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Search Results: 1 - 10 of 504970 matches for " Lia M. B.;Torre "
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EPR and magnetic studies of a carboxylate-bridged dinuclear copper(II) compound: [cu2(flu)4(dmf)2]
Nascimento, Otaciro R.;Napolitano, Lia M. B.;Torre, María H.;Pe?a, Octavio;Calvo, Rafael;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000400009
Abstract: we report magnetic and epr (electron paramagnetic resonance) spectroscopy studies of [cu2(flu)4(dmf)2] (flu = flufenamate and dmf = dimethylformamide), which has cuii ions in tetracarboxylate "paddle wheel" dinuclear units. susceptibility measurements at 10 < t < 275 k allowed the evaluation of an antiferromagnetic intradinuclear exchange coupling j0 = -294 ± 5 cm-1 between cuii ions (hex = "j0 s1·s2). epr experiments at 300 k in powder and single-crystals at 9.5 and 34.4 ghz indicated g// = 2.373, g⊥ = 2.073 and zero field splitting parameters d = (-0.334 ± 0.001) cm"1 and e ca. 0. epr signal intensity measurements at x-band in the range 4 < t < 295 k indicated that j0 = "283 ± 5 cm"1. a higher limit |j′| < 5×10-3 cm-1 for the interdinuclear exchange coupling between neighbor units at ca.14.24 ? was estimated from the angular variation of the single crystal spectra around the magic angles. the results are discussed in terms of the structure of the dinuclear unit and the bridges connecting cuii ions and compared with values reported for similar compounds.
Nuevos sistemas para la administración de activos a la dermis
Martínez,B; Della Torre,A; Nacucchio,M;
Revista argentina de dermatolog?-a , 2010,
Abstract: the present work review the state of the art technologies, for the administration of drugs and actives to the dermis. different mechanisms will be discussed as well many examples are included, to summarize the potential of this new pharmaceutical dosage forms for therapeutic, as well cosmetic applications.
Nuevos sistemas para la administración de activos a la dermis New drug active delivery systems for dermal controlled release
B Martínez,A Della Torre,M Nacucchio
Revista Argentina de Dermatología , 2010,
Abstract: El presente trabajo tiene por objetivo la actualización de las diferentes tecnologías, aplicadas para la administración selectiva y controlada de moléculas con actividad biológica a la piel. Se explican los distintos mecanismos y racionales aplicables, así como el potencial de estas modernas formas farmacéuticas para su uso en aplicaciones terapéuticas y cosméticas. The present work review the state of the art technologies, for the administration of drugs and actives to the dermis. Different mechanisms will be discussed as well many examples are included, to summarize the potential of this new pharmaceutical dosage forms for therapeutic, as well cosmetic applications.
Characterisation of the mixing height temporal evolution by means of a laser dial system in an urban area – intercomparison results with a model application
M. A. García, M. L. Sánchez, B. de Torre,I. A. Pérez
Annales Geophysicae (ANGEO) , 2007,
Abstract: Measurements of vertical and temporal variations in ozone and aerosol as extinction over an urban area in Segovia, central Spain, were performed during two summer months in 2004 by means of a commercial Nd:YAG laser DIAL remote sensing system. The Differential Absorption Lidar (DIAL) technique was applied and its description is given. From the profile data, a practical determination of mixing height may be derived. A diurnal evolution for the whole dataset is observed, the highest mean mixing height being reached at 16:00 GMT, 2150 m. The presence of a double-layer structure at night was observed and the layers can be considered residual. On average, the lower layer is formed at 670 m and the upper layer yielded mean heights ranging between 1270 and 1390 m. The estimated mixing heights during the day are also compared with those obtained from the Lagrangian HYSPLIT model. The results show good statistical agreement between both approaches, mainly in the early afternoon, with correlation coefficients around 0.7.
