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A glass with the mol. % compositions 51.7 B2O3/9.3 K2O/1 P2O5/27.6 Li2O/10.4 Fe2O3 was crystallized at temperatures in the range from 400 to 540 °C for different periods of time (2-12 h). X-ray diffraction showed cubic Li ferrite with a spinel structure, LiFe5O8, with small crystallites with sizes in the range from 3 to 31 nm. While the samples crystallized at 440, 480, and 500 °C reveal a disordered phase, crystallization at 540 °C indicates a phase transformation to the ordered state. Magnetization curves showed that the samples crystallized at 440 °C are superparamagnetic with very low maximum magnetization, while the samples crystallized at 480 and 500 °C show thin clear S-shaped magnetization curves with zero coercivity and hence are also superparamagnetic. By contrast, the sample crystallized at 540 °C shows a coercive field of 40 Oe and thus is ferrimagnetic. The magnetic properties can be tailored by the size of the ferrite crystals and hence by the crystallization conditions. [ABSTRACT FROM AUTHOR]

Fe-substituted manganites Bi0.5Sr0.5FexMn1-xO3 (0≤x≤1.0) were synthesized by a solid-state reaction. X-ray powder diffraction and neutron diffraction investigations performed at room temperature show that the crystal structure is orthorhombic for x≤ 0.3 and cubic for x>0.4. The unit cell volume increases with x. Magnetic properties were studied between 5 and 1000 K in a magnetic field up to 16 kOe for the compounds with x≤0.7. A charge/orbital ordering feature was only observed in magnetization curves for the compound with no Fe. The magnetic state of the compounds with different Fe contents changes from paramagnetic to weak antiferromagnetic below the temperature TN varying in the range of 115–155 K. Unusual thermomagnetic behavior in the paramagnetic region was observed, which could be related to a coexistence of antiferromagnetic and ferromagnetic fluctuations far above TN. The typical thermomagnetic zero field cooled/field cooled hysteresis below about 40 K can be related to the formation of small ferromagnetic clusters below that temperature. The conductivity of the compounds, measured between 90 and 600 K, is of the semiconducting type, and no magnetoresistant effect was observed for any of them in a field of 7 kOe. [ABSTRACT FROM AUTHOR]

An experimental study was conducted to examine the basic magnetic properties of half-doped manganite with Fe substitution for Mn-[Bi.sub.0.5][Sr.sub.0.5][Fe.sub.x][Mn.sub.1-x][O.sub.3] (0(less than or equal to)x(less than or equal to)0.1). The conductivity of the compounds, measured between 90 and 600 K is found to be semiconducting type and no magnetoresistant effect was observed for any of the compound in a field of 7 kOe.

Co-Ni nanoparticles are synthesized through a chemical borohydride reduction with 0.2M NaBH4 in a mixture of water solutions of the chloride salts (0.1M CoCl2.6H2O and 0.1M NiCl2.6H2O) at a different Co: Ni ratio at room temperature in open lab space. Template synthesis of the same nanoparticles is carried out using graphite as a support in the presence of β-cyclodextin yielding carbon-containing nanocomposites. In the both cases of the synthesis it is experimented three ratios of Co: Ni=1:1, 4:1 and 1:4 to study the properties of these nanomaterials in connection with the influence of the different Co and Ni content. The morphology, the elemental, and phase composition are investigated by the help of Scanning electron microscopy (SEM), Energy dispersitive spectroscopy (EDS) and X-ray diffraction (XRD) analyses, respectively. Magnetic properties are also examined by the Vibrating Sample Magnetometer (VSM) at room temperature. In the all cases the particle morphology presents assemblies in size from 0.5 to 100 μm formed by nanopartilces due to the unsaturated nanosurface and magnetic forces. The Co-Ni nanoparticles are amorphous in structure. The different ratio of Co: Ni influences the Co and Ni content that is proved by the EDS analysis. The phases formed during the synthesis are also changed depending on the Co: Ni ratio. Co-Ni nanoparticles synthesized at Co: Ni=1:1 and 4:1 ratio have a soft ferromagnetic behavior. On the basis of the Saturation magnetization, Ms [emu/ g], the Co-Ni nanoparticles obtained at a ratio Co:Ni=1:1 and 4:1 have better magnetic characteristics than that in the case of a ratio Co:Ni=1:4 and also when graphite is used as asupport in the presence of β-cyclodextrin. These Co-Ni nanoparticle powders (Co:Ni=1:1 and 4:1) reveal a good ferromagnetic behavior, which would be suitable for biomedical applications as diagnostic tools and smart treatment agents in cancer and other diseases. [ABSTRACT FROM AUTHOR]

