Viscoelastic vibration damping identification methods. Application to laminated glass.

Laminatedglass is composed of two glass layers and a thin intermediate PVB layer, strongly influencing PVB's viscoelastic behaviour its dynamic response. While natural frequencies are relatively easily identified even with simplified FE models, damping ratios are not identified with such an ease. In order to determine to what extent external factors influence dampingidentification, different tests have been carried out. The external factors considered, apart from temperature, are accelerometers, connection cables and the effect of the glass layers. To analyse the influence of the accelerometers and their connection cables a laser measuring device was employed considering three possibilities: sample without instrumentation, sample with the accelerometers fixed and sample completely instrumented. When the sample is completely instrumented, accelerometer readings are also analysed. To take into consideration the effect of the glass layers, tests were realised both for laminatedglass and monolithic samples. This paper presents in depth data analysis of the different configurations and establishes criteria for data acquisition when testing laminatedglass

The influence of holes in the mechanical properties of EWT solar cells

EWT back contact solar cells are manufactured from very thin silicon wafers. These wafers are drilled by means of a laser process creating a matrix of tiny holes with a density of approximately 125 holes per square centimeter. Their influence in the stiffness and mechanical strength has been studied. To this end, both wafers with and without holes have been tested with the ring on ring test. Numerical simulations of the tests have been carried out through the Finite Element Method taking into account the non-linearities present in the tests. It's shown that one may use coarse meshes without holes to simulate the test and after that sub models are used for the estimation of the stress concentration around the holes

Real-time RT-PCR analysis of mRNA decay: half-life of Beta-actin mRNA in human leukemia CCRF-CEM and Nalm-6 cell lines

BACKGROUND: We describe an alternative method to determine mRNA half-life (t(1/2)) based on the Real-Time RT-PCR procedure. This approach was evaluated by using the β-actin gene as a reference molecule for measuring of mRNA stability. RESULTS: Human leukemia Nalm-6 and CCRF-CEM cells were treated with various concentrations of Actinomycin D to block transcription and aliquots were removed periodically. Total RNA was isolated and quantified using the RiboGreen(®) fluorescent dye with the VersaFluor Fluorometer System. One μg of total RNA was reverse transcribed and used as template for the amplification of a region of the β-actin gene (231 bp). To generate the standard curve, serial ten-fold dilutions of the pBactin-231 vector containing the cDNA amplified fragment were employed, β-actin mRNAs were quantified by Real-Time RT-PCR using the SYBR(®) Green I fluorogenic dye and data analyzed using the iCycle iQ system software. Using this method, the β-actin mRNA exhibited a half-life of 6.6 h and 13.5 h in Nalm-6 and CCRF-CEM cells, respectively. The t(1/2) value obtained for Nalm-6 is comparable to those estimated from Northern blot studies, using normal human leukocytes (5.5 h). CONCLUSIONS: We have developed a rapid, sensitive, and reliable method based on Real-Time RT-PCR for measuring mRNA half-life. Our results confirm that β-actin mRNA half-life can be affected by the cellular growth rate

The Impact of Local Power Balance and Link Reliability on Blackout Risk in Heterogeneous Power Transmission Grids

Many critical infrastructures such as the power transmission grid are heterogeneous both in their basic structure and in some of their underlying characteristics, This heterogeneity can be good for system robustness if it reduces the spread of failures or bad if it adds risk or vulnerability to the system. In this paper we investigate the effect of heterogeneity in the strength of the links between parts of the system network structures, as well as the balance of local generation and demand, on the robustness of the power transmission grid using the OPA complex system model of the power transmission system. It is found that increasing or decreasing the reliability of the links between parts of the grid changes the likelihood of different size failures with neither being optimal for all sizes. Furthermore, imbalances between load and generation in the local regions further degrades the system reliability

OPTIMIZING THE DENSITY OF HOLES OF EWT SOLAR CELLS TAKING INTO CONSIDERATION MECHANICAL ASPECTS

ABSTRACT: EWT solar cells start from drilled wafers with approximately 100 holes/cm 2 . These holes act as stress concentrators leading to a reduction in the mechanical strength of this type of wafers. The viability of cells with higher density of holes has been studied. To this end, sets of wafers with different density of holes have been characterized. The ring on ring test has been employed and FE models have been developed to simulate the test. The statistical evaluation permits to draw conclusions about the reduction of the strength depending on the density of holes. Moreover, the stress concentration around the holes has been studied by means of the FE method employing the sub-modeling technique. The maximum principal stress of EWT wafers with twice the density of holes of commercial ones is almost the same. However, the mutual interaction between the stress concentration effects around neighboring holes is only observed for wafers with a density of 200 holes/cm 2

Nota corta. Detección mediante PCR multiplex y caracterización de cepas no toxigénicas de Pseudomonas syringae pv. phaseolicola de distintas zonas de España

The efficient control of halo blight, caused by Pseudomonas syringae pv. phaseolicola, is primarily based on the use of pathogen-free seed. Detection of the pathogen in seeds is currently carried out with high-sensitive methods based on the detection by PCR of genes involved in the biosynthesis of phaseolotoxin, which was believed to be produced by all strains of the pathogen with epidemiological importance. However, field epidemics of halo blight in the county of Castilla y León, Spain, are often associated to nontoxigenic isolates of P. syringae pv. phaseolicola, which cannot be detected using current molecular and serological methods. The results presented in this work show the existence of nontoxigenic isolates of P. syringae pv. phaseolicola in areas other than Castilla y León, indicating the need to establish a reliable methodology for seed certification. A simple two-step methodology is presented with the aim to identify both types of isolates that is based on a multiplex enrichment PCR of seed soakates and on pathogenicity assays.El control eficiente de la grasa de la judía causada por Pseudomonas syringae pv. phaseolicola se basa principalmente en la utilización de semilla libre del patógeno. La detección del patógeno en semilla se efectúa mediante métodos altamente sensibles basados en la detección por PCR de los genes responsables de la biosíntesis de la faseolotoxina, la cual, hasta ahora, se consideraba que era sintetizada por todas las cepas del patógeno con importancia epidemiológica. Sin embargo, en la Comunidad de Castilla y León, España, las epidemias de grasa de la judía en campo se asocian frecuentemente con cepas no toxigénicas de P. syringae pv. phaseolicola, que no pueden ser detectadas con los métodos moleculares y serológicos actuales. Los resultados presentados en este trabajo demuestran la existencia de aislados no toxigénicos de P. syringae pv. phaseolicola en zonas distintas de Castilla y León, lo que implica la necesidad de establecer una metodología fiable para la certificación de semillas de judía. Con este propósito, se presenta un sencillo protocolo en dos fases que permite la identificación de los dos tipos de aislados, y que se basa en una PCR multiplex con enriquecimiento a partir de extractos de semilla y en ensayos de patogenicidad