Ensayos comparativos a escala real de cubierta formada por correas Z conformadas en frío

The use of cold formed Z purlins is common in industrial construction. However, due to the high uncertainty of such structures and elements, and their tendency to suffer local instability phenomena, it is very interesting to have actual test results. In this article, the results of two tests of full-scale roofs are provided. The roofs are loaded with water pool until the collapse of the structure, thereby determining its ultimate strength and behavior up to this point, and comparing the results with those obtained using different standard methodologies in the field of structural engineering. It is concluded that the behavior in the linear range during testing is very similar to the predicted analytically, and a very high ultimate strength is observed until the collapse of the structure in both tests.<br><br>La utilización de correas Z conformadas en frio es muy habitual en construcción industrial. No obstante, debido al alto grado de incertidumbre de este tipo de estructuras y elementos, y a su tendencia a sufrir fenómenos de inestabilidad local, resulta muy interesante contar con resultados de ensayos reales. En este artículo, se aportan los resultados de dos ensayos de cubiertas Deck a escala real. La cubierta se carga mediante balsa de agua hasta llegar al colapso de la estructura, determinando tanto su resistencia última, como el comportamiento hasta este punto. Adicionalmente se comparan los resultados de los ensayos con los obtenidos mediante diferentes metodologías habituales en el ámbito de la ingeniería estructural. Se concluye que el comportamiento en el rango lineal durante los ensayos es muy similar al predicho analíticamente, y se observa una muy alta resistencia última hasta el colapso de la estructura en ambos ensayos

Adsorption of hydrogen sulphide on Metal-Organic Frameworks

Three new sets of interatomic potentials to model hydrogen sulphide (H2S) have been fitted. One of them is a 3-sites potential (which we named 3S) and the other two are 5-sites potentials (which we named 5S and 5Sd). The molecular dipole of the 3S and 5S potentials is 1.43 D, which is the value usually employed for H2S potentials, while the dipole of the 5Sd is the dipole measured experimentally for the H2S molecule, circa 0.974 D. The interatomic potentials parameters were obtained by fitting the experimental vapour-liquid equilibrium, vapour pressure and liquid density curves. The potential parameters fitted so far for H2S have been obtained applying long-range corrections to the Lennard-Jones energy. For that reason, when a cut and shift of the Lennard-Jones potentials is applied they do not yield the correct results. We employed a cut and shift of the Lennard-Jones potentials in the fitting procedure, which facilitates the use of the new potentials to model H2S adsorption on systems such as Metal-Organics Frameworks (MOFs). We have employed the newly developed potentials to study the adsorption of H2S on Cu-BTC, MIL-47 and IRMOF-1 and the results agree with the available electronic structures calculations. All calculations (both quantum and interatomic potential-based) predict that H2S does not bind to the Cu atoms in Cu-BTC

Morfología de vertientes y neotectónica en el Macizo de Javalambre (provincia de Teruel)

[Resumen] El modelado actual de las vertientes del macizo de Javalambre es consecuencia de tres tipos principales de procesos que actúan a partir de su elevación a comienzos del Plioceno -superior: (a) la dinámica periglaciar, (b) una etapa de activida~ tect6nica ocurrida hacia el Pleistoceno medio-superior, y (c) deslizamientos gravitacionales, translacionales y rotacionales producidos a favor de un sustrato plástico en las áreas de mayor incisión de la red -fluvial.Abstract] The present slope form in Javalambre area results from three principal types of processes which are active after its elevation in the early Upper Pliocene: (a) periglacial dynamics, (b) a tectonic phase in Middle-Upper Pleistocene, and (c) gravitational, translational and rotational landslides generated over plastic rocks in zones with a intensive fluvial incisio

Seasonality of picophytoplankton chlorophyll a and biomass in the central Cantabrian Sea, southern Bay of Biscay