Analysis of wind data in the low atmosphere from a RASS sodar
I. A. Pérez, M. A. García, M. L. Sánchez,B. de Torre
Annales Geophysicae (ANGEO) , 2006,
Abstract: This paper focuses on the ability of a sodar to describe some characteristics of the atmospheric vertical structure and presents some techniques for meteorological data evaluation. The measuring campaign took place in April 2001 and consisted of 10-min averages covering the lower atmosphere from 40 to 500 m at 20-m levels. Three methods were considered, the first of which was a scalar analysis performed using a combination of wind and temperature median profiles. A noticeable contrast between day and night was obtained. Flat wind profiles during the day were a consequence of prevailing convective conditions that determined thermal turbulence. A stable layer above 260 m capped the unstable layer situated below and guaranteed the stability of the boundary layer. During the night, the presence of a low level jet was the most significant feature. The height of the core was 340 m and the higher vertical winds defined it clearly. The second method focused on the wind vector. In this analysis, the anti-cyclonic rotation of hourly averages was considered in the lower levels where it was observed. After a translation of the origin, an empirical, robust model with two parts was then proposed for the resulting vector. The angle was described linearly and the module by a second order model for cylindrical data. Finally, as a third method, three regression analyses were investigated: vectorial, taking every wind component separately and scalar. The two first seemed to be more complete due to their description of anti-cyclonic wind rotation when height increased. Correlation coefficients also proved to be more satisfactory. As a consequence, these techniques, although less frequently used, are more suitable to study wind in the low atmosphere.
Boundary layer structure and stability classification validated with CO2 concentrations over the Northern Spanish Plateau
I. A. Pérez, M. L. Sánchez, M. á. García,B. de Torre
Annales Geophysicae (ANGEO) , 2009,
Abstract: A description of the lower boundary layer is vital to enhance our understanding of dispersion processes. In this paper, Radio Acoustic Sounding System sodar measurements obtained over three years were used to calculate the Brunt-V is l frequency and the Monin-Obukhov length. The Brunt-V is l frequency enabled investigation of the structure of this layer. At night, several layers were noticeable and the maximum was observed at the first level, 40 m, whereas during the day, it was present at about 320 m. The Monin-Obukhov length was calculated with the four first levels measured, 40–100 m, by an original iterative method and used to establish four stability classes: drainage, extremely stable, stable and unstable. Wind speed and temperature median profiles linked to these classes were also presented. Wind speeds were the lowest, but temperatures were the highest and inversions were intense at night in drainage situations. However, unstable situations were linked to high wind speeds and superadiabatic temperature profiles. Detrended CO2 concentrations were used to determine the goodness of the classification proposed evidencing values which under drainage at night in spring were nearly 28 ppm higher than those corresponding to unstable situations. Finally, atmosphere structure was presented for the proposed stability classes and related with wind speed profiles. Under extremely stable situations, low level jets were coupled to the surface, with median wind speeds below 8 m s 1 and cores occasionally at 120 m. However, jets were uncoupled in stable situations, wind speed medians were higher than 11 m s 1 and their core heights were around 200 m.
DNA Topoisomerase II Modulates Insulator Function in Drosophila
Edward Ramos,Eduardo A. Torre,Ashley M. Bushey,B. V. Gurudatta,Victor G. Corces
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016562
Abstract: Insulators are DNA sequences thought to be important for the establishment and maintenance of cell-type specific nuclear architecture. In Drosophila there are several classes of insulators that appear to have unique roles in gene expression. The mechanisms involved in determining and regulating the specific roles of these insulator classes are not understood. Here we report that DNA Topoisomerase II modulates the activity of the Su(Hw) insulator. Downregulation of Topo II by RNAi or mutations in the Top2 gene result in disruption of Su(Hw) insulator function. This effect is mediated by the Mod(mdg4)2.2 protein, which is a unique component of the Su(Hw) insulator complex. Co-immunoprecipitation and yeast two-hybrid experiments show that Topo II and Mod(mdg4)2.2 proteins directly interact. In addition, mutations in Top2 cause a slight decrease of Mod(mdg4)2.2 transcript but have a dramatic effect on Mod(mdg4)2.2 protein levels. In the presence of proteasome inhibitors, normal levels of Mod(mdg4)2.2 protein and its binding to polytene chromosomes are restored. Thus, Topo II is required to prevent Mod(mdg4)2.2 degradation and, consequently, to stabilize Su(Hw) insulator-mediated chromatin organization.
