3,289 research outputs found
Cs<sub>10</sub>Tl<sub>6</sub>SiO<sub>4</sub>, Cs<sub>10</sub>Tl<sub>6</sub>GeO<sub>4</sub>, and Cs<sub>10</sub>Tl<sub>6</sub>SnO<sub>3</sub> - First Oxotetrelate Thallides, Double Salts Containing "Hypoelectronic" [Tl<sub>6</sub>]<sup>6-</sup> Clusters
No full textCs(10)Tl(6)TtO(4) (Tt = Si, Ge) and Cs(10)Tl(6)SnO(3) were synthesized by the reaction of appropriate starting materials at 623-673 K, followed by fast cooling or quenching to room temperature, in arc-welded tantalum ampoules. According to single-crystal X-ray analyses, the compounds crystallize in new structure types (Cs(10)Tl(6)TtO(4) (Tt = Si, Ge), P2(1)/c and Cs(10)Tl(6)SnO(3), Pnma), consisting of [Tl(6)](6) clusters, which can be characterized as distorted octahedra compressed along one of the fourfold axes of an originally unperturbed octahedron, and [SiO(4)](4), [GeO(4)](4) or [SnO(3)](4) anions. The oxotetrelate thallides can be regarded as "double salts", which consist of Cs(6)Tl(6) on one side and respective oxosilicates, -germanates and -stannates on the other, showing almost not any direct interaction between the two anionic moieties, as might be expressed e. g. by the formula [Cs(6)Tl(6)][Cs(4)SiO(4)]. In contrast to the silicon and germanium compounds, where the oxidation state of the tetrel atom is unambiguously 4+, for the threefold coordinated tin atom in Cs(10)Tl(6)SnO(3) an oxidation state of 2+ has to be assumed. Thus, the latter reveal further evidence that the so called "hypoelectronic" [Tl(6)](6) cluster does not require additional electrons and is intrinsically stable. The distortion of [Tl(6)](6) can be understood in terms of the Jahn-Teller theorem. According to magnetic measurements all title compounds are diamagnetic
Tangle-bearing neurons survive despite disruption of membrane integrity in a mouse model of tauopathy
No full textNeurofibrillary tangles (NFTs) are associated with neuronal loss and correlate with cognitive impairment in Alzheimer disease, but how NFTs relate to neuronal death is not clear. We studied cell death in Tg4510 mice that reversibly express P301L mutant human tau and accumulate NFTs using in vivo multiphoton imaging of neurofibrillary pathology, propidium iodide (PI) incorporation into cells, caspase activation, and DNA labeling. We first observed that in live mice, a minority of neurons were labeled with the caspase probe or with PI fluorescence. These markers of cell stress were localized in the same cells and appeared specifically within NFT-bearing neurons. Contrary to expectations, the PI-stained neurons did not die during a day of observation; the presence of Hoechst-positive nuclei in them on the subsequent day indicated that the NFT-associated membrane disruption, as suggested by PI staining, and caspase activation do not lead to immediate death of neurons in this tauopathy model. This unique combination of in vivo multiphoton imaging with markers of cell death and pathological alteration is a powerful tool for investigating neuronal damage associated with neurofibrillary pathology
Improving cardiovascular and renal outcomes in gout: what should we target?
No full textEpidemiological and experimental studies have shown that hyperuricaemia and gout are intricately linked with hypertension, metabolic syndrome, chronic kidney disease and cardiovascular disease. A number of studies suggest that hyperuricaemia and gout are independent risk factors for the development of these conditions and that these conditions account, in part, for the increased mortality rate of patients with gout. In this Review, we first discuss the links between hyperuricaemia, gout and these comorbidities, and present the mechanisms by which uric acid production and gout might favour the development of cardiovascular and renal diseases. We then emphasize the potential benefit of urate-lowering therapies on cardiovascular and renal outcomes in patients with hyperuricaemia. The mechanisms that link elevated serum uric acid levels and gout with these comorbidities seem to be multifactorial, implicating low-grade systemic inflammation and xanthine oxidase (XO) activity, as well as the deleterious effects of hyperuricaemia itself. Patients with asymptomatic hyperuricaemia should be treated by nonpharmacological means to lower their SUA levels. In patients with gout, long-term pharmacological inhibition of XO is a treatment strategy that might also reduce cardiovascular and renal comorbidities, because of its dual effect of lowering SUA levels as well as reducing free-radical production during uric acid formation
The charge transfer and ion formation in liquid Li-Tl alloys
No full textThe 7Li NMR Knight shift, K, and the spin-lattice relaxation time, T1, were measured for liquid Li–Tl alloys. The K decreases rapidly with the addition of Tl up to 20 at.% Tl. In the concentration from 20 to 50 at.% Tl, the K decreases only slightly and the K of 50 at.% Tl is 60% of K for the pure liquid Li. Such a decrease of K is considered as an indication for the strong charge transfer from Li to Tl. These tendencies are similar to those from previous studies for liquid Li–Ga and Li–In alloys. However, beyond 50 at.% Tl, the K increases and reaches to an almost constant value (70% of K for the pure liquid Li). Such a back donation of charge is absent for liquid Li–Ga and Li–In alloys. It is considered that the tendency of the formation of ionic structural unit for liquid Li–Tl alloys is slightly weaker compared with the cases of liquid Li–Ga and Li–In alloys. The T1 is also discussed with the relation to the Knight shift and the electronic properties
