University of Cagliari

About: University of Cagliari is a education organization based out in Cagliari, Italy. It is known for research contribution in the topics: Population & Dopamine. The organization has 11029 authors who have published 29046 publications receiving 771023 citations. The organization is also known as: Università degli Studi di Cagliari & Universita degli Studi di Cagliari.

The link between thyroid autoimmunity (antithyroid peroxidase autoantibodies) with anxiety and mood disorders in the community: a field of interest for public health in the future

Abstract: To evaluate the association between mood and anxiety disorders and thyroid autoimmunity in a community sample. Methods: A community based sample of 222 subjects was examined. Psychiatric diagnoses were formulated using the International Composite Diagnostic Interview Simplified (CIDIS), according to DSM-IV criteria. All subjects underwent a complete thyroid evaluation including physical examination, thyroid echography and measure of serum free T4 (FT4), free T3 (FT3), thyroid-stimulating hormone (TSH) and anti-thyroid peroxidase autoantibodies (anti-TPO). 16.6% of the overall sample had an anti-TPO value above the normal cut-off. Subjects with at least one diagnosis of anxiety disorders (OR = 4.2, C.L. 95% 1.9–38.8) or mood disorders (OR = 2.9, Cl 95% 1.4–6.6, P < 0.011) were positive for serum anti-TPO more frequently than subjects without mood or anxiety disorders. A statistically significant association with anti-TPO+ was found in Anxiety Disorder Not Otherwise Specified (OR = 4.0, CL 95% 1.1–15.5), in Major Depressive Episode (OR = 2.7, CL 95% 1.1–6.7) and Depressive Disorder Not Otherwise Specified (OR = 4.4, S CL 95% 1–19.3). The study seems to suggest that individuals in the community with thyroid autoimmunity may be at high risk for mood and anxiety disorders. The psychiatric disorders and the autoimmune reaction seem to be rooted in a same (and not easy correctable) aberrancy in the immuno-endocrine system. Should our results be confirmed, the findings may be of great interest for future preventive and case finding projects.

Visible-light photocurrent response of TiO2–polyheptazine hybrids: evidence for interfacial charge-transfer absorption

Abstract: We investigated photoelectrodes based on TiO2–polyheptazine hybrid materials. Since both TiO2 and polyheptazine are extremely chemically stable, these materials are highly promising candidates for fabrication of photoanodes for water photooxidation. The properties of the hybrids were experimentally determined by a careful analysis of optical absorption spectra, luminescence properties and photoelectrochemical measurements, and corroborated by quantum chemical calculations. We provide for the first time clear experimental evidence for the formation of an interfacial charge-transfer complex between polyheptazine (donor) and TiO2 (acceptor), which is responsible for a significant red shift of absorption and photocurrent response of the hybrid as compared to both of the single components. The direct optical charge transfer from the HOMO of polyheptazine to the conduction band edge of TiO2 gives rise to an absorption band centered at 2.3 eV (540 nm). The estimated potential of photogenerated holes (+1.7 V vs.NHE, pH 7) allows for photooxidation of water (+0.82 V vs.NHE, pH 7) as evidenced by visible light-driven (λ > 420 nm) evolution of dioxygen on hybrid electrodes modified with IrO2 nanoparticles as a co-catalyst. The quantum-chemical simulations demonstrate that the TiO2–polyheptazine interface is a complex and flexible system energetically favorable for proton-transfer processes required for water oxidation. Apart from water splitting, this type of hybrid materials may also find further applications in a broader research area of solar energy conversion and photo-responsive devices.

Surfactant effect of gallium during molecular-beam epitaxy of GaN on AlN (0001)

Abstract: We study the adsorption of Ga on ~0001! GaN surfaces by reflection high-energy electron diffraction. It is shown that a dynamically stable Ga bilayer can be formed on the GaN surface for appropriate Ga fluxes and substrate temperatures. The influence of the presence of this Ga film on the growth mode of GaN on AlN~0001! by plasma-assisted molecular-beam epitaxy is studied. It is demonstrated that under nearly stoichiometric and N-rich conditions, the GaN layer relaxes elastically during the first stages of epitaxy. At high temperatures the growth follows a Stranski-Krastanov mode, whereas at lower temperatures kinetically formed flat platelets are observed. Under Ga-rich conditions—where a Ga bilayer is rapidly formed due to excess Ga accumulating on the surface—the growth follows a Frank-van der Merwe layer-by-layer mode at any growth temperature and no initial elastic relaxation occurs. Hence, it is concluded that excess Ga acts as a surfactant, effectively suppressing both Stranski-Krastanov islanding and platelet formation. It is further demonstrated that the StranskiKrastanov transition is in competition with elastic relaxation by platelets, and it is only observed when relaxation by platelets is inefficient. As a result, a growth mode phase diagram is outlined for the growth of GaN on AlN~0001!.