Authors:Dustin M. Clifford, Ahmed A. El-Gendy, Amos J. Lu, Dmitry Pestov, and Everett E. Carpenter
Cobalt nanoparticles were synthesized using continuous-flow (CF) chemistry in a stainless steel microreactor for the first time at high output based on the ethanol hydrazine alkaline system (EHAS) producing a yield as high as 1 g per hour [1, 2]. Continuous-flow (CF) synthetic chemistry provides uninterrupted product formation allowing for advantages including decreased preparation time, improved product quality, and greater efficiency. This successful synthetic framework in continuous-flow of magnetic Co nanoparticles indicates feasibility for scaled-up production. The average particle size by transmission electron microscopy (TEM) of the as-synthesized cobalt was 30±10 nm, average crystallite size by Scherrer analysis (fcc phase) was 15±2 nm, and the estimated magnetic core size was 6±1 nm. Elemental surface analysis (X-ray photoelectron spectroscopy [XPS]) indicates a thin CoO surface layer. As-synthesized cobalt nanoparticles possessed a saturation magnetization (Ms) of 125±1 emu/g and coercivity (Hc) of 120±5 Oe. The actual Ms is expected to be greater since the as-synthesized cobalt mass was not weight-corrected (nonmagnetic mass: reaction by-products, solvent, etc.). Our novel high-output, continuous-flow production (>1 g/hr) of highly magnetic cobalt nanoparticles opens an avenue toward industrial-scale production of several other single element magnetic nanomaterials.
Authors:Mircea Stefanescu, Marcela Stoia, Costica Caizer, Thomas Dippong, and Paul Barvinschi
This paper presents a study for the preparation of CoxFe3−xO4 (x = 0.02, 0.2, 0.5, 0.8, 1.0, 1.1, 1.5) nanoparticles, starting from metal nitrates: Co(NO3)2·6H2O, Fe(NO3)3·9H2O and ethylene glycol (C2H6O2). By heating the solutions metal nitrates-ethylene glycol, the redox reaction took place between the anion NO3− and OH–(CH2)2–OH with formation of carboxylate anions. The resulted carboxylate anions reacted with Co(II) and Fe(III) cations to form
coordinative compounds which are precursors for cobalt ferrite. XRD and magnetic measurements have evidenced the formation
of cobalt ferrite for all studied molar ratios. The average diameter of the cobalt ferrite crystallites was estimated from
XRD data and showed values in the range 10–20 nm. The crystallites size depends on the annealing temperature. The magnetization
of the synthesized samples depends on the molar ratio Co/Fe and on the annealing temperature.
Authors:Anjani Rundekar, P. Vrinda, and N. Sivaprasad
We have developed a simple one step ‘sandwich’ immunoradiometric assay for CA125 using monoclonal antibodies directed against
two different epitopes of the antigen. The detection antibody was radiolabeled with I-125 and the selected capture antibody
was chemically coupled to magnetizable cellulose to form immobilized solid support. In the developed inclusive assay procedure,
200 μL of standard or sample was incubated with 100 μL of radiolabeled and capture antibody suspension for 18 h at room temperature
with shaking. At the end of the incubation, the sandwich complex attached to solid phase is separated and counted for associated
radioactivity. The analytical sensitivity for the developed assay procedure was observed to be 3.0 U/mL with an assay range
up to 500 U/mL of CA125. The developed assay displayed acceptable precision; expressed in terms of percentage Coefficient
of Variation (CV) estimated by repeated analyses of the quality control samples. Intra-assay CV was observed to be less than
5% whereas inter-assay CV was also less than 6%. The analytical recovery of the developed assay observed to be in the range
of 88–107%. The clinical samples analyzed by the developed procedure showed a good correlation with that of a commercial kit
(r = 0.99; y = 1.0052x − 38.942).
