Density functional study of Aun_n (n=2-20) clusters: lowest-energy structures and electronic properties

We have investigated the lowest-energy structures and electronic properties of the Au$_n$(n=2-20) clusters based on density functional theory (DFT) with local density approximation. The small Au$_n$ clusters adopt planar structures up to n=6. Tabular cage structures are preferred in the range of n=10-14 and a structural transition from tabular cage-like structure to compact near-spherical structure is found around n=15. The most stable configurations obtained for Au$_{13}$ and Au$_{19}$ clusters are amorphous instead of icosahedral or fcc-like, while the electronic density of states sensitively depend on the cluster geometry. Dramatic odd-even alternative behaviors are obtained in the relative stability, HOMO-LUMO gaps and ionization potentials of gold clusters. The size evolution of electronic properties is discussed and the theoretical ionization potentials of Au$_n$ clusters compare well with experiments.Comment: 6 pages, 7 figure

Serum B cell activating factor and interleukin 10 levels in common variable immunodeficiency: Relationship with clinical findings

© 2019 Inst. Sci. inf., Univ. Defence in Belgrade. All rights reserved. Background/Aim. Common variable immunodeficiency (CVID) is an immunologically and clinically heterogeneous disorder. Disturbed cytokine production is implicated in dysfunctional immune response. The aim of this study was to investigated B-cell activating factor (BAFF) and interleukin (IL)- 10 levels in CVID patients. Methods. The study included 28 CVID patients diagnosed and followed during a 20-year period (mean follow-up 14.5 years). Control groups consisted of 4 patients with X-linked agammaglobulinemia (XLA) and 21 healthy subjects. According to clinical characteristics, the CVID patients were divided into four groups which partly overlap: chronic pulmonary diseases (n = 21), splenomegaly (n = 13), autoimmune diseases (n = 9) and patients with recurrent infections despite regular intravenous immunoglobulin (IVIg) substitution (n = 4). The serum levels of BAFF and IL-10 were measured by commercial ELISA. Results. The BAFF levels were found to be higher in all CVID patients compared to the healthy controls (p < 0.01). The most significant differences were observed in the patients with pulmonary diseases and splenomegaly (p < 0.0001). Also, concentrations of IL-10 were higher in all CVID patients in comparison with the XLA patients (p < 0.05) and healthy subjects (p < 0.01). A statistically significant positive correlation (r = 0.86; p < 0.01) was found between the levels of BAFF and IL-10 in the CVID patients with autoimmune diseases. We demonstrated that the CVID patients with chronic pulmonary diseases had higher levels of IL-10, while the CVID patients with recurrent infections had higher BAFF concentrations in comparison to the patients without these features (p < 0.05). Conclusion. In spite of the limited number of patients, this is the first report from Serbia, examining the serum levels of BAFF and IL-10 in the CVID patients. Our study showed significantly increased concentrations of serum BAFF and IL-10 in the patients with CVID compared to the healthy subjects. Further studies are needed to confirm our findings that the BAFF levels are more pronounced in patients with recurrent infections while IL-10 levels are higher in patients with chronic pulmonary diseases