The structural and magnetic properties of nanocrystalline manganese, cobalt, and nickel spinel ferrites dispersed in a highly porous SiO 2 aerogel matrix were studied. X-ray diffraction and high-resolution transmission electron microscopy indicate that single crystalline ferrite nanoparticles are well dispersed in the amorphous matrix. The cation distribution between the octahedral and tetrahedral sites of the spinel structure was investigated by X-ray absorption spectroscopy. The analysis of both the X-ray absorption near edge structure and the extended X-ray absorption fine structure indicates that the degree of inversion of the spinel structure increases in the series Mn, Co, and Ni spinel, in accordance with the values commonly found in the corresponding bulk spinels. In particular, fitting of the EXAFS data indicates that the degree of inversion in nanosized ferrites is 0.20 for MnFe 2 O 4 , 0.68 for CoFe 2 O 4 , and 1.00 for NiFe 2 O 4 . Magnetic characterization further supports these findings.

The intercalation of lithium in nanosized TiO2 has been studied for its application as an electrode for rechargeable Li-ion batteries. In this paper, we use a synthesis process in order to obtain a low-density anatase TiO2 presenting monocrystalline particles of 7−8 nm. These textural characteristics allow this material to host almost twice as much Li (300 mAh·g−1) than that of a micrometer sized anatase. In this study, in situ X-ray absorption spectroscopy is used to monitor and understand the structural changes that happen upon lithium insertion/removal, leading to a reversible two-phase transition process: TiO2 (I41/amd) → Li-titanate (Imma) → Li1TiO2 (I41/amd).

Objective: Obesity is frequently associated with modifications of thyroid size and function. We evaluated the prevalence of thyroid function abnormalities and the effects of puberty and weight loss in obese children and adolescents. Methods: We examined 468 obese children (255 girls and 213 boys aged 3.7–17.9 years) and 52 normal-weight age-matched children as controls. TSH, fT3, fT4, fasting serum insulin and glucose were measured at baseline. fT3, fT4 and TSH were also measured after 6 months of lifestyle intervention in a subset of 43 patients. Results: 109 obese children showed abnormal circulating thyroid hormone concentrations (84 had elevated fT3 levels, 15 elevated TSH, 6 elevated fT4, 3 elevated fT3 and TSH, and 1 elevated fT3, fT4 and TSH levels). Serum TSH and fT3 concentrations were positively correlated with BMI-SDS. The prevalence of patients with abnormal thyroid hormone concentrations was similar between sexes and between prepubertal and pubertal subjects. After 6 months of lifestyle intervention, thyroid hormone concentrations normalized in 27 of the patients with decreased BMI-SDS, and in 2 patients in whom BMI-SDS increased. Conclusions: In obese children, an increased fT3 concentration is the most frequent thyroid function abnormality. Serum fT3 and TSH correlate with BMI. Moderate weight loss frequently restores these abnormalities.

In this paper we review an interesting method of PET recycling, i.e. chemical recycling; it is based on the concept of depolymerizing the condensation polymer through solvolytic chain cleavage into low molecular products which can be purified and reused as raw materials for the production of high-quality chemical products. In this work our attention is confined to the hydrolysis (neutral, acid and alkaline) and glycolysis processes of PET chemical recycling; operating conditions and mechanism of each method are reported and described. The neutral hydrolysis has an auto accelerating character; two kinetic models have been proposed: an half-order and a second order kinetic model. The acid hydrolysis could be explained by a modified shrinking core model under chemical reaction control and the alkaline hydrolysis by a first-order model with respect to hydroxide ion concentration. To describe glycolysis, two different kinetic models have been proposed where EG can act or not as internal catalyst. Further experimental and theoretical investigations are required to shed light on the promising processes of PET chemical recycling reviewed in this work.

We present a study of the structural, magnetic, and magneto-optical properties of a series of Co-substituted ferrite nanoparticles (NPs) prepared by thermal decomposition of metallo-organic precursors in high boiling solvents. The structural characterization, carried out by using several techniques (transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and magnetic circular dichroism measurements), showed all the samples are high crystalline, 5–6 nm spherical NPs with the cubic spinel structure typical of ferrites. The evolution of lattice parameters with cobalt content suggests that the material is Co-substituted maghemite, also confirmed by XAS and magneto optical (MO) characterizations. The investigation of the magnetic and magneto-optical properties displays peculiar trends with the cobalt content, the main features being the large increase of the saturation magnetization and the anomalous dependence of magnetic anisotropy which reaches its maximum values for intermediate compositions. The large tuneability of this material makes it possible to implement the performances of devices used in biomedical and sensing applications

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. (2005) Sol-gel synthesis of the P2O5-CaO-Na2O-SiO2 system as a novel bioresorbable glass. Journal of Materials Chemistry, 15 (21).