Synthesis and characterization of nanocrystalline zinc ferrite

We report on the synthesis of highly uniform, single phase zinc ferrite films prepared through a single step low temperature reaction by the liquid phase deposition (LPD) method. X-ray diffraction, TGA and EDXmeasurements support the assumption that the as-deposited films are constituted from a mixture of crystallized FeOOH and amorphous Zn(OH)2. Upon heat treatment in air at 600 uC for one hour the intermediates are subsequently converted into the corresponding zinc ferrites. The films with adjustable chemical compositions are identified as having a spinel-type crystal structure and present a spherical or rod-like microstructure, depending on the Zn content. The magnetic films present a superparamagnetic behavior above blocking temperatures which decrease with increasing Zn content, and are ferromagnetic at 5 K with coercivities ranging between 797.8 and 948.5 Oe

Preparation, structural characterization, and dynamic properties investigation of permalloy antidot arrays

Regular nanosized structures are considered to be promising materials for magnetic information storage media with high density of information. Recently attention was paid to static and dynamic magnetic properties arising from dimensional confinement in such nanostructures. Here we present an investigation of permalloy antidot arrays of different thicknesses. Thin permalloy films of thickness ranging from 10 to 500 nm were deposited on anoporous Al2O3 membranes with a pore size of 100 nm. It was found that additional ferromagnetic resonance peaks appear for film thicknesses below 100 nm, while films with larger thicknesses show resonance properties similar to continuous films. A comparison between the films deposited onto Si wafers and porous media was done. An evolution of the domain structures observed in MFM experiments was confirmed by micromagnetic calculations

Fabrication of magnetic porous hollow silica drug carriers

Magnetic porous hollow silica nanosphere is a new class of structured nanomaterials for drug delivery. In this paper, we report a synthesis of magnetic porous hollow silica nanospheres MPHSNs using CaCO3 /Fe3O4 composite nanoparticles and cationic surfactant double templates. Fe3O4 nanoparticles were first mixed into CaCO3 using rotating packed bed forming CaCO3 /Fe3O4 composite nanoparticles. Tetraethoxysilane was then added as precursor to form silica layer on the surface of CaCO3 /Fe3O4 composite nanoparticles, while hexadecyltrimethylammonium bromide was used as a second template to direct the formation of porous silica shells. After the calcination of the surfactants and etching away CaCO3, MPHSNs were formed with the magnetite nanoparticles remaining in the cores. Transmission electron microscopy was applied for the nanostructure determination. The pore size can be measured by micromeritics analyzer. Magnetic properties ofMPHSNs were measured by a superconducting quantum interface device. Zero-field-cooled and field-cooled magnetization data in the temperature range of 5–300 K show that the MPHSNs are superparamagnetism above the blocking temperature and ferromagnetism below the blocking temperature after the calcination. The MPHSNs can be used as potential nanocarriers for targeted delivery and controlled releasing

Fabrication of magnetic porous hollow silica drug carriers

Magnetic porous hollow silica nanosphere is a new class of structured nanomaterials for drug delivery. In this paper, we report a synthesis of magnetic porous hollow silica nanospheres MPHSNs using CaCO3 /Fe3O4 composite nanoparticles and cationic surfactant double templates. Fe3O4 nanoparticles were first mixed into CaCO3 using rotating packed bed forming CaCO3 /Fe3O4 composite nanoparticles. Tetraethoxysilane was then added as precursor to form silica layer on the surface of CaCO3 /Fe3O4 composite nanoparticles, while hexadecyltrimethylammonium bromide was used as a second template to direct the formation of porous silica shells. After the calcination of the surfactants and etching away CaCO3, MPHSNs were formed with the magnetite nanoparticles remaining in the cores. Transmission electron microscopy was applied for the nanostructure determination. The pore size can be measured by micromeritics analyzer. Magnetic properties ofMPHSNs were measured by a superconducting quantum interface device. Zero-field-cooled and field-cooled magnetization data in the temperature range of 5–300 K show that the MPHSNs are superparamagnetism above the blocking temperature and ferromagnetism below the blocking temperature after the calcination. The MPHSNs can be used as potential nanocarriers for targeted delivery and controlled releasing

Annealing effects on the crystallite size and dielectric properties of ultrafine Ba1-xSrxTiO3 (0 \u3c x \u3c 1) powders synthesized through an oxalate-complex precursor

Nanocrystalline Ba12xSrxTiO3 (0 , x , 1) nanopowders were prepared through the oxalate route and the influence of the thermal history on their dielectric properties was investigated. For pelletized samples obtained by decomposing the corresponding oxalate intermediates at 600 uC and then annealed at different temperatures ranging from 600 to 1000 uC the dielectric constant decreases upon increasing the strontium content of the samples. Similar behavior was observed with decreasing the temperature of the thermal treatment of the pellets, a trend which is presumably ascribed to a synergic effect of decreasing the porosity of the samples, the increase of the crystallite size as well as the growth of nanograins. Additionally, a two-fold increase of the dielectric constant is also achievable by using a different annealing strategy, which consists of the direct heat treatment of the intermediates at different temperatures ranging between 600 and 1000 uC. In this latter case, the experimental data unambiguously show a direct correlation between the variation of the dielectric constant and that of the crystallite size/microstrain of the BSTO nanopowders

Ice Cream Truck Vendor Has Duty of Due Care to Protect His Minor Business Invitees; Whether He Breaches This Duty and, if So, Whether Such Breach Is the Proximate Cause of a Patron\u27s Injury Is a Fact Question, Precluding Summary Judgment.

