores conjugated to phenyl groups; this was confirmed by Fourier transform infrared (FT-IR) spectroscopy and absorption spectrophotometry. The typical C−H and C−C peaks and the absorption at 240 nm, which corresponds to aromatic rings, were detected in the spectroscopic results for the phenyl group-modified nanoparticles. The nanoparticles could ionize aromatic (colchicine, reserpine, and bradykinin peptide) and nonaromatic (l-α-phosphatidylethanolamine,dioleoyl, and polyethylene glycol) molecules by nanoparticle-assisted laser desorption/ionization mass spectrometry. The nanoparticles worked as a selective trap and an ionization-assisting reagent in mass spectrometry for the aromatic molecular targets.
We analyzed oligonucleotides by nanoparticle-assisted laser desorption/ionization (nano-PALDI) mass spectrometry (MS). To this end, we prepared several kinds of nanoparticles (Cr-, Fe-, Mn-, ...Co-based) and optimized the nano-PALDI MS method to analyze the oligonucleotides. Iron oxide nanoparticles with diammonium hydrogen citrate were found to serve as an effective ionization-assisting reagent in MS. The mass spectra showed both M - H(-) and M + xMe(2+)- H(-) (Me: transition metal) peaks. The number of metal-adducted ion signals depended on the length of the oligonucleotide. This phenomenon was only observed using bivalent metal core nanoparticles, not with any other valency metal core nanoparticles. Our pilot study demonstrated that iron oxide nanoparticles could easily ionize samples such as chemical drugs and peptides as well as oligonucleotides without the aid of an oligonucleotide-specific chemical matrix (e.g., 3-hydroxypicolinic acid) used in conventional MS methods. These results suggested that iron-based nanoparticles may serve as the assisting material of ionization for genes and other biomolecules.
Manganese oxide nanoparticles (Mn-O NPs) were prepared through our novel method as reagents for laser desorption/ionization mass spectrometry (LDI-MS). Through the control of the reaction time in the ...chemical preparation method (0.5, 1, and 5 h), we succeeded in preparing three different types of manganese oxide particles. The particles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and DC magnetization measurements. These characterization results indicated that the manganese ions oxidized in aqueous alkaline solution, and that the spinel structure was retained for the Mn3O4 phase, which then gradually changed into the MnO2 phase. The mass spectra of substance P (N.W. = 1347.6) were measured by PALDI-TOF mass spectrometry with Mn-O NPs. The Mn-O NPs that reacted with 3-aminopropyltriethoxysilane(γ-APTES) for 1 h or 5 h had higher ionization abilities than those reacted for 0.5 h. These different abilities are attributed to the different crystal structures of the prepared manganese oxides. DOI: 10.1380/ejssnt.2014.269
Magnetic nanoparticles were prepared by a wet chemical method. Precursors of
M
Fe
2
O
4
(
M
= Co, Mn, Zn) were prepared from a mixture of metal chloride and metasilicate nonahydrate aqueous ...solutions. The precipitates obtained in the wet chemical method were calcined to obtain
M
Fe
2
O
4
nanoparticles encapsulated by amorphous SiO
2
. The blocking temperatures
T
B
’s were between 20 and 320 K, in this temperature range, the anisotropy energy of the particles decreased below their thermal energy.
T
B
increased with the particle size. In order to clarify the nanoparticle formation process, differential thermal analysis and thermogravimetric (TG-DTA) measurements were performed for the as-prepared samples.
We synthesized magnetic nanoparticles (MNPs) by mixing aqueous solutions of 3d transition metal chlorides (MCl2·nH2O) and a sodium metasilicate nonahydrate (Na2SiO3·9H2O) in order to produce ...monodispersed MNPs in a single step. The particle size can be controlled by adjusting the annealing temperature. We characterized the MNPs by X-ray diffraction (XRD), superconducting quantum interference device (SQUID), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), and zeta-potential measurement. Paramagnetic and superparamagnetic behaviors were found for the obtained samples depending on the particle size (d=3.0–4.6 nm). The synthesized MNPs could be modified with the amino-, phenyl-, and carboxy- groups on MNPs' surface by silanization procedure, respectively. The purpose of functionalizing the surface of the nanoscale magnetic particles was to realize subsequent capture and detection with desired other molecules by nanoparticle assisted laser ionization/desorption mass spectrometry.
To quantify dose delivery errors for high-dose-rate image-guided brachytherapy (HDR-IGBT) using an independent end-to-end dose delivery quality assurance test at multiple institutions. The novelty of ...our study is that this is the first multi-institutional end-to-end dose delivery study in the world.
The postal audit used a polymer gel dosimeter in a cylindrical acrylic container for the afterloading system. Image acquisition using computed tomography, treatment planning, and irradiation were performed at each institution. Dose distribution comparison between the plan and gel measurement was performed. The percentage of pixels satisfying the absolute-dose gamma criterion was reviewed.
Thirty-five institutions participated in this study. The dose uncertainty was 3.6% ± 2.3% (mean ± 1.96σ). The geometric uncertainty with a coverage factor of k = 2 was 3.5 mm. The tolerance level was set to the gamma passing rate of 95% with the agreement criterion of 5% (global)/3 mm, which was determined from the uncertainty estimation. The percentage of pixels satisfying the gamma criterion was 90.4% ± 32.2% (mean ± 1.96σ). Sixty-six percent (23/35) of the institutions passed the verification. Of the institutions that failed the verification, 75% (9/12) had incorrect inputs of the offset between the catheter tip and indexer length in treatment planning and 17% (2/12) had incorrect catheter reconstruction in treatment planning.
The methodology should be useful for comprehensively checking the accuracy of HDR-IGBT dose delivery and credentialing clinical studies. The results of our study highlight the high risk of large source positional errors while delivering dose for HDR-IGBT in clinical practices.
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