Dynamic strength of a modified W-beam BCT trailing-end termination system

W-beam systems utilize end-terminal anchorages to develop tension upstream and downstream of an impact event. However, the capacities of the anchorage components under impact loading are not well known. One such W-beam end anchorage system, the Midwest guardrail system (MGS) trailing-end anchorage, was evaluated using three dynamic component tests _ a soil foundation tube pull test, a breakaway cable terminal (BCT) post splitting test, and an MGS end anchorage system pull test. The peak load recorded during a soil foundation tube test was 193 kN at 56 mm deflection, as measured at the ground line. BCT posts split at loads of 17.8 and 32.9 kN. The end-anchorage tensile capacity was 156 kN, dissipating 64.7 kJ. Results from the component tests were also used to create and validate nonlinear finite element models of the components in order to be used for future design and analysis of end anchorages

Design and Testing of a Concrete Safety Barrier for Use on a Temporary FRP Composite Bridge Deck

Fiber-reinforced polymer (FRP) composite materials can be used for the fabrication of lightweight, corrosion-resistant honeycomb sandwich panels, representing a convenient and economical alternative to traditional steel RC for bridge decks. Composite panels are particularly advantageous for the construction of temporary bridge structures in terms of both ease of construction and reusability of panels. Although FRP sandwich panels have been considered for the construction of bridge decks, no barrier system has been developed and crash tested for use with this specific type of deck. The objective of this research project was to develop a crashworthy concrete barrier system for use with temporary FRP composite bridge decks. Upon failure of a full-scale crash test with a New Jersey concrete safety shape barrier, an accurate analysis of the potential problems led to a series of design modifications to the barrier as well as to the attachment between the composite deck and both the bridge structure and the barrier. The second design, which used a vertical-faced barrier, was successfully crash tested according to Test-Level 3 impact safety standards set forth in the AASHTO Manual for Assessing Safety Hardware (MASH)

Comparative proteomic analysis of collection and clinical-isolate strains of psudomonas aeruginosa

Comunicaciones a congreso

Soybean Seed Lectin Prevents the Accumulation of S-Adenosyl Methionine Synthetase and the S1 30S Ribosomal Protein in <i>Bradyrhizobium japonicum</i> Under C and N Starvation

Soybean lectin (SBL) participates in the recognition between Bradyrhizobium japonicum and soybean although its role remains unknown. To search for changes in the proteome in response to SBL, B. japonicum USDA 110 was incubated for 12 h in a C- and N-free medium with or without SBL (10 μg ml ⁻¹), and the soluble protein profiles were compared. Two polypeptides, S-adenosyl-methionine synthetase (MetK) and the 30S ribosomal protein S1 (RpsA), were found only in the fractions from rhizobia incubated without SBL. Transcript levels of metK and rpsA were not correlated with polypeptide levels, indicating that there was regulation at translation. In support of this proposal, the 5′ translation initiation-region of rpsA mRNA contained folding elements as those involved in regulation of its translation in other species. Disappearance of MetK and RpsA from the soluble protein fractions of SBL-treated rhizobia suggests that SBL might have attenuated the nutritional stress response of B. japonicum.Instituto de Biotecnología y Biología Molecula

Abundance of the Quorum-Sensing Factor Ax21 in Four Strains of Stenotrophomonas maltophilia Correlates with Mortality Rate in a New Zebrafish Model of Infection

Stenotrophomonas maltophilia is a Gram-negative pathogen with emerging nosocomial incidence. Little is known about its pathogenesis and the genomic diversity exhibited by clinical isolates complicates the study of pathogenicity and virulence factors. Here, we present a strategy to identify such factors in new clinical isolates of S. maltophilia, incorporating an adult-zebrafish model of S. maltophilia infection to evaluate relative virulence coupled to 2D difference gel electrophoresis to explore underlying differences in protein expression. In this study we report upon three recent clinical isolates and use the collection strain ATCC13637 as a reference. The adult-zebrafish model shows discrimination capacity, i.e. from very low to very high mortality rates, with clinical symptoms very similar to those observed in natural S. maltophilia infections in fish. Strain virulence correlates with resistance to human serum, in agreement with previous studies in mouse and rat and therefore supporting zebrafish as a replacement model. Despite its clinical origin, the collection strain ATCC13637 showed obvious signs of attenuation in zebrafish, with null mortality. Multilocus-sequence-typing analysis revealed that the most virulent strains, UV74 and M30, exhibit the strongest genetic similitude. Differential proteomic analysis led to the identification of 38 proteins with significantly different abundance in the three clinical strains relative to the reference strain. Orthologs of several of these proteins have been already reported to have a role in pathogenesis, virulence or resistance mechanisms thus supporting our strategy. Proof of concept is further provided by protein Ax21, whose abundance is shown here to be directly proportional to mortality in the zebrafish infection model. Indeed, recent studies have demonstrated that this protein is a quorum-sensing-related virulence factor