428 research outputs found

    Ga+, In+ and Tl+ Impurities in Alkali Halide Crystals: Distortion Trends

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    A computational study of the doping of alkali halide crystals (AX: A = Na, K; X = Cl, Br) by ns2 cations (Ga+, In+ and Tl+) is presented. Active clusters of increasing size (from 33 to 177 ions) are considered in order to deal with the large scale distortions induced by the substitutional impurities. Those clusters are embedded in accurate quantum environments representing the surrounding crystalline lattice. The convergence of the distortion results with the size of the active cluster is analyced for some selected impurity systems. The most important conclusion from this study is that distortions along the (100) and (110) crystallographic directions are not independent. Once a reliable cluster model is found, distortion trends as a function of impurity, alkali cation and halide anion are identified and discussed. These trends may be useful when analycing other cation impurities in similar host lattices.Comment: LaTeX file. 7 pages and 2 pictures. Accepted for publication in J. Chem. Phy

    Lattice Distortions Around a Tl+ Impurity in NaI:Tl+ and CsI:Tl+ Scintillators. An Ab Initio Study Involving Large Active Clusters

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    Ab initio Perturbed Ion cluster-in-the-lattice calculations of the impurity centers NaI:Tl+ and CsI:Tl+ are pressented. We study several active clusters of increasing complexity and show that the lattice relaxation around the Tl+ impurity implies the concerted movement of several shells of neighbors. The results also reveal the importance of considering a set of ions that can respond to the geometrical displacements of the inner shells by adapting selfconsistently their wave functions. Comparison with other calculations involving comparatively small active clusters serves to assert the significance of our conclusions. Contact with experiment is made by calculating absorption energies. These are in excellent agreement with the experimental data for the most realistic active clusters considered.Comment: 7 pages plus 6 postscript figures, LaTeX. Submmited to Phys, Rev.

    Ab Initio Calculation of the Lattice Distortions induced by Substitutional Ag- and Cu- Impurities in Alkali Halide Crystals

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    An ab initio study of the doping of alkali halide crystals (AX: A = Li, Na, K, Rb; X = F, Cl, Br, I) by ns2 anions (Ag- and Cu-) is presented. Large active clusters with 179 ions embedded in the surrounding crystalline lattice are considered in order to describe properly the lattice relaxation induced by the introduction of substitutional impurities. In all the cases considered, the lattice distortions imply the concerted movement of several shells of neighbors. The shell displacements are smaller for the smaller anion Cu-, as expected. The study of the family of rock-salt alkali halides (excepting CsF) allows us to extract trends that might be useful at a predictive level in the study of other impurity systems. Those trends are presented and discussed in terms of simple geometric arguments.Comment: LaTeX file. 8 pages, 3 EPS pictures. New version contains calculations of the energy of formation of the defects with model clusters of different size

    Headshaking associated with a unique presentation of guttural pouches infection and otitis media in a Quarter Horse stallion: diagnosis, medical treatment and outcome

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    : A 3-year-old Quarter Horse stallion was referred for headshaking (HS) syndrome of one month duration. The horse underwent complete HS workup. Physical examination revealed up-and-down head movements associated with nose snorting during lunging and riding, in the absence of other abnormalities at rest or in motion. Lameness, neurologic and behavioural evaluations were unremarkable. Endoscopic examination of the upper respiratory tract showed bilateral guttural pouches (GPs) inflammation. The mucosal surface was altered by the presence of areas of microbullous appearance coalescing into some bullae of larger diameter. A bacterial culture obtained by flushing, brushing and biopsy of the GP mucosa was positive for Serratia marcescens. Computed tomographic evaluation was indicative of: moderate bilateral GP inflammation, bilateral otitis media, and nuchal ligament enthesopathy, with uncertain significance. The horse was treated with antimicrobials according to the sensitivity test, systemic NSAIDs and rest. At the one-month follow-up, HS condition was improved and the endoscopic examination showed a limited number of bullous lesions remaining. Bacterial culture re-obtained from the GPs lavages was positive for Streptococcus equi zooepidemicus. Based on the residual evidence of GP infection, the horse was re-treated with antimicrobials according to the sensitivity test, systemic NSAIDs and rest. At the two-month follow-up, HS condition was considered resolved based on clinical evaluation, the horse resumed gradually training with satisfactory results. Endoscopy and bacteriology showed resolution of GP infection. At one-year follow-up no relapses were reported

