A Paris Law Based Mesh Independent Numerical Methodology for the Simulation of Fatigue Driven Delamination in Composites

Delamination evolution under cyclic loading is one of the most important research topics for the application of composite materials to aerospace, naval, automotive and, in general, transportation fields. Large experimental campaigns are needed to assess the fatigue behavior of Carbon Fiber Reinforced Polymers (CFRPs), which may result extremely time and cost consuming. Nevertheless, composite materials design needs to take into account the evolution of fatigue driven damage. Subsequently, the development of efficient and robust computational finite element methodologies to evaluate progression of delamination in composite structural components subjected to cyclic loading conditions has become relevant. In this paper, a numerical finite element procedure able to simulate the fatigue driven delamination growth is introduced. A Paris-law based cycle jump strategy, combined with the Virtual Crack Closure Technique (VCCT) approach, has been implemented in the commercial Finite Element Code ANSYS MECHANICAL via the Ansys Parametric Design Language (APDL). The main advantages of the proposed numerical procedure, named FT-SMXB, are related to its independence on the time step and element size in the frame of incremental analyses. The procedure has been preliminary validated, in this research study, at coupon level, by comparing the numerical results to literature experimental data on a unidirectional graphite/epoxy Double Cantilever Beam (DCB) specimen. The significant agreement between the obtained numerical results and the literature experimental benchmark data confirms the accuracy and the potential of the proposed methodology

Climatology of the Northern-Central Adriatic Sea

It is well know that the ocean processes exert a great influence on global climate as well as affect the local climate of coastal areas (Russo et al., 2002). Within the Mediterranean region (see Fig. 1a), the presence of the Adriatic Sea influences the atmospheric properties of the surrounding regions over long and short time-scales, and has obviously a relevant influence on human activities and ecosystems (Boldrin et al., 2009).https://digitalcommons.usu.edu/modern_climatology/1006/thumbnail.jp

07 Climatology of the Northern-Central Adriatic Sea

It is well know that the ocean processes exert a great influence on global climate as well as affect the local climate of coastal areas (Russo et al., 2002). Within the Mediterranean region (see Fig. 1a), the presence of the Adriatic Sea influences the atmospheric properties of the surrounding regions over long and short time-scales, and has obviously a relevant influence on human activities and ecosystems (Boldrin et al., 2009).https://digitalcommons.usu.edu/modern_climatology/1006/thumbnail.jp

Big Data in Critical Infrastructures Security Monitoring: Challenges and Opportunities

Critical Infrastructures (CIs), such as smart power grids, transport systems, and financial infrastructures, are more and more vulnerable to cyber threats, due to the adoption of commodity computing facilities. Despite the use of several monitoring tools, recent attacks have proven that current defensive mechanisms for CIs are not effective enough against most advanced threats. In this paper we explore the idea of a framework leveraging multiple data sources to improve protection capabilities of CIs. Challenges and opportunities are discussed along three main research directions: i) use of distinct and heterogeneous data sources, ii) monitoring with adaptive granularity, and iii) attack modeling and runtime combination of multiple data analysis techniques.Comment: EDCC-2014, BIG4CIP-201

Hybridase activity of human ribonuclease-1 revealed by a real-time fluorometric assay

Human ribonuclease-1 (hRNase-1) is an extracellular enzyme found in exocrine pancreas, blood, milk, saliva, urine and seminal plasma, which has been implicated in digestion of dietary RNA and in antiviral host defense. The enzyme is characterized by a high catalytic activity toward both single-stranded and double-stranded RNA. In this study, we explored the possibility that hRNase-1 may also be provided with a ribonuclease H activity, i.e. be able to digest the RNA component of RNA:DNA hybrids. For this purpose, we developed an accurate and sensitive real-time RNase H assay based on a fluorogenic substrate made of a 12 nt 5′-fluorescein-labeled RNA hybridized to a complementary 3′-quencher-modified DNA. Under physiological-like conditions, hRNase-1 was found to cleave the RNA:DNA hybrid very efficiently, as expressed by a k(cat)/K(m) of 330 000 M(−1) s(−1), a value that is over 180-fold higher than that obtained with the homologous bovine RNase A and only 8-fold lower than that measured with Escherichia coli RNase H. The kinetic characterization of hRNase-1 showed that its hybridase activity is maximal at neutral pH, increases with lowering ionic strength and is fully inhibited by the cytosolic RNase inhibitor. Overall, the reported data widen our knowledge of the enzymatic properties of hRNase-1 and provide new elements for the comprehension of its biological function

RNA Interference in Mammalia Cells by RNA-3’-PNA Chimeras

The discovery of siRNAs as the mediators of RNA interference has led to an increasing interest in their therapeutic applications. Chemical modifications are introduced into siRNAs to optimize the potency, the stability and the pharmacokinetic properties in vivo. Here, we synthesize and test the effects of RNA-3’-PNA chimeras on siRNA functioning and stability. We demonstrate that the chemical modifications are compatible with the siRNA machinery, because all the PNA-modified siRNAs can efficiently mediate specific gene silencing in mammalian cells. Furthermore, we find that the modification on the sense strand of siRNA results in an increased persistence of the activity, whereas modification on both strands results in enhanced nuclease resistance in serum

Spring 2009 water mass distribution, mixing and transport in the southern Adriatic after a low production of winter dense waters

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PROTEOMICS AS USEFUL TOOL FOR STUDING BIOMARKERS OF EARLY EXPOSURE TO POLYCHLORINATED BIPHENILS

Polychlorinated biphenyls (PCBs) are toxic persistent organic pollutants present in the hydrosphere. Mussels are used as sentinel organisms for the monitoring of marine pollution for their ability to bioaccumulate contaminants, their sessile nature, filter-feeding habits and widespread distribution. Alteration in protein expression is often indicative of toxic exposure or effect and changes in protein expression profiles derived from environmental stress may be used for the identification of novel biomarkers. In this study, proteomics has been used in mussels as a preliminary screening of quantitative changes in protein expression caused by a mixture of PCBs, potentially useful as new biomarkers, following the identification of the proteins more drastically altered. Our data demonstrated that proteomic approach represents a valuable tool for identifying biomarkers of exposure to environmental contaminants

LEVELS OF HEAVY METALS IN ITALIAN MARKETED CANNED TUNA

Fish products are essential and irreplaceable components of human diet; nevertheless, they could result in a risk to the health of consumers due to the potential content of some xenobiotics such as heavy metals and persistent organic contaminants (Debeka et al., 2004; Storelli et al., 2005). Constant control network and surveys are valuable tools in order to prevent such risk and to ensure product quality and consumers??? safety. The aim of the current study was to measure the levels of some heavy metals (Hg, Pb, Cd) in samples of marked canned tuna in olive oil. The results showed that levels of Cd and Hg were always within the law limits and, in many samples, below the detection limit. Pb was found in concentrations exceeding the law limits in 9.8% of the analyzed samples. In conclusion, the results of the current study, quite reassuring in terms of food safety, highlighted the need to constantly monitor the levels of some chemical contaminants in fish products such as heavy metals that might endanger the health of the consumers