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The study of Thermal Protection Systems (TPS) is largely performed in Plasma Wind Tunnel (PWT) facilities where sample wear rate is of main interest and the knowledge of its relation with sample surface temperature desirable. The intrusive and indirect methods employed so far reduce the reliability and the accuracy of these tests. A new joined technique based on both the Surface Layer Implantation of radioactive tracers and on the emissivity-free Dual Color Infra-Red thermography allows the online measure of both the TPS wear rate and the surface temperature without any preparation (i.e. modification) of the sample. Other Ion Beam Analysis techniques like the Rutherford Backscattering Spectrometry (RBS) can be employed off-line to perform integrative, quantitative and still not intrusive analysis of TPS composition and of the structure modifications occurred during the PWT tests. In this work we present the results of a discrete wear rate measurement of an ablative TPS implanted with 7Be ions and the feasibility study of the RBS technique to investigate the oxidation of ceramic TPS.

The highly combustible nature of hydrogen poses a great hazard, creating a number of problems with its safety and handling. As a part of safety studies related to the use of hydrogen in a confined environment, it is extremely important to have a good knowledge of the dispersion mechanism. The present work investigates the concentration field and flammability envelope from a small scale leak. The hydrogen is released into a 0.47 m × 0.33 m x 0.20 m enclosure designed as a 1/15 – scale model of a room in a nuclear facility. The performed tests evaluates the influence of the initial conditions at the leakage source on the dispersion and mixing characteristics in a confined environment. The role of the leak location and the presence of obstacles, are also analyzed. Throughout the test, during the release and the subsequent dispersion phase, temporal profiles of hydrogen concentration are measured using thermal conductivity gauges within the enclosure. In addition, the BOS (Background Oriented Schlieren) technique is used to visualise the cloud evolution inside the enclosure. These instruments allow the observation and quantification of the stratification effects.

The paper deals with the structural behaviour of masonry arches strengthened through fibre reinforced composites with inorganic matrix (Textile Reinforced Mortar, TRM). Two innovative composites are considered: basalt fibre textile coupled with a lime-based matrix and carbon fibre textile associated with a cement-based matrix. Experimental results on bond capacity between composites and bricks and on the structural behaviour of unreinforced and extrados-reinforced, 1:2 scale masonry arches, tested under vertical load are presented. Experimental evidence is compared with outcomes obtained through an analytical model that exploits the stationarity of potential energy of acting forces within the assumption of large displacements. The effect of the reinforcement strip is taken into account retrieving the force-displacement relationship directly from experimental results of bond test. Results show that the analytical model provides a safety estimation of the peak load reached by the arch model during the test. Good agreement is found comparing the load-displacement diagram of the initial phases of the test and the estimations of the numerical model. It is highlighted that the bond force of TRM systems, experimentally determined on a straight substrate, offers capacity levels relevantly under those reached on a convex surface like the extrados of an arch.

The formulas provided by the standards or available in the literature for the calculation of the elastic modulus don’t consider many variables that influence the results of flat jack tests such as, first of all, the influence of the wall thickness. In this paper, flat-jack tests were performed - in the laboratory - on masonry wall specimens having the same geometrical and mechanical properties but different thickness. Then, a numerical assessment by FEM was carried out in order to extend the experimental evidences to the case of masonry walls with large thickness. This study allows to more accurately predict the masonry elastic modulus by double flat-jack test and it provides important data useful for the research activity as well as for the engineering practice.

We have chemically modified the frustules of the marine diatom Coscinodiscus concinnus Wm. Smith to properly bind a highly selective bioprobe such as an antibody. By measuring the changes in the photoluminescence emission of diatoms frustules, we have monitored the molecular recognition event between the antibody and its ligand: the dissociation constant estimated is of the same order of that measured by standard Biacore®. The nanostructured silica frustules, a low-cost and natural available material, have shown high sensitivity, equal to 1.2 ± 0.2 nm μM-1, and a detection limit of 100 nM, and thus are quite ideal candidates for lab-on-particle applications. © 2008 Elsevier B.V. All rights reserved.

