11,872 research outputs found

    Initial pseudo-steady state & asymptotic KPZ universality in semiconductor on polymer deposition

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    The Kardar-Parisi-Zhang (KPZ) class is a paradigmatic example of universality in nonequilibrium phenomena, but clear experimental evidences of asymptotic 2D-KPZ statistics are still very rare, and far less understanding stems from its short-time behavior. We tackle such issues by analyzing surface fluctuations of CdTe films deposited on polymeric substrates, based on a huge spatio-temporal surface sampling acquired through atomic force microscopy. A \textit{pseudo}-steady state (where average surface roughness and spatial correlations stay constant in time) is observed at initial times, persisting up to deposition of 104\sim 10^{4} monolayers. This state results from a fine balance between roughening and smoothening, as supported by a phenomenological growth model. KPZ statistics arises at long times, thoroughly verified by universal exponents, spatial covariance and several distributions. Recent theoretical generalizations of the Family-Vicsek scaling and the emergence of log-normal distributions during interface growth are experimentally confirmed. These results confirm that high vacuum vapor deposition of CdTe constitutes a genuine 2D-KPZ system, and expand our knowledge about possible substrate-induced short-time behaviors.Comment: 13 pages, 8 figures, 2 table

    Kounis Syndrome Associated With Selective Anaphylaxis to Cefazolin.

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    Temperature effect on (2+1) experimental Kardar-Parisi-Zhang growth

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    We report on the effect of substrate temperature (T) on both local structure and long-wavelength fluctuations of polycrystalline CdTe thin films deposited on Si(001). A strong T-dependent mound evolution is observed and explained in terms of the energy barrier to inter-grain diffusion at grain boundaries, as corroborated by Monte Carlo simulations. This leads to transitions from uncorrelated growth to a crossover from random-to-correlated growth and transient anomalous scaling as T increases. Due to these finite-time effects, we were not able to determine the universality class of the system through the critical exponents. Nevertheless, we demonstrate that this can be circumvented by analyzing height, roughness and maximal height distributions, which allow us to prove that CdTe grows asymptotically according to the Kardar-Parisi-Zhang (KPZ) equation in a broad range of T. More important, one finds positive (negative) velocity excess in the growth at low (high) T, indicating that it is possible to control the KPZ non-linearity by adjusting the temperature.Comment: 6 pages, 5 figure

    Colloidal CuFeS2 Nanocrystals: Intermediate Fe d-Band Leads to High Photothermal Conversion Efficiency

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    We describe the colloidal hot-injection synthesis of phase-pure nanocrystals (NCs) of a highly abundant mineral, chalcopyrite (CuFeS2). Absorption bands centered at around 480 and 950 nm, spanning almost the entire visible and near infrared regions, encompass their optical extinction characteristics. These peaks are ascribable to electronic transitions from the valence band (VB) to the empty intermediate band (IB), located in the fundamental gap and mainly composed of Fe 3d orbitals. Laser-irradiation (at 808 nm) of an aqueous suspension of CuFeS2 NCs exhibited significant heating, with a photothermal conversion efficiency of 49%. Such efficient heating is ascribable to the carrier relaxation within the broad IB band (owing to the indirect VB-IB gap), as corroborated by transient absorption measurements. The intense absorption and high photothermal transduction efficiency (PTE) of these NCs in the so-called biological window (650-900 nm) makes them suitable for photothermal therapy as demonstrated by tumor cell annihilation upon laser irradiation. The otherwise harmless nature of these NCs in dark conditions was confirmed by in vitro toxicity tests on two different cell lines. The presence of the deep Fe levels constituting the IB is the origin of such enhanced PTE, which can be used to design other high performing NC photothermal agents.Comment: 12 pages, Chemistry of Materials, 31-May-201

    Reflectance spectrometry of rocks from the comstock lode (Virginia City, Nevada, USA) and its comparison with X-ray diffraction

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    This paper presents the results of mineralogical analysis of hydrothermal altered rocks from the Comstock Lode, near Virginia City, Nevada, USA, using two different techniques: reflectance spectrometry and X-ray diffraction. These results are discussed based on their quickness, accuracy and low costs. The applicability to mineral mapping using high spectral resolution remote sensing images is also briefly discussed. Comparison of the results obtained for both techniques have a good degree of correlation, showing that reflectance spectrometry represents an expedite, simple and relatively inexpensive technique, capable of mapping numerous minerals in the field or in laboratory.Este trabalho apresenta resultados de análises mineralógicas de rochas com alteração hidrotermal do Lode de Comstock, próximo a Virgínia City, Estado de Nevada, EUA, utilizando duas diferentes técnicas: espectrometria de reflexão e difração de raio-X. Os resultados são discutidos em função de sua rapidez e facilidade de obtenção e acuracidade. Discute-se ainda, brevemente, sua aplicabilidade ao mapeamento mineral utilizando imagens de sensoriamento remoto com alta resolução espectral. A título de ilustração, apresenta-se uma imagem TM-Landsat da região de estudo, na qual pode-se observar a característica resposta das áreas alteradas hidrotermalmente. A comparação dos resultados obtidos com as duas técnicas apresentou um razoável grau de correlação, mostrando que a espectrometria é uma ferramenta expedita, simples, relativamente barata e capaz de identificar no campo ou em laboratório minerais de interesse na prospecção de áreas com alteração hidrotermal

    Potato production impacts of the association trichodorids and TRV in naturally infected fields

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    An investigation was conducted to determine the effect of soil-born Tobacco rattle virus (TRV) isolates on yield and some quality attributes of 8 potato cultivars (Agata, Amorosa, Almera, Cunéria, Kondor, Picasso, Raja and Stemster) in Portuguese growing areas. Preliminary results revealed that some attributes (canopy growth, total yield, tuber numbers and yield within size grades, tuber spraing symptoms and secondary growths) are severely affected in the sites with viruliferous trichodorids transmitting TRV. It was shown that TRV has real conditions for survival and cause economic impact in potato crop in these regions. These results have potential interest to all potato growing countries.Centro de Biologia Molecular e Ambiental (CBMA), UMCentre of Natural Resources, Environment and Society Studies (CERNAS), College of Agriculture of Coimbra (ESAC)Eurobatata, Comércio de Produtos Alimentares, Lda, PORTUGA

    Knowledge and attitude towards the gradual reduction of salt in bread – an online survey

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    Aim: Assess knowledge and attitude towards the gradual reduction of salt in bread and the potential impact on eating habits of children (6-18 years) and their families, as part as a Health Impact Assessment pilot study.N/

    Thermal matter and radiation in a gravitational field

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    We study the one-loop contributions of matter and radiation to the gravitational polarization tensor at finite temperatures. Using the analytically continued imaginary-time formalism, the contribution of matter is explicitly given to next-to-leading (T2T^2) order. We obtain an exact form for the contribution of radiation fields, expressed in terms of generalized Riemann zeta functions. A general expression is derived for the physical polarization tensor, which is independent of the parametrization of graviton fields. We investigate the effective thermal masses associated with the normal modes of the corresponding graviton self-energy.Comment: 32 pages, IFUSP/P-107

    P09-15. Selection of higher avidity HLA-restricted T cell responses as a viral adaptation strategy

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    Loss of immune reactivity due to HIV mutational escape is well described. Data generated from a large population-based study (n>800) suggested that certain CD8 T cell epitopes are created as a result of HIV adaptation and are associated with enhanced viral replication. Here we sought to investigate the HLA-restricted T-cell responses associated with seven such adaptations
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