18 research outputs found
Эффективность комбинированных аспирационных пункций при помощи тонкой иглы 20G и 21G в злокачественных скиррозных опухолях молочной железы
No full textEfficacy of combined fine needle aspiration with 21 and 20 Gauge în malignant tumors with squirrel pattern.Cancerul glandei mamare este situat pe primul loc în structura morbidităţii oncologice la femei (50,5%000) cu o incidență în continuă creștere în ultimii ani atît în Republica Moldova cît și la nivel global. Tumorile maligne cu pattern schiros reprezintă o problemă atât pentru medicul mamolog clinician cât și pentru medicul citolog luând în considerație particularitățile structurale ale acestor tipuri de tumori caracterizate prin densitate tisulară crescută și rigiditate marcată, corelate cu dificultăți tehnice de confirmare citologică. Aceasta a servit drept imbold pentru realizarea unui studiu prin care ne-am propus efectuarea unei analize comparative a puncțiilor aspiratorii cu ac fin 21 și 20 Gauge și citologiilor obținute la 139 paciente cu cancer mamar confirmat. Examinarea citologică la fiecare pacientă în parte a fost apreciată prin stabilirea comparativă a caracteristicelor „calitative” a materialului din aceeași tumoare cu ac fin calibru 21G și 20G.Эффективность комбинированных аспирационных пункций при помощи тонкой иглы 20G и 21G в злокачественных скиррозных опухолях молочной желез
Unique water-water coordination tailored by a metal surface
No full textAt low coverage of water on Cu(110), substrate-mediated electrostatics lead to zigzagging chains along [001] as observed with STM [T. Yamada, S. Tamamori, H. Okuyama, and T. Aruga, “Anisotropic water chain growth on Cu(110) observed with scanning tunneling microscopy” Phys. Rev. Lett. 96, 036105 (2006)]. Using x-ray absorption spectroscopy we find an anomalous low-energy resonance at ~533.1 eV which, based on density functional theory spectrum simulations, we assign to an unexpected configuration of water units whose uncoordinated O-H bonds directly face those of their neighbors; this interaction repeats over trough sites with enhanced electron density and is analogous to the case of a hydrated electron
Chemical bonding of water to metal surfaces studied with core-level spectroscopies
No full textThe nature of the contact layer of water on surfaces is of relevance for many practical fields, including corrosion, electrochemistry, environmental science and heterogeneous catalysis. Here we focus on the geometric and electronic structure of the water contact layer on transition metal surfaces and the interaction between the water monolayer and the surface. By combining synchrotron radiation-based X-ray photoelectron spectroscopy (XPS). X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) techniques with density functional theory (DFT) computational methods we obtain element-specific information on the partial local density of states, local atomic structure, geometrical parameters and molecular orientation, allowing general principles for water-metal interaction to be derived
ChemInform Abstract: Chemical Bonding of Water to Metal Surfaces Studied with Core-Level Spectroscopies
No full textLithium-7 nuclear magnetic resonance and Ti K-edge X-ray absorption spectroscopic investigation of electrochemical lithium insertion in Li4/3+xTi5/3O4
No full textThe spinel compound Li 4/3+xTi 5/3O 4 is known to undergo reversible lithium intercalation up to x=1 with almost no change in lattice parameters, hence its designation as a "zero strain" intercalation compound. Structural changes that accompany electrochemical Li intercalation into this compound were studied by both 7Li nuclear magnetic resonance (NMR) and Ti K-edge X-ray absorption fine structure (XAFS). The NMR results demonstrate that Li occupancies do not follow a simple distribution between two possible sites, one tetrahedral and one octahedral. The presence of at least one additional octahedral site is suggested. Line width measurements show that the Li + ions do not return to their original distribution after cycling. XAFS results indicate the presence of modest static disorder in Ti-O and Ti-Ti distances above x = 0.5. Both methods thus reveal subtle structural details previously unobserved by X-ray diffraction (XRD)
The role of substrate electrons in the wetting of a metal surface
No full textWe address how the electronic and geometric structures of metal surfaces determine water-metal bonding by affecting the balance between Pauli repulsion and electrostatic attraction. We show how the rigid d-electrons and the softer s-electrons utilize different mechanisms for the redistribution of charge that enables surface wetting. On open d-shell Pt(111), the ligand field of water alters the distribution of metal d-electrons to reduce the repulsion. The closed-shell Cu d(10) configuration of isostructural Cu(111), however, does not afford this mechanism, resulting in a hydrophobic surface and three-dimensional ice cluster formation. On the geometrically corrugated Cu(110) surface, however, charge depletion involving the mobile sp-electrons at atomic rows reduces the exchange repulsion sufficiently such that formation of a two-dimensional wetting layer is still favored in spite of the d(10) electronic configuration
O endividamento externo de Portugal no período 2000-2011.
No full textTCC (graduação)- Universidade Federal de Santa Catarina,Centro Sócio-Econômico, Curso de Ciências Econômicas.A Europa está vivendo uma grande crise no período 2008-09/2011-12. Portugal que faz parte da União Europeia e adotou o euro como moeda nacional sofre as consequencias desta crise e vê a sua situação econômica piorar. No presente trabalho, após uma apresentação do contexto geral no qual está inserido Portugal, centra-se o foco sobre o endividamento deste país. Pretende-se mostrar em que e por que o endividamento externo que era alto antes do ano 2000 (ano de ingresso de Portugal na Zona Euro), tornou-se crítico com o estourar da crise de 200809 e o desenrolar de suas consequencias em 2011-12. Mais precisamente ainda: pretende-se responder por que o endividamento externo quintuplicou-se no período 2000-2011. Mostra-se também que o aspecto externo deste país reflete-se internamente na sua economia. Prova disto são os níveis insustentáveis que os principais indicadores de contas nacionais atingiram
Intra- to Intermolecular Singlet Fission
No full textSinglet fission, the splitting
of one singlet into two triplets,
can potentially increase the efficiency of optoelectronic devices
beyond conventional limits. Among the singlet fission molecules discovered
to date, two mechanisms have emerged: intra- or intermolecular singlet
fission. Here we show a combined intra- to intermolecular singlet
fission mechanism in the model system of diphenyl-dicyano-oligoene
(DPDC). Excitation of DPDC to the first optically bright state leads
to the ultrafast formation of an intramolecular triplet pair, which
decays in 40 ps in the solution phase but can also split competitively
in 30 ps into two long-lived triplets (2×T<sub>1</sub>) on adjacent
molecules in solid films. These findings suggest a design principle
for efficient singlet fission: the independent tuning of singlet–triplet
pair coupling and triplet pair splitting from intra- and intermolecular
interactions, respectively
Structure and bonding of the water-hydroxyl mixed phase on Pt(111)
No full textWe combine low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and Auger electron spectroscopy (AES) with density functional theory (DFT) to reveal the structure and bonding of water-hydroxyl mixed layers adsorbed on Pt(111). We find that the stable water-hydroxyl adlayer forms a mixed phase of nearly coplanar hexamer structures resulting in (root 3 x root 3)R30 degrees and (3 x 3) unit cells, respectively. In the asymmetric (3 x 3) structure the lateral O-O distances alternate between long and short bond lengths similar to the chemical bonding network for OH- ions in solution. The chemical driving force behind this similarity is discussed in a molecular orbital picture