Mechanical properties of concrete can consistently affect the seismic performance of RC buildings. A proper determination of the concrete strength is therefore essential for a reliable modeling of the structure. The current European Technical Code, Eurocode 8, provides a criterion for the strength assumption related to the knowledge level of the structure, which does not take into account the variability of the strength. If the concrete strength is affected by a large variability, the conventional strength value suggested by Eurocode 8 can be not conservative, since it does not consider the possible torsional effects due to a not homogeneous strength distribution and the reduced capacity of the weaker members. In this paper the effects of the concrete strength variability on the seismic performance are investigated with a case study, that is a 4-storeys 3D framed building. The seismic response of the case study by assuming different amounts of strength variability has been compared with the Eurocode 8 previsions, both in terms of possible torsional effects and seismic performance.

The aim of this study was to review our 18-year experience in the treatment of viable hydatid liver cysts (HLCs) with double percutaneous aspiration and ethanol injection (D-PAI) and to provide indications for the clinical management of HLCs.From January 1989 to December 2007, 127 patients (100 males; 13-80 years) with 184 viable HLCs (137 univesicular, 47 multivesicular; 2.8-20 cm) underwent D-PAI.Ultrasonography (US) showed complete disappearance of 125/184 (68%) cysts; in the remaining 59 cases, an inactive solid (37 cases, 20%) or liquid pattern (22 cases, 12%) was observed with volume decreases of 50-80%. The final US pattern was unmodified during the follow-up in 96.8%. Local recurrences were observed in 5 patients (3.9%): 4 patients with 8 multivesicular cysts and 1 patient with a bilocular cyst (with a solid pattern on US) that ruptured into the biliary tree 2 years after the procedure and disappeared after endoscopic sphincterectomy. The mortality rate was 0.8%, and the overall morbidity was 8.6%. The mean hospital stay was 2.9 days. The time of healing for smaller cysts (5 cm) was shorter than that of large cysts (≥5 cm) (P 0.001).Our long-term results confirm the high effectiveness of D-PAI in the treatment of HLCs. These results suggest that multilocular cysts require closer follow-up than unilocular cysts.Sommario SCOPO: Scopo di questo studio è stato quello di riportare i risultati a lungo termine del trattamento percutaneo delle cisti idatidee epatiche con doppia puntura – aspirazione – e iniezione di etanolo/(D-PAI). MATERIALI E METODI: Centoventisette pazienti con 184 cisti idatidee epatiche vitali (137 univescicolari, 47 multivescicolari) sono stati sottoposti a D-PAI. RISULTATI: All'esame ecografico si osservava restitutio ad integrum del parenchima epatico in 125 (68%) delle 184 cisti trattate. Per le rimanenti 59, era visibile una riduzione volumetrica del 50–80%. L'aspetto ecografico risultava immodificato per tutta la durata del follow-up nel 96,8% dei pazienti, fatta eccezione per 5 (3,9%) pazienti (4 con cisti multivescicolari, 1 con cisti biloculare) che presentavano recidive locali. CONCLUSIONI: I nostri dati confermano l'elevata efficacia della D-PAI nel trattamento percutaneo delle cisti idatidee epatiche e suggeriscono uno stretto follow-up nei pazienti con cisti multivescicolari.

The seismic response of single storey asymmetric structures modelled as two-degree-of-freedom elastic-perfectly plastic oscillators and designed using the design eccentricity formula of the present Uniform Building Code (UBC) torsional provisions, which first appeared in the 1988 edition, is compared with designs based on the earlier UBC 1979. Changes in the total strength requirement and its distribution among the resisting elements are examined, and the effects of these changes on the ductility demand of three-and five-element systems are evaluated. Jt is shown that for two levels of the strength reduction factor R (= 4;1) the ductility demands predicted for systems designed according to the UBC 79 provisions are in most cases similar to those for UBC 88 systems, with the exception of torsionally flexible systems - mainly mass eccentric and, to a much lesser extent, stiffness eccentric systems. In view of the relative complexity of the UBC 88 provisions, a modification of the simpler UBC 79 ones is proposed which results in the UBC 79 torsionally flexible systems behaving in a similar and often better manner than their UBC 88 counterparts.

In recent years, the moment-rotation response of double angle shear connections has been examined in depth. However, the response of these connections to applied axial force has not been studied so extensively. This paper presents two models of the behavior of double angle shear connections subjected to axial load, which are based on the physical behavior of test specimens that were subjected to axial force until failure. The proposed models, which map design characteristics of double angle connections into actual behavior, yielded good correlation with the experimental results.