Glasses in the system 51.7 B2O3/9.3 K2O/1 P2O5/10.4 Fe2O3/(27.6 − y) MgO/y ZnO (with y = 0, 1, 2.5, 5, 7.5, 10, 13.8, and 20) were prepared by the conventional melt quenching method. The glass samples were thermally treated at 560 °C for 3 h in ambient conditions. Using 57Fe Mössbauer spectroscopy, the effect of the substitution of MgO by ZnO in the glass network and the effect on the precipitated crystallized phase was studied. The results showed that the ratio of Zn2+:Mg2+ in the precipitated crystals increases with the ZnO concentration in the glass. The isomer shift values indicated that iron occurs as Fe3+, which is distributed at the tetrahedral (A) and the octahedral [B] sites. Introducing ZnO leads to a relative increase of the Fe3+ concentration at the B sites at the expense of that occupying the A sites. This indicates the precipitation of ZnxMg1-x Fe2O4 nanoparticles, where Zn2+ ions favorably occupy the A sites. The average hyperfine field of the samples showed a strong dependence on the Zn concentration. At the highest Zn concentration of 13.8 and 20 mol%, the samples are paramagnetic, while for the smaller ones, the samples are superparamagnetic. [ABSTRACT FROM AUTHOR]

"Core/shell" composites are based on a ferrite core coated by two layers with different properties, one of them is an isolator, SiO 2 , and the other is a semiconductor, TiO 2 . These composites are attracting interest because of their structure, photocatalytic activity, and magnetic properties. Nanocomposites of the "core/shell" МFe 2 O 4 /SiO 2 /TiO 2 (М = Zn(II), Co(II)) type are synthesized with a core of MFe 2 O 4 produced by two different methods, namely the sol-gel method (SG) using propylene oxide as a gelling agent and the hydrothermal method (HT). SiO 2 and TiO 2 layer coating is performed by means of tetraethylorthosilicate, TEOS, Ti(IV) tetrabutoxide, and Ti(OBu) 4 , respectively. A combination of different experimental techniques is required to prove the structure and phase composition, such as XRD, UV-Vis, TEM with EDS, photoluminescence, and XPS. By Rietveld analysis of the XRD data unit cell parameters, the crystallite size and weight fraction of the polymorphs anatase and rutile of the shell TiO 2 and of the ferrite core are determined. The magnetic properties of the samples, and their activity for the photodegradation of the synthetic industrial dyes Malachite Green and Rhodamine B are measured in model water solutions under UV light irradiation and simulated solar irradiation. The influence of the water matrix on the photocatalytic activity is determined using artificial seawater in addition to ultrapure water. The rate constants of the photocatalytic process are obtained along with the reaction mechanism, established using radical scavengers where the role of the radicals is elucidated.

Novel composite hydrogels based on poly(acrylic acid-co-acrylamide)/polyacrylamide pseudo-interpenetrating polymer networks (pIPNs) and magnetite were prepared via in situ precipitation of Fe 3+ /Fe 2+ ions within the hydrogel structure. The magnetite formation was confirmed by X-ray diffraction, and the size of the magnetite crystallites was shown to depend on the hydrogel composition: the crystallinity of the magnetite particles increased in line with PAAM content within the composition of the pIPNs. The Fourier transform infrared spectroscopy revealed an interaction between the hydrogel matrix, via the carboxylic groups of polyacrylic acid, and Fe ions, which strongly influenced the formation of the magnetite articles. The composites' thermal properties, examined using differential scanning calorimetry (DSC), show an increase in the glass transition temperature of the obtained composites, which depends on the PAA/PAAM copolymer ratio in the pIPNs' composition. Moreover, the composite hydrogels exhibit pH and ionic strength responsiveness as well as superparamagnetic properties. The study revealed the potential of pIPNs as matrices for controlled inorganic particle deposition as a viable method for the production of polymer nanocomposites.

An intraluminal duodenal diverticulum (IDD) is a rare congenital anomaly, which is a result of incomplete recanalization of the foregut lumen during embryonic development. Most patients are asymptomatic. Symptoms usually occur after the third decade of life and mainly include epigastric pain, nausea, vomiting, or bloating. Less commonly, IDD may complicate with bleeding, duodenal obstruction, or acute pancreatitis. We present a case of IDD, manifested for a first time in adult with acute biliary obstruction and mild pancreatitis after laparoscopic cholecystectomy for acute calculous cholecystitis, successfully managed with endoscopic retrograde cholangiopancreatography (ERCP).