    Editorial: Advances in Endocrinology: Stem Cells and Growth Factors

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    Stem Cells investigation in Endocrinology: leading stem cell scientists and developmental endocrinologists, critically review both cutting-edge approaches to stem cell biology and the application of stem cells and their secretome to translational/precision medicine, endocrine diseases, including diabetes, tissue/organ repairs, energy metabolism, and metabolic disorders

    Mesenchymal stem cells as promoters, enhancers, and playmakers of the translational regenerative medicine

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    Since their first isolation and characterization by Friedenstein et al. in 1974, mesenchymal stem cells (MSCs) were proven essential for tissue regeneration and homeostasis. Over the years, thanks to a better understanding of the molecular mechanisms underlying the therapeutic effects of MSCs, several approaches with MSC-based therapies have been proposed, in order to treat different human diseases. In this light, MSCs are currently being tested in preclinical in vivo settings as well as in early-stage clinical trials for their ability to modulate immune responses, fostering wound healing and tissue regeneration of various tissue types and organs, including the skin, bone, cartilage, brain, muscle, and tendons

    Phosphorylation of B14.5a subunit from bovine heart complex I identified by titanium dioxide selective enrichment and shotgun proteomics

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    Shotgun proteomics was used to study the steady phosphorylation state of NADH:ubiquinone oxidoreductase (complex I) subunits from bovine heart mitochondria. A total tryptic digestion of enzymatically active complex I was performed, and the resulting peptide mixture was subjected to phosphopeptide enrichment by the use of titanium dioxide (TiO2). The phosphopeptide-enriched fraction was separated and analyzed with nanoscale reverse-phase HPLC-ESI-MS/MS in single information-dependent acquisition. Hence two phosphorylated complex I subunits were detected: 42 kDa and B14.5a. Phosphorylation of 42-kDa subunit at Ser-59 has already been determined with fluorescent phosphoprotein-specific gel staining and mass spectrometry (Schilling, B., Aggeler, R., Schulenberg, B., Murray, J., Row, R. H., Capaldi, R. A., and Gibson, B. W. (2005) Mass spectrometric identification of novel phosphorylation site in subunit NDUFA10 of bovine mitochondrial complex I. FEBS Lett. 579, 2485-2490). In our work, this finding was confirmed using a non-gel-based approach. In addition, we report novel phosphorylation on B14.5a nuclear encoded subunit. We demonstrated evidence of the phosphorylation site at Ser-95 residue by collision-induced dissociation experiments on three different molecular ions of two tryptic phosphopeptides of B14.5a

    Experimental and Numerical Analysis of a FRCM Reinforced Parabolic Tuff Barrel Vault

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    An experimental and numerical analysis of the structural behaviour of a barrel tuff masonry vault strengthened by a Fiber Reinforced Cementitious Matrix (FRCM) reinforcement system it is proposed. The geometry and the materials of the vault are representative of some historical constructions in Apulia (Italy). The vault, under the action of the self-weight and of a distributed load representative of the infill, has been first damaged by differential settlement of abutments, and then repaired and strengthened by FRCM composites. Finally the structure has been subjected to a increasing concentrated load on the extrados. A 3D heterogeneous FE Abaqus numerical model describing the above mentioned experimental conditions is carried out in order to reproduce the response of the FRCM reinforced vault. The obtained experimental and numerical results allows for discussing the structural behaviour of the reinforced vault, and then the effectiveness of the employed reinforcement
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