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- Author or Editor: A. Benedetti x
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Abstract
The thermal behavior of Cu—Al alloys with 17, 19 and 21 at.%Al was examined by differential thermal analysis (DTA), differential scanning calorimetry (DSC), X-ray diffractometry (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). The presence of the gamma phase (Al4Cu9)was clearly detected for the Cu—19 at.%Al alloy and caused the 
2 phase disordering process in two stages. The tendency to increase the
2 dissolution precipitates with the increase in the Al content seems to be reverted for compositions at about 21 at.%Al and the heating/cooling ratio seems to influence the thermal response of this process. The presence of the endothermic peak corresponding to the 
1
transformation depends on an incomplete decomposition reaction. The variation of the heating rate showed that the
1
(+
1) decomposition is the dominant reaction for alloys containing 19 and 21 at.%Al.
The processes of crystallization of fibres (diameter 10–15μm) and coarse powders (grain size 500–1000μm) with four compositions in the system SiO2-Li2O-TiO2-Al2O3 were studied by conventional and in situ high-temperature XRD, DTA, SEM and optical microscopy. Activation energies of crystallization and morphological indices were deduced from the kinetic curves obtained by recording the high-temperature XRD peak intensity as a function of time. The glass-ceramic fibres drawn from compositions which exhibit glass-inglass phase separation show prevailing not-oriented bulk crystallization, whereas prevailing surface crystallization was found for single-phase glass fibres. Homogeneously-dispersed crystallization was obtained on heating fibres of these compositions. The partially cocrystallized glass fibres of eutectic composition between Li-metasilicate andβ-spodumene gave rise to a very fine and homogeneously-dispersed sub-microstructure.
Abstract
Thermogravimetry, cyclic voltammetry and other analytical techniques were used to study the reactions of mercury with pure iridium. The results allowed to suggest when subjected to heat or anodic stripping voltammetry an electrodeposited mercury film reacts with Ir substrate and at least three mass loss steps and three peaks appear in the mercury desorption process. The first two were attributed to Hg(0)species removal like a mercury bulk and a mercury monolayer. The last can be ascribed to the mercury removal from a solid solution with iridium.
Abstract
Thermogravimetry (TG) and other analysis techniques (EDX, SEM, Mapping surface, X-ray diffraction, inductively coupled argon plasma emission spectroscopy and atomic spectrometry with cold vapor generation) were used to study the reaction of Hg with Rh. The results permitted the suggestion that, when subjected to heat, an electrodeposited Hg film reacts with Rh to form intermetallic products with different stabilities, as indicated by at least three mass loss steps. In the first step, between room temperature and 160C, only the bulk Hg is removed. From this temperature up to about 175C, the mass loss can be attributed to the desorption of a film of metallic Hg. The last step, from 175 to 240C, can be ascribed to the removal of Hg from a thin dark film of RhHg2 .
Solid state reactions in the platinum–mercury system
Thermogravimetry and differential scanning calorimetry
Abstract
Thermogravimetry, Differential Scanning Calorimetry and other analytical techniques (Energy Dispersive X-ray Analysis; Scanning Electron Microscopy; Mapping Surface; X-ray Diffraction; Inductively Coupled Plasma Atomic Emission Spectroscopy and Cold Vapor Generation Atomic Absorption Spectroscopy) have been used to study the reaction of mercury with platinum foils. The results suggest that, when heated, the electrodeposited Hg film reacts with Pt to form intermetallic compounds each having a different stability, indicated by at least three mass loss steps. Intermetallic compounds such as PtHg4, PtHg and PtHg2 were characterized by XRD. These intermetallic compounds were the main products formed on the surface of the samples after partial removal of bulk mercury via thermal desorption. The Pt(Hg) solid solution formation caused great surface instability, attributed to the atomic size factor between Hg and Pt, facilitating the acid solution’s attack to the surface.
Abstract
Thermogravimetry (TG), cyclic voltammetry (CV) and other analytical techniques were used to study the reactions of mercury with Pt–30% Ir alloy. The results allowed to suggest that an electrodeposited mercury film interacts with the substrate and when subjected to heat or electrochemical removal at least four mass loss steps or five peaks appeared during the mercury desorption process. The first two steps were attributed to Hg(0) removal probably from the bulk and from the adsorbed monolayer which wets the electrode surface. These two processes are responsible for peaks D and F in the cyclic voltammograms. The last two peaks (G, H) in CV were ascribed to the intermetallic compound decomposition. In TG curves, the last two steps were attributed to the PtHg4 (third step), and PtHg2 decomposition followed by Hg removal from the subsurface. The PtHg2 was formed by an eutectoide reaction: PtHg→PtHg2+Hg(Pt–Ir). The Hg diffused to the subsurface was not detectable by cyclic voltammetry.
11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) is a NADPH dependent oxidoreductase of the endoplasmic reticulum lumen which converts cortisone to cortisol and plays a role in the pathogenesis of metabolic syndrome and type 2 diabetes. The aim of our study was to investigate the correlation between the expression/activity of 11βHSD1 and obesity. Liver and adipose tissue microsomes of an obese (Zucker) and a non-obese (Goto-Kakizaki) type 2 diabetes model rat strains were used. 11βHSD1 expression was detected at mRNA, protein and activity level. The activity of 11βHSD1 was increased in the adipose tissue and decreased in the liver of the obese Zucker rat, while its mRNA levels were significantly different only in the adipose tissue. In diabetic Goto-Kakizaki rat both the expression and the activity of 11βHSD1 were elevated in liver, but not in adipose tissue. These results suggest that the prereceptorial glucocorticoid activation is different in the liver and adipose tissue of the two diabetes models. This phenomenon might be responsible for the obese and lean phenotypes in type 2 diabetes.
