Shear strengthening masonry panels with sheet glass-fiber reinforced polymer

none4This paper investigates strengthening masonry walls using glass-fiber reinforced polymer (GFRP) sheets. An experimental research program was undertaken. Both clay and concrete brick specimens were tested, with and without GFRP strengthening. Singlesided strengthening was considered, as it is often not practicable to apply the reinforcement to both sides of a wall. Static tests were carried out on six masonry panels, under a combination of vertical preload, and in-plane horizontal shear loading. The mechanisms by which load was carried were observed, varying from the initial, uncracked state, to the final, fully cracked state. The results demonstrate that a significant increase of the in-plane shear capacity of masonry can be achieved by bonding GFRP sheets to the surface of masonry walls. The experimental data were used to assess the effectiveness of the GFRP strengthening, and suggestions are made to allow the test results to be used in the design of sheet GFRP strengthening for masonry structures.noneSTRATFORD T.; PASCALE G.; MANFRONI O.; BONFIGLIOLI B.STRATFORD T.; PASCALE G.; MANFRONI O.; BONFIGLIOLI B

Design and synthesis of wm5 analogues as HIV-1 TAR RNA binders

The 6-aminoquinolone WM5, previously identified by us, is among the most selective small molecules known as TAR RNA binders to show anti-HIV activity. Methods: Starting from WM5, a series of analogues modified at N-1, C-6 or C-7 position was prepared by inserting guanidine or amidine groups as well as other protonable moieties intended to electrostatically bind the phosphate backbone of TAR. All the compounds were tested for their ability to inhibit HIV-1 replication in MT-4 cells and in parallel for their cytotoxicity. The active compounds were also evaluated for their ability to interfere with the formation of the Tat-TAR complex using a Fluorescence Quenching Assay (FQA). Results: Some of the synthesized compounds showed an anti-HIV-1 activity in the sub-micromolar range with the naphthyridone derivatives being the most potent. Three of the synthesized derivatives were able to interact with the Tat-TAR complex formation presenting Ki values improved as compared to the values obtained with WM5. Conclusion: The addition of a pyridine-based protonable side chain at the N-1 position of the quinolone/naphthyridone core imparted to the compounds the ability to interfere with Tat-TAR complex formation and HIV-1 replicatio

Comparative Structural Analysis of Human DEAD-Box RNA Helicases

DEAD-box RNA helicases play various, often critical, roles in all processes where RNAs are involved. Members of this family of proteins are linked to human disease, including cancer and viral infections. DEAD-box proteins contain two conserved domains that both contribute to RNA and ATP binding. Despite recent advances the molecular details of how these enzymes convert chemical energy into RNA remodeling is unknown. We present crystal structures of the isolated DEAD-domains of human DDX2A/eIF4A1, DDX2B/eIF4A2, DDX5, DDX10/DBP4, DDX18/myc-regulated DEAD-box protein, DDX20, DDX47, DDX52/ROK1, and DDX53/CAGE, and of the helicase domains of DDX25 and DDX41. Together with prior knowledge this enables a family-wide comparative structural analysis. We propose a general mechanism for opening of the RNA binding site. This analysis also provides insights into the diversity of DExD/H- proteins, with implications for understanding the functions of individual family members

Forced vibration tests carried out on a laminated timber footbridge: comparisons five years apart

The aim of this work concerns the analysis and comparison of those modal parameters which are obtained by assessing two forced vibration tests, experienced on a laminated timber footbridge. The two tests were carried out five years apart to verify if the dynamic characteristics of the structure change considerably during its use. In particular, modal damping of the footbridge increases (that means an effective structural deterioration), whereas modal frequencies are substantially constant . It is noticeable that the analysis of the first test [1] highlighted that the natural frequencies of the structure were included in the range between 1 and 2 Hz, more similar to the frequency of the human step. This can entail possible amplifications of the oscillations of the structure during the passing of pedestrians (low comfort level for users). The analysis of the structural durability is necessary because the ordinary maintenance of the footbridge is not usually made, although the structure is subject to hard weather condition

On site dynamic test of a long span timber footbridge

In this paper in situ dynamic test results on a long span timber footbridge are reported. As a result of evident flexibility of the structure not taken into account for during the design phase, the test engineer required a dynamic test just after footbridge concluding, with the aim to get realistic values of the main dynamic performances so as to compare them with numerical models. By means of a refined numerical model, it was so possible to analyse the structural performance under many environmental loads, namely wind, live load and earthquake

Dynamic identification of a timber footbridge subject to vibration tests

Over the last thirty years timber bridges and footbridges have been found considerable use especially by their versatility, good durability and pleasing aesthetic view. First the development of new technology and materials, as the laminated timber, second the use of innovative building, assembling and connection techniques and third the expansion of efficient, certain and inexpensive products for timber protection, have allowed the employ of this type of structure. In this paper the results obtained from two forced vibration tests, carried out in 2000 and 2005, define the dynamic behaviour of a laminated timber footbridge, which has been excited by means of vibrodyne. The first test has been made in the 2000, immediately after the building launch and before its use, whereas the second test has been replicated after five years using the same test set up adopted in the first one. The aim has been to estimate, with hindsight, the dynamic characteristics of the footbridge natural frequencies, dampings, mode shapes, etc.) and their possible variations. The free vibrations of the system, acquired during only the first test, have been analyzed afterwards to define the modal parameters through the Wavelet Transform. This kind of survey is necessary due both to the material used in the building and the particular using conditions of the footbridge: in fact, it is subjected to particular weather conditions, because it is situated near to the Adriatic Sea

Shear strengthening masonry panels with sheet glass-fiber reinforced polymer

This paper investigates strengthening masonry walls using glass-fiber reinforced polymer (GFRP) sheets. An experimental research program was undertaken. Both clay and concrete brick specimens were tested, with and without GFRP strengthening. Singlesided strengthening was considered, as it is often not practicable to apply the reinforcement to both sides of a wall. Static tests were carried out on six masonry panels, under a combination of vertical preload, and in-plane horizontal shear loading. The mechanisms by which load was carried were observed, varying from the initial, uncracked state, to the final, fully cracked state. The results demonstrate that a significant increase of the in-plane shear capacity of masonry can be achieved by bonding GFRP sheets to the surface of masonry walls. The experimental data were used to assess the effectiveness of the GFRP strengthening, and suggestions are made to allow the test results to be used in the design of sheet GFRP strengthening for masonry structures

Inhibition of Subgenomic Hepatitis C Virus RNA Replication by Acridone Derivatives: Identification of an NS3 Helicase Inhibitor

We report the synthesis and structure - activity relationship (SAR) of a large series of acridones and acridone-fragment derivatives designed on the basis of the selective antihepatitis C virus (HCV) activity shown by acridone 2, previously studied as a potential antibovine viral diarrhea virus (BVDV) compound. The evaluation of their ability to inhibit the HCV replication in Huh-5-2 cells led to the identification of new, selective inhibitors. This indicates that the acridone skeleton, when properly functionalized, is a suitable scaffold to obtain potential anti-HCV agents. Interestingly, during identification of possible cellular and viral targets, it was discovered that compound 23 exerts inhibitory activity on the HCV NS3 helicase, a very promising target for the development of anti-HCV drugs