Synthesis and characterization ofα-Fe2O3nanoparticles showing potential applications for sensing quaternary ammonium vapor at room temperature.

P-type and n-type metal oxide semiconductors are widely used in the manufacture of gas sensing materials, due to their excellent electronic, electrical and electrocatalytic properties. Hematite (α-Fe2O3) compound has been reported as a promising material for sensing broad types of gases, due to its affordability, good stability and semiconducting properties. In the present work, the efficient and easy-to-implement sol-gel method has been used to synthesizeα-Fe2O3nanoparticles (NPs). The TGA-DSC characterizations of the precursor gel provided information about the phase transformation temperature and the mass percentage of the hematite NPs. X-ray diffraction, transmission electron microscopy and x-ray photoelectron spectroscopy data analyses indicated the formation of two iron oxide phases (hematite and magnetite) when the NPs are subjected to thermal treatment at 400 °C. Meanwhile, only the hematite phase was determined for thermal annealing above 500 °C up to 800 °C. Besides, the crystallite size shows an increasing trend with the thermal annealing and no defined morphology. A clear reduction of surface defects, associated with oxygen vacancies was also evidenced when the annealing temperature was increased, resulting in changes on the electrical properties of hematite NPs. Resistive gas-sensing tests were carried out using hematite NPs + glycerin paste, to detect quaternary ammonium compounds. Room-temperature high sensitivity values (Sr âˆ¼ 4) have been obtained during the detection of ∼1 mM quaternary ammonium compounds vapor. The dependence of the sensitivity on the particle size, the mass ratio of NPs with respect to the organic ligand, changes in the dielectric properties, and the electrical conduction mechanism of gas sensing was discussed.

Effect of ultrasonic irradiation power on sonochemical synthesis of gold nanoparticles.

In this work, optimized size distribution and optical properties in the colloidal synthesis of gold nanoparticles (GNPs) were obtained using a proposed ultrasonic irradiation assisted Turkevich-Frens method. The effect of three nominal ultrasound (20 kHz) irradiation powers: 60, 150, and 210 W have been analyzed as size and shape control parameters. The GNPs colloidal solutions were obtained from chloroauric acid (HAuCl4) and trisodium citrate (C6H5Na3O7·2H2O) under continuous irradiation for 1 h without any additional heat or stirring. The surface plasmon resonance (SPR) was monitored in the UV-Vis spectra every 10 min to found the optimal time for localized SPR wavelength (λLSPR), and the 210 sample procedure has reduced the λLSPR localization at 20 min, while 150 and 60 samples have showed λLSPR at 60 min. The nucleation and growth of GNPs showed changes in shape and size distribution associated with physical (cavitation, temperature) and chemical (radical generation, pH) conditions in the aqueous solution. The results showed quasi-spherical GNPs as pentakis dodecahedron (λLSPR = 560 nm), triakis icosahedron (λLSPR = 535 nm), and tetrakis hexahedron (λLSPR = 525 nm) in a size range from 12 to 16 nm. Chemical effects of ultrasound irradiation were suggested in the disproportionation process, electrons of AuCl2- are rapidly exchanged through the gold surface. After AuCl4- and Cl- were desorbed, a tetrachloroaurate complex was recycled for the two-electron reduction by citrate, aurophilic interaction between complexes AuCl2-, electrons exchange, and gold seeds, the deposition of new gold atoms on the surface promoting the growth of GNPs. These mechanisms are enhanced by the effects of ultrasound, such as cavitation and transmitted energy into the solution. These results show that the plasmonic response from the reported GNPs can be tuned using a simple methodology with minimum infrastructure requirements. Moreover, the production method could be easily scalable to meet industrial manufacturing needs.

Magnetic domain interactions of Fe3O4 nanoparticles embedded in a SiO2 matrix.