Abstract Forthcoming

Magnetic Properties of Variable-sized Fe3O4 Nanoparticles Synthesized from Non-aqueous Homogeneous Solutions of Polyols

The magnetic behaviour of well-dispersed monodisperse Fe3O4 nanoparticles with sizes varying between 6.6 and 17.8 nm prepared in a non-aqueous medium was investigated. The smaller nanocrystals exhibit superparamagnetism with the blocking temperatures increasing with the particle size, whereas the biggest particles are ferromagnetic at room temperature. The saturation magnetization values are slightly smaller than that of the bulk material, suggesting the existence of a disordered spin configuration on their surface. The thickness of the magnetically inert shell was estimated from the size variation of the magnetization at 1.9 Å. The dipole–dipole interactions between the particles were tuned by changing the interparticle distances, e.g. by diluting the nanopowders in a non-magnetic matrix at concentrations ranging from 0.25 to 100 wt%. As the strength of the interactions is decreased with dilution, the energy barrier is substantially lowered; this will induce a drastic decrease of both the blocking temperatures and the coercivity with decreasing concentration of the nanoparticles

Magnetic Properties of Variable-sized Fe3O4 Nanoparticles Synthesized from Non-aqueous Homogeneous Solutions of Polyols

The magnetic behaviour of well-dispersed monodisperse Fe3O4 nanoparticles with sizes varying between 6.6 and 17.8 nm prepared in a non-aqueous medium was investigated. The smaller nanocrystals exhibit superparamagnetism with the blocking temperatures increasing with the particle size, whereas the biggest particles are ferromagnetic at room temperature. The saturation magnetization values are slightly smaller than that of the bulk material, suggesting the existence of a disordered spin configuration on their surface. The thickness of the magnetically inert shell was estimated from the size variation of the magnetization at 1.9 Å. The dipole–dipole interactions between the particles were tuned by changing the interparticle distances, e.g. by diluting the nanopowders in a non-magnetic matrix at concentrations ranging from 0.25 to 100 wt%. As the strength of the interactions is decreased with dilution, the energy barrier is substantially lowered; this will induce a drastic decrease of both the blocking temperatures and the coercivity with decreasing concentration of the nanoparticles

Pacioli, Popes, and the Bottom Billion: A Timeless Perspective on Economic Development

In 1494 Luca Pacioli, Franciscan friar, published Summa de Arithmetica Geometria Proportioni et Proportionalita (The Summa). Simply put, The Summa was an early business textbook comprised of five sections; four of mathematics and one of bookkeeping (or accounting). A textbook written to support the economic development of the common person of 1500 Italy. Today developing nations still struggle with economic (often low) growth. Especially impacted are the bottom billion, those who are still largely impoverished. Consequently, a debate over foreign aid has emerged. This debate centers on methods rather than objectives and is often characterized by the contrasting approaches. The books of Sachs (The End of Poverty, 2005) and Easterly (The White Man’s Burden, 2006) serve as a classic contrast of solution perspectives. This paper suggests a significant contribution to the economic development (aid) solution in the 500-year-old work of Luca Pacioli with its focus on developing human capital. The problems faced by an evolving merchant-based economy in 16th century Italy are surprisingly similar to those of contemporary developing economies, including the socially positive impacts of business and education’s role therein. Pacioli lists the elements of business success as access to capital (financing, mathematical and accounting skills), ability to model business and make business decisions, and an appropriate accounting system (“Venetian” or double entry bookkeeping). This paper argues these fundamentals are as important today and they were 500 years ago and considers them in the context of today’s emerging economies. In addition, Pacioli’s work integrates well with both various economic development theories and Catholic Social Teaching

Magnetic Characterization of Nanocrystalline Nickel Ferrite Films Processed by a Spin-Spraying Method

Highly crystalline nickel ferrite films with different chemical compositions were processed via the spin-spraying method and their morphological, structural and magnetic properties were subsequently investigated. Regardless of the chemical composition, films with variable thicknesses are constructed by 200–400 nm spherical grains grown in the direction normal to the substrate surface. Magnetization measurements show that the spinel ferrite films present a hysteretic behaviour at room temperature with a randomly oriented in-plane easy axis and an anisotropy constant K1 ≈ −2.5 × 104 erg cm−3 Furthermore, the absence of an angular dependence of the coercivity for the in-plane measurement of magnetization coupled with the ‘M’-shaped angular dependence of the out-of-plane measurement, indicates that the anisotropy of this film is predominantly crystalline shape anisotropy