Scale-by-scale analysis of probability distributions for global MODIS-AQUA cloud properties: how the large scale signature of turbulence may impact statistical analyses of clouds
M. de la Torre Juárez, A. B. Davis,E. J. Fetzer
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2011,
Abstract: Means, standard deviations, homogeneity parameters used in models based on their ratio, and the probability distribution functions (PDFs) of cloud properties from the MODerate resolution Infrared Spectrometer (MODIS) are estimated globally as function of averaging scale varying from 5 to 500 km. The properties – cloud fraction, droplet effective radius, and liquid water path – all matter for cloud-climate uncertainty quantification and reduction efforts. Global means and standard deviations are confirmed to change with scale. For the range of scales considered, global means vary only within 3% for cloud fraction, 7% for liquid water path, and 0.2% for cloud particle effective radius. These scale dependences contribute to the uncertainties in their global budgets. Scale dependence for standard deviations and generalized flatness are compared to predictions for turbulent systems. Analytical expressions are identified that fit best to each observed PDF. While the best analytical PDF fit to each variable differs, all PDFs are well described by log-normal PDFs when the mean is normalized by the standard deviation inside each averaging domain. Importantly, log-normal distributions yield significantly better fits to the observations than gaussians at all scales. This suggests a possible approach for both sub-grid and unified stochastic modeling of these variables at all scales. The results also highlight the need to establish an adequate spatial resolution for two-stream radiative studies of cloud-climate interactions.
Cloud-type dependencies of MODIS and AMSR-E liquid water path differences
M. de la Torre Juárez,B. H. Kahn,E. J. Fetzer
Atmospheric Chemistry and Physics Discussions , 2009,
Abstract: Comparisons of cloud liquid water path (LWP) retrievals are presented from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Microwave Scanning Radiometer (AMSR-E) located aboard the Aqua spacecraft. LWP differences as a function of cloud top height, cloud fraction, cloud top temperature, LWP, cloud effective radius and cloud optical thickness are quantified in most geophysical conditions. The assumption of vertically homogeneous distributions of cloud water content in the MODIS LWP retrieval yields a slightly poorer agreement than the assumption of stratified cloud liquid water. Furthermore, for a fixed cloud top pressure, the cloud top temperature can lead to sign changes in the LWP difference. In general, AMSR-E LWP is larger than MODIS for small cloud fractions, low values of LWP, and warmer cloud top temperatures. On the other hand, clouds with optical thicknesses above 20 lead to larger MODIS LWP. Using cloud optical thickness as a proxy for cloud type, deep convective clouds and stratus are shown to have the poorest agreement between AMSR-E and MODIS LWP. Particularly large differences are also found at latitudes poleward of 50°. The results of this work help characterize the scene- and cloud-dependent performance of microwave and visible/near infrared retrievals of LWP.
Intrinsic switching field distribution of arrays of Ni80Fe20 nanowires probed by $\mathit{in\, situ}$ magnetic force microscopy
M. R. Tabasum,F. Zighem,J. De La Torre Medina,L. Piraux,B. Nysten
Physics , 2012, DOI: 10.1007/s10948-012-1975-5
Abstract: The progress of magnetization reversal of weakly packed ferromagnetic Ni80Fe20 nanowire arrays of different diameters (40, 50, 70 and 100 nm) electrodeposited in polycarbonate membranes was studied by magnetic force microscopy (MFM). For such a low packing density of nanomagnets, the dipolar interactions between neighbouring wires can be neglected. The intrinsic switching field distribution has been extracted from in situ MFM images and its width was found to be considerably smaller than for densely packed nanowire arrays.
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