Seasonal changes in the abundance and biomass of cyanobacteria (Synechococcus and Prochlorococcus) and picoeukaryotes were studied by flow cytometry in the upper layers of the central Cantabrian Sea continental shelf, from April 2002 to April 2006. The study area displayed the typical hydrographic conditions of temperate coastal zones. A marked seasonality of the relative contribution of prokaryotes and eukaryotes was found. While cyanobacteria were generally more abundant for most of the year (up to 2.4 105 cells mL− 1), picoeukaryotes dominated the community (up to 104 cells mL− 1) from February to May. The disappearance of Prochlorococcus from spring through summer is likely related to shifts in the prevailing current regime. The maximum total abundance of picophytoplankton was consistently found in late summer–early autumn. Mean photic-layer picoplanktonic chlorophyll a ranged from 0.06 to 0.53 µg L− 1 with a relatively high mean contribution to total values (33 ± 2% SE), showing maxima around autumn and minima in spring. Biomass (range 0.58–40.16 mg C m− 3) was generally dominated by picoeukaryotes (mean ± SE, 4.28 ± 0.27 mg C m− 3) with an average contribution of cyanobacteria of 30 ± 2%. Different seasonality of pigment and biomass values resulted in a clear temporal pattern of picophytoplanktonic carbon to chlorophyll a ratio, which ranged from 10 (winter) to 140 (summer). This study highlights the important contribution of picoplanktonic chlorophyll a and carbon biomass in this coastal ecosystem.Versión del edito

Enhancement of the stability of the flow focusing technique for low-viscosity liquids

Article number 115039We propose a modified flow focusing configuration to produce low-viscosity microjets at much smaller flow rates than those reached by the standard configuration. In the modified flow focusing device, a sharpened rod blocks the recirculation cell appearing in the tapering liquid meniscus for low flow rates, which considerably improves its stability. We measured the minimum flow rates attainable with the modified configuration and compared the results with the corresponding values for the standard technique. For moderate and large applied pressure drops, the minimum flow rate reached with the modified configuration was about five times smaller than its counterpart in the standard configuration. The Weber numbers of the jets produced with the modified flow focusing configuration were considerably smaller than those with the standard technique. Numerical simulations were conducted to show how the presence of the inner rod substantially changes the flow pattern in the liquid meniscus.Ministerio de Ciencia y Educación, Junta de Extremadura y Junta de Andalucía (España) DPI2010-21103, GR10047 y P08-TEP-0412

Controlled cavity collapse: scaling laws of drop formation

The formation of transient cavities at liquid interfaces occurs in an immense variety of natural processes, among which the bursting of surface bubbles and the impact of a drop on a liquid pool are salient. The collapse of a surface liquid cavity is a well documented natural process that leads to the ejection of a thin and fast jet. Droplets generated through this process can be one order of magnitude smaller than the cavity's aperture, and they are consequently of interest in drop on demand inkjet applications. In this work, the controlled formation and collapse of a liquid cavity is analyzed, and the conditions for minimizing the resulting size and number of ejected drops are determined. The experimental and numerical models are simple and consist of a liquid reservoir, a nozzle plate with the discharge orifice, and a moving piston actuated by single half-sine-shaped pull-mode pulses. The size of the jetted droplet is described by a physical model resulting in a scaling law that is numerically and experimentally validatedRoyal Society (UF120319, URF\R\180016, and RGF\EA\180061)John Fell Oxford University Press Research Fund (0005176)EPSRC – UK (EP/P024173/1)Ministerio de Economía y Competitividad, Plan Estatal 2013–2016 Retos, project DPI2013-46485-C3-1-

4D monitoring of active sinkholes with a Terrestrial Laser Scanner (TLS): A Case study in the evaporite karst of the Ebro Valley, NE Spain

This work explores, for the first time, the application of a Terrestrial Laser Scanner (TLS) and a comparison of point clouds in the 4D monitoring of active sinkholes. The approach is tested in three highly-active sinkholes related to the dissolution of salt-bearing evaporites overlain by unconsolidated alluvium. The sinkholes are located in urbanized areas and have caused severe damage to critical infrastructure (flood-control dike, a major highway). The 3D displacement models derived from the comparison of point clouds with exceptionally high spatial resolution allow complex spatial and temporal subsidence patterns within one of the sinkholes to be resolved. Detected changes in the subsidence activity (e.g., sinkhole expansion, translation of the maximum subsidence zone, development of incipient secondary collapses) are related to potential controlling factors such as floods, water table changes or remedial measures. In contrast, with detailed mapping and high-precision leveling, the displacement models, covering a relatively short time span of around 6 months, do not capture the subtle subsidence (< 0.6-1 cm) that affects the marginal zones of the sinkholes, precluding precise mapping of the edges of the subsidence areas. However, the performance of TLS can be adversely affected by some methodological limitations and local conditions: (1) limited accuracy in large investigation areas that require the acquisition of a high number of scans, increasing the registration error; (2) surface changes unrelated to sinkhole activity (e.g., vegetation, loose material); (3) traffic-related vibrations and wind blast that affect the stability of the scanner

Ser o no ser y estar o no estar en Internet.

