Development of an Ultra-Low Carbon MgO Refractory Doped with α-Al2O3 Nanoparticles for the Steelmaking Industry: A Microstructural and Thermo-Mechanical Study.

The effect of α-Al2O3 nanoparticles (up to 5 wt.%) on the physical, mechanical, and thermal properties, as well as on the microstructural evolution of a dense magnesia refractory is studied. Sintering temperatures at 1300, 1500, and 1600 °C are used. The physical properties of interest were bulk density and apparent porosity, which were evaluated by the Archimedes method. Thermal properties were examined by differential scanning calorimetry. The mechanical behavior was studied by cold crushing strength and microhardness tests. Finally, the microstructure and mineralogical qualitative characteristics were studied by scanning electron microscopy and X-ray diffraction, respectively. Increasing the sintering temperature resulted in improved density and reduced apparent porosity. However, as the α-Al2O3 nanoparticle content increased, the density and microhardness decreased. Microstructural observations showed that the presence of α-Al2O3 nanoparticles in the magnesia matrix induced the magnesium-aluminate spinel formation (MgAl2O4), which improved the mechanical resistance most significantly at 1500 °C.

Copper antimony sulfide thin films for visible to near infrared photodetector applications.

Ternary chalcostibite copper antimony sulfide (CuSbS2) is an emerging semiconductor material having applications in photovoltaics, energy storage and optoelectronics due to its high absorption coefficient, suitable bandgap, and it consists of non-toxic and earth abundant elements. CuSbS2 thin films are prepared by combining chemical bath deposition (antimony sulfide (Sb2S3)) and thermal evaporation (copper (Cu)) followed by a heat treatment and their application as visible to near infrared photodetectors is reported. Crystalline structure, elemental composition, chemical state, morphology and optoelectronic properties of the films were characterized by various techniques. The effect of three different Cu thicknesses (CAS 20, CAS 30 and CAS 40 nm) on the photodetection properties are evaluated under illumination using light emitting diodes (LEDs) and a laser. The photodetectors fabricated are successfully tested under different wavelengths, power densities and applied voltage and their photoresponse cyclic stability for each wavelength of illumination was recorded. From the sensitivity calculations, the sample with 20 nm Cu thickness (CAS 20) showed higher detection sensitivity for visible to near infrared wavelengths. Better responsivity results were obtained for CAS 40 because of its improved crystallinity and phase purity. Photodetector properties such as sensitivity and responsivity are evaluated for all the samples. These results are beneficial for cost effective and environment friendly photodetectors and optoelectronic devices based on CuSbS2 thin films.

Physical properties of inulin and inulin-orange juice: physical characterization and technological application.

In this work two systems based on a carbohydrate polymer were studied: inulin as model system and inulin-orange juice as complex system. Both system were stored at different water activity conditions and subsequently characterized. Water adsorption isotherms type II were fitted by the GAB model and the water monolayer content was determined for each system. From thermal analyzes it was found that at low water activities (aw) systems were fully amorphous. As aw increased, crystallinity was developed. This behavior was corroborated by X-ray diffraction. In the inulin-orange juice system, crystallization appears at lower water activity caused by the intensification of the chemical interaction of the low molecular weight species contained in orange juice. Glass transition temperature (Tg), determined by modulated differential scanning calorimeter, decreased with aw. As water is adsorbed, the physical appearance of samples changed which could be observed by optical microscopy and effectively related with the microstructure found by scanning electron microscopy.

[Splenic abscess: a case report and review of the literature]. / Absceso esplénico: presentación de un caso y revisión de la literatura.

A patients with multiple splenic abscesses of fungal origin ist presented. It is a unusual pathology that generally, only by postmortem ist diagnosed. The etiology, clinical features, diagnostic methods and therapeutic measures are discussed, and the necessity of early and accurate diagnostic and treatment. The prognosis of the splenic abscess is still associated with a high mortality.

[Beta-endorphin in acute focal cerebral infarct]. / Betaendorfina en el infarto cerebral focal agudo.

Experimental studies in animal models suggest that the endorphin system may be implicated in the pathogenetic mechanism of cerebral ischemic lesions. Naloxone has been shown to possess a beneficial effect on the neurologic deficit associated with cerebral ischemia in animal experiments, probably because of its endorphin antagonist properties. By contrast, the results of clinical trials are contradictory. Moreover, the true significance of high plasma levels of beta-endorphin in patients with acute focal cerebral infarct (AFCI) has not yet been elucidated. We have evaluated 23 patients with established AFCI, in whom plasma levels of beta-endorphin and corticotropin (ACTH) were simultaneously measured during the first 48 hours after the onset of the disease. The results were compared with those from a control group. In a subgroup of 9 cases new measurements were made after 7 days. In the patients with AFCI, significantly lower levels of beta-endorphin and ACTH than in the control group were found. One week later, a moderate nonsignificant increase in the plasma level of beta-endorphin was found. The localization and estimated size of the infarct area were not relevant. Probably, the plasma levels of beta-endorphin will need to be considered before naloxone therapy is indicated, and only if it is confirmed that the plasma levels of beta-endorphin reflect changes at the cerebral level, as the pathophysiological role of these opioids in AFCI has not yet been established.