Currently, superparamagnetic functionalized systems of magnetite (Fe3O4) nanoparticles (NPs) are promising options for applications in hyperthermia therapy, drug delivery and diagnosis. Fe3O4 NPs below 20 nm have stable single domains (SSD), which can be oriented by magnetic field application. Dispersion of Fe3O4 NPs in silicon dioxide (SiO2) matrix allows local SSD response with uniaxial anisotropy and orientation to easy axis, 90° <001> or 180° <111>. A successful, easy methodology to produce Fe3O4 NPs (6-17 nm) has been used with the Stöber modification. NPs were embedded in amorphous and biocompatible SiO2 matrix by mechanical stirring in citrate and tetraethyl orthosilicate (TEOS). Fe3O4 NPs dispersion was sampled in the range of 2-12 h to observe the SiO2 matrix formation as time function. TEM characterization identified optimal conditions at 4 h stirring for separation of SSD Fe3O4 in SiO2 matrix. Low magnetization (Ms) of 0.001 emu and a coercivity (Hc) of 24.75 Oe indicate that the embedded SSD Fe3O4 in amorphous SiO2 reduces the Ms by a diamagnetic barrier. Magnetic force microscopy (MFM) showed SSD Fe3O4 of 1.2 nm on average embedded in SiO2 matrix with uniaxial anisotropy response according to Fe3+ and Fe2+ electron spin coupling and rotation by intrinsic Neél contribution.

Protocolo de medición del balance articular del hombro en tenistas en sillas de ruedas / Articular range of motion protocol on shoulder joint over wheelchair tennis players

El presente estudio trata de aportar conocimiento científico útil para los fisioterapeutas acerca de la aplicación de un protocolo de medición de los balances articulares en la articulación glenohumeral sobre una población de tenistas en silla de ruedas. Así, se obtienen los descriptivos de todos los jugadores en valores angulares, aplicándose un análisis de fiabilidad, que refleja valores alpha de.76, y un análisis factorial, que ofrece valores de.902, como métodos para aportar validez estadística a los resultados. A partir de la valoración de los datos y de las conclusiones extraídas planteamos un tratamiento fisioterápico preventivo aplicable sobre lesiones producidas en esta articulación derivadas del exceso de elasticidad observado en los jugadores

This study is aimed to show science knowledge that could be used by physiotherapiest about an articular range of motion protocol on shoulder joint over wheelchair tennis players. In this way, it was obtained tennis players descriptives in angular values, applying a fiability analysis, which showed alpha values of.76 and a factorial analysis of.902, to prove the credibility of procurement values. Facts analysis was allowed us to pose a physical therapy treatment to prevent shoulder injuries that were caused by an excess of elasticity in tennis players analyzed

Current concepts in long QT syndrome.

Sudden cardiac death occurs in the United States with an incidence of more than 300,000 persons per year. The underlying cause of death is commonly considered to be due to primary or secondary arrhythmias. In young persons in whom no structural heart disease can be identified, the long QT syndromes (LQTS) are commonly considered as likely causes. Multiple genes causing LQTS have been identified thus far, all of which encode cardiac ion channels. These include two potassium channel alpha subunits (KVLQT1 and HERG), two potassium channel beta subunits (minK and MiRP1), and one sodium channel gene (SCN5A). The purpose of this review is to describe the current understanding of the molecular genetics of LQTS and the resultant phenotypes, particularly in young patients.

[Suprarenal hemangioma. Presentation of a case and review of the literature]. / Hemangioma suprarrenal. Presentación de un caso y revisión de la literatura.

Hemangiomas are benign vascular tumors that may present at any site and rarely in the adrenal gland. Twenty-four cases, all but one had been treated surgically, have been reported in the world literature. An additional case that had been diagnosed post-operatively is presented. The patient was submitted to surgery with the diagnosis of malignant neoplasm of the adrenal gland. This rare, benign tumor must be taken into account when making the differential diagnosis of adrenal masses. For this reason, it is necessary to be familiar with its clinical and radiologic features.