Objective: To reflect the situation of the websites of the hospital libraries in Spain in 2003. Material and methods: The websites of the hospital libraries have been located through C-17 directory, various hospital directories and searching Google, Altavista and Alltheweb. It has been applied the questionnaire of evaluation of websites with pondered punctuation by Lluís Codina. Visibility indicators have been obtained as well as accessibility according TAW. Results: From the C-17 catalogue have been retrieved 176 hospital libraries, of which 13 have a website; we added to these other 19 websites found through other directories and search engines. Of those 32 websites, 2 were not active; the remaining 30 were analyzed. Five of them passed the Codina's test of level I. In the TAW priority level 1, the problems detected automatically oscillated between 0 and 77. Conclusions: The results show the low number of hospital libraries with websites on the internet. The websites quality should be improved following the recommendations of the checkup lists to evaluate digital resources on the internet. The scarce visibility of these webs, hinders greatly its localization. On the other hand, the low accessibility rate of these webs blocks their visualization to handicapped people

The wideband backend at the MDSCC in Robledo. A new facility for radio astronomy at Q- and K- bands

The antennas of NASA's Madrid Deep Space Communications Complex (MDSCC) in Robledo de Chavela are available as single-dish radio astronomical facilities during a significant percentage of their operational time. Current instrumentation includes two antennas of 70 and 34 m in diameter, equipped with dual-polarization receivers in K (18 - 26 GHz) and Q (38 - 50 GHz) bands, respectively. We have developed and built a new wideband backend for the Robledo antennas, with the objectives (1) to optimize the available time and enhance the efficiency of radio astronomy in MDSCC; and (2) to tackle new scientific cases impossible to that were investigated with the old, narrow-band autocorrelator. The backend consists of an IF processor, a FFT spectrometer (FFTS), and the software that interfaces and manages the events among the observing program, antenna control, the IF processor, the FFTS operation, and data recording. The whole system was end-to-end assembled in August 2011, at the start of commissioning activities, and the results are reported in this paper. Frequency tunings and line intensities are stable over hours, even when using different synthesizers and IF channels; no aliasing effects have been measured, and the rejection of the image sideband was characterized. The first setup provides 1.5 GHz of instantaneous bandwidth in a single polarization, using 8192 channels and a frequency resolution of 212 kHz; upgrades under way include a second FFTS card, and two high-resolution cores providing 100 MHz and 500 MHz of bandwidth, and 16384 channels. These upgrades will permit simultaneous observations of the two polarizations with instantaneous bandwidths from 100 MHz to 3 GHz, and spectral resolutions from 7 to 212 kHz.Comment: 9 pages, 8 figures. Accepted to Astronomy and Astrophysic

Stain-free detection as loading control alternative to Ponceau and housekeeping protein immunodetection in Western blotting

The authors want to thank the input of Arnaud Remy and Enrique Orozco of Bio-Rad Laboratories. This study was supported by the Ministry of Science and Innovation (SAF2011-22922 and SAF2011-22812), and by funds from Junta de Andalucia (CTS6736 and CTS164). B. Rivero and A. Anzola were supported by fellowships of the Ministry of Education and Science of Spain and Junta de Andalucia, respectively. CIBERehd is funded by the Instituto de Salud Carlos III.It is currently a routine practice to require a measurement of a housekeeping reference, including actin, glyceraldehyde-3-phosphate dehydrogenase, β-tubulin, among others, in Western blots, as it is the rule in RNA blots. Reversible Ponceau staining has been applied successfully to check equal loading of gels. Here we test a new technique, with the Stain-Free gels from Bio-Rad, against both Ponceau staining and housekeeping protein immunodetection under different conditions. Our results show that Stain-Free gels outperform Ponceau staining and that both are more consistent than housekeeping proteins as a loading control.Spanish Government SAF2011-22922 SAF2011-22812Junta de Andalucia CTS6736 CTS164Instituto de Salud Carlos II