using the blends of sulfoaluminate ferrite belite (SAFB) clinkers and ordinary
Portland cement (OPC) in mass ratio 85:15 with Al2O3,
and starch, polyphosphate (poly-P) or butylacrylate/acrylonitrile were subjected
to moist atmospheres (ambient, 52 and 100% relative humidity (RH)) to investigate
their moisture resistance. Their chemical, thermal, electron microscopic and
magnetic properties were also studied before and after moisture attack. Butylacrylate/acrylonitrile
(BA/AN) copolymer was found to be the most suitable for MDF cement synthesis
since the sample containing BA/AN showed the best moisture resistant. There
are significant differences in scanning electron microscopy (SEM) of MDF cements
before and after moisture attack and with different polymers. New data on
the paramagnetic nonhysteresis magnetization curves for all the samples are
observed. The MDF cements synthesized from SAFB clinker with dissolved poly-P
give the best signal/noise (S/N) ratio. Three main temperature regions on TG curves
of both series of MDF cements are observed. In the inter-phase section of
MDF cements, the content of classical cement hydrates decomposing by 250C
is increased. Combustion of organic material took place by 550C. In the
temperature range 550-800C, the decomposition of CaCO3
Thermal analysis, measurements of saturation magnetization and microstructure observations were used to determine the effects of silicon content (0<x<4.33 wt.%) on the liquidus-solidus temperatures, phase transformations and critical cooling rate during solutioning of Fe48−xCr28Co2xSix magnets. It was found that the addition of silicon on the investigated alloy (i) decreased the liquidus-solidus temperatures, the temperature changes for the solidus being greater than for the liquidus, and (ii) distinctly influenced the phase transition temperatures: The lower temperature of the range pfγ-phase existence and the Curie temperature decreased, theγ-phase region became narrower and theσ-phase region became slightly broader.
Authors:Rakesh K. Singh, A. Yadav, A. Narayan, Amrendra K. Singh, L. Verma, and R. K. Verma
materials. In the present study, effort has been made to choose the annealing temperature on the basis of the TG data. On all the chromite samples the magnetization and retentivity are very small as expected. However, coercivity was found to change as the
Pécsi ed., INQUA and IGCP P, 128, Budapest, 83--107.
Heller F, Márton E, Márton P 1979: Remanent Magnetization of a Pliensbachian Limestone Sequence at Bakonycsernye (Hungary). EOS (Trans. Am. Geophys. Union) , 60, 569
Authors:Ai-Yih Wang, Chun-Liang Kuo, Jiunn-Liang Lin, Chao-Ming Fu, and Yuh-Feng Wang
This study examined the applications of novel non-polymer magnetic ferrite nanoparticles (Fe3O4 NPs) labeled with 99mTc-pertechnetate (99mTcO4−). The radiochemistry, chemistry, and biodistribution of Fe3O4 NPs labeled with 9mTcO4− were analyzed. This paper employed instant thin layer chromatography and magnetic adsorption to evaluate the labeling efficiency
and stability of 99mTc-Fe3O4 at various reaction conditions. A scanning electron microscope, X-ray diffractometer, Fourier transform infrared spectrometer,
laser particle size analyzer, and superconducting quantum interference device magnetometer were used to analyze the physical
and chemical properties of the Fe3O4 and 99Tc-Fe3O4 nanoparticles. The biodistribution and excretion of 99mTc-Fe3O4 were also investigated. Radiochemical analyses showed that the labeling efficiency was over 92% after 1 min in the presence
of a reducing agent. Hydroxyl and amine groups covered the surface of the Fe3O4 particles. Therefore, 99Tc (VII) reduced to lower oxidation states and might bind to Fe3O4 NPs. The sizes of the 99Tc-Fe3O4 NPs were about 600 nm without ultrasound vibrations, and the particle sizes were reduced to 250 nm under ultrasound vibration
conditions. Nonetheless, Fe3O4 NPs and 99Tc-Fe3O4 NPs exhibited superparamagnetic properties, and the saturation magnetization values were about 55 and 47 emu/g, respectively.
The biodistribution showed that a portion of the 99mTc-Fe3O4 nanoparticles might embolize in a pulmonary capillary initially; the embolism radioactivity was cleared from the lungs and
was then taken up by the liver. 99mTc-Fe3O4 metabolized very slowly only 1–2% of the injected dose (ID) was excreted in urine and about 2.37% ID/g was retained in the
liver 4 h after injection. Radiopharmaceutically, 99mTc-Fe3O4 NPs displayed long-term retention, and only 99mTc-Fe3O4 NPs that dissociated to free pertechnetate could be excreted in urine. This research evaluated the feasibility of non-polymer
magnetic ferrite NPs labeled with technetium as potential radiopharmaceuticals in nuclear medicine.