THE VISIBLE EMISSION SPECTRA OF Zn , Cd , Zn Tl, AND Cd Tl MOLECULES
No full textAuthor Institution: Department of Physics, Indian Institute of Technology; Department of Physics, State University of New York at BuffaloNew Spectra have been obtained for Zn-Tl and Cd-Tl mixtures excited by a high frequency oscillator and studied under a dispersion of 5\AA/mm. Both the mixtures show one system in the red, one in the blue and continuous bands attached to the Tl lines 3775 and 5350 \AA. The red system of Zn-Tl mixture exhibits an isotope effect, which shows Zn as the emitter. The emitter for the red system of Cd-Tl mixture is Cd . The blue systems and continuous bands are due to diatomic ZnTl and CdTl molecules. A vibrational analysis of all these systems, wherever possible has been carried out and the constants determined
Ceramic Tl-oxide based superconductors reinvestigated by magnetic separation technique and SQUID measurements
No full textCeramic samples of Tl(2)Ba(2)Ca(2)Cu(3)O(10) (Tl-2223) and TlBa(2)Ca(2)Cu(3)O(9) (Tl-1223) superconductor were resynthesized by using several preparation procedures and investigated by means of magnetic separation technique, allowing evaluation of the superconducting critical temperature of individual grains as small as 25 mu m. Although an onset of diamagnetism detected by SQUID measurements was observed around 130 K in Tl-2223 and 134 K in Tl-1223, no grains with T(c) > 125 K were found for Tl-2223 and with T(c) > 130 K for Tl-1223. Furthermore, the volume fraction of superconductivity of such ceramics was less than 5% and 3% in best samples of Tl-2223 and Tl-1223, respectively. Here we provide a detailed comparison of results obtained by magnetic separation technique with those by SQUID applied to individual grains and bulk samples. (C) 2011 Elsevier Masson SAS. All rights reserved
Regular [Tl<sub>6</sub>]<sup>6-</sup> Cluster in Cs<sub>4</sub>Tl<sub>2</sub>O Exhibiting Closed-Shell Configuration and Energetic Stabilization due to Relativistic Spin-Orbit Coupling
No full textCs(4)Tl(2)O was synthesized by reaction of the binary compounds CsTl and Cs(2)O at 573 K, followed by slow cooling to room temperature. According to single-crystal X-ray analysis, the title compound crystallizes in a new structure type (trigonal, space group R (3) over barm (no. 166), a = 11.986(1), c = 20.370(2) angstrom, Z = 9). It consists of isolated [Tl(6)](6-) octahedra, being regular with respect to the equality of all three main diagonals (4.546(5) angstrom), and of [Cs(12)O(3)](6+) triple octahedra extending along the c direction. The electronic structure of Cs(4)Tl(2)O was examined by relativistic density functional calculations including spin-orbit coupling and compared to the one of Rb(10)Tl(6)O(2), which exhibits a highly distorted [Tl(6)](6-) octahedra. In the latter case the closed-shell electronic structure is the result of a Jahn-Teller distortion. In contrast, the regular one in Cs(4)Tl(2)O corresponds to a closed-shell configuration, in accordance with diamagnetic properties, only if spin-orbit coupling is considered
TL and OSL properties of beta irradiated Y2O3 nanocrystal
No full textNanocrystalline yttrium oxide (Y2O3) is synthesized by low temperature sol-gel technique and synthesized material is annealed at 900°C. The annealed β-rayed Y2O3 two TL glows with prominent peak at 407 K and weak glow peak at 643 K were observed in all irradiated samples. It is found that TL glow peaks intensity linearly increases with increase in β-dose from 0.813 - 40.625 Gy. The TL kinetic parameters are calculated using glow curve deconvoluted (GCD) method. The TL glows exhibits general order kinetics. Intense optical stimulated luminescence (OSL) is observed in the Y2O3 sample. These material exhibits linearity and reproducibility and hence, it suggests that this material may be used as dosimetric applications. © 2017 Author(s)
Preparation of (R)-2-chloro-1-(m-chlorophenyl)ethanol by Lipozyme TL IM-catalyzed second resolution
No full text(R)-2-Chloro-1-(m-chlorophenyl)ethanol, a precursor of (R)-3-chlorostyrene oxide which is the key chiral intermediate for the preparation of several beta 3-adrenergic receptor agonists was prepared in 40% yield and 99% ee by the Lipozyme TL IM-catalyzed second resolution of the corresponding racemate in the presence of vinyl acetate. (C) 2012 Shi Wen Xia. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved
A<sub>10</sub>Tl<sub>6</sub>O<sub>2</sub> (A = K, Rb) cluster compounds combining structural features of thallium cluster anions and of alkali metal sub-oxides
No full textNew alkali metal thallideoxides, A(10)Tl(6)O(2) (A = K, Rb), crystallize in a unique structure consisting of hypoelectronic [Tl-6](6-) clusters in the shape of compressed octahedra, together with oxygen-centred alkali metal octahedra that have been identified as constitutive of alkali metal sub-oxides
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